Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/05/13
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
359 PM EST SUN MAR 3 2013
.SYNOPSIS...
LOW PRESSURE MOVING WEST ONTO NOVA SCOTIA THIS EVENING WILL TURN
SOUTHEAST OUT TO SEA...TO THE SOUTH OF NOVA SCOTIA LATE MONDAY.
LOW PRESSURE OVER KENTUCKY TUESDAY WILL SLOWLY INTENSIFY AS IT
REDEVELOPS OVER SOUTHEAST VIRGINIA OR NORTHEAST NORTH CAROLINA
WEDNESDAY. IT THEREAFTER HEADS SLOWLY EAST OR NORTHEAST OUT TO
SEA ON THURSDAY, WITH HIGH PRESSURE BUILDING INTO THE MID ATLANTIC
STATES FRIDAY AND SATURDAY. A WEAK COLD FRONT MAY CROSS THE REGION
LATE SATURDAY OR SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A 19Z SURFACE ANALYSIS PLACED LOW PRESSURE NEAR NOVA SCOTIA. A
NARROW AREA OF HIGH PRESSURE WAS FROM THE LOWER MISSISSIPPI VALLEY
TO THE WESTERN GREAT LAKES. LOW PRESSURE WAS NEAR THE WESTERN
DAKOTAS. AN UPPER AIR ANALYSIS PLACED A CLOSED LOW NEAR SOUTHERN NEW
ENGLAND, WITH A LARGE TROUGH IN THE EASTERN U.S. A RIDGE WAS ACROSS
THE PLAINS, THEN A STRONG TROUGH WAS JUST INLAND FROM THE PACIFIC
NORTHWEST. A FOCUSED AREA OF 850 MB WAA WAS IN THE CENTRAL AND
SOUTHERN PLAINS. A STRONG 250 MB JET WAS FROM THE MIDWEST TO THE
NORTHEASTERN GULF OF MEXICO THEN OFF THE EAST COAST.
THE PERSISTENT UPPER-LEVEL TROUGH ACROSS THE EASTERN U.S. WILL BE
ENHANCED SOME TONIGHT AS A STRONG SHORT WAVE DIVES SOUTHEASTWARD
DOWN THE WESTERN SIDE. AS THIS FEATURE SLIDES MOSTLY TO OUR SOUTH
LATE TONIGHT, THE CLOSED LOW AND ASSOCIATED SURFACE LOW NEAR NOVA
SCOTIA IS FORECAST TO RETROGRADE SOME. THIS IS ALREADY OCCURRING AS
WATER VAPOR IMAGERY SUGGESTS, WHICH IS A RESULT OF A BLOCKING
PATTERN. PRIOR TO THIS THOUGH, OUR SENSIBLE WEATHER IS DRIVEN BY AN
AIRMASS THAT IS QUITE COLD ESPECIALLY ALOFT WITH 500 MB TEMPERATURES
NEAR -27C. THIS RESULTED IN A WEALTH OF STRATOCUMULUS ACROSS THE
AREA, HOWEVER SOME DRYING HAS BEEN EVIDENT WITH DEW POINTS DROPPING
SOME AND ALSO SOME HOLES OPENING UP ACROSS NEW JERSEY. THE FORECAST
SOUNDINGS SUGGEST THAT WHILE SOME ADDITIONAL THINNING COULD OCCUR
THROUGH TONIGHT, A MORE PRONOUNCED LOW-LEVEL INVERSION LOWERS SOME.
WHILE SOME ADDITIONAL DRYING TENDS TO OCCUR, WHATEVER MOISTURE IS
LEFT WOULD TEND TO GET TRAPPED UNDER THIS. THE NAM IS MORE ROBUST
WITH THIS SCENARIO, HOWEVER GIVEN THE PATTERN WE ARE IN, THE CLOUDS
PROBABLY WILL THIN OUT SOME MORE FOR A TIME. WE TRIED TO LEAN IN
THIS DIRECTION ESPECIALLY THE FARTHER EAST AND SOUTH ONE GOES ACROSS
THE CWA.
THE CYCLONIC FLOW AND LINGERING PVA HAS PRODUCED SOME FLURRIES,
ALTHOUGH THIS APPEARS TO BE MORE FOCUSED ACROSS THE FAR NORTHWEST
ZONES NOW. THEREFORE, WE WILL CONTINUE WITH SOME FLURRIES THERE
THROUGH THE NIGHT. INTERESTINGLY ENOUGH SOME OF THE HIGH RESOLUTION
GUIDANCE, SUCH AS THE HRRR AND SPC WRF, SUGGEST SOME FLURRIES OR A
NARROW STREAMER OR TWO OF SNOW SHOWERS ARRIVES MAINLY DURING THE
COURSE OF THIS EVENING. THESE ARE TOUGH TO FORECAST AND WHILE WE
CANNOT RULE IT OUT GIVEN THE SHORT WAVE ENERGY, WE LEFT IT OUT ATTM
DUE TO LOW CONFIDENCE.
A TIGHTENED PRESSURE GRADIENT REMAINS, HOWEVER IT APPEARS THAT THE
VERTICAL MIXING HAS PEAKED. WE WILL STILL HAVE BRISK CONDITIONS FOR
MOST LOCALES INTO THIS EVENING AS SOME GUSTS REACH TO NEAR 25 MPH.
THIS VERTICAL MIXING LOOKS TO GENERALLY DECOUPLE FOR MANY LOCALES
THIS EVENING BEFORE AN UPTICK MAY OCCUR AGAIN. AS THE AFOREMENTIONED
SHORT WAVE AMPLIFIES THE MAIN TROUGH FOR A TIME TONIGHT, THE
PRESSURE GRADIENT IS FORECAST TO TIGHTEN SOME MORE OVERNIGHT. THE
FORECAST SOUNDINGS SUGGEST THAT THE MIXING STARTS TO INCREASE ONCE
AGAIN LATE TONIGHT, THEREFORE THE SURFACE WINDS MAY START TO
RESPOND. THEREFORE, WE TRIED TO DEPICT THIS IN THE GRIDDED DATABASE.
AS FOR LOW TEMPERATURES, WE GENERALLY USED A MOS BLEND WITH JUST
SOME MINOR ADJUSTMENTS. IT WILL BE A RATHER COLD NIGHT, HOWEVER IF
THE WIND PICKS UP AGAIN /OR HOLDS UP ENOUGH/ THEN THIS MAY KEEP THE
AIR TEMPERATURES A BIT HIGHER.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
A BLOCKING PATTERN IS MAINTAINED WITH A CLOSED LOW TENDING TO DRIFT
SOUTHWESTWARD SOME FROM NOVA SCOTIA. A SIGNIFICANT SHORT WAVE THAT
ROTATES UNDERNEATH THIS MAIN UPPER-LEVEL TROUGH LOOKS TO PULL THE
MAIN PORTION OF THE TROUGH TO OUR EAST BY THE END OF THE DAY. AS
THIS OCCURS, OUR REGION REMAINS WITHIN A CYCLONIC FLOW REGIME WITH
EMBEDDED SHORT WAVES STILL MOVING OVERHEAD WITH THE STRONG
NORTHWESTERLY FLOW. THESE SHORT WAVES ARE FORECAST TO BECOME MORE
CHANNELIZED THROUGH THE DAY.
THE FORECAST SOUNDINGS OVERALL SHOW SOMEWHAT DRIER AIR IN PLACE,
WHICH WOULD SUGGEST LESS IN THE WAY OF CLOUDS. SINCE THE CORE OF THE
UPPER-LEVEL TROUGH IS FORECAST TO BE SHIFTING TO OUR EAST, WE WILL
PROBABLY LOSE SOME OF THE THERMAL DIFFERENTIAL FROM THE SURFACE TO
ALOFT. IF THIS IS THE CASE, THE CLOUDS MAY NOT FILL IN AS MUCH.
GIVEN THE CLOSE PROXIMITY OF THE MAIN UPPER-LEVEL TROUGH AND
CYCLONIC FLOW PRESENT, WE STILL CARRIED A FAIR AMOUNT OF CLOUDS. THE
GREATEST IS ACROSS THE NORTHWEST ZONES GIVEN THE COLD FLOW OFF THE
LAKES. WE ALSO CARRIED FLURRIES IN THE POCONOS WITH THIS NORTHWEST
FLOW AND SOME GUIDANCE SUGGESTING SOME LAKE ONTARIO ACTIVITY MAKES
IT INTO NORTHEAST PENNSYLVANIA. THE 850 MB TEMPERATURES ARE FORECAST
TO MODERATE THROUGH THE DAY, SO THIS MAY ALSO KEEP THE CLOUD COVER A
BIT LESS.
AS THE ENTIRE CLOSED LOW RETROGRADES SOME, THE PRESSURE GRADIENT,
ASSOCIATED WITH THE SURFACE LOW TO OUR NORTHEAST AND THEN HIGH
PRESSURE IN THE OHIO VALLEY, WILL TIGHTEN. THE FORECAST SOUNDINGS
INDICATE STRONGER FLOW ABOVE THE SURFACE AND THE LOW-LEVEL LAPSE
RATES STEEPENING. THIS LEADS TO DEEPER VERTICAL MIXING AS WE GO
THROUGH THE MORNING AND AFTERNOON. AS A RESULT, WE ARE ANTICIPATING
A BREEZY TO WINDY DAY /PEAK GUSTS NEAR 30 MPH/.
AS FOR TEMPERATURES, WE WENT WITH AN EVEN NAM/GFS BLEND. THE AIRMASS
IS STILL CHILLY DESPITE IT STARTING TO MODERATE ALOFT, THEREFORE WE
LEANED A BIT MORE TOWARD THE COOLER GUIDANCE FOR MANY LOCALES.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
**SUBSTANTIAL LONG DURATION NOREASTER FOR AT LEAST THE SOUTHERN
PORTION OF OUR AREA WEDNESDAY INTO THURSDAY**
DEFERRED ON WATCHES AT THIS TIME SINCE WE`RE FORECAST FOR PERIODS
6-8...72 TO 96 HOURS IN ADVANCE.
THOSE WITH CONCERNS FOR S NJ...DE AND E MD SHORE AND FAR SE PA
WEDNESDAY INTO THURSDAY SHOULD MONITOR LATER STATEMENTS...WATCHES
AND POSSIBLE WARNINGS FOR THE FOLLOWING HAZARDS BEGINNING TOMORROW
MORNING:
COASTAL FLOOD...MODERATE OR MAJOR COASTAL FLOOD THREAT FOR THE S
NJ AND ESPECIALLY DELAWARE ATLANTIC COAST. PLEASE SEE TIDE SECTION
FOR MORE DETAILS.
WIND...POTENTIAL HIGH WIND EVENT /60 MPH GUSTS/ FOR COASTAL SOUTHERN
NEW JERSEY AND ESPECIALLY COASTAL DELAWARE WITH WIND ADVISORY
POTENTIAL FOR THE REMAINDER OF SOUTHERN AND CENTRAL DELAWARE...E
MD AND INTERIOR SOUTH THIRD OF NJ POSSIBLY THROUGH PHILADELPHIA
AND SE PA.
SNOW...ESPECIALLY ELEVATIONS. THE BOUNDARY LAYER TEMPERATURE
GOVERNS RAIN/SNOW.
RIGHT NOW THE LOWEST 50 MB ABOVE 0C LAYER IS THE DIFFICULTY ON
CONFIDENTLY FORECASTING A MAJOR WET SNOW. IT IS ANTICIPATED THAT
THERE WILL BE A PERIOD OF HEAVY WET SNOW THAT WILL ACCUMULATE
SEVERAL SLOPPY INCHES IN PARTS OF OUR AREA...ESPECIALLY NORTHERN
DELAWARE AND ADJACENT NE MD AND POSSIBLY SE PA. 06Z-12Z/3 GFS
DENDRITE GROWTH LOOKS TO BE SUBSTANTIAL FOR 12 HOURS WEDNESDAY
OVER E MD AND DE. HOWEVER... ITS FAR TOO EARLY TO BE CONFIDENT ON
AMOUNTS... TIMING AND AREAL COVERAGE. IF THIS RAIN CHANGING TO
HEAVY WET SNOW DOES OCCUR...AND IT LASTS FOR 6 HOURS OR MORE WITH
THE SURFACE TEMP 33F...WE WOULD HAVE A CHANCE FOR POWER OUTAGES
DUE TO WET SNOW ACCRETION ON TREES AND WIRES. AGAIN FAR TOO EARLY.
FOR NOW OUR SNOW GRIDS ARE VERY CONSERVATIVE DUE TO THE SFC TEMPS.
HYDRO...NO CONCERNS EXCEPT FOR PERIODS OF NUISANCE POOR DRAINAGE
FLOODING...PROVIDED THE AXIS OF 1 TO 3 INCHES OF RAIN DOES NOT
CREEP NORTH OF WILMINGTON.
OVERALL PATTERN THIS FORECAST PERIOD: BLOCKING PATTERN IN NORTHEAST
CANADA SLOWLY ERODES BY THE END OF THE WEEK. THE PRIMARY SHORTWAVE
IS ALREADY CLOSING OFF OVER THE DAKOTAS MONDAY EVENING ARRIVING OVER
NORTHEAST NORTH CAROLINA OR SOUTHEAST VIRGINIA WEDNESDAY. IT THEN
HEADS SLOWLY EAST OUT TO SEA AND WEAKENS BY FRIDAY AS RIDGING DEVELOPS
ALONG THE EAST COAST. WEAK TROUGHING REPLACES THE PREVIOUS BLOCK
OVER NORTHEAST CANADA BY SUNDAY WHILE A NEW LARGE SCALE CLOSED LOW
DRIFTS EAST INTO THE SOUTHERN AND CENTRAL PLAINS.
CALENDAR DAY AVERAGE TEMPS: NEAR OR A BIT BELOW NORMAL TUESDAY AND
WEDNESDAY THEN SLOWLY WARMING ABOVE NORMAL SO THAT BY FRIDAY...
SATURDAY AND SUNDAY TEMPS MAY BE AVERAGING ALMOST 5 DEGREES ABOVE
NORMAL.
THE DAILIES BELOW...
STATISTICAL GUIDANCE GOVERNING THIS FORECAST WAS A BLEND OF THE
12Z/3 GFS/NAM MOS THROUGH TUE NIGHT...THEN THE GFS MEX MOS WED
THROUGH THURSDAY WITH SOME COLDER 2M TEMP BLENDING. FOR THURSDAY NIGHT
AND BEYOND...RELIED SOLELY ON 15Z/3 HPC GUIDANCE UNLESS OTHERWISE
NOTED. HAVE NOT SPENT MUCH TIME ADJUSTING THE HPC FORECAST FOR THE
PERIOD THURSDAY NIGHT THROUGH SUNDAY WITH ANY ADJUSTMENTS FOCUSED
IN THE TUE NIGHT-THU AFTERNOON TIME FRAME...ESPECIALLY SINCE THE
12Z ECMWF OP HIGH RES RUN DID NOT ARRIVE IN TIME FOR DIRECT
INCLUSION INTO THE FORECAST.
THE DAILIES BELOW...
MONDAY NIGHT AND TUESDAY...FAIR SEASONABLY COOL WEATHER WITH
DIMINISHING NW WIND GUSTS OF 20-25 MPH MONDAY EVENING BECOMING LIGHT
NORTH OR NORTHEAST TUESDAY AFTERNOON.
TUESDAY NIGHT...INCREASING AND THICKENING CLOUDS. CHANCE OF SNOW OR
PRECIPITATION LATE. CONSERVATIVE FORECAST WITH BLENDED 12Z/3 NCEP
MOS GUIDANCE. WE DID NOTE THE UKMET DROPPING .04 DOWN INTO NE NJ
SEPARATELY FROM THE ONCOMING MID ATLANTIC CLOSED LOW BUT DID NOT
PLAY THIS UP. IN ANY CASE...A COVERING OF SNOW IS POSSIBLE BY
DAYBREAK WEDNESDAY BUT DIDNT PLAY THIS UP DUE TO ONSET OF PCPN
TIMING ISSUE AND PTYPE/SFC TEMP. PLEASE MONITOR LATER FORECASTS.
IT COULD BE A SLIPPERY START TO WEDNESDAY IN SE PA AND NE MD.
WEDNESDAY...STORMY OVER THE SRN PART OF THE AREA. PLAYED THIS
MOSTLY AS RAIN DUE TO THE ABOVE FREEZING BOUNDARY LAYER BUT IT
COULD BE A CLOSE CALL IN PARTS OF MD WESTERN DELAWARE AND SE PA.
LONG WAYS TO GO...SO WE CAN TRY TO IRON OUT EXPECTATIONS AS WE
DRAW CLOSER TO THE EVENT. 12Z/3 NCEP GUIDANCE POPS WERE TRIMMED
IN NE PA AND NNJ RESPECTING THE SOUTHWARD ECMWF/UKMET CAMP. COULD
BE A SHARP CUTOFF ON THE NRN EDGE GOING FROM NO PCPN TO OVER HALF
AN INCH IN 50 MILES. ALSO CONCERNED ABOUT 60 MPH WIND GUSTS IN DE
AND FAR SE NJ.
SO...A MULTI HAZARD DAY. WIND...COASTAL FLOODING...POSSIBLY SNOW
AND POOR DRAINAGE FLOODING...MOSTLY DE/MD/S NJ AND FAR SE PA.
PLEASE NOTE THE FORECAST WORDING IN SOME OF THE ZONES IS LESS THAN
DETERMINISTICALLY IDEAL BUT WHERE ITS COMPLEX...ALSO STATES WHERE
THERE IS GREATER UNCERTAINTY AS TO THE PTYPE.
THURSDAY...SLOW CLEARING FM WEST TO EAST...TIMING OF THIS PROCESS
UNCERTAIN AT THIS TIME. WINDY NORTHERLY FLOW WITH GUSTS 25 TO 35
MPH.
THURSDAY NIGHT-SUNDAY...GENERALLY FAIR WEATHER EXPECTED WITH
GUSTY NORTH NORTHWEST WINDS OF 20 TO 25 MPH THROUGH FRIDAY
BECOMING LIGHT SATURDAY. HPC GUIDANCE FOLLOWED CLOSELY.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF THIS AFTERNOON...VFR CEILINGS, WITH THE MAIN BASES
BETWEEN 4,000 AND 6,000 FEET. THERE IS AN AREA OF SOME DRIER AIR
WORKING SOUTHWARD ACROSS NEW JERSEY AND FAR EASTERN PENNSYLVANIA,
AND THIS SHOULD THIN OUT THE CLOUDS ESPECIALLY AT MANY OF THE
TERMINALS. NORTHWEST WINDS 10-15 KNOTS WITH LOCAL GUSTS TO NEAR 20
KNOTS.
TONIGHT...VFR. THE CEILINGS THINNING OUT SHOULD FILL BACK IN,
ESPECIALLY NORTH AND WEST OF THE KPHL METRO AREA. NORTHWEST
WINDS AROUND 10 KNOTS, HOWEVER SOME GUSTS MAY OCCUR AGAIN ESPECIALLY
LATE.
MONDAY...VFR. NORTHWEST WINDS 15-20 WITH GUSTS TO AROUND 25 KNOTS.
OUTLOOK...
MON NIGHT...VFR EXCEPT POSSIBLE MVFR CIGS VCNTY KMPO CLEARING LATE.
NW WIND GUST 15-25 KTS TO BEGIN THE EVENING...THEN DIMINISHING.
HIGH CONFIDENCE.
TUESDAY...VFR. LIGHT NORTH WIND BECOMING NORTHEAST. HIGH CONFIDENCE.
TUESDAY NIGHT...CONDS MAY LOWER TO MVFR IF PRECIPITATION DEVELOPS
LATE. INCREASING NE WIND LATE. BELOW AVERAGE CONFIDENCE ON DETAILS.
WED...MVFR OR IFR CONDS IN RAIN OCCASIONALLY CHANGING TO SNOW...ESPECIALLY
KPHL SOUTH. NE WIND SHOULD GENERALLY GUST 25-35 KTS DURING THE DAY
AND EVENING WITH HIGHER GUSTS TO 45 KNOTS ALONG THE COAST. AVERAGE
CONFIDENCE.
THU...ANY SUB VFR CONDITIONS EARLY...IMPROVING TO VFR. NNW WIND G
25-35 KTS DURING THE DAY. AVERAGE CONFIDENCE.
FRI...VFR. NNW WIND G20-25 KTS DURING THE DAY. HIGH CONFIDENCE.
&&
.MARINE...
A TIGHT ENOUGH PRESSURE COMBINED WITH A COLD AIRMASS IS MAINTAINING
ENOUGH VERTICAL MIXING. THE NORTHWEST FLOW IS ALIGNED ENOUGH TO
FUNNEL DOWN THE LENGTH OF DELAWARE BAY. THIS HAS RESULTED IN GUSTS
TO AROUND 25 KNOTS ESPECIALLY AROUND THE BAY MOUTH. THE FORECAST
SOUNDINGS INDICATE THAT THE FLOW INCREASES SOME THROUGH THE NIGHT,
WITH THE LOW-LEVEL LAPSE RATES STEEPENING. AS THIS OCCURS, THE
MIXING SHOULD DEEPEN A BIT MORE ACROSS ALL OF OUR WATERS. AS A
RESULT, THE SMALL CRAFT ADVISORY IS IN EFFECT THROUGH TONIGHT. THE
STRONG NORTHWEST FLOW AND CHILLY AIRMASS IS EXPECTED TO MAINTAIN
DEEPER MIXING MONDAY AS WELL, THUS THE PREVIOUSLY ISSUED ADVISORY
REMAINS IN EFFECT THROUGH THE DAY MONDAY. SEAS 2-4 FEET SHOULD
INCREASE A LITTLE MORE DUE TO THE UPTICK IN THE WINDS, HOWEVER GIVEN
THE OFFSHORE FLOW, THE HIGHEST SEAS SHOULD BE FARTHER OFFSHORE AND
IN LOWER DELAWARE BAY AND THROUGH THE BAY MOUTH.
OUTLOOK...
SCA WAS EXTENDED TIL ABOUT MIDNIGHT MONDAY NIGHT FOR LEFTOVER NW
FLOW GUSTS TO 25 OR 30 KT. SOME OF THE GUIDANCE SUGGESTS SCT 35 KT
GUSTS NJ AND DE BAY ENTRANCE MONDAY EVENING.
TUESDAY...NO HEADLINE ANTICIPATED AS WINDS DIMINISH AND BECOMING
LIGHT NORTH. NE WINDS INCREASE LATE TUE NIGHT.
WEDNESDAY INTO THURSDAY...AT A MINIMUM A GALE WARNING. A GOOD CHANCE
WE`LL NEED A STORM WARNING...ESPECIALLY VCNTY CAPE MAY SOUTHWARD.
SEAS TO AT LEAST 15 FEET OFF THE SNJ AND DE COAST WITH POSSIBLE 20
FT AT THE 44009 BUOY.
PRIMARY THREAT FOR STRONGEST WIND APPEARS TO BE CENTERED WEDNESDAY
EVENING WITHIN SEVERAL HOURS OF 7 PM.
FRIDAY...ATLC WATERS AN SCA FOR LEFTOVER NE SWELL OF 5 TO 8 FEET AND
13 SECONDS. DE WATERS MIGHT NEED AN SCA FOR WIND GUSTS.
&&
.TIDES/COASTAL FLOODING...
EXPECTING A WATCH WILL BE NEEDED FOR MULTIPLE TIDE CYCLES ALONG
THE ATLC COAST WED AFTERNOON AND THURSDAY MORNING HIGH TIDES...
ESPECIALLY ATLANTIC CITY SOUTH. EVEN THE TIDAL DELAWARE WILL
PROBABLY NEED AN ADVISORY FOR THE WED EVENING AND THURSDAY
DAYBREAK HIGH TIDE CYCLES.
SURGE OF NEARLY 4 FEET IS EXPECTED WITH THE PRIMARY DANGER PERIOD
THE EARLY THURSDAY MORNING HIGH TIDE CYCLE ALONG THE ATLANTIC
COAST...ESPECIALLY DELAWARE. SEAS OF 15 FEET ARE PROBABLY POUNDING
THE DELAWARE COAST WITH WIND GUSTS TO AT LEAST 50 MPH WEDNESDAY
NIGHT. HOWEVER...SINCE THE MODELS ARE TRENDING A BIT FASTER... ITS
YET POSSIBLE THE THE WEDNESDAY AFTERNOON STORM TIDE WILL EQUAL THAT
OF THURSDAY MORNING.
SURGE AT LOW AND HIGH TIDE WEDNESDAY NIGHT ON THE ATLANTIC WATERS
NEAR OR AROUND 4 FEET...WHICH COMBINED WITH POSSIBLE HEAVY
RAINFALL...COULD MEAN TIDAL INUNDATION FLOODING OF ABOUT 3 HOURS
EITHER SIDE OF THE THE HIGH TIDE.
A SURGE OF 3.6 FEET WEDNESDAY AFTERNOON AND 2.5 FEET THURSDAY
MORNING WOULD REACH THE THRESHOLD OF MDT COASTAL FLOODING WHICH
SEEMS ALMOST A CERTAINTY IN DELAWARE. ADD A FOOT FOR MAJOR WHICH IS
A LOWER RISK BUT QUITE POSSIBLE AND ALREADY MODELED BY A RATHER
STRONG 12Z GFS CYCLE. IF FUTURE MODEL RUNS ARE WEAKER...THEN THE
SURGE AND CONSEQUENT POTENTIAL FOR A MAJOR COASTAL FLOOD EVENT
WOULD BE LESS.
ALL OF THIS IS IMPORTANT...PARTLY BECAUSE OF OF THE DAMAGE
INCURRED WITH SANDY THIS PAST OCTOBER BUT ALSO SINCE SOME OF MODEL
GUIDANCE IS OUTLOOKING ABOUT THE 3RD OR 4TH HIGHEST STORM TIDE ON
RECORD FOR LEWES. THAT VALUE IS NOT A DONE DEAL BUT ITS IN THE MIX
OF POSSIBILITIES.
HERE ARE THE TIMES OF HIGH TIDE AND THE FORECAST ASTRONOMICAL TIDE
HEIGHTS FOR SELECTED POINTS ALONG THE COAST. THE FORECAST
ASTRONOMICAL TIDE HEIGHT PLUS THE ACTUAL STORM SURGE WILL EQUAL THE
ACTUAL WATER LEVEL AT THE TIME OF HIGH TIDE.
ALL HEIGHTS ARE IN MEAN LOWER LOW WATER (MLLW).
WEDNESDAY THURSDAY
REHOBOTH BEACH DE 3.2 FT AT 250 PM 4.2 FT AT 335 AM
LEWES DE 3.6 FT AT 355 PM 4.6 FT AT 434 AM
CAPE MAY NJ (OCEANFRONT) 3.8 FT AT 319 PM 5.0 FT AT 354 AM
ATLANTIC CITY NJ 3.4 FT AT 245 PM 4.5 FT AT 320 AM
SEASIDE HEIGHTS NJ (OCEANFRONT) 4.0 FT AT 228 PM 4.7 FT AT 301 AM
SANDY HOOK NJ 4.3 FT AT 258 PM 5.1 FT AT 331 AM
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ450>455.
SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ430-431.
&&
$$
SYNOPSIS...DRAG 357
NEAR TERM...GORSE 357
SHORT TERM...GORSE 357
LONG TERM...DRAG 357
AVIATION...DRAG/GORSE 357
MARINE...DRAG/GORSE 357
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
719 AM EST SUN MAR 3 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT AND REMAIN
THROUGH EARLY THIS WEEK. LOW PRESSURE AND ITS TRAILING COLD FRONT
WILL IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE REGION WILL REMAIN UNDER THE INFLUENCE OF A DEEP LONGWAVE
TROUGH TODAY. THE TROUGH IS FORECAST TO GRADUALLY PUSH OFFSHORE AS
THE DAY PROGRESSES ALLOWING MID-LEVEL HEIGHTS TO STEADILY RISE IN
ITS WAKE. ALTHOUGH THE MID-LEVEL THERMAL ADVECTION PATTERN WILL
BECOME NEUTRAL TO SLIGHTLY POSITIVE LATER TODAY...H8 TEMPERATURES
OF -6 TO -7C WILL STILL KEEP HIGH TEMPERATURES ABOUT 10-15 DEGREES
BELOW NORMAL FOR EARLY MARCH. LOW-LEVEL THICKNESSES SCHEMES
SUPPORT HIGHS IN THE LOWER 50S WHICH LOOK REASONABLE PER MODEL
BUFR SOUNDINGS.
STEEP MID-LEVEL LAPSE RATES NEARING 6 C/KM COUPLED WITH SOME
LINGERING MID-LEVEL MOISTURE WILL LIKELY SUPPORT THE FORMATION OF
SOME SORT OF SHALLOW CUMULUS FIELD ONCE THE NOCTURNAL INVERSION
BURNS OFF. HOWEVER...IT IS UNCLEAR HOW EXTENSIVE THIS CLOUD DECK
WILL BECOME. BUFKIT CLOUD TOOLS SUGGEST A RATHER THICK 6 KFT CLOUD
LAYER WILL FORM...WHILE OTHER DATA SUCH AS THE WRF AND GEM
SIMULATED SATELLITE PRODUCTS SUPPORT CONSIDERABLY LESS CLOUD
COVER. CONSIDERING THE H9-H7 FLOW DOES NOT BECOME TRULY DOWNSLOPE
DOMINATED UNTIL MID-LATE AFTERNOON...SUSPECT THERE WILL BE ENOUGH
CLOUDS TO SUPPORT A PARTLY CLOUDY SKY CHARACTER...HOWEVER SKIES
RANGING ANYWHERE FROM CLOUDY TO COMPLETELY SUNNY ARE DISTINCT
POSSIBILITIES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST
TONIGHT AS WEAK UPPER RIDGING OVER THE SOUTHERN PLAINS NUDGES
EAST. THERE LOOKS TO BE ENOUGH OF A RESIDUAL PRESSURE GRADIENT
ALONG THE EASTERN FLANKS OF THE SURFACE HIGH TO PREVENT FULL
BOUNDARY LAYER DECOUPLING AFTER SUNSET...EXCEPT OVER INTERIOR
SOUTHEAST GEORGIA WHERE DECOUPLING APPEARS MORE LIKELY. LOWS WILL
RANGE FROM THE UPPER 20S INLAND TO THE MID 30S AT THE BEACHES WITH
A FEW MID 20S LIKELY IN SOME SHELTERED AREAS OF FAR INTERIOR
SOUTHEAST GEORGIA.
MONDAY...SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT WILL
QUICKLY FOLLOW IN THE WAKE OF THE DEPARTING UPPER TROUGH EARLY IN
THE DAY. MODEL FORECAST SOUNDINGS INDICATE DEEP LAYER DRY AIR DURING
THE DAYTIME HOURS WITHIN A PREDOMINANT WEST/NORTHWEST FLOW. HIGH
LEVEL CLOUDS COULD THEN SHIFT INTO THE AREA OVERNIGHT DOWNSTREAM OF
A DEVELOPING LOW IN THE LOWER MISSISSIPPI/TENNESSEE VALLEYS. RISING
HEIGHTS ALOFT AND MOSTLY CLEAR TO PARTLY CLOUDY SKIES WILL SUPPORT
MODERATING TEMPERATURES...WITH HIGHS REACHING THE UPPER 50S TO LOWER
60S AWAY FROM THE LOCALLY COOLER COASTLINE. LOW LEVEL FLOW WILL BACK
TO THE SOUTHWEST OVERNIGHT...AND WITH EVIDENCE OF SOME HIGHER LEVEL
CLOUDS PROVIDING INSULATING EFFECTS AFTER MIDNIGHT...EXPECT LOW
TEMPERATURES TO BE NEARLY 10 DEGREES WARMER THAN THE PREVIOUS NIGHT.
LOWS WILL THUS RANGE FROM THE UPPER 30S INLAND TO THE LOWER 40S NEAR
THE BEACHES.
TUESDAY...A POTENT SHORTWAVE TROUGH WILL DESCEND FROM THE NORTHERN
PLAINS STATES INTO THE MID MISSISSIPPI VALLEY THROUGH THE AFTERNOON
HOURS...PROVIDING SIGNIFICANT ENERGY TO ORGANIZE AND INTENSIFY A
SURFACE LOW SYSTEM OVER THE TENNESSEE VALLEY BY SUNSET. THE UPPER
TROUGH WILL DEVELOP INTO A CUT OFF LOW OVERNIGHT...AT THE SAME TIME
THAT THE SURFACE SYSTEM BECOMES MORE COMPLEX AND TRACKS DUE
EASTWARD THROUGH THE CAROLINAS AND MID ATLANTIC STATES BY DAYBREAK
WEDNESDAY. THE FORECAST AREA WILL BE LOCATED WITHIN THE WARM
SECTOR OF THE SYSTEM DURING THE DAYTIME HOURS TUESDAY...WITH
SOUTHERLY FLOW SUPPORTING TEMPERATURES RISING INTO THE UPPER 60S
NORTHWEST ZONES TO THE LOWER 70S SOUTH OF THE SAVANNAH RIVER. WITH
THE FORECAST AREA INITIALLY LOCATED SOUTH OF THE WARM FRONT AND
WEST OF THE APPROACHING COLD FRONT...EXPECT RAIN TO BE SLOW TO
PUSH INTO THE REGION THROUGH THE AFTERNOON HOURS. RAIN CHANCES
WILL THEN INCREASE SIGNIFICANTLY AFTER SUNSET ONCE THE FRONT AND
UPPER LOW PASS OVER THE SOUTHEAST AND MID ATLANTIC STATES. GIVEN
DECENT MODEL AGREEMENT IN POTENTIAL AND COVERAGE OF RAIN...HAVE
INCREASED POPS INTO THE LIKELY RANGE FOR MUCH OF THE FORECAST AREA
FROM AROUND MIDNIGHT TO DAYBREAK WEDNESDAY MORNING. THICK
INSULATING CLOUD COVER...ALONG WITH SOUTHERLY FLOW VEERING TO THE
WEST...WILL KEEP LOW TEMPERATURES TUESDAY NIGHT RATHER MILD IN THE
UPPER 40S TO LOWER 50S.
WEDNESDAY...THE STACKED AND INTENSIFYING LOW SYSTEM WILL LIFT
EAST/NORTHEAST DURING THE MORNING HOURS...WHILE THE TRAILING COLD
FRONT RAPIDLY MOVES OFFSHORE. RAIN CHANCES WILL BE DECREASING FROM
WEST TO EAST INTO THE EARLY AFTERNOON...AND WITH THE SURFACE LOW
DISPLACED NORTH OF THE FORECAST AREA BY DAYBREAK...WRAP AROUND
MOISTURE DOES NOT APPEAR TO BE A CONCERN AT THIS TIME. HIGH
TEMPERATURES WILL BE COOLER IN THE UPPER 50S TO LOWER 60S BEHIND
THE DEPARTING COLD FRONT...HOWEVER MODERATE TO STRONG
OFFSHORE/DOWNSLOPE FLOW AND LINGERING CLOUD COVER WILL MITIGATE
MORE SIGNIFICANT COOLING POTENTIAL. A GREATLY TIGHTENED PRESSURE
GRADIENT ON THE BACKSIDE OF THE SURFACE LOW...AS WELL AS COLD
ADVECTION ENHANCING MIXING INTO A 30 TO 40 KT LOW LEVEL
JET...SUGGESTS BREEZY TO GUSTY WEST WINDS DURING THE AFTERNOON
HOURS.
LAKE WINDS...WINDS WILL APPROACH ADVISORY CRITERIA TUESDAY
AFTERNOON AS A 40 KT LOW LEVEL JET PASSES OVER THE REGION.
HOWEVER...MIXING WILL BE LIMITED WITHIN A WARM ADVECTION REGIME
OVER THE COOLER LAKE WATERS. A BETTER CHANCE FOR LAKE WIND
ADVISORY THRESHOLDS TO BE MET IS ON WEDNESDAY...AS A SIGNIFICANTLY
TIGHTENED PRESSURE GRADIENT AND STRONG COLD ADVECTION ENHANCES
MIXING AND SUPPORTS 20 TO 25 KT WINDS OVER THE LAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS THE POTENT LOW SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH
THE LATE WEEK PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL
RIDGING WILL FOLLOW IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS
PREVAIL THURSDAY THROUGH THE WEEKEND. RISING HEIGHTS ALOFT WILL
SUPPORT A GRADUAL WARMING TREND THROUGH THE PERIOD...WITH
TEMPERATURES PEAKING IN THE LOW TO MID 60S THURSDAY AND
FRIDAY...THEN POSSIBLY THE LOW 70S SATURDAY AND SUNDAY. LOW
TEMPERATURES WILL ALSO MODERATE INTO THE UPPER 30S TO LOWER 40S BY
LATE PERIOD.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF REDUCED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
THIS MORNING...WINDS REMAIN QUITE RISKY AT BUOY 41008 WHICH IS A
BIT HIGHER THAN THE LATEST RAP RUN. WILL EXTEND THE SMALL CRAFT
ADVISORY FOR BOTH GEORGIA LEGS UNTIL 11 AM.
TODAY...WINDS WILL SLOWLY SUBSIDE ACROSS THE MARINE AREA TODAY AS
COLD AIR ADVECTION STEADILY WANES. ONCE THE MORNING SURGE
CEASES...EXPECT WINDS TO SETTLE INTO THE 10-15 KT RANGE...EXCEPT
15-20 KT OVER THE GEORGIA OFFSHORE WATERS. SEAS WILL RANGE FROM
2-3 FT NEARSHORE WATERS AND 3-4 FT OFFSHORE WATERS
TONIGHT...ANOTHER SURGE LOOKS LIKELY OVER THE WATERS TONIGHT AS
THE PRESSURE GRADIENT TIGHTENS A BIT AHEAD OF HIGH PRESSURE
NUDGING IN FROM THE WEST. SHOULD SEE AT LEAST FREQUENT GUSTS TO 25
KT OCCUR OVER THE WARMER WATERS ACROSS THE EASTERN PORTIONS FOR
THE GEORGIA OFFSHORE LEG...SO A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED THERE. IT LOOKS A BIT MORE MARGINAL OVER THE NEARSHORE
WATERS SO WILL NOT HOIST AN ADVISORY JUST YET. SEAS WILL RANGE
FROM 2-4 FT NEARSHORE WATERS...4-6 FT OFFSHORE WATERS.
MONDAY...COLD ADVECTION WILL DIMINISH BY MID MORNING...AND ANY
SMALL CRAFT ADVISORIES SHOULD BE ALLOWED TO EXPIRE AT THAT TIME.
SOUTHERLY FLOW WILL THEN REMAIN BELOW ADVISORY THRESHOLDS FOR THE
REMAINDER OF THE DAY...AS HIGH PRESSURE BUILDS IN FROM FLORIDA AND
SETTLES OVER THE MARINE ZONES.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY...AS ATLANTIC HIGH PRESSURE SHIFTS FARTHER AWAY FROM
THE MARINE ZONES AHEAD OF AN INTENSIFYING LOW PRESSURE SYSTEM
MOVING INTO THE TENNESSEE VALLEY. THE POTENT LOW SYSTEM WILL
INTENSIFY AS IT SHIFTS INTO THE CAROLINAS LATE TUESDAY/EARLY
WEDNESDAY AND THEN OFF THE MID ATLANTIC COAST WEDNESDAY
NIGHT/THURSDAY. A TRAILING COLD FRONT WILL SWEEP THROUGH THE
MARINE ZONES LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. SMALL CRAFT
ADVISORY CRITERIA WILL BE REACHED BOTH AHEAD OF THE FRONT AND IN
ITS WAKE DURING THE MID WEEK PERIOD...WHILE THERE IS ALSO A GOOD
POTENTIAL FOR GALE CONDITIONS TO BE REACHED. WILL CONTINUE TO
MENTION THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR AMZ354-
374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
615 AM EST SUN MAR 3 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT AND REMAIN
THROUGH EARLY THIS WEEK. LOW PRESSURE AND ITS TRAILING COLD FRONT
WILL IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE REGION WILL REMAIN UNDER THE INFLUENCE OF A DEEP LONGWAVE
TROUGH TODAY. THE TROUGH IS FORECAST TO GRADUALLY PUSH OFFSHORE AS
THE DAY PROGRESSES ALLOWING MID-LEVEL HEIGHTS TO STEADILY RISE IN
ITS WAKE. ALTHOUGH THE MID-LEVEL THERMAL ADVECTION PATTERN WILL
BECOME NEUTRAL TO SLIGHTLY POSITIVE LATER TODAY...H8 TEMPERATURES
OF -6 TO -7C WILL STILL KEEP HIGH TEMPERATURES ABOUT 10-15 DEGREES
BELOW NORMAL FOR EARLY MARCH. LOW-LEVEL THICKNESSES SCHEMES
SUPPORT HIGHS IN THE LOWER 50S WHICH LOOK REASONABLE PER MODEL
BUFR SOUNDINGS.
STEEP MID-LEVEL LAPSE RATES NEARING 6 C/KM COUPLED WITH SOME
LINGERING MID-LEVEL MOISTURE WILL LIKELY SUPPORT THE FORMATION OF
SOME SORT OF SHALLOW CUMULUS FIELD ONCE THE NOCTURNAL INVERSION
BURNS OFF. HOWEVER...IT IS UNCLEAR HOW EXTENSIVE THIS CLOUD DECK
WILL BECOME. BUFKIT CLOUD TOOLS SUGGEST A RATHER THICK 6 KFT CLOUD
LAYER WILL FORM...WHILE OTHER DATA SUCH AS THE WRF AND GEM
SIMULATED SATELLITE PRODUCTS SUPPORT CONSIDERABLY LESS CLOUD
COVER. CONSIDERING THE H9-H7 FLOW DOES NOT BECOME TRULY DOWNSLOPE
DOMINATED UNTIL MID-LATE AFTERNOON...SUSPECT THERE WILL BE ENOUGH
CLOUDS TO SUPPORT A PARTLY CLOUDY SKY CHARACTER...HOWEVER SKIES
RANGING ANYWHERE FROM CLOUDY TO COMPLETELY SUNNY ARE DISTINCT
POSSIBILITIES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST
TONIGHT AS WEAK UPPER RIDGING OVER THE SOUTHERN PLAINS NUDGES
EAST. THERE LOOKS TO BE ENOUGH OF A RESIDUAL PRESSURE GRADIENT
ALONG THE EASTERN FLANKS OF THE SURFACE HIGH TO PREVENT FULL
BOUNDARY LAYER DECOUPLING AFTER SUNSET...EXCEPT OVER INTERIOR
SOUTHEAST GEORGIA WHERE DECOUPLING APPEARS MORE LIKELY. LOWS WILL
RANGE FROM THE UPPER 20S INLAND TO THE MID 30S AT THE BEACHES WITH
A FEW MID 20S LIKELY IN SOME SHELTERED AREAS OF FAR INTERIOR
SOUTHEAST GEORGIA.
MONDAY...SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT WILL
QUICKLY FOLLOW IN THE WAKE OF THE DEPARTING UPPER TROUGH EARLY IN
THE DAY. MODEL FORECAST SOUNDINGS INDICATE DEEP LAYER DRY AIR DURING
THE DAYTIME HOURS WITHIN A PREDOMINANT WEST/NORTHWEST FLOW. HIGH
LEVEL CLOUDS COULD THEN SHIFT INTO THE AREA OVERNIGHT DOWNSTREAM OF
A DEVELOPING LOW IN THE LOWER MISSISSIPPI/TENNESSEE VALLEYS. RISING
HEIGHTS ALOFT AND MOSTLY CLEAR TO PARTLY CLOUDY SKIES WILL SUPPORT
MODERATING TEMPERATURES...WITH HIGHS REACHING THE UPPER 50S TO LOWER
60S AWAY FROM THE LOCALLY COOLER COASTLINE. LOW LEVEL FLOW WILL BACK
TO THE SOUTHWEST OVERNIGHT...AND WITH EVIDENCE OF SOME HIGHER LEVEL
CLOUDS PROVIDING INSULATING EFFECTS AFTER MIDNIGHT...EXPECT LOW
TEMPERATURES TO BE NEARLY 10 DEGREES WARMER THAN THE PREVIOUS NIGHT.
LOWS WILL THUS RANGE FROM THE UPPER 30S INLAND TO THE LOWER 40S NEAR
THE BEACHES.
TUESDAY...A POTENT SHORTWAVE TROUGH WILL DESCEND FROM THE NORTHERN
PLAINS STATES INTO THE MID MISSISSIPPI VALLEY THROUGH THE AFTERNOON
HOURS...PROVIDING SIGNIFICANT ENERGY TO ORGANIZE AND INTENSIFY A
SURFACE LOW SYSTEM OVER THE TENNESSEE VALLEY BY SUNSET. THE UPPER
TROUGH WILL DEVELOP INTO A CUT OFF LOW OVERNIGHT...AT THE SAME TIME
THAT THE SURFACE SYSTEM BECOMES MORE COMPLEX AND TRACKS DUE
EASTWARD THROUGH THE CAROLINAS AND MID ATLANTIC STATES BY DAYBREAK
WEDNESDAY. THE FORECAST AREA WILL BE LOCATED WITHIN THE WARM
SECTOR OF THE SYSTEM DURING THE DAYTIME HOURS TUESDAY...WITH
SOUTHERLY FLOW SUPPORTING TEMPERATURES RISING INTO THE UPPER 60S
NORTHWEST ZONES TO THE LOWER 70S SOUTH OF THE SAVANNAH RIVER. WITH
THE FORECAST AREA INITIALLY LOCATED SOUTH OF THE WARM FRONT AND
WEST OF THE APPROACHING COLD FRONT...EXPECT RAIN TO BE SLOW TO
PUSH INTO THE REGION THROUGH THE AFTERNOON HOURS. RAIN CHANCES
WILL THEN INCREASE SIGNIFICANTLY AFTER SUNSET ONCE THE FRONT AND
UPPER LOW PASS OVER THE SOUTHEAST AND MID ATLANTIC STATES. GIVEN
DECENT MODEL AGREEMENT IN POTENTIAL AND COVERAGE OF RAIN...HAVE
INCREASED POPS INTO THE LIKELY RANGE FOR MUCH OF THE FORECAST AREA
FROM AROUND MIDNIGHT TO DAYBREAK WEDNESDAY MORNING. THICK
INSULATING CLOUD COVER...ALONG WITH SOUTHERLY FLOW VEERING TO THE
WEST...WILL KEEP LOW TEMPERATURES TUESDAY NIGHT RATHER MILD IN THE
UPPER 40S TO LOWER 50S.
WEDNESDAY...THE STACKED AND INTENSIFYING LOW SYSTEM WILL LIFT
EAST/NORTHEAST DURING THE MORNING HOURS...WHILE THE TRAILING COLD
FRONT RAPIDLY MOVES OFFSHORE. RAIN CHANCES WILL BE DECREASING FROM
WEST TO EAST INTO THE EARLY AFTERNOON...AND WITH THE SURFACE LOW
DISPLACED NORTH OF THE FORECAST AREA BY DAYBREAK...WRAP AROUND
MOISTURE DOES NOT APPEAR TO BE A CONCERN AT THIS TIME. HIGH
TEMPERATURES WILL BE COOLER IN THE UPPER 50S TO LOWER 60S BEHIND
THE DEPARTING COLD FRONT...HOWEVER MODERATE TO STRONG
OFFSHORE/DOWNSLOPE FLOW AND LINGERING CLOUD COVER WILL MITIGATE
MORE SIGNIFICANT COOLING POTENTIAL. A GREATLY TIGHTENED PRESSURE
GRADIENT ON THE BACKSIDE OF THE SURFACE LOW...AS WELL AS COLD
ADVECTION ENHANCING MIXING INTO A 30 TO 40 KT LOW LEVEL
JET...SUGGESTS BREEZY TO GUSTY WEST WINDS DURING THE AFTERNOON
HOURS.
LAKE WINDS...WINDS WILL APPROACH ADVISORY CRITERIA TUESDAY
AFTERNOON AS A 40 KT LOW LEVEL JET PASSES OVER THE REGION.
HOWEVER...MIXING WILL BE LIMITED WITHIN A WARM ADVECTION REGIME
OVER THE COOLER LAKE WATERS. A BETTER CHANCE FOR LAKE WIND
ADVISORY THRESHOLDS TO BE MET IS ON WEDNESDAY...AS A SIGNIFICANTLY
TIGHTENED PRESSURE GRADIENT AND STRONG COLD ADVECTION ENHANCES
MIXING AND SUPPORTS 20 TO 25 KT WINDS OVER THE LAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS THE POTENT LOW SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH
THE LATE WEEK PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL
RIDGING WILL FOLLOW IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS
PREVAIL THURSDAY THROUGH THE WEEKEND. RISING HEIGHTS ALOFT WILL
SUPPORT A GRADUAL WARMING TREND THROUGH THE PERIOD...WITH
TEMPERATURES PEAKING IN THE LOW TO MID 60S THURSDAY AND
FRIDAY...THEN POSSIBLY THE LOW 70S SATURDAY AND SUNDAY. LOW
TEMPERATURES WILL ALSO MODERATE INTO THE UPPER 30S TO LOWER 40S BY
LATE PERIOD.
&&
.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF REDUCED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
THIS MORNING...WINDS REMAIN QUITE RISKY AT BUOY 41008 WHICH IS A
BIT HIGHER THAN THE LATEST RAP RUN. WILL EXTEND THE SMALL CRAFT
ADVISORY FOR BOTH GEORGIA LEGS UNTIL 8 AM.
TODAY...WINDS WILL SLOWLY SUBSIDE ACROSS THE MARINE AREA TODAY AS
COLD AIR ADVECTION STEADILY WANES. ONCE THE MORNING SURGE
CEASES...EXPECT WINDS TO SETTLE INTO THE 10-15 KT RANGE...EXCEPT
15-20 KT OVER THE GEORGIA OFFSHORE WATERS. SEAS WILL RANGE FROM
2-3 FT NEARSHORE WATERS AND 3-4 FT OFFSHORE WATERS
TONIGHT...ANOTHER SURGE LOOKS LIKELY OVER THE WATERS TONIGHT AS
THE PRESSURE GRADIENT TIGHTENS A BIT AHEAD OF HIGH PRESSURE
NUDGING IN FROM THE WEST. SHOULD SEE AT LEAST FREQUENT GUSTS TO 25
KT OCCUR OVER THE WARMER WATERS ACROSS THE EASTERN PORTIONS FOR
THE GEORGIA OFFSHORE LEG...SO A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED THERE. IT LOOKS A BIT MORE MARGINAL OVER THE NEARSHORE
WATERS SO WILL NOT HOIST AN ADVISORY JUST YET. SEAS WILL RANGE
FROM 2-4 FT NEARSHORE WATERS...4-6 FT OFFSHORE WATERS.
MONDAY...COLD ADVECTION WILL DIMINISH BY MID MORNING...AND ANY
SMALL CRAFT ADVISORIES SHOULD BE ALLOWED TO EXPIRE AT THAT TIME.
SOUTHERLY FLOW WILL THEN REMAIN BELOW ADVISORY THRESHOLDS FOR THE
REMAINDER OF THE DAY...AS HIGH PRESSURE BUILDS IN FROM FLORIDA AND
SETTLES OVER THE MARINE ZONES.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY...AS ATLANTIC HIGH PRESSURE SHIFTS FARTHER AWAY FROM
THE MARINE ZONES AHEAD OF AN INTENSIFYING LOW PRESSURE SYSTEM
MOVING INTO THE TENNESSEE VALLEY. THE POTENT LOW SYSTEM WILL
INTENSIFY AS IT SHIFTS INTO THE CAROLINAS LATE TUESDAY/EARLY
WEDNESDAY AND THEN OFF THE MID ATLANTIC COAST WEDNESDAY
NIGHT/THURSDAY. A TRAILING COLD FRONT WILL SWEEP THROUGH THE
MARINE ZONES LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. SMALL CRAFT
ADVISORY CRITERIA WILL BE REACHED BOTH AHEAD OF THE FRONT AND IN
ITS WAKE DURING THE MID WEEK PERIOD...WHILE THERE IS ALSO A GOOD
POTENTIAL FOR GALE CONDITIONS TO BE REACHED. WILL CONTINUE TO
MENTION THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR AMZ354-
374.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
409 AM EST SUN MAR 3 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT AND REMAIN
THROUGH EARLY THIS WEEK. LOW PRESSURE AND ITS TRAILING COLD FRONT
WILL IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
THE REGION WILL REMAIN UNDER THE INFLUENCE OF A DEEP LONGWAVE
TROUGH TODAY. THE TROUGH IS FORECAST TO GRADUALLY PUSH OFFSHORE AS
THE DAY PROGRESSES ALLOWING MID-LEVEL HEIGHTS TO STEADILY RISE IN
ITS WAKE. ALTHOUGH THE MID-LEVEL THERMAL ADVECTION PATTERN WILL
BECOME NEUTRAL TO SLIGHTLY POSITIVE LATER TODAY...H8 TEMPERATURES
OF -6 TO -7C WILL STILL KEEP HIGH TEMPERATURES ABOUT 10-15 DEGREES
BELOW NORMAL FOR EARLY MARCH. LOW-LEVEL THICKNESSES SCHEMES
SUPPORT HIGHS IN THE LOWER 50S WHICH LOOK REASONABLE PER MODEL
BUFR SOUNDINGS.
STEEP MID-LEVEL LAPSE RATES NEARING 6 C/KM COUPLED WITH SOME
LINGERING MID-LEVEL MOISTURE WILL LIKELY SUPPORT THE FORMATION OF
SOME SORT OF SHALLOW CUMULUS FIELD ONCE THE NOCTURNAL INVERSION
BURNS OFF. HOWEVER...IT IS UNCLEAR HOW EXTENSIVE THIS CLOUD DECK
WILL BECOME. BUFKIT CLOUD TOOLS SUGGEST A RATHER THICK 6 KFT CLOUD
LAYER WILL FORM...WHILE OTHER DATA SUCH AS THE WRF AND GEM
SIMULATED SATELLITE PRODUCTS SUPPORT CONSIDERABLY LESS CLOUD
COVER. CONSIDERING THE H9-H7 FLOW DOES NOT BECOME TRULY DOWNSLOPE
DOMINATED UNTIL MID-LATE AFTERNOON...SUSPECT THERE WILL BE ENOUGH
CLOUDS TO SUPPORT A PARTLY CLOUDY SKY CHARACTER...HOWEVER SKIES
RANGING ANYWHERE FROM CLOUDY TO COMPLETELY SUNNY ARE DISTINCT
POSSIBILITIES.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
TONIGHT...SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST
TONIGHT AS WEAK UPPER RIDGING OVER THE SOUTHERN PLAINS NUDGES
EAST. THERE LOOKS TO BE ENOUGH OF A RESIDUAL PRESSURE GRADIENT
ALONG THE EASTERN FLANKS OF THE SURFACE HIGH TO PREVENT FULL
BOUNDARY LAYER DECOUPLING AFTER SUNSET...EXCEPT OVER INTERIOR
SOUTHEAST GEORGIA WHERE DECOUPLING APPEARS MORE LIKELY. LOWS WILL
RANGE FROM THE UPPER 20S INLAND TO THE MID 30S AT THE BEACHES WITH
A FEW MID 20S LIKELY IN SOME SHELTERED AREAS OF FAR INTERIOR
SOUTHEAST GEORGIA.
MONDAY...SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT WILL
QUICKLY FOLLOW IN THE WAKE OF THE DEPARTING UPPER TROUGH EARLY IN
THE DAY. MODEL FORECAST SOUNDINGS INDICATE DEEP LAYER DRY AIR DURING
THE DAYTIME HOURS WITHIN A PREDOMINANT WEST/NORTHWEST FLOW. HIGH
LEVEL CLOUDS COULD THEN SHIFT INTO THE AREA OVERNIGHT DOWNSTREAM OF
A DEVELOPING LOW IN THE LOWER MISSISSIPPI/TENNESSEE VALLEYS. RISING
HEIGHTS ALOFT AND MOSTLY CLEAR TO PARTLY CLOUDY SKIES WILL SUPPORT
MODERATING TEMPERATURES...WITH HIGHS REACHING THE UPPER 50S TO LOWER
60S AWAY FROM THE LOCALLY COOLER COASTLINE. LOW LEVEL FLOW WILL BACK
TO THE SOUTHWEST OVERNIGHT...AND WITH EVIDENCE OF SOME HIGHER LEVEL
CLOUDS PROVIDING INSULATING EFFECTS AFTER MIDNIGHT...EXPECT LOW
TEMPERATURES TO BE NEARLY 10 DEGREES WARMER THAN THE PREVIOUS NIGHT.
LOWS WILL THUS RANGE FROM THE UPPER 30S INLAND TO THE LOWER 40S NEAR
THE BEACHES.
TUESDAY...A POTENT SHORTWAVE TROUGH WILL DESCEND FROM THE NORTHERN
PLAINS STATES INTO THE MID MISSISSIPPI VALLEY THROUGH THE AFTERNOON
HOURS...PROVIDING SIGNIFICANT ENERGY TO ORGANIZE AND INTENSIFY A
SURFACE LOW SYSTEM OVER THE TENNESSEE VALLEY BY SUNSET. THE UPPER
TROUGH WILL DEVELOP INTO A CUT OFF LOW OVERNIGHT...AT THE SAME TIME
THAT THE SURFACE SYSTEM BECOMES MORE COMPLEX AND TRACKS DUE
EASTWARD THROUGH THE CAROLINAS AND MID ATLANTIC STATES BY DAYBREAK
WEDNESDAY. THE FORECAST AREA WILL BE LOCATED WITHIN THE WARM
SECTOR OF THE SYSTEM DURING THE DAYTIME HOURS TUESDAY...WITH
SOUTHERLY FLOW SUPPORTING TEMPERATURES RISING INTO THE UPPER 60S
NORTHWEST ZONES TO THE LOWER 70S SOUTH OF THE SAVANNAH RIVER. WITH
THE FORECAST AREA INITIALLY LOCATED SOUTH OF THE WARM FRONT AND
WEST OF THE APPROACHING COLD FRONT...EXPECT RAIN TO BE SLOW TO
PUSH INTO THE REGION THROUGH THE AFTERNOON HOURS. RAIN CHANCES
WILL THEN INCREASE SIGNIFICANTLY AFTER SUNSET ONCE THE FRONT AND
UPPER LOW PASS OVER THE SOUTHEAST AND MID ATLANTIC STATES. GIVEN
DECENT MODEL AGREEMENT IN POTENTIAL AND COVERAGE OF RAIN...HAVE
INCREASED POPS INTO THE LIKELY RANGE FOR MUCH OF THE FORECAST AREA
FROM AROUND MIDNIGHT TO DAYBREAK WEDNESDAY MORNING. THICK
INSULATING CLOUD COVER...ALONG WITH SOUTHERLY FLOW VEERING TO THE
WEST...WILL KEEP LOW TEMPERATURES TUESDAY NIGHT RATHER MILD IN THE
UPPER 40S TO LOWER 50S.
WEDNESDAY...THE STACKED AND INTENSIFYING LOW SYSTEM WILL LIFT
EAST/NORTHEAST DURING THE MORNING HOURS...WHILE THE TRAILING COLD
FRONT RAPIDLY MOVES OFFSHORE. RAIN CHANCES WILL BE DECREASING FROM
WEST TO EAST INTO THE EARLY AFTERNOON...AND WITH THE SURFACE LOW
DISPLACED NORTH OF THE FORECAST AREA BY DAYBREAK...WRAP AROUND
MOISTURE DOES NOT APPEAR TO BE A CONCERN AT THIS TIME. HIGH
TEMPERATURES WILL BE COOLER IN THE UPPER 50S TO LOWER 60S BEHIND
THE DEPARTING COLD FRONT...HOWEVER MODERATE TO STRONG
OFFSHORE/DOWNSLOPE FLOW AND LINGERING CLOUD COVER WILL MITIGATE
MORE SIGNIFICANT COOLING POTENTIAL. A GREATLY TIGHTENED PRESSURE
GRADIENT ON THE BACKSIDE OF THE SURFACE LOW...AS WELL AS COLD
ADVECTION ENHANCING MIXING INTO A 30 TO 40 KT LOW LEVEL
JET...SUGGESTS BREEZY TO GUSTY WEST WINDS DURING THE AFTERNOON
HOURS.
LAKE WINDS...WINDS WILL APPROACH ADVISORY CRITERIA TUESDAY
AFTERNOON AS A 40 KT LOW LEVEL JET PASSES OVER THE REGION.
HOWEVER...MIXING WILL BE LIMITED WITHIN A WARM ADVECTION REGIME
OVER THE COOLER LAKE WATERS. A BETTER CHANCE FOR LAKE WIND
ADVISORY THRESHOLDS TO BE MET IS ON WEDNESDAY...AS A SIGNIFICANTLY
TIGHTENED PRESSURE GRADIENT AND STRONG COLD ADVECTION ENHANCES
MIXING AND SUPPORTS 20 TO 25 KT WINDS OVER THE LAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS THE POTENT LOW SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH
THE LATE WEEK PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL
RIDGING WILL FOLLOW IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS
PREVAIL THURSDAY THROUGH THE WEEKEND. RISING HEIGHTS ALOFT WILL
SUPPORT A GRADUAL WARMING TREND THROUGH THE PERIOD...WITH
TEMPERATURES PEAKING IN THE LOW TO MID 60S THURSDAY AND
FRIDAY...THEN POSSIBLY THE LOW 70S SATURDAY AND SUNDAY. LOW
TEMPERATURES WILL ALSO MODERATE INTO THE UPPER 30S TO LOWER 40S BY
LATE PERIOD.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF REDUCED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
THIS MORNING...WINDS REMAIN QUITE RISKY AT BUOY 41008 WHICH IS A
BIT HIGHER THAN THE LATEST RAP RUN. WILL EXTEND THE SMALL CRAFT
ADVISORY FOR BOTH GEORGIA LEGS UNTIL 8 AM.
TODAY...WINDS WILL SLOWLY SUBSIDE ACROSS THE MARINE AREA TODAY AS
COLD AIR ADVECTION STEADILY WANES. ONCE THE MORNING SURGE
CEASES...EXPECT WINDS TO SETTLE INTO THE 10-15 KT RANGE...EXCEPT
15-20 KT OVER THE GEORGIA OFFSHORE WATERS. SEAS WILL RANGE FROM
2-3 FT NEARSHORE WATERS AND 3-4 FT OFFSHORE WATERS
TONIGHT...ANOTHER SURGE LOOKS LIKELY OVER THE WATERS TONIGHT AS
THE PRESSURE GRADIENT TIGHTENS A BIT AHEAD OF HIGH PRESSURE
NUDGING IN FROM THE WEST. SHOULD SEE AT LEAST FREQUENT GUSTS TO 25
KT OCCUR OVER THE WARMER WATERS ACROSS THE EASTERN PORTIONS FOR
THE GEORGIA OFFSHORE LEG...SO A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED THERE. IT LOOKS A BIT MORE MARGINAL OVER THE NEARSHORE
WATERS SO WILL NOT HOIST AN ADVISORY JUST YET. SEAS WILL RANGE
FROM 2-4 FT NEARSHORE WATERS...4-6 FT OFFSHORE WATERS.
MONDAY...COLD ADVECTION WILL DIMINISH BY MID MORNING...AND ANY
SMALL CRAFT ADVISORIES SHOULD BE ALLOWED TO EXPIRE AT THAT TIME.
SOUTHERLY FLOW WILL THEN REMAIN BELOW ADVISORY THRESHOLDS FOR THE
REMAINDER OF THE DAY...AS HIGH PRESSURE BUILDS IN FROM FLORIDA AND
SETTLES OVER THE MARINE ZONES.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY...AS ATLANTIC HIGH PRESSURE SHIFTS FARTHER AWAY FROM
THE MARINE ZONES AHEAD OF AN INTENSIFYING LOW PRESSURE SYSTEM
MOVING INTO THE TENNESSEE VALLEY. THE POTENT LOW SYSTEM WILL
INTENSIFY AS IT SHIFTS INTO THE CAROLINAS LATE TUESDAY/EARLY
WEDNESDAY AND THEN OFF THE MID ATLANTIC COAST WEDNESDAY
NIGHT/THURSDAY. A TRAILING COLD FRONT WILL SWEEP THROUGH THE
MARINE ZONES LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. SMALL CRAFT
ADVISORY CRITERIA WILL BE REACHED BOTH AHEAD OF THE FRONT AND IN
ITS WAKE DURING THE MID WEEK PERIOD...WHILE THERE IS ALSO A GOOD
POTENTIAL FOR GALE CONDITIONS TO BE REACHED. WILL CONTINUE TO
MENTION THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST EARLY THIS MORNING FOR
AMZ354-374.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1208 AM EST SUN MAR 3 2013
.SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL PUSH EAST OF THE REGION OVERNIGHT
AND WILL BE FOLLOWED BY HIGH PRESSURE INTO EARLY IN THE UPCOMING
WEEK. A LOW PRESSURE SYSTEM AND ITS TRAILING COLD FRONT WILL
IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A LINGERING BATCH OF STRATOCUMULUS PERSISTS FROM THE CENTRAL
MIDLANDS INTO THE PEE DEE AND EXTENDING SOUTH INTO INTERIOR PARTS
OF SOUTHEAST SOUTH CAROLINA. RUC RH FIELDS SUGGEST THESE CLOUDS
WILL LINGER A BIT LONGER AS THEY SLOWLY PUSH EAST. THESE CLOUDS ARE
THINNING WITH TIME...SO STILL ANTICIPATE A DECENT AMOUNT OF
CLEARING TO OCCUR ACROSS THE NORTHERN ZONES PRIOR TO DAYBREAK.
ELSEWHERE...MOSTLY CLEAR SKIES WILL CONTINUE. OTHER THAN ADJUSTING
SKY COVER A BIT PER GOING TRENDS...NO MAJOR CHANGES WERE NEEDED TO
THE REMAINDER OF THE FORECAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
SUNDAY...ONE LAST SHORT WAVE WILL MOVE THROUGH THE LONG WAVE TROUGH
IN THE EST DURING MIDDAY AND THE AFTERNOON...KEEPING THE COOL AIR
MASS IN PLACE ACROSS THE LOW COUNTRY AND COASTAL EMPIRE. BUT WITH
CONSIDERABLE DRYING OF THE TROPOSPHERE AND PWATS NO MORE THAN 1/4 TO
1/3 INCH...THIS WILL RESULT IN NO MORE THAN SCATTERED TO PERHAPS
OCCASIONAL BROKEN STRATOCUMULUS CLOUDS AROUND 5K FEET. THE FORECAST
AREA WILL BE SITUATED IN A REGIME CAUGHT BETWEEN THE FAR EXTENSION
OF CYCLONIC CIRCULATION AROUND A DEEP RETROGRADING LOW OFF THE SE
CANADIAN MARITIMES...AND HIGH PRESSURE CENTERED IN THE NW GULF. THIS
WILL KEEP SOME PACKING TO THE PRESSURE GRADIENT TO ALLOW FOR NW
WINDS OF 10-20 MPH. COLD ADVECTION WILL DROP OFF BY LATE
MORNING...AND WITH MORE INSOLATION THAN WE EXPERIENCED TODAY WE
WON/T BE QUITE AS COOL. WE STAYED CLOSE TO THE 1000-850 MB THICKNESS
FORECAST...WHICH SUPPORTS 50-53 FOR HIGHS OR ABOUT 10-15F BELOW
CLIMATOLOGICAL NORMS.
SUNDAY NIGHT...THE EASTERN TROUGH LIFTS OUT ALOFT...WHILE AT THE
SURFACE THE INTENSE LOW WILL HEAD TOWARD COASTAL MAINE. THIS
CONTINUES TO BLOCK THE PROGRESSION OF THE GULF OF MEXICO HIGH
PRESSURE SYSTEM...AND PREVENTS TOTAL DECOUPLING UNTIL MAYBE VERY
LATE ACROSS OUR FAR SW ZONES. AS OUR GEOSTROPHIC WIND FIELDS DECLINE
TO NO LOWER THAN 10 OR 15 KT...IT LOOKS LIKE ANOTHER ADVECTIVE
FREEZE. FOR THAT REASON WE/LL SHOW MIN TEMPS OF 27-32 INLAND FROM
US-17...WITH MIDDLE 30S CLOSER TO THE COAST. THE CAVEAT BEING THAT
IF WINDS DO FULLY DECOUPLE THAT THE INLAND SECTIONS COULD BE A TAD
COLDER GIVEN CLEAR TO MOSTLY CLEAR SKIES.
MONDAY...RIDGING DEVELOPS ALOFT AND BRINGS WITH IT THE SURFACE
HIGH...WHOSE AXIS SLIPS INTO THE ATLANTIC BY LATE IN THE DAY. OTHER
THAN AN INCREASE IN JET STREAM CIRRUS COURTESY OF A 100 KT OR
GREATER SOUTHERN JET...SKIES WILL BE FAIRLY SUNNY. 850 MB TEMPS WILL
RISE TO BETWEEN 3C NORTH AND 6C SOUTH...WHILE LOW LEVEL THICKNESS
VALUES CLIMB A SOLID 25-30 METERS FROM THE PREVIOUS 24 HOURS. WE/LL
GAIN ABOUT 4-8 DEGREES ON OUR MAX TEMPS...BUT AGAIN WELL BELOW
TYPICAL EARLY MARCH THRESHOLDS.
TUESDAY...THE PROGRESSIVE PATTERN ALOFT WILL SEE THE TRANSITION FROM
RIDGING OVERHEAD IN THE MORNING BEING FORCED EAST IN THE
AFTERNOON...AS A POTENT SHORT WAVE /FOUND OFF THE PACIFIC NW
COASTLINE LATE SATURDAY/ DROPS INTO THE MID MS VALLEY. AS THIS
OCCURS...IT ALLOWS FOR BETTER ORGANIZATION TO A 1006 MB SURFACE LOW
THAT TREKS EAST AND NE INTO THE OH/TN VALLEYS. ASSOCIATED WITH THIS
FEATURE IS AN EAST-WEST ORIENTED WARM FRONT THAT WILL STRETCH ACROSS
NC...AND A NE-SW ALIGNED COLD FRONT THAT WILL REMAIN WEST OF THE
APPALACHIANS UNTIL IT CROSSES THE SOUTHERN BRANCH OF THAT CHAIN LATE
IN THE DAY. WHILE WE DO EXPERIENCE A STEADY CLIMB IN MOISTURE...THE
BEST LOW LEVEL FORCING AND DYNAMICS ALOFT REMAIN OFF TO THE WEST AND
NW. WE/LL TRIM BACK POPS INTO THE SLIGHT CHANCE RANGE FOR THE
AFTERNOON ALONG THE NW TIER OF COUNTIES. 850 MB TEMPS WILL RISE
ANOTHER 2-3C...ALONG WITH LOW LEVEL THICKNESS STRETCHING ANOTHER
20-30 METERS. COMBINED WITH A WARMING SW SYNOPTIC FLOW...WARM
ADVECTION WILL PUSH TEMPS UP TO AT LEAST 65-70 AWAY FROM THE COOLER
COASTAL COMMUNITIES. MEANWHILE...THERE IS A TIGHTENING OF THE
PRESSURE GRADIENT DURING THE AFTERNOON BETWEEN HIGH PRESSURE OFF THE
FL EAST COAST AND THE UPSTREAM LOW PRESSURE SYSTEM. THIS WILL
PRODUCE SW BREEZES OF A SOLID 15-25 MPH WITH HIGHER GUSTS.
LAKE WINDS...WE/LL BE CLOSE TO LAKE ADVISORY CRITERIA ON LAKE
MOULTRIE IN THE AFTERNOON AS A STEADILY TIGHTER GRADIENT WILL TAKE
HOLD. BUT SINCE THE LAKE TEMPS WILL ONLY BE IN THE LOWER 50S...THE
BEST MIXING WILL BE LIMITED TO THE SHORELINE LOCATIONS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS MORE INTENSE ENERGY ALOFT FLOWS INTO THE UPPER TROUGH...THE
FEATURE WILL LIKELY DEVELOP INTO A CUT OFF LOW...FURTHER
SUPPORTING THE DEEPENING OF THE SURFACE LOW AS IT PASSES DIRECTLY
OVER THE CAROLINAS TUESDAY NIGHT. THE ASSOCIATED COLD FRONT WILL
SWING THROUGH THE REGION DURING THE MORNING HOURS ON
WEDNESDAY...AND LIKELY BE QUICKLY OFFSHORE BY WEDNESDAY AFTERNOON.
THUS EXPECT THE BEST RAIN CHANCES TO OCCUR TUESDAY NIGHT INTO
EARLY WEDNESDAY MORNING...WITH PRECIPITATION ENDING FROM SOUTHWEST
TO NORTHEAST WEDNESDAY AFTERNOON FOLLOWING THE DEPARTING LOW
SYSTEM AND COLD FRONT. THICK CLOUD COVER AND WARM SOUTHERLY FLOW
AHEAD OF THE FRONT WILL KEEP LOW TEMPERATURES IN THE 40 DEGREE
RANGE TUESDAY NIGHT. TEMPERATURES ON WEDNESDAY WILL ONLY BE A FEW
DEGREES COOLER THAN THE PREVIOUS DAY DESPITE FRONTAL PASSAGE..WITH
HIGH TEMPERATURES COOLING JUST A FEW DEGREES. AS THE POTENT LOW
SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH THE LATE WEEK
PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL RIDGING WILL FOLLOW
IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS PREVAIL THURSDAY
THROUGH SATURDAY...WITH TEMPERATURES PEAKING IN THE LOW TO MID 60S
DURING THE AFTERNOON HOURS AND FALLING INTO THE UPPER 30S INLAND
TO LOWER 40S COASTLINE EACH NIGHT.
LAKE WINDS...A TIGHT PRESSURE GRADIENT ASSOCIATED WITH DEEP LOW
PRESSURE THAT MOVES FROM THE CENTRAL APPALACHIANS TO THE MID
ATLANTIC REGION...AND PERIODIC COLD ADVECTION IN WAKE OF A COLD
FRONT WILL IMPACT LAKE MOULTRIE. AS A RESULT..A LAKE WIND ADVISORY
APPEARS HIGHLY LIKELY DURING THE MIDDLE OF THE WEEK.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF LOWERED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
OVERNIGHT...W/NW WINDS 15-25 KT/SMALL CRAFT ADVISORIES WILL
CONTINUE ACROSS GA WATERS. ACROSS SC WATERS...CAPPED WINDS AT 20
KT WITHIN THE COLD ADVECTION PATTERN OVERNIGHT. SEAS WILL RANGE
FROM 2-4 FT WITHIN NEARSHORE WATERS TO 4-5 FT BEYOND 20 NM.
SUNDAY...ANY ONGOING SCA/S AT THE START OF THE DAY WILL QUICKLY COME
DOWN AS COLD ADVECTION WANES. OTHERWISE THERE IS STILL A GOOD 2-3 MB
SPREAD OF ISOBARS ACROSS THE WATERS...WHICH WILL KEEP NW WINDS UP IN
THE RANGE OF 13-18 KT AND GUSTY THROUGH THE BULK OF THE DAY. SEAS
WILL BE HELD TO MAINLY 2-3 FT WITHIN 20 NM OF THE COST AND 3-5 FT
FURTHER OUT DUE TO THE OFFSHORE FETCH.
SUNDAY NIGHT...ANOTHER SURGE OF COLD ADVECTION WILL TRIGGER THE
DEVELOPMENT OF SCA CONDITIONS YET AGAIN. WHILE IT IS MOST LIKELY
ACROSS AMZ374...THE NEAR SHORE LEGS COULD ALSO EXPERIENCE MARGINAL
SCA/S.
MONDAY...MORNING COLD ADVECTION DROPS OFF BY AROUND 15Z...AND THE
SCA FLAGS WILL COME DOWN OVER THE ATLANTIC COASTAL WATERS.
CONDITIONS WILL THEN QUIET DOWN FOR THE AFTERNOON...AS HIGH PRESSURE
BUILDS IN FROM FLORIDA AND SETTLES ATOP THE AREA.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY AS ATLANTIC HIGH PRESSURE GIVES TO AN UPSTREAM LOW
PRESSURE SYSTEM THAT MOVES INTO THE TN VALLEY. THAT LOW WILL THEN
SLOWLY INTENSIFY AS IT PASSES EAST OF THE MOUNTAINS TUESDAY
NIGHT...INTO NC ON WEDNESDAY...AND OFF THE MID ATLANTIC COAST
WEDNESDAY NIGHT/THURSDAY. A COLD FRONT TRAILING FROM THAT LOW WILL
SWEEP THROUGH THE MARINE COMMUNITY LATE TUESDAY NIGHT OR EARLY
WEDNESDAY. WE/LL MOST LIKELY HAVE THE NEED FOR AT LEAST SCA/S BOTH
PRE-FRONT AND POST-FRONT DURING THE MID WEEK PERIOD...BUT THERE IS
ALSO A FAIRLY DECENT SHOT OF GALE CONDITIONS DEVELOPING. WE/LL
CONTINUE TO MAINTAIN MENTION IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
AMZ354-374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
928 PM CST MON MAR 4 2013
.DISCUSSION...
753 PM CST
MADE A FEW MINOR ADJUSTMENTS TO THE FORECAST OVERNIGHT REGARDING
THE ONSET OF PRECIP. SCATTERED LIGHT SNOW SHOWERS ARE ACROSS
MINNESOTA...WISCONSIN...AND IOWA AHEAD OF THE LOW PRESSURE SYSTEM.
WITH SLIGHTLY DRIER AIR OVER NORTHERN IL...NOT EXPECTING MUCH
SNOWFALL FROM THESE SNOW SHOWERS AS THEY MOVE INTO OUR AREA. IN
FACT NUMEROUS AREAS UNDER THE REFLECTIVITIES TO OUR WEST ARE NOT
REPORTING ANY PRECIP AT THE SFC. REDUCED POPS TO SLIGHT CHANCE
THROUGH MIDNIGHT WITH LITTLE TO NO SNOW EXPECTED.
THE SYSTEM IS MOVING A LITTLE SLOWER THAN EARLIER THOUGHT SO ALSO
LOWERED POPS BTWN MIDNIGHT AND 3AM TO CHANCE OR LESS. HRRR AND OUR
IN HOUSE ARW BOTH INDICATE SNOW WILL NOT REACH CENTRAL IL UNTIL
LATE TONIGHT AFTER 3AM. DID NOT GO AS SLOW AS THEY INDICATED AS
THE ATMOSPHERE COULD BECOME MORE SATURATED BY LIGHT FLURRIES
OVERNIGHT.
OTHERWISE THE GOING FORECAST LOOKS ON TRACK WITH THE HEAVIEST
SNOWFALL STILL EXPECTED FROM TOMORROW MORNING THROUGH THE EVENING
HOURS. NO CHANGES WERE MADE TO THE WINTER STORM WARNING. TRAVEL
WILL BE SEVERELY IMPACTED BY SNOWFALL RATES OF 1-2 INCHES PER HOUR
AND LOW VISIBILITIES. WINDS INCREASE TOMORROW EVENING AND BLOWING
SNOW TUESDAY EVENING AND OVERNIGHT WILL LIKELY REDUCE VISIBILITIES
TO A QUARTER MILE OR LESS AT TIMES.
JEE
//PREV DISCUSSION...
315 PM CST
SHORT RANGE...TONIGHT THROUGH TUESDAY NIGHT...
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE REST OF MY
COUNTIES FOR LATE TONIGHT THROUGH TUESDAY EVENING.
NOT MUCH HAS CHANGED FROM THE PREVIOUS THINKING. THE LATEST WATER
VAPOR IMAGERY PLACES THE CENTER OF THIS SYSTEM ACROSS THE DAKOTAS
THIS AFTERNOON. WARM AIR ADVECTION/ISENTROPIC ASCENT AHEAD OF THIS
FEATURE HAS LEAD TO A WEAK BAND OF MAINLY LIGHT SNOW AND FLURRIES
ACROSS THE AREA THIS AFTERNOON. THIS HAS NOT AMOUNTED TO MUCH AND
LIKELY WILL NOT THROUGH THIS EVENING. THE MAIN SHOW WILL GET GOING
LATE TONIGHT AND ON TUESDAY. THE GUIDANCE HAS DISAGREEMENTS ON THE
EXACT TIMING OF THE ONSET OF PRECIP...WITH THE ECMWF AND NAM
SUGGESTING THAT THE SNOW MAY HOLD OFF UNTIL DAYBREAK. I DID BACK
OFF ON POPS A BIT TONIGHT TO ACCOUNT FOR A LATER ONSET...BUT STILL
MENTION LIKELY POPS TOWARDS DAYBREAK.
ONCE THINGS GET GOING TUESDAY MORNING...IT APPEARS THE SNOW INCREASE
IN INTENSITY THROUGH THE LATE MORNING AND DURING THE AFTERNOON.
IMPRESSIVE FORCING FOR ASCENT IS PROGGED TO SET UP IN THE DENDRITIC
GROWTH ZONE DURING THE AFTERNOON AS ISENTROPIC ASCENT INCREASES
AHEAD THE APPROACHING MID LEVEL SYSTEM. IT ALSO APPEARS THAT A TROWAL
LIKE STRUCTURE WILL DEVELOP ACROSS THE REGION DURING THE AFTERNOON
AS THE 700 MB LOW TRACKS SOUTHEASTWARD FROM EASTERN IOWA AND ACROSS
CENTRAL ILLINOIS. THIS WILL LIKELY LEAD TO A DECENT BAND OF MID
LEVEL FRONTOGENESIS FROM NORTH-NORTHWEST TO SOUTH-SOUTHEAST RIGHT
ACROSS THE CWA. AS IT TYPICAL WITH THIS TYPE OF SETUP...LOW STATIC
STABILITY SETS UP IN THE MID LEVELS DUE TO STEEP LAPSE RATES. LOOKS
TO SET UP THE INGREDIENTS FOR PERIODS OF HEAVY SNOW ACROSS THE AREA
DURING THE AFTERNOON WITH SNOW RATES OF 1 TO 1.5 INCHES AT TIMES.
I STILL DO HAVE SOME CONCERNS FOR PRECIPITATION TYPES ACROSS MY
SOUTHERN COUNTIES INITIALLY TUESDAY MORNING. GUIDANCE CONTINUES TO
SUGGEST THAT ENOUGH WARM AIR MAY BE SQUEEZED NORTHWARD ACROSS
CENTRAL ILLINOIS TO RESULT IN SOME RAIN OR SLEET AND SNOW MIX
THROUGH MID TO LATE MORNING. THEREAFTER...STRONG DYNAMIC COOLING
ASSOCIATED WITH MID LEVEL HEIGHT FALLS AND STRONG ASCENT...SHOULD
LEAD TO ALL SNOW DURING THE AFTERNOON. ALTHOUGH SNOW TO LIQUID
RATIOS MAY ONLY BE 10:1 FOR A PERIOD FAR SOUTH...IT APPEARS THAT
HEAVY SNOW COULD STILL RESULT IN 6 OR MORE INCHES ACROSS THESE
AREAS...AND THEREFORE HAVE INCLUDED THEM IN THE WARNING.
SOME OF THE GUIDANCE HAS SHIFTED THE HEAVIEST PRECIP AXIS JUST A TAD
SOUTH. HOWEVER...WITH LAKE ENHANCEMENT LIKELY TUESDAY AFTERNOON AND
EVENING...PERIODS OF HEAVY SNOW STILL APPEARS TO BE A GOOD BET
ACROSS FAR NORTHEAST ILLINOIS.
WINDS WILL INCREASE OUT OF THE NORTH-NORTHEAST LATE TUESDAY AFTERNOON
AND NIGHT AS THE LOW DEEPENS ACROSS THE OHIO VALLEY. THESE WINDS
COULD GUST UP TO 30-35 MPH...RESULTING IN SOME BLOWING AND DRIFTING
SNOW. I ADDED BLOWING SNOW AREA-WIDE BY TUESDAY EVENING TO ACCOUNT
FOR THIS.
SNOW SHOULD BEGIN TO TAPPER OFF FROM WEST TO EAST ACROSS THE AREA
DURING THE EVENING ON TUESDAY. HOWEVER...SOME MODERATE TO HEAVY SNOW
MAY CONTINUE INTO THE LATER EVENING HOURS...ESPECIALLY ACROSS
EASTERN ILLINOIS AND INTO INDIANA. HOWEVER...SNOWFALL RATES SHOULD
DROP OFF SIGNIFICANTLY AFTER 06 UTC ON WEDNESDAY...WITH ONLY SOME
LAKE EFFECT SNOW SHOWERS CONTINUING INTO WEDNESDAY.
KJB
LONGER RANGE...WEDNESDAY THROUGH NEXT MONDAY...
THE MAIN CONCERNS BEYOND THE EARLY WEEK WINTER STORM INCLUDE THE
POTENTIAL FOR SOME LINGERING LAKE EFFECT SNOW WEDNESDAY INTO EARLY
THURSDAY...THEN AFTER A COUPLE OF QUIET DAYS A WARM-UP WITH THE
POTENTIAL FOR RAIN ARRIVES LATER IN THE WEEKEND AND EARLY NEXT WEEK.
STRONG UPPER/SURFACE LOWS ASSOCIATED WITH THE DEPARTING WINTER STORM
SYSTEM SHOULD BE DIGGING WELL OFF TO OUR SOUTHEAST ACROSS THE
CENTRAL/SOUTHERN APPALACHIANS AND OFF THE MID-ATLANTIC COAST
WEDNESDAY. GUIDANCE DOES DEPICT A RAPIDLY SHEARING/WEAKENING
MID-LEVEL VORT MOVING ACROSS THE AREA DURING THE MORNING HOURS...
THOUGH OVERALL RISING HEIGHTS/DEVELOPING UPPER RIDGING IS INDICATED
WITH LOW LEVEL COLD ADVECTION AND DECREASING CYCLONIC CURVATURE.
THIS PRODUCES SUBSIDENCE AND DRYING ABOVE THE BOUNDARY LAYER... WITH
LITTLE/NO SYNOPTIC SCALE FORCING FOR LINGERING PRECIP. WITHIN THE
BOUNDARY LAYER HOWEVER...NORTH-NORTHEAST FLOW DOWN LAKE MICHIGAN
PRODUCES LONG FETCH AND FAIRLY STRONG MOISTURE-CONVERGENCE ALONG THE
WEST/SOUTHWEST SHORE. THERMODYNAMIC PROFILES BASED ON 12Z WRF-NAM
AND GFS SHOW RELATIVELY MARGINAL SETUP FOR ORGANIZED SNOW SHOWERS
HOWEVER...WITH 850 MB TEMPS ONLY AROUND -8/9C WEDNESDAY AND
WEDNESDAY NIGHT. THIS YIELDS WATER SFC TO 850 MB DELTA T VALUES
AROUND 12/13...WITH COMPUTED EQUILIBRIUM LEVELS LESS THAN 5000 FT
AGL. WHILE SUFFICIENT TO PRODUCE LAKE EFFECT CLOUDS AND LIGHT SNOW
SHOWERS...THESE PARAMETERS SUGGEST IT WOULD BE DIFFICULT TO GET ANY
SIGNIFICANT ACCUMULATION UNLESS SNOW BAND WERE STATIONARY FOR A LONG
PERIOD OF TIME. LOW LEVEL WIND PROFILES INDICATE THAT CONVERGENCE
WILL FAVOR THE ILLINOIS SHORE INTO LAKE COUNTY INDIANA THROUGH
WEDNESDAY EVENING...THUS HAVE INDICATED SOME MINOR ACCUMULATION OF A
FEW TENTHS OF AN INCH THERE. IF STRONGER THERMODYNAMICS WERE TO
OCCUR OR THE BAND WERE TO EXPERIENCE A HIGHER RESIDENCE TIME IN ANY
ONE LOCATION PERHAPS AN INCH OR TWO COULD ACCUMULATE...THOUGH
CONFIDENCE IN THAT OCCURRING IS VERY LOW. HIGH PRESSURE RIDGE
SPREADS EAST ACROSS THE MISSISSIPPI VALLEY LATER WEDNESDAY NIGHT AND
THURSDAY...WHICH LEADS TO WINDS WEAKENING AND VEERING NORTHEAST
THURSDAY MORNING AND THEN EAST LATER IN THE DAY WITH THERMODYNAMIC
SETUP ALSO WEAKENING RAPIDLY BEYOND THURSDAY MORNING.
PERIOD OF QUIET WEATHER IS THEN ANTICIPATED AS UPPER RIDGE BUILDS
ACROSS THE CENTRAL CONUS...AND SURFACE HIGH PRESSURE RIDGE MOVES
SLOWLY ACROSS THE AREA INTO FRIDAY. TEMPERATURES MODERATE BACK
TOWARD NORMAL...THOUGH DEEP SNOW COVER FROM EARLY WEEK STORM WILL
TEMPER THINGS FOR SEVERAL DAYS. BLEND OF 925-950 TEMPS AND MOS USED
FOR TEMPS...THOUGH LEANED TOWARD COOLER ECMWF MINS WHERE SKIES
ACCOUNT SNOW COVER.
BEYOND FRIDAY...GUIDANCE IN GENERALLY GOOD AGREEMENT IN CONTINUING
TO SLOWLY MOVE UPPER RIDGE EAST ACROSS THE REGION INTO
SATURDAY...WHILE DEVELOPING UPPER LOW OVER THE SOUTHWESTERN CONUS
AND THEN SLOWLY LIFTING IT NORTHEAST ACROSS THE PLAINS. NEW 12Z
ECMWF REALLY SLOWS THINGS DOWN OVER PREVIOUS RUNS...AND ENDS UP
CUTTING OFF THE LOW OVER THE HIGH PLAINS INTO EARLY NEXT WEEK WHILE
ITS PREVIOUS RUN AND OTHER GLOBAL GUIDANCE LIFT IT NORTHEAST ACROSS
THE REGION MONDAY. WHILE SLOWER MAY VERY WELL END UP BETTER...HAVE
BASED EXTENDED PART OF FORECAST ON BETTER CONSENSUS AND AWAY FROM
12Z ECMWF. OVERALL THIS SUGGEST PRECIP THREAT EVENTUALLY INCREASES
SATURDAY NIGHT/SUNDAY AND MONDAY AS OCCLUDING LOW MOVES THROUGH THE
AREA. THICKNESS FIELDS/SOUNDINGS SUGGEST THIS SHOULD MAINLY BE A
RAIN EVENT FOR OUR AREA...WITH TEMPS INTO THE 40S/LOWER 50S BY
SUNDAY/MONDAY. WILL HAVE TO MONITOR HYDRO ISSUES AS THIS STORM
APPROACHES...AS WE WILL BE MELTING OFF THE DEEP EARLY WEEK SNOW PACK
AND THEN POTENTIALLY RAINING 0.5-1.00 INCHES OF RAIN BY THE
SUNDAY/MONDAY TIMEFRAME.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* LIGHT SNOW EXPECTED TO DEVELOP AROUND/SOON AFTER DAYBREAK.
* SNOW INTENSITY INCREASES/VSBY FALLS MID/LATE MORNING...IFR VSBY
BECOMES LIKELY.
* HEAVIEST PERIOD OF SNOW APPROX 18-22Z AND POSSIBLY THROUGH
APPROX 01Z WITH 1/4-1/2SM VSBY LIKELY AND 1-1.5 INCH/HR SNOWFALL
RATES. LAKE ENHANCEMENT MAY HEEP HIGH INTENSITY SNOW GOING
THROUGH EARLY EVENING.
* EAST WINDS GUSTING TO NEAR 20 KT TUESDAY MORNING BECOMING
NORTHEAST THEN NORTH LATE TUESDAY AFTERNOON WITH GUSTS
INCREASING TO AROUND 25 KT.
* SNOW INTENSITY LOOKS TO EASE MID/LATE EVENING WITH VSBY
GRADUALLY IMPROVING.
MDB
//DISCUSSION...UPDATED 03Z...
MAIN CHALLENGE REMAINS TIMING/MAGNITUDE OF SNOW AT ONSET DURING
THE MORNING. CIGS CONTINUE TO LOWER AS WARM AND MOIST ASCENT
STARTS TO SPREAD INTO THE AREA. THIS LOWERING TREND WILL CONTINUE
THROUGH THE OVERNIGHT HOURS. NEW SHORT TERM GUIDANCE SLOWS ARRIVAL
OF ACCUMULATIONG SNOW BY A FEW HOURS BUT STILL SHOWS SIGNAL FOR
LOW LEVEL MOIST ASCENT...WHICH IS OCCURRING BASED ON CIG
TRENDS...WHICH DOES LOOK TO ALLOW PERSISTENT LIGHT SNOW TO DEVELOP
NEAR OR JUST AFTER DAYBREAK ACROSS THE AREA. THIS MAY BE PRETTY
LIGHT IN INTENSITY AND ALLOW FOR MINIMAL ACCUMULATION BUT MAY ALSO
BE ENOUGH TO PROVIDE VSBY REDUCTION. HAVE MADE MINIMAL IF ANY
ADJUSTMENT TO THE TAFS WITH CONFIDENCE IN THIS PARTICULAR PERIOD
STILL LOW BUT WITH ENOUGH SUPPORT TO KEEP SNOW MENTION EARLIER
RATHER THAN LATER. BY MID MORNING HAVE MUCH HIGHER CONFIDENCE IN
HEAVIER ACCUMULATION SNOW ARRIVING WITH THE AFTERNOON INTO EARLY
EVENING SEEING THE HEAVIEST SNOW AS DESCRIBED BELOW.
MDB
FROM 00Z...
VFR CONDITIONS PREVAIL AT THE MOMENT FOLLOWING THE PASSAGE OF A
BAND OF FORCING WHICH PRODUCED SOME LIGHT SNOW/FLURRIES. MAY SEE A
BREAK IN CLOUD COVER YET EARLY THIS EVENING BUT MVFR CLOUDS LOOK
TO QUICKLY SET IN MID/LATE EVENING. ANOTHER WAVE IS GENERATING
SOME FLURRIES/LIGHT SNOW FROM KMCW TO NEAR KMLI WHICH IS LIFTING
NORTHWARD. THIS MAY BRING SOME FLURRIES OR BRIEF LIGHT SNOW TO RFD
AND POSSIBLY THE CHI AREA TERMINALS THIS EVENING. OTHERWISE EAST
TO NORTHEAST WINDS WILL CONTINUE.
SNOW IS EXPECTED TO DEVELOP OUT TOWARDS RFD LATE TONIGHT AND
EXPAND EASTWARD INTO THE CHICAGO AREA AROUND OR SOON AFTER
DAYBREAK. INTENSITY LOOKS TO BE ON THE LIGHT SIDE FOR A FEW HOURS BUT
ENOUGH TO BRING MVFR VSBY BEFORE INTENSITY QUICKLY RAMPS UP
BRINGING IFR VSBY. HEAVIEST SNOW AND LOWEST VSBY LOOKS TO ARRIVE
AT RFD BY LATE MORNING AND IN THE CHICAGO AREA BY EARLY AFTERNOON.
EXPECT 1/4-1/2SM VSBY WITH SNOWFALL ACCUMULATION RATES OF 1-1.5
INCHES PER HOUR. SNOW INTENSITY WILL START TO EASE TOWARDS RFD
LATE IN THE AFTERNOON ALLOWING FOR SOME MODEST VSBY IMPROVEMENT
BEFORE THINGS WIND DOWN DURING THE MID/LATE EVENING. CHICAGO/NW
INDIANA HAS POTENTIAL FOR LAKE ENHANCEMENT OF SNOWFALL DURING THE
LATE AFTERNOON AND EARLY EVENING WHICH WOULD PROLONG THE HEAVIER
SNOWFALL AND 1/2-3/4SM OR LESS VSBY. CONFIDENCE IS LOWEST IN HOW
HEAVY SNOW WILL BE DURING THE LATE AFTERNOON AND EARLY EVENING BUT
ITS MORE OF A MATTER OF WHETHER VSBY IS DOWN AROUND 1/4SM OR UP IN
THE 3/4-1SM RANGE AS THERE IS GOOD CONFIDENCE IN SNOW ACCUMULATION
CONTINUING DURING THAT TIME. SNOW INTENSITY WILL THEN MORE QUICKLY
DIMINISH DURING THE MID/LATE EVENING.
THE OTHER ISSUE WILL BE WINDS. WIND DIRECTION WILL TURN NORTHEAST
THEN NORTH DURING THE LATE AFTERNOON WITH SPEEDS INCREASING.
EXPECT SUSTAINED SPEEDS OF 15-20 KT WITH GUSTS AROUND 25 KT AS
THIS OCCURS. THIS WILL LIKELY CAUSE BLOWING AND DRIFTING AND MAY
KEEP VSBY DOWN EVEN IF SNOW INTENSITY CAN EASE.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* MEDIUM CONFIDENCE IN SNOW DEVELOPING AROUND/SOON AFTER DAYBREAK
BUT LOW CONFIDENCE IN INTENSITY AND MAGNITUDE OF VSBY REDUCTION.
* HIGH CONFIDENCE IN SNOW INTENSITY INCREASING AND IFR VSBY
BECOMING LIKELY MID/LATE MORNING.
* HIGH CONFIDENCE IN HEAVIEST SNOW/LOWEST VSBY DURING THE
AFTERNOON...HIGH CONFIDENCE IN 1/4-1/2SM VSBY OCCURRING. LOW-
MEDIUM CONFIDENCE IN LAKE ENHANCEMENT POTENTIAL AND VSBY TRENDS
AFTER APPROX 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM-HIGH CONFIDENCE IN SNOW INTENSITY EASING MID/LATE TUESDAY
EVENING BUT LOW CONFIDENCE IN MAGNITUDE OF VSBY IMPROVEMENT.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...MVFR.
THURSDAY AND FRIDAY...VFR.
SATURDAY...SLIGHT CHANCE RAIN.
SUNDAY...SLIGHT CHANCE RAIN WITH HIGHER CHANCE SUNDAY NIGHT. MVFR
POSSIBLE SUNDAY NIGHT.
MDB
&&
.MARINE...
232 PM...LOW PRESSURE OVER THE SOUTHERN PLAINS WILL MOVE NORTHEAST
TO THE OHIO VALLEY TUESDAY MORNING AS IT ABSORBS A WEAKER AREA OF
LOW PRESSURE MOVING SOUTHEAST FROM THE DAKOTAS. THIS LOW WILL THEN
QUICKLY DEEPEN JUST OFF THE MID ATLANTIC COAST WEDNESDAY. AS THE
LOW APPROACHES...THE GRADIENT WILL TIGHTEN BETWEEN A LARGE RIDGE
OF HIGH PRESSURE OVER THE PLAINS AND SOUTHERN CANADA. NORTHERLY
WINDS WILL INCREASE TO 30 KTS BY TUESDAY AFTERNOON AND CONTINUE
INTO TUESDAY NIGHT. WINDS WILL SLOWLY DIMINISH WEDNESDAY NIGHT AS
THE RIDGE SPREADS ACROSS THE REGION THURSDAY. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-
ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO
MIDNIGHT WEDNESDAY.
WINTER STORM WARNING...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019
UNTIL MIDNIGHT WEDNESDAY.
IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019...3 AM
TUESDAY TO MIDNIGHT WEDNESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...3 AM TUESDAY TO 3 AM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
805 PM CST MON MAR 4 2013
.DISCUSSION...
753 PM CST
MADE A FEW MINOR ADJUSTMENTS TO THE FORECAST OVERNIGHT REGARDING
THE ONSET OF PRECIP. SCATTERED LIGHT SNOW SHOWERS ARE ACROSS
MINNESOTA...WISCONSIN...AND IOWA AHEAD OF THE LOW PRESSURE SYSTEM.
WITH SLIGHTLY DRIER AIR OVER NORTHERN IL...NOT EXPECTING MUCH
SNOWFALL FROM THESE SNOW SHOWERS AS THEY MOVE INTO OUR AREA. IN
FACT NUMEROUS AREAS UNDER THE REFLECTIVITIES TO OUR WEST ARE NOT
REPORTING ANY PRECIP AT THE SFC. REDUCED POPS TO SLIGHT CHANCE
THROUGH MIDNIGHT WITH LITTLE TO NO SNOW EXPECTED.
THE SYSTEM IS MOVING A LITTLE SLOWER THAN EARLIER THOUGHT SO ALSO
LOWERED POPS BTWN MIDNIGHT AND 3AM TO CHANCE OR LESS. HRRR AND OUR
IN HOUSE ARW BOTH INDICATE SNOW WILL NOT REACH CENTRAL IL UNTIL
LATE TONIGHT AFTER 3AM. DID NOT GO AS SLOW AS THEY INDICATED AS
THE ATMOSPHERE COULD BECOME MORE SATURATED BY LIGHT FLURRIES
OVERNIGHT.
OTHERWISE THE GOING FORECAST LOOKS ON TRACK WITH THE HEAVIEST
SNOWFALL STILL EXPECTED FROM TOMORROW MORNING THROUGH THE EVENING
HOURS. NO CHANGES WERE MADE TO THE WINTER STORM WARNING. TRAVEL
WILL BE SEVERELY IMPACTED BY SNOWFALL RATES OF 1-2 INCHES PER HOUR
AND LOW VISIBILITIES. WINDS INCREASE TOMORROW EVENING AND BLOWING
SNOW TUESDAY EVENING AND OVERNIGHT WILL LIKELY REDUCE VISIBILITIES
TO A QUARTER MILE OR LESS AT TIMES.
JEE
&&
.PREV DISCUSSION...
315 PM CST
SHORT RANGE...TONIGHT THROUGH TUESDAY NIGHT...
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE REST OF MY
COUNTIES FOR LATE TONIGHT THROUGH TUESDAY EVENING.
NOT MUCH HAS CHANGED FROM THE PREVIOUS THINKING. THE LATEST WATER
VAPOR IMAGERY PLACES THE CENTER OF THIS SYSTEM ACROSS THE DAKOTAS
THIS AFTERNOON. WARM AIR ADVECTION/ISENTROPIC ASCENT AHEAD OF THIS
FEATURE HAS LEAD TO A WEAK BAND OF MAINLY LIGHT SNOW AND FLURRIES
ACROSS THE AREA THIS AFTERNOON. THIS HAS NOT AMOUNTED TO MUCH AND
LIKELY WILL NOT THROUGH THIS EVENING. THE MAIN SHOW WILL GET GOING
LATE TONIGHT AND ON TUESDAY. THE GUIDANCE HAS DISAGREEMENTS ON THE
EXACT TIMING OF THE ONSET OF PRECIP...WITH THE ECMWF AND NAM
SUGGESTING THAT THE SNOW MAY HOLD OFF UNTIL DAYBREAK. I DID BACK
OFF ON POPS A BIT TONIGHT TO ACCOUNT FOR A LATER ONSET...BUT STILL
MENTION LIKELY POPS TOWARDS DAYBREAK.
ONCE THINGS GET GOING TUESDAY MORNING...IT APPEARS THE SNOW INCREASE
IN INTENSITY THROUGH THE LATE MORNING AND DURING THE AFTERNOON.
IMPRESSIVE FORCING FOR ASCENT IS PROGGED TO SET UP IN THE DENDRITIC
GROWTH ZONE DURING THE AFTERNOON AS ISENTROPIC ASCENT INCREASES
AHEAD THE APPROACHING MID LEVEL SYSTEM. IT ALSO APPEARS THAT A TROWAL
LIKE STRUCTURE WILL DEVELOP ACROSS THE REGION DURING THE AFTERNOON
AS THE 700 MB LOW TRACKS SOUTHEASTWARD FROM EASTERN IOWA AND ACROSS
CENTRAL ILLINOIS. THIS WILL LIKELY LEAD TO A DECENT BAND OF MID
LEVEL FRONTOGENESIS FROM NORTH-NORTHWEST TO SOUTH-SOUTHEAST RIGHT
ACROSS THE CWA. AS IT TYPICAL WITH THIS TYPE OF SETUP...LOW STATIC
STABILITY SETS UP IN THE MID LEVELS DUE TO STEEP LAPSE RATES. LOOKS
TO SET UP THE INGREDIENTS FOR PERIODS OF HEAVY SNOW ACROSS THE AREA
DURING THE AFTERNOON WITH SNOW RATES OF 1 TO 1.5 INCHES AT TIMES.
I STILL DO HAVE SOME CONCERNS FOR PRECIPITATION TYPES ACROSS MY
SOUTHERN COUNTIES INITIALLY TUESDAY MORNING. GUIDANCE CONTINUES TO
SUGGEST THAT ENOUGH WARM AIR MAY BE SQUEEZED NORTHWARD ACROSS
CENTRAL ILLINOIS TO RESULT IN SOME RAIN OR SLEET AND SNOW MIX
THROUGH MID TO LATE MORNING. THEREAFTER...STRONG DYNAMIC COOLING
ASSOCIATED WITH MID LEVEL HEIGHT FALLS AND STRONG ASCENT...SHOULD
LEAD TO ALL SNOW DURING THE AFTERNOON. ALTHOUGH SNOW TO LIQUID
RATIOS MAY ONLY BE 10:1 FOR A PERIOD FAR SOUTH...IT APPEARS THAT
HEAVY SNOW COULD STILL RESULT IN 6 OR MORE INCHES ACROSS THESE
AREAS...AND THEREFORE HAVE INCLUDED THEM IN THE WARNING.
SOME OF THE GUIDANCE HAS SHIFTED THE HEAVIEST PRECIP AXIS JUST A TAD
SOUTH. HOWEVER...WITH LAKE ENHANCEMENT LIKELY TUESDAY AFTERNOON AND
EVENING...PERIODS OF HEAVY SNOW STILL APPEARS TO BE A GOOD BET
ACROSS FAR NORTHEAST ILLINOIS.
WINDS WILL INCREASE OUT OF THE NORTH-NORTHEAST LATE TUESDAY AFTERNOON
AND NIGHT AS THE LOW DEEPENS ACROSS THE OHIO VALLEY. THESE WINDS
COULD GUST UP TO 30-35 MPH...RESULTING IN SOME BLOWING AND DRIFTING
SNOW. I ADDED BLOWING SNOW AREA-WIDE BY TUESDAY EVENING TO ACCOUNT
FOR THIS.
SNOW SHOULD BEGIN TO TAPPER OFF FROM WEST TO EAST ACROSS THE AREA
DURING THE EVENING ON TUESDAY. HOWEVER...SOME MODERATE TO HEAVY SNOW
MAY CONTINUE INTO THE LATER EVENING HOURS...ESPECIALLY ACROSS
EASTERN ILLINOIS AND INTO INDIANA. HOWEVER...SNOWFALL RATES SHOULD
DROP OFF SIGNIFICANTLY AFTER 06 UTC ON WEDNESDAY...WITH ONLY SOME
LAKE EFFECT SNOW SHOWERS CONTINUING INTO WEDNESDAY.
KJB
LONGER RANGE...WEDNESDAY THROUGH NEXT MONDAY...
THE MAIN CONCERNS BEYOND THE EARLY WEEK WINTER STORM INCLUDE THE
POTENTIAL FOR SOME LINGERING LAKE EFFECT SNOW WEDNESDAY INTO EARLY
THURSDAY...THEN AFTER A COUPLE OF QUIET DAYS A WARM-UP WITH THE
POTENTIAL FOR RAIN ARRIVES LATER IN THE WEEKEND AND EARLY NEXT WEEK.
STRONG UPPER/SURFACE LOWS ASSOCIATED WITH THE DEPARTING WINTER STORM
SYSTEM SHOULD BE DIGGING WELL OFF TO OUR SOUTHEAST ACROSS THE
CENTRAL/SOUTHERN APPALACHIANS AND OFF THE MID-ATLANTIC COAST
WEDNESDAY. GUIDANCE DOES DEPICT A RAPIDLY SHEARING/WEAKENING
MID-LEVEL VORT MOVING ACROSS THE AREA DURING THE MORNING HOURS...
THOUGH OVERALL RISING HEIGHTS/DEVELOPING UPPER RIDGING IS INDICATED
WITH LOW LEVEL COLD ADVECTION AND DECREASING CYCLONIC CURVATURE.
THIS PRODUCES SUBSIDENCE AND DRYING ABOVE THE BOUNDARY LAYER... WITH
LITTLE/NO SYNOPTIC SCALE FORCING FOR LINGERING PRECIP. WITHIN THE
BOUNDARY LAYER HOWEVER...NORTH-NORTHEAST FLOW DOWN LAKE MICHIGAN
PRODUCES LONG FETCH AND FAIRLY STRONG MOISTURE-CONVERGENCE ALONG THE
WEST/SOUTHWEST SHORE. THERMODYNAMIC PROFILES BASED ON 12Z WRF-NAM
AND GFS SHOW RELATIVELY MARGINAL SETUP FOR ORGANIZED SNOW SHOWERS
HOWEVER...WITH 850 MB TEMPS ONLY AROUND -8/9C WEDNESDAY AND
WEDNESDAY NIGHT. THIS YIELDS WATER SFC TO 850 MB DELTA T VALUES
AROUND 12/13...WITH COMPUTED EQUILIBRIUM LEVELS LESS THAN 5000 FT
AGL. WHILE SUFFICIENT TO PRODUCE LAKE EFFECT CLOUDS AND LIGHT SNOW
SHOWERS...THESE PARAMETERS SUGGEST IT WOULD BE DIFFICULT TO GET ANY
SIGNIFICANT ACCUMULATION UNLESS SNOW BAND WERE STATIONARY FOR A LONG
PERIOD OF TIME. LOW LEVEL WIND PROFILES INDICATE THAT CONVERGENCE
WILL FAVOR THE ILLINOIS SHORE INTO LAKE COUNTY INDIANA THROUGH
WEDNESDAY EVENING...THUS HAVE INDICATED SOME MINOR ACCUMULATION OF A
FEW TENTHS OF AN INCH THERE. IF STRONGER THERMODYNAMICS WERE TO
OCCUR OR THE BAND WERE TO EXPERIENCE A HIGHER RESIDENCE TIME IN ANY
ONE LOCATION PERHAPS AN INCH OR TWO COULD ACCUMULATE...THOUGH
CONFIDENCE IN THAT OCCURRING IS VERY LOW. HIGH PRESSURE RIDGE
SPREADS EAST ACROSS THE MISSISSIPPI VALLEY LATER WEDNESDAY NIGHT AND
THURSDAY...WHICH LEADS TO WINDS WEAKENING AND VEERING NORTHEAST
THURSDAY MORNING AND THEN EAST LATER IN THE DAY WITH THERMODYNAMIC
SETUP ALSO WEAKENING RAPIDLY BEYOND THURSDAY MORNING.
PERIOD OF QUIET WEATHER IS THEN ANTICIPATED AS UPPER RIDGE BUILDS
ACROSS THE CENTRAL CONUS...AND SURFACE HIGH PRESSURE RIDGE MOVES
SLOWLY ACROSS THE AREA INTO FRIDAY. TEMPERATURES MODERATE BACK
TOWARD NORMAL...THOUGH DEEP SNOW COVER FROM EARLY WEEK STORM WILL
TEMPER THINGS FOR SEVERAL DAYS. BLEND OF 925-950 TEMPS AND MOS USED
FOR TEMPS...THOUGH LEANED TOWARD COOLER ECMWF MINS WHERE SKIES
ACCOUNT SNOW COVER.
BEYOND FRIDAY...GUIDANCE IN GENERALLY GOOD AGREEMENT IN CONTINUING
TO SLOWLY MOVE UPPER RIDGE EAST ACROSS THE REGION INTO
SATURDAY...WHILE DEVELOPING UPPER LOW OVER THE SOUTHWESTERN CONUS
AND THEN SLOWLY LIFTING IT NORTHEAST ACROSS THE PLAINS. NEW 12Z
ECMWF REALLY SLOWS THINGS DOWN OVER PREVIOUS RUNS...AND ENDS UP
CUTTING OFF THE LOW OVER THE HIGH PLAINS INTO EARLY NEXT WEEK WHILE
ITS PREVIOUS RUN AND OTHER GLOBAL GUIDANCE LIFT IT NORTHEAST ACROSS
THE REGION MONDAY. WHILE SLOWER MAY VERY WELL END UP BETTER...HAVE
BASED EXTENDED PART OF FORECAST ON BETTER CONSENSUS AND AWAY FROM
12Z ECMWF. OVERALL THIS SUGGEST PRECIP THREAT EVENTUALLY INCREASES
SATURDAY NIGHT/SUNDAY AND MONDAY AS OCCLUDING LOW MOVES THROUGH THE
AREA. THICKNESS FIELDS/SOUNDINGS SUGGEST THIS SHOULD MAINLY BE A
RAIN EVENT FOR OUR AREA...WITH TEMPS INTO THE 40S/LOWER 50S BY
SUNDAY/MONDAY. WILL HAVE TO MONITOR HYDRO ISSUES AS THIS STORM
APPROACHES...AS WE WILL BE MELTING OFF THE DEEP EARLY WEEK SNOW PACK
AND THEN POTENTIALLY RAINING 0.5-1.00 INCHES OF RAIN BY THE
SUNDAY/MONDAY TIMEFRAME.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* LIGHT SNOW EXPECTED TO DEVELOP AROUND/SOON AFTER DAYBREAK.
* SNOW INTENSITY INCREASES/VSBY FALLS MID/LATE MORNING...IFR VSBY
BECOMES LIKELY.
* HEAVIEST PERIOD OF SNOW APPROX 18-22Z AND POSSIBLY THROUGH
APPROX 01Z WITH 1/4-1/2SM VSBY LIKELY AND 1-1.5 INCH/HR SNOWFALL
RATES. LAKE ENHANCEMENT MAY HEEP HIGH INTENSITY SNOW GOING
THROUGH EARLY EVENING.
* EAST WINDS GUSTING TO NEAR 20 KT TUESDAY MORNING BECOMING
NORTHEAST THEN NORTH LATE TUESDAY AFTERNOON WITH GUSTS
INCREASING TO AROUND 25 KT.
* SNOW INTENSITY LOOKS TO EASE MID/LATE EVENING WITH VSBY
GRADUALLY IMPROVING.
MDB
//DISCUSSION...UPDATED 00Z...
VFR CONDITIONS PREVAIL AT THE MOMENT FOLLOWING THE PASSAGE OF A
BAND OF FORCING WHICH PRODUCED SOME LIGHT SNOW/FLURRIES. MAY SEE A
BREAK IN CLOUD COVER YET EARLY THIS EVENING BUT MVFR CLOUDS LOOK
TO QUICKLY SET IN MID/LATE EVENING. ANOTHER WAVE IS GENERATING
SOME FLURRIES/LIGHT SNOW FROM KMCW TO NEAR KMLI WHICH IS LIFTING
NORTHWARD. THIS MAY BRING SOME FLURRIES OR BRIEF LIGHT SNOW TO RFD
AND POSSIBLY THE CHI AREA TERMINALS THIS EVENING. OTHERWISE EAST
TO NORTHEAST WINDS WILL CONTINUE.
SNOW IS EXPECTED TO DEVELOP OUT TOWARDS RFD LATE TONIGHT AND
EXPAND EASTWARD INTO THE CHICAGO AREA AROUND OR SOON AFTER
DAYBREAK. INTENSITY LOOKS TO BE ON THE LIGHT SIDE FOR A FEW HOURS BUT
ENOUGH TO BRING MVFR VSBY BEFORE INTENSITY QUICKLY RAMPS UP
BRINGING IFR VSBY. HEAVIEST SNOW AND LOWEST VSBY LOOKS TO ARRIVE
AT RFD BY LATE MORNING AND IN THE CHICAGO AREA BY EARLY AFTERNOON.
EXPECT 1/4-1/2SM VSBY WITH SNOWFALL ACCUMULATION RATES OF 1-1.5
INCHES PER HOUR. SNOW INTENSITY WILL START TO EASE TOWARDS RFD
LATE IN THE AFTERNOON ALLOWING FOR SOME MODEST VSBY IMPROVEMENT
BEFORE THINGS WIND DOWN DURING THE MID/LATE EVENING. CHICAGO/NW
INDIANA HAS POTENTIAL FOR LAKE ENHANCEMENT OF SNOWFALL DURING THE
LATE AFTERNOON AND EARLY EVENING WHICH WOULD PROLONG THE HEAVIER
SNOWFALL AND 1/2-3/4SM OR LESS VSBY. CONFIDENCE IS LOWEST IN HOW
HEAVY SNOW WILL BE DURING THE LATE AFTERNOON AND EARLY EVENING BUT
ITS MORE OF A MATTER OF WHETHER VSBY IS DOWN AROUND 1/4SM OR UP IN
THE 3/4-1SM RANGE AS THERE IS GOOD CONFIDENCE IN SNOW ACCUMULATION
CONTINUING DURING THAT TIME. SNOW INTENSITY WILL THEN MORE QUICKLY
DIMINISH DURING THE MID/LATE EVENING.
THE OTHER ISSUE WILL BE WINDS. WIND DIRECTION WILL TURN NORTHEAST
THEN NORTH DURING THE LATE AFTERNOON WITH SPEEDS INCREASING.
EXPECT SUSTAINED SPEEDS OF 15-20 KT WITH GUSTS AROUND 25 KT AS
THIS OCCURS. THIS WILL LIKELY CAUSE BLOWING AND DRIFTING AND MAY
KEEP VSBY DOWN EVEN IF SNOW INTENSITY CAN EASE.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM-HIGH CONFIDENCE IN SNOW DEVELOPING AROUND/SOON AFTER DAYBREAK.
* HIGH CONFIDENCE IN SNOW INTENSITY INCREASING AND IFR VSBY
BECOMING LIKELY MID/LATE MORNING.
* HIGH CONFIDENCE IN HEAVIEST SNOW/LOWEST VSBY DURING THE
AFTERNOON...HIGH CONFIDENCE IN 1/4-1/2SM VSBY OCCURRING. LOW-
MEDIUM CONFIDENCE IN LAKE ENHANCEMENT POTENTIAL AND VSBY TRENDS
AFTER APPROX 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM-HIGH CONFIDENCE IN SNOW INTENSITY EASING MID/LATE TUESDAY
EVENING BUT LOW CONFIDENCE IN MAGNITUDE OF VSBY IMPROVEMENT.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...MVFR.
THURSDAY AND FRIDAY...VFR.
SATURDAY...SLIGHT CHANCE RAIN.
SUNDAY...SLIGHT CHANCE RAIN WITH HIGHER CHANCE SUNDAY NIGHT. MVFR
POSSIBLE SUNDAY NIGHT.
MDB
&&
.MARINE...
232 PM...LOW PRESSURE OVER THE SOUTHERN PLAINS WILL MOVE NORTHEAST
TO THE OHIO VALLEY TUESDAY MORNING AS IT ABSORBS A WEAKER AREA OF
LOW PRESSURE MOVING SOUTHEAST FROM THE DAKOTAS. THIS LOW WILL THEN
QUICKLY DEEPEN JUST OFF THE MID ATLANTIC COAST WEDNESDAY. AS THE
LOW APPROACHES...THE GRADIENT WILL TIGHTEN BETWEEN A LARGE RIDGE
OF HIGH PRESSURE OVER THE PLAINS AND SOUTHERN CANADA. NORTHERLY
WINDS WILL INCREASE TO 30 KTS BY TUESDAY AFTERNOON AND CONTINUE
INTO TUESDAY NIGHT. WINDS WILL SLOWLY DIMINISH WEDNESDAY NIGHT AS
THE RIDGE SPREADS ACROSS THE REGION THURSDAY. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-
ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO
MIDNIGHT WEDNESDAY.
WINTER STORM WARNING...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-
ILZ019...MIDNIGHT TUESDAY TO MIDNIGHT WEDNESDAY.
IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019...3 AM
TUESDAY TO MIDNIGHT WEDNESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...3 AM TUESDAY TO 3 AM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1127 PM CST SAT MAR 2 2013
.DISCUSSION...
821 PM CST
MADE SOME MINOR ADJUSTMENTS TO FORECAST/GRIDS. WEAK LAKE EFFECT
SNOW BAND HAS DRIFTED WEST TO THE ILLINOIS SHORE SO HAVE ADDED
SOME SMALL POPS FOR LIGHT SNOW SHOWERS. LATEST SHORT TERM
GUIDANCE FROM HRRR AND RAP WOULD SUGGEST WEAK CONVERGENCE ZONE
WILL REMAIN DOWN CENTER-WEST SIDE OF LAKE OVERNIGHT. MAIN BAND
WILL BE COMING INTO NORTHWEST INDIANA BUT AS THE BAND
MEANDERS...SOME LIGHT SNOW COULD FALL ALONG THE ILLINOIS SHORE AT
TIMES. BUFKIT INDICATES MARGINAL TEMPERATURES BUT SHALLOW CLOUD
DEPTH...SO AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION...
PERHAPS A FEW TENTHS OF AN INCH IN NORTHWEST IN.
THE OTHER CONCERN IS TEMPERATURES. WITH CLEAR SKIES AWAY FROM THE
LAKE...LIGHT WINDS AND FRESH SNOWPACK...TEMPS COULD GET INTO THE
SINGLE DIGITS ACROSS THE NORTH SUBURBS WHERE SNOW COVER IS
DEEPEST. ALREADY SEEING SINGLE DIGITS AND LOW TEENS IN SRN WI AT
THIS HOUR.
ALLSOPP
//PREV DISCUSSION...
332 PM CST
MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LINGERING LAKE EFFECT
SNOW SHOWERS ACROSS NORTHWEST INDIANA TONIGHT INTO EARLY SUNDAY
MORNING...BUT OF MORE IMPORTANCE ARE THE INCREASED PROBABILITIES
FOR A SIGNIFICANT SNOW ACCUMULATION FOR A GOOD PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT.
LATEST RADAR IMAGERY DEPICTING PERSISTENT LAKE EFFECT SNOW SHOWERS
FOR AREAS ACROSS NORTHEAST ILLINOIS AND NORTHWEST
INDIANA...PRIMARILY EAST OF INTERSTATE 57 LATE THIS AFTERNOON. A
MORE BROAD AREA OF LIGHT SNOW HAD DEVELOPED WITH A BETTER BAND
NOTED PUSHING SOUTH INTO LAKE/PORTER COUNTIES EARLIER TODAY.
VISIBILITY AND ISOLATED SLIPPERY CONDITIONS HAVE BEEN A CONCERN
BUT A SAVING GRACE HAS BEEN THE RELATIVELY WARMER CONDITIONS AT
AROUND FREEZING. THIS HAS ALLOWED FOR MOST OF THE MAJOR HIGHWAYS
TO REMAIN ONLY WET...PER TRAFFIC CAMS ACROSS NORTHWEST INDIANA.
ALTHOUGH IN THE NEAR TERM...HAVE NOTICED A DIMINISHING TREND WITH
THE OVERALL DEVELOPMENT AS WELL AS THE STRONGER MORE DEFINED BAND
IN INDIANA. THIS IS IN RESPONSE TO THE LOSS OF THE CONVERGENCE
ALONG THE SOUTHERN END OF THE LAKE AS WELL AS SOME MODERATING
THERMODYNAMIC CONDITIONS ACROSS THE ENTIRE LAKE. DONT FEEL AS IF
OUR CWA IS COMPLETELY THROUGH WITH OBSERVING SOME LAKE EFFECT SNOW
TONIGHT INTO SUNDAY MORNING DESPITE BOUNDARY LAYER FLOW SHIFTING
MORE NORTH/NORTHWEST THIS EVENING. COLDER AIR CURRENTLY WORKING
ITS WAY SOUTH DOWN THE LAKE WILL CONTINUE TONIGHT REINFORCING
DELTA TS OVER THE LENGTH OF THE LAKE. THIS COINCIDING WITH A LONG
FETCH AS WELL AS SHORT RANGE GUIDANCE INDICATING THAT BETTER LOW
LEVEL FORCING/CONVERGENCE WILL RETURN BACK TO THE CWA AFTER THE
9PM TIME FRAME TONIGHT...DO EXPECT REDEVELOPMENT OF SNOW SHOWERS
BUT PRIMARILY FOR LAKE AND PORTER COUNTIES IN INDIANA. SO HAVE
INCREASED POPS TONIGHT ACROSS THESE AREAS AND HAVE INCLUDED
ADDITIONAL SNOW ACCUMULATION OF A COUPLE OF INCHES...WHICH SEEMS
PROBABLE WITH COLDER TEMPS EXPECTED TONIGHT. THE REMAINDER OF THE
CWA WILL OBSERVE QUIET AND MOSTLY CLEAR SKIES TONIGHT...OUTSIDE OF
A FEW PASSING HIGH LEVEL CLOUDS. ALSO DO EXPECT A CHILLY NIGHT
WITH LOW TEMPS IN THE TEENS EXPECTED ACROSS MOST OF THE
CWA...OUTSIDE OF LAKE EFFECT CLOUD COVER IN NORTHWEST INDIANA.
FAIRLY SIMILAR CONDITIONS ARE EXPECTED ACROSS THE LAKE SUNDAY
MORNING...WITH LAKE EFFECT SNOW STILL AFFECTING PRIMARILY PORTER
COUNTY. DONT EXPECT MUCH IN TERMS OF ACCUMULATION AS BETTER
DEVELOPMENT SHOULD BE JUST EAST OF PORTER COUNTY...WITH BOUNDARY
LAYER FLOW CONTINUING TO SHIFT AND CONDITIONS OVER THE LAKE
BECOMING LESS FAVORABLE. SKIES WILL BE CLEARING FOR ALL OF THE CWA
ON SUNDAY AS VORT MAX SLIDES SOUTHEAST OF THE AREA AND RISING
HEIGHTS ALOFT USHER IN A SURFACE RIDGE. WITH A WARM MARCH SUN AND
A MODERATING TEMP PROFILE...RELATIVELY PLEASANT CONDITIONS IN THE
LOW TO MID 30S WILL BE OBSERVED. ALTHOUGH...DO EXPECT THIS TO BE
RATHER BRIEF AS FOCUS THEN SHIFTS TOWARDS THE APPROACHING SYSTEM
FOR THE START OF THE WEEK.
AS WAS MENTIONED ABOVE...AM GETTING A LITTLE MORE CONCERNED AT THE
POSSIBILITY FOR A SIGNIFICANT SNOWFALL ACROSS A PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT. THE SYSTEM WHICH WE HAVE
CONTINUED TO MONITOR OVER THE LAST SEVERAL DAYS HAS STARTED TO
BECOME MORE CONSISTENT AMONG VARIOUS MODEL GUIDANCE. DESPITE THE
FACT THAT THERE ARE STILL SOME TIMING AND EXACT PLACEMENT
ISSUES...CONSENSUS IS GROWING FOR A STRONG SYSTEM TO AFFECT
NORTHERN ILLINOIS AND NORTHWEST INDIANA. A STRONG UPPER LEVEL
SYSTEM IS STILL FORECAST TO SLIDE ACROSS THE NORTHERN PLAINS BY
MONDAY...THEN QUICKLY DIG SOUTHEAST TOWARDS THE MID MISSISSIPPI
VALLEY MONDAY NIGHT INTO TUESDAY. WAA OUT AHEAD OF THIS SYSTEM
WILL SLOWLY BRING PRECIP ACROSS PRIMARILY THE SOUTHWEST PORTIONS
OF THE CWA DURING THE DAY ON MONDAY. WITH SLIGHT WARMING...A MIX
OF LIGHT RAIN OR SNOW WILL BE POSSIBLE FOR AREAS ACROSS THE
SOUTHERN CWA...BUT WITH LIGHT SNOW EXPECTED FURTHER NORTHWEST.
ALTHOUGH...REALLY NOT ANTICIPATING MUCH IN TERMS OF ANY
ACCUMULATION THROUGH MOST OF MONDAY WITH RELATIVELY WARMER TEMPS
IN PLACE. ITS NOT UNTIL LATE MONDAY NIGHT INTO TUESDAY THAT MORE
WIDESPREAD DEVELOPMENT WILL SHIFT EAST ACROSS THE CWA. DO EXPECT
ALL SNOW FOR THIS INITIAL TIME FRAME WITH LARGE SCALE LIFT RAPIDLY
COOLING THE TEMP PROFILE ACROSS THE AREA. LARGE SCALE FORCING
INCREASES...AND REALLY GETS GOING ON TUESDAY AS THIS UPPER LEVEL
LOW SHIFTS SOUTHEAST AND THE CWA LIKELY OBSERVES PERIODS OF
PERSISTENT WAA...WITH LIKELY AREAS OF DEFORMATION TO PIVOT ACROSS
THE CWA. ABUNDANT MOISTURE WILL BE PRESENT AND IS SEEN WITH THE
QPF THAT MODEL GUIDANCE IS DEVELOPING...WHICH SEEMS LIKE A VALID
SOLUTION GIVEN THE STRENGTH OF THIS DYNAMIC SYSTEM. WIDESPREAD
SNOW ACCUMULATION IS APPEARING MORE PROBABLE ACROSS THE ENTIRE CWA
TUESDAY INTO TUESDAY NIGHT AND AT THIS TIME...MORE SIGNIFICANT
SNOWFALL POSSIBLY IN EXCESS OF 6 INCHES IS PROBABLE FOR AREAS
SOUTH OF INTERSTATE 80. THIS SYSTEM WILL DEFINITELY NEED TO BE
MONITORED WITH SUCCESSIVE FORECASTS AS GUIDANCE COULD CONTINUE TO
VARY. NONETHELESS...IT IS APPEARING THAT THE REGION AND A PORTION
OF OUR AREA IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA COULD
OBSERVE A SIGNIFICANT SNOW ACCUMULATION WITH WIDESPREAD IMPACTS
LATE MONDAY NIGHT INTO TUESDAY NIGHT. GIVEN THE TIME RANGE OF THE
EVENT AND POSSIBLE RANGE OF SOLUTIONS...HAVE HELD OFF ON ANY
HEADLINES BUT WILL CONTINUE TO MONITOR THIS POTENTIAL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NONE
BMD
//DISCUSSION...UPDATED 06Z...
QUIET VFR PERIOD EXPECTED THROUGH MONDAY NIGHT. A RIDGE AXIS LIES
JUST WEST OF THE MISSISSIPPI RIVER TONIGHT AND WILL SLOWLY
TRANSITION EAST AND WILL MOVE ACROSS THE CHICAGO AREA SUNDAY
EVENING. AS THIS OCCURS...LIGHT NORTHERLY WIND WILL PREVAIL WITH
MOSTLY CLEAR SKIES. THERE ARE SOME LAKE EFFECT CLOUDS AT THE
SOUTHERN END OF LAKE MICHIGAN BUT SHOULD STAY EAST OF GYY. ONCE THE
RIDGE AXIS SLIDES OVERHEAD...EXPECT WINDS TO BEGIN TO TREND TO
SOUTHEASTERLY SUNDAY NIGHT INTO EARLY MONDAY AS LOW PRESSURE TAKES
SHAPE OVER THE CENTRAL PLAINS. THERE MAY ALSO BE AN INCREASE IN MID
AND HIGH LEVEL CLOUDINESS TOWARDS THE END OF THE TAF PERIOD.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...INCREASING SNOW AND MVFR CHANCES MONDAY NIGHT.
TUESDAY...SNOW AND IFR LIKELY.
WEDNESDAY...LINGERING LIGHT SNOW/MVFR BECOMING VFR.
THURSDAY AND FRIDAY...VFR.
MDB
&&
.MARINE...
400 PM CST
NORTH WINDS WILL CONTINUE TO GRADUALLY DIMINISH TO A MODERATE
BREEZE TONIGHT AND SUNDAY AS A RIDGE OF HIGH PRESSURE EXTENDING
FROM HUDSON BAY TO THE SOUTHERN PLAINS MOVES SLOWLY EASTWARD...
REACHING LAKE SUPERIOR...EASTERN WISCONSIN AND ILLINOIS...AND
THE LOWER OHIO VALLEY BY SUNDAY NIGHT. LIGHT BREEZES WILL
INCREASE TO MODERATE NORTHEAST AND EAST BREEZES DURING MONDAY
AND MONDAY NIGHT AS LOW PRESSURE MOVES EAST ACROSS THE CENTRAL
PLAINS TO THE LOWER OHIO VALLEY. AS THE LOW CONTINUES MOVING
OFF TO THE EAST MONDAY NIGHT THROUGH WEDNESDAY WINDS ON LAKE MI
WILL BACK TO OUT OF THE NORTHEAST AND NORTH WHILE FRESHENING TO
STRONG BREEZES. DURING WEDNESDAY AND WEDNESDAY ANOTHER RIDGE OF
HIGH PRESSURE WILL BE MOVING EAST TO ONTARIO... THE UPPER GREAT
LAKES...AND THE MID AND LOWER MS VALLEY ALLOWING WINDS TO
GRADUALLY SLACKEN TO A LIGHT BREEZE AGAIN.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 PM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
922 PM CST MON MAR 4 2013
.UPDATE...
JUST SENT AN UPDATE TO LOWER POPS WEST BY A CATEGORY FOR THE REST
OF THE THIS EVENING. THE PRECIP HAS BEEN SLOWER TO EVOLVE THAN
PREVIOUSLY EXPECTED AND IT NOW LOOKS LIKE ANY SIGNIFICANT
PRECIP/SNOW SHOULD NOT BEGIN UNTIL AFTER MIDNIGHT. REGIONAL RADAR
COMPOSITES WERE SHOWING AN EXPANSION OF LIGHT RETURNS OVER WESTERN
IOWA THE PAST HOUR BETWEEN SOME HIGHER REFLECTIVITY/S MOVING
NORTHEAST OUT OF NORTH CENTRAL MO MORE SHOWERY LOOKING PRECIP FROM
NORTHERN IA INTO MN. THE CURRENT THINKING IS THE NORTHERN MO/IA
AREAS WILL MERGE THE NEXT FEW HOURS WITH THE BETTER FORCING AHEAD
OF THE NORTHERN PLAINS UPPER LOW MOVING IN.
NO OTHER CHANGES WERE MADE TO THE FORECAST CONCERNING SNOW FALL
AMOUNTS OR HEADLINES. THE 00Z NAM CAME IN WITH AN UPPER LOW TRACK
NORTHEAST OF THE MONDAYS RUNS SUGGESTING LOWER SNOW AMOUNTS...BUT
THE NAM HAS BEEN A NORTHEASTERN OUTLIER WITH THIS SYSTEM ON SEVERAL
RUNS. THE LATEST RAP RUNS CONTINUE TO MOVE THE UPPER LOW ALONG A
SIMILAR TRACK AS MONDAY/S MODEL RUNS SUGGESTED.
DLF
&&
.PREV DISCUSSION... /ISSUED 625 PM CST MON MAR 4 2013/
AVIATION...
A SURFACE TROF WILL DEVELOP OVER THE AREA OVERNIGHT AND THEN MOVE
SOUTH INTO MISSOURI BY LATE TUESDAY AFTERNOON. WIDESPSREAD SNOWS
ARE EXPECTED TO SPREAD OVER THE AREA TONIGHT WITH THE DEVELOPING
TROF THEN TAPER OFF TUESDAY AFTERNOON. NORTH TO NORTHWEST WINDS
WILL INCREASE LATE TUESDAY MORNING AND INTO THE AFTERNOON WITH
GUSTS AROUND 25KTS ESPECIALLY WEST OF THE MISSISSIPPI RIVER.
GENERALLY VFR WITH SOME PATCHY MVFR CIGS NORTH THIS EVENING WILL
GRADUALLY DETERIORATE BY LATE EVENING WITH WIDESPREAD MVFR CIGS IN
THE 1KFT TO 2KFT RANGE BY MIDNIGHT. SOME SCATTERED SNOW SHOWERS
NORTH OR RAIN/SNOW SHOWERS SOUTH ARE POSSIBLE DURING THE EVENING.
BY LATE EVENING IFR CIGS WILL BE POSSIBLE IN EAST CENTRAL IA.
AFTER MIDNIGHT COUNTDOWNS WILL RAPIDLY DETERIORATE TO IFR AND
LIFR AS THE SNOW SPREADS OVER THE AREA. THE LOWEST CONDITIONS WILL
LIKELY OCCUR BETWEEN 09Z AND 18Z DUE OBSCURED CEILINGS AND
MODERATE TO HEAVY SNOW REDUCING VISIBILITIES TO A HALF MILE OR
LESS AT TIMES. WINDS DURING THIS TIME WILL BE LIGHT.
THE SNOW SHOULD BE TAPERING OFF SOME DURING THE AFTERNOON BUT
NORTH TO NORTHWEST WINDS WILL BE INCREASING CAUSING CONSIDERABLE
BLOWING SNOW WHICH WILL CONTRIBUTE TO VISIBILITIES STAYING AROUND
A MILE THROUGH THE AFTERNOON.
DLF
PREV DISCUSSION... /ISSUED 352 PM CST MON MAR 4 2013/
DISCUSSION...
SHORT TERM...ASSESSING A PLETHORA OF PARAMETERS ON MANY OF THE
VARIOUS 12Z RUN MODELS...IT IS APPARENT THAT THERE IS SOMEWHAT
SOUTHWESTWARD ADJUSTMENT OF THE MID LEVEL LOW AS WELL AS LOW TO
MID LEVEL FORCING ALONG THE INCOMING VORT GRADIENT FLANK TARGETING
AREAS FROM NEAR VINTON IOWA...SOUTHEASTWARD TO THE NORTHERN QUAD
CITIES...AND THEN PUSHING EASTWARD ALONG THE I-80 CORRIDOR EAST OF
THE QUAD CITIES LATE TONIGHT AND TUESDAY. WITH SIGNALS OF A LOW TO MID
LEVEL TROWAL SIGNATURE WRAPPING BACK AROUND THE LOW-MID LEVEL
LOW/S AND LLVL INVERTED SFC TROF WITH PLENTY OF LLVL CONVERGENT
STAYING POWER LATE TONIGHT AND ESPECIALLY ON TUE...HAVE ADJUSTED
HIGHER SNOWFALL AMOUNTS MORE FROM NORTHWEST TO SOUTHEAST ACRS THE
NORTHEASTERN HALF OF THE DVN CWA. 7.5 TO 9.5 INCHES AND ISOLATED
10+ INCH AMOUNTS NOW LOOK POSSIBLE BY 00Z WED GENERALLY ALONG AND
EAST OF A LINE FROM INDEPENDENCE IA...TO THE QUAD CITIES...AND
CAMBRIDGE/HENRY CO IL. WIDESPREAD 5.5 UP TO 8 INCHES ALONG AND
NORTH OF I80 WEST OF THE QUAD CITIES TO THIS LINE. PIVOTING DEF
ZONE MAY FOCUS EVEN HIGHER AMOUNTS FROM EAST OF CEDAR
RAPIDS...THOUGH STERLING IL AND PRINCETON IL TUE AFTERNOON. 3 TO
6 INCH AMOUNTS SOUTH OF I80 TO THE HWY 34 CORRIDOR....AND 3-4
INCHES SOUTH OF HWY 34 ACRS THE REST OF THE SOUTHERN CWA. THESE
AMOUNTS DERIVED USING THE EXTENT OF MOISTURE INFLUX...LSR/S OF
13:1 TO 15:1 AND ACCEPTED FORCING AND LONG DURATION. THESE AMOUNTS
ARE JUST THOUGH 00Z. SOME ADDITIONAL ACCUMS PAST 00Z WED IN THE
EAST...SEE DISCUSSION BELOW.
SO ALL IN ALL...HAVE EXPANDED THE WARNING TO THE CENTRAL I80
CORRIDOR AND THEN EAST OF THE QUAD CITIES THROUGH PUTNAM CO IL.
HAVE SPLIT UP START TIMES WITH THE EAST HALF NOT UNTIL AFTER 06Z
TONIGHT THROUGH 06Z WED. ADVISORIES EXPANDED SOUTHWARD TO INCLUDE
THE ENTIRE CWA AS WELL. SPLIT THE ADVISORY FROM WEST TO EAST WITH
START TIMES OF 00Z WEST OF THE MS RVR...AND 06Z TO THE EAST. BUT
EVEN IN THE WESTERN ADVISORY AREA ACCUMULATING SNOW NOT LIKELY TO START
TIL AFTER 03Z-04Z TUE OR SO. SFC WINDS INCREASING TO 15 TO 25 MPH WITH
GUSTS UP T0 35 MPH WRAPPING AROUND DEPARTING SFC TROF AS TUE
PROGRESSES. THUS THE AFTERNOON AND EVENING THE PRIME TIME FOR
DRIFTING AND SOME BLOWING SNOW TO COMPOUND TRAVEL CONDITIONS.
ANOTHER REASON OF EXPANDING THE ADVISORIES SOUTHWARD ALONG WITH
SOME SNOWFALL ADJUSTMENT UPWARD IN THOSE SOUTHERN AREAS. ..12..
LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
HEADLINES...HAVE EXTENDED THE WARNINGS/ADVISORIES IN OUR EASTERN CWA
TO MIDNIGHT TUESDAY NIGHT TO COVER THE TAIL END OF THE WINTER STORM.
TUESDAY NIGHT...HIGH CONFIDENCE. ADDITIONAL ACCUMULATIONS IN OUR
EASTERN HALF CWA IN THE EVENING WILL BE AROUND AN INCH OR LESS.
HOWEVER...NORTH WINDS WILL BE GUSTING TO 25 TO 30 MPH. TEMPERATURES
DURING THE EVENING WILL BE IN THE 20S SO BLOWING AND DRIFTING WILL
ADD TO TRAVEL DIFFICULTIES. THIS IS THE REASON FOR EXTENDING THE
WARNING TO MIDNIGHT. AFTER MIDNIGHT THE SNOW SHOULD HAVE ENDED IN
OUR FAR EAST AND WINDS AND CLOUDS DECREASE OVERNIGHT AS THE SYSTEM
PUSHES WELL OFF TO OUR EAST. MINIMUM TEMPERATURES WILL BE IN THE
TEENS NORTH TO AROUND 20 SOUTH.
WEDNESDAY THROUGH FRIDAY...MEDIUM TO HIGH CONFIDENCE. THIS IS A DRY
PERIOD. WE START OUT COLD WEDNESDAY AND WEDNESDAY NIGHT WITH HIGH
PRESSURE OVER THE CWA. BUT THEN ZONAL FLOW AND MILDER TEMPERATURES
RETURN LATE IN THE WEEK. WITH HIGH PRESSURE PROVIDING MOSTLY CLEAR
SKIES AND LIGHT WINDS ON WEDNESDAY NIGHT I HAVE LOWERED TEMPERATURES
FROM PREVIOUS SHIFT. THIS IS ESPECIALLY TRUE WITH A FRESH SNOW PACK.
WILL FORECAST SINGLE DIGITS NORTH AND TEENS SOUTH BUT THIS MAY STILL
NOT BE COLD ENOUGH. IF WE ARE TOTALLY CLEAR AND WINDS ARE CALM SOME
LOCATIONS MAY DIP BELOW ZERO IN OUR FAR NORTH.
FRIDAY NIGHT THROUGH MONDAY...LOW CONFIDENCE. STRONG STORM SYSTEM
WILL BE TRACKING OUT OF THE SOUTHERN ROCKIES/SOUTHERN PLAINS AND
THEN INTO THE MIDWEST. HOWEVER...AS USUAL A WEEK AWAY THE MODELS ARE
HAVING DIFFICULTY WITH STRENGTH AND TIMING OF THE SYSTEM. THE GFS
SUGGESTS A WET WEEKEND BUT THE ECMWF HAS SLOWED THE SYSTEM FROM
PREVIOUS RUNS AND KEEP THINGS DRY UNTIL MONDAY. BASED ON CONSENSUS
MODEL DATA THE GRIDS WILL HAVE CHANCE POPS FOR SATURDAY THROUGH
MONDAY. HOWEVER LATER SHIFTS MAY EITHER NEED TO ADJUST OR ELIMINATE
POPS ONCE CONFIDENCE IN THE MODEL DATA INCREASES.
HAASE
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WARNING UNTIL MIDNIGHT CST TUESDAY NIGHT FOR
CLINTON-DUBUQUE-JACKSON-MUSCATINE-SCOTT.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TUESDAY NIGHT FOR DES
MOINES-LOUISA.
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR BENTON-BUCHANAN-
CEDAR-DELAWARE-JOHNSON-JONES-LINN.
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR HENRY IA-IOWA-
JEFFERSON-KEOKUK-LEE-VAN BUREN-WASHINGTON.
IL...WINTER STORM WARNING UNTIL MIDNIGHT CST TUESDAY NIGHT FOR BUREAU-
CARROLL-HENRY IL-JO DAVIESS-PUTNAM-ROCK ISLAND-STEPHENSON-
WHITESIDE.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TUESDAY NIGHT FOR
HANCOCK-HENDERSON-MCDONOUGH-MERCER-WARREN.
MO...WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR CLARK-
SCOTLAND.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
552 PM CST MON MAR 4 2013
...UPDATED FOR AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 254 PM CST MON MAR 4 2013
WATER VAPOR AND HOURLY RAP ANALYSES SHOW A FAIRLY COMPACT JET STREAK
MOVING SOUTHEAST FROM IDAHO INTO COLORADO. THIS JET STREAK WAS WELL
TO THE SOUTHWEST OF THE MAIN UPPER LOW CENTER WHICH WAS CENTERED
ALONG THE WESTERN SOUTH DAKOTA-NORTH DAKOTA BORDER. THE FIRST
FRONTAL PASSAGE OCCURRED EARLIER IN THE DAY, BUT THE AIRMASS BEHIND
THIS FRONT WAS MAINLY DOWNSLOPE MODIFIED CONTINENTAL POLAR AIR...AND
NOT ARCTIC IN NATURE AT ALL. BECAUSE OF THIS...INSOLATION AND
CONTINUED DOWNSLOPE MODIFICATION YIELDED AFTERNOON TEMPERATURES
QUITE MILD AND RIGHT AROUND THE SEASONAL AVERAGE FOR EARLY MARCH.
THE EXCEPTION OF THIS WAS ACROSS SOUTH CENTRAL KANSAS WHERE
LINGERING SNOWPACK CONTINUED GENERALLY FROM HAYS TO KINSLEY TO
COLDWATER AND POINTS EAST (ESPECIALLY PRATT AND BARBER COUNTIES).
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 254 PM CST MON MAR 4 2013
LOWER-MID LEVEL CLOUD WILL CONTINUE TO INCREASE LATE THIS AFTERNOON
AND EVENING AS UPWARD VERTICAL MOTION INCREASES AHEAD OF THE
APPROACHING JET STREAK. RADAR ECHOES CONTINUED TO INCREASE ACROSS
NORTHEASTERN COLORADO AND AS THE UPPER JET STREAK APPROACHES WESTERN
KANSAS...FRONTOGENESIS IN THE MID TROPOSPHERE WILL FURTHER
INCREASE...AND RAIN/SNOW SHOWERS WILL INCREASE IN COVERAGE. POPS
WERE INCREASED TO THE 30-40 PERCENT ACROSS FAR WEST CENTRAL
KANSAS...AND THE CHALLENGE OF PRECIPITATION TYPE IS PRETTY HIGH
GIVEN THE RAPID COOLING OF THE 900-800MB LAYER EARLY THIS EVENING AS
THE SECOND COLD FRONT MOVES THROUGH AND EVAPORATIVE COOLING ENSUES.
THE INCREASING RADAR TRENDS ACROSS NORTHWEST KANSAS WOULD SUGGEST AN
INCREASE IN POPS ACROSS THE BOARD...SO BY PRESS TIME BEFORE 21Z WILL
HAVE POPS INCREASED AND SLIGHTLY HIGHER QPF AMOUNTS. THE PERIOD FROM
ROUGHLY 00Z TO 06Z WILL BE THE BEST TIME FRAME FOR LIGHT
ACCUMULATING PRECIPITATION AS THE 700MB FRONTOGENETIC MOVES QUICKLY
SOUTHEAST ACROSS WESTERN KANSAS. WILL BEGIN A RAPID CLEARING TREND
IN THE GRIDS TOWARD DAYBREAK TUESDAY. WE WILL REMAIN IN A FAIRLY
STRONG 850-700MB GRADIENT THROUGH MOST OF THE DAY TUESDAY WHICH WILL
KEEP WINDS UP IN THE BREEZY TO WINDY CATEGORY...BUT REMAINING BELOW
WIND ADVISORY CRITERIA AS IT LOOKS RIGHT NOW. HIGH TEMPERATURE
FORECAST WILL NOT BE CHANGED FROM THE GOING FORECAST WITH WIDESPREAD
LOWER TO MID 40S EXPECTED.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 324 PM CST MON MAR 4 2013
GOOD POTENTIAL EXISTS FOR COLDER TEMPERATURES OVERNIGHT TUESDAY
INTO EARLY WEDNESDAY MORNING. THE CENTER OF THE HIGH PRESSURE
SURFACE RIDGE AXIS WILL LIKELY BE CENTERED ACROSS CENTRAL KANSAS FOR
SEVERAL HOURS TUESDAY NIGHT. THIS WILL ALSO BE UNDER A VERY DRY DEEP
ATMOSPHERIC COLUMN, PROMOTING LONGWAVE RADIATIONAL COOLING.
SURFACE WINDS WILL QUICKLY TURN SOUTHEASTERLY ON THE WEST SIDE OF
THE RIDGE EARLY WEDNESDAY MORNING, AND EVEN BEFORE THAT ACROSS FAR
WESTERN KANSAS. THE MESOSCALE NAM INDICATES A POCKET OF THE COLDEST
POSSIBLE TEMPERATURES OF ALL MODEL OUTPUT AND MOS GUIDANCE. HOWEVER
IT APPEARS TO BE HAVING PROBLEMS ACCOUNTING FOR LEFTOVER SURFACE
SNOWDEPTH. THE ECMWF MOS APPEARS A GENERALLY REASONABLE BETTER
COMPROMISE IN THIS INSTANCE, AND WAS CLOSELY FOLLOWED WEDNESDAY
MORNING.
WEDNESDAY AFTERNOON WILL BRING WARMER TEMPERATURES, ESPECIALLY ACROSS
WESTERN KANSAS. THE NAM MODEL INDICATES A SHARP 850 MB LEVEL
TEMPERATURE GRADIENT ACROSS FROM AROUND DODGE CITY TO THE COLORADO
LINE, WITH SOUTHERLY SURFACE WINDS AROUND A DEVELOPING LEE SURFACE
LOW. EVEN WARMER BOUNDARY LAYER AIR WILL BE PRESENT EARLY BY
THURSDAY AFTERNOON. BY THURSDAY THE AXIS OF THE MID LEVEL THERMAL
RIDGE BECOMES CENTERED OVER THE HIGH PLAINS, AND THE SURFACE TROUGH
PULLS SLIGHTLY FARTHER EASTWARD, DRAWING IN WARMER AIR FROM THE
HIGHER TERRAIN OF SE COLORADO AND NE NEW MEXICO. WARMER OVERNIGHT
LOWS WILL BE EXPERIENCED AS WELL AS PERSISTENT SOUTHERLY WINDS
DURING THE OVERNIGHTS IN SLIGHTLY HIGHER THETA-E AIR. MELTING SNOW
IS LIKELY TO RE-FREEZE IN MOST CASES, AND IT IS NOT OBVIOUS AT THIS
POINT OF ANY NIGHTS APPEARING OVERLY PRONE TO DENSE FOG DEVELOPMENT.
A BETTER CHANCE FOR DENSE FOG WILL COME CLOSER TO THE BEGINNING OF
THE DYNAMIC LOW EXPECTED THIS WEEKEND STARTING AROUND FRIDAY.
LARGE UNCERTAINTY EXISTS WITH RESPECT TO THE STORM SYSTEM EXPECTED TO
INTENSIFY ACROSS THE CENTRAL HIGH PLAINS REGION BETWEEN FRIDAY AND
SUNDAY. THE ECMWF AND CANADIAN (GEM) MODELS ARE IN GENERALLY CLOSER
AGREEMENT TO ONE ANOTHER WITH A MORE BAROCLINIC SYSTEM, AS WELL AS
CONSIDERABLY SLOWER THAN THE GFS MODEL (BY AROUND 12 HOURS). THE
RECENT MODEL CONSENSUS, BLENDED WITH THE LAST FORECAST DOES LOWER
PROBABILITIES ON FRIDAY AND FRIDAY NIGHT, AND FOCUSES THE HIGHER
(LIKELY) CHANCES SATURDAY INTO SUNDAY. TEMPERATURES WILL ALSO BE A
CHALLENGE DURING THIS PERIOD. THE TRACK AND NATURE OF THE DYNAMIC
LOW WILL MAKE A LARGE DIFFERENCE, WITH A HIGH TEMPERATURE ENSEMBLE
SPREAD SATURDAY FROM THE LOW 40S TO LOW 60S. BETTER MODEL AGREEMENT
WILL BE LOOKED FOR AS THE SYSTEM BECOMES BETTER SAMPLED LATER IN THE
WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 547 PM CST MON MAR 4 2013
A SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT WERE PASSING ACROSS
SOUTHWEST KANSAS LATE THIS AFTERNOON. STRONG NORTH WINDS AT 20-25
KTS WILL GRADUALLY SETTLE DOWN TO AROUND 17-20 KTS BY 03-05Z AND THEN
TO ABOUT 15 KTS BY 12Z. A FEW RAIN OR SNOW SHOWERS MAY AFFECT THE
TAF SITES THROUGH 04Z BUT VISBYS AND CIGS SHOULD BE VFR AND
PERHAPS MVFR AT THE VERY WORST IN ONE OF THE SHOWERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 22 42 17 52 / 40 0 0 0
GCK 20 44 16 54 / 40 0 0 0
EHA 22 48 24 61 / 50 10 0 0
LBL 20 47 19 54 / 40 10 0 0
HYS 22 40 14 46 / 30 10 0 0
P28 25 43 16 49 / 20 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...RUSSELL
AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
624 PM EST MON MAR 4 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM EST MON MAR 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER THE
WRN DAKOTAS AND A DOWNSTREAM RIDGE OVER THE WRN GREAT LAKES. AT THE
SFC...A RIDGE EXTENDED FROM NRN MANITOBA AND NW ONTARIO INTO UPPER
MI BRINGING EASTERLY WINDS AND MAINLY CLEAR SKIES. CLOUDS ASSOCIATED
WITH THE BROAD AREA OF ISENTROPIC LIFT AHEAD OF THE SFC LOW VOER S
CNTRL N DAKOTA HAD SPREAD INTO FAR WRN UPPER MI WITH MAINLY ONLY
HIGH CLOUDS TO THE EAST.
MODELS WERE CONSISTENT IN TAKING THE DAKOTAS MID LEVEL LOW TO THE SE
TOWARD THE OH VALLEY BY TUE EVENING WITH BEST Q-VECT CONV AND
WAA/ISENTROPIC LIFT STAYING SE OF UPPER MI CLOSER TO THE TRACK OF
THE LOW AND ASSOC INVERTED SFC TROUGH. SO...MUCH OF THE CWA SHOULD
SEE LITTLE OR NO SYNOPTIC SCALE PCPN. CHANCE POPS STILL WERE
RETAINED OVER THE WEST WITH LITTLE IF ANY SNOW ACCUMULATION EXPECTED.
HOWEVER...HIGHER RES MODELS SUGGEST THAT AS NE FLOW STRENGTHENS AND
BECOMES MORE CYCLONIC PULLING 925-800 MB MOISTURE NE OF LAKE
SUPERIOR BACK INTO THE AREA...THE POTENTIAL FOR LAKE ENHANCED SNOW
INTO N CNTRL UPPER MI WILL INCREASE. WITH TEMPS NEAR THE 900 MB
INVERSION HEIGHT (NEAR 3K FT) ONLY AROUND -12C...BOTH INSTABILITY
AND SLR VALUES WILL BE MARGINAL FOR SIGNFICANT SNOW.
HOWEVER...UPSLOPE FLOW INTO THE HIGHER TERRAIN SHOULD BE ENOUGH TO
SUPPORT -SHSN BY TUE AFTERNOON WITH ACCUMULATIONS LESS THAN A HALF
INCH.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 356 PM EST MON MAR 4 2013
THE GENERALLY QUIET MARCH WEATHER CONTINUES THROUGH MUCH OF THE
LONG TERM PERIOD.
EXPECT SOME SNOW SHOWERS TO BE AFFECTING THE AREA
TUESDAY NIGHT INTO WEDNESDAY AS A LINGERING SURFACE TROUGH IS LEFT
BEHIND THE CLIPPER SYSTEM SLIDING TO THE SOUTH OF THE AREA TODAY
THROUGH TUESDAY. ALTHOUGH THE SYSTEM WILL BE TO THE SOUTH OF THE
AREA...DEEPER MOISTURE ROTATING WEST FROM THE LOW NEAR THE NEW
ENGLAND STATES WILL PROVIDE ENOUGH MOISTURE FOR SNOW TO DEVELOP
TUESDAY AFTERNOON INTO TUESDAY NIGHT. H850 TEMPERATURES OF -11C OVER
THE WEST AND -8C OVER THE EAST SHOULD BE COLD ENOUGH FOR LAKE
ENHANCEMENT...ESPECIALLY WITH THE ABUNDANT MOISTURE. IN
ADDITION...WITH THE LINGERING SURFACE TROUGH SLOWLY SLIDING ACROSS
THE AREA AND THE LEFTOVER NORTHERN STREAM SHORTWAVE AND ASSOCIATED
HEIGHT FALLS MOVING EAST ACROSS THE NORTHERN HALF OF THE
CWA...EXPECT A PERIOD OF LIGHT SNOW SHOWERS FOR THE WEST/CENTRAL
UPPER MICHIGAN TUESDAY NIGHT INTO WEDNESDAY. CYCLONIC
NORTH-NORTHEAST SFC-925 WINDS WOULD FAVOR THE NORTHWEST HALF OF
UPPER MICHIGAN FOR THE POPS. DID BUMP POPS UP SOME OVER THE
KEWEENAW FOR LATE TUESDAY NIGHT INTO WEDNESDAY MORNING...AS THERE
IS ADDITIONAL FORCING ALOFT FROM THE SHORTWAVE. SNOW RATIOS LOOK TO
BE ON THE LOW SIDE FOR MOST OF THE AREA...AT OR BELOW 10-1...SINCE
THE CLOUDS STRUGGLE TO GET ABOVE -10C. THERE IS A POTENTIAL FOR
SLIGHTLY HIGHER RATIOS OVER THE KEWEENAW DUE TO THE SYNOPTIC
FORCING...TOWARDS 15-1...BUT BEST FORCING LOOKS TO BE ABOVE THE DGZ
IN THAT AREA TO KEEP RATIOS FROM GETTING TOO HIGH. THE TROUGH
SLIDING EAST ON WEDNESDAY WILL TRANSITION THE LINGERING CLOUDS/SNOW
TO THE NORTHWEST WIND FAVORED LOCATIONS. MOST LOCATIONS WILL SEE A
LIGHT DUSTING OF SNOW BY WEDNESDAY EVENING...BUT SLIGHTLY HIGHER
AMOUNTS OF 1-2 INCHES ARE POSSIBLE OVER THE KEWEENAW AND THE HIGHER
TERRAIN OF MARQUETTE COUNTY.
THIS LINGERING TROUGH AND SHORTWAVE WILL SLIDE TO THE EAST OF THE
AREA ON WEDNESDAY...AS HIGH PRESSURE SLIDES EAST AND OVER THE UPPER
GREAT LAKES FOR WEDNESDAY NIGHT INTO THURSDAY BEFORE PUSHING EAST
ON FRIDAY. THIS HIGH SHOULD LEAD TO GRADUALLY DECREASING CLOUDS
DURING THAT PERIOD. ONCE AGAIN...THE POTENTIAL IS THERE FOR SOME
LINGERING FLURRIES OR STRATOCU STUCK BELOW THE INVERSION AROUND
2.5KFT. WILL PROBABLY BE SOMETHING SIMILAR TO THIS MORNINGS CLOUDS
FOR LOCATIONS FAVORED BY NORTH-NORTHWEST FLOW WEDNESDAY NIGHT INTO
THURSDAY. BUT WITH WINDS WEAKENING UNDER THE HIGH AND INCREASING DRY
AIR MOVING IN...WOULD THINK THAT THE LOW CLOUDS WOULD BE NEARLY GONE
ON THURSDAY NIGHT. WEDNESDAY NIGHT LOWS ARE TRICKY...SINCE THEY WILL
DEPEND ON WHERE THE CLOUDS ARE LOCATED. WHERE SKIES ARE
CLEAR...LIGHT WINDS AND PWAT VALUES TOWARDS 50 PERCENT OF NORMAL
WOULD LEAD TO GOOD RADIATIONAL COOLING. UPPER RIDGE WILL ALSO BUILD
OVER THE AREA DURING THIS TIME AND PRODUCE GRADUALLY WARMING
TEMPERATURES ALOFT...ESPECIALLY HEADING INTO THE WEEKEND AS
SOUTHERLY FLOW INCREASES WITH THE HIGH SLIDING TO THE EAST OF THE
AREA. THIS SHOULD TRANSITION THE AREA AWAY FROM THE BELOW NORMAL
TEMPERATURES THAT WE HAVE BEEN IN AND MORE NORMAL OR SLIGHT ABOVE
NORMAL HIGHS.
AS FOR PRECIPITATION HEADING INTO THE WEEKEND...THE CHANCES ALL
DEPEND ON THE STRENGTH OF THE UPPER RIDGE. THE FIRST SHORTWAVE WILL
RIDE UP THE UPPER RIDGE ON FRIDAY AND HEAD NORTHEAST TOWARDS JAMES
BAY ON FRIDAY NIGHT. 06Z GFS AND 00Z GEM HAVE IT FARTHER TO THE
SOUTHEAST AND MOVING ACROSS LAKE SUPERIOR...WHILE THE 00Z ECMWF
KEEPS IT WELL TO THE NORTHWEST IN ONTARIO. WITH THE SURFACE LOW
WELL TO THE NORTH OF THE AREA...SHOULD SEE A SURFACE TROUGH
PUSHING THROUGH THE AREA ON LATE FRIDAY NIGHT INTO SATURDAY. MODELS
VARYING ON TIMING AND AMOUNT OF MOISTURE ASSOCIATED WITH THE
SHORTWAVE AND THEN THE SURFACE TROUGH. THEY DO AGREE THAT DEEP
MOISTURE FOR WIDESPREAD SNOW SEEMS MARGINAL AND MORE LIKELY SEE
ISOLATED TO SCATTERED SNOW SHOWERS DURING THAT PERIOD.
UNCERTAINTY GROWS AFTER SATURDAY...AS THERE ARE LARGE MODEL AND
RUN-TO-RUN DIFFERENCES IN THE HANDLING OF THE UPPER LOW OVER THE
SOUTHWESTERN CONUS AND HOW THE NORTHERN AND SOUTHERN JET STREAMS
PHASE AS THE TROUGH SLIDES EAST. MODELS HAVE A DIFFICULT TIME WITH
PHASING SYSTEMS A DAY OR TWO OUT...SO DON/T HAVE ANY CONFIDENCE TO
GO MORE THAN A CONSENSUS CHANCE POPS FOR MONDAY WITH THE LOW MOVING
THROUGH THE GREAT LAKES. DESPITE THESE DIFFERENCES...BOTH THE LONGER
RANGE GFS/ECMWF DO SHOW THE UPPER TROUGH REESTABLISHING OVER THE
CENTRAL CONUS BY THE MIDDLE OF NEXT WEEK. THIS PRODUCES A POTENTIAL
FOR ANOTHER BELOW NORMAL TEMPERATURE PERIOD FOR THE UPPER GREAT
LAKES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 623 PM EST MON MAR 4 2013
EXPECT SNOW SHOWERS TO BEGIN LATE TONIGHT AT ALL THREE TAF SITES.
LOW PRESSURE WILL MOVE FROM THE NORTHERN PLAINS INTO THE OHIO VALLEY
OVERNIGHT AND TUESDAY. THIS WILL BRING SOME HIGH-MID LEVEL CLOUDS TO
THE AREA OVERNIGHT...AND LIMITED SUPPORT FOR SNOW AT IWD TONIGHT.
OTHERWISE...THIS SYSTEM WILL ALLOW SURFACE WINDS TO REMAIN EAST TO
NORTHEASTERLY INTO TOMORROW. AS A RESULT...LAKE EFFECT SNOW SHOWERS
WILL DEVELOP LATE TONIGHT AND LAST THROUGH TUESDAY AT ALL THREE
SITES. OVERALL...CONDITIONS SHOULD BE VFR THROUGH THE EARLY EVENING
TONIGHT...THEN DETERIORATE TO LOW END MVFR TOWARDS MORNING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EST MON MAR 4 2013
AS LOW PRESSURE OVE THE DAKOTAS SLIDES TO THE SE...NE WINDS TO 30
KTS ARE EXPECTED MON NIGHT THROUGH TUE...ESPECIALLY OVER THE WRN
THIRD OF THE LAKE WHERE LOW LEVEL CONV IS STRONGEST. NORTH WINDS TO 25 KTS
CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY WINDS AND COLDER
TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT TIMES THROUGH
WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS LATER
WEDNESDAY INTO FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...MCD
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
351 PM EST SUN MAR 3 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 350 PM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A VIGOROUS SHORTWAVE TROUGH
OVER NRN MONTANA...A MID/UPPER LEVEL RIDGE OVER THE PLAINS AND NE
CANADA AND TROUGHING OVER NRN MANTIOBA AND THE SE CONUS LEAVING A
COL OVER THE NRN GREAT LAKES. AT THE SFC...A RIDGE EXTENDED FROM NW
ONTARIO THROUGH WRN UPPER MI INTO WI AND IL. SIMILAR TO
YESTERDAY...LES AND CLOUDS HAVE DIMINISHED DURING THE AFTERNOON AS
DAYTIME MIXING AND VERY DRY AIS UPSTREAM HELPS ERODE THE
CLOUD BANDS.
TONIGHT AND MON...ALSO SIMILAR TO PREVIOUS FEW NIGHTS...EXPECT SOME LES
TO REDEVLOP OVERNIGHT AS UPSTREAM MIXING/DRYING SUBSIDES AND LAND
BREEZES DEVELOP. HOWEVER...HIGH RES MODELS SUGGEST THAT LOW LEVEL
CONV WILL BE WEAKER THAN LAST NIGHT WITH MAINLY DIFLUENT ACYC FLOW
OVER THE THE WEST HALF OF LAKE SUPERIOR. WEAK UPSLOPE FLOW INTO N
CNTRL UPPER MI SHOULD HELP PRODUCE AT LEAST SOME FLURRIES EVEN WITH
INVERSION HEIGHTS AT OR BELOW 2K-3K FT. WITH LOW CONFIDENCE IN EVEN
ANY LIGHT MEASURABLE LES...FCST RETAINED PREV MENTION OF SLIGHT
CHANCE POPS. FAVORABLE RADIATIONAL COOLING CONDITIONS INLAND SHOULD
WILL ALLOW TEMPS TO DROP TO LOWER END OF GUIDANCE WITH READINGS IN
THE 0 TO 10 BELOW ZERO RANGE.
AS ACYC WINDS BACK TO THE ENE...EXPECT REMAINING LES/FLURRIES TO END
BY MIDDAY MON. TEMPS SHOULD REBOUND TO READINGS CLOSER TO SEASONAL
AVERAGES NEAR 30...PER FCST SOUNDINGS LOW LEVEL TEMP PROFILE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 PM EST SUN MAR 3 2013
FOCUS INITIALY IS ON SHORTWAVE TROUGH DIGGING SOUTHEAST ACROSS
NORTHERN PLAINS. CONVERGENCE AND MOISTURE ADVECTION ALONG AND
NORTH OF SFC/H85/H7 LOWS AND DIVERGENCE ALOFT FROM H25 JET STREAK
SHOULD BE SUPPORTING SWATH OF MODERATE TO HEAVY SNOW FROM EASTERN
NORTH DAKOTA THROUGH MOST OF MINNESOTA AND INTO SOUTHERN WISCONSIN.
H85-H7 FRONTOGENESIS AND H85 MOISTURE STAY FAR ENOUGH TO SOUTH TO
KEEP NORTHERN EDGE OF SNOW SHIELD OUT OF CWA MONDAY NIGHT. H7-H6
FRONTOGENESIS AND INCREASING 1000-700MB MOISTURE PROBABLY WILL ALLOW
SYSTEM SNOW TO CLIP FAR WEST TUESDAY. KIWD WOULD SEE BEST CHANCE OF
SEEING THIS SYSTEM SNOW. FARTHER NORTH...EXPECT INCREASING LIGHT
SNOW MAINLY DUE TO WINDS BECOMING MORE NORTHEAST AND WITH INCREASING
925-850MB MOISTURE. THE ADDITIONAL MOISTURE ALONG WITH FLOW OFF LK
SUPERIOR AND MINOR COOLING AT TOP OF INVERSION TO AROUND -12C WILL
BE SUFFICIENT TO RESULT IN LAKE ENHANCED SNOW. GIVEN THE PERSISTENT
LIGHT LK EFFECT SEEN OFF AND ON OVER NCNTRL UPR MICHIGAN SINCE
THURSDAY WITH QUITE MARGINAL CONDITIONS IN TERMS OF INVERSION
HEIGHT/TEMPS...PRETTY CONFIDENT SNOW WILL OCCUR TUESDAY/TUESDAY
NIGHT/WEDNESDAY MORNING. TOTAL SNOW ACCUMULATIONS WILL BE LIMITED
GIVEN ABSENCE OF LARGER SCALE FORCING AND WITH MAJORITY OF LIFT
OCCURRING AT TEMPS WARMER THAN -10C LEADING TO SLR/S LESS THAN 10:1.
EVEN SO...SOME HIGHER TERRAIN AREAS OVER FAR WESTERN UPR MICHIGAN
AND IN NCNTRL UPR MICHIGAN MAY END UP WITH A FEW INCHES OF SNOW BY
LATER WEDNESDAY.
H925 TEMPS AROUND -10C WITH WEAK NORTHERLY WINDS AND SUFFICIENT
MOISTURE BLO INVERSION WILL RESULT IN LIGHT LK EFFECT PERSISTING
THROUGH LATE WEDNESDAY. SINCE SFC-H925MB WINDS DO NOT BECOME MORE
SOUTHERLY UNTIL THURSDAY MORNING...LIGHT LK EFFECT/FLURRIES PROBABLY
WILL LINGER ALONG PORTIONS OF LK SUPERIOR SHORE WEDNESDAY NIGHT. BY
TIME WINDS DO BECOME MORE SOUTHERLY...TEMPS ARE FURTHER WARMING...SO
DO NOT EXPECT ANY LK EFFECT OFF LK MICHIGAN. COULD BE ENHANCEMENT TO
CLOUDS THOUGH WHICH WOULD TEMPER WARMING ON THURSDAY FOR THE EAST.
H5 RIDGE BUILDS FROM CNTRL CONUS ACROSS GREAT LAKES THURSDAY INTO
FRIDAY. BY LATER FRIDAY...TROUGH OVER WESTERN CONUS SPLITS LEAVING
SEPARATE SOUTHERN STREAM TROUGH OVER SOUTHWEST CONUS AND NORTHERN
STREAM TROUGH PUSHING ACROSS SCNTRL CANADA. SFC-H85 TROUGHING FORMS
IN RESPONSE OVER THE NORTEHRN PLAINS WHICH INCREASES SOUTHERLY
WINDS OVER UPR LAKES THURSDAY NIGHT INTO FRIDAY. WINDS MAY BECOME
BREEZY WITH GUSTS OVER 20 MPH...BUT LACK OF STRONGER PRESSURE
GRADIENT WILL KEEP REAL STRONG WINDS FROM OCCURRING.
GFS INDICATES STRONGER NORTHERN STREAM DYNAMICS HEAD EAST QUICKLY ON
FRIDAY WHILE OUTRUNNING THE SFC TROUGH...SO THE TROUGH REALLY LOSES
ITS PUNCH AS IT MOVES ACROSS THE AREA. ECMWF FAIRLY SIMILAR WITH
OVERALL IDEA. SHOULD NOTE THAT THE GEM-NH A BIT STRONGER/FARTHER
SOUTH WITH NORTHERN STREAM WAVE SO IT GENERATES MORE QPF IN WARM AIR
ADVECTION AHEAD OF THE WAVE ON FRIDAY. GFS TRYING TO GENERATE SOME
LGT DRIZZLE LIKE PRECIP ON FRIDAY WITH LOW-LEVEL MOISTURE BENEATH
DRIER AIR IN MID LEVELS. THINK THAT LACK OF DEEPER MOISTURE INTO THE
SYSTEM SUGGESTS THAT NOT MUCH PRECIPITATION WILL OCCUR ON FRIDAY.
WILL NOT ALTER SLIGHT CHANCE POPS FROM CONSENSUS OF MODELS. SOME
INDICATION THAT AS WARMING KICKS IN ABOVE H9 AHEAD OF THE
TROUGH...LOW-LEVEL MOISTURE MAY REMAIN TRAPPED BENEATH THE INVERSION
OVER MUCH OF CWA RIGHT THROUGH FRIDAY. MAIN IMPACT WILL BE ON TEMPS
THURSDAY THROUGH FRIDAY. DUE TO STRICT TEMPERATURE ADVECTION WOULD
THINK MANY AREAS THURSDAY AND FRIDAY WILL STILL BE ABLE TO CRACK THE
FREEZING MARK.
MODELS NOT AS COLD IN WAKE OF FRONT NEXT WEEKEND AS THEY HAVE SHOWED
LAST COUPLE DAYS. ULTIMATELY MAY END UP BEING DRY NEXT WEEKEND /JUST
HAVE SLIGHT CHANCES IN THERE/ WITH TEMPERATURES SIMILAR TO LATE THIS
WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1251 PM EST SUN MAR 3 2013
EXPECT INCREASED DAYTIME MIXING AND DRY ADVECTION TO AGAIN RESULT IN
CLEARING AT SAW...WITH VFR CONDITIONS BY MID TO LATE AFTERNOON.
OTHERWISE...VFR CONDITIONS WILL PREAVIL THROUGH THE FCST PERIOD WITH
A SURFACE RIDGE DOMINATING THE WEATHER IN THE NORTHERN GREAT LAKES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 350 PM EST SUN MAR 3 2013
STRONGEST WINDS THIS WEEK OCCUR MONDAY AFTERNOON THROUGH TUESDAY
OVER FAR WESTERN LAKE SUPERIOR AS LOW PRESSURE SYSTEM MOVES BY JUST
TO THE SOUTH. EAST-NORTHEAST WINDS TO 30 KTS GOOD BET. MAY BE GALE
GUSTS TOWARD THE HEAD OF LK SUPERIOR AND ALONG THE MINNESOTA SHORE
MONDAY NIGHT INTO TUESDAY MORNING DUE TO COASTAL CONVERGENCE. NORTH
WINDS TO 25 KTS CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY
WINDS AND COLDER TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT
TIMES THROUGH WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS
LATER WEDNESDAY AND THURSDAY AS HIGH PRESSURE CROSSES THE REGION.
SOUTH WINDS TO 25 KTS POSSIBLE THURSDAY NIGHT INTO FRIDAY OUT AHEAD
OF LOW PRESSURE TROUGH. TROUGH MOVES THROUGH FRIDAY NIGHT BUT
WEST-NORTHWEST WINDS IN WAKE OF TROUGH SHOULD STAY BLO 20 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1252 PM EST SUN MAR 3 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AND NW ONTARIO THROUGH WRN
LAKE SUPERIOR. IN PAST FEW HOURS...COMBINATION OF SUBTLE TROUGHING
AND LOW-LVL CONVERGENCE OVER ERN LAKE SUPERIOR ALONG WITH THE INFLUX
OF SLIGHTLY MORE MOIST AIR AT LOW-LVLS FROM NE OF LAKE SUPERIOR AND
WEAK Q-VECT CONV HAS LEAD TO THE FORMATION OF LAKE CLOUDS AND LIGHT
-SHSN/FLURRIES FROM MARQUETTE EASTWARD AS NOTED ON IR SATELLITE AND
MQT RADAR LOOPS. CLEAR SKIES AND LIGHT WINDS UNDER SFC RDG AXIS HAVE
ALLOWED TEMPS TO DROP WELL BLO ZERO AT MANY LOCATIONS EARLY THIS
MORNING. LOWEST READINGS THUS FAR HAVE BEEN -9F AT KIWD...-4F AT
KCMX AND -2F AT NWS MQT. LAND O LAKES JUST SOUTH OF WATERSMEET HAS
PLUMMETED TO -13F.
TODAY...SIMILAR TO YESTERDAY...EXPECT CLOUDS AND ASSOC LES TO
GENERALLY DISSIPATE BY LATE MORNING/EARLY AFTERNOON AS LOW-LVL
CONVERGENCE WEAKENS AND Q-VECT DIVERGENCE SPREADS IN FROM THE WEST
WITH ADVANCING MID-LVL RDG. EXPECT MAX TEMPERATURES AGAIN SIMILAR TO
YESTERDAY WITH HIGHS RANGING FROM THE LOWER 20S NORTH CENTRAL AND
EAST TO THE MID TO UPPER 20S ELSEWHERE.
NOT AS CONFIDENT ON DEVELOPMENT OF LAKE EFFECT CLOUDS TONIGHT AS
MODEL FCST SNDGS SHOW SUBSIDENCE INVERSION CRASHING TOWARD SFC WITH
STRONG AMPLIFIED RDG MOVING OVER THE AREA. THIS IS ALSO WELL
DEPICTED ON SNDGS WITH STRONG MID-LVL DRYING AND Q-VECT DIV. LOW-LVL
WINDS ARE ALSO GENERALLY MORE DIFLUENT...ALTHOUGH THERE IS STILL
SOME SUBTLE TROFFING AND WEAKLY CONVERGENT NNE FLOW FROM EASTERN
LAKE SUPERIOR INTO NCNTRL COUNTIES...ESPECIALLY ERN MQT AND WRN
ALGER. HAVE TRIMMED BACK POPS SOME FROM PREV FCST DUE TO
AFOREMENTIONED NEGATIVE FACTORS FOR LES...BUT WILL KEEP SOME SLIGHT
CHC POPS OVER ERN MQT/WRN ALGER IN CASE SOME LIGHT LES/FLURRIES CAN
BE INITIATED THERE DUE TO WEAK LOW-LVL CONVERGENCE. EXPECT SOME
SUB-ZERO LOW TEMPS AGAIN OVER THE FAR WRN INTERIOR UNDER CLEAR SKIES
AND LIGHT WINDS OF SFC RDG AXIS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 511 AM EST SUN MAR 3 2013
SOME LIGHT LINGERING LES WILL CONTINUE ON MON IN NE LOW LEVEL FLOW
AS SFC AND UPPER LEVEL RIDGING MOVES IN. GIVEN MARGINAL TEMPS FOR
LES AND OVERALL CONDITIONS THAT WILL BE DETRIMENTAL TO LES...ONLY
SLIGHT CHANCE POPS WILL BE MAINTAINED ON MON.
CONDITIONS BECOME MORE FAVORABLE FOR LES TUE INTO WED AS AN UPPER
TROUGH MOVES OVER THE REGION...BRINGING COLDER INVERSION TEMP TEMPS
AROUND -13C AT 900MB...BETTER MOISTURE AND CYCLONIC FLOW. LOW LEVEL
WINDS WILL CONTINUE TO BE OUT OF THE NE-N...SO THE MOST FAVORED
AREAS WILL BE OVER THE HIGHER TERRAIN OF N CENTRAL UPPER MI. COULD
SEE A FEW INCHES OF ACCUMULATION...BUT NOT EXPECTED TOO LARGE OF
AMOUNTS GIVEN MORE MARGINAL INVERSION TOP TEMPS.
THERE ARE TIMING DIFFERENCES BETWEEN MODELS...BUT THEY DO AGREE ON
THE GENERAL IDEA OF BRINGING A SFC HIGH FOLLOWED BY UPPER RIDGING ON
OR AROUND THU. A SERIES OF SHORTWAVE TROUGHS ARE FORECAST TO MOVE
NEARBY FRI AND SAT...BUT NOT SIGNIFICANT PRECIP IS EXPECTED AT THIS
TIME AND CONFIDENCE IS LOWER GIVEN LIMITATION OF NWP WITH THESE
FEATURES THAT FAR OUT.
TAKING A QUICK LOOK AT SFC TEMPS THROUGH THE LONG TERM /SINCE THERE
IS LITTLE ELSE TO TALK ABOUT/...HIGHS MON ARE FORECAST TO BY AROUND
30...AND SHOULD THEN DROP A FEW DEGREES FOR TUE BEFORE SIMILAR TEMPS
COME BACK ON WED. THU SHOULD SEE HIGHS AOA FREEZING IN MOST
LOCATIONS...WITH EVEN WARMER HIGHS IN THE MID TO UPPER 30S ON FRI
AND SAT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1251 PM EST SUN MAR 3 2013
EXPECT INCREASED DAYTIME MIXING AND DRY ADVECTION TO AGAIN RESULT IN
CLEARING AT SAW...WITH VFR CONDITIONS BY MID TO LATE AFTERNOON.
OTHERWISE...VFR CONDITIONS WILL PREAVIL THROUGH THE FCST PERIOD WITH
A SURFACE RIDGE DOMINATING THE WEATHER IN THE NORTHERN GREAT LAKES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EST SUN MAR 3 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WEST AND NORTH CENTRAL SECTIONS BY MONDAY
NIGHT AS LOW PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN
MISSISSIPPI RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK
SUPERIOR THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY
WEDNESDAY. WEAK PRES GRADIENT OVER AREA WILL MAINTAIN FAIRLY LIGHT
WINDS OF 20 KT OR LESS THROUGH THE REST OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
701 AM EST SUN MAR 3 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AND NW ONTARIO THROUGH WRN
LAKE SUPERIOR. IN PAST FEW HOURS...COMBINATION OF SUBTLE TROUGHING
AND LOW-LVL CONVERGENCE OVER ERN LAKE SUPERIOR ALONG WITH THE INFLUX
OF SLIGHTLY MORE MOIST AIR AT LOW-LVLS FROM NE OF LAKE SUPERIOR AND
WEAK Q-VECT CONV HAS LEAD TO THE FORMATION OF LAKE CLOUDS AND LIGHT
-SHSN/FLURRIES FROM MARQUETTE EASTWARD AS NOTED ON IR SATELLITE AND
MQT RADAR LOOPS. CLEAR SKIES AND LIGHT WINDS UNDER SFC RDG AXIS HAVE
ALLOWED TEMPS TO DROP WELL BLO ZERO AT MANY LOCATIONS EARLY THIS
MORNING. LOWEST READINGS THUS FAR HAVE BEEN -9F AT KIWD...-4F AT
KCMX AND -2F AT NWS MQT. LAND O LAKES JUST SOUTH OF WATERSMEET HAS
PLUMMETED TO -13F.
TODAY...SIMILAR TO YESTERDAY...EXPECT CLOUDS AND ASSOC LES TO
GENERALLY DISSIPATE BY LATE MORNING/EARLY AFTERNOON AS LOW-LVL
CONVERGENCE WEAKENS AND Q-VECT DIVERGENCE SPREADS IN FROM THE WEST
WITH ADVANCING MID-LVL RDG. EXPECT MAX TEMPERATURES AGAIN SIMILAR TO
YESTERDAY WITH HIGHS RANGING FROM THE LOWER 20S NORTH CENTRAL AND
EAST TO THE MID TO UPPER 20S ELSEWHERE.
NOT AS CONFIDENT ON DEVELOPMENT OF LAKE EFFECT CLOUDS TONIGHT AS
MODEL FCST SNDGS SHOW SUBSIDENCE INVERSION CRASHING TOWARD SFC WITH
STRONG AMPLIFIED RDG MOVING OVER THE AREA. THIS IS ALSO WELL
DEPICTED ON SNDGS WITH STRONG MID-LVL DRYING AND Q-VECT DIV. LOW-LVL
WINDS ARE ALSO GENERALLY MORE DIFLUENT...ALTHOUGH THERE IS STILL
SOME SUBTLE TROFFING AND WEAKLY CONVERGENT NNE FLOW FROM EASTERN
LAKE SUPERIOR INTO NCNTRL COUNTIES...ESPECIALLY ERN MQT AND WRN
ALGER. HAVE TRIMMED BACK POPS SOME FROM PREV FCST DUE TO
AFOREMENTIONED NEGATIVE FACTORS FOR LES...BUT WILL KEEP SOME SLIGHT
CHC POPS OVER ERN MQT/WRN ALGER IN CASE SOME LIGHT LES/FLURRIES CAN
BE INITIATED THERE DUE TO WEAK LOW-LVL CONVERGENCE. EXPECT SOME
SUB-ZERO LOW TEMPS AGAIN OVER THE FAR WRN INTERIOR UNDER CLEAR SKIES
AND LIGHT WINDS OF SFC RDG AXIS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 511 AM EST SUN MAR 3 2013
SOME LIGHT LINGERING LES WILL CONTINUE ON MON IN NE LOW LEVEL FLOW
AS SFC AND UPPER LEVEL RIDGING MOVES IN. GIVEN MARGINAL TEMPS FOR
LES AND OVERALL CONDITIONS THAT WILL BE DETRIMENTAL TO LES...ONLY
SLIGHT CHANCE POPS WILL BE MAINTAINED ON MON.
CONDITIONS BECOME MORE FAVORABLE FOR LES TUE INTO WED AS AN UPPER
TROUGH MOVES OVER THE REGION...BRINGING COLDER INVERSION TEMP TEMPS
AROUND -13C AT 900MB...BETTER MOISTURE AND CYCLONIC FLOW. LOW LEVEL
WINDS WILL CONTINUE TO BE OUT OF THE NE-N...SO THE MOST FAVORED
AREAS WILL BE OVER THE HIGHER TERRAIN OF N CENTRAL UPPER MI. COULD
SEE A FEW INCHES OF ACCUMULATION...BUT NOT EXPECTED TOO LARGE OF
AMOUNTS GIVEN MORE MARGINAL INVERSION TOP TEMPS.
THERE ARE TIMING DIFFERENCES BETWEEN MODELS...BUT THEY DO AGREE ON
THE GENERAL IDEA OF BRINGING A SFC HIGH FOLLOWED BY UPPER RIDGING ON
OR AROUND THU. A SERIES OF SHORTWAVE TROUGHS ARE FORECAST TO MOVE
NEARBY FRI AND SAT...BUT NOT SIGNIFICANT PRECIP IS EXPECTED AT THIS
TIME AND CONFIDENCE IS LOWER GIVEN LIMITATION OF NWP WITH THESE
FEATURES THAT FAR OUT.
TAKING A QUICK LOOK AT SFC TEMPS THROUGH THE LONG TERM /SINCE THERE
IS LITTLE ELSE TO TALK ABOUT/...HIGHS MON ARE FORECAST TO BY AROUND
30...AND SHOULD THEN DROP A FEW DEGREES FOR TUE BEFORE SIMILAR TEMPS
COME BACK ON WED. THU SHOULD SEE HIGHS AOA FREEZING IN MOST
LOCATIONS...WITH EVEN WARMER HIGHS IN THE MID TO UPPER 30S ON FRI
AND SAT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 653 AM EST SUN MAR 3 2013
EXPECT VFR CONDITIONS AT THE TAF SITES WITH THE EXCEPTION OF SOME
MVFR LAKE CLOUDS/FLURRIES AT KSAW THIS MORNING. MID-UPPER LEVEL RIDGE
BUILDING OVER THE REGION AND ASSOC DRYING WILL BE MORE PROHIBITIVE
FOR LAKE CLOUDS AND FLURRIES TO FORM TONIGHT DESPITE WEAK NNE FLOW...SO
HAVE DECIDED TO MAINTAIN VFR CONDITIONS THROUGH TONIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EST SUN MAR 3 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WEST AND NORTH CENTRAL SECTIONS BY MONDAY
NIGHT AS LOW PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN
MISSISSIPPI RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK
SUPERIOR THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY
WEDNESDAY. WEAK PRES GRADIENT OVER AREA WILL MAINTAIN FAIRLY LIGHT
WINDS OF 20 KT OR LESS THROUGH THE REST OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
513 AM EST SUN MAR 3 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AND NW ONTARIO THROUGH WRN
LAKE SUPERIOR. IN PAST FEW HOURS...COMBINATION OF SUBTLE TROUGHING
AND LOW-LVL CONVERGENCE OVER ERN LAKE SUPERIOR ALONG WITH THE INFLUX
OF SLIGHTLY MORE MOIST AIR AT LOW-LVLS FROM NE OF LAKE SUPERIOR AND
WEAK Q-VECT CONV HAS LEAD TO THE FORMATION OF LAKE CLOUDS AND LIGHT
-SHSN/FLURRIES FROM MARQUETTE EASTWARD AS NOTED ON IR SATELLITE AND
MQT RADAR LOOPS. CLEAR SKIES AND LIGHT WINDS UNDER SFC RDG AXIS HAVE
ALLOWED TEMPS TO DROP WELL BLO ZERO AT MANY LOCATIONS EARLY THIS
MORNING. LOWEST READINGS THUS FAR HAVE BEEN -9F AT KIWD...-4F AT
KCMX AND -2F AT NWS MQT. LAND O LAKES JUST SOUTH OF WATERSMEET HAS
PLUMMETED TO -13F.
TODAY...SIMILAR TO YESTERDAY...EXPECT CLOUDS AND ASSOC LES TO
GENERALLY DISSIPATE BY LATE MORNING/EARLY AFTERNOON AS LOW-LVL
CONVERGENCE WEAKENS AND Q-VECT DIVERGENCE SPREADS IN FROM THE WEST
WITH ADVANCING MID-LVL RDG. EXPECT MAX TEMPERATURES AGAIN SIMILAR TO
YESTERDAY WITH HIGHS RANGING FROM THE LOWER 20S NORTH CENTRAL AND
EAST TO THE MID TO UPPER 20S ELSEWHERE.
NOT AS CONFIDENT ON DEVELOPMENT OF LAKE EFFECT CLOUDS TONIGHT AS
MODEL FCST SNDGS SHOW SUBSIDENCE INVERSION CRASHING TOWARD SFC WITH
STRONG AMPLIFIED RDG MOVING OVER THE AREA. THIS IS ALSO WELL
DEPICTED ON SNDGS WITH STRONG MID-LVL DRYING AND Q-VECT DIV. LOW-LVL
WINDS ARE ALSO GENERALLY MORE DIFLUENT...ALTHOUGH THERE IS STILL
SOME SUBTLE TROFFING AND WEAKLY CONVERGENT NNE FLOW FROM EASTERN
LAKE SUPERIOR INTO NCNTRL COUNTIES...ESPECIALLY ERN MQT AND WRN
ALGER. HAVE TRIMMED BACK POPS SOME FROM PREV FCST DUE TO
AFOREMENTIONED NEGATIVE FACTORS FOR LES...BUT WILL KEEP SOME SLIGHT
CHC POPS OVER ERN MQT/WRN ALGER IN CASE SOME LIGHT LES/FLURRIES CAN
BE INITIATED THERE DUE TO WEAK LOW-LVL CONVERGENCE. EXPECT SOME
SUB-ZERO LOW TEMPS AGAIN OVER THE FAR WRN INTERIOR UNDER CLEAR SKIES
AND LIGHT WINDS OF SFC RDG AXIS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 511 AM EST SUN MAR 3 2013
SOME LIGHT LINGERING LES WILL CONTINUE ON MON IN NE LOW LEVEL FLOW
AS SFC AND UPPER LEVEL RIDGING MOVES IN. GIVEN MARGINAL TEMPS FOR
LES AND OVERALL CONDITIONS THAT WILL BE DETRIMENTAL TO LES...ONLY
SLIGHT CHANCE POPS WILL BE MAINTAINED ON MON.
CONDITIONS BECOME MORE FAVORABLE FOR LES TUE INTO WED AS AN UPPER
TROUGH MOVES OVER THE REGION...BRINGING COLDER INVERSION TEMP TEMPS
AROUND -13C AT 900MB...BETTER MOISTURE AND CYCLONIC FLOW. LOW LEVEL
WINDS WILL CONTINUE TO BE OUT OF THE NE-N...SO THE MOST FAVORED
AREAS WILL BE OVER THE HIGHER TERRAIN OF N CENTRAL UPPER MI. COULD
SEE A FEW INCHES OF ACCUMULATION...BUT NOT EXPECTED TOO LARGE OF
AMOUNTS GIVEN MORE MARGINAL INVERSION TOP TEMPS.
THERE ARE TIMING DIFFERENCES BETWEEN MODELS...BUT THEY DO AGREE ON
THE GENERAL IDEA OF BRINGING A SFC HIGH FOLLOWED BY UPPER RIDGING ON
OR AROUND THU. A SERIES OF SHORTWAVE TROUGHS ARE FORECAST TO MOVE
NEARBY FRI AND SAT...BUT NOT SIGNIFICANT PRECIP IS EXPECTED AT THIS
TIME AND CONFIDENCE IS LOWER GIVEN LIMITATION OF NWP WITH THESE
FEATURES THAT FAR OUT.
TAKING A QUICK LOOK AT SFC TEMPS THROUGH THE LONG TERM /SINCE THERE
IS LITTLE ELSE TO TALK ABOUT/...HIGHS MON ARE FORECAST TO BY AROUND
30...AND SHOULD THEN DROP A FEW DEGREES FOR TUE BEFORE SIMILAR TEMPS
COME BACK ON WED. THU SHOULD SEE HIGHS AOA FREEZING IN MOST
LOCATIONS...WITH EVEN WARMER HIGHS IN THE MID TO UPPER 30S ON FRI
AND SAT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1250 AM EST SUN MAR 3 2013
DIFFICULT FORECAST CONTINUES WITH OFF AND ON AGAIN LAKE EFFECT
CLOUDS WITH NORTHERLY UPSLOPE DIRECTION CONTINUING. EACH
DAY...DIURNAL HEATING HAS MIXED OUT THE MVFR DECK WITH SOME DRIER
AIR. PERSISTENCE WITH THIS THEME WILL CONTINUE AT SAW AND CMX. VFR
CONDITIONS OVERNIGHT WILL BE REPLACED WITH THE MVFR CLOUDS
LATE TONIGHT AND THIS WILL LAST INTO SUN AFTERNOON BEFORE HEATING
AND MIXING AGAIN MIXES THIS LOW DECK BACK OUT. VFR CONDITIONS WILL
CONTINUE AT IWD THROUGH THE PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EST SUN MAR 3 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WEST AND NORTH CENTRAL SECTIONS BY MONDAY
NIGHT AS LOW PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN
MISSISSIPPI RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK
SUPERIOR THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY
WEDNESDAY. WEAK PRES GRADIENT OVER AREA WILL MAINTAIN FAIRLY LIGHT
WINDS OF 20 KT OR LESS THROUGH THE REST OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...07
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1252 AM EST SUN MAR 3 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AN NW ONTARIO THROUGH WRN
LAKE SUPERIOR. DAYTIME MIXING AND LOW LEVEL DRYING UPSTREAM
(DEWPOINT DEPRESSIONS AOA 30F) HAS SUBSTANTIALLY REDUCED THE
COVERAGE/INTENSITY OF LES INTO N CNTRL UPPER MI THIS AFTERNOON.
TONIGHT...A WEAK SHORTWAVE TROUGH TO NEAR INL WILL DIVE SE
REINFORCING THE MID LEVEL TROUGH OVER THE NRN GREAT LAKES.
HOWEVER..THE SFC RIDGE EXTENDING SOUTH FROM THE HUDSON BAY HIGH WILL
CONTINUE TO BE THE DOMINANT FEATURE OVER THE AREA. INVERSION HEIGHTS
BETWEEN 2K TO 3K FT AND THE VERY DRY AIR UPSTREAM NORTH OF LAKE
SUPERIOR...WILL HELP SUPPRESS LAKE EFFECT SNOW CHANCES/INTENSITY
DESPITE TEMPS FCST NEAR -14C AT THE BASE OF THE INVERSION.
AS LAND BREEZES DEVELOP TONIGHT...INCREASING LOW LEVEL CONVERGENCE
SHOULD STRENGTHEN LES WITH SCT -SHSN INTO NORTH CENTRAL UPPER MI FROM
MARQUETTE TO MUNISING. ANY SNOWFALL AMOUNTS...HOWEVER SHOULD BE
LIGHT AMOUNTS OF A HALF INCH OR LESS. LAKE CLOUDS ARE EXPECTED TO
LIMIT TEMP FALL OVER CNTRL AND EAST PORTIONS OF THE CWA...BUT WITH
LIGHT/CALM WINDS AND SOME CLEARING INLAND WEST...TEMPS SHOULD DROP
INTO THE SINGLE DIGITS BLO ZERO...WITH SOME LOCALLY COLDER TEMPS
POSSIBLE.
SUNDAY...SIMILAR TO TODAY...EXPECT THAT LES IN THE MORNING MAINLY
INTO N CNTRL UPPER MI WILL DIMINISH IN THE AFTERNOON WITH THE SFC
RIDGE REMAINING OVER THE REGION. EXPECT MAX TEMPERATURES TO CLIMB
INTO THE MID AND UPPER 20S AS THE ARCTIC AIRMASS SLOWLY MODIFIES.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
TROUGH THAT HAS BEEN STUCK OVER THE GREAT LAKES THROUGH MOST OF THIS
PAST WEEK LOOKS TO FINALLY EASE BY MID-LATE WEEK. A MORE SIGNIFICANT
SHORTWAVE TROUGH DIGS INTO THE MEAN TROUGH MONDAY THROUGH WEDNESDAY.
BASED ON TRACK OF SHORTWAVE AND H85-H5 Q-VECTOR CONVERGENCE...MOST
OF THE SNOW FROM THAT SYSTEM WILL IMPACT MOST OF MINNESOTA THROUGH
WISCONSIN AND INTO LOWER MICHIGAN. EVEN THOUGH SFC-H85 LOWS REMAIN
WELL TO SOUTH OF UPR MICHIGAN...NORTHEAST WINDS BTWN THE LOWS AND
HIGH PRESSURE OVER HUDSON BAY AND ENOUGH LOW-LEVEL MOISTURE THROUGH
H9 ALONG WITH COLD ENOUGH TEMPS AT TOP OF INVERSION SHOULD SUPPORT
LIGHT LK EFFECT THROUGH WEDNESDAY BEFORE WINDS BECOME LIGHT AND
VARIABLE. SIMILAR TO WHAT WE HAVE SEEN LATELY THE SNOW WILL BE
AROUND BUT NOT ACCUMULATE MUCH AS INVERSION HEIGHTS REMAINING
BLO 3KFT LIMIT LK EFFECT INTENSITY AND MARGINALLY COLD AIR LIMITS
FLUXES OFF THE LAKES. INCREASING MOISTURE THROWN TO NORTH OF EARLY
WEEK LOW PRESSURE SYSTEM MAY HELP ENHANCE THE SNOW SLIGHTLY MONDAY
NIGHT AND TUESDAY IN AREAS FAVORED BY NORTHEAST WINDS. PERHAPS SOME
LIGHT SNOW ACCUMULATIONS OF A FEW INCHES MAY OCCUR DURING THAT TIME.
TEMPERATURES THROUGH WEDNESDAY WILL BE GRADUALLY WARMING...BUT STILL
ONLY INTO LOWER 30S. TRICKY FORECAST NIGHTTIME LOWS SUNDAY NIGHT AS
AREAS AWAY FROM THE CLOUDS AND SNOW SHOWERS NEAR LK SUPERIOR MAY
EASILY DROP BLO ZERO. MORE CLOUDS ON MONDAY NIGHT AND TUESDAY NIGHT
SHOULD RESULT IN READINGS STAYING MOSTLY IN THE TEENS ABOVE ZERO.
HIGH PRESSURE MOVING INTO THE AREA WEDNESDAY NIGHT WILL BEGIN TO
TURN WINDS TO THE SOUTH AND WILL FINALLY END LIGHT LK EFFECT BY
THURSDAY. BY FRIDAY...UPPER LEVEL TROUGH DEVELOPS FROM WESTERN
CONUS THROUGH NORTHERN PLAINS WHILE RIDGING MOVES ACROSS GREAT LAKES
IN WAKE OF THE EARLY WEEK SYSTEM. EXPECT LOW PRESSURE TO FORM ON
LEADING EDGE OF TROUGH OVER THE PLAINS...THOUGH THE STORM SHOULD NOT
BE TOO STRONG AS LOW-LEVEL TEMPERATURE CONTRAST PRECEEDING THE
SYSTEM IS MINIMAL. GFS AND ECMWF THEN SHOW TROUGH SPLITTING BY
FRIDAY WITH SOUTHERN STREAM PORTION CLOSING OFF OVER SOUTHWEST
CONUS WHILE NORTHERN BRANCH SHORTWAVE MOVES EAST ACROSS SOUTH
CENTRAL CANADA. NORTHERN TROUGH MOVING EAST WILL DRAG THE WEAKER LOW
PRESSURE SYSTEM AND ASSOCIATED COLD FRONT ACROSS GREAT LAKES LATER
ON FRIDAY. GFS REMAINS QUICKER WITH THIS COLD FROPA COMPARED TO
ECMWF AND GEM-NH. COULD BE SOME PRECIPITATION WITH THE SYSTEM...BUT
SINCE THE H85 LOW IS OPENING UP AND BECOMING MORE PROGRESSIVE...AND
MOVING THROUGH QUICKLY...DO NOT EXPECT SIGNIFICANT PRECIPITATION.
HAVING SMALL CHANCE POPS IN THERE FOR THURSDAY NIGHT THROUGH FRIDAY
NIGHT SEEM JUSTIFIED DURING THIS TIME FRAME.
AFTER THE PERSISTENT TROUGHING KEEPS TEMPS ON THE COOLER SIDE OF
AVERAGE TO START THE WEEK...EXPECT WARMER READINGS THURSDAY INTO
FRIDAY WITH SOUTH-SOUTHWEST WINDS BTWN THE HIGH PRESSURE AND THE LOW
PRESSURE SYSTEM TO THE WEST. BASED ON 925-900MB TEMPS...SHOULD SEE
HIGHS ON THURSDAY REACH THE 30S WITH JUST A SMALL DROP IN READINGS
ON THURSDAY NIGHT IN WARM AIR ADVECTION AHEAD OF THE COLD FRONT.
TEMPERATURES ON FRIDAY PROBABLY REACH WELL INTO THE 30S. IF NOT FOR
A MOSTLY CLOUDY SKY...COULD EVEN SEE A FEW LOW-MID 40S WHERE MIXING
IS STRONGER. DID TWEAK TEMPS UPWARD NEAR LK SUPERIOR WITH DOWNSLOPE
WINDS FCST. TIGHTER PRESSURE GRADIENT WILL LEAD TO BREEZY CONDITIONS
THURSDAY NIGHT AND FRIDAY. TURNING BLUSTERY FOR SATURDAY FOLLOWING
THE COLD FRONT PASSAGE. TEMPS WILL NOT DROP TOO MUCH THOUGH...MAINLY
STAYING IN THE LOW-MID 30S...WHICH IS NEAR NORMAL FOR EARLY MARCH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1250 AM EST SUN MAR 3 2013
DIFFICULT FORECAST CONTINUES WITH OFF AND ON AGAIN LAKE EFFECT
CLOUDS WITH NORTHERLY UPSLOPE DIRECTION CONTINUING. EACH
DAY...DIURNAL HEATING HAS MIXED OUT THE MVFR DECK WITH SOME DRIER
AIR. PERSISTENCE WITH THIS THEME WILL CONTINUE AT SAW AND CMX. VFR
CONDITIONS OVERNIGHT WILL BE REPLACED WITH THE MVFR CLOUDS
LATE TONIGHT AND THIS WILL LAST INTO SUN AFTERNOON BEFORE HEATING
AND MIXING AGAIN MIXES THIS LOW DECK BACK OUT. VFR CONDITIONS WILL
CONTINUE AT IWD THROUGH THE PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST SAT MAR 2 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WESTERN SECTIONS BY MONDAY NIGHT AS LOW
PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN MISSISSIPPI
RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK SUPERIOR
THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY WEDNESDAY.
WINDS INCREASE TO 25 KTS FROM THE SOUTH THURSDAY NIGHT AND FRIDAY
AHEAD OF COLD FRONT. NO GALES ARE EXPECTED THIS WEEK...THOUGH COULD
SEE GALE GUSTS OVER WESTERN LK SUPERIOR MONDAY NIGHT CLOSER TO
MINNESOTA SHORELINE DUE TO COASTAL CONVERGENCE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLA
AREA FORECAST DISCUSSION
NWS HASTINGS NE
942 PM CST MON MAR 4 2013
.UPDATE...DECIDED TO SEND AN UPDATE TO THE FORECAST TO SPEED UP
THE TIMING OF THE WIND ADVISORY IN SPOTS AS ORD HAS JUMPED TO
ADVISORY CRITERIA THE PAST HOUR AND HRRR IS INDICATING THESE
STRONG GUSTY WINDS WILL NOT RELAX MUCH...IF ANY...OVERNIGHT. OTHER
THAN INCREASING THE WIND FORECAST FOR THE OVERNIGHT HOURS...THE
REMAINDER OF THE FORECAST APPEARS TO BE ON TRACK AND NO ADDITIONAL
CHANGES WERE NECESSARY WITH THE UPDATE.
&&
.PREV DISCUSSION... /ISSUED 604 PM CST MON MAR 4 2013/
AVIATION...00Z KGRI TAF...WINDS WILL BE THE PRIMARY CONCERN OVER
THE THE NEXT 24 HOURS AS GUSTY NORTHWEST WINDS ARE EXPECTED TO
RETURN TO THE TERMINAL DURING THE EARLY MORNING HOURS TUESDAY.
OTHERWISE...EXPECT A FEW SPRINKLES OR VERY LIGHT RAIN SHOWERS TO
CONTINUE TO BE POSSIBLE AT KGRI FOR THE NEXT FEW HOURS WITH A MID
LEVEL CLOUD DECK AROUND 5KFT. CLOUDS WILL BEGIN TO CLEAR BEHIND
THE PASSING FRONT DURING THE MORNING HOURS TUESDAY...AND THEN
WINDS SHOULD REALLY INCREASE...GUSTING TO AROUND 36KT AFT 05/15Z.
PREV DISCUSSION... /ISSUED 316 PM CST MON MAR 4 2013/
SHORT TERM...(TONIGHT THROUGH TUESDAY) ISSUED AT 307 PM CST MON
MAR 4 2013
FOCUS DURING THE SHORT TERM PERIODS IS ON WINDS.
WATER VAPOR IMAGERY INDICATES A CLOSED UPPER LOW PRESSURE SYSTEM IN
THE WESTERN DAKOTAS...SHORTWAVE RIDGING IN THE PACIFIC NORTHWEST
WITH AN UPSTREAM UPPER LOW STILL OUT IN THE PACIFIC. AT THE SURFACE
LOW PRESSURE CENTERS WERE LOCATED IN SOUTH CENTRAL NORTH DAKOTA AS
WELL AS EASTERN OK. THE INITIAL COLD FRONTAL BOUNDARY WHICH CROSSED
OUR REGION OVERNIGHT WAS LOCATED FM EASTERN KS TO THE OK
PANHANDLE...WITH THE SECONDARY STRONGER COLD FRONT STRETCHING FROM
WESTERN SD TO SW NEB EARLY THIS AFTN.
NORTHWEST WINDS WERE STEADY/GUSTY ESPECIALLY THIS MORNING IN A TIGHT
PRESSURE GRADIENT FOLLOWING THE PASSAGE OF COLD FRONT
OVERNIGHT/COLD FRONT NUMBER ONE. THE SFC GRADIENT HAS RELAXED SOME
THIS AFTN WITH SOME DECREASE IN WIND SPEEDS NOTED. THE DEEPER
MIXING TODAY HAS ALLOWED TEMPS TO CLIMB TO THE MID/UPPER 40S. RADAR
RETURNS HAVE BEEN PICKING UP ON MID CLOUD COVER BUT RETURNS HAVE
ENHANCED THE LAST SEVERAL SCANS. ISOLATED SHOWERS/SPRINKLES ARE
NOT OUT OF THE QUESTION ESPECIALLY ACROSS THE SOUTHERN HALF OF OUR
CWA IN PRESENCE OF MID LEVEL FRONTOGENESIS AND LIFT ENHANCED AS
ENERGY ROUNDS BASE OF TROUGH...WHILE UPPER LOW TRANSLATES SE. LOW
POPS FOR ISOLATED -SHRA HAVE BEEN MAINTAINED THRU THE EVENING AND
FIRST PART OF THE NIGHT.
HEADING INTO TONIGHT...A STRONGER COLD FRONT/COLD FRONT NUMBER TWO
SWEEPS SOUTHEAST AFTER DARK WITH 6HR PRESSURE RISES AVERAGING 5 TO
7MB INITIALLY BEHIND THE FRONT. FORECAST SOUNDINGS MIX OUT LLVL
INVERSION AFTER 06Z AND ALTHOUGH COULD SEE SOME STRONG WINDS WITH
FROPA...LOOKING AT MORE SUSTAINED GUSTY WINDS HEADING INTO THE
OVERNIGHT TIME FRAME ON THE BACK SIDE OF THE UPPER LOW WHICH IS
PROGGED TO BE NEAR NE NEB 12Z TUESDAY. WITH INCREASING NW WINDS
TONIGHT AND WINDS REMAINING STRONG/GUSTY THRU AT LEAST THE FIRST
PART OF THE DAY ON TUESDAY...WILL GO AHEAD WITH A WIND ADVISORY
FOR OUR NORTHERN/EASTERN ZONES WHERE GRADIENT WILL BE TIGHTER IN
PROXIMITY TO THE LOW AND FORECAST SOUNDINGS INDICATE MIXING
BETWEEN H825 AND H85 WITH WINDS AT THE TOP OF THE LAYER AOA 40KTS.
SREF WIND PROBS INDICATE DECENT CHCS FOR REACHING WIND ADV
CRITERIA AND MOS GUIDANCE ALSO INDICATES POTENTIAL FOR NEAR/ABOVE WIND
ADV WINDS FOR SEVERAL HOURS. WIND SPEEDS IN OUR WESTERN ZONES MAY
DROP OFF EARLIER IN AFTN THAN HEADLINE INDICATES BUT PREFER TO
HAVE A ROW OF COUNTIES AS A BUFFER ACROSS OUR WEST/SOUTH ATTM. IN
CAA TUESDAY...GENERALLY EXPECT HIGHS TO AVERAGE IN THE MID/UPPER
30S. PCPN CHCS TUESDAY LOOK TO FAVOR LOCATIONS EAST OF OUR CWA
WHERE SOME FLURRIES/LIGHT SNOW SHOWERS ARE NOT OUT OF THE
QUESTION.
LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 307 PM CST MON
MAR 4 2013
TUESDAY NIGHT THROUGH MONDAY. MAIN FORECAST CONCERNS
WILL BE PRECIPITATION CHANCES FOR THE WEEKEND AND TEMPERATURES
THROUGH THE PERIOD.
AN UPPER LEVEL RIDGE IN THE WESTERN CONUS WILL DRIFT TO THE EAST
TUESDAY NIGHT THROUGH THURSDAY NIGHT. DURING THIS TIME A SURFACE
HIGH WILL MOVE TO THE EAST TUESDAY NIGHT WITH A TIGHTENING SURFACE
PRESSURE GRADIENT AS A SURFACE LOW DEVELOPS TO THE WEST. SOUTH WINDS
WILL INCREASE ACROSS THE AREA ON WEDNESDAY AND WILL CONTINUE THROUGH
THURSDAY NIGHT. EXPECT SOME BREEZY CONDITIONS...BUT MOST MODELS ONLY
HAVE 30 TO 35 KNOTS AT 850 MB SO DO NOT EXPECT VERY STRONG WINDS.
WITH THE SOUTH WINDS...SOME WARM ADVECTION AND THE UPPER RIDGE
MOVING THROUGH THE AREA...TEMPERATURES WILL BE WARMER AGAIN WITH
WARMER TEMPERATURES ON THURSDAY THAN WEDNESDAY.
THURSDAY NIGHT INTO FRIDAY THERE IS AN UPPER LEVEL WAVE THAT MOVES
INTO THE RIDGE AND THE SURFACE LOW AND COLD FRONT MOVE INTO THE
AREA. EXPECT AN INCREASE IN THE CLOUDS BUT TEMPERATURES WILL BE A
LITTLE COOLER IN THE NORTH BUT ABOUT THE SAME FOR THE SOUTH.
THE MODELS TAKE ON SOME FAIRLY SIGNIFICANT DIFFERENCES FOR THE
EXTENDED PERIOD. SOME OF THE DIFFERENCES START EVEN ON FRIDAY. AN
UPPER LOW PRESSURE SYSTEM WILL BE MOVING INTO THE PLAINS AND BRING A
CHANCE FOR PRECIPITATION TO THE AREA FROM FRIDAY NIGHT INTO MONDAY.
THE GFS IS MORE PROGRESSIVE WHILE THE LATEST RUN OF THE ECMWF SLOWS
THE CLOSED LOW DOWN AND LINGERS IT TO THE WEST WHILE THE GFS PUSHES
IT THROUGH INTO THE GREAT LAKES BY MONDAY EVENING. EXPECT THERE TO
BE PRECIPITATION STARTING FRIDAY NIGHT. THE BEST CHANCE WILL BE
SATURDAY AND SATURDAY NIGHT. HAVE LESS CHANCES FOR SUNDAY THROUGH
MONDAY. THE NEXT QUESTION WILL BE PRECIPITATION TYPE. TEMPERATURES
ARE FAIRLY WARM FRIDAY NIGHT THROUGH SUNDAY AND THERE IS A LITTLE
INSTABILITY SO HAVE WENT WITH SHOWERS. THE GFS HAS UP TO 300 J/KG.
THERE COULD BE AN ISOLATED LIGHTNING...BUT IT IS JUST A SMALL CHANCE
AND WITH THE MODELS HAVING SO MANY DIFFERENCES WILL JUST KEEP
SHOWERS. BY SUNDAY NIGHT THERE IS SOME COOLER AIR MOVING INTO THE
AREA AND THERE COULD BE SOME RAIN OR SNOW MIXED FOR SUNDAY NIGHT
INTO MONDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 4 AM TO 3 PM CST TUESDAY FOR NEZ041-048-049-
062>064-074>077.
WIND ADVISORY UNTIL 3 PM CST TUESDAY FOR NEZ039-040-046-047-061.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
541 PM CST MON MAR 4 2013
.AVIATION...00Z TAFS FOR KOFK...KLNK AND KOMA.
AREAS OF MVFR CIGS NEAR KLNK AND KOMA CAN BE EXPECTED THROUGH THE
EVENING. LIGHT RAIN OR SNOW MAY AFFECT THOSE TAF SITES AS WELL.
OTHERWISE A COLD FRONT SWEEPING THROUGH EASTERN NEBRASKA WILL
INCREASE NORTHWEST WINDS INTO THE 15 TO 25KT RANGE BY 06Z...WITH
FURTHER INCREASES INTO THE 25 TO 35KT RANGE AROUND 15Z TUESDAY.
MVFR CIGS WILL LIKELY ACCOMPANY THE STRONG WINDS TUESDAY. THE
WINDS WILL SLOWLY DECREASE LATE IN THE TAF PERIOD.
DERGAN
&&
.PREV DISCUSSION... /ISSUED 335 PM CST MON MAR 4 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY
THE PRIMARY FORECAST CONCERNS DURING THIS PERIOD ARE PCPN AND WINDS
TONIGHT...WINDS ON TUESDAY AND POTENTIAL FOR CLOUD COVER FOR TUESDAY
NIGHT.
CLOSED LOW AT 500 MB WHICH WAS OVER EXTREME EASTERN MONTANA AT 12Z
WILL CONTINUE TO DIVE SOUTHEAST TONIGHT...REACHING THE BORDER AREA
OF SOUTH DAKOTA/MINNESOTA/IOWA BY 12Z TUESDAY AND THEN SOUTHERN
ILLINOIS BY 00Z WEDNESDAY. SURFACE ANALYSIS EARLY THIS AFTERNOON
SHOWED ONE LOW PRESSURE CENTER OVER SOUTH CENTRAL NORTH DAKOTA AND
ANOTHER OVER OKLAHOMA. AN INVERTED TROF EXTENDED NORTHWARD FROM
THE SOUTHERN LOW. NORTHERN LOW WILL PUSH SOUTHEAST AND WEAKEN
OVERNIGHT. FAIRLY TIGHT PRESSURE GRADIENT OVER THE AREA ALONG WITH
DECENT DOWNWARD MOMENTUM TRANSFER SHOULD RESULT IN GUSTY WINDS
LATER TONIGHT AND INTO TUESDAY. WILL LEAVE PREVIOUSLY ISSUED WIND
ADVISORY IN PLACE BUT EXTEND IT UNTIL 21Z. THIS CAN BE CANCELED IS
WINDS DECREASE EARLIER. ALSO ISSUED ANOTHER WIND ADVISORY SEGMENT
TO THE SOUTHEAST OF PREVIOUS ADVISORY FROM 8 AM TO 3 PM
TUESDAY...AS STRONGER WINDS OVERSPREAD MORE OF THE AREA.
RADAR ECHOES HAVE BEEN INCREASING TO OUR WEST...WITH SOME LIGHT SNOW
REPORTED IN PARTS OF SOUTHWEST NEBRASKA. RECENT HRRR AND RAP13 MODEL
RUNS INDICATE SOME PCPN WILL DEVELOP OVER ABOUT THE SOUTHEAST HALF
OF THE FORECAST AREA THIS EVENING...IN ASSOCIATION WITH 500-300 MB
Q VECTOR DIVERGENCE AND ELEVATED FRONTOGENESIS. RAP13 PCPN
AMOUNTS SEEM OVERDONE...BUT SCENARIO IS ALSO SUPPORTED BY 18Z NAM.
ON TUESDAY...FAIRLY TIGHT PRESSURE GRADIENT IS IN PLACE DURING THE
MORNING BUT THIS RELAXES IN THE AFTERNOON. THERE IS SOME SMALL
POTENTIAL FOR LIGHT SNOW TUESDAY...MAINLY FOR ABOUT THE NORTHEAST
ONE THIRD OF THE FORECAST AREA...BUT CHANCES ARE MUCH HIGHER FARTHER
TO THE EAST OF OUR AREA.
OTHERWISE...LOOK FOR MAINLY DRY CONDITIONS TUESDAY NIGHT AS HIGH
PRESSURE BUILDS IN. SOME MODELS SHOW LOW LEVEL MOISTURE MOVING INTO
THE AREA FROM THE NORTH...SO WILL HAVE TO WATCH THAT. FOR NOW...
HAVING CLEARING SKIES. THAT SURFACE RIDGE WILL PUSH OFF TO THE EAST
WEDNESDAY THROUGH THURSDAY WITH INCREASING SOUTH/SOUTHEAST WINDS...
MODERATING TEMPERATURES AND MAINLY DRY CONDITIONS.
MILLER
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
CONFIDENCE IS INCREASING THAT THE UPPER LEVEL LOW THAT WILL DIVE
INTO THE SOUTHWEST CONUS ON WED/THU WILL MOVE INTO THE PLAINS AT
SOME POINT NEXT WEEKEND. THE ECMWF/GEM HAVE REMAINED VERY CONSISTENT
OVER THE PAST COUPLE OF DAYS WHILE THE OPERATIONAL GFS HAS VARIED
WILDLY FROM THE 00Z/04 TO 12Z/O4 RUNS. THUS WILL LEAVE MUCH HEAVIER
ON THE EC/GEM/EC ENSEMBLE SOLUTIONS FOR THE TRACK OF THIS SYSTEM.
AHEAD OF THE SYSTEM/COLD FRONT WE SHOULD SEE A NICE DAY ON FRIDAY
WITH HIGHS ABOVE SEASONAL AVERAGES. THE COLD FRONT THEN MOVES
THROUGH THE FA ON THE WEEKEND WITH SLIGHTLY COOLER AIR MOVING INTO
THE REGION. THE GFS...ALTHOUGH CLOSER TO THE EC WITH THE 12Z/04
RUN...IS STILL TO FAST IN BRINGING PRECIP TO THE AREA. WILL HOLD
ONTO SOME POPS IN THE SW ON FRI NIGHT...BUT IT WILL LIKELY BE SAT OR
MAYBE EVEN SAT NIGHT BEFORE WE SEE THE BULK OF THE PRECIP ASSOCIATED
WITH THE UPPER LEVEL LOW HEAD INTO THE PLAINS.
THE EC IS VERY WARM FOR THIS SYSTEM AND WOULD HAVE LIMITED CHANCE OF
ANY FROZEN PRECIP AT ALL FOR OUR FA...AND WE WILL TREND THE FORECAST
THIS WAY. HAVE INCREASED OVERNIGHT LOWS AS WELL AS HIGHS A TOUCH FOR
MOST AREAS. REMOVED FZRA MENTION AND WENT WITH A RA/SN MIX IN THE
FAR NORTH AND OTHERWISE JUST RA OVER THE SRN 2/3RD OF THE FA. IT IS
IMPORTANT TO NOTE THAT THE FORECAST WILL HAVE CHANCES OF PRECIP FOR
SEVERAL PERIODS...BUT THIS MORE REFLECTS THE UNCERTAINTY IN THE
TIMING MORE THAN WE WILL HAVE CONTINUOUS RAIN OVER A 48 HOUR
PERIOD.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 8 AM TO 3 PM CST TUESDAY FOR NEZ015-032>034-
042>045-050-051-065-066-078.
WIND ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST TUESDAY FOR
NEZ011-012-016>018-030-031.
IA...WIND ADVISORY FROM 8 AM TO 3 PM CST TUESDAY FOR IAZ043.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
926 PM CST MON MAR 4 2013
.DISCUSSION...
MAIN FORECAST HEADACHE REMAINS WHAT TO DO WITH HEADLINES. SOUTHERN
COUNTIES HAVE SEEN THE DRY SLOT FOR MUCH OF THE EVENING...WITH
PLACES SUCH AS FERGUS FALLS ONLY REPORTING AN INCH OF SNOW AND NO
SNOW FALLING CURRENTLY. ON THE OTHER HAND...THERE HAVE BEEN SOME
REPORTS OF FREEZING DRIZZLE AND SLICK ROADS IN THE FAR SOUTHERN
CWA. WRAP AROUND SNOW IS STILL MAKING ITS WAY THROUGH CENTRAL ND
AND MAY DROP ANOTHER 1-3 INCHES. AREAS AROUND VALLEY CITY AND
FARGO MAY NOT GET THE 6-8 INCHES NEEDED FOR WARNING CRITERIA.
HOWEVER...THINK THERE HAS BEEN ENOUGH FREEZING DRIZZLE AND WITH
WINDS PICKING UP AFTER MIDNIGHT AND CREATING SOME BLOWING SNOW
ISSUES THINK THAT WE MAY STILL REACH THE GRAND FORKS SPECIAL
CRITERIA OF FOUR INCHES WITH ADDITIONAL MIXED PRECIP AND BLOWING
SNOW. WILL KEEP THE WARNING GOING FOR NOW IN THE FARGO/VALLEY CITY
AREA...BUT TRIM IT A BIT MORE IN THE PARTS OF THE SOUTHEAST WHERE
SNOW AMOUNTS WILL STRUGGLE TO REACH EVEN FOUR INCHES. CHANGED
GRANT AND WESTERN OTTERTAIL OVER TO ADVISORY. NAM AND RAP CONTINUE
TO SHOW THE PRECIP BAND STRENGTHENING OVER THE FAR EASTERN
COUNTIES AND IT HAS CONTINUED TO SNOW AROUND WADENA AND PKD...SO
WILL KEEP WARNING GOING FOR THOSE LOCATIONS. FURTHER NORTH THERE
WILL CONTINUE TO BE ANOTHER FEW INCHES ON TOP OF ALREADY WARNING
LEVEL SNOW.
&&
.AVIATION...
MOST LOCATIONS WILL CONTINUE TO SEE MVFR OR LOWER CEILINGS. A FEW
SITES MAY BRIEFLY HAVE VFR VISIBILITIES DURING THE NEXT FEW HOURS BUT
THAT SHOULD END AS THE WRAP AROUND SNOW BAND MOVES INTO THE AREA.
VIS OVERNIGHT SHOULD DROP INTO THE 1 TO 4SM RANGE. THINK THAT THE
LOWEST VIS OF LESS THAN A MILE SHOULD BE BRIEF AND SPOTTY SO DID
NOT INCLUDE AT THE TAFS AT THIS POINT. CONDITIONS SHOULD BEGIN TO
IMPROVE AT THE END OF THE PERIOD AS SNOW MOVES OFF TO THE EAST.
&&
.PREV DISCUSSION... /ISSUED 310 PM CST MON MAR 4 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY
CHALLENGES ABOUND WITH ONGOING WINTER STORM...OF GREATEST CONCERN
WILL BE SNOW AMOUNTS AND ASSOCIATED HEADLINES. MODELS CONTINUE TO
UNDERESTIMATE THE STRENGTH OF THE DRYING FROM BOTH THE DRY SLOT TO
THE SOUTH AND ARCTIC HIGH TO THE NORTH. OVERALL...RAP SEEMS TO
HAVE THE BEST HANDLE ON REALITY AND WILL FOLLOW ITS OUTPUT AND
THE LATEST OBSERVATIONAL TRENDS FOR THE NEXT SEVERAL HOURS.
SURFACE LOW AS OF 21 UTC HAS FINALLY TURNED TO THE SOUTH...
CENTERED TO THE SOUTHEAST OF BISMARCK BY ABOUT 50 MILES. RAP SHOWS
THE SURFACE LOW CONTINUING ITS SOUTHEASTWARD TRACK...NEARING
ABERDEEN BETWEEN 03 AND 06 UTC THIS EVENING. MODERATE TO HEAVY
SNOW BAND FROM MINOT TO GRAND FORKS TO DETROIT LAKES WILL CONTINUE
TO PIVOT AROUND THE LOW...IMPACTING MOST OF THE FORECAST AREA
THIS EVENING AND THROUGH THE NIGHT. THE DRY SLOT HAS MOVED INTO
EASTERN ND ALONG AND WEST OF A LINE FROM DEVILS LAKE TO GRAND
FORKS TO FARGO AND EXPECT A BREAK IN SNOWFALL IN THIS AREA LATE
THIS AFTERNOON AND EVENING BEFORE LIGHT WRAP-AROUND SNOW MOVES
THROUGH IN THE WAKE OF THE SURFACE LOW.
HIGHEST SNOW TOTALS SO FAR HAVE BEEN ALONG AND SOUTH OF THE
CANADIAN BORDER ACROSS THE DEVILS LAKE BASIN AND INTO THE NORTHERN
VALLEY WHERE OVER A FOOT HAS ACCUMULATED. FARTHER SOUTH AND EAST
FROM EAST CENTRAL ND INTO THE CENTRAL VALLEY HAS RECEIVED 5 TO 8
INCHES. VERY LITTLE SNOW HAS FALLEN SO FAR FROM FERGUS FALLS TO
DETROIT LAKES/PARK RAPIDS NORTHWARD TO BEMIDJI AND ROSEAU/
BAUDETTE WITH ONLY AN INCH OR LESS ACCUMULATION. RAP SUGGESTS THIS
AREA WILL FILL-IN THIS EVENING AND OVERNIGHT AS THE SURFACE LOW
MOVES INTO SD AND SOUTHWEST MN. AS A RESULT...WILL KEEP WINTER
STORM WARNING IN PLACE FOR THESE AREAS WITH SNOW TOTALS BY TUESDAY
MORNING IN THE 4 TO 7 INCH RANGE. BACK TO THE NORTH AND WEST
ANOTHER 1 TO 4 INCHES ARE POSSIBLE OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ALONG AND WEST OF THE VALLEY LATE
THIS EVENING AND OVERNIGHT. ALTHOUGH NOT OVERLY STRONG...WIND
SPEEDS SHOULD BE HIGH ENOUGH FOR PERIODS OF BLOWING AND DRIFTING
SNOW AND WILL INCLUDE THIS IN THE GRIDS. WITH CLOUD COVER AND WIND
OVERNIGHT...EXPECT ELEVATED TEMPERATURES WITH TUESDAY MORNING LOWS
IN THE MID TO UPPER TEENS.
LIGHT SNOW WILL LINGER EAST OF THE VALLEY THROUGH TUESDAY MORNING
AND DEPENDING ON HOW MUCH SNOW ACCUMULATES OVERNIGHT...THE WINTER
STORM WARNING MAY NEED TO BE EXTENDED. FOR AREAS TO THE WEST...
EXPECT VERY GRADUAL DRYING AND CLEARING. HIGHS TOMORROW WILL RANGE
FROM THE UPPER TEENS TO MID 20S.
WEDNESDAY WILL BE DRY WITH PERIODS OF SUNSHINE AS SURFACE HIGH
PRESSURE BUILDS ACROSS THE REGION. WILL MAINTAIN 20 TO 30 POPS
ACROSS THE NORTH ON THURSDAY AS A SHORT-WAVE MOVES THROUGH
SOUTHWEST FLOW ALOFT. HOWEVER...LATEST MODEL TRENDS PLACE THE
MAJORITY OF SNOW NORTH OF THE BORDER...SO NOT EXPECTING MUCH IN
THE WAY OF ACCUMULATION. BY THURSDAY...TEMPERATURES WILL RISE INTO
THE UPPER 20S TO LOW 30S.
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
SW FLOW ALOFT IS EXPECTED TO BEGIN THE PERIOD...WITH THE CHANCE OF
SOME SNOW THU NIGHT. THEREAFTER...THE FLOW BECOMES SOMEWHAT
SPLIT...ALTHOUGH MODELS DIFFER ON JUST HOW MUCH INFLUENCE A SOUTHERN
STREAM WAVE MAY HAVE LATER IN THE WEEKEND. FOR NOW WILL KEEP SOME
LOW POPS THU NIGHT...THEN AGAIN LATER IN THE WEEKEND INTO EARLY NEXT
WEEK FOR MAINLY THE SOUTHERN AREAS. TEMPS SHOULD MODERATE TO NEAR
NORMAL THIS WEEKEND...WITH OVERALL CONFIDENCE NOT VERY HIGH WITH
THIS FORECAST.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR NDZ049-052-
053.
WINTER STORM WARNING UNTIL 6 AM CST TUESDAY FOR NDZ006>008-
014>016-024-026>030-038-039-054.
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR MNZ029-030-
040.
WINTER STORM WARNING UNTIL 6 AM CST TUESDAY FOR MNZ001>009-
013>017-022>024-027-028-031-032.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS BISMARCK ND
515 PM CST MON MAR 4 2013
.DISCUSSION...QUICK UPDATE TO EXPAND THE BLIZZARD WARNING SOUTH
AND FURTHER EAST. LATEST RAP MODEL AND CURRENT SURFACE OBS/RADAR
CONFIRM TRENDS OF SNOW BANDS COINCIDING WITH A PERIOD OF STRONG/GUSTY
WINDS TO 45 MPH THIS EVENING THROUGH MIDNIGHT SOUTHWEST THROUGH
SOUTH CENTRAL. WE DECIDED TO UPGRADE TO A BLIZZARD WARNING IN
EXPECTATIONS THAT VISIBILITIES WILL FALL TO AROUND/BELOW ONE
QUARTER MILE FOR AT LEAST THREE HOURS THIS EVENING. UPDATES ARE
BEING SENT OUT NOW.
&&
.AVIATION...MAIN HAZARD TO AVIATION WILL CONTINUE TO BE THE SNOW
AND BLOWING SNOW...WITH BLIZZARD CONDITIONS WITH WINDS GUSTING TO
OVER 40 KTS FROM WILLISTON TO NEAR BEACH. THIS WILL CONTINUE
THROUGH THE EARLY EVENING. IFR CONDITIONS WILL CONTINUE OVER
KJMS/KMOT. CONDITIONS WILL DETERIORATE AGAIN TO IFR/LIFR IN SNOW
AND BLOWING SNOW FROM WEST TO EAST (KDIK/KBIS/KJMS) THIS AFTERNOON
AND EVENING. CONDITIONS SHOULD IMPROVE TO MVFR/VFR FROM WEST TO
EAST AFTER MIDNIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WARNING UNTIL 9 PM CST /8 PM MST/ THIS EVENING FOR
NDZ001-002-009-010-017>020-031>034-040>045.
WINTER STORM WARNING UNTIL 6 AM CST TUESDAY FOR NDZ003>005-
011>013.
WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR NDZ023-025-
036-037-047-048-050-051.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR NDZ021-
022-035-046.
BLIZZARD WARNING UNTIL MIDNIGHT CST TONIGHT FOR NDZ021-022-035-046.
&&
$$
DISCUSSION...KS
AVIATION...NH
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1037 AM CST SUN MAR 3 2013
.DISCUSSION...
16 UTC WATER VAPOR LOOP SHOWS A STRONG UPPER LOW MOVING ALONG THE
NORTHWEST MT/CANADIAN BORDER WHILE ITS SURFACE LOW IS TAKING SHAPE
IN THE LEE OF THE NORTHERN ROCKIES. REGIONAL RADARS SHOW A BAND OF
WEAK ECHOES FROM BRANDON MB TO VALLEY CITY WITH SOME EMBEDDED
HIGHER REFLECTIVITY AROUND 20 DB. SURFACE OBSERVATIONS BENEATH THE
STRONGEST ECHOES NOT REPORTING SNOW...BUT DEVILS LAKE WEBCAMS DO
SHOW SOME FLURRY ACTIVITY. THINK THIS AREA IS IN RESPONSE TO THE
LEADING EDGE OF MID-LEVEL MOISTURE AND SOME WEAK ISENTROPIC LIFT.
ADDED A NARROW BAND OF 20 POPS WEST OF A LINE FROM LANGDON TO
VALLEY CITY FOR A STRAY TENTH OF ACCUMULATION. OTHERWISE...INCLUDED
FLURRY MENTION ALONG AND WEST OF THE VALLEY THROUGH THE EARLY
AFTERNOON. WILL ALSO MENTION PATCHY FOG THROUGH THE REST OF THE
MORNING ACROSS THE DEVILS LAKE BASIN WITH REDUCTIONS IN VISIBILITY
DOWN TO 1 SM.
QUITE THE GRADIENT IN MOISTURE ACROSS THE NORTHERN PLAINS TODAY
COMPARING THE 12 UTC BIS/INL RABOS. SURFACE DEW POINT TEMPERATURES
RANGE FROM THE UPPER 20S TO LOWER 30S ACROSS THE CENTRAL DAKOTAS
TO THE SINGLE DIGITS ABOVE/BELOW ZERO ACROSS THE MN ARROWHEAD. IT
WILL TAKE SOME TIME FOR THE LOW-MID LEVELS TO SATURATE AND THIS IS
REFLECTED IN LATEST RAP/SREF MODEL RUNS WHICH SHOW MAJORITY OF
SNOW HOLDING OFF UNTIL AFTER 21 TO 00 UTC LATE THIS AFTERNOON AND
EVENING. WILL MAKE MINIMAL POP/WX CHANGES AT THIS TIME WITH MOST
SNOW MOVING INTO EASTERN ND AFTER 00 UTC AND PERHAPS NOT INTO THE
VALLEY UNTIL THE MIDNIGHT HOUR OR LATER. WILL NEED TO MAKE A
DECISION ON THE REMAINING WINTER STORM WATCH THIS AFTERNOON...BUT
FOR NOW WILL WAIT FOR THE FULL SUITE OF 12 UTC GUIDANCE AND NOT
MAKE ANY HEADLINE CHANGES.
&&
.AVIATION...
LIFR/IFR CONDITIONS AFFECTING KDVL TRANSITION TO MVFR OVER KGFK...
AND VFR FOR THE REMAINDER OF THE TAF SITES. RAP GUIDANCE SUGGESTS
NOT MUCH CHANGE WITH THESE CONDITIONS THROUGH THE REMAINDER OF THE
DAY...EXCEPT SLIGHTLY IMPROVING CONDITIONS. LATER TONIGHT...EXPECT
LOWERING CONDITIONS WITH THE APPROACH OF THE WINTER STORM.
&&
.PREV DISCUSSION... /ISSUED 332 AM CST SUN MAR 3 2013/
SHORT TERM...
FOR THIS UPCOMING STORM SYSTEM 00Z GFS CAME IN WITH A MORE NRN
SOLN MORE SIMILAR TO ECMWF/NAM AND 00Z GEM CAME WITH A MORE
SIMILAR SOLN AS WELL. THUS CONFIDENCE IN HEAVIEST SNOW AREA IS
HIGHER. 500 MB WAVE MOVING THRU SRN-CNTRL BRITISH COLUMBIA ATTM
WITH QUITE COLD AIR ALOFT WITH SYSTEM AS NOTED BY LIGHTENING
STRIKES IN SOUTHERN B.C. ALSO GOOD MOISTURE PLUME AHD OF UPPER LOW
FROM OFF THE SRN CALIFORNIA COAST INTO MONTANA. MODELS LESS
DISAGREEMENT TONIGHT WITH GENERAL IDEA IS TAKING UPPER LOW TOWARD
GLACIER PARK 00Z MON THEN INTO EITHER SOUTH CENTRAL ND OR CENTRAL
SD BY 00Z TUES. 00Z ECMWF IS CLOSER TO 00Z NAM IN BEING FARTHER
NORTH WHILE 00Z GFS/GEM IS STILL A BIT FARTHER SOUTH. SFC LOW
TRACK WOULD HAVE IT FROM NCNTRL MT INTO SOUTHWEST ND THEN INTO
NORTH CENTRAL SD BY 00Z TUE THEN TOWARD SIOUX FALLS BY 06Z TUES.
GFS/ECMWF HAS VERY STRONG UPPER LEVEL SUPPORT WITH THIS SYSTEM
WITH GOOD JET DYNAMICS AND STRONG 500-300 MB DIV Q AND QUITE
STRONG 850-700 QG FORCING OVER MOST OF ND INTO MN WITH THIS
FEATURE. USING ISENTROPIC 285K SURFACE SHOWS A GOOD 24 HR PERIOD
OF 3-3.5 G/KG MOISTURE AND LIFT INTO ERN ND AND WRN MN WITH THIS
SYSTEM. MODEL QPF FCSTS SHOWS PERHAPS THE HIGHEST QPF MOVING INTO
PARTS OF CNTRL-SE ND 00Z-06Z MON PERIOD THEN LIFTING NORTH INTO
THE NRN VALLEY 06Z-18Z MON PERIOD. ALL MODELS SHOW A WIDESPREAD 8
TO 12 INCH AMOUNT OF SNOW OVER ALL OF NRN INTO ERN ND INTO NW-
WCNTRL MN WITH ISENTROPIC LIFT CHARTS INDICATING BEST CHC OF FOOT
AMOUNTS OR A TAD MORE ECNTRL ND INTO DVL BASIN.
BASED ON HIGHER CONFIDENCE OF EVENT WILL GO WITH WINTER STORM
WARNINGS FOR 00Z MON-12Z TUE FOR ALL OF ERN ND INTO FAR WRN MN
(HCO-FSE-DTL-ADC WEST). WILL KEEP OR EXPAND WINTER STORM WATCHES A
BIT INTO PARK RAPIDS-BEMIDJI-ROSEAU AREAS AS MANY MODELS SHOW THEM
GETTING 6-8. START TIME OF SNOW THERE PAST 06Z MON SO HAVE TIME TO
UPGRADE IF NEED BE. COORD WITH WFO DLH.
WIND WITH SYSTEM WILL NOT BE A HUGE ISSUE...WILL HAVE A SOUTHEAST
OR EAST WIND 10 TO 20 KTS AHD OF SYSTEM THEN TURN NORTH TUESDAY.
COULD BE SOME GUSTS HIGHER. RATE OF SNOWFALL THOUGH AT TIMES LATER
TONIGHT INTO MONDAY MORNING COULD BE QUITE HVY SO CONTINUED
MENTION OF +SN IN GRIDDS IN MUCH OF ERN ND.
SYSTEM WILL EXIT TUESDAY MORNING.
LONG TERM...WEDNESDAY THROUGH SATURDAY
IN WAKE OF DEPARTING STORM CWFA UNDER HIGH PRESSURE SURFACE AND
ALOFT AT THE START OF THE LONG TERM. LIGHT SFC WINDS EARLY EXPECTED
TO BEGIN INCREASING AS NEXT SYSTEM FORECAST TO BE DEVELOPING IN
WYOMING OR MONTANA. CURRENT MODEL SUITE SHOWS THE TRANSITION TO
SOUTHWEST FLOW ALOFT COMPLETE BY THURSDAY.
MODELS HAVE CONTINUED TO VACILLATE BETWEEN SPLIT FLOW AND MORE
CONSOLIDATED FLOW. 18Z DGEX/00Z GFS SEEMS A BIT BULLISH WITH
STRENGTH OF LEAD SHORTWAVE. ALLBLENDS SHOW LOW POPS FOR THURSDAY
WITH GEM-HEMI SUPPORTING THIS. ECMWF NOT SO DISSIMILAR BUT HAS
PRECIP NORTH OF BORDER. DIFFERENCES ON FRIDAY ARISE AS GFS AND
GEMI-HEMI HAVE SHORTWAVE ENERGY AND LIGHT QPF LINGERING OVER
NORTHEAST FA FRIDAY. ECMWF HAS A SMATTERING OF LOW END QPF AS
WELL...SO CONSENSUS SUPPORTS THIS.
SURFACE HIGH PRESSURE BUILDS IN WITH DRYING COLUMN FOR THE END OF
THIS PERIOD.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST TUESDAY
FOR NDZ006>008-014>016-024-026>030-038-039-049-052>054.
MN...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST TUESDAY
FOR MNZ001>004-007-013>015-022-027>031-040.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE MONDAY NIGHT
FOR MNZ005-008-009-016-017-023-024-032.
&&
$$
ROGERS/TG/RIDDLE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
344 AM CST SUN MAR 3 2013
.SHORT TERM...TODAY THROUGH MONDAY NIGHT...
THE HIGHLIGHTS OF THE SHORT TERM ARE A SIGNIFICANT WINTER STORM
TODAY THROUGH MONDAY NIGHT AND DENSE FOG NORTH CENTRAL THIS MORNING.
DID EXTEND THE ONGOING DENSE FOG ADVISORY FOR THE TURTLE MOUNTAINS
AREA AND THE FAR UPPER JAMES RIVER VALLEY THROUGH 15 UTC AS THE
LATEST RUNS OF THE HRRR SUGGEST THE DENSE FOG WILL CONTINUE PAST
12 UTC. THIS SEEMS PLAUSIBLE GIVEN THE MOIST LOW LEVELS AHEAD OF
THE STORM AND WEAK MIXING THIS MORNING.
IN REGARDS TO THE WINTER STORM...THE 00 UTC DETERMINISTIC SUITE IS
IN GOOD AGREEMENT...AND USED A BLEND OF THE GFS/ECMWF/GEM/SREF FOR
ALL FIELDS THROUGH MONDAY NIGHT...WITH THE NAM EXCLUDED AS IT IS A
NORTHERLY OUTLIER WITH THE UPPER LEVEL LOW. LOW LEVEL ISENTROPIC
LIFT AND COUPLING OF FRONTOGENETIC AND UPPER LEVEL FORCING INCREASE
THROUGH LATE SUNDAY MORNING AND THE AFTERNOON. THUS...EXPECT TO
SEE A SLOW INCREASE IN PRECIPITATION THROUGH SUNDAY MORNING AND
INTO THE AFTERNOON. PRECIPITATION IS EXPECTED TO BEGIN AS ALL RAIN
ACROSS THE SOUTHWEST WITH ABOVE FREEZING TEMPERATURES THROUGH
APPROXIMATELY 800 MB. THE PREFERRED ZONE OF MIXED PHASE
PRECIPITATION FROM WILLISTON THROUGH BISMARCK AND WISHEK LATE
THIS MORNING AND EARLY AFTERNOON WILL SHIFT SOUTHWEST THROUGH THE
LATE AFTERNOON AND EARLY EVENING AS DYNAMIC COOLING AIDES IN
ERODING THE WARM LAYER ALOFT. THE AREA OF GREATEST CONCERN FOR
ICE ACCUMULATIONS...UP TO A TENTH OF AN INCH...IS FROM WATFORD
CITY THROUGH HEBRON AND FORT YATES WHERE THE WINDOW OF A WARM
LAYER NEAR +3 C RESIDES ABOVE SUB FREEZING SURFACE TEMPERATURES
THE LONGEST.
CONTINUED COUPLING OF LOW LEVEL AND UPPER LEVEL CIRCULATIONS
CONTINUE SUNDAY EVENING AND INTO MONDAY MORNING...WITH STRONG
OMEGA IN THE DENDRITIC GROWTH ZONE. A TEMPORARY LULL IN THE STORM
IS EXPECTED LATE SUNDAY NIGHT INTO MONDAY MORNING ACROSS THE
SOUTHWEST AND SOUTH CENTRAL AS A DRY SLOT WORKS INTO THE
AREA...WHICH WILL ACT AS A LIMITING FACTOR FOR HIGHER SNOWFALL
ACCUMULATIONS. SNOW ASSOCIATED WITH THE TROWAL CONTINUES MONDAY
AFTERNOON...WITH INTENSITIES DECREASING INTO MONDAY NIGHT. COLD
AIR ADVECTION ON THE BACKSIDE OF THE SYSTEM ON MONDAY SUPPORTS
MOMENTUM TRANSPORT WITH GUSTS OF 30-35 KTS POSSIBLE WEST OF
HIGHWAY 83. WILL HAVE TO MONITOR THIS AS BLIZZARD CONDITIONS COULD
BE APPROACHED. SEE THE WSW FOR SNOWFALL ACCUMULATION DETAILS...BUT
IN GENERAL...THE GREATEST SNOWFALL AMOUNTS OF 12 TO 15 INCHES ARE
FORECAST FOR THE FAR NORTHWEST AND NORTH CENTRAL...DECREASING TO 6
TO 8 INCHES SOUTH CENTRAL WITH 3 TO 5 OR LESS FOR THE SOUTHWEST.
.LONG TERM...TUESDAY THROUGH SATURDAY NIGHT...
NO SIGNIFICANT HIGHLIGHTS IN THE EXTENDED PERIOD.
FOLLOWING THE WINTER STORM SUNDAY THROUGH MONDAY NIGHT...EXPECT A
COOL DAY TUESDAY WITH HIGHS OF 15 TO 20 ALONG AND EAST OF THE
MISSOURI RIVER AND 20 TO 30 SOUTHWEST. AFTER THAT...AN UPPER LEVEL
RIDGE WILL BUILD EAST ACROSS THE NORTHERN PLAINS. MILD AND DRY
WEATHER WILL RETURN TO THE FORECAST AREA WEDNESDAY.
TEMPERATURES WILL BE NEAR OR SLIGHTLY WARMER THAN NORMAL...WITH
AFTERNOON HIGHS GENERALLY IN THE 20S AND 30S WEDNESDAY.
MEANWHILE A LONGWAVE TROUGH MOVES INTO THE WEST COAST WEDNESDAY AND
EXPANDS EASTWARD...RESULTING IN SOUTHWEST FLOW ALOFT OVER THE
NORTHERN PLAINS WITH SOME UPPER LEVEL ENERGY IMPULSES REACHING NORTH
DAKOTA ON THURSDAY. AT THE SAME TIME A SURFACE COLD FRONT MOVES
SOUTHWARD THROUGH THE STATE THURSDAY. THUS A CHANCE OF LIGHT SNOW
FOR THURSDAY AND THURSDAY NIGHT WITH LOWS THURSDAY NIGHT FROM 10 TO
20 DEGREES.
THE MEDIUM RANGE MODELS INDICATE THE LONGWAVE TROUGH CUTTING OFF
OVER THE SOUTHERN ROCKIES AND DESERT SOUTHWEST. THIS WOULD BRING A
PERIOD OF DRY WEATHER FOR NORTH DAKOTA FOR FRIDAY AND SATURDAY.
HOWEVER...WILL HAVE TO WATCH IN LATER MODEL RUNS TO SEE HOW THE
MODELS HANDLE THE CUTOFF SYSTEM. FOR NOW WILL KEEP THE FORECAST DRY
FOR FRIDAY AND SATURDAY WITH A WARMING TREND WITH HIGHS SATURDAY
MAINLY IN THE 30S AND 40S.
&&
.AVIATION...
A SURFACE LOW WAS OVER SOUTHERN ALBERTA AND A TROUGH EXTENDED FROM
THE LOW ACROSS EASTERN MONTANA TO ANOTHER LOW OVER EASTERN WYOMING
TO NORTHWESTERN SOUTH DAKOTA. VFR CIGS AND VSBYS MAINLY ALONG AND
SOUTH/WEST OF THE MISSOURI RIVER AT KDIK/KHEI/KISN/KBIS IN THE WARM
SECTOR WITH TEMPERATURES IN THE UPPER 20S TO 30S. EAST OF THE
MISSOURI IN THE COLDER SURFACE AIR WITH TEMPERATURES IN THE TEENS TO
LOWER 20S AT KMOT/KDVL IFR/LIFR CIGS AND VSBYS HAD DEVELOPED.
RUGBY/ROLLA/HARVEY ALSO LIFR...AND EXPECT KJMS TO BECOME IFR BEFORE
12Z.
AS THE STORM SYSTEM CONTINUES TO DEVELOP AND APPROACH NORTH
DAKOTA...CIGS WILL LOWER AT TAF SITES. A LIGHT WINTRY MIX WILL
BEGIN TO IMPACT KISN/KBIS/KMOT AFTER 12Z...WITH LIGHT RAIN FOR
KDIK/KHEI. PRECIPITATION WILL SPREAD EAST INTO KMOT AFTER 15Z AND
KJMS AFTER 18Z. A GRADUAL TRANSITION FROM A LIGHT WINTRY MIX/RAIN
TO MAINLY SNOW AND LOWERED VISIBILITIES TO IFR/LIFR WILL BE SEEN
AFTER 18Z FOR KBIS/KISN/KMOT/KJMS...WITH KDIK TRANSITIONING TO ALL
SNOW BETWEEN 21Z AND 00Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM NOON TODAY TO 6 AM CST TUESDAY FOR
NDZ001>005-009>013-017>023-025-034>037-046>048-050-051.
WINTER WEATHER ADVISORY FROM NOON CST /11 AM MST/ TODAY TO 6 AM
CST /5 AM MST/ TUESDAY FOR NDZ031>033-041-042-045.
DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR NDZ004-005-
012-013-022-023-025.
&&
$$
SHORT TERM...AYD
LONG TERM/AVIATION...JV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
516 AM EST SUN MAR 3 2013
.SYNOPSIS...
STUBBORN UPPER LEVEL LOW CONTINUES TO BRING SNOW SHOWERS THROUGH
TONIGHT. HIGH PRESSURE CROSSES MONDAY. ANOTHER LOW PRESSURE
SYSTEM CROSSES TUESDAY THROUGH WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
BROAD UPPER TROUGH CONTINUES TO SPIN OVER THE NORTHEAST CONUS...WITH
ANOTHER DISTURBANCE ROTATING AROUND ITS BACKSIDE FROM NW TO SE TODAY.
12Z THIS MORNING AFOREMENTIONED UPPER LOW OVER NORTHEAST CENTERED
ROUGHLY OVER THE NYC AREA BUT WILL FINALLY BEGIN A SLOW EXODUS TO
THE EAST...PROGGED TO BE JUST SOUTH OF CAPE COD MASS BY 00Z SUN. AS
IT DOES SO...ONE FINAL S/W TROUGH WILL QUICKLY DROP SSE-WARD WITH
AXIS OVER WESTERN OHIO BY 18Z AND NEAR THE OHIO RIVER BY 00Z SUN.
LATEST NAM 03.00 RUN IN FACT ATTEMPTS TO BRIEFLY CLOSE THIS 500MB
LOW OFF BY THIS TIME. LARGE SCALE ASCENT PUSHES INTO THE WESTERN
ZONES BY 12Z AND IS MAXIMIZED OVER THE SOUTHERN ZONES AROUND 18Z. IN
ADDITION...A DECENT AREA OF POTENTIAL VORT ADVECTION PUSHES ACROSS
THE AREA AS WELL BTWN 18Z SAT AND 00Z SUN. AS WITH
YESTERDAY...AMOUNT OF LLVL MOISTURE IS SOMEWHAT IN QUESTION PER NAM
SOUNDINGS. RUC SOUNDINGS HOWEVER INDICATE A DEEPER SATURATED LLVL AS
IT DID YESTERDAY. WITH THIS IN MIND...EXPECT A DAY FAIRLY SIMILAR TO
YESTERDAY WITH OFF/ON FLURRIES AND SNOW SHOWERS. AS SUCH...WILL KEEP
AT LEAST SLIGHT CHANCE POPS GOING FOR THE AREA FOR MUCH OF THE
DAY...WITH THE USUAL HIGHER CHANCE POPS IN THE EASTERN HIGH COUNTRY.
ALSO LOWERED MAX TEMPS A BIT. DEPENDING ON MODEL OF CHOICE...925MB
TEMPS IDENTICAL OR A BIT COOLER THIS AFTERNOON VERSUS YESTERDAY AND
WITH THE EXPECTED CLOUD COVER AND FLURRIES AND/OR LIGHT SNOW
AROUND...TEMPS SHOULD BE ABOUT IDENTICAL TO YESTERDAY/S READINGS.
BY 00Z SUN TROUGH AXIS/POSSIBLE CUT OFF LOW NEAR THE OHIO RIVER WITH
THE LARGE SCALE FORCING FOR ASCENT EAST OF IT BUT EXITING THE
AREA...WHICH SHOULD EFFECTIVELY END PRECIP CHANCES FOR LOWLAND
LOCATIONS. TRAPPED LLVL MOISTURE IN THE USUAL FAVORED UPSLOPE AREAS
OF THE NORTHEAST MOUNTAINS SHOULD SEE AN INCREASE IN SNOWFALL
ACTIVITY DURING THE EVENING HOURS AS TROUGH WITH ASSOC LIFT MAKES
ITS WAY THROUGH. 850MB WIND TRAJECTORY OFF LAKE ERIE NOT THE BEST
BUT PRESENT NONETHELESS OFF THE WESTERN TIP. ANTICIPATE A GENERAL
INCH TO TWO INCHES FOR THIS AREA WITH LESSER AMOUNTS IN THE
VALLEYS...WITH THE SNOWFALL TAPERING OFF BY THE END OF THE PERIOD.
ACROSS THE LOWLANDS CLOUDS INTO THE OVERNIGHT HOURS WILL GIVE WAY TO
SOME PARTIAL CLEARING IN THE LATE HOURS TOWARDS DAWN. GIVEN THE
RELATIVELY LOW MAX TEMPS TODAY WITH LIGHT WINDS AND DEWPTS INTO THE
UPPER TEENS...LOWLAND MINS SHOULD HAVE NO TROUBLE FALLING TO AROUND
THE 20 DEGREE MARK BY DAWN MONDAY.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
HIGH PRESSURE PROVIDES WEAK PRESSURE GRADIENT AND WEAK OR CALM
FLOW MONDAY AND MONDAY NIGHT. DRY AND COLDER AIR ALOFT UNDER
NORTHWEST FLOW WILL PROVIDE SUBSIDENCE AND DRY WEATHER...AND
PROBABLY MOSTLY CLEAR SKIES THROUGH MONDAY EVENING.
HIGH LEVEL CLOUDS WILL INCREASE LATER MONDAY NIGHT...AHEAD OF A
SOUTHERN STREAM LOW PRESSURE SYSTEM. DIFFERENCES ARE NOTICEABLE
AMONG SYNOPTIC MODELS...WITH THE LOW CENTER LOCATION AND TRAJECTORY
BY 12Z TUESDAY...FROM EXTREME SOUTHWEST KY TO CENTRAL OH.
THEREFORE...CONFIDENCE IS LOW AT THIS TIME.
DESPITE OF DIFFERENT TRAJECTORY SOLUTIONS...ALL MODELS INJECT
WARM AND MOIST AIR ADVECTION UNDER SOUTHWESTERLY FLOW ON TUESDAY...TO
PRODUCE LIQUID PCPN AHEAD AND ALONG A WARM FRONT PASSAGE. ALL
MODELS ARE IN AGREEMENT WITH A WARM NOSE FROM H850 TO H900
SUGGESTING LIQUID PCPN ON TUESDAY. HOWEVER...AS THE LOW CONTINUES
ITS EAST NORTHEAST TRAJECTORY...WRAP AROUND COLDER AIR WILL BRING
THE MINUS 5C TEMPERATURE LINE ACROSS THE OUR CWA DURING THE
PREDAWN HOURS WEDNESDAY MORNING. THE NAM IS THE FASTER WITH THIS
FEATURE OVERHEAD BY 03Z WEDNESDAY. IT STILL UNCERTAIN WHETHER A
DRY SLOT WILL REDUCE PCPN BEHIND THE RAIN BATCH ASSOCIATED WITH
THE WARM FRONT...BEFORE THE REAL COLDER AIR MOVES IN AND CHANGES
WINTRY PCPN FROM MIX TO ALL SNOW BY WEDNESDAY MORNING 12-15Z.
HPC WWD SNOW ACCUMULATIONS GUIDANCE LOOKS TOO GENEROUS WITH 8-10
INCHES OF SNOW ACROSS NORTHEAST MOUNTAINS ENDING BY 12Z WEDNESDAY.
NOT EVEN THE SREF SUPPORT THIS PCPN TYPE CHANGING TO ALL SNOW BY
THIS TIME. BELIEVE...THE RAIN TO SNOW TRANSITION WILL OCCUR EARLY
WEDNESDAY MORNING...AND THE HEAVIEST SNOW AMOUNTS THROUGH THE
AFTERNOON AND EVENING HOURS. THEREFORE...KEPT MENTIONED OF
SIGNIFICANT HEAVY WET SNOW IN HWO AND SYN PRODUCTS FROM PREVIOUS
FORECAST PACKAGE.
A BLEND BETWEEN MAV AND MET GUIDANCE RESEMBLES PREVIOUS
TEMPERATURES THROUGH THE PERIOD. THEREFORE...MADE MINOR TWEAKS
HERE AND THERE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE MARCH LION WILL BE ROAMING OUR AREA EARLY IN THE EXTENDED. THE
AMERICAN MODELS CONTINUE TO BE A BIT FASTER WITH THE CLOSED 500 MB
LOW MOVING EAST...OUT OF THE MID MISSISSIPPI VALLEY OR LOWER OHIO
VALLEY ON TUESDAY EVENING...COMPARED TO THE ECMWF. BUT THE 12Z
ECMWF SEEMS TO BE CATCHING UP.
ALL THE MODELS CONTINUE TO AGREE...THE 500 MB LOW PASSES TO OUR
SOUTH...PROBABLY OVER THE SMOKY MOUNTAINS AROUND 12 WEDNESDAY...
THEN NEAR THE NC OUTER BANKS AT 00Z THURSDAY. PICTURING THIS SYSTEM
TO BE STRONG ENOUGH TO BACK THE 700 MB FLOW AND THROW THE DEEPER
MOISTURE W/NW AS THE COLUMN COOLS LATE TUESDAY NIGHT AND EARLY
WEDNESDAY MORNING. AS A RESULT...FORECASTING THE POSSIBILITY OF
HEAVY WET SNOW OVER THE MOUNTAINOUS COUNTIES...ESPECIALLY WV
MOUNTAIN COUNTIES. HAVE INTRODUCED A HAZARD IN OUR HAZARDOUS
WEATHER POTENTIAL...FOR HEAVY WET SNOW...WATCH/WARNING STUFF FOR THE
WV MOUNTAIN COUNTIES...INCLUDING THE BKW/EKN VCNTY. EVEN...THE
LOWLAND COUNTIES COULD HAVE SOME LESSER ACCUMULATIONS WITH SOME
ADVISORIES.
WILL LEAVE HIGHER POPS LONGER THAN GUIDANCE AND PREVIOUS FORECAST
FOR WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING...BUT A STRONG POP
GRADIENT OVER THE OHIO VALLEY COUNTIES.
THE MARCH ENVIRONMENT FINALLY SETTLES DOWN FOR THURSDAY INTO
SATURDAY. A WEAK FEATURE MAY SAG DOWN FROM THE NORTH ON SATURDAY
AFTERNOON AND NIGHT.
&&
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
PREDOMINANTLY MVFR CIGS PREVAIL IN THE CONTINUED W TO NW FLOW OF
COLD AIR...WITH OCCASIONAL LOW VFR CIGS OVERNIGHT. IFR CIGS
EXPECTED TO BECOME MORE PREVALENT LATE OVERNIGHT THROUGH DAWN
SUNDAY. VSBY RESTRICTIONS IN SCATTERED SNOW SHOWERS WILL TEND TO
BECOME MORE CONFINED TO THE MOUNTAINS OVERNIGHT WITH MVFR
INTERSPERSED WITH BRIEF IFR IN A HEAVIER SNOW SHOWER.
SUNDAY WILL BRING MODEST IMPROVEMENT WITH STRATOCU CIGS GETTING TO
VFR BY AFTERNOON FOR LOWLAND LOCATIONS...WITH EASTERN MOUNTAIN
LOCATIONS REMAINING MVFR. EXPECT SNOW SHOWERS IN THE MOUNTAINS TO
WIND DOWN SOMEWHAT BY MIDDAY BUT PICK UP ONCE AGAIN BY AND AFTER
00Z MON.
LIGHT W TO NW SFC FLOW WITH LIGHT TO MODERATE NW FLOW ALOFT CONTINUES
THROUGH THE PERIOD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: TIMING OF SNOW AND ASSOCIATED RESTRICTIONS MAY
VARY. TIMING OF CEILING CATEGORY CHANGES MAY ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 03/03/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY H H H H M H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY M M M M M M L L M H H H
EKN CONSISTENCY M M M L L L L L L L L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY L L L L L L L L L L H H
AFTER 12Z MONDAY...
IFR VISIBILITIES AND CEILINGS POSSIBLE IN RAIN/SNOW TUESDAY THROUGH
WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...50
SHORT TERM...ARJ
LONG TERM...KTB
AVIATION...50
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
420 AM EST SUN MAR 3 2013
.SYNOPSIS...
STUBBORN UPPER LEVEL LOW CONTINUES TO BRING UPSLOPE SNOW SHOWERS
INTO SUNDAY. HIGH PRESSURE CROSSES MONDAY. ANOTHER LOW PRESSURE
SYSTEM CROSSES TUESDAY THROUGH WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
BROAD UPPER TROUGH CONTINUES TO SPIN OVER THE NORTHEAST CONUS...WITH
ANOTHER DISTURBANCE ROTATING AROUND ITS BACKSIDE FROM NW TO SE TODAY.
12Z THIS MORNING AFOREMENTIONED UPPER LOW OVER NORTHEAST CENTERED
ROUGHLY OVER THE NYC AREA BUT WILL FINALLY BEGIN A SLOW EXODUS TO
THE EAST...PROGGED TO BE JUST SOUTH OF CAPE COD MASS BY 00Z SUN. AS
IT DOES SO...ONE FINAL S/W TROUGH WILL QUICKLY DROP SSE-WARD WITH
AXIS OVER WESTERN OHIO BY 18Z AND NEAR THE OHIO RIVER BY 00Z SUN.
LATEST NAM 03.00 RUN IN FACT ATTEMPTS TO BRIEFLY CLOSE THIS 500MB
LOW OFF BY THIS TIME. LARGE SCALE ASCENT PUSHES INTO THE WESTERN
ZONES BY 12Z AND IS MAXIMIZED OVER THE SOUTHERN ZONES AROUND 18Z. IN
ADDITION...A DECENT AREA OF POTENTIAL VORT ADVECTION PUSHES ACROSS
THE AREA AS WELL BTWN 18Z SAT AND 00Z SUN. AS WITH
YESTERDAY...AMOUNT OF LLVL MOISTURE IS SOMEWHAT IN QUESTION PER NAM
SOUNDINGS. RUC SOUNDINGS HOWEVER INDICATE A DEEPER SATURATED LLVL AS
IT DID YESTERDAY. WITH THIS IN MIND...EXPECT A DAY FAIRLY SIMILAR TO
YESTERDAY WITH OFF/ON FLURRIES AND SNOW SHOWERS. AS SUCH...WILL KEEP
AT LEAST SLIGHT CHANCE POPS GOING FOR THE AREA FOR MUCH OF THE
DAY...WITH THE USUAL HIGHER CHANCE POPS IN THE EASTERN HIGH COUNTRY.
ALSO LOWERED MAX TEMPS A BIT. DEPENDING ON MODEL OF CHOICE...925MB
TEMPS IDENTICAL OR A BIT COOLER THIS AFTERNOON VERSUS YESTERDAY AND
WITH THE EXPECTED CLOUD COVER AND FLURRIES AND/OR LIGHT SNOW
AROUND...TEMPS SHOULD BE ABOUT IDENTICAL TO YESTERDAY/S READINGS.
BY 00Z SUN TROUGH AXIS/POSSIBLE CUT OFF LOW NEAR THE OHIO RIVER WITH
THE LARGE SCALE FORCING FOR ASCENT EAST OF IT BUT EXITING THE
AREA...WHICH SHOULD EFFECTIVELY END PRECIP CHANCES FOR LOWLAND
LOCATIONS. TRAPPED LLVL MOISTURE IN THE USUAL FAVORED UPSLOPE AREAS
OF THE NORTHEAST MOUNTAINS SHOULD SEE AN INCREASE IN SNOWFALL
ACTIVITY DURING THE EVENING HOURS AS TROUGH WITH ASSOC LIFT MAKES
ITS WAY THROUGH. 850MB WIND TRAJECTORY OFF LAKE ERIE NOT THE BEST
BUT PRESENT NONETHELESS OFF THE WESTERN TIP. ANTICIPATE A GENERAL
INCH TO TWO INCHES FOR THIS AREA WITH LESSER AMOUNTS IN THE
VALLEYS...WITH THE SNOWFALL TAPERING OFF BY THE END OF THE PERIOD.
ACROSS THE LOWLANDS CLOUDS INTO THE OVERNIGHT HOURS WILL GIVE WAY TO
SOME PARTIAL CLEARING IN THE LATE HOURS TOWARDS DAWN. GIVEN THE
RELATIVELY LOW MAX TEMPS TODAY WITH LIGHT WINDS AND DEWPTS INTO THE
UPPER TEENS...LOWLAND MINS SHOULD HAVE NO TROUBLE FALLING TO AROUND
THE 20 DEGREE MARK BY DAWN MONDAY.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
COULD STILL BE A FEW LINGERING UPSLOPE SNOW SHOWERS OR FLURRIES
ACROSS MOUNTAIN ZONES LATE SUNDAY NIGHT...BUT FOR THE MOST
PART...ANY LINGERING PRECIPITATION WILL TAPER OFF AS ATMOSPHERE
CONTINUES TO DRY OUT AS SURFACE HIGH BUILDS INTO THE REGION
TEMPORARILY. AS IT DOES SO...WILL SEE A GRADUAL CLEARING OF SKY
COVER SUNDAY NIGHT INTO EARLY MONDAY...AND WITH THE SURFACE HIGH
OVERHEAD...WILL SEE A NIGHT OF GOOD RADIATIONAL COOLING...DEPENDING
ON THE AMOUNT OF CLEARING THAT IS ABLE TO TAKE PLACE. WITH 850MB
TEMPS SUNDAY NIGHT/EARLY MONDAY DIPPING TO AROUND -13C...EXPECT MANY
MOUNTAINOUS LOCATIONS TO DIP INTO THE SINGLE DIGITS TO LOWER
TEENS...WITH TEENS TO LOWER 20S ACROSS THE LOWLANDS.
SHORTWAVE RIDGING WILL THEN GRADUALLY BUILD ACROSS THE AREA FOR
MONDAY INTO TUESDAY OUT AHEAD OF THE NEXT LOW PRESSURE
SYSTEM...WHICH WILL PUSH A WARM FRONTAL BOUNDARY INTO THE CWA IN THE
MONDAY NIGHT THROUGH TUESDAY TIME FRAME. EXPECT A GRADUAL WARM UP IN
TEMPERATURES AS COMPARED TO RECENT DAYS ON MONDAY AND TUESDAY...WITH
PRECIPITATION GRADUALLY SPREADING INTO THE CWA BY EARLY TUESDAY.
DEPENDING ON THE TIMING AND EXACT TRACK OF THE LOW...COULD SEE
PRECIPITATION START OFF AS A WINTRY MIX ACROSS LOWLANDS...BEFORE
CHANGING TO RAIN AS THE DAY PROGRESSES. HIGHER ELEVATIONS WILL STAY
PREDOMINATELY SNOW OR A MIX THROUGHOUT THE DAY. IN ADDITION...MODELS
INDICATING SOME WEAK INSTABILITY ACROSS EXTREME SOUTHERN ZONES...AND
AS A RESULT...ELECTED TO ADD IN A SLIGHT CHANCE OF THUNDER INTO THE
FORECAST FOR TUESDAY AFTERNOON...MAINLY IN SW VA ZONES. STILL A FEW
ISSUES WITH TIMING AND EXACT TRACK WITH THIS SYSTEM HOWEVER...AS IS
TO BE EXPECTED. THEREFORE...STILL A BIT OF AN ISSUE CONCERNING
PRECIPITATION TYPE EARLY IN THE PERIOD...COULD BE EITHER RAIN OR
SNOW...OR EVEN SLEET AT TIMES. FOR NOW...RAN JUST A RAIN/SNOW MIX OR
SNOW SCENARIO DUE TO THE UNCERTAINTY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE MARCH LION WILL BE ROAMING OUR AREA EARLY IN THE EXTENDED. THE
AMERICAN MODELS CONTINUE TO BE A BIT FASTER WITH THE CLOSED 500 MB
LOW MOVING EAST...OUT OF THE MID MISSISSIPPI VALLEY OR LOWER OHIO
VALLEY ON TUESDAY EVENING...COMPARED TO THE ECMWF. BUT THE 12Z
ECMWF SEEMS TO BE CATCHING UP.
ALL THE MODELS CONTINUE TO AGREE...THE 500 MB LOW PASSES TO OUR
SOUTH...PROBABLY OVER THE SMOKY MOUNTAINS AROUND 12 WEDNESDAY...
THEN NEAR THE NC OUTER BANKS AT 00Z THURSDAY. PICTURING THIS SYSTEM
TO BE STRONG ENOUGH TO BACK THE 700 MB FLOW AND THROW THE DEEPER
MOISTURE W/NW AS THE COLUMN COOLS LATE TUESDAY NIGHT AND EARLY
WEDNESDAY MORNING. AS A RESULT...FORECASTING THE POSSIBILITY OF
HEAVY WET SNOW OVER THE MOUNTAINOUS COUNTIES...ESPECIALLY WV
MOUNTAIN COUNTIES. HAVE INTRODUCED A HAZARD IN OUR HAZARDOUS
WEATHER POTENTIAL...FOR HEAVY WET SNOW...WATCH/WARNING STUFF FOR THE
WV MOUNTAIN COUNTIES...INCLUDING THE BKW/EKN VCNTY. EVEN...THE
LOWLAND COUNTIES COULD HAVE SOME LESSER ACCUMULATIONS WITH SOME
ADVISORIES.
WILL LEAVE HIGHER POPS LONGER THAN GUIDANCE AND PREVIOUS FORECAST
FOR WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING...BUT A STRONG POP
GRADIENT OVER THE OHIO VALLEY COUNTIES.
THE MARCH ENVIRONMENT FINALLY SETTLES DOWN FOR THURSDAY INTO
SATURDAY. A WEAK FEATURE MAY SAG DOWN FROM THE NORTH ON SATURDAY
AFTERNOON AND NIGHT.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
PREDOMINANTLY MVFR CIGS PREVAIL IN THE CONTINUED W TO NW FLOW OF
COLD AIR...WITH OCCASIONAL LOW VFR CIGS OVERNIGHT. IFR CIGS
EXPECTED TO BECOME MORE PREVALENT LATE OVERNIGHT THROUGH DAWN
SUNDAY. VSBY RESTRICTIONS IN SCATTERED SNOW SHOWERS WILL TEND TO
BECOME MORE CONFINED TO THE MOUNTAINS OVERNIGHT WITH MVFR
INTERSPERSED WITH BRIEF IFR IN A HEAVIER SNOW SHOWER.
SUNDAY WILL BRING MODEST IMPROVEMENT WITH STRATOCU CIGS GETTING TO
VFR BY AFTERNOON FOR LOWLAND LOCATIONS...WITH EASTERN MOUNTAIN
LOCATIONS REMAINING MVFR. EXPECT SNOW SHOWERS IN THE MOUNTAINS TO
WIND DOWN SOMEWHAT BY MIDDAY BUT PICK UP ONCE AGAIN BY AND AFTER
00Z MON.
LIGHT W TO NW SFC FLOW WITH LIGHT TO MODERATE NW FLOW ALOFT CONTINUES
THROUGH THE PERIOD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: TIMING OF SNOW AND ASSOCIATED RESTRICTIONS MAY
VARY. TIMING OF CEILING CATEGORY CHANGES MAY ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 03/03/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY H H H H M H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY M M M M M M L L M H H H
EKN CONSISTENCY M M M L L L L L L L L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY L L L L L L L L L L H H
AFTER 06Z MONDAY...
IFR VISIBILITIES AND CEILINGS POSSIBLE IN RAIN/SNOW TUESDAY THROUGH
WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...50
SHORT TERM...ARJ
LONG TERM...KTB
AVIATION...50
AREA FORECAST DISCUSSION
NWS PORTLAND OR
910 PM PST SAT MAR 2 2013
.SYNOPSIS...A SHARP COLD FRONT HAS MOVED ACROSS THE INTERSTATE 5
CORRIDOR AND IS NOW MOVING INTO THE CASCADES THIS EVENING. THIS FRONT
IS PRODUCING SOME RAIN...BUT THE MORE NOTABLE EFFECT IS A SHARP DROP
IN TEMPERATURE AND LOWERING SNOW LEVELS. SHOWERS WILL DECREASE LATER
TONIGHT AND EARLY SUNDAY...WITH JUST SOME ISOLATED SHOWERS IN THE
HIGHER TERRAIN BY SUNDAY AFTERNOON. OTHERWISE MOST AREAS WILL BEGIN
TO DRY OUT AS COOL HIGH PRESSURE BUILDS IN FOR SUNDAY NIGHT AND
MONDAY. BROAD LOW PRESSURE FROM THE GULF OF ALASKA IS EXPECTED TO CUT
OFF FROM THE MAIN FLOW AND LINGER NEAR THE OREGON COAST...RESULTING
IN UNSETTLED WEATHER FOR THE MIDWEEK PERIOD.
&&
.SHORT TERM...TODAY THROUGH TUESDAY...A SHARP COLD FRONT BY WEST
COAST STANDARDS IS MOVING ACROSS THE WASHINGTON AND OREGON THIS
EVENING. AS THE FRONT MOVED THROUGH THE PORTLAND METRO IT WAS
ACCOMPANIED BY THE TEXTBOOK SHARP WIND SHIFT FROM SOUTH AHEAD OF THE
FRONT TO NORTHWEST BEHIND THE FRONT. TEMPS/DEWPOINTS TUMBLED ABOUT 5
DEGREES ALMOST IMMEDIATELY WITH THE PASSAGE OF THE FRONT. ANYWHERE
EAST OF THE ROCKIES THIS WOULD NOT BE CONSIDERED TOO SIGNIFICANT...
BUT HERE ON THE WEST COAST IT IS NOT TOO COMMON TO SEE THIS TYPE OF
TEXTBOOK COLD FRONT. THE FREEZING LEVEL HAS FALLEN FROM 9000 FT THIS
MORNING TO 2000-3000 FT BEHIND THE FRONT...ABERNATHY MTN RAWS AT 2000
FT ELEVATION IN NW COWLITZ COUNTY WAS 33 DEGREES AS OF 8 PM. IT IS
LIKELY SNOW IS BEGINNING TO MIX WITH RAIN IN SCATTERED SHOWERS ABOVE
1500-2000 FT IN THE COAST RANGE.
WHAT THE COLD FRONT HAD IN TEMPERATURE AND DEWPOINT GRADIENT...IT DID
NOT HAVE IN IMPRESSIVE MOISTURE. THE UPPER DYNAMICS ASSOCIATED WITH
THIS SYSTEM WERE QUITE DISORGANIZED AS THE FRONT CAME IN. BASICALLY
THE FRONT ONLY HAD SURFACE MOISTURE AND LIFT TO WORK WITH...SO MOST
LOCATIONS STRUGGLED TO PICK UP MORE THAN 0.10 INCH. SOME SPOTS IN THE
EAST METRO...INCLUDING OUR OFFICE IN PARKROSE... HAD A LITTLE MORE
WITH A QUICK 0.20 INCH IN THE BUCKET SINCE 4 PM. WITH SHOWERS
DECREASING QUICKLY IN THE COLDER AIR IT APPEARS ANY SNOW
ACCUMULATIONS ABOVE 1500-2000 FT SHOULD BE LIGHT AND SPOTTY. THE BEST
CHANCE FOR A COUPLE INCHES WILL BE ABOVE 3000 FT.
UPPER DYNAMICS ARE ALREADY STARTING TO FOCUS EAST OF THE CASCADES AS
AN UPPER LOW PUSHES SOUTHEAST FROM BRITISH COLUMBIA INTO THE ROCKIES.
MEANWHILE LATEST RAP ANALYSIS SHOWS 700 MB TEMPS ALREADY WARMING WEST
OF 127-128W...CAPPING OFF ANY WEAK INSTABILITY OFFSHORE. IT IS QUITE
LIKELY SHOWERS WILL END FOR MOST BY SUNRISE SUNDAY...WITH THE BEST
CHANCE FOR LINGERING CLOUDS AND SHOWERS IN THE NORTH AND IN THE
HIGHER TERRAIN OF OUR FORECAST AREA.
HIGH PRESSURE BUILDS IN LATER SUNDAY FOR A MAINLY CLEAR AND CHILLY
NIGHT. THE EXCEPTION WILL BE SOME PATCHY VALLEY FOG IN THE TYPICAL
FOG PRONE AREAS. TEMPERATURES MAY FALL BELOW FREEZING IN MOST
OUTLYING VALLEYS...POSSIBLY FLIRTING WITH 32F EVEN AT KPDX. OFFSHORE
FLOW LIKELY MAKES MONDAY A MOSTLY SUNNY AND SEASONABLE DAY.
AN UPPER LOW CURRENTLY TRAVERSING THE ALEUTIANS IS PROGGED TO MOVE
ACROSS THE GULF OF ALASKA AND SETTLE AS A CUTOFF LOW SOMEWHERE OFF
THE OREGON OR NORTHERN CALIFORNIA COAST MONDAY NIGHT AND TUESDAY. AS
WITH MOST CUTOFF LOWS THERE IS A LOT OF UNCERTAINTY IN THE PACE AND
TRACK OF THIS SYSTEM AND ITS ASSOCIATED FRONT. 00Z NAM CONTINUES TO
BE THE FASTEST MODEL SPREADING RAIN ONSHORE MON NIGHT...WHILE THE
GFS/ECMWF/GEM CONSENSUS IS ABOUT 6-12 HOURS SLOWER. DEPENDING ON THE
TIMING...THERE IS AN OUTSIDE CHANCE OF SOME SNOW/ICE ISSUES IN THE
HOOD RIVER VALLEY DUE TO COLD AIR LEFT BEHIND BY OUR CURRENT SYSTEM.
THE LAST COUPLE NAM BUFR SOUNDINGS HAVE SUGGESTED SNOW AT LEAST FOR
THE UPPER HOOD RIVER VALLEY TUE MORNING. WILL NEED TO WATCH THIS...
OTHERWISE JUST EXPECT AN INCREASING CHANCE OF RAIN AND MOUNTAIN SNOW
TUESDAY. WEAGLE
.LONG TERM...TUESDAY EVENING THROUGH SATURDAY...AN UPPER LEVEL
CLOSED LOW IS PROGGED TO APPROACH THE OR COAST ON TUE...PUSHING AN
OCCLUDED FRONT THROUGH THE REGION DURING THE DAY TUE. EXPECT STEADY
RAIN WITH THE FRONT...THEN A TRANSITION TO SHOWERY WEATHER TUE NIGHT
AND WED AS THE LOW PUSHES SLOWLY INLAND. THE ATMOSPHERE WILL BE
FAIRLY UNSTABLE...AND A COLD AIRMASS ASSOCIATED WITH THE LOW MAY
ALLOW HEAVIER SHOWERS TO FALL AS SNOW DOWN INTO THE FOOTHILLS AND
COAST RANGE...BUT LITTLE SIGNIFICANT IMPACT IS EXPECTED. DUE TO THE
INSTABILITY WE DECIDED TO ADD A SLIGHT CHANCE OF THUNDER TO THE COAST
AND ADJACENT WATERS TUE AFTERNOON THRU WEDNESDAY. SHOWER
ACTIVITY SHOULD TAPER OFF WED NIGHT INTO THU AS THE LOW PUSHES EAST
INTO THE GREAT BASIN. DRIER WEATHER IS EXPECTED TO DEVELOP FOR THE
END OF THE WEEK AND INTO THE WEEKEND AS A PERIOD OF SHORTWAVE
RIDGING BUILDS INTO THE PAC NW. PYLE/BROWN/WEAGLE
&&
.AVIATION...COLD FRONT HAS CLEARED THE NORTH INTERIOR AND PUSHED
INTO THE CASCADES. THE FRONT SLOPES BACK TO THE SOUTHWEST...THUS
IT SHOULD BE ENTERING THE SOUTH VALLEY SOON. MOSTLY VFR CONDITIONS
EXIST WITH A FEW POCKETS OF MVFR. EXPECT CLOUDS TO BREAK UP SOME
OVERNIGHT. SEEMS REASONABLE THAT STRATUS OR FOG IS
POSSIBLE...THOUGH FEEL MVFR STRATUS HAS A BETTER CHANCE GIVEN THE
POST FRONTAL UNSTABLE AIR MASS. NOT MUCH IN THE WAY OF SHOWER
ACTIVITY OFFSHORE...THOUGH CANNOT RULE OUT A FEW FOR THE NORTHERN
TIER. ANY LOW CLOUD THAT FORMS DOES NOT LOOK LIKE IT WILL LAST
BEYOND THE MORNING.
KPDX AND APPROACHES...VFR CONDITIONS HAVE RETURNED TO THE
TERMINAL...WITH THE BULK OF THE PRECIPITATION CONFINED TO EAST
APPROACHES. WITH CLEARING SKIES OVERNIGHT AND WINDS EASING...HAVE
THE POTENTIAL OF FORMING STRATUS AFTER 10Z. CURRENT GUIDANCE
SUGGESTS MVFR...TOUGH TO SAY HOW LOW AT THIS POINT. ROCKEY/KMD
&&
.MARINE...COLD FRONT HAS PUSHED ONSHORE. STRONGEST GRADIENT LIES
ALONG THE NORTHERN WATERS THIS EVENING...THUS W TO NW WINDS
GUSTING AROUND 25 KT EASING TOWARDS MIDNIGHT. SEAS NOT CHANGING
MUCH...GENERALLY 9 TO 11 FT. ENP GUIDANCE IS RUNNING A TOUCH
HIGH.
HIGH PRESSURE BUILDS IN SUNDAY...AND PUSHES INLAND SUN NIGHT. THIS
WILL ALLOW OFFSHORE FLOW TO DEVELOP AHEAD OF THE NEXT SYSTEM
DROPPING SOUTH FROM THE GULF OF ALASKA EARLY IN THE WEEK. AS IT
APPROACHES...EXPECT SEAS TO RISE BACK INTO THE LOWER TEENS LATE
MONDAY OR EARLY TUESDAY...WHILE WIND GUSTS MAY APPROACH NEAR GALE
FORCE LATER MON INTO MON EVENING. THE LOW THEN MOVES OVER THE
WATERS RESULTING IN LIGHTER WINDS...THOUGH A SHOWERY AND UNSTABLE
AIRMASS WILL RESULT IN ERRATIC GUSTY WINDS AT TIMES. KMD
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL MIDNIGHT PST TONIGHT FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR
OUT 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM PST SUNDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 7 AM PST
SUNDAY.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 5 PM TO
11 PM PST SUNDAY.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
355 PM EST SUN MAR 3 2013
.SYNOPSIS...
A SLOW MOVING UPPER LOW OVER THE NORTHEASTERN STATES WILL EXIT OFF
THE NEW ENGLAND COAST BY LATE MONDAY ALLOWING WEAK HIGH PRESSURE
TO BUILD ACROSS THE LOCAL AREA. LOW PRESSURE WILL DEVELOP IN THE
HIGH PLAINS SUNDAY AND MONDAY AND TAKE A TRACK THROUGH THE OHIO
VALLEY AND MID-ATLANTIC STATES TUESDAY NIGHT AND WEDNESDAY. THIS
STORM WILL PROBABLY PASS TO THE SOUTH OF THE STATE...BUT WILL MOST
LIKELY BRING SNOW INTO SOUTHERN PENNSYLVANIA IN THE MIDDLE OF THE
WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
FORECAST STRONGLY CONTINUOUS...AND FLURRIES OR LIGHT SNOW EXPECTED
FOR THE ENTIRE NIGHT. RECENT HRRR AND RUC/RAP HAVE BEEN INDICATING
THAT WE COULD GET SOME ENHANCED LLVL OMEGA THIS EVENING AS AN
UPPER LEVEL LOW FILLS AND PASSES N-S THRU OH. WILL KEEP POPS HIGH
THEN PLAY A GRADUAL DECREASE IN POPS/SNOW INTENSITY AND AMOUNTS
AFTER MIDNIGHT. BUT THE FLOW DOES NOT CHANGE DIRECTION AND THE
PRES GRADIENT STAYS TIGHT. SHOULD BE BREEZY WITH 10MPH+ WINDS ALL
NIGHT. THE FLUFFINESS OF THE SNOW IN THIS DRY AIR MASS AND COLD
CLOUD TEMPS RESULTED IN SLR/S IN THE 30:1 RANGE SUN MORNING.
THEREFORE...ACCUMS OF A DUSTING TO AN INCH PROBABLE OVER THE NWRN
HALF OF THE AREA...WITH 1-3 IN THE FAR NRN TIER AND IN THE
LAURELS. TEMPS ALREADY BELOW NORMALS...BUT CLOUD COVER WILL HELP
TO KEEP THEM GOING TOO FAR BELOW NORMAL MINS BY MON MORNING.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
SFC HIGH PRESSURE RIDGE TO THE WEST INCHES CLOSER AND 5H HEIGHTS
RISE GREATLY OVER THE GREAT LAKES AND OH VALLEY AND SOMEWHAT HERE
AS WELL. LLVL PRES GRADIENT STAYS TIGHT DURING THE DAY AND MIXING
DEEPER THAN SUNDAY SHOULD ENHANCE THE WINDS IN THE AFTN. THE CLOUD
DECK WILL BECOME MORE-DIFFUSE THROUGH THE MORNING AND CLEARING
POSSIBLE ACROSS THE SOUTH AND EAST-CENTRAL COS IN THE AFTN. NW
FLOW STILL DOMINATES MUCH OF THE DAY...BUT RELAXES AND BECOMES
SLIGHTLY ANTI-CYCLONIC LATER IN THE DAY. THIS ALSO POINTS TO A
SUBSIDENCE OF THE SHSN...BUT THEY WILL LIKELY HOLD ON LONGEST IN
THE NRN TIER. CLOUDS WILL LINGER EVEN LONGER...PERHAPS STAYING
NEAR 100PCT THRU THE EVENING HRS. WILL CONTINUE TO MENTION LIGHT
ACCUMS AND LIKELY POPS IN THE MTNS IN THE MORNING...BUT TAPER THEM
OFF LATER. DUE TO THE POSSIBILITY OF SUN IN THE SRN TIER AND ESP
THE SE...TEMPS SHOULD GET A LITTLE MILDER - BUT STILL BELOW NORMAL
ON MONDAY AFTN.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
REX BLOCK FROM THE CANADIAN MARITIMES SOUTH TO THE NEW ENGLAND COAST
WILL TEMPORARILY BREAK DOWN AS A VIGOROUS CHUNK OF UPPER ENERGY
DIVES SOUTHEAST ACROSS THE ROCKIES AND CARVES OUT A POTENT UPPER LOW
CENTER...WHICH TRACKS EAST FROM THE MID MISS VALLEY TO THE MID
ATLANTIC COAST BY LATE WEDNESDAY NIGHT.
FOR MONDAY NIGHT AND TUESDAY...THE PERSISTENT/COLD NWRLY FLOW WILL
RELAX AND AT LEAST PARTIAL CLEARING WILL OCCUR AS A RIDGE OF HIGH
PRESSURE AT THE SFC AND ALOFT SLIDES EAST ACROSS THE COMMONWEALTH.
U.S. MODELS AND ENSEMBLES HOPEFULLY CAN HANDLE THE UPCOMING CRITICAL
/HOME COURT/ WEATHER FOR THE MID-WEEK PERIOD BETTER THAN THE
ADMIRABLE RECORD OF THE /VISITING TEAM/ MODELS.../EC AND UKMET/.
THE 00Z THROUGH 12Z SREF AND GEFS...ALONG WITH THE OPERATIONAL
NAM/GFS AND UKMET HAVE BEEN IN FAIRLY GOOD AGREEMENT AND CLUSTERED
FURTHER NORTH WITH THE SFC/UPR LOW TRACK AND RESULTANT NORTHERN EDGE
OF THE SHIELD OF HEAVY SNOW...COMPARED TO THE EC/UKMET WHICH BARELY
BRUSHES EXTREME SOUTHERN PA AND THE LAURELS WITH A FEW TO SVRL
INCHES OF SNOW LATE TUESDAY THROUGH WEDNESDAY.
THE FOCUS FOR OUR WEATHER...AND SOMEWHAT HIGH DEGREE OF CONFIDENCE
FOR THE SOUTHERN 1-2 LAYERS OF COUNTIES GETTING INTO THE NORTHERN
EDGE OF MDT TO HVY SNOW ACTION...RESTS ON THE VERIFICATION/PLACEMENT
OF THE CONSISTENT AND HIGHLY ANOMALOUS /-3 TO -4 SIGMA/ EASTERLY
925-850 MB FLOW THAT/S BEEN CONSISTENTLY SHOWN AND AIMED INTO
SOUTHERN PENN AND POINTS SOUTH THE PAST FEW ENSEMBLE AND U.S.
OPERATIONAL MODEL RUNS.
THE PASSAGE OF THE LEFT EXIT REGION OF A HIGHLY CYCLONIC AND STRONG
120+ KT 300 MB JET...AND ASSOCIATED/PERSISTENT 850-700 MB FGEN
FORCING ACROSS SRN PA SUPPORTS THE LIKELIHOOD OF AN EXTENDED...18-24
HR PERIOD OF ENHANCED SNOWFALL NEAR AND TO THE SOUTH OF ROUTE 22 IN
SCENT PENN.
ACROSS THE CENTRAL THIRD OF THE STATE...EXPECT LIGHTER SNOW OF A FEW
TO SEVERAL INCHES UP TO AROUND THE I-80 CORRIDOR.
THE LATEST ENSEMBLE GUIDANCE /06-12Z GEFS AND 03-15Z SREF/ CONTINUE
TO BE THE HIGH-END...NORTHERN OUTLIERS DISPLAYING A MEAN LIQUID
EQUIVALENT 24 HR QPF OF 0.5 OF AN INCH NEAR AND JUST TO THE SOUTH OF
I-80...WHILE EARLIER RUNS LEADING UP TO AND INCLUDING THE 12Z GEFS
DEPICTED THE 24 HR 1-INCH CONTOUR BRUSHING THE MASON DIXON LINE OF
SCENT AND SERN PA.
THE FRESH IN...15Z RUN OF THE SREF HAS TRENDED EVEN FARTHER NORTH
WITH THE MODERATE TO HEAVY QPF /AND POTENTIALLY VERY SNOWFALL/ AND
NOW PLACES THE 1 INCH QPF CONTOUR AS FAR NORTH AND WEST AS KUNV AND
KJST...EAST TO KLNS. THIS IS SUPPORTED BY A SLIGHT NORTHERN SHIFT
AND STRENGTHENING TO THE 850 EASTERLY JET...WHICH IS NOW SHOWN TO BE
A WHOPPING -5 TO -6 SIGMA ACROSS SERN PA AT 18Z WED. WON`T BUY INTO
THESE MUCH HIGHER AMOUNTS NORTH OF THE PENN TURNPIKE JUST YET...AND
WOULD RATHER TAKE THE MORE PRUDENT AND CONSERVATIVE ROUTE
CONSIDERING THE LARGE...AND PERSISTENT DISAGREEMENT BY THE 00Z-12Z
EURO MODELS WITH THEIR MORE SOUTHERN TRACK.
THE FEATURE THAT SEEMS TO BE ONE OF THE MOST CONSISTENT ON THE SREF
AND GEFS /SUPPORTING MODERATE TO HEAVY SNOW SPREADING ACROSS THE SRN
THIRD TO HALF OF PENN/ HAS BEEN THE TRACK OF THE 250 MB LOW CENTER
RIGHT OVER KCMH AND KMGW LATE TUESDAY NIGHT AND WED MORNING...WHICH
PLACES CENTRAL AND SOUTHERN PENN UNDER AN EXTREMELY DIFFLUENT UPPER
FLOW AND MAINTAINS A DEEP EAST TO NE FLOW LATE TUESDAY NIGHT THROUGH
MUCH OF WED.
THE MAIN CONCERN USING THE ENSEMBLE QPF MEAN /AND AMOUNTS TWD THE
NRN EDGE OF THE PRECIP SHIELD/ IS THE LIKELY CONTAMINATION/SKEWING
BY A FEW OF THE EXCESSIVELY HIGH END MEMBERS THAT SHOW OVER 2.0
INCHES OF LEQ FOR CENTRAL AND SOUTHERN PENN.
USING A /MEDIAN/ VALUE...OR MEAN BY REMOVING A FEW OF THE VERY HIGH
AND LOW END MEMBERS TRIMS SOME OF THE EXCESS FAT /SNOWFALL/ FROM THE
NRN EDGE. THIS IS NOT TO SAY THAT THESE FRINGE ENSEMBLE MEMBERS
DON/T PROVIDE VALUABLE INSIGHT INTO THE POTENTIAL MAGNITUDE OF THE
STORM. RATHER...ON THE WHOLE...THEY BROAD-BRUSH HIGHER AMOUNTS TOO
FAR TO THE NORTH.
THE LATEST HWOCTP INDICATES THE GENERAL EXPECTED SNOWFALL FROM NORTH
TO SOUTH ACROSS THE STATE...AND OUR GRIDDED STORM TOTAL SNOWFALL IS
CONSERVATIVELY PLACED A FAIR AMOUNT BELOW THE OPERATIONAL
GFS/NAM/SREF AND GEFS MEAN. INITIAL ESTIMATES OF STORM TOTAL
SNOWFALL VARY FROM JUST A FEW INCHES NEAR AND TO THE NE OF KIPT...TO
BETWEEN 8-11 INCHES ACROSS THE SOUTHERN TIER COUNTIES /WITH A
GENERAL 3-6 INCHES NEAR AND JUST TO THE SOUTH OF A SEG-KUNV-KFIG
LINE.
AGAIN...ALL EYES WILL BE ON THE TRENDS OF THE LATER RUNS...ESP THE
SOUTHERN OUTLIERS - EC AND UKMET.
A CHILLY AND RATHER GUSTY NORTHERLY FLOW WITH ISOLATED TO SCATTERED
MTN SNOW SHOWERS FOLLOWS FOR THURSDAY...BEFORE HEIGHTS RISE AND
DAYTIME TEMPS MODERATE TO NEAR NORMAL BY FRIDAY AND SATURDAY. A FAST
MOVING AND RELATIVELY FLAT/WEAK NRN STREAM SHORTWAVE WILL TRACK
ACROSS THE GREAT LAKES AND NRN PENN SATURDAY INTO SATURDAY
NIGHT...POSSIBLY ACCOMPANIED BY A FEW SHOWERS OF RAIN AND WET SNOW
UP NORTH. SOUTHERN PORTIONS OF PENN SHOULD STAY MAINLY DRY THROUGH
THE WEEKEND...AFTER THE POTENTIAL HIGH IMPACT/HEAVY SNOW EVENT OF
LATE TUESDAY INTO EARLY THURSDAY.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
PERSISTENCE FORECAST REMAINS THE PHRASE FOR THE FCST PERIOD.
CLIMO NW FLOW PATTERN YIELDS GENERALLY MVFR/IFR CIGS IN THE
BFD/JST AND MVFR IN AOO/UNV. DRYING ON DOWNSLOPE IMPROVES
CONDITIONS EVEN MORE IN IPT/MDT/LNS. PRES GRADIENT KEEPING WINDS
IN THE 10-15KT RANGE WITH OCCASIONAL GUSTS INTO THE 20S ALMOST
EVERYWHERE. THE GRADIENT DOES NOT SLACKEN THROUGH THE NIGHT NOR ON
MONDAY. WILL KEEP WINDS PERSISTENT AS WELL. THINGS TO PICK OUT AS
POTENTIAL ENHANCEMENTS TO THIS FORECAST ARE A SLIGHT INCREASE IN
UPSLOPE FLOW AND UPLIFT IN THE WRN MTS THIS EVENING. THIS HAS
RESULTED IN A FEW HOUR PERIOD OF WORSE FCST CONDITIONS FOR THOSE
LOCATIONS - BUT EVEN THAT NEVER DROPS ANY SITE TO LIFR. SOME IFR
VSBYS ARE LIKELY THE WORST OF THE THINGS TO DEAL WITH TONIGHT.
CIGS WILL PROBABLY HOLD ABOVE FL010 ALL NIGHT...EXCEPT PERHAPS AT
JST...BUT PROB SO LOW THAT I HAVE NOT INCLUDED IT WITH THIS PKG.
MONDAY BRINGS SIGNIFICANT IMPROVEMENT TO CLOUDS AND VSBYS. SFC
RIDGE TO THE WEST INCHES CLOSER AND WE LOSE THE CYCLONIC LLVL
FLOW...AS IT BECOMES MORE-NEUTRAL. LAKE MOISTURE STILL DRAWN DOWN
FROM THE N WILL KEEP THE CLOUDS OVER THE NRN TIER...BUT SERN
TERMINALS WILL CLEAR OUT BY THE LATE AFTN...AND EVEN JST MIGHT
SCT-OUT. HIGH PRES AXIS MAKES IT OVERHEAD TUES AM...AND LITTLE
CLOUD AND ONLY LIGHT WIND IN STORE.
OUTLOOK...
TUE...CLOUDS INCREASE W-E LATE.
TUE NIGHT-WED NIGHT...SIG RESTRICTIONS POSS S IN S+
THU...MVFR N...VFR ELSEWHERE.
FRI...NSW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...LAMBERT
AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
239 PM EST SUN MAR 3 2013
.SYNOPSIS...
A SLOW MOVING UPPER LOW OVER THE NORTHEASTERN STATES WILL EXIT OFF
THE NEW ENGLAND COAST BY LATE MONDAY ALLOWING WEAK HIGH PRESSURE
TO BUILD ACROSS THE LOCAL AREA. LOW PRESSURE WILL DEVELOP IN THE
HIGH PLAINS SUNDAY AND MONDAY AND TAKE A TRACK THROUGH THE OHIO
VALLEY AND MID-ATLANTIC STATES TUESDAY NIGHT AND WEDNESDAY. THIS
STORM WILL PROBABLY PASS TO THE SOUTH OF THE STATE...BUT WILL MOST
LIKELY BRING SNOW INTO SOUTHERN PENNSYLVANIA IN THE MIDDLE OF THE
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
FORECAST STRONGLY CONTINUOUS...AND FLURRIES OR LIGHT SNOW EXPECTED
FOR THE ENTIRE NIGHT. RECENT HRRR AND RUC/RAP HAVE BEEN INDICATING
THAT WE COULD GET SOME ENHANCED LLVL OMEGA THIS EVENING AS AN
UPPER LEVEL LOW FILLS AND PASSES N-S THRU OH. WILL KEEP POPS HIGH
THEN PLAY A GRADUAL DECREASE IN POPS/SNOW INTENSITY AND AMOUNTS
AFTER MIDNIGHT. BUT THE FLOW DOES NOT CHANGE DIRECTION AND THE
PRES GRADIENT STAYS TIGHT. SHOULD BE BREEZY WITH 10MPH+ WINDS ALL
NIGHT. THE FLUFFINESS OF THE SNOW IN THIS DRY AIR MASS AND COLD
CLOUD TEMPS RESULTED IN SLR/S IN THE 30:1 RANGE SUN MORNING.
THEREFORE...ACCUMS OF A DUSTING TO AN INCH PROBABLE OVER THE NWRN
HALF OF THE AREA...WITH 1-3 IN THE FAR NRN TIER AND IN THE
LAURELS. TEMPS ALREADY BELOW NORMALS...BUT CLOUD COVER WILL HELP
TO KEEP THEM GOING TOO FAR BELOW NORMAL MINS BY MON MORNING.
&&
.SHORT TERM /MONDAY/...
SFC HIGH PRESSURE RIDGE TO THE WEST INCHES CLOSER AND 5H HEIGHTS
RISE GREATLY OVER THE GREAT LAKES AND OH VALLEY AND SOMEWHAT HERE
AS WELL. LLVL PRES GRADIENT STAYS TIGHT DURING THE DAY AND MIXING
DEEPER THAN SUNDAY SHOULD ENHANCE THE WINDS IN THE AFTN. THE CLOUD
DECK WILL BECOME MORE-DIFFUSE THROUGH THE MORNING AND CLEARING
POSSIBLE ACROSS THE SOUTH AND EAST-CENTRAL COS IN THE AFTN. NW
FLOW STILL DOMINATES MUCH OF THE DAY...BUT RELAXES AND BECOMES
SLIGHTLY ANTI-CYCLONIC LATER IN THE DAY. THIS ALSO POINTS TO A
SUBSIDENCE OF THE SHSN...BUT THEY WILL LIKELY HOLD ON LONGEST IN
THE NRN TIER. CLOUDS WILL LINGER EVEN LONGER...PERHAPS STAYING
NEAR 100PCT THRU THE EVENING HRS. WILL CONTINUE TO MENTION LIGHT
ACCUMS AND LIKELY POPS IN THE MTNS IN THE MORNING...BUT TAPER THEM
OFF LATER. DUE TO THE POSSIBILITY OF SUN IN THE SRN TIER AND ESP
THE SE...TEMPS SHOULD GET A LITTLE MILDER - BUT STILL BELOW NORMAL
ON MONDAY AFTN.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
09Z UPDATE...
THE MAIN FOCUS OF THIS EXTENDED PERIOD CONTINUES TO BE MODEL
HANDLING OF MIDWEEK STORM SYSTEM...WHICH HAS THE POTENTIAL TO
BRING ACCUMULATING SNOWFALL TO CENTRAL AND SOUTHERN PA.
WITHOUT BEING TOO REACTIVE TO THE LATEST RUNS AND ENSEMBLES... IT
IS CLEAR THAT THE NAM/SREF/GFS/GEM ARE IN A DIFFERENT CAMP THAN
THE ECMWF...AS THE FORMER HAS TRENDED FARTHER NORTH OVER THE PAST
24 TO 36 HOURS WHILE THE EURO CONTINUES TO MIRROR PREVIOUS (2 DAY
OLD) RUNS OF THE GFS KEEPING MOST QPF SOUTH OF THE MASON/DIXON.
THINK THE OVERALL MESSAGE IS THAT THE AMERICAN AND CANADIAN MODELS
ARE KEEPING THE PRIMARY LOW STRONGER WITH DELAYED COASTAL PHASING...
PERHAPS QUITE SIMILAR TO THE LAST UNPHASED MILLER-B SYSTEM WE SAW
LAST FRIDAY. GFS EVEN INTRODUCES A DRY SLOT INTO WV WITH 850 TEMPS
ABOVE ZERO NOSING TOWARDS THE LAUREL HIGHLANDS EARLY WEDNESDAY AS
A RESULT OF THE DELAYED 2NDARY DEVELOPMENT. OF COURSE...3 DAYS OUT
THESE DETAILS WILL CHANGE...BUT IT`S WORTH ATTEMPTING TO DIAGNOSE
WHY OUR MODELS ARE SHIFTING QPF NORTHWARD WHILE THE PREVAILING
DOWNSTREAM BLOCK REMAINS IN PLACE...AND THE ECMWF FOR NOW ISN`T
SHOWING THE SAME TREND.
WITH THE ABOVE IN MIND...TWEAKED POPS...QPF AND SNOWFALL TOWARD
THE SREF AND GFS SOLUTIONS...BUT USED ONLY 50% OF THE GFS QPF AT
THIS TIME FOR THE SOUTHERN THIRD OF CENTRAL PA. SHOULD THE TREND
CONTINUE...IT IS POSSIBLE THAT CENTRAL PA BECOMES THE SWEET SPOT
BETWEEN THE DECAYING PRIMARY AND 2NDARY COASTAL DEVELOPMENT. AT
THIS TIME HOWEVER...STILL EXPECT THE GREATEST PROBABILITY OF HEAVY
SNOW OVER NORTHERN VIRGINIA AND MARYLAND...WHICH IS THE CONSENSUS
SOLUTION AT THIS TIME.
PREVIOUS DISCUSSION...
MODELS AND ENSEMBLES ARE COMING INTO BETTER AGREEMENT ON THE TRACK
OF THE MIDWEEK STORM HEADED OUR WAY FROM THE MID MISS VALLEY.
GRANTED...THERE/S STILL QUITE A BIT OF UNCERTAINTY...SINCE THE U.S.
MODELS...15Z AND 21Z SREF...ALONG WITH THE 06Z THROUGH 18Z GEFS HAVE
ALL TRENDED NORTH BY 50-100 NM WITH THE AXIS OF HEAVIEST QPF. THE
LATEST NAEFS AND EC ARE STILL ON THE SOUTHERN ENVELOPE OF SOLUTIONS
IN TRACKING THE SFC LOW NEAR OR JUST TO THE NORTH OF THE NC/WVA
LINE. THE NAEFS IS A TAD FURTHER NORTH...WHILE THE EC/S APPROX 530
DAM CLOSED LOW CENTER IS TAKEN ACROSS TENN AND NC. ALTHOUGH OUR
SOUTHERN COUNTIES ARE UNDER THE GUN FOR SOME POTENTIALLY HEAVY
SNOW...THE BIGGEST SIGNAL FOR AT LEAST SOME LIGHT SNOW ACROSS MUCH
OF CENTRAL /AND PERHAPS EVEN NCENT/ PENN IS THE BROAD AREA OF
ANOMALOUS EASTERLY LOW TO MID LEVEL FLOW BETWEEN THIS DEEP LOW...AND
THE OMEGA BLOCK ACROSS SERN CANADA.
THE MAIN THING TO EMPHASIZE AT THIS EARLY POINT IN TIME...IS THE
HIGH CONFIDENCE/POTENTIAL FOR A HIGH IMPACT STORM WITH HEAVY SNOW
SOMEWHERE ACROSS THE CENTRAL APPALACHIANS TO THE MID ATLANTIC
PIEDMONT...WITH OBVIOUSLY LESS CONFIDENCE IN THE STORM TRACK.
MODIFIED GRIDDED DATA TO INDICATE LIKELY POPS...WITH UP TO SEVERAL
INCHES OF STORM TOTAL SNOWFALL ACROSS THE SOUTHERN HALF OF PENN LATE
TUESDAY THROUGH WEDNESDAY.
PREVIOUS AFTERNOON DISCUSSION FOLLOWS...
PERSISTENT UPPER TROF OVER THE NORTHEASTERN UNITED STATES WILL GET
A QUICK REINFORCING SHOT OF COOLER AIR ON MONDAY BEFORE IT EXITS
TO THE NORTHEAST. LOWS SUN NIGHT WILL BE SLIGHTLY COOLER THAN THE
NIGHT BEFORE...WITH HIGHS MON JUST A FEW DEGREES HIGHER THAN SUNDAY.
TUESDAY A WEAK SFC RIDGE WILL BE IN PLACE OVER CENTRAL
PA...BRINGING QUIET WEATHER ALONG WITH WARMER TEMPERATURES.
VIGOROUS UPPER TROF WILL BE SLIDING ACROSS CENTRAL PLAINS
TUES...AND FCST TO DIVE SEWD TOWARD THE CAROLINAS...SPINNING UP A
SFC LOW OVER N CAROLINA/VIRGINA ON WED. HIGH LATITUDE BLOCKING AND
EASTWARD PROPAGATION OF SHORTWAVE ENERGY SHOULD KEEP CENTER OF
MAIN LOW TO OUR SOUTH...SLIPPING OFF THE COAST S OF DELMARVA.
SYSTEM WILL HAVE SOME PHASING ISSUES...WITH SECONDARY WEAKER SFC
LOW EDGING TOWARD W PA FROM OHIO VALLEY...BUT IMPACT TO EAST COAST
WILL BE CENTERED AROUND WED-WED NIGHT. MODELS STILL HAVE SOME
DIFFERENCES...BUT GENERALLY MORE IN LINE THAN PREVIOUS RUNS...WITH
A SOUTHERN TRACK BRINGING HEAVY SNOW TO THE VIRGINIA`S APPEARING
MOST LIKELY AT THIS TIME...WITH CONSENSUS AMONG 12Z MODELS TAKING
THE BULK OF QPF WELL SOUTH OF THE MASON DIXON LINE. AS
USUAL...EXPECT MODELS TO WAVER OVER THE NEXT SEVERAL DAYS...BUT
THE POTENTIAL EXISTS FOR SOME ACCUMULATING SNOW OR RAIN LATE
TUESDAY INTO WEDNESDAY NIGHT...BUT ALL OF THE MOST IMPORTANT
DETAILS REMAIN UNCLEAR AT THIS EARLY TIME.
BEHIND THIS SYSTEM FOR LATE WEEK INTO THE WEEKEND...MINIMAL COLD
AIR TO BE SEEN AS FLOW BECOMES WESTERLY. BY FRI...HIGHS SHOULD BE
IN THE 40S AREA-WIDE...AND SEVERAL DEGREES HIGHER ON SAT WITH A
PLEASANT SPRING DAY IN STORE.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
PERSISTENCE FORECAST REMAINS THE PHRASE FOR THE FCST PERIOD.
CLIMO NW FLOW PATTERN YIELDS GENERALLY MVFR/IFR CIGS IN THE
BFD/JST AND MVFR IN AOO/UNV. DRYING ON DOWNSLOPE IMPROVES
CONDITIONS EVEN MORE IN IPT/MDT/LNS. PRES GRADIENT KEEPING WINDS
IN THE 10-15KT RANGE WITH OCCASIONAL GUSTS INTO THE 20S ALMOST
EVERYWHERE. THE GRADIENT DOES NOT SLACKEN THROUGH THE NIGHT NOR ON
MONDAY. WILL KEEP WINDS PERSISTENT AS WELL. THINGS TO PICK OUT AS
POTENTIAL ENHANCEMENTS TO THIS FORECAST ARE A SLIGHT INCREASE IN
UPSLOPE FLOW AND UPLIFT IN THE WRN MTS THIS EVENING. THIS HAS
RESULTED IN A FEW HOUR PERIOD OF WORSE FCST CONDITIONS FOR THOSE
LOCATIONS - BUT EVEN THAT NEVER DROPS ANY SITE TO LIFR. SOME IFR
VSBYS ARE LIKELY THE WORST OF THE THINGS TO DEAL WITH TONIGHT.
CIGS WILL PROBABLY HOLD ABOVE FL010 ALL NIGHT...EXCEPT PERHAPS AT
JST...BUT PROB SO LOW THAT I HAVE NOT INCLUDED IT WITH THIS PKG.
MONDAY BRINGS SIGNIFICANT IMPROVEMENT TO CLOUDS AND VSBYS. SFC
RIDGE TO THE WEST INCHES CLOSER AND WE LOSE THE CYCLONIC LLVL
FLOW...AS IT BECOMES MORE-NEUTRAL. LAKE MOISTURE STILL DRAWN DOWN
FROM THE N WILL KEEP THE CLOUDS OVER THE NRN TIER...BUT SERN
TERMINALS WILL CLEAR OUT BY THE LATE AFTN...AND EVEN JST MIGHT
SCT-OUT. HIGH PRES AXIS MAKES IT OVERHEAD TUES AM...AND LITTLE
CLOUD AND ONLY LIGHT WIND IN STORE.
OUTLOOK...
TUE...CLOUDS INCREASE W-E LATE.
TUE NIGHT-WED NIGHT...SIG RESTRICTIONS POSS S IN S+
THU...MVFR N...VFR ELSEWHERE.
FRI...NSW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...DEVOIR/LAMBERT/RXR
AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1048 PM EST SAT MAR 2 2013
.SYNOPSIS...
A STAGNANT UPPER LEVEL LOW PRESSURE AREA OVER THE NORTHEASTERN
STATES WILL MOVE TO THE EAST OVER THE NEXT TWO DAYS. WEAK HIGH
PRESSURE WILL MOVE IN FOR LATE MONDAY AND EARLY TUESDAY. LOW
PRESSURE WILL DEVELOP IN THE HIGH PLAINS SUNDAY AND MONDAY AND
TAKE A TRACK THROUGH THE OHIO VALLEY AND MID-ATLANTIC STATES
TUESDAY NIGHT AND WEDNESDAY. THIS STORM WILL PROBABLY PASS TO THE
SOUTH OF THE STATE...BUT IT COULD BRING SOME SNOW OR RAIN TO
SOUTHERN PENNSYLVANIA IN THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
VERY MINOR CHANGES MADE TO THE OVERNIGHT PERIOD. REFER TO THE LONG
TERM PERIOD FOR SOME UPWARD MODIFICATIONS TO POPS AND SNOW POTENTIAL
FOR THE MIDWEEK PERIOD.
A WELL-DEFINED PLUME OF DEEPER MOISTURE WAS ROTATING SWD /ALOGN WITH
MORE ILL-DEFINED SPOKES OF UPPER ENERGY AROUND THE BACK SIDE OF THE
VERY SLOW MOVING UPPER LOW /CENTERED NEAR KNYC LATE THIS EVENING/.
SNOW SHOWERS WILL BE FREQUENT ACROSS THE NRN AND WESTERN
MTNS...WHERE MANY LOCATIONS WILL SEE AN ADDITIONAL FRESH COATING TO
ONE INCH OF SNOW OVERNIGHT. THIS TREND IS IN LINE WITH
THE 20Z HRRR AND EARLIER 12/18Z 4 AND 12KM VERSIONS OF THE NAM.
SOME OF THE RIDGE TOPS /ESPECIALLY ACROSS THE LAURELS/ COULD SEE
UP TO 2 INCHES OF POWDERY SNOW.
MAINLY FLURRIES ARE EXPECTED ACROSS THE SCENT AND SERN
ZONES...WHILE A FEW SNOW SHOWERS WITH 2SM VSBYS COULD SPILL OFF
THE ALLEGHENIES AND MAKE IT TO THE CENTRAL MTNS AND MIDDLE SUSQ
VALLEY...GIVING A DUSTING IN SOME AREAS.
OVERNIGHT LOW TEMPS WILL VARY FROM THE MID TEENS ACROSS THE NW...TO
THE MID 20S IN THE SE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
MORE OF THE SAME EXPECTED FOR SUNDAY AS UPPER LOW DEPARTS ONLY
SLOWLY TO THE NORTHEAST. CLOUDS AND SLIGHTLY COOLER THAN NORMAL
MAXES WILL PREVAIL AGAIN ON SUNDAY. CONTINUING BREEZY NW WIND AND
SMALL CHANCES FOR SNOW SHOWERS AND FLURRIES...TAPERING TO NIL PAST
THE RIDGE AND VALLEY REGION.
HIGHS WILL BE WITHIN A DEGREE OR TWO OF SATURDAY AFTERNOON
READINGS RANGING FROM THE MID 20S NORTHWEST TO AROUND 40
SOUTHEAST. PERHAPS JUST A TOUCH COOLER IN THE NW WHERE 8H TEMPS GO
DOWN ONE OR TWO DEGS C.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
03Z SUNDAY UPDATE...
MODELS AND ENSEMBLES ARE COMING INTO BETTER AGREEMENT ON THE TRACK
OF THE MIDWEEK STORM HEADED OUR WAY FROM THE MID MISS VALLEY.
GRANTED...THERE/S STILL QUITE A BIT OF UNCERTAINTY...SINCE THE U.S.
MODELS...15Z AND 21Z SREF...ALONG WITH THE 06Z THROUGH 18Z GEFS HAVE
ALL TRENDED NORTH BY 50-100 NM WITH THE AXIS OF HEAVIEST QPF. THE
LATEST NAEFS AND EC ARE STILL ON THE SOUTHERN ENVELOPE OF SOLUTIONS
IN TRACKING THE SFC LOW NEAR OR JUST TO THE NORTH OF THE NC/WVA
LINE. THE NAEFS IS A TAD FURTHER NORTH...WHILE THE EC/S APPROX 530
DAM CLOSED LOW CENTER IS TAKEN ACROSS TENN AND NC. ALTHOUGH OUR
SOUTHERN COUNTIES ARE UNDER THE GUN FOR SOME POTENTIALLY HEAVY
SNOW...THE BIGGEST SIGNAL FOR AT LEAST SOME LIGHT SNOW ACROSS MUCH
OF CENTRAL /AND PERHAPS EVEN NCENT/ PENN IS THE BROAD AREA OF
ANOMALOUS EASTERLY LOW TO MID LEVEL FLOW BETWEEN THIS DEEP LOW...AND
THE OMEGA BLOCK ACROSS SERN CANADA.
THE MAIN THING TO EMPHASIZE AT THIS EARLY POINT IN TIME...IS THE
HIGH CONFIDENCE/POTENTIAL FOR A HIGH IMPACT STORM WITH HEAVY SNOW
SOMEWHERE ACROSS THE CENTRAL APPALACHIANS TO THE MID ATLANTIC
PIEDMONT...WITH OBVIOUSLY LESS CONFIDENCE IN THE STORM TRACK.
MODIFIED GRIDDED DATA TO INDICATE LIKELY POPS...WITH UP TO SEVERAL
INCHES OF STORM TOTAL SNOWFALL ACROSS THE SOUTHERN HALF OF PENN LATE
TUESDAY THROUGH WEDNESDAY.
PREVIOUS AFTERNOON DISCUSSION FOLLOWS...
PERSISTENT UPPER TROF OVER THE NORTHEASTERN UNITED STATES WILL GET
A QUICK REINFORCING SHOT OF COOLER AIR ON MONDAY BEFORE IT EXITS
TO THE NORTHEAST. LOWS SUN NIGHT WILL BE SLIGHTLY COOLER THAN THE
NIGHT BEFORE...WITH HIGHS MON JUST A FEW DEGREES HIGHER THAN SUNDAY.
TUESDAY A WEAK SFC RIDGE WILL BE IN PLACE OVER CENTRAL
PA...BRINGING QUIET WEATHER ALONG WITH WARMER TEMPERATURES.
VIGOROUS UPPER TROF WILL BE SLIDING ACROSS CENTRAL PLAINS
TUES...AND FCST TO DIVE SEWD TOWARD THE CAROLINAS...SPINNING UP A
SFC LOW OVER N CAROLINA/VIRGINA ON WED. HIGH LATITUDE BLOCKING AND
EASTWARD PROPAGATION OF SHORTWAVE ENERGY SHOULD KEEP CENTER OF
MAIN LOW TO OUR SOUTH...SLIPPING OFF THE COAST S OF DELMARVA.
SYSTEM WILL HAVE SOME PHASING ISSUES...WITH SECONDARY WEAKER SFC
LOW EDGING TOWARD W PA FROM OHIO VALLEY...BUT IMPACT TO EAST COAST
WILL BE CENTERED AROUND WED-WED NIGHT. MODELS STILL HAVE SOME
DIFFERENCES...BUT GENERALLY MORE IN LINE THAN PREVIOUS RUNS...WITH
A SOUTHERN TRACK BRINGING HEAVY SNOW TO THE VIRGINIA`S APPEARING
MOST LIKELY AT THIS TIME...WITH CONSENSUS AMONG 12Z MODELS TAKING
THE BULK OF QPF WELL SOUTH OF THE MASON DIXON LINE. AS
USUAL...EXPECT MODELS TO WAVER OVER THE NEXT SEVERAL DAYS...BUT
THE POTENTIAL EXISTS FOR SOME ACCUMULATING SNOW OR RAIN LATE
TUESDAY INTO WEDNESDAY NIGHT...BUT ALL OF THE MOST IMPORTANT
DETAILS REMAIN UNCLEAR AT THIS EARLY TIME.
BEHIND THIS SYSTEM FOR LATE WEEK INTO THE WEEKEND...MINIMAL COLD
AIR TO BE SEEN AS FLOW BECOMES WESTERLY. BY FRI...HIGHS SHOULD BE
IN THE 40S AREA-WIDE...AND SEVERAL DEGREES HIGHER ON SAT WITH A
PLEASANT SPRING DAY IN STORE.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
NW FLOW REGIME WILL REMAIN ENTRENCHED ACROSS CENTRAL PA FOR THE
NEXT 36 HOURS. ANY BREAKS IN THE CLOUDS WILL CLOSE UP THIS EVENING
AND CIGS WILL LOWER AGAIN...WITH MVFR-OCNL IFR CONDITIONS IN
PLACE ACROSS WESTERN HIGHER TERRAIN AS UPSLOPE FLOW KEEPS LOW
CLOUDS AND SCATTERED SNOW SHOWERS REMAIN LOCKED IN. CENTRAL
TERMINALS SUCH AS ALTOONA AND STATE COLLEGE WILL REMAIN IN THE
2-4KFT RANGE FOR CEILINGS. EXPECT THEM TO BE VFR MOST OF THE TIME
DURING THE REST OF THE EVE AND AGAIN SUN AFTN...BUT A FEW
FLURRIES AND 2KFT CIGS COULD DRIFT IN FM THE NW - ESP TONIGHT.
MDT/LNS WILL STAY VFR. WINDS WILL REMAIN GUSTY OUT OF THE
NORTHWEST.
OUTLOOK...
MON-TUE AM...SCATTERED SNOW SHOWERS WITH INTERMITTENT CIG/VSBY
REDUCTIONS N AND W. VFR SE.
TUE PM-WED...STORM WITH A TRACK THRU MID ATLC STATES WILL BRING
THE POSS OF LOWERED CIGS/VSBYS TO THE AREA - ESP THE SRN HALF OF
THE AREA.
WED PM-THU...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...LAMBERT
SHORT TERM...DANGELO
LONG TERM...LAMBERT/RXR
AVIATION...DANGELO/GARTNER
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS SPOKANE WA
958 PM PST Sat Mar 2 2013
.SYNOPSIS...After the warm and mostly dry conditions today, a
strong storm system will bring the threat of rain, mountain snow,
and gusty winds tonight and Sunday. Monday should be seasonal and
dry, then a slow moving low pressure system will bring a return to
unsettled weather conditions Tuesday through Thursday.
&&
.DISCUSSION...
Some forecast changes have been made through Sunday. An upper
level trough passing through the region tonight will send a strong
cold front through the area. The main impact from this front will
be breezy to windy conditions overnight into Sunday as well as
light to moderate snow accumulations in the mountains.
The NAM and ECMWF model has the best handle on the current
situation with the GFS model ignored due to poor handling of
relative humidity through the atmospheric column this evening (wet
bias). A mid level front stretching from the Blues and Camas
Prairie to the Central Panhandle Mountains will exit the area this
evening with the surface cold front quickly following overnight.
Areas of light rain and high mountain snow will continue through
the evening in these areas with the mid level front over the area.
Meanwhile the surface cold front went through Wenatchee at 7 PM
and satellite and surface observations show a strong rain shadow
east of the Cascades with 850mb winds out of the west-southwest at
30 knots. With this being a fast moving front tonight and strong
downslope flow this rain shadow may extend into most of Eastern
Washington as well as the Lewiston area with the latest HRRR and
00z NAM keeping most of the precipitation north and east of the
Columbia Basin. Also the best instability aloft will be passing
north of these areas through British Columbia...northern
Washington...and the north Idaho Panhandle under the coldest pool
of 500mb temps of -33 to -35C. With a more substantial rain shadow
expected precipitation chances were lowered for most of Central
and Eastern Washington tonight. Behind the front a very
pronounced dry slot on water vapor imagery will be aimed directly
at central and southern Washington extending into the Camas
Prairie and Central Panhandle Mountains. This will greatly limit
the degree of snow showers Sunday morning in these areas and thus
precipitation chances and snow accumulations were lowered. Could
see a bit more snow shower activity over the North Idaho Panhandle
and northeast Washington Mountains Sunday morning under the cold
pool aloft.
With strong cold advection behind the cold front and 850mb winds
of 25-35 knots breezy to windy conditions will develop overnight
into Sunday and the wind forecast looks on track. With 850mb temps
falling to near -5C Sunday morning mountain low temperatures were
adjusted downward with other minor changes elsewhere. JW
&&
.AVIATION...
06Z TAFS: Winds will increase with gusts in the 20-35 mph range
overnight into Sunday afternoon along and behind a strong cold front
passage. Brief rain is possible with the front passage tonight at
KGEG/KSFF/KCOE/KPUW/KLWS. Behind the front significant drying will
lead to clearing skies at the TAF sites in the 08-15z time frame
from west to east. Then under the cold air associated with the
trough will see an increase in cumulus clouds as the atmosphere
destabilizes during the day on Sunday. Shower chances will increase
Sunday afternoon, especially in the Eastern Washington and North
Idaho Mountains. A few may still fall around the KGEG-KCOE-KPUW
region but the risk is slight. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 31 41 26 42 30 46 / 50 40 0 0 0 20
Coeur d`Alene 32 39 26 42 29 47 / 80 60 10 0 0 20
Pullman 32 41 29 44 30 50 / 70 40 0 0 0 10
Lewiston 40 48 32 50 34 56 / 50 20 10 0 0 10
Colville 31 43 26 49 28 50 / 50 30 0 0 0 40
Sandpoint 32 38 29 41 29 44 / 100 70 20 0 0 20
Kellogg 34 36 29 42 28 46 / 100 100 50 0 0 20
Moses Lake 36 54 26 47 31 49 / 10 0 0 0 0 40
Wenatchee 35 52 29 46 32 48 / 10 0 0 0 10 40
Omak 33 47 22 43 26 45 / 20 0 0 0 10 40
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
817 PM PST Sat Mar 2 2013
.SYNOPSIS...After the warm and mostly dry conditions today, a
strong storm system will bring the threat of rain, mountain snow,
and gusty winds tonight and Sunday. Monday should be seasonal and
dry, then a slow moving low pressure system will bring a return to
unsettled weather conditions Tuesday through Thursday.
&&
.DISCUSSION...
Some forecast changes have been made through Sunday. An upper
level trough passing through the region tonight will send a strong
cold front through the area. The main impact from this front will
be breezy to windy conditions overnight into Sunday as well as
light to moderate snow accumulations in the mountains.
The NAM and ECMWF model has the best handle on the current
situation with the GFS model ignored due to poor handling of
relative humidity through the atmospheric column this evening (wet
bias). A mid level front stretching from the Blues and Camas
Prairie to the Central Panhandle Mountains will exit the area this
evening with the surface cold front quickly following overnight.
Areas of light rain and high mountain snow will continue through
the evening in these areas with the mid level front over the area.
Meanwhile the surface cold front went through Wenatchee at 7 PM
and satellite and surface observations show a strong rain shadow
east of the Cascades with 850mb winds out of the west-southwest at
30 knots. With this being a fast moving front tonight and strong
downslope flow this rain shadow may extend into most of Eastern
Washington as well as the Lewiston area with the latest HRRR and
00z NAM keeping most of the precipitation north and east of the
Columbia Basin. Also the best instability aloft will be passing
north of these areas through British Columbia...northern
Washington...and the north Idaho Panhandle under the coldest pool
of 500mb temps of -33 to -35C. With a more substantial rain shadow
expected precipitation chances were lowered for most of Central
and Eastern Washington tonight. Behind the front a very
pronounced dry slot on water vapor imagery will be aimed directly
at central and southern Washington extending into the Camas
Prairie and Central Panhandle Mountains. This will greatly limit
the degree of snow showers Sunday morning in these areas and thus
precipitation chances and snow accumulations were lowered. Could
see a bit more snow shower activity over the North Idaho Panhandle
and northeast Washington Mountains Sunday morning under the cold
pool aloft.
With strong cold advection behind the cold front and 850mb winds
of 25-35 knots breezy to windy conditions will develop overnight
into Sunday and the wind forecast looks on track. With 850mb temps
falling to near -5C Sunday morning mountain low temperatures were
adjusted downward with other minor changes elsewhere. JW
&&
.AVIATION...
00Z TAFS: Cold front passes with increasing precip this evening,
before chances start to wind down from the west late tonight into
Sunday morning. Expect mainly rain around TAF sites, though some
snow may mix in overnight into Sunday morning closer to the ID
panhandle. Predominantly VFR at TAF sites; brief MVFR cigs
possible within steadier precipitation. Breezy conditions late
tonight with the frontal and vort max passage, then again Sunday
afternoon in the unstable, mixed atmosphere. Shower chances linger
in the instability Sunday afternoon, especially near the mountains.
A few may still fall around the KGEG-KCOE-KPUW region but the
risk is slight. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 31 41 26 42 30 46 / 50 40 0 0 0 20
Coeur d`Alene 32 39 26 42 29 47 / 80 60 10 0 0 20
Pullman 32 41 29 44 30 50 / 70 40 0 0 0 10
Lewiston 40 48 32 50 34 56 / 50 20 10 0 0 10
Colville 31 43 26 49 28 50 / 50 30 0 0 0 40
Sandpoint 32 38 29 41 29 44 / 100 70 20 0 0 20
Kellogg 34 36 29 42 28 46 / 100 100 50 0 0 20
Moses Lake 36 54 26 47 31 49 / 10 0 0 0 0 40
Wenatchee 35 52 29 46 32 48 / 10 0 0 0 10 40
Omak 33 47 22 43 26 45 / 20 0 0 0 10 40
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
530 AM CST SUN MAR 3 2013
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
325 AM CST SUN MAR 3 2013
MAIN FOCUS IS ON THE LONG PERIOD OF ACCUMULATING SNOW LATE TONIGHT
THROUGH TUESDAY
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT
ANALYSIS SHOWED A POTENT SHORTWAVE TROUGH OVER SOUTHERN BRITISH
COLUMBIA INTO WASHINGTON STATE...RIDGING FROM BAJA CALIFORNIA INTO
SOUTHERN SASKATCHEWAN...AND A SHORTWAVE TROUGH DROPPING INTO EASTERN
WISCONSIN. PLENTIFUL UPPER LEVEL MOISTURE WAS STREAMING NORTH OUT OF
THE TROPICAL EAST PACIFIC AND THROUGH THE TOP OF THE UPPER RIDGE...
MANIFESTING ITSELF AS CIRRUS CLOUD COVER OVER THE DAKOTAS INTO
WESTERN MINNESOTA. EAST OF THIS CIRRUS...AN ALTOSTRATUS DECK WAS
PRESENT ACROSS MUCH OF MINNESOTA AND IOWA. THIS DECK IS A RESULT OF
RELATIVELY HIGHER MOISTURE OVER THE DAKOTAS GETTING ISENTROPICALLY
LIFTED. 00Z SOUNDING DATA SHOWED PRECIPITABLE WATER OF 0.16 INCHES
AT MPX...OR 66 PERCENT OF NORMAL...COMPARED TO 0.4 INCHES AT BIS AND
ABR OR 175 PERCENT OF NORMAL. BIG 850MB TEMPERATURE DIFFERENCE
TOO...WITH MPX AT -8C COMPARED TO AROUND 3C AT BIS AND ABR. DESPITE
THE PRESENCE OF THE ALTOSTRATUS DECK AND SOME LIGHT RETURNS ON
REGIONAL RADAR...NOTHING HAS REACHED THE SURFACE DUE TO DRIER LOW
LEVEL AIR SEEN ON THAT 00Z MPX SOUNDING. DRY AIR SEEN ON THE 00Z GRB
SOUNDING HAS ALSO PREVENTED MUCH FOR CLOUDS WITH THE SHORTWAVE
DROPPING THROUGH EASTERN WISCONSIN. AT THE SURFACE...A RIDGE OF HIGH
PRESSURE ENCOMPASSED MUCH OF THE WESTERN GREAT LAKES WHILE LOW
PRESSURE WAS DEEPENING IN SOUTHERN ALBERTA. LASTLY...REGARDING THAT
POTENT SHORTWAVE TROUGH...00Z RAOB DATA SHOWED SOME PRETTY
IMPRESSIVE 500MB HEIGHT FALLS...AROUND 100 METERS IN 12 HOURS.
ALL MODELS CONTINUE TO INDICATE THAT THE LONG PERIOD OF SNOW WILL
OCCUR FROM THE NORTHERN PLAINS SOUTHEAST INTO PORTIONS OF THE
FORECAST AREA. THREE DISTINCT FORCING MECHANISMS ARE GOING TO GOVERN
THIS SNOW...WITH THE LAST TWO ITEMS MODULATING THE INTENSITY AND
PLACEMENT...
1. A LOW TO MID LEVEL FRONTOGENESIS ZONE...WHICH CAN ALREADY BE SEEN
IN THE 00Z SOUNDING DATA NOTED BY THE SHARP DIFFERENCE IN 850MB
TEMPS BETWEEN MPX AND ABR.
2. A HARD TO SEE SHORTWAVE ON WATER VAPOR CURRENTLY IN SOUTHERN
IDAHO PROGGED TO MOVE WEST TO EAST THROUGH THE FORECAST AREA ON
MONDAY
3. THE POTENT UPPER TROUGH WHICH DROPS SOUTHEAST OUT OF THE NORTHERN
PLAINS ON MONDAY AND INTO THE MID-MISSISSIPPI VALLEY BY LATE TUESDAY
OVERALL...MODELS AGREE REALLY WELL TONIGHT INTO MONDAY IN THE
HANDLING OF THE FRONTOGENESIS ZONE AND SHORTWAVE MOVING THROUGH.
BETWEEN 00-06Z TONIGHT...SOUTH WINDS REALLY PICK UP ON THE 285-290K
SURFACES IN SOUTHWEST MINNESOTA AHEAD OF THE APPROACHING
SHORTWAVE...HELPING TO INCREASE THE INTENSITY OF THE FRONTOGENESIS
ZONE. COMBINED WITH PACIFIC MOISTURE ALREADY PRESENT IN THE
DAKOTAS...SNOW SHOULD EASILY BREAK OUT. AS THE SHORTWAVE PRESSES
EAST TOWARDS THE AREA AFTER 06Z...THE FRONTOGENESIS ZONE SHIFTS EAST
WITH IT...IMPACTING LOCATIONS WEST OF THE MISSISSIPPI RIVER. HIGHER
HORIZONTAL RESOLUTION QPF DATA FROM THE 03.00Z NAM...HIRES-ARW/NMM
AND REGIONAL CANADIAN SUGGEST ANYWHERE FROM 0.25-0.30...HIGHEST IN
THE AUSTIN/CHARLES CITY AREA. EVEN HIGHER AMOUNTS LOOK POSSIBLE TO
THE NORTHWEST. SOUNDINGS DEPICT ONLY A 75MB LAYER OF DENDRITIC
GROWTH...WAY UP AROUND 600MB...WITH LIFT THROUGHOUT A LOT OF THE
COLUMN. THUS...THINKING SNOW TO WATER RATIOS SHOULD STAY AROUND 10
TO 1...YIELDING UPWARDS OF 2-3 INCHES BY 12Z. THE FRONTOGENESIS ZONE
CONTINUES TO PUSH EAST DURING THE DAY MONDAY BY THE SHORTWAVE...
EVENTUALLY STALLING OUT OVER THE SOUTHWEST 2/3 OF THE FORECAST AREA
FOR THE AFTERNOON. THE HEAVIEST PRECIPITATION LOOKS TO OCCUR IN THE
MORNING WITH ENHANCEMENT FROM THE SHORTWAVE BEFORE THE SHORTWAVE
LIFTS OFF. COULD SEE UPWARDS OF 0.25 INCH DURING THE MORNING IN
SOUTHEAST MN INTO PORTIONS OF NORTHEAST IOWA...EQUATING TO ANOTHER
2-3 INCHES OF SNOW. THUS...FOR THE 06-18Z MONDAY PERIOD...TOTALS OF
4-5 INCHES SEEM EASILY POSSIBLE ALONG/WEST OF A LINE FROM ROCHESTER
MN TO OELWEIN IA. FARTHER EAST...WITH PRECIPITATION TAKING LONGER TO
SPREAD IN...MUCH LIGHTER AMOUNTS ARE ANTICIPATED...ESPECIALLY IN THE
DRIER AIR NORTHEAST OF I-94.
MONDAY NIGHT AND TUESDAY IS A LITTLE MORE PROBLEMATIC BECAUSE MODELS
HAVE STRUGGLED WITH THE POTENT UPPER TROUGH. EVEN TODAY...THERE ARE
QUESTIONS ON HOW MUCH EASTERLY MOVEMENT THE CORE OF THE UPPER TROUGH
WILL HAVE AS IT COMES OUT OF THE DAKOTAS. THE 03.00Z/06Z NAM REMAIN
THE FARTHEST EAST...TRACKING ACROSS CENTRAL/EASTERN IOWA TUESDAY
MORNING. ON THE OTHER END OF THE SPECTRUM IS THE 03.00Z UKMET...
DROPPING INTO NORTHEAST KANSAS AT THE SAME TIME. THE 03.00Z
GFS/CANADIAN/ECMWF ARE IN THE MIDDLE...TRACKING ACROSS FAR WESTERN
IOWA INTO NORTHWEST MISSOURI. OVERALL...THERE HAS BEEN A SHIFT EAST
WITH THE TRACK OVER THE PAST FEW MODEL RUNS...PUTTING MORE OF THE
FORECAST AREA INTO PRECIPITATION. AS SUCH...HAVE INCREASED AND
EXPANDED PRECIPITATION CHANCES FARTHER EAST. THE SETUP FOR MONDAY
NIGHT AND TUESDAY LOOKS MORE IMPRESSIVE DUE TO STRONGER DPVA FORCING
THE UPPER TROUGH. A NICE TROWAL SHOULD DEVELOP AS WELL ON THE
NORTHEAST SIDE OF THE UPPER TROUGH. ON TOP OF THIS...THE UPPER LOW
BRINGS IN COLDER AIR...POTENTIALLY RESULTING IN A DEEPER DENDRITIC
GROWTH ZONE. IN ANY EVENT...THE COLDER WILL CAUSE SNOW RATIOS TO
INCREASE. FOR BOTH QPF AND SNOW RATIOS...TOOK A MODEL CONSENSUS...
WHICH YIELDS ABOUT 6 TO 8 INCHES OF SNOWFALL SOUTHWEST OF I-94 OVER
THE MONDAY NIGHT AND TUESDAY PERIOD. THESE COULD EASILY BE HIGHER...
AS WELL AS EITHER SHIFTED EAST OR WEST DEPENDING ON THE EXACT UPPER
LOW TRACK.
REGARDING HAZARDS...WITH THE SHIFT EAST IN THE MONDAY NIGHT/TUESDAY
PERIOD...AN EXPANSION OF THE WATCH IS REQUIRED TO INCLUDE FROM
BUFFALO COUNTY SOUTHEAST TO GRANT COUNTY WI. CONVERTING THE EXISTING
WATCH TO WARNING OR ADVISORY ELSEWHERE IS VERY DIFFICULT AT THIS
TIME. ALTHOUGH MODELS AGREE WELL ON THE TONIGHT/MONDAY PERIOD...AT
MOST IT APPEARS A 12 HOUR PERIOD OF 3-5 INCHES WITH A 24 HOUR TOTAL
OF UP TO 6 INCHES...ALL BELOW WARNING CRITERIA. IMPACT WISE...THE
MORNING COMMUTE ACROSS SOUTHEAST MN AND NORTHEAST IOWA
DEFINITELY WILL BE AFFECTED...BUT THE SNOWFALL RATE RIGHT NOW DOES
NOT LOOK HIGH ENOUGH TO JUSTIFY A WARNING. OVER THE COURSE OF THE
ENTIRE PERIOD THROUGH TUESDAY...LOCATIONS ACROSS SOUTHEAST MINNESOTA
INTO NORTHEAST IOWA COULD PICK UP UPWARDS OF 10-15 INCHES...BUT THIS
IS OVER A 42 HOUR TIMEFRAME...WHICH MEANS SOME MELTING/SETTLING WILL
OCCUR. IN ADDITION...THE MONDAY NIGHT/TUESDAY PERIOD HAS GOT A LOT
OF UNCERTAINTY WITH THE UPPER TROUGH TRACK. THUS...AFTER
COLLABORATION WITH MPX...DMX AND DVN...HAVE LEFT THE WATCH INTACT
FOR NOW. CONVERSIONS TO WARNINGS AND/OR ADVISORIES WILL LIKELY TAKE
PLACE DURING THE DAY.
PRECIPITATION LOOKS TO TAIL OFF PRETTY QUICK TUESDAY NIGHT AS THE
UPPER TROUGH HEADS OFF TO THE MID-ATLANTIC REGION. DID PUT A 20
PERCENT CHANCE IN FOR THE EVENING ACROSS MUCH OF THE AREA WITH
SUGGESTIONS THE COLD CONVEYOR BELT MAY STILL BE AFFECTING US.
.LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT
325 AM CST SUN MAR 3 2013
AFTER AN ACTIVE SHORT TERM PERIOD...THE LONG TERM LOOKS MAINLY QUIET
WITH A PATTERN SHIFT STILL PROGGED TO OCCUR. A DEEP TROUGH IS
PROGGED TO MOVE INTO THE WESTERN U.S. WEDNESDAY INTO THURSDAY...
CAUSING RIDGING TO SHIFT EAST AND BUILD DOWNSTREAM TOWARDS THE
FORECAST AREA. SUBSIDENCE UNDER THE UPPER RIDGE COMBINED WITH HIGH
PRESSURE COMING THROUGH AT THE SURFACE WILL YIELD DRY AND LIKELY
MOSTLY SUNNY DAYS. 850MB TEMPS WARM AS WELL...ALLOWING HIGHS TO
CLIMB BACK TO NORMAL LEVELS BY THURSDAY.
FOR THURSDAY NIGHT AND HEADING INTO THE WEEKEND...THE WESTERN TROUGH
LOOKS TO SPLIT INTO TWO...WITH THE BULK OF IT CLOSING OFF INTO AN
UPPER LOW IN THE DESERT SOUTHWEST. THE NORTHERN STREAM PORTION OF
THIS TROUGH IS FORECAST TO HEAD UP INTO NORTHERN ONTARIO ON
FRIDAY...BRINGING A WEAKENING COLD FRONT THROUGH THE AREA. FOLLOWED
THE CONSENSUS WHICH HAD A 20 PERCENT CHANCE UP IN NORTHERN WISCONSIN
FOR FRIDAY. 20 PERCENT CHANCES ARE ALSO IN THE FORECAST FOR FRIDAY
NIGHT EVERYWHERE...ASSOCIATED WITH POSSIBLE WEAK FRONTOGENESIS IN
THE WAKE OF THE FRONTAL PASSAGE. DRIER WEATHER FOLLOWS FOR
SATURDAY...THOUGH THE LATEST 03.00Z ECMWF TRIES TO MAINTAIN THE
FRONTOGENESIS AND LIGHT PRECIPITATION. THUS...LATER FORECASTS MAY
NEED TO ADD SOME CHANCES IN FOR SATURDAY. TEMPERATURES BOTH FRIDAY
AND SATURDAY SHOULD END UP AT OR ABOVE NORMAL...EVEN WITH THE
PASSAGE OF THE WEAK COLD FRONT SINCE PACIFIC AIR IS FLOWING IN
BEHIND IT.
&&
.AVIATION...TODAY AND TONIGHT
530 AM CST SUN MAR 3 2013
BROKEN ALTOSTRATUS WILL MOVE ACROSS THE TAF SITES TODAY WITH CLOUD
BASES IN THE 6 TO 10 KFT RANGE. CEILINGS ARE EXPECTED TO LOWER
TONIGHT AS A STRONG LOW PRESSURE SYSTEM APPROACHES FROM THE
NORTHERN PLAINS. PLAN ON CEILINGS LOWERING TO 2500 FT AT KRST
AROUND 5 Z AT KRST AND AROUND 11Z AT KLSE. LIGHT SNOW WILL DEVELOP
AT KRST IN THE 10 TO 12Z TIMEFRAME WITH CEILINGS LOWERING TO 2SM
AND CEILINGS FALLING TO 700 FT. THE SNOW WILL SPREAD EAST AND
IMPACT KLSE AFTER 12Z MONDAY. A LONG PERIOD OF SNOW WILL OCCUR AT
THE TAF SITES MONDAY INTO TUESDAY WITH PERIODS OF IFR/LIFR
CONDITIONS EXPECTED. PLAN ON WINDS INCREASING OUT OF THE SOUTHEAST
LATE TONIGHT INTO MONDAY MORNING AS THE LOW DRAWS CLOSER. SOME
BLOWING SNOW COULD IMPACT KRST DURING THE DAY ON MONDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
325 AM CST SUN MAR 3 2013
WI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR WIZ032-033-041-053>055-061.
MN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR MNZ079-086-087-094-095.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR MNZ088-096.
IA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR IAZ008-009-018-019.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR IAZ010-011-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 AM CST SUN MAR 3 2013
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
325 AM CST SUN MAR 3 2013
MAIN FOCUS IS ON THE LONG PERIOD OF ACCUMULATING SNOW LATE TONIGHT
THROUGH TUESDAY
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT
ANALYSIS SHOWED A POTENT SHORTWAVE TROUGH OVER SOUTHERN BRITISH
COLUMBIA INTO WASHINGTON STATE...RIDGING FROM BAJA CALIFORNIA INTO
SOUTHERN SASKATCHEWAN...AND A SHORTWAVE TROUGH DROPPING INTO EASTERN
WISCONSIN. PLENTIFUL UPPER LEVEL MOISTURE WAS STREAMING NORTH OUT OF
THE TROPICAL EAST PACIFIC AND THROUGH THE TOP OF THE UPPER RIDGE...
MANIFESTING ITSELF AS CIRRUS CLOUD COVER OVER THE DAKOTAS INTO
WESTERN MINNESOTA. EAST OF THIS CIRRUS...AN ALTOSTRATUS DECK WAS
PRESENT ACROSS MUCH OF MINNESOTA AND IOWA. THIS DECK IS A RESULT OF
RELATIVELY HIGHER MOISTURE OVER THE DAKOTAS GETTING ISENTROPICALLY
LIFTED. 00Z SOUNDING DATA SHOWED PRECIPITABLE WATER OF 0.16 INCHES
AT MPX...OR 66 PERCENT OF NORMAL...COMPARED TO 0.4 INCHES AT BIS AND
ABR OR 175 PERCENT OF NORMAL. BIG 850MB TEMPERATURE DIFFERENCE
TOO...WITH MPX AT -8C COMPARED TO AROUND 3C AT BIS AND ABR. DESPITE
THE PRESENCE OF THE ALTOSTRATUS DECK AND SOME LIGHT RETURNS ON
REGIONAL RADAR...NOTHING HAS REACHED THE SURFACE DUE TO DRIER LOW
LEVEL AIR SEEN ON THAT 00Z MPX SOUNDING. DRY AIR SEEN ON THE 00Z GRB
SOUNDING HAS ALSO PREVENTED MUCH FOR CLOUDS WITH THE SHORTWAVE
DROPPING THROUGH EASTERN WISCONSIN. AT THE SURFACE...A RIDGE OF HIGH
PRESSURE ENCOMPASSED MUCH OF THE WESTERN GREAT LAKES WHILE LOW
PRESSURE WAS DEEPENING IN SOUTHERN ALBERTA. LASTLY...REGARDING THAT
POTENT SHORTWAVE TROUGH...00Z RAOB DATA SHOWED SOME PRETTY
IMPRESSIVE 500MB HEIGHT FALLS...AROUND 100 METERS IN 12 HOURS.
ALL MODELS CONTINUE TO INDICATE THAT THE LONG PERIOD OF SNOW WILL
OCCUR FROM THE NORTHERN PLAINS SOUTHEAST INTO PORTIONS OF THE
FORECAST AREA. THREE DISTINCT FORCING MECHANISMS ARE GOING TO GOVERN
THIS SNOW...WITH THE LAST TWO ITEMS MODULATING THE INTENSITY AND
PLACEMENT...
1. A LOW TO MID LEVEL FRONTOGENESIS ZONE...WHICH CAN ALREADY BE SEEN
IN THE 00Z SOUNDING DATA NOTED BY THE SHARP DIFFERENCE IN 850MB
TEMPS BETWEEN MPX AND ABR.
2. A HARD TO SEE SHORTWAVE ON WATER VAPOR CURRENTLY IN SOUTHERN
IDAHO PROGGED TO MOVE WEST TO EAST THROUGH THE FORECAST AREA ON
MONDAY
3. THE POTENT UPPER TROUGH WHICH DROPS SOUTHEAST OUT OF THE NORTHERN
PLAINS ON MONDAY AND INTO THE MID-MISSISSIPPI VALLEY BY LATE TUESDAY
OVERALL...MODELS AGREE REALLY WELL TONIGHT INTO MONDAY IN THE
HANDLING OF THE FRONTOGENESIS ZONE AND SHORTWAVE MOVING THROUGH.
BETWEEN 00-06Z TONIGHT...SOUTH WINDS REALLY PICK UP ON THE 285-290K
SURFACES IN SOUTHWEST MINNESOTA AHEAD OF THE APPROACHING
SHORTWAVE...HELPING TO INCREASE THE INTENSITY OF THE FRONTOGENESIS
ZONE. COMBINED WITH PACIFIC MOISTURE ALREADY PRESENT IN THE
DAKOTAS...SNOW SHOULD EASILY BREAK OUT. AS THE SHORTWAVE PRESSES
EAST TOWARDS THE AREA AFTER 06Z...THE FRONTOGENESIS ZONE SHIFTS EAST
WITH IT...IMPACTING LOCATIONS WEST OF THE MISSISSIPPI RIVER. HIGHER
HORIZONTAL RESOLUTION QPF DATA FROM THE 03.00Z NAM...HIRES-ARW/NMM
AND REGIONAL CANADIAN SUGGEST ANYWHERE FROM 0.25-0.30...HIGHEST IN
THE AUSTIN/CHARLES CITY AREA. EVEN HIGHER AMOUNTS LOOK POSSIBLE TO
THE NORTHWEST. SOUNDINGS DEPICT ONLY A 75MB LAYER OF DENDRITIC
GROWTH...WAY UP AROUND 600MB...WITH LIFT THROUGHOUT A LOT OF THE
COLUMN. THUS...THINKING SNOW TO WATER RATIOS SHOULD STAY AROUND 10
TO 1...YIELDING UPWARDS OF 2-3 INCHES BY 12Z. THE FRONTOGENESIS ZONE
CONTINUES TO PUSH EAST DURING THE DAY MONDAY BY THE SHORTWAVE...
EVENTUALLY STALLING OUT OVER THE SOUTHWEST 2/3 OF THE FORECAST AREA
FOR THE AFTERNOON. THE HEAVIEST PRECIPITATION LOOKS TO OCCUR IN THE
MORNING WITH ENHANCEMENT FROM THE SHORTWAVE BEFORE THE SHORTWAVE
LIFTS OFF. COULD SEE UPWARDS OF 0.25 INCH DURING THE MORNING IN
SOUTHEAST MN INTO PORTIONS OF NORTHEAST IOWA...EQUATING TO ANOTHER
2-3 INCHES OF SNOW. THUS...FOR THE 06-18Z MONDAY PERIOD...TOTALS OF
4-5 INCHES SEEM EASILY POSSIBLE ALONG/WEST OF A LINE FROM ROCHESTER
MN TO OELWEIN IA. FARTHER EAST...WITH PRECIPITATION TAKING LONGER TO
SPREAD IN...MUCH LIGHTER AMOUNTS ARE ANTICIPATED...ESPECIALLY IN THE
DRIER AIR NORTHEAST OF I-94.
MONDAY NIGHT AND TUESDAY IS A LITTLE MORE PROBLEMATIC BECAUSE MODELS
HAVE STRUGGLED WITH THE POTENT UPPER TROUGH. EVEN TODAY...THERE ARE
QUESTIONS ON HOW MUCH EASTERLY MOVEMENT THE CORE OF THE UPPER TROUGH
WILL HAVE AS IT COMES OUT OF THE DAKOTAS. THE 03.00Z/06Z NAM REMAIN
THE FARTHEST EAST...TRACKING ACROSS CENTRAL/EASTERN IOWA TUESDAY
MORNING. ON THE OTHER END OF THE SPECTRUM IS THE 03.00Z UKMET...
DROPPING INTO NORTHEAST KANSAS AT THE SAME TIME. THE 03.00Z
GFS/CANADIAN/ECMWF ARE IN THE MIDDLE...TRACKING ACROSS FAR WESTERN
IOWA INTO NORTHWEST MISSOURI. OVERALL...THERE HAS BEEN A SHIFT EAST
WITH THE TRACK OVER THE PAST FEW MODEL RUNS...PUTTING MORE OF THE
FORECAST AREA INTO PRECIPITATION. AS SUCH...HAVE INCREASED AND
EXPANDED PRECIPITATION CHANCES FARTHER EAST. THE SETUP FOR MONDAY
NIGHT AND TUESDAY LOOKS MORE IMPRESSIVE DUE TO STRONGER DPVA FORCING
THE UPPER TROUGH. A NICE TROWAL SHOULD DEVELOP AS WELL ON THE
NORTHEAST SIDE OF THE UPPER TROUGH. ON TOP OF THIS...THE UPPER LOW
BRINGS IN COLDER AIR...POTENTIALLY RESULTING IN A DEEPER DENDRITIC
GROWTH ZONE. IN ANY EVENT...THE COLDER WILL CAUSE SNOW RATIOS TO
INCREASE. FOR BOTH QPF AND SNOW RATIOS...TOOK A MODEL CONSENSUS...
WHICH YIELDS ABOUT 6 TO 8 INCHES OF SNOWFALL SOUTHWEST OF I-94 OVER
THE MONDAY NIGHT AND TUESDAY PERIOD. THESE COULD EASILY BE HIGHER...
AS WELL AS EITHER SHIFTED EAST OR WEST DEPENDING ON THE EXACT UPPER
LOW TRACK.
REGARDING HAZARDS...WITH THE SHIFT EAST IN THE MONDAY NIGHT/TUESDAY
PERIOD...AN EXPANSION OF THE WATCH IS REQUIRED TO INCLUDE FROM
BUFFALO COUNTY SOUTHEAST TO GRANT COUNTY WI. CONVERTING THE EXISTING
WATCH TO WARNING OR ADVISORY ELSEWHERE IS VERY DIFFICULT AT THIS
TIME. ALTHOUGH MODELS AGREE WELL ON THE TONIGHT/MONDAY PERIOD...AT
MOST IT APPEARS A 12 HOUR PERIOD OF 3-5 INCHES WITH A 24 HOUR TOTAL
OF UP TO 6 INCHES...ALL BELOW WARNING CRITERIA. IMPACT WISE...THE
MORNING COMMUTE ACROSS SOUTHEAST MN AND NORTHEAST IOWA
DEFINITELY WILL BE AFFECTED...BUT THE SNOWFALL RATE RIGHT NOW DOES
NOT LOOK HIGH ENOUGH TO JUSTIFY A WARNING. OVER THE COURSE OF THE
ENTIRE PERIOD THROUGH TUESDAY...LOCATIONS ACROSS SOUTHEAST MINNESOTA
INTO NORTHEAST IOWA COULD PICK UP UPWARDS OF 10-15 INCHES...BUT THIS
IS OVER A 42 HOUR TIMEFRAME...WHICH MEANS SOME MELTING/SETTLING WILL
OCCUR. IN ADDITION...THE MONDAY NIGHT/TUESDAY PERIOD HAS GOT A LOT
OF UNCERTAINTY WITH THE UPPER TROUGH TRACK. THUS...AFTER
COLLABORATION WITH MPX...DMX AND DVN...HAVE LEFT THE WATCH INTACT
FOR NOW. CONVERSIONS TO WARNINGS AND/OR ADVISORIES WILL LIKELY TAKE
PLACE DURING THE DAY.
PRECIPITATION LOOKS TO TAIL OFF PRETTY QUICK TUESDAY NIGHT AS THE
UPPER TROUGH HEADS OFF TO THE MID-ATLANTIC REGION. DID PUT A 20
PERCENT CHANCE IN FOR THE EVENING ACROSS MUCH OF THE AREA WITH
SUGGESTIONS THE COLD CONVEYOR BELT MAY STILL BE AFFECTING US.
.LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT
325 AM CST SUN MAR 3 2013
AFTER AN ACTIVE SHORT TERM PERIOD...THE LONG TERM LOOKS MAINLY QUIET
WITH A PATTERN SHIFT STILL PROGGED TO OCCUR. A DEEP TROUGH IS
PROGGED TO MOVE INTO THE WESTERN U.S. WEDNESDAY INTO THURSDAY...
CAUSING RIDGING TO SHIFT EAST AND BUILD DOWNSTREAM TOWARDS THE
FORECAST AREA. SUBSIDENCE UNDER THE UPPER RIDGE COMBINED WITH HIGH
PRESSURE COMING THROUGH AT THE SURFACE WILL YIELD DRY AND LIKELY
MOSTLY SUNNY DAYS. 850MB TEMPS WARM AS WELL...ALLOWING HIGHS TO
CLIMB BACK TO NORMAL LEVELS BY THURSDAY.
FOR THURSDAY NIGHT AND HEADING INTO THE WEEKEND...THE WESTERN TROUGH
LOOKS TO SPLIT INTO TWO...WITH THE BULK OF IT CLOSING OFF INTO AN
UPPER LOW IN THE DESERT SOUTHWEST. THE NORTHERN STREAM PORTION OF
THIS TROUGH IS FORECAST TO HEAD UP INTO NORTHERN ONTARIO ON
FRIDAY...BRINGING A WEAKENING COLD FRONT THROUGH THE AREA. FOLLOWED
THE CONSENSUS WHICH HAD A 20 PERCENT CHANCE UP IN NORTHERN WISCONSIN
FOR FRIDAY. 20 PERCENT CHANCES ARE ALSO IN THE FORECAST FOR FRIDAY
NIGHT EVERYWHERE...ASSOCIATED WITH POSSIBLE WEAK FRONTOGENESIS IN
THE WAKE OF THE FRONTAL PASSAGE. DRIER WEATHER FOLLOWS FOR
SATURDAY...THOUGH THE LATEST 03.00Z ECMWF TRIES TO MAINTAIN THE
FRONTOGENESIS AND LIGHT PRECIPITATION. THUS...LATER FORECASTS MAY
NEED TO ADD SOME CHANCES IN FOR SATURDAY. TEMPERATURES BOTH FRIDAY
AND SATURDAY SHOULD END UP AT OR ABOVE NORMAL...EVEN WITH THE
PASSAGE OF THE WEAK COLD FRONT SINCE PACIFIC AIR IS FLOWING IN
BEHIND IT.
&&
.AVIATION...
1100 PM CST SAT MAR 2 2013
MID LEVEL CLOUDS WILL SHIFT WEST TO EAST ACROSS THE REGION
TONIGHT...MOSTLY 6-8 KFT...ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE.
NO -SN IS EXPECTED. LIGHT WIND FIELD AS A SFC HIGH MOVES ACROSS THE
UPPER MISSISSIPPI RIVER VALLEY. SOME BR FORMED IN THIS RIDGE LAST
NIGHT...BUT THE CLOUDS AND SIZABLE T/TD SHOULD KEEP THOSE CHANCES AT
BAY. WINDS WILL BECOME SOUTHEASTERLY ON SUNDAY AS THE HIGH MOVES
TOWARD THE EASTERN GREAT LAKES. OVERALL...VFR CONDITIONS ARE
EXPECTED TONIGHT/SUNDAY.
A WINTER STORM WILL IMPACT THE REGION STARTING LATE SUNDAY
NIGHT...PERSISTING INTO TUE. A PROLONGED PERIOD OF VSBY RESTRICTING
-SN IS LOOKING PROBABLE...WITH THE POSSIBILITY OF SIGNIFICANT
ACCUMULATIONS - ESPECIALLY KRST. MVFR CIGS WILL PROBABLY HOLD OFF
UNTIL AFTER 12Z MON. ITS A STORM TO BE WATCHED AS IT WILL IMPACT
AVIATION INTERESTS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
325 AM CST SUN MAR 3 2013
WI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR WIZ032-033-041-053>055-061.
MN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR MNZ079-086-087-094-095.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR MNZ088-096.
IA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR IAZ008-009-018-019.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR IAZ010-011-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
433 AM MST SUN MAR 3 2013
.AVIATION...12Z TAFS
LOOK FOR LOWERING CLOUD BASES TODAY AS A COLD FRONT APPROACHES THE
AREA FROM THE NORTHWEST. LOW END MVFR LOOKS LIKELY AT KRWL THIS
AFTERNOON WITH LATEST HRRR MODEL EVEN FORECASTING THE CHANCE FOR
IFR CONDITIONS. FOR NOW...CONTINUED 1500 FOOT CEILINGS AT KRWL.
MORNING SHIFT WILL NEED TO MONITOR TRENDS FOR THE 18Z TAFS.
OTHERWISE...VFR EXPECTED WITH GUSRY WEST WINDS.
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 321 AM MST SUN MAR 3 2013/
SHORT TERM...TODAY THROUGH TUESDAY...THE PRIMARY FORECAST CONCERN
IN THE SHORT TERM IS THE PACIFIC STORM SYSTEM AND ASSOCIATED COLD
FRONT FORECAST TO PUSH ACROSS WYOMING LATER TODAY AND TONIGHT.
THIS SYSTEM IS NOT EXPECTED TO PRODUCE MUCH PRECIPITATION FOR THE
LOWER ELEVATIONS OF SOUTHEAST WYOMING AND WESTERN NEBRASKA...BUT
WINDS WILL BE THE MAIN CONCERN THROUGH MONDAY. WEST TO SOUTHWEST
WINDS HAVE INCREASED EARLY THIS MORNING WITH THE ARLINGTON AREA
REPORTING GUSTS BETWEEN 50 TO 55 MPH...AND GUSTS BETWEEN 30 TO 40
MPH ELSEWHERE. WINDS NOT AS STRONG COMPARED TO WHAT WAS EXPECTED
24 HOURS AGO...BUT WILL KEEP THE HIGH WIND WARNING GOING FOR THE
WIND PRONE ZONES THROUGH TODAY. BASED ON 00Z MODELS...LOOKS LIKE
THE GRADIENT WILL DECREASE TONIGHT INSTEAD OF MONDAY MORNING...SO
THE WARNING MAY NEED TO BE CANCELLED EARLY. OTHERWISE...WESTERLY
WINDS WILL INCREASE OVER THE REST OF THE FORECAST AREA THIS
AFTERNOON DUE TO GOOD BOUNDARY LAYER MIXING. EXPECT WINDS TO STAY
BELOW HIGH WIND CRITERIA TODAY.
THE STRONG COLD FRONT WILL PUSH INTO SOUTHERN WYOMING TODAY.
ALTHOUGH DOWNSLOPE WINDS WILL RESULT IN MAINLY DRY WEATHER EAST OF
THE LARAMIE RANGE...MODELS SHOW GOOD UPSLOPE FLOW AND LLVL LIFT
ACROSS THE SIERRA MADRE RANGE AND SNOWY RANGE TODAY AND TONIGHT.
ISSUED A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW
BEGINNING NOON TODAY THROUGH NOON MONDAY FOR THESE AREAS. EXPECT 6
TO 12 INCHES OF SNOW WITH MOST OF THE SNOW FALLING THIS AFTERNOON
THROUGH LATE THIS EVENING. ALTHOUGH 6 TO 8 INCH AMOUNTS ARE
EXPECTED TO BE WIDESPREAD...CAN NOT RULE OUT LOCALLY HIGHER
ACCUMULATIONS DUE TO LLVL INSTABILITY.
FOR MONDAY...UPPER LEVEL TROUGH WILL PUSH INTO THE WESTERN DAKOTAS
AS THE COLD FRONT SWINGS THROUGH THE REST OF THE FORECAST AREA
INTO COLORADO AND KANSAS. MUCH COLDER TEMPERATURES ARE EXPECTED ON
MONDAY WITH HIGHS IN THE 20S AND 30S ACROSS SOUTHEAST
WYOMING...AND AROUND 40 ACROSS WESTERN NEBRASKA EARLY IN THE
MORNING. THE MAIN CONCERN WILL BE STRONG WEST TO NORTHWEST WINDS.
GFS MOS SHOWS WINDS OVER 40 KNOTS SUSTAINED ACROSS WESTERN
NEBRASKA MONDAY AFTERNOON AFTER THE FRONT PUSHES ACROSS THE AREA.
HOWEVER...DID NOT ISSUE A HIGH WIND WATCH FOR WESTERN NEBRASKA
SINCE CONFIDENCE IS NOT THAT HIGH FOR WIND GUSTS OVER 58 MPH.
ALTHOUGH THERE IS A STRONG LLVL PRESSURE GRADIENT AND MODELS SHOW
WINDS AROUND 45 KNOTS AT 700 MB...THE SURFACE FRONT PUSHES ACROSS
THE AREA TOO EARLY AS THE RIGHT EXIT REGION OF THE JET DOES NOT
ENTER THE AREA UNTIL LATE MONDAY NIGHT. MODEL OMEGA SHOWS PEAK
SUBSIDENCE AND DOWNSLOPE AFTER 00Z TUESDAY ACROSS WESTERN NEBRASKA
WITH LITTLE SUBSIDENCE BEFORE 00Z. AT THIS TIME...A WIND ADVISORY
LOOKS MORE LIKELY FOR GUSTS AROUND 50 MPH. OTHERWISE...ANY LIGHT
SNOW SHOWERS OR FLURRIES WILL DISSIPATE MONDAY NIGHT ALONG WITH
SLOWLY DIMINISHING WINDS. THIS WILL LEAD TO COLD OVERNIGHT LOWS IN
THE SINGLE DIGITS AND TEENS DUE TO A VERY DRY AIRMASS OVER THE
FORECAST AREA. A SLOW WARMING TREND WILL BEGIN ON TUESDAY WITH
HIGH TEMPERATURES RETURNING TO THE 30S (WEST) AND 40S (EAST).
LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
FORECAST CHALLENGE IN THE LONG TERM DEAL WITH PRECIP CHANCES NEXT
WEEKEND.
UPPER RIDGE LOOKS TO PASS OVER THE CWFA TUESDAY EVENING WITH
WARMING 700MB TEMPERATURES. GFS SHOWING +2C 700MB TEMPERATURES
INTO THE SOUTHERN NEBRASKA PANHANDLE WITH THE 0C LINE COVERING
MUCH OF SOUTHEAST WYOMING. LOOK FOR TEMPERATURES TO WARM BACK INTO
THE 60S ACROSS THE PANHANDLE WITH MID 40S WEST OF THE LARAMIE RANGE.
THESE WARM TEMPERATURES STAY WITH US THROUGH MUCH OF THE WEEK AS
700MB TEMPERATURES STAY FROM 0 TO +2C. ADDITIONALLY...WE ARE
LOOKING AT WINDY CONDITIONS AND DOWN SLOPING WESTERLY TO
SOUTHWESTERLY WINDS THAT WILL ADD TO THE WARM TEMPERATURES THROUGH
THURSDAY. LOOK FOR DAILY HIGHS SIMILAR TO WEDNESDAY WITH 60S IN
THE PANHANDLE AND 40S WEST OF THE LARAMIE RANGE.
THE WEATHER BEGINS TO CHANGE THURSDAY NIGHT INTO FRIDAY.
INITIALLY...FRONTAL PLACEMENT ON THE GFS AND ECMWF PRETTY
CONSISTENT...SHOWING A FRONT OVER NORTHWEST WYOMING...EXTENDING
SOUTHWEST INTO NEVADA. GFS CLOSES OFF AN UPPER LOW OVER SOUTHERN
NEVADA DURING THE DAY FRIDAY...WHILE THE ECMWF IS A LITTLE
SLOWER. GFS SHOWS A 1033MB SURFACE HIGH OVER EASTERN NORTH DAKOTA
PUSHING A BACKDOOR FRONTAL BOUNDARY INTO WESTERN SOUTH DAKOTA.
SHOULD BE SEEING SIGNIFICANT UPSLOPING DEVELOPING OVER THE
PANHANDLE AND EAST SLOPES OF THE LARAMIE RANGE DURING THIS TIME FRAME.
THE GFS TAKES THE UPPER LOW AND KEEPS IT SOUTH ACROSS ARIZONA AND
NEW MEXICO FOR SATURDAY. THE ECMWF ON THE OTHER HAND...EJECTS THE
LOW NORTHEASTWARD INTO WESTERN COLORADO WITH A SIGNIFICANT PRECIP
SHIELD DEVELOPING OVER MUCH OF THE CHEYENNE CWFA. SHOULD THE ECMWF
SOLUTION COME TRUE...WE ARE LOOKING AT A SIGNIFICANT WINTER
WEATHER EVENT AS QPFS ARE WELL OVER AN INCH. SHOULD THE GFS
SOLUTION COME TRUE...WE MAY MISS OUT ON PRECIP ALTOGETHER AS IT
PLACES ALL THE QPF OVER COLORADO.
WENT AHEAD AND INCREASED POPS TO SLIGHT CHANCE FOR MOST AREAS WITH
CHANCE POPS IN THE SNOWY AND SIERRA MADRE RANGES. HOPEFULLY OVER
THE NEXT COUPLE MODEL RUNS...WE CAN GET A LITTLE MORE CONSISTENCY
BETWEEN THE GFS AND ECMWF. ONE OTHER NOTE THOUGH...THE ECMWF HAS
BEEN SHOWING THIS NOW THE PAST 3-4 MODEL RUNS...SO WE WILL NEED TO
KEEP AN EYE ON THIS STORM DEVELOPING.
&&
FIRE WEATHER...STRONG WINDS ARE EXPECTED OVER MOST OF SOUTHEAST
WYOMING AND WESTERN NEBRASKA TODAY AND MONDAY AS A STRONG COLD
FRONT PUSHES ACROSS THE REGION. THESE WINDS WILL BECOME MORE
WIDESPREAD ON MONDAY AFTER THE FRONT PUSHES ACROSS THE AREA.
DOWNSLOPE WINDS WILL RESULT IN A DRY BOUNDARY LAYER WITH MINIMUM
HUMIDITIES LOWERING INTO THE 20S BY MONDAY AND TUESDAY AFTERNOON.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING UNTIL NOON MONDAY FOR WYZ106-WYZ110-WYZ116-
WYZ117.
WINTER WEATHER ADVISORY FROM NOON SUNDAY TO NOON MONDAY FOR
WYZ112-WYZ114.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...TJT
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
306 AM CST TUE MAR 5 2013
.DISCUSSION...
753 PM CST
MADE A FEW MINOR ADJUSTMENTS TO THE FORECAST OVERNIGHT REGARDING
THE ONSET OF PRECIP. SCATTERED LIGHT SNOW SHOWERS ARE ACROSS
MINNESOTA...WISCONSIN...AND IOWA AHEAD OF THE LOW PRESSURE SYSTEM.
WITH SLIGHTLY DRIER AIR OVER NORTHERN IL...NOT EXPECTING MUCH
SNOWFALL FROM THESE SNOW SHOWERS AS THEY MOVE INTO OUR AREA. IN
FACT NUMEROUS AREAS UNDER THE REFLECTIVITIES TO OUR WEST ARE NOT
REPORTING ANY PRECIP AT THE SFC. REDUCED POPS TO SLIGHT CHANCE
THROUGH MIDNIGHT WITH LITTLE TO NO SNOW EXPECTED.
THE SYSTEM IS MOVING A LITTLE SLOWER THAN EARLIER THOUGHT SO ALSO
LOWERED POPS BTWN MIDNIGHT AND 3AM TO CHANCE OR LESS. HRRR AND OUR
IN HOUSE ARW BOTH INDICATE SNOW WILL NOT REACH CENTRAL IL UNTIL
LATE TONIGHT AFTER 3AM. DID NOT GO AS SLOW AS THEY INDICATED AS
THE ATMOSPHERE COULD BECOME MORE SATURATED BY LIGHT FLURRIES
OVERNIGHT.
OTHERWISE THE GOING FORECAST LOOKS ON TRACK WITH THE HEAVIEST
SNOWFALL STILL EXPECTED FROM TOMORROW MORNING THROUGH THE EVENING
HOURS. NO CHANGES WERE MADE TO THE WINTER STORM WARNING. TRAVEL
WILL BE SEVERELY IMPACTED BY SNOWFALL RATES OF 1-2 INCHES PER HOUR
AND LOW VISIBILITIES. WINDS INCREASE TOMORROW EVENING AND BLOWING
SNOW TUESDAY EVENING AND OVERNIGHT WILL LIKELY REDUCE VISIBILITIES
TO A QUARTER MILE OR LESS AT TIMES.
JEE
//PREV DISCUSSION...
315 PM CST
SHORT RANGE...TONIGHT THROUGH TUESDAY NIGHT...
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE REST OF MY
COUNTIES FOR LATE TONIGHT THROUGH TUESDAY EVENING.
NOT MUCH HAS CHANGED FROM THE PREVIOUS THINKING. THE LATEST WATER
VAPOR IMAGERY PLACES THE CENTER OF THIS SYSTEM ACROSS THE DAKOTAS
THIS AFTERNOON. WARM AIR ADVECTION/ISENTROPIC ASCENT AHEAD OF THIS
FEATURE HAS LEAD TO A WEAK BAND OF MAINLY LIGHT SNOW AND FLURRIES
ACROSS THE AREA THIS AFTERNOON. THIS HAS NOT AMOUNTED TO MUCH AND
LIKELY WILL NOT THROUGH THIS EVENING. THE MAIN SHOW WILL GET GOING
LATE TONIGHT AND ON TUESDAY. THE GUIDANCE HAS DISAGREEMENTS ON THE
EXACT TIMING OF THE ONSET OF PRECIP...WITH THE ECMWF AND NAM
SUGGESTING THAT THE SNOW MAY HOLD OFF UNTIL DAYBREAK. I DID BACK
OFF ON POPS A BIT TONIGHT TO ACCOUNT FOR A LATER ONSET...BUT STILL
MENTION LIKELY POPS TOWARDS DAYBREAK.
ONCE THINGS GET GOING TUESDAY MORNING...IT APPEARS THE SNOW INCREASE
IN INTENSITY THROUGH THE LATE MORNING AND DURING THE AFTERNOON.
IMPRESSIVE FORCING FOR ASCENT IS PROGGED TO SET UP IN THE DENDRITIC
GROWTH ZONE DURING THE AFTERNOON AS ISENTROPIC ASCENT INCREASES
AHEAD THE APPROACHING MID LEVEL SYSTEM. IT ALSO APPEARS THAT A TROWAL
LIKE STRUCTURE WILL DEVELOP ACROSS THE REGION DURING THE AFTERNOON
AS THE 700 MB LOW TRACKS SOUTHEASTWARD FROM EASTERN IOWA AND ACROSS
CENTRAL ILLINOIS. THIS WILL LIKELY LEAD TO A DECENT BAND OF MID
LEVEL FRONTOGENESIS FROM NORTH-NORTHWEST TO SOUTH-SOUTHEAST RIGHT
ACROSS THE CWA. AS IT TYPICAL WITH THIS TYPE OF SETUP...LOW STATIC
STABILITY SETS UP IN THE MID LEVELS DUE TO STEEP LAPSE RATES. LOOKS
TO SET UP THE INGREDIENTS FOR PERIODS OF HEAVY SNOW ACROSS THE AREA
DURING THE AFTERNOON WITH SNOW RATES OF 1 TO 1.5 INCHES AT TIMES.
I STILL DO HAVE SOME CONCERNS FOR PRECIPITATION TYPES ACROSS MY
SOUTHERN COUNTIES INITIALLY TUESDAY MORNING. GUIDANCE CONTINUES TO
SUGGEST THAT ENOUGH WARM AIR MAY BE SQUEEZED NORTHWARD ACROSS
CENTRAL ILLINOIS TO RESULT IN SOME RAIN OR SLEET AND SNOW MIX
THROUGH MID TO LATE MORNING. THEREAFTER...STRONG DYNAMIC COOLING
ASSOCIATED WITH MID LEVEL HEIGHT FALLS AND STRONG ASCENT...SHOULD
LEAD TO ALL SNOW DURING THE AFTERNOON. ALTHOUGH SNOW TO LIQUID
RATIOS MAY ONLY BE 10:1 FOR A PERIOD FAR SOUTH...IT APPEARS THAT
HEAVY SNOW COULD STILL RESULT IN 6 OR MORE INCHES ACROSS THESE
AREAS...AND THEREFORE HAVE INCLUDED THEM IN THE WARNING.
SOME OF THE GUIDANCE HAS SHIFTED THE HEAVIEST PRECIP AXIS JUST A TAD
SOUTH. HOWEVER...WITH LAKE ENHANCEMENT LIKELY TUESDAY AFTERNOON AND
EVENING...PERIODS OF HEAVY SNOW STILL APPEARS TO BE A GOOD BET
ACROSS FAR NORTHEAST ILLINOIS.
WINDS WILL INCREASE OUT OF THE NORTH-NORTHEAST LATE TUESDAY AFTERNOON
AND NIGHT AS THE LOW DEEPENS ACROSS THE OHIO VALLEY. THESE WINDS
COULD GUST UP TO 30-35 MPH...RESULTING IN SOME BLOWING AND DRIFTING
SNOW. I ADDED BLOWING SNOW AREA-WIDE BY TUESDAY EVENING TO ACCOUNT
FOR THIS.
SNOW SHOULD BEGIN TO TAPPER OFF FROM WEST TO EAST ACROSS THE AREA
DURING THE EVENING ON TUESDAY. HOWEVER...SOME MODERATE TO HEAVY SNOW
MAY CONTINUE INTO THE LATER EVENING HOURS...ESPECIALLY ACROSS
EASTERN ILLINOIS AND INTO INDIANA. HOWEVER...SNOWFALL RATES SHOULD
DROP OFF SIGNIFICANTLY AFTER 06 UTC ON WEDNESDAY...WITH ONLY SOME
LAKE EFFECT SNOW SHOWERS CONTINUING INTO WEDNESDAY.
KJB
LONGER RANGE...WEDNESDAY THROUGH NEXT MONDAY...
THE MAIN CONCERNS BEYOND THE EARLY WEEK WINTER STORM INCLUDE THE
POTENTIAL FOR SOME LINGERING LAKE EFFECT SNOW WEDNESDAY INTO EARLY
THURSDAY...THEN AFTER A COUPLE OF QUIET DAYS A WARM-UP WITH THE
POTENTIAL FOR RAIN ARRIVES LATER IN THE WEEKEND AND EARLY NEXT WEEK.
STRONG UPPER/SURFACE LOWS ASSOCIATED WITH THE DEPARTING WINTER STORM
SYSTEM SHOULD BE DIGGING WELL OFF TO OUR SOUTHEAST ACROSS THE
CENTRAL/SOUTHERN APPALACHIANS AND OFF THE MID-ATLANTIC COAST
WEDNESDAY. GUIDANCE DOES DEPICT A RAPIDLY SHEARING/WEAKENING
MID-LEVEL VORT MOVING ACROSS THE AREA DURING THE MORNING HOURS...
THOUGH OVERALL RISING HEIGHTS/DEVELOPING UPPER RIDGING IS INDICATED
WITH LOW LEVEL COLD ADVECTION AND DECREASING CYCLONIC CURVATURE.
THIS PRODUCES SUBSIDENCE AND DRYING ABOVE THE BOUNDARY LAYER... WITH
LITTLE/NO SYNOPTIC SCALE FORCING FOR LINGERING PRECIP. WITHIN THE
BOUNDARY LAYER HOWEVER...NORTH-NORTHEAST FLOW DOWN LAKE MICHIGAN
PRODUCES LONG FETCH AND FAIRLY STRONG MOISTURE-CONVERGENCE ALONG THE
WEST/SOUTHWEST SHORE. THERMODYNAMIC PROFILES BASED ON 12Z WRF-NAM
AND GFS SHOW RELATIVELY MARGINAL SETUP FOR ORGANIZED SNOW SHOWERS
HOWEVER...WITH 850 MB TEMPS ONLY AROUND -8/9C WEDNESDAY AND
WEDNESDAY NIGHT. THIS YIELDS WATER SFC TO 850 MB DELTA T VALUES
AROUND 12/13...WITH COMPUTED EQUILIBRIUM LEVELS LESS THAN 5000 FT
AGL. WHILE SUFFICIENT TO PRODUCE LAKE EFFECT CLOUDS AND LIGHT SNOW
SHOWERS...THESE PARAMETERS SUGGEST IT WOULD BE DIFFICULT TO GET ANY
SIGNIFICANT ACCUMULATION UNLESS SNOW BAND WERE STATIONARY FOR A LONG
PERIOD OF TIME. LOW LEVEL WIND PROFILES INDICATE THAT CONVERGENCE
WILL FAVOR THE ILLINOIS SHORE INTO LAKE COUNTY INDIANA THROUGH
WEDNESDAY EVENING...THUS HAVE INDICATED SOME MINOR ACCUMULATION OF A
FEW TENTHS OF AN INCH THERE. IF STRONGER THERMODYNAMICS WERE TO
OCCUR OR THE BAND WERE TO EXPERIENCE A HIGHER RESIDENCE TIME IN ANY
ONE LOCATION PERHAPS AN INCH OR TWO COULD ACCUMULATE...THOUGH
CONFIDENCE IN THAT OCCURRING IS VERY LOW. HIGH PRESSURE RIDGE
SPREADS EAST ACROSS THE MISSISSIPPI VALLEY LATER WEDNESDAY NIGHT AND
THURSDAY...WHICH LEADS TO WINDS WEAKENING AND VEERING NORTHEAST
THURSDAY MORNING AND THEN EAST LATER IN THE DAY WITH THERMODYNAMIC
SETUP ALSO WEAKENING RAPIDLY BEYOND THURSDAY MORNING.
PERIOD OF QUIET WEATHER IS THEN ANTICIPATED AS UPPER RIDGE BUILDS
ACROSS THE CENTRAL CONUS...AND SURFACE HIGH PRESSURE RIDGE MOVES
SLOWLY ACROSS THE AREA INTO FRIDAY. TEMPERATURES MODERATE BACK
TOWARD NORMAL...THOUGH DEEP SNOW COVER FROM EARLY WEEK STORM WILL
TEMPER THINGS FOR SEVERAL DAYS. BLEND OF 925-950 TEMPS AND MOS USED
FOR TEMPS...THOUGH LEANED TOWARD COOLER ECMWF MINS WHERE SKIES
ACCOUNT SNOW COVER.
BEYOND FRIDAY...GUIDANCE IN GENERALLY GOOD AGREEMENT IN CONTINUING
TO SLOWLY MOVE UPPER RIDGE EAST ACROSS THE REGION INTO
SATURDAY...WHILE DEVELOPING UPPER LOW OVER THE SOUTHWESTERN CONUS
AND THEN SLOWLY LIFTING IT NORTHEAST ACROSS THE PLAINS. NEW 12Z
ECMWF REALLY SLOWS THINGS DOWN OVER PREVIOUS RUNS...AND ENDS UP
CUTTING OFF THE LOW OVER THE HIGH PLAINS INTO EARLY NEXT WEEK WHILE
ITS PREVIOUS RUN AND OTHER GLOBAL GUIDANCE LIFT IT NORTHEAST ACROSS
THE REGION MONDAY. WHILE SLOWER MAY VERY WELL END UP BETTER...HAVE
BASED EXTENDED PART OF FORECAST ON BETTER CONSENSUS AND AWAY FROM
12Z ECMWF. OVERALL THIS SUGGEST PRECIP THREAT EVENTUALLY INCREASES
SATURDAY NIGHT/SUNDAY AND MONDAY AS OCCLUDING LOW MOVES THROUGH THE
AREA. THICKNESS FIELDS/SOUNDINGS SUGGEST THIS SHOULD MAINLY BE A
RAIN EVENT FOR OUR AREA...WITH TEMPS INTO THE 40S/LOWER 50S BY
SUNDAY/MONDAY. WILL HAVE TO MONITOR HYDRO ISSUES AS THIS STORM
APPROACHES...AS WE WILL BE MELTING OFF THE DEEP EARLY WEEK SNOW PACK
AND THEN POTENTIALLY RAINING 0.5-1.00 INCHES OF RAIN BY THE
SUNDAY/MONDAY TIMEFRAME.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* HEAVY SNOW DURING THE AFTERNOON/EVENING HOURS.
* GUSTY NORTHEAST/NORTH WINDS CAUSING BLOWING SNOW.
BMD
//DISCUSSION...UPDATED 06Z...
OVERNIGHT...BROAD SCALE WEAK BUT PERSISTENT ASCENT WILL GRADUALLY
SATURATE THE ATMOSPHERE TOP DOWN WITH CIGS FALLING TO MVFR AND LIGHT
SNOW LIKELY STARTING AROUND THE SAME TIME. THIS DOWNWARD TREND HAS
BEEN OCCURRING SLOWER THAN ORIGINALLY THOUGHT...SO ADJUSTED TIMING
ACCORDINGLY...WITH THE EXPECTATION FOR MVFR CIGS/LIGHT SNOW TO BEGIN
AROUND OR SHORTLY BEFORE DAYBREAK TUESDAY.
MODELS CONTINUE TO BE IN GOOD AGREEMENT REGARDING THE POTENTIAL FOR
HEAVY SNOW...POINTING AT THE AFTERNOON TO EARLY EVENING HOURS HAVING
THE WORST CONDITIONS. DONT HAVE THE BEST CONFIDENCE REGARDING 1/4SM
PREVAILING FOR SUCH A LONG PERIOD...ESPECIALLY SINCE ITS BELOW
MET/MAV LOWEST GUIDANCE...BUT THINK THAT KEEPING TEMPO 1/4SM IS
STILL A GOOD CALL AS PERIODS OF HEAVY SNOW ARE LIKELY. STRONG
FORCING EARLY IN THE AFTERNOON IS CENTERED WELL WITHIN THE DENDRITIC
GROWTH ZONE LEADING TO EFFICIENT SNOW PRODUCTION AND SNOWFALL RATES
IN EXCESS OF AN INCH PER HOUR AT TIMES. LATER IN THE EVENING...THE
DGZ DEEPENS...AND DESPITE THE FORCING BECOMING SOMEWHAT
OFFSET...FEEL THE POTENTIAL FOR LESS THAN 1SM VSBY HEAVY SNOW
CONTINUES. IN ADDITION...VERY SHALLOW INSTABILITY DEVELOPS OVER LAKE
MICHIGAN LATE IN THE AFTERNOON AND EARLY EVENING WHICH MAY HELP TO
ENHANCE SNOWFALL IN THE CHICAGO AREA. NORTHEAST WINDS WILL BEGIN TO
INCREASE EVENING AS THE GRADIENT TIGHTENS AS STRONG PRESSURE RISES
TRANSLATE EAST ACROSS THE AREA. THIS WILL LEAD TO BLOWING SNOW AND
MAY FURTHER COMPLICATE VSBY FCST. CURRENT FORECAST IS FOR 7 TO 10
INCHES OF SNOW.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM CONFIDENCE IN CIG TRENDS THIS MORNING.
* HIGH CONFIDENCE IN HEAVY SNOW WITH PERIODS OF LESS THAN 1SM
VSBY...MEDIUM CONFIDENCE IN 1/4SM AT TIMES DURING THE
AFTERNOON...THOUGH LOW CONFIDENCE ON SPECIFIC TIMING/DURATION.
* MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...
WEDNESDAY...MVFR.
THURSDAY AND FRIDAY...VFR.
SATURDAY...SLIGHT CHANCE RAIN.
SUNDAY...SLIGHT CHANCE RAIN WITH HIGHER CHANCE SUNDAY NIGHT. MVFR
POSSIBLE SUNDAY NIGHT.
MDB
&&
.MARINE...
302 AM CST
MAIN CONCERN FOR LAKE MICHIGAN WILL BE WINDS PICKING UP TO AROUND 30
KT TODAY AS LOW PRESSURE DEVELOPS ACROSS THE MIDWEST. WINDS ARE
EXPECTED TO PEAK THIS EVENING AS THE GRADIENT BECOMES TIGHTEST BEHIND
THE DEPARTING AREA OF LOW PRESSURE OVER THE UPPER OHIO VALLEY AND
MODEST PRESSURE RISES MOVE ACROSS SOUTHERN LAKE MICHIGAN. THE
THREAT FOR LOW END GALES SEEMS INCREASINGLY UNLIKELY FROM THIS
EVENT. SNOW IS LIKELY OVER SOUTHERN PORTIONS OF LAKE MICHIGAN
TODAY...WITH SOME LAKE ENHANCEMENT/LAKE EFFECT SHOWERS THIS
EVENING AND TONIGHT. HIGH PRESSURE WILL MOVE ACROSS THE LAKE
THURSDAY INTO FRIDAY ALLOWING CONDITIONS TO IMPROVE...BUT WINDS
FRESHEN UP AGAIN LATE IN THE WEEKEND AS ANOTHER AREA OF LOW
PRESSURE MOVES INTO THE MIDWEST. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032-ILZ033-ILZ039 UNTIL MIDNIGHT WEDNESDAY.
IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL
MIDNIGHT WEDNESDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 3 AM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1154 PM CST MON MAR 4 2013
.DISCUSSION...
753 PM CST
MADE A FEW MINOR ADJUSTMENTS TO THE FORECAST OVERNIGHT REGARDING
THE ONSET OF PRECIP. SCATTERED LIGHT SNOW SHOWERS ARE ACROSS
MINNESOTA...WISCONSIN...AND IOWA AHEAD OF THE LOW PRESSURE SYSTEM.
WITH SLIGHTLY DRIER AIR OVER NORTHERN IL...NOT EXPECTING MUCH
SNOWFALL FROM THESE SNOW SHOWERS AS THEY MOVE INTO OUR AREA. IN
FACT NUMEROUS AREAS UNDER THE REFLECTIVITIES TO OUR WEST ARE NOT
REPORTING ANY PRECIP AT THE SFC. REDUCED POPS TO SLIGHT CHANCE
THROUGH MIDNIGHT WITH LITTLE TO NO SNOW EXPECTED.
THE SYSTEM IS MOVING A LITTLE SLOWER THAN EARLIER THOUGHT SO ALSO
LOWERED POPS BTWN MIDNIGHT AND 3AM TO CHANCE OR LESS. HRRR AND OUR
IN HOUSE ARW BOTH INDICATE SNOW WILL NOT REACH CENTRAL IL UNTIL
LATE TONIGHT AFTER 3AM. DID NOT GO AS SLOW AS THEY INDICATED AS
THE ATMOSPHERE COULD BECOME MORE SATURATED BY LIGHT FLURRIES
OVERNIGHT.
OTHERWISE THE GOING FORECAST LOOKS ON TRACK WITH THE HEAVIEST
SNOWFALL STILL EXPECTED FROM TOMORROW MORNING THROUGH THE EVENING
HOURS. NO CHANGES WERE MADE TO THE WINTER STORM WARNING. TRAVEL
WILL BE SEVERELY IMPACTED BY SNOWFALL RATES OF 1-2 INCHES PER HOUR
AND LOW VISIBILITIES. WINDS INCREASE TOMORROW EVENING AND BLOWING
SNOW TUESDAY EVENING AND OVERNIGHT WILL LIKELY REDUCE VISIBILITIES
TO A QUARTER MILE OR LESS AT TIMES.
JEE
//PREV DISCUSSION...
315 PM CST
SHORT RANGE...TONIGHT THROUGH TUESDAY NIGHT...
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE REST OF MY
COUNTIES FOR LATE TONIGHT THROUGH TUESDAY EVENING.
NOT MUCH HAS CHANGED FROM THE PREVIOUS THINKING. THE LATEST WATER
VAPOR IMAGERY PLACES THE CENTER OF THIS SYSTEM ACROSS THE DAKOTAS
THIS AFTERNOON. WARM AIR ADVECTION/ISENTROPIC ASCENT AHEAD OF THIS
FEATURE HAS LEAD TO A WEAK BAND OF MAINLY LIGHT SNOW AND FLURRIES
ACROSS THE AREA THIS AFTERNOON. THIS HAS NOT AMOUNTED TO MUCH AND
LIKELY WILL NOT THROUGH THIS EVENING. THE MAIN SHOW WILL GET GOING
LATE TONIGHT AND ON TUESDAY. THE GUIDANCE HAS DISAGREEMENTS ON THE
EXACT TIMING OF THE ONSET OF PRECIP...WITH THE ECMWF AND NAM
SUGGESTING THAT THE SNOW MAY HOLD OFF UNTIL DAYBREAK. I DID BACK
OFF ON POPS A BIT TONIGHT TO ACCOUNT FOR A LATER ONSET...BUT STILL
MENTION LIKELY POPS TOWARDS DAYBREAK.
ONCE THINGS GET GOING TUESDAY MORNING...IT APPEARS THE SNOW INCREASE
IN INTENSITY THROUGH THE LATE MORNING AND DURING THE AFTERNOON.
IMPRESSIVE FORCING FOR ASCENT IS PROGGED TO SET UP IN THE DENDRITIC
GROWTH ZONE DURING THE AFTERNOON AS ISENTROPIC ASCENT INCREASES
AHEAD THE APPROACHING MID LEVEL SYSTEM. IT ALSO APPEARS THAT A TROWAL
LIKE STRUCTURE WILL DEVELOP ACROSS THE REGION DURING THE AFTERNOON
AS THE 700 MB LOW TRACKS SOUTHEASTWARD FROM EASTERN IOWA AND ACROSS
CENTRAL ILLINOIS. THIS WILL LIKELY LEAD TO A DECENT BAND OF MID
LEVEL FRONTOGENESIS FROM NORTH-NORTHWEST TO SOUTH-SOUTHEAST RIGHT
ACROSS THE CWA. AS IT TYPICAL WITH THIS TYPE OF SETUP...LOW STATIC
STABILITY SETS UP IN THE MID LEVELS DUE TO STEEP LAPSE RATES. LOOKS
TO SET UP THE INGREDIENTS FOR PERIODS OF HEAVY SNOW ACROSS THE AREA
DURING THE AFTERNOON WITH SNOW RATES OF 1 TO 1.5 INCHES AT TIMES.
I STILL DO HAVE SOME CONCERNS FOR PRECIPITATION TYPES ACROSS MY
SOUTHERN COUNTIES INITIALLY TUESDAY MORNING. GUIDANCE CONTINUES TO
SUGGEST THAT ENOUGH WARM AIR MAY BE SQUEEZED NORTHWARD ACROSS
CENTRAL ILLINOIS TO RESULT IN SOME RAIN OR SLEET AND SNOW MIX
THROUGH MID TO LATE MORNING. THEREAFTER...STRONG DYNAMIC COOLING
ASSOCIATED WITH MID LEVEL HEIGHT FALLS AND STRONG ASCENT...SHOULD
LEAD TO ALL SNOW DURING THE AFTERNOON. ALTHOUGH SNOW TO LIQUID
RATIOS MAY ONLY BE 10:1 FOR A PERIOD FAR SOUTH...IT APPEARS THAT
HEAVY SNOW COULD STILL RESULT IN 6 OR MORE INCHES ACROSS THESE
AREAS...AND THEREFORE HAVE INCLUDED THEM IN THE WARNING.
SOME OF THE GUIDANCE HAS SHIFTED THE HEAVIEST PRECIP AXIS JUST A TAD
SOUTH. HOWEVER...WITH LAKE ENHANCEMENT LIKELY TUESDAY AFTERNOON AND
EVENING...PERIODS OF HEAVY SNOW STILL APPEARS TO BE A GOOD BET
ACROSS FAR NORTHEAST ILLINOIS.
WINDS WILL INCREASE OUT OF THE NORTH-NORTHEAST LATE TUESDAY AFTERNOON
AND NIGHT AS THE LOW DEEPENS ACROSS THE OHIO VALLEY. THESE WINDS
COULD GUST UP TO 30-35 MPH...RESULTING IN SOME BLOWING AND DRIFTING
SNOW. I ADDED BLOWING SNOW AREA-WIDE BY TUESDAY EVENING TO ACCOUNT
FOR THIS.
SNOW SHOULD BEGIN TO TAPPER OFF FROM WEST TO EAST ACROSS THE AREA
DURING THE EVENING ON TUESDAY. HOWEVER...SOME MODERATE TO HEAVY SNOW
MAY CONTINUE INTO THE LATER EVENING HOURS...ESPECIALLY ACROSS
EASTERN ILLINOIS AND INTO INDIANA. HOWEVER...SNOWFALL RATES SHOULD
DROP OFF SIGNIFICANTLY AFTER 06 UTC ON WEDNESDAY...WITH ONLY SOME
LAKE EFFECT SNOW SHOWERS CONTINUING INTO WEDNESDAY.
KJB
LONGER RANGE...WEDNESDAY THROUGH NEXT MONDAY...
THE MAIN CONCERNS BEYOND THE EARLY WEEK WINTER STORM INCLUDE THE
POTENTIAL FOR SOME LINGERING LAKE EFFECT SNOW WEDNESDAY INTO EARLY
THURSDAY...THEN AFTER A COUPLE OF QUIET DAYS A WARM-UP WITH THE
POTENTIAL FOR RAIN ARRIVES LATER IN THE WEEKEND AND EARLY NEXT WEEK.
STRONG UPPER/SURFACE LOWS ASSOCIATED WITH THE DEPARTING WINTER STORM
SYSTEM SHOULD BE DIGGING WELL OFF TO OUR SOUTHEAST ACROSS THE
CENTRAL/SOUTHERN APPALACHIANS AND OFF THE MID-ATLANTIC COAST
WEDNESDAY. GUIDANCE DOES DEPICT A RAPIDLY SHEARING/WEAKENING
MID-LEVEL VORT MOVING ACROSS THE AREA DURING THE MORNING HOURS...
THOUGH OVERALL RISING HEIGHTS/DEVELOPING UPPER RIDGING IS INDICATED
WITH LOW LEVEL COLD ADVECTION AND DECREASING CYCLONIC CURVATURE.
THIS PRODUCES SUBSIDENCE AND DRYING ABOVE THE BOUNDARY LAYER... WITH
LITTLE/NO SYNOPTIC SCALE FORCING FOR LINGERING PRECIP. WITHIN THE
BOUNDARY LAYER HOWEVER...NORTH-NORTHEAST FLOW DOWN LAKE MICHIGAN
PRODUCES LONG FETCH AND FAIRLY STRONG MOISTURE-CONVERGENCE ALONG THE
WEST/SOUTHWEST SHORE. THERMODYNAMIC PROFILES BASED ON 12Z WRF-NAM
AND GFS SHOW RELATIVELY MARGINAL SETUP FOR ORGANIZED SNOW SHOWERS
HOWEVER...WITH 850 MB TEMPS ONLY AROUND -8/9C WEDNESDAY AND
WEDNESDAY NIGHT. THIS YIELDS WATER SFC TO 850 MB DELTA T VALUES
AROUND 12/13...WITH COMPUTED EQUILIBRIUM LEVELS LESS THAN 5000 FT
AGL. WHILE SUFFICIENT TO PRODUCE LAKE EFFECT CLOUDS AND LIGHT SNOW
SHOWERS...THESE PARAMETERS SUGGEST IT WOULD BE DIFFICULT TO GET ANY
SIGNIFICANT ACCUMULATION UNLESS SNOW BAND WERE STATIONARY FOR A LONG
PERIOD OF TIME. LOW LEVEL WIND PROFILES INDICATE THAT CONVERGENCE
WILL FAVOR THE ILLINOIS SHORE INTO LAKE COUNTY INDIANA THROUGH
WEDNESDAY EVENING...THUS HAVE INDICATED SOME MINOR ACCUMULATION OF A
FEW TENTHS OF AN INCH THERE. IF STRONGER THERMODYNAMICS WERE TO
OCCUR OR THE BAND WERE TO EXPERIENCE A HIGHER RESIDENCE TIME IN ANY
ONE LOCATION PERHAPS AN INCH OR TWO COULD ACCUMULATE...THOUGH
CONFIDENCE IN THAT OCCURRING IS VERY LOW. HIGH PRESSURE RIDGE
SPREADS EAST ACROSS THE MISSISSIPPI VALLEY LATER WEDNESDAY NIGHT AND
THURSDAY...WHICH LEADS TO WINDS WEAKENING AND VEERING NORTHEAST
THURSDAY MORNING AND THEN EAST LATER IN THE DAY WITH THERMODYNAMIC
SETUP ALSO WEAKENING RAPIDLY BEYOND THURSDAY MORNING.
PERIOD OF QUIET WEATHER IS THEN ANTICIPATED AS UPPER RIDGE BUILDS
ACROSS THE CENTRAL CONUS...AND SURFACE HIGH PRESSURE RIDGE MOVES
SLOWLY ACROSS THE AREA INTO FRIDAY. TEMPERATURES MODERATE BACK
TOWARD NORMAL...THOUGH DEEP SNOW COVER FROM EARLY WEEK STORM WILL
TEMPER THINGS FOR SEVERAL DAYS. BLEND OF 925-950 TEMPS AND MOS USED
FOR TEMPS...THOUGH LEANED TOWARD COOLER ECMWF MINS WHERE SKIES
ACCOUNT SNOW COVER.
BEYOND FRIDAY...GUIDANCE IN GENERALLY GOOD AGREEMENT IN CONTINUING
TO SLOWLY MOVE UPPER RIDGE EAST ACROSS THE REGION INTO
SATURDAY...WHILE DEVELOPING UPPER LOW OVER THE SOUTHWESTERN CONUS
AND THEN SLOWLY LIFTING IT NORTHEAST ACROSS THE PLAINS. NEW 12Z
ECMWF REALLY SLOWS THINGS DOWN OVER PREVIOUS RUNS...AND ENDS UP
CUTTING OFF THE LOW OVER THE HIGH PLAINS INTO EARLY NEXT WEEK WHILE
ITS PREVIOUS RUN AND OTHER GLOBAL GUIDANCE LIFT IT NORTHEAST ACROSS
THE REGION MONDAY. WHILE SLOWER MAY VERY WELL END UP BETTER...HAVE
BASED EXTENDED PART OF FORECAST ON BETTER CONSENSUS AND AWAY FROM
12Z ECMWF. OVERALL THIS SUGGEST PRECIP THREAT EVENTUALLY INCREASES
SATURDAY NIGHT/SUNDAY AND MONDAY AS OCCLUDING LOW MOVES THROUGH THE
AREA. THICKNESS FIELDS/SOUNDINGS SUGGEST THIS SHOULD MAINLY BE A
RAIN EVENT FOR OUR AREA...WITH TEMPS INTO THE 40S/LOWER 50S BY
SUNDAY/MONDAY. WILL HAVE TO MONITOR HYDRO ISSUES AS THIS STORM
APPROACHES...AS WE WILL BE MELTING OFF THE DEEP EARLY WEEK SNOW PACK
AND THEN POTENTIALLY RAINING 0.5-1.00 INCHES OF RAIN BY THE
SUNDAY/MONDAY TIMEFRAME.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* TIMING CIGS DROPPING TO MVFR OVERNIGHT/EARLY TUESDAY MORNING.
* TIMING LIGHT SNOW STARTING OVERNIGHT.
* HEAVY SNOW DURING THE AFTERNOON/EVENING HOURS.
* GUSTY NORTHEAST/NORTH WINDS CAUSING BLOWING SNOW.
BMD
//DISCUSSION...UPDATED 06Z...
OVERNIGHT...BROAD SCALE WEAK BUT PERSISTENT ASCENT WILL GRADUALLY
SATURATE THE ATMOSPHERE TOP DOWN WITH CIGS FALLING TO MVFR AND LIGHT
SNOW LIKELY STARTING AROUND THE SAME TIME. THIS DOWNWARD TREND HAS
BEEN OCCURRING SLOWER THAN ORIGINALLY THOUGHT...SO ADJUSTED TIMING
ACCORDINGLY...WITH THE EXPECTATION FOR MVFR CIGS/LIGHT SNOW TO BEGIN
AROUND OR SHORTLY BEFORE DAYBREAK TUESDAY.
MODELS CONTINUE TO BE IN GOOD AGREEMENT REGARDING THE POTENTIAL FOR
HEAVY SNOW...POINTING AT THE AFTERNOON TO EARLY EVENING HOURS HAVING
THE WORST CONDITIONS. DONT HAVE THE BEST CONFIDENCE REGARDING 1/4SM
PREVAILING FOR SUCH A LONG PERIOD...ESPECIALLY SINCE ITS BELOW
MET/MAV LOWEST GUIDANCE...BUT THINK THAT KEEPING TEMPO 1/4SM IS
STILL A GOOD CALL AS PERIODS OF HEAVY SNOW ARE LIKELY. STRONG
FORCING EARLY IN THE AFTERNOON IS CENTERED WELL WITHIN THE DENDRITIC
GROWTH ZONE LEADING TO EFFICIENT SNOW PRODUCTION AND SNOWFALL RATES
IN EXCESS OF AN INCH PER HOUR AT TIMES. LATER IN THE EVENING...THE
DGZ DEEPENS...AND DESPITE THE FORCING BECOMING SOMEWHAT
OFFSET...FEEL THE POTENTIAL FOR LESS THAN 1SM VSBY HEAVY SNOW
CONTINUES. IN ADDITION...VERY SHALLOW INSTABILITY DEVELOPS OVER LAKE
MICHIGAN LATE IN THE AFTERNOON AND EARLY EVENING WHICH MAY HELP TO
ENHANCE SNOWFALL IN THE CHICAGO AREA. NORTHEAST WINDS WILL BEGIN TO
INCREASE EVENING AS THE GRADIENT TIGHTENS AS STRONG PRESSURE RISES
TRANSLATE EAST ACROSS THE AREA. THIS WILL LEAD TO BLOWING SNOW AND
MAY FURTHER COMPLICATE VSBY FCST. CURRENT FORECAST IS FOR 7 TO 10
INCHES OF SNOW.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN CIG TRENDS OVERNIGHT INTO EARLY TUESDAY.
* LOW TO MEDIUM CONFIDENCE LIGHT SNOW START TIME EARLY TUESDAY.
* HIGH CONFIDENCE IN HEAVY SNOW WITH PERIODS OF LESS THAN 1SM
VSBY...MEDIUM CONFIDENCE IN 1/4SM AT TIMES DURING THE
AFTERNOON...THOUGH LOW CONFIDENCE ON SPECIFIC TIMING/DURATION.
* MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...
WEDNESDAY...MVFR.
THURSDAY AND FRIDAY...VFR.
SATURDAY...SLIGHT CHANCE RAIN.
SUNDAY...SLIGHT CHANCE RAIN WITH HIGHER CHANCE SUNDAY NIGHT. MVFR
POSSIBLE SUNDAY NIGHT.
MDB
&&
.MARINE...
232 PM...LOW PRESSURE OVER THE SOUTHERN PLAINS WILL MOVE NORTHEAST
TO THE OHIO VALLEY TUESDAY MORNING AS IT ABSORBS A WEAKER AREA OF
LOW PRESSURE MOVING SOUTHEAST FROM THE DAKOTAS. THIS LOW WILL THEN
QUICKLY DEEPEN JUST OFF THE MID ATLANTIC COAST WEDNESDAY. AS THE
LOW APPROACHES...THE GRADIENT WILL TIGHTEN BETWEEN A LARGE RIDGE
OF HIGH PRESSURE OVER THE PLAINS AND SOUTHERN CANADA. NORTHERLY
WINDS WILL INCREASE TO 30 KTS BY TUESDAY AFTERNOON AND CONTINUE
INTO TUESDAY NIGHT. WINDS WILL SLOWLY DIMINISH WEDNESDAY NIGHT AS
THE RIDGE SPREADS ACROSS THE REGION THURSDAY. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-
ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO
MIDNIGHT WEDNESDAY.
WINTER STORM WARNING...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019
UNTIL MIDNIGHT WEDNESDAY.
IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019...3 AM
TUESDAY TO MIDNIGHT WEDNESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...3 AM TUESDAY TO 3 AM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1138 PM CST MON MAR 4 2013
.AVIATION...
A SURFACE TROF DEVELOPING FROM SOUTHEAST IOWA THROUGH NORTHWEST
IOWA OVERNIGHT WILL MOVE SOUTH INTO MISSOURI BY LATE TUESDAY
AFTERNOON. SNOW WILL CONTINUE TO SPREAD OVER THE AREA LATE TONIGHT
AND TAPER OFF TUESDAY AFTERNOON AS THE TROF MOVES SOUTH. NORTH
TO NORTHWEST WINDS WILL INCREASE LATE TUESDAY MORNING AND INTO THE
AFTERNOON WITH GUSTS AROUND 25KTS ESPECIALLY WEST OF THE
MISSISSIPPI RIVER.
CONDITIONS WILL DETERIORATE EARLY THIS MORNING WITH WIDESPREAD
MVFR CIGS IN THE 1KFT TO 2KFT DEVELOPING BY 3 AM THEN LOWERING
BELOW 1KFT BY 6 AM. THE DEVELOPING SNOW WILL DROP VSBYS DOWN TO
AROUND A MILE BETWEEN 3 AM AND 6 AM WITH VISIBILITIES FREQUENTLY
DOWN TO A HALF MILE OR LESS FROM 6AM THROUGH NOON. THE SNOW SHOULD
TAPER OFF DURING THE AFTERNOON BUT INCREASING NORTH AND NORTHWEST
WINDS WILL CAUSE BLOWING SNOW WHICH COULD AID IN KEEPING
VISIBILITIES UNDER 3 MILES THROUGH THE AFTERNOON. BY LATE
AFTERNOON OR EARLY EVENING THE BLOWING SNOW WILL END AS THE WINDS
DIMINISH. CIGS SHOULD REMAIN AROUND 1KFT THROUGH MIDNIGHT.
DLF
&&
.PREV DISCUSSION... /ISSUED 922 PM CST MON MAR 4 2013/
UPDATE...
JUST SENT AN UPDATE TO LOWER POPS WEST BY A CATEGORY FOR THE REST
OF THE THIS EVENING. THE PRECIP HAS BEEN SLOWER TO EVOLVE THAN
PREVIOUSLY EXPECTED AND IT NOW LOOKS LIKE ANY SIGNIFICANT
PRECIP/SNOW SHOULD NOT BEGIN UNTIL AFTER MIDNIGHT. REGIONAL RADAR
COMPOSITES WERE SHOWING AN EXPANSION OF LIGHT RETURNS OVER WESTERN
IOWA THE PAST HOUR BETWEEN SOME HIGHER REFLECTIVITY/S MOVING
NORTHEAST OUT OF NORTH CENTRAL MO MORE SHOWERY LOOKING PRECIP FROM
NORTHERN IA INTO MN. THE CURRENT THINKING IS THE NORTHERN MO/IA
AREAS WILL MERGE THE NEXT FEW HOURS WITH THE BETTER FORCING AHEAD
OF THE NORTHERN PLAINS UPPER LOW MOVING IN.
NO OTHER CHANGES WERE MADE TO THE FORECAST CONCERNING SNOW FALL
AMOUNTS OR HEADLINES. THE 00Z NAM CAME IN WITH AN UPPER LOW TRACK
NORTHEAST OF THE MONDAYS RUNS SUGGESTING LOWER SNOW AMOUNTS...BUT
THE NAM HAS BEEN A NORTHEASTERN OUTLIER WITH THIS SYSTEM ON SEVERAL
RUNS. THE LATEST RAP RUNS CONTINUE TO MOVE THE UPPER LOW ALONG A
SIMILAR TRACK AS MONDAY/S MODEL RUNS SUGGESTED.
DLF
PREV DISCUSSION... /ISSUED 625 PM CST MON MAR 4 2013/
AVIATION...
A SURFACE TROF WILL DEVELOP OVER THE AREA OVERNIGHT AND THEN MOVE
SOUTH INTO MISSOURI BY LATE TUESDAY AFTERNOON. WIDESPSREAD SNOWS
ARE EXPECTED TO SPREAD OVER THE AREA TONIGHT WITH THE DEVELOPING
TROF THEN TAPER OFF TUESDAY AFTERNOON. NORTH TO NORTHWEST WINDS
WILL INCREASE LATE TUESDAY MORNING AND INTO THE AFTERNOON WITH
GUSTS AROUND 25KTS ESPECIALLY WEST OF THE MISSISSIPPI RIVER.
GENERALLY VFR WITH SOME PATCHY MVFR CIGS NORTH THIS EVENING WILL
GRADUALLY DETERIORATE BY LATE EVENING WITH WIDESPREAD MVFR CIGS IN
THE 1KFT TO 2KFT RANGE BY MIDNIGHT. SOME SCATTERED SNOW SHOWERS
NORTH OR RAIN/SNOW SHOWERS SOUTH ARE POSSIBLE DURING THE EVENING.
BY LATE EVENING IFR CIGS WILL BE POSSIBLE IN EAST CENTRAL IA.
AFTER MIDNIGHT COUNTDOWNS WILL RAPIDLY DETERIORATE TO IFR AND
LIFR AS THE SNOW SPREADS OVER THE AREA. THE LOWEST CONDITIONS WILL
LIKELY OCCUR BETWEEN 09Z AND 18Z DUE OBSCURED CEILINGS AND
MODERATE TO HEAVY SNOW REDUCING VISIBILITIES TO A HALF MILE OR
LESS AT TIMES. WINDS DURING THIS TIME WILL BE LIGHT.
THE SNOW SHOULD BE TAPERING OFF SOME DURING THE AFTERNOON BUT
NORTH TO NORTHWEST WINDS WILL BE INCREASING CAUSING CONSIDERABLE
BLOWING SNOW WHICH WILL CONTRIBUTE TO VISIBILITIES STAYING AROUND
A MILE THROUGH THE AFTERNOON.
DLF
PREV DISCUSSION... /ISSUED 352 PM CST MON MAR 4 2013/
DISCUSSION...
SHORT TERM...ASSESSING A PLETHORA OF PARAMETERS ON MANY OF THE
VARIOUS 12Z RUN MODELS...IT IS APPARENT THAT THERE IS SOMEWHAT
SOUTHWESTWARD ADJUSTMENT OF THE MID LEVEL LOW AS WELL AS LOW TO
MID LEVEL FORCING ALONG THE INCOMING VORT GRADIENT FLANK TARGETING
AREAS FROM NEAR VINTON IOWA...SOUTHEASTWARD TO THE NORTHERN QUAD
CITIES...AND THEN PUSHING EASTWARD ALONG THE I-80 CORRIDOR EAST OF
THE QUAD CITIES LATE TONIGHT AND TUESDAY. WITH SIGNALS OF A LOW TO MID
LEVEL TROWAL SIGNATURE WRAPPING BACK AROUND THE LOW-MID LEVEL
LOW/S AND LLVL INVERTED SFC TROF WITH PLENTY OF LLVL CONVERGENT
STAYING POWER LATE TONIGHT AND ESPECIALLY ON TUE...HAVE ADJUSTED
HIGHER SNOWFALL AMOUNTS MORE FROM NORTHWEST TO SOUTHEAST ACRS THE
NORTHEASTERN HALF OF THE DVN CWA. 7.5 TO 9.5 INCHES AND ISOLATED
10+ INCH AMOUNTS NOW LOOK POSSIBLE BY 00Z WED GENERALLY ALONG AND
EAST OF A LINE FROM INDEPENDENCE IA...TO THE QUAD CITIES...AND
CAMBRIDGE/HENRY CO IL. WIDESPREAD 5.5 UP TO 8 INCHES ALONG AND
NORTH OF I80 WEST OF THE QUAD CITIES TO THIS LINE. PIVOTING DEF
ZONE MAY FOCUS EVEN HIGHER AMOUNTS FROM EAST OF CEDAR
RAPIDS...THOUGH STERLING IL AND PRINCETON IL TUE AFTERNOON. 3 TO
6 INCH AMOUNTS SOUTH OF I80 TO THE HWY 34 CORRIDOR....AND 3-4
INCHES SOUTH OF HWY 34 ACRS THE REST OF THE SOUTHERN CWA. THESE
AMOUNTS DERIVED USING THE EXTENT OF MOISTURE INFLUX...LSR/S OF
13:1 TO 15:1 AND ACCEPTED FORCING AND LONG DURATION. THESE AMOUNTS
ARE JUST THOUGH 00Z. SOME ADDITIONAL ACCUMS PAST 00Z WED IN THE
EAST...SEE DISCUSSION BELOW.
SO ALL IN ALL...HAVE EXPANDED THE WARNING TO THE CENTRAL I80
CORRIDOR AND THEN EAST OF THE QUAD CITIES THROUGH PUTNAM CO IL.
HAVE SPLIT UP START TIMES WITH THE EAST HALF NOT UNTIL AFTER 06Z
TONIGHT THROUGH 06Z WED. ADVISORIES EXPANDED SOUTHWARD TO INCLUDE
THE ENTIRE CWA AS WELL. SPLIT THE ADVISORY FROM WEST TO EAST WITH
START TIMES OF 00Z WEST OF THE MS RVR...AND 06Z TO THE EAST. BUT
EVEN IN THE WESTERN ADVISORY AREA ACCUMULATING SNOW NOT LIKELY TO START
TIL AFTER 03Z-04Z TUE OR SO. SFC WINDS INCREASING TO 15 TO 25 MPH WITH
GUSTS UP T0 35 MPH WRAPPING AROUND DEPARTING SFC TROF AS TUE
PROGRESSES. THUS THE AFTERNOON AND EVENING THE PRIME TIME FOR
DRIFTING AND SOME BLOWING SNOW TO COMPOUND TRAVEL CONDITIONS.
ANOTHER REASON OF EXPANDING THE ADVISORIES SOUTHWARD ALONG WITH
SOME SNOWFALL ADJUSTMENT UPWARD IN THOSE SOUTHERN AREAS. ..12..
LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
HEADLINES...HAVE EXTENDED THE WARNINGS/ADVISORIES IN OUR EASTERN CWA
TO MIDNIGHT TUESDAY NIGHT TO COVER THE TAIL END OF THE WINTER STORM.
TUESDAY NIGHT...HIGH CONFIDENCE. ADDITIONAL ACCUMULATIONS IN OUR
EASTERN HALF CWA IN THE EVENING WILL BE AROUND AN INCH OR LESS.
HOWEVER...NORTH WINDS WILL BE GUSTING TO 25 TO 30 MPH. TEMPERATURES
DURING THE EVENING WILL BE IN THE 20S SO BLOWING AND DRIFTING WILL
ADD TO TRAVEL DIFFICULTIES. THIS IS THE REASON FOR EXTENDING THE
WARNING TO MIDNIGHT. AFTER MIDNIGHT THE SNOW SHOULD HAVE ENDED IN
OUR FAR EAST AND WINDS AND CLOUDS DECREASE OVERNIGHT AS THE SYSTEM
PUSHES WELL OFF TO OUR EAST. MINIMUM TEMPERATURES WILL BE IN THE
TEENS NORTH TO AROUND 20 SOUTH.
WEDNESDAY THROUGH FRIDAY...MEDIUM TO HIGH CONFIDENCE. THIS IS A DRY
PERIOD. WE START OUT COLD WEDNESDAY AND WEDNESDAY NIGHT WITH HIGH
PRESSURE OVER THE CWA. BUT THEN ZONAL FLOW AND MILDER TEMPERATURES
RETURN LATE IN THE WEEK. WITH HIGH PRESSURE PROVIDING MOSTLY CLEAR
SKIES AND LIGHT WINDS ON WEDNESDAY NIGHT I HAVE LOWERED TEMPERATURES
FROM PREVIOUS SHIFT. THIS IS ESPECIALLY TRUE WITH A FRESH SNOW PACK.
WILL FORECAST SINGLE DIGITS NORTH AND TEENS SOUTH BUT THIS MAY STILL
NOT BE COLD ENOUGH. IF WE ARE TOTALLY CLEAR AND WINDS ARE CALM SOME
LOCATIONS MAY DIP BELOW ZERO IN OUR FAR NORTH.
FRIDAY NIGHT THROUGH MONDAY...LOW CONFIDENCE. STRONG STORM SYSTEM
WILL BE TRACKING OUT OF THE SOUTHERN ROCKIES/SOUTHERN PLAINS AND
THEN INTO THE MIDWEST. HOWEVER...AS USUAL A WEEK AWAY THE MODELS ARE
HAVING DIFFICULTY WITH STRENGTH AND TIMING OF THE SYSTEM. THE GFS
SUGGESTS A WET WEEKEND BUT THE ECMWF HAS SLOWED THE SYSTEM FROM
PREVIOUS RUNS AND KEEP THINGS DRY UNTIL MONDAY. BASED ON CONSENSUS
MODEL DATA THE GRIDS WILL HAVE CHANCE POPS FOR SATURDAY THROUGH
MONDAY. HOWEVER LATER SHIFTS MAY EITHER NEED TO ADJUST OR ELIMINATE
POPS ONCE CONFIDENCE IN THE MODEL DATA INCREASES.
HAASE
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WARNING UNTIL MIDNIGHT CST TUESDAY NIGHT FOR
CLINTON-DUBUQUE-JACKSON-MUSCATINE-SCOTT.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TUESDAY NIGHT FOR DES
MOINES-LOUISA.
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR BENTON-BUCHANAN-
CEDAR-DELAWARE-JOHNSON-JONES-LINN.
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR HENRY IA-IOWA-
JEFFERSON-KEOKUK-LEE-VAN BUREN-WASHINGTON.
IL...WINTER STORM WARNING UNTIL MIDNIGHT CST TUESDAY NIGHT FOR BUREAU-
CARROLL-HENRY IL-JO DAVIESS-PUTNAM-ROCK ISLAND-STEPHENSON-
WHITESIDE.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TUESDAY NIGHT FOR
HANCOCK-HENDERSON-MCDONOUGH-MERCER-WARREN.
MO...WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR CLARK-
SCOTLAND.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1146 PM CST MON MAR 4 2013
...UPDATED FOR THE 06Z TAF AND AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 254 PM CST MON MAR 4 2013
WATER VAPOR AND HOURLY RAP ANALYSES SHOW A FAIRLY COMPACT JET STREAK
MOVING SOUTHEAST FROM IDAHO INTO COLORADO. THIS JET STREAK WAS WELL
TO THE SOUTHWEST OF THE MAIN UPPER LOW CENTER WHICH WAS CENTERED
ALONG THE WESTERN SOUTH DAKOTA-NORTH DAKOTA BORDER. THE FIRST
FRONTAL PASSAGE OCCURRED EARLIER IN THE DAY, BUT THE AIRMASS BEHIND
THIS FRONT WAS MAINLY DOWNSLOPE MODIFIED CONTINENTAL POLAR AIR...AND
NOT ARCTIC IN NATURE AT ALL. BECAUSE OF THIS...INSOLATION AND
CONTINUED DOWNSLOPE MODIFICATION YIELDED AFTERNOON TEMPERATURES
QUITE MILD AND RIGHT AROUND THE SEASONAL AVERAGE FOR EARLY MARCH.
THE EXCEPTION OF THIS WAS ACROSS SOUTH CENTRAL KANSAS WHERE
LINGERING SNOWPACK CONTINUED GENERALLY FROM HAYS TO KINSLEY TO
COLDWATER AND POINTS EAST (ESPECIALLY PRATT AND BARBER COUNTIES).
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 254 PM CST MON MAR 4 2013
LOWER-MID LEVEL CLOUD WILL CONTINUE TO INCREASE LATE THIS AFTERNOON
AND EVENING AS UPWARD VERTICAL MOTION INCREASES AHEAD OF THE
APPROACHING JET STREAK. RADAR ECHOES CONTINUED TO INCREASE ACROSS
NORTHEASTERN COLORADO AND AS THE UPPER JET STREAK APPROACHES WESTERN
KANSAS...FRONTOGENESIS IN THE MID TROPOSPHERE WILL FURTHER
INCREASE...AND RAIN/SNOW SHOWERS WILL INCREASE IN COVERAGE. POPS
WERE INCREASED TO THE 30-40 PERCENT ACROSS FAR WEST CENTRAL
KANSAS...AND THE CHALLENGE OF PRECIPITATION TYPE IS PRETTY HIGH
GIVEN THE RAPID COOLING OF THE 900-800MB LAYER EARLY THIS EVENING AS
THE SECOND COLD FRONT MOVES THROUGH AND EVAPORATIVE COOLING ENSUES.
THE INCREASING RADAR TRENDS ACROSS NORTHWEST KANSAS WOULD SUGGEST AN
INCREASE IN POPS ACROSS THE BOARD...SO BY PRESS TIME BEFORE 21Z WILL
HAVE POPS INCREASED AND SLIGHTLY HIGHER QPF AMOUNTS. THE PERIOD FROM
ROUGHLY 00Z TO 06Z WILL BE THE BEST TIME FRAME FOR LIGHT
ACCUMULATING PRECIPITATION AS THE 700MB FRONTOGENETIC MOVES QUICKLY
SOUTHEAST ACROSS WESTERN KANSAS. WILL BEGIN A RAPID CLEARING TREND
IN THE GRIDS TOWARD DAYBREAK TUESDAY. WE WILL REMAIN IN A FAIRLY
STRONG 850-700MB GRADIENT THROUGH MOST OF THE DAY TUESDAY WHICH WILL
KEEP WINDS UP IN THE BREEZY TO WINDY CATEGORY...BUT REMAINING BELOW
WIND ADVISORY CRITERIA AS IT LOOKS RIGHT NOW. HIGH TEMPERATURE
FORECAST WILL NOT BE CHANGED FROM THE GOING FORECAST WITH WIDESPREAD
LOWER TO MID 40S EXPECTED.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 324 PM CST MON MAR 4 2013
GOOD POTENTIAL EXISTS FOR COLDER TEMPERATURES OVERNIGHT TUESDAY
INTO EARLY WEDNESDAY MORNING. THE CENTER OF THE HIGH PRESSURE
SURFACE RIDGE AXIS WILL LIKELY BE CENTERED ACROSS CENTRAL KANSAS FOR
SEVERAL HOURS TUESDAY NIGHT. THIS WILL ALSO BE UNDER A VERY DRY DEEP
ATMOSPHERIC COLUMN, PROMOTING LONGWAVE RADIATIONAL COOLING.
SURFACE WINDS WILL QUICKLY TURN SOUTHEASTERLY ON THE WEST SIDE OF
THE RIDGE EARLY WEDNESDAY MORNING, AND EVEN BEFORE THAT ACROSS FAR
WESTERN KANSAS. THE MESOSCALE NAM INDICATES A POCKET OF THE COLDEST
POSSIBLE TEMPERATURES OF ALL MODEL OUTPUT AND MOS GUIDANCE. HOWEVER
IT APPEARS TO BE HAVING PROBLEMS ACCOUNTING FOR LEFTOVER SURFACE
SNOWDEPTH. THE ECMWF MOS APPEARS A GENERALLY REASONABLE BETTER
COMPROMISE IN THIS INSTANCE, AND WAS CLOSELY FOLLOWED WEDNESDAY
MORNING.
WEDNESDAY AFTERNOON WILL BRING WARMER TEMPERATURES, ESPECIALLY ACROSS
WESTERN KANSAS. THE NAM MODEL INDICATES A SHARP 850 MB LEVEL
TEMPERATURE GRADIENT ACROSS FROM AROUND DODGE CITY TO THE COLORADO
LINE, WITH SOUTHERLY SURFACE WINDS AROUND A DEVELOPING LEE SURFACE
LOW. EVEN WARMER BOUNDARY LAYER AIR WILL BE PRESENT EARLY BY
THURSDAY AFTERNOON. BY THURSDAY THE AXIS OF THE MID LEVEL THERMAL
RIDGE BECOMES CENTERED OVER THE HIGH PLAINS, AND THE SURFACE TROUGH
PULLS SLIGHTLY FARTHER EASTWARD, DRAWING IN WARMER AIR FROM THE
HIGHER TERRAIN OF SE COLORADO AND NE NEW MEXICO. WARMER OVERNIGHT
LOWS WILL BE EXPERIENCED AS WELL AS PERSISTENT SOUTHERLY WINDS
DURING THE OVERNIGHTS IN SLIGHTLY HIGHER THETA-E AIR. MELTING SNOW
IS LIKELY TO RE-FREEZE IN MOST CASES, AND IT IS NOT OBVIOUS AT THIS
POINT OF ANY NIGHTS APPEARING OVERLY PRONE TO DENSE FOG DEVELOPMENT.
A BETTER CHANCE FOR DENSE FOG WILL COME CLOSER TO THE BEGINNING OF
THE DYNAMIC LOW EXPECTED THIS WEEKEND STARTING AROUND FRIDAY.
LARGE UNCERTAINTY EXISTS WITH RESPECT TO THE STORM SYSTEM EXPECTED TO
INTENSIFY ACROSS THE CENTRAL HIGH PLAINS REGION BETWEEN FRIDAY AND
SUNDAY. THE ECMWF AND CANADIAN (GEM) MODELS ARE IN GENERALLY CLOSER
AGREEMENT TO ONE ANOTHER WITH A MORE BAROCLINIC SYSTEM, AS WELL AS
CONSIDERABLY SLOWER THAN THE GFS MODEL (BY AROUND 12 HOURS). THE
RECENT MODEL CONSENSUS, BLENDED WITH THE LAST FORECAST DOES LOWER
PROBABILITIES ON FRIDAY AND FRIDAY NIGHT, AND FOCUSES THE HIGHER
(LIKELY) CHANCES SATURDAY INTO SUNDAY. TEMPERATURES WILL ALSO BE A
CHALLENGE DURING THIS PERIOD. THE TRACK AND NATURE OF THE DYNAMIC
LOW WILL MAKE A LARGE DIFFERENCE, WITH A HIGH TEMPERATURE ENSEMBLE
SPREAD SATURDAY FROM THE LOW 40S TO LOW 60S. BETTER MODEL AGREEMENT
WILL BE LOOKED FOR AS THE SYSTEM BECOMES BETTER SAMPLED LATER IN THE
WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1140 PM CST MON MAR 4 2013
THE REST OF TONIGHT WILL BE BREEZY WITH NORTH TO NORTHWEST WINDS
OF 15G25KT. VFR CONDITIONS WILL PREVAIL THROUGH THE 24 HOUR TAF
PERIOD. MID LEVEL CLOUDS IN THE BKN-OVC090-120 FOOT RANGE WILL
CONTINUE TO CLEAR TO THE EAST, LEAVING CLEAR SKIES BY 10Z. AS
HIGH PRESSURE BUILDS IN TUESDAY AFTERNOON, WINDS WILL DROP TO
LESS THAN 10 KNOTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 22 48 17 54 / 80 0 0 0
GCK 20 49 16 56 / 80 0 0 0
EHA 22 50 24 63 / 80 10 0 0
LBL 20 49 19 59 / 80 10 0 0
HYS 22 40 14 46 / 70 10 0 0
P28 25 42 16 49 / 30 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...RUSSELL
AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
337 AM EST TUE MAR 05 2013
.Short Term (Now - Wednesday)...
Issued at 335 AM EST Tue Mar 5 2013
...Accumulating Snow Likely Tonight through Wed Morning...
A weak sfc low over Arkansas this morning will combine with a potent
upper low diving southeast across the Plains/Midwest to result in a
potent low pressure system strengthening over the Ohio Valley and
becoming nearly vertically stacked as it reaches the
Virginias/Carolinas by Wed afternoon. This system will be our main
focus for the next 24-36 hrs bringing rains and a few rumbles of
thunder today and then accumulating snow tonight into Wed.
Early this morning, good isentropic lift ahead of the aforementioned
sfc low was causing good rains to travel along and south of a sfc
trough over central KY. Thus, will continue 70-90% POPs through the
pre-dawn hours. The latest RAP guidance indicates that as the sfc
low moves into western KY around sunrise, we will start to see
precip become more isld-sct in nature for the rest of the morning
before ramping up again by early afternoon as the sfc low deepens
and moves through central KY. Also by late morning through early to
mid afternoon, an axis of instability with pass through south
central KY possible causing isld-sct embedded t-storms. T-storms
should remain relatively weak/elevated however.
The biggest threat with this weather system will arrive tonight as
the sfc low rapidly deepens in response to the arrival of the strong
upper low diving south into the Ohio Valley. This will create a
strong surge of cold air at the sfc with a trowal/comma head like
structure developing aloft. This setup will be favorable for
accumulating snows over southern Indiana and much of central KY.
Looking at soundings, rains should change over to snow from NW to SE
tonight between about 7-11 pm. Soundings suggest a decent period
during the overnight hours for accumulating snows especially over
southern Indiana and central KY along and north of I-64. Deep
moisture and combined with good forcing throughout the column should
could result in some moderate to heavy bands of snow overnight.
Overall think that 2-4 inches could accumulate overnight tonight
through Wed morning over much of southern Indiana and north
central/east central KY including the Louisville/Lexington metro
areas. South and east of this area, lesser amounts (up to 2 inches
would be most likely based on the latest model guidance. With these
advisory level snow accums in mind and the fact that snow will
likely be ongoing still during the Wed morning rush, went ahead and
decided to issue a Winter Wx Advy for this package which will run
from 0Z-18Z Wed. Adjustments to this advisory may need to be made
based on coming model runs today. Portions of southeast Indiana
and extreme northern KY may even stand a chance at 4+ inches of snow
accums, but did not feel confident enough in issuing anything more
than an winter wx advy at this point due to a pretty decent model
spread in snow accums. Drivers should plan extra travel time for
the Wed morning commute and use caution while driving in snow.
In addition to the snow for tonight into Wed morning, westerly winds
will gust into the 30-35 mph range especially during the pre-dawn
hours possibly resulting in some blowing snow. Winds should subside
somewhat by the rush hour however.
Highs today should reach the lower 40s to mid 50s. Lows tonight
should reach the upper 20s to around 20 degrees.
By late Wed morning or early afternoon, moisture will begin to pull
out of our area leaving isld snow showers or even just some
rain/drizzle on the back side as we lose ice crystals aloft and sfc
temps warm into the mid 30s for highs on Wed.
.Long Term (Wednesday Night through Monday)...
Issued at 255 AM EST Tue Mar 5 2013
Wednesday Night through Friday Night...
Current suite of deterministic and ensemble guidance is in pretty
good agreement through this portion of the forecast period. The
guidance suggest that the closed upper low will be exiting off the
US Mid-Atlantic coast at the beginning of the forecast period.
Upstream ridging to our west will gradually build into the region on
Thursday and Friday resulting in dry conditions along with a
moderating trend in temperatures. Cloudiness will likely be a
little to clear out Wednesday night as model time-height cross
sections show low-level moisture hanging around. More sufficient
clearing will take place on Thursday with partly cloudy skies and we
should see mostly sunny skies across the region on Friday.
Temperatures are a bit of a concern depending on how much snowfall
occurs with the Tuesday night/Wednesday system. For now have
trended the forecast a little on the cooler side of the guidance
envelope with upper 20s for lows Thursday morning. There is a bit
of spread in the guidance for Thursday. Feel that sticking close to
a blend of the ensemble guidance and the AllBlend (all model
consensus) is probably a good start at this point. Highs will range
from the lower-mid 40s in the north/northeastern sections with
middle 40s in the central and southwest sections. Lows Thursday
night and Friday morning should cool into the mid-upper 20s once
again due to good radiational cooling effects. Milder conditions
look likely for Friday with highs generally in the 50-55 degree
range with lows Friday night cooling into the lower 30s.
Saturday through Monday...
As we enter into the weekend, mid-level ridge axis is forecast to be
nearly overhead across the Ohio Valley as two large cutoff lows will
be to our east and west. This ridge axis should hold into Sunday as
well providing the area with mostly dry conditions along with milder
temperatures. Highs on Saturday have trended a little cooler in
tonight`s datasets. Still thinking that we`ll see highs in the
55-60 degree range on Saturday with highs in the lower 60s on
Sunday. Next weather maker looks to push into the region around
Monday as a large cutoff low pressure system out to our west slowly
churns eastward. There is a bit of spread between the more
progressive GFS solution and the slower Euro runs, for now have gone
closer to the Euro solution as the general model consensus is
usually too progressive/fast in the long term. Nonetheless, a
period of unsettled weather looks likely early next week along with
a cooldown in temperatures. Highs on Monday are likely to top out
in the upper 50s to the lower 60s.
&&
.Aviation (06Z TAF Issuance)...
Issued at 1235 AM EST Tue Mar 5 2013
Isentropic lift ahead of an approaching sfc low will bring rain
showers and thickening low clouds to the area early this morning.
Expect rain showers to begin at the TAF sites within the next 1-3
hrs with MVFR cigs arriving just before sunrise according the 0Z NAM
soundings and gridded LAMP guidance. It`s not totally out of the
question that BWG could see a rumble of thunder as well, but not
confident enough to put in the TAF at this time as lightning obs
upstream remain very sparse.
The sfc low will move through central KY this afternoon. While we
may see a lull in or widely scattered rain shower activity during
the mid to late morning hours across the area, steady rains should
again pick up by early afternoon. Most models are picking up the
arrival of IFR cigs before the main push of rain. While this may be
possible, have generally delayed lower cigs in the first 6 hours of
the TAFs so IFR after sunrise may be delayed as well. Will need to
monitor this morning.
By late afternoon or early evening the sfc low will pass to our east
causing sfc winds to veer to the west and become gusty as colder air
rushes in. The latest models indicate a trowal/comma head like
structure on the back side of this weather system will bring
additional moisture in the from of -RASN then -SN tonight. Cigs
should improve to low MVFR levels by this evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......AMS
Long Term........MJ
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1217 AM EST TUE MAR 5 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM EST MON MAR 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER THE
WRN DAKOTAS AND A DOWNSTREAM RIDGE OVER THE WRN GREAT LAKES. AT THE
SFC...A RIDGE EXTENDED FROM NRN MANITOBA AND NW ONTARIO INTO UPPER
MI BRINGING EASTERLY WINDS AND MAINLY CLEAR SKIES. CLOUDS ASSOCIATED
WITH THE BROAD AREA OF ISENTROPIC LIFT AHEAD OF THE SFC LOW VOER S
CNTRL N DAKOTA HAD SPREAD INTO FAR WRN UPPER MI WITH MAINLY ONLY
HIGH CLOUDS TO THE EAST.
MODELS WERE CONSISTENT IN TAKING THE DAKOTAS MID LEVEL LOW TO THE SE
TOWARD THE OH VALLEY BY TUE EVENING WITH BEST Q-VECT CONV AND
WAA/ISENTROPIC LIFT STAYING SE OF UPPER MI CLOSER TO THE TRACK OF
THE LOW AND ASSOC INVERTED SFC TROUGH. SO...MUCH OF THE CWA SHOULD
SEE LITTLE OR NO SYNOPTIC SCALE PCPN. CHANCE POPS STILL WERE
RETAINED OVER THE WEST WITH LITTLE IF ANY SNOW ACCUMULATION EXPECTED.
HOWEVER...HIGHER RES MODELS SUGGEST THAT AS NE FLOW STRENGTHENS AND
BECOMES MORE CYCLONIC PULLING 925-800 MB MOISTURE NE OF LAKE
SUPERIOR BACK INTO THE AREA...THE POTENTIAL FOR LAKE ENHANCED SNOW
INTO N CNTRL UPPER MI WILL INCREASE. WITH TEMPS NEAR THE 900 MB
INVERSION HEIGHT (NEAR 3K FT) ONLY AROUND -12C...BOTH INSTABILITY
AND SLR VALUES WILL BE MARGINAL FOR SIGNFICANT SNOW.
HOWEVER...UPSLOPE FLOW INTO THE HIGHER TERRAIN SHOULD BE ENOUGH TO
SUPPORT -SHSN BY TUE AFTERNOON WITH ACCUMULATIONS LESS THAN A HALF
INCH.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 356 PM EST MON MAR 4 2013
THE GENERALLY QUIET MARCH WEATHER CONTINUES THROUGH MUCH OF THE
LONG TERM PERIOD.
EXPECT SOME SNOW SHOWERS TO BE AFFECTING THE AREA
TUESDAY NIGHT INTO WEDNESDAY AS A LINGERING SURFACE TROUGH IS LEFT
BEHIND THE CLIPPER SYSTEM SLIDING TO THE SOUTH OF THE AREA TODAY
THROUGH TUESDAY. ALTHOUGH THE SYSTEM WILL BE TO THE SOUTH OF THE
AREA...DEEPER MOISTURE ROTATING WEST FROM THE LOW NEAR THE NEW
ENGLAND STATES WILL PROVIDE ENOUGH MOISTURE FOR SNOW TO DEVELOP
TUESDAY AFTERNOON INTO TUESDAY NIGHT. H850 TEMPERATURES OF -11C OVER
THE WEST AND -8C OVER THE EAST SHOULD BE COLD ENOUGH FOR LAKE
ENHANCEMENT...ESPECIALLY WITH THE ABUNDANT MOISTURE. IN
ADDITION...WITH THE LINGERING SURFACE TROUGH SLOWLY SLIDING ACROSS
THE AREA AND THE LEFTOVER NORTHERN STREAM SHORTWAVE AND ASSOCIATED
HEIGHT FALLS MOVING EAST ACROSS THE NORTHERN HALF OF THE
CWA...EXPECT A PERIOD OF LIGHT SNOW SHOWERS FOR THE WEST/CENTRAL
UPPER MICHIGAN TUESDAY NIGHT INTO WEDNESDAY. CYCLONIC
NORTH-NORTHEAST SFC-925 WINDS WOULD FAVOR THE NORTHWEST HALF OF
UPPER MICHIGAN FOR THE POPS. DID BUMP POPS UP SOME OVER THE
KEWEENAW FOR LATE TUESDAY NIGHT INTO WEDNESDAY MORNING...AS THERE
IS ADDITIONAL FORCING ALOFT FROM THE SHORTWAVE. SNOW RATIOS LOOK TO
BE ON THE LOW SIDE FOR MOST OF THE AREA...AT OR BELOW 10-1...SINCE
THE CLOUDS STRUGGLE TO GET ABOVE -10C. THERE IS A POTENTIAL FOR
SLIGHTLY HIGHER RATIOS OVER THE KEWEENAW DUE TO THE SYNOPTIC
FORCING...TOWARDS 15-1...BUT BEST FORCING LOOKS TO BE ABOVE THE DGZ
IN THAT AREA TO KEEP RATIOS FROM GETTING TOO HIGH. THE TROUGH
SLIDING EAST ON WEDNESDAY WILL TRANSITION THE LINGERING CLOUDS/SNOW
TO THE NORTHWEST WIND FAVORED LOCATIONS. MOST LOCATIONS WILL SEE A
LIGHT DUSTING OF SNOW BY WEDNESDAY EVENING...BUT SLIGHTLY HIGHER
AMOUNTS OF 1-2 INCHES ARE POSSIBLE OVER THE KEWEENAW AND THE HIGHER
TERRAIN OF MARQUETTE COUNTY.
THIS LINGERING TROUGH AND SHORTWAVE WILL SLIDE TO THE EAST OF THE
AREA ON WEDNESDAY...AS HIGH PRESSURE SLIDES EAST AND OVER THE UPPER
GREAT LAKES FOR WEDNESDAY NIGHT INTO THURSDAY BEFORE PUSHING EAST
ON FRIDAY. THIS HIGH SHOULD LEAD TO GRADUALLY DECREASING CLOUDS
DURING THAT PERIOD. ONCE AGAIN...THE POTENTIAL IS THERE FOR SOME
LINGERING FLURRIES OR STRATOCU STUCK BELOW THE INVERSION AROUND
2.5KFT. WILL PROBABLY BE SOMETHING SIMILAR TO THIS MORNINGS CLOUDS
FOR LOCATIONS FAVORED BY NORTH-NORTHWEST FLOW WEDNESDAY NIGHT INTO
THURSDAY. BUT WITH WINDS WEAKENING UNDER THE HIGH AND INCREASING DRY
AIR MOVING IN...WOULD THINK THAT THE LOW CLOUDS WOULD BE NEARLY GONE
ON THURSDAY NIGHT. WEDNESDAY NIGHT LOWS ARE TRICKY...SINCE THEY WILL
DEPEND ON WHERE THE CLOUDS ARE LOCATED. WHERE SKIES ARE
CLEAR...LIGHT WINDS AND PWAT VALUES TOWARDS 50 PERCENT OF NORMAL
WOULD LEAD TO GOOD RADIATIONAL COOLING. UPPER RIDGE WILL ALSO BUILD
OVER THE AREA DURING THIS TIME AND PRODUCE GRADUALLY WARMING
TEMPERATURES ALOFT...ESPECIALLY HEADING INTO THE WEEKEND AS
SOUTHERLY FLOW INCREASES WITH THE HIGH SLIDING TO THE EAST OF THE
AREA. THIS SHOULD TRANSITION THE AREA AWAY FROM THE BELOW NORMAL
TEMPERATURES THAT WE HAVE BEEN IN AND MORE NORMAL OR SLIGHT ABOVE
NORMAL HIGHS.
AS FOR PRECIPITATION HEADING INTO THE WEEKEND...THE CHANCES ALL
DEPEND ON THE STRENGTH OF THE UPPER RIDGE. THE FIRST SHORTWAVE WILL
RIDE UP THE UPPER RIDGE ON FRIDAY AND HEAD NORTHEAST TOWARDS JAMES
BAY ON FRIDAY NIGHT. 06Z GFS AND 00Z GEM HAVE IT FARTHER TO THE
SOUTHEAST AND MOVING ACROSS LAKE SUPERIOR...WHILE THE 00Z ECMWF
KEEPS IT WELL TO THE NORTHWEST IN ONTARIO. WITH THE SURFACE LOW
WELL TO THE NORTH OF THE AREA...SHOULD SEE A SURFACE TROUGH
PUSHING THROUGH THE AREA ON LATE FRIDAY NIGHT INTO SATURDAY. MODELS
VARYING ON TIMING AND AMOUNT OF MOISTURE ASSOCIATED WITH THE
SHORTWAVE AND THEN THE SURFACE TROUGH. THEY DO AGREE THAT DEEP
MOISTURE FOR WIDESPREAD SNOW SEEMS MARGINAL AND MORE LIKELY SEE
ISOLATED TO SCATTERED SNOW SHOWERS DURING THAT PERIOD.
UNCERTAINTY GROWS AFTER SATURDAY...AS THERE ARE LARGE MODEL AND
RUN-TO-RUN DIFFERENCES IN THE HANDLING OF THE UPPER LOW OVER THE
SOUTHWESTERN CONUS AND HOW THE NORTHERN AND SOUTHERN JET STREAMS
PHASE AS THE TROUGH SLIDES EAST. MODELS HAVE A DIFFICULT TIME WITH
PHASING SYSTEMS A DAY OR TWO OUT...SO DON/T HAVE ANY CONFIDENCE TO
GO MORE THAN A CONSENSUS CHANCE POPS FOR MONDAY WITH THE LOW MOVING
THROUGH THE GREAT LAKES. DESPITE THESE DIFFERENCES...BOTH THE LONGER
RANGE GFS/ECMWF DO SHOW THE UPPER TROUGH REESTABLISHING OVER THE
CENTRAL CONUS BY THE MIDDLE OF NEXT WEEK. THIS PRODUCES A POTENTIAL
FOR ANOTHER BELOW NORMAL TEMPERATURE PERIOD FOR THE UPPER GREAT
LAKES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1217 AM EST TUE MAR 5 2013
EXPECT SNOW SHOWERS TO BEGIN LATE TONIGHT AT ALL THREE TAF SITES.
LOW PRESSURE WILL MOVE FROM THE NORTHERN PLAINS INTO THE OHIO VALLEY
OVERNIGHT AND TUESDAY. THIS WILL BRING SOME HIGH-MID LEVEL CLOUDS TO
THE AREA OVERNIGHT...AND LIMITED SUPPORT FOR SNOW AT IWD TONIGHT.
OTHERWISE...THIS SYSTEM WILL ALLOW SURFACE WINDS TO REMAIN EAST TO
NORTHEASTERLY INTO TOMORROW. AS A RESULT...LAKE EFFECT SNOW SHOWERS
WILL DEVELOP LATE TONIGHT AND LAST THROUGH TUESDAY AT ALL THREE
SITES. OVERALL...CONDITIONS SHOULD BE VFR THROUGH THE EARLY EVENING
TONIGHT...THEN DETERIORATE TO LOW END MVFR TOWARDS MORNING. LOW END
MVFR WILL BE THE RULE THROUGH THE REMAINDER OF THE DAY
TUESDAY...ESPECIALLY TOWARDS THE EVENING HOURS. SOME OF THE MODEL
GUIDANCE SUGGESTS IFR CONDITIONS DEVELOPING AFTER 3Z...HOWEVER
CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN THE TAF AT THIS TIME.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EST MON MAR 4 2013
AS LOW PRESSURE OVE THE DAKOTAS SLIDES TO THE SE...NE WINDS TO 30
KTS ARE EXPECTED MON NIGHT THROUGH TUE...ESPECIALLY OVER THE WRN
THIRD OF THE LAKE WHERE LOW LEVEL CONV IS STRONGEST. NORTH WINDS TO 25 KTS
CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY WINDS AND COLDER
TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT TIMES THROUGH
WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS LATER
WEDNESDAY INTO FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...MCD
MARINE...JLB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1202 AM CST TUE MAR 5 2013
.UPDATE...
THE TIMING OF THE WIND ADVISORY IN SPOTS AS ORD HAS JUMPED TO
ADVISORY CRITERIA THE PAST HOUR AND HRRR IS INDICATING THESE
STRONG GUSTY WINDS WILL NOT RELAX MUCH...IF ANY...OVERNIGHT. OTHER
THAN INCREASING THE WIND FORECAST FOR THE OVERNIGHT HOURS...THE
REMAINDER OF THE FORECAST APPEARS TO BE ON TRACK AND NO ADDITIONAL
CHANGES WERE NECESSARY WITH THE UPDATE.
&&
SHORT TERM...(TONIGHT THROUGH TUESDAY) ISSUED AT 307 PM CST MON
MAR 4 2013
FOCUS DURING THE SHORT TERM PERIODS IS ON WINDS.
WATER VAPOR IMAGERY INDICATES A CLOSED UPPER LOW PRESSURE SYSTEM IN
THE WESTERN DAKOTAS...SHORTWAVE RIDGING IN THE PACIFIC NORTHWEST
WITH AN UPSTREAM UPPER LOW STILL OUT IN THE PACIFIC. AT THE SURFACE
LOW PRESSURE CENTERS WERE LOCATED IN SOUTH CENTRAL NORTH DAKOTA AS
WELL AS EASTERN OK. THE INITIAL COLD FRONTAL BOUNDARY WHICH CROSSED
OUR REGION OVERNIGHT WAS LOCATED FM EASTERN KS TO THE OK
PANHANDLE...WITH THE SECONDARY STRONGER COLD FRONT STRETCHING FROM
WESTERN SD TO SW NEB EARLY THIS AFTN.
NORTHWEST WINDS WERE STEADY/GUSTY ESPECIALLY THIS MORNING IN A TIGHT
PRESSURE GRADIENT FOLLOWING THE PASSAGE OF COLD FRONT
OVERNIGHT/COLD FRONT NUMBER ONE. THE SFC GRADIENT HAS RELAXED SOME
THIS AFTN WITH SOME DECREASE IN WIND SPEEDS NOTED. THE DEEPER
MIXING TODAY HAS ALLOWED TEMPS TO CLIMB TO THE MID/UPPER 40S. RADAR
RETURNS HAVE BEEN PICKING UP ON MID CLOUD COVER BUT RETURNS HAVE
ENHANCED THE LAST SEVERAL SCANS. ISOLATED SHOWERS/SPRINKLES ARE
NOT OUT OF THE QUESTION ESPECIALLY ACROSS THE SOUTHERN HALF OF OUR
CWA IN PRESENCE OF MID LEVEL FRONTOGENESIS AND LIFT ENHANCED AS
ENERGY ROUNDS BASE OF TROUGH...WHILE UPPER LOW TRANSLATES SE. LOW
POPS FOR ISOLATED -SHRA HAVE BEEN MAINTAINED THRU THE EVENING AND
FIRST PART OF THE NIGHT.
HEADING INTO TONIGHT...A STRONGER COLD FRONT/COLD FRONT NUMBER TWO
SWEEPS SOUTHEAST AFTER DARK WITH 6HR PRESSURE RISES AVERAGING 5 TO
7MB INITIALLY BEHIND THE FRONT. FORECAST SOUNDINGS MIX OUT LLVL
INVERSION AFTER 06Z AND ALTHOUGH COULD SEE SOME STRONG WINDS WITH
FROPA...LOOKING AT MORE SUSTAINED GUSTY WINDS HEADING INTO THE
OVERNIGHT TIME FRAME ON THE BACK SIDE OF THE UPPER LOW WHICH IS
PROGGED TO BE NEAR NE NEB 12Z TUESDAY. WITH INCREASING NW WINDS
TONIGHT AND WINDS REMAINING STRONG/GUSTY THRU AT LEAST THE FIRST
PART OF THE DAY ON TUESDAY...WILL GO AHEAD WITH A WIND ADVISORY
FOR OUR NORTHERN/EASTERN ZONES WHERE GRADIENT WILL BE TIGHTER IN
PROXIMITY TO THE LOW AND FORECAST SOUNDINGS INDICATE MIXING
BETWEEN H825 AND H85 WITH WINDS AT THE TOP OF THE LAYER AOA 40KTS.
SREF WIND PROBS INDICATE DECENT CHCS FOR REACHING WIND ADV
CRITERIA AND MOS GUIDANCE ALSO INDICATES POTENTIAL FOR NEAR/ABOVE WIND
ADV WINDS FOR SEVERAL HOURS. WIND SPEEDS IN OUR WESTERN ZONES MAY
DROP OFF EARLIER IN AFTN THAN HEADLINE INDICATES BUT PREFER TO
HAVE A ROW OF COUNTIES AS A BUFFER ACROSS OUR WEST/SOUTH ATTM. IN
CAA TUESDAY...GENERALLY EXPECT HIGHS TO AVERAGE IN THE MID/UPPER
30S. PCPN CHCS TUESDAY LOOK TO FAVOR LOCATIONS EAST OF OUR CWA
WHERE SOME FLURRIES/LIGHT SNOW SHOWERS ARE NOT OUT OF THE
QUESTION.
LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 307 PM CST MON
MAR 4 2013
TUESDAY NIGHT THROUGH MONDAY. MAIN FORECAST CONCERNS
WILL BE PRECIPITATION CHANCES FOR THE WEEKEND AND TEMPERATURES
THROUGH THE PERIOD.
AN UPPER LEVEL RIDGE IN THE WESTERN CONUS WILL DRIFT TO THE EAST
TUESDAY NIGHT THROUGH THURSDAY NIGHT. DURING THIS TIME A SURFACE
HIGH WILL MOVE TO THE EAST TUESDAY NIGHT WITH A TIGHTENING SURFACE
PRESSURE GRADIENT AS A SURFACE LOW DEVELOPS TO THE WEST. SOUTH WINDS
WILL INCREASE ACROSS THE AREA ON WEDNESDAY AND WILL CONTINUE THROUGH
THURSDAY NIGHT. EXPECT SOME BREEZY CONDITIONS...BUT MOST MODELS ONLY
HAVE 30 TO 35 KNOTS AT 850 MB SO DO NOT EXPECT VERY STRONG WINDS.
WITH THE SOUTH WINDS...SOME WARM ADVECTION AND THE UPPER RIDGE
MOVING THROUGH THE AREA...TEMPERATURES WILL BE WARMER AGAIN WITH
WARMER TEMPERATURES ON THURSDAY THAN WEDNESDAY.
THURSDAY NIGHT INTO FRIDAY THERE IS AN UPPER LEVEL WAVE THAT MOVES
INTO THE RIDGE AND THE SURFACE LOW AND COLD FRONT MOVE INTO THE
AREA. EXPECT AN INCREASE IN THE CLOUDS BUT TEMPERATURES WILL BE A
LITTLE COOLER IN THE NORTH BUT ABOUT THE SAME FOR THE SOUTH.
THE MODELS TAKE ON SOME FAIRLY SIGNIFICANT DIFFERENCES FOR THE
EXTENDED PERIOD. SOME OF THE DIFFERENCES START EVEN ON FRIDAY. AN
UPPER LOW PRESSURE SYSTEM WILL BE MOVING INTO THE PLAINS AND BRING A
CHANCE FOR PRECIPITATION TO THE AREA FROM FRIDAY NIGHT INTO MONDAY.
THE GFS IS MORE PROGRESSIVE WHILE THE LATEST RUN OF THE ECMWF SLOWS
THE CLOSED LOW DOWN AND LINGERS IT TO THE WEST WHILE THE GFS PUSHES
IT THROUGH INTO THE GREAT LAKES BY MONDAY EVENING. EXPECT THERE TO
BE PRECIPITATION STARTING FRIDAY NIGHT. THE BEST CHANCE WILL BE
SATURDAY AND SATURDAY NIGHT. HAVE LESS CHANCES FOR SUNDAY THROUGH
MONDAY. THE NEXT QUESTION WILL BE PRECIPITATION TYPE. TEMPERATURES
ARE FAIRLY WARM FRIDAY NIGHT THROUGH SUNDAY AND THERE IS A LITTLE
INSTABILITY SO HAVE WENT WITH SHOWERS. THE GFS HAS UP TO 300 J/KG.
THERE COULD BE AN ISOLATED LIGHTNING...BUT IT IS JUST A SMALL CHANCE
AND WITH THE MODELS HAVING SO MANY DIFFERENCES WILL JUST KEEP
SHOWERS. BY SUNDAY NIGHT THERE IS SOME COOLER AIR MOVING INTO THE
AREA AND THERE COULD BE SOME RAIN OR SNOW MIXED FOR SUNDAY NIGHT
INTO MONDAY.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1150 PM CST MON MAR 4 2013
WHILE CONFIDENCE IS HIGH IN UNRESTRICTED VISIBILITY THROUGH THE
PERIOD...THE PRIMARY MODIFICATION FROM PREVIOUS TAF ISSUANCE
INVOLVES THE INTRODUCTION OF A HIGH-END MVFR CEILING FOR UP TO A
7-HOUR PERIOD FROM 09Z TO 16Z THIS MORNING...AS STRATUS ADVECTS
SOUTHWARD OUT OF SOUTH DAKOTA ON THE BACK SIDE OF A STRONG MID
LEVEL LOW PRESSURE SYSTEM. THIS MVFR CEILING IS NOT A CERTAINTY BY
ANY MEANS...AS KGRI COULD BE VERY CLOSE TO ITS FAR WESTERN
EDGE...AND POTENTIALLY MISS OUT...SO TRENDS WILL BE MONITORED
CLOSELY. A FEW FLURRIES ARE POSSIBLE WITH THIS STRATUS...BUT HAVE
NOT INCLUDED IN THE TAF. ASSUMING ANY LOW CLOUDS VACATE BY MID-
DAY...THE LATTER 12 HOURS OF THE PERIOD SHOULD FEATURE ESSENTIALLY
CLOUD-FREE SKIES. OTHERWISE...STRONG NORTHWEST WINDS WILL REMAIN
AN ISSUE ESPECIALLY THROUGH THE NEXT 18 HOURS...WITH SUSTAINED
SPEEDS GENERALLY RANGING FROM AT LEAST 20-25 KT AND FREQUENTLY
GUSTING AT LEAST 29-35KT...AND GENERALLY PEAKING IN INTENSITY
BETWEEN SUNRISE AND NOON. A STEADY DECREASE IN WIND SPEEDS WILL
TAKE PLACE THROUGH THE LATE AFTERNOON/EVENING...AND EASING BELOW
10KT AFTER SUNSET.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 4 AM TO 3 PM CST TUESDAY FOR NEZ041-048-049-
062>064-074>077.
WIND ADVISORY UNTIL 3 PM CST TUESDAY FOR NEZ039-040-046-047-061.
KS...NONE.
&&
$$
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1118 PM CST MON MAR 4 2013
.UPDATE...
LIGHT PRECIPITATION WILL CONTINUE TO MOVE OUT OF SOUTHWEST IOWA
AND FAR SOUTHEAST NEBRASKA THROUGH ABOUT 2 AM. ANY SNOW FALLING
WILL REDUCE VISIBILITIES FOR A TIME...BUT WITH TEMPERATURES
REMAINING ABOVE FREEZING WHILE PRECIPITATION IS FALLING...SHOULD
NOT SEE ANY ACCUMULATION. THEN STRONG NORTHWEST WINDS WILL SPREAD
ACROSS THE AREA BEFORE SUNRISE...WITH GUSTS OVER 35KT LIKELY
BEFORE 12Z IN NORTHEAST NEBRASKA. STRONG WINDS WILL OVERSPREAD THE
REST OF EASTERN NEBRASKA AND SOUTHWEST IOWA...AND AN EXPANSION OF
WIND ADVISORY MAY BE NEEDED WITH MORNING FORECAST PACKAGE.
&&
.AVIATION...06Z TAFS FOR KOFK...KLNK AND KOMA.
BAND OF LIGHT SNOW WAS MOVING EAST OF THE KOMA AREA BEFORE
06Z...SO MAINLY VFR CONDITIONS ARE EXPECTED THROUGH SUNRISE. A
STRONG LOW PRESSURE SYSTEM WILL INCREASE NORTHWEST WINDS INTO THE
25 TO 35KT RANGE AT ALL TAF SITES BY MID MORNING. MVFR CIGS NEAR
FL025 ARE LIKELY THROUGH THE DAY AS WELL. THE CLOUDS AND WINDS
WILL DECREASE IN COVERAGE/INTENSITY LATE IN THE AFTERNOON.
DERGAN
&&
.PREV DISCUSSION... /ISSUED 335 PM CST MON MAR 4 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY
THE PRIMARY FORECAST CONCERNS DURING THIS PERIOD ARE PCPN AND WINDS
TONIGHT...WINDS ON TUESDAY AND POTENTIAL FOR CLOUD COVER FOR TUESDAY
NIGHT.
CLOSED LOW AT 500 MB WHICH WAS OVER EXTREME EASTERN MONTANA AT 12Z
WILL CONTINUE TO DIVE SOUTHEAST TONIGHT...REACHING THE BORDER AREA
OF SOUTH DAKOTA/MINNESOTA/IOWA BY 12Z TUESDAY AND THEN SOUTHERN
ILLINOIS BY 00Z WEDNESDAY. SURFACE ANALYSIS EARLY THIS AFTERNOON
SHOWED ONE LOW PRESSURE CENTER OVER SOUTH CENTRAL NORTH DAKOTA AND
ANOTHER OVER OKLAHOMA. AN INVERTED TROF EXTENDED NORTHWARD FROM
THE SOUTHERN LOW. NORTHERN LOW WILL PUSH SOUTHEAST AND WEAKEN
OVERNIGHT. FAIRLY TIGHT PRESSURE GRADIENT OVER THE AREA ALONG WITH
DECENT DOWNWARD MOMENTUM TRANSFER SHOULD RESULT IN GUSTY WINDS
LATER TONIGHT AND INTO TUESDAY. WILL LEAVE PREVIOUSLY ISSUED WIND
ADVISORY IN PLACE BUT EXTEND IT UNTIL 21Z. THIS CAN BE CANCELED IS
WINDS DECREASE EARLIER. ALSO ISSUED ANOTHER WIND ADVISORY SEGMENT
TO THE SOUTHEAST OF PREVIOUS ADVISORY FROM 8 AM TO 3 PM
TUESDAY...AS STRONGER WINDS OVERSPREAD MORE OF THE AREA.
RADAR ECHOES HAVE BEEN INCREASING TO OUR WEST...WITH SOME LIGHT SNOW
REPORTED IN PARTS OF SOUTHWEST NEBRASKA. RECENT HRRR AND RAP13 MODEL
RUNS INDICATE SOME PCPN WILL DEVELOP OVER ABOUT THE SOUTHEAST HALF
OF THE FORECAST AREA THIS EVENING...IN ASSOCIATION WITH 500-300 MB
Q VECTOR DIVERGENCE AND ELEVATED FRONTOGENESIS. RAP13 PCPN
AMOUNTS SEEM OVERDONE...BUT SCENARIO IS ALSO SUPPORTED BY 18Z NAM.
ON TUESDAY...FAIRLY TIGHT PRESSURE GRADIENT IS IN PLACE DURING THE
MORNING BUT THIS RELAXES IN THE AFTERNOON. THERE IS SOME SMALL
POTENTIAL FOR LIGHT SNOW TUESDAY...MAINLY FOR ABOUT THE NORTHEAST
ONE THIRD OF THE FORECAST AREA...BUT CHANCES ARE MUCH HIGHER FARTHER
TO THE EAST OF OUR AREA.
OTHERWISE...LOOK FOR MAINLY DRY CONDITIONS TUESDAY NIGHT AS HIGH
PRESSURE BUILDS IN. SOME MODELS SHOW LOW LEVEL MOISTURE MOVING INTO
THE AREA FROM THE NORTH...SO WILL HAVE TO WATCH THAT. FOR NOW...
HAVING CLEARING SKIES. THAT SURFACE RIDGE WILL PUSH OFF TO THE EAST
WEDNESDAY THROUGH THURSDAY WITH INCREASING SOUTH/SOUTHEAST WINDS...
MODERATING TEMPERATURES AND MAINLY DRY CONDITIONS.
MILLER
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
CONFIDENCE IS INCREASING THAT THE UPPER LEVEL LOW THAT WILL DIVE
INTO THE SOUTHWEST CONUS ON WED/THU WILL MOVE INTO THE PLAINS AT
SOME POINT NEXT WEEKEND. THE ECMWF/GEM HAVE REMAINED VERY CONSISTENT
OVER THE PAST COUPLE OF DAYS WHILE THE OPERATIONAL GFS HAS VARIED
WILDLY FROM THE 00Z/04 TO 12Z/O4 RUNS. THUS WILL LEAVE MUCH HEAVIER
ON THE EC/GEM/EC ENSEMBLE SOLUTIONS FOR THE TRACK OF THIS SYSTEM.
AHEAD OF THE SYSTEM/COLD FRONT WE SHOULD SEE A NICE DAY ON FRIDAY
WITH HIGHS ABOVE SEASONAL AVERAGES. THE COLD FRONT THEN MOVES
THROUGH THE FA ON THE WEEKEND WITH SLIGHTLY COOLER AIR MOVING INTO
THE REGION. THE GFS...ALTHOUGH CLOSER TO THE EC WITH THE 12Z/04
RUN...IS STILL TO FAST IN BRINGING PRECIP TO THE AREA. WILL HOLD
ONTO SOME POPS IN THE SW ON FRI NIGHT...BUT IT WILL LIKELY BE SAT OR
MAYBE EVEN SAT NIGHT BEFORE WE SEE THE BULK OF THE PRECIP ASSOCIATED
WITH THE UPPER LEVEL LOW HEAD INTO THE PLAINS.
THE EC IS VERY WARM FOR THIS SYSTEM AND WOULD HAVE LIMITED CHANCE OF
ANY FROZEN PRECIP AT ALL FOR OUR FA...AND WE WILL TREND THE FORECAST
THIS WAY. HAVE INCREASED OVERNIGHT LOWS AS WELL AS HIGHS A TOUCH FOR
MOST AREAS. REMOVED FZRA MENTION AND WENT WITH A RA/SN MIX IN THE
FAR NORTH AND OTHERWISE JUST RA OVER THE SRN 2/3RD OF THE FA. IT IS
IMPORTANT TO NOTE THAT THE FORECAST WILL HAVE CHANCES OF PRECIP FOR
SEVERAL PERIODS...BUT THIS MORE REFLECTS THE UNCERTAINTY IN THE
TIMING MORE THAN WE WILL HAVE CONTINUOUS RAIN OVER A 48 HOUR
PERIOD.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 8 AM TO 3 PM CST TUESDAY FOR NEZ015-032>034-
042>045-050-051-065-066-078.
WIND ADVISORY UNTIL 3 PM CST TUESDAY FOR NEZ011-012-016>018-030-
031.
IA...WIND ADVISORY FROM 8 AM TO 3 PM CST TUESDAY FOR IAZ043.
&&
$$
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
122 AM EST TUE MAR 5 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL MIGRATE ACROSS THE AREA EARLY
TODAY...BEFORE YIELDING TO LOW PRESSURE TRACKING EASTWARD FROM THE
MID MISSISSIPPI VALLEY ALONG THE OHIO RIVER. AS THE LOW REACHES
THE NORTH-CENTRAL APPALACHIANS THIS EVENING...A SECONDARY LOW WILL
DEVELOP OVER THE VIRGINIA/CAROLINA PIEDMONT LATE TONIGHT AND MOVE
SLOWLY NORTHEAST TOWARD THE DELMARVA PENINSULA ON WEDNESDAY BEFORE
SHIFTING OFF THE MID-ATLANTIC COAST WEDNESDAY NIGHT. THIS COMPLEX
SYSTEM WILL LIKELY BRING MODERATE TO HEAVY SNOW TO PARTS OF SOUTH-
CENTRAL PENNSYLVANIA THROUGH MID-WEEK.
&&
.NEAR TERM /UNTIL 1 PM THIS AFTERNOON/...
IR SATL TRENDS SHOW LOW CLOUDS SINKING SWWD OVR THE NERN 1/2 OF
THE CWA...REACHING A DUJ-UNV-MUI LINE AS OF 06Z. THE SW 1/2 OF THE
CWA IS MAINLY CLEAR WITH MID-HIGH CLOUDS GRADUALLY INCREASING OVR
THE FAR SW CORNER OF PA. HI-RES NAM/RUC ARE AT ODDS WITH THE
EVOLUTION OF THE LOW CLOUD COVER...WITH THE RUC INDICATING A MORE
PESSIMISTIC OUTCOME THRU THE AM HOURS. IN GENERAL KEPT SOME
CONTINUITY WITH THE PREV FCST AND WENT WITH A GRADUAL DECREASE IN
THE LOW CLOUDS THRU THE LATE AM BEFORE MID-HIGH CLOUDS WORK INTO
THE AREA FROM THE SW BY THE MID-LATE AFTN. CONSENSUS MDL/MOS BLEND
SHOWS TEMPS REACHING THE LOW-MID 30S NORTH/UPPER 30S-LOW 40S SOUTH
BY 18Z. MAIN FOCUS WILL BE ON THE UPPER LOW DIVING SEWD FROM THE
NRN PLAINS...SPAWNING SFC LOW PRES IN THE LWR OH VLY BY 12-15Z.
&&
.SHORT TERM /1 PM THIS AFTERNOON THROUGH 6 PM WEDNESDAY/...
THE NRN STREAM LOW ABDICATES TO THE BETTER MOISTURE IN THE MID MS
VALLEY...AND LOW DEVELOPS OVER KPAH EARLY IN THE DAY. THIS LOW
SHOULD RIDE UP THE OH VALLEY INTO SRN OH/ERN KY BY DAY/S END.
STRONG/HIGHLY ANOMALOUS ESE FLOW WILL RAPIDLY DEVELOP OVER THE MID
ATLANTIC STATES. THE NOSE OF THE FASTEST LOW/MID LVL FLOW WILL
EVENTUALLY POINT INTO SC PA. MAIN/PRIMARY LOW STARTS TO FILL AND
SECONDARY LOW JUST STARTING TO DEVELOP OVER VA/NC BORDER AT THE
END OF THE PD. ALMOST ALL GUIDANCE POINTS TO THE FIRST FLAKES
STARTING AROUND SUNSET IN SOMERSET CO. WILL HOLD POPS NEAR ZERO
ELSEWHERE FOR THE DAYTIME.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
EXTENDED WATCH NORTH INTO MIFFLIN...JUNIATA...PERRY...DAUPHIN AND
LEBANON COUNTIES LATEST GEFS AND SREF RUNS. STILL SIGNIFICANT
UNCERTAINTY IN NORTHWARD EXTEND OF SNOW BANDS WITH UPCOMING
SYSTEM...BUT THERE IS ENOUGH POTENTIAL FOR WARNING CRITERIA SNOWS
IN THIS AREA TO WARRANT A NORTHWARD EXTENSION IN THE WATCH. THIS
PUTS CENTRE COUNTY AND THE STATE COLLEGE AREA ON THE SOUTHERN EDGE
OF AREA OUTSIDE OF THE WATCH...BUT IT WILL BE A CLOSE CALL
LOCALLY. GEFS U-WIND ANOMALIES -3 TO -4 OVER AREA AND STRONGER TO
SE. VERY IMPRESSIVE.
PREVIOUS DISCUSSION FOLLOWS...
POTENTIAL FOR MIDWEEK WINTER STORM CONTINUES TO INCREASE AS MODELS
REMAIN CONSISTENT ON AN UPPER LOW TRACK ACROSS VA/NC BORDER TUE
NIGHT INTO WED. QPF BETWEEN MODELS COMING MORE INTO LINE AS
GRADIENT CONTINUES TO SLOWLY SHARPEN...WITH HIGHER QPFS THAT HAVE
BEGUN TO NOSE INTO SOUTHERN TIER REMAINING THERE IN 12Z RUNS...SO
POTENTIAL FOR HEAVY SNOW REMAINS. WITH ONSET OF SNOW ABOUT 26 HRS
AWAY IN THE SW /23Z TUE/...ADJUSTED HEADLINES TO UPGRADE OLD WATCH
TO A WARNING AND ADDED A RIBBON OF WINTER STORM WATCH FOR NEXT
LINE NORTH AND THEN ALONG REMAINDER OF SOUTHERN TIER WHERE
POTENTIAL DOES EXIST FOR 6+ INCHES...BUT TOTALS STILL REMAIN QUITE
FUZZY IN THAT REGION MAKING IT A TRICKY FORECAST FOR SOUTHERN AND
CENTRAL MTNS. INCREASING CONFIDENCE IN HIGHER SNOW AMOUNTS FOR SW
COUNTIES.
A BLEND OF GUIDANCE REMAINS BEST CHOICE...WITH NAM SPLITTING THE
DIFFERENCE BETWEEN THE NORTHERLY CURVING GFS AND EASTWARD
PROGRESSING ECMWF. EXPECT LIGHT SNOW TO DEVELOP DURING THE LATE
AFTERNOON HOURS OVER THE LAUREL HIGHLANDS WITH LITTLE ACCUMS EARLY
ON GIVEN WARM AFTERNOON SURFACE TEMPS. HIGHS WILL RANGE FROM THE
UPPER 30S OVER THE LAURELS AND NORTHWEST MOUNTAINS TO THE MID 40S
OVER THE SOUTHEAST.
A RATHER VIGOROUS SYSTEM WILL TRACK FROM THE LOWER OHIO VALLEY TO
THE MID ATLANTIC COAST WHILE A HIGHLY CYCLONIC AND STRONG 120+ KT
300 MB JET SUPPORTS THE LIKELIHOOD OF AN EXTENDED...18-24 HR
PERIOD OF ENHANCED SNOWFALL NEAR AND SOUTH OF THE MASON DIXON
LINE. SOME LIGHT SNOWFALL MAY EXTEND NORTHWARD TO THE CENTRAL
MOUNTAINS...BUT DO NOT EXPECT ANY ACCUMS NORTH OF I-80 AT THIS
TIME.
BEING ON THE NORTHERN EDGE OF SIGNIFICANT SNOWFALL WILL MAKE FOR
A CONTINUED CHALLENGING CALL OVER THE NEXT 24 TO 36 HOURS. A FAIR
AMOUNT OF CHANGE IN THE TRACK AND STRENGTH OF THE STORM IS STILL
POSSIBLE...EVEN AT THIS SHORT RANGE.
FOLLOWING THE STORM ON THURSDAY...A CHILLY AND RATHER GUSTY
NORTHERLY FLOW ARRIVES WITH ISOLATED TO SCATTERED MTN SNOW
SHOWERS...BEFORE HEIGHTS RISE AND DAYTIME TEMPS MODERATE TO NEAR
NORMAL BY FRIDAY AND SATURDAY. A FAST MOVING AND RELATIVELY
FLAT/WEAK NRN STREAM SHORTWAVE WILL TRACK ACROSS THE GREAT LAKES
AND NRN PENN OVER THE WEEKEND /WITH TIMING DIFFS BETWEEN
MODELS/...POSSIBLY ACCOMPANIED BY A FEW SHOWERS OF RAIN AND WET
SNOW UP NORTH. SOUTHERN PORTIONS OF PENN SHOULD STAY MAINLY DRY
THROUGH THE WEEKEND.
WARMING TREND CONTINUES INTO EARLY NEXT WEEK...WITH SIGNIFICANT
MODEL DIVERGENCE. BUT GENERAL PATTERN BRINGS INCREASED RIDGING
OVER EASTERN U.S. AS NEXT LOW PROGGED TO LIFT INTO GLAKES BY
MIDWEEK.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
THE LOW LEVEL MOISTURE HAS BACKED UP SLOWER...AS THE EXITING LOW
IS KEEPING NORTHWESTERLY FLOW THROUGH THE REGION. THE STRATOCU
DECK IS STARTING TO WORK BACK TO THE SOUTH...SO BACKED OFF ON THE
CLEARING THE IFR FROM BFD FOR A FEW HOURS AND MVFR CIGS AT IPT AND
UNV.
THESE CIGS WILL SLOWLY LIFT BY MORNING. EXPECT IFR CIGS AT BFD
OVERNIGHT...BEFORE BEGINNING TO CLEAR OUT BY 15Z. THE NW FLOW WILL
SHIFT AND LESSEN FOR IPT AND UNV OVER THE NEXT FEW HOURS. EXPECT
VFR CIGS BY 09Z AT THE LATEST...WITH AND REMAINING STRATOCU
PULLING NORTHWARD BY 14Z. THE MID AND HIGH CLDS WILL BUILD
NORTHWARD DURING THE AFT ON TUE... AS A COMPLEX STORM MOVES EAST
FROM THE PLAINS. AT THIS POINT...EXPECT NO SNOW PRIOR TO 00Z WED.
THE STORM SYSTEM WILL CONTINUE TO MOVE EASTWARD TUESDAY
NIGHT INTO WED. EXPECT SNOW ACROSS THE AREA TUESDAY NIGHT
INTO WED EVENING. SOME OF THE SNOW WILL BE ON THE HEAVY
SIDE...ESPECIALLY ACROSS THE SOUTHERN TAF SITES.
IMPROVING CONDITIONS FOR THU INTO SAT...AS HIGH PRESSURE
BUILDS EASTWARD.
OUTLOOK...
TUE NIGHT INTO WED EVENING...IFR AND MVFR WITH AREAS OF SNOW.
THU...MVFR/IFR -SHSN EARLY...OTHERWISE VFR.
FRI-SAT...VFR CONDITIONS AS HIGH PRESSURE BUILDS EASTWARD.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM EST
WEDNESDAY FOR PAZ033>035.
WINTER STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY
AFTERNOON FOR PAZ024>028-036-056-057-059-063>066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...DANGELO
LONG TERM...ROSS/RXR
AVIATION...CERU/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
111 AM EST TUE MAR 5 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL MIGRATE ACROSS THE AREA EARLY
TODAY...BEFORE YIELDING TO LOW PRESSURE TRACKING EASTWARD FROM THE
MID MISSISSIPPI VALLEY ALONG THE OHIO RIVER. AS THE LOW REACHES
THE NORTH-CENTRAL APPALACHIANS THIS EVENING...A SECONDARY LOW WILL
DEVELOP OVER THE VIRGINIA/CAROLINA PIEDMONT LATE TONIGHT AND MOVE
SLOWLY NORTHEAST TOWARD THE DELMARVA PENINSULA ON WEDNESDAY BEFORE
SHIFTING OFF THE MID-ATLANTIC COAST WEDNESDAY NIGHT. THIS COMPLEX
SYSTEM WILL LIKELY BRING MODERATE TO HEAVY SNOW TO PARTS OF SOUTH-
CENTRAL PENNSYLVANIA THROUGH MID-WEEK.
&&
.NEAR TERM /UNTIL 1 PM THIS AFTERNOON/...
IR SATL TRENDS SHOW LOW CLOUDS SINKING SWWD OVR THE NERN 1/2 OF
THE CWA...REACHING A DUJ-UNV-MUI LINE AS OF 06Z. THE SW 1/2 OF THE
CWA IS MAINLY CLEAR WITH MID-HIGH CLOUDS GRADUALLY INCREASING OVR
THE FAR SW CORNER OF PA. HI-RES NAM/RUC ARE AT ODDS WITH THE
EVOLUTION OF THE LOW CLOUD COVER...WITH THE RUC INDICATING A MORE
PESSIMISTIC OUTCOME THRU THE AM HOURS. IN GENERAL KEPT SOME
CONTINUITY WITH THE PREV FCST AND WENT WITH A GRADUAL DECREASE IN
THE LOW CLOUDS THRU THE LATE AM BEFORE MID-HIGH CLOUDS WORK INTO
THE AREA FROM THE SW BY THE MID-LATE AFTN. CONSENSUS MDL/MOS BLEND
SHOWS TEMPS REACHING THE LOW-MID 30S NORTH/UPPER 30S-LOW 40S SOUTH
BY 18Z. MAIN FOCUS WILL BE ON THE UPPER LOW DIVING SEWD FROM THE
NRN PLAINS...SPAWNING SFC LOW PRES IN THE LWR OH VLY BY 12-15Z.
&&
.SHORT TERM /1 PM THIS AFTERNOON THROUGH 6 PM WEDNESDAY/...
THE NRN STREAM LOW ABDICATES TO THE BETTER MOISTURE IN THE MID MS
VALLEY...AND LOW DEVELOPS OVER KPAH EARLY IN THE DAY. THIS LOW
SHOULD RIDE UP THE OH VALLEY INTO SRN OH/ERN KY BY DAY/S END.
STRONG/HIGHLY ANOMALOUS ESE FLOW WILL RAPIDLY DEVELOP OVER THE MID
ATLANTIC STATES. THE NOSE OF THE FASTEST LOW/MID LVL FLOW WILL
EVENTUALLY POINT INTO SC PA. MAIN/PRIMARY LOW STARTS TO FILL AND
SECONDARY LOW JUST STARTING TO DEVELOP OVER VA/NC BORDER AT THE
END OF THE PD. ALMOST ALL GUIDANCE POINTS TO THE FIRST FLAKES
STARTING AROUND SUNSET IN SOMERSET CO. WILL HOLD POPS NEAR ZERO
ELSEWHERE FOR THE DAYTIME.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
EXTENDED WATCH NORTH INTO MIFFLIN...JUNIATA...PERRY...DAUPHIN AND
LEBANON COUNTIES LATEST GEFS AND SREF RUNS. STILL SIGNIFICANT
UNCERTAINTY IN NORTHWARD EXTEND OF SNOW BANDS WITH UPCOMING
SYSTEM...BUT THERE IS ENOUGH POTENTIAL FOR WARNING CRITERIA SNOWS
IN THIS AREA TO WARRANT A NORTHWARD EXTENSION IN THE WATCH. THIS
PUTS CENTRE COUNTY AND THE STATE COLLEGE AREA ON THE SOUTHERN EDGE
OF AREA OUTSIDE OF THE WATCH...BUT IT WILL BE A CLOSE CALL
LOCALLY. GEFS U-WIND ANOMALIES -3 TO -4 OVER AREA AND STRONGER TO
SE. VERY IMPRESSIVE.
PREVIOUS DISCUSSION FOLLOWS...
POTENTIAL FOR MIDWEEK WINTER STORM CONTINUES TO INCREASE AS MODELS
REMAIN CONSISTENT ON AN UPPER LOW TRACK ACROSS VA/NC BORDER TUE
NIGHT INTO WED. QPF BETWEEN MODELS COMING MORE INTO LINE AS
GRADIENT CONTINUES TO SLOWLY SHARPEN...WITH HIGHER QPFS THAT HAVE
BEGUN TO NOSE INTO SOUTHERN TIER REMAINING THERE IN 12Z RUNS...SO
POTENTIAL FOR HEAVY SNOW REMAINS. WITH ONSET OF SNOW ABOUT 26 HRS
AWAY IN THE SW /23Z TUE/...ADJUSTED HEADLINES TO UPGRADE OLD WATCH
TO A WARNING AND ADDED A RIBBON OF WINTER STORM WATCH FOR NEXT
LINE NORTH AND THEN ALONG REMAINDER OF SOUTHERN TIER WHERE
POTENTIAL DOES EXIST FOR 6+ INCHES...BUT TOTALS STILL REMAIN QUITE
FUZZY IN THAT REGION MAKING IT A TRICKY FORECAST FOR SOUTHERN AND
CENTRAL MTNS. INCREASING CONFIDENCE IN HIGHER SNOW AMOUNTS FOR SW
COUNTIES.
A BLEND OF GUIDANCE REMAINS BEST CHOICE...WITH NAM SPLITTING THE
DIFFERENCE BETWEEN THE NORTHERLY CURVING GFS AND EASTWARD
PROGRESSING ECMWF. EXPECT LIGHT SNOW TO DEVELOP DURING THE LATE
AFTERNOON HOURS OVER THE LAUREL HIGHLANDS WITH LITTLE ACCUMS EARLY
ON GIVEN WARM AFTERNOON SURFACE TEMPS. HIGHS WILL RANGE FROM THE
UPPER 30S OVER THE LAURELS AND NORTHWEST MOUNTAINS TO THE MID 40S
OVER THE SOUTHEAST.
A RATHER VIGOROUS SYSTEM WILL TRACK FROM THE LOWER OHIO VALLEY TO
THE MID ATLANTIC COAST WHILE A HIGHLY CYCLONIC AND STRONG 120+ KT
300 MB JET SUPPORTS THE LIKELIHOOD OF AN EXTENDED...18-24 HR
PERIOD OF ENHANCED SNOWFALL NEAR AND SOUTH OF THE MASON DIXON
LINE. SOME LIGHT SNOWFALL MAY EXTEND NORTHWARD TO THE CENTRAL
MOUNTAINS...BUT DO NOT EXPECT ANY ACCUMS NORTH OF I-80 AT THIS
TIME.
BEING ON THE NORTHERN EDGE OF SIGNIFICANT SNOWFALL WILL MAKE FOR
A CONTINUED CHALLENGING CALL OVER THE NEXT 24 TO 36 HOURS. A FAIR
AMOUNT OF CHANGE IN THE TRACK AND STRENGTH OF THE STORM IS STILL
POSSIBLE...EVEN AT THIS SHORT RANGE.
FOLLOWING THE STORM ON THURSDAY...A CHILLY AND RATHER GUSTY
NORTHERLY FLOW ARRIVES WITH ISOLATED TO SCATTERED MTN SNOW
SHOWERS...BEFORE HEIGHTS RISE AND DAYTIME TEMPS MODERATE TO NEAR
NORMAL BY FRIDAY AND SATURDAY. A FAST MOVING AND RELATIVELY
FLAT/WEAK NRN STREAM SHORTWAVE WILL TRACK ACROSS THE GREAT LAKES
AND NRN PENN OVER THE WEEKEND /WITH TIMING DIFFS BETWEEN
MODELS/...POSSIBLY ACCOMPANIED BY A FEW SHOWERS OF RAIN AND WET
SNOW UP NORTH. SOUTHERN PORTIONS OF PENN SHOULD STAY MAINLY DRY
THROUGH THE WEEKEND.
WARMING TREND CONTINUES INTO EARLY NEXT WEEK...WITH SIGNIFICANT
MODEL DIVERGENCE. BUT GENERAL PATTERN BRINGS INCREASED RIDGING
OVER EASTERN U.S. AS NEXT LOW PROGGED TO LIFT INTO GLAKES BY
MIDWEEK.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
SOME MINOR CHANGES TO THE 03Z TAFS.
THE SC DECK STARTING TO WORK BACK TO THE SOUTH...SO DID
BACK OFF ON THE CLEARING AT BFD FOR A FEW HOURS. FOR
UNV...SHOULD REMAIN CLEAR. MVFR CIG AT IPT.
MID AND HIGH CLDS WILL BUILD NORTHWARD DURING THE AFT ON TUE...
AS A COMPLEX STORM MOVES EAST FROM THE PLAINS. AT THIS
POINT...EXPECT NO SNOW PRIOR TO 00Z WED.
THE STORM SYSTEM WILL CONTINUE TO MOVE EASTWARD TUESDAY
NIGHT INTO WED. EXPECT SNOW ACROSS THE AREA TUESDAY NIGHT
INTO WED EVENING. SOME OF THE SNOW WILL BE ON THE HEAVY
SIDE...ESPECIALLY ACROSS THE SOUTHERN TAF SITES.
IMPROVING CONDITIONS FOR THU INTO SAT...AS HIGH PRESSURE
BUILDS EASTWARD.
OUTLOOK...
TUE NIGHT INTO WED EVENING...IFR AND MVFR WITH AREAS OF SNOW.
THU...MVFR/IFR -SHSN EARLY...OTHERWISE VFR.
FRI-SAT...VFR CONDITIONS AS HIGH PRESSURE BUILDS EASTWARD.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM EST
WEDNESDAY FOR PAZ033>035.
WINTER STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY
AFTERNOON FOR PAZ024>028-036-056-057-059-063>066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...DANGELO
LONG TERM...ROSS/RXR
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS SPOKANE WA
944 PM PST Mon Mar 4 2013
.SYNOPSIS...
Clouds will be on the increase tonight as a low pressure system
moves toward the region. Light rain and snow will spread into the
Inland Northwest on Tuesday into Tuesday night. Wet snow accumulations
will be possible Tuesday and Tuesday night in north central and
northeast Washington. Cool and showery weather will persist into
Thursday, with the Wednesday Night and Thursday be the time window
when we`ll have the heaviest snow accumulations across the
northern Washington Zones. High pressure is expected to return
Friday, Saturday and Sunday, bringing dry weather and near normal
temperatures.
&&
.DISCUSSION...
Infrared satellite as of 830 pm indicated a large closed low
centered at 47N/136W with an occluded front just off the
Washington and Oregon coast inside 130W. Over the Inland Northwest
tonight the air mass is dry with dew points in the teens and lower
20s at most locations. This combined with an easterly pressure
gradient with the approaching system will keep winds elevated
at 5-15 mph through the Idaho Panhandle at Sandpoint and Coeur
D`Alene as well as the palouse. Winds will also be slightly elevated
at Spokane and through the Upper Columbia Basin. This combined
with increasing high clouds will reduce radiational cooling and keep
low temperatures from dropping to their potential.
Concerning the occluded front...models show some timing
differences as to when precipitation develops across Central
Washington tomorrow. The HRRR has precip just reaching Seattle at
9 am...while the GFS shows light precip as far east as Wenatchee
at this same time. With the GFS initializing too moist along the East
Slopes of the Cascades, it is likely that the atmosphere will take
some time to moisten up. With the NAM and ECMWF favoring a slower
precip onset...decided to lower POPs tomorrow morning for
Leavenworth, Wenatchee, and Omak. This may mean that afternoon
precipitation chances will need lowering over Eastern Washington.
However with ECMWF and HRRR indicating the potential for some
elevated showers developing ahead of the front with ECMWF showing
700-500mb Theta-e lapse rates near 0C/KM...will not make any
changes for Eastern Washington. A later onset of precipitation
over Central Washington may also mean temperatures getting a
little warmer than current forecast highs in these areas. However
will let mid shift look at this further. JW
&&
.AVIATION...
06Z TAFS: An occluded front off the Washington and Oregon Coast will
spread an increasing chance for -RASN in the valleys along the East
Slopes of the Cascades (including KEAT) Tuesday afternoon. The dry
low level air mass and the stretching and weakening nature of the
front as it moves east Tuesday afternoon and evening leads to lower
confidence of precipitation impacting the remaining TAF sites and
used VCSH to account for spotty light precipitation expected. CIGS
should remain VFR at all TAF sites...except KEAT where low level
upslope flow and expected -RASN may lower CIGS down to MVFR. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 27 42 34 44 31 43 / 0 20 40 70 50 30
Coeur d`Alene 24 46 33 44 31 43 / 0 20 40 70 60 30
Pullman 26 48 36 47 32 45 / 0 10 50 60 50 30
Lewiston 30 54 38 54 36 51 / 0 10 30 50 40 30
Colville 28 41 31 47 29 46 / 0 50 60 80 60 40
Sandpoint 24 39 32 41 31 40 / 0 40 40 70 70 50
Kellogg 23 45 32 42 31 39 / 0 20 60 70 70 40
Moses Lake 28 41 34 48 32 49 / 0 50 50 60 30 20
Wenatchee 30 38 32 43 32 48 / 0 60 60 60 30 20
Omak 30 35 30 41 29 44 / 0 70 60 80 60 50
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
859 PM PST Mon Mar 4 2013
.SYNOPSIS...
Clouds will be on the increase tonight as a low pressure system
moves toward the region. Light rain and snow will spread into the
Inland Northwest on Tuesday into Tuesday night. Wet snow accumulations
will be possible Tuesday and Tuesday night in north central and
northeast Washington. Cool and showery weather will persist into
Thursday, with the Wednesday Night and Thursday be the time window
when we`ll have the heaviest snow accumulations across the
northern Washington Zones. High pressure is expected to return
Friday, Saturday and Sunday, bringing dry weather and near normal
temperatures.
&&
.DISCUSSION...
Infrared satellite as of 830 pm indicated a large closed low
centered at 47N/136W with an occluded front just off the
Washington and Oregon coast inside 130W. Over the Inland Northwest
tonight the air mass is dry with dew points in the teens and lower
20s at most locations. This combined with an easterly pressure
gradient with the approaching system will keep winds elevated
at 5-15 mph through the Idaho Panhandle at Sandpoint and Coeur
D`Alene as well as the palouse. Winds will also be slightly elevated
at Spokane and through the Upper Columbia Basin. This combined
with increasing high clouds will reduce radiational cooling and keep
low temperatures from dropping to their potential.
Concerning the occluded front...models show some timing
differences as to when precipitation develops across Central
Washington tomorrow. The HRRR has precip just reaching Seattle at
9 am...while the GFS shows light precip as far east as Wenatchee
at this same time. With the GFS initializing too moist along the East
Slopes of the Cascades, it is likely that the atmosphere will take
some time to moisten up. With the NAM and ECMWF favoring a slower
precip onset...decided to lower POPs tomorrow morning for
Leavenworth, Wenatchee, and Omak. This may mean that afternoon
precipitation chances will need lowering over Eastern Washington.
However with ECMWF and HRRR indicating the potential for some
elevated showers developing ahead of the front with ECMWF showing
700-500mb Theta-e lapse rates near 0C/KM...will not make any
changes for Eastern Washington. A later onset of precipitation
over Central Washington may also mean temperatures getting a
little warmer than current forecast highs in these areas. However
will let mid shift look at this further. JW
&&
.AVIATION...
00Z TAFS: Expect increasing high level clouds overnight and a
strengthening easterly winds...especially for Pullman where winds
of 13-18 kts from the SE will be likely. A cold front currently
off the Pac Nw coast will move into, then through the Cascades
late tonight and Tues. Due to the dry air mass close to the sfc
(temp/dew pt temp spreads of 20-30F) we`re not fcstg any fog
overnight. Concerning the front Tues...only light rain or
rain/snow mix is expected for the KEAT and KMWH TAF sites.
Ceilings and vsbys should remain VFR with this pcpn as ceilings
lower to no lower than about 5000 ft msl. bz
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 27 42 34 44 31 43 / 0 20 40 70 50 30
Coeur d`Alene 24 46 33 44 31 43 / 0 20 40 70 60 30
Pullman 26 48 36 47 32 45 / 0 10 50 60 50 30
Lewiston 30 54 38 54 36 51 / 0 10 30 50 40 30
Colville 28 41 31 47 29 46 / 0 50 60 80 60 40
Sandpoint 24 39 32 41 31 40 / 0 40 40 70 70 50
Kellogg 23 45 32 42 31 39 / 0 20 60 70 70 40
Moses Lake 28 41 34 48 32 49 / 0 50 50 60 30 20
Wenatchee 30 38 32 43 32 48 / 0 60 60 60 30 20
Omak 30 35 30 41 29 44 / 0 70 60 80 60 50
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
353 AM MST TUE MAR 5 2013
.SHORT TERM...AN UPPER LEVEL RIDGE WILL BUILD INTO THE RGN TODAY
WITH A DRY AIRMASS IN PLACE. SFC PTRN HAS A SFC ANTICLYCONE OVER
THE NERN PLAINS WHICH KEEPS WINDS NNW OVER THE FAR NERN CORNER
WHILE CLOSER TO THE FOOTHILLS LOW LVL WINDS ARE SELY. MEANWHILE
WITH SOME SNOW COVER AND SELY WINDS IT WILL BE INTERESTING TO SEE
HOW HIGH TEMPS GET THIS AFTN AS THERE ARE SOME WIDE RANGES BETWEEN
THE GUIDANCE NUMBERS. LATEST RAP AND NAM KEEP HIGHS IN THE 30S
FROM CENTRAL WELD INTO MORGAN AND ERN PORTIONS ADAMS AND ARAPAHOE
COUNTIES WITH HIGHS IN THE LOWER TO MID 40S IN THE WRN AND SRN
SUBURBS OF DENVER. MEANWHILE THE GFS AND HRRR ARE WARMER WITH
HIGHS IN THE 40S ACROSS ALL OF NERN CO WITH LOWER 50S OVER THE
WRN AND SRN SUBURBS OF DENVER. WITH SELY LOW LVL FLOW AT LOWER
LEVELS AND SOME LINGERING SNOW COVER WOULD HAVE TO BELIEVE HIGHS
WILL NOT BE AS WRM AS HRRR AND GFS SHOW SO WILL HAVE READINGS
MOSTLY IN THE 40 TO 45 DEGREE RANGE.
.LONG TERM...THE REST OF THE WORK WEEK PROMISES TO BE DRY AND WARM
AS A STRONG UPPER LEVEL RIDGE BUILDS OVER THE STATE. THE RIDGE
AXIS IS EXPECTED TO MOVE EAST OF COLORADO BY WEDNESDAY AFTERNOON
WITH INCREASING SOUTHWESTERLY FLOW ALOFT SPREADING OVER THE STATE
THURSDAY AND FRIDAY. MID AND UPPER LEVEL MOISTURE WILL INCREASE
FROM THE WEST THROUGH THE DAY ON FRIDAY AS A POTENT UPPER LOW
DEVELOPS OVER CALIFORNIA. FOR THE PAST COUPLE DAYS THE ECMWF HAS
BEEN SHOWING THIS UPPER LOW EVENTUALLY MOVING TO THE FOUR CORNERS
REGION AND BRINGING THE POTENTIAL FOR SNOW TO THE STATE OVER THE
WEEKEND. OTHER MEDIUM AND LONG RANGE MODELS WERE SHOWING DIFFERENT
SOLUTIONS...BUT THE LATEST RUN OF THE LATEST RUN OF THE GFS IS NOW
BEGINNING TO COME IN LINE WITH THE ECMWF. YESTERDAY AFTERNOON/S
FORECAST PACKAGE ALREADY HAD SNOW LIKELY ACROSS OUR FORECAST AREA
FOR SATURDAY...AND NOW IS NOT THE TIME TO MAKE ANY CHANGES TO
THAT. WE WILL BE LOOKING AT SUCCESSIVE MODEL RUNS OVER THE NEXT
COUPLE DAYS TO ASSESS IF THE ECMWF MODEL CONTINUES TO BE THE MODEL
SOLUTION TO BASE THE FORECAST ON. IF THE GFS AND NAM MODELS FALL
IN LINE WITH THE ECMWF THEN A SIGNIFICANT SNOW EVENT COULD BE IN
STORE FOR THIS WEEKEND. STAY TUNED FOR OUR LATER FORECAST
PACKAGES. THE WEATHER FOR EARLY NEXT WEEK IS GOING TO DEPEND ON
HOW LONG THE SATURDAY UPPER LOW LINGERS OVER THE REGION. THE ECMWF
AND GFS HAVE VERY DIFFERENT IDEAS ABOUT THIS...SO WILL JUST STICK
WITH A DECREASING CHANCE OF SNOW ON MONDAY FOR NOW.
&&
.AVIATION...VFR THRU TONIGHT. LOOKS LIKE THERE WILL BE AN
SFC ANTICYCLONE CENTERED OVER THE NERN PLAINS WHICH WILL KEEP LOW
LVL WINDS SELY MUCH OF THE DAY WITH SPEEDS AROUND 10 KTS OR SO. BY
THIS EARLY EVENING WINDS MAY GRADUALLY BECOME MORE SLY AND THEN
STAY DRAINAGE OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1049 AM EST TUE MAR 05 2013
.Forecast Update...
Issued at 1048 AM EST Tue Mar 5 2013
Did an update to adjust pops based on current radar trends. There
have been a few lightning strikes across far south central Kentucky,
so have kept the mention of a slight chance for thunderstorms in the
forecast. Otherwise, no major changes made.
&&
.Short Term (Now - Wednesday)...
Issued at 335 AM EST Tue Mar 5 2013
...Accumulating Snow Likely Tonight through Wed Morning...
A weak sfc low over Arkansas this morning will combine with a potent
upper low diving southeast across the Plains/Midwest to result in a
potent low pressure system strengthening over the Ohio Valley and
becoming nearly vertically stacked as it reaches the
Virginias/Carolinas by Wed afternoon. This system will be our main
focus for the next 24-36 hrs bringing rains and a few rumbles of
thunder today and then accumulating snow tonight into Wed.
Early this morning, good isentropic lift ahead of the aforementioned
sfc low was causing good rains to travel along and south of a sfc
trough over central KY. Thus, will continue 70-90% POPs through the
pre-dawn hours. The latest RAP guidance indicates that as the sfc
low moves into western KY around sunrise, we will start to see
precip become more isld-sct in nature for the rest of the morning
before ramping up again by early afternoon as the sfc low deepens
and moves through central KY. Also by late morning through early to
mid afternoon, an axis of instability with pass through south
central KY possible causing isld-sct embedded t-storms. T-storms
should remain relatively weak/elevated however.
The biggest threat with this weather system will arrive tonight as
the sfc low rapidly deepens in response to the arrival of the strong
upper low diving south into the Ohio Valley. This will create a
strong surge of cold air at the sfc with a trowal/comma head like
structure developing aloft. This setup will be favorable for
accumulating snows over southern Indiana and much of central KY.
Looking at soundings, rains should change over to snow from NW to SE
tonight between about 7-11 pm. Soundings suggest a decent period
during the overnight hours for accumulating snows especially over
southern Indiana and central KY along and north of I-64. Deep
moisture and combined with good forcing throughout the column should
could result in some moderate to heavy bands of snow overnight.
Overall think that 2-4 inches could accumulate overnight tonight
through Wed morning over much of southern Indiana and north
central/east central KY including the Louisville/Lexington metro
areas. South and east of this area, lesser amounts (up to 2 inches
would be most likely based on the latest model guidance. With these
advisory level snow accums in mind and the fact that snow will
likely be ongoing still during the Wed morning rush, went ahead and
decided to issue a Winter Wx Advy for this package which will run
from 0Z-18Z Wed. Adjustments to this advisory may need to be made
based on coming model runs today. Portions of southeast Indiana
and extreme northern KY may even stand a chance at 4+ inches of snow
accums, but did not feel confident enough in issuing anything more
than an winter wx advy at this point due to a pretty decent model
spread in snow accums. Drivers should plan extra travel time for
the Wed morning commute and use caution while driving in snow.
In addition to the snow for tonight into Wed morning, westerly winds
will gust into the 30-35 mph range especially during the pre-dawn
hours possibly resulting in some blowing snow. Winds should subside
somewhat by the rush hour however.
Highs today should reach the lower 40s to mid 50s. Lows tonight
should reach the upper 20s to around 20 degrees.
By late Wed morning or early afternoon, moisture will begin to pull
out of our area leaving isld snow showers or even just some
rain/drizzle on the back side as we lose ice crystals aloft and sfc
temps warm into the mid 30s for highs on Wed.
.Long Term (Wednesday Night through Monday)...
Issued at 255 AM EST Tue Mar 5 2013
Wednesday Night through Friday Night...
Current suite of deterministic and ensemble guidance is in pretty
good agreement through this portion of the forecast period. The
guidance suggest that the closed upper low will be exiting off the
US Mid-Atlantic coast at the beginning of the forecast period.
Upstream ridging to our west will gradually build into the region on
Thursday and Friday resulting in dry conditions along with a
moderating trend in temperatures. Cloudiness will likely be a
little to clear out Wednesday night as model time-height cross
sections show low-level moisture hanging around. More sufficient
clearing will take place on Thursday with partly cloudy skies and we
should see mostly sunny skies across the region on Friday.
Temperatures are a bit of a concern depending on how much snowfall
occurs with the Tuesday night/Wednesday system. For now have
trended the forecast a little on the cooler side of the guidance
envelope with upper 20s for lows Thursday morning. There is a bit
of spread in the guidance for Thursday. Feel that sticking close to
a blend of the ensemble guidance and the AllBlend (all model
consensus) is probably a good start at this point. Highs will range
from the lower-mid 40s in the north/northeastern sections with
middle 40s in the central and southwest sections. Lows Thursday
night and Friday morning should cool into the mid-upper 20s once
again due to good radiational cooling effects. Milder conditions
look likely for Friday with highs generally in the 50-55 degree
range with lows Friday night cooling into the lower 30s.
Saturday through Monday...
As we enter into the weekend, mid-level ridge axis is forecast to be
nearly overhead across the Ohio Valley as two large cutoff lows will
be to our east and west. This ridge axis should hold into Sunday as
well providing the area with mostly dry conditions along with milder
temperatures. Highs on Saturday have trended a little cooler in
tonight`s datasets. Still thinking that we`ll see highs in the
55-60 degree range on Saturday with highs in the lower 60s on
Sunday. Next weather maker looks to push into the region around
Monday as a large cutoff low pressure system out to our west slowly
churns eastward. There is a bit of spread between the more
progressive GFS solution and the slower Euro runs, for now have gone
closer to the Euro solution as the general model consensus is
usually too progressive/fast in the long term. Nonetheless, a
period of unsettled weather looks likely early next week along with
a cooldown in temperatures. Highs on Monday are likely to top out
in the upper 50s to the lower 60s.
&&
.Aviation (12Z TAF Issuance)...
Issued at 625 AM EST Tue Mar 5 2013
Isentropic lift ahead of an approaching sfc low has brought rain and
thickening low clouds to the area early this morning. Expect rain
to become less in coverage by 13-16Z across the area. MVFR
conditions look to prevail through the morning hours.
The aforementioned sfc low will move through central KY this
afternoon causing steady rains to pick up again by early afternoon.
Some models even indicate enough instability for a rumble of thunder
over south central KY. Did not include in BWG TAF due to low
confidence, but a VCTS is not out of the question. For this TAF
issuance, also backed off of IFR cigs as models have been too
aggressive bringing the lower cigs into the TAF sites. Will go
predominantly MVFR with a tempo group for IFR in moderate rain this
afternoon.
By late afternoon or early evening the sfc low will pass to our east
causing sfc winds to veer to the west and become gusty as colder air
rushes in. The latest models indicate a trowal/comma head like
structure on the back side of this weather system will bring
additional moisture in the from of -RASN then -SN tonight.
Accumulating snow will be possible especially at SDF/LEX which could
both see 1-4 inches by Wed morning. Cigs should stay in the low MVFR
cat overnight tonight with westerly winds gusting into the 25-30 kt
range.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR INZ076>079-083-084-
089>092.
KY...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR KYZ024-025-028>043-
045>049-053>057-064>067-077-078-081-082.
$$
Update...........EER
Short Term.......AMS
Long Term........MJ
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
653 AM EST TUE MAR 05 2013
.Forecast Update...
Issued at 650 AM EST Tue Mar 5 2013
Did a quick update to adjust POPs and thunder chances for the day.
Upstream radar imagery indicates morning rain will stick around
south central KY through mid morning. Also, downgraded t-storm
chances to isld as 0Z and 6Z soundings look pretty pessimistic as
far as getting much embedded thunder this afternoon.
&&
.Short Term (Now - Wednesday)...
Issued at 335 AM EST Tue Mar 5 2013
...Accumulating Snow Likely Tonight through Wed Morning...
A weak sfc low over Arkansas this morning will combine with a potent
upper low diving southeast across the Plains/Midwest to result in a
potent low pressure system strengthening over the Ohio Valley and
becoming nearly vertically stacked as it reaches the
Virginias/Carolinas by Wed afternoon. This system will be our main
focus for the next 24-36 hrs bringing rains and a few rumbles of
thunder today and then accumulating snow tonight into Wed.
Early this morning, good isentropic lift ahead of the aforementioned
sfc low was causing good rains to travel along and south of a sfc
trough over central KY. Thus, will continue 70-90% POPs through the
pre-dawn hours. The latest RAP guidance indicates that as the sfc
low moves into western KY around sunrise, we will start to see
precip become more isld-sct in nature for the rest of the morning
before ramping up again by early afternoon as the sfc low deepens
and moves through central KY. Also by late morning through early to
mid afternoon, an axis of instability with pass through south
central KY possible causing isld-sct embedded t-storms. T-storms
should remain relatively weak/elevated however.
The biggest threat with this weather system will arrive tonight as
the sfc low rapidly deepens in response to the arrival of the strong
upper low diving south into the Ohio Valley. This will create a
strong surge of cold air at the sfc with a trowal/comma head like
structure developing aloft. This setup will be favorable for
accumulating snows over southern Indiana and much of central KY.
Looking at soundings, rains should change over to snow from NW to SE
tonight between about 7-11 pm. Soundings suggest a decent period
during the overnight hours for accumulating snows especially over
southern Indiana and central KY along and north of I-64. Deep
moisture and combined with good forcing throughout the column should
could result in some moderate to heavy bands of snow overnight.
Overall think that 2-4 inches could accumulate overnight tonight
through Wed morning over much of southern Indiana and north
central/east central KY including the Louisville/Lexington metro
areas. South and east of this area, lesser amounts (up to 2 inches
would be most likely based on the latest model guidance. With these
advisory level snow accums in mind and the fact that snow will
likely be ongoing still during the Wed morning rush, went ahead and
decided to issue a Winter Wx Advy for this package which will run
from 0Z-18Z Wed. Adjustments to this advisory may need to be made
based on coming model runs today. Portions of southeast Indiana
and extreme northern KY may even stand a chance at 4+ inches of snow
accums, but did not feel confident enough in issuing anything more
than an winter wx advy at this point due to a pretty decent model
spread in snow accums. Drivers should plan extra travel time for
the Wed morning commute and use caution while driving in snow.
In addition to the snow for tonight into Wed morning, westerly winds
will gust into the 30-35 mph range especially during the pre-dawn
hours possibly resulting in some blowing snow. Winds should subside
somewhat by the rush hour however.
Highs today should reach the lower 40s to mid 50s. Lows tonight
should reach the upper 20s to around 20 degrees.
By late Wed morning or early afternoon, moisture will begin to pull
out of our area leaving isld snow showers or even just some
rain/drizzle on the back side as we lose ice crystals aloft and sfc
temps warm into the mid 30s for highs on Wed.
.Long Term (Wednesday Night through Monday)...
Issued at 255 AM EST Tue Mar 5 2013
Wednesday Night through Friday Night...
Current suite of deterministic and ensemble guidance is in pretty
good agreement through this portion of the forecast period. The
guidance suggest that the closed upper low will be exiting off the
US Mid-Atlantic coast at the beginning of the forecast period.
Upstream ridging to our west will gradually build into the region on
Thursday and Friday resulting in dry conditions along with a
moderating trend in temperatures. Cloudiness will likely be a
little to clear out Wednesday night as model time-height cross
sections show low-level moisture hanging around. More sufficient
clearing will take place on Thursday with partly cloudy skies and we
should see mostly sunny skies across the region on Friday.
Temperatures are a bit of a concern depending on how much snowfall
occurs with the Tuesday night/Wednesday system. For now have
trended the forecast a little on the cooler side of the guidance
envelope with upper 20s for lows Thursday morning. There is a bit
of spread in the guidance for Thursday. Feel that sticking close to
a blend of the ensemble guidance and the AllBlend (all model
consensus) is probably a good start at this point. Highs will range
from the lower-mid 40s in the north/northeastern sections with
middle 40s in the central and southwest sections. Lows Thursday
night and Friday morning should cool into the mid-upper 20s once
again due to good radiational cooling effects. Milder conditions
look likely for Friday with highs generally in the 50-55 degree
range with lows Friday night cooling into the lower 30s.
Saturday through Monday...
As we enter into the weekend, mid-level ridge axis is forecast to be
nearly overhead across the Ohio Valley as two large cutoff lows will
be to our east and west. This ridge axis should hold into Sunday as
well providing the area with mostly dry conditions along with milder
temperatures. Highs on Saturday have trended a little cooler in
tonight`s datasets. Still thinking that we`ll see highs in the
55-60 degree range on Saturday with highs in the lower 60s on
Sunday. Next weather maker looks to push into the region around
Monday as a large cutoff low pressure system out to our west slowly
churns eastward. There is a bit of spread between the more
progressive GFS solution and the slower Euro runs, for now have gone
closer to the Euro solution as the general model consensus is
usually too progressive/fast in the long term. Nonetheless, a
period of unsettled weather looks likely early next week along with
a cooldown in temperatures. Highs on Monday are likely to top out
in the upper 50s to the lower 60s.
&&
.Aviation (12Z TAF Issuance)...
Issued at 625 AM EST Tue Mar 5 2013
Isentropic lift ahead of an approaching sfc low has brought rain and
thickening low clouds to the area early this morning. Expect rain
to become less in coverage by 13-16Z across the area. MVFR
conditions look to prevail through the morning hours.
The aforementioned sfc low will move through central KY this
afternoon causing steady rains to pick up again by early afternoon.
Some models even indicate enough instability for a rumble of thunder
over south central KY. Did not include in BWG TAF due to low
confidence, but a VCTS is not out of the question. For this TAF
issuance, also backed off of IFR cigs as models have been too
aggressive bringing the lower cigs into the TAF sites. Will go
predominantly MVFR with a tempo group for IFR in moderate rain this
afternoon.
By late afternoon or early evening the sfc low will pass to our east
causing sfc winds to veer to the west and become gusty as colder air
rushes in. The latest models indicate a trowal/comma head like
structure on the back side of this weather system will bring
additional moisture in the from of -RASN then -SN tonight.
Accumulating snow will be possible especially at SDF/LEX which could
both see 1-4 inches by Wed morning. Cigs should stay in the low MVFR
cat overnight tonight with westerly winds gusting into the 25-30 kt
range.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR INZ076>079-083-084-
089>092.
KY...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR KYZ024-025-028>043-
045>049-053>057-064>067-077-078-081-082.
$$
Update...........AMS
Short Term.......AMS
Long Term........MJ
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
626 AM EST TUE MAR 05 2013
...Updated Aviation Discussion...
.Short Term (Now - Wednesday)...
Issued at 335 AM EST Tue Mar 5 2013
...Accumulating Snow Likely Tonight through Wed Morning...
A weak sfc low over Arkansas this morning will combine with a potent
upper low diving southeast across the Plains/Midwest to result in a
potent low pressure system strengthening over the Ohio Valley and
becoming nearly vertically stacked as it reaches the
Virginias/Carolinas by Wed afternoon. This system will be our main
focus for the next 24-36 hrs bringing rains and a few rumbles of
thunder today and then accumulating snow tonight into Wed.
Early this morning, good isentropic lift ahead of the aforementioned
sfc low was causing good rains to travel along and south of a sfc
trough over central KY. Thus, will continue 70-90% POPs through the
pre-dawn hours. The latest RAP guidance indicates that as the sfc
low moves into western KY around sunrise, we will start to see
precip become more isld-sct in nature for the rest of the morning
before ramping up again by early afternoon as the sfc low deepens
and moves through central KY. Also by late morning through early to
mid afternoon, an axis of instability with pass through south
central KY possible causing isld-sct embedded t-storms. T-storms
should remain relatively weak/elevated however.
The biggest threat with this weather system will arrive tonight as
the sfc low rapidly deepens in response to the arrival of the strong
upper low diving south into the Ohio Valley. This will create a
strong surge of cold air at the sfc with a trowal/comma head like
structure developing aloft. This setup will be favorable for
accumulating snows over southern Indiana and much of central KY.
Looking at soundings, rains should change over to snow from NW to SE
tonight between about 7-11 pm. Soundings suggest a decent period
during the overnight hours for accumulating snows especially over
southern Indiana and central KY along and north of I-64. Deep
moisture and combined with good forcing throughout the column should
could result in some moderate to heavy bands of snow overnight.
Overall think that 2-4 inches could accumulate overnight tonight
through Wed morning over much of southern Indiana and north
central/east central KY including the Louisville/Lexington metro
areas. South and east of this area, lesser amounts (up to 2 inches
would be most likely based on the latest model guidance. With these
advisory level snow accums in mind and the fact that snow will
likely be ongoing still during the Wed morning rush, went ahead and
decided to issue a Winter Wx Advy for this package which will run
from 0Z-18Z Wed. Adjustments to this advisory may need to be made
based on coming model runs today. Portions of southeast Indiana
and extreme northern KY may even stand a chance at 4+ inches of snow
accums, but did not feel confident enough in issuing anything more
than an winter wx advy at this point due to a pretty decent model
spread in snow accums. Drivers should plan extra travel time for
the Wed morning commute and use caution while driving in snow.
In addition to the snow for tonight into Wed morning, westerly winds
will gust into the 30-35 mph range especially during the pre-dawn
hours possibly resulting in some blowing snow. Winds should subside
somewhat by the rush hour however.
Highs today should reach the lower 40s to mid 50s. Lows tonight
should reach the upper 20s to around 20 degrees.
By late Wed morning or early afternoon, moisture will begin to pull
out of our area leaving isld snow showers or even just some
rain/drizzle on the back side as we lose ice crystals aloft and sfc
temps warm into the mid 30s for highs on Wed.
.Long Term (Wednesday Night through Monday)...
Issued at 255 AM EST Tue Mar 5 2013
Wednesday Night through Friday Night...
Current suite of deterministic and ensemble guidance is in pretty
good agreement through this portion of the forecast period. The
guidance suggest that the closed upper low will be exiting off the
US Mid-Atlantic coast at the beginning of the forecast period.
Upstream ridging to our west will gradually build into the region on
Thursday and Friday resulting in dry conditions along with a
moderating trend in temperatures. Cloudiness will likely be a
little to clear out Wednesday night as model time-height cross
sections show low-level moisture hanging around. More sufficient
clearing will take place on Thursday with partly cloudy skies and we
should see mostly sunny skies across the region on Friday.
Temperatures are a bit of a concern depending on how much snowfall
occurs with the Tuesday night/Wednesday system. For now have
trended the forecast a little on the cooler side of the guidance
envelope with upper 20s for lows Thursday morning. There is a bit
of spread in the guidance for Thursday. Feel that sticking close to
a blend of the ensemble guidance and the AllBlend (all model
consensus) is probably a good start at this point. Highs will range
from the lower-mid 40s in the north/northeastern sections with
middle 40s in the central and southwest sections. Lows Thursday
night and Friday morning should cool into the mid-upper 20s once
again due to good radiational cooling effects. Milder conditions
look likely for Friday with highs generally in the 50-55 degree
range with lows Friday night cooling into the lower 30s.
Saturday through Monday...
As we enter into the weekend, mid-level ridge axis is forecast to be
nearly overhead across the Ohio Valley as two large cutoff lows will
be to our east and west. This ridge axis should hold into Sunday as
well providing the area with mostly dry conditions along with milder
temperatures. Highs on Saturday have trended a little cooler in
tonight`s datasets. Still thinking that we`ll see highs in the
55-60 degree range on Saturday with highs in the lower 60s on
Sunday. Next weather maker looks to push into the region around
Monday as a large cutoff low pressure system out to our west slowly
churns eastward. There is a bit of spread between the more
progressive GFS solution and the slower Euro runs, for now have gone
closer to the Euro solution as the general model consensus is
usually too progressive/fast in the long term. Nonetheless, a
period of unsettled weather looks likely early next week along with
a cooldown in temperatures. Highs on Monday are likely to top out
in the upper 50s to the lower 60s.
&&
.Aviation (12Z TAF Issuance)...
Issued at 625 AM EST Tue Mar 5 2013
Isentropic lift ahead of an approaching sfc low has brought rain and
thickening low clouds to the area early this morning. Expect rain
to become less in coverage by 13-16Z across the area. MVFR
conditions look to prevail through the morning hours.
The aforementioned sfc low will move through central KY this
afternoon causing steady rains to pick up again by early afternoon.
Some models even indicate enough instability for a rumble of thunder
over south central KY. Did not include in BWG TAF due to low
confidence, but a VCTS is not out of the question. For this TAF
issuance, also backed off of IFR cigs as models have been too
aggressive bringing the lower cigs into the TAF sites. Will go
predominantly MVFR with a tempo group for IFR in moderate rain this
afternoon.
By late afternoon or early evening the sfc low will pass to our east
causing sfc winds to veer to the west and become gusty as colder air
rushes in. The latest models indicate a trowal/comma head like
structure on the back side of this weather system will bring
additional moisture in the from of -RASN then -SN tonight.
Accumulating snow will be possible especially at SDF/LEX which could
both see 1-4 inches by Wed morning. Cigs should stay in the low MVFR
cat overnight tonight with westerly winds gusting into the 25-30 kt
range.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR INZ076>079-083-084-
089>092.
KY...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR KYZ024-025-028>043-
045>049-053>057-064>067-077-078-081-082.
$$
Short Term.......AMS
Long Term........MJ
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
731 AM EST TUE MAR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 516 AM EST TUE MAR 5 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW PRES
TROF OVER THE DAKOTAS DEEPENING INTO THE MID MS VALLEY AND CENTRAL
PLAINS WITH A DOWNSTREAM RIDGE OVER THE UPR GREAT LAKES. AT THE
SFC...A RIDGE EXTENDED FROM NRN MANITOBA AND NW ONTARIO INTO ERN
UPPER MI ALLOWING FOR ENE WINDS AND MAINLY CLEAR SKIES OVER THE ERN
HALF OF UPPER MI EARLY THIS MORNING. Q-VECT CONV AND ISENTROPIC
ASCENT AHEAD OF THE SFC LOW OVER ERN DAKOTAS INTO MID MS VALLEY HAS
RESULTED IN MID CLOUDS SPREADING INTO THE WRN HALF OF THE FCST AREA.
MODELS CONSISTENT IN DEVELOPING MID-LVL CLOSED LOW OVER THE LOWER
MIDWEST/MID MS VALLEY TODAY WITH DEEPENING TROF AND THEN TRACKING
THIS SYSTEM EAST THROUGH THE OHIO VALLEY REACHING THE MID-ATLANTIC
COAST BY WED MORNING. AS NE FLOW STRENGTHENS AND BECOMES MORE
CYCLONIC ON THE BACKSIDE OF THIS SYSTEM...CHANCES OF LAKE
ENHANCED SNOWFALL SHOULD INCREASE ESPECIALLY LATE TODAY INTO
WED MORNING FOR WEST AND NORTH CENTRAL PORTIONS OF THE FCST AREA
FAVORED BY N-NE FLOW.
MODEL SOUNDINGS SHOW INCREASING MOISTURE ESPECIALLY FM 925-800 MB
BEING PULLED BACK ACROSS LAKE SUPERIOR WITH STRENGTHENING CYCLONIC
NE FLOW LATER THIS AFTERNOON INTO TONIGHT...INCREASING THE POTENTIAL
FOR LAKE ENHANCED SNOWFALL OVER WEST AND NORTH CENTRAL AREAS. WITH
TEMPS AT 900 MB INVERSION HEIGHT (NEAR 3K FT) ONLY AROUND
-12C...INSTABILITY AND SLR VALUES WILL BE MARGINAL FOR SIGNFICANT
SNOWFALL. HOWEVER...UPSLOPE FLOW INTO THE HIGHER TERRAIN COULD BOOST
LIFT ENOUGH TO SUPPORT -SHSN THIS AFTERNOON WITH ACCUMULATIONS LESS
THAN A HALF INCH. FOR THIS REASON WILL MAINTAIN HIGH CHC TO LIKELY
POPS OVER HIGHER TERRAIN OF WRN MQT COUNTY LATER THIS AFTERNOON.
BETTER CHANCES OF LAKE ENHANCED SNOW WILL BE TONIGHT AS MOISTURE
PROFILE CONTINUES TO DEEPEN AND AREA OF MODERATE 850-500 MB Q-VECT
CONV SPREADS WEST TO EAST ACROSS THE FCST AREA. INCREASING LOW-LVL
CONVERGENCE IN N-NE FLOW WILL ALSO PROVIDE ADDED FOCUS FOR LAKE
ENHANCED SNOW...ESPECIALLY OVER THE HIGHER TERRAIN AREAS OF WRN MQT
COUNTY. HAVE BUMPED UP POPS TO CATEGORICAL OR GREATER THAN 80 PCT
OVER MUCH OF THE WEST AND NORTH CENTRAL FCST AREA TONIGHT. WITH SLR
VALUES OF 12-14/1 AND MODEL AVG QPF APPROACHING .15 INCH OVER
FAVORED UPSLOPE...WOULD NOT BE SURPRISED TO SEE ACCUMS EXCEED TWO
INCHES OVER SOME LOCATIONS OF WRN MQT COUNTY. MOST OTHER AREAS OF
THE WEST AND NORTH CENTRAL CWA WILL SEE SNOW ACCUMS CLOSER TO AN
INCH.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 516 AM EST TUE MAR 5 2013
WE START THE LONG TERM PERIOD 12Z WED LOOKING AT A 500MB TROUGH PUSHING
INTO WRN UPPER MI. HEIGHT FALLS AHEAD OF THE TROUGH WILL LEAD TO
SYNOPTIC SNOW OVER WRN UPPER MI BY 12Z WED...MOVING E OF THE CWA BY
06Z THU AS THE TROUGH CLOSES OFF INTO A LOW WHILE MOVING FROM NRN
LAKE SUPERIOR 00Z THU TO E OF LAKE SUPERIOR BY 12Z THU. IN ADDITION
TO THE SYNOPTIC SNOW...INVERSION TOP TEMPS AROUND 900MB WILL BE COLD
ENOUGH TO SUPPORT LAKE ENHANCEMENT/UPSLOPE SNOW WITH N-NW LOW LEVEL
WINDS. ESPECIALLY FAVORED WILL BE THE HIGHER TERRAIN OF N CENTRAL
AND WRN UPPER MI. EVEN SO...BEST LIFT WILL BE ABOVE THE DGZ...AND
TEMPS WILL STILL BE ON THE LOW END OF FAVORABLE...SO SNOW TO LIQUID
RATIOS WILL NOT BE AS HIGH AS THE COULD BE /BELOW 15 TO 1/ WHICH
WILL HELP LIMITED SNOWFALL AMOUNTS. LAKE ENHANCED SNOW WILL WEAKEN
QUICKLY AFTER SYNOPTIC SNOW MOVES E...BUT SOME LES IN COLDER TEMPS
BEHIND THE TROUGH WILL REMAIN POSSIBLE INTO THU WHEN WINDS BECOME
LIGHT AND BEGIN TO TURN SLY AFTER THE PASSAGE OF A SFC RIDGE. THINK
HIGHEST PRECIP AMOUNTS ON WED OVER THE HIGHER TERRAIN WILL BE AROUND
1 INCH.
UNCERTAINTY STARTS TO INCREASE ON FRI AS MODELS ARE HAVING
DIFFICULTY HANDLING SHORTWAVE ENERGY TOPPING THE UPPER RIDGE
OVERHEAD. MODELS DISAGREE WITH ONE ANOTHER AND FROM ONE RUN TO THE
NEXT...SO CONFIDENCE IS LOW AS TO THE POSITION OF ANY PRECIP FROM
THE SHORTWAVE ENERGY. IT DOES APPEAR THAT MOISTURE WILL BE LIMITED
ENOUGH TO KEEP PRECIP FROM BEING WIDESPREAD...BUT THAT IS AS MUCH
DETAIL AS CAN BE AFFORDED AT THIS POINT. USED A CONSENSUS OF
GUIDANCE FOR THIS PERIOD GIVEN THE LIMITED CONFIDENCE IN ANY ONE MODEL
EVEN MORE UNCERTAINTY AND LOWER CONFIDENCE FOR NEXT WEEKEND AND
EARLY NEXT WEEK AS MODELS STRUGGLE TO CONSISTENTLY HANDLE THE
PHASING OF THE NRN AND SRN STREAM SYSTEMS OVER NAMERICA. CONTINUED TO
USE A CONSENSUS OF GUIDANCE.
IN GENERAL...TEMPS SHOULD WARM INTO THE WEEKEND TO THE MID TO UPPER
30S BY SAT...WITH MUCH INCREASED UNCERTAINTY INTO MON.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 644 AM EST TUE MAR 5 2013
LOW PRESSURE DEVELOPING OVER THE MID MISSISSIPPI AND OHIO VALLEYS
TODAY WILL PULL DEEPER MOISTURE OVER UPPER MICHIGAN IN A NE
FLOW TODAY INTO TONIGHT. AS A RESULT...EXPECT SNOW SHOWERS TO BEGIN
LATE THIS MORNING/EARLY AFTERNOON AT ALL THREE TAF SITES WITH SNOW
SHOWERS INTENSIFYING SOME TONIGHT. LOW END MVFR CONDITIONS WILL BE
THE RULE THIS AFTERNOON LOWERING TO IFR TONIGHT AND PERHAPS LIFR AT
KSAW LATE TONIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 516 AM EST TUE MAR 5 2013
LOW PRESSURE CONSOLIDATING AND DEEPENING OVER THE TENNESSEE VALLEY
REGION WILL SUSTAIN NE WINDS TO 30 KTS OVER THE WRN THIRD OF LAKE
SUPERIOR TODAY WHERE LOW LEVEL CONV IS STRONGEST. NORTH WINDS TO 25
KTS CONTINUE THROUGH TONIGHT. DUE TO THE GUSTY WINDS AND COLDER
TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT TIMES THROUGH
TONIGHT. WINDS DIMINISH TO LESS THAN 20 KTS LATER WEDNESDAY INTO
FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
517 AM EST TUE MAR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 516 AM EST TUE MAR 5 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW PRES
TROF OVER THE DAKOTAS DEEPENING INTO THE MID MS VALLEY AND CENTRAL
PLAINS WITH A DOWNSTREAM RIDGE OVER THE UPR GREAT LAKES. AT THE
SFC...A RIDGE EXTENDED FROM NRN MANITOBA AND NW ONTARIO INTO ERN
UPPER MI ALLOWING FOR ENE WINDS AND MAINLY CLEAR SKIES OVER THE ERN
HALF OF UPPER MI EARLY THIS MORNING. Q-VECT CONV AND ISENTROPIC
ASCENT AHEAD OF THE SFC LOW OVER ERN DAKOTAS INTO MID MS VALLEY HAS
RESULTED IN MID CLOUDS SPREADING INTO THE WRN HALF OF THE FCST AREA.
MODELS CONSISTENT IN DEVELOPING MID-LVL CLOSED LOW OVER THE LOWER
MIDWEST/MID MS VALLEY TODAY WITH DEEPENING TROF AND THEN TRACKING
THIS SYSTEM EAST THROUGH THE OHIO VALLEY REACHING THE MID-ATLANTIC
COAST BY WED MORNING. AS NE FLOW STRENGTHENS AND BECOMES MORE
CYCLONIC ON THE BACKSIDE OF THIS SYSTEM...CHANCES OF LAKE
ENHANCED SNOWFALL SHOULD INCREASE ESPECIALLY LATE TODAY INTO
WED MORNING FOR WEST AND NORTH CENTRAL PORTIONS OF THE FCST AREA
FAVORED BY N-NE FLOW.
MODEL SOUNDINGS SHOW INCREASING MOISTURE ESPECIALLY FM 925-800 MB
BEING PULLED BACK ACROSS LAKE SUPERIOR WITH STRENGTHENING CYCLONIC
NE FLOW LATER THIS AFTERNOON INTO TONIGHT...INCREASING THE POTENTIAL
FOR LAKE ENHANCED SNOWFALL OVER WEST AND NORTH CENTRAL AREAS. WITH
TEMPS AT 900 MB INVERSION HEIGHT (NEAR 3K FT) ONLY AROUND
-12C...INSTABILITY AND SLR VALUES WILL BE MARGINAL FOR SIGNFICANT
SNOWFALL. HOWEVER...UPSLOPE FLOW INTO THE HIGHER TERRAIN COULD BOOST
LIFT ENOUGH TO SUPPORT -SHSN THIS AFTERNOON WITH ACCUMULATIONS LESS
THAN A HALF INCH. FOR THIS REASON WILL MAINTAIN HIGH CHC TO LIKELY
POPS OVER HIGHER TERRAIN OF WRN MQT COUNTY LATER THIS AFTERNOON.
BETTER CHANCES OF LAKE ENHANCED SNOW WILL BE TONIGHT AS MOISTURE
PROFILE CONTINUES TO DEEPEN AND AREA OF MODERATE 850-500 MB Q-VECT
CONV SPREADS WEST TO EAST ACROSS THE FCST AREA. INCREASING LOW-LVL
CONVERGENCE IN N-NE FLOW WILL ALSO PROVIDE ADDED FOCUS FOR LAKE
ENHANCED SNOW...ESPECIALLY OVER THE HIGHER TERRAIN AREAS OF WRN MQT
COUNTY. HAVE BUMPED UP POPS TO CATEGORICAL OR GREATER THAN 80 PCT
OVER MUCH OF THE WEST AND NORTH CENTRAL FCST AREA TONIGHT. WITH SLR
VALUES OF 12-14/1 AND MODEL AVG QPF APPROACHING .15 INCH OVER
FAVORED UPSLOPE...WOULD NOT BE SURPRISED TO SEE ACCUMS EXCEED TWO
INCHES OVER SOME LOCATIONS OF WRN MQT COUNTY. MOST OTHER AREAS OF
THE WEST AND NORTH CENTRAL CWA WILL SEE SNOW ACCUMS CLOSER TO AN
INCH.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 516 AM EST TUE MAR 5 2013
WE START THE LONG TERM PERIOD 12Z WED LOOKING AT A 500MB TROUGH PUSHING
INTO WRN UPPER MI. HEIGHT FALLS AHEAD OF THE TROUGH WILL LEAD TO
SYNOPTIC SNOW OVER WRN UPPER MI BY 12Z WED...MOVING E OF THE CWA BY
06Z THU AS THE TROUGH CLOSES OFF INTO A LOW WHILE MOVING FROM NRN
LAKE SUPERIOR 00Z THU TO E OF LAKE SUPERIOR BY 12Z THU. IN ADDITION
TO THE SYNOPTIC SNOW...INVERSION TOP TEMPS AROUND 900MB WILL BE COLD
ENOUGH TO SUPPORT LAKE ENHANCEMENT/UPSLOPE SNOW WITH N-NW LOW LEVEL
WINDS. ESPECIALLY FAVORED WILL BE THE HIGHER TERRAIN OF N CENTRAL
AND WRN UPPER MI. EVEN SO...BEST LIFT WILL BE ABOVE THE DGZ...AND
TEMPS WILL STILL BE ON THE LOW END OF FAVORABLE...SO SNOW TO LIQUID
RATIOS WILL NOT BE AS HIGH AS THE COULD BE /BELOW 15 TO 1/ WHICH
WILL HELP LIMITED SNOWFALL AMOUNTS. LAKE ENHANCED SNOW WILL WEAKEN
QUICKLY AFTER SYNOPTIC SNOW MOVES E...BUT SOME LES IN COLDER TEMPS
BEHIND THE TROUGH WILL REMAIN POSSIBLE INTO THU WHEN WINDS BECOME
LIGHT AND BEGIN TO TURN SLY AFTER THE PASSAGE OF A SFC RIDGE. THINK
HIGHEST PRECIP AMOUNTS ON WED OVER THE HIGHER TERRAIN WILL BE AROUND
1 INCH.
UNCERTAINTY STARTS TO INCREASE ON FRI AS MODELS ARE HAVING
DIFFICULTY HANDLING SHORTWAVE ENERGY TOPPING THE UPPER RIDGE
OVERHEAD. MODELS DISAGREE WITH ONE ANOTHER AND FROM ONE RUN TO THE
NEXT...SO CONFIDENCE IS LOW AS TO THE POSITION OF ANY PRECIP FROM
THE SHORTWAVE ENERGY. IT DOES APPEAR THAT MOISTURE WILL BE LIMITED
ENOUGH TO KEEP PRECIP FROM BEING WIDESPREAD...BUT THAT IS AS MUCH
DETAIL AS CAN BE AFFORDED AT THIS POINT. USED A CONSENSUS OF
GUIDANCE FOR THIS PERIOD GIVEN THE LIMITED CONFIDENCE IN ANY ONE MODEL
EVEN MORE UNCERTAINTY AND LOWER CONFIDENCE FOR NEXT WEEKEND AND
EARLY NEXT WEEK AS MODELS STRUGGLE TO CONSISTENTLY HANDLE THE
PHASING OF THE NRN AND SRN STREAM SYSTEMS OVER NAMERICA. CONTINUED TO
USE A CONSENSUS OF GUIDANCE.
IN GENERAL...TEMPS SHOULD WARM INTO THE WEEKEND TO THE MID TO UPPER
30S BY SAT...WITH MUCH INCREASED UNCERTAINTY INTO MON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1217 AM EST TUE MAR 5 2013
EXPECT SNOW SHOWERS TO BEGIN LATE TONIGHT AT ALL THREE TAF SITES.
LOW PRESSURE WILL MOVE FROM THE NORTHERN PLAINS INTO THE OHIO VALLEY
OVERNIGHT AND TUESDAY. THIS WILL BRING SOME HIGH-MID LEVEL CLOUDS TO
THE AREA OVERNIGHT...AND LIMITED SUPPORT FOR SNOW AT IWD TONIGHT.
OTHERWISE...THIS SYSTEM WILL ALLOW SURFACE WINDS TO REMAIN EAST TO
NORTHEASTERLY INTO TOMORROW. AS A RESULT...LAKE EFFECT SNOW SHOWERS
WILL DEVELOP LATE TONIGHT AND LAST THROUGH TUESDAY AT ALL THREE
SITES. OVERALL...CONDITIONS SHOULD BE VFR THROUGH THE EARLY EVENING
TONIGHT...THEN DETERIORATE TO LOW END MVFR TOWARDS MORNING. LOW END
MVFR WILL BE THE RULE THROUGH THE REMAINDER OF THE DAY
TUESDAY...ESPECIALLY TOWARDS THE EVENING HOURS. SOME OF THE MODEL
GUIDANCE SUGGESTS IFR CONDITIONS DEVELOPING AFTER 3Z...HOWEVER
CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN THE TAF AT THIS TIME.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 516 AM EST TUE MAR 5 2013
LOW PRESSURE CONSOLIDATING AND DEEPENING OVER THE TENNESSEE VALLEY
REGION WILL SUSTAIN NE WINDS TO 30 KTS OVER THE WRN THIRD OF LAKE
SUPERIOR TODAY WHERE LOW LEVEL CONV IS STRONGEST. NORTH WINDS TO 25
KTS CONTINUE THROUGH TONIGHT. DUE TO THE GUSTY WINDS AND COLDER
TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT TIMES THROUGH
TONIGHT. WINDS DIMINISH TO LESS THAN 20 KTS LATER WEDNESDAY INTO
FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...MCD
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1031 AM EST TUE MAR 5 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK EAST THROUGH KENTUCKY TODAY. AN UPPER
LEVEL LOW WILL DIVE SOUTHEAST FROM THE NORTHERN PLAINS AND
STRENGTHEN AS IT CUTS THROUGH THE SOUTHERN OHIO VALLEY TONIGHT.
THESE LOW PRESSURE SYSTEMS WILL MOVE TO THE EAST COAST BY
WEDNESDAY MORNING AS HIGH PRESSURE BUILDS OVER THE MIDWEST.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AN AREA OF SHOWERS IS SPREADING UP ACROSS CENTRAL OHIO ASSOCIATED
WITH THE INITIAL SHOT OF ISENTROPIC LIFT. NOT MUCH OF THIS HAS BEEN
REACHING THE GROUND SO FAR..BUT IT DOES APPEAR TO FILLING IN SO
WILL NUDGE UP POPS ACROSS NORTHEASTERN AREAS THROUGH EARLY
AFTERNOON. PCPN BEHIND THIS IS MORE SPOTTY ACROSS NORTHERN
KENTUCKY AND SOUTHEAST INDIANA...BUT THIS TOO SHOULD FILL IN
THROUGH THIS AFTERNOON AS GOOD LOW LEVEL CONVERGENCE DEVELOPS
AHEAD OF THE APPROACHING LOW. COULD STILL SEE SOME SNOW MIXED WITH
RAIN ACROSS THE NORTH THROUGH LATE MORNING...BUT WE SHOULD WARM UP
ENOUGH BY EARLY THIS AFTERNOON TO PUSH PTYPE OVER TO ALL RAIN.
LATEST MODELS ARE A BIT WARMER AND THIS MAY DELAY ONSET OF
CHANGEOVER BACK TO SNOW A FEW HOURS. WILL ADJUST THE WEATHER GRIDS
ACCORDINGLY AND PUSH BACK START TIME FOR THE WSW ACROSS MUCH OF
THE AREA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
RAPID CHANGEOVER TO SNOW THIS EVENING WILL BE COMBINED WITH
MODERATE PRECIPITATION RATES DUE TO THE AFOREMENTIONED FRONT.
UPPER LOW UNDERCUTTING THE SURFACE LOW WILL HAVE THE LIONS SHARE
OF SNOW OCCUR THIS EVENING AND TAPER OFF OVERNIGHT WITH LIGHTER
ACCUMULATIONS EXPECTED THROUGH DAYBREAK. HAVE ADDED CINCY METRO
AREA TO THE WARNING AS 3-4 INCHES OF SNOW REMAINS POSSIBLE IN THE
EVENING AND OVERNIGHT TONIGHT...ESPECIALLY IF EITHER OF THESE LOWS
EXHIBIT A QUICKER MOVEMENT.
LINGERING LIGHT SNOW MAY SEE SOME ADDITIONAL ACCUMULATIONS EARLY
WEDNESDAY MORNING BUT MOST OF THE SNOW SHOULD BE OVER BY NOON.
LOWERED THE TEMPERATURES A BIT FOR WEDNESDAY NIGHT AND THURSDAY
WITH THE EXPECTED SNOW COVER ALLOWING A GOOD DROP IN TEMPS AND
LIMITING DAYTIME RISES. HIGH PRESSURE WILL BUILD IN TO THE WEST ON
THURSDAY AND CLOUD COVER WILL EXHIBIT AN EROSION FROM WEST TO
EAST...PARTICULARLY IN THE LATE DAY AS 850 TEMPS WARM SIGNIFICANTLY.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
MID/UPPER LEVEL RIDGE TO BUILD INTO THE GREAT LAKES/OHIO VALLEY THRU
THE END OF THE WEEK INTO NEXT WEEKEND. THIS FEATURE WILL RESULT IN
DRY WEATHER CONDITIONS WITH A SIGNIFICANT WARMUP. HIGHS ON THURSDAY
WILL RANGE FROM THE UPPER 30S NORTH TO THE MID 40S SOUTH. FRIDAYS
HIGHS WILL CLOSER TO NORMAL...RANGING FROM THE LOWER/MIDDLE 40S
NORTH TO THE LOWER 50S SOUTH. SATURDAYS HIGHS LOOK TO BE 6 TO 10
DEGREES ABOVE NORMAL...RANGING FROM THE UPPER 40S NORTH TO THE UPPER
50S SOUTH.
S/W ENERGY PASSING THRU SRN CANADA WILL FLATTEN THE FAR NRN PORTION
OF THE RIDGE WITH A WEAK SFC FRONT DROPPING SOUTH INTO THE GREAT
LAKES SAT NIGHT/SUNDAY. THIS FRONT LOOKS TO LOSE ITS IDENTITY WITH
LACK OF UPPER SUPPORT AND LIMITED MOISTURE. THEREFORE...WILL LIMIT
POPS TO SLIGHT CHC OF RAIN SHOWERS ACRS THE NORTH SUNDAY. SUNDAYS
HIGHS WILL CONTINUE TO BE ABOUT 10 DEGREES ABOVE NORMAL...RANGING
FROM NEAR 50 NW TO NEAR 60 SE.
A BETTER CHANCE FOR RAIN LOOKS TO OCCUR MONDAY AFTN AS MSTR
INCREASES AS THE FLOW BACKS HAD OF A SYSTEM MOVING OUT OF THE
CENTRAL PLAINS. WILL SPREAD CHANCE POPS ACRS THE FA FROM THE WEST.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
INITIAL SHOT OF RAIN AHEAD OF THE LOW CENTER IN WRN KY LOOKS LIKE
IT WILL SLIP MAINLY S OF THE TAF SITES INITIALLY THIS MORNING.
THE 06Z NAM HAS PICKED UP NICELY ON THIS. STILL PUT IN A TEMPO
GROUP FOR CVG/LUK/ILN FOR A CHC OF MVFR VSBYS/CIGS AS THE FEATURE
SLIPS E.
SFC LOW WILL DEEPEN AS IT WORKS E TODAY. ADDITIONAL RAIN WILL
DEVELOP LATER THIS MORNING AND WILL SPREAD NWD. PCPN TYPE TODAY
SHOULD BE RAIN ACROSS ALL OF THE TAFS FOR MUCH OF THE DAY. CIGS
WILL LOWER TO MVFR AS THE PCPN SHIELD WORKS IN.
FOCUS THEN SHIFTS TO THE TIMING OF THE CHANGE OVER TO SNOW. 06Z
NAM AND THE 10Z RUC ARE INDICATING THAT THE CHANGE OVER MIGHT BE A
LITTLE SLOWER AND THE WARM AIR HANGS IN A LITTLE LONGER. BACKED
OFF ON THE CHANGE OVER BY AN HOUR OR SO...NOW 00-03Z IN THE W AND
03Z-06Z IN THE E. THE PCPN RATES WILL BE HEAVY AS THE CHANGE OVER
AS THE CHANGE OVER WILL BE DURING THE PERIOD OF MOST INTENSE
UPWARD LIFT. EXPECT A PERIOD OF MODERATE TO HEAVY SNOW AFTER THE
CHANGE OVER WITH LIFR CONDITIONS.
OUTLOOK...MVFR/IFR CONDITIONS WILL CONTINUE INTO WEDNESDAY. MVFR
CEILINGS MAY LINGER INTO THURSDAY MORNING.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 1 PM EST
WEDNESDAY FOR OHZ054>056-060>065-070>072-077>080.
WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR OHZ026-034-
035-042>046-051>053.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
WEDNESDAY FOR OHZ073-074-081-082-088.
KY...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 1 PM EST
WEDNESDAY FOR KYZ091>093.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
WEDNESDAY FOR KYZ089-090-094>100.
IN...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 1 PM EST
WEDNESDAY FOR INZ050-058-059-066-073-074.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
WEDNESDAY FOR INZ075-080.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...JGL
SHORT TERM...FRANKS
LONG TERM...AR
AVIATION...SITES
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
642 AM EST TUE MAR 5 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK EAST THROUGH KENTUCKY TODAY. AN UPPER
LEVEL LOW WILL DIVE SOUTHEAST FROM THE NORTHERN PLAINS AND
STRENGTHEN AS IT CUTS THROUGH THE SOUTHERN OHIO VALLEY TONIGHT.
THESE LOW PRESSURE SYSTEMS WILL MOVE TO THE EAST COAST BY
WEDNESDAY MORNING AS HIGH PRESSURE BUILDS OVER THE MIDWEST.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HAVE TRIED TO ADD MORE DETAIL TO THE FORECAST THIS MORNING AS RAIN
WILL DOMINATE TODAY AND BE MODERATE AT TIMES IN THE AFTERNOON. AS
THE UPPER LOW CUTS TO THE SOUTH...THERE WILL BE A VERY QUICK
CHANGE FROM MODERATE RAIN TO MODERATE SNOW AND SNOWFALL RATES
SHOULD EXCEED AN INCH PER HOUR. THE TIGHT POSITION OF THE SURFACE
LOW IN SOUTHWEST OHIO FOUND ANYWHERE FROM CINCINNATI TO
HILLSBORO TO CHILLICOTHE ADDS A LAYER OF COMPLEXITY THAT IS
DIFFICULT TO IMPART IN THE FORECAST. NORTH AND WEST OF METRO
DAYTON WILL SEE THE RAPID CHANGEOVER IN THE LATER
AFTERNOON...WHILE THE REST OF THE OHIO VALLEY WILL SEE THE
CHANGEOVER EARLY IN THE EVENING. THE WORST OF THE SNOWFALL WILL BE
OCCURRING THIS EVENING. MODERATE SNOW WILL TAPER OFF AFTER
MIDNIGHT BUT ADDITIONAL ACCUMULATIONS WILL BE POSSIBLE THROUGH
EARLY WEDNESDAY.
UPPER LEVEL RIDGE IS BREAKING DOWN AS SURFACE LOW MOVES NORTHEAST
THROUGH KENTUCKY TODAY. WARM AIR AT THE SURFACE WILL BE PULLED IN
WITH THIS LOW AS RAIN OVERSPREADS THE OHIO VALLEY AND CWA FROM THE
SOUTHWEST. THICKNESSES IN THE MIAMI VALLEY AND NORTHWEST OF DAYTON
WILL SUPPORT SOME SNOW MIXING IN THIS AFTERNOON WITH A CHANGEOVER
TO SNOW BY EVENING. PRECIPITATION WILL BE MODERATE AT TIMES AS THE
SURFACE LOW GETS ENERGY PULLED NORTHWEST AND A FRONT DEVELOPS.
RESULTING FRONT WILL EXTEND NORTHWEST FROM CINCY AREA TO
INDIANAPOLIS. SURFACE TEMPERATURES WILL REACH THE MID 30S
NORTH...UPPER 30S SOUTH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
RAPID CHANGEOVER TO SNOW THIS EVENING WILL BE COMBINED WITH
MODERATE PRECIPITATION RATES DUE TO THE AFOREMENTIONED FRONT.
UPPER LOW UNDERCUTTING THE SURFACE LOW WILL HAVE THE LIONS SHARE
OF SNOW OCCUR THIS EVENING AND TAPER OFF OVERNIGHT WITH LIGHTER
ACCUMULATIONS EXPECTED THROUGH DAYBREAK. HAVE ADDED CINCY METRO
AREA TO THE WARNING AS 3-4 INCHES OF SNOW REMAINS POSSIBLE IN THE
EVENING AND OVERNIGHT TONIGHT...ESPECIALLY IF EITHER OF THESE LOWS
EXHIBIT A QUICKER MOVEMENT.
LINGERING LIGHT SNOW MAY SEE SOME ADDITIONAL ACCUMULATIONS EARLY
WEDNESDAY MORNING BUT MOST OF THE SNOW SHOULD BE OVER BY NOON.
LOWERED THE TEMPERATURES A BIT FOR WEDNESDAY NIGHT AND THURSDAY
WITH THE EXPECTED SNOW COVER ALLOWING A GOOD DROP IN TEMPS AND
LIMITING DAYTIME RISES. HIGH PRESSURE WILL BUILD IN TO THE WEST ON
THURSDAY AND CLOUD COVER WILL EXHIBIT AN EROSION FROM WEST TO
EAST...PARTICULARLY IN THE LATE DAY AS 850 TEMPS WARM SIGNIFICANTLY.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
MID/UPPER LEVEL RIDGE TO BUILD INTO THE GREAT LAKES/OHIO VALLEY THRU
THE END OF THE WEEK INTO NEXT WEEKEND. THIS FEATURE WILL RESULT IN
DRY WEATHER CONDITIONS WITH A SIGNIFICANT WARMUP. HIGHS ON THURSDAY
WILL RANGE FROM THE UPPER 30S NORTH TO THE MID 40S SOUTH. FRIDAYS
HIGHS WILL CLOSER TO NORMAL...RANGING FROM THE LOWER/MIDDLE 40S
NORTH TO THE LOWER 50S SOUTH. SATURDAYS HIGHS LOOK TO BE 6 TO 10
DEGREES ABOVE NORMAL...RANGING FROM THE UPPER 40S NORTH TO THE UPPER
50S SOUTH.
S/W ENERGY PASSING THRU SRN CANADA WILL FLATTEN THE FAR NRN PORTION
OF THE RIDGE WITH A WEAK SFC FRONT DROPPING SOUTH INTO THE GREAT
LAKES SAT NIGHT/SUNDAY. THIS FRONT LOOKS TO LOSE ITS IDENTITY WITH
LACK OF UPPER SUPPORT AND LIMITED MOISTURE. THEREFORE...WILL LIMIT
POPS TO SLIGHT CHC OF RAIN SHOWERS ACRS THE NORTH SUNDAY. SUNDAYS
HIGHS WILL CONTINUE TO BE ABOUT 10 DEGREES ABOVE NORMAL...RANGING
FROM NEAR 50 NW TO NEAR 60 SE.
A BETTER CHANCE FOR RAIN LOOKS TO OCCUR MONDAY AFTN AS MSTR
INCREASES AS THE FLOW BACKS HAD OF A SYSTEM MOVING OUT OF THE
CENTRAL PLAINS. WILL SPREAD CHANCE POPS ACRS THE FA FROM THE WEST.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
INITIAL SHOT OF RAIN AHEAD OF THE LOW CENTER IN WRN KY LOOKS LIKE
IT WILL SLIP MAINLY S OF THE TAF SITES INITIALLY THIS MORNING.
THE 06Z NAM HAS PICKED UP NICELY ON THIS. STILL PUT IN A TEMPO
GROUP FOR CVG/LUK/ILN FOR A CHC OF MVFR VSBYS/CIGS AS THE FEATURE
SLIPS E.
SFC LOW WILL DEEPEN AS IT WORKS E TODAY. ADDITIONAL RAIN WILL
DEVELOP LATER THIS MORNING AND WILL SPREAD NWD. PCPN TYPE TODAY
SHOULD BE RAIN ACROSS ALL OF THE TAFS FOR MUCH OF THE DAY. CIGS
WILL LOWER TO MVFR AS THE PCPN SHIELD WORKS IN.
FOCUS THEN SHIFTS TO THE TIMING OF THE CHANGE OVER TO SNOW. 06Z
NAM AND THE 10Z RUC ARE INDICATING THAT THE CHANGE OVER MIGHT BE A
LITTLE SLOWER AND THE WARM AIR HANGS IN A LITTLE LONGER. BACKED
OFF ON THE CHANGE OVER BY AN HOUR OR SO...NOW 00-03Z IN THE W AND
03Z-06Z IN THE E. THE PCPN RATES WILL BE HEAVY AS THE CHANGE OVER
AS THE CHANGE OVER WILL BE DURING THE PERIOD OF MOST INTENSE
UPWARD LIFT. EXPECT A PERIOD OF MODERATE TO HEAVY SNOW AFTER THE
CHANGE OVER WITH LIFR CONDITIONS.
OUTLOOK...MVFR/IFR CONDITIONS WILL CONTINUE INTO WEDNESDAY. MVFR
CEILINGS MAY LINGER INTO THURSDAY MORNING.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING FROM 11 AM THIS MORNING TO 1 PM EST
WEDNESDAY FOR OHZ026-034-035-042>046-051>056-060>065-
070>072-077>080.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
WEDNESDAY FOR OHZ073-074-081-082-088.
KY...WINTER STORM WARNING FROM 11 AM THIS MORNING TO 1 PM EST
WEDNESDAY FOR KYZ091>093.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
WEDNESDAY FOR KYZ089-090-094>100.
IN...WINTER STORM WARNING FROM 11 AM THIS MORNING TO 1 PM EST
WEDNESDAY FOR INZ050-058-059-066-073-074.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
WEDNESDAY FOR INZ075-080.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...FRANKS
SHORT TERM...FRANKS
LONG TERM...AR
AVIATION...SITES
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1111 AM MST TUE MAR 5 2013
.UPDATE...
&&
.SHORT TERM...SHALLOW SNOW COVER IN MANY AREAS AND LIGHT WINDS
ARE RESTRAINING THE TEMPERATURE RISE TODAY ABOUT AS EXPECTED.
MINOR CHANGES TO HIGH TEMPERATURES...MAINLY COLDER IN THE VALLEYS
OF GRAND COUNTY.
&&
.AVIATION...VFR CONDITIONS THROUGH WEDNESDAY. LIGHT E-SE WINDS
THIS AFTERNOON WITH N-NE AT KBJC...KDEN COULD GO NE FOR A WHILE
BUT SHOULD BE LESS THAN 8 KNOTS IF IT DOES.
&&
.PREV DISCUSSION... /ISSUED 353 AM MST TUE MAR 5 2013/
SHORT TERM...AN UPPER LEVEL RIDGE WILL BUILD INTO THE RGN TODAY
WITH A DRY AIRMASS IN PLACE. SFC PTRN HAS A SFC ANTICLYCONE OVER
THE NERN PLAINS WHICH KEEPS WINDS NNW OVER THE FAR NERN CORNER
WHILE CLOSER TO THE FOOTHILLS LOW LVL WINDS ARE SELY. MEANWHILE
WITH SOME SNOW COVER AND SELY WINDS IT WILL BE INTERESTING TO SEE
HOW HIGH TEMPS GET THIS AFTN AS THERE ARE SOME WIDE RANGES BETWEEN
THE GUIDANCE NUMBERS. LATEST RAP AND NAM KEEP HIGHS IN THE 30S
FROM CENTRAL WELD INTO MORGAN AND ERN PORTIONS ADAMS AND ARAPAHOE
COUNTIES WITH HIGHS IN THE LOWER TO MID 40S IN THE WRN AND SRN
SUBURBS OF DENVER. MEANWHILE THE GFS AND HRRR ARE WARMER WITH
HIGHS IN THE 40S ACROSS ALL OF NERN CO WITH LOWER 50S OVER THE
WRN AND SRN SUBURBS OF DENVER. WITH SELY LOW LVL FLOW AT LOWER
LEVELS AND SOME LINGERING SNOW COVER WOULD HAVE TO BELIEVE HIGHS
WILL NOT BE AS WRM AS HRRR AND GFS SHOW SO WILL HAVE READINGS
MOSTLY IN THE 40 TO 45 DEGREE RANGE.
LONG TERM...THE REST OF THE WORK WEEK PROMISES TO BE DRY AND WARM
AS A STRONG UPPER LEVEL RIDGE BUILDS OVER THE STATE. THE RIDGE
AXIS IS EXPECTED TO MOVE EAST OF COLORADO BY WEDNESDAY AFTERNOON
WITH INCREASING SOUTHWESTERLY FLOW ALOFT SPREADING OVER THE STATE
THURSDAY AND FRIDAY. MID AND UPPER LEVEL MOISTURE WILL INCREASE
FROM THE WEST THROUGH THE DAY ON FRIDAY AS A POTENT UPPER LOW
DEVELOPS OVER CALIFORNIA. FOR THE PAST COUPLE DAYS THE ECMWF HAS
BEEN SHOWING THIS UPPER LOW EVENTUALLY MOVING TO THE FOUR CORNERS
REGION AND BRINGING THE POTENTIAL FOR SNOW TO THE STATE OVER THE
WEEKEND. OTHER MEDIUM AND LONG RANGE MODELS WERE SHOWING DIFFERENT
SOLUTIONS...BUT THE LATEST RUN OF THE LATEST RUN OF THE GFS IS NOW
BEGINNING TO COME IN LINE WITH THE ECMWF. YESTERDAY AFTERNOON/S
FORECAST PACKAGE ALREADY HAD SNOW LIKELY ACROSS OUR FORECAST AREA
FOR SATURDAY...AND NOW IS NOT THE TIME TO MAKE ANY CHANGES TO
THAT. WE WILL BE LOOKING AT SUCCESSIVE MODEL RUNS OVER THE NEXT
COUPLE DAYS TO ASSESS IF THE ECMWF MODEL CONTINUES TO BE THE MODEL
SOLUTION TO BASE THE FORECAST ON. IF THE GFS AND NAM MODELS FALL
IN LINE WITH THE ECMWF THEN A SIGNIFICANT SNOW EVENT COULD BE IN
STORE FOR THIS WEEKEND. STAY TUNED FOR OUR LATER FORECAST
PACKAGES. THE WEATHER FOR EARLY NEXT WEEK IS GOING TO DEPEND ON
HOW LONG THE SATURDAY UPPER LOW LINGERS OVER THE REGION. THE ECMWF
AND GFS HAVE VERY DIFFERENT IDEAS ABOUT THIS...SO WILL JUST STICK
WITH A DECREASING CHANCE OF SNOW ON MONDAY FOR NOW.
AVIATION...VFR THRU TONIGHT. LOOKS LIKE THERE WILL BE AN
SFC ANTICYCLONE CENTERED OVER THE NERN PLAINS WHICH WILL KEEP LOW
LVL WINDS SELY MUCH OF THE DAY WITH SPEEDS AROUND 10 KTS OR SO. BY
THIS EARLY EVENING WINDS MAY GRADUALLY BECOME MORE SLY AND THEN
STAY DRAINAGE OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION/UPDATE...GIMMESTAD
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
320 PM EST TUE MAR 5 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 405 AM EST TUE MAR 5 2013
LOW PRESSURE OVER NORTHERN ARKANSAS WILL TRACK NORTHEAST ACROSS THE
OHIO VALLEY LATER TODAY AS A STRONG UPPER LOW OVER THE NORTHERN
PLAINS MOVES TO KENTUCKY TONIGHT. THESE SYSTEMS WILL MERGE
RESULTING IN WINTER STORM CONDITIONS ACROSS PARTS OF OUR NORTH AND
EAST LATER TODAY AND TONIGHT AS COLDER AIR SPREADS INTO OUR REGION.
THIS SYSTEM WILL MOVE ON TO THE EAST WEDNESDAY AND HIGH PRESSURE
OVER THE CENTRAL U.S. WILL BUILD ACROSS OUR REGION THURSDAY AND
FRIDAY. TEMPERATURES WILL BECOME BY THE WEEKEND AS THE STRONG UPPER
LOW MOVES OFF THE EASTERN U.S. AND AN UPPER RIDGE OF HIGH PRESSURE
BUILDS OUR WAY.
THIS SYSTEM WILL CONTINUE ON TO THE EAST AND AND LOW PRESSURE
TRACKING FROM THE PLAINS INTO THE GREAT LAKES WILL BRING A CHANCE OF
RAIN EARLY NEXT WEEK.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1155 AM EST TUE MAR 5 2013
MUCH OF THE FORECAST AREA IN A RELATIVE LULL WITH LIGHT PRECIP AT
THE MOMENT THIS MORNING. LIGHT RAIN OCCASIONALLY MIXING WITH WET
SNOWFLAKES AND EVEN A FEW ICE PELLETS IMPACTING FAR NORTHERN
PORTIONS OF THE FORECAST AREA AT 16Z...WITH PRECIP EXPANDING INTO
THE REGION FROM THE SOUTHWEST WITH LOW PRESSURE APPROACHING. TEMPS
WERE GENERALLY IN THE 30S LATE THIS MORNING.
LOT TO TALK ABOUT FOR THE UPDATE WITH SOME CHANGES IN ORDER TO THE
HEADLINES AND SNOWFALL TOTALS BASED ON MOST RECENT MODEL DATA.
SOUNDINGS THIS MORNING SHOWING SLOW MOISTENING OF THE LOWER LEVELS
AND WILL SEE PRECIP COVERAGE EXPAND THIS AFTERNOON AS ISENTROPIC
LIFT AND FORCING ALOFT INCREASE WITH THE PASSAGE OF LOW PRESSURE
ALONG THE OHIO RIVER. MEANWHILE...INTENSE UPPER LOW CURRENTLY
DROPPING SOUTHEAST ACROSS IOWA WILL APPROACH AND ROTATE INTO THE
OHIO VALLEY BY THIS EVENING. MODEL SOUNDING AND 850MB TEMP
ANALYSIS SHOW COLDER AIR THROUGH THE BOUNDARY LAYER EXPANDING INTO
THE FORECAST AREA FROM THE NORTHWEST THROUGH THE AFTERNOON...WITH
PRECIP CHANGING OVER TO SNOW ACROSS THE ENTIRE FORECAST AREA BY 00Z.
ONCE THE CHANGEOVER TO SNOW TAKES PLACE...EXPECT A NUMBER OF
PARAMETERS TO COME INTO PLAY TO PROVIDE A PERIOD OF MODERATE TO
POTENTIALLY HEAVY SNOWFALL THIS EVENING FOCUSED ACROSS THE
NORTHEAST HALF OF THE FORECAST AREA...GENERALLY ALONG AND N/E OF THE
INTERSTATE 74 CORRIDOR. AS THE UPPER LOW ROTATES THROUGH THE OHIO
VALLEY THIS EVENING...AXIS OF MID LEVEL DEFORMATION COMBINED WITH
FRONTOGENETIC FORCING WILL COMBINE WITH STRONG ISENTROPIC LIFT...
HIGH DIV Q VALUES AND THE PASSAGE OF A DECENT DENDRITIC GROWTH
ZONE TO PROVIDE AMPLE FORCING FOR HEAVY SNOW. THESE FEATURES MAY
ALSO COMBINE TO ALLOW FOR HIGHER SNOW RATIOS UNDERNEATH THE DEEPER
FORCING WHICH WOULD SERVE TO ACCENTUATE SNOWFALL RATES. BY 06Z AS
THE SECONDARY COASTAL LOW BEGINS TO GET ITS ACT TOGETHER...MODEL
GUIDANCE SHOWING POTENTIAL FOR A STRONG LOW LEVEL JET TO PULL
ATLANTIC MOISTURE BACK WEST INTO THE REGION AND INTERACT WITH AN
IMPRESSIVE TROWAL TO MAINTAIN STRONG LIFT AND MODERATE TO HEAVY
SNOWFALL EVEN AS BETTER DEFORMATION AND MID LEVEL FORCING BEGINS
TO DIMINISH WITH THE UPPER LOW MOVING INTO THE CENTRAL
APPALACHIANS. THE TROWAL WILL THEN ROTATE SOUTHEAST THROUGH THE
FORECAST AREA BETWEEN 06-12Z ON THE BACK SIDE OF THE UPPER LOW.
THESE FEATURES ABOVE WITH THE MOISTURE PRESENT SUPPORT SNOWFALL
TOTALS BY WEDNESDAY MORNING NORTHEAST OF INTERSTATE 74 OF 4 TO 5
INCHES TO POSSIBLY AS MUCH AS 8 INCHES OVER NORTHEAST COUNTIES.
MAJORITY OF THE 12Z GUIDANCE SUPPORTS THIS THINKING...WITH THE NAM
AND RAP SUGGESTING POTENTIAL FOR EVEN HIGHER AMOUNTS TO THE
NORTHEAST OF INDY METRO. REGARDLESS CONSIDERING ABOVE
THOUGHTS...FEEL COMFORTABLE IN EXPANDING THE WARNING WEST A ROW OF
COUNTIES TO INCLUDE MARION COUNTY AND MUCH OF THE INDY METRO.
HEAVIEST SNOWFALL LIKELY TO COME THIS EVENING IN THE WARNING AREA
THROUGH ABOUT 06-08Z WITH GRADUALLY LIGHTENING RATES THEREAFTER AS
THE TROWAL ROTATES SOUTHEAST. FOR SIMPLICITY SAKE...HAVE ADJUSTED
ALL HEADLINES TO BEGIN AT 20Z.
WILL REVISIT DECISIONS FURTHER FOR MAIN FORECAST PACKAGE THIS
AFTERNOON AS MORE SHORT RANGE MODEL GUIDANCE BECOMES AVAILABLE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
ISSUED AT 405 AM EST TUE MAR 5 2013
ON WEDNESDAY...BROAD LOWER LEVEL CYCLONIC FLOW LOOKS TO PERSIST IN
THE WAKE OF THE DEPARTED LOW. A WEAK RIDGE OF HIGH PRESSURE
APPEARS SET UP OVER THE CENTRAL PLAINS AND MISSISSIPPI RIVER
VALLEY. THIS ALL TOO FAMILIAR PATTERN WAS MUCH OF WHAT WE
EXPERIENCED LAST WEEK...RESULTING IN CLOUDS...AND OCCASIONAL SNOW
SHOWERS OR FLURRIES. THUS WITH THE COLD CYCLONIC FLOW AND FORECAST
SOUNDINGS INDICATING GOOD MOISTURE WILL KEEP FLURRIES IN THE
FORECAST FOR NOW AND TREND HIGH TEMPS COOLER THAN MAVMOS.
NAM AND GFS INDICATE THE WEAK RIDGE WILL BUILD ACROSS THE AREA ON
WEDNESDAY NIGHT AND THURSDAY AND LOWER LEVEL FLOW BECOMES MORE
ANTI CYCLONIC THUS WILL TREND TOWARD PARTLY CLOUDY DURING THIS
TIME WITH TEMPERATURES BELOW GUIDANCE AS MINIMAL WARM AIR ADVECTION
LOOKS TO TAKE PLACE AND A SNOW PACK IS EXPECTED TO BE ON THE GROUND.
FURTHERMORE FORECAST SOUNDINGS STILL HINT AT LOWER LEVEL SATURATION
POSSIBLE WITH EASILY ATTAINABLE CONVECTIVE TEMPERATURES IN THE LOWER
30S.
HIGH PRESSURE WILL BUILD ACROSS OUR REGION THURSDAY AND FRIDAY. WITH
CLEARING SKIES AND SOME SNOW COVER WILL LOWER TEMPERATURES A LITTLE
FROM PREVIOUS FORECAST.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
ISSUED AT 241 AM EST TUE MAR 5 2013
LONG TERM PERIOD LOOKS TO BE A TALE OF TWO HALVES...WITH A FAIRLY
STRONG SURFACE AND UPPER RIDGE PROVIDING A QUIET END TO THE
WEEK...FOLLOWED A LARGE UPPER LEVEL SYSTEM WHICH WILL MOVE OUT OF
THE WEST AND BRING RAIN CHANCES FROM THE LATTER PART OF THE
WEEKEND INTO EARLY NEXT WEEK. GFS IS MUCH FASTER WITH THIS SYSTEM
WHICH LOOKS A LITTLE SUSPICIOUS GIVEN THE AFOREMENTIONED UPPER
RIDGE AND THE PRESENCE OF A CLOSED LOW. HAVE LEANED TOWARD EURO
AND DELAYED POPS FROM ALLBLEND INITIALIZATION.
OTHERWISE ALLBLEND INITIALIZED WELL. TEMPS SHOULD BE BACK TO NEAR
OR ABOVE CLIMATOLOGY FOR THE FIRST TIME IN A WHILE...AND
FORTUNATELY PRECIPITATION TYPE ISSUES LOOK TO BE NONEXISTENT FOR NOW.
&&
.AVIATION /DISCUSSION FOR THE 052100 KIND TAF UPDATE/...
ISSUED AT 320 PM EST TUE MAR 5 2013
STILL APPEARS RAIN WILL CHANGE OVER TO SNOW AT KIND OVER THE NEXT
COUPLE OF HOURS BASED ON UPSTREAM OBSERVATIONS...ALONG WITH A WIND
SHIFT TO 280-310 DEGREES AS A SURFACE TROUGH PASSES THROUGH.
WIDESPREAD IFR/LIFR SHOULD CONTINUE INTO THE EVENING HOURS. WILL
DROP THE WIND SPEEDS A LITTLE ON THE UPDATE WITH KIND NEAR THE
SURFACE TROUGH...OTHERWISE NO SIGNIFICANT CHANGES MADE AT THIS TIME.
PREVIOUS DISCUSSION FOLLOWS.
FLYING CONDITIONS ARE ALREADY BECOMING POOR EARLY THIS AFTERNOON AS
A WINTER STORM MOVES INTO THE OHIO VALLEY. PRECIP ACROSS THE AREA
ONLY IN THE FORM OF RAIN OR DRIZZLE AT THIS TIME. STILL EXPECTED
OVER THE NEXT FEW HOURS A TRANSITION TO -RASN...AND THEN EVENTUALLY
ALL SNOW BY THIS LATE AFTERNOON AND EVENING...WITH WIDESPREAD IFR
CONDITIONS OR WORSE EXPECTED. (MANY TERMINALS SUCH AS KIND HAVE
ALREADY DROPPED TO IFR AND THIS HAS BEEN DEPICTED IN THE LATEST SET
OF TAFS.
WINDS WILL STRENGTHEN TODAY AS THE PRESSURE GRADIENT TIGHTENS...AND
GUSTS APPROACHING 30KT OVERNIGHT TONIGHT ON THE BACK SIDE OF THE LOW
CAN BE EXPECTED IN MANY LOCATIONS.
AFTER THE SURFACE LOWS SLIDES TO THE EAST OF THE REGION BY WED
MORNING...PRECIPITATION WILL TAPER OFF SIGNIFICANTLY...HOWEVER AS IS
THE CASE WITH THESE SYSTEMS DURING THIS TIME OF YEAR...EXPECT FROM
LINGERING LIGHT SNOW AND/OR FLURRIES IN ADDITION TO THE STRATUS. SO
MFVR CONDITIONS WILL ROUND OUT THE END OF THE TAF PERIOD AND
POTENTIALLY CONTINUE BEYOND INTO WED NIGHT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR INZ021-028>031-037>042-047>049-056-057-065.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR INZ035-036-043>046-051>055-060>064-069>072.
&&
$$
SYNOPSIS...JH
NEAR TERM...RYAN
SHORT TERM...JH
LONG TERM....NIELD
AVIATION...SMF/JAS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1156 AM EST TUE MAR 5 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 405 AM EST TUE MAR 5 2013
LOW PRESSURE OVER NORTHERN ARKANSAS WILL TRACK NORTHEAST ACROSS THE
OHIO VALLEY LATER TODAY AS A STRONG UPPER LOW OVER THE NORTHERN
PLAINS MOVES TO KENTUCKY TONIGHT. THESE SYSTEMS WILL MERGE
RESULTING IN WINTER STORM CONDITIONS ACROSS PARTS OF OUR NORTH AND
EAST LATER TODAY AND TONIGHT AS COLDER AIR SPREADS INTO OUR REGION.
THIS SYSTEM WILL MOVE ON TO THE EAST WEDNESDAY AND HIGH PRESSURE
OVER THE CENTRAL U.S. WILL BUILD ACROSS OUR REGION THURSDAY AND
FRIDAY. TEMPERATURES WILL BECOME BY THE WEEKEND AS THE STRONG UPPER
LOW MOVES OFF THE EASTERN U.S. AND AN UPPER RIDGE OF HIGH PRESSURE
BUILDS OUR WAY.
THIS SYSTEM WILL CONTINUE ON TO THE EAST AND AND LOW PRESSURE
TRACKING FROM THE PLAINS INTO THE GREAT LAKES WILL BRING A CHANCE OF
RAIN EARLY NEXT WEEK.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1155 AM EST TUE MAR 5 2013
MUCH OF THE FORECAST AREA IN A RELATIVE LULL WITH LIGHT PRECIP AT
THE MOMENT THIS MORNING. LIGHT RAIN OCCASIONALLY MIXING WITH WET
SNOWFLAKES AND EVEN A FEW ICE PELLETS IMPACTING FAR NORTHERN
PORTIONS OF THE FORECAST AREA AT 16Z...WITH PRECIP EXPANDING INTO
THE REGION FROM THE SOUTHWEST WITH LOW PRESSURE APPROACHING. TEMPS
WERE GENERALLY IN THE 30S LATE THIS MORNING.
LOT TO TALK ABOUT FOR THE UPDATE WITH SOME CHANGES IN ORDER TO THE
HEADLINES AND SNOWFALL TOTALS BASED ON MOST RECENT MODEL DATA.
SOUNDINGS THIS MORNING SHOWING SLOW MOISTENING OF THE LOWER LEVELS
AND WILL SEE PRECIP COVERAGE EXPAND THIS AFTERNOON AS ISENTROPIC
LIFT AND FORCING ALOFT INCREASE WITH THE PASSAGE OF LOW PRESSURE
ALONG THE OHIO RIVER. MEANWHILE...INTENSE UPPER LOW CURRENTLY
DROPPING SOUTHEAST ACROSS IOWA WILL APPROACH AND ROTATE INTO THE
OHIO VALLEY BY THIS EVENING. MODEL SOUNDING AND 850MB TEMP
ANALYSIS SHOW COLDER AIR THROUGH THE BOUNDARY LAYER EXPANDING INTO
THE FORECAST AREA FROM THE NORTHWEST THROUGH THE AFTERNOON...WITH
PRECIP CHANGING OVER TO SNOW ACROSS THE ENTIRE FORECAST AREA BY 00Z.
ONCE THE CHANGEOVER TO SNOW TAKES PLACE...EXPECT A NUMBER OF
PARAMETERS TO COME INTO PLAY TO PROVIDE A PERIOD OF MODERATE TO
POTENTIALLY HEAVY SNOWFALL THIS EVENING FOCUSED ACROSS THE
NORTHEAST HALF OF THE FORECAST AREA...GENERALLY ALONG AND N/E OF THE
INTERSTATE 74 CORRIDOR. AS THE UPPER LOW ROTATES THROUGH THE OHIO
VALLEY THIS EVENING...AXIS OF MID LEVEL DEFORMATION COMBINED WITH
FRONTOGENETIC FORCING WILL COMBINE WITH STRONG ISENTROPIC LIFT...
HIGH DIV Q VALUES AND THE PASSAGE OF A DECENT DENDRITIC GROWTH
ZONE TO PROVIDE AMPLE FORCING FOR HEAVY SNOW. THESE FEATURES MAY
ALSO COMBINE TO ALLOW FOR HIGHER SNOW RATIOS UNDERNEATH THE DEEPER
FORCING WHICH WOULD SERVE TO ACCENTUATE SNOWFALL RATES. BY 06Z AS
THE SECONDARY COASTAL LOW BEGINS TO GET ITS ACT TOGETHER...MODEL
GUIDANCE SHOWING POTENTIAL FOR A STRONG LOW LEVEL JET TO PULL
ATLANTIC MOISTURE BACK WEST INTO THE REGION AND INTERACT WITH AN
IMPRESSIVE TROWAL TO MAINTAIN STRONG LIFT AND MODERATE TO HEAVY
SNOWFALL EVEN AS BETTER DEFORMATION AND MID LEVEL FORCING BEGINS
TO DIMINISH WITH THE UPPER LOW MOVING INTO THE CENTRAL
APPALACHIANS. THE TROWAL WILL THEN ROTATE SOUTHEAST THROUGH THE
FORECAST AREA BETWEEN 06-12Z ON THE BACK SIDE OF THE UPPER LOW.
THESE FEATURES ABOVE WITH THE MOISTURE PRESENT SUPPORT SNOWFALL
TOTALS BY WEDNESDAY MORNING NORTHEAST OF INTERSTATE 74 OF 4 TO 5
INCHES TO POSSIBLY AS MUCH AS 8 INCHES OVER NORTHEAST COUNTIES.
MAJORITY OF THE 12Z GUIDANCE SUPPORTS THIS THINKING...WITH THE NAM
AND RAP SUGGESTING POTENTIAL FOR EVEN HIGHER AMOUNTS TO THE
NORTHEAST OF INDY METRO. REGARDLESS CONSIDERING ABOVE
THOUGHTS...FEEL COMFORTABLE IN EXPANDING THE WARNING WEST A ROW OF
COUNTIES TO INCLUDE MARION COUNTY AND MUCH OF THE INDY METRO.
HEAVIEST SNOWFALL LIKELY TO COME THIS EVENING IN THE WARNING AREA
THROUGH ABOUT 06-08Z WITH GRADUALLY LIGHTENING RATES THEREAFTER AS
THE TROWAL ROTATES SOUTHEAST. FOR SIMPLICITY SAKE...HAVE ADJUSTED
ALL HEADLINES TO BEGIN AT 20Z.
WILL REVISIT DECISIONS FURTHER FOR MAIN FORECAST PACKAGE THIS
AFTERNOON AS MORE SHORT RANGE MODEL GUIDANCE BECOMES AVAILABLE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
ISSUED AT 405 AM EST TUE MAR 5 2013
ON WEDNESDAY...BROAD LOWER LEVEL CYCLONIC FLOW LOOKS TO PERSIST IN
THE WAKE OF THE DEPARTED LOW. A WEAK RIDGE OF HIGH PRESSURE
APPEARS SET UP OVER THE CENTRAL PLAINS AND MISSISSIPPI RIVER
VALLEY. THIS ALL TOO FAMILIAR PATTERN WAS MUCH OF WHAT WE
EXPERIENCED LAST WEEK...RESULTING IN CLOUDS...AND OCCASIONAL SNOW
SHOWERS OR FLURRIES. THUS WITH THE COLD CYCLONIC FLOW AND FORECAST
SOUNDINGS INDICATING GOOD MOISTURE WILL KEEP FLURRIES IN THE
FORECAST FOR NOW AND TREND HIGH TEMPS COOLER THAN MAVMOS.
NAM AND GFS INDICATE THE WEAK RIDGE WILL BUILD ACROSS THE AREA ON
WEDNESDAY NIGHT AND THURSDAY AND LOWER LEVEL FLOW BECOMES MORE
ANTI CYCLONIC THUS WILL TREND TOWARD PARTLY CLOUDY DURING THIS
TIME WITH TEMPERATURES BELOW GUIDANCE AS MINIMAL WARM AIR ADVECTION
LOOKS TO TAKE PLACE AND A SNOW PACK IS EXPECTED TO BE ON THE GROUND.
FURTHERMORE FORECAST SOUNDINGS STILL HINT AT LOWER LEVEL SATURATION
POSSIBLE WITH EASILY ATTAINABLE CONVECTIVE TEMPERATURES IN THE LOWER
30S.
HIGH PRESSURE WILL BUILD ACROSS OUR REGION THURSDAY AND FRIDAY. WITH
CLEARING SKIES AND SOME SNOW COVER WILL LOWER TEMPERATURES A LITTLE
FROM PREVIOUS FORECAST.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
ISSUED AT 241 AM EST TUE MAR 5 2013
LONG TERM PERIOD LOOKS TO BE A TALE OF TWO HALVES...WITH A FAIRLY
STRONG SURFACE AND UPPER RIDGE PROVIDING A QUIET END TO THE
WEEK...FOLLOWED A LARGE UPPER LEVEL SYSTEM WHICH WILL MOVE OUT OF
THE WEST AND BRING RAIN CHANCES FROM THE LATTER PART OF THE
WEEKEND INTO EARLY NEXT WEEK. GFS IS MUCH FASTER WITH THIS SYSTEM
WHICH LOOKS A LITTLE SUSPICIOUS GIVEN THE AFOREMENTIONED UPPER
RIDGE AND THE PRESENCE OF A CLOSED LOW. HAVE LEANED TOWARD EURO
AND DELAYED POPS FROM ALLBLEND INITIALIZATION.
OTHERWISE ALLBLEND INITIALIZED WELL. TEMPS SHOULD BE BACK TO NEAR
OR ABOVE CLIMATOLOGY FOR THE FIRST TIME IN A WHILE...AND
FORTUNATELY PRECIPITATION TYPE ISSUES LOOK TO BE NONEXISTENT FOR NOW.
&&
.AVIATION /DISCUSSION FOR THE 051800Z TAFS/...
ISSUED AT 1155 AM EST TUE MAR 5 2013
FLYING CONDITIONS ARE ALREADY BECOMING POOR EARLY THIS AFTERNOON AS
A WINTER STORM MOVES INTO THE OHIO VALLEY. PRECIP ACROSS THE AREA
ONLY IN THE FORM OF RAIN OR DRIZZLE AT THIS TIME. STILL EXPECTED
OVER THE NEXT FEW HOURS A TRANSITION TO -RASN...AND THEN EVENTUALLY
ALL SNOW BY THIS LATE AFTERNOON AND EVENING...WITH WIDESPREAD IFR
CONDITIONS OR WORSE EXPECTED. (MANY TERMINALS SUCH AS KIND HAVE
ALREADY DROPPED TO IFR AND THIS HAS BEEN DEPICTED IN THE LATEST SET
OF TAFS.
WINDS WILL STRENGTHEN TODAY AS THE PRESSURE GRADIENT TIGHTENS...AND
GUSTS APPROACHING 30KT OVERNIGHT TONIGHT ON THE BACK SIDE OF THE LOW
CAN BE EXPECTED IN MANY LOCATIONS.
AFTER THE SURFACE LOWS SLIDES TO THE EAST OF THE REGION BY WED
MORNING...PRECIPITATION WILL TAPER OFF SIGNIFICANTLY...HOWEVER AS IS
THE CASE WITH THESE SYSTEMS DURING THIS TIME OF YEAR...EXPECT FROM
LINGERING LIGHT SNOW AND/OR FLURRIES IN ADDITION TO THE STRATUS. SO
MFVR CONDITIONS WILL ROUND OUT THE END OF THE TAF PERIOD AND
POTENTIALLY CONTINUE BEYOND INTO WED NIGHT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR INZ021-028>031-037>042-047>049-056-057-065.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR INZ035-036-043>046-051>055-060>064-069>072.
&&
$$
SYNOPSIS...JH
NEAR TERM...RYAN
SHORT TERM...JH
LONG TERM....NIELD
AVIATION...SMF
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1155 AM EST TUE MAR 5 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 405 AM EST TUE MAR 5 2013
LOW PRESSURE OVER NORTHERN ARKANSAS WILL TRACK NORTHEAST ACROSS THE
OHIO VALLEY LATER TODAY AS A STRONG UPPER LOW OVER THE NORTHERN
PLAINS MOVES TO KENTUCKY TONIGHT. THESE SYSTEMS WILL MERGE
RESULTING IN WINTER STORM CONDITIONS ACROSS PARTS OF OUR NORTH AND
EAST LATER TODAY AND TONIGHT AS COLDER AIR SPREADS INTO OUR REGION.
THIS SYSTEM WILL MOVE ON TO THE EAST WEDNESDAY AND HIGH PRESSURE
OVER THE CENTRAL U.S. WILL BUILD ACROSS OUR REGION THURSDAY AND
FRIDAY. TEMPERATURES WILL BECOME BY THE WEEKEND AS THE STRONG UPPER
LOW MOVES OFF THE EASTERN U.S. AND AN UPPER RIDGE OF HIGH PRESSURE
BUILDS OUR WAY.
THIS SYSTEM WILL CONTINUE ON TO THE EAST AND AND LOW PRESSURE
TRACKING FROM THE PLAINS INTO THE GREAT LAKES WILL BRING A CHANCE OF
RAIN EARLY NEXT WEEK.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1155 AM EST TUE MAR 5 2013
MUCH OF THE FORECAST AREA IN A RELATIVE LULL WITH LIGHT PRECIP AT
THE MOMENT THIS MORNING. LIGHT RAIN OCCASIONALLY MIXING WITH WET
SNOWFLAKES AND EVEN A FEW ICE PELLETS IMPACTING FAR NORTHERN
PORTIONS OF THE FORECAST AREA AT 16Z...WITH PRECIP EXPANDING INTO
THE REGION FROM THE SOUTHWEST WITH LOW PRESSURE APPROACHING. TEMPS
WERE GENERALLY IN THE 30S LATE THIS MORNING.
LOT TO TALK ABOUT FOR THE UPDATE WITH SOME CHANGES IN ORDER TO THE
HEADLINES AND SNOWFALL TOTALS BASED ON MOST RECENT MODEL DATA.
SOUNDINGS THIS MORNING SHOWING SLOW MOISTENING OF THE LOWER LEVELS
AND WILL SEE PRECIP COVERAGE EXPAND THIS AFTERNOON AS ISENTROPIC
LIFT AND FORCING ALOFT INCREASE WITH THE PASSAGE OF LOW PRESSURE
ALONG THE OHIO RIVER. MEANWHILE...INTENSE UPPER LOW CURRENTLY
DROPPING SOUTHEAST ACROSS IOWA WILL APPROACH AND ROTATE INTO THE
OHIO VALLEY BY THIS EVENING. MODEL SOUNDING AND 850MB TEMP
ANALYSIS SHOW COLDER AIR THROUGH THE BOUNDARY LAYER EXPANDING INTO
THE FORECAST AREA FROM THE NORTHWEST THROUGH THE AFTERNOON...WITH
PRECIP CHANGING OVER TO SNOW ACROSS THE ENTIRE FORECAST AREA BY 00Z.
ONCE THE CHANGEOVER TO SNOW TAKES PLACE...EXPECT A NUMBER OF
PARAMETERS TO COME INTO PLAY TO PROVIDE A PERIOD OF MODERATE TO
POTENTIALLY HEAVY SNOWFALL THIS EVENING FOCUSED ACROSS THE
NORTHEAST HALF OF THE FORECAST AREA...GENERALLY ALONG AND N/E OF THE
INTERSTATE 74 CORRIDOR. AS THE UPPER LOW ROTATES THROUGH THE OHIO
VALLEY THIS EVENING...AXIS OF MID LEVEL DEFORMATION COMBINED WITH
FRONTOGENETIC FORCING WILL COMBINE WITH STRONG ISENTROPIC LIFT...
HIGH DIV Q VALUES AND THE PASSAGE OF A DECENT DENDRITIC GROWTH
ZONE TO PROVIDE AMPLE FORCING FOR HEAVY SNOW. THESE FEATURES MAY
ALSO COMBINE TO ALLOW FOR HIGHER SNOW RATIOS UNDERNEATH THE DEEPER
FORCING WHICH WOULD SERVE TO ACCENTUATE SNOWFALL RATES. BY 06Z AS
THE SECONDARY COASTAL LOW BEGINS TO GET ITS ACT TOGETHER...MODEL
GUIDANCE SHOWING POTENTIAL FOR A STRONG LOW LEVEL JET TO PULL
ATLANTIC MOISTURE BACK WEST INTO THE REGION AND INTERACT WITH AN
IMPRESSIVE TROWAL TO MAINTAIN STRONG LIFT AND MODERATE TO HEAVY
SNOWFALL EVEN AS BETTER DEFORMATION AND MID LEVEL FORCING BEGINS
TO DIMINISH WITH THE UPPER LOW MOVING INTO THE CENTRAL
APPALACHIANS. THE TROWAL WILL THEN ROTATE SOUTHEAST THROUGH THE
FORECAST AREA BETWEEN 06-12Z ON THE BACK SIDE OF THE UPPER LOW.
THESE FEATURES ABOVE WITH THE MOISTURE PRESENT SUPPORT SNOWFALL
TOTALS BY WEDNESDAY MORNING NORTHEAST OF INTERSTATE 74 OF 4 TO 5
INCHES TO POSSIBLY AS MUCH AS 8 INCHES OVER NORTHEAST COUNTIES.
MAJORITY OF THE 12Z GUIDANCE SUPPORTS THIS THINKING...WITH THE NAM
AND RAP SUGGESTING POTENTIAL FOR EVEN HIGHER AMOUNTS TO THE
NORTHEAST OF INDY METRO. REGARDLESS CONSIDERING ABOVE
THOUGHTS...FEEL COMFORTABLE IN EXPANDING THE WARNING WEST A ROW OF
COUNTIES TO INCLUDE MARION COUNTY AND MUCH OF THE INDY METRO.
HEAVIEST SNOWFALL LIKELY TO COME THIS EVENING IN THE WARNING AREA
THROUGH ABOUT 06-08Z WITH GRADUALLY LIGHTENING RATES THEREAFTER AS
THE TROWAL ROTATES SOUTHEAST. FOR SIMPLICITY SAKE...HAVE ADJUSTED
ALL HEADLINES TO BEGIN AT 20Z.
WILL REVISIT DECISIONS FURTHER FOR MAIN FORECAST PACKAGE THIS
AFTERNOON AS MORE SHORT RANGE MODEL GUIDANCE BECOMES AVAILABLE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
ISSUED AT 405 AM EST TUE MAR 5 2013
ON WEDNESDAY...BROAD LOWER LEVEL CYCLONIC FLOW LOOKS TO PERSIST IN
THE WAKE OF THE DEPARTED LOW. A WEAK RIDGE OF HIGH PRESSURE
APPEARS SET UP OVER THE CENTRAL PLAINS AND MISSISSIPPI RIVER
VALLEY. THIS ALL TOO FAMILIAR PATTERN WAS MUCH OF WHAT WE
EXPERIENCED LAST WEEK...RESULTING IN CLOUDS...AND OCCASIONAL SNOW
SHOWERS OR FLURRIES. THUS WITH THE COLD CYCLONIC FLOW AND FORECAST
SOUNDINGS INDICATING GOOD MOISTURE WILL KEEP FLURRIES IN THE
FORECAST FOR NOW AND TREND HIGH TEMPS COOLER THAN MAVMOS.
NAM AND GFS INDICATE THE WEAK RIDGE WILL BUILD ACROSS THE AREA ON
WEDNESDAY NIGHT AND THURSDAY AND LOWER LEVEL FLOW BECOMES MORE
ANTI CYCLONIC THUS WILL TREND TOWARD PARTLY CLOUDY DURING THIS
TIME WITH TEMPERATURES BELOW GUIDANCE AS MINIMAL WARM AIR ADVECTION
LOOKS TO TAKE PLACE AND A SNOW PACK IS EXPECTED TO BE ON THE GROUND.
FURTHERMORE FORECAST SOUNDINGS STILL HINT AT LOWER LEVEL SATURATION
POSSIBLE WITH EASILY ATTAINABLE CONVECTIVE TEMPERATURES IN THE LOWER
30S.
HIGH PRESSURE WILL BUILD ACROSS OUR REGION THURSDAY AND FRIDAY. WITH
CLEARING SKIES AND SOME SNOW COVER WILL LOWER TEMPERATURES A LITTLE
FROM PREVIOUS FORECAST.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
ISSUED AT 241 AM EST TUE MAR 5 2013
LONG TERM PERIOD LOOKS TO BE A TALE OF TWO HALVES...WITH A FAIRLY
STRONG SURFACE AND UPPER RIDGE PROVIDING A QUIET END TO THE
WEEK...FOLLOWED A LARGE UPPER LEVEL SYSTEM WHICH WILL MOVE OUT OF
THE WEST AND BRING RAIN CHANCES FROM THE LATTER PART OF THE
WEEKEND INTO EARLY NEXT WEEK. GFS IS MUCH FASTER WITH THIS SYSTEM
WHICH LOOKS A LITTLE SUSPICIOUS GIVEN THE AFOREMENTIONED UPPER
RIDGE AND THE PRESENCE OF A CLOSED LOW. HAVE LEANED TOWARD EURO
AND DELAYED POPS FROM ALLBLEND INITIALIZATION.
OTHERWISE ALLBLEND INITIALIZED WELL. TEMPS SHOULD BE BACK TO NEAR
OR ABOVE CLIMATOLOGY FOR THE FIRST TIME IN A WHILE...AND
FORTUNATELY PRECIPITATION TYPE ISSUES LOOK TO BE NONEXISTENT FOR NOW.
&&
.AVIATION /DISCUSSION FOR THE 051200Z TAFS/...
ISSUED AT 917 AM EST TUE MAR 5 2013
1430Z UPDATE...FEW COSMETIC CHANGES MADE TO THE TIMING FOR SEVERAL
OF THE TERMINALS. OTHERWISE NO OTHER CHANGES NEEDED AT THIS TIME.
PREVIOUS DISCUSSION FOLLOWS...
FLYING CONDITIONS BECOMING POOR THIS PERIOD AS A WINTER STORM MOVES
THROUGH THE REGION.
PRECIP ACROSS THE AREA SHOULD BEGIN AS ALL RAIN OR PERHAPS A VERY
BRIEF MIX AT LAF...BUT WITH MODELS TRENDING WARMER THINK THAT RAIN
IS THE PREDOMINANT TYPE THERE. PRECIP HAS BEEN SLOWER TO DEVELOP
THAN PREVIOUSLY EXPECTED AND HAVE DELAYED THIS SLIGHTLY.
BEGINNING EARLY THIS AFTERNOON AT LAF AND PUSHING SOUTH ACROSS THE
AREA...RAIN WILL GRADUALLY CHANGE TO SNOW. A COUPLE HOURS OF MIXED
RAIN AND SNOW...WITH AN OUTSIDE CHANCE AT SOME SLEET OR FREEZING
RAIN.
PRECIPITATION WILL BE ALL SNOW BY LATE AFTERNOON TO EARLY EVENING
ACROSS THE SITES...WITH WIDESPREAD IFR CONDITIONS OR WORSE EXPECTED.
WINDS WILL STRENGTHEN TODAY AS THE PRESSURE GRADIENT TIGHTENS...AND
MAY GUST APPROACHING 30KT OVERNIGHT TONIGHT ON THE BACK SIDE OF THE
LOW.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR INZ021-028>031-037>042-047>049-056-057-065.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR INZ035-036-043>046-051>055-060>064-069>072.
&&
$$
SYNOPSIS...JH
NEAR TERM...RYAN
SHORT TERM...JH
LONG TERM....NIELD
AVIATION...NIELD/SMF
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1212 PM EST TUE MAR 05 2013
...Updated Aviation Discussion...
.Forecast Update...
Issued at 1048 AM EST Tue Mar 5 2013
Did an update to adjust pops based on current radar trends. There
have been a few lightning strikes across far south central Kentucky,
so have kept the mention of a slight chance for thunderstorms in the
forecast. Otherwise, no major changes made.
&&
.Short Term (Now - Wednesday)...
Issued at 335 AM EST Tue Mar 5 2013
...Accumulating Snow Likely Tonight through Wed Morning...
A weak sfc low over Arkansas this morning will combine with a potent
upper low diving southeast across the Plains/Midwest to result in a
potent low pressure system strengthening over the Ohio Valley and
becoming nearly vertically stacked as it reaches the
Virginias/Carolinas by Wed afternoon. This system will be our main
focus for the next 24-36 hrs bringing rains and a few rumbles of
thunder today and then accumulating snow tonight into Wed.
Early this morning, good isentropic lift ahead of the aforementioned
sfc low was causing good rains to travel along and south of a sfc
trough over central KY. Thus, will continue 70-90% POPs through the
pre-dawn hours. The latest RAP guidance indicates that as the sfc
low moves into western KY around sunrise, we will start to see
precip become more isld-sct in nature for the rest of the morning
before ramping up again by early afternoon as the sfc low deepens
and moves through central KY. Also by late morning through early to
mid afternoon, an axis of instability with pass through south
central KY possible causing isld-sct embedded t-storms. T-storms
should remain relatively weak/elevated however.
The biggest threat with this weather system will arrive tonight as
the sfc low rapidly deepens in response to the arrival of the strong
upper low diving south into the Ohio Valley. This will create a
strong surge of cold air at the sfc with a trowal/comma head like
structure developing aloft. This setup will be favorable for
accumulating snows over southern Indiana and much of central KY.
Looking at soundings, rains should change over to snow from NW to SE
tonight between about 7-11 pm. Soundings suggest a decent period
during the overnight hours for accumulating snows especially over
southern Indiana and central KY along and north of I-64. Deep
moisture and combined with good forcing throughout the column should
could result in some moderate to heavy bands of snow overnight.
Overall think that 2-4 inches could accumulate overnight tonight
through Wed morning over much of southern Indiana and north
central/east central KY including the Louisville/Lexington metro
areas. South and east of this area, lesser amounts (up to 2 inches
would be most likely based on the latest model guidance. With these
advisory level snow accums in mind and the fact that snow will
likely be ongoing still during the Wed morning rush, went ahead and
decided to issue a Winter Wx Advy for this package which will run
from 0Z-18Z Wed. Adjustments to this advisory may need to be made
based on coming model runs today. Portions of southeast Indiana
and extreme northern KY may even stand a chance at 4+ inches of snow
accums, but did not feel confident enough in issuing anything more
than an winter wx advy at this point due to a pretty decent model
spread in snow accums. Drivers should plan extra travel time for
the Wed morning commute and use caution while driving in snow.
In addition to the snow for tonight into Wed morning, westerly winds
will gust into the 30-35 mph range especially during the pre-dawn
hours possibly resulting in some blowing snow. Winds should subside
somewhat by the rush hour however.
Highs today should reach the lower 40s to mid 50s. Lows tonight
should reach the upper 20s to around 20 degrees.
By late Wed morning or early afternoon, moisture will begin to pull
out of our area leaving isld snow showers or even just some
rain/drizzle on the back side as we lose ice crystals aloft and sfc
temps warm into the mid 30s for highs on Wed.
.Long Term (Wednesday Night through Monday)...
Issued at 255 AM EST Tue Mar 5 2013
Wednesday Night through Friday Night...
Current suite of deterministic and ensemble guidance is in pretty
good agreement through this portion of the forecast period. The
guidance suggest that the closed upper low will be exiting off the
US Mid-Atlantic coast at the beginning of the forecast period.
Upstream ridging to our west will gradually build into the region on
Thursday and Friday resulting in dry conditions along with a
moderating trend in temperatures. Cloudiness will likely be a
little to clear out Wednesday night as model time-height cross
sections show low-level moisture hanging around. More sufficient
clearing will take place on Thursday with partly cloudy skies and we
should see mostly sunny skies across the region on Friday.
Temperatures are a bit of a concern depending on how much snowfall
occurs with the Tuesday night/Wednesday system. For now have
trended the forecast a little on the cooler side of the guidance
envelope with upper 20s for lows Thursday morning. There is a bit
of spread in the guidance for Thursday. Feel that sticking close to
a blend of the ensemble guidance and the AllBlend (all model
consensus) is probably a good start at this point. Highs will range
from the lower-mid 40s in the north/northeastern sections with
middle 40s in the central and southwest sections. Lows Thursday
night and Friday morning should cool into the mid-upper 20s once
again due to good radiational cooling effects. Milder conditions
look likely for Friday with highs generally in the 50-55 degree
range with lows Friday night cooling into the lower 30s.
Saturday through Monday...
As we enter into the weekend, mid-level ridge axis is forecast to be
nearly overhead across the Ohio Valley as two large cutoff lows will
be to our east and west. This ridge axis should hold into Sunday as
well providing the area with mostly dry conditions along with milder
temperatures. Highs on Saturday have trended a little cooler in
tonight`s datasets. Still thinking that we`ll see highs in the
55-60 degree range on Saturday with highs in the lower 60s on
Sunday. Next weather maker looks to push into the region around
Monday as a large cutoff low pressure system out to our west slowly
churns eastward. There is a bit of spread between the more
progressive GFS solution and the slower Euro runs, for now have gone
closer to the Euro solution as the general model consensus is
usually too progressive/fast in the long term. Nonetheless, a
period of unsettled weather looks likely early next week along with
a cooldown in temperatures. Highs on Monday are likely to top out
in the upper 50s to the lower 60s.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1210 PM EST Tue Mar 5 2013
The surface low is over central Kentucky early this afternoon. As it
moves east through the afternoon, rain will continue to overspread
the region. Currently all TAF sites have cigs under 500 ft. As
heavier rains spread over the area this afternoon and tonight they
may improve a bit, but in general look to stay around or under 1
kft. Visibilities will be up and down through the afternoon as well
depending on how heavy precipitation is at the time.
As this system shifts east colder air will quickly move in. The
precipitation will change over to a mix of rain and snow around 00Z,
then to all snow by 03Z or so. This snow may become heavier at times
at SDF and LEX overnight as banding sets up, reducing visibilities
and cigs even more. In addition, winds will become very gusty late
this afternoon and shift to westerly, then northwesterly. Gusts of
25-30 knots will be common overnight.
By daybreak tomorrow conditions should be improving at SDF and BWG
as the heaviest snow showers move off to the east.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR INZ076>079-083-084-
089>092.
KY...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO
1 PM EST /NOON CST/ WEDNESDAY FOR KYZ024-025-028>043-
045>049-053>057-064>067-077-078-081-082.
$$
Update...........EER
Short Term.......AMS
Long Term........MJ
Aviation.........EER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
408 PM EST TUE MAR 5 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS SHORTWAVE
DROPPING SE INTO THE MID MISSISSIPPI VALLEY. WAVE IS BEING FORCED SE
BY MID LEVEL HIGH OVER QUEBEC. AS A RESULT...SYSTEM SNOW HAS PAST BY
TO THE W AND S OF UPPER MI TODAY. SOME VERY LIGHT LES IS OCCURRING
IN E TO NE FLOW ACROSS LAKE SUPERIOR INTO THE KEWEENAW AND NCNTRL
UPPER MI AS TEMPS AT THE BASE OF A LOW 3KFT INVERSION ARE JUST
SUFFICIENT FOR LES AT -11C. UNDER DOWNSLOPING E TO NE LOW-LEVEL
WINDS...THE ERN FCST AREA HAS ENJOYED A SUNNY DAY TODAY.
VIGOROUS SHORTWAVE/MID LEVEL LOW OVER THE MID MISSISSIPPI VALLEY
WILL MOVE TO VCNTY OF NC BY WED MORNING AND WILL HAVE LITTLE IMPACT
ON WEATHER HERE. WHAT WILL BE A FACTOR IS A NRN STREAM SHORTWAVE
THAT WILL BE DRIFTING INTO THE UPPER LAKES LATE TONIGHT/WED...
BRINGING A DECENT AREA OF DEEP LAYER FORCING PER QVECTORS. THE
APPROACHING SHORTWAVE WILL HELP SHARPEN LOW-LEVEL CYCLONIC N TO NE
FLOW ACROSS LAKE SUPERIOR TONIGHT/WED MORNING BEFORE WINDS SHIFT NW
WED AS THE WAVE REACHES THE AREA. WHILE LOW-LEVEL THERMAL PROFILE
CHANGES VERY LITTLE...OVERWATER INSTABILITY IS MORE THAN SUFFICIENT
FOR LAKE ENHANCEMENT...AND THE FACT THAT SOME VERY LIGHT LES IS
ALREADY OCCURRING SUGGESTS THERE SHOULD BE A DECENT UPTICK IN LES
TONIGHT/WED MORNING. WITH ALL MODEL GUIDANCE SHOWING A SSE TO NNW
ORIENTED SFC TROF DEVELOPING ACROSS ROUGHLY CNTRL LAKE SUPERIOR...IT
WOULD APPEAR THAT NW AND NCNTRL UPPER MI SHOULD BE FAVORED FOR MORE
PERSISTENT SNOW. SNOW TO WATER RATIOS SHOULD BE ON THE LOW SIDE
10-15 TO 1...EXCEPT IN THE VCNTY/ALONG THE AFORENTIONED SFC TROF
WHERE DEEPER VERTICAL MOTION...THOUGH NOT STRONG...SHOULD INTERSECT
THE DGZ AND POSSIBLY BOOST RATIOS TOWARD 20 TO 1. AT THIS POINT...IT
APPEARS ACCUMULATIONS UPWARDS OF AROUND 3 INCHES ARE POSSIBLE OVER
NW/NCNTRL HIGHER TERRAIN TONIGHT/WED MORNING. ACCUMULATIONS SHOULD
BE A LITTLE LESS FARTHER W TOWARD KIWD. IT REALLY WON`T BE UNTIL
LATER WED MORNING/AFTN WHEN SFC TROF PASSES THAT SNOW REACHES THE NE
FCST AREA. AWAY FROM LAKE ENHANCEMENT...EXPECT SOME -SN/-SHSN TIED
TO SHORT PERIOD OF STRONGER FORCING ASSOCIATED WITH SHORTWAVE. -SHSN
WILL DIMINISH W TO E WED AFTN AND MAY END OVER THE W.
TEMPS TONIGHT ARE FAIRLY STRAIGHTFORWARD WITH CLOUD COVER LIMITING
TEMP FALL. ONE EXCEPTION IS THE ERN FCST AREA AS IT`S UNCERTAIN WHEN
CLOUDS WILL INCREASE SUFFICIENTLY TO SLOW/STOP TEMP FALL THERE
TONIGHT. GIVEN THAT IT`S SUNNY IN THAT AREA NOW...AND SATELLITE
IMAGERY SHOWS NO TREND TO CLOUD UP SOON...TEMPS COULD PLUMMET
QUICKLY THIS EVENING. FCST WILL SHOW MINS IN THE MID TEENS...BUT
IT`S QUITE POSSIBLE TEMPS COULD FALL WELL DOWN INTO THE SINGLE
DIGITS DURING THE EVENING IF IT REMAINS MOSTLY CLEAR. MID 20S TO LWR
30S SHOULD BE THE RULE WED.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
LINGERING SURFACE TROUGH AND NORTHERN STREAM SHORTWAVE WILL BE
SLIDING EAST ACROSS EASTERN LAKE SUPERIOR ON WEDNESDAY EVENING WHILE
AN AREA OF HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES. WITH
900MB TEMPS STILL AROUND -12C AND ENOUGH LOW LEVEL MOISTURE BELOW
THE 3-4KFT INVERSION...SHOULD STILL SEE LOW CLOUDS ACROSS THE AREA
DURING THE EVENING IN THE NORTH-NORTHWEST WIND LOCATIONS. DURING THE
EVENING...WOULD EXPECT ISOLATED/SCATTERED SNOW SHOWERS IN THOSE SAME
WIND FAVORED LOCATIONS. WITH A LITTLE DEEPER MOISTURE OVER THE
EASTERN LOCATIONS...MAINLY FROM MUNISING EASTWARD...WOULD EXPECT
ISOLATED LIGHT SNOW SHOWERS TO CONTINUE THROUGH THE NIGHT. OVER THE
WEST...THE INFLUENCE OF THE HIGH WILL ALLOW THE FLOW TO BECOME
ANTI-CYCLONIC THROUGH THE NIGHT AND INCREASE THE DRY AIR OVER THE
WESTERN LAKE...SLOWLY DECREASING THE CLOUDS IN THAT AREA. THIS
DECREASE IN CLOUDS LEADS TO UNCERTAINTY IN THE LOWS OVER THE WESTERN
CWA. WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF
NORMAL...LOCATIONS THAT DO CLEAR OUT WILL LIKELY FALL INTO THE
SINGLE DIGITS AND WOULDN/T BE SURPRISED TO SEE A FEW BELOW ZERO
READINGS IN THE COLD SPOTS OF EASTERN GOGEBIC AND IRON COUNTY.
THE HIGH WILL CONTINUE TO MOVE OVER THE AREA ON THURSDAY...CAUSING
WINDS TO BECOME MORE VARIABLE. WITH THE STRENGTHENING SUBSIDENCE
INVERSION...THE QUESTION FOR THURSDAY WILL BE WHERE THE CLOUDS WILL
BE LOCATED AND IF/WHEN THEY WILL MIX OUT. WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING WILL LIKELY EAT AWAY AT THE CLOUDS.
UPPER RIDGE BUILDS OVER THE AREA ON THURSDAY NIGHT INTO
FRIDAY...WHICH WILL KEEP THE AREA DRY AND ONLY PRODUCE SOME
MID-HIGH CLOUDS STREAMING ACROSS THE AREA. BY FRIDAY NIGHT...AN
UPPER TROUGH WILL BE SITTING OVER THE SOUTHWEST CONUS AND A
NORTHERN STREAM TROUGH WILL BE MOVING THROUGH
MANITOBA/SASKATCHEWAN. THE QUESTION BECOMES WHETHER THESE TWO
TROUGHS WILL SEPARATE OR STAY TOGETHER...WHICH THEN INFLUENCES THE
FORECAST INTO THE FIRST PART OF NEXT WEEK. THE LATEST TRENDS IN THE
12Z MODEL RUNS IS TO KEEP THE WAVES PHASED ENOUGH THROUGH THE
WEEKEND DUE TO A STRONGER NORTHERN STREAM WAVE. THIS IN TURN LEADS
TO STRONGER FORCING WITH THE SURFACE TROUGH MOVING THROUGH SATURDAY
INTO SATURDAY EVENING. WITH THIS STRONGER WAVE AND INCREASED
SOUTHERLY FLOW AHEAD OF THE SYSTEM...MODELS HAVE TRENDED UP WITH
THE QPF...ESPECIALLY OVER THE WESTERN HALF OF THE CWA. HAVE TRENDED
POPS UP FOR THIS PERIOD AND WITH SOME OF THE QPF AMOUNTS SHOWN ON
THE 12Z RUNS...COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS
OVER WESTERN UPPER MICHIGAN. WON/T MENTION THIS IN THE HWO AT THIS
POINT WITH THE WAY THE MODELS HAVE BEEN VARYING...BUT WILL BE
SOMETHING TO WATCH. FINALLY...LOOKING AT MODEL SOUNDINGS...THEY TRY
TO NOSE TEMPS ABOVE 0C AROUND 850MB OVER THE SOUTH CENTRAL WHICH
COULD LEAD TO SOME MELTING ALONG THE ISOTHERMAL LAYER TO THE
SURFACE. THUS...ADDED A MIX OF RAIN/SNOW TO THAT AREA.
HIGH PRESSURE WILL LIKELY BUILD INTO THE UPPER GREAT LAKES FOR
SUNDAY AND THE FIRST PART OF MONDAY...BEFORE THE NEARLY
CLOSED SOUTHERN STREAM TROUGH DRIFTS OUT OF THE SOUTHWEST CONUS.
WHILE THIS SYSTEM WAS LOOKING LIKE IT WAS GOING TO MOVE TOWARDS THE
UPPER GREAT LAKES ON THE 12Z RUNS YESTERDAY...THE LATEST TRENDS
HAVE IT MOVING MORE THROUGH THE OHIO RIVER VALLEY. THEREFORE...HAVE
TRENDED POPS DOWN FOR THE MONDAY PERIOD AND IF THE TREND CONTINUES
THEY MAY NEED TO BE REMOVED COMPLETELY.
AS FOR TEMPERATURES DURING THE LONG TERM PERIOD...IT LOOKS TO BE
FAIRLY NORMAL WITH A FEW DAYS OF SLIGHTLY ABOVE NORMAL HIGHS
THROUGH THE WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1240 PM EST TUE MAR 5 2013
WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED
MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS
FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS THIS AFTN WITH -SHSN
DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR TONIGHT UNDER FAVORABLE
UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD VARY BTWN MVFR/IFR THIS
AFTN BEFORE FALLING TO PREVAILING IFR TONIGHT. AT KSAW...MVFR
CONDITIONS THIS AFTN WILL FALL TO IFR THIS EVENING AS -SHSN DEVELOP.
FAVORABLE CONVERGENT UPSLOPE FLOW OVERNIGHT WILL PROBABLY RESULT IN
CIGS FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATE WED
MORNING OR AFTN.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EST TUE MAR 5 2013
NE TO N WINDS OF 15-25KT WILL BE THE RULE ACROSS LAKE SUPERIOR
TONIGHT...THOUGH 20-30KT WINDS WILL LINGER OVER THE WRN PORTION OF
THE LAKE INTO THE EVENING HRS BEFORE PRES GRADIENT BEGINS TO RELAX.
WINDS WILL FALL OFF TO UNDER 20KT OVER WRN LAKE SUPERIOR WED. OVER
ERN LAKE SUPERIOR...TIGHTER PRES GRADIENT WILL ALLOW 15-25KT WINDS
TO PERSIST INTO EARLY THU MORNING. HIGH PRES RIDGE PASSING OVER THE
AREA WILL THEN LEAD TO WINDS UNDER 20KT ACROSS THE LAKE THU/FRI.
ALTHOUGH A LOW PRES TROF WILL PASS ACROSS LAKE SUPERIOR LATER
SAT/EARLY SUN...PRES GRADIENT REMAINS WEAK...KEEPING WINDS MOSTLY
UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1241 PM EST TUE MAR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 516 AM EST TUE MAR 5 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW PRES
TROF OVER THE DAKOTAS DEEPENING INTO THE MID MS VALLEY AND CENTRAL
PLAINS WITH A DOWNSTREAM RIDGE OVER THE UPR GREAT LAKES. AT THE
SFC...A RIDGE EXTENDED FROM NRN MANITOBA AND NW ONTARIO INTO ERN
UPPER MI ALLOWING FOR ENE WINDS AND MAINLY CLEAR SKIES OVER THE ERN
HALF OF UPPER MI EARLY THIS MORNING. Q-VECT CONV AND ISENTROPIC
ASCENT AHEAD OF THE SFC LOW OVER ERN DAKOTAS INTO MID MS VALLEY HAS
RESULTED IN MID CLOUDS SPREADING INTO THE WRN HALF OF THE FCST AREA.
MODELS CONSISTENT IN DEVELOPING MID-LVL CLOSED LOW OVER THE LOWER
MIDWEST/MID MS VALLEY TODAY WITH DEEPENING TROF AND THEN TRACKING
THIS SYSTEM EAST THROUGH THE OHIO VALLEY REACHING THE MID-ATLANTIC
COAST BY WED MORNING. AS NE FLOW STRENGTHENS AND BECOMES MORE
CYCLONIC ON THE BACKSIDE OF THIS SYSTEM...CHANCES OF LAKE
ENHANCED SNOWFALL SHOULD INCREASE ESPECIALLY LATE TODAY INTO
WED MORNING FOR WEST AND NORTH CENTRAL PORTIONS OF THE FCST AREA
FAVORED BY N-NE FLOW.
MODEL SOUNDINGS SHOW INCREASING MOISTURE ESPECIALLY FM 925-800 MB
BEING PULLED BACK ACROSS LAKE SUPERIOR WITH STRENGTHENING CYCLONIC
NE FLOW LATER THIS AFTERNOON INTO TONIGHT...INCREASING THE POTENTIAL
FOR LAKE ENHANCED SNOWFALL OVER WEST AND NORTH CENTRAL AREAS. WITH
TEMPS AT 900 MB INVERSION HEIGHT (NEAR 3K FT) ONLY AROUND
-12C...INSTABILITY AND SLR VALUES WILL BE MARGINAL FOR SIGNFICANT
SNOWFALL. HOWEVER...UPSLOPE FLOW INTO THE HIGHER TERRAIN COULD BOOST
LIFT ENOUGH TO SUPPORT -SHSN THIS AFTERNOON WITH ACCUMULATIONS LESS
THAN A HALF INCH. FOR THIS REASON WILL MAINTAIN HIGH CHC TO LIKELY
POPS OVER HIGHER TERRAIN OF WRN MQT COUNTY LATER THIS AFTERNOON.
BETTER CHANCES OF LAKE ENHANCED SNOW WILL BE TONIGHT AS MOISTURE
PROFILE CONTINUES TO DEEPEN AND AREA OF MODERATE 850-500 MB Q-VECT
CONV SPREADS WEST TO EAST ACROSS THE FCST AREA. INCREASING LOW-LVL
CONVERGENCE IN N-NE FLOW WILL ALSO PROVIDE ADDED FOCUS FOR LAKE
ENHANCED SNOW...ESPECIALLY OVER THE HIGHER TERRAIN AREAS OF WRN MQT
COUNTY. HAVE BUMPED UP POPS TO CATEGORICAL OR GREATER THAN 80 PCT
OVER MUCH OF THE WEST AND NORTH CENTRAL FCST AREA TONIGHT. WITH SLR
VALUES OF 12-14/1 AND MODEL AVG QPF APPROACHING .15 INCH OVER
FAVORED UPSLOPE...WOULD NOT BE SURPRISED TO SEE ACCUMS EXCEED TWO
INCHES OVER SOME LOCATIONS OF WRN MQT COUNTY. MOST OTHER AREAS OF
THE WEST AND NORTH CENTRAL CWA WILL SEE SNOW ACCUMS CLOSER TO AN
INCH.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 516 AM EST TUE MAR 5 2013
WE START THE LONG TERM PERIOD 12Z WED LOOKING AT A 500MB TROUGH PUSHING
INTO WRN UPPER MI. HEIGHT FALLS AHEAD OF THE TROUGH WILL LEAD TO
SYNOPTIC SNOW OVER WRN UPPER MI BY 12Z WED...MOVING E OF THE CWA BY
06Z THU AS THE TROUGH CLOSES OFF INTO A LOW WHILE MOVING FROM NRN
LAKE SUPERIOR 00Z THU TO E OF LAKE SUPERIOR BY 12Z THU. IN ADDITION
TO THE SYNOPTIC SNOW...INVERSION TOP TEMPS AROUND 900MB WILL BE COLD
ENOUGH TO SUPPORT LAKE ENHANCEMENT/UPSLOPE SNOW WITH N-NW LOW LEVEL
WINDS. ESPECIALLY FAVORED WILL BE THE HIGHER TERRAIN OF N CENTRAL
AND WRN UPPER MI. EVEN SO...BEST LIFT WILL BE ABOVE THE DGZ...AND
TEMPS WILL STILL BE ON THE LOW END OF FAVORABLE...SO SNOW TO LIQUID
RATIOS WILL NOT BE AS HIGH AS THE COULD BE /BELOW 15 TO 1/ WHICH
WILL HELP LIMITED SNOWFALL AMOUNTS. LAKE ENHANCED SNOW WILL WEAKEN
QUICKLY AFTER SYNOPTIC SNOW MOVES E...BUT SOME LES IN COLDER TEMPS
BEHIND THE TROUGH WILL REMAIN POSSIBLE INTO THU WHEN WINDS BECOME
LIGHT AND BEGIN TO TURN SLY AFTER THE PASSAGE OF A SFC RIDGE. THINK
HIGHEST PRECIP AMOUNTS ON WED OVER THE HIGHER TERRAIN WILL BE AROUND
1 INCH.
UNCERTAINTY STARTS TO INCREASE ON FRI AS MODELS ARE HAVING
DIFFICULTY HANDLING SHORTWAVE ENERGY TOPPING THE UPPER RIDGE
OVERHEAD. MODELS DISAGREE WITH ONE ANOTHER AND FROM ONE RUN TO THE
NEXT...SO CONFIDENCE IS LOW AS TO THE POSITION OF ANY PRECIP FROM
THE SHORTWAVE ENERGY. IT DOES APPEAR THAT MOISTURE WILL BE LIMITED
ENOUGH TO KEEP PRECIP FROM BEING WIDESPREAD...BUT THAT IS AS MUCH
DETAIL AS CAN BE AFFORDED AT THIS POINT. USED A CONSENSUS OF
GUIDANCE FOR THIS PERIOD GIVEN THE LIMITED CONFIDENCE IN ANY ONE MODEL
EVEN MORE UNCERTAINTY AND LOWER CONFIDENCE FOR NEXT WEEKEND AND
EARLY NEXT WEEK AS MODELS STRUGGLE TO CONSISTENTLY HANDLE THE
PHASING OF THE NRN AND SRN STREAM SYSTEMS OVER NAMERICA. CONTINUED TO
USE A CONSENSUS OF GUIDANCE.
IN GENERAL...TEMPS SHOULD WARM INTO THE WEEKEND TO THE MID TO UPPER
30S BY SAT...WITH MUCH INCREASED UNCERTAINTY INTO MON.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1240 PM EST TUE MAR 5 2013
WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED
MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS
FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS THIS AFTN WITH -SHSN
DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR TONIGHT UNDER FAVORABLE
UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD VARY BTWN MVFR/IFR THIS
AFTN BEFORE FALLING TO PREVAILING IFR TONIGHT. AT KSAW...MVFR
CONDITIONS THIS AFTN WILL FALL TO IFR THIS EVENING AS -SHSN DEVELOP.
FAVORABLE CONVERGENT UPSLOPE FLOW OVERNIGHT WILL PROBABLY RESULT IN
CIGS FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATE WED
MORNING OR AFTN.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 516 AM EST TUE MAR 5 2013
LOW PRESSURE CONSOLIDATING AND DEEPENING OVER THE TENNESSEE VALLEY
REGION WILL SUSTAIN NE WINDS TO 30 KTS OVER THE WRN THIRD OF LAKE
SUPERIOR TODAY WHERE LOW LEVEL CONV IS STRONGEST. NORTH WINDS TO 25
KTS CONTINUE THROUGH TONIGHT. DUE TO THE GUSTY WINDS AND COLDER
TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT TIMES THROUGH
TONIGHT. WINDS DIMINISH TO LESS THAN 20 KTS LATER WEDNESDAY INTO
FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...ROLFSON
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
423 PM EST TUE MAR 5 2013
.SYNOPSIS...
A WINTER STORM WILL AFFECT THE AREA TONIGHT AND EARLY WEDNESDAY.
HIGH PRESSURE WILL BUILD ACROSS THE REGION LATE THIS
WEEK...LASTING INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AN UPPER LOW IS DIVING SOUTHEASTWARD OUT OF THE NORTHERN PLAINS
AND INTO THE TENNESSEE VALLEY THIS EVENING. A SURFACE LOW
DEVELOPING OVER KENTUCKY...OUT AHEAD OF THE UPPER LOW WILL DEEPEN
AND PIVOT NORTHEASTWARD OVER THE OHIO VALLEY AS THE UPPER LOW
SLIDES BY TO THE SOUTH TONIGHT. PRECIPITATION IS ALREADY SPREADING
NORTHWARD ACROSS THE FORECAST AREA AHEAD OF THE INTENSIFYING
SURFACE LOW. PRECIPITATION WILL FALL AS RAIN ACROSS THE AREA INTO
THE EARLY EVENING...AS WARM AIR IS DRAWN NORTH AND WEST INTO THE
LOW LEVELS AROUND THE LOW.
THE FORECAST FOR LATER THIS EVENING BECOMES COMPLICATED...AS COLD
AIR BEGINS TO WORK ITS WAY BACK INTO THE LOW. THIS PROCESS WILL BE
TWOFOLD. LOW LEVEL COLD ADVECTION WILL ALLOW FOR COLDER AIR TO
WRAP INTO THE SURFACE LOW. AT THE SAME TIME...ABUNDANT VERTICAL
MOTION WILL PROVIDE FOR DYNAMIC COOLING FROM THE MIDDLE
LEVELS...PROPAGATING TO THE SURFACE. MODELS ARE IN AGREEMENT ON
THE STRONG VERTICAL MOTION ASSOCIATED WITH THIS SYSTEM THIS
EVENING ACROSS OUR AREA. HOWEVER...THERE ARE CRITICAL DIFFERENCES
IN HOW THE MODELS ARE HANDLING THE BATTLE BETWEEN DYNAMIC
COOLING...AND WARM AIR BEING PULLED IN AROUND THE LOW. BASED ON
HOW STRONG ASCENT IS AS HEAVIER PRECIPITATION MOVES IN THIS
EVENING...THIS FORECAST PACKAGE WENT WITH A MODERATELY FAST
CHANGEOVER TO SNOW TO BEGIN IN THE WESTERN ZONES AROUND 7
PM...SPREADING EAST THROUGH THE DAYTON/CINCY AREAS BY 9 PM...THEN
COLUMBUS BY 10 OR 11 PM. IF THE DYNAMIC COOLING PROCESS IS
STRONGER THAN THIS FORECAST IS HINTING AT...THEN THIS CHANGEOVER
WILL OCCUR SOONER...WITH THE RESULT BEING HIGHER SNOW TOTALS. OF
COURSE...IF ADDITIONAL WARMER AIR IS DRAW INTO THE SYSTEM...LIKE
THE RAP SUGGESTS THEN MORE RAIN WILL FALL INITIALLY. THE RAP
SOLUTION HAS BEEN ON THE WARM SIDE TODAY...THEREFORE AM LEANING
TOWARD THE COLDER SOLUTIONS.
ANY SNOW THAT OCCURS JUST AFTER THE CHANGEOVER WILL BE A
HEAVY...WET SNOW. THE BOTTOM LINE IS THAT THE MODELS LOOK AS IF
THEY ARE PICKING UP ON THE STRONGER LIFT BASED ON QPF AMOUNTS
RISING OVER RECENT RUNS. THIS MEANS A POTENTIAL FOR HIGHER STORM
TOTALS FOR OUR AREA. TOTAL SNOWFALL NUMBERS WERE THEREFORE TWEAKED
SLIGHTLY HIGHER...WITH THE MAXIMUM BEING AROUND 8 INCHES STORM
TOTAL ACROSS THE NORTHWESTERN ZONES. SOME OF THE SOUTHWESTERN
ZONES...WHERE A TRANSITION WILL OCCUR FIRST...MAY RECEIVE UP TO 4
INCHES OF SNOW. THE TRICKIEST SNOWFALL TOTAL FORECAST LIED WHERE
THE CENTER OF THE SURFACE LOW IS EXPECTED TO SPIN FOR A FEW HOURS
TONIGHT...ACROSS THE SCIOTO VALLEY. THERE...SNOWFALL AMOUNTS COULD
VARY QUITE A BIT...NOT ONLY DUE TO THE DELAYED CHANGEOVER DUE TO
SOME WARMER AIR...BUT THE LACK OF HEAVIER QPF UNDERNEATH THE LOW`S
CENTER LATE TONIGHT.
EXPANDED THE WINTER STORM WARNING TO INCLUDE SOME OUR OUR NORTHERN
KENTUCKY ZONES THAT ARE NOW EXPECTED TO REACH OUR 12 HOUR
CRITERIA OF 4 INCHES OF SNOW TONIGHT. DID DELAY THE START OF ALL
WARNINGS/ADVISORY EXCEPT ACROSS THE EXTREME NORTH...SINCE THAT
WARNING WAS ALREADY IN EFFECT AT THE TIME OF THE FORECAST PACKAGE
ISSUANCE.
SNOW WILL CONTINUE THROUGHOUT THE EARLY PRE-DAWN HOURS AS THE SURFACE
LOW SPINS ACROSS SOUTHEASTERN OHIO.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
THE UPPER LOW WILL QUICKLY SHIFT TOWARD THE MID ATLANTIC STATES
WEDNESDAY MORNING AS A SECONDARY SURFACE LOW DEVELOPS CLOSER TO
THE EASTERN SEABOARD. THIS ENERGY TRANSFER EASTWARD...AND AWAY
FROM OUR AREA WILL BRING A RAPID END TO FORCING SUPPORTING STEADY
SNOW IN OUR AREA. SNOW WILL TAPER OFF QUICKLY AROUND SUNRISE WITH
ONLY SOME LIGHTER SNOW SHOWERS EXPECTED DURING THE DAY.
NORTHERLY FLOW BEHIND THE DEPARTING STORM SYSTEM AND RIDGING
ACROSS THE NORTHERN PLAINS WILL KEEP A CHANCE FOR LIGHT SNOW OR
FLURRIES IN OUR AREA THROUGH WEDNESDAY NIGHT AND INTO THE DAY
THURSDAY. TEMPERATURES DURING THIS TIME PERIOD WILL REMAIN BELOW
NORMAL. LOW LEVEL MOISTURE...AND ASSOCIATED CLOUD COVER WILL
FINALLY BEGIN TO GIVE WAY TO DRIER CONDITIONS THURSDAY NIGHT...AS
THE RIDGE BUILDS ACROSS THE OHIO VALLEY. TEMPERATURES WILL LIKELY
BOTTOM OUT THURSDAY NIGHT IN THE UPPER TEENS TO LOW 20S UNDER
PARTLY CLOUDY SKIES.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AFTER A PLEASANT AND GENERALLY MILD WEEKEND...WITH GOOD MODEL
AGREEMENT...THERE IS CONSIDERABLE UNCERTAINTY ON A WEATHER SYSTEM
MOVING INTO THE REGION EARLY NEXT WEEK.
THE WEEKEND WILL BEGIN WITH A MID LEVEL TROUGH AXIS EXTENDING FROM
THE GULF OF MEXICO TO NORTHERN INDIANA. WARM ADVECTION WILL BE
UNDERWAY ALOFT...AND SHOULD BEGIN AT THE SURFACE AS WELL (AS WINDS
TAKE A SOUTHERLY COMPONENT). THIS PATTERN WILL GENERALLY CONTINUE
INTO SUNDAY...AS THE RIDGE AXIS MOVES EAST. WITH QUITE A BIT OF SUN
ON SATURDAY (PERHAPS JUST SOME LOW CLOUDS THAT ARE SLOW TO MOVE OUT
OF THE NORTHEASTERN CWA)...TEMPERATURES WILL RISE ABOVE NORMAL BY
ABOUT 5 DEGREES.
THE RIDGE WILL CONTINUE TO DOMINATE THE WEATHER ON SUNDAY...BUT AS
INFLUENCE FROM THE DEVELOPING WEATHER SYSTEM IN THE WESTERN STATES
BEGINS TO COMPLICATE THE FORECAST...SOME UNCERTAINTY WILL BEGIN TO
SET IN. MOISTURE WILL BEGIN TO ADVECT IN ALOFT...LEADING TO HIGH
CLOUDS THICKENING THROUGH THE DAY. DESPITE THIS...SURFACE WARM
ADVECTION WILL BE STRENGTHENING...LEADING TO EVEN WARMER TEMPS ON
SUNDAY.
BEYOND SUNDAY...A VERY HIGH AMOUNT OF UNCERTAINTY EXISTS IN THE
FORECAST. IT APPEARS CERTAIN THAT A WESTERN TROUGH WILL EJECT INTO
THE EASTERN STATES...AS SURFACE LOW PRESSURE DEVELOPS AND MOVES
THROUGH OR NEAR THE OHIO VALLEY. HOWEVER...THERE IS VERY LOW
CONFIDENCE IN THE TIMING OF THIS SYSTEM...AS WELL AS IN THE
PLACEMENT OF THE SURFACE LOW. DETERMINISTIC MODELS (12Z GFS VS 12Z
CMC VS 00Z ECMWF) ARE AS MUCH AS A DAY AND A HALF OFF IN
TIMING...WITH THE SURFACE LOW POSSIBLY GOING NORTH OR SOUTH OF THE
AREA. SO...AT THIS TIME...THE FORECAST WILL REMAIN VERY GENERAL.
ALTHOUGH IT IS FRUSTRATING TO GO NO HIGHER THAN 30 POPS WHEN RAIN
APPEARS A VIRTUAL CERTAINTY AT SOME POINT IN THE SUNDAY NIGHT
THROUGH TUESDAY TIME FRAME...THE TIMING DIFFERENCES ARE TOO GREAT TO
GO HIGHER.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
LIGHT PCPN IS CONTINUING ACROSS THE AREA EARLY THIS AFTERNOON.
STILL SEEING A LITTLE BIT OF SLEET AND SNOW MIXING IN ACROSS
CENTRAL OHIO...BUT THINK WE SHOULD BE JUST ABOUT OVER TO ALL FOR
THE REST OF THE AFTERNOON. A STRENGTHENING LOW PRESSURE SYSTEM WILL
PIVOT ACROSS THE AREA OVERNIGHT. AHEAD OF THIS...EXPECT MORE
WIDESPREAD/HEAVIER PCPN TO OVERSPREAD THE AREA FROM THE SOUTHWEST
THROUGH LATE AFTERNOON/EARLY EVENING. BEST FORCING WILL PIVOT UP
THROUGH THE AREA IN THE 00Z TO 03Z TIME FRAME. PCPN WILL START OFF
AS ALL RAIN...BUT SHOULD TRANSITION OVER TO SNOW FROM WEST TO EAST
ACROSS THE AREA THIS EVENING. THE EXACT TIME OF CHANGEOVER IS
STILL UNCERTAIN AS THERE WILL BE SOME WARM LOW LEVEL AIR BEING
PULLED IN FROM THE SOUTHEAST AHEAD OF THE LOW...WITH COLDER AIR
WRAPPING IN ON THE BACKSIDE OF IT. THIS WILL BE FURTHER
COMPLICATED BY THE POSSIBILITY OF SOME DYNAMIC COOLING GIVEN THE
INITIAL STRENGTH OF LIFT IN THE ATMOSPHERE. BEST GUESS IS A
CHANGEOVER AT KDAY AROUND 00Z...KCVG/KLUK 01Z...KILN 02Z AND
KCMH/KLCK 04Z. ONCE IT DOES CHANGE OVER...EXPECT A WET...HEAVY
SNOW FOR SEVERAL HOURS WITH IFR/LIFR VSBYS AND CIGS. SNOW WILL
THEN LINGER THROUGH MUCH OF THE NIGHT AS THE SURFACE LOW WOBBLES
ACROSS SOUTHERN OHIO INTO WEDNESDAY MORNING.
OUTLOOK...MVFR CEILINGS MAY LINGER INTO THURSDAY MORNING.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR OHZ054>056-
060>065-070>072-077>080.
WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR OHZ026-034-
035-042>046-051>053.
WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR OHZ073-
074-081-082-088.
KY...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR KYZ089>093.
WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR
KYZ094>100.
IN...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR INZ050-058-
059-066-073>075-080.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...HATZOS
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1256 PM EST TUE MAR 5 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL PASS OVER THE AREA TONIGHT AND EARLY
WEDNESDAY BRINGING RAIN AND SNOW SHOWERS TO THE WESTERN CAROLINAS.
DRIER HIGH PRESSURE WILL RETURN IN ITS WAKE AND LINGER THROUGH THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1125 AM EST...THE MAIN MORNING UPDATE CONCERNS INCLUDE ADJ TO
POPS AND SKY COVER. THE LATEST VIS IS SHOWING A DRYING WARM SECTOR
AHEAD OF THE COLD FRONT ACROSS NE GA AND THE SW/RN UPSTATE. THIS
SHOULD FILL IN A LITTLE AS THE AFTERNOON PROGRESSES WITH MOIST ADV
AND DEVELOPING CONVECTION. POPS WERE ALSO ADJ DOWN ACROSS GA...THE
UPSTATE AND INTO THE SRN NC PIEDMONT. THE LATEST HRRR COMP REFLECT
HAS A GOOD HANDLE ON THE PLACEMENT AND EVOLUTION OF THE RETURNS SEEN
ON THE 88D AND IT/S PROGS WERE BLENDED INTO THE GRIDS. MAX TEMPS
WILL BE TRICKY THIS AFTERNOON WITH THE POSSIBLE ADDED INSOL EARLY ON
OVER THE SRN ZONES...AND MAY NEED ANOTHER SIGFNT UPDATE EARLY THIS
AFTERNOON. FOR NOW WENT WITH A EVEN RATIO OF THE NAM/GFS THICKNESS
SCHEME AND BLENDED THAT WITH THE LATEST MAVMOS AND OFFICIAL
FCST.
AS OF 949 AM EST...THE OVERALL FCST IS IN GOOD SHAPE. RADAR IS
BEGINNING TO FILL IN WITH STRONGER RETURNS ACROSS THE NC PIEDMONT
AND FOOTHILLS ASSOCIATED WITH AN ULVL DIFFLUENT ZONE. ALSO...STEEP
H7/H5 LAPSE RATES ARE MAINTAINING ENOUGH CHARGE SEPARATION FOR
THUNDER ACROSS ERN TN AND THIS WILL BE MOVING INTO THE WRN NC MTNS
WITHIN THE NEXT HR. THE GRIDS ACROSS THE WRN MOST NC ZONES WERE THUS
UPDATED TO INCLUDE ISOL TSTMS.
AS OF 645 AM EST...WATER VAPOR IMAGERY SHOWS THE DEEPENING UPPER LOW
PRESSURE CENTER MOVING SE ACROSS IOWA THIS MORNING. RETURNING LOW
LEVEL MOISTURE AND ISENTROPIC LIFT WELL SE OF THIS SYSTEM IS
STARTING TO PRODUCE SOME LIGHT RADAR RETURNS FROM THE SW.
FORTUNATELY...THE CHILLY CENTRAL AND SRN MTN VALLEY TEMPS HAVE
GENERALLY REBOUNDED ABOVE THE FREEZING MARK...WITH JUST A FEW NRN
MTN LOCATIONS STILL RUNNING 30 TO 32 DEGREES. VERY SPOTTY LIGHT
FREEZING RAIN WILL BE POSSIBLE IN NRN MTN SECTIONS FOR THE NEXT
COUPLE OF HOURS...BUT WITH QPF TOO LIGHT FOR ANY ICING PROBLEMS.
OTHERWISE...THE FORECAST IS ON TRACK WITH IMPROVING LOW LEVEL
UPGLIDE MOISTURE STEADILY INCREASING ACROSS THE FORECAST AREA
THROUGH THE DAY...WITH INCREASING/EXPANDING POPS RESULTING. 850 MB
WINDS WILL SLOWLY BACK AND STRENGTHEN BY LATE AFTERNOON IN THE WARM
SECTOR ACROSS THE REGION...AND SFC BASED INSTABILITY WILL INCREASE
ENOUGH BY LATE DAY TO WARRANT A SCHC TO CHC TSTM MENTION OVER SRN
SECTIONS...AND ALSO OVER THE WRN MTNS WITH IMPROVING LAPSE RATES
ALOFT. IN ADDITION...40 TO 50 KT OF LOW LEVEL SHEAR WILL WARRANT AN
ISOLD SEVERE THREAT MENTION TOWARD EVENING IN THE SRN
PIEDMONT...WITH BL HELICITY VALUES AT OR ABOVE 500 M2/S2 CROSSING
THE REGION TOWARD 00Z.
THE STRONGEST 850 TO 500 MB DPVA SHOULD TRANSIT THE FORECAST AREA
MAINLY 00Z TO 06Z AHEAD OF THE DEEP H5 LOW PRES CENTER MOVING FROM
THE LOWER OH VALLEY THROUGH THE SRN APPALACHIANS. THE ASSOCIATED SFC
COLD FRONT WILL MOVE QUICKLY THROUGH THE REGION CENTERED AROUND
03Z...WITH PROFILES RAPIDLY BECOMING COLD ENOUGH TO SUPPORT SNOW
OVER THE HIGHER TERRAIN...AND THEN THROUGHOUT THE LOWEST VALLEYS
OVERNIGHT IN IMPROVING MOIST NW UPSLOPE FLOW. THE QUICK SHOT OF DEEP
EVENING MOISTURE WILL MOVE EAST OF THE AREA...WITH PROMINENT MID
LEVEL DRYING ARRIVING ACROSS THE FOOTHILLS AND PIEDMONT FROM THE SW
BY 06Z. HOWEVER...ADDITIONAL DEEPER MOISTURE WILL THEN WRAP SWD
BEHIND THE PASSING CYCLONE TOWARD DAYBREAK WED TO ADD TO SNOWFALL
TOTALS OVER THE WRN MTNS IN BLOSSOMING NW UPSLOPE FLOW IN THE VERY
COLD AIR. THE WINTER STORM WATCH WILL BE UPGRADED TO A
WARNING...WITH AN ADVISORY TIER ADDED FOR BUNCOMBE AND MACON. IN
ADDITION...EXPECT VERY WINDY CONDITIONS OVER THE MTNS WITH THE COLD
ADVECTION AND 50 KT OF 850 MB FLOW. WIND HAZARDS WILL BE WRAPPED
INTO THE WINTER STORM PRODUCTS...EXCEPT FOR A STANDALONE WIND
ADVISORY FOR MCDOWELL MTNS TO CALDWELL MTNS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 1 PM TUESDAY...NORTHWEST FLOW ALOFT WILL DOMINATE THE SHORT
RANGE PERIOD AS A CUTOFF UPPER LOW OFF THE EAST COAST IS BLOCKED
FROM ESCAPE TO THE EAST. ANOTHER UPPER LOW/SHORT WAVE WILL BE
ASSIMILATED THURSDAY NIGHT AND FRIDAY...BUT THIS WILL MOVE PAST WELL
TO OUR NORTHEAST. THUS...FOR THE MOST PART...WE WILL REMAIN UNDER
THE INFLUENCE OF COLD HIGH PRESSURE BUILDING IN FROM THE NORTHWEST
THROUGH FRIDAY. THE PRODUCTION OF SNOW ALONG THE TN BORDER WILL
CONTINUE WEDNESDAY NIGHT AS MOISTURE MOVES DOWN FROM THE NW...BUT
THIS SHOULD WANE ON THURSDAY MORNING AS THE MOISTURE PULLS OUT.
PRECIP CHANCES START OUT LIKELY ON THE TN BORDER WEDNESDAY EVE AND
THEN TAPER OFF FROM THERE...ENDING BY MIDDAY ON THURSDAY. IT STILL
LOOKS LIKE THERE IS THE POTENTIAL FOR ANOTHER INCH OR TWO WEDNESDAY
NIGHT...SO THE WARNING CONTINUATION THROUGH SUNRISE THURSDAY LOOKS
TO BE RIGHT ON TRACK. THIS ACTIVITY IS NOT EXPECTED TO MAKE IT EAST
OF THE BLUE RIDGE. TEMPERATURES SHOULD MODERATE THROUGH THE
PERIOD...WITH HIGHS THURSDAY ABOUT FIVE DEGREES WARMER THAN
WEDNESDAY...THEN ANOTHER CATEGORY OR SO WARMER AGAIN ON FRIDAY. LOW
TEMPS WILL ALSO SHOW A MODERATING TREND...ALTHO NOT AS PRONOUNCED.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 215 AM EST TUESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
FRIDAY WITH A COMPLEX UPPER LOW GRADUALLY MOVING OFF THE NEW ENGLAND
COAST AND UPPER RIDGING MOVING OVER THE CAROLINAS. RIDGING IS
EXPECTED TO LINGER THRU MOST OF THE WEEKEND WHILE ANOTHER DEEP UPPER
TROF DRIFTS ACROSS THE WESTERN CONUS. THE LONG RANGE MODELS BEGIN TO
DIVERGE WRT TO THE EVOLUTION OF THIS TROF LATE IN THE WEEKEND WITH
THE ECMWF CLOSING OFF A VERY LARGE AND BROAD CLOSED H5 LOW AND VERY
GRADUALLY MOVING THE LOW TOWARDS THE FCST AREA. ANY IMPACTS ON OUR
SENSIBLE WX WOULD NOT BE SEEN UNTIL LATER NEXT WEEK. ON THE OTHER
HAND...THE MORE PROGRESSIVE GFS DOESNT QUITE CLOSE THE LOW OFF FROM
THE NORTHERN STREAM FLOW AND AS A RESULT...BRINGS A HEALTHY AMOUNT
OF H5 PVA TO OUR DOORSTEP BY LATE MONDAY INTO EARLY TUESDAY. FOR THE
TIME BEING...MOST OF THE GUIDANCE IS FAVORING A LESS PROGRESSIVE
SOLUTION WITH PERSISTENT UPPER RIDGING IN PLACE THRU DAY 7.
AT THE SFC...COOL CANADIAN HIGH PRESSURE MOVES BACK INTO THE AREA ON
THURS AND IS EXPECTED TO LINGER THRU THE WEEKEND. THE MODELS INDICATE
A LOW WILL DEEPEN EAST OF THE ROCKIES ON SUNDAY AND DRIFT EASTWARD
EARLY NEXT WEEK. THE SLOWER ECMWF SOLUTION KEEPS THE LOW AND ITS
COLD FRONT TO OUR WEST UNTIL THE VERY END OF THE PERIOD WHILE THE
FASTER GFS MOVES THE FRONT OVER THE CWFA ON MONDAY. EITHER WAY...LOW
LVL FLOW SHOULD BECOME MORE SLY AND MOISTEN BY EARLY NEXT WEEK AS
THE HIGH SLIDES FARTHER EAST. I HAVE POPS RAMPING UP TO SOLID CHANCE
OVER MOST OF THE CWFA BY TUES MORNING WITH THE HIGHEST VALUES OVER
THE WESTERN ZONES. OTHERWISE...THE PERIOD WILL BE DRY WITH TEMPS
WARMING THRU THE WEEKEND AND THEN LEVELING OFF EARLY NEXT WEEK. BY
SUNDAY...HIGHS ARE EXPECTED TO REACH THE MID 60S FOR THE LOWER
ELEVATIONS AND UPPER 50S TO LOWER 60S FOR THE HIGHER TERRAIN.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AT KCLT...UNEXPECTED CLEARING SKIES ARE MAKING HEADWAY TOWARD THE
TERMINAL AND THIS WILL BE METWATCHED FOR A PROBABLE AMD TO VFR OVER
THE NEXT COUPLE HRS. POPS HAVE BEEN ADJ DOWN AS WELL WITH -SHRA OR
DEEPER CONVECTION NOT ANTICIPATED TILL 20Z. THE TIMING OF THIS IS ALSO
SUSPECT AND WILL NEED TO BE MONITORED. A STRONG LLVL JET WILL CROSS
THE TERMINAL AFT 00Z AND THERE COULD BE SOME WS ISSUES NOT
ASSOCIATED WITH TSTMS OR TALL CONVECTION. AFTER FROPA ARD 03Z...SFC
GUSTS WILL PICK UP AND REMAIN THROUGH THE END OF THE TAF PERIOD. VFR
CIGS RETURN POST FROPA.
AT KAVL...MVFR CIGS WILL PERSIST THROUGH MOST OF THE PERIOD AS COLD
FRONT APPROACHES FROM THE WEST. FROPA IS AFT 00Z...BUT MOIST FLOW UP
THE FRENCH BROAD VALLEY WILL ENABLE LOW CIGS. A RETURN TO VFR IS
EXPECT AFT 11Z WITH LLVL UPSTREAM MOISTURE WANING. MODERATE SFC WIND
GUSTS WILL DEVELOP AFT FROPA AS WELL AND REMAIN THROUGH THE TAF
PERIOD.
ELSEWHERE...A LARGE ARE OF DRYING HAS DEVELOPED IN THE WARM SECTOR
AND EXPECT KAND TO REMAIN VFR TILL PERIODS OF CONVECTION APPROACHE
AFT 20Z. KGSP AND KGMU REMAIN RIGHT ON THE BORDER OF THE SCT
CLOUDS...BUT WILL KEEP MVFR FOR NOW BASED ON VIS SAT LOOP. A 3 HR
TEMPO THUNDER WAS INCLUDED AT KAND BEGINNING AT 00Z WITH SBCAPE
VALUES APPROACHING 400 J/KG BY THAT TIME. FROPA WILL OCCUR AND CIGS
SHOULD RETURN TO VFR AT ALL SITES AFT 04Z. WINDS WILL RESPOND TO A
STRONG P/GRAD BEHIND THE FRONT AND DOWNWARD MIXING AND ENABLE
MODERATE GUSTS THROUGH THE PERIOD.
OUTLOOK...WINDY NW FLOW CONDITIONS WILL PERSIST WED INTO WED NIGHT
AS STRONG LOW PRES PULLS AWAY OFF THE MID ATLANTIC COAST. LINGERING
RESTRICTIONS AND NEARBY SHSN WILL CONTINUE TO IMPACT KAVL THROUGH
WED. STRONG DRY RIDGING WILL THEN DEVELOP THU THROUGH THE WEEKEND.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 92% HIGH 81% HIGH 100% HIGH 100%
KGSP HIGH 86% HIGH 94% HIGH 100% HIGH 100%
KAVL HIGH 80% MED 73% MED 71% HIGH 100%
KHKY HIGH 95% HIGH 82% HIGH 100% HIGH 100%
KGMU HIGH 85% HIGH 88% HIGH 100% HIGH 100%
KAND HIGH 81% HIGH 94% 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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EST WEDNESDAY
NIGHT FOR NCZ501-503-505.
WINTER STORM WARNING FROM 7 PM THIS EVENING TO 6 AM EST
THURSDAY FOR NCZ033-048>052-058-059.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO MIDNIGHT EST
WEDNESDAY NIGHT FOR NCZ053-062.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...HG/SBK
SHORT TERM...NED
LONG TERM...JPT
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1136 AM EST TUE MAR 5 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL PASS OVER THE AREA TONIGHT AND EARLY
WEDNESDAY BRINGING RAIN AND SNOW SHOWERS TO THE WESTERN CAROLINAS.
DRIER HIGH PRESSURE WILL RETURN IN ITS WAKE AND LINGER THROUGH THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1125 AM EST...THE MAIN MORNING UPDATE CONCERNS INCLUDE ADJ TO
POPS AND SKY COVER. THE LATEST VIS IS SHOWING A DRYING WARM SECTOR
AHEAD OF THE COLD FRONT ACROSS NE GA AND THE SW/RN UPSTATE. THIS
SHOULD FILL IN A LITTLE AS THE AFTERNOON PROGRESSES WITH MOIST ADV
AND DEVELOPING CONVECTION. POPS WERE ALSO ADJ DOWN ACROSS GA...THE
UPSTATE AND INTO THE SRN NC PIEDMONT. THE LATEST HRRR COMP REFLECT
HAS A GOOD HANDLE ON THE PLACEMENT AND EVOLUTION OF THE RETURNS SEEN
ON THE 88D AND IT/S PROGS WERE BLENDED INTO THE GRIDS. MAX TEMPS
WILL BE TRICKY THIS AFTERNOON WITH THE POSSIBLE ADDED INSOL EARLY ON
OVER THE SRN ZONES...AND MAY NEED ANOTHER SIGFNT UPDATE EARLY THIS
AFTERNOON. FOR NOW WENT WITH A EVEN RATIO OF THE NAM/GFS THICKNESS
SCHEME AND BLENDED THAT WITH THE LATEST MAVMOS AND OFFICIAL
FCST.
AS OF 949 AM EST...THE OVERALL FCST IS IN GOOD SHAPE. RADAR IS
BEGINNING TO FILL IN WITH STRONGER RETURNS ACROSS THE NC PIEDMONT
AND FOOTHILLS ASSOCIATED WITH AN ULVL DIFFLUENT ZONE. ALSO...STEEP
H7/H5 LAPSE RATES ARE MAINTAINING ENOUGH CHARGE SEPARATION FOR
THUNDER ACROSS ERN TN AND THIS WILL BE MOVING INTO THE WRN NC MTNS
WITHIN THE NEXT HR. THE GRIDS ACROSS THE WRN MOST NC ZONES WERE THUS
UPDATED TO INCLUDE ISOL TSTMS.
AS OF 645 AM EST...WATER VAPOR IMAGERY SHOWS THE DEEPENING UPPER LOW
PRESSURE CENTER MOVING SE ACROSS IOWA THIS MORNING. RETURNING LOW
LEVEL MOISTURE AND ISENTROPIC LIFT WELL SE OF THIS SYSTEM IS
STARTING TO PRODUCE SOME LIGHT RADAR RETURNS FROM THE SW.
FORTUNATELY...THE CHILLY CENTRAL AND SRN MTN VALLEY TEMPS HAVE
GENERALLY REBOUNDED ABOVE THE FREEZING MARK...WITH JUST A FEW NRN
MTN LOCATIONS STILL RUNNING 30 TO 32 DEGREES. VERY SPOTTY LIGHT
FREEZING RAIN WILL BE POSSIBLE IN NRN MTN SECTIONS FOR THE NEXT
COUPLE OF HOURS...BUT WITH QPF TOO LIGHT FOR ANY ICING PROBLEMS.
OTHERWISE...THE FORECAST IS ON TRACK WITH IMPROVING LOW LEVEL
UPGLIDE MOISTURE STEADILY INCREASING ACROSS THE FORECAST AREA
THROUGH THE DAY...WITH INCREASING/EXPANDING POPS RESULTING. 850 MB
WINDS WILL SLOWLY BACK AND STRENGTHEN BY LATE AFTERNOON IN THE WARM
SECTOR ACROSS THE REGION...AND SFC BASED INSTABILITY WILL INCREASE
ENOUGH BY LATE DAY TO WARRANT A SCHC TO CHC TSTM MENTION OVER SRN
SECTIONS...AND ALSO OVER THE WRN MTNS WITH IMPROVING LAPSE RATES
ALOFT. IN ADDITION...40 TO 50 KT OF LOW LEVEL SHEAR WILL WARRANT AN
ISOLD SEVERE THREAT MENTION TOWARD EVENING IN THE SRN
PIEDMONT...WITH BL HELICITY VALUES AT OR ABOVE 500 M2/S2 CROSSING
THE REGION TOWARD 00Z.
THE STRONGEST 850 TO 500 MB DPVA SHOULD TRANSIT THE FORECAST AREA
MAINLY 00Z TO 06Z AHEAD OF THE DEEP H5 LOW PRES CENTER MOVING FROM
THE LOWER OH VALLEY THROUGH THE SRN APPALACHIANS. THE ASSOCIATED SFC
COLD FRONT WILL MOVE QUICKLY THROUGH THE REGION CENTERED AROUND
03Z...WITH PROFILES RAPIDLY BECOMING COLD ENOUGH TO SUPPORT SNOW
OVER THE HIGHER TERRAIN...AND THEN THROUGHOUT THE LOWEST VALLEYS
OVERNIGHT IN IMPROVING MOIST NW UPSLOPE FLOW. THE QUICK SHOT OF DEEP
EVENING MOISTURE WILL MOVE EAST OF THE AREA...WITH PROMINENT MID
LEVEL DRYING ARRIVING ACROSS THE FOOTHILLS AND PIEDMONT FROM THE SW
BY 06Z. HOWEVER...ADDITIONAL DEEPER MOISTURE WILL THEN WRAP SWD
BEHIND THE PASSING CYCLONE TOWARD DAYBREAK WED TO ADD TO SNOWFALL
TOTALS OVER THE WRN MTNS IN BLOSSOMING NW UPSLOPE FLOW IN THE VERY
COLD AIR. THE WINTER STORM WATCH WILL BE UPGRADED TO A
WARNING...WITH AN ADVISORY TIER ADDED FOR BUNCOMBE AND MACON. IN
ADDITION...EXPECT VERY WINDY CONDITIONS OVER THE MTNS WITH THE COLD
ADVECTION AND 50 KT OF 850 MB FLOW. WIND HAZARDS WILL BE WRAPPED
INTO THE WINTER STORM PRODUCTS...EXCEPT FOR A STANDALONE WIND
ADVISORY FOR MCDOWELL MTNS TO CALDWELL MTNS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 3 AM MONDAY...BY 12Z WED...SHORT RANGE MODELS INDICATE THAT
THE H5 LOW WILL BE CENTERED OVER KGSO WITH THE SFC LOW CENTERED OVER
THE TIDEWATER OF VA. WED MORNING...LLVL FLOW ACROSS THE TN BORDER
COUNTIES OF NC IS EXPECTED TO FAVOR WNW DIRECTION...A LITTLE WEST OF
OPTIMAL NWFS GENERATION. HOWEVER...THE CLOSED LOW AND SFC LOW WILL
TRACK EAST DURING THE DAY...RESULTING IN VEERING LLVL FLOW ACROSS
THE FORECAST AREA. WIND DIRECTION AND SPEEDS ACROSS THE SOUTHERN
APPALACHIAN REGION ARE FORECAST TO BECOME VERY FAVORABLE FOR NWFS BY
MID DAY WEDNESDAY. FORECAST SOUNDINGS ACROSS NC MTNS AND EASTERN TN
SITES INDICATE THAT THE LAYER OF SATURATED AIR SHOULD EXTEND FROM
THE BL TO H65 EARLY WEDNESDAY...GRADUALLY FADING TO A H9 TO H75 BY
LATE AFTERNOON. BASED ON WIND TIMING...MOISTURE CONTENT...AND
TEMPERATURE PROFILES...CONDITIONS APPEAR VERY FAVORABLE FOR
ACCUMULATING NWFS WEDNESDAY MORNING UNTIL THE EARLY AFTERNOON.
DURING THIS TIME WINDOW...I WILL INDICATE HOURLY QPF AMOUNTS FROM
0.03 INCHES ALONG THE TN LINE. SLR VALUES OF 12 TO 14 TO 1 WILL
RESULT IN HOURLY SNOWFALL RATES FROM 0.25 TO 0.4 OF AN INCH ACROSS
THE FAVORED UPSLOPE AREAS. TOTAL DAYLIGHT SNOWFALL ACROSS THE MTNS
ON WEDNESDAY IS FORECAST TO RANGE FROM NEAR 4 INCHES ALONG THE SPINE
OF THE APPALACHIANS TO 1 TO 3 INCHES ACROSS THE TN BORDER COUNTIES.
IN ADDITION...WINDS ACROSS THE MTNS WILL BECOME QUITE GUSTY THROUGH
THE DAY...REACHING WIND ADVISORY CRITERIA LEVELS. EAST OF THE
MTNS...CONDITIONS WILL REMAIN BREEZY...DRY...WITH DECREASING SKY
COVER. HIGHS ARE FORECAST TO RANGE FROM NEAR 40 WITHIN THE MTN
VALLEYS TO NEAR 50 EAST.
WEDNESDAY NIGHT...ACCUMULATING SNOWFALL WILL GRADUALLY DISSIPATE
ACROSS THE NC MTNS AS MOISTURE AND WINDS DECREASE. HOWEVER...THE
FAVORED UPSLOPE AREAS MAY SEE AN ADDITIONAL INCH OF SNOW. MIN
TEMPERATURES ARE FORECAST TO RANGE FROM THE 20S ACROSS THE MTNS TO
AROUND FREEZING EAST. CANADIAN HIGH PRESSURE WILL BEGIN TO BUILD
OVER THE REGION ON THURSDAY. MID LEVEL HEIGHTS AND H85 TEMPERATURES
WILL SLOWLY INCREASE THROUGH THE DAY. THE COMBINATION OF GOOD
INSOLATION AND RISING THICKNESSES SHOULD ALLOW TEMPERATURES TO WARM
SIGNIFICANTLY FROM WEDNESDAY...BUT FALLING SHORT OF NORMALS BY 5 TO
7 DEGREES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 215 AM EST TUESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
FRIDAY WITH A COMPLEX UPPER LOW GRADUALLY MOVING OFF THE NEW ENGLAND
COAST AND UPPER RIDGING MOVING OVER THE CAROLINAS. RIDGING IS
EXPECTED TO LINGER THRU MOST OF THE WEEKEND WHILE ANOTHER DEEP UPPER
TROF DRIFTS ACROSS THE WESTERN CONUS. THE LONG RANGE MODELS BEGIN TO
DIVERGE WRT TO THE EVOLUTION OF THIS TROF LATE IN THE WEEKEND WITH
THE ECMWF CLOSING OFF A VERY LARGE AND BROAD CLOSED H5 LOW AND VERY
GRADUALLY MOVING THE LOW TOWARDS THE FCST AREA. ANY IMPACTS ON OUR
SENSIBLE WX WOULD NOT BE SEEN UNTIL LATER NEXT WEEK. ON THE OTHER
HAND...THE MORE PROGRESSIVE GFS DOESNT QUITE CLOSE THE LOW OFF FROM
THE NORTHERN STREAM FLOW AND AS A RESULT...BRINGS A HEALTHY AMOUNT
OF H5 PVA TO OUR DOORSTEP BY LATE MONDAY INTO EARLY TUESDAY. FOR THE
TIME BEING...MOST OF THE GUIDANCE IS FAVORING A LESS PROGRESSIVE
SOLUTION WITH PERSISTENT UPPER RIDGING IN PLACE THRU DAY 7.
AT THE SFC...COOL CANADIAN HIGH PRESSURE MOVES BACK INTO THE AREA ON
THURS AND IS EXPECTED TO LINGER THRU THE WEEKEND. THE MODELS INDICATE
A LOW WILL DEEPEN EAST OF THE ROCKIES ON SUNDAY AND DRIFT EASTWARD
EARLY NEXT WEEK. THE SLOWER ECMWF SOLUTION KEEPS THE LOW AND ITS
COLD FRONT TO OUR WEST UNTIL THE VERY END OF THE PERIOD WHILE THE
FASTER GFS MOVES THE FRONT OVER THE CWFA ON MONDAY. EITHER WAY...LOW
LVL FLOW SHOULD BECOME MORE SLY AND MOISTEN BY EARLY NEXT WEEK AS
THE HIGH SLIDES FARTHER EAST. I HAVE POPS RAMPING UP TO SOLID CHANCE
OVER MOST OF THE CWFA BY TUES MORNING WITH THE HIGHEST VALUES OVER
THE WESTERN ZONES. OTHERWISE...THE PERIOD WILL BE DRY WITH TEMPS
WARMING THRU THE WEEKEND AND THEN LEVELING OFF EARLY NEXT WEEK. BY
SUNDAY...HIGHS ARE EXPECTED TO REACH THE MID 60S FOR THE LOWER
ELEVATIONS AND UPPER 50S TO LOWER 60S FOR THE HIGHER TERRAIN.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AT KCLT...UPSTATE SC OBS TO THE SW HAVE SHOWN A MORE RAPID TREND
DOWNWARD TOWARD MVFR THIS MORNING...AND THE LOWERING THROUGH VFR
TOWARD MVFR AT KCLT WILL BE HASTENED AS WELL. RAIN OR SHOWER CHANCES
WILL IMPROVE THROUGH THE AFTERNOON AS UPGLIDE MOISTURE INCREASES.
THERE WILL BE IMPROVING SFC BASED INSTABILITY VERY LATE IN THE
DAY...BUT WITH CONFIDENCE ON ANY DEEPER CONVECTION AHEAD OF THE
FRONT STILL TOO LOW TO MENTION ANY TSTMS FOR NOW. EXPECT AT LEAST
MODERATE RAIN SHOWERS ALONG WITH IFR CIGS AND GUSTIER WINDS AT OR
BEFORE 19Z. LIGHT SRLY WINDS THIS MORNING WILL SLOWLY INCREASE
THROUGH THE DAY...WITH GUSTS DEVELOPING THIS AFTERNOON AND
STRENGTHENING TOWARD EVENING. EXPECT A RAPID RECOVERY TO VFR BY 06Z
WITH A DRY PUNCH WORKING IN POST FROPA.
AT KAVL...CIG LOWERING TREND THROUGH VFR IS ALREADY UNDERWAY THIS
MORNING...AND THE TRANSITION TO MVFR BY 15Z AND IFR BY 19Z HAS BEEN
MOVED UP ALONG WITH PRECIP TIMING IN UPGLIDE. WITH DAYBREAK TEMPS
AROUND 35 DEGREES...NO FREEZING RAIN IS CURRENTLY EXPECTED WITH THE
ONSET OF THE STEADIER RAIN. MVFR CIGS WILL TREND DOWN TO IFR THROUGH
LATE AFTN AS THE RAIN/SHOWERS INCREASE AND SRLY GUSTS DEVELOP. A
SHARP WIND SHIFT TO NW IS EXPECTED WITH FROPA BY 02Z...CREATING
WINDY CONDITIONS AND A GRADUAL MIXOVER TO SNOW SHOWERS TOWARD THE
END OF THE PERIOD.
ELSEWHERE...LOWERING VFR CLOUDS WILL TRANSITION QUICKLY TO MVFR FROM
S TO N AT THE FOOTHILL SITES THIS MORNING AS STEADIER LIGHT RAIN
SPREADS IN ON UPGLIDE. SHOWER COVERAGE/INTENSITY SHOULD INCREASE
THROUGH THE EARLY AFTERNOON...WITH ISOLD TO SCT TSTMS POSSIBLE OVER
SRN SECTIONS LATER THIS AFTN OR EARLY EVENING...ESPECIALLY NEAR
KAND. SRLY WINDS WILL INCREASE THROUGH THE AFTN AND BECOME
GUSTY...WITH A SHARP SHIFT WESTERLY DURING THE EVENING HOURS WITH
FROPA. A DRY SLOT ARRIVING FROM THE SW WILL ALLOW CIG CONDITIONS TO
IMPROVE AT THE UPSTATE TAF SITES...BUT WITH RESTRICTIONS LINGERING
AT KHKY THROUGH AT LEAST 06Z.
OUTLOOK...WINDY NW FLOW CONDITIONS WILL PERSIST WED INTO WED NIGHT
AS STRONG LOW PRES PULLS AWAY OFF THE MID ATLANTIC COAST. LINGERING
RESTRICTIONS AND NEARBY SHSN WILL CONTINUE TO IMPACT KAVL THROUGH
WED. STRONG DRY RIDGING WILL THEN DEVELOP THU THROUGH THE WEEKEND.
CONFIDENCE TABLE...
16-22Z 22-04Z 04-10Z 10-16Z
KCLT MED 68% MED 66% HIGH 93% HIGH 100%
KGSP MED 75% HIGH 82% HIGH 93% HIGH 100%
KAVL MED 70% HIGH 87% HIGH 100% HIGH 100%
KHKY MED 74% MED 63% HIGH 93% HIGH 100%
KGMU HIGH 83% MED 74% HIGH 93% HIGH 100%
KAND HIGH 85% MED 74% 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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EST WEDNESDAY
NIGHT FOR NCZ501-503-505.
WINTER STORM WARNING FROM 7 PM THIS EVENING TO 6 AM EST
THURSDAY FOR NCZ033-048>052-058-059.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO MIDNIGHT EST
WEDNESDAY NIGHT FOR NCZ053-062.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...HG/SBK
SHORT TERM...NED
LONG TERM...JPT
AVIATION...HG/SBK
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
343 PM CST TUE MAR 5 2013
.SHORT TERM...
TONIGHT...FORECAST CONFIDENCE MEDIUM.
THE INVERTED TROUGH AXIS STRETCHED FROM SURFACE LOW PRESSURE
CENTERED IN EASTERN KENTUCKY NORTHWESTWARD ACROSS NORTHERN IL AND
SOUTHEAST MN AT 3 PM THIS AFTERNOON. THE UPPER LOW OVER IOWA WILL
SHIFT SOUTHEAST OVER SOUTHERN IL AND THROUGH THE OHIO RIVER VALLEY
TONIGHT. THE BAND OF MODERATE TO HEAVY SNOW PARKED OVER SOUTHERN WI
FOR MOST OF THE DAY IS SLOWLY SHRINKING AND SLIPPING SOUTHWARD LATE
THIS AFTERNOON. DRY AIR FROM THE NORTHEAST IS PROGRESSING INTO THE
CENTRAL FORECAST AREA AND CAUSING RISING CLOUD HEIGHTS...INCREASED
VISIBILITIES AND MUCH SMALLER SNOW CRYSTALS. WE CUT BACK
SIGNIFICANTLY ON POPS AND EXPECTED ADDITIONAL SNOWFALL FOR THE REST
OF THE AFTERNOON AND EVENING DUE TO THIS DRY AIR.
WE CONTINUE TO SEE LIGHT RETURNS OVER SHEBOYGAN AND NORTHWARD ON
RADAR...AND SURFACE OBSERVATIONS CONTINUE TO SHOW NO WEATHER MEANING
THAT SNOW ALOFT IS NOT HITTING THE GROUND. RAP SOUNDINGS VERIFY THIS
BY SHOWING A DRY LAYER AROUND 5000 FEET. THERE IS A POSSIBILITY THAT
THIS DRY LAYER WILL SATURATE THIS EVENING AND SNOW COULD STILL
DEVELOP IN THE NORTHEAST FORECAST AREA...BUT AMOUNTS WILL BE LIGHT.
WEDNESDAY...FORECAST CONFIDENCE MEDIUM.
THE SURFACE AND UPPER LOWS WILL MOVE EASTWARD OVERNIGHT AND
WEDNESDAY. HIGH RH AND LOW LEVEL CONVERGENCE ARE FORECAST TO SIT
ALONG THE LAKE MICHIGAN SHORELINE. DELTA TS WILL BE LESS THAN
9C...WHICH IS NOT FAVORABLE FOR MEASURABLE LAKE EFFECT SNOW. CUT
POPS AND CHANGED THE WEATHER TO SCATTERED FLURRIES FOR THE LAKESHORE
COUNTIES ON WED.
ELSEWHERE...WEAK CYCLONIC FLOW ALOFT WILL ALLOW FOR PLENTY OF CLOUDS
THROUGH THE DAY. CANNOT RULE OUT A FEW FLURRIES AS WELL. HIGH TEMPS
EXPECTED AROUND 30 AND A LITTLE WARMER NEAR THE LAKESHORE.
WEDNESDAY NIGHT THROUGH FRIDAY...
A MERIDIONAL FLOW IN THE SRN PORTION OF THE SPLIT JET STREAM OVER
THE UNITED STATES WILL RESULT IN UPPER RIDGING SLOWLY MOVING FROM
THE GREAT PLAINS TO THE MS RIVER VALLEY DURING THIS PERIOD. UPPER
TROUGHS OVER THE WESTERN AND EASTERN PORTIONS OF THE COUNTRY WILL
BE PRESENT DURING THIS TIME. THIS YIELDS A N-S POLAR HIGH PRESSURE
AREA OVER THE BADGER STATE. THE HIGH WILL MOVE EWD FOR FRIDAY WITH
LGT SLY WINDS AND WARM ADVECTION EXPECTED. BELOW NORMAL TEMPS ARE
EXPECTED WITH SOME WARMING FOR FRIDAY.
.LONG TERM...
SATURDAY THROUGH TUESDAY...FORECAST CONFIDENCE LOW TO MEDIUM
A LARGE UPPER LOW OVER THE DESERT SW ON SAT WILL TRACK INTO THE
CENTRAL PLAINS ON SUN AND THEN BETWEEN THE OHIO RIVER VALLEY AND
GREAT LAKES FOR EARLY NEXT WEEK. MODELS DIFFER ON EVOLUTION AND
TIMING BUT MILDER TEMPS WILL OCCUR WITH CHANCES OF RAIN/SNOW
THROUGH THIS PERIOD.
&&
.AVIATION/00Z TAFS/...
DRY AIR IS ERODING AWAY THE HIGHER SNOW RATES IN THE NORTH HALF OF
SOUTHERN WI AS WINDS TURN NORTHEAST. CIGS ARE RISING AND VSBYS ARE
IMPROVING. THIS AFFECTED MILWAUKEE AT 21Z AND EARLIER AT WAUKESHA.
THE BAND OF STEADY SNOW OVER MADISON IS EXPECTED TO SLIP SOUTH LATE
THIS AFTERNOON. NOT SURE IF THAT DRY AIR WILL AFFECT KENOSHA.
THE SNOW WILL TAPER OFF FROM NORTHWEST TO SOUTHEAST THIS EVENING AND
DIMINISH FOR ALL BUT SOUTHEAST WI OVERNIGHT. CIGS/VSBYS WILL LIFT TO
MVFR...BUT CLOUDS SHOULD REMAIN WELL INTO WEDNESDAY.
WINDS BE GENERALLY NORTHEAST AND GUST AT TIMES TO 25KTS AT MKE AND
20KTS AT MADISON. LOOK FOR WINDS TO CONTINUE BACKING TO THE NORTH
THIS EVENING WITH WINDS GRADUALLY DIMINISHING TONIGHT. DRIFTING AND
POSSIBLY BLOWING SNOW CAN BE EXPECTED AT TIMES.
&&
.MARINE...SMALL CRAFT IN EFFECT THROUGH WEDNESDAY AFTERNOON EVENING
WITH PERSISTENT NNE WINDS AND HIGH WAVES. WINDS AND WAVES WILL
DIMINISH AS HIGH PRESSURE MOVES OVERHEAD BY THURSDAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ064-
070>072.
WINTER STORM WARNING UNTIL 9 PM CST THIS EVENING FOR WIZ046-056-
057-062-063-067>069.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ047-
058-065-066.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM CST WEDNESDAY FOR LMZ645-646.
SMALL CRAFT ADVISORY UNTIL 4 PM CST WEDNESDAY FOR LMZ643-644.
&&
$$
TONIGHT/WEDNESDAY AND AVIATION/MARINE...MRC
WEDNESDAY NIGHT THROUGH TUESDAY...GEHRING