Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/21/13
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
945 AM MST THU DEC 19 2013
.SYNOPSIS...
A DEEP LOW PRESSURE SYSTEM WILL APPROACH THE DESERT SOUTHWEST TODAY
LEADING TO LOCALLY BREEZY CONDITIONS AND INCREASING CLOUDS.
PRECIPITATION CHANCES WILL BEGIN LATE THIS AFTERNOON...EXPANDING
THIS EVENING AND OVERNIGHT...THEN TAPERING OFF FROM WEST TO EAST BY
FRIDAY AFTERNOON. A LINGERING CHANCE OF SHOWERS MAY CONTINUE OVER
HIGHER TERRAIN LOCATIONS INTO SATURDAY MORNING. THE SYSTEM WILL ALSO
BRING MUCH COOLER TEMPERATURES...GENERALLY BELOW THE SEASONAL
AVERAGE HEADING INTO THE WEEKEND. EXPECT DRY CONDITIONS WITH A SLOW
WARMING TREND DURING THE FIRST HALF OF NEXT WEEK.
&&
.DISCUSSION...
STILL MOSTLY CLOUD FREE ACROSS THE CWA AS THE POSITIVELY TILTED
UPPER LOW SLIDES SOUTHEASTWARD ALONG THE CALIFORNIA COAST. AT THIS
TIME THE SYSTEM REMAINS FAIRLY MOISTURE STARVED...BUT A PLUME OF
MOISTURE IS BEGINNING TO SHOW UP JUST TO THE SOUTHWEST OF SAN DIEGO
ON WATER VAPOR IMAGERY. AS THE LOW SHIFTS SOUTHWARD THIS
AFTERNOON...MID LEVEL WINDS WILL BACK TO THE SOUTH ACROSS SOUTHERN
ARIZONA ALLOWING FOR MOISTURE ADVECTION INTO THE REGION. LATEST HRRR
MODEL RUN INDICATES SOME SHOWER DEVELOPMENT BY AROUND MID AFTERNOON
ACROSS MARICOPA COUNTY AND OUR FAR WESTERN ZONES. GIVEN THE 20-30
KNOTS LOW LEVEL SOUTHERLY WINDS ALREADY IN PLACE...INCREASING
MOISTURE...AND MODERATE ASCENT SHOWN ON FORECAST ISENTROPIC 300-310K
SURFACES...THE HRRR COULD VERY WELL BE CORRECT IN SHOWING AN EARLIER
SHOWER DEVELOPMENT. SO...HAVE INTRODUCED SOME SLIGHT CHANCE POPS
ACROSS SOUTH-CENTRAL ARIZONA LATE THIS AFTERNOON AND ALSO BUMPED UP
POPS INTO THE LIKELY CATEGORY FOR THIS EVENING. THE STRONGEST
FORCING AND THE BEST UNSTABLE LAPSE RATES WILL OCCUR AS THE LOW
CENTER MOVES ACROSS SOUTHERN ARIZONA APPROXIMATELY BETWEEN 09-18Z
FRIDAY. CONFIDENCE IS GROWING THAT THE MAJORITY OF THE REGION WILL
SEE SOME MEASURABLE RAINFALL FROM THIS EVENT SOMETIME LATE TONIGHT
INTO FRIDAY.
&&
.PREVIOUS DISCUSSION...
EARLY MORNING WV IMAGERY DEPICTS A POTENT UPPER LOW CONTINUING TO
TAKE SHAPE OFF THE NORTHERN CALIFORNIA COAST. QUITE A BIT OF DRYING
IN THE UPPER LEVELS FROM ARIZONA ACROSS THE GULF OF CALIFORNIA AND
WESTWARD OUT INTO THE PACIFIC...BUT THIS SHOULDNT PLAY A
SIGNIFICANT ROLE IN OUR WEATHER ACROSS THE DESERT SOUTHWEST AS THIS
DRYING WILL BE DISPLACED WELL SOUTH OF THE INTERNATIONAL BORDER
LATER THIS AFTERNOON. MEANWHILE...EARLY MORNING TEMPERATURES ARE
GENERALLY IN THE MID 40S AND LOWER 50S AS OF 09Z WITH LIGHT WINDS
AND DECREASING CLOUDS.
IN THE VERY SHORT TERM THROUGH MID MORNING...SURFACE OBS AND GOES
IR/FOG IMAGERY INDICATES SOME AREAS OF FOG AROUND MEXICALI. SURFACE
OBS IN SOUTHEAST CALIFORNIA HAVE NOT REPORTED REDUCED VSBYS BUT
MMML WENT DOWN TO 1/16SM A FEW HOURS AGO AND SATELLITE CLEARLY SHOWS
A FOG BANK HEADING UP TOWARD EL CENTRO. AS THE UPPER LOW CONTINUES
TO GET CLOSER TO THE AREA...WINDS SHOULD PICK UP /ALREADY PICKING UP
AT NJK/ AND THAT MAY BE SUFFICIENT FOR IT TO TRANSITION INTO A
STRATUS DECK. BUT IN THE MEANTIME...I HAVE INTRODUCED PATCHY DENSE
FOG INTO THE GRIDS THROUGH MID MORNING. THE FOG DOES NOT LOOK
WIDESPREAD...NOR DOES IT APPEAR TO BE CAUSING ANY SIGNIFICANT
IMPACTS PER INFO FROM CHP. WILL CONTINUE TO MONITOR OBS AND TRENDS
BUT I DO NOT THINK A DENSE FOG ADVISORY IS NECESSARY AT THIS POINT.
THE BIG STORY OBVIOUSLY IS THE UPPER LOW FORECAST TO DROP THROUGH
SOUTHERN CALIFORNIA AND SOUTHWEST ARIZONA LATER TONIGHT INTO FRIDAY.
FOR THE MOST PART THE FORECAST REMAINS ON TRACK WITH CONDITIONS
GRADUALLY MOISTENING THROUGH THE DAY TODAY...RESULTING IN
INCREASING CLOUDS AND COOLER TEMPERATURES. HOWEVER THERE REMAINS
CONSIDERABLE UNCERTAINTY WHEN THE PRECIP WILL BEGIN ACROSS THE
PHOENIX AREA. GFS/EURO SUGGEST PRECIP DEVELOPING AS EARLY AS
06Z...THE SREF CONTAINS MORE THAN A FEW MEMBERS THAT BRING IN PRECIP
AROUND 21Z THIS AFTERNOON. MEANWHILE THE 00Z AND 06Z NAM SUGGEST
PRECIP WILL REMAIN CONFINED TO WESTERN MARICOPA COUNTY AND POINTS
WEST DUE TO QUITE A BIT OF DRY AIR BEING ENTRAINED INTO THE UPPER
LOW FROM THE EAST. NOT GOING TO GO AS AGGRESSIVE AS THE GFS/EURO
BRINGING IN 70-80 POPS THIS EVENING...BUT I FULLY EXPECT SHOWERS TO
DEVELOP OVERHEAD AFTER MIDNIGHT AND I INCREASED POPS QUITE A BIT
AFTER 06Z. WHILE I DO THINK THERE WILL BE A SHARP EDGE TO THE PRECIP
TONIGHT...I THINK THE PHOENIX METRO SEES A DECENT SHOT OF PRECIP
OVERNIGHT INTO FRIDAY MORNING AS THE LOW ARRIVES AND STRONG
SOUTHERLY 850MB WINDS ALIGN WITH THE AXIS OF 0.6-0.8 INCH PWATS.
MEANWHILE...ALL MODELS HAVE COME IN A BIT WETTER ACROSS SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA. POPS WERE BUMPED UP QUITE A BIT
AROUND YUMA/EL CENTRO/BLYTHE ACCORDINGLY.
PRECIP WILL CONTINUE THROUGH THE MORNING HOURS ON FRIDAY AS THE
UPPER LOW DIVES SOUTHWARD THROUGH ARIZONA INTO MEXICO FRIDAY
AFTERNOON. WHILE IM NOT ENTIRELY CONVINCED THERE WILL BE
THUNDER...THERE ARE A FEW HUNDRED J/KG OF MLCAPE TO WORK WITH UNDER
THE CORE OF THE UPPER LOW AND I HELD ONTO THE SLIGHT MENTION OF
THUNDER EARLY FRIDAY MORNING. AT SOME POINT DURING THE AFTERNOON THE
PRECIP SHOULD BEGIN TO TAPER OFF AS THE BEST MOISTURE CONVERGENCE
AND ISENTROPIC ASCENT WILL BE DISPLACED AWAY FROM THE FORECAST
AREA...BUT STRONGLY BACKED WINDS FROM 925-850MB COULD RESULT IN A
QUASI-STATIONARY BAND OF PRECIP SOMEWHERE IN/AROUND/TO THE NORTH OF
THE PHOENIX AREA. QPF FROM THE NAM/GFS/EURO SUGGEST A BAND OF PRECIP
FROM GLOBE TO PHOENIX TO WICKENBURG DURING THE AFTERNOON I HELD ONTO
SOME ELEVATED POPS THROUGH 00Z. CONFIDENCE IN EXACTLY HOW THE AREAL
COVERAGE WILL TURN OUT IS LOW...THUS POPS ARE SOMEWHAT BROAD-BRUSHED
THROUGH THE ENTIRE EVENT. HOWEVER...IT STILL LOOKS LIKE QPF WILL BE
IN THE 0.10-0.30 REALM FOR MOST LOCATIONS...WITH LOCALLY HIGHER
AMOUNTS AS USUAL.
THE LOW WILL SLOWLY DEPART FRIDAY NIGHT INTO SATURDAY BUT MOIST
NORTHWESTERLY FLOW WILL CONTINUE INTO THE DAY ON SATURDAY. LOOKS
LIKE A CONTINUED CHANCE OF SHOWERS AND/OR SNOW IN THE MOUNTAINS EAST
OF PHOENIX THROUGH AT LEAST 18Z SATURDAY...BUT THE DESERTS SHOULD
REMAIN DRY. WITH SNOW LEVELS ONLY EXPECTED TO FALL TO AROUND
5000-5500 FT...NEARLY ALL OF THE HIGH IMPACT HIGHER ELEVATIONS WILL
SEE PRECIP REMAIN AS RAIN AS OPPOSED TO SNOW...BUT THE HIGHEST SPOTS
COULD SEE A QUICK INCH OR TWO OF SNOW BY THE TIME THINGS DRY OUT
ENTIRELY ON SUNDAY.
THE FORECAST FOR MONDAY THROUGH MID WEEK LOOKS DRY AS THE NORTHWEST
FLOW GRADUALLY FLATTENS OUT BY TUESDAY. THERE REMAINS A VARIETY OF
SOLUTIONS SURROUNDING A LOW MOVING SOUTHWARD THROUGH THE FOUR
CORNERS WEDNESDAY AFTERNOON INTO THURSDAY. TODAYS 00Z RUNS OF THE
EURO/GFS KEEP THIS LOW DISPLACED WELL NORTH AND EAST OF THE FORECAST
AREA. THIS IDEA SEEMS TO HAVE THE SUPPORT OF THEIR RESPECTIVE
ENSEMBLES AS WELL. KEPT A DRY FORECAST IN PLACE FOR CHRISTMAS DAY
BUT WILL NEED TO MONITOR TRENDS IN THE EVENT THE MODELS RETURN TO A
DEEPER AND MORE SIGNIFICANT SYSTEM NEXT WEDNESDAY/THURSDAY.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
EASTERLY WINDS TO PERSIST THROUGH THE MORNING HOURS...WITH THICK
CIRRUS COVER GENERALLY THINNING. SURFACE WINDS INCREASE AFTER 17Z
WITH A SOUTHERLY CROSS COMPONENT AOA 10KT AND HIGHER GUSTS UP TO
20KT POSSIBLE THIS AFTERNOON. INCREASING CIGS BELOW 6KFT LIKELY
THURSDAY EVENING...WITH SHOWERS AND ISOLATED THUNDERSTORMS
DEVELOPING OVERNIGHT INTO FRIDAY MORNING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH...
EXPECT INCREASED SOUTHWEST TO WEST WINDS...WITH GUSTS OF 25-30KT
COMMON THROUGH THE DAY. INCREASING/LOWERING CLOUD DECKS ALSO
EXPECTED BY THE LATE AFTERNOON WITH LOWER CIGS AROUND 6KFT AND
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE THIS
EVENING...CONTINUING INTO FRIDAY MORNING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
MOSTLY SUNNY SKIES WILL PREVAIL...AND A GRADUAL WARMING TREND WILL
TAKE PLACE THROUGH THE WEEKEND. HIGH TEMPERATURES WILL STAY BELOW
SEASONAL NORMALS...ESPECIALLY OVER SOUTH CENTRAL ARIZONA WHERE MAX
READINGS ARE EXPECTED TO BE THE UPPER 50S TO AROUND 60 DEGREES.
NORTHWEST WINDS WILL REMAIN BREEZY ACROSS SOUTHWEST ARIZONA AND
SOUTHEAST CALIFORNIA SATURDAY...WITH A LIGHTER WIND REGIME EXPECTED
AREA-WIDE SUNDAY THROUGH TUESDAY. MINIMUM HUMIDITIES WILL REMAIN
ELEVATED AND MOSTLY GREATER THAN 20 PERCENT THROUGH THE PERIOD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...KUHLMAN
PREVIOUS DISCUSSION...LEINS
AVIATION...MEYERS
FIRE WEATHER...MEYERS
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
352 PM MST THU DEC 19 2013
.SHORT TERM...SOUTHWEST FLOW ALOFT CURRENTLY ACROSS COLORADO. MID
LEVEL MOISTURE SPREADING BACK INTO THE MOUNTAINS AND FROM WEB CAMS
IT APPEARS THERE IS SOME LIGHT SNOW OVER THE HIGHER MOUNTAINS.
SNOW COVERAGE WILL GRADUALLY INCREASE THIS EVENING AS MOISTURE AND
OROGRAPHICS INCREASE...WITH THE FLOW FAVORING THE NORTHERN
MOUNTAINS. BUT THE SNOW WILL BE LIGHT DUE TO LACK OF ANY MID LEVEL
ASCENT... WITH ACCUMULATIONS LESS THAN 3 INCHES. AFTER
MIDNIGHT...THE SNOW WILL DECREASE AGAIN AS THE FLOW ALOFT WEAKENS
ALONG WITH WEAKENING OROGRAPHICS. ALONG FOOTHILLS AND ACROSS
PLAINS...COLD FRONT CURRENTLY PUSHING INTO NORTHERN COLORADO WITH
SOME GUSTS TO AROUND 25 KTS. FRONT WILL CONTINUE TO MOVE SOUTH
THROUGH THE EVENING WITH UPSLOPE DEVELOPING AND LOW LEVEL MOISTURE
INCREASING. CROSS SECTIONS SHOW UPSLOPE TO BE AROUND 700 MB NEAR
THE FOOTHILLS. THERE STILL LOOKS TO BE WINDOW BETWEEN 02Z AND 07Z
FOR SOME LIGHT SNOW TO DEVELOP...MAINLY IN AND NEAR THE FOOTHILLS.
LATEST RAP ALSO SHOWS SOME CHANCE ALONG THE PALMER. STILL THE BEST
CHANCE FOR SNOW WILL BE ACROSS ZONE 35 WHERE LOW LEVEL UPSLOPE
WILL BE AIDED WITH THE SOUTHWEST FLOW ALOFT AND WILL CONTINUE
LIKELY POPS THERE WITH SNOW AMOUNTS AROUND AN INCH. WILL KEEP A
CHANCE OF LIGHT SNOW ALONG THE URBAN CORRIDOR AND SOUTHERN
FOOTHILLS WITH LOWER POPS FURTHER EAST. AFTER 07Z THE UPSLOPE
WEAKENS AND THE AIRMASS BEGINS TO DRY OUT...LOWER POPS STILL LOOK
REASONABLE. AIRMASS FAIRLY COLD OVER WYOMING AND NEBRASKA...AND
THIS AIR SHOULD STAY TO THE NORTH AND EAST OF COLORADO.
STILL...OVERNIGHT TEMPERATURES TO DROP INTO THE TEENS ACROSS THE
PLAINS...WITH SINGLE DIGIT READINGS NEAR THE WYOMING AND NEBRASKA
PANHANDLE. ON FRIDAY...FLOW ALOFT BECOMES WESTERLY...A BIT
NORTHWEST AT MOUNTAIN TOP DURING THE AFTERNOON. THERE IS ALSO SOME
INCREASE IN MID LEVEL ASCENT. THIS WILL RESULT IN SOME INCREASE IN
LIGHT SNOW BY THE AFTERNOON. STILL ACCUMULATIONS WILL REMAIN
LIGHT. ACROSS PLAINS...A DRIER BUT COLD AIRMASS WILL BE OVER THE
AREA. THERE MAY BE SOME LINGERING FLURRIES DURING THE
MORNING...OTHERWISE NO SNOW IS EXPECTED. TEMPERATURES WILL SLOWLY
WARM INTO THE 30S ACROSS THE PLAINS...EXCEPT UPPER 20S FAR
NORTHEAST CORNER.
.LONG TERM...DRYING AND SUBSIDENCE THROUGH TOMORROW EVENING SHOULD
BRING A DECREASE OF SNOW SHOWERS IN THE MOUNTAINS. HOWEVER...THE
NEXT SHORT WAVE IS QUICK ON ITS HEELS WHICH WILL BRING A RETURN OF
HIGH COUNTRY SNOWFALL BY EARLY SATURDAY MORNING. MOISTURE IS
DEEPER BUT STABILITY PROFILE IS ONLY MARGINAL WITH A STABLE LAYER
NEAR MOUNTAIN TOP BUT OK 5-6C/KM LAPS RATES FARTHER UP. THE END
RESULT SHOULD BE A LIGHT SNOW EVENT FOR MOUNTAINS STANDARDS WITH
ANOTHER 1-4 INCHES SATURDAY.
BY LATE SATURDAY AFTERNOON AND EVENING...THERE IS SOME LOW LEVEL
ANTICYCLONIC TURNING WHICH COULD ALLOW A LITTLE SNOW TO SPILL OUT
ONTO THE PLAINS IN SHALLOW UPSLOPE. AT THIS TIME...THIS ONLY
LOOKS LIKE A LIGHT DUSTING IF ANYTHING SO WILL CONTINUE THE LOW
POPS FOR SATURDAY EVENING.
BY LATE SUNDAY...ANOTHER FAST MOVING SHORT WAVE MAY APPROACH FROM
THE NORTHWEST BRINGING MORE MOUNTAIN SNOW SHOWERS. AGAIN..THERE
MAY BE A LOW CHANCE ON THE PLAINS WITH A WEAK FRONTAL SURGE AND
LIFT ASSOCIATED WITH LEFT EXIT REGION OF UPPER JET. HAVE THROWN IN
SOME POPS FOR THE NORTHEAST CORNER OF THE STATE...BUT EVENTUALLY MAY
HAVE TO INCLUDE THE FRONT RANGE URBAN CORRIDOR CONSIDERING THIS IS
A NORTHWEST FLOW EVENT WITH A STRONG UPPER JET. TEMPERATURES WILL
AVERAGE A FEW DEGREES BELOW NORMAL FOR THE SATURDAY-SUNDAY PERIOD.
MAINLY DRY AND WARMER WEATHER IS EXPECTED MONDAY INTO TUESDAY.
THEN...ANOTHER SHORT WAVE IS ADVERTISED BY MOST MEDIUM RANGE
MODELS TO DROP ACROSS THE STATE CHRISTMAS EVE INTO CHRISTMAS
MORNING. TIMING IS BECOMING INCREASINGLY DIFFICULT IN THIS FAST
NORTHWEST FLOW PATTERN...SO EXTENDED PERIODS OF LOW POPS IS
WARRANTED FOR NOW. THAT PARTICULAR WAVE WILL BE THE PLAINS BEST
CHANCE OF A WHITE CHRISTMAS.
&&
.AVIATION...FRONT MOVING INTO NORTHERN WELD COUNTY...SHOULD REACH
THE AREA AIRPORTS BY 00Z. NORTHERLY WINDS WILL GUST TO AROUND 25
KTS WITH THE FRONT PASSAGE. CLOUDS WILL CONTINUE TO INCREASE WITH
CEILINGS LOWERING TO IFR BY 01Z WITH DECREASING WINDS. THERE IS
STILL A CHANCE FOR LIGHT SNOW BETWEEN 02Z AND 08Z...THOUGH THIS
CHANCE IS DECREASING AS THE MOISTURE IS BECOMING MORE SHALLOW.
WILL CONTINUE THE VCSH FOR NOW. CONDITIONS TO IMPROVE AFTER 08Z
WITH WINDS SHIFTING TO THE SOUTHEAST. AFTER 13Z SHOULD SEE
CEILINGS IMPROVE TO VFR.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1019 PM EST FRI DEC 20 2013
.SYNOPSIS...
ANOTHER ROUND OF SCATTERED SHOWERS IS EXPECTED OVERNIGHT...MAINLY
ALONG AND NORTH OF THE MA TURNPIKE. A FRONTAL BOUNDARY WILL
GENERALLY BE TO THE NORTH OF THE REGION THROUGH MONDAY. PERIODS OF
RAIN SHOWERS AND UNSEASONABLY MILD TEMPS ARE EXPECTED...ESPECIALLY LATE
SAT NIGHT INTO MON. MAINLY DRY AND MUCH COLDER WEATHER ARRIVES TUE
AND WED.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
1015 PM UPDATE...
LATEST RADAR IMAGERY SHOWED A BLOSSOMING AREA OF RAIN SHOWERS
ACROSS UPSTATE NEW YORK AND NORTHEAST PENNSYLVANIA. THIS A RESULT
OF CONTINUED WARM ADVECTION ALOFT. THE HRRR MODEL SEEMS TO HAVE A
PRETTY GOOD HANDLE ON THIS SITUATION AND EXPECT A ROUND OF
SCATTERED RAIN SHOWERS...MAINLY ALONG AND NORTH OF THE MA TURNPIKE
LATER TONIGHT. CERTAINLY NOT EXPECTING A WASHOUT IN THIS REGION...
JUST A PERIOD OF SOME SCATTERED RAIN SHOWERS. ADJUSTED TIMING
SLIGHTLY TO REFLECT THE LATEST OBSERVED TRENDS.
LOW TEMPERATURES WILL REMAIN AT OR ABOVE FREEZING TONIGHT WITH
SOUTHWEST WINDS AND A FAIR AMOUNT OF MID LEVEL CLOUDINESS. THERE
IS A LOW PROBABILITY THAT TEMPERATURES COULD TOUCH FREEZING
ACROSS PORTIONS OF NORTHWEST MA/SOUTHWEST NH. IF THIS OCCURS...IT
MAY RESULT IN A FEW PATCHES OF BLACK ICE OR FREEZING RAIN.
AGAIN...ODDS FAVOR IT REMAINING ABOVE FREEZING WITH ONLY RAIN
FALLING. GIVEN THE LIMITED POTENTIAL FOR ICING...NO PLANS TO ISSUE
EITHER A FREEZING RAIN ADVISORY OR STATEMENT AT THIS TIME.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
SATURDAY INTO SATURDAY NIGHT...ELONGATED BOUNDARY REMAINS OVER
NORTHERN NEW ENGLAND TOMORROW AND INTO TOMORROW NIGHT KEEPING MUCH
OF THE REGION IN THE WARM SECTOR. THIS COULD ALLOW FOR THE LOW
CLOUDS TO REMAIN ACROSS THE REGION TAMPERING WITH THE POTENTIAL
WARM UP EXPECTED FOR TOMORROW. ALTHOUGH LOW TO MID 50S IS NOT OUT
OF THE QUESTION...IT IS POSSIBLE THAT THIS COULD BE TO WARM IF THE
LOW CLOUDS STAY PUT. THE NEXT FORECASTER WILL NEED TO MONITOR THIS
POTENTIAL.
ANOTHER WAVE OF LOW PRESSURE WILL MOVE ALONG THIS BOUNDARY SAT
AFTERNOON AND INTO THE OVERNIGHT HOURS. THIS WAVE WILL BE THE BEST
CHANCE FOR SOME ACCUMULATING PRECIP. TEMPS WILL REMAIN ABOVE
FREEZING OVERNIGHT AND WITH INCREASING DEWPOINTS EXPECT AREAS TO
WIDESPREAD FOG TO DEVELOP...WHICH COULD BE DENSE. MODELS ARE
INDICATING A COLD AIR DAMMING SIGNATURE ACROSS ME AND EASTERN
NH...WHICH COULD COULD DROP INTO SOUTHERN NEW HAMPSHIRE BY 12Z
SUNDAY. IF TEMPS DO DROP BELOW 32F THEN THERE IS THE POTENTIAL FOR
FREEZING RAIN ACROSS IMMEDIATE NORTHERN CHESHIRE AND HILLSBOROUGH
COUNTIES IN NH. THERE IS STILL A LOW CONFIDENCE FORECAST AND IT IS
ALL DEPENDS ON HOW FAR SOUTH THAT COLD AIR MOVES. WE WILL CONTINUE
TO WATCH THIS SIGNATURE AND THE THREATS THAT MAY PERTAIN TO IT.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
HIGHLIGHTS...
* LOW PROBABILITY FOR A PERIOD OF FREEZING RAIN IN SOUTHERN NH SUNDAY
* DENSE FOG A CONCERN ACROSS THE INTERIOR ON SUNDAY
* PERIODS OF RAIN SHOWERS SUN/MON WITH WELL ABOVE NORMAL TEMPS
* MUCH COLDER AND MAINLY DRY WEATHER TUE/WED
DETAILS...
SUNDAY...
LOW CONFIDENCE FORECAST CONTINUES IN REGARDS TO TEMPERATURES. LOW
PRESSURE WILL BE PASSING TO THE WEST OF OUR REGION...BRINGING VERY
WARM MID LEVEL AIR INTO NEW ENGLAND. HOWEVER...A LARGE SURFACE HIGH
STRETCHING ACROSS CENTRAL/EASTERN CANADA WILL SEND A SURGE OF
SHALLOW COLD AIR SOUTHWARD. THE MAIN CONCERN WILL BE IF TEMPS CAN
FALL TO OR JUST BELOW 32 DEGREES FOR A TIME ACROSS PORTIONS OF
SOUTHERN NH. MOST MODELS KEEP THAT JUST TO OUR NORTH...BUT GIVEN THE
STRENGTH OF THE HIGH AND SHALLOW COLD AIR...WOULD NOT BE IMPOSSIBLE
FOR THAT TO OCCUR FOR AT LEAST A TIME ACROSS SOUTHERN NH.
THEREFORE...THINK THERE REMAINS A LOW PROBABILITY FOR A PERIOD OF
FREEZING RAIN ACROSS PORTIONS OF SOUTHERN NH. THE SIGNIFICANT ICING
POTENTIAL LOOKS TO REMAIN TO OUR NORTH.
AS FOR PRECIP CHANCES...A STRONG LOW LEVEL JET IMPINGING ON THE
BOUNDARY WILL RESULT IN RAIN SHOWERS...WITH THE ACTIVITY BEING MOST
NUMEROUS TO THE NORTH OF ROUTE 2 IN THE VICINITY OF THE BOUNDARY. A
PERIOD OF HEAVY RAIN IS EVEN POSSIBLE ACROSS OUR FAR NORTHERN ZONES
BUT SOUTH OF THE MA TURNPIKE JUST A FEW SHOWERS ARE EXPECTED
AND A FAIR AMOUNT OF THE DAY MAY END UP DRY.
THERE ALSO WILL BE A GOOD CHANCE FOR AREAS OF DENSE FOG ACROSS
INTERIOR SOUTHERN NEW ENGLAND. THIS A RESULT OF HIGH DEWPOINT AIR
OVER RUNNING THE DEEP SNOW PACK...SO A DENSE FOG ADVISORY MAY BE
NEEDED.
LASTLY...HIGH TEMP FORECASTS ON SUNDAY ARE OF VERY LOW CONFIDENCE.
AREAS SOUTH OF THE MA TURNPIKE SHOULD WARM SECTOR AND HIGHS WILL
PROBABLY EXCEED 60 DEGREES! IT MAY BE MUCH COOLER NORTH OF MA
TURNPIKE...ESPECIALLY IN FAR NORTHEAST MA/SOUTHEAST NH WHERE
BOUNDARY MAY NOT MIX OUT. WILL SHOW A LARGE GRADIENT IN EXPECTED
HIGH TEMPS ON SUNDAY...BUT LATER SHIFTS MAY CERTAINLY HAVE TO
REFINE.
SUNDAY NIGHT...
AN UNSEASONABLY MILD NIGHT IS ON TAP ACROSS SOUTHERN NEW ENGLAND
WITH SOUTHWEST FLOW OF VERY MILD AIR. PORTIONS OF THE REGION SOUTH
OF THE MA TURNPIKE PROBABLY WILL NOT DROP BELOW 50 DEGREES! A FEW
LEFT OVER SHOWERS ARE POSSIBLE...BUT MUCH OF THE NIGHT WILL PROBABLY
END UP DRY.
MONDAY AND MONDAY NIGHT...
A SECONDARY WAVE LOOKS TO MOVE UP THE COAST ON MON/MON NIGHT. A
PERIOD OF RAIN SHOWERS WILL BE POSSIBLE ACROSS THE ENTIRE
REGION...BUT HIGHEST PROBABILITIES WILL BE ACROSS EASTERN AND
SOUTHERN SECTIONS. TEMPS WILL STILL BE QUITE MILD ON
MONDAY...ESPECIALLY ACROSS SOUTHEAST NEW ENGLAND WHERE IT SHOULD
AGAIN REACH WELL INTO THE 50S. COLDER AIR WILL WORK IN BEHIND A
COLD FRONT LATE MON AND MON NIGHT. LOW PROBABILITY THAT RAIN COULD
END AS A VERY BRIEF PERIOD OF LIGHT SNOW OR FLURRIES.
TUESDAY AND WEDNESDAY...
MAINLY DRY AND VERY COLD WEATHER TUE/WED WITH BELOW NORMAL TEMPS.
LOW PROBABILITY OF SOME OCEAN EFFECT VERY LIGHT SNOW
SHOWERS/FLURRIES ACROSS PORTIONS OF THE CAPE/NANTUCKET TUE NIGHT/WED
AM WITH NNW WINDS...BUT NOTHING SIGNIFICANT EXPECTED.
THURSDAY AND FRIDAY...
LOW CONFIDENCE FORECAST OVER THIS TIME. TEMPERATURES SHOULD
MODERATE TO SOME DEGREE THU INTO EARLY FRI...BUT ANOTHER SHOT OF
COLDER AIR MAY FOLLOW LATE FRI. JUST INCLUDED A SLIGHT CHANCE POPS
THU NIGHT INTO FRI...GIVEN CONSIDERABLE MODEL DISAGREEMENT.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH SATURDAY NIGHT/...
TONIGHT...LOW CONFIDENCE. GUIDANCE SUGGESTS IFR TO LIFR
DEVELOPING ACROSS THE REGION IN LOW CLOUDS/FOG. GIVEN THAT THERE
ARE NOT ANY LOW CLOUDS OR FOG TO THE SOUTH OF OUR REGION...PLAYED
IT MORE OPTIMISTIC JUST TAKING THINGS DOWN TO MVFR FOR NOW.
CONFIDENCE IS LOW...SO LATER SHIFTS MAY HAVE TO MAKE CHANGES.
SATURDAY AND SATURDAY NIGHT...MODERATE CONFIDENCE.
MVFR CONDITIONS ON SATURDAY WILL DETERIORATE TO IFR AND LIFR
CONDITIONS SATURDAY NIGHT IN LOW CLOUDS/FOG. EXPECT SCT SHOWERS
CHANCE TO INCREASE NORTH OF THE MASS PIKE BY SAT NIGHT AND INTO
EARLY SUN MORNING. LOW PROBABILITY OF LIGHT FREEZING RAIN ACROSS
SOUTHERN NEW HAMPSHIRE OVERNIGHT SATURDAY INTO SUNDAY. O DENSE
FOG DEVELOPMENT IS LIKELY TO DEVELOP SAT NIGHT INTO SUNDAY.
KBOS TAF...LOW TO MODERATE CONFIDENCE IN TAF.
KBDL TAF...LOW TO MODERATE CONFIDENCE IN TAF.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
SUNDAY AND MONDAY...MODERATE CONFIDENCE. PERIODS OF MVFR-IFR
CONDITIONS IN MAINLY RAIN SHOWERS/LOW CLOUDS AND AREAS OF FOG. FOG
COULD BE DENSE AT TIMES ESPECIALLY ON SUNDAY...RESULTING IN EVEN
LIFR CONDITIONS.
TUESDAY AND WEDNESDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR
CONDITIONS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH SATURDAY NIGHT/...HIGH CONFIDENCE
SW FLOW WILL CONTINUE OVER THE WATERS THROUGH THE PERIOD. EXPECT
OCCASIONAL GUSTS ABOVE 25 KT...ESPECIALLY ACROSS THE OUTER WATERS
THROUGH THIS WEEKEND. OTHERWISE SEAS WILL BE INCREASING FROM THE
SW FETCH THAT IS DEVELOPING. EXPECT 5 FT ON THE NORTHEASTERN
OUTER WATERS...BUT THE SOUTHERN WATERS WILL INCREASE TO AT LEAST
8FT. SCA HAS BEEN EXTENDED ACCORDINGLY. HAVE A LOW CONFIDENCE ON
WINDS ACROSS THE BAYS SO HAVE HELD OFF ISSUANCE FOR NOW.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
SUNDAY AND SUNDAY NIGHT...MODERATE CONFIDENCE. SOUTHWEST FLOW WILL
RESULT IN STRONG SCA WIND GUSTS AND HIGH SEAS ACROSS OUR SOUTHERN
WATERS. LOW PROBABILITY FOR A PERIOD OF GALES...BUT KEPT THINGS
BELOW FOR NOW WITH THE INVERSION OVER THE WATERS. ACROSS OUR NORTHERN
WATERS...LOW CONFIDENCE AS FRONT FROM THE NORTH MAY SWITCH WINDS TO
THE NORTH FOR A PERIOD OF TIME. UNCERTAIN HOW FAR SOUTH THIS FRONT
WILL GET.
MONDAY...MODERATE CONFIDENCE. WINDS DIMINISH BELOW SCA THRESHOLDS
AS PRESSURE GRADIENT WEAKENS. SEAS WILL DIMINISH BUT REMAIN ABOVE
SCA THRESHOLDS ACROSS THE OUTER ATLANTIC WATERS.
MONDAY NIGHT THROUGH TUESDAY NIGHT...MODERATE CONFIDENCE. COLD
FRONT CROSS THE REGION MON NIGHT SHIFTING THE WINDS TO NORTHWEST.
STRONG COLD ADVECTION SHOULD YIELD NORTHWEST SCA WIND GUSTS OF 25 TO
30 KNOTS OVER THE OPEN WATERS MOST OF THE TIME.
WEDNESDAY...MODERATE CONFIDENCE. WINDS AND SEAS SHOULD DROP BELOW
SCA THRESHOLDS DURING THE DAY AS STRONG HIGH PRESSURE BUILDS OVER
THE WATERS.
&&
.CLIMATE...
RECORD HIGHS FOR DECEMBER 22ND...
HARTFORD /BDL/ 59 DEGREES...1990
WORCESTER /ORH/ 63 DEGREES...1923
BOSTON /BOS/ 62 DEGREES...1990
PROVIDENCE /PVD/ 61 DEGREES...1990
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...AIR QUALITY ALERT UNTIL 11 PM EST SATURDAY FOR NHZ011.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR ANZ235-237-250-
254>256.
&&
$$
SYNOPSIS...FRANK/DUNTEN
NEAR TERM...BELK/FRANK
SHORT TERM...DUNTEN
LONG TERM...FRANK
AVIATION...FRANK/DUNTEN
MARINE...FRANK/DUNTEN
CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS ALBANY NY
959 PM EST FRI DEC 20 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM THE GREAT LAKES THROUGH NORTHERN
NEW YORK AND NORTHERN NEW ENGLAND WILL PRODUCE SCATTERED LIGHT
PRECIPITATION TONIGHT. THE FRONT WILL SINK SOUTH AS A COLD FRONT
INTO PARTS OF CENTRAL NEW YORK AND SOUTHERN VERMONT BY SATURDAY
NIGHT...SUPPORTING CHANCES FOR FREEZING RAIN IN THE NORTH COUNTRY.
STRONG LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE TENNESSEE AND
OHIO VALLEY SUNDAY AS THE FRONT SURGES NORTH INTO CANADA.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 959 PM EST...BATCHES OF MAINLY LIGHT RAIN CONTINUE TO MOVE
ACROSS THE NORTHERN HALF OF THE AREA LATE THIS EVENING. MADE SOME
MINOR ADJUSTMENTS TO POPS BASED ON LATEST OBS/TRENDS. WILL MENTION
LIKELY OR HIGHER POPS FROM THE CAPITAL REGION NORTHWARD THROUGH
MUCH OF THE NIGHT. THERE MAY BE A BRIEF BREAK LATER TONIGHT AS
DEPICTED BY THE HRRR AND LOCAL HIRES WRF. TEMPERATURES ARE STILL
ABOVE FREEZING ACROSS MUCH OF THE AREA EXCEPT FOR A LIMITED AREA
OF FAR NORTHERN WARREN AND WASHINGTON COUNTIES WHERE NORTHERLY
WINDS HAVE ALLOWED COLD AIR TO DRAIN SOUTHWARD THROUGH THE
CHAMPLAIN VALLEY TO THE LAKE GEORGE REGION. A FREEZING RAIN
ADVISORY REMAINS IN EFFECT THERE THROUGH 6 AM. WILL CONTINUE TO
MENTION UP TO ONE TENTH OF AN INCH OF ICE IN THIS SMALL AREA. FOR
SOME AREAS WHERE MIXING HAS BEEN ABLE TO OCCUR...TEMPS HAVE RISEN
INTO THE LOWER TO MID 40S. TEMPERATURES ARE GENERALLY EXPECTED TO
REMAIN STEADY THROUGH THE NIGHT.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
STRONGER UPPER LEVEL ENERGY...FORCING AND MOISTURE ADVECTION
APPROACHES SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. HEAVIER
RAINFALL SHOULD SPREAD ACROSS THE REGION SATURDAY AFTERNOON AND
NIGHT...WITH THE HEAVIEST RAIN OCCURRING SATURDAY NIGHT INTO EARLY
SUNDAY. THERE ARE CONSIDERABLE DISAGREEMENTS IN SOURCES OF GUIDANCE
AND ENSEMBLES AS TO HOW MUCH COLDER AIR SINKS SOUTH SATURDAY NIGHT
IN RESPONSE TO ENHANCED UPPER CONFLUENCE IN CANADA AS UPPER ENERGY
TRACKS WELL NORTH OF THE U.S. CANADIAN BORDER. ENOUGH COLD AIR COULD
SINK SOUTHWARD AGAIN SATURDAY NIGHT TO PRODUCE SOME FREEZING RAIN.
MODELS INDICATE THAT ANY PERIOD OF NEAR OR BELOW FREEZING TEMPS
ALONG THE NORTHERN BORDER OF THE FORECAST AREA WOULD BE BRIEF AND
ONLY PRODUCE LIGHT ICING AMOUNTS (UNDER A QUARTER OF AN INCH). NO
WINTER STORM WATCH WILL BE ISSUED AND IF APPEARS MORE CERTAIN THAT
SOME FREEZING RAIN WILL FALL LATE SATURDAY NIGHT...THEN ADVISORIES
CAN BE ISSUED ON SATURDAY.
A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...ALONG
WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY RAIN EVENT...AND
COMBINED WITH SNOW MELT...COULD RESULT IN SOME FLOODING POTENTIAL.
THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL FORECASTS FROM SOURCES
OF GUIDANCE AND ENSEMBLES STILL INDICATE THAT A BROAD RANGE AND AXIS
OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM SNOW MELT OCCURS.
A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY RESULTS IN THE
HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH AGAIN MAY SEE THE
LEAST WARM TEMPERATURES AND LEAST SNOW MELT. SO...STILL HOLDING OFF
ON ANY FLOOD WATCHES.
HIGHS SATURDAY IN THE 40S TO LOWER 50S...LOWS SATURDAY IN THE 40S
OVER THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA...AND 30S NORTH.
HIGHS SUNDAY 45 TO 55 NORTH...AND 55 TO 65 SOUTH. LOWS SUNDAY NIGHT
IN THE 40S SOUTH...30S NORTH.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE PERIOD STARTS OUT ON MONDAY WITH COLDER AIR GRADUALLY FILTERING
INTO THE REGION WITH A WSW FLOW BECOMING WNW. A FRONTAL BOUNDARY TO
OUR SOUTH OVER THE MID ATLANTIC REGION IS FORECAST TO STALL...WITH A
WAVE OF LOW PRESSURE MOVING NORTHEASTWARD ALONG THE FRONT. SOME
LIGHT RAIN ASSOCIATED WITH THIS WAVE COULD AFFECT AREAS MAINLY SOUTH
AND EAST OF ALBANY. THE GFS/ECMWF HAS SOME LIGHT QPF JUST SCRAPING
OUR SOUTHEAST ZONES...WHILE THE NAM IS MOST AGGRESSIVE WITH BRINGING
THE WAVE AND ASSOCIATED QPF NORTHWARD. WILL MENTION CHANCE POPS FOR
NOW...WITH ANOTHER AREA OF CHANCE POPS ACROSS NORTHWEST AREAS DUE TO
SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS DEVELOPING.
TEMPERATURES SHOULD DROP SIGNIFICANTLY MONDAY NIGHT INTO CHRISTMAS
EVE MORNING...AS STRONG COLD ADVECTION COMMENCES. THE FLOW
TRAJECTORY IS FORECAST TO SHIFT TO THE NORTHWEST...SO SOME
MULTI-BAND LAKE EFFECT SNOW SHOWERS COULD IMPACT THE MOHAWK AND
SCHOHARIE VALLEY...AS WELL AS THE NORTHERN CATSKILLS CHRISTMAS EVE
DAY. CHRISTMAS EVE NIGHT THROUGH CHRISTMAS DAY LOOKS TO BE DRY BUT
COLD REGION-WIDE...AS HIGH PRESSURE BUILDS IN THEN SHIFTS EASTWARD
INTO NEW ENGLAND BY LATE CHRISTMAS DAY. DRY CONDITIONS SHOULD
PERSIST WEDNESDAY NIGHT...ALTHOUGH A BIT OF A SOUTHERLY GRADIENT
DEVELOPS AROUND THE DEPARTING HIGH WHICH COULD ALLOW FOR MILDER
TEMPERATURES DEPENDING ON THE AMOUNT OF MIXING AT NIGHT.
THE FORECAST BECOMES A BIT MORE MURKY FROM THURSDAY INTO FRIDAY...AS
ENERGY ASSOCIATED WITH AN UPPER LEVEL TROUGH MOVES EASTWARD ACROSS
THE GREAT LAKES...WHILE THERE IS THE POTENTIAL FOR A SOUTHERN STREAM
DISTURBANCE TO PHASE WITH THE PRIMARY TROUGH. THE ECMWF IS MOST
AGGRESSIVE WITH THIS SCENARIO...WHICH COULD LEAD TO A MORE
WIDESPREAD MODERATE PRECIP EVENT. THE GFS IS MUCH MORE PROGRESSIVE
THOUGH...SO WILL CONSERVATIVELY MENTION LOW CHANCE POPS AT THIS TIME.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
LIGHT RAIN TO IMPACT MAINLY THE NORTHERN TAFS THIS AFTERNOON
ALTHOUGH FOR THE MOST PART THE IMPACT SHOULD BE MARGINAL. WE DID
INCLUDE A 3-HR TEMPO 2SM BR (IFR) KPSF 19Z-22Z). OTHERWISE VFR
CIGS/VSBY WILL LIKELY TRANSITION TO MVFR AT THE REMAINING TAF
SITES...EXCEPT KPOU WHERE LESS IN THE WAY OF SHOWERS WILL MEAN A
CONTINUATION OF VFR INTO THE EVENING.
HOWEVER...AS HIGH DEWPOINTS WORK INTO THE REGION TONIGHT...EVERYONE
LOOKS TO DIP INTO THE MVFR THRESHOLD (LOW MVFR AT KALB) AND IFR
CONDITIONS AT KGFL...AFTER 00Z THIS EVENING. ONCE CONDITIONS
DROP...THEY MIGHT HANG AT THESE RESPECTIVE VALUES INTO AT LEAST
SATURDAY MORNING...POSSIBLY LONGER NORTH OF KPOU. A MILD BUT MOIST
SOUTHERLY FLOW WILL CONTINUE THROUGH THE PERIOD.
THE WIND WILL BE SOUTHERLY LESS THAN 10 KT THROUGH 12Z SATURDAY.
OUTLOOK...
SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA.
SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN.
TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE
WEEKEND...WHICH MEANS SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A
STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY
EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL
AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD
COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH.
BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM
TEMPERATURES...SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS
ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD
BE MELTED FROM ABOUT THE MOHAWK RIVER SOUTH. FURTHER NORTH...
TEMPERATURES MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW.
THE POTENTIAL IS THERE FOR 1-2.5 INCHES OF RAINFALL FROM ALBANY
NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESSER AMOUNTS OF
RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS.
WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 6 AM EST SATURDAY FOR NYZ042-043.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM/JPV
SHORT TERM...GJM
LONG TERM...JPV
AVIATION...JPV
HYDROLOGY...GJM/NAS
AREA FORECAST DISCUSSION
NWS TAUNTON MA
658 PM EST FRI DEC 20 2013
.SYNOPSIS...
ANOTHER ROUND OF SCATTERED SHOWERS IS EXPECTED OVERNIGHT...MAINLY
ALONG AND NORTH OF THE MA TURNPIKE. A FRONTAL BOUNDARY WILL
GENERALLY BE TO THE NORTH OF THE REGION THROUGH MONDAY. PERIODS OF
RAIN SHOWERS AND UNSEASONABLY MILD TEMPS ARE EXPECTED...ESPECIALLY LATE
SAT NIGHT INTO MON. MAINLY DRY AND MUCH COLDER WEATHER ARRIVES TUE
AND WED.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
7 PM UPDATE...
LATEST RADAR IMAGERY SHOWED A BLOSSOMING AREA OF RAIN SHOWERS
ACROSS UPSTATE NEW YORK. THIS A RESULT OF CONTINUED WARM ADVECTION
ALOFT. THE HRRR MODEL SEEMS TO HAVE A PRETTY GOOD HANDLE ON THIS
SITUATION AND EXPECT A ROUND OF SCATTERED RAIN SHOWERS...MAINLY
ALONG AND NORTH OF THE MA TURNPIKE LATER THIS EVENING AND INTO THE
OVERNIGHT HOURS. CERTAINLY NOT EXPECTING A WASHOUT IN THIS
REGION...JUST A PERIOD OF SOME SCATTERED RAIN SHOWERS.
LOW TEMPS WILL REMAIN ABOVE FREEZING TONIGHT WITH SOUTHWEST WINDS
AND A FAIR AMOUNT OF MID LEVEL CLOUDINESS AROUND THE REGION. THERE
IS A LOW PROBABILITY THAT TEMPS COULD TOUCH FREEZING ACROSS
PORTIONS OF NORTHWEST MA/SOUTHWEST NH. IF THIS OCCURS...MAY RESULT
IN A FEW PATCHES OF BLACK ICE BUT AGAIN ODDS FAVOR IT REMAINING
ABOVE FREEZING EVEN IN THIS REGION.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
SATURDAY INTO SATURDAY NIGHT...
ELONGATED BOUNDARY REMAINS OVER NORTHERN NEW ENGLAND TOMORROW AND
INTO TOMORROW NIGHT KEEPING MUCH OF THE REGION IN THE WARM SECTOR.
THIS COULD ALLOW FOR THE LOW CLOUDS TO REMAIN ACROSS THE REGION
TAMPERING WITH THE POTENTIAL WARM UP EXPECTED FOR TOMORROW.
ALTHOUGH LOW TO MID 50S IS NOT OUT OF THE QUESTION...IT IS
POSSIBLE THAT THIS COULD BE TO WARM IF THE LOW CLOUDS STAY PUT.
THE NEXT FORECASTER WILL NEED TO MONITOR THIS POTENTIAL.
ANOTHER WAVE OF LOW PRESSURE WILL MOVE ALONG THIS BOUNDARY SAT
AFTERNOON AND INTO THE OVERNIGHT HOURS. THIS WAVE WILL BE THE BEST
CHANCE FOR SOME ACCUMULATING PRECIP. TEMPS WILL REMAIN ABOVE
FREEZING OVERNIGHT AND WITH INCREASING DEWPOINTS EXPECT AREAS TO
WIDESPREAD FOG TO DEVELOP...WHICH COULD BE DENSE. MODELS ARE
INDICATING A COLD AIR DAMMING SIGNATURE ACROSS ME AND EASTERN
NH...WHICH COULD COULD DROP INTO SOUTHERN NEW HAMPSHIRE BY 12Z
SUNDAY. IF TEMPS DO DROP BELOW 32F THEN THERE IS THE POTENTIAL FOR
FREEZING RAIN ACROSS IMMEDIATE NORTHERN CHESHIRE AND HILLSBOROUGH
COUNTIES IN NH. THERE IS STILL A LOW CONFIDENCE FORECAST AND IT IS
ALL DEPENDS ON HOW FAR SOUTH THAT COLD AIR MOVES. WE WILL CONTINUE
TO WATCH THIS SIGNATURE AND THE THREATS THAT MAY PERTAIN TO IT.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
HIGHLIGHTS...
* LOW PROBABILITY FOR A PERIOD OF FREEZING RAIN IN SOUTHERN NH SUNDAY
* DENSE FOG A CONCERN ACROSS THE INTERIOR ON SUNDAY
* PERIODS OF RAIN SHOWERS SUN/MON WITH WELL ABOVE NORMAL TEMPS
* MUCH COLDER AND MAINLY DRY WEATHER TUE/WED
DETAILS...
SUNDAY...
LOW CONFIDENCE FORECAST CONTINUES IN REGARDS TO TEMPERATURES. LOW
PRESSURE WILL BE PASSING TO THE WEST OF OUR REGION...BRINGING VERY
WARM MID LEVEL AIR INTO NEW ENGLAND. HOWEVER...A LARGE SURFACE HIGH
STRETCHING ACROSS CENTRAL/EASTERN CANADA WILL SEND A SURGE OF
SHALLOW COLD AIR SOUTHWARD. THE MAIN CONCERN WILL BE IF TEMPS CAN
FALL TO OR JUST BELOW 32 DEGREES FOR A TIME ACROSS PORTIONS OF
SOUTHERN NH. MOST MODELS KEEP THAT JUST TO OUR NORTH...BUT GIVEN THE
STRENGTH OF THE HIGH AND SHALLOW COLD AIR...WOULD NOT BE IMPOSSIBLE
FOR THAT TO OCCUR FOR AT LEAST A TIME ACROSS SOUTHERN NH.
THEREFORE...THINK THERE REMAINS A LOW PROBABILITY FOR A PERIOD OF
FREEZING RAIN ACROSS PORTIONS OF SOUTHERN NH. THE SIGNIFICANT ICING
POTENTIAL LOOKS TO REMAIN TO OUR NORTH.
AS FOR PRECIP CHANCES...A STRONG LOW LEVEL JET IMPINGING ON THE
BOUNDARY WILL RESULT IN RAIN SHOWERS...WITH THE ACTIVITY BEING MOST
NUMEROUS TO THE NORTH OF ROUTE 2 IN THE VICINITY OF THE BOUNDARY. A
PERIOD OF HEAVY RAIN IS EVEN POSSIBLE ACROSS OUR FAR NORTHERN ZONES
...BUT SOUTH OF THE MA TURNPIKE JUST A FEW SHOWERS ARE EXPECTED
AND A FAIR AMOUNT OF THE DAY MAY END UP DRY.
THERE ALSO WILL BE A GOOD CHANCE FOR AREAS OF DENSE FOG ACROSS
INTERIOR SOUTHERN NEW ENGLAND. THIS A RESULT OF HIGH DEWPOINT AIR
OVER RUNNING THE DEEP SNOW PACK...SO A DENSE FOG ADVISORY MAY BE
NEEDED.
LASTLY...HIGH TEMP FORECASTS ON SUNDAY ARE OF VERY LOW CONFIDENCE.
AREAS SOUTH OF THE MA TURNPIKE SHOULD WARM SECTOR AND HIGHS WILL
PROBABLY EXCEED 60 DEGREES! IT MAY BE MUCH COOLER NORTH OF MA
TURNPIKE...ESPECIALLY IN FAR NORTHEAST MA/SOUTHEAST NH WHERE
BOUNDARY MAY NOT MIX OUT. WILL SHOW A LARGE GRADIENT IN EXPECTED
HIGH TEMPS ON SUNDAY...BUT LATER SHIFTS MAY CERTAINLY HAVE TO
REFINE.
SUNDAY NIGHT...
AN UNSEASONABLY MILD NIGHT IS ON TAP ACROSS SOUTHERN NEW ENGLAND
WITH SOUTHWEST FLOW OF VERY MILD AIR. PORTIONS OF THE REGION SOUTH
OF THE MA TURNPIKE PROBABLY WILL NOT DROP BELOW 50 DEGREES! A FEW
LEFT OVER SHOWERS ARE POSSIBLE...BUT MUCH OF THE NIGHT WILL PROBABLY
END UP DRY.
MONDAY AND MONDAY NIGHT...
A SECONDARY WAVE LOOKS TO MOVE UP THE COAST ON MON/MON NIGHT. A
PERIOD OF RAIN SHOWERS WILL BE POSSIBLE ACROSS THE ENTIRE
REGION...BUT HIGHEST PROBABILITIES WILL BE ACROSS EASTERN AND
SOUTHERN SECTIONS. TEMPS WILL STILL BE QUITE MILD ON
MONDAY...ESPECIALLY ACROSS SOUTHEAST NEW ENGLAND WHERE IT SHOULD
AGAIN REACH WELL INTO THE 50S. COLDER AIR WILL WORK IN BEHIND A
COLD FRONT LATE MON AND MON NIGHT. LOW PROBABILITY THAT RAIN COULD
END AS A VERY BRIEF PERIOD OF LIGHT SNOW OR FLURRIES.
TUESDAY AND WEDNESDAY...
MAINLY DRY AND VERY COLD WEATHER TUE/WED WITH BELOW NORMAL TEMPS.
LOW PROBABILITY OF SOME OCEAN EFFECT VERY LIGHT SNOW
SHOWERS/FLURRIES ACROSS PORTIONS OF THE CAPE/NANTUCKET TUE NIGHT/WED
AM WITH NNW WINDS...BUT NOTHING SIGNIFICANT EXPECTED.
THURSDAY AND FRIDAY...
LOW CONFIDENCE FORECAST OVER THIS TIME. TEMPERATURES SHOULD
MODERATE TO SOME DEGREE THU INTO EARLY FRI...BUT ANOTHER SHOT OF
COLDER AIR MAY FOLLOW LATE FRI. JUST INCLUDED A SLIGHT CHANCE POPS
THU NIGHT INTO FRI...GIVEN CONSIDERABLE MODEL DISAGREEMENT.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH SATURDAY NIGHT/...
TONIGHT...LOW CONFIDENCE. GUIDANCE SUGGESTS IFR TO LIFR
DEVELOPING ACROSS THE REGION IN LOW CLOUDS/FOG. GIVEN THAT THERE
ARE NOT ANY LOW CLOUDS OR FOG TO THE SOUTH OF OUR REGION...PLAYED
IT MORE OPTIMISTIC JUST TAKING THINGS DOWN TO MVFR FOR NOW.
CONFIDENCE IS LOW...SO LATER SHIFTS MAY HAVE TO MAKE CHANGES.
SATURDAY AND SATURDAY NIGHT...MODERATE CONFIDENCE.
MVFR CONDITIONS ON SATURDAY WILL DETERIORATE TO IFR AND LIFR
CONDITIONS SATURDAY NIGHT IN LOW CLOUDS/FOG. EXPECT SCT SHOWERS
CHANCE TO INCREASE NORTH OF THE MASS PIKE BY SAT NIGHT AND INTO
EARLY SUN MORNING. LOW PROBABILITY OF LIGHT FREEZING RAIN ACROSS
SOUTHERN NEW HAMPSHIRE OVERNIGHT SATURDAY INTO SUNDAY. O DENSE
FOG DEVELOPMENT IS LIKELY TO DEVELOP SAT NIGHT INTO SUNDAY.
KBOS TAF...LOW TO MODERATE CONFIDENCE IN TAF.
KBDL TAF...LOW TO MODERATE CONFIDENCE IN TAF.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
SUNDAY AND MONDAY...MODERATE CONFIDENCE. PERIODS OF MVFR-IFR
CONDITIONS IN MAINLY RAIN SHOWERS/LOW CLOUDS AND AREAS OF FOG. FOG
COULD BE DENSE AT TIMES ESPECIALLY ON SUNDAY...RESULTING IN EVEN
LIFR CONDITIONS.
TUESDAY AND WEDNESDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR
CONDITIONS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH SATURDAY NIGHT/...HIGH CONFIDENCE
SW FLOW WILL CONTINUE OVER THE WATERS THROUGH THE PERIOD. EXPECT
OCCASIONAL GUSTS ABOVE 25KTS ESP ACROSS THE OUTER WATERS THROUGH
THE WEEKEND. OTHERWISE SEAS WILL BE INCREASING FROM THE SW FETCH
THAT IS DEVELOPING. EXPECT 5FT ON THE NORTHEASTERN
OUTER WATERS ...BUT THE SOUTHERN WATERS WILL INCREASE TO AT LEAST
8FT. SCA HAS BEEN EXTENDED ACCORDINGLY. HAVE A LOW CONFIDENCE ON
WINDS ACROSS THE BAYS SO HAVE HELD OFF ISSUANCE FOR NOW.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
SUNDAY AND SUNDAY NIGHT...MODERATE CONFIDENCE. SOUTHWEST FLOW WILL
RESULT IN STRONG SCA WIND GUSTS AND HIGH SEAS ACROSS OUR SOUTHERN
WATERS. LOW PROBABILITY FOR A PERIOD OF GALES...BUT KEPT THINGS
BELOW FOR NOW WITH THE INVERSION OVER THE WATERS. ACROSS OUR NORTHERN
WATERS...LOW CONFIDENCE AS FRONT FROM THE NORTH MAY SWITCH WINDS TO
THE NORTH FOR A PERIOD OF TIME. UNCERTAIN HOW FAR SOUTH THIS FRONT
WILL GET.
MONDAY...MODERATE CONFIDENCE. WINDS DIMINISH BELOW SCA THRESHOLDS
AS PRESSURE GRADIENT WEAKENS. SEAS WILL DIMINISH BUT REMAIN ABOVE
SCA THRESHOLDS ACROSS THE OUTER ATLANTIC WATERS.
MONDAY NIGHT THROUGH TUESDAY NIGHT...MODERATE CONFIDENCE. COLD
FRONT CROSS THE REGION MON NIGHT SHIFTING THE WINDS TO NORTHWEST.
STRONG COLD ADVECTION SHOULD YIELD NORTHWEST SCA WIND GUSTS OF 25 TO
30 KNOTS OVER THE OPEN WATERS MOST OF THE TIME.
WEDNESDAY...MODERATE CONFIDENCE. WINDS AND SEAS SHOULD DROP BELOW
SCA THRESHOLDS DURING THE DAY AS STRONG HIGH PRESSURE BUILDS OVER
THE WATERS.
&&
.CLIMATE...
RECORD HIGHS FOR DECEMBER 22ND...
HARTFORD /BDL/ 59 DEGREES...1990
WORCESTER /ORH/ 63 DEGREES...1923
BOSTON /BOS/ 62 DEGREES...1990
PROVIDENCE /PVD/ 61 DEGREES...1990
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...AIR QUALITY ALERT UNTIL 11 PM EST SATURDAY FOR NHZ011.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR ANZ235-237-250-
254>256.
&&
$$
SYNOPSIS...DUNTEN/FRANK
NEAR TERM...FRANK
SHORT TERM...DUNTEN
LONG TERM...FRANK
AVIATION...FRANK/DUNTEN
MARINE...DUNTEN/FRANK
CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS TAUNTON MA
433 PM EST THU DEC 19 2013
.SYNOPSIS...
DRY WEATHER WILL CONTINUE TONIGHT AND INTO TOMORROW...ISOLATED
SHOWERS ARE POSSIBLE NORTH OF ROUTE 2. A COLD FRONT WILL STALL TO
OUR NORTH TOMORROW. THIS STALLED FRONT WILL RESULT IN PERIODS OF
UNSETTLED WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER
WEATHER ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
4 PM UPDATE...
FORECAST REMAINS ON TRACK FOR THIS AFTERNOON AS WINDS ARE
STARTING TO DIE DOWN AND TEMPS ARE DROPPING. LATEST SATELLITE
IMAGERY SHOWS CLOUDS WILL CONTINUE TO FILTER INTO THE REGION AND
BECOME MORE WIDESPREAD THIS EVENING.
TONIGHT...
STATIONARY BOUNDARY WILL SET UP ACROSS NORTHERN NEW ENGLAND
TONIGHT AS A RESULT OF AN APPROACHING LOW PRESSURE SYSTEM FROM THE
GREAT LAKES. THIS FRONT WILL ALLOW FOR PRECIP TO DEVELOP ALONG IT
OVERNIGHT AND INTO TOMORROW MORNING. LATEST GUIDANCE KEEPS THIS
FRONT FARTHER NORTH OF THE REGION. HI-RES GUIDANCE AND HRRR KEEP
ALL THE PRECIP NORTH OF THE REGION AS WELL. HOWEVER DID KEEP SOME
LINGERING POPS FOR THE EARLY MORNING HOURS. THIS MAY ALLOW FOR
SOME LIGHT FREEZING RAIN IN THE FAR NORTHERN PORTION OF
FRANKLIN...HILLSBOROUGH AND CHESHIRE COUNTIES. BUT BECAUSE OF THE
LOW CONFIDENCE AND THE FACT THAT HI-RES GUIDANCE KEEPS THIS
PORTION MAINLY DRY DID NOT ISSUE ANY HEADLINES AT THIS TIME.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
FRIDAY INTO FRIDAY NIGHT...
ABOVE AVERAGE TEMPERATURES WILL CONTINUE INTO FRIDAY HOWEVER BY
JUST A FEW DEGREES. INITIALLY THOUGHT THAT TEMPS TOMORROW WILL BE
WELL INTO THE 50S AS WE HIT THE MID 40S TODAY. YET LOOKING AT
SOUNDING DATA APPEARS THAT A SUBSTANCE INVERSION WILL BE SET UP
OVER THE REGION. SO WHILE 925 MB TEMPS WILL BE BETWEEN 7C TO
9C...WE MAY BE IN THE LOW TO UPPER 40S ACROSS THE AREA AT THE
SURFACE. THE MAX T GRID FOR TOMORROW MAY BE TO OPTIMISTIC. A STRAY
SHOWER OR TWO MAY MOVE ACROSS THE REGION TOMORROW AS THE BOUNDARY
BEGINS TO SLIDE SOUTHWARD...BUT OVERALL FEEL MAINLY DRY WEATHER
FOR TOMORROW ESPECIALLY SOUTH OF ROUTE 2.
THAT FRONT WILL SLIDE FARTHER SOUTH AND CLOSER TO THE NW COUNTIES ON
FRIDAY NIGHT INCREASING THE POTENTIAL FOR SOME PRECIP AS A LOW
PRESSURE MOVES ALONG THE BOUNDARY. SURFACE TEMPS WILL BE NEAR OR
ABOVE FREEZING FOR THIS TIMEFRAME SO THE POTENTIAL FOR ICING IS
LESS. THE HIGHEST LOCATION FOR PRECIP TO OCCURS WILL BE REGIONS
NORTH OF ROUTE 2 WITH AN ISOLATED CHANCE NORTH OF THE MASS PIKE.
TEMPERATURES OVERNIGHT WILL ONLY DROP SLIGHTLY AS OVERCAST SKIES AND
WEAK WAA WILL LIMIT RADIATIONAL COOLING.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
SATURDAY...COLD FRONT IS NEARLY STATIONARY ACROSS
NORTHERN/CENTRAL NEW ENGLAND EARLY IN THE DAY...WITH MODELS
INDICATING THIS FRONT WILL SLOWLY PUSH SOUTHWARD DURING THE DAY.
LIGHT RAIN SHOWERS POSSIBLE OVER SOUTHERN NH/NORTHERN MA IN THE
MORNING...WITH INCREASING CHANCES FOR RAIN SHOWERS TO THE SOUTH IN
THE AFTERNOON. QPF AMOUNTS EXPECTED TO BE LIGHT.
SATURDAY NIGHT...AGREEMENT BETWEEN THE GFS AND ECMWF THAT FRONT WILL
BECOME DRAPED IN THE VICINITY OF SOUTHERN NH/NORTHERN MA DURING THIS
TIMEFRAME. THERE IS STILL UNCERTAINTY REGARDING THE TEMPERATURE
PROFILE SATURDAY NIGHT AND SUNDAY...BUT THE TREND CONTINUES TO BE
KEEPING MOST OF THE CWA OUT OF THE MUCH COLDER TEMPERATURES AND
FREEZING RAIN. THE MAIN CONCERN AT THIS POINT IS SURFACE
TEMPERATURES IN THE FAR NORTHERN TIER OF THE FORECAST AREA...IN
PARTICULAR SOUTHERN NEW HAMPSHIRE. THERE IS A RISK FOR A PERIOD OF
FREEZING RAIN IN CHESHIRE AND HILLSBOROUGH COUNTIES LATE SATURDAY
NIGHT INTO SUNDAY MORNING...WITH A VERY LOW CHANCE OF FREEZING RAIN
DURING THIS TIMEFRAME OVER EXTREME NORTHERN MA.
SUNDAY...FRONT BEGINS TO PUSH NORTHWARD AS A WARM FRONT DURING THE
DAY...ANY FREEZING PRECIPITATION SHOULD CHANGE OVER TO RAIN SHOWERS
AS THE MORNING PROGRESSES. QPF TOTALS FOR SUNDAY ARE UNCERTAIN FOR
SOUTHERN NEW ENGLAND...EARLY INDICATIONS ARE 0.25 INCH TO AN
INCH...BUT IN ADDITION TO THIS RAIN THERE WILL BE SNOWMELT. ACROSS
MOST OF MASSACHUSETTS...AS WELL AS N CT AND RI...SURFACE DEWPOINTS
ARE EXPECTED TO CLIMB INTO THE 50S. HIGH TEMPERATURES MAY REACH MID
50S TO AROUND 60. THIS WITH A 10 TO 15 MPH SOUTHERLY SURFACE WIND
WILL PROMPT CONSIDERABLE SNOWMELT. THE SNOWMELT ALONG WITH
MODERATE QPF COULD CAUSE FLOODING IN LOW LYING AND POOR DRAINAGE
AREAS. ANY DRAINS THAT ARE SNOW CLOGGED COULD POSE A FLOOD RISK.
SUNDAY NIGHT THRU MONDAY...CONTINUED CHANCE FOR RAIN SHOWERS UNTIL
ARCTIC FRONT MOVES SOUTHEAST OF SOUTHERN NEW ENGLAND MONDAY. PRECIP
COULD END AS A BRIEF PERIOD OF SNOW SHOWERS.
MONDAY THROUGH CHRISTMAS DAY...WITH THE ARCTIC FRONT FINALLY MOVES
SOUTHEAST OF SOUTHERN NEW ENGLAND...MODELS CONTINUE TO INDICATE COLD
HIGH PRESSURE BUILDING IN BEHIND THE FRONT WITH SUBSTANTIALLY
COLDER TEMPERATURES FOR CHRISTMAS EVE AND DAY.
THURSDAY...MODELS ARE INDICATING POTENTIAL FOR APPROACH OF A COLD
FRONT FROM THE WEST...WITH SOMEWHAT MILDER AIR MOVING IN AHEAD OF
THE FRONT. WILL HAVE A CHANCE OF RAIN/SNOW SHOWERS LATE THURSDAY
AND THURSDAY NIGHT.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...
WINDS WILL DIE DOWN AFTER SUNSET. HIGH CONFIDENCE VFR
TONIGHT...WITH A LOW POTENTIAL FOR SOME MVFR CONDITIONS IN
SHOWERS AND POSSIBLE ICING ACROSS S NH.
FRIDAY AND FRIDAY NIGHT...
HIGH CONFIDENCE IN VFR TOMORROW WITH SOME SHOWERS APPROACHING THE
NW PORTION OF THE REGION BY LATE FRIDAY NIGHT. COULD BE SOME MVFR
MIXED IN WITH THE SHOWERS ESP ACROSS NORTHERN SITES.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH MONDAY MORNING...LOW CONFIDENCE. MVFR/IFR
CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN IS
POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
TUESDAY...HIGH CONFIDENCE VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE
SW WINDS ARE WEAKENING THIS EVENING AND INTO THE OVERNIGHT. SEAS
WILL ALSO BEGIN TO RELAX AS WELL. ALTERED SCA IN ACCORDANCES.
LIGHT SW FLOW WILL CONTINUE INTO TOMORROW BUT BEGIN TO PULSE UP BY
TOMORROW NIGHT. SEAS WILL LINGER AROUND 5 FT ESP ACROSS THE
SOUTHER OUTER WATERS TOMORROW AND INTO TOMORROW NIGHT...THEREFORE
HAVE EXTENDED THE SCA. DID UNDERCUT SEAS FOR FRIDAY NIGHT AS THEY
SEEMED VERY ROBUST IN A SW FLOW REGIME.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS 25 TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. SEAS MAY BUILD TO 7 TO 10 FEET ON THE OUTER WATERS
DURING SUN AND SUN NIGHT. MUCH OF THIS TIME WILL LIKELY NEED SMALL
CRAFT ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL
CONFIDENCE IS LOW ON TIMING.
&&
.CLIMATE...
RECORD HIGHS FOR DECEMBER 22ND...
HARTFORD /BDL/ 59 DEGREES...1990
WORCESTER /ORH/ 63 DEGREES...1923
BOSTON /BOS/ 62 DEGREES...1990
PROVIDENCE /PVD/ 61 DEGREES...1990
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN/NMB
LONG TERM...NMB
AVIATION...DUNTEN/NMB
MARINE...DUNTEN/NMB
CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS TAUNTON MA
427 PM EST THU DEC 19 2013
.SYNOPSIS...
DRY WEATHER WILL CONTINUE TONIGHT AND INTO TOMORROW...ISOLATED
SHOWERS ARE POSSIBLE NORTH OF ROUTE 2. A COLD FRONT WILL STALL TO
OUR NORTH TOMORROW. THIS STALLED FRONT WILL RESULT IN PERIODS OF
UNSETTLED WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER
WEATHER ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
4 PM UPDATE...
FORECAST REMAINS ON TRACK FOR THIS AFTERNOON AS WINDS ARE
STARTING TO DIE DOWN AND TEMPS ARE DROPPING. LATEST SATELLITE
IMAGERY SHOWS CLOUDS WILL CONTINUE TO FILTER INTO THE REGION AND
BECOME MORE WIDESPREAD THIS EVENING.
TONIGHT...
STATIONARY BOUNDARY WILL SET UP ACROSS NORTHERN NEW ENGLAND
TONIGHT AS A RESULT OF AN APPROACHING LOW PRESSURE SYSTEM FROM THE
GREAT LAKES. THIS FRONT WILL ALLOW FOR PRECIP TO DEVELOP ALONG IT
OVERNIGHT AND INTO TOMORROW MORNING. LATEST GUIDANCE KEEPS THIS
FRONT FARTHER NORTH OF THE REGION. HI-RES GUIDANCE AND HRRR KEEP
ALL THE PRECIP NORTH OF THE REGION AS WELL. HOWEVER DID KEEP SOME
LINGERING POPS FOR THE EARLY MORNING HOURS. THIS MAY ALLOW FOR
SOME LIGHT FREEZING RAIN IN THE FAR NORTHERN PORTION OF
FRANKLIN...HILLSBOROUGH AND CHESHIRE COUNTIES. BUT BECAUSE OF THE
LOW CONFIDENCE AND THE FACT THAT HI-RES GUIDANCE KEEPS THIS
PORTION MAINLY DRY DID NOT ISSUE ANY HEADLINES AT THIS TIME.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
FRIDAY INTO FRIDAY NIGHT...
ABOVE AVERAGE TEMPERATURES WILL CONTINUE INTO FRIDAY HOWEVER BY
JUST A FEW DEGREES. INITIALLY THOUGHT THAT TEMPS TOMORROW WILL BE
WELL INTO THE 50S AS WE HIT THE MID 40S TODAY. YET LOOKING AT
SOUNDING DATA APPEARS THAT A SUBSTANCE INVERSION WILL BE SET UP
OVER THE REGION. SO WHILE 925 MB TEMPS WILL BE BETWEEN 7C TO
9C...WE MAY BE IN THE LOW TO UPPER 40S ACROSS THE AREA AT THE
SURFACE. THE MAX T GRID FOR TOMORROW MAY BE TO OPTIMISTIC. A STRAY
SHOWER OR TWO MAY MOVE ACROSS THE REGION TOMORROW AS THE BOUNDARY
BEGINS TO SLIDE SOUTHWARD...BUT OVERALL FEEL MAINLY DRY WEATHER
FOR TOMORROW ESPECIALLY SOUTH OF ROUTE 2.
THAT FRONT WILL SLIDE FARTHER SOUTH AND CLOSER TO THE NW COUNTIES ON
FRIDAY NIGHT INCREASING THE POTENTIAL FOR SOME PRECIP AS A LOW
PRESSURE MOVES ALONG THE BOUNDARY. SURFACE TEMPS WILL BE NEAR OR
ABOVE FREEZING FOR THIS TIMEFRAME SO THE POTENTIAL FOR ICING IS
LESS. THE HIGHEST LOCATION FOR PRECIP TO OCCURS WILL BE REGIONS
NORTH OF ROUTE 2 WITH AN ISOLATED CHANCE NORTH OF THE MASS PIKE.
TEMPERATURES OVERNIGHT WILL ONLY DROP SLIGHTLY AS OVERCAST SKIES AND
WEAK WAA WILL LIMIT RADIATIONAL COOLING.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
SATURDAY...COLD FRONT IS NEARLY STATIONARY ACROSS
NORTHERN/CENTRAL NEW ENGLAND EARLY IN THE DAY...WITH MODELS
INDICATING THIS FRONT WILL SLOWLY PUSH SOUTHWARD DURING THE DAY.
LIGHT RAIN SHOWERS POSSIBLE OVER SOUTHERN NH/NORTHERN MA IN THE
MORNING...WITH INCREASING CHANCES FOR RAIN SHOWERS TO THE SOUTH IN
THE AFTERNOON. QPF AMOUNTS EXPECTED TO BE LIGHT.
SATURDAY NIGHT...AGREEMENT BETWEEN THE GFS AND ECMWF THAT FRONT WILL
BECOME DRAPED IN THE VICINITY OF SOUTHERN NH/NORTHERN MA DURING THIS
TIMEFRAME. THERE IS STILL UNCERTAINTY REGARDING THE TEMPERATURE
PROFILE SATURDAY NIGHT AND SUNDAY...BUT THE TREND CONTINUES TO BE
KEEPING MOST OF THE CWA OUT OF THE MUCH COLDER TEMPERATURES AND
FREEZING RAIN. THE MAIN CONCERN AT THIS POINT IS SURFACE
TEMPERATURES IN THE FAR NORTHERN TIER OF THE FORECAST AREA...IN
PARTICULAR SOUTHERN NEW HAMPSHIRE. THERE IS A RISK FOR A PERIOD OF
FREEZING RAIN IN CHESHIRE AND HILLSBOROUGH COUNTIES LATE SATURDAY
NIGHT INTO SUNDAY MORNING...WITH A VERY LOW CHANCE OF FREEZING RAIN
DURING THIS TIMEFRAME OVER EXTREME NORTHERN MA.
SUNDAY...FRONT BEGINS TO PUSH NORTHWARD AS A WARM FRONT DURING THE
DAY...ANY FREEZING PRECIPITATION SHOULD CHANGE OVER TO RAIN SHOWERS
AS THE MORNING PROGRESSES. QPF TOTALS FOR SUNDAY ARE UNCERTAIN FOR
SOUTHERN NEW ENGLAND...EARLY INDICATIONS ARE 0.25 INCH TO AN
INCH...BUT IN ADDITION TO THIS RAIN THERE WILL BE SNOWMELT. ACROSS
MOST OF MASSACHUSETTS...AS WELL AS N CT AND RI...SURFACE DEWPOINTS
ARE EXPECTED TO CLIMB INTO THE 50S. HIGH TEMPERATURES MAY REACH MID
50S TO AROUND 60. THIS WITH A 10 TO 15 MPH SOUTHERLY SURFACE WIND
WILL PROMPT CONSIDERABLE SNOWMELT. THE SNOWMELT ALONG WITH
MODERATE QPF COULD CAUSE FLOODING IN LOW LYING AND POOR DRAINAGE
AREAS. ANY DRAINS THAT ARE SNOW CLOGGED COULD POSE A FLOOD RISK.
SUNDAY NIGHT THRU MONDAY...CONTINUED CHANCE FOR RAIN SHOWERS UNTIL
ARCTIC FRONT MOVES SOUTHEAST OF SOUTHERN NEW ENGLAND MONDAY. PRECIP
COULD END AS A BRIEF PERIOD OF SNOW SHOWERS.
MONDAY THROUGH CHRISTMAS DAY...WITH THE ARCTIC FRONT FINALLY MOVES
SOUTHEAST OF SOUTHERN NEW ENGLAND...MODELS CONTINUE TO INDICATE COLD
HIGH PRESSURE BUILDING IN BEHIND THE FRONT WITH SUBSTANTIALLY
COLDER TEMPERATURES FOR CHRISTMAS EVE AND DAY.
THURSDAY...MODELS ARE INDICATING POTENTIAL FOR APPROACH OF A COLD
FRONT FROM THE WEST...WITH SOMEWHAT MILDER AIR MOVING IN AHEAD OF
THE FRONT. WILL HAVE A CHANCE OF RAIN/SNOW SHOWERS LATE THURSDAY
AND THURSDAY NIGHT.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...
WINDS WILL DIE DOWN AFTER SUNSET. HIGH CONFIDENCE VFR
TONIGHT...WITH A LOW POTENTIAL FOR SOME MVFR CONDITIONS IN
SHOWERS AND POSSIBLE ICING ACROSS S NH.
FRIDAY AND FRIDAY NIGHT...
HIGH CONFIDENCE IN VFR TOMORROW WITH SOME SHOWERS APPROACHING THE
NW PORTION OF THE REGION BY LATE FRIDAY NIGHT. COULD BE SOME MVFR
MIXED IN WITH THE SHOWERS ESP ACROSS NORTHERN SITES.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH MONDAY MORNING...LOW CONFIDENCE. MVFR/IFR
CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN IS
POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
TUESDAY...HIGH CONFIDENCE VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE
SW WINDS ARE WEAKENING THIS EVENING AND INTO THE OVERNIGHT. SEAS
WILL ALSO BEGIN TO RELAX AS WELL. ALTERED SCA IN ACCORDANCES.
LIGHT SW FLOW WILL CONTINUE INTO TOMORROW BUT BEGIN TO PULSE UP BY
TOMORROW NIGHT. SEAS WILL LINGER AROUND 5 FT ESP ACROSS THE
SOUTHER OUTER WATERS TOMORROW AND INTO TOMORROW NIGHT...THEREFORE
HAVE EXTENDED THE SCA. DID UNDERCUT SEAS FOR FRIDAY NIGHT AS THEY
SEEMED VERY ROBUST IN A SW FLOW REGIME.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS 25 TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. SEAS MAY BUILD TO 7 TO 10 FEET ON THE OUTER WATERS
DURING SUN AND SUN NIGHT. MUCH OF THIS TIME WILL LIKELY NEED SMALL
CRAFT ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL
CONFIDENCE IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN/NMB
LONG TERM...NMB
AVIATION...DUNTEN/NMB
MARINE...DUNTEN/NMB
AREA FORECAST DISCUSSION
NWS TAUNTON MA
358 PM EST THU DEC 19 2013
.SYNOPSIS...
DRY WEATHER WILL CONTINUE TONIGHT AND INTO TOMORROW...ISOLATED
SHOWERS ARE POSSIBLE NORTH OF ROUTE 2. A COLD FRONT WILL STALL TO
OUR NORTH TOMORROW. THIS STALLED FRONT WILL RESULT IN PERIODS OF
UNSETTLED WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER
WEATHER ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
4 PM UPDATE...
FORECAST REMAINS ON TRACK FOR THIS AFTERNOON AS WINDS ARE
STARTING TO DIE DOWN AND TEMPS ARE DROPPING. LATEST SATELLITE
IMAGERY SHOWS CLOUDS WILL CONTINUE TO FILTER INTO THE REGION AND
BECOME MORE WIDESPREAD THIS EVENING.
TONIGHT...
STATIONARY BOUNDARY WILL SET UP ACROSS NORTHERN NEW ENGLAND
TONIGHT AS A RESULT OF AN APPROACHING LOW PRESSURE SYSTEM FROM THE
GREAT LAKES. THIS FRONT WILL ALLOW FOR PRECIP TO DEVELOP ALONG IT
OVERNIGHT AND INTO TOMORROW MORNING. LATEST GUIDANCE KEEPS THIS
FRONT FARTHER NORTH OF THE REGION. HI-RES GUIDANCE AND HRRR KEEP
ALL THE PRECIP NORTH OF THE REGION AS WELL. HOWEVER DID KEEP SOME
LINGERING POPS FOR THE EARLY MORNING HOURS. THIS MAY ALLOW FOR
SOME LIGHT FREEZING RAIN IN THE FAR NORTHERN PORTION OF
FRANKLIN...HILLSBOROUGH AND CHESHIRE COUNTIES. BUT BECAUSE OF THE
LOW CONFIDENCE AND THE FACT THAT HI-RES GUIDANCE KEEPS THIS
PORTION MAINLY DRY DID NOT ISSUE ANY HEADLINES AT THIS TIME.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
FRIDAY INTO FRIDAY NIGHT...
ABOVE AVERAGE TEMPERATURES WILL CONTINUE INTO FRIDAY HOWEVER BY
JUST A FEW DEGREES. INITIALLY THOUGHT THAT TEMPS TOMORROW WILL BE
WELL INTO THE 50S AS WE HIT THE MID 40S TODAY. YET LOOKING AT
SOUNDING DATA APPEARS THAT A SUBSTANCE INVERSION WILL BE SET UP
OVER THE REGION. SO WHILE 925 MB TEMPS WILL BE BETWEEN 7C TO
9C...WE MAY BE IN THE LOW TO UPPER 40S ACROSS THE AREA AT THE
SURFACE. THE MAX T GRID FOR TOMORROW MAY BE TO OPTIMISTIC. A STRAY
SHOWER OR TWO MAY MOVE ACROSS THE REGION TOMORROW AS THE BOUNDARY
BEGINS TO SLIDE SOUTHWARD...BUT OVERALL FEEL MAINLY DRY WEATHER
FOR TOMORROW ESPECIALLY SOUTH OF ROUTE 2.
THAT FRONT WILL SLIDE FARTHER SOUTH AND CLOSER TO THE NW COUNTIES ON
FRIDAY NIGHT INCREASING THE POTENTIAL FOR SOME PRECIP AS A LOW
PRESSURE MOVES ALONG THE BOUNDARY. SURFACE TEMPS WILL BE NEAR OR
ABOVE FREEZING FOR THIS TIMEFRAME SO THE POTENTIAL FOR ICING IS
LESS. THE HIGHEST LOCATION FOR PRECIP TO OCCURS WILL BE REGIONS
NORTH OF ROUTE 2 WITH AN ISOLATED CHANCE NORTH OF THE MASS PIKE.
TEMPERATURES OVERNIGHT WILL ONLY DROP SLIGHTLY AS OVERCAST SKIES AND
WEAK WAA WILL LIMIT RADIATIONAL COOLING.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...
WINDS WILL DIE DOWN AFTER SUNSET. HIGH CONFIDENCE VFR
TONIGHT...WITH A LOW POTENTIAL FOR SOME MVFR CONDITIONS IN
SHOWERS AND POSSIBLE ICING ACROSS S NH.
FRIDAY AND FRIDAY NIGHT...
HIGH CONFIDENCE IN VFR TOMORROW WITH SOME SHOWERS APPROACHING THE
NW PORTION OF THE REGION BY LATE FRIDAY NIGHT. COULD BE SOME MVFR
MIXED IN WITH THE SHOWERS ESP ACROSS NORTHERN SITES.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH MONDAY...
SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE
SW WINDS ARE WEAKENING THIS EVENING AND INTO THE OVERNIGHT. SEAS
WILL ALSO BEGIN TO RELAX AS WELL. ALTERED SCA IN ACCORDANCES.
LIGHT SW FLOW WILL CONTINUE INTO TOMORROW BUT BEGIN TO PULSE UP BY
TOMORROW NIGHT. SEAS WILL LINGER AROUND 5 FT ESP ACROSS THE
SOUTHER OUTER WATERS TOMORROW AND INTO TOMORROW NIGHT...THEREFORE
HAVE EXTENDED THE SCA. DID UNDERCUT SEAS FOR FRIDAY NIGHT AS THEY
SEEMED VERY ROBUST IN A SW FLOW REGIME.
OUTLOOK...SATURDAY THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN
LONG TERM...RLG
AVIATION...DUNTEN/RLG
MARINE...DUNTEN/RLG
AREA FORECAST DISCUSSION
NWS TAUNTON MA
700 AM EST THU DEC 19 2013
.SYNOPSIS...
DRY AND MILDER WEATHER EXPECTED TODAY AS A COLD FRONT STALLS TO
OUR NORTH. THIS STALLED FRONT WILL RESULT IN PERIODS OF UNSETTLED
WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER WEATHER
ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 AM UPDATE...MADE VERY FEW CHANGES TO THE FORECAST AND THOSE TO
THE SKY GRIDS TO BETTER MATCH SATELLITE TRENDS. OTHERWISE...THE
FORECAST IS ON TRACK.
PREVIOUS DISCUSSION...
FOR THE REST OF TODAY...EXPECTING A DRY DAY WITH A HIGH PRESSURE
LOCATED ALONG THE SOUTHEAST USA COAST. THIS WILL RESULT IN A WEST
TO SOUTHWEST FLOW TODAY.
3.9 MICRON SATELLITE IMAGERY SHOWING ABUNDANT LOW-LEVEL MOISTURE
STREAMING EAST FROM THE GREAT LAKES THIS MORNING. THESE CLOUDS
HAVE SINCE COVERED MOST OF SOUTHERN NEW ENGLAND. WEST FLOW...
ALBEIT RELATIVELY LIGHT...THIS MORNING WILL INDUCE SOME
DOWNSLOPING. THUS THINKING THERE SHOULD BE MORE SUN THAN CLOUDS
TODAY...ONCE THE CURRENT CLOUDS IN OUR REGION MOVE EAST. THE
LATEST VERSION OF THE RAP SEEMED TO BE HANDLING THIS SITUATION
WELL...SO RELIED ON IT FOR TIMING.
IT WILL BE A LITTLE WARMER TODAY THAN YESTERDAY WITH THE SUNSHINE
AND WEST TO SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
A FRONTAL BOUNDARY WILL SLOWLY MOVE SOUTH THROUGH NORTHERN NEW
ENGLAND TONIGHT. THERE IS STILL SOME QUESTION AS TO EXACTLY HOW
MUCH PROGRESS IT WILL MAKE IN OUR DIRECTION. DEEPER MOISTURE STILL
SHOULD REMAIN NORTH OF OUR REGION FOR MOST OF TONIGHT. SO ONLY
HAVE A CHANCE OF SOME SOME PRECIPITATION VERY LATE TONIGHT INTO
FRIDAY NORTH OF I-90...MAINLY DURING THE DAYTIME FRIDAY.
THE TIMING OF THIS FRONT AND PRECIPITATION WILL BE CRUCIAL FOR
DETERMINING TYPE. THINKING THERE IS A POSSIBILITY FOR SOME LIGHT
ICING ACROSS SOUTHERN NH LATE TONIGHT...BUT IT SHOULD NOT BE VERY
WIDESPREAD. AS SUCH...HOLDING OFF ON ISSUING ANY FREEZING RAIN
ADVISORIES AT THIS TIME. NEXT SHIFT WILL HAVE TO MONITOR THIS
SITUATION. EVENTUALLY ANY PRECIPITATION IN OUR REGION SHOULD
TRANSITION TO ALL RAIN AS TEMPERATURES CONTINUE TO RISE FRIDAY
MORNING. WARMING TREND CONTINUES...WITH HIGHS GENERALLY IN THE 40S
FOR THE FIRST TIME IN SEVERAL DAYS FOR MOST OF THE INTERIOR.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS FOR MUCH OF THE REGION TODAY.
MODERATE CONFIDENCE VFR TONIGHT...WITH THE POTENTIAL FOR SOME
MVFR CONDITIONS IN SHOWERS. ISOLATED POCKETS OF ICING POSSIBLE
NORTH OF KLWM-KFIT-KORE-KAQW. GUSTY SW WIND GUSTS UP TO 30 KT
DEVELOPING AT KACK BY LATE MORNING.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...HIGH CONFIDENCE
ANOTHER PULSE OF STRONG SW WINDS WILL DEVELOP LATER TODAY. NEAR
GALE FORCE GUSTS POSSIBLE OVER THE OUTER SOUTH COASTAL WATERS.
CONFIDENCE IN A PROLONGED PERIOD OF GALE FORCE GUSTS IS MODERATE
AT BEST. WINDS WILL DIMINISH TONIGHT AS PRESSURE GRADIENT
RELAXES. DECIDED TO REPLACE THE GALE WATCH WITH A HIGH END SMALL
CRAFT ADVISORY.
LATEST WNA WAVE HEIGHT GUIDANCE LOOKS SLIGHTLY UNDERDONE. WILL
MAKE SOME TWEAKS IN THE NEAR TERM TO BRING SEAS UP TO LATEST
MARINE REPORTS.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ230-
236.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/RLG
NEAR TERM...BELK/RLG
SHORT TERM...BELK
LONG TERM...RLG
AVIATION...BELK/RLG
MARINE...BELK/RLG
AREA FORECAST DISCUSSION
NWS TAUNTON MA
604 AM EST THU DEC 19 2013
.SYNOPSIS...
DRY AND MILDER WEATHER EXPECTED TODAY AS A COLD FRONT STALLS TO
OUR NORTH. THIS STALLED FRONT WILL RESULT IN PERIODS OF UNSETTLED
WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER WEATHER
ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
415 AM UPDATE...MADE SOME TWEAKS TO SKY COVER BASED ON OBSERVED
TRENDS. TWEAKED TEMPERATURES BASED ON THE CLOUDS ALREADY IN
PLACE...AS MOST LOCATIONS INDICATING A REBOUND FROM THEIR
RESPECTIVE MIN TEMPERATURES AS THE CLOUDS ARRIVE.
FOR THE REST OF TODAY...EXPECTING A DRY DAY WITH A HIGH PRESSURE
LOCATED ALONG THE SOUTHEAST USA COAST. THIS WILL RESULT IN A WEST
TO SOUTHWEST FLOW TODAY.
3.9 MICRON SATELLITE IMAGERY SHOWING ABUNDANT LOW-LEVEL MOISTURE
STREAMING EAST FROM THE GREAT LAKES THIS MORNING. THESE CLOUDS
HAVE SINCE COVERED MOST OF SOUTHERN NEW ENGLAND. WEST FLOW...
ALBEIT RELATIVELY LIGHT...THIS MORNING WILL INDUCE SOME
DOWNSLOPING. THUS THINKING THERE SHOULD BE MORE SUN THAN CLOUDS
TODAY...ONCE THE CURRENT CLOUDS IN OUR REGION MOVE EAST. THE
LATEST VERSION OF THE RAP SEEMED TO BE HANDLING THIS SITUATION
WELL...SO RELIED ON IT FOR TIMING.
IT WILL BE A LITTLE WARMER TODAY THAN YESTERDAY WITH THE SUNSHINE
AND WEST TO SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
A FRONTAL BOUNDARY WILL SLOWLY MOVE SOUTH THROUGH NORTHERN NEW
ENGLAND TONIGHT. THERE IS STILL SOME QUESTION AS TO EXACTLY HOW
MUCH PROGRESS IT WILL MAKE IN OUR DIRECTION. DEEPER MOISTURE STILL
SHOULD REMAIN NORTH OF OUR REGION FOR MOST OF TONIGHT. SO ONLY
HAVE A CHANCE OF SOME SOME PRECIPITATION VERY LATE TONIGHT INTO
FRIDAY NORTH OF I-90...MAINLY DURING THE DAYTIME FRIDAY.
THE TIMING OF THIS FRONT AND PRECIPITATION WILL BE CRUCIAL FOR
DETERMINING TYPE. THINKING THERE IS A POSSIBILITY FOR SOME LIGHT
ICING ACROSS SOUTHERN NH LATE TONIGHT...BUT IT SHOULD NOT BE VERY
WIDESPREAD. AS SUCH...HOLDING OFF ON ISSUING ANY FREEZING RAIN
ADVISORIES AT THIS TIME. NEXT SHIFT WILL HAVE TO MONITOR THIS
SITUATION. EVENTUALLY ANY PRECIPITATION IN OUR REGION SHOULD
TRANSITION TO ALL RAIN AS TEMPERATURES CONTINUE TO RISE FRIDAY
MORNING. WARMING TREND CONTINUES...WITH HIGHS GENERALLY IN THE 40S
FOR THE FIRST TIME IN SEVERAL DAYS FOR MOST OF THE INTERIOR.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /11Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS FOR MUCH OF THE REGION TODAY.
MODERATE CONFIDENCE VFR TONIGHT...WITH THE POTENTIAL FOR SOME
MVFR CONDITIONS IN SHOWERS. ISOLATED POCKETS OF ICING POSSIBLE
NORTH OF KLWM-KFIT-KORE-KAQW. GUSTY SW WIND GUSTS UP TO 30 KT
DEVELOPING AT KACK BY LATE MORNING.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...HIGH CONFIDENCE
ANOTHER PULSE OF STRONG SW WINDS WILL DEVELOP LATER TODAY. NEAR
GALE FORCE GUSTS POSSIBLE OVER THE OUTER SOUTH COASTAL WATERS.
CONFIDENCE IN A PROLONGED PERIOD OF GALE FORCE GUSTS IS MODERATE
AT BEST. WINDS WILL DIMINISH TONIGHT AS PRESSURE GRADIENT
RELAXES. DECIDED TO REPLACE THE GALE WATCH WITH A HIGH END SMALL
CRAFT ADVISORY.
LATEST WNA WAVE HEIGHT GUIDANCE LOOKS SLIGHTLY UNDERDONE. WILL
MAKE SOME TWEAKS IN THE NEAR TERM TO BRING SEAS UP TO LATEST
MARINE REPORTS.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ230-
236.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/RLG
NEAR TERM...BELK
SHORT TERM...BELK
LONG TERM...RLG
AVIATION...BELK/RLG
MARINE...BELK/RLG
AREA FORECAST DISCUSSION
NWS TAUNTON MA
430 AM EST THU DEC 19 2013
.SYNOPSIS...
DRY AND MILDER WEATHER EXPECTED TODAY AS A COLD FRONT STALLS TO
OUR NORTH. THIS STALLED FRONT WILL RESULT IN PERIODS OF UNSETTLED
WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER WEATHER
ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
415 AM UPDATE...MADE SOME TWEAKS TO SKY COVER BASED ON OBSERVED
TRENDS. TWEAKED TEMPERATURES BASED ON THE CLOUDS ALREADY IN
PLACE...AS MOST LOCATIONS INDICATING A REBOUND FROM THEIR
RESPECTIVE MIN TEMPERATURES AS THE CLOUDS ARRIVE.
FOR THE REST OF TODAY...EXPECTING A DRY DAY WITH A HIGH PRESSURE
LOCATED ALONG THE SOUTHEAST USA COAST. THIS WILL RESULT IN A WEST
TO SOUTHWEST FLOW TODAY.
3.9 MICRON SATELLITE IMAGERY SHOWING ABUNDANT LOW-LEVEL MOISTURE
STREAMING EAST FROM THE GREAT LAKES THIS MORNING. THESE CLOUDS
HAVE SINCE COVERED MOST OF SOUTHERN NEW ENGLAND. WEST FLOW...
ALBEIT RELATIVELY LIGHT...THIS MORNING WILL INDUCE SOME
DOWNSLOPING. THUS THINKING THERE SHOULD BE MORE SUN THAN CLOUDS
TODAY...ONCE THE CURRENT CLOUDS IN OUR REGION MOVE EAST. THE
LATEST VERSION OF THE RAP SEEMED TO BE HANDLING THIS SITUATION
WELL...SO RELIED ON IT FOR TIMING.
IT WILL BE A LITTLE WARMER TODAY THAN YESTERDAY WITH THE SUNSHINE
AND WEST TO SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
A FRONTAL BOUNDARY WILL SLOWLY MOVE SOUTH THROUGH NORTHERN NEW
ENGLAND TONIGHT. THERE IS STILL SOME QUESTION AS TO EXACTLY HOW
MUCH PROGRESS IT WILL MAKE IN OUR DIRECTION. DEEPER MOISTURE STILL
SHOULD REMAIN NORTH OF OUR REGION FOR MOST OF TONIGHT. SO ONLY
HAVE A CHANCE OF SOME SOME PRECIPITATION VERY LATE TONIGHT INTO
FRIDAY NORTH OF I-90...MAINLY DURING THE DAYTIME FRIDAY.
THE TIMING OF THIS FRONT AND PRECIPITATION WILL BE CRUCIAL FOR
DETERMINING TYPE. THINKING THERE IS A POSSIBILITY FOR SOME LIGHT
ICING ACROSS SOUTHERN NH LATE TONIGHT...BUT IT SHOULD NOT BE VERY
WIDESPREAD. AS SUCH...HOLDING OFF ON ISSUING ANY FREEZING RAIN
ADVISORIES AT THIS TIME. NEXT SHIFT WILL HAVE TO MONITOR THIS
SITUATION. EVENTUALLY ANY PRECIPITATION IN OUR REGION SHOULD
TRANSITION TO ALL RAIN AS TEMPERATURES CONTINUE TO RISE FRIDAY
MORNING. WARMING TREND CONTINUES...WITH HIGHS GENERALLY IN THE 40S
FOR THE FIRST TIME IN SEVERAL DAYS FOR MOST OF THE INTERIOR.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS FOR MUCH OF THE REGION TODAY.
SOME MVFR CIGS WILL AFFECT THE E SLOPES OF THE BERKSHIRES THIS
MORNING. MODERATE CONFIDENCE VFR TONIGHT...WITH THE POTENTIAL FOR
SOME MVFR CONDITIONS IN SHOWERS. ISOLATED POCKETS OF ICING
POSSIBLE NORTH OF KLWM-KFIT-KORE-KAQW. GUSTY SW WIND GUSTS UP TO
30 KT DEVELOPING AT KACK BY LATE MORNING.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...HIGH CONFIDENCE
ANOTHER PULSE OF STRONG SW WINDS WILL DEVELOP LATER TODAY. NEAR
GALE FORCE GUSTS POSSIBLE OVER THE OUTER SOUTH COASTAL WATERS.
CONFIDENCE IN A PROLONGED PERIOD OF GALE FORCE GUSTS IS MODERATE
AT BEST. WINDS WILL DIMINISH TONIGHT AS PRESSURE GRADIENT
RELAXES. DECIDED TO REPLACE THE GALE WATCH WITH A HIGH END SMALL
CRAFT ADVISORY.
LATEST WNA WAVE HEIGHT GUIDANCE LOOKS SLIGHTLY UNDERDONE. WILL
MAKE SOME TWEAKS IN THE NEAR TERM TO BRING SEAS UP TO LATEST
MARINE REPORTS.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 5 PM EST THIS
AFTERNOON FOR ANZ230-236.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/RLG
NEAR TERM...BELK
SHORT TERM...BELK
LONG TERM...RLG
AVIATION...BELK/RLG
MARINE...BELK/RLG
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
856 PM EST FRI DEC 20 2013
.UPDATE...
EVENING SURFACE ANALYSIS DEPICTS THE AXIS OF ATLANTIC RIDGING
BISECTING OUR AREA...WHILE A COLD FRONT WAS POSITIONED FROM THE
GREAT LAKES STATES SOUTHWESTWARD INTO THE ARKLATEX REGION.
ALOFT...ROBUST RIDGING WAS CENTERED OVER SOUTH FLORIDA AND THE
BAHAMAS. A POTENT SHORTWAVE...LOCATED AT THE BASE OF DEEP
TROUGHING OVER THE WESTERN UNITED STATES...WAS MOVING ACROSS THE
DESERT SOUTHWEST. A DECK OF CIRRUS WAS SPILLING OVER THE PERIPHERY
OF THE SOUTH FL RIDGE THIS EVENING...AND WILL SOON BLANKET
SOUTHEAST GA. LOW AND MID LEVEL CLOUDS OVER THE EASTERN GULF OF
MEXICO WERE ERODING AS THEY ADVECT INLAND OVER THE FL BIG BEND AND
NATURE COAST...AND FAIR SKIES PREVAIL OVER MOST OF NORTHEAST AND
NORTH CENTRAL FL. TEMPERATURES WERE GENERALLY FALLING INTO THE
UPPER 50S AND LOWER 60S...AND DEWPOINTS CONTINUE TO SLOWLY
CLIMB...AND ARE NOW IN THE MID AND UPPER 50S.
MODEL SOUNDINGS PROJECT INCREASING SOUTHEAST TO SOUTHERLY LOW-
LEVEL WIND SPEEDS TONIGHT...WITH 500-1000 FT SPEEDS INCREASING TO
15-20 KTS TOWARDS DAWN. THIS...COUPLED WITH AN INCREASE IN HIGH
ALTITUDE CLOUDINESS FROM THE WEST...SHOULD PRECLUDE WIDESPREAD
DENSE FOG FORMATION OVERNIGHT DESPITE UNSEASONABLY HIGH MOISTURE
VALUES. WE DO EXPECT LOW CEILINGS TO ADVECT NORTHEASTWARD FROM THE
GULF OVERNIGHT...ESPECIALLY ACROSS NORTH CENTRAL AND PORTIONS OF
NORTHEAST FL. RIDGING ALOFT SHOULD KEEP ANY ISOLATED SHOWER
ACTIVITY LOCATED WELL TO THE WEST OF OUR REGION. LOWS TONIGHT WILL
AVERAGE ABOUT 5 DEGREES ABOVE LATE DECEMBER CLIMO...GENERALLY
55-60 DEGREES. RIDGING WILL CONTINUE TO AMPLIFY LOCALLY ON
SATURDAY AS THE POTENT SHORTWAVE EJECTS NORTHEASTWARD INTO THE
SOUTHERN PLAINS STATES. PATCHY MORNING FOG SHOULD DISSIPATE
SHORTLY AFTER SUNRISE...SETTING THE STAGE FOR NEAR RECORD WARMTH
REGION-WIDE ON SATURDAY AFTERNOON. A FEW SHOWERS ARE POSSIBLE OVER
FAR WESTERN AND NORTHERN SECTIONS OF OUR AREA DURING THE LATE
AFTERNOON HOURS.
RECORD HIGHS THIS WEEKEND:
SAT SUN
--- ---
JACKSONVILLE 81(1951) 82(1967)
GAINESVILLE 85(1931) 82(2011)
ALMA 80(1988) 81(2011)
ST SIMONS 76(2008) 82(1970)
&&
.AVIATION...MAY SEE TEMPO MVFR CONDS OCCUR LATE TONIGHT IN PATCHY
FOG BETWEEN 9-13Z ESPECIALLY AT KCRG REDUCING TO VSBY TO LESS THAN 2
MILES. HIGHER CIRROFORM CLOUDS SHOULD PRECLUDE WIDESPREAD DENSER
FOG. VFR CONDS GENERALLY EXPECTED BETWEEN 13-15Z THRU THE REMAINDER
OF THE TAF PERIOD.
&&
.MARINE...
A SOUTHEASTERLY WIND SURGE WILL SPREAD NORTHWARD AS THE EVENING
PROGRESSES...WITH SPEEDS OFFSHORE APPROACHING 15 KNOTS. SWELL
DOMINATED SEAS WILL AVERAGE 2 TO 3 FEET NEARSHORE AND 3 TO 5 FEET
OFFSHORE. SOUTHERLY WINDS ARE EXPECTED TO REACH CAUTION
CRITERIA...15-20 KTS...BY SATURDAY EVENING OVER THE OFFSHORE
WATERS. EVENING WIND SURGES ON SATURDAY AND SUNDAY NIGHTS WILL
BRING WIND SPEEDS IN THE NEARSHORE WATERS TO NEAR CAUTION
CRITERIA. SEA FOG IS ALSO EXPECTED TO DEVELOP ON SATURDAY
EVENING...ESPECIALLY OVER THE NEARSHORE GA WATERS. A COLD FRONT
WILL MOVE INTO THE COASTAL WATERS ON MON EVENING...ACCOMPANIED BY
NUMEROUS SHOWERS AND A FEW EMBEDDED THUNDERSTORMS. NORTHERLY WINDS
IN THE WAKE OF THE FRONT WILL QUICKLY INCREASE TO SMALL CRAFT
ADVISORY CRITERIA TOWARDS DAWN ON TUES IN THE OFFSHORE WATERS.
SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED THROUGHOUT THE
COASTAL WATERS FOR TUE/WED...AS OFFSHORE SEAS BUILD TO 7-10 FT.
RIP CURRENTS: A LINGERING LONG-PERIOD EASTERLY SWELL WILL
KEEP A MODERATE RISK IN PLACE THROUGH SATURDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 57 81 61 82 / 10 10 20 30
SSI 58 74 62 77 / 0 0 10 20
JAX 59 82 62 83 / 0 0 10 10
SGJ 61 79 65 82 / 0 0 10 10
GNV 58 84 62 84 / 10 10 10 10
OCF 59 85 62 85 / 10 10 10 10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&
$$
NELSON/CORDERO/GUILLET
[top]
Area Forecast Discussion
National Weather Service Tallahassee FL
815 PM EST Fri Dec 20 2013
.Near Term [Tonight]...
The 21 UTC regional surface analysis showed our forecast area
under the western periphery of a high pressure system that was
retreating into the Atlantic. There was a cold front in MO and AR,
which will be affecting our local weather on Sunday. There aren`t
many surface reports in the eastern Gulf of Mexico, and the most
recent ASCAT pass was blank in this region, but satellite imagery
showed a weak disturbance approaching our forecast area from the
south. There were even a few deep showers (with sheared cloud
tops) earlier this afternoon, however they have since weakened.
Some of the Convection Allowing Models generate scattered showers
over our forecast area overnight with this system, but they often
over-do convection with these types of cool season, shallow
systems. The 00 UTC KTAE sounding still showed some very dry
layers aloft, which is probably helping to account for the
apparent weakening trend on satellite imagery. This system may
become a developing warm front by early Saturday, as it moves
quickly northward during the day. Our PoP overnight is 10%, which
is in line dry GFS and ECMWF MOS. The very wet NAM MOS has been
discounted. The increase in mid layer clouds, shallow moisture
profile, and non-zero surface wind speeds should limit the fog
potential. Lows will be in the mid to upper 50s.
&&
.Aviation...
[Through 00Z Saturday] Very tricky and tenuous Taf fcst tonight
as there are major discrepancies in the expected conditions
between the numerical and Hi-Res guidance for the overnight and
morning hours on Saturday. With the HRRR and the NARRE in good
agreement, used past experience and forecaster judgment of good
results in these cases and leaned heavily in this direction.
Therefore, kept most locations at MVFR levels for several hours
late tonight into Saturday, and also delayed the onset of the
worsening conditions. Did bring ECP to the precipice of IFR
conditions and would not be surprised if they are reached there at
some point, but for now, the only terminal with great enough
confidence for IFR levels was DHN, where IFR Cigs and Vis were
fcst. Should the numerical guidance be correct, however, ALL of
the terminals would fall to LIFR levels which does not seem likely
at this point, especially given the increasing VFR cloudiness this
evening from the south and the west. On Saturday, the MVFR
conditions may be a bit slow to break, but once the gusty S winds
take over (likely by late morning), VFR conditions should return
to all locations.
&&
.Prev Discussions [253 PM EST]...
.Short Term [Saturday Through Sunday Night]...
A front will approach the area on Sunday morning with southerly flow
pulling warmer temperatures and dewpoints northward over our CWA.
Expect temperatures near 80 with dewpoints in the upper 60s. The
airmass will be marginally unstable on Sunday, expected CAPE values
will generally be between 400-800 J/Kg with some patches above 1000
J/Kg. 0-6 km shear will range between 40 and 60 kts which could aid
in the development of isolated severe storms out ahead of or within
the main line.
.Long Term [Monday Through Friday]...
Showers and thunderstorms will remain in the area Sunday night
and into Monday. Seasonable but cooler air moves in behind the
front on Tuesday and Wednesday. A return to near climo temps for the
end of the period. The Christmas forecast will be pleasant with
highs in the mid 60s and lows in the 40s. A chance for PoP (20-30%)
returns to the forecast by Thursday and Friday as moisture moves
back in from the southeast.
.Marine...
Light southeasterly winds will continue today and begin to
increase tonight. By Saturday morning winds will reach cautionary
levels and could possibly reach advisory criteria during the
frontal passage on Sunday. Behind the front northwest winds
increase and by Tuesday advisory winds and seas will return.
.Fire Weather...
Unseasonably warm and humid conditions are expected across the
Tri-State Area during the next few days, with increasing rain
chances on Sunday and Monday as well. This will keep afternoon
relative humidities well above Red Flag Levels.
.Hydrology...
Area river guages remain below action stage. The next chance for
significant rainfall is Sunday with totals averaging one to two
inches.
&&
.Preliminary Point Temps/PoPs...
Tallahassee 58 80 64 78 66 / 10 10 10 30 40
Panama City 62 77 70 78 65 / 10 10 20 50 50
Dothan 58 78 69 78 61 / 10 10 30 50 60
Albany 56 80 65 80 63 / 10 10 20 40 50
Valdosta 58 82 64 80 64 / 10 10 10 20 30
Cross City 58 82 62 82 63 / 10 0 10 10 20
Apalachicola 63 74 67 75 67 / 10 10 10 30 40
&&
.TAE Watches/Warnings/Advisories...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
Near Term...Gould
Short Term...Fournier
Long Term...Moore/Walsh
Aviation...Gould
Marine...Fournier
Fire Weather...Gould
Hydrology...Weston
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
215 PM EST THU DEC 19 2013
...WARMER TEMPERATURES ON THE WAY FOR THE UPCOMING WEEKEND...
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN UPPER LEVEL PATTERN
CHARACTERIZED BY DEEP LONGWAVE TROUGHING DIGGING DOWN THE PACIFIC
COAST AND THROUGH THE INTER-MOUNTAIN WEST...FOLLOWED DOWNSTREAM BY A
MORE ZONAL FLOW PATTERN OVER THE CENTRAL AND EASTERN CONUS. THIS
ZONAL FLOW PATTERN EXTENDS SOUTH TO INCLUDE THE NORTHERN GULF OF
MEXICO COAST AND FLORIDA PENINSULA. WV IMAGERY SHOWS A LARGE SWATH
OF VERY DRY AIR IN THE MID/UPPER LEVELS OF THE TROP COVERING THE
FLORIDA PENINSULA AND THE 18/12Z KTBW SOUNDING PROFILE SHOWS THAT
THIS DRY AIR EXTENDS DOWN INTO THE NEAR SURFACE LAYERS AS WELL. THE
KTBW SOUNDING PROFILE FROM THIS MORNING SHOWS AN IMPRESSIVE PW VALUE
OF ONLY AROUND 0.27". THIS VALUE IS NEARLY 2 STANDARD DEVIATIONS
BELOW CLIMATOLOGY FOR THE MIDDLE OF DECEMBER. WITH ALL THE DRY AIR
OVER OUR HEADS...IT IS LITTLE WONDER THAT WE ARE EXPERIENCING MOSTLY
SUNNY SKIES TODAY.
AT THE SURFACE...OUR REGIONS RESIDES TO THE SOUTH OF A 1028MB HIGH
PRESSURE RIDGE CENTERED OVER GA/CAROLINAS. THE GRADIENT IS NOT VERY
STRONG RESULTING IN A WEAK EASTERLY FLOW ACROSS THE PENINSULA.
TEMPERATURES HAVE RECOVERED NICELY FROM THE COOL EARLY MORNING AND
ARE NOW IN THE LOW/MID 70S NORTH ZONES AND MID/UPPER 70S SOUTH.
&&
.SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...
TONIGHT...NOT ANTICIPATING ANY ADDITIONAL FROST CONCERNS FOR THE
NATURE COAST. WILL BE ANOTHER COOL NIGHT...BUT NOT NEARLY AS COOL AS
WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. COOLEST TEMPERATURES
DOWN POTENTIALLY TO THE LOWER/MID 40S WILL BE FOUND ACROSS THE
NORTHERN NATURE COAST...WITH LOWER TO MIDDLE 50S CENTRAL AND MIDDLE
TO UPPER 50S FAR SOUTH.
.FRIDAY AND FRIDAY NIGHT...
THE WARM UP CONTINUES AS THE ZONAL FLOW TRANSITIONS TO UPPER LEVEL
RIDGING OVER THE FL PENINSULA IN PARTIAL RESPONSE TO DIGGING UPPER
TROUGH AND HEIGHT FALLS APPROACHING THE SOUTHERN PLAINS. SURFACE
RIDGE EXITS OFF INTO THE WESTERN ATLANTIC...ALLOWING OUR GRADIENT TO
TIGHTEN SLIGHTLY AND WINDS TO SHIFT FROM EASTERLY TO SOUTHEASTERLY.
THIS SOUTHEASTERLY FLOW WILL BEGIN TO BRING A MORE SIGNIFICANT LOW
LEVEL MOISTURE RETURN TO THE REGION. THE TIGHTER GRADIENT WILL ALLOW
FOR MORE EFFICIENT DIURNAL MIXING AND WITH 850MB TEMPS OF 14-15C
OVERHEAD...DAYTIME TEMPS WILL RISE INTO THE MID/UPPER 70S FAR
NORTH...AND APPROACH OR SURPASS 80 BY A FEW DEGREES FROM THE I-4
CORRIDOR SOUTHWARD. EVEN THROUGH THE GRADIENT WILL BE A BIT
TIGHTER ON FRIDAY...THE STRONGER TERRESTRIAL HEATING MAY ALLOW FOR A
FEEBLE SEA-BREEZE TO DEVELOP. THIS SEA-BREEZE ALONG WITH SOME
MOISTURE RETURN...MAY BE ENOUGH TO FORCE A FEW SHALLOW
SEA-BREEZE/INSTABILITY SHOWERS DURING THE AFTERNOON...MAINLY I-4 AND
SOUTHWARD. IN FACT...SEVERAL OF THE LOCAL HI-RES GUIDANCE MEMBERS
ARE DEVELOPING A FEW "SPOTTY" SHOWERS WITHIN THIS REGIME AND SO WILL
ADD A SLIGHT CHANCE 20% POP TO THE FORECAST FROM HILLSBOROUGH/POLK
COUNTY SOUTHWARD FOR THE AFTERNOON. REGARDLESS...EVEN IF A FEW
SHOWERS DEVELOP...THEY WILL BE BRIEF AND HAVE VERY LIMITED IMPACT TO
ANY OUTDOOR ACTIVITIES. THE ADDED LOW LEVEL MOISTURE WILL RESULT IN
A MUCH WARMER OVERNIGHT FRIDAY NIGHT INTO SATURDAY MORNING WITH MOST
LOCATIONS FAILING TO FALL OUT OF THE 60S...WITH THE EXCEPTION OF
MID/UPPER 50S INLAND TO THE NORTH OF BROOKSVILLE.
SATURDAY AND SATURDAY NIGHT...
MID/UPPER LEVEL RIDGING WILL HOLD ON TO ITS INFLUENCE OVER THE
PENINSULA AS TROUGHING AND ASSOCIATED SURFACE LOW PRESSURE ADVANCE
INTO THE CENTRAL PLAINS/MS VALLEY. THIS INCLEMENT WEATHER WILL NOT
BE IN OUR FORECAST AS THE PROTECTION OF THE UPPER RIDGE KEEPS OUR
WEATHER GENERALLY DRY AND UNSEASONABLY WARM. ALL THE SYNOPTIC
FORCING FOR LIFT AND DEEP LAYER MOISTURE IS STILL WELL REMOVED FROM
OUR REGION THROUGH SATURDAY NIGHT...SO LOOK FOR FAIR CONDITIONS TO
CONTINUE AND TEMPS TO CONTINUE WARMING. HIGHS SATURDAY AFTERNOON
SHOULD REACH THE LOWER 80S FOR MUCH OF THE AREA WITH WARMER SPOTS
FROM TAMPA SOUTHWARD TO FORT MYERS HAVING POTENTIAL TO HIT MID 80S.
LOWS SATURDAY NIGHT HOLD IN THE 60S FOR ALL.
&&
.LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)...
MODEL GUIDANCE TRENDING MORE IN AGREEMENT WITH THE NEXT SYSTEM TO
DEVELOP OVER THE SOUTHERN PLAINS SATURDAY NIGHT AS AN UPPER LOW
BECOMES NEGATIVELY TILTED OVER THE TX/OK BORDER AND EJECTS OVER
THE SOUTHERN GREAT LAKES ON SUNDAY. MEANWHILE A DEEPENING SURFACE
LOW PRESSURE SYSTEM WILL STRENGTHEN THE SOUTH/SOUTHEAST FLOW OVER
THE EASTERN GULF WATERS SATURDAY NIGHT INTO EARLY SUNDAY AS A COLD
FRONT APPROACHES THE FLORIDA PANHANDLE SUNDAY NIGHT. THE TIMING OF
THE FRONT AND ASSOCIATED RAINFALL CHANCES HAS BEEN PUSHED FORWARD
BY ABOUT 6 HOURS WITH THE LATEST FORECAST PLACING EARLY MONDAY
THROUGH MONDAY NIGHT AS THE PRIMARY WINDOW OF OPPORTUNITY FOR ANY
MEASURABLE RAINFALL TO OCCUR ACROSS THE FORECAST AREA AS THE
SYSTEM PUSHES FROM NORTHWEST TO SOUTHEAST OVER THE PENINSULA.
SOUTHWEST MID TO UPPER FLOW BEHIND THE FRONT WILL PRODUCE SOME
ISENTROPIC UPGLIDE FOR CLOUDINESS AND LINGERING SHOWERS ON
TUESDAY. A BRIEF DECREASE IN CLOUD COVER EXPECTED ON CHRISTMAS DAY
AHEAD OF YET ANOTHER FAST MOVING FRONTAL SYSTEM AND UPPER TROUGH
LATER IN THE WEEK ALTHOUGH MOISTURE DEPTH WILL BE RATHER LIMITED.
&&
.AVIATION...
CLEAR SKIES PERSIST ACROSS THE REGION AS HIGH PRESSURE OVER THE
SOUTHEAST U.S. INFLUENCES THE WEATHER OVER FLORIDA. VFR CONDITIONS
WILL CONTINUE WITH THE EXCEPTION OF MVFR VISIBILITY RESTRICTIONS AT
LAL AND PGD FROM 09Z THROUGH 14Z WITH 4 MILES IN MIST. WINDS WILL
REMAIN LIGHT OUT OF THE EAST NORTHEAST...THEN VEERING TO THE
SOUTHEAST BY THIS EVENING AND INTO FRIDAY.
&&
.MARINE...
HIGH PRESSURE WILL SHIFT EASTWARD INTO THE ATLANTIC THROUGH FRIDAY
ALLOWING WINDS OVER THE EASTERN GULF TO SHIFT FROM EASTERLY TO
SOUTHEASTERLY. A PERIOD OF NEAR CAUTIONARY LEVEL WINDS IS POSSIBLE
TONIGHT OVER THE OFFSHORE WATERS BEFORE DIMINISHING BACK BELOW
HEADLINE CRITERIA DURING FRIDAY. ANOTHER PERIOD OF CAUTIONARY LEVEL
WINDS IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A SLOW MOVING
COLD FRONT WILL APPROACH THE EASTERN GULF DURING THE SECOND HALF OF
THE WEEKEND...BUT LIKELY NOT PASS THROUGH THESE WATERS UNTIL THE
EARLY PORTION OF NEXT WEEK.
&&
.FIRE WEATHER...
LOW LEVEL MOISTURE WILL INCREASE OVER THE NEXT COUPLE OF DAYS
KEEPING RELATIVE HUMIDITY ABOVE CRITICAL LEVELS. RAIN CHANCES WILL
REMAIN LOW THROUGH SATURDAY WITH TEMPERATURES WARMING BACK TO ABOVE
NORMAL LEVELS. PATCHY FOG WILL BE POSSIBLE BOTH TONIGHT AND FRIDAY
NIGHT...HOWEVER AT THIS TIME NO SIGNIFICANT AREAS OF DENSE FOG ARE
IN THE FORECAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 59 81 66 82 / 0 20 10 10
FMY 61 83 65 83 / 0 20 10 10
GIF 55 80 61 82 / 0 20 10 10
SRQ 59 81 65 83 / 0 20 10 10
BKV 49 81 62 83 / 0 10 10 10
SPG 62 79 67 80 / 0 20 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...WYNN
LONG TERM...LAMARRE
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
920 AM EST THU DEC 19 2013
...WARMER TEMPERATURES ON THE WAY FOR THE UPCOMING WEEKEND...
.UPDATE...
14Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN UPPER LEVEL PATTERN
CHARACTERIZED BY DEEP LONGWAVE TROUGHING DIGGING DOWN THE PACIFIC
COAST AND THROUGH THE INTER-MOUNTAIN WEST...FOLLOWED DOWNSTREAM BY A
MORE ZONAL FLOW PATTERN OVER THE CENTRAL AND EASTERN CONUS. THIS
ZONAL FLOW PATTERN EXTENDS SOUTH TO INCLUDE THE NORTHERN GULF OF
MEXICO COAST AND FLORIDA PENINSULA. WV IMAGERY SHOWS A LARGE SWATH
OF VERY DRY AIR IN THE MID/UPPER LEVELS OF THE TROP COVERING THE
FLORIDA PENINSULA AND THE 18/12Z KTBW SOUNDING PROFILE SHOWS THAT
THIS DRY AIR EXTENDS DOWN INTO THE NEAR SURFACE LAYERS AS WELL. THE
KTBW SOUNDING PROFILE FROM THIS MORNING SHOWS AN IMPRESSIVE PW VALUE
OF ONLY AROUND 0.27". THIS VALUE IS NEARLY 2 STANDARD DEVIATIONS
BELOW CLIMATOLOGY FOR THE MIDDLE OF DECEMBER. WITH ALL THE DRY AIR
OVER OUR HEADS...IT IS LITTLE WONDER THAT WE ARE EXPERIENCING
"CRYSTAL CLEAR" SKIES THIS MORNING AND NEAR 100% OF THE POSSIBLE
SUNSHINE.
AT THE SURFACE...OUR REGIONS RESIDES TO THE SOUTH OF A 1028MB HIGH
PRESSURE RIDGE CENTERED OVER GA/CAROLINAS. THE GRADIENT IS NOT VERY
STRONG RESULTING IN A WEAK EASTERLY FLOW ACROSS THE PENINSULA.
TEMPERATURES WERE QUITE COOL AROUND SUNRISE WITH SOME NEAR FREEZING
TEMPS UP TOWARD LEVY COUNTY...BUT ALREADY SEEING A RAPID RECOVERY OF
THESE TEMPERATURES WITH A COUPLE HOURS OF SUN NOW IN THE BOOKS.
THE REST OF TODAY AND TONIGHT...
A VERY DRY COLUMN ALOFT AND LITTLE IN THE WAY OF MOISTURE ADVECTION
OR SYNOPTIC SUPPORT FOR LIFT WILL KEEP OUR WEATHER FAIR...DRY AND
SEASONABLE. MAY SEE A FEW CUMULUS DEVELOP FOR THE AFTERNOON...BUT
WITH LITTLE MOISTURE TO WORK WITH AND ONLY A LIMITED INCREASE IN LOW
LEVEL ATLANTIC MOISTURE...OUR SKIES SHOULD REMAIN MOSTLY SUNNY
THROUGH THE DAY. TEMPERATURES WILL RISE INTO THE LOWER 70S
NORTH...MID 70S CENTRAL/I-4 CORRIDOR...AND MID/UPPER 70S SOUTH FOR
THE AFTERNOON HOURS. WINDS MAY GO VARIABLE ALONG THE COAST DURING
THE AFTERNOON AS A FEEBLE SEA-BREEZE TRIES TO DEVELOP...BUT THE LACK
OF STRONG INLAND HEATING AND SOME STRONGER FLOW JUST ABOVE THE
SURFACE...SHOULD KEEP ANY CIRCULATION CONFINED TO THE BEACHES OR
POTENTIALLY JUST OFFSHORE.
OVERNIGHT...NOT ANTICIPATING ANY ADDITIONAL FROST CONCERNS FOR THE
NATURE COAST. WILL BE ANOTHER COOL NIGHT...BUT NOT NEARLY AS COOL AS
WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. COOLEST TEMPERATURES
DOWN POTENTIALLY TO THE LOWER 40S WILL BE FOUND ACROSS THE NORTHERN
NATURE COAST...WITH LOWER TO MIDDLE 50S CENTRAL AND MIDDLE TO UPPER
50S FAR SOUTH.
MORE GENERALLY FAIR WEATHER WITH INCREASINGLY ABOVE NORMAL
TEMPERATURES WILL CONTINUE INTO FRIDAY AND SATURDAY. ENJOY THE REST
OF YOUR THURSDAY!
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS.
SURFACE HIGH PRESSURE SITUATED OVER THE SOUTHEAST U.S. THIS MORNING
WILL MOVE OFFSHORE THIS AFTERNOON AND TONIGHT. WINDS WILL REMAIN
LIGHT OUT OF THE EAST NORTHEAST...THEN VEERING TO THE SOUTHEAST BY
THIS EVENING AND INTO FRIDAY.
&&
.MARINE...
EASTERLY WINDS TODAY WILL TURN MORE TO THE SOUTHEAST FOR FRIDAY
AND INTO THE WEEKEND. WIND SPEEDS WILL INCREASE SOME ON SATURDAY
AND THEN WILL LIKELY REACH CAUTIONARY OR EVEN ADVISORY LEVELS
SATURDAY NIGHT INTO SUNDAY AS A FRONT APPROACHES THE WATERS.
SPEEDS RELAX SOME SUNDAY INTO MONDAY AND THEN TURN NORTHEASTERLY
BEHIND THE FRONT WITH SPEEDS INCREASING AGAIN ONCE THE FRONT
MOVES THROUGH THE WATERS. HAZARDOUS CONDITIONS LOOK TO CONTINUE
THROUGH AROUND MID-WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 75 59 80 67 / 0 10 10 10
FMY 78 60 84 67 / 0 10 20 10
GIF 76 57 82 64 / 0 10 10 10
SRQ 76 58 81 66 / 0 10 10 10
BKV 75 48 80 60 / 0 10 10 10
SPG 73 62 78 67 / 0 10 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...WYNN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
850 PM CST FRI DEC 20 2013
.DISCUSSION...
744 PM CST
THE FREEZING RAIN ADVISORY FOR NORTH CENTRAL AND EXTREME
NORTHEAST ILLINOIS WAS ALLOWED TO EXPIRE. FREEZING RAIN HAD
DIMINISHED TO FREEZING DRIZZLE EARLY THIS EVENING AND HAS NOW
ENDED ACROSS MOST OF THE ADVISORY AREA. THERE MAY BE A LINGERING
PATCH OR TWO OF FREEZING DRIZZLE BUT THOSE TOO ARE EXPECTED TO
END VERY SHORTLY. RADARS AT MKX...DVN AND ARX HAVE ALL SHOWN A W
TO E CLEARING OF THE WEAK ECHOES WHILE AN AREA OF WEAK ECHOES
ASSOCIATED WITH SOME DRIZZLE AND LIGHT RAIN HAD BLOSSOMED
OVERHEAD BUT IS STEADILY MOVING TO THE E SO THIS PRECIP IS
EXPECTED TO END 9PM CST AS THE TAIL END OF THE LATEST MINOR SHORT
WAVE TROUGH MOVES E OF THE AREA. FORTUNATELY WHERE THIS PRECIP IS
OCCURRING SURFACE TEMPERATURES ARE ABOVE FREEZING.
THE LAKE AND PORTER INDIANA COUNTIES PORTION OF THE DENSE FOG
ADVISORY ALSO WAS ALLOWED TO EXPIRE AS THE FRONTAL BOUNDARY HAD
DRIFTED SLIGHTLY SOUTHWARD ALLOWING WINDS TO BECOME LIGHT
NORTHWEST AND VISIBILITIES TO IMPROVER ABOVE DENSE FOG CRITERIA.
THE REMAINDER OF THE DENSE FOG ADVISORY HAS BEEN EXTENDED UNTIL
9 PM CST. THE WEAK SURFACE REFLECTION OF THE SHORT WAVE WAS IN THE
VPZ-SBN AREA. AS IT CONTINUES SLOWLY TO THE E THE REST OF THE
EVENING THE FRONTAL BOUNDARY WILL CONTINUE TO SAG DEEPER INTO THE
AREA THAT REMAINS UNDER THE ADVISORY WITH AN THINNING OF THE DENSE
FOG EXPECTED TO OCCUR.
TRS
//PREV DISCUSSION...
337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW...
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
DISCUSSION ON WINTER STORM.
WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND
CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES.
THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR
THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A
NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND
MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY
NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS
NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER
AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS.
THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH
TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY
NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS
FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY
SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION
ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL
LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH
SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT
TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR
ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL
LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING
AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE
COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS
OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET
IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER
NORTHWEST TRACK...I CHOOSE TO HOLD OFF.
THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET
ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING
AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN
RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS
MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING
SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF
SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF
I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE
CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY
RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING
THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE
EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE
AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN
AN SPS.
IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY
SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH.
STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY
PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND
WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE
EXPECTED.
THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR
TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW
ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS
THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY
LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS.
TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET
CLOSE TO CHICAGO AND INTERSTATE 80.
MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT
PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL
DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS
IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER
REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA.
KJB
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* IFR/LIFR CIG/VIS CONDITIONS TONIGHT WITH SOME LINGERING PATCHY
DRIZZLE. MAY IMPROVE TO LOW-END MVFR CIG EARLY SATURDAY MORNING
BEFORE LOWERING TO IFR AGAIN DURING THE DAY.
* TIMING/TYPE OF ONSET OF PRECIP SATURDAY.
RATZER
//DISCUSSION...UPDATED 00Z...
SURFACE LOW PRESSURE WAS LIFTING NORTHEAST ACROSS NORTHERN INDIANA
AT 23Z...ALONG FRONT WHICH HAD BECOME STATIONARY JUST TO THE SOUTH
OF THE TERMINALS. THE LOW WILL CONTINUE TO TRACK OFF TO THE EAST
TONIGHT...ALLOWING LOW LEVEL WINDS TO GRADUALLY BACK FROM
NORTHEAST TO NORTHWEST BEYOND MID-EVENING. EXTENSIVE AREA OF
IFR CEILINGS AND 2-5SM VISIBILITY FOG WAS OCCURRING IN VERY MOIST
LOW LEVEL ENVIRONMENT IN THE VICINITY OF THE LOW AND STALLED
FRONT. SOME IMPROVEMENT MAY OCCUR LATE TONIGHT WITH LOW LEVEL
NORTHWEST WINDS EVENTUALLY DRAWING COOLER/DRIER AIR IN FROM
AREAS NORTH/NORTHWEST OF THE TERMINALS...THOUGH CEILINGS REMAIN
BELOW 1000 FT AGL ACROSS MUCH OF SOUTHERN WI AND WITH RELATIVELY
LIGHT WINDS OVERNIGHT EXPECT IFR CONDITIONS TO LINGER FOR SOME
TIME. PATCHY LIFR CONDITIONS WITH LINGERING PATCHY DRIZZLE AND
FREEZING DRIZZLE SHOULD IMPROVE LATER THIS EVENING HOWEVER AS
FRONTAL ZONE DRIFTS TO THE SOUTHEAST.
ATTENTION THEN TURNS TO STORM SYSTEM LIFTING OUT OF THE SOUTHERN
PLAINS AND AFFECTING THE LOCAL AREA SATURDAY AFTERNOON THROUGH
SUNDAY. WINDS ARE EXPECTED TO SHIFT BACK TO THE NORTHEAST BY MID-
MORNING SATURDAY AND INCREASE INTO THE 10-15 KT RANGE LATER IN THE
DAY AS SURFACE LOW PRESSURE MOVES OUT OF TEXAS AND TOWARD THE
BOOTHEEL OF MISSOURI BY EVENING. PRECIPITATION IS EXPECTED TO
DEVELOP NORTHWARD INTO THE CHICAGO TERMINAL AREA BY MID-
AFTERNOON...WITH FORECAST THERMAL PROFILES INDICATING
PRECIPITATION WILL BE A MIX OF SNOW...SLEET AND RAIN OR FREEZING
RAIN. SURFACE TEMPERATURES ARE EXPECTED TO BE RIGHT AROUND THE
FREEZING MARK...POSSIBLY JUST ABOVE FREEZING. THERE COULD BE A
PERIOD OF FREEZING DRIZZLE OR DRIZZLE BY MID-LATE MORNING AS LIFT
BEGINS TO DEVELOP AHEAD OF THE SYSTEM ATOP MOIST LOW LEVELS.
CEILINGS THEN EXPECTED TO DROP BACK SOLIDLY INTO IFR WITH ONSET OF
PRECIP.
MIXED SLEET/RAIN/FREEZING EXPECTED TO CONTINUE SATURDAY EVENING...
EVENTUALLY CHANGING TO ALL SNOW BEYOND THE END OF THE TAF PERIOD
SOMETIME EARLY SUNDAY MORNING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN IFR CONDITIONS THROUGH MUCH OF TONIGHT WITH
VIS IMPROVING TO MVFR/VFR AS PATCHY DRIZZLE ENDS LATE EVENING.
* LOW CONFIDENCE IN CEILING TRENDS SATURDAY.
* MEDIUM CONFIDENCE IN PRECIP ONSET TIME AND PRECIP TYPE SATURDAY
AFTERNOON.
* MEDIUM CONFIDENCE IN CEILINGS DETERIORATING INTO IFR BY LATE
SATURDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...SNOW ESPECIALLY IN THE MORNING. IFR LIKELY. BRIEF LIFR
POSSIBLE EARLY.
MONDAY...CHANCE OF SNOW SHOWERS. MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...CHANCE OF LIGHT SNOW. MVFR/IFR POSSIBLE.
THURSDAY...SLIGHT CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
RATZER
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 10 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM
SUNDAY.
IN...DENSE FOG ADVISORY...INZ010-INZ011-INZ019 UNTIL 10 PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 PM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
745 PM CST FRI DEC 20 2013
.DISCUSSION...
744 PM CST
THE FREEZING RAIN ADVISORY FOR NORTH CENTRAL AND EXTREME
NORTHEAST ILLINOIS WAS ALLOWED TO EXPIRE. FREEZING RAIN HAD
DIMINISHED TO FREEZING DRIZZLE EARLY THIS EVENING AND HAS NOW
ENDED ACROSS MOST OF THE ADVISORY AREA. THERE MAY BE A LINGERING
PATCH OR TWO OF FREEZING DRIZZLE BUT THOSE TOO ARE EXPECTED TO
END VERY SHORTLY. RADARS AT MKX...DVN AND ARX HAVE ALL SHOWN A W
TO E CLEARING OF THE WEAK ECHOES WHILE AN AREA OF WEAK ECHOES
ASSOCIATED WITH SOME DRIZZLE AND LIGHT RAIN HAD BLOSSOMED
OVERHEAD BUT IS STEADILY MOVING TO THE E SO THIS PRECIP IS
EXPECTED TO END 9PM CST AS THE TAIL END OF THE LATEST MINOR SHORT
WAVE TROUGH MOVES E OF THE AREA. FORTUNATELY WHERE THIS PRECIP IS
OCCURRING SURFACE TEMPERATURES ARE ABOVE FREEZING.
THE LAKE AND PORTER INDIANA COUNTIES PORTION OF THE DENSE FOG
ADVISORY ALSO WAS ALLOWED TO EXPIRE AS THE FRONTAL BOUNDARY HAD
DRIFTED SLIGHTLY SOUTHWARD ALLOWING WINDS TO BECOME LIGHT
NORTHWEST AND VISIBILITIES TO IMPROVER ABOVE DENSE FOG CRITERIA.
THE REMAINDER OF THE DENSE FOG ADVISORY HAS BEEN EXTENDED UNTIL
9 PM CST. THE WEAK SURFACE REFLECTION OF THE SHORT WAVE WAS IN THE
VPZ-SBN AREA. AS IT CONTINUES SLOWLY TO THE E THE REST OF THE
EVENING THE FRONTAL BOUNDARY WILL CONTINUE TO SAG DEEPER INTO THE
AREA THAT REMAINS UNDER THE ADVISORY WITH AN THINNING OF THE DENSE
FOG EXPECTED TO OCCUR.
TRS
&&
.PREV DISCUSSION...
337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW...
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
DISCUSSION ON WINTER STORM.
WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND
CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES.
THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR
THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A
NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND
MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY
NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS
NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER
AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS.
THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH
TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY
NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS
FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY
SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION
ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL
LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH
SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT
TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR
ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL
LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING
AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE
COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS
OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET
IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER
NORTHWEST TRACK...I CHOOSE TO HOLD OFF.
THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET
ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING
AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN
RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS
MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING
SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF
SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF
I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE
CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY
RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING
THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE
EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE
AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN
AN SPS.
IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY
SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH.
STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY
PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND
WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE
EXPECTED.
THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR
TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW
ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS
THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY
LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS.
TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET
CLOSE TO CHICAGO AND INTERSTATE 80.
MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT
PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL
DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS
IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER
REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA.
KJB
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* NORTHEAST WIND 020-030 DEG BECOMING NORTH-NORTHWEST 340-350 DEG
AROUND MID EVENING.
* IFR CIG/VIS CONDITIONS THIS EVE WITH SOME PATCHY DRIZZLE. MAY
IMPROVE TO LOW-END MVFR CIG LATE TONIGHT/EARLY SATURDAY MORNING
BEFORE LOWERING TO IFR AGAIN DURING THE DAY.
* TIMING/TYPE OF ONSET OF PRECIP SATURDAY.
RATZER
//DISCUSSION...UPDATED 00Z...
SURFACE LOW PRESSURE WAS LIFTING NORTHEAST ACROSS NORTHERN INDIANA
AT 23Z...ALONG FRONT WHICH HAD BECOME STATIONARY JUST TO THE SOUTH
OF THE TERMINALS. THE LOW WILL CONTINUE TO TRACK OFF TO THE EAST
TONIGHT...ALLOWING LOW LEVEL WINDS TO GRADUALLY BACK FROM
NORTHEAST TO NORTHWEST BEYOND MID-EVENING. EXTENSIVE AREA OF
IFR CEILINGS AND 2-5SM VISIBILITY FOG WAS OCCURRING IN VERY MOIST
LOW LEVEL ENVIRONMENT IN THE VICINITY OF THE LOW AND STALLED
FRONT. SOME IMPROVEMENT MAY OCCUR LATE TONIGHT WITH LOW LEVEL
NORTHWEST WINDS EVENTUALLY DRAWING COOLER/DRIER AIR IN FROM
AREAS NORTH/NORTHWEST OF THE TERMINALS...THOUGH CEILINGS REMAIN
BELOW 1000 FT AGL ACROSS MUCH OF SOUTHERN WI AND WITH RELATIVELY
LIGHT WINDS OVERNIGHT EXPECT IFR CONDITIONS TO LINGER FOR SOME
TIME. PATCHY LIFR CONDITIONS WITH LINGERING PATCHY DRIZZLE AND
FREEZING DRIZZLE SHOULD IMPROVE LATER THIS EVENING HOWEVER AS
FRONTAL ZONE DRIFTS TO THE SOUTHEAST.
ATTENTION THEN TURNS TO STORM SYSTEM LIFTING OUT OF THE SOUTHERN
PLAINS AND AFFECTING THE LOCAL AREA SATURDAY AFTERNOON THROUGH
SUNDAY. WINDS ARE EXPECTED TO SHIFT BACK TO THE NORTHEAST BY MID-
MORNING SATURDAY AND INCREASE INTO THE 10-15 KT RANGE LATER IN THE
DAY AS SURFACE LOW PRESSURE MOVES OUT OF TEXAS AND TOWARD THE
BOOTHEEL OF MISSOURI BY EVENING. PRECIPITATION IS EXPECTED TO
DEVELOP NORTHWARD INTO THE CHICAGO TERMINAL AREA BY MID-
AFTERNOON...WITH FORECAST THERMAL PROFILES INDICATING
PRECIPITATION WILL BE A MIX OF SNOW...SLEET AND RAIN OR FREEZING
RAIN. SURFACE TEMPERATURES ARE EXPECTED TO BE RIGHT AROUND THE
FREEZING MARK...POSSIBLY JUST ABOVE FREEZING. THERE COULD BE A
PERIOD OF FREEZING DRIZZLE OR DRIZZLE BY MID-LATE MORNING AS LIFT
BEGINS TO DEVELOP AHEAD OF THE SYSTEM ATOP MOIST LOW LEVELS.
CEILINGS THEN EXPECTED TO DROP BACK SOLIDLY INTO IFR WITH ONSET OF
PRECIP.
MIXED SLEET/RAIN/FREEZING EXPECTED TO CONTINUE SATURDAY EVENING...
EVENTUALLY CHANGING TO ALL SNOW BEYOND THE END OF THE TAF PERIOD
SOMETIME EARLY SUNDAY MORNING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN IFR CONDITIONS THROUGH THIS EVENING WITH
GENERALLY MVFR VIS IN FOG PATCHY DRIZZLE.
* LOW CONFIDENCE IN CEILING TRENDS OVERNIGHT/EARLY SATURDAY.
* MEDIUM CONFIDENCE IN PRECIP ONSET TIME AND PRECIP TYPE SATURDAY
AFTERNOON.
* MEDIUM CONFIDENCE IN CEILINGS DETERIORATING INTO IFR BY LATE
SATURDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...SNOW ESPECIALLY IN THE MORNING. IFR LIKELY. BRIEF LIFR
POSSIBLE EARLY.
MONDAY...CHANCE OF SNOW SHOWERS. MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...CHANCE OF LIGHT SNOW. MVFR/IFR POSSIBLE.
THURSDAY...SLIGHT CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
RATZER
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 9 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM
SUNDAY.
IN...DENSE FOG ADVISORY...INZ010-INZ011-INZ019 UNTIL 9 PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 PM FRIDAY.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
609 PM CST FRI DEC 20 2013
.DISCUSSION...
337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW...
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
DISCUSSION ON WINTER STORM.
WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND
CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES.
THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR
THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A
NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND
MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY
NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS
NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER
AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS.
THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH
TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY
NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS
FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY
SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION
ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL
LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH
SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT
TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR
ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL
LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING
AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE
COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS
OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET
IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER
NORTHWEST TRACK...I CHOOSE TO HOLD OFF.
THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET
ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING
AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN
RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS
MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING
SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF
SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF
I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE
CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY
RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING
THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE
EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE
AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN
AN SPS.
IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY
SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH.
STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY
PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND
WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE
EXPECTED.
THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR
TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW
ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS
THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY
LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS.
TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET
CLOSE TO CHICAGO AND INTERSTATE 80.
MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT
PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL
DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS
IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER
REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA.
KJB
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* NORTHEAST WIND 020-030 DEG BECOMING NORTH-NORTHWEST 340-350 DEG
AROUND MID EVENING.
* IFR CIG/VIS CONDITIONS THIS EVE WITH SOME PATCHY DRIZZLE. MAY
IMPROVE TO LOW-END MVFR CIG LATE TONIGHT/EARLY SATURDAY MORNING
BEFORE LOWERING TO IFR AGAIN DURING THE DAY.
* TIMING/TYPE OF ONSET OF PRECIP SATURDAY.
RATZER
//DISCUSSION...UPDATED 00Z...
SURFACE LOW PRESSURE WAS LIFTING NORTHEAST ACROSS NORTHERN INDIANA
AT 23Z...ALONG FRONT WHICH HAD BECOME STATIONARY JUST TO THE SOUTH
OF THE TERMINALS. THE LOW WILL CONTINUE TO TRACK OFF TO THE EAST
TONIGHT...ALLOWING LOW LEVEL WINDS TO GRADUALLY BACK FROM
NORTHEAST TO NORTHWEST BEYOND MID-EVENING. EXTENSIVE AREA OF
IFR CEILINGS AND 2-5SM VISIBILITY FOG WAS OCCURRING IN VERY MOIST
LOW LEVEL ENVIRONMENT IN THE VICINITY OF THE LOW AND STALLED
FRONT. SOME IMPROVEMENT MAY OCCUR LATE TONIGHT WITH LOW LEVEL
NORTHWEST WINDS EVENTUALLY DRAWING COOLER/DRIER AIR IN FROM
AREAS NORTH/NORTHWEST OF THE TERMINALS...THOUGH CEILINGS REMAIN
BELOW 1000 FT AGL ACROSS MUCH OF SOUTHERN WI AND WITH RELATIVELY
LIGHT WINDS OVERNIGHT EXPECT IFR CONDITIONS TO LINGER FOR SOME
TIME. PATCHY LIFR CONDITIONS WITH LINGERING PATCHY DRIZZLE AND
FREEZING DRIZZLE SHOULD IMPROVE LATER THIS EVENING HOWEVER AS
FRONTAL ZONE DRIFTS TO THE SOUTHEAST.
ATTENTION THEN TURNS TO STORM SYSTEM LIFTING OUT OF THE SOUTHERN
PLAINS AND AFFECTING THE LOCAL AREA SATURDAY AFTERNOON THROUGH
SUNDAY. WINDS ARE EXPECTED TO SHIFT BACK TO THE NORTHEAST BY MID-
MORNING SATURDAY AND INCREASE INTO THE 10-15 KT RANGE LATER IN THE
DAY AS SURFACE LOW PRESSURE MOVES OUT OF TEXAS AND TOWARD THE
BOOTHEEL OF MISSOURI BY EVENING. PRECIPITATION IS EXPECTED TO
DEVELOP NORTHWARD INTO THE CHICAGO TERMINAL AREA BY MID-
AFTERNOON...WITH FORECAST THERMAL PROFILES INDICATING
PRECIPITATION WILL BE A MIX OF SNOW...SLEET AND RAIN OR FREEZING
RAIN. SURFACE TEMPERATURES ARE EXPECTED TO BE RIGHT AROUND THE
FREEZING MARK...POSSIBLY JUST ABOVE FREEZING. THERE COULD BE A
PERIOD OF FREEZING DRIZZLE OR DRIZZLE BY MID-LATE MORNING AS LIFT
BEGINS TO DEVELOP AHEAD OF THE SYSTEM ATOP MOIST LOW LEVELS.
CEILINGS THEN EXPECTED TO DROP BACK SOLIDLY INTO IFR WITH ONSET OF
PRECIP.
MIXED SLEET/RAIN/FREEZING EXPECTED TO CONTINUE SATURDAY EVENING...
EVENTUALLY CHANGING TO ALL SNOW BEYOND THE END OF THE TAF PERIOD
SOMETIME EARLY SUNDAY MORNING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN IFR CONDITIONS THROUGH THIS EVENING WITH
GENERALLY MVFR VIS IN FOG PATCHY DRIZZLE.
* LOW CONFIDENCE IN CEILING TRENDS OVERNIGHT/EARLY SATURDAY.
* MEDIUM CONFIDENCE IN PRECIP ONSET TIME AND PRECIP TYPE SATURDAY
AFTERNOON.
* MEDIUM CONFIDENCE IN CEILINGS DETERIORATING INTO IFR BY LATE
SATURDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...SNOW ESPECIALLY IN THE MORNING. IFR LIKELY. BRIEF LIFR
POSSIBLE EARLY.
MONDAY...CHANCE OF SNOW SHOWERS. MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...CHANCE OF LIGHT SNOW. MVFR/IFR POSSIBLE.
THURSDAY...SLIGHT CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
RATZER
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...6 PM SATURDAY TO 6 PM SUNDAY.
WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM
SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 PM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
317 PM CST THU DEC 19 2013
.DISCUSSION...
UPDATED...316 PM CST
DISCUSSION FOR WEEKEND SYSTEM WILL BE ISSUED SHORTLY...
KEY POINTS: A WINTER STORM WATCH WILL BE ISSUED FOR
LAKE...MCHENRY...WINNEBAGO...LEE...DEKALB AND KANE COUNTIES. IT WILL
BE IN EFFECT FROM SATURDAY EVENING THROUGH SUNDAY EVENING.
A FLOOD WATCH WILL BE IN EFFECT FROM MID SATURDAY MORNING THROUGH
EARLY SUNDAY MORNING FOR FORD...IROQUOIS...NEWTON...JASPER AND
BENTON COUNTIES.
TONIGHT THROUGH FRIDAY NIGHT
UPDATED...1224 PM CST
FRONTAL BOUNDARY IS DRAPED FROM THE CHICAGO METRO AREA WSW TO NEAR
THE QUAD CITIES THIS AFTERNOON. ASCENT IS FORECAST TO INCREASE THIS
EVENING AND TONIGHT ON TOP OF THE BOUNDARY WHICH WILL MEANDER SOME
AS THE SURFACE WAVE LIFTS ACROSS THE REGION. WARM ADVECTION ALOFT
LEAVES LITTLE DOUBT THAT PRECIP WILL MELT ALOFT WITH 3-4C SATURATED
WARM LAYER TEMPS AS FAR NORTH AS THE WI STATE LINE. THE BIG CONCERN
WILL BE SURFACE/GROUND TEMPERATURE TRENDS. TEMPERATURES ARE
EXPECTED TO MOSTLY HOLD STEADY INTO THE LATE EVENING...THEN COLDER
//BELOW FREEZING// SURFACE TEMPS WILL START TO TRICKLE SOUTHEAST
INTO FAR NORTHERN IL AS THE LOW STARTS TO PASS TO OUR SOUTH.
CURRENTLY IT APPEARS THAT ONLY THE FAR REACHES OF THE CWA...
INCLUDING PORTIONS OF OGLE...WINNEBAGO...BOONE...AND MCHENRY
COUNTIES...WILL SEE SURFACE TEMPERATURES FALLING BELOW FREEZING
OVERNIGHT AND WHERE THE CONCERN FOR LIGHT FREEZING RAIN AND LIGHT
ICE ACCUMULATIONS WILL BE. A FREEZING RAIN ADVISORY HAS BEEN ISSUED
FOR THESE COUNTIES...AND EXPECT A GLAZE UP TO A TENTH OF AN INCH OF
ICE FOR THESE AREAS.
BY MID MORNING FRIDAY...TEMPERATURES ARE EXPECTED TO CONTINUE TO
SLOWLY FALL WITH THE LOW DEPARTING EAST. FORCING QUICKLY TAPERS BUT
PERSISTENT LOW LEVEL MOISTURE AND WEAK OMEGA RAISES THE CONCERN FOR
FREEZING DRIZZLE TO SPREAD SOUTH OF THE CURRENT ADVISORY
AREA...PERHAPS AS FAR SOUTH AS THE I-80 CORRIDOR. MID/HIGH LEVEL
MOISTURE WILL BE PRESENT...HOWEVER MID LEVEL DRY LAYER IS EXPECTED
TO INHIBIT SEEDER/FEEDER FROM INTRODUCING ICE INTO THE LOW LEVEL
MOISTURE LAYER...WHICH ONLY HAS TEMPERATURES AS COOL AS -5C.
SURFACE TEMPERATURES WILL BE RIGHT AROUND THE FREEZING MARK. FOR
NOW PLAN ON HIGHLIGHTING AREA WITH AN SPS...AND CANNOT RULE OUT
EXPANSION OF ADVISORY FARTHER SOUTH LATER INTO THE DAY FRIDAY IF
IT APPEARS TEMPERATURES WILL BE COOLER OR IF PRECIP MORE ROBUST.
DEUBELBEISS
DISCUSSION FOR WEEKEND SYSTEM WILL BE ISSUED SHORTLY...
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
UPDATED 316 PM CST
SUNDAY NIGHT...
GUIDANCE CONTINUES TO BE CONSISTENT IN DELIVERING A SHOT OF ARCTIC
AIR IN THE WAKE OF THE SIGNIFICANT WEEKEND STORM. A NORTHERN STREAM
TROUGH CURRENTLY NEAR THE NORTH POLE WILL DIG IN OVER THE NORTH
CENTRAL CONUS COUPLED WITH A ~1040 MB HIGH DROPPING SOUTH FROM THE
NORTHERN PLAINS. ALL OF THE SYSTEM SNOWS SHOULD BE OFF TO THE EAST
SUNDAY NIGHT...BUT POSITIVE VORTICITY ADVECTION FROM SHORT WAVES
ROTATING AROUND DEEP UPPER TROUGH COULD SQUEEZE OUT SOME LIGHT SNOW
OR FLURRIES IN THE ARCTIC AIR MASS. THE ECMWF CONTINUES TO BE MOST
BULLISH IN SQUEEZING OUT LIGHT QPF OVER THE AREA. THERE ALSO COULD
BE A BRIEF PERIOD OF FAVORABLE LAKE EFFECT CONDITIONS FOR PORTIONS
OF NW INDIANA DEPENDING ON IF WINDS CAN REMAIN CLOSER TO DUE NORTH
BEFORE BACKING WEST NORTHWEST. TEMPERATURES WILL PLUMMET IN STRONG
COLD ADVECTION BUT PERSISTENT NW WINDS AND CLOUD COVER COULD LIMIT
HOW FAR THEY FALL. WITH THE RAPIDLY FALLING TEMPERATURES SUNDAY
NIGHT...THERE COULD VERY WELL BE A FLASH FREEZE OF ANY REMAINING
MOISTURE ON THE GROUND.
MONDAY...
MAINTAINED A SLIGHT CHANCE OF FLURRIES ON MONDAY MORNING AS THE DEEP
UPPER TROUGH WILL BE OVERHEAD AND IT MAY NOT BE HARD TO SQUEEZE OUT
DENDRITES DESPITE THE COLD DRY AIRMASS. ALSO GUIDANCE INDICATES A
FAIRLY STOUT WAVE FOCUSED INTO THE NORTHEAST CWA AND WISCONSIN...SO
FELT COMFORTABLE WITH THE SLIGHT CHANCE POP FROM GUIDANCE BLEND
INITIALIZATION FOR NORTHEAST IL AND EXTREME NW INDIANA. HIGH
TEMPERATURES MONDAY AND LOWS MONDAY NIGHT WILL BE COLD
EVERYWHERE...BUT HOW COLD WILL DEPEND ON WHICH AREAS MAINTAIN
SUBSTANTIAL SNOWPACK AFTER THE WEEKEND SYSTEM. AT THIS TIME...IT
APPEARS THAT THE NORTHERN CWA WOULD HAVE THE BEST CHANCE. WITH
SURFACE HIGH BEING NEAR OR OVER THE AREA AND NO MORE THAN PARTLY
CLOUDY SKIES EXPECTED...DROPPED LOW TEMPERATURES MONDAY NIGHT FROM
PREVIOUS FORECAST TO 5 TO 10 BELOW WEST OF THE FOX VALLEY. STAYED
MORE CONSERVATIVE IN THE SOUTHERN CWA WHERE LITTLE OR NO SNOW COVER
SHOULD BE LEFT. TO NOTE...THE ECMWF AND GFS WHICH HAVE CLEAR SKIES
HAVE LOWS IN THE COLDEST SPOTS 10 DEGREES COLDER THAN IN FORECAST
GRIDS...WHILE CANADIAN MODEL KEEPS CLOUD COVER AND IS A GOOD DEAL
WARMER.
TUESDAY NIGHT THROUGH THURSDAY...
AFTER A BITTERLY COLD START TO CHRISTMAS EVE DAY...SOUTHWEST WARM
ADVECTION BEHIND TROUGH DEPARTING TO THE EAST WILL ENABLE A DECENT
AFTERNOON TEMPERATURE RECOVERY...BUT STILL WELL BELOW CLIMO. COULD
SEE TEMPERATURES BEING A BIT WARMER THAN CURRENTLY FORECAST IN AREAS
WITHOUT SNOWCOVER. WILL HAVE TO WATCH FOR A NORTHERN STREAM WAVE
BEING A BIT FARTHER SOUTH THAN MODEL CONSENSUS ON CHRISTMAS EVE
NIGHT...BUT WITH ECMWF TRENDING SOUTH...INDICATED A SLIGHT CHANCE OF
LIGHT SNOW NEAR THE WISCONSIN BORDER. THIS FEATURE COULD THEN GO ON
TO RESULT IN AT LEAST SOME LIGHT SNOW OR FLURRIES IN THE AIR FOR THE
ENTIRE AREA ON CHRISTMAS DAY. THIS WOULD BE A CONSOLATION PRIZE FOR
AREAS THAT LOSE THEIR SNOW COVER THIS WEEKEND...BUT FOR AREAS THAT
KEEP AT LEAST 1 INCH OF SNOW ON THE GROUND...A WHITE CHRISTMAS IS
HIGHLY LIKELY. TEMPERATURES WILL MODERATE TO NEAR NORMAL ON
CHRISTMAS DAY...WITH ANOTHER SHOT OF ARCTIC AIR POSSIBLE ON THURSDAY
BEHIND THE CHRISTMAS DAY SYSTEM.
CONFIDENCE IN A WHITE CHRISTMAS FOR AREAS THAT MAINTAIN AT LEAST 1
INCH OF SNOW COVER THIS WEEKEND...HIGH.
RC
&&
.HYDROLOGY...
THERE CONTINUES TO BE AN ELEVATED THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWERING CIGS AND VSBYS THIS AFTERNOON WITH DRIZZLE LATE.
* IFR CONDITIONS OVERNIGHT WITH CONTINUED DRIZZLE OR RAIN.
* POSSIBLE FREEZING RAIN TOMORROW.
LENNING
//DISCUSSION...UPDATED 18Z...
LOTS OF CONCERNS OVER THE NEXT TWO OR THREE DAYS. A FRONTAL ZONE
PARKED OVER THE AREA WILL REMAIN IN THE NEIGHBORHOOD INTO TOMORROW
MORNING. THIS BOUNDARY WILL PROVIDE THE FOCUS FOR LOWERING CIGS
AND VSBYS THIS AFTERNOON ESPECIALLY AS MOISTURE INCREASES ALOFT.
LATEST TAFS DELAY THE ONSET OF DRIZZLE INTO THIS EVENING BASED ON
LACK OF ANY CURRENT OBSERVATIONS...BUT THIS SHOULD NOT BE THE MAJOR
IMPACT REGARDLESS. WINDS NORTH OF THE FRONT ARE NORTHEAST WHILE
WINDS SOUTH ARE GENERALLY MORE SOUTH OR SOUTHWEST.
SFC TEMPERATURES FALL NORTH OF THE BOUNDARY TODAY AND REMAIN VERY
CLOSE TO FREEZING FOR AN EXTENDED PERIOD TOMORROW. ELECTED TO GO
WITH THE MORE OPTIMISTIC OUTCOME FOR NOW WHICH KEEPS ORD/MDW PRECIP
AS LIQUID ALL DAY FRIDAY...BUT FREEZING RAIN IS A DEFINITE
POSSIBILITY AT ORD/MDW AND A LIKELIHOOD AT RFD. A SATURATED DEEP
WARM LAYER ALOFT WOULD NARROW THE OPTIONS TO RAIN OR FREEZING
RAIN...WITH NEITHER SLEET NOR SNOW APPEARING LIKELY THROUGH AT
LEAST MID DAY FRIDAY BASED ON EXISTING GUIDANCE. FRIDAY AFTERNOON
TOWARD RFD THE WARM LAYER COOLS ALOFT AND THE COLD SURFACE LAYER
DEEPENS...INTRODUCING THE POSSIBILITY OF SLEET IN THAT AREA BUT
STILL NOT TOWARD ORD/MDW.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN TIMING AND MAGNITUDE OF LOWER CONDITIONS
THIS AFTERNOON.
* HIGH CONFIDENCE IN RAIN STARTING BY THIS EVENING AND CONTINUING
OVERNIGHT.
* HIGH CONFIDENCE IN LOWERING CIG/VSBY TRENDS TONIGHT AND
TOMORROW.
* MEDIUM CONFIDENCE THAT PRECIP REMAINS MOSTLY LIQUID THROUGH
TOMORROW MORNING AT ORD/MDW.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC RAIN OR SNOW. MVFR TO IFR CIGS.
SATURDAY...A WINTRY MIX OF PRECIP IS EXPECTED DURING THE DAY WITH
RAIN OR FREEZING RAIN OVERNIGHT. MVFR TO IFR CIGS.
SUNDAY...SNOW. MVFR TO IFR CIGS.
MONDAY...FLURRIES IN THE MORNING. VFR.
TUESDAY...VFR.
WEDNESDAY...SCHC OF SNOW DURING THE DAY. MVFR IMPROVING TO VFR.
JEE
&&
.MARINE...
308 PM CST
THERE ARE TWO LOWS SET TO MOVE FROM THE SOUTHERN PLAINS TO THE
LOWER/EASTERN GREAT LAKES REGION THROUGH SUNDAY. THE SECOND ONE WILL
HAVE A LARGER INFLUENCE ON THE WINDS ACROSS THE LAKE...NAMELY
SATURDAY NIGHT THROUGH EARLY MONDAY. AS WINDS TURN
NORTHERLY BEHIND THIS LOW...SPEEDS WILL INCREASE BUT ARE LIKELY TO
REMAIN BELOW GALES ON SUNDAY...ALTHOUGH COULD BE CLOSE ESPECIALLY
IF THE SYSTEM IS DEEPER THAN FORECAST.
IN THE IMMEDIATE NEAR TERM...A FRONT WILL REMAIN DRAPED ACROSS THE
SOUTHERN TWO TO FOUR OPEN WATER ZONES OF LAKE MICHIGAN...WHERE
WINDS WILL BE SOMEWHAT VARIABLE IN SPEED. THIS FRONT WILL INCH
SOUTHWARD FRIDAY MORNING IN THE WAKE OF THE FIRST LOW.
A WINTRY MIX IS EXPECTED ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE WITH BOTH SYSTEMS...TONIGHT AND FRIDAY AND AGAIN SATURDAY
NIGHT WHICH SHOULD CHANGE TO ALL SNOW SUNDAY.
IN THE WAKE OF THESE SYSTEMS...STRONG HIGH PRESSURE WILL PASS TO
THE SOUTH OF THE REGION BEFORE LIKELY STRONG SOUTHERLY WINDS TAKE
EFFECT ACROSS THE ENTIRE LAKE SOMETIME CHRISTMAS EVE NIGHT INTO
CHRISTMAS.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008...MIDNIGHT
FRIDAY TO NOON FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740...9 AM FRIDAY TO 9 PM FRIDAY.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
314 PM CST Thu Dec 19 2013
.DISCUSSION...
ISSUED 253 PM CST Thu Dec 19 2013
Main focus today is on the weekend storm.
SHORT TERM...Tonight through Saturday night.
Morning upper air data displays the digging upper low system in
the southwest US and the upper flow over the plains shifting to
more a east-west flow ahead of the western system. This has
allowed plenty of low level southerly flow over the plains into
the MO/IL region, strengthening the stationary frontal zones over
KS to northern MO to northern IL.
As the wetern system slowly rounds the bottom of the trof, another
upper trof over the northwest plains provides enough pus to get
the arctic cold air to slowly move into IL late tonight and
crossing the rest of IL during the day Friday. Some minor
precipitation in the overrunning of the front late tonight and
through midday Friday, with rain the pcpn type through Friday.
Only on Friday night will there be enough cooling for a mixture of
freezing rain Friday night over the northern half.
On early Saturday morning, the main pcpn begins to develop as the
west coast upper low develops a surface low center that moves up
the now stalled front over the OH Valley. The pcpn moves up into
the southern parts of the CWA Saturday and spreads north through
the day, with a mixture of freezing rain and rain in some areas as
the warm air slowly moves north. Pcpn amounts in the rain are
significant with good lift over the front. Major QPF forecast over
the southeast 1/3, so will continue the flood watch and have added
chc of thunder due to instability seen in the forecast soundings
above the surface boundary level cold air dome. added the possible
thunder Saturday afternoon and evening when best lift is seen.
12z models are a little more to the east than previous runs on the
prog of the surface low, over southern Il to northeast IN this
run. Will have to watch this new trend and see if that affects the
location of the cold air.
Position of the deformation zone and the surface low shows best
snow area in the region along and west of the Illinois River.
Storm total much the same at 3-5.5 inch amounts in this area.
LONG TERM...Sunday through Thursday.
Cold conditions the rule after this system moves through. A
secondary cold frontal system does move through on Wednesday to
Thursday, and so kept the chance of snow with no accumulation.
Goetsch
&&
.AVIATION...
ISSUED 1159 AM CST Thu Dec 19 2013
VFR conditions early this afternoon will deteroriate during
mid/late afternoon and into tonight as low clouds and fog are
expected to develop with ceilings dropping to below 1K ft and
vsbys getting down to 1-3 miles and latest HRRR model ceiling/vsby
parameters support. Also have light rain showers developing later
this afternoon and tonight and continues into Friday morning. A
frontal boundary over nw parts of IL/MO, currently between GBG and
MLI to slowly press se toward the IL river later tonight and
Friday morning. South winds 8-13 kts this afternoon to turn se
this evening and then wsw during Fri morning, except north at PIA
where front passes through. Continue LLWS from I-55 se tonight
into mid morning Friday with 2k ft sw winds of 45-50 kts and
strongest at se TAF sites of CMI & DEC where LLWS could linger
most of Friday morning.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH from late Friday night through late Saturday night
FOR ILZ044>046-052>057-061>063-066>068-071>073.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1201 PM CST THU DEC 19 2013
.DISCUSSION...
328 AM CST
TODAY THROUGH TONIGHT...
OVER THE NEXT SEVERAL DAYS WILL FEATURE A METEOROLOGICAL ROLLER
COASTER...WITH A WIDE RANGE OF TEMPERATURES ABOVE/BELOW
FREEZING...PRECIPITATION CHANGING FROM FROZEN TO LIQUID AND BACK TO
FROZEN...MELTING SNOWPACK WITH POTENTIAL FOR ABUNDANT RAINFALL ON
FROZEN GROUND AND CONSIDERABLE ICE ON AREA STREAMS LEADING TO
POSSIBLY HYDRO CONCERNS. TO FURTHER COMPOUND THE HYDRO CONCERNS WILL
BE THAT IF ICE BREAKS UP ON STREAMS IT MAY EASILY BECOME LOCKED BACK
UP AS SUB-FREEZING AIR RETURNS FOR EARLY NEXT WEEK.
MAIN ITEM ON THE AGENDA FOR TODAY...CAN FOG DEVELOP AND HOW WARM
WILL SFC TEMPS BECOME THIS AFTN. A WEAK SFC LOW NORTHEAST OF THE
STRAITS OF MACKINAW CONTINUES TO PUSH EAST WITH A TRAILING FRONTAL
BOUNDARY STRETCHING WEST THROUGH CENTRAL WISC INTO CENTRAL IOWA.
BROAD ANTI-CYCLONIC FLOW OVER THE CANADIAN PRAIRIES IS SEEPING
SOUTH...AND EXPECTED TO SHARPEN THE BAROCLINIC ZONE ALONG THE
STALLED FRONTAL BOUNDARY.
MAIN CONCERNS FOR TODAY WILL REVOLVE AROUND WHEN/IF FOG CAN
DEVELOP...ALONG WITH STEADILY MOISTENING OF THE NEAR SFC ENVIRONMENT
AS ADDTL MOISTURE ADVECTS NORTH FROM A NEARLY +3 SIGMA V-WIND
COMPONENT INTO AN ABNORMALLY HIGH PWAT REGION OF NORTHERN
IL/NORTHWEST IN. SOUNDINGS HAVE STEADILY OVERDONE MOISTURE...AND
PRESENT T/TD DEPRESSIONS IN PLACES REMAIN IN EXCESS OF 5 DEG TO AS
MUCH AS 10 DEG...WHICH PLACES LESS CONFIDENCE ON THE DEVELOPMENT OF
FOG FOR A FEW HOURS. THERE ARE A FEW LOCATIONS THAT HAVE SOME PATCHY
FOG THIS MORNING...HOWEVER THE COVERAGE IS LIKELY GOING TO REMAIN
LOW. THERMAL BOUNDARY EXISTS FROM MOLINE EAST THROUGH
GARY/VALPO...TO THE NORTH TEMPS ARE IN THE TEENS/20S AND SOUTH THEY
ARE IN THE MID/UPR 30S.
GUIDANCE HAS CONSOLIDATED AROUND LATE MORNING WITH THE BEGINNING
TIMEFRAME FOR DRIZZLE/LGT RA...SO HAVE PUSHED BACK TIMING UNTIL
THEN. TEMPS NORTH OF I-88 WILL LIKELY REMAIN IN THE MID 30S TDY
WHILE SOUTH OF THIS LINE TEMPS SHUD WARM TO ARND 40.
THEN FOR TONIGHT IT APPEARS THE SETUP CONTINUES TO FAVOR FREEZING
RAIN...MAINLY FOR AREAS ALONG AND WEST OF LASALLE TO WAUKEGAN. WEAK
LOW WILL LIFT NORTHEAST ALONG THE BAROCLINIC ZONE WITH THE DEEPER
MOISTURE PEELING OFF TO THE NORTHEAST...WHICH WILL LEAVE IN ITS WAKE
A BAGGY ENVIRONMENT. WITH THE LACK OF LIFT...AND TEMPS HOVERING ARND
FREEZING TO JUST BELOW FREEZING...AND THERMAL PROFILES SHOWING A
CONSIDERABLE WARM LAYER...ANY PRECIP WILL LIKELY BE LGT AND FREEZING
RAIN OR FREEZING DRIZZLE. EAST OF THE AFOREMENTIONED LINE SFC TEMPS
SHUD HOLD RIGHT AT FREEZING OR JUST ABOVE...KEEPING PRECIP IN LIQUID
FORM. NONETHELESS WITH THE GROUND STILL FROZEN FROM THE PAST FEW
WEEKS...UNTREATED SURFACES MAY STILL HAVE SOME SLICK SPOTS.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN FZRA TONIGHT WEST OF LASALLE TO WAUKEGAN...HIGH.
CONFIDENCE IN AREAS EAST OF THIS LINE SEEING FZRA...MEDIUM.
FRIDAY THROUGH SUNDAY...
THE FORECAST AREA WILL CONTINUE TO BE IN A RATHER MOIST
ENVIRONMENT...WITH LINGERING LLVL/MID-LVL MOISTURE IN THE WAKE OF
THE DEPARTING SFC LOW...THUS FRI MORNING MAY CONTINUE TO SEE SPOTTY
FZRA/FZDZ OR LGT SN FOR THE FAR NW. FURTHER EAST TEMPS WILL LIKELY
REMAIN ABOVE FREEZING AND AGAIN ANY PRECIP WILL BE LGT AND RAIN.
SFC RIDGE ACROSS THE NORTHERN PLAINS/UPPER MIDWEST WILL SAG SOUTH
AND BECOME ORIENTED FROM THE CENTRAL PLAINS NORTHEAST TO WESTERN
LAKE SUPERIOR...PLACING THE CONTINUED BAROCLINIC ZONE SOMEWHERE
ACROSS THE CWFA AND BECOMING ORIENTED FROM SW TO NE PERHAPS FROM
LASALLE IL TO KENOSHA WI. TEMPS WILL REMAIN NEARLY STEADY THROUGHOUT
THE DAY IN THE LOW/MID 30S TO PSBLY ARND 40 ACROSS THE FAR SE CWFA.
FOCUS BEYOND FRI WILL BE ON THE HIGHLY ANTICIPATED MID-LVL VORT
MAX...PROGGED TO SLIDE EAST ACROSS THE SOUTHERN ROCKIES INTO WEST
TEXAS FRI NGT. DOWNSTREAM OF THIS FEATURE THE RIDGE WILL BECOME
PARKED ACROSS THE WESTERN ATLANTIC/SOUTHEAST COAST...ALLOWING A
CONSIDERABLE PLUME OF MOISTURE TO ADVECT NORTH THROUGH THE OZARKS
INTO THE TENN/OHIO VALLEY. GUIDANCE HAS BEEN CONSISTENT OVER THE
PAST FEW DAYS WITH AN ABUNDANCE OF PRECIP THROUGHOUT THIS
REGION...THE UNCERTAINTY IS ON HOW FAR NORTH IT WILL STRETCH.
CYCLOGENESIS CONTINUES TO BE PROGGED OVER CENTRAL TEXAS...AND
QUICKLY LIFT NORTH/NORTHEAST SAT TO FAR SOUTHERN IL BY EARLY SUN
MORNING. MODELS WILL LIKELY CONTINUE TO DEMONSTRATE CORRECTIONS OR A
WOBBLE ON THE PRECISE SFC LOW PATH...LARGELY IN PART FROM THE
PRESENT SNOW COVER/BARE GROUND LINE.
AS FOR P-TYPE SAT/SUN...THIS TOO CONTINUES TO EVOLVE WITH THE LATEST
FORECAST SOLUTIONS. THE EC/GFS HAVE SLIGHTLY DIFFERENT IDEAS ON THE
PATH OF THE SYSTEM...WHICH WILL DICTATE WHERE RAIN AND/OR SNOW WILL
FALL. NOT TO MENTION HOW MUCH OF EACH. AT THIS JUNCTURE HAVE OPTED
TO MAINTAIN THE CURRENT THINKING RATHER THAN FLIP-FLOPPING THE
FORECAST...GIVEN THE UNCERTAINTY THAT REMAINS. SOME COOLING DOES
APPEAR TO TAKE SHAPE FOR THE NORTH/NORTHWEST CWFA SAT...WHICH COULD
KEEP TEMPS SUB-FREEZING OR AT FREEZING THROUGHOUT THE DAY SAT.
850MB LOW IS PROGGED TO LIFT NORTHEAST ACROSS THE CWFA...CURRENTLY
SHAPING UP TO BE ALONG A PONTIAC TO CHICAGO LINE. THIS WOULD LIKELY
DISPLACE THE DEFORMATION ZONE TO THE NORTHWEST ACROSS THE FAR NW
CWFA SAT EVENING/EARLY SUN. THERE HAS ALSO BEEN CONSISTENCY IN A DRY
WEDGE LIFTING NE IN THE WAKE OF THE SFC LOW...WHICH COULD FEATURE A
PERIOD OF DRY WX SUN MORNING FOR THE FAR SE CWFA.
FRONTAL BOUNDARY SWEEPS EAST ACROSS THE FORECAST AREA BY MIDDAY
SUN...WITH FLOW BECOMING UNIFORM FROM THE NORTH/NORTHWEST. 500MB
TROUGH AXIS THEN PUSHES OVER THE REGION...WITH ANY LINGERING PRECIP
FALLING AS LGT SNOW SUN AFTN/EVE SETTING THE STAGE FOR LAKE EFFECT
DOWNSTREAM OF LAKE MICHIGAN.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN SNOW REMAINING NW OF LASALLE TO WAUKEGAN THRU SAT
NGT...MEDIUM/HIGH.
MONDAY THROUGH CHRISTMAS DAY...
ENSEMBLES HAVE REMAINED RATHER CONSISTENT WITH A SIMILAR SETUP OF
TWO RIDGES INFLUENCING THE WEATHER PATTERN. ONE BEING PARKED ACROSS
THE EASTERN PACIFIC...THE OTHER OVER THE WESTERN ATLANTIC. THIS
SETUP ALLOWS FOR THE CONTINUED TROUGHING ACROSS THE CENTER OF THE
COUNTY INCLUDING THE GREAT LAKES REGION. HOWEVER BY CHRISTMAS DAY
THESE FEATURES ARE PROGGED TO WEAKEN...WITH MID-LVL FLOW OVER THE
CENTRAL CONUS FLATTENING OUT.
THERE IS SOME INDICATIONS THAT BEYOND CHRISTMAS DAY A HIGH AMPLITUDE
RIDGE WILL BEGIN TO DEVELOP ACROSS FAR WESTERN CANADA...AND COULD
EVENTUALLY DEVELOP A DOWNSTREAM TROUGH YET AGAIN FOR THE GREAT LAKES
REGION LATER NEXT WEEK.
MON/TUE OPERATIONAL SOLUTIONS HAVE A BROAD SFC RIDGE MOVING EAST
ACROSS THE GREAT LAKES REGION AS THE MID-LVL TROUGH AXIS PIVOTS
EAST. THERMAL TROUGH ALOFT WILL LIKELY KEEP TEMPS IN THE TEENS/LOW
20S MON THEN BEGIN TO MODERATE INTO THE 20S BY TUE. WITH THE
AFOREMENTIONED DISCUSSION ON A FLATTENING FLOW...TEMPS MAY RETURN TO
SEASONAL CONDITIONS OR LOW 30S BY CHRISTMAS DAY. MODELS ARE
INDICATING A WEAK MOISTURE STARVED BOUNDARY ARRIVING ACROSS THE
REGION FOR CHRISTMAS DAY...COULD PROVIDE A FEW FLURRIES/LGT SNOW.
CONFIDENCE IN EXTENDED PERIODS...HIGH.
BEACHLER
&&
.HYDROLOGY...
THERE CONTINUES TO BE AN ELEVATED THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LOWERING CIGS AND VSBYS THIS AFTERNOON WITH DRIZZLE POSSIBLE.
* IFR CONDITIONS OVERNIGHT WITH CONTINUED DRIZZLE OR RAIN.
* POSSIBLE FREEZING RAIN TOMORROW.
LENNING
//DISCUSSION...UPDATED 18Z...
LOTS OF CONCERNS OVER THE NEXT TWO OR THREE DAYS. A FRONTAL ZONE
PARKED OVER THE AREA WILL REMAIN IN THE NEIGHBORHOOD INTO TOMORROW
MORNING. THIS BOUNDARY WILL PROVIDE THE FOCUS FOR LOWERING CIGS
AND VSBYS THIS AFTERNOON ESPECIALLY AS MOISTURE INCREASES ALOFT.
LATEST TAFS DELAY THE ONSET OF DRIZZLE INTO THIS EVENING BASED ON
LACK OF ANY CURRENT OBSERVATIONS...BUT THIS SHOULD NOT BE THE MAJOR
IMPACT REGARDLESS. WINDS NORTH OF THE FRONT ARE NORTHEAST WHILE
WINDS SOUTH ARE GENERALLY MORE SOUTH OR SOUTHWEST.
SFC TEMPERATURES FALL NORTH OF THE BOUNDARY TODAY AND REMAIN VERY
CLOSE TO FREEZING FOR AN EXTENDED PERIOD TOMORROW. ELECTED TO GO
WITH THE MORE OPTIMISTIC OUTCOME FOR NOW WHICH KEEPS ORD/MDW PRECIP
AS LIQUID ALL DAY FRIDAY...BUT FREEZING RAIN IS A DEFINITE
POSSIBILITY AT ORD/MDW AND A LIKELIHOOD AT RFD. A SATURATED DEEP
WARM LAYER ALOFT WOULD NARROW THE OPTIONS TO RAIN OR FREEZING
RAIN...WITH NEITHER SLEET NOR SNOW APPEARING LIKELY THROUGH AT
LEAST MID DAY FRIDAY BASED ON EXISTING GUIDANCE. FRIDAY AFTERNOON
TOWARD RFD THE WARM LAYER COOLS ALOFT AND THE COLD SURFACE LAYER
DEEPENS...INTRODUCING THE POSSIBILITY OF SLEET IN THAT AREA BUT
STILL NOT TOWARD ORD/MDW.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN TIMING AND MAGNITUDE OF LOWER CONDITIONS
THIS AFTERNOON.
* HIGH CONFIDENCE IN RAIN STARTING BY THIS EVENING AND CONTINUING OVERNIGHT.
* HIGH CONFIDENCE IN LOWERING CIG/VSBY TRENDS TONIGHT AND
TOMORROW.
* MEDIUM CONFIDENCE THAT PRECIP REMAINS MOSTLY LIQUID TOMORROW AT ORD/MDW.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC RAIN OR SNOW. MVFR TO IFR CIGS.
SATURDAY...A WINTRY MIX OF PRECIP IS EXPECTED DURING THE DAY WITH
RAIN OR FREEZING RAIN OVERNIGHT. MVFR TO IFR CIGS.
SUNDAY...SNOW. MVFR TO IFR CIGS.
MONDAY...FLURRIES IN THE MORNING. VFR.
TUESDAY...VFR.
WEDNESDAY...SCHC OF SNOW DURING THE DAY. MVFR IMPROVING TO VFR.
JEE
&&
.MARINE...
414 AM CST
LOW PRESSURE IS OVER THE NORTHERN LAKES THIS MORNING AND IT WILL
WEAKEN AS IT SHIFTS EAST. A COLD FRONT PUSHES DOWN THE LAKE TODAY
AND STALLS OVER SOUTHERN LAKE MICHIGAN THIS AFTERNOON AND
OVERNIGHT. WINDS TURN NORTH AND THEN EAST BEHIND THE FRONT AND
INCREASE TO 15 TO 25 KT...WITH SOUTH WINDS 10 TO 20 KT SOUTH OF THE
FRONT. WINDS FINALLY BECOME UNIFORMLY NORTH TO NORTHEAST FRIDAY
MORNING. AS SUCH THE 15 TO 25 KT WINDS MOVE ALONG THE NEARSHORE
WATERS NORTH OF CALUMET HARBOR EARLY FRIDAY MORNING. HAZARDOUS
WAVES ARE ALSO LIKELY FRIDAY AND POSSIBLY INTO FRIDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED...BUT DID NOT ISSUE ONE
AT THIS TIME. WINDS AND WAVES WILL BE JUST ON THE CUSP OF SMALL
CRAFT CRITERIA...SO DECIDED TO HOLD OFF JUST A LITTLE LONGER ON THE
NEXT SMALL CRAFT ADVISORY.
THE NEXT LOW PASSES SOUTH OF THE LAKE FRIDAY AND IT WEAKENS AS IT
CONTINUES OFF TO THE NORTHEAST. THE GRADIENT WEAKENS AS DO WINDS
WITH EAST WINDS EXPECTED FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE
PASSES TO THE NORTHWEST OF THE LAKE SATURDAY...THEN THE NEXT LOW
PUSHES UP THE OHIO RIVER VALLEY SATURDAY NIGHT INTO SUNDAY. WINDS
INCREASE AND BECOME NORTH SUNDAY THEN NORTHWEST SUNDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED SATURDAY NIGHT THROUGH
MONDAY FOR HIGH WINDS AND WAVES. OVER THE OPEN WATERS...WINDS TO 30
KT ARE EXPECTED. WINDS TURN WEST BEHIND THE LOW MONDAY NIGHT AND
CONTINUE TO WEAKEN AS HIGH PRESSURE MOVES OVER THE WESTERN LAKES
MONDAY NIGHT. INCREASING SOUTH WINDS ARE EXPECTED TUESDAY BETWEEN
THE DEPARTING LOW AND LOW PRESSURE SYSTEM OVER ONTARIO.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008...MIDNIGHT
FRIDAY TO NOON FRIDAY.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Lincoln IL
1159 AM CST Thu Dec 19 2013
.DISCUSSION...
ISSUED 1050 AM CST Thu Dec 19 2013
Will update the forecast to go with milder highs in the mid to
upper 40s today, with some lower 50s over sw counties where less
snow cover of 1 inch or less from Jacksonville sw and from I-70 se.
No fog or low clouds developing yet over central IL but HRRR does
develop some fog and especially low clouds over northern half of
CWA during the afternoon due to snow melt and increase snow melt
and winds lighter over the IL river valley. So will continue
patchy fog and slight chance of light rain showers during mid/late
afternoon from I-72 north this afternoon with low clouds also
expected to develop. A cold front over far nw IL into nw MO will
press slowly se toward Galesburg during the afternoon and evening
and this will help develop some light rain showers. Temps looks
warm enough through this evening for precipitation to stay all
rain even over Knox and Stark counties.
07
&&
.AVIATION...
ISSUED 1159 AM CST Thu Dec 19 2013
VFR conditions early this afternoon will deteroriate during
mid/late afternoon and into tonight as low clouds and fog are
expected to develop with ceilings dropping to below 1K ft and
vsbys getting down to 1-3 miles and latest HRRR model ceiling/vsby
parameters support. Also have light rain showers developing later
this afternoon and tonight and continues into Friday morning. A
frontal boundary over nw parts of IL/MO, currently between GBG and
MLI to slowly press se toward the IL river later tonight and
Friday morning. South winds 8-13 kts this afternoon to turn se
this evening and then wsw during Fri morning, except north at PIA
where front passes through. Continue LLWS from I-55 se tonight
into mid morning Friday with 2k ft sw winds of 45-50 kts and
strongest at se TAF sites of CMI & DEC where LLWS could linger
most of Friday morning.
07
&&
.PREV DISCUSSION...
ISSUED 311 AM CST Thu Dec 19 2013
High pressure sliding to the southeastern corner of the country as
a cold front slowly approaches the Midwest. A vigorous wave is
digging in over the southwest and translating into more
southwesterly flow over the region. Temperatures slowly increasing
as the airmass modifies with persistent moisture and warm air
advection. Cold front on the way to move through the area late
tonight and tomorrow morning...eventually stalling invof the Ohio
River Valley. Initial fropa less of an issue, with predominantly
rain for ILX. However, the front will provide a focus for precip
in the southeast...and a path to follow for the next wave ejecting
out of the southwest. Models have been very inconsistent with
track and thermodynamics...and are starting to waiver in the
strength overall. That being said, the trend to a more northerly
track is reflected in the forecast.
SHORT TERM...Today and Tonight...
Warmer as southerly winds usher in temps into the 40s. Overnight
expected to remain mostly above freezing as well. Pops return to
the forecast late this afternoon in the extreme NW as rain makes
its way into Central Illinois. Rain chances continue through the
overnight with the front as the winds slowly shift to
northwesterly behind the front and cooler air filters in. Cold air
not moving in very quickly however as the boundary is relatively
weak/the thermal gradient is less significant. For now, the
initial front is dominated by rain. Problems creep in after
midnight tomorrow night as temperatures finally drop and the
precip changes over to freezing rain for the northern half of the
state.
LONG TERM...Saturday through Wednesday...
Models still a problem, lacking continuity and consistency. Trend
to the north is pronounced enough to be reflected however. This
same trend broadens the developing warm sector and reduces the
coldest air. Ice/freezing rain confined mostly to NW of the
Illinois River Valley for Saturday morning, though a transition to
liquid will likely fall between the valley and the I-55 corridor.
Freezing rain in the NW and rain in the SE will continue through
the afternoon and evening before making the transition over to
snow for after midnight and Sunday. All this precip type/wintry
mix determination a low confidence forecast and likely to shift
with subsequent model runs. However, confidence is increasing on
the prolonged and heavy rain event setting up btwn I-70 corridor
and the Ohio River Valley. 2-3 inches of rainfall from Friday
night through Sunday morning will result in an increased flood
risk, particularly with partially frozen ground...already
saturated from recent snowmelt. Flood watch issued with the
forecast from Christian County to Vermilion County and points SE.
Monday bitterly cold on the back side of this system with highs in
the teens... and Monday night sinking into the single digits with light
winds and very little cloud cover. Remains of the forecast left to
the AllBlend for temps, and dry as high pressure returns to the
Midwest until the next systems arrival late Wednesday.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH from late Friday night through late Saturday night
FOR ILZ044>046-052>057-061>063-066>068-071>073.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
415 AM CST THU DEC 19 2013
.DISCUSSION...
328 AM CST
TODAY THROUGH TONIGHT...
OVER THE NEXT SEVERAL DAYS WILL FEATURE A METEOROLOGICAL ROLLER
COASTER...WITH A WIDE RANGE OF TEMPERATURES ABOVE/BELOW
FREEZING...PRECIPITATION CHANGING FROM FROZEN TO LIQUID AND BACK TO
FROZEN...MELTING SNOWPACK WITH POTENTIAL FOR ABUNDANT RAINFALL ON
FROZEN GROUND AND CONSIDERABLE ICE ON AREA STREAMS LEADING TO
POSSIBLY HYDRO CONCERNS. TO FURTHER COMPOUND THE HYDRO CONCERNS WILL
BE THAT IF ICE BREAKS UP ON STREAMS IT MAY EASILY BECOME LOCKED BACK
UP AS SUB-FREEZING AIR RETURNS FOR EARLY NEXT WEEK.
MAIN ITEM ON THE AGENDA FOR TODAY...CAN FOG DEVELOP AND HOW WARM
WILL SFC TEMPS BECOME THIS AFTN. A WEAK SFC LOW NORTHEAST OF THE
STRAITS OF MACKINAW CONTINUES TO PUSH EAST WITH A TRAILING FRONTAL
BOUNDARY STRETCHING WEST THROUGH CENTRAL WISC INTO CENTRAL IOWA.
BROAD ANTI-CYCLONIC FLOW OVER THE CANADIAN PRAIRIES IS SEEPING
SOUTH...AND EXPECTED TO SHARPEN THE BAROCLINIC ZONE ALONG THE
STALLED FRONTAL BOUNDARY.
MAIN CONCERNS FOR TODAY WILL REVOLVE AROUND WHEN/IF FOG CAN
DEVELOP...ALONG WITH STEADILY MOISTENING OF THE NEAR SFC ENVIRONMENT
AS ADDTL MOISTURE ADVECTS NORTH FROM A NEARLY +3 SIGMA V-WIND
COMPONENT INTO AN ABNORMALLY HIGH PWAT REGION OF NORTHERN
IL/NORTHWEST IN. SOUNDINGS HAVE STEADILY OVERDONE MOISTURE...AND
PRESENT T/TD DEPRESSIONS IN PLACES REMAIN IN EXCESS OF 5 DEG TO AS
MUCH AS 10 DEG...WHICH PLACES LESS CONFIDENCE ON THE DEVELOPMENT OF
FOG FOR A FEW HOURS. THERE ARE A FEW LOCATIONS THAT HAVE SOME PATCHY
FOG THIS MORNING...HOWEVER THE COVERAGE IS LIKELY GOING TO REMAIN
LOW. THERMAL BOUNDARY EXISTS FROM MOLINE EAST THROUGH
GARY/VALPO...TO THE NORTH TEMPS ARE IN THE TEENS/20S AND SOUTH THEY
ARE IN THE MID/UPR 30S.
GUIDANCE HAS CONSOLIDATED AROUND LATE MORNING WITH THE BEGINNING
TIMEFRAME FOR DRIZZLE/LGT RA...SO HAVE PUSHED BACK TIMING UNTIL
THEN. TEMPS NORTH OF I-88 WILL LIKELY REMAIN IN THE MID 30S TDY
WHILE SOUTH OF THIS LINE TEMPS SHUD WARM TO ARND 40.
THEN FOR TONIGHT IT APPEARS THE SETUP CONTINUES TO FAVOR FREEZING
RAIN...MAINLY FOR AREAS ALONG AND WEST OF LASALLE TO WAUKEGAN. WEAK
LOW WILL LIFT NORTHEAST ALONG THE BAROCLINIC ZONE WITH THE DEEPER
MOISTURE PEELING OFF TO THE NORTHEAST...WHICH WILL LEAVE IN ITS WAKE
A BAGGY ENVIRONMENT. WITH THE LACK OF LIFT...AND TEMPS HOVERING ARND
FREEZING TO JUST BELOW FREEZING...AND THERMAL PROFILES SHOWING A
CONSIDERABLE WARM LAYER...ANY PRECIP WILL LIKELY BE LGT AND FREEZING
RAIN OR FREEZING DRIZZLE. EAST OF THE AFOREMENTIONED LINE SFC TEMPS
SHUD HOLD RIGHT AT FREEZING OR JUST ABOVE...KEEPING PRECIP IN LIQUID
FORM. NONETHELESS WITH THE GROUND STILL FROZEN FROM THE PAST FEW
WEEKS...UNTREATED SURFACES MAY STILL HAVE SOME SLICK SPOTS.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN FZRA TONIGHT WEST OF LASALLE TO WAUKEGAN...HIGH.
CONFIDENCE IN AREAS EAST OF THIS LINE SEEING FZRA...MEDIUM.
FRIDAY THROUGH SUNDAY...
THE FORECAST AREA WILL CONTINUE TO BE IN A RATHER MOIST
ENVIRONMENT...WITH LINGERING LLVL/MID-LVL MOISTURE IN THE WAKE OF
THE DEPARTING SFC LOW...THUS FRI MORNING MAY CONTINUE TO SEE SPOTTY
FZRA/FZDZ OR LGT SN FOR THE FAR NW. FURTHER EAST TEMPS WILL LIKELY
REMAIN ABOVE FREEZING AND AGAIN ANY PRECIP WILL BE LGT AND RAIN.
SFC RIDGE ACROSS THE NORTHERN PLAINS/UPPER MIDWEST WILL SAG SOUTH
AND BECOME ORIENTED FROM THE CENTRAL PLAINS NORTHEAST TO WESTERN
LAKE SUPERIOR...PLACING THE CONTINUED BAROCLINIC ZONE SOMEWHERE
ACROSS THE CWFA AND BECOMING ORIENTED FROM SW TO NE PERHAPS FROM
LASALLE IL TO KENOSHA WI. TEMPS WILL REMAIN NEARLY STEADY THROUGHOUT
THE DAY IN THE LOW/MID 30S TO PSBLY ARND 40 ACROSS THE FAR SE CWFA.
FOCUS BEYOND FRI WILL BE ON THE HIGHLY ANTICIPATED MID-LVL VORT
MAX...PROGGED TO SLIDE EAST ACROSS THE SOUTHERN ROCKIES INTO WEST
TEXAS FRI NGT. DOWNSTREAM OF THIS FEATURE THE RIDGE WILL BECOME
PARKED ACROSS THE WESTERN ATLANTIC/SOUTHEAST COAST...ALLOWING A
CONSIDERABLE PLUME OF MOISTURE TO ADVECT NORTH THROUGH THE OZARKS
INTO THE TENN/OHIO VALLEY. GUIDANCE HAS BEEN CONSISTENT OVER THE
PAST FEW DAYS WITH AN ABUNDANCE OF PRECIP THROUGHOUT THIS
REGION...THE UNCERTAINTY IS ON HOW FAR NORTH IT WILL STRETCH.
CYCLOGENESIS CONTINUES TO BE PROGGED OVER CENTRAL TEXAS...AND
QUICKLY LIFT NORTH/NORTHEAST SAT TO FAR SOUTHERN IL BY EARLY SUN
MORNING. MODELS WILL LIKELY CONTINUE TO DEMONSTRATE CORRECTIONS OR A
WOBBLE ON THE PRECISE SFC LOW PATH...LARGELY IN PART FROM THE
PRESENT SNOW COVER/BARE GROUND LINE.
AS FOR P-TYPE SAT/SUN...THIS TOO CONTINUES TO EVOLVE WITH THE LATEST
FORECAST SOLUTIONS. THE EC/GFS HAVE SLIGHTLY DIFFERENT IDEAS ON THE
PATH OF THE SYSTEM...WHICH WILL DICTATE WHERE RAIN AND/OR SNOW WILL
FALL. NOT TO MENTION HOW MUCH OF EACH. AT THIS JUNCTURE HAVE OPTED
TO MAINTAIN THE CURRENT THINKING RATHER THAN FLIP-FLOPPING THE
FORECAST...GIVEN THE UNCERTAINTY THAT REMAINS. SOME COOLING DOES
APPEAR TO TAKE SHAPE FOR THE NORTH/NORTHWEST CWFA SAT...WHICH COULD
KEEP TEMPS SUB-FREEZING OR AT FREEZING THROUGHOUT THE DAY SAT.
850MB LOW IS PROGGED TO LIFT NORTHEAST ACROSS THE CWFA...CURRENTLY
SHAPING UP TO BE ALONG A PONTIAC TO CHICAGO LINE. THIS WOULD LIKELY
DISPLACE THE DEFORMATION ZONE TO THE NORTHWEST ACROSS THE FAR NW
CWFA SAT EVENING/EARLY SUN. THERE HAS ALSO BEEN CONSISTENCY IN A DRY
WEDGE LIFTING NE IN THE WAKE OF THE SFC LOW...WHICH COULD FEATURE A
PERIOD OF DRY WX SUN MORNING FOR THE FAR SE CWFA.
FRONTAL BOUNDARY SWEEPS EAST ACROSS THE FORECAST AREA BY MIDDAY
SUN...WITH FLOW BECOMING UNIFORM FROM THE NORTH/NORTHWEST. 500MB
TROUGH AXIS THEN PUSHES OVER THE REGION...WITH ANY LINGERING PRECIP
FALLING AS LGT SNOW SUN AFTN/EVE SETTING THE STAGE FOR LAKE EFFECT
DOWNSTREAM OF LAKE MICHIGAN.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN SNOW REMAINING NW OF LASALLE TO WAUKEGAN THRU SAT
NGT...MEDIUM/HIGH.
MONDAY THROUGH CHRISTMAS DAY...
ENSEMBLES HAVE REMAINED RATHER CONSISTENT WITH A SIMILAR SETUP OF
TWO RIDGES INFLUENCING THE WEATHER PATTERN. ONE BEING PARKED ACROSS
THE EASTERN PACIFIC...THE OTHER OVER THE WESTERN ATLANTIC. THIS
SETUP ALLOWS FOR THE CONTINUED TROUGHING ACROSS THE CENTER OF THE
COUNTY INCLUDING THE GREAT LAKES REGION. HOWEVER BY CHRISTMAS DAY
THESE FEATURES ARE PROGGED TO WEAKEN...WITH MID-LVL FLOW OVER THE
CENTRAL CONUS FLATTENING OUT.
THERE IS SOME INDICATIONS THAT BEYOND CHRISTMAS DAY A HIGH AMPLITUDE
RIDGE WILL BEGIN TO DEVELOP ACROSS FAR WESTERN CANADA...AND COULD
EVENTUALLY DEVELOP A DOWNSTREAM TROUGH YET AGAIN FOR THE GREAT LAKES
REGION LATER NEXT WEEK.
MON/TUE OPERATIONAL SOLUTIONS HAVE A BROAD SFC RIDGE MOVING EAST
ACROSS THE GREAT LAKES REGION AS THE MID-LVL TROUGH AXIS PIVOTS
EAST. THERMAL TROUGH ALOFT WILL LIKELY KEEP TEMPS IN THE TEENS/LOW
20S MON THEN BEGIN TO MODERATE INTO THE 20S BY TUE. WITH THE
AFOREMENTIONED DISCUSSION ON A FLATTENING FLOW...TEMPS MAY RETURN TO
SEASONAL CONDITIONS OR LOW 30S BY CHRISTMAS DAY. MODELS ARE
INDICATING A WEAK MOISTURE STARVED BOUNDARY ARRIVING ACROSS THE
REGION FOR CHRISTMAS DAY...COULD PROVIDE A FEW FLURRIES/LGT SNOW.
CONFIDENCE IN EXTENDED PERIODS...HIGH.
BEACHLER
&&
.HYDROLOGY...
THERE CONTINUES TO BE AN ELEVATED THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* WINDS BCMG EAST IN THE AFTN...ARND 5 KT AT ORD. AT MDW...WINDS
BECOME SOUTHEAST AND REMAIN LIGHT THROUGH THE PERIOD.
* -DZ IS PSBL IN THE AFTN...WITH -RA EXPECTED IN THE EVENING AND
OVERNIGHT. MVFR VSBY IS EXPECTED WITH -DZ AND -RA.
* IFR CIGS ARRIVE BY MID MORNING AND PERSIST THROUGH THE
PERIOD...WITH THE POSSIBILITY OF LIFR CIGS FROM LATE AFTN ON.
JEE
//DISCUSSION...UPDATED 09Z...
MADE A FEW SIGNIFICANT CHANGES TO THE TAFS. PUSHED BACK LOWER VSBY
AND DRIZZLE TO THIS AFTN. IT IS STILL VERY DRY OUT THERE WHICH IS
WHY FOG AND LOW CIGS HAVE NOT DEVELOPED YET. THE CLOSEST MVFR CIGS
ARE OVER MINNESOTA AND SOUTH DAKOTA. A COLD FRONT WILL SINK SOUTH
AND STALL OUT RIGHT BTWN ORD AND MDW. AS SUCH ADJUSTED WINDS IN
THE TAFS.
PREVIOUS DISCUSSION...06Z...
HIGH PRESSURE IS OVER THE SOUTHERN ATLANTIC COAST WHILE
WEAK LOW PRESSURE IS OVER NORTHERN WISCONSIN. THE LOW WILL WEAKEN
AS IT SHIFTS EAST TODAY...WHILE A COLD FRONT PUSHES SOUTH DOWN THE
LAKE. IN THE NEAR TERM WINDS WILL REMAIN OUT OF THE SW AT 10 KT OR
LESS AS THE PRESSURE GRADIENT WEAKENS. PUSHED BACK REDUCED VSBYS
AND IFR CIGS AS OBSERVATIONS SUGGEST IT IS STILL TOO DRY FOR
EITHER TO FORM IN THE NEAR TERM.
MOISTURE INCREASES THROUGH THIS MORNING WITH DRIZZLE POSSIBLY
FORMING EARLY THIS AFTN ALONG WITH IFR CIGS. IN ADDITION TO THE
MOISTURE...FORCING INCREASES BY THE AFTN. STILL NOT ENTIRELY
CONFIDENT IN THE START TIME.
THE COLD FRONT SINKS SOUTH WITH VARIABLE WINDS EXPECTED AHEAD OF
IT AND THEN WINDS SETTLE OUT OF THE EAST TO NORTHEAST BEHIND THE
FRONT. SPEEDS SHOULD BE 10 KT OR LESS. GUIDANCE ALSO HINTS AT THE
POSSIBILITY OF LIFR CIGS...SO PUT IN FEW004 FOR NOW.
PRECIP SPREADS FROM WEST TO EAST THIS EVENING AHEAD OF THE NEXT
LOW. MAY SEE A PERIOD OF -FZDZ AT RFD...BUT NOT ENTIRELY
CONFIDENT AS SURFACE TEMPS WILL BE RIGHT AROUND FREEZING. THE REST
OF THE AREA...AND EVENTUALLY AT RFD...RAIN IS EXPECTED. BETWEEN
THE ABUNDANCE OF LOW LEVEL MOISTURE AND RAIN...KEPT IFR VSBY AND
IFR TO LIFR CIGS GOING OVERNIGHT.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN FORECAST THROUGH 19Z.
* MEDIUM CONFIDENCE IN IFR OR LOWER CIGS OCCURRING...LOW
CONFIDENCE AS TO WHEN THEY ARRIVE AND HOW LOW THEY WILL BE.
* MEDIUM-LOW CONFIDENCE IN OCCURRENCE AND START TIME OF -DZ.
* HIGH CONFIDENCE IN RAIN...MEDIUM CONFIDENCE IN HOW LOW VSBY WILL
BE IN RA.
* MEDIUM CONFIDENCE IN BREAK IN PRECIP EARLY FRIDAY MORNING.
* HIGH CONFIDENCE IN WIND FORECAST.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...IFR WITH A CHANCE OF LIGHT RAIN IN THE MORNING...POSSIBLY
CHANGING BRIEFLY TO LIGHT SNOW BEFORE ENDING IN THE MORNING WITH
IMPROVEMENT TO MVFR. MODERATELY STRONG NE WIND DURING THE DAY.
SATURDAY...MVFR DETERIORATING TO IFR WITH INCREASING THREAT OF
RA/SN/IP/ZR. RAIN LIKELY IN THE EVENING...TURNING TO SNOW
OVERNIGHT WITH POSSIBLE LIFR. MODERATELY STRONG NE WIND RETURN
OVERNIGHT.
SUNDAY...SNOW LIKELY. IFR OCCASIONALLY LIFR...IMPROVING TO MVFR
IN THE EVENING. MODERATELY STRONG NE WIND GRADUALLY BACKING TO
NW.
MONDAY...VFR. MODERATELY STRONG NW WIND GRADUALLY DIMINISHING.
TUESDAY...VFR.
TRS
&&
.MARINE...
414 AM CST
LOW PRESSURE IS OVER THE NORTHERN LAKES THIS MORNING AND IT WILL
WEAKEN AS IT SHIFTS EAST. A COLD FRONT PUSHES DOWN THE LAKE TODAY
AND STALLS OVER SOUTHERN LAKE MICHIGAN THIS AFTERNOON AND
OVERNIGHT. WINDS TURN NORTH AND THEN EAST BEHIND THE FRONT AND
INCREASE TO 15 TO 25 KT...WITH SOUTH WINDS 10 TO 20 KT SOUTH OF THE
FRONT. WINDS FINALLY BECOME UNIFORMLY NORTH TO NORTHEAST FRIDAY
MORNING. AS SUCH THE 15 TO 25 KT WINDS MOVE ALONG THE NEARSHORE
WATERS NORTH OF CALUMET HARBOR EARLY FRIDAY MORNING. HAZARDOUS
WAVES ARE ALSO LIKELY FRIDAY AND POSSIBLY INTO FRIDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED...BUT DID NOT ISSUE ONE
AT THIS TIME. WINDS AND WAVES WILL BE JUST ON THE CUSP OF SMALL
CRAFT CRITERIA...SO DECIDED TO HOLD OFF JUST A LITTLE LONGER ON THE
NEXT SMALL CRAFT ADVISORY.
THE NEXT LOW PASSES SOUTH OF THE LAKE FRIDAY AND IT WEAKENS AS IT
CONTINUES OFF TO THE NORTHEAST. THE GRADIENT WEAKENS AS DO WINDS
WITH EAST WINDS EXPECTED FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE
PASSES TO THE NORTHWEST OF THE LAKE SATURDAY...THEN THE NEXT LOW
PUSHES UP THE OHIO RIVER VALLEY SATURDAY NIGHT INTO SUNDAY. WINDS
INCREASE AND BECOME NORTH SUNDAY THEN NORTHWEST SUNDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED SATURDAY NIGHT THROUGH
MONDAY FOR HIGH WINDS AND WAVES. OVER THE OPEN WATERS...WINDS TO 30
KT ARE EXPECTED. WINDS TURN WEST BEHIND THE LOW MONDAY NIGHT AND
CONTINUE TO WEAKEN AS HIGH PRESSURE MOVES OVER THE WESTERN LAKES
MONDAY NIGHT. INCREASING SOUTH WINDS ARE EXPECTED TUESDAY BETWEEN
THE DEPARTING LOW AND LOW PRESSURE SYSTEM OVER ONTARIO.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
National Weather Service Lincoln IL
343 AM CST Thu Dec 19 2013
.DISCUSSION...
ISSUED 311 AM CST Thu Dec 19 2013
High pressure sliding to the southeastern corner of the country as
a cold front slowly approaches the Midwest. A vigorous wave is
digging in over the southwest and translating into more
southwesterly flow over the region. Temperatures slowly increasing
as the airmass modifies with persistent moisture and warm air
advection. Cold front on the way to move through the area late
tonight and tomorrow morning...eventually stalling invof the Ohio
River Valley. Initial fropa less of an issue, with predominantly
rain for ILX. However, the front will provide a focus for precip
in the southeast...and a path to follow for the next wave ejecting
out of the southwest. Models have been very inconsistent with
track and thermodynamics...and are starting to waiver in the
strength overall. That being said, the trend to a more northerly
track is reflected in the forecast.
SHORT TERM...Today and Tonight...
Warmer as southerly winds usher in temps into the 40s. Overnight
expected to remain mostly above freezing as well. Pops return to
the forecast late this afternoon in the extreme NW as rain makes
its way into Central Illinois. Rain chances continue through the
overnight with the front as the winds slowly shift to
northwesterly behind the front and cooler air filters in. Cold air
not moving in very quickly however as the boundary is relatively
weak/the thermal gradient is less significant. For now, the
initial front is dominated by rain. Problems creep in after
midnight tomorrow night as temperatures finally drop and the
precip changes over to freezing rain for the northern half of the
state.
LONG TERM...Saturday through Wednesday...
Models still a problem, lacking continuity and consistency. Trend
to the north is pronounced enough to be reflected however. This
same trend broadens the developing warm sector and reduces the
coldest air. Ice/freezing rain confined mostly to NW of the
Illinois River Valley for Saturday morning, though a transition to
liquid will likely fall between the valley and the I-55 corridor.
Freezing rain in the NW and rain in the SE will continue through
the afternoon and evening before making the transition over to
snow for after midnight and Sunday. All this precip type/wintry
mix determination a low confidence forecast and likely to shift
with subsequent model runs. However, confidence is increasing on
the prolonged and heavy rain event setting up btwn I-70 corridor
and the Ohio River Valley. 2-3 inches of rainfall from Friday
night through Sunday morning will result in an increased flood
risk, particularly with partially frozen ground...already
saturated from recent snowmelt. Flood watch issued with the
forecast from Christian County to Vermilion County and points SE.
Monday bitterly cold on the back side of this system with highs in
the teens... and Monday night sinking into the single digits with light
winds and very little cloud cover. Remains of the forecast left to
the AllBlend for temps, and dry as high pressure returns to the
Midwest until the next systems arrival late Wednesday.
HJS
&&
.AVIATION...
ISSUED 1110 PM CST Wed Dec 18 2013
Little change from earlier thinking this evening, the main
challenge will be timing of the IFR/LIFR cigs and vsbys into
the forecast area on Thursday. Tight pressure gradient over
the state this evening resulted in rather gusty south winds.
The surface winds are expected to diminish some during the
early morning hours, however, the latest short term forecasts
suggest the LLWS in the 1500 ft level will continue thru 12z.
A cold front over the northwest half of Iowa will push to the
Mississippi River by dawn Thursday and then slowly edge east
into our area during the day. The persistent southerly winds
will aid in transporting higher moisture northeast over the
colder/snow covered areas of central IL, which will lead to
widespread low cigs and vsbys, especially during the afternoon
and evening. Confidence on the timing of the lower cigs and
vsbys in our area is not that great at this time as most models
have been too aggressive in developing the IFR cigs and vsbys.
However, the HRRR model has been quite consistent in keeping
the low cigs out thru the morning with development taking place
by afternoon from west to east. Will tend to lean more on that
model`s timing at this point.
Surface winds will remain out of the south at 12 to 17 kts into
the early morning hours with a gradual decrease in the sustained
winds by morning. Southerly winds will hold over the area thru
Thursday with speeds of 8 to 13 kts. Forecast soundings indicate
the potential for some light rain or drizzle with the lower cigs
and vsbys Thursday evening.
Smith
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1206 AM CST THU DEC 19 2013
.DISCUSSION...
810 PM CST
FOR EVENING UPDATE...
MAIN SHORT TERM FORECAST CONCERNS FOCUS ON TEMPERATURE TRENDS WITH
BREEZY SOUTH WINDS AND WARM ADVECTION...AND CLOUD TRENDS WITH MODEL
FORECASTS CONTINUING TO DEPICT STRATUS DEVELOPMENT OVERNIGHT. HAVE
MADE SOME MINOR CHANGES TO GOING FORECAST TO LOWER MIN TEMPS A BIT
ESPECIALLY ACROSS NORTH CENTRAL IL WHERE THEY/VE FALLEN OFF THIS
EVENING...AND TO REDUCE SKY COVER A BIT UNTIL LATE/TOWARD MORNING.
SURFACE LOW PRESSURE WAS OVER NORTHERN WISCONSIN AT 02Z/8 PM CST IN
ASSOCIATION WITH A QUICK MOVING SHORT WAVE PROPAGATING ACROSS THE
UPPER MISSISSIPPI VALLEY AND NORTHERN LAKES REGION. TIGHT PRESSURE
GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEASTERN
STATES HAS RESULTED IN BREEZY SOUTH-SOUTHWEST WINDS ACROSS THE
REGION...ESPECIALLY ACROSS THE SOUTH/EAST CWA AT THIS HOUR CLOSER TO
WHERE STRONGER SURFACE PRESSURE FALLS WERE OCCURRING NOW OVER LOWER
MICH/INDIANA/OH. WINDS HAVE KEPT TEMPS NEARLY STEADY OR EVEN TO RISE
A DEGREE OR TWO...EXCEPT OVER NORTH CENTRAL IL WHERE WEAKENING
GRADIENT/WINDS AND MOSTLY CLEAR SKIES HAVE ALLOWED TEMPS TO FALL A
FEW DEGREES. EXPECT THIS WILL CONTINUE TO BE THE CASE OVERNIGHT AS
WINDS CONTINUE TO DIMINISH FROM THE NORTHWEST...AS SURFACE COLD
FRONTAL TROUGH SLOWLY APPROACHES BEHIND NORTHERN LAKES LOW. EXPECT
TO SEE TEMPS REMAIN FAIRLY STEADY NORTHWEST OVERNIGHT...RISING A BIT
IN THE EAST/SOUTHEAST COUNTIES AND LIKELY STAYING ABOVE FREEZING.
AS FOR CLOUDS...ONLY SOME PATCHY HIGH CIRRUS ACROSS THE REGION AT
THIS TIME. VARIOUS MODELS CONTINUE TO INDICATE DEVELOPMENT OF LOW
STRATUS FROM NORTHERN/NORTHWEST IL BACK INTO MISSOURI BY LATE
EVENING...THOUGH UPSTREAM 00Z SOUNDINGS FROM DVN/ILX/SGF/TOP ALL
VERY DRY IN THE LOW/MID LEVELS AND SUSPECT MODELS ARE OVER-DONE WITH
STRATUS AND POTENTIAL FOG DEVELOPMENT OVERNIGHT. GFS MAV GUIDANCE
MAY HAVE THE RIGHT IDEA...OF HOLDING OFF LOW CLOUD DEVELOPMENT LATER
THURSDAY...WHEN COLD FRONT STALLS ACROSS AREA AND HELPS TO POOL LOW
LEVEL MOISTURE ALONG IT. THEREFORE HAVE REDUCED SKY COVER PERCENTAGE
IN HOURLY GRIDS THROUGH 09Z OR SO...WITH INCREASING CLOUDINESS THEN
INTO THURSDAY MORNING.
RATZER
//PREV DISCUSSION...
305 PM CST
SHORT TERM (THROUGH FRIDAY NIGHT)...
STRENGTHENING SOUTHERLY WINDS ACROSS THE IN RESPONSE TO A
CLIPPER-LIKE SYSTEM TRACKING EAST ACROSS THE UPPER MISSISSIPPI
VALLEY HAS BEGUN THE PROCESS OF DRAGGING LOW LEVEL MOISTURE
NORTHWARD INTO MISSOURI AND IOWA. FARTHER EAST OVER OUR CWA
DEWPOINTS HAVE BEEN SLOW TO COME UP...WITH MODELS NOT HANDLING THE
RETURN OF LOW LEVEL MOISTURE PARTICULARLY WELL. OBSERVATIONAL TRENDS
THUS FAR TODAY ARE REALLY BEGINNING TO RAISE SOME SERIOUS DOUBTS
ABOUT THE TIMING OF THE DEVELOPMENT OF STRATUS AND POTENTIALLY FOG
ACROSS THE AREA. FORECAST SOUNDINGS FROM THE NAM AND GFS WOULD
SUGGEST STRATUS OVER THE AREA BY MID EVENING. MODELS SAY THAT THIS
STRATUS "SHOULD" BE BLOSSOMING OVER IOWA AND MISSOURI IN THE NEXT
HOUR OR TWO...BUT WITH SURFACE DEWPOINT DEPRESSIONS OF 10-15F OVER
THE SNOW PACK AND 20F+ JUST UPSTREAM I SUSPECT THIS PROCESS WILL BE
MUCH SLOWER THAN FORECAST BY THE MODELS. GIVEN DEWPOINTS JUST BARELY
FORECAST TO REACH FREEZING AND PROBABLY NOT UNTIL LATE
TONIGHT...SNOW MELT WONT BE A HUGE FACTOR TOWARD ADDING LOW LEVEL
MOISTURE AND AM PLANNING TO PUSH BACK STRATUS IN THE GRIDS AND
REMOVE DRIZZLE AND FOG TONIGHT.
AS CLIPPER TRACKS RAPIDLY EAST INTO THE NE CONUS ON THURSDAY A COLD
FRONT TRAILING WEST FROM THE LOW WILL BEGIN TO SAG SLOWLY SOUTHWARD
BECOMING INCREASINGLY ALIGNED WITH THE MID-UPPER LEVEL FLOW AND
LIKELY STALLING OUT OVER NORTHERN ILLINOIS THURSDAY. WEAK SHORTWAVE
EMANATING OUT OF THE AMPLIFYING WESTERN CONUS TROUGH WILL ENCOURAGE
A WEAK WAVE OF LOW PRESSURE TO TRACK NORTHEAST ALONG THE STALLED OUT
FRONT INTO CENTRAL ILLINOIS AND NORTHERN INDIANA THURSDAY NIGHT INTO
FRIDAY. LOW LEVEL BAROCLINIC ZONE WILL STRENGTHEN IN ADVANCE OF THIS
WAVE THURSDAY NIGHT WITH BACKING LOW LEVEL FLOW RESULTING IN
INCREASING ISENTROPIC ASCENT. ANTICIPATE LIGHT RAIN TO BREAK OUT
ALONG AND NORTH OF THIS SURFACE BOUNDARY ACROSS MUCH OF THE CWA LATE
THURSDAY AFTERNOON AND PARTICULARLY THURSDAY NIGHT. MODELS REMAIN
IN GREAT AGREEMENT IN KEEPING DEPTH OF MOISTURE SOMEWHAT SHALLOW
WITH FAIRLY DEEP LAYER OF DRY AIR IN THE MID LEVELS WHICH. THIS
DRY AIR ALOFT WILL LIKELY RESULT IN LITTLE/NO ICE BEING PRESENT IN
THE CLOUDS SO PRECIP FALLING SHOULD BE ALL LIQUID (DRIZZLE/LIGHT
RAIN).
STRENGTHENING NORTH WINDS TO THE NORTH OF THE BOUNDARY AND RESULTANT
COLD AIR ADVECTION LOOK TO SEND SFC TEMPS DROPPING BELOW FREEZING
THURSDAY NIGHT FROM THE NORTHERN SUBURBS WEST INTO NORTH CENTRAL
ILLINOIS. DESPITE ONLY SLIGHT LAYER OF ABOVE FREEZING TEMPS...THE
EXPECTED LACK OF ICE IN THE CLOUDS SHOULD RESULT IN A SWITCH OVER TO
LIGHT FREEZING RAIN AS TEMPS DROP BELOW FREEZING THURSDAY NIGHT.
WHILE QPF WILL BE LIGHT...ANY AMOUNT OF FREEZING RAIN IS ENOUGH TO
CAUSE PROBLEMS. LATER FORECASTS WILL PROBABLY HAVE TO FINE TUNE
THE LOCATION OF THE FREEZING LINE...BUT WOULD ANTICIPATE THAT A
FREEZING RAIN ADVISORY WILL EVENTUALLY BE NEEDED FOR AREAS MAINLY
WEST AND NORTH OF CHICAGO THURSDAY NIGHT INTO FRIDAY MORNING.
THE WEAK WAVE OF LOW PRESSURE WILL RIPPLE EAST OF THE AREA AND ALLOW
THE FRONT TO SAG A BIT SOUTH IN ITS WAKE FRIDAY. FORCING GENERALLY
LOOKS WEAK AND UNIMPRESSIVE...BUT GLOBAL MODELS INSIST ON SQUEEZING
OUT A FEW HUNDREDTHS OF AN INCH OF ADDITIONAL QPF FRIDAY. HAVE OPTED
TO HANG ON TO SOME VERY LOW CHANCE POPS FRIDAY INTO FRIDAY
NIGHT...BUT GENERALLY THINK THAT PRECIP SHOULD SHUT DOWN UNTIL THE
BIG BOY TO OUR SOUTHWEST COMES BARRELING OUT TOWARD THE AREA OVER
THE WEEKEND.
IZZI
THE BIG WEEKEND STORM...SATURDAY INTO SUNDAY...
A MAJOR PRECIPITATION EVENT IS BECOMING MORE LIKELY ACROSS THE AREA
LATE SATURDAY AND INTO SUNDAY.
WATER VAPOR IMAGERY SHOWS OUR DISTURBANCE OF INTEREST CURRENTLY
DIGGING SOUTHWARD JUST OFF THE WASHINGTON OREGON COAST. GUIDANCE
CONTINUES TO DIG THIS PV ANOMALY ACROSS THE SOUTHWEST..NEAR BAJA
CALIFORNIA BY FRIDAY EVENING. MEANWHILE...THE QUASI-ZONAL FLOW
PATTERN...CURRENTLY IN PLACE ACROSS MOST OF THE CONUS WILL QUICKLY
TRANSITION INTO A SOUTHWESTERLY FLOW PATTERN ALOFT...AS THIS SYSTEM
CONTINUES TO DIG ACROSS THE WEST. THE ASSOCIATED STRONG DOWNSTREAM
HEIGHT RISES WILL ULTIMATELY SET UP AN IMPRESSIVE ~590DM 500 MB HIGH
OFF THE FLORIDA COAST BY EARLY SATURDAY.
THE LATEST GUIDANCE IS NOW BEGINNING TO TREND TOWARDS A BETTER
DEVELOPED SURFACE LOW ACROSS THE MID MISSISSIPPI VALLEY AND
GREAT LAKES REGION...RATHER THAN A MORE ELONGATED SURFACE SYSTEM.
THIS APPEARS TO BE DUE TO THE FACT THAT THE NEGATIVELY TILTED MID
LEVEL IMPULSE MAY NOT ENCOUNTER AS MUCH CONFLUENT FLOW...AS
PREVIOUSLY THOUGHT...AS IT LIFTS NORTHEASTWARD TOWARDS THE MID
MISSISSIPPI VALLEY..THUS NOT SHEARING THE WAVE OUT AS QUICKLY ACROSS
THE AREA. IN ADDITION...LOWER LEVEL PV ANOMALIES...LIKELY ASSOCIATED
WITH CONVECTIVE ACTIVITY TO THE SOUTH...SHOULD HELP TO ONLY DEEPEN
THE LOW. AS SUCH...A STRONGER AND MORE NORTHWEST TRACK APPEARS TO BE
THE WAY TO GO AT THIS TIME...THOUGH THERE IS STILL TIME FOR CHANGES
IN THE TRACK OF THE SYSTEM AS IT GETS BETTER SAMPLED BY THE RAOB
NETWORK.
OVERALL...THIS INCREASES THE LIKELIHOOD OF MORE RAIN ACROSS MOST OF
NORTHERN ILLINOIS AND DECREASES CHANCES OF SIGNIFICANT ICE AND SNOW.
STRONG MOISTURE CONVERGENCE AND FRONTOGENESIS ALONG THE NOSE OF A 60
KT SOUTHERLY LOW LEVEL JET WILL QUICKLY PUMP IN ANOMALOUS AMOUNTS OF
MOISTURE. MOST GUIDANCE IS SUGGESTING PWATS NEAR AND EVEN IN EXCESS
OF AN INCH ARE LIKELY ACROSS MOST OF THE AREA BY SATURDAY EVENING.
THIS IS ABOUT 300% OF NORMAL FOR THIS TIME OF YEAR. THIS SHOULD
SUPPORT A LARGE SWATH OF RAINFALL TO LIFT NORTHWARD ACROSS MY
SOUTHERN COUNTIES DURING THE DAY SATURDAY...POSSIBLY GETTING INTO
NORTHERN ILLINOIS AS EARLY AS SATURDAY AFTERNOON. THE PRECIP COULD
INITIAL BEGIN AS SOME SLEET OR LIGHT SNOW...ESPECIALLY ACROSS
NORTHERN ILLINOIS LATE SATURDAY...BUT CONTINUED WARM ADVECTION
SHOULD WARM TEMPS ENOUGH TO RESULT IN MAINLY RAIN IN THE CHICAGO
AREA FOR SATURDAY NIGHT. THE BIG AREAS OF POSSIBLE CONCERN WILL BE
ACROSS NORTH CENTRAL ILLINOIS...WHERE MARGINAL THERMAL PROFILES
COULD STILL SUPPORT A MIX OF SNOW...SLEET AND EVEN SOME FREEZING
RAIN.
OTHERWISE...THE MAIN STORY WILL BE THE GOOD POTENTIAL FOR
SIGNIFICANT RAINFALL ACROSS THE SOUTHERN HALF OF THE AREA.
INDICATIONS CONTINUE TO POINT TO AT LEAST 2 TO 3 INCH RAINFALL
AMOUNTS ACROSS MY EAST CENTRAL ILLINOIS AND NORTHWESTERN INDIANA
COUNTIES. THIS COMBINED WITH THE 0.5 TO 0.75 INCHES CURRENTLY IN THE
SNOW PACK...AND A FROZEN GROUND...COULD LEAD TO SOME SIGNIFICANT
FLOODING CONCERNS SATURDAY NIGHT INTO SUNDAY.
FINALLY AS THE MID LEVEL WAVE MOVES ACROSS THE AREA AND THE SURFACE
LOW MOVES ACROSS LOWER MICHIGAN ON SUNDAY...A DEFORMATION BAND OF
SNOW IS LIKELY...POSSIBLY HEAVY. HOWEVER...DEPENDING ON THE ULTIMATE
TRACK OF THIS SYSTEM...THE BETTER CHANCES MAY REMAIN PRIMARILY
ACROSS EASTERN IOWA AND NORTHWESTERN AND NORTH CENTRAL ILLINOIS AND
POINTS NORTHEAST. THE PROSPECTS OF A DRY SLOT PUSHING IN ACROSS
NORTHEASTERN ILLINOIS AND NORTHWESTERN INDIANA MAY RESULT IN ONLY
LIGHT PRECIP ON SUNDAY...IF ANY AT ALL. FOR NOW I HAVE CONTINUED
WITH LIKELY POPS ACROSS THE AREA...BUT IF THIS DRY SLOT DOES PUSH
ACROSS THE AREA ON SUNDAY...MUCH OF NORTHEAST AND EAST CENTRAL
ILLINOIS AND NORTHWEST INDIANA MAY NOT SEE MUCH ADDITIONAL PRECIP
SUNDAY.
KJB
LONG TERM...SUNDAY NIGHT THROUGH CHRISTMAS DAY...
SUNDAY NIGHT...
A SHOT OF VERY COLD AIR WILL FOLLOW THE BIG WEEKEND STORM FOR EARLY
NEXT WEEK AS A 1035 TO 1040 MB HIGH BUILDS SOUTH FROM THE NORTHERN
PLAINS. ALL OF THE SYSTEM SNOWS SHOULD BE OFF TO THE EAST SUNDAY
NIGHT...BUT POSITIVE VORTICITY ADVECTION FROM SHORT WAVES ROTATING
AROUND DEEP UPPER TROUGH OVER THE REGION COULD SQUEEZE OUT SOME
LIGHT SNOW OR FLURRIES IN THE ARCTIC AIR MASS. THE 12Z ECMWF IS
MOST BULLISH WITH THIS SCENARIO IN SQUEEZING OUT LIGHT QPF OVER
THE AREA. TEMPERATURES WILL PLUMMET IN STRONG COLD ADVECTION/H85
TEMPS COOLING TO THE MID MINUS TEENS CELSIUS/BUT PERSISTENT NW
WINDS AND CLOUD COVER COULD LIMIT HOW FAR THEY FALL. WITH THE
RAPIDLY FALLING TEMPERATURES SUNDAY NIGHT...ANY REMAINING MOISTURE
ON THE GROUND WILL LIKELY FREEZE QUICKLY.
MONDAY...
ADDED A SLIGHT CHANCE OF FLURRIES ON MONDAY MORNING AS THE DEEP
UPPER TROUGH WILL BE OVERHEAD AND IT MAY NOT BE HARD TO SQUEEZE OUT
DENDRITES DESPITE THE COLD DRY AIRMASS. WILL ALSO HAVE TO WATCH FOR
WIND DIRECTION TRENDS ACROSS LAKE MICHIGAN WITH A FAVORABLE
THERMODYNAMIC SET UP FOR LAKE EFFECT SNOW. HIGH TEMPERATURES
MONDAY AND LOWS MONDAY NIGHT WILL BE COLD EVERYWHERE...BUT HOW
COLD WILL DEPEND ON WHICH AREAS MAINTAIN MOST OF THEIR SNOW COVER
AFTER THE WEEKEND SYSTEM. AT THIS TIME...IT APPEARS THAT THE
NORTHERN CWA WOULD HAVE THE BEST CHANCE AND THE SOUTHEAST CWA THE
LOWEST CHANCE. WITH POTENTIAL FOR SURFACE RIDGE AXIS TO BE OVER
THE AREA...COULD CERTAINLY ENVISION SNOW COVERED AREAS DIPPING TO
AT LEAST A FEW DEGREES BELOW ZERO.
TUESDAY NIGHT AND WEDNESDAY...
AFTER A VERY COLD START TO CHRISTMAS EVE DAY...SOUTHWEST WARM
ADVECTION BEHIND TROUGH DEPARTING TO THE EAST WILL ENABLE AFTERNOON
TEMPERATURES TO RECOVER FAIRLY NICELY. COULD SEE TEMPERATURES BEING
A BIT WARMER THAN CURRENTLY FORECAST IN AREAS WITHOUT SNOWCOVER.
THEN LOOKING OUT TO CHRISTMAS DAY...MEDIUM RANGE GUIDANCE SHOWS A
CLIPPER SYSTEM SCOOTING THROUGH THE UPPER LAKES. THE 12Z ECMWF
INDICATES AN UPPER WAVE IN ASSOCIATION WITH THE COLD FRONT TRAILING
FROM THE CLIPPER. IF THIS WERE TO OCCUR...THERE COULD BE SOME LIGHT
SNOW OR FLURRIES IN THE AIR ON CHRISTMAS DAY...A MINOR CONSOLATION
PRIZE TO EVERYONE WANTING A WHITE CHRISTMAS IN AREAS THAT MAY LOSE
MOST OR ALL OF THEIR SNOWPACK THIS WEEKEND. HAVE MAINTAINED A DRY
FORECAST PER GUIDANCE BLEND INITIALIZATION FOR NOW...BUT ONE CAN
ONLY HOPE.
RC
&&
.HYDROLOGY...309 PM CST
THERE LOOKS TO BE AN INCREASING THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* LLWS PERSISTS THROUGH 09Z.
* WINDS BCMG EAST IN THE AFTN...ARND 5 KT.
* -DZ IS PSBL IN THE AFTN...WITH -RA EXPECTED IN THE EVENING AND
OVERNIGHT. MVFR TO IFR VSBY IS EXPECTED WITH -DZ AND -RA.
* IFR CIGS ARRIVE BY MID MORNING AND PERSIST THROUGH THE
PERIOD...WITH THE POSSIBILITY OF LIFR CIGS FROM LATE AFTN ON.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS OVER THE SOUTHERN ATLANTIC COAST WHILE WEAK LOW
PRESSURE IS OVER NORTHERN WISCONSIN. THE LOW WILL WEAKEN AS IT
SHIFTS EAST TODAY...WHILE A COLD FRONT PUSHES SOUTH DOWN THE LAKE.
IN THE NEAR TERM WINDS WILL REMAIN OUT OF THE SW AT 10 KT OR LESS
AS THE PRESSURE GRADIENT WEAKENS. PUSHED BACK REDUCED VSBYS AND
IFR CIGS AS OBSERVATIONS SUGGEST IT IS STILL TOO DRY FOR EITHER TO
FORM IN THE NEAR TERM.
MOISTURE INCREASES THROUGH THIS MORNING WITH DRIZZLE POSSIBLY
FORMING EARLY THIS AFTN ALONG WITH IFR CIGS. IN ADDITION TO THE
MOISTURE...FORCING INCREASES BY THE AFTN. STILL NOT ENTIRELY
CONFIDENT IN THE START TIME.
THE COLD FRONT SINKS SOUTH WITH VARIABLE WINDS EXPECTED AHEAD OF
IT AND THEN WINDS SETTLE OUT OF THE EAST TO NORTHEAST BEHIND THE
FRONT. SPEEDS SHOULD BE 10 KT OR LESS. GUIDANCE ALSO HINTS AT THE
POSSIBILITY OF LIFR CIGS...SO PUT IN FEW004 FOR NOW.
PRECIP SPREADS FROM WEST TO EAST THIS EVENING AHEAD OF THE NEXT
LOW. MAY SEE A PERIOD OF -FZDZ AT RFD...BUT NOT ENTIRELY
CONFIDENT AS SURFACE TEMPS WILL BE RIGHT AROUND FREEZING. THE REST
OF THE AREA...AND EVENTUALLY AT RFD...RAIN IS EXPECTED. BETWEEN
THE ABUNDANCE OF LOW LEVEL MOISTURE AND RAIN...KEPT IFR VSBY AND
IFR TO LIFR CIGS GOING OVERNIGHT.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN FORECAST THROUGH 15Z.
* MEDIUM-HIGH CONFIDENCE IN IFR OR LOWER CIGS OCCURRING...LOW
CONFIDENCE AS TO WHEN THEY ARRIVE AND HOW LOW THEY WILL BE.
* MEDIUM CONFIDENCE IN OCCURRENCE AND START TIME OF -DZ.
* HIGH CONFIDENCE IN RAIN...MEDIUM CONFIDENCE IN 1 SM VSBY IN RA
AS IT COULD BE HIGHER VSBY.
* MEDIUM CONFIDENCE IN BREAK IN PRECIP EARLY FRIDAY MORNING.
* HIGH CONFIDENCE IN WIND FORECAST.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...IFR WITH A CHANCE OF LIGHT RAIN IN THE MORNING...POSSIBLY
CHANGING BRIEFLY TO LIGHT SNOW BEFORE ENDING IN THE MORNING WITH
IMPROVEMENT TO MVFR. MODERATELY STRONG NE WIND DURING THE DAY.
SATURDAY...MVFR DETERIORATING TO IFR WITH INCREASING THREAT OF
RA/SN/IP/ZR. RAIN LIKELY IN THE EVENING...TURNING TO SNOW
OVERNIGHT WITH POSSIBLE LIFR. MODERATELY STRONG NE WIND RETURN
OVERNIGHT.
SUNDAY...SNOW LIKELY. IFR OCCASIONALLY LIFR...IMPROVING TO MVFR
IN THE EVENING. MODERATELY STRONG NE WIND GRADUALLY BACKING TO
NW.
MONDAY...VFR. MODERATELY STRONG NW WIND GRADUALLY DIMINISHING.
TUESDAY...VFR.
TRS
&&
.MARINE...
137 PM CST
THE VERY ACTIVE...BUT CHANGEABLE...PATTERN WILL CONTINUE OVER LAKE
MICHIGAN FOR THE NEXT SEVERAL DAYS. LOW PRESSURE MOVING ACROSS THE
UPPER MISSISSIPPI VALLEY AS HIGH PRESSURE SETTLES INTO THE SERN
CONUS IS SETTING UP A STRONG SOUTHERLY GRADIENT OVER LAKE MICHIGAN.
WINDS ARE ALREADY ON THE INCREASE AND EXPECT THAT THE SOUTH WINDS
SHOULD REACH GALE FORCE BY LATE THIS AFTERNOON OR EARLY THIS
EVENING. THE STRONGEST GRADIENT WILL BE OVER THE SOUTHERN PORTIONS
OF THE LAKE AND GALES MAY TOP OUT AT AROUND 40KT...WHEREAS GALES
WILL BE CLOSER TO 35KT OVER THE NORTHERN PORTIONS OF THE LAKE. THE
LOW WILL CROSS THE UPPER GREAT LAKES TONIGHT AND THURSDAY WHILE
DRAGGING A STRONG COLD FRONT DOWN THE LAKE. THE FRONT IS EXPECTED
TO GO STATIONARY OVER THE SOUTHERN TIP OF THE THURSDAY NIGHT...AND
WHILE WINDS OVER MUCH OF THE LAKE NORTH OF A MILWAUKEE TO HOLLAND
LINE SHOULD BECOME NORTHEASTERLY AT 25-30KT...WINDS OVER THE FAR
SOUTHERN TIP OF THE LAKE WILL REMAIN MORE SOUTHERLY AND WEAKER. BY
THURSDAY NIGHT...HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS
WILL FINALLY HELP THE FRONT PUSH SOUTH OF THE LAKE. BY THURSDAY
MORNING...A LOW PRESSURE SYSTEM IS EXPECTED TO DROP OUT OF THE
CENTRAL ROCKIES AND INTO THE SOUTH HIGH PLAINS AS A WARM FRONT
FORMS...EXTENDING NORTHEAST THROUGH NORTHERN MISSOURI AND INTI
NORTHERN ILLINOIS. WAVES OF LOW PRESSURE WILL RIPPLE ALONG THE WARM
FRONT...AS ANOTHER AREA OF HIGH PRESSURE SLIDES INTO THE NORTHERN
PLAINS. WITH A RIDGE OF HIGH PRESSURE EXTENDING FROM THE CENTRAL
PLAINS THROUGH THE UPPER GREAT LAKES AND INTO QUEBEC...A PERSISTENT
NELY TO ELY FETCH WILL SET UP OVER THE LAKE FROM THURSDAY NIGHT
THOUGH FRIDAY NIGHT. WHILE GALES ARE NOT EXPECTED AT THIS TIME WITH
THE BRISK NELY FLOW...WINDS MAY APPROACH 30KT THURSDAY NIGHT INTO
FRIDAY MORNING. THERE IS STILL SOME UNCERTAINTY AS THE EXACT TRACK
OF THE LOW DEVELOPING OVER THE SOUTH HIGH PLAINS...BUT THE GENERAL
CONSENSUS IS THAT IT SHOULD PASS TO THE SOUTH OF LAKE MICHIGAN
SUNDAY MORNING AND THE PROCEED NORTHEAST INTO SOUTHERN QUEBEC BY
MONDAY MORNING. YET ANOTHER AREA OF STRONG HIGH PRESSURE WILL BUILD
OUT OF CANADA AND INTO THE PLAINS FOLLOWING THE PASSAGE OF THE LOW.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 2 AM
THURSDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Lincoln IL
1114 PM CST Wed Dec 18 2013
.DISCUSSION...
ISSUED 825 PM CST Wed Dec 18 2013
Tight pressure gradient over central Illinois this evening has
kept the gusty southerly winds going thru much of the area. Had
a wind gust up to 40 mph in Danville over the past hour with
many areas seeing sustained winds of 20 to 25 mph this evening.
This should help keep temps steady or even slowly rising later
tonight as the winds only slowly decrease in advance of a cold
front still well west of our area. As of 02z, the front was
analyzed over western Iowa and will gradually work its way east
overnight. Surface dew points were gradually increasing to our
south and west this evening, with most of the 40 and 50 degree
dew points still well southwest of area over parts of central
Texas.
As the cold front slips south and east towards eastern Iowa
by morning, our wind speeds will decrease and with the persistent
advection of higher dew point air over the snow covered areas
in central Illinois, we should develop some low level cloud cover
and possibly some fog, especially across our far northwest, which
will be closer to the approaching cold front. A zone update was
sent out earlier in the evening to address the stronger winds
over the forecast area with the remainder of the forecast still
holding, so no additional update will be needed at this time.
Smith
&&
.AVIATION...
ISSUED 1110 PM CST Wed Dec 18 2013
Little change from earlier thinking this evening, the main
challenge will be timing of the IFR/LIFR cigs and vsbys into
the forecast area on Thursday. Tight pressure gradient over
the state this evening resulted in rather gusty south winds.
The surface winds are expected to diminish some during the
early morning hours, however, the latest short term forecasts
suggest the LLWS in the 1500 ft level will continue thru 12z.
A cold front over the northwest half of Iowa will push to the
Mississippi River by dawn Thursday and then slowly edge east
into our area during the day. The persistent southerly winds
will aid in transporting higher moisture northeast over the
colder/snow covered areas of central IL, which will lead to
widespread low cigs and vsbys, especially during the afternoon
and evening. Confidence on the timing of the lower cigs and
vsbys in our area is not that great at this time as most models
have been too aggressive in developing the IFR cigs and vsbys.
However, the HRRR model has been quite consistent in keeping
the low cigs out thru the morning with development taking place
by afternoon from west to east. Will tend to lean more on that
model`s timing at this point.
Surface winds will remain out of the south at 12 to 17 kts into
the early morning hours with a gradual decrease in the sustained
winds by morning. Southerly winds will hold over the area thru
Thursday with speeds of 8 to 13 kts. Forecast soundings indicate
the potential for some light rain or drizzle with the lower cigs
and vsbys Thursday evening.
Smith
&&
.PREV DISCUSSION...
ISSUED 256 PM CST Wed Dec 18 2013
Forecast problem is the complicated precipitation types with the
next frontal system to move into region Friday and produce pcpn
through the weekend.
SHORT TERM...Tonight through Friday night.
Upper air and moisture channel this morning shows main trough off
the west US that will move to the east and affect region by
weekend. Models have become very similar now in the movement of
the cold front into the plains, warming in the low levels ahead of
the front for Thursday and the front slipping into IL Thurs night
through Friday, with some light overrunning pcpn behind the front.
Main pcpn though with be in response to the southwest US upper low
coming out and producing major lift over the front into OH and mid
MS valleys.
LONG TERM...Saturday through Wednesday.
As the system moves out of the southern plains, pcpn develops
Friday night and spreads north into central IL Saturday. Looking
at all the models forecast soundings, have modified pcpn types
toward a little warmer conditions and so tried to push the
freezing rain chances further to the northwest, decreasing the
amount of ice in the central sections, but still with some
possible ice in the northern parts of central IL. Rain Saturday
and overnight will be the main issue with the southeast sections
possibly getting as much as 3 inches storm total. On Sunday, the
deformation should set up northwest of the CWA, with some snow
amounts in the northwest sections before ending.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1155 PM MST WED DEC 18 2013
.UPDATE...
ISSUED AT 748 PM MST WED DEC 18 2013
SEEING A LOT OF VARIABILITY WITH HOURLY TEMPERATURES TONIGHT WITH
A FEW SITES ALREADY DROPPING TO AROUND FREEZING...BUT THEN RISING
AGAIN AS HIGH CLOUDS MOVE OVER. TRIED TO ACCOUNT FOR THIS
VARIABILITY...BUT GIVEN THE DEGREE OF CHANGE GETTING A PERFECT
CURVE WILL BE DIFFICULT. DESPITE THE INITIAL DROP...CURRENT
FORECAST LOOKS ON TRACK WITH ONLY A FEW MINOR CHANGES MADE. LOOKS
LIKE FRONT WILL BEGIN TO IMPACT AREA IN THE MORNING BUT STRONGEST
PUSH OF COLD AIR WILL OCCUR JUST AFTER 18Z.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 1148 PM MST WED DEC 18 2013
NORTHWEST FLOW WILL BE THE MAJOR THEME IN THE LONG TERM PERIOD. A
COUPLE OF SHORTWAVE DISTURBANCES WILL MOVE THROUGH AND BRING BRIEF
COOL DOWNS KEEPING TEMPERATURES NEAR CLIMATOLOGICAL NORMALS. THERE
WILL BE SOME WEAK FORCING WITH EACH WAVE...BUT PRECIPITATION
CHANCES APPEAR SLIM TO NONE WITH ONLY LIMITED LOW LEVEL MOISTURE
AVAILABLE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1154 PM MST WED DEC 18 2013
VFR CONDITIONS WITH CLOUDY THROUGH THE TAF PERIOD AT MCK AND GLD.
EXPECT WINDS TO INCREASE AND SHIFT TO THE EAST/NORTHEAST FOLLOWING
THE PASSAGE OF A COLD FRONT AT MCK AND THEN GLD AFTER ABOUT 15Z.
EXPECT CEILINGS TO DROP...BUT REMAIN VFR WITH THE ADVANCE OF THE
MUCH COLDER PUSH BETWEEN 01Z-03Z. WINDS WILL ALSO BECOME GUSTY OUT
OF THE NORTH AT THAT TIME.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...024
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1153 PM MST WED DEC 18 2013
.UPDATE...
ISSUED AT 748 PM MST WED DEC 18 2013
SEEING A LOT OF VARIABILITY WITH HOURLY TEMPERATURES TONIGHT WITH
A FEW SITES ALREADY DROPPING TO AROUND FREEZING...BUT THEN RISING
AGAIN AS HIGH CLOUDS MOVE OVER. TRIED TO ACCOUNT FOR THIS
VARIABILITY...BUT GIVEN THE DEGREE OF CHANGE GETTING A PERFECT
CURVE WILL BE DIFFICULT. DESPITE THE INITIAL DROP...CURRENT
FORECAST LOOKS ON TRACK WITH ONLY A FEW MINOR CHANGES MADE. LOOKS
LIKE FRONT WILL BEGIN TO IMPACT AREA IN THE MORNING BUT STRONGEST
PUSH OF COLD AIR WILL OCCUR JUST AFTER 18Z.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 1148 PM MST WED DEC 18 2013
NORTHWEST FLOW WILL BE THE MAJOR THEME IN THE LONG TERM PERIOD. A
COUPLE OF SHORTWAVE DISTURBANCES WILL MOVE THROUGH AND BRING BRIEF
COOL DOWNS KEEPING TEMPERATURES NEAR CLIMATOLOGICAL NORMALS. THERE
WILL BE SOME WEAK FORCING WITH EACH WAVE...BUT PRECIPITATION
CHANCES APPEAR SLIM TO NONE WITH ONLY LIMITED LOW LEVEL MOISTURE
AVAILABLE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 422 PM MST WED DEC 18 2013
VFR CONDITIONS SHOULD LAST THROUGH THE TAF PERIOD. THE ONLY
QUESTIONABLE TIME PERIOD MAY BE LATE IN THE TAF PERIOD TOWARDS 0Z
TOMORROW FOR KMCK. WINDS WILL BE LIGHT AND VARIABLE THIS EVENING AND
OVERNIGHT WITH INCREASING HIGH CLOUDS. A COLD FRONT WILL MOVE
THROUGH THE TERMINALS EARLY TOMORROW...WITH WINDS SHIFTING TO THE
EAST-NORTHEAST AND INCREASING ABOVE 12 KTS BY MID-LATE MORNING FOR
KMCK AND LATE MORNING FOR KGLD. CEILINGS WILL BEGIN TO DECLINE
BEHIND THE FRONT...STAYING WITHIN VFR CRITERIA AS OF RIGHT NOW.
THE GFS BUFKIT SOUNDING INDICATES LOW CLOUD LAYER DEVELOPING AT
KMCK EARLY TOMORROW AFTERNOON...WITH THE NAM BUFKIT SOUNDING
INDICATING THE LOW CLOUD LAYER AFTER 0Z. THEREFORE...COULD
ANTICIPATE THE POSSIBILITY OF LOWER CEILINGS AT KMCK TOMORROW
SLIGHTLY BEFORE OR AFTER 0Z...BUT KEPT VFR CONDITIONS AS OF RIGHT NOW.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...024
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1152 PM MST WED DEC 18 2013
.UPDATE...
ISSUED AT 748 PM MST WED DEC 18 2013
SEEING A LOT OF VARIABILITY WITH HOURLY TEMPERATURES TONIGHT WITH
A FEW SITES ALREADY DROPPING TO AROUND FREEZING...BUT THEN RISING
AGAIN AS HIGH CLOUDS MOVE OVER. TRIED TO ACCOUNT FOR THIS
VARIABILITY...BUT GIVEN THE DEGREE OF CHANGE GETTING A PERFECT
CURVE WILL BE DIFFICULT. DESPITE THE INITIAL DROP...CURRENT
FORECAST LOOKS ON TRACK WITH ONLY A FEW MINOR CHANGES MADE. LOOKS
LIKE FRONT WILL BEGIN TO IMPACT AREA IN THE MORNING BUT STRONGEST
PUSH OF COLD AIR WILL OCCUR JUST AFTER 18Z.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 234 PM MST WED DEC 18 2013
WESTERLY FLOW WILL CONTINUE THROUGH FRIDAY AHEAD OF A TROUGH MOVING
SOUTHEAST FROM SOUTHERN CALIFORNIA. THE TROUGH WILL MOVE EAST INTO
EASTERN NEW MEXICO SATURDAY. SURFACE HIGH PRESSURE WILL MOVE INTO
THE CENTRAL PLAINS THURSDAY NIGHT AND FRIDAY. A SURFACE TROUGH WILL
MOVE INTO EASTERN COLORADO FRIDAY NIGHT. THIS TROUGH WILL MOVE SOUTH
INTO TEXAS SATURDAY WITH A COLD FRONT FOLLOWING.
THERE WILL BE SOME FLURRIES POSSIBLE THURSDAY NIGHT AS COLDER AIR
FILTERS INTO THE REGION BEHIND THE COLD FRONT. PLAN TO CONTINUE THIS
AREA OF FLURRIES OVER THE NORTHWEST FA WHERE H8-7 LAYER MEAN
MOISTURE IS BEST. OTHERWISE POPS WILL BE NIL THROUGH FRIDAY NIGHT
DUE TO SUBSIDENCE. THE UPPER TROUGH OVER EASTERN NEW MEXICO WILL
BRING A SLIGHT CHANCE OF LIGHT SNOW TO THE FAR SOUTHEAST ZONES
SATURDAY AS DYNAMICS MOVE ACROSS SOUTHWEST AND SOUTH CENTRAL KANSAS.
MIN TEMPERATURES THURSDAY NIGHT WILL FALL INTO THE LOWER TEENS AND
COULD BE COLDER IF SKIES CLEAR. THE COLDEST AIR MOVES AWAY SO THAT
LOW TEMPERATURES FRIDAY NIGHT WILL BE IN THE UPPER TEENS. MAX
TEMPERATURES WILL RANGE FROM 30 TO AROUND 35 FRIDAY AND 35 TO AROUND
40 SATURDAY.
IN THE EXTENDED...(SATURDAY NIGHT THROUGH WEDNESDAY)...
SOME LIGHT SNOW WILL BE POSSIBLE SATURDAY NIGHT AS THE ABOVE
MENTIONED TROUGH MOVES EAST ACROSS THE CENTRAL/SOUTHERN PLAINS.
SLIGHT CHANCE POPS WILL BE OVER THE EXTREME SOUTHEAST FA WHERE
MOISTURE IS BEST. UPPER FLOW WILL BECOME NORTHWEST SUNDAY AND CONTINUE
THROUGH WEDNESDAY. SUBSIDENCE DURING THIS TIME WILL BRING DRY
CONDITIONS.
MIN TEMPERATURES WILL RANGE FROM THE TEENS SATURDAY THROUGH SUNDAY
NIGHTS WARMING TO THE LOWER 20S MONDAY THROUGH WEDNESDAY NIGHTS.
MAX TEMPERATURES SUNDAY WILL BE IN THE LOWER 30S. SOME WARMING INTO
THE 40S WILL OCCUR MONDAY THROUGH WEDNESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1149 PM MST WED DEC 18 2013
VFR CONDITIONS WITH CLOUDY THROUGH THE TAF PERIOD AT MCK AND GLD.
EXPECT WINDS TO INCREASE AND SHIFT TO THE EAST/NORTHEAST FOLLOWING
THE PASSAGE OF A COLD FRONT AT MCK AND THEN GLD AFTER ABOUT 15Z.
EXPECT CEILINGS TO DROP...BUT REMAIN VFR WITH THE ADVANCE OF THE
MUCH COLDER PUSH BETWEEN 01Z-03Z. WINDS WILL ALSO BECOME GUSTY OUT
OF THE NORTH AT THAT TIME.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...FS
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS JACKSON KY
1100 PM EST FRI DEC 20 2013
.UPDATE...
ISSUED AT 1100 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA AS OF 04Z FEATURE SOME SCATTERED
SHOWERS MOVING NORTHEAST FROM TN INTO THE SOUTH CENTRAL AND SOUTHERN
I-75 CORRIDOR OF KENTUCKY. GENERALLY...THE NAM AND HRRR ARE AGREEING
ON ISOLATED TO SCATTERED SHOWERS SKIRTING THE WESTERN EXTEND OF THE
CWA...OR I-75 CORRIDOR THROUGH THE REST OF THE NIGHT. THE BEST LIFT
AND MOISTURE ARRIVES IN THE NORTHWEST IN THE 09Z TO 12Z TIME FRAME AND
IF THERE EVER IS A CHANCE FOR THUNDER TONIGHT...IT WILL OCCUR DURING
THIS PERIOD IN THE PREDAWN HOURS AND KEPT A SLIGHT CHANCE IN THE
FORECAST DUE TO THE LACK OF LIFT AND MOISTURE AT THIS TIME. HAVE
UPDATED AND SENT OUT A FRESH ZFP TO ACCOUNT FOR THIS ADJUSTMENT AND
LOADED CURRENT OBSERVATIONS AND SENT GRIDS TO NDFD.
UPDATE ISSUED AT 830 PM EST FRI DEC 20 2013
AS OF 0130Z SOME SHOWERS ARE BEGINNING TO DEVELOP AND MOVE INTO THE
AREA FROM THE SOUTH AS THE MOISTURE SURGE AND LIFT DEVELOPS AND MOVES
IN FROM THE SOUTHWEST. UPDATED THE GRIDS WITH THE MOST CURRENT OBS
AND HAVE SENT THEM TO NDFD. THE REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 715 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA FEATURE A FEW STRAY SHOWERS
PASSING THROUGH EASTERN KENTUCKY BUT OTHERWISE ANY MEASURABLE PRECIP
LOOKS TO BE NONEXISTENT FOR AT LEAST THE NEXT COUPLE OF HOURS SO AT
THIS POINT...SLIGHT CHANCE SHOWERS LOOK TO BE THE WAY TO GO AND THEN
AS LIFT AND MOISTURE SURGE INCREASES TONIGHT...WILL INTRODUCE SOME
CHANCE AND LIKELY SHOWERS WITH AT LEAST SOME NOTICEABLE ISENTROPIC
LIFT JUST SKIRTING TO THE WEST OF THE I-75 CORRIDOR...WILL LEAVE
SLIGHT CHANCE THUNDERSTORMS JUST IN THE WESTERN ZONES AND ONLY
STARTING IN THE PREDAWN HOURS. HAVE ADJUSTED FOR PRECIP CHANCES
ARRIVING LATER SO A FRESH ZFP HAS BEEN ISSUED FOR THESE SLIGHT
CHANGES. OTHERWISE...HAVE LOADED IN THE LATEST OB AND SENT THE GRIDS
TO NDFD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 359 PM EST FRI DEC 20 2013
ISOLATED TO SCATTERED SHOWERS HAVE BEEN MOVING ACROSS EASTERN
KENTUCKY TODAY. A FRONTAL SYSTEM EXTENDS FROM SOUTHERN MICHIGAN TO
NORTH CENTRAL TEXAS AND HAS MULTIPLE WAVES MOVING ALONG IT. THIS
WILL RESULT IN THE FRONT BOWING TO THE NORTH AHEAD OF THE LOW AND
THEN BOWING DOWN ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE THE
FRONTS TO MOVE PRECIPITATION IN AND OUT OF THE AREA. THE COLD FRONT
WILL FINALLY MOVE THROUGH THE AREA ON SUNDAY WHEN THE UPPER TROUGH
MOVES TO THE WEST AND NORTH OF THE AREA. THE LATEST MODEL RUNS ARE
MOVING THE FRONT THROUGH THE AREA ON SUNDAY MORNING. THERE WILL BE A
STRONG LOW LEVEL JET OUT AHEAD OF THE FRONT. THE JET WILL BE MOVING
INTO THE AREA ON SATURDAY NIGHT. PUT OUT A LAKE WIND ADVISORY TO
COVER THE WIND GUSTS EXPECTED WITH THIS SYSTEM. IT IS POSSIBLE THAT
THIS MAY HAVE TO BE UPGRADED TO A WIND ADVISORY...HOWEVER SINCE IT
WILL BE NIGHT TIME...IT WILL BE HARDER TO MIX THE STRONGER GUSTS DOWN
TO THE SURFACE. THE UPPER ELEVATIONS WOULD BE MOST LIKELY TO SEE THE
STRONGEST GUSTS. THE SEVERE WEATHER THREAT IS ALSO MINIMIZED DUE TO
THE TIME OF DAY THE FRONT WILL BE MOVING THROUGH THE AREA. THE AMOUNT
OF PRECIPITATION EXPECTED WITH THIS SYSTEM IS LIMITED...BECAUSE THE
FRONT WILL BE MOVING FAIRLY QUICKLY THROUGH THE AREA. THE BEST CHANCE
TO SEE THE HEAVY RAIN WILL BE OUT AHEAD OF THE FRONT ON SATURDAY
NIGHT. NEAR RECORD TEMPERATURES ARE EXPECTED TOMORROW.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 409 PM EST FRI DEC 20 2013
THE EXTENDED WILL START OUT WITH A DEEP TROUGH ACROSS THE CENTRAL
CONUS. THIS TROUGH WILL DAMPEN AS IT BECOMES MORE CONSOLIDATED OVER
NEW ENGLAND BY TUESDAY. A SURFACE COLD FRONT WILL CONTINUE ITS SAG
TO THE SOUTHEAST SUNDAY NIGHT...WITH DEEPER MOISTURE EXITING EASTERN
KENTUCKY BY MONDAY MORNING. COLDER AIR WILL BE MOVING IN...WITH
TEMPERATURES LIKELY FALLING THROUGH THE DAY ON MONDAY. THERE
CONTINUES TO BE ENOUGH MOISTURE ADVERTISED FROM MONDAY THROUGH
MONDAY NIGHT TO JUSTIFY SOME SLIGHT CHANCE POPS...LIKELY IN THE FORM
OF FINE RAIN/DRIZZLE OR A BIT OF LIGHT SNOW OR FLURRIES.
DRY AND COLDER WEATHER WILL BE IN PLACE HEADING INTO MID-WEEK...WITH
LOWS DOWN INTO THE TEENS AND 20S TUESDAY AND WEDNESDAY MORNINGS.
ANOTHER TROUGH WILL TAKE AIM AT THE REGION BY THURSDAY...HOWEVER
THE MODEL DISAGREEMENT REMAINS. IN GENERAL...THERE HAS BEEN A DRIER
TREND...SO UNDERCUT THE GIVEN BLENDED MODEL GUIDANCE OUTPUT A BIT
AND KEPT SLIGHT CHANCE POPS IN. TEMPERATURE PROFILES SUPPORT
RAIN/SNOW...HOWEVER LITTLE IF ANY SNOW ACCUMULATION LOOKS TO OCCUR.
ANOTHER REINFORCING SHOT OF DRY AND COLDER HIGH PRESSURE WILL FOLLOW
FOR FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 715 PM EST FRI DEC 20 2013
MVFR CONDITIONS WILL BE ON TAP AS MOISTURE STREAMS UP FROM THE SOUTH
THIS EVENING. THIS WILL CONTINUE THROUGH TONIGHT BEFORE RISING TO VFR
AFTER SUNRISE AND THEN DROPPING TO MVFR AGAIN AS SHOWER ACTIVITY
BECOMES MORE NUMEROUS. WINDS WILL REMAIN QUITE STRONG GUSTING FROM
THE WEST UP TO 20 KNOTS AT TIMES. SOME LOCATIONS WILL RETAIN AN
INVERSION AT TIMES AND WITH WINDS AT 5 KFT AT NEARLY 35 KNOTS SOME
LOCATIONS WILL HAVE SOME WIND SHEAR AT TIMES TONIGHT SO HAVE PUT THAT
IN THE TAFS AS WELL. SURFACE WINDS WILL RAMP UP AGAIN TOMORROW BY 18Z
GUSTING TO 30 KNOTS AT THE SURFACE AT TIMES. SHOWER ACTIVITY WILL
REMAIN SCATTERED MOST OF THE TIME SO WILL LEAVE VICINITY SHOWERS IN
THE TAFS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 7 PM SATURDAY TO 1 PM EST SUNDAY FOR
KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...SHALLENBERGER
SHORT TERM...JJ
LONG TERM...GEOGERIAN
AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS PADUCAH KY
559 PM CST Fri Dec 20 2013
.UPDATE...
ISSUED AT 559 PM CST FRI DEC 20 2013
The AVIATION section has been updated for the 00Z TAF issuance.
&&
.SHORT TERM...(This Evening through Sunday)
ISSUED AT 238 PM CST FRI DEC 20 2013
Flood Watch will continue as is tonight through Saturday night.
Still looking at 2-4+ inches area wide, slightly higher amounts
to 5 inches possible near and just NW of the Ohio River. Front
will enter the area tonight and stall near the Ohio River. Rain
and storms forecast to increase tonight especially after midnight,
continuing through Saturday.
Could see a few strong to severe storms Saturday late day and
evening as wind fields increase substantially with some surface
based instability along and south of the boundary, especially
across west Kentucky. Isolated damaging wind gusts and a brief
short lived tornado or two cannot be ruled out. The activity
should quickly push to the east after midnight Saturday as we
dry slot. Mid level drying will be pronounced, but low level
moisture will linger with SW flow aloft. May be some drizzle into
Sunday but that`s about it, as temperatures fall through the day.
In terms of temps, dew points and winds with the front coming into
the area tonight and Saturday, used a blend of RAP 13km data and
short term 3 hourly GFS/NAM data.
.LONG TERM...(Sunday Night through Friday)
ISSUED AT 238 PM CST FRI DEC 20 2013
In the wake of the weekend storm...colder and drier air will arrive
for early next week. Model soundings depict some lingering moisture
Sunday night until the passage of the 850 mb trough axis. This could
translate into some flurries or drizzle...but no measurable precip
is indicated in the 12z gfs/nam/ecmwf model qpf. By Monday
night...mainly clear skies are expected.
Monday night...the combination of clear skies and decreasing winds
should allow temps to radiate nicely. Will lower Monday night
lows closer to gfs and ecmwf mos...both of which range from 10 to 15
degrees across most of the area.
Tuesday will be another cold day...but there is about a 10 degree
difference between ecmwf and gfs mos highs. The 00z ecmwf is more
progressive with the eastward motion of the thermal trough...while
the 12z gfs lingers the cold air through the day. Will split the
difference between them...which yields highs in the upper 20s to
lower 30s despite sunny skies.
The models depict a 500 mb longwave trough axis setting up over the
Mississippi Valley Christmas Day into Thursday. Shortwaves rotating
through the trough will bring at least some cloudiness...if not
measurable light precip. Model soundings have trended drier during
this time period...and the 12z gfs and gfs ensemble mean show zero
qpf. The 12z ecmwf indicates some patchy light precip. Will follow
the model trends and lower pops into the slight chance category for
Christmas night and Thursday. Precip type would be mainly snow until
boundary layer temps become marginal for snow Thursday
afternoon.
In the wake of the departing longwave trough...another shot of cold
air is expected for Friday. As would be expected seven days
out...there is fair to poor agreement on how cold it will get.
Forecast will represent a blend of gfs/ecmwf temps.
&&
.AVIATION...
ISSUED AT 559 PM CST FRI DEC 20 2013
Made a few modifications to the existing TAFs. MVFR ceilings are
bouncing in and out across the area early this evening, so threw
in a TEMPO to handle that situation.
The front is just now entering the area and will pass KCGI this
evening. It will settle over KPAH and KEVV late tonight and become
stationary well into Saturday morning. Current thinking is that it
will stay southeast of KCGI and not pass KOWB through the end of this
TAF period. Added a couple of groups to handle the cha cha cha
expected at KPAH and KEVV late tonight through late Saturday
morning. Could see some strong south winds with gusts over 20kts
Saturday afternoon, except at KCGI.
Continued with the showers and VCTS through the day Saturday, with
gradually lowering ceilings through the period. IFR or lower
conditions are expected for much of the day.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH through late Saturday night FOR ILZ075>078-080>094.
MO...FLOOD WATCH through late Saturday night FOR MOZ076-086-087-100-
107>112-114.
IN...FLOOD WATCH through late Saturday night FOR INZ081-082-085>088.
KY...FLOOD WATCH through late Saturday night FOR KYZ001>022.
&&
$$
UPDATE...DRS
AVIATION...DRS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1148 PM CST Wed Dec 18 2013
.UPDATE...
ISSUED AT 942 PM CST WED DEC 18 2013
South winds, just off the surface, are increasing over the
region this evening. KVWX VAD Wind profile indicates 45kts at
925mb and 50kts at 850mb as 0318Z. Cannot see surface winds
decreasing substantially overnight, so we may not see much fall
in temperatures. Just updated to increase lows and winds in some
locations. Leaned on the LAMP and RUC data for the update.
The dewpoints have also been fun to account for, with drier than
expected air over the southern Pennyrile, and increasing moisture
in SEMO. The HRRR seems to have the best handle on the dry air,
but it is likely too aggressive in moistening the southwest. Tried
to just blend it in with the existing forecast to at least head in
the right direction with the trends.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 152 PM CST WED DEC 18 2013
Southerly winds will keep temperatures up above freezing for most
locations overnight for the first time in a long time. Even though
we will have nearly the lowest sun angle of the year...the snow
field retreats and southerly winds combine to push temps to near 60
across southern portions of the heartland Thursday. High pressure
will gradually be forced off the southeast coast as the upper level
trough digs southeast before ejecting northeast into the heartland.
Otherwise very few changes to the short term.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 152 PM CST WED DEC 18 20131
Will be warm sector Thursday night and most of Friday. Scattered
shower activity expected as the atmosphere moistens up and
impulses move SW/NE across the area. Not much organization wise
given no boundaries to focus on. Mainly mid level support and WAA.
Best chance of thunder Friday should be across the SRN 1/3 of the
area. Late Friday afternoon a strong cold front will enter into
our NW CWFA. The front is forecast to push southeast into our area
and then stall. Showers/TSRA should increase after midnight Friday
night with convective focus near and just north of the boundary.
The boundary should stall somewhere near the Ohio River. The front
will then lift back north as a warm front Saturday as the upper
flow backs and surface low pressure forms along the front, ending
up over west AR by 00z Sun ahead of a strong H5 moving east along
the US/Mexico border into the srn Plains. The convection/locally heavy
rains should pick up Saturday. The axis may shift slowly northwest
with time, in line with the movement of the front.
Saturday night, the front should park across se MO into srn IL
with areas south into west KY (including sw IN) warm sector. Again
with respect to greatest QPF we are leaning away from the GFS as
the axis seems too far east into the warm sector, whereas the
ECMWF focuses the best QPF more in line with strong 700mb
transport and 850mb speed convergence, which is more to the west
and closer to the surface boundary. WPC continues to lean toward this
solution as well. Having said that, would not be surprised to see
an adjustment back to the east just a tad, but not as far as the
GFS. All said and done, main focus Friday night through early
Sunday, 1 1/2-3" rain amounts west KY, increasing to 3-4" or so
from about the Ohio River on north and west. Higher amounts
possible. Will continue with our Hydrologic Outlook product, to
detail the prospects of flooding. As we`ve stated since Monday,
precipitable water values are forecast to remain very high,
1.5-1.75". The potential precip efficiency is cause for concern
given the saturated ground conditions. Concern is mainly small
creeks, ditches, roads that typically flood. Could be a lot of
standing water in fields, etc.
Confidence continues to increase there may be severe storms,
primarily Saturday night, and especially SE of a Poplar Bluff
Missouri, to Evansville Indiana line. This is when we see a notable
increase in forecast winds, from 65-70kts around 850mb up to 85-95
kts 700-500mb, and veering. This coupled with a period of surface
based instability Saturday night in the warm sector, means we could
see some quasi linear segments form and possibly produce damaging
wind gusts and perhaps the typical brief spin up tornado or two we
typically see with a QLCS setup.
Front will blast through Sunday, with precip chances lowering
rapidly from west to east. Temperatures will fall through the day.
Sunday night, mainly dry, though cannot rule out entirely very
light snow or flurries until the mid level wave passes to our
east.
Monday through Christmas day will be dry and seasonably chilly as
strong high pressure builds across the region.
&&
.AVIATION...
ISSUED AT 1148 PM CST WED DEC 18 2013
A change was made for the last six (6) hour of the TAF forecast.
The addition of showers and MVFR ceilings at KCGI/KPAH with the
approaching weather system.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...DRS
SHORT TERM...KH
LONG TERM...CN
AVIATION...Smith
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1240 PM EST THU DEC 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 452 AM EST THU DEC 19 2013
A 1005MB LOW PRESSURE OVER EASTERN LAKE SUPERIOR CONTINUES TO
QUICKLY SLIDE EAST THIS MORNING...AS AN ASSOCIATED 925/850MB TROUGH
EXITS THE UPPER GREAT LAKES REGION. THIS QUICK DEPARTURE HAS LED TO
WINDS TURNING TO THE NORTHWEST OVER THE WESTERN LAKE AND AN AREA OF
MVFR CLOUDS (PICKED UP WELL IN THE RH FIELDS OF THE RAP ANALYSIS)
DROPPING SOUTHEAST ACROSS WESTERN AND NORTH CENTRAL UPPER MICHIGAN.
CEILINGS HAVE BEEN LOWERING FAIRLY STEADILY AT KCMX OVER THE LAST
COUPLE OF HOURS AND WITH THE RAP INDICATING 925MB TEMPS FALLING TO
-10C OVER WESTERN LAKE SUPERIOR...HAVE BEEN SEEING INDICATIONS ON
SATELLITE THAT LAKE EFFECT CLOUDS HAVE BEEN DEVELOPING. HAVEN/T
SEEN ANY PRECIPITATION NOTED AT CMX OR ON WEBCAMS OVER THE
KEWEENAW...BUT WOULD EXPECT LIGHT SNOW OR FREEZING DRIZZLE TO START
SHORTLY.
FOR TODAY...WITH THE LOW SLIDING EAST EARLY THIS MORNING AND THE
MAIN SHORTWAVE TO THE NORTHWEST OF LAKE SUPERIOR JUST BRUSHING THE
NORTHERN PART OF THE LAKE...THERE APPEARS TO BE LITTLE SYNOPTIC
FORCING ACROSS THE AREA FOR MUCH OF THE DAY. OTHER THAN THE
POTENTIAL FOR A BRIEF STRONGER SHOWERS MOVING ACROSS EASTERN LAKE
SUPERIOR WITH THE FRONT AND WIND SHIFT TO THE NORTHWEST.
OTHERWISE...THE COLDER AIR DROPPING SOUTHEAST ACROSS LAKE SUPERIOR
(925MB TEMPS FALLING TO -13C BY 00Z FRIDAY) WILL LEAD TO AN INCREASE
IN LIGHT LAKE EFFECT PRECIPITATION THIS MORNING. WITH A HIGH
PRESSURE RIDGE LOCATED JUST TO THE NORTH OF LAKE SUPERIOR TODAY
WILL LEAD TO WINDS VEERING TO THE NORTH-NORTHEAST THROUGH THE DAY.
THIS ANTI-CYCLONIC FLOW ACROSS THE LAKE WON/T BE TOO FAVORABLE FOR
LAKE EFFECT...WHICH WILL COMBINE WITH THE STRONG POCKET OF DRY
AIR ABOVE 850MB (INVERSION HEIGHTS AROUND 4KFT) ASSOCIATED WITH THE
HIGH TO KEEP ANY PRECIPITATION LIGHT. THERE IS SOME CONCERN ON SOME
FREEZING DRIZZLE MIXING WITH THE SNOW FOR THE FIRST PART OF THE
MORNING NEAR LAKE SUPERIOR AND HAVE TRIED TO FOLLOW THE TIMING OF
THE 925MB AROUND -9/-10C TO MARK THE TRANSITION TO ALL SNOW THIS
MORNING. AS FOR AMOUNTS...THINK A DUSTING TO AN INCH SEEMS
REASONABLE...WITH THE MOST IN THE FAVORED NORTH-NORTHEAST UPSLOPE
LOCATIONS OF NORTH CENTRAL UPPER MICHIGAN.
FOR TONIGHT...A QUICK MOVING DISTURBANCE WILL MOVE ACROSS UPPER
MICHIGAN IN THE WESTERLY FLOW ALOFT. IN ADDITIONS TO THE
SHORTWAVE...THE UPPER GREAT LAKES REGION WILL BE UNDER THE
FAVORABLE RIGHT REAR OF A 160KT UPPER JET AND PROVIDE DECENT
SUPPORT ALOFT FOR A SWATH OF SNOW TO MOVE ACROSS THE CWA. AT THE
SURFACE...A WEAK INVERTED TROUGH DOES LOOK TO DEVELOP OVER CENTRAL
UPPER MICHIGAN...WITH WILL HELP KEEP THE LOW LEVEL (950-900MB) FLOW
FOCUSED OVER NORTH CENTRAL UPPER MICHIGAN TO PROVIDE LAKE
ENHANCEMENT. MODELS HAVE BEEN FAIRLY CONSISTENT ON THE SWATH OF
SNOW/QPF MOVING EAST ACROSS THE CWA AROUND MID EVENING AND THEN
QUICKLY DEPARTION ABOUT HALFWAY THROUGH THE OVERNIGHT HOURS.
A GENERAL CONSENSUS IS FOR 0.1-0.15IN OF QPF MOVING ACROSS
CENTRAL/SOUTHERN UPPER MICHIGAN TONIGHT (ONLY 0.05-0.10 OVER THE
KEWEENAW) AND HAVE FOLLOWED THAT FOR THE SYNOPTIC QPF. ONE ITEM TO
NOTE IS THAT THAT DRY POCKET OF AIR BETWEEN 850-700MB WILL NEED TO
BE OVERCOME BEFORE THE SNOW CAN START. FORTUNATELY...THE FLOW IN
THAT LAYER IS FAIRLY LIGHT AND SHOULD ALLOW IT TO QUICKLY MOISTEN.
THEN...WITH THAT FAVORABLE NORTHEAST UPSLOPE AND LAKE ENHANCED
FLOW...ADJUSTED VALUES UP OVER THE HIGHER TERRAIN OF THE NORTH
CENTRAL U.P. FROM THE HURON MOUNTAINS THROUGH NEGAUNEE/GWINN. THE
TRICKY PART IN THE FORECAST COMES FROM PINNING DOWN SNOW RATIOS.
WITH MUCH OF THE BROAD MID LEVEL FGEN FOCUSED WITHIN THE
DGZ...WOULD EXPECT THERE TO BE A 3-4HR PERIOD OF SNOW RATIOS AROUND
20-1 BEFORE A DOWNWARD TREND ONCE THE BETTER FORCING DEPARTS. COBB
OUTPUT AWAY FROM THE LAKE ENHANCEMENT SUPPORTS THAT IDEA AND WITH
THAT DGZ LAYER BEING FAIRLY ISOTHERMAL...HAVE CONTINUED THOSE
RATIOS IN THE FORECAST. IN THE LAKE ENHANCEMENT AREA...THERE ARE
HINTS OF BETTER FORCING BELOW THE DGZ THAT COULD LEAD TO SLIGHTLY
LOWER RATIOS...BUT WONDERING IF THAT MAY BE A TOUCH TOO LOW AS IT
BEING ABOUT 1KFT HIGHER IT WOULD BE IN THE DGZ. THUS...OPTED TO
KEEP THE HIGHER RATIOS IN THE LAKE/TERRAIN ENHANCED AREAS TOO. THIS
LEADS TO A WIDESPREAD 1-3 INCH SNOWFALL FOR MUCH OF UPPER
MICHIGAN...WITH SOME LOCALLY HIGHER AMOUNTS IN THE NORTH CENTRAL.
DEBATED AN ADVISORY FOR MARQUETTE COUNTY FOR AN AVERAGE MORE LIKE
2-4INCHES...BUT OPTED TO DO AN SPS FOR THE ENTIRE CWA INSTEAD.
THERE WERE 2 MAIN REASONS FOR NOT GOING WITH AN ADVISORY.
ONE...SINCE THE MAIN SNOW WILL LIKELY FALL BETWEEN 10PM AND
3AM...THE IMPACTS ON THE POPULATION WILL BE LOWER AND THERE SHOULD
STILL BE ENOUGH TIME TO TREAT THE ROADS BEFORE THE MORNING COMMUTE.
THE SECOND IS A COMBINATION ON UNCERTAINTY WITH SNOW RATIOS AND QPF
AMOUNTS...WHICH BEING OFF BY A COUPLE HUNDREDTHS AT 20 TO 1 COULD
QUICKLY LOWER AMOUNTS. GOING FORECAST WAS FAIRLY SIMILAR TO THE 00Z
NAM AND LOCAL WRF-ARW RUNS...BUT THE 06Z NAM THAT JUST ARRIVED HAS
DROPPED QPF AMOUNTS IN THE ENHANCED AREAS BY 0.07IN. THUS...FELT
HOLDING OFF ON A BORDERLINE ADVISORY WAS WARRANTED AND WILL PASS
CONCERNS TO DAYSHIFT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 452 AM EST THU DEC 19 2013
ANY REMAINING MOISTURE AND LIFT RAPIDLY MOVES SOUTH AND EAST ON
FRIDAY MORNING AS A WEAK RIDGE AXIS BUILDS ACROSS LAKE SUPERIOR.
THIS SHOULD ALLOW ANY SNOW SHOWERS OFF THE LAKE TO END QUICKLY IN
THE MORNING. THERE IS A HINT OF LINGERING DEEP MOISTURE ACROSS FAR
SOUTHERN UPPER MI FRI IN THE DEFORMATION ZONE...WITH THE NAM AND
ECMWF SHOWING WEAK MID-LEVEL Q-VECTOR CONVERGENCE THROUGH THE DAY.
HOWEVER...WITH LACK OF SIGNIFICANT LOW LEVEL LIFT AND FAIRLY STRONG
CONFLUENCE ALOFT...WILL LIMIT ANY POPS TO JUST SLIGHT CHANCE ON
FRIDAY ACROSS THE FAR SOUTH.
ON FRIDAY NIGHT INTO SATURDAY...ANOTHER WEAK UPPER TROUGH ROTATES
THROUGH THE AREA. WITH REMAINING MOISTURE ACROSS THE FAR SOUTH FRI
NIGHT...WILL MAINTAIN LOW CHANCE POPS MAINLY IN MENOMINEE COUNTY BUT
AGAIN THE LIFT IS MINIMAL AT BEST. THE NAM SEEMS TO BE AN OUTLIER IN
DEVELOPING A WEAK AREA OF LOW PRESSURE ALONG THE FRONT OVER LAKE
SUPERIOR AND KEEPING IT NEARLY STATIONARY THROUGH SATURDAY BEFORE
MERGING WITH THE DEVELOPING LOW OVER THE SOUTHERN PLAINS SATURDAY
NIGHT. IN FACT...THE NAM ACTUALLY SHOWS ON LAKE MICHIGAN LAKE EFFECT
DEVELOPING IN SCHOOLCRAFT AND DELTA COUNTIES SATURDAY DUE TO THE
SOUTHERLY FLOW AHEAD OF THE LOW. MEANWHILE...THE ECMWF AND THE GFS
SUGGEST A WEAK OPEN WAVE AT BEST WITH MUCH LESS MOISTURE AND LITTLE
IF ANY QPF ON SATURDAY. GIVEN THE WEAK DYNAMICS AT BEST AND THAT THE
NAM IS THE OUTLIER...WILL GENERALLY FOLLOW THE ECMWF SOLUTION AND
KEEP LIMIT ANY POPS TO SLIGHT CHANCE FOR SATURDAY.
FOR THE SOUTHERN STREAM SYSTEM SAT NIGHT INTO SUNDAY NIGHT MOVING
THROUGH THE SOUTHERN GREAT LAKES...THE 18/12Z RUNS STARTED TO TREND
NORTH AND WEST WITH THE LOW. THE 19/00Z RUNS HAVE GENERALLY
CONTINUED THIS TREND WITH THE 19/00Z ECMWF SHIFTING EVEN FURTHER
NORTH AND WEST. WITH THE SYSTEM CLOSING OFF OVER THE SOUTHWESTERN
STATES...WOULD EXPECT THAT THE SYSTEM OVERALL WILL EJECT OUT INTO
THE PLAINS A LITTLE SLOWER THAN THE MODELS SUGGEST. THIS WOULD ALLOW
THE NORTHERN STREAM ENERGY TO POTENTIALLY PHASE WITH THE SOUTHERN
STREAM ENERGY FURTHER NORTH AND WEST...CAUSING THE LOW TO ALSO TRACK
A LITTLE FURTHER NORTH/WEST. AS SUCH...HAVE OPTED TO BRING LIKELY
POPS ACROSS THE ENTIRE EAST HALF OF UPPER MICHIGAN ON SUNDAY/SUNDAY
NIGHT AND RAISE POPS TO NEAR CATEGORICAL IN NORTH CENTRAL UPPER MI.
THIS TYPE OF TRACK WOULD ALLOW FOR A SETUP FOR DECENT LAKE
ENHANCEMENT IN THOSE AREAS FAVORED BY NORTHERLY WINDS WITH PLENTY
OFF DEEP MOISTURE AND AT LEAST SOME SYNOPTIC LIFT IN THE DEFORMATION
ZONE. DO NOT WANT TO TOTALLY BUY OFF ON THE LATEST ECMWF YET AS IT
IS STILL BY FAR THE FURTHEST N AND W...BUT THERE CERTAINLY EXISTS A
POSSIBILITY OF PLOWABLE SNOWFALL FOR MUCH OF THE EASTERN HALF /OR
PERHAPS THE ENTIRE CWFA/ SUNDAY...AND PERHAPS A SIGNIFICANT SNOW FOR
THE FAVORABLE LAKE ENHANCED AREAS. BOTTOM LINE THOUGH...THERE IS
STILL A GREAT AMOUNT OF UNCERTAINTY SO STAY TUNED...
OTHERWISE...BEHIND THIS SYSTEM THE WEATHER QUIETS DOWN WITH A BROAD
LONG WAVE TROUGH SETTLING ACROSS NORTH AMERICA. EXPECT SOME LAKE
EFFECT MONDAY AS THE MAIN SHORT WAVE TROUGH PASSES THROUGH WITH
LINGERING MOISTURE AND 850MB TEMPS AROUND -20C. HOWEVER...THE SFC
RIDGE QUICKLY BUILDS IN BY TUE MORNING WHICH SHOULD END ANY LES.
COULD BE QUITE A COLD MORNING ON CHRISTMAS EVE MORNING WITH THE
RIDGE OVERHEAD AND CLEARING SKIES. WILL GO WITH TEMPS WELL BELOW
ZERO FOR MOST INTERIOR LOCATIONS. MAY BE ONE OF THOSE -20F MORNINGS
IN THE NORMALLY COLDER SPOTS IF IT STAYS CLEAR AND CALM. SOME LIGHT
SNOW IS POSSIBLE LATER ON CHRISTMAS EVE INTO CHRISTMAS DAY AS THE
FRONTAL SYSTEM MOVES INTO THE AREA ASSOCIATED WITH A FAIRLY POTENT
LOOKING SHORT WAVE TROUGH...BUT DETAILS ARE TOUGH TO PIN DOWN. TEMPS
IN THE EXTENDED STILL LOOK BELOW NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1238 PM EST THU DEC 19 2013
HAVE LIMITED IMPROVEMENT THIS AFTERNOON AND EVENING AS LAKE EFFECT
SNOW IS STRONGER AND MORE PERSISTENT THAN PREVIOUSLY EXPECTED. DO
HAVE CONDITIONS SLOWLY IMPROVING INTO THIS EVENING AS HIGH PRESSURE
WILL BE LESS FAVORABLE FOR LAKE EFFECT SNOW.
A DISTURBANCE SLIDING ACROSS UPPER MICHIGAN TONIGHT WILL LEAD TO A
3-5HR BURST OF SNOW AT ALL TAF SITES. THINK KIWD/KSAW WILL SEE THE
WORST CONDITIONS. EXPECT IMPROVEMENT IN THE OVERNIGHT HOURS FROM
WEST TO EAST...ALTHOUGH ALL SITES WILL STILL SEE LIGHT SNOW SHOWERS
AND MVFR CONDITIONS. SNOW SHOWERS WILL CONTINUE INTO EARLY FRIDAY
AFTERNOON AS COLDER AIR AND LINGERING LOW LEVEL MOISTURE LEADS TO
LAKE EFFECT AT ALL SITES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 452 AM EST THU DEC 19 2013
A LOW DEPARTING EASTERN LAKE SUPERIOR THIS MORNING HAS LED TO AN
INCREASE IN NORTHWEST TO NORTHERLY WINDS ACROSS WESTERN LAKE
SUPERIOR EARLY THIS MORNING AND IT SHOULD SPREAD EAST ACROSS THE
REST OF THE LAKE THROUGH THE MORNING HOURS. ALTHOUGH THERE MAY BE A
FEW GUSTS TO THE 30KT RANGE THIS MORNING...WOULD EXPECT THEM TO
MAINLY BE AROUND 25KTS. A HIGH PRESSURE RIDGE BUILDING OVER
SOUTHERN ONTARIO THIS AFTERNOON WILL WEAKEN THE WINDS THROUGH THE
AFTERNOON AND NIGHT (TO BELOW 20KTS) AS A WEAK LOW TRACKS THROUGH
SOUTHERN LOWER MICHIGAN. THIS HIGH PRESSURE RIDGE WILL CROSS THE
UPPER GREAT LAKES ON FRIDAY AND FRIDAY NIGHT AND LEAD TO CONTINUED
WINDS BELOW 20KTS THROUGH THE FIRST HALF OF THE WEEKEND. A STRONGER
LOW EXITING THE SOUTHERN PLAINS ON SATURDAY AFTERNOON WILL MOVE
THROUGH SOUTHEAST LOWER MICHIGAN ON SUNDAY AND WILL INCREASE
NORTHERLY WINDS ACROSS THE LAKE. AT THIS TIME...EXPECT WINDS TO BE
AROUND 30KTS WITH A FEW GALE FORCE GUSTS TO 35KTS BEFORE DIMINISHING
SUNDAY NIGHT INTO MONDAY.
FINALLY...FREEZING SPRAY WILL BE POSSIBLE DURING THE TIMES OF
STRONGER WINDS...LARGELY TODAY AND LATE SATURDAY NIGHT INTO SUNDAY
NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...MRD
AVIATION...TITUS
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
641 AM EST THU DEC 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 452 AM EST THU DEC 19 2013
A 1005MB LOW PRESSURE OVER EASTERN LAKE SUPERIOR CONTINUES TO
QUICKLY SLIDE EAST THIS MORNING...AS AN ASSOCIATED 925/850MB TROUGH
EXITS THE UPPER GREAT LAKES REGION. THIS QUICK DEPARTURE HAS LED TO
WINDS TURNING TO THE NORTHWEST OVER THE WESTERN LAKE AND AN AREA OF
MVFR CLOUDS (PICKED UP WELL IN THE RH FIELDS OF THE RAP ANALYSIS)
DROPPING SOUTHEAST ACROSS WESTERN AND NORTH CENTRAL UPPER MICHIGAN.
CEILINGS HAVE BEEN LOWERING FAIRLY STEADILY AT KCMX OVER THE LAST
COUPLE OF HOURS AND WITH THE RAP INDICATING 925MB TEMPS FALLING TO
-10C OVER WESTERN LAKE SUPERIOR...HAVE BEEN SEEING INDICATIONS ON
SATELLITE THAT LAKE EFFECT CLOUDS HAVE BEEN DEVELOPING. HAVEN/T
SEEN ANY PRECIPITATION NOTED AT CMX OR ON WEBCAMS OVER THE
KEWEENAW...BUT WOULD EXPECT LIGHT SNOW OR FREEZING DRIZZLE TO START
SHORTLY.
FOR TODAY...WITH THE LOW SLIDING EAST EARLY THIS MORNING AND THE
MAIN SHORTWAVE TO THE NORTHWEST OF LAKE SUPERIOR JUST BRUSHING THE
NORTHERN PART OF THE LAKE...THERE APPEARS TO BE LITTLE SYNOPTIC
FORCING ACROSS THE AREA FOR MUCH OF THE DAY. OTHER THAN THE
POTENTIAL FOR A BRIEF STRONGER SHOWERS MOVING ACROSS EASTERN LAKE
SUPERIOR WITH THE FRONT AND WIND SHIFT TO THE NORTHWEST.
OTHERWISE...THE COLDER AIR DROPPING SOUTHEAST ACROSS LAKE SUPERIOR
(925MB TEMPS FALLING TO -13C BY 00Z FRIDAY) WILL LEAD TO AN INCREASE
IN LIGHT LAKE EFFECT PRECIPITATION THIS MORNING. WITH A HIGH
PRESSURE RIDGE LOCATED JUST TO THE NORTH OF LAKE SUPERIOR TODAY
WILL LEAD TO WINDS VEERING TO THE NORTH-NORTHEAST THROUGH THE DAY.
THIS ANTI-CYCLONIC FLOW ACROSS THE LAKE WON/T BE TOO FAVORABLE FOR
LAKE EFFECT...WHICH WILL COMBINE WITH THE STRONG POCKET OF DRY
AIR ABOVE 850MB (INVERSION HEIGHTS AROUND 4KFT) ASSOCIATED WITH THE
HIGH TO KEEP ANY PRECIPITATION LIGHT. THERE IS SOME CONCERN ON SOME
FREEZING DRIZZLE MIXING WITH THE SNOW FOR THE FIRST PART OF THE
MORNING NEAR LAKE SUPERIOR AND HAVE TRIED TO FOLLOW THE TIMING OF
THE 925MB AROUND -9/-10C TO MARK THE TRANSITION TO ALL SNOW THIS
MORNING. AS FOR AMOUNTS...THINK A DUSTING TO AN INCH SEEMS
REASONABLE...WITH THE MOST IN THE FAVORED NORTH-NORTHEAST UPSLOPE
LOCATIONS OF NORTH CENTRAL UPPER MICHIGAN.
FOR TONIGHT...A QUICK MOVING DISTURBANCE WILL MOVE ACROSS UPPER
MICHIGAN IN THE WESTERLY FLOW ALOFT. IN ADDITIONS TO THE
SHORTWAVE...THE UPPER GREAT LAKES REGION WILL BE UNDER THE
FAVORABLE RIGHT REAR OF A 160KT UPPER JET AND PROVIDE DECENT
SUPPORT ALOFT FOR A SWATH OF SNOW TO MOVE ACROSS THE CWA. AT THE
SURFACE...A WEAK INVERTED TROUGH DOES LOOK TO DEVELOP OVER CENTRAL
UPPER MICHIGAN...WITH WILL HELP KEEP THE LOW LEVEL (950-900MB) FLOW
FOCUSED OVER NORTH CENTRAL UPPER MICHIGAN TO PROVIDE LAKE
ENHANCEMENT. MODELS HAVE BEEN FAIRLY CONSISTENT ON THE SWATH OF
SNOW/QPF MOVING EAST ACROSS THE CWA AROUND MID EVENING AND THEN
QUICKLY DEPARTION ABOUT HALFWAY THROUGH THE OVERNIGHT HOURS.
A GENERAL CONSENSUS IS FOR 0.1-0.15IN OF QPF MOVING ACROSS
CENTRAL/SOUTHERN UPPER MICHIGAN TONIGHT (ONLY 0.05-0.10 OVER THE
KEWEENAW) AND HAVE FOLLOWED THAT FOR THE SYNOPTIC QPF. ONE ITEM TO
NOTE IS THAT THAT DRY POCKET OF AIR BETWEEN 850-700MB WILL NEED TO
BE OVERCOME BEFORE THE SNOW CAN START. FORTUNATELY...THE FLOW IN
THAT LAYER IS FAIRLY LIGHT AND SHOULD ALLOW IT TO QUICKLY MOISTEN.
THEN...WITH THAT FAVORABLE NORTHEAST UPSLOPE AND LAKE ENHANCED
FLOW...ADJUSTED VALUES UP OVER THE HIGHER TERRAIN OF THE NORTH
CENTRAL U.P. FROM THE HURON MOUNTAINS THROUGH NEGAUNEE/GWINN. THE
TRICKY PART IN THE FORECAST COMES FROM PINNING DOWN SNOW RATIOS.
WITH MUCH OF THE BROAD MID LEVEL FGEN FOCUSED WITHIN THE
DGZ...WOULD EXPECT THERE TO BE A 3-4HR PERIOD OF SNOW RATIOS AROUND
20-1 BEFORE A DOWNWARD TREND ONCE THE BETTER FORCING DEPARTS. COBB
OUTPUT AWAY FROM THE LAKE ENHANCEMENT SUPPORTS THAT IDEA AND WITH
THAT DGZ LAYER BEING FAIRLY ISOTHERMAL...HAVE CONTINUED THOSE
RATIOS IN THE FORECAST. IN THE LAKE ENHANCEMENT AREA...THERE ARE
HINTS OF BETTER FORCING BELOW THE DGZ THAT COULD LEAD TO SLIGHTLY
LOWER RATIOS...BUT WONDERING IF THAT MAY BE A TOUCH TOO LOW AS IT
BEING ABOUT 1KFT HIGHER IT WOULD BE IN THE DGZ. THUS...OPTED TO
KEEP THE HIGHER RATIOS IN THE LAKE/TERRAIN ENHANCED AREAS TOO. THIS
LEADS TO A WIDESPREAD 1-3 INCH SNOWFALL FOR MUCH OF UPPER
MICHIGAN...WITH SOME LOCALLY HIGHER AMOUNTS IN THE NORTH CENTRAL.
DEBATED AN ADVISORY FOR MARQUETTE COUNTY FOR AN AVERAGE MORE LIKE
2-4INCHES...BUT OPTED TO DO AN SPS FOR THE ENTIRE CWA INSTEAD.
THERE WERE 2 MAIN REASONS FOR NOT GOING WITH AN ADVISORY.
ONE...SINCE THE MAIN SNOW WILL LIKELY FALL BETWEEN 10PM AND
3AM...THE IMPACTS ON THE POPULATION WILL BE LOWER AND THERE SHOULD
STILL BE ENOUGH TIME TO TREAT THE ROADS BEFORE THE MORNING COMMUTE.
THE SECOND IS A COMBINATION ON UNCERTAINTY WITH SNOW RATIOS AND QPF
AMOUNTS...WHICH BEING OFF BY A COUPLE HUNDREDTHS AT 20 TO 1 COULD
QUICKLY LOWER AMOUNTS. GOING FORECAST WAS FAIRLY SIMILAR TO THE 00Z
NAM AND LOCAL WRF-ARW RUNS...BUT THE 06Z NAM THAT JUST ARRIVED HAS
DROPPED QPF AMOUNTS IN THE ENHANCED AREAS BY 0.07IN. THUS...FELT
HOLDING OFF ON A BORDERLINE ADVISORY WAS WARRANTED AND WILL PASS
CONCERNS TO DAYSHIFT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 452 AM EST THU DEC 19 2013
ANY REMAINING MOISTURE AND LIFT RAPIDLY MOVES SOUTH AND EAST ON
FRIDAY MORNING AS A WEAK RIDGE AXIS BUILDS ACROSS LAKE SUPERIOR.
THIS SHOULD ALLOW ANY SNOW SHOWERS OFF THE LAKE TO END QUICKLY IN
THE MORNING. THERE IS A HINT OF LINGERING DEEP MOISTURE ACROSS FAR
SOUTHERN UPPER MI FRI IN THE DEFORMATION ZONE...WITH THE NAM AND
ECMWF SHOWING WEAK MID-LEVEL Q-VECTOR CONVERGENCE THROUGH THE DAY.
HOWEVER...WITH LACK OF SIGNIFICANT LOW LEVEL LIFT AND FAIRLY STRONG
CONFLUENCE ALOFT...WILL LIMIT ANY POPS TO JUST SLIGHT CHANCE ON
FRIDAY ACROSS THE FAR SOUTH.
ON FRIDAY NIGHT INTO SATURDAY...ANOTHER WEAK UPPER TROUGH ROTATES
THROUGH THE AREA. WITH REMAINING MOISTURE ACROSS THE FAR SOUTH FRI
NIGHT...WILL MAINTAIN LOW CHANCE POPS MAINLY IN MENOMINEE COUNTY BUT
AGAIN THE LIFT IS MINIMAL AT BEST. THE NAM SEEMS TO BE AN OUTLIER IN
DEVELOPING A WEAK AREA OF LOW PRESSURE ALONG THE FRONT OVER LAKE
SUPERIOR AND KEEPING IT NEARLY STATIONARY THROUGH SATURDAY BEFORE
MERGING WITH THE DEVELOPING LOW OVER THE SOUTHERN PLAINS SATURDAY
NIGHT. IN FACT...THE NAM ACTUALLY SHOWS ON LAKE MICHIGAN LAKE EFFECT
DEVELOPING IN SCHOOLCRAFT AND DELTA COUNTIES SATURDAY DUE TO THE
SOUTHERLY FLOW AHEAD OF THE LOW. MEANWHILE...THE ECMWF AND THE GFS
SUGGEST A WEAK OPEN WAVE AT BEST WITH MUCH LESS MOISTURE AND LITTLE
IF ANY QPF ON SATURDAY. GIVEN THE WEAK DYNAMICS AT BEST AND THAT THE
NAM IS THE OUTLIER...WILL GENERALLY FOLLOW THE ECMWF SOLUTION AND
KEEP LIMIT ANY POPS TO SLIGHT CHANCE FOR SATURDAY.
FOR THE SOUTHERN STREAM SYSTEM SAT NIGHT INTO SUNDAY NIGHT MOVING
THROUGH THE SOUTHERN GREAT LAKES...THE 18/12Z RUNS STARTED TO TREND
NORTH AND WEST WITH THE LOW. THE 19/00Z RUNS HAVE GENERALLY
CONTINUED THIS TREND WITH THE 19/00Z ECMWF SHIFTING EVEN FURTHER
NORTH AND WEST. WITH THE SYSTEM CLOSING OFF OVER THE SOUTHWESTERN
STATES...WOULD EXPECT THAT THE SYSTEM OVERALL WILL EJECT OUT INTO
THE PLAINS A LITTLE SLOWER THAN THE MODELS SUGGEST. THIS WOULD ALLOW
THE NORTHERN STREAM ENERGY TO POTENTIALLY PHASE WITH THE SOUTHERN
STREAM ENERGY FURTHER NORTH AND WEST...CAUSING THE LOW TO ALSO TRACK
A LITTLE FURTHER NORTH/WEST. AS SUCH...HAVE OPTED TO BRING LIKELY
POPS ACROSS THE ENTIRE EAST HALF OF UPPER MICHIGAN ON SUNDAY/SUNDAY
NIGHT AND RAISE POPS TO NEAR CATEGORICAL IN NORTH CENTRAL UPPER MI.
THIS TYPE OF TRACK WOULD ALLOW FOR A SETUP FOR DECENT LAKE
ENHANCEMENT IN THOSE AREAS FAVORED BY NORTHERLY WINDS WITH PLENTY
OFF DEEP MOISTURE AND AT LEAST SOME SYNOPTIC LIFT IN THE DEFORMATION
ZONE. DO NOT WANT TO TOTALLY BUY OFF ON THE LATEST ECMWF YET AS IT
IS STILL BY FAR THE FURTHEST N AND W...BUT THERE CERTAINLY EXISTS A
POSSIBILITY OF PLOWABLE SNOWFALL FOR MUCH OF THE EASTERN HALF /OR
PERHAPS THE ENTIRE CWFA/ SUNDAY...AND PERHAPS A SIGNIFICANT SNOW FOR
THE FAVORABLE LAKE ENHANCED AREAS. BOTTOM LINE THOUGH...THERE IS
STILL A GREAT AMOUNT OF UNCERTAINTY SO STAY TUNED...
OTHERWISE...BEHIND THIS SYSTEM THE WEATHER QUIETS DOWN WITH A BROAD
LONG WAVE TROUGH SETTLING ACROSS NORTH AMERICA. EXPECT SOME LAKE
EFFECT MONDAY AS THE MAIN SHORT WAVE TROUGH PASSES THROUGH WITH
LINGERING MOISTURE AND 850MB TEMPS AROUND -20C. HOWEVER...THE SFC
RIDGE QUICKLY BUILDS IN BY TUE MORNING WHICH SHOULD END ANY LES.
COULD BE QUITE A COLD MORNING ON CHRISTMAS EVE MORNING WITH THE
RIDGE OVERHEAD AND CLEARING SKIES. WILL GO WITH TEMPS WELL BELOW
ZERO FOR MOST INTERIOR LOCATIONS. MAY BE ONE OF THOSE -20F MORNINGS
IN THE NORMALLY COLDER SPOTS IF IT STAYS CLEAR AND CALM. SOME LIGHT
SNOW IS POSSIBLE LATER ON CHRISTMAS EVE INTO CHRISTMAS DAY AS THE
FRONTAL SYSTEM MOVES INTO THE AREA ASSOCIATED WITH A FAIRLY POTENT
LOOKING SHORT WAVE TROUGH...BUT DETAILS ARE TOUGH TO PIN DOWN. TEMPS
IN THE EXTENDED STILL LOOK BELOW NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 640 AM EST THU DEC 19 2013
A DEPARTING LOW PRESSURE SYSTEM WILL PULL COLDER AIR ACROSS LAKE
SUPERIOR THIS MORNING AND SHOULD LEAD TO THE DEVELOPMENT OF -SHSN
OVER THE NEXT COUPLE OF HOURS. ALTHOUGH THERE HAVE BEEN LIMITED
REPORTS OF SNOW THUS FAR...WOULD EXPECT SOME MVFR VISIBILITY
RESTRICTIONS TO GO WITH THE LOW END MVFR CEILINGS. VEERING WINDS TO
THE NORTH-NORTHEAST THROUGH THE DAY SHOULD DIMINISH SNOW CHANCES
THIS AFTERNOON AT KCMX/KIWD...BUT LEAD TO MORE FAVORABLE CONDITIONS
FOR KSAW.
A DISTURBANCE SLIDING ACROSS UPPER MICHIGAN TONIGHT WILL LEAD TO A
3-5HR BURST OF SNOW AT ALL TAF SITES. THINK KIWD/KSAW WILL SEE THE
WORST CONDITIONS AND TRENDED THEM DOWN TO IFR CEILINGS/VISIBILITIES.
EXPECT IMPROVEMENT IN THE OVERNIGHT HOURS FROM WEST TO
EAST...ALTHOUGH ALL SITES WILL STILL SEE LIGHT SNOW SHOWERS AND MVFR
CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 452 AM EST THU DEC 19 2013
A LOW DEPARTING EASTERN LAKE SUPERIOR THIS MORNING HAS LED TO AN
INCREASE IN NORTHWEST TO NORTHERLY WINDS ACROSS WESTERN LAKE
SUPERIOR EARLY THIS MORNING AND IT SHOULD SPREAD EAST ACROSS THE
REST OF THE LAKE THROUGH THE MORNING HOURS. ALTHOUGH THERE MAY BE A
FEW GUSTS TO THE 30KT RANGE THIS MORNING...WOULD EXPECT THEM TO
MAINLY BE AROUND 25KTS. A HIGH PRESSURE RIDGE BUILDING OVER
SOUTHERN ONTARIO THIS AFTERNOON WILL WEAKEN THE WINDS THROUGH THE
AFTERNOON AND NIGHT (TO BELOW 20KTS) AS A WEAK LOW TRACKS THROUGH
SOUTHERN LOWER MICHIGAN. THIS HIGH PRESSURE RIDGE WILL CROSS THE
UPPER GREAT LAKES ON FRIDAY AND FRIDAY NIGHT AND LEAD TO CONTINUED
WINDS BELOW 20KTS THROUGH THE FIRST HALF OF THE WEEKEND. A STRONGER
LOW EXITING THE SOUTHERN PLAINS ON SATURDAY AFTERNOON WILL MOVE
THROUGH SOUTHEAST LOWER MICHIGAN ON SUNDAY AND WILL INCREASE
NORTHERLY WINDS ACROSS THE LAKE. AT THIS TIME...EXPECT WINDS TO BE
AROUND 30KTS WITH A FEW GALE FORCE GUSTS TO 35KTS BEFORE DIMINISHING
SUNDAY NIGHT INTO MONDAY.
FINALLY...FREEZING SPRAY WILL BE POSSIBLE DURING THE TIMES OF
STRONGER WINDS...LARGELY TODAY AND LATE SATURDAY NIGHT INTO SUNDAY
NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...MRD
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
453 AM EST THU DEC 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 452 AM EST THU DEC 19 2013
A 1005MB LOW PRESSURE OVER EASTERN LAKE SUPERIOR CONTINUES TO
QUICKLY SLIDE EAST THIS MORNING...AS AN ASSOCIATED 925/850MB TROUGH
EXITS THE UPPER GREAT LAKES REGION. THIS QUICK DEPARTURE HAS LED TO
WINDS TURNING TO THE NORTHWEST OVER THE WESTERN LAKE AND AN AREA OF
MVFR CLOUDS (PICKED UP WELL IN THE RH FIELDS OF THE RAP ANALYSIS)
DROPPING SOUTHEAST ACROSS WESTERN AND NORTH CENTRAL UPPER MICHIGAN.
CEILINGS HAVE BEEN LOWERING FAIRLY STEADILY AT KCMX OVER THE LAST
COUPLE OF HOURS AND WITH THE RAP INDICATING 925MB TEMPS FALLING TO
-10C OVER WESTERN LAKE SUPERIOR...HAVE BEEN SEEING INDICATIONS ON
SATELLITE THAT LAKE EFFECT CLOUDS HAVE BEEN DEVELOPING. HAVEN/T
SEEN ANY PRECIPITATION NOTED AT CMX OR ON WEBCAMS OVER THE
KEWEENAW...BUT WOULD EXPECT LIGHT SNOW OR FREEZING DRIZZLE TO START
SHORTLY.
FOR TODAY...WITH THE LOW SLIDING EAST EARLY THIS MORNING AND THE
MAIN SHORTWAVE TO THE NORTHWEST OF LAKE SUPERIOR JUST BRUSHING THE
NORTHERN PART OF THE LAKE...THERE APPEARS TO BE LITTLE SYNOPTIC
FORCING ACROSS THE AREA FOR MUCH OF THE DAY. OTHER THAN THE
POTENTIAL FOR A BRIEF STRONGER SHOWERS MOVING ACROSS EASTERN LAKE
SUPERIOR WITH THE FRONT AND WIND SHIFT TO THE NORTHWEST.
OTHERWISE...THE COLDER AIR DROPPING SOUTHEAST ACROSS LAKE SUPERIOR
(925MB TEMPS FALLING TO -13C BY 00Z FRIDAY) WILL LEAD TO AN INCREASE
IN LIGHT LAKE EFFECT PRECIPITATION THIS MORNING. WITH A HIGH
PRESSURE RIDGE LOCATED JUST TO THE NORTH OF LAKE SUPERIOR TODAY
WILL LEAD TO WINDS VEERING TO THE NORTH-NORTHEAST THROUGH THE DAY.
THIS ANTI-CYCLONIC FLOW ACROSS THE LAKE WON/T BE TOO FAVORABLE FOR
LAKE EFFECT...WHICH WILL COMBINE WITH THE STRONG POCKET OF DRY
AIR ABOVE 850MB (INVERSION HEIGHTS AROUND 4KFT) ASSOCIATED WITH THE
HIGH TO KEEP ANY PRECIPITATION LIGHT. THERE IS SOME CONCERN ON SOME
FREEZING DRIZZLE MIXING WITH THE SNOW FOR THE FIRST PART OF THE
MORNING NEAR LAKE SUPERIOR AND HAVE TRIED TO FOLLOW THE TIMING OF
THE 925MB AROUND -9/-10C TO MARK THE TRANSITION TO ALL SNOW THIS
MORNING. AS FOR AMOUNTS...THINK A DUSTING TO AN INCH SEEMS
REASONABLE...WITH THE MOST IN THE FAVORED NORTH-NORTHEAST UPSLOPE
LOCATIONS OF NORTH CENTRAL UPPER MICHIGAN.
FOR TONIGHT...A QUICK MOVING DISTURBANCE WILL MOVE ACROSS UPPER
MICHIGAN IN THE WESTERLY FLOW ALOFT. IN ADDITIONS TO THE
SHORTWAVE...THE UPPER GREAT LAKES REGION WILL BE UNDER THE
FAVORABLE RIGHT REAR OF A 160KT UPPER JET AND PROVIDE DECENT
SUPPORT ALOFT FOR A SWATH OF SNOW TO MOVE ACROSS THE CWA. AT THE
SURFACE...A WEAK INVERTED TROUGH DOES LOOK TO DEVELOP OVER CENTRAL
UPPER MICHIGAN...WITH WILL HELP KEEP THE LOW LEVEL (950-900MB) FLOW
FOCUSED OVER NORTH CENTRAL UPPER MICHIGAN TO PROVIDE LAKE
ENHANCEMENT. MODELS HAVE BEEN FAIRLY CONSISTENT ON THE SWATH OF
SNOW/QPF MOVING EAST ACROSS THE CWA AROUND MID EVENING AND THEN
QUICKLY DEPARTION ABOUT HALFWAY THROUGH THE OVERNIGHT HOURS.
A GENERAL CONSENSUS IS FOR 0.1-0.15IN OF QPF MOVING ACROSS
CENTRAL/SOUTHERN UPPER MICHIGAN TONIGHT (ONLY 0.05-0.10 OVER THE
KEWEENAW) AND HAVE FOLLOWED THAT FOR THE SYNOPTIC QPF. ONE ITEM TO
NOTE IS THAT THAT DRY POCKET OF AIR BETWEEN 850-700MB WILL NEED TO
BE OVERCOME BEFORE THE SNOW CAN START. FORTUNATELY...THE FLOW IN
THAT LAYER IS FAIRLY LIGHT AND SHOULD ALLOW IT TO QUICKLY MOISTEN.
THEN...WITH THAT FAVORABLE NORTHEAST UPSLOPE AND LAKE ENHANCED
FLOW...ADJUSTED VALUES UP OVER THE HIGHER TERRAIN OF THE NORTH
CENTRAL U.P. FROM THE HURON MOUNTAINS THROUGH NEGAUNEE/GWINN. THE
TRICKY PART IN THE FORECAST COMES FROM PINNING DOWN SNOW RATIOS.
WITH MUCH OF THE BROAD MID LEVEL FGEN FOCUSED WITHIN THE
DGZ...WOULD EXPECT THERE TO BE A 3-4HR PERIOD OF SNOW RATIOS AROUND
20-1 BEFORE A DOWNWARD TREND ONCE THE BETTER FORCING DEPARTS. COBB
OUTPUT AWAY FROM THE LAKE ENHANCEMENT SUPPORTS THAT IDEA AND WITH
THAT DGZ LAYER BEING FAIRLY ISOTHERMAL...HAVE CONTINUED THOSE
RATIOS IN THE FORECAST. IN THE LAKE ENHANCEMENT AREA...THERE ARE
HINTS OF BETTER FORCING BELOW THE DGZ THAT COULD LEAD TO SLIGHTLY
LOWER RATIOS...BUT WONDERING IF THAT MAY BE A TOUCH TOO LOW AS IT
BEING ABOUT 1KFT HIGHER IT WOULD BE IN THE DGZ. THUS...OPTED TO
KEEP THE HIGHER RATIOS IN THE LAKE/TERRAIN ENHANCED AREAS TOO. THIS
LEADS TO A WIDESPREAD 1-3 INCH SNOWFALL FOR MUCH OF UPPER
MICHIGAN...WITH SOME LOCALLY HIGHER AMOUNTS IN THE NORTH CENTRAL.
DEBATED AN ADVISORY FOR MARQUETTE COUNTY FOR AN AVERAGE MORE LIKE
2-4INCHES...BUT OPTED TO DO AN SPS FOR THE ENTIRE CWA INSTEAD.
THERE WERE 2 MAIN REASONS FOR NOT GOING WITH AN ADVISORY.
ONE...SINCE THE MAIN SNOW WILL LIKELY FALL BETWEEN 10PM AND
3AM...THE IMPACTS ON THE POPULATION WILL BE LOWER AND THERE SHOULD
STILL BE ENOUGH TIME TO TREAT THE ROADS BEFORE THE MORNING COMMUTE.
THE SECOND IS A COMBINATION ON UNCERTAINTY WITH SNOW RATIOS AND QPF
AMOUNTS...WHICH BEING OFF BY A COUPLE HUNDREDTHS AT 20 TO 1 COULD
QUICKLY LOWER AMOUNTS. GOING FORECAST WAS FAIRLY SIMILAR TO THE 00Z
NAM AND LOCAL WRF-ARW RUNS...BUT THE 06Z NAM THAT JUST ARRIVED HAS
DROPPED QPF AMOUNTS IN THE ENHANCED AREAS BY 0.07IN. THUS...FELT
HOLDING OFF ON A BORDERLINE ADVISORY WAS WARRANTED AND WILL PASS
CONCERNS TO DAYSHIFT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 452 AM EST THU DEC 19 2013
ANY REMAINING MOISTURE AND LIFT RAPIDLY MOVES SOUTH AND EAST ON
FRIDAY MORNING AS A WEAK RIDGE AXIS BUILDS ACROSS LAKE SUPERIOR.
THIS SHOULD ALLOW ANY SNOW SHOWERS OFF THE LAKE TO END QUICKLY IN
THE MORNING. THERE IS A HINT OF LINGERING DEEP MOISTURE ACROSS FAR
SOUTHERN UPPER MI FRI IN THE DEFORMATION ZONE...WITH THE NAM AND
ECMWF SHOWING WEAK MID-LEVEL Q-VECTOR CONVERGENCE THROUGH THE DAY.
HOWEVER...WITH LACK OF SIGNIFICANT LOW LEVEL LIFT AND FAIRLY STRONG
CONFLUENCE ALOFT...WILL LIMIT ANY POPS TO JUST SLIGHT CHANCE ON
FRIDAY ACROSS THE FAR SOUTH.
ON FRIDAY NIGHT INTO SATURDAY...ANOTHER WEAK UPPER TROUGH ROTATES
THROUGH THE AREA. WITH REMAINING MOISTURE ACROSS THE FAR SOUTH FRI
NIGHT...WILL MAINTAIN LOW CHANCE POPS MAINLY IN MENOMINEE COUNTY BUT
AGAIN THE LIFT IS MINIMAL AT BEST. THE NAM SEEMS TO BE AN OUTLIER IN
DEVELOPING A WEAK AREA OF LOW PRESSURE ALONG THE FRONT OVER LAKE
SUPERIOR AND KEEPING IT NEARLY STATIONARY THROUGH SATURDAY BEFORE
MERGING WITH THE DEVELOPING LOW OVER THE SOUTHERN PLAINS SATURDAY
NIGHT. IN FACT...THE NAM ACTUALLY SHOWS ON LAKE MICHIGAN LAKE EFFECT
DEVELOPING IN SCHOOLCRAFT AND DELTA COUNTIES SATURDAY DUE TO THE
SOUTHERLY FLOW AHEAD OF THE LOW. MEANWHILE...THE ECMWF AND THE GFS
SUGGEST A WEAK OPEN WAVE AT BEST WITH MUCH LESS MOISTURE AND LITTLE
IF ANY QPF ON SATURDAY. GIVEN THE WEAK DYNAMICS AT BEST AND THAT THE
NAM IS THE OUTLIER...WILL GENERALLY FOLLOW THE ECMWF SOLUTION AND
KEEP LIMIT ANY POPS TO SLIGHT CHANCE FOR SATURDAY.
FOR THE SOUTHERN STREAM SYSTEM SAT NIGHT INTO SUNDAY NIGHT MOVING
THROUGH THE SOUTHERN GREAT LAKES...THE 18/12Z RUNS STARTED TO TREND
NORTH AND WEST WITH THE LOW. THE 19/00Z RUNS HAVE GENERALLY
CONTINUED THIS TREND WITH THE 19/00Z ECMWF SHIFTING EVEN FURTHER
NORTH AND WEST. WITH THE SYSTEM CLOSING OFF OVER THE SOUTHWESTERN
STATES...WOULD EXPECT THAT THE SYSTEM OVERALL WILL EJECT OUT INTO
THE PLAINS A LITTLE SLOWER THAN THE MODELS SUGGEST. THIS WOULD ALLOW
THE NORTHERN STREAM ENERGY TO POTENTIALLY PHASE WITH THE SOUTHERN
STREAM ENERGY FURTHER NORTH AND WEST...CAUSING THE LOW TO ALSO TRACK
A LITTLE FURTHER NORTH/WEST. AS SUCH...HAVE OPTED TO BRING LIKELY
POPS ACROSS THE ENTIRE EAST HALF OF UPPER MICHIGAN ON SUNDAY/SUNDAY
NIGHT AND RAISE POPS TO NEAR CATEGORICAL IN NORTH CENTRAL UPPER MI.
THIS TYPE OF TRACK WOULD ALLOW FOR A SETUP FOR DECENT LAKE
ENHANCEMENT IN THOSE AREAS FAVORED BY NORTHERLY WINDS WITH PLENTY
OFF DEEP MOISTURE AND AT LEAST SOME SYNOPTIC LIFT IN THE DEFORMATION
ZONE. DO NOT WANT TO TOTALLY BUY OFF ON THE LATEST ECMWF YET AS IT
IS STILL BY FAR THE FURTHEST N AND W...BUT THERE CERTAINLY EXISTS A
POSSIBILITY OF PLOWABLE SNOWFALL FOR MUCH OF THE EASTERN HALF /OR
PERHAPS THE ENTIRE CWFA/ SUNDAY...AND PERHAPS A SIGNIFICANT SNOW FOR
THE FAVORABLE LAKE ENHANCED AREAS. BOTTOM LINE THOUGH...THERE IS
STILL A GREAT AMOUNT OF UNCERTAINTY SO STAY TUNED...
OTHERWISE...BEHIND THIS SYSTEM THE WEATHER QUIETS DOWN WITH A BROAD
LONG WAVE TROUGH SETTLING ACROSS NORTH AMERICA. EXPECT SOME LAKE
EFFECT MONDAY AS THE MAIN SHORT WAVE TROUGH PASSES THROUGH WITH
LINGERING MOISTURE AND 850MB TEMPS AROUND -20C. HOWEVER...THE SFC
RIDGE QUICKLY BUILDS IN BY TUE MORNING WHICH SHOULD END ANY LES.
COULD BE QUITE A COLD MORNING ON CHRISTMAS EVE MORNING WITH THE
RIDGE OVERHEAD AND CLEARING SKIES. WILL GO WITH TEMPS WELL BELOW
ZERO FOR MOST INTERIOR LOCATIONS. MAY BE ONE OF THOSE -20F MORNINGS
IN THE NORMALLY COLDER SPOTS IF IT STAYS CLEAR AND CALM. SOME LIGHT
SNOW IS POSSIBLE LATER ON CHRISTMAS EVE INTO CHRISTMAS DAY AS THE
FRONTAL SYSTEM MOVES INTO THE AREA ASSOCIATED WITH A FAIRLY POTENT
LOOKING SHORT WAVE TROUGH...BUT DETAILS ARE TOUGH TO PIN DOWN. TEMPS
IN THE EXTENDED STILL LOOK BELOW NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1228 AM EST THU DEC 19 2013
OVERNIGHT...EXPECT MVFR CLOUDS TO DEVELOP AT ALL THE TAF SITES AS
MOISTURE MOVES IN JUST AHEAD OF LOW NOW MOVING INTO WRN LAKE
SUPERIOR. MAY EVEN SEE SOME LGT SNOW OR FREEZING DRIZZLE AT CMX OR
IWD LATE TONIGHT TOWARD DAYBREAK ON THURSDAY. THERE IS A BETTER
CHANCE FOR SNOW SHOWERS...STAYING MAINLY IN THE MVFR FLIGHT
CATEGORY...ON THURSDAY AT ALL THE TAF SITES AS COLDER AIR MOVING IN
BEHIND THE LOW PRESSURE SYSTEM RESULTS IN SOME LIGHT LAKE EFFECT
SNOW SHOWERS. SLIGHT IMPROVEMENT IN VSBY/CIGS CAN BE EXPECTED MAINLY
AT KIWD AND KCMX THIS AFTERNOON AS WINDS VEER FROM N TO MORE
DOWNSLOPE NE DIRECTION...BUT STILL EXPECT MVFR CONDITIONS. SYSTEM
SNOW WILL MOVE BACK IN THU EVENING LOWERING VBSYS BACK DOWN NEAR 3
SM.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 452 AM EST THU DEC 19 2013
A LOW DEPARTING EASTERN LAKE SUPERIOR THIS MORNING HAS LED TO AN
INCREASE IN NORTHWEST TO NORTHERLY WINDS ACROSS WESTERN LAKE
SUPERIOR EARLY THIS MORNING AND IT SHOULD SPREAD EAST ACROSS THE
REST OF THE LAKE THROUGH THE MORNING HOURS. ALTHOUGH THERE MAY BE A
FEW GUSTS TO THE 30KT RANGE THIS MORNING...WOULD EXPECT THEM TO
MAINLY BE AROUND 25KTS. A HIGH PRESSURE RIDGE BUILDING OVER
SOUTHERN ONTARIO THIS AFTERNOON WILL WEAKEN THE WINDS THROUGH THE
AFTERNOON AND NIGHT (TO BELOW 20KTS) AS A WEAK LOW TRACKS THROUGH
SOUTHERN LOWER MICHIGAN. THIS HIGH PRESSURE RIDGE WILL CROSS THE
UPPER GREAT LAKES ON FRIDAY AND FRIDAY NIGHT AND LEAD TO CONTINUED
WINDS BELOW 20KTS THROUGH THE FIRST HALF OF THE WEEKEND. A STRONGER
LOW EXITING THE SOUTHERN PLAINS ON SATURDAY AFTERNOON WILL MOVE
THROUGH SOUTHEAST LOWER MICHIGAN ON SUNDAY AND WILL INCREASE
NORTHERLY WINDS ACROSS THE LAKE. AT THIS TIME...EXPECT WINDS TO BE
AROUND 30KTS WITH A FEW GALE FORCE GUSTS TO 35KTS BEFORE DIMINISHING
SUNDAY NIGHT INTO MONDAY.
FINALLY...FREEZING SPRAY WILL BE POSSIBLE DURING THE TIMES OF
STRONGER WINDS...LARGELY TODAY AND LATE SATURDAY NIGHT INTO SUNDAY
NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...MRD
AVIATION...VOSS
MARINE...SRF
AREA FORECAST DISCUSSION
NWS DULUTH MN
346 AM CST THU DEC 19 2013
.SYNOPSIS...
ISSUED AT 345 AM CST THU DEC 19 2013
THE STRONG COLD FRONT THAT MOVED THROUGH THE AREA THIS AFTERNOON HAS
PUSHED WELL SOUTH OF THE FORECAST AREA AS OF 3AM. THE SURFACE LOW IS
NOW OVER EASTERN LAKE SUPERIOR...WITH THE FRONT DRAPED ACROSS
WISCONSIN AND IOWA...SOUTHWEST TO A DEVELOPING SURFACE LOW OVER
SOUTHEAST COLORADO. PRESSURE RISES OVER NORTHERN MINNESOTA HAVE
PRODUCED NORTHWEST WINDS OF 5 TO 15KTS OVER THE AREA. TEMPERATURES
FROM ZERO TO 5 ABOVE HAVE COMBINED WITH WINDS TO PRODUCE WIND CHILL
VALUES APPROACHING 20 BELOW.
&&
.SHORT TERM...(TODAY...TONIGHT AND FRIDAY)
ISSUED AT 345 AM CST THU DEC 19 2013
MAIN CONCERN THE NEXT 36 HOURS TO BE ON THE SNOW EXPECTED TO MOVE
ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA THURSDAY NIGHT.
TODAY...THE COLD FRONT WILL REMAIN DRAPED WELL SOUTH OF THE AREA
WITH A COLD AIRMASS OVER THE REGION. SURFACE WINDS WILL SLOWLY TURN
TO THE NORTH...AND EVENTUALLY NORTH-NORTHEAST BY THE END OF THE
DAY. LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO DEVELOP ALONG THE
SOUTH LAKE SHORE BY MID TO LATE MORNING...WITH SOME LIGHT
ACCUMULATIONS EXPECTED DURING THE DAY. EARLY THIS MORNING...COLD
TEMPERATURES IN THE SINGLE DIGITS AND WINDS HAVE BEEN STRONG ENOUGH
TO PRODUCE SOME RATHER CHILLY WIND CHILL VALUES...BUT ONLY JUST
APPROACHING ADVISORY CRITERIA. THUS...HAVE CANCELLED THE WIND CHILL
ADVISORY WE HAD OUT.
THE STORM WE HAVE BEEN WATCHING FOR SOME TIME WILL SLOWLY MOVE OUT
ACROSS THE PLAINS TODAY AND ACROSS THE MIDWEST TONIGHT. AN UPPER
LEVEL SHORTWAVE WILL MOVE ACROSS THE US/CANADIAN BORDER...AND THE
SURFACE LOW OVER SOUTHEAST COLORADO THIS MORNING WILL RIPPLE
NORTHEAST ALONG THE SURFACE BOUNDARY...MOVING ACROSS MISSOURI AND
ILLINOIS TONIGHT. A BAND OF STRONG FRONTOGENESIS...WARM AIR
ADVECTION ISENTROPIC LIFT WILL MOVE ACROSS MINNESOTA AND WISCONSIN
TONIGHT. LIGHT SNOW IS EXPECTED TO MOVE INTO THE SOUTHERN PORTIONS
OF THE FORECAST AREA LATE THIS AFTERNOON...AND THEN AFFECT THE
SOUTHERN THIRD OF THE FORECAST AREA TONIGHT WITH LIGHT SNOW. THE
BEST LIFT MOVES ACROSS THE AREA BETWEEN 00Z AND 06Z TONIGHT. QPF
VALUES ARE THE MAIN LIMITING FACTOR...WITH GENERALLY A TENTH OF AN
INCH OR LESS EXPECTED ALONG THE SOUTHERN PORTIONS OF THE FORECAST
AREA. WITH SNOW WATER RATIOS UP OVER 20 TO 1 IN THIS COLD
AIRMASS...WE ARE LOOKING AT A 1 TO 3 INCH SNOWFALL EVENT THIS
EVENING.
SNOW TO MOVE OUT OF THE AREA QUICKLY THURSDAY NIGHT...AND ONLY
EXPECT SOME LIGHT SNOW OVER NORTHWEST WISCONSIN FRIDAY MORNING AS
THE SURFACE RIDGE BUILDS INTO THE AREA. TEMPERATURES TO REMAIN
CHILLY WITH HIGHS RANGING FROM THE SINGLE DIGITS NORTH...TO TEENS
SOUTH.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 345 AM CST THU DEC 19 2013
ACTIVE CYCLONIC FLOW PATTERN CONTINUES ALOFT WITH COMPLEX SFC
FEATURES EARLY IN THE EXTENDED PERIOD PROVIDING LOW SLGT CHC POPS
FRI NIGHT AND THROUGH THE DAY SATURDAY. TWO WEAK INVERTED SFC
TROUGHS...ONE FROM THE NORTH AND ONE FROM THE SOUTH...WILL INTERACT
WITH EACH OTHER DURING THIS TIME AND MAINLY ACT TO PRODUCE MOSTLY
CLOUDY SKIES...BUT ALSO HAVE THE POTENTIAL TO PRODUCE LIGHT SNOW
SHOWERS/FLURRIES. A POTENT LOW PRESSURE SYSTEM WILL LIFT FROM THE
SRN OHIO VALLEY INTO THE NE LATE SAT THROUGH SUN EVENING. THIS
SYSTEM WILL STAY MOSTLY TO THE EAST OF THE NORTHLAND...BUT THE FAR
NRN EXTENT OF THE PRECIP SHIELD COULD BRUSH PARTS OF NRN/CENTRAL WI
ON SUNDAY. THE MAIN IMPACT WITH THIS SYSTEM WILL BE THE DEVELOPMENT
OF AN EAST/NE WIND ACROSS WRN LAKE SUPERIOR. THE COMBINATION OF A
LONG FETCH AND A COOL AIR MASS ALOFT WILL PRODUCE LIGHT LES FROM THE
NORTH SHORE SOUTH INTO THE HEAD OF LAKE SUPERIOR. THE WINDOW OF
OPPORTUNITY WILL BE RELATIVELY NARROW FOR THE NORTH SHORE...SO AMTS
WILL BE LIGHT. A STRONGER PUSH OF COLDER AIR ARRIVES FROM THE NW
WITH AN INCOMING S/W SUN NIGHT. THIS WILL ACT TO ENHANCE THE LES
POTENTIAL...MAINLY ALONG THE SOUTH SHORE AS WINDS BACK TO THE N/NW
INTO EARLY MONDAY. THE FAVORED AREAS OF THE SOUTH SHORE WILL LIKELY
SEE THE MOST SNOW...BUT AMTS WILL STILL REMAIN RELATIVELY LIGHT AS
DRIER AIR MOVES IN QUICKLY ON MONDAY. HIGH PRESSURE BUILDS IN ON
MONDAY BEFORE THE NEXT CLIPPER SYSTEM DROPS IN FROM THE NW TUE AND
WED WITH ADDITIONAL CHANCES FOR SNOW SHOWERS.
TEMPERATURES WILL START OUT RELATIVELY MILD EARLY IN THE WEEKEND
WITH HIGHS IN THE SINGLE DIGITS AND TEENS ABOVE ZERO...AND OVERNIGHT
LOWS IN THE SINGLE DIGITS BELOW ZERO. HOWEVER...LATE SUNDAY A STRONG
BLAST OF ARCTIC AIR ARRIVES ONCE AGAIN AND DROPS TEMPERATURES INTO
THE TEENS AND 20S BELOW ZERO MONDAY MORNING...WITH HIGHS ON MONDAY
ONLY REACHING INTO TO AROUND ZERO. ANOTHER CHILLY NIGHT MON NIGHT
WITH LOWS IN THE SINGLE DIGITS AND TEENS BLO ZERO BEFORE A SLIGHT
WARM UP ON TUE AND WED INTO THE TEENS ABV ZERO FOR HIGHS AND SINGLE
DIGITS ABV ZERO FOR LOWS. ANOTHER COLD BLAST IS POSSIBLE BY LATE IN
THE WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1133 PM CST WED DEC 18 2013
THE COLD FRONT HAS PASSED THROUGH MUCH OF THE NORTHLAND THIS
EVENING...WITH AN AREA OF MVFR CEILINGS OCCURRING OVER PORTIONS OF
WESTERN/NORTHERN MINNESOTA. WE INCREASED THE COVERAGE/TIMING OF
MVFR CEILINGS BASED ON LATEST SATELLITE AND OBSERVATIONS. THERE
MAY BE SOME FLURRIES OR A BRIEF SNOW SHOWER THAT OCCURS...BUT
OBSERVATIONS AND RADAR SHOW LIMITED COVERAGE THOUGH. THE RUC AND
SATELLITE SUGGEST THESE LOWER CEILINGS WILL DISSIPATE OVERNIGHT OR
EARLY THURSDAY MORNING. NORTH-NORTHEAST WINDS OVER LAKE SUPERIOR
THURSDAY SHOULD CAUSE LAKE CLOUDS TO DEVELOP AND AFFECT KHYR WITH
MVFR CEILINGS.
A WEAK WAVE WILL RIDE ALONG A BAROCLINIC ZONE THURSDAY
NIGHT...SPREADING LIGHT SNOW TO AREAS ALONG AND SOUTH OF HIGHWAY
2. MVFR/IFR CONDITIONS WILL OCCUR THROUGH THE EARLY MORNING HOURS
AS THE AREA OF SNOW PASSES THROUGH.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 11 -4 10 0 / 20 50 0 10
INL -1 -18 6 -5 / 0 20 0 10
BRD 8 -7 8 -3 / 30 70 0 10
HYR 18 3 14 4 / 40 100 10 20
ASX 19 8 15 5 / 60 90 20 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 PM CST THIS EVENING FOR LSZ121-
146>148.
&&
$$
SYNOPSIS...LE
SHORT TERM...LE
LONG TERM...BJT
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
1133 PM CST WED DEC 18 2013
.UPDATE...
ISSUED AT 954 PM CST WED DEC 18 2013
A COLD FRONT WAS MOVING THROUGH OUR MINNESOTA ZONES THIS
EVENING...AND WE`VE MADE SOME ADJUSTMENTS TO SHORT TERM GRIDS...AS
WELL AS TO THURSDAY NIGHT POPS/SNOW GRIDS.
WE`VE HAD TO ADJUST TEMPS QUITE A BIT THIS EVENING AS CLOUDS HAVE
NOT BEEN VERY WIDESPREAD ALLOWING TEMPS TO DROP IN LIGHT WINDS
JUST AHEAD OF THE FRONTAL BOUNDARY. THE TEMP CURVE WILL BE A
CHALLENGE TONIGHT...AS WE EXPECT TEMPS TO START TO RISE FOR A TIME
THIS EVENING/EARLY MORNING WHERE THEY HAD DROPPED SHARPLY EARLIER
THIS EVENING. THIS IS DUE TO THICKENING CLOUDS AND INCREASING WINDS.
TEMPS WILL THEN DROP AGAIN LATE TONIGHT WITH STRONG CAA BEHIND THE
FRONT. SNOW SHOWERS WITH THE FRONT HAVE BEEN SPARSE...BUT THERE
ARE A FEW LIGHT ECHOES OUT THERE...SO WE MAINTAINED THE SMALL POPS
FOR MOST AREAS.
LATEST NAM HAS SHIFTED ITS PRECIP AREA A BIT FURTHER NORTH WITH
THE THE FGEN AREA THURSDAY NIGHT...AND GIVEN CONTINUITY AMONG THE
OTHER MODELS WE DID MAKE SOME ADJUSTMENTS TO INCREASE POPS OVER
THE SOUTHERN HALF OF THE NORTHLAND...AND INCREASED SNOW AMOUNTS A
BIT ACROSS THE FAR SOUTH.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 PM CST WED DEC 18 2013
CURRENT SFC ANALYSIS DEPICTS A WELL DEFINED COLD FRONT PUSHING
INTO NW MINN. THIS BAROCLINIC ZONE AND TRANSITION TO CAA WILL BE
THE FOCUS FOR INCREASING CLOUDS AND SCT -SN/FLURRIES OVERNIGHT.
LITTLE OR NO SNOW ACCUM IS EXPECTED. HOWEVER...VSBY MAY BE
REDUCED TO AROUND A MILE AT TIMES DUE TO THE COMBO OF FALLING SN
AND GUSTY WINDS.
HAVE ISSUED A WIND CHILL ADVISORY FOR KOOCH COUNTY LATE TONIGHT
THROUGH THURS MORNING...WITH THE LOWEST WIND CHILL VALUES EXPECTED
DURING THE 0500-1000 AM WINDOW. LATEST BUFR SOUNDINGS SHOW
INVERSION HEIGHTS INCREASE TO 3 KFT AS THE FRONT PASSES AND THE
COLD CANADIAN AIR SURGES BACK IN THE REGION. EXPECT WINDS TO
BECOME GUSTY OVERNIGHT...MAINLY AFTER 06-08Z. THE CAA WILL
CONTINUE THURSDAY...WITH TEMPS ONLY REACHING THE LOW SINGLE
DIGITS ALONG THE BORDERLAND.
HAVE KEPT SMALL CHC POPS ALONG THE SOUTH SHORE OF LAKE SUPERIOR
THURSDAY AS WINDS/LAPSE RATES BECOME FAVORABLE FOR LAKE
EFFECT/ENHANCED SNOW SHOWERS. LIMITING FACTOR FOR SNOW WILL BE
LACK OF MID-LEVEL MOISTURE AND MARGINAL INVERSION HEIGHTS ONLY
AROUND 4 KFT. THE MOISTURE AND INVERSION HEIGHTS BECOME MORE
FAVORABLE FOR LES ALONG THE SOUTH SHORE THURSDAY NIGHT.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 PM CST WED DEC 18 2013
CONFIDENCE MODERATE THIS PERIOD AS MDLS MAINTAIN GOOD CONTINUITY
REGARDING OVERALL SYNOPTIC SCALE PATTERN. TWO BRANCHES OF THE
JETSTREAM WILL AMPLIFY WITH SRN BRANCH CYCLOGENESIS EXPECTED TO
DEVELOP SOUTH AND THEN EAST OF REGION. NRN BRANCH WILL DELIVER
SEVERAL EPISODES OF COLD AIR INTO THE NEW WEEK. INITIAL SFC LOW WILL
MOVE FROM SRN PLAINS INTO NRN IL THUR NIGHT. HIGHEST POPS WILL BE
CONFINED TO SERN TIER OF CWA WHERE SOME ACCUMULATION IS EXPECTED.
LAKE CONTRIBUTION MAY ALLOW SOME EXPANSION OF PRECIP SHIELD FARTHER
NORTH TOWARD TWIN PORTS. PROGRESSIVE NATURE OF SYSTEM AND CONVERGENT
FLOW ALOFT SHOULD MINIMIZE POTENTIAL FOR SIG PRECIP WITH THIS
FEATURE. SOME QUESTION AS TO WHETHER MID LVL FRONTOGENESIS MAY
AUGMENT PRECIP FARTHER NORTH BUT TREND HAS BEEN TO KEEP
FRONTOGENESIS POTENTIAL FARTHER SOUTH. COLD AND RELATIVELY DRY WX IS
ANTICIPATED FRIDAY/SATURDAY EXCEPT IN NORTH AND EAST CWA WHERE LAKE
INFLUENCE MAY PRODUCE SOME SNOWFALL. A SECOND AND MORE POTENT SFC
LOW WILL ORGANIZE OVER LOWER MS VALLEY SAT EVENING AND AIM TOWARDS
WRN IN BY EARLY SUNDAY. AS THIS SYSTEM MOVES NORTHEAST THE SOMEWHAT
PHASED BRANCHES OF THE UPPER JET SHOULD ALLOW FOR DEVELOPMENT OF AN
INVERTED SFC TROUGH INTO ERN HALF OF CWA. SFC LOW WINDS UP OVER ERN
GT LAKES SUNDAY. THE INVERTED SFC TROUGH IS FCST TO EXTEND WELL
WESTWARD INTO ERN CWA AS UPPER TROUGH IN NRN BRANCH MIGRATES
OVERHEAD. LATEST FCST OF SFC PRESSURE PATTERN WOULD FAVOR AN
EXTENDED PERIOD OF LES POTENTIAL ACROSS THE SOUTH SHORE FROM SUNDAY
INTO MONDAY. INITIAL GLANCE AT INSTABILITY/INVERSION HEIGHT/DEEP
LAYER MOISTURE PARAMETERS SUGGEST SIG ACCUMULATION POTENTIAL. THE
FCST WIND DIRECTION ALLOWS CONSIDERABLE FETCH INTO
BAYFIELD/IRON/ASHLAND COUNTIES ALTHOUGH IT IS TOO UNCERTAIN AT WHAT
RATE THE WIND WILL SHIFT DIRECTION AS THE SYSTEM TO THE EAST PULLS
FARTHER AWAY. TEMPS WILL REMAIN BLO CLIMO THROUGHOUT THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1133 PM CST WED DEC 18 2013
THE COLD FRONT HAS PASSED THROUGH MUCH OF THE NORTHLAND THIS
EVENING...WITH AN AREA OF MVFR CEILINGS OCCURRING OVER PORTIONS OF
WESTERN/NORTHERN MINNESOTA. WE INCREASED THE COVERAGE/TIMING OF
MVFR CEILINGS BASED ON LATEST SATELLITE AND OBSERVATIONS. THERE
MAY BE SOME FLURRIES OR A BRIEF SNOW SHOWER THAT OCCURS...BUT
OBSERVATIONS AND RADAR SHOW LIMITED COVERAGE THOUGH. THE RUC AND
SATELLITE SUGGEST THESE LOWER CEILINGS WILL DISSIPATE OVERNIGHT OR
EARLY THURSDAY MORNING. NORTH-NORTHEAST WINDS OVER LAKE SUPERIOR
THURSDAY SHOULD CAUSE LAKE CLOUDS TO DEVELOP AND AFFECT KHYR WITH
MVFR CEILINGS.
A WEAK WAVE WILL RIDE ALONG A BAROCLINIC ZONE THURSDAY
NIGHT...SPREADING LIGHT SNOW TO AREAS ALONG AND SOUTH OF HIGHWAY
2. MVFR/IFR CONDITIONS WILL OCCUR THROUGH THE EARLY MORNING HOURS
AS THE AREA OF SNOW PASSES THROUGH.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 1 13 -3 10 / 20 10 50 10
INL -11 2 -18 6 / 50 0 10 0
BRD 1 10 -6 8 / 20 10 60 0
HYR 6 18 7 14 / 10 20 90 10
ASX 5 19 10 15 / 20 30 60 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST THURSDAY FOR MNZ010.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 PM CST THURSDAY FOR LSZ121-146>148.
&&
$$
UPDATE...MELDE
SHORT TERM...GRANING
LONG TERM...CANNON
AVIATION...MELDE
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
813 PM CST Fri Dec 20 2013
.UPDATE:
Issued at 804 PM CST Fri Dec 20 2013
We are continuing to monitor the developing winter storm. Rain
is spreading across the southeast half of the CWA on the warm side
of the freezing line, which extended from near Springfield MO to
near Pittsfield IL at 02z. Although a few minor tweaks were made
in the grids to capture the latest T/Td observations and
precipitation trends, no significant changes to the forecast are
required at this time.
Kanofsky
&&
.SHORT TERM: (Tonight through Monday)
Issued at 417 PM CST Fri Dec 20 2013
Pending winter storm will be the primary focus for this discussion.
The leading edge of the arctic airmass is moving through the area at
this time. Temperatures are falling quickly behind the front from
the mid and upper 60s through the 40s. This cold air will set the
stage for wintry precip tonight through Sunday morning. There are
only some small tweaks to the going winter weather forecast. The
front will stall over southeast Missouri tonight, and a 50-60kt low
level jet will bring copious amounts of Gulf moisture up into the
Mid-Mississippi Valley. Waves of rain will develop as the low level
jet impinges on the baroclinic zone stalled over the region.
Forecast soundings continue to indicate that the low level cold
layer will be very shallow, which is the perfect setup for freezing
rain. Surface temperatures should fall below freezing in central
and northeast Missouri as well as west central Illinois. Freezing
rain will continue on Saturday into Saturday night. Luckily the
heaviest rain will be south of the freezing line across southeast
Missouri and southern Illinois. As it is, 1 to 3 tenths of an inch
of ice are expected to accumulate across the area and the winter
storm watch has been upgraded to a warning, with a band of advisory
on the southeast side to account for the lighter accumulations. The
accumulations on the east side of the heavy icing are still
uncertain. It will all depend on the surface temperature which
continues to waver very near freezing across much of central and
northeast Missouri on Saturday. Hourly temperatures are expected to
rise to 32-33, either through diurnal heating or by the release of
latent heat through freezing. Regardless, forecasting the eastern
extent of the icing will continue to be challenging even as the
event is on going.
The scenario for Saturday night is still basically the same as
well. The shortwave ejects northeast across the area overnight and
a strong def-zone develops back across western Missouri. The
eastern extent of the heavy snow still looks to be mostly out of our
area. Have tweaked snow amounts a bit and added in a little sleet
in parts of central and northeast Missouri Saturday evening as
forecast soundings are showing a slightly deeper cold layer than
previously forecast. 1 to 4 inches of snow/sleet with the higher
amounts in northeast Missouri still looks good. Any lingering snow
should wrap up early Sunday morning.
Another strong cold high pressure system will slide southeast across
the Northern Plains into the Mississippi Valley Sunday night and
Monday. Besides the very cold air which this airmass will bring to
the region, the pressure gradient will tighten between the high and
the storm to the east which will bring the winds up to 10 to 20 mph
Sunday night. If there is substantial ice cover over parts of the
area the higher winds could cause tree and power line damage even
after the precipitation has ended.
Carney
.LONG TERM: (Saturday through Next Friday)
Issued at 417 PM CST Fri Dec 20 2013
With mean long wave trof remaining over the central CONUS,
temperatures over the CWA should be below average for much of the
Tue-Fri time frame. Medium range solutions are in good agreement
that the first strong cold air surge will occur Monday
night-Tuesday, with a second in the Thursday-Thursday night time
frame. Between these there should be a brief moderation in temps on
Christmas Day, when shortwave zipping through the trof brings a
quick shot of warmer air to the mid-Mississippi Valley, as well as
some low snow chances (in the slight chance/low chance
range).
Truett
&&
.AVIATION: (For the 00z TAFs through 00z Saturday Evening)
Issued at 535 PM CST Fri Dec 20 2013
Primary concerns for this valid TAF period will be onset of
precipitation. IFR ceilings behind the cold front will continue to
push south and eastward through the evening hours and will likely
remain between 300 and 700 feet through the valid TAF period.
Current radar imagery depicts an area of scattered SHRA which may
impact the metro terminals through 0200 UTC. Believe steadier rain
should however arrive closer to the midnight hour which matches up
well with both the HRRR and RAP guidance. Precipitation will start
later at COU and UIN...likely at COU just after midnight and UIN
a few hours later. With temperatures below freezing at these
locations...precipitation type will be FZRA due to stout warm
layer aloft. Temperatures are likely to stay at or just below
freezing through tomorrow evening so have left PTYPE as freezing
rain for both COU and UIN. Further to the southeast...cannot rule
out some FZRA as temperatures by early morning may approach the
freezing mark...but confidence in this scenario is too low to put
in TAFs. Will monitor progress of subfreezing air this evening.
Specifics for KSTL:
Primary concerns for this valid TAF period will be onset of
precipitation. IFR ceilings behind the cold front will continue to
push south and eastward through the evening hours and will likely
remain between 500 and 700 feet through the valid TAF period.
Current radar imagery depicts an area of scattered SHRA which may
impact Lambert Field through 0200 UTC so have VCSH mentioned. Believe
steadier rain should however arrive closer to the midnight hour
which matches up well with both the latest HRRR and RAP guidance.
Rainfall intensity should intensify tomorrow morning and into
early afternoon before becoming lighter again tomorrow evening. Cannot
rule out some FZRA as temperatures by early morning may approach
the freezing mark...but confidence in this scenario is too low to
put in TAF. Will monitor progress of subfreezing air this evening.
Gosselin
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...FLOOD WATCH through Saturday evening FOR Crawford MO-Franklin MO-
Gasconade MO-Iron MO-Jefferson MO-Madison MO-Osage MO-
Reynolds MO-St. Charles MO-St. Francois MO-St. Louis City
MO-St. Louis MO-Ste. Genevieve MO-Warren MO-Washington MO.
FREEZING RAIN ADVISORY from Midnight tonight to 6 PM CST
Saturday FOR Gasconade MO-Lincoln MO-Osage MO-Warren MO.
WINTER STORM WARNING from Midnight tonight to 6 AM CST Sunday
FOR Audrain MO-Boone MO-Callaway MO-Cole MO-Marion MO-
Moniteau MO-Monroe MO-Montgomery MO-Pike MO-Ralls MO.
WINTER STORM WARNING from 6 AM Saturday to 6 AM CST Sunday FOR
Knox MO-Lewis MO-Shelby MO.
IL...FLOOD WATCH through Saturday evening FOR Bond IL-Clinton IL-
Fayette IL-Jersey IL-Macoupin IL-Madison IL-Marion IL-
Monroe IL-Montgomery IL-Randolph IL-St. Clair IL-Washington
IL.
FREEZING RAIN ADVISORY from Midnight tonight to 6 PM CST
Saturday FOR Calhoun IL-Greene IL-Jersey IL.
WINTER STORM WARNING from Midnight tonight to 6 AM CST Sunday
FOR Adams IL-Brown IL-Pike IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
545 PM CST Fri Dec 20 2013
.SHORT TERM: (Tonight through Monday)
Issued at 417 PM CST Fri Dec 20 2013
Pending winter storm will be the primary focus for this discussion.
The leading edge of the arctic airmass is moving through the area at
this time. Temperatures are falling quickly behind the front from
the mid and upper 60s through the 40s. This cold air will set the
stage for wintry precip tonight through Sunday morning. There are
only some small tweaks to the going winter weather forecast. The
front will stall over southeast Missouri tonight, and a 50-60kt low
level jet will bring copious amounts of Gulf moisture up into the
Mid-Mississippi Valley. Waves of rain will develop as the low level
jet impinges on the baroclinic zone stalled over the region.
Forecast soundings continue to indicate that the low level cold
layer will be very shallow, which is the perfect setup for freezing
rain. Surface temperatures should fall below freezing in central
and northeast Missouri as well as west central Illinois. Freezing
rain will continue on Saturday into Saturday night. Luckily the
heaviest rain will be south of the freezing line across southeast
Missouri and southern Illinois. As it is, 1 to 3 tenths of an inch
of ice are expected to accumulate across the area and the winter
storm watch has been upgraded to a warning, with a band of advisory
on the southeast side to account for the lighter accumulations. The
accumulations on the east side of the heavy icing are still
uncertain. It will all depend on the surface temperature which
continues to waver very near freezing across much of central and
northeast Missouri on Saturday. Hourly temperatures are expected to
rise to 32-33, either through diurnal heating or by the release of
latent heat through freezing. Regardless, forecasting the eastern
extent of the icing will continue to be challenging even as the
event is on going.
The scenario for Saturday night is still basically the same as
well. The shortwave ejects northeast across the area overnight and
a strong def-zone develops back across western Missouri. The
eastern extent of the heavy snow still looks to be mostly out of our
area. Have tweaked snow amounts a bit and added in a little sleet
in parts of central and northeast Missouri Saturday evening as
forecast soundings are showing a slightly deeper cold layer than
previously forecast. 1 to 4 inches of snow/sleet with the higher
amounts in northeast Missouri still looks good. Any lingering snow
should wrap up early Sunday morning.
Another strong cold high pressure system will slide southeast across
the Northern Plains into the Mississippi Valley Sunday night and
Monday. Besides the very cold air which this airmass will bring to
the region, the pressure gradient will tighten between the high and
the storm to the east which will bring the winds up to 10 to 20 mph
Sunday night. If there is substantial ice cover over parts of the
area the higher winds could cause tree and power line damage even
after the precipitation has ended.
Carney
.LONG TERM: (Saturday through Next Friday)
Issued at 417 PM CST Fri Dec 20 2013
With mean long wave trof remaining over the central CONUS,
temperatures over the CWA should be below average for much of the
Tue-Fri time frame. Medium range solutions are in good agreement
that the first strong cold air surge will occur Monday
night-Tuesday, with a second in the Thursday-Thursday night time
frame. Between these there should be a brief moderation in temps on
Christmas Day, when shortwave zipping through the trof brings a
quick shot of warmer air to the mid-Mississippi Valley, as well as
some low snow chances (in the slight chance/low chance
range).
Truett
&&
.AVIATION: (For the 00z TAFs through 00z Saturday Evening)
Issued at 535 PM CST Fri Dec 20 2013
Primary concerns for this valid TAF period will be onset of
precipitation. IFR ceilings behind the cold front will continue to
push south and eastward through the evening hours and will likely
remain between 300 and 700 feet through the valid TAF period.
Current radar imagery depicts an area of scattered SHRA which may
impact the metro terminals through 0200 UTC. Believe steadier rain
should however arrive closer to the midnight hour which matches up
well with both the HRRR and RAP guidance. Precipitation will start
later at COU and UIN...likely at COU just after midnight and UIN
a few hours later. With temperatures below freezing at these
locations...precipitation type will be FZRA due to stout warm
layer aloft. Temperatures are likely to stay at or just below
freezing through tomorrow evening so have left PTYPE as freezing
rain for both COU and UIN. Further to the southeast...cannot rule
out some FZRA as temperatures by early morning may approach the
freezing mark...but confidence in this scenario is too low to put
in TAFs. Will montior progress of subfreezing air this evening.
Specifics for KSTL:
Primary concerns for this valid TAF period will be onset of
precipitation. IFR ceilings behind the cold front will continue to
push south and eastward through the evening hours and will likely
remain between 500 and 700 feet through the valid TAF period.
Current radar imagery depicts an area of scattered SHRA which may
impact Lambert Field through 0200 UTC so have VCSH mentioned. Believe
steadier rain should however arrive closer to the midnight hour
which matches up well with both the latest HRRR and RAP guidance.
Rainfall intensity should intensify tomorrow morning and into
early afternoon before becoming lighter again tomorrow evening. Cannot
rule out some FZRA as temperatures by early morning may approach
the freezing mark...but confidence in this scenario is too low to
put in TAF. Will montior progress of subfreezing air this evening.
Gosselin
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...FLOOD WATCH through Saturday evening FOR Crawford MO-Franklin MO-
Gasconade MO-Iron MO-Jefferson MO-Madison MO-Osage MO-
Reynolds MO-St. Charles MO-St. Francois MO-St. Louis City
MO-St. Louis MO-Ste. Genevieve MO-Warren MO-Washington MO.
FREEZING RAIN ADVISORY from Midnight tonight to 6 PM CST
Saturday FOR Gasconade MO-Lincoln MO-Osage MO-Warren MO.
WINTER STORM WARNING from Midnight tonight to 6 AM CST Sunday
FOR Audrain MO-Boone MO-Callaway MO-Cole MO-Marion MO-
Moniteau MO-Monroe MO-Montgomery MO-Pike MO-Ralls MO.
WINTER STORM WARNING from 6 AM Saturday to 6 AM CST Sunday FOR
Knox MO-Lewis MO-Shelby MO.
IL...FLOOD WATCH through Saturday evening FOR Bond IL-Clinton IL-
Fayette IL-Jersey IL-Macoupin IL-Madison IL-Marion IL-
Monroe IL-Montgomery IL-Randolph IL-St. Clair IL-Washington
IL.
FREEZING RAIN ADVISORY from Midnight tonight to 6 PM CST
Saturday FOR Calhoun IL-Greene IL-Jersey IL.
WINTER STORM WARNING from Midnight tonight to 6 AM CST Sunday
FOR Adams IL-Brown IL-Pike IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS RALEIGH NC
930 PM EST FRI DEC 20 2013
.SYNOPSIS...SOUTH SOUTHWEST FLOW AROUND BERMUDA HIGH PRESSURE WILL
RESULT IN WARMING CONDITIONS THROUGH SUNDAY...FOLLOWED BY THE
PASSAGE OF A COLD FRONT SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 930 PM FRIDAY...
HIGH PRESSURE REMAINS ANCHORED OFF THE CAROLINA COAST THIS EVENING.
CIRRUS CONTINUES TO STREAM ACROSS THE AREA FROM THE SOUTHWEST AS
SOUTHWESTERLY UPPER LEVEL FLOW STRENGTHENS AHEAD OF A VIGOROUS STORM
SYSTEM TAKING SHAPE ACROSS THE SOUTHERN US. BASED ON SATELLITE
TRENDS...CIRRUS MAY THIN AT TIMES BUT A MAJORITY OF THE NIGHT WILL
BE MOSTLY CLOUDY. RETURN FLOW AROUND THE SURFACE HIGH MAKES STRATUS
A POSSIBILITY ONCE AGAIN...THOUGH FORECAST SOUNDINGS ARE NOT
SUGGESTING WIDESPREAD STRATUS DEVELOPMENT. THE 00Z RAOBS SHOW QUITE
A BIT MORE LOW-LEVEL MOISTURE AT KFFC THAN AT KCHS...WHICH IS WHERE
THE LOW-LEVEL FLOW IS ORIGINATING THIS EVENING. THE HRRR IS THE
MAIN MODEL SHOWING BETTER COVERAGE DEVELOPING OVER SC LATE TONIGHT
AND SPREADING ACROSS CENTRAL NC THROUGH MID-MORNING...BUT GIVEN THE
AMOUNT OF HIGH CLOUDS AND LACK OF MODEL AGREEMENT..EXPECT STRATUS
WILL BE PATCHY AND LATE TO DEVELOP. REGARDING TEMPS...CIRRUS HAS
HINDERED COOLING ALREADY THIS EVENING...AND UNLESS BETTER BREAKS IN
THE CIRRUS DEVELOP...LOWS WILL STRUGGLE TO FALL MUCH FURTHER THAN
THE UPPER 40S AND LOWER 50S IN MOST AREAS. -SMITH
SATURDAY AND SATURDAY NIGHT: THE AFOREMENTIONED COLD FRONT WILL
CONTINUE TO SLOWLY APPROACH THE REGION FROM THE WEST AS A SURFACE
WAVE OF LOW PRESSURE LIFTS FROM EASTERN TX INTO THE OHIO VALLEY
ALONG THE FRONT. WHILE LOW LEVEL CLOUD COVER SHOULD BE GREATER THAN
TODAY... AFTERNOON LOW LEVEL THICKNESS VALUES WILL INCREASE INTO THE
1380S ON SATURDAY AFTERNOON... SOME 20 METERS HIGHER THAN TODAY.
THIS SHOULD YIELD HIGH TEMPS NEAR STATISTICAL GUIDANCE (NEAR THE
WARM SIDE OF GUIDANCE)... AROUND 70 NW TO THE MID 70S
EAST/SOUTHEAST. LOWS WILL BE VERY WARM FOR THIS TIME OF YEAR WITH
AGAIN POSSIBLY SOME LOW CLOUDS. EXPECT LOWS WILL BE AROUND 60. BOTH
HIGHS AND LOWS WILL BE NEAR RECORD VALUES (RECORD HIGH MAX AND
RECORD HIGH MIN). SEE CLIMATE SECTION BELOW. WE COULD SEE SOME PRE-
FRONTAL SHOWERS AS INCREASING LOW LEVEL FLOW MAY HELP SUPPORT SOME
LIGHT SHOWERS ACROSS POINTS FROM OUR WESTERN PIEDMONT WESTWARD LATE
SATURDAY AFTERNOON INTO SATURDAY NIGHT. IF WE DO INDEED SEE ANY
PRECIP... EXPECT THE SHOWERS SHOULD BE LIGHT AND SPOTTY. FOR NOW
WILL KEEP POPS LOW FOR THIS TIME FRAME ACROSS THE WESTERN
PIEDMONT... AND NO POPS ELSEWHERE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 250 PM FRIDAY...
STRONG WARM AIR ADVECTION CONTINUES AHEAD OF THE SLOWLY APPROACHING
COLD FRONT...WITH RECORD HIGH TEMPERATURES ON SUNDAY. SHOWER
ACTIVITY WILL BE GRADUALLY SPREADING INTO THE WESTERN PIEDMONT
THROUGH THE DAY...WITH CHANCE POPS IN THE EAST BY EVENING.
STRENGTHENING IN THE LOW LEVEL JET (>50KTS) AND FAVORABLE UPPER
DIFFLUENCE WILL BE OFFSET BY MEAGER INSTABILITY...WITH NEAR
NEGLIGIBLE CAPE SUNDAY...WILL CONTINUE ONGOING ISOLATED THUNDER.
HIGHS WILL REACH MID TO UPPER 70S OVER MOST OF THE AREA.
LIKELY TO CATEGORICAL POPS WILL BE THE RULE SUNDAY NIGHT AND MONDAY
AS THE FRONT MOVES SLOWLY ACROSS THE AREA. SIMILARLY...FORCING IS
STRONG IN THE FRONTAL ZONE...OFFSET BY WEAK MID LEVEL LAPSE RATES SO
WILL CONTINUE ISOLATED THUNDER...ALLOWING FOR STRONGER WORDING AS
THE SCENARIO APPROACHES AND THE TIMING CAN BE PINNED DOWN MORE
TIGHTLY. MINS WILL BE VERY MILD SUNDAY NIGHT...MID 50S TO LOWER
60S...GIVING A HEADSTART ON MONDAYS HIGHS...WHICH WILL PEAK IN THE
60S AS THE FRONT MOVES TO A POSITION EAST OF THE AREA BY MONDAY
AFTERNOON. SHOWERS WILL LINGER IN THE EAST THROUGH PERHAPS MIDNIGHT
MONDAY NIGHT...OTHERWISE COLD AIR ADVECTION WILL BE SURGING INTO THE
AREA MONDAY NIGHT...WITH SKIES CLEARING FROM THE WEST AND TEMPS
FALLING INTO THE 30S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 25O PM FRIDAY...
CLEAR AND MUCH COOLER TUESDAY AND CHRISTMAS DAY AS HIGH PRESSURE
MIGRATES ACROSS THE OHIO VALLEY AND RIDGES DOWN THE ATLANTIC COAST.
HIGHS WILL BE IN THE LOW AND MID 40S BOTH DAYS. MORNING LOWS WILL BE
MOSTLY IN THE MID 20S CHRISTMAS MORNING.
THERE IS CONSIDERABLE UNCERTAINTY IN THE LATE WEEK PERIOD AS THE
UPCOMING COLD AIR DAMMING SCENARIO WILL ENCOURAGE DEVELOPMENT OF A
TROF ALONG THE COAST. THIS COULD LEAD TO SOME CYCLOGENESIS AND
UNSETTLED WEATHER IN THE EASTERN THIRD OF THE STATE BY FRIDAY. AT
THIS POINT AIRMASS MODIFICATION LOOK TO ALLOW HIGHS TO SNEAK BACK UP
TOWARDS THE CLIMATOLOGICAL RANGE OF UPPER 40S TO MID 50S THURSDAY
AND FRIDAY.
&&
.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
AS OF 700 PM FRIDAY...
LOW LEVEL SOUTHERLY RETURN FLOW WILL CONTINUE TO PUMP MOISTURE INTO
THE AREA OVERNIGHT... INCREASING THE THREAT OF IFR/MVFR CIGS BY
DAYBREAK...MAINLY ACROSS WESTERN AND SOUTHERN TERMINALS (AT
KGSO/KINT AND PERHAPS KFAY). CONFIDENCE REMAINS LOW AND AT THIS TIME
WILL CARRY A TEMPO GROUP FOR MVFR CEILINGS AT KFAY ONLY BASED ON
LATEST HRRR.
ANY STRATUS/SUB-VFR CIGS THAT DEVELOP COULD BE VERY SLOW TO LIFT
...BECOMING VFR BY LATE MORNING/EARLY AFTERNOON. WIND WILL AGAIN
PICK UP BY MID MORNING AS WE BEGIN TO DIURNALLY MIX... ALLOWING
SUSTAINED WINDS TO INCREASE TO 10 TO 12 KTS... WITH GUSTS OF UP TO
20 KTS POSSIBLE BY AT LEAST EARLY AFTERNOON.
LOOKING AHEAD: THE PROBABILITY OF LOW CLOUDS/STRATUS SHOULD CONTINUE
TO INCREASE SATURDAY NIGHT/SUNDAY MORNING WITHIN STRENGTHENING
MOISTURE TRANSPORT FEED FROM THE GULF...COMPLIMENTS OF A 50KT LLJ.
SHOWERS WILL BECOME MORE NUMEROUS ACROSS THE AREA FROM WEST TO EAST
LATE SUNDAY AFTERNOON AND INTO SUNDAY NIGHT WITH WIDESPREAD SUB-VFR
CONDITIONS IN RAIN...POSSIBLY HEAVY AT TIMES...CONTINUING THROUGH
MONDAY EVENING AS A SLOW MOVING COLD FRONT PUSHES EAST THROUGH THE
AREA. VFR CONDITIONS ARE EXPECTED TO RETURN BY TUESDAY AND CONTINUE
THROUGH THE REMAINDER OF THE PERIOD.
&&
.CLIMATE...
AS OF 230 PM WEDNESDAY...
DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS:
RALEIGH/DURHAM...
HIGHHI MIN
DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011
--------------------------------------------------------------------
GREENSBORO...
HIGHHI MIN
DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984
DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011
--------------------------------------------------------------------
FAYETTEVILLE...
HIGHHI MIN
DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...26
NEAR TERM...77/SMITH
SHORT TERM...26/13
LONG TERM...MLM
AVIATION...CBL
CLIMATE...RAH
AREA FORECAST DISCUSSION...UPDATED
NWS PORTLAND OR
1213 AM PST THU DEC 19 2013
.SYNOPSIS..RAIN AND SNOW SHOWERS WILL DIMINISH THROUGH THE EVENING.
CLEARING SKIES WILL DEVELOP FROM NORTH TO SOUTH TONIGHT...LEADING TO
COLDER OVERNIGHT LOWS AND THE POTENTIAL FOR ICY ROAD SURFACES FOR
TOMORROW MORNING. THERE WILL ALSO BE A FEW PATCHES OF FREEZING FOG
IN THE LOWLANDS. THERE WILL BE A BREAK IN PRECIPITATION TOMORROW
BEFORE A WARMER SYSTEM BRINGS RAIN AND MOUNTAIN SNOW ON FRI. IT
CONTINUES TO LOOK LIKE NORTHERN VALLEY LOCATIONS MAY SEE PRECIP
START AS SNOW FRI MORNING. TEMPS WILL WARM SIGNIFICANTLY LATER
FRI...WITH MODERATE TO HEAVY RAIN EXPECTED OVER MOST OF THE AREA. AN
UPPER LEVEL RIDGE WILL SET UP OVER THE NE PAC LATE IN THE
WEEK...WITH SEVERAL SYSTEMS PUSHING OVER THE TOP OF THE RIDGE
THROUGH EARLY NEXT WEEK.
&&
.UPDATE...JUST ISSUED ANOTHER QUICK FORECAST TO HANDLE THE PATCHY
FREEZING FOG DEVELOPING ACROSS THE LOWLANDS. SOME PATCHES OF
FREEZING FOG ARE BEING OBSERVED AT THE COAST NEAR ASTORIA...AS WELL
AS PORTIONS OF THE WILLAMETTE VALLEY AND SW WASHINGTON INTERIOR
LOWLANDS. ALSO DROPPED THE TEMPERATURES A FEW DEGREES...WITH RAPIDLY
CLEARING SKIES THEY HAVE FALLEN BELOW FREEZING A LITTLE FASTER THAN
PREVIOUSLY EXPECTED. WEAGLE
&&
.PREV DISCUSSION... /ISSUED 842 PM PST WED DEC 18 2013/
UPDATE...HOPEFULLY YOU ARE ALL NOT CONFUSED BY NOW BY OUR
TECHNOLOGICAL CHALLENGES...BUT THE LATEST SPECIAL WEATHER STATEMENT
FOR SLICK ROADS IS FOR TOMORROW MORNINGS COMMUTE...THURSDAY MORNING
AND NOT FRIDAY MORNING.
LATEST GRIDS ARE BEING SENT TO REFLECT LESS IN THE WAY OF FOG
TONIGHT. COLD AIR ADVECTION AND MOISTURE PROFILES DECREASING WITH
HEIGHT IN THE LOWEST LEVELS COUPLES WITH CLEARING SKIES TO SUGGEST
TEMPERATURES IN MOST PLACES WILL BE CHASING DEWPOINTS TONIGHT AND
LIMIT FOG POTENTIAL. OTHERWISE...WET ROADS AND MOST PLACES DIPPING
TO NEAR FREEZING (URBAN AREAS) OR BELOW MEANS THAT THERE WILL LIKELY
BE SOME SLICK OR ICY SPOTS ON ROADWAYS LATE TONIGHT INTO EARLY
FRIDAY.
THERE ARE SOME SHOWERS OUT THERE MOSTLY IN THE FORM OF RAIN...BUT
EXPECT TO SEE SOME SNOWFLAKES MIXED IN AT TIMES EVEN AT THE LOWEST
ELEVATIONS...AS HAS BEEN REPORTED IN ALBANY THIS EVENING. THERE ARE
SOME CONVERGENCE ZONE SHOWERS NORTH OF THE AREA THAT ARE PUSHING
THROUGH LEWIS COUNTY WASHINGTON. LATEST HRRR SUGGESTS THESE DIE OUT
BEFORE GETTING INTO OUR AREA...THOUGH POSSIBLY SOME FLAKES AS WELL
FOR COWLITZ COUNTY. /KMD
SHORT TERM...TONIGHT THROUGH SATURDAY... A COLD UPPER LEVEL TROUGH
IS BRINGING INCREASING SHOWERS AND LOWERING SNOW LEVELS ACROSS THE
REGION THIS AFTERNOON. THE BEST SHOWERS ACTIVITY IS CURRENTLY BEING
OBSERVED OVER THE S WA/N OR COAST AND COAST RANGE AND WILLAPA HILLS.
AS THE TROUGH CONTINUES TO PUSH SOUTH THE FOCUS OF THE SHOWER
ACTIVITY WILL BECOME FOCUSED OVER THE N WILLAMETTE VALLEY AND
CENTRAL OR COAST DURING THE LATE AFTERNOON...THEN OVER THE
CENTRAL/SOUTHERN VALLEY THIS EVENING. AS THE COLD AIR MOVES IN
ALOFT...SNOW LEVELS SHOULD FALL DOWN INTO THE COAST RANGE AND
CASCADE FOOTHILLS...BUT ONLY LIGHT ACCUMULATIONS ARE EXPECTED. THE
POTENTIAL FOR ANY SNOW REACHING DOWN TO VALLEY FLOOR LOCATIONS LOOKS
TO BE LOW. BY THE TIME IT IS COLD ENOUGH...IT APPEARS THAT SHOWER
ACTIVITY WILL BE BASICALLY OVER. BUT IF WE DO MANAGE TO SEE ANY
SHOWERS LATER THIS EVENING...A FEW SPOTS MIGHT SEE SNOW MIXING IN
WITH THE RAIN. THE FCST MODELS ARE INDICATING RAPID CLEARING TONIGHT
FROM NORTH TO SOUTH AS COLD AIR STREAMS IN BEHIND THE UPPER LEVEL
TROUGH AXIS. BASED ON THE CLEARING APPARENT ON VISIBLE SATELLITE
OVER THE OLYMPIC PENINSULA AND ADJACENT COASTAL WATERS...THE MODELS
ARE LIKELY CORRECT ABOUT THIS. THUS THE CURRENT FCST STARTS TO CLEAR
THINGS IN THE NORTHERN TIER OF THE FCST AREA LATE THIS
EVENING...THEN CLEARING OUT DOWN SOUTH OVERNIGHT INTO EARLY TOMORROW
MORNING. THIS SHOULD ALLOW TEMPS TO FALL SIGNIFICANTLY
OVERNIGHT...LEADING TO SOME CONCERN THAT ANY MOISTURE ON ROAD
SURFACE TONIGHT MAY FREEZE AND CREATE SOME SLIPPERY CONDITIONS FOR
TOMORROW MORNING/S COMMUTE. THERE IS ALSO A HIGH LIKELIHOOD THAT
AREAS OF FOG WILL FORM EARLY TOMORROW MORNING AS UPPER LEVEL RIDGING
BEGINS TO BUILD IN ALOFT.
TOMORROW SHOULD PROVIDE A RELATIVELY QUIET DAY AS THE SHORTWAVE UPPER
LEVEL RIDGING IS OVER THE REGION. ANY LOW LEVEL CLOUDS OR FOG SHOULD
DISSIPATE DURING THE DAY...PROVIDING SOME SUN BREAKS FOR MOST. HIGH
CLOUDS MAY BEGIN TO STREAM IN ALOFT LATE TOMORROW AHEAD OF THE NEXT
SYSTEM THAT IS SLATED TO IMPACT US ON FRI.
THE MODEL SOLUTIONS FOR THE FRI SYSTEM CONTINUE TO RAISE CONCERNS OF
A WINTRY MIX AT SOME LOW ELEVATION SITES TO START THE EVENT. THE 12Z
UW WRF-GFS IS INDICATING THAT SOME LIGHT SNOW ACCUMULATIONS ARE
POSSIBLE BEFORE DAY BREAK FRI FOR THE LOWER COLUMBIA BASIN AND I-5
CORRIDOR IN S WA. IT ALSO INDICATES THE POTENTIAL FOR SOME LIGHT SNOW
FALLING INTO THE PORTLAND METRO AREA AROUND THE FRI MORNING COMMUTE.
THE SYSTEM IS FCST TO BRING SOME FAIRLY STRONG SW WINDS AT THE LOW
LEVELS TO SCOUR OUT THE COLD AIR...AND THE COLD POOL LEADING OVER THE
REGION LEADING INTO THE EVENT IS NOT EXPECTED TO BE VERY DEEP. SO THE
CHANCES FOR A HIGH IMPACT EVENT DO NOT APPEAR TO BE VERY GOOD.
HEAVIER RAIN WILL SPREAD OVER THE REGION LATER WED MORNING AND
AFTERNOON...WITH SNOW LEVELS RISING RAPIDLY INTO THE HIGHER CASCADE
TERRAIN. IT APPEARS THAT MOST LOCATIONS WILL GET A SHOT OF MODERATE
RAIN BY FRI NIGHT. PRECIP IS MODELED TO TAPER OFF FRI NIGHT INTO
EARLY SAT...LEAVING JUST A MILDER AND CLOUDY DAY ON SAT IN ONSHORE
FLOW. PYLE
LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...UPPER LEVEL RIDGING
OVER THE EPAC WILL DOMINATE MUCH OF THE EXTENDED FORECAST. THIS WILL
CONTINUE THE NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE PERIOD...AND
PREVENT ANY SUBSTANTIAL SYSTEMS FROM AFFECTING THE AREA. WARM FRONT
ON SUNDAY FOLLOWED BY A DECAYING COLD FRONT ON MONDAY WILL BRING
MOISTURE INTO THE PAC NW FROM TIME TO TIME...HOWEVER THE PRECIP WILL
GENERALLY REMAIN CONFINED TO THE MORE NORTHERN AREAS OF THE CWA. BY
LATE MONDAY THE MODELS DIVERGE...WITH THE ECMWF ALLOWING COLD NORTH
OR NORTHEASTERLY UPPER FLOW TO DEVELOP AS AN UPPER TROUGH DIVES
SOUTH INTO THE GREAT BASIN FROM CANADA. HOWEVER...THE GFS PHASES
THAT LOW WITH A LONGWAVE TROUGH OVER THE MID-WEST...WHICH WOULD
LEAVE THE PACNW UNDER CONTINUED HIGH PRESSURE ALOFT. BURGESS
&&
.AVIATION...06Z TAF PACKAGE. AIR MASS CHANGE CONTINUES BUT AM
FEELING FAR LESS CONVINCED THERE WILL BE WIDESPREAD FOG/STRATUS
ACROSS THE AREA TONIGHT. MODELS INDICATE COLD ADVECTION WILL BRING
CONTINUOUSLY LOWERING DEW POINTS TONIGHT AND THE TEMPERATURE SEEMS
LIKE IT WILL NOT BE ABLE TO QUITE MATCH PACE. AM ONLY MODERATELY
CONFIDENT IN THE APPROACH SO CONTINUED TO HINT AT IMPACTS VIA
REDUCED VSBYS BUT DID MAKE THE LOW CLOUDS SCATTERED. THE EXCEPTION
WILL BE KEUG WHERE THE LOW DECK NEVER LEFT TODAY DESPITE THE SHOWERS
PLUS LIGHT NORTHERLY WINDS WILL PACK MOISTURE TO THE SOUTH END OF
THE WILLAMETTE VALLEY. THEY WILL LIKELY REMAIN UNDER THE FOG/STRATUS
INFLUENCE TOWARD THURSDAY AFTERNOON. BIGGER PROBLEM ACROSS THE AREA
MAY BE WATER ON THE RUNWAYS AND RAMPS TURNING TO ICE AS TEMPERATURES
FALL TO BELOW FREEZING TONIGHT.
KPDX AND APPROACHES...CLOUDS RAPIDLY CLEARING TONIGHT BEHIND THE
FRONT. NO LONGER EXPECT SIGNIFICANT FOG OR STRATUS TO IMPACT THE
FIELD. STILL HINTED AT THE POSSIBILITY BUT FEEL THE MOST LIKELY
SCENARIO WILL KEEP SKIES RELATIVELY CLEAR. DO HAVE CONCERNS FOR
LEFTOVER LIQUID ON THE GROUND TO FREEZE UP ON THE RAMPS AND
RUNWAYS. ICY CONDITIONS MAY HOLD OFF UNTIL JUST BEFORE SUNRISE.
/JBONK
&&
.MARINE...COLD FRONT HAS LARGELY CLEARED THE WATERS AS OF THIS
HOUR. GUSTY NORTHERLY WINDS HAVE INCREASED AS EXPECTED AND SIT
SOLIDLY IN SMALL CRAFT ADVISORY RANGE. THE SWELL HAS BEEN SLOW TO
RISE BUT THE WIND WAVES SEEM TO BE MAKING UP FOR IT AT THIS TIME.
WILL KEEP THE ADVISORIES GOING, IF FOR NOTHING ELSE, AS SEAS
ARE SQUARING UP UNDER THE WIND WAVES AND/OR DEVELOPING FRESH
SWELL.
BRIEF BREAK IN THE ACTION LATER TOMORROW THROUGH FRIDAY MORNING.
A STRONGER SYSTEM BRINGS POTENTIALLY STRONGER GALE FORCE GUSTS AND
SEAS IN THE LOW TEENS FRIDAY AFTERNOON THROUGH EARLY SUNDAY.
/JBONK
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL NOON PST THURSDAY FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON PST THURSDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATED
NWS PORTLAND OR
842 PM PST WED DEC 18 2013
UPDATED AVIATION AND MARINE DISCUSSIONS
.SYNOPSIS..RAIN AND SNOW SHOWERS WILL DIMINISH THROUGH THE EVENING.
CLEARING SKIS WILL DEVELOP FROM NORTH TO SOUTH TONIGHT...LEADING TO
COLDER OVERNIGHT LOWS AND THE POTENTIAL FOR ICY ROAD SURFACES FOR
TOMORROW MORNING. THERE WILL BE A BREAK IN PRECIPITATION TOMORROW
BEFORE A WARMER SYSTEM BRINGS RAIN AND MOUNTAIN SNOW ON FRI. IT
CONTINUES TO LOOK LIKE NORTHERN VALLEY LOCATIONS MAY SEE PRECIP
START AS SNOW FRI MORNING. TEMPS WILL WARM SIGNIFICANTLY LATER
FRI...WITH MODERATE TO HEAVY RAIN EXPECTED OVER MOST OF THE AREA. AN
UPPER LEVEL RIDGE WILL SET UP OVER THE NE PAC LATE IN THE
WEEK...WITH SEVERAL SYSTEMS PUSHING OVER THE TOP OF THE RIDGE
THROUGH EARLY NEXT WEEK.
&&
.UPDATE...HOPEFULLY YOU ARE ALL NOT CONFUSED BY NOW BY OUR
TECHNOLOGICAL CHALLENGES...BUT THE LATEST SPECIAL WEATHER STATEMENT
FOR SLICK ROADS IS FOR TOMORROW MORNINGS COMMUTE...THURSDAY MORNING
AND NOT FRIDAY MORNING.
LATEST GRIDS ARE BEING SENT TO REFLECT LESS IN THE WAY OF FOG
TONIGHT. COLD AIR ADVECTION AND MOISTURE PROFILES DECREASING WITH
HEIGHT IN THE LOWEST LEVELS COUPLES WITH CLEARING SKIES TO SUGGEST
TEMPERATURES IN MOST PLACES WILL BE CHASING DEWPOINTS TONIGHT AND
LIMIT FOG POTENTIAL. OTHERWISE...WET ROADS AND MOST PLACES DIPPING
TO NEAR FREEZING (URBAN AREAS) OR BELOW MEANS THAT THERE WILL LIKELY
BE SOME SLICK OR ICY SPOTS ON ROADWAYS LATE TONIGHT INTO EARLY
FRIDAY.
THERE ARE SOME SHOWERS OUT THERE MOSTLY IN THE FORM OF RAIN...BUT
EXPECT TO SEE SOME SNOWFLAKES MIXED IN AT TIMES EVEN AT THE LOWEST
ELEVATIONS...AS HAS BEEN REPORTED IN ALBANY THIS EVENING. THERE ARE
SOME CONVERGENCE ZONE SHOWERS NORTH OF THE AREA THAT ARE PUSHING
THROUGH LEWIS COUNTY WASHINGTON. LATEST HRRR SUGGESTS THESE DIE OUT
BEFORE GETTING INTO OUR AREA...THOUGH POSSIBLY SOME FLAKES AS WELL
FOR COWLITZ COUNTY.
/KMD
&&
.PREV DISCUSSION... /ISSUED 312 PM PST WED DEC 18 2013/
SHORT TERM...TONIGHT THROUGH SATURDAY... A COLD UPPER LEVEL TROUGH
IS BRINGING INCREASING SHOWERS AND LOWERING SNOW LEVELS ACROSS THE
REGION THIS AFTERNOON. THE BEST SHOWERS ACTIVITY IS CURRENTLY BEING
OBSERVED OVER THE S WA/N OR COAST AND COAST RANGE AND WILLAPA HILLS.
AS THE TROUGH CONTINUES TO PUSH SOUTH THE FOCUS OF THE SHOWER
ACTIVITY WILL BECOME FOCUSED OVER THE N WILLAMETTE VALLEY AND
CENTRAL OR COAST DURING THE LATE AFTERNOON...THEN OVER THE
CENTRAL/SOUTHERN VALLEY THIS EVENING. AS THE COLD AIR MOVES IN
ALOFT...SNOW LEVELS SHOULD FALL DOWN INTO THE COAST RANGE AND
CASCADE FOOTHILLS...BUT ONLY LIGHT ACCUMULATIONS ARE EXPECTED. THE
POTENTIAL FOR ANY SNOW REACHING DOWN TO VALLEY FLOOR LOCATIONS LOOKS
TO BE LOW. BY THE TIME IT IS COLD ENOUGH...IT APPEARS THAT SHOWER
ACTIVITY WILL BE BASICALLY OVER. BUT IF WE DO MANAGE TO SEE ANY
SHOWERS LATER THIS EVENING...A FEW SPOTS MIGHT SEE SNOW MIXING IN
WITH THE RAIN. THE FCST MODELS ARE INDICATING RAPID CLEARING TONIGHT
FROM NORTH TO SOUTH AS COLD AIR STREAMS IN BEHIND THE UPPER LEVEL
TROUGH AXIS. BASED ON THE CLEARING APPARENT ON VISIBLE SATELLITE
OVER THE OLYMPIC PENINSULA AND ADJACENT COASTAL WATERS...THE MODELS
ARE LIKELY CORRECT ABOUT THIS. THUS THE CURRENT FCST STARTS TO CLEAR
THINGS IN THE NORTHERN TIER OF THE FCST AREA LATE THIS
EVENING...THEN CLEARING OUT DOWN SOUTH OVERNIGHT INTO EARLY TOMORROW
MORNING. THIS SHOULD ALLOW TEMPS TO FALL SIGNIFICANTLY
OVERNIGHT...LEADING TO SOME CONCERN THAT ANY MOISTURE ON ROAD
SURFACE TONIGHT MAY FREEZE AND CREATE SOME SLIPPERY CONDITIONS FOR
TOMORROW MORNING/S COMMUTE. THERE IS ALSO A HIGH LIKELIHOOD THAT
AREAS OF FOG WILL FORM EARLY TOMORROW MORNING AS UPPER LEVEL RIDGING
BEGINS TO BUILD IN ALOFT.
TOMORROW SHOULD PROVIDE A RELATIVELY QUIET DAY AS THE SHORTWAVE UPPER
LEVEL RIDGING IS OVER THE REGION. ANY LOW LEVEL CLOUDS OR FOG SHOULD
DISSIPATE DURING THE DAY...PROVIDING SOME SUN BREAKS FOR MOST. HIGH
CLOUDS MAY BEGIN TO STREAM IN ALOFT LATE TOMORROW AHEAD OF THE NEXT
SYSTEM THAT IS SLATED TO IMPACT US ON FRI.
THE MODEL SOLUTIONS FOR THE FRI SYSTEM CONTINUE TO RAISE CONCERNS OF
A WINTRY MIX AT SOME LOW ELEVATION SITES TO START THE EVENT. THE 12Z
UW WRF-GFS IS INDICATING THAT SOME LIGHT SNOW ACCUMULATIONS ARE
POSSIBLE BEFORE DAY BREAK FRI FOR THE LOWER COLUMBIA BASIN AND I-5
CORRIDOR IN S WA. IT ALSO INDICATES THE POTENTIAL FOR SOME LIGHT SNOW
FALLING INTO THE PORTLAND METRO AREA AROUND THE FRI MORNING COMMUTE.
THE SYSTEM IS FCST TO BRING SOME FAIRLY STRONG SW WINDS AT THE LOW
LEVELS TO SCOUR OUT THE COLD AIR...AND THE COLD POOL LEADING OVER THE
REGION LEADING INTO THE EVENT IS NOT EXPECTED TO BE VERY DEEP. SO THE
CHANCES FOR A HIGH IMPACT EVENT DO NOT APPEAR TO BE VERY GOOD.
HEAVIER RAIN WILL SPREAD OVER THE REGION LATER WED MORNING AND
AFTERNOON...WITH SNOW LEVELS RISING RAPIDLY INTO THE HIGHER CASCADE
TERRAIN. IT APPEARS THAT MOST LOCATIONS WILL GET A SHOT OF MODERATE
RAIN BY FRI NIGHT. PRECIP IS MODELED TO TAPER OFF FRI NIGHT INTO
EARLY SAT...LEAVING JUST A MILDER AND CLOUDY DAY ON SAT IN ONSHORE
FLOW. PYLE
LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...UPPER LEVEL RIDGING
OVER THE EPAC WILL DOMINATE MUCH OF THE EXTENDED FORECAST. THIS WILL
CONTINUE THE NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE PERIOD...AND
PREVENT ANY SUBSTANTIAL SYSTEMS FROM AFFECTING THE AREA. WARM FRONT
ON SUNDAY FOLLOWED BY A DECAYING COLD FRONT ON MONDAY WILL BRING
MOISTURE INTO THE PAC NW FROM TIME TO TIME...HOWEVER THE PRECIP WILL
GENERALLY REMAIN CONFINED TO THE MORE NORTHERN AREAS OF THE CWA. BY
LATE MONDAY THE MODELS DIVERGE...WITH THE ECMWF ALLOWING COLD NORTH
OR NORTHEASTERLY UPPER FLOW TO DEVELOP AS AN UPPER TROUGH DIVES
SOUTH INTO THE GREAT BASIN FROM CANADA. HOWEVER...THE GFS PHASES
THAT LOW WITH A LONGWAVE TROUGH OVER THE MID-WEST...WHICH WOULD
LEAVE THE PACNW UNDER CONTINUED HIGH PRESSURE ALOFT. BURGESS &&
.AVIATION...06Z TAF PACKAGE. AIR MASS CHANGE CONTINUES BUT AM
FEELING FAR LESS CONVINCED THERE WILL BE WIDESPREAD FOG/STRATUS
ACROSS THE AREA TONIGHT. MODELS INDICATE COLD ADVECTION WILL BRING
CONTINUOUSLY LOWERING DEW POINTS TONIGHT AND THE TEMPERATURE SEEMS
LIKE IT WILL NOT BE ABLE TO QUITE MATCH PACE. AM ONLY MODERATELY
CONFIDENT IN THE APPROACH SO CONTINUED TO HINT AT IMPACTS VIA
REDUCED VSBYS BUT DID MAKE THE LOW CLOUDS SCATTERED. THE EXCEPTION
WILL BE KEUG WHERE THE LOW DECK NEVER LEFT TODAY DESPITE THE SHOWERS
PLUS LIGHT NORTHERLY WINDS WILL PACK MOISTURE TO THE SOUTH END OF
THE WILLAMETTE VALLEY. THEY WILL LIKELY REMAIN UNDER THE FOG/STRATUS
INFLUENCE TOWARD THURSDAY AFTERNOON. BIGGER PROBLEM ACROSS THE AREA
MAY BE WATER ON THE RUNWAYS AND RAMPS TURNING TO ICE AS TEMPERATURES
FALL TO BELOW FREEZING TONIGHT.
KPDX AND APPROACHES...CLOUDS RAPIDLY CLEARING TONIGHT BEHIND THE
FRONT. NO LONGER EXPECT SIGNIFICANT FOG OR STRATUS TO IMPACT THE
FIELD. STILL HINTED AT THE POSSIBILITY BUT FEEL THE MOST LIKELY
SCENARIO WILL KEEP SKIES RELATIVELY CLEAR. DO HAVE CONCERNS FOR
LEFTOVER LIQUID ON THE GROUND TO FREEZE UP ON THE RAMPS AND
RUNWAYS. ICY CONDITIONS MAY HOLD OFF UNTIL JUST BEFORE SUNRISE.
/JBONK
&&
.MARINE...COLD FRONT HAS LARGELY CLEARED THE WATERS AS OF THIS
HOUR. GUSTY NORTHERLY WINDS HAVE INCREASED AS EXPECTED AND SIT
SOLIDLY IN SMALL CRAFT ADVISORY RANGE. THE SWELL HAS BEEN SLOW TO
RISE BUT THE WIND WAVES SEEM TO BE MAKING UP FOR IT AT THIS TIME.
WILL KEEP THE ADVISORIES GOING, IF FOR NOTHING ELSE, AS SEAS
ARE SQUARING UP UNDER THE WIND WAVES AND/OR DEVELOPING FRESH
SWELL.
BRIEF BREAK IN THE ACTION LATER TOMORROW THROUGH FRIDAY MORNING.
A STRONGER SYSTEM BRINGS POTENTIALLY STRONGER GALE FORCE GUSTS AND
SEAS IN THE LOW TEENS FRIDAY AFTERNOON THROUGH EARLY SUNDAY.
/JBONK
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL NOON PST THURSDAY FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON PST THURSDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1141 AM CST THU DEC 19 2013
.UPDATE...
18Z AVIATION DISCUSSION UPDATED BELOW.
WITH LAST NIGHTS 6Z AND THE NEW 12Z MODELS ZEROING IN ON MY CWA
FOR THE BAND OF SNOW...HAVE DECIDED TO EXPAND THE ADVISORY EAST TO
ENCOMPASS THE ENTIRE CWA. SNOWFALL AMOUNTS OF 2 TO 5 INCHES CAN BE
EXPECTED WITH HIGH SNOW TO LIQUID RATIOS. LUCKILY WINDS WONT BE
TOO BAD BUT STILL BREEZY WHICH COULD LEAD TO SOME BLOWING AND
DRIFTING. WIND CHILLS WILL ALSO BE BOUNCING UP AGAINST CRITERIA BUT
FOR NOW WILL LET THIS BAND OF SNOW GET THROUGH BEFORE WORRYING TOO
MUCH ABOUT WIND CHILLS. UPDATES ALREADY ISSUED.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A STORM SYSTEM MOVING ACROSS THE REGION WILL BRING LIGHT SNOW AND
NORTHERLY WINDS OF 10 TO 20 KNOTS. THE COMBINATION OF FALLING SNOW
AND THE WINDS WILL CAUSE REDUCTION IN VISIBILITIES TO 3/4SM OR
LESS AT TIMES. CEILINGS WILL ALSO LOWER TO IFR/MVFR RANGE AS WELL.
EXPECT THE LIGHT SNOW TO DIMINISH INTO THE EVENING HOURS AND END
OVERNIGHT WITH CEILINGS INCREASING TO LOW END VFR. WINDS WILL ALSO
DECREASE THROUGH THE NIGHT.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 9 PM CST /8 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BROWN-CLARK-
CODINGTON-DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS-SPINK.
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BIG STONE-
TRAVERSE.
&&
$$
UPDATE...TDK
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...SD
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
937 AM CST THU DEC 19 2013
.UPDATE...
WITH LAST NIGHTS 6Z AND THE NEW 12Z MODELS ZEROING IN ON MY CWA
FOR THE BAND OF SNOW...HAVE DECIDED TO EXPAND THE ADVISORY EAST TO
ENCOMPASS THE ENTIRE CWA. SNOWFALL AMOUNTS OF 2 TO 5 INCHES CAN BE
EXPECTED WITH HIGH SNOW TO LIQUID RATIOS. LUCKILY WINDS WONT BE
TOO BAD BUT STILL BREEZY WHICH COULD LEAD TO SOME BLOWING AND
DRIFTING. WIND CHILLS WILL ALSO BE BOUNCING UP AGAINST CRITERIA BUT
FOR NOW WILL LET THIS BAND OF SNOW GET THROUGH BEFORE WORRYING TOO
MUCH ABOUT WIND CHILLS. UPDATES ALREADY ISSUED.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
CEILINGS WILL FALL AND LIGHT SNOW WILL DEVELOP AT ALL TERMINALS
TODAY AS UPPER LEVEL DIVERGENCE SPREADS OVER THE REGION. THE
CEILINGS AND VISIBILITIES WILL FALL TO IFR/MVFR AS THE LIGHT SNOW
DEVELOPS THROUGHOUT THE MORNING AND AFTERNOON. VISIBILITIES COULD
FALL TO 3/4SM OR LESS AT TIMES. ALSO...WITH BLUSTERY NORTH TO
NORTHEAST WINDS SOME BLOWING SNOW IS EXPECTED. EXPECT THE LIGHT
SNOW TO DIMINISH INTO THE EVENING HOURS AND END OVERNIGHT WITH
CEILINGS REMAINING MVFR ALONG WITH DECREASING WINDS.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 9 PM CST /8 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BROWN-CLARK-
CODINGTON-DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS-SPINK.
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BIG STONE-
TRAVERSE.
&&
$$
UPDATE...TDK
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
603 AM CST THU DEC 19 2013
.UPDATE...
12Z AVIATION DISCUSSION UPDATED BELOW.
&&
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
CEILINGS WILL FALL AND LIGHT SNOW WILL DEVELOP AT ALL TERMINALS
TODAY AS UPPER LEVEL DIVERGENCE SPREADS OVER THE REGION. THE
CEILINGS AND VISIBILITIES WILL FALL TO IFR/MVFR AS THE LIGHT SNOW
DEVELOPS THROUGHOUT THE MORNING AND AFTERNOON. VISIBILITIES COULD
FALL TO 3/4SM OR LESS AT TIMES. ALSO...WITH BLUSTERY NORTH TO
NORTHEAST WINDS SOME BLOWING SNOW IS EXPECTED. EXPECT THE LIGHT
SNOW TO DIMINISH INTO THE EVENING HOURS AND END OVERNIGHT WITH
CEILINGS REMAINING MVFR ALONG WITH DECREASING WINDS.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 7 PM CST /6 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
MN...NONE.
&&
$$
UPDATE...MOHR
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
348 AM CST THU DEC 19 2013
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
MVFR CIGS WILL SPREAD OVER THE AREA THROUGH THE OVERNIGHT
HOURS...WITH THE POSSIBILITY OF CIGS DROPPING INTO THE IFR
CATEGORY AT TIMES. WIDESPREAD LIGHT SNOW WILL SPREAD FROM WEST TO
EAST DURING THE AFTERNOON HOURS ON THURSDAY...WITH MAINLY MVFR
VSBYS EXPECTED.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 7 PM CST /6 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
MN...NONE.
&&
$$
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
948 PM CST FRI DEC 20 2013
.UPDATE...
THE LATEST WATER VAPOR LOOP SHOWS THE UPPER LOW CENTER TRUDGING
EAST AND GETTING CLOSER TO WEST TEXAS. LIFT IS ON THE INCREASE
ACROSS NORTH AND CENTRAL TEXAS...AND PRECIPITATION COVERAGE IS EXPECTED
TO RAMP UP OVER THE NEXT FEW HOURS. ISOLATED CONVECTION HAS BEGUN
IN THE WARM SECTOR WITH A FEW LIGHTNING STRIKES SHOWING UP NEAR
CANTON. MEANWHILE...THE SHALLOW ARCTIC AIRMASS HAS BARRELED
FARTHER SOUTH INTO CENTRAL TEXAS AND THE 32 DEGREE ISOTHERM HAD
DROPPED SOUTH OF POSSUM KINGDOM DURING THE PAST HOUR. WILL ADJUST
LOWS DOWNWARD ACCORDINGLY...WHILE ADDING A FEW MORE COUNTIES TO THE
RAIN/FREEZING RAIN MIX AREA WEST AND NORTHWEST OF THE DALLAS-FORT
WORTH METROPLEX...WITH LITTLE OR NO ACCUMULATIONS STILL EXPECTED.
30
&&
.AVIATION...
IFR CONDITIONS WILL PREVAIL THROUGH AT LEAST 18Z SATURDAY WITH
SOME IMPROVEMENT TO MVFR BY MID AFTERNOON /21Z/. A COLD FRONT HAD
MOVED TO SOUTH OF A KSLR /SULPHUR SPRINGS/...KACT /WACO...KBBD
/BRADY/ LINE AS OF 00Z. THIS FRONT IS EXPECTED TO STALL SLIGHTLY
SOUTH OF THIS LOCATION LATER TONIGHT. UPPER LEVEL LOW OVER
SOUTHEASTERN ARIZONA WILL MOVE INTO FAR WEST TEXAS BY DAYBREAK
SATURDAY /12Z/ AND THEN MOVE NORTHEAST INTO NORTHWESTERN OKLAHOMA
BY SUNSET SATURDAY /00Z SUNDAY/. LIFT FROM THIS SYSTEM ALONG WITH
WARM MOIST AIR OVERRUNNING A SHALLOW COLD FRONT WILL RESULT IN
WIDESPREAD RAIN AND LOW CEILINGS THROUGH MOST OF SATURDAY
AFTERNOON. THE RAIN SHOULD COME TO AN END AND CEILINGS ARE
EXPECTED TO IMPROVE BY LATE SATURDAY AFTERNOON WITH VFR
CONDITIONS EXPECTED AFTER 00Z SUNDAY.
58
&&
.PREV UPDATE...
.UPDATE...
WILL GO AHEAD AND ADD SOME FREEZING RAIN TO THE FAR NORTHWESTERN
PORTIONS OF NORTH TEXAS...ROUGHLY ALONG AND NORTH OF A GAINESVILLE
TO GRAHAM LINE. TEMPERATURES ARE HOVERING AT 32 TO 33 DEGREES IN
THESE LOCATIONS AND WE DO NOT EXPECT ANY ACCUMULATIONS ON THE
GROUND. SOME ELEVATED SURFACES SUCH AS CARS...TABLES...TREES
ETC. MAY SEE SOME MINOR ACCUMULATIONS. TEMPERATURES MAY ACTUALLY WARM
A DEGREE OR TWO AFTER MIDNIGHT AS PRECIPITATION INTENSITY INCREASES
AND SOME OF THE 50+ DEGREE AIR WITHIN THE WARM NOSE ALOFT MIXES
DOWN.
ELSEWHERE...WE ARE STILL EXPECTING THE HEAVIEST RAINFALL
OVERNIGHT THROUGH SATURDAY MORNING AND NO OTHER CHANGES ARE
PLANNED AT THIS TIME.
30
&&
.PREV DISCUSSION... /ISSUED 411 PM CST FRI DEC 20 2013/
21Z SUBJECTIVE SURFACE ANALYSIS SHOWED A STRONG COLD FRONT IN
PLACE ALONG A LINE FROM PARIS TO DALLAS TO HAMILTON. THE
TEMPERATURE GRADIENT ALONG THIS BOUNDARY WAS QUITE IMPRESSIVE WITH
A 70 DEGREE TEMPERATURE THAT WAS OBSERVED AT GREENVILLE...A 49
DEGREE TEMPERATURE AT MCKINNEY AND A 39 DEGREE TEMPERATURE AT
DENTON. THIS FRONT WAS STILL MOVING SOUTHEAST AT 15 MPH AT THE
TIME OF THIS DISCUSSION. A 20Z AIRPLANE SOUNDING FROM DALLAS LOVE
FIELD INDICATED THAT THE FRONT WAS SHALLOW IN NATURE...WITH THE
FRONTAL INVERSION ONLY EXTENDING UP ABOUT 1500 FEET ABOVE GROUND
LEVEL. THE FRONT IS STILL EXPECTED TO STALL OUT OVER THE FAR
SOUTHEASTERN CWA THIS EVENING...IN RESPONSE TO CYCLOGENESIS
INITIATED BY THE APPROACH OF A POWERFUL UPPER LEVEL STORM SYSTEM.
THIS UPPER LEVEL STORM SYSTEM WAS OBSERVED OVER BAJA CALIFORNIA AT
20Z BASED ON WATER VAPOR SATELLITE IMAGERY. OUT AHEAD OF THIS
UPPER LEVEL STORM SYSTEM...WATER VAPOR SATELLITE IMAGERY SHOWED A
NICE CONTINUOUS BAND OF SUB-TROPICAL PACIFIC MOISTURE STREAMING
NORTHEAST OVER NORTHERN MEXICO AND THE SOUTH PLAINS. THE HIGH
TERRAIN OF NORTHERN MEXICO WILL SCOUR OUT ALL OF THE LOW TO MID-
TROPOSPHERIC MOISTURE ASSOCIATED WITH THIS SUBTROPICAL PLUME...BUT
THE MID TO UPPER LEVEL MOISTURE WILL CONTRIBUTE TO MOISTURE DEPTH
OVER THE REGION AS THE UPPER LEVEL STORM SYSTEM MOVES ACROSS THE
AREA TONIGHT INTO TOMORROW MORNING.
THROUGH TONIGHT...THE MOST TROUBLESOME FORECAST PROBLEM IN THE
SHORT TERM FORECAST IS THAT ALL FORECAST GUIDANCE IS DOING A
REMARKABLY POOR JOB RESOLVING THE STRENGTH OF THE SHALLOW COLD AIR
ASSOCIATED WITH/BEHIND THE COLD FRONT. WHILE ALL GUIDANCE IS DOING
A POOR JOB RESOLVING SURFACE TEMPERATURES NORTH OF THE COLD
FRONT...THE RAP IN PARTICULAR IS DIFFICULT TO PROCESS BECAUSE IT
CONTINUES TO INITIALIZE THE COLD AIR...BUT PERSISTENTLY BRINGS
SURFACE TEMPERATURES UP 5-7 DEGREES AT FORECAST HOUR 1 DESPITE
PERSISTENT COLD AIR ADVECTION AND CLOUD COVER. THIS WOULD BE MORE
OR LESS A NUISANCE IF THE TEMPERATURES HAD NO POTENTIAL TO HAVE AN
IMPACT ON PRECIPITATION TYPE IN THIS FORECAST. FOR INSTANCE...AT
BOWIE...THE 21Z OBSERVATION HAD A TEMPERATURE OF 32 DEG F. THE RAP
INITIALIZES THIS AT 34 DEGREES...WHICH IS NOT TOO FAR OFF...BUT
THEN GOES AHEAD TO FORECAST A TEMPERATURE OF 40 DEGREES BY 22Z.
WITH WIDESPREAD RAINFALL DEVELOPING OVER THE REGION RIGHT
NOW...AND EXPECTED TO PERSIST THIS EVENING INTO THE OVERNIGHT
HOURS...THIS ERROR IN RESOLVING NEAR SURFACE TEMPERATURES IS QUITE
PROBLEMATIC. THEREFORE...AT THIS TIME...WITH NO GUIDANCE AVAILABLE
ACTUALLY RESOLVING THE STRENGTH OF THIS COLD AIR...THE
PRECIPITATION TYPE FORECAST FOR TONIGHT WAS COMPLETED USING
OBSERVATIONAL TRENDS...RECENT FORECAST EVENTS AND INTUITION.
AT THIS TIME EXPECT THAT TEMPERATURES ALONG AND NORTHWEST OF A
GAINESVILLE TO GRAHAM LINE ARE MOST LIKELY TO FALL TO 32 DEGREES
THIS EVENING...LIKELY HOLDING STEADY THROUGH MUCH OF THE OVERNIGHT
HOURS. AS A RESULT...EVEN IF WE SEE RAIN AT 31 TO 32 DEGREES FOR
SEVERAL HOURS...THE CURRENT THINKING IS THAT WE WILL NOT SEE ANY
ICE ACCUMULATION...EXCEPT PERHAPS ON TREE TOPS OR THE TOPS OF
EXPOSED METAL SURFACES. THE REASONS FOR THIS ARE AS FOLLOWS:
1. BEFORE THE FRONT...WE HAVE EXPERIENCED A FEW DAYS OF ABOVE
NORMAL TEMPERATURES. GROUND/ROAD TEMPERATURES ARE WELL ABOVE
FREEZING WHICH WILL NOT ALLOW FOR ICE ACCUMULATION.
2. THE DEPTH OF THE ELEVATED WARM LAYER IS ALMOST 8 TIMES AS DEEP
AS THE DEPTH OF THE COLD/SUB-FREEZING LAYER. RAIN FALLING IN THIS
ENVIRONMENT WILL LIKELY HAVE A TEMPERATURE ABOVE FREEZING WHEN IT
REACHES THE SURFACE. THAT IS THE TEMPERATURE OF THE FALLING RAIN
DROPS ARE LIKELY TO BE ABOVE FREEZING...THIS IS ALSO NOT CONDUCIVE
TO ICE ACCUMULATION.
3. ALL GUIDANCE INDICATES PERSISTENT WARM AIR ADVECTION THROUGH
12Z SATURDAY ABOVE THE COLD FRONTAL INVERSION. THE WARM LAYER IS
VERY LIKELY TO MAINTAIN ITS DEPTH AND STRENGTH...WHILE RELATIVELY
WARM RAIN DROPS MAY ACTUALLY SHRINK THE DEPTH OF THE SHALLOW COLD
AIR OVERNIGHT.
AS A RESULT...WILL NOT BE HIGHLIGHTING FREEZING RAIN IN THE
FORECAST AT THIS TIME...DESPITE THE SURFACE OBSERVATION AT BOWIE
AT 32 DEGREES SEEMINGLY SHOWING AN ICE STORM ON OUR DOORSTEP. IT
LOOKS LIKE THE DEPTH OF THE COLD AIR WILL ONLY SUPPORT ICE
ACCUMULATION FARTHER NORTH...WELL INTO OKLAHOMA BASED ON
OBSERVATIONAL ANALYSIS AND DFW AREA AIRCRAFT SOUNDINGS.
DESPITE ALL THAT HAS BEEN DISCUSSED ABOUT THE SHALLOW COLD AIR
PROBLEM...THERE WERE ACTUALLY NO SIGNIFICANT CHANGES MADE TO THE
PREVIOUS FORECAST WHICH REMAINS LARGELY ON TRACK. THE BAJA UPPER
LEVEL LOW IS STILL EXPECTED TO MOVE OVER THE SOUTH PLAINS TOMORROW
MORNING...SPREADING STRONG LARGE SCALE FORCING FOR ASCENT OVER THE
REGION TONIGHT THROUGH TOMORROW MORNING. NEARLY ALL GUIDANCE
INDICATES THAT THE UPPER LOW WILL BECOME INCREASINGLY NEGATIVELY
TILTED AS IT MOVES OUT OVER TEXAS...DEEPENING AS IT MOVES OVER THE
CWA. THE STRONGEST FORCING FOR ASCENT LOOKS TO MOVE OVER THE CWA
IN THE 09 TO 15Z TIME FRAME...WHICH SHOULD ALSO REPRESENT OUR
WINDOW FOR THE BEST COVERAGE AND HEAVIEST PRECIPITATION RATES
DURING THIS EVENT.
FOR THIS EVENING...THE COLD FRONT PUSHING SOUTH THROUGH MOST OF
THE CWA WILL SIMPLY HELP TO STEEPEN LOW-LEVEL ISENTROPIC SURFACES
AS CYCLOGENESIS RAMPS UP NEAR DEL RIO RESULTING IN AN INCREASE OF
THE STRENGTH OF THE LOW TO MID-LEVEL WIND FIELD. THIS SHOULD
RESULT IN A SPREAD OF THE COVERAGE OF ONGOING RAIN SHOWER
ACTIVITY FROM WEST TO EAST ACROSS THE CWA. AS THE UPPER LEVEL LOW
APPROACHES...ASSUMING IT BECOMES MORE NEGATIVELY TILTED AS
ADVERTISED...WE SHOULD SEE AN ENHANCEMENT OF MID-LEVEL LAPSE RATES
WITH SOME UPPER-LEVEL COLD AIR ADVECTION OVER THE PERSISTENT LOW-
LEVEL WARM AIR ADVECTION REGIME. THIS WILL RESULT IN AN INCREASED
CHANCE OF ISOLATED THUNDERSTORMS EMBEDDED IN THE RAIN SHOWER
ACTIVITY FROM SUNSET TO MIDNIGHT. ALL OF THIS ACTIVITY SHOULD
REMAIN ELEVATED IN NATURE...AND POSES VERY LITTLE SEVERE WEATHER
THREAT AS A RESULT. RAINFALL RATES WILL BE ENHANCED...AND
THEREFORE SOME LOCALIZED HEAVY RAINFALL IS POSSIBLE.
AFTER MIDNIGHT...AS MENTIONED ABOVE...THE BEST LARGE SCALE FORCING
FOR ASCENT IS EXPECTED TO BUILD ACROSS THE CWA FROM WEST TO EAST
DURING THIS TIME RESULTING IN THE STRONGEST AND MOST WIDESPREAD
CONVECTION AND PRECIPITATION FOR THE REGION. BASED ON THE POSITION
OF THE COLD FRONT AT THAT TIME...WE DO HAVE A WINDOW FOR SURFACE
BASED SEVERE STORMS BASED ON CONVECTIVE PARAMETERS ADVERTISED IN
THE MAJORITY OF GUIDANCE. LOCATIONS ALONG AND SOUTHEAST OF
WHEREVER THE COLD FRONT STALLS OUT WOULD BE THE ONLY LOCATIONS
WHERE SURFACE BASED SEVERE STORMS WOULD BE POSSIBLE. FORECAST
CONVECTIVE PARAMETERS INDICATED SURFACE BASED CAPE VALUES OF
AROUND 1000 J/KG WITH 0-3 KM CAPE VALUES OF AROUND 100 J/KG AND
DEEP LAYER SHEAR VALUES IN EXCESS OF 50 KTS.
THESE VALUES ARE SUPPORTIVE OF A LOW-TOPPED SUPER CELLULAR STORM
MODE...WHICH COULD RESULT IN LARGE HAIL...DAMAGING WIND OR
ISOLATED TORNADOES. THIS THREAT IS MODERATED BY STRONG FORCING
WHICH MAY MAKE AN ISOLATED STORM MODE DIFFICULT TO REALIZE...AND
STRONG CLOUD LEVEL WINDS THAT WILL LIKELY TAKE STORMS THAT DEVELOP
ALONG THE FRONT...OVER/NORTH OF THE FRONT SHORTLY AFTER
INITIATION. REGARDLESS...WILL BE WATCHING FOR WHERE THE FRONT
STALLS OUT TONIGHT AS LOCATIONS NEAR AND TO THE SOUTHEAST OF THE
BOUNDARY ARE THE MOST LIKELY TO SEE SEVERE WEATHER. FURTHER
NORTHWEST...STRONG STORMS REMAIN POSSIBLE...HOWEVER EVEN ELEVATED
SUPERCELLS ARE ONLY GOING TO PROVIDE A THREAT FOR MARGINALLY
SEVERE HAIL...SO THE OVERALL SEVERE WEATHER THREAT NORTHWEST OF
THE FRONT DIMINISHES GREATLY.
FOR ANYWHERE ACROSS NORTH TEXAS...LOCALLY HEAVY RAINFALL IS
POSSIBLE WHICH MAY RESULT IN SOME LOCALIZED FLASH FLOODING ISSUES
OVER THE NEXT 24 HRS. WITH THE SUB-TROPICAL PACIFIC MOISTURE FEED
IN PLACE...AND LOW-LEVEL WARM MOIST ADVECTION EXPECTED TO RAMP UP
IN INTENSITY OVER THE SHALLOW COLD FRONT...NEARLY ALL GUIDANCE
INDICATES THAT PWAT VALUES WILL BE UP AROUND 1.5 INCHES ACROSS
NORTH AND CENTRAL TEXAS AS THE UPPER LOW SPREADS STRONG FORCING
OVER THE REGION. 1.5 INCH PRECIPITABLE WATER VALUES RANK AS PLUS 3
STANDARD DEVIATION FOR NORTH TEXAS AT THIS TIME OF YEAR. THIS
EXCEPTIONALLY DEEP MOISTURE COMBINED WITH FAVORABLE DYNAMICS FOR
WIDESPREAD PRECIPITATION SUPPORT A LOCALIZED HEAVY RAINFALL THREAT
WITH AN ATTENDANT LOCALIZED FLOODING THREAT TONIGHT INTO TOMORROW
MORNING. DID NOT ISSUE A FLASH FLOOD WATCH AT THIS TIME BECAUSE
OUR PRIMARY WINDOW FOR HEAVY RAINFALL IS ONLY EXPECTED TO BE ON
THE ORDER OF 6 HOURS OR SO. IF STRONG FORCING WAS EXPECTED TO BE
IN PLACE FOR A LONGER PERIOD OF TIME...THE THREAT OF WIDESPREAD
FLOODING WOULD BE MUCH GREATER AND A WATCH WOULD HAVE BEEN ISSUED.
AT THIS TIME THE THREAT OF FLOODING IS EXPECTED TO REMAIN
LOCALIZED AND MAINLY CONFINED TO LOW LYING/COMMONLY FLOODED AREAS.
HEAVY PRECIPITATION IS EXPECTED TO COME TO AN END FROM SOUTHWEST
TO NORTHEAST SATURDAY AFTERNOON AS A STRONG MID-LEVEL DRY SLOT
PUNCHES OVER THE REGION. LIGHT RAIN MAY PERSIST ACROSS THE AREA
SATURDAY AFTERNOON...BUT EVEN THIS WILL BE SCOURED OUT BY SUNSET.
REMAINDER OF THE FORECAST...NO SIGNIFICANT CHANGES WERE MADE TO
THE PREVIOUS FORECAST AS MOST OF THE ACTIVITY IN THE FORECAST IS
IN THE FIRST 24 HOURS. HIGHLIGHTS OF THE REMAINDER OF THE FORECAST
INCLUDE:
1. ADDED A MENTION OF SPRINKLES/LIGHT RAIN TO THE FORECAST ALONG
THE COLD FRONT THAT IS EXPECTED TO PUSH SOUTH THROUGH THE CWA ON
SUNDAY MORNING. WILL HAVE TO WATCH TEMPERATURES CLOSELY SUNDAY
MORNING AS THIS FRONT ROLLS THROUGH...HOWEVER ALL GUIDANCE
INDICATES TEMPERATURES JUST ABOVE FREEZING WITH THIS VERY LIGHT
PRECIPITATION.
2. WE SHOULD BE DRY EARLY NEXT WEEK...LEADING UP TO CHRISTMAS DAY.
TEMPERATURES WILL SLOWLY WARM THROUGH CHRISTMAS...ALTHOUGH HIGHS
ARE EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEK AHEAD.
3. AN UPPER LEVEL STORM SYSTEM MAY RESULT IN SCATTERED RAIN
SHOWERS ACROSS THE REGION ON CHRISTMAS DAY. AT THIS TIME
TEMPERATURES ARE EXPECTED TO BE WELL ABOVE FREEZING...SO NO
SIGNIFICANT IMPACTS ARE EXPECTED AT THIS TIME.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 36 47 36 48 29 / 100 100 10 10 5
WACO, TX 42 62 37 50 30 / 80 100 10 10 5
PARIS, TX 41 45 36 47 26 / 100 100 10 10 10
DENTON, TX 33 44 34 47 26 / 100 100 10 10 5
MCKINNEY, TX 35 44 35 46 25 / 100 100 10 10 5
DALLAS, TX 37 46 38 48 30 / 100 100 10 10 5
TERRELL, TX 41 47 37 47 28 / 100 100 10 10 5
CORSICANA, TX 46 54 39 48 30 / 80 100 10 10 5
TEMPLE, TX 41 63 39 52 31 / 80 100 10 10 5
MINERAL WELLS, TX 32 49 34 48 24 / 100 90 10 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
910 PM CST FRI DEC 20 2013
.UPDATE...
THE ONLY CHANGE ON THIS SHIFT WAS TO ADJUST SHORT TERM POPS/WX TO
BETTER COME IN-LINE WITH ONGOING TRENDS. DURING THE 8 PM HOUR...THE
COLD FRONT IS WORKING ITS WAY SOUTHWARD AND NOW PUSHING INTO THE
SOUTHERN COUNTIES OF DFW`S CWA. DOWNSTREAM OF THIS MAIN BOUNDARY...
VERY LIGHT RAIN SHOWERS OR DRIZZLE AFFECTING OUR FA...MOVING NORTH
WITHIN A VERY PERSISTENT SWATH OF 40 KT JUST-OFF-THE-SURFACE SOUTHERLY
(LLJ) FLOW. A VERY WARM AND MOIST OVERNIGHT WITH SEA FOG LOWERING
MARITIME VISIBILITIES TO UNDER A COUPLE OF MILES AT TIMES...LOCALLY
DENSE AT A MILE OR UNDER ESPECIALLY IF NEARSHORE SOUTHERLIES BACK
A BIT MORE EASTERLY WITH TIME. MINIMUM TEMPERATURES WILL BE A
DEGREE OR TWO OFF 70 F...WITH SIGNIFICANTLY GREATER CONVECTIVE
CHANCES FROM AROUND 21/09Z ONWARD OVER THE NORTHERN FORECAST
AREA. THE HRRR DISPLAYING THE FORMATION OF MORE DISCRETE CELLS
FROM SHORTLY AFTER MIDNIGHT THROUGH SUNRISE. OUR MOISTENED DOWNSTREAM
ENVIRONMENT (AROUND AN INCH PWAT) IS HIGHLY SHEARED AFFORDING HIGH
HELICITY AND SIGNALING THAT MANY UPDRAFTS WILL ROTATE. SPC HAS THE
NORTHERN THIRD OF THE CWA HIGHLIGHTED IN SLIGHT RISK TO ACCOUNT
FOR THIS EARLY MORNING THROUGH EARLY AFTERNOON THREAT FOR STRONG
CELLS...POSSIBLY WITHIN A BROKEN WEST-MOVING-EAST QLCS...REACHING
SEVERE LIMITS. DAMAGING WINDS AND TORNADOES WILL BE THE MAIN THREATS
THROUGH MID-SATURDAY. 31
&&
.PREV DISCUSSION... /ISSUED 554 PM CST FRI DEC 20 2013/
DISCUSSION...
UPDATED AVIATION FOR OOZ TAFS.
AVIATION...
TRICKY FORECAST WITH CEILING HEIGHTS OVERNIGHT...AND TIMING OF THE
THUNDERSTORM THREAT BEING THE BIGGEST CHALLENGES. ALREADY SEEING
CIGS IN THE 1000 TO 1200 FOOT RANGE SOME LOCATIONS. GLS SOCKED IN
WITH SEA FOG AND HALF MILE VISIBILITY. RADAR SHOWING LIGHT RETURNS
INCREASING ASSOCIATED WITH VERY LIGHT SHOWERS OR SPRINKLES.
OVERNIGHT AM IN GENERAL GOING WITH MVFR CIGS PREVAILING...NEAR
CURRENT LEVELS BUT THINK THERE WILL BE A WINDOW OF CIGS BLO 1000
FEET AT MOST AIRPORTS AND HAVE INDICATED THAT WITH A TEMPO GROUP
OVERNIGHT MOST SITES. THUNDERSTORM THREAT WILL BE SATURDAY MORNING
FOR CLL AND UTS...MORE MIDDAY AND EARLY AFTERNOON FOR CXO AND IAH
AND AFTERNOON FOR HOU...SGR...LBX AND GLS. MOST LIKELY SCENARIO
WILL BE NUMEROUS LIGHT SHOWERS UNDERNEATH THE CAP BEFORE
THEN...THEN THE DEVLOPMENT OF A LINE OF STORMS THAT WILL MOVE
QUICKLY OVER THE AREA. THREAT SHOULD BE EAST OF THE TAF SITES BY
LATE TOMORROW AFTERNOON. 46
&&
PREV DISCUSSION... /ISSUED 406 PM CST FRI DEC 20 2013/
.SLIGHT RISK OF SEVERE WEATHER TONIGHT INTO SATURDAY...
DISCUSSION...
SFC ANALYSIS HAS COLD FRONT PUSHING THROUGH DFW METROPLEX HEADED
TOWARDS A TYLER/WACO LINE. FRONT SHOULD PUSH CLOSE TO A COLLEGE
STATION TO CROCKETT LINE TONIGHT BUT LIKELY STALL JUST NORTH.
MOISTURE HAS DEEPENED WITH SFC DEWPOINTS IN THE 70S. SEA FOG MAY
BE AN ISSUE ALONG THE COAST SO WILL HAVE ANOTHER DENSE FOG
ADVISORY FOR THE COAST TONIGHT. SHOWERS SHOULD INCREASE OVERNIGHT
WITHIN MAY MOISTURE AXIS THROUGH THE AREA. SO REALLY NO CHANGES IN
THE FORECAST THROUGH TONIGHT.
UPPER AIR ANALYSIS AND WATER VAPOR IMAGERY SHOW STRONG UPPER LOW
MOVING ACROSS NORTHERN MEXICO AND S ARIZONA. UPPER LOW SHOULD
REACH EL PASO AND BIG BEND AREA BY 12Z SAT WITH HEIGHT FALLS OVER
TX AND LARGE SCALE ASCENT SPREADING INTO THE AREA.
THIS SHOULD SUPPORT THUNDERSTORM ACTIVITY ALONG THE FRONTAL
BOUNDARY TONIGHT WHICH MAY STALL JUST NORTH OF COLLEGE STATION.
SPC HIGHLIGHTS SMALL SEVERE WEATHER PROBS FOR THIS SCENARIO. AS
THE UPPER LOW MOVES EAST...EXPECT ANOTHER LINE OF STORMS TO FORM
ALONG APPROACHING PACIFIC FRONT WHICH SHOULD PUSH INTO THE ARE
DURING THE MORNING. THE 12Z TX TECH WRF AND 4KM WRF-ARW SHOW THIS
LINE DEVELOPING IN THE PRE-DAWN HOURS AND MOVING INTO THE AREA.
BASICALLY LEFT 60/70 POPS FOR OVERNIGHT TIME FRAME TO ACCOUNT FOR
THIS POSSIBILITY BUT FEEL MOST THUNDERSTORM ACTIVITY WILL BE
DURING THE DAY SATURDAY.
SATURDAY WILL BE MORE SPRING LIKE WITH REGARDS TO THUNDERSTORM
ACTIVITY THAN THE FIRST DAY OF WINTER. MODELS ARE ALL ON THE SAME
PAGE WITH HOW THE UPPER LOW MOVES TOWARDS C/NE OK BY 00Z SUN. MAIN
CONCERN WILL BE WHETHER STRONG MID LEVEL CAP WILL ERODE. 850MB
TEMPS LOOK TO WARM NEAR 16-20C ON THE GFS BY 18Z SAT. THE NAM
ERODES THE CAP QUITE A BIT DURING THIS TIME. THE PROBLEM IS THAT
NONE OF THE MODELS REALLY BRING GOOD PVA OVER THE AREA AND KEEP IT
NORTH OF THE AREA. OMEGA FIELDS SUPPORT BREAKING THE CAP BUT HAVE
SEEN SEVERAL TIMES BEFORE WHERE THE CAP HOLDS PRETTY STRONG. MAIN
QUESTION WILL BE WHEN EXACTLY THE CAP WILL BREAK. IF THE NAM HOLDS
TRUE THEN QUITE POSSIBLE TO GET DISCRETE SUPERCELLS AHEAD OF THE
DEVELOPING QLCS. HAVE NO QUESTION ABOUT OTHER SEVERE PARAMETERS AS
DEEP LAYER SHEAR AND LOW LEVEL SHEAR WILL BE OFF THE CHARTS GIVEN
STRONG LLJ AND UPPER LEVEL JET. UPPER LEVEL JET STREAK DYNAMICS
WITH RIGHT ENTRANCE REGION MOVING OVER THE AREA MAY JUST BE ENOUGH
TO ERODE THE CAP. ALL POINTS TO BASICALLY 15-21Z BEING THE FAVORED
TIME FOR SEVERE STORMS MORE LIKELY 15-18Z. OTHER LIMITING FACTOR
WILL BE INSTABILITY AS COOLING ALOFT MAY NOT BE QUITE ENOUGH TO
PUSH CAPE TO ABOVE 1500 J/KG. THINK 1000 J/KG MORE LIKELY AND THIS
STILL COULD BE ENOUGH TO SUPPORT ROBUST UPDRAFTS FOR ROTATION.
THINK SPC DAY 2 OUTLOOK IS GOOD BUT REALLY DO NOT WANT TO UNDER-
ESTIMATE THE CAP AND UPPER LEVEL DYNAMICS BEING JUST ENOUGH OUT OF
PHASE THAT A LINE OF STRONG STORMS RESULTS. STILL QUITE A BIT OF
UNCERTIANTY IN THE FORECAST BUT ENOUGH CONFIDENCE THAT THE SEVERE
POTENTIAL SHOULD BE HIGHLIGHTED.
TRUE COLD FRONT WILL PUSH THROUGH DURING THE DAY SUNDAY SO TEMPS
MAY BE A TOUCH WARMER THAN EXPECTED. HOWEVER MON/TUE AND EVEN
CHRISTMAS DAY WILL CERTAINLY FEEL LIKE WINTER AROUND SE TX.
GFS/ECMWF STILL TRYING TO SORT OUT RETURN FLOW CHRISTMAS DAY INTO
THURSDAY. WILL KEEP SOME 20 POPS DURING THAT TIME BUT REALLY DO
NOT HAVE A GOOD FEEL FOR PRECIP. LIKELY DEPENDS ON WHERE STRONGEST
ISENTROPIC LIFT SETS UP AND MODELS DIFFER BY SEVERAL HUNDERED
MILES ON WHERE THAT IS. ALSO NOTICED THAT ECMWF IS STRONGER WITH
COLD FRONT LATE NEXT THAN THE GFS WHICH HAS SEEMED TO BACK OFF.
OVERALL KEPT TREND OF ECMWF KEEPING TEMPS COLDER.
39
MARINE...
PATCHY FOG REMAINS PROBLEMATIC IN AND AROUND GALVESTON BAY WITH
VISIBILITIES FALLING TO BELOW ONE MILE AT TIMES. WITH CONDITIONS
EXPECTED TO DETERIORATE THROUGH THE EVENING HAVE ISSUED A MARINE
DENSE FOG ADVISORY FOR GALVESTON BAY AND THE ADJACENT NEARSHORE
WATERS THROUGH EARLY SATURDAY. SMALL CRAFT ADVISORY WILL REMAIN IN
PLACE FOR THE OFFSHORE WATERS THROUGH THE OVERNIGHT HOURS WITH
CAUTION FLAGS RAISED ACROSS THE NEARSHORE WATERS AND BAYS AS WINDS
INCREASE THIS EVENING.
38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 69 72 45 62 31 / 50 80 10 10 0
HOUSTON (IAH) 70 77 49 69 35 / 40 70 30 10 0
GALVESTON (GLS) 65 71 55 68 42 / 20 60 30 10 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH SATURDAY AFTERNOON
FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20
NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
DENSE FOG ADVISORY UNTIL 5 AM CST SATURDAY FOR THE FOLLOWING
ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO FREEPORT
OUT 20 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM CST SATURDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
60 NM.
&&
$$
DISCUSSION...31
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
649 PM CST FRI DEC 20 2013
.AVIATION...
IFR CONDITIONS WILL PREVAIL THROUGH AT LEAST 18Z SATURDAY WITH
SOME IMPROVEMENT TO MVFR BY MID AFTERNOON /21Z/. A COLD FRONT HAD
MOVED TO SOUTH OF A KSLR /SULPHUR SPRINGS/...KACT /WACO...KBBD
/BRADY/ LINE AS OF 00Z. THIS FRONT IS EXPECTED TO STALL SLIGHTLY
SOUTH OF THIS LOCATION LATER TONIGHT. UPPER LEVEL LOW OVER
SOUTHEASTERN ARIZONA WILL MOVE INTO FAR WEST TEXAS BY DAYBREAK
SATURDAY /12Z/ AND THEN MOVE NORTHEAST INTO NORTHWESTERN OKLAHOMA
BY SUNSET SATURDAY /00Z SUNDAY/. LIFT FROM THIS SYSTEM ALONG WITH
WARM MOIST AIR OVERRUNNING A SHALLOW COLD FRONT WILL RESULT IN
WIDESPREAD RAIN AND LOW CEILINGS THROUGH MOST OF SATURDAY
AFTERNOON. THE RAIN SHOULD COME TO AN END AND CEILINGS ARE
EXPECTED TO IMPROVE BY LATE SATURDAY AFTERNOON WITH VFR
CONDITIONS EXPECTED AFTER 00Z SUNDAY.
58
&&
.UPDATE...
WILL GO AHEAD AND ADD SOME FREEZING RAIN TO THE FAR NORTHWESTERN
PORTIONS OF NORTH TEXAS...ROUGHLY ALONG AND NORTH OF A GAINESVILLE
TO GRAHAM LINE. TEMPERATURES ARE HOVERING AT 32 TO 33 DEGREES IN
THESE LOCATIONS AND WE DO NOT EXPECT ANY ACCUMULATIONS ON THE
GROUND. SOME ELEVATED SURFACES SUCH AS CARS...TABLES...TREES
ETC. MAY SEE SOME MINOR ACCUMULATIONS. TEMPERATURES MAY ACTUALLY WARM
A DEGREE OR TWO AFTER MIDNIGHT AS PRECIPITATION INTENSITY INCREASES
AND SOME OF THE 50+ DEGREE AIR WITHIN THE WARM NOSE ALOFT MIXES
DOWN.
ELSEWHERE...WE ARE STILL EXPECTING THE HEAVIEST RAINFALL
OVERNIGHT THROUGH SATURDAY MORNING AND NO OTHER CHANGES ARE
PLANNED AT THIS TIME.
30
&&
.PREV DISCUSSION... /ISSUED 411 PM CST FRI DEC 20 2013/
21Z SUBJECTIVE SURFACE ANALYSIS SHOWED A STRONG COLD FRONT IN
PLACE ALONG A LINE FROM PARIS TO DALLAS TO HAMILTON. THE
TEMPERATURE GRADIENT ALONG THIS BOUNDARY WAS QUITE IMPRESSIVE WITH
A 70 DEGREE TEMPERATURE THAT WAS OBSERVED AT GREENVILLE...A 49
DEGREE TEMPERATURE AT MCKINNEY AND A 39 DEGREE TEMPERATURE AT
DENTON. THIS FRONT WAS STILL MOVING SOUTHEAST AT 15 MPH AT THE
TIME OF THIS DISCUSSION. A 20Z AIRPLANE SOUNDING FROM DALLAS LOVE
FIELD INDICATED THAT THE FRONT WAS SHALLOW IN NATURE...WITH THE
FRONTAL INVERSION ONLY EXTENDING UP ABOUT 1500 FEET ABOVE GROUND
LEVEL. THE FRONT IS STILL EXPECTED TO STALL OUT OVER THE FAR
SOUTHEASTERN CWA THIS EVENING...IN RESPONSE TO CYCLOGENESIS
INITIATED BY THE APPROACH OF A POWERFUL UPPER LEVEL STORM SYSTEM.
THIS UPPER LEVEL STORM SYSTEM WAS OBSERVED OVER BAJA CALIFORNIA AT
20Z BASED ON WATER VAPOR SATELLITE IMAGERY. OUT AHEAD OF THIS
UPPER LEVEL STORM SYSTEM...WATER VAPOR SATELLITE IMAGERY SHOWED A
NICE CONTINUOUS BAND OF SUB-TROPICAL PACIFIC MOISTURE STREAMING
NORTHEAST OVER NORTHERN MEXICO AND THE SOUTH PLAINS. THE HIGH
TERRAIN OF NORTHERN MEXICO WILL SCOUR OUT ALL OF THE LOW TO MID-
TROPOSPHERIC MOISTURE ASSOCIATED WITH THIS SUBTROPICAL PLUME...BUT
THE MID TO UPPER LEVEL MOISTURE WILL CONTRIBUTE TO MOISTURE DEPTH
OVER THE REGION AS THE UPPER LEVEL STORM SYSTEM MOVES ACROSS THE
AREA TONIGHT INTO TOMORROW MORNING.
THROUGH TONIGHT...THE MOST TROUBLESOME FORECAST PROBLEM IN THE
SHORT TERM FORECAST IS THAT ALL FORECAST GUIDANCE IS DOING A
REMARKABLY POOR JOB RESOLVING THE STRENGTH OF THE SHALLOW COLD AIR
ASSOCIATED WITH/BEHIND THE COLD FRONT. WHILE ALL GUIDANCE IS DOING
A POOR JOB RESOLVING SURFACE TEMPERATURES NORTH OF THE COLD
FRONT...THE RAP IN PARTICULAR IS DIFFICULT TO PROCESS BECAUSE IT
CONTINUES TO INITIALIZE THE COLD AIR...BUT PERSISTENTLY BRINGS
SURFACE TEMPERATURES UP 5-7 DEGREES AT FORECAST HOUR 1 DESPITE
PERSISTENT COLD AIR ADVECTION AND CLOUD COVER. THIS WOULD BE MORE
OR LESS A NUISANCE IF THE TEMPERATURES HAD NO POTENTIAL TO HAVE AN
IMPACT ON PRECIPITATION TYPE IN THIS FORECAST. FOR INSTANCE...AT
BOWIE...THE 21Z OBSERVATION HAD A TEMPERATURE OF 32 DEG F. THE RAP
INITIALIZES THIS AT 34 DEGREES...WHICH IS NOT TOO FAR OFF...BUT
THEN GOES AHEAD TO FORECAST A TEMPERATURE OF 40 DEGREES BY 22Z.
WITH WIDESPREAD RAINFALL DEVELOPING OVER THE REGION RIGHT
NOW...AND EXPECTED TO PERSIST THIS EVENING INTO THE OVERNIGHT
HOURS...THIS ERROR IN RESOLVING NEAR SURFACE TEMPERATURES IS QUITE
PROBLEMATIC. THEREFORE...AT THIS TIME...WITH NO GUIDANCE AVAILABLE
ACTUALLY RESOLVING THE STRENGTH OF THIS COLD AIR...THE
PRECIPITATION TYPE FORECAST FOR TONIGHT WAS COMPLETED USING
OBSERVATIONAL TRENDS...RECENT FORECAST EVENTS AND INTUITION.
AT THIS TIME EXPECT THAT TEMPERATURES ALONG AND NORTHWEST OF A
GAINESVILLE TO GRAHAM LINE ARE MOST LIKELY TO FALL TO 32 DEGREES
THIS EVENING...LIKELY HOLDING STEADY THROUGH MUCH OF THE OVERNIGHT
HOURS. AS A RESULT...EVEN IF WE SEE RAIN AT 31 TO 32 DEGREES FOR
SEVERAL HOURS...THE CURRENT THINKING IS THAT WE WILL NOT SEE ANY
ICE ACCUMULATION...EXCEPT PERHAPS ON TREE TOPS OR THE TOPS OF
EXPOSED METAL SURFACES. THE REASONS FOR THIS ARE AS FOLLOWS:
1. BEFORE THE FRONT...WE HAVE EXPERIENCED A FEW DAYS OF ABOVE
NORMAL TEMPERATURES. GROUND/ROAD TEMPERATURES ARE WELL ABOVE
FREEZING WHICH WILL NOT ALLOW FOR ICE ACCUMULATION.
2. THE DEPTH OF THE ELEVATED WARM LAYER IS ALMOST 8 TIMES AS DEEP
AS THE DEPTH OF THE COLD/SUB-FREEZING LAYER. RAIN FALLING IN THIS
ENVIRONMENT WILL LIKELY HAVE A TEMPERATURE ABOVE FREEZING WHEN IT
REACHES THE SURFACE. THAT IS THE TEMPERATURE OF THE FALLING RAIN
DROPS ARE LIKELY TO BE ABOVE FREEZING...THIS IS ALSO NOT CONDUCIVE
TO ICE ACCUMULATION.
3. ALL GUIDANCE INDICATES PERSISTENT WARM AIR ADVECTION THROUGH
12Z SATURDAY ABOVE THE COLD FRONTAL INVERSION. THE WARM LAYER IS
VERY LIKELY TO MAINTAIN ITS DEPTH AND STRENGTH...WHILE RELATIVELY
WARM RAIN DROPS MAY ACTUALLY SHRINK THE DEPTH OF THE SHALLOW COLD
AIR OVERNIGHT.
AS A RESULT...WILL NOT BE HIGHLIGHTING FREEZING RAIN IN THE
FORECAST AT THIS TIME...DESPITE THE SURFACE OBSERVATION AT BOWIE
AT 32 DEGREES SEEMINGLY SHOWING AN ICE STORM ON OUR DOORSTEP. IT
LOOKS LIKE THE DEPTH OF THE COLD AIR WILL ONLY SUPPORT ICE
ACCUMULATION FARTHER NORTH...WELL INTO OKLAHOMA BASED ON
OBSERVATIONAL ANALYSIS AND DFW AREA AIRCRAFT SOUNDINGS.
DESPITE ALL THAT HAS BEEN DISCUSSED ABOUT THE SHALLOW COLD AIR
PROBLEM...THERE WERE ACTUALLY NO SIGNIFICANT CHANGES MADE TO THE
PREVIOUS FORECAST WHICH REMAINS LARGELY ON TRACK. THE BAJA UPPER
LEVEL LOW IS STILL EXPECTED TO MOVE OVER THE SOUTH PLAINS TOMORROW
MORNING...SPREADING STRONG LARGE SCALE FORCING FOR ASCENT OVER THE
REGION TONIGHT THROUGH TOMORROW MORNING. NEARLY ALL GUIDANCE
INDICATES THAT THE UPPER LOW WILL BECOME INCREASINGLY NEGATIVELY
TILTED AS IT MOVES OUT OVER TEXAS...DEEPENING AS IT MOVES OVER THE
CWA. THE STRONGEST FORCING FOR ASCENT LOOKS TO MOVE OVER THE CWA
IN THE 09 TO 15Z TIME FRAME...WHICH SHOULD ALSO REPRESENT OUR
WINDOW FOR THE BEST COVERAGE AND HEAVIEST PRECIPITATION RATES
DURING THIS EVENT.
FOR THIS EVENING...THE COLD FRONT PUSHING SOUTH THROUGH MOST OF
THE CWA WILL SIMPLY HELP TO STEEPEN LOW-LEVEL ISENTROPIC SURFACES
AS CYCLOGENESIS RAMPS UP NEAR DEL RIO RESULTING IN AN INCREASE OF
THE STRENGTH OF THE LOW TO MID-LEVEL WIND FIELD. THIS SHOULD
RESULT IN A SPREAD OF THE COVERAGE OF ONGOING RAIN SHOWER
ACTIVITY FROM WEST TO EAST ACROSS THE CWA. AS THE UPPER LEVEL LOW
APPROACHES...ASSUMING IT BECOMES MORE NEGATIVELY TILTED AS
ADVERTISED...WE SHOULD SEE AN ENHANCEMENT OF MID-LEVEL LAPSE RATES
WITH SOME UPPER-LEVEL COLD AIR ADVECTION OVER THE PERSISTENT LOW-
LEVEL WARM AIR ADVECTION REGIME. THIS WILL RESULT IN AN INCREASED
CHANCE OF ISOLATED THUNDERSTORMS EMBEDDED IN THE RAIN SHOWER
ACTIVITY FROM SUNSET TO MIDNIGHT. ALL OF THIS ACTIVITY SHOULD
REMAIN ELEVATED IN NATURE...AND POSES VERY LITTLE SEVERE WEATHER
THREAT AS A RESULT. RAINFALL RATES WILL BE ENHANCED...AND
THEREFORE SOME LOCALIZED HEAVY RAINFALL IS POSSIBLE.
AFTER MIDNIGHT...AS MENTIONED ABOVE...THE BEST LARGE SCALE FORCING
FOR ASCENT IS EXPECTED TO BUILD ACROSS THE CWA FROM WEST TO EAST
DURING THIS TIME RESULTING IN THE STRONGEST AND MOST WIDESPREAD
CONVECTION AND PRECIPITATION FOR THE REGION. BASED ON THE POSITION
OF THE COLD FRONT AT THAT TIME...WE DO HAVE A WINDOW FOR SURFACE
BASED SEVERE STORMS BASED ON CONVECTIVE PARAMETERS ADVERTISED IN
THE MAJORITY OF GUIDANCE. LOCATIONS ALONG AND SOUTHEAST OF
WHEREVER THE COLD FRONT STALLS OUT WOULD BE THE ONLY LOCATIONS
WHERE SURFACE BASED SEVERE STORMS WOULD BE POSSIBLE. FORECAST
CONVECTIVE PARAMETERS INDICATED SURFACE BASED CAPE VALUES OF
AROUND 1000 J/KG WITH 0-3 KM CAPE VALUES OF AROUND 100 J/KG AND
DEEP LAYER SHEAR VALUES IN EXCESS OF 50 KTS.
THESE VALUES ARE SUPPORTIVE OF A LOW-TOPPED SUPER CELLULAR STORM
MODE...WHICH COULD RESULT IN LARGE HAIL...DAMAGING WIND OR
ISOLATED TORNADOES. THIS THREAT IS MODERATED BY STRONG FORCING
WHICH MAY MAKE AN ISOLATED STORM MODE DIFFICULT TO REALIZE...AND
STRONG CLOUD LEVEL WINDS THAT WILL LIKELY TAKE STORMS THAT DEVELOP
ALONG THE FRONT...OVER/NORTH OF THE FRONT SHORTLY AFTER
INITIATION. REGARDLESS...WILL BE WATCHING FOR WHERE THE FRONT
STALLS OUT TONIGHT AS LOCATIONS NEAR AND TO THE SOUTHEAST OF THE
BOUNDARY ARE THE MOST LIKELY TO SEE SEVERE WEATHER. FURTHER
NORTHWEST...STRONG STORMS REMAIN POSSIBLE...HOWEVER EVEN ELEVATED
SUPERCELLS ARE ONLY GOING TO PROVIDE A THREAT FOR MARGINALLY
SEVERE HAIL...SO THE OVERALL SEVERE WEATHER THREAT NORTHWEST OF
THE FRONT DIMINISHES GREATLY.
FOR ANYWHERE ACROSS NORTH TEXAS...LOCALLY HEAVY RAINFALL IS
POSSIBLE WHICH MAY RESULT IN SOME LOCALIZED FLASH FLOODING ISSUES
OVER THE NEXT 24 HRS. WITH THE SUB-TROPICAL PACIFIC MOISTURE FEED
IN PLACE...AND LOW-LEVEL WARM MOIST ADVECTION EXPECTED TO RAMP UP
IN INTENSITY OVER THE SHALLOW COLD FRONT...NEARLY ALL GUIDANCE
INDICATES THAT PWAT VALUES WILL BE UP AROUND 1.5 INCHES ACROSS
NORTH AND CENTRAL TEXAS AS THE UPPER LOW SPREADS STRONG FORCING
OVER THE REGION. 1.5 INCH PRECIPITABLE WATER VALUES RANK AS PLUS 3
STANDARD DEVIATION FOR NORTH TEXAS AT THIS TIME OF YEAR. THIS
EXCEPTIONALLY DEEP MOISTURE COMBINED WITH FAVORABLE DYNAMICS FOR
WIDESPREAD PRECIPITATION SUPPORT A LOCALIZED HEAVY RAINFALL THREAT
WITH AN ATTENDANT LOCALIZED FLOODING THREAT TONIGHT INTO TOMORROW
MORNING. DID NOT ISSUE A FLASH FLOOD WATCH AT THIS TIME BECAUSE
OUR PRIMARY WINDOW FOR HEAVY RAINFALL IS ONLY EXPECTED TO BE ON
THE ORDER OF 6 HOURS OR SO. IF STRONG FORCING WAS EXPECTED TO BE
IN PLACE FOR A LONGER PERIOD OF TIME...THE THREAT OF WIDESPREAD
FLOODING WOULD BE MUCH GREATER AND A WATCH WOULD HAVE BEEN ISSUED.
AT THIS TIME THE THREAT OF FLOODING IS EXPECTED TO REMAIN
LOCALIZED AND MAINLY CONFINED TO LOW LYING/COMMONLY FLOODED AREAS.
HEAVY PRECIPITATION IS EXPECTED TO COME TO AN END FROM SOUTHWEST
TO NORTHEAST SATURDAY AFTERNOON AS A STRONG MID-LEVEL DRY SLOT
PUNCHES OVER THE REGION. LIGHT RAIN MAY PERSIST ACROSS THE AREA
SATURDAY AFTERNOON...BUT EVEN THIS WILL BE SCOURED OUT BY SUNSET.
REMAINDER OF THE FORECAST...NO SIGNIFICANT CHANGES WERE MADE TO
THE PREVIOUS FORECAST AS MOST OF THE ACTIVITY IN THE FORECAST IS
IN THE FIRST 24 HOURS. HIGHLIGHTS OF THE REMAINDER OF THE FORECAST
INCLUDE:
1. ADDED A MENTION OF SPRINKLES/LIGHT RAIN TO THE FORECAST ALONG
THE COLD FRONT THAT IS EXPECTED TO PUSH SOUTH THROUGH THE CWA ON
SUNDAY MORNING. WILL HAVE TO WATCH TEMPERATURES CLOSELY SUNDAY
MORNING AS THIS FRONT ROLLS THROUGH...HOWEVER ALL GUIDANCE
INDICATES TEMPERATURES JUST ABOVE FREEZING WITH THIS VERY LIGHT
PRECIPITATION.
2. WE SHOULD BE DRY EARLY NEXT WEEK...LEADING UP TO CHRISTMAS DAY.
TEMPERATURES WILL SLOWLY WARM THROUGH CHRISTMAS...ALTHOUGH HIGHS
ARE EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEK AHEAD.
3. AN UPPER LEVEL STORM SYSTEM MAY RESULT IN SCATTERED RAIN
SHOWERS ACROSS THE REGION ON CHRISTMAS DAY. AT THIS TIME
TEMPERATURES ARE EXPECTED TO BE WELL ABOVE FREEZING...SO NO
SIGNIFICANT IMPACTS ARE EXPECTED AT THIS TIME.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 37 47 36 48 29 / 100 100 10 10 5
WACO, TX 42 62 37 50 30 / 80 100 10 10 5
PARIS, TX 41 45 36 47 26 / 100 100 10 10 10
DENTON, TX 36 44 34 47 26 / 100 100 10 10 5
MCKINNEY, TX 38 44 35 46 25 / 100 100 10 10 5
DALLAS, TX 38 46 38 48 30 / 100 100 10 10 5
TERRELL, TX 41 47 37 47 28 / 100 100 10 10 5
CORSICANA, TX 46 54 39 48 30 / 80 100 10 10 5
TEMPLE, TX 46 63 39 52 31 / 80 100 10 10 5
MINERAL WELLS, TX 36 49 34 48 24 / 100 90 10 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
618 PM CST FRI DEC 20 2013
.UPDATE...
WILL GO AHEAD AND ADD SOME FREEZING RAIN TO THE FAR NORTHWESTERN
PORTIONS OF NORTH TEXAS...ROUGHLY ALONG AND NORTH OF A GAINESVILLE
TO GRAHAM LINE. TEMPERATURES ARE HOVERING AT 32 TO 33 DEGREES IN
THESE LOCATIONS AND WE DO NOT EXPECT ANY ACCUMULATIONS ON THE
GROUND. SOME ELEVATED SURFACES SUCH AS CARS...TABLES...TREES
ETC. MAY SEE SOME MINOR ACCUMULATIONS. TEMPERATURES MAY ACTUALLY WARM
A DEGREE OR TWO AFTER MIDNIGHT AS PRECIPITATION INTENSITY INCREASES
AND SOME OF THE 50+ DEGREE AIR WITHIN THE WARM NOSE ALOFT MIXES
DOWN.
ELSEWHERE...WE ARE STILL EXPECTING THE HEAVIEST RAINFALL
OVERNIGHT THROUGH SATURDAY MORNING AND NO OTHER CHANGES ARE
PLANNED AT THIS TIME.
30
&&
.PREV DISCUSSION... /ISSUED 411 PM CST FRI DEC 20 2013/
21Z SUBJECTIVE SURFACE ANALYSIS SHOWED A STRONG COLD FRONT IN
PLACE ALONG A LINE FROM PARIS TO DALLAS TO HAMILTON. THE
TEMPERATURE GRADIENT ALONG THIS BOUNDARY WAS QUITE IMPRESSIVE WITH
A 70 DEGREE TEMPERATURE THAT WAS OBSERVED AT GREENVILLE...A 49
DEGREE TEMPERATURE AT MCKINNEY AND A 39 DEGREE TEMPERATURE AT
DENTON. THIS FRONT WAS STILL MOVING SOUTHEAST AT 15 MPH AT THE
TIME OF THIS DISCUSSION. A 20Z AIRPLANE SOUNDING FROM DALLAS LOVE
FIELD INDICATED THAT THE FRONT WAS SHALLOW IN NATURE...WITH THE
FRONTAL INVERSION ONLY EXTENDING UP ABOUT 1500 FEET ABOVE GROUND
LEVEL. THE FRONT IS STILL EXPECTED TO STALL OUT OVER THE FAR
SOUTHEASTERN CWA THIS EVENING...IN RESPONSE TO CYCLOGENESIS
INITIATED BY THE APPROACH OF A POWERFUL UPPER LEVEL STORM SYSTEM.
THIS UPPER LEVEL STORM SYSTEM WAS OBSERVED OVER BAJA CALIFORNIA AT
20Z BASED ON WATER VAPOR SATELLITE IMAGERY. OUT AHEAD OF THIS
UPPER LEVEL STORM SYSTEM...WATER VAPOR SATELLITE IMAGERY SHOWED A
NICE CONTINUOUS BAND OF SUB-TROPICAL PACIFIC MOISTURE STREAMING
NORTHEAST OVER NORTHERN MEXICO AND THE SOUTH PLAINS. THE HIGH
TERRAIN OF NORTHERN MEXICO WILL SCOUR OUT ALL OF THE LOW TO MID-
TROPOSPHERIC MOISTURE ASSOCIATED WITH THIS SUBTROPICAL PLUME...BUT
THE MID TO UPPER LEVEL MOISTURE WILL CONTRIBUTE TO MOISTURE DEPTH
OVER THE REGION AS THE UPPER LEVEL STORM SYSTEM MOVES ACROSS THE
AREA TONIGHT INTO TOMORROW MORNING.
THROUGH TONIGHT...THE MOST TROUBLESOME FORECAST PROBLEM IN THE
SHORT TERM FORECAST IS THAT ALL FORECAST GUIDANCE IS DOING A
REMARKABLY POOR JOB RESOLVING THE STRENGTH OF THE SHALLOW COLD AIR
ASSOCIATED WITH/BEHIND THE COLD FRONT. WHILE ALL GUIDANCE IS DOING
A POOR JOB RESOLVING SURFACE TEMPERATURES NORTH OF THE COLD
FRONT...THE RAP IN PARTICULAR IS DIFFICULT TO PROCESS BECAUSE IT
CONTINUES TO INITIALIZE THE COLD AIR...BUT PERSISTENTLY BRINGS
SURFACE TEMPERATURES UP 5-7 DEGREES AT FORECAST HOUR 1 DESPITE
PERSISTENT COLD AIR ADVECTION AND CLOUD COVER. THIS WOULD BE MORE
OR LESS A NUISANCE IF THE TEMPERATURES HAD NO POTENTIAL TO HAVE AN
IMPACT ON PRECIPITATION TYPE IN THIS FORECAST. FOR INSTANCE...AT
BOWIE...THE 21Z OBSERVATION HAD A TEMPERATURE OF 32 DEG F. THE RAP
INITIALIZES THIS AT 34 DEGREES...WHICH IS NOT TOO FAR OFF...BUT
THEN GOES AHEAD TO FORECAST A TEMPERATURE OF 40 DEGREES BY 22Z.
WITH WIDESPREAD RAINFALL DEVELOPING OVER THE REGION RIGHT
NOW...AND EXPECTED TO PERSIST THIS EVENING INTO THE OVERNIGHT
HOURS...THIS ERROR IN RESOLVING NEAR SURFACE TEMPERATURES IS QUITE
PROBLEMATIC. THEREFORE...AT THIS TIME...WITH NO GUIDANCE AVAILABLE
ACTUALLY RESOLVING THE STRENGTH OF THIS COLD AIR...THE
PRECIPITATION TYPE FORECAST FOR TONIGHT WAS COMPLETED USING
OBSERVATIONAL TRENDS...RECENT FORECAST EVENTS AND INTUITION.
AT THIS TIME EXPECT THAT TEMPERATURES ALONG AND NORTHWEST OF A
GAINESVILLE TO GRAHAM LINE ARE MOST LIKELY TO FALL TO 32 DEGREES
THIS EVENING...LIKELY HOLDING STEADY THROUGH MUCH OF THE OVERNIGHT
HOURS. AS A RESULT...EVEN IF WE SEE RAIN AT 31 TO 32 DEGREES FOR
SEVERAL HOURS...THE CURRENT THINKING IS THAT WE WILL NOT SEE ANY
ICE ACCUMULATION...EXCEPT PERHAPS ON TREE TOPS OR THE TOPS OF
EXPOSED METAL SURFACES. THE REASONS FOR THIS ARE AS FOLLOWS:
1. BEFORE THE FRONT...WE HAVE EXPERIENCED A FEW DAYS OF ABOVE
NORMAL TEMPERATURES. GROUND/ROAD TEMPERATURES ARE WELL ABOVE
FREEZING WHICH WILL NOT ALLOW FOR ICE ACCUMULATION.
2. THE DEPTH OF THE ELEVATED WARM LAYER IS ALMOST 8 TIMES AS DEEP
AS THE DEPTH OF THE COLD/SUB-FREEZING LAYER. RAIN FALLING IN THIS
ENVIRONMENT WILL LIKELY HAVE A TEMPERATURE ABOVE FREEZING WHEN IT
REACHES THE SURFACE. THAT IS THE TEMPERATURE OF THE FALLING RAIN
DROPS ARE LIKELY TO BE ABOVE FREEZING...THIS IS ALSO NOT CONDUCIVE
TO ICE ACCUMULATION.
3. ALL GUIDANCE INDICATES PERSISTENT WARM AIR ADVECTION THROUGH
12Z SATURDAY ABOVE THE COLD FRONTAL INVERSION. THE WARM LAYER IS
VERY LIKELY TO MAINTAIN ITS DEPTH AND STRENGTH...WHILE RELATIVELY
WARM RAIN DROPS MAY ACTUALLY SHRINK THE DEPTH OF THE SHALLOW COLD
AIR OVERNIGHT.
AS A RESULT...WILL NOT BE HIGHLIGHTING FREEZING RAIN IN THE
FORECAST AT THIS TIME...DESPITE THE SURFACE OBSERVATION AT BOWIE
AT 32 DEGREES SEEMINGLY SHOWING AN ICE STORM ON OUR DOORSTEP. IT
LOOKS LIKE THE DEPTH OF THE COLD AIR WILL ONLY SUPPORT ICE
ACCUMULATION FARTHER NORTH...WELL INTO OKLAHOMA BASED ON
OBSERVATIONAL ANALYSIS AND DFW AREA AIRCRAFT SOUNDINGS.
DESPITE ALL THAT HAS BEEN DISCUSSED ABOUT THE SHALLOW COLD AIR
PROBLEM...THERE WERE ACTUALLY NO SIGNIFICANT CHANGES MADE TO THE
PREVIOUS FORECAST WHICH REMAINS LARGELY ON TRACK. THE BAJA UPPER
LEVEL LOW IS STILL EXPECTED TO MOVE OVER THE SOUTH PLAINS TOMORROW
MORNING...SPREADING STRONG LARGE SCALE FORCING FOR ASCENT OVER THE
REGION TONIGHT THROUGH TOMORROW MORNING. NEARLY ALL GUIDANCE
INDICATES THAT THE UPPER LOW WILL BECOME INCREASINGLY NEGATIVELY
TILTED AS IT MOVES OUT OVER TEXAS...DEEPENING AS IT MOVES OVER THE
CWA. THE STRONGEST FORCING FOR ASCENT LOOKS TO MOVE OVER THE CWA
IN THE 09 TO 15Z TIME FRAME...WHICH SHOULD ALSO REPRESENT OUR
WINDOW FOR THE BEST COVERAGE AND HEAVIEST PRECIPITATION RATES
DURING THIS EVENT.
FOR THIS EVENING...THE COLD FRONT PUSHING SOUTH THROUGH MOST OF
THE CWA WILL SIMPLY HELP TO STEEPEN LOW-LEVEL ISENTROPIC SURFACES
AS CYCLOGENESIS RAMPS UP NEAR DEL RIO RESULTING IN AN INCREASE OF
THE STRENGTH OF THE LOW TO MID-LEVEL WIND FIELD. THIS SHOULD
RESULT IN A SPREAD OF THE COVERAGE OF ONGOING RAIN SHOWER
ACTIVITY FROM WEST TO EAST ACROSS THE CWA. AS THE UPPER LEVEL LOW
APPROACHES...ASSUMING IT BECOMES MORE NEGATIVELY TILTED AS
ADVERTISED...WE SHOULD SEE AN ENHANCEMENT OF MID-LEVEL LAPSE RATES
WITH SOME UPPER-LEVEL COLD AIR ADVECTION OVER THE PERSISTENT LOW-
LEVEL WARM AIR ADVECTION REGIME. THIS WILL RESULT IN AN INCREASED
CHANCE OF ISOLATED THUNDERSTORMS EMBEDDED IN THE RAIN SHOWER
ACTIVITY FROM SUNSET TO MIDNIGHT. ALL OF THIS ACTIVITY SHOULD
REMAIN ELEVATED IN NATURE...AND POSES VERY LITTLE SEVERE WEATHER
THREAT AS A RESULT. RAINFALL RATES WILL BE ENHANCED...AND
THEREFORE SOME LOCALIZED HEAVY RAINFALL IS POSSIBLE.
AFTER MIDNIGHT...AS MENTIONED ABOVE...THE BEST LARGE SCALE FORCING
FOR ASCENT IS EXPECTED TO BUILD ACROSS THE CWA FROM WEST TO EAST
DURING THIS TIME RESULTING IN THE STRONGEST AND MOST WIDESPREAD
CONVECTION AND PRECIPITATION FOR THE REGION. BASED ON THE POSITION
OF THE COLD FRONT AT THAT TIME...WE DO HAVE A WINDOW FOR SURFACE
BASED SEVERE STORMS BASED ON CONVECTIVE PARAMETERS ADVERTISED IN
THE MAJORITY OF GUIDANCE. LOCATIONS ALONG AND SOUTHEAST OF
WHEREVER THE COLD FRONT STALLS OUT WOULD BE THE ONLY LOCATIONS
WHERE SURFACE BASED SEVERE STORMS WOULD BE POSSIBLE. FORECAST
CONVECTIVE PARAMETERS INDICATED SURFACE BASED CAPE VALUES OF
AROUND 1000 J/KG WITH 0-3 KM CAPE VALUES OF AROUND 100 J/KG AND
DEEP LAYER SHEAR VALUES IN EXCESS OF 50 KTS.
THESE VALUES ARE SUPPORTIVE OF A LOW-TOPPED SUPER CELLULAR STORM
MODE...WHICH COULD RESULT IN LARGE HAIL...DAMAGING WIND OR
ISOLATED TORNADOES. THIS THREAT IS MODERATED BY STRONG FORCING
WHICH MAY MAKE AN ISOLATED STORM MODE DIFFICULT TO REALIZE...AND
STRONG CLOUD LEVEL WINDS THAT WILL LIKELY TAKE STORMS THAT DEVELOP
ALONG THE FRONT...OVER/NORTH OF THE FRONT SHORTLY AFTER
INITIATION. REGARDLESS...WILL BE WATCHING FOR WHERE THE FRONT
STALLS OUT TONIGHT AS LOCATIONS NEAR AND TO THE SOUTHEAST OF THE
BOUNDARY ARE THE MOST LIKELY TO SEE SEVERE WEATHER. FURTHER
NORTHWEST...STRONG STORMS REMAIN POSSIBLE...HOWEVER EVEN ELEVATED
SUPERCELLS ARE ONLY GOING TO PROVIDE A THREAT FOR MARGINALLY
SEVERE HAIL...SO THE OVERALL SEVERE WEATHER THREAT NORTHWEST OF
THE FRONT DIMINISHES GREATLY.
FOR ANYWHERE ACROSS NORTH TEXAS...LOCALLY HEAVY RAINFALL IS
POSSIBLE WHICH MAY RESULT IN SOME LOCALIZED FLASH FLOODING ISSUES
OVER THE NEXT 24 HRS. WITH THE SUB-TROPICAL PACIFIC MOISTURE FEED
IN PLACE...AND LOW-LEVEL WARM MOIST ADVECTION EXPECTED TO RAMP UP
IN INTENSITY OVER THE SHALLOW COLD FRONT...NEARLY ALL GUIDANCE
INDICATES THAT PWAT VALUES WILL BE UP AROUND 1.5 INCHES ACROSS
NORTH AND CENTRAL TEXAS AS THE UPPER LOW SPREADS STRONG FORCING
OVER THE REGION. 1.5 INCH PRECIPITABLE WATER VALUES RANK AS PLUS 3
STANDARD DEVIATION FOR NORTH TEXAS AT THIS TIME OF YEAR. THIS
EXCEPTIONALLY DEEP MOISTURE COMBINED WITH FAVORABLE DYNAMICS FOR
WIDESPREAD PRECIPITATION SUPPORT A LOCALIZED HEAVY RAINFALL THREAT
WITH AN ATTENDANT LOCALIZED FLOODING THREAT TONIGHT INTO TOMORROW
MORNING. DID NOT ISSUE A FLASH FLOOD WATCH AT THIS TIME BECAUSE
OUR PRIMARY WINDOW FOR HEAVY RAINFALL IS ONLY EXPECTED TO BE ON
THE ORDER OF 6 HOURS OR SO. IF STRONG FORCING WAS EXPECTED TO BE
IN PLACE FOR A LONGER PERIOD OF TIME...THE THREAT OF WIDESPREAD
FLOODING WOULD BE MUCH GREATER AND A WATCH WOULD HAVE BEEN ISSUED.
AT THIS TIME THE THREAT OF FLOODING IS EXPECTED TO REMAIN
LOCALIZED AND MAINLY CONFINED TO LOW LYING/COMMONLY FLOODED AREAS.
HEAVY PRECIPITATION IS EXPECTED TO COME TO AN END FROM SOUTHWEST
TO NORTHEAST SATURDAY AFTERNOON AS A STRONG MID-LEVEL DRY SLOT
PUNCHES OVER THE REGION. LIGHT RAIN MAY PERSIST ACROSS THE AREA
SATURDAY AFTERNOON...BUT EVEN THIS WILL BE SCOURED OUT BY SUNSET.
REMAINDER OF THE FORECAST...NO SIGNIFICANT CHANGES WERE MADE TO
THE PREVIOUS FORECAST AS MOST OF THE ACTIVITY IN THE FORECAST IS
IN THE FIRST 24 HOURS. HIGHLIGHTS OF THE REMAINDER OF THE FORECAST
INCLUDE:
1. ADDED A MENTION OF SPRINKLES/LIGHT RAIN TO THE FORECAST ALONG
THE COLD FRONT THAT IS EXPECTED TO PUSH SOUTH THROUGH THE CWA ON
SUNDAY MORNING. WILL HAVE TO WATCH TEMPERATURES CLOSELY SUNDAY
MORNING AS THIS FRONT ROLLS THROUGH...HOWEVER ALL GUIDANCE
INDICATES TEMPERATURES JUST ABOVE FREEZING WITH THIS VERY LIGHT
PRECIPITATION.
2. WE SHOULD BE DRY EARLY NEXT WEEK...LEADING UP TO CHRISTMAS DAY.
TEMPERATURES WILL SLOWLY WARM THROUGH CHRISTMAS...ALTHOUGH HIGHS
ARE EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEK AHEAD.
3. AN UPPER LEVEL STORM SYSTEM MAY RESULT IN SCATTERED RAIN
SHOWERS ACROSS THE REGION ON CHRISTMAS DAY. AT THIS TIME
TEMPERATURES ARE EXPECTED TO BE WELL ABOVE FREEZING...SO NO
SIGNIFICANT IMPACTS ARE EXPECTED AT THIS TIME.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 37 47 36 48 29 / 100 100 10 10 5
WACO, TX 42 62 37 50 30 / 80 100 10 10 5
PARIS, TX 41 45 36 47 26 / 100 100 10 10 10
DENTON, TX 37 44 34 47 26 / 100 100 10 10 5
MCKINNEY, TX 38 44 35 46 25 / 100 100 10 10 5
DALLAS, TX 38 46 38 48 30 / 100 100 10 10 5
TERRELL, TX 41 47 37 47 28 / 100 100 10 10 5
CORSICANA, TX 46 54 39 48 30 / 80 100 10 10 5
TEMPLE, TX 46 63 39 52 31 / 80 100 10 10 5
MINERAL WELLS, TX 36 49 34 48 24 / 100 90 10 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1003 AM CST THU DEC 19 2013
.UPDATE...
MORNING FORECAST UPDATE.
&&
.DISCUSSION...
GULF MOISTURE CONTINUES TO DEEPEN OVER THE AREA WITH SFC DEWPOINT
TEMPS IN THE 60S PUSH INTO THE COAST AND HOUSTON AREA. REGIONAL
RADAR SHOW ISO SHOWERS ACROSS THE AREA AND EXPECT THIS TREND TO
CONTINUE INTO THE AFTERNOON. WATER VAPOR IMAGERY SHOWS A WEAK
SHORTWAVE TROUGH MOVING ACROSS THE AREA WHICH MAY BE ENHANCING
SOME OF THE ACTIVITY. WAVE IS MOVING OUT OF THE AREA SO MAY SEE
SHOWER ACTIVITY TAPER OFF THIS AFTERNOON. MAIN CHANGE IN FORECAST
FOR TODAY WAS TO GO WITH 20 POPS AND ISO SHRA FOR WX GRIDS.
WILL CONTINUE TO EVALUATE SEVERE WEATHER POTENTIAL FOR SATURDAY.
LOOKS LIKE EARLY 12Z MODEL TRENDS ARE FOR AN EARLIER SCENARIO BY
3-6 HRS. DETAILS OF THE EVENT MAY BE COMING TOGETHER BUT STILL
THINK EVENT WILL HINGE ON THE CAP BREAKING AND AVAILABLE
INSTABILITY.
39
&&
.PREV DISCUSSION... /ISSUED 542 AM CST THU DEC 19 2013/
DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
AVIATION...
MADE A FEW CHANGES TO THE TAFS AS MOISTURE RETURN IS A BIT MORE
AGGRESSIVE. RADAR IS ALREADY SHOWING LIGHT RAIN ALONG THE COAST.
FCST SOUNDINGS SHOW CIGS GRADUALLY LOWERING THROUGH THE DAY AND
THE SOUNDINGS BECOME SATURATED BETWEEN 900 AND 800 MB. SOUNDINGS
ARE STRONGLY CAPPED BUT FEEL STREAMER SHOWERS WILL PERSIST THROUGH
THE AFTN. CIGS SHOULD LOWER FURTHER OVERNIGHT AND LIFR CONDS
POSSIBLE BY FRI MORNING. VERY STRONG WINDS OFF THE SURFACE SHOULD
MIX DOWNWARD TODAY SO WILL MAINTAIN GUSTS THIS AFTN. NAM12 SHOWS
45 KNOTS AT 850 MB THIS AFTN SO MAYBE WINDS NEED TO BE NUDGED
UPWARD. 43
PREV DISCUSSION... /ISSUED 440 AM CST THU DEC 19 2013/
DISCUSSION...
LOW LIGHT SATELLITE SHOWING MOSTLY CLOUDY SKIES ACROSS SOUTHEAST
TEXAS THIS MORNING. RADAR IS ALSO STARTING TO PICK UP VERY LIGHT
RETURNS OVER THE COASTAL WATERS TO THE SOUTHWEST. NAM 12 SHOWING
SOME LIGHT PVA CURRENTLY MOVING OVER THE SOUTHWESTERN AREAS. KCRP
SOUNDING ALSO SHOWS A PRETTY THICK SATURATED LAYER. THE PVA WEDGE
WILL CONTINUE TO PUSH TOWARDS THE NORTHEAST DURING THE DAY TODAY
AND IN COMBINATION WITH THE WAA THINK LIGHT STREAMER SHOWERS AND
DRIZZLE WILL BE POSSIBLE. HIGH RES HRRR AND TEXAS TECH WRF ALSO
SUPPORT THIS. THIS TREND OF LIGHT SHOWERS UNDERNEATH THE CAP WILL
PERSIST TODAY AND FRIDAY AHEAD OF THE NEXT UPPER LEVEL SYSTEM.
AS HAS BEEN ADVERTISED THE LAST COUPLE OF DAYS A SHORTWAVE IS
CURRENTLY DIVING SOUTHWARDS FROM THE PACIFIC NORTHWEST. THIS
ENERGY WILL EVENTUALLY WRAP UP INTO AN UPPER LEVEL LOW OVER THE
BAJA OF CALIFORNIA. THE UPPER LEVEL LOW WILL THEN TRACK EASTWARDS
AND EJECT OFF TOWARDS THE NORTHEAST OVER THE TEXAS PANHANDLE.
MODELS ARE STILL SHOWING THE LOW TO GAIN A NEGATIVE TILT TO IT.
UPPER LEVEL DYNAMICS APPEAR TO BE MORE FAVORABLE AGAIN FOR
SATURDAY AS THE ECMWF... GFS... CANADIAN... AND NAM 12 ALL PUT
SOUTHEAST TEXAS IN THE RRQ. SHEAR VALUES REMAIN IMPRESSIVE. 30 KTS
OR GREATER OF SFC TO 1KM SHEAR (SRH ~220 M2/S2) CAN BE FOUND IN
MOST FORECAST SOUNDINGS WITH MODEST CAPE VALUES. WHAT REMAINS TO
BE IN QUESTION IS HOW MUCH DRY AIR AND CAPPING SOUTHEAST TEXAS
WILL HAVE. ECMWF FORECAST SOUNDINGS ARE BY FAR THE MOST MOIST WITH
PWATS APPROACHING 2.00" IN THE IAH FORECAST SOUNDING SATURDAY
EVENING. THE NAM 12 AND GFS ARE SIMILAR WITH MOISTURE VALUES
AROUND 1.60". BOTH THE GFS AND NAM FORECAST SOUNDINGS DO HAVE A
DRY LAYER AROUND THE 700 MB AREA. AS OF NOW THE AMOUNT OF DRY AIR
DOES NOT APPEAR TO BE TO GREAT FOR STORM FORMATION. FORECAST
SOUNDINGS ALSO ERODE THE CAP SATURDAY AFTERNOON. THIS WOULD IN
GENERAL MAKE SENSE GIVEN THE MID- LEVEL COOLING EXPECTED WITH THE
UPPER LEVEL LOW. WITH THE 850 MB SOUTHWESTERLY FLOW THOUGH THIS
MIGHT BE TOUGH. MODEL QPF FIELDS HAVE ALSO BEEN HINTING AT A
SECONDARY QPF BULLS EYE OUT AHEAD OF A MAIN LINE. THIS IS MOST
LIKELY FROM DISCRETE CELLS IN ASSOCIATION WITH THE WARM CONVEYOR
BELT. GIVEN THE ABOVE STRONG TO SEVERE STORMS CERTAINLY SEEMS
POSSIBLE. THE DISCRETE CELLS OUT AHEAD OF THE MAIN LINE COULD HAVE
SOME ISOLATED TORNADOES WITH WIND DAMAGE. THE MAIN LINE IS
CURRENTLY PROGGED TO MOVE THROUGH LATE SATURDAY EVENING. THE LINE
MIGHT HAVE TROUBLE HOLDING TOGETHER IN THE SOUTHWEST WHERE THE CAP
WILL BE STRONGER BUT WILL WAIT FOR FUTURE MODEL RUNS TO HELP
NARROW THESE FINE DETAILS DOWN. STRONG TO DAMAGING WINDS WITH
EMBEDDED TORNADOES WILL BE POSSIBLE IF STORMS DO END UP GOING
LINEAR. DUE TO THE MENTIONED ABOVE SPC HAS NOW INCLUDED SOUTHEAST
TEXAS IN SLIGHT RISK FOR DAY 3.
BEHIND THIS SYSTEM HIGH PRESSURE WILL MOVE SOUTHWARDS FILTERING
COOLER AIR IN ITS WAKE. MONDAY AND TUESDAY MORNING TEMPERATURES
WILL BE IN THE LOWER TO MID 30S WITH HIGHS IN THE 50S. CHRISTMAS
LOOKS TO BE NEAR NORMAL AS HIGH PRESSURE PULLS OFF TO THE EAST. 23
MARINE...
ONSHORE WINDS WILL CONTINUE TO STRENGTHEN AS LOW PRESSURE
INTENSIFIES OVER THE WESTERN HIGH PLAINS. WARMER AIR MOVING
OVER THE COOLER SHELF WATERS MAY PRODUCE SOME SEA FOG AT TIMES
BUT THE WATER TEMPS ARE WARMING A BIT SO THERE IS SOME UNCERTAINTY
WHEN/IF FOG DEVELOPS. WARMER AIR FLOWING OVER COOLER WATER ALSO TENDS
TO LIMIT MIXING SO HAVE LOWERED WIND SPEEDS OVER THE NEARSHORE WATERS.
A WEAK COLD FRONT WILL STALL OVER NORTH TEXAS ON FRIDAY AND THE
GRADIENT WILL WEAKEN. SLIGHTLY LOWER WIND SPEEDS ARE EXPECTED FRIDAY.
THE RESPITE WILL BE SHORT LIVED AS THE GRADIENT TIGHTENS SIGNIFICANTLY
FRIDAY NIGHT AND SATURDAY AND STRONG ONSHORE WINDS ARE EXPECTED. A
SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED OVER THE OFFSHORE WATERS.
A COLD FRONT WILL CROSS THE COASTAL WATERS ON SUNDAY WITH STRONG
OFFSHORE WINDS DEVELOPING BY SUNDAY EVENING. STRONG WINDS WILL PERSIST
SUNDAY NIGHT AND MONDAY WITH A SMALL CRAFT ADVISORY LIKELY. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 72 64 76 68 77 / 20 20 30 40 70
HOUSTON (IAH) 73 65 78 68 78 / 20 20 30 30 60
GALVESTON (GLS) 69 63 72 63 74 / 20 20 20 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 6 PM CST THIS EVENING
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM
FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS
FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...39
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
542 AM CST THU DEC 19 2013
.DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
&&
.AVIATION...
MADE A FEW CHANGES TO THE TAFS AS MOISTURE RETURN IS A BIT MORE
AGGRESSIVE. RADAR IS ALREADY SHOWING LIGHT RAIN ALONG THE COAST.
FCST SOUNDINGS SHOW CIGS GRADUALLY LOWERING THROUGH THE DAY AND
THE SOUNDINGS BECOME SATURATED BETWEEN 900 AND 800 MB. SOUNDINGS
ARE STRONGLY CAPPED BUT FEEL STREAMER SHOWERS WILL PERSIST THROUGH
THE AFTN. CIGS SHOULD LOWER FURTHER OVERNIGHT AND LIFR CONDS
POSSIBLE BY FRI MORNING. VERY STRONG WINDS OFF THE SURFACE SHOULD
MIX DOWNWARD TODAY SO WILL MAINTAIN GUSTS THIS AFTN. NAM12 SHOWS
45 KNOTS AT 850 MB THIS AFTN SO MAYBE WINDS NEED TO BE NUDGED
UPWARD. 43
&&
.PREV DISCUSSION... /ISSUED 440 AM CST THU DEC 19 2013/
DISCUSSION...
LOW LIGHT SATELLITE SHOWING MOSTLY CLOUDY SKIES ACROSS SOUTHEAST
TEXAS THIS MORNING. RADAR IS ALSO STARTING TO PICK UP VERY LIGHT
RETURNS OVER THE COASTAL WATERS TO THE SOUTHWEST. NAM 12 SHOWING
SOME LIGHT PVA CURRENTLY MOVING OVER THE SOUTHWESTERN AREAS. KCRP
SOUNDING ALSO SHOWS A PRETTY THICK SATURATED LAYER. THE PVA WEDGE
WILL CONTINUE TO PUSH TOWARDS THE NORTHEAST DURING THE DAY TODAY
AND IN COMBINATION WITH THE WAA THINK LIGHT STREAMER SHOWERS AND
DRIZZLE WILL BE POSSIBLE. HIGH RES HRRR AND TEXAS TECH WRF ALSO
SUPPORT THIS. THIS TREND OF LIGHT SHOWERS UNDERNEATH THE CAP WILL
PERSIST TODAY AND FRIDAY AHEAD OF THE NEXT UPPER LEVEL SYSTEM.
AS HAS BEEN ADVERTISED THE LAST COUPLE OF DAYS A SHORTWAVE IS
CURRENTLY DIVING SOUTHWARDS FROM THE PACIFIC NORTHWEST. THIS
ENERGY WILL EVENTUALLY WRAP UP INTO AN UPPER LEVEL LOW OVER THE
BAJA OF CALIFORNIA. THE UPPER LEVEL LOW WILL THEN TRACK EASTWARDS
AND EJECT OFF TOWARDS THE NORTHEAST OVER THE TEXAS PANHANDLE.
MODELS ARE STILL SHOWING THE LOW TO GAIN A NEGATIVE TILT TO IT.
UPPER LEVEL DYNAMICS APPEAR TO BE MORE FAVORABLE AGAIN FOR
SATURDAY AS THE ECMWF... GFS... CANADIAN... AND NAM 12 ALL PUT
SOUTHEAST TEXAS IN THE RRQ. SHEAR VALUES REMAIN IMPRESSIVE. 30 KTS
OR GREATER OF SFC TO 1KM SHEAR (SRH ~220 M2/S2) CAN BE FOUND IN
MOST FORECAST SOUNDINGS WITH MODEST CAPE VALUES. WHAT REMAINS TO
BE IN QUESTION IS HOW MUCH DRY AIR AND CAPPING SOUTHEAST TEXAS
WILL HAVE. ECMWF FORECAST SOUNDINGS ARE BY FAR THE MOST MOIST WITH
PWATS APPROACHING 2.00" IN THE IAH FORECAST SOUNDING SATURDAY
EVENING. THE NAM 12 AND GFS ARE SIMILAR WITH MOISTURE VALUES
AROUND 1.60". BOTH THE GFS AND NAM FORECAST SOUNDINGS DO HAVE A
DRY LAYER AROUND THE 700 MB AREA. AS OF NOW THE AMOUNT OF DRY AIR
DOES NOT APPEAR TO BE TO GREAT FOR STORM FORMATION. FORECAST
SOUNDINGS ALSO ERODE THE CAP SATURDAY AFTERNOON. THIS WOULD IN
GENERAL MAKE SENSE GIVEN THE MID- LEVEL COOLING EXPECTED WITH THE
UPPER LEVEL LOW. WITH THE 850 MB SOUTHWESTERLY FLOW THOUGH THIS
MIGHT BE TOUGH. MODEL QPF FIELDS HAVE ALSO BEEN HINTING AT A
SECONDARY QPF BULLS EYE OUT AHEAD OF A MAIN LINE. THIS IS MOST
LIKELY FROM DISCRETE CELLS IN ASSOCIATION WITH THE WARM CONVEYOR
BELT. GIVEN THE ABOVE STRONG TO SEVERE STORMS CERTAINLY SEEMS
POSSIBLE. THE DISCRETE CELLS OUT AHEAD OF THE MAIN LINE COULD HAVE
SOME ISOLATED TORNADOES WITH WIND DAMAGE. THE MAIN LINE IS
CURRENTLY PROGGED TO MOVE THROUGH LATE SATURDAY EVENING. THE LINE
MIGHT HAVE TROUBLE HOLDING TOGETHER IN THE SOUTHWEST WHERE THE CAP
WILL BE STRONGER BUT WILL WAIT FOR FUTURE MODEL RUNS TO HELP
NARROW THESE FINE DETAILS DOWN. STRONG TO DAMAGING WINDS WITH
EMBEDDED TORNADOES WILL BE POSSIBLE IF STORMS DO END UP GOING
LINEAR. DUE TO THE MENTIONED ABOVE SPC HAS NOW INCLUDED SOUTHEAST
TEXAS IN SLIGHT RISK FOR DAY 3.
BEHIND THIS SYSTEM HIGH PRESSURE WILL MOVE SOUTHWARDS FILTERING
COOLER AIR IN ITS WAKE. MONDAY AND TUESDAY MORNING TEMPERATURES
WILL BE IN THE LOWER TO MID 30S WITH HIGHS IN THE 50S. CHRISTMAS
LOOKS TO BE NEAR NORMAL AS HIGH PRESSURE PULLS OFF TO THE EAST. 23
MARINE...
ONSHORE WINDS WILL CONTINUE TO STRENGTHEN AS LOW PRESSURE
INTENSIFIES OVER THE WESTERN HIGH PLAINS. WARMER AIR MOVING
OVER THE COOLER SHELF WATERS MAY PRODUCE SOME SEA FOG AT TIMES
BUT THE WATER TEMPS ARE WARMING A BIT SO THERE IS SOME UNCERTAINTY
WHEN/IF FOG DEVELOPS. WARMER AIR FLOWING OVER COOLER WATER ALSO TENDS
TO LIMIT MIXING SO HAVE LOWERED WIND SPEEDS OVER THE NEARSHORE WATERS.
A WEAK COLD FRONT WILL STALL OVER NORTH TEXAS ON FRIDAY AND THE
GRADIENT WILL WEAKEN. SLIGHTLY LOWER WIND SPEEDS ARE EXPECTED FRIDAY.
THE RESPITE WILL BE SHORT LIVED AS THE GRADIENT TIGHTENS SIGNIFICANTLY
FRIDAY NIGHT AND SATURDAY AND STRONG ONSHORE WINDS ARE EXPECTED. A
SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED OVER THE OFFSHORE WATERS.
A COLD FRONT WILL CROSS THE COASTAL WATERS ON SUNDAY WITH STRONG
OFFSHORE WINDS DEVELOPING BY SUNDAY EVENING. STRONG WINDS WILL PERSIST
SUNDAY NIGHT AND MONDAY WITH A SMALL CRAFT ADVISORY LIKELY. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 72 64 76 68 77 / 20 20 30 40 70
HOUSTON (IAH) 73 65 78 68 78 / 30 20 30 30 60
GALVESTON (GLS) 69 63 72 63 74 / 20 20 20 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH THIS AFTERNOON FOR
THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA
SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND
TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
440 AM CST THU DEC 19 2013
.DISCUSSION...
LOW LIGHT SATELLITE SHOWING MOSTLY CLOUDY SKIES ACROSS SOUTHEAST
TEXAS THIS MORNING. RADAR IS ALSO STARTING TO PICK UP VERY LIGHT
RETURNS OVER THE COASTAL WATERS TO THE SOUTHWEST. NAM 12 SHOWING
SOME LIGHT PVA CURRENTLY MOVING OVER THE SOUTHWESTERN AREAS. KCRP
SOUNDING ALSO SHOWS A PRETTY THICK SATURATED LAYER. THE PVA WEDGE
WILL CONTINUE TO PUSH TOWARDS THE NORTHEAST DURING THE DAY TODAY
AND IN COMBINATION WITH THE WAA THINK LIGHT STREAMER SHOWERS AND
DRIZZLE WILL BE POSSIBLE. HIGH RES HRRR AND TEXAS TECH WRF ALSO
SUPPORT THIS. THIS TREND OF LIGHT SHOWERS UNDERNEATH THE CAP WILL
PERSIST TODAY AND FRIDAY AHEAD OF THE NEXT UPPER LEVEL SYSTEM.
AS HAS BEEN ADVERTISED THE LAST COUPLE OF DAYS A SHORTWAVE IS
CURRENTLY DIVING SOUTHWARDS FROM THE PACIFIC NORTHWEST. THIS
ENERGY WILL EVENTUALLY WRAP UP INTO AN UPPER LEVEL LOW OVER THE
BAJA OF CALIFORNIA. THE UPPER LEVEL LOW WILL THEN TRACK EASTWARDS
AND EJECT OFF TOWARDS THE NORTHEAST OVER THE TEXAS PANHANDLE.
MODELS ARE STILL SHOWING THE LOW TO GAIN A NEGATIVE TILT TO IT.
UPPER LEVEL DYNAMICS APPEAR TO BE MORE FAVORABLE AGAIN FOR
SATURDAY AS THE ECMWF... GFS... CANADIAN... AND NAM 12 ALL PUT
SOUTHEAST TEXAS IN THE RRQ. SHEAR VALUES REMAIN IMPRESSIVE. 30 KTS
OR GREATER OF SFC TO 1KM SHEAR (SRH ~220 M2/S2) CAN BE FOUND IN
MOST FORECAST SOUNDINGS WITH MODEST CAPE VALUES. WHAT REMAINS TO
BE IN QUESTION IS HOW MUCH DRY AIR AND CAPPING SOUTHEAST TEXAS
WILL HAVE. ECMWF FORECAST SOUNDINGS ARE BY FAR THE MOST MOIST WITH
PWATS APPROACHING 2.00" IN THE IAH FORECAST SOUNDING SATURDAY
EVENING. THE NAM 12 AND GFS ARE SIMILAR WITH MOISTURE VALUES
AROUND 1.60". BOTH THE GFS AND NAM FORECAST SOUNDINGS DO HAVE A
DRY LAYER AROUND THE 700 MB AREA. AS OF NOW THE AMOUNT OF DRY AIR
DOES NOT APPEAR TO BE TO GREAT FOR STORM FORMATION. FORECAST
SOUNDINGS ALSO ERODE THE CAP SATURDAY AFTERNOON. THIS WOULD IN
GENERAL MAKE SENSE GIVEN THE MID- LEVEL COOLING EXPECTED WITH THE
UPPER LEVEL LOW. WITH THE 850 MB SOUTHWESTERLY FLOW THOUGH THIS
MIGHT BE TOUGH. MODEL QPF FIELDS HAVE ALSO BEEN HINTING AT A
SECONDARY QPF BULLS EYE OUT AHEAD OF A MAIN LINE. THIS IS MOST
LIKELY FROM DISCRETE CELLS IN ASSOCIATION WITH THE WARM CONVEYOR
BELT. GIVEN THE ABOVE STRONG TO SEVERE STORMS CERTAINLY SEEMS
POSSIBLE. THE DISCRETE CELLS OUT AHEAD OF THE MAIN LINE COULD HAVE
SOME ISOLATED TORNADOES WITH WIND DAMAGE. THE MAIN LINE IS
CURRENTLY PROGGED TO MOVE THROUGH LATE SATURDAY EVENING. THE LINE
MIGHT HAVE TROUBLE HOLDING TOGETHER IN THE SOUTHWEST WHERE THE CAP
WILL BE STRONGER BUT WILL WAIT FOR FUTURE MODEL RUNS TO HELP
NARROW THESE FINE DETAILS DOWN. STRONG TO DAMAGING WINDS WITH
EMBEDDED TORNADOES WILL BE POSSIBLE IF STORMS DO END UP GOING
LINEAR. DUE TO THE MENTIONED ABOVE SPC HAS NOW INCLUDED SOUTHEAST
TEXAS IN SLIGHT RISK FOR DAY 3.
BEHIND THIS SYSTEM HIGH PRESSURE WILL MOVE SOUTHWARDS FILTERING
COOLER AIR IN ITS WAKE. MONDAY AND TUESDAY MORNING TEMPERATURES
WILL BE IN THE LOWER TO MID 30S WITH HIGHS IN THE 50S. CHRISTMAS
LOOKS TO BE NEAR NORMAL AS HIGH PRESSURE PULLS OFF TO THE EAST. 23
&&
.MARINE...
ONSHORE WINDS WILL CONTINUE TO STRENGTHEN AS LOW PRESSURE
INTENSIFIES OVER THE WESTERN HIGH PLAINS. WARMER AIR MOVING
OVER THE COOLER SHELF WATERS MAY PRODUCE SOME SEA FOG AT TIMES
BUT THE WATER TEMPS ARE WARMING A BIT SO THERE IS SOME UNCERTAINTY
WHEN/IF FOG DEVELOPS. WARMER AIR FLOWING OVER COOLER WATER ALSO TENDS
TO LIMIT MIXING SO HAVE LOWERED WIND SPEEDS OVER THE NEARSHORE WATERS.
A WEAK COLD FRONT WILL STALL OVER NORTH TEXAS ON FRIDAY AND THE
GRADIENT WILL WEAKEN. SLIGHTLY LOWER WIND SPEEDS ARE EXPECTED FRIDAY.
THE RESPITE WILL BE SHORT LIVED AS THE GRADIENT TIGHTENS SIGNIFICANTLY
FRIDAY NIGHT AND SATURDAY AND STRONG ONSHORE WINDS ARE EXPECTED. A
SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED OVER THE OFFSHORE WATERS.
A COLD FRONT WILL CROSS THE COASTAL WATERS ON SUNDAY WITH STRONG
OFFSHORE WINDS DEVELOPING BY SUNDAY EVENING. STRONG WINDS WILL PERSIST
SUNDAY NIGHT AND MONDAY WITH A SMALL CRAFT ADVISORY LIKELY. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 72 64 76 68 77 / 20 20 30 40 70
HOUSTON (IAH) 73 65 78 68 78 / 30 20 30 30 60
GALVESTON (GLS) 69 63 72 63 74 / 20 20 20 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH THIS AFTERNOON FOR
THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA
SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND
TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
307 PM CST THU DEC 19 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
AS OF MID AFTERNOON THURSDAY...AREA OF LOW PRESSURE SITUATED IN
NORTHEAST KANSAS WITH WARM FRONT EXTENDING NORTHEAST INTO SOUTHERN
IOWA AND NORTHERN ILLINOIS. INCREASING ISENTROPIC LIFT LATER THIS
EVENING AND MOISTURE TRANSPORT OVERRUNNING THE WARM FRONT WILL
SATURATE THE LOW LEVELS...ESPECIALLY AFTER 00Z. FORECAST SOUNDINGS
STILL SHOW A COMPLICATED TOP DOWN PRECIPITATION TYPE SCENARIO WITH
BOTH A WARM NOSE AND A LOSS OF ICE IN THE UPPER LEVELS. FIRST...THE
PROBABILITY OF NO ICE PRESENT SHIFTED SLIGHTLY NORTH FROM
PREVIOUS FORECAST. 19.12Z NAM AND RAP NOW SHOW THIS EXTENDING NORTH
TO JUST SHY OF THE I-90 CORRIDOR IN WISCONSIN. IT IS NOT UNTIL VERY
EARLY FRIDAY MORNING THAT ICE GETS REINTRODUCED...AND A CHANGEOVER
TO LIGHT SNOW WOULD THEN OCCUR FOR PLACES SUCH AS VIROQUA OVER TO
JUNEAU/ADAMS COUNTIES. AT THE SAME TIME...RAP SOUNDINGS FOR DBQ
SHOW MAX WARM NOSE OF +4 DEGREES...AROUND +1 FOR BLR...AND THEN
BELOW ZERO FOR AREAS TO THE NORTH. SO...TIGHT GRADIENT FOR
FREEZING RAIN AND SNOW LINE. AS FAR AS ICE ACCUMULATIONS...UP TO
1/10 OF AN INCH STILL EXPECTED ON EXPOSED SURFACES...WHICH WILL
MAKE FOR SLICK TRAVEL OVERNIGHT INTO THE MORNING HOURS FRIDAY.
GIVEN THIS NORTHWARD JOG IN THE LOSS OF ICE / WARM NOSE...HAVE
EXPANDED THE FREEZING RAIN ADVISORY TO INCLUDE VERNON...JUNEAU AND
ADAMS COUNTIES IN WISCONSIN.
THE NORTHERN SIDE OF THIS WEATHER SYSTEM STILL EXPECTED TO PRODUCE A
BAND OF ACCUMULATING SNOW ALONG AND NORTH OF I-90...MAINLY AFTER
MIDNIGHT INTO FRIDAY MORNING. NO BIG CHANGES FROM
PREVIOUS FORECAST...WITH 1 TO 2 INCHES FOR MOST LOCATIONS AND
LOCALLY 3 INCH AMOUNTS POSSIBLE MAINLY FOR CENTRAL WISCONSIN. THIS
TOO COULD MAKE FOR SLICK ROADWAYS FOR THE FRIDAY MORNING
COMMUTE...AND CONSIDERED A HEADLINE FOR THIS BUT WILL HOLD OFF NOW
GIVEN COLLABORATION. IF LATER FORECASTS SHOW AN UPTICK IN
AMOUNTS...OR A DELAY MORE TOWARD THE MORNING COMMUTE...THEN AN
WINTER WEATHER ADVISORY MAY BE NEEDED FOR A FEW COUNTIES.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
FOCUS OF THIS PERIOD IS SQUARELY ON THE WEEKEND AND THE POTENTIAL
FOR A WINTER STORM TO IMPACT PARTS OF THE FORECAST AREA. STILL
SOME DIFFERENCES BETWEEN THE MODELS BUT THE 19.12Z GFS AND ECMWF
ARE IN BETTER AGREEMENT WITH THE OVERALL PATTERN WITH THE 19.12Z
NAM APPEARING AT THIS TIME TO BE THE ODD MODEL OUT. THE UPPER
LEVEL LOW CURRENTLY ALONG THE CALIFORNIA COAST WILL MOVE OUT OF
THE DESERT SOUTHWEST AND TRACK NORTHEAST ACROSS THE CENTRAL
PORTION OF THE COUNTRY OVER THE WEEKEND. AS IT MOVES TOWARD THE
AREA...A NORTHERN STREAM SHORT WAVE WILL START TO MOVE TOWARD THE
UPPER MIDWEST FROM SOUTHWEST CANADA. THE DIFFERENCES IN THE MODEL
SOLUTIONS REVOLVE AROUND WHETHER THESE TWO SYSTEMS GET PHASED OR
WHETHER THEY STAY SEPARATE. THE NAM WOULD SUGGEST THEY GET PHASED
WHICH PUSHES THE SURFACE LOW AND ASSOCIATED QPF FARTHER SOUTHEAST.
THE GFS AND ECMWF DO NOT PHASE THE TWO SYSTEMS WHICH BRINGS THE
SURFACE LOW AND QPF BACK MORE TO THE NORTHWEST.
THE FORCING FROM THE SHORT WAVE TROUGH WILL START TO MOVE IN
SATURDAY NIGHT. MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB
LAYER SHOULD OCCUR LATE SATURDAY NIGHT JUST AHEAD OF THE WAVES
PASSAGE. MODERATE TO STRONG QG CONVERGENCE WILL BE PRODUCED BY THE
WAVE AND CENTERED OVER THE SOUTHEAST PART OF THE FORECAST AREA AT
12Z SUNDAY. WEAK TO MODERATE FRONTOGENESIS IS SHOWN BY THE GFS IN
THE 600-500 MB LAYER BETWEEN 06Z AND 18Z SUNDAY...ALSO OVER THE
SOUTHEAST PORTIONS OF THE FORECAST AREA. THERE MAY ALSO BE SOME
JET DYNAMICS THAT COME INTO PLAY AS WELL. THE GFS IS SUGGESTING A
SPLIT JET WITH THE AREA UNDER THE RIGHT ENTRANCE REGION OF THE
NORTHERN STREAM JET CORE TO ADD SOME AGEOSTROPHIC LIFT TO THE MIX.
THE GFS BUFKIT SOUNDING FOR BLUE RIVER SUGGEST THE DENDRITIC
GROWTH ZONE SHOULD BE ABOUT 100 MB DEEP WITH GOOD VERTICAL MOTIONS
THROUGH IT. THIS SHOULD LEAD TO SNOW RATIOS IN THE 14-16 TO 1
RANGE LEADING TO SNOW ACCUMULATIONS OF 4 TO 7 INCHES FROM ABOUT
FAYETTE COUNTY IOWA NORTHEAST INTO ADAMS/JUNEAU COUNTIES IN
CENTRAL WISCONSIN. THE POTENTIAL FOR THE HIGHER AMOUNTS IS THE
GREATEST IN PRIMARILY GRANT COUNTY WISCONSIN. THE NORTHWEST WINDS
WILL COME UP SUNDAY ON THE BACK SIDE OF THE SYSTEM WHICH WILL
LIKELY LEAD TO SOME DRIFTING SNOW AND POSSIBLY A LITTLE BLOWING
SNOW OVER THE MORE OPEN AREAS OF NORTHEAST IOWA. IN COORDINATION
WITH SURROUNDING OFFICES...WILL ISSUE A WINTER STORM WATCH FOR
SATURDAY NIGHT AND SUNDAY FOR THE ACCUMULATING SNOW AND ANY
POSSIBLE IMPACT ON THE BACK SIDE OF THE SYSTEM.
WITH THE FOCUS ON THE WEEKEND SYSTEM...HAVE NOT LOOKED EXTENSIVELY
AT THE FORECAST FOR NEXT WEEK. HAVE LET THE MODEL CONSENSUS GRIDS
RIDE WHICH GIVES A SMALL CHANCE FOR SOME SNOW TUESDAY AND TUESDAY
NIGHT ACROSS THE NORTH AS ANOTHER NORTHERN STREAM SHORT WAVE
TROUGH MOVES ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION. THE
COLDEST TEMPERATURES IN THE FORECAST LOOK TO BE BEHIND THE WEEKEND
SYSTEM WITH LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO SUNDAY
NIGHT...HIGHS ONLY IN THE SINGLE DIGITS ABOVE ZERO MONDAY WITH
SINGLE DIGITS BELOW ZERO FOR THE ENTIRE AREA MONDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1124 AM CST THU DEC 19 2013
INCREASING MOISTURE DURING THE AFTERNOON WILL LEAD TO A GRADUAL
LOWERING OF THE CEILINGS AT KRST/KLSE...DETERIORATING MID EVENING
AS LOW LEVEL MOISTURE REALLY RAMPS UP. TRENDS IN THE FORECAST
SUGGEST A LITTLE LATER START TO PRECIPITATION...SO HAVE ADJUSTED
ONSET TIME A FEW HOURS. OTHERWISE...STILL EXPECTING SNOW TO THE
PREDOMINANT PRECIPITATION TYPE THOUGH THE FREEZING DRIZZLE/RAIN
WILL BE JUST A FEW COUNTIES TO THE SOUTH...ESPECIALLY FOR KLSE.
THE BULK OF THE PRECIPITATION LOOKS TO BE IN THE 06-12Z
TIMEFRAME...THEN TAPERING OFF FRIDAY MORNING. TOTAL AMOUNTS SHOULD
BE IN THE 1 TO MAYBE 2 INCH RANGE. LOW LEVEL MOISTURE HANGS
AROUND MUCH OF FRIDAY...SO HAVE KEPT RESTRICTIVE CEILINGS IN
PLACE THROUGH 18Z. VISIBILITIES ARE EXPECTED TO LOWER TO IFR
AFTER MIDNIGHT DURING THE PEAK OF THE LIGHT SNOW...IMPROVING TO
VFR BY 12Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 6 AM CST FRIDAY FOR WIZ043-044-
053>055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053>055-061.
MN...NONE.
IA...FREEZING RAIN ADVISORY UNTIL 6 AM CST FRIDAY FOR IAZ010-011-019-
029-030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029-030.
&&
$$
SHORT TERM...ZT
LONG TERM...04
AVIATION...ZT
AREA FORECAST DISCUSSION
NWS ALBANY NY
222 AM EST SAT DEC 21 2013
.SYNOPSIS...
A SERIES OF LOW PRESSURE WAVES WILL PROPAGATE ALONG A NEARLY
STATIONARY FRONT FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK
AND NORTHERN NEW ENGLAND THROUGH TONIGHT. A MUCH STRONGER STORM
WILL MOVE OUT OF THE OHIO VALLEY SUNDAY ALONG THIS FRONT. IN ITS
WAKE COLDER AIR WILL FILER BACK INTO THE REGION FOR THE FIRST HALF
OF THE WEEK. THE WEEKEND WILL FEATURE MILD TEMPERATURES FOR
DECEMBER...PERIODS OF RAIN BECOMING WIDESPREAD LATE SATURDAY INTO
SUNDAY WITH FREEZING RAIN ALONG THE NORTHERN TIER OF NEW YORK AND
NEW ENGLAND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1218 AM EST...BATCH OF RAIN IS NOW EXITING SOUTHERN
VERMONT...WITH JUST VERY LIGHT SPRINKLES AND RAIN SHOWERS
REMAINING OVER EASTERN NY. THIS LOOKS TO BE A BREAK IN THE
PRECIP...AS DEPICTED BY THE HRRR AND LOCAL HIRES WRF. ADDITIONAL
RAINFALL...NOTED ON THE REGIONAL MOSAIC RADAR ACROSS WESTERN NEW
YORK...WILL BE APPROACHING FOR THE LATE OVERNIGHT HOURS...SO WILL
CONTINUE WITH RATHER HIGH POPS ACROSS NORTHERN PARTS OF THE AREA.
TEMPERATURES ARE STILL ABOVE FREEZING ACROSS MUCH OF THE AREA
EXCEPT FOR A LIMITED AREA OF FAR NORTHERN WARREN AND WASHINGTON
COUNTIES WHERE NORTHERLY WINDS HAVE ALLOWED COLD AIR TO DRAIN
SOUTHWARD THROUGH THE CHAMPLAIN VALLEY TO THE LAKE GEORGE REGION.
TEMPS IN THE NORTHERN PART OF THE LAKE GEORGE AREA ARE IN THE MID
TO UPPER 20S...WITH LOW TO MID 30S ACROSS SOUTHERN PARTS OF THE
LAKE. A FREEZING RAIN ADVISORY REMAINS IN EFFECT THERE THROUGH 6
AM. WILL CONTINUE TO MENTION UP TO ONE TENTH OF AN INCH OF ICE IN
THIS SMALL AREA. TEMPS SHOULD GRADUALLY WARM UP THROUGH THE NIGHT
IN THIS AREA. FOR SOME AREAS WHERE MIXING HAS BEEN ABLE TO
OCCUR...TEMPS HAVE RISEN INTO THE LOWER TO MID 40S. TEMPERATURES
ARE GENERALLY EXPECTED TO REMAIN STEADY THROUGH THE NIGHT FOR THE
REMAINDER OF THE AREA.
STRONGER UPPER LEVEL ENERGY...FORCING AND MOISTURE ADVECTION
APPROACHES SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. HEAVIER
RAINFALL SHOULD SPREAD ACROSS THE REGION SATURDAY AFTERNOON AND
NIGHT...WITH THE HEAVIEST RAIN OCCURRING SATURDAY NIGHT INTO EARLY
SUNDAY. THERE ARE CONSIDERABLE DISAGREEMENTS IN SOURCES OF GUIDANCE
AND ENSEMBLES AS TO HOW MUCH COLDER AIR SINKS SOUTH SATURDAY NIGHT
IN RESPONSE TO ENHANCED UPPER CONFLUENCE IN CANADA AS UPPER ENERGY
TRACKS WELL NORTH OF THE U.S. CANADIAN BORDER. ENOUGH COLD AIR COULD
SINK SOUTHWARD AGAIN SATURDAY NIGHT TO PRODUCE SOME FREEZING RAIN.
MODELS INDICATE THAT ANY PERIOD OF NEAR OR BELOW FREEZING TEMPS
ALONG THE NORTHERN BORDER OF THE FORECAST AREA WOULD BE BRIEF AND
ONLY PRODUCE LIGHT ICING AMOUNTS (UNDER A QUARTER OF AN INCH). NO
WINTER STORM WATCH WILL BE ISSUED AND IF APPEARS MORE CERTAIN THAT
SOME FREEZING RAIN WILL FALL LATE SATURDAY NIGHT...THEN ADVISORIES
CAN BE ISSUED ON SATURDAY.
A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...ALONG
WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY RAIN EVENT...AND
COMBINED WITH SNOW MELT...COULD RESULT IN SOME FLOODING POTENTIAL.
THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL FORECASTS FROM SOURCES
OF GUIDANCE AND ENSEMBLES STILL INDICATE THAT A BROAD RANGE AND AXIS
OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM SNOW MELT OCCURS.
A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY RESULTS IN THE
HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH AGAIN MAY SEE THE
LEAST WARM TEMPERATURES AND LEAST SNOW MELT. SO...STILL HOLDING OFF
ON ANY FLOOD WATCHES.
HIGHS SATURDAY IN THE 40S TO LOWER 50S...LOWS SATURDAY IN THE 40S
OVER THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA...AND 30S NORTH.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
BY SUNDAY MORNING STATIONARY FRONT REMAINS DRAPED FROM SW NYS TO
NR PWM. OVERRUNNING HAD BEEN THE PRIMARY DRIVER OF UVM AND PCPN
THROUGH SAT NT ALONG WITH AGEO CIRC ASSOC WITH RIGHT ENTRANCE RGN
OF INTENSE 300HPA JET. RAINS WILL HAVE OVERSPREAD THE ENTIRE FCA
MUCH OF THE NIGHT. BY SUN MRNG GFS HAS OVER 2 IN QPF IN ADIRONDACKS
TO LESS THAN 1 TENTH IN MID HUD VLY WITH A SOMEWHAT MORE GENEROUS
MAX IN THE NAM OF 2.6 IN.
SUNDAY A SHARP SHORT WV EJECTS INTO THE UPR MIDWEST...TRIGGERING A
MUCH DEEPER CYCLOGENISUS IN THE OHIO VLY THAN THE WAVES THAT HAD
BEEN RIPPLING ALONG THE STATIONARY FRONT TO THIS POINT. THE LOW
DEEPENS AS IT MOVES ACROSS FCA SUN. IN ADDITION THE PREVIOUSLY ACTING
ISENTROPIC LIFT AND JET DYNAMICS...CONVERGENCE WITH THE LOW AND
ALONG THE WMFNT WILL ENHANCE A BURST OF PCPN SUN WORKING WITH RICH
AIR MASS AND PW OF 1.25 IN OR BETTER.
SUNDAY THE MDLS DUMP ANOTHER TENTH OF AN INCH QPF IN MID HUD VLY
WITH ANOTHER TO 1.25 INCHES IN ADRNDKS. THE GEM HAS SIMILAR
NUMBERS WITH A MAX SHIFTED SLIGHTLY TO THE N OF US MDLS AND A
FRONTAL POSITION 50 OR SO MILES N.
IN SUMMARY QPF VALUES FM DETERMINISTIC MDLS ARE ANOTHER 0.5 TO 1.0
INCHES GREATER THAN PVS QPF. TOTALS ARE ON THE ORDER FROM 0.25 MID
HUD VLY TO 3 PLUS INCHES IN ADRNDKS. THE ECMWF AND GEM ARE ON THE
LIGHTER SIDE WITH A MAX QPF CLOSER TO 2 INCHES TOTAL. ADD TO THAT
THE SNOW PACK MELT. BY SUNDAY SNOW PACK WILL BE RIPE OR RIPENING
N. MOST WILL BE GONE IN THE SE. IN THE SE 1.0 LIQ OF SNOW PACK AND
A HALF AN INCH OF QPF SHOULDN`T PUSH RIVERS OUT OF THEIR BANKS.
HWVR FURTHER N...COLDER TEMPS EARLIER IN THE PERIOD HAVE SLOWED
SNOW MELT...WILL GIVE WAY TO 40S SUN WITH 2-3 INCHES OF QPF..AND
MAYBE AN INCH OF SNOW MELT.
AT THIS POINT AN LEANING TWRD A FLOOD WATCH FOR SAT NT THROUGH SUN...WITH
2-3 IN QPF N TIER...AN INCH OF SNOW MELT. POTENTIAL FOR WIDESPREAD
MINOR FLOODING INCRG.
BY SUN NT SFC LOW EXISTS NY INTO N NEW ENG AND DRY SLOT MOVES INTO
RGN. RN SHOULD DIM TO SCT -SHRA BUT TEMPS WILL REMAIN ABV FREEZING
ACROSS MOST AREA...AND SNOW MELT AND RUNOFF WILL CONTINUE.
DURING SUNDAY AND SUN NT TEMPS ARE EITHER NON DIURNAL OR MAV/MET
MAX MIN VALUES ARE 24 HRS VALUES FM SAT AND WILL USE 3 HRLY TEMPS
MONDAY THE SFC LOW AND ITS CDFNT MOVE EAST OF RGN. AND DURING MON
AND TUE CAA AND INCRG WIND GRADIENT WILL BE THE RULE AS TEMPS
RETURN TO NR OR BLO NORMAL TUES.
MON FCA WILL BE IN DRY SLOT WITH VERY GRADUAL CAA. HWVR AT 500HPA
MAJOR TROF IS BEING CARVED OUT OVER GRTLKS AS SERIES OF SHORT WVS
DIG S INTO IT. MONDAY NGT AND TUES THE 500HPA TROF MOVES ACROSS
FCA WITH MUCH STRONGER CDFNT AND BRISK N-NE WINDS IN ITS WAKE.
CDFNT PASSAGE WILL TRIGGER SCT -SHSN MON NT...BUT H850 AND LLVL FLOW
NOT FAVORABLE FOR LK RESPONSE IN FCA TUE. TUES AND CHRISTMAS TEMPS
WILL BE SVRL DEG BLO NORMAL AS SFC HIGH BEGINS BUILDING SE FM
OTTAWA VLY. 500HPA TROF MAY STILL BE SUF TO TRIGGER SCT INSTAB
-SHSN TUES AND TUE NT. SKIES WILL BE PC WITH MORE CLOUDS N AND
FEWER S MON-TUE. CHRISTMAS DAY SHOULD BE BRIGHTER AND SUNNY AS SFC
HIGH CRESTS OVER THE REGION, HWVR IT WILL START ON THE FRIGID SIDE
AS CLR SKIES ON SOME OF THE LONGEST NIGHTS OF THE YEAR WILL ALLOW
IDEAL RADIATIONAL COOLING. MEX LOWS AT SLK ARE -19F TO +10 AT
POU.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
DRY CONDITIONS SHOULD PERSIST WEDNESDAY NIGHT...ALTHOUGH A BIT OF
A SOUTHERLY GRADIENT DEVELOPS AROUND THE DEPARTING HIGH WHICH
COULD ALLOW FOR MILDER TEMPERATURES DEPENDING ON THE AMOUNT OF
MIXING AT NIGHT.
THE FORECAST BECOMES A BIT MORE MURKY FROM THURSDAY INTO FRIDAY...AS
ENERGY ASSOCIATED WITH AN UPPER LEVEL TROUGH MOVES EASTWARD ACROSS
THE GREAT LAKES...WHILE THERE IS THE POTENTIAL FOR A SOUTHERN STREAM
DISTURBANCE TO PHASE WITH THE PRIMARY TROUGH. THE ECMWF IS MOST
AGGRESSIVE WITH THIS SCENARIO...WHICH COULD LEAD TO A MORE
WIDESPREAD MODERATE PRECIP EVENT. THE GFS IS MUCH MORE PROGRESSIVE
THOUGH...SO WILL CONSERVATIVELY MENTION LOW CHANCE POPS AT THIS TIME.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
IFR CONDITIONS DUE TO RAIN AND FOG CONTINUE TO KGFL AND THIS LOOKS
TO CONTINUE FOR THE REMAINDER OF THE OVERNIGHT HOURS.
MEANWHILE...VFR CONDITIONS ARE IN PLACE FOR THE OTHER REMAINING
TAF SITES...WITH CIGS GENERALLY 4-8 KFT. CIGS WILL GRADUALLY
LOWER TO MVFR FOR KALB/KPSF TOWARDS DAYBREAK...ESP AS THE NEXT
BATCH OF RAIN CURRENTLY OVER WESTERN NY APPROACHES THE REGION.
KPSF/KPOU SHOULD BE ABLE TO AVOID MOST OF THIS NEXT BATCH OF
RAIN...WITH MAINLY KGFL/KALB TO BE IMPACTED.
DURING THE DAY SATURDAY...CONDITIONS WILL LOWER TO IFR FOR ALL
SITES WITH RAIN...MIST...AND LOW STRATUS CLOUDS. IT MAY TAKE
UNTIL LATE IN THE DAY FOR THE RAIN TO REACH KPOU. THE STEADIEST
AND HEAVIEST RAIN LOOKS TO OCCUR SAT EVENING INTO SAT NIGHT.
LLWS WILL BE IN PLACE THROUGH MUCH OF THE TAF PERIOD WITH 2 KFT
WINDS AROUND 35-40 KTS OUT OF THE WEST-SOUTHWEST. MEANWHILE...SFC
WINDS WILL BE MAINLY LIGHT OVERNIGHT INTO THE DAY SATURDAY...BECOMING
SOUTHERLY AT 10 KTS OR LESS. LLWS SHOULD END BY SAT AFTN AS THE
BEST LOW LEVEL JET SHIFTS AWAY FROM THE AREA.
OUTLOOK...
SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA.
SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN.
TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE
WEEKEND...WHICH MEANS SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A
STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY
EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL
AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD
COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH.
BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM
TEMPERATURES...SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS
ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD
BE MELTED FROM ABOUT THE MOHAWK RIVER SOUTH. FURTHER NORTH...
TEMPERATURES MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW.
THE POTENTIAL IS THERE FOR 1-2.5 INCHES OF RAINFALL FROM ALBANY
NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESSER AMOUNTS OF
RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS.
WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
NYZ042-043.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...GJM/SNYDER
NEAR TERM...FRUGIS/GJM/JPV
SHORT TERM...SNYDER
LONG TERM...JPV
AVIATION...FRUGIS
HYDROLOGY...GJM/NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1218 AM EST SAT DEC 21 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM THE GREAT LAKES THROUGH NORTHERN
NEW YORK AND NORTHERN NEW ENGLAND WILL PRODUCE SCATTERED LIGHT
PRECIPITATION TONIGHT. THE FRONT WILL SINK SOUTH AS A COLD FRONT
INTO PARTS OF CENTRAL NEW YORK AND SOUTHERN VERMONT BY SATURDAY
NIGHT...SUPPORTING CHANCES FOR FREEZING RAIN IN THE NORTH COUNTRY.
STRONG LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE TENNESSEE AND
OHIO VALLEY SUNDAY AS THE FRONT SURGES NORTH INTO CANADA.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1218 AM EST...BATCH OF RAIN IS NOW EXITING SOUTHERN
VERMONT...WITH JUST VERY LIGHT SPRINKLES AND RAIN SHOWERS
REMAINING OVER EASTERN NY. THIS LOOKS TO BE A BREAK IN THE
PRECIP...AS DEPICTED BY THE HRRR AND LOCAL HIRES WRF. ADDITIONAL
RAINFALL...NOTED ON THE REGIONAL MOSAIC RADAR ACROSS WESTERN NEW
YORK...WILL BE APPROACHING FOR THE LATE OVERNIGHT HOURS...SO WILL
CONTINUE WITH RATHER HIGH POPS ACROSS NORTHERN PARTS OF THE AREA.
TEMPERATURES ARE STILL ABOVE FREEZING ACROSS MUCH OF THE AREA
EXCEPT FOR A LIMITED AREA OF FAR NORTHERN WARREN AND WASHINGTON
COUNTIES WHERE NORTHERLY WINDS HAVE ALLOWED COLD AIR TO DRAIN
SOUTHWARD THROUGH THE CHAMPLAIN VALLEY TO THE LAKE GEORGE REGION.
TEMPS IN THE NORTHERN PART OF THE LAKE GEORGE AREA ARE IN THE MID
TO UPPER 20S...WITH LOW TO MID 30S ACROSS SOUTHERN PARTS OF THE
LAKE. A FREEZING RAIN ADVISORY REMAINS IN EFFECT THERE THROUGH 6
AM. WILL CONTINUE TO MENTION UP TO ONE TENTH OF AN INCH OF ICE IN
THIS SMALL AREA. TEMPS SHOULD GRADUALLY WARM UP THROUGH THE NIGHT
IN THIS AREA. FOR SOME AREAS WHERE MIXING HAS BEEN ABLE TO
OCCUR...TEMPS HAVE RISEN INTO THE LOWER TO MID 40S. TEMPERATURES
ARE GENERALLY EXPECTED TO REMAIN STEADY THROUGH THE NIGHT FOR THE
REMAINDER OF THE AREA.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
STRONGER UPPER LEVEL ENERGY...FORCING AND MOISTURE ADVECTION
APPROACHES SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. HEAVIER
RAINFALL SHOULD SPREAD ACROSS THE REGION SATURDAY AFTERNOON AND
NIGHT...WITH THE HEAVIEST RAIN OCCURRING SATURDAY NIGHT INTO EARLY
SUNDAY. THERE ARE CONSIDERABLE DISAGREEMENTS IN SOURCES OF GUIDANCE
AND ENSEMBLES AS TO HOW MUCH COLDER AIR SINKS SOUTH SATURDAY NIGHT
IN RESPONSE TO ENHANCED UPPER CONFLUENCE IN CANADA AS UPPER ENERGY
TRACKS WELL NORTH OF THE U.S. CANADIAN BORDER. ENOUGH COLD AIR COULD
SINK SOUTHWARD AGAIN SATURDAY NIGHT TO PRODUCE SOME FREEZING RAIN.
MODELS INDICATE THAT ANY PERIOD OF NEAR OR BELOW FREEZING TEMPS
ALONG THE NORTHERN BORDER OF THE FORECAST AREA WOULD BE BRIEF AND
ONLY PRODUCE LIGHT ICING AMOUNTS (UNDER A QUARTER OF AN INCH). NO
WINTER STORM WATCH WILL BE ISSUED AND IF APPEARS MORE CERTAIN THAT
SOME FREEZING RAIN WILL FALL LATE SATURDAY NIGHT...THEN ADVISORIES
CAN BE ISSUED ON SATURDAY.
A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...ALONG
WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY RAIN EVENT...AND
COMBINED WITH SNOW MELT...COULD RESULT IN SOME FLOODING POTENTIAL.
THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL FORECASTS FROM SOURCES
OF GUIDANCE AND ENSEMBLES STILL INDICATE THAT A BROAD RANGE AND AXIS
OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM SNOW MELT OCCURS.
A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY RESULTS IN THE
HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH AGAIN MAY SEE THE
LEAST WARM TEMPERATURES AND LEAST SNOW MELT. SO...STILL HOLDING OFF
ON ANY FLOOD WATCHES.
HIGHS SATURDAY IN THE 40S TO LOWER 50S...LOWS SATURDAY IN THE 40S
OVER THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA...AND 30S NORTH.
HIGHS SUNDAY 45 TO 55 NORTH...AND 55 TO 65 SOUTH. LOWS SUNDAY NIGHT
IN THE 40S SOUTH...30S NORTH.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE PERIOD STARTS OUT ON MONDAY WITH COLDER AIR GRADUALLY FILTERING
INTO THE REGION WITH A WSW FLOW BECOMING WNW. A FRONTAL BOUNDARY TO
OUR SOUTH OVER THE MID ATLANTIC REGION IS FORECAST TO STALL...WITH A
WAVE OF LOW PRESSURE MOVING NORTHEASTWARD ALONG THE FRONT. SOME
LIGHT RAIN ASSOCIATED WITH THIS WAVE COULD AFFECT AREAS MAINLY SOUTH
AND EAST OF ALBANY. THE GFS/ECMWF HAS SOME LIGHT QPF JUST SCRAPING
OUR SOUTHEAST ZONES...WHILE THE NAM IS MOST AGGRESSIVE WITH BRINGING
THE WAVE AND ASSOCIATED QPF NORTHWARD. WILL MENTION CHANCE POPS FOR
NOW...WITH ANOTHER AREA OF CHANCE POPS ACROSS NORTHWEST AREAS DUE TO
SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS DEVELOPING.
TEMPERATURES SHOULD DROP SIGNIFICANTLY MONDAY NIGHT INTO CHRISTMAS
EVE MORNING...AS STRONG COLD ADVECTION COMMENCES. THE FLOW
TRAJECTORY IS FORECAST TO SHIFT TO THE NORTHWEST...SO SOME
MULTI-BAND LAKE EFFECT SNOW SHOWERS COULD IMPACT THE MOHAWK AND
SCHOHARIE VALLEY...AS WELL AS THE NORTHERN CATSKILLS CHRISTMAS EVE
DAY. CHRISTMAS EVE NIGHT THROUGH CHRISTMAS DAY LOOKS TO BE DRY BUT
COLD REGION-WIDE...AS HIGH PRESSURE BUILDS IN THEN SHIFTS EASTWARD
INTO NEW ENGLAND BY LATE CHRISTMAS DAY. DRY CONDITIONS SHOULD
PERSIST WEDNESDAY NIGHT...ALTHOUGH A BIT OF A SOUTHERLY GRADIENT
DEVELOPS AROUND THE DEPARTING HIGH WHICH COULD ALLOW FOR MILDER
TEMPERATURES DEPENDING ON THE AMOUNT OF MIXING AT NIGHT.
THE FORECAST BECOMES A BIT MORE MURKY FROM THURSDAY INTO FRIDAY...AS
ENERGY ASSOCIATED WITH AN UPPER LEVEL TROUGH MOVES EASTWARD ACROSS
THE GREAT LAKES...WHILE THERE IS THE POTENTIAL FOR A SOUTHERN STREAM
DISTURBANCE TO PHASE WITH THE PRIMARY TROUGH. THE ECMWF IS MOST
AGGRESSIVE WITH THIS SCENARIO...WHICH COULD LEAD TO A MORE
WIDESPREAD MODERATE PRECIP EVENT. THE GFS IS MUCH MORE PROGRESSIVE
THOUGH...SO WILL CONSERVATIVELY MENTION LOW CHANCE POPS AT THIS TIME.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
IFR CONDITIONS DUE TO RAIN AND FOG CONTINUE TO KGFL AND THIS LOOKS
TO CONTINUE FOR THE REMAINDER OF THE OVERNIGHT HOURS.
MEANWHILE...VFR CONDITIONS ARE IN PLACE FOR THE OTHER REMAINING
TAF SITES...WITH CIGS GENERALLY 4-8 KFT. CIGS WILL GRADUALLY
LOWER TO MVFR FOR KALB/KPSF TOWARDS DAYBREAK...ESP AS THE NEXT
BATCH OF RAIN CURRENTLY OVER WESTERN NY APPROACHES THE REGION.
KPSF/KPOU SHOULD BE ABLE TO AVOID MOST OF THIS NEXT BATCH OF
RAIN...WITH MAINLY KGFL/KALB TO BE IMPACTED.
DURING THE DAY SATURDAY...CONDITIONS WILL LOWER TO IFR FOR ALL
SITES WITH RAIN...MIST...AND LOW STRATUS CLOUDS. IT MAY TAKE
UNTIL LATE IN THE DAY FOR THE RAIN TO REACH KPOU. THE STEADIEST
AND HEAVIEST RAIN LOOKS TO OCCUR SAT EVENING INTO SAT NIGHT.
LLWS WILL BE IN PLACE THROUGH MUCH OF THE TAF PERIOD WITH 2 KFT
WINDS AROUND 35-40 KTS OUT OF THE WEST-SOUTHWEST. MEANWHILE...SFC
WINDS WILL BE MAINLY LIGHT OVERNIGHT INTO THE DAY SATURDAY...BECOMING
SOUTHERLY AT 10 KTS OR LESS. LLWS SHOULD END BY SAT AFTN AS THE
BEST LOW LEVEL JET SHIFTS AWAY FROM THE AREA.
OUTLOOK...
SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA.
SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN.
TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE
WEEKEND...WHICH MEANS SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A
STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY
EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL
AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD
COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH.
BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM
TEMPERATURES...SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS
ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD
BE MELTED FROM ABOUT THE MOHAWK RIVER SOUTH. FURTHER NORTH...
TEMPERATURES MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW.
THE POTENTIAL IS THERE FOR 1-2.5 INCHES OF RAINFALL FROM ALBANY
NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESSER AMOUNTS OF
RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS.
WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
NYZ042-043.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...GJM
NEAR TERM...FRUGIS/GJM/JPV
SHORT TERM...GJM
LONG TERM...JPV
AVIATION...FRUGIS
HYDROLOGY...GJM/NAS
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
340 AM EST SAT DEC 21 2013
.SYNOPSIS...
HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY
MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD
FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY.
COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON
THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING SHOULD
HELP SUPPORT CONSIDERABLE STRATUS AND FOG EARLY THIS MORNING.
STRATUS SHOULD BE FAVORED BECAUSE OF SIGNIFICANT BOUNDARY-LAYER
WIND. HEATING AND MIXING LATER THIS MORNING SHOULD HELP DIMINISH
SOME OF THIS CLOUDINESS...BUT CLOUDINESS SHOULD LINGER THROUGH
THE DAY BECAUSE OF ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL
MOISTURE STREAMING INTO THE AREA IN THE SOUTHWEST FLOW. GENERALLY
EXPECT PARTLY CLOUDY OR MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK
AND MOISTURE SHALLOW WITH FORCING ASSOCIATED WITH THE FRONT WELL
TO THE WEST. THE SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION
MODELS KEEP THE FORECAST AREA DRY. THE NAM...GFS AND ECMWF MOS
INDICATE POPS OF 20 PERCENT OR LESS. IT WILL BE WARM AND THE
TEMPERATURE GUIDANCE WAS CONSISTENT DISPLAYING HIGHS IN THE MIDDLE
AND UPPER 70S WHICH WILL BE 15 TO 20 DEGREES ABOVE NORMAL. THE
BUFKIT MOMENTUM TRANSFER TOOL AND HRRR INDICATED WIND GUSTS NEAR
20 KNOTS THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE
OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP
ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS
MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE
GUIDANCE BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL
BE 20 TO 30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM
RECORDS FOR THE DATE WILL BE IN JEOPARDY.
SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT
NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES
SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW
PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF
SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION
OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40
TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY
WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE
FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY
IN THE WEST PART OF THE FORECAST AREA SUNDAY.
A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL
RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING
TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG
UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN
THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH
THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF
HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT.
THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER
FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE
UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE
VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND
EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL
SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED
TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN
WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL
FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY
BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND
THE FRONT LATER IN THE DAY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS
EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES
FOR RAIN BY THE END OF THE WEEK.
THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY
ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH
PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN
STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH
TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS
TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD MAXIMUM
TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S WHILE LOW
TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL WEDNESDAY
MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING.
DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY
THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF
A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL
INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND
ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS
THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN
POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE
WEEK SHOULD BE NEAR NORMAL.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
LOW CONFIDENCE REGARDING CIG/VSBY RESTRICTIONS LATE TONIGHT/EARLY
SATURDAY MORNING.
CLOUDS CONTINUE TO INCREASE FROM THE WEST AS WITH PATCHY FOG
BEGINNING TO FORM. LOW AND MID CLOUDS HAVE MOVED INTO EASTERN GA
WHICH WILL WORK TO LESSEN FOG POTENTIAL OVERNIGHT...HOWEVER WITH
FOG ALREADY DEVELOPING POTENTIAL FOR FOG REMAINS MODERATE AND THUS
CONFIDENCE REMAINS LOW DUE TO TIMING ISSUES. HAVE REMAINED WITH
MVFR FOG FOR CAE/CUB/DNL WITH IFR/LIFR FOR AGS/OGB. FOG WILL ERODE
WITH SUNRISE AND ONSET OF MIXING WITH REMAINDER OF THE PERIOD VFR.
WINDS WILL BE LIGHT AND VARIABLE THROUGH MID MORNING THEN BECOME
SOUTHWESTERLY AROUND 10 KNOTS THROUGH THE END OF THE PERIOD.
EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS
EXPECTED LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING. A COLD
FRONT WILL CROSS THE REGION LATE SUNDAY INTO MONDAY BRINGING
SHOWERS...POSSIBLY THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS.
&&
.CLIMATE
COLUMBIA
RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918
RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011
AUGUSTA BUSH
RECORD HIGH TODAY 12/21/13...79 SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898
RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
307 AM CST SAT DEC 21 2013
.DISCUSSION...
744 PM CST
THE FREEZING RAIN ADVISORY FOR NORTH CENTRAL AND EXTREME
NORTHEAST ILLINOIS WAS ALLOWED TO EXPIRE. FREEZING RAIN HAD
DIMINISHED TO FREEZING DRIZZLE EARLY THIS EVENING AND HAS NOW
ENDED ACROSS MOST OF THE ADVISORY AREA. THERE MAY BE A LINGERING
PATCH OR TWO OF FREEZING DRIZZLE BUT THOSE TOO ARE EXPECTED TO
END VERY SHORTLY. RADARS AT MKX...DVN AND ARX HAVE ALL SHOWN A W
TO E CLEARING OF THE WEAK ECHOES WHILE AN AREA OF WEAK ECHOES
ASSOCIATED WITH SOME DRIZZLE AND LIGHT RAIN HAD BLOSSOMED
OVERHEAD BUT IS STEADILY MOVING TO THE E SO THIS PRECIP IS
EXPECTED TO END 9PM CST AS THE TAIL END OF THE LATEST MINOR SHORT
WAVE TROUGH MOVES E OF THE AREA. FORTUNATELY WHERE THIS PRECIP IS
OCCURRING SURFACE TEMPERATURES ARE ABOVE FREEZING.
THE LAKE AND PORTER INDIANA COUNTIES PORTION OF THE DENSE FOG
ADVISORY ALSO WAS ALLOWED TO EXPIRE AS THE FRONTAL BOUNDARY HAD
DRIFTED SLIGHTLY SOUTHWARD ALLOWING WINDS TO BECOME LIGHT
NORTHWEST AND VISIBILITIES TO IMPROVER ABOVE DENSE FOG CRITERIA.
THE REMAINDER OF THE DENSE FOG ADVISORY HAS BEEN EXTENDED UNTIL
9 PM CST. THE WEAK SURFACE REFLECTION OF THE SHORT WAVE WAS IN THE
VPZ-SBN AREA. AS IT CONTINUES SLOWLY TO THE E THE REST OF THE
EVENING THE FRONTAL BOUNDARY WILL CONTINUE TO SAG DEEPER INTO THE
AREA THAT REMAINS UNDER THE ADVISORY WITH AN THINNING OF THE DENSE
FOG EXPECTED TO OCCUR.
TRS
//PREV DISCUSSION...
337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW...
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
DISCUSSION ON WINTER STORM.
WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND
CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES.
THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR
THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A
NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND
MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY
NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS
NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER
AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS.
THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH
TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY
NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS
FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY
SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION
ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL
LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH
SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT
TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR
ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL
LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING
AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE
COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS
OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET
IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER
NORTHWEST TRACK...I CHOOSE TO HOLD OFF.
THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET
ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING
AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN
RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS
MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING
SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF
SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF
I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE
CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY
RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING
THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE
EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE
AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN
AN SPS.
IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY
SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH.
STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY
PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND
WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE
EXPECTED.
THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR
TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW
ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS
THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY
LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS.
TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET
CLOSE TO CHICAGO AND INTERSTATE 80.
MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT
PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL
DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS
IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER
REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA.
KJB
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* LIFR CIGS EXPECTED TO LIFT TO IFR THIS MORNING...WITH SOME
CHANCE FOR MVFR DURING THE DAY.
* IFR VSBY GRADUALLY IMPROVES TO MVFR THROUGH THE MORNING.
* TIMING AND TYPE OF PRECIP ONSET TODAY.
* VARIABLE WEST TO NORTHWEST WINDS TURNING NORTHEAST AND
INCREASING IN SPEED THROUGH THE MORNING.
MDB
//DISCUSSION...UPDATED 09Z...
VSBY HAS BEGUN TO LEVEL OFF AND EVEN SLIGHTLY IMPROVE WITH VALUES
MAINLY IN THE 1-2SM RANGE. EXPECT THAT THERE WILL BE A GRADUAL
IMPROVEMENT THIS MORNING WITH SOME SLIGHT LOW LEVEL DRYING TAKING
PLACE. HOWEVER...IMPROVEMENT WILL PROBABLY BE STUNTED BY
APPROACHING PRECIP INTO THE AFTERNOON. CIGS SHOULD ALSO GRADUALLY
IMPROVE BUT CONFIDENCE IN HOW MUCH REMAINS LOW.
MDB
FROM 06Z...
ONE LOW PRESSURE AREA IS OFF TO THE EAST WHILE THE NEXT LOW
DEVELOPS OVER SOUTHWEST ARKANSAS. DRIZZLE/FREEZING DRIZZLE HAS
DIMINISHED IN COVERAGE DURING THE EVENING BUT VSBY HAS STRUGGLED
TO IMPROVE IN MANY AREAS...THOUGH ORD HAS IMPROVED TO GREATER THAN
6SM. SEVERAL SITES HAVE LOST SOME VSBY IN THE LAST HOUR OR SO
INCLUDING MDW SO WILL CARRY SOME LOWER VSBY THAN PREVIOUS TAFS TO
ACCOUNT FOR THIS. TOUGH TO SAY WHETHER THERE WILL BE MUCH
IMPROVEMENT OVERNIGHT DESPITE THE LACK OF DRIZZLE NOW OCCURRING SO
FURTHER ADJUSTMENTS MAY BE NEEDED. OTHERWISE EXPECT IFR/LIFR CIGS
TO PERSIST THROUGH THE MORNING.
THE ARKANSAS LOW WILL MOVE NORTHEAST TODAY SPREADING PRECIPITATION
NORTHWARD INTO THE AREA. -DZ/-FZDZ MAY DEVELOP AS UPWARD MOTION
BEGINS TO INCREASE MID/LATE MORNING. OTHERWISE CHANCES FOR MIXED
PRECIPITATION WILL INCREASE DURING THE AFTERNOON FROM SOUTH TO
NORTH...WITH RAIN/SNOW/SLEET ALL POSSIBLE. WITH SURFACE TEMPS
RIGHT AROUND FREEZING...SOME FREEZING RAIN MAY ALSO OCCUR. PRECIP
INTENSITY MAXIMIZES BY EARLY EVENING WITH WARMER AIR MOVING IN
ALOFT FAVORING MORE RAIN AT MDW/GYY WITH RAIN/SLEET POSSIBLE AT
ORD/DPA AND A TRANSITION FROM SNOW/SLEET TO SNOW AT RFD WHERE
TEMPS ALOFT WILL BE COLDER. DRIER AIR IS FORECAST TO MOVE IN ALOFT
DURING THE LATE EVENING HOURS WHICH WOULD LIKELY RESULT IN A LULL
IN PRECIP INTENSITY AND FAVOR -DZ/-FZDZ DEPENDING ON SURFACE
TEMPERATURE. RFD MAY REMAIN ON THE FRINGE OF THE DRY SLOT ALLOWING
FOR FLUCTUATIONS BETWEEN SNOW AND -FZDZ. WEST AND NORTHWEST WINDS
WILL TURN NORTHEAST LATER THIS MORNING AND INCREASE IN SPEED INTO
THE EVENING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM CONFIDENCE IN LIFR CIGS LIFTING TO IFR...LOW CONFIDENCE
IN POTENTIAL FOR MVFR CIGS TODAY.
* MEDIUM-HIGH CONFIDENCE IN IFR VSBY IMPROVING TO MVFR THIS
MORNING.
* MEDIUM CONFIDENCE IN PRECIP TIMING/TYPE FORECAST.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...SNOW ESPECIALLY IN THE MORNING. IFR LIKELY. BRIEF LIFR
POSSIBLE EARLY.
MONDAY...CHANCE OF SNOW SHOWERS. MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...CHANCE OF LIGHT SNOW. MVFR/IFR POSSIBLE.
THURSDAY...SLIGHT CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
RATZER
&&
.MARINE...
300 AM CST
ONE AREA OF LOW PRESSURE HAS DEPARTED TO THE EAST AND IS NOW
CROSSING LAKE ERIE. ANOTHER LOW IS DEVELOPING ACROSS WESTERN
ARKANSAS AND WILL LIFT NORTHEAST TODAY. THE LOW WILL THEN REACH
NORTHERN INDIANA SUNDAY MORNING BEFORE BEGINNING TO WEAKEN AS IT
CROSSES NEW ENGLAND SUNDAY EVENING. HIGH PRESSURE WILL MOVE
SOUTHWARD ACROSS MANITOBA AND WESTERN ONTARIO TODAY AND WORK WITH
THE DEVELOPING LOW TO STRENGTHEN THE PRESSURE GRADIENT ACROSS LAKE
MICHIGAN TONIGHT AND SUNDAY MORNING. WINDS WILL TURN NORTHEASTERLY
TODAY ACROSS THE LAKE. SPEEDS LOOK TO TOP OUT AROUND 30 KT...BUT
CANNOT RULE OUT SOME GALE FORCE GUSTS LATE TONIGHT. WILL GO AHEAD
AND HOIST A SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS
FROM THIS EVENING THROUGH SUNDAY AFTERNOON...AND FOR THE INDIANA
NEARSHORE WATERS UNTIL EARLY MONDAY MORNING AS WINDS
TURN FROM NORTHEAST TO NORTH AND THEN NORTHWEST. STRONG HIGH
PRESSURE WILL THEN SPREAD SOUTHWARD INTO THE MIDWEST AND WESTERN
GREAT LAKES MONDAY INTO TUESDAY WITH THE ASSOCIATED RIDGE AXIS
CROSSING LAKE MICHIGAN TUESDAY. DIMINISHING WINDS WILL RESULT...BUT
SPEEDS WILL INCREASE AS THE DIRECTION TURNS SOUTHERLY TUESDAY NIGHT.
LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE CANADIAN PRAIRIES INTO
WESTERN ONTARIO WEDNESDAY WITH THE STRENGTH OF THE LOW DICTATING THE
POTENTIAL FOR GALES WEDNESDAY. THE LOW WILL PASS LATER WEDNESDAY
TURNING WINDS WESTERLY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...4 PM SATURDAY TO 10 AM SUNDAY.
FREEZING RAIN ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 1 PM
SATURDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 10 PM SATURDAY.
WINTER WEATHER ADVISORY...ILZ006-ILZ012...4 PM SATURDAY TO 10 AM
SUNDAY.
WINTER WEATHER ADVISORY...ILZ019-ILZ020-ILZ021-ILZ022...NOON
SATURDAY TO 10 PM SATURDAY.
WINTER WEATHER ADVISORY...ILZ013-ILZ014...2 PM SATURDAY TO 10 PM
SATURDAY.
IN...FREEZING RAIN ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 1 PM
SATURDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 10 PM
SATURDAY.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1210 AM CST SAT DEC 21 2013
.DISCUSSION...
744 PM CST
THE FREEZING RAIN ADVISORY FOR NORTH CENTRAL AND EXTREME
NORTHEAST ILLINOIS WAS ALLOWED TO EXPIRE. FREEZING RAIN HAD
DIMINISHED TO FREEZING DRIZZLE EARLY THIS EVENING AND HAS NOW
ENDED ACROSS MOST OF THE ADVISORY AREA. THERE MAY BE A LINGERING
PATCH OR TWO OF FREEZING DRIZZLE BUT THOSE TOO ARE EXPECTED TO
END VERY SHORTLY. RADARS AT MKX...DVN AND ARX HAVE ALL SHOWN A W
TO E CLEARING OF THE WEAK ECHOES WHILE AN AREA OF WEAK ECHOES
ASSOCIATED WITH SOME DRIZZLE AND LIGHT RAIN HAD BLOSSOMED
OVERHEAD BUT IS STEADILY MOVING TO THE E SO THIS PRECIP IS
EXPECTED TO END 9PM CST AS THE TAIL END OF THE LATEST MINOR SHORT
WAVE TROUGH MOVES E OF THE AREA. FORTUNATELY WHERE THIS PRECIP IS
OCCURRING SURFACE TEMPERATURES ARE ABOVE FREEZING.
THE LAKE AND PORTER INDIANA COUNTIES PORTION OF THE DENSE FOG
ADVISORY ALSO WAS ALLOWED TO EXPIRE AS THE FRONTAL BOUNDARY HAD
DRIFTED SLIGHTLY SOUTHWARD ALLOWING WINDS TO BECOME LIGHT
NORTHWEST AND VISIBILITIES TO IMPROVER ABOVE DENSE FOG CRITERIA.
THE REMAINDER OF THE DENSE FOG ADVISORY HAS BEEN EXTENDED UNTIL
9 PM CST. THE WEAK SURFACE REFLECTION OF THE SHORT WAVE WAS IN THE
VPZ-SBN AREA. AS IT CONTINUES SLOWLY TO THE E THE REST OF THE
EVENING THE FRONTAL BOUNDARY WILL CONTINUE TO SAG DEEPER INTO THE
AREA THAT REMAINS UNDER THE ADVISORY WITH AN THINNING OF THE DENSE
FOG EXPECTED TO OCCUR.
TRS
//PREV DISCUSSION...
337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW...
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
DISCUSSION ON WINTER STORM.
WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND
CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES.
THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR
THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A
NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND
MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY
NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS
NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER
AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS.
THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH
TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY
NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS
FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY
SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION
ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL
LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH
SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT
TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR
ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL
LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING
AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE
COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS
OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET
IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER
NORTHWEST TRACK...I CHOOSE TO HOLD OFF.
THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET
ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING
AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN
RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS
MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING
SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF
SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF
I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE
CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY
RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING
THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE
EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE
AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN
AN SPS.
IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY
SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH.
STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY
PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND
WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE
EXPECTED.
THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR
TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW
ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS
THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY
LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS.
TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET
CLOSE TO CHICAGO AND INTERSTATE 80.
MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT
PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL
DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS
IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER
REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA.
KJB
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* IFR/LIFR CIGS CONTINUING OVERNIGHT AND LIKELY THROUGH
SATURDAY...THOUGH A BRIEF PERIOD OF MVFR IS POSSIBLE IN THE
MORNING.
* IFR VSBY AT MDW MAY IMPROVE SLIGHTLY LATER TONIGHT.
* TIMING AND TYPE OF PRECIP ONSET LATER TODAY.
MDB
//DISCUSSION...UPDATED 06Z...
ONE LOW PRESSURE AREA IS OFF TO THE EAST WHILE THE NEXT LOW
DEVELOPS OVER SOUTHWEST ARKANSAS. DRIZZLE/FREEZING DRIZZLE HAS
DIMINISHED IN COVERAGE DURING THE EVENING BUT VSBY HAS STRUGGLED
TO IMPROVE IN MANY AREAS...THOUGH ORD HAS IMPROVED TO GREATER THAN
6SM. SEVERAL SITES HAVE LOST SOME VSBY IN THE LAST HOUR OR SO
INCLUDING MDW SO WILL CARRY SOME LOWER VSBY THAN PREVIOUS TAFS TO
ACCOUNT FOR THIS. TOUGH TO SAY WHETHER THERE WILL BE MUCH
IMPROVEMENT OVERNIGHT DESPITE THE LACK OF DRIZZLE NOW OCCURRING SO
FURTHER ADJUSTMENTS MAY BE NEEDED. OTHERWISE EXPECT IFR/LIFR CIGS
TO PERSIST THROUGH THE MORNING.
THE ARKANSAS LOW WILL MOVE NORTHEAST TODAY SPREADING PRECIPITATION
NORTHWARD INTO THE AREA. -DZ/-FZDZ MAY DEVELOP AS UPWARD MOTION
BEGINS TO INCREASE MID/LATE MORNING. OTHERWISE CHANCES FOR MIXED
PRECIPITATION WILL INCREASE DURING THE AFTERNOON FROM SOUTH TO
NORTH...WITH RAIN/SNOW/SLEET ALL POSSIBLE. WITH SURFACE TEMPS
RIGHT AROUND FREEZING...SOME FREEZING RAIN MAY ALSO OCCUR. PRECIP
INTENSITY MAXIMIZES BY EARLY EVENING WITH WARMER AIR MOVING IN
ALOFT FAVORING MORE RAIN AT MDW/GYY WITH RAIN/SLEET POSSIBLE AT
ORD/DPA AND A TRANSITION FROM SNOW/SLEET TO SNOW AT RFD WHERE
TEMPS ALOFT WILL BE COLDER. DRIER AIR IS FORECAST TO MOVE IN ALOFT
DURING THE LATE EVENING HOURS WHICH WOULD LIKELY RESULT IN A LULL
IN PRECIP INTENSITY AND FAVOR -DZ/-FZDZ DEPENDING ON SURFACE
TEMPERATURE. RFD MAY REMAIN ON THE FRINGE OF THE DRY SLOT ALLOWING
FOR FLUCTUATIONS BETWEEN SNOW AND -FZDZ. WEST AND NORTHWEST WINDS
WILL TURN NORTHEAST LATER THIS MORNING AND INCREASE IN SPEED INTO
THE EVENING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN IFR/LIFR CIGS CONTINUING OVERNIGHT. LOW
CONFIDENCE IN ANY IMPROVEMENT TO MVFR CIGS.
* LOW-MEDIUM CONFIDENCE IN SOME VSBY IMPROVEMENT AT MDW
OVERNIGHT.
* MEDIUM CONFIDENCE IN TIMING/PRECIP TYPE TRENDS LATER TODAY.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...SNOW ESPECIALLY IN THE MORNING. IFR LIKELY. BRIEF LIFR
POSSIBLE EARLY.
MONDAY...CHANCE OF SNOW SHOWERS. MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...CHANCE OF LIGHT SNOW. MVFR/IFR POSSIBLE.
THURSDAY...SLIGHT CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
RATZER
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...6 PM SATURDAY TO 6 PM SUNDAY.
WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM
SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
355 AM CST Sat Dec 21 2013
...Updated for short term discussion...
.SHORT TERM...(This evening through Saturday)
ISSUED AT 355 AM CST SAT DEC 21 2013
A strong shortwave trough centered west of El Paso early this
morning will eject northeastward across the southern plains through
this evening. Plenty of low level moisture was being ejected into
this system from the south. The deformation/trowal will set up
across southwestern Kansas later today and the 06z NAM and 00 UTC
ECMWF seem to have the best handle on the distribution and amounts
of snow. Given that this is a fast moving system, snow totals of 2
to 5 inches are generally expected in the advisory area along and
southeast of a line from Elkhart to Garden City to Ness City to
LaCrosse, with the highest amounts from Meade eastward into Barber
and Pratt counties. A few locations could reach 6 inches. The snow
may start off as sleet or freezing rain in south central Kansas
later this morning since RAP soundings show an elevated warm layer
around 1C through 18Z. Temperatures may rise into the upper 20s and
lower 30s before the snow arrives, and then fall back into the mid
20s. Afternoon temperatures will be warmer in places like Syracuse,
Scott City and Dighton where not much in the way of snow is
expected. Temperatures tonight will be held up by 10kt north winds
and cloud cover; but with fairly chilly air pushing southward out of
the northern plains in the wake of the storm system, temperatures
should drop into the teens.
.LONG TERM...(Sunday through Friday)
ISSUED AT 246 AM CST SAT DEC 21 2013
Models this morning were in fairly good agreement with lifting a
weakening upper level trough across the Mid Mississippi Valley on
Sunday. At the same time a northern branch upper level trough will
move out of the Rockies and across the Central Plains as an area
of high pressure at the surface builds into western Kansas.
Although no measurable precipitation is expected with this next
system, there will be some increasing clouds late Sunday into
Sunday night. This increasing cloud cover will limit how cold
temperatures will fall Sunday night, however give light winds and
fresh snow cover across western Kansas will still undercut the
coolest guidance for overnight lows. Temperatures falling back
into the single digits still looks reasonable. Lows near zero no
out of the question near the Oklahoma border if skies remain clear
for several hours after midnight.
Westerly downslope flow will improve early next week which will
allow temperatures to gradually warm. Snow cover will limit how
much warming will occur Monday and Tuesday, but at this time the
latest CRExtendFcst_Init still looks reasonable. Where the heavier
snowfall is expected later today the afternoon temperatures are
expected to warm into the upper 30s by Tuesday afternoon.
Elsewhere highs in the mid to upper 40s still appear likely given
the 850mb temperature trends from the GFS and ECMWF. This slow
warming trend will briefly end mid week as a cold front drops
south across Kansas Tuesday night Wednesday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1202 AM CST SAT DEC 21 2013
A strong upper level system will pass across Oklahoma on Saturday.
CIGS will lower to IFR at KDDC as snow develops by 18-21z, with
visibilities as low as 1 mile in the heaviest snow between 21-24z.
KHYS and KGCK will be on the edge of the precipitation shield so
that only minor restrictions to visibility to 1-3 miles are
expected. The snow will be ending after 02z and ceilings and
visibilities will dramatically improve.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 30 17 28 4 / 90 90 0 0
GCK 31 18 29 9 / 50 30 0 0
EHA 28 20 32 17 / 90 20 0 0
LBL 28 18 29 11 / 100 40 0 0
HYS 32 16 28 10 / 40 60 10 20
P28 29 17 27 3 / 100 90 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Midnight CST tonight FOR KSZ045-
046-063>066-075>081-084>090.
&&
$$
SHORT TERM...Finch
LONG TERM...Burgert
AVIATION...Finch
AREA FORECAST DISCUSSION
NWS JACKSON KY
306 AM EST SAT DEC 21 2013
.UPDATE...
ISSUED AT 119 AM EST SAT DEC 21 2013
BASED ON RECENT TRENDS...UPDATED TO LOWER WINDS SLIGHTLY OVERNIGHT AND TO
RAISE MIN TEMPS A BIT.
UPDATE ISSUED AT 1100 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA AS OF 04Z FEATURE SOME SCATTERED
SHOWERS MOVING NORTHEAST FROM TN INTO THE SOUTH CENTRAL AND SOUTHERN
I-75 CORRIDOR OF KENTUCKY. GENERALLY...THE NAM AND HRRR ARE AGREEING
ON ISOLATED TO SCATTERED SHOWERS SKIRTING THE WESTERN EXTEND OF THE
CWA...OR I-75 CORRIDOR THROUGH THE REST OF THE NIGHT. THE BEST LIFT
AND MOISTURE ARRIVES IN THE NORTHWEST IN THE 09Z TO 12Z TIME FRAME AND
IF THERE EVER IS A CHANCE FOR THUNDER TONIGHT...IT WILL OCCUR DURING
THIS PERIOD IN THE PREDAWN HOURS AND KEPT A SLIGHT CHANCE IN THE
FORECAST DUE TO THE LACK OF LIFT AND MOISTURE AT THIS TIME. HAVE
UPDATED AND SENT OUT A FRESH ZFP TO ACCOUNT FOR THIS ADJUSTMENT AND
LOADED CURRENT OBSERVATIONS AND SENT GRIDS TO NDFD.
UPDATE ISSUED AT 830 PM EST FRI DEC 20 2013
AS OF 0130Z SOME SHOWERS ARE BEGINNING TO DEVELOP AND MOVE INTO THE
AREA FROM THE SOUTH AS THE MOISTURE SURGE AND LIFT DEVELOPS AND MOVES
IN FROM THE SOUTHWEST. UPDATED THE GRIDS WITH THE MOST CURRENT OBS
AND HAVE SENT THEM TO NDFD. THE REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 715 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA FEATURE A FEW STRAY SHOWERS
PASSING THROUGH EASTERN KENTUCKY BUT OTHERWISE ANY MEASURABLE PRECIP
LOOKS TO BE NONEXISTENT FOR AT LEAST THE NEXT COUPLE OF HOURS SO AT
THIS POINT...SLIGHT CHANCE SHOWERS LOOK TO BE THE WAY TO GO AND THEN
AS LIFT AND MOISTURE SURGE INCREASES TONIGHT...WILL INTRODUCE SOME
CHANCE AND LIKELY SHOWERS WITH AT LEAST SOME NOTICEABLE ISENTROPIC
LIFT JUST SKIRTING TO THE WEST OF THE I-75 CORRIDOR...WILL LEAVE
SLIGHT CHANCE THUNDERSTORMS JUST IN THE WESTERN ZONES AND ONLY
STARTING IN THE PREDAWN HOURS. HAVE ADJUSTED FOR PRECIP CHANCES
ARRIVING LATER SO A FRESH ZFP HAS BEEN ISSUED FOR THESE SLIGHT
CHANGES. OTHERWISE...HAVE LOADED IN THE LATEST OB AND SENT THE GRIDS
TO NDFD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 359 PM EST FRI DEC 20 2013
ISOLATED TO SCATTERED SHOWERS HAVE BEEN MOVING ACROSS EASTERN
KENTUCKY TODAY. A FRONTAL SYSTEM EXTENDS FROM SOUTHERN MICHIGAN TO
NORTH CENTRAL TEXAS AND HAS MULTIPLE WAVES MOVING ALONG IT. THIS
WILL RESULT IN THE FRONT BOWING TO THE NORTH AHEAD OF THE LOW AND
THEN BOWING DOWN ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE THE
FRONTS TO MOVE PRECIPITATION IN AND OUT OF THE AREA. THE COLD FRONT
WILL FINALLY MOVE THROUGH THE AREA ON SUNDAY WHEN THE UPPER TROUGH
MOVES TO THE WEST AND NORTH OF THE AREA. THE LATEST MODEL RUNS ARE
MOVING THE FRONT THROUGH THE AREA ON SUNDAY MORNING. THERE WILL BE A
STRONG LOW LEVEL JET OUT AHEAD OF THE FRONT. THE JET WILL BE MOVING
INTO THE AREA ON SATURDAY NIGHT. PUT OUT A LAKE WIND ADVISORY TO
COVER THE WIND GUSTS EXPECTED WITH THIS SYSTEM. IT IS POSSIBLE THAT
THIS MAY HAVE TO BE UPGRADED TO A WIND ADVISORY...HOWEVER SINCE IT
WILL BE NIGHT TIME...IT WILL BE HARDER TO MIX THE STRONGER GUSTS DOWN
TO THE SURFACE. THE UPPER ELEVATIONS WOULD BE MOST LIKELY TO SEE THE
STRONGEST GUSTS. THE SEVERE WEATHER THREAT IS ALSO MINIMIZED DUE TO
THE TIME OF DAY THE FRONT WILL BE MOVING THROUGH THE AREA. THE AMOUNT
OF PRECIPITATION EXPECTED WITH THIS SYSTEM IS LIMITED...BECAUSE THE
FRONT WILL BE MOVING FAIRLY QUICKLY THROUGH THE AREA. THE BEST CHANCE
TO SEE THE HEAVY RAIN WILL BE OUT AHEAD OF THE FRONT ON SATURDAY
NIGHT. NEAR RECORD TEMPERATURES ARE EXPECTED TOMORROW.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 306 AM EST SAT DEC 21 2013
THE SURFACE COLD FRONT WHICH BROUGHT THE RAIN AND WINDS DURING THE
SHORT TERM WILL HAVE MOVED SE OF THE REGION BY 0Z MONDAY.
HOWEVER...MODELS STILL SHOW A POOL OF MOISTURE/LIGHT PRECIP
REMAINING OVER THE FAR SE COUNTIES OF THE CWA. BASED ON LATEST
SOUNDINGS...THERE DOES SEEM TO BE A THIN LAYER OF DRY AIR NEAR THE
SURFACE WHICH COULD INHIBIT RAIN ACROSS THE REMAINDER OF THE REGION.
AS A RESULT...WAS RELUCTANT TO PUT IN ANYTHING OTHER THAN SLIGHT
CHANCE POPS FOR SEVERAL HOURS IN THESE LOCATIONS...BUT IF PRECIP
DOES OCCUR...IT WILL BE VERY LIGHT WITH LITTLE TO NO ACCUMULATION
EXPECTED. IN CONTRAST...SE KY COULD SEE SEVERAL HUNDREDTHS OF AN
INCH. THIS IS STILL RATHER UNIMPACTFUL. AN ABUNDANT AMOUNT OF DRY
AIR SEEMS TO BE PULLING IN ALOFT TOO...SO EXPECT ANY CLOUD COVER TO
BE CONFINED TO THE LOW LEVELS /LOW LEVEL CU/ INTO THE AFTERNOON HOURS
ACROSS THE REGION. THOUGH WINDS ALOFT WILL CONTINUE TO BE QUITE
STRONG...WITH HIGH PRESSURE COMING INTO PLAY...AND SIGNIFICANT DRYING
ALOFT...A DECENT NIGHT TIME INVERSION WILL FORM SUNDAY
NIGHT...PREVENTING THESE HIGHER WINDS FROM REACHING THE SURFACE. BY
MONDAY AFTERNOON...THE INVERSION WILL LIFT...AND WINDS WILL BE ABLE
TO MIX DOWN...BUT STILL SHOULD ONLY BE AROUND 15KTS OR LESS.
FOR MONDAY NIGHT...THE UPPER LEVEL TROUGH AXIS WILL PASS ACROSS
EASTERN KY. ONCE KY FINDS ITSELF ON THE BACK EDGE OF THIS
TROUGH...EXPECT AN ABUNDANT AMOUNT OF DRY AND COLD CANADIAN AIR TO
RUSH INTO THE REGION. FORECAST SOUNDINGS WILL COOL AND DRY
DRAMATICALLY. DAYTIME HIGHS TUESDAY WILL BE SIGNIFICANTLY
LOWER..BARELY REACHING FREEZING IN MOST LOCATIONS. TUESDAY NIGHT
WILL BE A SIMILAR STORY...WITH LOWS EXPECTED TO DROP DOWN INTO THE
UPPER TEENS TO NEAR 20.
MODELS ARE STILL SEEING A HIGH AMOUNT OF DISAGREEMENT IN THE LONG
TERM...BUT DO EXPECT SURFACE HIGH PRESSURE AND UPPER LEVEL RIDGING
TO LAST THROUGH WEDNESDAY NIGHT. THEN THERE IS A POTENTIAL FOR
ANOTHER SHORTWAVE TO MOVE INTO/NEAR THE OHIO VALLEY REGION DURING
THE DAY THURSDAY. WITH SUCH AN ABUNDANT AMOUNT OF DRY AIR IN
PLACE...DO NOT EXPECT ANY IMPACTS ON THURSDAY OTHER THAN HIGH
CLOUDS. HOWEVER...WINDS WILL HAVE SWITCHED TO A MORE SRLY
DIRECTION...ALLOWING FOR SOMEWHAT WARMER TEMPERATURES. A SHALLOW
LAYER OF MOISTURE SHOULD MAKE IT DOWN TO THE SURFACE BY FRIDAY
AFTERNOON/EVENING. BUT WILL AGREE WITH PREVIOUS FORECAST...THE
MOISTURE IS SO SHALLOW...WOULD NOT EXPECT MUCH MORE THAN A LIGHT
RAIN/DRIZZLE OR LIGHT SNOW EVENT. LITTLE TO NO ACCUMULATIONS ARE
EXPECTED AT THIS TIME. WITH CLOUD COVER IN PLACE...TEMPERATURES
SHOULD MODULATE AFTER THURSDAY...WITH HIGHS AND LOWS EXPECTED TO BE
CLOSER TO NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 106 AM EST SAT DEC 21 2013
CONDITIONS AT TAF ISSUANCE WERE A MIX OF MVFR AND LOW END VFR DUE TO
CEILINGS. THE MVFR WAS MOST PREVALENT IN THE WEST AND THE VFR MOST
PREVALENT IN THE EAST. THIS GENERAL SCENARIO IS EXPECTED TO PERSIST
OVERNIGHT...FOLLOWED BY PERHAPS A BIT OF IMPROVEMENT ON SATURDAY
MORNING. WITH MORE HUMID LOW LEVEL AIR BEING ADVECTED INTO THE REGION
FROM THE SW AND SOME LIMITED HEATING...WILL LOOK FOR A BKN LAYER OF
MVFR LEVEL STRATOCUMULUS TO DEVELOP OVER MUCH OF THE AREA ON SATURDAY
AFTERNOON...AND THEN DISSIPATE SATURDAY EVENING. SOME SHOWERS WILL
ALSO BE POSSIBLE ON SATURDAY...WITH THE GREATEST PROBABILITY IN THE
NW AROUND KIOB...AND THE LOWEST PROBABILITY IN THE SE NEAR THE VA
BORDER.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST SUNDAY FOR
KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...HAL
SHORT TERM...JJ
LONG TERM...JMW
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
119 AM EST SAT DEC 21 2013
.UPDATE...
ISSUED AT 119 AM EST SAT DEC 21 2013
BASED ON RECENT TRENDS...UPDATED TO LOWER WINDS SLIGHTLY OVERNIGHT AND TO
RAISE MIN TEMPS A BIT.
UPDATE ISSUED AT 1100 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA AS OF 04Z FEATURE SOME SCATTERED
SHOWERS MOVING NORTHEAST FROM TN INTO THE SOUTH CENTRAL AND SOUTHERN
I-75 CORRIDOR OF KENTUCKY. GENERALLY...THE NAM AND HRRR ARE AGREEING
ON ISOLATED TO SCATTERED SHOWERS SKIRTING THE WESTERN EXTEND OF THE
CWA...OR I-75 CORRIDOR THROUGH THE REST OF THE NIGHT. THE BEST LIFT
AND MOISTURE ARRIVES IN THE NORTHWEST IN THE 09Z TO 12Z TIME FRAME AND
IF THERE EVER IS A CHANCE FOR THUNDER TONIGHT...IT WILL OCCUR DURING
THIS PERIOD IN THE PREDAWN HOURS AND KEPT A SLIGHT CHANCE IN THE
FORECAST DUE TO THE LACK OF LIFT AND MOISTURE AT THIS TIME. HAVE
UPDATED AND SENT OUT A FRESH ZFP TO ACCOUNT FOR THIS ADJUSTMENT AND
LOADED CURRENT OBSERVATIONS AND SENT GRIDS TO NDFD.
UPDATE ISSUED AT 830 PM EST FRI DEC 20 2013
AS OF 0130Z SOME SHOWERS ARE BEGINNING TO DEVELOP AND MOVE INTO THE
AREA FROM THE SOUTH AS THE MOISTURE SURGE AND LIFT DEVELOPS AND MOVES
IN FROM THE SOUTHWEST. UPDATED THE GRIDS WITH THE MOST CURRENT OBS
AND HAVE SENT THEM TO NDFD. THE REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 715 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA FEATURE A FEW STRAY SHOWERS
PASSING THROUGH EASTERN KENTUCKY BUT OTHERWISE ANY MEASURABLE PRECIP
LOOKS TO BE NONEXISTENT FOR AT LEAST THE NEXT COUPLE OF HOURS SO AT
THIS POINT...SLIGHT CHANCE SHOWERS LOOK TO BE THE WAY TO GO AND THEN
AS LIFT AND MOISTURE SURGE INCREASES TONIGHT...WILL INTRODUCE SOME
CHANCE AND LIKELY SHOWERS WITH AT LEAST SOME NOTICEABLE ISENTROPIC
LIFT JUST SKIRTING TO THE WEST OF THE I-75 CORRIDOR...WILL LEAVE
SLIGHT CHANCE THUNDERSTORMS JUST IN THE WESTERN ZONES AND ONLY
STARTING IN THE PREDAWN HOURS. HAVE ADJUSTED FOR PRECIP CHANCES
ARRIVING LATER SO A FRESH ZFP HAS BEEN ISSUED FOR THESE SLIGHT
CHANGES. OTHERWISE...HAVE LOADED IN THE LATEST OB AND SENT THE GRIDS
TO NDFD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 359 PM EST FRI DEC 20 2013
ISOLATED TO SCATTERED SHOWERS HAVE BEEN MOVING ACROSS EASTERN
KENTUCKY TODAY. A FRONTAL SYSTEM EXTENDS FROM SOUTHERN MICHIGAN TO
NORTH CENTRAL TEXAS AND HAS MULTIPLE WAVES MOVING ALONG IT. THIS
WILL RESULT IN THE FRONT BOWING TO THE NORTH AHEAD OF THE LOW AND
THEN BOWING DOWN ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE THE
FRONTS TO MOVE PRECIPITATION IN AND OUT OF THE AREA. THE COLD FRONT
WILL FINALLY MOVE THROUGH THE AREA ON SUNDAY WHEN THE UPPER TROUGH
MOVES TO THE WEST AND NORTH OF THE AREA. THE LATEST MODEL RUNS ARE
MOVING THE FRONT THROUGH THE AREA ON SUNDAY MORNING. THERE WILL BE A
STRONG LOW LEVEL JET OUT AHEAD OF THE FRONT. THE JET WILL BE MOVING
INTO THE AREA ON SATURDAY NIGHT. PUT OUT A LAKE WIND ADVISORY TO
COVER THE WIND GUSTS EXPECTED WITH THIS SYSTEM. IT IS POSSIBLE THAT
THIS MAY HAVE TO BE UPGRADED TO A WIND ADVISORY...HOWEVER SINCE IT
WILL BE NIGHT TIME...IT WILL BE HARDER TO MIX THE STRONGER GUSTS DOWN
TO THE SURFACE. THE UPPER ELEVATIONS WOULD BE MOST LIKELY TO SEE THE
STRONGEST GUSTS. THE SEVERE WEATHER THREAT IS ALSO MINIMIZED DUE TO
THE TIME OF DAY THE FRONT WILL BE MOVING THROUGH THE AREA. THE AMOUNT
OF PRECIPITATION EXPECTED WITH THIS SYSTEM IS LIMITED...BECAUSE THE
FRONT WILL BE MOVING FAIRLY QUICKLY THROUGH THE AREA. THE BEST CHANCE
TO SEE THE HEAVY RAIN WILL BE OUT AHEAD OF THE FRONT ON SATURDAY
NIGHT. NEAR RECORD TEMPERATURES ARE EXPECTED TOMORROW.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 409 PM EST FRI DEC 20 2013
THE EXTENDED WILL START OUT WITH A DEEP TROUGH ACROSS THE CENTRAL
CONUS. THIS TROUGH WILL DAMPEN AS IT BECOMES MORE CONSOLIDATED OVER
NEW ENGLAND BY TUESDAY. A SURFACE COLD FRONT WILL CONTINUE ITS SAG
TO THE SOUTHEAST SUNDAY NIGHT...WITH DEEPER MOISTURE EXITING EASTERN
KENTUCKY BY MONDAY MORNING. COLDER AIR WILL BE MOVING IN...WITH
TEMPERATURES LIKELY FALLING THROUGH THE DAY ON MONDAY. THERE
CONTINUES TO BE ENOUGH MOISTURE ADVERTISED FROM MONDAY THROUGH
MONDAY NIGHT TO JUSTIFY SOME SLIGHT CHANCE POPS...LIKELY IN THE FORM
OF FINE RAIN/DRIZZLE OR A BIT OF LIGHT SNOW OR FLURRIES.
DRY AND COLDER WEATHER WILL BE IN PLACE HEADING INTO MID-WEEK...WITH
LOWS DOWN INTO THE TEENS AND 20S TUESDAY AND WEDNESDAY MORNINGS.
ANOTHER TROUGH WILL TAKE AIM AT THE REGION BY THURSDAY...HOWEVER
THE MODEL DISAGREEMENT REMAINS. IN GENERAL...THERE HAS BEEN A DRIER
TREND...SO UNDERCUT THE GIVEN BLENDED MODEL GUIDANCE OUTPUT A BIT
AND KEPT SLIGHT CHANCE POPS IN. TEMPERATURE PROFILES SUPPORT
RAIN/SNOW...HOWEVER LITTLE IF ANY SNOW ACCUMULATION LOOKS TO OCCUR.
ANOTHER REINFORCING SHOT OF DRY AND COLDER HIGH PRESSURE WILL FOLLOW
FOR FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 106 AM EST SAT DEC 21 2013
CONDITIONS AT TAF ISSUANCE WERE A MIX OF MVFR AND LOW END VFR DUE TO
CEILINGS. THE MVFR WAS MOST PREVALENT IN THE WEST AND THE VFR MOST
PREVALENT IN THE EAST. THIS GENERAL SCENARIO IS EXPECTED TO PERSIST
OVERNIGHT...FOLLOWED BY PERHAPS A BIT OF IMPROVEMENT ON SATURDAY
MORNING. WITH MORE HUMID LOW LEVEL AIR BEING ADVECTED INTO THE REGION
FROM THE SW AND SOME LIMITED HEATING...WILL LOOK FOR A BKN LAYER OF
MVFR LEVEL STRATOCUMULUS TO DEVELOP OVER MUCH OF THE AREA ON SATURDAY
AFTERNOON...AND THEN DISSIPATE SATURDAY EVENING. SOME SHOWERS WILL
ALSO BE POSSIBLE ON SATURDAY...WITH THE GREATEST PROBABILITY IN THE
NW AROUND KIOB...AND THE LOWEST PROBABILITY IN THE SE NEAR THE VA
BORDER.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST SUNDAY FOR
KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...HAL
SHORT TERM...JJ
LONG TERM...GEOGERIAN
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
106 AM EST SAT DEC 21 2013
.UPDATE...
ISSUED AT 1100 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA AS OF 04Z FEATURE SOME SCATTERED
SHOWERS MOVING NORTHEAST FROM TN INTO THE SOUTH CENTRAL AND SOUTHERN
I-75 CORRIDOR OF KENTUCKY. GENERALLY...THE NAM AND HRRR ARE AGREEING
ON ISOLATED TO SCATTERED SHOWERS SKIRTING THE WESTERN EXTEND OF THE
CWA...OR I-75 CORRIDOR THROUGH THE REST OF THE NIGHT. THE BEST LIFT
AND MOISTURE ARRIVES IN THE NORTHWEST IN THE 09Z TO 12Z TIME FRAME AND
IF THERE EVER IS A CHANCE FOR THUNDER TONIGHT...IT WILL OCCUR DURING
THIS PERIOD IN THE PREDAWN HOURS AND KEPT A SLIGHT CHANCE IN THE
FORECAST DUE TO THE LACK OF LIFT AND MOISTURE AT THIS TIME. HAVE
UPDATED AND SENT OUT A FRESH ZFP TO ACCOUNT FOR THIS ADJUSTMENT AND
LOADED CURRENT OBSERVATIONS AND SENT GRIDS TO NDFD.
UPDATE ISSUED AT 830 PM EST FRI DEC 20 2013
AS OF 0130Z SOME SHOWERS ARE BEGINNING TO DEVELOP AND MOVE INTO THE
AREA FROM THE SOUTH AS THE MOISTURE SURGE AND LIFT DEVELOPS AND MOVES
IN FROM THE SOUTHWEST. UPDATED THE GRIDS WITH THE MOST CURRENT OBS
AND HAVE SENT THEM TO NDFD. THE REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 715 PM EST FRI DEC 20 2013
CURRENT CONDITIONS ACROSS THE AREA FEATURE A FEW STRAY SHOWERS
PASSING THROUGH EASTERN KENTUCKY BUT OTHERWISE ANY MEASURABLE PRECIP
LOOKS TO BE NONEXISTENT FOR AT LEAST THE NEXT COUPLE OF HOURS SO AT
THIS POINT...SLIGHT CHANCE SHOWERS LOOK TO BE THE WAY TO GO AND THEN
AS LIFT AND MOISTURE SURGE INCREASES TONIGHT...WILL INTRODUCE SOME
CHANCE AND LIKELY SHOWERS WITH AT LEAST SOME NOTICEABLE ISENTROPIC
LIFT JUST SKIRTING TO THE WEST OF THE I-75 CORRIDOR...WILL LEAVE
SLIGHT CHANCE THUNDERSTORMS JUST IN THE WESTERN ZONES AND ONLY
STARTING IN THE PREDAWN HOURS. HAVE ADJUSTED FOR PRECIP CHANCES
ARRIVING LATER SO A FRESH ZFP HAS BEEN ISSUED FOR THESE SLIGHT
CHANGES. OTHERWISE...HAVE LOADED IN THE LATEST OB AND SENT THE GRIDS
TO NDFD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 359 PM EST FRI DEC 20 2013
ISOLATED TO SCATTERED SHOWERS HAVE BEEN MOVING ACROSS EASTERN
KENTUCKY TODAY. A FRONTAL SYSTEM EXTENDS FROM SOUTHERN MICHIGAN TO
NORTH CENTRAL TEXAS AND HAS MULTIPLE WAVES MOVING ALONG IT. THIS
WILL RESULT IN THE FRONT BOWING TO THE NORTH AHEAD OF THE LOW AND
THEN BOWING DOWN ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE THE
FRONTS TO MOVE PRECIPITATION IN AND OUT OF THE AREA. THE COLD FRONT
WILL FINALLY MOVE THROUGH THE AREA ON SUNDAY WHEN THE UPPER TROUGH
MOVES TO THE WEST AND NORTH OF THE AREA. THE LATEST MODEL RUNS ARE
MOVING THE FRONT THROUGH THE AREA ON SUNDAY MORNING. THERE WILL BE A
STRONG LOW LEVEL JET OUT AHEAD OF THE FRONT. THE JET WILL BE MOVING
INTO THE AREA ON SATURDAY NIGHT. PUT OUT A LAKE WIND ADVISORY TO
COVER THE WIND GUSTS EXPECTED WITH THIS SYSTEM. IT IS POSSIBLE THAT
THIS MAY HAVE TO BE UPGRADED TO A WIND ADVISORY...HOWEVER SINCE IT
WILL BE NIGHT TIME...IT WILL BE HARDER TO MIX THE STRONGER GUSTS DOWN
TO THE SURFACE. THE UPPER ELEVATIONS WOULD BE MOST LIKELY TO SEE THE
STRONGEST GUSTS. THE SEVERE WEATHER THREAT IS ALSO MINIMIZED DUE TO
THE TIME OF DAY THE FRONT WILL BE MOVING THROUGH THE AREA. THE AMOUNT
OF PRECIPITATION EXPECTED WITH THIS SYSTEM IS LIMITED...BECAUSE THE
FRONT WILL BE MOVING FAIRLY QUICKLY THROUGH THE AREA. THE BEST CHANCE
TO SEE THE HEAVY RAIN WILL BE OUT AHEAD OF THE FRONT ON SATURDAY
NIGHT. NEAR RECORD TEMPERATURES ARE EXPECTED TOMORROW.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 409 PM EST FRI DEC 20 2013
THE EXTENDED WILL START OUT WITH A DEEP TROUGH ACROSS THE CENTRAL
CONUS. THIS TROUGH WILL DAMPEN AS IT BECOMES MORE CONSOLIDATED OVER
NEW ENGLAND BY TUESDAY. A SURFACE COLD FRONT WILL CONTINUE ITS SAG
TO THE SOUTHEAST SUNDAY NIGHT...WITH DEEPER MOISTURE EXITING EASTERN
KENTUCKY BY MONDAY MORNING. COLDER AIR WILL BE MOVING IN...WITH
TEMPERATURES LIKELY FALLING THROUGH THE DAY ON MONDAY. THERE
CONTINUES TO BE ENOUGH MOISTURE ADVERTISED FROM MONDAY THROUGH
MONDAY NIGHT TO JUSTIFY SOME SLIGHT CHANCE POPS...LIKELY IN THE FORM
OF FINE RAIN/DRIZZLE OR A BIT OF LIGHT SNOW OR FLURRIES.
DRY AND COLDER WEATHER WILL BE IN PLACE HEADING INTO MID-WEEK...WITH
LOWS DOWN INTO THE TEENS AND 20S TUESDAY AND WEDNESDAY MORNINGS.
ANOTHER TROUGH WILL TAKE AIM AT THE REGION BY THURSDAY...HOWEVER
THE MODEL DISAGREEMENT REMAINS. IN GENERAL...THERE HAS BEEN A DRIER
TREND...SO UNDERCUT THE GIVEN BLENDED MODEL GUIDANCE OUTPUT A BIT
AND KEPT SLIGHT CHANCE POPS IN. TEMPERATURE PROFILES SUPPORT
RAIN/SNOW...HOWEVER LITTLE IF ANY SNOW ACCUMULATION LOOKS TO OCCUR.
ANOTHER REINFORCING SHOT OF DRY AND COLDER HIGH PRESSURE WILL FOLLOW
FOR FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 106 AM EST SAT DEC 21 2013
CONDITIONS AT TAF ISSUANCE WERE A MIX OF MVFR AND LOW END VFR DUE TO
CEILINGS. THE MVFR WAS MOST PREVALENT IN THE WEST AND THE VFR MOST
PREVALENT IN THE EAST. THIS GENERAL SCENARIO IS EXPECTED TO PERSIST
OVERNIGHT...FOLLOWED BY PERHAPS A BIT OF IMPROVEMENT ON SATURDAY
MORNING. WITH MORE HUMID LOW LEVEL AIR BEING ADVECTED INTO THE REGION
FROM THE SW AND SOME LIMITED HEATING...WILL LOOK FOR A BKN LAYER OF
MVFR LEVEL STRATOCUMULUS TO DEVELOP OVER MUCH OF THE AREA ON SATURDAY
AFTERNOON...AND THEN DISSIPATE SATURDAY EVENING. SOME SHOWERS WILL
ALSO BE POSSIBLE ON SATURDAY...WITH THE GREATEST PROBABILITY IN THE
NW AROUND KIOB...AND THE LOWEST PROBABILITY IN THE SE NEAR THE VA
BORDER.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST SUNDAY FOR
KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...SHALLENBERGER
SHORT TERM...JJ
LONG TERM...GEOGERIAN
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1158 PM CST Fri Dec 20 2013
.UPDATE...
ISSUED AT 1158 PM CST FRI DEC 20 2013
The AVIATION section has been updated for the 06Z TAF issuance.
UPDATE ISSUED AT 1016 PM CST FRI DEC 20 2013
Latest forecast update accounts for colder temperatures following
cold front progressing southeast across the area. As of 04Z, the
front stretched from roughly the Wabash River Valley to just east
of Harrisburg, Illinois to just northwest of Cape Girardeau and
Poplar Bluff, Missouri.
Area Doppler radar mosaic depicts an initial round of showers and
a few thunderstorms over mainly southern Illinois. The next round
of activity was already lifting north across northeast Arkansas
and western Tennessee and will spread across the region overnight.
Utilized a blend of the NAM12, RAP13, and current forecast.
Overall, going forecast appears to remain on track through
Saturday morning. However, two potential scenarios could shift the
forecast in one direction or another.
(1.) The latter part of the RAP13 is much more aggressive
with the southeastward progress of the cold frontal boundary into
western Kentucky by Saturday afternoon. This can easily be
supported by precipitation loading and its cooling effect, which
may effectively push the frontal boundary further south than
currently forecast. If this were to pan out, the potential for
severe weather would essentially focus across the southern
Pennyrile region and further south.
(2.) Meanwhile, the NAM12 is much more insistent that the frontal
boundary will hang up across far southeast Missouri, southeast
Illinois, and even far southern Indiana. If this pans out, then
the severe potential would be much more concerning by Saturday
afternoon and evening.
While the current forecast embraces neither of these extremes,
they are nonetheless worth keeping in mind as we proceed through
what promises to be a heavy rain event at the very least.
&&
.SHORT TERM...(This Evening through Sunday)
ISSUED AT 238 PM CST FRI DEC 20 2013
Flood Watch will continue as is tonight through Saturday night.
Still looking at 2-4+ inches area wide, slightly higher amounts
to 5 inches possible near and just NW of the Ohio River. Front
will enter the area tonight and stall near the Ohio River. Rain
and storms forecast to increase tonight especially after midnight,
continuing through Saturday.
Could see a few strong to severe storms Saturday late day and
evening as wind fields increase substantially with some surface
based instability along and south of the boundary, especially
across west Kentucky. Isolated damaging wind gusts and a brief
short lived tornado or two cannot be ruled out. The activity
should quickly push to the east after midnight Saturday as we
dry slot. Mid level drying will be pronounced, but low level
moisture will linger with SW flow aloft. May be some drizzle into
Sunday but that`s about it, as temperatures fall through the day.
In terms of temps, dew points and winds with the front coming into
the area tonight and Saturday, used a blend of RAP 13km data and
short term 3 hourly GFS/NAM data.
.LONG TERM...(Sunday Night through Friday)
ISSUED AT 238 PM CST FRI DEC 20 2013
In the wake of the weekend storm...colder and drier air will arrive
for early next week. Model soundings depict some lingering moisture
Sunday night until the passage of the 850 mb trough axis. This could
translate into some flurries or drizzle...but no measurable precip
is indicated in the 12z gfs/nam/ecmwf model qpf. By Monday
night...mainly clear skies are expected.
Monday night...the combination of clear skies and decreasing winds
should allow temps to radiate nicely. Will lower Monday night
lows closer to gfs and ecmwf mos...both of which range from 10 to 15
degrees across most of the area.
Tuesday will be another cold day...but there is about a 10 degree
difference between ecmwf and gfs mos highs. The 00z ecmwf is more
progressive with the eastward motion of the thermal trough...while
the 12z gfs lingers the cold air through the day. Will split the
difference between them...which yields highs in the upper 20s to
lower 30s despite sunny skies.
The models depict a 500 mb longwave trough axis setting up over the
Mississippi Valley Christmas Day into Thursday. Shortwaves rotating
through the trough will bring at least some cloudiness...if not
measurable light precip. Model soundings have trended drier during
this time period...and the 12z gfs and gfs ensemble mean show zero
qpf. The 12z ecmwf indicates some patchy light precip. Will follow
the model trends and lower pops into the slight chance category for
Christmas night and Thursday. Precip type would be mainly snow until
boundary layer temps become marginal for snow Thursday
afternoon.
In the wake of the departing longwave trough...another shot of cold
air is expected for Friday. As would be expected seven days
out...there is fair to poor agreement on how cold it will get.
Forecast will represent a blend of gfs/ecmwf temps.
&&
.AVIATION...
ISSUED AT 1158 PM CST FRI DEC 20 2013
Low confidence forecast, with considerable uncertainty in the
frontal position/movement through the period. It does appear that
IFR conditions in heavy rain will prevail at all sites for most,
if not all of the TAF period. Lower conditions will be possible at
times, especially near the front, which unfortunately will be
draped across the terminals for much of the period. The potential
exists for some very strong and gusty south/southwest winds in the
warm sector Saturday afternoon and evening. This would be most
likely at KOWB, but cannot be ruled out at KPAH and KEVV.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH through late Saturday night FOR ILZ075>078-080>094.
MO...FLOOD WATCH through late Saturday night FOR MOZ076-086-087-100-
107>112-114.
IN...FLOOD WATCH through late Saturday night FOR INZ081-082-085>088.
KY...FLOOD WATCH through late Saturday night FOR KYZ001>022.
&&
$$
UPDATE...DRS
AVIATION...DRS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1016 PM CST Fri Dec 20 2013
.UPDATE...
ISSUED AT 1016 PM CST FRI DEC 20 2013
Latest forecast update accounts for colder temperatures following
cold front progressing southeast across the area. As of 04Z, the
front stretched from roughly the Wabash River Valley to just east
of Harrisburg, Illinois to just northwest of Cape Girardeau and
Poplar Bluff, Missouri.
Area Doppler radar mosaic depicts an initial round of showers and
a few thunderstorms over mainly southern Illinois. The next round
of activity was already lifting north across northeast Arkansas
and western Tennessee and will spread across the region overnight.
Utilized a blend of the NAM12, RAP13, and current forecast.
Overall, going forecast appears to remain on track through
Saturday morning. However, two potential scenarios could shift the
forecast in one direction or another.
(1.) The latter part of the RAP13 is much more aggressive
with the southeastward progress of the cold frontal boundary into
western Kentucky by Saturday afternoon. This can easily be
supported by precipitation loading and its cooling effect, which
may effectively push the frontal boundary further south than
currently forecast. If this were to pan out, the potential for
severe weather would essentially focus across the southern
Pennyrile region and further south.
(2.) Meanwhile, the NAM12 is much more insistent that the frontal
boundary will hang up across far southeast Missouri, southeast
Illinois, and even far southern Indiana. If this pans out, then
the severe potential would be much more concerning by Saturday
afternoon and evening.
While the current forecast embraces neither of these extremes,
they are nonetheless worth keeping in mind as we proceed through
what promises to be a heavy rain event at the very least.
&&
.SHORT TERM...(This Evening through Sunday)
ISSUED AT 238 PM CST FRI DEC 20 2013
Flood Watch will continue as is tonight through Saturday night.
Still looking at 2-4+ inches area wide, slightly higher amounts
to 5 inches possible near and just NW of the Ohio River. Front
will enter the area tonight and stall near the Ohio River. Rain
and storms forecast to increase tonight especially after midnight,
continuing through Saturday.
Could see a few strong to severe storms Saturday late day and
evening as wind fields increase substantially with some surface
based instability along and south of the boundary, especially
across west Kentucky. Isolated damaging wind gusts and a brief
short lived tornado or two cannot be ruled out. The activity
should quickly push to the east after midnight Saturday as we
dry slot. Mid level drying will be pronounced, but low level
moisture will linger with SW flow aloft. May be some drizzle into
Sunday but that`s about it, as temperatures fall through the day.
In terms of temps, dew points and winds with the front coming into
the area tonight and Saturday, used a blend of RAP 13km data and
short term 3 hourly GFS/NAM data.
.LONG TERM...(Sunday Night through Friday)
ISSUED AT 238 PM CST FRI DEC 20 2013
In the wake of the weekend storm...colder and drier air will arrive
for early next week. Model soundings depict some lingering moisture
Sunday night until the passage of the 850 mb trough axis. This could
translate into some flurries or drizzle...but no measurable precip
is indicated in the 12z gfs/nam/ecmwf model qpf. By Monday
night...mainly clear skies are expected.
Monday night...the combination of clear skies and decreasing winds
should allow temps to radiate nicely. Will lower Monday night
lows closer to gfs and ecmwf mos...both of which range from 10 to 15
degrees across most of the area.
Tuesday will be another cold day...but there is about a 10 degree
difference between ecmwf and gfs mos highs. The 00z ecmwf is more
progressive with the eastward motion of the thermal trough...while
the 12z gfs lingers the cold air through the day. Will split the
difference between them...which yields highs in the upper 20s to
lower 30s despite sunny skies.
The models depict a 500 mb longwave trough axis setting up over the
Mississippi Valley Christmas Day into Thursday. Shortwaves rotating
through the trough will bring at least some cloudiness...if not
measurable light precip. Model soundings have trended drier during
this time period...and the 12z gfs and gfs ensemble mean show zero
qpf. The 12z ecmwf indicates some patchy light precip. Will follow
the model trends and lower pops into the slight chance category for
Christmas night and Thursday. Precip type would be mainly snow until
boundary layer temps become marginal for snow Thursday
afternoon.
In the wake of the departing longwave trough...another shot of cold
air is expected for Friday. As would be expected seven days
out...there is fair to poor agreement on how cold it will get.
Forecast will represent a blend of gfs/ecmwf temps.
&&
.AVIATION...
ISSUED AT 559 PM CST FRI DEC 20 2013
Made a few modifications to the existing TAFs. MVFR ceilings are
bouncing in and out across the area early this evening, so threw
in a TEMPO to handle that situation.
The front is just now entering the area and will pass KCGI this
evening. It will settle over KPAH and KEVV late tonight and become
stationary well into Saturday morning. Current thinking is that it
will stay southeast of KCGI and not pass KOWB through the end of this
TAF period. Added a couple of groups to handle the cha cha cha
expected at KPAH and KEVV late tonight through late Saturday
morning. Could see some strong south winds with gusts over 20kts
Saturday afternoon, except at KCGI.
Continued with the showers and VCTS through the day Saturday, with
gradually lowering ceilings through the period. IFR or lower
conditions are expected for much of the day.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH through late Saturday night FOR ILZ075>078-080>094.
MO...FLOOD WATCH through late Saturday night FOR MOZ076-086-087-100-
107>112-114.
IN...FLOOD WATCH through late Saturday night FOR INZ081-082-085>088.
KY...FLOOD WATCH through late Saturday night FOR KYZ001>022.
&&
$$
UPDATE...RJP
AVIATION...DRS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
459 AM EST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 457 AM EST SAT DEC 21 2013
SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN
STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES
ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT
LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW
WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA
UNTIL DAYBREAK ON SUNDAY.
EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN
LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF
ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK
SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT
SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF
OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW
TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP
TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO
THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC
TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT.
EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY
GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE
OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR
REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED
LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO
5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE
AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT
SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT
WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW
TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS.
CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE
THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS
ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS.
THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN
KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS
AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT
EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4
INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE
MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS
ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF
SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN.
ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1
INCH.
MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH
EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL
MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM
TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER
MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY
PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS
TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES
MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS
INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK
SUPERIOR.
SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON
THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF
LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85
AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF
WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING
WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR
SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE
INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL
CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS
MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS
THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS
WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR
SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE
EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE
SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 457 AM EST SAT DEC 21 2013
HAVE OPTED TO ISSUE A WINTER STORM WATCH FOR THE TERRAIN/LAKE
ENHANCED AREAS OF MARQUETTE/BARAGA COUNTIES AS WELL AS GOGEBIC AND
ONTONAGON COUNTIES FOR SUNDAY AND MONDAY. LONG DURATION LAKE
ENHANCED/LAKE EFFECT SNOW EPISODE LOOKING MORE POSSIBLE NOW AS THE
MODELS ARE STARTING TO COME INTO BETTER AGREEMENT INTO A MAIN LOW
TRACK THROUGH SOUTHERN MI ON SUNDAY. HOWEVER...THE COMPLEX
INTERACTION BETWEEN THE SOUTHERN STREAM ENERGY MOVING THROUGH THE
LOWER LAKES AND THE NORTHERN STREAM TROUGH MOVING INTO THE UPPER
MIDWEST MAKES THIS FORECAST CONFIDENCE STILL SOMEWHAT BELOW AVERAGE.
ONTO THE DETAILS...AS SAID ABOVE THE NWP SUITE HAVE COME INTO BETTER
AGREEMENT WITH THE MAIN LOW MOVING THROUGH SOUTHERN LOWER MICHIGAN
WITH THE SOUTHERN STREAM IMPULSE MOVING OUT OF THE PLAINS. EXPECT
SYNOPTIC MOISTURE AND LIFT TO GLANCE BY THE SOUTHEAST FORECAST AREA
SUNDAY MORNING INTO EARLY AFTERNOON AS THE COMMA HEAD/DEFORMATION
ZONE PCPN MOVES THROUGH. THIS TRACK WILL ALLOW FOR 1000-850MB WINDS
TO TURN NE AND SHOULD ALLOW FOR LAKE ENHANCEMENT TO ALSO DEVELOP IN
MARQUETTE/BARAGA COUNTIES AS WELL AS THE FAR WEST NEAR IRONWOOD.
CONSENSUS QPF FROM THE NWP SUGGEST ABOUT 0.20-0.30 INCH OF QPF NEAR
LAKE MICHIGAN AND FAR EAST ON SUNDAY...WITH MUCH LESSER AMOUNTS WELL
INLAND AWAY FROM FROM LAKE SUPERIOR. THIS ALSO SEEMS REASONABLE
GIVEN THAT 700MB MIXING RATIOS REMAIN AROUND 2 G/KG THROUGH EARLY
AFTERNOON. GIVEN THAT SOME OF THE LIFT WILL BE IN THE DGZ AREA
ACROSS THE SOUTH DURING THE DAY...WE SHOULD SEE SNOW RATIOS ACROSS
THE FAR SOUTHEAST AROUND 15-17:1 DURING THE DAY WHICH WOULD EQUATE
TO 3-5 INCHES OF SNOW BY EVENING. MOST LIKELY AN ADVISORY WILL BE
NEEDED IN THIS AREA ON SUNDAY...BUT WILL HOLD OFF SINCE THIS WILL BE
GENERALLY A 3RD PERIOD ADVY.
AS FOR AREAS CLOSER TO LAKE SUPERIOR...ALL OF THE NWP GUIDANCE SHOW
PBL WINDS STAYING NELY THROUGH THE DAY WHICH SHOULD ALLOW FOR
TERRAIN ENHANCED SNOW TO COMMENCE IN THE NE FLOW FAVORED AREAS
DESPITE THE RELATIVELY WEAK SYNOPTIC LIFT. WITH THE BEST LIFT BEING
CONFINED TO GENERALLY BELOW THE DGZ...EXPECT SNOW RATIOS BE BE
FAIRLY LOW WITH ONLY AROUND 13:1. WILL GENERALLY GO WITH 4 OR 5
INCHES AT MOST IN THESE AREAS...BUT GIVEN THE STRONG AND DEEP NE
FLOW...WOULD NOT BE SHOCKED IF QPF AND THUS SNOWFALL IS MORE ON
SUNDAY.
THEN ON SUNDAY NIGHT...DIFFERENCE START TO DEVELOP WITH THE MODELS
REGARDING THE EVOLUTION OF THE NORTHERN STREAM UPPER TROUGH. THE NAM
IS CERTAINLY THE MOST AGGRESSIVE IN CLOSING OFF THE LOW AND
SETTLING OVER THE UPPER GREAT LAKES...WHICH ALLOW FOR A STRONG
INVERTED TROUGH TO HANG BACK ACROSS THE CENTRAL GREAT LAKES THROUGH
MONDAY. MEANWHILE...THE GFS GENERALLY KEEPS THE UPPER TROUGH OPEN
AND MOVES IN THROUGH THE AREA BY MONDAY AFTERNOON. THE LATEST 00Z
ECMWF IS INTERESTING AS IT ALSO ATTEMPT TO CLOSE OFF THE LOW SUN
NIGHT BUT IS NOT NEARLY AS DEEP AS THE NAM FORECASTS.
NONETHELESS...THE ECMWF ALSO SUGGESTS THAT THERE WILL BE SOME TYPE
OF INVERTED TROUGH EXTENDING BACK INTO THE AREA THROUGH MONDAY AND
OUR LOCALLY PRODUCE ARW-WRF USING THE GFS AS BOUNDARY CONDITIONS
ALSO SUGGEST THAT THERE WILL BE A INVERTED TROUGH HANGING BACK
THROUGH MONDAY. AS SUCH...DO NOT THINK THE PBL WINDS WILL SHIFT TO
N-NW AS FAST AS THE GFS AND ECMWF SUGGEST. IN FACT...THE CURRENT
THINKING IS THAT THE WINDS WILL STAY NORTHERLY OR PERHAPS A LITTLE
EAST OF NORTH THROUGH MONDAY WITH THIS TROUGH STAYING SOUTH OF THE
AREA. WITH ALL OF THIS SAID...THE EXPECTATION IS THAT THE SNOW WILL
TRANSITION TO MORE LAKE ENHANCED VARIETY AND PERSIST RIGHT THROUGH
MONDAY BEFORE THE UPPER TROUGH SWINGS THROUGH AND ALLOWS THE WIND TO
GRADUALLY SHIFT TO THE N-NW BY MON EVENING. AS SUCH...EXPECT
MODERATE TO LOCALLY HEAVY SNOW TO CONTINUE IN MQT/BARAGA COUNTIES AS
WELL AS GOGEBIC COUNTY THROUGH THE NIGHT SUNDAY INTO MONDAY. THE
BEST LIFT RAPIDLY BECOMING ENTRENCHED IN THE DGZ SUNDAY EVENING AS
THE UPPER TEMPS DROP...EXPECT THE SNOW TO BECOME MUCH MORE FLUFFY
BUT ALSO ACCUMULATE MUCH FASTER WITH RATIOS CLOSE TO 25:1 BY MON
MORNING. SOME AREAS IN THE WATCH AREA COULD SEE ANOTHER 8-12 INCHES
OF SNOW SUN NIGHT INTO MONDAY.
INTERESTINGLY...THERE ARE SEVERAL VERY GOOD CIPS ANALOG EVENTS FOR
THIS SYSTEM. THEY ALL GENERALLY SHOW THE WATCH AREA SEEING
SIGNIFICANT 72 HOUR SNOWFALL. NOT SURE IF WE WILL SEE ANY LONGER
PERIOD OF HEAVY SNOWFALL...RATHER I AM THINKING THAT IT WILL BE
GENERALLY A PERSISTENT SNOWFALL FOR 24-36 HOURS WHICH WILL ALLOW
WARNING CRITERIA TO BE REACHED. EVEN MORE INTERESTING...DESPITE THE
FACT THAT GOGEBIC COUNTY WILL BE FURTHEST REMOVED FROM THE
SYSTEM...THE CURRENT NWP AND ALSO THE CIPS GUIDANCE SUGGEST THAT
THIS AREA COULD SEE THE MOST SNOWFALL OUT OF THIS EVENT. WE WILL
SEE...
ANY REMAINING LES SHOULD END RAPIDLY MON NIGHT/TUE MORNING AS THE
HIGH PRES RIDGE BUILDS ACROSS THE FORECAST AREA. STILL LOOKS QUITE
COLD TUE MORNING ACROSS THE WEST WITH LIGHT WINDS/CLEAR SKIES. TEMPS
10-20 BELOW NOT OUT OF THE QUESTION IN THE NORMALLY COLDER SPOTS.
THE ECMWF AND GEM ARE IN GOOD AGREEMENT IN LIGHT OVERRUNNING/WARM
ADVECTION SNOW CHRISTMAS EVE NIGHT INTO CHRISTMAS DAY ACROSS THE
ENTIRE FORECAST AREA. SOME HINTS THAT THERE MIGHT BE SOME LAKE
ENHANCEMENT OFF OF LAKE MICHIGAN TUESDAY NIGHT AND HAVE OPTED TO
CONTINUE LIKELY POPS ACROSS THE EASTERN PART OF THE FORECAST AREA
TUE NIGHT INTO CHRISTMAS DAY. SOME DIFFERENCES EMERGE THU INTO
FRIDAY REGARDING THE EVOLUTION AND THE TROUGH WITH THE ECMWF BEING
DEEPER AND FURTHER SOUTH COMPARED TO THE GFS. REGARDLESS...SENSIBLE
WEATHER SHOULD GENERALLY THE SAME WITH EITHER MODEL WITH LES IN THE
NW FAVORED SNOWBELTS CHRISTMAS NIGHT INTO THU NIGHT BEFORE
DIMINISHING ON FRIDAY AS HIGH PRES BUILDS OVERHEAD. TEMPS STILL LOOK
BELOW NORMAL THROUGH THE EXTENDED WITH 850MB TEMPS -20 TO -25C WED
NIGHT/THU WARMING TO -15 TO -20C BY FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1229 AM EST SAT DEC 21 2013
WITH ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS LINGERING OVER THE
REGION...MAINLY MVFR CIGS ARE EXPECTED THROUGH THE FCST PERIOD AT
CMX AND IWD. THERE MAY BE A PERIOD OF SNOW SHOWERS AT CMX THAT COULD
REDUCE VSBY INTO THE IFR RANGE IF A CONVERGENCE ZONE OVER THE
WESTERN LAKE SAGS INTO THE AREA. HOWEVER...CONFIDENCE IN THE TIMING
AND PLACEMENT OF THIS FEATURE IS LOW. WEAK DOWNSLOPE WESTERLY FLOW
AT SAW WILL FAVOR VFR CONDITIONS UNTIL LATE SAT AFTERNOON WHEN WINDS
VEER TO THE NNE AND UPSLOPE FLOW LEADS TO MVFR CIGS AND SOME LIGHT
SNOW SHOWERS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 457 AM EST SAT DEC 21 2013
LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS
SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS
OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW
PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER
THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW
PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE
FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE
UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH
PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A
LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES.
THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE
SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON
WEDNESDAY...WINDS WILL BECOME WESTERLY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING
FOR MIZ002-004-005-009.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...MRD
AVIATION...JLB
MARINE...JLA
AREA FORECAST DISCUSSION
NWS RALEIGH NC
309 AM EST SAT DEC 21 2013
.SYNOPSIS...WARM SOUTHERLY FLOW AROUND BERMUDA HIGH PRESSURE WILL
CONTINUE THIS WEEKEND...AHEAD OF A MOISTURE-LADEN COLD FRONT THAT
WILL CROSS OUR REGION SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 930 PM FRIDAY...
HIGH PRESSURE REMAINS ANCHORED OFF THE CAROLINA COAST THIS EVENING.
CIRRUS CONTINUES TO STREAM ACROSS THE AREA FROM THE SOUTHWEST AS
SOUTHWESTERLY UPPER LEVEL FLOW STRENGTHENS AHEAD OF A VIGOROUS STORM
SYSTEM TAKING SHAPE ACROSS THE SOUTHERN US. BASED ON SATELLITE
TRENDS...CIRRUS MAY THIN AT TIMES BUT A MAJORITY OF THE NIGHT WILL
BE MOSTLY CLOUDY. RETURN FLOW AROUND THE SURFACE HIGH MAKES STRATUS
A POSSIBILITY ONCE AGAIN...THOUGH FORECAST SOUNDINGS ARE NOT
SUGGESTING WIDESPREAD STRATUS DEVELOPMENT. THE 00Z RAOBS SHOW QUITE
A BIT MORE LOW-LEVEL MOISTURE AT KFFC THAN AT KCHS...WHICH IS WHERE
THE LOW-LEVEL FLOW IS ORIGINATING THIS EVENING. THE HRRR IS THE
MAIN MODEL SHOWING BETTER COVERAGE DEVELOPING OVER SC LATE TONIGHT
AND SPREADING ACROSS CENTRAL NC THROUGH MID-MORNING...BUT GIVEN THE
AMOUNT OF HIGH CLOUDS AND LACK OF MODEL AGREEMENT..EXPECT STRATUS
WILL BE PATCHY AND LATE TO DEVELOP. REGARDING TEMPS...CIRRUS HAS
HINDERED COOLING ALREADY THIS EVENING...AND UNLESS BETTER BREAKS IN
THE CIRRUS DEVELOP...LOWS WILL STRUGGLE TO FALL MUCH FURTHER THAN
THE UPPER 40S AND LOWER 50S IN MOST AREAS. -SMITH
SATURDAY AND SATURDAY NIGHT: THE AFOREMENTIONED COLD FRONT WILL
CONTINUE TO SLOWLY APPROACH THE REGION FROM THE WEST AS A SURFACE
WAVE OF LOW PRESSURE LIFTS FROM EASTERN TX INTO THE OHIO VALLEY
ALONG THE FRONT. WHILE LOW LEVEL CLOUD COVER SHOULD BE GREATER THAN
TODAY... AFTERNOON LOW LEVEL THICKNESS VALUES WILL INCREASE INTO THE
1380S ON SATURDAY AFTERNOON... SOME 20 METERS HIGHER THAN TODAY.
THIS SHOULD YIELD HIGH TEMPS NEAR STATISTICAL GUIDANCE (NEAR THE
WARM SIDE OF GUIDANCE)... AROUND 70 NW TO THE MID 70S
EAST/SOUTHEAST. LOWS WILL BE VERY WARM FOR THIS TIME OF YEAR WITH
AGAIN POSSIBLY SOME LOW CLOUDS. EXPECT LOWS WILL BE AROUND 60. BOTH
HIGHS AND LOWS WILL BE NEAR RECORD VALUES (RECORD HIGH MAX AND
RECORD HIGH MIN). SEE CLIMATE SECTION BELOW. WE COULD SEE SOME PRE-
FRONTAL SHOWERS AS INCREASING LOW LEVEL FLOW MAY HELP SUPPORT SOME
LIGHT SHOWERS ACROSS POINTS FROM OUR WESTERN PIEDMONT WESTWARD LATE
SATURDAY AFTERNOON INTO SATURDAY NIGHT. IF WE DO INDEED SEE ANY
PRECIP... EXPECT THE SHOWERS SHOULD BE LIGHT AND SPOTTY. FOR NOW
WILL KEEP POPS LOW FOR THIS TIME FRAME ACROSS THE WESTERN
PIEDMONT... AND NO POPS ELSEWHERE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 305 AM SATURDAY...
DEEP SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING COLD FRONT WILL TAP
INTO GULF MOISTURE... BRINGING PWS OF OVER 1.5 INCHES TO THE AREA
SUNDAY... NEAR MAX VALUES RECORDED FOR DECEMBER. HEAVY RAINFALL WILL
BE A POTENTIAL CONCERN... MAINLY OVER URBAN AREAS AS QPF REMAINS
SHORT OF FLASH FLOOD GUIDANCE AT THIS TIME. MID LEVEL LAPSE RATES
REMAIN WEAK... AND INSTABILITY LOW... SO THE SEVERE THREAT REMAINS
NEGLIGIBLE. ANY STORMS THAT DO DEVELOP MAY TAP IN TO THE STRONG 60-
65 KT LLJ AND BRING THE POTENTIAL FOR STRONG GUSTY WINDS ALONG WITH
HEAVY RAINFALL. SHEAR PROFILES WOULD BE SUPPORTIVE OF ROTATION...
HOWEVER THIS GOES STRONGLY AGAINST CLIMATOLOGY AND WITH THE
AFOREMENTIONED ENVIRONMENT... THIS IS A VERY LOW END THREAT. NEAR
RECORD HIGHS IN THE 70S.
THE COLD FRONT CROSSES THE AREA MONDAY AFTERNOON... MAKING IT TO THE
CAROLINA COAST BY 03Z TUES. HIGHS IN THE 60S. SHOWERS WILL END FROM
WEST TO EAST DURING THE EVENING HOURS. LOWS IN THE 30S WITH STRONG
COLD ADVECTION.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 307 AM SATURDAY...
UPPER LEVEL TROUGH MOVES OFF THE EAST COAST ON TUESDAY... AND THE
COLUMN DRIES SIGNIFICANTLY AS UPPER LEVEL FLOW BECOMES WESTERLY.
HIGH PRESSURE OVER THE MISSISSIPPI VALLEY ON TUESDAY WILL BUILD OVER
THE EAST COAST WEDNESDAY. HIGHS IN THE 40S ON TUESDAY WILL MODERATE
TOWARD NORMAL... IN THE 50S... WEDNESDAY THROUGH FRIDAY.
AN UPPER LEVEL TROUGH OVER CENTRAL US ON THURSDAY WILL MOVE EASTWARD
THROUGH THE END OF THE PERIOD... WITH DIFFERENCES ARISING FROM
SHORTWAVES MOVING THROUGH THE FLOW DURING THIS TIME. WILL INTRODUCE
SLIGHT CHANCE POPS FOR FRIDAY.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 128 AM SATURDAY...
VFR CONDITIONS EARLY THIS MORNING MAY TRANSITION TO A PERIOD OF
MVFR/LIFR CEILINGS BETWEEN 11-16Z...AS DIURNAL HEATING ACTS UPON AN
INCREASINGLY MOIST AIR MASS NEAR THE SURFACE. CONFIDENCE OF THIS SUB-
VFR OCCURRENCE IS ABOUT 50 PERCENT...AND MOST LIKELY AT KFAY/
KRDU/KGSO. VFR CONDITIONS WITH A BREEZY SSW WIND WILL OTHERWISE
PREVAIL THROUGH THE TAF PERIOD.
LOOKING AHEAD: THE PROBABILITY OF LOW CLOUDS/STRATUS SHOULD CONTINUE
TO INCREASE SATURDAY NIGHT/SUNDAY MORNING WITHIN STRENGTHENING
MOISTURE TRANSPORT FEED FROM THE GULF...COMPLIMENTS OF A 50KT LLJ.
SHOWERS WILL BECOME MORE NUMEROUS ACROSS THE AREA FROM WEST TO EAST
LATE SUNDAY AFTERNOON AND INTO SUNDAY NIGHT WITH WIDESPREAD SUB-VFR
CONDITIONS IN RAIN...POSSIBLY HEAVY AT TIMES...CONTINUING THROUGH
MONDAY EVENING AS A SLOW MOVING COLD FRONT PUSHES EAST THROUGH THE
AREA. VFR CONDITIONS ARE EXPECTED TO RETURN BY TUESDAY AND CONTINUE
THROUGH THE REMAINDER OF THE PERIOD.
&&
.CLIMATE...
AS OF 230 PM WEDNESDAY...
DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS:
RALEIGH/DURHAM...
HIGHHI MIN
DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011
--------------------------------------------------------------------
GREENSBORO...
HIGHHI MIN
DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984
DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011
--------------------------------------------------------------------
FAYETTEVILLE...
HIGHHI MIN
DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...26
NEAR TERM...77/SMITH
SHORT TERM...30
LONG TERM...30
AVIATION...26/CBL
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
128 AM EST SAT DEC 21 2013
.SYNOPSIS...WARM SOUTHERLY FLOW AROUND BERMUDA HIGH PRESSURE WILL
CONTINUE THIS WEEKEND...AHEAD OF A MOISTURE-LADEN COLD FRONT THAT
WILL CROSS OUR REGION SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 930 PM FRIDAY...
HIGH PRESSURE REMAINS ANCHORED OFF THE CAROLINA COAST THIS EVENING.
CIRRUS CONTINUES TO STREAM ACROSS THE AREA FROM THE SOUTHWEST AS
SOUTHWESTERLY UPPER LEVEL FLOW STRENGTHENS AHEAD OF A VIGOROUS STORM
SYSTEM TAKING SHAPE ACROSS THE SOUTHERN US. BASED ON SATELLITE
TRENDS...CIRRUS MAY THIN AT TIMES BUT A MAJORITY OF THE NIGHT WILL
BE MOSTLY CLOUDY. RETURN FLOW AROUND THE SURFACE HIGH MAKES STRATUS
A POSSIBILITY ONCE AGAIN...THOUGH FORECAST SOUNDINGS ARE NOT
SUGGESTING WIDESPREAD STRATUS DEVELOPMENT. THE 00Z RAOBS SHOW QUITE
A BIT MORE LOW-LEVEL MOISTURE AT KFFC THAN AT KCHS...WHICH IS WHERE
THE LOW-LEVEL FLOW IS ORIGINATING THIS EVENING. THE HRRR IS THE
MAIN MODEL SHOWING BETTER COVERAGE DEVELOPING OVER SC LATE TONIGHT
AND SPREADING ACROSS CENTRAL NC THROUGH MID-MORNING...BUT GIVEN THE
AMOUNT OF HIGH CLOUDS AND LACK OF MODEL AGREEMENT..EXPECT STRATUS
WILL BE PATCHY AND LATE TO DEVELOP. REGARDING TEMPS...CIRRUS HAS
HINDERED COOLING ALREADY THIS EVENING...AND UNLESS BETTER BREAKS IN
THE CIRRUS DEVELOP...LOWS WILL STRUGGLE TO FALL MUCH FURTHER THAN
THE UPPER 40S AND LOWER 50S IN MOST AREAS. -SMITH
SATURDAY AND SATURDAY NIGHT: THE AFOREMENTIONED COLD FRONT WILL
CONTINUE TO SLOWLY APPROACH THE REGION FROM THE WEST AS A SURFACE
WAVE OF LOW PRESSURE LIFTS FROM EASTERN TX INTO THE OHIO VALLEY
ALONG THE FRONT. WHILE LOW LEVEL CLOUD COVER SHOULD BE GREATER THAN
TODAY... AFTERNOON LOW LEVEL THICKNESS VALUES WILL INCREASE INTO THE
1380S ON SATURDAY AFTERNOON... SOME 20 METERS HIGHER THAN TODAY.
THIS SHOULD YIELD HIGH TEMPS NEAR STATISTICAL GUIDANCE (NEAR THE
WARM SIDE OF GUIDANCE)... AROUND 70 NW TO THE MID 70S
EAST/SOUTHEAST. LOWS WILL BE VERY WARM FOR THIS TIME OF YEAR WITH
AGAIN POSSIBLY SOME LOW CLOUDS. EXPECT LOWS WILL BE AROUND 60. BOTH
HIGHS AND LOWS WILL BE NEAR RECORD VALUES (RECORD HIGH MAX AND
RECORD HIGH MIN). SEE CLIMATE SECTION BELOW. WE COULD SEE SOME PRE-
FRONTAL SHOWERS AS INCREASING LOW LEVEL FLOW MAY HELP SUPPORT SOME
LIGHT SHOWERS ACROSS POINTS FROM OUR WESTERN PIEDMONT WESTWARD LATE
SATURDAY AFTERNOON INTO SATURDAY NIGHT. IF WE DO INDEED SEE ANY
PRECIP... EXPECT THE SHOWERS SHOULD BE LIGHT AND SPOTTY. FOR NOW
WILL KEEP POPS LOW FOR THIS TIME FRAME ACROSS THE WESTERN
PIEDMONT... AND NO POPS ELSEWHERE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 250 PM FRIDAY...
STRONG WARM AIR ADVECTION CONTINUES AHEAD OF THE SLOWLY APPROACHING
COLD FRONT...WITH RECORD HIGH TEMPERATURES ON SUNDAY. SHOWER
ACTIVITY WILL BE GRADUALLY SPREADING INTO THE WESTERN PIEDMONT
THROUGH THE DAY...WITH CHANCE POPS IN THE EAST BY EVENING.
STRENGTHENING IN THE LOW LEVEL JET (>50KTS) AND FAVORABLE UPPER
DIFFLUENCE WILL BE OFFSET BY MEAGER INSTABILITY...WITH NEAR
NEGLIGIBLE CAPE SUNDAY...WILL CONTINUE ONGOING ISOLATED THUNDER.
HIGHS WILL REACH MID TO UPPER 70S OVER MOST OF THE AREA.
LIKELY TO CATEGORICAL POPS WILL BE THE RULE SUNDAY NIGHT AND MONDAY
AS THE FRONT MOVES SLOWLY ACROSS THE AREA. SIMILARLY...FORCING IS
STRONG IN THE FRONTAL ZONE...OFFSET BY WEAK MID LEVEL LAPSE RATES SO
WILL CONTINUE ISOLATED THUNDER...ALLOWING FOR STRONGER WORDING AS
THE SCENARIO APPROACHES AND THE TIMING CAN BE PINNED DOWN MORE
TIGHTLY. MINS WILL BE VERY MILD SUNDAY NIGHT...MID 50S TO LOWER
60S...GIVING A HEADSTART ON MONDAYS HIGHS...WHICH WILL PEAK IN THE
60S AS THE FRONT MOVES TO A POSITION EAST OF THE AREA BY MONDAY
AFTERNOON. SHOWERS WILL LINGER IN THE EAST THROUGH PERHAPS MIDNIGHT
MONDAY NIGHT...OTHERWISE COLD AIR ADVECTION WILL BE SURGING INTO THE
AREA MONDAY NIGHT...WITH SKIES CLEARING FROM THE WEST AND TEMPS
FALLING INTO THE 30S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 25O PM FRIDAY...
CLEAR AND MUCH COOLER TUESDAY AND CHRISTMAS DAY AS HIGH PRESSURE
MIGRATES ACROSS THE OHIO VALLEY AND RIDGES DOWN THE ATLANTIC COAST.
HIGHS WILL BE IN THE LOW AND MID 40S BOTH DAYS. MORNING LOWS WILL BE
MOSTLY IN THE MID 20S CHRISTMAS MORNING.
THERE IS CONSIDERABLE UNCERTAINTY IN THE LATE WEEK PERIOD AS THE
UPCOMING COLD AIR DAMMING SCENARIO WILL ENCOURAGE DEVELOPMENT OF A
TROF ALONG THE COAST. THIS COULD LEAD TO SOME CYCLOGENESIS AND
UNSETTLED WEATHER IN THE EASTERN THIRD OF THE STATE BY FRIDAY. AT
THIS POINT AIRMASS MODIFICATION LOOK TO ALLOW HIGHS TO SNEAK BACK UP
TOWARDS THE CLIMATOLOGICAL RANGE OF UPPER 40S TO MID 50S THURSDAY
AND FRIDAY.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 128 AM SATURDAY...
VFR CONDITIONS EARLY THIS MORING MAY TRANSITION TO A PERIOD OF
MVFR/LIFR CEILINGS BETWEEN 11-16Z...AS DIURNAL HEATING ACTS UPON AN
INCREASINGLY MOIST AIR MASS NEAR THE SURFACE. CONFIDENCE OF THIS SUB-
VFR OCCURENCE IS ABOUT 50 PERCENT...AND MOST LIKELY AT KFAY/
KRDU/KGSO. VFR CONDITIONS WITH A BREEZY SSW WIND WILL OTHERWISE
PREVAIL THROUGH THE TAF PERIOD.
LOOKING AHEAD: THE PROBABILITY OF LOW CLOUDS/STRATUS SHOULD CONTINUE
TO INCREASE SATURDAY NIGHT/SUNDAY MORNING WITHIN STRENGTHENING
MOISTURE TRANSPORT FEED FROM THE GULF...COMPLIMENTS OF A 50KT LLJ.
SHOWERS WILL BECOME MORE NUMEROUS ACROSS THE AREA FROM WEST TO EAST
LATE SUNDAY AFTERNOON AND INTO SUNDAY NIGHT WITH WIDESPREAD SUB-VFR
CONDITIONS IN RAIN...POSSIBLY HEAVY AT TIMES...CONTINUING THROUGH
MONDAY EVENING AS A SLOW MOVING COLD FRONT PUSHES EAST THROUGH THE
AREA. VFR CONDITIONS ARE EXPECTED TO RETURN BY TUESDAY AND CONTINUE
THROUGH THE REMAINDER OF THE PERIOD.
&&
.CLIMATE...
AS OF 230 PM WEDNESDAY...
DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS:
RALEIGH/DURHAM...
HIGHHI MIN
DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011
--------------------------------------------------------------------
GREENSBORO...
HIGHHI MIN
DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984
DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011
--------------------------------------------------------------------
FAYETTEVILLE...
HIGHHI MIN
DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...26
NEAR TERM...77/SMITH
SHORT TERM...26/13
LONG TERM...MLM
AVIATION...26/CBL
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
440 AM EST SAT DEC 21 2013
.SYNOPSIS...
FRONT APPROACHES FROM THE WEST TODAY...PASSES AS COLD FRONT SUNDAY.
SNOW SHOWERS POSSIBLE MONDAY NIGHT INTO TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SURFACE BOUNDARY HAS BEEN SHIFTING EAST SLOWLY THROUGH THE NIGHT AND
CURRENTLY RUNS FROM CENTRAL TEXAS NORTHEAST TO THE WESTERN SHORES
LAKE ERIE. ONE WAVE IS NEAR DETROIT AND LIFTING NE...DRIVING PRECIP
BISECTING OHIO. NEXT WAVE IS LIFTING INTO ARKANSAS WHICH IS MAYBE
JUST A BIT FASTER THAN THE LOWER RES MODELS...BUT REPRESENTED FAIRLY
WELL BY HIGHER RES MODELS LIKE HRRR AND RAP. SO TRENDED TOWARDS
THESE HIGHER RES MODELS FOR POPS THIS MORNING AS THE WAVE MOVES INTO
THE LOWER OHIO RIVER VALLEY WITH LIKELY POPS INTO SE OHIO. ANOTHER
WAVE IS STARTING TO TAKE SHAPE IN EASTERN TEXAS WHICH WILL DRIVE
ANOTHER AREA OF HIGHER POPS INTO SE OHIO TONIGHT. HAVE A BREAK
BETWEEN THE TWO WAVES...BUT STILL HAVE SLIGHT CHANCE POPS EAST AND
CHANCE POPS WEST THIS EVENING. THIS WILL ALSO BE THE WAVE THAT GETS
THE BOUNDARY MOVING EAST AGAIN...SO HAVE THE FRONT JUST WEST OF CWA
BORDER BY 12Z SUNDAY. NOT A WHOLE LOT OF INSTABILITY TODAY...BUT
850MB FLOW PUSHES 70-80KTS LATE THIS AFTERNOON INTO TONIGHT ACROSS
WESTERN CWA...MAINLY IN SE OHIO AND NE KENTUCKY. THIS MATCHES SPCS
SLIGHT RISK...AND WHILE THUNDER IS NOT EXPECTED...STRONGER SHOWERS
SHOULD STILL BE ABLE TO TAP INTO THIS AND PRODUCE SOME ENHANCED
OUTFLOW WINDS. WILL MENTION POTENTIAL FOR STRONG OUTFLOWS IN HWO FOR
SE OHIO AND NE KY COUNTIES. DO HAVE SLIGHT CHANCE OF THUNDER IN THE
GRIDS JUST AHEAD OF THE FRONT EARLY SUNDAY MORNING...ANTICIPATING
STRONG DYNAMIC FORCING. STILL...NOT EXPECTING WIDESPREAD
THUNDER...BUT A RUMBLE OR TWO CANNOT BE RULED OUT.
PLACEMENT OF HIGHEST QPF STILL LOOKS TO STAY WEST OF CWA...JUST
CLIPPING NW CORNER LATE THIS AFTERNOON INTO TONIGHT...SO WILL NOT
MAKE ANY CHANGES TO FLOOD WATCH AT THIS POINT.
LITTLE TO NO CHANGE MADE TO HIGHS TODAY...GOING WELL ABOVE NORMAL
FOR THE WINTER SOLSTICE. DID WARM UP LOWS TONIGHT A COUPLE
DEGREES...AND WENT WITH A NON-DIURNAL TREND WITH NEARLY STEADY TEMPS
THROUGH THE EARLY MORNING OUT AHEAD OF THE COLD FRONT. NOT THAT ITS
AN OFFICIAL CLIMATE STATISTIC...BUT COULD BE CLOSE TO SETTING SOME
RECORD HIGH MINIMUMS.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SFC LOW WILL BE QUICKLY PUSHING NORTHEAST FROM ROUGHLY CENTRAL
INDIANA TO THE EASTERN GREAT LAKES BTWN 12Z SUN AND 00Z MON.
ATTENDANT COLD FRONT ALSO PROGGED TO BE JUST OUTSIDE THE WESTERN
ZONES BY 12Z SUN AND WILL BE QUICKLY PUSHING ACROSS AS WELL. OVERALL
FORECAST GENERALLY STILL ON TRACK...BUT DID SLOW DOWN THE
PROGRESSION OF PRECIP ACROSS THE FORECAST AREA FROM WEST TO EAST BY
ABOUT TWO-THREE HOURS...WITH THE HIGHEST CHANCE OVER THE WEST ZONES
BY 12Z...CENTRAL ZONES BY 15Z...AND MOST PRECIP EAST OF THE I79
CORRIDOR BY 18Z. CONSENSUS OF MODEL OUTPUT STILL DEPICTING ABOUT
50KTS AT 925MB AND 70-80KTS AT 850MB. SPC HAS EXPANDED ITS SLIGHT
RISK AREA OF SEVERE THUNDERSTORMS TO INCLUDE MOST OF THE SE OHIO AND
NE KY COUNTIES. THE THREAT FOR A BRIEF SVR WIND GUST EXISTS FOR MOST
LOCATIONS PRETTY MUCH ANYWHERE ALONG AND WEST OF I79 SUNDAY MORNING
PRIMARILY AS THE MAIN CONVECTIVE LINE MARCHES ACROSS...BUT CERTAINLY
THE SE OHIO COUNTIES ARE MOST PRONE TO THIS POSSIBILITY AS THE ASSOC
LOWS AT 925MB AND 850MB MOVE NORTHEAST WITH THE SFC LOW. STILL
EXPECTING GENERALLY A HALF INCH OR SO OF PRECIP WITH SOME HIGHER
AMOUNTS AHEAD OF AND WITH THE FRONT. FOR MAX TEMPS...MOS GUIDANCE
CONTINUING TO INSIST ON LOWER 70S. WENT LOWER THAN THIS HOWEVER WITH
ONGOING CLOUDS AND PRECIP DURING THE MORNING HOURS AS COLD ADVECTION
IS BEGINNING...SHOULD STILL BE IN THE LOW/MID 60S. MAY ACTUALLY SEE
A FEW BREAKS IN THE CLOUDS ACROSS THE WESTERN ZONES BY 18Z-21Z...BUT
BY THIS TIME 925MB AND 850MB TEMPS CONTINUE TO LOWER TO READINGS
WHICH WOULD ONLY SUPPORT PERHAPS THE MID 60S ACROSS THOSE LOCATIONS.
PRECIP WILL WIND DOWN DURING THE AFTERNOON HOURS EVEN FOR THE
MOUNTAINS AS DEEP LAYER MOISTURE CONTINUES EASTWARD. ANOTHER
DEVELOPING WAVE ALONG THE FRONT HOWEVER WILL QUICKLY BRING A RETURN
TO PRECIP CHANCES MAINLY BTWN 06Z-12Z MON. THIS NEXT SFC WAVE WILL
SLOW/DELAY THE COLD PUSH OF AIR INTO THE AREA. IN FACT...HAVE HOURLY
TEMPS STILL IN THE LOWER 50S AROUND 06Z-08Z FOR LOWLANDS EAST OF
I79...WITH MUCH COOLER TEMPS ACROSS THE SE OHIO ZONES. AS THIS NEXT
SFC LOW ALSO PASSES TO THE NORTHEAST...WINDS WILL FINALLY COME
AROUND TO THE NORTHWEST ALLOWING FOR THE COLD AIR TO FILTER FULLY
INTO THE AREA. CODED UP SOMEWHAT OF A NON-DIURNAL TEMP CURVE FOR
MONDAY...WITH SOME MODEST RECOVERY OF TEMPS ACROSS THE FAR NW
ZONES...NEARLY STEADY TEMPS ACROSS THE CENTRAL AREAS...AND TEMPS
CONTINUING TO SLOWLY DROP DURING THE DAY ACROSS THE EASTERN
MOUNTAINS. SKIES SHOULD REMAIN MOSTLY CLOUDY TO CLOUDY FOR MOST WITH
THIS COLD ADVECTION...BUT AGAIN MAY SEE SOME LATE DAY BREAKS FOR THE
CENTRAL AND WEST ZONES.
A COLD NIGHT IS IN STORE FOR THE AREA MONDAY NIGHT/TUE MORNING.
SHOULD SEE MORE CLOUDS AND ANOTHER INCREASING CHANCE OF LIGHT
SNOW/FLURRIES...ESPECIALLY ACROSS THE NORTH...TOWARDS THE DAWN HOURS
TUE AS THE UPPER TROUGH FINALLY BEGINS TO SHIFT EASTWARD...WITH
TROUGH AXIS PROGGED TO BE LOCATED OVER LAKE HURON SOUTH INTO OHIO BY
12Z TUE. LOWERED MINS JUST A BIT INTO THE LOWER 20S WITH LOW
DEWPOINTS...BUT STAYED ABOVE THE LOWEST GUIDANCE WITH AFOREMENTIONED
CLOUD COVER AND A CONTINUED 10-15KT BREEZE IN THE BOUNDARY LAYER.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
SOME UPSLOPE SNOW POSSIBLE MONDAY NIGHT INTO TUESDAY AS COLD AIR
MOVES INTO THE REGION ON NORTHWEST FLOW. HIGH PRESSURE THEN BUILDS
IN FOR CHRISTMAS DAY. USED THE ECMWF MEAN FOR THURSDAY AND
FRIDAY...WHICH WOULD SHOW A FRONT MOVING THROUGH ON THURSDAY. BIG
QUESTION ON FRIDAY IS HOW MUCH COLD AIR RESIDES BEHIND THE FRONT AND
WHETHER ANY SNOW SHOWERS WILL BE ASSOCIATED WITH IT. WENT DRY FOR
NOW AS PER MEAN...BUT CONFIDENCE IS NOT HIGH.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
EXPECT A MIX OF MVFR TO VFR CEILINGS THROUGH THE REST OF THE
NIGHT...WITH THE BEST CHANCE OF SUSTAINED MVFR ALONG AND WEST OF
THE OHIO RIVER. COULD ALSO GET ISOLATED SHOWERS ALONG AND WEST OF
THE OHIO RIVER THROUGH THE EARLY MORNING HOURS...BUT BULK OF THE
ACTIVITY WILL REMAIN WEST OF THE FORECAST AREA. SHOULD BE MAINLY
VFR TODAY...WITH A FEW LIGHT SHOWERS WEST. THE CHANCES OF RAIN
INCREASE THROUGH TONIGHT AS SURFACE BOUNDARY APPROACHES FROM THE
WEST WITH DIPS INTO MVFR POSSIBLE LATE.
STRONG SW FLOW ALOFT WILL CONTINUE THROUGH THE TAF PERIOD WHICH WILL
RESULT IN SURFACE WINDS GUSTING INTO THE 15 TO 20 KT RANGE. WITH
FLOW REMAINING AT THE SURFACE...SHOULD NOT REACH LLWS CRITERIA.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY...
FORECAST CONFIDENCE: MEDIUM TO HIGH.
ALTERNATE SCENARIOS: TIMING OF MVFR MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SAT 12/21/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H M M M M H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 06Z SUNDAY...
IFR IN RAIN LATE SATURDAY NIGHT INTO SUNDAY. IFR POSSIBLE IN SNOW
SHOWERS MONDAY NIGHT INTO TUESDAY.
&&
.HYDROLOGY...
MODEL CONSENSUS SHOWS MAIN SWATH OF PRECIP JUST TO THE WEST OF THE
HSA. FOR THE WATCH AREA...EXPECT THE HEAVIEST RAINS TO OCCUR LATE
SATURDAY INTO SATURDAY NIGHT. 1 TO 2 INCHES ARE POSSIBLE WITH
LOCALLY HIGHER AMOUNTS. THE MAIN THREAT OF FLOODING IS FOR SMALL
STREAMS AND CREEKS...ESPECIALLY IN LOW LYING AND POOR DRAINAGE
AREAS. RISES ON THE MUSKINGUM ARE EXPECTED AS WELL. EVEN THOUGH THE
HEAVIEST RAINFALL IS EXPECTED TO FALL JUST OUTSIDE HSA...RUNOFF AND
STREAM FLOW WILL CONTINUE TO FLOW INTO THE WATCH AREA AND CAUSE
ELEVATED LEVELS ON STREAMS AND CREEKS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...FLOOD WATCH FROM 7 AM EST THIS MORNING THROUGH SUNDAY MORNING
FOR OHZ066-067.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/MZ/50
NEAR TERM...MZ
SHORT TERM...50
LONG TERM...RPY
AVIATION...MZ
HYDROLOGY...MZ
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1155 PM CST FRI DEC 20 2013
.AVIATION...
AN UPPER LEVEL DISTURBANCE OVER THE NORTHERN PART OF THE MEXICAN
STATE OF CHIHUAHUA IS MOVING EAST TOWARD WEST TEXAS AS OF 0530Z.
LIFT ASSOCIATED WITH THIS SYSTEM IS RESULTING IN A LARGE AREA OF
RAIN WITH SOME EMBEDDED THUNDERSTORMS MAINLY WEST OF A K0F2
/BOWIE/ TO KILE /KILLEEN/ LINE. IN THE MEANTIME A COLD FRONT HAS
NEARLY STALLED SOUTHEAST OF A LINE FROM KJDD /QUITMAN/ TO TEMPLE
/KTPL/. TEMPERATURES AT THE METROPLEX TAF SITES AT 11 PM /05Z/
WERE IN 33 TO 39 DEGREES...AND WILL FALL TO 32 TO 35 DEGREES
OVERNIGHT. SEVERAL ACARS/TAMDAR SOUNDINGS BETWEEN 04Z AND 05Z
SHOW A FEW HUNDRED FEET OF SUB-FREEZING AIR BETWEEN 1200 AND 1800
FEET WITH TEMPERATURES MAXING OUT IN THE MID 50S AROUND 3000
FEET. AS THE RAIN INCREASES OVERNIGHT...THE RELATIVELY WARM RAIN
DROPS SHOULD ALLOW TEMPERATURES TO ACTUALLY RISE A DEGREE OR TWO.
THUS HAVE KEPT ALL OF THE PRECIPITATION LIQUID IN THE TAFS. A FEW
THUNDERSTORMS ARE ALSO POSSIBLE OVERNIGHT INTO SATURDAY
MORNING...FOR NOW HAVE JUST PLACED A TEMPO TSRA FOR THE MOST
LIKELY TIME...10-14Z. IFR CONDITIONS WILL PREVAIL THROUGH MUCH OF
THE DAY SATURDAY...WITH A GRADUAL IMPROVEMENT TO MVFR BY MID
AFTERNOON AND SKIES SHOULD CLEAR DURING THE EVENING.
58
&&
.UPDATE...
THE LATEST WATER VAPOR LOOP SHOWS THE UPPER LOW CENTER TRUDGING
EAST AND GETTING CLOSER TO WEST TEXAS. LIFT IS ON THE INCREASE
ACROSS NORTH AND CENTRAL TEXAS...AND PRECIPITATION COVERAGE IS EXPECTED
TO RAMP UP OVER THE NEXT FEW HOURS. ISOLATED CONVECTION HAS BEGUN
IN THE WARM SECTOR WITH A FEW LIGHTNING STRIKES SHOWING UP NEAR
CANTON. MEANWHILE...THE SHALLOW ARCTIC AIRMASS HAS BARRELED
FARTHER SOUTH INTO CENTRAL TEXAS AND THE 32 DEGREE ISOTHERM HAD
DROPPED SOUTH OF POSSUM KINGDOM DURING THE PAST HOUR. WILL ADJUST
LOWS DOWNWARD ACCORDINGLY...WHILE ADDING A FEW MORE COUNTIES TO THE
RAIN/FREEZING RAIN MIX AREA WEST AND NORTHWEST OF THE DALLAS-FORT
WORTH METROPLEX...WITH LITTLE OR NO ACCUMULATIONS STILL EXPECTED.
30
&&
.PREV DISCUSSION... /ISSUED 411 PM CST FRI DEC 20 2013/
21Z SUBJECTIVE SURFACE ANALYSIS SHOWED A STRONG COLD FRONT IN
PLACE ALONG A LINE FROM PARIS TO DALLAS TO HAMILTON. THE
TEMPERATURE GRADIENT ALONG THIS BOUNDARY WAS QUITE IMPRESSIVE WITH
A 70 DEGREE TEMPERATURE THAT WAS OBSERVED AT GREENVILLE...A 49
DEGREE TEMPERATURE AT MCKINNEY AND A 39 DEGREE TEMPERATURE AT
DENTON. THIS FRONT WAS STILL MOVING SOUTHEAST AT 15 MPH AT THE
TIME OF THIS DISCUSSION. A 20Z AIRPLANE SOUNDING FROM DALLAS LOVE
FIELD INDICATED THAT THE FRONT WAS SHALLOW IN NATURE...WITH THE
FRONTAL INVERSION ONLY EXTENDING UP ABOUT 1500 FEET ABOVE GROUND
LEVEL. THE FRONT IS STILL EXPECTED TO STALL OUT OVER THE FAR
SOUTHEASTERN CWA THIS EVENING...IN RESPONSE TO CYCLOGENESIS
INITIATED BY THE APPROACH OF A POWERFUL UPPER LEVEL STORM SYSTEM.
THIS UPPER LEVEL STORM SYSTEM WAS OBSERVED OVER BAJA CALIFORNIA AT
20Z BASED ON WATER VAPOR SATELLITE IMAGERY. OUT AHEAD OF THIS
UPPER LEVEL STORM SYSTEM...WATER VAPOR SATELLITE IMAGERY SHOWED A
NICE CONTINUOUS BAND OF SUB-TROPICAL PACIFIC MOISTURE STREAMING
NORTHEAST OVER NORTHERN MEXICO AND THE SOUTH PLAINS. THE HIGH
TERRAIN OF NORTHERN MEXICO WILL SCOUR OUT ALL OF THE LOW TO MID-
TROPOSPHERIC MOISTURE ASSOCIATED WITH THIS SUBTROPICAL PLUME...BUT
THE MID TO UPPER LEVEL MOISTURE WILL CONTRIBUTE TO MOISTURE DEPTH
OVER THE REGION AS THE UPPER LEVEL STORM SYSTEM MOVES ACROSS THE
AREA TONIGHT INTO TOMORROW MORNING.
THROUGH TONIGHT...THE MOST TROUBLESOME FORECAST PROBLEM IN THE
SHORT TERM FORECAST IS THAT ALL FORECAST GUIDANCE IS DOING A
REMARKABLY POOR JOB RESOLVING THE STRENGTH OF THE SHALLOW COLD AIR
ASSOCIATED WITH/BEHIND THE COLD FRONT. WHILE ALL GUIDANCE IS DOING
A POOR JOB RESOLVING SURFACE TEMPERATURES NORTH OF THE COLD
FRONT...THE RAP IN PARTICULAR IS DIFFICULT TO PROCESS BECAUSE IT
CONTINUES TO INITIALIZE THE COLD AIR...BUT PERSISTENTLY BRINGS
SURFACE TEMPERATURES UP 5-7 DEGREES AT FORECAST HOUR 1 DESPITE
PERSISTENT COLD AIR ADVECTION AND CLOUD COVER. THIS WOULD BE MORE
OR LESS A NUISANCE IF THE TEMPERATURES HAD NO POTENTIAL TO HAVE AN
IMPACT ON PRECIPITATION TYPE IN THIS FORECAST. FOR INSTANCE...AT
BOWIE...THE 21Z OBSERVATION HAD A TEMPERATURE OF 32 DEG F. THE RAP
INITIALIZES THIS AT 34 DEGREES...WHICH IS NOT TOO FAR OFF...BUT
THEN GOES AHEAD TO FORECAST A TEMPERATURE OF 40 DEGREES BY 22Z.
WITH WIDESPREAD RAINFALL DEVELOPING OVER THE REGION RIGHT
NOW...AND EXPECTED TO PERSIST THIS EVENING INTO THE OVERNIGHT
HOURS...THIS ERROR IN RESOLVING NEAR SURFACE TEMPERATURES IS QUITE
PROBLEMATIC. THEREFORE...AT THIS TIME...WITH NO GUIDANCE AVAILABLE
ACTUALLY RESOLVING THE STRENGTH OF THIS COLD AIR...THE
PRECIPITATION TYPE FORECAST FOR TONIGHT WAS COMPLETED USING
OBSERVATIONAL TRENDS...RECENT FORECAST EVENTS AND INTUITION.
AT THIS TIME EXPECT THAT TEMPERATURES ALONG AND NORTHWEST OF A
GAINESVILLE TO GRAHAM LINE ARE MOST LIKELY TO FALL TO 32 DEGREES
THIS EVENING...LIKELY HOLDING STEADY THROUGH MUCH OF THE OVERNIGHT
HOURS. AS A RESULT...EVEN IF WE SEE RAIN AT 31 TO 32 DEGREES FOR
SEVERAL HOURS...THE CURRENT THINKING IS THAT WE WILL NOT SEE ANY
ICE ACCUMULATION...EXCEPT PERHAPS ON TREE TOPS OR THE TOPS OF
EXPOSED METAL SURFACES. THE REASONS FOR THIS ARE AS FOLLOWS:
1. BEFORE THE FRONT...WE HAVE EXPERIENCED A FEW DAYS OF ABOVE
NORMAL TEMPERATURES. GROUND/ROAD TEMPERATURES ARE WELL ABOVE
FREEZING WHICH WILL NOT ALLOW FOR ICE ACCUMULATION.
2. THE DEPTH OF THE ELEVATED WARM LAYER IS ALMOST 8 TIMES AS DEEP
AS THE DEPTH OF THE COLD/SUB-FREEZING LAYER. RAIN FALLING IN THIS
ENVIRONMENT WILL LIKELY HAVE A TEMPERATURE ABOVE FREEZING WHEN IT
REACHES THE SURFACE. THAT IS THE TEMPERATURE OF THE FALLING RAIN
DROPS ARE LIKELY TO BE ABOVE FREEZING...THIS IS ALSO NOT CONDUCIVE
TO ICE ACCUMULATION.
3. ALL GUIDANCE INDICATES PERSISTENT WARM AIR ADVECTION THROUGH
12Z SATURDAY ABOVE THE COLD FRONTAL INVERSION. THE WARM LAYER IS
VERY LIKELY TO MAINTAIN ITS DEPTH AND STRENGTH...WHILE RELATIVELY
WARM RAIN DROPS MAY ACTUALLY SHRINK THE DEPTH OF THE SHALLOW COLD
AIR OVERNIGHT.
AS A RESULT...WILL NOT BE HIGHLIGHTING FREEZING RAIN IN THE
FORECAST AT THIS TIME...DESPITE THE SURFACE OBSERVATION AT BOWIE
AT 32 DEGREES SEEMINGLY SHOWING AN ICE STORM ON OUR DOORSTEP. IT
LOOKS LIKE THE DEPTH OF THE COLD AIR WILL ONLY SUPPORT ICE
ACCUMULATION FARTHER NORTH...WELL INTO OKLAHOMA BASED ON
OBSERVATIONAL ANALYSIS AND DFW AREA AIRCRAFT SOUNDINGS.
DESPITE ALL THAT HAS BEEN DISCUSSED ABOUT THE SHALLOW COLD AIR
PROBLEM...THERE WERE ACTUALLY NO SIGNIFICANT CHANGES MADE TO THE
PREVIOUS FORECAST WHICH REMAINS LARGELY ON TRACK. THE BAJA UPPER
LEVEL LOW IS STILL EXPECTED TO MOVE OVER THE SOUTH PLAINS TOMORROW
MORNING...SPREADING STRONG LARGE SCALE FORCING FOR ASCENT OVER THE
REGION TONIGHT THROUGH TOMORROW MORNING. NEARLY ALL GUIDANCE
INDICATES THAT THE UPPER LOW WILL BECOME INCREASINGLY NEGATIVELY
TILTED AS IT MOVES OUT OVER TEXAS...DEEPENING AS IT MOVES OVER THE
CWA. THE STRONGEST FORCING FOR ASCENT LOOKS TO MOVE OVER THE CWA
IN THE 09 TO 15Z TIME FRAME...WHICH SHOULD ALSO REPRESENT OUR
WINDOW FOR THE BEST COVERAGE AND HEAVIEST PRECIPITATION RATES
DURING THIS EVENT.
FOR THIS EVENING...THE COLD FRONT PUSHING SOUTH THROUGH MOST OF
THE CWA WILL SIMPLY HELP TO STEEPEN LOW-LEVEL ISENTROPIC SURFACES
AS CYCLOGENESIS RAMPS UP NEAR DEL RIO RESULTING IN AN INCREASE OF
THE STRENGTH OF THE LOW TO MID-LEVEL WIND FIELD. THIS SHOULD
RESULT IN A SPREAD OF THE COVERAGE OF ONGOING RAIN SHOWER
ACTIVITY FROM WEST TO EAST ACROSS THE CWA. AS THE UPPER LEVEL LOW
APPROACHES...ASSUMING IT BECOMES MORE NEGATIVELY TILTED AS
ADVERTISED...WE SHOULD SEE AN ENHANCEMENT OF MID-LEVEL LAPSE RATES
WITH SOME UPPER-LEVEL COLD AIR ADVECTION OVER THE PERSISTENT LOW-
LEVEL WARM AIR ADVECTION REGIME. THIS WILL RESULT IN AN INCREASED
CHANCE OF ISOLATED THUNDERSTORMS EMBEDDED IN THE RAIN SHOWER
ACTIVITY FROM SUNSET TO MIDNIGHT. ALL OF THIS ACTIVITY SHOULD
REMAIN ELEVATED IN NATURE...AND POSES VERY LITTLE SEVERE WEATHER
THREAT AS A RESULT. RAINFALL RATES WILL BE ENHANCED...AND
THEREFORE SOME LOCALIZED HEAVY RAINFALL IS POSSIBLE.
AFTER MIDNIGHT...AS MENTIONED ABOVE...THE BEST LARGE SCALE FORCING
FOR ASCENT IS EXPECTED TO BUILD ACROSS THE CWA FROM WEST TO EAST
DURING THIS TIME RESULTING IN THE STRONGEST AND MOST WIDESPREAD
CONVECTION AND PRECIPITATION FOR THE REGION. BASED ON THE POSITION
OF THE COLD FRONT AT THAT TIME...WE DO HAVE A WINDOW FOR SURFACE
BASED SEVERE STORMS BASED ON CONVECTIVE PARAMETERS ADVERTISED IN
THE MAJORITY OF GUIDANCE. LOCATIONS ALONG AND SOUTHEAST OF
WHEREVER THE COLD FRONT STALLS OUT WOULD BE THE ONLY LOCATIONS
WHERE SURFACE BASED SEVERE STORMS WOULD BE POSSIBLE. FORECAST
CONVECTIVE PARAMETERS INDICATED SURFACE BASED CAPE VALUES OF
AROUND 1000 J/KG WITH 0-3 KM CAPE VALUES OF AROUND 100 J/KG AND
DEEP LAYER SHEAR VALUES IN EXCESS OF 50 KTS.
THESE VALUES ARE SUPPORTIVE OF A LOW-TOPPED SUPER CELLULAR STORM
MODE...WHICH COULD RESULT IN LARGE HAIL...DAMAGING WIND OR
ISOLATED TORNADOES. THIS THREAT IS MODERATED BY STRONG FORCING
WHICH MAY MAKE AN ISOLATED STORM MODE DIFFICULT TO REALIZE...AND
STRONG CLOUD LEVEL WINDS THAT WILL LIKELY TAKE STORMS THAT DEVELOP
ALONG THE FRONT...OVER/NORTH OF THE FRONT SHORTLY AFTER
INITIATION. REGARDLESS...WILL BE WATCHING FOR WHERE THE FRONT
STALLS OUT TONIGHT AS LOCATIONS NEAR AND TO THE SOUTHEAST OF THE
BOUNDARY ARE THE MOST LIKELY TO SEE SEVERE WEATHER. FURTHER
NORTHWEST...STRONG STORMS REMAIN POSSIBLE...HOWEVER EVEN ELEVATED
SUPERCELLS ARE ONLY GOING TO PROVIDE A THREAT FOR MARGINALLY
SEVERE HAIL...SO THE OVERALL SEVERE WEATHER THREAT NORTHWEST OF
THE FRONT DIMINISHES GREATLY.
FOR ANYWHERE ACROSS NORTH TEXAS...LOCALLY HEAVY RAINFALL IS
POSSIBLE WHICH MAY RESULT IN SOME LOCALIZED FLASH FLOODING ISSUES
OVER THE NEXT 24 HRS. WITH THE SUB-TROPICAL PACIFIC MOISTURE FEED
IN PLACE...AND LOW-LEVEL WARM MOIST ADVECTION EXPECTED TO RAMP UP
IN INTENSITY OVER THE SHALLOW COLD FRONT...NEARLY ALL GUIDANCE
INDICATES THAT PWAT VALUES WILL BE UP AROUND 1.5 INCHES ACROSS
NORTH AND CENTRAL TEXAS AS THE UPPER LOW SPREADS STRONG FORCING
OVER THE REGION. 1.5 INCH PRECIPITABLE WATER VALUES RANK AS PLUS 3
STANDARD DEVIATION FOR NORTH TEXAS AT THIS TIME OF YEAR. THIS
EXCEPTIONALLY DEEP MOISTURE COMBINED WITH FAVORABLE DYNAMICS FOR
WIDESPREAD PRECIPITATION SUPPORT A LOCALIZED HEAVY RAINFALL THREAT
WITH AN ATTENDANT LOCALIZED FLOODING THREAT TONIGHT INTO TOMORROW
MORNING. DID NOT ISSUE A FLASH FLOOD WATCH AT THIS TIME BECAUSE
OUR PRIMARY WINDOW FOR HEAVY RAINFALL IS ONLY EXPECTED TO BE ON
THE ORDER OF 6 HOURS OR SO. IF STRONG FORCING WAS EXPECTED TO BE
IN PLACE FOR A LONGER PERIOD OF TIME...THE THREAT OF WIDESPREAD
FLOODING WOULD BE MUCH GREATER AND A WATCH WOULD HAVE BEEN ISSUED.
AT THIS TIME THE THREAT OF FLOODING IS EXPECTED TO REMAIN
LOCALIZED AND MAINLY CONFINED TO LOW LYING/COMMONLY FLOODED AREAS.
HEAVY PRECIPITATION IS EXPECTED TO COME TO AN END FROM SOUTHWEST
TO NORTHEAST SATURDAY AFTERNOON AS A STRONG MID-LEVEL DRY SLOT
PUNCHES OVER THE REGION. LIGHT RAIN MAY PERSIST ACROSS THE AREA
SATURDAY AFTERNOON...BUT EVEN THIS WILL BE SCOURED OUT BY SUNSET.
REMAINDER OF THE FORECAST...NO SIGNIFICANT CHANGES WERE MADE TO
THE PREVIOUS FORECAST AS MOST OF THE ACTIVITY IN THE FORECAST IS
IN THE FIRST 24 HOURS. HIGHLIGHTS OF THE REMAINDER OF THE FORECAST
INCLUDE:
1. ADDED A MENTION OF SPRINKLES/LIGHT RAIN TO THE FORECAST ALONG
THE COLD FRONT THAT IS EXPECTED TO PUSH SOUTH THROUGH THE CWA ON
SUNDAY MORNING. WILL HAVE TO WATCH TEMPERATURES CLOSELY SUNDAY
MORNING AS THIS FRONT ROLLS THROUGH...HOWEVER ALL GUIDANCE
INDICATES TEMPERATURES JUST ABOVE FREEZING WITH THIS VERY LIGHT
PRECIPITATION.
2. WE SHOULD BE DRY EARLY NEXT WEEK...LEADING UP TO CHRISTMAS DAY.
TEMPERATURES WILL SLOWLY WARM THROUGH CHRISTMAS...ALTHOUGH HIGHS
ARE EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEK AHEAD.
3. AN UPPER LEVEL STORM SYSTEM MAY RESULT IN SCATTERED RAIN
SHOWERS ACROSS THE REGION ON CHRISTMAS DAY. AT THIS TIME
TEMPERATURES ARE EXPECTED TO BE WELL ABOVE FREEZING...SO NO
SIGNIFICANT IMPACTS ARE EXPECTED AT THIS TIME.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 36 47 36 48 29 / 100 100 10 10 5
WACO, TX 42 62 37 50 30 / 80 100 10 10 5
PARIS, TX 41 45 36 47 26 / 100 100 10 10 10
DENTON, TX 33 44 34 47 26 / 100 100 10 10 5
MCKINNEY, TX 35 44 35 46 25 / 100 100 10 10 5
DALLAS, TX 37 46 38 48 30 / 100 100 10 10 5
TERRELL, TX 41 47 37 47 28 / 100 100 10 10 5
CORSICANA, TX 46 54 39 48 30 / 80 100 10 10 5
TEMPLE, TX 41 63 39 52 31 / 80 100 10 10 5
MINERAL WELLS, TX 31 49 34 48 24 / 100 90 10 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1135 PM CST FRI DEC 20 2013
.DISCUSSION...
UPDATED AVIATION SECTION.
&&
.AVIATION...
AGAIN CHALLENGING 06Z TAF PACKAGE. CURRENTLY SURFACE ANALYSIS
SHOWS SURFACE LOW DEVELOPING OVER CENTAL TX. AN AREA OF RAIN WITH
EMBEDDED THUNDERSTORMS IS ASSOCIATED WITH THIS LOW AND FRONTAL
ZONE. WATER VAPOR SHOWING UPPER LOW AND ASSOCIATED JET MAKING ITS
WAY INTO WEST TEXAS. ANOTHER AREA OF RAIN WITH EMBEDDED THUNDER
WAS ASSOCIATED WITH THIS FEATURE. EAST OF THESE TWO RAIN AREAS
WERE SOME VERY LIGHT SHOWERS OCCURRING AS MOISTURE ADVECTS IN OFF
THE GULF AND WITH A SMALL AMOUNT OF CAPE BELOW THE CAPPING
INVERSION.
TAKING ALL THESE SYSTEMS INTO ACCOUNT...EXPECT CAPPING
INVERSION TO KEEP PRECIPITATION INITIALLY IN THE FORM OF VERY LIGHT
RAIN SHOWERS...BUT WITH COOLING ALOFT AND LIFT ASSOCIATED WITH
APPROACHING UPPER LOW...GREATER THREAT OF HEAVIER RAIN AND
THUNDERSTORMS TO FIRST REACH CLL AROUND DAYBREAK...THE HOUSTON
AREA AIRPORTS BETWEEN MID MORNING AND EARLY AFTERNOON....AND
GALVESTON WITH SURFACE FRONTAL PASSAGE MID AFTERNOON. SITUATION IS
MOST COMPLEX FOR CLL AS FIRST RAIN AREA WITH EMBEDDED THUNDER
COULD BRUSH THAT AREA IN THE PRE DAWN HOURS. SOME POTENTIAL FOR
GUSTY WINDS WITH THE STRONGER STORMS AS LOW LEVEL JET VERY STRONG.
CEILINGS MAINLY MVFR BUT WITH AREAS OF OR TEMPO IFR AS ARE
CURRENTLY OCCURING. 46
&&
.PREV DISCUSSION... /ISSUED 910 PM CST FRI DEC 20 2013/
UPDATE...
THE ONLY CHANGE ON THIS SHIFT WAS TO ADJUST SHORT TERM POPS/WX TO
BETTER COME IN-LINE WITH ONGOING TRENDS. DURING THE 8 PM HOUR...THE
COLD FRONT IS WORKING ITS WAY SOUTHWARD AND NOW PUSHING INTO THE
SOUTHERN COUNTIES OF DFW`S CWA. DOWNSTREAM OF THIS MAIN BOUNDARY...
VERY LIGHT RAIN SHOWERS OR DRIZZLE AFFECTING OUR FA...MOVING NORTH
WITHIN A VERY PERSISTENT SWATH OF 40 KT JUST-OFF-THE-SURFACE SOUTHERLY
(LLJ) FLOW. A VERY WARM AND MOIST OVERNIGHT WITH SEA FOG LOWERING
MARITIME VISIBILITIES TO UNDER A COUPLE OF MILES AT TIMES...LOCALLY
DENSE AT A MILE OR UNDER ESPECIALLY IF NEARSHORE SOUTHERLIES BACK
A BIT MORE EASTERLY WITH TIME. MINIMUM TEMPERATURES WILL BE A
DEGREE OR TWO OFF 70 F...WITH SIGNIFICANTLY GREATER CONVECTIVE
CHANCES FROM AROUND 21/09Z ONWARD OVER THE NORTHERN FORECAST
AREA. THE HRRR DISPLAYING THE FORMATION OF MORE DISCRETE CELLS
FROM SHORTLY AFTER MIDNIGHT THROUGH SUNRISE. OUR MOISTENED DOWNSTREAM
ENVIRONMENT IS HIGHLY SHEARED AFFORDING HIGH HELICITY AND
SIGNALING THAT MANY UPDRAFTS WILL ROTATE. SPC HAS THE NORTHERN
THIRD OF THE CWA HIGHLIGHTED IN SLIGHT RISK TO ACCOUNT FOR THIS
EARLY MORNING THROUGH EARLY AFTERNOON THREAT FOR STRONG
CELLS...POSSIBLY WITHIN A BROKEN WEST-MOVING-EAST QLCS...REACHING
SEVERE LIMITS. DAMAGING WINDS AND TORNADOES WILL BE THE MAIN
THREATS THROUGH MID-SATURDAY. 31
PREV DISCUSSION... /ISSUED 554 PM CST FRI DEC 20 2013/
DISCUSSION...
UPDATED AVIATION FOR OOZ TAFS.
AVIATION...
TRICKY FORECAST WITH CEILING HEIGHTS OVERNIGHT...AND TIMING OF THE
THUNDERSTORM THREAT BEING THE BIGGEST CHALLENGES. ALREADY SEEING
CIGS IN THE 1000 TO 1200 FOOT RANGE SOME LOCATIONS. GLS SOCKED IN
WITH SEA FOG AND HALF MILE VISIBILITY. RADAR SHOWING LIGHT RETURNS
INCREASING ASSOCIATED WITH VERY LIGHT SHOWERS OR SPRINKLES.
OVERNIGHT AM IN GENERAL GOING WITH MVFR CIGS PREVAILING...NEAR
CURRENT LEVELS BUT THINK THERE WILL BE A WINDOW OF CIGS BLO 1000
FEET AT MOST AIRPORTS AND HAVE INDICATED THAT WITH A TEMPO GROUP
OVERNIGHT MOST SITES. THUNDERSTORM THREAT WILL BE SATURDAY MORNING
FOR CLL AND UTS...MORE MIDDAY AND EARLY AFTERNOON FOR CXO AND IAH
AND AFTERNOON FOR HOU...SGR...LBX AND GLS. MOST LIKELY SCENARIO
WILL BE NUMEROUS LIGHT SHOWERS UNDERNEATH THE CAP BEFORE
THEN...THEN THE DEVLOPMENT OF A LINE OF STORMS THAT WILL MOVE
QUICKLY OVER THE AREA. THREAT SHOULD BE EAST OF THE TAF SITES BY
LATE TOMORROW AFTERNOON. 46
PREV DISCUSSION... /ISSUED 406 PM CST FRI DEC 20 2013/
SLIGHT RISK OF SEVERE WEATHER TONIGHT INTO SATURDAY...
DISCUSSION...
SFC ANALYSIS HAS COLD FRONT PUSHING THROUGH DFW METROPLEX HEADED
TOWARDS A TYLER/WACO LINE. FRONT SHOULD PUSH CLOSE TO A COLLEGE
STATION TO CROCKETT LINE TONIGHT BUT LIKELY STALL JUST NORTH.
MOISTURE HAS DEEPENED WITH SFC DEWPOINTS IN THE 70S. SEA FOG MAY
BE AN ISSUE ALONG THE COAST SO WILL HAVE ANOTHER DENSE FOG
ADVISORY FOR THE COAST TONIGHT. SHOWERS SHOULD INCREASE OVERNIGHT
WITHIN MAY MOISTURE AXIS THROUGH THE AREA. SO REALLY NO CHANGES IN
THE FORECAST THROUGH TONIGHT.
UPPER AIR ANALYSIS AND WATER VAPOR IMAGERY SHOW STRONG UPPER LOW
MOVING ACROSS NORTHERN MEXICO AND S ARIZONA. UPPER LOW SHOULD
REACH EL PASO AND BIG BEND AREA BY 12Z SAT WITH HEIGHT FALLS OVER
TX AND LARGE SCALE ASCENT SPREADING INTO THE AREA.
THIS SHOULD SUPPORT THUNDERSTORM ACTIVITY ALONG THE FRONTAL
BOUNDARY TONIGHT WHICH MAY STALL JUST NORTH OF COLLEGE STATION.
SPC HIGHLIGHTS SMALL SEVERE WEATHER PROBS FOR THIS SCENARIO. AS
THE UPPER LOW MOVES EAST...EXPECT ANOTHER LINE OF STORMS TO FORM
ALONG APPROACHING PACIFIC FRONT WHICH SHOULD PUSH INTO THE ARE
DURING THE MORNING. THE 12Z TX TECH WRF AND 4KM WRF-ARW SHOW THIS
LINE DEVELOPING IN THE PRE-DAWN HOURS AND MOVING INTO THE AREA.
BASICALLY LEFT 60/70 POPS FOR OVERNIGHT TIME FRAME TO ACCOUNT FOR
THIS POSSIBILITY BUT FEEL MOST THUNDERSTORM ACTIVITY WILL BE
DURING THE DAY SATURDAY.
SATURDAY WILL BE MORE SPRING LIKE WITH REGARDS TO THUNDERSTORM
ACTIVITY THAN THE FIRST DAY OF WINTER. MODELS ARE ALL ON THE SAME
PAGE WITH HOW THE UPPER LOW MOVES TOWARDS C/NE OK BY 00Z SUN. MAIN
CONCERN WILL BE WHETHER STRONG MID LEVEL CAP WILL ERODE. 850MB
TEMPS LOOK TO WARM NEAR 16-20C ON THE GFS BY 18Z SAT. THE NAM
ERODES THE CAP QUITE A BIT DURING THIS TIME. THE PROBLEM IS THAT
NONE OF THE MODELS REALLY BRING GOOD PVA OVER THE AREA AND KEEP IT
NORTH OF THE AREA. OMEGA FIELDS SUPPORT BREAKING THE CAP BUT HAVE
SEEN SEVERAL TIMES BEFORE WHERE THE CAP HOLDS PRETTY STRONG. MAIN
QUESTION WILL BE WHEN EXACTLY THE CAP WILL BREAK. IF THE NAM HOLDS
TRUE THEN QUITE POSSIBLE TO GET DISCRETE SUPERCELLS AHEAD OF THE
DEVELOPING QLCS. HAVE NO QUESTION ABOUT OTHER SEVERE PARAMETERS AS
DEEP LAYER SHEAR AND LOW LEVEL SHEAR WILL BE OFF THE CHARTS GIVEN
STRONG LLJ AND UPPER LEVEL JET. UPPER LEVEL JET STREAK DYNAMICS
WITH RIGHT ENTRANCE REGION MOVING OVER THE AREA MAY JUST BE ENOUGH
TO ERODE THE CAP. ALL POINTS TO BASICALLY 15-21Z BEING THE FAVORED
TIME FOR SEVERE STORMS MORE LIKELY 15-18Z. OTHER LIMITING FACTOR
WILL BE INSTABILITY AS COOLING ALOFT MAY NOT BE QUITE ENOUGH TO
PUSH CAPE TO ABOVE 1500 J/KG. THINK 1000 J/KG MORE LIKELY AND THIS
STILL COULD BE ENOUGH TO SUPPORT ROBUST UPDRAFTS FOR ROTATION.
THINK SPC DAY 2 OUTLOOK IS GOOD BUT REALLY DO NOT WANT TO UNDER-
ESTIMATE THE CAP AND UPPER LEVEL DYNAMICS BEING JUST ENOUGH OUT OF
PHASE THAT A LINE OF STRONG STORMS RESULTS. STILL QUITE A BIT OF
UNCERTIANTY IN THE FORECAST BUT ENOUGH CONFIDENCE THAT THE SEVERE
POTENTIAL SHOULD BE HIGHLIGHTED.
TRUE COLD FRONT WILL PUSH THROUGH DURING THE DAY SUNDAY SO TEMPS
MAY BE A TOUCH WARMER THAN EXPECTED. HOWEVER MON/TUE AND EVEN
CHRISTMAS DAY WILL CERTAINLY FEEL LIKE WINTER AROUND SE TX.
GFS/ECMWF STILL TRYING TO SORT OUT RETURN FLOW CHRISTMAS DAY INTO
THURSDAY. WILL KEEP SOME 20 POPS DURING THAT TIME BUT REALLY DO
NOT HAVE A GOOD FEEL FOR PRECIP. LIKELY DEPENDS ON WHERE STRONGEST
ISENTROPIC LIFT SETS UP AND MODELS DIFFER BY SEVERAL HUNDERED
MILES ON WHERE THAT IS. ALSO NOTICED THAT ECMWF IS STRONGER WITH
COLD FRONT LATE NEXT THAN THE GFS WHICH HAS SEEMED TO BACK OFF.
OVERALL KEPT TREND OF ECMWF KEEPING TEMPS COLDER.
39
MARINE...
PATCHY FOG REMAINS PROBLEMATIC IN AND AROUND GALVESTON BAY WITH
VISIBILITIES FALLING TO BELOW ONE MILE AT TIMES. WITH CONDITIONS
EXPECTED TO DETERIORATE THROUGH THE EVENING HAVE ISSUED A MARINE
DENSE FOG ADVISORY FOR GALVESTON BAY AND THE ADJACENT NEARSHORE
WATERS THROUGH EARLY SATURDAY. SMALL CRAFT ADVISORY WILL REMAIN IN
PLACE FOR THE OFFSHORE WATERS THROUGH THE OVERNIGHT HOURS WITH
CAUTION FLAGS RAISED ACROSS THE NEARSHORE WATERS AND BAYS AS WINDS
INCREASE THIS EVENING.
38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 69 72 45 62 31 / 50 80 10 10 0
HOUSTON (IAH) 70 77 49 69 35 / 40 70 30 10 0
GALVESTON (GLS) 65 71 55 68 42 / 20 60 30 10 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH SATURDAY AFTERNOON
FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20
NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
DENSE FOG ADVISORY UNTIL 5 AM CST SATURDAY FOR THE FOLLOWING
ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO FREEPORT
OUT 20 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM CST SATURDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
60 NM.
&&
$$
DISCUSSION...99
AVIATION/MARINE...99
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
343 AM CST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CST SAT DEC 21 2013
CONCENTRATING ON REFINING THE WINTER STORM DETAILS AND IMPACTS IN
THE FORECAST SUITE. IN GENERAL...THERE HAVE BEEN MINOR CHANGES TO
THE FORECAST FOR THIS STORM...AND IT STILL LOOKS ON TRACK.
THIS SYSTEM IS WHY MANY METEOROLOGISTS WENT INTO WEATHER. THE
POWER RIGHT NOW FROM THIS SYSTEM IN THE SOUTHERN U.S. IS
REMARKABLE. GOES WATER VAPOR CLEARLY SHOWING THE STRONG TROUGH
OVER SRN NEW MEXICO WITH STRONG QVECTOR CONVERGENCE AND FORCING
OVER WESTERN TEXAS /GREAT TRANSVERSE WAVES ON IR IMAGERY/. SURFACE
PRESSURES ARE FALLING IN ARKANSAS ABOUT 1MB/HR...AND THE LOW-LEVEL
JET IS INCREASING INTO A FRONTAL ZONE DEFINED BY 34F TO 72F ACROSS
NRN AR...AND CONVECTION WITH C-G LIGHTNING. DEWPOINTS IN THE WARM
SECTOR ARE IN THE LOWER 70S ILLUSTRATING THE AMOUNT OF MOISTURE
DRAWING INTO THIS SYSTEM.
THIS STORM HAS ALL THE DYNAMICS FOR A MAJOR PRECIPITATION
PRODUCER...STRONG AND COMPACT QVECTOR CONVERGENCE/DIVERGENCE
DIPOLE...UPPER LEVEL JET ENTRANCE REGION DIVERGENCE ALOFT /JET MAX
OVER SRN CANADA OF 180KTS FORECAST/...STRONG FRONTOGENETIC FORCING
AT 600-700MB /GREAT FOR SNOW PRODUCTION/. SO...THE QUESTION IS
WHERE WILL THE SNOW BAND LAY DOWN...WITHIN A COUNTY...AND TRYING
TO UNDERSTAND WHY THE MODELS ARE STILL DIFFERENT.
SINCE 20.12Z...THE NAM HAS REALLY CHANGED ITS TUNE TO A WET AND WEST
AND MORE IN-LINE SOLUTION WITH THE GFS/EC/CANADIAN...AND HAS BEEN
CONSISTENT WITH ITS OUTCOMES IN THE LAST 3 RUNS. THE HIGHEST
PRECIPITATION BAND IS CONSISTENT WITH THE 20.12 ECMWF AND LATEST
CANADIAN/GFS RUNS...ROUGHLY FROM KDBQ-KDLL AND SOUTHEAST. THE
21.12Z ECMWF HAS SHIFTED A BIT EAST NOW. OVERALL...THE ECMWF SEEMS
TO HAVE THE BEST 500MB DEPICTION INDICATING A STRONG NEARLY CLOSED
LOW SHIFTING NORTHEAST...WHILE THE 21.00Z GFS VORTICITY IS
DISORGANIZED AND CHANNELED...AND THE GFS SURFACE LOW FURTHEST
EAST. WPC MODEL GUIDANCE DISCUSSION PREFERRED AN ECMWF SOLUTION OR
NON-NCEP ENSEMBLE. BOTTOM LINE IS THEY ARE ALL VERY REASONABLE ON
QPF/SNOW AMOUNTS EXCEPT POSSIBLY THE NAM THAT SEEMS TO SPREAD TOO
MUCH PRECIPITATION NORTHWEST...SUGGESTING IMPACTS FURTHER WEST
INTO MN/IA...A WIDE ADVISORY SNOW AREA. WHILE THIS SOLUTION CANNOT
BE DISCOUNTED...THE NORTHERN STREAM INFLUENCE/DEFORMATION SHOULD
LIMITED THE WESTWARD EXTENT....AND THE UPPER JET DIVERGENCE SEEMS
TO SUPPORT A MORE WI/IL SOLUTION FOR THE BEST LIFT /EAST/.
SNOW FORECAST REMAINS CONSISTENT...BUT HAVE MADE A SLIGHT TWEAK
WEST...MAYBE ONE-HALF A COUNTY. THE WARNING IS WELL PLACED...BUT
HAVE DECIDED TO INCLUDE JUNEAU AND ADAMS COUNTY IN CENTRAL WI.
ALSO HAVE ADDED FAYETTE COUNTY TO THE WARNING AFTER COLLABORATION
WITH DMX. HAVE CHANGED THE REMAINING WATCH COUNTIES TO AN ADVISORY
AND BASED ON THE 3 INCH SNOW TOTAL LINE...BUILT A FEW OTHER
COUNTIES INTO THE ADVISORY WESTWARD.
TIMING...
LATEST RUNS OF THE RAP INDICATE THE POSSIBILITY OF PRECIPITATION
TO THE IL/WI BORDER BY 6 PM TONIGHT. THIS IS A BIT FASTER TREND
THAN THE OTHER MODELS WHICH BEGIN SNOW AROUND 8-9PM IN THE SOUTH.
EVEN THOUGH CONSENSUS IS FOR ONSET IN THE SOUTH AT 8-9 PM HAVE
LEFT THAT START TIME 6 PM FOR NOW. THAT CAN BE ADJUSTED IF NEEDED.
HOWEVER...HAVE ADJUSTED START TIME IN CENTRAL WI TO 03Z/9PM FOR
THE WARNING...BASICALLY THE I-90 CORRIDOR. THE HEAVIEST SNOW WILL
FALL FROM ABOUT 3 AM TO 9 AM.
IMPACTS...
BECAUSE THIS STORM HAS SHORTER DURATION...WARNING SNOW
AMOUNTS WILL NOT BE UNUSUAL IN THE FORECAST AREA WITH 6 TO 8
INCHES EXPECTED AND 2 TO 5 IN THE ADVISORY. WINDS WILL BE
STRONGEST IN SERN MN INTO NERN IA...15 TO 25 MPH. THIS LEADS TO
THE UPGRADE TO WARNING IN FAYETTE AS A BIT MORE BLOWING IS
EXPECTED THERE WITH 4-5 INCHES OF SNOW.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CST SAT DEC 21 2013
SNOW SLOWLY DIMINISHES TO FLURRIES OR VERY LIGHT ACCUMULATING SNOW
SUNDAY AFTERNOON. HOWEVER...THE NORTHERN STREAM DAKOTAS SHORTWAVE
TROUGH WILL BE MOVING IN WITH THE SURGE OF ARCTIC AIR SUNDAY
NIGHT. THIS FORCING AND COLD ADVECTION WILL PROVIDE SOME
INSTABILITY AND LIFT FOR AN EXTENSION OF LIGHTLY ACCUMULATING
SNOW. SUNDAY NIGHT AND MONDAY MORNING COULD BRING ANOTHER 1-2
INCHES OF FLUFFY SNOW...WITH THE 2 INCH AMOUNTS NEAR AND NORTHEAST
OF I-94. THIS IS A LARGER CHANGE IN THE FORECAST.
AN ACTIVE PATTERN CONTINUES THROUGH THE WEEK WITH WARM ADVECTION
SNOWFALL POSSIBLE CHRISTMAS EVE AND ANOTHER VIGOROUS TROUGH
POSSIBLY THURSDAY WITH ANOTHER COLD AIR SURGE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1140 PM CST FRI DEC 20 2013
MVFR TO IFR CEILINGS WILL LINGER THROUGH TOMORROW AS ONE LOW
PRESSURE SYSTEM TRACKS TO THE EAST IN THE GREAT LAKES WHILE A
SECOND...MORE POTENT LOW IS DEVELOPING IN THE SOUTHERN PLAINS.
THIS SECOND LOW WILL BRING SNOW INTO THE REGION OVERNIGHT ON
SATURDAY...BUT NOT UNTIL AFTER THE END OF THIS TAF PERIOD. WHILE
CONDITIONS MAY BRIEFLY IMPROVE ON SATURDAY...THEY SHOULD DROP
AGAIN SATURDAY NIGHT AS LOW LEVEL MOISTURE INCREASES ACROSS THE
REGION. WINDS WILL REMAIN LIGHT THROUGH MUCH OF THE DAY BEFORE
GOING NORTHEAST AND INCREASING TO AROUND 10-15KTS SATURDAY NIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR WIZ053.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR WIZ054-055-061.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST
SUNDAY FOR WIZ034-041-042.
WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY
FOR WIZ043-044.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR MNZ096.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR IAZ010-011-019.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR IAZ029-030.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
824 AM MST SAT DEC 21 2013
.AVIATION...DENSE FOG AT KDEN WITH RVRS MAINLY BELOW 1000 FT. THE
FOG HAS LIFTED AT KBJC WITH ONLY LIGHT FOG AT KAPA...AND EROSION
SHOULD CONTINUE FROM THE WEST/WEST-SOUTHWEST AS SURFACE WINDS
ARE TRENDING THAT WAY. EXACT TIMING OF DISSIPATION AT KDEN IS
DIFFICULT DUE TO HIGH CLOUDS MOVING OVER THE TOP...BUT AT THIS
TIME EXPECT SOME IMPROVEMENT STARTING 16Z AND TOTAL EROSION
EXPECTED BY 17Z-18Z. WILL CONTINUE TO MONITOR.
&&
.PREV DISCUSSION... /ISSUED 528 AM MST SAT DEC 21 2013/
UPDATE...
SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO
HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO
FORT MORGAN TO DENVER LINE.
AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED
DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER
AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z.
PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/
SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM
FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT
SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW
FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS
NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE
IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE
OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD
INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER
WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN.
OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH
COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND
OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S
OVER THE PLAINS.
BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND
ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW
INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES
ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND
NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN
INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN
AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO.
LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF
THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT
DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS.
AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG
NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF
SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND
PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY
MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER
PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE
MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF
MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY
EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING
SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO.
GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE
PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL
INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY
EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST
CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED
POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY
EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z
WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW
ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH
VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS
SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES
AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE
LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST
FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES
OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY
MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR...
EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER.
THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO
PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS
MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH
MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST
COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR
TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG
ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND
ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT.
WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN
PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF
THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT
WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT
CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS
DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND
FRIDAY.
AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY
SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE
HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE
MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE
DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE
POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE
MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS
THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP.
FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT
WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF
LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF
ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH
IMPROVING CONDITIONS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM MST THIS MORNING FOR COZ038>040-
043>045.
WINTER WEATHER ADVISORY FROM NOON TODAY TO NOON MST SUNDAY FOR
COZ031-033-034.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
528 AM MST SAT DEC 21 2013
.UPDATE...
&&
.SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO
HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO
FORT MORGAN TO DENVER LINE.
.AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED
DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER
AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z.
&&
.PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/
SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM
FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT
SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW
FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS
NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE
IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE
OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD
INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER
WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN.
OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH
COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND
OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S
OVER THE PLAINS.
BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND
ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW
INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES
ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND
NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN
INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN
AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO.
LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF
THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT
DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS.
AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG
NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF
SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND
PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY
MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER
PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE
MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF
MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY
EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING
SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO.
GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE
PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL
INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY
EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST
CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED
POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY
EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z
WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW
ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH
VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS
SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES
AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE
LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST
FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES
OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY
MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR...
EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER.
THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO
PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS
MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH
MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST
COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR
TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG
ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND
ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT.
WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN
PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF
THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT
WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT
CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS
DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND
FRIDAY.
AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY
SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE
HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE
MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE
DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE
POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE
MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS
THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP.
FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT
WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF
LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF
ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH
IMPROVING CONDITIONS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM MST THIS MORNING FOR COZ038>040-
043>045.
WINTER WEATHER ADVISORY FROM NOON TODAY TO NOON MST SUNDAY FOR
COZ031-033-034.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
330 AM MST SAT DEC 21 2013
.SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM
FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT
SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW
FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS
NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE
IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE
OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD
INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER
WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN.
OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH
COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND
OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S
OVER THE PLAINS.
BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND
ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW
INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES
ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND
NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN
INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN
AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO.
.LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF
THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT
DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS.
AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG
NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF
SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND
PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY
MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER
PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE
MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF
MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY
EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING
SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO.
GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE
PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL
INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY
EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST
CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED
POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY
EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z
WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW
ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH
VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS
SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES
AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE
LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST
FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES
OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY
MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR...
EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER.
THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO
PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS
MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH
MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST
COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR
TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG
ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND
ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT.
WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN
PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF
THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT
WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT
CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS
DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND
FRIDAY.
&&
.AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY
SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE
HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE
MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE
DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE
POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE
MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS
THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP.
FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT
WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF
LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF
ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH
IMPROVING CONDITIONS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM NOON TODAY TO NOON MST SUNDAY FOR
COZ031-033-034.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS ALBANY NY
626 AM EST SAT DEC 21 2013
.SYNOPSIS...
A SERIES OF LOW PRESSURE WAVES WILL PROPAGATE ALONG A NEARLY
STATIONARY FRONT FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK
AND NORTHERN NEW ENGLAND THROUGH TONIGHT. A MUCH STRONGER STORM
WILL MOVE OUT OF THE OHIO VALLEY SUNDAY ALONG THIS FRONT. IN ITS
WAKE COLDER AIR WILL FILER BACK INTO THE REGION FOR THE FIRST HALF
OF THE WEEK. THE WEEKEND WILL FEATURE MILD TEMPERATURES FOR
DECEMBER...PERIODS OF RAIN BECOMING WIDESPREAD LATE SATURDAY INTO
SUNDAY WITH FREEZING RAIN ALONG THE NORTHERN TIER OF NEW YORK AND
NEW ENGLAND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 626 AM EST...A STALLED SURFACE FRONTAL BOUNDARY IS SITUATED
ACROSS FAR NORTHERN NEW YORK. AS A WEAK WAVE OF LOW PRESSURE MOVES
ALONG THIS BOUNDARY...THE FRONT WILL DROP SOUTH ACROSS THE
NORTHERN PORTION OF OUR CWA LATER TODAY. PERIODS OF RAIN WILL
ACCOMPANY THIS FRONTAL BOUNDARY THROUGHOUT THE DAY TODAY. THE
LATEST 3KM HRRR SUGGESTS ONE BATCH OF RAINFALL WILL MOVE ACROSS
THE REGION THIS MORNING...WITH A MORE STEADIER AND HEAVIER BATCH
OF RAIN TO OCCUR LATER THIS AFTERNOON AND INTO TONIGHT. TEMPS HAVE
WARMED UP ABOVE FREEZING ACROSS THE ENTIRE CWA...SO THERE IS NO
LONGER ANY THREAT FOR FZRA THIS MORNING.
A STRONG SOUTHERLY FLOW AT LOW LEVELS HAS ALLOWED TEMPS TO RANGE
FROM THE UPPER 30S TO UPPER 40S. DESPITE OVERCAST SKIES...TEMPS
WILL CONTINUE TO BE ABOVE NORMAL TODAY...AS A SOUTHERLY FLOW
CONTINUES TO THE SOUTH OF THE FRONTAL BOUNDARY. MAX TEMPS WILL
GENERALLY BE IN THE 40S...WITH SOME TEMPS NEAR 50 IN THE MID
HUDSON VALLEY.
TONIGHT...THE FRONTAL BOUNDARY WILL BECOME STALLED ACROSS
ADIRONDACKS...AS ANOTHER AND MUCH STRONGER WAVE OF LOW PRESSURE
BEGINS TO APPROACH FROM THE MISSISSIPPI AND TENNESSEE VALLEY
REGION. THERE WILL BE A STRONG THERMAL GRADIENT ASSOCIATED WITH
THIS BOUNDARY...WHICH WILL ALLOW FOR STRONG ISENTROPIC LIFT. 850 HPA
TEMPS WILL RANGE FROM AROUND +5 C OVER THE WESTERN ADIRONDACKS THIS
EVENING TO AS HIGH AS +14 DEGREES C BY LATE TONIGHT OVER THE
SOUTHEASTERN CORNER OF THE CWA.
WITH A STRONG AREA OF HIGH PRESSURE OVER WESTERN QUEBEC...THERE WILL
BE A VERY COLD AND DENSE AIR MASS SITUATED JUST NORTH OF OUR AREA.
THE STRONG AGEOSTROPHIC FLOW AT 925 HPA WILL ALLOW THIS COLD DENSE
AIR TO GET PULLED SOUTHWARD DOWN THE CHAMPLAIN VALLEY TONIGHT. AS A
RESULT...SFC TEMPS ACROSS THE LAKE GEORGE AREA WILL DROP BELOW
FREEZING ONCE AGAIN. WITH A WIDESPREAD RAIN EXPECTED
OVERNIGHT...THIS RAIN WILL FREEZE ON CONTACT...RESULTING IN FREEZING
RAIN ACROSS NORTHEASTERN WARREN AND NORTHERN WASHINGTON COUNTIES.
WE HAVE ISSUED A FREEZING RAIN ADVISORY TO ACCOUNT FOR THIS...WITH
A FEW TENTHS OF AN INCH POSSIBLE IN THESE LOCATIONS. THERE MAY BE
A FEW POCKETS OF FREEZING RAIN ACROSS THE FAR NORTHWESTERN
ADIRONDACKS...MAINLY NORTH OF OLD FORGE AND NORTHWEST OF INDIAN
LAKE...BUT ANY ICE ACCRETION IN THESE AREAS WILL BE VERY LIMITED
AND LOCALIZED. ELSEWHERE...A WIDESPREAD MODERATE TO LOCALLY HEAVY
RAIN WILL OCCUR FROM ABOUT THE CAPITAL REGION ON NORTH OVERNIGHT.
SOME RAIN WILL OCCUR ACROSS SOUTHERN AREAS AS WELL...ALTHOUGH THE
BEST PRECIP WILL BE LOCATED CLOSER TO THE TIGHT BAROCLINIC ZONE
ACROSS THE NORTHERN PORTION OF THE CWA. OUTSIDE OF THE LAKE GEORGE
AREA...TEMPS LOOK TO HOLD STEADY AND/OR SLOWLY RISE
OVERNIGHT...WITH MIN TEMPS OCCURRING EARLY IN THE PERIOD AND
RANGING FROM THE MID 30S TO MID 40S.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
BY SUNDAY MORNING STATIONARY FRONT REMAINS DRAPED FROM SW NYS TO
NR PWM. OVERRUNNING HAD BEEN THE PRIMARY DRIVER OF UVM AND PCPN
THROUGH SAT NT ALONG WITH AGEO CIRC ASSOC WITH RIGHT ENTRANCE RGN
OF INTENSE 300HPA JET. RAINS WILL HAVE OVERSPREAD THE ENTIRE FCA
MUCH OF THE NIGHT. BY SUN MRNG GFS HAS OVER 2 IN QPF IN ADIRONDACKS
TO LESS THAN 1 TENTH IN MID HUD VLY WITH A SOMEWHAT MORE GENEROUS
MAX IN THE NAM OF 2.6 IN.
SUNDAY A SHARP SHORT WV EJECTS INTO THE UPR MIDWEST...TRIGGERING A
MUCH DEEPER CYCLOGENESIS IN THE OHIO VLY THAN THE WAVES THAT HAD
BEEN RIPPLING ALONG THE STATIONARY FRONT TO THIS POINT. THE LOW
DEEPENS AS IT MOVES ACROSS FCA SUN. IN ADDITION THE PREVIOUSLY ACTING
ISENTROPIC LIFT AND JET DYNAMICS...CONVERGENCE WITH THE LOW AND
ALONG THE WMFNT WILL ENHANCE A BURST OF PCPN SUN WORKING WITH RICH
AIR MASS AND PW OF 1.25 IN OR BETTER.
SUNDAY THE MDLS DUMP ANOTHER TENTH OF AN INCH QPF IN MID HUD VLY
WITH ANOTHER TO 1.25 INCHES IN ADRNDKS. THE GEM HAS SIMILAR
NUMBERS WITH A MAX SHIFTED SLIGHTLY TO THE N OF US MDLS AND A
FRONTAL POSITION 50 OR SO MILES N.
IN SUMMARY QPF VALUES FM DETERMINISTIC MDLS ARE ANOTHER 0.5 TO 1.0
INCHES GREATER THAN PVS QPF. TOTALS ARE ON THE ORDER FROM 0.25 MID
HUD VLY TO 3 PLUS INCHES IN ADRNDKS. THE ECMWF AND GEM ARE ON THE
LIGHTER SIDE WITH A MAX QPF CLOSER TO 2 INCHES TOTAL. ADD TO THAT
THE SNOW PACK MELT. BY SUNDAY SNOW PACK WILL BE RIPE OR RIPENING
N. MOST WILL BE GONE IN THE SE. IN THE SE 1.0 LIQ OF SNOW PACK AND
A HALF AN INCH OF QPF SHOULDN`T PUSH RIVERS OUT OF THEIR BANKS.
HWVR FURTHER N...COLDER TEMPS EARLIER IN THE PERIOD HAVE SLOWED
SNOW MELT...WILL GIVE WAY TO 40S SUN WITH 2-3 INCHES OF QPF..AND
MAYBE AN INCH OF SNOW MELT.
AT THIS POINT WILL ISSUE A FLOOD WATCH FOR SAT NT THROUGH
SUN...WITH 2-3 IN QPF N TIER...AN INCH OF SNOW MELT. POTENTIAL FOR
WIDESPREAD MINOR FLOODING INCRG.
BY SUN NT SFC LOW EXISTS NY INTO N NEW ENG AND DRY SLOT MOVES INTO
RGN. RN SHOULD DIM TO SCT -SHRA BUT TEMPS WILL REMAIN ABV FREEZING
ACROSS MOST AREA...AND SNOW MELT AND RUNOFF WILL CONTINUE.
DURING SUNDAY AND SUN NT TEMPS ARE EITHER NON DIURNAL OR MAV/MET
MAX MIN VALUES ARE 24 HR VALUES FM SAT. WILL USE 3 HRLY TEMPS IN
GRIDS.
MONDAY THE SFC LOW AND ITS CDFNT MOVE EAST OF RGN. FCA WILL BE IN
DRY SLOT WITH VERY GRADUAL CAA. HWVR AT 500HPA MAJOR TROF IS BEING
CARVED OUT OVER GRTLKS AS SERIES OF SHORT WVS DIG S INTO IT. THIS
KEEPS A SW 500HPA FLOW OVR RGN...RESULTING IN A GRADUAL EXIT OF
FRONTAL SYSTEM AND GRADUAL COOL DOWN MONDAY. GFS/ECM PUSH SOME
PCPN INTO INTO FAR SE CORNER OF FCA MON. THIS IS MUCH LESS
PRONOUNCED THAN PVS RUNS...AND REALLY ONLY JUSTIFIES MAINTAINING
CHC POPS AT THIS TIME. DURING MON AND TUE CAA AND INCRG WIND
GRADIENT WILL BE THE RULE AS TEMPS RETURN TO NR OR BLO NORMAL
TUES WITH PASSAGE OF 500HPA TROF THROUGH RGN MONDAY NT AND TUES.
ITS FOLLOWED BY A MUCH STRONGER CDFNT AND BRISK N-NE WINDS IN ITS
WAKE.
CDFNT PASSAGE WILL TRIGGER SCT -SHSN MON NT...BUT H850 AND LLVL FLOW
NOT FAVORABLE FOR LK RESPONSE IN FCA TUE. TUES TEMPS WILL BE SVRL
DEG BLO NORMAL AS SFC HIGH BEGINS BUILDING SE FM OTTAWA VLY.
500HPA TROF MAY STILL BE SUF TO TRIGGER SCT INSTAB -SHSN TUES AND
TUE NT. SKIES WILL BE PC WITH MORE CLOUDS N AND FEWER S MON-TUE.
CHRISTMAS DAY WILL START ON THE FRIGID SIDE AS CLR SKIES...LARGE
SFC HIGH OVER RGN AND SOME OF THE LONGEST NIGHTS OF THE YEAR WILL
ALLOW IDEAL RADIATIONAL COOLING. MEX LOWS AT SLK ARE -19F TO +10
AT POU.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
CHRISTMAS DAY 500HPA AND SFC RIDGE WILL CREST OVR RGN RESULTING IN
FAIR RATHER COLD DAY. AFTER FRIGID START TEMPS WILL REBOUND TO THE
TEENS AND LOW 20S. BY EVENING THE FLOW REGIME FOR THE REST OF THE
WEEK WILL BE SETTING UP WITH FAST W-NW FLOW ACROSS RGN. CLIPPER
TYPE TROF IN GFS (ECMWF CUTS IT OFF) RACES THROUGH UPR GRTLKS WED
NT INTO QB THU LEAVING AREA IN SLIGHTLY MILDER AIR MASS. SOME
MODELS SUG SOME -SHSN WITH IT...BUT MINOR AMOUNTS OR FLURRIES. WEEK
ENDS WITH GFS PUSHING A CDFNT INTO RGN AND BECOMING AN ANNA TYPE
FRONT WITH A PERIOD OF -SN SUGGESTED FRI FOLLOWED BY STRONG CAA
AND SOME LK EFFECT SAT. THE ECMWF CUTS OFF THE 500HPA LOW THU AND
BRINGS THIS FRONT QUICKLY THROUGH WITH THE CLIPPER THU. AS THIS
IS MAINLY A BLO NORMAL TEMP PERIOD WITH RATHER NON DESCRIPT WX
TIED TO FAST MOVING SYSTEMS WILL POPULATE REMAINDER OF EFP WITH
HPC MID SHIFT GRIDS.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
FLYING CONDITIONS ARE CURRENTLY HIGH END MVFR TO VFR ACROSS THE
REGION WITH INCREASING AMOUNTS OF CLOUDINESS. REGIONAL MOSAIC
RADAR SHOWS RAIN SHOWERS APPROACHING FROM CENTRAL NY FOR LATER
THIS MORNING. THIS WILL ALLOW FOR WIDESPREAD MVFR CONDITIONS...AND
POSSIBLY PERIODS OF IFR FOR THE MID TO LATE MORNING HOURS INTO THE
EARLY AFTN DUE TO RAIN...MIST AND LOW STRATUS CLOUDS. IT MAY TAKE
UNTIL LATE IN THE DAY FOR THE RAIN TO REACH KPOU...WHEN A MORE
STEADIER AND HEAVIER RAINFALL ARRIVES. THIS RAIN WILL CONTINUE
THROUGH TONIGHT WITH WIDESPREAD IFR CONDITIONS.
LLWS WILL BE IN PLACE THROUGH EARLY THIS AFTN WITH 2 KFT WINDS AROUND
35-40 KTS OUT OF THE WEST-SOUTHWEST. MEANWHILE...SFC WINDS WILL BE
MAINLY LIGHT...BECOMING SOUTHERLY AT 10 KTS OR LESS. LLWS SHOULD
END BY THIS AFTN AS THE BEST LOW LEVEL JET SHIFTS AWAY FROM THE
AREA. SFC WINDS WILL REMAIN LIGHT RIGHT INTO TONIGHT.
OUTLOOK...
SUNDAY: HIGH OPERATIONAL IMPACT. RA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
MONDAY NIGHT-TUESDAY NIGHT: LOW OPERATIONAL IMPACT. BREEZY.
SLIGHT CHANCE OF SHSN.
CHRISTMAS DAY-WED NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE
WEEKEND WITH INCREASING SNOW MELT. MEANWHILE A SERIES OF LOW
PRESSURE SYSTEMS WILL BE PROPAGATING ALONG A NEARLY STATIONARY
FRONT FROM THE NIAGARA FRONTIER TO VERMONT WITH 2-3 INCHES OF RAIN
EXPECTED IN THE ADIRONDACKS...BUT LESSER AMOUNTS SOUTH.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S IN MOST
AREAS...MID 40S FAR NORTH AND 60S SOUTH OF ALBANY.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL SNOW WILL MELT. IN THE SOUTH THIS WILL BE
SUFFICIENT FOR SIGNIFICANT WITHIN BANK RISES...BUT FLOODING IS NOT
EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 2 TO 3 INCHES OF RAIN AND UP TO
AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED. FLOOD
WATCHES HAVE BEEN ISSUED FOR TONIGHT THROUGH SUNDAY NIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FLOOD WATCH FROM THIS EVENING THROUGH MONDAY MORNING FOR
NYZ032-033-038>040-042-043-082.
FREEZING RAIN ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
SUNDAY FOR NYZ042-043.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...FRUGIS
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...FRUGIS
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
851 AM EST SAT DEC 21 2013
.SYNOPSIS...
HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY
MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD
FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY.
COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON
THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING HAS HELPED
CAUSE AREAS OF STRATUS AND FOG THIS MORNING. HEATING AND MIXING
LATER THIS MORNING SHOULD HELP DIMINISH THE LOW CLOUDINESS... BUT
SOME CLOUDINESS SHOULD LINGER THROUGH THE DAY BECAUSE OF
ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL MOISTURE STREAMING INTO
THE AREA IN THE SOUTHWEST FLOW. GENERALLY EXPECT PARTLY CLOUDY OR
MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK AND MOISTURE SHALLOW
WITH FORCING ASSOCIATED WITH THE FRONT WELL TO THE WEST. THE
SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION MODELS KEEP THE
FORECAST AREA DRY. IT WILL BE WARM AND THE TEMPERATURE GUIDANCE
WAS CONSISTENT DISPLAYING HIGHS IN THE MIDDLE AND UPPER 70S WHICH
WILL BE 15 TO 20 DEGREES ABOVE NORMAL. THE BUFKIT MOMENTUM
TRANSFER TOOL AND HRRR INDICATED WIND GUSTS NEAR 20 KNOTS THIS
AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE
OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP
ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS
MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE GUIDANCE
BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL BE 20 TO
30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM RECORDS FOR THE
DATE WILL BE IN JEOPARDY.
SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT
NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES
SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW
PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF
SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION
OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40
TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY
WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE
FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY
IN THE WEST PART OF THE FORECAST AREA SUNDAY.
A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL
RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING
TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG
UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN
THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH
THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF
HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT.
THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER
FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE
UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE
VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND
EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL
SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED
TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN
WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL
FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY
BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND
THE FRONT LATER IN THE DAY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS
EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES
FOR RAIN BY THE END OF THE WEEK.
THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY
ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH
PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN
STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH
TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS
TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD
MAXIMUM TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S
WHILE LOW TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL
WEDNESDAY MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING.
DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY
THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF
A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL
INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND
ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS
THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN
POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE
WEEK SHOULD BE NEAR NORMAL.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS FOR MUCH OF THE PERIOD...GIVING WAY TO MVFR/IFR
CONDITIONS AFTER 22/02Z.
PATCHY FOG DEVELOPED OVERNIGHT...HOWEVER WITH THICKENING MID AND
UPPER LEVEL CLOUDS MIGRATING INTO THE AREA THE FOG HAS LESSENED OVER
THE PAST COUPLE OF HOURS. EXPECT VFR CONDITIONS RETURNING TO ALL TAF
SITES BY 15Z. MOISTURE WILL CONTINUE TO INCREASE THROUGH THE
AFTERNOON HOURS WITH CLOUDS CONTINUING TO THICKEN AND LOWER. BY
22/02Z EXPECT CIGS TO BEGIN RAPIDLY LOWERING WITH MVFR EXPECTED WITH
FURTHER LOWERING TO IFR BETWEEN 22/06 AND 22/08Z. WINDS WILL BE
SOUTHERLY AROUND 8 KNOTS THROUGH THE PERIOD.
EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS
EXPECTED INTO EARLY SUNDAY MORNING. A COLD FRONT WILL CROSS THE
REGION LATE SUNDAY INTO MONDAY BRINGING SHOWERS...POSSIBLY
THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS.
&&
.CLIMATE...
COLUMBIA
RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918
RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011
AUGUSTA BUSH
RECORD HIGH TODAY 12/21/13...79 SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898
RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
649 AM EST SAT DEC 21 2013
.SYNOPSIS...
HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY
MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD
FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY.
COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON
THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING HAS HELPED
CAUSE AREAS OF STRATUS AND FOG EARLY THIS MORNING. HEATING AND
MIXING LATER THIS MORNING SHOULD HELP DIMINISH THE LOW CLOUDINESS...
BUT SOME CLOUDINESS SHOULD LINGER THROUGH THE DAY BECAUSE OF
ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL MOISTURE STREAMING INTO
THE AREA IN THE SOUTHWEST FLOW. GENERALLY EXPECT PARTLY CLOUDY OR
MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK AND MOISTURE SHALLOW
WITH FORCING ASSOCIATED WITH THE FRONT WELL TO THE WEST. THE
SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION MODELS KEEP THE
FORECAST AREA DRY. THE NAM...GFS AND ECMWF MOS INDICATE POPS OF 20
PERCENT OR LESS. IT WILL BE WARM AND THE TEMPERATURE GUIDANCE WAS
CONSISTENT DISPLAYING HIGHS IN THE MIDDLE AND UPPER 70S WHICH WILL
BE 15 TO 20 DEGREES ABOVE NORMAL. THE BUFKIT MOMENTUM TRANSFER
TOOL AND HRRR INDICATED WIND GUSTS NEAR 20 KNOTS THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE
OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP
ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS
MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE GUIDANCE
BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL BE 20 TO
30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM RECORDS FOR THE
DATE WILL BE IN JEOPARDY.
SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT
NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES
SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW
PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF
SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION
OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40
TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY
WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE
FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY
IN THE WEST PART OF THE FORECAST AREA SUNDAY.
A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL
RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING
TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG
UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN
THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH
THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF
HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT.
THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER
FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE
UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE
VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND
EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL
SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED
TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN
WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL
FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY
BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND
THE FRONT LATER IN THE DAY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS
EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES
FOR RAIN BY THE END OF THE WEEK.
THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY
ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH
PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN
STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH
TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS
TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD
MAXIMUM TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S
WHILE LOW TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL
WEDNESDAY MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING.
DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY
THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF
A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL
INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND
ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS
THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN
POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE
WEEK SHOULD BE NEAR NORMAL.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS FOR MUCH OF THE PERIOD...GIVING WAY TO MVFR/IFR
CONDITIONS AFTER 22/02Z.
PATCHY FOG DEVELOPED OVERNIGHT...HOWEVER WITH THICKENING MID AND
UPPER LEVEL CLOUDS MIGRATING INTO THE AREA THE FOG HAS LESSENED
OVER THE PAST COUPLE OF HOURS. EXPECT REMAINING FOG TO DISSIPATE
WITH SUNRISE AND ALL SITES RETURNING TO VFR BY 13Z. MOISTURE WILL
CONTINUE TO INCREASE THROUGH THE AFTERNOON HOURS WITH CLOUDS
CONTINUING TO THICKEN AND LOWER. BY 22/02Z EXPECT CIGS TO BEGIN
RAPIDLY LOWERING WITH MVFR EXPECTED WITH FURTHER LOWERING TO IFR
BETWEEN 22/06 AND 22/08Z. WINDS WILL BE SOUTHERLY AROUND 8 KNOTS
THROUGH THE PERIOD.
EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS
EXPECTED INTO EARLY SUNDAY MORNING. A COLD FRONT WILL CROSS THE
REGION LATE SUNDAY INTO MONDAY BRINGING SHOWERS...POSSIBLY
THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS.
&&
.CLIMATE...
COLUMBIA
RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918
RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011
AUGUSTA BUSH
RECORD HIGH TODAY 12/21/13...79 SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898
RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
600 AM EST SAT DEC 21 2013
.SYNOPSIS...
HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY
MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD
FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY.
COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON
THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING HAS HELPED
CAUSE AREAS OF STRATUS AND FOG EARLY THIS MORNING. HEATING AND
MIXING LATER THIS MORNING SHOULD HELP DIMINISH THE LOW CLOUDINESS...
BUT SOME CLOUDINESS SHOULD LINGER THROUGH THE DAY BECAUSE OF
ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL MOISTURE STREAMING INTO
THE AREA IN THE SOUTHWEST FLOW. GENERALLY EXPECT PARTLY CLOUDY OR
MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK AND MOISTURE SHALLOW
WITH FORCING ASSOCIATED WITH THE FRONT WELL TO THE WEST. THE
SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION MODELS KEEP THE
FORECAST AREA DRY. THE NAM...GFS AND ECMWF MOS INDICATE POPS OF 20
PERCENT OR LESS. IT WILL BE WARM AND THE TEMPERATURE GUIDANCE WAS
CONSISTENT DISPLAYING HIGHS IN THE MIDDLE AND UPPER 70S WHICH WILL
BE 15 TO 20 DEGREES ABOVE NORMAL. THE BUFKIT MOMENTUM TRANSFER
TOOL AND HRRR INDICATED WIND GUSTS NEAR 20 KNOTS THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE
OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP
ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS
MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE GUIDANCE
BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL BE 20 TO
30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM RECORDS FOR THE
DATE WILL BE IN JEOPARDY.
SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT
NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES
SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW
PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF
SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION
OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40
TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY
WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE
FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY
IN THE WEST PART OF THE FORECAST AREA SUNDAY.
A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL
RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING
TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG
UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN
THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH
THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF
HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT.
THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER
FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE
UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE
VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND
EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL
SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED
TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN
WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL
FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY
BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND
THE FRONT LATER IN THE DAY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS
EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES
FOR RAIN BY THE END OF THE WEEK.
THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY
ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH
PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN
STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH
TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS
TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD MAXIMUM
TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S WHILE LOW
TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL WEDNESDAY
MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING.
DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY
THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF
A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL
INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND
ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS
THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN
POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE
WEEK SHOULD BE NEAR NORMAL.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
LOW CONFIDENCE REGARDING CIG/VSBY RESTRICTIONS EARLY THIS MORNING.
CLOUDS CONTINUE TO INCREASE FROM THE WEST AS WITH PATCHY FOG
BEGINNING TO FORM. LOW AND MID CLOUDS HAVE MOVED INTO EASTERN GA
WHICH WILL WORK TO LESSEN FOG POTENTIAL...HOWEVER WITH FOG
ALREADY DEVELOPING POTENTIAL FOR FOG REMAINS MODERATE AND THUS
CONFIDENCE REMAINS LOW DUE TO TIMING ISSUES. HAVE REMAINED WITH
MVFR FOG FOR CAE/CUB/DNL WITH IFR/LIFR FOR AGS/OGB. FOG WILL ERODE
AFTER SUNRISE AND ONSET OF MIXING WITH REMAINDER OF THE PERIOD
VFR. WINDS WILL BE LIGHT AND VARIABLE THROUGH MID MORNING THEN
BECOME SOUTHWESTERLY AROUND 10 KNOTS THROUGH THE END OF THE
PERIOD.
EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS
EXPECTED LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING. A COLD
FRONT WILL CROSS THE REGION LATE SUNDAY INTO MONDAY BRINGING
SHOWERS...POSSIBLY THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS.
&&
.CLIMATE...
COLUMBIA
RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918
RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011
AUGUSTA BUSH
RECORD HIGH TODAY 12/21/13...79 SET IN 1998
RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898
RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
507 AM CST Sat Dec 21 2013
...Updated aviation discussion...
.SHORT TERM...(This evening through Saturday)
ISSUED AT 355 AM CST SAT DEC 21 2013
A strong shortwave trough centered west of El Paso early this
morning will eject northeastward across the southern plains through
this evening. Plenty of low level moisture was being ejected into
this system from the south. The deformation/trowal will set up
across southwestern Kansas later today and the 06z NAM and 00 UTC
ECMWF seem to have the best handle on the distribution and amounts
of snow. Given that this is a fast moving system, snow totals of 2
to 5 inches are generally expected in the advisory area along and
southeast of a line from Elkhart to Garden City to Ness City to
LaCrosse, with the highest amounts from Meade eastward into Barber
and Pratt counties. A few locations could reach 6 inches. The snow
may start off as sleet or freezing rain in south central Kansas
later this morning since RAP soundings show an elevated warm layer
around 1C through 18Z. Temperatures may rise into the upper 20s and
lower 30s before the snow arrives, and then fall back into the mid
20s. Afternoon temperatures will be warmer in places like Syracuse,
Scott City and Dighton where not much in the way of snow is
expected. Temperatures tonight will be held up by 10kt north winds
and cloud cover; but with fairly chilly air pushing southward out of
the northern plains in the wake of the storm system, temperatures
should drop into the teens.
.LONG TERM...(Sunday through Friday)
ISSUED AT 246 AM CST SAT DEC 21 2013
Models this morning were in fairly good agreement with lifting a
weakening upper level trough across the Mid Mississippi Valley on
Sunday. At the same time a northern branch upper level trough will
move out of the Rockies and across the Central Plains as an area
of high pressure at the surface builds into western Kansas.
Although no measurable precipitation is expected with this next
system, there will be some increasing clouds late Sunday into
Sunday night. This increasing cloud cover will limit how cold
temperatures will fall Sunday night, however give light winds and
fresh snow cover across western Kansas will still undercut the
coolest guidance for overnight lows. Temperatures falling back
into the single digits still looks reasonable. Lows near zero no
out of the question near the Oklahoma border if skies remain clear
for several hours after midnight.
Westerly downslope flow will improve early next week which will
allow temperatures to gradually warm. Snow cover will limit how
much warming will occur Monday and Tuesday, but at this time the
latest CRExtendFcst_Init still looks reasonable. Where the heavier
snowfall is expected later today the afternoon temperatures are
expected to warm into the upper 30s by Tuesday afternoon.
Elsewhere highs in the mid to upper 40s still appear likely given
the 850mb temperature trends from the GFS and ECMWF. This slow
warming trend will briefly end mid week as a cold front drops
south across Kansas Tuesday night Wednesday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 505 AM CST SAT DEC 21 2013
Clouds will thicken and lower today with low VFR cigs expected to
develop after 15z at DDC and GCK. MVFR cigs are then expected to
develop by 21z. With the lowering cigs some light snow is also
expected to develop with a period of steady light snow appearing
most likely between 21z and 03z. At HYS cigs will also be lowering
through the day, however based on the 06z NAM BUFR soundings VFR
cigs are expected today and early tonight. North winds will
continue at 10 knots or less at all three taf sites.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 30 18 28 4 / 90 90 0 0
GCK 31 18 29 9 / 50 30 0 0
EHA 28 18 32 17 / 90 20 0 0
LBL 28 18 29 11 / 100 40 0 0
HYS 32 16 28 10 / 40 60 10 20
P28 29 19 27 3 / 100 90 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Midnight CST tonight FOR KSZ046-
063>066-075>081-084>090.
&&
$$
SHORT TERM...Finch
LONG TERM...Burgert
AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1028 AM EST SAT DEC 21 2013
.SYNOPSIS...
ISSUED AT 457 AM EST SAT DEC 21 2013
QUIET WEATHER IS EXPECTED DURING THE DAY TODAY BEFORE ANOTHER STORM
SYSTEM AFFECTS THE REGION TONIGHT INTO SUNDAY. THIS EVOLVING SYSTEM
WILL LIFT INTO THE NORTHERN OHIO VALLEY SATURDAY NIGHT...BRINGING
LIGHT TO MODERATE AMOUNTS OF SNOW TO THE REGION. COLD AIR WILL
FILTER BACK INTO THE GREAT LAKES MONDAY AND TUESDAY...GENERATING
SOME LAKE EFFECT SNOW...ACROSS PARTS OF NORTHERN MICHIGAN TO BEGIN
THE UPCOMING WORK WEEK. A COUPLE OF ALBERTA CLIPPERS WILL THEN
LIKELY BRINGING SOME LIGHT SNOW FOR CHRISTMAS DAY AND A CHANCE FOR
LIGHT SNOW ON THURSDAY.
&&
.UPDATE...
ISSUED AT 1028 AM EST SAT DEC 21 2013
NO MAJOR CHANGES TO THE FORECAST AT THIS HOUR...AND AN OVERALL
QUIET...ALBEIT CLOUDY DAY ON TAP FOR THE NORTH WOODS. 12Z APX
REVEALING A FAIRLY DEEP SATURATED LOW LAYER UP TO NEARLY 750
MB...ALTHOUGH THE TEMP/DEWPOINT SPREAD DOES OPEN A BIT IN LAYERS.
NONETHELESS...HAVE HAVE A FEW REPORTS OF -FZDZ AROUND THE TVC AREA
AND OBS AROUND THE GRAND TRAVERSE BAY AREA DOES HINT AT PATCHY
FZDZ VIA REDUCED VSBYS AND LOW CIGS. EVEN GLR REPORTING LOW VSBY
AND FZFG. SO...HAVE ADDED PATCHY -FZDZ TO THE FORECAST THROUGH THE
MORNING AND EVEN ISSUED AN SPS TO COVER SOME POTENTIAL SLICK
SPOTS/BLACK ICE THIS MORNING. RUC FORECAST SOUNDINGS SHOW ONGOING
LOW LEVEL DRYING/OPENING THE SOUNDINGS JUST A BIT THROUGH THE
AFTERNOON...SUGGESTING -FZDZ WILL END. WILL SEE.
OTHERWISE...JUST INGESTING OBSERVATIONAL TRENDS AND INCOMING 12Z
GUIDANCE TO SEE WHAT...IF ANY ADJUSTMENTS MAY BE NEEDED TO THE
UPCOMING EVENT LATER TONIGHT THROUGH SUNDAY. NO BIG SURPRISES SO
FAR.
UPDATE ISSUED AT 628 AM EST SAT DEC 21 2013
UPDATED SKY GRIDS. WINDS ARE TURNING LIGHT OUT OF THE NORTH WITH
LITTLE TO NO SPEEDS REMAINING 5 KTS OR LESS. SLOWED ANY SORT OF
GOOD LOW LEVEL DRYING AND AM KEEPING LOW CLOUDS AROUND THROUGH A
GOOD PORTION OF THE DAY...PLUS A PLETHORA OF MID AND HIGH LEVEL
CLOUDS REMAINS OVER MUCH OF THE REGION AND DO NOT SEE MUCH
HAPPENING WITH THAT TODAY. THUS...CLOUDY FOR MOST OF THE
DAY...THIS IS ESPECIALLY TRUE ACROSS THE SE CWA WHERE LOW LEVEL
MOISTURE WILL BE RICH/THICK ENOUGH FOR CLOUDS. NO PRECIPITATION
EXPECTED FOR THE DAY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 457 AM EST SAT DEC 21 2013
CURRENTLY...SPLIT FLOW IN THE UPPER LEVELS WITH A NRN STREAM JET
STREAK OVERHEAD...AND A SRN STREAM JET STREAK LIFTING INTO OK WHICH
IS EJECTED FROM A CUT OFF LOW OVER FAR WEST TX. IN THE NRN
STREAM...WE HAVE ONE WEAK AND SHEARED OUT VORT MAX RUNNING INTO
EASTERN LAKE SUPERIOR...WHICH HAS CONTINUED TO PRODUCE LIGHT
SNOW/FLURRY RETURNS ON MQT RADAR WHICH WERE WORKING UP THROUGH
WESTERN SECTIONS OF CHIP/MACK COUNTIES OF EASTERN UPPER. H8 LLJ
FORCING IS COMPLETELY DONE AS WIND DIRECTIONS HAVE VEERED WEST...AND
ACTUALLY DRYING WAS UNDERWAY FROM NORTH TO SOUTH. THIS ALSO HELPING
TO KEEP ANY LIGHT SNOW AT BAY ACROSS EASTERN UPPER. PECULIAR EARLIER
WEAK RADAR RETURNS EMANATING FROM ANTRIM INTO CRAWFORD COUNTY HAS
BEEN A VERY FINE LIGHT SNOW...AND THIS WAS ALSO ERODING...LIKELY DUE
TO THE NOW H8 DRYING. TOTAL MOISTURE IN THE COLUMN IS DRYING...AND
WILL NOW BE SLOWLY ERODING ANY CHANCE OF PRECIP AND PATCHY FREEZING
DRIZZLE...THE LATTER OF WHICH SEEMS TO BE ISOLATED AT BEST...WITH
ONLY CADILLAC OBSERVATION SUGGESTING THE POSSIBILITY OF FREEZING
DRIZZLE...AND ACTUALLY BELIEVE THAT IS MORE OF A LOWERING
CEILING/FREEZING FOG TYPE THING. DO NOT BELIEVE THAT THIS IS ANY
SERIOUS IMPACT.
TODAY AND TONIGHT...WEAK/SHEARED OUT VORT MAX WILL EXIT EAST OVER
THE NEXT COUPLE OF HOURS WITH H8 DRYING CONTINUING TO SLIDE
SOUTH...ENDING ALL LIGHT SNOW IN EASTERN UPPER. WINDS DO VEER MORE
NORTHERLY INTO THE DAYLIGHT HOURS...AND LOW LEVEL TEMPS RESULT IN
DELTA T`S SUFFICIENT ENOUGH FOR MAYBE A FEW FLURRIES ACROSS FAR NE
LOWER. OUTSIDE OF THAT...A QUIET PERIOD OF WEATHER FOR THE
DAY...WITH DEEP SW FLOW ALOFT...ABOVE THE SHALLOW COLDER AIR. THIS
WILL CONTINUE TO BRING IN MIDDLE AND UPPER LEVEL CLOUDS. DO NOT SEE
THE NORTHERLY FLOW BEING STRONG ENOUGH TO SCOUR OUT THE LOW LEVEL
CLOUDS ACROSS THE SE PART OF THE CWA. THIS WILL RESULT IN A RETURN A
DEEPLY SATURATED ATMOSPHERE IN THE AFTERNOON. WE WILL SEE SOME WEAK
ENERGY EJECTED FROM THE SRN STREAM CUT OFF WORKING IN OVER THE FAR
SE CWA LATE IN THE AFTERNOON FOR THE FIRST CHANCES FOR SEEING SOME
LIGHT SNOW FALL. STRONGER ENERGY/MODERATE DEEP LAYER -DIVQ ARRIVES
OVERNIGHT...AS THE ATMOSPHERE DEEPENS IN MOISTURE. THIS WILL MAINLY
BE ACROSS NRN LOWER. THE DEEP MOISTURE IS BROUGHT IN BY A WIDE OPEN
GULF (CURRENTLY STREAMING DEEP LOW LEVEL MOISTURE INTO THE OHIO
RIVER VALLEY) ARRIVES VIA STRONG LOW LEVEL JET. AS THE SRN STREAM
CUT OFF OPENS UP AND LIFTS INTO ILLINOIS LATE TONIGHT/DAYBREAK
TOMORROW...THE SFC LOW DEEPENS SOME...AND WINDS BACK...ALLOWING THE
BEST LOW LEVEL MOISTURE TURN GET LIFTED FURTHER NORTH INTO OUR NECK
OF THE WOODS. AT THE SAME TIME...STRONG DEEP LAYER -DIVQ IS SETTLED
IN ON US...AND SNOWS WILL PICK UP IN INTENSITY. CAN SEE AROUND A
COUPLE OF INCHES BY DAYBREAK ACROSS THE SE CWA...LESSENED NEAREST
THE SAG BAY BY LOW LIQUID-SNOW RATIOS AND THE POSSIBILITY (IF WARMER
NAM IS RIGHT) OF A MIX WITH SLEET.
FOR A DISCUSSION ON THE WATCH SITUATION...SEE BELOW.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 457 AM EST SAT DEC 21 2013
AN ACTIVE WEATHER PATTERN ALONG WITH COLD TEMPERATURES CONTINUE
THROUGH THE FORECAST PERIOD WITH A MEAN TROUGH REMAINING IN PLACE
ACROSS CENTRAL CANADA INTO THE GREAT LAKES REGION. IN
ADDITION...UPPER LEVEL DISTURBANCES MOVING THROUGH THE FLOW ALOFT
WILL BRING NUMEROUS CHANCES FOR SNOW SHOWERS...ENHANCED FROM TIME TO
TIME BY THE BIG LAKES. MEANWHILE...THE WELL ADVERTISED SOUTHERN JET
STREAM SYSTEM COULD STILL POTENTIALLY BRING WHAT LOOKS LIKE A
MODERATE AMOUNT OF SNOW TO REGION LATER SATURDAY NIGHT INTO SUNDAY.
THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND SNOW AMOUNTS FOR
SATURDAY NIGHT INTO SUNDAY THEN THE USUAL SUSPECTS...POPS AND
TEMPERATURES FOR THE REMAINDER OF THE FORECAST.
SUNDAY...SOUTHERN BRANCH ENERGY MOVES NORTHWARD ALONG A TIGHTENING
BAROCLINIC ZONE. LATEST MODEL RUNS CONTINUE TO HAVE A MODEST AREA OF
LOW PRESSURE AT THE SURFACE TRACKING ACROSS EITHER NORTHERN OHIO
(MAJORITY OF MODELS) OR SOUTHWEST LOWER MICHIGAN (INCONSISTENT AND
CONTINUED OUTLIER NAM). THERE IS STILL THE POTENTIAL FOR LAKE
ENHANCEMENT OFF OF LAKE HURON ACROSS NORTHEAST LOWER AS A POCKET OF
COLDER AIR (850 MB TEMPS -10 TO -12 C) TRIES TO SYNC UP WITH THE
TAIL END OF DEEP SYNOPTIC MOISTURE. OVERALL...A GENERAL LIGHT TO
MODERATE SNOWFALL IS STILL EXPECTED WITH STORM TOTAL AMOUNTS OF
BETWEEN 4 AND 8 INCHES OF GREASY SNOW WHICH WILL BE COVERED WITH A
WINTER WEATHER ADVISORY FOR ALL COUNTIES OF NORTHERN LOWER MICHIGAN.
WILL STILL HAVE TO BE COGNIZANT OF POSSIBLE SNEAKY LAKE ENHANCEMENT
ADDING TO THE TOTALS ACROSS NORTHEAST LOWER. MEANWHILE...ACROSS
EASTERN UPPER...2 TO 3 INCHES OF ACCUMULATION IS EXPECTED. HIGHS
RANGING FROM THE UPPER TEENS TO MIDDLE 20S...BUT LIKELY FALLING OFF
IN THE AFTERNOON AS COLD AIR ADVECTION KICKS IN.
SUNDAY NIGHT...WRAP AROUND MOISTURE/DEFORMATION ZONE AXIS SITS OVER
THE REGION. THIS WILL LIKELY BRING SOME LIGHT SNOW...WITH ADDITIONAL
ACCUMULATIONS OF ONE TO PERHAPS TWO INCHES. LOWS RANGING FROM THE
COLDER SINGLE DIGITS ABOVE ZERO TO THE MIDDLE TEENS.
MONDAY AND MONDAY NIGHT...A NORTHERN STREAM TROUGH ALONG WITH
ANOTHER SHOT OF ARCTIC AIR (850 MB TEMPS DOWN TO -20 C OR SO) DROPS
DOWN INTO THE REGION BRINGING ADDITIONAL CHANCES FOR MAINLY LIGHT
SNOW. THE FLOW IS RATHER LIGHT OVERALL BUT MAY STILL BE JUST STRONG
ENOUGH TO PRODUCE SOME LAKE EFFECT (GENERALLY OUT OF THE NORTH
NORTHWEST). HOWEVER...AM NOT EXPECTING BIG TIME ACCUMULATIONS WITH
MODEL SOUNDINGS SHOWING INVERSION HEIGHTS OF ONLY AROUND 3000 FEET
OR SO PLUS SNOWFLAKE SIZES WILL LIKELY BE RATHER SMALL. HIGHS MAINLY
IN THE TEENS. LOWS RANGING FROM THE COLDER SINGLE DIGITS TO THE
MIDDLE TEENS.
TUESDAY...PERHAPS SOME LINGERING NORTH NORTHWEST FLOW LAKE EFFECT IN
THE MORNING. OTHERWISE...ARCTIC HIGH PRESSURE PRESSES DOWN FROM THE
NORTH YIELDING VERY COLD TEMPERATURES AND PERHAPS CLEARING SKIES (IF
WE CAN SCOUR OUT THE LIKELY STUBBORN STRATUS). HIGHS ONLY EXPECTED
TO RANGE FROM THE UPPER SINGLE DIGITS (ABOVE ZERO) TO THE MIDDLE
TEENS. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO AT NIGHT.
WEDNESDAY THROUGH FRIDAY...A PARADE OF SHORT WAVES DROP DOWN THROUGH
THE FLOW. EXTENDED MODELS CONTINUE TO VARY ON THE EXACT TIMING AND
DETAILS SO WILL NOT GET TOO FANCY...AND HAVE GENERAL CHANCES FOR
SNOW SHOWERS. THERE COULD BE SOME LAKE ENHANCEMENT AS WELL FROM TIME
TO TIME...BUT PINNING DOWN THE EXACT FLOW REGIMES IS NEARLY
IMPOSSIBLE THIS FAR OUT. HIGHS IN THE MIDDLE TO UPPER 20S WEDNESDAY
THEN COOLING OFF AGAIN INTO THE UPPER TEENS TO MIDDLE 20S FOR
THURSDAY AND THE MIDDLE TEENS TO AROUND 20 FOR FRIDAY. LOWS IN THE
TEENS WEDNESDAY NIGHT THEN THE SINGLE DIGITS FOR THURSDAY AND FRIDAY
NIGHTS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 628 AM EST SAT DEC 21 2013
A VERY WEAK NORTHERLY LOW LEVEL FLOW WILL DEVELOP THIS MORNING
WITH WEAKER THAN ANTICIPATED DRY AIR ADVECTION. THIS WILL KEEP
IFR/MVFR CIGS IN FOR THE MOST OF THE DAY...IF NOT ALL OF THE DAY
FOR MBL AND POSSIBLY APN/TVC. CAN STILL SEE PLN GOING VFR FOR A
PERIOD TODAY. WINDS VEER BACK TO OUT OF AN EASTERLY DIRECTION
THROUGH TONIGHT AND INCREASE IN SPEED IN ADVANCE OF DEEPENING LOW
PRESSURE THAT WILL WORK INTO THE MID MISSISSIPPI VALLEY BY
DAYBREAK. THICKER AND THICKER MID AND UPPER LEVEL SATURATION WILL
WORK ITS WAY BACK DOWN TO IFR CIGS OVERNIGHT WITH SNOWS DEVELOPING
BY DAYBREAK FOR ALL AIRPORTS EXCEPT MAYBE PLN. CIGS WILL LIKELY
FALL BACK INTO IFR/MVFR EARLIER IN THE EVENING HOWEVER...DUE TO
COOLING OF THE BL. SNOWS WILL LIKELY TURN IFR FROM A VISIBILITY
STANDPOINT.
&&
.MARINE...
ISSUED AT 457 AM EST SAT DEC 21 2013
A LIGHT EASTERLY WINDS REGIME WILL BRIEFLY TURN NORTHERLY OVER MANY
OF THE NEARSHORE WATERS THIS MORNING...BEFORE RETURNING TO EASTERLY
AND INCREASING THROUGH TONIGHT. THIS DUE TO STRENGTHENING LOW
PRESSURE THAT WILL LIFT THROUGH DETROIT. A PERIOD OF ADVISORY LEVEL
WINDS WILL DEVELOP TONIGHT...BEFORE DYING BACK OFF SUNDAY NIGHT INTO
MONDAY WITH THE APPROACH OF HIGHER PRESSURE. THESE LIGHTER WINDS
CONTINUE INTO TUESDAY.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 1 AM TO 7 PM EST SUNDAY FOR
MIZ016>036-041-042.
LH...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY
FOR LHZ345>349.
LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY
FOR LMZ323-341-342-344>346.
LS...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY
FOR LSZ321-322.
&&
$$
UPDATE...BA
SYNOPSIS...AS
SHORT TERM...SD
LONG TERM...AS
AVIATION...SD
MARINE...SD
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
945 AM EST SAT DEC 21 2013
LATEST UPDATE...
UPDATE
DENSE FOG IS BECOMING AN INCREASING CONCERN THIS MORNING MAINLY
ALONG AND SOUTH OF AN EAST-WEST SURFACE BOUNDARY LOCATED JUST
NORTH OF I-94. THERE ARE MANY REPORTS OF VISIBILITY AT OR BELOW
1/4 MILE ALONG AND SOUTH OF THIS BOUNDARY. HRRR GUIDANCE PUSHES
THE BOUNDARY SOUTH OF THE FORECAST AREA BY THIS AFTERNOON WITH
INCREASING WINDS FROM THE NORTHEAST...SO EXPECT DENSE FOG TO BE
LESS OF A CONCERN BY AFTERNOON. WILL HIGHLIGHT THE ONGOING FOG
CONCERN IN AN UPCOMING WSW UPDATE.
RADAR SHOWS THAT PRECIPITATION HAS BEGUN TO OVERSPREAD THE AREA
SOUTHEAST OF A MARSHALL TO MASON LINE. WE ARE A LITTLE CONCERNED
ABOUT AIR TEMPERATURES STAYING SUFFICIENTLY COLD FOR ICE
ACCUMULATION IN THE WARNED AREA. TEMPERATURES AND DEWPOINTS ARE
VERY CLOSE TO FREEZING. A POSITIVE FOR FREEZING RAIN IS COLDER
AND SLIGHTLY DRIER AIR UPSTREAM TO THE NORTHEAST. ALSO SEVERAL
MESONET SITES IN THE AREA ARE REPORTED TEMPERATURES BELOW
FREEZING. CURRENT EXPECTATIONS ARE THAT ICE ACCUMULATION ON
SECONDARY ROADS AND EXPOSED ROAD SURFACES REMAIN A DEFINITE
CONCERN. WILL BE CLOSELY MONITORING TEMPERATURE TRENDS OVER THE
NEXT FEW HOURS.
.SYNOPSIS...
ISSUED AT 329 AM EST SAT DEC 21 2013
A STORM SYSTEM DEVELOPING TO OUR SOUTHWEST WILL BEGIN TO MOVE INTO
THE AREA FROM THE SOUTH TODAY AND CONTINUE TO IMPACT THE AREA
THROUGH THE DAY ON SUNDAY. THIS SYSTEM WILL BRING MAINLY SNOW TO THE
NORTHWEST PORTION OF THE AREA...FREEZING RAIN ACROSS SOUTH CENTRAL
AND SOUTHEAST LOWER MICHIGAN...WITH A WINTRY MIX IN BETWEEN.
COLDER AIR WILL THEN MOVE IN ACROSS THE AREA LATER ON SUNDAY AND
REMAIN IN PLACE MOST OF THE UPCOMING HOLIDAY WEEK. OCCASIONAL
CHANCES OF SNOW SHOWERS CAN BE EXPECTED WITH SOME ACCUMULATIONS
LIKELY...ESPECIALLY CLOSER TO THE LAKESHORE.
&&
.UPDATE...
ISSUED AT 924 AM EST SAT DEC 21 2013
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 329 AM EST SAT DEC 21 2013
THE MAIN FOCUS OF THE SHORT TERM IS THE STORM SYSTEM EXPECTED TO
IMPACT THE AREA BEGINNING TODAY AND LASTING THROUGH SUNDAY. WE HAVE
TRANSITIONED THE HEADLINES FROM THE WATCH...TO AN ICE STORM WARNING
ACROSS THE FAR SE CORNER OF THE CWFA. ADVISORIES HAVE BEEN ISSUED
FOR THE REMAINDER OF THE CWFA FOR SNOW ACROSS THE NORTH AND A WINTRY
MIX ACROSS THE MIDDLE SECTION OF THE CWFA. NO MAJOR CHANGES IN THE
FCST HAVE BEEN MADE AS THE CONSENSUS OF THE MODELS IS GENERALLY
CONSISTENT WITH THE PREVIOUS RUNS.
WE WILL NEED TO DEAL WITH SOME FOG ISSUES ACROSS THE SOUTH THIS
MORNING.
THE GREATEST IMPACT OF THE INCOMING STORM SYSTEM LOOKS TO BE THE
THREAT OF RELATIVELY SIGNIFICANT AMOUNTS OF FREEZING RAIN/ICING
EXPECTED ROUGHLY SE OF I-69 LATER TODAY AND INTO THE EARLY OVERNIGHT
HOURS TONIGHT. WE EXPECT RAIN AND OR FREEZING RAIN TO START PUSHING
UP INTO THE SRN COUNTIES TOWARD THE AFTERNOON TODAY. AREAS ALONG AND
SOUTH OF I-94 COULD START OUT BARELY ABOVE FREEZING AT THE ONSET OF
PCPN. WE EXPECT ALL PCPN DOWN ACROSS THE SE CORNER TO TRANSITION TO
FREEZING RAIN AS THE COLD AND SOMEWHAT DRIER NE FLOW WILL BRING
TEMPS DOWN DUE TO ADVECTION AND EVAPORATIVE COOLING.
QPF ACROSS THE SE COUNTIES LOOKS TO BE OVER AN INCH THROUGH THE
EARLY OVERNIGHT HOURS AS THEY BARELY GET UNDER THE NRN PERIPHERY OF
THE BEST MOISTURE AXIS WITH THIS SYSTEM. AN ABOVE FREEZING LAYER
ALOFT IS MAINTAINED MOST OF THE TIME AS THE SFC TEMPS DROP TO AROUND
OR JUST BELOW FREEZING. NOT ALL OF THIS QPF WILL GO INTO THE ICING
EXPECTED DUE TO LATENT HEAT AND RUNOFF PROCESSES. HOWEVER WITH THAT
MUCH QPF...EVEN A PORTION OF IT FREEZING WILL CREATE A GOOD COATING
OF ICE...UP AROUND HALF AN INCH WILL BE LIKELY.
THE TRANSITION IN P-TYPE WILL BE SOMEWHAT TRICKY ACROSS THE CENTRAL
PORTION OF THE CWFA NW OF I-69 TO ROUGHLY M-20. HOWEVER WE EXPECT
THAT FREEZING RAIN AND SLEET TO BE MORE PREVAILING WITH SOME SNOW
POSSIBLE. A SLIGHT ABOVE FREEZING LAYER WILL BE PRESENT WITH THE
LAYER THINNER AND COOLER AS YOU MOVE NW. QPF AMOUNTS WILL BE QUITE A
BIT LESS AS THE MOISTURE AXIS REMAINS SE OF THIS AREA. IT WILL BE
TOUGH TO GET HIGH IMPACT FREEZING RAIN AMOUNTS IN THIS AREA. HOWEVER
ONE THING TO CONSIDER IS THE GLAZE IN PLACE ALREADY FROM THE THU
NIGHT/FRI EVENT.
THE PCPN IN BOTH OF THESE AREAS IS EXPECTED TO LIGHTEN UP
SIGNIFICANTLY BETWEEN 06-12Z SUN AS THE DRY SLOT IS EXPECTED TO MOVE
OVER THESE AREAS. SOME LIGHT PCPN WILL REMAIN...HOWEVER WE COULD
SEE IT TRANSITION TO FZDZ AS THE DGZ BECOMES UNSATURATED.
BY THE TIME PCPN REACHES THE NRN PORTION OF THE CWFA...THE COLUMN
SHOULD BE MAINLY COLD ENOUGH TO SUPPORT MAINLY SNOW. THE SNOW SHOULD
START OUT LIGHT...AND PICK UP LATE TONIGHT/SUN MORNING AS THE BEST
DEFORMATION SLIDES ACROSS THE NRN COUNTIES AND NW OF THE CWFA. SNOW
AMOUNTS ARE GENERALLY EXPECTED TO REMAIN IN THE ADVISORY CATEGORY AS
THE UPPER LOW EJECTING WILL HAVE OPENED UP BY THE TIME IT REACHES
HERE AND THE FGEN IN THE DEFORMATION WILL NOT BE AS STRONG AS TO OUR
SW. ONE THING GOING FOR BETTER SNOW AMOUNTS HERE IS THE FACT THAT
THE DGZ IS EXPECTED TO REMAIN SATURATED AS THE DRY SLOT REMAINS SE
OF THIS AREA.
THE CAVEAT TO ALL OF THIS IS IF THE OUTLIER NAM IS CORRECT...ALL OF
THIS WOULD BE SHIFTING TO THE NW A LITTLE. WE BELIEVE AT THIS TIME
THAT WE HAVE A GOOD CONSENSUS OF THE TRACK OF THE SYSTEM WITH GOOD
RUN TO RUN CONSISTENCY FROM MOST OF THE GLOBAL MODELS AND IT SHOULD
BE WELL SAMPLED BY NOW WITH IT BEING WELL WITHIN THE RAOB NETWORK.
WE WILL SEE A TRANSITION TO SOME LAKE EFFECT SNOW SHOWERS ON SUN
NIGHT AS COLDER AIR COMES IN BEHIND THE SYSTEM. THE FLOW SHOULD BE
NNW WHICH WOULD FAVOR THE IMMEDIATE LAKESHORE FOR BEST SNOW SHOWER
CHANCES. THERE IS SOME DECENT MOISTURE UP THROUGH 15K FEET AND
OVER-LAKE INSTABILITY IS SUFFICIENT.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 329 AM EST SAT DEC 21 2013
THE UPCOMING CHRISTMAS WEEK WILL BE MORE LIKE WHAT WE HAVE SEEN FOR
MUCH OF DECEMBER: COLDER THAN NORMAL WITH FREQUENT CHANCES FOR SNOW
SHOWERS. THE NORTHERN BRANCH OF THE JET AND ARCTIC AIR WILL DOMINATE
THROUGHOUT THE WEEK... WITH SEVERAL SHORTWAVES AND SFC
TROUGHS/FRONTS SWINGING THROUGH THE GRTLKS RGN. TEMPERATURES ARE
EXPECTED BE BELOW FREEZING ALL WEEK... AND THE COLDEST DAY OF THE
WEEK WILL BE TUESDAY WHEN HIGHS SHOULD STRUGGLE TO REACH 20 BEHIND
THE FIRST NRN STREAM WAVE.
GFS/ECMWF ARE IN GOOD AGREEMENT SHOWING A POTENT SHORTWAVE IMPACTING
THE AREA MONDAY AFTERNOON AND NIGHT. SNOW SHOWERS ARE LIKELY AND
LAKE ENHANCEMENT WILL BE IN PLAY AS THIS FEATURE COMES THROUGH.
HOWEVER CONFIDENCE IN WIND DIRECTION IS LOW SINCE MODELS INDICATE A
WEST TO EAST ORIENTED SFC TROUGH SETTING UP SOMEWHERE ACROSS LWR MI
AND ARE NOT IN GREAT AGREEMENT WITH IT/S LOCATION AND RESULTANT
WINDS. NEVERTHELESS THE TROUGH SHOULD RESULT IN LOCALLY ENHANCED
CONVERGENCE WITH A LARGE PORTION OF THE CWFA SEEING SNOW SHOWERS AND
AT LEAST SOME LIGHT ACCUMULATIONS. IF A WESTERLY FLOW DEVELOPS THEN
AREAS ALONG AND WEST OF HWY 131 COULD SEE SEVERAL INCHES BUT AGAIN
WIND DIRECTION IS VERY QUESTIONABLE AT THIS TIME.
A BRIEF PERIOD OF SHORTWAVE RIDGING MOVES ACROSS FOR TUESDAY
AFTERNOON AND EVENING... THEN SOME WAA/ISENTROPIC LIFT LIGHT SNOW
POSSIBLE ON CHRISTMAS DAY AHEAD OF THE NEXT APPROACHING SHORTWAVE.
THE ECMWF HAS A MUCH STRONGER SHORTWAVE THAN THE GFS FOR THE 26TH
AND WOULD SUGGEST A DECENT ROUND OF ACCUMULATING LAKE ENHANCED SNOW
SHOWERS FOR THURSDAY AND THURSDAY NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 706 AM EST SAT DEC 21 2013
WIDESPREAD LIFR CONDITIONS DUE TO LOW CLOUDS AND FOG WILL CONTINUE
TO PLAGUE ALL OF THE TERMINALS TODAY AND TONIGHT. FREEZING RAIN WILL
BREAK OUT AGAIN THIS AFTERNOON... STARTING EARLY THIS AFTERNOON
ALONG THE I-94 CORRIDOR THEN SPREADING NORTH TO THE I-96 CORRIDOR
BY LATE AFTERNOON WHERE SOME SLEET AND SNOW MAY MIX WITH THE FREEZING
RAIN AT THE ONSET. MKG SHOULD TEND TO BE MOSTLY SNOW AND SLEET AS
PRECIP DEVELOPS THERE EARLY THIS EVENING.
THE INTENSITY OF THE FREEZING RAIN/ICING IS EXPECTED TO BE
HEAVIEST DURING THE EVENING HOURS THEN DIMINISH AFTER 06Z TONIGHT.
MKG SHOULD BE THE EXCEPTION TO THIS... WHERE SNOW WILL CONTINUE
OVERNIGHT.
&&
.MARINE...
ISSUED AT 534 PM EST FRI DEC 20 2013
NORTHEAST FLOW WILL CONTINUE INTO SATURDAY NIGHT. THIS OFFSHORE FLOW
WILL HELP KEEP WAVES LOWER. HOWEVER AS WINDS PIVOT TO THE NORTH
NORTHWEST LATE SATURDAY NIGHT/EARLY SUNDAY MORNING WAVES WILL BUILD
AND WE WILL LIKELY NEED A SMALL CRAFT ADVISORY BY THEN.
&&
.HYDROLOGY...
ISSUED AT 325 PM EST FRI DEC 20 2013
THE FORECAST TREND IS TOWARDS LESS QPF OVER THE WEEKEND AS THE
TRACK OF THE LOW LOOKS TO STAY FURTHER SOUTH AND EAST OF THE RIVER
BASINS IN SOUTHWEST LOWER MICHIGAN. TOTAL QPF IS NOW EXPECTED TO
BE LESS THAN AN INCH FOR THE HEADWATERS OF THE GRAND AND ST.
JOSEPH BASINS.
SHARP RISES ARE STILL POSSIBLE AT THE JACKSON FORECAST POINT ON
THE GRAND RIVER AND WE WILL HAVE TO WATCH THE MODEL TRENDS CLOSELY
TONIGHT AND THE ACTUAL STORM DEVELOPMENT ON SATURDAY. SNOW MELT
COULD ALSO CONTRIBUTE TO RISES ACROSS THE ST. JOSEPH AND KALAMAZOO
BASINS BEFORE THE ARCTIC AIR RETURNS ON MONDAY...WITH ICE
REFORMING ON THE RIVERS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO NOON EST
SUNDAY FOR MIZ051-052-056>059-064-065-071-072.
ICE STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST SUNDAY
FOR MIZ066-067-073-074.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST
SUNDAY FOR MIZ037>040-043>046-050.
LM...NONE.
&&
$$
UPDATE...TJT
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...OSTUNO
MARINE...JK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
643 AM EST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 457 AM EST SAT DEC 21 2013
SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN
STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES
ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT
LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW
WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA
UNTIL DAYBREAK ON SUNDAY.
EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN
LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF
ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK
SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT
SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF
OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW
TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP
TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO
THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC
TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT.
EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY
GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE
OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR
REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED
LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO
5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE
AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT
SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT
WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW
TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS.
CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE
THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS
ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS.
THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN
KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS
AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT
EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4
INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE
MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS
ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF
SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN.
ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1
INCH.
MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH
EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL
MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM
TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER
MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY
PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS
TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES
MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS
INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK
SUPERIOR.
SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON
THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF
LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85
AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF
WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING
WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR
SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE
INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL
CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS
MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS
THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS
WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR
SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE
EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE
SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 457 AM EST SAT DEC 21 2013
HAVE OPTED TO ISSUE A WINTER STORM WATCH FOR THE TERRAIN/LAKE
ENHANCED AREAS OF MARQUETTE/BARAGA COUNTIES AS WELL AS GOGEBIC AND
ONTONAGON COUNTIES FOR SUNDAY AND MONDAY. LONG DURATION LAKE
ENHANCED/LAKE EFFECT SNOW EPISODE LOOKING MORE POSSIBLE NOW AS THE
MODELS ARE STARTING TO COME INTO BETTER AGREEMENT INTO A MAIN LOW
TRACK THROUGH SOUTHERN MI ON SUNDAY. HOWEVER...THE COMPLEX
INTERACTION BETWEEN THE SOUTHERN STREAM ENERGY MOVING THROUGH THE
LOWER LAKES AND THE NORTHERN STREAM TROUGH MOVING INTO THE UPPER
MIDWEST MAKES THIS FORECAST CONFIDENCE STILL SOMEWHAT BELOW AVERAGE.
ONTO THE DETAILS...AS SAID ABOVE THE NWP SUITE HAVE COME INTO BETTER
AGREEMENT WITH THE MAIN LOW MOVING THROUGH SOUTHERN LOWER MICHIGAN
WITH THE SOUTHERN STREAM IMPULSE MOVING OUT OF THE PLAINS. EXPECT
SYNOPTIC MOISTURE AND LIFT TO GLANCE BY THE SOUTHEAST FORECAST AREA
SUNDAY MORNING INTO EARLY AFTERNOON AS THE COMMA HEAD/DEFORMATION
ZONE PCPN MOVES THROUGH. THIS TRACK WILL ALLOW FOR 1000-850MB WINDS
TO TURN NE AND SHOULD ALLOW FOR LAKE ENHANCEMENT TO ALSO DEVELOP IN
MARQUETTE/BARAGA COUNTIES AS WELL AS THE FAR WEST NEAR IRONWOOD.
CONSENSUS QPF FROM THE NWP SUGGEST ABOUT 0.20-0.30 INCH OF QPF NEAR
LAKE MICHIGAN AND FAR EAST ON SUNDAY...WITH MUCH LESSER AMOUNTS WELL
INLAND AWAY FROM FROM LAKE SUPERIOR. THIS ALSO SEEMS REASONABLE
GIVEN THAT 700MB MIXING RATIOS REMAIN AROUND 2 G/KG THROUGH EARLY
AFTERNOON. GIVEN THAT SOME OF THE LIFT WILL BE IN THE DGZ AREA
ACROSS THE SOUTH DURING THE DAY...WE SHOULD SEE SNOW RATIOS ACROSS
THE FAR SOUTHEAST AROUND 15-17:1 DURING THE DAY WHICH WOULD EQUATE
TO 3-5 INCHES OF SNOW BY EVENING. MOST LIKELY AN ADVISORY WILL BE
NEEDED IN THIS AREA ON SUNDAY...BUT WILL HOLD OFF SINCE THIS WILL BE
GENERALLY A 3RD PERIOD ADVY.
AS FOR AREAS CLOSER TO LAKE SUPERIOR...ALL OF THE NWP GUIDANCE SHOW
PBL WINDS STAYING NELY THROUGH THE DAY WHICH SHOULD ALLOW FOR
TERRAIN ENHANCED SNOW TO COMMENCE IN THE NE FLOW FAVORED AREAS
DESPITE THE RELATIVELY WEAK SYNOPTIC LIFT. WITH THE BEST LIFT BEING
CONFINED TO GENERALLY BELOW THE DGZ...EXPECT SNOW RATIOS BE BE
FAIRLY LOW WITH ONLY AROUND 13:1. WILL GENERALLY GO WITH 4 OR 5
INCHES AT MOST IN THESE AREAS...BUT GIVEN THE STRONG AND DEEP NE
FLOW...WOULD NOT BE SHOCKED IF QPF AND THUS SNOWFALL IS MORE ON
SUNDAY.
THEN ON SUNDAY NIGHT...DIFFERENCE START TO DEVELOP WITH THE MODELS
REGARDING THE EVOLUTION OF THE NORTHERN STREAM UPPER TROUGH. THE NAM
IS CERTAINLY THE MOST AGGRESSIVE IN CLOSING OFF THE LOW AND
SETTLING OVER THE UPPER GREAT LAKES...WHICH ALLOW FOR A STRONG
INVERTED TROUGH TO HANG BACK ACROSS THE CENTRAL GREAT LAKES THROUGH
MONDAY. MEANWHILE...THE GFS GENERALLY KEEPS THE UPPER TROUGH OPEN
AND MOVES IN THROUGH THE AREA BY MONDAY AFTERNOON. THE LATEST 00Z
ECMWF IS INTERESTING AS IT ALSO ATTEMPT TO CLOSE OFF THE LOW SUN
NIGHT BUT IS NOT NEARLY AS DEEP AS THE NAM FORECASTS.
NONETHELESS...THE ECMWF ALSO SUGGESTS THAT THERE WILL BE SOME TYPE
OF INVERTED TROUGH EXTENDING BACK INTO THE AREA THROUGH MONDAY AND
OUR LOCALLY PRODUCE ARW-WRF USING THE GFS AS BOUNDARY CONDITIONS
ALSO SUGGEST THAT THERE WILL BE A INVERTED TROUGH HANGING BACK
THROUGH MONDAY. AS SUCH...DO NOT THINK THE PBL WINDS WILL SHIFT TO
N-NW AS FAST AS THE GFS AND ECMWF SUGGEST. IN FACT...THE CURRENT
THINKING IS THAT THE WINDS WILL STAY NORTHERLY OR PERHAPS A LITTLE
EAST OF NORTH THROUGH MONDAY WITH THIS TROUGH STAYING SOUTH OF THE
AREA. WITH ALL OF THIS SAID...THE EXPECTATION IS THAT THE SNOW WILL
TRANSITION TO MORE LAKE ENHANCED VARIETY AND PERSIST RIGHT THROUGH
MONDAY BEFORE THE UPPER TROUGH SWINGS THROUGH AND ALLOWS THE WIND TO
GRADUALLY SHIFT TO THE N-NW BY MON EVENING. AS SUCH...EXPECT
MODERATE TO LOCALLY HEAVY SNOW TO CONTINUE IN MQT/BARAGA COUNTIES AS
WELL AS GOGEBIC COUNTY THROUGH THE NIGHT SUNDAY INTO MONDAY. THE
BEST LIFT RAPIDLY BECOMING ENTRENCHED IN THE DGZ SUNDAY EVENING AS
THE UPPER TEMPS DROP...EXPECT THE SNOW TO BECOME MUCH MORE FLUFFY
BUT ALSO ACCUMULATE MUCH FASTER WITH RATIOS CLOSE TO 25:1 BY MON
MORNING. SOME AREAS IN THE WATCH AREA COULD SEE ANOTHER 8-12 INCHES
OF SNOW SUN NIGHT INTO MONDAY.
INTERESTINGLY...THERE ARE SEVERAL VERY GOOD CIPS ANALOG EVENTS FOR
THIS SYSTEM. THEY ALL GENERALLY SHOW THE WATCH AREA SEEING
SIGNIFICANT 72 HOUR SNOWFALL. NOT SURE IF WE WILL SEE ANY LONGER
PERIOD OF HEAVY SNOWFALL...RATHER I AM THINKING THAT IT WILL BE
GENERALLY A PERSISTENT SNOWFALL FOR 24-36 HOURS WHICH WILL ALLOW
WARNING CRITERIA TO BE REACHED. EVEN MORE INTERESTING...DESPITE THE
FACT THAT GOGEBIC COUNTY WILL BE FURTHEST REMOVED FROM THE
SYSTEM...THE CURRENT NWP AND ALSO THE CIPS GUIDANCE SUGGEST THAT
THIS AREA COULD SEE THE MOST SNOWFALL OUT OF THIS EVENT. WE WILL
SEE...
ANY REMAINING LES SHOULD END RAPIDLY MON NIGHT/TUE MORNING AS THE
HIGH PRES RIDGE BUILDS ACROSS THE FORECAST AREA. STILL LOOKS QUITE
COLD TUE MORNING ACROSS THE WEST WITH LIGHT WINDS/CLEAR SKIES. TEMPS
10-20 BELOW NOT OUT OF THE QUESTION IN THE NORMALLY COLDER SPOTS.
THE ECMWF AND GEM ARE IN GOOD AGREEMENT IN LIGHT OVERRUNNING/WARM
ADVECTION SNOW CHRISTMAS EVE NIGHT INTO CHRISTMAS DAY ACROSS THE
ENTIRE FORECAST AREA. SOME HINTS THAT THERE MIGHT BE SOME LAKE
ENHANCEMENT OFF OF LAKE MICHIGAN TUESDAY NIGHT AND HAVE OPTED TO
CONTINUE LIKELY POPS ACROSS THE EASTERN PART OF THE FORECAST AREA
TUE NIGHT INTO CHRISTMAS DAY. SOME DIFFERENCES EMERGE THU INTO
FRIDAY REGARDING THE EVOLUTION AND THE TROUGH WITH THE ECMWF BEING
DEEPER AND FURTHER SOUTH COMPARED TO THE GFS. REGARDLESS...SENSIBLE
WEATHER SHOULD GENERALLY THE SAME WITH EITHER MODEL WITH LES IN THE
NW FAVORED SNOWBELTS CHRISTMAS NIGHT INTO THU NIGHT BEFORE
DIMINISHING ON FRIDAY AS HIGH PRES BUILDS OVERHEAD. TEMPS STILL LOOK
BELOW NORMAL THROUGH THE EXTENDED WITH 850MB TEMPS -20 TO -25C WED
NIGHT/THU WARMING TO -15 TO -20C BY FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 640 AM EST SAT DEC 21 2013
WITH ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS ACROSS THE
REGION...MAINLY MVFR CIGS ARE EXPECTED THROUGH THE FCST PERIOD AT
CMX AND IWD. EXPECT LAKE EFFECT SNOW SHOWERS TO DEVELOP AT CMX LATER
TODAY AND THESE WILL CONTINUE THROUGH TONIGHT. IFR VSBY IS EXPECTED
IN THE SNOW AND ALSO DUE TO BLSN WITH GUSTY EAST WINDS DEVELOPING.
SNOW SHOWERS WILL BEGIN TO AFFECT IWD LATE TONIGHT AS WINDS BECOME
MORE NORTHEAST. WEAK DOWNSLOPE WESTERLY FLOW AT SAW WILL FAVOR VFR
CONDITIONS UNTIL LATE THIS AFTERNOON WHEN WINDS VEER TO THE NNE AND
UPSLOPE FLOW LEADS TO MVFR CIGS AND SOME LIGHT SNOW SHOWERS. WINDS
BECOMING MORE EASTERLY WILL SCATTER OUT THE LOW CLOUDS AT SAW LATE
TONIGHT. WIDESPREAD SNOW IS EXPECTED TO IMPACT ALL TERMINALS ON
SUNDAY AS A LOW PRESSURE SYSTEM SLIDES ACROSS THE CENTRAL GREAT
LAKES REGION. HEAVIEST SNOW WILL OCCUR AT IWD WITH UPSLOPE NORTHEAST
WINDS PROVIDING ADDITIONAL SUPPORT FOR SNOW OFF LK SUPERIOR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 457 AM EST SAT DEC 21 2013
LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS
SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS
OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW
PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER
THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW
PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE
FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE
UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH
PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A
LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES.
THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE
SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON
WEDNESDAY...WINDS WILL BECOME WESTERLY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING
FOR MIZ002-004-005-009.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...MRD
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1022 AM EST SAT DEC 21 2013
.SYNOPSIS...WARM SOUTHERLY FLOW AROUND BERMUDA HIGH PRESSURE WILL
CONTINUE THIS WEEKEND...AHEAD OF A MOISTURE-LADEN COLD FRONT THAT
WILL CROSS OUR REGION SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1020 AM SATURDAY...
TODAY: A WARM/MILD DAY IS EXPECTED TODAY ACROSS CENTRAL NC... WITH
HIGH PRESSURE AT THE SURFACE AND ALOFT REMAINING ANCHORED OFF THE
SOUTHEAST U.S. COAST. THIS WILL RESULT IN A CONTINUED
WARM/MOISTENING DEEP SOUTH TO SOUTHWESTERLY RETURN FLOW ACROSS OUR
AREA. LOW LEVEL FLOW IS EXPECTED TO STRENGTHEN TODAY AS A POTENT S/W
LIFTS NORTHEASTWARD INTO THE SOUTHERN PLAINS OUT OF WEST TEXAS. THE
MAIN LOW LEVEL JET IS EXPECTED TO REMAIN TO THE WEST OF THE AREA
TODAY... WITH THE THE SURFACE FRONT EXPECTED TO SLOWLY SHIFT
EASTWARD ACROSS THE OHIO RIVER VALLEY AND ARK-LA-TEX REGIONS TODAY.
THUS... THINK THE BULK OF ANY LIGHT SHOWER ACTIVITY WILL GENERALLY
REMAIN JUST TO THE WEST OF OUR AREA TODAY. THE BIG QUESTIONS THAT
REMAIN... IS HOW MUCH CLOUD COVER WE WILL HAVE TODAY AND THE IMPACTS
ON HIGH TEMPS. THE LATEST GFS AND RAP ARE MORE AGGRESSIVE THAN THE
NAM WRT TO LOW LEVEL CLOUD COVER TODAY... ESPECIALLY ACROSS OUR
WESTERN REACHES. IN ADDITION... ALL MODEL GUIDANCE CONDITIONS TO
SHOW MID AND HIGH LEVEL CLOUD COVER STREAMING ACROSS THE REGION
TODAY... AT TIMES THICKER... AS WEAK EMBEDDED IMPULSES MOVE THROUGH
THE SOUTHWESTERLY FLOW ALOFT. FOR NOW WILL TREND THE FORECAST A
LITTLE BIT MORE TOWARDS THE GFS/RAP (WHICH IS A GOOD BLEND BETWEEN
THE GUIDANCE) GIVEN THE EXPECTED STRENGTHENING OF THE LOW LEVEL FLOW
AND QUITE A BIT OF LOW LEVEL CLOUD COVER TO THE SOUTH-SOUTHWEST OF
THE REGION CURRENTLY (ACROSS THE UPSTATE OF SC). GIVEN THIS... WILL
TRIM HIGHS BACK BY A DEGREE OR TWO ACROSS THE WESTERN HALF OF THE
AREA. STILL THESE HIGHS WILL BE NEAR OR ABOVE RECORD VALUES FOR TODAY.
EXPECT HIGHS TEMPS WILL RANGE FROM THE UPPER 60S NEAR 70 NW TO THE UPPER
70S SE. -77
TONIGHT: SKIES WILL LIKELY LARGELY CLEAR FOR A TIME THIS EVENING AND
EARLY TONIGHT...AS THE FLOW ALOFT BACKS IN RESPONSE TO THE APPROACH
OF THE DEAMPLIFYING UPPER LOW FROM WEST TX...AND FURTHER RIDGE
AMPLIFICATION OVER THE CARIBBEAN...AND CONSEQUENTLY BOWS THE MID-
HIGH CLOUDINESS NORTHWESTWARD TOWARD THE APPALACHIANS. THIS WILL SET
THE STAGE FOR A HIGHER-THAN-PREVIOUS-DAYS PROBABILITY AND COVERAGE
OF STRATUS OVERNIGHT...AMIDST A STEADILY STRENGTHENING WAA REGIME.
THIS PATTERN ALSO SUPPORTS THE INHERITED CHANCE OF SHOWERS OVER THE
WESTERN PIEDMONT...WHOSE DEPTH WILL BE LIMITED BY A CAPPING
INVERSION ALOFT PER BUFR FORECAST SOUNDINGS...AND A LACK OF MORE
APPRECIABLE LOW LEVEL MOISTURE AND RELATED INSTABILITY. MILD WITH
LOWS IN THE LOWER TO MIDDLE 60S - ALSO AROUND RECORD HIGH MINS FOR
THE DATE. -26
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 305 AM SATURDAY...
DEEP SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING COLD FRONT WILL TAP
INTO GULF MOISTURE... BRINGING PWS OF OVER 1.5 INCHES TO THE AREA
SUNDAY... NEAR MAX VALUES RECORDED FOR DECEMBER. HEAVY RAINFALL WILL
BE A POTENTIAL CONCERN... MAINLY OVER URBAN AREAS AS QPF REMAINS
SHORT OF FLASH FLOOD GUIDANCE AT THIS TIME. MID LEVEL LAPSE RATES
REMAIN WEAK... AND INSTABILITY LOW... SO THE SEVERE THREAT REMAINS
NEGLIGIBLE. ANY STORMS THAT DO DEVELOP MAY TAP IN TO THE STRONG 60-
65 KT LLJ AND BRING THE POTENTIAL FOR STRONG GUSTY WINDS ALONG WITH
HEAVY RAINFALL. SHEAR PROFILES WOULD BE SUPPORTIVE OF ROTATION...
HOWEVER THIS GOES STRONGLY AGAINST CLIMATOLOGY AND WITH THE
AFOREMENTIONED ENVIRONMENT... THIS IS A VERY LOW END THREAT. NEAR
RECORD HIGHS IN THE 70S.
THE COLD FRONT CROSSES THE AREA MONDAY AFTERNOON... MAKING IT TO THE
CAROLINA COAST BY 03Z TUES. HIGHS IN THE 60S. SHOWERS WILL END FROM
WEST TO EAST DURING THE EVENING HOURS. LOWS IN THE 30S WITH STRONG
COLD ADVECTION.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 307 AM SATURDAY...
UPPER LEVEL TROUGH MOVES OFF THE EAST COAST ON TUESDAY... AND THE
COLUMN DRIES SIGNIFICANTLY AS UPPER LEVEL FLOW BECOMES WESTERLY.
HIGH PRESSURE OVER THE MISSISSIPPI VALLEY ON TUESDAY WILL BUILD OVER
THE EAST COAST WEDNESDAY. HIGHS IN THE 40S ON TUESDAY AND WEDNESDAY
WILL MODERATE TOWARD NORMAL... IN THE 50S... THURSDAY THROUGH FRIDAY.
AN UPPER LEVEL TROUGH OVER CENTRAL US ON THURSDAY WILL MOVE EASTWARD
THROUGH THE END OF THE PERIOD... WITH DIFFERENCES ARISING FROM
SHORTWAVES MOVING THROUGH THE FLOW DURING THIS TIME. WILL INTRODUCE
SLIGHT CHANCE POPS FOR FRIDAY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 750 AM SATURDAY...
GENERALLY VFR CONDITIONS EARLY THIS MORNING...ASIDE FROM VISIBILITY
RESTRICTIONS IN FOG AT KFAY...WILL LIKELY TRANSITION THROUGH A FEW
HOUR PERIOD OF MVFR/IFR CEILINGS BETWEEN 13-16Z AT ALL BUT THE TRIAD
TERMINALS...AS DIURNAL HEATING ACTS UPON AN INCREASINGLY MOIST AIR
MASS NEAR THE SURFACE. CONFIDENCE OF THIS SUB-VFR OCCURRENCE IS
ABOUT 50 PERCENT...AND MOST LIKELY AT KFAY. VFR CONDITIONS WITH A
BREEZY SSW WIND WILL OTHERWISE PREVAIL THROUGH THE THIS
EVENING...BEFORE WIDESPREAD LIFR/VLIFR STRATUS DEVELOPS BETWEEN 03-
07Z TONIGHT. A LITTLE PATCHY DRIZZLE MAY ALSO ACCOMPANY THE STRATUS.
LOOKING AHEAD: SHOWERS WILL BECOME NUMEROUS ACROSS THE AREA FROM
WEST TO EAST SUNDAY INTO SUNDAY NIGHT WITH WIDESPREAD SUB-VFR
CONDITIONS IN RAIN...POSSIBLY HEAVY AT TIMES...CONTINUING THROUGH
MONDAY AFTERNOON...AS A SLOW MOVING COLD FRONT PUSHES EAST THROUGH
THE AREA. VFR CONDITIONS ARE EXPECTED TO RETURN BY TUESDAY AND
CONTINUE THROUGH THE REMAINDER OF THE PERIOD.
&&
.CLIMATE...
AS OF 230 PM WEDNESDAY...
DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS:
RALEIGH/DURHAM...
HIGHHI MIN
DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011
--------------------------------------------------------------------
GREENSBORO...
HIGHHI MIN
DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984
DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011
--------------------------------------------------------------------
FAYETTEVILLE...
HIGHHI MIN
DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...26
NEAR TERM...77/26
SHORT TERM...30
LONG TERM...30
AVIATION...26/CBL
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
551 AM EST SAT DEC 21 2013
.SYNOPSIS...
FRONT APPROACHES FROM THE WEST TODAY...PASSES AS COLD FRONT SUNDAY.
SNOW SHOWERS POSSIBLE MONDAY NIGHT INTO TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SURFACE BOUNDARY HAS BEEN SHIFTING EAST SLOWLY THROUGH THE NIGHT AND
CURRENTLY RUNS FROM CENTRAL TEXAS NORTHEAST TO THE WESTERN SHORES
LAKE ERIE. ONE WAVE IS NEAR DETROIT AND LIFTING NE...DRIVING PRECIP
BISECTING OHIO. NEXT WAVE IS LIFTING INTO ARKANSAS WHICH IS MAYBE
JUST A BIT FASTER THAN THE LOWER RES MODELS...BUT REPRESENTED FAIRLY
WELL BY HIGHER RES MODELS LIKE HRRR AND RAP. SO TRENDED TOWARDS
THESE HIGHER RES MODELS FOR POPS THIS MORNING AS THE WAVE MOVES INTO
THE LOWER OHIO RIVER VALLEY WITH LIKELY POPS INTO SE OHIO. ANOTHER
WAVE IS STARTING TO TAKE SHAPE IN EASTERN TEXAS WHICH WILL DRIVE
ANOTHER AREA OF HIGHER POPS INTO SE OHIO TONIGHT. HAVE A BREAK
BETWEEN THE TWO WAVES...BUT STILL HAVE SLIGHT CHANCE POPS EAST AND
CHANCE POPS WEST THIS EVENING. THIS WILL ALSO BE THE WAVE THAT GETS
THE BOUNDARY MOVING EAST AGAIN...SO HAVE THE FRONT JUST WEST OF CWA
BORDER BY 12Z SUNDAY. NOT A WHOLE LOT OF INSTABILITY TODAY...BUT
850MB FLOW PUSHES 70-80KTS LATE THIS AFTERNOON INTO TONIGHT ACROSS
WESTERN CWA...MAINLY IN SE OHIO AND NE KENTUCKY. THIS MATCHES SPCS
SLIGHT RISK...AND WHILE THUNDER IS NOT EXPECTED...STRONGER SHOWERS
SHOULD STILL BE ABLE TO TAP INTO THIS AND PRODUCE SOME ENHANCED
OUTFLOW WINDS. WILL MENTION POTENTIAL FOR STRONG OUTFLOWS IN HWO FOR
SE OHIO AND NE KY COUNTIES. DO HAVE SLIGHT CHANCE OF THUNDER JUST
AHEAD OF THE FRONT EARLY SUNDAY MORNING...ANTICIPATING STRONG DYNAMIC
FORCING. STILL...NOT EXPECTING WIDESPREAD THUNDER...BUT A RUMBLE OR
TWO CANNOT BE RULED OUT.
PLACEMENT OF HIGHEST QPF STILL LOOKS TO STAY WEST OF CWA...JUST
CLIPPING NW CORNER LATE THIS AFTERNOON INTO TONIGHT...SO WILL NOT
MAKE ANY CHANGES TO FLOOD WATCH AT THIS POINT.
LITTLE TO NO CHANGE MADE TO HIGHS TODAY...GOING WELL ABOVE NORMAL
FOR THE WINTER SOLSTICE. DID WARM UP LOWS TONIGHT A COUPLE
DEGREES...AND WENT WITH A NON-DIURNAL TREND WITH NEARLY STEADY TEMPS
THROUGH THE EARLY MORNING OUT AHEAD OF THE COLD FRONT. NOT THAT ITS
AN OFFICIAL CLIMATE STATISTIC...BUT COULD BE CLOSE TO SETTING SOME
RECORD HIGH MINIMUMS.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SFC LOW WILL BE QUICKLY PUSHING NORTHEAST FROM ROUGHLY CENTRAL
INDIANA TO THE EASTERN GREAT LAKES BTWN 12Z SUN AND 00Z MON.
ATTENDANT COLD FRONT ALSO PROGGED TO BE JUST OUTSIDE THE WESTERN
ZONES BY 12Z SUN AND WILL BE QUICKLY PUSHING ACROSS AS WELL. OVERALL
FORECAST GENERALLY STILL ON TRACK...BUT DID SLOW DOWN THE
PROGRESSION OF PRECIP ACROSS THE FORECAST AREA FROM WEST TO EAST BY
ABOUT TWO-THREE HOURS...WITH THE HIGHEST CHANCE OVER THE WEST ZONES
BY 12Z...CENTRAL ZONES BY 15Z...AND MOST PRECIP EAST OF THE I79
CORRIDOR BY 18Z. CONSENSUS OF MODEL OUTPUT STILL DEPICTING ABOUT
50KTS AT 925MB AND 70-80KTS AT 850MB. SPC HAS EXPANDED ITS SLIGHT
RISK AREA OF SEVERE THUNDERSTORMS TO INCLUDE MOST OF THE SE OHIO AND
NE KY COUNTIES. THE THREAT FOR A BRIEF SVR WIND GUST EXISTS FOR MOST
LOCATIONS PRETTY MUCH ANYWHERE ALONG AND WEST OF I79 SUNDAY MORNING
PRIMARILY AS THE MAIN CONVECTIVE LINE MARCHES ACROSS...BUT CERTAINLY
THE SE OHIO COUNTIES ARE MOST PRONE TO THIS POSSIBILITY AS THE ASSOC
LOWS AT 925MB AND 850MB MOVE NORTHEAST WITH THE SFC LOW. STILL
EXPECTING GENERALLY A HALF INCH OR SO OF PRECIP WITH SOME HIGHER
AMOUNTS AHEAD OF AND WITH THE FRONT. FOR MAX TEMPS...MOS GUIDANCE
CONTINUING TO INSIST ON LOWER 70S. WENT LOWER THAN THIS HOWEVER WITH
ONGOING CLOUDS AND PRECIP DURING THE MORNING HOURS AS COLD ADVECTION
IS BEGINNING...SHOULD STILL BE IN THE LOW/MID 60S. MAY ACTUALLY SEE
A FEW BREAKS IN THE CLOUDS ACROSS THE WESTERN ZONES BY 18Z-21Z...BUT
BY THIS TIME 925MB AND 850MB TEMPS CONTINUE TO LOWER TO READINGS
WHICH WOULD ONLY SUPPORT PERHAPS THE MID 60S ACROSS THOSE LOCATIONS.
PRECIP WILL WIND DOWN DURING THE AFTERNOON HOURS EVEN FOR THE
MOUNTAINS AS DEEP LAYER MOISTURE CONTINUES EASTWARD. ANOTHER
DEVELOPING WAVE ALONG THE FRONT HOWEVER WILL QUICKLY BRING A RETURN
TO PRECIP CHANCES MAINLY BTWN 06Z-12Z MON. THIS NEXT SFC WAVE WILL
SLOW/DELAY THE COLD PUSH OF AIR INTO THE AREA. IN FACT...HAVE HOURLY
TEMPS STILL IN THE LOWER 50S AROUND 06Z-08Z FOR LOWLANDS EAST OF
I79...WITH MUCH COOLER TEMPS ACROSS THE SE OHIO ZONES. AS THIS NEXT
SFC LOW ALSO PASSES TO THE NORTHEAST...WINDS WILL FINALLY COME
AROUND TO THE NORTHWEST ALLOWING FOR THE COLD AIR TO FILTER FULLY
INTO THE AREA. CODED UP SOMEWHAT OF A NON-DIURNAL TEMP CURVE FOR
MONDAY...WITH SOME MODEST RECOVERY OF TEMPS ACROSS THE FAR NW
ZONES...NEARLY STEADY TEMPS ACROSS THE CENTRAL AREAS...AND TEMPS
CONTINUING TO SLOWLY DROP DURING THE DAY ACROSS THE EASTERN
MOUNTAINS. SKIES SHOULD REMAIN MOSTLY CLOUDY TO CLOUDY FOR MOST WITH
THIS COLD ADVECTION...BUT AGAIN MAY SEE SOME LATE DAY BREAKS FOR THE
CENTRAL AND WEST ZONES.
A COLD NIGHT IS IN STORE FOR THE AREA MONDAY NIGHT/TUE MORNING.
SHOULD SEE MORE CLOUDS AND ANOTHER INCREASING CHANCE OF LIGHT
SNOW/FLURRIES...ESPECIALLY ACROSS THE NORTH...TOWARDS THE DAWN HOURS
TUE AS THE UPPER TROUGH FINALLY BEGINS TO SHIFT EASTWARD...WITH
TROUGH AXIS PROGGED TO BE LOCATED OVER LAKE HURON SOUTH INTO OHIO BY
12Z TUE. LOWERED MINS JUST A BIT INTO THE LOWER 20S WITH LOW
DEWPOINTS...BUT STAYED ABOVE THE LOWEST GUIDANCE WITH AFOREMENTIONED
CLOUD COVER AND A CONTINUED 10-15KT BREEZE IN THE BOUNDARY LAYER.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
SOME UPSLOPE SNOW POSSIBLE MONDAY NIGHT INTO TUESDAY AS COLD AIR
MOVES INTO THE REGION ON NORTHWEST FLOW. HIGH PRESSURE THEN BUILDS
IN FOR CHRISTMAS DAY. USED THE ECMWF MEAN FOR THURSDAY AND
FRIDAY...WHICH WOULD SHOW A FRONT MOVING THROUGH ON THURSDAY. BIG
QUESTION ON FRIDAY IS HOW MUCH COLD AIR RESIDES BEHIND THE FRONT AND
WHETHER ANY SNOW SHOWERS WILL BE ASSOCIATED WITH IT. WENT DRY FOR
NOW AS PER MEAN...BUT CONFIDENCE IS NOT HIGH.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
IN GENERAL...VFR EXPECTED THROUGH MUCH OF THE DAY AT THE TAF
SITES...HOWEVER COULD GET A PASSING MVFR CIG THIS MORNING. EXPECT
MVFR TO IFR ACROSS SE OHIO...CLOSER TO A NEARLY STALLED SURFACE
BOUNDARY. WILL ALSO HAVE BETTER CHANCE OF PRECIP TODAY ACROSS SE
OHIO...BEFORE THE CHANCES OF RAIN INCREASE FROM WEST TO EAST THROUGH
TONIGHT AS THE SURFACE BOUNDARY APPROACHES. WILL HAVE DROPS INTO
MVFR AND IFR IN THE WEST TOWARD THE END OF THE TAF PERIOD.
STRONG SW FLOW ALOFT WILL CONTINUE THROUGH THE TAF PERIOD WHICH WILL
RESULT IN SURFACE WINDS GUSTING INTO THE 20 TO 30 KT RANGE THIS
AFTERNOON AND TONIGHT. WITH FLOW REMAINING AT THE SURFACE...SHOULD
NOT REACH LLWS CRITERIA.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SUNDAY...
FORECAST CONFIDENCE: MEDIUM TO HIGH.
ALTERNATE SCENARIOS: TIMING OF MVFR MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EST 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY M H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY M H H H H H H H H H H H
PKB CONSISTENCY M H H H H H M M M H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 12Z SUNDAY...
IFR IN RAIN INTO SUNDAY. IFR POSSIBLE IN SNOW SHOWERS MONDAY NIGHT
INTO TUESDAY.
&&
.HYDROLOGY...
MODEL CONSENSUS SHOWS MAIN SWATH OF PRECIP JUST TO THE WEST OF THE
HSA. FOR THE WATCH AREA...EXPECT THE HEAVIEST RAINS TO OCCUR LATE
SATURDAY INTO SATURDAY NIGHT. 1 TO 2 INCHES ARE POSSIBLE WITH
LOCALLY HIGHER AMOUNTS. THE MAIN THREAT OF FLOODING IS FOR SMALL
STREAMS AND CREEKS...ESPECIALLY IN LOW LYING AND POOR DRAINAGE
AREAS. RISES ON THE MUSKINGUM ARE EXPECTED AS WELL. EVEN THOUGH THE
HEAVIEST RAINFALL IS EXPECTED TO FALL JUST OUTSIDE HSA...RUNOFF AND
STREAM FLOW WILL CONTINUE TO FLOW INTO THE WATCH AREA AND CAUSE
ELEVATED LEVELS ON STREAMS AND CREEKS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...FLOOD WATCH THROUGH SUNDAY MORNING FOR OHZ066-067.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/MZ/50
NEAR TERM...MZ
SHORT TERM...50
LONG TERM...RPY
AVIATION...MZ
HYDROLOGY...MZ
AREA FORECAST DISCUSSION
NWS MEDFORD OR
403 AM PST SAT DEC 21 2013
.DISCUSSION...
WHILE TEMPERATURES HAVE WARMED TO ABOVE FREEZING THIS MORNING AT
MID AND UPPER ELEVATIONS AND TO THE LEE OF THE CASCADES, MOST
INTERIOR VALLEY LOCATIONS HAVE BEEN HOVERING BETWEEN 30 AND 35
DEGREES. VERY LITTLE PRECIPITATION APPEARS TO HAVE FALLEN SINCE
LAST EVENING AWAY FROM THE COAST AND UMPQUA BASIN, BUT SUSPECT
WHAT HAS ALONG WITH WHAT FELL DURING THE EVENING HAS LED TO SOME
ICY SPOTS IN THE STEEPER, MORE SHELTERED VALLEY LOCATIONS. A
SPECIAL WEATHER STATEMENT HAS BEEN ISSUED FOR PORTIONS OF THE
INTERIOR WEST SIDE AND AREAS EAST OF THE CASCADES HIGHLIGHTING
WHERE THERE MAY BE A GLAZE OF ICE THIS MORNING.
OTHERWISE, IT SHOULD BE NOTED THAT WINDS HAVE BEEN HOWLING IN THE
HIGHER MOUNTAINS TO INCLUDE THE CRATER LAKE RIM, MOUNT SHASTA, AND
PROBABLY ANYWHERE ABOVE ABOUT 6000 FEET. GUSTS IN THESE LOCATIONS
OVERNIGHT RANGED FROM AROUND 40 MPH ON THE CRATER LAKE RIM TO 99
MPH AT GREY BUTTE AT 8000 FEET ON MOUNT SHASTA. WINDS APPEAR TO
HAVE EASED A BIT BELOW 8000 FEET IN THE LAST HOUR, BUT EXPECT THEM
TO REMAIN STRONG AT HIGHER ELEVATIONS THROUGH THIS EVENING.
PRECIPITATION TODAY THROUGH THE WEEKEND WILL CONTINUE TO WANE WITH
TIME. ONSHORE FLOW TODAY WILL BE FOCUSED ON THE WEST SIDE, AND
PRECIPITATION WILL BE MOSTLY ALONG AND NEAR THE COAST AND COASTAL
MOUNTAINS, UMPQUA BASIN, AND FOOTHILLS OF THE CASCADES NORTH OF
ABOUT HIGHWAY 140. I HAVE SCALED BACK PRECIPITATION PROBABILITIES
AND AMOUNTS SOME TO BE MORE IN ACCORDANCE WITH THE 3KM HRRR MODEL,
AS IT SEEMS TO BE DEPICT WHAT HAS OCCURRED OVERNIGHT WELL.
THIS AFTERNOON THROUGH NEXT WEEKEND THE ONLY EXPECTED TRAVEL PROBLEM
WILL BE VALLEY FOG AND FREEZING FOG. A WEAK FRONTAL SYSTEM WILL
DISSIPATE AS IT ARRIVES MONDAY INTO TUESDAY, WITH ANOTHER POSSIBLY
DOING THE SAME NEXT WEEKEND. THUS, OUR COOL AND DRY DECEMBER LOOKS
AS IF IT WILL CONTINUE AS SUCH. BTL
&&
.AVIATION...BASED ON THE 21/06Z TAF CYCLE.
A FEW WEAK DISTURBANCES WILL CONTINUE SCATTERED LIGHT PRECIPITATION
OVERNIGHT INTO EARLY SATURDAY MORNING. THE PROBABILITY OF
PRECIPITATION WILL BE HIGHEST OVER THE FOOTHILLS OF THE SOUTHERN
OREGON CASCADES AND THE CASCADES THEMSELVES. PRECIPITATION WILL FALL
MAINLY AS RAIN...INCLUDING AT THE TAF SITES. BUT THERE WILL BE LOCAL
FREEZING RAIN...MAINLY IN NARROW VALLEYS WHERE FREEZING AIR WILL
HAVE TROUBLE SCOURING OUT. THIS HAS CREATED MOUNTAIN OBSCURATIONS
WITH MAINLY MVFR VSBYS AND CIGS, BUT WITH ISOLATED IFR CONDITIONS
AND ALSO AREAS OF VFR CIGS. CONDITIONS WILL BEGIN TO IMPROVE AFTER
15Z SATURDAY MORNING WITH INCREASING COVERAGE OF VFR CIGS BUT WITH
AREAS OF MVFR CIGS PERSISTING THROUGH THE AFTERNOON...MAINLY IN
SOUTHWEST OREGON. DW
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...
- SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST SUNDAY
FOR PZZ350-356-370.
- SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST SUNDAY
FOR PZZ376.
$$
BTL/DW
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
549 AM CST SAT DEC 21 2013
.DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.
40
&&
.AVIATION...
THE FRONTAL BOUNDARY HAS MOVED EAST OF KCLL. THE RAP13 WAS DOING A
VERY GOOD JOB THIS MORNING. USED THE MODEL ALMOST EXCLUSIVELY FOR
KCLL AND INTERPOLATED ITS OUTPUT TO KUTS. THE MODEL WAVERS THE
FRONTAL BOUNDARY BACK NORTHWARD BY AROUND 15Z BEFORE PUSHING IT
SOUTHEASTWARD AGAIN AFTER 19Z. FURTHER TO THE SOUTH THE GUSTY
SOUTHERLY WINDS WILL PERSIST WITH THE FRONT NOT MAKING ITS WAY
THROUGH UNTIL ABOUT 19Z AT KCXO...AND THEN THE LATE AFTERNOON AT
THE METRO HOUSTON AIRPORTS SOUTHWARD TO THE COAST. IFR CONDITIONS
ARE MOST LIKELY FROM KIAH NORTHWARD. VFR IS EXPECTED TO DEVELOP
DURING THE AFTERNOON OVER KCLL AND KUTS...BUT NOT UNTIL BETWEEN
23Z AND 03Z ELSEWHERE.
40
&&
.PREV DISCUSSION... /ISSUED 436 AM CST SAT DEC 21 2013/
UPDATE...
A QUICK UPDATE TO ADJUST FOR TEMPS OVER THE NORTHWEST.
DISCUSSION...
THE RAP IS HANDLING TEMPS MUCH BETTER THAN ALL OTHER MODELS. FRONT
WENT THROUGH CLL AND RWV WITH TEMPS NOW IN THE LOWER 40S. HAVE
ADJUSTED HOURLY TEMP GRIDS TO REFLECT COOLER START OVER THE
NORTHWEST. 43
PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 21 2013/
DISCUSSION...
SHOWERS AND THUNDERSTORMS ARE INCREASING IN COVERAGE AND INTENSITY
THIS MORNING AS A STRONG UPPER LEVEL LOW OVER SOUTHERN NEW MEXICO
MOVES NE TOWARD CENTRAL OK. AT 3 AM...A STRONG SURFACE COLD FRONT
EXTENDED FROM NEAR LONGVIEW TO PALASTINE TO AUSTIN. TEMPS ARE 36
AT WACO AND 72 AT COLLEGE STATION. THE COMBINATION OF THE TROUGH
AND FRONT WILL SET THE STAGE FOR NUMEROUS SHRA/TSRA TODAY. SPC HAS
ALL OF SE TX OUTLOOKED IN SLIGHT RISK...BUT THE RISK IS
CONDITIONAL ON WHETHER CAPPING ERODES OR STAYS IN PLACE. SHEAR
VALUES ARE EXTREMELY HIGH BUT OTHER SEVERE WEATHER PARAMETERS ARE
FAIRLY TAME WITH CAPE VALUES LESS THAN 1000 J/KG. UPPER LEVEL
WINDS LOOK FAVORABLE AS SE TX WILL LIE IN 140 KT RRQ AROUND 18Z.
GFS FCST SOUNDING DATA IS CONSIDERABLY DRIER TODAY THAN YESTERDAY
AND ACTUALLY MATCHES UP WELL WITH THE 00Z CRP SOUNDING SO HAVE
SOME CONCERN THAT THE DRIER GFS SOLN MAY VERIFY. FCST SOUNDINGS
SHOW THE CAPPING INVERSION ERODING BETWEEN 12-15Z. FCST SOUNDINGS
ALSO SHOW A A FAIRLY DEEP DRY LAYER BETWEEN 850-700 MB WHICH NEVER
FULLY SATURATES. STILL...ITS HARD TO IGNORE THE NEGATIVE TILT TO
THE UPPER TROUGH...SFC BOUNDARY AND JET DYNAMICS. HAVE LEANED
TOWARD A BLEND OF THE HI- RES ARW...RAP...NAM 12 AND ECWMF FOR
TODAY. LOOKS LIKE SCT ACTIVITY WILL EVENTUALLY FORM A LINE OF
STORMS SOMEWHERE OVER THE CENTRAL PORTION OF THE CWA BETWEEN
15-18Z. THE LINE OF STORMS WILL THEN PUSH THROUGH THE REST OF THE
CWA BETWEEN 18-20Z. CAPPING IS LESS TOWARD THE NORTH AND EASTERN
PORTIONS OF THE CWA SO FEEL BEST THREAT FOR SEVERE WEATHER WILL BE
NORTHEAST OF A COLLEGE STATION TO HOUSTON TO GALVESTON LINE. THE
PRIMARY SEVERE WEATHER HAZARD WILL WILL BE DAMAGING WINDS AND
ISOLATED TORNADOES. IF CAPPING HOLDS...THE RISK FOR SEVERE WEATHER
WILL GREATLY DIMINISH. IT WILL BE INTERESTING TO SEE THE 12Z
SOUNDINGS.
A SECONDARY SURGE OF COLDER AIR WILL ARRIVE ON SUNDAY ALONG WITH
SOME MID LEVEL CLOUDINESS. HIGH TEMPS ON SUNDAY WILL BE ABOUT 20
DEGREES COOLER THAN TODAY. IT WILL STAY COOL FOR MUCH OF NEXT
WEEK AS THE UPPER FLOW REMAINS SOMEWHAT AMPLIFIED. ANOTHER S/WV
WILL DIG SSE ON WEDNESDAY AND THIS FEATURE WILL BRING SOME RAIN
BACK TO SOUTHEAST TEXAS LATE IN THE DAY AND OVERNIGHT. THE
CANADIAN IS THE MOST AGGRESSIVE WITH RAIN AND THE GFS WAS THE
DRIEST. THE ECMWF WAS A NICE COMPROMISE. ANOTHER FRONT IS EXPECTED
NEXT SATURDAY WHICH WILL REINFORCE THE ONGOING COOL CONDITIONS. 43
MARINE...
SEA FOG CONTINUED TO AFFECT GALVESTON BAY EARLY THIS MORNING. THE
FOG SHOULD LIFT LATER THIS MORNING AS SOUTHWESTERLY WINDS DEVELOP.
THE COOLER WATERS OF THE BAYS AND NEARSHORE GULF WATERS WILL KEEP
THE WIND SPEEDS DOWN THIS MORNING AS WELL. ADVISORY CONDITIONS WILL
PERSIST OVER THE OFFSHORE WATERS.
EXPECT WINDS WILL PICK UP OVER THE BAYS AND NEARSHORE WATERS TONIGHT
AS THE FRONT MOVES OFF THE COAST. OTHERWISE...ANOTHER BOUT OF
ADVISORY CONDITIONS ARE EXPECTED SUNDAY NIGHT AND MONDAY WITH THE
PASSAGE OF A STRONGER FRONT. THE MODELS THEN RETURN ONSHORE WINDS
BY LATE TUESDAY.
40
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 60 44 56 30 52 / 80 10 10 0 0
HOUSTON (IAH) 73 50 64 34 54 / 80 20 10 0 0
GALVESTON (GLS) 62 57 65 42 52 / 80 20 10 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE
FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO
FREEPORT 20 TO 60 NM.
DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR THE
FOLLOWING ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO
FREEPORT OUT 20 NM.
&&
$$
DISCUSSION...43
AVIATION/MARINE...40
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
436 AM CST SAT DEC 21 2013
.UPDATE...
A QUICK UPDATE TO ADJUST FOR TEMPS OVER THE NORTHWEST.
&&
.DISCUSSION...
THE RAP IS HANDLING TEMPS MUCH BETTER THAN ALL OTHER MODELS. FRONT
WENT THROUGH CLL AND RWV WITH TEMPS NOW IN THE LOWER 40S. HAVE
ADJUSTED HOURLY TEMP GRIDS TO REFLECT COOLER START OVER THE
NORTHWEST. 43
&&
.PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 21 2013/
DISCUSSION...
SHOWERS AND THUNDERSTORMS ARE INCREASING IN COVERAGE AND INTENSITY
THIS MORNING AS A STRONG UPPER LEVEL LOW OVER SOUTHERN NEW MEXICO
MOVES NE TOWARD CENTRAL OK. AT 3 AM...A STRONG SURFACE COLD FRONT
EXTENDED FROM NEAR LONGVIEW TO PALASTINE TO AUSTIN. TEMPS ARE 36
AT WACO AND 72 AT COLLEGE STATION. THE COMBINATION OF THE TROUGH
AND FRONT WILL SET THE STAGE FOR NUMEROUS SHRA/TSRA TODAY. SPC HAS
ALL OF SE TX OUTLOOKED IN SLIGHT RISK...BUT THE RISK IS
CONDITIONAL ON WHETHER CAPPING ERODES OR STAYS IN PLACE. SHEAR
VALUES ARE EXTREMELY HIGH BUT OTHER SEVERE WEATHER PARAMETERS ARE
FAIRLY TAME WITH CAPE VALUES LESS THAN 1000 J/KG. UPPER LEVEL
WINDS LOOK FAVORABLE AS SE TX WILL LIE IN 140 KT RRQ AROUND 18Z.
GFS FCST SOUNDING DATA IS CONSIDERABLY DRIER TODAY THAN YESTERDAY
AND ACTUALLY MATCHES UP WELL WITH THE 00Z CRP SOUNDING SO HAVE
SOME CONCERN THAT THE DRIER GFS SOLN MAY VERIFY. FCST SOUNDINGS
SHOW THE CAPPING INVERSION ERODING BETWEEN 12-15Z. FCST SOUNDINGS
ALSO SHOW A A FAIRLY DEEP DRY LAYER BETWEEN 850-700 MB WHICH NEVER
FULLY SATURATES. STILL...ITS HARD TO IGNORE THE NEGATIVE TILT TO
THE UPPER TROUGH...SFC BOUNDARY AND JET DYNAMICS. HAVE LEANED
TOWARD A BLEND OF THE HI- RES ARW...RAP...NAM 12 AND ECWMF FOR
TODAY. LOOKS LIKE SCT ACTIVITY WILL EVENTUALLY FORM A LINE OF
STORMS SOMEWHERE OVER THE CENTRAL PORTION OF THE CWA BETWEEN
15-18Z. THE LINE OF STORMS WILL THEN PUSH THROUGH THE REST OF THE
CWA BETWEEN 18-20Z. CAPPING IS LESS TOWARD THE NORTH AND EASTERN
PORTIONS OF THE CWA SO FEEL BEST THREAT FOR SEVERE WEATHER WILL BE
NORTHEAST OF A COLLEGE STATION TO HOUSTON TO GALVESTON LINE. THE
PRIMARY SEVERE WEATHER HAZARD WILL WILL BE DAMAGING WINDS AND
ISOLATED TORNADOES. IF CAPPING HOLDS...THE RISK FOR SEVERE WEATHER
WILL GREATLY DIMINISH. IT WILL BE INTERESTING TO SEE THE 12Z
SOUNDINGS.
A SECONDARY SURGE OF COLDER AIR WILL ARRIVE ON SUNDAY ALONG WITH
SOME MID LEVEL CLOUDINESS. HIGH TEMPS ON SUNDAY WILL BE ABOUT 20
DEGREES COOLER THAN TODAY. IT WILL STAY COOL FOR MUCH OF NEXT
WEEK AS THE UPPER FLOW REMAINS SOMEWHAT AMPLIFIED. ANOTHER S/WV
WILL DIG SSE ON WEDNESDAY AND THIS FEATURE WILL BRING SOME RAIN
BACK TO SOUTHEAST TEXAS LATE IN THE DAY AND OVERNIGHT. THE
CANADIAN IS THE MOST AGGRESSIVE WITH RAIN AND THE GFS WAS THE
DRIEST. THE ECMWF WAS A NICE COMPROMISE. ANOTHER FRONT IS EXPECTED
NEXT SATURDAY WHICH WILL REINFORCE THE ONGOING COOL CONDITIONS. 43
MARINE...
SEA FOG CONTINUED TO AFFECT GALVESTON BAY EARLY THIS MORNING. THE
FOG SHOULD LIFT LATER THIS MORNING AS SOUTHWESTERLY WINDS DEVELOP.
THE COOLER WATERS OF THE BAYS AND NEARSHORE GULF WATERS WILL KEEP
THE WIND SPEEDS DOWN THIS MORNING AS WELL. ADVISORY CONDITIONS WILL
PERSIST OVER THE OFFSHORE WATERS.
EXPECT WINDS WILL PICK UP OVER THE BAYS AND NEARSHORE WATERS TONIGHT
AS THE FRONT MOVES OFF THE COAST. OTHERWISE...ANOTHER BOUT OF
ADVISORY CONDITIONS ARE EXPECTED SUNDAY NIGHT AND MONDAY WITH THE
PASSAGE OF A STRONGER FRONT. THE MODELS THEN RETURN ONSHORE WINDS
BY LATE TUESDAY.
40
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 66 44 56 30 52 / 80 10 10 0 0
HOUSTON (IAH) 73 50 64 34 54 / 80 20 10 0 0
GALVESTON (GLS) 62 57 65 42 52 / 60 20 10 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE
FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO
FREEPORT 20 TO 60 NM.
DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR THE
FOLLOWING ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO
FREEPORT OUT 20 NM.
&&
$$
DISCUSSION...43
AREA FORECAST DISCUSSION
NWS SPOKANE WA
445 AM PST Sat Dec 21 2013
.SYNOPSIS...
A storm system will continue to shift out the Inland Northwest
today and tonight...however moist northwest flow will persist.
This will keep the threat of light snow or freezing drizzle over
the region through the weekend. The best chances for precipitation
will occur near the Cascades and over southeast Washington and the
central Idaho Panhandle. Another storm will move into the area on
Monday, but with milder valley temperatures and less
precipitation. Drier weather is expected toward the middle to
latter part of next week, including Christmas Day.
&&
.DISCUSSION...
Today and Tonight...Yesterdays strong shortwave trough and
associated warm front has generally shifted south and east of the
region while the strong offshore ridge remains in place. This will
keep northwest flow over the area through the day. Satellite
imagery not depicting any shortwave disturbances upstream from us
at the moment...however low level moisture remains plentiful per
the latest fog product. Most of this moisture was present as an
extensive blanket of stratus covering much of the forecast area.
There was also a mid-level cloud deck covering the southern Idaho
Panhandle and SE Washington associated with weak-moderate
isentropic ascent. Radar continued to show very light returns in
these areas while nearby observations were detecting occasional
light precipitation in the form of light snow...and perhaps some
freezing drizzle. The HRRR was handling things quite well...and if
it performance remains consistent...this precipitation will wane
through the morning as it dives south of the forecast area.
Consequently we will continue to chip away at the winter
highlights. We will remove the Palouse for now...with the others
soon to follow. The precipitation should ease out of the Camas
Prairie last...and this highlight may need to be extended a couple
hours.
For tonight...the moist northwest flow continue and a weak
shortwave is expected to drop over the northern Cascades this
evening and into the Idaho Panhandle later tonight. The isentropic
ascent will strengthen ahead of the feature and should produce
another round of precipitation. This time...the amount of
atmospheric moisture will pale compared to yesterdays event while
the dendritic layer saturation and lifting looks unimpressive.
Even so...the Cascades will see good chances of precipitation
overnight...with an increasing trend for SE Washington and the
central Panhandle overnight. Most of the precipitation will fall
as light snow...however without a fully saturated dendritic
layer...some drizzle or freezing drizzle could also occur. fx
Sunday and Sunday Night: Moisture continues to move over the top
of the ridge to our west for Sunday before another system gets
set to move in Sunday Night into Monday. From current models most
of the moisture looks to get hung up in the Cascades leaving much
of the Basin essentially dry. It is not until the higher terrain
further downstream in the flow pattern that the chance for
precipitation once again returns. Given the NW flow pattern this
would allow for the Blues and Central Panhandle Mtns to see the
best chance for precip. As we move into Sunday Night the pattern
becomes more zonal as the next approaching system flattens the
ridge putting the Cascades and Panhandle Mtns as the most
influential terrain for added topographic forcing and therefore the
best chance for precipitation. Isentropic forcing looks weak to
moderate so the additional forcing will be necessary.
Snow levels will be on the rise throughout the period and can be
attributed to warmer air pushing into the region from the SSW. By
the time the best moisture arrives Sunday Night into Monday, snow
levels will be above most valley locations leading to a valley rain
mountain snow event. The one exception would be the far northern
valleys which could hold onto cold air long enough to see some snow
from the system. Temperatures look to be above normal for most as
the warm southerly air pushes into the area. /Fliehman
Monday through Friday: Now that we have some snow on the ground,
can we keep it around for a White Christmas? Monday`s weather is
going to make it tough. A short wave currently south of the
Aleutians is forecast to move through the eastern Pacific ridge
and into the Pac NW by Monday. All computer models agree that this
will set up a strong southwesterly low-level flow, and will push
the cold air out of the Inland NW. This will raise snow levels
above the valley floors, except for near the Canadian border.
Thus, this system will bring valley rain instead of snow. Not a
lot mind you. But the real snow-eater is the warm wind with dew
points above freezing. Winds will increase on Monday afternoon and
continue through the evening as the cold front passes through.
After this, drier air will move into the region and snow levels
will once again drop to the valley floors. But the high pressure
ridge re-develops, closing the door to any more Pacific storms.
Typically such a ridge would lead to the development of fog and
low clouds. Models agree, but they would suggest that there will
be enough flow the push the low clouds around instead of filling
in the entire Basin.
The only other weather feature of note will be some mid-level
moisture spilling over the ridge in the 2nd half of the week.
There`s no lifting mechanism, so this should just be confined to a
few snow showers over the northern mountains. RJ
&&
.AVIATION...
12Z TAFS: The threat of widespread precipitation has ended over the
area for the day...however widespread low clouds remain entrenched
over all sites except for MWH. The cloud bases will likely range
from 004 to 014 through most of the forecast period so look for
MVFR/IFR conditions mainly attributed to cigs. The worst conditions
will likely impact PUW as light west winds continue to reinforce the
low cigs and fog. All sites should see some subtle improvements
during the afternoon...but with fairly strong inversions in place
and light winds through the mixed layer this is far from certain.
Another disturbance moves into the region after 00z...which should
expand the low cloud blanket as well as deliver a small chance of
-shsn or -fzdz mainly for PUW and LWS. fx
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 29 22 33 28 38 26 / 0 20 20 50 70 30
Coeur d`Alene 30 24 35 29 39 29 / 0 20 30 50 80 60
Pullman 32 27 37 31 41 27 / 10 40 30 30 70 50
Lewiston 34 30 40 32 41 29 / 20 40 30 20 30 50
Colville 28 21 31 26 36 25 / 0 10 20 50 70 20
Sandpoint 29 22 32 27 37 27 / 0 30 30 50 80 70
Kellogg 30 26 34 31 38 31 / 20 50 40 50 90 70
Moses Lake 31 19 34 24 42 21 / 0 0 20 10 20 0
Wenatchee 33 24 35 27 41 25 / 10 0 20 20 10 10
Omak 26 19 31 23 35 21 / 0 10 20 20 20 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 5 AM PST early this morning for
Central Panhandle Mountains-Lewis and Southern Nez Perce
Counties.
Winter Weather Advisory until 5 AM PST early this morning for
Lewiston Area.
WA...Winter Storm Warning until 5 AM PST early this morning for
Northeast Blue Mountains.
Winter Weather Advisory until 5 AM PST early this morning for
Lower Garfield and Asotin Counties.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
257 AM PST Sat Dec 21 2013
.SYNOPSIS...
A storm system will continue to shift out the Inland Northwest
today and tonight...however moist northwest flow will persist.
This will keep the threat of light snow or freezing drizzle over
the region through the weekend. The best chances for precipitation
will occur near the Cascades and over southeast Washington and the
central Idaho Panhandle. Another storm will move into the area on
Monday, but with milder valley temperatures and less
precipitation. Drier weather is expected toward the middle to
latter part of next week, including Christmas Day.
&&
.DISCUSSION...
Today and Tonight...Yesterdays strong shortwave trough and
associated warm front has generally shifted south and east of the
region while the strong offshore ridge remains in place. This will
keep northwest flow over the area through the day. Satellite
imagery not depicting any shortwave disturbances upstream from us
at the moment...however low level moisture remains plentiful per
the latest fog product. Most of this moisture was present as an
extensive blanket of stratus covering much of the forecast area.
There was also a mid-level cloud deck covering the southern Idaho
Panhandle and SE Washington associated with weak-moderate
isentropic ascent. Radar continued to show very light returns in
these areas while nearby observations were detecting occasional
light precipitation in the form of light snow...and perhaps some
freezing drizzle. The HRRR was handling things quite well...and if
it performance remains consistent...this precipitation will wane
through the morning as it dives south of the forecast area.
Consequently we will continue to chip away at the winter
highlights. We will remove the Palouse for now...with the others
soon to follow. The precipitation should ease out of the Camas
Prairie last...and this highlight may need to be extended a couple
hours.
For tonight...the moist northwest flow continue and a weak
shortwave is expected to drop over the northern Cascades this
evening and into the Idaho Panhandle later tonight. The isentropic
ascent will strengthen ahead of the feature and should produce
another round of precipitation. This time...the amount of
atmospheric moisture will pale compared to yesterdays event while
the dendritic layer saturation and lifting looks unimpressive.
Even so...the Cascades will see good chances of precipitation
overnight...with an increasing trend for SE Washington and the
central Panhandle overnight. Most of the precipitation will fall
as light snow...however without a fully saturated dendritic
layer...some drizzle or freezing drizzle could also occur. fx
Sunday and Sunday Night: Moisture continues to move over the top
of the ridge to our west for Sunday before another system gets
set to move in Sunday Night into Monday. From current models most
of the moisture looks to get hung up in the Cascades leaving much
of the Basin essentially dry. It is not until the higher terrain
further downstream in the flow pattern that the chance for
precipitation once again returns. Given the NW flow pattern this
would allow for the Blues and Central Panhandle Mtns to see the
best chance for precip. As we move into Sunday Night the pattern
becomes more zonal as the next approaching system flattens the
ridge putting the Cascades and Panhandle Mtns as the most
influential terrain for added topographic forcing and therefore
the best chance for precipitation. Isentropic forcing looks weak to moderate
so the additional forcing will be necessary.
Snow levels will be on the rise throughout the period and can be
attributed to warmer air pushing into the region from the SSW. By
the time the best moisture arrives Sunday Night into Monday, snow levels
will be above most valley locations leading to a valley rain
mountain snow event. The one exception would be the far northern
valleys which could hold onto cold air long enough to see some
snow from the system. Temperatures look to be above normal for
most as the warm southerly air pushes into the area. /Fliehman
Monday through Friday: Now that we have some snow on the ground,
can we keep it around for a White Christmas? Monday`s weather is
going to make it tough. A short wave currently south of the
Aleutians is forecast to move through the eastern Pacific ridge
and into the Pac NW by Monday. All computer models agree that this
will set up a strong southwesterly low-level flow, and will push
the cold air out of the Inland NW. This will raise snow levels
above the valley floors, except for near the Canadian border.
Thus, this system will bring valley rain instead of snow. Not a
lot mind you. But the real snow-eater is the warm wind with dew
points above freezing. Winds will increase on Monday afternoon and
continue through the evening as the cold front passes through.
After this, drier air will move into the region and snow levels
will once again drop to the valley floors. But the high pressure
ridge re-develops, closing the door to any more Pacific storms.
Typically such a ridge would lead to the development of fog and
low clouds. Models agree, but they would suggest that there will
be enough flow the push the low clouds around instead of filling
in the entire Basin.
The only other weather feature of note will be some mid-level
moisture spilling over the ridge in the 2nd half of the week.
There`s no lifting mechanism, so this should just be confined to a
few snow showers over the northern mountains. RJ
&&
.AVIATION...
06Z TAFS: A storm system will continue to move through southeast
WA and central Idaho tonight into Saturday morning. This passing
feature and northwest flow will keep some light snow and/or
freezing rain in the region of the KLWS/KPUW TAFs through 10-12Z.
Some patchy freezing drizzle is also possible about the KGEG to
KCOE corridor. Otherwise look for some low clouds, with IFR/LIFR
conditions, including some mist/fog with visibilities occasionally
under 2 miles. Some of these are expected to expand toward KEAT
through the night too. Conditions are then expected to gradually
improve through the day Saturday, with some brief VFR/MVFR
conditions in the mid-afternoon, before conditions degrade again
after 00-03Z. Additional light snow will be possible Saturday
night, though the better chances will hold off until after 06Z
Sunday. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 29 22 33 28 38 26 / 0 20 20 50 70 30
Coeur d`Alene 30 24 35 29 39 29 / 0 20 30 50 80 60
Pullman 32 27 37 31 41 27 / 10 40 30 30 70 50
Lewiston 34 30 40 32 41 29 / 20 40 30 20 30 50
Colville 28 21 31 26 36 25 / 0 10 20 50 70 20
Sandpoint 29 22 32 27 37 27 / 0 30 30 50 80 70
Kellogg 30 26 34 31 38 31 / 20 50 40 50 90 70
Moses Lake 31 19 34 24 42 21 / 0 0 20 10 20 0
Wenatchee 33 24 35 27 41 25 / 10 0 20 20 10 10
Omak 26 19 31 23 35 21 / 0 10 20 20 20 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 5 AM PST early this morning for
Central Panhandle Mountains-Lewis and Southern Nez Perce
Counties.
Winter Weather Advisory until 5 AM PST early this morning for
Lewiston Area.
WA...Winter Storm Warning until 5 AM PST early this morning for
Northeast Blue Mountains.
Winter Weather Advisory until 5 AM PST early this morning for
Lower Garfield and Asotin Counties.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
524 AM CST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CST SAT DEC 21 2013
CONCENTRATING ON REFINING THE WINTER STORM DETAILS AND IMPACTS IN
THE FORECAST SUITE. IN GENERAL...THERE HAVE BEEN MINOR CHANGES TO
THE FORECAST FOR THIS STORM...AND IT STILL LOOKS ON TRACK.
THIS SYSTEM IS WHY MANY METEOROLOGISTS WENT INTO WEATHER. THE
POWER RIGHT NOW FROM THIS SYSTEM IN THE SOUTHERN U.S. IS
REMARKABLE. GOES WATER VAPOR CLEARLY SHOWING THE STRONG TROUGH
OVER SRN NEW MEXICO WITH STRONG QVECTOR CONVERGENCE AND FORCING
OVER WESTERN TEXAS /GREAT TRANSVERSE WAVES ON IR IMAGERY/. SURFACE
PRESSURES ARE FALLING IN ARKANSAS ABOUT 1MB/HR...AND THE LOW-LEVEL
JET IS INCREASING INTO A FRONTAL ZONE DEFINED BY 34F TO 72F ACROSS
NRN AR...AND CONVECTION WITH C-G LIGHTNING. DEWPOINTS IN THE WARM
SECTOR ARE IN THE LOWER 70S ILLUSTRATING THE AMOUNT OF MOISTURE
DRAWING INTO THIS SYSTEM.
THIS STORM HAS ALL THE DYNAMICS FOR A MAJOR PRECIPITATION
PRODUCER...STRONG AND COMPACT QVECTOR CONVERGENCE/DIVERGENCE
DIPOLE...UPPER LEVEL JET ENTRANCE REGION DIVERGENCE ALOFT /JET MAX
OVER SRN CANADA OF 180KTS FORECAST/...STRONG FRONTOGENETIC FORCING
AT 600-700MB /GREAT FOR SNOW PRODUCTION/. SO...THE QUESTION IS
WHERE WILL THE SNOW BAND LAY DOWN...WITHIN A COUNTY...AND TRYING
TO UNDERSTAND WHY THE MODELS ARE STILL DIFFERENT.
SINCE 20.12Z...THE NAM HAS REALLY CHANGED ITS TUNE TO A WET AND WEST
AND MORE IN-LINE SOLUTION WITH THE GFS/EC/CANADIAN...AND HAS BEEN
CONSISTENT WITH ITS OUTCOMES IN THE LAST 3 RUNS. THE HIGHEST
PRECIPITATION BAND IS CONSISTENT WITH THE 20.12 ECMWF AND LATEST
CANADIAN/GFS RUNS...ROUGHLY FROM KDBQ-KDLL AND SOUTHEAST. THE
21.12Z ECMWF HAS SHIFTED A BIT EAST NOW. OVERALL...THE ECMWF SEEMS
TO HAVE THE BEST 500MB DEPICTION INDICATING A STRONG NEARLY CLOSED
LOW SHIFTING NORTHEAST...WHILE THE 21.00Z GFS VORTICITY IS
DISORGANIZED AND CHANNELED...AND THE GFS SURFACE LOW FURTHEST
EAST. WPC MODEL GUIDANCE DISCUSSION PREFERRED AN ECMWF SOLUTION OR
NON-NCEP ENSEMBLE. BOTTOM LINE IS THEY ARE ALL VERY REASONABLE ON
QPF/SNOW AMOUNTS EXCEPT POSSIBLY THE NAM THAT SEEMS TO SPREAD TOO
MUCH PRECIPITATION NORTHWEST...SUGGESTING IMPACTS FURTHER WEST
INTO MN/IA...A WIDE ADVISORY SNOW AREA. WHILE THIS SOLUTION CANNOT
BE DISCOUNTED...THE NORTHERN STREAM INFLUENCE/DEFORMATION SHOULD
LIMITED THE WESTWARD EXTENT....AND THE UPPER JET DIVERGENCE SEEMS
TO SUPPORT A MORE WI/IL SOLUTION FOR THE BEST LIFT /EAST/.
SNOW FORECAST REMAINS CONSISTENT...BUT HAVE MADE A SLIGHT TWEAK
WEST...MAYBE ONE-HALF A COUNTY. THE WARNING IS WELL PLACED...BUT
HAVE DECIDED TO INCLUDE JUNEAU AND ADAMS COUNTY IN CENTRAL WI.
ALSO HAVE ADDED FAYETTE COUNTY TO THE WARNING AFTER COLLABORATION
WITH DMX. HAVE CHANGED THE REMAINING WATCH COUNTIES TO AN ADVISORY
AND BASED ON THE 3 INCH SNOW TOTAL LINE...BUILT A FEW OTHER
COUNTIES INTO THE ADVISORY WESTWARD.
TIMING...
LATEST RUNS OF THE RAP INDICATE THE POSSIBILITY OF PRECIPITATION
TO THE IL/WI BORDER BY 6 PM TONIGHT. THIS IS A BIT FASTER TREND
THAN THE OTHER MODELS WHICH BEGIN SNOW AROUND 8-9PM IN THE SOUTH.
EVEN THOUGH CONSENSUS IS FOR ONSET IN THE SOUTH AT 8-9 PM HAVE
LEFT THAT START TIME 6 PM FOR NOW. THAT CAN BE ADJUSTED IF NEEDED.
HOWEVER...HAVE ADJUSTED START TIME IN CENTRAL WI TO 03Z/9PM FOR
THE WARNING...BASICALLY THE I-90 CORRIDOR. THE HEAVIEST SNOW WILL
FALL FROM ABOUT 3 AM TO 9 AM.
IMPACTS...
BECAUSE THIS STORM HAS SHORTER DURATION...WARNING SNOW
AMOUNTS WILL NOT BE UNUSUAL IN THE FORECAST AREA WITH 6 TO 8
INCHES EXPECTED AND 2 TO 5 IN THE ADVISORY. WINDS WILL BE
STRONGEST IN SERN MN INTO NERN IA...15 TO 25 MPH. THIS LEADS TO
THE UPGRADE TO WARNING IN FAYETTE AS A BIT MORE BLOWING IS
EXPECTED THERE WITH 4-5 INCHES OF SNOW.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CST SAT DEC 21 2013
SNOW SLOWLY DIMINISHES TO FLURRIES OR VERY LIGHT ACCUMULATING SNOW
SUNDAY AFTERNOON. HOWEVER...THE NORTHERN STREAM DAKOTAS SHORTWAVE
TROUGH WILL BE MOVING IN WITH THE SURGE OF ARCTIC AIR SUNDAY
NIGHT. THIS FORCING AND COLD ADVECTION WILL PROVIDE SOME
INSTABILITY AND LIFT FOR AN EXTENSION OF LIGHTLY ACCUMULATING
SNOW. SUNDAY NIGHT AND MONDAY MORNING COULD BRING ANOTHER 1-2
INCHES OF FLUFFY SNOW...WITH THE 2 INCH AMOUNTS NEAR AND NORTHEAST
OF I-94. THIS IS A LARGER CHANGE IN THE FORECAST.
AN ACTIVE PATTERN CONTINUES THROUGH THE WEEK WITH WARM ADVECTION
SNOWFALL POSSIBLE CHRISTMAS EVE AND ANOTHER VIGOROUS TROUGH
POSSIBLY THURSDAY WITH ANOTHER COLD AIR SURGE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 524 AM CST SAT DEC 21 2013
IFR/MVFR CLOUD COVER WILL CONTINUE THROUGH TODAY. ATTENTION THEN
TURNS TO A POTENT LOW PRESSURE SYSTEM LIFTING OUT OF THE SOUTHERN
PLAINS INTO THE GREAT LAKES REGION TONIGHT THROUGH SUNDAY. SNOW IS
EXPECTED TO SPREAD INTO NORTHEAST IA/SOUTHERN WI THIS EVENING AND
THEN INTO THE KLSE/KRST TAF SITES AFTER 07Z/09Z RESPECTIVELY. DUE
TO THE TRACK OF THE STORM SYSTEM...KLSE LOOKS TO BE IMPACTED BY
MODERATE SNOWFALL SNOW AT TIMES AFTER 10Z WITH TEMPORARY LIFR
VSBY/CIG CONDITIONS THROUGH MID-SUNDAY MORNING. LIGHTER SNOWFALL
WILL BE SEEN AT KRST AS A RESULT OF BEING FARTHER NORTHWEST OF
THE TRACK OF THE LOW...BUT REMAINING IN IFR CONDITIONS.
RIGHT NOW...IT APPEARS AROUND 3 INCHES OF SNOWFALL IS LIKELY
TONIGHT THROUGH SUNDAY AT KLSE WITH 1 TO 1.5 INCHES LIKELY AT
KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR WIZ053.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR WIZ054-055-061.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST
SUNDAY FOR WIZ034-041-042.
WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY
FOR WIZ043-044.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR MNZ096.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR IAZ010-011-019.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR IAZ029-030.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...DAS
AREA FORECAST DISCUSSION
NWS PUEBLO CO
250 PM MST SAT DEC 21 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 250 PM MST SAT DEC 21 2013
UPPER LOW IS LIFTING OUT INTO WESTERN OK WHILE TRAILING ENERGY IS
DROPPING ACROSS THE FORECAST AREA IN NW FLOW ALOFT. PRECIPITATION HAS
BEEN SLOW TO GET GOING ACROSS THE FORECAST AREA...THOUGH WEB CAMS
AND SURFACE OBS ALONG THE CONTDVD HAVE BEEN REPORTING SOME SNOW
THROUGH THE DAY. INITIALLY HEAVIEST SNOW AND BEST LIFT WILL BE OUT
ACROSS THE FAR SOUTHEAST CORNER OF THE FORECAST AREA WHERE WRAP
AROUND PRECIPITATION CONTINUES ACROSS BACA COUNTY. STILL SOME
VARIABILITY IN THE SHORT RANGE MODELS FOR SNOW AMOUNTS OUT THAT
WAY...BUT AN INCH OR TWO WOULD`T BE OUT OF THE QUESTION ACROSS
SOUTHEAST PORTIONS OF BACA COUNTY. MEANWHILE...SHOULD START TO SEE
LIGHT SNOW RAMP UP ACROSS THE EASTERN MOUNTAINS AND ADJACENT PLAINS
BY 4 PM...WHICH WILL SPREAD SOUTH AND EAST THROUGH THE EVENING.
NAM12 AND HRRR SEEM TO BE BACKING OFF ON SNOWFALL AMOUNTS WITH EACH
RUN...WITH NAM12 NOW SHOWING AROUND 2-4 INCHES FOR THE SE MTS. HAVE
KEPT SNOW AMOUNTS IN THE 2-6 INCH RANGE AS SUSPECT THERE WILL BE POCKETS OF
HEAVIER AMOUNTS...HOWEVER WITHOUT A PERSISTENT DEEP NE UPSLOPE
FLOW...THINK THESE HEAVIER AMOUNTS WILL BE MORE LOCALIZED. THUS
ADVISORIES DO NOT SEEM WARRANTED AT THIS POINT. LIGHT SNOW WILL
WIND DOWN TOWARDS TOMORROW MORNING WITH PARTIAL CLEARING ACROSS
WESTERN AND NORTHERN PORTIONS OF THE AREA TOWARDS DAWN. THIS OPENS
UP THE POSSIBILITY FOR ANOTHER ROUND OF GROUND FOG AT KALS EARLY
SUNDAY MORNING...AND HAVE INTRODUCED THIS TO THE GRIDS.
QUIET WEATHER FOR SUNDAY...THOUGH NORTHWEST FLOW MAY KEEP SOME
SCATTERED OROGRAPHIC SNOW SHOWERS CONTINUING ACROSS THE CENTRAL MTS.
TEMPERATURES TOMORROW MAY END UP SIMILAR TO THOSE OF TODAY...PERHAPS
A LITTLE WARMER ACROSS PORTIONS OF THE PLAINS AND A TAD COOLER
ACROSS THE MTS WHERE H7 TEMPS WILL BE A LITTLE COOLER BEHIND THIS
EVENINGS SYSTEM. -KT
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 250 PM MST SAT DEC 21 2013
SUNDAY NIGHT-MONDAY...STRONG NORTH TO NORTHWEST FLOW ALOFT ACROSS
THE REGION SUNDAY NIGHT SLOWLY MODERATES THROUGH THE DAY MONDAY...AS
A BROAD UPPER TROUGH AND ASSOCIATED 120KT JET CORE ACROSS THE NORTHERN
ROCKIES TRANSLATES OUT ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS.
NORTHWEST FLOW ALOFT BEHIND THE SYSTEM LOOKS TO KEEP GENERALLY LIGHT
SNOWFALL IN PLACE ACROSS THE CENTRAL MTS THROUGH EARLY MONDAY
MORNING...WITH ACCUMULATIONS OF A FEW INCHES POSSIBLE ESPECIALLY
NORTH OF COTTONWOOD PASS. PASSING SYSTEM STAYS TOO FAR NORTH AND
EAST TO BRING PRECIPITATION TO THE REST OF SOUTH CENTRAL AND
SOUTHEAST COLORADO...THOUGH DOES SEND A WEAK COLD FRONT ACROSS
THE FAR EASTERN PLAINS EARLY MONDAY MORNING...KEEPING THE COOLEST
TEMPERATURES OUT NEAR THE KANSAS BORDER.
MONDAY NIGHT-CHRISTMAS DAY...LATEST MODELS CONTINUE TO DOWNPLAY
SNOWFALL ACROSS THE AREA FOR CHRISTMAS EVE AND EARLY CHRISTMAS DAY
WITH MODERATE NORTHWEST FLOW ALOFT ACROSS THE STATE AS ANOTHER
UPPER TROUGH TRANSLATES ACROSS THE NORTHERN ROCKIES. THE 12Z ECMWF
IS STILL A TAD DEEPER WITH SAID SYSTEM AND CONTINUES TO PRINT OUT
SOME QPF ACROSS THE EASTERN MTS TUESDAY NIGHT...THOUGH WITH ITS H7
FLOW PROGGED TO REMAIN NORTH TO NORTHWEST...ANY SNOW WOULD GENERALLY
REMAIN SOUTH OF HIGHWAY 50 ACROSS THE SOUTHERN I-25 CORRIDOR. AT ANY
RATE...MODEL CONSENSUS KEEPS SLIGHT POPS ACROSS THE HIGHER TERRAIN
AS WELL AS ALONG THE PALMER DVD AND RATON MESA FOR LATE TUESDAY
AFTERNOON THROUGH EARLY WEDNESDAY MORNING AND HAVE STAYED THE COURSE
FOR NOW. AS FOR TEMPS...WESTERLY FLOW AHEAD OF SAID SYSTEM LOOKS TO
KEEP BREEZY WINDS AND WARMING TEMPERATURES ACROSS THE STATE MONDAY
NIGHT AND TUESDAY...WITH ANOTHER WEAK COLD FRONT MOVING ACROSS THE
PLAINS CHRISTMAS EVE HELPING TO COOL HIGHS TO NEAR SEASONAL AVERAGES
FOR CHRISTMAS DAY.
WEDNESDAY NIGHT-SATURDAY...MODERATE NORTHWEST FLOW PROGGED ACROSS
THE REGION THROUGH THE REST OF THE EXTENDED PERIOD WITH A FEW MINOR
DISTURBANCES MOVING THROUGH THE FLOW ACROSS THE NORTHERN ROCKIES AND
INTO THE NORTHERN HIGH PLAINS. THIS WILL KEEP THE AREA GENERALLY
WARM AND DRY...SAVE A FEW OCCASIONAL FLURRIES ACROSS THE HIGHER
TERRAIN OF THE CENTRAL MTS...AS TEMPERATURES WARM BACK TO ABOVE
SEASONAL LEVELS THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 250 PM MST SAT DEC 21 2013
SNOW SHOWERS WILL CONTINUE TO DEVELOP AND SPREAD TO THE SOUTHEAST
ACROSS THE AREA THROUGH THE LATE AFTERNOON AND EARLY EVENING. STILL
APPEARS THAT KCOS AND KALS MAY SEE PASSING -SHSN THIS EVENING...WITH
SOME BRIEF MVFR CIGS/VIS. LOWER CIGS/VIS WILL LIKELY OCCUR ACROSS
THE SE MTS...WITH IFR TO LIFR CONDITIONS AT TIMES. KPUB WILL HAVE
THE LEAST THREAT OF BEING IMPACTED BY SNOW...SO HAVE KEPT CIGS
PRIMARILY VFR. AS FOR SNOWFALL...SHOULD SEE LESS THAN AN INCH AT
THE KCOS AND KALS TERMINALS. -SHSN WILL TAPER OFF FROM NORTHWEST TO
SOUTHEAST OVERNIGHT...WITH IMPROVING CONDITIONS AT THE KCOS AND KPUB
TAF SITES. WITH CLEARING SKIES OVERNIGHT...KALS MAY SEE A RETURN OF
IFR TO LIFR CIGS/VIS WITH PATCHY GROUND FOG SUNDAY MORNING AND HAVE
PUT THIS IN THE TAF BETWEEN 12Z AND 16Z.
VFR CONDITIONS WILL RETURN FOR MOST OF THE REGION ON SUNDAY. THE
EXCEPTION WILL BE SOME MVFR TO IFR CIGS AT TIMES ACROSS THE
CENTRAL MOUNTAINS WHERE SCATTERED LIGHT OROGRAPHIC SNOW SHOWERS WILL
CONTINUE. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KT
LONG TERM...MW
AVIATION...KT
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1238 PM MST SAT DEC 21 2013
.UPDATE...BASED ON LATEST RADAR TRENDS...BAND OF SNOW IS SHIFTING
SOUTHWARD AND AIRMASS IS SATURATING WITH LIGHT SNOW MOVING INTO
FORT COLLINS. THIS WILL CONTINUE TO SPREAD SOUTHWARD THROUGH THE
REST OF THE AFTERNOON...SO HAVE FURTHER INCREASED POPS IN/NEAR THE
FOOTHILLS. EARLIER ARRIVAL LOOKS LIKE AN EARLIER DEPARTURE AS
WELL...WITH MOST SNOW IN THE LOWER ELEVATIONS OVER BY MIDNIGHT.
&&
.AVIATION...MOVED UP TIMING OF SNOW BASED ON LATEST RADAR TRENDS.
SHOULD REACH KBJC BY 22Z AND KDEN BY 23Z-00Z.
&&
.PREV DISCUSSION... /ISSUED 1108 AM MST SAT DEC 21 2013/
UPDATE...BAND OF MID LEVEL MOISTURE AND LIGHT SNOW WAS CURRENTLY
SPREADING ACROSS THE MOUNTAINS AND FAR NORTHER BORDER AREA. MOST
OF THIS IS VIRGA ON THE PLAINS RIGHT NOW...BUT CONTINUED WEAK LIFT
AND WEAK ANTICYCLONIC UPSLOPE FLOW SHOULD EVENTUALLY SATURATE THE
LOWER LEVELS LATER THIS AFTERNOON INTO THE EVENING. GIVEN CURRENT
RADAR TRENDS AND SHORT RANGE MODEL GUIDANCE...HAVE INCREASED THE
AFTERNOON POPS IN/NEAR THE FOOTHILLS. LATEST RAP RUNS SEEM TO GET
A LITTLE TOO EXCITED ABOUT SNOW AMOUNTS AGAINST THE FRONT RANGE
THIS EVENING...BUT THERE IS SOME LOW/MID LEVEL INSTABILITY SO WILL
CONTINUE TO MONITOR POTENTIAL SNOW ACCUMULATIONS. AT THIS
TIME...STILL LOOKING LIKE MOST PLAINS LOCATIONS SHOULD BE AN INCH
OR LESS. IN THE MOUNTAINS...OROGRAPHIC HELP WILL LIKELY PROVIDE
LOW END ADVISORY AMOUNTS THROUGH SUNDAY MORNING.
AVIATION...FOG IS FINALLY LIFTING AT KDEN...ONE OF THE LAST
PLACES TO CLEAR. NEXT WEATHER CONCERN IS SNOW AS ECHOES ALREADY
FILLING IN NEAR THE WYOMING BORDER. THESE WILL ADVANCE SLOWLY
SOUTHWARD WITH A LOWERING OF THE CLOUD DECK AND EXPECTED ILS
LANDING CONDITIONS DEVELOPING BY 21Z-22Z. LATEST TRENDS SEEM TO BE
A LITTLE FASTER SO THERE IS ALSO A CHANCE OF LIGHT SNOW DEVELOPING
AS EARLY AS 22Z...BUT MAIN THREAT OF SNOW AND IFR CONDITIONS IS
00Z-08Z. ACCUMULATIONS AT THE FRONT RANGE AIRPORTS MOST LIKELY AN
INCH OR LESS...AND KDEN WILL LIKELY BE ON THE EDGE OF THE
ACCUMULATING SNOW.
PREV DISCUSSION... /ISSUED 824 AM MST SAT DEC 21 2013/
AVIATION...DENSE FOG AT KDEN WITH RVRS MAINLY BELOW 1000 FT. THE
FOG HAS LIFTED AT KBJC WITH ONLY LIGHT FOG AT KAPA...AND EROSION
SHOULD CONTINUE FROM THE WEST/WEST-SOUTHWEST AS SURFACE WINDS
ARE TRENDING THAT WAY. EXACT TIMING OF DISSIPATION AT KDEN IS
DIFFICULT DUE TO HIGH CLOUDS MOVING OVER THE TOP...BUT AT THIS
TIME EXPECT SOME IMPROVEMENT STARTING 16Z AND TOTAL EROSION
EXPECTED BY 17Z-18Z. WILL CONTINUE TO MONITOR.
PREV DISCUSSION... /ISSUED 528 AM MST SAT DEC 21 2013/
UPDATE...
SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO
HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO
FORT MORGAN TO DENVER LINE.
AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED
DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER
AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z.
PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/
SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM
FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT
SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW
FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS
NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE
IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE
OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD
INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER
WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN.
OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH
COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND
OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S
OVER THE PLAINS.
BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND
ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW
INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES
ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND
NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN
INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN
AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO.
LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF
THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT
DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS.
AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG
NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF
SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND
PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY
MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER
PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE
MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF
MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY
EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING
SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO.
GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE
PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL
INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY
EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST
CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED
POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY
EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z
WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW
ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH
VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS
SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES
AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE
LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST
FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES
OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY
MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR...
EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER.
THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO
PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS
MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH
MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST
COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR
TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG
ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND
ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT.
WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN
PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF
THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT
WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT
CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS
DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND
FRIDAY.
AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY
SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE
HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE
MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE
DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE
POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE
MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS
THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP.
FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT
WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF
LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF
ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH
IMPROVING CONDITIONS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON MST SUNDAY FOR COZ031-033-034.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....BAKER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1108 AM MST SAT DEC 21 2013
.UPDATE...BAND OF MID LEVEL MOISTURE AND LIGHT SNOW WAS CURRENTLY
SPREADING ACROSS THE MOUNTAINS AND FAR NORTHER BORDER AREA. MOST
OF THIS IS VIRGA ON THE PLAINS RIGHT NOW...BUT CONTINUED WEAK LIFT
AND WEAK ANTICYCLONIC UPSLOPE FLOW SHOULD EVENTUALLY SATURATE THE
LOWER LEVELS LATER THIS AFTERNOON INTO THE EVENING. GIVEN CURRENT
RADAR TRENDS AND SHORT RANGE MODEL GUIDANCE...HAVE INCREASED THE
AFTERNOON POPS IN/NEAR THE FOOTHILLS. LATEST RAP RUNS SEEM TO GET
A LITTLE TOO EXCITED ABOUT SNOW AMOUNTS AGAINST THE FRONT RANGE
THIS EVENING...BUT THERE IS SOME LOW/MID LEVEL INSTABILITY SO WILL
CONTINUE TO MONITOR POTENTIAL SNOW ACCUMULATIONS. AT THIS
TIME...STILL LOOKING LIKE MOST PLAINS LOCATIONS SHOULD BE AN INCH
OR LESS. IN THE MOUNTAINS...OROGRAPHIC HELP WILL LIKELY PROVIDE
LOW END ADVISORY AMOUNTS THROUGH SUNDAY MORNING.
&&
.AVIATION...FOG IS FINALLY LIFTING AT KDEN...ONE OF THE LAST
PLACES TO CLEAR. NEXT WEATHER CONCERN IS SNOW AS ECHOES ALREADY
FILLING IN NEAR THE WYOMING BORDER. THESE WILL ADVANCE SLOWLY
SOUTHWARD WITH A LOWERING OF THE CLOUD DECK AND EXPECTED ILS
LANDING CONDITIONS DEVELOPING BY 21Z-22Z. LATEST TRENDS SEEM TO BE
A LITTLE FASTER SO THERE IS ALSO A CHANCE OF LIGHT SNOW DEVELOPING
AS EARLY AS 22Z...BUT MAIN THREAT OF SNOW AND IFR CONDITIONS IS
00Z-08Z. ACCUMULATIONS AT THE FRONT RANGE AIRPORTS MOST LIKELY AN
INCH OR LESS...AND KDEN WILL LIKELY BE ON THE EDGE OF THE
ACCUMULATING SNOW.
&&
.PREV DISCUSSION... /ISSUED 824 AM MST SAT DEC 21 2013/
AVIATION...DENSE FOG AT KDEN WITH RVRS MAINLY BELOW 1000 FT. THE
FOG HAS LIFTED AT KBJC WITH ONLY LIGHT FOG AT KAPA...AND EROSION
SHOULD CONTINUE FROM THE WEST/WEST-SOUTHWEST AS SURFACE WINDS
ARE TRENDING THAT WAY. EXACT TIMING OF DISSIPATION AT KDEN IS
DIFFICULT DUE TO HIGH CLOUDS MOVING OVER THE TOP...BUT AT THIS
TIME EXPECT SOME IMPROVEMENT STARTING 16Z AND TOTAL EROSION
EXPECTED BY 17Z-18Z. WILL CONTINUE TO MONITOR.
PREV DISCUSSION... /ISSUED 528 AM MST SAT DEC 21 2013/
UPDATE...
SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO
HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO
FORT MORGAN TO DENVER LINE.
AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED
DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER
AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z.
PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/
SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM
FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT
SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW
FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS
NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE
IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE
OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD
INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER
WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN.
OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH
COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND
OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S
OVER THE PLAINS.
BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND
ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW
INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES
ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND
NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN
INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN
AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO.
LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF
THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT
DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS.
AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG
NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF
SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND
PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY
MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER
PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE
MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF
MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY
EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING
SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO.
GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE
PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL
INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY
EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST
CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED
POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY
EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z
WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW
ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH
VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS
SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES
AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE
LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST
FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES
OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY
MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR...
EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER.
THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO
PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS
MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH
MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST
COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR
TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG
ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND
ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT.
WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN
PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF
THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT
WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT
CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS
DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND
FRIDAY.
AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY
SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE
HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE
MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE
DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE
POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE
MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS
THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP.
FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT
WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF
LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF
ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH
IMPROVING CONDITIONS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON MST SUNDAY FOR COZ031-033-034.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....BAKER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1042 AM MST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 319 AM MST SAT DEC 21 2013
...SOME SNOW FOR THE MOUNTAINS THROUGH THIS EVENING...
MAIN FORECAST CHALLENGE TODAY IS STILL THE EXTENT OF LOW CLOUDS
AND FOG OVER THE PLAINS AND VALLEYS. A STUBBORN PATCH OF STRATUS AND
FOG HAS HUNG ON OVER NRN PUEBLO...SRN EL PASO...AND CROWLEY COUNTIES
AND AS OF 230 AM STILL SHOWS NO SIGNS OF DISSIPATING AS WINDS REMAIN
VERY LIGHT. GUIDANCE IS AGAIN NOT VERY HELPFUL...WITH NONE OF THE
HIGH RES MODELS SHOWING ANY FOG DESPITE THE CURRENT CONDITIONS. THE
RAP SOUNDING HAD FOG AT KCOS...BUT DISSIPATING QUICKLY AFTER
09Z...WHICH OBVIOUSLY IS NOT HAPPENING. THE SAN LUIS VALLEY ALSO
PROBLEMATIC...AS SOME GUIDANCE...LIKE THE NAM...SHOWING SATURATED
LOW LEVELS PERSISTING THROUGH THE DAY...WHILE THE RAP IS MUCH MORE
OPTIMISTIC. HIGH RES WRF LOOKS LIKE A REASONABLE COMPROMISE FOR THE
VALLEY...KEEPING THE LOW CLOUDS AROUND THROUGH MID MORNING...THEN
INCREASING CLOUDS LATER TODAY AS THE NRN BRANCH SHORTWAVE SWINGS
THROUGH OUR AREA. WILL STAY ON THE PESSIMISTIC SIDE OF THE FORECAST
AND KEEP THE AREA CLOUDY WITH TEMPS ON THE LOW SIDE OF GUIDANCE...OR
20S FOR THE MTS AND HIGH VALLEYS AND 30S FOR THE PLAINS.
BEST CHANCE OF SNOW FOR MOST OF THE AREA STILL LOOKS TO BE LATE THIS
AFTERNOON THROUGH THIS EVE AS THE WAVE MOVES ACROSS. EXPECT THE BEST
ACCUMS TO COME OVER THE HYR ELEVATIONS OF THE SANGRES..WETS...AND
RAMPARTS. COULD SEE LOW END ADVISORY AMTS ABOVE 10000 FEET...IN THE
3 TO 6 INCH RANGE...BUT IMPACT SHOULD BE MINIMAL SO WILL HOLD OFF
FROM ANY HEADLINES FOR NOW. MAY HAVE TO REEVALUATE IF 12Z RUNS SHOW
AN UPWARD TREND. ONGOING LOW POPS FOR THE I-25 CORRIDOR THIS EVENING
LOOK ON TARGET...BUT NOT EXPECTING MUCH IF ANY ACCUMULATION. PRECIP
SHOULD WIND DOWN AFTER MIDNIGHT TONIGHT...AND IT WILL BE ANOTHER
COLD NIGHT WITH TEMPS IN THE SINGLE DIGITS AND TEENS FOR THE MTS
AND PLAINS RESPECTIVELY. ROSE
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 319 AM MST SAT DEC 21 2013
BY THE BEGINNING OF THIS PERIOD (12Z SUNDAY)...SHORTWAVE TROUGH IN
THE NW FLOW ALOFT WILL BE EXITING THE REGION. A FEW SNOW SHOWERS
WILL BE POSSIBLE EARLY IN THE DAY ACROSS THE PIKES PEAK REGION AND
S MTNS...BUT SHOULD END BY NOON. SNOW SHOWERS WILL CONTINUE ACROSS
THE C MTNS (NW SLOPES) THROUGHOUT THE DAY.
SUNDAY NIGHT ANOTHER WEAK WAVE WILL MOVE SOUTHEAST IN THE NW FLOW
ALOFT. THIS WILL KEEP SNOW SHOWERS ONGOING OVER THE C MTNS. SOME
SNOW SHOWERS WILL ALSO BE POSSIBLE IN NE COLO AND WILL TRACK
SOUTHEAST...BUT THESE SNOW SHOWERS SHOULD STAY OUT OF THE NWS PUB
CWA.
MONDAY INTO EARLY TUESDAY...WEAK RIDGING ALOFT WILL OCCUR...AND THIS
SHOULD BRING PARTLY CLOUDY SKIES TO THE REGION. HOWEVER WE MAY SEE
SOME WAVE CLOUDS ALONG THE GREATER I-25 CORRIDOR REGION DURING THIS
PD. TEMPS SHOULD BE AOA SEASONABLE VALUES MON AND TUE.
LATER ON TUESDAY ANOTHER COOL FRONT WILL MOVE ACROSS THE REGION LATE
IN THE DAY. THE 00Z GFS WAS DRY WITH THIS SYSTEM WHILE THE EC
CONTINUES TO BE A BIT STRONGER...AND BREAKS OUT SOME LIGHT PRECIP
OVER THE GREATER S MTN REGION XMAS EVE INTO EARLY XMAS DAY. FOR THIS
REASON I KEPT SOME SLIGHT POPS FOR THE PIKES PEAK REGION AND S
MTNS/RATON MESA REGION.
FOR THE REST OF THE PD...NW FLOW ALOFT CONTINUES WITH ANOTHER WEAK
SHORT WAVE MOVING ACROSS THE REGION THU AFTERNOON. THIS WAVE WILL
LIKELY BE DRY WITH A WEAK SURGE MOVING ACROSS THE PLAINS DURING THE
DAY THU. /HODANISH
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1010 AM MST SAT DEC 21 2013
A WEATHER SYSTEM WILL MOVE THROUGH THE REGION THIS EVENING
SPREADING A QUICK ROUND OF SNOW IN AND NEAR THE MOUNTAINS BETWEEN
20Z AND 12Z. KALS AND KCOS WILL SEE THE BEST CHANCE OF
EXPERIENCING SOME -SHSN...THOUGH ANY ACCUMULATIONS AT THE
TERMINALS WILL LIKELY STAY BELOW AN INCH. CIGS/VIS MAY BRIEFLY DROP
INTO THE MVFR CATEGORY WITH -SHSN...WITH LOWER CIGS/VIS OVER/NEAR
THE MOUNTAINS. CLEARING CONDITIONS WILL TAKE PLACE FROM NW TO SE
AFTER 06Z. GUIDANCE AND BUFKIT MODEL SOUNDINGS SUGGEST KALS WILL
GO DOWN IN FOG AGAIN SUNDAY MORNING BEHIND THE SYSTEM ONCE CLEARING
TAKES PLACE.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ROSE
LONG TERM...HODANISH
AVIATION...KT
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
1112 AM CST Sat Dec 21 2013
...Updated for Aviation...
.SHORT TERM...(This evening through Saturday)
ISSUED AT 355 AM CST SAT DEC 21 2013
A strong shortwave trough centered west of El Paso early this
morning will eject northeastward across the southern plains through
this evening. Plenty of low level moisture was being ejected into
this system from the south. The deformation/trowal will set up
across southwestern Kansas later today and the 06z NAM and 00 UTC
ECMWF seem to have the best handle on the distribution and amounts
of snow. Given that this is a fast moving system, snow totals of 2
to 5 inches are generally expected in the advisory area along and
southeast of a line from Elkhart to Garden City to Ness City to
LaCrosse, with the highest amounts from Meade eastward into Barber
and Pratt counties. A few locations could reach 6 inches. The snow
may start off as sleet or freezing rain in south central Kansas
later this morning since RAP soundings show an elevated warm layer
around 1C through 18Z. Temperatures may rise into the upper 20s and
lower 30s before the snow arrives, and then fall back into the mid
20s. Afternoon temperatures will be warmer in places like Syracuse,
Scott City and Dighton where not much in the way of snow is
expected. Temperatures tonight will be held up by 10kt north winds
and cloud cover; but with fairly chilly air pushing southward out of
the northern plains in the wake of the storm system, temperatures
should drop into the teens.
.LONG TERM...(Sunday through Friday)
ISSUED AT 246 AM CST SAT DEC 21 2013
Models this morning were in fairly good agreement with lifting a
weakening upper level trough across the Mid Mississippi Valley on
Sunday. At the same time a northern branch upper level trough will
move out of the Rockies and across the Central Plains as an area
of high pressure at the surface builds into western Kansas.
Although no measurable precipitation is expected with this next
system, there will be some increasing clouds late Sunday into
Sunday night. This increasing cloud cover will limit how cold
temperatures will fall Sunday night, however give light winds and
fresh snow cover across western Kansas will still undercut the
coolest guidance for overnight lows. Temperatures falling back
into the single digits still looks reasonable. Lows near zero no
out of the question near the Oklahoma border if skies remain clear
for several hours after midnight.
Westerly downslope flow will improve early next week which will
allow temperatures to gradually warm. Snow cover will limit how
much warming will occur Monday and Tuesday, but at this time the
latest CRExtendFcst_Init still looks reasonable. Where the heavier
snowfall is expected later today the afternoon temperatures are
expected to warm into the upper 30s by Tuesday afternoon.
Elsewhere highs in the mid to upper 40s still appear likely given
the 850mb temperature trends from the GFS and ECMWF. This slow
warming trend will briefly end mid week as a cold front drops
south across Kansas Tuesday night Wednesday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1107 AM CST SAT DEC 21 2013
The track of the upper level storm and attendant heavy snow axis
is forecast to be just east of the KDDC terminal. Some MVFR conditions
are possible mainly at KDDC with light snow and north winds around
10kts after 19Z through around 05Z before the snow moves off to
the east.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 30 18 28 4 / 80 90 0 0
GCK 31 18 29 9 / 20 20 0 0
EHA 28 18 32 17 / 50 40 0 0
LBL 28 18 29 11 / 80 40 0 0
HYS 32 16 28 10 / 20 30 10 20
P28 29 19 27 3 / 100 100 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Midnight CST tonight FOR KSZ046-
063>066-075>081-084>090.
&&
$$
SHORT TERM...Finch
LONG TERM...Burgert
AVIATION...Kruse
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
352 PM EST SAT DEC 21 2013
.SYNOPSIS...
A STRONG COLD FRONT ACCOMPANIED BY GUSTY WINDS PASSES SUNDAY.
AREA RIVERS WILL BE ON THE RISE THROUGH MONDAY. AN UPPER LEVEL
DISTURBANCE BRINGS SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. MUCH
CALMER WEATHER THE BALANCE OF THE HOLIDAY WEEK WITH BELOW NORMAL
TEMPERATURES.
&&
.NEAR TERM /THROUGH SUNDAY/...
SOUTHERLY FLOW CONTINUES TO INCREASE AHEAD OF DEEPENING SFC CYCLONE
WHICH IS EVIDENT BY VIEWING REGIONAL RADAR MOSAIC AS PLUME OF RAIN
CONTINUES TO SHIFT NNE. DRY WEATHER HAS ALREADY REACHED NRN WV AND
WRN MD AND WILL CONTINUE TO OVERSPREAD MUCH OF THE CWA THIS
EVENING. PARTIAL CLEARING OVER THE NORTHERN WV MOUNTAINS HAS
ALLOWED TEMPS TO SOAR INTO THE MID 70S. THIS AIR WILL MAKE IT TO
THE MASON DIXON LINE...WHILE 60S SHALL ENCOMPASS WRN PA AND THE
NRN WV PANHANDLE. TEMPS WILL NOT FALL MUCH TONIGHT AS BOUNDARY
LAYER REMAINS WELL MIXED.
COLD FRONT CROSSES SUNDAY MORNING INTO EARLY AFTERNOON. BAND OF
MODERATE TO HEAVY SHOWERS WILL BE OUT AHEAD OF IT. THERMODYNAMIC
PARAMETERS STILL ARE NOT OVERLY IMPRESSIVE DUE TO THE TIME OF DAY
IT CROSSES. UPPER LEVEL DYNAMICS DO NOT WOW ME EITHER AS STRONG
AGEOSTROPHIC FORCING RESULTING FROM JET COUPLING IS NOT PRESENT.
CONTINUED TO OMIT THUNDER FROM FCST...DESPITE SPC BRINGING SLIGHT
RISK TO NRN WV PANHANDLE. GUSTY WINDS UPWARDS OF 40 MPH MAY OCCUR BASED
ON MOMENTUM TRANSFER. THIS COULD KNOCK AROUND OUTDOOR CHRISTMAS
DECORATIONS. HRRR AGREES WITH THIS BASED ON 10M WIND GUST FIELD.
HEAVY RAIN REMAINS A CONCERN ACROSS THE FLOOD WATCH AREA. AT THIS
TIME...ADDITIONAL AMOUNTS UPWARDS OF AN INCH COULD LEAD TO
FLOODING. THE PERIOD OF DRY WEATHER THIS EVENING HELPS OFFSET A
WIDESPREAD THREAT OF HIGH WATER IN THE WATCH AREA.
SIDED WITH WARMEST GUIDANCE TONIGHT.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
COLD FRONT WILL BE EAST OF OUR AREA SUNDAY NIGHT AS ANY QPF LEFT
OVER ASSOCIATED WITH BAROCLINIC ZONE WILL AFFECT NRN WV MTNS AND
WRN MD UNTIL MID EVENING. A BRIEF PERIOD OF CLEARING MON EVENING
BEFORE CLOUDS ASSOCIATED WITH THE SURGE OF COLD AIR AND LOWER MID
LVL HEIGHTS ARRIVE FROM THE WEST.
MID LVL TROUGH SWEEPS THROUGH MON NGT - TUE. THIS IS ACCOMPANIED
BY MUCH COLDER AIR AS H8 TEMPS PLUMMET BACK INTO THE NEGATIVE MID
TEENS BY 12Z TUES. SCATTERED SNOW SHOWERS AND LAKE EFFECT SNOW
SHOWERS ARE PREDICTED MON NGT INTO TUES EVENING. WIND TRAJECTORY
IS NOT FAVORABLE FOR SIGNIFICANT SNOW ACCUMULATIONS. OUTSIDE THE
SNOW BELT OF NWRN PA...LOOK FOR MINOR ACCUMS AT BEST GIVEN SHORT
DURATION AND LACK OF FAVORABLE SNOW DYNAMICS AS NEEDED UPPER LEVEL
TEMPERATURES ARE BELOW REGION OF UPWARD VERTICAL MOTION.
ANTICYCLONIC FLOW RAPIDLY ENSUES DURING THE PREDAWN HOURS WEDNESDAY.
THIS WILL SHUT OFF THE LAKE EFFECT MACHINE AS SCOUR OUT CLOUDS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
FOCUSED EFFORTS ON NEAR AND SHORT TERM TODAY...LATEST NUMERICAL
MODELS REMAIN CONSISTENT WITH WEATHER PATTER OVER THE LONG RANGE.
BELOW NORMAL TEMPS ARE PROJECTED FOR MUCH OF THE EXTENDED.
PREVIOUS DISCUSSION FOLLOWS:
BLDG HIGH PRES SHOULD END ANY SNOW SHWRS TUE EVE...WITH DRY WEATHER
CONTG WED. A WK CLIPPER IS PROGGED FOR THU...THOUGH TIMING AND
STRENGTH DIFFERENCES IN THE MDLS PRECLUDE MORE THAN A SLGT CHC
MENTION FOR SNOW SHWRS ATTM. BLDG HIGH PRES IS EXPD AGAIN BY THE
END OF THE WK. OVERALL...TEMPS SHOULD AVG BLO SEASONAL LVLS THRU
THE PD.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
FRONTAL BOUNDARY STALLED ACROSS NW PA WILL LIFT NORTH THIS EVENING
AND ALLOW FOR A BREAK IN PRECIP FOR TERMINALS
SOUTH OF I80 THIS OVERNIGHT. DUJ AND FKL HOWEVER ARE MORE LIKELY
TO SEE SHOWERS ONGOING THROUGH THE NIGHT WITH CONTINUED MVFR
CONDITIONS. FOR SOUTHERN TERMINALS...EXPECT MAINLY VFR BY EARLY EVENING
AND WITH SOUTHWESTERLY WINDS HELPING KEEP THINGS WELL MIXED
OVERNIGHT...DO NOT ANTICIPATE ANY ADDITIONAL VISIBILITY
RESTRICTIONS DEVELOPING.
.OUTLOOK.../18Z SUNDAY THROUGH THURSDAY/...
CONTINUED IFR RESTRICTIONS WILL BE POSSIBLE MONDAY NIGHT THROUGH
TUESDAY NORTH OF INTERSTATE 80 DUE TO LAKE EFFECT SNOW SHOWERS.
OTHERWISE...NO OTHER WIDESPREAD WEATHER RELATED AVIATION HAZARDS
EXISTS.
&&
.HYDROLOGY...
A FLOOD WARNING IS IN EFFECT FOR WILLS CREEK AT CAMBRIDGE
AFFECTING GUERNSEY COUNTY AND THE MUSKINGUM RIVER AT COSHOCTON
AFFECTING COSHOCTON COUNTY. RAINFALL AMOUNTS OF 1.00 TO NEARLY
3.00 INCHES OF RAINFALL ARE EXPECTED OVER THE TUSCARAWAS RIVER AND
MUSKINGUM RIVER BASINS.
SHARP RISES ARE EXPECTED ON RIVERS AND STREAMS ACROSS EASTERN OHIO.
THESE RISES WILL BE SUFFICIENT FOR THE MUSKINGUM RIVER AT COSHOCTON
TO RISE ABOVE FLOOD STAGE SUNDAY AFTERNOON. WILLS CREEK WILL RISE
ABOVE FLOOD STAGE SUNDAY EVENING. MINOR FLOODING IS EXPECTED AT BOTH
LOCATIONS.
A FLOOD ADVISORY IS IN EFFECT FOR THE OHIO RIVER AT THE POINT IN
PITTSBURGH. THE OHIO RIVER IS EXPECTED TO RISE ABOVE 18.0 FEET AND
BEGIN TO FLOOD THE MONONGAHELA RIVER PARKING WHARF SUNDAY AFTERNOON.
THE OHIO RIVER THE CREST IS EXPECTED MONDAY AFTERNOON AT 21.8 FEET.
THIS WILL COMPLETELY FLOOD THE MONONGAHELA PARKING WHARF. AT THIS
TIME FLOOD WATERS ARE NOT EXPECTED TO AFFECT THE 10TH STREET
BYPASS. STRONG RISES ON THE OHIO RIVER ARE FORECAST SUNDAY WITH
CONTINUED ELEVATED LEVELS THROUGH TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR OHZ039>041-048-057.
PA...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR PAZ007>009-013.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
307 PM EST SAT DEC 21 2013
.SYNOPSIS...
A STRONG COLD FRONT ACCOMPANIED BY GUSTY WINDS PASSES SUNDAY.
AREA RIVERS WILL BE ON THE RISE THROUGH MONDAY. AN UPPER LEVEL
DISTURBANCE BRINGS SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. MUCH
CALMER WEATHER THE BALANCE OF THE HOLIDAY WEEK WITH BELOW NORMAL
TEMPERATURES.
&&
.NEAR TERM /THROUGH SUNDAY/...
SOUTHERLY FLOW CONTINUES TO INCREASE AHEAD OF DEEPENING SFC CYCLONE
WHICH IS EVIDENT BY VIEWING REGIONAL RADAR MOSAIC AS PLUME OF RAIN
CONTINUES TO SHIFT NNE. DRY WEATHER HAS ALREADY REACHED NRN WV AND
WRN MD AND WILL CONTINUE TO OVERSPREAD MUCH OF THE CWA THIS
EVENING. PARTIAL CLEARING OVER THE NORTHERN WV MOUNTAINS HAS
ALLOWED TEMPS TO SOAR INTO THE MID 70S. THIS AIR WILL MAKE IT TO
THE MASON DIXON LINE...WHILE 60S SHALL ENCOMPASS WRN PA AND THE
NRN WV PANHANDLE. TEMPS WILL NOT FALL MUCH TONIGHT AS BOUNDARY
LAYER REMAINS WELL MIXED.
COLD FRONT CROSSES SUNDAY MORNING INTO EARLY AFTERNOON. BAND OF
MODERATE TO HEAVY SHOWERS WILL BE OUT AHEAD OF IT. THERMODYNAMIC
PARAMETERS STILL ARE NOT OVERLY IMPRESSIVE DUE TO THE TIME OF DAY
IT CROSSES. UPPER LEVEL DYNAMICS DO NOT WOW ME EITHER AS STRONG
AGEOSTROPHIC FORCING RESULTING FROM JET COUPLING IS NOT PRESENT.
CONTINUED TO OMIT THUNDER FROM FCST...DESPITE SPC BRINGING SLIGHT
RISK TO NRN WV PANHANDLE. GUSTY WINDS UPWARDS OF 40 MPH MAY OCCUR BASED
ON MOMENTUM TRANSFER. THIS COULD KNOCK AROUND OUTDOOR CHRISTMAS
DECORATIONS. HRRR AGREES WITH THIS BASED ON 10M WIND GUST FIELD.
HEAVY RAIN REMAINS A CONCERN ACROSS THE FLOOD WATCH AREA. AT THIS
TIME...ADDITIONAL AMOUNTS UPWARDS OF AN INCH COULD LEAD TO
FLOODING. THE PERIOD OF DRY WEATHER THIS EVENING HELPS OFFSET A
WIDESPREAD THREAT OF HIGH WATER IN THE WATCH AREA.
SIDED WITH WARMEST GUIDANCE TONIGHT.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
COLD FRONT WILL BE EAST OF OUR AREA SUNDAY NIGHT AS ANY QPF LEFT
OVER ASSOCIATED WITH BAROCLINIC ZONE WILL AFFECT NRN WV MTNS AND
WRN MD UNTIL MID EVENING. A BRIEF PERIOD OF CLEARING MON EVENING
BEFORE CLOUDS ASSOCIATED WITH THE SURGE OF COLD AIR AND LOWER MID
LVL HEIGHTS ARRIVE FROM THE WEST.
MID LVL TROUGH SWEEPS THROUGH MON NGT - TUE. THIS IS ACCOMPANIED
BY MUCH COLDER AIR AS H8 TEMPS PLUMMET BACK INTO THE NEGATIVE MID
TEENS BY 12Z TUES. SCATTERED SNOW SHOWERS AND LAKE EFFECT SNOW
SHOWERS ARE PREDICTED MON NGT INTO TUES EVENING. WIND TRAJECTORY
IS NOT FAVORABLE FOR SIGNIFICANT SNOW ACCUMULATIONS. OUTSIDE THE
SNOW BELT OF NWRN PA...LOOK FOR MINOR ACCUMS AT BEST GIVEN SHORT
DURATION AND LACK OF FAVORABLE SNOW DYNAMICS AS NEEDED UPPER LEVEL
TEMPERATURES ARE BELOW REGION OF UPWARD VERTICAL MOTION.
ANTICYCLONIC FLOW RAPIDLY ENSUES DURING THE PREDAWN HOURS WEDNESDAY.
THIS WILL SHUT OFF THE LAKE EFFECT MACHINE AS SCOUR OUT CLOUDS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
FOCUSED EFFORTS ON NEAR AND SHORT TERM TODAY...LATEST NUMERICAL
MODELS REMAIN CONSISTENT WITH WEATHER PATTER OVER THE LONG RANGE.
BELOW NORMAL TEMPS ARE PROJECTED FOR MUCH OF THE EXTENDED.
PREVIOUS DISCUSSION FOLLOWS:
BLDG HIGH PRES SHOULD END ANY SNOW SHWRS TUE EVE...WITH DRY WEATHER
CONTG WED. A WK CLIPPER IS PROGGED FOR THU...THOUGH TIMING AND
STRENGTH DIFFERENCES IN THE MDLS PRECLUDE MORE THAN A SLGT CHC
MENTION FOR SNOW SHWRS ATTM. BLDG HIGH PRES IS EXPD AGAIN BY THE
END OF THE WK. OVERALL...TEMPS SHOULD AVG BLO SEASONAL LVLS THRU
THE PD.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
FRONTAL BOUNDARY STALLED ACROSS NW PA WILL LIFT NORTH THROUGH THE
AFTERNOON AND SHOULD ALLOW FOR A BREAK IN PRECIP FOR TERMINALS
SOUTH OF I80 THIS EVENING AND OVERNIGHT. DUJ AND FKL
HOWEVER ARE MORE LIKELY TO SEE SHOWERS ONGOING THROUGH THE NIGHT
WITH CONTINUED MVFR CONDITIONS. FOR SOUTHERN TERMINALS...EXPECT
MAINLY VFR BY LATE THIS AFTERNOON AND OVERNIGHT...AND WITH
SOUTHWESTERLY WINDS HELPING KEEP THINGS WELL MIXED OVERNIGHT...;DO
NOT ANTICIPATE ANY ADDITIONAL VISIBILITY RESTRICTIONS DEVELOPING.
.OUTLOOK.../18Z SUNDAY THROUGH THURSDAY/...
IFR RESTRICTIONS ARE POSSIBLE MON NGT INTO TUE ACROSS FKL AND DUJ
WITH LAKE EFFECT SNOW SHOWERS. BRIEF MVFR RESTRICTIONS COULD AFFECT
PIT AND LBE DURING THE AFOREMENTIONED TIME FRAME AS WELL.
OTHERWISE...NO OTHER WIDESPREAD WEATHER RELATED AVIATION HAZARDS
EXISTS.
&&
.HYDROLOGY...
A FLOOD WARNING IS IN EFFECT FOR WILLS CREEK AT CAMBRIDGE
AFFECTING GUERNSEY COUNTY AND THE MUSKINGUM RIVER AT COSHOCTON
AFFECTING COSHOCTON COUNTY. RAINFALL AMOUNTS OF 1.00 TO NEARLY
3.00 INCHES OF RAINFALL ARE EXPECTED OVER THE TUSCARAWAS RIVER AND
MUSKINGUM RIVER BASINS.
SHARP RISES ARE EXPECTED ON RIVERS AND STREAMS ACROSS EASTERN OHIO.
THESE RISES WILL BE SUFFICIENT FOR THE MUSKINGUM RIVER AT COSHOCTON
TO RISE ABOVE FLOOD STAGE SUNDAY AFTERNOON. WILLS CREEK WILL RISE
ABOVE FLOOD STAGE SUNDAY EVENING. MINOR FLOODING IS EXPECTED AT BOTH
LOCATIONS.
A FLOOD ADVISORY IS IN EFFECT FOR THE OHIO RIVER AT THE POINT IN
PITTSBURGH. THE OHIO RIVER IS EXPECTED TO RISE ABOVE 18.0 FEET AND
BEGIN TO FLOOD THE MONONGAHELA RIVER PARKING WHARF SUNDAY AFTERNOON.
THE OHIO RIVER THE CREST IS EXPECTED MONDAY AFTERNOON AT 21.8 FEET.
THIS WILL COMPLETELY FLOOD THE MONONGAHELA PARKING WHARF. AT THIS
TIME FLOOD WATERS ARE NOT EXPECTED TO AFFECT THE 10TH STREET
BYPASS. STRONG RISES ON THE OHIO RIVER ARE FORECAST SUNDAY WITH
CONTINUED ELEVATED LEVELS THROUGH TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR OHZ039>041-048-057.
PA...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR PAZ007>009-013.
WV...NONE.
&&
$$
SYNOPSIS...98
NEAR TERM...98
SHORT TERM...98
LONG TERM...98/07
AVIATION...88
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
338 PM EST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 457 AM EST SAT DEC 21 2013
SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN
STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES
ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT
LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW
WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA
UNTIL DAYBREAK ON SUNDAY.
EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN
LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF
ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK
SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT
SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF
OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW
TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP
TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO
THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC
TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT.
EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY
GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE
OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR
REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED
LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO
5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE
AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT
SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT
WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW
TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS.
CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE
THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS
ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS.
THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN
KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS
AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT
EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4
INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE
MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS
ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF
SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN.
ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1
INCH.
MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH
EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL
MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM
TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER
MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY
PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS
TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES
MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS
INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK
SUPERIOR.
SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON
THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF
LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85
AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF
WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING
WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR
SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE
INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL
CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS
MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS
THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS
WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR
SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE
EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE
SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 337 PM EST SAT DEC 21 2013
A LOW PRESSURE SYSTEM MOVING THROUGH THE SRN GREAT LAKES REGION
SUN...WHICH WILL BRING SYNOPTIC SNOW TO THE FAR SERN CWA AND LAKE
ENHANCED SNOW TO MUCH OF THE REST OF THE CWA THROUGH SUN. WITH THE
LONG TERM FORECAST STARTING AT 00Z MON...ALMOST ALL OF THE SYNOPTIC
PRECIP ASSOCIATED WITH THE PREVIOUSLY MENTIONED LOW WILL BE E OF THE
CWA. MORE SYNOPTIC SNOW WILL BE OVER OR JUST W OF THE FAR WRN CWA AT
00Z MON ASSOCIATED WITH A DEEP UPPER TROUGH OVER MN. THE TROUGH WILL
MOVE TO THE CENTRAL CWA BY 00Z TUE THEN E OF THE CWA BY 06Z TUE.
MODELS ARE IN GOOD AGREEMENT ON THE TROUGH WITH THE EXCEPTION OF THE
12Z/21 NAM WHICH HAS THE TROUGH DEEPER AND NEGATIVELY TILTED AND
SEEMS TOO AMPLIFIED. SHOULD SEE AN INVERTED SFC TROUGH STRETCHING
FROM THE SE ACROSS LAKE SUPERIOR THROUGH MUCH OF TUE NIGHT BEFORE A
SFC AND UPPER RIDGE MOVE ON ON TUE.
LAKE ENHANCED SNOW WILL BE ONGOING IN THE NNE-NE LOW LEVEL FOR AT
00Z MON WITH 850MB TEMPS AROUND -15C. WIND FIELDS SHOULD ONLY BACK
SLIGHTLY THROUGH MON...THEN MORE QUICKLY ON MON NIGHT...SO THE
PRIMARY AREAS FAVORED BY THE LAKE ENHANCEMENT WILL BE MARQUETTE AND
BARAGA COUNTIES AS WELL AS GOGEBIC AND ONTONAGON COUNTIES. MODERATE
TO HEAVY SNOW IS EXPECTED OVER THE WRN FAVORED AREAS THROUGH
MON...AND INTO MON NIGHT OVER THE NCENTRAL. IN COORDINATION WITH
SHORT TERM FORECASTER...LAKE EFFECT SNOW ADVISORIES WERE ISSUED FOR
THESE TWO AREAS. GENERALLY...EXPECT SNOW TO BY STEADY...WITH
ADDITIONAL SNOWFALL AMOUNTS SUN NIGHT INTO MON NIGHT OF AROUND A
FOOT OVER THE FAR WRN U.P. AND 8-12 INCHES OVER THE NCENTRAL.
MAINLY FOCUSED ON THE PREVIOUSLY DISCUSSED SHORTER TERM OF THE
FORECAST...BUT WILL BRIEFLY SUMMARIZE MORE SIGNIFICANT CHANGES TO
THIS PART OF THE FORECAST. KEPT POPS HIGHER THAN CONSENSUS FOR TUE
NIGHT THROUGH THU AS LAKE EFFECT AND ENHANCED SNOW IS NOT CAPTURED
WELL BE LOW RES MODELS. A COUPLE OF PERIODS OF COLDER WEATHER ARE IN
STORE...FOR SUN NIGHT THROUGH TUE AND WED NIGHT THROUGH FRI
NIGHT...THE LOWEST TEMPS SHOULD BE MON NIGHT AND THU NIGHT WHERE
TEMPERATURES MAY FALL INTO THE TEENS BELOW ZERO INTERIOR W AND FAR E
ON MON NIGHT AND OVER THE INTERIOR W ON THU NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1243 PM EST SAT DEC 21 2013
KIWD...LIGHT WINDS BECOMING ONSHORE NE DIRECTION SHOULD ENSURE MVFR
CIGS AND LIGHT LAKE SNOW SHOWERS ACROSS THE TAF SITES BY LATE THIS
AFTERNOON. IFR VSBY IN SNOW AND BLSN IS EXPECTED TO DEVELOP AT WRN
TAF SITES LATE TONIGHT ESPECIALLY AS NE WINDS AND INSTABILITY
INCREASES OVER WRN LAKE SUPERIOR. WINDS BECOMING MORE EASTERLY WILL
SCATTER OUT THE LOW CLOUDS AT SAW LATE TONIGHT. WIDESPREAD SNOW IS
EXPECTED TO IMPACT ALL TERMINALS ON SUNDAY AS A LOW PRESSURE SYSTEM
SLIDES ACROSS THE CENTRAL GREAT LAKES REGION. HEAVIEST SNOW WILL
OCCUR AT IWD WITH UPSLOPE NORTHEAST WINDS PROVIDING ADDITIONAL
SUPPORT FOR SNOW OFF LK SUPERIOR. AS A RESULT...VSBYS AT KIWD COULD
LOWER TO LIFR BY LATE SUNDAY MORNING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 457 AM EST SAT DEC 21 2013
LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS
SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS
OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW
PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER
THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW
PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE
FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE
UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH
PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A
LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES.
THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE
SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON
WEDNESDAY...WINDS WILL BECOME WESTERLY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY FROM 9 AM TO 5 PM EST SUNDAY FOR MIZ007-
013-014-085.
LAKE EFFECT SNOW ADVISORY FROM 1 AM EST /MIDNIGHT CST/ SUNDAY TO
MIDNIGHT EST /11 PM CST/ MONDAY NIGHT FOR MIZ002-009.
WINTER WEATHER ADVISORY FROM 5 AM TO 2 PM CST SUNDAY FOR MIZ012.
LAKE EFFECT SNOW ADVISORY FROM 7 AM SUNDAY TO 7 AM EST TUESDAY
FOR MIZ004-005.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 6 AM EST /5 AM CST/ TO 3 PM
EST /2 PM CST/ SUNDAY FOR LSZ162.
HEAVY FREEZING SPRAY WARNING FROM 7 AM SUNDAY TO 7 AM EST MONDAY
FOR LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...TITUS
AVIATION...VOSS
MARINE...JLA
AREA FORECAST DISCUSSION
NWS GAYLORD MI
216 PM EST SAT DEC 21 2013
.SYNOPSIS...
ISSUED AT 457 AM EST SAT DEC 21 2013
QUIET WEATHER IS EXPECTED DURING THE DAY TODAY BEFORE ANOTHER STORM
SYSTEM AFFECTS THE REGION TONIGHT INTO SUNDAY. THIS EVOLVING SYSTEM
WILL LIFT INTO THE NORTHERN OHIO VALLEY SATURDAY NIGHT...BRINGING
LIGHT TO MODERATE AMOUNTS OF SNOW TO THE REGION. COLD AIR WILL
FILTER BACK INTO THE GREAT LAKES MONDAY AND TUESDAY...GENERATING
SOME LAKE EFFECT SNOW...ACROSS PARTS OF NORTHERN MICHIGAN TO BEGIN
THE UPCOMING WORK WEEK. A COUPLE OF ALBERTA CLIPPERS WILL THEN
LIKELY BRINGING SOME LIGHT SNOW FOR CHRISTMAS DAY AND A CHANCE FOR
LIGHT SNOW ON THURSDAY.
&&
.UPDATE...
ISSUED AT 215 PM EST SAT DEC 21 2013
NO BIG CHANGES...HAVE DECREASED SKY COVER ACROSS EASTERN UPPER
MICHIGAN WITH FILTERED SUN UP THAT WAY. REMAINS TO BE SEEN IF SOME
OF THAT LOW LEVEL CLEARING CAN GET DOWN INTO THE TIP OF THE MITT
COUNTIES OR NOT. WILL SEE.
OTHERWISE...PATCHY FREEZING DRIZZLE APPEARS TO HAVE ENDED AND CIGS
ARE COMING UP A BIT...THUS NO NEED TO EXTEND -FZDZ AT THIS POINT.
TO OUR SOUTH...INVERTED SFC TROUGH STRETCHES FROM THE WESTERN GULF
UP THROUGH NEW ENGLAND WITH WIDESPREAD PRECIP ALREADY OCCURRING
ALONG THAT CONVERGENCE AXIS. ANTICIPATED STRONG SHORT WAVE MOVING
THE NRN TEXAS AND ABOUT TO SWING UP THROUGH THE CENTRAL PLAINS AND
INTO THE MIDWEST TONIGHT THEN SWING UP THROUGH LOWER MICHIGAN
DURING THE DAY. SFC LOW ON TRACK TO SPIN UP ALONG THE BAROCLINIC
ZONE AND ADVANCE UP THROUGH NRN OHIO/FAR SE LOWER MICHIGAN EARLY
SUNDAY MORNING BEFORE KICKING INTO THE EASTERN GREAT LAKES THROUGH
THE DAY. ONGOING WARM CONVEYOR PRECIP ALREADY TO OUR SOUTH
WILL INITIALLY PUSH UP INTO PARTS OF NRN LOWER MICHIGAN LATER
TONIGHT BEFORE GETTING PINCHED OFF AND KICKED INTO THE EASTERN
LAKES SUNDAY...FOLLOWED BY A PERIOD OF HEAVIER WRAP AROUND/
DEFORMATION SNOW THROUGH THE DAY SUNDAY...PERIOD OF HEAVIEST SNOW
BETWEEN 15Z AND 21Z AS THE SHORT WAVE SWINGS UP THROUGH LOWER
MICHIGAN.
LITTLE HAS CHANGED WITH THIS SCENARIO AMONGST GUIDANCE SOLUTIONS
OVER THE LAST DAY...AND THE NAM SOLUTION IS STILL THE FURTHER
NORTHERN SOLUTION...TRACKING THE SFC LOW INTO THE THUMB BUT
INTERESTINGLY KEEPS WARM NOSE ALOFT (>0C LAYER) JUST OUT OF THIS
CWA. SO ALL GUIDANCE SOURCES GIVE NRN LOWER MICHIGAN SNOW...WITH
JUST AN OUTSIDE CHANCE OF SLEET OVER THE FAR SE COUNTIES TOWARD
SAGINAW BAY. ONLY MAIN DIFFERENCES AT THIS POINT IS JUST WHERE
HEAVIEST WRAP AROUND QPF BULLSEYE TRACKS THROUGH THE REGION...
AGAIN WITH THE NAM A LITTLE FURTHER NORTHWARD DISPLACED. BUT OUR
CONSENSUS FORECAST KEEPS HEAVIEST QPF BULLSEYE TRACKING RIGHT UP
ACROSS NRN LOWER MICHIGAN...POSSIBLY SKIMMING FAR EASTERN UPPER
MICHIGAN WITH SOME HEAVIER SNOW.
AS FAR AS SNOW AMOUNTS GO...BASICALLY HAVE A 2 PERIOD (TONIGHT AND
TOMORROW) COMBINED TOTAL OF 0.4 TO 0.6 INCHES TOTAL LIQUID OVER
NRN LOWER MICHIGAN...0.2 TO 0.4 INCHES IN EASTERN UPPER MICHIGAN.
SNOW ACCUMULATIONS WILL OF COURSE BE DEPENDENT ON JUST WHAT
SNOW:WATER RATIOS ARE REALIZED. HAVE <10:1 RATIOS OVER THE S/SE
COUNTIES AND 10-15:1 FOR NRN HALF OF THE CWA...YIELDING A NICE 4
TO 7 INCHES SWEET SPOT CENTERED UP THROUGH NRN LOWER MICHIGAN AND
LESSER AMOUNTS TOWARD SAGINAW BAY. NOT MUCH DIFFERENT WITH WHAT WE
HAVE BEEN FORECASTING FOR THE LAST DAY OR TWO. PLAN NO CHANGES TO
THE CURRENT WINTER WEATHER ADVISORIES...ALTHOUGH WE MAY PUT
EASTERN UPPER MICHIGAN INTO AN ADVISORY FOR SOME BEEFIER SNOWFALL
OVER THE EASTERN PART OF THOSE COUNTIES.
UPDATE ISSUED AT 1028 AM EST SAT DEC 21 2013
NO MAJOR CHANGES TO THE FORECAST AT THIS HOUR...AND AN OVERALL
QUIET...ALBEIT CLOUDY DAY ON TAP FOR THE NORTH WOODS. 12Z APX
REVEALING A FAIRLY DEEP SATURATED LOW LAYER UP TO NEARLY 750
MB...ALTHOUGH THE TEMP/DEWPOINT SPREAD DOES OPEN A BIT IN LAYERS.
NONETHELESS...HAVE HAVE A FEW REPORTS OF -FZDZ AROUND THE TVC AREA
AND OBS AROUND THE GRAND TRAVERSE BAY AREA DOES HINT AT PATCHY
FZDZ VIA REDUCED VSBYS AND LOW CIGS. EVEN GLR REPORTING LOW VSBY
AND FZFG. SO...HAVE ADDED PATCHY -FZDZ TO THE FORECAST THROUGH THE
MORNING AND EVEN ISSUED AN SPS TO COVER SOME POTENTIAL SLICK
SPOTS/BLACK ICE THIS MORNING. RUC FORECAST SOUNDINGS SHOW ONGOING
LOW LEVEL DRYING/OPENING THE SOUNDINGS JUST A BIT THROUGH THE
AFTERNOON...SUGGESTING -FZDZ WILL END. WILL SEE.
OTHERWISE...JUST INGESTING OBSERVATIONAL TRENDS AND INCOMING 12Z
GUIDANCE TO SEE WHAT...IF ANY ADJUSTMENTS MAY BE NEEDED TO THE
UPCOMING EVENT LATER TONIGHT THROUGH SUNDAY. NO BIG SURPRISES SO
FAR.
UPDATE ISSUED AT 628 AM EST SAT DEC 21 2013
UPDATED SKY GRIDS. WINDS ARE TURNING LIGHT OUT OF THE NORTH WITH
LITTLE TO NO SPEEDS REMAINING 5 KTS OR LESS. SLOWED ANY SORT OF
GOOD LOW LEVEL DRYING AND AM KEEPING LOW CLOUDS AROUND THROUGH A
GOOD PORTION OF THE DAY...PLUS A PLETHORA OF MID AND HIGH LEVEL
CLOUDS REMAINS OVER MUCH OF THE REGION AND DO NOT SEE MUCH
HAPPENING WITH THAT TODAY. THUS...CLOUDY FOR MOST OF THE
DAY...THIS IS ESPECIALLY TRUE ACROSS THE SE CWA WHERE LOW LEVEL
MOISTURE WILL BE RICH/THICK ENOUGH FOR CLOUDS. NO PRECIPITATION
EXPECTED FOR THE DAY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 457 AM EST SAT DEC 21 2013
CURRENTLY...SPLIT FLOW IN THE UPPER LEVELS WITH A NRN STREAM JET
STREAK OVERHEAD...AND A SRN STREAM JET STREAK LIFTING INTO OK WHICH
IS EJECTED FROM A CUT OFF LOW OVER FAR WEST TX. IN THE NRN
STREAM...WE HAVE ONE WEAK AND SHEARED OUT VORT MAX RUNNING INTO
EASTERN LAKE SUPERIOR...WHICH HAS CONTINUED TO PRODUCE LIGHT
SNOW/FLURRY RETURNS ON MQT RADAR WHICH WERE WORKING UP THROUGH
WESTERN SECTIONS OF CHIP/MACK COUNTIES OF EASTERN UPPER. H8 LLJ
FORCING IS COMPLETELY DONE AS WIND DIRECTIONS HAVE VEERED WEST...AND
ACTUALLY DRYING WAS UNDERWAY FROM NORTH TO SOUTH. THIS ALSO HELPING
TO KEEP ANY LIGHT SNOW AT BAY ACROSS EASTERN UPPER. PECULIAR EARLIER
WEAK RADAR RETURNS EMANATING FROM ANTRIM INTO CRAWFORD COUNTY HAS
BEEN A VERY FINE LIGHT SNOW...AND THIS WAS ALSO ERODING...LIKELY DUE
TO THE NOW H8 DRYING. TOTAL MOISTURE IN THE COLUMN IS DRYING...AND
WILL NOW BE SLOWLY ERODING ANY CHANCE OF PRECIP AND PATCHY FREEZING
DRIZZLE...THE LATTER OF WHICH SEEMS TO BE ISOLATED AT BEST...WITH
ONLY CADILLAC OBSERVATION SUGGESTING THE POSSIBILITY OF FREEZING
DRIZZLE...AND ACTUALLY BELIEVE THAT IS MORE OF A LOWERING
CEILING/FREEZING FOG TYPE THING. DO NOT BELIEVE THAT THIS IS ANY
SERIOUS IMPACT.
TODAY AND TONIGHT...WEAK/SHEARED OUT VORT MAX WILL EXIT EAST OVER
THE NEXT COUPLE OF HOURS WITH H8 DRYING CONTINUING TO SLIDE
SOUTH...ENDING ALL LIGHT SNOW IN EASTERN UPPER. WINDS DO VEER MORE
NORTHERLY INTO THE DAYLIGHT HOURS...AND LOW LEVEL TEMPS RESULT IN
DELTA T`S SUFFICIENT ENOUGH FOR MAYBE A FEW FLURRIES ACROSS FAR NE
LOWER. OUTSIDE OF THAT...A QUIET PERIOD OF WEATHER FOR THE
DAY...WITH DEEP SW FLOW ALOFT...ABOVE THE SHALLOW COLDER AIR. THIS
WILL CONTINUE TO BRING IN MIDDLE AND UPPER LEVEL CLOUDS. DO NOT SEE
THE NORTHERLY FLOW BEING STRONG ENOUGH TO SCOUR OUT THE LOW LEVEL
CLOUDS ACROSS THE SE PART OF THE CWA. THIS WILL RESULT IN A RETURN A
DEEPLY SATURATED ATMOSPHERE IN THE AFTERNOON. WE WILL SEE SOME WEAK
ENERGY EJECTED FROM THE SRN STREAM CUT OFF WORKING IN OVER THE FAR
SE CWA LATE IN THE AFTERNOON FOR THE FIRST CHANCES FOR SEEING SOME
LIGHT SNOW FALL. STRONGER ENERGY/MODERATE DEEP LAYER -DIVQ ARRIVES
OVERNIGHT...AS THE ATMOSPHERE DEEPENS IN MOISTURE. THIS WILL MAINLY
BE ACROSS NRN LOWER. THE DEEP MOISTURE IS BROUGHT IN BY A WIDE OPEN
GULF (CURRENTLY STREAMING DEEP LOW LEVEL MOISTURE INTO THE OHIO
RIVER VALLEY) ARRIVES VIA STRONG LOW LEVEL JET. AS THE SRN STREAM
CUT OFF OPENS UP AND LIFTS INTO ILLINOIS LATE TONIGHT/DAYBREAK
TOMORROW...THE SFC LOW DEEPENS SOME...AND WINDS BACK...ALLOWING THE
BEST LOW LEVEL MOISTURE TURN GET LIFTED FURTHER NORTH INTO OUR NECK
OF THE WOODS. AT THE SAME TIME...STRONG DEEP LAYER -DIVQ IS SETTLED
IN ON US...AND SNOWS WILL PICK UP IN INTENSITY. CAN SEE AROUND A
COUPLE OF INCHES BY DAYBREAK ACROSS THE SE CWA...LESSENED NEAREST
THE SAG BAY BY LOW LIQUID-SNOW RATIOS AND THE POSSIBILITY (IF WARMER
NAM IS RIGHT) OF A MIX WITH SLEET.
FOR A DISCUSSION ON THE WATCH SITUATION...SEE BELOW.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 457 AM EST SAT DEC 21 2013
AN ACTIVE WEATHER PATTERN ALONG WITH COLD TEMPERATURES CONTINUE
THROUGH THE FORECAST PERIOD WITH A MEAN TROUGH REMAINING IN PLACE
ACROSS CENTRAL CANADA INTO THE GREAT LAKES REGION. IN
ADDITION...UPPER LEVEL DISTURBANCES MOVING THROUGH THE FLOW ALOFT
WILL BRING NUMEROUS CHANCES FOR SNOW SHOWERS...ENHANCED FROM TIME TO
TIME BY THE BIG LAKES. MEANWHILE...THE WELL ADVERTISED SOUTHERN JET
STREAM SYSTEM COULD STILL POTENTIALLY BRING WHAT LOOKS LIKE A
MODERATE AMOUNT OF SNOW TO REGION LATER SATURDAY NIGHT INTO SUNDAY.
THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND SNOW AMOUNTS FOR
SATURDAY NIGHT INTO SUNDAY THEN THE USUAL SUSPECTS...POPS AND
TEMPERATURES FOR THE REMAINDER OF THE FORECAST.
SUNDAY...SOUTHERN BRANCH ENERGY MOVES NORTHWARD ALONG A TIGHTENING
BAROCLINIC ZONE. LATEST MODEL RUNS CONTINUE TO HAVE A MODEST AREA OF
LOW PRESSURE AT THE SURFACE TRACKING ACROSS EITHER NORTHERN OHIO
(MAJORITY OF MODELS) OR SOUTHWEST LOWER MICHIGAN (INCONSISTENT AND
CONTINUED OUTLIER NAM). THERE IS STILL THE POTENTIAL FOR LAKE
ENHANCEMENT OFF OF LAKE HURON ACROSS NORTHEAST LOWER AS A POCKET OF
COLDER AIR (850 MB TEMPS -10 TO -12 C) TRIES TO SYNC UP WITH THE
TAIL END OF DEEP SYNOPTIC MOISTURE. OVERALL...A GENERAL LIGHT TO
MODERATE SNOWFALL IS STILL EXPECTED WITH STORM TOTAL AMOUNTS OF
BETWEEN 4 AND 8 INCHES OF GREASY SNOW WHICH WILL BE COVERED WITH A
WINTER WEATHER ADVISORY FOR ALL COUNTIES OF NORTHERN LOWER MICHIGAN.
WILL STILL HAVE TO BE COGNIZANT OF POSSIBLE SNEAKY LAKE ENHANCEMENT
ADDING TO THE TOTALS ACROSS NORTHEAST LOWER. MEANWHILE...ACROSS
EASTERN UPPER...2 TO 3 INCHES OF ACCUMULATION IS EXPECTED. HIGHS
RANGING FROM THE UPPER TEENS TO MIDDLE 20S...BUT LIKELY FALLING OFF
IN THE AFTERNOON AS COLD AIR ADVECTION KICKS IN.
SUNDAY NIGHT...WRAP AROUND MOISTURE/DEFORMATION ZONE AXIS SITS OVER
THE REGION. THIS WILL LIKELY BRING SOME LIGHT SNOW...WITH ADDITIONAL
ACCUMULATIONS OF ONE TO PERHAPS TWO INCHES. LOWS RANGING FROM THE
COLDER SINGLE DIGITS ABOVE ZERO TO THE MIDDLE TEENS.
MONDAY AND MONDAY NIGHT...A NORTHERN STREAM TROUGH ALONG WITH
ANOTHER SHOT OF ARCTIC AIR (850 MB TEMPS DOWN TO -20 C OR SO) DROPS
DOWN INTO THE REGION BRINGING ADDITIONAL CHANCES FOR MAINLY LIGHT
SNOW. THE FLOW IS RATHER LIGHT OVERALL BUT MAY STILL BE JUST STRONG
ENOUGH TO PRODUCE SOME LAKE EFFECT (GENERALLY OUT OF THE NORTH
NORTHWEST). HOWEVER...AM NOT EXPECTING BIG TIME ACCUMULATIONS WITH
MODEL SOUNDINGS SHOWING INVERSION HEIGHTS OF ONLY AROUND 3000 FEET
OR SO PLUS SNOWFLAKE SIZES WILL LIKELY BE RATHER SMALL. HIGHS MAINLY
IN THE TEENS. LOWS RANGING FROM THE COLDER SINGLE DIGITS TO THE
MIDDLE TEENS.
TUESDAY...PERHAPS SOME LINGERING NORTH NORTHWEST FLOW LAKE EFFECT IN
THE MORNING. OTHERWISE...ARCTIC HIGH PRESSURE PRESSES DOWN FROM THE
NORTH YIELDING VERY COLD TEMPERATURES AND PERHAPS CLEARING SKIES (IF
WE CAN SCOUR OUT THE LIKELY STUBBORN STRATUS). HIGHS ONLY EXPECTED
TO RANGE FROM THE UPPER SINGLE DIGITS (ABOVE ZERO) TO THE MIDDLE
TEENS. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO AT NIGHT.
WEDNESDAY THROUGH FRIDAY...A PARADE OF SHORT WAVES DROP DOWN THROUGH
THE FLOW. EXTENDED MODELS CONTINUE TO VARY ON THE EXACT TIMING AND
DETAILS SO WILL NOT GET TOO FANCY...AND HAVE GENERAL CHANCES FOR
SNOW SHOWERS. THERE COULD BE SOME LAKE ENHANCEMENT AS WELL FROM TIME
TO TIME...BUT PINNING DOWN THE EXACT FLOW REGIMES IS NEARLY
IMPOSSIBLE THIS FAR OUT. HIGHS IN THE MIDDLE TO UPPER 20S WEDNESDAY
THEN COOLING OFF AGAIN INTO THE UPPER TEENS TO MIDDLE 20S FOR
THURSDAY AND THE MIDDLE TEENS TO AROUND 20 FOR FRIDAY. LOWS IN THE
TEENS WEDNESDAY NIGHT THEN THE SINGLE DIGITS FOR THURSDAY AND FRIDAY
NIGHTS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 215 PM EST SAT DEC 21 2013
CIGS HAVE SLOWLY INCREASE ACROSS NRN LOWER MICHIGAN OVER THE LAST
FEW HOURS...WITH ALL TERMINAL SITES MVFR OR BETTER. CONDITIONS
WILL LARGELY REMAIN UNCHANGED THROUGH THIS EVENING. SNOWFALL WILL
BEGIN TO NUDGE INTO THE REGION SOUTH-NORTH LATE TONIGHT REACHING
THE TAF SITES BETWEEN 08Z AND 12Z. CIGS/VSBYS WILL LOWER TO LOW
MVFR OR IFR AND REMAIN THERE THROUGH MUCH OF SUNDAY.
LIGHT NORTHEASTERLY WINDS THROUGH THIS AFTERNOON. BUT NE-E WINDS
INCREASE TONIGHT AND BECOME A BIT GUSTY FOR SUNDAY (GUSTS INTO THE
20 TO 25 KNOT RANGE) AS LOW PRESSURE TRACKS BY TO OUR SOUTH.
&&
.MARINE...
ISSUED AT 457 AM EST SAT DEC 21 2013
A LIGHT EASTERLY WINDS REGIME WILL BRIEFLY TURN NORTHERLY OVER MANY
OF THE NEARSHORE WATERS THIS MORNING...BEFORE RETURNING TO EASTERLY
AND INCREASING THROUGH TONIGHT. THIS DUE TO STRENGTHENING LOW
PRESSURE THAT WILL LIFT THROUGH DETROIT. A PERIOD OF ADVISORY LEVEL
WINDS WILL DEVELOP TONIGHT...BEFORE DYING BACK OFF SUNDAY NIGHT INTO
MONDAY WITH THE APPROACH OF HIGHER PRESSURE. THESE LIGHTER WINDS
CONTINUE INTO TUESDAY.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 1 AM TO 7 PM EST SUNDAY FOR
MIZ016>036-041-042.
LH...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY
FOR LHZ345>349.
LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY
FOR LMZ323-341-342-344>346.
LS...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY
FOR LSZ321-322.
&&
$$
UPDATE...BA
SYNOPSIS...AS
SHORT TERM...SD
LONG TERM...AS
AVIATION...BA
MARINE...SD
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
105 PM EST SAT DEC 21 2013
LATEST UPDATE...
HYDRO
.SYNOPSIS...
ISSUED AT 1245 PM EST SAT DEC 21 2013
A STORM SYSTEM APPROACHING FROM THE SOUTHWEST WILL AFFECT THE AREA
WITH A VARIETY OF WINTER WEATHER BEGINNING THIS EVENING. SOUTH
CENTRAL LOWER MICHIGAN WILL LIKELY EXPERIENCE FREEZING RAIN AND
ICE ACCUMULATION WHERE TEMPERATURES SHOULD HOVER AROUND FREEZING.
FURTHER NORTH INTO CENTRAL LOWER MICHIGAN...THE PRECIPITATION TYPE
WILL TRANSITION TO A WINTRY MIX AND EVENTUALLY TO A HEAVY WET
SNOW.
WINTRY PRECIPITATION WILL TAPER OFF SUNDAY AFTERNOON AND EVENING.
MUCH COLDER AIR WILL FILTER IN BEHIND THE SYSTEM FOR AT LEAST
THROUGH CHRISTMAS DAY. SNOW WILL DEVELOP AGAIN LATE SUNDAY NIGHT AND
INTO MONDAY WITH THE POTENTIAL FOR SOME ACCUMULATIONS. THERE WILL
BE ADDITIONAL CHANCES FOR SNOW THROUGH THE WORK WEEK.
&&
.UPDATE...
ISSUED AT 945 AM EST SAT DEC 21 2013
DENSE FOG IS BECOMING AN INCREASING CONCERN THIS MORNING MAINLY
ALONG AND SOUTH OF AN EAST-WEST SURFACE BOUNDARY LOCATED JUST
NORTH OF I-94. THERE ARE MANY REPORTS OF VISIBILITY AT OR BELOW
1/4 MILE ALONG AND SOUTH OF THIS BOUNDARY. HRRR GUIDANCE PUSHES
THE BOUNDARY SOUTH OF THE FORECAST AREA BY THIS AFTERNOON WITH
INCREASING WINDS FROM THE NORTHEAST...SO EXPECT DENSE FOG TO BE
LESS OF A CONCERN BY AFTERNOON. WILL HIGHLIGHT THE ONGOING FOG
CONCERN IN AN UPCOMING WSW UPDATE.
RADAR SHOWS THAT PRECIPITATION HAS BEGUN TO OVERSPREAD THE AREA
SOUTHEAST OF A MARSHALL TO MASON LINE. WE ARE A LITTLE CONCERNED
ABOUT AIR TEMPERATURES STAYING SUFFICIENTLY COLD FOR ICE
ACCUMULATION IN THE WARNED AREA. TEMPERATURES AND DEWPOINTS ARE
VERY CLOSE TO FREEZING. A POSITIVE FOR FREEZING RAIN IS COLDER
AND SLIGHTLY DRIER AIR UPSTREAM TO THE NORTHEAST. ALSO SEVERAL
MESONET SITES IN THE AREA ARE REPORTED TEMPERATURES BELOW
FREEZING. CURRENT EXPECTATIONS ARE THAT ICE ACCUMULATION ON
SECONDARY ROADS AND EXPOSED ROAD SURFACES REMAIN A DEFINITE
CONCERN. WILL BE CLOSELY MONITORING TEMPERATURE TRENDS OVER THE
NEXT FEW HOURS.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 329 AM EST SAT DEC 21 2013
THE MAIN FOCUS OF THE SHORT TERM IS THE STORM SYSTEM EXPECTED TO
IMPACT THE AREA BEGINNING TODAY AND LASTING THROUGH SUNDAY. WE HAVE
TRANSITIONED THE HEADLINES FROM THE WATCH...TO AN ICE STORM WARNING
ACROSS THE FAR SE CORNER OF THE CWFA. ADVISORIES HAVE BEEN ISSUED
FOR THE REMAINDER OF THE CWFA FOR SNOW ACROSS THE NORTH AND A WINTRY
MIX ACROSS THE MIDDLE SECTION OF THE CWFA. NO MAJOR CHANGES IN THE
FCST HAVE BEEN MADE AS THE CONSENSUS OF THE MODELS IS GENERALLY
CONSISTENT WITH THE PREVIOUS RUNS.
WE WILL NEED TO DEAL WITH SOME FOG ISSUES ACROSS THE SOUTH THIS
MORNING.
THE GREATEST IMPACT OF THE INCOMING STORM SYSTEM LOOKS TO BE THE
THREAT OF RELATIVELY SIGNIFICANT AMOUNTS OF FREEZING RAIN/ICING
EXPECTED ROUGHLY SE OF I-69 LATER TODAY AND INTO THE EARLY OVERNIGHT
HOURS TONIGHT. WE EXPECT RAIN AND OR FREEZING RAIN TO START PUSHING
UP INTO THE SRN COUNTIES TOWARD THE AFTERNOON TODAY. AREAS ALONG AND
SOUTH OF I-94 COULD START OUT BARELY ABOVE FREEZING AT THE ONSET OF
PCPN. WE EXPECT ALL PCPN DOWN ACROSS THE SE CORNER TO TRANSITION TO
FREEZING RAIN AS THE COLD AND SOMEWHAT DRIER NE FLOW WILL BRING
TEMPS DOWN DUE TO ADVECTION AND EVAPORATIVE COOLING.
QPF ACROSS THE SE COUNTIES LOOKS TO BE OVER AN INCH THROUGH THE
EARLY OVERNIGHT HOURS AS THEY BARELY GET UNDER THE NRN PERIPHERY OF
THE BEST MOISTURE AXIS WITH THIS SYSTEM. AN ABOVE FREEZING LAYER
ALOFT IS MAINTAINED MOST OF THE TIME AS THE SFC TEMPS DROP TO AROUND
OR JUST BELOW FREEZING. NOT ALL OF THIS QPF WILL GO INTO THE ICING
EXPECTED DUE TO LATENT HEAT AND RUNOFF PROCESSES. HOWEVER WITH THAT
MUCH QPF...EVEN A PORTION OF IT FREEZING WILL CREATE A GOOD COATING
OF ICE...UP AROUND HALF AN INCH WILL BE LIKELY.
THE TRANSITION IN P-TYPE WILL BE SOMEWHAT TRICKY ACROSS THE CENTRAL
PORTION OF THE CWFA NW OF I-69 TO ROUGHLY M-20. HOWEVER WE EXPECT
THAT FREEZING RAIN AND SLEET TO BE MORE PREVAILING WITH SOME SNOW
POSSIBLE. A SLIGHT ABOVE FREEZING LAYER WILL BE PRESENT WITH THE
LAYER THINNER AND COOLER AS YOU MOVE NW. QPF AMOUNTS WILL BE QUITE A
BIT LESS AS THE MOISTURE AXIS REMAINS SE OF THIS AREA. IT WILL BE
TOUGH TO GET HIGH IMPACT FREEZING RAIN AMOUNTS IN THIS AREA. HOWEVER
ONE THING TO CONSIDER IS THE GLAZE IN PLACE ALREADY FROM THE THU
NIGHT/FRI EVENT.
THE PCPN IN BOTH OF THESE AREAS IS EXPECTED TO LIGHTEN UP
SIGNIFICANTLY BETWEEN 06-12Z SUN AS THE DRY SLOT IS EXPECTED TO MOVE
OVER THESE AREAS. SOME LIGHT PCPN WILL REMAIN...HOWEVER WE COULD
SEE IT TRANSITION TO FZDZ AS THE DGZ BECOMES UNSATURATED.
BY THE TIME PCPN REACHES THE NRN PORTION OF THE CWFA...THE COLUMN
SHOULD BE MAINLY COLD ENOUGH TO SUPPORT MAINLY SNOW. THE SNOW SHOULD
START OUT LIGHT...AND PICK UP LATE TONIGHT/SUN MORNING AS THE BEST
DEFORMATION SLIDES ACROSS THE NRN COUNTIES AND NW OF THE CWFA. SNOW
AMOUNTS ARE GENERALLY EXPECTED TO REMAIN IN THE ADVISORY CATEGORY AS
THE UPPER LOW EJECTING WILL HAVE OPENED UP BY THE TIME IT REACHES
HERE AND THE FGEN IN THE DEFORMATION WILL NOT BE AS STRONG AS TO OUR
SW. ONE THING GOING FOR BETTER SNOW AMOUNTS HERE IS THE FACT THAT
THE DGZ IS EXPECTED TO REMAIN SATURATED AS THE DRY SLOT REMAINS SE
OF THIS AREA.
THE CAVEAT TO ALL OF THIS IS IF THE OUTLIER NAM IS CORRECT...ALL OF
THIS WOULD BE SHIFTING TO THE NW A LITTLE. WE BELIEVE AT THIS TIME
THAT WE HAVE A GOOD CONSENSUS OF THE TRACK OF THE SYSTEM WITH GOOD
RUN TO RUN CONSISTENCY FROM MOST OF THE GLOBAL MODELS AND IT SHOULD
BE WELL SAMPLED BY NOW WITH IT BEING WELL WITHIN THE RAOB NETWORK.
WE WILL SEE A TRANSITION TO SOME LAKE EFFECT SNOW SHOWERS ON SUN
NIGHT AS COLDER AIR COMES IN BEHIND THE SYSTEM. THE FLOW SHOULD BE
NNW WHICH WOULD FAVOR THE IMMEDIATE LAKESHORE FOR BEST SNOW SHOWER
CHANCES. THERE IS SOME DECENT MOISTURE UP THROUGH 15K FEET AND
OVER-LAKE INSTABILITY IS SUFFICIENT.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 329 AM EST SAT DEC 21 2013
THE UPCOMING CHRISTMAS WEEK WILL BE MORE LIKE WHAT WE HAVE SEEN FOR
MUCH OF DECEMBER: COLDER THAN NORMAL WITH FREQUENT CHANCES FOR SNOW
SHOWERS. THE NORTHERN BRANCH OF THE JET AND ARCTIC AIR WILL DOMINATE
THROUGHOUT THE WEEK... WITH SEVERAL SHORTWAVES AND SFC
TROUGHS/FRONTS SWINGING THROUGH THE GRTLKS RGN. TEMPERATURES ARE
EXPECTED BE BELOW FREEZING ALL WEEK... AND THE COLDEST DAY OF THE
WEEK WILL BE TUESDAY WHEN HIGHS SHOULD STRUGGLE TO REACH 20 BEHIND
THE FIRST NRN STREAM WAVE.
GFS/ECMWF ARE IN GOOD AGREEMENT SHOWING A POTENT SHORTWAVE IMPACTING
THE AREA MONDAY AFTERNOON AND NIGHT. SNOW SHOWERS ARE LIKELY AND
LAKE ENHANCEMENT WILL BE IN PLAY AS THIS FEATURE COMES THROUGH.
HOWEVER CONFIDENCE IN WIND DIRECTION IS LOW SINCE MODELS INDICATE A
WEST TO EAST ORIENTED SFC TROUGH SETTING UP SOMEWHERE ACROSS LWR MI
AND ARE NOT IN GREAT AGREEMENT WITH IT/S LOCATION AND RESULTANT
WINDS. NEVERTHELESS THE TROUGH SHOULD RESULT IN LOCALLY ENHANCED
CONVERGENCE WITH A LARGE PORTION OF THE CWFA SEEING SNOW SHOWERS AND
AT LEAST SOME LIGHT ACCUMULATIONS. IF A WESTERLY FLOW DEVELOPS THEN
AREAS ALONG AND WEST OF HWY 131 COULD SEE SEVERAL INCHES BUT AGAIN
WIND DIRECTION IS VERY QUESTIONABLE AT THIS TIME.
A BRIEF PERIOD OF SHORTWAVE RIDGING MOVES ACROSS FOR TUESDAY
AFTERNOON AND EVENING... THEN SOME WAA/ISENTROPIC LIFT LIGHT SNOW
POSSIBLE ON CHRISTMAS DAY AHEAD OF THE NEXT APPROACHING SHORTWAVE.
THE ECMWF HAS A MUCH STRONGER SHORTWAVE THAN THE GFS FOR THE 26TH
AND WOULD SUGGEST A DECENT ROUND OF ACCUMULATING LAKE ENHANCED SNOW
SHOWERS FOR THURSDAY AND THURSDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1258 PM EST SAT DEC 21 2013
WIDESPREAD LIFR ACROSS THE REGION THIS AFTERNOON. NOT EXPECTING
MUCH OVERALL CHANGE OVER THE NEXT 24 HOURS. THE DIFFICULT ASPECT
OF THE FORECAST IS DETERMINING WHEN PCPN WILL OCCUR AT THE TAF
SITES AND WHAT TYPE OF PCPN WILL FALL.
RATHER THAN A LONG DURATION OF PCPN...IT APPEARS WE WILL SEE A
PERIOD OF PCPN THIS EVENING...THEN AS A DRY SLOT COMES IN...THE
PCPN MAY END FOR A BIT OVERNIGHT...THEN ANOTHER PERIOD OF PCPN
SHOULD OCCUR FOR MUCH OF SUN MORNING.
AS FOR PCPN TYPE...THE RAIN TO WINTRY MIX LINE RAN FROM NEAR BIV
TO TEW AT 17Z. THIS APPEARS TO CHANGE LITTLE INTO TONIGHT...WHICH
MEANS THE I-94 TAF SITE SHOULD REMAIN RIGHT ON THE EDGE OF THE
ICY PCPN. HAVE GONE MORE OPTIMISTIC WITH LIQUID PCPN AT THE I-94
TAF SITES...BUT THIS IS A VERY CLOSE CALL...AND WE WILL CONTINUE
TO MONITOR.
MEANWHILE THE I-96 TAF SITES CAN CONTINUE TO EXPECT PERIODS OF
FREEZING RAIN WHICH SHOULD BEGIN TO SWITCH TO SNOW AND/OR SLEET
MID/LATE SUNDAY MORNING.
&&
.MARINE...
ISSUED AT 534 PM EST FRI DEC 20 2013
NORTHEAST FLOW WILL CONTINUE INTO SATURDAY NIGHT. THIS OFFSHORE FLOW
WILL HELP KEEP WAVES LOWER. HOWEVER AS WINDS PIVOT TO THE NORTH
NORTHWEST LATE SATURDAY NIGHT/EARLY SUNDAY MORNING WAVES WILL BUILD
AND WE WILL LIKELY NEED A SMALL CRAFT ADVISORY BY THEN.
&&
.HYDROLOGY...
ISSUED AT 103 PM EST SAT DEC 21 2013
THE HEADWATERS OF THE GRAND AND ST. JOSEPH RIVER BASINS ARE EXPECTED
TO RECEIVE AROUND 0.75 INCHES OR LESS WITH THIS EVENT. BEST CHANCE
FOR FLOODING REMAINS TO THE SOUTH IN NORTHERN INDIANA AND NORTHWEST
OHIO. A SHARP RISE BELOW FLOOD STAGE OF THE GRAND RIVER AT JACKSON
IS EXPECTED...BUT THIS RISE WILL BE BRIEF AND SHOULD FALL QUICKLY.
STORM EVOLUTION WILL BE MONITORED CLOSELY FOR HEAVIER PRECIP AMOUNTS
OVER THE GRAND HEADWATERS.
TEMPERATURES ARE HOVERING NEAR FREEZING TODAY. SNOW MELT COULD
CONTRIBUTE TO RISES AS WELL. ICE BREAKUP AND MOVEMENT COULD CAUSE
RIVER RISES ON SUNDAY WITH TEMPS REACHING THE UPPER 30S IN SOUTH
CENTRAL LOWER MICHIGAN.
ARCTIC AIR STREAMS BACK IN ON SUNDAY NIGHT. MONDAY NIGHT AND TUESDAY
NIGHT ARE EXPECTED TO BE VERY COLD...WITH LOWS IN THE SINGLE DIGITS
POSSIBLE. ICE DEVELOPMENT ON RIVERS IS EXPECTED...SO THE RISK FOR
ICE JAM FLOODING INCREASES. TEMPS WILL STAY BELOW FREEZING THROUGH
ALL OF NEXT WEEK.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR MIZ051-052-
056>059-064-065-071-072.
ICE STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ066-067-073-074.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST
SUNDAY FOR MIZ037>040-043>046-050.
LM...NONE.
&&
$$
UPDATE...TJT
SYNOPSIS...JAM
SHORT TERM...NJJ
LONG TERM...MEADE
AVIATION...JK
HYDROLOGY...EBW
MARINE...JK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1254 PM EST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 457 AM EST SAT DEC 21 2013
SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN
STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES
ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT
LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW
WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA
UNTIL DAYBREAK ON SUNDAY.
EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN
LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF
ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK
SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT
SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF
OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW
TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP
TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO
THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC
TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT.
EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY
GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE
OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR
REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED
LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO
5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE
AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT
SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT
WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW
TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS.
CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE
THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS
ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS.
THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN
KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS
AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT
EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4
INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE
MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS
ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF
SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN.
ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1
INCH.
MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH
EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL
MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM
TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER
MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY
PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS
TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES
MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS
INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK
SUPERIOR.
SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON
THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF
LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85
AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF
WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING
WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR
SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE
INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL
CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS
MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS
THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS
WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR
SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE
EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE
SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 457 AM EST SAT DEC 21 2013
HAVE OPTED TO ISSUE A WINTER STORM WATCH FOR THE TERRAIN/LAKE
ENHANCED AREAS OF MARQUETTE/BARAGA COUNTIES AS WELL AS GOGEBIC AND
ONTONAGON COUNTIES FOR SUNDAY AND MONDAY. LONG DURATION LAKE
ENHANCED/LAKE EFFECT SNOW EPISODE LOOKING MORE POSSIBLE NOW AS THE
MODELS ARE STARTING TO COME INTO BETTER AGREEMENT INTO A MAIN LOW
TRACK THROUGH SOUTHERN MI ON SUNDAY. HOWEVER...THE COMPLEX
INTERACTION BETWEEN THE SOUTHERN STREAM ENERGY MOVING THROUGH THE
LOWER LAKES AND THE NORTHERN STREAM TROUGH MOVING INTO THE UPPER
MIDWEST MAKES THIS FORECAST CONFIDENCE STILL SOMEWHAT BELOW AVERAGE.
ONTO THE DETAILS...AS SAID ABOVE THE NWP SUITE HAVE COME INTO BETTER
AGREEMENT WITH THE MAIN LOW MOVING THROUGH SOUTHERN LOWER MICHIGAN
WITH THE SOUTHERN STREAM IMPULSE MOVING OUT OF THE PLAINS. EXPECT
SYNOPTIC MOISTURE AND LIFT TO GLANCE BY THE SOUTHEAST FORECAST AREA
SUNDAY MORNING INTO EARLY AFTERNOON AS THE COMMA HEAD/DEFORMATION
ZONE PCPN MOVES THROUGH. THIS TRACK WILL ALLOW FOR 1000-850MB WINDS
TO TURN NE AND SHOULD ALLOW FOR LAKE ENHANCEMENT TO ALSO DEVELOP IN
MARQUETTE/BARAGA COUNTIES AS WELL AS THE FAR WEST NEAR IRONWOOD.
CONSENSUS QPF FROM THE NWP SUGGEST ABOUT 0.20-0.30 INCH OF QPF NEAR
LAKE MICHIGAN AND FAR EAST ON SUNDAY...WITH MUCH LESSER AMOUNTS WELL
INLAND AWAY FROM FROM LAKE SUPERIOR. THIS ALSO SEEMS REASONABLE
GIVEN THAT 700MB MIXING RATIOS REMAIN AROUND 2 G/KG THROUGH EARLY
AFTERNOON. GIVEN THAT SOME OF THE LIFT WILL BE IN THE DGZ AREA
ACROSS THE SOUTH DURING THE DAY...WE SHOULD SEE SNOW RATIOS ACROSS
THE FAR SOUTHEAST AROUND 15-17:1 DURING THE DAY WHICH WOULD EQUATE
TO 3-5 INCHES OF SNOW BY EVENING. MOST LIKELY AN ADVISORY WILL BE
NEEDED IN THIS AREA ON SUNDAY...BUT WILL HOLD OFF SINCE THIS WILL BE
GENERALLY A 3RD PERIOD ADVY.
AS FOR AREAS CLOSER TO LAKE SUPERIOR...ALL OF THE NWP GUIDANCE SHOW
PBL WINDS STAYING NELY THROUGH THE DAY WHICH SHOULD ALLOW FOR
TERRAIN ENHANCED SNOW TO COMMENCE IN THE NE FLOW FAVORED AREAS
DESPITE THE RELATIVELY WEAK SYNOPTIC LIFT. WITH THE BEST LIFT BEING
CONFINED TO GENERALLY BELOW THE DGZ...EXPECT SNOW RATIOS BE BE
FAIRLY LOW WITH ONLY AROUND 13:1. WILL GENERALLY GO WITH 4 OR 5
INCHES AT MOST IN THESE AREAS...BUT GIVEN THE STRONG AND DEEP NE
FLOW...WOULD NOT BE SHOCKED IF QPF AND THUS SNOWFALL IS MORE ON
SUNDAY.
THEN ON SUNDAY NIGHT...DIFFERENCE START TO DEVELOP WITH THE MODELS
REGARDING THE EVOLUTION OF THE NORTHERN STREAM UPPER TROUGH. THE NAM
IS CERTAINLY THE MOST AGGRESSIVE IN CLOSING OFF THE LOW AND
SETTLING OVER THE UPPER GREAT LAKES...WHICH ALLOW FOR A STRONG
INVERTED TROUGH TO HANG BACK ACROSS THE CENTRAL GREAT LAKES THROUGH
MONDAY. MEANWHILE...THE GFS GENERALLY KEEPS THE UPPER TROUGH OPEN
AND MOVES IN THROUGH THE AREA BY MONDAY AFTERNOON. THE LATEST 00Z
ECMWF IS INTERESTING AS IT ALSO ATTEMPT TO CLOSE OFF THE LOW SUN
NIGHT BUT IS NOT NEARLY AS DEEP AS THE NAM FORECASTS.
NONETHELESS...THE ECMWF ALSO SUGGESTS THAT THERE WILL BE SOME TYPE
OF INVERTED TROUGH EXTENDING BACK INTO THE AREA THROUGH MONDAY AND
OUR LOCALLY PRODUCE ARW-WRF USING THE GFS AS BOUNDARY CONDITIONS
ALSO SUGGEST THAT THERE WILL BE A INVERTED TROUGH HANGING BACK
THROUGH MONDAY. AS SUCH...DO NOT THINK THE PBL WINDS WILL SHIFT TO
N-NW AS FAST AS THE GFS AND ECMWF SUGGEST. IN FACT...THE CURRENT
THINKING IS THAT THE WINDS WILL STAY NORTHERLY OR PERHAPS A LITTLE
EAST OF NORTH THROUGH MONDAY WITH THIS TROUGH STAYING SOUTH OF THE
AREA. WITH ALL OF THIS SAID...THE EXPECTATION IS THAT THE SNOW WILL
TRANSITION TO MORE LAKE ENHANCED VARIETY AND PERSIST RIGHT THROUGH
MONDAY BEFORE THE UPPER TROUGH SWINGS THROUGH AND ALLOWS THE WIND TO
GRADUALLY SHIFT TO THE N-NW BY MON EVENING. AS SUCH...EXPECT
MODERATE TO LOCALLY HEAVY SNOW TO CONTINUE IN MQT/BARAGA COUNTIES AS
WELL AS GOGEBIC COUNTY THROUGH THE NIGHT SUNDAY INTO MONDAY. THE
BEST LIFT RAPIDLY BECOMING ENTRENCHED IN THE DGZ SUNDAY EVENING AS
THE UPPER TEMPS DROP...EXPECT THE SNOW TO BECOME MUCH MORE FLUFFY
BUT ALSO ACCUMULATE MUCH FASTER WITH RATIOS CLOSE TO 25:1 BY MON
MORNING. SOME AREAS IN THE WATCH AREA COULD SEE ANOTHER 8-12 INCHES
OF SNOW SUN NIGHT INTO MONDAY.
INTERESTINGLY...THERE ARE SEVERAL VERY GOOD CIPS ANALOG EVENTS FOR
THIS SYSTEM. THEY ALL GENERALLY SHOW THE WATCH AREA SEEING
SIGNIFICANT 72 HOUR SNOWFALL. NOT SURE IF WE WILL SEE ANY LONGER
PERIOD OF HEAVY SNOWFALL...RATHER I AM THINKING THAT IT WILL BE
GENERALLY A PERSISTENT SNOWFALL FOR 24-36 HOURS WHICH WILL ALLOW
WARNING CRITERIA TO BE REACHED. EVEN MORE INTERESTING...DESPITE THE
FACT THAT GOGEBIC COUNTY WILL BE FURTHEST REMOVED FROM THE
SYSTEM...THE CURRENT NWP AND ALSO THE CIPS GUIDANCE SUGGEST THAT
THIS AREA COULD SEE THE MOST SNOWFALL OUT OF THIS EVENT. WE WILL
SEE...
ANY REMAINING LES SHOULD END RAPIDLY MON NIGHT/TUE MORNING AS THE
HIGH PRES RIDGE BUILDS ACROSS THE FORECAST AREA. STILL LOOKS QUITE
COLD TUE MORNING ACROSS THE WEST WITH LIGHT WINDS/CLEAR SKIES. TEMPS
10-20 BELOW NOT OUT OF THE QUESTION IN THE NORMALLY COLDER SPOTS.
THE ECMWF AND GEM ARE IN GOOD AGREEMENT IN LIGHT OVERRUNNING/WARM
ADVECTION SNOW CHRISTMAS EVE NIGHT INTO CHRISTMAS DAY ACROSS THE
ENTIRE FORECAST AREA. SOME HINTS THAT THERE MIGHT BE SOME LAKE
ENHANCEMENT OFF OF LAKE MICHIGAN TUESDAY NIGHT AND HAVE OPTED TO
CONTINUE LIKELY POPS ACROSS THE EASTERN PART OF THE FORECAST AREA
TUE NIGHT INTO CHRISTMAS DAY. SOME DIFFERENCES EMERGE THU INTO
FRIDAY REGARDING THE EVOLUTION AND THE TROUGH WITH THE ECMWF BEING
DEEPER AND FURTHER SOUTH COMPARED TO THE GFS. REGARDLESS...SENSIBLE
WEATHER SHOULD GENERALLY THE SAME WITH EITHER MODEL WITH LES IN THE
NW FAVORED SNOWBELTS CHRISTMAS NIGHT INTO THU NIGHT BEFORE
DIMINISHING ON FRIDAY AS HIGH PRES BUILDS OVERHEAD. TEMPS STILL LOOK
BELOW NORMAL THROUGH THE EXTENDED WITH 850MB TEMPS -20 TO -25C WED
NIGHT/THU WARMING TO -15 TO -20C BY FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1243 PM EST SAT DEC 21 2013
KIWD...LIGHT WINDS BECOMING ONSHORE NE DIRECTION SHOULD ENSURE MVFR
CIGS AND LIGHT LAKE SNOW SHOWERS ACROSS THE TAF SITES BY LATE THIS
AFTERNOON. IFR VSBY IN SNOW AND BLSN IS EXPECTED TO DEVELOP AT WRN
TAF SITES LATE TONIGHT ESPECIALLY AS NE WINDS AND INSTABILITY
INCREASES OVER WRN LAKE SUPERIOR. WINDS BECOMING MORE EASTERLY WILL
SCATTER OUT THE LOW CLOUDS AT SAW LATE TONIGHT. WIDESPREAD SNOW IS
EXPECTED TO IMPACT ALL TERMINALS ON SUNDAY AS A LOW PRESSURE SYSTEM
SLIDES ACROSS THE CENTRAL GREAT LAKES REGION. HEAVIEST SNOW WILL
OCCUR AT IWD WITH UPSLOPE NORTHEAST WINDS PROVIDING ADDITIONAL
SUPPORT FOR SNOW OFF LK SUPERIOR. AS A RESULT...VSBYS AT KIWD COULD
LOWER TO LIFR BY LATE SUNDAY MORNING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 457 AM EST SAT DEC 21 2013
LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS
SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS
OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW
PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER
THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW
PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE
FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE
UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH
PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A
LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES.
THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE
SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON
WEDNESDAY...WINDS WILL BECOME WESTERLY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING
FOR MIZ002-004-005-009.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...MRD
AVIATION...VOSS
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DULUTH MN
341 PM CST SAT DEC 21 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 330 PM CST SAT DEC 21 2013
AT 330 PM...IT WAS FAIRLY QUIET ACROSS THE NORTHLAND. THERE
CONTINUED TO BE FLURRIES AND ISOLATED SNOW SHOWERS FOR MOST AREAS.
THE EXCEPTION WAS ALONG THE NORTH SHORE OF LAKE SUPERIOR...WHERE
AN INCH OF SNOW FELL THIS AFTERNOON IN COASTAL LAKE AND COOK
COUNTIES. TEMPERATURES RANGED FROM THE SINGLE DIGITS AT
INTERNATIONAL FALLS TO THE 20S IN NORTHWESTERN WISCONSIN.
THE HIGH RESOLUTION MODEL DATA INDICATES THAT THERE WILL BE
PERIODS OF LAKE EFFECT SNOW CONTINUING ACROSS WESTERN LAKE
SUPERIOR TONIGHT. THE HRRR AND WRF INDICATE A CONVERGENT BAND OF
SNOW ACROSS THE WESTERN PORTION OF THE LAKE...WITH SEVERAL WAVES
IN THE LINE. THIS WILL RESULT IN LOCAL SWIRLS AND CONSIDERABLE
VARIABILITY TO THE LAKE EFFECT OVERNIGHT. STRONG NORTHEAST WINDS
AT ROCK OF AGES CONTINUED ON ONE SIDE OF THIS BAND...WITH GUSTY
SOUTHERLY WINDS AT DEVILS ISLAND ON THE OTHER SIDE.
WINDS WILL OVERWHELMINGLY BECOME NORTHEAST TO NORTH OVERNIGHT AND
ON SUNDAY...WHILE THE OTHER SYSTEM MOVES IN FROM THE WEST. THE
RESULT WILL BE A PHASING OF THE MOISTURE ACROSS THE WESTERN GREAT
LAKES. OVERALL LOOKING FOR AN INCH OR TWO FOR MUCH OF THE AREA
TONIGHT...AND ANOTHER INCH OR TWO ON SUNDAY.
THE EXCEPTION WILL BE ACROSS THE SOUTH SHORE OF LAKE SUPERIOR. WE
COULD HAVE HANDLED THIS EVENT IN A COUPLE WAYS REGARDING HEADLINES
BUT AFTER EXTENSIVE DISCUSSION...WE DECIDED TO ISSUE A LAKE EFFECT
SNOW ADVISORY FOR THE PERIOD TONIGHT THROUGH MONDAY...RATHER THAN
HAVING A LARGE LAKE EFFECT SNOW WARNING OUT FOR 5 PERIODS...WITH
GENERALLY ADVISORY TYPE SNOW FOR MOST OF THE PERIODS. THINK THERE
IS A FAIR CHANCE WE MAY NEED TO UPGRADE TO A WARNING FOR MONDAY.
BUT FOR TONIGHT AND SUNDAY...WE ARE LOOKING AT TRANSITIONAL LAKE
EFFECT SNOWFALL BANDS...SWIRLS AND CONVERGENCE BANDS...AND THE
RESULT SHOULD BE WIDESPREAD ADVISORY TYPE SNOW.
WE ALSO COULD HAVE ISSUED THE ADVISORY FOR TONIGHT THROUGH SUNDAY
NIGHT...AND MAINTAINED THE WATCH FOR MONDAY...BUT FOR SIMPLICITY
SAKE...DECIDED TO HOLD OFF ON THAT FOR NOW. THE MAIN FOCUS FOR A
POTENTIAL WARNING ON MONDAY WOULD BE THE GOGEBIC RANGE. WE DO
AGREE THAT ADDED UP OVER 4-5 PERIODS...THE AMOUNTS COULD BE
IMPRESSIVE...SOME ON THE ORDER OF A FOOT OR MORE IN THE GOGEBIC
RANGE.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 PM CST SAT DEC 21 2013
FIRST CONCERN IN EXTENDED IS ON LONG DURATION LAKE EFFECT SNOW THAT
WILL PERSIST THROUGH MONDAY EVENING. THE 12Z RUNS OF THE
GFS/ECM/NAM ARE IN AGREEMENT THAT THE H85-H50 TROUGH AXIS PASSES
OVER WRN LAKE SUPERIOR DURING THE DAY MONDAY...BRINGING A STRONG
PUSH OF CAA WITH H85 TEMPS FALLING INTO THE NEGATIVE 20S AND
BOUNDARY LAYER WINDS BACKING OUT OF THE NORTH THEN NORTHWEST.
ALTHOUGH CONDITIONS REMAIN FAVORABLE FOR A FEW INCHES OF LIGHT SNOW
ALONG THE SOUTH SHORE OF LAKE SUPERIOR SUN NIGHT...LAPSE
RATES/INVERSION HTS SIGNIFICANTLY INCREASE MONDAY DUE TO THE ARRIVAL
OF THE COLD AIR. HAVE INCREASED QPF/SN AMOUNTS MONDAY TO ACCOUNT
FOR THE HIGHER INSTABILITY.
FOCUS TURNS TO ELONGATED VORT MAX THAT DROPS OUT OF CANADA AND
ACROSS THE NRN PLAINS TUESDAY/WEDNESDAY. LATEST ECM/GFS BOTH
SUGGEST THE DIGGING WAVE...WITH SFC REFLECTION COLD FRONT...SWEEPS
ACROSS THE NORTHLAND DURING THE CHRISTMAS HOLIDAY. CURRENT TIMING
WOULD FAVOR A FEW INCHES OF SNOW OVER MUCH OF THE REGION TUESDAY
NIGHT. HOWEVER...IF TIMING SLOWS...ITS POSSIBLE THE COLD FRONT/LIGHT
SNOW HOLD OFF UNTIL CHRISTMAS DAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1230 PM CST SAT DEC 21 2013
MAINLY MVFR CEILINGS AND LIGHT FLURRIES WILL BE FOUND TODAY WITH
POCKETS OF CLEARING. MVFR CEILINGS WILL AGAIN INCREASE IN COVERAGE
OVERNIGHT AS LIGHT SNOW DEVELOPS ACROSS THE AREA SUNDAY MORNING.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 8 13 -8 1 / 70 90 70 20
INL -9 2 -20 -5 / 40 50 20 10
BRD 4 11 -13 -2 / 70 90 50 10
HYR 11 21 1 6 / 60 90 80 70
ASX 15 21 9 9 / 70 90 90 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...LAKE EFFECT SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST
MONDAY FOR WIZ001>004.
LS...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 AM CST MONDAY
FOR LSZ121-140>148.
&&
$$
SHORT TERM...DAP
LONG TERM...GRANING
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1154 AM CST Sat Dec 21 2013
.UPDATE...
Issued at 1152 AM CST SAT DEC 21 2013
No significant changes have been made to the forecast thinking. The
past few hours have seen a relative lull in precipitation, however
freezing rain and sleet appears to be rapidly filling back in across
eastern KS and western MO in an area of increasing isentropic ascent.
Precipitation will likely continue to expand through mid afternoon
across areas near and south of the Highway 36 corridor. Thermal
profiles suggest most of this precip will take the form of sleet or a
sleet/freezing rain mix along and north of a Kansas City to Macon
line, with mostly freezing rain to the south. Could see additional
ice accumulations around a tenth of an inch for the
Butler/Sedalia/Boonville areas through sunset with local amounts up
to two tenths of an inch. Further north across the KC to Moberly
corridor there will likely be a thin glazing of ice with minor (1/4"
or less) accumulations of sleet. Higher threat for icing will be
south of the Missouri River with more sleet to the north.
Later tonight all models continue to point to several inches of
accumulating snow occurring from the KC and STJ areas northeast toward
Kirksville. The NAM in particular is supportive of a frontogenetical
band of heavy snow developing somewhere between Kansas City and St.
Joseph that could provide enhanced snowfall rates up to 2" per hour
and possibly thunder. However other models including the RAP are less
suggestive of this and differ substantially with where such a band
would set up. For now no major changes are being made to snow totals
tonight, with a band of 5"+ snows setting up near and just north of
the KC/Kirksville corridor. If frontogenetical forcing does begin to
dominate later this evening, then there could be some enhanced snow
amounts around 8" somewhere near St. Joseph or Kansas City with a
sharper gradient between areas that receive heavy snow and areas that
see little snowfall.
&&
.SHORT TERM...(Today through Sunday Night)
Issued at 353 AM CST SAT DEC 21 2013
Early morning water vapor imagery shows an impressive plume of Pacific
moisture spreading across the central CONUS ahead of a deep upper
trough centered over the northern Chihuahua state of Mexico. Precipitation
has broken out in earnest since mid afternoon from Oklahoma into the
Ozarks, and the anticipated northward shift of this moisture and the
arrival of the upper low tonight remain the primary forecast concerns
through the next 24 hours.
TODAY
------
IMPACTS: Minor ice accumulations generally along and south of
a Kansas City to Moberly line -- highest mid Missouri southward.
Regional radar imagery mimics the inherited forecast rather well. As
expected, precipitation has had difficulties gaining latitude north
of I-44, owing to persistent warm advection from eastern OK into nrn
AR along the nose of a 60+ knot low level jet, yielding a broken arc
of thunderstorms and substantial trailing stratiform region from
central OK into srn MO. Meanwhile, isentropic downglide continues to
erode at northward precipitation advances, with a considerable dry
layer still present between the low stratus and the Pacific moist
plume aloft. A few pockets of freezing rain have reached the far srn
CWA (Clinton-Sedalia-Boonville) early this morning, but impacts have
been minimal. We`ve also received some sleet reports which were
puzzling given the +6 to +8C warm nose aloft at 800mb, but a more in-depth
look at soundings shows that 925mb temps bottom at -8 to -10C, enough
to refreeze some of those rain drops. That cold layer is expected to
moderate some this morning, keeping most of the precip as FZRA.
Although low level flow trajectories are currently from the SW,
keeping most of the precip over OK/AR/srn MO, I anticipate that the
flow will back this morning as the upper trough begins to lift across
the TX/MX border and become negative tilt. This , coupled with
increasing large scale ascent, should allow a net northward
transport of the steadier precipitation into the forecast area
before daybreak and continuing throughout the day. Heavier
precipitation should remain focused just southeast of the CWA border
from Springfield-Columbia-St. Louis and points south. Travel down
toward the I-44 corridor is *highly* discouraged. Locally, freezing
rain (possibly mixed sleet north and west) will result in minor ice
accretion of a few hundredths to around a tenth of an inch, with the
exception of Clinton-Sedalia-Boonville where up to a third of an inch
of icing is possible. Maintenance of northerly low level ageostrophic
flow should keep temperatures below freezing throughout the day.
TONIGHT:
--------
IMPACTS: Light icing will diminish eastern areas this evening. Rapid
snow accumulations become the main concern across portions of northwest
and north central Missouri from sundown through 6 AM.
Once again, the forecast is anything but a slam dunk with a rather
sharp snow gradient anticipated across the CWA. Conveying this
message to partners and customers may be more challenging than the
forecast itself, as there will likely be close proximity between the
haves and have nots when all is said and done.
As the upper low matures on its approach early this evening, column
saturation will occur quickly over NW MO with temperature profiles
rapidly cooling below freezing. Models remain consistent with taking
the core of the mid level center across Kansas City to Kirksville
between 06 and 09Z, with deformation of the mid level frontal zone
yielding rather prolific snowfall rates in a 100 mile zone northwest
of the center track. Despite the fast system speed and an increasingly
disconnected warm conveyor source region, cross-sections show
vigorous ascent (30+ ubar/s) associated with strong mid-level
frontogenesis within the optimal -12 to -18C dendritic growth region.
This should yield a quick 4 to 7" snowfall in meso-alpha scale band.
While the placement of highest snow accumulations and amounts have not
changed, the forecast gets rather dicey east of a Kansas City to
Kirksville line. Although not well handled in most of the model
output, it would seem to reason that narrow dry slot would develop
given a system of this strength/maturity, and punch east of the mid
level low center during the evening as the cyclone reaches maturity.
If this occurs, snowfall accumulations over the eastern CWA may be
significantly reduced if not eliminated as ice nuclei are scoured.
Even a slight shift in the cyclone track could mean the difference
between a location receiving plowable snows and potentially a non-
event. This gradient may perhaps exist across the KC metro itself, so
we will need to remain focused on this message until the deformation
zone becomes clear by late afternoon to our SW.
The upper low should continue to accelerate NE after midnight, and
most of the accumulating snowfall will shift north of the Iowa border
by 12Z. The next shift may want to consider trimming the winter storm
warning end time back to around 12Z.
SUNDAY/SUNDAY NIGHT:
--------------------
IMPACTS: Bitter cold.
Cloudy and somewhat blustery conditions expected. Temperatures will
barely reach the mid 20s, with wind chills in the teens.
With the passage of the longwave mid level trough axis Sunday
evening, low level flow will turn anti-cyclonic. The leading edge of
stronger gradient flow, associated with a surge of low level arctic
air, will push into the CWA by early evening as skies gradually
clear. Some areas could see the coldest lows of the season given the
magnitude of this airmass coupled with fresh snow cover.
Bookbinder
.LONG TERM...(Monday through Friday)
Issued at 353 AM CST SAT DEC 21 2013
Beginning of the work week continues to look cold as the large scale
trough that helped bring the weekends winter weather will still be
in place across the Plains States. This will allow a surge of cold
air to spread across the central Plains Sunday night through Monday
night. Advertisements from the models indicate the 850mb
temperatures in the -10C to -15C range will move south with a
1037mb surface high. This will keep temperatures in the teens --if
not colder-- for Monday`s high with early morning lows Tuesday
ranging below zero in all areas north of the Missouri River. Given
the current forecast, any light wind Tuesday morning will result in
dangerously cold wind chill values. However, later Tuesday the
center of the cold surface high will slide to our east, moderating
our temperatures as we move forward through the week. This should
allow temperatures to creep back into the 20s and 30s for Christmas
day. A few of the medium range models indicate that another
shortwave trough swinging through the northern Plains into the Great
Lakes may induce a bit of light precipitation on the back side of
the exiting surface high Wednesday, but confidence is rather low on
this potential.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1152 AM CST SAT DEC 21 2013
Sleet with some freezing rain mixed in has developed near MCI with
additional activity filling in upstream toward ICT. There will likely
be some breaks in this activity before it becomes more widespread
toward 21Z, but impacts are significant enough to just carry
prevailing FZRAIP through the afternoon. Increasing activity toward
21Z could lead to a thin glazing of ice and/or minor sleet
accumulations for MKC/MCI while STJ/IRK are more likely to see sleet
and some snow.
Mixed precipitation will change to all snow toward 00Z for STJ/MCI
and closer to 03Z for IRK/DMO areas. MCI-IRK corridor has the
potential to see heavy snow with visibilities approaching or
exceeding airport minimums and snowfall rates exceeding 1" per hour.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...WINTER STORM WARNING until Noon CST Sunday FOR KSZ057-060-105.
WINTER STORM WARNING until Noon CST Sunday FOR KSZ025-102>104.
MO...WINTER STORM WARNING until Noon CST Sunday FOR MOZ032-033-
037>040-043>046-053-054.
WINTER STORM WARNING until Noon CST Sunday FOR MOZ001>008-
011>017-020>025-028>031.
&&
$$
UPDATE...Hawblitzel
SHORT TERM...Bookbinder
LONG TERM...Cutter
AVIATION...Hawblitzel
AREA FORECAST DISCUSSION
NWS MEDFORD OR
857 AM PST SAT DEC 21 2013
.DISCUSSION...MOIST ONSHORE FLOW WILL PERSIST TODAY RESULTING IN
THICK CLOUD COVER OVER THE WEST SIDE. MUCH OF THE CLOUD COVER
WILL BE ALONG THE COAST AND BANKED UP AGAINST THE CASCADES AND
SISKIYOUS. THERE WILL ALSO BE SCATTERED LIGHT RAIN OR DRIZZLE,
ESPECIALLY NEAR THE MOUNTAINS AND FOOTHILLS. EXPECT A LITTLE
IMPROVEMENT THIS AFTERNOON AS THE AIR MASS BEGINS TO DRY OUT A
BIT...ESPECIALLY SOUTH OF THE UMPQUA DIVIDE. SO, WHILE NOT
CERTAIN, THERE IS THE OPPORTUNITY TO SEE A FEW SUNNY BREAKS HERE
IN MEDFORD TOWARD THE END OF THE DAY. VISIBLE IMAGERY IS SHOWING
BREAKS IN THE CLOUDS IN NORTHERN CALIFORNIA AND OVER THE EAST SIDE
THIS MORNING WITH SOME HIGH CLOUDINESS DUE TO MOUNTAIN WAVE ACTION
AND THE STRONG WINDS ALOFT. THIS SHOULD PERSIST TODAY. HIGHS WILL
BE MOSTLY IN THE 40S WITH SOME READINGS IN THE LOW 50S OVER ALONG
THE COAST AND IN NORTHERN CALIFORNIA. SPILDE
&&
.AVIATION...BASED ON THE 21/12Z TAF CYCLE.
SCATTERED LIGHT PRECIPITATION WILL CONTINUE THIS MORNING WITH THE
HIGHEST PROBABILITY OVER THE FOOTHILLS OF THE SOUTHERN OREGON
CASCADES AND THE CASCADES THEMSELVES. THIS HAS CREATED MOUNTAIN
OBSCURATIONS WITH MAINLY MVFR VSBYS AND CIGS, BUT WITH ISOLATED
IFR CONDITIONS AND ALSO AREAS OF VFR CIGS. CONDITIONS WILL BEGIN
TO IMPROVE AFTER LATE MORNING WITH CONTINUING MVFR CIGS MAINLY IN
SOUTHWEST OREGON. SVEN
&&
.PREV DISCUSSION... /ISSUED 403 AM PST SAT DEC 21 2013/
DISCUSSION...
WHILE TEMPERATURES HAVE WARMED TO ABOVE FREEZING THIS MORNING AT
MID AND UPPER ELEVATIONS AND TO THE LEE OF THE CASCADES, MOST
INTERIOR VALLEY LOCATIONS HAVE BEEN HOVERING BETWEEN 30 AND 35
DEGREES. VERY LITTLE PRECIPITATION APPEARS TO HAVE FALLEN SINCE
LAST EVENING AWAY FROM THE COAST AND UMPQUA BASIN, BUT SUSPECT
WHAT HAS ALONG WITH WHAT FELL DURING THE EVENING HAS LED TO SOME
ICY SPOTS IN THE STEEPER, MORE SHELTERED VALLEY LOCATIONS. A
SPECIAL WEATHER STATEMENT HAS BEEN ISSUED FOR PORTIONS OF THE
INTERIOR WEST SIDE AND AREAS EAST OF THE CASCADES HIGHLIGHTING
WHERE THERE MAY BE A GLAZE OF ICE THIS MORNING.
OTHERWISE, IT SHOULD BE NOTED THAT WINDS HAVE BEEN HOWLING IN THE
HIGHER MOUNTAINS TO INCLUDE THE CRATER LAKE RIM, MOUNT SHASTA, AND
PROBABLY ANYWHERE ABOVE ABOUT 6000 FEET. GUSTS IN THESE LOCATIONS
OVERNIGHT RANGED FROM AROUND 40 MPH ON THE CRATER LAKE RIM TO 99
MPH AT GREY BUTTE AT 8000 FEET ON MOUNT SHASTA. WINDS APPEAR TO
HAVE EASED A BIT BELOW 8000 FEET IN THE LAST HOUR, BUT EXPECT THEM
TO REMAIN STRONG AT HIGHER ELEVATIONS THROUGH THIS EVENING.
PRECIPITATION TODAY THROUGH THE WEEKEND WILL CONTINUE TO WANE WITH
TIME. ONSHORE FLOW TODAY WILL BE FOCUSED ON THE WEST SIDE, AND
PRECIPITATION WILL BE MOSTLY ALONG AND NEAR THE COAST AND COASTAL
MOUNTAINS, UMPQUA BASIN, AND FOOTHILLS OF THE CASCADES NORTH OF
ABOUT HIGHWAY 140. I HAVE SCALED BACK PRECIPITATION PROBABILITIES
AND AMOUNTS SOME TO BE MORE IN ACCORDANCE WITH THE 3KM HRRR MODEL,
AS IT SEEMS TO BE DEPICT WHAT HAS OCCURRED OVERNIGHT WELL.
THIS AFTERNOON THROUGH NEXT WEEKEND THE ONLY EXPECTED TRAVEL PROBLEM
WILL BE VALLEY FOG AND FREEZING FOG. A WEAK FRONTAL SYSTEM WILL
DISSIPATE AS IT ARRIVES MONDAY INTO TUESDAY, WITH ANOTHER POSSIBLY
DOING THE SAME NEXT WEEKEND. THUS, OUR COOL AND DRY DECEMBER LOOKS
AS IF IT WILL CONTINUE AS SUCH. BTL
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL
10 AM PST SUNDAY FOR PZZ350-356-370.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST SUNDAY
FOR PZZ376.
$$
MAS/BTL/SBN
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1118 AM CST SAT DEC 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CST SAT DEC 21 2013
CONCENTRATING ON REFINING THE WINTER STORM DETAILS AND IMPACTS IN
THE FORECAST SUITE. IN GENERAL...THERE HAVE BEEN MINOR CHANGES TO
THE FORECAST FOR THIS STORM...AND IT STILL LOOKS ON TRACK.
THIS SYSTEM IS WHY MANY METEOROLOGISTS WENT INTO WEATHER. THE
POWER RIGHT NOW FROM THIS SYSTEM IN THE SOUTHERN U.S. IS
REMARKABLE. GOES WATER VAPOR CLEARLY SHOWING THE STRONG TROUGH
OVER SRN NEW MEXICO WITH STRONG QVECTOR CONVERGENCE AND FORCING
OVER WESTERN TEXAS /GREAT TRANSVERSE WAVES ON IR IMAGERY/. SURFACE
PRESSURES ARE FALLING IN ARKANSAS ABOUT 1MB/HR...AND THE LOW-LEVEL
JET IS INCREASING INTO A FRONTAL ZONE DEFINED BY 34F TO 72F ACROSS
NRN AR...AND CONVECTION WITH C-G LIGHTNING. DEWPOINTS IN THE WARM
SECTOR ARE IN THE LOWER 70S ILLUSTRATING THE AMOUNT OF MOISTURE
DRAWING INTO THIS SYSTEM.
THIS STORM HAS ALL THE DYNAMICS FOR A MAJOR PRECIPITATION
PRODUCER...STRONG AND COMPACT QVECTOR CONVERGENCE/DIVERGENCE
DIPOLE...UPPER LEVEL JET ENTRANCE REGION DIVERGENCE ALOFT /JET MAX
OVER SRN CANADA OF 180KTS FORECAST/...STRONG FRONTOGENETIC FORCING
AT 600-700MB /GREAT FOR SNOW PRODUCTION/. SO...THE QUESTION IS
WHERE WILL THE SNOW BAND LAY DOWN...WITHIN A COUNTY...AND TRYING
TO UNDERSTAND WHY THE MODELS ARE STILL DIFFERENT.
SINCE 20.12Z...THE NAM HAS REALLY CHANGED ITS TUNE TO A WET AND WEST
AND MORE IN-LINE SOLUTION WITH THE GFS/EC/CANADIAN...AND HAS BEEN
CONSISTENT WITH ITS OUTCOMES IN THE LAST 3 RUNS. THE HIGHEST
PRECIPITATION BAND IS CONSISTENT WITH THE 20.12 ECMWF AND LATEST
CANADIAN/GFS RUNS...ROUGHLY FROM KDBQ-KDLL AND SOUTHEAST. THE
21.12Z ECMWF HAS SHIFTED A BIT EAST NOW. OVERALL...THE ECMWF SEEMS
TO HAVE THE BEST 500MB DEPICTION INDICATING A STRONG NEARLY CLOSED
LOW SHIFTING NORTHEAST...WHILE THE 21.00Z GFS VORTICITY IS
DISORGANIZED AND CHANNELED...AND THE GFS SURFACE LOW FURTHEST
EAST. WPC MODEL GUIDANCE DISCUSSION PREFERRED AN ECMWF SOLUTION OR
NON-NCEP ENSEMBLE. BOTTOM LINE IS THEY ARE ALL VERY REASONABLE ON
QPF/SNOW AMOUNTS EXCEPT POSSIBLY THE NAM THAT SEEMS TO SPREAD TOO
MUCH PRECIPITATION NORTHWEST...SUGGESTING IMPACTS FURTHER WEST
INTO MN/IA...A WIDE ADVISORY SNOW AREA. WHILE THIS SOLUTION CANNOT
BE DISCOUNTED...THE NORTHERN STREAM INFLUENCE/DEFORMATION SHOULD
LIMITED THE WESTWARD EXTENT....AND THE UPPER JET DIVERGENCE SEEMS
TO SUPPORT A MORE WI/IL SOLUTION FOR THE BEST LIFT /EAST/.
SNOW FORECAST REMAINS CONSISTENT...BUT HAVE MADE A SLIGHT TWEAK
WEST...MAYBE ONE-HALF A COUNTY. THE WARNING IS WELL PLACED...BUT
HAVE DECIDED TO INCLUDE JUNEAU AND ADAMS COUNTY IN CENTRAL WI.
ALSO HAVE ADDED FAYETTE COUNTY TO THE WARNING AFTER COLLABORATION
WITH DMX. HAVE CHANGED THE REMAINING WATCH COUNTIES TO AN ADVISORY
AND BASED ON THE 3 INCH SNOW TOTAL LINE...BUILT A FEW OTHER
COUNTIES INTO THE ADVISORY WESTWARD.
TIMING...
LATEST RUNS OF THE RAP INDICATE THE POSSIBILITY OF PRECIPITATION
TO THE IL/WI BORDER BY 6 PM TONIGHT. THIS IS A BIT FASTER TREND
THAN THE OTHER MODELS WHICH BEGIN SNOW AROUND 8-9PM IN THE SOUTH.
EVEN THOUGH CONSENSUS IS FOR ONSET IN THE SOUTH AT 8-9 PM HAVE
LEFT THAT START TIME 6 PM FOR NOW. THAT CAN BE ADJUSTED IF NEEDED.
HOWEVER...HAVE ADJUSTED START TIME IN CENTRAL WI TO 03Z/9PM FOR
THE WARNING...BASICALLY THE I-90 CORRIDOR. THE HEAVIEST SNOW WILL
FALL FROM ABOUT 3 AM TO 9 AM.
IMPACTS...
BECAUSE THIS STORM HAS SHORTER DURATION...WARNING SNOW
AMOUNTS WILL NOT BE UNUSUAL IN THE FORECAST AREA WITH 6 TO 8
INCHES EXPECTED AND 2 TO 5 IN THE ADVISORY. WINDS WILL BE
STRONGEST IN SERN MN INTO NERN IA...15 TO 25 MPH. THIS LEADS TO
THE UPGRADE TO WARNING IN FAYETTE AS A BIT MORE BLOWING IS
EXPECTED THERE WITH 4-5 INCHES OF SNOW.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CST SAT DEC 21 2013
SNOW SLOWLY DIMINISHES TO FLURRIES OR VERY LIGHT ACCUMULATING SNOW
SUNDAY AFTERNOON. HOWEVER...THE NORTHERN STREAM DAKOTAS SHORTWAVE
TROUGH WILL BE MOVING IN WITH THE SURGE OF ARCTIC AIR SUNDAY
NIGHT. THIS FORCING AND COLD ADVECTION WILL PROVIDE SOME
INSTABILITY AND LIFT FOR AN EXTENSION OF LIGHTLY ACCUMULATING
SNOW. SUNDAY NIGHT AND MONDAY MORNING COULD BRING ANOTHER 1-2
INCHES OF FLUFFY SNOW...WITH THE 2 INCH AMOUNTS NEAR AND NORTHEAST
OF I-94. THIS IS A LARGER CHANGE IN THE FORECAST.
AN ACTIVE PATTERN CONTINUES THROUGH THE WEEK WITH WARM ADVECTION
SNOWFALL POSSIBLE CHRISTMAS EVE AND ANOTHER VIGOROUS TROUGH
POSSIBLY THURSDAY WITH ANOTHER COLD AIR SURGE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1118 AM CST SAT DEC 21 2013
THERE LOOKS TO BE A GROWING MODEL CONSENSUS BETWEEN THE 21.12Z NAM
AND GFS...21.06Z HI-RES ARW AND NMM AND THE 21.09Z SREF MEMBERS
THAT THE WORST CONDITIONS FROM THE INCOMING WINTER STORM WILL STAY
SOUTHEAST OF BOTH TAF SITES. STILL EXPECT TO SEE SNOW OVERNIGHT
INTO SUNDAY MORNING FOR BOTH TAF SITES...BUT CONDITIONS MAY NOT BE
A BAD AS PREVIOUSLY EXPECTED. CURRENT CEILINGS ARE EXPECTED TO
SLOWLY GO DOWN THROUGH THE AFTERNOON WITH IFR AT BOTH SITES BY MID
TO LATE AFTERNOON. LOOK FOR THESE CONDITIONS TO THEN PREVAIL
THROUGH THE REST OF THE PERIOD. THE SNOW SHOULD MOVE IN LATE
TONIGHT AND IMPACT KLSE THE MOST. THE VISIBILITY WILL GO DOWN TO
IFR SHORTLY AFTER THE SNOW BEGINS AND IS EXPECTED TO GO DOWN TO
ABOUT A MILE OR SO DURING THE HEAVIEST PERIOD OF SNOW EARLY SUNDAY
MORNING. THE SREF WOULD SUGGEST THIS MAY TOO PESSIMISTIC AS IT HAS
ALMOST NO SIGNAL FOR VISIBILITIES UNDER A MILE AT KLSE AND ONLY A
SMALL SIGNAL FOR LESS THAN 3 MILE VISIBILITIES. THE SNOW WILL
START TO SHIFT OFF TO THE EAST LATE SUNDAY MORNING WITH SOME
IMPROVEMENT OCCURRING AT KRST. DID NOT SHOW ANY IMPROVEMENT AT
KLSE WITH THIS FORECAST AS THE TIMING OF THIS LOOKS TO BE RIGHT AT
THE END OF THE FORECAST PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR WIZ053.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR WIZ054-055-061.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST
SUNDAY FOR WIZ034-041-042.
WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY
FOR WIZ043-044.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR MNZ096.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR IAZ010-011-019.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR IAZ029-030.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...04