Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/16/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
826 PM MST FRI FEB 15 2013
.UPDATE...FORECAST RIGHT ON TRACK. SKIES WILL GRADUALLY CLEAR
OVERNIGHT AND OCCASIONAL GUSTY WINDS SHOULD REDEVELOP IN/NEAR
FOOTHILLS AS MOUNTAIN TOP STABLE LAYER STRENGTHENS. SUNNY AND
BREEZY CONDITIONS WILL SPREAD OVER MOST OF THE FORECAST AREA
SATURDAY WITH MUCH WARMER TEMPERATURES.
&&
.AVIATION...WINDS WERE TURNING TO SOUTHERLY WITH NORMAL
SOUTH/SOUTHWEST WINDS AT KDEN AND KAPA EXPECTED OVERNIGHT. STILL
POTENTIAL GUSTY WINDS DEVELOPING AT KBJC AFTER 08Z-10Z WITH
STRENGTHENING MOUNTAIN TOP STABLE LAYER...BUT LACK OF FLOW COULD
LIMIT POTENTIAL GUSTS TO 30 KTS. WITH SUNNY SKIES AND BETTER
MIXING ON SATURDAY...RELATIVELY HIGH CHANCE THAT GUSTY
WEST/NORTHWEST WINDS UP TO 20-25 KTS WILL SPREAD TO KDEN AND KAPA
BY 20Z-21Z SATURDAY.
&&
.PREV DISCUSSION... /ISSUED 329 PM MST FRI FEB 15 2013/
SHORT TERM...WEAK SHORTWAVE IN NORTHWEST FLOW ALOFT CLIPPING
NORTHEAST PLAINS OF COLORADO AT PRESENT TIME. RADAR INDICATING A
FEW LIGHT SHOWERS MOVING SOUTHEAST ACROSS WASHINGTON AND ELBERT
COUNTIES ON BACK EDGE OF THE MID LEVEL ASCENT. DOESN`T APPEAR MUCH
IS REACHING THE GROUND BASED ON WEB CAMS AND SURFACE OBS. ENOUGH
MIXING BEHIND SURGE HAS HELPED TO PRODUCE GUSTY WINDS ACROSS MUCH
OF PLAINS WITH SOME GUSTS NEAR 40 MPH FROM DENVER NORTH TOWARD THE
WYOMING BORDER. OVER THE MOUNTAINS...WEB CAMS STILL SHOWING LIGHT
SNOW ALONG THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES...
THOUGH HAS BEEN SHOWING SIGNS OF DECREASING DURING THE PAST
COUPLE OF HOURS. GUSTY WINDS ALSO OCCURRING ACROSS THE MOUNTAINS
AND ALONG THE FOOTHILLS. LATEST RAP SHOWS MOISTURE DEPTH
DECREASING DURING THE EVENING ACROSS THE MOUNTAINS. DESPITE
CONTINUED OROGRAPHICS...SHOULD SEE SNOW DECREASE THROUGH THE
EVENING AND COME TO AN END AROUND MIDNIGHT AS MID LEVEL WARMING
INCREASES AND LAPSE RATES DECREASE. ANY ADDITIONAL ACCUMULATIONS
WILL BE LIGHT. MID LEVEL WARMING TO DEVELOP MOUNTAIN WAVE BY
MIDNIGHT. INCREASING SUBSIDENCE WILL HELP WITH DOWNWARD MOMENTUM
TO INCREASE WINDS ACROSS MOUNTAINS AND ALONG FOOTHILLS. DOES NOT
LOOK LIKE A HIGH WIND SITUATION AS CROSS MOUNTAIN FLOW EXPECTED TO
BE AROUND 40 KTS. MODELS SHOW SOME HINTS OF THE WAVE WEAKENING
AFTER MIDNIGHT...WITH PERHAPS A DECREASE IN THE SPEEDS. ACROSS THE
PLAINS...WINDS TO GRADUALLY DECREASE DURING THE EVENING AS SURFACE
GRADIENT WEAKENS...THOUGH MAY REMAIN GUSTY NEAR THE BASE OF THE
FOOTHILLS AND FAR EASTERN PLAINS. OVERNIGHT TEMPERATURES TO BE
SLIGHTLY WARMER MOST AREAS DUE TO THE WARM AIR ADVECTION AND WIND.
HOWEVER...LOW LYING AREAS BELOW THE MID LEVEL INVERSION TO BE MUCH
COLDER WITH PERHAPS BELOW ZERO READINGS IN THE VALLEYS OF GRAND
AND JACKSON COUNTIES. ON SATURDAY...NORTHWEST FLOW ALOFT TO
CONTINUE AS UPPER RIDGE BUILDS ACROSS THE GREAT BASIN...THOUGH
GRADIENT WILL BE WEAKER. SO WINDS TO BE LIGHTER...THOUGH WILL
STILL BE A BIT GUSTY ACROSS THE MOUNTAINS AND HIGHER FOOTHILLS.
SOME MIXING POSSIBLE OVER THE PLAINS COULD CREATE SOME GUSTY
NORTHWEST WINDS DURING THE AFTERNOON. HIGHS TO WARM INTO THE 50S
ACROSS THE PLAINS.
LONG TERM...ON SATURDAY NIGHT...AN UPPER LEVEL TROUGH WILL BE OVER
THE NORTHERN ROCKIES WHILE A WEAK RIDGE MOVES ACROSS COLORADO. THIS
IS EXPECTED TO BRING DRY CONDITIONS SATURDAY NIGHT AND FOR MOST OF
SUNDAY. COULD SEE A FEW LIGHT SNOW SHOWERS LATE SUNDAY AFTERNOON
OVER THE MOUNTAINS OF NORTH CENTRAL COLORADO AS THE UPPER LEVEL
TROUGH OVER THE NORTHERN ROCKIES SHIFTS EAST-SOUTHEAST. A SURFACE
LOW WILL FORM OVER SOUTHEAST COLORADO SUNDAY IN ADVANCE OF THE
TROUGH. THIS WILL CAUSE WINDS TO TURN NORTHERLY OVER NORTHEAST
COLORADO SUNDAY AFTERNOON. EXPECT THIS TO START PULLING IN COOLER
AIR SO DROPPED HIGHS FOR SUNDAY A FEW DEGREES. HOWEVER...IT WILL
STILL BE MILD WITH HIGHS IN THE 50S.
THE BASE OF THE TROUGH WILL MOVE ACROSS WYOMING AND NORTHERN
COLORADO SUNDAY NIGHT AND EARLY MONDAY. THIS WILL LIKELY BRING A
SHOT OF LIGHT SNOW TO THE MOUNTAINS. FOR THE FRONT RANGE...NOT A
FAVORABLE SET UP BUT WINDS MAY TURN UPSLOPE FOR LONG ENOUGH TO
PRODUCE LIGHT SNOW ALONG THE FRONT RANGE. THE PLAINS MAY SEE A LIGHT
DUSTING AT BEST. SNOW MAY LINGER INTO MONDAY MORNING OVER THE
MOUNTAINS AND PALMER DIVIDE BEFORE DRIER MOVES IN FOR MONDAY
AFTERNOON.
A WEAK RIDGE WILL KEEP DRY CONDITIONS OVER COLORADO MONDAY NIGHT AND
TUESDAY. HIGHS WILL BE NEAR NORMAL TUESDAY WITH READINGS IN THE 40S.
A DEEP TROUGH WILL MOVE ONTO THE CALIFORNIA COAST TUESDAY. GENERAL
PATTERN HAS BEEN CONSISTENT FOR THE PAST FEW DAYS WITH THIS DEEP
TROUGH CLOSING OFF AND MOVING ACROSS THE GREAT BASIN AND THEN THE
ROCKIES BY MID TO LATE WEEK. DETAILS ON TRACK DEVELOPMENT STILL
NEEDS TO BE WORKED OUT. TEMPERATURES WILL BE COOL WITH MOST PLACES
SEEING PRECIPITATION SOMETIME LATE WEDNESDAY THROUGH THURSDAY. MANY
OF THE MODELS ARE SHOWING A CLOSED LOW LIFTING NORTHEAST ACROSS UTAH
ON WEDNESDAY AND THEN REFORMING THE MAIN LOW OVER SOUTHEAST COLORADO
BY THURSDAY MORNING. THIS WOULD WORK AGAINST HEAVY SNOW FOR THE
FRONT RANGE. ONCE THE LOW REFORMS OVER SOUTHEAST COLORADO...IT WILL
THEN LIFT NORTHEAST ACROSS THE CENTRAL PLAINS WHERE IT WILL LIKELY
PRODUCE BLIZZARD CONDITIONS THURSDAY AND THURSDAY NIGHT. WILL HAVE
THE HIGHEST POPS OVER THE COLORADO EASTERN PLAINS BECAUSE OF THIS.
EXPECT COOL CONDITIONS TO PREVAIL FRIDAY BECAUSE OF A LONG WAVE
TROUGH STILL OVER THE WESTERN U.S. A WEAKER TROUGH WILL BE OVER THE
GREAT BASIN FRIDAY AND WILL HAVE LOW POPS IN THE MOUNTAINS FOR THIS
SYSTEM.
AVIATION...GUSTY NORTHERLY WINDS AT DEN BEGINNING TO SHOW SOME
SIGNS OF DECREASING AND SHIFTING TO THE NORTHEAST. GRADIENT WEAKER
AND BJC AND APA. CEILINGS HAVE INCREASED TO ABOVE 7000 FEET AGL
WITH VFR PREVAILING. WINDS TO CONTINUE TO WEAKEN ACROSS THE AREA
AIRPORTS...BECOMING SOUTHEAST AROUND 03Z. SOUTHWEST DRAINAGE WINDS
TO THEN DEVELOP BY 06Z...THOUGH MAY BE MORE WESTERLY AT BJC.
POSSIBLE MOUNTAIN WAVE OVER FRONT RANGE OVERNIGHT WITH POTENTIAL
GUSTS TO 40 KTS AT BJC. WINDS TO SHIFT TO THE NORTHWEST AT 15Z
SATURDAY. SOME GUSTS TO 20 KTS POSSIBLE AT DEN. VFR TO CONTINUE
WITH UNLIMITED CEILINGS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....MEIER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
308 PM MST THU FEB 14 2013
.SHORT TERM...(TONIGHT AND TOMORROW)
ISSUED AT 308 PM MST THU FEB 14 2013
A FAST MOVING COLD FRONT HAS MOVED SOUTH OF HIGHWAY 50. THE FRONT
SHOULD CLEAR THE CO/NM BORDER BY 22Z. THE HRRR AND RAP PROG ANY
LINGERING SNOW SHOWERS TO END BY MIDNIGHT ACROSS THE AREA.
HOWEVER...THE NAM12 AND GFS ARE HOLDING ON TO SNOW SHOWERS
THROUGH 12Z ACROSS THE SOUTHERN I-25 CORRIDOR. DECIDED TO LEAVE
SOME 15 TO 35 POPS SOUTH AND WEST OF TAD IN THE GRIDS. DUE TO TO
THE FAST MOVEMENT OF THE FRONT/PRECIP...LITTLE TO NO ACCUMULATIONS
ARE EXPECTED UNDER ANY OF THE SNOW SHOWERS EAST OF THE CONTINENTAL
DIVIDE. GUSTY NORTHEAST WINDS WILL BEGIN TO RELAX AFTER 02Z. WEST
OF THE I-25 CORRIDOR...LIGHT SNOW SHOWERS WILL CONTINUE IN AND
AROUND THE LEADVILLE AREA OVERNIGHT INTO TOMORROW MORNING. THE
SAN LUIS VALLEY WILL BE MOSTLY CLEAR...COLD...AND DRY OVERNIGHT
FRIDAY...MODELS CONTINUE TO SHOW LIGHT SNOW SHOWERS IN THE LEADVILLE
AREA THROUGH FRIDAY AFTERNOON AND HAVE KEPT POPS IN PLACE AS PREVIOUSLY
FORECASTED. 700MB TEMPERATURES WILL FALLING TO -11 TO -13.5C WILL
KEEP HIGH TEMPERATURES 3-5 DEGREES COOLER ACROSS MOST LOCATIONS
FRIDAY AFTERNOON. A FEW LINGERING CLOUDS ACROSS THE AREA WILL ALSO
HELP TO CAP HIGH TEMPERATURES TOMORROW AFTERNOON. -PJC
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 308 PM MST THU FEB 14 2013
(FRIDAY NIGHT-THURSDAY)
FRIDAY NIGHT-SUNDAY...STRONG NORTH TO NORTHWEST FLOW ALOFT ACROSS
THE REGION FRIDAY NIGHT MODERATES AND BECOMES MORE WESTERLY THROUGH
THE DAY SUNDAY AS UPPER LEVEL RIDGING BUILDING ACROSS THE GREAT
BASIN FLATTENS ACROSS THE STATE AHEAD OF MORE SHORT WAVE ENERGY
MOVING ONSHORE ACROSS THE PAC NORTHWEST COAST. DRY WEATHER WITH WELL
ABOVE SEASONAL TEMPERATURES EXPECTED THROUGH THE FIRST PART OF THE
HOLIDAY WEEKEND...WITH BREEZY WEST WINDS ACROSS THE HIGHER TERRAIN
AND IMMEDIATE ADJACENT PLAINS SATURDAY AND SATURDAY NIGHT. SHOULD
SEE INCREASING HIGH CLOUDS FROM WEST TO EAST THROUGH THE DAY SUNDAY
AS THE SYSTEM CONTINUES TO MOVE ACROSS THE GREAT BASIN.
SUNDAY NIGHT-MONDAY NIGHT...STILL SOME MODEL DIFFERENCES ON AMPLITUDE
OF GREAT BASIN SYSTEM MOVING ACROSS THE ROCKIES WITH THE 12Z GFS
STILL DIGGING FURTHER SOUTH THAN THE ECMWF...HOWEVER THE GFS HAS
STARTED TO TREND FURTHER NORTH AND IS WEAKER WITH THE SYSTEM THAN
PREVIOUS RUNS. WITH THAT SAID...SHOULD STILL SEE A HEALTHY COLD
FRONT WITH A 10-20 DEGREE DROP IN TEMPERATURES FROM SUNDAY...MOST
NOTICEABLE ACROSS EASTERN COLORADO. HAVE ALSO KEPT ISOLATED TO
SCATTERED POPS INTACT ACROSS THE HIGHER TERRAIN AND IMMEDIATE
ADJACENT PLAINS...WITH NOT MUCH PRECIPITATION EXPECTED...ESPECIALLY
IF THE SYSTEM CONTINUES TO TREND FURTHER NORTH.
TUESDAY-THURSDAY...WARMER WESTERLY FLOW PROGGED ACROSS THE AREA
TUESDAY WITH INCREASING SOUTHWEST FLOW TUESDAY NIGHT AND WEDNESDAY
AHEAD OF A STRONGER SYSTEM MOVING INTO THE GREAT BASIN. SOME
DIFFERENCES IN MOVEMENT OF THIS SYSTEM WITH THE GFS LIFTING IT
ACROSS SOUTH CENTRAL COLORADO WEDNESDAY NIGHT AND INTO THE NORTHWEST
KANSAS ON THURSDAY. THE LATEST EC IS A TAD FURTHER SOUTH WITH THE
SYSTEM ACROSS SOUTHWEST KANSAS ON THURSDAY...WHICH PRODUCES BETTER
CHANCES OF SNOW AND BLOWING SNOW ACROSS THE SOUTHEAST PLAINS NORTH
OF HIGHWAY 50...ESPECIALLY AREAS ALONG THE PALMER DVD. AT ANY
RATE...MODEL CONSENSUS IS FAIRLY CONSERVATIVE THIS FAR OUT AND
HAVE INCREASED POPS TO CHANCES ALONG THE CONTDVD FOR THE WEDNESDAY
THROUGH EARLY THURSDAY PERIODS. HAVE ALSO INCREASED POPS TO SLIGHT
CHANCES ACROSS PORTIONS OF THE PLAINS. THIS SYSTEM WILL LIKELY
PRODUCE SIGNIFICANT WEATHER SOMEWHERE ACROSS THE REGION...THOUGH
TIME WILL TELL AS TO EXACTLY WHERE. -MW
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 308 PM MST THU FEB 14 2013
VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES...KALS...KCOS...AND
KPUB THROUGH TOMORROW AFTERNOON WITH AN OCCASIONAL DROP TO MVFR
CONDITIONS AT KCOS EARLY THIS EVENING DUE TO LIGHT SNOW SHOWER
ACTIVITY IN THE AREA. GUSTY WINDS FROM THE NORTH AND NORTHEAST
WILL DIMINISH LATER THIS EVENING. -PJC
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...PJC
LONG TERM...MW
AVIATION...PJC
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
939 AM MST THU FEB 14 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS STILL SEEM ON TRACK AS UPPER
TROUGH MOVES ACROSS COLORADO. LATEST MODELS CONTINUE TO SHOW
DECENT MID LEVEL QG ASCENT SPREADING ACROSS THE AREA THROUGH THE
AFTERNOON. WEB CAMS ACROSS MOUNTAINS CONTINUE TO SNOW LIGHT SNOW
ACROSS MUCH OF THE AREA...DOESN`T APPEAR TOO HEAVY AT THIS TIME.
SNOW WILL CONTINUE THROUGH THE EVENING...WITH AMOUNTS LESS THAN
ADVISORY CRITERIA. ACROSS PLAINS...FRONT CURRENTLY MOVING SOUTH
ACROSS EASTERN LARIMER AND CENTRAL WELD COUNTIES...EXTENDING INTO
SOUTHERN MORGAN AND SOUTHERN WASHINGTON COUNTIES. RADAR SHOWING
BAND OF PRECIP ALONG AND NORTH OF THE FRONT. WEB CAMS IN THIS AREA
NOT SHOWING MUCH REACHING THE GROUND ALONG THE FRONT. FRONT TO
MOVE SOUTH DURING THE MORNING...WITH PRECIP SPREADING SOUTH AND
WEST. LATEST MODELS STILL POINTING AREAS ALONG FOOTHILLS AND
WESTERN SECTIONS OF URBAN CORRIDOR FOR THE HIGHER SNOW AMOUNTS
THROUGH THE AFTERNOON AS SEVERAL BANDS APPEAR TO CONVERGE IN THIS
AREA. OVERALL...LIGHT SNOW AMOUNTS STILL ON TRACK...WITH A GENERAL
1 TO 3 INCHES IN AND NEAR FOOTHILLS...WITH LESS AMOUNTS EASTWARD.
WILL NEED TO WATCH FOR ANY BANDS PARKING IN ONE AREA FOR AN
EXTENDED PERIOD WHICH COULD INCREASE SNOW AMOUNTS...AT THIS TIME
THE CHANCES OF THIS OCCURRING IS LOW. WILL ALSO NEED TO WATCH
AN AREA FROM EASTERN MORGAN COUNTY INTO WASHINGTON COUNTY AS THE
LATEST NAM AND THE LOCAL CAIC WRF RUC SUGGESTING A BAND OF 1 TO 3
INCHES IN THIS AREA BY 00Z.
.AVIATION...CURRENT TAF TRENDS STILL SEEM ON TRACK. FRONT AND
LEADING EDGE OF PRECIP BAND JUST NORTH AND EAST OF DIA...SLOWING
SAGGING SOUTHWARD. WINDS AT DIA NOW SHOWING SIGNS OF A NORTHEAST
DIRECTION. FRONT AND PRECIP TO SPREAD ACROSS THE DENVER AREA
THROUGH THE MORNING. CEILINGS AND VISIBILITY TO LOWER BY 18Z WITH
ILS CONDITIONS A GOOD BET. MVFR CONDITIONS TO PREVAIL BETWEEN 18Z
AND 03Z WITH POSSIBLE IFR CONDITIONS. ANY SNOW ACCUMULATIONS STILL
EXPECTED TO BE LESS THAN AN INCH. CONDITIONS TO GRADUALLY IMPROVE
AFTER 03Z BUT CEILINGS SHOULD REMAIN BELOW 7000 FEET AGL.
&&
.PREV DISCUSSION... /ISSUED 330 AM MST THU FEB 14 2013/
SHORT TERM...A DISORGANIZED WEAK TROUGH WILL SLIDE FROM THE
NORTHERN ROCKIES ONTO THE PLAINS TODAY...BRINGING SOME WEAK LIFT
AND COLD ADVECTION ACROSS NORTHEASTERN COLORADO. GFS SEEMS TO HAVE
A BETTER HANDLE ON THE POSITION AND TIMING OF THE LIFT...NAM SEEMS
TOO FAR SOUTH WITH THE BEST LIFT AT THIS TIME. BEST ENHANCEMENT ON
SATELLITE UPSTREAM FROM DENVER ACTUALLY SEEMS TO HAVE VERY LITTLE
PRECIPITATION WITH IT...THE BANDED SHOWERS ARE IN THE COLDER AIR
FURTHER NORTH ACROSS WYOMING. EVEN THERE THE SHOWERS LOOK PRETTY
LIGHT. CURRENT MOTION WOULD HAVE THESE CLIPPING NORTHEASTERN
COLORADO THIS MORNING. HOWEVER...DEEPER COLD AIR WILL BE FORCED
SOUTHWARD BEHIND THE TROUGH...EVIDENCED BY PRESSURE RISES IN
MONTANA...AND THIS SHOULD HELP PULL THE SHOWER BANDS SOUTHWARD
THIS AFTERNOON. IN ADDITION THE CONVERGENCE THAT DEVELOPS IN AND
NEAR THE FOOTHILLS WILL LIKELY HELP FORCE SHOWERS SOMEWHERE IN
THAT AREA...PROBABLY WITH SOME MOTION TO THE BANDING IN THE COLD
ADVECTION. HARD TO SAY WHERE THE SYNOPTIC SCALE BANDS WILL
GO...BUT FAVORING THIS AREA OF CONVERGENCE AS THE MODELS DO MAKES
SENSE. AS A RESULT...EVEN THOUGH EXPECTED AMOUNTS WILL BE LIGHT
THE CHANCE OF GETTING A LITTLE SNOW AROUND DENVER LOOKS FAIRLY
GOOD FROM MID AFTERNOON INTO EARLY EVENING. EXPECT MOST PLACES
WILL HAVE LESS THAN AN INCH...THOUGH IF A BAND STALLS OR SOMEPLACE
GETS HIT MORE THAN ONCE HEAVIER SNOW WOULD BE POSSIBLE. WITH THE
FOOTHILLS FAVORED FOR A WHILE THE IDEA OF 1 TO 3 INCHES SEEMS
FINE.
MAIN CHANGES IN THIS PACKAGE WILL BE TO FOCUS MORE CLEARLY ON THE
AFTERNOON AND EVENING PERIODS...AND TO RAISE POPS IN THE HIGHER
MOUNTAINS AS WELL AS THERE COULD BE REPEATED PERIODS OF LIGHT
SNOW.
LONG TERM...ANOTHER BATCH OF ENERGY MOVES DOWN THE BACK SIDE OF
THE MEAN TROUGH EAST OF US ON FRIDAY. STRONG NORTHERLY FLOW ALOFT
IS PROGGED OVER THE CWA BY FRIDAY AFTERNOON INTO THE EVENING. BY
SATURDAY MORNING...THE FLOW ALOFT RELAXES AS AN UPPER RIDGE MOVES
EASTWARD. THE UPPER RIDGE MOVES ACROSS THE FORECAST AREA SATURDAY
NIGHT WITH FAIRLY WEAK ZONAL FLOW ALOFT. THE QG VERTICAL VELOCITY
FIELDS HAVE A BIT OF UPWARD MOTION PROGGED FRIDAY MORNING FOR THE
EASTERN THIRD OF THE CWA ONLY. IT`S ALL DOWNWARD MOTION FOR THE
REST OF FRIDAY THROUGH SATURDAY. VERY WEAK UPWARD MOTION IS
INDICATED FOR SATURDAY NIGHT. ON FRIDAY MORNING...THE BOUNDARY
LAYER FLOW BECOMES NORTHWESTERLY AND THAT CONTINUES INTO FRIDAY
EVENING...THEN THE FLOW IS WESTERLY THROUGH MUCH OF SATURDAY. ALL
DOWNSLOPING. FOR MOISTURE...THERE IS QUITE A BIT OVER MUCH OF THE
CWA FRIDAY...HOWEVER IS DOES GRADUALLY DECREASE THROUGH THE DAY.
MODELS HAVE IT PRETTY DRY BY 12Z SATURDAY MORNING. SATURDAY AND
SATURDAY EVENING ARE VERY DRY. THERE IS A BIT OF UPPER LEVEL
MOISTURE PROGGED TO MOVE INTO THE WESTERN HALF OF THE CWA SATURDAY
NIGHT LATE. THE QPF FIELDS HAVE A TAD OF MEASURABLE SNOWFALL OVER
THE MOUNTAINS AND EASTERN HALF OF THE PLAINS FRIDAY. AFTER THAT
THERE IS NOTHING THROUGH SUNDAY MORNING AT 12Z. WILL KEEP
"LIKELY"S GOING IN THE MOUNTAINS FOR SOME OF FRIDAY WITH THE
OROGRAPHICS AND MOISTURE IN MIND. WILL TAPER POPS OFF BY AFTERNOON
AND END THEM IN THE MOUNTAINS DURING THE EVENING. WILL LOWER POPS
TO NOTHING OR NEAR NOTHING OVER THE FOOTHILLS AND IMMEDIATE
PLAINS WITH THE STRONG DOWNSLOPE DRYING IN MIND ON FRIDAY. WILL
LEAVE SOME MINOR POPS OVER THE REST OF THE PLAINS FRIDAY. AFTER
THAT DRY FOR ALL AREAS THROUGH 12Z SUNDAY MORNING. FOR
TEMPERATURES...FRIDAY`S HIGHS WILL STAY CLOSE TO TODAY`S READINGS.
SATURDAY`S HIGHS ARE SUPPOSED TO WARM SOME 6-12 C FROM FRIDAY`S
READINGS. FOR THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...MODELS
HAVE WEAK ZONAL FLOW OVER THE CWA SUNDAY. AN UPPER TROUGH IS TO
PUSH ACROSS COLORADO SUNDAY NIGHT INTO MONDAY MORNING. PRETTY
STRONG NORTHWESTERLY FLOW ALOFT IS PROGGED MONDAY INTO MONDAY
NIGHT...THEN ANOTHER UPPER RIDGE MOVES OVER THROUGH MID DAY
TUESDAY. FOR THE REST OF TUESDAY INTO EARLY WEDNESDAY...PRETTY
STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS EXPECTED IN ADVANCE OF
THE NEXT UPPER TROUGH. THIS ONE LOOKS FAIRLY STRONG...BUT WHO
KNOWS? THE LAST SEVERAL SYSTEMS HAVE BEEN WEAK AND DISORGANIZED
AND POOR PRECIPITATION-MAKERS...YET THEY GENERALLY LOOKED MUCH
BETTER A FEW DAYS OUT. THE UPCOMING MONDAY TROUGH IS A GOOD
EXAMPLE...BUT THERE IS STILL TIME BEFORE IT ARRIVES. SO BY 00Z
LATE WEDNESDAY AFTERNOON...THE GFS SHOWS A PRETTY STRONG OPEN
TROUGH AXIS OVER THE WESTERN COLORADO BORDER. AT THE SAME
TIME...THE ECMWF HAS A CLOSED CIRCULATION AT THE BOTTOM OF ITS
UPPER TROUGH OVER THE SOUTHWESTERN CORNER OF COLORADO. THE TWO
MODELS ARE IN GOOD AGREEMENT TIMING-WISE. FOR MOISTURE...IT
INCREASES UP HIGH ON SUNDAY...AND THERE IS SOME FOR EARLY
MONDAY`S TROUGH...BUT NOTHING GREAT. YESTERDAY AND THE DAY
BEFORE`S 00Z MODEL RUNS HAD UPSLOPE AND DEEP MOISTURE FOR THE
PLAINS WITH THE EARLY MONDAY TROUGH...NOW THE ECMWF HAS LITTLE
MOISTURE AND NO UPSLOPE. THE GFS HAS BRIEF SHOT. AGAIN...THEY ARE
CHANGING FOR THE WORSE IF PRECIPITATION IS WHAT YOU SEEK.
TEMPERATURES WARM SUNDAY...THEN COOL OFF MONDAY...THEN WARM AGAIN
TUESDAY AND WEDNESDAY.
AVIATION...A COLD FRONT IS EXPECTED THROUGH DENVER IN THE 16Z TO
18Z RANGE WITH LOWERING CEILINGS AND NORTH WINDS GUSTING IN THE 20
TO 30 KNOT RANGE. EXPECT INSTRUMENT APPROACHES WILL BE NEEDED TO
KDEN BY 20Z...WITH PERIODS OF IFR CONDITIONS IN LIGHT SNOW SHOWERS
BETWEEN 21Z AND 03Z. THERE IS STILL A CHANCE OF LIGHT SHOWERS
AFTER THAT TIME...AND CEILINGS MAY REMAIN BELOW 7000 FT AGL THE
REST OF THE NIGHT...BUT WILL LIKELY BE HIGHER BY FRIDAY MORNING.
IF THERE IS SNOW ACCUMULATIONS ARE EXPECTED TO BE LESS THAN AN
INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
1009 PM EST FRI FEB 15 2013
.SYNOPSIS...
TONIGHT THROUGH SATURDAY NIGHT...WAVES OF LOW PRESSURE WILL MOVE
FROM THE MID ATLANTIC COAST TO WELL SOUTH AND EAST OF LONG ISLAND
BRINGING A LIGHT SNOWFALL FROM THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND. THE WAVES OF LOW PRESSURE WILL MERGE INTO A POWERFUL
STORM EAST OF THE GULF OF MAINE BRINGING BLUSTERY AND COLD
CONDITIONS FOR SUNDAY...BUT WITH THE BULK OF SNOWFALL OCCURRING
ACROSS COASTAL NEW ENGLAND.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 10 PM EST...PRECIPITATION IS BEGINNING TO BLOSSOM ON KENX
RADAR...PARTICULARLY ACROSS THE MID HUDSON VALLEY REGION...AND
ALSO ACROSS THE WEST/CENTRAL MOHAWK RIVER VALLEY AND AREAS JUST N
AND W OF THE IMMEDIATE CAPITAL REGION. LATEST RUC13 INDICATES AN
AREA OF ENHANCED 850-700 MB FRONTOGENETICAL FORCING ACROSS EASTERN
PA EXTENDING INTO EASTERN NYS...AND THIS AREA IS EXPECTED TO
CONTINUE EXPANDING NE OVER THE NEXT 1-3 HOURS...BEFORE GRADUALLY
SHIFTING EASTWARD A FEW HOURS AFTER MIDNIGHT. BASED ON THIS...AND
REGIONAL RADAR TRENDS...HAVE INCREASED POPS INTO THE CHC RANGE
OVER THE NEXT FEW HOURS FOR THE IMMEDIATE CAPITAL REGION AND AREAS
N AND W...INTO THE CENTRAL MOHAWK RIVER VALLEY AND THE SARATOGA
REGION. MOST OF THIS PRECIP SHOULD FALL AS SNOW...ALTHOUGH CAN NOT
RULE OUT A FEW RAINDROPS INITIALLY IN SOME LOWER ELEVATIONS GIVEN
A RELATIVELY WARM BOUNDARY LAYER. A LIGHT COATING COULD OCCUR ON
SOME COLDER SURFACES FROM THIS LIGHT SNOW.
FOR AREAS MAINLY S AND E OF ALBANY...THE PRECIPITATION AREA SHOULD
CONTINUE EXPANDING N AND E THROUGH AROUND 2 AM...BEFORE SHIFTING
SLOWLY EAST. BOUNDARY LAYER TEMPS REMAIN SOMEWHAT MILD...AND
SHOULD ALLOW FOR PRECIP TO BEGIN MAINLY AS LIGHT RAIN IN VALLEY
AREAS...WITH A RAIN/SNOW MIX ACROSS HIGHER ELEVATIONS.
HOWEVER...AFTER ABOUT 1-2 HOURS OF EVAPORATIONAL COOLING...EVEN
VALLEY AREAS SHOULD TRANSITION TO SNOW AROUND OR JUST AFTER
MIDNIGHT...WITH HIGHER ELEVATIONS CHANGING OVER MORE QUICKLY.
STILL EXPECT SNOWFALL TOTALS OF AROUND AN INCH FOR HUDSON VALLEY
LOCATIONS...WITH PERHAPS 1-3 INCHES FOR AREAS E OF THE HUDSON
RIVER INTO NW CT...AND EASTERN DUTCHESS CO. FURTHER N AND
W...STILL EXPECT MAINLY UNDER AN INCH...WITH PERHAPS 1-2 INCHES
ACROSS PORTIONS OF THE SOUTHERN BERKSHIRES.
AS FOR MIN TEMPS...GIVEN THE ABUNDANT CLOUD COVER OVERNIGHT...AND
THE FACT THAT CURRENT TEMPS ARE RUNNING A BIT WARMER THAN PREVIOUS
GUIDANCE SUGGESTED...HAVE RAISED MINS BY ABOUT 1-3 DEGREES IN MOST
AREAS...WITH MID/UPPER 20S EXPECTED WITHIN THE HUDSON RIVER VALLEY
FROM ALBANY SOUTH...AND TEENS TO LOWER/MID 20S ACROSS THE SOUTHERN
ADIRONDACKS. ELSEWHERE...EXPECT MAINLY LOWER/MID 20S.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
ANOTHER WAVE OF LOW PRESSURE MERGES OFFSHORE NEW ENGLAND AND RAPID
STRENGTHENING OF THE SYSTEM SHOULD OCCUR AS AN UPPER CUT OFF LOW
INTERACTS WITH THE SYSTEM. CONSENSUS FROM GUIDANCE AND ENSEMBLES
SUGGESTS THE STORM TRACKS TOO FAR EAST TO REALLY IMPACT OUR
FORECAST AREA...WITH PERHAPS JUST SOME ADDITIONAL LIGHT
ACCUMULATION FOR WESTERN NEW ENGLAND SATURDAY NIGHT AND EARLY
SUNDAY MORNING. STILL THERE SHOULD BE ENOUGH CLOUD COVER AND LIGHT
WINDS TO KEEP HIGH TEMPERATURES A LITTLE BELOW NORMAL...IN THE
LOWER TO MID 30S...20S IN HIGHER TERRAIN.
AS THE STORM RAPIDLY STRENGTHENS AND TRACKS INTO SOUTHEASTERN
CANADA...THE MEAN UPPER TROUGH AXIS BUILDS EAST AND VERY COLD AIR
SPILLS EAST INTO OUR REGION. THE TIGHT PRESSURE GRADIENT AROUND
THE STRONG LOW PRESSURE SHOULD SUPPORT STRONG WINDS THROUGHOUT THE
NORTHEASTERN U.S. MAKING FOR A NOTICEABLY COLD DAY SUNDAY. THERE
COULD BE WIND CHILL ISSUES AND MAYBE BORDERING ON WIND ADVISORY
WIND SPEEDS IN SOME AREAS. HIGHS SUNDAY IN THE LOWER TO MID
20S...SOME UPPER 20S SOUTHERN AREAS AND TEENS IN HIGHER TERRAIN.
THE STORM IS PREDICTED TO BE SLOW TO EXIT...AND THE WINDS MAY
DIMINISH ONLY GRADUALLY SUNDAY NIGHT INTO MONDAY. AGAIN...THERE
MAY BE SOME WIND CHILL ISSUES IN SOME AREAS...ESPECIALLY
SUNDAY NIGHT. LOWS SUNDAY NIGHT IN THE SINGLE NUMBERS TO LOWER
TEENS...AROUND OR JUST BELOW ZERO IN COLDER AREAS. HIGHS MONDAY IN
THE UPPER 20S TO LOWER 30S...LOWER 20S IN HIGHER TERRAIN.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MONDAY NIGHT...A RIDGE OF HIGH PRESSURE WILL SLIDE EASTWARD ACROSS
THE REGION...WHICH SHOULD BRING GENERALLY DRY CONDITIONS...WITH
DECREASING WIND. SOME HIGH/MID LEVEL CLOUDS MAY INCREASE LATE AT
NIGHT IN ADVANCE OF A SYSTEM APPROACHING FROM THE SOUTHWEST. EXPECT
ANOTHER COLD NIGHT...WITH MINS FALLING INTO THE SINGLE DIGITS ACROSS
NORTHERN AREAS...AND TEENS ELSEWHERE.
TUE-TUE NT...MODELS CONTINUE PREVIOUS TRENDS OF A MORE
PROGRESSIVE...AND FURTHER NORTH TRACK OF A SYSTEM DURING THIS TIME
PERIOD. STRONG WARM ADVECTION IN ADVANCE OF THIS SYSTEM SHOULD STILL
BRING A PERIOD OF PRECIPITATION TO THE REGION...MOST LIKELY TUE
AFTERNOON AND NIGHT...ALTHOUGH IT COULD START AS EARLY AS TUE
MORNING. FORECAST SOUNDINGS INDICATE MUCH OF THE REGION SHOULD BE
COLD ENOUGH TO SUPPORT MAINLY SNOW...ALTHOUGH BOUNDARY LAYER
TEMPS...AND SOME WARMING WITHIN THE 925-850 LAYER COULD ALLOW FOR
SOME RAIN TO MIX IN...ESP FOR AREAS SOUTH OF INTERSTATE 90 TUE
AFTERNOON. WILL INDICATE CHC POPS FOR THIS TIME PERIOD...WITH MAINLY
SNOW FOR NORTHERN AREAS...AND A RAIN/SNOW MIX FOR CENTRAL AND
SOUTHERN AREAS DEVELOPING BY TUE AFTERNOON...WITH PRECIPITATION
CHANGING TO SNOW ALL AREAS FOR TUE NT. MODELS HAVE TRENDED TOWARD
LESS OVERALL QPF...WITH THE 12Z/GEM REMAINING THE WETTER OUTLIER
ALLOWING FOR MORE SECONDARY COASTAL DEVELOPMENT FOR TUE NT. ASSUMING
THE 12Z/GFS/GEFS AND ECMWF PROVE CORRECT...IT APPEARS THAT THIS
EVENT SHOULD MAINLY COMPRISE OF LIGHT TO PERHAPS MODERATE
PRECIPITATION AMTS.
WED-THU NT...AS THE REMNANT UPPER LEVEL TROUGH PASSES NORTH OF THE
REGION WED AND WED EVENING...THE DEEP CYCLONIC FLOW WITHIN COLD AIR
ADVECTION SHOULD PROMOTE SCATTERED SNOW SHOWERS ACROSS MUCH OF THE
REGION...WITH THE MORE PERSISTENT SNOW SHOWERS ACROSS TRADITIONALLY
FAVORED AREAS OF THE WESTERN ADIRONDACKS...MOHAWK VALLEY...AND
POSSIBLY ACROSS THE SOUTHERN GREENS AND NORTHERN BERKSHIRES. THE
SNOW SHOWERS SHOULD DIMINISH IN AREAL COVERAGE LATE WED INTO WED
NT...FOLLOWED BY FAIR AND COLD CONDITIONS FOR THU INTO THU NT WITH
BELOW NORMAL TEMPS. SO...FOR MAX TEMPS...EXPECT LOWER/MID 30S IN
VALLEYS WED...WITH MAINLY 20S ACROSS HIGHER ELEVATIONS...WITH MAX
TEMPS A FEW DEGREES COLDER FOR THU. FOR MINS...EXPECT MAINLY 20S
ACROSS VALLEY REGIONS AND ADJACENT WESTERN NEW ENGLAND FOR WED AM
GIVEN CLOUDS AND SOME WIND...THEN TEENS IN LOWER ELEVATIONS...AND
SINGLE DIGITS ACROSS HIGHER ELEVATIONS FOR THU AM AND THU NT/FRI AM.
FRI...PREVIOUS RUNS OF VARIOUS GLOBAL DETERMINISTIC MODELS AND
ENSEMBLES HAVE INDICATED ANOTHER POTENTIAL STORM SYSTEM APPROACHING
THE REGION SOMETIME LATE FRI INTO NEXT WEEKEND. SEVERAL 12Z/15
MODELS HAVE TRENDED WEAKER...AND FURTHER SOUTH WITH ANY POTENTIAL
SYSTEM...GIVEN STRENGTHENING UPPER LEVEL RIDGING/BLOCKING ACROSS
CENTRAL/EASTERN CANADA. STILL A GREAT DEAL OF UNCERTAINTY AT THIS
TIME RANGE...SO HAVE MAINTAINED CHC POPS FOR FRI...WITH THERMAL
PROFILES SUGGESTING ALL SNOW. EXPECT MAX TEMPS TO POTENTIALLY REACH
30-35 IN LOWER ELEVATIONS...AND 20S FOR HIGHER TERRAIN.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS SOUTHERN PORTIONS OF
THE REGION LATER TONIGHT. THIS DISTURBANCE WILL BRING WIDESPREAD
MID LEVEL CLOUDS OVERNIGHT...ALONG WITH A BRIEF PERIOD OF LIGHT
SNOW AT KPOU AND KPSF AFTER MIDNIGHT...WHICH COULD INITIALLY BE
MIXED WITH RAIN. KALB APPEARS TO BE ON THE NORTHWEST EDGE OF THE
DEVELOPING PRECIPITATION SHIELD...AND WILL ONLY INDICATE VCSH FOR
NOW UNLESS RADAR TRENDS INDICATE OTHERWISE LATER THIS EVENING.
IN AREAS WHERE THE SNOW DEVELOPS...A PERIOD OF MVFR OR POSSIBLE
IFR VSBYS AND CIGS WILL BE POSSIBLE BETWEEN 06Z-10Z/SAT.
ELSEWHERE...MAINLY VFR CONDITIONS ARE EXPECTED THROUGH DAYBREAK.
ON SATURDAY...AREAS OF MVFR CIGS COULD LINGER AT KPOU AND KPSF
THROUGH AROUND 15Z. OTHERWISE...VFR CONDITIONS ARE EXPECTED.
WINDS WILL BECOME MAINLY NORTHWEST OVERNIGHT AT GENERALLY LESS
THAN 7 T. WINDS WILL BECOME NORTH TO NORTHWEST ON SATURDAY AT
GENERALLY 5-10 KT...ALTHOUGH MAY BE A BIT STRONGER AT KALB AND
KPSF...ESP FROM LATE MORNING INTO THE AFTERNOON HOURS.
OUTLOOK...
SAT NT-TUE NT...VFR. NO SIG WX.
WED...VFR BECMG MVFR/IFR. -SN/-RA POSSIBLE IN AFTERNOON.
&&
.HYDROLOGY...
NO HYDROLOGY PROBLEMS ARE EXPECTED OVER THE NEXT FEW DAYS. SNOW
MELT WILL CONTINUE TO BE GRADUAL THROUGH SATURDAY WITH ABOVE
FREEZING TEMPERATURES DURING THE DAY...AND BELOW FREEZING AT
NIGHT. TEMPERATURES WILL BECOME COLDER FOR THE 2ND HALF OF THE
WEEKEND SLOWING...AND EVEN ENDING THE SNOWMELT.
THE PREDOMINANT PTYPE TODAY INTO THE MID WEEK WILL BE SNOW. THE
SYSTEMS DURING THAT TIME FRAME ARE EXPECTED TO ONLY PRODUCE LIGHT
SNOW AMOUNTS. THEREFORE...NO IMPACTS ARE EXPECTED ON THE ALY HSA
WATERWAYS.
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...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...NAS
NEAR TERM...KL/NAS
SHORT TERM...NAS
LONG TERM...KL
AVIATION...KL
HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
706 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT MOVES ACROSS THE REGION TONIGHT AND STALLS TO OUR EAST
ON SATURDAY. A NOR`EASTER WILL DEVELOP SATURDAY NIGHT WELL
SOUTHEAST OF MONTAUK AND TRACK TOWARDS THE CANADIAN MARITIMES WITH
THE HEAVIEST PRECIPITATION REMAINING JUST EAST OF THE AREA. COLD
CANADIAN HIGH PRESSURE GRADUALLY BUILDS IN FOR SUNDAY INTO
MONDAY. A COLD FRONT TRACKS ACROSS THE REGION LATE TUESDAY
FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH THURSDAY. A COMPLEX
FRONTAL SYSTEM WILL APPROACH ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
EARLY THIS EVENING...THE COLD FRONTAL BOUNDARY IS ALONG SOUTHEAST
PA THROUGH SOUTHEAST NEW YORK WITH INCREASING CLOUDS MOVING INTO
THE LOWER HUDSON VALLEY WHILE PRECIP IS MAINLY ACROSS SOUTHEAST
PA. THE COLD FRONT WILL MOVE SLOWLY ACROSS THE REGION TONIGHT
GENERALLY BETWEEN 3Z AND 8Z WITH WINDS TURNING MORE NORTHERLY
BEHIND IT FROM WEST TO EAST. COLD AIR ADVECTION BEGINS THEREAFTER
THE STRENGTHENING NORTHERLY FLOW.
JUST SOME MINOR ADJUSTMENTS TO POPS...TEMPS...CLOUDS...AND
DEWPOINTS OVER THE NEXT FEW HOURS. OVERALL..FORECAST IS ON TRACK.
LIGHT PCPN OVER SOUTH CENTRAL PA EXPANDS RAPIDLY THIS EVENING
WITH ONSET AROUND 10 PM OVER NE NJ INTO LOWER HUDSON VALLEY.
LATEST HRRR THOUGH SUGGEST LIGHT PCPN COULD EVEN MOVE IN AN HOUR
EARLIER INTO THE LOWER HUDSON VALLEY.
WE`RE IN AN AREA OF COUPLED JET STREAKS THAT IS PROVIDING ENOUGH
OMEGA FOR THE LIGHT PCPN. QPF IS LESS THAN A QUARTER INCH AND
PERHAPS LESS THAN A TENTH. TEMPS WILL FALL INTO THE 20`S OVER THE
INTERIOR WITH 30`S ALONG THE COAST. THUS...PCPN STARTS AS LIGHT
RAIN ALONG THE COAST AND THEN MIXES WITH WET SNOW...LITTLE OR NO
ACCUMULATION. INLAND...THE PCPN IS MAINLY LIGHT SNOW...THUS 1 TO
LOCALLY 2 INCHES ARE FCST WITH THE MAIN ACCUMULATION OCCURRING ON
THE SNOW PACK DUE TO MARGINAL TEMPS AT THE START OF THE PCPN.
LIGHT PCPN AXIS SLOWLY SHIFTS EAST BY EARLY SATURDAY.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
FOCUS OF ATTENTION IS ON EXPLOSIVE CYCLOGENESIS FORCED BY THE
160+ KT SUB TROPICAL JET LEFT FRONT QUAD ON SATURDAY NIGHT. BASED
ON EXTENSIVE ANALYSIS OF ENSEMBLE SYSTEMS AND COLLABORATION WITHIN
THE NATIONAL WEATHER SERVICE INCLUDING 6 COASTAL WFO`S AND HPC
WWD...CONFIDENCE IS INCREASING ON A NEAR MISS FOR SIGNIFICANT
PCPN SATURDAY NIGHT IN OUR FCST AREA.
HAVE SEEN 12Z ECMWF...15Z SREF...12Z GEFS AND 18Z NAM.
THUS...GOING WITH A CHANCE FOR VERY LIGHT PCPN WHICH WOULD
INCLUDE SPRINKLES AND FLURRIES DURING THE DAY ON SATURDAY WITH
HIGH TEMPS CLOSE TO THE SLIGHT COOLER NAM MOS.
AS THE NOR`EASTER SPINS UP WELL OFF THE MID ATLANTIC COAST
SATURDAY EVENING...POPS INCREASE TO CATEGORICAL EAST WITH LOW
CHANCE WEST. PCPN IS ALL SNOW. HAVE AMOUNTS OF 2-3" FAR EAST AND
AROUND AN INCH FROM NEW HAVEN TO WESTERN SUFFOLK. ELSEWHERE IT`S
JUST A DUSTING. EVEN THESE AMOUNTS COULD BE HIGH.
WILL KEEP THE OUTLOOK FOR THE FAR EASTERN ZONE WITH LOW CHANCE FOR
THE TRACK TO SHIFT BACK SLIGHTLY TO THE WEST.
WINDS REALLY START TO INCREASE AFTER MIDNIGHT.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
MEDIUM RANGE MODEL GUIDANCE IS STILL IN GENERAL AGREEMENT THROUGH
THE END OF THE WEEK. TO START...INTENSE LOW PRESSURE WILL BE MOVING
UP TROUGH THE CANADIAN MARITIMES ON SUNDAY AS ITS PARENT CLOSED
UPPER LOW TRAVERSES THE REGION ON SUNDAY...WITH COLD/BLUSTERY
CONDITIONS. NW FLOW 20-30 MPH WITH GUSTS 35-45 MPH AND TEMPS ONLY
RISING TO THE UPPER 20S AND LOWER 30S WILL RESULT IN WIND CHILLS IN
THE TEENS DURING THE DAY ON SUNDAY. WINDS WILL STILL REMAIN QUITE
BRISK IN TO SUNDAY NIGHT...SO AS TEMPS FALL INTO THE TEENS AND LOWER
20S SUNDAY NIGHT...WIND CHILLS OF OF ZERO TO 10 BELOW ARE LIKELY.
TEMPS AND WIND CHILLS SHOULD RECOVER A LITTLE MON INTO MON NIGHT AS
A NARROW HIGH PRESSURE RIDGE SLIDES ACROSS...WITH HIGHS MAINLY 30-35
AND LOWS MON NIGHT IN THE 20S. AN ACCOMPANYING UPPER RIDGE SHOULD
SLIDE BY TUE MORNING...ALLOWING A FRONTAL SYSTEM TO IMPACT THE AREA
FROM THE WEST TUE INTO TUE NIGHT. IF PCPN ARRIVES EARLY ENOUGH ON
TUE...IT COULD BEGIN AS A BRIEF PD OF SNOW OR A RAIN/SNOW MIX ACROSS
THE INTERIOR...OTHERWISE RAIN SHOULD BE THE PREDOMINANT P-TYPE
DURING THE DAY. AFTER COLD FROPA TUE EVENING...PCPN COULD CHANGE
BACK TO SNOW...ESPECIALLY OVER THE INTERIOR...AS COLDER AIR BEGINS
TO FILTER BACK IN.
THE FLOW ALOFT WILL BEGIN TO TRANSITION TO A MORE BLOCKY REGIME
DURING MID TO LATE NEXT WEEK...WITH TEMPS GENERALLY NEAR AVG.
FIRST...HIGH PRESSURE WILL SLIDE ACROSS WED INTO THU EVENING...THEN
AS ONE LEG OF A DEVELOPING OMEGA OR REX BLOCK BECOMES ESTABLISHED
OVER THE NRN PLAINS LATE IN THE WEEK...A SERIES OF SRN STREAM
DISTURBANCES TRAVELING ALONG ITS SRN PERIPHERY WILL IMPACT THE AREA.
THE FIRST OF THESE SHOULD BRING A LIGHT SNOWFALL EVENT FRI INTO FRI
NIGHT...AS HIGH PRESSURE TO THE NE SUPPLIES COLD SFC AIR AND
WESTERLY FLOW ALOFT PREVENTS MID LEVEL WARMING. THE ECMWF HAS BEEN
CONSISTENTLY PREDICTING A MORE SIGNIFICANT SRN STREAM LOW BEYOND THE
END OF THE FCST PERIOD THAT WILL NEED TO BE WATCHED...SO WINTER
APPEARS FAR FROM BEING OVER.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
A COLD FRONT GRADUALLY WORKS EAST ACROSS THE REGION TONIGHT. LOW
PRESSURE DEVELOPS WELL SE OF THE REGION SAT.
LIGHT PRECIPITATION WILL OVERSPREAD WESTERN TERMINALS AFTER 03Z. THE
PRECIP WILL GRADUALLY TRANSITION TO SNOW AFTER MIDNIGHT. IFR CONDS
LIKELY AT KSWF/KHPN. ACROSS CITY TERMINALS MVFR CONDS LIKELY WITH A
PERIOD OF IFR POSSIBLE IN SN AFTER MIDNIGHT. POTENTIAL FOR AROUND AN
INCH AT KHPN AND KSWF...ELSEWHERE LITTLE OR NO SNOW ACCUMULATION ON
RUNWAYS WITH TEMPERATURES JUST ABOVE FREEZING. RA/SN GRADUALLY
SHIFTS EASTWARDS AFTER MIDNIGHT...BUT LIKELY WEAKENING AS IT DOES SO.
CONDS GRADUALLY IMPROVE TO VFR SAT MORNING...THEN GENERALLY VFR WITH
N WINDS AROUND 10 KT. MVFR OR LOWER CONDS IN LIGHT SNOW DEVELOPMENT
POSSIBLE FOR EASTERN TERMINALS AFTER 21Z...MORES KGON.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF
IMPROVEMENT TO VFR SAT MORNING.
KJFK FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF
IMPROVEMENT TO VFR SAT MORNING.
KLGA FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF
IMPROVEMENT TO VFR SAT MORNING.
KTEB FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF
IMPROVEMENT TO VFR SAT MORNING.
KHPN FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF
IMPROVEMENT TO VFR SAT MORNING.
KISP FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF
IMPROVEMENT TO VFR SAT MORNING. MVFR OR LOWER CONDS POSSIBLE IN
LIGHT SNOW AFTER 21Z.
.OUTLOOK FOR 00Z SUNDAY THROUGH TUESDAY...
.SAT NIGHT-SUN...MVFR POSSIBLE EAST OF NYC TERMINALS. OFFSHORE LOW
DEVELOPMENT WILL NEED TO WATCHED FOR ADDITIONAL PCPN. STRONG NW FLOW
WITH GUSTS OF 35 TO 40 KT POSSIBLE ON SUN.
.MON...VFR. GUSTY NW FLOW 25 TO 30 KT.
.TUE...PSBL MVFR OR LOWER WITH PCPN. GUSTY SW FLOW.
.WED...VFR. GUSTY W FLOW.
&&
.MARINE...
SUB-SCA CONDITIONS PREVAIL ON ALL WATERS INTO SATURDAY. WINDS VEER
NORTH BY LATE TONIGHT AND INCREASE ON SATURDAY.
GALES WILL LIKELY DEVELOP...ESPECIALLY EAST...LATE SAT
NIGHT AS LOW PRESSURE WELL SOUTHEAST OF MONTAUK RAPIDLY DEEPENS.
THUS GALE WATCH HAS BEEN ISSUED.
GALES LIKELY ON ALL WATERS ON SUNDAY IN THE WAKE OF INTENSE LOW
PRESSURE DEPARTING INTO THE CANADIAN MARITIMES...LASTING INTO SUNDAY
NIGHT-MON ON THE OCEAN AND THE EASTERN SOUND/BAYS.
QUIET CONDS SHOULD RETURN BY LATE DAY MON OR MON EVENING AS WEAK
HIGH PRESSURE SLIDES ACROSS. INCREASING SW FLOW AHEAD OF AN
APPROACHING FRONTAL SYSTEM COULD BRING MARGINAL SCA CONDS TO THE
OCEAN WATERS FROM LATE DAY TUE INTO TUE EVENING...CONTINUING IN W-NW
POST-FRONTAL FLOW ON WED.
&&
.HYDROLOGY...
NO HYDROLOGIC IMPACT EXPECTED WITH LIGHT PCPN THOUGH SATURDAY
NIGHT.
QPF WITH FRONTAL SYSTEMS ON TUE /MOSTLY RAIN/ AND AGAIN ON FRI
/SNOW/ SHOULD BE LIGHT AND NOT PRESENT ANY PROBLEMS.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...GALE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR
ANZ330-340-350-353.
&&
$$
SYNOPSIS...TONGUE
NEAR TERM...JM/TONGUE
SHORT TERM...TONGUE
LONG TERM...GOODMAN
AVIATION...DW
MARINE...GOODMAN/TONGUE
HYDROLOGY...TONGUE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
954 PM EST FRI FEB 15 2013
.SYNOPSIS...
LOW PRESSURE ALONG A COLD FRONT FROM SOUTHEASTERN NEW YORK STATE TO
SOUTHERN VIRGINIA WILL MOVE OFF THE COAST EARLY SATURDAY MORNING.
A NEW LOW PRESSURE SYSTEM WILL FORM ALONG THIS FRONT EAST OF NORTH
CAROLINA SATURDAY AFTERNOON...INTENSIFYING AS IT PASSES EAST OF
CAPE COD ON SUNDAY AS A LARGE AND STRONG GALE. HIGH PRESSURE IS
FORECAST TO FOLLOW FOR MONDAY INTO EARLY TUESDAY. THEN A COLD
FRONT FROM THE GREAT LAKES SHOULD MOVE THROUGH THE NORTHEAST LATER
ON TUESDAY. A LARGE HIGH PRESSURE SYSTEM FROM CENTRAL CANADA
SHOULD THEN BEGIN SLOWLY BUILD INTO THE AREA LATER ON WEDNESDAY
THROUGH THURSDAY. A WARM FRONT MAY LIFT NORTH TOWARD THE AREA
EARLY FRIDAY.
&&
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
950 PM: ISSUED SHORT FUSE WSW FOR HIGH TERRAIN NW SECTION OF OUR
FA BASED ON THE THE 00Z/16 NAM VV AND QPF...LATEST HPC QPF...AND THE
01Z/16 RAP. PRETTY GOOD CONVERGENCE ON THE SFC BOUNDARY AND SOME
FGEN IS GENERATING DECENT QPF. VSBYS IN SNOW ARE DECREASING TO A
MILE AS OF 945 PM. I KNOW THIS AREA GETS LOTS OF SNOW IN A WINTER
BUT TO GET A LITTLE BETTER VSBY FOR THE SLIPPERY TRAVEL...A SHORT
FUSE WSW WAS ISSUED.
WE ACCIDENTALLY RAN IT TIL 4AM SUNDAY BUT REWORKED THE HAZARD
PRIOR TO POSTING THE WSW. MOST OF WHAT WILL ACCUMULATE SHOULD BE
COMPLETE BY 4 AM.
RAISED POPS A BIT FOR SATURDAY IN NJ/DE WHERE THE NAM IS STARTING
TO ADD QPF AND DECENT VV. THIS SYSTEM STILL BEARS MONITORING FOR
AN ADVY SITUATION IN DE AND COASTAL NJ SATURDAY AND SATURDAY
EVENING.
850PM: IMPRESSIVE VV IN THE NEW 00Z NAM FOR THE FIRST 3-6 HRS NW
EDGE OF THE FA. SHOULD RESULT IN A BRIEF BUT MDT TO HEAVY WET SNOW
FOR 2-4 HRS FM VCNTY KRDG-KABE NWWD. WILL ADJUST FCST SLIGHTLY. WE
WILL BE ISSUING SPS`S FOR VERY SLIPPERY TRAVEL IN THIS AREA
SHORTLY.
TONIGHT...745 PM ESTF UPDATE 1.75 HRS EARLY. HAVE FURTHER DELAYED
THE CHANGE TO SNOW ABOUT AN HOUR OR TWO AND THE ONSET OF PCPN AS
WELL. THE RAP IS DOING PRETTY WELL. CLOUD TOP COOLING AND BRIGHT
BANDING IS SHOWING THE SNOW COOLING BUT THE BL IS TOO WARM AND I
DONT THINK AMOUNTS ARE GOING TO REACH FCST VALUES EXCEPT HIGH
TERRAIN AND MAINLY N OF RTE 80. RAIN MAY BE SOMEWHAT CONVECTIVE IN
NATURE. STRONG VV IN THE IDEAL DENDRITIC GROWTH ZONE MAY ASSIST
SNOW AMTS FROM THE POCONOS INTO SUSSEX COUNTY WITH A PERIOD OF MDT
SNOW THERE BETWEEN 4Z AND AND 7Z. POSSIBLY BRIEFLY DOWN TO ALLENTOWN
AROUND 05Z-06Z? ALREADY TRIMMED SNOW AMTS PRIOR TO 06Z AND EVEN
THESE ARE PROBABLY TOO LARGE BY 1/2 INCH.
TEMPS WERE WARMED FURTHER THIS EVENING I95 NWWD.
A CHANGEOVER TO SNOW SHOULD ARRIVE IN THE LEHIGH VALLEY AREA
BETWEEN 04Z-06Z AND ABOUT 07Z PHL...IF ITS STILL PRECIPITATING.
ANY SIGNIFICANT PRECIPITATION LIKELY SHUTS OFF FROM THE IMPULSE
BEFORE DAYBREAK ALTHOUGH THERE IS MODEL DISCREPANCY ON THIS.
CONFIDENCE ON SNOW AMOUNTS TONIGHT IS WELL BELOW AVERAGE. THATS
WHY I HAVENT PUBLISHED A SNOW TOTAL MAP AND JUST LETTING THE CRON
POST AMTS IN THE DAY 1 AND 2 SECTION OF OUR WINTER WX IMAGERY.
&&
.SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
THE FIRST IMPULSE SHOULD CLEAR US EARLY IN THE SHORT TERM. THEN, IF
ONE WANTS A SNOWIER FORECAST, ONE FALLS INTO THE CANADIAN/GFS
CAMP. OUR FORECAST THROUGH THE SHORT TERM LEANS AWAY FROM THIS AND
TOWARD A ECMWF/NAM KIND OF SOLUTION, ALTHOUGH WE DO INCORPORATE SOME
OF THE FORMER BECAUSE OF THE UNCERTAINTY. THE GFS AND CANADIAN ARE
DEVELOPING MORE OF A NEGATIVE TILT WITH A STRONGER SECOND IMPULSE AT
H5, AND THAT HAS THEM DEEPER AND FURTHER EAST WITH THE ASSOCIATED
LOW PRESSURE SYSTEM (THE MAIN ONE WITH THIS MAJOR TROUGH AXIS).
ALTHOUGH OUR QPF IS ON THE LIGHTER SIDE BECAUSE WE FAVOR A LESS
VIGOROUS SOLUTION AT OUR LATITUDE, ALL MODEL SOUNDINGS SAY THAT ALL
AREAS WOULD SEE SNOW EITHER FROM THE START OF OR ONLY A FEW HOURS
INTO THE SHORT TERM. WE HAVE THEREFORE ADJUSTED MAX TEMPERATURES
DOWNWARD.
OUR QPF AND SNOW VALUES IN THE LATTER PART OF THE SHORT TERM AND THE
FIRST PART OF THE LONG TERM COMBINED WOULD BRING OUR EASTERN ZONES
INTO ADVISORY TERRITORY. GIVEN THE UNCERTAINTY, WE HAVE DECIDED NOT
TO ISSUE ONE AT THIS TIME.
WE DO NOTE THAT IF OUR FORECAST WERE CORRECT FROM THE NEAR TERM
THROUGH THE EARLY PART OF THE LONG TERM, THEN WE WOULD SEE LOWER END
ADVISORY SNOW AMOUNTS OVER A FAIR AMOUNT OF THE FORECAST AREA.
HOWEVER, THIS WOULD HAPPEN OVER A PERIOD OF AT LEAST 24 HOURS, SOME
OF WHICH WOULD BE FREE OF SIGNIFICANT PRECIPITATION.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MODELS CONTINUE TO DIFFER ON HOW MUCH SNOW MIGHT FALL LATER SATURDAY
AND SATURDAY NIGHT. THE LATEST RUN OF THE GFS INDICATES A SLIGHTLY
MORE WESTERN TRACK WHILE THE LATEST ECMWF INDICATES A MORE
EASTERLY TRACK. AS A RESULT...NO DRASTIC CHANGE HAS BEEN MADE TO THE
FORECAST AT THIS POINT IN TIME. BASICALLY AN ADVISORY TO
SUB-ADVISORY EVENT FOR THE CWA, WITH THE HIGHEST AMOUNTS CLOSEST TO
THE COASTAL AREAS...WITH LESSER AMOUNTS FURTHER INLAND. WHATEVER
SNOW DOES FALL, THE BULK OF IT SHOULD BE OVER BY 6 AM SUNDAY. SLIGHT
POPS WERE ADDED TO THE WEATHER GRIDS FOR SUNDAY DUE TO THE PROXIMITY
OF THE MID-LEVEL TROUGH, BUT NOTHING SIGNIFICANT IS EXPECTED DURING
THIS TIME PERIOD. A BLUSTERY DAY IS EXPECTED IN THE CWA ON SUNDAY
DUE TO THE PRESSURE GRADIENT FROM THE EXITING STORM. WITH HIGH
TEMPERATURES IN THE MID 20S IN THE NORTH AND LOW TO MID 30S
SOUTH...IT WILL FEEL LIKE WINTER AGAIN. WHETHER OR NOT WIND
ADVISORIES WILL BE NECESSARY WILL DEPEND ON HOW FAR EAST THE STORM
TRACK HAPPENS TO BE.
MONDAY SHOULD BE A LESS WINDIER DAY WITH SUNNY SKIES. TEMPERATURES
THOUGH SHOULD STILL BE ABOUT 5 TO 10 DEGREES COLDER THAN AVERAGE.
AS THE HIGH SLIDES OFF THE COAST EARLY TUESDAY...A WARM FRONT WILL
LIFT NORTH ALLOWING TEMPERATURES TO RISE INTO THE MID TO UPPER 40S
IN MOST PLACES. PRECIPITATION COULD START OUT AS SNOW...BUT SHOULD
CHANGE OVER TO RAIN AS THE DAY WEAR ON. A COLD FRONT ASSOCIATED WITH
A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES REGION WILL
PASS THROUGH THE CWA TUESDAY EVENING/NIGHT...WHICH WILL BRING BACK
COLDER TEMPERATURES AND CHANGE ANY LINGERING RAIN TO
SNOW...ESPECIALLY IN THE NORTH. THEN BASICALLY BENIGN WEATHER UNTIL
THE NEXT SYSTEM APPROACHES FROM THE WEST ON FRIDAY. PRECIP WITH THAT
EVENT LOOKS LIKE IT WILL BE MAINLY RAIN IN THE SOUTH WITH A LEAST A
MIXTURE IN THE NORTH.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...CONDITIONS ARE FORECAST TO DETERIORATE TO MVFR OR IFR
OVER ALL THE TAF SITES FROM NORTHWEST TO SOUTHEAST. THERE MAY BE A
PERIOD WHEN THEY IMPROVE TO MVFR OR VFR ON SATURDAY MORNING BEFORE
THEY MAY BEGIN TO DETERIORATE LATER IN THE DAY.
WINDS SHOULD VEER FROM SOUTHWEST OR WEST TO NORTH DURING THE COURSE
OF THE TAF PERIOD WITH SOME GUSTINESS TO AROUND 20 KT EARLY IN THE
PERIOD AND PERHAPS AGAIN LATE.
OUTLOOK...
SATURDAY NIGHT...IFR CONDITIONS...ESPECIALLY SOUTH AND EAST OF
I-95...IMPROVING TO VFR TOWARD MORNING.
SUNDAY...MAINLY VFR AND BLUSTERY. POSSIBLE MVFR SNOW SHWRS NORTH.
NORTHWEST WINDS GUSTING 25 TO 30 KNOTS. CONFIDENCE MODERATE.
MONDAY AND MONDAY NIGHT...MAINLY VFR. CONFIDENCE HIGH.
TUESDAY...LOWERING TO MVFR OR IFR IN MIXED PRECIPITATION IN THE
MORNING. CHANCE OF LLWS. CONFIDENCE IS MODERATE.
TUESDAY NIGHT...IMPROVING TO VFR.
WEDNESDAY...MAINLY VFR.
&&
.MARINE...
SUB-ADVISORY CONDITIONS ARE FORECAST INTO SATURDAY, BUT THEN WILL
APPROACH OR REACH ADVISORY CONDITIONS LATE IN THE DAY ON GOOD COLD
AIR ADVECTION AND A NORTHWEST FLOW. SEAS SHOULD BUILD TO ADVISORY
CONDITIONS BY LATE SATURDAY AFTERNOON.
OUTLOOK...
THE DEVELOPING AND DEEPENING OFFSHORE LOW OFF NORTH CAROLINA WILL
CONTINUE SCA CONDITIONS OVER MARINE AREA (OCEAN AND DELAWARE BAY)
WIDESPREAD SCA CONDITIONS THROUGH THE REMAIN PORTION OF THE WEEKEND.
DEPENDING ON THE PATH OF THIS STORM...GALES ARE EVEN POSSIBLE
SATURDAY NIGHT INTO SUNDAY ON THE OCEAN AND LOWER DELAWARE BAY.
THIS SITUATION WILL BE RE- EXAMINED WITH LATER MODEL RUNS. A
SOUTHWEST FLOW BEHIND AN ADVANCING WARM FRONT IS EXPECTED TO SCA
BACK TO THE FORECAST WATERS ON TUESDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 5 AM EST SATURDAY FOR PAZ055.
NJ...WINTER WEATHER ADVISORY UNTIL 5 AM EST SATURDAY FOR NJZ001-007-
008.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DRAG/MIKETTA
NEAR TERM...DRAG 954P
SHORT TERM...DELISI
LONG TERM...MIKETTA
AVIATION...DELISI/DRAG/MIKETTA
MARINE...DELISI/DRAG/MIKETTA
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
850 PM EST FRI FEB 15 2013
.SYNOPSIS...
LOW PRESSURE ALONG A COLD FRONT FROM SOUTHEASTERN NEW YORK STATE TO
SOUTHERN VIRGINIA WILL MOVE OFF THE COAST EARLY SATURDAY MORNING.
A NEW LOW PRESSURE SYSTEM WILL FORM ALONG THIS FRONT EAST OF NORTH
CAROLINA SATURDAY AFTERNOON...INTENSIFYING AS IT PASSES EAST OF
CAPE COD ON SUNDAY AS A LARGE AND STRONG GALE. HIGH PRESSURE IS
FORECAST TO FOLLOW FOR MONDAY INTO EARLY TUESDAY. THEN A COLD
FRONT FROM THE GREAT LAKES SHOULD MOVE THROUGH THE NORTHEAST LATER
ON TUESDAY. A LARGE HIGH PRESSURE SYSTEM FROM CENTRAL CANADA
SHOULD THEN BEGIN SLOWLY BUILD INTO THE AREA LATER ON WEDNESDAY
THROUGH THURSDAY. A WARM FRONT MAY LIFT NORTH TOWARD THE AREA
EARLY FRIDAY.
&&
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
850PM: IMPRESSIVE VV IN THE NEW 00Z NAM FOR THE FIRST 3-6 HRS NW
EDGE OF THE FA. SHOULD RESULT IN A BRIEF BUT MDT TO HEAVY WET SNOW
FOR 2-4 HRS FM VCNTY KRDG-KABE NWWD. WILL ADJUST FCST SLIGHTLY. WE
WILL BE ISSUING SPS`S FOR VERY SLIPPERY TRAVEL IN THIS AREA SHORTLY.
TONIGHT...745 PM ESTF UPDATE 1.75 HRS EARLY. HAVE FURTHER DELAYED
THE CHANGE TO SNOW ABOUT AN HOUR OR TWO AND THE ONSET OF PCPN AS
WELL. THE RAP IS DOING PRETTY WELL. CLOUD TOP COOLING AND BRIGHT
BANDING IS SHOWING THE SNOW COOLING BUT THE BL IS TOO WARM AND I
DONT THINK AMOUNTS ARE GOING TO REACH FCST VALUES EXCEPT HIGH
TERRAIN AND MAINLY N OF RTE 80. RAIN MAY BE SOMEWHAT CONVECTIVE IN
NATURE. STRONG VV IN THE IDEAL DENDRITIC GROWTH ZONE MAY ASSIST
SNOW AMTS FROM THE POCONOS INTO SUSSEX COUNTY WITH A PERIOD OF MDT
SNOW THERE BETWEEN 4Z AND AND 7Z. POSSIBLY BRIEFLY DOWN TO ALLENTOWN
AROUND 05Z-06Z? ALREADY TRIMMED SNOW AMTS PRIOR TO 06Z AND EVEN
THESE ARE PROBABLY TOO LARGE BY 1/2 INCH.
TEMPS WERE WARMED FURTHER THIS EVENING I95 NWWD.
A CHANGEOVER TO SNOW SHOULD ARRIVE IN THE LEHIGH VALLEY AREA
BETWEEN 04Z-06Z AND ABOUT 07Z PHL...IF ITS STILL PRECIPITATING.
ANY SIGNIFICANT PRECIPITATION LIKELY SHUTS OFF FROM THE IMPULSE
BEFORE DAYBREAK ALTHOUGH THERE IS MODEL DISCREPANCY ON THIS.
CONFIDENCE ON SNOW AMOUNTS TONIGHT IS WELL BELOW AVERAGE. THATS
WHY I HAVENT PUBLISHED A SNOW TOTAL MAP AND JUST LETTING THE CRON
POST AMTS IN THE DAY 1 AND 2 SECTION OF OUR WINTER WX IMAGERY.
&&
.SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
THE FIRST IMPULSE SHOULD CLEAR US EARLY IN THE SHORT TERM. THEN, IF
ONE WANTS A SNOWIER FORECAST, ONE FALLS INTO THE CANADIAN/GFS
CAMP. OUR FORECAST THROUGH THE SHORT TERM LEANS AWAY FROM THIS AND
TOWARD A ECMWF/NAM KIND OF SOLUTION, ALTHOUGH WE DO INCORPORATE SOME
OF THE FORMER BECAUSE OF THE UNCERTAINTY. THE GFS AND CANADIAN ARE
DEVELOPING MORE OF A NEGATIVE TILT WITH A STRONGER SECOND IMPULSE AT
H5, AND THAT HAS THEM DEEPER AND FURTHER EAST WITH THE ASSOCIATED
LOW PRESSURE SYSTEM (THE MAIN ONE WITH THIS MAJOR TROUGH AXIS).
ALTHOUGH OUR QPF IS ON THE LIGHTER SIDE BECAUSE WE FAVOR A LESS
VIGOROUS SOLUTION AT OUR LATITUDE, ALL MODEL SOUNDINGS SAY THAT ALL
AREAS WOULD SEE SNOW EITHER FROM THE START OF OR ONLY A FEW HOURS
INTO THE SHORT TERM. WE HAVE THEREFORE ADJUSTED MAX TEMPERATURES
DOWNWARD.
OUR QPF AND SNOW VALUES IN THE LATTER PART OF THE SHORT TERM AND THE
FIRST PART OF THE LONG TERM COMBINED WOULD BRING OUR EASTERN ZONES
INTO ADVISORY TERRITORY. GIVEN THE UNCERTAINTY, WE HAVE DECIDED NOT
TO ISSUE ONE AT THIS TIME.
WE DO NOTE THAT IF OUR FORECAST WERE CORRECT FROM THE NEAR TERM
THROUGH THE EARLY PART OF THE LONG TERM, THEN WE WOULD SEE LOWER END
ADVISORY SNOW AMOUNTS OVER A FAIR AMOUNT OF THE FORECAST AREA.
HOWEVER, THIS WOULD HAPPEN OVER A PERIOD OF AT LEAST 24 HOURS, SOME
OF WHICH WOULD BE FREE OF SIGNIFICANT PRECIPITATION.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MODELS CONTINUE TO DIFFER ON HOW MUCH SNOW MIGHT FALL LATER SATURDAY
AND SATURDAY NIGHT. THE LATEST RUN OF THE GFS INDICATES A SLIGHTLY
MORE WESTERN TRACK WHILE THE LATEST ECMWF INDICATES A MORE
EASTERLY TRACK. AS A RESULT...NO DRASTIC CHANGE HAS BEEN MADE TO THE
FORECAST AT THIS POINT IN TIME. BASICALLY AN ADVISORY TO
SUB-ADVISORY EVENT FOR THE CWA, WITH THE HIGHEST AMOUNTS CLOSEST TO
THE COASTAL AREAS...WITH LESSER AMOUNTS FURTHER INLAND. WHATEVER
SNOW DOES FALL, THE BULK OF IT SHOULD BE OVER BY 6 AM SUNDAY. SLIGHT
POPS WERE ADDED TO THE WEATHER GRIDS FOR SUNDAY DUE TO THE PROXIMITY
OF THE MID-LEVEL TROUGH, BUT NOTHING SIGNIFICANT IS EXPECTED DURING
THIS TIME PERIOD. A BLUSTERY DAY IS EXPECTED IN THE CWA ON SUNDAY
DUE TO THE PRESSURE GRADIENT FROM THE EXITING STORM. WITH HIGH
TEMPERATURES IN THE MID 20S IN THE NORTH AND LOW TO MID 30S
SOUTH...IT WILL FEEL LIKE WINTER AGAIN. WHETHER OR NOT WIND
ADVISORIES WILL BE NECESSARY WILL DEPEND ON HOW FAR EAST THE STORM
TRACK HAPPENS TO BE.
MONDAY SHOULD BE A LESS WINDIER DAY WITH SUNNY SKIES. TEMPERATURES
THOUGH SHOULD STILL BE ABOUT 5 TO 10 DEGREES COLDER THAN AVERAGE.
AS THE HIGH SLIDES OFF THE COAST EARLY TUESDAY...A WARM FRONT WILL
LIFT NORTH ALLOWING TEMPERATURES TO RISE INTO THE MID TO UPPER 40S
IN MOST PLACES. PRECIPITATION COULD START OUT AS SNOW...BUT SHOULD
CHANGE OVER TO RAIN AS THE DAY WEAR ON. A COLD FRONT ASSOCIATED WITH
A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES REGION WILL
PASS THROUGH THE CWA TUESDAY EVENING/NIGHT...WHICH WILL BRING BACK
COLDER TEMPERATURES AND CHANGE ANY LINGERING RAIN TO
SNOW...ESPECIALLY IN THE NORTH. THEN BASICALLY BENIGN WEATHER UNTIL
THE NEXT SYSTEM APPROACHES FROM THE WEST ON FRIDAY. PRECIP WITH THAT
EVENT LOOKS LIKE IT WILL BE MAINLY RAIN IN THE SOUTH WITH A LEAST A
MIXTURE IN THE NORTH.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...CONDITIONS ARE FORECAST TO DETERIORATE TO MVFR OR IFR
OVER ALL THE TAF SITES FROM NORTHWEST TO SOUTHEAST. THERE MAY BE A
PERIOD WHEN THEY IMPROVE TO MVFR OR VFR ON SATURDAY MORNING BEFORE
THEY MAY BEGIN TO DETERIORATE LATER IN THE DAY.
WINDS SHOULD VEER FROM SOUTHWEST OR WEST TO NORTH DURING THE COURSE
OF THE TAF PERIOD WITH SOME GUSTINESS TO AROUND 20 KT EARLY IN THE
PERIOD AND PERHAPS AGAIN LATE.
OUTLOOK...
SATURDAY NIGHT...IFR CONDITIONS...ESPECIALLY SOUTH AND EAST OF
I-95...IMPROVING TO VFR TOWARD MORNING.
SUNDAY...MAINLY VFR AND BLUSTERY. POSSIBLE MVFR SNOW SHWRS NORTH.
NORTHWEST WINDS GUSTING 25 TO 30 KNOTS. CONFIDENCE MODERATE.
MONDAY AND MONDAY NIGHT...MAINLY VFR. CONFIDENCE HIGH.
TUESDAY...LOWERING TO MVFR OR IFR IN MIXED PRECIPITATION IN THE
MORNING. CHANCE OF LLWS. CONFIDENCE IS MODERATE.
TUESDAY NIGHT...IMPROVING TO VFR.
WEDNESDAY...MAINLY VFR.
&&
.MARINE...
SUB-ADVISORY CONDITIONS ARE FORECAST INTO SATURDAY, BUT THEN WILL
APPROACH OR REACH ADVISORY CONDITIONS LATE IN THE DAY ON GOOD COLD
AIR ADVECTION AND A NORTHWEST FLOW. SEAS SHOULD BUILD TO ADVISORY
CONDITIONS BY LATE SATURDAY AFTERNOON.
OUTLOOK...
THE DEVELOPING AND DEEPENING OFFSHORE LOW OFF NORTH CAROLINA WILL
CONTINUE SCA CONDITIONS OVER MARINE AREA (OCEAN AND DELAWARE BAY)
WIDESPREAD SCA CONDITIONS THROUGH THE REMAIN PORTION OF THE WEEKEND.
DEPENDING ON THE PATH OF THIS STORM...GALES ARE EVEN POSSIBLE
SATURDAY NIGHT INTO SUNDAY ON THE OCEAN AND LOWER DELAWARE BAY.
THIS SITUATION WILL BE RE- EXAMINED WITH LATER MODEL RUNS. A
SOUTHWEST FLOW BEHIND AN ADVANCING WARM FRONT IS EXPECTED TO SCA
BACK TO THE FORECAST WATERS ON TUESDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DRAG/MIKETTA
NEAR TERM...DRAG 850P
SHORT TERM...DELISI
LONG TERM...MIKETTA
AVIATION...DELISI/DRAG/MIKETTA
MARINE...DELISI/DRAG/MIKETTA
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
819 PM EST FRI FEB 15 2013
.SYNOPSIS...
LOW PRESSURE ALONG A COLD FRONT FROM SOUTHEASTERN NEW YORK STATE TO
SOUTHERN VIRGINIA WILL MOVE OFF THE COAST EARLY SATURDAY MORNING.
A NEW LOW PRESSURE SYSTEM WILL FORM ALONG THIS FRONT EAST OF NORTH
CAROLINA SATURDAY AFTERNOON...INTENSIFYING AS IT PASSES EAST OF
CAPE COD ON SUNDAY AS A LARGE AND STRONG GALE. HIGH PRESSURE IS
FORECAST TO FOLLOW FOR MONDAY INTO EARLY TUESDAY. THEN A COLD
FRONT FROM THE GREAT LAKES SHOULD MOVE THROUGH THE NORTHEAST LATER
ON TUESDAY. A LARGE HIGH PRESSURE SYSTEM FROM CENTRAL CANADA
SHOULD THEN BEGIN SLOWLY BUILD INTO THE AREA LATER ON WEDNESDAY
THROUGH THURSDAY. A WARM FRONT MAY LIFT NORTH TOWARD THE AREA
EARLY FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
TONIGHT...745 PM ESTF UPDATE 1.75 HRS EARLY. HAVE FURTHER DELAYED
THE CHANGE TO SNOW ABOUT AN HOUR OR TWO AND THE ONSET OF PCPN AS
WELL. THE RAP IS DOING PRETTY WELL. CLOUD TOP COOLING AND BRIGHT
BANDING IS SHOWING THE SNOW COOLING BUT THE BL IS TOO WARM AND I
DONT THINK AMOUNTS ARE GOING TO REACH FCST VALUES EXCEPT HIGH
TERRAIN AND MAINLY N OF RTE 80. RAIN MAY BE SOMEWHAT CONVECTIVE IN
NATURE. STRONG VV IN THE IDEAL DENDRITIC GROWTH ZONE MAY ASSIST
SNOW AMTS FROM THE POCONOS INTO SUSSEX COUNTY WITH A PERIOD OF MDT
SNOW THERE BETWEEN 4Z AND AND 7Z. POSSIBLY BRIEFLY DOWN TO ALLENTOWN
AROUND 05Z-06Z? ALREADY TRIMMED SNOW AMTS PRIOR TO 06Z AND EVEN
THESE ARE PROBABLY TOO LARGE BY 1/2 INCH.
TEMPS WERE WARMED FURTHER THIS EVENING I95 NWWD.
A CHANGEOVER TO SNOW SHOULD ARRIVE IN THE LEHIGH VALLEY AREA
BETWEEN 04Z-06Z AND ABOUT 07Z PHL...IF ITS STILL PRECIPITATING.
ANY SIGNIFICANT PRECIPITATION LIKELY SHUTS OFF FROM THE IMPULSE
BEFORE DAYBREAK ALTHOUGH THERE IS MODEL DISCREPANCY ON THIS.
CONFIDENCE ON SNOW AMOUNTS TONIGHT IS WELL BELOW AVERAGE. THATS
WHY I HAVENT PUBLISHED A SNOW TOTAL MAP AND JUST LETTING THE CRON
POST AMTS IN THE DAY 1 AND 2 SECTION OF OUR WINTER WX IMAGERY.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
THE FIRST IMPULSE SHOULD CLEAR US EARLY IN THE SHORT TERM. THEN, IF
ONE WANTS A SNOWIER FORECAST, ONE FALLS INTO THE CANADIAN/GFS
CAMP. OUR FORECAST THROUGH THE SHORT TERM LEANS AWAY FROM THIS AND
TOWARD A ECMWF/NAM KIND OF SOLUTION, ALTHOUGH WE DO INCORPORATE SOME
OF THE FORMER BECAUSE OF THE UNCERTAINTY. THE GFS AND CANADIAN ARE
DEVELOPING MORE OF A NEGATIVE TILT WITH A STRONGER SECOND IMPULSE AT
H5, AND THAT HAS THEM DEEPER AND FURTHER EAST WITH THE ASSOCIATED
LOW PRESSURE SYSTEM (THE MAIN ONE WITH THIS MAJOR TROUGH AXIS).
ALTHOUGH OUR QPF IS ON THE LIGHTER SIDE BECAUSE WE FAVOR A LESS
VIGOROUS SOLUTION AT OUR LATITUDE, ALL MODEL SOUNDINGS SAY THAT ALL
AREAS WOULD SEE SNOW EITHER FROM THE START OF OR ONLY A FEW HOURS
INTO THE SHORT TERM. WE HAVE THEREFORE ADJUSTED MAX TEMPERATURES
DOWNWARD.
OUR QPF AND SNOW VALUES IN THE LATTER PART OF THE SHORT TERM AND THE
FIRST PART OF THE LONG TERM COMBINED WOULD BRING OUR EASTERN ZONES
INTO ADVISORY TERRITORY. GIVEN THE UNCERTAINTY, WE HAVE DECIDED NOT
TO ISSUE ONE AT THIS TIME.
WE DO NOTE THAT IF OUR FORECAST WERE CORRECT FROM THE NEAR TERM
THROUGH THE EARLY PART OF THE LONG TERM, THEN WE WOULD SEE LOWER END
ADVISORY SNOW AMOUNTS OVER A FAIR AMOUNT OF THE FORECAST AREA.
HOWEVER, THIS WOULD HAPPEN OVER A PERIOD OF AT LEAST 24 HOURS, SOME
OF WHICH WOULD BE FREE OF SIGNIFICANT PRECIPITATION.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MODELS CONTINUE TO DIFFER ON HOW MUCH SNOW MIGHT FALL LATER SATURDAY
AND SATURDAY NIGHT. THE LATEST RUN OF THE GFS INDICATES A SLIGHTLY
MORE WESTERN TRACK WHILE THE LATEST ECMWF INDICATES A MORE
EASTERLY TRACK. AS A RESULT...NO DRASTIC CHANGE HAS BEEN MADE TO THE
FORECAST AT THIS POINT IN TIME. BASICALLY AN ADVISORY TO
SUB-ADVISORY EVENT FOR THE CWA, WITH THE HIGHEST AMOUNTS CLOSEST TO
THE COASTAL AREAS...WITH LESSER AMOUNTS FURTHER INLAND. WHATEVER
SNOW DOES FALL, THE BULK OF IT SHOULD BE OVER BY 6 AM SUNDAY. SLIGHT
POPS WERE ADDED TO THE WEATHER GRIDS FOR SUNDAY DUE TO THE PROXIMITY
OF THE MID-LEVEL TROUGH, BUT NOTHING SIGNIFICANT IS EXPECTED DURING
THIS TIME PERIOD. A BLUSTERY DAY IS EXPECTED IN THE CWA ON SUNDAY
DUE TO THE PRESSURE GRADIENT FROM THE EXITING STORM. WITH HIGH
TEMPERATURES IN THE MID 20S IN THE NORTH AND LOW TO MID 30S
SOUTH...IT WILL FEEL LIKE WINTER AGAIN. WHETHER OR NOT WIND
ADVISORIES WILL BE NECESSARY WILL DEPEND ON HOW FAR EAST THE STORM
TRACK HAPPENS TO BE.
MONDAY SHOULD BE A LESS WINDIER DAY WITH SUNNY SKIES. TEMPERATURES
THOUGH SHOULD STILL BE ABOUT 5 TO 10 DEGREES COLDER THAN AVERAGE.
AS THE HIGH SLIDES OFF THE COAST EARLY TUESDAY...A WARM FRONT WILL
LIFT NORTH ALLOWING TEMPERATURES TO RISE INTO THE MID TO UPPER 40S
IN MOST PLACES. PRECIPITATION COULD START OUT AS SNOW...BUT SHOULD
CHANGE OVER TO RAIN AS THE DAY WEAR ON. A COLD FRONT ASSOCIATED WITH
A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES REGION WILL
PASS THROUGH THE CWA TUESDAY EVENING/NIGHT...WHICH WILL BRING BACK
COLDER TEMPERATURES AND CHANGE ANY LINGERING RAIN TO
SNOW...ESPECIALLY IN THE NORTH. THEN BASICALLY BENIGN WEATHER UNTIL
THE NEXT SYSTEM APPROACHES FROM THE WEST ON FRIDAY. PRECIP WITH THAT
EVENT LOOKS LIKE IT WILL BE MAINLY RAIN IN THE SOUTH WITH A LEAST A
MIXTURE IN THE NORTH.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...CONDITIONS ARE FORECAST TO DETERIORATE TO MVFR OR IFR
OVER ALL THE TAF SITES FROM NORTHWEST TO SOUTHEAST. THERE MAY BE A
PERIOD WHEN THEY IMPROVE TO MVFR OR VFR ON SATURDAY MORNING BEFORE
THEY MAY BEGIN TO DETERIORATE LATER IN THE DAY.
WINDS SHOULD VEER FROM SOUTHWEST OR WEST TO NORTH DURING THE COURSE
OF THE TAF PERIOD WITH SOME GUSTINESS TO AROUND 20 KT EARLY IN THE
PERIOD AND PERHAPS AGAIN LATE.
OUTLOOK...
SATURDAY NIGHT...IFR CONDITIONS...ESPECIALLY SOUTH AND EAST OF
I-95...IMPROVING TO VFR TOWARD MORNING.
SUNDAY...MAINLY VFR AND BLUSTERY. POSSIBLE MVFR SNOW SHWRS NORTH.
NORTHWEST WINDS GUSTING 25 TO 30 KNOTS. CONFIDENCE MODERATE.
MONDAY AND MONDAY NIGHT...MAINLY VFR. CONFIDENCE HIGH.
TUESDAY...LOWERING TO MVFR OR IFR IN MIXED PRECIPITATION IN THE
MORNING. CHANCE OF LLWS. CONFIDENCE IS MODERATE.
TUESDAY NIGHT...IMPROVING TO VFR.
WEDNESDAY...MAINLY VFR.
&&
.MARINE...
SUB-ADVISORY CONDITIONS ARE FORECAST INTO SATURDAY, BUT THEN WILL
APPROACH OR REACH ADVISORY CONDITIONS LATE IN THE DAY ON GOOD COLD
AIR ADVECTION AND A NORTHWEST FLOW. SEAS SHOULD BUILD TO ADVISORY
CONDITIONS BY LATE SATURDAY AFTERNOON.
OUTLOOK...
THE DEVELOPING AND DEEPENING OFFSHORE LOW OFF NORTH CAROLINA WILL
CONTINUE SCA CONDITIONS OVER MARINE AREA (OCEAN AND DELAWARE BAY)
WIDESPREAD SCA CONDITIONS THROUGH THE REMAIN PORTION OF THE WEEKEND.
DEPENDING ON THE PATH OF THIS STORM...GALES ARE EVEN POSSIBLE
SATURDAY NIGHT INTO SUNDAY ON THE OCEAN AND LOWER DELAWARE BAY.
THIS SITUATION WILL BE RE- EXAMINED WITH LATER MODEL RUNS. A
SOUTHWEST FLOW BEHIND AN ADVANCING WARM FRONT IS EXPECTED TO SCA
BACK TO THE FORECAST WATERS ON TUESDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DRAG/MIKETTA 819
NEAR TERM...DRAG 819
SHORT TERM...DELISI
LONG TERM...MIKETTA
AVIATION...DELISI/DRAG/MIKETTA 819
MARINE...DELISI/DRAG/MIKETTA
AREA FORECAST DISCUSSION...UPDATED
NWS MIAMI FL
1250 PM EST THU FEB 14 2013
.AVIATION...
THE STATIONARY FRONT HAS MOVED BACK NORTH INTO THE LAKE OKEECHOBEE
AREA EARLY THIS AFTERNOON. THIS HAS ALLOWED FOR THE SKIES TO BECOME
PARTLY CLOUDY OVER MOST OF THE TAF SITES EARLY THIS
AFTERNOON...AND ALLOWED FOR THE EAST COAST SEA BREEZE TO SET UP
ALONG THE EAST COASTAL AREAS. THE EAST COAST SEA BREEZE WILL
CONTINUE TO PUSH SLOWLY INLAND THIS AFTERNOON ALLOWING FOR THE
WINDS AT KFLL TO REMAIN EASTERLY AT 5 TO 10 KNOTS...AND SWING TO A
EASTERLY DIRECTION AT KOPF TAF SITE AROUND 19Z AND THEN AT KMIA
TAF SITE AROUND 20Z. REST OF THE TAF SITES SHOULD REMAIN IN A
SOUTH TO SOUTHWEST DIRECTION THIS AFTERNOON AT 5 TO 10 KNOTS.
WITH THE EAST COAST SEA BREEZE SETTING UP ALONG THE EAST COAST
AREA AND THE SKIES BEING PARTLY CLOUDY...THIS WILL ALLOW FOR
SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP OVER THE EASTERN
AREAS OF THE CWA. SO HAVE INTRODUCE VCTS FOR ALL OF THE EAST COAST
TAF SITES UNTIL 01Z...EXCEPT FOR KPBI WHERE VCSH WILL REMAIN...DUE
TO THE FRONT LOCATED OVER THIS SITE. KAPF TAF SITE WILL ALSO ONLY
SEE VCSH FOR THIS AFTERNOON.
THE THUNDER THREAT OVER THE EAST COAST TAF SITES WILL COME TO AN
END AROUND 00Z TO 01Z TONIGHT...AS THE HEATING OF THE DAY IS LOST
AND THE WINDS BECOME MORE SOUTHWEST OVER THE TAF SITES AT 5 KNOTS
OR LESS.
AT THIS TIME THE VIS AND CEILING SHOULD REMAIN IN THE VFR
CONDITIONS OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS THAT DO
DEVELOP. IN THE SHOWERS AND THUNDERSTORMS THE VIS AND CEILING
COULD FALL DOWN INTO THE IFR CONDITIONS.
&&
...AVIATION...54/BNB
.PREV DISCUSSION... /ISSUED 815 AM EST THU FEB 14 2013/
..ISOLATED TSTORMS, SOME COULD CONTAIN STRONG WIND GUSTS AND
LOCALLY HEAVY RAINFALL...
UPDATE...WAVES OF HEAVY SHOWERS CONTINUE TO MOVE NE ACROSS
COLLIER TO PALM BEACH COUNTIES. ONLY ONE LIGHTNING STRIKE NOTED
JUST OFF THE COLLIER COAST A COUPLE OF HOURS AGO. GIVEN RADAR AND
EXPECTED TRENDS, HAVE INCREASED POPS ACROSS THE AREA. HRRR SHOWS A
GENERAL DECREASING TREND LATER THIS MORNING BEFORE THINGS REV BACK
UP AGAIN THIS AFTERNOON...AND WITH SLIGHTLY BETTER HEATING ACROSS
BROWARD AND MIAMI-DADE COUNTIES, TSTORMS COULD ERUPT ABOUT
ANYWHERE BUT BETTER CHANCES THERE. MORNING ANALYSIS INDICATES THE
POTENTIAL FOR A FEW STRONG TSTORMS WITH GUSTY WINDS TO AROUND 50
MPH. THERE IS SOME INCREASING INSTABILITY ALONG WITH AN INCOMING
SHORTWAVE OVER THE GULF OF MEXICO WHICH COULD IGNITE A FEW STRONG
TSTORMS, PARTICULARLY THIS AFTERNOON INTO EARLY THIS EVENING.
TEMPS WERE LOWERED A BIT ACROSS SE AREAS SINCE CLOUDS ARE
INCREASING FROM THE WEST. THEREFORE, MAX TEMPS IN THE LOWER 80S
ARE NOW FORECAST WITH MID-UPPER 70S LAKE OKEECHOBEE REGION.
&&
/GREGORIA
PREV DISCUSSION... /ISSUED 621 AM EST THU FEB 14 2013/
AVIATION...
COLD FRONT CURRENTLY NEAR A FORT LAUDERDALE TO EVERGLADES CITY
LINE AND CLEARLY DEFINED BY BROKEN LINE OF SHRA BEHIND THE BOUNDARY.
THE FRONT IS EXPECTED TO STALL ACROSS SOUTH FLORIDA BUT MODEL
GUIDANCE DIFFERS JUST WHERE THE BOUNDARY BECOMES STATIONARY AND
THIS WILL LIKELY PLAY HAVOC WITH THE WIND DIRECTION. AT ANY RATE,
INCREASED CLOUD COVER WILL OCCUR WITH CHANCES OF RAIN ALSO
INCREASING AT ALL TERMINALS THROUGH THE FORECAST WITH OCCASIONAL
MVFR CIG/VSBY AND BRIEF IFR CANNOT BE RULED OUT EITHER.
&&
KOB
PREV DISCUSSION... /ISSUED 333 AM EST THU FEB 14 2013/
SHORT TERM...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE INTO SOUTH FLORIDA AS
TODAY PROGRESSES. MOISTURE ADVECTION WILL TAKE PLACE THROUGHOUT THE
DAY LEADING TO AN INCREASED CHANCE OF RAIN. SINCE THIS FRONT WILL
STALL OUT, IT LOOKS LIKE IT WILL BE A CLOUDY AND WET 48 HOUR
PERIOD WITH SOME STEADY RAIN ALONG THE FRONT AS WELL AS THE
POTENTIAL FOR SOME HEAVIER SHOWERS AND A FEW THUNDERSTORMS.
INSTABILITY WILL BE RATHER LOW THROUGHOUT THE PERIOD WHICH WILL
LIMIT THE THUNDERSTORM ACTIVITY, HOWEVER SOME EMBEDDED
THUNDERSTORMS COULD DEVELOP. THE MAIN CONCERN WITH THIS FRONT WILL
BE THE POTENTIAL FOR HEAVY RAIN. MODEL CONCENSUS IS SHOWING A
WIDESPREAD AREA OF 1 TO 2 INCHES OF RAIN TODAY INTO FRIDAY. SOME
AREAS COULD SEE LOCALIZED HIGHER TOTALS IN EXCESS OF 3 INCHES
WHERE THE HEAVIER SHOWERS OR THUNDERSTORMS SET UP. THIS COULD RESULT
IN ISOLATED URBAN FLOODING. HOWEVER, WIDESPREAD FLOOD PROBLEMS ARE
NOT EXPECTED DUE TO THE DRY SPELL WE HAVE BEEN IN.
LONG TERM...
A STRONGER FRONT WILL BEGIN TO HELP MOVE ALL OF THE SHOWER AND
THUNDERSTORM ACTIVITY OUT OF THE REGION BY FRIDAY NIGHT INTO EARLY
SATURDAY MORNING. BEHIND THIS FRONT A STRONG AREA OF HIGH
PRESSURE WILL BUILD IN FROM THE NORTH BRINGING IN MUCH COLDER
TEMPERATURES TO THE REGION. THE STRONGEST PUSH OF COLD AIR WILL
MOVE INTO THE REGION SATURDAY NIGHT AND SUNDAY. THE EXACT TIMING
OF THIS IS STILL UNCERTAIN AS THE GFS IS SLIGHTLY SLOWER AND A
LITTLE BIT WARMER ON SATURDAY NIGHT INTO SUNDAY, HOWEVER IT HAS
BEEN TRENDING TOWARDS THE QUICKER AND COLDER ECMWF SOLUTION. THE
FORECAST IS TRENDED TOWARDS THE ECMWF WHICH WOULD DROP TEMPERATURES
INTO THE MID 30S IN GLADES AND HENDRY COUNTIES ON BOTH SUNDAY AND
MONDAY MORNING. THERE COULD BE ISOLATED POCKETS OF TEMPERATURES
DROPPING TO NEAR FREEZING IN THE COLDER LOCATIONS. WE WILL
CONTINUE TO MONITOR THESE TRENDS. TEMPERATURES ON SUNDAY MORNING
ACROSS THE SOUTHEASTERN METRO AREAS WILL BE IN THE MID TO UPPER
40S. COLD AIR ADVECTION WILL CONTINUE DURING THE DAY ON SUNDAY AS
MANY AREAS WILL REMAIN IN THE MID TO UPPER 60S FOR DAYTIME HIGHS.
THIS AREA OF HIGH PRESSURE WILL MOVE EAST OF THE AREA EARLY NEXT
WEEK RESULTING MODERATING TEMPERATURES BY MONDAY AFTERNOON INTO
TUESDAY WITH DRY CONDITIONS.
MARINE...
A COLD FRONT WILL STALL OUT OVER THE ATLANTIC AND GULF WATERS
TODAY. THIS FRONT WILL REMAIN IN PLACE THROUGH FRIDAY CREATING A
CHANCE OF SHOWERS AND A FEW THUNDERSTORMS. WINDS WILL REMAIN OUT
OF THE SOUTH AT 10 TO 15 KNOTS THIS AFTERNOON. THE FRONT WILL MOVE
TO THE SOUTH OF THE REGION ON FRIDAY NIGHT INTO SATURDAY. GUSTY
NORTHWEST WINDS BEHIND THE FRONT MAY CREATE HAZARDOUS MARINE
CONDITIONS THIS WEEKEND.
FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES WILL REMAIN ABOVE CRITICAL VALUES
ON THURSDAY NIGHT INTO FRIDAY. THESE VALUES ARE EXPECTED BE MUCH
LOWER BEHIND THE FRONT ON SUNDAY AND MONDAY AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 79 63 76 60 / 80 70 50 40
FORT LAUDERDALE 83 67 77 62 / 70 70 50 50
MIAMI 83 66 80 63 / 70 70 50 50
NAPLES 79 61 75 58 / 90 70 50 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...55/CWC
AVIATION/RADAR...30/KOB
AREA FORECAST DISCUSSION
NWS MIAMI FL
815 AM EST THU FEB 14 2013
...ISOLATED TSTORMS, SOME COULD CONTAIN STRONG WIND GUSTS AND
LOCALLY HEAVY RAINFALL...
.UPDATE...WAVES OF HEAVY SHOWERS CONTINUE TO MOVE NE ACROSS
COLLIER TO PALM BEACH COUNTIES. ONLY ONE LIGHTNING STRIKE NOTED
JUST OFF THE COLLIER COAST A COUPLE OF HOURS AGO. GIVEN RADAR AND
EXPECTED TRENDS, HAVE INCREASED POPS ACROSS THE AREA. HRRR SHOWS A
GENERAL DECREASING TREND LATER THIS MORNING BEFORE THINGS REV BACK
UP AGAIN THIS AFTERNOON...AND WITH SLIGHTLY BETTER HEATING ACROSS
BROWARD AND MIAMI-DADE COUNTIES, TSTORMS COULD ERUPT ABOUT
ANYWHERE BUT BETTER CHANCES THERE. MORNING ANALYSIS INDICATES THE
POTENTIAL FOR A FEW STRONG TSTORMS WITH GUSTY WINDS TO AROUND 50
MPH. THERE IS SOME INCREASING INSTABILITY ALONG WITH AN INCOMING
SHORTWAVE OVER THE GULF OF MEXICO WHICH COULD IGNITE A FEW STRONG
TSTORMS, PARTICULARLY THIS AFTERNOON INTO EARLY THIS EVENING.
TEMPS WERE LOWERED A BIT ACROSS SE AREAS SINCE CLOUDS ARE
INCREASING FROM THE WEST. THEREFORE, MAX TEMPS IN THE LOWER 80S
ARE NOW FORECAST WITH MID-UPPER 70S LAKE OKEECHOBEE REGION.
/GREGORIA
&&
.PREV DISCUSSION... /ISSUED 621 AM EST THU FEB 14 2013/
AVIATION...
COLD FRONT CURRENTLY NEAR A FORT LAUDERDALE TO EVERGLADES CITY
LINE AND CLEARLY DEFINED BY BROKEN LINE OF SHRA BEHIND THE BOUNDARY.
THE FRONT IS EXPECTED TO STALL ACROSS SOUTH FLORIDA BUT MODEL
GUIDANCE DIFFERS JUST WHERE THE BOUNDARY BECOMES STATIONARY AND
THIS WILL LIKELY PLAY HAVOC WITH THE WIND DIRECTION. AT ANY RATE,
INCREASED CLOUD COVER WILL OCCUR WITH CHANCES OF RAIN ALSO
INCREASING AT ALL TERMINALS THROUGH THE FORECAST WITH OCCASIONAL
MVFR CIG/VSBY AND BRIEF IFR CANNOT BE RULED OUT EITHER.
KOB
PREV DISCUSSION... /ISSUED 333 AM EST THU FEB 14 2013/
SHORT TERM...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE INTO SOUTH FLORIDA AS
TODAY PROGRESSES. MOISTURE ADVECTION WILL TAKE PLACE THROUGHOUT THE
DAY LEADING TO AN INCREASED CHANCE OF RAIN. SINCE THIS FRONT WILL
STALL OUT, IT LOOKS LIKE IT WILL BE A CLOUDY AND WET 48 HOUR
PERIOD WITH SOME STEADY RAIN ALONG THE FRONT AS WELL AS THE
POTENTIAL FOR SOME HEAVIER SHOWERS AND A FEW THUNDERSTORMS.
INSTABILITY WILL BE RATHER LOW THROUGHOUT THE PERIOD WHICH WILL
LIMIT THE THUNDERSTORM ACTIVITY, HOWEVER SOME EMBEDDED
THUNDERSTORMS COULD DEVELOP. THE MAIN CONCERN WITH THIS FRONT WILL
BE THE POTENTIAL FOR HEAVY RAIN. MODEL CONCENSUS IS SHOWING A
WIDESPREAD AREA OF 1 TO 2 INCHES OF RAIN TODAY INTO FRIDAY. SOME
AREAS COULD SEE LOCALIZED HIGHER TOTALS IN EXCESS OF 3 INCHES
WHERE THE HEAVIER SHOWERS OR THUNDERSTORMS SET UP. THIS COULD RESULT
IN ISOLATED URBAN FLOODING. HOWEVER, WIDESPREAD FLOOD PROBLEMS ARE
NOT EXPECTED DUE TO THE DRY SPELL WE HAVE BEEN IN.
LONG TERM...
A STRONGER FRONT WILL BEGIN TO HELP MOVE ALL OF THE SHOWER AND
THUNDERSTORM ACTIVITY OUT OF THE REGION BY FRIDAY NIGHT INTO EARLY
SATURDAY MORNING. BEHIND THIS FRONT A STRONG AREA OF HIGH
PRESSURE WILL BUILD IN FROM THE NORTH BRINGING IN MUCH COLDER
TEMPERATURES TO THE REGION. THE STRONGEST PUSH OF COLD AIR WILL
MOVE INTO THE REGION SATURDAY NIGHT AND SUNDAY. THE EXACT TIMING
OF THIS IS STILL UNCERTAIN AS THE GFS IS SLIGHTLY SLOWER AND A
LITTLE BIT WARMER ON SATURDAY NIGHT INTO SUNDAY, HOWEVER IT HAS
BEEN TRENDING TOWARDS THE QUICKER AND COLDER ECMWF SOLUTION. THE
FORECAST IS TRENDED TOWARDS THE ECMWF WHICH WOULD DROP TEMPERATURES
INTO THE MID 30S IN GLADES AND HENDRY COUNTIES ON BOTH SUNDAY AND
MONDAY MORNING. THERE COULD BE ISOLATED POCKETS OF TEMPERATURES
DROPPING TO NEAR FREEZING IN THE COLDER LOCATIONS. WE WILL
CONTINUE TO MONITOR THESE TRENDS. TEMPERATURES ON SUNDAY MORNING
ACROSS THE SOUTHEASTERN METRO AREAS WILL BE IN THE MID TO UPPER
40S. COLD AIR ADVECTION WILL CONTINUE DURING THE DAY ON SUNDAY AS
MANY AREAS WILL REMAIN IN THE MID TO UPPER 60S FOR DAYTIME HIGHS.
THIS AREA OF HIGH PRESSURE WILL MOVE EAST OF THE AREA EARLY NEXT
WEEK RESULTING MODERATING TEMPERATURES BY MONDAY AFTERNOON INTO
TUESDAY WITH DRY CONDITIONS.
MARINE...
A COLD FRONT WILL STALL OUT OVER THE ATLANTIC AND GULF WATERS
TODAY. THIS FRONT WILL REMAIN IN PLACE THROUGH FRIDAY CREATING A
CHANCE OF SHOWERS AND A FEW THUNDERSTORMS. WINDS WILL REMAIN OUT
OF THE SOUTH AT 10 TO 15 KNOTS THIS AFTERNOON. THE FRONT WILL MOVE
TO THE SOUTH OF THE REGION ON FRIDAY NIGHT INTO SATURDAY. GUSTY
NORTHWEST WINDS BEHIND THE FRONT MAY CREATE HAZARDOUS MARINE
CONDITIONS THIS WEEKEND.
FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES WILL REMAIN ABOVE CRITICAL VALUES
ON THURSDAY NIGHT INTO FRIDAY. THESE VALUES ARE EXPECTED BE MUCH
LOWER BEHIND THE FRONT ON SUNDAY AND MONDAY AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 79 63 76 60 / 80 70 50 40
FORT LAUDERDALE 83 67 77 62 / 70 70 50 50
MIAMI 83 66 80 63 / 70 70 50 50
NAPLES 79 61 75 58 / 90 70 50 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
335 AM EST THU FEB 14 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOW BROAD LONGWAVE TROUGHING IN
PLACE OVER MUCH OF THE CONUS. FEATURE EMBEDDED WITHIN THIS LARGER
SCALE FLOW THAT WILL HAVE THE MOST SHORT TERM INFLUENCE IS A
SHORTWAVE IMPULSE EJECTING EASTWARD FROM THE SOUTHERN
PLAINS/NORTHERN MEXICO. THIS FEATURE WILL MOVE SLOWLY EASTWARD
TOWARD THE FL PENINSULA INTO FRIDAY KEEPING OUR AREA WITHIN IN A
REGION OF BROAD SYNOPTIC ASCENT/QG FORCING. WV IMAGERY SHOWS THAT WE
HAVE NO LACK OF MID/UPPER LEVEL MOISTURE STREAMING ACROSS THE
NORTHERN GULF AND CENTRAL/NORTHERN FL PENINSULA FOR THIS BROAD LIFT
TO ACT ON.
AT THE SURFACE...COLD FRONT CONTINUES TO VERY SLOW DRIFT SOUTH AND
EAST INTO THE SOUTHERN FLORIDA PENINSULA. THE BOUNDARY HAS NOW
CLEARED ALL OF OUR FORECAST AREA WITH COOLER AND DRIER LOW LEVEL AIR
TRYING TO FILTER IN FROM THE NORTH. THIS DRY AIR WILL ONLY BE IN THE
VERY LOWEST LEVELS...AND SHOWERS WILL REMAIN IN THE FORECAST...EVEN
IN THE POST-FRONTAL ENVIRONMENT. REGIONAL RADARS...SHOW A SCATTERING
OF LIGHT SHOWER ACTIVITY ACROSS THE REGION EARLY THIS MORNING...WITH
A FEW HEAVIER CELLS DOWN OVER THE SOUTHERN PENINSULA IN CLOSER
PROXIMITY TO THE FRONTAL FOCUS.
&&
.SHORT TERM (TODAY THROUGH SATURDAY)...
TODAY/TONIGHT...
SURFACE BOUNDARY WILL BECOME STALLED THIS MORNING ACROSS THE SE GULF
AND FAR SOUTHERN FL PENINSULA...AND THEN REMAIN IN PLACE THROUGH
TONIGHT. MID/UPPER LEVEL SHORTWAVE IMPULSE WILL GRADUALLY ELONGATE
AND MOVE EASTWARD ACROSS THE NORTHERN GULF TOWARD THE REGION. THE
RAINFALL FORECAST REMAINS A TRICKY ONE AS THE FORCING MECHANISMS ARE
ALL RATHER BROAD WITH NOTHING OBVIOUS TO FOCUS THE LIFT IN ONE PLACE
VS ANOTHER. OVERALL...STILL FEEL THE MOST WIDESPREAD SHOWERS
ACTIVITY WILL EVENTUALLY DEVELOP BY LATER TODAY AND INTO THE
OVERNIGHT ALONG AND TO THE SOUTH OF THE I-4 CORRIDOR...WHERE LARGE
SCALE QG FORCING WILL BECOME COINCIDENT WITH WELL DEFINED DIFFLUENCE
ALOFT...AND AT LEAST SOME LOW LEVEL UPGLIDE TO THE NORTH OF THE
SURFACE BOUNDARY. FOR THIS MORNING...ONE DEPARTING JET STREAK UP THE
EASTERN SEABOARD IS SUPPORTING A SWATH OF GOOD DIVERGENCE ALOFT AND
A BAND OF SHOWERS/RAIN ACROSS APALACHEE BAY AND THE FL BIG BEND.
GUIDANCE SUGGESTS THAT ALTHOUGH THIS DIVERGENCE WILL BE PULLING AWAY
WITH TIME...INCREASING CHANCES FOR SHOWERS WILL ONCE AGAIN ARRIVE
ACROSS OUR NORTHERN NATURE COAST ZONES FOR A TIME THIS MORNING. BY
THE AFTERNOON...THESE DYNAMICS WILL BE ESSENTIALLY GONE AND THINK
THE BEST FOCUS FOR SHOWERS SHIFTS SOUTHWARD. HAVE CHANCE POPS THIS
MORNING FOR ALL WITH A BAND OF LIKELY UP TOWARD LEVY COUNTY FOR
REASONS DISCUSSED ABOVE. THEREAFTER FOR THE AFTERNOON AND EVENING
KEPT CHANCE POPS NORTH OF TAMPA BAY WITH LIKELY TO CATEGORICAL RAIN
CHANCES ALONG THE I-4 CORRIDOR AND SOUTHWARD. TEMPERATURES WILL
DEPEND HIGHLY ON THE EVENTUAL RAINFALL PATTERNS AND ARRIVAL
TIMING...BUT MID 60S FAR NORTH RANGING TO LOWER 70S MID ZONES...AND
MID/UPPER 70S SOUTH SHOULD WORK WELL. LOW TEMPS TONIGHT WILL RANGE
FROM THE 40S FAR NORTH TO THE LOW/MID 50 MID ZONES...AND MID 50S TO
AROUND 60 FAR SOUTH. SOME OF THE STATISTICAL GUIDANCE WANTS TO BRING
TEMPS DOWN INTO THE 30S FAR NORTH...BUT FEEL WITH THE AMOUNT OF
CLOUDS AND POTENTIAL FOR AT LEAST SOME RESIDUAL SHOWERS
ACTIVITY...EVEN AS FAR NORTH AS LEVY COUNTY...THAT 30S ARE UNLIKELY.
FRIDAY/FRIDAY NIGHT...
SHORTWAVE AXIS PASSES TO OUR EAST EARLY IN THE DAY WITH A DECLINE IN
THE LARGE SCALE FORCING. UPPER JET CONFIGURATION FAVORS LESS AND
LESS DIFFLUENCE ALOFT AS WELL. EXPECT A SCATTERING OF SHOWERS TO
STILL BE ONGOING DURING THE MORNING HOURS...ESPECIALLY SOUTH AND
EAST OF TAMPA BAY IN CLOSER PROXIMITY TO THE SURFACE BOUNDARY. THIS
ACTIVITY SHOULD SLOWLY PIVOT EASTWARD AND AWAY FROM OUR ZONES
LATER FRIDAY AND ESPECIALLY FRIDAY EVENING AS A BIG PATTERN CHANGE
FOR THE UPCOMING WEEKEND BEGINS TO RAPIDLY EVOLVE TO OUR NORTHWEST.
SO...SCATTERED SHOWERS (BUT NOT A WASHOUT) EXPECTED FROM TAMPA
BAY/POLK COUNTY SOUTHWARD ON FRIDAY...WITH THIS ACTIVITY ENDING FOR
ALL ZONES DURING FRIDAY NIGHT. UPPER LEVEL PATTERN WILL BE
AMPLIFYING OVER THE EASTERN HALF OF THE NATION ON FRIDAY...WITH A
STRONG SHORTWAVE IMPULSE WORKING DOWN THE BACKSIDE OF THE TROUGH.
THIS ENERGY WILL ACT TO REALLY SHARPEN THE FLOW FRIDAY NIGHT INTO
SATURDAY ACROSS THE SOUTHEASTERN STATES/FL PENINSULA. FIRST BOUNDARY
ASSOCIATED WITH THIS TROUGH LOOKS TO QUICKLY CROSS THE AREA FRIDAY
NIGHT...WITH CAA INTENSIFYING AFTER MIDNIGHT. WILL SEE WIDESPREAD
TEMPS IN THE 40S BY EARLY SATURDAY MORNING. SOME UPPER 30S ARE
LIKELY ACROSS THE NATURE COAST...AND 50S AT THE IMMEDIATE COAST FROM
PINELLAS COUNTY SOUTHWARD.
SATURDAY...
SHARP SHORTWAVE IMPULSE EJECTS ACROSS THE PENINSULA SURGING A
REINFORCING COLD FRONT ACROSS THE AREA DURING THE DAY. THIS FRONT
WILL HAVE A DRY PASSAGE...BUT WILL DELIVER ONE OF THE COLDEST (IF
NOT THE COLDEST) OVERALL LOW LEVEL COLUMNS OF THE WINTER SO FAR.
850MB TEMPS WILL DROP BELOW ZERO ACROSS AT LEAST THE CENTRAL AND
NORTHERN PORTIONS OF THE FORECAST AREA. GFS 850MB TEMPS BY SATURDAY
EVENING ARE ON THE ORDER OF 3-3.5 STANDARD DEVIATIONS BELOW CLIMO
FOR MID FEBRUARY. THE GFS TENDS TO HAVE A COLD BIAS IN ITS 850MB
TEMPS...BUT EVEN TAKING THIS BIAS INTO CONSIDERATION...A BIG COOL
DOWN IN IN STORE FOR THE WEEKEND. WINDS WILL BECOME GUSTY SATURDAY
AFTERNOON BEHIND THIS SECONDARY FRONT...ESPECIALLY CLOSE TO THE
COAST...AND IT WILL FEEL QUITE COOL FOR OUTDOOR ACTIVITIES. MORE ON
THIS BRIEF...BUT SHARP COLD SNAP IN THE LONG RANGE DISCUSSION BELOW.
&&
.LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)...
THE MAIN STORY IN THE EXTENDED FORECAST CONTINUES TO BE THE COLD
TEMPERATURES OVER THE UPCOMING WEEKEND. WE WILL LIKELY BE DEALING
WITH FREEZING TEMPERATURES FOR PORTIONS OF OUR AREA BOTH SATURDAY
NIGHT AND SUNDAY NIGHT. SATURDAY NIGHT WILL BE AN ADVECTIVE FREEZE
WITH SOME WIND CHILL ISSUES AS WELL. SUNDAY NIGHT WILL BE MORE OF A
RADIATIONAL COOLING FREEZE. TEMPERATURES BOTH NIGHTS COULD END UP
QUITE SIMILAR...BUT IT WILL PROBABLY FEEL COLDER SATURDAY NIGHT WITH
WINDS AROUND 10 MPH. RIGHT NOW EXPECT WIDESPREAD TEMPERATURES
BETWEEN 28 AND 32 DEGREES BOTH NIGHTS FROM ABOUT HERNANDO COUNTY
NORTHWARD. SOUTH OF THERE...I AM LEANING TOWARD MID 30S OVER THE
INTERIOR. IF SKIES STAY CLEAR SUNDAY NIGHT AND WE COMPLETELY
DECOUPLE LEADING TO CALM WINDS...FREEZING TEMPERATURES WILL EXTEND
MUCH FARTHER SOUTH. THIS IS ALL STILL BEYOND 72 HOURS OUT SO NO
WATCHES ARE NEEDED YET AND THERE IS STILL PLENTY OF TIME TO REFINE
THE FORECAST.
AS QUICK AS THE COLD AIR MOVES IN...IT MOVES BACK OUT. SUNDAY WILL
BE THE COLDEST DAY WITH HIGHS ONLY IN THE UPPER 50S TO NEAR 60 FROM
TAMPA BAY NORTH AND IN THE LOWER TO MIDDLE 60S WELL TO THE SOUTH. ON
MONDAY WE WILL BE 10 DEGREES WARMER THAN THAT WHICH BRINGS US BACK
TO NEAR NORMAL. WE WILL BE IN A VERY PROGRESSIVE PATTERN THROUGH
MID-WEEK AND BEYOND WITH COLD FRONTS ARRIVING ABOUT EVERY THIRD DAY.
THE NEXT CHANCE OF RAIN WILL BE LATE TUESDAY AND TUESDAY NIGHT
FOLLOWED BY DRIER...AND SOMEWHAT COOLER AIR ON WEDNESDAY.
&&
.AVIATION...
THE LAST BATCH OF HEAVIER SHOWERS IS MOVING THROUGH FMY AND RSW NOW.
THE REST OF THE REGION SHOULD SEE MAINLY VFR CONDITIONS THROUGH MID
AFTERNOON OR SO. RAIN IS EXPECTED TO REDEVELOP OVER THE GULF LATER
WHICH SHOULD BRING MVFR CEILINGS TO ALL TERMINALS THROUGH THE
EVENING HOURS. THE NORTHERN TERMINALS HAVE THE BEST CHANCE AT
RETURNING TO VFR AFTER 00Z WHILE THE SOUTHERN TERMINALS COULD SEE AN
EXTENDED PERIOD OF MVFR OR PERHAPS EVEN IFR CEILINGS LASTING INTO
THE MORNING HOURS FRIDAY.
&&
.MARINE...
FRONTAL BOUNDARY WILL STALL JUST SOUTH OF THE FORECAST WATERS
THROUGH FRIDAY HELPING TO KEEP PERIODS OF RAIN/SHOWERS ACROSS THE
EASTERN GULF THE NEXT 24 HOURS. NORTH TO NORTHEAST FLOW WILL
OCCASIONALLY APPROACH CAUTIONARY LEVELS...ESPECIALLY SOUTH OF TAMPA
BAY THROUGH THIS EVENING WITH ALL ZONES REMAINING BELOW HEADLINE
CRITERIA ON FRIDAY. ANOTHER STRONGER BUT DRY FRONT WILL QUICKLY MOVE
THROUGH THE EASTERN GULF OF MEXICO FRIDAY NIGHT AND SATURDAY MORNING
WITH WINDS AND SEAS RAPIDLY BUILDING TO ADVISORY LEVELS FROM THE
NORTHWEST FOR MUCH OF SATURDAY AND SATURDAY NIGHT. WINDS AND WAVES
WILL GRADUALLY SUBSIDE INTO SUNDAY AS HIGH PRESSURE BUILDS OVER THE
REGION.
&&
.FIRE WEATHER...
RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL LEVELS TODAY. THE
ONE CONCERN WILL HOWEVER BE FOR LOW DISPERSION INDICES THROUGH THE
DAY. SOMEWHAT DRIER AIR WILL BEGIN TO ARRIVE OVER THE NORTHERN ZONES
FOR FRIDAY AND A BRIEF PERIOD OF RELATIVE HUMIDITY BELOW 35 PERCENT
IS POSSIBLE FOR LEVY/CITRUS AND SUMTER COUNTIES. DESPITE THE DRY AIR
UP NORTH...ERC VALUES ARE LOW...AND DISPERSION INDICES WILL REMAIN
LOW AS WELL. THESE CONDITIONS SHOULD PREVENT ANY RED FLAG CONDITIONS
FROM BEING MET. MUCH DRIER AIR ARRIVES FOR ALL ZONES ON SATURDAY...
ALONG WITH GUSTY NORTHWEST WINDS BY THE AFTERNOON HOURS. WILL NEED
TO MONITOR CONDITIONS CLOSELY FOR SATURDAY AS LOW RELATIVE
HUMIDITY...GUSTY WINDS...AND HIGH DISPERSIONS MAY ALLOW FOR SOME
BRIEF RED FLAG CONDITIONS.
&&
PRELIMINARY POINT TEMPS/POPS...
TPA 69 55 69 51 / 80 50 30 10
FMY 76 62 73 55 / 90 70 50 30
GIF 72 53 71 47 / 80 60 30 10
SRQ 69 56 70 52 / 80 60 30 20
BKV 68 50 70 41 / 60 50 20 10
SPG 68 58 69 56 / 80 60 30 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR CHARLOTTE-
LEE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA
LONG TERM/AVIATION/DECISION SUPPORT SERVICES...JILLSON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
320 PM CST THU FEB 14 2013
.SYNOPSIS...
18Z SURFACE ANALYSIS INDICATED LOW PRESSURE OVER NORTHERN LOWER MI
WITH A TROUGH OR WEAK COLD FRONT REACHING SOUTH-SOUTHWEST ACROSS
IL...MO INTO EASTERN OK. A SECOND REINFORCING COLD FRONT EXTENDED
WEST FROM THE LOW ACROSS WI TO ALONG THE IA/MN BORDER. SOUTH OF THIS
FRONT...TEMPERATURES WERE IN THE 30S TO LOWER 40S WITH BRISK W-NW
WINDS ACROSS THE FORECAST AREA. ALOFT...A BROAD CYCLONIC FLOW
ENCOMPASSED THE EASTERN 2/3RDS OF THE CONTINENTAL U.S. THERE WERE A
SERIES OF SHORTWAVES EMBEDDED IN THIS FLOW FROM THE GREAT LAKES TO
THE CANADIAN ROCKIES. THE FOCUS IN THE SHORT TERM IS A VORT MAX
EVIDENT ON SATELLITE WV IMAGES OVER N CENTRAL IA...WHERE AREA RADARS
AND SURFACE REPORTS WERE INDICATING SNOW SHOWERS.
&&
.SHORT TERM...TONIGHT AND FRIDAY...
MAIN FOCUS IS ON THE SNOW SHOWERS THAT WILL OVERSPREAD THE AREA
LATE THIS AFTERNOON AND EVENING...THEN COOLER TEMPERATURES AND
POTENTIAL FLURRIES THROUGH FRIDAY.
AN AXIS OF ROTATION SEEN IN RECENT KDMX 88D LOOPS INDICATED THE
UPSTREAM VORT MAX WAS CENTERED ROUGHLY NORTH OF WEBSTER CITY AT 20Z.
THIS WAS WELL SOUTH OF THE OPERATIONAL NAM...GFS AND ECMWF TRACKS
FROM THIS MORNING. THE RECENT RAP RUNS APPEARED TO HAVE A DECENT
CAPTURE OF THIS VORT CENTER AND WILL FOLLOW ITS OVERALL
SOUTHEASTWARD TRACK. THIS WILL SEND THE UPSTREAM SNOW SHOWERS...
TRENDING HEAVIEST ALONG AND NORTH OF THE VORT MAX...SOUTHEAST
THROUGH THE EAST CENTRAL IA AND THEN W CENTRAL IL OVER THE NEXT
SEVERAL HOURS. COLD ADVECTION ALOFT WAS SHOWN LEADING TO STEEP MID
LEVEL LAPSE RATES ON THE ORDER OF 7 TO 8 DEG C/KM IN THIS MORNING/S
MODEL RUNS. THIS...COMBINED WITH THE UPPER LEVEL FORCING AND LIFT
ALONG THE SOUTHWARD MOVING COLD FRONT WILL SUPPORT CONTINUED LIGHT
TO MODERATE SNOW SHOWERS AND AT LEAST LIGHT ACCUMULATIONS. THE HIGH
RES RAP CONTINUES TO INDICATE QPF VALUES IN THE RANGE OF .2 TO .3
INCHES AS SNOW SHOWERS TRACK FROM ABOUT CID THROUGH THE QUAD CITIES
TO NEAR KEWANEE BETWEEN 23Z AND 05Z AND HAVE LIKELY POPS ALONG THIS
AXIS. WHILE THIS LOOKS OVERDONE BASED ON MEAGER PRECIPITATION
AMOUNTS REPORTED SO FAR AT AUTOMATED UPSTREAM SITES...CANNOT RULE
OUT BANDS OF 1 TO POSSIBLY 2 INCH SNOW ACCUMULATIONS IF THE
CONVECTION TAPS INTO THE DEEPER INSTABILITY OVER THE NEXT SEVERAL
HOURS. BASED ON THE INITIAL WARM LOW LEVELS AND TEMPERATURES IN
THE 30S TO LOWER 40S LEADING TO A RAIN/SNOW MIX AT ONSET...WILL
STAY CLOSE TO A MORE CONSERVATIVE .5 TO 1 INCH SNOWFALL RANGE FOR
NOW AND WATCH TRENDS CLOSELY.
THE CURRENT PACE OF THE VORT MAX SHOULD SEND THE SHOWERS EAST OF THE
AREA BY MID EVENING...AND HAVE ONLY SLIGHT CHANCE POPS AFTER
MIDNIGHT IN THE EAST AND SOUTHEAST. THE COLD FRONT SHOULD SLIDE
THROUGH THE ENTIRE AREA BY MIDNIGHT...FOLLOWED BY PARTIAL CLEARING
BASED ON SATELLITE TRENDS. GUIDANCE LOWS BY SUNRISE IN THE MID TEENS
NORTH TO MID 20S SOUTH LOOK REASONABLE.
FRIDAY...WILL KEEP A MENTION OF SCATTERED FLURRIES GOING IN THE
FORECAST BASED ON THE STREAM OF WEAK IMPULSES AND MID LEVEL MOISTURE
IN THE CYCLONIC FLOW ALOFT. CLOUD COVER AND COLD AIR ADVECTION
SHOULD LIMIT THE DIURNAL TEMPERATURE RISE. HAVE STAYED CLOSE TO
THE PREVIOUS FORECAST AND LATEST MODEL GUIDANCE WITH HIGHS
RANGING FROM THE LOWER 20S NORTH TO LOWER 30S SOUTH.
SHEETS
.LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY
FRIDAY NIGHT AND SATURDAY WE REMAIN IN THE NORTHWEST CYCLONIC FLOW
AND STEEP MID LEVEL LAPSE RATES WITH ENOUGH LOW LEVEL MOISTURE TO
ALLOW FOR FLURRIES DURING THE OVERNIGHT AND SATURDAY MORNING. WE
ALSO HAVE SOME UPPER LEVEL VORT MAXES THAT SHOULD ALSO HELP TO
TRIGGER THESE FLURRIES. THERE IS NOT REALLY ENOUGH MOISTURE FOR MORE
THAN THAT...THOUGH A DUSTING IS POSSIBLE IF REPEAT ACTIVITY AFFECTS
THE SAME AREA. TEMPERATURES TO REMAIN COLD THROUGH SATURDAY WITH
HIGHS SATURDAY IN THE 20S TO AROUND 30. WARMED MINS FRIDAY NIGHT DUE
TO THE EXTRA CLOUD COVER AND RANGE FROM 10-20.
STRONG WARM AIR ADVECTION SETS IN OVER THE AREA AT 850MB SATURDAY
NIGHT AND SUNDAY. THIS IS LIKELY TO BRING ANOTHER BAND OF CLOUD
COVER ACROSS THE AREA OVERNIGHT AND SUNDAY MORNING. SATURDAY NIGHT
MINS ARE LIKELY TO NOT SHOW MUCH CHANGE YET AS MOST OF THE WARMING
IS ALOFT. SUNDAY HOWEVER WE ARE LIKELY TO SEE A BIG WARM-UP WITH
HIGHS IN THE MID 30S NORTHEAST TO THE UPPER 40S SOUTHWEST.
TEMPERATURES APPROACHING 50 ARE POSSIBLE IF WE CAN CLEAR OUT AND MIX
DEEPLY ENOUGH.
THE NEXT PUZZLE OF THE DAY IS MONDAY AND MONDAY NIGHT AS OUR NEXT
STRONG STORM SYSTEM CROSSES THE MIDWEST. A RELATIVELY SHALLOW
LONGWAVE TROUGH MOVES ACROSS THE AREA WITH TWO SEPARATE PIECES OF
ENERGY...ONE FARTHER NORTH THAT GENERATES A SURFACE LOW OVER
SOUTHERN MINNESOTA BY MONDAY MORNING. ANOTHER PIECE OF ENERGY IS
OVER NEW MEXICO WHICH GENERATES A SURFACE LOW OVER OKLAHOMA AT THE
SAME TIME. THIS SYSTEM SWEEPS OUT ACROSS THE MIDWEST MONDAY AND
MONDAY NIGHT. MODELS HAVE BEEN VARYING ON HOW WELL PHASED THESE
SYSTEMS WILL BE OVER THE PAST COUPLE DAYS AS WELL AS HOW MUCH ENERGY
WILL BE WITH EACH. THUS...THE IMPACT FOR OUR CWA HAS VARIED FROM
DRY TO A RAIN/SNOW MIX. FOR NOW MODELS ARE COMING IN A LITTLE
SLOWER AND STRONGER...AND ARE BRINGING MORE MOISTURE AND WARMTH INTO
THE AREA. THUS...HAVE RAISED POPS THROUGH THE PERIOD. ALSO...HAVE
CONVERTED MONDAY TO NEARLY ALL RAIN...WITH JUST A RAIN SNOW MIX
ACROSS THE NORTH. MONDAY NIGHT WE GRADUALLY SWITCH TO ALL
SNOW...BUT THE TIMING IS STILL VERY MUCH UP IN THE AIR. DUE TO THE
START BEING ALL RAIN...SNOWFALL AMOUNTS WILL BE LIGHT.
TUESDAY AND WEDNESDAY ARE RELATIVELY QUIET WITH A STRONG SURFACE
RIDGE BUILDING INTO THE AREA FOR DRY AND COLD CONDITIONS. IN
FACT...IF WE CAN GET DECENT RADIATIONAL CONDITIONS FOR TUESDAY NIGHT
MIN TEMPS COULD DIP INTO THE SINGLE DIGITS OVER A FAIRLY LARGE
PORTION OF THE AREA. HOWEVER...THIS IS STILL SOMEWHAT QUESTIONABLE
AND HAVE STAYED A LITTLE WARMER FOR NOW.
THE BIG QUESTION OF THE FORECAST COMES THURSDAY. FOR SEVERAL MODEL
RUNS NOW...THE ECMWF AND GFS HAVE BEEN ADVERTISING A VERY STRONG
STORM FOR THE MIDWEST ON THURSDAY AND FRIDAY. THERE IS REMARKABLE
CONSISTENCY AND CONFIDENCE IS GROWING THAT SOMEWHERE IN THE MIDWEST
THERE WILL BE A MAJOR WINTER STORM...IF NOT A BLIZZARD.
HOWEVER...WHETHER OUR AREA WILL BE AFFECTED OR NOT IS VERY MUCH IN
QUESTION. WE CURRENTLY HAVE DIFFERING MODEL SOLUTIONS...ONE OF WHICH
DEPICTS THE WINTER STORM AFFECTING THE CWA WITH MAJOR SNOW
ACCUMULATIONS...ANOTHER WHICH BRINGS IN MORE WARM AIR AND AFFECTS US
WITH ANOTHER RAIN/SNOW MIX EVENT WITH LESSER ACCUMULATIONS. IN
GENERAL PREFER THE MORE CONSISTENT AND BETTER VERIFYING ECMWF WHICH
HAS THE LARGER SNOW ACCUMULATIONS...BUT CANNOT TOTALLY DISCOUNT THE
WARMER GFS EITHER. WE WILL HAVE TO WATCH THIS STORM VERY CAREFULLY
OVER THE NEXT SEVERAL DAYS TO MONITOR THESE TRENDS. YOU WILL
DEFINITELY WANT TO KEEP UP WITH THE LATEST INFORMATION REGARDING
THIS WINTER STORM SYSTEM. FOR NOW THE LATEST FORECAST REFLECTS A
BLENDED APPROACH...AND WE WILL HAVE TO REFINE WITH LATER FORECASTS.
..LE..
&&
.AVIATION...
AN UPPER LEVEL DISTURBANCE AND SOUTHWARD MOVING SURFACE COLD FRONT
WILL COMBINE TO PRODUCE SNOW SHOWERS OVER EASTERN IA INTO NW IL
THIS AFTERNOON AND EVENING. THIS WILL CAUSE CIGS TO LOWER TO
MVFR THIS EVENING. SNOW SHOWERS AND POSSIBLE IFR VISIBILITIES NOW
APPEAR MOST LIKELY TO AFFECT THE CID AND MLI TERMINALS...MAINLY IN
A WINDOW BETWEEN 22Z AND 03Z THIS EVENING. WEST TO NW WINDS FROM
14 TO 24 KTS WILL DIMINISH AND VEER TO MORE PREDOMINANTLY
NORTHWEST DURING THIS TIME. OVERNIGHT...AT LEAST PARTIAL CLEARING OF
CLOUDS IS EXPECTED WITH CONDITIONS IMPROVING TO VFR. AN UNSETTLED
PATTERN WILL CONTINUE INTO FRIDAY...WITH PREVAILING VFR CONDITIONS
EXPECTED WITH POSSIBLE FLURRIES THROUGH THE DAY.
SHEETS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SHEETS/LE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
310 PM CST THU FEB 14 2013
.SHORT TERM /TONIGHT/...
FORECAST CONCERN IS FOCUSED ON QUICK MOVING SHORTWAVE TO BRING SOME
LIGHT PRECIP TO THE FORECAST AREA THROUGH THIS EVENING. WEAK BROAD
FORCING ALONG THE COLD FRONT WILL BRING LIGHT SNOW OR RAIN THROUGH
THE LATE AFTERNOON BEFORE SWITCHING OVER TO ALL SNOW AFTER 00Z
FRIDAY. BUFR SOUNDINGS SHOWING BRIEF WINDOW OF FAIRLY DEEP
SATURATION FROM 21Z OR CURRENTLY THROUGH 03Z FRIDAY. COLUMN LOSES
ICE INTRODUCTION AND FORCING ACROSS NORTHERN IOWA B/T 00-03Z.
BELIEVE MODELS ARE BIT SLOW WITH MOVING THIS SYSTEM OUT AND CUT BACK
ON POPS PAST 03Z. 17Z HRRR QUICKLY DIMINISHES PRECIP BY 02Z WHICH
COINCIDES WITH SEVERAL OF THE HIRES WRF MODELS AND NAM12. ALSO
DECREASED SNOW AMOUNTS WITH THE QUICKER MOVEMENT...WEAKER FORCING
AND LESS MOISTURE AVAILABLE.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
COLD AIR SETTLING INTO THE REGION BY 12Z FRIDAY WITH GENERALLY A
CLOUDY DAY IN STORE. LINGERING FLURRIES WILL BE POSSIBLE FRIDAY WITH
WEAK WAVE PASSING THROUGH THE REGION DURING THE DAYTIME HOURS.
OTHERWISE TEMPERATURES WILL CREEP BACK UP DURING THE DAY TO NEAR 20
NORTH AND THE LOWER 30S IN THE SOUTH. AS HIGH BUILDS SOUTH FRIDAY
NIGHT SKIES WILL CLEAR OUT AND COLDER NIGHT IN STORE. LOWS WILL DROP
OFF INTO THE SINGLE DIGITS NORTH WITH THE TEENS IN THE SOUTHEAST.
H850 TEMPS REMAIN RATHER COLD THROUGH THE EARLY PART OF THE FORECAST
BUT AS THE RIDGE AXIS SLIPS EAST SATURDAY EVENING...TEMPS WARM
OVERNIGHT INTO SUNDAY MORNING. WARM AIR ADVECTION WILL INITIATE
CLOUDS WITH GENERALLY LIGHT FLOW OVERNIGHT. BY SUNDAY MED RANGE
MODELS CONTINUE WITH PREVIOUS RUNS TO SHOW DECENT WARM UP BY LATE
DAY. H850 TEMPS WARM TO NEAR 0C NORTHEAST AND TO NEAR 4-5C SOUTHWEST
AND WEST BY 00Z. THIS BODES WELL FOR TRENDS OF HIGHS IN THE 50S
ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA WITH HIGHS ABOVE
THE FREEZING MARK IN THE NORTHEAST. AS THE NEXT UPSTREAM WAVE
APPROACHES THE AREA ANOTHER STRONG COLD FRONT WILL PASS SOUTHEAST
THROUGH IOWA ON MONDAY. LIFT ASSOCIATED WITH IT WILL ALLOW FOR A
RAIN OR RAIN/SNOW MIXTURE TO OCCUR SOUTHEAST BY LATE IN THE
AFTERNOON. ANOTHER STRETCH OF COLDER THAN NORMAL WEATHER IS
ANTICIPATED FOR THE EARLY PORTION OF NEXT WEEK WITH A SLOW
MODERATION TOWARD THURSDAY...BUT STILL BELOW THE FREEZING MARK. MED
RANGE MODELS STILL PAINT AN ACTIVE STORM OVER THE FORECAST AREA BY
LATE WED OR EARLY THURSDAY WITH THE MAIN PORTION OF THE STORM TO HIT
THURSDAY THROUGH FRIDAY. SIGNATURE HAS SHOWN UP FOR TWO DAYS NOW IN
MOST MED RANGE MODELS...BUT EVEN SO...AT SEVEN DAYS OUT THERE ARE
STILL TO BE MANY CHANGES IN THE TRACK AND DETAILS. AT THIS TIME WILL
EMPHASIZE ONLY A STRONGER SYSTEM OVER THE CENTRAL STATES LOOKS MORE
LIKELY BUT WAY TOO EARLY TO BECOME OVERLY EXCITED ABOUT MODEL
DETAILS...ESPECIALLY GIVEN THAT THE 12Z GFS IS ABOUT 10 MB STRONGER
THAN THE 12Z EURO MODEL TODAY.
&&
.AVIATION...14/18Z
INTERMITTENT MVFR STRATUS WILL PERSIST THROUGH THE AFTERNOON AND LOW
CONFIDENCE WITH AN EXTENDED PERIOD OF MVFR STRATUS...BUT HIGH ENOUGH
TO MENTION TIMING WITH A TEMPO. COLD FRONT DRAPED ACROSS NORTHERN
IOWA WILL CONTINUE TO PUSH SOUTHWARD THROUGH THE AFTERNOON HOURS AND
LOOKS TO HAVE A LITTLE THICKER STRATUS BEHIND IT. LATEST HRRR HAS
CIGS FILLING BACK INTO CENTRAL IOWA PAST 20Z THIS AFTERNOON. OTHER
CONCERN IS WITH MVFR/IFR VIS DUE TO LIGHT SNOW DEVELOPING LATER THIS
AFTERNOON ALONG AND BEHIND THE FRONT. HAVE MENTION LOWER VIS AT
MCW/FOD/ALO THIS AFTERNOON. MAY SEE LOWER VIS AT DSM/OTM BY THE
EARLY EVENING BUT HAD LOW CONFIDENCE WITH MENTION AS NOT EXPECTING
TO BE PERSISTENT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...REV
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1143 AM CST THU FEB 14 2013
....UPDATED FOR 18Z AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
FIRST SHORTWAVE IS CURRENTLY SKIRTING THE NORTHEAST CORNER OF THE
STATE THIS MORNING WITH FIRST PUSH OF SLIGHTLY COOLER AIR INTO THE
STATE. HOWEVER...A SECOND SHORTWAVE WILL DROP SOUTHEAST THROUGH THE
DAKOTAS AND INTO THE STATE BY THIS AFTERNOON. WEAK TO MODERATE
FRONTOGENESIS WILL DROP INTO NORTH CENTRAL IOWA THIS AFTERNOON
ASSOCIATED WITH THIS WAVE ALONG WITH WEAK ISENTROPIC LIFT. FAIRLY
DEEP SATURATION AS WELL INDICATED IN THE BUFR SOUNDINGS AND LIGHT
SNOW IS EXPECTED IN THE NORTH DURING THE AFTERNOON. FARTHER
SOUTH...SOUNDINGS ARE WARMER AND IT APPEARS SOME THREAT OF RAIN AND
SNOW EXISTS AND HAVE MAINTAINED SOME MIX WITH INITIAL ONSET OF ANY
PCPN. SOUNDINGS MIX NICELY IN THE LOW LEVELS TODAY AND TEMPERATURES
SHOULD WARM BEFORE THE BIGGER PUSH OF COLD AIR ARRIVES LATE TODAY
INTO TONIGHT. AT THIS POINT...SNOW TOTALS IN THE NORTH WILL LIKELY
BE AROUND AN INCH.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
INITIALLY NORTHWEST TO NORTHERLY FLOW ALOFT REMAINS ACROSS THE
REGION...WITH A WEAK SHORTWAVE SLIDING SOUTHEASTWARD THROUGH THE
STATE TONIGHT. THIS WILL USHER IN ANOTHER PUSH OF COLD AIR...AND
PROVIDE SUPPORT FOR SOME LIGHT SNOW ACROSS MUCH OF THE CWA THIS
EVENING. EXPECT A BAND OF SNOW TO BE ORIENTED IN VICINITY OF THE HWY
20 CORRIDOR BY EARLY EVENING...WITH THE BAND MOVING OUT OF THE
SOUTHERN CWA BY THE EARLY MORNING HOURS. ANY ACCUMULATIONS SHOULD
REMAIN LIGHT WITH MOST SITES AROUND A HALF INCH OR LESS...WITH A FEW
LOCATIONS POSSIBLY RECEIVING AS MUCH AS AN INCH. WITH THE CONTINUED
PUSH OF COLD AIR INTO THE STATE...AND CYCLONIC FLOW ALOFT SCATTERED
FLURRIES EXPECTED TONIGHT THROUGH FRIDAY NIGHT. ANOTHER WEAK IMPULSE
ALSO SET TO DROP THROUGH THE CWA FRIDAY AFTERNOON. SOUNDINGS SHOWING
LITTLE MOISTURE THOUGH...SO HAVE JUST STUCK WITH THE FLURRY MENTION
WITH THIS WAVE. UPPER TROUGH TO FINALLY PUSH EAST OF THE REGION THIS
WEEKEND...WITH UPPER LEVEL RIDGING BUILDING INTO THE CENTRAL US
SATURDAY INTO SUNDAY.
RETURN FLOW WILL SETUP ACROSS THE REGION LATE SATURDAY NIGHT INTO
SUNDAY...WITH STRONG PUSH OF WAA SENDING H85 TEMPS INTO THE +4C
RANGE. WITH SOUTH TO SOUTHWEST FLOW AT THE SURFACE AND ALOFT AND
WITH MOSTLY SUNNY SKIES...SHOULD WARM UP NICELY SUNDAY. THEREFORE
CONTINUED TO GO ABOVE GUIDANCE FOR TEMPS SUNDAY....PUSHING TEMPS
INTO THE 40S/AROUND 50 ACROSS THE SOUTHWESTERN HALF OF THE CWA. AN
UPPER LEVEL WAVE THEN DIGS INTO THE NORTHERN US...SLIDING THROUGH
THE REGION BY MONDAY INTO MONDAY NIGHT. THE ASSOCIATED COLD FRONT
WILL SWEEP ACROSS THE CWA MONDAY...WITH A CHANCE FOR SOME LIGHT RAIN
EXPECTED TO DEVELOP IN VICINITY OF THE FRONT ACROSS THE SOUTHEASTERN
CWA MONDAY. OTHERWISE REMAINDER OF CWA SHOULD REMAIN DRY...AS DEF
ZONE PRECIP SHOULD SKIRT THE CWA TO THE NORTH/EAST. COULD SEE SOME
FLURRIES ACROSS THE FAR NORTH...BUT FOR NOW HAVE LEFT DRY. OTHERWISE
COLD AIR REMAINS IN PLACE THROUGH MUCH OF THE EXTENDED WITH HIGH
PRESSURE AND DRY CONDITIONS EXPECTED FOR TUESDAY INTO EARLY
WEDNESDAY.
LONG RANGE MODELS STILL IN VERY GOOD AGREEMENT DIGGING A DEEP UPPER
LEVEL TROUGH OVER THE INTERMOUNTAIN WEST BY MID WEEK...WITH THIS
SYSTEM EXPECTED TO EJECT EASTWARD THROUGH THE REGION JUST BEYOND THE
CURRENT FORECAST PERIOD TOWARD THURSDAY INTO FRIDAY. WITH MANY
DETAILS REMAINING UNCERTAIN THIS FAR OUT...STILL LOOKS LIKE AN
INCREASING LIKELIHOOD THAT A LARGE STORM SYSTEM COULD IMPACT THE
AREA BY THE END OF NEXT WEEK.
&&
.AVIATION...14/18Z
INTERMITTENT MVFR STRATUS WILL PERSIST THROUGH THE AFTERNOON AND LOW
CONFIDENCE WITH AN EXTENDED PERIOD OF MVFR STRATUS...BUT HIGH ENOUGH
TO MENTION TIMING WITH A TEMPO. COLD FRONT DRAPED ACROSS NORTHERN
IOWA WILL CONTINUE TO PUSH SOUTHWARD THROUGH THE AFTERNOON HOURS AND
LOOKS TO HAVE A LITTLE THICKER STRATUS BEHIND IT. LATEST HRRR HAS
CIGS FILLING BACK INTO CENTRAL IOWA PAST 20Z THIS AFTERNOON. OTHER
CONCERN IS WITH MVFR/IFR VIS DUE TO LIGHT SNOW DEVELOPING LATER THIS
AFTERNOON ALONG AND BEHIND THE FRONT. HAVE MENTION LOWER VIS AT
MCW/FOD/ALO THIS AFTERNOON. MAY SEE LOWER VIS AT DSM/OTM BY THE
EARLY EVENING BUT HAD LOW CONFIDENCE WITH MENTION AS NOT EXPECTING
TO BE PERSISTENT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...COGIL
LONG TERM...BEERENDS
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
531 PM CST FRI FEB 15 2013
...UPDATE TO AVIATION...
.DISCUSSION...
12Z UPPER AIR DATA DEPICTED AT 130KT JET DIVING SOUTH OUT OF WESTERN
SASKATCHEWAN WITH WIDESPREAD 500MB TEMPS OF AROUND -40C OVER THE
NORTHERN PLAINS AND EASTERN CANADA. AN UPPER LEVEL TROF WAS MAKING
SOUTHWARD PROGRESS OUT OF THE WESTERN DAKOTAS IN RECENT HOURS PER
WATER VAPOR IMAGERY. WEAK RADAR RETURNS HAVE DEVELOPED OVER MUCH OF
NORTHERN KANSAS THOUGH DEWPOINT DEPRESSIONS AROUND 20F ARE LIKELY
KEEP MUCH OF THIS WEAK ACTIVITY FROM REACHING THE GROUND. 20Z
SURFACE-3KM LAPSE RATES NEAR 9C/KM WERE NOTED IN CENTRAL
NEBRASKA...WITH AROUND 8C/KM VALUES EAST AND ALSO SOUTHEAST INTO THE
LOCAL AREA.
THE MAIN ISSUES TONIGHT ARE WHERE AND HOW LONG THE SNOW SHOWERS WILL
LAST. THE VARIOUS GUIDANCE ALL POINTS TO A MORE SUSTAINED AREA OF
PRECIPITATION SOMEWHERE IN NORTHEAST KANSAS...WITH THE DETAILS THE
MAIN ISSUE. AS THE UPPER TROF CONTINUES SOUTH TO SOUTHEAST...THE
LAPSE RATES REMAIN NEAR 8C/KM WELL INTO THE NIGHT AS FRONTOGENESIS
AROUND 750MB INCREASES AND FOCUSES ON THE NORTHEAST TIP OF A
DEVELOPING THETA-E RIDGE AT THIS LEVEL...RESULTING IN GOOD LIFT
THROUGH THE DENDRITIC GROWTH ZONE. THE MOST RECENT HRRR AND RAP DATA
HAS BEEN PUSHING THIS AREA NORTHEAST...FAVORING FAR NORTHEAST KANSAS
MAINLY AROUND 03Z. HAVE INCREASED CHANCES AND AMOUNTS UP HERE...BUT
STILL LIMITED MOISTURE AND THE COVERAGE OF ANY BANDS AND EXACTLY
WHERE THIS WILL END UP KEEPS CHANCES BELOW LIKELY LEVELS. SOME BRIEF
MODERATE SNOWFALLS CAN BE EXPECTED IN THE HEAVIEST PRECIPITATION...
AND LOCAL AMOUNTS NEAR AN INCH SEEM PLAUSIBLE. ANY ACCUMULATING SNOW
SHOULD END WELL BEFORE SUNRISE AS THE UPPER TROF SWINGS INTO THE
MISSISSIPPI VALLEY. WESTERN AREAS SEE A QUICKLY DRYING TROPOSPHERE
THIS EVENING...BUT HIGH CLOUD RETURNS THERE LATE TONIGHT AS WARM AIR
ADVECTION ENSUES FROM THE UPPER PATTERN SHIFTING EAST. THOUGH
INSOLATION WILL BE LIMITED AS THE CLOUDS DEEPEN SATURDAY...SOUTHWEST
WINDS SHOULD SUPPORT TEMPS SEVERAL DEGREES ABOVE TODAYS LEVELS FOR
CENTRAL AND WESTERN LOCATIONS.
65
SHORTWAVE RIDGING AND WARM AIR ADVECTION IS EXPECTED TO BRING WARMER
TEMPS AND SUNNY SKIES TO THE AREA FOR SUNDAY. THEN THE NEXT
SHORTWAVE IS EXPECTED TO MOVE ACROSS THE CENTRAL AND NORTHERN PLAINS
BRINGING A COLD FRONT THROUGH THE AREA LATE SUNDAY NIGHT AND MONDAY
MORNING. MODELS CONTINUE TO SHOW THE BETTER MOISTURE TO THE EAST OF
THE FORECAST AREA. AND WITH THE FRONT PUSHING INTO MO BY THE LATE
MORNING HOURS...PRECIP CHANCES SHOULD BE CONFINED TO FAR EASTERN KS
DURING THE DAY MONDAY.
TUESDAY AND WEDNESDAY LOOK TO BE IN BETWEEN SYSTEMS WITH SURFACE
RIDGING BUILDING SOUTH THROUGH THE PLAINS. THIS SHOULD KEEP TEMPS
FROM WARMING UP VERY MUCH. THE NEXT BIG WEATHER MAKER LOOKS TO
IMPACT THE REGION WEDNESDAY NIGHT AND THURSDAY. BOTH THE GFS AND
ECMWF HAVE TRENDED SLIGHTLY SLOWER WITH THE UPPER CLOSED LOW AS IT
MOVES OUT OF THE SOUTHERN ROCKIES. HOWEVER THE GFS REMAINS SLIGHTLY
FASTER THAN THE GFS. THE OTHER TREND OF NOTE IS THE ECMWF FURTHER
NORTH WITH THE TRACK OF THE LOW PRESSURE SYSTEM. THIS COMPLICATES
THE FORECAST OF PRECIP TYPE QUITE A BIT. INITIALLY WITH THE COLD
SURFACE RIDGE IN PLACE WEDNESDAY...GFS FORECAST SOUNDINGS SUPPORT
ALL SNOW WEDNESDAY EVENING. HOWEVER BOTH MODELS SHOW STRONG WARM AIR
ADVECTION ALOFT AND A WARM NOSE DEVELOPING THROUGH THE NIGHT WITH
SURFACE TEMPS REMAINING IN THE 20S AND LOWER 30S. AS THE WARM AIR
ADVECTION DEVELOPS...FREEZING RAIN AND SLEET BECOME POSSIBLE WHILE
SURFACE TEMPS ARE BELOW FREEZING. ON TOP OF THIS IS THE POTENTIAL
FOR MID LEVEL DRY AIR TO WRAP UP IN THE SYSTEM AND FOR THE SOUNDINGS
TO LOOSE SATURATION WITHIN THE DENDRITIC GROWTH LAYER ADDING TO THE
POTENTIAL FOR FREEZING RAIN. REALLY THE TRACK OF THE SYSTEM DOES NOT
FAVOR AN ALL SNOW EVENT FOR THE BULK OF THE FORECAST AREA.
CONFIDENCE IN TRYING TO NAIL DOWN PRECIP TYPE IS VERY LOW AT THIS
POINT GIVEN THAT IT IS 6 DAYS OUT...BUT THINK THAT THE PROBABILITY
OF MIX WINTRY PRECIP IS HIGH ENOUGH THAT IT SHOULD BE MENTIONED IN
THE FORECAST. ONE SHOULD NOT GET CAUGHT UP ON WHERE THE FORECAST HAS
THE RAIN/SNOW LINE /WHICH IS LIKELY TO FLUCTUATE IN THE COMING
DAYS/...BUT THAT THERE IS THE POTENTIAL FOR A MIXED BAG OF PRECIP.
THINGS THAT COULD CHANGE THIS IS IF THE MAGNITUDE OF LOW LEVEL WARM
AIR ADVECTION WERE TO INCREASE AND RAISE SURFACE TEMPS ABOVE
FREEZING OR IF THE STORM SYSTEM TRENDS SOUTH AGAIN. IN ANY CASE IT
LOOKS TO BE MESSY.
WOLTERS
&&
.AVIATION...
EXPECT OCCASIONAL FLURRIES OVERNIGHT WITH SCATTERED SNOW SHOWERS
THROUGH 6Z. THE HEAVIER SNOW SHOWERS MAY REDUCE VISIBILITIES DOWN
TO 2 TO 3 SM AND CEILINGS MAY BRIEFLY DROP TO MVFR. AFTER 8Z THE
SNOW SHOWERS AND FLURRIES WILL PUSH SOUTHEAST OF THE TAF SITES AND
CEILINGS AND VISIBILITIES WILL REMAIN ABOVE VFR.
GARGAN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS JACKSON KY
1250 AM EST THU FEB 14 2013
.UPDATE...
ISSUED AT 1250 AM EST THU FEB 14 2013
UPDATED THE FORECAST TO ADJUST THE CLOUD COVER FOR SOME ANTICIPATED
LOW LEVEL STRATO CU. COVERAGE SHOULD SLOWLY SPREAD SPREAD WEST
THROUGH THE NIGHT NIGHT BEFORE LIFTING AFTER 12Z. OTHERWISE THE
FORECAST IS ON TRACK.
UPDATE ISSUED AT 1006 PM EST WED FEB 13 2013
PRECIP SHOULD BE DONE FOR THE NIGHT AND IS REMOVED FROM THE 1ST
PERIOD FORECAST. CLOUDS WILL BE TRICKY...BUT SHOULD GENERALLY BE MOST
PREVALENT IN THE SE AND LEAST IN THE NW OVERNIGHT.
UPDATE ISSUED AT 655 PM EST WED FEB 13 2013
HAVE UPDATED PRIMARILY FOR SKY COVER AND POPS IN THE FIRST PERIOD.
CLEARING WAS ARRIVING FROM THE WEST EARLY THIS EVENING...AND BASED ON
THE RUC AND NAM SHOULD PROGRESS SOUTHEAST TONIGHT. HOWEVER...THEY DO
ALSO SUGGEST ANOTHER INCREASE IN CLOUDS FROM THE WEST BEFORE DAWN.
THE ONLY RETURNS LEFT ON RADAR WERE IN THE FAR EASTERN PART OF THE
AREA...WERE VERY LIGHT AND ON THE DECREASE. HAVE LOWERED POPS TO
NOTHING MORE THAN 20 PERCENT OVER THE EASTERN TIP OF THE AREA...BUT
DID ALLOW FOR SOME FLURRIES A BIT FURTHER WEST.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 231 PM EST WED FEB 13 2013
THE SFC LOW HAS PUSHED EAST INTO VA AND A SHORT PERIOD OF COLDER AIR
IS CYCLING INTO THE AREA ON NW WINDS. MID LEVEL TROF RUNS FROM NEAR
CLE TO CMH TO BNA AND WILL FOLLOW TO THE EAST LATER THIS AFTERNOON.
WITH THE PASSAGE OF THE MID LEVEL TROF THIS EVENING THE PCPN SHOULD
COME TO AN END AND RIDGING AT BOTH THE SFC AND MID LEVELS WILL BUILD
INTO THE AREA. EXPECTING TEMPS TO FALL SLOWLY THE REST OF THIS
AFTERNOON AND OVERNIGHT. CURRENT TEMPS IN THE MID 30S WILL BOTTOM OUT
IN THE MORNING NEAR 30. THEN THE RIDGING WILL BRING A RETURN TO MLDER
TEMPS THU AFTERNOON WITH HIGHS CLIMBING TO THE LOWER 50S. THE NEXT
DISTURBANCE...CURRENTLY IN THE NRN PLAINS...WILL PUSH ACROSS THE WRN
GREAT LAKES THU NIGHT BUT NOT IN TIME TO BRING MUCH COLDER TEMPS AS
THE WINDS WILL SLOWLY RETURN TO THE WEST AND THEN SW TOWARDS FRI DAWN
SO TEMPS WILL ONLY DROP TO THE LOWER 30S THU NIGHT...BUT UNDER PARTLY
CLOUDY SKIES AND WITHOUT ANY PCPN.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 315 PM EST WED FEB 13 2013
A FAIRLY ACTIVE AND PROGRESSIVE WEATHER PATTERN WILL BE IN PLACE
DURING THE LONG TERM PORTION OF THE FORECAST. A SERIES OF
DISTURBANCES WILL CARVE OUT A DEEP TROF OVER THE EASTERN UNITED
STATES FOR THE UPCOMING WEEKEND. AS COLDER AIR MOVES INTO THE AREA ON
FRIDAY...MAY SEE SOME RAIN OR SNOW SHOWERS. WITH COLD AIR ADVECTION
AND SOME UPSLOPE FLOW SNOW SHOWERS WILL ALSO BE POSSIBLE AT TIMES
FROM FRIDAY NIGHT INTO SATURDAY NIGHT...MAINLY IN THE EASTERN PART OF
THE FORECAST AREA.
THE UPPER LEVEL TROF WILL QUICKLY MOVE EAST WITH WEAK RIDGING OVER
THE OH VALLEY BY MONDAY. THIS WILL RESULT IN A QUICK WARM UP WITH
TEMPERATURES RETURNING TO ABOVE NORMAL READINGS ON MONDAY AFTER WELL
BELOW NORMAL TEMPERATURES OVER THE WEEKEND. AN APPROACHING COLD FRONT
WILL BRING ANOTHER ROUND OF RAIN SHOWERS MONDAY NIGHT INTO
TUESDAY. THERE COULD BE SOME LIGHT SNOW SHOWERS TUESDAY NIGHT AS
COLDER AIR RETURNS ONCE AGAIN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1250 AM EST THU FEB 14 2013
THE MAIN CONCERN FOR THE FIRST 6 HOURS OF THE TAF PERIOD IS SOME LOW
LEVEL STRATO CU THAT IS EXPECTED TO DEVELOP OVER THE SOUTH AND
EASTERN KENTUCKY. THE MVFR AND IFR CEILINGS WILL LIFT TO ABOUT 5 KFT
AFTER 12Z. DURING THE DAY...WINDS UP TO 20 KNOTS OUT OF THE NORTHWEST
WILL MIX TO THE SURFACE BEFORE TAPERING OFF BY 23Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SHALLENBERGER
SHORT TERM...DUSTY
LONG TERM...SBH
AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION...UPDATED
NWS WAKEFIELD VA
434 PM EST THU FEB 14 2013
.SYNOPSIS...
HIGH PRESSURE SLIDES OFF THE COAST TONIGHT AND A COLD FRONT
APPROACHES THE MID ATLANTIC REGION ON FRIDAY. THE COLD FRONT
WILL PASS THROUGH THE AREA FRIDAY NIGHT...FOLLOWED BY UNSETTLED
CONDITIONS AND A COOLER CANADIAN AIRMASS FOR THE REMAINDER OF THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
HIGH PRESSURE SLIDES OFF THE COAST TONIGHT. AS THIS HAPPENS...A
STEADY STREAM OF MID TO HIGH LEVEL CLOUDS OVER SE VA AND NE NC WILL
GRADUALLY MOVE EWD WITH THE BACK EDGE OF THE RIDGE. EXPECT MOSTLY
CLEAR SKIES AREAWIDE TONIGHT WITH LOWS IN THE 30S (NEAR 40 IMMEDIATE
COAST).
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
FRIDAY AND FRIDAY NIGHT...
FRIDAY WILL BE A DAY OF TRANSITION WITH HIGH PRESSURE OFF THE
COAST AND A COLD FRONT APPROACHING FROM THE WEST. THE DAY WILL
START OFF MOSTLY SUNNY BUT HIGH CLOUDS WILL MOVE INTO THE AREA
FROM THE NORTHWEST DURING THE AFTN. THE COLD FRONT...WHICH EXTENDS
FROM A LOW PRESSURE SYSTEM TRACKING ACROSS THE ST LAWRENCE RIVER
VALLEY...WILL PASS THROUGH THE AREA FRIDAY NIGHT. PRECIP BEGINS AS
ALL RAIN AND IS EXPECTED TO CHANGE OVER TO SNOW OR A RAIN/SNOW MIX
AFTER MIDNIGHT AS COLD AIR INFILTRATES THE WRN HALF OF THE FA.
EXPECT SNOW OVER FAR NW AREAS...AND A RAIN/SNOW MIX GENERALLY
ALONG THE I-95 TRAVEL CORRIDOR BY EARLY SATURDAY MORNING.
SATURDAY AND SATURDAY NIGHT...
AN AREA OF LOW PRESSURE IS NOW PROGGED TO DEVELOP OFF THE NC COAST
EARLY SATURDAY AND STAY JUST OFF THE MID ATLANTIC COAST DURING THE
DAY. MEANWHILE SHORTWAVE ENERGY ROUNDING THE BASE OF THE DEEP
UPPER LEVEL TROUGH...A STRONG JET STREAK MAXING OUT AROUND 150 KT...
AND PLENTY OF COLD CANADIAN AIR ON THE BACK SIDE OF THE LOW WILL
MAKE FOR AN INTERESTING FORECAST. THE NAM AND GFS MODELS ARE IN
FAIR AGREEMENT WITH THE PLACEMENT OF THE DEVELOPING LOW PRESSURE
CENTER (NAM IS A BIT FURTHER TO THE EAST BUT NOT BY MUCH) AND ALSO
WITH GENERAL PLACEMENT OF QPF. THE GFS IS BULLISH WITH THE 6HR
PRECIP AMTS AND THE NAM APPEARS TO BE TOO LIMITED WITH ITS QPF
COVERAGE/AMTS DUE TO ITS CONVECTIVE PARAMETERIZATIONS. HIGHER QPF
AMOUNTS ARE ANTICIPATED TO OCCUR GENERALLY ALONG AND NORTH OF I-64
INCLUDING THE MD/VA EASTERN SHORE. ALSO...A VERY TIGHT PRESSURE
GRADIENT DEVELOPS DUE TO COLD AND DRY CANADIAN AIR TO THE
NORTHWEST AND WARM/MOIST AIR TO THE SOUTHEAST. NORTHWEST WINDS
WILL BECOME BREEZY...ESPECIALLY ALONG THE COAST.
THE CLASH OF AIRMASSES SHOULD KEEP PERSISTENT WINTRY PRECIP OVER
FAR NW AREAS THROUGH MOST OF THE DAY SATURDAY. HAVE INTRODUCED A
COMBO OF SNOW AND SLEET (REALLY GRAUPEL AKA SNOW GRAINS) DURING
THE DAY AS THE UPPER LEVEL TROUGH ENHANCES CONVECTIVE PRECIP AND
WILL HELP DRIVE DOWN SNOW LEVELS AND WET BULB ZERO HEIGHTS. BY
LATE AFTN/EARLY SATURDAY EVENING...WINTRY PRECIP IS EXPECTED TO
SHIFT FURTHER TO THE SOUTHEAST AS A SNOW/GRAUPEL MIX WITH RAIN
NEAR THE IMMEDIATE COAST. AS THE COASTAL LOW TRACKS TO THE
NORTHEAST DURING THE EVENING AND TEMPERATURES BEGIN TO DROP...
PRECIP SHOULD BECOME ALL SNOW BY LATE EVENING. STORM TOTAL SNOW
ACCUMULATIONS AT THIS TIME RANGE FROM 0.6-1.6 INCHES NORTH OF A
LINE FROM FVX-RIC-SBY...AND 0.5 INCHES OR LESS SOUTH OF THIS LINE.
THE POTENTIAL FOR WINTRY CONDITIONS WILL BE COVERED IN THE
HAZARDOUS WEATHER OUTLOOK AT THIS TIME.
PRECIP IS EXPECTED TO QUICKLY SHUT OFF LATE SATURDAY EVENING ONCE
THE LOW MOVES AWAY FROM THE MID ATLANTIC COAST. COLDER AIR WILL BE
ABLE TO TAKE HOLD OF THE REGION SATURDAY NIGHT DESPITE DECENT
MIXING PROVIDED BY NORTHWEST REMAINING ELEVATED OVERNIGHT.
ANTICIPATE LOWS IN THE 20S. THE REGION WILL STAY UNDER THE
INFLUENCE OF A BROAD UPPER LEVEL TROUGH THROUGH SUNDAY. COLDER AIR
AND BREEZY WNW WINDS SHOULD PRODUCE WIND CHILLS IN THE UPPER TEENS
TO LOWER 20S SUNDAY MORNING. EXPECT COOL HIGHS WITH TEMPS IN THE
MID TO UPPER 30S (NEAR 40 IMMEDIATE COAST).
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
WILL LEAN TOWARD HPC GUIDANCE. THIS LEANS TOWARD A ECMWF ENSEMBLE
SOLUTION. AFTER THE COLD FRONT AND LOW MOVE AWAY SUNDAY SHOULD BE
A SUNNY COLD BREEZY DAY WITH TEMPERATURES BELOW NORMAL. IT SHOULD
CONTINUE DRY THROUGH MONDAY WITH JUST A SLIGHT WARM UP ON MONDAY.
THE FIRST SYSTEM TO IMPACT THE AREA WILL BE ON TUESDAY. BOTH GFS
AND ECMWF ARE SIMILAR WITH THE MAIN LOW GOING UP TO THE WEST OF
THE AREA AND PLENTY OF WARM AIR ARRIVING AHEAD OF THE PRECIPITATION
SO WENT WITH MAINLY A RAIN EVENT. THE FRONT WILL AGAIN PUSH THROUGH
ON TUESDAY NIGHT WITH PLENTY OF COLD AIR AND THERE COULD BE SOME
MIX OR CHANGE TO SNOW SHOWERS AS THE FRONT PASSES. THE NEXT SYSTEM
APPROACHES TOWARD THE END OF THE PERIOD. THE MODELS CONSENSUS
WOULD KEEP IT MAINLY OUT OF THE AREA UNTIL FRIDAY SO KEPT IT DRY
THROUGH THURSDAY. FOLLOWED ALONG CLOSE TO MOSGUIDE TEMPERATURES
WHICH WERE ALSO CLOSE TO HPC. THIS KEEPS TEMPERATURES BELOW NORMAL
FOR WEDNESDAY AND THURSDAY.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
LOOKING AT RAP SOUNDINGS CAN SEE ENOUGH MOISTURE IN THE BOUNDARY
LAYER FOR SOME CLOUDS AND HAVE SEEN ESPECIALLY TOWARD THE COAST A
BKN LAYER CLOSE TO 3000 FEET. THIS WILL SLOWLY LIFT AND DISSIPATE
AS THE AFTERNOON GOES ON WITH MAINLY CLEAR SKIES BY EVENING. WINDS
WILL BE VARIABLE AND LIGHT. CONTINUED VFR CONDITIONS TONIGHT AND
FRIDAY.
A STRONG COLD FRONT MOVES THROUGH THE AREA LATE FRIDAY NIGHT/EARLY
SATURDAY MORNING. THERE IS A CHANCE OF RAIN AND/OR SNOW SHOWERS
WITH THE FRONTAL PASSAGE ESPECIALLY FROM NW OF A LINE FROM RIC TO
SBY AND THIS COULD LEAD TO MVFR OR IFR CONDITIONS FOR A TIME AS
INTO SATURDAY AFTERNOON BEFORE VFR BUT BREEZY CONDITIONS RETURN
FOR THE REST OF THE WEEKEND.
&&
.MARINE...
SFC HI PRES MOVES OVR THE WTRS FM THIS EVE THROUGH FRI MRNG. NEXT
CDFNT APPROACHES FM THE W FRI AFTN/EVE...AND SLOWS AT IT REACHES
THE CST SAT MRNG. MEANWHILE...WK SFC LO PRES BEGINS TO DVLP A FEW
HUNDRED MI OFF THE NC/SC CST SAT MRNG. 12Z/14 NAM/GFS BOTH
GRADUALLY INTENSIFY THE LO AS IT TRACKS NNE OFFSHR SAT INTO SAT
NGT...(THE GFS MORE SO THAN THE NAM...AS WELL AS BEING CLOSER TO
THE IMMEDIATE CST). CONTG W/ IDEA OF DELAY IN STRONGEST LO LVL CAA
UNTIL SAT EVE THROUGH SUN...AS A RESULT OF THE STRENGTHENING SFC
LO PRES TRACKING E OF CAPE COD...AND THE MID/UPR LVL TROUGH
CROSSES THE MDATLC RGN. INCRSG CONFIDENCE FOR SOLID SCAS FM LT SAT
THROUGH SUN...W/ (RIGHT NOW AT LEAST) A LO PROB FOR A PD OF
GALES...ESP ON THE NRN OCN WTRS. LO LVL CAA RMNS THROUGH SUN
NGT/ERY MON...BEFORE WANING DURG MON AS SFC HI PRES ARRIVES FM THE
W/TROUGH ALOFT DEPARTS THROUGH THE CANADIAN MARITIMES (RESULTING
IN LIGHTER WINDS/LWRG WAVES/SEAS).
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BMD
NEAR TERM...BMD
SHORT TERM...BMD
LONG TERM...JAB
AVIATION...AJZ/JAB
MARINE...ALB
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
423 PM EST THU FEB 14 2013
.SYNOPSIS...
HIGH PRESSURE SLIDES OFF THE COAST TONIGHT AND A COLD FRONT
APPROACHES THE MID ATLANTIC REGION ON FRIDAY. THE COLD FRONT
WILL PASS THROUGH THE AREA FRIDAY NIGHT...FOLLOWED BY UNSETTLED
CONDITIONS AND A COOLER CANADIAN AIRMASS FOR THE REMAINDER OF THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
HIGH PRESSURE SLIDES OFF THE COAST TONIGHT. AS THIS HAPPENS...A
STEADY STREAM OF MID TO HIGH LEVEL CLOUDS OVER SE VA AND NE NC WILL
GRADUALLY MOVE EWD WITH THE BACK EDGE OF THE RIDGE. EXPECT MOSTLY
CLEAR SKIES AREAWIDE TONIGHT WITH LOWS IN THE 30S (NEAR 40 IMMEDIATE
COAST).
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
FRIDAY AND FRIDAY NIGHT...
FRIDAY WILL BE A DAY OF TRANSITION WITH HIGH PRESSURE OFF THE
COAST AND A COLD FRONT APPROACHING FROM THE WEST. THE DAY WILL
START OFF MOSTLY SUNNY BUT HIGH CLOUDS WILL MOVE INTO THE AREA
FROM THE NORTHWEST DURING THE AFTN. THE COLD FRONT...WHICH EXTENDS
FROM A LOW PRESSURE SYSTEM TRACKING ACROSS THE ST LAWRENCE RIVER
VALLEY...WILL PASS THROUGH THE AREA FRIDAY NIGHT. PRECIP BEGINS AS
ALL RAIN AND IS EXPECTED TO CHANGE OVER TO SNOW OR A RAIN/SNOW MIX
AFTER MIDNIGHT AS COLD AIR INFILTRATES THE WRN HALF OF THE FA.
EXPECT SNOW OVER FAR NW AREAS...AND A RAIN/SNOW MIX GENERALLY
ALONG THE I-95 TRAVEL CORRIDOR BY EARLY SATURDAY MORNING.
SATURDAY AND SATURDAY NIGHT...
AN AREA OF LOW PRESSURE IS NOW PROGGED TO DEVELOP OFF THE NC COAST
EARLY SATURDAY AND STAY JUST OFF THE MID ATLANTIC COAST DURING THE
DAY. MEANWHILE SHORTWAVE ENERGY ROUNDING THE BASE OF THE DEEP
UPPER LEVEL TROUGH...A STRONG JET STREAK MAXING OUT AROUND 150 KT...
AND PLENTY OF COLD CANADIAN AIR ON THE BACK SIDE OF THE LOW WILL
MAKE FOR AN INTERESTING FORECAST. THE NAM AND GFS MODELS ARE IN
FAIR AGREEMENT WITH THE PLACEMENT OF THE DEVELOPING LOW PRESSURE
CENTER (NAM IS A BIT FURTHER TO THE EAST BUT NOT BY MUCH) AND ALSO
WITH GENERAL PLACEMENT OF QPF. THE GFS IS BULLISH WITH THE 6HR
PRECIP AMTS AND THE NAM APPEARS TO BE TOO LIMITED WITH ITS QPF
COVERAGE/AMTS DUE TO ITS CONVECTIVE PARAMETERIZATIONS. HIGHER QPF
AMOUNTS ARE ANTICIPATED TO OCCUR GENERALLY ALONG AND NORTH OF I-64
INCLUDING THE MD/VA EASTERN SHORE. ALSO...A VERY TIGHT PRESSURE
GRADIENT DEVELOPS DUE TO COLD AND DRY CANADIAN AIR TO THE
NORTHWEST AND WARM/MOIST AIR TO THE SOUTHEAST. NORTHWEST WINDS
WILL BECOME BREEZY...ESPECIALLY ALONG THE COAST.
THE CLASH OF AIRMASSES SHOULD KEEP PERSISTENT WINTRY PRECIP OVER
FAR NW AREAS THROUGH MOST OF THE DAY SATURDAY. HAVE INTRODUCED A
COMBO OF SNOW AND SLEET (REALLY GRAUPEL AKA SNOW GRAINS) DURING
THE DAY AS THE UPPER LEVEL TROUGH ENHANCES CONVECTIVE PRECIP AND
WILL HELP DRIVE DOWN SNOW LEVELS AND WET BULB ZERO HEIGHTS. BY
LATE AFTN/EARLY SATURDAY EVENING...WINTRY PRECIP IS EXPECTED TO
SHIFT FURTHER TO THE SOUTHEAST AS A SNOW/GRAUPEL MIX WITH RAIN
NEAR THE IMMEDIATE COAST. AS THE COASTAL LOW TRACKS TO THE
NORTHEAST DURING THE EVENING AND TEMPERATURES BEGIN TO DROP...
PRECIP SHOULD BECOME ALL SNOW BY LATE EVENING. STORM TOTAL SNOW
ACCUMULATIONS AT THIS TIME RANGE FROM 0.6-1.6 INCHES NORTH OF A
LINE FROM FVX-RIC-SBY...AND 0.5 INCHES OR LESS SOUTH OF THIS LINE.
PRECIP IS EXPECTED TO QUICKLY SHUT OFF LATE SATURDAY EVENING ONCE
THE LOW MOVES AWAY FROM THE MID ATLANTIC COAST. COLDER AIR WILL BE
ABLE TO TAKE HOLD OF THE REGION SATURDAY NIGHT DESPITE DECENT
MIXING PROVIDED BY NORTHWEST REMAINING ELEVATED OVERNIGHT.
ANTICIPATE LOWS IN THE 20S. THE REGION WILL STAY UNDER THE
INFLUENCE OF A BROAD UPPER LEVEL TROUGH THROUGH SUNDAY. COLDER AIR
AND BREEZY WNW WINDS SHOULD PRODUCE WIND CHILLS IN THE UPPER TEENS
TO LOWER 20S SUNDAY MORNING. EXPECT COOL HIGHS WITH TEMPS IN THE
MID TO UPPER 30S (NEAR 40 IMMEDIATE COAST).
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
WILL LEAN TOWARD HPC GUIDANCE. THIS LEANS TOWARD A ECMWF ENSEMBLE
SOLUTION. AFTER THE COLD FRONT AND LOW MOVE AWAY SUNDAY SHOULD BE
A SUNNY COLD BREEZY DAY WITH TEMPERATURES BELOW NORMAL. IT SHOULD
CONTINUE DRY THROUGH MONDAY WITH JUST A SLIGHT WARM UP ON MONDAY.
THE FIRST SYSTEM TO IMPACT THE AREA WILL BE ON TUESDAY. BOTH GFS
AND ECMWF ARE SIMILAR WITH THE MAIN LOW GOING UP TO THE WEST OF
THE AREA AND PLENTY OF WARM AIR ARRIVING AHEAD OF THE PRECIPITATION
SO WENT WITH MAINLY A RAIN EVENT. THE FRONT WILL AGAIN PUSH THROUGH
ON TUESDAY NIGHT WITH PLENTY OF COLD AIR AND THERE COULD BE SOME
MIX OR CHANGE TO SNOW SHOWERS AS THE FRONT PASSES. THE NEXT SYSTEM
APPROACHES TOWARD THE END OF THE PERIOD. THE MODELS CONSENSUS
WOULD KEEP IT MAINLY OUT OF THE AREA UNTIL FRIDAY SO KEPT IT DRY
THROUGH THURSDAY. FOLLOWED ALONG CLOSE TO MOSGUIDE TEMPERATURES
WHICH WERE ALSO CLOSE TO HPC. THIS KEEPS TEMPERATURES BELOW NORMAL
FOR WEDNESDAY AND THURSDAY.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
LOOKING AT RAP SOUNDINGS CAN SEE ENOUGH MOISTURE IN THE BOUNDARY
LAYER FOR SOME CLOUDS AND HAVE SEEN ESPECIALLY TOWARD THE COAST A
BKN LAYER CLOSE TO 3000 FEET. THIS WILL SLOWLY LIFT AND DISSIPATE
AS THE AFTERNOON GOES ON WITH MAINLY CLEAR SKIES BY EVENING. WINDS
WILL BE VARIABLE AND LIGHT. CONTINUED VFR CONDITIONS TONIGHT AND
FRIDAY.
A STRONG COLD FRONT MOVES THROUGH THE AREA LATE FRIDAY NIGHT/EARLY
SATURDAY MORNING. THERE IS A CHANCE OF RAIN AND/OR SNOW SHOWERS
WITH THE FRONTAL PASSAGE ESPECIALLY FROM NW OF A LINE FROM RIC TO
SBY AND THIS COULD LEAD TO MVFR OR IFR CONDITIONS FOR A TIME AS
INTO SATURDAY AFTERNOON BEFORE VFR BUT BREEZY CONDITIONS RETURN
FOR THE REST OF THE WEEKEND.
&&
.MARINE...
SFC HI PRES MOVES OVR THE WTRS FM THIS EVE THROUGH FRI MRNG. NEXT
CDFNT APPROACHES FM THE W FRI AFTN/EVE...AND SLOWS AT IT REACHES
THE CST SAT MRNG. MEANWHILE...WK SFC LO PRES BEGINS TO DVLP A FEW
HUNDRED MI OFF THE NC/SC CST SAT MRNG. 12Z/14 NAM/GFS BOTH
GRADUALLY INTENSIFY THE LO AS IT TRACKS NNE OFFSHR SAT INTO SAT
NGT...(THE GFS MORE SO THAN THE NAM...AS WELL AS BEING CLOSER TO
THE IMMEDIATE CST). CONTG W/ IDEA OF DELAY IN STRONGEST LO LVL CAA
UNTIL SAT EVE THROUGH SUN...AS A RESULT OF THE STRENGTHENING SFC
LO PRES TRACKING E OF CAPE COD...AND THE MID/UPR LVL TROUGH
CROSSES THE MDATLC RGN. INCRSG CONFIDENCE FOR SOLID SCAS FM LT SAT
THROUGH SUN...W/ (RIGHT NOW AT LEAST) A LO PROB FOR A PD OF
GALES...ESP ON THE NRN OCN WTRS. LO LVL CAA RMNS THROUGH SUN
NGT/ERY MON...BEFORE WANING DURG MON AS SFC HI PRES ARRIVES FM THE
W/TROUGH ALOFT DEPARTS THROUGH THE CANADIAN MARITIMES (RESULTING
IN LIGHTER WINDS/LWRG WAVES/SEAS).
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BMD
NEAR TERM...BMD
SHORT TERM...BMD
LONG TERM...JAB
AVIATION...AJZ/JAB
MARINE...ALB
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1247 PM EST THU FEB 14 2013
.SYNOPSIS...
HIGH PRESSURE RETURNS TODAY IN WAKE OF DEPARTING LOW PRESSURE. A
COLD FRONT PASSES THROUGH THE REGION LATE FRIDAY...FOLLOWED BY
UNSETTLED CONDITIONS AND A COOLER CANADIAN AIRMASS FOR THE REMAINDER
OF THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST WATER VAPOR IMAGERY SHOWS SEVERAL SHORTWAVES EMBEDDED IN
BROAD UPPER LEVEL TROUGH OVER THE CNTRL/ERN CONUS THIS MORNING.
SHORTWAVE/ENERGY RESPONSIBLE FOR PRECIP YESTERDAY HAS PUSHED OFF THE
NE COAST. ALSO VISIBLE IS SRN STREAM MOISTURE BEING SHUNTED TO THE
SOUTH OF THE REGION ALLOWING FOR DRYING CONDITIONS OVER THE MID
ATLANTIC. AT THE SFC...LOW PRESSURE HAS LIFTED WELL OFF THE COAST AS
HIGH PRESSURE BUILDS INTO THE SOUTHEAST. AFOREMENTIONED DRY AIR AND
HIGH PRESSURE WILL RESULT IN CLEARING SKIES TODAY. HOWEVER...LOW
STRATUS WILL PERSIST THROUGH MID MORNING...POSSIBLE LATER ACROSS THE
ERN SHORE. CALM WINDS...CLEARING SKIES AND RESIDUAL LOW LEVEL
MOISTURE WILL RESULT IN PATCHY FOG ACROSS THE PIEDMONT THROUGH MID
MORNING. OTHERWISE...SFC HIGH PRESSURE WILL CONTINUE TO BUILD OVER
THE SOUTHEAST TODAY...EXTENDING NEWD INTO THE MID ATLANTIC. LACK OF
STRONG CAA WILL ALLOW MODEST RECOVERS IN LOW LEVEL THICKNESS
VALUES...RESULTING IN SLIGHTLY ABOVE NORMAL DAYTIME TEMPS (LOW/MID
50S).
MEANWHILE...A SHORTWAVE AND ASSOCIATED SFC LOW WILL LIFT OVER THE
GREAT LAKES TONIGHT. A WEAK COLD FRONT WILL LOCATE OVER WRN VA AS AN
ARCTIC FRONT REACHES THE OH VALLEY BY EARLY FRIDAY MORNING. WILL
BEGIN TO SEE INCREASING CLOUDS ACROSS THE NW FA EARLY FRIDAY
MORNING. TEMPS WILL DROP INTO THE LOW 30S NW TO NEAR 40 SE UNDER
CLEAR/MOSTLY CLEAR SKIES AND LIGHT WINDS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
ADDITIONAL ENERGY WILL DIVE INTO THE UPPER MIDWEST AIDED BY A 140+
KT JET STREAK...HELPING DEEPEN THE UPPER TROUGH ACROSS THE ERN
CONUS. AFOREMENTIONED GREAT LAKES LOW WILL LIFT WELL TO THE NE AS
THE ARCTIC COLD FRONT LOCATES OVER THE OH/TN VALLEYS FRIDAY
AFTERNOON. THEREAFTER...TIMING AND SPATIAL DIFFERENCES IN LATEST
MODEL GUIDANCE WILL RESULT IN A BELOW CONFIDENCE FORECAST
BEGINNING FRIDAY NIGHT WITH FRONTAL PASSAGE AND CYCLOGENESIS ALONG
THE MID ATLANTIC COAST. TRENDED FORECAST TOWARD A GFS/ECMWF BLEND
AS NAM GUIDANCE SEEMS UNREALISTIC WITH DEVELOPING A SFC LOW TOO
FAR INLAND. THUS...COLD FRONT IS FORECAST TO CROSS THE REGION LATE
FRIDAY AS A BROAD LONGWAVE TROUGH SETTLES OVER THE ERN CONUS. WAVE
OF LOW PRESSURE WILL LIFT ALONG A COASTAL BOUNDARY FRIDAY
NIGHT...DEVELOPING INTO A COASTAL LOW OFF THE MID ATLANTIC COAST
SATURDAY MORNING AS A STRONG PV ANOMALY AND THE DEEP UPPER TROUGH
APPROACH. STRONG FRONTOGENETIC FORCING ALONG THE ARCTIC FRONT
WILL LOCATE OVER THE NW FA LATE FRIDAY NIGHT. MOISTURE WILL BE
SOMEWHAT LIMITED WITH PRECIP WATERS AOB HALF AN INCH.
HOWEVER...HIGH MODEL RH AND OMEGA AT -10C AS WELL AS GOOD DYNAMICS
(PROVIDED BY SHORTWAVE AND LOW LEVEL FRONTOGENETIC FORCING) WILL BE
ENOUGH FOR PRECIP ACROSS FA THROUGH SATURDAY MORNING. HAVE
INTRODUCED CHANCE POPS ACROSS THE PIEDMONT THROUGH THE NRN FA AND
THE ERN SHORE SATURDAY MORNING. MAIN FORECAST CHALLENGE WILL BE
TIMING OF COLD CANADIAN AIR LATE FRIDAY NIGHT/EARLY SATURDAY
MORNING. TEMPERATURE PROFILES SUGGEST ACCUMULATING SNOW OVER MUCH OF
THE PIEDMONT EARLY SATURDAY MORNING AND OVER THE NRN FA BY SUNRISE.
TEMPS WILL WARM ABOVE FREEZING SHORTLY AFTER SUNRISE TO CHANGE ALL
PRECIP OVER TO RAIN. HAVE PLACED LIGHT ACCUMULATIONS (LESS THAN
HALF AN INCH) OVER PORTIONS OF THE PIEDMONT SATURDAY MORNING. WILL
LIKELY HAVE TO ADD ADDITIONAL LIGHT ACCUMULATIONS FURTHER EAST AND
NORTH...BUT WILL WAIT FOR BETTER MODEL CONSENSUS. TEMPS FRIDAY
AFTERNOON WILL RANGE FROM THE MID/UPPER 50S TO NEAR 60 ALONG THE
COAST...SO GROUND TEMPS WILL LIMIT AMOUNT OF ACCUMULATIONS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
FOLLOWING HPC GUIDANCE FOR MOST OF THE PERIOD. THE ECMWF AND GFS
NOW SIMILAR WITH FRONT COMING THROUGH SATURDAY NIGHT. THERE IS NOW
MORE CONSENSUS IN NOT PHASING THE UPPER SYSTEM UNTIL IT IS
OFFSHORE WHICH SHOULD KEEP THE DEVELOPMENT AWAY FROM OUR AREA.
COULD STILL HAVE SOME LIGHT PRECIPITATION WITH THE STRONG FRONT AS
IT MOVES ACROSS THE AREA SATURDAY NIGHT. LOOKING AT TEMPERATURE
PROFILES...IT IS POSSIBLE THAT SOME SNOW COULD MIX WITH THE RAIN
SHOWERS AS IT PASSES THROUGH. NOT EXPECTING MANY SHOWERS AND ALL
PRECIPITATION SHOULD BE LIGHT. BY SUNDAY HIGH PRESSURE IS BUILDING
OVER THE AREA AND TEMPERATURES WILL PLUNGE WITH HIGHS MAINLY
AROUND 40. FOLLOWED HPC AND MOSGUIDE FOR TEMPERATURES AS THEY ARE
SIMILAR. NEXT UPPER TROF BEGINS TO APPROACH ON TUESDAY AND PUSHES
ANOTHER FRONT ACROSS THE AREA TUESDAY AND TUESDAY NIGHT. THERE
WILL BE ENOUGH WARM UP AHEAD OF THIS FRONT THAT ALL PRECIPITATION
SHOULD BE RAIN. HIGH TEMPERATURES WILL BE BACK INTO THE 50S.
ANOTHER COOL DOWN TO SLIGHTLY BELOW NORMAL TEMPERATURES WILL OCCUR
ON WEDNESDAY.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
LOOKING AT RAP SOUNDINGS CAN SEE ENOUGH MOISTURE IN THE BOUNDARY
LAYER FOR SOME CLOUDS AND HAVE SEEN ESPECIALLY TOWARD THE COAST A
BKN LAYER CLOSE TO 3000 FEET. THIS WILL SLOWLY LIFT AND DISSIPATE
AS THE AFTERNOON GOES ON WITH MAINLY CLEAR SKIES BY EVENING. WINDS
WILL BE VARIABLE AND LIGHT. CONTINUED VFR CONDITIONS TONIGHT AND
FRIDAY.
A STRONG COLD FRONT MOVES THROUGH THE AREA LATE FRIDAY NIGHT/EARLY
SATURDAY MORNING. THERE IS A CHANCE OF RAIN AND/OR SNOW SHOWERS
WITH THE FRONTAL PASSAGE ESPECIALLY FROM NW OF A LINE FROM RIC TO
SBY AND THIS COULD LEAD TO MVFR OR IFR CONDITIONS FOR A TIME AS
INTO SATURDAY AFTERNOON BEFORE VFR BUT BREEZY CONDITIONS RETURN
FOR THE REST OF THE WEEKEND.
&&
.MARINE...
ALL SCA FLAGS ARE NOW EXPIRED.
HIGH PRESSURE BUILDS ACROSS THE AREA TODAY AND REMAINS OFF THE
SOUTHEAST COAST THROUGH FRIDAY. LOW PRESSURE TRACKS N OF THE SAINT
LAWRENCE VALLEY THURSDAY NIGHT AND FRIDAY DRAGGING A STRONG COLD
FRONT TOWARD THE REGION FRIDAY AFTERNOON...AND ACROSS THE MID
ATLANTIC COAST LATE FRIDAY NIGHT INTO SATURDAY MORNING. SECONDARY
LOW PRESSURE DEVELOPMENT IS EXPECTED ALONG THE BOUNDARY AS IT
CROSSES THE AREA AND THIS WILL DELAY THE STRONGEST CAA UNTIL LATER
SATURDAY. INCREASED WIND SPEEDS (TO SCA OUT OF THE NW) ARE EXPECTED
ALONG WITH BUILDING WAVES/SEAS SATURDAY NIGHT INTO SUNDAY. SURFACE
HIGH PRESSURE RETURNS MONDAY RESULTING IN LIGHTER WIND AND SUBSIDING
WAVES/SEAS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SAM/TMG
NEAR TERM...SAM
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...AJZ/JAB
MARINE...AJZ
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1228 PM EST THU FEB 14 2013
.SYNOPSIS...
FAST MOVING LOW PRESSURE WILL MOVE ACROSS THE GREAT LAKES TODAY
BRINGING A CHANCE OF RAIN SHOWERS EARLY AND SNOW SHOWERS OVERNIGHT
AS A WEAK FRONT CROSSES. COLDER AIR BEHIND THE FRONT WILL PROVIDE
THE RISK FOR SNOW SHOWERS INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NOT MUCH MORE THAN FEW FLURRIES ARE BEING OBSERVED THIS
MORNING OUT AHEAD OF THE LOW PRESSURE SYSTEM CURRENTLY ANALYZED
OVER MICHIGAN. THE RUC SEEMS TO BE PICKING UP ON THESE FLURRIES
WITH MID LEVEL CLOUD DECK RIGHT AROUND THE LOWER END OF THE
DENDRITIC GROWTH ZONE HELPING TO SEED THE LOWER LEVEL STRATUS. THIS
SHOULD END SHORTLY AS WARM ADVECTION AND MIXING OUT AHEAD OF THE
LOW HELPS TO WARM TEMPERATURES ABOVE FREEZING. WITH MID-DECK
REMAINING IN PLACE HOWEVER...DIDN`T GO OVER ZEALOUS WITH THE
WARMING TODAY AND TEMPERATURES WERE KEPT CLOSE TO MET GUIDANCE.
WITH VERY LITTLE MOISTURE FOR THIS CLIPPER-LOW TO WORK WITH AS IS
APPARENT IN BOTH SATELLITE DATA AND THE MODEL RUNS...MAINTAINED
HIGHER CHANCE POPS FOR MUCH OF THE NORTHERN HALF OF THE REGION
TODAY...CLOSER TO THE LOW CENTER WHERE BETTER LIFT IS PRESENT.
PRECIPITATION SHOULD MAINLY START OUT AS RAIN THROUGH EARLY THIS
EVENING AHEAD OF THE LAGGING COLD FRONT THAT SHOULD CROSS
OVERNIGHT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
WEAK COLD ADVECTION RETURNS THURSDAY NIGHT INTO FRIDAY AS A STRONG
COLD FRONT PUSHES ACROSS THE REGION. TEMPERATURES WILL FALL WELL
BELOW NORMAL BY FRIDAY NIGHT AND CONTINUE QUITE COLD INTO
SATURDAY AS 850MB TEMPS FALL TO -18C. EXPECT SCATTERED SNOW
SHOWERS THROUGH THE PERIOD.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
PROGRESSIVE PTN IS INDICATED THROUGH THE LONG TERM PD WITH SHSN
DIMINISHING SATURDAY NGT INTO SUNDAY. WARM ADVCTN REGIME IS
EXPECTED TO MODERATE TEMPS BACK TOWARD THE AVERAGES AND ABOVE BY
MONDAY AS THE NXT UPR LVL TROF DVLPS EWD. THAT SYSTEMS CDFNT IS
PROJECTED ACRS THE REGION BY TUESDAY NGT.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
ALTHOUGH HIGH PRESSURE RIDGE IS MOVING INTO THE REGION...IFR STRATUS
REMAINS DRAPED ACROSS THE PORTS THIS AFTERNOON. LOW LEVEL MOISTURE
IS TRAPPED AT THE SURFACE...BUT SOME HEATING THIS AFTERNOON SHOULD
BRING CEILINGS BACK ABOVE 1000 FEET. A RAPIDLY MOVING COLD FRONT
PUSHING ACROSS THE GREAT LAKES TONIGHT WILL SHIFT WINDS FROM THE
SOUTH TO THE WEST AND PROVIDE A FEW GUSTS TO 20 KNOTS OVERNIGHT. THE
MVFR STRATOCU WITH AND BEHIND THE FRONT WILL PERSIST INTO FRIDAY. LITTLE
PRECIPITATION IS EXPECTED WITH THE FRONT BUT HAVE INCLUDED SOME
FLURRIES AT THE NORTHERN PORTS.
.OUTLOOK.../FRIDAY THROUGH MONDAY/...
PERIODIC RESTRICTIONS ARE PSBL THRU SUN AS SVRL FAST MOVG
DISTURBANCES MOVE THRU THE GT LKS RGN. HI PRES AND VFR CONDS RETURN
MON.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1044 AM EST THU FEB 14 2013
.SYNOPSIS...
FAST MOVING LOW PRESSURE WILL MOVE ACROSS THE GREAT LAKES TODAY
BRINGING A CHANCE OF RAIN SHOWERS EARLY AND SNOW SHOWERS OVERNIGHT
AS A WEAK FRONT CROSSES. COLDER AIR BEHIND THE FRONT WILL PROVIDE
THE RISK FOR SNOW SHOWERS INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NOT MUCH MORE THAN FEW FLURRIES ARE BEING OBSERVED THIS
MORNING OUT AHEAD OF THE LOW PRESSURE SYSTEM CURRENTLY ANALYZED
OVER MICHIGAN. THE RUC SEEMS TO BE PICKING UP ON THESE FLURRIES
WITH MID LEVEL CLOUD DECK RIGHT AROUND THE LOWER END OF THE
DENDRITIC GROWTH ZONE HELPING TO SEED THE LOWER LEVEL STRATUS. THIS
SHOULD END SHORTLY AS WARM ADVECTION AND MIXING OUT AHEAD OF THE
LOW HELPS TO WARM TEMPERATURES ABOVE FREEZING. WITH MID-DECK
REMAINING IN PLACE HOWEVER...DIDN`T GO OVER ZEALOUS WITH THE
WARMING TODAY AND TEMPERATURES WERE KEPT CLOSE TO MET GUIDANCE.
WITH VERY LITTLE MOISTURE FOR THIS CLIPPER-LOW TO WORK WITH AS IS
APPARENT IN BOTH SATELLITE DATA AND THE MODEL RUNS...MAINTAINED
HIGHER CHANCE POPS FOR MUCH OF THE NORTHERN HALF OF THE REGION
TODAY...CLOSER TO THE LOW CENTER WHERE BETTER LIFT IS PRESENT.
PRECIPITATION SHOULD MAINLY START OUT AS RAIN THROUGH EARLY THIS
EVENING AHEAD OF THE LAGGING COLD FRONT THAT SHOULD CROSS
OVERNIGHT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
WEAK COLD ADVECTION RETURNS THURSDAY NIGHT INTO FRIDAY AS A STRONG
COLD FRONT PUSHES ACROSS THE REGION. TEMPERATURES WILL FALL WELL
BELOW NORMAL BY FRIDAY NIGHT AND CONTINUE QUITE COLD INTO
SATURDAY AS 850MB TEMPS FALL TO -18C. EXPECT SCATTERED SNOW
SHOWERS THROUGH THE PERIOD.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
PROGRESSIVE PTN IS INDICATED THROUGH THE LONG TERM PD WITH SHSN
DIMINISHING SATURDAY NGT INTO SUNDAY. WARM ADVCTN REGIME IS
EXPECTED TO MODERATE TEMPS BACK TOWARD THE AVERAGES AND ABOVE BY
MONDAY AS THE NXT UPR LVL TROF DVLPS EWD. THAT SYSTEMS CDFNT IS
PROJECTED ACRS THE REGION BY TUESDAY NGT.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
ALTHOUGH HIGH PRESSURE RIDGE IS MOVING INTO THE REGION...MVFR
STRATUS REMAINS DRAPED FROM PITTSBURGH TO THE SOUTH. LOW LEVEL
MOISTURE APPEARS TO BE TRAPPED AT THE SURFACE. EXPECT THAT MVFR
CONDITIONS WILL CONTINUE AT MOST SITES...WITH MOST LOCATIONS KEEPING
THE STRATUS DECK...WITH FOG REDEVELOPING IN LOCATIONS AS STRATUS
SLOWLY MOVES TO THE EAST OVERNIGHT.
EXPECT STRATOCUMULUS TO DEVELOP ACROSS THE AREA THURSDAY. HAVE STUCK
WITH VFR CIGS IN TAFS FOR NOW...ALTHOUGH MODEL PROFILES SHOW THAT
CIGS MAY ACTUALLY DEVELOP AS HIGH MVFR INSTEAD. MOST LOCATIONS
SHOULD HAVE S-SW GUSTS TO 15-20 KTS DURING THE AFTERNOON HOURS.
STILL DO NOT HAVE ENOUGH CONFIDENCE IN PRECIPITATION CHANCES AT
FKL/DUJ TO INCLUDE IN TAFS AT THIS TIME...ALTHOUGH THIS EVENING
WOULD HAVE THE GREATEST LIKELIHOOD FOR SNOW SHOWERS.
.OUTLOOK.../FRIDAY THROUGH MONDAY/...
PERIODIC RESTRICTIONS ARE PSBL THRU SUN AS SVRL FAST MOVG
DISTURBANCES MOVE THRU THE GT LKS RGN. HI PRES AND VFR CONDS RETURN
MON.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
359 PM EST THU FEB 14 2013
.SHORT TERM...THIS EVENING AND TONIGHT
THE VORTICITY RICH POTENTIAL VORTICITY ANOMALY NOW SPINNING ACROSS
CENTRAL LAKE MICHIGAN HAS LED TO A NUMBER OF SPOKES/BANDS OF
PRECIPITATION SLIDING THROUGH LOWER MICHIGAN. SINCE MIDDAY THESE
BANDS HAVE BEEN NOTHING MORE THAN LIGHT RAIN SHOWERS OR SPRINKLES
PER SFC REPORTS AND A NEAR SURFACE MELTING LAYER AT GREATER THAN 4C.
VARIOUS HIRES MODELS ARE SUGGESTING THAT CONVECTION/SHOWER
DEVELOPMENT WILL TAKE PLACE ALONG AND AHEAD OF THE COLD FRONT
BETWEEN 21-00Z. THIS IDEA REMAINS VALID. DIFFICULT TO EVALUATE THE
OVERALL THERMODYNAMIC PROFILE OR HOW MUCH CAPE IS OUT THERE WITH THE
VALID RUC BASED SPC MESOANALYSIS GRAPHIC SHOWING NOTHING IN THE WAY
OF MUCAPE. GOING THROUGH MODEL DATA THOUGH SUGGESTS THAT 50 TO 100
J/KG IS PLAUSIBLE GIVEN SFC/DWPT VALUES THAT ARE ON TARGET.
EVOLUTION OF MODEL SOUNDINGS SUGGESTS THAT IT WILL REQUIRE SOME
COOLING FROM APPROACHING COLD FRONT TO ERODE A LOW CAPPING LAYER TO
ALLOW FOR INITIATION. THE POTENTIAL EXISTS FOR CONVECTION TO YIELD
GRAUPEL/ICE PELLETS. ADDITIONALLY...THERE REMAINS A POSSIBILITY THAT
BURSTS COULD PRODUCE MORE IN THE WAY OF SNOW...AND THE PERCENTAGE OF
OCCURRENCE IS AN UNKNOWN. FARTHER NORTH...EXPECTING THE ACTIVITY TO
FALL AS RAIN...ALTHOUGH THIS AREAS STANDS A BETTER CHANCE TO SEE
SOME LIGHT SNOW WITH MINOR ACCUMULATIONS. WINDS WILL INCREASE...UP
TO 25 TO 30 MPH...AS WIND DIRECTIONS SHIFT FROM 200 TO 240 POST COLD
FRONT.
ISENTROPIC DOWNGLIDE WILL COMMENCE BETWEEN 00-03Z...KICKING IT UP A
COUPLE OF GEARS BETWEEN 03-09Z. THE COLUMN IS SHOWN TO BECOME QUITE
STABLE IN THE 900-700MB LAYER...TOO STABLE TO SUPPORT MUCH IN THE
WAY OF SNOW TONIGHT. NAM IS HIGHLIGHTING SOME LAKE EFFECT
BANDING/ENHANCED CONVERGENCE ACROSS SW LOWER LATE TONIGHT. DID LEAVE
A LOW CHANCE FOR LIGHT IN ACROSS THE SOUTH AS THERE IS SOME
POTENTIAL FOR SOME SNOWFLAKES TO MAKE THE TRIP ACROSS THE PENINSULA.
OTHERWISE...FLURRIES FOR A MAJORITY OF THE AREA. LOWS TONIGHT WERE
DERIVED FROM A BLEND OF RAW MODEL OUTPUT...A DECENT ADJUSTMENT
DOWNWARD UPPER TEENS NORTH TO UPPER 20S SOUTH.
&&
.LONG TERM...FRIDAY THROUGH NEXT THURSDAY
LONGWAVE TROUGH WILL LOCK COOL AIR IN PLACE OVER THE GREAT LAKES
THROUGH THE WEEKEND...AS H850 TEMPS DROP TO AROUND -18C (BY SAT
NIGHT) IN THE POST-FRONTAL AIRMASS. CHANCES FOR ACCUMULATING SNOW
LOOK FAIRLY LOW FOR THIS SIDE OF THE STATE...AND WILL BE DUE TO A
COMBINATION OF WEAK SHORTWAVES AND LAKE EFFECT. SHORTWAVES MAY BE A
LITTLE HARD TO TIME DUE TO SMALL NATURE AND LACK OF SAMPLING (AT
THIS TIME) AND FORECAST ADJUSTMENTS ARE STILL POSSIBLE AS CHANGES IN
TIMING/LOCATION OF SHORTWAVES IMPACT LAKE EFFECT PARAMETERS SUCH AS
STABILITY...MOISTURE...AND WIND SPEED AND TRAJECTORY.
MODEL GUIDANCE TAKES THE WAVE NOW DROPPING THROUGH SOUTHERN MANITOBA
ACROSS NORTHERN LOWER MICHIGAN TOMORROW...WHILE ALSO SHEARING APART
ANOTHER SHORTWAVE AS IT DROPS FROM THE DAKOTAS DOWN INTO THE OHIO
VALLEY. VERY WEAK LIFT ASSOCIATED WITH THESE WAVES COULD PROVIDE A
BRIEF SNOW SHOWER TO THE AREA...BUT MAINLY EXPECT A LOT OF CLOUDS
AND FLURRIES AROUND DUE TO LAKE EFFECT AND STEEP LAPSE RATES. DID
KEEP LOW POPS IN THE FORECAST...BUT THINK FAIRLY WEAK FLOW OVER THE
LAKE AND ONLY MODERATE INSTABILITY SHOULD KEEP ACCUMULATIONS TO OUR
WEST. SIMILAR POP FORECAST EXISTS ON FRIDAY NIGHT. ALTHOUGH MOISTURE
DEPTH AND COLD AIR ADVECTION WILL INCREASE...MEAN SURFACE-850MB FLOW
ACROSS LAKE MICHIGAN WILL ONLY RUN 10-15 KNOTS...AND WILL TURN A
LITTLE MORE TO THE NORTHWEST. AGAIN WOULD EXPECT MOSTLY
FLURRIES...AND ONLY LOW CHANCES FOR LIGHT ACCUMULATIONS SOUTH OF A
LINE FROM HOWELL TO DETROIT.
POTENTIAL FOR LIGHT SNOW LOOKS A LITTLE BETTER ON SATURDAY AS A
SHORTWAVE TROUGH AXIS CLIPS ACROSS THE AREA. LAKE EFFECT ENHANCEMENT
ALSO LOOKS MORE LIKELY AS EQUILIBRIUM HEIGHTS OVER LAKE
MICHIGAN HIT THEIR PEAK AROUND 12KFT AND LAKE TO H850 DELTA T VALUES
RISE TO OVER 20 C. LIMITING FACTORS FOR THIS SIDE OF THE STATE ONCE
AGAIN WILL BE LIGHT FLOW AND WINDS TURNING MORE TO THE
NORTH-NORTHWEST. WOULD EXPECT FLURRIES AND SCATTERED LIGHT SNOW
SHOWERS ACROSS THE AREA IN THIS SET-UP...WITH BETTER POTENTIAL
(HIGHER POPS) SOUTH OF M-59 WHERE CONVERGENCE SHOULD BE BETTER.
LONGWAVE TROUGH WILL PUSH TO THE EAST COAST DURING THE SECOND HALF
OF THE WEEKEND...ALLOWING AN UPSTREAM RIDGE TO SLIDE IN OVERHEAD
SUNDAY INTO MONDAY. ENERGY DIVING OUT OF THE GULF OF ALASKA WILL
DROP THROUGH THE CENTRAL ROCKIES MONDAY...PULLING ADDITIONAL ENERGY
OUT OF THE SOUTHERN STREAM BEFORE IT BECOMES MORE ORGANIZED AND
DEEPENS OVER THE GREAT LAKES MONDAY NIGHT AND TUESDAY (AIDED BY GOOD
HEIGHT FALLS AND STRONG JET DYNAMICS). TRENDS WITH THE EURO AND GFS
HAVE BEEN TO SHIFT THIS SYSTEM FURTHER NORTH OVER THE PAST 24
HOURS...WITH A SURFACE LOW CENTER TRACK MORE ACROSS CENTRAL OR
NORTHERN MICHIGAN. GIVEN THAT THE GEM AND UKMET ARE STILL FURTHER
SOUTH WITH THE TRACK...MADE JUST MINOR ADJUSTMENTS TO PRECIPITATION
TYPE THIS FORECAST CYCLE TO INCREASE RAIN POTENTIAL. 14.12Z EURO/GFS
SOLUTIONS NOW SUPPORT ALL RAIN MONDAY NIGHT BEFORE A CHANGEOVER TO
SNOW BEHIND A STRONG COLD FRONT ON TUESDAY. ACCUMULATIONS STILL LOOK
POSSIBLE...BUT MAY BE DELAYED UNTIL TUESDAY.
&&
.MARINE...
LOW PRESSURE WILL TRACK THROUGH LOWER MICHIGAN THIS AFTERNOON AND
ACROSS NORTHERN LAKE HURON THIS EVENING. CURRENT SURFACE
OBSERVATIONS IN THE INCREASED GRADIENT PORTION OF THE SURFACE LOW IS
SUPPORTING WIND GUSTS OF UP TO 30 KNOTS. WITH NO EXPECTED
DEEPENING/ACTUAL MIDLEVEL WEAKENING RATES WILL CANCEL THE GALE WATCH
AND FORGO A GALE WARNING. THIS IS ALSO SUPPORTED BY THE VERY BRIEF
DURATION TIME. HOWEVER...WITH THE COLD NORTHWEST FLOW FOLLOWING THE
CYCLONE...DID ISSUE A BRISK WIND ADVISORY FOR ALL NEARSHORE ZONES.
WINDS WILL WEAKEN ON FRIDAY AS ARCTIC HIGH PRESSURE BUILDS INTO THE
WESTERN GREAT LAKES REGION. THIS HIGH WILL KEEP RELATIVELY LIGHT
WINDS ON THE LAKES THROUGH THE WEEKEND. A LOW PRESSURE SYSTEM IS
FORECAST TO INTENSIFY OVER THE GREAT LAKES REGION MONDAY NIGHT INTO
TUESDAY AND WILL OFFER THE NEXT CHANCE FOR STRONG WINDS.
&&
.AVIATION...ISSUED 104 PM EST THU FEB 14 2013
//DISCUSSION...
THE CLOSED MIDLEVEL LOW CIRCULATION NOW ROUNDING INTO MID LOWER
MICHIGAN WILL PUSH INITIAL PRECIPITATION ACTIVITY EAST OF THE AREA.
IN FACT...ALL TERMINALS ARE CURRENTLY REPORTING NO PRECIPITATION.
OUTSIDE OF A COUPLE ROGUE SPRINKLES...EXPECT DRY CONDITIONS FOR THE
NEXT 3 HOURS. THE NEXT FEATURE TO MONITOR WILL BE AN ATTENDANT COLD
FRONT THAT WILL SWING THROUGH SOUTHEASTERN MICHIGAN BETWEEN 21-00Z.
FORCING ALONG AND AHEAD OF THE COLD FRONT IS EXPECTED TO ACT ON
INCREASING LOWER ATMOSPHERIC INSTABILITY TO CAUSE SHOWERS/CONVECTION
TO INITIATE OVERHEAD. PRECIPITATION RATES WITHIN THE CONVECTION COULD
YIELD GRAUPEL OR ICE PELLETS. SOME QUESTION AS TO HOW WARM THE NEAR
SURFACE LAYER WILL GET...WHICH BRINGS SOME PRECIPITATION TYPE
CONCERNS. KEPT A SNOW MENTION IN WITH CONVECTIVE RAIN/PL AT
KFNT...WHILE MAINTAINED AN ALL SNOW MENTION AT KMBS. THE STRENGTH OF
THE COLD AIR ADVECTION MAY SUPPORT A GOOD WESTERLY POP OF WIND POST
COLD FRONT...POTENTIALLY UP TO 30 KNOTS.
FOR DTW...CONFIDENCE HAS INCREASED THAT CONVECTIVE RAIN SHOWERS WILL
DEVELOP ALONG AN APPROACHING COLD FRONT. THIS IS EXPECTED TO OCCUR
BETWEEN 21-00Z. GRAUPEL OR PL WILL BE POSSIBLE IN THE HEAVIEST
CONVECTIVE CELLS. AFTER THE COLD FRONT...CONDITIONS WILL QUIET DOWN
THIS EVENING BEFORE LIGHT SNOW SHOWERS/FLURRIES BECOME POSSIBLE
AGAIN AFTER 7Z.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING HEIGHTS BELOW 5000 FEET THROUGHOUT MUCH
IF NOT ALL OF THE TAF PERIOD.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
BRISK WIND ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING SAGINAW BAY...FROM 7 PM THURSDAY TO 10 AM
FRIDAY.
LAKE ST CLAIR...
BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY.
MI WATERS OF LAKE ERIE...
BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY.
&&
$$
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
AVIATION.....CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1243 PM EST THU FEB 14 2013
.UPDATE...
ISSUED AT 947 AM EST THU FEB 14 2013
NO CHANGES PLANNED TO THE ONGOING HEADLINES THIS MORNING. SNOWFALL
REPORTS ACROSS NORTHEAST WI AND SOUTHERN MENOMINEE COUNTY HAVE BEEN
AROUND 3 INCHES. WITH MODERATE SNOW EXPECTED TO CONTINUE FOR
ANOTHER FEW HOURS...THE GOING 3 TO 5 INCH FORECAST LOOKS ON TRACK.
THE ONE LOCATION WHERE AMOUNTS MAY END UP A LITTLE HIGHER THAT
PREVIOUSLY FORECAST IS ACROSS SOUTHERN DELTA AND SCHOOLCRAFT
COUNTIES...MAINLY OVER THE GARDEN AND STONINGTON PENINSULAS...WHERE
THE SNOW RATIOS HAVE BEEN A LITTLE HIGHER THAN FARTHER SOUTH.
REPORTS OF 1.5 TO 2 INCHES HAVE BEEN COMMON ALONG LAKE MI. WITH
ANOTHER INCH OR SO POSSIBLE WITH A HEAVIER BAND OF SNOW FOCUSED
UNDER 900 TO 850MB FRONTOGENESIS. WILL ISSUE A SPECIAL WX STATEMENT
FOR THOSE LOCATIONS FOR LOCAL SNOW AMOUNTS UP TO 3 INCHES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 448 AM EST THU FEB 14 2013
ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH
WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN
LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO
MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO.
STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A
SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE
THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO
BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO
SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO
THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS
LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND
ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING.
FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND
NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL
UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST
PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN
CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB
FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE
LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE
ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH
THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN
HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY
KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN
AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND
SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE
MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1
WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR
BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN
THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE
COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE
THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS
5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH
NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK
TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION
AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE
HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR
LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW
THINGS EVOLVED BEFORE ISSUING AN SPS.
AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO
SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE
SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE
ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED
LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO
PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND
DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME
FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME
CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE
DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION
HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE
CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL
LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL
CLIMATOLOGY POPS.
EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST
FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE
THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER
THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ.
LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID
TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD
WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY
FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL
TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES
TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER
FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE
DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE
FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 448 AM EST THU FEB 14 2013
AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG
TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL
GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE
MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS
CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM
SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER
ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN
STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT
LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE
STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS...
ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS
THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT
PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE
GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE
SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER
THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT
LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT
LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE
FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS...
BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS
FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE
GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING
MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE
WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW
TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL
FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK.
HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE
SEEN.
MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES
FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE
RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL
NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT.
LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME
INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES.
INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL
STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI
NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM
FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES.
SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW
WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE
CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE
PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST
SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN
THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E
HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ
HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT...
EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS
POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS
FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA
FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN
SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING
ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE
POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR
MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE
A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE
OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN
THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY
PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS
FCST ISSUANCE.
SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE
PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS
WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E.
AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL
SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT
UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR
SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS
COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO
-15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD
BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E.
IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME
TRADITIONAL COLD SPOTS MAY FALL BLO -20F.
SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF
NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG
WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD
STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A
DRY DAY SUN.
TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING
THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND
WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT
LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO
BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS
THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE
ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT
APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP
HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS
SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A
BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO
THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER
ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE
CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN
CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE
INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES
WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO
THE UPPER MISSISSIPPI VALLEY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1242 PM EST THU FEB 14 2013
AN INITIAL BURST OF LAKE-ENHANCED SNOW ON THE BACKSIDE OF A
DEPARTING CLIPPER SYSTEM IS RESULTING IN CIGS AND VIS ON THE
LIFR/IFR THRESHOLD AT ALL SITES. EXPECT VIS TO IMPROVE AND -SHSN TO
DIMINISH THIS AFTERNOON AS MOISTURE FROM THE SYSTEM PULLS OUT OF THE
AREA. THEN LATE TONIGHT...LES INTENSITY WILL INCREASE AT MAINLY IWD
AND CMX AS WNW TO NW WINDS BRING ARCTIC AIR OVER LAKE SUPERIOR. VIS
WILL FALL TO NEAR LIFR LEVELS...AND WILL LIKELY DROP LOWER AT TIMES
UNDER HEAVIER LES BANDS ON FRIDAY. IWD HAS THE BIGGEST QUESTION MARK
AS IT LOOKS LIKE A SIGNIFICANT LES BAND WILL SET UP JUST NORTH OF
THE TERMINAL. IF THIS BAND DRIFTS SOUTH AT TIMES FRIDAY
MORNING...VIS COULD FALL BELOW AIRFIELD LANDING MINS FOR AN EXTENDED
PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 448 AM EST THU FEB 14 2013
A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL
SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS
THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT
RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER
THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH
TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY
FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR
PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON
SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS
BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR
ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO
INCREASE TO 20-25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY
AFTERNOON FOR MIZ006-085.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST
SATURDAY FOR LSZ264>266.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...TK
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...TK
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
951 AM EST THU FEB 14 2013
.UPDATE...
ISSUED AT 947 AM EST THU FEB 14 2013
NO CHANGES PLANNED TO THE ONGOING HEADLINES THIS MORNING. SNOWFALL
REPORTS ACROSS NORTHEAST WI AND SOUTHERN MENOMINEE COUNTY HAVE BEEN
AROUND 3 INCHES. WITH MODERATE SNOW EXPECTED TO CONTINUE FOR
ANOTHER FEW HOURS...THE GOING 3 TO 5 INCH FORECAST LOOKS ON TRACK.
THE ONE LOCATION WHERE AMOUNTS MAY END UP A LITTLE HIGHER THAT
PREVIOUSLY FORECAST IS ACROSS SOUTHERN DELTA AND SCHOOLCRAFT
COUNTIES...MAINLY OVER THE GARDEN AND STONINGTON PENINSULAS...WHERE
THE SNOW RATIOS HAVE BEEN A LITTLE HIGHER THAN FARTHER SOUTH.
REPORTS OF 1.5 TO 2 INCHES HAVE BEEN COMMON ALONG LAKE MI. WITH
ANOTHER INCH OR SO POSSIBLE WITH A HEAVIER BAND OF SNOW FOCUSED
UNDER 900 TO 850MB FRONTOGENESIS. WILL ISSUE A SPECIAL WX STATEMENT
FOR THOSE LOCATIONS FOR LOCAL SNOW AMOUNTS UP TO 3 INCHES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 448 AM EST THU FEB 14 2013
ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH
WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN
LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO
MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO.
STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A
SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE
THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO
BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO
SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO
THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS
LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND
ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING.
FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND
NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL
UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST
PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN
CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB
FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE
LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE
ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH
THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN
HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY
KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN
AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND
SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE
MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1
WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR
BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN
THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE
COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE
THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS
5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH
NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK
TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION
AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE
HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR
LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW
THINGS EVOLVED BEFORE ISSUING AN SPS.
AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO
SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE
SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE
ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED
LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO
PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND
DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME
FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME
CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE
DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION
HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE
CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL
LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL
CLIMATOLOGY POPS.
EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST
FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE
THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER
THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ.
LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID
TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD
WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY
FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL
TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES
TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER
FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE
DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE
FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 448 AM EST THU FEB 14 2013
AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG
TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL
GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE
MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS
CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM
SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER
ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN
STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT
LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE
STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS...
ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS
THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT
PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE
GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE
SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER
THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT
LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT
LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE
FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS...
BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS
FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE
GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING
MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE
WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW
TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL
FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK.
HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE
SEEN.
MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES
FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE
RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL
NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT.
LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME
INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES.
INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL
STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI
NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM
FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES.
SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW
WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE
CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE
PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST
SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN
THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E
HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ
HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT...
EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS
POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS
FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA
FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN
SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING
ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE
POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR
MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE
A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE
OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN
THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY
PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS
FCST ISSUANCE.
SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE
PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS
WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E.
AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL
SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT
UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR
SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS
COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO
-15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD
BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E.
IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME
TRADITIONAL COLD SPOTS MAY FALL BLO -20F.
SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF
NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG
WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD
STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A
DRY DAY SUN.
TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING
THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND
WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT
LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO
BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS
THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE
ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT
APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP
HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS
SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A
BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO
THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER
ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE
CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN
CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE
INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES
WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO
THE UPPER MISSISSIPPI VALLEY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 639 AM EST THU FEB 14 2013
A LOW PRESSURE SYSTEM EXITING CENTRAL WISCONSIN THIS MORNING WILL
PRODUCE LIGHT SNOW SHOWERS AT KSAW FOR THE FIRST COUPLE OF HOURS
OF THE FORECAST. FOCUS THEN TURNS TO LAKE ENHANCED SNOW FOR A
PERIOD TODAY...A BRIEF LULL DURING LATE AFTERNOON AND EARLY
EVENING BEFORE LAKE EFFECT ARRIVES FOR NORTH-NORTHWEST WIND
LOCATIONS.
WILL CONTINUE IDEA OF LOWER VISIBILITIES AND CEILINGS WITH LAKE
ENHANCED SNOW THROUGH THIS AFTERNOON AT ALL SITES. BUT AS THE LOW
QUICKLY DEPARTS THIS AFTERNOON...SUPPORTING DEEP MOISTURE DEPARTS
AND EXPECT WEAKENING SNOW SHOWERS INTO THE EVENING. BUT WITH COLDER
AIR INCREASING THROUGH THE NIGHT...SHOULD SEE LAKE EFFECT SNOW
INTENSIFY AT KIWD/KCMX THROUGH THE NIGHT. KSAW ON THE OTHER HAND
WON/T SEE TOO FAVORABLE WIND DIRECTIONS AND HAVE JUST WENT WITH
MVFR CEILINGS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 448 AM EST THU FEB 14 2013
A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL
SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS
THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT
RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER
THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH
TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY
FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR
PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON
SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS
BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR
ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO
INCREASE TO 20-25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY
AFTERNOON FOR MIZ006-085.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST
SATURDAY FOR LSZ264>266.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...TK
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
640 AM EST THU FEB 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 448 AM EST THU FEB 14 2013
ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH
WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN
LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO
MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO.
STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A
SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE
THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO
BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO
SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO
THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS
LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND
ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING.
FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND
NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL
UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST
PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN
CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB
FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE
LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE
ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH
THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN
HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY
KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN
AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND
SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE
MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1
WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR
BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN
THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE
COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE
THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS
5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH
NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK
TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION
AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE
HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR
LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW
THINGS EVOLVED BEFORE ISSUING AN SPS.
AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO
SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE
SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE
ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED
LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO
PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND
DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME
FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME
CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE
DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION
HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE
CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL
LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL
CLIMATOLOGY POPS.
EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST
FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE
THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER
THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ.
LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID
TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD
WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY
FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL
TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES
TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER
FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE
DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE
FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 448 AM EST THU FEB 14 2013
AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG
TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL
GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE
MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS
CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM
SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER
ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN
STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT
LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE
STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS...
ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS
THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT
PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE
GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE
SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER
THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT
LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT
LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE
FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS...
BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS
FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE
GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING
MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE
WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW
TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL
FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK.
HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE
SEEN.
MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES
FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE
RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL
NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT.
LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME
INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES.
INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL
STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI
NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM
FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES.
SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW
WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE
CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE
PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST
SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN
THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E
HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ
HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT...
EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS
POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS
FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA
FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN
SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING
ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE
POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR
MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE
A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE
OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN
THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY
PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS
FCST ISSUANCE.
SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE
PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS
WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E.
AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL
SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT
UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR
SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS
COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO
-15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD
BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E.
IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME
TRADITIONAL COLD SPOTS MAY FALL BLO -20F.
SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF
NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG
WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD
STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A
DRY DAY SUN.
TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING
THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND
WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT
LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO
BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS
THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE
ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT
APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP
HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS
SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A
BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO
THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER
ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE
CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN
CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE
INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES
WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO
THE UPPER MISSISSIPPI VALLEY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 639 AM EST THU FEB 14 2013
A LOW PRESSURE SYSTEM EXITING CENTRAL WISCONSIN THIS MORNING WILL
PRODUCE LIGHT SNOW SHOWERS AT KSAW FOR THE FIRST COUPLE OF HOURS
OF THE FORECAST. FOCUS THEN TURNS TO LAKE ENHANCED SNOW FOR A
PERIOD TODAY...A BRIEF LULL DURING LATE AFTERNOON AND EARLY
EVENING BEFORE LAKE EFFECT ARRIVES FOR NORTH-NORTHWEST WIND
LOCATIONS.
WILL CONTINUE IDEA OF LOWER VISIBILITIES AND CEILINGS WITH LAKE
ENHANCED SNOW THROUGH THIS AFTERNOON AT ALL SITES. BUT AS THE LOW
QUICKLY DEPARTS THIS AFTERNOON...SUPPORTING DEEP MOISTURE DEPARTS
AND EXPECT WEAKENING SNOW SHOWERS INTO THE EVENING. BUT WITH COLDER
AIR INCREASING THROUGH THE NIGHT...SHOULD SEE LAKE EFFECT SNOW
INTENSIFY AT KIWD/KCMX THROUGH THE NIGHT. KSAW ON THE OTHER HAND
WON/T SEE TOO FAVORABLE WIND DIRECTIONS AND HAVE JUST WENT WITH
MVFR CEILINGS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 448 AM EST THU FEB 14 2013
A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL
SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS
THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT
RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER
THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH
TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY
FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR
PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON
SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS
BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR
ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO
INCREASE TO 20-25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY
AFTERNOON FOR MIZ006-085.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST
SATURDAY FOR LSZ264>266.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
449 AM EST THU FEB 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 448 AM EST THU FEB 14 2013
ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH
WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN
LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO
MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO.
STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A
SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE
THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO
BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO
SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO
THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS
LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND
ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING.
FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND
NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL
UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST
PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN
CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB
FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE
LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE
ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH
THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN
HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY
KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN
AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND
SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE
MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1
WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR
BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN
THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE
COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE
THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS
5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH
NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK
TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION
AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE
HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR
LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW
THINGS EVOLVED BEFORE ISSUING AN SPS.
AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO
SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE
SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE
ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED
LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO
PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND
DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME
FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME
CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE
DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION
HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE
CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL
LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL
CLIMATOLOGY POPS.
EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST
FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE
THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER
THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ.
LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID
TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD
WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY
FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL
TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES
TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER
FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE
DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE
FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 448 AM EST THU FEB 14 2013
AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG
TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL
GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE
MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS
CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM
SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER
ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN
STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT
LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE
STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS...
ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS
THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT
PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE
GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE
SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER
THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT
LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT
LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE
FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS...
BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS
FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE
GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING
MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE
WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW
TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL
FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK.
HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE
SEEN.
MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES
FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE
RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL
NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT.
LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME
INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES.
INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL
STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI
NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM
FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES.
SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW
WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE
CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE
PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST
SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN
THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E
HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ
HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT...
EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS
POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS
FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA
FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN
SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING
ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE
POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR
MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE
A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE
OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN
THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY
PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS
FCST ISSUANCE.
SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE
PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS
WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E.
AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL
SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT
UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR
SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS
COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO
-15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD
BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E.
IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME
TRADITIONAL COLD SPOTS MAY FALL BLO -20F.
SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF
NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG
WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD
STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A
DRY DAY SUN.
TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING
THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND
WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT
LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO
BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS
THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE
ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT
APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP
HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS
SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A
BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO
THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER
ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE
CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN
CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE
INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES
WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO
THE UPPER MISSISSIPPI VALLEY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1222 AM EST THU FEB 14 2013
CMX/IWD...EXPECT MVFR CONDITIONS TO PREDOMINATE AT THESE LOCATIONS
THRU THIS MRNG WITH AREA OF HEAVIER SN ON NRN FLANK OF CLIPPER LO
MOVING INTO WI REMAINING TO THE S. AS COLDER AIR ARRIVES THIS AFTN
ON THE HEELS OF A GUSTY NNW WIND...EXPECT SOME LES TO DVLP WITH VSBY
FALLING TO IFR UNDER SOME OF THE HEAVIER SHSN...ESPECIALLY AT IWD
WITH LONGER FETCH/MORE FVRBL UPSLOPE FLOW.
SAW...EVEN THOUGH HEAVIER SN ASSOCIATED WITH CLIPPER LO MOVING THRU
WI WL REMAIN TO THE S...EXPECT IFR CONDITIONS TO PREDOMINATE THRU
THIS MRNG WITH UPSLOPE NNE FLOW OFF LK SUP BRINGING LO CLDS/SOME
-SN. CONDITIONS WL IMPROVE TO MVFR LATER TDAY AS THE FLOW BACKS
SUFFICIENTLY TO A DOWNSLOPING NNW FLOW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 448 AM EST THU FEB 14 2013
A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL
SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS
THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT
RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER
THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH
TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY
FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR
PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON
SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS
BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR
ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO
INCREASE TO 20-25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY
AFTERNOON FOR MIZ006-085.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST
SATURDAY FOR LSZ264>266.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS JACKSON MS
910 PM CST FRI FEB 15 2013
.UPDATE...LATEST SURFACE ANALYSIS HAS THE COLD FRONT SOUTH OF OUR
CWA WITH HIGH PRESSURE CENTERED OVER THE PLAINS. THE PRESSURE
GRADIENT AROUND THE HIGH WILL KEEP A COOL NORTH WIND OVER OUR AREA
THROUGH THE NIGHT. WATER VAPOR IMAGERY/RUC ANALYSIS HAS THE UPPER
LEVEL TROUGH AXIS SWINGING THROUGH THE SOUTHERN PLAINS. VERY COLD
AIR WAS ASSOCIATED WITH THE TROUGH INCLUDING TEMPS COOLER THAN -30C
AT 50H. RUC ANALYSIS WAS SHOWING THE 850MB ZERO DEGREE ISOTHERM NEAR
A NATCHEZ TO JACKSON TO MACON LINE. THIS WAS COLLOCATED WITH A BAND
OF MID LEVEL CLOUDS THAT LOCAL RADARS SUGGEST MAY DROP A FEW
SPRINKLES AT TIMES. NORTHWEST OF THIS BAND OVER OUR DELTA REGION
ONLY A FEW HIGH THIN CIRRUS CLOUDS WERE NOTED. LOOKING AT THE 00Z
JAN SOUNDING AND RUC ANALYSIS HAVE DECIDED TO REMOVE ANY MENTION OF
FLURRIES TONIGHT. ANY WET BULB COOLING AFFECTS SHOULD BE NORTH OF
THE SPRINKLES. THE BAND OF MID LEVEL CLOUDS WILL CONTINUE TO
GRADUALLY SHIFT SOUTHEAST THROUGH THE NIGHT. IT WILL BE COLDER
TONIGHT WITH MORNING LOWS AT OR BELOW FREEZING OVER THE NORTHERN
THIRD OF THE AREA. OUR SOUTHEAST MOST ZONES MAY BOTTOM OUT NEAR 40
DEGREES BUT MOST OF THE AREA WILL BE IN THE 30S AT DAYBREAK. /22/
&&
.AVIATION...NW WINDS OF 5-6KTS WILL CONTINUE TONIGHT. NW WINDS WILL
INCREASE SATURDAY TO 10-15KTS WITH GUSTS OF 20KTS BY 17Z.
OTHERWISE...VFR CONDS WILL PERSIST THROUGH SATURDAY NIGHT. /22/
&&
.PREV DISCUSSION... /ISSUED 405 PM CST FRI FEB 15 2013/
DISCUSSION...IT HAS TURNED OUT TO BE A RATHER PLEASANT DAY ACROSS A
GOOD PORTION OF THE REGION...DESPITE A COLD FRONT PUSHING THROUGH
THE HEART OF THE LOWER MISSISSIPPI VALLEY. THIS FRONT HAS BEEN
ACCOMPANIED BY A FEW CLOUDS FROM TIME TO TIME...BUT THE THICKEST
CLOUDS HAVE ONLY STARTED MOVING INTO WESTERN AND NORTHWEST ZONES IN
THE PAST FEW YOURS. THESE CLOUDS COULD BEGIN PRODUCING SOME
SPRINKLES AND PERHAPS EVEN A LIGHT SHOWER OR TWO TONIGHT ACROSS OUR
REGION DUE TO COMBINATION OF LIFT FROM LOW LEVEL COLD AIR ADVECTION
AND THE PROXIMITY OF A LARGE UPPER TROUGH OF LOW PRESSURE. PRECIP
SHOULD NOT BE AT ALL HEAVY (IF YOU INDEED GET IT) DUE TO LACK OF
MOISTURE AND CYCLOGENESIS. A LARGER STICKING POINT IS WHETHER OR NOT
TO INCLUDE MENTION OF SNOW FLURRIES IN THE FORECAST BECAUSE PROGGED
COLUMN TEMPS SUGGEST LEAST A MIX OF A FEW WET AND SMALL SNOWFLAKES
LATE TONIGHT FOR AREAS ROUGHLY ALONG THE I-20 CORRIDOR AND NORTHEAST
TOWARD THE GOLDEN TRIANGLE. IF SOME FLAKES DO FLY IN A FEW OF THESE
AREAS IT SHOULD TRULY BE QUITE LIGHT AND THUS INCAPABLE OF STICKING
TO SURFACES SINCE GROUND TEMPS IN AREAS AFFECTED SHOULD BE ABOVE
FREEZING.
THE POTENTIAL PROSPECT FOR ANOTHER SNOWFLAKE OR TWO (MIXED WITH RAIN
SHOWERS) WILL REMAIN FOR LOCATIONS UP NEAR THE HIGHWAY 82 CORRIDOR
THROUGH THE FIRST HALF OF THE DAY TOMORROW. THE MECHANISM FOR THIS
LITTLE BIT OF LOW LEVEL CONVECTIVE SHOWERS WILL BE MINOR AND GROWING
MORE INSIGNIFICANT THROUGHOUT THE DAY SINCE THE PREVIOUSLY-MENTIONED
UPPER TROUGH AXIS WILL BE PULLING OFF TO THE EAST. OTHERWISE...
ANTICIPATE PARTLY CLOUDY SKIES AT WORST WITH A STIFF NORTHWEST
BREEZE WORSENING THE AMBIENT CHILLS AS HIGHS RANGE FROM THE UPPER
40S TO MID 50S.
THE TOMORROW NIGHT THROUGH SUNDAY PERIOD LOOKS TO REMAIN RATHER
BENIGN AS SHORT WAVE RIDGING (AND ASSOCIATED SURFACE HIGH PRESSURE)
TAKES SHAPE BEHIND THE DEPARTING TROUGH AND THE ENERGY COMING TOWARD
THE REGION FOR MONDAY. TEMPERATURES WILL GENERALLY TREND A LITTLE
COOLER THAN AVERAGE OVER THIS 36 HOUR PERIOD WITH POTENTIAL FOR A
SOLID FREEZE (LOWS IN THE 20S) FOR MANY AREAS SATURDAY NIGHT OR
REALLY EARLY SUNDAY. WENT WITH MAV GUIDANCE LOWS FOR NOW WITH LITTLE
ADJUSTMENT. HOWEVER...MID LEVEL CLOUDS TRYING TO STREAM IN FROM THE
NORTH MAY WORK TO LIMIT RADIATIONAL COOLING POTENTIAL NORTH OF I-20
SATURDAY NIGHT AND THEREFORE AT LEAST THESE LOCATIONS HAVE A LITTLE
POSSIBILITY OF VERIFYING WARMER THAN ADVERTISED. SUNDAY INTO SUNDAY
NIGHT WILL DEFINITELY BE WARMER THAN SATURDAY WITH WINDS TURNING
AROUND TO THE SOUTH IN ADVANCE OF A QUICK-HITTING RAIN MAKER SLATED
FOR THE START OF THE WORK WEEK. /BB/
PREV DISCUSSION... /ISSUED 438 AM CST FRI FEB 15 2013/
LONG TERM...THE LONG TERM WILL FEATURE TWO SYSTEMS...THE FIRST
ARRIVING LATE MON AFTERNOON INTO MON NGT AND THE SECOND MORE POTENT
SYSTEM FOR THU-THU NGT.
FOR MON INTO MON NGT...A SOLID TROUGH WILL PROGRESS THROUGH THE
CENTRAL CONUS AND HELP PUSH A COLD FRONT ACROSS THE REGION. IN
ADVANCE OF THE SYSTEM...DEEPER MOISTURE WILL INCREASE AND SUPPORT
HIGH RAIN CHANCES BY MON NGT. MODEL TRENDS ARE DEVELOPING PRECIP IN
THE INCREASING WAA REGIME SOONER AND THUS WILL CONTINUE TO TREND
UPWARD WITH POPS FOR LATE MON AFTERNOON. STILL...THE BEST COMBO OF
CONVERGENCE AND LIFT WILL BE DURING THE MON NGT PERIOD. GUID DATA
HAS BEEN ROCK SOLID ON TIMING AND CONTINUE TO STRONGLY SUPPORT
PRECIP FOR THE NGT PERIOD. DUE TO THIS...HAVE INCREASED POPS TO
CATEGORICAL. MODEL DATA DOES SHOW A BIT OF ELEVATED INSTABILITY...
ENOUGH TO SUPPORT ISO TSRA AND HAVE WORDED THE WEATHER AS SUCH. AS
FOR HEAVY RAIN POTENTIAL...THIS RISK SEEMS LOW AT THIS POINT DUE TO
LACK OF HIGH QUALITY GULF MOISTURE BEING IN PLACE...THE LACK OF
INSTABILITY(EFFICIENT DEEP CONVECTION) AND THE PROGRESSIVE NATURE OF
THE RAIN AREA. THE AREA LOOKS TO SEE .5 TO 1.0 INCH OF PRECIP. WHILE
THE REGION HAS BE EXCEPTIONALLY WET OF LATE...WE SHOULD BE ABLE TO
HANDLE THIS SORT OF PRECIP. DUE TO THIS...WILL REMOVE THE MENTION OF
HEAVY RAIN AND FLOODING POTENTIAL.
I EXPECT MOST OF THE PRECIP TO BE OUT OF THE CWA STARTING THE TUE
PERIOD. WILL HOLD ON TO SOME LOW END POPS ACROSS THE EAST FOR JUST
THE FIRST COUPLE HRS...THEN DRY THINGS. THE AIRMASS FOR MID WEEK
LOOKS TO BRING NORMAL TYPE CONDITIONS. AS FOR TEMPS...CONTINUED TO
USE A BLEND OF THE GFS AND THE OTHER COOLER GUID DATA SETS.
FOR LATE WEEK...MODELS CONTINUE TO ADVERTISE THE POTENTIAL FOR A
POTENT SYSTEM. TIMING HAS BEEN QUITE GOOD AND CONSISTENT FOR BEING
THIS FAR OUT. THE FOCUS HAS BEEN ON THU AND THU NGT FOR A ROUND OF
STORMS TO IMPACT THE REGION. THE OVERALL SETUP LOOKS VERY SPRING
LIKE AND SUPPORTIVE OF SEVERE WEATHER. DUE TO MODEL CONSISTENCY AND
HIGHER CONFIDENCE THAN NORMAL FOR 6-7 DAYS OUT...WILL MENTION THE
RISK FOR SEVERE STORMS DURING THIS TIME. /CME/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 35 50 28 62 / 18 3 1 0
MERIDIAN 35 51 26 60 / 18 6 1 1
VICKSBURG 34 52 27 64 / 17 2 0 0
HATTIESBURG 40 54 27 61 / 19 2 0 0
NATCHEZ 35 53 30 64 / 21 1 0 0
GREENVILLE 30 47 30 60 / 7 8 1 0
GREENWOOD 31 46 28 62 / 9 9 2 1
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
22/BB/CME
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
529 PM CST Fri Feb 15 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Short Range (Tonight through Sunday)...
Main weather concern for this period centers on the overnight period
but confined to only the western third of the CWA. One last
vorticity max/shortwave diving down the backside of a retreating
broad upper trough will drop south-southeast across eastern NE
passing just west of the MO/KS state line overnight. Satellite
imagery and radar returns suggest two vorticity maxima...one moving
into northeast NE and a second west of BIE. Features are best seen
on NAM h7 prog. Scattered snow showers a bit more widespread than
shown by NAM output while RAP looks too generous on qpf. Prefer
blending the two model outputs which results in higher pops and
expanding snow shield a bit more east. Moderately high liquid/snow
ratios show potential for a narrow swath of 1+ inches of snow over
the far western counties. Given the expected scattered coverage of
the snow prefer keeping pops under the likely category for now. Snow
will have exited the southwestern CWA by Saturday morning with
clearing from north to south.
Saturday will bring the start of a welcome warmup over the Plains
which will quickly spread east...reaching into the western counties
by the afternoon hours. A band of dense mid level clouds will spread
from west to east Saturday night and herald the arrival of the
deepening warm air advection zone. Still expecting a significant
warmup on Sunday although there may be a tighter west to east
gradient due as boundary layer winds take on a south-southeast
direction which will limit the degree of warming further east.
MJ
Medium Range (Monday through Friday)...
Next week continues to look very active, with two systems moving
through the Plains on Monday night and again from Wednesday night
through early Friday. The primary focus will be the significant
system for Wednesday night through Thursday night, which has the
potential to be a fairly major winter storm if the current track
pans out.
On Monday, a deep longwave trough will dive through the Central
Plains, driving a surface cold front through the CWA during the
daylight hours. A broad area of scattered rain showers will be
possible along and ahead of the front, but amounts will be light as
moisture return into the Plains will be quite limited. A brief mix
with snow may be possible along our eastern border if any light
precipitation can linger behind the surface boundary, but no snow
accumulation is expected.
By Wednesday night, a deep upper low will begin to eject out of the
four corners region. As it moves eastward into the southern Plains,
strong southerly flow will draw Gulf moisture into the system, which
will combine with the existing Pacific moisture and enhance
precipitation coverage and intensity as the system begins to lift
northeast. All model solutions bring the elevated warm front into at
least the southeastern two thirds of the CWA by Thursday morning but
keep cold air lingering at the surface over almost the entirety of
the area, indicating a potential for freezing rain in those areas.
Since this is a deviation from previous forecasts, have started out
with a slight chance for freezing rain on top of the primary
rain/snow mix, but the probability for ice may need to be heightened
if future forecasts look similar. As cold air wraps in behind the
850mb low, precipitation should change to all snow from west to east
during the day on Thursday, becoming all snow and lifting out of the
area after 00z Friday. Very preliminary snowfall totals range from
more than 6 inches across the northern third of the forecast area
where precipitation type is likely to be snow during the majority of
the event, to 2-3 inches in west central and eastern parts of the
CWA, then tapering to less than 2 inches in the far southwest where
rain or freezing rain will be the predominant precipitation type
during the majority of the event.
With the consistency of model solutions, both temporally and between
different model configurations, the overall potential for a winter
storm is increasing. However, precipitation types and snowfall
amounts are still somewhat uncertain and will need to be further
refined, especially as this system heads onshore early next week.
Laflin
&&
.AVIATION...
For the 00Z TAFs...Area of snow showers over southeast NE is tracking
directly toward the STJ/MCI/MKC corridor and will affect all 3
terminals between 02Z and 06Z. The wave producing this activity is
more robust than the one last night, and therefore expect it to hold
together long enough to produce occl MVFR or IFR restrictions
through this 4 hour period with some potential light accumulations on
runways.
Hawblitzel
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
334 PM CST THU FEB 14 2013
.SHORT TERM...
ISSUED AT 333 PM CST THU FEB 14 2013
(TONIGHT)
SECONDARY COLD FRONT IS EXPECTED TO MOVE THROUGH THE CWFA BY AROUND MIDNIGHT.
ALOFT...A FAIRLY STRONG 500-HPA SHORTWAVE TROUGH WILL PROVIDE FORCING FOR
ASCENT AND HELP TO PRODUCE SOME LIGHT PRECIPITATION FOR CENTRAL AND NORTHERN
SECTIONS OF THE AREA. NWP GUIDANCE HAVE NOT EXACTLY BEEN CONSISTENT WITH
PLACEMENT OF QPF AXIS...INCLUDING HI-RES SHORT-TERM MODELS SUCH AS THE
RAP/HRRR. THEREFORE...HAVE ELECTED TO KEEP CHANCE POPS IN AREAS WHERE BEST
MID/UPPER LEVEL FORCING WILL BE LOCATED. OVERALL...STILL LOOKS LIKE A LIGHT
QPF EVENT WITH A RAIN/SNOW MIX INITIALLY CHANGING OVER TO SNOW AS THE BOUNDARY
LAYER COOLS SUFFICIENTLY. ACCUMULATIONS OF SNOWFALL ARE LIKELY TO BE ON THE
ORDER OF A DUSTING TO A QUARTER OF AN INCH...THOUGH THESE NW FLOW "SYSTEMS"
THIS WINTER HAVE NOT EXACTLY BEEN WELL BEHAVED.
GOSSELIN
&&
.LONG TERM...
ISSUED AT 333 PM CST THU FEB 14 2013
(FRIDAY THROUGH SUNDAY)
THE TAIL END OF THE SHORTWAVE SHOULD BE THROUGH MOST OF THE AREA BY
18Z THURSDAY. WILL KEEP SCATTERED FLURRIES GOING THROUGH THE
MORNING HOURS UNTIL THE LAST OF THE ENERGY CLEARS THE AREA.
CERTAINLY NOT EXPECTING ANY ADDITIONAL ACCUMULATION AS WE WILL BE
WELL INTO COLD/DRY ADVECTION THROUGH THE LOWEST 10,000FT OF THE
ATMOSPHERE AFTER 12Z. A COLD DRY AIRMASS DROPS ACROSS THE AREA AS
ANOTHER SHORTWAVE DIPS DOWN THE BACKSIDE OF THE OVERALL
TROF...DIGGING AND AMPLIFYING THE LONGWAVE INTO THE LOWER
MISSISSIPPI VALLEY ON SATURDAY. NAM KICKS OUT SOME LIGHT QPF
LATE FRIDAY NIGHT/EARLY SATURDAY MORNING AS THE SHORTWAVE RIPPLES
BY...BUT THE GFS IS DRY AND THE LOCAL WRF MODEL KEEPS THE PRECIP OUT
OF OUR AREA SO HAVE KEPT FORECAST DRY AT THIS TIME. THE AMPLIFIED
LONGWAVE MOVES EAST SATURDAY NIGHT ALLOWING UPPER LEVEL RIDGING AND
WARMER TEMPERATURES TO BUILD BACK INTO MISSOURI AND ILLINOIS ON
SUNDAY. MOS GUIDANCE LOOKS VERY REASONABLE THROUGH THE PERIOD...SO
HAVE USED A BLEND OF THE PREVIOUS FORECAST AND MOS FOR TEMPERATURES
THROUGH SUNDAY.
(MONDAY THROUGH THURSDAY)
ANOTHER LONGWAVE TROF DEEPENS ACROSS THE ROCKY MOUNTAINS SUNDAY
NIGHT INTO MONDAY. THIS WILL FORCE LEE-SIDE CYCLOGENESIS
MONDAY...BUT JUST AS THE UPPER SYSTEM ISN`T A TIGHTLY COMPACTED
SHORTWAVE...THE SURFACE SYSTEM WILL LIKEWISE BE AN ELONGATED TROF
STRETCHING FROM SOUTHERN ONTARIO ALL THE WAY TO TEXAS. PLENTY OF
MOISTURE CONVERGENCE IN THE WARM ADVECTION AHEAD OF THE TROF MONDAY
SO HAVE INCREASED POPS TO LIKELY. AS THE SYSTEM WINDS UP OVER THE
GREAT LAKES ON MONDAY NIGHT AND COLD ADVECTION REALLY RAMPS UP OVER
THE AREA...THE RAIN MAY END AS A LITTLE LIGHT SNOW.
TUESDAY AND WEDNESDAY LOOK PRETTY TRANQUIL AHEAD OF THE NEXT SYSTEM
WITH SEASONABLY COOL TEMPERATURES...BUT THURSDAY LOOKS PRETTY
INTERESTING. MEDIUM RANGE GUIDANCE IS REMARKABLY SIMILAR ON
THURSDAY WITH A VERY STRONG SHORTWAVE MOVING OFF THE
ROCKIES...GENERATING A CLOSED LOW THROUGH MOST OF THE DEPTH OF THE
TROPOSPHERE. BOTH THE GFS AND ECMWF HAVE THE SURFACE LOW GENERALLY
BETWEEN WICHITA AND TOPEKA...WHICH IS PRETTY DARN GOOD AGREEMENT
THIS FAR OUT. RIGHT NOW...THE MOST LIKELY PRECIPITATION TYPE ACROSS
THE AREA LOOKS LIKE A WET SLOPPY RAIN/SNOW MIX AS WE`LL BE ON THE
NORTHEAST SIDE OF THE STORM...STILL IN THE COLD SECTOR. HOWEVER
THIS COULD...AND LIKELY WILL CHANGE ABOUT A DOZEN TIMES BETWEEN NOW
AND THEN.
CARNEY
&&
.AVIATION...
ISSUED AT 1138 AM CST THU FEB 14 2013
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS
UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH
THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST
TO HAVE ALMOST NO IMPACT OTHER THAN WIND SHIFT TO THE WEST-
NORTHWEST. DROPPED GUSTS AT TAF SITES WITH EXCEPTION OF KUIN AS
HIGHER WINDS ALOFT WEAKEN WITH TIME. UPSTREAM OBSERVATIONS ALSO
SUPPORT A BIT WEAKER WINDS AND WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH
LEVEL CLOUDINESS WILL STREAM IN THIS AFTERNOON FROM WEST TO EAST
IN WNW FLOW ALOFT. MVFR CEILINGS ARE FORECAST TO MOVE
SOUTHEASTWARD WITH TIME AND AFFECT TAF SITES OVERNIGHT AS A SECOND
UPPER-LEVEL IMPULSE BRINGS A REINFORCING SHOT OF COLDER AIR ALONG
WITH A CHANCE OF LIGHT SNOW. BEST CHANCES OF LIGHT SNOW ATTM LOOK
TO BE ORIENTED WEST- EAST ORIENTED NEAR INTERSTATE 70. THIS
SCENARIO IS SUPPORTED BY LAST FEW RUNS OF RAP GUIDANCE WHICH HAS
PERFORMED QUITE WELL THIS WINTER...INCLUDING THE FEB. 2 SURPRISE
SNOW WHICH CAME BENEATH NW FLOW ALOFT AS WELL. LOW CLOUDINESS WILL
SCATTER OUT BY TOMORROW MORNING WITH WINDS VEERING TO THE
NORTHWEST WITH SPEEDS BETWEEN 10 AND 15 MPH.
SPECIFICS FOR KSTL...
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS
UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH
THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST
TO HAVE NO IMPACT OTHER THAN WIND SHIFT TO THE WEST-NORTHWEST.
DROPPED GUSTS AT LAMBERT AS HIGHER WINDS FROM ALOFT WEAKEN WITH
TIME. UPSTREAM OBSERVATIONS ALSO SUPPORT A BIT WEAKER WINDS AND
WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH LEVEL CLOUDINESS WILL
STREAM IN THIS AFTERNOON FROM WEST TO EAST IN WNW FLOW ALOFT. MVFR
CEILINGS ARE FORECAST TO MOVE SOUTHEASTWARD WITH TIME AND AFFECT
TAF SITES OVERNIGHT AS A SECOND UPPER-LEVEL IMPULSE BRINGS A
REINFORCING SHOT OF COLDER AIR ALONG WITH A CHANCE OF LIGHT SNOW.
BEST CHANCES OF LIGHT SNOW ATTM LOOK TO BE ORIENTED WEST-EAST
ORIENTED NEAR INTERSTATE 70. THIS SCENARIO IS SUPPORTED BY LAST
FEW RUNS OF RAP GUIDANCE WHICH HAS PERFORMED QUITE WELL THIS
WINTER...INCLUDING THE FEB. 2 SURPRISE SNOW WHICH CAME BENEATH NW
FLOW ALOFT AS WELL. LOW CLOUDINESS WILL SCATTER OUT BY TOMORROW
MORNING WITH WINDS VEERING TO THE NORTHWEST WITH SPEEDS BETWEEN 10
AND 15 MPH.
GOSSELIN
&&
.PRELIMINARY POINT TEMPS/POPS...
SAINT LOUIS 30 37 22 34 / 30 10 10 5
QUINCY 24 33 17 31 / 30 10 10 5
COLUMBIA 28 37 19 35 / 20 10 10 5
JEFFERSON CITY 29 37 20 35 / 20 10 10 5
SALEM 32 36 21 32 / 30 10 10 5
FARMINGTON 31 39 20 36 / 20 10 10 5
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1147 AM CST THU FEB 14 2013
.SHORT TERM...
ISSUED AT 320 AM CST THU FEB 14 2013
(TODAY)
FIRST IN A SERIES OF COLD FRONTS TO SLIDE THROUGH FORECAST AREA THIS
MORNING WITH SOUTHWEST WINDS VEERING TO THE WEST AND PICKING UP. NOT
A LOT OF CAA WITH THIS INITIAL FRONTAL BOUNDARY AND WITH DECENT
MIXING TO 850 MB...SO SHOULD STILL SEE TEMPS WARM UP TODAY INTO THE
UPPER 40S TO MID 50S. AS FOR THE WINDS...TO INCREASE TO 10 TO 20 MPH
WITH GUSTS NEAR 30 MPH AT TIMES THIS AFTERNOON...ESPECIALLY OVER
NORTHERN PORTIONS OF FORECAST AREA.
BYRD
&&
.LONG TERM...
ISSUED AT 320 AM CST THU FEB 14 2013
(TONIGHT-SUNDAY)
BEEN STRUGGLING ON WHAT TO DO WITH PRECIP POTENTIAL TONIGHT AS
SECONDARY SHORTWAVE DROPS S AND DEEPENS TROF OVER THE CENTRAL U.S.
00Z NAM AND ASSOCIATED OUTPUT SUGGESTS VORT MAX WILL STAY RATHER
WELL-DEFINED AS IT DIVES SE ACROSS THE AREA TONIGHT GENERATING LIGHT
QPF OVER MOST OF THE REGION AND SUGGESTING SOME VERY MINOR SNOW
ACCUMULATIONS. MEANWHILE...WHILE OTHER SOLUTIONS TEND TO FORECAST
MORE OF A BROAD TROF...AND LESSER QPF...SWEEPING ACROSS THE AREA.
NOT CERTAIN WHICH TREND IS MORE CORRECT...BUT AM A LITTLE
CONCERNED THAT ALL SHORT RANGE SOLUTIONS DO INDICATE MID LEVEL
LAPSE RATES GETTING FAIRLY STEEP OVERNIGHT. HAVE DECIDED TO ADD
CHANCE POPS FOR MUCH OF THE AREA...SLOWLY SPREADING FROM N TO S
DURING THE OVERNIGHT HOURS. GIVEN FORECAST SOUNDINGS IT CERTAINLY
POSSIBLE THAT ANY PRECIP WOULD START AS A BIT OF LIGHT RAIN...BUT
IF THERE IS ANY INTENSITY TO THE PRECIP THINK EVAP COOLING WILL
QUICKLY COOL LOW LEVELS ENOUGH TO CHANGE THE RAIN TO SNOW.
THE LEADING EDGE OF THE TRULY COLD AIR WILL ARRIVE LATER
TONIGHT...AND DUE TO ITS LATE ARRIVAL MINS MAY STILL NOT BE TOO
TERRIBLY COLD. HOWEVER...THE TEMPERATURE REBOUND ON FRIDAY SHOULD
NOT BE MORE THAN 10 DEGREES DUE TO THE INTENSITY OF THE COLD
AIR ADVECTION...EVEN WITH A FAIR AMOUNT OF AFTERNOON SUNSHINE.
THE CAA IS FORECAST TO CONTINUE INTO THE START OF THE WEEKEND...AND A
REINFORCING SHOT OF COLD AIR SHOULD ARRIVE FRIDAY NIGHT/SATURDAY
MORNING AS A THIRD SHORTWAVE DIVES INTO THE AREA. WILL HAVE TO
KEEP AN EYE ON THE PRECIP POTENTIAL WITH THIS FEATURE AS THE
TRICKY N/NW FLOW PERSISTS OVER THE CENTRAL CONUS...BUT RIGHT NOW
IT APPEARS MAIN DYNAMICS WOULD BE IMPACTING AREAS WEST OF OUR CWA.
LOWEST TEMPERATURES OF THIS COLD SNAP SHOULD BE ON SATURDAY...WITH
MORNING LOWS IN THE TEENS AND LOWER 20S AND HIGHS IN THE 30-35
DEGREE RANGE.
00Z RUNS CONTINUE TO SUPPORT IDEA THAT UA PATTERN WILL REMAIN QUITE
PROGRESSIVE...TAKING CENTRAL CONUS TROF TO THE EAST COAST BY SUNDAY
WHICH IN TURN WILL ALLOW A RAPID MODERATION IN TEMPERATURES OVER THE
MID MISSISSIPPI VALLEY FOR THE LAST HALF OF THE WEEKEND.
TEMPERATURES SHOULD CLIMB 15 DEGREES OR SO FROM SATURDAY`S
HIGHS...AND RANGE FROM THE MID 40S OVER OUR E IL COUNTIES TO AROUND
50 OVER MID MO.
(MONDAY-WEDNESDAY)
MODEL TO MODEL AND RUN TO RUN AGREEMENT IN BROAD-SCALE SYNOPTIC
FEATURES CONTINUES INTO THE FIRST HALF OF NEXT WEEK...WITH NEXT
STRONG TROF PUSHING ACROSS AREA MONDAY AND MONDAY EVENING WITH
FAIRLY GOOD RAIN POTENTIAL GIVEN MOISTURE ADVECTION INTO AREA AND
STRONG DYNAMICS.
ANOTHER ROUND OF BELOW NORMAL TEMPERATURES IS EXPECTED IN THE WAKE
OF THIS SYSTEM ON TUESDAY AND WEDNESDAY.
TRUETT
&&
.AVIATION...
ISSUED AT 1138 AM CST THU FEB 14 2013
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS
UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH
THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST
TO HAVE ALMOST NO IMPACT OTHER THAN WIND SHIFT TO THE WEST-
NORTHWEST. DROPPED GUSTS AT TAF SITES WITH EXCEPTION OF KUIN AS
HIGHER WINDS ALOFT WEAKEN WITH TIME. UPSTREAM OBSERVATIONS ALSO
SUPPORT A BIT WEAKER WINDS AND WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH
LEVEL CLOUDINESS WILL STREAM IN THIS AFTERNOON FROM WEST TO EAST
IN WNW FLOW ALOFT. MVFR CEILINGS ARE FORECAST TO MOVE
SOUTHEASTWARD WITH TIME AND AFFECT TAF SITES OVERNIGHT AS A SECOND
UPPER-LEVEL IMPULSE BRINGS A REINFORCING SHOT OF COLDER AIR ALONG
WITH A CHANCE OF LIGHT SNOW. BEST CHANCES OF LIGHT SNOW ATTM LOOK
TO BE ORIENTED WEST- EAST ORIENTED NEAR INTERSTATE 70. THIS
SCENARIO IS SUPPORTED BY LAST FEW RUNS OF RAP GUIDANCE WHICH HAS
PERFORMED QUITE WELL THIS WINTER...INCLUDING THE FEB. 2 SURPRISE
SNOW WHICH CAME BENEATH NW FLOW ALOFT AS WELL. LOW CLOUDINESS WILL
SCATTER OUT BY TOMORROW MORNING WITH WINDS VEERING TO THE
NORTHWEST WITH SPEEDS BETWEEN 10 AND 15 MPH.
SPECIFICS FOR KSTL...
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS
UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH
THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST
TO HAVE NO IMPACT OTHER THAN WIND SHIFT TO THE WEST-NORTHWEST.
DROPPED GUSTS AT LAMBERT AS HIGHER WINDS FROM ALOFT WEAKEN WITH
TIME. UPSTREAM OBSERVATIONS ALSO SUPPORT A BIT WEAKER WINDS AND
WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH LEVEL CLOUDINESS WILL
STREAM IN THIS AFTERNOON FROM WEST TO EAST IN WNW FLOW ALOFT. MVFR
CEILINGS ARE FORECAST TO MOVE SOUTHEASTWARD WITH TIME AND AFFECT
TAF SITES OVERNIGHT AS A SECOND UPPER-LEVEL IMPULSE BRINGS A
REINFORCING SHOT OF COLDER AIR ALONG WITH A CHANCE OF LIGHT SNOW.
BEST CHANCES OF LIGHT SNOW ATTM LOOK TO BE ORIENTED WEST-EAST
ORIENTED NEAR INTERSTATE 70. THIS SCENARIO IS SUPPORTED BY LAST
FEW RUNS OF RAP GUIDANCE WHICH HAS PERFORMED QUITE WELL THIS
WINTER...INCLUDING THE FEB. 2 SURPRISE SNOW WHICH CAME BENEATH NW
FLOW ALOFT AS WELL. LOW CLOUDINESS WILL SCATTER OUT BY TOMORROW
MORNING WITH WINDS VEERING TO THE NORTHWEST WITH SPEEDS BETWEEN 10
AND 15 MPH.
GOSSELIN
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BILLINGS MT
856 PM MST FRI FEB 15 2013
.SHORT TERM...VALID FOR SAT AND SUN...
WE INCREASED FORECAST LOWS BY A COUPLE DEGREES TONIGHT ACROSS MUCH
OF THE AREA...BUT THAT WAS REALLY THE ONLY ADJUSTMENT OF NOTE WITH
OUR EVENING UPDATE. MID-LEVEL WARM AIR ADVECTION IS BEGINNING THIS
EVENING AS A 500-HPA RIDGE STARTS BUILDING IN FROM THE WEST. THERE
HAVE BEEN SOME ECHOES ON RADAR IMAGERY OVER FAR EASTERN MT TIED TO
WEAK FORCING ON ISENTROPIC SURFACES ALONG THE MID-LEVEL WARM FRONT
THE LAST FEW HOURS...BUT AS OF 0345 UTC THERE HAVE BEEN NO REPORTS
OF PRECIPITATION AT THE GROUND. EVEN SO...WE DECIDED TO MAINTAIN A
SLIGHT CHANCE OF SNOW FOR BAKER THROUGH 06 UTC BASED ON THE 00 UTC
NAM AND RECENT RAP SIMULATIONS. TEMPERATURES HAVE ONLY DROPPED OFF
SLOWLY IN MANY AREAS THIS EVENING THANKS TO 1/ MID- AND HIGH-LEVEL
CLOUDS...AND 2/ INCREASING WINDS ACROSS SOUTH CENTRAL MT WHILE LEE
TROUGHING BECOMES ESTABLISHED. BASED ON THAT...WE UTILIZED THE NEW
00 UTC MET AND RECENT LAMP MOS TO RAISE LOWS A FEW DEGREES IN MANY
AREAS.
FINALLY...WINDS ARE ON THE INCREASE AT LIVINGSTON...AND THE 00 UTC
NAM STILL CALLS FOR A PRESSURE GRADIENT OF AT LEAST 15 HPA BETWEEN
IDAHO FALLS AND LEWISTOWN BY SAT MORNING. THUS...OUR WIND ADVISORY
LOOKS ON TRACK. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
NO MAJOR CHANGES TO THE GOING FORECAST THIS AFTERNOON. UPPER TROF
PUSHES THROUGH THE AREA ON MONDAY EXITING MONDAY NIGHT. CURRENT
LOW POPS LOOK OK FOR SUNDAY NIGHT...BUT MAY NEED TO BUMP UP
DAYTIME POPS MONDAY IF LATEST SOLUTION PERSIST. TEMPERATURES
MONDAY WILL BE BELOW SEASONAL LEVELS...MAINLY IN THE 30S. TUESDAY
BRINGS AN UPPER RIDGE TO THE AREA FOR MAINLY DRY
CONDITIONS...THOUGH A BACKDOOR COLD FRONT COULD BRING SOME LIGHT
SNOW/FLURRIES TO EASTERN ZONES.
STRONG STORM SYSTEM TAKING SHAPE FOR WEDNESDAY INTO NEXT WEEKEND.
SOUTHERLY DIFFLUENT FLOW WILL DEVELOP ON WEDNESDAY OVER THE AREA
ON THE FRONT SIDE OF THE TROF. UPPER LOW THEN PUSHES OUT OF
CALIFORNIA ON A NORTHEASTERLY TRAJECTORY INTO THE CENTRAL PLAINS
BY THURSDAY...THEN PINWHEELS INTO THE NORTHERN PLAINS ON FRIDAY.
MODELS DISAGREEING ON THE TRACK WITH THIS LOW...WHICH IS NOT
UNCOMMON 5 TO 7 DAYS OUT. GFS GOES WELL SOUTH OF THE FOUR CORNERS
WITH THE UPPER LOW BEFORE KICKING NORTH...WHILE THE ECMWF TAKES A
PATH FROM LAS VEGAS TO GRAND JUNCTION. THE MORE NORTHERLY PATH
WOULD KEEP MORE ENERGY AND MOISTURE ACROSS SOUTHERN MONTANA THAN
THE FURTHER SOUTH SOLUTION. CURRENTLY HAVE TEMPERATURES WELL BELOW
AVERAGE IN THE FORECAST FOR THIS PERIOD WHICH SEEMS REASONABLE
GIVEN THE DEEP TROF OVER THE AREA. BROADBRUSH CHANCE TYPE
PRECIPITATION CHANCES SEEM REASONABLE AS WELL. THIS TYPE OF SYSTEM
CLIMATOLOGICALLY HAS A GOOD CHANCE TO PRODUCE SIGNIFICANT
PRECIPITATION OVER THE AREA...ESPECIALLY SOUTHEAST MONTANA AND
WILL BE WATCHED CLOSELY AS IT EVOLVES IN THE MODELS OVER THE NEXT
FEW DAYS. CHAMBERS
&&
.AVIATION...
VFR CONDITIONS EXPECTED TONIGHT. WINDS OVER WESTERN FOOTHILLS
LOCATIONS WILL INCREASE OVERNIGHT WITH GUSTS AROUND 40KTS
EXPECTED. WIND GUSTS WILL INCREASE TO AROUND 50KTS BY SUNRISE IN
THE LIVINGSTON TO BIG TIMBER TO NYE TRIANGLE. LOW LEVEL WIND SHEAR
WILL EXIST OVERNIGHT FOR KMLS AND KSHR TAF LOCATIONS WITH WEST TO
NORTHWEST WINDS AROUND 35KTS JUST OFF THE SURFACE. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 029/052 030/044 021/032 014/028 013/024 010/027 014/033
00/N 16/W 42/J 11/B 34/S 42/S 22/S
LVM 035/049 030/040 017/033 013/033 016/026 011/032 016/035
00/N 36/J 43/J 02/J 34/S 32/S 22/S
HDN 024/048 025/041 019/030 009/028 013/026 006/027 008/032
00/U 16/J 52/J 11/B 24/S 42/S 22/S
MLS 028/049 033/041 019/026 007/026 007/023 006/022 009/027
10/U 15/W 62/J 11/B 13/S 32/S 22/S
4BQ 025/046 027/041 019/027 008/027 011/026 007/020 008/028
10/U 03/J 62/J 11/B 14/S 42/S 22/S
BHK 025/045 029/041 017/021 003/020 005/017 003/014 003/024
20/B 04/J 62/J 11/U 13/S 32/S 22/S
SHR 019/045 020/038 017/029 008/030 015/027 005/024 007/033
00/U 04/J 63/J 11/B 25/S 52/S 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 9 AM MST
SUNDAY FOR ZONES 65-66.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1100 PM MST Wed Feb 13 2013
.DISCUSSION...
Update forthcoming. Cold front has pushed through the Great Falls
area and areas of snow have developed behind the front. Radar
indicating a couple of bands of snow located just north of Great
Falls and moving northwest to southeast. This band is slowly sagging
south. RUC analysis indicates heaviest snow should fall between now
and midnight with snow tapering off after that. Have raised pops and
snow amounts for portions of North Central Montana. Emanuel
&&
.AVIATION...
Updated 0600Z.
A moist northwest flow aloft will continue over Montana through
Thursday. Scattered showers can be expected around terrain across
Central Montana through about 12z. Activity diminishes early morning
over most of Montana before skies clear out a bit through the middle
of the day. Expect mid and upper clouds to increase later afternoon
Thursday before another possible round of evening showers.
&&
.PREV DISCUSSION...Issued 248 PM MST Wed Feb 13 2013
Wednesday through Friday...Convective activity continues to
develop and move across Central and North Central Montana with
showers slowly moving southward into the Mountains of Southwest
Montana. Convective activity should continue into the evening
hours but diminish significantly by sunset when daytime heating no
longer drives the thermal activity. Temperatures decrease back
towards seasonal averages tonight behind the cold front. High
temperatures will be limited as the cool air mass slowly
moderates over the next 24 hours. Some moisture aloft will allow
for the possibility of snow showers over the higher terrain
through Thursday night...however no significant accumulations are
expected...especially at the lower elevation. An upper level ridge
will begin to move into the region by Friday and allow for drier
and warmer conditions to again develop throughout the day...with
temperatures rising back above seasonal averages. Suk
Friday night through Wednesday night...Good consistency continues
among the models for this period. An upper level ridge of high
pressure building into Montana Friday night and Saturday will keep
the area mostly dry and quite mild (10 to 15 degrees above normal -
with highs on Saturday reaching into the 40s to lower 50s). A
shortwave trough will flatten the ridge as it moves into the area
from the Pacific Northwest coast on Saturday, bringing a chance of
showers to the Rocky Mountain Front and increasing westerly
downslope winds to the remainder of the area. This shortwave will
then move southeast through the area Saturday night into Sunday with
an associated Canadian cold front. The chance for precipitation will
increase Saturday night, while models continue to bring widespread
light snow to the area on Sunday. Have therefore increased the
chance for precipitation a bit more through these periods.
Temperatures will be quite cool with the frontal passage on Sunday,
as highs will only reach into the upper 20s to mid 30s most areas.
Forecast snowfall amounts are fairly light at this time (with most
lower elevations only forecast to receive an inch or 2 of snow).
However, this situation will continue to be monitored for potential
winter weather highlights, as the warm-up prior to the snow may warm
pavement enough that initially melting snow may refreeze with the
passage of the cold front, causing icy roadways. This may become a
situation similar to that from this past weekend. An upper level
ridge of high pressure will then follow this system into the state
Sunday night through Monday night, allowing temperatures to warm
back closer to normal with a decreasing chance of snow. A deep
upper level trough of low pressure will then move across the western
CONUS Tuesday night through Wednesday. The trough is forecast to
split somewhat, with the southern portion taking the bulk of the
energy south of the area. Despite this, a low level easterly flow
may bring enough moisture into the southern half of the state to
allow a good chance of snow to develop across central/southwest
Montana. Coulston
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 21 35 21 42 / 100 10 10 10
CTB 16 34 21 41 / 30 10 10 10
HLN 25 35 22 40 / 40 30 20 10
BZN 20 31 16 36 / 60 40 30 10
WEY 10 24 6 29 / 60 30 40 10
DLN 20 32 17 37 / 30 30 20 10
HVR 10 27 9 31 / 20 10 10 10
LWT 16 28 14 34 / 100 30 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
910 PM MST Wed Feb 13 2013
.DISCUSSION...
Update forthcoming. Cold front has pushed through the Great Falls
area and areas of snow have developed behind the front. Radar
indicating a couple of bands of snow located just north of Great
Falls and moving northwest to southeast. This band is slowly sagging
south. RUC analysis indicates heaviest snow should fall between now
and midnight with snow tapering off after that. Have raised pops and
snow amounts for portions of North Central Montana. Emanuel
&&
.AVIATION...
Updated 0040Z.
A moist northwest flow aloft will continue over Montana through
Thursday. Scattered showers can be expected around terrain across
Central Montana. Activity diminishes overnight but small areas of
light snow may persist across some valley locations in the forecast
area. Expect local MVFR conditions and mountain obscurations through
12Z in these locations. Precipitation expected to mostly end with
cloud cover decreasing from the north after 12Z.
&&
.PREV DISCUSSION...Issued 248 PM MST Wed Feb 13 2013
Wednesday through Friday...Convective activity continues to
develop and move across Central and North Central Montana with
showers slowly moving southward into the Mountains of Southwest
Montana. Convective activity should continue into the evening
hours but diminish significantly by sunset when daytime heating no
longer drives the thermal activity. Temperatures decrease back
towards seasonal averages tonight behind the cold front. High
temperatures will be limited as the cool air mass slowly
moderates over the next 24 hours. Some moisture aloft will allow
for the possibility of snow showers over the higher terrain
through Thursday night...however no significant accumulations are
expected...especially at the lower elevation. An upper level ridge
will begin to move into the region by Friday and allow for drier
and warmer conditions to again develop throughout the day...with
temperatures rising back above seasonal averages. Suk
Friday night through Wednesday night...Good consistency continues
among the models for this period. An upper level ridge of high
pressure building into Montana Friday night and Saturday will keep
the area mostly dry and quite mild (10 to 15 degrees above normal -
with highs on Saturday reaching into the 40s to lower 50s). A
shortwave trough will flatten the ridge as it moves into the area
from the Pacific Northwest coast on Saturday, bringing a chance of
showers to the Rocky Mountain Front and increasing westerly
downslope winds to the remainder of the area. This shortwave will
then move southeast through the area Saturday night into Sunday with
an associated Canadian cold front. The chance for precipitation will
increase Saturday night, while models continue to bring widespread
light snow to the area on Sunday. Have therefore increased the
chance for precipitation a bit more through these periods.
Temperatures will be quite cool with the frontal passage on Sunday,
as highs will only reach into the upper 20s to mid 30s most areas.
Forecast snowfall amounts are fairly light at this time (with most
lower elevations only forecast to receive an inch or 2 of snow).
However, this situation will continue to be monitored for potential
winter weather highlights, as the warm-up prior to the snow may warm
pavement enough that initially melting snow may refreeze with the
passage of the cold front, causing icy roadways. This may become a
situation similar to that from this past weekend. An upper level
ridge of high pressure will then follow this system into the state
Sunday night through Monday night, allowing temperatures to warm
back closer to normal with a decreasing chance of snow. A deep
upper level trough of low pressure will then move across the western
CONUS Tuesday night through Wednesday. The trough is forecast to
split somewhat, with the southern portion taking the bulk of the
energy south of the area. Despite this, a low level easterly flow
may bring enough moisture into the southern half of the state to
allow a good chance of snow to develop across central/southwest
Montana. Coulston
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 21 35 21 42 / 100 10 10 10
CTB 16 34 21 41 / 30 10 10 10
HLN 25 35 22 40 / 40 30 20 10
BZN 20 31 16 36 / 60 40 30 10
WEY 10 24 6 29 / 60 30 40 10
DLN 20 32 17 37 / 30 30 20 10
HVR 10 27 9 31 / 20 10 10 10
LWT 16 28 14 34 / 100 30 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1142 AM CST THU FEB 14 2013
.UPDATE...
UPDATED EARLIER TO TEMPS TO RAISE A COUPLE OF DEGREES FOR TODAY
AS TEMPS ACROSS THE NORTH STAYED WARM OVERNIGHT AND WERE ALREADY
NEAR HIGHS. DISTURBANCE WILL CONTINUE TO PUSH SOUTH FROM S DAKOTA
INTO NEBRASKA THIS AFTERNOON...WHILE ANOTHER DISTURBANCE IS
EXITING SW NEBRASKA INTO CO/KS. WITH TEMPS GENERALLY IN THE MID
30S AND COLD AIR WITH THE DISTURBANCES AND SOME WEAK
LIFT...EXPECTING MAINLY LIGHT SNOW SHOWERS OR FLURRIES. WIND
ADVISORY CONTINUES FOR THE DAY...WITH WINDS STARTING TO
INCREASE...WITH SEVERAL SITES APPROACHING ADV CRITERIA. LIKELY A
MARGINAL EVENT...BUT STILL BE WILL A WINDY AFTERNOON.
&&
.AVIATION...
MVFR CIGS ASSOCIATED WITH A DISTURBANCE ACROSS S DAKOTA WILL
SPREAD INTO NRN NEB...AND THE KVTN TERMINAL...THIS AFTERNOON.
ALSO COULD SEE SOME LIGHT SNOW OR FLURRIES...AND WILL MENTION WITH
A TEMPO GROUP. SW NEB...AND THE KLBF TERMINAL MAY SEE SOME ISOLD
FLURRIES...HOWEVER COVERAGE DOES NOT WARRANT MENTION IN THE TAF AT
THIS TIME. WILL CONTINUE TO MONITOR RADAR AND MAY AMEND FOR A
BRIEF PERIOD OF LIGHT SNOW...ALTHOUGH DURATION SHOULD BE SHORT.
CIGS EXPECTED TO REMAIN IN THE VFR CATEGORY FOR KLBF. WINDS THIS
AFTERNOON WILL INCREASE TO 20 TO 30 KTS WITH HIGHER GUSTS. WINDS
DIMINISH THIS EVENING BECOMING LESS THAN 10KTS OVERNIGHT.
TOMORROW SOME LINGER FLURRIES/MVFR CIGS ACROSS THE AREA...HOWEVER
NOT EXPECTING THE STRONG WINDS.
&&
.PREV DISCUSSION... /ISSUED 633 AM CST THU FEB 14 2013/
UPDATE...
DISCUSSION...
NO MAJOR CHANGES TO THIS UPDATE. 06Z NAM IS A BIT DRIER WITH QPF
AMOUNTS. SHSN CONVERAGE IS ABOUT THE SAME. LESS THAN AN INCH OF
SNOW IS EXPECTED.
PREV DISCUSSION... /ISSUED 328 AM CST THU FEB 14 2013/
DISCUSSION...
NEAR TERM...TODAY AND TONIGHT.
SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE
PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD
REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT
THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT
STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH.
TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE.
THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF
GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT.
NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY.
WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE
UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE
HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD
SIGNALING A REINFORCING COLD FRONT FOR FRIDAY.
SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY.
BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL
REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING
SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER
JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP
WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND
FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY
DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY
NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH
HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN
PANHANDLE.
LONG TERM...12Z SUNDAY AND BEYOND.
SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE
ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO
THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER
THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON
SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL
HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER
THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S
SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH
THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR
PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES
COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO
MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR
BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT.
ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD
BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY.
SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT
BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE
MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE
CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE
DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED
TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER
PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE
POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED
YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING FOR
NEZ004>010-022>029-035>038-056>059-069>071-094.
&&
$$
UPDATE/AVIATION....MASEK
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1116 AM CST THU FEB 14 2013
.AVIATION...18Z TAF. WINDS WILL INCREASE A LITTLE YET THIS
AFTERNOON AND THEN DIMINISH AS THE SUN GOES DOWN THIS EVENING.
THERE ARE SOME MID AND LOWER CLOUDS TO THE NORTHWEST THAT WILL BE
MOVING INTO THE KGRI TERMINAL AREA THIS AFTERNOON...BUT THE
CEILINGS WILL REMAIN VFR THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 529 AM CST THU FEB 14 2013/
SHORT TERM...ALTHOUGH NO TRULY HIGH-IMPACT WEATHER IS EXPECTED
DURING THE NEXT 72 HOURS...THINGS START OFF WITH A SOMEWHAT MARGINAL
WIND ADVISORY EVENT TODAY...FOLLOWED BY PESKY HARD-TO-PIN-DOWN
FLURRY/BRIEF SNOW SHOWER CHANCES FROM THIS AFTERNOON THROUGH
FRIDAY EVENING. ALTHOUGH THE VAST MAJORITY OF THE CWA IS UNLIKELY
TO SEE ACCUMULATING SNOW...A LIGHT DUSTING HERE OR THERE IS NOT
OUT OF THE QUESTION ESPECIALLY FRIDAY AFTERNOON/EVENING.
10Z OBJECTIVE CENTRAL PLAINS SURFACE ANALYSIS REVEALS A SUBTLE
SURFACE TROUGH FROM EASTERN-SOUTHERN KANSAS...TRAILING SOUTHWEST
FROM A 1001MB LOW IN WISCONSIN. A BROAD WEST-NORTHWEST SURFACE
WIND REGIME WAS FIRMLY IN PLACE ACROSS THE CWA...WITH SUSTAINED
SPEEDS GENERALLY 5-15 MPH. THESE STEADY BREEZES ARE RESULTING IN
AT LEAST A SLIGHTLY-WARMER-THAN-EXPECTED NIGHT...WITH OVERNIGHT
LOWS IN MOST AREAS LIKELY BOTTOMING OUT BETWEEN 27-31 DEGREES. TO
THE NORTH...A SOMEWHAT ILL-DEFINED EAST-WEST COLD FRONT IS ALIGNED
ACROSS SOUTH DAKOTA...WITH THIS BOUNDARY EXPECTED TO VERY SLOWLY
BLEED SOUTHWARD ACROSS THE LOCAL AREA AS THE DAY WEARS ON.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA IS
HIGHLIGHTED BY INCREASINGLY ACTIVE NORTHWEST FLOW...AS JUST IN THE
PAST 12 HOURS A PAIR OF LOW AMPLITUDE CLIPPER SHORTWAVE TROUGHS
HAVE TRACKED ALONG A CORRIDOR FROM THE DAKOTAS TOWARD IA. 11-3.9
MICRON SATELLITE IMAGERY SHOWS RELATIVELY CLEAR SKIES STEADILY
GIVING WAY TO INCREASING HIGH CLOUD COVER FROM THE WEST.
MEANWHILE...A SMALL BATCH OF MID LEVEL CLOUDS THAT BROUGHT SOME
RATHER UNEXPECTED BRIEF SPRINKLES TO PARTS OF THE CWA LAST EVENING
HAS MOVED WELL OFF TO THE SOUTHEAST.
TODAY...THE MAIN FOCUS CONTINUES TO BE ON INCREASING NORTHWEST
WINDS...ALTHOUGH WILL STATE UP FRONT THAT THE INTENSITY/DURATION
OF THE STRONGEST WINDS HAS NOW TRENDED DOWNWARD A BIT OVER THE
PAST FEW MODEL RUNS...SO THIS WILL LIKELY BE A SOMEWHAT MARGINAL
WIND ADVISORY EVENT. WINDS WILL NOT START THE DAY ALL THAT
STRONG...AS IT WILL BE AT LEAST LATE MORNING/EARLY AFTERNOON
BEFORE INCREASING PRESSURE RISES AND DEEPENING MIXING BEHIND THE
INITIAL PASSING COLD FRONT RAMPS SPEEDS UP. ALOFT...THIS
INCREASING SURGE OF NORTHWEST WINDS WILL BE DRIVEN BY LOW
AMPLITUDE SHORTWAVE TROUGH DROPPING SOUTH OF SD INTO NEB/IA. HAVE
MADE NO CHANGES WHATSOEVER TO THE WIND ADVISORY ITSELF...STARTING
AT 11 AM AND ENDING AT 6 PM...WITH THE OVERALL BEST TIME FRAME FOR
SUSTAINED SPEEDS NEARING/MEETING 30 MPH WITH GUSTS 40 TO POSSIBLY
45 MPH CENTERED DURING THE MID-AFTERNOON. FARTHER SOUTH IN OUR KS
ZONES...AM GENERALLY EXPECTING SUSTAINED SPEEDS TO TOP OUT CLOSE
TO 25 MPH...THUS FALLING ABOUT 5 MPH SHORT OF ADVISORY CRITERIA SO
NOT ANTICIPATING ANY SOUTHWARD EXPANSION AT THIS TIME. HOURLY TEMP
TRENDS WILL BE TRICKY TODAY WITH A FAIRLY RAPID INITIAL RISE THEN
FOLLOWED BY A SLOW-BUT-STEADY FALL AS THE AFTERNOON WEARS ON AND
COLD AIR ADVECTION TAKES HOLD. HAVE FOLLOWED THE 06Z RAP SOLUTION
FAIRLY CLOSELY...WHICH ACTUALLY RESULTED IN ABOUT A 4 DEGREE
UPWARD BUMP TO HIGHS WITH MOST OF SOUTH CENTRAL NEBRASKA NOW
EXPECTED TO AT LEAST BRIEFLY TOUCH THE MID IF NOT UPPER 40S EXCEPT
COOLER FAR NORTH...AND KS ZONES RIGHT AROUND 50. THE ONLY CAVEAT HERE
IS WHETHER INCOMING MID/HIGH CLOUDS ARE THICK ENOUGH TO TEMPER
THINGS A BIT. PRECIPITATION WISE...KEPT ALL MENTION OUT OF THE
MORNING HOURS...BEFORE BRINGING IN NON-MEASURABLE CHANCES FOR
FLURRIES AND/OR SPRINKLES DURING THE AFTERNOON IN RESPONSE TO THE
INCOMING MID LEVEL SHORTWAVE TROUGH AND INCREASING UPPER JET
DYNAMICS. RAW MODEL QPF FIELDS CONTINUE TO BE ALL OVER THE
PLACE...AND ALTHOUGH THE MAJORITY OF THE CWA MAY NOT SEE A SINGLE
RAIN DROP OR SNOWFLAKE BEFORE SUNSET...IT SEEMS THE MOST FAVORED AREAS
WOULD BE NORTH OF NEBRASKA HWY 92 AND ALSO WITHIN THE SOUTHWEST
1/4 OF THE CWA.
THIS EVENING/TONIGHT...ALTHOUGH IT WILL REMAIN QUITE BREEZY EARLY
ON THIS EVENING...HAVE FAIRLY HIGH CONFIDENCE THAT THE WIND SPEEDS
WILL SAFELY FALL BELOW ADVISORY CRITERIA BY THE CURRENT EXPIRATION
TIME OF 6 PM...WITH SUSTAINED SPEEDS THEN STEADILY TRENDING DOWN
THROUGH THE REMAINDER OF THE NIGHT AS SURFACE HIGH PRESSURE SETTLES
IN FROM THE NORTHWEST. IN FACT AFTER MIDNIGHT...ONLY LOOKING AT SPEEDS
AROUND 10 MPH MOST AREAS. ALTHOUGH THE VAST MAJORITY OF THE CWA
WILL LIKELY REMAIN PRECIP-FREE TONIGHT...ITS OFTEN SEEN IN THIS
TYPE OF NORTHWEST FLOW PATTERN THAT EVEN SMALL BANDS/PATCHES OF
MID LEVEL CLOUDS COULD PRODUCE SOME SPORADIC FLURRIES...SO WILL
CONTINUE TO KEEP IT SIMPLE AND BLANKET THE ENTIRE CWA WITH THIS
SLIGHT FLURRY CHANCE. NUDGED DOWN LOW TEMPS GENERALLY 1-2 DEGREES
FROM PREVIOUS GRIDS...WITH MOST AREAS BOTTOMING OUT 15-19 DEGREES
ASSUMING THAT A CLOUD BAND DOESN/T PARK ITSELF SOMEWHERE AND HOLD
THINGS UP A BIT HIGHER.
FRIDAY INTO FRIDAY EVENING WILL HOLD THE BEST POTENTIAL FOR
A MORE WIDESPREAD COVERAGE OF FLURRIES AND POSSIBLY VERY LIGHT
SNOW ACCUMULATIONS IN A FEW AREAS...AS THE FINAL AND LIKELY MOST
VIGOROUS NORTHWEST-FLOW SHORTWAVE TROUGH DROPS SOUTHWARD ACROSS
THE HEART OF THE LOCAL AREA...FOCUSED WITHIN THE EXIT REGION OF A
RATHER STOUT MERIDIONAL UPPER JET OF 120+ KNOTS. ALTHOUGH WILL
KEEP AN OUTSIDE CHANCE OF A FLURRY GOING ON FRIDAY MORNING...HAVE
ADDED A SLIGHT CHANCE MEASURABLE POP TO THE AFTERNOON/EVENING
HOURS AS THE MAIN SHORTWAVE AXIS PASSES OVER. THIS IS LOOKING LIKE
A FAIRLY CLASSIC SETUP FOR QUICK NORTH-TO-SOUTH MOVING BRIEF SNOW
SHOWERS...GIVEN STEEP LOW LEVEL LAPSE RATES AND DEEP MIXING. THIS
SCENARIO IS WELL CAPTURED IN THE REFLECTIVITY PROG OF THE 00Z 4KM
WRF-NMM...WITH HIT AND MISS SNOW SHOWERS BLOSSOMING ACROSS THE
AREA DURING THE DAY BEFORE WEAKENING AND EVENTUALLY MOVING OUT
ALTOGETHER BY MIDNIGHT AS THE BACK EDGE OF THE MID LEVEL TROUGH
AXIS PASSES. THIS WILL BE A SITUATION WHERE SOME AREAS SEE A LIGHT
DUSTING OF SNOW...WHILE OTHERS MISS OUT COMPLETELY...AND AS THESE
MESOSCALE DETAILS BECOME CLEARER ITS POSSIBLE THAT POPS MIGHT BE
RAISED ABOVE THE CURRENT 20 PERCENT IN SOME AREAS. ALTHOUGH
AFTERNOON/EVENING WIND SPEEDS WILL NOT BE AS STRONG AS TODAY...AT
LEAST A FEW HOURS OF SUSTAINED 15-20 MPH SPEEDS IS
EXPECTED...WHICH COULD POSSIBLY RESULT IN LOCALIZED/BRIEF
VISIBILITY RESTRICTIONS UNDER PASSING SNOW SHOWERS...BUT NOT A
WIDESPREAD HAZARD WORTHY OF MENTION IN THE HWO AT THIS TIME.
TEMP-WISE...MADE A VERY SMALL UPWARD NUDGE TO PREVIOUS HIGHS BUT
THIS WILL STILL BE THE COLDEST DAY OF THE WEEK WITH HIGHS IN THE
30S MOST AREAS AND MAYBE ONLY UPPER 20S FAR NORTH. LIGHT WESTERLY
BREEZES LATE FRIDAY NIGHT SHOULD KEEP LOWS FROM TANKING TOO
FAR...BUT STILL DROPPING DOWN BETWEEN 14-18 MOST AREAS.
SATURDAY INTO SATURDAY NIGHT...HAVE RATHER HIGH CONFIDENCE IN A
DRY PERIOD WITH WARMING TEMPERATURES...AS THE BIG PICTURE ALOFT
INVOLVES AN INVADING SHORTWAVE RIDGE IN THE WAKE OF A DEEP
LONGWAVE TROUGH EXITING EASTWARD ACROSS THE EASTERN CONUS. IN THE
LOW LEVELS...WEST-SOUTHWEST BREEZES GENERALLY 10-15 MPH WILL
BRING IN SOME PRETTY STOUT WARM AIR ADVECTION DURING THE
DAY...ALTHOUGH THIS MAY BE TEMPERED SOMEWHAT BY WHAT COULD BE A
FAIRLY SOLID PASSING DECK OF MID CLOUDS. NO MATTER WHAT THOUGH...A
NOTABLE WARM-UP OVER FRIDAY IS IN STORE...AND BASED ON A BLEND OF
THE 00Z NAM/ECMWF RAISED 3-4 DEGREES FROM PREVIOUS FORECAST
ESPECIALLY ACROSS WESTERN COUNTIES...NOW CALLING FOR A RANGE FROM
LOW 40S EAST TO NEAR 50 WEST. SUPPOSE A FEW SPRINKLES FALLING OUT
OF THE AFOREMENTIONED MID DECK IS NOT OUT OF THE QUESTION...BUT
SEEMS UNLIKELY ENOUGH FOR NOW TO OMIT ANY GRID MENTION. SATURDAY
NIGHT...LIGHT WESTERLY BREEZES SHOULD KEEP LOW TEMPS SEVERAL
DEGREES WARMER THAN THE PREVIOUS FEW NIGHTS...AND MADE LITTLE
CHANGE WITH MID 20S MOST AREAS.
LONG TERM...SUNDAY THROUGH WEDNESDAY.
THE LONG TERM WILL CONSIST OF A SERIES OF PROGRESSIVE SHORTWAVE
TROUGHS AND RIDGES OF PACIFIC ORIGIN.
TOOK MORE OF A CONSENSUS APPROACH FOR THE LONG TERM...FAVORING
ENSEMBLE MEANS.
SUNDAY APPEARS THAT IT WILL BE THE MOST MILD DAY AS 850 MB
TEMPERATURES WARM UP NICELY IN ASSOCIATION WITH A PASSING SHORTWAVE
RIDGE. THERE WILL BE INCREASED WARMING JUST AHEAD OF AN APPROACHING
COLD FRONT...WITH SURFACE SOUTHWEST WIND DECREASING AS THE FRONT
APPROACHES...CONDITIONS COULD BECOME DOWNRIGHT SPRING-LIKE FOR THE
AFTERNOON.
COLDER AIR SPILLS IN FOR MONDAY...AND INCREASED WIND SPEEDS FROM THE
NORTH QUITE A BIT FROM ALLBLEND/CONSALL AS A RESULT OF THE HEALTHY
COLD AIR ADVECTION. THE COOL SURFACE HIGH FINALLY MAKES ITS WAY INTO
OUR AREA BY TUESDAY...WHICH SHOULD BE JUST ABOUT THE COOLEST HIGH
FOR THE LONG TERM BEFORE A BIT OF A REBOUND OCCURS FOR WEDNESDAY.
THIS REBOUND OCCURS AHEAD OF A DIGGING MEAN LONG TROUGH OVER THE
ROCKY MOUNTAINS WHICH WILL BE MOVING EAST.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR NEZ039>041-046>049-
060>064-072>077-082>087.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
633 AM CST THU FEB 14 2013
.UPDATE...
.DISCUSSION...
NO MAJOR CHANGES TO THIS UPDATE. 06Z NAM IS A BIT DRIER WITH QPF
AMOUNTS. SHSN CONVERAGE IS ABOUT THE SAME. LESS THAN AN INCH OF
SNOW IS EXPECTED.
&&
.PREV DISCUSSION... /ISSUED 529 AM CST THU FEB 14 2013/
UPDATE...
AVIATION...
SCATTERED MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE
PASSAGE OF AN ARCTIC FRONT CURRENTLY AT 11Z NEAR KSDY. SCATTERED
SNOW SHOWERS AND MVFR WILL ACCOMPANY THE FRONT. MVFR AND ISOLATED SNOW
SHOWERS MAY PERSIST TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR
IS EXPECTED WITH ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY
TODAY. WINDS WILL INCREASE THIS AFTERNOON TO 32025G40KT AND
DECREASE AT SUNSET.
PREV DISCUSSION... /ISSUED 328 AM CST THU FEB 14 2013/
DISCUSSION...
NEAR TERM...TODAY AND TONIGHT.
SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE
PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD
REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT
THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT
STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH.
TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE.
THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF
GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT.
NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY.
WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE
UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE
HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD
SIGNALING A REINFORCING COLD FRONT FOR FRIDAY.
SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY.
BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL
REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING
SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER
JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP
WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND
FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY
DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY
NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH
HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN
PANHANDLE.
LONG TERM...12Z SUNDAY AND BEYOND.
SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE
ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO
THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER
THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON
SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL
HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER
THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S
SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH
THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR
PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES
COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO
MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR
BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT.
ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD
BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY.
SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT
BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE
MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE
CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE
DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED
TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER
PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE
POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED
YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW.
AVIATION...
MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN
ARCTIC FRONT CURRENTLY AT 08Z NEAR KGGW. SCATTERED SNOW SHOWERS WILL
ACCOMPANY THE FRONT. MVFR AND ISOLATES SNOW SHOWERS MAY PERSIST
TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH
ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 10 AM CST /9 AM MST/ THIS MORNING TO 6 PM CST
/5 PM MST/ THIS EVENING FOR NEZ004>010-022>029-035>038-056>059-
069>071-094.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION....CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
540 AM CST THU FEB 14 2013
.AVIATION...12Z KGRI TAF. WIND WILL INCREASE SPEED FOR THIS
MORNING WITH INCREASING HEIGHT RISES BEHIND A COLD FRONT. CEILINGS
COULD BE A BIT TRICKY...YET PROBABLY MAINLY IN THE MID-RANGE FOR
HEIGHT. COULD BE SOME SPRINKLE/FLURRY ACTIVITY...BUT AIR IN LOWER
LEVELS IS QUITE DRY...SO THIS WILL NOT AMOUNT TO A WHOLE
LOT...PERHAPS GIVING A QUICK BIT OF A BURST OF WIND. MODELS
INDICATE THAT THERE COULD BE AT LEAST SOME SCATTERED STRATUS
STICKING AROUND FOR THIS EVENING WITH DECREASING WIND BUT
CONTINUING POSSIBILITY OF FLURRIES...NOT INCLUDED IN THE FORECAST
AS CONFIDENCE IS NOT HIGH FOR THIS OCCURRENCE.
&&
.PREV DISCUSSION... /ISSUED 529 AM CST THU FEB 14 2013/
SHORT TERM...ALTHOUGH NO TRULY HIGH-IMPACT WEATHER IS EXPECTED
DURING THE NEXT 72 HOURS...THINGS START OFF WITH A SOMEWHAT MARGINAL
WIND ADVISORY EVENT TODAY...FOLLOWED BY PESKY HARD-TO-PIN-DOWN
FLURRY/BRIEF SNOW SHOWER CHANCES FROM THIS AFTERNOON THROUGH
FRIDAY EVENING. ALTHOUGH THE VAST MAJORITY OF THE CWA IS UNLIKELY
TO SEE ACCUMULATING SNOW...A LIGHT DUSTING HERE OR THERE IS NOT
OUT OF THE QUESTION ESPECIALLY FRIDAY AFTERNOON/EVENING.
10Z OBJECTIVE CENTRAL PLAINS SURFACE ANALYSIS REVEALS A SUBTLE
SURFACE TROUGH FROM EASTERN-SOUTHERN KANSAS...TRAILING SOUTHWEST
FROM A 1001MB LOW IN WISCONSIN. A BROAD WEST-NORTHWEST SURFACE
WIND REGIME WAS FIRMLY IN PLACE ACROSS THE CWA...WITH SUSTAINED
SPEEDS GENERALLY 5-15 MPH. THESE STEADY BREEZES ARE RESULTING IN
AT LEAST A SLIGHTLY-WARMER-THAN-EXPECTED NIGHT...WITH OVERNIGHT
LOWS IN MOST AREAS LIKELY BOTTOMING OUT BETWEEN 27-31 DEGREES. TO
THE NORTH...A SOMEWHAT ILL-DEFINED EAST-WEST COLD FRONT IS ALIGNED
ACROSS SOUTH DAKOTA...WITH THIS BOUNDARY EXPECTED TO VERY SLOWLY
BLEED SOUTHWARD ACROSS THE LOCAL AREA AS THE DAY WEARS ON.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA IS
HIGHLIGHTED BY INCREASINGLY ACTIVE NORTHWEST FLOW...AS JUST IN THE
PAST 12 HOURS A PAIR OF LOW AMPLITUDE CLIPPER SHORTWAVE TROUGHS
HAVE TRACKED ALONG A CORRIDOR FROM THE DAKOTAS TOWARD IA. 11-3.9
MICRON SATELLITE IMAGERY SHOWS RELATIVELY CLEAR SKIES STEADILY
GIVING WAY TO INCREASING HIGH CLOUD COVER FROM THE WEST.
MEANWHILE...A SMALL BATCH OF MID LEVEL CLOUDS THAT BROUGHT SOME
RATHER UNEXPECTED BRIEF SPRINKLES TO PARTS OF THE CWA LAST EVENING
HAS MOVED WELL OFF TO THE SOUTHEAST.
TODAY...THE MAIN FOCUS CONTINUES TO BE ON INCREASING NORTHWEST
WINDS...ALTHOUGH WILL STATE UP FRONT THAT THE INTENSITY/DURATION
OF THE STRONGEST WINDS HAS NOW TRENDED DOWNWARD A BIT OVER THE
PAST FEW MODEL RUNS...SO THIS WILL LIKELY BE A SOMEWHAT MARGINAL
WIND ADVISORY EVENT. WINDS WILL NOT START THE DAY ALL THAT
STRONG...AS IT WILL BE AT LEAST LATE MORNING/EARLY AFTERNOON
BEFORE INCREASING PRESSURE RISES AND DEEPENING MIXING BEHIND THE
INITIAL PASSING COLD FRONT RAMPS SPEEDS UP. ALOFT...THIS
INCREASING SURGE OF NORTHWEST WINDS WILL BE DRIVEN BY LOW
AMPLITUDE SHORTWAVE TROUGH DROPPING SOUTH OF SD INTO NEB/IA. HAVE
MADE NO CHANGES WHATSOEVER TO THE WIND ADVISORY ITSELF...STARTING
AT 11 AM AND ENDING AT 6 PM...WITH THE OVERALL BEST TIME FRAME FOR
SUSTAINED SPEEDS NEARING/MEETING 30 MPH WITH GUSTS 40 TO POSSIBLY
45 MPH CENTERED DURING THE MID-AFTERNOON. FARTHER SOUTH IN OUR KS
ZONES...AM GENERALLY EXPECTING SUSTAINED SPEEDS TO TOP OUT CLOSE
TO 25 MPH...THUS FALLING ABOUT 5 MPH SHORT OF ADVISORY CRITERIA SO
NOT ANTICIPATING ANY SOUTHWARD EXPANSION AT THIS TIME. HOURLY TEMP
TRENDS WILL BE TRICKY TODAY WITH A FAIRLY RAPID INITIAL RISE THEN
FOLLOWED BY A SLOW-BUT-STEADY FALL AS THE AFTERNOON WEARS ON AND
COLD AIR ADVECTION TAKES HOLD. HAVE FOLLOWED THE 06Z RAP SOLUTION
FAIRLY CLOSELY...WHICH ACTUALLY RESULTED IN ABOUT A 4 DEGREE
UPWARD BUMP TO HIGHS WITH MOST OF SOUTH CENTRAL NEBRASKA NOW
EXPECTED TO AT LEAST BRIEFLY TOUCH THE MID IF NOT UPPER 40S EXCEPT
COOLER FAR NORTH...AND KS ZONES RIGHT AROUND 50. THE ONLY CAVEAT HERE
IS WHETHER INCOMING MID/HIGH CLOUDS ARE THICK ENOUGH TO TEMPER
THINGS A BIT. PRECIPITATION WISE...KEPT ALL MENTION OUT OF THE
MORNING HOURS...BEFORE BRINGING IN NON-MEASURABLE CHANCES FOR
FLURRIES AND/OR SPRINKLES DURING THE AFTERNOON IN RESPONSE TO THE
INCOMING MID LEVEL SHORTWAVE TROUGH AND INCREASING UPPER JET
DYNAMICS. RAW MODEL QPF FIELDS CONTINUE TO BE ALL OVER THE
PLACE...AND ALTHOUGH THE MAJORITY OF THE CWA MAY NOT SEE A SINGLE
RAIN DROP OR SNOWFLAKE BEFORE SUNSET...IT SEEMS THE MOST FAVORED AREAS
WOULD BE NORTH OF NEBRASKA HWY 92 AND ALSO WITHIN THE SOUTHWEST
1/4 OF THE CWA.
THIS EVENING/TONIGHT...ALTHOUGH IT WILL REMAIN QUITE BREEZY EARLY
ON THIS EVENING...HAVE FAIRLY HIGH CONFIDENCE THAT THE WIND SPEEDS
WILL SAFELY FALL BELOW ADVISORY CRITERIA BY THE CURRENT EXPIRATION
TIME OF 6 PM...WITH SUSTAINED SPEEDS THEN STEADILY TRENDING DOWN
THROUGH THE REMAINDER OF THE NIGHT AS SURFACE HIGH PRESSURE SETTLES
IN FROM THE NORTHWEST. IN FACT AFTER MIDNIGHT...ONLY LOOKING AT SPEEDS
AROUND 10 MPH MOST AREAS. ALTHOUGH THE VAST MAJORITY OF THE CWA
WILL LIKELY REMAIN PRECIP-FREE TONIGHT...ITS OFTEN SEEN IN THIS
TYPE OF NORTHWEST FLOW PATTERN THAT EVEN SMALL BANDS/PATCHES OF
MID LEVEL CLOUDS COULD PRODUCE SOME SPORADIC FLURRIES...SO WILL
CONTINUE TO KEEP IT SIMPLE AND BLANKET THE ENTIRE CWA WITH THIS
SLIGHT FLURRY CHANCE. NUDGED DOWN LOW TEMPS GENERALLY 1-2 DEGREES
FROM PREVIOUS GRIDS...WITH MOST AREAS BOTTOMING OUT 15-19 DEGREES
ASSUMING THAT A CLOUD BAND DOESN/T PARK ITSELF SOMEWHERE AND HOLD
THINGS UP A BIT HIGHER.
FRIDAY INTO FRIDAY EVENING WILL HOLD THE BEST POTENTIAL FOR
A MORE WIDESPREAD COVERAGE OF FLURRIES AND POSSIBLY VERY LIGHT
SNOW ACCUMULATIONS IN A FEW AREAS...AS THE FINAL AND LIKELY MOST
VIGOROUS NORTHWEST-FLOW SHORTWAVE TROUGH DROPS SOUTHWARD ACROSS
THE HEART OF THE LOCAL AREA...FOCUSED WITHIN THE EXIT REGION OF A
RATHER STOUT MERIDIONAL UPPER JET OF 120+ KNOTS. ALTHOUGH WILL
KEEP AN OUTSIDE CHANCE OF A FLURRY GOING ON FRIDAY MORNING...HAVE
ADDED A SLIGHT CHANCE MEASURABLE POP TO THE AFTERNOON/EVENING
HOURS AS THE MAIN SHORTWAVE AXIS PASSES OVER. THIS IS LOOKING LIKE
A FAIRLY CLASSIC SETUP FOR QUICK NORTH-TO-SOUTH MOVING BRIEF SNOW
SHOWERS...GIVEN STEEP LOW LEVEL LAPSE RATES AND DEEP MIXING. THIS
SCENARIO IS WELL CAPTURED IN THE REFLECTIVITY PROG OF THE 00Z 4KM
WRF-NMM...WITH HIT AND MISS SNOW SHOWERS BLOSSOMING ACROSS THE
AREA DURING THE DAY BEFORE WEAKENING AND EVENTUALLY MOVING OUT
ALTOGETHER BY MIDNIGHT AS THE BACK EDGE OF THE MID LEVEL TROUGH
AXIS PASSES. THIS WILL BE A SITUATION WHERE SOME AREAS SEE A LIGHT
DUSTING OF SNOW...WHILE OTHERS MISS OUT COMPLETELY...AND AS THESE
MESOSCALE DETAILS BECOME CLEARER ITS POSSIBLE THAT POPS MIGHT BE
RAISED ABOVE THE CURRENT 20 PERCENT IN SOME AREAS. ALTHOUGH
AFTERNOON/EVENING WIND SPEEDS WILL NOT BE AS STRONG AS TODAY...AT
LEAST A FEW HOURS OF SUSTAINED 15-20 MPH SPEEDS IS
EXPECTED...WHICH COULD POSSIBLY RESULT IN LOCALIZED/BRIEF
VISIBILITY RESTRICTIONS UNDER PASSING SNOW SHOWERS...BUT NOT A
WIDESPREAD HAZARD WORTHY OF MENTION IN THE HWO AT THIS TIME.
TEMP-WISE...MADE A VERY SMALL UPWARD NUDGE TO PREVIOUS HIGHS BUT
THIS WILL STILL BE THE COLDEST DAY OF THE WEEK WITH HIGHS IN THE
30S MOST AREAS AND MAYBE ONLY UPPER 20S FAR NORTH. LIGHT WESTERLY
BREEZES LATE FRIDAY NIGHT SHOULD KEEP LOWS FROM TANKING TOO
FAR...BUT STILL DROPPING DOWN BETWEEN 14-18 MOST AREAS.
SATURDAY INTO SATURDAY NIGHT...HAVE RATHER HIGH CONFIDENCE IN A
DRY PERIOD WITH WARMING TEMPERATURES...AS THE BIG PICTURE ALOFT
INVOLVES AN INVADING SHORTWAVE RIDGE IN THE WAKE OF A DEEP
LONGWAVE TROUGH EXITING EASTWARD ACROSS THE EASTERN CONUS. IN THE
LOW LEVELS...WEST-SOUTHWEST BREEZES GENERALLY 10-15 MPH WILL
BRING IN SOME PRETTY STOUT WARM AIR ADVECTION DURING THE
DAY...ALTHOUGH THIS MAY BE TEMPERED SOMEWHAT BY WHAT COULD BE A
FAIRLY SOLID PASSING DECK OF MID CLOUDS. NO MATTER WHAT THOUGH...A
NOTABLE WARM-UP OVER FRIDAY IS IN STORE...AND BASED ON A BLEND OF
THE 00Z NAM/ECMWF RAISED 3-4 DEGREES FROM PREVIOUS FORECAST
ESPECIALLY ACROSS WESTERN COUNTIES...NOW CALLING FOR A RANGE FROM
LOW 40S EAST TO NEAR 50 WEST. SUPPOSE A FEW SPRINKLES FALLING OUT
OF THE AFOREMENTIONED MID DECK IS NOT OUT OF THE QUESTION...BUT
SEEMS UNLIKELY ENOUGH FOR NOW TO OMIT ANY GRID MENTION. SATURDAY
NIGHT...LIGHT WESTERLY BREEZES SHOULD KEEP LOW TEMPS SEVERAL
DEGREES WARMER THAN THE PREVIOUS FEW NIGHTS...AND MADE LITTLE
CHANGE WITH MID 20S MOST AREAS.
LONG TERM...SUNDAY THROUGH WEDNESDAY.
THE LONG TERM WILL CONSIST OF A SERIES OF PROGRESSIVE SHORTWAVE
TROUGHS AND RIDGES OF PACIFIC ORIGIN.
TOOK MORE OF A CONSENSUS APPROACH FOR THE LONG TERM...FAVORING
ENSEMBLE MEANS.
SUNDAY APPEARS THAT IT WILL BE THE MOST MILD DAY AS 850 MB
TEMPERATURES WARM UP NICELY IN ASSOCIATION WITH A PASSING SHORTWAVE
RIDGE. THERE WILL BE INCREASED WARMING JUST AHEAD OF AN APPROACHING
COLD FRONT...WITH SURFACE SOUTHWEST WIND DECREASING AS THE FRONT
APPROACHES...CONDITIONS COULD BECOME DOWNRIGHT SPRING-LIKE FOR THE
AFTERNOON.
COLDER AIR SPILLS IN FOR MONDAY...AND INCREASED WIND SPEEDS FROM THE
NORTH QUITE A BIT FROM ALLBLEND/CONSALL AS A RESULT OF THE HEALTHY
COLD AIR ADVECTION. THE COOL SURFACE HIGH FINALLY MAKES ITS WAY INTO
OUR AREA BY TUESDAY...WHICH SHOULD BE JUST ABOUT THE COOLEST HIGH
FOR THE LONG TERM BEFORE A BIT OF A REBOUND OCCURS FOR WEDNESDAY.
THIS REBOUND OCCURS AHEAD OF A DIGGING MEAN LONG TROUGH OVER THE
ROCKY MOUNTAINS WHICH WILL BE MOVING EAST.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 11 AM THIS MORNING TO 6 PM CST THIS EVENING
FOR NEZ039>041-046>049-060>064-072>077-082>087.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM/AVIATION...HEINLEIN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
529 AM CST THU FEB 14 2013
.UPDATE...
.AVIATION...
SCATTERED MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE
PASSAGE OF AN ARCTIC FRONT CURRENTLY AT 11Z NEAR KSDY. SCATTERED
SNOW SHOWERS AND MVFR WILL ACCOMPANY THE FRONT. MVFR AND ISOLATED SNOW
SHOWERS MAY PERSIST TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR
IS EXPECTED WITH ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY
TODAY. WINDS WILL INCREASE THIS AFTERNOON TO 32025G40KT AND
DECREASE AT SUNSET.
&&
.PREV DISCUSSION... /ISSUED 328 AM CST THU FEB 14 2013/
DISCUSSION...
NEAR TERM...TODAY AND TONIGHT.
SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE
PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD
REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT
THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT
STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH.
TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE.
THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF
GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT.
NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY.
WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE
UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE
HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD
SIGNALING A REINFORCING COLD FRONT FOR FRIDAY.
SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY.
BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL
REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING
SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER
JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP
WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND
FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY
DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY
NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH
HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN
PANHANDLE.
LONG TERM...12Z SUNDAY AND BEYOND.
SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE
ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO
THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER
THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON
SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL
HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER
THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S
SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH
THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR
PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES
COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO
MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR
BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT.
ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD
BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY.
SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT
BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE
MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE
CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE
DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED
TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER
PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE
POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED
YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW.
AVIATION...
MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN
ARCTIC FRONT CURRENTLY AT 08Z NEAR KGGW. SCATTERED SNOW SHOWERS WILL
ACCOMPANY THE FRONT. MVFR AND ISOLATES SNOW SHOWERS MAY PERSIST
TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH
ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 10 AM CST
/9 AM MST/ THIS MORNING TO 6 PM CST /5 PM MST/ THIS EVENING FOR
NEZ004>010-022>029-035>038-056>059- 069>071-094.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION....CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
328 AM CST THU FEB 14 2013
.DISCUSSION...
NEAR TERM...TODAY AND TONIGHT.
SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE
PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD
REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT
THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT
STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH.
TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE.
THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF
GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT.
NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY.
WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE
UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE
HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD
SIGNALING A REINFORCING COLD FRONT FOR FRIDAY.
SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY.
BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL
REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING
SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER
JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP
WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND
FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY
DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY
NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH
HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN
PANHANDLE.
LONG TERM...12Z SUNDAY AND BEYOND.
SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE
ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO
THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER
THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON
SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL
HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER
THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S
SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH
THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR
PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES
COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO
MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR
BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT.
ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD
BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY.
SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT
BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE
MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE
CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE
DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED
TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER
PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE
POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED
YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW.
&&
.AVIATION...
MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN
ARCTIC FRONT CURRENTLY AT 08Z NEAR KGGW. SCATTERED SNOW SHOWERS WILL
ACCOMPANY THE FRONT. MVFR AND ISOLATES SNOW SHOWERS MAY PERSIST
TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH
ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 10 AM CST
/9 AM MST/ THIS MORNING TO 6 PM CST /5 PM MST/ THIS EVENING FOR
NEZ004>010-022>029-035>038-056>059- 069>071-094.
&&
$$
SHORT TERM/LONG TERM...JACOBS
NEAR TERM/AVIATION....CDC
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1043 AM MST THU FEB 14 2013
.UPDATE...CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE
WESTERN GREAT LAKES...WITH A TIGHT PRESSURE GRADIENT IN PLACE TO
THE WEST ACROSS THE NORTHERN PLAINS. UPPER LEVEL ANALYSIS SHOWS
LOW OVER HUDSON BAY...WITH TROF ACROSS THE CENTRAL AND EASTERN
CONUS. STRONG JET FROM WESTERN CANADA THROUGH THE CENTRAL PLAINS
IS BRINGING NUMEROUS WEAK DISTURBANCES ACROSS THE REGION. CURRENT
ONE IS MOVING ACROSS THE NORTHERN HIGH PLAINS NOW. SKIES ARE
MAINLY CLOUDY ACROSS THE AREA...WITH SOME BREAKS ACROSS WESTERN
SD. KUDX RADAR SHOWING BANDS OF SNOW SHOWERS DEVELOPING PARALLEL
TO THE FLOW ACROSS FAR NORTHEASTERN WY AND WESTERN SD. THE
HEAVIEST SHOWERS CONTINUE TO BE ACROSS THE NORTHERN INTO WEST CENTRAL
BLACK HILLS...WHERE UP TO 6 INCHES HAS FALLEN IN THE FAVORED
HIGHER ELEVATIONS SINCE LATE YESTERDAY...ESPECIALLY NORTHWESTERN
PORTIONS OF THE BLACK HILLS. WINDS INCREASED AGAIN ACROSS THE
PLAINS EARLY THIS MORNING...WITH SOME GUSTS IN THE 50 TO 60 MPH
RANGE FROM 2WX TO RAP EARLIER THIS MORNING. TEMPS ARE MOSTLY IN
THE MID 20S TO LOWER 30S.
HAVE ONLY MADE MINOR CHANGES TO THE FORECAST FOR THE REST OF TODAY
AS SNOW SHOWERS CONTINUE TO DEVELOP AND TRACK SOUTHEAST ACROSS
THE AREA THROUGH THE AFTERNOON. LOW LEVEL INSTABILITY AND MOISTURE
IS SUFFICIENT FOR SCATTERED TO NUMEROUS COVERAGE OF SHOWERS FOR
MOST OF THE AREA. ADDITIONAL SNOWFALL AMOUNTS OF 1 TO 3 INCHES
ARE EXPECTED ACROSS THE NORTHERN BLACK HILLS AND BEAR LODGE
MTS...WITH THE HIGHEST AMOUNTS OVER NORTHWEST FACING SLOPES. ANY
ACCUMULATIONS ACROSS THE PLAINS WILL GENERALLY BE LESS THAN AN
INCH. SNOW SHOWERS WILL DECREASE IN COVERAGE ACROSS THE AREA LATE
THIS AFTERNOON AND EVENING AS INSTABILITY DIMINISHES. THE
COMBINATION OF SNOW SHOWERS AND WIND WILL BRIEFLY PRODUCE LOW
VISIBILITIES ACROSS THE PLAINS. THE STRONG WINDS ACROSS THE PLAINS
WILL CONTINUE INTO THE AFTERNOON...BUT START TO DIMINISH AFTER
21Z AS BEST PRESSURE RISES SHIFT EAST AND PRESSURE GRADIENT
WEAKENS. TEMPERATURES WILL REMAIN NEARLY STEADY IN MOST
AREAS...MID 20S TO MID 30S.
&&
.AVIATION...18Z TAFS
EXPECT SCT CONVECTIVE SHSN OVER THE AREA TODAY WITH LOCALIZED IFR
CIGS/VSBYS. SHSN ACTIVITY WILL WANE SOME TONIGHT...EXCEPT OVER THE
NORTHERN BLACK HILLS.
&&
PREV DISCUSSION... /ISSUED 349 AM MST THU FEB 14 2013/
DISCUSSION...UPPER LEVEL ANALYSIS HAS BROAD TROF OVER SOUTH
CENTRAL CANADA WITH RIDGE JUST OFF THE WEST COAST. IN
BETWEEN...FAST NORTHWEST FLOW IS PRESENT ACROSS THE NORTHERN
ROCKIES AND PLAINS WITH A 120KT JET DRIVING SEVERAL WEAK
SHORTWAVES THROUGH MONTANA INTO EASTERN WYOMING AND WESTERN SOUTH
DAKOTA. SKIES ARE MOSTLY CLOUDY WITH SOME SNOW CROSSING NORTHEAST
WYOMING AND THE BLACK HILLS AT THE MOMENT. AT THE SURFACE...LOW
PRESSURE IS LOCATED ACROSS CENTRAL NORTH DAKOTA AND EASTERN SOUTH
DAKOTA...WITH HIGH PRESSURE ACROSS THE NORTHERN AND CENTRAL
ROCKIES. TIGHT PRESSURE GRADIENT REMAINS ACROSS WESTERN SOUTH
DAKOTA...STILL PRODUCING WINDY CONDITIONS. TEMPERATURES RANGE FROM
THE 20S TO LOWER 30S.
FOR TODAY...CYCLONIC FLOW ALOFT REMAINS OVER THE AREA...WITH
SHORTWAVE ENERGY CONTINUING TO BRING SNOW TO MUCH OF THE AREA.
GREATEST CHANCES WILL BE OVER NORTHWEST SOUTH DAKOTA...AND ALSO
THE NORTHERN BLACK HILLS WHERE UPSLOPE ENHANCEMENT IS EXPECTED TO
CONTINUE. VERY GUSTY WINDS WILL CONTINUE THROUGH THE DAY AS
PRESSURE GRADIENT REMAINS TIGHT BEHIND SURFACE LOW. SURFACE LOW
SHIFTS EAST THIS AFTERNOON...ALLOWING GRADIENT TO RELAX...AND
WINDS TO SUBSIDE LATE IN THE AFTERNOON. TEMPERATURES WILL BE MUCH
COOLER TODAY AS CANADIAN HIGH PRESSURE SETTLES IN.
FOR FRIDAY...SNOW CHANCES LINGER THROUGH THE DAY...MAINLY OVER THE
WESTERN CWA...AS REGION REMAINS UNDER WEAK CYCLONIC FLOW ALOFT.
MODELS CONTINUE TO INDICATE UPSLOPE ENHANCEMENT THROUGH THE
DAY...THOUGH IT SHOULD COME TO AN END BY EVENING AS MOISTURE
DIMINISHES. TEMPERATURES WILL REMAIN BELOW AVERAGE ON FRIDAY.
ON SATURDAY...WESTERN UPPER RIDGE FINALLY PUSHES ACROSS THE
NORTHERN ROCKIES INTO THE NORTHERN PLAINS. DRY AND VERY MILD
CONDITIONS ARE EXPECTED...WITH HIGH TEMPERATURES IN THE 40S TO
LOWER 50S.
EXTENDED...THE MODELS ARE IN GOOD AGREEMENT WITH THE FORECAST FOR A
MODERATELY STRONG TROUGH CROSSING THE NORTHERN PLAINS SUNDAY NIGHT
THROUGH MONDAY NIGHT. THE SURFACE LOW IS EXPECTED TO DROP THROUGH
EASTERN NORTH DAKOTA PRODUCING A WRAP AROUND BAND OF POST FRONTAL
PRECIP OVER THE WESTERN DAKOTAS. THE NEXT SYSTEM WHICH IS FORECAST
TO CROSS THE CENTRAL PLAINS WEDNESDAY AND THURSDAY IS POSITIONED TO
DEVELOP A BROAD AREA OF UPWARD MOTION OVER THE FORECAST AREA...
ESPECIALLY THE EASTERN SLOPES OF THE BLKHLS AND SOUTH CENTRAL SOUTH
DAKOTA. THIS MIDWEEK SYSTEM IS ALSO ON A BETTER TRAJECTORY FOR
TAPPING INTO GULF MOISTURE. TEMPERATURES WILL DROP TO BELOW NORMALS
AFTER SUNDAY AND THEN CONTINUE TO COOL A FEW MORE DEGREES DURING MID
WEEK.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR
CENTRAL BLACK HILLS-NORTHERN BLACK HILLS.
WIND ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON FOR
BENNETT-BUTTE-CUSTER CO PLAINS-FALL RIVER-HAAKON-HARDING-
HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHERN FOOT HILLS-
NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID
CITY-SHANNON-SOUTHERN FOOT HILLS-SOUTHERN MEADE CO PLAINS-
STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-ZIEBACH.
WY...WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR
WYOMING BLACK HILLS.
&&
$$
SHORT TERM...26
LONG TERM....WFO UNR
AVIATION...HELGESON
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
944 PM EST FRI FEB 15 2013
.DISCUSSION...RAIN AND SNOW SHOWERS MAINLY OVER THE NORTHEASTERN
THIRD OF THE REGION...ACROSS SOUTHWEST VIRGINIA AND NORTHEAST
TENNESSEE AT THIS TIME. RUC AND NAM SHOW MOST PRECIPITATION ENDING
BY 06Z AS MAIN SHORTWAVE ASSOCIATED WITH TODAYS COLD FRONT MOVES
FARTHER EAST IN NC. UPDATED ZONES TO LOWER POPS A LITTLE MORE SOUTH
AND WEST FOR THE REST OF THE NIGHT. TEMPERATURES FALLING SLOWLY SO
CURRENT LOWS LOOK GOOD. MAY GET SOME CLEARING WEST BEFORE MORNING SO
LOWS THERE MAY BE A LITTLE TOO WARM. WINDS HAVE DECREASED ACROSS
THE FORECAST AREA SO WIND CHILLS NOT THAT SIGNIFICANT. UPDATED
FORECAST SENT.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 32 43 23 47 29 / 10 10 0 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 30 38 20 43 28 / 20 20 10 0 0
OAK RIDGE, TN 30 41 20 44 26 / 20 20 10 0 0
TRI CITIES AIRPORT, TN 28 37 17 35 21 / 30 30 20 10 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TD
AREA FORECAST DISCUSSION...UPDATED
NWS BLACKSBURG VA
955 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT MOVES EAST OF THE REGION OVERNIGHT...FOLLOWED BY A
STRONGER ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF
LOW PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE
CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE
ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE
APPALACHIANS LATE MONDAY NIGHT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 950 PM EST FRIDAY...
BASED ON ADDED SNOWFALL REPORTS OF AROUND 3 INCHES IN TAZEWELL CTY
ALONG WITH DEVELOPING SLICK ROAD CONDITIONS...WENT AHEAD WITH A
WINTER WEATHER ADVISORY THROUGH 4 AM FOR TAZEWELL...MERCER AND
BLAND CTYS WHERE COULD SEE UP TO 4 INCHES OF SNOW BEFORE THINGS
TAPER OFF TO FLURRIES.
AS OF 845 PM EST FRIDAY...
PERSISTENT BAND OF SNOW REMAINS ACROSS FAR SW VA INTO SE WVA ALONG
THE LEADING EDGE OF THE DEEPENING 5H TROF TO THE WEST AND UNDER A
WEAK SHORTWAVE AHEAD OF THE MAIN UPPER COLD POOL. WARM SURFACES
FROM EARLIER TODAY HAVE APPARENTLY LIMITED ACCUMULATIONS DESPITE
SEVERAL HOURS OF DECENT SNOWFALL WITH TOTALS OF 1-2 INCHES REPORTED
MAINLY ON GRASSY SURFACES. SINCE APPEARS WILL BE TAPERING SHORTLY
WONT HOIST AN ADVISORY YET UNLESS HEAVIER BANDS PERSIST LONGER.
OTRW LATEST RAP AND LOCAL RNK WRF SHOW THIS BAND OF SNOW FINALLY
WEAKENING BEFORE MIDNIGHT AS ENERGY SHIFTS EAST AND THE 85H FLOW
TURNS MORE NNW. THUS KEEPING IN A FEW MORE HOURS OF CAT/LIKELY
POPS THERE BEFORE DIMINISHING AFTER MIDNIGHT. OTRW COLD FRONT NOW
ENTERING THE PIEDMONT WITH A FEW RAIN SHOWER BANDS ALONG IT OVER
THE SE IN STRONG SW FLOW ALOFT DEPICTED OFF EVENING SOUNDINGS.
EXPECT THIS RAINFALL TO AFFECT AREAS MAINLY EAST OF THE BLUE RIDGE
BEFORE THE FRONT FINALLY GETS FAR ENOUGH EAST OF THE REGION TO
SUPPORT A LITTLE BETTER DOWNSLOPING IN THE NEXT FEW HOURS. THUS
THINKING WILL SEE A LULL IN PRECIP FOR THE MOST PART DURING THE
EARLY MORNING HOURS WITH THE FRONT TO THE SE...ONLY WEAK UPSLOPE
OVER THE WEST...AND LITTLE SUPPORT ALOFT AS WE SLIDE IN BETWEEN
UPPER IMPULSES LATER TONIGHT. THIS IN LINE WITH POPS FROM EARLIER
FOR AFTER MIDNIGHT SO ONLY TWEAKED POP COVERAGE LATER ON. HAVE
SEEN LITTLE SNOW IN THE ADVISORY AREA BUT LEAVING HEADLINES AS IS
FOR NOW. TEMPS SLOW TO FALL OUT EAST BUT WILL GET INTO BETTER COLD
ADVECTION SHORTLY WITH THE LAV MOS LOOKING TOO WARM MOST SPOTS
OVERNIGHT.
PREVIOUS DISCUSSION...
A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS
AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS
UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS
FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP
WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST
AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR
A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP
MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD
LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR
AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE
GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND
A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE
HEAVIEST AMOUNTS OUT OF FORECAST AREA.
STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS
FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS
TO THE EAST AND NO HEADLINES.
AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND
UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST
VIRGINIA.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 408 PM EST FRIDAY...
LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE
MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD
JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT.
DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD
ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST.
ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN
SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME
SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL
DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE
DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE
WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND
6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN
INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET.
WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC
WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS
CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND
GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY
NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A
SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE
DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING
AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER
TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE
GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE
MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF
SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 350 PM EST FRIDAY...
HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT
TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY
STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY
HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL
PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH
HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING
CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING
CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES
ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE
COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE
SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND
PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE
JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE
SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL
CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO
FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER
RIDGES ALONG THE BLUE RIDGE.
HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH
BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED
TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT
PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z
GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION
FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A
PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING
DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT
FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST
SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE
THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO
BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER
AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE
OHIO VALLEY PER THE ECMWF.
TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH
PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY
AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH
A WET COLD AIR DAMMING EVENT EXPECTED.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
AS OF 555 PM EST FRIDAY...
COLD FRONT NOW CROSSING INTO WESTERN VIRGINIA WITH BROKEN AREAS OF
LIGHT TO MODERATE RAIN/SNOW ALONG AND BEHIND THE BOUNDARY ATTM.
LOCAL WRF SEEMS TO STILL HAVE THE BEST HANDLE SO WILL FOLLOW
CLOSELY AND PUSH RAIN A BIT FARTHER EAST THIS EVENING TO PERHAPS
KLYH SINCE GOOD DOWNSLOPE IS LAGGING THE FRONT. OTRW WILL HAVE
PERIODIC MVFR TO IFR AT KBLF...AND MOSTLY MVFR AT KLWB AS
EXPECTING BEST COVERAGE OF SNOW TO SLIDE SOUTH OF THAT AREA THIS
EVENING. MAY ALSO INCLUDE A PERIOD OF MVFR AT BOTH KBCB/KROA WITH
MOSTLY -SHRA AT ROANOKE AND PERHAPS A MIX TO SNOW AT KBCB BEFORE
THINGS START TO TAPER OFF SOME LATER THIS EVENING. ELSW WILL
MAINTAIN VFR OUT EAST PENDING JUST HOW FAR THE PRECIP GETS IN THE
NEXT FEW HOURS. KLWB AND KBLF WILL TRANSITION TO AN UPSLOPING PCPN
-SHSN EVENT AROUND MIDNIGHT IF NOT SOONER AND CONTINUE THROUGH
TOMORROW. STILL LOOKING FOR MVFR CIGS/VSBYS AND EXPECT -SHSN TO BE
LIGHT.
KDAN IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT
DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST
WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD. IT CURRENTLY LOOKS LIKE
KDAN WILL BE ON THE EDGE OF THIS AND WILL KEEP SOME BORDERLINE VFR CIGS
IN AFTER 12Z ALONG WITH SOME PCPN THAT MAY BE ALL SNOW DURING THE
MORNING.
LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN
RESPONSE TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT
WINDS TO HAMPER AVIATION INTERESTS THROUGH THIS TAF PERIOD.
EXTENDED AVIATION DISCUSSION...
REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS
DISCUSSION:
HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY
SUNDAY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A
NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH
MVFR/IFR CEILINGS. VFR QUICKLY RETURNS ON WEDNESDAY WITH HIGH
PRESSURE FOLLOWING THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR VAZ007-010.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018.
WV...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR WVZ042.
&&
$$
SYNOPSIS...AMS/KM
NEAR TERM...AMS/JH/PH
SHORT TERM...KM
LONG TERM...RCS
AVIATION...AMS/JH/NF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
918 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT MOVES EAST OF THE REGION OVERNIGHT...FOLLOWED BY A
STRONGER ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF
LOW PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE
CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE
ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE
APPALACHIANS LATE MONDAY NIGHT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 845 PM EST FRIDAY...
PERSISTENT BAND OF SNOW REMAINS ACROSS FAR SW VA INTO SE WVA ALONG
THE LEADING EDGE OF THE DEEPENING 5H TROF TO THE WEST AND UNDER A
WEAK SHORTWAVE AHEAD OF THE MAIN UPPER COLD POOL. WARM SURFACES
FROM EARLIER TODAY HAVE APPARENTLY LIMITED ACCUMULATIONS DESPITE
SEVERAL HOURS OF DECENT SNOWFALL WITH TOTALS OF 1-2 INCHES REPORTED
MAINLY ON GRASSY SURFACES. SINCE APPEARS WILL BE TAPERING SHORTLY
WONT HOIST AN ADVISORY YET UNLESS HEAVIER BANDS PERSIST LONGER.
OTRW LATEST RAP AND LOCAL RNK WRF SHOW THIS BAND OF SNOW FINALLY
WEAKENING BEFORE MIDNIGHT AS ENERGY SHIFTS EAST AND THE 85H FLOW
TURNS MORE NNW. THUS KEEPING IN A FEW MORE HOURS OF CAT/LIKELY
POPS THERE BEFORE DIMINISHING AFTER MIDNIGHT. OTRW COLD FRONT NOW
ENTERING THE PIEDMONT WITH A FEW RAIN SHOWER BANDS ALONG IT OVER
THE SE IN STRONG SW FLOW ALOFT DEPICTED OFF EVENING SOUNDINGS.
EXPECT THIS RAINFALL TO AFFECT AREAS MAINLY EAST OF THE BLUE RIDGE
BEFORE THE FRONT FINALLY GETS FAR ENOUGH EAST OF THE REGION TO
SUPPORT A LITTLE BETTER DOWNSLOPING IN THE NEXT FEW HOURS. THUS
THINKING WILL SEE A LULL IN PRECIP FOR THE MOST PART DURING THE
EARLY MORNING HOURS WITH THE FRONT TO THE SE...ONLY WEAK UPSLOPE
OVER THE WEST...AND LITTLE SUPPORT ALOFT AS WE SLIDE IN BETWEEN
UPPER IMPULSES LATER TONIGHT. THIS IN LINE WITH POPS FROM EARLIER
FOR AFTER MIDNIGHT SO ONLY TWEAKED POP COVERAGE LATER ON. HAVE
SEEN LITTLE SNOW IN THE ADVISORY AREA BUT LEAVING HEADLINES AS IS
FOR NOW. TEMPS SLOW TO FALL OUT EAST BUT WILL GET INTO BETTER COLD
ADVECTION SHORTLY WITH THE LAV MOS LOOKING TOO WARM MOST SPOTS
OVERNIGHT.
PREVIOUS DISCUSSION...
A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS
AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS
UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS
FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP
WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST
AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR
A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP
MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD
LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR
AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE
GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND
A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE
HEAVIEST AMOUNTS OUT OF FORECAST AREA.
STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS
FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS
TO THE EAST AND NO HEADLINES.
AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND
UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST
VIRGINIA.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 408 PM EST FRIDAY...
LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE
MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD
JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT.
DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD
ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST.
ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN
SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME
SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL
DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE
DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE
WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND
6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN
INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET.
WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC
WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS
CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND
GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY
NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A
SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE
DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING
AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER
TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE
GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE
MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF
SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 350 PM EST FRIDAY...
HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT
TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY
STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY
HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL
PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH
HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING
CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING
CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES
ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE
COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE
SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND
PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE
JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE
SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL
CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO
FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER
RIDGES ALONG THE BLUE RIDGE.
HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH
BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED
TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT
PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z
GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION
FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A
PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING
DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT
FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST
SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE
THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO
BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER
AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE
OHIO VALLEY PER THE ECMWF.
TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH
PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY
AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH
A WET COLD AIR DAMMING EVENT EXPECTED.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
AS OF 555 PM EST FRIDAY...
COLD FRONT NOW CROSSING INTO WESTERN VIRGINIA WITH BROKEN AREAS OF
LIGHT TO MODERATE RAIN/SNOW ALONG AND BEHIND THE BOUNDARY ATTM.
LOCAL WRF SEEMS TO STILL HAVE THE BEST HANDLE SO WILL FOLLOW
CLOSELY AND PUSH RAIN A BIT FARTHER EAST THIS EVENING TO PERHAPS
KLYH SINCE GOOD DOWNSLOPE IS LAGGING THE FRONT. OTRW WILL HAVE
PERIODIC MVFR TO IFR AT KBLF...AND MOSTLY MVFR AT KLWB AS
EXPECTING BEST COVERAGE OF SNOW TO SLIDE SOUTH OF THAT AREA THIS
EVENING. MAY ALSO INCLUDE A PERIOD OF MVFR AT BOTH KBCB/KROA WITH
MOSTLY -SHRA AT ROANOKE AND PERHAPS A MIX TO SNOW AT KBCB BEFORE
THINGS START TO TAPER OFF SOME LATER THIS EVENING. ELSW WILL
MAINTAIN VFR OUT EAST PENDING JUST HOW FAR THE PRECIP GETS IN THE
NEXT FEW HOURS. KLWB AND KBLF WILL TRANSITION TO AN UPSLOPING PCPN
-SHSN EVENT AROUND MIDNIGHT IF NOT SOONER AND CONTINUE THROUGH
TOMORROW. STILL LOOKING FOR MVFR CIGS/VSBYS AND EXPECT -SHSN TO BE
LIGHT.
KDAN IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT
DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST
WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD. IT CURRENTLY LOOKS LIKE
KDAN WILL BE ON THE EDGE OF THIS AND WILL KEEP SOME BORDERLINE VFR CIGS
IN AFTER 12Z ALONG WITH SOME PCPN THAT MAY BE ALL SNOW DURING THE
MORNING.
LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN
RESPONSE TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT
WINDS TO HAMPER AVIATION INTERESTS THROUGH THIS TAF PERIOD.
EXTENDED AVIATION DISCUSSION...
REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS
DISCUSSION:
HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY
SUNDAY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A
NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH
MVFR/IFR CEILINGS. VFR QUICKLY RETURNS ON WEDNESDAY WITH HIGH
PRESSURE FOLLOWING THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018.
WV...NONE.
&&
$$
SYNOPSIS...AMS/KM
NEAR TERM...AMS/JH/PH
SHORT TERM...KM
LONG TERM...RCS
AVIATION...AMS/JH/NF
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
532 PM CST FRI FEB 15 2013
.SHORT TERM...THROUGH MONDAY NIGHT
319 PM CST FRI FEB 15 2013
BENIGN WEATHER THROUGH THE WEEKEND LEADS INTO MONDAYS WEATHER
SYSTEM WHICH WILL NEED TO BE WATCHED FOR CHANGES.
MUCH LESS CLOUD ACROSS THE AREA TODAY THAN FORECAST WITH MIXING
NOT DEEP ENOUGH TO FORM MUCH STRATOCUMULUS EXCEPT OVER
NORTH-CENTRAL WI. LONGWAVE TROUGH AXIS CONTINUES EASTWARD PROGRESS
WITH LAST OF SHORTWAVE TROUGH ENERGY COMING THROUGH TONIGHT AND
EARLY SATURDAY. LATEST RAP AND WATER VAPOR HAS THIS BROAD
CIRCULATION AXIS FROM KINL-KLBF...AND SURFACE LOW PRESSURE IN
EASTERN NEB. CLOUD COVER OVER NWRN MN MOVING TOWARD THE AREA WILL
ARRIVE THIS EVENING FOR A CLOUD PERIOD INTO SATURDAY MORNING. NOT
TO CONFIDENT ON THE COVERAGE OF THIS CLOUD COMING IN...IT MAY BE
MORE IN AREAS. HAVE LEFT A MENTION OF FLURRIES IN THIS WEAKLY
LIFTED AIR MASS THROUGH NOON SATURDAY.
AGGRESSIVE RIDGE BUILDING THEN TAKES PLACE LATER SATURDAY AND
SUNDAY. UPSTREAM RAOB HEIGHT RISES SEEN ACROSS WRN CANADA WITH
THIS PROGRESSIVE HIGHER AMPLITUDE RIDGE. HAVE COOLED THE LOW
TEMPERATURES SUNDAY MORNING OVER CENTRAL WI WITH NEARLY CALM WINDS
AND LITTLE CLOUD UNDER LOW-LEVEL RIDGING. THESE ARE BELOW MOS
GUIDANCE BY ABOUT 5-7F. WARM ADVECTION WILL BEGIN TO RAISE
TEMPERATURES SUNDAY AND THE FORCING DOES NOT SEEM SUFFICIENT TO
CREATE PRECIPITATION PER CONSENSUS 15.12Z MODEL GUIDANCE.
HOWEVER...THE WARM ADVECTION AND THERMAL RIBBON LIFTING ACROSS THE
AREA WILL CREATE AN ARC OF CLOUDS ORIENTED NW-SE TO SHIFT NEWRD
ACROSS THE AREA. HAVE INCREASED SKY COVER A BIT FOR SUNDAY...SOME
FLURRIES MAY BE POSSIBLE BUT HAVE NOT INCLUDED THEM IN THE
FORECAST.
FAIRLY INTERESTING TROUGH TO SHIFT INTO THE AREA MONDAY. THE
TROUGH IS CURRENTLY IN THE ERN PACIFIC APPROACHING 47N/140W PER
GOES WATER VAPOR. MODEL GUIDANCE CONSENSUS FROM 15.12Z IS THAT
THERE WILL NRN AND SRN ENERGY IN THIS TROUGH. THE SRN PIECE OF
ENERGY IS HANDLED DIFFERENTLY BY THE LATEST GUIDANCE. THE 15.12Z
NAM/SREF DEVELOP ONLY A WEAK CYCLONE VIA THE SRN ENERGY...WHILE THE
GEM GLOBAL AND 15.00Z FIM MODEL ARE AGGRESSIVE WITH THE CYCLONE
DEEPENING IT ALONG A KANSAS CITY TO MILWAUKEE TRACK...AND DROPPING
A 4-8 INCH SNOW BAND ACROSS WI. 15.12Z ECMWF/GFS ARE SIMILAR AND
OFFER A COMPROMISE BETWEEN THE TWO CAMPS WITH THE CYCLONE
DEEPENING LATER...INTO MICHIGAN. HAVE GONE WITH THIS COMPROMISE ON
TIMING AND INTENSITY.
MONDAY WILL SEE A GULF SURGE OF MOISTURE IN THE SOUTHERLY FLOW...
DEEPENING A SURFACE-BASED LAYER TO OVER 1 KM DEEP. THIS WILL BE
PRE-FRONTAL IN THE SOUTHERLY FLOW AND WITHOUT DEEP CLOUD AND
ICE...BUT ISENTROPIC LIFT OF 3-5 UB/S IN THE LAYER ...DZ/FZDZ
WILL BE POSSIBLE. THE MOIST TONGUE IS MAINLY IN WI AND EAST AND
THAT IS WHERE DZ/FZDZ CHANCES WILL BE BEST. TEMPERATURES WILL BE
WARMING MONDAY WITH ABOVE FREEZING HIGHS AROUND I-90 AND SOUTH
EXPECTED. THUS...DZ OR RAIN SHOWERS COULD BE FREEZING IN THE EARLY
AFTERNOON IF ROADS DO NOT RESPOND TO WARMING. WITH QPFS LESS THAN
0.10 INCHES...WOULD EXPECT ONLY LIGHT ICING TO OCCUR. AS TROUGH
SHIFTS EAST LATE MONDAY AND MONDAY EVENING...A TRANSITION TO SNOW
WILL OCCUR FROM WEST TO EAST WITH SNOW AMOUNTS OF LESS THAN AN
INCH. HAVE INCREASED PRECIPITATION CHANCES OVERALL...BUT WI LOOKS
TO BE THE MAIN WEATHER AREA FOR THIS SYSTEM. THERE IS A CHANCE
THIS COULD NEED AN ADVISORY IF FREEZING PRECIPITATION LOOKS MORE
WIDESPREAD OR THE MORE AGGRESSIVE CYCLONE SOLUTION IN THE GEM
SHOULD BECOME MORE PROBABLE. THE SPREAD IN THE CYCLOGENESIS SEEN
FROM THE SRN ENERGY IN THE MODEL GUIDANCE SUGGESTS THIS IS AN
UNSTABLE SYSTEM AND COULD LEAD TO FORECAST CHANGES. WILL TAKE A
STEP UP IN OUR FORECAST VISIBILITY OF THIS SYSTEM.
.LONG TERM...TUESDAY THROUGH FRIDAY
319 PM CST FRI FEB 15 2013
ACTIVE EXTENDED PERIOD SETTING UP WITH THE FOCUS ON A SHORT ARCTIC
INTRUSION MID WEEK FOLLOWED BY THE POTENTIAL OF A WINTER STORM TO
IMPACT THE UPPER MIDWEST NEXT THURSDAY NIGHT AND FRIDAY.
GOING INTO TUESDAY...A LOT DEPENDS ON THE EVOLUTION AND PHASING OF
THE STORM SYSTEM THAT IS EXPECTED TO TRACK THROUGH MONDAY AND MONDAY
NIGHT...AND HOW MUCH ARCTIC AIR IS PULLED SOUTH IN ITS WAKE. 15.12Z
GUIDANCE SHOWS SIMILAR SOLUTIONS FOR 850 MB TEMPERATURES TO PLUMMET
AS LOW AS -15C TO -20C TUESDAY AND WEDNESDAY. STANDARDIZED
ANOMALIES FOR THIS PERIOD RANGE FROM 1 TO 1.5 BELOW NORMAL AND WITH
BROAD CYCLONIC FLOW ALOFT...IT WILL MAKE FOR A COUPLE COLD WINTER
DAYS. HIGHS IN THE TEENS AND OVERNIGHT LOWS IN THE SINGLE DIGITS
ABOVE ZERO...WITH OCCASIONAL LIGHT SNOW OR FLURRIES TUESDAY.
THE COLD AIRMASS SETS THE STAGE FOR LATER IN THE WEEK AS A WESTERN
CONUS TROUGH DEEPENS AND MOVES EAST. AS HAS BEEN ALLUDED TO IN
PREVIOUS DISCUSSIONS...THE RUN-TO-RUN AND MODEL CONSISTENCY FOR
THIS FEATURE REMAINS VERY HIGH. DETERMINISTIC MODELS STILL POINT
FOR A SURFACE LOW TRACK THROUGH THE CENTRAL PLAINS TO NORTHERN
ILLINOIS BY 12Z FRIDAY BRINGING WIDESPREAD PRECIPITATION TO THE
ENTIRE AREA WITH A CLASSIC DEFORMATION BAND OF SNOW SETTING UP.
LOOKING AT THE 15.12Z GFS ENSEMBLE...SURFACE LOW TRACK LOCATIONS
VARY FROM EASTERN IOWA...SOUTHERN WISCONSIN...AND ILLINOIS.
SIMILAR IDEAS ARE FOUND IN THE 15.00Z ECMWF ENSEMBLE. THE
STABILITY AND LACK OF SPREAD WITHIN THE NUMERICAL GUIDANCE FOR
THIS WEATHER SYSTEM ARE VERY HIGH.
ONE ISSUE THAT MAY PRECLUDE THIS FROM BEING A MORE SIGNIFICANT EVENT
IS THAT THE BOTH THE UPPER LEVEL AND SURFACE WAVES APPEAR TO BE
WEAKENING AS IT APPROACHES THE UPPER MIDWEST. 500 MB STANDARDIZED
ANOMALIES DROP FROM -2.5 ACROSS KANSAS TO BARELY BELOW NORMAL AS IT
CROSSES THE AREA. THIS IS REFLECTED IN THE SURFACE LOW PRESSURE
WHICH REMAINS AROUND 1000 MB THROUGHOUT. EARLIER RUNS SHOWED DEEPER
CYCLOGENESIS WITH 980-990 MB LOWS. THE 15.12Z ECMWF REALLY DAMPENS
OUT THE UPPER LEVEL AND SURFACE WAVE...BECOMING ALMOST OCCLUDED BY
FRIDAY AFTERNOON.
TEMPERATURE PROFILES ACROSS THE AREA CONTINUE TO SHOW AN ALL SNOW
EVENT...THOUGH THERE IS A SLIGHT WARMING TREND NOTED. IF THE
SYSTEM WERE TO DEEPEN AND WRAP UP MORE...THEN A PUSH OF WARMER AIR
COULD PRESENT A RAIN/SNOW MIX BUT RIGHT NOW THIS IS NOT THE CASE.
HAVE TRENDED PRECIPITATION CHANCES ABOVE MODEL CONSENSUS THURSDAY
NIGHT GIVEN CONTINUED EXCELLENT MODEL AGREEMENT AND THE SLOWER
TIMING OF THE SYSTEM.
ALTHOUGH IT IS A BIT TOO EARLY TO SPECULATE ON AMOUNTS...25.12Z GFS
ENSEMBLE AND 25.12Z ECMWF SHOW WIDESPREAD AMOUNTS OF 0.50 TO 0.75
INCHES OF LIQUID. SNOW RATIOS ARE NOT VERY HIGH...MOST LIKELY A BIT
BELOW CLIMATOLOGICAL VALUES /10 TO 12:1/ SO IN SHORT...WARNING
LEVEL /6 INCHES/ SNOW TOTALS COULD BE MET OR EXCEEDED ACROSS PARTS
OF THE REGION.
&&
.AVIATION...TONIGHT AND SATURDAY
532 PM CST FRI FEB 15 2013
DESPITE THE CLEAR SKIES TO BEGIN THE AVIATION FORECAST...THE
FORECAST IS QUITE DIFFICULT. THE PROBLEM IS TRYING TO FIGURE OUT
IF AND WHEN STRATUS WOULD MOVE INTO THE TAF SITES FROM THE
NORTHWEST. PRESENTLY THERE ARE AREAS OF MVFR STRATUS OVER THE
EASTERN DAKOTAS AND MOSTLY VFR STRATUS ACROSS NORTHERN MINNESOTA.
WITH A NORTHWEST FLOW AND NOW HEADING INTO THE NIGHTTIME COOLING
PERIOD...IT SHOULD BE EASIER FOR THE STRATUS TO FLOW TOWARDS THE
TAF SITES. MODELS SUCH AS THE RAP THAT HAVE A BETTER HANDLE ON THE
CURRENT LOW LEVEL MOISTURE SITUATION PROG THESE CLOUDS TO MOVE
INTO THE TAF SITES AROUND 09Z...A LITTLE LATER THAN PREVIOUSLY
FORECAST. MVFR CEILINGS STILL SEEM THE WAY TO GO. THERE CERTAINLY
COULD BE SOME FLURRIES WITH THIS STRATUS...BUT LACK THEREOF
UPSTREAM ALONG WITH CONFIDENCE OF THE STRATUS IMPACTING THE TAF
SITES BEING LESS THAN AVERAGE HAS RESULTED IN REMOVAL OF FLURRIES.
IF THE STRATUS DOES INDEED MOVE INTO THE TAF SITES...NEXT QUESTION
WOULD BE WHEN DOES IT CLEAR. WITH A SURFACE RIDGE OVER THE EASTERN
DAKOTAS MOVING OVERHEAD ON SATURDAY...THE LIGHTER WINDS ASSOCIATED
WITH IT MAKE MIXING A LITTLE MORE DIFFICULT. HOWEVER...THE HIGHER
SUN ANGLE NOW SHOULD ALLOW THE CLOUDS TO SCATTER OUT BY 20Z.
NEEDLESS TO SAY...A LOW CONFIDENCE FORECAST WITH WHETHER
CONDITIONS CAN STAY VFR OR END UP WITH MVFR CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
319 PM CST FRI FEB 15 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...TAYLOR/BAUMGARDT
AVIATION...AJ
AREA FORECAST DISCUSSION...CORRECTED
NWS MILWAUKEE/SULLIVAN WI
353 PM CST THU FEB 14 2013
.SHORT TERM...
.TONIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM.
SURFACE LOW MOVES NORTHEAST FROM LAKE HURON TO SOUTHERN QUEBEC AS
HIGH PRESSURE BUILDS INTO THE NORTHERN AND CENTRAL PLAINS. DECENT
SHORTWAVE MOVING BY JUST TO OUR SOUTHWEST EARLY THIS EVENING.
HOWEVER...APPEARS PRECIP...OTHER THAN FLURRIES...WILL STICK TO OUR
SOUTHWEST. MODELS AGREE ON KEEPING MAIN AREA OF PRECIP TO THE
SOUTHWEST. ALSO...EXTRAPOLATION OF CURRENT SWATH OF LIGHT SNOW
ASSOCIATED WITH VORT MAX OVER CENTRAL IOWA WOULD SHOW MAIN AREA OF
PRECIP MOVING TO OUR SOUTHWEST.
LIGHT SNOW/FLURRIES WRAPPING AROUND THE LOW IN EAST CENTRAL
WISCONSIN WILL EXIT THIS EVENING AS THE LOW LIFTS NORTHEAST.
HOWEVER...KEPT FLURRY MENTION IN FOR THE NIGHT UNTIL DRY AIR
CURRENTLY IN MINNESOTA MOVES IN.
THE CLEARING AREA IN MINNESOTA HAS EXPANDED...AND MATCHES UP WELL
WITH THE RAP 850MB RH. WOULD HAVE THIS GETTING TO OUR WEST/NORTHWEST
AREA SOMETIME AROUND MIDNIGHT...PUTTING A HALT TO FLURRIES AS IT
MOVES IN. THIS COULD CREATE A PROBLEM FOR TONIGHT/S LOWS...COULD SEE
TEMPS REALLY DROP IF SIGNIFICANT CLEARING TAKES PLACE.
A WEAKER SHORTWAVE MOVES THROUGH TOMORROW AFTERNOON...SO EXPECTING
CLOUD COVER TO INCREASE FRIDAY MORNING WITH FLURRIES RETURNING.
THERE IS SOME PVA AND WAA BETWEEN 850 AND 700MB IN THE
AFTERNOON...BUT OVERALL NOT IMPRESSED BY Q VECTOR CONVERGENCE.
925MB COLD AIR ADVECTION TAKES HOLD TONIGHT. 925MB TEMPS DROP FROM
AROUND -3 TO -5C AT 00Z FRIDAY TO -11 TO -13C BY 12Z FRIDAY. NOT TOO
MUCH OF A REBOUND FOR FRIDAY EITHER. HIGHEST 925MB TEMPS ON FRIDAY
ABOUT -10 TO -12C. HOWEVER...MODELS HAVE BEEN A BIT COOL WHERE SNOW
PACK ISN/T AS SIGNIFICANT. PUT IN HIGHS IN THE 22-27F RANGE.
SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
SOUTHERN WISCONSIN IS ON THE WESTERN PERIPHERY OF THE LARGE UPPER
TROUGH AXIS. MODELS SHOW SHEARED CYCLONIC VORTICITY AXIS MOVING
ACROSS SOUTHERN WISCONSIN. SATURATED LOW LEVELS BELOW AN INVERSION
AROUND 5 THSD FT WITH STEEP LAPSE RATES BELOW THE INVERSION. SOME
FLURRY POTENTIAL.
SURFACE RIDGE AXIS THEN NUDGES INTO WESTERN WISCONSIN BY THE END
OF THE DAY.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE...MEDIUM
TO HIGH
THE HIGH PRESSURE RIDGE SHIFTS EAST OF AREA WITH THE PLAINS
TROUGH APPROACHING. WARM ADVECTION UNDERWAY THROUGH THIS PERIOD.
WARMEST 925 TEMPS ARRIVE SUNDAY NIGHT WITH READINGS RISING TO AT
OR ABOVE 0 CELSIUS. SHOULD BE A NON DIURNAL TEMPERATURE TREND
WITH RISING TEMPERATURES.
MONDAY AND MONDAY NIGHT FORECAST CONFIDENCE...MEDIUM TO HIGH
THE MID/UPPER LEVEL UPPER TROUGH EXITS THE NORTHERN AND CENTRAL
PLAINS MONDAY AND MOVES INTO THE WESTERN GREAT LAKES MONDAY NIGHT.
A DECENT SURGE OF MOISTURE ADVECTS NORTHWARD AHEAD AND ALONG OF
THE LOWER LEVEL TROUGH. GFS/GEM AND ECMWF ALL SHOW PRECIP ARRIVING
MONDAY AFTERNOON AND MONDAY NIGHT. THICKNESS AND 850 MB
TEMPERATURES TREND TOWARD A MIX OR MAINLY SNOW EXCEPT FAR
SOUTHEAST. HOWEVER GFS FORECAST SOUNDING SHOW A WARM BOUNDARY
LAYER WHICH WOULD BRING MORE RAIN SOUTH AND RAIN/SNOW NORTH.
850/925 TEMPS THEN COLLAPSE DURING THE EVENING TRANSITIONING THE
PRECIPITATION TO SNOW.
.LONG TERM...
TUESDAY...FORECAST CONFIDENCE...MEDIUM
LINGERING CYCLONIC FLOW FROM THE DEPARTING MID LEVEL TROUGH SUGGESTS
KEEPING SOME SMALL POPS EAST FOR SNOW SHOWERS EARLY. THEN
PRONOUNCED DRYING. DECENT COLD ADVECTION EXPECTED BEHIND THE
STRENGTHENING LOW TO THE EAST/NORTHEAST.
WEDNESDAY...FORECAST CONFIDENCE...
BROAD CYCLONIC FLOW MOVES OFF AS A MID LEVEL RIDGE MOVES ACROSS
WISCONSIN. A RATHER STRONG CANADIAN HIGH WILL BE RIDGING SOUTHEAST
INTO THE AREA CONTINUING THE COLD TEMPERATURES.
THURSDAY...FORECAST CONFIDENCE...
STRONG SHORTWAVE OVER THE SOUTHWEST U.S. LIFTS NORTHEAST. MAIN
DIFFERENCE IS THAT THE 12Z ECMWF IS SOMEWHAT SLOWER AND FARTHER SOUTH.
GFS AND ECMWF BOTH BRING A STRONG LOW THAT WOULD FAVOR HEAVY SNOW
EVENTUALLY AFFECTING PORTIONS OF THE FORECAST AREA. THE ECMWF IS A
FAVORABLE TRACK FOR HEAVY SNOW OVER SOUTHEAST WISCONSIN...WITH THE
GFS A LITTLE FARTHER NORTH. HEAVY PRECIPITATION AMOUNTS ON BOTH
MODELS...WITH THE HEAVIEST ON THE GFS. THIS WILL BE A POTENTIAL
SNOWSTORM FOR LATER THURSDAY OR FRIDAY. PREFER THE SOMEWHAT SLOWER
ECMWF SO WILL NOT RAISE POPS FROM THE CONSENSUS GRIDS ON THURSDAY.
&&
.AVIATION/00Z TAFS/...
VFR CEILINGS WERE WEST OF ABOUT A JANESVILLE TO GREEN LAKE LINE
AROUND MID AFTERNOON. THINKING THESE CONDITIONS WILL SPREAD EAST
THIS EVENING AS THE SURFACE LOW MOVES EAST. NAM AND GFS SOUNDINGS
QUITE DIFFERENT IN TERMS OF CEILING HEIGHT. THINKING THE SOLUTION IS
SOMEWHERE IN THE MIDDLE BASED ON UPSTREAM OBS. LEANING TOWARDS VFR
CONDITIONS FOR THE MAJORITY OF THE NIGHT ONCE THE LOW MOVES EAST.
AREA OF DRY AIR OVER MINNESOTA HAS EXPANDED AND WILL LIKELY ARRIVE
IN OUR AREA AFTER MIDNIGHT. MORE CONFIDENT IN VFR CONDITIONS THEN.
COULD SEE SCATTERED FLURRIES TONIGHT UNTIL DRY AIR OVER MINNESOTA
MOVES IN. NOT EXPECTING ANY ACCUMULATION AT THE TAF SITES THOUGH.
CLOUDS WILL BUILD BACK IN FRIDAY MORNING AS ANOTHER SHORTWAVE
APPROACHES. THIS WILL BRING ANOTHER CHANCE FOR FLURRIES AS WELL. NOT
EXPECTING MUCH IF ANY ACCUMULATION.
&&
.MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH MIDNIGHT TONIGHT AS LOW
PRESSURE MOVES OFF TO THE NORTHEAST. SOUNDINGS SHOW WIND GUSTS
DIMINISHING AFTER MIDNIGHT. HOWEVER...THE PRESSURE GRADIENT IS STILL
FAIRLY TIGHT THROUGH FRIDAY MORNING AND THERE COULD BE A FEW GUSTS
TO CRITERIA AFTER MIDNIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646.
&&
$$
TONIGHT/FRIDAY AND AVIATION/MARINE...MEB
FRIDAY NIGHT THROUGH THURSDAY...HENTZ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
306 PM CST THU FEB 14 2013
.SHORT TERM...
.TONIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM.
SURFACE LOW MOVES NORTHEAST FROM LAKE HURON TO SOUTHERN QUEBEC AS
HIGH PRESSURE BUILDS INTO THE NORTHERN AND CENTRAL PLAINS. DECENT
SHORTWAVE MOVING BY JUST TO OUR SOUTHWEST EARLY THIS EVENING.
HOWEVER...APPEARS PRECIP...OTHER THAN FLURRIES...WILL STICK TO OUR
SOUTHWEST. MODELS AGREE ON KEEPING MAIN AREA OF PRECIP TO THE
SOUTHWEST. ALSO...EXTRAPOLATION OF CURRENT SWATH OF LIGHT SNOW
ASSOCIATED WITH VORT MAX OVER CENTRAL IOWA WOULD SHOW MAIN AREA OF
PRECIP MOVING TO OUR SOUTHWEST.
LIGHT SNOW/FLURRIES WRAPPING AROUND THE LOW IN EAST CENTRAL
WISCONSIN WILL EXIT THIS EVENING AS THE LOW LIFTS NORTHEAST.
HOWEVER...KEPT FLURRY MENTION IN FOR THE NIGHT UNTIL DRY AIR
CURRENTLY IN MINNESOTA MOVES IN.
THE CLEARING AREA IN MINNESOTA HAS EXPANDED...AND MATCHES UP WELL
WITH THE RAP 850MB RH. WOULD HAVE THIS GETTING TO OUR WEST/NORTHWEST
AREA SOMETIME AROUND MIDNIGHT...PUTTING A HALT TO FLURRIES AS IT
MOVES IN. THIS COULD CREATE A PROBLEM FOR TONIGHT/S LOWS...COULD SEE
TEMPS REALLY DROP IF SIGNIFICANT CLEARING TAKES PLACE.
A WEAKER SHORTWAVE MOVES THROUGH TOMORROW AFTERNOON...SO EXPECTING
CLOUD COVER TO INCREASE FRIDAY MORNING WITH FLURRIES RETURNING.
THERE IS SOME PVA AND WAA BETWEEN 850 AND 700MB IN THE
AFTERNOON...BUT OVERALL NOT IMPRESSED BY Q VECTOR CONVERGENCE.
925MB COLD AIR ADVECTION TAKES HOLD TONIGHT. 925MB TEMPS DROP FROM
AROUND -3 TO -5C AT 00Z FRIDAY TO -11 TO -13C BY 12Z FRIDAY. NOT TOO
MUCH OF A REBOUND FOR FRIDAY EITHER. HIGHEST 925MB TEMPS ON FRIDAY
ABOUT -10 TO -12C. HOWEVER...MODELS HAVE BEEN A BIT COOL WHERE SNOW
PACK ISN/T AS SIGNIFICANT. PUT IN HIGHS IN THE 22-27F RANGE.
SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
SOUTHERN WISCONSIN IS ON THE WESTERN PERIPHERY OF THE LARGE UPPER
TROUGH AXIS. MODELS SHOW SHEARED CYCLONIC VORTICITY AXIS MOVING
ACROSS SOUTHERN WISCONSIN. SATURATED LOW LEVELS BELOW AN INVERSION
AROUND 5 THSD FT WITH STEEP LAPSE RATES BELOW THE INVERSION. SOME
FLURRY POTENTIAL.
SURFACE RIDGE AXIS THEN NUDGES INTO WESTERN WISCONSIN BY THE END
OF THE DAY.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE...MEDIUM
TO HIGH
THE HIGH PRESSURE RIDGE SHIFTS EAST OF AREA WITH THE PLAINS
TROUGH APPROACHING. WARM ADVECTION UNDERWAY THROUGH THIS PERIOD.
WARMEST 925 TEMPS ARRIVE SUNDAY NIGHT WITH READINGS RISING TO AT
OR ABOVE 0 CELSIUS. SHOULD BE A NON DIURNAL TEMPERATURE TREND
WITH RISING TEMPERATURES.
MONDAY AND MONDAY NIGHT FORECAST CONFIDENCE...MEDIUM TO HIGH
THE MID/UPPER LEVEL UPPER TROUGH EXITS THE NORTHERN AND CENTRAL
PLAINS MONDAY AND MOVES INTO THE WESTERN GREAT LAKES MONDAY NIGHT.
A DECENT SURGE OF MOISTURE ADVECTS NORTHWARD AHEAD AND ALONG OF
THE LOWER LEVEL TROUGH. GFS/GEM AND ECMWF ALL SHOW PRECIP ARRIVING
MONDAY AFTERNOON AND MONDAY NIGHT. THICKNESS AND 850 MB
TEMPERATURES TREND TOWARD A MIX OR MAINLY SNOW EXCEPT FAR
SOUTHEAST. HOWEVER GFS FORECAST SOUNDING SHOW A WARM BOUNDARY
LAYER WHICH WOULD BRING MORE RAIN SOUTH AND RAIN/SNOW NORTH.
850/925 TEMPS THEN COLLAPSE DURING THE EVENING TRANSITIONING THE
PRECIPITATION TO SNOW.
.LONG TERM...
TUESDAY...FORECAST CONFIDENCE...MEDIUM
LINGERING CYCLONIC FLOW FROM THE DEPARTING MID LEVEL TROUGH SUGGESTS
KEEPING SOME SMALL POPS EAST FOR SNOW SHOWERS EARLY. THEN
PRONOUNCED DRYING. DECENT COLD ADVECTION EXPECTED BEHIND THE
STRENGTHENING LOW TO THE EAST/NORTHEAST.
WEDNESDAY...FORECAST CONFIDENCE...
BROAD CYCLONIC FLOW MOVES OFF AS A MID LEVEL RIDGE MOVES ACROSS
WISCONSIN. A RATHER STRONG CANADIAN HIGH WILL BE RIDGING SOUTHEAST
INTO THE AREA CONTINUING THE COLD TEMPERATURES.
THURSDAY...FORECAST CONFIDENCE...
STRONG SHORTWAVE OVER THE SOUTHWEST U.S. LIFTS NORTHEAST. MAIN
DIFFERENCE IS THAT THE 12Z ECMWF IS SOMEWHAT SLOWER AND FARTHER SOUTH.
GFS AND ECMWF BOTH BRING A STRONG LOW THAT WOULD FAVOR HEAVY SNOW
EVENTUALLY AFFECTING PORTIONS OF THE FORECAST AREA. THE ECMWF IS A
FAVORABLE TRACK FOR HEAVY SNOW OVER SOUTHEAST WISCONSIN...WITH THE
GFS A LITTLE FARTHER NORTH. HEAVY PRECIPITATION AMOUNTS ON BOTH
MODELS...WITH THE HEAVIEST ON THE GFS. THIS WILL BE A POTENTIAL
SNOWSTORM FOR LATER THURSDAY OR FRIDAY. PREFER THE SOMEWHAT SLOWER
ECMWF SO WILL NOT RAISE POPS FROM THE CONSENSUS GRIDS ON THURSDAY.
&&
.AVIATION/00Z TAFS/...
VFR CEILINGS WERE WEST OF ABOUT A JANESVILLE TO GREEN LAKE LINE
AROUND MID AFTERNOON. THINKING THESE CONDITIONS WILL SPREAD EAST
THIS EVENING AS THE SURFACE LOW MOVES EAST. NAM AND GFS SOUNDINGS
QUITE DIFFERENT IN TERMS OF CEILING HEIGHT. THINKING THE SOLUTION IS
SOMEWHERE IN THE MIDDLE BASED ON UPSTREAM OBS. LEANING TOWARDS VFR
CONDITIONS FOR THE MAJORITY OF THE NIGHT ONCE THE LOW MOVES EAST.
AREA OF DRY AIR OVER MINNESOTA HAS EXPANDED AND WILL LIKELY ARRIVE
IN OUR AREA AFTER MIDNIGHT. MORE CONFIDENT IN VFR CONDITIONS THEN.
COULD SEE SCATTERED FLURRIES TONIGHT UNTIL DRY AIR OVER MINNESOTA
MOVES IN. NOT EXPECTING ANY ACCUMULATION AT THE TAF SITES THOUGH.
CLOUDS WILL BUILD BACK IN FRIDAY MORNING AS ANOTHER SHORTWAVE
APPROACHES. THIS WILL BRING ANOTHER CHANCE FOR FLURRIES AS WELL. NOT
EXPECTING MUCH IF ANY ACCUMULATION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646.
&&
$$
TONIGHT/FRIDAY AND AVIATION/MARINE...MEB
FRIDAY NIGHT THROUGH THURSDAY...HENTZ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
237 PM CST THU FEB 14 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY
237 PM CST THU FEB 14 2013
MAIN FORECAST CONCERNS FOR THE SHORT TERM PERIOD:
1. TEMPERATURE AND CLOUD TRENDS THROUGHOUT
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING JUST OFF THE WEST COAST OF THE U.S. INTO BRITISH
COLUMBIA...WHILE TROUGHING COVERED MUCH OF EASTERN CANADA INTO THE
NORTHERN PLAINS AND WESTERN GREAT LAKES REGION. COMING THROUGH THE
TROUGH WAS A SHORTWAVE TROUGH APPROACHING THE SIOUX FALLS SOUTH
DAKOTA AREA...WHILE ANOTHER SHORTWAVE WAS SEEN IN CENTRAL
SASKATCHEWAN. THE SHORTWAVE THAT AFFECTED THE AREA LAST NIGHT INTO
THIS MORNING HAS MOVED OFF INTO LOWER MICHIGAN. RADAR IMAGERY SHOWED
A FEW RAIN/SNOW SHOWERS OVER MUCH OF WISCONSIN IN THE WAKE OF THE
LOWER MICHIGAN SHORTWAVE...DUE TO CYCLONIC FLOW OF LOW LEVEL
MOISTURE AND STEEP LOW LEVEL LAPSE RATES. TO THE WEST...RADAR ALSO
SHOWS A BAND OF RAIN/SNOW FROM CENTRAL SOUTH DAKOTA INTO NORTHWEST
IOWA...ASSOCIATED WITH THE SIOUX FALLS SHORTWAVE. NORTHWEST LOW
LEVEL WINDS BETWEEN THE TWO SHORTWAVES ARE GRADUALLY BRINGING IN
COLDER AIR. SOUNDINGS AT BIS...ABR...MPX AND INL ALL HAD 850MB TEMPS
DROP 3-4C BETWEEN 00Z AND 12Z...ALL BETWEEN -7 AND -12C AS OF 12Z.
SOME DRIER AIR WAS ALSO ACCOMPANYING THE NORTHWEST WINDS...NOTED BY
SATELLITE IMAGERY SHOWING CLEARING ACROSS NORTHERN MN.
TONIGHT THROUGH SATURDAY DEFINITELY ARE GOING TO BE COLDER THAN
AS OF LATE. THE SHORTWAVE OVER CENTRAL SASKATCHEWAN COMBINED WITH
ANOTHER SHORTWAVE CURRENTLY UP IN NORTHERN MANITOBA ARE GOING TO
DIG SOUTH...CARVING OUT A DEEP TROUGH OVER THE REGION BY 00Z
SATURDAY. 850MB TEMPS FALL AS THIS TROUGH FORMS...DROPPING TO -14
TO -18C BY 18Z FRIDAY AND -16 TO -20C BY 12Z SATURDAY PER MODEL
CONSENSUS. THOSE AT 12Z SATURDAY ARE 1.5 STANDARD DEVIATIONS BELOW
NORMAL. THE ONLY MITIGATING FACTOR TO THE COLD AIR WOULD BE THE
LACK OF SNOW OVER THE SOUTHWEST HALF OF THE FORECAST AREA...WHICH
IF SOME SUN CAN OCCUR WOULD REALLY HELP TO BOOST TEMPS UP GIVEN
THE CLIMBING SUN ANGLE NOW. GENERALLY FOLLOWED A BLEND OF THE
ECMWF AND 30 DAY BIAS CORRECTED GFS GRIDDED MOS GUIDANCE DATA
SINCE THEY HAVE BEEN DOING WELL AS OF LATE FOR HIGHS. LOWS ARE
HIGHLY CONTINGENT ON CLOUD COVER. AFTER SOME CLEARING TONIGHT...
MORE LOW TO MID CLOUDS MOVE IN FROM THE NORTHWEST FOR FRIDAY AND
FRIDAY NIGHT...ASSOCIATED WITH THAT SHORTWAVE DROPPING DOWN OUT OF
MANITOBA. THESE CLOUDS COMBINED WITH A NORTHWEST BREEZE SHOULD
HELP KEEP LOWS FROM BOTTOMING OUT...THUS A BLEND OF GUIDANCE FOR
LOWS SEEMS REASONABLE.
HANDLING CLOUD COVER SATURDAY COULD BE TRICKY. A RIDGE OF HIGH
PRESSURE IS PROGGED TO BUILD INTO THE WESTERN PORTIONS OF THE
FORECAST AREA. WILL FOLLOW THE GENERAL MODEL CONSENSUS OF THE LOW
CLOUDS BREAKING UP THROUGH THE DAY...DUE TO A COMBINATION OF THE LOW
LEVEL FLOW BECOMING ANTICYCLONIC AND DAYTIME MIXING. HOWEVER...IT IS
POSSIBLE THE CLOUDS COULD HANG ON FOR MUCH OF THE DAY. THIS COMBINED
WITH 850MB TEMPS STILL ONLY BETWEEN -14C WEST TO -20C EAST AT 18Z
WILL KEEP TEMPERATURES SEASONABLY COOL.
FOR SATURDAY NIGHT AND SUNDAY...A POTENT SHORTWAVE TROUGH IS PROGGED
TO DROP INTO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES...FORMING
TWO DISTINCT LOW PRESSURE AREAS ACROSS THE PLAINS DURING THE DAY
SUNDAY. A SOUTHERLY LOW LEVEL JET WILL DEVELOP AHEAD OF THESE TWO
LOWS...BRINGING UP WARMER AIR. AN INCREASE OF MID AND HIGH CLOUDS
ARE LIKELY TO ACCOMPANY THIS WARM ADVECTION. SO THE QUESTION FOR
LOWS SATURDAY NIGHT IS TIMING OF WHEN THE WARM ADVECTION STARTS UP
AND MID CLOUDS MOVE IN...VERSUS THE DEPARTURE TO THE EAST OF THE
SURFACE RIDGE. OUR WISCONSIN COUNTIES HAVE THE BEST SHOT OF
FAVORABLE RADIATIONAL COOLING CONDITIONS...THUS LEANED TOWARDS THE
COLDER SIDE OF GUIDANCE THERE. TEMPERATURES SHOULD RISE FROM LATE
SATURDAY NIGHT THROUGH SUNDAY AT MOST LOCATIONS AS SOUTHERLY WINDS
INCREASE. QUESTION ON SUNDAY IS HOW WARM DO WE GET...WITH 850MB
TEMPS THAT COULD APPROACH 0C NEAR CHARLES CITY IA BY 00Z MONDAY. IT
APPEARS SUNSHINE WILL BE ON THE INCREASE WEST OF THE MS RIVER AS THE
MID CLOUD LIFTS TO THE NORTH. GIVEN THE LACK OF SNOW OVER THE
SOUTHWEST HALF OF THE FORECAST AREA...LEANED MORE TOWARDS THE
CONSISTENTLY WARM ECMWF...BRINGING HIGHS AT LEAST TO THE MID 30S
AROUND CHARLES CITY.
PRECIPITATION WISE...MUCH OF THE SHORT TERM LOOKS DRY WITH RESPECT
TO REACHING 0.01" OF LIQUID EQUIVALENT IN ANY 12 HOUR PERIOD.
FLURRIES LOOK LIKELY...HOWEVER...FOR FRIDAY AND FRIDAY NIGHT OUT OF
THOSE LOW CLOUDS SINCE THEY EXIST WITHIN THE DENDRITIC GROWTH ZONE
AND HAVE WEAK LIFT FROM THE SHORTWAVE. PREVIOUS FORECAST MENTIONED
CONCERN THAT AS THE WARM ADVECTION STARTS UP SATURDAY NIGHT THAT WE
COULD SEE SOME SNOW FALL OUT OF THE ASSOCIATED MID CLOUD DECK. THAT
STILL REMAINS A CONCERN...THOUGH THINK FLURRIES WOULD BE THE MOST
THAT GETS PRODUCED. THEN AGAIN...THESE FLURRIES MIGHT BE ABSORBED BY
LOWER LEVEL DRY AIR. FOR NOW HAVE KEPT THE FORECAST DRY FOR SATURDAY
NIGHT AND SUNDAY.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
237 PM CST THU FEB 14 2013
MAIN CONCERNS FOR THE LONG TERM PERIOD...
1. TEMPERATURES AND PRECIPITATION POTENTIAL THROUGH MONDAY
2. BRIEF ARCTIC AIR SHOT FOR MID-WEEK
3. POTENTIAL FOR A WINTER STORM TO IMPACT THE AREA LATE IN THE WEEK
VERY GOOD MODEL AGREEMENT EXISTS AMONGST THE 14.12Z
ECMWF/GFS/CANADIAN/UKMET THROUGHOUT MUCH OF THE LONG TERM PERIOD.
FOR SUNDAY NIGHT INTO MONDAY...THE TROUGHING THAT WAS COMING ACROSS
THE NORTHERN ROCKIES EVOLVES BY MONDAY EVENING INTO A FULL
LONGITUDINAL TROUGH ACROSS THE CANADIAN AND U.S. PLAINS. THIS
TROUGHING EVENTUALLY PHASES TOGETHER AS IT CROSSES THE REGION AND
HEADS INTO THE GREAT LAKES FOR TUESDAY. PRIOR TO THE PHASING...A
REALLY STRONG PUSH OF WARM AIR COMES UP AT THE REGION WITH 850MB
TEMPS BETWEEN -2C AND +4C AT 12Z MONDAY. HAVE BOOSTED HIGH
TEMPERATURES FOR MONDAY AS A RESULT...THOUGH COULD BE EVEN HIGHER AS
NOTED BY THE 14.12Z ECMWF. ALSO...MODELS CONTINUE TO TREND
FARTHER WEST WITH THE SOUTHERN LOW COMING OUT OF THE SOUTHERN
PLAINS. AS SUCH...NOW ABOUT THE EASTERN TWO THIRDS OF THE AREA IS
AFFECTED BY LIGHT PRECIPITATION FOR MONDAY AFTERNOON AND EVENING.
THUS...HAVE EXPANDED LOW PRECIPITATION CHANCES FARTHER WEST AND
RAISED THEM 5-10 PERCENT. IF TRENDS CONTINUE...THESE CHANCES WILL
NEED TO BE RAISED MORE. WITH THE WARMER TEMPERATURES TOO...MIXING
WITH OR CHANGING TO RAIN IS AN ISSUE AS WELL.
AS THE PHASED TROUGH FORMS OVER THE AREA MONDAY NIGHT AND TUESDAY...
ARCTIC AIR FLOWS INTO THE REGION. 850MB TEMPS PLUMMET TO -12 TO -14C
BY 12Z TUESDAY AND -14 TO -20C BY 12Z WEDNESDAY. THUS...A MUCH
COOLER PERIOD IS ON TAP AGAIN. CANADIAN HIGH PRESSURE BUILDING DOWN
INTO THE NORTHERN PLAINS...IN THE WAKE OF THE PHASED TROUGH...WILL
PROVIDE FOR BLUSTERY CONDITIONS. WIND CHILLS RIGHT NOW LOOK TO STAY
JUST ABOVE ADVISORY CRITERIA...BOTTOMING OUT AT MOST IN THE -15 TO
-20F RANGE WEDNESDAY MORNING.
LASTLY...ABOUT THE POTENTIAL WINTER STORM LATE IN THE WEEK. THERE IS
SURPRISINGLY CONSISTENT AND GOOD MODEL AGREEMENT AMONGST THE
ECMWF...GFS AND THEIR RESPECTIVE ENSEMBLES OF A DEEP TROUGH FORMING
OVER THE WESTERN U.S. ON WEDNESDAY. AS THIS TROUGH HEADS EAST
TOWARDS THE PLAINS...A DEEP LOW PRESSURE AREA DEVELOPS OVER THE
CENTRAL PLAINS BY THURSDAY MORNING. THERE ARE A FEW QUESTIONS FROM
HERE ON...WHICH MAY TAKE AT LEAST A FEW MORE DAYS TO ANSWER:
1. TIMING AND STRENGTH AS USUAL
2. HOW QUICK DOES THE PRECIPITATION SPREAD INTO THE AREA IF IT
INDEED AFFECTS US
3. HOW MUCH PRECIPITATION WOULD OCCUR
4. DEPENDING ON HOW MUCH THE SYSTEM WRAPS UP...MAY HAVE TO DEAL WITH
PRECIPITATION TYPE ISSUES
FOR NOW HAVE STAYED WITH A CONSENSUS APPROACH...WHICH BY THURSDAY
NIGHT YIELDS 50-60 PERCENT CHANCES OF PRECIPITATION REGION-WIDE. ALL
PRECIPITATION RIGHT NOW LOOKS TO FALL AS SNOW...WHICH COULD BE
SIGNIFICANT. SINCE THE STORM IS VERY FAR OUT IN THE FORECAST AND
JUST BEYOND THE CURRENT HWO PERIOD...HAVE KEPT THE MENTION OF THE
STORM TO THIS DISCUSSION ONLY. HOWEVER...IF TRENDS ON THIS SYSTEM
CONTINUE...LATER SHIFTS WILL NEED TO MENTION THE STORM IN THE HWO
AND IN OTHER DECISION SUPPORT SERVICES.
&&
.AVIATION...THROUGH 18Z FRIDAY
1210 PM CST THU FEB 14 2013
WHILE VISIBILITIES NOT EXPECTED TO HAMPER AVIATION...CEILINGS WILL
BE TROUBLESOME WITH ONE SHORT WAVE TROUGH PASSING BY TO THE
SOUTHWEST AND A MIX OF STRATUS AND MID LEVEL CLOUDS UPSTREAM.
COMBINATION OF PASSING SHORT WAVE AND CYCLONIC FLOW FROM PREVIOUS
SYSTEM...CLOUDS WILL FILL IN QUITE A BIT REST OF TODAY WITH GENERAL
VFR AND LIMITED MVFR CEILINGS ANTICIPATED. COULD ALSO SEE SOME SNOW
SHOWERS BUT AGAIN...DO NOT EXPECT BIG IMPACT THERE.
SUBSIDENCE TO THE NORTH SHOULD PRODUCE PERIOD TONIGHT OF CLEAR TO
SCATTERED DECKS BEFORE MAINLY MID LEVEL CLOUDS ADVECT BACK IN EARLY
FRIDAY. STEEP LAPSE RATES SUGGEST STRATUS AND FLURRIES COULD
DOMINATE ON FRIDAY AS WELL BUT MAINLY VFR CONDITIONS SHOULD PREVAIL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
237 PM CST THU FEB 14 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....SHEA
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1126 PM CST WED FEB 13 2013
.SHORT TERM...TONIGHT INTO THURSDAY
827 PM CST WED FEB 13 2013
827 PM BRIEF UPDATE...14.00Z NAM SHIFTED THE NARROW FRONTOGENESIS
BAND ON THE NORTH SIDE OF THE SURFACE LOW SLIGHTLY SOUTH...
IMPACTING MOSTLY CLARK NOW. 14.23Z HRRR ALSO HAS A VERY SLIGHT
TREND SOUTH. GIVEN THE UNCERTAINTY ON WHERE EXACTLY THIS BAND WILL
SET UP...HAVE DECLINED TO UPGRADE TO A WARNING. IN GENERAL...SNOW
AMOUNTS SHOULD TOTAL IN THE 3-6 INCH RANGE...HIGHEST MOST LIKELY
OCCURRING IN NORTHERN CLARK COUNTY. DEFINITELY HEAVIEST SNOW
BETWEEN MIDNIGHT AND 8 AM REMAINS ON TARGET.
724 PM BRIEF UPDATE...IN ADDITION TO THE UPDATE INFORMATION BELOW
MADE AT 555 PM...NOTICED THAT BLENDING THE QPF FOR 06-12Z THURSDAY
FROM THE PREFERRED MODEL GROUP RESULTS IN A NARROW BAND AROUND
HIGHWAY 29 INTO SOUTHERN TAYLOR COUNTY UPWARDS OF 0.30 INCHES.
SNOW TO WATER RATIOS...GIVEN ONLY A 75 MB DEEP DENDRITIC GROWTH
ZONE PROGGED...SHOULD END UP MOSTLY IN THAT 13-15 TO 1 RANGE...
RESULTING IN A 6 HOUR PERIOD OF 3-5 INCHES OF SNOW. WE COULD
APPROACH LOW END WARNING CRITERIA IN THIS BAND. AFTER
COLLABORATION WITH GRB...WILL STICK WITH THE ADVISORY FOR NOW
PENDING THE 14.00Z NAM. TOUGHEST PART WITH A WARNING WOULD BE
GRABBING THE RIGHT AREA SINCE THIS WILL BE A NARROW BAND.
MAIN UPDATE AT 555 PM...
TWO SHORTWAVES ARE EVIDENT ON WATER VAPOR...ONE OVER WEST CENTRAL
MINNESOTA AND THE OTHER IN SOUTHERN SASKATCHEWAN. THESE ARE BOTH
DROPPING SOUTHEAST THROUGH THE NORTHWEST FLOW ALOFT. WITH THE WEST
CENTRAL MINNESOTA SHORTWAVE...TWO AREAS OF RADAR RETURNS ARE
PRESENT. THE FIRST ASSOCIATED WITH WARM ADVECTION EXTENDS FROM
JUST WEST OF THE TWIN CITIES SOUTH INTO NORTH CENTRAL IOWA. SO
FAR...OBSERVATIONS HAVE NOT SHOWN MUCH PRECIPITATION FALLING FROM
THIS BAND...SUGGESTING A LOW LEVEL DRY AIR ISSUE ABSORBING THE
PRECIPITATION. THE SECOND BAND ON THE OTHER HAND IS PRODUCING
SNOW...WHICH STRETCHED FROM JAMESTOWN NORTH DAKOTA TO ST CLOUD MN.
THIS BAND IS ASSOCIATED WITH LOW TO MID-LEVEL FRONTOGENESIS ON THE
NORTH SIDE OF THE SHORTWAVE TRACK. MANY VISIBILITY REPORTS OF A
1/2 MILE TOO IN THE SNOW.
13.20Z HRRR...13.18Z NAM...13.12Z HIRES-NMM AND REGIONAL CANADIAN
ALL HAVE BEEN HANDLING CURRENT RADAR TRENDS WELL WITH THE WEST
CENTRAL MINNESOTA SHORTWAVE. THE IDEA IS THAT THE WARM ADVECTION
BAND OF RADAR RETURNS WILL MOVE ACROSS THE SOUTHERN TWO-THIRDS OF
THE FORECAST AREA BETWEEN 02-08Z...LASTING FOR A COUPLE OF HOURS
AT ANY ONE LOCATION...FOLLOWED BY A DRY SLOT. GIVEN LACK OF
PRECIPITATION OBSERVED UPSTREAM...AM UNCERTAIN WHETHER WE WILL SEE
ANY PRECIPITATION FROM THIS BAND. HAVE TRENDED PRECIPITATION
CHANCES TOWARDS THE ABOVE MODEL GROUP IDEA AND MAY HAVE TO DRY
THINGS OUT MORE. IF PRECIPITATION OCCURS...IT NOW LOOKS MORE LIKE
A RAIN/SNOW ISSUE GIVEN THE WARM LAYER IS AT THE SURFACE. MODELS
HAD SUGGESTED A WARM LAYER RIGHT ABOVE THE SURFACE...BUT THIS
SEEMS OVERDONE BECAUSE THEY ARE NOT HANDLING THE TEMPERATURES WELL
ACROSS THE SLOWLY DIMINISHING SNOWPACK. AS SUCH...REMOVED THE
FREEZING RAIN/SLEET POTENTIAL. THE NORTHERN BAND IS STILL ON TRACK
TO IMPACT THE ADVISORY AREA AFTER 03Z. WOULD NOT BE SURPRISED TO
SEE VISIBILITIES QUICKLY DROP TO 1 MILE OR LESS SEEING THE 1/2
MILE UPSTREAM. THE NORTHERN BAND IS THEN SUGGESTED TO WRAP
BACKWARDS AND TRACK SOUTHEAST ACROSS MUCH OF THE FORECAST AREA
BETWEEN 09-16Z...WELL TRENDED FROM THE PREVIOUS FORECAST. AM
CONCERNED A LITTLE BIT ABOUT HOW MUCH QPF COULD OCCUR IN TAYLOR
AND CLARK COUNTIES WHERE THE ADVISORY IS POSTED. THE 13.12Z
HIRES-NMM IS ABOUT 0.10 OF AN INCH HIGHER THAN CURRENTLY FORECAST
FOR 06-12Z TONIGHT...WITH THE HRRR SUGGESTING SIMILAR POTENTIAL.
HAVE RAISED QPF SLIGHTLY BUT MAY NEED TO RAISE MORE. SNOWFALL
AMOUNTS UP TO 5 INCHES NOW SEEM POSSIBLE...STILL BELOW WARNING
CRITERIA AT THIS POINT.
FOR THURSDAY...THERE LOOKS TO BE A BREAK BETWEEN THE CURRENT
SHORTWAVE TRACKING THROUGH TONIGHT INTO TOMORROW MORNING AND THEN
THE ONE APPROACHING FROM SOUTHERN SASKATCHEWAN. HIRES MODELS /ARW
AND NMM/ TRACK THE SHORTWAVE INTO IOWA...WITH ITS LOW TO MID LEVEL
FRONTOGENESIS BAND IMPACTING FAR WESTERN PORTIONS OF SOUTHEAST
MINNESOTA AND INTO NORTHEAST IOWA...PRIMARILY BETWEEN 21-03Z. MAY
MAKE SOME ADJUSTMENTS TO PRECIPITATION CHANCES TO ACCOUNT FOR THE
TRACK OF THIS FRONTOGENESIS BAND.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
236 PM CST WED FEB 13 2013
13.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY NIGHT
THROUGH MONDAY. UPPER LEVEL RIDGE WILL MOVE OVER THE REGION ON
SUNDAY. SOUTHERLY FLOW AT THE SURFACE WILL INCREASE AHEAD OF A
TROUGH RACING ACROSS THE NORTHERN ROCKIES. WILL HAVE TO KEEP A CLOSE
EYE ON TEMPERATURES ON SUNDAY. THE LATEST ECMWF WARMS HIGHS INTO
THE UPPER 30S TO LOWER 40S SOUTH OF INTERSTATE 90 AND THIS SEEMS
REASONABLE. THE NEXT TROUGH IS EXPECTED TO MOVE ACROSS THE REGION ON
MONDAY BUT THE FORECAST AREA LOOKS TO BE SPLIT BETWEEN A SOUTHERN
STREAM WAVE MOVING UP THE OHIO RIVER VALLEY AND A NORTHERN STREAM
WAVE MOVING ACROSS SOUTHERN ONTARIO/NORTHERN LAKE SUPERIOR. A COLD
FRONT WILL MOVE ACROSS THE AREA MONDAY NIGHT INTO TUESDAY WITH
COOLER AIR ARRIVING ON TUESDAY. HIGHS ARE EXPECTED TO FALL INTO THE
TEENS TO LOWER 20S. COOL HIGH PRESSURE WILL REMAIN OVERHEAD INTO
WEDNESDAY WITH MAINLY DRY AND QUIET WEATHER EXPECTED.
&&
.AVIATION...THROUGH 06Z FRIDAY
1126 PM CST WED FEB 13 2013
BAND OF RAIN AND SNOW HAS MOVED THROUGH KRST AND HAS ALMOST
CLEARED KLSE...ASSOCIATED WITH A WARM FRONT. LOWER MVFR CEILINGS
ARE COMING IN BEHIND THIS BAND. TO THE NORTHWEST...ANOTHER AREA OF
PRECIPITATION...IN THIS CASE ALL SNOW...WAS PRESENT FROM NEAR
MANKATO TO THE TWIN CITIES AS OF 05Z. THIS IS RIGHT BEHIND A COLD
FRONT. EXPECT THE BAND OF SNOW TO MOVE THROUGH THE TAF SITES
BETWEEN 09-15Z...WITH A FEW HOURS OF IFR VISIBILITIES AND PERHAPS
EVEN IFR CEILINGS OCCURRING. KLSE LOOKS TO END UP A LITTLE CLOSER
TO THE HEAVIER SNOW...THUS HAVE INCLUDED A TEMPO GROUP FOR LIFR
VISIBILITIES...IN AGREEMENT WITH WHAT WAS PRESENT AT MSP. SNOWFALL
ACCUMULATIONS LOOK LIGHT...GENERALLY AN INCH OR LESS. MAINLY VFR
VISIBILITIES...MVFR CEILINGS AND FLURRIES ARE ANTICIPATED AFTER 15
OR 16Z...AS CYCLONIC FLOW PERSISTS IN THE WAKE OF THE LOW PRESSURE
SYSTEM BRINGING THE CURRENT PRECIPITATION. SOME CONCERN THAT KRST
COULD PICK SOME ACCUMULATING SNOW LATE IN THE DAY...ASSOCIATED
WITH ANOTHER LOW PRESSURE SYSTEM DROPPING SOUTHEAST INTO IOWA.
HOWEVER...IT APPEARS THE BULK OF THE SNOW RIGHT NOW WILL STAY
SOUTH OF THE TAF SITES. NORTHWEST WINDS...WHICH COULD GUST UP TO
20 KT AT KRST...SHOULD HELP DRIVE IN DRIER AIR THURSDAY EVENING.
ANTICIPATING THIS DRIER AIR TO HELP SCATTER OUT THE CLOUDS AT
KRST. UNSURE IF THE DRIER AIR WILL GET INTO KLSE PRIOR TO
06Z...THUS HAVE HELD ONTO THE MVFR CEILING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
827 PM CST WED FEB 13 2013
WI...WINTER WEATHER ADVISORY UNTIL NOON CST THURSDAY FOR WIZ017-029.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...WETENKAMP
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1019 PM MST WED FEB 13 2013
.AVIATION...06Z TAFS
HAVE A COLD FRONT THAT IS FORECAST TO MOVE INTO THE PANHANDLE AND
SOUTHEAST WYOMING OVERNIGHT INTO THURSDAY MORNING. LATEST SREF AND
HRRR GUIDANCE FORECASTING A BAND OF IFR DEVELOPING OVER THE
CENTRAL PANHANDLE AROUND THE 10Z TIMEFRAME...PERSISTING THROUGH
LATE MORNING. CONFIDENCE MEDIUM IN THIS HAPPENING AS WE DO HAVE A
BAND OF SNOW IN THAT SAME GENERAL AREA RIGHT NOW. SO THIS GUIDANCE
IS SHOWING IT EXPANDING A LITTLE MORE LATER IN THE MORNING. WENT
AHEAD WITH SOME IFR CONDITIONS FOR KAIA...KSNY AND POSSIBLY KBFF.
01Z HRRR HAS THIS BAND JUST EAST OF KCYS AROUND 14Z...SO KEPT IT
OUT OF THE TAF FOR NOW. LATER SHIFT WILL NEED TO MONITOR CLOSELY.
OUT WEST FOR KRWL AND KLAR...THINK SNOW WILL DEVELOP AS THIS FRONT
MOVES THROUGH THAT AREA...BRINGING A PERIOD OF IFR CONDITIONS.
THIS WOULD BE MORE THE 12Z FORECAST CHALLENGE. BEHIND THE
FRONT...VERY STRONG NORTHWEST WINDS EXPECTED IN THE
PANHANDLE...WITH GUSTS TO 40KTS AT ALL LOCATIONS THROUGH 00Z.
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 606 PM MST WED FEB 13 2013/
UPDATE...
WINDS IN THE WARNED AREA...NAMELY BORDEAUX...ARLINGTON AND THE
SOUTHERN LARAMIE RANGE HAVE SHOWN STEADY DECREASES THE PAST COUPLE
HOURS. WENT AHEAD AND ALLOWED THE HIGH WIND WARNING TO EXPIRE ON
TIME AT 6 PM. GETTING SOME LIGHT SNOW BEING REPORTED IN THE
NORTHERN PANHANDLE AS WELL. RADAR IS SHOWING A BAND OF ENHANCED
SNOW SHOWERS ROUGHLY FROM ALLIANCE TO TORRINGTON TO WHEATLAND
MOVING SOUTH. WENT AHEAD AND ADDED SOME SMALL CHANCE POPS FURTHER
SOUTH THAN WHAT WE HAD PREVIOUS. UPDATES HAVE BEEN SENT.
CLAYCOMB
PREV DISCUSSION... /ISSUED 401 PM MST WED FEB 13 2013/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...
STILL GETTING OCCASIONAL WIND GUSTS TO 45-50 MPH ACROSS THE WIND
PRONE AREAS THIS AFTERNOON...HOWEVER THE TREND HAS BEEN DOWNWARD
SINCE LATE MORNING. WILL KEEP THE HIGH WIND WARNING GOING THROUGH 6
PM AS THE GFS SHOWS 700MB WINDS AROUND 45 KTS THROUGH 00Z THURS
AND THE 700MB CAG-CPR GRADIENT REMAINS ABOVE 40 METERS. STILL
EXPECTING WINDS TO CONSISTENTLY DROP BELOW 50 MPH BY LATE THIS
EVENING OVER THE WIND PRONE AREAS AS THE LLVL GRADIENT DECREASES
FURTHER AND THE LLVL WINDS HAVE A MORE NORTHWESTERLY ORIENTATION.
PRETTY STRONG SHORTWAVE MOVING SOUTHWARD OVER THE NORTHERN PLAINS
OVERNIGHT WILL DRIVE A COLD FRONT ACROSS THE AREA BY THURSDAY
MORNING. FOCUS FOR THE STRONGER WINDS WILL SHIFT EASTWARD OVER THE
PANHANDLE ZONES BY THURSDAY MORNING. DECIDED TO ISSUE A WIND
ADVISORY FROM THURSDAY MORNING THROUGH THE AFTERNOON BASED ON SOME
FAVORABLE INGREDIENTS. THE GFS SHOWS NORTHWESTERLY 700MB FLOW
AROUND 50 KTS BY 18Z THURS ALONG WITH GOOD SUBSIDENCE (COLD AIR
ADVECTION) BEHIND THE SHORTWAVE. IN ADDITION...LLVL LAPSE RATES
ARE EXCELLENT BY LATE MORNING OVER THE PANHANDLE WITH 35-40 KTS OF
UNIDIRECTIONAL FLOW IN THE MIXED LAYER. SINCE SEVERAL SITES IN THE
PANHANDLE WERE CLOSE TO HITTING 45 MPH GUSTS THIS
AFTERNOON...BELIEVE THAT GUSTS TO 45-50 MPH WILL DEFINITELY BE
POSSIBLE TOMORROW.
THERE WILL BE A GOOD AMOUNT OF 700-500MB MOISTURE IN THE
NORTHWESTERLY FLOW THURSDAY MORNING THROUGH FRIDAY MORNING...WITH
THE AXIS OVER SOUTHEAST WY. THE GFS AND THE NAM SHOW WEAK MIDLEVEL
FRONTOGENESIS ACROSS EXTREME SOUTHEAST WYOMING/NEBRASKA PANHANDLE
ON THURS AFTN. HIGHEST QPF ON THURS AFTN IS GENERALLY WEST OF THE
LARAMIE RANGE (TO THE WEST OF THE FRONTOGENESIS AXIS)...SO COULD
SEE SOME ENHANCEMENT IN SNOWFALL RATES AT THAT TIME.
HOWEVER...SNOWFALL AMOUNTS ACROSS THE LOWER ELEVATIONS WILL
GENERALLY BE LESS THAN AN INCH THROUGH FRIDAY MORNING. DO HAVE
SNOWFALL AMOUNTS OF 6 TO 9 INCHES IN THE SIERRA MADRE AND SNOWY
RANGES FROM TONIGHT THROUGH FRIDAY MORNING. SINCE SNOWFALL RATES
WILL BE LIGHT WITH THIS EVENT...AND BLOWING SNOW WILL NOT BE MUCH
OF A PROBLEM OVER SOUTHEAST WY...DECIDED TO HOLD OFF ON ISSUING A
MARGINAL WINTER WEATHER ADVISORY. THIS IS ONE OF THOSE HIGHER
ACCUMULATION BUT LONG DURATION EVENTS OVER THE MTNS. WILL
CONTINUE TO HIGHLIGHT THE SNOWFALL ACCUMULATIONS IN THE MTNS IN
THE HWO AND SPS. TEMPS WILL OBVIOUSLY BE COLDER ON THURS BEHIND
THE FROPA AS 700MB TEMPS DROP DOWN TO -14C.
A FINAL SHORTWAVE DIVES DOWN INTO THE NORTHERN AND CENTRAL PLAINS
ON FRIDAY BEFORE THE LONG WAVE TROUGH QUICKLY SHIFTS EASTWARD.
THIS SHORTWAVE WILL MAINTAIN THE COLD NORTHWESTERLY FLOW OVER THE
REGION FOR ONE MORE DAY. ANOTHER SLUG OF 700-500MB MOISTURE MOVES
OVER THE AREA FROM FRIDAY MORNING INTO THE AFTN BEFORE THE
MIDLEVELS DRY OUT. A LIGHT QPF EVENT COULD BE IN STORE WITH THIS
SHORTWAVE...WITH SNOW AMOUNTS LIMITED BY WEAK DYNAMICS AND QUITE
PROGRESSIVE NATURE OF THE SYSTEM.
LONG TERM...SATURDAY THROUGH WEDNESDAY....
MILD AND MAINLY DRY WEATHER EXPECTED SATURDAY AND SUNDAY AS UPPER
RIDGE TRANSLATES ACROSS THE REGION. SOME WINDINESS WILL OCCUR
MAINLY SATURDAY AS SFC LEE TROF SETS UP OVER THE HIGH PLAINS
INCREASING THE SFC PRESSURE GRADIENT. BY LATE SUNDAY UPPER
SHORTWAVE WILL MOVE INTO THE NRN ROCKIES AND PROCEED INTO THE
NORTHERN PLAINS AND CENTRAL ROCKIES SUNDAY NIGHT INTO MONDAY.
THIS WILL PUSH NEXT COLD FRONT ACROSS THE AREA LATE SUNDAY AS WELL
AS BRING SOME SNOW OR SNOW SHOWERS. PROGRESSIVE UPPER FLOW ALLOWS
NEXT UPPER RIDGE TO PASS ACROSS MONDAY NIGHT WHILE NEXT MORE
SIGNIFICANT UPPER TROF MOVES ONSHORE ALONG THE WEST COAST. WARMER
AGAIN TUESDAY THEN EFFECTS OF THIS NEXT UPPER TROF SHOULD ARRIVE
WEDS WITH SNOW AND SNOW SHOWERS SPREADING OVER MAINLY THE WY
PORTION OF THE CWA ALONG WITH COOLER TEMPERATURES. WILL HAVE TO
WATCH THIS SYSTEM CLOSELY AS IT HAS SOME POTENTIAL TO BE
SIGNIFICANT.
&&
FIRE WEATHER...
MINIMAL FIRE WEATHER CONCERNS THROUGH FRIDAY. TEMPERATURES WILL BE
AROUND 10-15 DEGREES BELOW NORMAL ON THURSDAY AND FRIDAY. MINIMUM
AFTERNOON HUMIDITIES WILL GENERALLY BE ABOVE 40 PERCENT. THERE
WILL BE ISOLATED TO WIDELY SCATTERED SNOW SHOWERS THURSDAY MORNING
THROUGH FRIDAY MORNING OVER THE PLAINS...HOWEVER ACCUMULATIONS ARE
EXPECTED TO BE LESS THAN AN INCH.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...WIND ADVISORY FROM 8 AM THURSDAY TO 4 PM THURSDAY FOR NEZ002-
NEZ003-NEZ019-NEZ020-NEZ021-NEZ054-NEZ055-NEZ095-NEZ096.
&&
$$
SHORT TERM/FIRE WEATHER...FINCH
LONG TERM/AVIATION...RE
AREA FORECAST DISCUSSION
NWS ALBANY NY
113 AM EST SAT FEB 16 2013
.SYNOPSIS...
TONIGHT THROUGH SATURDAY NIGHT...WAVES OF LOW PRESSURE WILL MOVE
FROM THE MID ATLANTIC COAST TO WELL SOUTH AND EAST OF LONG ISLAND
BRINGING A LIGHT SNOWFALL FROM THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND. THE WAVES OF LOW PRESSURE WILL MERGE INTO A POWERFUL
STORM EAST OF THE GULF OF MAINE BRINGING BLUSTERY AND COLD
CONDITIONS FOR SUNDAY...BUT WITH THE BULK OF SNOWFALL OCCURRING
ACROSS COASTAL NEW ENGLAND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1230 PM EST...HAD TO MAKE SOME CHANGES NAMELY TO REFLECT THE
FACT THAT LIGHT SNOW DEVELOPED MORE QUICKLY THAN ORIGINALLY THOUGHT
OVER THE CAPITAL DISTRICT AND EVEN POINTS TO THE SOUTH. INCREASED
POPS TO HIGH LIKELY OR EVEN CATEGORICAL IN THESE AREAS SINCE INDEED
IT IS EITHER SNOW (OR RAINING SOUTH WHERE SURFACE TEMPERATURES WERE
TOO WARM TO SUPPORT SNOW YET). HOWEVER...WITH EVAPORATIVE COOLING WE
ARE CONFIDENT THAT THE RAIN WILL CHANGE TO SNOW IN THESE AREAS IN A
FEW HOURS.
OTHERWISE...JUST RE-TOOLED THE HOURLY GRIDS...ESPECIALLY
TEMPERATURES WHICH HAD DROPPED THE FASTEST THE SNOW WAS FALLING.
HOWEVER...OVERNIGHT LOWS STILL LOOK REASONABLE SO LEFT THEM ALONE.
THE LATEST RUC13 INDICATES AN AREA OF ENHANCED 850-700 MB
FRONTOGENETICAL FORCING ACROSS EASTERN PA EXTENDING INTO EASTERN
NYS...AND THIS AREA HAS EXPANDED NE. IT WILL THEN GRADUALLY SHIFT
EASTWARD A FEW HOURS AFTER MIDNIGHT.
FOR AREAS MAINLY S AND E OF ALBANY...THE PRECIPITATION AREA SHOULD
CONTINUE EXPANDING N AND E THROUGH AROUND 2 AM...BEFORE SHIFTING
SLOWLY EAST. BOUNDARY LAYER TEMPS REMAIN SOMEWHAT MILD...AND
SHOULD ALLOW FOR PRECIP TO BEGIN MAINLY AS LIGHT RAIN IN VALLEY
AREAS...WITH A RAIN/SNOW MIX ACROSS HIGHER ELEVATIONS.
HOWEVER...AFTER ABOUT 1-2 HOURS OF EVAPORATIONAL COOLING...EVEN
VALLEY AREAS SHOULD TRANSITION TO SNOW AROUND OR JUST AFTER
MIDNIGHT...WITH HIGHER ELEVATIONS CHANGING OVER MORE QUICKLY.
STILL EXPECT SNOWFALL TOTALS OF AROUND AN INCH FOR HUDSON VALLEY
LOCATIONS...WITH PERHAPS 1-3 INCHES FOR AREAS E OF THE HUDSON
RIVER INTO NW CT...AND EASTERN DUTCHESS CO. FURTHER N AND
W...STILL EXPECT MAINLY UNDER AN INCH...WITH PERHAPS 1-2 INCHES
ACROSS PORTIONS OF THE SOUTHERN BERKSHIRES. THE GREATER CAPITAL
DISTRICT AND POINTS TO THE NORTH WILL RECEIVE A COATING TO AN INCH
OF SNOWFALL.
AS FOR MIN TEMPS...GIVEN THE ABUNDANT CLOUD COVER OVERNIGHT...AND
THE FACT THAT CURRENT TEMPS ARE RUNNING A BIT WARMER THAN PREVIOUS
GUIDANCE SUGGESTED...HAVE RAISED MINS BY ABOUT 1-3 DEGREES IN MOST
AREAS...WITH MID/UPPER 20S EXPECTED WITHIN THE HUDSON RIVER VALLEY
FROM ALBANY SOUTH...AND TEENS TO LOWER/MID 20S ACROSS THE SOUTHERN
ADIRONDACKS. ELSEWHERE...EXPECT MAINLY LOWER/MID 20S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
ANOTHER WAVE OF LOW PRESSURE MERGES OFFSHORE NEW ENGLAND AND RAPID
STRENGTHENING OF THE SYSTEM SHOULD OCCUR AS AN UPPER CUT OFF LOW
INTERACTS WITH THE SYSTEM. CONSENSUS FROM GUIDANCE AND ENSEMBLES
SUGGESTS THE STORM TRACKS TOO FAR EAST TO REALLY IMPACT OUR
FORECAST AREA...WITH PERHAPS JUST SOME ADDITIONAL LIGHT
ACCUMULATION FOR WESTERN NEW ENGLAND SATURDAY NIGHT AND EARLY
SUNDAY MORNING. STILL THERE SHOULD BE ENOUGH CLOUD COVER AND LIGHT
WINDS TO KEEP HIGH TEMPERATURES A LITTLE BELOW NORMAL...IN THE
LOWER TO MID 30S...20S IN HIGHER TERRAIN.
AS THE STORM RAPIDLY STRENGTHENS AND TRACKS INTO SOUTHEASTERN
CANADA...THE MEAN UPPER TROUGH AXIS BUILDS EAST AND VERY COLD AIR
SPILLS EAST INTO OUR REGION. THE TIGHT PRESSURE GRADIENT AROUND
THE STRONG LOW PRESSURE SHOULD SUPPORT STRONG WINDS THROUGHOUT THE
NORTHEASTERN U.S. MAKING FOR A NOTICEABLY COLD DAY SUNDAY. THERE
COULD BE WIND CHILL ISSUES AND MAYBE BORDERING ON WIND ADVISORY
WIND SPEEDS IN SOME AREAS. HIGHS SUNDAY IN THE LOWER TO MID
20S...SOME UPPER 20S SOUTHERN AREAS AND TEENS IN HIGHER TERRAIN.
THE STORM IS PREDICTED TO BE SLOW TO EXIT...AND THE WINDS MAY
DIMINISH ONLY GRADUALLY SUNDAY NIGHT INTO MONDAY. AGAIN...THERE
MAY BE SOME WIND CHILL ISSUES IN SOME AREAS...ESPECIALLY
SUNDAY NIGHT. LOWS SUNDAY NIGHT IN THE SINGLE NUMBERS TO LOWER
TEENS...AROUND OR JUST BELOW ZERO IN COLDER AREAS. HIGHS MONDAY IN
THE UPPER 20S TO LOWER 30S...LOWER 20S IN HIGHER TERRAIN.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MONDAY NIGHT...A RIDGE OF HIGH PRESSURE WILL SLIDE EASTWARD ACROSS
THE REGION...WHICH SHOULD BRING GENERALLY DRY CONDITIONS...WITH
DECREASING WIND. SOME HIGH/MID LEVEL CLOUDS MAY INCREASE LATE AT
NIGHT IN ADVANCE OF A SYSTEM APPROACHING FROM THE SOUTHWEST. EXPECT
ANOTHER COLD NIGHT...WITH MINS FALLING INTO THE SINGLE DIGITS ACROSS
NORTHERN AREAS...AND TEENS ELSEWHERE.
TUE-TUE NT...MODELS CONTINUE PREVIOUS TRENDS OF A MORE
PROGRESSIVE...AND FURTHER NORTH TRACK OF A SYSTEM DURING THIS TIME
PERIOD. STRONG WARM ADVECTION IN ADVANCE OF THIS SYSTEM SHOULD STILL
BRING A PERIOD OF PRECIPITATION TO THE REGION...MOST LIKELY TUE
AFTERNOON AND NIGHT...ALTHOUGH IT COULD START AS EARLY AS TUE
MORNING. FORECAST SOUNDINGS INDICATE MUCH OF THE REGION SHOULD BE
COLD ENOUGH TO SUPPORT MAINLY SNOW...ALTHOUGH BOUNDARY LAYER
TEMPS...AND SOME WARMING WITHIN THE 925-850 LAYER COULD ALLOW FOR
SOME RAIN TO MIX IN...ESP FOR AREAS SOUTH OF INTERSTATE 90 TUE
AFTERNOON. WILL INDICATE CHC POPS FOR THIS TIME PERIOD...WITH MAINLY
SNOW FOR NORTHERN AREAS...AND A RAIN/SNOW MIX FOR CENTRAL AND
SOUTHERN AREAS DEVELOPING BY TUE AFTERNOON...WITH PRECIPITATION
CHANGING TO SNOW ALL AREAS FOR TUE NT. MODELS HAVE TRENDED TOWARD
LESS OVERALL QPF...WITH THE 12Z/GEM REMAINING THE WETTER OUTLIER
ALLOWING FOR MORE SECONDARY COASTAL DEVELOPMENT FOR TUE NT. ASSUMING
THE 12Z/GFS/GEFS AND ECMWF PROVE CORRECT...IT APPEARS THAT THIS
EVENT SHOULD MAINLY COMPRISE OF LIGHT TO PERHAPS MODERATE
PRECIPITATION AMTS.
WED-THU NT...AS THE REMNANT UPPER LEVEL TROUGH PASSES NORTH OF THE
REGION WED AND WED EVENING...THE DEEP CYCLONIC FLOW WITHIN COLD AIR
ADVECTION SHOULD PROMOTE SCATTERED SNOW SHOWERS ACROSS MUCH OF THE
REGION...WITH THE MORE PERSISTENT SNOW SHOWERS ACROSS TRADITIONALLY
FAVORED AREAS OF THE WESTERN ADIRONDACKS...MOHAWK VALLEY...AND
POSSIBLY ACROSS THE SOUTHERN GREENS AND NORTHERN BERKSHIRES. THE
SNOW SHOWERS SHOULD DIMINISH IN AREAL COVERAGE LATE WED INTO WED
NT...FOLLOWED BY FAIR AND COLD CONDITIONS FOR THU INTO THU NT WITH
BELOW NORMAL TEMPS. SO...FOR MAX TEMPS...EXPECT LOWER/MID 30S IN
VALLEYS WED...WITH MAINLY 20S ACROSS HIGHER ELEVATIONS...WITH MAX
TEMPS A FEW DEGREES COLDER FOR THU. FOR MINS...EXPECT MAINLY 20S
ACROSS VALLEY REGIONS AND ADJACENT WESTERN NEW ENGLAND FOR WED AM
GIVEN CLOUDS AND SOME WIND...THEN TEENS IN LOWER ELEVATIONS...AND
SINGLE DIGITS ACROSS HIGHER ELEVATIONS FOR THU AM AND THU NT/FRI AM.
FRI...PREVIOUS RUNS OF VARIOUS GLOBAL DETERMINISTIC MODELS AND
ENSEMBLES HAVE INDICATED ANOTHER POTENTIAL STORM SYSTEM APPROACHING
THE REGION SOMETIME LATE FRI INTO NEXT WEEKEND. SEVERAL 12Z/15
MODELS HAVE TRENDED WEAKER...AND FURTHER SOUTH WITH ANY POTENTIAL
SYSTEM...GIVEN STRENGTHENING UPPER LEVEL RIDGING/BLOCKING ACROSS
CENTRAL/EASTERN CANADA. STILL A GREAT DEAL OF UNCERTAINTY AT THIS
TIME RANGE...SO HAVE MAINTAINED CHC POPS FOR FRI...WITH THERMAL
PROFILES SUGGESTING ALL SNOW. EXPECT MAX TEMPS TO POTENTIALLY REACH
30-35 IN LOWER ELEVATIONS...AND 20S FOR HIGHER TERRAIN.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS SOUTHERN PORTIONS OF
THE REGION LATE TONIGHT. THIS DISTURBANCE WILL BRING WIDESPREAD
LIGHT SNOW TO KPOU/KPSF UNTIL SHORTLY BEFORE SUNRISE...AND THROUGH
07Z/08Z AT KALB. AT KGFL LITTLE OR NO SNOW IS EXPECTED. ANY IFR
CONDITIONS AT KALB WILL END BY AROUND 07Z...BUT NOT UNTIL AROUND 10Z
AT KPOU AND KPSF. AT KGFL CONDITIONS WILL GET NO LOWER THAN MVFR.
AFTER 12Z...EXPECT VFR CONDITIONS AT ALL THE TAF SIDES FOR THE REST
OF THE TAF PERIOD ENDING AT 06Z SUNDAY.
WINDS WILL BE NORTH TO NORTHWEST AT LESS THAN 8 KTS THROUGH EARLY
SATURDAY MORNING...THEN INCREASE TO 8 TO 10 KTS BY LATE MORNING WITH
SOME GUSTS TO 15 KTS POSSIBLE...ESPECIALLY AT KALB. THESE WINDS WILL
PERSIST THROUGH 06Z SUNDAY.
OUTLOOK...
LATE SAT NT-MON NT...VFR. NO SIG WX.
TUE...MVFR/IFR TUE WITH MIXED PCPN.
TUE NITE-WED...MAINLY VFR. CHC MVFR -SHSN.
&&
.HYDROLOGY...
NO HYDROLOGY PROBLEMS ARE EXPECTED OVER THE NEXT FEW DAYS. SNOW
MELT WILL CONTINUE TO BE GRADUAL THROUGH SATURDAY WITH ABOVE
FREEZING TEMPERATURES DURING THE DAY...AND BELOW FREEZING AT
NIGHT. TEMPERATURES WILL BECOME COLDER FOR THE 2ND HALF OF THE
WEEKEND SLOWING...AND EVEN ENDING THE SNOWMELT.
THE PREDOMINANT PTYPE TODAY INTO THE MID WEEK WILL BE SNOW. THE
SYSTEMS DURING THAT TIME FRAME ARE EXPECTED TO ONLY PRODUCE LIGHT
SNOW AMOUNTS. THEREFORE...NO IMPACTS ARE EXPECTED ON THE ALY HSA
WATERWAYS.
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...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...NAS
NEAR TERM...HWJIV/KL
SHORT TERM...NAS
LONG TERM...KL
AVIATION...GJM
HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1225 AM EST SAT FEB 16 2013
.SYNOPSIS...
TONIGHT THROUGH SATURDAY NIGHT...WAVES OF LOW PRESSURE WILL MOVE
FROM THE MID ATLANTIC COAST TO WELL SOUTH AND EAST OF LONG ISLAND
BRINGING A LIGHT SNOWFALL FROM THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND. THE WAVES OF LOW PRESSURE WILL MERGE INTO A POWERFUL
STORM EAST OF THE GULF OF MAINE BRINGING BLUSTERY AND COLD
CONDITIONS FOR SUNDAY...BUT WITH THE BULK OF SNOWFALL OCCURRING
ACROSS COASTAL NEW ENGLAND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1230 PM EST...HAD TO MAKE SOME CHANGES NAMELY TO REFLECT THE
FACT THAT LIGHT SNOW DEVELOPED MORE QUICKLY THAN ORIGINALLY THOUGHT
OVER THE CAPITAL DISTRICT AND EVEN POINTS TO THE SOUTH. INCREASED
POPS TO HIGH LIKELY OR EVEN CATEGORICAL IN THESE AREAS SINCE INDEED
IT IS EITHER SNOW (OR RAINING SOUTH WHERE SURFACE TEMPERATURES WERE
TOO WARM TO SUPPORT SNOW YET). HOWEVER...WITH EVAPORATIVE COOLING WE
ARE CONFIDENT THAT THE RAIN WILL CHANGE TO SNOW IN THESE AREAS IN A
FEW HOURS.
OTHERWISE...JUST RE-TOOLED THE HOURLY GRIDS...ESPECIALLY
TEMPERATURES WHICH HAD DROPPED THE FASTEST THE SNOW WAS FALLING.
HOWEVER...OVERNIGHT LOWS STILL LOOK REASONABLE SO LEFT THEM ALONE.
THE LATEST RUC13 INDICATES AN AREA OF ENHANCED 850-700 MB
FRONTOGENETICAL FORCING ACROSS EASTERN PA EXTENDING INTO EASTERN
NYS...AND THIS AREA HAS EXPANDED NE. IT WILL THEN GRADUALLY SHIFT
EASTWARD A FEW HOURS AFTER MIDNIGHT.
FOR AREAS MAINLY S AND E OF ALBANY...THE PRECIPITATION AREA SHOULD
CONTINUE EXPANDING N AND E THROUGH AROUND 2 AM...BEFORE SHIFTING
SLOWLY EAST. BOUNDARY LAYER TEMPS REMAIN SOMEWHAT MILD...AND
SHOULD ALLOW FOR PRECIP TO BEGIN MAINLY AS LIGHT RAIN IN VALLEY
AREAS...WITH A RAIN/SNOW MIX ACROSS HIGHER ELEVATIONS.
HOWEVER...AFTER ABOUT 1-2 HOURS OF EVAPORATIONAL COOLING...EVEN
VALLEY AREAS SHOULD TRANSITION TO SNOW AROUND OR JUST AFTER
MIDNIGHT...WITH HIGHER ELEVATIONS CHANGING OVER MORE QUICKLY.
STILL EXPECT SNOWFALL TOTALS OF AROUND AN INCH FOR HUDSON VALLEY
LOCATIONS...WITH PERHAPS 1-3 INCHES FOR AREAS E OF THE HUDSON
RIVER INTO NW CT...AND EASTERN DUTCHESS CO. FURTHER N AND
W...STILL EXPECT MAINLY UNDER AN INCH...WITH PERHAPS 1-2 INCHES
ACROSS PORTIONS OF THE SOUTHERN BERKSHIRES. THE GREATER CAPITAL
DISTRICT AND POINTS TO THE NORTH WILL RECEIVE A COATING TO AN INCH
OF SNOWFALL.
AS FOR MIN TEMPS...GIVEN THE ABUNDANT CLOUD COVER OVERNIGHT...AND
THE FACT THAT CURRENT TEMPS ARE RUNNING A BIT WARMER THAN PREVIOUS
GUIDANCE SUGGESTED...HAVE RAISED MINS BY ABOUT 1-3 DEGREES IN MOST
AREAS...WITH MID/UPPER 20S EXPECTED WITHIN THE HUDSON RIVER VALLEY
FROM ALBANY SOUTH...AND TEENS TO LOWER/MID 20S ACROSS THE SOUTHERN
ADIRONDACKS. ELSEWHERE...EXPECT MAINLY LOWER/MID 20S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
ANOTHER WAVE OF LOW PRESSURE MERGES OFFSHORE NEW ENGLAND AND RAPID
STRENGTHENING OF THE SYSTEM SHOULD OCCUR AS AN UPPER CUT OFF LOW
INTERACTS WITH THE SYSTEM. CONSENSUS FROM GUIDANCE AND ENSEMBLES
SUGGESTS THE STORM TRACKS TOO FAR EAST TO REALLY IMPACT OUR
FORECAST AREA...WITH PERHAPS JUST SOME ADDITIONAL LIGHT
ACCUMULATION FOR WESTERN NEW ENGLAND SATURDAY NIGHT AND EARLY
SUNDAY MORNING. STILL THERE SHOULD BE ENOUGH CLOUD COVER AND LIGHT
WINDS TO KEEP HIGH TEMPERATURES A LITTLE BELOW NORMAL...IN THE
LOWER TO MID 30S...20S IN HIGHER TERRAIN.
AS THE STORM RAPIDLY STRENGTHENS AND TRACKS INTO SOUTHEASTERN
CANADA...THE MEAN UPPER TROUGH AXIS BUILDS EAST AND VERY COLD AIR
SPILLS EAST INTO OUR REGION. THE TIGHT PRESSURE GRADIENT AROUND
THE STRONG LOW PRESSURE SHOULD SUPPORT STRONG WINDS THROUGHOUT THE
NORTHEASTERN U.S. MAKING FOR A NOTICEABLY COLD DAY SUNDAY. THERE
COULD BE WIND CHILL ISSUES AND MAYBE BORDERING ON WIND ADVISORY
WIND SPEEDS IN SOME AREAS. HIGHS SUNDAY IN THE LOWER TO MID
20S...SOME UPPER 20S SOUTHERN AREAS AND TEENS IN HIGHER TERRAIN.
THE STORM IS PREDICTED TO BE SLOW TO EXIT...AND THE WINDS MAY
DIMINISH ONLY GRADUALLY SUNDAY NIGHT INTO MONDAY. AGAIN...THERE
MAY BE SOME WIND CHILL ISSUES IN SOME AREAS...ESPECIALLY
SUNDAY NIGHT. LOWS SUNDAY NIGHT IN THE SINGLE NUMBERS TO LOWER
TEENS...AROUND OR JUST BELOW ZERO IN COLDER AREAS. HIGHS MONDAY IN
THE UPPER 20S TO LOWER 30S...LOWER 20S IN HIGHER TERRAIN.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MONDAY NIGHT...A RIDGE OF HIGH PRESSURE WILL SLIDE EASTWARD ACROSS
THE REGION...WHICH SHOULD BRING GENERALLY DRY CONDITIONS...WITH
DECREASING WIND. SOME HIGH/MID LEVEL CLOUDS MAY INCREASE LATE AT
NIGHT IN ADVANCE OF A SYSTEM APPROACHING FROM THE SOUTHWEST. EXPECT
ANOTHER COLD NIGHT...WITH MINS FALLING INTO THE SINGLE DIGITS ACROSS
NORTHERN AREAS...AND TEENS ELSEWHERE.
TUE-TUE NT...MODELS CONTINUE PREVIOUS TRENDS OF A MORE
PROGRESSIVE...AND FURTHER NORTH TRACK OF A SYSTEM DURING THIS TIME
PERIOD. STRONG WARM ADVECTION IN ADVANCE OF THIS SYSTEM SHOULD STILL
BRING A PERIOD OF PRECIPITATION TO THE REGION...MOST LIKELY TUE
AFTERNOON AND NIGHT...ALTHOUGH IT COULD START AS EARLY AS TUE
MORNING. FORECAST SOUNDINGS INDICATE MUCH OF THE REGION SHOULD BE
COLD ENOUGH TO SUPPORT MAINLY SNOW...ALTHOUGH BOUNDARY LAYER
TEMPS...AND SOME WARMING WITHIN THE 925-850 LAYER COULD ALLOW FOR
SOME RAIN TO MIX IN...ESP FOR AREAS SOUTH OF INTERSTATE 90 TUE
AFTERNOON. WILL INDICATE CHC POPS FOR THIS TIME PERIOD...WITH MAINLY
SNOW FOR NORTHERN AREAS...AND A RAIN/SNOW MIX FOR CENTRAL AND
SOUTHERN AREAS DEVELOPING BY TUE AFTERNOON...WITH PRECIPITATION
CHANGING TO SNOW ALL AREAS FOR TUE NT. MODELS HAVE TRENDED TOWARD
LESS OVERALL QPF...WITH THE 12Z/GEM REMAINING THE WETTER OUTLIER
ALLOWING FOR MORE SECONDARY COASTAL DEVELOPMENT FOR TUE NT. ASSUMING
THE 12Z/GFS/GEFS AND ECMWF PROVE CORRECT...IT APPEARS THAT THIS
EVENT SHOULD MAINLY COMPRISE OF LIGHT TO PERHAPS MODERATE
PRECIPITATION AMTS.
WED-THU NT...AS THE REMNANT UPPER LEVEL TROUGH PASSES NORTH OF THE
REGION WED AND WED EVENING...THE DEEP CYCLONIC FLOW WITHIN COLD AIR
ADVECTION SHOULD PROMOTE SCATTERED SNOW SHOWERS ACROSS MUCH OF THE
REGION...WITH THE MORE PERSISTENT SNOW SHOWERS ACROSS TRADITIONALLY
FAVORED AREAS OF THE WESTERN ADIRONDACKS...MOHAWK VALLEY...AND
POSSIBLY ACROSS THE SOUTHERN GREENS AND NORTHERN BERKSHIRES. THE
SNOW SHOWERS SHOULD DIMINISH IN AREAL COVERAGE LATE WED INTO WED
NT...FOLLOWED BY FAIR AND COLD CONDITIONS FOR THU INTO THU NT WITH
BELOW NORMAL TEMPS. SO...FOR MAX TEMPS...EXPECT LOWER/MID 30S IN
VALLEYS WED...WITH MAINLY 20S ACROSS HIGHER ELEVATIONS...WITH MAX
TEMPS A FEW DEGREES COLDER FOR THU. FOR MINS...EXPECT MAINLY 20S
ACROSS VALLEY REGIONS AND ADJACENT WESTERN NEW ENGLAND FOR WED AM
GIVEN CLOUDS AND SOME WIND...THEN TEENS IN LOWER ELEVATIONS...AND
SINGLE DIGITS ACROSS HIGHER ELEVATIONS FOR THU AM AND THU NT/FRI AM.
FRI...PREVIOUS RUNS OF VARIOUS GLOBAL DETERMINISTIC MODELS AND
ENSEMBLES HAVE INDICATED ANOTHER POTENTIAL STORM SYSTEM APPROACHING
THE REGION SOMETIME LATE FRI INTO NEXT WEEKEND. SEVERAL 12Z/15
MODELS HAVE TRENDED WEAKER...AND FURTHER SOUTH WITH ANY POTENTIAL
SYSTEM...GIVEN STRENGTHENING UPPER LEVEL RIDGING/BLOCKING ACROSS
CENTRAL/EASTERN CANADA. STILL A GREAT DEAL OF UNCERTAINTY AT THIS
TIME RANGE...SO HAVE MAINTAINED CHC POPS FOR FRI...WITH THERMAL
PROFILES SUGGESTING ALL SNOW. EXPECT MAX TEMPS TO POTENTIALLY REACH
30-35 IN LOWER ELEVATIONS...AND 20S FOR HIGHER TERRAIN.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS SOUTHERN PORTIONS OF
THE REGION LATER TONIGHT. THIS DISTURBANCE WILL BRING WIDESPREAD
MID LEVEL CLOUDS OVERNIGHT...ALONG WITH A BRIEF PERIOD OF LIGHT
SNOW AT KPOU AND KPSF AFTER MIDNIGHT...WHICH COULD INITIALLY BE
MIXED WITH RAIN. KALB APPEARS TO BE ON THE NORTHWEST EDGE OF THE
DEVELOPING PRECIPITATION SHIELD...AND WILL ONLY INDICATE VCSH FOR
NOW UNLESS RADAR TRENDS INDICATE OTHERWISE LATER THIS EVENING.
IN AREAS WHERE THE SNOW DEVELOPS...A PERIOD OF MVFR OR POSSIBLE
IFR VSBYS AND CIGS WILL BE POSSIBLE BETWEEN 06Z-10Z/SAT.
ELSEWHERE...MAINLY VFR CONDITIONS ARE EXPECTED THROUGH DAYBREAK.
ON SATURDAY...AREAS OF MVFR CIGS COULD LINGER AT KPOU AND KPSF
THROUGH AROUND 15Z. OTHERWISE...VFR CONDITIONS ARE EXPECTED.
WINDS WILL BECOME MAINLY NORTHWEST OVERNIGHT AT GENERALLY LESS
THAN 7 T. WINDS WILL BECOME NORTH TO NORTHWEST ON SATURDAY AT
GENERALLY 5-10 KT...ALTHOUGH MAY BE A BIT STRONGER AT KALB AND
KPSF...ESP FROM LATE MORNING INTO THE AFTERNOON HOURS.
OUTLOOK...
SAT NT-TUE NT...VFR. NO SIG WX.
WED...VFR BCMG MVFR/IFR. -SN/-RA POSSIBLE IN AFTERNOON.
&&
.HYDROLOGY...
NO HYDROLOGY PROBLEMS ARE EXPECTED OVER THE NEXT FEW DAYS. SNOW
MELT WILL CONTINUE TO BE GRADUAL THROUGH SATURDAY WITH ABOVE
FREEZING TEMPERATURES DURING THE DAY...AND BELOW FREEZING AT
NIGHT. TEMPERATURES WILL BECOME COLDER FOR THE 2ND HALF OF THE
WEEKEND SLOWING...AND EVEN ENDING THE SNOWMELT.
THE PREDOMINANT PTYPE TODAY INTO THE MID WEEK WILL BE SNOW. THE
SYSTEMS DURING THAT TIME FRAME ARE EXPECTED TO ONLY PRODUCE LIGHT
SNOW AMOUNTS. THEREFORE...NO IMPACTS ARE EXPECTED ON THE ALY HSA
WATERWAYS.
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...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...NAS
NEAR TERM...HWJIV/KL
SHORT TERM...NAS
LONG TERM...KL
AVIATION...KL
HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1135 PM CST FRI FEB 15 2013
...UPDATE TO AVIATION...
.DISCUSSION...
12Z UPPER AIR DATA DEPICTED AT 130KT JET DIVING SOUTH OUT OF WESTERN
SASKATCHEWAN WITH WIDESPREAD 500MB TEMPS OF AROUND -40C OVER THE
NORTHERN PLAINS AND EASTERN CANADA. AN UPPER LEVEL TROF WAS MAKING
SOUTHWARD PROGRESS OUT OF THE WESTERN DAKOTAS IN RECENT HOURS PER
WATER VAPOR IMAGERY. WEAK RADAR RETURNS HAVE DEVELOPED OVER MUCH OF
NORTHERN KANSAS THOUGH DEWPOINT DEPRESSIONS AROUND 20F ARE LIKELY
KEEP MUCH OF THIS WEAK ACTIVITY FROM REACHING THE GROUND. 20Z
SURFACE-3KM LAPSE RATES NEAR 9C/KM WERE NOTED IN CENTRAL
NEBRASKA...WITH AROUND 8C/KM VALUES EAST AND ALSO SOUTHEAST INTO THE
LOCAL AREA.
THE MAIN ISSUES TONIGHT ARE WHERE AND HOW LONG THE SNOW SHOWERS WILL
LAST. THE VARIOUS GUIDANCE ALL POINTS TO A MORE SUSTAINED AREA OF
PRECIPITATION SOMEWHERE IN NORTHEAST KANSAS...WITH THE DETAILS THE
MAIN ISSUE. AS THE UPPER TROF CONTINUES SOUTH TO SOUTHEAST...THE
LAPSE RATES REMAIN NEAR 8C/KM WELL INTO THE NIGHT AS FRONTOGENESIS
AROUND 750MB INCREASES AND FOCUSES ON THE NORTHEAST TIP OF A
DEVELOPING THETA-E RIDGE AT THIS LEVEL...RESULTING IN GOOD LIFT
THROUGH THE DENDRITIC GROWTH ZONE. THE MOST RECENT HRRR AND RAP DATA
HAS BEEN PUSHING THIS AREA NORTHEAST...FAVORING FAR NORTHEAST KANSAS
MAINLY AROUND 03Z. HAVE INCREASED CHANCES AND AMOUNTS UP HERE...BUT
STILL LIMITED MOISTURE AND THE COVERAGE OF ANY BANDS AND EXACTLY
WHERE THIS WILL END UP KEEPS CHANCES BELOW LIKELY LEVELS. SOME BRIEF
MODERATE SNOWFALLS CAN BE EXPECTED IN THE HEAVIEST PRECIPITATION...
AND LOCAL AMOUNTS NEAR AN INCH SEEM PLAUSIBLE. ANY ACCUMULATING SNOW
SHOULD END WELL BEFORE SUNRISE AS THE UPPER TROF SWINGS INTO THE
MISSISSIPPI VALLEY. WESTERN AREAS SEE A QUICKLY DRYING TROPOSPHERE
THIS EVENING...BUT HIGH CLOUD RETURNS THERE LATE TONIGHT AS WARM AIR
ADVECTION ENSUES FROM THE UPPER PATTERN SHIFTING EAST. THOUGH
INSOLATION WILL BE LIMITED AS THE CLOUDS DEEPEN SATURDAY...SOUTHWEST
WINDS SHOULD SUPPORT TEMPS SEVERAL DEGREES ABOVE TODAYS LEVELS FOR
CENTRAL AND WESTERN LOCATIONS.
65
SHORTWAVE RIDGING AND WARM AIR ADVECTION IS EXPECTED TO BRING WARMER
TEMPS AND SUNNY SKIES TO THE AREA FOR SUNDAY. THEN THE NEXT
SHORTWAVE IS EXPECTED TO MOVE ACROSS THE CENTRAL AND NORTHERN PLAINS
BRINGING A COLD FRONT THROUGH THE AREA LATE SUNDAY NIGHT AND MONDAY
MORNING. MODELS CONTINUE TO SHOW THE BETTER MOISTURE TO THE EAST OF
THE FORECAST AREA. AND WITH THE FRONT PUSHING INTO MO BY THE LATE
MORNING HOURS...PRECIP CHANCES SHOULD BE CONFINED TO FAR EASTERN KS
DURING THE DAY MONDAY.
TUESDAY AND WEDNESDAY LOOK TO BE IN BETWEEN SYSTEMS WITH SURFACE
RIDGING BUILDING SOUTH THROUGH THE PLAINS. THIS SHOULD KEEP TEMPS
FROM WARMING UP VERY MUCH. THE NEXT BIG WEATHER MAKER LOOKS TO
IMPACT THE REGION WEDNESDAY NIGHT AND THURSDAY. BOTH THE GFS AND
ECMWF HAVE TRENDED SLIGHTLY SLOWER WITH THE UPPER CLOSED LOW AS IT
MOVES OUT OF THE SOUTHERN ROCKIES. HOWEVER THE GFS REMAINS SLIGHTLY
FASTER THAN THE GFS. THE OTHER TREND OF NOTE IS THE ECMWF FURTHER
NORTH WITH THE TRACK OF THE LOW PRESSURE SYSTEM. THIS COMPLICATES
THE FORECAST OF PRECIP TYPE QUITE A BIT. INITIALLY WITH THE COLD
SURFACE RIDGE IN PLACE WEDNESDAY...GFS FORECAST SOUNDINGS SUPPORT
ALL SNOW WEDNESDAY EVENING. HOWEVER BOTH MODELS SHOW STRONG WARM AIR
ADVECTION ALOFT AND A WARM NOSE DEVELOPING THROUGH THE NIGHT WITH
SURFACE TEMPS REMAINING IN THE 20S AND LOWER 30S. AS THE WARM AIR
ADVECTION DEVELOPS...FREEZING RAIN AND SLEET BECOME POSSIBLE WHILE
SURFACE TEMPS ARE BELOW FREEZING. ON TOP OF THIS IS THE POTENTIAL
FOR MID LEVEL DRY AIR TO WRAP UP IN THE SYSTEM AND FOR THE SOUNDINGS
TO LOOSE SATURATION WITHIN THE DENDRITIC GROWTH LAYER ADDING TO THE
POTENTIAL FOR FREEZING RAIN. REALLY THE TRACK OF THE SYSTEM DOES NOT
FAVOR AN ALL SNOW EVENT FOR THE BULK OF THE FORECAST AREA.
CONFIDENCE IN TRYING TO NAIL DOWN PRECIP TYPE IS VERY LOW AT THIS
POINT GIVEN THAT IT IS 6 DAYS OUT...BUT THINK THAT THE PROBABILITY
OF MIX WINTRY PRECIP IS HIGH ENOUGH THAT IT SHOULD BE MENTIONED IN
THE FORECAST. ONE SHOULD NOT GET CAUGHT UP ON WHERE THE FORECAST HAS
THE RAIN/SNOW LINE /WHICH IS LIKELY TO FLUCTUATE IN THE COMING
DAYS/...BUT THAT THERE IS THE POTENTIAL FOR A MIXED BAG OF PRECIP.
THINGS THAT COULD CHANGE THIS IS IF THE MAGNITUDE OF LOW LEVEL WARM
AIR ADVECTION WERE TO INCREASE AND RAISE SURFACE TEMPS ABOVE
FREEZING OR IF THE STORM SYSTEM TRENDS SOUTH AGAIN. IN ANY CASE IT
LOOKS TO BE MESSY.
WOLTERS
&&
.AVIATION...
KTOP AND KFOE WILL REMAIN UNDER VFR STRATUS AND AT TIMES MVFR
STRATUS WITH OCCASIONAL LIGHT SNOW OR FLURRIES THROUGH AT LEAST
12Z. KMHK SHOULD REMAIN WEST OF THE STRATUS DECK THIS MORNING. VFR
STRATUS MAY FORM AT THE TAF SITES BY AFTERNOON.
GARGAN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1127 PM CST Fri Feb 15 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Short Range (Tonight through Sunday)...
Main weather concern for this period centers on the overnight period
but confined to only the western third of the CWA. One last
vorticity max/shortwave diving down the backside of a retreating
broad upper trough will drop south-southeast across eastern NE
passing just west of the MO/KS state line overnight. Satellite
imagery and radar returns suggest two vorticity maxima...one moving
into northeast NE and a second west of BIE. Features are best seen
on NAM h7 prog. Scattered snow showers a bit more widespread than
shown by NAM output while RAP looks too generous on qpf. Prefer
blending the two model outputs which results in higher pops and
expanding snow shield a bit more east. Moderately high liquid/snow
ratios show potential for a narrow swath of 1+ inches of snow over
the far western counties. Given the expected scattered coverage of
the snow prefer keeping pops under the likely category for now. Snow
will have exited the southwestern CWA by Saturday morning with
clearing from north to south.
Saturday will bring the start of a welcome warmup over the Plains
which will quickly spread east...reaching into the western counties
by the afternoon hours. A band of dense mid level clouds will spread
from west to east Saturday night and herald the arrival of the
deepening warm air advection zone. Still expecting a significant
warmup on Sunday although there may be a tighter west to east
gradient due as boundary layer winds take on a south-southeast
direction which will limit the degree of warming further east.
MJ
Medium Range (Monday through Friday)...
Next week continues to look very active, with two systems moving
through the Plains on Monday night and again from Wednesday night
through early Friday. The primary focus will be the significant
system for Wednesday night through Thursday night, which has the
potential to be a fairly major winter storm if the current track
pans out.
On Monday, a deep longwave trough will dive through the Central
Plains, driving a surface cold front through the CWA during the
daylight hours. A broad area of scattered rain showers will be
possible along and ahead of the front, but amounts will be light as
moisture return into the Plains will be quite limited. A brief mix
with snow may be possible along our eastern border if any light
precipitation can linger behind the surface boundary, but no snow
accumulation is expected.
By Wednesday night, a deep upper low will begin to eject out of the
four corners region. As it moves eastward into the southern Plains,
strong southerly flow will draw Gulf moisture into the system, which
will combine with the existing Pacific moisture and enhance
precipitation coverage and intensity as the system begins to lift
northeast. All model solutions bring the elevated warm front into at
least the southeastern two thirds of the CWA by Thursday morning but
keep cold air lingering at the surface over almost the entirety of
the area, indicating a potential for freezing rain in those areas.
Since this is a deviation from previous forecasts, have started out
with a slight chance for freezing rain on top of the primary
rain/snow mix, but the probability for ice may need to be heightened
if future forecasts look similar. As cold air wraps in behind the
850mb low, precipitation should change to all snow from west to east
during the day on Thursday, becoming all snow and lifting out of the
area after 00z Friday. Very preliminary snowfall totals range from
more than 6 inches across the northern third of the forecast area
where precipitation type is likely to be snow during the majority of
the event, to 2-3 inches in west central and eastern parts of the
CWA, then tapering to less than 2 inches in the far southwest where
rain or freezing rain will be the predominant precipitation type
during the majority of the event.
With the consistency of model solutions, both temporally and between
different model configurations, the overall potential for a winter
storm is increasing. However, precipitation types and snowfall
amounts are still somewhat uncertain and will need to be further
refined, especially as this system heads onshore early next week.
Laflin
&&
.AVIATION...
For the 06Z TAFs...band of light snow is rapidly weakening and
pushing into west central MO, south of the KC terminals. May still
see some brief light snow and MVFR restrictions lingering at MCI/MKC
at the start of the TAF period but in general expect rapid
improvement at these terminals soon. Behind the snow there is a
lingering swath of MVFR stratocumulus over northeast KS that is
skirting the STJ/MCI/MKC corridor. This may clip these terminals over
the next few hours but otherwise expect no significant aviation
concerns for the next 24 hours.
Hawblitzel
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
203 AM CST SAT FEB 16 2013
.UPDATE...
.SHORT TERM...
THE GEMREG...NAM...RUC AND HRRR SHOW A DEVELOPING WARM FRONT
MOVING EAST THROUGH NRN NEB THIS MORNING AND WEAKENING DURING THE
AFTN. RADAR SUPPORTS THE DEVELOPMENT OF SCATTERED SNOW SHOWERS.
SKIES SHOULD CLEAR OUT BEHIND THE WARM FRONT THROUGHOUT THE
MORNING...AFTN AND EVENING HOURS. TEMPERATURES TODAY RANGE FROM
NEAR 40 NORTHEAST TO MID 50S SOUTHWEST. LOW THROUGHOUT THE FCST
AREA TONIGHT FALL TO AROUND 20.
.PREV DISCUSSION... /ISSUED 1134 PM CST FRI FEB 15 2013/
AVIATION...
SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING
INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND
EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE
LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT
THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN
EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE
INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE
TIME BEING.
IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE
LIKELY TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO
VISIBILITY.
WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320
AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST
SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP OF
THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED CHANGE OF
ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT THIS TIME...
IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE THRESHOLD ALTITUDE
OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN THE TERMINAL FORECAST
FOR LBF. THE TIME OF THE GREATEST RISK OF LOW LEVEL WIND SHEAR WILL
BE 12-15Z.
PREV DISCUSSION... /ISSUED 337 PM CST FRI FEB 15 2013/
SYNOPSIS...
ISSUED AT 335 PM CST FRI FEB 15 2013
AT 21Z...WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH MOVING
THROUGH THE DAKOTAS AND CENTRAL NEBRASKA EMBEDDED WITHIN A TROUGH
CENTERED NORTH TO SOUTH THROUGH THE MISSISSIPPI RIVER VALLEY.
UPSTREAM...A STRONG RIDGE WAS IN PLACE ACROSS THE WEST
COAST...WITH A SHORTWAVE TROUGH MOVING TOWARDS BRITISH COLUMBIA.
LOCALLY...CONVECTIVE SNOW SHOWERS WERE SEEN ACROSS MUCH OF
NEBRASKA AS STEEP LOW LEVEL LAPSE RATES AND MIXING WAS OBSERVED.
SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 335 PM CST FRI FEB 15 2013
SHOWER ACTIVITY WILL DIMINISH THIS EVENING WITH THE LOSS OF
DAYTIME HEATING. CLOUD COVER WILL ALSO DIMINISH FOR A TIME DURING
THE EVENING HOURS AS THE FORECAST AREA SITS IN AN AREA OF
SUBISIDENCE ON THE BACKSIDE OF THE SHORTWAVE TROUGH.
A WARM FRONT WILL MOVE EAST ACROSS NEBRASKA OVERNIGHT...SO
EXPECTING LOWS EARLY /AROUND 06Z/. WARM ADVECTION ALOFT...ALONG
WITH SOME DECENT CONVERGENT AND LIFT ALONG THE FRONT COULD BRING
MORE LIGHT SNOW BEGINNING AFTER 09Z. PUT SOME FLURRIES IN THE
FORECAST FOR LOCATIONS ACROSS NORTHERN NEBRASKA NEAR HIGHWAY 83.
GOING INTO SATURDAY MORNING...AS THE FRONT TRANSITIONS EAST...THE
SNOW CHANCES WILL ALSO MOVE EAST INTO NORTH CENTRAL NEBRASKA.
DON/T BELIEVE ANY AMOUNTS WILL BE MUCH...MAYBE A TENTH OF AN INCH
OR SO...BUT DID ADD SNOW CHANCES EAST OF HIGHWAY 83 AND NORTH OF
HIGHWAY 91. BEHIND THE FRONT...MUCH WARMER AIR WILL MOVE INTO THE
AREA. BY 00Z SUNDAY...850MB TEMPERATURES WILL RISE 10 DEGREES OR
BETTER...WITH VALUES AROUND 5C OVER THE FAR SOUTHWEST COUNTIES.
THIS WARMING WILL LEAD TO HIGHS IN THE 40S AND EVEN LOW 50S ACROSS
THE FORECAST AREA. SNOW COVER DOES REMAIN FROM LAST WEEK/S SNOW
STORM...SO WILL LIKELY SEE AN AREA WITH COOLER HIGHS FROM THE EAST
CENTRAL PANHANDLE UP THROUGH NORTH CENTRAL NEBRASKA. SOME OF THESE
PLACES MAY ONLY SEE HIGHS UP IN THE UPPER 30S TO AROUND 40.
LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 PM CST FRI FEB 15 2013
A WARM FRONT WILL MOVE TO THE EAST ACROSS THE FORECAST AREA WITH
WARM DRY PACIFIC AIR AS THE RIDGE OVER THE WESTERN CONUS PUSHES
EAST. STILL SOME SNOW COVER OVER THE SANDHILLS BUT SATURDAYS HIGHS
EXPECTED TO CUT IT BACK SIGNIFICANTLY. HIGH TEMPERATURES SUNDAY
AROUND 50 SOUTH AND MID 40S NORTH. 850MB TEMPERATURES AROUND 9C
SUNDAY. LOW PRESSURE WILL MOVE ALONG THE CANADIAN BORDER AND DRAW
A COLD FRONT THROUGH THE NORTHERN PLAINS SUNDAY NIGHT INTO MONDAY
WITH STRONG COLD AIR ADVECTION...GUSTY NORTHWEST WINDS AND
POSSIBLY SOME LIGHT SNOW. HAVE LEFT DRY FOR NOW WITH BUFR
SOUNDINGS SHOWING HIGH BASED PRECIP VIRGA WITH MUCH DRIER LOWER
LEVELS. COLD ARCTIC AIR WILL MOVE SOUTH INTO THE CENTRAL PLAINS
THROUGH THE MIDDLE OF THE WEEK WITH HIGHS IN THE 30S MONDAY
FALLING INTO THE TEENS AND 20S FOR HIGHS ON THURSDAY FRIDAY.
TRAJECTORY OF STORM SYSTEM MOVING OUT OF THE ROCKIES AND ONTO THE
PLAINS WEDNESDAY WILL HAVE ABUNDANT MOISTURE FROM A WIDE OPEN
GULF. TRAJECTORY FURTHER WEST THAN USUAL WITH MOISTURE ADVECTING
ACROSS THE SOUTHERN PLAINS THROUGH THE TEXAS PANHANDLE INTO
NORTHEAST COLORADO FROM WEDNESDAY. STRONG DEEP EASTERLY FLOW OVER
WESTERN NEBRASKA WEDNESDAY INTO THURSDAY. HAVE UPPED POPS INTO
LIKELY CATEGORIES ON THURSDAY. REMAINS TO BE SEEN HOW MUCH
CONVECTION WILL BE OVER THE CENTRAL AND SOUTHERN PLAINS WHICH MAY
ROB NEEDED MOISTURE. MODELS CONTINUE IN GOOD AGREEMENT WITH THIS
SYSTEM. COOL DOWN TOWARDS THE END OF THE WEEK AND THEN GRADUALLY
WARMING INTO THE WEEKEND BUT REMAINING WELL BELOW NORMAL FOR THE
SEASON. MORE ACTIVE PATTERN.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...JACOBS
AVIATION....CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
354 AM EST SAT FEB 16 2013
.SYNOPSIS...
A STRONG TROUGH ALOFT WILL PIVOT ACROSS THE SOUTHEASTERN US
TODAY...AND RESULT IN RAPID CYCLOGENESIS UP THE MIDDLE ATLANTIC
AND NORTHEAST COASTS TONIGHT AND SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 340 AM SATURDAY...
...PERIOD OF WINTRY WEATHER REMAINS POSSIBLE THIS EVENING INTO
TONIGHT ALONG AND EAST OF HIGHWAY 1...
WILL LEAVE THE CURRENT ADVISORY AS-IS. EXPECT ACCUMULATIONS 1-2" AT
MOST...AND THOSE AMOUNTS ARE MOST LIKELY IN THE NE COASTAL PLAIN
NEAR THE VA BORDER N/NE OF THE TRIANGLE. ALTHOUGH IT APPEARS THAT
THE SURFACE CYCLONE WILL BE DEVELOPING CLOSER TO THE COAST (NEAR
MHX) THAN PREVIOUSLY ANTICIPATED AND THAT RELATIVELY MORE PRECIP
WILL OCCUR ACROSS CENTRAL NC (PER LATEST RAP MODEL RUNS) IN ASSOC/W
STRONG LOW-LEVEL FRONTOGENESIS 12-18Z AND THEN STRONG DPVA IN THE
PRESENCE OF A DESTABILIZING AIRMASS 21-00Z...IT APPEARS THAT THE
BOUNDARY LAYER WILL REMAIN TOO WARM THROUGH ~00Z THIS EVENING FOR A
CHANGEOVER TO OCCUR IN MOST LOCATIONS...WITH THE COLDER AIRMASS
CURRENTLY BUILDING INTO THE MID-ATLANTIC STALLING NORTH OF CENTRAL
NC DUE TO VERY STRONG H5 HEIGHT FALLS IN ADVANCE OF THE APPROACHING
UPPER LEVEL TROUGH...RESULTING IN BROAD PRESSURE FALLS OVER NC/VA
WHICH WILL HOLD A WEAK PRESSURE TROUGH IN PLACE AND DELAY THE
ARRIVAL OF THE COLDER AIRMASS FROM THE NORTH. EXPECT THE BEST
CHANGEOVER POTENTIAL TO OCCUR AFTER 00Z...WHEN FORCING FOR PRECIP
WILL GENERALLY BEGIN TO WANE OVER CENTRAL NC AND PRECIPITATION WILL
BEGIN TO PROGRESS EAST TOWARD THE COAST.
BASICALLY...THIS MAY BE YET ANOTHER CASE WHERE THE COLD AIR `CHASES`
THE PRECIP...EXCEPT PERHAPS N/NE OF THE TRIANGLE WHERE FAVORABLE
THERMAL PROFILES ARE MORE LIKELY TO COINCIDE WITH STRONG FORCING IN
THE FORM OF LOW-LEVEL FRONTOGENESIS AND STRONG DPVA IN THE PRESENCE
OF VERY STEEP (7-8C/KM) MID-LEVEL LAPSE RATES. ONE CAVEAT...GIVEN
STRONG DPVA...GOOD LOW-LEVEL FRONTOGENESIS AND VERY STEEP MID-LEVEL
LAPSE RATES (7-8 C/KM) IN ADVANCE OF THE APPROACHING UPPER LEVEL
TROUGH...IT IS POSSIBLE THAT A QUICK BURST OF ACCUMULATING
CONVECTIVE SNOW COULD OCCUR AT ABOUT THE SAME TIME AS THE COLDER
AIRMASS BEGINS TO ARRIVE FROM THE NORTH ~00Z FROM GUILFORD/RANDOLPH
COUNTIES EASTWARD. HOWEVER...PREVIOUS EXPERIENCE WOULD SUGGEST THAT
TOO MUCH UNCERTAINTY IS PRESENT TO WARRANT EXPANDING THE ADVISORY
AREA WHEN WAITING FOR A COLDER AIRMASS TO ADVECT INTO THE AREA AND
WHEN RELYING PRIMARILY ON CONVECTIVE PRECIPITATION FOR
ACCUMULATIONS. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 210 AM SATURDAY...
BREEZY COLD CONDITIONS EARLY SUNDAY WILL PERSIST MUCH OF THE DAY.
LOW LEVEL THICKNESSES SUGGEST THE COLDEST AIR WILL BE OVER THE
NORTHERN AND EASTERN ZONES WHERE HIGHS WILL STRUGGLE TO REACH NEAR
40. TEMPERATURES IN THE 40S EXPECTED ACROSS THE SOUTHERN TIER NEAR
THE SC BORDER. THE COLD UPPER TROUGH IS FORECAST TO BEGIN TO LIFT
OUT LATE SUNDAY INTO MONDAY. HOWEVER... THE COLD SURFACE HIGH
PRESSURE IS FORECAST TO BE DIRECTLY OVERHEAD SUNDAY NIGHT INTO 12Z
MONDAY. THIS WILL MEAN COLD/CLEAR/CALM CONDITIONS WITH HEAVY FROST
AND HARD FREEZE BY 12Z MONDAY. LOWS 18-25. WAA WILL BEGIN MONDAY...
ESPECIALLY IN THE AFTERNOON. OTHER THAN A FEW HIGH CLOUDS... IT
SHOULD BE MOSTLY SUNNY WITH SW WINDS 10-15 MPH. HIGHS 48 TO 55 NE TO
SW.
&&
.LONG TERM / MONDAY NIGHT THROUGH FRIDAY/...
AS OF 210 AM SATURDAY...
A COUPLE OF SYSTEMS ARE EXPECTED TO BRING RAIN CHANCES TO OUR REGION
THIS WEEK. THE FIRST IS FORECAST FOR TUESDAY. STRONG WARMING OUT
AHEAD OF THE COLD FRONT WILL LEAD TO ALL RAIN SHOWERS. A BIT OF
IN-SITU CAD MAY KEEP TEMPS DOWN IN THE PIEDMONT. QPF CONTINUES TO BE
LIGHT WITH UP TO 0.25 IN THE NW WITH LESSER AMOUNTS TO THE EAST.
CLOUDY WITH A 40-50 PERCENT CHANCE OF SHOWERS. HIGHS GENERALLY IN
THE 45-50 RANGE NW... WITH 50S SE AFTER LOWS OF 35-42 TUESDAY.
WEDNESDAY AND THURSDAY... HIGH PRESSURE SHOULD BUILD IN FROM THE NW
AND NORTH WED-THU... WITH THE STRONGEST CAA EXPECTED THU. THIS MAY
SET UP A STRONGER CAD EVENT FOR FRIDAY AS THE HIGH IS FORECAST TO BE
IN A FAVORABLE POSITION AND STRENGTH TO INDUCE CAD AS THE NEXT
SYSTEM APPROACHES FRIDAY.
WED...FAIR AND SEASONABLE. LOWS IN THE 30S. HIGHS IN THE 50S. THU...
MOSTLY SUNNY. LOWS 25-30. HIGHS 48-53. FRI..MOSTLY CLOUDY. A CHANCE
OF RAIN. CHILLY. LOWS IN THE 30S. HIGHS IN THE 40S EXCEPT 50-55 SE.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 100 AM SATURDAY...
AFTER INITIALLY VFR CONDITIONS...THE PASSAGE OF A STRONG DEEP LAYER
FRONTAL ZONE WILL RESULT IN A RAPIDLY EXPANDING...BUT NARROW...
PRECIPITATION AXIS ACROSS THE WEST-CENTRAL CAROLINAS BETWEEN 09-15Z.
THE PRECIPITATION AXIS WILL THEN EXPAND IN AREAL EXTENT AND PIVOT
EASTWARD ACROSS CENTRAL NC THROUGH THIS EVENING...OWING TO THE
AMPLIFICATION OF A STRONG TROUGH ALOFT FROM THE CENTRAL PLAINS TO
THE SOUTHEAST STATES. THE PRECIPITATION WILL LIKELY BEGIN AS A MIX
OF RAIN AND SNOW...BEFORE GRADUALLY TRANSITIONING TO ALL SNOW FOR
THE AFTERNOON AND EVENING HOURS. CEILINGS AND VISIBILITY
RESTRICTIONS WILL CONSEQUENTLY FALL INTO MVFR-IFR RANGE...BEFORE THE
STEADY PRECIPITATION ENDS AND SKIES CLEAR FROM WEST TO EAST THIS
EVENING. A FEW LINGERING SNOW SHOWERS WILL BE POSSIBLE THROUGH
MIDNIGHT...HOWEVER...AS THE VERY COLD AND DYNAMIC TROUGH AXIS ALOFT
PIVOTS EASTWARD.
LOOKING AHEAD: BREEZY CONDITIONS SUNDAY...FOLLOWED BY ANOTHER
FRONTAL SYSTEM AND ASSOCIATED SUB-VFR CONDITIONS AND RAIN THAT WILL
AFFECT THE REGION TUE.
&&
RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 PM SATURDAY TO 4 AM EST SUNDAY FOR
NCZ007>011-025>028-041>043-077-078-085-086-088-089.
&&
$$
SYNOPSIS...MWS
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...MWS
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
414 AM EST SAT FEB 16 2013
.SYNOPSIS...
A MOIST UPPER LEVEL LOW WILL CROSS THE REGION TODAY...WITH DRY HIGH
PRESSURE BUILDING IN FROM THE NORTH SUNDAY. A COLD FRONT WILL
APPROACH THE CAROLINAS AND NORTHEAST GEORGIA TUESDAY WITH ANOTHER
AREA OF CANADIAN HIGH PRESSURE BUILDING IN ON WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF EARLY SAT MORNING...UPPER TROUGH WILL SWING THROUGH THE REGION
TODAY WITH FURTHER COLD ADVECTION AND STRONG VORT MAX ACCOMPANYING
IT. VERY LIGHT PRECIP ALREADY FALLING OVER THE PIEDMONT. THIS AREA
IS FAVORED BY THE NAM...GFS...RAP AND HRRR AS BEING THE FOCUS FOR
THE BULK OF THE PRECIP. FORCING FROM THE WAVE WILL BE ENHANCED OVER
THE PIEDMONT BY LOW LEVEL CONVERGENCE BETWEEN THE INVADING ARCTIC
AIRMASS AND EXISTING COASTAL AIR. THE TROUGH STEADILY PROGRESSES
EAST...WITH THE BASE HAVING DEPARTED THE CWFA BY 00Z...WITH DEEP DRY
AIR RAPIDLY WORKING IN.
TEMPERATURE PROFILES DO NOT INDICATE A WARM NOSE GIVEN THE ALREADY
COLD AIR IN PLACE. DEEP SATURATION MEANS RAIN OR SNOW WILL MAINLY BE
DETERMINED BY SURFACE TEMP. FREEZING LEVELS ARE PRETTY LOW AND SFC
TEMPS WILL BE MOSTLY IN THE 30S OVER THE PIEDMONT. A RAIN/SNOW MIX
WILL LIKELY TRANSITION TO SNOW AS THE FREEZING LEVEL LOWERS DUE TO
THE WET BULB EFFECT. FOR QPF...SOMEWHAT TRICKY WITH OPERATIONAL
MODELS SHOWING SOME POSSIBLE CONVECTIVE EFFECTS AND LOCALIZED AREAS
SEEING SIGNIFICANTLY HIGHER AMOUNTS OF SNOWFALL. INDEED BOTH THE NAM
AND GFS SHOW UP TO A COUPLE HUNDRED JOULES OF MUCAPE THIS AFTERNOON
OVER A PORTION OF NE GA AND THE WESTERN UPSTATE. 21Z SREF BACKS THIS
UP WITH LIKELY-RANGE PROBS OF 100 J. SO THIS COULD HELP ENHANCE
TOTALS DURING THE EARLY TO MID AFTERNOON WHEN THE FORCING IS
STRONGEST ANYWAY. CHOSE MODEST QPF DERIVED FROM A MODEL BLEND WHICH
HAPPENS TO BE IN LINE WITH THE GENERAL PATTERN AND AMOUNTS OF THE
LAST FEW GFS RUNS...WITH ABOUT A QUARTER INCH SOUTHEAST OF A LINE
FROM GREENWOOD TO CHESTER. FAIRLY HIGH SNOW RATIOS OF 13-16 TO 1
WILL PRODUCE TOTALS GENERALLY OF 1 TO 2 INCHES TODAY. THIS MEETS OUR
WINTER WX ADVY CRITERIA OVER THE SRN FOOTHILLS AND PIEDMONT OF NC AS
WELL AS MOST OF THE SC PIEDMONT.
IN ADDITION TO THE SYNOPTIC FORCING...PERSISTENT NORTHWEST FLOW WILL
PRODUCE ENHANCED SNOWFALL IN THE UPSLOPE AREAS OF THE MOUNTAINS.
NONETHELESS...TOTALS ARE COMPARABLE TO PREVIOUS FCST AND EXISTING
WINTER WX ADVY WILL COVER THIS.
HIGH TEMPS TODAY WILL BE WELL BELOW NORMAL IN THE ARCTIC AIR. WITH
MOSTLY OVERCAST SKIES USED A BLEND OF GFS AND CMC-REGIONAL TEMPS.
BOTH THE GFS AND NAM QUICKLY DRY THINGS OUT BEHIND THE DEPARTING
TROUGH SO SOME BREAKS IN THE CLOUD COVER COULD COME LATE IN THE DAY
ESPECIALLY SOUTHWEST...BUT PROBABLY TOO LATE TO HAVE MUCH OF AN
IMPACT ON HIGHS. FURTHERMORE ANY SNOW COVER COULD LIMIT TEMPS FROM
RISING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
AS OF 300 AM SATURDAY...THE UPPER TROUGH AXIS WILL PROGRESS QUICKLY
ACROSS THE REGION TONIGHT...BRINGING A QUICK END TO ANY LINGERING
PRECIP. THE ONLY EXCEPTION WILL BE ACROSS THE FAR WESTERN NC MTNS...
AS A MOIST NW FLOW SHOULD YIELD PERSISTENT SNOW SHOWERS THROUGH THE
OVERNIGHT. THE MODELS ARE RATHER STINGY WITH QPF TONIGHT...AS THE
NAM BARELY SQUEEZES OUT .05-.1 INCH ALONG THE TENN BORDER...WHILE
THE GFS IS EVEN DRIER. THIS IS SOMEWHAT SURPRISING...AS THE MOIST
LAYER IS PROGGED TO EXTEND TO ABOUT 800 MB THROUGH THE OVERNIGHT...
WHILE H8 WINDS SHOULD BE IN THE 30-40 KT RANGE. IN ADDITION...TEMPS
IN THE MOIST LAYER ARE EXPECTED TO BE EXTREMELY COOL...AS LOW AS -19
C BY 12Z SUNDAY. THEREFORE...EVEN IF THERE IS LITTLE LIQUID
EQUIVALENT...THIS PATTERN IS SUGGESTIVE OF EFFICIENT SNOW
PRODUCTION...WITH SNOW:LIQUID RATIOS AS HIGH AS 30:1 POSSIBLE LATE
TONIGHT. THEREFORE...WE WILL FORECAST AN ADDITIONAL 1 TO 4 INCHES IN
THE USUAL NW FLOW AREAS OVERNIGHT.
TEMPS WILL BE VERY COOL TONIGHT THROUGH TOMORROW...EASILY 10 DEGREES
BELOW CLIMO. HOWEVER...WITH HEIGHTS RISING IN THE WAKE OF THE UPPER
TROUGH AXIS...THE REMAINDER OF THE SHORT TERM WILL FEATURE QUICKLY
MODERATING TEMPS THAT WILL WARM VERY CLOSE TO NORMAL BY MONDAY
AFTERNOON.
BY THE END OF THE PERIOD...A MAJOR STORM SYSTEM WILL LIFT OUT OF THE
CENTRAL PLAINS...WITH AN ATTENDANT FRONTAL BAND OF PRECIP EXPECTED
TO MARCH ACROSS THE TENN VALLEY LATE MONDAY/MONDAY NIGHT. POPS WILL
INCREASE QUICKLY FROM WEST TO EAST ACROSS OUR AREA LATE MONDAY
NIGHT...BECOMING LIKELY ACROSS THE NC MTNS BY DAYBREAK. IT STILL
APPEARS THAT PRECIP COULD BEGIN AS SNOW IN THE HIGH ELEVATIONS OF
THE NC MTNS. THERE COULD ALSO BE SOME BRIEF FREEZING RAIN IN
SHELTERED VALLEYS TUE MORNING...BUT THE PREDOMINANT P-TYPE SHOULD BE
RAIN IN ALL AREAS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 AM SATURDAY...THE COLD FRONT WILL STILL BE OFF TO THE WEST
BY 12Z TUE WITH A DECENT SPREAD OF LIGHT PRECIP ACROSS MOST OF THE
CWFA...INCREASING EAST THROUGHOUT THE DAY. THE STRONGEST QG FORCING
WILL REMAIN NORTH DURING FROPA...HOWEVER A 100 KT FINGER OF THE STJ
WILL PUSH INTO MIDLANDS AND PROVIDE SOME MEASURE OF UPPER DIV
SUPPORT OVER THE SRN MOST ZONES. THE FLOW BACKS DOWN THE PROFILE AND
THE LLVL JET BECOMES ALIGNED PARALLEL TO THE BLUE RIDGE...THUS
MECHANICAL LIFT WILL BE LIMITED. ALL THIS TO SAY THE ADDITIONAL
PRECIP AMOUNTS UNTIL FROPA EARLY WED WILL BE RATHER LIGHT WITH MOST
AREAS RECEIVING LESS THAN A QUARTER INCH. THERE COULD BE SOME WRAP
AROUND -SNSH LINGERING ACROSS THE NRN MTNS THROUGH 06Z WED...BUT THE
TREND HAS BEEN FOR LESS AND LESS AVAILABLE MOISTURE...ESP WITH THE
ECMWF. IN ANY CASE...ANY AMOUNTS OF SNOW WILL BE LIGHT BTW 00Z-06Z
WED. HIGH TEMPS WILL BE TRICKY WITH ALL THE CLOUDS/PRECIP...YET
DECENT SW/LY FLOW...BUT MAXES A CAT OR SO BELOW NORMAL SEEMS
REASONABLE PER THE LLVL THICKNESS PATTERN AND SUFFICIENT LACK OF
INSOL.
THE MODELS AGREE WELL WITH THE PATTERN WED THROUGH THE END OF THE
PERIOD. A SHARP RIDGE AXIS WILL BUILD ACROSS THE PLAINS STATES AND
PROPAGATE TOWARD THE EAST COAST THROUGH 00Z FRI. THIS WILL MAINTAIN
CANADIAN HIGH PRESSURE AT THE SFC AND LOW BL THETA/E AIR WED AND
THU. GOOD INSOL...BUT N/LY FLOW WILL KEEP MAXES NEAR NORMAL
PERHAPS A DEGREE OR SO BELOW WED. A MODIFYING AIRMASS WITH
INCREASING MID/HIGH CLOUDS THU SHOULD HOLD MAX TEMPS IN CHECK AT
ABOUT 3-4 DEGREES BELOW NORMAL.
ANOTHER LOW PRESSURE SYSTEM DEEPENS AND MOVES INTO THE CENTRAL
MIDWEST BY THU EVENING. THE BEST UPPER DYNAMICS AGAIN WILL BE WELL
NORTH OF THE CWFA BY THE TIME A COLD FRONT REACHES THE NC MTNS
AROUND MID DAY FRI. THE MAIN PRECIP TYPE LOOKS TO BE ALL RAIN...WITH
SOME HIGH ELEV SNOW. AGAIN...AMOUNTS LOOK TO REMAIN ON THE LOW SIDE.
THERE COULD BE A DEVELOPING TRIPLE POINT LOW AND A MEASURE OF
SFC/BASED SHEAR STORM DEVELOPMENT FRI AFTERNOON...BUT INSTABILITY BE
A LIMITING FACTOR FOR ANY REAL STRONG/SVR CONCERN OR CONJECTURE AT
THIS POINT. THE CWFA WILL LIKELY SEE A NOTICEABLE GRADIENT OF MAX
TEMPS FRI AS THE LLVL THERMAL TROF EXITS TO THE NORTH AND A WARM
FRONT IMPINGES UPON THE AREA FROM THE SOUTH. FOR NOW...GENERALLY
THINK MAX TEMPS WILL BE A 3-5 DEGREES ABOVE NORMAL SOUTH AND ABOUT
5-8 DEGREES BELOW NORMAL NORTH OF I40.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR CIG WITH UNLIMITED VSBY EXPECTED TO PERSIST FOR MUCH
OF THE NIGHT. NAM AND GFS GUIDANCE BOTH INDICATIVE OF PRECIP
DEVELOPING OVER THE NC PIEDMONT JUST BEFORE DAYBREAK IN AREA OF LLVL
CONVERGENCE ASSOCIATED WITH FURTHER PUSH OF COLD AIR. GFS AND ITS
DERIVATIVES BRING THIS IN WITHOUT RESTRICTIONS WHILE THE NAM FAMILY
SHOWS LOW MVFR TO IFR CIGS. CAN/T TOTALLY DISREGARD THIS THOUGH THE
FORCING IS NOT IDEAL AND BOTH MODELS ARE OVERDOING PRECIP ATTM.
LOWERING CIG LIKELY THROUGH THE MORNING SO TO HANDLE THE POTENTIAL
JUST MOVED THE MVFR UP TO 11Z. 00Z MODEL PACKAGE STILL SUPPORTIVE OF
A MIDDAY PEAK IN PRECIP ACTIVITY AHEAD OF UPPER TROUGH PASSAGE. SFC
TEMPS MAY BE ABOVE FREEZING THOUGH SNOW WOULD STILL BE ABLE TO REACH
THE SFC...IF NOT SNOW THEN RAIN. CIGS LIFT TO VFR BY AFTERNOON THEN
SCATTER AFTER 00Z SUN. NW WINDS THRU THE PERIOD. BIGGEST GUST
POTENTIAL IS IN THE EVENING WITH INCREASING COLD AIR ADVECTION
PROMOTING MIXING.
ELSEWHERE...MOSTLY VFR CIGS TONIGHT WITH NO VSBY RESTRICTIONS
ANTICIPATED. GUIDANCE INDICATES SOME POSSIBILITY OF MVFR CIG
DEVELOPING WITH PRECIP JUST BEFORE DAYBREAK OVER THE ERN PIEDMONT
THOUGH CONFIDENCE IS LOW THAT THAT WOULD HAPPEN. CIGS HOWEVER LIKELY
TO LOWER WITH INCREASING DEEP MOISTURE BY THE EARLY DAYTIME HOURS.
MVFR CIGS WILL ACCOMPANY PRECIP IN THE LATE MORNING WEST TO MIDDAY
EAST. PRECIP TYPE WILL SOMEWHAT DEPEND ON SFC TEMP THOUGH SNOW
SHOULD BE ABLE TO AT LEAST MIX IN AT ALL THE SITES. CHC TOO LOW TO
MENTION AT KAND BUT IS INCLUDED ELSEWHERE. RETURN TO VFR BY LATE
AFTN WITH GUSTS POSSIBLE FROM MIDDAY THROUGH THE END OF THE PERIOD
AS COLD ADVECTION MAINTAINS DEEPLY MIXED SFC LAYER.
OUTLOOK...MOISTURE AND SOME RESTRICTIONS WILL REMAIN ALONG THE TN
BORDER THROUGH EARLY SUNDAY. ELSEWHERE...CONDITIONS WILL GENERALLY
REMAIN DRY WITH VFR CONDITIONS. HIGH PRESSURE BUILDS OVER THE REGION
EARLY NEXT WEEK.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-09Z
KCLT HIGH 94% MED 75% HIGH 95% HIGH 100%
KGSP HIGH 91% LOW 55% HIGH 100% HIGH 100%
KAVL HIGH 98% MED 77% HIGH 100% HIGH 100%
KHKY HIGH 97% MED 76% HIGH 100% HIGH 100%
KGMU HIGH 94% LOW 54% HIGH 100% HIGH 100%
KAND HIGH 91% LOW 53% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.FIRE WEATHER...
DRY AND BREEZY TO WINDY CONDITIONS ARE EXPECTED ON SUNDAY.
HOWEVER...THE LOWEST RH VALUES WILL BE MID TO LATE AFTERNOON...WHILE
THE WINDIEST CONDITIONS SHOULD BE IN THE MORNING THROUGH EARLY
AFTERNOON. IN ADDITION...WE WILL HAVE TO WAIT AND SEE HOW MUCH
PRECIPITATION FALLS OVER THE NEXT 24 TO 36 HOURS IN ORDER TO ASSESS
FUEL MOISTURE CONTENT AND ASSOCIATED FIRE DANGER FOR LATE THIS
WEEKEND.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ033-
048>052-058.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NCZ053-
065-068>072-082-501-503-505-507>510.
SC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR SCZ002-
003-005>009-012>014.
&&
$$
SYNOPSIS...SBK
NEAR TERM...WIMBERLEY
SHORT TERM...JDL
LONG TERM...SBK
AVIATION...WIMBERLEY
FIRE WEATHER...GSP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1139 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT MOVES EAST OF THE REGION OVERNIGHT...FOLLOWED BY A
STRONGER ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF
LOW PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE
CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE
ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE
APPALACHIANS LATE MONDAY NIGHT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 950 PM EST FRIDAY...
BASED ON ADDED SNOWFALL REPORTS OF AROUND 3 INCHES IN TAZEWELL CTY
ALONG WITH DEVELOPING SLICK ROAD CONDITIONS...WENT AHEAD WITH A
WINTER WEATHER ADVISORY THROUGH 4 AM FOR TAZEWELL...MERCER AND
BLAND CTYS WHERE COULD SEE UP TO 4 INCHES OF SNOW BEFORE THINGS
TAPER OFF TO FLURRIES.
AS OF 845 PM EST FRIDAY...
PERSISTENT BAND OF SNOW REMAINS ACROSS FAR SW VA INTO SE WVA ALONG
THE LEADING EDGE OF THE DEEPENING 5H TROF TO THE WEST AND UNDER A
WEAK SHORTWAVE AHEAD OF THE MAIN UPPER COLD POOL. WARM SURFACES
FROM EARLIER TODAY HAVE APPARENTLY LIMITED ACCUMULATIONS DESPITE
SEVERAL HOURS OF DECENT SNOWFALL WITH TOTALS OF 1-2 INCHES REPORTED
MAINLY ON GRASSY SURFACES. SINCE APPEARS WILL BE TAPERING SHORTLY
WONT HOIST AN ADVISORY YET UNLESS HEAVIER BANDS PERSIST LONGER.
OTRW LATEST RAP AND LOCAL RNK WRF SHOW THIS BAND OF SNOW FINALLY
WEAKENING BEFORE MIDNIGHT AS ENERGY SHIFTS EAST AND THE 85H FLOW
TURNS MORE NNW. THUS KEEPING IN A FEW MORE HOURS OF CAT/LIKELY
POPS THERE BEFORE DIMINISHING AFTER MIDNIGHT. OTRW COLD FRONT NOW
ENTERING THE PIEDMONT WITH A FEW RAIN SHOWER BANDS ALONG IT OVER
THE SE IN STRONG SW FLOW ALOFT DEPICTED OFF EVENING SOUNDINGS.
EXPECT THIS RAINFALL TO AFFECT AREAS MAINLY EAST OF THE BLUE RIDGE
BEFORE THE FRONT FINALLY GETS FAR ENOUGH EAST OF THE REGION TO
SUPPORT A LITTLE BETTER DOWNSLOPING IN THE NEXT FEW HOURS. THUS
THINKING WILL SEE A LULL IN PRECIP FOR THE MOST PART DURING THE
EARLY MORNING HOURS WITH THE FRONT TO THE SE...ONLY WEAK UPSLOPE
OVER THE WEST...AND LITTLE SUPPORT ALOFT AS WE SLIDE IN BETWEEN
UPPER IMPULSES LATER TONIGHT. THIS IN LINE WITH POPS FROM EARLIER
FOR AFTER MIDNIGHT SO ONLY TWEAKED POP COVERAGE LATER ON. HAVE
SEEN LITTLE SNOW IN THE ADVISORY AREA BUT LEAVING HEADLINES AS IS
FOR NOW. TEMPS SLOW TO FALL OUT EAST BUT WILL GET INTO BETTER COLD
ADVECTION SHORTLY WITH THE LAV MOS LOOKING TOO WARM MOST SPOTS
OVERNIGHT.
PREVIOUS DISCUSSION...
A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS
AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS
UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS
FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP
WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST
AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR
A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP
MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD
LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR
AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE
GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND
A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE
HEAVIEST AMOUNTS OUT OF FORECAST AREA.
STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS
FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS
TO THE EAST AND NO HEADLINES.
AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND
UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST
VIRGINIA.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 408 PM EST FRIDAY...
LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE
MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD
JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT.
DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD
ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST.
ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN
SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME
SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL
DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE
DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE
WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND
6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN
INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET.
WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC
WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS
CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND
GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY
NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A
SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE
DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING
AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER
TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE
GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE
MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF
SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 350 PM EST FRIDAY...
HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT
TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY
STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY
HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL
PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH
HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING
CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING
CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES
ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE
COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE
SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND
PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE
JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE
SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL
CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO
FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER
RIDGES ALONG THE BLUE RIDGE.
HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH
BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED
TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT
PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z
GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION
FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A
PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING
DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT
FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST
SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE
THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO
BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER
AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE
OHIO VALLEY PER THE ECMWF.
TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH
PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY
AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH
A WET COLD AIR DAMMING EVENT EXPECTED.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1130 PM EST FRIDAY...
COLD FRONT NOW CROSSING INTO THE PIEDMONT WITH A LINGERING BAND OF
MOSTLY RAIN SHOWERS ALONG AND BEHIND THE BOUNDARY MAINLY FROM KLYH
TO KMTV ATTM. LOCAL WRF CONTINUES TO STILL HAVE THE BEST HANDLE
SO WILL FOLLOW CLOSELY AND PUSH RAIN A BIT FARTHER EAST INTO
KLYH/KDAN FOR A FEW HOURS OVERNIGHT SINCE GOOD DOWNSLOPE IS
LAGGING THE FRONT. OTRW WILL HAVE PERIODIC MVFR TO IFR AT
KBLF WHERE SNOW HAS FINALLY TAPERED OFF...AND MOSTLY MVFR AT
KLWB/KBCB AS EXPECTING UPSLOPE TO KEEP LOW CIGS ALONG THE WESTERN
SLOPES WITH SOME OF THE COLD ADVECTION STRATO-CU SPILLING EAST
TOWARD THE BLUE RIDGE OVERNIGHT. MAY CONTINUE TO INCLUDE A VFR
MENTION OF A -SHSN OVERNIGHT IN THE WEST BUT LOOKING QUITE
ISOLATED UNTIL LATE AT BEST WHEN BETTER UPSLOPE KICKS IN. ELSW
WILL MAINTAIN VFR OUT EAST PENDING JUST HOW FAR THE PRECIP GETS IN
THE NEXT FEW HOURS BUT EVEN THEN APPEARS CIGS AOA 4K FT. KLWB AND
KBLF WILL TRANSITION TO AN UPSLOPING PCPN -SHSN EVENT BY DAYBREAK
AND CONTINUE OFF AND ON THROUGH SATURDAY. STILL LOOKING FOR MVFR
CIGS/VSBYS AND EXPECT -SHSN TO BE LIGHT AS BEST MOISTURE WILL BE
TO THE EAST WITH THE OFFSHORE LOW TAKING SHAPE.
KDAN/KLYH IS INTERESTING FOR THE LATTER PORTION OF THE TAF
PERIOD. LIFT DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW
SLIDING OFF THE COAST WILL BEGIN TO DEVELOP A PRECIPITATION
SHIELD TO THE WEST. IT CURRENTLY LOOKS LIKE KDAN WILL BE ON THE
EDGE OF THIS AND WILL INTRO A PERIOD OF MVFR CIGS IN AFTER 12Z
ALONG WITH SOME PCPN THAT MAY BE ALL SNOW DURING THE MORNING. ALSO
POTENTIAL FOR A NARROW RIBBON OF SNOW OR SNOW SHOWERS TO DEVELOP
NEAR HIGHWAY 29 SATURDAY AFTERNOON WHICH COULD BRING LOCALIZED
MVFR/IFR IN A SWATH SO INCLUDING A BIT MORE SNOW MENTION AT BOTH
KDAN/KLYH AGAIN SATURDAY AFTERNOON BUT LOW CONFIDENCE AT THIS
POINT.
LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN
RESPONSE TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT
WINDS TO HAMPER AVIATION INTERESTS UNTIL LATE SATURDAY OR MORESO
SATURDAY NIGHT.
EXTENDED AVIATION DISCUSSION...
REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS
DISCUSSION:
HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY
SUNDAY ALTHOUGH NW WINDS WILL BE QUITE STRONG AND GUSTY. GOOD
FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A NEW COLD
FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH MVFR/IFR
CEILINGS. VFR QUICKLY RETURNS ON WEDNESDAY WITH HIGH PRESSURE
FOLLOWING THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR VAZ007-010.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018.
WV...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR WVZ042.
&&
$$
SYNOPSIS...AMS/KM
NEAR TERM...AMS/JH/PH
SHORT TERM...KM
LONG TERM...RCS
AVIATION...AMS/JH/NF
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1048 PM CST FRI FEB 15 2013
.SHORT TERM...THROUGH MONDAY NIGHT
319 PM CST FRI FEB 15 2013
BENIGN WEATHER THROUGH THE WEEKEND LEADS INTO MONDAYS WEATHER
SYSTEM WHICH WILL NEED TO BE WATCHED FOR CHANGES.
MUCH LESS CLOUD ACROSS THE AREA TODAY THAN FORECAST WITH MIXING
NOT DEEP ENOUGH TO FORM MUCH STRATOCUMULUS EXCEPT OVER
NORTH-CENTRAL WI. LONGWAVE TROUGH AXIS CONTINUES EASTWARD PROGRESS
WITH LAST OF SHORTWAVE TROUGH ENERGY COMING THROUGH TONIGHT AND
EARLY SATURDAY. LATEST RAP AND WATER VAPOR HAS THIS BROAD
CIRCULATION AXIS FROM KINL-KLBF...AND SURFACE LOW PRESSURE IN
EASTERN NEB. CLOUD COVER OVER NWRN MN MOVING TOWARD THE AREA WILL
ARRIVE THIS EVENING FOR A CLOUD PERIOD INTO SATURDAY MORNING. NOT
TO CONFIDENT ON THE COVERAGE OF THIS CLOUD COMING IN...IT MAY BE
MORE IN AREAS. HAVE LEFT A MENTION OF FLURRIES IN THIS WEAKLY
LIFTED AIR MASS THROUGH NOON SATURDAY.
AGGRESSIVE RIDGE BUILDING THEN TAKES PLACE LATER SATURDAY AND
SUNDAY. UPSTREAM RAOB HEIGHT RISES SEEN ACROSS WRN CANADA WITH
THIS PROGRESSIVE HIGHER AMPLITUDE RIDGE. HAVE COOLED THE LOW
TEMPERATURES SUNDAY MORNING OVER CENTRAL WI WITH NEARLY CALM WINDS
AND LITTLE CLOUD UNDER LOW-LEVEL RIDGING. THESE ARE BELOW MOS
GUIDANCE BY ABOUT 5-7F. WARM ADVECTION WILL BEGIN TO RAISE
TEMPERATURES SUNDAY AND THE FORCING DOES NOT SEEM SUFFICIENT TO
CREATE PRECIPITATION PER CONSENSUS 15.12Z MODEL GUIDANCE.
HOWEVER...THE WARM ADVECTION AND THERMAL RIBBON LIFTING ACROSS THE
AREA WILL CREATE AN ARC OF CLOUDS ORIENTED NW-SE TO SHIFT NEWRD
ACROSS THE AREA. HAVE INCREASED SKY COVER A BIT FOR SUNDAY...SOME
FLURRIES MAY BE POSSIBLE BUT HAVE NOT INCLUDED THEM IN THE
FORECAST.
FAIRLY INTERESTING TROUGH TO SHIFT INTO THE AREA MONDAY. THE
TROUGH IS CURRENTLY IN THE ERN PACIFIC APPROACHING 47N/140W PER
GOES WATER VAPOR. MODEL GUIDANCE CONSENSUS FROM 15.12Z IS THAT
THERE WILL NRN AND SRN ENERGY IN THIS TROUGH. THE SRN PIECE OF
ENERGY IS HANDLED DIFFERENTLY BY THE LATEST GUIDANCE. THE 15.12Z
NAM/SREF DEVELOP ONLY A WEAK CYCLONE VIA THE SRN ENERGY...WHILE THE
GEM GLOBAL AND 15.00Z FIM MODEL ARE AGGRESSIVE WITH THE CYCLONE
DEEPENING IT ALONG A KANSAS CITY TO MILWAUKEE TRACK...AND DROPPING
A 4-8 INCH SNOW BAND ACROSS WI. 15.12Z ECMWF/GFS ARE SIMILAR AND
OFFER A COMPROMISE BETWEEN THE TWO CAMPS WITH THE CYCLONE
DEEPENING LATER...INTO MICHIGAN. HAVE GONE WITH THIS COMPROMISE ON
TIMING AND INTENSITY.
MONDAY WILL SEE A GULF SURGE OF MOISTURE IN THE SOUTHERLY FLOW...
DEEPENING A SURFACE-BASED LAYER TO OVER 1 KM DEEP. THIS WILL BE
PRE-FRONTAL IN THE SOUTHERLY FLOW AND WITHOUT DEEP CLOUD AND
ICE...BUT ISENTROPIC LIFT OF 3-5 UB/S IN THE LAYER ...DZ/FZDZ
WILL BE POSSIBLE. THE MOIST TONGUE IS MAINLY IN WI AND EAST AND
THAT IS WHERE DZ/FZDZ CHANCES WILL BE BEST. TEMPERATURES WILL BE
WARMING MONDAY WITH ABOVE FREEZING HIGHS AROUND I-90 AND SOUTH
EXPECTED. THUS...DZ OR RAIN SHOWERS COULD BE FREEZING IN THE EARLY
AFTERNOON IF ROADS DO NOT RESPOND TO WARMING. WITH QPFS LESS THAN
0.10 INCHES...WOULD EXPECT ONLY LIGHT ICING TO OCCUR. AS TROUGH
SHIFTS EAST LATE MONDAY AND MONDAY EVENING...A TRANSITION TO SNOW
WILL OCCUR FROM WEST TO EAST WITH SNOW AMOUNTS OF LESS THAN AN
INCH. HAVE INCREASED PRECIPITATION CHANCES OVERALL...BUT WI LOOKS
TO BE THE MAIN WEATHER AREA FOR THIS SYSTEM. THERE IS A CHANCE
THIS COULD NEED AN ADVISORY IF FREEZING PRECIPITATION LOOKS MORE
WIDESPREAD OR THE MORE AGGRESSIVE CYCLONE SOLUTION IN THE GEM
SHOULD BECOME MORE PROBABLE. THE SPREAD IN THE CYCLOGENESIS SEEN
FROM THE SRN ENERGY IN THE MODEL GUIDANCE SUGGESTS THIS IS AN
UNSTABLE SYSTEM AND COULD LEAD TO FORECAST CHANGES. WILL TAKE A
STEP UP IN OUR FORECAST VISIBILITY OF THIS SYSTEM.
.LONG TERM...TUESDAY THROUGH FRIDAY
319 PM CST FRI FEB 15 2013
ACTIVE EXTENDED PERIOD SETTING UP WITH THE FOCUS ON A SHORT ARCTIC
INTRUSION MID WEEK FOLLOWED BY THE POTENTIAL OF A WINTER STORM TO
IMPACT THE UPPER MIDWEST NEXT THURSDAY NIGHT AND FRIDAY.
GOING INTO TUESDAY...A LOT DEPENDS ON THE EVOLUTION AND PHASING OF
THE STORM SYSTEM THAT IS EXPECTED TO TRACK THROUGH MONDAY AND MONDAY
NIGHT...AND HOW MUCH ARCTIC AIR IS PULLED SOUTH IN ITS WAKE. 15.12Z
GUIDANCE SHOWS SIMILAR SOLUTIONS FOR 850 MB TEMPERATURES TO PLUMMET
AS LOW AS -15C TO -20C TUESDAY AND WEDNESDAY. STANDARDIZED
ANOMALIES FOR THIS PERIOD RANGE FROM 1 TO 1.5 BELOW NORMAL AND WITH
BROAD CYCLONIC FLOW ALOFT...IT WILL MAKE FOR A COUPLE COLD WINTER
DAYS. HIGHS IN THE TEENS AND OVERNIGHT LOWS IN THE SINGLE DIGITS
ABOVE ZERO...WITH OCCASIONAL LIGHT SNOW OR FLURRIES TUESDAY.
THE COLD AIRMASS SETS THE STAGE FOR LATER IN THE WEEK AS A WESTERN
CONUS TROUGH DEEPENS AND MOVES EAST. AS HAS BEEN ALLUDED TO IN
PREVIOUS DISCUSSIONS...THE RUN-TO-RUN AND MODEL CONSISTENCY FOR
THIS FEATURE REMAINS VERY HIGH. DETERMINISTIC MODELS STILL POINT
FOR A SURFACE LOW TRACK THROUGH THE CENTRAL PLAINS TO NORTHERN
ILLINOIS BY 12Z FRIDAY BRINGING WIDESPREAD PRECIPITATION TO THE
ENTIRE AREA WITH A CLASSIC DEFORMATION BAND OF SNOW SETTING UP.
LOOKING AT THE 15.12Z GFS ENSEMBLE...SURFACE LOW TRACK LOCATIONS
VARY FROM EASTERN IOWA...SOUTHERN WISCONSIN...AND ILLINOIS.
SIMILAR IDEAS ARE FOUND IN THE 15.00Z ECMWF ENSEMBLE. THE
STABILITY AND LACK OF SPREAD WITHIN THE NUMERICAL GUIDANCE FOR
THIS WEATHER SYSTEM ARE VERY HIGH.
ONE ISSUE THAT MAY PRECLUDE THIS FROM BEING A MORE SIGNIFICANT EVENT
IS THAT THE BOTH THE UPPER LEVEL AND SURFACE WAVES APPEAR TO BE
WEAKENING AS IT APPROACHES THE UPPER MIDWEST. 500 MB STANDARDIZED
ANOMALIES DROP FROM -2.5 ACROSS KANSAS TO BARELY BELOW NORMAL AS IT
CROSSES THE AREA. THIS IS REFLECTED IN THE SURFACE LOW PRESSURE
WHICH REMAINS AROUND 1000 MB THROUGHOUT. EARLIER RUNS SHOWED DEEPER
CYCLOGENESIS WITH 980-990 MB LOWS. THE 15.12Z ECMWF REALLY DAMPENS
OUT THE UPPER LEVEL AND SURFACE WAVE...BECOMING ALMOST OCCLUDED BY
FRIDAY AFTERNOON.
TEMPERATURE PROFILES ACROSS THE AREA CONTINUE TO SHOW AN ALL SNOW
EVENT...THOUGH THERE IS A SLIGHT WARMING TREND NOTED. IF THE
SYSTEM WERE TO DEEPEN AND WRAP UP MORE...THEN A PUSH OF WARMER AIR
COULD PRESENT A RAIN/SNOW MIX BUT RIGHT NOW THIS IS NOT THE CASE.
HAVE TRENDED PRECIPITATION CHANCES ABOVE MODEL CONSENSUS THURSDAY
NIGHT GIVEN CONTINUED EXCELLENT MODEL AGREEMENT AND THE SLOWER
TIMING OF THE SYSTEM.
ALTHOUGH IT IS A BIT TOO EARLY TO SPECULATE ON AMOUNTS...25.12Z GFS
ENSEMBLE AND 25.12Z ECMWF SHOW WIDESPREAD AMOUNTS OF 0.50 TO 0.75
INCHES OF LIQUID. SNOW RATIOS ARE NOT VERY HIGH...MOST LIKELY A BIT
BELOW CLIMATOLOGICAL VALUES /10 TO 12:1/ SO IN SHORT...WARNING
LEVEL /6 INCHES/ SNOW TOTALS COULD BE MET OR EXCEEDED ACROSS PARTS
OF THE REGION.
&&
.AVIATION...THROUGH 06Z SUNDAY
1048 PM CST FRI FEB 15 2013
CONFIDENCE HAS INCREASED THAT MVFR STRATUS WILL AFFECT THE TAF
SITES THIS MORNING. AN AREA OF MVFR STRATUS WAS PRESENT OVER
WESTERN MINNESOTA...JUST TO THE EAST OF A HIGH PRESSURE RIDGE IN
EASTERN SOUTH DAKOTA. THIS STRATUS HAS BEEN MOVING EASTWARD AND
EXPANDING. EXTRAPOLATION ALONG WITH NAM/RAP MODEL FORECASTS BRING
THE STRATUS INTO KRST AROUND 10Z AND KLSE AROUND 12Z. FLURRIES
HAVE ALSO BECOME MORE PREVALANT WITHIN THE STRATUS...AND WITH THE
CONFIDENCE NOW HIGHER ABOUT THE STRATUS AFFECTING THE TAF SITES...
ADDED -SHSN BACK IN. THE CLEARING TIME OF THE STRATUS IS STILL A
LITTLE UNCERTAIN...BUT GIVEN THAT THE WEST SIDE OF THE STRATUS
BANK IS MOVING AND DAYTIME MIXING WILL HELP OUT...GIVES CONFIDENCE
THE STRATUS DECK WILL NOT GET STUCK. HAVE KEPT THE 20Z TIME FOR
SCATTERING OUT OF THE CLOUDS...IN AGREEMENT TOO WITH THE NAM MODEL
FORECAST. CLEAR SKIES SHOULD DOMINATE MUCH OF THE EVENING AS THE
RIDGE OF HIGH PRESSURE BECOMES FIRMLY IN CONTROL. EXPECT WINDS TO
GENERALLY REMAIN LIGHT...LESS THAN 10 KT...DUE TO THE HIGH
PRESSURE RIDGE BUILDING IN.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
319 PM CST FRI FEB 15 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...TAYLOR/BAUMGARDT
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
836 AM EST SAT FEB 16 2013
.UPDATE...
WK BUT DISTINCT MESOLOW WHICH SPUN UP INVOF OF PARENT SFC TROUGH NR
KMKG ARND 0930Z CONTS TO CURL ESE THIS MORNING AND CURRENTLY WEST OF
KBTL. UPSTREAM CVRG BAND WHILE NOT AS INTENSE AS EARLIER XPCD TO
REINTENSIFY THROUGH LT MORNING ALG A KBIV...KAZO...KOEB LINE AS LK
AGGREGATE THERMAL TROUGHING STRENGTHENS AND UPSTREAM LK MSTR FLUX
MAXIMIZES INLAND. THIS MAY NECESSITATE A EWD EXPANSION OF CURRENT
ADVISORY OVR ST JOE MI TO INCLUDE BRANCH AND PERHAPS EVEN HILLSDALE.
TRENDING NR TERM RUC SOLUTIONS ADVERTISE A SIMILAR EVOLUTION AND
EVEN DIP FOCUSED BAND DOWN TO KTOL BY LT AFTN. HWVR GIVEN THINGS
STILL IN A STATE OF FLUX WILL CONT TO MONITOR DVLPMNTS AS PLACEMENT
ON LOCATION OF WRN FLANK STILL UNCERTAIN. OTRWS SIG UPSTREAM NEG
THETA-E ADVTN ASSOCD/W BLDG ARCTIC RIDGING LOOKS TO STIFLE ADDNL
SRN LAKE DVLPMNT UNTIL LT AFTN TIMED W/FURTHER AND MORE FVRBL LL
VEERING INTO SW MI/NW IN.
&&
.SHORT TERM... /TODAY THROUGH SUNDAY NIGHT/
PRIMARY FOCUS REMAINS ON LAKE EFFECT SNOW AMOUNTS AND IMPACTS ACROSS
FAR NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN TODAY THROUGH
SUNDAY MORNING...
A DIGGING UPPER TROUGH AXIS AND EMBEDDED SHORTWAVE ENERGY WILL PIVOT
THROUGH THE SOUTHERN GREAT LAKES REGION THIS MORNING WITH THE CORE
OF COLD AIR (7H TEMPS TO -28C) DROPPING THROUGH THIS AFTERNOON INTO
TONIGHT. THIS WILL RESULT IN EXTREME OVER-LAKE INSTABILITY WITH
IMPRESSIVE LAKE-7H TEMP DIFFERENTIALS NEAR 30C AND UVM/MOISTURE
MAXIMIZED WITHIN THE DGZ THROUGH THE EVENT. HOWEVER...MORE WESTERLY
300 DEGREE LOW LEVEL TRAJECTORIES AND A SUBSTANTIAL DIURNAL
COMPONENT TODAY WILL LIMIT ORGANIZATION (MORE CELLULAR) WITH DRY
UPPER MIDWEST ENTRAINMENT AND LARGE SCALE SUBSIDENCE BEHIND THIS
MORNING`S MID LEVEL WAVE ALSO LIMITING FACTORS FOR SIGNIFICANT SNOW
ACCUMS. THIS DRYING/POOR FETCH COMBO COULD EVEN RESULT IN A PERIOD
OF LITTLE/NO SNOW SHOWER ACTIVITY BY LATE MORNING/EARLY AFTERNOON.
THIS WILL LIKELY KEEP SNOW TOTALS IN CHECK THROUGH 00Z WITH
LOCATIONS NORTH OF HWY 6 IN INDIANA/MI STILL EXPECTING SNOW ACCUMS
BETWEEN 1 AND 4 INCHES. ELSEWHERE...EXPECT VERY COLD CONDITIONS WITH
ISOLATED TO SCATTERED SNOW SHOWERS POSSIBLE...ESPECIALLY EARLY THIS
MORNING ALONG THE SYNOPTIC TROUGH WITH DUSTING TO HALF INCH TYPE
ACCUMS POSSIBLE.
SLIGHT IN-CLOUD VEERING TO A MORE FAVORABLE 320-330 DEGREE
FETCH...LITTLE/NO SHEAR...AND FAVORABLE DIURNAL TIMING SHOULD
COMBINE TO ALLOW AN INTENSE SHORE PARALLEL SNOW BAND TO MATERIALIZE
WITHIN AN INTENSIFYING DIRECT THERMAL CIRCULATION/AGGREGATE SFC
TROUGH TONIGHT. HI-RES GUIDANCE CONTINUES TO SUGGEST MESOLOW
DEVELOPMENT WHICH WILL NO DOUBT DETERMINE WHERE THIS BAND SETS
UP/PIVOTS OVERNIGHT INTO EARLY SUNDAY MORNING. INTENSE SNOWFALL
RATES OF 2-3 INCHES PER HOUR WILL BE POSSIBLE WITHIN THIS BAND.
QUESTIONS OBVIOUSLY AT THIS JUNCTURE REMAIN EXACTLY WHERE THIS SETS
UP AND POSSIBLE INTERFERENCE (FLOW INTERRUPTION) FROM ANY MESOLOW. A
00Z MODEL CONSENSUS DOES FAVOR NORTHERN/EASTERN BERRIEN, WESTERN
CASS MI, AND ST JOE INDIANA AS THE PIVOT POINT WITH THE POTENTIAL
FOR SEVERAL HOURS OF HEAVY SNOW. FOR NOW WILL HOLD SERVE WITH
CURRENT HEADLINES GIVEN UNCERTAINTIES. REGARDLESS THERE IS THE
POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW MAINLY LATER THIS EVENING
INTO THE OVERNIGHT HOURS. ELSEWHERE...MAINLY DRY AND COLD.
WAA WITH RIDGING ALOFT AND BACKING LOW LEVEL TRAJECTORIES WILL BRING
ANY LINGERING LAKE EFFECT SNOW TO AN END BY EARLY SUNDAY AFTERNOON
WITH NO SENSIBLE WX CONCERNS SUNDAY AFTERNOON/NIGHT.
&&
.LONG TERM... /MONDAY THROUGH FRIDAY/
ALL IN ALL LITTLE SIG CHNG FM YDAY ANALYSIS WITH OVERALL INCRSD
CONFIDENCE WRT QPF/TIMING ASSOCD WITH LOW/MODERATE AMPLITUDE NRN
STREAM WAVE /CRNTLY APPROACHING PAC NW/ TO MAINTAIN PROGRESSIVE
NATURE INTO ERLY NEXT WEEK. SYSTEM TRAVERSING SCNTL CAN/NRN PLAINS
MONDAY TO SLOW TUESDAY/INCRSGLY VERTICALLY STACKED AS SRN END/SE CO
FNTL WAVE PROCEEDS INTO OCCLUSAL IN NRN GRTLKS. SOME
DISCOUNT/CAUTION TO THE MORE RAPID NAM/SREF SIGNALS...PER VARIANCE
AS NOTED IN PMDHMD. AT SAME TIME DIFFICULT TO UNDERESTIMATE
SHALLOW/DRY/COLD CP AIR ADVANCE AFFORDED BY POLEWARD CONNECTIVITY AT
SFC/LLVLS OF SUCH INTENSE NRN MANITOBA ANTICYCLONE. ATTEMPT TO
FURTHER DETAIL TIMING OF RAFL ONSET THROUGH CWA WITH SIGNALS OF DEEP
MSTR/UVM HOLDING OFF TIL LATE IN DAY ONCE LATE OPEN GOMEX FEED/NRN
TERMINUS OF HIGHLY INTENSE 925-8H LLJ TO 65 KTS AIMING FM MO
BOOTHILL THROUGH MOUTH OF OH RVR INTO FAR SWRN IN TO DEMAND FORCED
MOIST ASCENT...MOST LIKELY UNTIL LATE AFTN/21 UTC MON TIMEFRAME.
RAPID EWD SHIFT OF FEATURE INTO UPR OH VLY BY 06 UTC TO GRTLY LIMIT
UVM ACRS RGN AFT RAFL SLUG...WITH TRANSITION TO LIGHTER RA/SN MIX TO
SN THROUGH THE NIGHT WITH LITTLE/NO ACCUMS.
THEREAFTER...MINOR LES RESPONSE PER WRLY FLOW AND MUTED MIXED LYR
DEPTH. ALL EYES RMN ON LATE WEEK SYSTEM. SLIGHT NWD SHIFT SFC/ALOFT
NOTED PER MULTIMODEL CONSENSUS...THOUGH CERTAINLY NOT SIG ENOUGH TO
DISMISS. INTMTN/SWRN STATES TROF AT APEX 00 UTC THU/F120. THEREAFTER
HOLD DOUBTS AS TO EXACT TRACK. LOW AMPLITUDE/WEAKNESS NOTED IN
DOWNSTREAM RIDGE THEREAFTER AS SYSTEM EJECTS FM ERN NM INTO CNTL
PLAINS DY6. THIS DOWNSTREAM WEAKNESS COULD AFFORD POTNL TO BIFURCATE
AND MAINTAIN A MORE EWD MOMENTUM INTO DY7. ALSO TREND TWRDS CPC 8-14
ANALOGS COULD SUGGEST A POTNL REXING OF SYSTEM PER WEAK/ANTECEDENT
SRN CANADA/JAMES BAY RIDGE AIDED BY A POS HGHT ANOMOLY PHASE
THEREAFTER INTO DY8. POTNL STILL HOLDS OUT AS BEST SYNOPTIC SYSTEM
SINCE DEC 26 AS THU NIGHT ONSLAUGHT OF INITIAL STRONG ISENT
LIFT/STRONG EVAP/STRONGER DYNAMIC COOLING PROCESSES TO ELICIT RAPID
WETBULB COLLAPSE FOR SN/PSBLY BECMG HVY ACRS SWRN/WRN CWA BY ERLY
FRI. THEREAFTER A DOWNSTREAM RIDGE SPLIT/REX DVLPMNT REMOTELY COULD
OFFER A STALLED DEEP SYSTEM TO SLOWLY WITHER ON VINE ACRS NRN IN/SRN
LWR MI...AT LEAST THROUGH HERO FCSTR EYES. LARGE STANDARD DEVIATION
SPREAD PER MEDIUM RANGE MODEL ACCUMULATIONS. SAN COMPACTION WITH
CLIMATOLOGICAL MEAN NEAR 14/1 RATIOS USED AFFORDED RANGES GNRLY
WITHIN 3-7 INCH RANGE...FWIW AT F144-180.
&&
.AVIATION... /06 UTC TAFS/
LAKE EFFECT SNOW SHOWERS WILL IMPACT SBN THROUGH THE
PERIOD...ESPECIALLY THIS MORNING AND AGAIN SATURDAY NIGHT. THIS
WILL RESULT IN VARIABLE FLIGHT CONDITIONS THROUGH THE PERIOD.
THERE COULD BE A LULL IN THE SNOW SHOWER ACTIVITY LATER THIS
MORNING INTO THE EARLY AFTERNOON AS SUBSIDENCE/DRYING BUILDS IN
BRIEFLY BEHIND THIS MORNING`S WEAK MID LEVEL SHORTWAVE. AN INTENSE
SINGLE BAND MAY SET UP OVER SBN SATURDAY NIGHT WITH LIFR CONDITIONS
AND INTENSE 1-3 INCH PER HOUR SNOWFALL RATES POSSIBLE. EXPECT
MAINLY DRY/VFR CONDITIONS AT FWA...ALTHOUGH CANNOT RULE OUT A FEW
SNOW SHOWERS THROUGH THE PERIOD WHICH COULD BRIEFLY REDUCE
VISBYS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST /3 AM CST/ SUNDAY FOR
INZ003>005.
MI...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST SUNDAY FOR MIZ079.
LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SUNDAY FOR MIZ077-078.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...STEINWEDEL
LONG TERM...MURPHY
AVIATION...STEINWEDEL
UPDATE...T
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
901 AM EST SAT FEB 16 2013
.SYNOPSIS...
ISSUED AT 330 AM EST SAT FEB 16 2013
OCCASIONAL SNOW SHOWERS WILL CONTINUE TODAY AND INTO THIS EVENING.
THE SNOW WILL BE HEAVY AT TIMES. LAKE SHORE AREAS WILL PICK UP
ANOTHER 2 TO 4 INCHES...WHILE INLAND AREAS SEE 1 TO 2 INCHES. THE
SNOW IS EXPECTED TO DIMINISH AFTER MIDNIGHT.
BY MONDAY LOW PRESSURE WILL MOVE INTO THE UPPER MIDWEST. THIS
SYSTEM WILL BRIEFLY BRING TEMPERATURES UP TO AROUND 40 BY MONDAY
AFTERNOON. A PERIOD OF RAIN IS EXPECTED MONDAY AFTERNOON...THAT
WILL TURN TO SNOW MONDAY NIGHT AND CONTINUE ON TUESDAY. MORE SNOW
LOOKS LIKELY BY THURSDAY NIGHT AND FRIDAY.
&&
.UPDATE...
ISSUED AT 900 AM EST SAT FEB 16 2013
AFTER FURTHER CONSIDERATION...WILL BE UPGRADING MASON AND OCEANA
TO A WARNING. RAP GUIDANCE SUGGESTS THAT AFTER A LULL THIS MORNING...
ANOTHER SIGNIFICANT BAND MAY EXTEND FROM THESE COUNTIES THROUGH
MUSKEGON...ALLEGAN...AND KALAMAZOO COUNTIES.
UPDATE ISSUED AT 848 AM EST SAT FEB 16 2013
HAVE RECEIVED RECENT 8-12" SNOW REPORTS FROM SEVERAL LOCATIONS IN
MASON AND OCEANA COUNTIES BENEATH AN AREA OF SATELLITE IR
TEMPERATURES THAT WERE COLDER THAN -30C BETWEEN 11-12Z. 830 AM
AWOS OBSERVATION AT HART INDICATES VISIBILITY BELOW 1/4 MILE.
SUSPECT STRONG FRONTOGENETIC FORCING HAS BEEN AT PLAY AS
TEMPERATURES AT RQB AND CAD HAD DROPPED AS MUCH AS 10 DEGREES OR
MORE OVER THE PAST FEW HOURS. PRESENT THINKING IS THAT FGEN
FORCING SHOULD DECREASE ALONG WITH MOST INTENSE SNOW THROUGH 10
AM. THIS IS SUPPORTED BY THE 16/09Z RUN OF THE HRRR...WHICH TAPERS
PRECIP AND MOVES IT INLAND THROUGH 15Z. BELIEVING WE ARE ON A
DOWNWARD TREND AFTER A PEAK IN SNOWFALL INTENSITY...WILL KEEP THE
ADVISORY GOING IN THIS AREA AND UPDATE WITH THE LATEST THINKING.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 330 AM EST SAT FEB 16 2013
A RATHER DISORGANIZED PATTERN SO FAR EARLY THIS MORNING. A SURFACE
TROUGH HAS BEEN CROSSING THE LAKE EARLY THIS MORNING AND THE WIND
PATTERN AROUND THIS TROUGH HAS BEEN DISRUPTING ANY ORGANIZED LAKE
EFFECT BANDS. THERE HAS BEEN A PERSISTENT BAND ACROSS THE NW
COUNTIES NEAR LUDINGTON AND WHITEHALL...BUT OTHER SNOW BANDS HAVE
BEEN FAIRLY TRANSITORY...KEEPING ACCUMS DOWN.
THE SURFACE TROUGH LINGERS OVER THE AREA MUCH OF TODAY...SO FEEL WE
MAY STRUGGLE TO GET PERSISTENT LES BANDS. RAP13 LOW LEVEL
CONVERGENCE FIELDS SUGGEST THE LDM BAND MAY HOLD PAT MUCH OF THE
DAY. IF THIS HOLDS TRUE...THIS BAND COULD PUT DOWN ANOTHER FOUR
INCHES OR SO. A BETTER FLAIR UP IS INDICATED TOWARD 16Z FOR THE SW
COUNTIES AND THIS IS PAINTED TO LAST THROUGH MUCH OF THE AFTERNOON.
ALSO OF INTEREST IS A SYNOPTIC CONVERGENCE BAND THAT FLAIRS UP NORTH
OF THE SURFACE TROUGH ALONG HIGHWAY 10 BY MID TO LATE AFTERNOON
TODAY. IF THIS HOLDS TRUE THERE COULD BE A BURST OF SNOW ACROSS ALL
OF THE NORTHERN COUNTIES INTO THIS EVENING.
NEEDLESS TO SAY A RATHER COMPLEX PATTERN FOR TODAY. THOUGHT ABOUT
DROPPING SOME OF THE COUNTIES IN THE ADVISORY AS THE LAKE EFFECT
DOES NOT LOOK AS ROBUST ANYMORE. HOWEVER SINCE SNOW WILL STILL
OCCUR...IT IS SORT OF HARD TO DROP HEADLINES IN THE MIDDLE OF AN
EVENT. SO WILL LEAVE THE ADVISORY AS IS...ALTHOUGH WILL HIGHLIGHT
SLIGHTLY LESS ACCUMS. ON THE OTHER HAND...INLAND AREAS COULD SEE A
BIT MORE SNOW THEN WHAT IS CURRENTLY IN THE FORECAST DUE TO THE
SYNOPTIC FEATURES. SO HAVE BUMPED UP ACCUMS A BIT INLAND...
ESPECIAL NEAR HIGHWAY 10 TO COVER THE POSSIBLE CONVERGENCE BURST
LATE TODAY INTO THIS EVENING. THE SNOW SHOULD BE DWINDLING AFTER
MIDNIGHT AS THE SYSTEM PULLS AWAY AND INVERSION LEVELS COME DOWN.
WILL CONTINUE WITH THE CHANCE POPS ON SUNDAY ALONG THE LAKE SHORE.
WINDS WILL PIVOT FROM THE NNW EARLY IN THE DAY TO SW TOWARD MID
DAY. THIS SHOULD PUSH ANY LAKE BAND INLAND...PRODUCING A BRIEF SNOW
SHOWER MAINLY WEST OF U.S. 131.
THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE MONDAY SYSTEM...
BRINGING IT IN QUICKER. HAVE INCREASED POPS TO LIKELY BY MID TO
LATE AFTERNOON. SHOULD BE WARM ENOUGH OF MOSTLY RAIN...ALTHOUGH A
MIX SHOULD FALL OVER CENTRAL LOWER.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EST SAT FEB 16 2013
ACTIVE WEATHER PATTERN NEXT WEEK WITH TWO STORMS TO WATCH. A CLIPPER
MOVES MOVES EAST MONDAY NIGHT WITH RAIN AND SNOW MIX CHANGING TO
SNOW...FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY AFTERNOON
INTO WEDNESDAY.
SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON
WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM TAKES
SHAPE ACROSS THE PLAINS AND MOVES NORTHEAST SPREADING A BAND OF SNOW
INTO LOWER MICHIGAN BY LATE THURSDAY. SNOW COULD BE HEAVY THURSDAY
NIGHT AS AN AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP LIFT
MOVES OVER LOWER MICHIGAN. SNOW WILL CONTINUE ON FRIDAY AS AN UPPER
LOW MOVES ACROSS ALTHOUGH WITH LESS INTENSITY AS DEEPER LIFT AND
MOISTURE MOVES EAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 651 AM EST SAT FEB 16 2013
LAKE EFFECT SNOW SHOWERS WILL BRING AREAS OF IFR AND PATCHY LIFR
TODAY. CONDITIONS WILL VARY QUITE A BIT WITH VFR AND MVFR
PREVAILING WELL INLAND. WINDS WILL BE NORTHWEST AT OR BELOW 10
KNOTS. THE SNOW WILL BEGIN TO LET UP THIS EVENING WITH MOSTLY VFR
EXPECTED LATER TONIGHT.
&&
.MARINE...
ISSUED AT 330 AM EST SAT FEB 16 2013
WILL KEEP MARINE HEADLINE AS IS...SCA THROUGH TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 330 AM EST SAT FEB 16 2013
COLDER AIR HAS LOCKED UP ANY FURTHER SNOW MELT. WE WILL SEE A BRIEF
WARM UP ON MONDAY WITH TEMPS REACHING AROUND 40 ALONG WITH SOME
RAIN. SINCE THE WARM UP WILL BE BRIEF AND THE RAIN SHOULD BY LESS
THAN A QUARTER INCH...NO HYDRO ISSUES ARE EXPECTED. HOWEVER A FLOOD
ADVISORY REMAINS IN EFFECT FOR HIGH WATERS ON THE PERE MARQUETTE
NEAR SCOTTVILLE.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR
MIZ037-043-050-056-064-071-072.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ038-
044-057-065-073.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...OSTUNO
AVIATION...OSTUNO
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
642 AM CST SAT FEB 16 2013
.UPDATE...
.SHORT TERM...
MULTI MODEL BLEND OF RUC...HRRR...GEMREG...SREF...NAM...ECM
PRODUCED WARMER TEMPS TODAY AND SUNDAY AS WARRANTED BY THE KUNR
SOUNDING. NO DISCERNIBLE CHANGE OCCURRED TO THE ONGOING WEATHER
USING THE SAME BLEND. A NEW FCST IS OUT...KIML COULD REACH 60F ON
SUNDAY. OVERALL THE SNOW MOVES OUT QUICKLY THIS MORNING WITH
CLEARING TO FOLLOW JUST A RAPIDLY ALONG AND WEST OF HIGHWAY 83.
CLOUDS STAY IN LONGER EAST OF 83 AS ANOTHER BATCH OF CLOUDS MOVES
DOWN FROM THE DAKOTAS LATER THIS MORNING.
.PREV DISCUSSION... /ISSUED 515 AM CST SAT FEB 16 2013/
UPDATE...
AVIATION...
MVFR IN SNOW AND LOW CIGS WILL MOVE SLOWLY EAST TODAY. THE RUC AND
NAM KEEP MVFR CIGS IN PLACE FROM KVTN-KTIF EAST THROUGHOUT THE
AFTN EVEN AFTER THE SNOW ENDS WHILE THE GFS OPENS UP THE AREA TO
VFR BY 18Z ONCE THE SNOW MOVES OUT. THE FCST FOLLOWS THE GFS...THE FASTER
SOLNS. THE GENERAL FEELING IS ONCE THE SNOW ENDS...CIGS WILL
IMPROVE TO VFR.
VFR IS EXPECTED ALL AREAS TONIGHT IF THE GFS VERIFIES.
PREV DISCUSSION... /ISSUED 413 AM CST SAT FEB 16 2013/
UPDATE...
SHORT TERM...
RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING
LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS
STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS
LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS
OVER AN OBSERVATION SITE.
THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A
SPECIAL WEATHER STATEMENT.
PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/
SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR
SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS
MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE
DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT
BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING
HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S
SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20.
LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED
PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER
STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY.
CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG
SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD.
MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD
EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE
ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW
LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE
THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS
THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT
GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F
OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL
SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING
BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW
TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE
ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN
HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL
NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR
SOUTHWEST.
ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY
NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG
UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY
NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL
BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH
A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE
HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING
PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF
25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO
SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH
EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS
LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER
TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY
TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS
INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA
FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST
AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR
PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE.
THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY
THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE
LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC
WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH
DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND
EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT
KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF
THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE
INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE.
AVIATION...
SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING
INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND
EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE
LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT
THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN
EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE
INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE
TIME BEING.
IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE LIKELY
TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO VISIBILITY.
WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320
AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST
SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP
OF THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED
CHANGE OF ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT
THIS TIME... IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE
THRESHOLD ALTITUDE OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN
THE TERMINAL FORECAST FOR LBF. THE TIME OF THE GREATEST RISK OF
LOW LEVEL WIND SHEAR WILL BE 12-15Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION....CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
515 AM CST SAT FEB 16 2013
.UPDATE...
.AVIATION...
MVFR IN SNOW AND LOW CIGS WILL MOVE SLOWLY EAST TODAY. THE RUC AND
NAM KEEP MVFR CIGS IN PLACE FROM KVTN-KTIF EAST THROUGHOUT THE
AFTN EVEN AFTER THE SNOW ENDS WHILE THE GFS OPENS UP THE AREA TO
VFR BY 18Z ONCE THE SNOW MOVES OUT. THE FCST FOLLOWS THE GFS...THE FASTER
SOLNS. THE GENERAL FEELING IS ONCE THE SNOW ENDS...CIGS WILL
IMPROVE TO VFR.
VFR IS EXPECTED ALL AREAS TONIGHT IF THE GFS VERIFIES.
&&
.PREV DISCUSSION... /ISSUED 413 AM CST SAT FEB 16 2013/
UPDATE...
SHORT TERM...
RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING
LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS
STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS
LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS
OVER AN OBSERVATION SITE.
THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A
SPECIAL WEATHER STATEMENT.
PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/
SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR
SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS
MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE
DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT
BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING
HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S
SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20.
LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED
PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER
STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY.
CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG
SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD.
MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD
EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE
ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW
LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE
THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS
THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT
GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F
OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL
SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING
BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW
TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE
ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN
HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL
NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR
SOUTHWEST.
ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY
NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG
UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY
NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL
BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH
A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE
HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING
PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF
25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO
SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH
EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS
LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER
TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY
TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS
INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA
FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST
AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR
PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE.
THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY
THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE
LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC
WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH
DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND
EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT
KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF
THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE
INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE.
AVIATION...
SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING
INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND
EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE
LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT
THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN
EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE
INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE
TIME BEING.
IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE LIKELY
TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO VISIBILITY.
WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320
AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST
SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP
OF THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED
CHANGE OF ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT
THIS TIME... IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE
THRESHOLD ALTITUDE OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN
THE TERMINAL FORECAST FOR LBF. THE TIME OF THE GREATEST RISK OF
LOW LEVEL WIND SHEAR WILL BE 12-15Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION....CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
413 AM CST SAT FEB 16 2013
.UPDATE...
.SHORT TERM...
RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING
LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS
STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS
LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS
OVER AN OBSERVATION SITE.
THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A
SPECIAL WEATHER STATEMENT.
.PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/
SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR
SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS
MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE
DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT
BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING
HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S
SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20.
LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED
PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER
STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY.
CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG
SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD.
MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD
EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE
ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW
LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE
THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS
THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT
GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F
OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL
SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING
BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW
TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE
ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN
HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL
NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR
SOUTHWEST.
ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY
NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG
UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY
NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL
BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH
A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE
HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING
PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF
25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO
SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH
EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS
LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER
TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY
TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS
INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA
FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST
AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR
PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE.
THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY
THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE
LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC
WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH
DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND
EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT
KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF
THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE
INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE.
AVIATION...
SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING
INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND
EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE
LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT
THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN
EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE
INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE
TIME BEING.
IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE LIKELY
TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO VISIBILITY.
WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320
AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST
SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP
OF THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED
CHANGE OF ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT
THIS TIME... IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE
THRESHOLD ALTITUDE OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN
THE TERMINAL FORECAST FOR LBF. THE TIME OF THE GREATEST RISK OF
LOW LEVEL WIND SHEAR WILL BE 12-15Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION....CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1032 AM EST SAT FEB 16 2013
.SYNOPSIS...
A COLD ARCTIC AIRMASS WILL FILTER INTO THE REGION TODAY WITH SOME
SCATTERED LIGHT LAKE EFFECT SNOWS SOUTH OF THE LAKES. THE COLDEST
AIR WILL ARRIVE ACROSS THE REGION SUNDAY AS A STRONG STORM SYSTEM
MOVES ALONG THE NEW ENGLAND COAST. TEMPERATURES WILL ONLY RISE INTO
THE TEENS SUNDAY. MONDAY A MODEST WARMING TREND BEGINS AHEAD OF THE
NEXT STORM TO IMPACT THE AREA WITH A WINTRY MIX MONDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
THROUGH MID-MORNING...A WEAK AREA OF HIGH PRESSURE EXTENDS
ACROSS EASTERN LAKE ONTARIO...WITH AN UPPER LEVEL TROF AXIS TO THE
WEST ACROSS MICHIGAN. THERE ARE A COUPLE OF ILL-DEFINED FRONTAL
BOUNDARIES IN THE MIX. A CONVERGENT FLOW ON LAKE ONTARIO CAN ALSO
BE SEEN...PROBABLY DUE TO A LEFT OVER FRONTAL BOUNDARY...OR LAKE
CONVERGENCE DUE TO THE LOCALLY WARMER TEMPERATURES.
RADAR TREND SHOW AN EXPANSION OF SNOW SHOWERS ACROSS LAKE
ERIE...WITH CONTINUED SNOW SHOWERS ON THE OPEN WATERS OF LAKE
ONTARIO. WHILE THE LATTER IS FORECAST TO REMAIN OUT ON THE
WATERS...THE APPROACHING UPPER TROF IS LIKELY TO PUSH THE SNOW
SHOWERS ON LAKE ERIE ONSHORE. A CONSENSUS OF THE 12Z NAM/00Z
RGEM/12Z HRRR ALL SHOW SOME LIGHT QPFS ASSOCIATED WITH THIS DURING
THE AFTERNOON HOURS. BASED ON THE UPPER PATTERN...WHICH WILL SHIFT
BOUNDARY LAYER WINDS TO THE WEST...THESE SOLUTIONS MAKE SENSE.
BECAUSE OF THIS...WILL UP POPS TO LIKELY WEST OF ROCHESTER THIS
AFTERNOON. THIS SAID...BECAUSE OF THE TRANSIENT NATURE OF THIS
FEATURE...EXPECT ONLY LIGHT ACCUMULATIONS. WINDS WILL BE TOO
SHEARED FOR MUCH IN THE WAY OF ORGANIZED BANDS. THERE IS SOME
INDICATION BY THE HRRR THAT BRIEF PERIOD OF MODERATE SNOW SHOWERS
WILL DEVELOP...BUT ITS HARD TO SAY WHERE THESE WOULD OCCUR GIVEN
VARIABILITY IN MODEL RUNS. THE FAST MAJORITY OF LOCATIONS WILL GET
LESS THAN AN INCH...WITH AN INCH OR TWO POSSIBLE IN HEAVIER SNOW
SHOWERS. DO EXPECT A GOOD FLUFF FACTOR GIVEN 850 MB TEMPS OF -16C
AS SHOWN ON OUR MORNING SOUNDING.
EAST OF LAKE ONTARIO SHOULD REMAIN DRY...WITH A FAIR AMOUNT OF
SUNSHINE. EXPECT HIGHS IN THE LOWER TO MID 20S IN MOST LOCATIONS.
TONIGHT...THE WEAK SURFACE LOW WILL BE ABSORBED INTO THE
STRENGTHENING STORM SYSTEM TRACKING NORTH OFF THE EAST COAST. AS
THIS OCCURS MUCH COLDER AIR WILL ARRIVE UNDER NORTHWEST WINDS. THE
CORE OF THE UPPER LEVEL TROUGH...COLD POOL ALOFT...WILL SHIFT OVER
WESTERN NY. TEMPERATURES WILL PLUMMET THROUGH THE TEENS INTO THE
SINGLE DIGITS MAKING FOR A VERY COLD NIGHT. WINDS WILL BE FAIRLY
LIGHT SO NO THREAT FOR MUCH OF AN IMPACT FROM WIND CHILLS. THE NAM
AND RGEM MODELS SHOW THAT SOME LAKE LAKE EFFECT COULD BECOME
ORGANIZED EAST OF LAKE ERIE WITH NORTHWEST WINDS ALIGNING AND 850 MB
TEMPS DROPPING TO AROUND -18C. ACCUMULATIONS ACROSS THE SOUTHERN TIER
COULD BE IN THE TWO TO THREE INCH RANGE. ORGANIZED ACTIVITY OFF LAKE
ONTARIO WILL HOLD OFF UNTIL SUNDAY.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
A WELL ALIGNED NORTHWEST OF COLDER AIR WILL SET UP ACROSS THE LOWER
LAKES ON SUNDAY IN THE WAKE OF THE DEEP UPPER LEVEL TROUGH THAT WILL
SLIDE EAST INTO NEW ENGLAND. WHILE THE DEEPER SYNOPTIC SCALE
MOISTURE WILL SHIFT EAST INTO NEW ENGLAND...ENOUGH LOW LEVEL
MOISTURE WILL REMAIN WITHIN WITH THE LAYER OF FAVORABLE SNOW GROWTH.
THIS WILL RESULT IN BETTER ORGANIZED LAKE EFFECT SNOW SOUTHEAST OF
BOTH LAKES. IT STILL LOOKS LIKE SNOW ACCUMULATIONS WILL STAY BELOW
ADVISORY CRITERIA DUE TO THE SHORT FETCH ACROSS THE LAKES AND THE
UNCERTAINTY REGARDING CONTRIBUTIONS OF MOISTURE FROM UPSTREAM LAKES.
EXPECT THE HIGHEST ACCUMULATIONS TO BE ALONG THE CHAUTAUQUA RIDGE
AND SOUTHEAST OF LAKE ONTARIO...FROM WAYNE TO SOUTHERN OSWEGO
COUNTIES. AREAS OUTSIDE OF THE STEADIER LAKE EFFECT SNOW WILL SEE
PARTLY CLOUDY SKIES WITH SOME FLURRIES. IT WILL BE RATHER COLD WITH
AREAS TEMPERATURES EXPECTED TO HOLD STEADY IN THE TEENS.
THE ONGOING LAKE SNOWS WILL DIMINISH SUNDAY NIGHT AS THE LOW LEVEL
MOISTURE DECREASES AND THE SUBSIDENCE INVERSION CONTINUES TO LOWER.
THIS WILL HAPPEN FIRST OFF LAKE ERIE...BUT THE WEAKENING LAKE
ONTARIO BANDS WILL PROBABLY REMAIN INTACT THROUGH MONDAY MORNING.
ON MONDAY...A WEAK SURFACE RIDGE WILL BE SANDWICHED BETWEEN LOW
PRESSURE OVER THE CANADIAN MARITIMES AND A SECOND LOW THAT WILL BE
ADVANCING EAST INTO THE UPPER MIDWEST. THE SOUTHERLY FLOW THAT SETS
UP BETWEEN THESE TWO SYSTEMS WILL ALLOW TEMPERATURES TO REBOUND TO
NEAR SEASONAL LEVELS...AFTER A COLD START TO THE DAY. ANY LAKE
EFFECT SNOW SHOWERS THAT LINGER SOUTHEAST OF LAKE ONTARIO SHOULD END
BY EARLY AFTERNOON.
AS THE UPPER MIDWEST LOW TRACKS EAST ACROSS THE CENTRAL GREAT LAKES
SUNDAY NIGHT...A POTENT LOW LEVEL JET WILL BE HEADING NORTHEAST
TOWARD THE LOWER GREAT LAKES. THE LOW LEVEL JET WILL TAP INTO DEEPER
MOISTURE OVER THE LOWER OHIO AND TENNESSEE VALLEYS AND ALLOW PCPN TO
SPREAD EAST ACROSS OUR CWA. STRONG WARM AIR ADVECTION ALOFT ON THE
NOSE OF THE LOW LEVEL JET WILL CREATE A TEMPERATURE PROFILE THAT
WILL SUPPORT A WINTRY MIX OF PRECIPITATION...INCLUDING THE
POSSIBILITY OF SLEET AND FREEZING RAIN. THE LATEST GUIDANCE
SUGGESTS THAT THE CORE OF THE LOW LEVEL JET AND WARMEST TEMPERATURES
ALOFT WILL SHIFT EAST INTO CENTRAL AND EASTERN NEW YORK DURING THE
SECOND HALF OF THE NIGHT. AS A RESULT...THE RISK FOR FREEZING RAIN
MAY BE GREATER ACROSS THESE AREAS.
EXPECT TEMPERATURES TO HOLD STEADY OR SLOWLY RISE MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE CENTRAL GREAT LAKES LOW WILL SHIFT EAST ACROSS SOUTHERN ONTARIO
AND SOUTHERN QUEBEC ON TUESDAY. A PAIR OF FRONTS TRAILING SOUTH OF
THE LOW WILL HAVE SOME IMPACT ON THE CWA. MIXED PCPN AT THE START OF
THE DAY MAY CHANGE TO RAIN DURING THE MORNING...BEFORE COLDER AIR
BUILDS IN DURING THE AFTERNOON AND CHANGES THE PCPN BACK TO SNOW.
AS THE COLDER AIR DEEPENS TUESDAY NIGHT...WIDESPREAD SNOW SHOWERS
WILL CONTINUE.
AS FOR ANY WIND POTENTIAL...THERE IS A LOW LEVEL JET FORECAST TO
MOVE INTO THE REGION...NEAR 60-70KTS. GFS BUFKIT MOMENTUM TRANSFER
INDICATES A SUB-WARNING RESPONSE AS THE COLD AIR WORKS ITS WAY INTO
WESTERN NY. THIS MAKES SENSE AS THE SURFACE LOW SHOULD BE NO LONGER
DEEPENING AS IT MOVES WELL TO THE NORTH...WITH A ONLY A SMALL
ISALLOBARIC WIND RESPONSE AS THE MAIN PRESSURE CHANGES WILL BE WELL
NORTH OF THE REGION.
ONCE THIS SYSTEM MOVES OUT OF THE REGION...EXPECT SCATTERED SNOW
SHOWERS AND POSSIBLE STEADIER LAKE EFFECT SNOW TO CONTINUE INTO
WEDNESDAY.
ANOTHER RIDGE MOVES PAST ON THURSDAY FOR DRY WEATHER.
THE NEXT SYSTEM ALSO APPEARS TO BE FAIRLY WELL HANDLED BY VARIOUS
GUIDANCE PACKAGES. THIS SYSTEM CAN CURRENTLY BE FOUND HEADING
EAST...JUST SOUTH OF THE ALEUTIAN ISLANDS ON SATELLITE IMAGERY.
MODELS TAKE THIS FEATURE AND CREATE A CUTOFF OVER THE DESERT
SOUTHWEST...AND THEN ACROSS THE PLAINS AND INTO THE GREAT LAKES
REGION ON FRIDAY. CUTOFFS ARE NOT WELL HANDLED BY MODELS...AND
OFTEN SLOWER MOVE EAST THAN MODEL FORECASTS. WILL FORECAST A CHANCE
OF PRECIPITATION WITH THIS FEATURE AS IT IS SEVEN DAYS OUT...BUT IT
MIGHT END UP REMAINING DRY FOR FRIDAY.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
THROUGH THE REMAINDER OF THE MORNING...EXPECT VFR CONDITIONS WITH
SCT-BKN CIGS ABOVE 3000 FEET. AFTER THIS...AN AREA OF SNOW SHOWERS
DEVELOPING ON EASTERN PORTIONS OF LAKE ERIE WILL GRADUALLY PUSH
EAST AND HAVE SOME IMPACT ON THE BUF/IAG/JHW/ROC TERMINALS. ANY
IMPACT SHOULD BE TEMPORARY IN NATURE...PROBABLY 1 TO 3 HOURS...BUT
DURING THIS TIME VSBY BELOW 2SM IS POSSIBLE. ART SHOULD REMAIN DRY
AND VFR.
THIS AREA WILL DISSIPATE THIS EVENING...BUT UPSLOPE SNOW SHOWERS
SHOULD EXPAND LATE TONIGHT...RESULTING IN LOWERING CIGS/VSBY SOUTH
OF LAKE ONTARIO. SNOWFALL RATES SHOULD GENERALLY BE ON THE LIGHT
SIDE AT MOST TAF LOCATIONS THROUGH 12Z.
OUTLOOK...
SUNDAY THROUGH SUNDAY NIGHT...VFR/MVFR WITH SCATTERED SNOW SHOWERS.
MONDAY...VFR.
TUESDAY...MVFR/IFR...RAIN CHANGING OVER TO SNOW LATE.
TUESDAY NIGHT THROUGH WEDNESDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT
SNOW SHOWERS.
&&
.MARINE...
A COLD FRONT WILL STALL OVER THE SOUTHERN SHORE OF LAKE ONTARIO
TODAY AS A WEAK SURFACE LOW TRACKS EAST ALONG THE BOUNDARY. THIS
WILL WILL RESULT IN LIGHT AND VARIABLE WINDS THROUGH MUCH OF TODAY.
NORTHWESTERLY WINDS WILL INCREASE SUNDAY AS COASTAL STORM SYSTEM
MOVES EAST OF NEW ENGLAND. THIS WILL LIKELY BRING ANOTHER ROUND OF
SMALL CRAFT ADVISORIES ALONG THE SOUTHERN LAKE ONTARIO SHORELINE.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SMITH
NEAR TERM...APFFEL/SMITH
SHORT TERM...TJP
LONG TERM...TJP/ZAFF
AVIATION...APFFEL/SMITH
MARINE...APFFEL/SMITH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
953 AM EST SAT FEB 16 2013
.SYNOPSIS...
A COLD ARCTIC AIRMASS WILL FILTER INTO THE REGION TODAY WITH SOME
SCATTERED LIGHT LAKE EFFECT SNOWS SOUTH OF THE LAKES. THE COLDEST
AIR WILL ARRIVE ACROSS THE REGION SUNDAY AS A STRONG STORM SYSTEM
MOVES ALONG THE NEW ENGLAND COAST. TEMPERATURES WILL ONLY RISE INTO
THE TEENS SUNDAY. MONDAY A MODEST WARMING TREND BEGINS AHEAD OF THE
NEXT STORM TO IMPACT THE AREA WITH A WINTRY MIX MONDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
THROUGH MID-MORNING...A WEAK AREA OF HIGH PRESSURE EXTENDS
ACROSS EASTERN LAKE ONTARIO...WITH AN UPPER LEVEL TROF AXIS TO THE
WEST ACROSS MICHIGAN. THERE ARE A COUPLE OF ILL-DEFINED FRONTAL
BOUNDARIES IN THE MIX. A CONVERGENT FLOW ON LAKE ONTARIO CAN ALSO
BE SEEN...PROBABLY DUE TO A LEFT OVER FRONTAL BOUNDARY...OR LAKE
CONVERGENCE DUE TO THE LOCALLY WARMER TEMPERATURES.
RADAR TREND SHOW AN EXPANSION OF SNOW SHOWERS ACROSS LAKE
ERIE...WITH CONTINUED SNOW SHOWERS ON THE OPEN WATERS OF LAKE
ONTARIO. WHILE THE LATTER IS FORECAST TO REMAIN OUT ON THE
WATERS...THE APPROACHING UPPER TROF IS LIKELY TO PUSH THE SNOW
SHOWERS ON LAKE ERIE ONSHORE. A CONSENSUS OF THE 12Z NAM/00Z
RGEM/12Z HRRR ALL SHOW SOME LIGHT QPFS ASSOCIATED WITH THIS DURING
THE AFTERNOON HOURS. BASED ON THE UPPER PATTERN...WHICH WILL SHIFT
BOUNDARY LAYER WINDS TO THE WEST...THESE SOLUTIONS MAKE SENSE.
BECAUSE OF THIS...WILL UP POPS TO LIKELY WEST OF ROCHESTER THIS
AFTERNOON. THIS SAID...BECAUSE OF THE TRANSIENT NATURE OF THIS
FEATURE...EXPECT ONLY LIGHT ACCUMULATIONS. WINDS WILL BE TOO
SHEARED FOR MUCH IN THE WAY OF ORGANIZED BANDS. THERE IS SOME
INDICATION BY THE HRRR THAT BRIEF PERIOD OF MODERATE SNOW SHOWERS
WILL DEVELOP...BUT ITS HARD TO SAY WHERE THESE WOULD OCCUR GIVEN
VARIABILITY IN MODEL RUNS. THE FAST MAJORITY OF LOCATIONS WILL GET
LESS THAN AN INCH...WITH AN INCH OR TWO POSSIBLE IN HEAVIER SNOW
SHOWERS. DO EXPECT A GOOD FLUFF FACTOR GIVEN 850 MB TEMPS OF -16C
AS SHOWN ON OUR MORNING SOUNDING.
EAST OF LAKE ONTARIO SHOULD REMAIN DRY...WITH A FAIR AMOUNT OF
SUNSHINE. EXPECT HIGHS IN THE LOWER TO MID 20S IN MOST LOCATIONS.
TONIGHT...THE WEAK SURFACE LOW WILL BE ABSORBED INTO THE
STRENGTHENING STORM SYSTEM TRACKING NORTH OFF THE EAST COAST. AS
THIS OCCURS MUCH COLDER AIR WILL ARRIVE UNDER NORTHWEST WINDS. THE
CORE OF THE UPPER LEVEL TROUGH...COLD POOL ALOFT...WILL SHIFT OVER
WESTERN NY. TEMPERATURES WILL PLUMMET THROUGH THE TEENS INTO THE
SINGLE DIGITS MAKING FOR A VERY COLD NIGHT. WINDS WILL BE FAIRLY
LIGHT SO NO THREAT FOR MUCH OF AN IMPACT FROM WIND CHILLS. THE NAM
AND RGEM MODELS SHOW THAT SOME LAKE LAKE EFFECT COULD BECOME
ORGANIZED EAST OF LAKE ERIE WITH NORTHWEST WINDS ALIGNING AND 850 MB
TEMPS DROPPING TO AROUND -18C. ACCUMULATIONS ACROSS THE SOUTHERN TIER
COULD BE IN THE TWO TO THREE INCH RANGE. ORGANIZED ACTIVITY OFF LAKE
ONTARIO WILL HOLD OFF UNTIL SUNDAY.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
A WELL ALIGNED NORTHWEST OF COLDER AIR WILL SET UP ACROSS THE LOWER
LAKES ON SUNDAY IN THE WAKE OF THE DEEP UPPER LEVEL TROUGH THAT WILL
SLIDE EAST INTO NEW ENGLAND. WHILE THE DEEPER SYNOPTIC SCALE
MOISTURE WILL SHIFT EAST INTO NEW ENGLAND...ENOUGH LOW LEVEL
MOISTURE WILL REMAIN WITHIN WITH THE LAYER OF FAVORABLE SNOW GROWTH.
THIS WILL RESULT IN BETTER ORGANIZED LAKE EFFECT SNOW SOUTHEAST OF
BOTH LAKES. IT STILL LOOKS LIKE SNOW ACCUMULATIONS WILL STAY BELOW
ADVISORY CRITERIA DUE TO THE SHORT FETCH ACROSS THE LAKES AND THE
UNCERTAINTY REGARDING CONTRIBUTIONS OF MOISTURE FROM UPSTREAM LAKES.
EXPECT THE HIGHEST ACCUMULATIONS TO BE ALONG THE CHAUTAUQUA RIDGE
AND SOUTHEAST OF LAKE ONTARIO...FROM WAYNE TO SOUTHERN OSWEGO
COUNTIES. AREAS OUTSIDE OF THE STEADIER LAKE EFFECT SNOW WILL SEE
PARTLY CLOUDY SKIES WITH SOME FLURRIES. IT WILL BE RATHER COLD WITH
AREAS TEMPERATURES EXPECTED TO HOLD STEADY IN THE TEENS.
THE ONGOING LAKE SNOWS WILL DIMINISH SUNDAY NIGHT AS THE LOW LEVEL
MOISTURE DECREASES AND THE SUBSIDENCE INVERSION CONTINUES TO LOWER.
THIS WILL HAPPEN FIRST OFF LAKE ERIE...BUT THE WEAKENING LAKE
ONTARIO BANDS WILL PROBABLY REMAIN INTACT THROUGH MONDAY MORNING.
ON MONDAY...A WEAK SURFACE RIDGE WILL BE SANDWICHED BETWEEN LOW
PRESSURE OVER THE CANADIAN MARITIMES AND A SECOND LOW THAT WILL BE
ADVANCING EAST INTO THE UPPER MIDWEST. THE SOUTHERLY FLOW THAT SETS
UP BETWEEN THESE TWO SYSTEMS WILL ALLOW TEMPERATURES TO REBOUND TO
NEAR SEASONAL LEVELS...AFTER A COLD START TO THE DAY. ANY LAKE
EFFECT SNOW SHOWERS THAT LINGER SOUTHEAST OF LAKE ONTARIO SHOULD END
BY EARLY AFTERNOON.
AS THE UPPER MIDWEST LOW TRACKS EAST ACROSS THE CENTRAL GREAT LAKES
SUNDAY NIGHT...A POTENT LOW LEVEL JET WILL BE HEADING NORTHEAST
TOWARD THE LOWER GREAT LAKES. THE LOW LEVEL JET WILL TAP INTO DEEPER
MOISTURE OVER THE LOWER OHIO AND TENNESSEE VALLEYS AND ALLOW PCPN TO
SPREAD EAST ACROSS OUR CWA. STRONG WARM AIR ADVECTION ALOFT ON THE
NOSE OF THE LOW LEVEL JET WILL CREATE A TEMPERATURE PROFILE THAT
WILL SUPPORT A WINTRY MIX OF PRECIPITATION...INCLUDING THE
POSSIBILITY OF SLEET AND FREEZING RAIN. THE LATEST GUIDANCE
SUGGESTS THAT THE CORE OF THE LOW LEVEL JET AND WARMEST TEMPERATURES
ALOFT WILL SHIFT EAST INTO CENTRAL AND EASTERN NEW YORK DURING THE
SECOND HALF OF THE NIGHT. AS A RESULT...THE RISK FOR FREEZING RAIN
MAY BE GREATER ACROSS THESE AREAS.
EXPECT TEMPERATURES TO HOLD STEADY OR SLOWLY RISE MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE CENTRAL GREAT LAKES LOW WILL SHIFT EAST ACROSS SOUTHERN ONTARIO
AND SOUTHERN QUEBEC ON TUESDAY. A PAIR OF FRONTS TRAILING SOUTH OF
THE LOW WILL HAVE SOME IMPACT ON THE CWA. MIXED PCPN AT THE START OF
THE DAY MAY CHANGE TO RAIN DURING THE MORNING...BEFORE COLDER AIR
BUILDS IN DURING THE AFTERNOON AND CHANGES THE PCPN BACK TO SNOW.
AS THE COLDER AIR DEEPENS TUESDAY NIGHT...WIDESPREAD SNOW SHOWERS
WILL CONTINUE.
AS FOR ANY WIND POTENTIAL...THERE IS A LOW LEVEL JET FORECAST TO
MOVE INTO THE REGION...NEAR 60-70KTS. GFS BUFKIT MOMENTUM TRANSFER
INDICATES A SUB-WARNING RESPONSE AS THE COLD AIR WORKS ITS WAY INTO
WESTERN NY. THIS MAKES SENSE AS THE SURFACE LOW SHOULD BE NO LONGER
DEEPENING AS IT MOVES WELL TO THE NORTH...WITH A ONLY A SMALL
ISALLOBARIC WIND RESPONSE AS THE MAIN PRESSURE CHANGES WILL BE WELL
NORTH OF THE REGION.
ONCE THIS SYSTEM MOVES OUT OF THE REGION...EXPECT SCATTERED SNOW
SHOWERS AND POSSIBLE STEADIER LAKE EFFECT SNOW TO CONTINUE INTO
WEDNESDAY.
ANOTHER RIDGE MOVES PAST ON THURSDAY FOR DRY WEATHER.
THE NEXT SYSTEM ALSO APPEARS TO BE FAIRLY WELL HANDLED BY VARIOUS
GUIDANCE PACKAGES. THIS SYSTEM CAN CURRENTLY BE FOUND HEADING
EAST...JUST SOUTH OF THE ALEUTIAN ISLANDS ON SATELLITE IMAGERY.
MODELS TAKE THIS FEATURE AND CREATE A CUTOFF OVER THE DESERT
SOUTHWEST...AND THEN ACROSS THE PLAINS AND INTO THE GREAT LAKES
REGION ON FRIDAY. CUTOFFS ARE NOT WELL HANDLED BY MODELS...AND
OFTEN SLOWER MOVE EAST THAN MODEL FORECASTS. WILL FORECAST A CHANCE
OF PRECIPITATION WITH THIS FEATURE AS IT IS SEVEN DAYS OUT...BUT IT
MIGHT END UP REMAINING DRY FOR FRIDAY.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
SCT/BKN VFR CIGS PRESENT AT 12Z ACROSS THE AREA WITH SCATTERED LIGHT
SNOW SHOWERS ACROSS WESTERN NY. A WEAK LOW PRESSURE AREA ARRIVING
FROM NEAR GEORGIAN BAY WILL CONTINUE TO BRING SCATTERED SNOW SHOWERS
ALONG WITH LIGHT AND VARIABLE WINS TROUGH MUCH OF TODAY AND INTO
TONIGHT. THE WEAK LOW WILL BE ABSORBED BY A COASTAL STORM TONIGHT
AND A MORE ALIGNED NORTHWEST FLOW WILL DEVELOP WITH ORGANIZED LAKE
SNOWS RETURNING SOUTHEAST OF THE LAKES SUNDAY MORNING.
OUTLOOK...
SUNDAY THROUGH SUNDAY NIGHT...VFR/MVFR WITH SCATTERED SNOW SHOWERS.
MONDAY...VFR.
TUESDAY...MVFR/IFR...RAIN CHANGING OVER TO SNOW LATE.
TUESDAY NIGHT THROUGH WEDNESDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT
SNOW SHOWERS.
&&
.MARINE...
A COLD FRONT WILL STALL OVER THE SOUTHERN SHORE OF LAKE ONTARIO
TODAY AS A WEAK SURFACE LOW TRACKS EAST ALONG THE BOUNDARY. THIS
WILL WILL RESULT IN WINDS WILL BECOMING LIGHT AND VARIABLE THROUGH
MUCH OF TODAY. WILL CONTINUE SCA FOR THE SOUTHERN AND SOUTHEASTERN
LAKE ONTARIO NEAR SHORES THROUGH MID MORNING WITH HIGHER WAVES
LINGERING AFTER WINDS SUBSIDE. NORTHWESTERLY WINDS WILL INCREASE
SUNDAY AS COASTAL STORM SYSTEM MOVES EAST OF NEW ENGLAND. THIS WILL
LIKELY BRING ANOTHER ROUND OF SMALL CRAFT ADVISORIES ALONG THE
SOUTHERN LAKE ONTARIO SHORELINE.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SMITH
NEAR TERM...APFFEL/SMITH
SHORT TERM...TJP
LONG TERM...TJP/ZAFF
AVIATION...SMITH
MARINE...APFFEL/SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
948 AM EST SAT FEB 16 2013
.SYNOPSIS...
A STRONG TROUGH ALOFT WILL PIVOT ACROSS THE SOUTHEASTERN US
TODAY...AND RESULT IN RAPID CYCLOGENESIS UP THE MIDDLE ATLANTIC
AND NORTHEAST COASTS TONIGHT AND SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 AM SATURDAY...
UPDATE:
REAL QUICK UPDATE TO INCLUDE EXPANSION OF WINTER WX ADVISORY FOR
MOST OF CENTRAL NC...THAT NOW EXTENDS ALONG AND EAST OF A LINE FROM
ALBEMARLE...TO ASHEBORO...TO GREENSBORO.
ANOTHER UPDATE WILL BE ISSUED SHORTLY.
ALTHOUGH IT APPEARS THAT THE SURFACE CYCLONE WILL BE DEVELOPING
CLOSER TO THE COAST (NEAR MHX) THAN PREVIOUSLY ANTICIPATED AND
THAT RELATIVELY MORE PRECIP WILL OCCUR ACROSS CENTRAL NC (PER
LATEST RAP MODEL RUNS) IN ASSOC/W STRONG LOW-LEVEL FRONTOGENESIS
12-18Z AND THEN STRONG DPVA IN THE PRESENCE OF A DESTABILIZING
AIRMASS 21-00Z...IT APPEARS THAT THE BOUNDARY LAYER WILL REMAIN
TOO WARM THROUGH ~00Z THIS EVENING FOR A CHANGEOVER TO OCCUR IN
MOST LOCATIONS...WITH THE COLDER AIRMASS CURRENTLY BUILDING INTO
THE MID-ATLANTIC STALLING NORTH OF CENTRAL NC DUE TO VERY STRONG
H5 HEIGHT FALLS IN ADVANCE OF THE APPROACHING UPPER LEVEL
TROUGH...RESULTING IN BROAD PRESSURE FALLS OVER NC/VA WHICH WILL
HOLD A WEAK PRESSURE TROUGH IN PLACE AND DELAY THE ARRIVAL OF THE
COLDER AIRMASS FROM THE NORTH. EXPECT THE BEST CHANGEOVER
POTENTIAL TO OCCUR AFTER 00Z...WHEN FORCING FOR PRECIP WILL
GENERALLY BEGIN TO WANE OVER CENTRAL NC AND PRECIPITATION WILL
BEGIN TO PROGRESS EAST TOWARD THE COAST.
BASICALLY...THIS MAY BE YET ANOTHER CASE WHERE THE COLD AIR `CHASES`
THE PRECIP...EXCEPT PERHAPS N/NE OF THE TRIANGLE WHERE FAVORABLE
THERMAL PROFILES ARE MORE LIKELY TO COINCIDE WITH STRONG FORCING IN
THE FORM OF LOW-LEVEL FRONTOGENESIS AND STRONG DPVA IN THE PRESENCE
OF VERY STEEP (7-8C/KM) MID-LEVEL LAPSE RATES. ONE CAVEAT...GIVEN
STRONG DPVA...GOOD LOW-LEVEL FRONTOGENESIS AND VERY STEEP MID-LEVEL
LAPSE RATES (7-8 C/KM) IN ADVANCE OF THE APPROACHING UPPER LEVEL
TROUGH...IT IS POSSIBLE THAT A QUICK BURST OF ACCUMULATING
CONVECTIVE SNOW COULD OCCUR AT ABOUT THE SAME TIME AS THE COLDER
AIRMASS BEGINS TO ARRIVE FROM THE NORTH ~00Z FROM GUILFORD/RANDOLPH
COUNTIES EASTWARD. HOWEVER...PREVIOUS EXPERIENCE WOULD SUGGEST THAT
TOO MUCH UNCERTAINTY IS PRESENT TO WARRANT EXPANDING THE ADVISORY
AREA WHEN WAITING FOR A COLDER AIRMASS TO ADVECT INTO THE AREA AND
WHEN RELYING PRIMARILY ON CONVECTIVE PRECIPITATION FOR
ACCUMULATIONS. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 210 AM SATURDAY...
BREEZY COLD CONDITIONS EARLY SUNDAY WILL PERSIST MUCH OF THE DAY.
LOW LEVEL THICKNESSES SUGGEST THE COLDEST AIR WILL BE OVER THE
NORTHERN AND EASTERN ZONES WHERE HIGHS WILL STRUGGLE TO REACH NEAR
40. TEMPERATURES IN THE 40S EXPECTED ACROSS THE SOUTHERN TIER NEAR
THE SC BORDER. THE COLD UPPER TROUGH IS FORECAST TO BEGIN TO LIFT
OUT LATE SUNDAY INTO MONDAY. HOWEVER... THE COLD SURFACE HIGH
PRESSURE IS FORECAST TO BE DIRECTLY OVERHEAD SUNDAY NIGHT INTO 12Z
MONDAY. THIS WILL MEAN COLD/CLEAR/CALM CONDITIONS WITH HEAVY FROST
AND HARD FREEZE BY 12Z MONDAY. LOWS 18-25. WAA WILL BEGIN MONDAY...
ESPECIALLY IN THE AFTERNOON. OTHER THAN A FEW HIGH CLOUDS... IT
SHOULD BE MOSTLY SUNNY WITH SW WINDS 10-15 MPH. HIGHS 48 TO 55 NE TO
SW.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 210 AM SATURDAY...
A COUPLE OF SYSTEMS ARE EXPECTED TO BRING RAIN CHANCES TO OUR REGION
THIS WEEK. THE FIRST IS FORECAST FOR TUESDAY. STRONG WARMING OUT
AHEAD OF THE COLD FRONT WILL LEAD TO ALL RAIN SHOWERS. A BIT OF
IN-SITU CAD MAY KEEP TEMPS DOWN IN THE PIEDMONT. QPF CONTINUES TO BE
LIGHT WITH UP TO 0.25 IN THE NW WITH LESSER AMOUNTS TO THE EAST.
CLOUDY WITH A 40-50 PERCENT CHANCE OF SHOWERS. HIGHS GENERALLY IN
THE 45-50 RANGE NW... WITH 50S SE AFTER LOWS OF 35-42 TUESDAY.
WEDNESDAY AND THURSDAY... HIGH PRESSURE SHOULD BUILD IN FROM THE NW
AND NORTH WED-THU... WITH THE STRONGEST CAA EXPECTED THU. THIS MAY
SET UP A STRONGER CAD EVENT FOR FRIDAY AS THE HIGH IS FORECAST TO BE
IN A FAVORABLE POSITION AND STRENGTH TO INDUCE CAD AS THE NEXT
SYSTEM APPROACHES FRIDAY.
WED...FAIR AND SEASONABLE. LOWS IN THE 30S. HIGHS IN THE 50S. THU...
MOSTLY SUNNY. LOWS 25-30. HIGHS 48-53. FRI..MOSTLY CLOUDY. A CHANCE
OF RAIN. CHILLY. LOWS IN THE 30S. HIGHS IN THE 40S EXCEPT 50-55 SE.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
AS OF 635 AM SATURDAY...
AFTER INITIALLY VFR CONDITIONS...THE PASSAGE OF A STRONG DEEP LAYER
FRONTAL ZONE WILL RESULT IN A RAPIDLY EXPANDING...BUT NARROW...
PRECIPITATION AXIS ACROSS THE WEST-CENTRAL CAROLINAS BETWEEN 12-15Z.
THE PRECIPITATION AXIS WILL THEN EXPAND IN AREAL EXTENT AND PIVOT
EASTWARD ACROSS CENTRAL NC THROUGH THIS EVENING...OWING TO THE
AMPLIFICATION OF A STRONG TROUGH ALOFT FROM THE CENTRAL PLAINS TO
THE SOUTHEAST STATES. THE PRECIPITATION WILL LIKELY BEGIN AS A MIX
OF RAIN AND SNOW...BEFORE GRADUALLY TRANSITIONING TO ALL SNOW FOR
THE AFTERNOON AND EVENING HOURS. CEILINGS AND VISIBILITY
RESTRICTIONS WILL CONSEQUENTLY FALL INTO MVFR-IFR RANGE...BEFORE THE
STEADY PRECIPITATION ENDS AND SKIES CLEAR FROM WEST TO EAST THIS
EVENING. A FEW LINGERING SNOW SHOWERS WILL BE POSSIBLE THROUGH
MIDNIGHT...HOWEVER...AS THE VERY COLD AND DYNAMIC TROUGH AXIS ALOFT
PIVOTS EASTWARD.
LOOKING AHEAD: BREEZY CONDITIONS SUNDAY...FOLLOWED BY ANOTHER
FRONTAL SYSTEM AND ASSOCIATED SUB-VFR CONDITIONS AND RAIN THAT WILL
AFFECT THE REGION TUE.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 4 AM EST
SUNDAY FOR NCZ011-027-028-042-043-078-088-089.
WINTER WEATHER ADVISORY UNTIL 4 AM EST SUNDAY FOR NCZ007>010-
022>026-039>041-073>077-083>086.
&&
$$
SYNOPSIS...MWS
NEAR TERM...CBL/VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...MWS/BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
635 AM EST SAT FEB 16 2013
.SYNOPSIS...
A STRONG TROUGH ALOFT WILL PIVOT ACROSS THE SOUTHEASTERN US
TODAY...AND RESULT IN RAPID CYCLOGENESIS UP THE MIDDLE ATLANTIC
AND NORTHEAST COASTS TONIGHT AND SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 340 AM SATURDAY...
...PERIOD OF WINTRY WEATHER REMAINS POSSIBLE THIS EVENING INTO
TONIGHT ALONG AND EAST OF HIGHWAY 1...
WILL LEAVE THE CURRENT ADVISORY AS-IS. EXPECT ACCUMULATIONS 1-2" AT
MOST...AND THOSE AMOUNTS ARE MOST LIKELY IN THE NE COASTAL PLAIN
NEAR THE VA BORDER N/NE OF THE TRIANGLE. ALTHOUGH IT APPEARS THAT
THE SURFACE CYCLONE WILL BE DEVELOPING CLOSER TO THE COAST (NEAR
MHX) THAN PREVIOUSLY ANTICIPATED AND THAT RELATIVELY MORE PRECIP
WILL OCCUR ACROSS CENTRAL NC (PER LATEST RAP MODEL RUNS) IN ASSOC/W
STRONG LOW-LEVEL FRONTOGENESIS 12-18Z AND THEN STRONG DPVA IN THE
PRESENCE OF A DESTABILIZING AIRMASS 21-00Z...IT APPEARS THAT THE
BOUNDARY LAYER WILL REMAIN TOO WARM THROUGH ~00Z THIS EVENING FOR A
CHANGEOVER TO OCCUR IN MOST LOCATIONS...WITH THE COLDER AIRMASS
CURRENTLY BUILDING INTO THE MID-ATLANTIC STALLING NORTH OF CENTRAL
NC DUE TO VERY STRONG H5 HEIGHT FALLS IN ADVANCE OF THE APPROACHING
UPPER LEVEL TROUGH...RESULTING IN BROAD PRESSURE FALLS OVER NC/VA
WHICH WILL HOLD A WEAK PRESSURE TROUGH IN PLACE AND DELAY THE
ARRIVAL OF THE COLDER AIRMASS FROM THE NORTH. EXPECT THE BEST
CHANGEOVER POTENTIAL TO OCCUR AFTER 00Z...WHEN FORCING FOR PRECIP
WILL GENERALLY BEGIN TO WANE OVER CENTRAL NC AND PRECIPITATION WILL
BEGIN TO PROGRESS EAST TOWARD THE COAST.
BASICALLY...THIS MAY BE YET ANOTHER CASE WHERE THE COLD AIR `CHASES`
THE PRECIP...EXCEPT PERHAPS N/NE OF THE TRIANGLE WHERE FAVORABLE
THERMAL PROFILES ARE MORE LIKELY TO COINCIDE WITH STRONG FORCING IN
THE FORM OF LOW-LEVEL FRONTOGENESIS AND STRONG DPVA IN THE PRESENCE
OF VERY STEEP (7-8C/KM) MID-LEVEL LAPSE RATES. ONE CAVEAT...GIVEN
STRONG DPVA...GOOD LOW-LEVEL FRONTOGENESIS AND VERY STEEP MID-LEVEL
LAPSE RATES (7-8 C/KM) IN ADVANCE OF THE APPROACHING UPPER LEVEL
TROUGH...IT IS POSSIBLE THAT A QUICK BURST OF ACCUMULATING
CONVECTIVE SNOW COULD OCCUR AT ABOUT THE SAME TIME AS THE COLDER
AIRMASS BEGINS TO ARRIVE FROM THE NORTH ~00Z FROM GUILFORD/RANDOLPH
COUNTIES EASTWARD. HOWEVER...PREVIOUS EXPERIENCE WOULD SUGGEST THAT
TOO MUCH UNCERTAINTY IS PRESENT TO WARRANT EXPANDING THE ADVISORY
AREA WHEN WAITING FOR A COLDER AIRMASS TO ADVECT INTO THE AREA AND
WHEN RELYING PRIMARILY ON CONVECTIVE PRECIPITATION FOR
ACCUMULATIONS. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 210 AM SATURDAY...
BREEZY COLD CONDITIONS EARLY SUNDAY WILL PERSIST MUCH OF THE DAY.
LOW LEVEL THICKNESSES SUGGEST THE COLDEST AIR WILL BE OVER THE
NORTHERN AND EASTERN ZONES WHERE HIGHS WILL STRUGGLE TO REACH NEAR
40. TEMPERATURES IN THE 40S EXPECTED ACROSS THE SOUTHERN TIER NEAR
THE SC BORDER. THE COLD UPPER TROUGH IS FORECAST TO BEGIN TO LIFT
OUT LATE SUNDAY INTO MONDAY. HOWEVER... THE COLD SURFACE HIGH
PRESSURE IS FORECAST TO BE DIRECTLY OVERHEAD SUNDAY NIGHT INTO 12Z
MONDAY. THIS WILL MEAN COLD/CLEAR/CALM CONDITIONS WITH HEAVY FROST
AND HARD FREEZE BY 12Z MONDAY. LOWS 18-25. WAA WILL BEGIN MONDAY...
ESPECIALLY IN THE AFTERNOON. OTHER THAN A FEW HIGH CLOUDS... IT
SHOULD BE MOSTLY SUNNY WITH SW WINDS 10-15 MPH. HIGHS 48 TO 55 NE TO
SW.
&&
.LONG TERM / MONDAY NIGHT THROUGH FRIDAY/...
AS OF 210 AM SATURDAY...
A COUPLE OF SYSTEMS ARE EXPECTED TO BRING RAIN CHANCES TO OUR REGION
THIS WEEK. THE FIRST IS FORECAST FOR TUESDAY. STRONG WARMING OUT
AHEAD OF THE COLD FRONT WILL LEAD TO ALL RAIN SHOWERS. A BIT OF
IN-SITU CAD MAY KEEP TEMPS DOWN IN THE PIEDMONT. QPF CONTINUES TO BE
LIGHT WITH UP TO 0.25 IN THE NW WITH LESSER AMOUNTS TO THE EAST.
CLOUDY WITH A 40-50 PERCENT CHANCE OF SHOWERS. HIGHS GENERALLY IN
THE 45-50 RANGE NW... WITH 50S SE AFTER LOWS OF 35-42 TUESDAY.
WEDNESDAY AND THURSDAY... HIGH PRESSURE SHOULD BUILD IN FROM THE NW
AND NORTH WED-THU... WITH THE STRONGEST CAA EXPECTED THU. THIS MAY
SET UP A STRONGER CAD EVENT FOR FRIDAY AS THE HIGH IS FORECAST TO BE
IN A FAVORABLE POSITION AND STRENGTH TO INDUCE CAD AS THE NEXT
SYSTEM APPROACHES FRIDAY.
WED...FAIR AND SEASONABLE. LOWS IN THE 30S. HIGHS IN THE 50S. THU...
MOSTLY SUNNY. LOWS 25-30. HIGHS 48-53. FRI..MOSTLY CLOUDY. A CHANCE
OF RAIN. CHILLY. LOWS IN THE 30S. HIGHS IN THE 40S EXCEPT 50-55 SE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 635 AM SATURDAY...
AFTER INITIALLY VFR CONDITIONS...THE PASSAGE OF A STRONG DEEP LAYER
FRONTAL ZONE WILL RESULT IN A RAPIDLY EXPANDING...BUT NARROW...
PRECIPITATION AXIS ACROSS THE WEST-CENTRAL CAROLINAS BETWEEN 12-15Z.
THE PRECIPITATION AXIS WILL THEN EXPAND IN AREAL EXTENT AND PIVOT
EASTWARD ACROSS CENTRAL NC THROUGH THIS EVENING...OWING TO THE
AMPLIFICATION OF A STRONG TROUGH ALOFT FROM THE CENTRAL PLAINS TO
THE SOUTHEAST STATES. THE PRECIPITATION WILL LIKELY BEGIN AS A MIX
OF RAIN AND SNOW...BEFORE GRADUALLY TRANSITIONING TO ALL SNOW FOR
THE AFTERNOON AND EVENING HOURS. CEILINGS AND VISIBILITY
RESTRICTIONS WILL CONSEQUENTLY FALL INTO MVFR-IFR RANGE...BEFORE THE
STEADY PRECIPITATION ENDS AND SKIES CLEAR FROM WEST TO EAST THIS
EVENING. A FEW LINGERING SNOW SHOWERS WILL BE POSSIBLE THROUGH
MIDNIGHT...HOWEVER...AS THE VERY COLD AND DYNAMIC TROUGH AXIS ALOFT
PIVOTS EASTWARD.
LOOKING AHEAD: BREEZY CONDITIONS SUNDAY...FOLLOWED BY ANOTHER
FRONTAL SYSTEM AND ASSOCIATED SUB-VFR CONDITIONS AND RAIN THAT WILL
AFFECT THE REGION TUE.
&&
RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 PM SATURDAY TO 4 AM EST SUNDAY FOR
NCZ007>011-025>028-041>043-077-078-085-086-088-089.
&&
$$
SYNOPSIS...MWS
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...MWS/PWB
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
655 AM EST SAT FEB 16 2013
.SYNOPSIS...
A MOIST UPPER LEVEL LOW WILL CROSS THE REGION TODAY...WITH DRY HIGH
PRESSURE BUILDING IN FROM THE NORTH SUNDAY. A COLD FRONT WILL
APPROACH THE CAROLINAS AND NORTHEAST GEORGIA TUESDAY WITH ANOTHER
AREA OF CANADIAN HIGH PRESSURE BUILDING IN ON WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF EARLY SAT MORNING...UPPER TROUGH WILL SWING THROUGH THE REGION
TODAY WITH FURTHER COLD ADVECTION AND STRONG VORT MAX ACCOMPANYING
IT. VERY LIGHT PRECIP ALREADY FALLING OVER THE PIEDMONT. THIS AREA
IS FAVORED BY THE NAM...GFS...RAP AND HRRR AS BEING THE FOCUS FOR
THE BULK OF THE PRECIP. FORCING FROM THE WAVE WILL BE ENHANCED OVER
THE PIEDMONT BY LOW LEVEL CONVERGENCE BETWEEN THE INVADING ARCTIC
AIRMASS AND EXISTING COASTAL AIR. THE TROUGH STEADILY PROGRESSES
EAST...WITH THE BASE HAVING DEPARTED THE CWFA BY 00Z...WITH DEEP DRY
AIR RAPIDLY WORKING IN.
TEMPERATURE PROFILES DO NOT INDICATE A WARM NOSE GIVEN THE ALREADY
COLD AIR IN PLACE. DEEP SATURATION MEANS RAIN OR SNOW WILL MAINLY BE
DETERMINED BY SURFACE TEMP. FREEZING LEVELS ARE PRETTY LOW AND SFC
TEMPS WILL BE MOSTLY IN THE 30S OVER THE PIEDMONT. A RAIN/SNOW MIX
WILL LIKELY TRANSITION TO SNOW AS THE FREEZING LEVEL LOWERS DUE TO
THE WET BULB EFFECT. FOR QPF...SOMEWHAT TRICKY WITH OPERATIONAL
MODELS SHOWING SOME POSSIBLE CONVECTIVE EFFECTS AND LOCALIZED AREAS
SEEING SIGNIFICANTLY HIGHER AMOUNTS OF SNOWFALL. INDEED BOTH THE NAM
AND GFS SHOW UP TO A COUPLE HUNDRED JOULES OF MUCAPE THIS AFTERNOON
OVER A PORTION OF NE GA AND THE WESTERN UPSTATE. 21Z SREF BACKS THIS
UP WITH LIKELY-RANGE PROBS OF 100 J. SO THIS COULD HELP ENHANCE
TOTALS DURING THE EARLY TO MID AFTERNOON WHEN THE FORCING IS
STRONGEST ANYWAY. CHOSE MODEST QPF DERIVED FROM A MODEL BLEND WHICH
HAPPENS TO BE IN LINE WITH THE GENERAL PATTERN AND AMOUNTS OF THE
LAST FEW GFS RUNS...WITH ABOUT A QUARTER INCH SOUTHEAST OF A LINE
FROM GREENWOOD TO CHESTER. FAIRLY HIGH SNOW RATIOS OF 13-16 TO 1
WILL PRODUCE TOTALS GENERALLY OF 1 TO 2 INCHES TODAY. THIS MEETS OUR
WINTER WX ADVY CRITERIA OVER THE SRN FOOTHILLS AND PIEDMONT OF NC AS
WELL AS MOST OF THE SC PIEDMONT.
IN ADDITION TO THE SYNOPTIC FORCING...PERSISTENT NORTHWEST FLOW WILL
PRODUCE ENHANCED SNOWFALL IN THE UPSLOPE AREAS OF THE MOUNTAINS.
NONETHELESS...TOTALS ARE COMPARABLE TO PREVIOUS FCST AND EXISTING
WINTER WX ADVY WILL COVER THIS.
HIGH TEMPS TODAY WILL BE WELL BELOW NORMAL IN THE ARCTIC AIR. WITH
MOSTLY OVERCAST SKIES USED A BLEND OF GFS AND CMC-REGIONAL TEMPS.
BOTH THE GFS AND NAM QUICKLY DRY THINGS OUT BEHIND THE DEPARTING
TROUGH SO SOME BREAKS IN THE CLOUD COVER COULD COME LATE IN THE DAY
ESPECIALLY SOUTHWEST...BUT PROBABLY TOO LATE TO HAVE MUCH OF AN
IMPACT ON HIGHS. FURTHERMORE ANY SNOW COVER COULD LIMIT TEMPS FROM
RISING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
AS OF 300 AM SATURDAY...THE UPPER TROUGH AXIS WILL PROGRESS QUICKLY
ACROSS THE REGION TONIGHT...BRINGING A QUICK END TO ANY LINGERING
PRECIP. THE ONLY EXCEPTION WILL BE ACROSS THE FAR WESTERN NC MTNS...
AS A MOIST NW FLOW SHOULD YIELD PERSISTENT SNOW SHOWERS THROUGH THE
OVERNIGHT. THE MODELS ARE RATHER STINGY WITH QPF TONIGHT...AS THE
NAM BARELY SQUEEZES OUT .05-.1 INCH ALONG THE TENN BORDER...WHILE
THE GFS IS EVEN DRIER. THIS IS SOMEWHAT SURPRISING...AS THE MOIST
LAYER IS PROGGED TO EXTEND TO ABOUT 800 MB THROUGH THE OVERNIGHT...
WHILE H8 WINDS SHOULD BE IN THE 30-40 KT RANGE. IN ADDITION...TEMPS
IN THE MOIST LAYER ARE EXPECTED TO BE EXTREMELY COOL...AS LOW AS -19
C BY 12Z SUNDAY. THEREFORE...EVEN IF THERE IS LITTLE LIQUID
EQUIVALENT...THIS PATTERN IS SUGGESTIVE OF EFFICIENT SNOW
PRODUCTION...WITH SNOW:LIQUID RATIOS AS HIGH AS 30:1 POSSIBLE LATE
TONIGHT. THEREFORE...WE WILL FORECAST AN ADDITIONAL 1 TO 4 INCHES IN
THE USUAL NW FLOW AREAS OVERNIGHT.
TEMPS WILL BE VERY COOL TONIGHT THROUGH TOMORROW...EASILY 10 DEGREES
BELOW CLIMO. HOWEVER...WITH HEIGHTS RISING IN THE WAKE OF THE UPPER
TROUGH AXIS...THE REMAINDER OF THE SHORT TERM WILL FEATURE QUICKLY
MODERATING TEMPS THAT WILL WARM VERY CLOSE TO NORMAL BY MONDAY
AFTERNOON.
BY THE END OF THE PERIOD...A MAJOR STORM SYSTEM WILL LIFT OUT OF THE
CENTRAL PLAINS...WITH AN ATTENDANT FRONTAL BAND OF PRECIP EXPECTED
TO MARCH ACROSS THE TENN VALLEY LATE MONDAY/MONDAY NIGHT. POPS WILL
INCREASE QUICKLY FROM WEST TO EAST ACROSS OUR AREA LATE MONDAY
NIGHT...BECOMING LIKELY ACROSS THE NC MTNS BY DAYBREAK. IT STILL
APPEARS THAT PRECIP COULD BEGIN AS SNOW IN THE HIGH ELEVATIONS OF
THE NC MTNS. THERE COULD ALSO BE SOME BRIEF FREEZING RAIN IN
SHELTERED VALLEYS TUE MORNING...BUT THE PREDOMINANT P-TYPE SHOULD BE
RAIN IN ALL AREAS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 AM SATURDAY...THE COLD FRONT WILL STILL BE OFF TO THE WEST
BY 12Z TUE WITH A DECENT SPREAD OF LIGHT PRECIP ACROSS MOST OF THE
CWFA...INCREASING EAST THROUGHOUT THE DAY. THE STRONGEST QG FORCING
WILL REMAIN NORTH DURING FROPA...HOWEVER A 100 KT FINGER OF THE STJ
WILL PUSH INTO MIDLANDS AND PROVIDE SOME MEASURE OF UPPER DIV
SUPPORT OVER THE SRN MOST ZONES. THE FLOW BACKS DOWN THE PROFILE AND
THE LLVL JET BECOMES ALIGNED PARALLEL TO THE BLUE RIDGE...THUS
MECHANICAL LIFT WILL BE LIMITED. ALL THIS TO SAY THE ADDITIONAL
PRECIP AMOUNTS UNTIL FROPA EARLY WED WILL BE RATHER LIGHT WITH MOST
AREAS RECEIVING LESS THAN A QUARTER INCH. THERE COULD BE SOME WRAP
AROUND -SNSH LINGERING ACROSS THE NRN MTNS THROUGH 06Z WED...BUT THE
TREND HAS BEEN FOR LESS AND LESS AVAILABLE MOISTURE...ESP WITH THE
ECMWF. IN ANY CASE...ANY AMOUNTS OF SNOW WILL BE LIGHT BTW 00Z-06Z
WED. HIGH TEMPS WILL BE TRICKY WITH ALL THE CLOUDS/PRECIP...YET
DECENT SW/LY FLOW...BUT MAXES A CAT OR SO BELOW NORMAL SEEMS
REASONABLE PER THE LLVL THICKNESS PATTERN AND SUFFICIENT LACK OF
INSOL.
THE MODELS AGREE WELL WITH THE PATTERN WED THROUGH THE END OF THE
PERIOD. A SHARP RIDGE AXIS WILL BUILD ACROSS THE PLAINS STATES AND
PROPAGATE TOWARD THE EAST COAST THROUGH 00Z FRI. THIS WILL MAINTAIN
CANADIAN HIGH PRESSURE AT THE SFC AND LOW BL THETA/E AIR WED AND
THU. GOOD INSOL...BUT N/LY FLOW WILL KEEP MAXES NEAR NORMAL
PERHAPS A DEGREE OR SO BELOW WED. A MODIFYING AIRMASS WITH
INCREASING MID/HIGH CLOUDS THU SHOULD HOLD MAX TEMPS IN CHECK AT
ABOUT 3-4 DEGREES BELOW NORMAL.
ANOTHER LOW PRESSURE SYSTEM DEEPENS AND MOVES INTO THE CENTRAL
MIDWEST BY THU EVENING. THE BEST UPPER DYNAMICS AGAIN WILL BE WELL
NORTH OF THE CWFA BY THE TIME A COLD FRONT REACHES THE NC MTNS
AROUND MID DAY FRI. THE MAIN PRECIP TYPE LOOKS TO BE ALL RAIN...WITH
SOME HIGH ELEV SNOW. AGAIN...AMOUNTS LOOK TO REMAIN ON THE LOW SIDE.
THERE COULD BE A DEVELOPING TRIPLE POINT LOW AND A MEASURE OF
SFC/BASED SHEAR STORM DEVELOPMENT FRI AFTERNOON...BUT INSTABILITY BE
A LIMITING FACTOR FOR ANY REAL STRONG/SVR CONCERN OR CONJECTURE AT
THIS POINT. THE CWFA WILL LIKELY SEE A NOTICEABLE GRADIENT OF MAX
TEMPS FRI AS THE LLVL THERMAL TROF EXITS TO THE NORTH AND A WARM
FRONT IMPINGES UPON THE AREA FROM THE SOUTH. FOR NOW...GENERALLY
THINK MAX TEMPS WILL BE A 3-5 DEGREES ABOVE NORMAL SOUTH AND ABOUT
5-8 DEGREES BELOW NORMAL NORTH OF I40.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...LOWERING CIG LIKELY THROUGH THE MORNING. LIGHT SHOWERS
JUST BEFORE DAYBREAK HAVE BROUGHT AT LEAST BRIEF PERIODS OF MVFR
CIGS TO SITES THEY PASS OVER. KCLT HAS ALREADY DONE SO ONCE AND
SHOULD SEE THIS INCREASINGLY FREQUENTLY AS PRECIP BECOMES MORE
WIDESPREAD...BUT AN EVENTUAL SOLID MVFR DECK WILL DEVELOP. MIDDAY
PEAK IN PRECIP ACTIVITY EXPECTED AHEAD OF UPPER TROUGH PASSAGE.
PRECIP WILL BEGIN AS A RAIN/SNOW MIX BUT A GRADUAL CHANGEOVER TO ALL
SNOW SHOULD OCCUR...PROBABLY BY LATE MORNING. SHORT TERM GUIDANCE
PRODUCES MVFR VSBY IN MOST AREAS AFFECTED BY PRECIP...SO TIED VSBY
FCST TO PRECIP. CIGS LIFT TO VFR BY AFTERNOON THEN SCATTER AFTER 00Z
SUN. NW WINDS THRU THE PERIOD. BIGGEST GUST POTENTIAL IS THIS
EVENING AS ARCTIC AIR BLASTS IN PROMOTING MIXING.
ELSEWHERE...CIGS WILL LOWER WITH INCREASING DEEP MOISTURE BY MID
MORNING. INITIAL -SHRA/-SHSN WILL BRING IN AT LEAST BRIEF MVFR CIGS
PRIOR TO THE WIDESPREAD LOWERING. MVFR CIGS WILL ACCOMPANY PRECIP IN
THE LATE MORNING WEST TO MIDDAY EAST. RA/SN MIX WILL TRANSITION TO
ALL SNOW FAIRLY QUICKLY AS FREEZING LEVELS ARE ALREADY LOW AND
COLDER ARCTIC AIR WORKING IN WILL FURTHER LOWER THEM. HIGH
CONFIDENCE IN AT LEAST SCATTERED PRECIP SO INCLUDED AT ALL SITES
THROUGH THE AFTN. RETURN TO VFR BY LATE AFTN WITH GUSTS POSSIBLE
FROM MIDDAY THROUGH THE END OF THE PERIOD AS COLD ADVECTION
MAINTAINS DEEPLY MIXED SFC LAYER. NO FOG EXPECTED TONIGHT WITH THE
INCOMING DRY ARCTIC AIR MASS...BUT CONTINUING UPSLOPE EFFECTS COULD
PRODUCE -SHSN AND A VFR CIG IN THE MOUNTAINS NEAR THE TN BORDER.
OUTLOOK...CONDITIONS WILL GENERALLY REMAIN DRY WITH VFR CONDITIONS
SUNDAY. HIGH PRESSURE BUILDS OVER THE REGION EARLY NEXT WEEK.
CONFIDENCE TABLE...
12-18Z 18-24Z 00-06Z 06-12Z
KCLT HIGH 81% MED 65% HIGH 100% HIGH 100%
KGSP MED 61% LOW 50% HIGH 100% HIGH 100%
KAVL HIGH 83% MED 72% HIGH 100% HIGH 100%
KHKY MED 74% MED 71% HIGH 100% HIGH 100%
KGMU MED 62% LOW 51% HIGH 100% HIGH 100%
KAND MED 62% MED 70% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.FIRE WEATHER...
DRY AND BREEZY TO WINDY CONDITIONS ARE EXPECTED ON SUNDAY.
HOWEVER...THE LOWEST RH VALUES WILL BE MID TO LATE AFTERNOON...WHILE
THE WINDIEST CONDITIONS SHOULD BE IN THE MORNING THROUGH EARLY
AFTERNOON. IN ADDITION...WE WILL HAVE TO WAIT AND SEE HOW MUCH
PRECIPITATION FALLS OVER THE NEXT 24 TO 36 HOURS IN ORDER TO ASSESS
FUEL MOISTURE CONTENT AND ASSOCIATED FIRE DANGER FOR LATE THIS
WEEKEND.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ033-
048>052-058.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NCZ053-
065-068>072-082-501-503-505-507>510.
SC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR SCZ002-
003-005>009-012>014.
&&
$$
SYNOPSIS...SBK
NEAR TERM...WIMBERLEY
SHORT TERM...JDL
LONG TERM...SBK
AVIATION...WIMBERLEY
FIRE WEATHER...HG
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1129 AM CST SAT FEB 16 2013
.DISCUSSION...
ISSUED 1001 AM CST SAT FEB 16 2013
DEEP UPPER LOW CENTERED OVER THE GREAT LAKES CONTINUES TO BE THE
PREDOMINANT WEATHER-MAKER ACROSS CENTRAL ILLINOIS TODAY. VERY COLD
AIR ALOFT ASSOCIATED WITH THIS FEATURE...WITH 12Z 500MB TEMP OF -40C
AT KILX. DESPITE PRESENCE OF SURFACE HIGH PRESSURE...STEEP LAPSE
RATES WILL LEAD TO THE DEVELOPMENT OF SCT-BKN CU ACROSS NORTH-CENTRAL
ILLINOIS THIS AFTERNOON. 13Z HRRR EVEN HINTS AT SOME CONVECTIVE
SNOW-SHOWERS ALONG/NORTH OF I-74 AFTER 20Z. LATEST VISIBLE SATELLITE
IMAGERY IS ALREADY SHOWING CU BEGINNING TO DEVELOP...AND UPSTREAM
OBS SHOW AN AREA OF LIGHT SNOW ACROSS NORTHEAST IOWA. HAVE UPDATED
THE FORECAST TO GO WITH SUNNY SKIES THIS MORNING...FOLLOWED BY
PARTLY SUNNY CONDITIONS IN THE AFTERNOON. HAVE ALSO MENTIONED
SCATTERED FLURRIES ALONG/NORTH OF I-74. ZONE UPDATE HAS ALREADY
BEEN ISSUED.
BARNES
&&
.AVIATION...
ISSUED 1129 AM CST SAT FEB 16 2013
MOSTLY CLEAR SKIES PREVAIL ACROSS CENTRAL ILLINOIS LATE THIS
MORNING...HOWEVER CU-FIELD IS RAPIDLY DEVELOPING ALONG AND NORTH
OF I-74. DUE TO VERY COLD AIR ALOFT AND RESULTING STEEP LAPSE
RATES...EXPECT CU TO BECOME SCT-BKN AT TIMES. HAVE THEREFORE
INCLUDED A TEMPO GROUP FOR LOW VFR CEILINGS AT THE I-74 TERMINALS
THIS AFTERNOON. FURTHER SOUTHWEST...MOSTLY CLEAR SKIES WILL
PERSIST AT BOTH KSPI AND KDEC. DIURNAL CLOUD COVER WILL DISSIPATE
BY SUNSET...FOLLOWED BY MOSTLY CLEAR SKIES OVERNIGHT. HIGH CLOUDS
CURRENTLY OVER THE PLAINS WILL PUSH EASTWARD SUNDAY MORNING...AS
WARM FRONT APPROACHES FROM THE WEST. WINDS WILL INITIALLY BE FROM
THE NORTHWEST AT AROUND 10KT THIS AFTERNOON...THEN WILL BECOME
LIGHT/VARIABLE TONIGHT AS HIGH PRESSURE DRIFTS ACROSS THE AREA.
ONCE THE HIGH MOVES FURTHER EAST...SOUTHEAST WINDS WILL DEVELOP ON
SUNDAY.
BARNES
&&
.PREV DISCUSSION...
ISSUED 330 AM CST SAT FEB 16 2013
FAIRLY QUIET WEATHER EXPECTED THIS WEEKEND AS BELOW NORMAL TEMPS
THROUGH TONIGHT...MODERATE BACK ABOVE NORMAL EARLY NEXT WEEK. MORE
ACTIVE WEATHER PATTERN EXPECTED DURING THE UPCOMING WORK WEEK WITH
TWO FAIRLY STRONG WEATHER SYSTEMS TO IMPACT THE REGION MON AND MON
NIGHT AND THU AND THU NIGHT. 00Z MODELS ARE IN GOOD AGREEMENT
THROUGH EARLY NEXT WEEK WITH 1ST WEATHER SYSTEM AND THEN DIVERGE
WITH HANDLING 2ND WEATHER SYSTEM LATER NEXT WORK WEEK AND WILL
STAY CLOSE TO HPC/NCEP GUIDANCE. MODELS OVERALL HAVE TRENDED A BIT
SLOWER WITH BOTH WX SYSTEMS AND STEERED THE FORECAST IN THAT
DIRECTION WITH LOWER POPS BOTH MONDAY MORNING AND THU MORNING
ESPECIALLY NE AREAS. STILL LOOKS LIKE MAINLY RAIN MONDAY AND
MONDAY NIGHT WHILE MORE SNOW OR A MIXTURE OF PRECIPITATION THU AND
THU NIGHT WITH ACCUMULATIONS POSSIBLE THEN.
SHORT TERM...TODAY THROUGH MONDAY NIGHT
STRONG UPPER LEVEL TROF REMAINS OVER EASTERN NORTH AMERICA EAST OF
THE ROCKIES TODAY AND WILL SHIFT EAST OF IL LATER TONIGHT AND SUNDAY.
AN EMBEDDED SHORT WAVE OVER NEBRASKA WILL TRACK SW OF IL TODAY
KEEPING THE BRUNT OF ITS CLOUDS SW OF CENTRAL IL TODAY. OVERALL A
PARTLY TO MOSTLY SUNNY DAY WITH MORE CLOUDS NE HALF. TEMPS ABOUT
10F BELOW NORMAL TODAY WITH UPPER 20S NE AND LOWER 30S SW. NW
WINDS 10 TO 15 MPH AND GUSTS UP TO 20 MPH AGAIN TODAY. MOSTLY
CLEAR SKIES TONIGHT AND LIGHTER WINDS AS HIGH PRESSURE RIDGE OVER
THE CENTRAL PLAINS MOVES INTO IL BY DAWN SUNDAY. COLD LOWS OF 15
TO 20F EXPECTED TONIGHT AND COLDEST NE AREAS. TEMPS MODERATE
SUNDAY AS HIGH PRESSURE RIDGE DRIFTS EAST ACROSS THE OH/TN VALLEYS
WITH RETURN SE FLOW INTO IL AND MOSTLY SUNNY SKIES. HIGHS IN THE
UPPER 30S NE AND LOWER 40S SW. BREEZY SOUTHERLY WINDS BY MONDAY
AND BUMPED UP HIGHS A FEW MORE DEGREES IN THE UPPER 40S AND LOWER
50S. STRONG LOW PRESSURE MOVES INTO THE UPPER MS VALLEY MONDAY AND
SWINGS COLD FRONT EAST THRU IL MONDAY NIGHT. THIS TO LIKELY
DEVELOP SHOWERS BY MONDAY AFTERNOON AND MON EVENING AND THEN
DIMINISH OVERNIGHT MONDAY NIGHT. BETWEEN A QUARTER AND HALF INCH
OF RAIN OVER CENTRAL IL AND LOCALLY HIGHER AMOUNTS IN SE IL WHERE
ISOLATED THUNDERSTORMS POSSIBLE SOUTH OF CHARLESTON/MATTOON MONDAY
AFTERNOON AND MON EVENING. HAVE CHANCE OF LIGHT SNOW OVERNIGHT
MONDAY NIGHT AS PRECIPITATION DIMINISHES BUT LITTLE OR NO
ACCUMULATIONS.
LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
QUIET WEATHER RETURNS TUE AND WED ALONG WITH COLDER TEMPS AND
COLDEST ON WED AS CANADIAN HIGH PRESSURE RIDGES INTO IL WED. THEN
ANOTHER LOW PRESSURE EJECTS NE INTO THE MS VALLEY BY THU NIGHT
RETURNING MORE PRECIPITATION DEVELOPING DURING THE DAY THU FROM SW
TO NE AND CONTINUE THU NIGHT. APPEARS COLD ENOUGH FOR SNOW THU
MORNING THEN MIX OF FREEZING RAIN...SLEET AND RAIN TOO SOUTHERN
AREAS THU AFTERNOON. THIS TO TRANSITION BACK TO SNOW FROM NW TO SE
DURING THU NIGHT AS COLDER AIR RETURNS. COULD BE SOME SNOW
ACCUMULATIONS THU AND THU NIGHT ESPECIALLY NORTH OF I-70 WITH
HEAVIEST AMOUNTS NORTH OF I-72. MODELS STILL NOT IN BEST AGREEMENT
WITH TRACK OF STORM SYSTEM AND OVERALL MODELS HAVE TRENDED FURTHER
NORTH WITH TRACK OF SURFACE LOW NEAR CENTRAL IL LATER THU NIGHT.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1001 AM CST SAT FEB 16 2013
.DISCUSSION...
ISSUED 1001 AM CST SAT FEB 16 2013
DEEP UPPER LOW CENTERED OVER THE GREAT LAKES CONTINUES TO BE THE
PREDOMINANT WEATHER-MAKER ACROSS CENTRAL ILLINOIS TODAY. VERY COLD
AIR ALOFT ASSOCIATED WITH THIS FEATURE...WITH 12Z 500MB TEMP OF -40C
AT KILX. DESPITE PRESENCE OF SURFACE HIGH PRESSURE...STEEP LAPSE
RATES WILL LEAD TO THE DEVELOPMENT OF SCT-BKN CU ACROSS NORTH-CENTRAL
ILLINOIS THIS AFTERNOON. 13Z HRRR EVEN HINTS AT SOME CONVECTIVE
SNOW-SHOWERS ALONG/NORTH OF I-74 AFTER 20Z. LATEST VISIBLE SATELLITE
IMAGERY IS ALREADY SHOWING CU BEGINNING TO DEVELOP...AND UPSTREAM
OBS SHOW AN AREA OF LIGHT SNOW ACROSS NORTHEAST IOWA. HAVE UPDATED
THE FORECAST TO GO WITH SUNNY SKIES THIS MORNING...FOLLOWED BY
PARTLY SUNNY CONDITIONS IN THE AFTERNOON. HAVE ALSO MENTIONED
SCATTERED FLURRIES ALONG/NORTH OF I-74. ZONE UPDATE HAS ALREADY
BEEN ISSUED.
BARNES
&&
.AVIATION...
ISSUED 506 AM CST SAT FEB 16 2013
LITTLE CHANGE NEEDED TO PREVIOUS TAF SET. HAVE BEEN SEEING A FEW
PATCHES OF CLOUDS AROUND 2500 FEET DRIFT SOUTHWARD OVER THE LAST
FEW HOURS...AND THESE WILL LINGER FOR ANOTHER HOUR OR TWO. STEADY
NORTHWEST WINDS AROUND 10 KNOTS TODAY WILL BECOME A BIT MORE
LIGHT AND VARIABLE THIS EVENING...AS AN AXIS OF HIGH PRESSURE
DRIFTS OVERHEAD.
GEELHART
&&
.PREV DISCUSSION...
ISSUED 330 AM CST SAT FEB 16 2013
FAIRLY QUIET WEATHER EXPECTED THIS WEEKEND AS BELOW NORMAL TEMPS
THROUGH TONIGHT...MODERATE BACK ABOVE NORMAL EARLY NEXT WEEK. MORE
ACTIVE WEATHER PATTERN EXPECTED DURING THE UPCOMING WORK WEEK WITH
TWO FAIRLY STRONG WEATHER SYSTEMS TO IMPACT THE REGION MON AND MON
NIGHT AND THU AND THU NIGHT. 00Z MODELS ARE IN GOOD AGREEMENT
THROUGH EARLY NEXT WEEK WITH 1ST WEATHER SYSTEM AND THEN DIVERGE
WITH HANDLING 2ND WEATHER SYSTEM LATER NEXT WORK WEEK AND WILL
STAY CLOSE TO HPC/NCEP GUIDANCE. MODELS OVERALL HAVE TRENDED A BIT
SLOWER WITH BOTH WX SYSTEMS AND STEERED THE FORECAST IN THAT
DIRECTION WITH LOWER POPS BOTH MONDAY MORNING AND THU MORNING
ESPECIALLY NE AREAS. STILL LOOKS LIKE MAINLY RAIN MONDAY AND
MONDAY NIGHT WHILE MORE SNOW OR A MIXTURE OF PRECIPITATION THU AND
THU NIGHT WITH ACCUMULATIONS POSSIBLE THEN.
SHORT TERM...TODAY THROUGH MONDAY NIGHT
STRONG UPPER LEVEL TROF REMAINS OVER EASTERN NORTH AMERICA EAST OF
THE ROCKIES TODAY AND WILL SHIFT EAST OF IL LATER TONIGHT AND SUNDAY.
AN EMBEDDED SHORT WAVE OVER NEBRASKA WILL TRACK SW OF IL TODAY
KEEPING THE BRUNT OF ITS CLOUDS SW OF CENTRAL IL TODAY. OVERALL A
PARTLY TO MOSTLY SUNNY DAY WITH MORE CLOUDS NE HALF. TEMPS ABOUT
10F BELOW NORMAL TODAY WITH UPPER 20S NE AND LOWER 30S SW. NW
WINDS 10 TO 15 MPH AND GUSTS UP TO 20 MPH AGAIN TODAY. MOSTLY
CLEAR SKIES TONIGHT AND LIGHTER WINDS AS HIGH PRESSURE RIDGE OVER
THE CENTRAL PLAINS MOVES INTO IL BY DAWN SUNDAY. COLD LOWS OF 15
TO 20F EXPECTED TONIGHT AND COLDEST NE AREAS. TEMPS MODERATE
SUNDAY AS HIGH PRESSURE RIDGE DRIFTS EAST ACROSS THE OH/TN VALLEYS
WITH RETURN SE FLOW INTO IL AND MOSTLY SUNNY SKIES. HIGHS IN THE
UPPER 30S NE AND LOWER 40S SW. BREEZY SOUTHERLY WINDS BY MONDAY
AND BUMPED UP HIGHS A FEW MORE DEGREES IN THE UPPER 40S AND LOWER
50S. STRONG LOW PRESSURE MOVES INTO THE UPPER MS VALLEY MONDAY AND
SWINGS COLD FRONT EAST THRU IL MONDAY NIGHT. THIS TO LIKELY
DEVELOP SHOWERS BY MONDAY AFTERNOON AND MON EVENING AND THEN
DIMINISH OVERNIGHT MONDAY NIGHT. BETWEEN A QUARTER AND HALF INCH
OF RAIN OVER CENTRAL IL AND LOCALLY HIGHER AMOUNTS IN SE IL WHERE
ISOLATED THUNDERSTORMS POSSIBLE SOUTH OF CHARLESTON/MATTOON MONDAY
AFTERNOON AND MON EVENING. HAVE CHANCE OF LIGHT SNOW OVERNIGHT
MONDAY NIGHT AS PRECIPITATION DIMINISHES BUT LITTLE OR NO
ACCUMULATIONS.
LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
QUIET WEATHER RETURNS TUE AND WED ALONG WITH COLDER TEMPS AND
COLDEST ON WED AS CANADIAN HIGH PRESSURE RIDGES INTO IL WED. THEN
ANOTHER LOW PRESSURE EJECTS NE INTO THE MS VALLEY BY THU NIGHT
RETURNING MORE PRECIPITATION DEVELOPING DURING THE DAY THU FROM SW
TO NE AND CONTINUE THU NIGHT. APPEARS COLD ENOUGH FOR SNOW THU
MORNING THEN MIX OF FREEZING RAIN...SLEET AND RAIN TOO SOUTHERN
AREAS THU AFTERNOON. THIS TO TRANSITION BACK TO SNOW FROM NW TO SE
DURING THU NIGHT AS COLDER AIR RETURNS. COULD BE SOME SNOW
ACCUMULATIONS THU AND THU NIGHT ESPECIALLY NORTH OF I-70 WITH
HEAVIEST AMOUNTS NORTH OF I-72. MODELS STILL NOT IN BEST AGREEMENT
WITH TRACK OF STORM SYSTEM AND OVERALL MODELS HAVE TRENDED FURTHER
NORTH WITH TRACK OF SURFACE LOW NEAR CENTRAL IL LATER THU NIGHT.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
214 PM EST SAT FEB 16 2013
.AVIATION...
VARIABLE CONTS THIS AFTN WITHIN MOIST AND UNSTABLE BNDRY LYR AND
EVIDENT IN OBSVD CONDS IN HEAVY SNOW SHSN AND IN RECENT KFWA METAR. XPC
DIURNALLY ENHANCED ACTIVITY INLAND TO DECAY OUT BY LT AFTN W/LOSS OF
HEATING. HWVR INTENSIFYING SHORE PARALLEL SINGLE BAND W/LK SUP
CONNECTION SEEN TAKING SHAPE WEST OF MANISTEE DOWN TO LUNDINGTON AND
POISED TO MARCH SWD THIS EVENING. IMPACTS AT KSBN APPEAR TO BE BRIEF
AS BAND PIVOTS WWD TO WEST OF TERMINAL BUT GOING TO BE CLOSE.
REGARDLESS A PD OF LIFR CONDS IN HEAVY SHSN LIKELY FOR A TIME THIS
EVENING AND WILL AWAIT SWD EVOLUTION OF THIS BAND BFR ATTEMPTING TO
TIME IT IN TAF. OTRWS CONDS IMPRVG ON SUN W/RTN OF VFR CONDS.
&&
.UPDATE...
WK BUT DISTINCT MESOLOW WHICH SPUN UP INVOF OF PARENT SFC TROUGH NR
KMKG ARND 0930Z CONTS TO CURL ESE THIS MORNING AND CURRENTLY WEST OF
KBTL. UPSTREAM CVRG BAND WHILE NOT AS INTENSE AS EARLIER XPCD TO
REINTENSIFY THROUGH LT MORNING ALG A KBIV...KAZO...KOEB LINE AS LK
AGGREGATE THERMAL TROUGHING STRENGTHENS AND UPSTREAM LK MSTR FLUX
MAXIMIZES INLAND. THIS MAY NECESSITATE A EWD EXPANSION OF CURRENT
ADVISORY OVR ST JOE MI TO INCLUDE BRANCH AND PERHAPS EVEN HILLSDALE.
TRENDING NR TERM RUC SOLUTIONS ADVERTISE A SIMILAR EVOLUTION AND
EVEN DIP FOCUSED BAND DOWN TO KTOL BY LT AFTN. HWVR GIVEN THINGS
STILL IN A STATE OF FLUX WILL CONT TO MONITOR DVLPMNTS AS PLACEMENT
ON LOCATION OF WRN FLANK STILL UNCERTAIN. OTRWS SIG UPSTREAM NEG
THETA-E ADVTN ASSOCD/W BLDG ARCTIC RIDGING LOOKS TO STIFLE ADDNL
SRN LAKE DVLPMNT UNTIL LT AFTN TIMED W/FURTHER AND MORE FVRBL LL
VEERING INTO SW MI/NW IN.
&&
.SHORT TERM... /TODAY THROUGH SUNDAY NIGHT/
PRIMARY FOCUS REMAINS ON LAKE EFFECT SNOW AMOUNTS AND IMPACTS ACROSS
FAR NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN TODAY THROUGH
SUNDAY MORNING...
A DIGGING UPPER TROUGH AXIS AND EMBEDDED SHORTWAVE ENERGY WILL PIVOT
THROUGH THE SOUTHERN GREAT LAKES REGION THIS MORNING WITH THE CORE
OF COLD AIR (7H TEMPS TO -28C) DROPPING THROUGH THIS AFTERNOON INTO
TONIGHT. THIS WILL RESULT IN EXTREME OVER-LAKE INSTABILITY WITH
IMPRESSIVE LAKE-7H TEMP DIFFERENTIALS NEAR 30C AND UVM/MOISTURE
MAXIMIZED WITHIN THE DGZ THROUGH THE EVENT. HOWEVER...MORE WESTERLY
300 DEGREE LOW LEVEL TRAJECTORIES AND A SUBSTANTIAL DIURNAL
COMPONENT TODAY WILL LIMIT ORGANIZATION (MORE CELLULAR) WITH DRY
UPPER MIDWEST ENTRAINMENT AND LARGE SCALE SUBSIDENCE BEHIND THIS
MORNING`S MID LEVEL WAVE ALSO LIMITING FACTORS FOR SIGNIFICANT SNOW
ACCUMS. THIS DRYING/POOR FETCH COMBO COULD EVEN RESULT IN A PERIOD
OF LITTLE/NO SNOW SHOWER ACTIVITY BY LATE MORNING/EARLY AFTERNOON.
THIS WILL LIKELY KEEP SNOW TOTALS IN CHECK THROUGH 00Z WITH
LOCATIONS NORTH OF HWY 6 IN INDIANA/MI STILL EXPECTING SNOW ACCUMS
BETWEEN 1 AND 4 INCHES. ELSEWHERE...EXPECT VERY COLD CONDITIONS WITH
ISOLATED TO SCATTERED SNOW SHOWERS POSSIBLE...ESPECIALLY EARLY THIS
MORNING ALONG THE SYNOPTIC TROUGH WITH DUSTING TO HALF INCH TYPE
ACCUMS POSSIBLE.
SLIGHT IN-CLOUD VEERING TO A MORE FAVORABLE 320-330 DEGREE
FETCH...LITTLE/NO SHEAR...AND FAVORABLE DIURNAL TIMING SHOULD
COMBINE TO ALLOW AN INTENSE SHORE PARALLEL SNOW BAND TO MATERIALIZE
WITHIN AN INTENSIFYING DIRECT THERMAL CIRCULATION/AGGREGATE SFC
TROUGH TONIGHT. HI-RES GUIDANCE CONTINUES TO SUGGEST MESOLOW
DEVELOPMENT WHICH WILL NO DOUBT DETERMINE WHERE THIS BAND SETS
UP/PIVOTS OVERNIGHT INTO EARLY SUNDAY MORNING. INTENSE SNOWFALL
RATES OF 2-3 INCHES PER HOUR WILL BE POSSIBLE WITHIN THIS BAND.
QUESTIONS OBVIOUSLY AT THIS JUNCTURE REMAIN EXACTLY WHERE THIS SETS
UP AND POSSIBLE INTERFERENCE (FLOW INTERRUPTION) FROM ANY MESOLOW. A
00Z MODEL CONSENSUS DOES FAVOR NORTHERN/EASTERN BERRIEN, WESTERN
CASS MI, AND ST JOE INDIANA AS THE PIVOT POINT WITH THE POTENTIAL
FOR SEVERAL HOURS OF HEAVY SNOW. FOR NOW WILL HOLD SERVE WITH
CURRENT HEADLINES GIVEN UNCERTAINTIES. REGARDLESS THERE IS THE
POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW MAINLY LATER THIS EVENING
INTO THE OVERNIGHT HOURS. ELSEWHERE...MAINLY DRY AND COLD.
WAA WITH RIDGING ALOFT AND BACKING LOW LEVEL TRAJECTORIES WILL BRING
ANY LINGERING LAKE EFFECT SNOW TO AN END BY EARLY SUNDAY AFTERNOON
WITH NO SENSIBLE WX CONCERNS SUNDAY AFTERNOON/NIGHT.
&&
.LONG TERM... /MONDAY THROUGH FRIDAY/
ALL IN ALL LITTLE SIG CHNG FM YDAY ANALYSIS WITH OVERALL INCRSD
CONFIDENCE WRT QPF/TIMING ASSOCD WITH LOW/MODERATE AMPLITUDE NRN
STREAM WAVE /CRNTLY APPROACHING PAC NW/ TO MAINTAIN PROGRESSIVE
NATURE INTO ERLY NEXT WEEK. SYSTEM TRAVERSING SCNTL CAN/NRN PLAINS
MONDAY TO SLOW TUESDAY/INCRSGLY VERTICALLY STACKED AS SRN END/SE CO
FNTL WAVE PROCEEDS INTO OCCLUSAL IN NRN GRTLKS. SOME
DISCOUNT/CAUTION TO THE MORE RAPID NAM/SREF SIGNALS...PER VARIANCE
AS NOTED IN PMDHMD. AT SAME TIME DIFFICULT TO UNDERESTIMATE
SHALLOW/DRY/COLD CP AIR ADVANCE AFFORDED BY POLEWARD CONNECTIVITY AT
SFC/LLVLS OF SUCH INTENSE NRN MANITOBA ANTICYCLONE. ATTEMPT TO
FURTHER DETAIL TIMING OF RAFL ONSET THROUGH CWA WITH SIGNALS OF DEEP
MSTR/UVM HOLDING OFF TIL LATE IN DAY ONCE LATE OPEN GOMEX FEED/NRN
TERMINUS OF HIGHLY INTENSE 925-8H LLJ TO 65 KTS AIMING FM MO
BOOTHILL THROUGH MOUTH OF OH RVR INTO FAR SWRN IN TO DEMAND FORCED
MOIST ASCENT...MOST LIKELY UNTIL LATE AFTN/21 UTC MON TIMEFRAME.
RAPID EWD SHIFT OF FEATURE INTO UPR OH VLY BY 06 UTC TO GRTLY LIMIT
UVM ACRS RGN AFT RAFL SLUG...WITH TRANSITION TO LIGHTER RA/SN MIX TO
SN THROUGH THE NIGHT WITH LITTLE/NO ACCUMS.
THEREAFTER...MINOR LES RESPONSE PER WRLY FLOW AND MUTED MIXED LYR
DEPTH. ALL EYES RMN ON LATE WEEK SYSTEM. SLIGHT NWD SHIFT SFC/ALOFT
NOTED PER MULTIMODEL CONSENSUS...THOUGH CERTAINLY NOT SIG ENOUGH TO
DISMISS. INTMTN/SWRN STATES TROF AT APEX 00 UTC THU/F120. THEREAFTER
HOLD DOUBTS AS TO EXACT TRACK. LOW AMPLITUDE/WEAKNESS NOTED IN
DOWNSTREAM RIDGE THEREAFTER AS SYSTEM EJECTS FM ERN NM INTO CNTL
PLAINS DY6. THIS DOWNSTREAM WEAKNESS COULD AFFORD POTNL TO BIFURCATE
AND MAINTAIN A MORE EWD MOMENTUM INTO DY7. ALSO TREND TWRDS CPC 8-14
ANALOGS COULD SUGGEST A POTNL REXING OF SYSTEM PER WEAK/ANTECEDENT
SRN CANADA/JAMES BAY RIDGE AIDED BY A POS HGHT ANOMOLY PHASE
THEREAFTER INTO DY8. POTNL STILL HOLDS OUT AS BEST SYNOPTIC SYSTEM
SINCE DEC 26 AS THU NIGHT ONSLAUGHT OF INITIAL STRONG ISENT
LIFT/STRONG EVAP/STRONGER DYNAMIC COOLING PROCESSES TO ELICIT RAPID
WETBULB COLLAPSE FOR SN/PSBLY BECMG HVY ACRS SWRN/WRN CWA BY ERLY
FRI. THEREAFTER A DOWNSTREAM RIDGE SPLIT/REX DVLPMNT REMOTELY COULD
OFFER A STALLED DEEP SYSTEM TO SLOWLY WITHER ON VINE ACRS NRN IN/SRN
LWR MI...AT LEAST THROUGH HERO FCSTR EYES. LARGE STANDARD DEVIATION
SPREAD PER MEDIUM RANGE MODEL ACCUMULATIONS. SAN COMPACTION WITH
CLIMATOLOGICAL MEAN NEAR 14/1 RATIOS USED AFFORDED RANGES GNRLY
WITHIN 3-7 INCH RANGE...FWIW AT F144-180.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST /3 AM CST/ SUNDAY FOR
INZ003>005.
MI...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST SUNDAY FOR MIZ079.
LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SUNDAY FOR MIZ077-078.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...STEINWEDEL
LONG TERM...MURPHY
AVIATION...T
UPDATE...T
AREA FORECAST DISCUSSION
NWS GOODLAND KS
350 PM MST SAT FEB 16 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 144 PM MST SAT FEB 16 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH ACROSS
WESTERN US WITH ITS AXIS CENTERED ALONG THE ROCKY MOUNTAINS...AND A
LARGE SCALE TROUGH ACROSS THE EASTERN US. A SHORTWAVE TROUGH
UPSTREAM OF THE H5 RIDGE IS DEEPENING OVER THE PACIFIC NW COAST.
THE H5 RIDGE IS EXPECTED TO SHIFT EAST WITH A VERY DRY AIRMASS
MOVING OVER OUR CWA. THE SHORTWAVE TROUGH UPSTREAM WILL DIG SOUTH
TOWARDS THE GREAT BASIN OVERNIGHT AND TOWARDS THE CENTRAL ROCKIES
MIDDAY. SURFACE GRADIENT WILL INCREASE AHEAD OF AN APPROACHING COLD
FRONT WITH WINDS INCREASING ACROSS THE SOUTHERN HALF OF THE CWA
THROUGH THE DAY. A PRE-FRONTAL TROUGH AXIS WILL MOVE INTO THE
NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS SUNDAY WITH
WINDS DECREASING ALONG AND IMMEDIATELY BEHIND THIS FEATURE. WITH
STRONG WAA AND DEEP MIXING EXPECTED WE ARE LIKELY TO SEE NEAR RECORD
HIGH TEMPERATURES IN THE MID/UPPER 60S...POSSIBLY 70F.
VERY LOW TD VALUES ARE ALSO EXPECTED BY SUNDAY AFTERNOON...WITH RH
VALUES DROPPING TO RFW CRITERIA ACROSS MOST OF THE CWA DURING THE
AFTERNOON. WE COULD SEE SINGLE DIGIT RH VALUES IN THE SOUTH AND
WEST. AT THIS TIME...I AM MOST CONFIDENT IN WIND/RH CROSSOVER SOUTH
OF I-70 WHERE I HAVE ISSUED RED FLAG WARNING. WITH THE POSSIBILITY
OF WINDS DIMINISHING ACROSS THE NORTH...I AM NOT AS CONFIDENT IN
WIND/RH CROSSOVER...SO I ISSUED A FIRE WEATHER WATCH ACROSS THE
CENTRAL AND NORTHEASTERN PARTS OF THE CWA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 219 PM MST SAT FEB 16 2013
LONG TERM FOCUS IS ON THE LOW PRESSURE SYSTEM MOVING EAST OF THE
ROCKIES AND ACROSS THE CENTRAL HIGH PLAINS REGION WEDNESDAY NIGHT
THROUGH THURSDAY NEXT WEEK.
SUNDAY NIGHT A COLD FRONT MOVES THROUGH THE REGION WITH THE UPPER
TROUGH MOVING THROUGH THE CENTRAL ROCKIES TO MOVE ACROSS THE
CENTRAL HIGH PLAINS BY MID DAY ON MONDAY. SINCE CONDITIONS WILL BE
MOSTLY DRY...EXPECT ONLY AN INCREASE IN CLOUDS AND COOLER
TEMPERATURES WITHOUT ANY PRECIPITATION. HIGH TEMPERATURES WILL BE
ABOUT 20 DEGREES COOLER ON MONDAY THAN THEY WERE ON SUNDAY. GUSTY
NORTHWEST WINDS ARE ALSO EXPECTED DURING THE DAY BEHIND THE FRONT.
SHORT WAVE RIDGING ALOFT IS EXPECTED ON TUESDAY AND TUESDAY NIGHT
IN THE WAKE OF THE EXITING TROUGH AND PRIOR TO THE NEXT
APPROACHING LOW PRESSURE CENTER DIVING SOUTH ALONG THE WEST COAST
THAT MOVES INTO THE FAR SOUTHWEST UNITED STATES BY WEDNESDAY
MORNING. A COOL HIGH PRESSURE AREA REMAINS OVER THE NORTHERN
PLAINS AND EXTENDS INTO THE CENTRAL PLAINS THROUGH
WEDNESDAY...TRANSPORTING LOW LEVEL MOISTURE INTO THE SOUTHERN AND
CENTRAL HIGH PLAINS REGIONS WITH THE POSSIBILITY OF A LITTLE
INSTABILITY MOVING OVER THE FORECAST AREA TO PRODUCE A MIX OF RAIN
AND SNOW SHOWERS AND POSSIBLY EVEN A RUMBLE OF THUNDER LATE IN THE
DAY ON WEDNESDAY IN THE WARM SECTOR AHEAD OF THE MAIN UPPER LOW
CENTER AS IT MOVES EAST OF THE ROCKIES IN THE VICINITY OF
SOUTHEAST COLORADO. HAVE LEFT THE MENTION OF THUNDER OUT FOR NOW.
RAIN TRANSITIONS TO SNOW OVERNIGHT WEDNESDAY NIGHT AND EARLY
THURSDAY MORNING AS COLDER AIR IS BROUGHT FURTHER SOUTH ACROSS THE
HIGH PLAINS. DEPENDING UPON THE TIMING OF THE CHANGE OVER TO SNOW
AND THE AMOUNT OF MOISTURE AND INSTABILITY THAT ACTUALLY AFFECTS
THE FORECAST AREA...THERE IS THE POTENTIAL FOR A SIGNIFICANT
SNOWFALL ACROSS THE CENTRAL HIGH PLAINS REGION MAINLY ACROSS THE
NORTHEAST HALF OF THE FORECAST AREA. IT`S STILL FAR ENOUGH OUT
THAT CONFIDENCE IS A LITTLE LACKING...BUT MODEL SOLUTIONS HAVE
BEEN ADVERTISING REASONABLY SIMILAR SOLUTIONS THROUGH THE LATTER
PORTIONS OF NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 350 PM MST SAT FEB 16 2013
VFR THROUGH THE PERIOD AT KGLD AND KMCK. W/SW WINDS UNDER 10KTS AT
THE START OF THE PERIOD WILL REMAIN SO THROUGH 17Z OR SO BEFORE
INCREASING AND BECOMING GUSTY FROM THE SOUTHWEST BY 19Z AND
CONTINUING THROUGH 23Z OR SO. PEAK GUSTS DURING THE AFTERNOON AT
KGLD AROUND 26KTS WITH 20KTS OR SO AT KMCK. LITTLE TO NO
CLOUDINESS THROUGH MUCH OF THE PERIOD WITH ONLY AN INCREASE IN
CIRRUS FROM THE NORTHWEST BY MID TO LATE AFTERNOON.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...RED FLAG WARNING FROM 11 AM MST /NOON CST/ TO 6 PM MST /7 PM
CST/ SUNDAY FOR KSZ027>029-041-042.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR KSZ003-004-013>016.
CO...RED FLAG WARNING FROM 11 AM TO 6 PM MST SUNDAY FOR COZ254.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR COZ253.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
242 PM MST SAT FEB 16 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 144 PM MST SAT FEB 16 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH ACROSS
WESTERN US WITH ITS AXIS CENTERED ALONG THE ROCKY MOUNTAINS...AND A
LARGE SCALE TROUGH ACROSS THE EASTERN US. A SHORTWAVE TROUGH
UPSTREAM OF THE H5 RIDGE IS DEEPENING OVER THE PACIFIC NW COAST.
THE H5 RIDGE IS EXPECTED TO SHIFT EAST WITH A VERY DRY AIRMASS
MOVING OVER OUR CWA. THE SHORTWAVE TROUGH UPSTREAM WILL DIG SOUTH
TOWARDS THE GREAT BASIN OVERNIGHT AND TOWARDS THE CENTRAL ROCKIES
MIDDAY. SURFACE GRADIENT WILL INCREASE AHEAD OF AN APPROACHING COLD
FRONT WITH WINDS INCREASING ACROSS THE SOUTHERN HALF OF THE CWA
THROUGH THE DAY. A PRE-FRONTAL TROUGH AXIS WILL MOVE INTO THE
NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS SUNDAY WITH
WINDS DECREASING ALONG AND IMMEDIATELY BEHIND THIS FEATURE. WITH
STRONG WAA AND DEEP MIXING EXPECTED WE ARE LIKELY TO SEE NEAR RECORD
HIGH TEMPERATURES IN THE MID/UPPER 60S...POSSIBLY 70F.
VERY LOW TD VALUES ARE ALSO EXPECTED BY SUNDAY AFTERNOON...WITH RH
VALUES DROPPING TO RFW CRITERIA ACROSS MOST OF THE CWA DURING THE
AFTERNOON. WE COULD SEE SINGLE DIGIT RH VALUES IN THE SOUTH AND
WEST. AT THIS TIME...I AM MOST CONFIDENT IN WIND/RH CROSSOVER SOUTH
OF I-70 WHERE I HAVE ISSUED RED FLAG WARNING. WITH THE POSSIBILITY
OF WINDS DIMINISHING ACROSS THE NORTH...I AM NOT AS CONFIDENT IN
WIND/RH CROSSOVER...SO I ISSUED A FIRE WEATHER WATCH ACROSS THE
CENTRAL AND NORTHEASTERN PARTS OF THE CWA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 219 PM MST SAT FEB 16 2013
LONG TERM FOCUS IS ON THE LOW PRESSURE SYSTEM MOVING EAST OF THE
ROCKIES AND ACROSS THE CENTRAL HIGH PLAINS REGION WEDNESDAY NIGHT
THROUGH THURSDAY NEXT WEEK.
SUNDAY NIGHT A COLD FRONT MOVES THROUGH THE REGION WITH THE UPPER
TROUGH MOVING THROUGH THE CENTRAL ROCKIES TO MOVE ACROSS THE
CENTRAL HIGH PLAINS BY MID DAY ON MONDAY. SINCE CONDITIONS WILL BE
MOSTLY DRY...EXPECT ONLY AN INCREASE IN CLOUDS AND COOLER
TEMPERATURES WITHOUT ANY PRECIPITATION. HIGH TEMPERATURES WILL BE
ABOUT 20 DEGREES COOLER ON MONDAY THAN THEY WERE ON SUNDAY. GUSTY
NORTHWEST WINDS ARE ALSO EXPECTED DURING THE DAY BEHIND THE FRONT.
SHORT WAVE RIDGING ALOFT IS EXPECTED ON TUESDAY AND TUESDAY NIGHT
IN THE WAKE OF THE EXITING TROUGH AND PRIOR TO THE NEXT
APPROACHING LOW PRESSURE CENTER DIVING SOUTH ALONG THE WEST COAST
THAT MOVES INTO THE FAR SOUTHWEST UNITED STATES BY WEDNESDAY
MORNING. A COOL HIGH PRESSURE AREA REMAINS OVER THE NORTHERN
PLAINS AND EXTENDS INTO THE CENTRAL PLAINS THROUGH
WEDNESDAY...TRANSPORTING LOW LEVEL MOISTURE INTO THE SOUTHERN AND
CENTRAL HIGH PLAINS REGIONS WITH THE POSSIBILITY OF A LITTLE
INSTABILITY MOVING OVER THE FORECAST AREA TO PRODUCE A MIX OF RAIN
AND SNOW SHOWERS AND POSSIBLY EVEN A RUMBLE OF THUNDER LATE IN THE
DAY ON WEDNESDAY IN THE WARM SECTOR AHEAD OF THE MAIN UPPER LOW
CENTER AS IT MOVES EAST OF THE ROCKIES IN THE VICINITY OF
SOUTHEAST COLORADO. HAVE LEFT THE MENTION OF THUNDER OUT FOR NOW.
RAIN TRANSITIONS TO SNOW OVERNIGHT WEDNESDAY NIGHT AND EARLY
THURSDAY MORNING AS COLDER AIR IS BROUGHT FURTHER SOUTH ACROSS THE
HIGH PLAINS. DEPENDING UPON THE TIMING OF THE CHANGE OVER TO SNOW
AND THE AMOUNT OF MOISTURE AND INSTABILITY THAT ACTUALLY AFFECTS
THE FORECAST AREA...THERE IS THE POTENTIAL FOR A SIGNIFICANT
SNOWFALL ACROSS THE CENTRAL HIGH PLAINS REGION MAINLY ACROSS THE
NORTHEAST HALF OF THE FORECAST AREA. IT`S STILL FAR ENOUGH OUT
THAT CONFIDENCE IS A LITTLE LACKING...BUT MODEL SOLUTIONS HAVE
BEEN ADVERTISING REASONABLY SIMILAR SOLUTIONS THROUGH THE LATTER
PORTIONS OF NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1031 AM MST SAT FEB 16 2013
VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT GLD AND MCK. A
FEW MID TO HIGH LEVEL CLOUDS /AROUND 10KFT AGL/ WILL DEVELOP THIS
AFTERNOON BUT OTHERWISE SKIES WILL BE CLEAR THROUGH THE FORECAST
PERIOD. BREEZY NORTHWEST WINDS THIS AFTERNOON /20KTS GUSTING TO
NEAR 30KTS/ WILL DECREASE THIS EVENING...BECOMING LIGHT AND
VARIABLE THOUGH GENERALLY OUT OF THE WEST. EARLY TOMORROW WINDS
WILL BE LIGHT OUT OF THE SOUTHWEST AS A SURFACE THROUGH SETS UP
NEAR THE KANSAS- COLORADO BORDER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...RED FLAG WARNING FROM 11 AM MST /NOON CST/ TO 6 PM MST /7 PM
CST/ SUNDAY FOR KSZ027>029-041-042.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR KSZ003-004-013>016.
CO...RED FLAG WARNING FROM 11 AM TO 6 PM MST SUNDAY FOR COZ254.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR COZ253.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
145 PM MST SAT FEB 16 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 144 PM MST SAT FEB 16 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH ACROSS
WESTERN US WITH ITS AXIS CENTERED ALONG THE ROCKY MOUNTAINS...AND A
LARGE SCALE TROUGH ACROSS THE EASTERN US. A SHORTWAVE TROUGH
UPSTREAM OF THE H5 RIDGE IS DEEPENING OVER THE PACIFIC NW COAST.
THE H5 RIDGE IS EXPECTED TO SHIFT EAST WITH A VERY DRY AIRMASS
MOVING OVER OUR CWA. THE SHORTWAVE TROUGH UPSTREAM WILL DIG SOUTH
TOWARDS THE GREAT BASIN OVERNIGHT AND TOWARDS THE CENTRAL ROCKIES
MIDDAY. SURFACE GRADIENT WILL INCREASE AHEAD OF AN APPROACHING COLD
FRONT WITH WINDS INCREASING ACROSS THE SOUTHERN HALF OF THE CWA
THROUGH THE DAY. A PRE-FRONTAL TROUGH AXIS WILL MOVE INTO THE
NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS SUNDAY WITH
WINDS DECREASING ALONG AND IMMEDIATELY BEHIND THIS FEATURE. WITH
STRONG WAA AND DEEP MIXING EXPECTED WE ARE LIKELY TO SEE NEAR RECORD
HIGH TEMPERATURES IN THE MID/UPPER 60S...POSSIBLY 70F.
VERY LOW TD VALUES ARE ALSO EXPECTED BY SUNDAY AFTERNOON...WITH RH
VALUES DROPPING TO RFW CRITERIA ACROSS MOST OF THE CWA DURING THE
AFTERNOON. WE COULD SEE SINGLE DIGIT RH VALUES IN THE SOUTH AND
WEST. AT THIS TIME...I AM MOST CONFIDENT IN WIND/RH CROSSOVER SOUTH
OF I-70 WHERE I HAVE ISSUED RED FLAG WARNING. WITH THE POSSIBILITY
OF WINDS DIMINISHING ACROSS THE NORTH...I AM NOT AS CONFIDENT IN
WIND/RH CROSSOVER...SO I ISSUED A FIRE WEATHER WATCH ACROSS THE
CENTRAL AND NORTHEASTERN PARTS OF THE CWA.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 241 AM MST SAT FEB 16 2013
SUNDAY NIGHT-MONDAY NIGHT...LARGE SCALE FORCING FOR ASCENT WILL
INCREASE SHARPLY OVERNIGHT SUNDAY AS STRONG FRONTAL CIRCULATION
EXPECTED BEHIND THE SFC FRONT AND COINCIDES WELL WITH STRONGEST DIV
Q AND PV ADVECTION ACROSS MUCH OF THE CWA. THETA E LAPSE RATES DO
INDICATE CONDITIONAL INSTABILITY WILL BE PRESENT AT THIS TIME...BUT
GIVEN T-TD DEPRESSIONS OF AIR MASS IN ADVANCE OF THIS SYSTEM MAKE ME
DOUBTFUL THAT WIDESPREAD SATURATION WILL DEVELOP TO TAKE ADVANTAGE
OF POTENTIAL INSTABILITY. WILL KEEP POPS IN THE 5-10 PERCENT RANGE
UNTIL MORE CONFIDENT ABOUT POTENTIAL SATURATION IN THE H7-H5 LAYER
SUNDAY NIGHT AND MONDAY MORNING. PERIOD OF SUBSIDENCE WILL DEVELOP
BEHIND THIS SYSTEM AND WHILE THERE WILL BE A PERIOD OF STRONG
FRONTOGENESIS LINGERING ACROSS THE AREA...DO NOT THINK FORCED ASCENT
WILL BE STRONG ENOUGH TO PRODUCE ANY MEANINGFUL PRECIPITATION.
TUESDAY THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL START OUT THE
PERIOD ON TUESDAY WITH A BACKDOOR COLD FRONT MOVING IN DURING THE
NIGHT.
WEDNESDAY AN UPPER LEVEL LONG WAVE TROUGH WILL APPROACH THE
TRI-STATE AREA. DURING THE DAY THE 850-700MB LAYER SATURATES AND
STRONG ISENTROPIC LIFT DEVELOPS OVER THE AREA AHEAD OF THE LONG WAVE
TROUGH. WITH TEMPERATURES BELOW FREEZING FOR MUCH OF THE
AREA...FREEZING DRIZZLE MAY DEVELOP. WILL ONLY MENTION A RAIN/SNOW
MIX AT THIS TIME RANGE INSTEAD.
WEDNESDAY NIGHT COOLER AIR MOVES IN AS THE UPPER LEVEL TROUGH MOVES
CLOSER TO THE AREA CAUSING THE PRECIPITATION TO CHANGE TO SNOW BY
THE OVERNIGHT HOURS. DURING THE OVERNIGHT HOURS THE UPPER LEVEL
TROUGH AND SURFACE LOW MOVE OVER THE AREA...CAUSING THE LIFT TO
PEAK. WILL LIKELY SEE THE MOST SNOWFALL OCCUR LATE WEDNESDAY NIGHT
THROUGH EARLY THURSDAY MORNING AS THE SURFACE LOW AND UPPER LEVEL
TROUGH MOVE ACROSS THE AREA.
THURSDAY MORNING A STRONG COLD FRONT MOVES IN BEHIND THE SURFACE LOW
AS IT MOVES EAST. BEHIND THE FRONT NORTHWEST WINDS WILL QUICKLY
STRENGTHEN. MEANWHILE SNOWFALL WILL TAPER OFF FROM WEST TO EAST AS
THE WINTER STORM SYSTEM MOVES OUT OF THE AREA...COMING TO AN END BY
THE OVERNIGHT HOURS. CURRENTLY LOOKS LIKE THE WINDS WILL STRENGTHEN AS
THE SNOWFALL BEGINS TO WIND DOWN WHICH WILL HELP REDUCE THE IMPACTS
OF THE STORM.
FRIDAY LOOKS DRY AS A SHORT WAVE RIDGE MOVES OVER THE AREA AHEAD OF
THE NEXT UPPER LEVEL TROUGH MOVING ACROSS THE DESERT SOUTHWEST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1031 AM MST SAT FEB 16 2013
VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT GLD AND MCK. A
FEW MID TO HIGH LEVEL CLOUDS /AROUND 10KFT AGL/ WILL DEVELOP THIS
AFTERNOON BUT OTHERWISE SKIES WILL BE CLEAR THROUGH THE FORECAST
PERIOD. BREEZY NORTHWEST WINDS THIS AFTERNOON /20KTS GUSTING TO
NEAR 30KTS/ WILL DECREASE THIS EVENING...BECOMING LIGHT AND
VARIABLE THOUGH GENERALLY OUT OF THE WEST. EARLY TOMORROW WINDS
WILL BE LIGHT OUT OF THE SOUTHWEST AS A SURFACE THROUGH SETS UP
NEAR THE KANSAS- COLORADO BORDER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...RED FLAG WARNING FROM 11 AM MST /NOON CST/ TO 6 PM MST /7 PM
CST/ SUNDAY FOR KSZ027>029-041-042.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR KSZ003-004-013>016.
CO...RED FLAG WARNING FROM 11 AM TO 6 PM MST SUNDAY FOR COZ254.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR COZ253.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JRM/JTL
AVIATION...JJM
AREA FORECAST DISCUSSION
NWS JACKSON KY
103 PM EST SAT FEB 16 2013
.UPDATE...
ISSUED AT 103 PM EST SAT FEB 16 2013
SCATTERED SNOW SHOWERS ARE PRESENTLY RAMPING UP AS THE SHORTWAVE
ENERGY DIVES SOUTHEAST INTO EASTERN KENTUCKY. HRRR SEEMS TO HAVE A
PRETTY GOOD HANDLE ON THINGS THIS AFTERNOON AND SHOWS A SUBSTANTIAL
WEAKENING TREND AROUND SUNSET THIS EVENING AS WE WOULD EXPECT.
THUS...GOING TO KEEP THE HIGHEST POPS IN THE NEXT 2 TO 4 HOURS...THEN
TRAIL THINGS BACK TO FLURRIES TONIGHT. BASED ON THE LACK OF ACTIVITY
UPSTREAM...THE ONLY SUPPORT FOR ANY ACTIVITY TONIGHT WILL BE UPSLOPE
FLOW INTO THE HIGHER TERRAIN. MADE SOME ADJUSTMENTS TO TIMING AND
TRENDS...BUT NO FORECAST UPDATE IS NEEDED AT THIS TIME.
UPDATE ISSUED AT 950 AM EST SAT FEB 16 2013
STILL DEALING WITH SOME FLURRIES NEAR THE VIRGINIA BORDER...WHICH
REMAINS COVERED WITH ONGOING FORECAST. OTHERWISE...LATEST HI RES
MODEL GUIDANCE SUGGEST A SLIGHTLY SLOWER ONSET OF SNOW SHOWER
ACTIVITY THIS AFTERNOON...SO HAVE SLOWED THINGS DOWN A BIT. SNOW
ACCUMULATIONS WILL BE HARD TO COME BY GIVEN SURFACE TEMPERATURES NEAR
FREEZING. THE EXCEPTION WILL BE IN THE HIGH TERRAIN NEAR THE VIRGINIA
BORDER WHERE UP TO A HALF INCH OF SNOW MAY BE POSSIBLE. OUTSIDE OF
THESE MINOR CHANGES...FORECAST IS IN GOOD SHAPE.
UPDATE ISSUED AT 740 AM EST SAT FEB 16 2013
GRIDS WERE UPDATED BASED ON THE LATEST TEMPERATURE AND DEWPOINT
TRENDS. FLURRIES WERE ALSO PUT IN IN THE WEATHER GRIDS INITIALLY NEAR
THE VA BORDER PER RADAR IMAGERY AND COOP REPORTS. OTHERWISE...THE
FORECAST FOR TODAY STILL REMAINS ON TARGET.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 355 AM EST SAT FEB 16 2013
BEHIND A COLD FRONT THAT CROSSED THE REGION ON FRI EVENING...THE
REGION REMAINS IN NW TO NORTHERLY FLOW IN THE LOW LEVELS AND UNDER THE
INFLUENCE OF A DEEPENING TROUGH OVER THE EASTERN CONUS. LOW LEVEL
MOISTURE IS RATHER LIMITED...BUT RADAR RETURNS HINT THAT SOME
FLURRIES MAY BE FALLING FROM THE STRATOCU OVER THE BIG SANDY REGION
AND NEAR THE VA BORDER.
A FEW FLURRIES HAVE BEEN INSERTED IN THE GRIDS PRIOR TO DAWN OVER THE
SOUTHEASTERN CWA IN LINE WITH RECENT RADAR TRENDS. OTHERWISE...A
SHORTWAVE TROUGH WORKING THROUGH AN EASTERN CONUS TROUGH WILL
APPROACH THE REGION TODAY...BRINGING A BIT OF MOISTURE WITH IT...BUT
AS NOTED BY THE PREVIOUS FORECASTER...MOISTURE WILL BE RATHER
SHALLOW. HOWEVER...WITH THE APPROACH OF THE SHORTWAVE TROUGH...COLD
AIR ADVECTION SHOULD LEAD TO STEEPENING LAPSE RATES...AND THE GENERAL
MODEL CONSENSUS IS FOR A PERIOD OF SCATTERED SNOW SHOWERS FROM AROUND
MIDDAY THROUGH EARLY EVENING. BEFORE AND AFTER THIS POINT...FLURRIES
OR ISOLATED SNOW SHOWERS WILL BE POSSIBLE. A COUPLE OF ADDITIONAL
DISTURBANCES AND LINGERING NORTHWEST UPSLOPE FLOW WILL LEAD TO A
THREAT OF A BIT BETTER COVERAGE OF SNOW SHOWERS OVER THE EASTERN CWA
AND NEAR THE VA BORDER DURING MID TO LATE EVENING AND POSSIBLY TOWARD
DAWN ON SUNDAY. ANY SNOW THAT FALLS WILL HAVE A HIGH SNOW TO LIQUID
RATIO PERHAPS AS HIGH AS 20 TO 1...BUT INCREASING SUN ANGLE AND TEMPS
NEARING THE FREEZING MARK SHOULD KEEP ACCUMULATIONS RATHER MINIMAL IN
THE LOWER ELEVATIONS BELOW 1500 FEET TO A BRIEF DUSTING OR COATING OF
SNOW. AT 1500 FEET OR ABOVE AS MUCH AS A HALF OF AN INCH COULD OCCUR
AND ABOVE 2000 FEET AN INCH TO LOCALLY MORE ABOVE 3000 FEET CANNOT BE
RULED OUT FROM THIS.
MOISTURE SHOULD BECOME SHALLOWER BY SUN MORNING AND THIS COMBINED
WITH TEMPS STARTING TO WARM SHOULD END THE THREAT FOR ANY FLURRIES BY
MIDDAY ON SUNDAY. HOWEVER...STRATOCU MAY LINGER LONGER THAN SUGGEST
BY THE 0Z GFS...POSSIBLY INTO THE AFTERNOON AS SUGGESTED BY THE 6Z
NAM. FOR THIS FORECAST...HELD ONTO THE THREAT OF FLURRIES INTO THE
DAY ON SUN IN THE SOUTHEAST AND WENT MORE PESSIMISTIC ON TIMING OF
THE CLEARING ON SUN AS WELL.
AS FOR TEMPERATURES...COLD AIR ADVECTION SHOULD LEAD TO MIN T LIKELY
AFTER SUNRISE THIS MORNING AND MAX T SHOULD BE MORE ON THE ORDER OF
THE 3 HOURLY TEMPS IN THE MOS GUIDANCE AND A FEW DEGREES BELOW MOS
GUIDANCE MAX T. THE PREVIOUS FORECAST MAX T ALREADY HAD THIS IDEA...SO
VERY LITTLE CHANGE WAS MADE. MIN T TONIGHT WERE NOT CHANGED MUCH FROM
THE PREVIOUS FORECAST EITHER AND THEY SHOULD BE ON THE ORDER OF 10
DEGREES BELOW NORMAL. 850 MB TEMPS WILL BE -10C TO -15C WELL INTO THE
DAY ON SUN AND MAX T WILL BE SIMILAR TO SAT...ESPECIALLY IN THE
CENTRAL AND EASTERN CWA WHERE STRATOCU SHOULD BE MOST PERSISTENT. IF
THE LOW CLOUDS LINGER AS THE 6Z NAM SUGGESTS IN THE CENTRAL AND EAST
THEN MAX T MIGHT NOT REACH THE FREEZING MARK IN MANY LOCATIONS IN THE
EASTERN PART OF THE CWA.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 358 AM EST SAT FEB 16 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A PROGRESSIVE BUT FAIRLY
AMPLIFIED PATTERN TO CONTROL ACROSS THE CONUS THROUGH THE LONG TERM.
A DEPARTING DEEP UPPER LEVEL LOW WILL START OUT ACROSS NEW
ENGLAND...WITH THE OHIO AND TENNESSEE VALLEYS ENJOYING A BRIEF DRY
SPELL THANKS TO A TRANSIENT UPPER LEVEL RIDGE. TEMPERATURES WILL
RETURN TO ABOVE NORMAL FOR MONDAY...WITH GUIDANCE TRENDING A BIT
WARMER STILL...WITH HIGHS INTO THE MID 50S.
A SHORT WAVE TROUGH WILL THEN DIG ACROSS THE NORTHERN PLAINS AND THE
NORTHERN GREAT LAKES REGION THROUGH TUESDAY...ESCORTING A COLD FRONT
THROUGH EASTERN KENTUCKY MONDAY NIGHT INTO EARLY TUESDAY MORNING.
THERE ARE STILL SOME TIMING DIFFERENCES WITH THE FRONT...WITH THE
ECMWF REMAINING THE SLOWEST AND THE MAJORITY OF THE REMAINING
GUIDANCE MORE PROGRESSIVE. AS SUCH...HAVE CONTINUED TO CENTER THE
HIGHEST POPS DURING THE OVERNIGHT PERIOD ON MONDAY NIGHT AND THEN
SIDED WITH THE BLENDED GUIDANCE WITH POPS DECREASING RAPIDLY FROM
WEST TO EAST TOWARDS 12Z TUESDAY.
RIDGING WILL BRING MORE DRY WEATHER TO THE AREA FROM TUESDAY
AFTERNOON THROUGH AT LEAST THURSDAY MORNING...ALTHOUGH WITH THE
SURFACE HIGH CENTERED TO THE NORTH...TEMPERATURES WILL REMAIN BELOW
NORMAL...WITH HIGHS RETREATING TO THE LOW AND MID 40S. BY
THURSDAY...THE NEXT SYSTEM TAKES AIM AT THE AREA...THIS TIME OUT OF
THE CENTRAL PLAINS...WITH A WARM FRONT THREATENING OUR AREA WITH
OVERRUNNING PRECIPITATION BY LATE THURSDAY AFTERNOON. THE MODELS
HAVE GENERALLY TRENDED SLOWER WITH THIS SYSTEM COMPARED TO 24 HOURS
AGO...ESPECIALLY THE GFS. AS SUCH...HAVE KEPT THE MAIN SHOT OF THE
RAIN RESERVED FOR THURSDAY NIGHT...ALIGNING CLOSE TO THE BLENDED
GUIDANCE OUTPUT. BY FRIDAY...SOME SHOWERS MAY LINGER IN THE
MORNING...WITH IMPROVING CONDITIONS BY AFTERNOON AND TEMPERATURES
RETURNING TO ABOVE NORMAL READINGS IN THE 50S UNDER FAIRLY BRISK
SOUTHWEST WINDS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 103 PM EST SAT FEB 16 2013
A WEAK DISTURBANCE WILL BRING GRADUALLY LOWERING CEILINGS INTO
EASTERN KENTUCKY TODAY INTO THIS EVENING. HOWEVER...IT LOOKS LIKE THE
WORSE CONDITIONS EXPECTED WILL BE 2500 FOOT MVFR CIGS. SOME QUESTION
AS TO HOW LONG THE LOWER CIGS MAY PLAGUE THE AREA AS THERE IS QUITE A
BIT OF DRY AND CLEARING UPSTREAM. THUS...AFTER THIS EVENING...SKY
FORECAST TONIGHT REMAINS VERY UNCERTAIN. SNOW SHOWER ACTIVITY THIS
AFTERNOON WILL TRAIL OFF TO FLURRIES TONIGHT. COULD BE A FEW STRONG
WIND GUST OUT OF THE WEST-NORTHWEST TODAY...WITH STEADY WEST-
NORTHWEST WINDS CONTINUING THROUGH TONIGHT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
352 PM EST SAT FEB 16 2013
.SHORT TERM...THIS AFTERNOON AND TONIGHT
UPPER LEVEL WAVE AND MID LEVEL COLD POOL HAVE BROUGHT SEVERAL SNOW
SQUALLS TO SOUTHEAST MICHIGAN TODAY...DROPPING A QUICK 1 TO 2 INCHES
OF SNOW ACROSS AREAS ALONG AND SOUTH OF THE INTERSTATE 69 CORRIDOR.
HOWEVER THE SURFACE TROUGH AND PV ANOMALY HAVE YET TO TRACK THROUGH
SOUTHEAST MICHIGAN. THESE FEATURES WILL TRACK THROUGH DURING THE
EVENING HOURS AND TURN WINDS TO A NORTHERLY DIRECTION...BRINGING
COOLER AIR AND LAKE MOISTURE IN FROM LAKE HURON. ALTHOUGH THE DTX
HIRES WRF RUNS DEVELOP AN IMPRESSIVE LAKE EFFECT BAND THAT TRACKS
THROUGH THE THUMB REGION BETWEEN 21Z AND 06Z...MODEL INITIALIZATION
IS VERY POOR AS THE 20Z PANEL INDICATES THERE SHOULD BE AN
IMPRESSIVE BAND JUST OFFSHORE OF HURON COUNTY...WHICH BY THE VISIBLE
SATELLITE IMAGERY IS FAR FROM REALITY. THIS FAILURE IN THE MODEL
LOOKS TO BE THE FAILURE OF A MESOLOW TO DEVELOP ACROSS CENTRAL LAKE
HURON...INSTEAD THE LAKE EFFECT IS IN A NORTHWEST TO SOUTHEAST
ORIENTATION BEHIND THE MAIN SURFACE TROUGH. THIS IS ACTUALLY
DEPICTED RATHER WELL BY THE HRRR MODEL WHICH BRINGS THIS FEATURE
SOUTH THROUGH THE EARLY EVENING HOURS AND DEVELOPS A NORTH-SOUTH
BAND OF LAKE EFFECT SNOW ACROSS THE EASTERN THUMB WITH SIGNIFICANT
ASSISTANCE FROM CONVERGENCE AS NORTH-NORTHWEST WINDS OVER THE LAKE
CONVERGE WITH NORTHEASTERLY WINDS ACROSS SOUTHERN LAKE HURON. THIS
SETUP WOULD BRING SEVERAL INCHES OF ACCUMULATING SNOW TO SANILAC AND
ST. CLAIR COUNTIES DURING THE EVENING HOURS UNTIL LAKE WINDS TURN
MORE NORTHERLY AND CONVERGENCE ALONG THE LAKE BECOMES BROADER. TO
ADD TO THE CONFUSION THE NAM MODEL IS VERY BRIEF WITH THE
CONVERGENCE AND KEEPS MOST OF THE LAKE EFFECT SNOW OFFSHORE DURING
THE EVENING HOURS.
GIVEN THE GOOD INITIALIZATION INCLINATION IS TO LEAN TOWARDS THE
HRRR SOLUTION AS EAST-WEST BANDS TEND TO TRANSITION TO NORTH-SOUTH
AS THEY ENCOUNTER THE TOPOGRAPHY OF THE THUMB REGION...HOWEVER
CANNOT RULE OUT THE POSSIBILITY OF A MESOLOW FORMING AND TRACKING
FARTHER INLAND THAN SANILAC AND ST. CLAIR COUNTIES. THEREFORE WILL
HANG ONTO THE WINTER WEATHER ADVISORY FOR THE THUMB REGION AND LET
LATER SHIFTS PARE DOWN THE HEADLINE AS THE NATURE AND ORIENTATION OF
THE LAKE EFFECT BECOME APPARENT DURING THE EVENING HOURS. THE
PREVIOUS FORECAST AMOUNTS STILL LOOK SOLID IN THIS REGION WITH A
GOOD 2 TO 4 INCHES EXPECTED WITH ISOLATED 6 INCH AMOUNTS NEAR THE
LAKE HURON SHORELINE AREAS.
&&
.LONG TERM...SUNDAY THROUGH FRIDAY
VERY STRONG NEGATIVE POTENTIAL VORTICITY ADVECTION FROM RETREATING
LARGE WAVELENGTH UPPER LEVEL TROUGH WILL LEAD TO RAPID 1000-500MB
GEOPOTENTIAL HIGH RISES OVER SOUTHEASTERN MICHIGAN 12-00Z SUNDAY.
THE MAXIMUM OF GEOPOTENTIAL HEIGHT RISES WILL REMAIN OVER THE
SOUTHERN APPALACHIANS IN RESPONSE TO THE BOMBING
NOR`EASTER...HOWEVER...HEIGHT RISE RIDGE AXIS WILL EXTEND NORTHWARD
INTO CENTRAL GREAT LAKES. REMNANT LAKE EFFECT WILL BE ONGOING OVER
SOUTH LAKE HURON THROUGH SUNDAY AFTERNOON BEFORE SWEEPING EASTWARD
DUE TO INCREASING WESTERLY COLUMN FLOW. HIGH TEMPERATURES TOMORROW
WILL BE CONSIDERABLY COLD...SOME 10-13 DEGREES BELOW NORMAL. A
RATHER RAW DAY WITH JUST ENOUGH WIND MAGNITUDE TO ALLOW FOR WIND
CHILL VALUES IN THE SINGLE DIGITS BEFORE NOON...TOPPING OUT BETWEEN
10-15 DEGREES FOR THE AFTERNOON. TYPICAL QUESTION MARK EXISTS
CONCERNING POTENTIAL FOR STRATOCUMULUS TOMORROW. THE AREAS
POSITION/PROXIMITY WITHIN EDGE OF RETREATING TROUGH AND OVERALL
ARCTIC AIRMASS SUGGESTS SUNSHINE WILL GREET US IN THE MORNING. THIS
CERTAINLY HAS SUPPORT WHEN LOOKING AT SATELLITE IMAGERY OVER
NORTHERN MINNESOTA. THE MODELED INVERSION AT ROUGHLY 5 KFT AGL IS
INTERESTING AS THE SOLUTION SHOWS NO MOISTURE TRAPPED WITHIN THE
STABLE STRATIFIED LAYER IMMEDIATELY ABOVE INVERSION BASE OR EVEN AT
THE INVERSION BASE ITSELF. WILL CONTINUE WITH THE INHERITED FORECAST
WHICH CALLS FOR SUNSHINE TOMORROW.
MODELS ARE COMING INTO AN AGREEMENT WITH THE SYSTEM THAT WILL
APPROACH THE AREA MONDAY NIGHT. OVERALL...SYSTEM DYNAMICAL SUPPORT
APPEARS ABOVE AVERAGE AS THE SOUTHERN EXTENSION OF THE MIDLEVEL
TROUGH WILL BECOME LINKED TO SOUTHERN STREAM JET STREAM ENERGY OVER
THE FOUR CORNERS AREA SUNDAY NIGHT. THE TROUGH AXIS WHICH WILL BEGIN
AT A POSITIVE TILT WILL TURN NEUTRAL MONDAY NIGHT AND EVENTUALLY
NEGATIVE BY TUESDAY MORNING. THE PRECEDING WARM AIR ADVECTION...WING
OF ISENTROPIC LIFT IS SHOWN TO BE DRY. IT WILL REQUIRE ACTUAL
MOISTURE TRANSPORT AND UPPER LEVEL JET SUPPORT TO GET PRECIPITATION
GOING. DELAYED PRECIPITATION ONSET TIMING A FEW HOURS...NOW EXPECTED
MAINLY FOR THE FIRST HALF OF MONDAY NIGHT. THE GFS SOLUTION AND
RESULTANT PRECIPITATION TYPE SEEMS HIGHLY SUSPECT GIVEN THE OVERALL
HEIGHT PATTERN AND FORECASTED WIND FIELD. REST OF THE MEDIUM RANGE
SUITE SUGGESTS THAT A SUBSTANTIAL WARM LAYER FROM SFC-5 KFT AGL WILL
SLIDE IN SUPPORTING A RAPID TRANSITION TO RAIN. FROM THIS VANTAGE
POINT THIS SYSTEM HAS THE POTENTIAL TO BECOME A HIGHER IMPACT WIND
EVENT. RIGHT NOW...FORECASTED VALUES OF UPWARDS OF 30 KNOTS SEEMS
GOOD...WITH ALL THE MAIN FEATURE SLIGHTLY OUT OF PHASE. SUBSEQUENT
SHIFTS CAN FINE TUNE THIS.
&&
.MARINE...
OTHER THAN AN ACTIVE SNOW SHOWER PATTERN TONIGHT...MARINE CONDITIONS
WILL BE FAVORABLE THROUGH SUNDAY IN TERMS OF WIND OVER ALL MARINE
AREAS AND WAVES OVER THE OPEN WATERS OF LAKE HURON. AFTER THAT...A
STRONG LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP OVER THE PLAINS
AND MIDWEST AND MOVE THROUGH THE GREAT LAKES MONDAY AND TUESDAY.
MILD AIR SPREADING NORTHWARD AHEAD OF THE SYSTEM WILL BRING RAIN TO
ALL AREAS EXCEPT THE FAR NORTH REACHES OF LAKE HURON. A STRONG COLD
FRONT IS EXPECTED TO BRING A SHARP WESTERLY WIND SHIFT TUESDAY
MORNING BUT SPEEDS ARE EXPECTED TO REMAIN BELOW GALE FORCE FOR
NOW. STRONG NORTHWEST WIND TRAILING THE FRONT WILL EASE IN SPEED
DURING WEDNESDAY.
&&
.AVIATION...ISSUED 1226 PM EST SAT FEB 16 2013
//DISCUSSION...
CEILINGS LOOK TO BE PREDOMINATELY MVFR AS A WEAK SURFACE LOW AND
ASSOCIATED COLD FRONT SINK SOUTH THROUGH THE AREA THIS AFTERNOON AND
EVENING. THERE WILL BE A CONTINUED THREAT FOR SNOW SHOWERS...WITH
CONVECTIVE NATURE TO THE ACTIVITY LEAD TO BRIEF IFR BURSTS...LEADING
TO 1 TO 3 INCHES OF ACCUMULATIONS BY THE TIME THE SNOW ENDS LATE
THIS EVENING. SKIES LOOK TO BE CLEARING OUT OVERNIGHT AS SURFACE
HIGH SETTLES OVER WESTERN LOWER MICHIGAN...MAINTAIN GENERALLY LIGHT
WINDS. WINDS TODAY WILL ALSO BE VERY LIGHT AND VARIABLE WITH THE
SURFACE LOW TRACKING THROUGH.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING HEIGHTS BELOW 5000 FEET THROUGH THIS
EVENING.
* HIGH CONFIDENCE IN PRECIPITATION TYPE BEING SNOW.
* MEDIUM CONFIDENCE IN CIGS/VSBYS ABOVE 200 FT AND 1/2SM THIS
AFTERNOON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY...MIZ049-MIZ054-MIZ062...UNTIL 10 PM
SATURDAY.
WINTER WEATHER ADVISORY...MIZ055-MIZ063...UNTIL 2 AM SUNDAY.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KURIMSKI
LONG TERM....CB
MARINE.......KURIMSKI
AVIATION.....KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
132 PM EST SAT FEB 16 2013
.SYNOPSIS...
ISSUED AT 330 AM EST SAT FEB 16 2013
OCCASIONAL SNOW SHOWERS WILL CONTINUE TODAY AND INTO THIS EVENING.
THE SNOW WILL BE HEAVY AT TIMES. LAKE SHORE AREAS WILL PICK UP
ANOTHER 2 TO 4 INCHES...WHILE INLAND AREAS SEE 1 TO 2 INCHES. THE
SNOW IS EXPECTED TO DIMINISH AFTER MIDNIGHT.
BY MONDAY LOW PRESSURE WILL MOVE INTO THE UPPER MIDWEST. THIS
SYSTEM WILL BRIEFLY BRING TEMPERATURES UP TO AROUND 40 BY MONDAY
AFTERNOON. A PERIOD OF RAIN IS EXPECTED MONDAY AFTERNOON...THAT
WILL TURN TO SNOW MONDAY NIGHT AND CONTINUE ON TUESDAY. MORE SNOW
LOOKS LIKELY BY THURSDAY NIGHT AND FRIDAY.
&&
.UPDATE...
ISSUED AT 132 PM EST SAT FEB 16 2013
AS DISCUSSED IN THE RECENT WSW UPDATE...EXPECT MASON AND OCEANA
TO SEE A MARKED DROP IN SNOW INTENSITY LATER THIS AFTERNOON BASED
ON RAP MODEL GUIDANCE. FOR NOW THOUGH...RADAR RETURNS AT
SIGNIFICANT RANGE BEYOND LUDINGTON COMBINED WITH IMPRESSIVE BANDS
NOTED ON IR SATELLITE INDICATE INTENSE SNOWFALL IS STILL LIKELY
ONGOING.
HAVE DROPPED LAKE...NEWAYGO...AND KENT COUNTIES FROM THE ADVISORY.
ACCUMULATIONS WERE LIMITED IN THESE AREAS. THE REMAINING THREE INLAND
COUNTIES (BARRY...KALAMAZOO... AND CALHOUN) ARE KEPT IN AN ADVISORY
TO ACCOUNT MOSTLY FOR RAPID VISIBILITY CHANGES. BIV RECENTLY
DROPPED TO 1/4 MILE UNDER ONE OF THE STRONGER BANDS.
ACCUMULATING SNOW SHOULD NOT BE SO MUCH OF AN ISSUE AWAY FROM THE
LAKESHORE THE REST OF TODAY. PRECIPITATION GENERALLY APPEARS MORE
CELLULAR ON RADAR. THIS COMBINED WITH MID-FEBRUARY DAYTIME
INSOLATION IS KEEPING ACCUMULATIONS IN CHECK.
UPDATE ISSUED AT 900 AM EST SAT FEB 16 2013
AFTER FURTHER CONSIDERATION...WILL BE UPGRADING MASON AND OCEANA
TO A WARNING. RAP GUIDANCE SUGGESTS THAT AFTER A LULL THIS MORNING...
ANOTHER SIGNIFICANT BAND MAY EXTEND FROM THESE COUNTIES THROUGH
MUSKEGON...ALLEGAN...AND KALAMAZOO COUNTIES.
UPDATE ISSUED AT 848 AM EST SAT FEB 16 2013
HAVE RECEIVED RECENT 8-12" SNOW REPORTS FROM SEVERAL LOCATIONS IN
MASON AND OCEANA COUNTIES BENEATH AN AREA OF SATELLITE IR
TEMPERATURES THAT WERE COLDER THAN -30C BETWEEN 11-12Z. 830 AM
AWOS OBSERVATION AT HART INDICATES VISIBILITY BELOW 1/4 MILE.
SUSPECT STRONG FRONTOGENETIC FORCING HAS BEEN AT PLAY AS
TEMPERATURES AT RQB AND CAD HAD DROPPED AS MUCH AS 10 DEGREES OR
MORE OVER THE PAST FEW HOURS. PRESENT THINKING IS THAT FGEN
FORCING SHOULD DECREASE ALONG WITH MOST INTENSE SNOW THROUGH 10
AM. THIS IS SUPPORTED BY THE 16/09Z RUN OF THE HRRR...WHICH TAPERS
PRECIP AND MOVES IT INLAND THROUGH 15Z. BELIEVING WE ARE ON A
DOWNWARD TREND AFTER A PEAK IN SNOWFALL INTENSITY...WILL KEEP THE
ADVISORY GOING IN THIS AREA AND UPDATE WITH THE LATEST THINKING.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 330 AM EST SAT FEB 16 2013
A RATHER DISORGANIZED PATTERN SO FAR EARLY THIS MORNING. A SURFACE
TROUGH HAS BEEN CROSSING THE LAKE EARLY THIS MORNING AND THE WIND
PATTERN AROUND THIS TROUGH HAS BEEN DISRUPTING ANY ORGANIZED LAKE
EFFECT BANDS. THERE HAS BEEN A PERSISTENT BAND ACROSS THE NW
COUNTIES NEAR LUDINGTON AND WHITEHALL...BUT OTHER SNOW BANDS HAVE
BEEN FAIRLY TRANSITORY...KEEPING ACCUMS DOWN.
THE SURFACE TROUGH LINGERS OVER THE AREA MUCH OF TODAY...SO FEEL WE
MAY STRUGGLE TO GET PERSISTENT LES BANDS. RAP13 LOW LEVEL
CONVERGENCE FIELDS SUGGEST THE LDM BAND MAY HOLD PAT MUCH OF THE
DAY. IF THIS HOLDS TRUE...THIS BAND COULD PUT DOWN ANOTHER FOUR
INCHES OR SO. A BETTER FLAIR UP IS INDICATED TOWARD 16Z FOR THE SW
COUNTIES AND THIS IS PAINTED TO LAST THROUGH MUCH OF THE AFTERNOON.
ALSO OF INTEREST IS A SYNOPTIC CONVERGENCE BAND THAT FLAIRS UP NORTH
OF THE SURFACE TROUGH ALONG HIGHWAY 10 BY MID TO LATE AFTERNOON
TODAY. IF THIS HOLDS TRUE THERE COULD BE A BURST OF SNOW ACROSS ALL
OF THE NORTHERN COUNTIES INTO THIS EVENING.
NEEDLESS TO SAY A RATHER COMPLEX PATTERN FOR TODAY. THOUGHT ABOUT
DROPPING SOME OF THE COUNTIES IN THE ADVISORY AS THE LAKE EFFECT
DOES NOT LOOK AS ROBUST ANYMORE. HOWEVER SINCE SNOW WILL STILL
OCCUR...IT IS SORT OF HARD TO DROP HEADLINES IN THE MIDDLE OF AN
EVENT. SO WILL LEAVE THE ADVISORY AS IS...ALTHOUGH WILL HIGHLIGHT
SLIGHTLY LESS ACCUMS. ON THE OTHER HAND...INLAND AREAS COULD SEE A
BIT MORE SNOW THEN WHAT IS CURRENTLY IN THE FORECAST DUE TO THE
SYNOPTIC FEATURES. SO HAVE BUMPED UP ACCUMS A BIT INLAND...
ESPECIAL NEAR HIGHWAY 10 TO COVER THE POSSIBLE CONVERGENCE BURST
LATE TODAY INTO THIS EVENING. THE SNOW SHOULD BE DWINDLING AFTER
MIDNIGHT AS THE SYSTEM PULLS AWAY AND INVERSION LEVELS COME DOWN.
WILL CONTINUE WITH THE CHANCE POPS ON SUNDAY ALONG THE LAKE SHORE.
WINDS WILL PIVOT FROM THE NNW EARLY IN THE DAY TO SW TOWARD MID
DAY. THIS SHOULD PUSH ANY LAKE BAND INLAND...PRODUCING A BRIEF SNOW
SHOWER MAINLY WEST OF U.S. 131.
THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE MONDAY SYSTEM...
BRINGING IT IN QUICKER. HAVE INCREASED POPS TO LIKELY BY MID TO
LATE AFTERNOON. SHOULD BE WARM ENOUGH OF MOSTLY RAIN...ALTHOUGH A
MIX SHOULD FALL OVER CENTRAL LOWER.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EST SAT FEB 16 2013
ACTIVE WEATHER PATTERN NEXT WEEK WITH TWO STORMS TO WATCH. A CLIPPER
MOVES MOVES EAST MONDAY NIGHT WITH RAIN AND SNOW MIX CHANGING TO
SNOW...FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY AFTERNOON
INTO WEDNESDAY.
SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON
WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM TAKES
SHAPE ACROSS THE PLAINS AND MOVES NORTHEAST SPREADING A BAND OF SNOW
INTO LOWER MICHIGAN BY LATE THURSDAY. SNOW COULD BE HEAVY THURSDAY
NIGHT AS AN AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP LIFT
MOVES OVER LOWER MICHIGAN. SNOW WILL CONTINUE ON FRIDAY AS AN UPPER
LOW MOVES ACROSS ALTHOUGH WITH LESS INTENSITY AS DEEPER LIFT AND
MOISTURE MOVES EAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1256 PM EST SAT FEB 16 2013
COMPLICATED SCENARIO FOR AVIATION INTERESTS THIS AFTERNOON AND
EVENING. LAKE EFFECT SNOW SHOWERS ARE ONGOING THIS AFTERNOON...
HOWEVER THERE A FEW WEAK WAVES MOVING THROUGH THAT ARE
COMPLICATING THE SITUATION AND ARE DISRUPTING TYPICAL BANDING.
KGRR AND KLAN SEEM TO BE NORTH AND EAST OF THE MORE SIGNIFICANT
SNOW SHOWERS...AND SHOULD REMAIN SO WITH ONLY SCATTERED SNOW
SHOWERS THIS AFTERNOON.
THE OTHER SITES ARE SEEING DECENT LAKE EFFECT AT TIMES. KMKG IS
SEEING MORE LAKE EFFECT BANDING...WHILE KAZO...KBTL...AND KJXN
SHOULD SEE THE EFFECTS OF THE WAVE THAT IS JUST WEST OF HASTINGS
AT 18Z. SOME LOWER IFR-LIFR CONDITIONS ARE EXPECTED WITH THIS
WAVE AT THOSE SITES...ESPECIALLY KBTL AND KJXN.
WE EXPECT SNOW SHOWERS TO GRADUALLY SHIFT OFFSHORE THIS EVENING
FROM NE TO SW AS A LAND BREEZE DEVELOPS AND THE FLOW GENERALLY
SHIFTS TO THE NE FOR A PERIOD OF TIME. THIS SHOULD ALLOW MOST AREA
TO CLEAR OUT. LATE TONIGHT...SNOW SHOWERS WILL COME BACK ONSHORE
NORTH OF KMKG AFTER 09Z...AND THESE WILL GRADUALLY SPREAD INLAND
SUN MORNING AND WEAKEN.
&&
.MARINE...
ISSUED AT 330 AM EST SAT FEB 16 2013
WILL KEEP MARINE HEADLINE AS IS...SCA THROUGH TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 330 AM EST SAT FEB 16 2013
COLDER AIR HAS LOCKED UP ANY FURTHER SNOW MELT. WE WILL SEE A BRIEF
WARM UP ON MONDAY WITH TEMPS REACHING AROUND 40 ALONG WITH SOME
RAIN. SINCE THE WARM UP WILL BE BRIEF AND THE RAIN SHOULD BY LESS
THAN A QUARTER INCH...NO HYDRO ISSUES ARE EXPECTED. HOWEVER A FLOOD
ADVISORY REMAINS IN EFFECT FOR HIGH WATERS ON THE PERE MARQUETTE
NEAR SCOTTVILLE.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR
MIZ050-056-064-071-072.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ065-
073.
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ037-
043.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...OSTUNO
AVIATION...NJJ
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1256 PM EST SAT FEB 16 2013
.SYNOPSIS...
ISSUED AT 330 AM EST SAT FEB 16 2013
OCCASIONAL SNOW SHOWERS WILL CONTINUE TODAY AND INTO THIS EVENING.
THE SNOW WILL BE HEAVY AT TIMES. LAKE SHORE AREAS WILL PICK UP
ANOTHER 2 TO 4 INCHES...WHILE INLAND AREAS SEE 1 TO 2 INCHES. THE
SNOW IS EXPECTED TO DIMINISH AFTER MIDNIGHT.
BY MONDAY LOW PRESSURE WILL MOVE INTO THE UPPER MIDWEST. THIS
SYSTEM WILL BRIEFLY BRING TEMPERATURES UP TO AROUND 40 BY MONDAY
AFTERNOON. A PERIOD OF RAIN IS EXPECTED MONDAY AFTERNOON...THAT
WILL TURN TO SNOW MONDAY NIGHT AND CONTINUE ON TUESDAY. MORE SNOW
LOOKS LIKELY BY THURSDAY NIGHT AND FRIDAY.
&&
.UPDATE...
ISSUED AT 900 AM EST SAT FEB 16 2013
AFTER FURTHER CONSIDERATION...WILL BE UPGRADING MASON AND OCEANA
TO A WARNING. RAP GUIDANCE SUGGESTS THAT AFTER A LULL THIS MORNING...
ANOTHER SIGNIFICANT BAND MAY EXTEND FROM THESE COUNTIES THROUGH
MUSKEGON...ALLEGAN...AND KALAMAZOO COUNTIES.
UPDATE ISSUED AT 848 AM EST SAT FEB 16 2013
HAVE RECEIVED RECENT 8-12" SNOW REPORTS FROM SEVERAL LOCATIONS IN
MASON AND OCEANA COUNTIES BENEATH AN AREA OF SATELLITE IR
TEMPERATURES THAT WERE COLDER THAN -30C BETWEEN 11-12Z. 830 AM
AWOS OBSERVATION AT HART INDICATES VISIBILITY BELOW 1/4 MILE.
SUSPECT STRONG FRONTOGENETIC FORCING HAS BEEN AT PLAY AS
TEMPERATURES AT RQB AND CAD HAD DROPPED AS MUCH AS 10 DEGREES OR
MORE OVER THE PAST FEW HOURS. PRESENT THINKING IS THAT FGEN
FORCING SHOULD DECREASE ALONG WITH MOST INTENSE SNOW THROUGH 10
AM. THIS IS SUPPORTED BY THE 16/09Z RUN OF THE HRRR...WHICH TAPERS
PRECIP AND MOVES IT INLAND THROUGH 15Z. BELIEVING WE ARE ON A
DOWNWARD TREND AFTER A PEAK IN SNOWFALL INTENSITY...WILL KEEP THE
ADVISORY GOING IN THIS AREA AND UPDATE WITH THE LATEST THINKING.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 330 AM EST SAT FEB 16 2013
A RATHER DISORGANIZED PATTERN SO FAR EARLY THIS MORNING. A SURFACE
TROUGH HAS BEEN CROSSING THE LAKE EARLY THIS MORNING AND THE WIND
PATTERN AROUND THIS TROUGH HAS BEEN DISRUPTING ANY ORGANIZED LAKE
EFFECT BANDS. THERE HAS BEEN A PERSISTENT BAND ACROSS THE NW
COUNTIES NEAR LUDINGTON AND WHITEHALL...BUT OTHER SNOW BANDS HAVE
BEEN FAIRLY TRANSITORY...KEEPING ACCUMS DOWN.
THE SURFACE TROUGH LINGERS OVER THE AREA MUCH OF TODAY...SO FEEL WE
MAY STRUGGLE TO GET PERSISTENT LES BANDS. RAP13 LOW LEVEL
CONVERGENCE FIELDS SUGGEST THE LDM BAND MAY HOLD PAT MUCH OF THE
DAY. IF THIS HOLDS TRUE...THIS BAND COULD PUT DOWN ANOTHER FOUR
INCHES OR SO. A BETTER FLAIR UP IS INDICATED TOWARD 16Z FOR THE SW
COUNTIES AND THIS IS PAINTED TO LAST THROUGH MUCH OF THE AFTERNOON.
ALSO OF INTEREST IS A SYNOPTIC CONVERGENCE BAND THAT FLAIRS UP NORTH
OF THE SURFACE TROUGH ALONG HIGHWAY 10 BY MID TO LATE AFTERNOON
TODAY. IF THIS HOLDS TRUE THERE COULD BE A BURST OF SNOW ACROSS ALL
OF THE NORTHERN COUNTIES INTO THIS EVENING.
NEEDLESS TO SAY A RATHER COMPLEX PATTERN FOR TODAY. THOUGHT ABOUT
DROPPING SOME OF THE COUNTIES IN THE ADVISORY AS THE LAKE EFFECT
DOES NOT LOOK AS ROBUST ANYMORE. HOWEVER SINCE SNOW WILL STILL
OCCUR...IT IS SORT OF HARD TO DROP HEADLINES IN THE MIDDLE OF AN
EVENT. SO WILL LEAVE THE ADVISORY AS IS...ALTHOUGH WILL HIGHLIGHT
SLIGHTLY LESS ACCUMS. ON THE OTHER HAND...INLAND AREAS COULD SEE A
BIT MORE SNOW THEN WHAT IS CURRENTLY IN THE FORECAST DUE TO THE
SYNOPTIC FEATURES. SO HAVE BUMPED UP ACCUMS A BIT INLAND...
ESPECIAL NEAR HIGHWAY 10 TO COVER THE POSSIBLE CONVERGENCE BURST
LATE TODAY INTO THIS EVENING. THE SNOW SHOULD BE DWINDLING AFTER
MIDNIGHT AS THE SYSTEM PULLS AWAY AND INVERSION LEVELS COME DOWN.
WILL CONTINUE WITH THE CHANCE POPS ON SUNDAY ALONG THE LAKE SHORE.
WINDS WILL PIVOT FROM THE NNW EARLY IN THE DAY TO SW TOWARD MID
DAY. THIS SHOULD PUSH ANY LAKE BAND INLAND...PRODUCING A BRIEF SNOW
SHOWER MAINLY WEST OF U.S. 131.
THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE MONDAY SYSTEM...
BRINGING IT IN QUICKER. HAVE INCREASED POPS TO LIKELY BY MID TO
LATE AFTERNOON. SHOULD BE WARM ENOUGH OF MOSTLY RAIN...ALTHOUGH A
MIX SHOULD FALL OVER CENTRAL LOWER.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EST SAT FEB 16 2013
ACTIVE WEATHER PATTERN NEXT WEEK WITH TWO STORMS TO WATCH. A CLIPPER
MOVES MOVES EAST MONDAY NIGHT WITH RAIN AND SNOW MIX CHANGING TO
SNOW...FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY AFTERNOON
INTO WEDNESDAY.
SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON
WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM TAKES
SHAPE ACROSS THE PLAINS AND MOVES NORTHEAST SPREADING A BAND OF SNOW
INTO LOWER MICHIGAN BY LATE THURSDAY. SNOW COULD BE HEAVY THURSDAY
NIGHT AS AN AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP LIFT
MOVES OVER LOWER MICHIGAN. SNOW WILL CONTINUE ON FRIDAY AS AN UPPER
LOW MOVES ACROSS ALTHOUGH WITH LESS INTENSITY AS DEEPER LIFT AND
MOISTURE MOVES EAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1256 PM EST SAT FEB 16 2013
COMPLICATED SCENARIO FOR AVIATION INTERESTS THIS AFTERNOON AND
EVENING. LAKE EFFECT SNOW SHOWERS ARE ONGOING THIS AFTERNOON...
HOWEVER THERE A FEW WEAK WAVES MOVING THROUGH THAT ARE
COMPLICATING THE SITUATION AND ARE DISRUPTING TYPICAL BANDING.
KGRR AND KLAN SEEM TO BE NORTH AND EAST OF THE MORE SIGNIFICANT
SNOW SHOWERS...AND SHOULD REMAIN SO WITH ONLY SCATTERED SNOW
SHOWERS THIS AFTERNOON.
THE OTHER SITES ARE SEEING DECENT LAKE EFFECT AT TIMES. KMKG IS
SEEING MORE LAKE EFFECT BANDING...WHILE KAZO...KBTL...AND KJXN
SHOULD SEE THE EFFECTS OF THE WAVE THAT IS JUST WEST OF HASTINGS
AT 18Z. SOME LOWER IFR-LIFR CONDITIONS ARE EXPECTED WITH THIS
WAVE AT THOSE SITES...ESPECIALLY KBTL AND KJXN.
WE EXPECT SNOW SHOWERS TO GRADUALLY SHIFT OFFSHORE THIS EVENING
FROM NE TO SW AS A LAND BREEZE DEVELOPS AND THE FLOW GENERALLY
SHIFTS TO THE NE FOR A PERIOD OF TIME. THIS SHOULD ALLOW MOST AREA
TO CLEAR OUT. LATE TONIGHT...SNOW SHOWERS WILL COME BACK ONSHORE
NORTH OF KMKG AFTER 09Z...AND THESE WILL GRADUALLY SPREAD INLAND
SUN MORNING AND WEAKEN.
&&
.MARINE...
ISSUED AT 330 AM EST SAT FEB 16 2013
WILL KEEP MARINE HEADLINE AS IS...SCA THROUGH TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 330 AM EST SAT FEB 16 2013
COLDER AIR HAS LOCKED UP ANY FURTHER SNOW MELT. WE WILL SEE A BRIEF
WARM UP ON MONDAY WITH TEMPS REACHING AROUND 40 ALONG WITH SOME
RAIN. SINCE THE WARM UP WILL BE BRIEF AND THE RAIN SHOULD BY LESS
THAN A QUARTER INCH...NO HYDRO ISSUES ARE EXPECTED. HOWEVER A FLOOD
ADVISORY REMAINS IN EFFECT FOR HIGH WATERS ON THE PERE MARQUETTE
NEAR SCOTTVILLE.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR
MIZ050-056-064-071-072.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ065-
073.
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ037-
043.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...OSTUNO
AVIATION...NJJ
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1159 AM CST SAT FEB 16 2013
.UPDATE...
ISSUED AT 1159 AM CST SAT FEB 16 2013
RADAR ACTIVITY IS NOW CONFINED TO AREAS EAST OF A KANW TO KBBW
LINE...WITH THE WARM FRONT CURRENTLY FROM NEAR KBIR TO KANW TO
KBBW. OBSERVATIONS ARE SHOWING VERY LIGHT SNOW OR FLURRIES FROM
THIS ACTIVITY AND AS THE FRONT CONTINUES TO MOVE EAST THIS
AFTERNOON...DO EXPECT ANY ACCUMULATING SNOW TO END IN THE NEXT FEW
HOURS WITH ONLY FLURRIES THROUGH THE REMAINDER OF THE AFTERNOON.
TEMPERATURES HAVE BEEN CLIMBING STEADILY THROUGH THE MORNING WITH
READINGS IN THE MID TO UPPER 40S ACROSS MUCH OF THE AREA BY 18Z.
THE EXCEPTION IS AREAS WHERE SNOW COVER REMAINS OVER THE WESTERN
AND NORTHERN SANDHILLS...WITH LOWER TEMPERATURES IN THOSE AREAS.
ALSO...BREEZY WINDS WILL OCCUR THROUGH THE AFTERNOON AS THE
BOUNDARY LAYER MIXES DOWN SOME OF THE STRONGER WINDS ALOFT. MAY
MIX A BIT HIGHER THAN 850MB THIS AFTERNOON...AND WITH WINDS AT
THAT LEVEL OF 25KTS TO 35KTS...WOULD EXPECT A FEW HOURS OF SOME
PRETTY BREEZY CONDITIONS THIS AFTERNOON.
.UPDATE...
MULTI MODEL BLEND OF RUC...HRRR...GEMREG...SREF...NAM...ECM
PRODUCED WARMER TEMPS TODAY AND SUNDAY AS WARRANTED BY THE KUNR
SOUNDING. NO DISCERNIBLE CHANGE OCCURRED TO THE ONGOING WEATHER
USING THE SAME BLEND. A NEW FCST IS OUT...KIML COULD REACH 60F ON
SUNDAY. OVERALL THE SNOW MOVES OUT QUICKLY THIS MORNING WITH
CLEARING TO FOLLOW JUST A RAPIDLY ALONG AND WEST OF HIGHWAY 83.
CLOUDS STAY IN LONGER EAST OF 83 AS ANOTHER BATCH OF CLOUDS MOVES
DOWN FROM THE DAKOTAS LATER THIS MORNING.
.PREV DISCUSSION... /ISSUED 413 AM CST SAT FEB 16 2013/
.UPDATE...
RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING
LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS
STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS
LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS
OVER AN OBSERVATION SITE.
THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A
SPECIAL WEATHER STATEMENT.
PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/
SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR
SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS
MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE
DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT
BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING
HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S
SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20.
LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED
PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER
STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY.
CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG
SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD.
MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD
EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE
ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW
LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE
THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS
THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT
GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F
OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL
SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING
BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW
TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE
ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN
HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL
NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR
SOUTHWEST.
ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY
NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG
UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY
NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL
BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH
A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE
HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING
PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF
25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO
SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH
EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS
LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER
TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY
TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS
INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA
FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST
AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR
PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE.
THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY
THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE
LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC
WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH
DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND
EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT
KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF
THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE
INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE.
&&
$$
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1159 AM CST SAT FEB 16 2013
LIGHT SNOW SHOWERS OR FLURRIES WILL BE CONFINED TO LOCATIONS EAST
OF A LINE FROM KANW TO KBBW THIS AFTERNOON AND WILL DIMINISH BY
EVENING AS A WARM FRONT PROGRESSES ACROSS THE AREA INTO EASTERN
NEBRASKA. SKIES HAVE CLEARED OVER MUCH OF WESTERN NEBRASKA BY
18Z...HOWEVER WITH AFTERNOON MIXING...COULD SEE SOME SCATTERED
CLOUDS NEAR 7K FEET. ALSO WITH THE MIXING OF THE BOUNDARY LAYER
EXPECTED...SHOULD SEE NORTHWEST WINDS WITH GUSTS TO 25 OR 30KTS
THROUGH THE AFTERNOON HOURS. CLEAR SKIES ARE EXPECTED
OVERNIGHT...WITH WINDS DIMINISHING AS WELL. FOR SUNDAY...A COLD
FRONT WILL MAKE ITS WAY INTO THE CENTRAL AND NORTHERN PLAINS.
WINDS WILL SHIFT TO THE SOUTHWEST BY SUNDAY MORNING AHEAD OF THE
FRONT AND INCREASE BY 18Z. THE FRONT IS NOT EXPECTED TO MOVE
THROUGH KVTN OR KLBF UNTIL SUNDAY AFTERNOON OR EVENING SO A WIND
SHIFT WILL NOT COME THROUGH THIS TIME PERIOD. MAY SEE AN INCREASE
OF CLOUDS IN ADVANCE OF THE FRONT ON SUNDAY...BUT CEILINGS WILL BE
VFR.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BROOKS
SHORT TERM...JACOBS
LONG TERM...JACOBS
AVIATION...BROOKS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
320 PM CST SAT FEB 16 2013
.SHORT TERM...
TEMPS TONIGHT A CHALLENGE ONCE AGAIN. LOW CLOUDS/FOG FROM THIS
MORNING CLEARED OFF AND A SOUTH-SOUTHEAST WIND HELPING TO WARM
THINGS UP A BIT...BUT TEMPS QUITE VARIABLE WITH TEMPS STRUGGLING
INTO THE MID TEENS IN MOST OF THE FCST AREA WHILE A FEW SPOTS IN
THE MN TREES SEEING MID 20S. AREA OF CLOUD COVER DVL-JMS REGION
REALLY BREAKING UP SOME THIS AFTN BUT IDEA IS THESE CLOUDS ASSOC
WITH 850MB WARM ADV WILL SPREAD EAST TONIGHT. UPSTREAM CANADIAN
RADAR AND OBS SHOWS SOME LIGHT SNOW BRANDON-DAUPHIN-PORTAGE MB
REGION AND DID COORD WITH WFO BIS AND SPREAD SOME FLURRIES
SOUTHEAST THIS EVENING INTO NE ND. FOR LATER TONIGHT...CLOUD BAND
MOVES MORE INTO MN FCST AREA AND RAP ISENTROPIC FCSTS INDICATE
SOME LIFT 750-850 MB REGION DEVELOPING IN BDE-BJI AREA BY 12Z SUN.
THUS KEPT LOW POP FOR -SN IN LAKE OF THE WOODS REGION AND SPREAD
MENTION OF FLURRIES A BIT MORE BACK INTO NRN VALLEY AND REST OF NW
MN. BUFKIT SOUNDINGS SHOW PTYPE ALL -SN THRU 12Z.
AS FOR TEMPS...QUITE CHALLENGING AS SHOULD SEE SOME DROP AGAIN IN
THE EAST BUT OTHERWISE FAIRLY STEADY IF NOT RISE A BIT OVERNIGHT
IN ERN ND. USED A BLEND OF MODEL GUIDANCE FOR HOURLY TEMPS.
FOR SUNDAY...MAIN ISENTROPIC LIFT HANGS OVER LAKE OF THE WOODS
REGION WITH MAJORITY OF THE FCST IN DRY SLOT AT 850 MB. SOUNDINGS
DO SHOW SOME 925 MB MOISTURE BUT LIFT IN THAT LAYER APPEARS
INSUFFICIENT TO PRODUCE ANY FZDZ WE HAD IN THE PREV FCST. THROUGH
COORD WITH ABR/MPX/BIS REMOVED FZDZ MENTION SUNDAY. PTYPES IN FAR
NW MN WHERE POPS ARE WOULD BE -SN. TEMPS SHOULD WARM ESP LATER ON
IN THE DAY AS WINDS TURN A MORE WEST AND ALLOW TEMPS TO WARM INTO
THE LOWER 30S. OTHERWISE EXPECT A STIFF SOUTH-SOUTHEAST WINDS LATE
TONIGHT THRU SUNDAY MIDDAY.
12Z GFS MODEL A BIT MORE LIKE THE OTHER MODELS NOW IN REGARDS TO
SUN NIGHT-MON SYSTEM. 00Z/06Z SAT RUNS A BIT AGGRESSIVE. SFC LOW
WILL MOVE FROM EC SASK INTO SW MB SUNDAY AFTN THEN TOWARD LAKE OF
THE WOODS REGION 06Z MON. MAIN SNOW WITH THIS LOW AND KEPT IDEA OF
2-4 INCHES IN RRT/BDE AREAS. OTHERWISE MAIN ACTION WILL WAIT WITH
COLD FRONT WHICH WILL DROP DOWN SUN LATE NIGHT INTO MONDAY
MORNING. SHOULD SEE SOME LIGHT SNOW WITH THIS...MORE SNOW
SHOWERY...ALONG WITH A PD OF STRONG WINDS MONDAY. BUFKIT SOUNDINGS
SHOW ADIABATIC TO AROUND 880 MB AT GFK/FAR MONDAY MIDDAY WHERE
WINDS OF 30-35 KTS SHOULD MIX DOWN. STRONG COLD ADV AS WELL AS
HIGH BUILDS IN AND SFC LOW STRENGTHENS TO OUR EAST. ISSUED A
SPECIAL WX STATEMENT FOR MONDAY AS WIND AND LIGHT SNOW WILL CAUSE
BLOWING SNOW AND LIKELY NASTY TRAVEL CONDITIONS.
TEMPS TO DROP WELL BLOW ZERO MONDAY NIGHT AND RECOVER ONLY
SLIGHTLY TO THE SINGLE DIGITS ABOVE AND BLO ZERO TUESDAY WITH
DIMINISHING WINDS. WIND CHILLS THOUGH EARLY TUESDAY MAY DROP TO
-30 TO -35F IN NE ND.
.LONG TERM (TUE NIGHT-SAT)...
MID LEVEL RIDGING AND SFC HIGH PRESSURE SHOULD BE OVER THE FA TO
START THE LONG TERM PERIOD. WITH THE SFC HIGH AND A COLD AIRMASS IN
PLACE TEMPS WILL STILL BE CHILLY TUE NIGHT INTO WED. FLOW WILL
TRANSITION BACK TO THE SOUTHWEST WITH ANOTHER COLORADO LOW SYSTEM
EJECTING OUT ON THU. HPC MEAN TAKES THIS LOW FROM SE COLORADO AT 12Z
THU TO NEAR CHICAGO BY 12Z FRI WHICH USES A GLOBAL MEAN. LATEST RAW
12Z MODEL GUIDANCE FROM BOTH THE ECMWF AND GFS IS FURTHER WEST WITH
THE SFC LOW. THEREFORE THERE IS STILL UNCERTAINTY WITH THE TRACK OF
THIS NEXT SYSTEM YET. AS FOR NOW WILL LEAVE HIGHER THAN GUIDANCE
PCPN CHANCES ACROSS THE SOUTHEAST FA FOR THU INTO THU NIGHT AND SEE
WHAT LATER RUNS HAVE IN STORE. MAY BE LINGERING LIGHT SNOW FROM THIS
SYSTEM ALL THE WAY INTO SAT.
&&
.AVIATION...
CLOUD COVER REMAINS THE MAIN AVIATION CHALLENGE. HAD THOUGHT SOME OF
THE CLOUDS TO THE WEST OR NORTH WOULD WORK INTO THE VALLEY DURING
THE AFTERNOON BUT THEY HAVE BEEN THINNING INSTEAD. EITHER WAY THE
HEIGHT RANGES WOULD BE IN THE VFR RANGE. SHOULD SEE STEADY SOUTH
WINDS TONIGHT BECOME GUSTY BY SUNDAY MORNING.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
RIDDLE/GODON
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
348 PM EST SAT FEB 16 2013
.SYNOPSIS...
IN THE WAKE OF A DEPARTING UPPER LEVEL TROUGH...HIGH PRESSURE
WILL BUILD OVER THE AREA ON SUNDAY. RETURN FLOW AND SOUTHERLY
WINDS WILL BRING WARMER AIR TO THE REGION MONDAY AND OVERNIGHT
AHEAD OF THE NEXT COLD FRONT THAT WILL CROSS LATE MONDAY NIGHT.
RAIN WILL OVERSPREAD THE REGION AHEAD OF THIS NEXT FRONTAL
PASSAGE.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
UPPER LEVEL TROUGH IS MOVING EAST THROUGH THE NORTHERN OHIO
VALLEY/GREAT LAKES REGION TONIGHT. THE BEST COLD PUSH IS ONGOING
RIGHT NOW AND HELPING TO CONTINUE THE CONVECTION GOING ON THIS
AFTERNOON. WITH THE LOSS OF DAYTIME INSOLATION THE SURFACE WILL
COOL OFF TONIGHT AND THERMAL DIFFERENTIAL CAUSING THE SNOW
SHOWERS WILL QUICKLY DISSIPATE THIS EARLY EVENING...EVEN AS THE
COLDEST AIR CONTINUES TO SETTLE OVER THE REGION LATE TONIGHT.
NAM AND HRRR WERE PREVIOUSLY SHOWING A WEAK AREA OF FORCING AND
LIGHT SNOW RUNNING FROM ABOUT INDIANAPOLIS AT 0Z TONIGHT TOWARDS
CINCINNATI AROUND 6Z AND THEN SOUTH OF A MAYSVILLE/VANCEBURG LINE
BY DAYBREAK. I INCLUDED SOME LIGHT SNOW IN THESE AREAS BUT THE
ACTUAL OCCURRENCE OF THIS EVENT REMAINS TO BE SEEN AND MAY NOT
MATERIALIZE.
SKY COVER IS QUITE CELLULAR LOOKING IN NATURE AND SHOULD DISSIPATE
RELATIVELY QUICKLY OUTSIDE OF CENTRAL OHIO TONIGHT...AND IN THE
INDY-CINCY-NORTHERN KY LINE PREVIOUSLY MENTIONED FOR INCREASED
SNOW POTENTIAL. THIS RELATIVE CLEARING WILL LET TEMPERATURES DROP
INTO THE TEENS WITH SOME SINGLE DIGITS POSSIBLY IN COLDER LOW-
LYING AREAS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
A BRIEF RESPITE BETWEEN SYSTEMS WILL BE FOUND SUNDAY AND WARMER
AIR WILL REALLY BEGIN TO BE USHERED IN MONDAY AFTER A MINOR DROP
OR RELATIVELY STEADY TEMPERATURES IN THE LOWER 20S SUNDAY NIGHT.
MILD AIR ON MONDAY AND OVERNIGHT WILL BE SHORT LIVED. RAIN WILL
SPREAD EAST IN THE EVENING AS THE DAYTIME SHOULD JUST SEE
INCREASING CLOUD COVER FROM WEST TO EAST. THE RAIN WILL BE
EVERYWHERE BY MIDNIGHT AND IS EXPECTED TO TAIL OFF QUICKLY WITH
THE PASSAGE OF THE FRONT...BEFORE DAYBREAK IN INDIANA. WINDS WILL
SHIFT WEST BEHIND THE FRONT AND DRIER AIR BEING USHERED IN WILL
MARK THE END OF THE RAIN. TEMPERATURES IN THE WARM SECTOR MONDAY
SHOULD RISE INTO THE UPPER 40S AND LOW 50S...WITH SOME MID 50S
POSSIBLE IN KENTUCKY.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
PERIOD BEGINS WITH A CDFNT FORECASTED TO BE PUSHING ACROSS THE
FA. EXACT PLACEMENT OF THE FRONT AT 12Z TUESDAY WILL AFFECT THE
PCPN TYPE AND POPS FOR THE FIRST FEW HOURS OF THE DAY. THE 12Z NAM
APPEARS TO BE THE QUICKEST WITH THE FRONT...PUSHING IT INTO THE
APPALACHIANS ALREADY. THE MORE GLOBAL MODELS HAVE THE FRONT
SLOWER...MAYBE AROUND I-75. TRENDED TOWARDS THE CONSENSUS...THUS
KEPT LIKELY POPS IN THE E AHEAD OF THE FNT...BUT DRIED OUT THE
POPS POST FRONTAL. WITH FROPA SO EARLY...WILL PROBABLY SEE FALLING
OR STEADY TEMPERATURES FOR TUESDAY. ALSO THREW IN A MENTION OF A
CHC OF SNOW SHOWERS FOR LATE TUE MORNING INTO TUE AFTN AS THE
MODELS ARE SHOWING CYCLONIC SFC FLOW COMBINING WITH WLY CAA AT H8.
HIGH PRESSURE BUILDS DOWN INTO THE LOWER OHIO VALLEY TUE NIGHT
INTO WED BEFORE LIFTING NE ACROSS THE FA WED NGT. THIS SHOULD
PROVIDE DRY CONDITIONS FOR THE PERIOD...WITH NRN SECTIONS SEEING
MORE CLOUDS THAN THE S TUE NGT AND WED...BEFORE MOSTLY CLEAR SKIES
PREVAIL WED NGT.
SYSTEM DIGS INTO THE SRN ROCKIES WED NGT...THEN EJECTS OUT THU
INTO THU NGT. MODELS ARE SHOWING THEIR TYPICAL SPREAD. THE CMC IS
THE QUICKEST THIS RUN IN BRINGING RETURN PCPN TO THE FA THU AFTN.
THE 12Z RUNS OF THE GFS AND ECMWF ARE SLOWER...LIMITING POPS TO
THE SW. THICKNESSES WILL BE COLD ENUF FOR SOME RAIN/SNOW AT THE
ONSET. AS THE CENTER OF THE SYSTEM LIFTS OUT THRU THE PLAINS...AN
AREA OF PCPN WILL BE PUSHED ACROSS THE FA THU NGT INTO FRI. PCPN
WILL EITHER BE SN OR RA/SN MIX UNTIL A WRMFNT GRADUALLY BRINGS IN
WARMER AIR CHANGING THE PCPN TO RA BEFORE IT ENDS ON FRIDAY. HIGH
PRESSURE THEN BUILDS IN FOR FRIDAY.
COLD AIR WILL WORK IN TUESDAY NIGHT DROPPING TEMPERATURES IN THE
TEENS AND LOWER 20S. THE COOL NLY FLOW ON WED WILL KEEP TEMPS DOWN
IN THE UPPER 20S N TO THE MID 30S NRN KY. THE CLEAR SKIES WILL
ALLOW TEMPERATURES TO DROP BACK INTO THE TEENS AND LOWER 20S
AGAIN. ONLY EXPECT HIGHS ON THU TO MAKE THE 30S AHEAD OF THE STORM
SYSTEM...BUT WITH RISING TEMPS THU NGT. HIGHS FRIDAY SHOULD MAKE
THE 40S AS THE REGION GETS WARM SECTORED.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
WIDESPREAD FLURRIES AND OCCASIONAL BRIEF HEAVY SNOW SHOWERS WILL
CONTINUE TO AFFECT THE CMH/LCK/ILN/DAY TERMINALS THROUGH ABOUT 21Z
BEFORE SHIFTING EAST OF THE AREA. EXPECT MAINLY VFR/MVFR
CONDITIONS IN THIS TIME...BUT IN THE HEAVIEST OF SNOW SHOWERS
COULD SEE IFR OR EVEN LIFR VSBYS FOR A BRIEF PERIOD OF TIME AND
CIGS AROUND 1500FT. SECONDARY SUBTLE WAVE UPSTREAM OVER WI/IL/IA
EXPECTED TO POSSIBLY BRING A MUCH SMALLER/MORE LIMITED SWATH OF
SNOW TO CVG-AREA TERMINALS AFTER SUNSET...WITH LOW CONFIDENCE ON
TIMING. WENT WITH A MIDDLE OF THE ROAD 04Z-07Z TIMEFRAME WHICH IS
A LITTLE LATER THAN RAP AND A LITTLE EARLIER THAN NAM-WRF...BUT
DON/T EXPECT OVERALL IMPACTS FROM THIS TO BE LARGE...THINKING MVFR
CONDITIONS AT WORST. CLOUDS OVERNIGHT AND ESP INTO SUNDAY MORNING
ARE PROBLEMATIC...WAS NOT EAGER TO IMPROVE MVFR/VFR BKN CIGS
OVERNIGHT DESPITE PASSAGE OF UPPER TROUGH AND DEEPER SUBSIDENCE.
THERE IS SOME LOW CLOUD UPSTREAM CAUGHT UNDERNEATH THE WEAK
SURFACE FLOW /RIDGE AXIS/ WHERE THE LOW LEVEL FLOW TURNS FROM NWLY
TO SWLY BUT SOME OF THIS IS ALSO OPEN- CELLULAR IN NATURE. IN
GENERAL DELAYED THE CLEARING FROM BKN-SCT A FEW HOURS FROM
INHERITED TAFS...THOUGH A PERIOD OF CLEARING IS POSSIBLE NEAR CVG
LATE THIS AFTN/EVE BEFORE NEXT BATCH OF MOISTURE ARRIVES.
OUTLOOK...MVFR CIGS AND VSBYS POSSIBLE MONDAY NIGHT AND EARLY
TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...FRANKS
SHORT TERM...FRANKS
LONG TERM...SITES
AVIATION...BINAU
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
143 PM EST SAT FEB 16 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH MOVING ACROSS THE GREAT LAKES WILL RESULT IN
SEASONABLY COOL TEMPERATURES AND A CHANCE OF SNOW SHOWERS TODAY.
HIGH PRESSURE WILL BUILD INTO THE AREA ON SUNDAY BEFORE A LOW
PRESSURE SYSTEM MOVES IN FROM THE WEST MONDAY NIGHT. INCREASING
SOUTHERLY FLOW AHEAD OF THE LOW WILL RESULT IN MUCH WARMER TEMPERATURES
BY MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
16.12Z KILN RAOB SAMPLED THE IMPORTANT ASPECTS OF THE COLD/SHARP
TROUGH THAT IS SHIFTING THROUGH THE AREA TODAY. WITH 500MB
HEIGHTS/TEMPS NEAR 5250M/-40C RESPECTIVELY...THIS IS AN
IMPRESSIVELY DEEP SYSTEM THAT WILL LEAD TO YET ANOTHER DAY OF
HIGHLY VARIABLE/CHANGEABLE WEATHER INCLUDING SNOW SHOWERS WITH LOW VSBYS.
THE STEEP LOW LEVEL LAPSE RATE ENVIRONMENT IS ALREADY IN PLACE PER
THE 12Z SOUNDING /850MB TEMPS TO -14C/ AND THESE SHOULD FALL
FURTHER TOWARD -17C INTO THIS EVENING...AND WITH THE TROUGH AXIS
STILL TO THE WEST...TROPOSPHERIC COOLING /DECREASING STABILITY/
WILL CONTINUE TO SUPPORT AN INCREASE IN CLOUDS AND EVENTUALLY SNOW
SHOWER DEVELOPMENT.
THERE GENERALLY IS STRONG AGREEMENT FROM THE CONVECTION-ALLOWING
SUITE OF GUIDANCE INCLUDING HRRR/SPC-WRF/NSSL-WRF THAT AREA OF
SNOW SHOWERS NOW DEVELOPING TO OUR NORTHWEST/WEST WILL INCREASE IN
COVERAGE/INTENSITY AS IT MOVES THROUGH OUR AREA LATE THIS
MORNING/AFTN...WITH HIGHEST COVERAGE NORTH OF I-70...AND LEAST
COVERAGE OVER NRN KY AND SERN IN. HAVE INCREASED SNOW CHANCES MOST
AREAS FROM 16Z-21Z AND INDICATED ACCUMS UP TO AN INCH IN THE
NORTH...THOUGH ACTUAL ACCUMS WILL BE HIGHLY DEPENDENT ON THE VERY
SMALL SCALE CONVECTIVE SNOW BURSTS. RAP/NAM FCST BUFR SOUNDINGS
/C25...KCMH...AND KILN/ ALL SUGGEST THAT DESPITE THE SHALLOW
NATURE OF MOISTURE/CONVECTIVE SNOW SHOWERS...THAT SUPERSATURATION
WITH RESPECT TO ICE IS LIKELY TO EXIST IN THE MOST INTENSE SQUALLS
IN -12C TO -18C REGION OF SOUNDING WHICH WOULD LEAD TO LARGE
DENDRITIC FLAKES AND HEAVY RATES /LOW VSBYS/ EVEN IN SHORT DURATION.
ACCUMULATIONS WON/T BE THE IMPACT THOUGH...IT WILL BE RAPID
REDUCTIONS IN VSBYS TO BELOW 1/2SM IN THE HEAVIEST SQUALLS...AND
WITH A VERY COLD START THIS MORNING ROAD TEMPS MAY NOT BE AS
RECEPTIVE TO MELTING...ESPECIALLY WITH WINDS COMING UP A BIT OUT
OF THE NW THIS AFTERNOON AND TEMPS REMAINING IN THE 20S. SO THE
AMBIENT SETUP SEEMS TO SUPPORT A HIGHER THAN NORMAL THREAT OF
RAPIDLY CHANGING ROAD CONDITIONS AND VISIBILITIES THAT MAY LEAD TO
MORE SIGNIFICANT IMPACTS ON OUR INTERSTATE HIGHWAY SYSTEM WITHIN
THESE INTENSE SNOW BURSTS. WILL BE AGGRESSIVE WITH SPECIAL WEATHER
STATEMENTS AND HWO WORDING AS THE SNOW SHOWERS DEVELOP LATER THIS MORNING/AFTN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
THE UPPER LEVEL TROUGH AXIS WILL BEGIN TO SHIFT EAST OF THE AREA
BY TONIGHT WITH MID/UPPER LEVEL RIDGING SLIDING OVERHEAD SUNDAY
NIGHT INTO MONDAY. THIS WILL ALLOW FOR DRYING CONDITIONS AND
DECREASING CLOUDS BY SUNDAY. HOWEVER...WE DO NOT REALLY GET INTO
RETURN FLOW UNTIL SUNDAY NIGHT SO EXPECT SUNDAY TO REMAIN ON THE
COOLER SIDE WITH HIGHS ONLY IN THE UPPER 20S TO LOWER 30S.
WE COULD HAVE SOME EARLY LOWS SUNDAY EVENING WITH TEMPERATURES
THEN STEADYING OFF OR EVEN RISING A LITTLE LATE AS LOW LEVEL SOUTHERLY
FLOW BEGINS TO PICK UP AND WE GET SOME INCREASING CLOUDS.
INCREASING SOUTHWESTERLY LOW LEVEL FLOW THROUGH THE DAY ON MONDAY
WILL LEAD TO GOOD WAA AND SOME BREEZY CONDITIONS. THIS SHOULD
PUSH TEMPERATURES WELL ABOVE NORMAL WITH HIGHS ON MONDAY INTO THE
UPPER 40S TO LOWER/MID 50S. STRENGTHENING ISENTROPIC LIFT THROUGH
THE DAY WILL LIKELY ALLOW FOR SOME SHOWERS TO DEVELOP THROUGH MID
TO LATE AFTERNOON...ESPECIALLY ACROSS THE WEST.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A COLD FRONT WILL BEGIN TO WORK INTO THE AREA OVERNIGHT MONDAY
NIGHT AND MOVE EAST OF THE REGION TUESDAY MORNING. THIS FEATURE
WILL ALLOW FOR COLDER AIR TO WORK INTO THE FA AND RAIN WILL BEGIN
TO MIX AND THEN CHANGE OVER TO SNOW OVERNIGHT MONDAY NIGHT INTO
TUESDAY. DUE TO THE FRONTAL PASSAGE TEMPERATURES WILL STRUGGLE TO
RISE ON TUESDAY AND WILL ACTUALLY FALL SLOWLY THROUGH MOST OF THE
DAY. SNOW WILL COME TO AN END TUESDAY AFTERNOON AND HIGH PRESSURE
WILL WORK INTO THE FA. WITH MOSTLY CLEAR TO PARTLY CLOUDY SKIES
TUESDAY NIGHT AND WEDNESDAY NIGHT TEMPERATURES WILL DROP DOWN INTO
THE TEENS TO THE 20S FOR LOWS.
THE NEXT STORM SYSTEM WILL BEGIN TO BRING PRECIPITATION INTO THE FA
THURSDAY AFTERNOON WITH MORE WIDESPREAD PRECIPITATION ACROSS THE FA
THURSDAY NIGHT. PRECIPITATION WILL BEGIN TO TAPER OFF ACROSS THE FA
ON FRIDAY. PRECIPITATION WILL BE A MIX OF RAIN AND SNOW WITH THIS
SYSTEM.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
WIDESPREAD FLURRIES AND OCCASIONAL BRIEF HEAVY SNOW SHOWERS WILL
CONTINUE TO AFFECT THE CMH/LCK/ILN/DAY TERMINALS THROUGH ABOUT 21Z
BEFORE SHIFTING EAST OF THE AREA. EXPECT MAINLY VFR/MVFR
CONDITIONS IN THIS TIME...BUT IN THE HEAVIEST OF SNOW SHOWERS
COULD SEE IFR OR EVEN LIFR VSBYS FOR A BRIEF PERIOD OF TIME AND
CIGS AROUND 1500FT. SECONDARY SUBTLE WAVE UPSTREAM OVER WI/IL/IA
EXPECTED TO POSSIBLY BRING A MUCH SMALLER/MORE LIMITED SWATH OF
SNOW TO CVG-AREA TERMINALS AFTER SUNSET...WITH LOW CONFIDENCE ON
TIMING. WENT WITH A MIDDLE OF THE ROAD 04Z-07Z TIMEFRAME WHICH IS
A LITTLE LATER THAN RAP AND A LITTLE EARLIER THAN NAM-WRF...BUT
DON/T EXPECT OVERALL IMPACTS FROM THIS TO BE LARGE...THINKING MVFR
CONDITIONS AT WORST. CLOUDS OVERNIGHT AND ESP INTO SUNDAY MORNING
ARE PROBLEMATIC...WAS NOT EAGER TO IMPROVE MVFR/VFR BKN CIGS
OVERNIGHT DESPITE PASSAGE OF UPPER TROUGH AND DEEPER SUBSIDENCE.
THERE IS SOME LOW CLOUD UPSTREAM CAUGHT UNDERNEATH THE WEAK SURFACE
FLOW /RIDGE AXIS/ WHERE THE LOW LEVEL FLOW TURNS FROM NWLY TO SWLY BUT
SOME OF THIS IS ALSO OPEN- CELLULAR IN NATURE. IN GENERAL DELAYED
THE CLEARING FROM BKN-SCT A FEW HOURS FROM INHERITED TAFS...THOUGH
A PERIOD OF CLEARING IS POSSIBLE NEAR CVG LATE THIS AFTN/EVE
BEFORE NEXT BATCH OF MOISTURE ARRIVES.
OUTLOOK...MVFR CIGS AND VSBYS POSSIBLE MONDAY NIGHT AND EARLY
TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...JGL
NEAR TERM...BINAU
SHORT TERM...JGL
LONG TERM...NOVAK
AVIATION...BINAU
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...VISIT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
327 PM CST SAT FEB 16 2013
.SHORT TERM...THROUGH TUESDAY NIGHT
326 PM CST SAT FEB 16 2013
MUCH OF THE TIME TODAY WAS SPENT WORKING ON MONDAY INTO TUESDAY.
IMPACTS LOOK TO BE MINIMAL AS MAIN PRECIPITATION REGION LOOKS TO
ADVECT IN JUST EAST OF THE FORECAST AREA.
CLOUDS HAVE BEEN A TOUGH FORECAST AS OF LATE...AND TONIGHT THEY
COULD HAVE A HUGE IMPACT ON LOW TEMPERATURES. CURRENT GOES
SATELLITE IMAGERY SHOWING CLOUDS EXPANDING IN WRN MN WEST OF THE
SURFACE RIDGE AXIS FROM KINL TO KALO. MAINLY CUMULUS FIELDS
ARE AFFECTING THE FORECAST AREA WITH THOSE EXPECTED TO DISSIPATE
BY LATE AFTERNOON. SURFACE OBSERVATIONS SHOWING A STATIONARY FRONT
LOCATED FROM ABOUT KFSD-KDSM WITH WARM AIR TO THE SOUTHWEST AND
CONVERGENT FLOW INTO NE IA.
GOES WATER VAPOR SHOWING THE MONDAY S/WV WELL NOW COMING ONTO THE
WEST COAST WITH THE NRN ENERGY OVER BRITISH COLUMBIA AND THE
16.19Z RAP INDICATING A TROPOPAUSE FOLD TO 400MB INTO THE OR
COAST REPRESENTING THE SRN ENERGY THAT IS FORECAST TO DIG INTO THE
CENTRAL U.S. KUIL WASHINGTON RAOB HAD A 150M/12HR HEIGHT FALL THIS
MORNING AHEAD OF THIS POTENT SHORTWAVE TROUGH.
HAVE LOWERED THE LOW TONIGHT ACROSS CENTRAL WI AS THE SURFACE
RIDGE WILL BE RIGHT OVERHEAD MOST OF THE NIGHT AND CLOUDS ARE
FORECAST TO REMAIN MINIMAL. HAVE DROPPED LOWS 5-7F THERE TONIGHT
FROM PREVIOUS FORECAST. CLOUDS ARE TOUGH THOUGH AND AM THINKING
TWO AREAS COULD DEVELOP STRATUS...CURRENT HEAVY CUMULUS AREA OVER
NRN WI AND CONVERGENT BOUNDARY ACROSS IA. THE NRN WI AREA COULD
EXPAND OVER NRN FORECAST AREA LATE AND CLOUDS WILL ALSO SPREAD IN
FROM THE SW. THUS...LOW CONFIDENCE IN FORECAST CLOUDS AND LOWS
TONIGHT...BUT FORECASTING THE CENTRAL FORECAST AREA TO REMAIN
MOSTLY CLEAR.
WARM ADVECTION TO KICK IN SUNDAY AND PEAK SUNDAY NIGHT WITH
WARMING OCCURRING INTO MONDAY WEATHER SYSTEM. 16.12Z MODEL
CONSENSUS IS TO STILL DEVELOP THE NRN CYCLONE THE MOST...NORTH OF
THE GREAT LAKES...WITH THE SRN ENERGY CAUSING WEAK CYCLOGENESIS
ALONG THE FRONTAL BOUNDARY AS IT PASSES TO THE SE OF THE FORECAST
AREA. SOME SPREAD STILL REMAINS IN THE GUIDANCE. THE 16.12Z NAM
REMAINS CONSISTENT WITH IT/S PREVIOUS RUNS OF THE DRY OUTLIER. THE
16.12Z CANADIAN GLOBAL GEM STILL INSISTS ON A WET 0.30 INCHES
AREA-WIDE WITH THIS SYSTEM /AND HIGHS IN THE 40S/. STILL PREFER THE
CONSISTENT ECMWF/GFS RUNS ON THE OUTCOME FOR THIS SYSTEM. IT
APPEARS THE MAIN MOISTURE AXIS WILL ONLY GRAZE THE ERN FORECAST
AREA FROM CENTRAL WI TO SWRN WI...A STEP EAST FROM PREVIOUS MODEL
RUNS. THIS SAME AREA WILL SEE THE DEEPEST SURFACE-BASED SATURATION
COME IN MONDAY MORNING /KOVS 0-2 KM/...WITH THE LAYER MORE SHALLOW
FURTHER TO THE NW /KEAU 1KM/. NW OF THE SURFACE WAVE...WOULD THINK
A BIT OF ENHANCEMENT IN THE DEFORMATION WILL OCCUR AND HAVE KEPT
HIGHEST PRECIPITATION CHANCES IN THAT SWRN-CENTRAL WI
AREA...TAPERING LOWER TO THE NORTHWEST.
IT APPEARS DEEP SATURATION TO COLDER THAN -10C TO GET ICE GROWTH WILL
BE TROUBLESOME/SPOTTY OR JUST PLAIN HARD TO FORECAST WITH THIS
SYSTEM. THE Q-G FORCING IS MODERATE ALOFT AND WEAKER IN THE LOW
LEVELS PROVIDING OVERALL A WEAK BUT PRESENT LIFT SIGNAL. BUT
REVIEWING MODEL SOUNDINGS FROM THE 16.09Z SREF AND 16.12Z NAM/GFS
THERE IS CONSISTENT STRUGGLES WITH SATURATION NOTED...AND THUS
HAVE GONE WITH A MAJORITY OF LIQUID IN THE FORECAST UNTIL THE COLD
FRONT MOVES IN LATER MONDAY WITH VERY STRONG COLD ADVECTION TO DRIVE
THE ICE PROCESS AND SNOW CONVERSION. THIS SATURATION STRUGGLE AWAY
FROM THE SURFACE WAVE IS ALSO WHY PRECIPITATION CHANCES ARENT
HIGHER FOR THIS FORECAST.
MONDAY MORNING WILL SEE THE MOISTURE INCREASE AND SURFACE TEMPERATURES
WARMING TO NEAR OR ABOVE FREEZING IN THE AFTERNOON. THIS WILL
CAUSE A FZDZ POSSIBILITY MAINLY IN THE MORNING IF THE LAYER CAN
PRECIPITATE...PROBABLY VERY LIGHT AMOUNTS AROUND 0.01-0.02 INCHES
TO PROVIDE A LIGHT GLAZE AFTER COMMUTE TIME. MANY AREAS SOUTH OF
I-90 WILL WARM TO ABOVE FREEZING BY MID-DAY...ESPECIALLY CLOSE TO
THE MOIST AXIS SO IMPACTS WOULD BE MINIMAL THERE...OR AT LEAST
SHORT LIVED. HAVE KEPT FZDZ STILL POSSIBLE FOR POINTS WITH AIR
TEMPERATURES OF 35F OR COLDER AS ROADS MAY STILL BE SLOWER TO
RECOVER TO ABOVE FREEZING.
THE NORTHERN AND WESTERN AREAS COULD SEE FZDZ PERIODICALLY MONDAY
THROUGH THE DAY...POSSIBLE MIXING WITH SNOW AS SATURATION OCCURS
IN A PATCHY WAY. THE COLD FRONT WILL SWEEP IN WITH VERY STRONG
COLD ADVECTION CONVERTING ALL LIGHT LIQUID PRECIPITATION TO SNOW.
WITH THE COLD ADVECTION STRONG...LAPSE RATES IN THE LOWEST 1 KM
ARE QUITE STEEP AND WILL PROMOTE WIND GUSTS IN THE 25 TO 35 MPH
RANGE LATE MONDAY AND OVERNIGHT. HAVE INCREASED THE WINDS WITH
THIS FORECAST BASED ON 16.12Z NAM/GFS BLEND.
OVERALL...COMFORT REMAINS LOW ON THIS SYSTEM /I HAVE MORE
CONFIDENCE IN THE THU-FRI SNOW/ BUT MY FEELING IS THAT THE IMPACTS
WILL BE MINOR. DO NOT FEEL A NEED FOR A HEADLINE ON THIS SYSTEM AS
THE LIQUID AMOUNTS LOOK TO BE PRETTY LIGHT. IN THE DEFORMATION
AREA TEMPERATURES WOULD BE WARMEST AND MAINLY RAIN WOULD FALL. BUT
THERE ARE SOME HINTS THAT UP TO A TENTH OF PRECIPITATION COULD
FALL MONDAY AWAY FROM THE MOISTURE AXIS /KEAU SREF MEAN GIVES 0.07
OF FZDZ/ SO IT IS STILL A SYSTEM TO WATCH.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
326 PM CST SAT FEB 16 2013
THE FOCUS REMAINS ON THE INCREASINGLY ADVERTISED LATE WEEK SYSTEM
AND THE DEGREE OF IMPACT IT WILL HAVE ON THE UPPER MIDWEST. LEADING
UP TO THAT FEATURE...WEDNESDAY LOOKS TO BE A TRANSITION DAY WITH
MORNING COLD ADVECTION AS A SURFACE HIGH AND UPPER LEVEL RIDGE AXIS
REMAINS TO THE WEST OF THE FORECAST AREA. A COLD DAY ON TAP AS
MORNING LOWS IN THE SINGLE DIGITS BELOW/ABOVE ZERO LOOK TO RISE INTO
ONLY THE TEENS. THE RIDGE IS THEN EXPECTED TO BUILD ACROSS BY
WEDNESDAY NIGHT...LEADING TO RETURN SOUTHERLY FLOW. A WESTERN CONUS
TROUGH THEN DIGS AND MOVES EAST...EJECTING THE MAIN SHORTWAVE
TROUGH OUT OF THE COLORADO ROCKIES BY 12Z THURSDAY. SURFACE LOW
DEEPENS RAPIDLY ACROSS THE CENTRAL PLAINS THURSDAY...LIFTING
TOWARD THE AREA.
THE 16.12Z GFS ENSEMBLE REMAINS CLOSELY PACKED WITH A LOW TRACK
ALONG A KANSAS CITY TO NORTHERN ILLINOIS LINE THURSDAY NIGHT INTO
FRIDAY AFTERNOON. THE 16.12Z ECMWF TOOK A STEP NORTHWEST WITH ITS
SURFACE LOW TRACK AND THE 16.12Z GEM AND FIM REMAIN THE SOUTHERLY
OUTLIERS. THE GFS SEEMS TO BE A GOOD COMPROMISE. EARLIER TIMING
ISSUES APPEAR TO BE RESOLVED FOR NOW. YESTERDAY/S CONCERNS ABOUT THE
FILLING UPPER LEVEL TROUGH / SURFACE LOW AND ITS IMPACT WERE MUTED
SLIGHTLY SINCE THE 16.12Z GFS...ECMWF AND FIM CAME IN A BIT
STRONGER. HOWEVER...500 MB HEIGHT STANDARDIZED ANOMALIES STILL RISE
FROM -3.5 ACROSS THE CENTRAL PLAINS...TO AROUND -0.5 BY 12Z FRIDAY
WHICH SUGGESTS A WEAKENING TREND AND THE SYSTEM NOT NEARLY AS WOUND
UP AS IT MAY BE IN THE CENTRAL PLAINS.
PRECIPITATION WOULD OVERSPREAD THE AREA DURING THE AFTERNOON
THURSDAY...WITH THE MAIN WARM ADVECTIVE WING SWINGING THROUGH
THURSDAY NIGHT AND OVERNIGHT FRIDAY. THIS WOULD BE WHEN THE HIGHEST
SNOW RATES OCCUR. AS THE SURFACE LOW THEN MOVES NEARBY...WRAP AROUND
/ DEFORMATION BANDING SNOW WOULD LINGER THROUGHOUT FRIDAY. SOUNDINGS
STILL POINT TO AN ALL SNOW EVENT WITH THE WARMEST AIR REMAINING
SOUTH OF THE AREA.
THE MODEL CONSISTENCY AND RUN-TO-RUN SIMILARITIES REMAIN VERY ABOVE
AVERAGE AND REMARKABLE FOR IT STILL BEING 6 DAYS OUT. GIVEN THE
FEATURE IS CURRENTLY OVER THE DATA SPARSE NORTHERN PACIFIC...THERE
CERTAINLY WILL BE FINE-TUNE DETAILS TO ESTABLISH. PRECIPITATION
AMOUNTS TOOK A STEP UP IN THE LATEST ROUND OF GUIDANCE THOUGH STILL
REMAIN BETWEEN 0.7 TO 1.0 INCH. CONFIDENCE CONTINUES TO GROW IN A
WARNING LEVEL EVENT WITH WIDESPREAD 6 TO 10 INCH AMOUNTS IF THE
CURRENT AND PAST SOLUTIONS INDEED VERIFY. THE BIG PICTURE IS THAT
THOSE WITH INTERESTS AND TRAVEL CONCERNS LATE NEXT WEEK SHOULD
CONTINUE TO MONITOR AND FOR NOW...HAVE CONTINUED TO PUSH HIGHER
PRECIPITATION CHANCES THURSDAY NIGHT...AND TRENDED FRIDAY HIGHER AS
WELL SINCE IF THE SYSTEM DOES SLOW DOWN / FILL IN THEN THERE WOULD
CERTAINLY BE LINGERING DEFORMATION BANDING SNOW ACROSS MUCH OF THE
AREA. THE PROLONGED DURATION / THURSDAY NIGHT THROUGH LATE FRIDAY
NIGHT / COULD PRESENT SOME CHALLENGES FOR TRAVELERS AND ROAD CREWS
AS WELL.
&&
.AVIATION...THROUGH 18Z SUNDAY
1128 AM CST SAT FEB 16 2013
THE MAIN CONCERNS ARE IN THE NEAR TERM WITH SKY CONDITIONS AND
SOME LIGHT SNOW POSSIBLY GETTING INTO RST. THIS BAND OF LIGHT SNOW
HAS BEEN JUST TO THE WEST OF RST ALL MORNING AND HAS BROUGHT
VISIBILITY DOWN TO IFR...MAINLY AT 1-2SM. THE CLOUDS DO APPEAR TO
BE DIMINISHING IN COVERAGE AND THAT SHOULD BE THE TREND THROUGH
THE AFTERNOON HOURS. FURTHER EAST AT LSE..MAINLY LOOKING AT A LOW
END VFR BKN CLOUD DECK AT 3500-4500FT THROUGH THE AFTERNOON BEFORE
SUBSIDENCE KICKS IN AND HELPS CLEAR THE CLOUDS LATER THIS
AFTERNOON ON INTO THE EVENING. WINDS WILL REMAIN LIGHT THROUGH THE
NIGHT AS A RIDGE AXIS OF HIGH PRESSURE MOVES THROUGH BUT AFTER IT
PASSES BY TOMORROW MORNING...THE PRESSURE GRADIENT WILL TIGHTEN UP
WITH SOUTHEAST WINDS INCREASING TO 10-20KTS BY LATE MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
151 PM CST SAT FEB 16 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...TAYLOR
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
234 PM CST SAT FEB 16 2013
.SYNOPSIS...
ISSUED AT 223 PM CST SAT FEB 16 2013
MODERATING TEMPS WITH SOME LIGHT TO MODERATE PRECIPITATION MONDAY
NIGHT AND TUESDAY. STILL PLENTY OF QUESTIONS ABOUT THE NEXT SYSTEM
EXPECTED TO ARRIVE LATE IN THE WEEK.
UPR FLOW ACRS NOAM WL START OUT WITH A BROAD RIDGE OVER THE ERN
PAC/WRN NOAM...ALBEIT WITH STG SHRTWV RIGHT IN THE MIDDLE OF THE
RIDGE POSN. A DEEP TROF WAS OVER ERN NOAM...WITH RIDGING OVER THE
WRN ATL. THE SHRTWV NOW IN THE WRN RIDGE POSN AND ITS SUCCESSOR WL
BOTH DIG PROGRESSIVELY FARTHER W...EVENTUALLY PULLING THE MEAN
TROF POSN BACK INTO THE WESTERN CONUS BY MID-WK. MEANWHILE...THE
DOWNSTREAM PATTERN OVER THE ATL WL BREAK DOWN INTO A COMPLEX
BLOCKING REGIME. THE BLOCKING WL EVOLVE WWD WITH TIME...
RESULTING IN A SPLIT FLOW ACRS MUCH OF THE CONUS BY NEXT WEEKEND.
THE TWO MAJOR SHRTWVS WORKING ACRS THE CONUS DURING THE PERIOD WL
BOTH SUPPORT STG CYCLONES. THE CHANGING UPR PATTERN AND PASSAGE OF
THE CYCLONES WL TAKE TEMPS ON A ROLLERCOASTER RIDE DURING THE
PERIOD. THEY/LL START OUT COLD...QUICKLY WARM EARLY IN THE WEEK...
DROP BACK TO BLO NORMAL MID-WEEK...THEN SETTLE BACK CLOSER TO
NORMAL AS THE FLOW SETTLES INTO SPLIT REGIME. GIVEN THE 2 SIG
SYSTEMS LIKELY TO IMPACT THE AREA...PCPN AMNTS WL PROBABLY END UP
AOA NORMAL.
&&
.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 223 PM CST SAT FEB 16 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE RIDGE STRETCHING FROM TEXAS TO ONTARIO THIS AFTERNOON.
STEEPENING LOW LEVEL LAPSE RATES AND FLOW OFF SUPERIOR CONTRIBUTED
TO A WIDESPREAD DIURNAL CU FIELD...WHICH SPREAD SOUTH ACROSS MUCH
OF THE CWA BY EARLY THIS AFTERNOON. LAKE EFFECT SNOW SHOWERS
REMAINED CONFINED TO NORTHERN VILAS COUNTY AND POINTS NORTH AND
VSBYS IN THIS AREA SUGGEST ONLY MINOR ACCUMS AT BEST. PRETTY QUIET
UPSTREAM AS WELL. FGEN INDUCED BAND OF CLOUDS AND LIGHT SNOW OVER
THE PLAINS IS SLIDING SE WHILE SKY CONDITIONS ARE CLEARING OVER
MINNESOTA. CLOUD TRENDS AND TEMPS ARE THE MAIN FORECAST CONCERNS
IN THE SHORT TERM.
TONIGHT...SURFACE HIGH PRESSURE TO MOVE ACROSS THE REGION AND
THIS SHOULD RESULT IN LOW LEVEL FLOW BECOMING LIGHT THIS EVENING.
ANTICIPATING STRATO-CU TO RAPIDLY DIMINISH WITH LOSS OF DAYTIME
HEATING EARLY THIS EVENING...EXCEPT OVER NORTH-CENTRAL WISCONSIN
WHERE IT SHOULD TAKE A FEW HOURS LONGER. AS A RESULT...EXPECT SKY
CONDITIONS TO BECOME CLEAR TO MOSTLY CLEAR ACROSS THE REGION BY
LATE THIS EVENING. STRATUS UPSTREAM THIS MORNING BENEATH THE RIDGE
AXIS SEEMED ALIGNED WITH A LOW LEVEL THERMAL GRADIENT. THIS
GRADIENT DOES NOT MOVE MUCH TONIGHT...SO AM NOT EXPECTING CLOUDS
TO REFORM BENEATH THE SURFACE HIGH. TEMPS LAST NIGHT FELL INTO THE
TEENS BELOW ZERO OVER N-C WISCONSIN. SHOULD HAVE LIGHTER WINDS IN
THE BOUNDARY LAYER AND THE PWAT MINIMUM OVERHEAD...SO HAVE DROPPED
TEMPS FROM THE PREVIOUS FORECAST.
SUNDAY...HIGH PRESSURE MOVES EAST OF THE REGION AND RETURN FLOW
WILL PUSH A WARM FRONT INTO THE NORTHERN MISSISSIPPI VALLEY BY THE
AFTERNOON. THOUGH MID AND HIGH CLOUDS WILL BE INCREASING THROUGH
THE DAY...DEEPER MOISTURE WILL STAY WELL OFF TO THE NORTHWEST OVER
NORTHERN MINNESOTA AND SOUTH-CENTRAL CANADA. HIGHS WILL BE
CONSIDERABLY WARMER THAN TODAYS READINGS...AND MOSTLY RANGE FROM
THE LOWER TO MIDDLE 20S.
.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 223 PM CST SAT FEB 16 2013
WAA ON THE BACK SIDE OF DEPARTING RIDGE WL KICK INTO HIGH GEAR
SUN NGT. THE STRONGEST ISENT LIFT AND BEST CHC AT SATURATION WL BE
ACRS THE N. WENT WITH CHC POPS THERE...AND KEPT THE S DRY. EXPECT
EVENING MINS THEN RISING TEMPS.
COMPLEX STORM SYSTEM DRIVEN BY PHASING SHRTWVS WL BE ORGANIZING
AS IT CROSSES THE AREA MON...THEN DEEPEN JUST OFF TO OUR E MON NGT
INTO TUE. RAISED POPS AS FORCING LOOKS FAIRLY STG. BUT MOISTURE WL
BE LIMITED...ESP INITIALLY. THAT WL PROBABLY RESULT IN ANOTHER
EVENT WITH MESSY MIX OF SN/DZ/FZDZ DEPENDING ON WHETHER SUFFICIENT
MID-LVL MOISTURE IS PRESENT AT ANY TIME TO SEED THE LOWER CLDS FM
ABV. MODEL FCST SOUNDINGS SUGGEST LOWER-LEVELS OVER E-C WI COULD
BRIEFLY BE WARM ENOUGH FOR JUST RAIN MON AFTN EVEN IF MOISTURE IS
DEEP AT THAT TIME. WENT WITH MAINLY SN/FZDZ ACRS THE NW AND RA/SN
IN THE SE ON MON. E-C WI COULD CERTAINLY SEE DZ RATHER THAN
RAIN... BUT WANTED TO AVOID HAVING TOO MANY PCPN TYPES IN THE
FCST.
PCPN SHOULD CHG TO SNOW MON NGT...WITH SHSN ON THE BACK SIDE OF
THE SYSTEM CONTG INTO TUE. UPPED POPS AS UPR TROF WL BE SHARPENING
RIGHT ACRS THE AREA DURING THAT TIME. THINKING RIGHT NOW IS THAT
THIS WL BE A 1-3 INCH EVENT...WITH THE HIGHER TOTALS IN THE NE.
LAKE-EFFECT OFF LAKE SUPERIOR COULD BOOST TOTALS EVEN FURTHER OVER
THE SNOWBELT...THOUGH THAT DEPENDS ON EXACT TRAJECTORIES SO WON/T
GET TOO SPECIFIC WITH THAT YET.
A BREAK FM THE SIG PCPN THEN EXPECTED WED INTO THU AS UPR RIDGE
SHARPENS ACRS THE AREA. STG...COLD...VERY DRY LOW-LEVEL
ANTICYCLONE WL BE RIDGING SWD INTO THE RGN FM THE HUDSON BAY AREA.
LOW-LEVEL WINDS WL VEER ARND TO THE E...AND ALTHOUGH THE UPSTREAM
AIR WL BE VERY DRY AND INVERSION HEIGHTS WL BE LOW...WL PROBABLY
GET SOME LAKE FLURRIES INTO E-C WI.
STILL A LOT OF QUESTIONS ABOUT THE SYSTEM HEADING INTO THE AREA
DURING THE LATTER PART OF THE WEEK. DON/T LIKE THAT THE SYSTEM WL
BE DRIVING INTO A DOWNSTREAM BLOCK AND HAVE VERY DRY AIR FEEDING
INTO IT FM THE E AT LOW-LEVELS. THAT/S A CLASSIC LATE WINTER/EARLY
SPRING FCST PROBLEM HERE...AND IT TYPICALLY RESULTS IN A CONSTANT
DELAYING OF THE ONSET OF PCPN...AND OFTEN A REDUCTION IN PCPN
TOTALS. ON THE OTHER HAND...IF SYSTEM CAN GET PCPN INTO THE
AREA...DOWNSTREAM BLOCKING WL CAUSE IT TO SLOW TO A CRAWL...AND
RESULT IN A LONG-DURATION EVENT.
FEELING RIGHT NOW IS THAT THIS IS A SYSTEM THAT WL HAVE IT/S
GREATEST IMPACT OUT IN THE PLAINS. MAX SNOWS WL PROBABLY END UP IN
THE SW PART OF THE FCST AREA...AND THEY WILL PROBABLY BE
CONSIDERABLY LESS THAN WHAT FALLS TO OUR SW. AT THIS POINT...WAS
CONTENT WITH INITIALIZATION GRIDS THAT NEVER WENT BEYOND LIKELY
POPS. CERTAINLY PLENTY OF TIME FOR LATER SHIFTS TO ADJUST FCST.
WL CONT TO MENTION SYSTEM IN THE HWO...BUT DON/T PLAN ON PLAYING
THIS UP AS A BIG STORM.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1132 AM CST SAT FEB 16 2013
AS NORTH FLOW CONTINUES OFF LAKE SUPERIOR...CONDITIONS TO BECOME
SCT TO BKN THIS AFTERNOON...HIGHER PROBABILITIES OVER NORTH-
CENTRAL AND NORTHEAST WISCONSIN THAN FOR CENTRAL WISCONSIN. MVFR
CIGS WILL LIKELY IMPACT RHI AND POSSIBLY AUW/CWA THIS
AFTERNOON...BUT SNOW SHOWERS SHOULD REMAIN NORTH OF THE
AIRPORTS...FROM VILAS COUNTY TOWARDS LAKE SUPERIOR. HIGH PRESSURE
OVER THE AREA TONIGHT WILL HELP SKIES CLEAR AND WINDS BECOME LIGHT
AND VARIABLE. MID AND HIGH CLOUDS WILL BE ON THE INCREASE ON
SUNDAY AHEAD OF AN APPROACHING WARM FRONT...BUT ANY THREAT OF
PRECIP TO HOLD OFF UNTIL SUNDAY NIGHT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......SKOWRONSKI
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1128 AM CST SAT FEB 16 2013
.SHORT TERM...THIS MORNING AND AFTERNOON
1003 AM CST SAT FEB 16 2013
CURRENTLY TRACKING A BAND OF LIGHT SNOW MOVING ACROSS SOUTHEAST
MINNESOTA AND NORTHEAST IOWA WHICH HAS DROPPED VISIBILITY DOWN TO
LESS THAN A MILE AT TIMES. SOME OF THAT MAY BE DUE TO SOME FOG
BEING REPORTED IN CENTRAL MINNESOTA...BUT MOST OF THE VISIBILITY
REDUCTIONS SHOULD BE DUE TO THE SNOW FALLING. AUSTIN CITY POLICE
REPORTED THAT THERE WERE LARGE SNOW FLAKES COMING DOWN AROUND 9AM
AND THAT SOME MINOR ACCUMULATIONS WERE BEGINNING. THE FORCING TO
PRODUCE THIS SNOW APPEARS TO BE FROM WARM AIR ADVECTION AROUND
925MB ACCORDING TO 16.14Z RAP BUFKIT SOUNDINGS. THESE SOUNDINGS
ALSO SHOW THE SATURATED THERMAL PROFILE BEING IN THE PEAK
DENDRITIC GROWTH ZONE FROM THE SURFACE UP THROUGH ITS SATURATED
LAYER AT ABOUT 4KFT. THE 16.14Z RAP SHOWS THIS AREA OF HIGH LOW
LEVEL RELATIVE HUMIDITY AND WARM AIR ADVECTION PROPAGATING TO THE
SOUTHEAST THROUGH THE EARLY PART OF THE AFTERNOON BEFORE ENTERING
NORTHERN ILLINOIS AFTER 21Z. SO THE PRECIPITATION SHOULD END THEN.
BASED ON ALL THIS...UPDATED THE FORECAST TO GO FROM FLURRIES TO
THE PERIODS OF SNOW SHOWER THROUGH A PORTION OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA THROUGH 21Z. ALSO ENDED THE FLURRIES
AFTER 21Z REGION-WIDE...BUT THAT WILL HAVE TO BE RE-EVALUATED THIS
AFTERNOON BASED ON THE CLOUD COVER AT THAT TIME.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
240 AM CST SAT FEB 16 2013
THIS SYSTEM WILL THEN PULL AWAY FROM THE REGION MONDAY NIGHT AND
TUESDAY WITH A LINGERING CHANCE FOR SOME LIGHT SNOW ACROSS THE
ENTIRE AREA MONDAY NIGHT AND JUST IN THE I94 CORRIDOR TUESDAY.
AS THIS SYSTEM APPROACHES THE EAST COAST OF CANADA...THE MODELS
NOW SHOW IS SLOWS CONSIDERABLY WITH RIDGING BUILDING OVER THE
CENTRAL PORTIONS OF THE COUNTRY. THE NEXT SYSTEM WILL COME ONSHORE
AND INTO THE ROCKIES TO FORM AN OMEGA BLOCK TYPE PATTERN BY
WEDNESDAY. HOWEVER...THE SYSTEM COMING IN FROM THE WEST IS
EXPECTED TO CONTINUE AN ATTEMPT TO MOVE INTO THE RIDGE AS THERE
WILL BE MORE SYSTEMS TOPPING THE PACIFIC RIDGE AND MOVING TOWARD
THE ROCKIES. THE MODELS NOW SHOW THE FIRST SYSTEM COMING OUT OF
THE WEST TO LIFT INTO THE NORTHERN PLAINS BY FRIDAY AS THE
DOWNSTREAM BLOCK REMAINS IN PLACE AND BEGINS TO FILL IN. THIS IS A
DRAMATIC SHIFT IN THE UPPER AIR PATTERN FROM PREVIOUS MODEL RUNS
WHICH DID NOT SHOW AN OMEGA BLOCK DEVELOPING AND WERE PROGRESSIVE
WITH THE SYSTEM. THE SURFACE LOW IS NOW HANDLED QUITE DIFFERENTLY
BY THE MODELS WITH THEM SHOWING A VERY DEEP LOW COMING OUT OF THE
SOUTHERN ROCKIES WEDNESDAY NIGHT. WITH A FILLING UPPER LEVEL
LOW...ALL THE MODELS SHOW THE SURFACE SYSTEM TO BE FILLING AS
WELL...BUT TO DIFFERENT DEGREES ON HOW FAST THIS WILL HAPPEN.
WOULD HAVE PREFERRED TO LET THE MODEL CONSENSUS GRIDS RIDE UNTIL
CONFIDENCE ON HOW THIS SYSTEM WILL EVOLVE BECOMES HIGHER.
HOWEVER...UNABLE TO DO THIS AND HAD TO RAISE THE PRECIPITATION
CHANCES THURSDAY AFTERNOON AND NIGHT TO REMAIN IN COLLABORATION
WITH SURROUNDING OFFICES. ENDED UP WITH 60 PERCENT ACROSS THE
SOUTHWEST THURSDAY AFTERNOON ON THE LEADING EDGE OF THE
PRECIPITATION SHIELD AND THEN 70 PERCENT FOR MUCH OF THE AREA
THURSDAY NIGHT.
&&
.AVIATION...THROUGH 18Z SUNDAY
1128 AM CST SAT FEB 16 2013
THE MAIN CONCERNS ARE IN THE NEAR TERM WITH SKY CONDITIONS AND
SOME LIGHT SNOW POSSIBLY GETTING INTO RST. THIS BAND OF LIGHT SNOW
HAS BEEN JUST TO THE WEST OF RST ALL MORNING AND HAS BROUGHT
VISIBILITY DOWN TO IFR...MAINLY AT 1-2SM. THE CLOUDS DO APPEAR TO
BE DIMINISHING IN COVERAGE AND THAT SHOULD BE THE TREND THROUGH
THE AFTERNOON HOURS. FURTHER EAST AT LSE..MAINLY LOOKING AT A LOW
END VFR BKN CLOUD DECK AT 3500-4500FT THROUGH THE AFTERNOON BEFORE
SUBSIDENCE KICKS IN AND HELPS CLEAR THE CLOUDS LATER THIS
AFTERNOON ON INTO THE EVENING. WINDS WILL REMAIN LIGHT THROUGH THE
NIGHT AS A RIDGE AXIS OF HIGH PRESSURE MOVES THROUGH BUT AFTER IT
PASSES BY TOMORROW MORNING...THE PRESSURE GRADIENT WILL TIGHTEN UP
WITH SOUTHEAST WINDS INCREASING TO 10-20KTS BY LATE MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 AM CST SAT FEB 16 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1003 AM CST SAT FEB 16 2013
.SHORT TERM...THIS MORNING AND AFTERNOON
1003 AM CST SAT FEB 16 2013
CURRENTLY TRACKING A BAND OF LIGHT SNOW MOVING ACROSS SOUTHEAST
MINNESOTA AND NORTHEAST IOWA WHICH HAS DROPPED VISIBILITY DOWN TO
LESS THAN A MILE AT TIMES. SOME OF THAT MAY BE DUE TO SOME FOG
BEING REPORTED IN CENTRAL MINNESOTA...BUT MOST OF THE VISIBILITY
REDUCTIONS SHOULD BE DUE TO THE SNOW FALLING. AUSTIN CITY POLICE
REPORTED THAT THERE WERE LARGE SNOW FLAKES COMING DOWN AROUND 9AM
AND THAT SOME MINOR ACCUMULATIONS WERE BEGINNING. THE FORCING TO
PRODUCE THIS SNOW APPEARS TO BE FROM WARM AIR ADVECTION AROUND
925MB ACCORDING TO 16.14Z RAP BUFKIT SOUNDINGS. THESE SOUNDINGS
ALSO SHOW THE SATURATED THERMAL PROFILE BEING IN THE PEAK
DENDRITIC GROWTH ZONE FROM THE SURFACE UP THROUGH ITS SATURATED
LAYER AT ABOUT 4KFT. THE 16.14Z RAP SHOWS THIS AREA OF HIGH LOW
LEVEL RELATIVE HUMIDITY AND WARM AIR ADVECTION PROPAGATING TO THE
SOUTHEAST THROUGH THE EARLY PART OF THE AFTERNOON BEFORE ENTERING
NORTHERN ILLINOIS AFTER 21Z. SO THE PRECIPITATION SHOULD END THEN.
BASED ON ALL THIS...UPDATED THE FORECAST TO GO FROM FLURRIES TO
THE PERIODS OF SNOW SHOWER THROUGH A PORTION OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA THROUGH 21Z. ALSO ENDED THE FLURRIES
AFTER 21Z REGION-WIDE...BUT THAT WILL HAVE TO BE RE-EVALUATED THIS
AFTERNOON BASED ON THE CLOUD COVER AT THAT TIME.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
240 AM CST SAT FEB 16 2013
THIS SYSTEM WILL THEN PULL AWAY FROM THE REGION MONDAY NIGHT AND
TUESDAY WITH A LINGERING CHANCE FOR SOME LIGHT SNOW ACROSS THE
ENTIRE AREA MONDAY NIGHT AND JUST IN THE I94 CORRIDOR TUESDAY.
AS THIS SYSTEM APPROACHES THE EAST COAST OF CANADA...THE MODELS
NOW SHOW IS SLOWS CONSIDERABLY WITH RIDGING BUILDING OVER THE
CENTRAL PORTIONS OF THE COUNTRY. THE NEXT SYSTEM WILL COME ONSHORE
AND INTO THE ROCKIES TO FORM AN OMEGA BLOCK TYPE PATTERN BY
WEDNESDAY. HOWEVER...THE SYSTEM COMING IN FROM THE WEST IS
EXPECTED TO CONTINUE AN ATTEMPT TO MOVE INTO THE RIDGE AS THERE
WILL BE MORE SYSTEMS TOPPING THE PACIFIC RIDGE AND MOVING TOWARD
THE ROCKIES. THE MODELS NOW SHOW THE FIRST SYSTEM COMING OUT OF
THE WEST TO LIFT INTO THE NORTHERN PLAINS BY FRIDAY AS THE
DOWNSTREAM BLOCK REMAINS IN PLACE AND BEGINS TO FILL IN. THIS IS A
DRAMATIC SHIFT IN THE UPPER AIR PATTERN FROM PREVIOUS MODEL RUNS
WHICH DID NOT SHOW AN OMEGA BLOCK DEVELOPING AND WERE PROGRESSIVE
WITH THE SYSTEM. THE SURFACE LOW IS NOW HANDLED QUITE DIFFERENTLY
BY THE MODELS WITH THEM SHOWING A VERY DEEP LOW COMING OUT OF THE
SOUTHERN ROCKIES WEDNESDAY NIGHT. WITH A FILLING UPPER LEVEL
LOW...ALL THE MODELS SHOW THE SURFACE SYSTEM TO BE FILLING AS
WELL...BUT TO DIFFERENT DEGREES ON HOW FAST THIS WILL HAPPEN.
WOULD HAVE PREFERRED TO LET THE MODEL CONSENSUS GRIDS RIDE UNTIL
CONFIDENCE ON HOW THIS SYSTEM WILL EVOLVE BECOMES HIGHER.
HOWEVER...UNABLE TO DO THIS AND HAD TO RAISE THE PRECIPITATION
CHANCES THURSDAY AFTERNOON AND NIGHT TO REMAIN IN COLLABORATION
WITH SURROUNDING OFFICES. ENDED UP WITH 60 PERCENT ACROSS THE
SOUTHWEST THURSDAY AFTERNOON ON THE LEADING EDGE OF THE
PRECIPITATION SHIELD AND THEN 70 PERCENT FOR MUCH OF THE AREA
THURSDAY NIGHT.
&&
.AVIATION...TODAY AND TONIGHT
513 AM CST SAT FEB 16 2013
STRATUS WILL PRODUCE PERIODS OF MVFR CONDITIONS AND FLURRIES AT THE
TAF SITES THROUGH THE LATE MORNING HOURS. PLAN ON CLOUD BASES IN
THE 2500 TO 3500 FT RANGE. THE STRATUS SHOULD BECOME SCATTERED
THIS AFTERNOON AS THE HIGH MOVES IN. HOWEVER...GUIDANCE SUGGESTS
THE STRATUS COULD HOLD ON RIGHT ALONG AND EAST OF THE MISSISSIPPI
RIVER LATE THIS AFTERNOON INTO THIS EVENING IMPACTING KLSE.
THINKING THE STRATUS WILL MIX OUT DURING THE AFTERNOON HOURS BUT
WILL HAVE TO KEEP A CLOSE EYE ON THIS. VFR CONDITIONS ARE EXPECTED
DURING THE OVERNIGHT HOURS. SCATTERED TO BROKEN MID LEVEL CLOUDS
WILL MOVE IN FROM THE WEST LATE TONIGHT AS A STORM SYSTEM MOVES
INTO THE NORTHERN PLAINS. WINDS WILL BECOME LIGHT AND VARIABLE
TODAY AS THE HIGH MOVES IN. LOOK FOR WINDS TO SWITCH TO THE
SOUTHEAST AT 5 TO 10 KTS TONIGHT AS THE HIGH SLIDES EAST OF THE
REGION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 AM CST SAT FEB 16 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...04
AVIATION...WETENKAMP