Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/19/13
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
901 PM PDT MON MAR 18 2013
.DISCUSSION...AS OF 9:00 PM PDT MONDAY...A SIGNIFICANT CHANGE
IN THE WEATHER PATTERN IS DEVELOPING TONIGHT WITH WARM FRONTAL
PROCESSES PRIMING THE ATMOSPHERE FOR THE INCOMING RAIN. DEW POINTS
ARE RISING...THE 00Z SOUNDING SHOWS A MOISTENING ATMOSPHERE AND
THE AMSU TPW SHOWS 0.75 TO 0.83 INCHES OF PRECIPITABLE WATER JUST
OFF THE NORTHERN AND CENTRAL CALIFORNIA COAST.
LOW CONFIDENCE IN THE CURRENT MODEL SOLUTIONS AS THEY ARE NOT
MATCHING UP TO WHAT IS CURRENTLY BEING OBSERVED. DOPPLER RADAR IS
CURRENTLY PICKING UP RETURNS OFF THE SONOMA AND MARIN COUNTY
COASTS WHICH WAS NOT DEPICTED BY THE GFS...NAM OR EURO. THE MOST
CURRENT HIGH RESOLUTION MODEL PRESENTLY AVAILABLE TO US...THE
RAP...DEPICT AN AREA OF MOISTURE APPROACHING THE COAST THIS
EVENING AND INTO TONIGHT. HOWEVER THE MOISTURE GRADUALLY
DISSIPATING AS IT NEARS THE COAST OVERNIGHT. THE RAP SHOWS LIGHT
PRECIP POSSIBLE OVER THE NORTHERN BORDER OF SONOMA COUNTY. WOULD
NOT RULE IT OUT AT THIS POINT. WILL NEED TO CLOSELY MONITOR THE
EVOLUTION OF THE APPROACHING LOW AND ASSOCIATED COLD FRONT
OVERNIGHT AND MAY NEED TO OVERHAUL THE FORECAST.
WILL HOLD OFF ON MAKING ANY SIGNIFICANT CHANGES TO THE FORECAST AND
WILL CONTINUE TO MONITOR.
FROM PREVIOUS DISCUSSION...HIGH CLOUDS CONTINUE TO STREAM
OVERHEAD AS MID/UPPER LEVEL MOISTURE CONTINUES TO FLOW THROUGH THE
"DIRTY RIDGE". WATER VAPOR IMAGERY IS INDC TWO SYSTEMS THAT WILL
HAVE AN EFFECT ON THE DISTRICTS WEATHER THE NEXT COUPLE OF
DAYS...ONE SYSTEM IS CENTERED NEAR 37/147 AND THE OTHER ONE IS
NEAR 57/150. THE SOUTHERN SYSTEM IS ENTRAINING SUBTROPICAL
MOISTURE WITH THE BLENDED AMSU SSM/I DATA INDC AS MUCH AS 1.8
INCHES OF TPW NEAR 26/142.
MODELS HAVE TRENDED SLOWER WITH THESE SYSTEMS AS WELL AS KEEPING
THEM OUT OF PHASE. THE NORTHERN SYSTEM WILL MOVE INTO THE PACIFIC
NORTHWEST WHEREAS THE SOUTHERN SYSTEM WILL WEAKEN AS IT MOVES TO
THE COAST. SINCE THE BEST DYNAMICS WILL BE WELL TO THE NORTH
OROGRAPHICS WILL BE THE MAIN LIFTING MECHANISM FOR RAIN. AS OF
NOW...IT LOOKS LIKE LIGHT RAIN WILL DEVELOP IN THE NORTH BAY
TUESDAY AFTN...SPREADING SOUTH TUESDAY NIGHT INTO WEDNESDAY. POST
FRONTAL SHOWERS WILL CONTINUE WEDNESDAY AFTN AND END EARLY
WEDNESDAY EVENING. RAINFALL TOTALS WILL BE LIGHT ACROSS THE
DISTRICT...WITH SOME LOCATIONS IN INTERIOR MONTEREY AND SAN BENITO
COUNTIES POSSIBLY NOT SEEING ANY RAIN AT ALL. THE WETTEST
LOCATIONS...IN THE NORTH BAY MOUNTAINS COULD GET AS MUCH AS 0.75
INCHES TOTAL...NOT VERY SIGNIFICANT. VALLEY LOCATIONS WILL GET
LESS THAN 0.50 INCHES OF RAIN TOTAL. BASICALLY...THIS WILL BE A
HIGH POP LOW QPF EVENT.
RIDGING WILL BUILD IN RAPIDLY THURSDAY...AND CONTINUING RIGHT INTO
THE EARLY PORTIONS OF NEXT WEEK. THIS WILL RESULT IN DRY WEATHER
WITH ABOVE NORMAL TEMPERATURES.
&&
.AVIATION...AS OF 5:20 PM PDT MONDAY...PLENTY OF HIGH CLOUDS
ACROSS OUR AREA NOW WELL IN ADVANCE OF AN APPROACHING PACIFIC STORM.
ONLY PROBLEM SPOTS TONIGHT ARE EXPECTED AROUND THE NORTH BAY WHERE
REDUCED CIGS/VIS WILL CREATE LIFR/IFR CONDITIONS. RAIN MOVES IN
LATE TUESDAY AFTERNOON TO EARLY TUESDAY EVENING. WINDS WILL MOSTLY
NOT BE A FACTOR ALTHOUGH THEY WILL PICK UP IN MANY SPOTS THIS
EVENING AS A SHORTWAVE TROF MOVES THROUGH. MODERATE CONFIDENCE.
VICINITY OF KSFO....WINDS EXPECTED TO PICK UP THIS EVENING DUE TO
THE TROF PASSAGE. FEEL CONDITIONS TUESDAY MORNING WILL BE SIMILAR
TO THIS MORNING -- SO WE SHOULD BE FREE OF LOW CLOUDS/FOG. RAIN
IMPACTS THE TERMINAL A BIT AFTER 0Z WEDNESDAY. MODERATE
CONFIDENCE.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...TOUGH CALL FOR MONTEREY BAY WITH THE
POTENTIAL FOR LOW CLOUDS/FOG TO RETURN. HOWEVER, FOR NOW WILL KEEP
THE TAFS GOING VFR THROUGH THE PERIOD ESPECIALLY WITH THE FLOW
FORECAST TO SWITCH FROM NORTHERLY TO SOUTHERLY OVERNIGHT. WINDS
WILL STAY UNDER 12 KT. LOW TO MODERATE CONFIDENCE.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...NONE.
$$
PUBLIC FORECAST: STROBIN
AVIATION/MARINE: CW
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AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
933 PM MDT MON MAR 18 2013
.UPDATE...
&&
.SHORT TERM...CLOUDS AND SNOW ARE LINGERING LONGER THEN EXPECTED
ALONG THE DIVIDE IN ZONES 33 AND 34 SO WILL TEND TO THAT IN THIS
UPDATE. WINDS RELAXING SIGNIFICANTLY OVER THE PLAINS.
.AVIATION...WINDS DECREASING AT DIA AT THIS TIME AND STILL THINK
THEY SHOULD GO TO NEAR NORMAL DRAINAGE DIRECTION SOONER RATHER
THAN LATER. RJK
&&
.PREV DISCUSSION... /ISSUED 343 PM MDT MON MAR 18 2013/
SHORT TERM...WEB CAMS CONTINUE TO SHOW AREAS OF LIGHT SNOW ALONG
THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES...MAINLY WEST
AND NORTH FACING SLOPES. SOME SNOW ALSO OCCURRING OVER THE PARK
AND GORE RANGES OF WESTERN JACKSON COUNTY. THE SNOW HAS BEEN
SHOWING SOME SIGNS OF DECREASING. IN ADDITION...GUSTY WINDS WERE
OCCURRING ALONG THE FOOTHILLS AND ACROSS THE PLAINS WITH SOME
GUSTS AROUND 40 MPH. FOR TONIGHT...STRONG NORTHWEST FLOW ALOFT TO
CONTINUE. MODEL CROSS SECTIONS SHOW DRIER AIR MOVING INTO THE
MOUNTAINS THIS EVENING...SHOULD SEE SNOW CONTINUE TO DECREASE AND
COME TO AN END BY MIDNIGHT. MODELS CONTINUE TO INDICATE THE
DEVELOPMENT OF A STABLE LAYER NEAR MOUNTAIN TOP OVERNIGHT WHICH
WILL HELP WITH THE DEVELOPMENT OF A MOUNTAIN WAVE. THUS...WINDS TO
INCREASE IN AND NEAR FOOTHILLS AFTER MIDNIGHT. LATEST RAP CROSS
SECTIONS SHOWING CROSS MOUNTAIN FLOW INCREASING TO AROUND 50 KTS
AT MOUNTAIN TOP. SOME GUSTS AROUND 60 MPH A POSSIBILITY IN THE
WINDY LOCATIONS. ACROSS PLAINS...WINDS TO DECREASE DURING THE
EVENING ONCE THE AIRMASS STABILIZES. ON TUESDAY...A WEAKER
NORTHWEST FLOW ALOFT WILL BE OVER THE REGION. WINDS SHOULD
DECREASE THOUGH WILL BE A BIT GUSTY AT TIMES ACROSS THE RIDGES AND
ALONG THE FOOTHILLS. MIXING WILL ALSO ALLOW GUSTY WINDS TO OCCUR
NEAR THE WYOMING AND NEBRASKA BORDERS DURING THE AFTERNOON.
AIRMASS TO BE DRIER AND SLIGHTLY WARMER WITH ANY MOISTURE ABOVE
MOUNTAIN TOP. TEMPERATURES SHOULD WARM INTO THE 50S ACROSS THE
PLAINS. SOME AREAS MAY BE SLIGHTLY COOLER DUE TO LESS WIND.
LONG TERM...UPPER LEVEL RIDGE WILL BUILD EASTWARD ACROSS THE
CENTRAL ROCKIES TUESDAY NIGHT AND WEDNESDAY WITH DRY CONDITIONS.
HOWEVER...BY LATE WEDNESDAY...ENOUGH MOISTURE AND INSTABILITY
SHOULD BE ENOUGH TO PRODUCE SHOWERS IN THE MOUNTAINS. THE MAIN
SHOT OF Q-G LIFT AND MOISTURE INCREASE IS STILL SLATED TO HOLD OFF
UNTIL THURSDAY INTO THURSDAY EVENING. AT THIS TIME...THE
COMBINATION OF LIFT AND INSTABILITY SHOULD PRODUCE NUMEROUS
SHOWERS IN THE HIGH COUNTRY WITH LIGHT TO MODERATE SNOW
ACCUMULATIONS. ON THE PLAINS...RAIN SHOWERS ARE EXPECTED TO
DEVELOP BY THURSDAY AFTERNOON AND SPREAD EAST ACROSS THE PLAINS IN
THE EVENING WITH THE BEST LIFT. TEMPERATURES TURN COLD ENOUGH TO
HELP CHANGE RAIN SHOWERS OVER TO SNOW SHOWERS...BUT ANY
ACCUMULATION ON THE PLAINS MAY BE LIMITED OR NIL IF THE COLD AIR
LAGS SLIGHTLY BEHIND THE BETTER PRECIPITION AS CURRENTLY INDICATED
BY MOST MODEL RUNS.
BY FRIDAY INTO SATURDAY...COLD AIR BECOMES MORE FIRMLY ENTRENCHED
ACROSS THE FORECAST AREA. MODELS HAVE SEEM TO COME AROUND TO A
FAIRLY UNIFORM SOLUTION BRINGING ANOTHER UPPER LEVEL DISTURBANCE
AROUND THE BASE OF THE TROUGH FOR FRIDAY NIGHT INTO SATURDAY.
HOWEVER...JUST 24 HOURS AGO WE WERE LOOKING AT A DRY FORECAST FOR
THAT TIME FRAME SO CONFIDENCE ON ANY TIMING HAS TO BE QUITE LOW.
ANOTHER DISTURBANCE IS LIKELY LATE IN THE WEEKEND OR EARLY NEXT
WEEK. THE MAIN POINT OF THIS FORECAST WILL BE TO HAVE AN EXTENDED
PERIOD OF COOLER AND UNSETTLED WEATHER. THERE WILL BE A THREAT OF
ACCUMULATING SNOWFALL WITH ANY OF THE DISTURBANCES THAT MOVE
THROUGH.
AVIATION...WINDS HAVE BEEN MORE WESTERLY AT KDEN AND KBJC WITH
NORTHWESTERLY AT KAPA. LATEST RAP AND HRRR CONTINUE TO INDICATE
NORTHWEST WINDS ACROSS THE AREA AIRPORTS THROUGH 01Z...STILL
EXPECTING WINDS TO BECOME A BIT MORE NORTHWEST AS MIXING
CONTINUES WITH SOME GUSTS AROUND 35 KTS. WINDS TO WEAKEN AFTER 01Z
AND BECOMING SOUTHERLY BY 03Z AS DRAINAGE PATTERN DEVELOPS. WINDS
TO BE MORE WESTERLY AT BJC DUE TO THE LOCAL DOWNSLOPE WITH
OCCASIONAL GUSTS TO 30 KTS POSSIBLE. ON TUESDAY...WINDS TO SHIFT
TO THE NORTHWEST BY 15Z WITH SPEEDS LESS THAN 10 KTS. WINDS COULD
BECOME NORTHEAST OR EAST AT DEN DURING THE AFTERNOON AS MODELS
SHOW WEAK SURFACE HIGH DEVELOPING IN THE DENVER AREA. VFR TO
CONTINUE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....D-L
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
259 PM MDT SUN MAR 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 258 PM MDT SUN MAR 17 2013
...STRONG WINDS AND HIGH FIRE DANGER THE MAIN CONCERN FOR THE I-25
CORRIDOR AND ADJACENT PLAINS...
UPPER TROF CURRENTLY MOVING ACROSS THE AREA WITH NICE DRYING ON THE
BACK SIDE MOVING ACROSS THE SOUTHEAST MOUNTAINS. SOUTHWEST WINDS
HAVE BEGUN TO INCREASE ALONG THE I-25 CORRIDOR...WITH THE SOUTHERN
I-25 CORRIDOR SEEING THE STRONGEST GUSTS THUS FAR...WITH I-25 AT
BUTTE CREEK PICKING UP A GUST TO AROUND 54 MPH SHORTLY AFTER 18Z.
THIS WAS ABOUT THE TIME A WAVE OF THUNDERSTORMS MOVED OFF THE
MOUNTAINS IN THAT AREA. THESE THUNDERSTORMS HAVE SINCE PUSHED OFF
INTO THE FAR SOUTHEAST PLAINS...AND WEATHER SPOTTERS IN THE AREA
HAVE REPORTED SOME BRIEF PEA SIZE HAIL WITH THE STRONGER CELLS. SO
FAR...WIND GUSTS HAVE STAYED UNDER 50 MPH. THIS MAY BE DUE TO THE
FACT THAT SURFACE DEW POINTS ARE STILL FAIRLY HIGH...EVEN BEHIND THE
SFC TROF AXIS...AND WITH LESS OF A T/TD SPREAD...ACCELERATION FROM
DOWNDRAFTS HASN/T BEEN STRONG ENOUGH TO GOOSE WIND SPEEDS ABOVE HIGH
WIND CRITERIA. WILL CONTINUE TO MONITOR THOUGH AS THESE CELLS
CONTINUE TO PROGRESS EASTWARD THROUGH THE AFTERNOON.
MEANWHILE...SFC DEW POINTS HAVE BEGUN TO DROP OFF INTO THE TEENS
ALONG THE I-25 CORRIDOR...AND TEMPERATURES HAVE WARMED INTO THE
LOWER TO MID 60S ACROSS THE SOUTHERN I-25 CORRIDOR. STILL WAITING
FOR THE HUMIDITIES TO DROP BELOW 15 PERCENT...THOUGH FCS AND RED
CREEK RAWS ARE AT 16% AS OF 2 PM. LOCAL 4KM WRF STILL SHOWS DEW
POINTS DROPPING INTO THE LOWER TEENS ALONG THE I-25 CORRIDOR BY
22Z...AND SPREADING EASTWARD INTO THE FAR EASTERN COUNTIES BY 00Z.
SINCE LINE OF CONVECTION THUS FAR WASN/T ENOUGH TO GOOSE UP WINDS
ABOVE HIGH WIND CRITERIA...ONE WINDOW HAS CLOSED. HOWEVER...ANOTHER
SHOT FOR SOME SPOTTY HIGH WIND CRITERIA OPENS AGAIN AROUND 00Z AS
STRONGER WINDS ALOFT BEHIND THE FRONT SPREAD INTO THE I-25
CORRIDOR. BOTH WRF...AND HRRR SHOW WIND GUSTS UP TO 40-45 KTS.
LOCAL 4KM WRF HAS TRENDED DOWN WITH THESE GUSTS THOUGH AS COMPARED
TO THE EARLIER 00Z RUN. SO ALTHOUGH I CAN/T ENTIRELY RULE OUT A
SPOTTY HIGH WIND CRITERIA GUST ALONG THE I-25 CORRIDOR THROUGH EARLY
EVENING...IF IT DOES OCCUR...THINK IT WILL BE TOO SPOTTY/BRIEF TO WARRANT
ANY HIGH WIND HIGHLIGHTS. NAM12 MODELS HINT AT A WEAK MTN TOP
STABLE LAYER DEVELOPING BY 03Z...BUT 18Z NAM HAS DONE AWAY WITH THIS
FEATURE. BY 06Z...WINDS QUICKLY ATTAIN QUITE A BIT OF FORWARD
SHEAR...WHICH SHOULD CUT OFF ANY MTN WAVE POTENTIAL. BOTTOM
LINE...PARAMETERS APPEAR TO NOT BE IN PLACE LONG ENOUGH TO JUSTIFY A
HIGH WIND WARNING AT THIS POINT. WITHOUT A CRITICAL LAYER IN
PLACE...A WAVE INDUCED ONE WOULD HAVE TO OCCUR TO BRING STRONG WINDS
DOWN...AND THIS SEEMS LESS AND LESS LIKELY...THOUGH NOT ENTIRELY
IMPOSSIBLE.
MEANWHILE...OROGRAPHIC SNOW SHOWERS WILL CONTINUE ALONG THE
CONTINENTAL DIVIDE...THOUGH SHOULD BE DECREASING RAPIDLY IN COVERAGE
OVERNIGHT. ANOTHER 1 TO 2 INCHES WILL BE POSSIBLE OVERNIGHT WITH
SOME POOR VISIBILITIES AT TIMES IN WIND DRIVEN SNOW. HAVE BEEN
MONITORING WEB CAMS...AND SO FAR VISIBILITY HASN/T BEEN IMPACTED
THAT MUCH TO WARRANT AN ADVISORY. IN FACT...CDOT WEB CAMS OVER WOLF
CREEK AND FREMONT PASSES SHOW THE ROADS HAVE MELTED OUT IN THE PAST
COUPLE HOURS. MOST HAZARDOUS CONDITIONS WILL LIKELY CONTINUE ACROSS
MONARCH PASS WHERE ROAD SFC WILL STAY SNOW COVERED.
FOR TOMORROW...WINDS WILL INCREASE AGAIN ALONG THE I-25 CORRIDOR AND
WITH DEEP DRY AIR OVER THE REGION...SFC DEW POINTS WILL FALL INTO
THE SINGLE DIGITS AND EVEN BELOW ZERO. ALTHOUGH WINDS ARE NOT
EXPECTED TO BE A STRONG AS THEY WERE TODAY...WE COULD BE LOOKING AT
BRIEF CRITICAL FIRE WEATHER CONDITIONS ACROSS
PUEBLO...CROWLEY...OTERO...AND PERHAPS PORTIONS OF LAS ANIMAS COUNTIES
IN THE AFTERNOON. FOR NOW...NOT GETTING A LONG ENOUGH DURATION (3
HRS OR MORE) OF HUMIDITY BELOW 15 PERCENT...SO WILL HOLD OFF ON ANY
FIRE WEATHER HIGHLIGHTS. BUT THIS MAY NEED TO BE REVISITED WITH
FUTURE MODEL RUNS. TEMPERATURES SHOULD BE A LITTLE COOLER
TOMORROW...BUT WITH THE WIND THEY SHOULD STILL WARM INTO THE 50S
ACROSS THE PLAINS...WITH 30S AND 40S ACROSS THE HIGH COUNTRY. -KT
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 258 PM MDT SUN MAR 17 2013
...COOLER AND MORE UNSETTLED WEATHER FOR MID WEEK AND BEYOND...
MONDAY NIGHT-TUESDAY NIGHT...MODERATING WESTERLY FLOW PROGGED
ACROSS THE REGION WITH FLAT RIDGING BUILDING ACROSS THE GREAT BASIN
AND INTO THE ROCKIES. WILL CONTINUE TO SEE SOME LIGHT SNOW SHOWERS
ACROSS THE CENTRAL MTS MONDAY EVENING WITH SHOWERS ENDING THROUGH
THE LATE EVENING AND OVERNIGHT HOURS WITH DEVELOPING WAA. WITH THE
DECREASING FLOW ALOFT AND DECOUPLED WINDS ACROSS THE PLAINS...HAVE
LOWERED OVERNIGHT LOWS A TAD...ESPECIALLY ACROSS VALLEY LOCALES.
SOME MODEL DIFFERENCES CONTINUE TO BE INDICATED FOR TUESDAY
AFTERNOON AND EVENING AS THE LATEST ECMWF CONTINUES TO INDICATE
STRONGER SOUTHERN STREAM ENERGY TRANSLATING ACROSS THE DESERT SW
AND NORTHERN NEW MEXICO AND PRINTS OUT SOME LIGHT QFP ACROSS THE
SOUTHERN MTS TUESDAY AFTERNOON AND EVENING. THE GFS IS A LITTLE
FURTHER SOUTH WITH THIS SYSTEM AND ITS ASSOCIATED QPF. AT ANY
RATE...HAVE FOLLOWED CLOSER TO THE GFS SOLUTION WITH LATEST WPC
(FORMERLY HPC) GUIDANCE TRENDING AWAY FROM A DISTINCT SOUTHERN
STREAM SHORTWAVE AT THIS TIME...AND HAVE STARTED TO TRIM BACK THE
SLIGHT POPS ACROSS THE HIGHER TERRAIN OF THE CONTDVD FOR TUESDAY
AFTERNOON AND EVENING. AS FOR TEMPERATURES...WITH WEAK UPSLOPE FLOW
PROGGED ACROSS THE EASTERN PLAINS...HAVE TRIMMED BACK HIGHS A TAD AS
WELL THOUGH SHOULD STILL BE NEAR SEASONAL AVERAGES.
WEDNESDAY-FRIDAY...COOLER AND MORE UNSETTLED WEATHER REMAINS IN THE
OFFING...THOUGH MODELS HAVE TRENDED SLOWER AND FURTHER NORTH WITH
THE BROAD UPPER TROUGH CARVING OUT ACROSS THE WEST COAST ON
WEDNESDAY WHICH THEN CONTINUES TO TRANSLATE OUT ACROSS THE NORTHERN
GREAT BASIN AND THE NORTHERN ROCKIES THROUGH FRIDAY. THIS FURTHER
NORTH TREND WOULD KEEP THE BULK OF THE PRECIPITATION ACROSS THE
CENTRAL MTS THROUGH NORTHEASTERN COLORADO AND NORTHWESTERN KANSAS
WITH MORE DOWNSLOPE FLOW IN PLACE ACROSS SOUTHEAST COLORADO. AT ANY
RATE...MOISTURE INCREASES ACROSS THE CONTDVD WEDNESDAY WITH SHOWERS
DEVELOPING THROUGH MORNING AND INCREASING IN COVERAGE AND SPREADING
EAST THROUGH THE AFTERNOON AND EVENING. SHOWERS TO CONTINUE ACROSS
THE HIGHER TERRAIN WEDNESDAY NIGHT AND THURSDAY AS BROAD TROUGH
CONTINUES TO MOVE EAST...AND MAY NEED SOME HIGHLIGHTS THROUGH THIS
PERIOD...MAINLY FOR THE CENTRAL MTS. BEST CHANCES OF RAIN AND SNOW
SHOWERS ACROSS THE EASTERN COLORADO LOOKS TO BE THURSDAY AFTERNOON
AND NIGHT AS AN ASSOCIATED COLD FRONT BACKS ACROSS THE PLAINS.
SHOWERS TO PERSIST ACROSS MAINLY THE HIGHER TERRAIN ON FRIDAY WITH
COOL NORTHWEST FLOW AND POSSIBLE TRAILING ENERGY TRANSLATING ACROSS
THE GREAT BASIN. HIGHS ON FRIDAY LOOK TO BE WELL BELOW SEASONAL
LEVELS WITH THE COLD AIRMASS IN PLACE.
SATURDAY-SUNDAY...LOW CONFIDENCE FORECAST CONTINUES INTO THE WEEKEND
AS THE LATEST EC CONTINUES TO INDICATE COOL NORTHWEST FLOW WITH
SEVERAL EMBEDDED SHORTWAVES TRANSLATING THROUGH THE FLOW...WHERE AS
THE GFS HAS SHORT WAVE RIDGING BUILDING ACROSS THE GREAT BASIN AND
INTO THE ROCKIES. WITH THAT SAID...HAVE STAYED WITH MODEL CONSENSUS
WHICH KEEPS ISOLATED POPS ACROSS THE HIGHER TERRAIN ALONG WITH A
SLOW WARMUP TO SEASONAL TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 258 PM MDT SUN MAR 17 2013
GUSTY WINDS THE MAIN CONCERN IN TAF SITES...WITH WEST TO NORTHWEST
WINDS PICKING UP AND GUSTING TO AROUND 40 KTS AT KCOS AND KPUB
DURING THE LATE AFTERNOON AND EARLY EVENING. KALS COULD SEE GUSTS
TO AROUND 30 KTS. WINDOW FOR VCSH HAS PRIMARILY ENDED FOR THE TAF
SITES...THOUGH THE CENTRAL AND SOUTHWEST MOUNTAINS COULD STILL SEE
SOME MTN OBSCURATIONS THROUGH TONIGHT...ESPECIALLY ACROSS THE
SAWATCH AND MOSQUITO RANGES WHERE OROGRAPHIC SNOW SHOWERS WILL
CONTINUE. WINDS WILL DECREASE AFTER 02Z...THOUGH STILL REMAIN GUSTY
AT TIMES FROM THE NORTHWEST AT 10-25 KTS FOR KCOS AND KPUB. ON
MONDAY...WINDS WILL INCREASE AGAIN AFTER 18Z TO AROUND 15-25 KTS FOR
KCOS AND KPUB. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ227-228-
231>233.
&&
$$
SHORT TERM...KT
LONG TERM...MW
AVIATION...KT
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
823 PM EDT MON MAR 18 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE AREA FROM THE NORTHWEST EARLY
TUESDAY...FOLLOWED BY BRIEF HIGH PRESSURE THROUGH WEDNESDAY...WITH
ANOTHER COLD FRONTAL PASSAGE WEDNESDAY NIGHT. RAIN CHANCES WILL
INCREASE LATE IN THE WEEK AS A COUPLE LOW PRESSURE SYSTEMS MOVE
OVER OR JUST SOUTH OF THE AREA.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
THIS EVENING...THE APPROACHING UPSTREAM LINE OF CONVECTION HAS
DEVELOPED NICELY SINCE THIS AFTERNOON AND IS SURGING TO THE
SOUTHEAST. BASED ON THE MATURITY OF THE LINE...ITS HISTORY OF
PRODUCING LARGE HAIL AND DAMAGING WINDS...AND ITS BRISK FORWARD
PACE SPC HAS ISSUED SEVERE THUNDERSTORM WATCH 55 WHICH GOES
THROUGH 06Z FOR ALL OF SOUTHEAST GA AND THE SOUTHEAST SC COUNTIES
ALONG THE SAVANNAH RIVER.
ALTHOUGH THIS LINE IS GOING TO BE AFFECTING THE AREA AT A
CLIMATOLOGICALLY UNFAVORABLE TIME OF DAY FOR SEVERE WEATHER...ITS
CURRENT STATE AND INTENSITY WILL ALLOW IT TO MAINTAIN INTO THE
FORECAST AREA THROUGH LATE THIS EVENING. CURRENTLY THERE ARE
DISCRETE CELLS DEVELOPING OUT AHEAD OF THE LINE...BUT WITH THE
LOSS OF HEATING AND OVERALL LACK OF SURFACE BASED INSTABILITY THE
PRIMARY MODE OF CONVECTION WILL BE LINEAR. SOUNDINGS AND VARIOUS
PLAN VIEW MESOSCALE ANALYSES SHOW AN EXCELLENT MID LEVEL
ENVIRONMENT MARKED BY STEEP LAPSE RATES AND LIFTED INDICES AS LOW
AS -3. DEEP LAYER SHEAR IS ON THE ORDER OF 50-60 KTS BASED ON LAPS
ANALYSIS WITH A TONGUE OF CAPE VALUES UPWARDS OF 800 J/KG ACROSS
THE WATCH AREA. LARGE HAIL AND DAMAGING WINDS ARE THE PRIMARY
THREAT AND A BRIEF TORNADO CANNOT BE TOTALLY RULED OUT BASED ON
THE DEGREE OF AMBIENT SHEAR. WITH THE LINE MOVING AS FAST AS IT
IS...IT WILL PROGRESS QUICKLY THROUGH THE FORECAST AREA. I HAVE
FOLLOWED THE HRRR FOR TIMING OF THE LINE AS IT SEEMS TO BE
INITIALIZING THE BEST. THE LINE WILL BEGIN AFFECTING
JENKINS/CANDLER COUNTIES IN THE 01-02Z TIME FRAME AND IS EXPECTED
TO BE INTO THE COASTAL WATERS BY 05-06Z.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
THE COLD FRONT SHOULD BE MOVING OFF THE COAST FAIRLY EARLY IN THE
MORNING IN RESPONSE TO AN UPPER LEVEL DISTURBANCE MOVING INTO THE
NORTHEAST AND MID ATLANTIC STATES. ANY LINGERING SHOWERS AND
THUNDERSTORMS SHOULD SHIFT OFF THE COAST BY MID TO LATE MORNING. THE
COLD ADVECTION LAGS SOME BEHIND THE FRONT...SO WITH CLEARING SKIES
AND DOWNSLOPE FLOW...TUESDAY AFTERNOON LOOKS TO BE QUITE WARM.
PUSHED HIGH TEMPERATURES INTO THE MID AND UPPER 70S IN MOST
LOCATIONS AWAY FROM THE COAST. IT WILL BE A LITTLE BREEZY BEHIND THE
FRONT ON TUESDAY...WITH SOME GUSTS UP TO AROUND 20 MPH.
THE SURFACE HIGH PRESSURE WILL QUICKLY BUILD INTO THE SOUTHEASTERN
STATES TUESDAY NIGHT. EVEN THOUGH SKIES WILL BE CLEAR AND DEWPOINTS
WILL BE FALLING INTO THE 30S IN MOST LOCALS...THINK THERE WILL BE
ENOUGH WIND IN MOST PLACES TO KEEP FROM DECOUPLING. AS A
RESULT...BELIEVE THAT MIN TEMPERATURES WILL BE IN THE 40S IN MOST
LOCALS.
THERE IS INCREASING UNCERTAINTY IN THE FORECAST FOR WEDNESDAY...
MAINLY AS A RESULT OF THE 12Z NAM SOLUTION WHICH BRINGS A COLD RAIN
TO MAINLY COASTAL COUNTIES. GFS KEEPS RAIN OFF THE COAST AND IS NO
WHERE NEAR AS IMPRESSIVE WITH ISENTROPIC LIFT AS NAM. CANADIAN AND
ECMWF ARE EVEN LESS IMPRESSIVE WITH THE ISENTROPIC LIFT AND MORE
QUICKLY MOVE ANY LIFT EAST OF THE AREA. TRENDED A LITTLE LOWER FOR
HIGH TEMPERATURES AND INCREASED CLOUD COVER ON WEDNESDAY AS A RESULT
OF NAM SOLUTION. WOULD LIKE TO SEE THE NAM MAINTAIN THIS TREND AND
OTHER MODELS TO JUMP ON BOARD BEFORE MAKING ANY MORE SIGNIFICANT
CHANGES. IF THE NAM IS CORRECT...MOST AREAS THAT SEE RAIN WILL
LIKELY REMAIN IN THE 40S ON WEDNESDAY. FOR NOW MAINLY CARRIED HIGHS
IN THE MID TO UPPER 60S.
LIKE FOR THE WEDNESDAY FORECAST...GENERALLY FOLLOWED
GFS/ECMWF/CANADIAN SOLUTION FOR WEDNESDAY NIGHT AND THURSDAY. COOLER
AND DRIER AIR WILL ADVECT INTO THE AREA...WITH HIGHS ON THURSDAY
MAINLY IN THE LOWER TO MID 60S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
CONFIDENCE IS LOW IN THE EXACT DETAILS THIS PERIOD AS THERE ARE
STILL MODEL DISCREPANCIES REGARDING THE LATE WEEK/WEEKEND PERIOD.
HOWEVER...CONFIDENCE IS HIGH THAT A COUPLE WAVES OF LOW PRESSURE
WILL MOVE OVER OR JUST SOUTH OF THE AREA THROUGH THE WEEKEND LEADING
TO HIGH RAIN CHANCES AND BELOW NORMAL TEMPERATURES. RAINFALL TOTALS
THROUGH THE PERIOD COULD REACH ONE OR TWO INCHES...ESPECIALLY ACROSS
SOUTHEAST GEORGIA.
TEMPERATURES WILL BE RATHER TRICKY BUT LOOK TO REMAIN BELOW NORMAL
THROUGH THE PERIOD. IT IS CERTAINLY POSSIBLE THAT SOME AREAS...
ESPECIALLY INTERIOR PORTIONS OF SOUTHEAST SC/GA...DO NOT GET OUT
OF THE 50S THURSDAY THROUGH SUNDAY. ALSO...THERE IS A SMALL CHANCE
THAT CONDITIONS COULD BE FAVORABLE FOR SOME FROST FRIDAY MORNING
ACROSS INLAND AREAS DEPENDING ON HOW QUICKLY THE RAIN MOVES IN.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
CURRENT RADAR AT 00Z SHOWS A LINE OF CONVECTION ACROSS CENTRAL GA.
LATEST HIGH RES GUIDANCE SHOWS THAT THIS LINE WILL MAKE IT TO THE
COAST...WITH TIMING OF ARRIVAL IN THE KSAV VICINITY AROUND 03Z.
BEST POTENTIAL FOR THUNDER LOOKS TO BE AT KSAV...SO HAVE NO
MENTION IN KCHS TAF AT THIS TIME. LOWER VSBYS/FLIGHT RESTRICTIONS
ARE POSSIBLE WITHIN HEAVIEST RAINFALL...AND HAVE INCLUDED A TEMPO
GROUP AT KSAV TO ACCOUNT FOR THIS AND POTENTIAL STRONG GUSTS WITH
THIS LINE. ONCE THE LINE MOVES THROUGH MODEL GUIDANCE HINTS THE
DEVELOPMENT OF IFR CIGS THROUGH DAYBREAK. HAVE KEPT MVFR FOR NOW
BUT WILL MONITOR TRENDS AND AMEND AS NECESSARY.
EXTENDED AVIATION OUTLOOK...
VFR CONDITIONS WILL GENERALLY PREVAIL. LOW END PROBABILITIES OF
LOWER CIGS/VSBYS FOR WEDNESDAY ALONG WITH BREEZY CONDITIONS.
&&
.MARINE...
IN AN EXPANDING WARM SECTOR AHEAD OF A COLD FRONT APPROACHING FROM
THE NW A TIGHTENING SURFACE PRESSURE GRADIENT AND STRENGTHENING LOW
LEVEL WINDS WILL SUPPORT INCREASING S/SW WINDS ACROSS THE COASTAL
WATERS...ALTHOUGH COOL SHELF WATERS WILL DETER A SIGNIFICANT MIXING
ENVIRONMENT. WE THINK VERY MARGINAL SMALL CRAFT ADVISORY CONDITIONS
ARE POSSIBLE OVER OUR OUTER GEORGIA WATERS CLOSER TO THE GULF STREAM
AS THE LOW LEVEL JET STRENGTHENS. WE HAVE MAINTAINED AN ADVISORY
OVER AMZ374 BEGINNING LATER THIS EVENING.
OTHERWISE...LOW LEVEL FLOW WILL VEER TO SW OVERNIGHT WITH SEAS
BUILDING TO 3 TO 4 FT NEAR SHORE TONIGHT AND UP TO 5 FT WELL OFF
THE GEORGIA COAST.
TUESDAY THROUGH SATURDAY...A COLD FRONT WILL MOVE THROUGH THE WATERS
TUESDAY MORNING WITH HIGH PRESSURE BUILDING FROM THE NORTHWEST
TUESDAY NIGHT. THE HIGH WILL WEAKEN WEDNESDAY AS ANOTHER COLD FRONT
APPROACHES AND EVENTUALLY PUSHES OFFSHORE WEDNESDAY NIGHT. HIGH
PRESSURE WILL THEN BUILD BACK IN THURSDAY WITH AT LEAST ONE AREA OF
LOW PRESSURE TO TRACK OVER OR JUST SOUTH OF THE WATERS THROUGH LATE
WEEK.
THIS PATTERN WILL YIELD SEVERAL BOUTS OF INCREASED WINDS AND SEAS
BUT OVERALL THE CHANCES OF ADVISORY CONDITIONS APPEAR LOW AT THIS
TIME...AT LEAST THROUGH FRIDAY. THE BEST CHANCE OF AN SCA WILL
LIKELY BE IN CHARLESTON HARBOR TUE AND/OR WED AFTERNOON DUE TO
BREEZY CONDITIONS ALONG THE LAND/SEA INTERFACE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT TUESDAY FOR AMZ374.
&&
$$
NEAR TERM...BSH
SHORT TERM...MTE
LONG TERM...MTE
AVIATION...ECT/BSH
MARINE...MTE
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
259 AM EDT SUN MAR 17 2013
.PREV DISCUSSION... /ISSUED 945 PM EDT SAT MAR 16 2013/
UPDATE...
HAVE MADE SEVERAL MINOR TWEAKS TO THE FORECAST...MAINLY TO SKY
COVER AS PART OF THE 00Z TAF ISSUANCE. BOTH HRRR AND LOCAL WRF
KEEP ALL RAIN NORTH OF THE AREA TONIGHT SO REMOVED POPS FROM
EXTREME NORTH GEORGIA AND ADDED A LITTLE FOG WORDING IN AS
WELL...WITH LOW CLOUDS MOVING IN SUNDAY MORNING EXPECT SOME PATCHY
FOG TO DEVELOP. NO MAJOR CHANGE TO TEMPS EXCEPT FOR MINOR TWEAKS
TO UPDATE FOR TRENDS. UPDATED PRODUCTS WILL BE OUT SHORTLY.
TDP
PREV DISCUSSION... /ISSUED 833 PM EDT SAT MAR 16 2013/
PREV DISCUSSION... /ISSUED 340 PM EDT SAT MAR 16 2013/
SHORT TERM /TONIGHT THROUGH SUNDAY/...
CURRENT SATELLITE LOOP SHOWS MOSTLY CLEAR SKIES ACROSS NORTH AND
CENTRAL GEORGIA. SURFACE HIGH PRESSURE WILL CONTINUE TO PERSIST
THROUGH THE WEEKEND...WITH WARMING ABOVE NORMAL TEMPERATURES
CONTINUING TODAY AND SUNDAY. EXPECT HIGH TEMPERATURES IN THE LOW TO
MID 70S...AND LOWS IN THE UPPER 40S AND LOW 50S. THE MODELS ARE IN
DECENT AGREEMENT AND FAIRLY CONSISTENT WITH WEAK FRONTAL BOUNDARY
SAGGING INTO THE TENNESSEE VALLEY TODAY. THIS FRONTAL BOUNDARY
SHOULD INCREASE CLOUD COVER ESPECIALLY ACROSS NORTH GA SUN AND MAY
EVEN SEE SOME ISOLATED SHOWERS SUN AFTERNOON ALSO. THE MODELS ARE
ALSO SHOWING A WEAK DISTURBANCE MOVING NORTHWARD INTO THE REGION
FROM THE GULF OF MEXICO WHICH WILL BRING ADDITIONAL MOISTURE INTO THE
AREA SUNDAY AFTERNOON INTO SUN NIGHT FOR NOW...HAVE INDICATED INCREASED
CLOUD COVER ACROSS CENTRAL GEORGIA AS A RESULT...AND ANY RESULTING
RAINFALL SHOULD STAY SOUTH OF THE CWA.
01
LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
WARM FRONT/STALLED FRONTAL BOUNDARY REMAINS ACROSS THE GA/TN BORDER
ON SUNDAY NIGHT. BOTH THE NAM AND GFS ARE PICKING UP ON A SHORTWAVE
MOVING NORTH IN THE SW FLOW FROM THE GULF OF MEXICO SUNDAY NIGHT.
BOTH MODELS PRODUCE PRECIP WITH THIS FEATURE...BUT THE NAM IS
FURTHER SOUTH WITH ITS BULLSEYE. WILL END UP ADDING SOME LOW END
CHANCE POPS FOR SHOWERS IN THE SW PORTION OF THE CWFA SUNDAY
EVENING.
A COLD FRONT IS STILL PROGGED TO MOVE THROUGH THE CWFA ON MONDAY
INTO EARLY TUESDAY. THE MAIN MID LEVEL FORCING WITH THIS SYSTEM
REMAINS WELL TO THE NORTH...BUT THERE WILL BE SOME LIFT/FORCING
ALONG THE FRONT. SURFACE INSTABILITY WILL SPREAD AHEAD OF THE FRONT
MONDAY AFTERNOON AND EVENING...ALONG WITH SOME DECENT SHEAR.
ISOLD/SCT SEVERE STORMS ARE POSSIBLE. BOTH THE NAM AND GFS ARE ALSO
SETTING UP A COOL AIR WEDGE ACROSS THE NE CWFA SUNDAY NIGHT INTO
MONDAY. AREAS IN THE WEDGE WILL STAY MORE STABLE. HOWEVER...ALONG
THE WEDGE FRONT...LOCALIZED HIGH SRH MAY BE ENHANCED.
THE COLD FRONT MAY HANG UP ACROSS THE SOUTHERN CWFA...BUT SHOULD
CLEAR THE AREA BY EARLY TUESDAY MORNING. HAVE TRIED TO ARRANGE POPS
ACCORDINGLY.
MID LEVEL FLOW REMAINS ZONAL FOR THE REMAINDER OF THE LONG TERM
PERIOD. SEVERAL FAST MOVING PIECES OF S/W ENERGY ARE PROGGED TO MOVE
THROUGH THE ATMOS...EACH TRIGGERING CLOUDS/SMALL POPS.
NLISTEMAA
&&
.AVIATION...
06Z UPDATE...
VFR CONDITIONS EXPECTED THROUGH 11-12Z THIS MORNING WHEN
ADDITIONAL MOISTURE IN THE AREA WILL RESULT IN BKN MVFR CIGS.
CONFIDENCE IN THESE CIG HEIGHTS IS LOW-MEDIUM AS LATEST MODELS
HAVE TRENDED TOWARDS KEEPING CIGS...IF ANY...TO LOW VFR. ANY CIGS
THAT DO DEVELOP ARE EXPECTED TO LIFT BY LATE MORNING. CIGS WILL
ONCE AGAIN DROP SUNDAY NIGHT...WITH MVFR EXPECTED. WINDS WILL BE
SW WINDS AT 7-10KT EXPECTED TODAY...WITH SHIFT TO THE SOUTH AND
POSSIBLY SSE AT 4-6KT AFTER 02-03Z MONDAY.
//ATL CONFIDENCE...06Z UPDATE...
LOW TO MEDIUM CONFIDENCE ON CIGS 12-15Z.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 77 55 72 49 / 20 30 50 60
ATLANTA 73 58 71 49 / 20 30 60 60
BLAIRSVILLE 70 51 62 44 / 20 30 70 60
CARTERSVILLE 74 55 71 48 / 20 30 70 60
COLUMBUS 76 59 75 54 / 10 30 50 60
GAINESVILLE 73 55 66 48 / 20 30 60 60
MACON 76 55 74 53 / 10 30 50 60
ROME 74 56 71 48 / 20 40 70 50
PEACHTREE CITY 74 54 72 50 / 10 30 60 60
VIDALIA 78 55 78 58 / 10 20 40 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....ARG
AVIATION...31
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1039 PM CDT MON MAR 18 2013
.DISCUSSION...
1037 PM CDT
UPDATE FOR OVERNIGHT...
STRONG COLD AIR ADVECTION THAT STARTED THIS AFTERNOON AND
CONTINUED THROUGH THE EVENING WILL PERSIST OVERNIGHT.
BLUSTERY CONDITIONS WILL ALSO CONTINUE AS UNIDIRECTIONAL W WIND
IS MAINTAINED WITH SPEEDS OF 35 TO 40 KT UP TO BASE OF INVERSION
AT 3-4K FT.
STRONG MID LEVEL TROUGH HAS ROTATED N TO THE NORTHERN GREAT LAKES
THIS EVENING TAKING THE SIGNIFICANT SNOW AND SNOW SHOWERS WITH
IT. A SECOND BROADER MID LEVEL TROUGH IS CURRENTLY ROTATING E
OVER WI AND IL WITH A SOME FLURRIES AND A FEW SNOW SHOWERS. IN
THE WAKE OF THIS TROUGH SKIES HAVE BECOME PARTLY CLOUDY/MOSTLY
CLEAR ACROSS THE NW 1/3RD OF THE LOCAL FORECAST AREA AS
SUBSIDENCE IN THE LOWER LEVELS INCREASES. EXPECT THIS TREND TO
CONTINUE OVERNIGHT AS THE MID LEVEL TROUGH ROTATES NE PAST THE
AREA THOUGH WHEN THIS COLD JUST ABOUT ANY PATCH OF STRATOCU CAN
PRODUCE SOME FLURRIES.
AREAS OF MAINLY LIGHT SNOW ARE OVER PORTIONS OF MN AND WI UNDER
THE UPPER TROUGH THAT IS CLOSING OFF TO AN UPPER LOW. WITH THIS
UPPER LOW TO MOVE SLOWLY E OVERNIGHT THE ASSOCIATED CLOUDS AND
SNOW SHOWERS/FLURRIES ARE EXPECTED TO BE N OF THE WI STATE LINE.
TRS
&&
.PREV DISCUSSION...
345 PM CDT
WHILE THE TRUE VERNAL EQUINOX ARRIVES WEDNESDAY...AND WE ARE THREE
WEEKS INTO METEOROLOGICAL WINTER...THE MAIN WEATHER HEADLINE THIS
WEEK WILL BE HOW UNSPRING-LIKE THE TEMPERATURES WILL BE. THIS
PRESENTS THE MAIN FORECAST CHALLENGE...ALONG WITH ANY SMALL
CHANCES FOR SNOW SHOWERS.
SYNOPSIS AND LATE THIS AFTERNOON...THE POTENT UPPER LEVEL LOW IS
MOVING EAST ACROSS MN THIS AFTERNOON...WITH THE MID-LEVEL JET AND
A VORT LOBE OF THE SYSTEM RUSHING EASTWARD OVER NORTHERN IL.
ENHANCEMENT ON THE LEADING EDGE OF THESE STEEPER MID-LEVEL LAPSE
RATES AND CONVERGENCE IS SEEN IN SNOW SHOWERS TRAVERSING NORTHEAST
ILLINOIS AS OF 3 PM. SPOTTIER HEAVIER SNOWFALL RATES WILL BE SEEN
IN THIS ACTIVITY AS IT DEPARTS. THE SURFACE ARCTIC FRONT OF THIS
SYSTEM IS CROSSING THE MISSISSIPPI RIVER AND WILL MOVE THROUGH THE
ENTIRE CWA BETWEEN 5 AND 9 PM. THIS WILL TURN THE SYNOPTIC PATTERN
TO ONE OF NORTHWEST FLOW AND COLD WHICH WILL CONTINUE TO REINFORCE
ITSELF THROUGH THE WEEK AS THE UPPER AND SURFACE LOWS EXPAND AND
SLOW ACROSS THE CENTRAL AND EASTERN GREAT LAKES. NUMEROUS SHORT
WAVE IMPULSES ARE EXPECTED TO RIDE AROUND THIS FEATURE WITH
MINIMAL CAUSES FOR SNOW...BUT EACH DRIVING COLD SURGES BACK INTO
THE AREA.
TONIGHT...SHORT TERM GUIDANCE IS IN GOOD AGREEMENT ON THE TIMING
OF THE ARCTIC FRONT THIS EVENING...ALONG WITH AGREEING THAT THE
STEEPENING OF THE LOW-LEVEL LAPSE RATES WILL LIKELY PRODUCE
SURFACE-BASED INSTABILITY. FORECAST SOUNDINGS FROM THE RAP YIELD
AROUND 50 J/KG OF MLCAPE ALONG AND IMMEDIATELY BEHIND THE FRONT.
THE SATURATED DEPTH AT THE TOP OF THIS MIXED LAYER IS QUITE
SHALLOW BUT MOST CONVECTIVE-ALLOWING ARW AND WRF GUIDANCE DO
CONTINUE TO PRODUCE A SPATTERING OF HIGHER REFLECTIVITY INDICATIVE
OF SNOW SHOWERS. WILL CARRY FLURRIES WITH A MENTION OF ISOLATED TO
SCATTERED SNOW SHOWERS.
THE FRONT WILL BRING BOTH STRONG HEIGHT AND PRESSURE RISES WHICH
ARE LINED UP WELL WITH A UNIDIRECTIONAL WIND COLUMN IN THE LOW-
LEVELS. THE TOP OF THE MIXED LAYER ON THE LATEST RAP GUIDANCE AS
WELL AS LOCAL ARW DOES YIELD 40 MPH GUSTS THIS EVENING. HAVE
INCLUDED SUCH GUSTS IMMEDIATELY BEHIND THE FRONT AND WOULD NOT BE
SURPRISED IF SOME PLACES IN THE SOUTHWEST FORECAST AREA COME IN A
BIT HIGHER. IF SNOW SHOWERS DO DEVELOP...SOME NOTABLE REDUCTIONS
IN VISIBILITY MAY BE SEEN DUE TO THE COMBINATION OF WINDS AND
SNOWFALL. WITH TEMPERATURES FALLING QUICKLY...WIND CHILLS IN THE
NORTHWEST FORECAST AREA LOOK TO ALREADY BE IN THE SINGLE DIGITS
BY 9 PM THIS EVENING. THIS DEGREE OF COLD AIR WILL SWEEP OVER THE
ENTIRE FORECAST AREA WITH EARLY MORNING TEMPERATURES IN THE MID
TEENS TOWARD ROCKFORD TO AROUND 20 EAST. THESE ARE ABOUT 10 TO 15
DEGREES BELOW NORMAL.
TUESDAY AND TUESDAY NIGHT...UPPER LEVEL HEIGHTS WILL NOT RISE ANY
ON TUE WITH CYCLONIC FLOW IN COMPLETE CONTROL. HOWEVER...MOST
SHORT WAVE ENERGY IS LIKELY TO REMAIN TO THE NORTH AND EAST...SO
IT IS POSSIBLE TO SEE A LITTLE SCATTERING IN SOUTHERN AREAS. WITH
THE FIRST COLD POCKET OF AIR SHIFTING SLIGHTLY EAST OF THE
AREA...TEMPERATURES SHOULD MAKE IT BACK CLOSE TO TODAYS HIGHS.
WIND CHILLS WILL REMAIN IN THE MID TEENS TO MID 20S HOWEVER. A
SECOND COLD FRONT PUSHES THROUGH TOMORROW NIGHT ASSOCIATED WITH A
SHORT WAVE ROTATING AROUND THE PARENT LOW. THIS APPEARS STARVED
FOR DEEP MOISTURE BUT THE COLD AIR WILL BRING LOW TEMPERATURES
EVEN COOLER TUE NIGHT AND WIND CHILLS BELOW ZERO FOR WED MORNING.
WEDNESDAY AND THURSDAY...DUE TO SUCCESSIVE COLD FRONTS AND LIKELY
BROKEN TO OVERCAST STRATOCU GIVEN FORECAST SOUNDINGS FOR
WED...THIS SHOULD BE THE DAY WITH THE COLDEST HIGH TEMPERATURE. IN
FACT...THE HIGH TEMPERATURE FORECAST /22/ REMAINS A TIED RECORD
LOW MAXIMUM FOR ROCKFORD ON MARCH 20TH. BACKWARD PARCEL
TRAJECTORIES FROM THE GFS IN THIS TIME INDICATE THE AIR MASS
SOURCE REGION TO BE THE NORTHERN PROVINCES OF CANADA...NOT A
TYPICAL SOURCE REGION FOR LATE MARCH FOR THIS AREA. DEPENDING ON
CLOUD COVER WED NIGHT AND THE AMOUNT WINDS EASE...LOWS MAY ALSO
APPROACH RECORD LEVELS AS THE NEXT COLD POCKET OF AIR MOVES OVER
THE AREA /850MB TEMPS OF -15C TO -17C/. THIS NEXT COLD SURGE
ACTUALLY REORIENTS THE LOW-LEVEL WINDS TO MORE NORTHERLY AND THUS
LOOKS TO PRESENT AT LEAST THE POTENTIAL FOR LAKE EFFECT SNOW TO
SHIFT TOWARD NORTHWEST INDIANA WED NIGHT INTO THU. HAVE UPPED
CHANCES THERE AND CERTAINLY ACCUMULATING SNOW OF A FEW INCHES OR
MORE COULD BE REALIZED IF A FOCUSED AREA DEVELOPS...WHICH SUCH
DETAILS BEING DIFFICULT TO DETERMINE AT THIS FORECAST DISTANCE.
THURSDAY WILL BEGIN TO SEE MARGINAL MODIFICATION IN TEMPERATURES.
BEYOND...WITH THE ACTIVE SHORT TERM NOT OVERLY MUCH TIME SPENT ON
THIS FORECAST PERIOD. THE PATTERN LOOKS TO REMAIN BLOCKED OVER THE
WEEKEND...WITH CONFIDENCE INCREASING SOMEWHAT THAT THE MAIN STORM
TRACK WILL BE TO THE SOUTH OF THE AREA AND GENERAL HIGH PRESSURE
IN THE REGION. HIGH TEMPERATURES LOOK TO BE 5 TO 10 DEGREES BELOW
NORMAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* MVFR CIGS GRADUALLY IMPROVING OVERNIGHT...WITH A FEW SNOW
FLURRIES OR ISOLATED SNOW SHOWERS ESPECIALLY PRIOR TO 06Z.
* VERY GUSTY WEST WINDS AROUND 30 KTS.
RATZER
//DISCUSSION...UPDATED 00Z...
COLD FRONT PLOWING EAST ACROSS NORTHERN/NORTHEAST IL AT THIS TIME.
BAND OF LIGHT PRECIP/IFR CIGS WITH THE FRONT WILL LIKELY GIVE A
BRIEF PERIOD OF 900-1000 FT CIG WITH 4-5SM VIS REDUCTION IN
RA/SN THROUGH PERHAPS 01Z...THEN LOOKS LIKE QUICK IMPROVEMENT
ABOVE 1500 FT...LIKELY INTO THE 2000-2500 FT FOR THE EVENING.
HIGHER END MVFR CIGS SHOULD THE CONTINUE TO SLOWLY RISE INTO EARLY
WEDNESDAY AS COLDER/DRIER AIR MOVES IN. STEEP LAPSE RATES WILL
LIKELY SUPPORT A PERIOD OF FLURRIES THIS EVENING/NIGHT...WITH THE
POTENTIAL FOR A FEW STRONGER SNOW SHOWERS WITH SOME VISIBILITY
REDUCTION...THOUGH LOW LEVEL INSTABILITY WILL BE FIGHTING
INCREASING LARGE SCALE SUBSIDENCE BEHIND DEPARTING LOW PRESSURE
SYSTEM AND DO NOT EXPECT THE HEAVIER SNOW SHOWERS TO BE WIDESPREAD
ENOUGH TO CARRY IN INDIVIDUAL TAFS.
WINDS HAVE SHIFTED TO THE WEST...AND WILL REMAIN WEST FOR THE
DURATION OF THE FORECAST. SUSTAINED SPEEDS NEAR 20 KT AND GUSTS
AROUND 30 KT SHOULD PERSIST THROUGH THE PERIOD...WITH A MORE
NOTICEABLE GRADUAL DECREASE LATER WEDNESDAY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE ALL ELEMENTS...EXCEPT LOW CONFIDENCE IN BRIEF
VSBY REDUCTION IN SHSN TONIGHT.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY THROUGH SUNDAY...MVFR CIGS PSBL WED WITH GUSTY WEST WINDS.
OTHERWISE MAINLY VFR.
RATZER
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 PM
TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
952 PM CDT MON MAR 18 2013
.DISCUSSION...
345 PM CDT
WHILE THE TRUE VERNAL EQUINOX ARRIVES WEDNESDAY...AND WE ARE THREE
WEEKS INTO METEOROLOGICAL WINTER...THE MAIN WEATHER HEADLINE THIS
WEEK WILL BE HOW UNSPRING-LIKE THE TEMPERATURES WILL BE. THIS
PRESENTS THE MAIN FORECAST CHALLENGE...ALONG WITH ANY SMALL
CHANCES FOR SNOW SHOWERS.
SYNOPSIS AND LATE THIS AFTERNOON...THE POTENT UPPER LEVEL LOW IS
MOVING EAST ACROSS MN THIS AFTERNOON...WITH THE MID-LEVEL JET AND
A VORT LOBE OF THE SYSTEM RUSHING EASTWARD OVER NORTHERN IL.
ENHANCEMENT ON THE LEADING EDGE OF THESE STEEPER MID-LEVEL LAPSE
RATES AND CONVERGENCE IS SEEN IN SNOW SHOWERS TRAVERSING NORTHEAST
ILLINOIS AS OF 3 PM. SPOTTIER HEAVIER SNOWFALL RATES WILL BE SEEN
IN THIS ACTIVITY AS IT DEPARTS. THE SURFACE ARCTIC FRONT OF THIS
SYSTEM IS CROSSING THE MISSISSIPPI RIVER AND WILL MOVE THROUGH THE
ENTIRE CWA BETWEEN 5 AND 9 PM. THIS WILL TURN THE SYNOPTIC PATTERN
TO ONE OF NORTHWEST FLOW AND COLD WHICH WILL CONTINUE TO REINFORCE
ITSELF THROUGH THE WEEK AS THE UPPER AND SURFACE LOWS EXPAND AND
SLOW ACROSS THE CENTRAL AND EASTERN GREAT LAKES. NUMEROUS SHORT
WAVE IMPULSES ARE EXPECTED TO RIDE AROUND THIS FEATURE WITH
MINIMAL CAUSES FOR SNOW...BUT EACH DRIVING COLD SURGES BACK INTO
THE AREA.
TONIGHT...SHORT TERM GUIDANCE IS IN GOOD AGREEMENT ON THE TIMING
OF THE ARCTIC FRONT THIS EVENING...ALONG WITH AGREEING THAT THE
STEEPENING OF THE LOW-LEVEL LAPSE RATES WILL LIKELY PRODUCE
SURFACE-BASED INSTABILITY. FORECAST SOUNDINGS FROM THE RAP YIELD
AROUND 50 J/KG OF MLCAPE ALONG AND IMMEDIATELY BEHIND THE FRONT.
THE SATURATED DEPTH AT THE TOP OF THIS MIXED LAYER IS QUITE
SHALLOW BUT MOST CONVECTIVE-ALLOWING ARW AND WRF GUIDANCE DO
CONTINUE TO PRODUCE A SPATTERING OF HIGHER REFLECTIVITY INDICATIVE
OF SNOW SHOWERS. WILL CARRY FLURRIES WITH A MENTION OF ISOLATED TO
SCATTERED SNOW SHOWERS.
THE FRONT WILL BRING BOTH STRONG HEIGHT AND PRESSURE RISES WHICH
ARE LINED UP WELL WITH A UNIDIRECTIONAL WIND COLUMN IN THE LOW-
LEVELS. THE TOP OF THE MIXED LAYER ON THE LATEST RAP GUIDANCE AS
WELL AS LOCAL ARW DOES YIELD 40 MPH GUSTS THIS EVENING. HAVE
INCLUDED SUCH GUSTS IMMEDIATELY BEHIND THE FRONT AND WOULD NOT BE
SURPRISED IF SOME PLACES IN THE SOUTHWEST FORECAST AREA COME IN A
BIT HIGHER. IF SNOW SHOWERS DO DEVELOP...SOME NOTABLE REDUCTIONS
IN VISIBILITY MAY BE SEEN DUE TO THE COMBINATION OF WINDS AND
SNOWFALL. WITH TEMPERATURES FALLING QUICKLY...WIND CHILLS IN THE
NORTHWEST FORECAST AREA LOOK TO ALREADY BE IN THE SINGLE DIGITS
BY 9 PM THIS EVENING. THIS DEGREE OF COLD AIR WILL SWEEP OVER THE
ENTIRE FORECAST AREA WITH EARLY MORNING TEMPERATURES IN THE MID
TEENS TOWARD ROCKFORD TO AROUND 20 EAST. THESE ARE ABOUT 10 TO 15
DEGREES BELOW NORMAL.
TUESDAY AND TUESDAY NIGHT...UPPER LEVEL HEIGHTS WILL NOT RISE ANY
ON TUE WITH CYCLONIC FLOW IN COMPLETE CONTROL. HOWEVER...MOST
SHORT WAVE ENERGY IS LIKELY TO REMAIN TO THE NORTH AND EAST...SO
IT IS POSSIBLE TO SEE A LITTLE SCATTERING IN SOUTHERN AREAS. WITH
THE FIRST COLD POCKET OF AIR SHIFTING SLIGHTLY EAST OF THE
AREA...TEMPERATURES SHOULD MAKE IT BACK CLOSE TO TODAYS HIGHS.
WIND CHILLS WILL REMAIN IN THE MID TEENS TO MID 20S HOWEVER. A
SECOND COLD FRONT PUSHES THROUGH TOMORROW NIGHT ASSOCIATED WITH A
SHORT WAVE ROTATING AROUND THE PARENT LOW. THIS APPEARS STARVED
FOR DEEP MOISTURE BUT THE COLD AIR WILL BRING LOW TEMPERATURES
EVEN COOLER TUE NIGHT AND WIND CHILLS BELOW ZERO FOR WED MORNING.
WEDNESDAY AND THURSDAY...DUE TO SUCCESSIVE COLD FRONTS AND LIKELY
BROKEN TO OVERCAST STRATOCU GIVEN FORECAST SOUNDINGS FOR
WED...THIS SHOULD BE THE DAY WITH THE COLDEST HIGH TEMPERATURE. IN
FACT...THE HIGH TEMPERATURE FORECAST /22/ REMAINS A TIED RECORD
LOW MAXIMUM FOR ROCKFORD ON MARCH 20TH. BACKWARD PARCEL
TRAJECTORIES FROM THE GFS IN THIS TIME INDICATE THE AIR MASS
SOURCE REGION TO BE THE NORTHERN PROVINCES OF CANADA...NOT A
TYPICAL SOURCE REGION FOR LATE MARCH FOR THIS AREA. DEPENDING ON
CLOUD COVER WED NIGHT AND THE AMOUNT WINDS EASE...LOWS MAY ALSO
APPROACH RECORD LEVELS AS THE NEXT COLD POCKET OF AIR MOVES OVER
THE AREA /850MB TEMPS OF -15C TO -17C/. THIS NEXT COLD SURGE
ACTUALLY REORIENTS THE LOW-LEVEL WINDS TO MORE NORTHERLY AND THUS
LOOKS TO PRESENT AT LEAST THE POTENTIAL FOR LAKE EFFECT SNOW TO
SHIFT TOWARD NORTHWEST INDIANA WED NIGHT INTO THU. HAVE UPPED
CHANCES THERE AND CERTAINLY ACCUMULATING SNOW OF A FEW INCHES OR
MORE COULD BE REALIZED IF A FOCUSED AREA DEVELOPS...WHICH SUCH
DETAILS BEING DIFFICULT TO DETERMINE AT THIS FORECAST DISTANCE.
THURSDAY WILL BEGIN TO SEE MARGINAL MODIFICATION IN TEMPERATURES.
BEYOND...WITH THE ACTIVE SHORT TERM NOT OVERLY MUCH TIME SPENT ON
THIS FORECAST PERIOD. THE PATTERN LOOKS TO REMAIN BLOCKED OVER THE
WEEKEND...WITH CONFIDENCE INCREASING SOMEWHAT THAT THE MAIN STORM
TRACK WILL BE TO THE SOUTH OF THE AREA AND GENERAL HIGH PRESSURE
IN THE REGION. HIGH TEMPERATURES LOOK TO BE 5 TO 10 DEGREES BELOW
NORMAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* MVFR CIGS GRADUALLY IMPROVING OVERNIGHT...WITH A FEW SNOW
FLURRIES OR ISOLATED SNOW SHOWERS ESPECIALLY PRIOR TO 06Z.
* VERY GUSTY WEST WINDS AROUND 30 KTS.
RATZER
//DISCUSSION...UPDATED 00Z...
COLD FRONT PLOWING EAST ACROSS NORTHERN/NORTHEAST IL AT THIS TIME.
BAND OF LIGHT PRECIP/IFR CIGS WITH THE FRONT WILL LIKELY GIVE A
BRIEF PERIOD OF 900-1000 FT CIG WITH 4-5SM VIS REDUCTION IN
RA/SN THROUGH PERHAPS 01Z...THEN LOOKS LIKE QUICK IMPROVEMENT
ABOVE 1500 FT...LIKELY INTO THE 2000-2500 FT FOR THE EVENING.
HIGHER END MVFR CIGS SHOULD THE CONTINUE TO SLOWLY RISE INTO EARLY
WEDNESDAY AS COLDER/DRIER AIR MOVES IN. STEEP LAPSE RATES WILL
LIKELY SUPPORT A PERIOD OF FLURRIES THIS EVENING/NIGHT...WITH THE
POTENTIAL FOR A FEW STRONGER SNOW SHOWERS WITH SOME VISIBILITY
REDUCTION...THOUGH LOW LEVEL INSTABILITY WILL BE FIGHTING
INCREASING LARGE SCALE SUBSIDENCE BEHIND DEPARTING LOW PRESSURE
SYSTEM AND DO NOT EXPECT THE HEAVIER SNOW SHOWERS TO BE WIDESPREAD
ENOUGH TO CARRY IN INDIVIDUAL TAFS.
WINDS HAVE SHIFTED TO THE WEST...AND WILL REMAIN WEST FOR THE
DURATION OF THE FORECAST. SUSTAINED SPEEDS NEAR 20 KT AND GUSTS
AROUND 30 KT SHOULD PERSIST THROUGH THE PERIOD...WITH A MORE
NOTICEABLE GRADUAL DECREASE LATER WEDNESDAY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE ALL ELEMENTS...EXCEPT LOW CONFIDENCE IN BRIEF
VSBY REDUCTION IN SHSN TONIGHT.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY THROUGH SUNDAY...MVFR CIGS PSBL WED WITH GUSTY WEST WINDS.
OTHERWISE MAINLY VFR.
RATZER
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 PM
TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
626 PM CDT MON MAR 18 2013
.DISCUSSION...
345 PM CDT
WHILE THE TRUE VERNAL EQUINOX ARRIVES WEDNESDAY...AND WE ARE THREE
WEEKS INTO METEOROLOGICAL WINTER...THE MAIN WEATHER HEADLINE THIS
WEEK WILL BE HOW UNSPRING-LIKE THE TEMPERATURES WILL BE. THIS
PRESENTS THE MAIN FORECAST CHALLENGE...ALONG WITH ANY SMALL
CHANCES FOR SNOW SHOWERS.
SYNOPSIS AND LATE THIS AFTERNOON...THE POTENT UPPER LEVEL LOW IS
MOVING EAST ACROSS MN THIS AFTERNOON...WITH THE MID-LEVEL JET AND
A VORT LOBE OF THE SYSTEM RUSHING EASTWARD OVER NORTHERN IL.
ENHANCEMENT ON THE LEADING EDGE OF THESE STEEPER MID-LEVEL LAPSE
RATES AND CONVERGENCE IS SEEN IN SNOW SHOWERS TRAVERSING NORTHEAST
ILLINOIS AS OF 3 PM. SPOTTIER HEAVIER SNOWFALL RATES WILL BE SEEN
IN THIS ACTIVITY AS IT DEPARTS. THE SURFACE ARCTIC FRONT OF THIS
SYSTEM IS CROSSING THE MISSISSIPPI RIVER AND WILL MOVE THROUGH THE
ENTIRE CWA BETWEEN 5 AND 9 PM. THIS WILL TURN THE SYNOPTIC PATTERN
TO ONE OF NORTHWEST FLOW AND COLD WHICH WILL CONTINUE TO REINFORCE
ITSELF THROUGH THE WEEK AS THE UPPER AND SURFACE LOWS EXPAND AND
SLOW ACROSS THE CENTRAL AND EASTERN GREAT LAKES. NUMEROUS SHORT
WAVE IMPULSES ARE EXPECTED TO RIDE AROUND THIS FEATURE WITH
MINIMAL CAUSES FOR SNOW...BUT EACH DRIVING COLD SURGES BACK INTO
THE AREA.
TONIGHT...SHORT TERM GUIDANCE IS IN GOOD AGREEMENT ON THE TIMING
OF THE ARCTIC FRONT THIS EVENING...ALONG WITH AGREEING THAT THE
STEEPENING OF THE LOW-LEVEL LAPSE RATES WILL LIKELY PRODUCE
SURFACE-BASED INSTABILITY. FORECAST SOUNDINGS FROM THE RAP YIELD
AROUND 50 J/KG OF MLCAPE ALONG AND IMMEDIATELY BEHIND THE FRONT.
THE SATURATED DEPTH AT THE TOP OF THIS MIXED LAYER IS QUITE
SHALLOW BUT MOST CONVECTIVE-ALLOWING ARW AND WRF GUIDANCE DO
CONTINUE TO PRODUCE A SPATTERING OF HIGHER REFLECTIVITY INDICATIVE
OF SNOW SHOWERS. WILL CARRY FLURRIES WITH A MENTION OF ISOLATED TO
SCATTERED SNOW SHOWERS.
THE FRONT WILL BRING BOTH STRONG HEIGHT AND PRESSURE RISES WHICH
ARE LINED UP WELL WITH A UNIDIRECTIONAL WIND COLUMN IN THE LOW-
LEVELS. THE TOP OF THE MIXED LAYER ON THE LATEST RAP GUIDANCE AS
WELL AS LOCAL ARW DOES YIELD 40 MPH GUSTS THIS EVENING. HAVE
INCLUDED SUCH GUSTS IMMEDIATELY BEHIND THE FRONT AND WOULD NOT BE
SURPRISED IF SOME PLACES IN THE SOUTHWEST FORECAST AREA COME IN A
BIT HIGHER. IF SNOW SHOWERS DO DEVELOP...SOME NOTABLE REDUCTIONS
IN VISIBILITY MAY BE SEEN DUE TO THE COMBINATION OF WINDS AND
SNOWFALL. WITH TEMPERATURES FALLING QUICKLY...WIND CHILLS IN THE
NORTHWEST FORECAST AREA LOOK TO ALREADY BE IN THE SINGLE DIGITS
BY 9 PM THIS EVENING. THIS DEGREE OF COLD AIR WILL SWEEP OVER THE
ENTIRE FORECAST AREA WITH EARLY MORNING TEMPERATURES IN THE MID
TEENS TOWARD ROCKFORD TO AROUND 20 EAST. THESE ARE ABOUT 10 TO 15
DEGREES BELOW NORMAL.
TUESDAY AND TUESDAY NIGHT...UPPER LEVEL HEIGHTS WILL NOT RISE ANY
ON TUE WITH CYCLONIC FLOW IN COMPLETE CONTROL. HOWEVER...MOST
SHORT WAVE ENERGY IS LIKELY TO REMAIN TO THE NORTH AND EAST...SO
IT IS POSSIBLE TO SEE A LITTLE SCATTERING IN SOUTHERN AREAS. WITH
THE FIRST COLD POCKET OF AIR SHIFTING SLIGHTLY EAST OF THE
AREA...TEMPERATURES SHOULD MAKE IT BACK CLOSE TO TODAYS HIGHS.
WIND CHILLS WILL REMAIN IN THE MID TEENS TO MID 20S HOWEVER. A
SECOND COLD FRONT PUSHES THROUGH TOMORROW NIGHT ASSOCIATED WITH A
SHORT WAVE ROTATING AROUND THE PARENT LOW. THIS APPEARS STARVED
FOR DEEP MOISTURE BUT THE COLD AIR WILL BRING LOW TEMPERATURES
EVEN COOLER TUE NIGHT AND WIND CHILLS BELOW ZERO FOR WED MORNING.
WEDNESDAY AND THURSDAY...DUE TO SUCCESSIVE COLD FRONTS AND LIKELY
BROKEN TO OVERCAST STRATOCU GIVEN FORECAST SOUNDINGS FOR
WED...THIS SHOULD BE THE DAY WITH THE COLDEST HIGH TEMPERATURE. IN
FACT...THE HIGH TEMPERATURE FORECAST /22/ REMAINS A TIED RECORD
LOW MAXIMUM FOR ROCKFORD ON MARCH 20TH. BACKWARD PARCEL
TRAJECTORIES FROM THE GFS IN THIS TIME INDICATE THE AIR MASS
SOURCE REGION TO BE THE NORTHERN PROVINCES OF CANADA...NOT A
TYPICAL SOURCE REGION FOR LATE MARCH FOR THIS AREA. DEPENDING ON
CLOUD COVER WED NIGHT AND THE AMOUNT WINDS EASE...LOWS MAY ALSO
APPROACH RECORD LEVELS AS THE NEXT COLD POCKET OF AIR MOVES OVER
THE AREA /850MB TEMPS OF -15C TO -17C/. THIS NEXT COLD SURGE
ACTUALLY REORIENTS THE LOW-LEVEL WINDS TO MORE NORTHERLY AND THUS
LOOKS TO PRESENT AT LEAST THE POTENTIAL FOR LAKE EFFECT SNOW TO
SHIFT TOWARD NORTHWEST INDIANA WED NIGHT INTO THU. HAVE UPPED
CHANCES THERE AND CERTAINLY ACCUMULATING SNOW OF A FEW INCHES OR
MORE COULD BE REALIZED IF A FOCUSED AREA DEVELOPS...WHICH SUCH
DETAILS BEING DIFFICULT TO DETERMINE AT THIS FORECAST DISTANCE.
THURSDAY WILL BEGIN TO SEE MARGINAL MODIFICATION IN TEMPERATURES.
BEYOND...WITH THE ACTIVE SHORT TERM NOT OVERLY MUCH TIME SPENT ON
THIS FORECAST PERIOD. THE PATTERN LOOKS TO REMAIN BLOCKED OVER THE
WEEKEND...WITH CONFIDENCE INCREASING SOMEWHAT THAT THE MAIN STORM
TRACK WILL BE TO THE SOUTH OF THE AREA AND GENERAL HIGH PRESSURE
IN THE REGION. HIGH TEMPERATURES LOOK TO BE 5 TO 10 DEGREES BELOW
NORMAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* BRIEF OVC009-010 IFR CIG THROUGH 01Z WITH SOME LGT PCPN WITH
COLD FRONT...THEN RAPIDLY IMPROVING ABOVE 1500 FT.
* MVFR CIGS SHOULD GRADUALLY IMPROVE ABOVE 2000 FT AGL THIS EVE...
WITH A FEW SNOW FLURRIES OR ISOLATED SNOW SHOWERS.
* VERY GUSTY WEST WINDS AROUND 30 KTS.
RATZER
//DISCUSSION...UPDATED 00Z...
COLD FRONT PLOWING EAST ACROSS NORTHERN/NORTHEAST IL AT THIS TIME.
BAND OF LIGHT PRECIP/IFR CIGS WITH THE FRONT WILL LIKELY GIVE A
BRIEF PERIOD OF 900-1000 FT CIG WITH 4-5SM VIS REDUCTION IN
RA/SN THROUGH PERHAPS 01Z...THEN LOOKS LIKE QUICK IMPROVEMENT
ABOVE 1500 FT...LIKELY INTO THE 2000-2500 FT FOR THE EVENING.
HIGHER END MVFR CIGS SHOULD THE CONTINUE TO SLOWLY RISE INTO EARLY
WEDNESDAY AS COLDER/DRIER AIR MOVES IN. STEEP LAPSE RATES WILL
LIKELY SUPPORT A PERIOD OF FLURRIES THIS EVENING/NIGHT...WITH THE
POTENTIAL FOR A FEW STRONGER SNOW SHOWERS WITH SOME VISIBILITY
REDUCTION...THOUGH LOW LEVEL INSTABILITY WILL BE FIGHTING
INCREASING LARGE SCALE SUBSIDENCE BEHIND DEPARTING LOW PRESSURE
SYSTEM AND DO NOT EXPECT THE HEAVIER SNOW SHOWERS TO BE WIDESPREAD
ENOUGH TO CARRY IN INDIVIDUAL TAFS.
WINDS HAVE SHIFTED TO THE WEST...AND WILL REMAIN WEST FOR THE
DURATION OF THE FORECAST. SUSTAINED SPEEDS NEAR 20 KT AND GUSTS
AROUND 30 KT SHOULD PERSIST THROUGH THE PERIOD...WITH A MORE
NOTICEABLE GRADUAL DECREASE LATER WEDNESDAY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE IN TIMING.
* HIGH CONFIDENCE WINDS AND ALL OTHER ELEMENTS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY THROUGH SUNDAY...MVFR CIGS PSBL WED WITH GUSTY WEST WINDS.
OTHERWISE MAINLY VFR.
RATZER
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...10 PM
MONDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
512 PM CDT SUN MAR 17 2013
.DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* GUSTY EAST WINDS DIMINISHING FOR A TIME THIS EVENING...THEN
INCREASING FROM THE EAST-SOUTHEAST OVERNIGHT.
* POTENTIAL FOR MIX OF SN/PL INCREASES APPROACHING 12Z MONDAY.
MVFR CIGS EXPECTED...IFR POSSIBLE.
RATZER
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM-HIGH CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
319 PM CDT SUN MAR 17 2013
.DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
242 PM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
234 PM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LAKE EFFECT MVFR/VFR CIGS BECOMING SCATTERED CLOUDS MID TO LATE
AFTERNOON.
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1239 PM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LAKE EFFECT MVFR/VFR CIGS BECOMING SCATTERED CLOUDS MID TO LATE
AFTERNOON.
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1104 AM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* LAKE EFFECT MVFR/VFR CIGS CONTINUING THROUGH MID AFTERNOON.
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1011 AM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
&&
.PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* LAKE EFFECT MVFR/VFR CIGS CONTINUING THROUGH MID AFTERNOON.
* NORTH TO NORTHEAST WINDS BECOMING MORE EASTERLY BY LATE
MORNING...AND THEN EAST TO SOUTHEAST THIS EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
910 AM CDT SUN MAR 17 2013
.DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* LAKE EFFECT MVFR/VFR CIGS CONTINUING THROUGH MID AFTERNOON.
* NORTH TO NORTHEAST WINDS BECOMING MORE EASTERLY BY LATE
MORNING...AND THEN EAST TO SOUTHEAST THIS EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
650 AM CDT SUN MAR 17 2013
.DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* LAKE EFFECT MVFR CIGS LIKELY RETURNING MID/LATE MORNING THROUGH
EARLY/MID AFTERNOON.
* NORTH-NORTHEAST WINDS TURNING EAST-NORTHEAST INTO THE
AFTERNOON...THEN EAST-SOUTHEAST THIS EVENING.
* MIXED PRECIPITATION CHANCES INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
MDB
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM-HIGH CONFIDENCE IN MVFR CIGS RETURNING MID/LATE
MORNING...MEDIUM CONFIDENCE IN TIMING OF ARRIVAL/DEPARTURE.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM CONFIDENCE IN PRECIP ARRIVING MONDAY MORNING...LOW-MEDIUM
CONFIDENCE IN TIMING...MEDIUM CONFIDENCE IN PRECIP TYPE TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
405 AM CDT SUN MAR 17 2013
.DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* HIGH END MVFR CIGS SCATTERING NEXT HOUR OR SO.
* MVFR CIGS LIKELY RETURNING FOR A FEW HOURS MID/LATE MORNING.
* NORTH WINDS TURN NORTHEAST THROUGH MID MORNING...THEN EAST-
SOUTHEAST LATE THIS AFTERNOON/EARLY THIS EVENING.
MDB
//DISCUSSION...UPDATED 09Z...
EDGE OF HIGH END MVFR CIGS JUST NOW CROSSING THE NORTHERN CHICAGO
METRO AND EXPECT IT TO WORK SOUTHWARD ACROSS THE CHI TERMINALS IN
THE NEXT HOUR OR SO. CHANCE FOR MVFR LAKE EFFECT CIGS TO RETURN
STILL ON TRACK FROM MID MORNING ONWARD AS FLOW TURNS
NORTHEASTERLY.
MDB
FROM 06Z...
HIGH PRESSURE IS SPREADING SOUTHWARD INTO THE UPPER MISSISSIPPI
RIVER VALLEY AND NORTHERN PLAINS EARLY TONIGHT WHILE A WEAK LOW
PRESSURE SYSTEM MOVES ACROSS LAKE HURON. WINDS WILL TURN TO THE
NORTH THEN NORTHEAST THROUGH MID/LATE MORNING AND EVENTUALLY TURN
TO THE EAST-SOUTHEAST LATE THIS AFTERNOON AND EARLY THIS EVENING
AS THE HIGH CROSSES LAKE MICHIGAN. MVFR CIGS CONTINUE ACROSS THE
TERMINALS BUT SCATTERING/CLEARING IS SPREADING SOUTHEASTWARD
TOWARDS THE AREA SO EXPECT THAT SKIES WILL SCATTER IN THE NEXT FEW
HOURS. GYY WILL BE THE WILDCARD AS FLOW WILL CONTINUE DOWN LAKE
MICHIGAN WHICH MAY KEEP BKN-OVC MVFR CIGS IN PLACE CONTINUOUSLY
THROUGH MIDDAY. MVFR LAKE CLOUDS HAVE A GOOD CHANCE OF RETURNING
TO ORD/MDW/DPA AS WELL DURING THE MID MORNING HOURS. SOME FLURRIES
ARE A POSSIBILITY UNDER ANY LAKE CLOUD COVER. LAKE PARAMETERS
BECOME LESS FAVORABLE DURING THE AFTERNOON SO EXPECT A DECREASE IN
CLOUD COVERAGE DURING THAT TIME. VFR WILL THEN PREVAIL INTO EARLY
MONDAY BUT AN APPROACHING SYSTEM WILL SPREAD MVFR CIGS BACK INTO
THE AREA TOWARD DAYBREAK ALONG WITH A CHANCE FOR SOME MIXED
PRECIPITATION BY MID MORNING MONDAY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM-HIGH CONFIDENCE IN CLOUD COVERAGE TRENDS/TIMING.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...MIX OF SN/RA...PSBLY FZRA EARLY. MVFR LIKELY IFR
POSSIBLE.
TUESDAY THROUGH FRIDAY...MAINLY VFR.
RATZER
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1252 PM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 335 AM CDT SUN MAR 17 2013
LATEST SFC ANALYSIS WAS INDICATING LARGE AND SEASONABLY STRONG RIDGE
COMPLEX ENGULFING MUCH OF THE UPPER MIDWEST WITH A NEAR 1030 MB
CENTER JUST NORTH OF THE NORTHWEST CORNER ON MN. SOUTHEAST RETURN
FLOW AND SFC PRESSURE GRADIENT TIGHTENING AND ORGANIZING ACRS THE
NORTHWESTERN HIGH PLAINS IN A REGION ALSO BATHED BY ROBUST PRESSURE
FALLS. ALOFT...WATER VAPOR IMAGERY WAS INDICATING A VIGOROUS UPPER
LEVEL WAVE ROLLING IN OFF THE PACIFIC AND ACRS OR/WA ATTM WITH AN
ASSOCIATED BAROCLINIC LEAF PLUME TO THE LEE OF IT ACRS THE WESTERN
ROCKIES. TO THE SOUTH ALONG TIGHTER LLVL BAROCLINIC RIBBON...AN
ISENTROPIC LIFT PRECIP EVENT WAS ONGOING ACRS KS...MO AND INTO
SOUTHERN IL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
TODAY...THE ABOVE MENTIONED STRONG RIDGE OF HIGH PRESSURE WILL LOOK
TO SQUEEZE EASTWARD ACRS THE WESTERN GRT LKS TODAY. AS IT DOES...
IT/S DRYING NORTHEAST TO EASTERLY FETCH IN THE BOUNDARY LAYER OR EVEN
DEEPER SHOULD KEEP MOST OF THE OVERRUNNING PRECIP OFF THE UPGLIDE
PROCESS TO THE SOUTH OF THE CWA. BUT WILL KEEP THE ONGOING MENTION
OF SPRINKLES OR A SLIGHT CHC OF LIGHT RAIN IN THE FAR SOUTH THIS
AFTERNOON. CLOUD COVER AND IT/S EFFECT ON TEMPS THE MAIN CHALLENGE
TODAY. THE RAP SEEMS TO HAVE SOME HANDEL ON CURRENT LLVL STRATUS
TRENDS PUSHING SOUTHWARD. AFTER MUCH OF THESE LOWER CLOUDS PUSH
ALMOST OUT OF THE DVN CWA...THE VEERING NORTHERLY FLOW SUGGESTED
BY THE RAP THEN SLOSHES BACK SOME LOWER LEVEL STRATUS BACK ACRS
MUCH OF THE DVN CWA FROM THE EAST AND NORTHEAST THIS MORNING UNDER
THE ONGOING AND SUBSTANTIAL TRAPPING INVERSION BASED AT H85 TO H75
MB. WITH PLUME OF MID AND UPPER LEVEL CLOUDS STREAMING OFF THE
OVERRUNNING PRECIP AND CONVECTION ACRS KS INTO MO...WITH THE CHANCE
OF THE STRATUS COMING BACK WILL KEEP THE FLAVOR OF THE DAY MOSTLY
CLOUDY ALTHOUGH SOME PEAKS OF SUN AT TIMES PROBABLE NORTH OF I80.
WILL KEEP HIGH TEMPS MAINLY IN THE 30S FOR A CHILLY ST PATRICK/S
DAY...BUT AREAS ALONG AND SOUTH OF I80 MAY GET NEAR 40 WITH SOME
CLOUD THINNING AT TIMES.
TONIGHT...THE DVN CWA TO BE MAINLY IN BETWEEN TWO LIFTING/FORCING
PROCESSES FOR MUCH OF THE NIGHT. THE ABOVE MENTIONED VIGOROUS UPPER
LEVEL WAVE CURRENTLY ACRS THE PACIFIC NORTHWEST WILL CONTINUE TO DIG
ACRS THE NORTHERN PLAINS AND MO RVR VALLEY THROUGH 12Z MON...WITH
UPPER LEVEL TROFFINESS EXTENDING ALL THE WAY DOWN INTO THE
SOUTHEASTERN PLAINS. CONCEPTUALLY THIS SHOULD ALLOW LLVL CYCLOGENESIS
BLOSSOM ACRS THE SOUTHEASTERN PLAINS AN UP THE LOWER TO MID MS RVR
VALLEY. NORTHWESTERN REACHING FLANK OF DEF ZONE PRECIP OFF THIS
FEATURE MAY CLIP THE SOUTHERN AND SOUTHEASTERN CWA THIS EVENING AND
INTO THE OVERNIGHT...BUT DRY LOW TO MID LEVELS WILL HAVE TO BE
OVERCOME. WILL KEEP CHC POPS IN THESE AREAS FOR LIGHT RAIN THIS
EVENING...BECOMING MIXED WITH SNOW OR SLEET INTO EARLY MON MORNING
AS EVAPO COOLING PROCESSES HAVE THEIR AFFECT. SFC TEMPS IN THESE
AREAS WILL BE MARGINAL FOR ANY FREEZING RAIN THREAT AND WILL NOT
MENTION. BUT THE MAIN FORCING EVENT IN VIEW OF THE APPROACHING
DIGGING WAVE WILL LOOK TO OCCUR ACRS THE NORTHEASTERN PLAINS INTO MN
AND IA LATER TONIGHT. DEEPENING SFC LOW PRESSURE TO UNDER 1000 MB TO
ROLL OUT OF THE DAKOTAS AND INTO NORTHWESTERN MN BY 12Z MON. THE
TROF ALMOST TAKING A NEG TILT AS IT DOES SUGGESTS A STRONGLY FORCED
EVENT ACRS THE UPPER MS RVR VALLEY REGION. ASSOCIATED PRECIP SWATH
AHEAD OF THIS PROCESS WILL LOOK TO PUSH ACRS IA AND INTO THE WESTERN/
NORTHWESTERN THIRD OF THE DVN CWA AFTER 08Z MON MORNING MAINLY IN
THE FORM OF SNOW. UPWARD VERTICAL VELOCITIES AND THERMODYNAMIC
PROFILES SUGGEST A BURST OF HEAVY WET SNOW POSSIBLE INTO THE FAR
NORTHWESTERN CWA WHERE UP TO AN INCH OF SNOW MAY OCCUR BY 12Z MON
NORTHWEST OF A CEDAR RAPIDS...TO MANCHESTER IA LINE. UP TO A HALF
INCH POSSIBLE ALONG AND NORTHWEST OF AN IOWA CITY...TO DYERSVILLE
LINE. STILL RATHER MILD SFC/GROUND TEMPS TO ACT AS AN ACCUMULATION
INHIBITOR AND PROMOTE COMPACTION AND MELTING EVENTUALLY. BUT SNOW
RATES BEFORE THE SUN RISES MAY STILL OVERCOME THIS FOR A WHILE TO
ALLOW THE POTENTIAL ACCUMS MENTIONED ABOVE. REST OF THE EVENT COVERED
IN DISCUSSION BELOW. ..12..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 17 2013
SNOW AMOUNTS MONDAY MORNING WILL BE THE MAIN CONCERN FOR THE LONG
TERM. AFTER MONDAY NORTHWEST FLOW TO DOMINATE THE REGION KEEPING
COLD AND DRY CONDITIONS OVER THE AREA INTO THE WEEKEND.
A SHORTWAVE OVER THE PACIFIC NORTHWEST EARLY THIS MORNING IS PROGGED
TO MOVE THROUGH THE MID AND UPPER MISSISSIPPI VALLEY MONDAY. THE
S/W WILL DRAG A STRONG COLD FRONT THROUGH THE REGION MONDAY
AFTERNOON AND EVENING WITH VERY COLD TEMPERATURES RUSHING INTO THE
REGION MONDAY AFTERNOON/NIGHT. THE FORECAST MODELS ARE IN GOOD
AGREEMENT IN SPREADING THE SYNOPTIC FORCING AHEAD OF THIS SYSTEM
OVER THE CWFA MONDAY MORNING WITH THE BETTER FORCING CLIPPING THE
NORTHERN COUNTIES. WITH PW/S EXPECTED TO BE AROUND A HALF INCH OR
SO QPF AMOUNTS OF 1 TO 2 TENTHS OF AN INCH LOOK REASONABLE BETWEEN
12Z AND 18Z. H8 TEMPS MONDAY MORNING WILL BE JUST BELOW ZERO
SUPPORTING SNOW RATIOS AROUND 10 TO 1 EARLY MONDAY MORNING WITH
RATIOS INCREASING TO 15 TO 1 BY LATE MORNING AS THE COLDER AIR
REACHES THE AREA. THE EXPECTED QPF AND SNOW RATIOS SUPPORT SNOWFALL
AMOUNTS IN THE 1 TO 2 INCH RANGE /STORM TOTAL/ NORTH OF I80 WITH THE
LOWER AMOUNTS NEAR I80 AND THE HIGHER AMOUNTS ALONG THE HIGHWAY 20
CORRIDOR. THE BIGGEST IMPACTS FROM THE SNOW MAY BE THE TIMING AND
LOW VISIBILITIES. THE SNOW WILL IMPACT THE MORNING COMMUTE
ESPECIALLY OVER EAST CENTRAL IOWA BUT SURFACE TEMPERATURES DURING
THE SNOW SHOULD BE IN THE UPPER 20S TO LOW 30S SUGGESTING MOST OF
THE SNOW WILL HAVE A DIFFICULT TIME ACCUMULATING ON ROADS. THE
OTHER AREA OF CONCERN WILL BE REDUCED VISIBILITIES. MODELS ARE
SHOWING A NARROW BAND OF FGEN WITH GOOD VERTICAL CONTINUITY AND ON
THE GRADIENT OF STEEPER MID LEVEL LAPSE RATES SUGGESTING A NARROW
BAND OF ENHANCED SNOWFALL RATES. IT ALSO APPEARS THAT THE THERMAL
PROFILES WILL SUPPORT DENDRITIC FLAKES DURING THE PERIOD OF ENHANCED
FORCING. IF THESE CONDITIONS VERIFY THEN VISIBILITIES DROPPING TO A
HALF MILE OR LESS WILL BE POSSIBLE AT TIMES MONDAY MORNING.
THE ACCUMULATING SNOW WILL END BY NOON IN THE NORTHEAST AS THE
BETTER FORCING MOVES EAST OF THE AREA. COLDER AIR AND STRONGER WINDS
MOVE IN DURING THE AFTERNOON CAUSING FALLING TEMPERATURES DURING THE
MID TO LATE AFTERNOON OVER THE NORTHWEST COUNTIES. THE BRISK
CONDITIONS WILL CONTINUE OVER NIGHT AS A SURFACE LOW MOVES THROUGH
THE WESTERN GREAT LAKES AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
MID/LOWER MISSOURI VALLEY. LOWS TUESDAY MORNING ARE EXPECTED TO
RANGE FROM AROUND 10 IN THE NORTH TO THE MID 20S SOUTH.
THE REST OF THE WEEK LOOKS COLD AND DRY WITH NORTHWEST FLOW
REMAINING OVER THE AREA BETWEEN A BROAD EASTERN US TROF AND RIDGING
OVER THE WESTERN U.S./EASTERN PACIFIC. A REINFORCING SHOT OF COLD
AIR IS PROGGED TO MOVE INTO THE REGION TUESDAY NIGHT RESULTING IN
SINGLE DIGIT LOWS NORTH AND AROUND 20 IN THE SOUTH WEDNESDAY MORNING
AND HIGHS WEDNESDAY IN THE LOW TO MID 20S NORTH TO MID 30S SOUTH.
AFTER WEDNESDAY TEMPERATURES WILL MODERATE A LITTLE WITH HIGHS
EXPECTED TO BE IN THE 30S TO LOW 40S AND LOWS IN THE 20S BY FRIDAY
AND SATURDAY. BUT THESE TEMPERATURES ARE STILL WELL BELOW NORMAL AS
WE APPROACH THE LAST WEEK OF MARCH.
DLF
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1237 PM CDT SUN MAR 17 2013
MVFR TO VFR CIGS EXPECTED FOR MUCH OF TONIGHT. LOW PRESSURE WILL
MOVE FROM THE NORTHERN PLAINS TO LAKE SUPERIOR BY MONDAY NIGHT.
WARM...MOIST ADVECTION IN ADVANCE OF THIS SYSTEM WILL RESULT IN
PRECIPITATION DEVELOPING OVER THE TERMINALS FROM SOUTH TO NORTH
MAINLY OVERNIGHT THROUGH MONDAY MORNING...WITH CONDITIONS LOWERING
TO GENERALLY IFR IN EITHER CIGS AND/OR VSBY. SOUNDINGS SUGGEST
COULD SEE WINTRY MIX OF PRECIPITATION ESPECIALLY AT KBRL AND KMLI
WITH MAINLY SNOW AT KCID AND KDBQ WHERE ACCUMULATIONS OF AN INCH
OR TWO APPEAR LIKELY. PRECIPITATION IS EXPECTED TO END OR TAPER
OFF BY MID TO LATE MORNING FROM SOUTHWEST TO NORTHEAST WITH
CONDITIONS BECOMING MOSTLY MVFR. WINDS EASTERLY AROUND 10 KTS
THROUGH MUCH OF TONIGHT...WITH SOME GUSTS NEAR 18 KTS REST OF THIS
AFTERNOON. LIGHT WINDS MAINLY SOUTHEAST MONDAY TO BECOME WESTERLY
AND INCREASE TO 10-20 KTS BY MIDDAY.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
647 AM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 335 AM CDT SUN MAR 17 2013
LATEST SFC ANALYSIS WAS INDICATING LARGE AND SEASONABLY STRONG RIDGE
COMPLEX ENGULFING MUCH OF THE UPPER MIDWEST WITH A NEAR 1030 MB
CENTER JUST NORTH OF THE NORTHWEST CORNER ON MN. SOUTHEAST RETURN
FLOW AND SFC PRESSURE GRADIENT TIGHTENING AND ORGANIZING ACRS THE
NORTHWESTERN HIGH PLAINS IN A REGION ALSO BATHED BY ROBUST PRESSURE
FALLS. ALOFT...WATER VAPOR IMAGERY WAS INDICATING A VIGOROUS UPPER
LEVEL WAVE ROLLING IN OFF THE PACIFIC AND ACRS OR/WA ATTM WITH AN
ASSOCIATED BAROCLINIC LEAF PLUME TO THE LEE OF IT ACRS THE WESTERN
ROCKIES. TO THE SOUTH ALONG TIGHTER LLVL BAROCLINIC RIBBON...AN
ISENTROPIC LIFT PRECIP EVENT WAS ONGOING ACRS KS...MO AND INTO
SOUTHERN IL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
TODAY...THE ABOVE MENTIONED STRONG RIDGE OF HIGH PRESSURE WILL LOOK
TO SQUEEZE EASTWARD ACRS THE WESTERN GRT LKS TODAY. AS IT DOES...
IT/S DRYING NORTHEAST TO EASTERLY FETCH IN THE BOUNDARY LAYER OR EVEN
DEEPER SHOULD KEEP MOST OF THE OVERRUNNING PRECIP OFF THE UPGLIDE
PROCESS TO THE SOUTH OF THE CWA. BUT WILL KEEP THE ONGOING MENTION
OF SPRINKLES OR A SLIGHT CHC OF LIGHT RAIN IN THE FAR SOUTH THIS
AFTERNOON. CLOUD COVER AND IT/S EFFECT ON TEMPS THE MAIN CHALLENGE
TODAY. THE RAP SEEMS TO HAVE SOME HANDEL ON CURRENT LLVL STRATUS
TRENDS PUSHING SOUTHWARD. AFTER MUCH OF THESE LOWER CLOUDS PUSH
ALMOST OUT OF THE DVN CWA...THE VEERING NORTHERLY FLOW SUGGESTED
BY THE RAP THEN SLOSHES BACK SOME LOWER LEVEL STRATUS BACK ACRS
MUCH OF THE DVN CWA FROM THE EAST AND NORTHEAST THIS MORNING UNDER
THE ONGOING AND SUBSTANTIAL TRAPPING INVERSION BASED AT H85 TO H75
MB. WITH PLUME OF MID AND UPPER LEVEL CLOUDS STREAMING OFF THE
OVERRUNNING PRECIP AND CONVECTION ACRS KS INTO MO...WITH THE CHANCE
OF THE STRATUS COMING BACK WILL KEEP THE FLAVOR OF THE DAY MOSTLY
CLOUDY ALTHOUGH SOME PEAKS OF SUN AT TIMES PROBABLE NORTH OF I80.
WILL KEEP HIGH TEMPS MAINLY IN THE 30S FOR A CHILLY ST PATRICK/S
DAY...BUT AREAS ALONG AND SOUTH OF I80 MAY GET NEAR 40 WITH SOME
CLOUD THINNING AT TIMES.
TONIGHT...THE DVN CWA TO BE MAINLY IN BETWEEN TWO LIFTING/FORCING
PROCESSES FOR MUCH OF THE NIGHT. THE ABOVE MENTIONED VIGOROUS UPPER
LEVEL WAVE CURRENTLY ACRS THE PACIFIC NORTHWEST WILL CONTINUE TO DIG
ACRS THE NORTHERN PLAINS AND MO RVR VALLEY THROUGH 12Z MON...WITH
UPPER LEVEL TROFFINESS EXTENDING ALL THE WAY DOWN INTO THE
SOUTHEASTERN PLAINS. CONCEPTUALLY THIS SHOULD ALLOW LLVL CYCLOGENESIS
BLOSSOM ACRS THE SOUTHEASTERN PLAINS AN UP THE LOWER TO MID MS RVR
VALLEY. NORTHWESTERN REACHING FLANK OF DEF ZONE PRECIP OFF THIS
FEATURE MAY CLIP THE SOUTHERN AND SOUTHEASTERN CWA THIS EVENING AND
INTO THE OVERNIGHT...BUT DRY LOW TO MID LEVELS WILL HAVE TO BE
OVERCOME. WILL KEEP CHC POPS IN THESE AREAS FOR LIGHT RAIN THIS
EVENING...BECOMING MIXED WITH SNOW OR SLEET INTO EARLY MON MORNING
AS EVAPO COOLING PROCESSES HAVE THEIR AFFECT. SFC TEMPS IN THESE
AREAS WILL BE MARGINAL FOR ANY FREEZING RAIN THREAT AND WILL NOT
MENTION. BUT THE MAIN FORCING EVENT IN VIEW OF THE APPROACHING
DIGGING WAVE WILL LOOK TO OCCUR ACRS THE NORTHEASTERN PLAINS INTO MN
AND IA LATER TONIGHT. DEEPENING SFC LOW PRESSURE TO UNDER 1000 MB TO
ROLL OUT OF THE DAKOTAS AND INTO NORTHWESTERN MN BY 12Z MON. THE
TROF ALMOST TAKING A NEG TILT AS IT DOES SUGGESTS A STRONGLY FORCED
EVENT ACRS THE UPPER MS RVR VALLEY REGION. ASSOCIATED PRECIP SWATH
AHEAD OF THIS PROCESS WILL LOOK TO PUSH ACRS IA AND INTO THE WESTERN/
NORTHWESTERN THIRD OF THE DVN CWA AFTER 08Z MON MORNING MAINLY IN
THE FORM OF SNOW. UPWARD VERTICAL VELOCITIES AND THERMODYNAMIC
PROFILES SUGGEST A BURST OF HEAVY WET SNOW POSSIBLE INTO THE FAR
NORTHWESTERN CWA WHERE UP TO AN INCH OF SNOW MAY OCCUR BY 12Z MON
NORTHWEST OF A CEDAR RAPIDS...TO MANCHESTER IA LINE. UP TO A HALF
INCH POSSIBLE ALONG AND NORTHWEST OF AN IOWA CITY...TO DYERSVILLE
LINE. STILL RATHER MILD SFC/GROUND TEMPS TO ACT AS AN ACCUMULATION
INHIBITOR AND PROMOTE COMPACTION AND MELTING EVENTUALLY. BUT SNOW
RATES BEFORE THE SUN RISES MAY STILL OVERCOME THIS FOR A WHILE TO
ALLOW THE POTENTIAL ACCUMS MENTIONED ABOVE. REST OF THE EVENT COVERED
IN DISCUSSION BELOW. ..12..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 17 2013
SNOW AMOUNTS MONDAY MORNING WILL BE THE MAIN CONCERN FOR THE LONG
TERM. AFTER MONDAY NORTHWEST FLOW TO DOMINATE THE REGION KEEPING
COLD AND DRY CONDITIONS OVER THE AREA INTO THE WEEKEND.
A SHORTWAVE OVER THE PACIFIC NORTHWEST EARLY THIS MORNING IS PROGGED
TO MOVE THROUGH THE MID AND UPPER MISSISSIPPI VALLEY MONDAY. THE
S/W WILL DRAG A STRONG COLD FRONT THROUGH THE REGION MONDAY
AFTERNOON AND EVENING WITH VERY COLD TEMPERATURES RUSHING INTO THE
REGION MONDAY AFTERNOON/NIGHT. THE FORECAST MODELS ARE IN GOOD
AGREEMENT IN SPREADING THE SYNOPTIC FORCING AHEAD OF THIS SYSTEM
OVER THE CWFA MONDAY MORNING WITH THE BETTER FORCING CLIPPING THE
NORTHERN COUNTIES. WITH PW/S EXPECTED TO BE AROUND A HALF INCH OR
SO QPF AMOUNTS OF 1 TO 2 TENTHS OF AN INCH LOOK REASONABLE BETWEEN
12Z AND 18Z. H8 TEMPS MONDAY MORNING WILL BE JUST BELOW ZERO
SUPPORTING SNOW RATIOS AROUND 10 TO 1 EARLY MONDAY MORNING WITH
RATIOS INCREASING TO 15 TO 1 BY LATE MORNING AS THE COLDER AIR
REACHES THE AREA. THE EXPECTED QPF AND SNOW RATIOS SUPPORT SNOWFALL
AMOUNTS IN THE 1 TO 2 INCH RANGE /STORM TOTAL/ NORTH OF I80 WITH THE
LOWER AMOUNTS NEAR I80 AND THE HIGHER AMOUNTS ALONG THE HIGHWAY 20
CORRIDOR. THE BIGGEST IMPACTS FROM THE SNOW MAY BE THE TIMING AND
LOW VISIBILITIES. THE SNOW WILL IMPACT THE MORNING COMMUTE
ESPECIALLY OVER EAST CENTRAL IOWA BUT SURFACE TEMPERATURES DURING
THE SNOW SHOULD BE IN THE UPPER 20S TO LOW 30S SUGGESTING MOST OF
THE SNOW WILL HAVE A DIFFICULT TIME ACCUMULATING ON ROADS. THE
OTHER AREA OF CONCERN WILL BE REDUCED VISIBILITIES. MODELS ARE
SHOWING A NARROW BAND OF FGEN WITH GOOD VERTICAL CONTINUITY AND ON
THE GRADIENT OF STEEPER MID LEVEL LAPSE RATES SUGGESTING A NARROW
BAND OF ENHANCED SNOWFALL RATES. IT ALSO APPEARS THAT THE THERMAL
PROFILES WILL SUPPORT DENDRITIC FLAKES DURING THE PERIOD OF ENHANCED
FORCING. IF THESE CONDITIONS VERIFY THEN VISIBILITIES DROPPING TO A
HALF MILE OR LESS WILL BE POSSIBLE AT TIMES MONDAY MORNING.
THE ACCUMULATING SNOW WILL END BY NOON IN THE NORTHEAST AS THE
BETTER FORCING MOVES EAST OF THE AREA. COLDER AIR AND STRONGER WINDS
MOVE IN DURING THE AFTERNOON CAUSING FALLING TEMPERATURES DURING THE
MID TO LATE AFTERNOON OVER THE NORTHWEST COUNTIES. THE BRISK
CONDITIONS WILL CONTINUE OVER NIGHT AS A SURFACE LOW MOVES THROUGH
THE WESTERN GREAT LAKES AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
MID/LOWER MISSOURI VALLEY. LOWS TUESDAY MORNING ARE EXPECTED TO
RANGE FROM AROUND 10 IN THE NORTH TO THE MID 20S SOUTH.
THE REST OF THE WEEK LOOKS COLD AND DRY WITH NORTHWEST FLOW
REMAINING OVER THE AREA BETWEEN A BROAD EASTERN US TROF AND RIDGING
OVER THE WESTERN U.S./EASTERN PACIFIC. A REINFORCING SHOT OF COLD
AIR IS PROGGED TO MOVE INTO THE REGION TUESDAY NIGHT RESULTING IN
SINGLE DIGIT LOWS NORTH AND AROUND 20 IN THE SOUTH WEDNESDAY MORNING
AND HIGHS WEDNESDAY IN THE LOW TO MID 20S NORTH TO MID 30S SOUTH.
AFTER WEDNESDAY TEMPERATURES WILL MODERATE A LITTLE WITH HIGHS
EXPECTED TO BE IN THE 30S TO LOW 40S AND LOWS IN THE 20S BY FRIDAY
AND SATURDAY. BUT THESE TEMPERATURES ARE STILL WELL BELOW NORMAL AS
WE APPROACH THE LAST WEEK OF MARCH.
DLF
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 633 AM CDT SUN MAR 17 2013
EXPECT MVFR LEVEL STRATUS OF BKN TO OVC COVERAGE TO INCREASE BACK
OVER ALL OF THE TERMINALS EXCEPT MAYBE DBQ THIS MORNING AS LLVL
FLOW BECOMES MORE EASTERLY. THESE MVFR DECKS TO LINGER INTO EARLY
THIS AFTERNOON BEFORE THEY DIURNALLY RISE UP TO VFR LEVEL DECKS.
GOOD SFC VISIBILITY EXPECTED ALL DAY WITH EAST WINDS OF 10 TO 15
KTS. THEN CIGS MAY LOWER AGAIN TO AT LEAST MVFR LEVELS IN THE VCNTY
OF BRL BY MID EVENING AS SOME LIGHT RAIN OR RAIN MIXED WITH SNOW
DRAWS NEAR FROM THE SOUTH. BUT THE MAIN WEATHER MAKER TONIGHT IN
THE FORM OF A LOW PRESSURE STORM SYSTEM WILL PUSH EASTWARD ACRS
THE NORTHERN PLAINS AND UPPER MS RVR VALLEY. THIS SYSTEM WILL
BRING LIGHT TO MODERATE SNOW AND EVENTUAL IFR CONDITIONS INTO THE
VCNTY OF CID AND THEN DBQ LATE TONIGHT/AFTER 09Z MON MORNING. 12
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...DLF
AVIATION...12
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
335 AM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 335 AM CDT SUN MAR 17 2013
LATEST SFC ANALYSIS WAS INDICATING LARGE AND SEASONABLY STRONG RIDGE
COMPLEX ENGULFING MUCH OF THE UPPER MIDWEST WITH A NEAR 1030 MB
CENTER JUST NORTH OF THE NORTHWEST CORNER ON MN. SOUTHEAST RETURN
FLOW AND SFC PRESSURE GRADIENT TIGHTENING AND ORGANIZING ACRS THE
NORTHWESTERN HIGH PLAINS IN A REGION ALSO BATHED BY ROBUST PRESSURE
FALLS. ALOFT...WATER VAPOR IMAGERY WAS INDICATING A VIGOROUS UPPER
LEVEL WAVE ROLLING IN OFF THE PACIFIC AND ACRS OR/WA ATTM WITH AN
ASSOCIATED BAROCLINIC LEAF PLUME TO THE LEE OF IT ACRS THE WESTERN
ROCKIES. TO THE SOUTH ALONG TIGHTER LLVL BAROCLINIC RIBBON...AN
ISENTROPIC LIFT PRECIP EVENT WAS ONGOING ACRS KS...MO AND INTO
SOUTHERN IL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
TODAY...THE ABOVE MENTIONED STRONG RIDGE OF HIGH PRESSURE WILL LOOK
TO SQUEEZE EASTWARD ACRS THE WESTERN GRT LKS TODAY. AS IT DOES...
IT/S DRYING NORTHEAST TO EASTERLY FETCH IN THE BOUNDARY LAYER OR EVEN
DEEPER SHOULD KEEP MOST OF THE OVERRUNNING PRECIP OFF THE UPGLIDE
PROCESS TO THE SOUTH OF THE CWA. BUT WILL KEEP THE ONGOING MENTION
OF SPRINKLES OR A SLIGHT CHC OF LIGHT RAIN IN THE FAR SOUTH THIS
AFTERNOON. CLOUD COVER AND IT/S EFFECT ON TEMPS THE MAIN CHALLENGE
TODAY. THE RAP SEEMS TO HAVE SOME HANDEL ON CURRENT LLVL STRATUS
TRENDS PUSHING SOUTHWARD. AFTER MUCH OF THESE LOWER CLOUDS PUSH
ALMOST OUT OF THE DVN CWA...THE VEERING NORTHERLY FLOW SUGGESTED
BY THE RAP THEN SLOSHES BACK SOME LOWER LEVEL STRATUS BACK ACRS
MUCH OF THE DVN CWA FROM THE EAST AND NORTHEAST THIS MORNING UNDER
THE ONGOING AND SUBSTANTIAL TRAPPING INVERSION BASED AT H85 TO H75
MB. WITH PLUME OF MID AND UPPER LEVEL CLOUDS STREAMING OFF THE
OVERRUNNING PRECIP AND CONVECTION ACRS KS INTO MO...WITH THE CHANCE
OF THE STRATUS COMING BACK WILL KEEP THE FLAVOR OF THE DAY MOSTLY
CLOUDY ALTHOUGH SOME PEAKS OF SUN AT TIMES PROBABLE NORTH OF I80.
WILL KEEP HIGH TEMPS MAINLY IN THE 30S FOR A CHILLY ST PATRICK/S
DAY...BUT AREAS ALONG AND SOUTH OF I80 MAY GET NEAR 40 WITH SOME
CLOUD THINNING AT TIMES.
TONIGHT...THE DVN CWA TO BE MAINLY IN BETWEEN TWO LIFTING/FORCING
PROCESSES FOR MUCH OF THE NIGHT. THE ABOVE MENTIONED VIGOROUS UPPER
LEVEL WAVE CURRENTLY ACRS THE PACIFIC NORTHWEST WILL CONTINUE TO DIG
ACRS THE NORTHERN PLAINS AND MO RVR VALLEY THROUGH 12Z MON...WITH
UPPER LEVEL TROFFINESS EXTENDING ALL THE WAY DOWN INTO THE
SOUTHEASTERN PLAINS. CONCEPTUALLY THIS SHOULD ALLOW LLVL CYCLOGENESIS
BLOSSOM ACRS THE SOUTHEASTERN PLAINS AN UP THE LOWER TO MID MS RVR
VALLEY. NORTHWESTERN REACHING FLANK OF DEF ZONE PRECIP OFF THIS
FEATURE MAY CLIP THE SOUTHERN AND SOUTHEASTERN CWA THIS EVENING AND
INTO THE OVERNIGHT...BUT DRY LOW TO MID LEVELS WILL HAVE TO BE
OVERCOME. WILL KEEP CHC POPS IN THESE AREAS FOR LIGHT RAIN THIS
EVENING...BECOMING MIXED WITH SNOW OR SLEET INTO EARLY MON MORNING
AS EVAPO COOLING PROCESSES HAVE THEIR AFFECT. SFC TEMPS IN THESE
AREAS WILL BE MARGINAL FOR ANY FREEZING RAIN THREAT AND WILL NOT
MENTION. BUT THE MAIN FORCING EVENT IN VIEW OF THE APPROACHING
DIGGING WAVE WILL LOOK TO OCCUR ACRS THE NORTHEASTERN PLAINS INTO MN
AND IA LATER TONIGHT. DEEPENING SFC LOW PRESSURE TO UNDER 1000 MB TO
ROLL OUT OF THE DAKOTAS AND INTO NORTHWESTERN MN BY 12Z MON. THE
TROF ALMOST TAKING A NEG TILT AS IT DOES SUGGESTS A STRONGLY FORCED
EVENT ACRS THE UPPER MS RVR VALLEY REGION. ASSOCIATED PRECIP SWATH
AHEAD OF THIS PROCESS WILL LOOK TO PUSH ACRS IA AND INTO THE WESTERN/
NORTHWESTERN THIRD OF THE DVN CWA AFTER 08Z MON MORNING MAINLY IN
THE FORM OF SNOW. UPWARD VERTICAL VELOCITIES AND THERMODYNAMIC
PROFILES SUGGEST A BURST OF HEAVY WET SNOW POSSIBLE INTO THE FAR
NORTHWESTERN CWA WHERE UP TO AN INCH OF SNOW MAY OCCUR BY 12Z MON
NORTHWEST OF A CEDAR RAPIDS...TO MANCHESTER IA LINE. UP TO A HALF
INCH POSSIBLE ALONG AND NORTHWEST OF AN IOWA CITY...TO DYERSVILLE
LINE. STILL RATHER MILD SFC/GROUND TEMPS TO ACT AS AN ACCUMULATION
INHIBITOR AND PROMOTE COMPACTION AND MELTING EVENTUALLY. BUT SNOW
RATES BEFORE THE SUN RISES MAY STILL OVERCOME THIS FOR A WHILE TO
ALLOW THE POTENTIAL ACCUMS MENTIONED ABOVE. REST OF THE EVENT COVERED
IN DISCUSSION BELOW. ..12..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 17 2013
SNOW AMOUNTS MONDAY MORNING WILL BE THE MAIN CONCERN FOR THE LONG
TERM. AFTER MONDAY NORTHWEST FLOW TO DOMINATE THE REGION KEEPING
COLD AND DRY CONDITIONS OVER THE AREA INTO THE WEEKEND.
A SHORTWAVE OVER THE PACIFIC NORTHWEST EARLY THIS MORNING IS PROGGED
TO MOVE THROUGH THE MID AND UPPER MISSISSIPPI VALLEY MONDAY. THE
S/W WILL DRAG A STRONG COLD FRONT THROUGH THE REGION MONDAY
AFTERNOON AND EVENING WITH VERY COLD TEMPERATURES RUSHING INTO THE
REGION MONDAY AFTERNOON/NIGHT. THE FORECAST MODELS ARE IN GOOD
AGREEMENT IN SPREADING THE SYNOPTIC FORCING AHEAD OF THIS SYSTEM
OVER THE CWFA MONDAY MORNING WITH THE BETTER FORCING CLIPPING THE
NORTHERN COUNTIES. WITH PW/S EXPECTED TO BE AROUND A HALF INCH OR
SO QPF AMOUNTS OF 1 TO 2 TENTHS OF AN INCH LOOK REASONABLE BETWEEN
12Z AND 18Z. H8 TEMPS MONDAY MORNING WILL BE JUST BELOW ZERO
SUPPORTING SNOW RATIOS AROUND 10 TO 1 EARLY MONDAY MORNING WITH
RATIOS INCREASING TO 15 TO 1 BY LATE MORNING AS THE COLDER AIR
REACHES THE AREA. THE EXPECTED QPF AND SNOW RATIOS SUPPORT SNOWFALL
AMOUNTS IN THE 1 TO 2 INCH RANGE /STORM TOTAL/ NORTH OF I80 WITH THE
LOWER AMOUNTS NEAR I80 AND THE HIGHER AMOUNTS ALONG THE HIGHWAY 20
CORRIDOR. THE BIGGEST IMPACTS FROM THE SNOW MAY BE THE TIMING AND
LOW VISIBILITIES. THE SNOW WILL IMPACT THE MORNING COMMUTE
ESPECIALLY OVER EAST CENTRAL IOWA BUT SURFACE TEMPERATURES DURING
THE SNOW SHOULD BE IN THE UPPER 20S TO LOW 30S SUGGESTING MOST OF
THE SNOW WILL HAVE A DIFFICULT TIME ACCUMULATING ON ROADS. THE
OTHER AREA OF CONCERN WILL BE REDUCED VISIBILITIES. MODELS ARE
SHOWING A NARROW BAND OF FGEN WITH GOOD VERTICAL CONTINUITY AND ON
THE GRADIENT OF STEEPER MID LEVEL LAPSE RATES SUGGESTING A NARROW
BAND OF ENHANCED SNOWFALL RATES. IT ALSO APPEARS THAT THE THERMAL
PROFILES WILL SUPPORT DENDRITIC FLAKES DURING THE PERIOD OF ENHANCED
FORCING. IF THESE CONDITIONS VERIFY THEN VISIBILITIES DROPPING TO A
HALF MILE OR LESS WILL BE POSSIBLE AT TIMES MONDAY MORNING.
THE ACCUMULATING SNOW WILL END BY NOON IN THE NORTHEAST AS THE
BETTER FORCING MOVES EAST OF THE AREA. COLDER AIR AND STRONGER WINDS
MOVE IN DURING THE AFTERNOON CAUSING FALLING TEMPERATURES DURING THE
MID TO LATE AFTERNOON OVER THE NORTHWEST COUNTIES. THE BRISK
CONDITIONS WILL CONTINUE OVER NIGHT AS A SURFACE LOW MOVES THROUGH
THE WESTERN GREAT LAKES AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
MID/LOWER MISSOURI VALLEY. LOWS TUESDAY MORNING ARE EXPECTED TO
RANGE FROM AROUND 10 IN THE NORTH TO THE MID 20S SOUTH.
THE REST OF THE WEEK LOOKS COLD AND DRY WITH NORTHWEST FLOW
REMAINING OVER THE AREA BETWEEN A BROAD EASTERN US TROF AND RIDGING
OVER THE WESTERN U.S./EASTERN PACIFIC. A REINFORCING SHOT OF COLD
AIR IS PROGGED TO MOVE INTO THE REGION TUESDAY NIGHT RESULTING IN
SINGLE DIGIT LOWS NORTH AND AROUND 20 IN THE SOUTH WEDNESDAY MORNING
AND HIGHS WEDNESDAY IN THE LOW TO MID 20S NORTH TO MID 30S SOUTH.
AFTER WEDNESDAY TEMPERATURES WILL MODERATE A LITTLE WITH HIGHS
EXPECTED TO BE IN THE 30S TO LOW 40S AND LOWS IN THE 20S BY FRIDAY
AND SATURDAY. BUT THESE TEMPERATURES ARE STILL WELL BELOW NORMAL AS
WE APPROACH THE LAST WEEK OF MARCH.
DLF
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
A STORM SYSTEM MOVE THROUGH MISSOURI WILL BRING PERSISTENT MVFR
CIGS TO THE REGION THROUGH SUNDAY EVENING. CIGS OF 1800 TO 3000 FT
WILL BE WIDESPREAD. THERE WILL BE A BREAK IN THE STRATUS THROUGH
MID TO LATE MORNING OVER PORTIONS OF EASTERN IOWA...BUT AS WINDS
ALOFT TURN TO THE EAST...THE STRATUS SHOULD FLOW BACK INTO ALL OF
EASTERN IOWA BY 16 T0 18Z SUNDAY. ANY OTHER BREAKS ARE IMPOSSIBLE
TO PREDICT WELL IN ADVANCE...AND WILL BE HANDLED WITH UPDATES AS
NECESSARY. OTHERWISE...NORTH WINDS WILL GRADUALLY TURN TO EAST
OVERNIGHT...AND SHOULD REMAIN AROUND 8 TO 12 KTS THROUGH THE
PERIOD. EAST WINDS ARE EXPECTED THROUGHOUT THE DAY SUNDAY AND
SUNDAY EVENING. DRY CONDITIONS ARE ANTICIPATED...WITH VISIBILITY 6
MILES OR BETTER. AFTER 06Z MONDAY...AREAS OF SNOW ARE LIKELY OVER
THE AREA AS ANOTHER STORM MOVES EAST. ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...DLF
AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1251 PM CDT SUN MAR 17 2013
...UPDATE TO AVIATION...
.DISCUSSION...
A MIX OF PRECIPITATION WAS OCCURRING ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS NORTH OF INTERSTATE 70 AT 08Z. A MIX OF
RAIN...SLEET AND SNOW HAS BEEN OBSERVED. EXPECT THIS PRECIPITATION
TO MOVE OUT OF THE AREA LATER THIS MORNING. RUC AND SREF SUGGEST
SOME REDEVELOPMENT OF PRECIPITATION IN CENTRAL KANSAS LATER THIS
AFTERNOON AS SHORTWAVE MOVES OUT OF THE ROCKIES. COULD SEE SOME
LIGHT RAIN APPROACHING NORTH CENTRAL KANSAS BY EVENING. ACROSS THE
EAST CENTRAL THIS MORNING WILL SEE THE BEST CHANCES OF PRECIPITATION
SOUTH OF I-35 IN ZONE OF FRONTOGENESIS FROM SOUTH CENTRAL INTO EAST
CENTRAL KANSAS. THERMAL PROFILES WOULD SUGGEST THAT THIS
PRECIPITATION WILL BE ALL LIQUID. TEMPERATURES TODAY WILL ONLY RISE
INTO THE LOWER 40S FOR HIGHS.
SATELLITE WAS SHOWING AN UPPER LEVEL TROUGH MOVING ACROSS THE
PACIFIC NORTHWEST AND THIS SYSTEM WILL DEEPEN AND MOVE ACROSS THE
ROCKIES AND INTO THE NORTHERN AND CENTRAL PLAINS TONIGHT. FORCING
WILL BE MAXIMIZED TO THE NORTH OF THE NEBRASKA BORDER TONIGHT AS THE
PV ANOMALY MOVES ACROSS THE NORTHERN PLAINS...SO EXPECTING ONLY 30
TO 40 PERCENT CHANCES OF PRECIPITATION TONIGHT WITH LITTLE IN THE
WAY OF QPF. THERMAL PROFILES SUGGEST THAT PRECIPITATION WILL BE ALL
RAIN THIS EVENING THEN A MIX OF RAIN AND SNOW NORTH OF HIGHWAY 56
AND RAIN SOUTH. LOWS TONIGHT COOLING INTO THE LOWER TO MID 30S. THE
UPPER TROUGH AXIS SHOULD MOVE OUT OF EASTERN KANSAS TOWARD SUNRISE
MONDAY.
A DRY PERIOD IS EXPECTED FROM MONDAY THROUGH WEDNESDAY WITH A DRY
NORTHWEST FLOW. NEXT SHOT OF PRECIPITATION OCCURS THURSDAY THROUGH
FRIDAY AS WAA INCREASE ALONG WITH ISENTROPIC LIFT AHEAD OF AN
APPROACHING UPPER TROUGH. MODELS ALSO SUGGEST THAT PIECES OF ENERGY
WILL MOVE OUT OF THE ROCKIES ACROSS KANSAS DURING THIS PERIOD. THE
ECMWF IS COOLER WITH THE THERMAL PROFILES AND FORECAST SOUNDINGS
SUGGEST THAT IT WILL BE COLD ENOUGH FOR SNOW AND ALSO A RAIN AND
SNOW MIX. THIS STILL MAY CHANGE WITH LATER RUNS. THE SYSTEM MOVES
OUT LATE FRIDAY WITH DRY WEATHER FOR THE START OF THE WEEKEND.
53
&&
.AVIATION...
MVFR STRATUS EXPECTED TO STICK AROUND FOR REMAINDER OF THE DAY AT
ALL TERMINALS. CIGS WILL LIKELY COME DOWN OVERNIGHT TO IFR LEVELS
WITH PERHAPS A PERIOD OF REDUCED VISIBILITY DUE TO HAZE OR PERHAPS
SOME DRIZZLE. EXPECT SKIES TO RAPIDLY CLEAR EARLY MONDAY
MORNING...WITH CLEAR SKIES FROM ROUGHLY 12Z THROUGH REST OF TAF
PERIOD MONDAY.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
646 AM CDT SUN MAR 17 2013
...UPDATE TO AVIATION...
.DISCUSSION...
A MIX OF PRECIPITATION WAS OCCURRING ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS NORTH OF INTERSTATE 70 AT 08Z. A MIX OF
RAIN...SLEET AND SNOW HAS BEEN OBSERVED. EXPECT THIS PRECIPITATION
TO MOVE OUT OF THE AREA LATER THIS MORNING. RUC AND SREF SUGGEST
SOME REDEVELOPMENT OF PRECIPITATION IN CENTRAL KANSAS LATER THIS
AFTERNOON AS SHORTWAVE MOVES OUT OF THE ROCKIES. COULD SEE SOME
LIGHT RAIN APPROACHING NORTH CENTRAL KANSAS BY EVENING. ACROSS THE
EAST CENTRAL THIS MORNING WILL SEE THE BEST CHANCES OF PRECIPITATION
SOUTH OF I-35 IN ZONE OF FRONTOGENESIS FROM SOUTH CENTRAL INTO EAST
CENTRAL KANSAS. THERMAL PROFILES WOULD SUGGEST THAT THIS
PRECIPITATION WILL BE ALL LIQUID. TEMPERATURES TODAY WILL ONLY RISE
INTO THE LOWER 40S FOR HIGHS.
SATELLITE WAS SHOWING AN UPPER LEVEL TROUGH MOVING ACROSS THE
PACIFIC NORTHWEST AND THIS SYSTEM WILL DEEPEN AND MOVE ACROSS THE
ROCKIES AND INTO THE NORTHERN AND CENTRAL PLAINS TONIGHT. FORCING
WILL BE MAXIMIZED TO THE NORTH OF THE NEBRASKA BORDER TONIGHT AS THE
PV ANOMALY MOVES ACROSS THE NORTHERN PLAINS...SO EXPECTING ONLY 30
TO 40 PERCENT CHANCES OF PRECIPITATION TONIGHT WITH LITTLE IN THE
WAY OF QPF. THERMAL PROFILES SUGGEST THAT PRECIPITATION WILL BE ALL
RAIN THIS EVENING THEN A MIX OF RAIN AND SNOW NORTH OF HIGHWAY 56
AND RAIN SOUTH. LOWS TONIGHT COOLING INTO THE LOWER TO MID 30S. THE
UPPER TROUGH AXIS SHOULD MOVE OUT OF EASTERN KANSAS TOWARD SUNRISE
MONDAY.
A DRY PERIOD IS EXPECTED FROM MONDAY THROUGH WEDNESDAY WITH A DRY
NORTHWEST FLOW. NEXT SHOT OF PRECIPITATION OCCURS THURSDAY THROUGH
FRIDAY AS WAA INCREASE ALONG WITH ISENTROPIC LIFT AHEAD OF AN
APPROACHING UPPER TROUGH. MODELS ALSO SUGGEST THAT PIECES OF ENERGY
WILL MOVE OUT OF THE ROCKIES ACROSS KANSAS DURING THIS PERIOD. THE
ECMWF IS COOLER WITH THE THERMAL PROFILES AND FORECAST SOUNDINGS
SUGGEST THAT IT WILL BE COLD ENOUGH FOR SNOW AND ALSO A RAIN AND
SNOW MIX. THIS STILL MAY CHANGE WITH LATER RUNS. THE SYSTEM MOVES
OUT LATE FRIDAY WITH DRY WEATHER FOR THE START OF THE WEEKEND.
53
&&
.AVIATION...
CONFIDENCE IN THIS FORECAST IS LOW. AREA OBSERVATIONS SUGGEST KMHK
IS ON THE EDGE OF MVFR CIGS WITH ANOTHER AREA IN SOUTHEAST KANSAS.
MODELS HAVE PERSISTENTLY TRIED TO BRING KTOP AND KFOE INTO MVFR
CIGS BUT THIS HAS NOT OCCURRED. WILL GO WITH PERSISTENCE AT KMHK
AND WAIT UNTIL AFTER 18Z FOR KTOP AND KFOE WHEN BETTER FORCING
ARRIVES...AND BRING ALL TERMINALS INTO IFR CIGS AS THE NEXT SYSTEM
NEARS. LIGHT PRECIP POSSIBLE THROUGH MUCH OF THE DAY WITH SLOWLY
INCREASING CHANCES FOR AN ALL LIQUID TYPE.
65
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
333 AM CDT SUN MAR 17 2013
.DISCUSSION...
A MIX OF PRECIPITATION WAS OCCURRING ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS NORTH OF INTERSTATE 70 AT 08Z. A MIX OF
RAIN...SLEET AND SNOW HAS BEEN OBSERVED. EXPECT THIS PRECIPITATION
TO MOVE OUT OF THE AREA LATER THIS MORNING. RUC AND SREF SUGGEST
SOME REDEVELOPMENT OF PRECIPITATION IN CENTRAL KANSAS LATER THIS
AFTERNOON AS SHORTWAVE MOVES OUT OF THE ROCKIES. COULD SEE SOME
LIGHT RAIN APPROACHING NORTH CENTRAL KANSAS BY EVENING. ACROSS THE
EAST CENTRAL THIS MORNING WILL SEE THE BEST CHANCES OF PRECIPITATION
SOUTH OF I-35 IN ZONE OF FRONTOGENESIS FROM SOUTH CENTRAL INTO EAST
CENTRAL KANSAS. THERMAL PROFILES WOULD SUGGEST THAT THIS
PRECIPITATION WILL BE ALL LIQUID. TEMPERATURES TODAY WILL ONLY RISE
INTO THE LOWER 40S FOR HIGHS.
SATELLITE WAS SHOWING AN UPPER LEVEL TROUGH MOVING ACROSS THE
PACIFIC NORTHWEST AND THIS SYSTEM WILL DEEPEN AND MOVE ACROSS THE
ROCKIES AND INTO THE NORTHERN AND CENTRAL PLAINS TONIGHT. FORCING
WILL BE MAXIMIZED TO THE NORTH OF THE NEBRASKA BORDER TONIGHT AS THE
PV ANOMALY MOVES ACROSS THE NORTHERN PLAINS...SO EXPECTING ONLY 30
TO 40 PERCENT CHANCES OF PRECIPITATION TONIGHT WITH LITTLE IN THE
WAY OF QPF. THERMAL PROFILES SUGGEST THAT PRECIPITATION WILL BE ALL
RAIN THIS EVENING THEN A MIX OF RAIN AND SNOW NORTH OF HIGHWAY 56
AND RAIN SOUTH. LOWS TONIGHT COOLING INTO THE LOWER TO MID 30S. THE
UPPER TROUGH AXIS SHOULD MOVE OUT OF EASTERN KANSAS TOWARD SUNRISE
MONDAY.
A DRY PERIOD IS EXPECTED FROM MONDAY THROUGH WEDNESDAY WITH A DRY
NORTHWEST FLOW. NEXT SHOT OF PRECIPITATION OCCURS THURSDAY THROUGH
FRIDAY AS WAA INCREASE ALONG WITH ISENTROPIC LIFT AHEAD OF AN
APPROACHING UPPER TROUGH. MODELS ALSO SUGGEST THAT PIECES OF ENERGY
WILL MOVE OUT OF THE ROCKIES ACROSS KANSAS DURING THIS PERIOD. THE
ECMWF IS COOLER WITH THE THERMAL PROFILES AND FORECAST SOUNDINGS
SUGGEST THAT IT WILL BE COLD ENOUGH FOR SNOW AND ALSO A RAIN AND
SNOW MIX. THIS STILL MAY CHANGE WITH LATER RUNS. THE SYSTEM MOVES
OUT LATE FRIDAY WITH DRY WEATHER FOR THE START OF THE WEEKEND.
53
&&
.AVIATION...
DRY AIR CONTINUES TO KEEP VFR CONDITIONS AT THE TERMINALS...BUT
ISENTROPIC LIFT WILL SATURATE THE LAYER AGAIN TO MVFR BY
07-08Z TIMEFRAME...THEN RA/SN MIX LIKELY EXPECTED BY 09Z. AS WAVE
MOVES PAST EXPECT THIS PRECIP TO END BY 14Z BUT MVFR CIGS SHOULD
REMAIN THROUGH 06Z/18. WILL KEEP NORTHEAST WINDS THROUGH THE FCST
PERIOD AT 10-15 KTS.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1037 PM EDT MON MAR 18 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 429 PM EDT MON MAR 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW NEG-TILT TROUGH/VIGOROUS
SHORTWAVE OVER ERN IA/SW WI POISED TO LIFT ENE INTO THE GREAT LAKES
AREA TONIGHT. AREA OF SNOW ASSOC WITH THIS FEATURE STRETCHES FROM
WRN LAKE SUPERIOR/SW UPR MI INTO WI AND NRN LAKE MI. FRONTAL
BOUNDARY OVER THE OHIO/TENNESSEE VALLEYS HAS EFFECTIVELY ROBBED THE
BETTER SURGE OF GULF MOISTURE N TO THE UPPER LAKES AHEAD OF WAVE.
PER 12Z RAOBS...PRECIPITABLE WATER VALUES UPWARDS OF 1 INCH ARE
SOUTH OF THE BOUNDARY WHILE VALUES ARE ONE-QUARTER TO ONE-HALF INCH
OVER THE NRN PLAINS...JUST A LITTLE ABOVE NORMAL FOR THIS TIME OF
YEAR. THE ROBBING OF MOISTURE BY THIS SRN WAVE/FRONT WILL WORK TO
KEEP SNOW ACCUMULATIONS IN CHECK DESPITE VIGOROUS DYNAMICS
ASSOCIATED WITH INCREASINGLY NEG-TILT UPR MS VALLEY SHORTWAVE.
MODEL CONSENSUS PCPN AMOUNTS INTO THIS EVENING ARE ROUGHLY 0.2 TO
0.25 INCHES. WITH SNOW RATIOS LIKELY AROUND 15 TO 1...ADVY FOR
GENERAL SNOWFALL OF 3 TO 4 INCHES STILL LOOKS ON TRACK AS THE SNOW
MAY FALL AT HEAVY AT TIMES FOR A WHILE INTO THE EVENING HRS.
SYNOPTIC SNOW WILL DIMINISH TO PATCHY -SN W TO E TONIGHT AS AREA OF
SNOW TIED TO STRONG FORCING AHEAD OF SHORTWAVE DEPARTS. ATTENTION
LATE TONIGHT THEN TURNS TO THE WRN COUNTIES WHERE STRONG NW WINDS
WILL DEVELOP IN THE WAKE OF SFC LOW MOVING ACROSS ERN LAKE SUPERIOR.
THE STRONG NW WINDS WILL ARRIVE OVER GOGEBIC/ONTONAGON COUNTIES
BEFORE REACHING THE KEWEENAW TUE MORNING. DEEP MOISTURE/CONVERGENT
CYCLONIC WNW FLOW...THE ADVECTION OF INCREASINGLY COLDER 8H TEMPS
ACROSS WRN LAKE SUPERIOR AND A DEEP DGZ SUGGEST VERY HVY LAKE
ENHANCED SNOW WILL LIKELY DEVELOP FROM KIWD N THRU THE KEWEENAW BY
DAYBREAK. COULD EASILY SEE SNOWFALL RATES OF 1-3IN/HR INTO TUESDAY
ACROSS THE HIGHER TERRAIN OF THE W. BLSN WILL ALSO BECOME AN
INCREASING HAZARD AS NW WINDS WILL GUST OVER 30MPH TO AS HIGH AS
40MPH...ESPECIALLY IN OPEN AREAS NEAR LAKE SUPERIOR. WHITE-OUTS WILL
BE A GOOD POSSIBILITY DUE TO COMBINATION OF HVY SNOW/BLSN INTO TUESDAY.
ERN COUNTIES WILL NOT GET INTO THE LAKE ENHANCED SNOW UNTIL WINDS
SHIFT FROM WEST TO NORTHWEST BEHIND COLD FROPA. AS 8H TEMPS SLOWLY
FALL TO AROUND -12 TO -13C OVER ERN LAKE SUPERIOR BY 00Z
WED...EXPECT LAKE ENHANCED SNOW TO GET GOING OVER ERN ALGER...NRN
SCHOOLCRAFT AND LUCE COUNTIES IN CYCLONIC WNW FLOW. ALTHOUGH BEST
MODEL OMEGA INITIALLY MAY STAY BLO DGZ RESULTING IN LOWER SNOW WATER
RATIOS...BELIEVE SNOW ACCUMS WILL INCREASE LATER IN THE DAY ON TUE
AND ESPECIALLY LATE TUE NIGHT AND WED AS COLDER 8H TEMPS CONTINUES TO
SEEP ACROSS ERN LAKE SUPERIOR AND LOW-LVL CONVERGENCE INCREASES WITH
FLOW VEERING NW. NW WINDS INCREASING TO 25-30 MPH...ESPECIALLY ALONG
THE LAKE SUPERIOR SHORE WILL ALSO ADD TO BLOWING SNOW AND LOWER
VSBYS TUE AFTERNOON INTO WEDNESDAY.
AS A RESULT OF CONDITIONS BECOMING INCREASINGLY MORE FAVORABLE FOR
ENHANCED SNOW AND BLOWING SNOW TUE AFTERNOON THROUGH WED
NIGHT...HAVE DECIDED TO UPGRADE WINTER STORM WATCH TO WINTER STORM
WARNING FOR ALGER...LUCE AND NRN SCHOOLCRAFT COUNTIES FOR LATE TUE
MORNING THROUGH WED NIGHT.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 429 PM EDT MON MAR 18 2013
ACTIVE LAKE EFFECT PERIOD FOR NORTHWESTERLY SNOW BELTS WILL CONTINUE
TUESDAY NIGHT INTO EARLY THURSDAY. AS UPPER LOW CLOSES OFF JUST EAST
OF THE AREA AND CYCLONIC FLOW COMBINES WITH H85 TEMPS IN THE -16 TO
-18 RANGE MODERATE TO HEAVY LAKE EFFECT SNOWS WILL CONTINUE. WINDS
WILL CONTINUE TO GUST OVER 35 MPH ESPECIALLY NEAR THE LAKESHORE
THROUGH THE DAY WEDNESDAY INTO WEDNESDAY NIGHT. WILL MAINTAIN THE
LONG DURATION WINTER STORM WARNING ACROSS THE WEST AND KEWEENAW
THROUGH THE DAY WEDNESDAY AND THE EAST INTO THURSDAY MORNING. LAKE
EFFECT SNOW TOTALS IN THE 12 TO 18 INCH RANGE SEEM LIKELY THROUGH
THE TUESDAY TO THURSDAY PERIOD.
LOW LEVEL WINDS BEGIN TO BECOME MORE NORTHERLY ON THURSDAY AS LAKE
EFFECT CONDITIONS BEGIN TO BECOME LESS FAVORABLE. AS MILDER AIR
WRAPS AROUND THE SLOWLY RETROGRADING UPPER LOW EXPECT 85H TEMPS TO
WARM INTO THE -8 TO -10 RANGE AS INVERSION LOWERS. THIS SHOULD
EFFECTIVELY END THE LAKE EFFECT BY LATE THURSDAY INTO EARLY FRIDAY.
OVERALL TREND INTO THE UPCOMING WEEKEND SHOULD FAVOR GENERALLY
TRANQUIL WEATHER WITH TEMPERATURES WITHIN A FEW DEGREES OF NORMAL.
MODELS OFFER SOME MINOR VARIATIONS WITH UPPER LOW DEPARTING THE
AREA AND UPPER PATTERN TRANSITIONING TO A MORE ZONAL FLOW WITH THE
MAIN STORM TRACK SOUTH OF THE AREA...FOR NOW WILL MAINTAIN A
CONSENSUS BLEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 1036 PM EDT MON MAR 18 2013
AS THE LOW PRES TROUGH LIFTS TO THE NORTHEAST OF UPPER MI...SNOW
SHOULD DIMINISH FOR A WHILE TONIGHT AND MAY ALLOW CONDITIONS TO
IMPROVE TO MVFR ESPECIALLY AT SAW AND IWD. LATE TONIGHT...STRONG NW
WINDS BEHIND THE LOW WILL BRING MDT/HVY LAKE ENHANCED SNOW TO
KIWD/KCMX WITH CONDITIONS LIKELY FALLING TO LIFR. HOWEVER...MAINLY
MVFR CONDITIONS ARE EXPECTED AT SAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 PM EDT MON MAR 18 2013
TIGHT PRES GRADIENT AHEAD OF THE LOW OVER NW MN WILL CONTINUE SE WINDS
UP TO 30KT TODAY. GALES WILL LIKELY OCCUR TOWARD MID LAKE PORTIONS
OF NCNTRL AND ERN LAKE SUPERIOR...IN PARTICULAR FROM AROUND
WHITEFISH PT NW TOWARD PASSAGE ISLAND. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE TONIGHT/TUE. THE
GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE. WINDS
WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU. THE
COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO PERIODS
OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER WEATHER ADVISORY UNTIL 5 AM EDT TUESDAY FOR MIZ006-007-
014-085.
WINTER STORM WARNING FROM 11 AM TUESDAY TO 8 AM EDT THURSDAY FOR
MIZ006-007-085.
WINTER WEATHER ADVISORY UNTIL 2 AM EDT /1 AM CDT/ TUESDAY FOR
MIZ005-010>013.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 2 PM TUESDAY TO 8 PM EDT
THURSDAY FOR LSZ243>245-248>251-264>267.
GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR LSZ264-266-267.
GALE WARNING FROM 2 PM TUESDAY TO 2 PM EDT WEDNESDAY FOR
LSZ243>251-265.
HEAVY FREEZING SPRAY WARNING FROM 5 AM EDT /4 AM CDT/ TUESDAY TO
8 AM EDT /7 AM CDT/ THURSDAY FOR LSZ162-240>242-263.
GALE WARNING FROM 8 AM EDT /7 AM CDT/ TUESDAY TO 2 PM EDT /1 PM
CDT/ WEDNESDAY FOR LSZ162-240>242-263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...MZ
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
159 PM EDT SUN MAR 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 526 AM EDT SUN MAR 17 2013
LATEST GFS ANALYSIS SHOWS HIGH LATITUDE POSITIVE HEIGHT ANOMALIES
OVER GREENLAND AND N OF ALASKA WITH A W-E ELONGATED POLAR VORTEX TO
THE S DOMINATING MUCH OF CANADA. CENTER OF VORTEX WAS OVER HUDSON
BAY. SHORTWAVE TROF EXTENDING FROM THE CENTER HAS SWEPT E OF THE
UPPER GREAT LAKES DURING THE NIGHT. IN THE WAKE OF THE WAVE...850MB
TEMP WAS -23C ON 00Z KINL RAOB...AND LATEST RUC ANALYSIS SHOWS 850MB
TEMPS AROUND -20C OVER LAKE SUPERIOR. DESPITE STRONG OVERWATER
INSTABILITY...LES HAS BEEN POORLY ORGANIZED (NO REAL BANDING) AND
GENERALLY LIGHT TO PERHAPS ONLY MDT INTENSITY AT TIMES DESPITE DGZ
DOMINATING CONVECTIVE LAYER AND DESPITE KMQT VAD WIND PROFILE
SHOWING CLOUD TOPS TO 6-7KFT MSL AND NEARLY UNIDIRECTIONAL FLOW THRU
CLOUD DEPTH. DRY ADIABATIC LAPSE RATES BELOW INVERSION PER UPSTREAM
00Z KINL/CWPL SOUNDINGS IS PROBABLY A CONTRIBUTOR TO THE POOR
ORGANIZATION AS IS INFLUX OF DRIER AIR. GIVEN THE LACK OF
ORGANIZATION AND WEAK INTENSITY OF LES...OPTED TO CANCEL LES ADVY
NEAR LAKE SUPERIOR OVER THE E.
SFC HIGH PRES OVER NRN MN WILL QUICKLY MOVE ACROSS THE FCST AREA
TODAY. IN FACT...CENTER SHOULD BE OF THE AREA BY LATE AFTN. AS A
RESULT...ONGOING DIMINISHING LES WILL END W TO E AS NW WINDS BECOME
LIGHT/VRBL THEN SOUTHERLY AFTER SFC HIGH PASSES. MAY SEE AN
ADDITIONAL INCH OF FLUFFY SNOW E OF MARQUETTE IN THE MORNING BEFORE
THE LES ENDS. OTHERWISE...SKIES SHOULD TURN MOSTLY SUNNY W-E AFTER
WIND SHIFT TO THE S FOLLOWING PASSAGE OF THE SFC HIGH PRES. THE DAY
WILL PROBABLY BEGIN MOSTLY SUNNY OVER THE SCNTRL WHERE DOWNSLOPING
IS ALREADY LEADING TO MOSTLY CLEAR SKIES. DESPITE INCREASING
SUNSHINE...HIGH TEMPS WILL ONLY REACH INTO THE 20S WITH 850MB TEMPS
RECOVERING TO -8C TO -12C IN THE AFTN.
DRY WEATHER WILL CONTINUE TONIGHT. HIGH AND THEN MID CLOUDS WILL BE
ON THE INCREASE AHEAD OF VIGOROUS SHORTWAVE THAT IS NOW MOVING
ACROSS THE PACIFIC NW INTO THE NRN ROCKIES. INCREASING CLOUDS AND
INCREASING SE WINDS WILL KEEP TEMPS FROM FALLING SIGNIFICANTLY. SOME
OF THE TRADITIONAL COLD SPOTS MAY DROP TO AROUND 10F...BUT MOST
AREAS SHOULD SEE MINS IN THE MID/UPPER TEENS WITH A SLIGHT RISING
TREND TO TEMPS LATE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 526 AM EDT SUN MAR 17 2013
PRIMARY FOCUS HAS BEEN AND CONTINUES TO BE UPR TROUGH/LOW PRESSURE
SYSTEM MOVING ACROSS UPPER GREAT LAKES ON MONDAY. IN GENERAL MODELS
INDICATE ADVY SNOW EVENT FOR MUCH OF CWA...BUT AT LEAST AS OF THIS
MORNING DOES NOT APPEAR TO BE A BLOCKBUSTER MARCH STORM BY UPPER
LAKES STANDARDS. ONE REASON SYSTEM IS NOT AS STRONG AS IT COULD BE
IS GULF MOISTURE TRYING TO SURGE NORTHWARD IS INTERCEPTED BY SMALLER
AREA OF SFC-H85 LOW PRESSURE SLIDING FROM SOUTHERN PLAINS INTO OHIO
VALLEY. PWATS INTO THAT AREA ARE WELL OVR 200 PCT OF NORMAL WHILE
THEY STAY ONLY AROUND NORMAL INTO WISCONSIN AND UPR MICHIGAN. SECOND
REASON LARGER SCALE SYSTEM IMPACTING AREA ON MONDAY IS NOT AS STRONG
IS DUE TO LIMITED JET ENHANCEMENT/DEEPENING OF H5 LEVEL LOW AS IT
SLIDES ACROSS UPR LAKES REGION. LAST COUPLE RUNS OF GFS/GEM-NH HAVE
TRENDED A BIT DEEPER WITH SFC-H85 LOWS THOUGH AND THIS RESULTS IN A
WETTER TREND FM THE GFS...WITH 12HR QPF OF 0.25-0.30 INCH OVR MOST
OF WEST HALF OF CWA 18Z MONDAY THROUGH 06Z TUESDAY. LARGE SCALE
ENHANCEMENT FACTORS TO BOOST PRECIP ARE MINOR AS NAM/GFS INDICATE
BRIEF PERIOD OF MOISTURE ADVECTION 850-800MB WITH MINIMAL TEMP
ADVECTION IN THAT LAYER. ALSO THERE IS NO JET SUPPORT AND MINIMAL
FRONTOGENESIS SINCE TEMPERATURE GRADIENT SFC-H85 IS LACKING.
THUS...APPERS THAT MOISTURE ADVECTION AND INCREASING CYCLONIC FLOW
AROUND SFC-H85 LOWS WILL DRIVE THE SNOW. EXPECT MOST SNOW TO OCCUR
THROUGH 00Z TUESDAY OVR SW TIER AND 18-21Z MONDAY THROUGH 03Z
TUESDAY IN THE NORTH AND EAST CWA. CONSENSUS OF MODELS FAVOR THAT
TIMING AND THERE IS GOOD AGREEMENT FROM SREF MEMBERS AS WELL. ONE
MESOSCALE EFFECT THAT MAY RESULT IN MORE SNOW IS POSSIBLE LAKE
ENHANCEMENT WITH ESE BLYR WINDS ON THE KEWEENAW AS H85 TEMPS ARE AT
OR COLDER THAN -8C. SHOWED ENHANCED QPF/SNOW FOR KEWEENAW ON MONDAY
AFTN/EVENING TO ACCOUNT FOR THIS. SLR/S FOR THIS EVENT WILL NOT BE TOO
OFF FROM 16:1 CLIMATOLOGY MARK...IF ANYTHING MAY BE SLIGHTLY LOWER
BUT STILL ABOVE 10:1. OVERALL 3"/12HR SEEMS PROBABLE OVER MUCH OF THE
AREA WHICH IS ADVY CRITERIA. MAYBE MORE SNOW OVER FAR WEST AND ACROSS
KEWEENAW PENINUSLA. WPC WWD GRAPHICS INDICATE 4-6 INCHES FOR THOSE
AREAS...WHICH ACTUALLY LINES UP WELL WITH CURRENT FORECAST THINKING.
SINCE BULK OF SNOW OCCURS LATER IN THE 3RD PERIOD...WILL NOT ISSUE
ANY ADVISORIES FOR SYSTEM SNOW ON MONDAY YET.
LK EFFECT INCREASES ON MONDAY NIGHT INTO TUESDAY FOR AREAS FAVORED
BY WNW-NW FLOW. A MAJORITY OF SNOW FROM THE SYSTEM WILL LIKELY COME
DURING THAT TIME AND ADDITIONAL HEADLINES MAY BE NEEDED INTO
TUESDAY. NAM SOUNDINGS INDICATE DEPTH OF LK EFFECT CONVECTIVE LAYER
BUILDS THROUGHOUT THE NIGHT WITH EQL PEAKING OVER 10KFT BTWN 09Z-12Z
ON TUESDAY IN THE WESTERN CWA AND AROUND 15Z ON TUESDAY IN THE
NORTHEAST CWA. GFS /WHICH IS PREFERRED BY WPC WITH TIMING OF THE
SYSTEM DUE TO ITS CONSISTENCY/ SHOWS SIMILAR SETUP BUT IS SLIGHTLY
SLOWER WITH TIMING. SINCE SOUNDINGS INDICATE MAJORITY OF LK
CONVECTIVE LAYER WITHIN THE DGZ...SLR/S WILL PUSH WELL OVER 20:1.
STRONG WINDS OVER 25 KTS IN THE BLYR WILL CUT SLR/S DOWN SLIGHTLY
THOUGH. HIGH SLR/S WITH PERSISTENT CONVERGENCE AND MORE THAN AMPLE
OVER-WATER INSTABILITY WILL RESULT IN AT LEAST MODERATE LK EFFECT
SNOWS FOR FAVORED AREAS. HINT AT REINFORCING SHOT OF COLDER AIR
LATER TUESDAY NIGHT SO AFTER SLIGHT DIMINISHING TREND INTO TUESDAY
EVENING MAY SEE ANOTHER UPTICK IN LK EFFECT AS THE TROUGH AND COLDER
AIR ARRIVE.
STEADY STATE LK EFFECT SETUP CONTINUES INTO WEDNESDAY NIGHT AND
KEPT CATEGORICAL POPS GOING FOR NW FLOW AREAS. SEVERAL INCHES OF
FLUFFY LK EFFECT SNOW SHOULD ACCUMULATE WEDNESDAY AND WEDNESDAY
NIGHT. ACCUMS IN SOME AREAS LIKELY WILL EXCEED A FOOT IN THE 48 HOUR
TIME FRAME TUESDAY THROUGH WEDNESDAY. OTHER HAZARD WILL BE BLOWING
SNOW AND REDUCED VSBY OVER MUCH OF THE EASTERN CWA AS NW WINDS GUST
OVER 25 KTS THROUGH WEDNESDAY. OCCASIONAL WHITEOUTS SEEM LIKELY...
ESPECIALLY ALONG LK SUPERIOR TUESDAY AFTN THROUGH WEDNESDAY MORNING.
WILL CONTINUE TO MENTION THE PROLONGED PERIOD OF MODERATE-HEAVY LK
EFFECT SNOW AND CONSIDERABLE BLSN IN THE HAZARDOUS WEATHER OUTLOOK.
OUR BACKLOADED WINTER JUST WILL NOT LET GO. LK EFFECT GRADUALLY
DIMINISHES INTO THURSDAY AS LOW PRESSURE TROUGH OVER THE REGION
BEGINS TO RELAX. PROBABLY CAN NOT COUNT OUT LGT LK EFFECT OR FLURRIES
INTO AT LEAST FIRST PART OF NEXT WEEKEND THOUGH AS ECMWF/GFS SHOW
WEAK ONSHORE WINDS CONTINUING BTWN HIGH PRESSURE OVER SCNTRL CANADA
AND TROUGHING OVER EASTERN CANADA/NEW ENGLAND. AFTER TEMPS NEAR 30
DEGREES ON MONDAY AHEAD OF DEVELOPING LOW PRESSURE SYSTEM...DAYTIME
TEMPS FOR THE REST OF THE WEEK WILL BE BLO NORMAL. ONLY GRADUAL
WARMING INTO 30S FOR NEXT WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 156 PM EDT SUN MAR 17 2013
WITH SFC HIGH PRES IN CONTROL...DRY LOW-LEVELS WILL CONTINUE KEEPING
VFR CONDITIONS GOING TONIGHT. HOWEVER...UPSLOPE SSE FLOW OFF LAKE
MI COULD RESULT IN MVFR CIGS REDEVELOPING AT KSAW. WILL BE SOMETHING
TO MONITOR INTO THE EVENING HRS TONIGHT. OTHERWISE...TIGHTENING PRES
GRADIENT AND NOCTURNAL INVERSION WILL LIKELY LEAD TO LLWS AT ALL 3
SITES TONIGHT. INCREASING MOISTURE AHEAD OF APPROACHING FRONTAL
SYSTEM WILL CAUSE CIGS TO LOWER BY LATE MON MORNING AT KIWD AND KSAW
AND BY EARLY AFTERNOON AT KCMX. LOOK FOR MVFR CIGS AT BOTH KIWD AND
KSAW BY LATE MON MORNING WITH THE ONSET OF LIGHT SNOW RESTRICTING
VSBY TO MVFR AT KIWD AND THEN MVFR CONDITIONS IN LIGHT SNOW WILL
REACH KCMX BY EARLY MON AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 526 AM EDT SUN MAR 17 2013
WITH HIGH PRES QUICKLY MOVING ACROSS LAKE SUPERIOR TODAY...EXPECT A
PERIOD OF LIGHT WINDS UNDER 15KT. THE DIMINISHING WINDS/WAVES WILL
BRING AN END TO HVY FREEZING SPRAY EARLY THIS MORNING. AS THE HIGH
CONTINUES E...REACHING NEW ENGLAND MON...LOW PRES EMERGING OVER THE
WRN DAKOTAS THIS AFTN WILL TRACK E...REACHING THE UPPER GREAT LAKES
MON NIGHT. TIGHT PRES GRADIENT BTWN THE DEPARTING HIGH AND
APPROACHING LOW WILL BRING SE WINDS UP TO 30KT TONIGHT AND MON. SOME
GALE FORCE GUSTS TO 35KT WILL BE POSSIBLE LATE TONIGHT/MON OVER
PORTIONS OF NCNTRL AND ERN LAKE SUPERIOR. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE MON NIGHT/TUE.
THE GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE.
WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU.
THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO
PERIODS OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
741 AM EDT SUN MAR 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 526 AM EDT SUN MAR 17 2013
LATEST GFS ANALYSIS SHOWS HIGH LATITUDE POSITIVE HEIGHT ANOMALIES
OVER GREENLAND AND N OF ALASKA WITH A W-E ELONGATED POLAR VORTEX TO
THE S DOMINATING MUCH OF CANADA. CENTER OF VORTEX WAS OVER HUDSON
BAY. SHORTWAVE TROF EXTENDING FROM THE CENTER HAS SWEPT E OF THE
UPPER GREAT LAKES DURING THE NIGHT. IN THE WAKE OF THE WAVE...850MB
TEMP WAS -23C ON 00Z KINL RAOB...AND LATEST RUC ANALYSIS SHOWS 850MB
TEMPS AROUND -20C OVER LAKE SUPERIOR. DESPITE STRONG OVERWATER
INSTABILITY...LES HAS BEEN POORLY ORGANIZED (NO REAL BANDING) AND
GENERALLY LIGHT TO PERHAPS ONLY MDT INTENSITY AT TIMES DESPITE DGZ
DOMINATING CONVECTIVE LAYER AND DESPITE KMQT VAD WIND PROFILE
SHOWING CLOUD TOPS TO 6-7KFT MSL AND NEARLY UNIDIRECTIONAL FLOW THRU
CLOUD DEPTH. DRY ADIABATIC LAPSE RATES BELOW INVERSION PER UPSTREAM
00Z KINL/CWPL SOUNDINGS IS PROBABLY A CONTRIBUTOR TO THE POOR
ORGANIZATION AS IS INFLUX OF DRIER AIR. GIVEN THE LACK OF
ORGANIZATION AND WEAK INTENSITY OF LES...OPTED TO CANCEL LES ADVY
NEAR LAKE SUPERIOR OVER THE E.
SFC HIGH PRES OVER NRN MN WILL QUICKLY MOVE ACROSS THE FCST AREA
TODAY. IN FACT...CENTER SHOULD BE OF THE AREA BY LATE AFTN. AS A
RESULT...ONGOING DIMINISHING LES WILL END W TO E AS NW WINDS BECOME
LIGHT/VRBL THEN SOUTHERLY AFTER SFC HIGH PASSES. MAY SEE AN
ADDITIONAL INCH OF FLUFFY SNOW E OF MARQUETTE IN THE MORNING BEFORE
THE LES ENDS. OTHERWISE...SKIES SHOULD TURN MOSTLY SUNNY W-E AFTER
WIND SHIFT TO THE S FOLLOWING PASSAGE OF THE SFC HIGH PRES. THE DAY
WILL PROBABLY BEGIN MOSTLY SUNNY OVER THE SCNTRL WHERE DOWNSLOPING
IS ALREADY LEADING TO MOSTLY CLEAR SKIES. DESPITE INCREASING
SUNSHINE...HIGH TEMPS WILL ONLY REACH INTO THE 20S WITH 850MB TEMPS
RECOVERING TO -8C TO -12C IN THE AFTN.
DRY WEATHER WILL CONTINUE TONIGHT. HIGH AND THEN MID CLOUDS WILL BE
ON THE INCREASE AHEAD OF VIGOROUS SHORTWAVE THAT IS NOW MOVING
ACROSS THE PACIFIC NW INTO THE NRN ROCKIES. INCREASING CLOUDS AND
INCREASING SE WINDS WILL KEEP TEMPS FROM FALLING SIGNIFICANTLY. SOME
OF THE TRADITIONAL COLD SPOTS MAY DROP TO AROUND 10F...BUT MOST
AREAS SHOULD SEE MINS IN THE MID/UPPER TEENS WITH A SLIGHT RISING
TREND TO TEMPS LATE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 526 AM EDT SUN MAR 17 2013
PRIMARY FOCUS HAS BEEN AND CONTINUES TO BE UPR TROUGH/LOW PRESSURE
SYSTEM MOVING ACROSS UPPER GREAT LAKES ON MONDAY. IN GENERAL MODELS
INDICATE ADVY SNOW EVENT FOR MUCH OF CWA...BUT AT LEAST AS OF THIS
MORNING DOES NOT APPEAR TO BE A BLOCKBUSTER MARCH STORM BY UPPER
LAKES STANDARDS. ONE REASON SYSTEM IS NOT AS STRONG AS IT COULD BE
IS GULF MOISTURE TRYING TO SURGE NORTHWARD IS INTERCEPTED BY SMALLER
AREA OF SFC-H85 LOW PRESSURE SLIDING FROM SOUTHERN PLAINS INTO OHIO
VALLEY. PWATS INTO THAT AREA ARE WELL OVR 200 PCT OF NORMAL WHILE
THEY STAY ONLY AROUND NORMAL INTO WISCONSIN AND UPR MICHIGAN. SECOND
REASON LARGER SCALE SYSTEM IMPACTING AREA ON MONDAY IS NOT AS STRONG
IS DUE TO LIMITED JET ENHANCEMENT/DEEPENING OF H5 LEVEL LOW AS IT
SLIDES ACROSS UPR LAKES REGION. LAST COUPLE RUNS OF GFS/GEM-NH HAVE
TRENDED A BIT DEEPER WITH SFC-H85 LOWS THOUGH AND THIS RESULTS IN A
WETTER TREND FM THE GFS...WITH 12HR QPF OF 0.25-0.30 INCH OVR MOST
OF WEST HALF OF CWA 18Z MONDAY THROUGH 06Z TUESDAY. LARGE SCALE
ENHANCEMENT FACTORS TO BOOST PRECIP ARE MINOR AS NAM/GFS INDICATE
BRIEF PERIOD OF MOISTURE ADVECTION 850-800MB WITH MINIMAL TEMP
ADVECTION IN THAT LAYER. ALSO THERE IS NO JET SUPPORT AND MINIMAL
FRONTOGENESIS SINCE TEMPERATURE GRADIENT SFC-H85 IS LACKING.
THUS...APPERS THAT MOISTURE ADVECTION AND INCREASING CYCLONIC FLOW
AROUND SFC-H85 LOWS WILL DRIVE THE SNOW. EXPECT MOST SNOW TO OCCUR
THROUGH 00Z TUESDAY OVR SW TIER AND 18-21Z MONDAY THROUGH 03Z
TUESDAY IN THE NORTH AND EAST CWA. CONSENSUS OF MODELS FAVOR THAT
TIMING AND THERE IS GOOD AGREEMENT FROM SREF MEMBERS AS WELL. ONE
MESOSCALE EFFECT THAT MAY RESULT IN MORE SNOW IS POSSIBLE LAKE
ENHANCEMENT WITH ESE BLYR WINDS ON THE KEWEENAW AS H85 TEMPS ARE AT
OR COLDER THAN -8C. SHOWED ENHANCED QPF/SNOW FOR KEWEENAW ON MONDAY
AFTN/EVENING TO ACCOUNT FOR THIS. SLR/S FOR THIS EVENT WILL NOT BE TOO
OFF FROM 16:1 CLIMATOLOGY MARK...IF ANYTHING MAY BE SLIGHTLY LOWER
BUT STILL ABOVE 10:1. OVERALL 3"/12HR SEEMS PROBABLE OVER MUCH OF THE
AREA WHICH IS ADVY CRITERIA. MAYBE MORE SNOW OVER FAR WEST AND ACROSS
KEWEENAW PENINUSLA. WPC WWD GRAPHICS INDICATE 4-6 INCHES FOR THOSE
AREAS...WHICH ACTUALLY LINES UP WELL WITH CURRENT FORECAST THINKING.
SINCE BULK OF SNOW OCCURS LATER IN THE 3RD PERIOD...WILL NOT ISSUE
ANY ADVISORIES FOR SYSTEM SNOW ON MONDAY YET.
LK EFFECT INCREASES ON MONDAY NIGHT INTO TUESDAY FOR AREAS FAVORED
BY WNW-NW FLOW. A MAJORITY OF SNOW FROM THE SYSTEM WILL LIKELY COME
DURING THAT TIME AND ADDITIONAL HEADLINES MAY BE NEEDED INTO
TUESDAY. NAM SOUNDINGS INDICATE DEPTH OF LK EFFECT CONVECTIVE LAYER
BUILDS THROUGHOUT THE NIGHT WITH EQL PEAKING OVER 10KFT BTWN 09Z-12Z
ON TUESDAY IN THE WESTERN CWA AND AROUND 15Z ON TUESDAY IN THE
NORTHEAST CWA. GFS /WHICH IS PREFERRED BY WPC WITH TIMING OF THE
SYSTEM DUE TO ITS CONSISTENCY/ SHOWS SIMILAR SETUP BUT IS SLIGHTLY
SLOWER WITH TIMING. SINCE SOUNDINGS INDICATE MAJORITY OF LK
CONVECTIVE LAYER WITHIN THE DGZ...SLR/S WILL PUSH WELL OVER 20:1.
STRONG WINDS OVER 25 KTS IN THE BLYR WILL CUT SLR/S DOWN SLIGHTLY
THOUGH. HIGH SLR/S WITH PERSISTENT CONVERGENCE AND MORE THAN AMPLE
OVER-WATER INSTABILITY WILL RESULT IN AT LEAST MODERATE LK EFFECT
SNOWS FOR FAVORED AREAS. HINT AT REINFORCING SHOT OF COLDER AIR
LATER TUESDAY NIGHT SO AFTER SLIGHT DIMINISHING TREND INTO TUESDAY
EVENING MAY SEE ANOTHER UPTICK IN LK EFFECT AS THE TROUGH AND COLDER
AIR ARRIVE.
STEADY STATE LK EFFECT SETUP CONTINUES INTO WEDNESDAY NIGHT AND
KEPT CATEGORICAL POPS GOING FOR NW FLOW AREAS. SEVERAL INCHES OF
FLUFFY LK EFFECT SNOW SHOULD ACCUMULATE WEDNESDAY AND WEDNESDAY
NIGHT. ACCUMS IN SOME AREAS LIKELY WILL EXCEED A FOOT IN THE 48 HOUR
TIME FRAME TUESDAY THROUGH WEDNESDAY. OTHER HAZARD WILL BE BLOWING
SNOW AND REDUCED VSBY OVER MUCH OF THE EASTERN CWA AS NW WINDS GUST
OVER 25 KTS THROUGH WEDNESDAY. OCCASIONAL WHITEOUTS SEEM LIKELY...
ESPECIALLY ALONG LK SUPERIOR TUESDAY AFTN THROUGH WEDNESDAY MORNING.
WILL CONTINUE TO MENTION THE PROLONGED PERIOD OF MODERATE-HEAVY LK
EFFECT SNOW AND CONSIDERABLE BLSN IN THE HAZARDOUS WEATHER OUTLOOK.
OUR BACKLOADED WINTER JUST WILL NOT LET GO. LK EFFECT GRADUALLY
DIMINISHES INTO THURSDAY AS LOW PRESSURE TROUGH OVER THE REGION
BEGINS TO RELAX. PROBABLY CAN NOT COUNT OUT LGT LK EFFECT OR FLURRIES
INTO AT LEAST FIRST PART OF NEXT WEEKEND THOUGH AS ECMWF/GFS SHOW
WEAK ONSHORE WINDS CONTINUING BTWN HIGH PRESSURE OVER SCNTRL CANADA
AND TROUGHING OVER EASTERN CANADA/NEW ENGLAND. AFTER TEMPS NEAR 30
DEGREES ON MONDAY AHEAD OF DEVELOPING LOW PRESSURE SYSTEM...DAYTIME
TEMPS FOR THE REST OF THE WEEK WILL BE BLO NORMAL. ONLY GRADUAL
WARMING INTO 30S FOR NEXT WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 740 AM EDT SUN MAR 17 2013
HIGH PRES QUICKLY SLIDING ACROSS THE UPPER GREAT LAKES TODAY WILL
BRING AN END TO LINGERING -SHSN/FLURRIES AT KCMX/KSAW THIS MORNING.
IN FACT...WITH WINDS BECOMING S/SE AFTER PASSAGE OF SFC HIGH PRES...
EXPECT STRATOCU (MVFR CIGS HAVE RECENTLY DEVELOPED AT KIWD/KCMX/KSAW
DUE TO FALLING INVERSION) WILL CLEAR OUT FROM W TO E THIS MORNING.
DRY LOW-LEVELS WILL LINGER TONIGHT...RESULTING IN VFR CONDITIONS
CONTINUING. HOWEVER...UPSLOPE SSE FLOW OFF LAKE MI COULD RESULT IN
MVFR CIGS REDEVELOPING AT KSAW. WILL BE SOMETHING TO MONITOR.
OTHERWISE...TIGHTENING PRES GRADIENT AND NOCTURNAL INVERSION WILL
LIKELY LEAD TO LLWS AT ALL 3 SITES TONIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 526 AM EDT SUN MAR 17 2013
WITH HIGH PRES QUICKLY MOVING ACROSS LAKE SUPERIOR TODAY...EXPECT A
PERIOD OF LIGHT WINDS UNDER 15KT. THE DIMINISHING WINDS/WAVES WILL
BRING AN END TO HVY FREEZING SPRAY EARLY THIS MORNING. AS THE HIGH
CONTINUES E...REACHING NEW ENGLAND MON...LOW PRES EMERGING OVER THE
WRN DAKOTAS THIS AFTN WILL TRACK E...REACHING THE UPPER GREAT LAKES
MON NIGHT. TIGHT PRES GRADIENT BTWN THE DEPARTING HIGH AND
APPROACHING LOW WILL BRING SE WINDS UP TO 30KT TONIGHT AND MON. SOME
GALE FORCE GUSTS TO 35KT WILL BE POSSIBLE LATE TONIGHT/MON OVER
PORTIONS OF NCNTRL AND ERN LAKE SUPERIOR. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE MON NIGHT/TUE.
THE GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE.
WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU.
THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO
PERIODS OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 9 AM EDT THIS MORNING FOR
LSZ245-248>251-265>267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
536 AM EDT SUN MAR 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 526 AM EDT SUN MAR 17 2013
LATEST GFS ANALYSIS SHOWS HIGH LATITUDE POSITIVE HEIGHT ANOMALIES
OVER GREENLAND AND N OF ALASKA WITH A W-E ELONGATED POLAR VORTEX TO
THE S DOMINATING MUCH OF CANADA. CENTER OF VORTEX WAS OVER HUDSON
BAY. SHORTWAVE TROF EXTENDING FROM THE CENTER HAS SWEPT E OF THE
UPPER GREAT LAKES DURING THE NIGHT. IN THE WAKE OF THE WAVE...850MB
TEMP WAS -23C ON 00Z KINL RAOB...AND LATEST RUC ANALYSIS SHOWS 850MB
TEMPS AROUND -20C OVER LAKE SUPERIOR. DESPITE STRONG OVERWATER
INSTABILITY...LES HAS BEEN POORLY ORGANIZED (NO REAL BANDING) AND
GENERALLY LIGHT TO PERHAPS ONLY MDT INTENSITY AT TIMES DESPITE DGZ
DOMINATING CONVECTIVE LAYER AND DESPITE KMQT VAD WIND PROFILE
SHOWING CLOUD TOPS TO 6-7KFT MSL AND NEARLY UNIDIRECTIONAL FLOW THRU
CLOUD DEPTH. DRY ADIABATIC LAPSE RATES BELOW INVERSION PER UPSTREAM
00Z KINL/CWPL SOUNDINGS IS PROBABLY A CONTRIBUTOR TO THE POOR
ORGANIZATION AS IS INFLUX OF DRIER AIR. GIVEN THE LACK OF
ORGANIZATION AND WEAK INTENSITY OF LES...OPTED TO CANCEL LES ADVY
NEAR LAKE SUPERIOR OVER THE E.
SFC HIGH PRES OVER NRN MN WILL QUICKLY MOVE ACROSS THE FCST AREA
TODAY. IN FACT...CENTER SHOULD BE OF THE AREA BY LATE AFTN. AS A
RESULT...ONGOING DIMINISHING LES WILL END W TO E AS NW WINDS BECOME
LIGHT/VRBL THEN SOUTHERLY AFTER SFC HIGH PASSES. MAY SEE AN
ADDITIONAL INCH OF FLUFFY SNOW E OF MARQUETTE IN THE MORNING BEFORE
THE LES ENDS. OTHERWISE...SKIES SHOULD TURN MOSTLY SUNNY W-E AFTER
WIND SHIFT TO THE S FOLLOWING PASSAGE OF THE SFC HIGH PRES. THE DAY
WILL PROBABLY BEGIN MOSTLY SUNNY OVER THE SCNTRL WHERE DOWNSLOPING
IS ALREADY LEADING TO MOSTLY CLEAR SKIES. DESPITE INCREASING
SUNSHINE...HIGH TEMPS WILL ONLY REACH INTO THE 20S WITH 850MB TEMPS
RECOVERING TO -8C TO -12C IN THE AFTN.
DRY WEATHER WILL CONTINUE TONIGHT. HIGH AND THEN MID CLOUDS WILL BE
ON THE INCREASE AHEAD OF VIGOROUS SHORTWAVE THAT IS NOW MOVING
ACROSS THE PACIFIC NW INTO THE NRN ROCKIES. INCREASING CLOUDS AND
INCREASING SE WINDS WILL KEEP TEMPS FROM FALLING SIGNIFICANTLY. SOME
OF THE TRADITIONAL COLD SPOTS MAY DROP TO AROUND 10F...BUT MOST
AREAS SHOULD SEE MINS IN THE MID/UPPER TEENS WITH A SLIGHT RISING
TREND TO TEMPS LATE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 526 AM EDT SUN MAR 17 2013
PRIMARY FOCUS HAS BEEN AND CONTINUES TO BE UPR TROUGH/LOW PRESSURE
SYSTEM MOVING ACROSS UPPER GREAT LAKES ON MONDAY. IN GENERAL MODELS
INDICATE ADVY SNOW EVENT FOR MUCH OF CWA...BUT AT LEAST AS OF THIS
MORNING DOES NOT APPEAR TO BE A BLOCKBUSTER MARCH STORM BY UPPER
LAKES STANDARDS. ONE REASON SYSTEM IS NOT AS STRONG AS IT COULD BE
IS GULF MOISTURE TRYING TO SURGE NORTHWARD IS INTERCEPTED BY SMALLER
AREA OF SFC-H85 LOW PRESSURE SLIDING FROM SOUTHERN PLAINS INTO OHIO
VALLEY. PWATS INTO THAT AREA ARE WELL OVR 200 PCT OF NORMAL WHILE
THEY STAY ONLY AROUND NORMAL INTO WISCONSIN AND UPR MICHIGAN. SECOND
REASON LARGER SCALE SYSTEM IMPACTING AREA ON MONDAY IS NOT AS STRONG
IS DUE TO LIMITED JET ENHANCEMENT/DEEPENING OF H5 LEVEL LOW AS IT
SLIDES ACROSS UPR LAKES REGION. LAST COUPLE RUNS OF GFS/GEM-NH HAVE
TRENDED A BIT DEEPER WITH SFC-H85 LOWS THOUGH AND THIS RESULTS IN A
WETTER TREND FM THE GFS...WITH 12HR QPF OF 0.25-0.30 INCH OVR MOST
OF WEST HALF OF CWA 18Z MONDAY THROUGH 06Z TUESDAY. LARGE SCALE
ENHANCEMENT FACTORS TO BOOST PRECIP ARE MINOR AS NAM/GFS INDICATE
BRIEF PERIOD OF MOISTURE ADVECTION 850-800MB WITH MINIMAL TEMP
ADVECTION IN THAT LAYER. ALSO THERE IS NO JET SUPPORT AND MINIMAL
FRONTOGENESIS SINCE TEMPERATURE GRADIENT SFC-H85 IS LACKING.
THUS...APPERS THAT MOISTURE ADVECTION AND INCREASING CYCLONIC FLOW
AROUND SFC-H85 LOWS WILL DRIVE THE SNOW. EXPECT MOST SNOW TO OCCUR
THROUGH 00Z TUESDAY OVR SW TIER AND 18-21Z MONDAY THROUGH 03Z
TUESDAY IN THE NORTH AND EAST CWA. CONSENSUS OF MODELS FAVOR THAT
TIMING AND THERE IS GOOD AGREEMENT FROM SREF MEMBERS AS WELL. ONE
MESOSCALE EFFECT THAT MAY RESULT IN MORE SNOW IS POSSIBLE LAKE
ENHANCEMENT WITH ESE BLYR WINDS ON THE KEWEENAW AS H85 TEMPS ARE AT
OR COLDER THAN -8C. SHOWED ENHANCED QPF/SNOW FOR KEWEENAW ON MONDAY
AFTN/EVENING TO ACCOUNT FOR THIS. SLR/S FOR THIS EVENT WILL NOT BE TOO
OFF FROM 16:1 CLIMATOLOGY MARK...IF ANYTHING MAY BE SLIGHTLY LOWER
BUT STILL ABOVE 10:1. OVERALL 3"/12HR SEEMS PROBABLE OVER MUCH OF THE
AREA WHICH IS ADVY CRITERIA. MAYBE MORE SNOW OVER FAR WEST AND ACROSS
KEWEENAW PENINUSLA. WPC WWD GRAPHICS INDICATE 4-6 INCHES FOR THOSE
AREAS...WHICH ACTUALLY LINES UP WELL WITH CURRENT FORECAST THINKING.
SINCE BULK OF SNOW OCCURS LATER IN THE 3RD PERIOD...WILL NOT ISSUE
ANY ADVISORIES FOR SYSTEM SNOW ON MONDAY YET.
LK EFFECT INCREASES ON MONDAY NIGHT INTO TUESDAY FOR AREAS FAVORED
BY WNW-NW FLOW. A MAJORITY OF SNOW FROM THE SYSTEM WILL LIKELY COME
DURING THAT TIME AND ADDITIONAL HEADLINES MAY BE NEEDED INTO
TUESDAY. NAM SOUNDINGS INDICATE DEPTH OF LK EFFECT CONVECTIVE LAYER
BUILDS THROUGHOUT THE NIGHT WITH EQL PEAKING OVER 10KFT BTWN 09Z-12Z
ON TUESDAY IN THE WESTERN CWA AND AROUND 15Z ON TUESDAY IN THE
NORTHEAST CWA. GFS /WHICH IS PREFERRED BY WPC WITH TIMING OF THE
SYSTEM DUE TO ITS CONSISTENCY/ SHOWS SIMILAR SETUP BUT IS SLIGHTLY
SLOWER WITH TIMING. SINCE SOUNDINGS INDICATE MAJORITY OF LK
CONVECTIVE LAYER WITHIN THE DGZ...SLR/S WILL PUSH WELL OVER 20:1.
STRONG WINDS OVER 25 KTS IN THE BLYR WILL CUT SLR/S DOWN SLIGHTLY
THOUGH. HIGH SLR/S WITH PERSISTENT CONVERGENCE AND MORE THAN AMPLE
OVER-WATER INSTABILITY WILL RESULT IN AT LEAST MODERATE LK EFFECT
SNOWS FOR FAVORED AREAS. HINT AT REINFORCING SHOT OF COLDER AIR
LATER TUESDAY NIGHT SO AFTER SLIGHT DIMINISHING TREND INTO TUESDAY
EVENING MAY SEE ANOTHER UPTICK IN LK EFFECT AS THE TROUGH AND COLDER
AIR ARRIVE.
STEADY STATE LK EFFECT SETUP CONTINUES INTO WEDNESDAY NIGHT AND
KEPT CATEGORICAL POPS GOING FOR NW FLOW AREAS. SEVERAL INCHES OF
FLUFFY LK EFFECT SNOW SHOULD ACCUMULATE WEDNESDAY AND WEDNESDAY
NIGHT. ACCUMS IN SOME AREAS LIKELY WILL EXCEED A FOOT IN THE 48 HOUR
TIME FRAME TUESDAY THROUGH WEDNESDAY. OTHER HAZARD WILL BE BLOWING
SNOW AND REDUCED VSBY OVER MUCH OF THE EASTERN CWA AS NW WINDS GUST
OVER 25 KTS THROUGH WEDNESDAY. OCCASIONAL WHITEOUTS SEEM LIKELY...
ESPECIALLY ALONG LK SUPERIOR TUESDAY AFTN THROUGH WEDNESDAY MORNING.
WILL CONTINUE TO MENTION THE PROLONGED PERIOD OF MODERATE-HEAVY LK
EFFECT SNOW AND CONSIDERABLE BLSN IN THE HAZARDOUS WEATHER OUTLOOK.
OUR BACKLOADED WINTER JUST WILL NOT LET GO. LK EFFECT GRADUALLY
DIMINISHES INTO THURSDAY AS LOW PRESSURE TROUGH OVER THE REGION
BEGINS TO RELAX. PROBABLY CAN NOT COUNT OUT LGT LK EFFECT OR FLURRIES
INTO AT LEAST FIRST PART OF NEXT WEEKEND THOUGH AS ECMWF/GFS SHOW
WEAK ONSHORE WINDS CONTINUING BTWN HIGH PRESSURE OVER SCNTRL CANADA
AND TROUGHING OVER EASTERN CANADA/NEW ENGLAND. AFTER TEMPS NEAR 30
DEGREES ON MONDAY AHEAD OF DEVELOPING LOW PRESSURE SYSTEM...DAYTIME
TEMPS FOR THE REST OF THE WEEK WILL BE BLO NORMAL. ONLY GRADUAL
WARMING INTO 30S FOR NEXT WEEKEND. &&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 140 AM EDT SUN MAR 17 2013
LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO DIMINISH OVERNIGHT AS HIGH
HIGH PRES BUILDS INTO THE REGION WITH SUBSIDENCE AND LOW LEVEL
DIFFLUENT FLOW. HOWEVER...LAKE EFFECT CLOUDS AND FLURRIES SHOULD
STILL LINGER AT CMX INTO THE MORNING BEFORE CLOUDS SCATTER OUT.
OTHERWISE...EXPECT IMPROVEMENT TO VFR CONDITIONS AT SAW OVERNIGHT AND
CONTINUING VFR AT IWD. AS WINDS BECOME VARIABLE AND THEN SOUTHERLY
TODAY...DRY LOW LEVEL LEVEL AIR WILL PERSIST WITH ONLY SCT-BKN HIGH
CLOUDS PREVAILING INTO THE EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 526 AM EDT SUN MAR 17 2013
WITH HIGH PRES QUICKLY MOVING ACROSS LAKE SUPERIOR TODAY...EXPECT A
PERIOD OF LIGHT WINDS UNDER 15KT. THE DIMINISHING WINDS/WAVES WILL
BRING AN END TO HVY FREEZING SPRAY EARLY THIS MORNING. AS THE HIGH
CONTINUES E...REACHING NEW ENGLAND MON...LOW PRES EMERGING OVER THE
WRN DAKOTAS THIS AFTN WILL TRACK E...REACHING THE UPPER GREAT LAKES
MON NIGHT. TIGHT PRES GRADIENT BTWN THE DEPARTING HIGH AND
APPROACHING LOW WILL BRING SE WINDS UP TO 30KT TONIGHT AND MON. SOME
GALE FORCE GUSTS TO 35KT WILL BE POSSIBLE LATE TONIGHT/MON OVER
PORTIONS OF NCNTRL AND ERN LAKE SUPERIOR. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE MON NIGHT/TUE.
THE GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE.
WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU.
THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO
PERIODS OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 9 AM EDT THIS MORNING FOR
LSZ245-248>251-265>267.
HEAVY FREEZING SPRAY WARNING UNTIL 6 AM EDT /5 AM CDT/ EARLY
THIS MORNING FOR LSZ240>244-263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS DULUTH MN
109 PM CDT SUN MAR 17 2013
.AVIATION.../18Z TAF ISSUANCE/
VFR CONDITIONS WILL GRADUALLY GIVE WAY TO THICKENING CLOUDS AND
LOWERING CLOUDS BY THIS EVENING. VFR WILL QUICKLY BECOME MVFR
DURING THE EVENING AND THEN IFR/LIFR OVERNIGHT. CIGS AND VSBYS
WILL DROP RAPIDLY AS THE SNOW SPREADS IN FROM A STORM SYSTEM TO
THE WEST OF OUR AREA.
&&
.PREV DISCUSSION... /ISSUED 1006 AM CDT SUN MAR 17 2013/
UPDATE...
THE FORECAST WAS UPDATED THROUGH TONIGHT. THE MAIN CHANGES
WERE TO SKY COVER. IT APPEARS THE COMBINATION OF BKN/OVC MID/LOW
LEVEL CLOUDS IN WESTERN MINNESOTA MOVING TOWARDS THE
NORTHLAND AND INCREASING LOW LEVEL CLOUDS ACROSS THE EASTERN
FORECAST AREA THIS AFTERNOON WILL RESULT IN A GENERALLY INCREASING
CLOUD COVER TREND THROUGH THE AFTERNOON. THE 12Z NAM12 SOUNDINGS
ARE SHOWING THAT CONVECTIVE TEMPERATURES WILL BE REACHED EARLY
THIS AFTERNOON AND LIKELY RESULT IN AT LEAST SOME SCATTERED LOW
LEVEL CLOUDS ACROSS THE EASTERN FORECAST. THIS SHOWS UP TOO IN
RECENT HRRR MODEL RUNS. ALSO...THERE IS PLENTY OF BKN/OVC MID/LOW
LEVEL CLOUDS MOVING THROUGH WESTERN MINNESOTA AND THE EASTERN
DAKOTAS ON PATH TOWARDS THE NORTHLAND...AND THERE DOES NOT APPEAR
TO BE MUCH TO STOP IT AS THE HIGH PRESSURE OVER THE GREAT LAKES
CONTINUES TO MOVE EAST. RECENT MODEL GUIDANCE WAS ALSO SHOWING
LOWER HIGH TEMPERATURES TODAY...WHICH SHOULD MAKE SOME SENSE
CONSIDERING HOW COLD IT GOT THIS MORNING AND THE INCREASING CLOUD
COVER TODAY. THEREFORE...DECREASED THE HIGHS A BIT. UPDATED THE
PCPN TIMING LATE THIS AFTERNOON AND INTO TONIGHT A BIT...BUT DID
NOT YET CHANGE THE PCPN/SNOWFALL FORECAST. I WILL LOOK MORE INTO
THIS EARLY THIS AFTERNOON. THE NIGHT SHIFT BRIEFED ME ABOUT THE
DIFFERENCES THE MODELS HAVE IN THE TRACK OF THE SURFACE LOW WITH
THE APPROACHING WINTER STORM SYSTEM. THE 00Z/06Z NAM12 STILL HAD A
MUCH MORE NORTHERN TRACK THAN THE OTHER MODELS...BUT I AM HAPPY TO
SEE THAT THE RECENT 12Z NAM12 CAME IN WITH A TRACK MUCH MORE SOUTH
AND SIMILAR TO THE ECMWF AND GFS. HOPEFULLY THE OTHER 12Z MODEL
RUNS WILL FINALLY FIND SOME CONSENSUS...ESPECIALLY THE GEM...WHICH
IS THE OTHER OUTLIER DUE TO ITS MORE SOUTHERN TRACK.
PREV DISCUSSION... /ISSUED 640 AM CDT SUN MAR 17 2013/
AVIATION...12Z TAFS.
VFR UNTIL ABOUT 03Z WHEN MVFR CIGS/VSBYS IN LIGHT SNOW BEGIN TO
SPREAD ACROSS THE TERMINALS FROM W TO E. THIS IS IN RESPONSE TO
THE LARGE LOW PRESSURE SYSTEM THAT WILL MOVE OVER MN MONDAY.
PREV DISCUSSION... /ISSUED 341 AM CDT SUN MAR 17 2013/
SHORT TERM...
TODAY THROUGH MONDAY AFTERNOON...
POTENT WINTER SYSTEM EXPECTED TO IMPACT THE NORTHLAND BEGINNING
TONIGHT AND LASTING THROUGH THE DAY MONDAY.
MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND ACCUMULATING
SNOW...LOCALLY HEAVY AMOUNTS POSSIBLE...BLOWING SNOW AND GUSTY
WINDS.
A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE ENTIRE NORTHLAND
FROM LATE THIS EVENING THROUGH MONDAY NIGHT.
HIGH PRESSURE CURRENTLY SITUATED OVER FAR NE MN/WRN ONTARIO IS
ALLOWING FOR MOSTLY CLEAR SKIES AND VERY COLD TEMPERATURES ACROSS
THE REGION THIS MORNING. A FEW LOCATIONS IN NE MN HAVE DROPPED
BELOW -20 F...WITH MOST AREAS SEEING WIDESPREAD 0 TO -10 DEG
READINGS. TEMPS SHOULD REBOUND RATHER QUICKLY WITH A HIGH SUN
ANGLE AND A RETURN SOUTHERLY FLOW ON THE WEST SIDE OF THE HIGH AS
IT MOVES EWD THROUGH THE GREAT LAKES REGION. HIGHS TODAY WILL TOP
OUT IN THE 20S.
THIS AFTERNOON...A ROBUST SFC LOW WILL DEVELOP IN THE FRONT RANGE
OF THE NRN ROCKIES AND MOVE EWD INTO THE WRN DAKOTAS. AHEAD OF
THIS SYSTEM...STRONG WAA AND MOISTURE TRANSPORT WILL OCCUR WITH
THE HELP OF A ROBUST LLJ...APPROX 40-50 KT AT 2-3K FT. MOST OF THE
FORCING FOR THIS SYSTEM WILL COME FROM MESOSCALE PROCESSES...AS
THE SYNOPTIC DYNAMICS WILL BE LIMITED. THE COMBINATION OF STRONG
ISENTROPIC LIFT...WAA...AND MODEST MID LEVEL F-GEN WILL ALLOW A
WELL-DEFINED AREA OF ENHANCED SNOW TO DEVELOP ON THE LEADING EDGE
OF THE LOW PRESSURE SYSTEM. THE TRACK OF THE LOW WILL BE CRITICAL
IN DETERMINING WHERE THE HIGHEST SNOW AMTS SET UP. IN THE PAST FEW
DAYS...MODELS HAVE BEEN TRENDING THE TRACK FURTHER NWD ACROSS FAR
NERN MN. HOWEVER...THE PAST COUPLE RUNS OF THE GEM AND ECMWF HAVE
TRENDED BACK TO THE SOUTH. THIS WOULD PLACE A GOOD PORTION OF NERN
MN IN THE FAVORABLE AREA OF THE DEFORMATION ZONE AS THE LOW MOVES
E/NEWD. THE HEAVIEST SNOW RATES WILL LIKELY BE SEEN WITH THE
INITIAL BAND/AREA OF SNOW SUNDAY NIGHT/MONDAY MORNING. THERE IS
SOME INDICATION OF A DRY SLOT WRAPPING AROUND AND PUSHING IN FROM
THE SW MON AFTERNOON...WHICH COULD LIMIT THE AMT OF SNOW SOUTH OF
HIGHWAY 2 IN MN AND AREAS TO THE EAST. THE MOST FAVORABLE AREA OF
HEAVY SNOW WILL BE FROM THE IRON RANGE NWD...DUE TO A PROLONGED
PERIOD IN THE DEFORMATION ZONE...AND ALONG THE ELEVATED TERRAIN OF
THE ARROWHEAD FROM TWO HARBORS NWD...DUE TO LAKE/TERRAIN
ENHANCEMENT. MOST AREAS TO THE SOUTH WILL LIKELY SEE 3-5
INCHES...WITH CLOSER TO 4-7 INCHES ACROSS THE NORTH AND ALONG THE
NORTH SHORE. THIS IS AN INITIAL ASSESSMENT...AND
MORNING/AFTERNOON MODEL GUIDANCE WILL SHED MORE LIGHT ON POTENTIAL
SNOW AMOUNTS. HIGHER AMTS NOT OF THE QUESTION...AND UPGRADES TO
WINTER STORM WARNINGS ARE POSSIBLE.
THE OTHER CONCERN WITH THIS SYSTEM WILL BE THE GUSTY W/NW WINDS
AND AREAS OF BLOWING SNOW...CAUSING REDUCED VSBYS AND DANGEROUS
TRAVEL CONDITIONS. A TIGHT PRESSURE GRADIENT ON THE WRN SIDE OF
THE DEPARTING LOW MON AFTERNOON WILL PRODUCE GUSTS UP TO 30 MPH AT
TIMES. LOCALLY HIGHER GUSTS WILL BE POSSIBLE...AND POTENTIALLY
PRODUCE NEAR WHITE-OUT CONDITIONS...ESPECIALLY FROM LEECH LAKE TO
LAKE MILLE LACS AND AROUND THE TWIN PORTS AREA WHERE HIGHER GUSTS
ARE LIKELY.
LONG TERM...
MONDAY NIGHT THROUGH SATURDAY...
THE VERTICALLY STACKED SYSTEM MOVES OVER NORTHERN LAKE SUPERIOR
BY 12Z TUESDAY. WILL CONTINUE TO SEE LIGHT SNOW IN THE CAA PATTERN
AND EMBEDDED SHORT WAVE ENERGY ROTATING AROUND THE LOW MONDAY
NIGHT. AS THIS SYSTEM SLOWLY LIFTS TO THE ENE INTO ONTARIO...COLD
AIR WILL CONTINUE TO SURGE INTO THE FA WITH MORE SHORT WAVE
ENERGY. HOWEVER...DRY HIGH PRESSURE IS WORKING INTO THE FA FROM
THE NORTHERN PLAINS. EXPECT THE LIGHT SNOW TO BE LIMITED TO THE
ARROWHEAD AND SOME FLURRIES IN NW WI. DIALED BACK ON THE LES
MENTION AS MODEL DIFFERENCES MAKE IT DIFFICULT TO GO WITH HIGHER
POPS/QPF/SNOW AMOUNTS. LITTLE CHANGE TO THE UPPER LEVEL PATTERN
WITH A WNW FLOW AND HIGH PRESSURE AT THE SFC. ONLY MENTION OF
LIGHT SNOW WILL BE ALONG THE SOUTH SHORE OF LS OVER ASHLAND AND
IRON COUNTIES THROUGH THURSDAY. QUIET WEATHER THURSDAY NIGHT
THROUGH SATURDAY.
&&
.POINT TEMPS/POPS...
DLH 21 19 27 5 / 0 90 90 20
INL 21 15 24 -1 / 10 100 90 20
BRD 23 21 24 2 / 10 90 70 10
HYR 25 17 29 4 / 0 80 90 20
ASX 25 18 32 10 / 0 80 90 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO 5 AM CDT TUESDAY FOR
MNZ012-020-021.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT CDT
MONDAY NIGHT FOR MNZ010-018-025-026-033>036.
WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR MNZ011-019-037-038.
WI...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ001-006-007.
WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ002>004-008-009.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....DAP
AVIATION...DAP
AREA FORECAST DISCUSSION
NWS DULUTH MN
1006 AM CDT SUN MAR 17 2013
.UPDATE...
THE FORECAST WAS UPDATED THROUGH TONIGHT. THE MAIN CHANGES
WERE TO SKY COVER. IT APPEARS THE COMBINATION OF BKN/OVC MID/LOW
LEVEL CLOUDS IN WESTERN MINNESOTA MOVING TOWARDS THE
NORTHLAND AND INCREASING LOW LEVEL CLOUDS ACROSS THE EASTERN
FORECAST AREA THIS AFTERNOON WILL RESULT IN A GENERALLY INCREASING
CLOUD COVER TREND THROUGH THE AFTERNOON. THE 12Z NAM12 SOUNDINGS
ARE SHOWING THAT CONVECTIVE TEMPERATURES WILL BE REACHED EARLY
THIS AFTERNOON AND LIKELY RESULT IN AT LEAST SOME SCATTERED LOW
LEVEL CLOUDS ACROSS THE EASTERN FORECAST. THIS SHOWS UP TOO IN
RECENT HRRR MODEL RUNS. ALSO...THERE IS PLENTY OF BKN/OVC MID/LOW
LEVEL CLOUDS MOVING THROUGH WESTERN MINNESOTA AND THE EASTERN
DAKOTAS ON PATH TOWARDS THE NORTHLAND...AND THERE DOES NOT APPEAR
TO BE MUCH TO STOP IT AS THE HIGH PRESSURE OVER THE GREAT LAKES
CONTINUES TO MOVE EAST. RECENT MODEL GUIDANCE WAS ALSO SHOWING
LOWER HIGH TEMPERATURES TODAY...WHICH SHOULD MAKE SOME SENSE
CONSIDERING HOW COLD IT GOT THIS MORNING AND THE INCREASING CLOUD
COVER TODAY. THEREFORE...DECREASED THE HIGHS A BIT. UPDATED THE
PCPN TIMING LATE THIS AFTERNOON AND INTO TONIGHT A BIT...BUT DID
NOT YET CHANGE THE PCPN/SNOWFALL FORECAST. I WILL LOOK MORE INTO
THIS EARLY THIS AFTERNOON. THE NIGHT SHIFT BRIEFED ME ABOUT THE
DIFFERENCES THE MODELS HAVE IN THE TRACK OF THE SURFACE LOW WITH
THE APPROACHING WINTER STORM SYSTEM. THE 00Z/06Z NAM12 STILL HAD A
MUCH MORE NORTHERN TRACK THAN THE OTHER MODELS...BUT I AM HAPPY TO
SEE THAT THE RECENT 12Z NAM12 CAME IN WITH A TRACK MUCH MORE SOUTH
AND SIMILAR TO THE ECMWF AND GFS. HOPEFULLY THE OTHER 12Z MODEL
RUNS WILL FINALLY FIND SOME CONSENSUS...ESPECIALLY THE GEM...WHICH
IS THE OTHER OUTLIER DUE TO ITS MORE SOUTHERN TRACK.
&&
.PREV DISCUSSION... /ISSUED 640 AM CDT SUN MAR 17 2013/
AVIATION...12Z TAFS.
VFR UNTIL ABOUT 03Z WHEN MVFR CIGS/VSBYS IN LIGHT SNOW BEGIN TO
SPREAD ACROSS THE TERMINALS FROM W TO E. THIS IS IN RESPONSE TO
THE LARGE LOW PRESSURE SYSTEM THAT WILL MOVE OVER MN MONDAY.
PREV DISCUSSION... /ISSUED 341 AM CDT SUN MAR 17 2013/
SHORT TERM...
TODAY THROUGH MONDAY AFTERNOON...
POTENT WINTER SYSTEM EXPECTED TO IMPACT THE NORTHLAND BEGINNING
TONIGHT AND LASTING THROUGH THE DAY MONDAY.
MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND ACCUMULATING
SNOW...LOCALLY HEAVY AMOUNTS POSSIBLE...BLOWING SNOW AND GUSTY
WINDS.
A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE ENTIRE NORTHLAND
FROM LATE THIS EVENING THROUGH MONDAY NIGHT.
HIGH PRESSURE CURRENTLY SITUATED OVER FAR NE MN/WRN ONTARIO IS
ALLOWING FOR MOSTLY CLEAR SKIES AND VERY COLD TEMPERATURES ACROSS
THE REGION THIS MORNING. A FEW LOCATIONS IN NE MN HAVE DROPPED
BELOW -20 F...WITH MOST AREAS SEEING WIDESPREAD 0 TO -10 DEG
READINGS. TEMPS SHOULD REBOUND RATHER QUICKLY WITH A HIGH SUN
ANGLE AND A RETURN SOUTHERLY FLOW ON THE WEST SIDE OF THE HIGH AS
IT MOVES EWD THROUGH THE GREAT LAKES REGION. HIGHS TODAY WILL TOP
OUT IN THE 20S.
THIS AFTERNOON...A ROBUST SFC LOW WILL DEVELOP IN THE FRONT RANGE
OF THE NRN ROCKIES AND MOVE EWD INTO THE WRN DAKOTAS. AHEAD OF
THIS SYSTEM...STRONG WAA AND MOISTURE TRANSPORT WILL OCCUR WITH
THE HELP OF A ROBUST LLJ...APPROX 40-50 KT AT 2-3K FT. MOST OF THE
FORCING FOR THIS SYSTEM WILL COME FROM MESOSCALE PROCESSES...AS
THE SYNOPTIC DYNAMICS WILL BE LIMITED. THE COMBINATION OF STRONG
ISENTROPIC LIFT...WAA...AND MODEST MID LEVEL F-GEN WILL ALLOW A
WELL-DEFINED AREA OF ENHANCED SNOW TO DEVELOP ON THE LEADING EDGE
OF THE LOW PRESSURE SYSTEM. THE TRACK OF THE LOW WILL BE CRITICAL
IN DETERMINING WHERE THE HIGHEST SNOW AMTS SET UP. IN THE PAST FEW
DAYS...MODELS HAVE BEEN TRENDING THE TRACK FURTHER NWD ACROSS FAR
NERN MN. HOWEVER...THE PAST COUPLE RUNS OF THE GEM AND ECMWF HAVE
TRENDED BACK TO THE SOUTH. THIS WOULD PLACE A GOOD PORTION OF NERN
MN IN THE FAVORABLE AREA OF THE DEFORMATION ZONE AS THE LOW MOVES
E/NEWD. THE HEAVIEST SNOW RATES WILL LIKELY BE SEEN WITH THE
INITIAL BAND/AREA OF SNOW SUNDAY NIGHT/MONDAY MORNING. THERE IS
SOME INDICATION OF A DRY SLOT WRAPPING AROUND AND PUSHING IN FROM
THE SW MON AFTERNOON...WHICH COULD LIMIT THE AMT OF SNOW SOUTH OF
HIGHWAY 2 IN MN AND AREAS TO THE EAST. THE MOST FAVORABLE AREA OF
HEAVY SNOW WILL BE FROM THE IRON RANGE NWD...DUE TO A PROLONGED
PERIOD IN THE DEFORMATION ZONE...AND ALONG THE ELEVATED TERRAIN OF
THE ARROWHEAD FROM TWO HARBORS NWD...DUE TO LAKE/TERRAIN
ENHANCEMENT. MOST AREAS TO THE SOUTH WILL LIKELY SEE 3-5
INCHES...WITH CLOSER TO 4-7 INCHES ACROSS THE NORTH AND ALONG THE
NORTH SHORE. THIS IS AN INITIAL ASSESSMENT...AND
MORNING/AFTERNOON MODEL GUIDANCE WILL SHED MORE LIGHT ON POTENTIAL
SNOW AMOUNTS. HIGHER AMTS NOT OF THE QUESTION...AND UPGRADES TO
WINTER STORM WARNINGS ARE POSSIBLE.
THE OTHER CONCERN WITH THIS SYSTEM WILL BE THE GUSTY W/NW WINDS
AND AREAS OF BLOWING SNOW...CAUSING REDUCED VSBYS AND DANGEROUS
TRAVEL CONDITIONS. A TIGHT PRESSURE GRADIENT ON THE WRN SIDE OF
THE DEPARTING LOW MON AFTERNOON WILL PRODUCE GUSTS UP TO 30 MPH AT
TIMES. LOCALLY HIGHER GUSTS WILL BE POSSIBLE...AND POTENTIALLY
PRODUCE NEAR WHITE-OUT CONDITIONS...ESPECIALLY FROM LEECH LAKE TO
LAKE MILLE LACS AND AROUND THE TWIN PORTS AREA WHERE HIGHER GUSTS
ARE LIKELY.
LONG TERM...
MONDAY NIGHT THROUGH SATURDAY...
THE VERTICALLY STACKED SYSTEM MOVES OVER NORTHERN LAKE SUPERIOR
BY 12Z TUESDAY. WILL CONTINUE TO SEE LIGHT SNOW IN THE CAA PATTERN
AND EMBEDDED SHORT WAVE ENERGY ROTATING AROUND THE LOW MONDAY
NIGHT. AS THIS SYSTEM SLOWLY LIFTS TO THE ENE INTO ONTARIO...COLD
AIR WILL CONTINUE TO SURGE INTO THE FA WITH MORE SHORT WAVE
ENERGY. HOWEVER...DRY HIGH PRESSURE IS WORKING INTO THE FA FROM
THE NORTHERN PLAINS. EXPECT THE LIGHT SNOW TO BE LIMITED TO THE
ARROWHEAD AND SOME FLURRIES IN NW WI. DIALED BACK ON THE LES
MENTION AS MODEL DIFFERENCES MAKE IT DIFFICULT TO GO WITH HIGHER
POPS/QPF/SNOW AMOUNTS. LITTLE CHANGE TO THE UPPER LEVEL PATTERN
WITH A WNW FLOW AND HIGH PRESSURE AT THE SFC. ONLY MENTION OF
LIGHT SNOW WILL BE ALONG THE SOUTH SHORE OF LS OVER ASHLAND AND
IRON COUNTIES THROUGH THURSDAY. QUIET WEATHER THURSDAY NIGHT
THROUGH SATURDAY.
&&
.POINT TEMPS/POPS...
DLH 21 19 27 5 / 0 90 90 20
INL 21 15 24 -1 / 10 100 90 20
BRD 23 21 24 2 / 10 90 70 10
HYR 26 17 29 4 / 0 80 90 20
ASX 25 18 32 10 / 0 80 90 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO 5 AM CDT TUESDAY FOR
MNZ012-020-021.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT CDT
MONDAY NIGHT FOR MNZ010-018-025-026-033>036.
WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR MNZ011-019-037-038.
WI...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ001-006-007.
WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ002>004-008-009.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....DAP
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
121 PM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 247 AM CDT SUN MAR 17 2013
IN THE ANALYSIS OF THE 06Z MSL PLOT...LOW PRESSURE WAS CENTERED OVER
SOUTHWEST MONTANA WITH A WARM FRONT DRAPED THROUGH CENTRAL WYOMING
TO EASTERN COLORADO. ALSO...A COLD FRONT STRETCHED FROM THE LOW
THROUGH EASTERN BRITISH COLUMBIA TO THE GULF OF ALASKA.
OTHERWISE...HIGH PRESSURE DOMINATED THE SCENE IN THE WESTERN GREAT
LAKES AND THE NORTHERN PLAINS NEAR THE CANADIAN BORDER.
&&
.UPDATE...
ISSUED AT 1017 AM CDT SUN MAR 17 2013
FORECAST HAS BEEN UPDATED TO SLOW THE TIMING OF RAIN SHOWERS INTO
THE PANHANDLE UNTIL EARLY AFTERNOON AND TO EXTEND THE COVERAGE OF
FREEZING DRIZZLE FOR ANOTHER SEVERAL HOURS IN THE COUNTIES
SURROUNDING THE HIGHWAY 83 CORRIDOR.
AT 15Z...THE WARM FRONT REMAINS OUT ALONG THE FRONT RANGE OF THE
ROCKIES...WITH THE COLD FRONT OUT OVER NORTHWEST WYOMING AND
IDAHO. AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE
SYSTEM...WINDS HAVE BEEN INCREASING ACROSS THE LOCAL AREA. THERE
ARE SOME WEAK AND VERY SCATTERED RADAR ECHOES BEING PICKED UP
OVER THE PANHANDLE AHEAD OF THE WARM FRONT...BUT DON/T EXPECT ANY
MEASURABLE RAINFALL UNTIL THE FRONT GETS CLOSER AFTER 18Z.
ALSO...WITH THE STRATUS HANGING IN...TEMPERATURES HAVE BEEN SLOW
TO WARM OVER THE EASTERN 2/3RDS OF THE FORECAST AREA...WITH MOST
OF THESE AREAS REMAINING BELOW FREEZING. ALTHOUGH RADAR IS NOT
SHOWING MUCH...AND ASOS/AWOS OBSERVATIONS ARE NOT PICKING UP ON
THE DRIZZLE...BELIEVE THE LOWERED VISIBILITIES IS WHERE THE
FREEZING DRIZZLE IS OCCURRING...ALTHOUGH IT IS VERY LIGHT. IR
SATELLITE ALSO SHOWS CLOUD TOPS WARMER THAN -10C SO ANYTHING
OCCURRING WOULD BE DRIZZLE. AS WINDS CONTINUE TO PICK UP...WOULD
EXPECT THE STRATUS TO BEGIN BREAKING UP YET THIS MORNING AND THE
DRIZZLE COME TO AN END.
WIND ADVISORY LOOKING ON TRACK...AS WINDS SHOULD CONTINUE TO PICK
UP INTO THE AFTERNOON.WITH THE RAP INDICATING 850MB WINDS AT 55KTS
THIS AFTERNOON OVER NORTH CENTRAL NEBRASKA...CONTINUE TO THINK
GUSTS TO 45 MPH ARE LIKELY.
UPDATE ISSUED AT 640 AM CDT SUN MAR 17 2013
NORTH PLATTE AND PROBABLY OGALLALA AND IMPERIAL HAVE BEEN PICKING
UP SOME DRIZZLE. WITH TEMPERATURES BELOW FREEZING THROUGH THE
SOUTHWEST...FREEZING DRIZZLE IS NOT OUT OF THE QUESTION THROUGH
ABOUT MID-MORNING.
&&
.SHORT TERM...(TODAY AND MONDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
AS THE WARM FRONT MAKES ITS WAY EASTWARD INTO WESTERN NEBRASKA...
AIR IS LIFTED INTO A HYDRO-STATICALLY UNSTABLE ENVIRONMENT AS
INDICATED BY FOLDING IN A CROSS-SECTION OF THETA-E. A LOOK AT
CONVECTIVE PARAMETERS INDICATES SOME INSTABILITY WITH PRECIPITABLE
WATER VALUES APPROACHING 0.5 INCH. FROM THAT...IT APPEARS THAT THERE
WILL BE AT LEAST ISOLATED THUNDERSTORMS EMBEDDED IN THE BROADER AREA
OF SHOWERS. THIS IS REFLECTED FAIRLY WELL IN THE HOURLY
PRECIPITATION SHOWN BY THE RAP13 SHORT RANGE MODEL AND IN THE GFS
OUTPUT AND EVEN IN THE GEM REGIONAL AND EVEN THE NORTHERN HEMISPHERE
GEM. THE RESULT IS THAT WE HAVE FAIRLY HIGH CONFIDENCE THAT MUCH OF
CENTRAL AND WESTERN NEBRASKA WILL HAVE AT LEAST SCATTERED SHOWERS
THROUGHOUT THE AREA WITH ISOLATED THUNDERSTORMS THIS AFTERNOON
THROUGH LATE THIS EVENING IN SOUTHWEST NEBRASKA. THE COLD FRONT
COMING ACROSS LATE THIS EVENING WILL BRING A QUICK END TO ANY
PRECIPITATION SHORTLY AFTER 06Z.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
MAINLY DRY CONDITIONS WITH NORTHWEST FLOW ALOFT TO START THE WEEK
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. GUSTY NORTHWEST WINDS
ARE EXPECTED IN THE WAKE OF THE SUNDAY NIGHT SYSTEM ON MONDAY.
GOOD MIXING COULD YIELD WIND SPEEDS NEAR WIND ADVISORY. OTHERWISE AN
ARCTIC FRONTAL BOUNDARY WILL OSCILLATE BACK AND FORTH FROM
NORTHEAST TO SOUTHWEST ACROSS THE AREA THROUGH MIDWEEK. THIS FRONT
WILL KEEP THE NORTHEAST SECTIONS OF THE AREA AROUND ONEILL QUITE
CHILLY...WITH TEMPERATURES MOSTLY BELOW NORMAL FOR THIS TIME OF
YEAR. FARTHER SOUTHWEST ACROSS WESTERN AND SOUTHWEST
NEBRASKA...SOMEWHAT WARMER CONDITIONS ARE EXPECTED...WITH
TEMPERATURES RIGHT AROUND NORMAL. ALL AREAS WILL BE BELOW AVERAGE
TEMPERATURE WISE BY THE END OF THE WEEK...AS THE ARCTIC FRONT
MOVES SOUTH IN RESPONSE TO STRONG SFC HIGH PRESSURE NOSING SOUTH
INTO THE NORTHERN PLAINS.
FOLLOWED THE GFS ENSEMBLE MEAN IN REGARDS TO PRECIP CHANCES...AND 30
TO 40 PERCENT SEEMS REASONABLE WEDNESDAY NIGHT THROUGH FRIDAY AS A
SIGNIFICANT DISTURBANCE DROPS SOUTHEAST INTO THE AREA. OPERATIONAL
MODELS HAVE BEEN STRUGGLING ON HOW TO HANDLE THIS ENERGY DROPPING
SOUTHEAST INTO THE AREA. THIS IS LIKELY DUE TO A BLOCKY TYPE UPPER
PATTERN. FELT THE GFS ENSEMBLE MEAN WAS THE WAY TO LEAN AT THIS
POINT...AND FOR WHAT IT/S WORTH...THE MEAN REPRESENTS THE
OPERATIONAL GFS OUTPUT BETTER THAN THE ECMWF. THIS WOULD BE A
WETTER SOLUTION FOR US...AND THE PRECIPITATION WOULD BE MOSTLY IN
THE FORM OF SNOW DUE TO COLD AIR IN PLACE. STAY TUNED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 120 PM CDT SUN MAR 17 2013
FORECAST CONCERNS OVER THE NEXT 24 HOURS DEAL WITH
CEILINGS...SHOWER CHANCES...AND WINDS AS PASSAGES OF BOTH WARM AND
COLD FRONTS WILL OCCUR. MVFR CEILINGS WILL IMPROVE THIS AFTERNOON
AS THE STRATUS BREAKS UP. BREEZY TO STRONG SOUTHERLY WINDS ARE
ONGOING ACROSS WESTERN AND NORTH CENTRAL NEBRASKA EARLY SUNDAY
AFTERNOON. WINDS ARE EXPECTED TO INCREASE FURTHER YET THIS
AFTERNOON...THEN SWITCH TO THW SOUTHWEST AS THE WARM FRONT MOVES
THROUGH THIS EVENING. AHEAD OF THE FRONT...SCATTERED RAIN SHOWERS
AND A FEW EMBEDDED THUNDERSTORMS WILL OCCUR ACROSS THE AREA. WITH
THE NATURE OF JUST ISOLATED THUNDER...DON/T HAVE THE CONFIDENCE IN
THUNDER OCCURING AT EITHER KVTN OR KLBF SO HAVE NOT INCLUDED THE
TS MENTION IN THE FORECAST AND WILL MONITOR AND UPDATE THE
FORECAST IF NEEDED. THE COLD FRONT WILL MOVE THROUGH LATE THIS
EVENING AND OVERNIGHT TO SWITCH WINDS TO THE NORTHWEST. DO EXPECT
STRONG WINDS AGAIN ON MONDAY BEHIND THE FRONT WITH GUSTS BETWEEN
25 AND 35 KTS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ005-
006-008-009-023>025-094.
WIND ADVISORY UNTIL 10 PM MDT THIS EVENING FOR NEZ004-022-056.
&&
$$
SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...TAYLOR
AVIATION...BROOKS
AREA FORECAST DISCUSSION...UPDATED
NWS OMAHA/VALLEY NE
1246 PM CDT SUN MAR 17 2013
.UPDATE...
&&
.AVIATION...18Z TAFS FOR KOMA...KLNK...KOFK.
MAIN CONCERN IS TIMING PCPN/LOW CIGS LATER TONIGHT. AN UPPER
DISTURBANCE IS EXPECTED TO MOVE ACROSS THE DAKOTAS TONIGHT WITH
ATTENDANT COLD FRONT SWEEPING INTO THE CNTRL PLAINS. AT THIS POINT
ANTICIPATE MVFR CONDITIONS WILL GRADUALLY EXPAND SWD OVER ERN NEB
EARLY THIS EVENING. AS OF NOW BELIEVE BEST CHANCE FOR -RA/SN MIX
OCCURRING GENERALLY BTWN 18 /05Z-11Z...THUS HAVE INCLUDED PROB30
GROUPS AT ALL TERMINALS. CROSS WIND THREAT AT THIS TIME APPEARS
MINIMAL DURING FRONTAL PASSAGE.
DEE
PREV DISCUSSION... /ISSUED 328 AM CDT SUN MAR 17 2013/
DISCUSSION...
THE CHANCE FOR RAIN AND SNOW TONIGHT THEN WINDS BEHIND COLD FRONT
MONDAY ARE THE PRIMARY FORECAST CONCERNS.
A COUPLE OF AREAS OF PRECIPITATION WERE IN OR NEAR OUR CWA THIS
MORNING. LIGHT SNOW MOVED FROM NORTH CENTRAL INTO NORTHEAST NEBRASKA
DURING THE LATE EVENING...DROPPING A DUSTING TO A HALF INCH OF SNOW
FOR SOME OF OUR NORTHERN AREAS. THIS SEEMED TO BE TIED TO 90-120KT
300MB JET STRETCHING FROM NORTHERN NEBRASKA INTO THE GREAT LAKES.
WITH THAT JET SHIFTING EAST THIS MORNING...THINK ANY LINGERING SNOW
SHOWERS WILL BE SHORT-LIVED AFTER SUNRISE. SHORT RANGE MODELS RAP
AND HRRR CONCUR. THE SECOND AREA OF PRECIPITATION WAS STAYING MOSTLY
SOUTH OF THE CWA ACROSS NORTHERN KANSAS...AND LOOKED TO BE CAUSED BY
MID LEVEL WARM ADVECTION AHEAD OF 700MB SHORTWAVE MIGRATING EAST
THROUGH KANSAS. A FEW RADAR RETURNS MOVED ACROSS THE SOUTHEAST
NEBRASKA BORDER...BUT TRENDS HAVE BEEN TO CONCENTRATE PRECIP JUST
SOUTH OF OUR AREA. SO ONLY SMALL CHANCES EARLY TODAY THERE...WITH
LIGHT SNOW THE MAIN PRECIP TYPE.
ATTENTION THEN TURNS TO STRONG MID LEVEL SHORTWAVE NOW DIVING
THROUGH WASHINGTON AND OREGON INTO IDAHO. THIS FEATURE WILL RACE
EAST AND STRENGTHEN TODAY...REACHING THE WESTERN DAKOTAS BY
00Z...WITH AXIS OF MID LEVEL TROUGH SWINGING THROUGH OUR AREA MONDAY
MORNING. STRONG SURFACE LOW WILL DEVELOP IN THE NORTHERN HIGH PLAINS
THROUGH THE DAY...THEN ROTATE THROUGH THE DAKOTAS OVERNIGHT WHILE
DRIVING A COLD FRONT THROUGH NEBRASKA AND WESTERN IOWA BY SUNRISE
MONDAY. SOUTHEAST TO SOUTH LOW LEVEL FLOW WILL DEVELOP IN OUR AREA
TODAY IN RESPONSE TO LOWERING PRESSURES TO OUR NORTHWEST...AND WILL
PUSH TEMPERATURES TOWARD 40 THIS AFTERNOON. MID LEVEL THETA-E
INCREASE IN DIFFLUENT FLOW REGIME AHEAD OF TROUGH WILL PROVIDE
SUFFICIENT MOISTURE/LIFT FOR PRECIPITATION AS EARLY AS THIS
AFTERNOON IN CENTRAL AND PERHAPS NORTHEAST NEBRASKA. BUT BETTER
CHANCES COME OVERNIGHT AHEAD OF SURFACE COLD FRONT UNDER CORE OF MID
LEVEL JET SEGMENT. HAVE KEPT PRECIPITATION CHANCES RELATIVELY
HIGH...WITH BEST CHANCES ACROSS THE NORTH NEARER BETTER COMBINATION
OF LIFT/MOISTURE.
PRECIPITATION TYPE CONTINUES TO BE AN ISSUE AS SURFACE LAYER REMAINS
ABOVE FREEZING UNTIL COLD FRONT ARRIVES. MODEL DEPICTIONS OF LAYER
TEMPERATURE PROFILES ARE NOT CONSISTENT WITH EACH OTHER...AND
TEMPERATURE TRENDS WITHIN THE SAME MODEL SPORADICALLY MOVE THERMAL
PROFILE FROM JUST ABOVE TO JUST BELOW FREEZING AND BACK AGAIN WITH
TIME. THIS IS LIKELY DUE TO DYNAMIC COOLING EFFECTS GIVEN VIGOROUS
BUT SMALL AREAS OF LIFT UNDER FAST FLOW. SO A VARIETY OF WEATHER
TYPES ARE POSSIBLE FROM TIME TO TIME OVERNIGHT...BUT WILL FOCUS THIS
FORECAST ON TIMING OF PREDOMINANT WEATHER TYPE CHANGING FROM MAINLY
RAIN TO MAINLY SNOW...AND LET POTENTIAL SNOW AMOUNTS FALL OUT OF
THAT THINKING.
THERMAL PROFILES WILL SUPPORT RAIN FROM LATE THIS AFTERNOON THROUGH
MID EVENING...WITH THICKNESS PROGS SUGGESTING A TRANSITION TOWARD
SNOW IN OUR NORTHWEST BY 03Z. THAT TREND WILL QUICKLY SWING EAST AND
SOUTHEAST THROUGH 06Z...WITH MAINLY SNOW EXPECTED IN OUR SOUTH AFTER
09Z. BETTER COOLING REGIME IS EXPECTED ACROSS OUR NORTH...SO HIGHER
POTENTIAL SNOW TOTALS THERE. HOWEVER...STRONG LIFT NEAR AND
NORTH/NORTHEAST OF THE OMAHA METRO AREA AROUND 06Z MAY END UP BEING
THE MAIN SNOW ZONE WITH THIS SYSTEM. AN ENSEMBLE APPROACH TO SNOW
AMOUNT FORECAST SUGGESTS 1 TO 2 INCHES WILL BE COMMON FROM NORTHEAST
NEBRASKA INTO WEST CENTRAL IOWA. THIS COMBINES STRAIGHT MODEL
OUTPUT...COBB CALCULATIONS OF SEVERAL MODELS...AND A GARCIA
MANIPULATION OF MIXING RATIOS TAKING INTO ACCOUNT 6 HOUR PERIOD OF
PRECIPITATION AND A TRANSITION FROM RAIN TO SNOW OCCURRING NEAR THE
MIDWAY POINT OF THE PRECIP.
FAST-MOVING SYSTEM SHOULD TAKE MOST PRECIPITATION EAST OF OUR WESTERN
IOWA COUNTIES BY 12Z MONDAY. STRONG WINDS WILL FOLLOW DURING THE DAY
AS UNIDIRECTIONAL NORTHWEST FLOW AND STRONG COLD ADVECTION POINT TO
EFFECTIVE TRANSFER OF MOMENTUM IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS STILL SHOW THE POTENTIAL FOR 40MPH WIND GUSTS ON MONDAY.
AND AM NOT EXPECTING A LOT OF WARMING MONDAY GIVEN COLD ADVECTION
DESPITE CLEARING SKIES. HAVE HIGHS GENERALLY IN THE 30S NORTH TO
LOWER 40S SOUTH.
THE REST OF THE WEEK STILL LOOKS TO BE COOL. TUESDAY MAY BE THE
WARMEST...OR LEAST COOL...DAY OF THE WEEK WHERE A RELATIVELY MILD
START AND SUNSHINE ALLOW TEMPS TO REBOUND INTO 40S. OTHERWISE
NORTHWEST MID LEVEL FLOW AT MID WEEK WILL BE REPLACED BY WAVE/LOW
APPROACHING FOR THE END OF THE WEEK INTO THE WEEKEND. OFF-AND-ON
PRECIPITATION CHANCES WILL RESULT BEGINNING WEDNESDAY NIGHT...WITH
CLOUDS AND LITTLE IN THE WAY OF WARM/COLD ADVECTION SUGGESTING
TEMPERATURES WILL BE RANGE-BOUND IN THE 20S FOR LOWS AND 30S OR
LOWER 40S FOR HIGHS.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1017 AM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 247 AM CDT SUN MAR 17 2013
IN THE ANALYSIS OF THE 06Z MSL PLOT...LOW PRESSURE WAS CENTERED OVER
SOUTHWEST MONTANA WITH A WARM FRONT DRAPED THROUGH CENTRAL WYOMING
TO EASTERN COLORADO. ALSO...A COLD FRONT STRETCHED FROM THE LOW
THROUGH EASTERN BRITISH COLUMBIA TO THE GULF OF ALASKA.
OTHERWISE...HIGH PRESSURE DOMINATED THE SCENE IN THE WESTERN GREAT
LAKES AND THE NORTHERN PLAINS NEAR THE CANADIAN BORDER.
&&
.UPDATE...
ISSUED AT 1017 AM CDT SUN MAR 17 2013
FORECAST HAS BEEN UPDATED TO SLOW THE TIMING OF RAIN SHOWERS INTO
THE PANHANDLE UNTIL EARLY AFTERNOON AND TO EXTEND THE COVERAGE OF
FREEZING DRIZZLE FOR ANOTHER SEVERAL HOURS IN THE COUNTIES
SURROUNDING THE HIGHWAY 83 CORRIDOR.
AT 15Z...THE WARM FRONT REMAINS OUT ALONG THE FRONT RANGE OF THE
ROCKIES...WITH THE COLD FRONT OUT OVER NORTHWEST WYOMING AND
IDAHO. AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE
SYSTEM...WINDS HAVE BEEN INCREASING ACROSS THE LOCAL AREA. THERE
ARE SOME WEAK AND VERY SCATTERED RADAR ECHOES BEING PICKED UP
OVER THE PANHANDLE AHEAD OF THE WARM FRONT...BUT DON/T EXPECT ANY
MEASURABLE RAINFALL UNTIL THE FRONT GETS CLOSER AFTER 18Z.
ALSO...WITH THE STRATUS HANGING IN...TEMPERATURES HAVE BEEN SLOW
TO WARM OVER THE EASTERN 2/3RDS OF THE FORECAST AREA...WITH MOST
OF THESE AREAS REMAINING BELOW FREEZING. ALTHOUGH RADAR IS NOT
SHOWING MUCH...AND ASOS/AWOS OBSERVATIONS ARE NOT PICKING UP ON
THE DRIZZLE...BELIEVE THE LOWERED VISIBILITIES IS WHERE THE
FREEZING DRIZZLE IS OCCURRING...ALTHOUGH IT IS VERY LIGHT. IR
SATELLITE ALSO SHOWS CLOUD TOPS WARMER THAN -10C SO ANYTHING
OCCURRING WOULD BE DRIZZLE. AS WINDS CONTINUE TO PICK UP...WOULD
EXPECT THE STRATUS TO BEGIN BREAKING UP YET THIS MORNING AND THE
DRIZZLE COME TO AN END.
WIND ADVISORY LOOKING ON TRACK...AS WINDS SHOULD CONTINUE TO PICK
UP INTO THE AFTERNOON.WITH THE RAP INDICATING 850MB WINDS AT 55KTS
THIS AFTERNOON OVER NORTH CENTRAL NEBRASKA...CONTINUE TO THINK
GUSTS TO 45 MPH ARE LIKELY.
UPDATE ISSUED AT 640 AM CDT SUN MAR 17 2013
NORTH PLATTE AND PROBABLY OGALLALA AND IMPERIAL HAVE BEEN PICKING
UP SOME DRIZZLE. WITH TEMPERATURES BELOW FREEZING THROUGH THE
SOUTHWEST...FREEZING DRIZZLE IS NOT OUT OF THE QUESTION THROUGH
ABOUT MID-MORNING.
&&
.SHORT TERM...(TODAY AND SUNDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
AS THE WARM FRONT MAKES ITS WAY EASTWARD INTO WESTERN NEBRASKA...
AIR IS LIFTED INTO A HYDRO-STATICALLY UNSTABLE ENVIRONMENT AS
INDICATED BY FOLDING IN A CROSS-SECTION OF THETA-E. A LOOK AT
CONVECTIVE PARAMETERS INDICATES SOME INSTABILITY WITH PRECIPITABLE
WATER VALUES APPROACHING 0.5 INCH. FROM THAT...IT APPEARS THAT THERE
WILL BE AT LEAST ISOLATED THUNDERSTORMS EMBEDDED IN THE BROADER AREA
OF SHOWERS. THIS IS REFLECTED FAIRLY WELL IN THE HOURLY
PRECIPITATION SHOWN BY THE RAP13 SHORT RANGE MODEL AND IN THE GFS
OUTPUT AND EVEN IN THE GEM REGIONAL AND EVEN THE NORTHERN HEMISPHERE
GEM. THE RESULT IS THAT WE HAVE FAIRLY HIGH CONFIDENCE THAT MUCH OF
CENTRAL AND WESTERN NEBRASKA WILL HAVE AT LEAST SCATTERED SHOWERS
THROUGHOUT THE AREA WITH ISOLATED THUNDERSTORMS THIS AFTERNOON
THROUGH LATE THIS EVENING IN SOUTHWEST NEBRASKA. THE COLD FRONT
COMING ACROSS LATE THIS EVENING WILL BRING A QUICK END TO ANY
PRECIPITATION SHORTLY AFTER 06Z.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
MAINLY DRY CONDITIONS WITH NORTHWEST FLOW ALOFT TO START THE WEEK
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. GUSTY NORTHWEST WINDS
ARE EXPECTED IN THE WAKE OF THE SUNDAY NIGHT SYSTEM ON MONDAY.
GOOD MIXING COULD YIELD WIND SPEEDS NEAR WIND ADVISORY. OTHERWISE AN
ARCTIC FRONTAL BOUNDARY WILL OSCILLATE BACK AND FORTH FROM
NORTHEAST TO SOUTHWEST ACROSS THE AREA THROUGH MIDWEEK. THIS FRONT
WILL KEEP THE NORTHEAST SECTIONS OF THE AREA AROUND ONEILL QUITE
CHILLY...WITH TEMPERATURES MOSTLY BELOW NORMAL FOR THIS TIME OF
YEAR. FARTHER SOUTHWEST ACROSS WESTERN AND SOUTHWEST
NEBRASKA...SOMEWHAT WARMER CONDITIONS ARE EXPECTED...WITH
TEMPERATURES RIGHT AROUND NORMAL. ALL AREAS WILL BE BELOW AVERAGE
TEMPERATURE WISE BY THE END OF THE WEEK...AS THE ARCTIC FRONT
MOVES SOUTH IN RESPONSE TO STRONG SFC HIGH PRESSURE NOSING SOUTH
INTO THE NORTHERN PLAINS.
FOLLOWED THE GFS ENSEMBLE MEAN IN REGARDS TO PRECIP CHANCES...AND 30
TO 40 PERCENT SEEMS REASONABLE WEDNESDAY NIGHT THROUGH FRIDAY AS A
SIGNIFICANT DISTURBANCE DROPS SOUTHEAST INTO THE AREA. OPERATIONAL
MODELS HAVE BEEN STRUGGLING ON HOW TO HANDLE THIS ENERGY DROPPING
SOUTHEAST INTO THE AREA. THIS IS LIKELY DUE TO A BLOCKY TYPE UPPER
PATTERN. FELT THE GFS ENSEMBLE MEAN WAS THE WAY TO LEAN AT THIS
POINT...AND FOR WHAT IT/S WORTH...THE MEAN REPRESENTS THE
OPERATIONAL GFS OUTPUT BETTER THAN THE ECMWF. THIS WOULD BE A
WETTER SOLUTION FOR US...AND THE PRECIPITATION WOULD BE MOSTLY IN
THE FORM OF SNOW DUE TO COLD AIR IN PLACE. STAY TUNED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 640 AM CDT SUN MAR 17 2013
LOW CLOUDS AND DRIZZLE HAVE DEVELOPED OVER PARTS OF SOUTHWEST
NEBRASKA...INCLUDING LBF AND POSSIBLY IML AND OGA. WITH TEMPERATURES
AT OR BELOW 32F...LIGHT FREEZING DRIZZLE IS A THREAT. CEILINGS ARE
ALSO BELOW 1000 FEET AGL IN THAT AREA WITH SOME AS LOW AS 200 FEET
AGL. THE FREEZING DRIZZLE SHOULD END BY 15Z AS TEMPERATURES
INCREASE. THERE IS MORE UNCERTAINTY WITH THE CEILING LIFTING TO
ABOVE 1000 FEET AGL. CONDITIONAL CLIMATOLOGY INDICATES THAT 18Z IS A
GOOD ESTIMATE AND THE SHORT RANGE FORECAST SIMULATIONS FAVOR THAT
TIME AS WELL.
ANOTHER ELEMENT WITH POTENTIAL IMPACT ON FLIGHT OPERATIONS IS WIND.
STRONG WIND AHEAD OF THE FRONT WILL BRING WINDY CONDITION BEGINNING
AS EARLY AS 16Z WITH WIND 190-210 INCREASING TO 26-28G34-38KT AT
ANW... VTN AND TIF. AT BBW...LBF...OGA AND IML THE SPEED WILL BE A
LITTLE LOWER AT 22-25G31-35KT.
ONE OTHER POTENTIAL PROBLEM COULD BE ISOLATED THUNDERSTORMS EMBEDDED
IN A BROADER AREA OF RAINSHOWERS THIS AFTERNOON AND EVENING. THE
COVERAGE OF THE THUNDERSTORMS WILL NOT BE HIGH...SO THE PROBABILITY
OF ANY ON SITE HAVING A THUNDERSTORM IS TOO LOW FOR INCLUSION IN THE
TERMINAL FORECASTS FOR LBF AND VTN.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ005-
006-008-009-023>025-094.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 10 PM MDT THIS EVENING
FOR NEZ004-022-056.
&&
$$
UPDATE1...SPRINGER
UPDATE2...BROOKS
SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...TAYLOR
AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
704 AM CDT SUN MAR 17 2013
.AVIATION...
12Z TAFS FOR KOMA...KLNK...KOFK.
VARIABLE MVFR/VFR CIGS THE PRIMARY CONCERN THIS MORNING THEN
DETERIORATING CONDITIONS LATER THIS AFTERNOON AND THIS EVENING.
A WEATHER SYSTEM IS MOVING ACROSS THE PLAINS THIS MORNING...WITH
THE PRIMARY FOCUS FOR PRECIPITATION ACROSS KANSAS AND MISSOURI.
PERIODS OF MVFR CIGS ARE POSSIBLE THROUGH THE MORNING WITH A
WEAKENING AREA OF LIGHT SNOW AND FLURRIES OVER NORTHEAST NEBRASKA.
LATER THIS AFTERNOON ANOTHER STRONGER WEATHER SYSTEM WILL MOVE
ACROSS THE NORTHERN AND CENTRAL PLAINS. THE RAIN COULD HOLD OFF TO
THE WEST BEFORE 00Z...HOWEVER OVERSPREAD THE TAF SITES TONIGHT
BETWEEN 00-06Z WITH RAIN CHANGING TO SNOW...MOVING OUT AFTER 06Z.
CIGS WILL MAINLY BE VFR...HOWEVER MVFR AND LOCAL IFR CONDITIONS
SHOULD EXPAND ACROSS THE TAF SITE THIS EVENING AS PRECIPITATION
DEVELOPS.
EAST WINDS WILL BECOME SOUTHEAST AND INCREASE TO 10 TO 16KTS WITH
SOME HIGHER GUSTS. THE COLD FRONT WILL BEGIN TO SWING THE WINDS
AROUND TO THE NORTHWEST AT KOFK AROUND 07-09Z. STRONG NORTHWEST
WINDS WILL DEVELOP AT ALL SITES LATER MONDAY.
ZAPOTOCNY
&&
.PREV DISCUSSION... /ISSUED 328 AM CDT SUN MAR 17 2013/
DISCUSSION...
THE CHANCE FOR RAIN AND SNOW TONIGHT THEN WINDS BEHIND COLD FRONT
MONDAY ARE THE PRIMARY FORECAST CONCERNS.
A COUPLE OF AREAS OF PRECIPITATION WERE IN OR NEAR OUR CWA THIS
MORNING. LIGHT SNOW MOVED FROM NORTH CENTRAL INTO NORTHEAST NEBRASKA
DURING THE LATE EVENING...DROPPING A DUSTING TO A HALF INCH OF SNOW
FOR SOME OF OUR NORTHERN AREAS. THIS SEEMED TO BE TIED TO 90-120KT
300MB JET STRETCHING FROM NORTHERN NEBRASKA INTO THE GREAT LAKES.
WITH THAT JET SHIFTING EAST THIS MORNING...THINK ANY LINGERING SNOW
SHOWERS WILL BE SHORT-LIVED AFTER SUNRISE. SHORT RANGE MODELS RAP
AND HRRR CONCUR. THE SECOND AREA OF PRECIPITATION WAS STAYING MOSTLY
SOUTH OF THE CWA ACROSS NORTHERN KANSAS...AND LOOKED TO BE CAUSED BY
MID LEVEL WARM ADVECTION AHEAD OF 700MB SHORTWAVE MIGRATING EAST
THROUGH KANSAS. A FEW RADAR RETURNS MOVED ACROSS THE SOUTHEAST
NEBRASKA BORDER...BUT TRENDS HAVE BEEN TO CONCENTRATE PRECIP JUST
SOUTH OF OUR AREA. SO ONLY SMALL CHANCES EARLY TODAY THERE...WITH
LIGHT SNOW THE MAIN PRECIP TYPE.
ATTENTION THEN TURNS TO STRONG MID LEVEL SHORTWAVE NOW DIVING
THROUGH WASHINGTON AND OREGON INTO IDAHO. THIS FEATURE WILL RACE
EAST AND STRENGTHEN TODAY...REACHING THE WESTERN DAKOTAS BY
00Z...WITH AXIS OF MID LEVEL TROUGH SWINGING THROUGH OUR AREA MONDAY
MORNING. STRONG SURFACE LOW WILL DEVELOP IN THE NORTHERN HIGH PLAINS
THROUGH THE DAY...THEN ROTATE THROUGH THE DAKOTAS OVERNIGHT WHILE
DRIVING A COLD FRONT THROUGH NEBRASKA AND WESTERN IOWA BY SUNRISE
MONDAY. SOUTHEAST TO SOUTH LOW LEVEL FLOW WILL DEVELOP IN OUR AREA
TODAY IN RESPONSE TO LOWERING PRESSURES TO OUR NORTHWEST...AND WILL
PUSH TEMPERATURES TOWARD 40 THIS AFTERNOON. MID LEVEL THETA-E
INCREASE IN DIFFLUENT FLOW REGIME AHEAD OF TROUGH WILL PROVIDE
SUFFICIENT MOISTURE/LIFT FOR PRECIPITATION AS EARLY AS THIS
AFTERNOON IN CENTRAL AND PERHAPS NORTHEAST NEBRASKA. BUT BETTER
CHANCES COME OVERNIGHT AHEAD OF SURFACE COLD FRONT UNDER CORE OF MID
LEVEL JET SEGMENT. HAVE KEPT PRECIPITATION CHANCES RELATIVELY
HIGH...WITH BEST CHANCES ACROSS THE NORTH NEARER BETTER COMBINATION
OF LIFT/MOISTURE.
PRECIPITATION TYPE CONTINUES TO BE AN ISSUE AS SURFACE LAYER REMAINS
ABOVE FREEZING UNTIL COLD FRONT ARRIVES. MODEL DEPICTIONS OF LAYER
TEMPERATURE PROFILES ARE NOT CONSISTENT WITH EACH OTHER...AND
TEMPERATURE TRENDS WITHIN THE SAME MODEL SPORADICALLY MOVE THERMAL
PROFILE FROM JUST ABOVE TO JUST BELOW FREEZING AND BACK AGAIN WITH
TIME. THIS IS LIKELY DUE TO DYNAMIC COOLING EFFECTS GIVEN VIGOROUS
BUT SMALL AREAS OF LIFT UNDER FAST FLOW. SO A VARIETY OF WEATHER
TYPES ARE POSSIBLE FROM TIME TO TIME OVERNIGHT...BUT WILL FOCUS THIS
FORECAST ON TIMING OF PREDOMINANT WEATHER TYPE CHANGING FROM MAINLY
RAIN TO MAINLY SNOW...AND LET POTENTIAL SNOW AMOUNTS FALL OUT OF
THAT THINKING.
THERMAL PROFILES WILL SUPPORT RAIN FROM LATE THIS AFTERNOON THROUGH
MID EVENING...WITH THICKNESS PROGS SUGGESTING A TRANSITION TOWARD
SNOW IN OUR NORTHWEST BY 03Z. THAT TREND WILL QUICKLY SWING EAST AND
SOUTHEAST THROUGH 06Z...WITH MAINLY SNOW EXPECTED IN OUR SOUTH AFTER
09Z. BETTER COOLING REGIME IS EXPECTED ACROSS OUR NORTH...SO HIGHER
POTENTIAL SNOW TOTALS THERE. HOWEVER...STRONG LIFT NEAR AND
NORTH/NORTHEAST OF THE OMAHA METRO AREA AROUND 06Z MAY END UP BEING
THE MAIN SNOW ZONE WITH THIS SYSTEM. AN ENSEMBLE APPROACH TO SNOW
AMOUNT FORECAST SUGGESTS 1 TO 2 INCHES WILL BE COMMON FROM NORTHEAST
NEBRASKA INTO WEST CENTRAL IOWA. THIS COMBINES STRAIGHT MODEL
OUTPUT...COBB CALCULATIONS OF SEVERAL MODELS...AND A GARCIA
MANIPULATION OF MIXING RATIOS TAKING INTO ACCOUNT 6 HOUR PERIOD OF
PRECIPITATION AND A TRANSITION FROM RAIN TO SNOW OCCURRING NEAR THE
MIDWAY POINT OF THE PRECIP.
FAST-MOVING SYSTEM SHOULD TAKE MOST PRECIPITATION EAST OF OUR WESTERN
IOWA COUNTIES BY 12Z MONDAY. STRONG WINDS WILL FOLLOW DURING THE DAY
AS UNIDIRECTIONAL NORTHWEST FLOW AND STRONG COLD ADVECTION POINT TO
EFFECTIVE TRANSFER OF MOMENTUM IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS STILL SHOW THE POTENTIAL FOR 40MPH WIND GUSTS ON MONDAY.
AND AM NOT EXPECTING A LOT OF WARMING MONDAY GIVEN COLD ADVECTION
DESPITE CLEARING SKIES. HAVE HIGHS GENERALLY IN THE 30S NORTH TO
LOWER 40S SOUTH.
THE REST OF THE WEEK STILL LOOKS TO BE COOL. TUESDAY MAY BE THE
WARMEST...OR LEAST COOL...DAY OF THE WEEK WHERE A RELATIVELY MILD
START AND SUNSHINE ALLOW TEMPS TO REBOUND INTO 40S. OTHERWISE
NORTHWEST MID LEVEL FLOW AT MID WEEK WILL BE REPLACED BY WAVE/LOW
APPROACHING FOR THE END OF THE WEEK INTO THE WEEKEND. OFF-AND-ON
PRECIPITATION CHANCES WILL RESULT BEGINNING WEDNESDAY NIGHT...WITH
CLOUDS AND LITTLE IN THE WAY OF WARM/COLD ADVECTION SUGGESTING
TEMPERATURES WILL BE RANGE-BOUND IN THE 20S FOR LOWS AND 30S OR
LOWER 40S FOR HIGHS.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
328 AM CDT SUN MAR 17 2013
.DISCUSSION...
THE CHANCE FOR RAIN AND SNOW TONIGHT THEN WINDS BEHIND COLD FRONT
MONDAY ARE THE PRIMARY FORECAST CONCERNS.
A COUPLE OF AREAS OF PRECIPITATION WERE IN OR NEAR OUR CWA THIS
MORNING. LIGHT SNOW MOVED FROM NORTH CENTRAL INTO NORTHEAST NEBRASKA
DURING THE LATE EVENING...DROPPING A DUSTING TO A HALF INCH OF SNOW
FOR SOME OF OUR NORTHERN AREAS. THIS SEEMED TO BE TIED TO 90-120KT
300MB JET STRETCHING FROM NORTHERN NEBRASKA INTO THE GREAT LAKES.
WITH THAT JET SHIFTING EAST THIS MORNING...THINK ANY LINGERING SNOW
SHOWERS WILL BE SHORT-LIVED AFTER SUNRISE. SHORT RANGE MODELS RAP
AND HRRR CONCUR. THE SECOND AREA OF PRECIPITATION WAS STAYING MOSTLY
SOUTH OF THE CWA ACROSS NORTHERN KANSAS...AND LOOKED TO BE CAUSED BY
MID LEVEL WARM ADVECTION AHEAD OF 700MB SHORTWAVE MIGRATING EAST
THROUGH KANSAS. A FEW RADAR RETURNS MOVED ACROSS THE SOUTHEAST
NEBRASKA BORDER...BUT TRENDS HAVE BEEN TO CONCENTRATE PRECIP JUST
SOUTH OF OUR AREA. SO ONLY SMALL CHANCES EARLY TODAY THERE...WITH
LIGHT SNOW THE MAIN PRECIP TYPE.
ATTENTION THEN TURNS TO STRONG MID LEVEL SHORTWAVE NOW DIVING
THROUGH WASHINGTON AND OREGON INTO IDAHO. THIS FEATURE WILL RACE
EAST AND STRENGTHEN TODAY...REACHING THE WESTERN DAKOTAS BY
00Z...WITH AXIS OF MID LEVEL TROUGH SWINGING THROUGH OUR AREA MONDAY
MORNING. STRONG SURFACE LOW WILL DEVELOP IN THE NORTHERN HIGH PLAINS
THROUGH THE DAY...THEN ROTATE THROUGH THE DAKOTAS OVERNIGHT WHILE
DRIVING A COLD FRONT THROUGH NEBRASKA AND WESTERN IOWA BY SUNRISE
MONDAY. SOUTHEAST TO SOUTH LOW LEVEL FLOW WILL DEVELOP IN OUR AREA
TODAY IN RESPONSE TO LOWERING PRESSURES TO OUR NORTHWEST...AND WILL
PUSH TEMPERATURES TOWARD 40 THIS AFTERNOON. MID LEVEL THETA-E
INCREASE IN DIFFLUENT FLOW REGIME AHEAD OF TROUGH WILL PROVIDE
SUFFICIENT MOISTURE/LIFT FOR PRECIPITATION AS EARLY AS THIS
AFTERNOON IN CENTRAL AND PERHAPS NORTHEAST NEBRASKA. BUT BETTER
CHANCES COME OVERNIGHT AHEAD OF SURFACE COLD FRONT UNDER CORE OF MID
LEVEL JET SEGMENT. HAVE KEPT PRECIPITATION CHANCES RELATIVELY
HIGH...WITH BEST CHANCES ACROSS THE NORTH NEARER BETTER COMBINATION
OF LIFT/MOISTURE.
PRECIPITATION TYPE CONTINUES TO BE AN ISSUE AS SURFACE LAYER REMAINS
ABOVE FREEZING UNTIL COLD FRONT ARRIVES. MODEL DEPICTIONS OF LAYER
TEMPERATURE PROFILES ARE NOT CONSISTENT WITH EACH OTHER...AND
TEMPERATURE TRENDS WITHIN THE SAME MODEL SPORADICALLY MOVE THERMAL
PROFILE FROM JUST ABOVE TO JUST BELOW FREEZING AND BACK AGAIN WITH
TIME. THIS IS LIKELY DUE TO DYNAMIC COOLING EFFECTS GIVEN VIGOROUS
BUT SMALL AREAS OF LIFT UNDER FAST FLOW. SO A VARIETY OF WEATHER
TYPES ARE POSSIBLE FROM TIME TO TIME OVERNIGHT...BUT WILL FOCUS THIS
FORECAST ON TIMING OF PREDOMINANT WEATHER TYPE CHANGING FROM MAINLY
RAIN TO MAINLY SNOW...AND LET POTENTIAL SNOW AMOUNTS FALL OUT OF
THAT THINKING.
THERMAL PROFILES WILL SUPPORT RAIN FROM LATE THIS AFTERNOON THROUGH
MID EVENING...WITH THICKNESS PROGS SUGGESTING A TRANSITION TOWARD
SNOW IN OUR NORTHWEST BY 03Z. THAT TREND WILL QUICKLY SWING EAST AND
SOUTHEAST THROUGH 06Z...WITH MAINLY SNOW EXPECTED IN OUR SOUTH AFTER
09Z. BETTER COOLING REGIME IS EXPECTED ACROSS OUR NORTH...SO HIGHER
POTENTIAL SNOW TOTALS THERE. HOWEVER...STRONG LIFT NEAR AND
NORTH/NORTHEAST OF THE OMAHA METRO AREA AROUND 06Z MAY END UP BEING
THE MAIN SNOW ZONE WITH THIS SYSTEM. AN ENSEMBLE APPROACH TO SNOW
AMOUNT FORECAST SUGGESTS 1 TO 2 INCHES WILL BE COMMON FROM NORTHEAST
NEBRASKA INTO WEST CENTRAL IOWA. THIS COMBINES STRAIGHT MODEL
OUTPUT...COBB CALCULATIONS OF SEVERAL MODELS...AND A GARCIA
MANIPULATION OF MIXING RATIOS TAKING INTO ACCOUNT 6 HOUR PERIOD OF
PRECIPITATION AND A TRANSITION FROM RAIN TO SNOW OCCURRING NEAR THE
MIDWAY POINT OF THE PRECIP.
FAST-MOVING SYSTEM SHOULD TAKE MOST PRECIPITATION EAST OF OUR WESTERN
IOWA COUNTIES BY 12Z MONDAY. STRONG WINDS WILL FOLLOW DURING THE DAY
AS UNIDIRECTIONAL NORTHWEST FLOW AND STRONG COLD ADVECTION POINT TO
EFFECTIVE TRANSFER OF MOMENTUM IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS STILL SHOW THE POTENTIAL FOR 40MPH WIND GUSTS ON MONDAY.
AND AM NOT EXPECTING A LOT OF WARMING MONDAY GIVEN COLD ADVECTION
DESPITE CLEARING SKIES. HAVE HIGHS GENERALLY IN THE 30S NORTH TO
LOWER 40S SOUTH.
THE REST OF THE WEEK STILL LOOKS TO BE COOL. TUESDAY MAY BE THE
WARMEST...OR LEAST COOL...DAY OF THE WEEK WHERE A RELATIVELY MILD
START AND SUNSHINE ALLOW TEMPS TO REBOUND INTO 40S. OTHERWISE
NORTHWEST MID LEVEL FLOW AT MID WEEK WILL BE REPLACED BY WAVE/LOW
APPROACHING FOR THE END OF THE WEEK INTO THE WEEKEND. OFF-AND-ON
PRECIPITATION CHANCES WILL RESULT BEGINNING WEDNESDAY NIGHT...WITH
CLOUDS AND LITTLE IN THE WAY OF WARM/COLD ADVECTION SUGGESTING
TEMPERATURES WILL BE RANGE-BOUND IN THE 20S FOR LOWS AND 30S OR
LOWER 40S FOR HIGHS.
DERGAN
&&
.AVIATION...06Z TAFS FOR KOMA...KLNK...KOFK.
CEILINGS WILL BE THE MAIN CONCERN THROUGH THE PERIOD. LOW CLOUDS
HAD SCATTERED OUT AT THE TAF SITES THIS EVENING...BUT SHOULD MOVE
BACK IN AT LEAST TEMPORARILY OVERNIGHT AND THROUGH MID MORNING
SUNDAY. EXPECT INCREASING SOUTHEAST WINDS AND GENERALLY VFR
CONDITIONS FROM LATE MORNING THROUGH MID AFTERNOON. MVFR CEILINGS
SHOULD MOVE BACK IN WITH NEXT SYSTEM APPROACHING. DID MENTION
POTENTIAL FOR A RAIN/SNOW MIX FOR KOMA AND KOFK SUNDAY EVENING...
BUT NOT FOR KLNK AT THIS TIME. PCPN TYPE WILL NEED TO BE ADJUSTED
AS THE EVENT GETS CLOSER...SINCE PCPN COULD CHANGE TO ALL SNOW...
ESPECIALLY AT KOFK.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
152 AM EDT SUN MAR 17 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE AREA OVERNIGHT BRINGING DRIER
AIR AND SO ONLY PATCHY FLURRIES. THE NEXT WEATHER MAKER FOR THE
AREA WILL BE A COMPLEX LOW PRESSURE SYSTEM OVER THE GREAT LAKES
AND MID ATLANTIC COAST MONDAY AND TUESDAY. THIS SYSTEM WILL BRING
SNOW OR MIXED PRECIPITATION TO THE AREA BEGINNING LATE MONDAY AND
CONTINUING INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1008 PM UPDATE...
LAST FLURRIES ARE TAPERING OFF ON SCHEDULE, AND IR SAT SHOWS THE
FORECAST CLEARING IS BEGINNING FROM NORTHWEST TO SOUTHEAST. HAVE
MADE SOME MINOR ADJUSTMENTS TO THE TEMPERATURE GRIDS, TIMING THE
FALL OFF COINCIDENT WITH THE RAPID CLEARING. EXISTING FORECAST
REMAINS IN VERY GOOD SHAPE.
610 PM UPDATE...
LIGHT SNOW SHOWERS ARE PROVING TO BE STUBBORN HEADING INTO THE
EVENING HOURS. AFTER CHECKING THE LATEST RAP FIELDS, DECIDED TO
KEEP CHC POPS AROUND FOR A FEW EXTRA HOURS THIS EVENING. GRIDS
LOOK TO BE IN GOOD SHAPE, SO JUST A MINOR UPDATE.
3 PM UPDATE...
BACK EDGE OF THE LGT SNOW MVG RAPIDLY ACROSS CNTRL PA ATTM
AND WILL BRING AN END TO THE SNOW QUICKLY THIS AFTN. HWVR...CRNTS
UPSTREAM SHOW PLENTY OF CLDS AND LL MOISTURE HANGING BACK ALONG
THE FNTL BNDRY. SO...DONT XPCT RAPID CLRG THIS EVE...AND A FEW LGT
FLURRIES COULD LINGER THRU THE NGT. FB RPTS HAVE BEEN ANYWHERE
FROM A TRACE TO TWO INCHES SO FAR...SO WITH THE BACK EDGE MVVG
RAPIDLY EAST...REALLY NO NEED FOR ANY FLAGS WITH THIS EVENT. TEMPS
THIS EVE WILL DROP INTO THE MID TEENS OR LWR IN MANY PLACES WITH
CAA BHD THE LOW. MODEL GUID IN GOOD AGREEMENT ON MINS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
SCNDRY TROF/COLD FNT PASSES EARLY SUN MRNG AND MAY BRING SOME LGT
SNOW SHWRS TO THE NRN ZONES. MUCH DRIER AIR BHD THIS TROF SHD
ALLOW FOR GRADUAL CLRG SUN AFTN...WITH LIMITED LAKE CLDS AND
FLURRIES DUE TO THE VERY DRY AIR AND WEAK INSTABILITY OFF THE COLD
LAKE.
1028MB HIGH SLIDES SLOWLY EAST INTO NEW ENG BY EARLY MON. THIS
WILL PROVIDE THE COLD AIR AND BAROCLINIC ZONE THAT HELP DEEPENTHE
SCNDRY LOW THAT DVLPS LATE MON. OLD LOW MVES WELL WEST INTO THE
WRN LAKES...BUT WITH THIS BLOCKING HI...COLD AIR WILL BE SLOW TO
LEAVE AND WILL BE REENFORCED BY THE DVLPG CSTL LOW. THIS WILL
ALLOW SNOW TO BRK OUT FROM WEST TO EAST LATE MON AND CONT INTO
EARLY TUE. INITIAL BURST OF WAA SNOW COULD BE MODERATELY HEAVY MON
EVE. NAM HAS NOW MVD INTO THE EURO/S CAMP AND KEEPS THE AREA
COLDER THRU THE EVENT. MODEL FCST PROFILES GNRLY SUPPORT ALL SNOW
NORTH OF THE NY/PA BRDR AND EAST OF I81. TO THE SOUTH AND
WEST...WRM LAYR SHD ALLOW A CHG TO FRZG RAIN...WITH THE COLD AIR
DAMMING...DOES NOT LOOK LIKE TEMOPS WILL GET ABC FRZG...EVEN OVER
NE PA...THRU 12Z TUE.
LOW WILL MVE RAPIDLY EAST SO THE CHANCE FOR WRAP ARND SNOW FROM
THE CSTL TUE WILL BE LIMITED. ATTM...SNOWFALL AND ANY ICE AMTS
LOOK TO BE PRETTY SOLIDLY IN THE ADVISORY CATEGORY WO WILL NOT BE
ISSUING ANY FLAGS AND JUST CONT THE MENTION IN THE HWO.
GNRLY FLWD THE COLDER NAM GUID FOR THE GRIDS AS THE GFS BASED MAV
SEEMED TOO WARM.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
2 PM SAT UPDATE...
FOLLOWED WPC GUIDANCE. COLDER THAN NORMAL WITH MORE SNOW SHOWERS.
MODELS ARE SIMILAR. A NOREASTER MOVES NE INTO EASTERN NEW ENGLAND
TUESDAY NIGHT BUT A LARGE UPPER LEVEL LOW REMAINS OVER THE
NORTHEAST US AT LEAST THROUGH FRIDAY. THIS TROF KEEPS THE BIG
STORMS TO THE S0UTH BUT WILL KEEP COLD AIR OVER THE AREA. IT WILL
BE COLD ENOUGH FOR LAKE ENHANCEMENT. SLOW WARMING LATE IN THE
WEEK.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE CONTINUES TO BUILD IN AND WILL BE IN CHARGE FOR THE
TAF PERIOD...WITH MAINLY VFR. THE EXCEPTION WILL BE THAT A WEAK
UPPER WAVE WILL PASS THROUGH DURING THE MORNING...WHICH ALONG WITH
COLD ENOUGH ATMOSPHERE TO YIELD SOME LAKE CLOUDS/LIGHT
FLURRIES...WILL PRODUCE SOME MVFR RESTRICTIONS WITHIN THE 08Z-17Z
WINDOW. SEE TAFS FOR SPECIFICS ON TIMING. AFTER 17Z ENOUGH DRY AIR
TO AT LEAST LIFT CIGS OUT OF MVFR AND EVEN SCATTER THEM OUT WITH
TIME. LIGHT FLOW AT OR BELOW 10 KTS WILL VEER FROM WNW TO NNW
TODAY...TO LIGHT NNE OR VRB THIS EVENING.
.OUTLOOK...
LATE SUN NIGHT THROUGH MON MRNG...MAINLY VFR.
MIDDAY MON TO TUE PM...DEVELOPING IFR RESTRICTIONS LIKELY IN SNOW
MON PM...TRANSITION TO MIXED PRECIP LATE MON NGT/TUE.
TUE NGT TO THU...MVFR/BRIEF IFR IN SCT SNOW SHWRS...MOSTLY IN NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...MDP
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
958 AM EDT SUN MAR 17 2013
.SYNOPSIS...
PRECIPITATION WILL SLOWLY OVER RUN A STALLED FRONTAL BOUNDARY IN
THE TENNESSEE VALLEY TODAY...AFFECTING SOUTHERN OHIO AND NORTHERN
KENTUCKY. AS A WAVE OF LOW PRESSURE EJECTS NORTHEAST FROM THE
SOUTHERN PLAINS INTO THE GREAT LAKES THE FRONT WILL ADVANCE SLOWLY
NORTHWARD TONIGHT AND MONDAY. THIS WILL INCREASE PRECIPITATION
CHANCES. SOME PLACES MAY SEE A PERIOD OF WINTRY MIX TODAY AND
TONIGHT PRIOR TO CHANGING TO RAIN AS WARMER AIR MOVES INTO THE
REGION. A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG WITH A
SIGNIFICANT RAIN EVENT BEFORE AN ASSOCIATED COLD FRONT FINALLY
MOVES EAST OF THE REGION MONDAY NIGHT. CHILLY HIGH PRESSURE WILL
FOLLOW.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO DROP SOME OF THE NORTHERN TIER OF COUNTIES FROM
ADVISORY.
PREV DISCUSSION:
BAND OF HEAVIER PCPN HAS SET UP ALONG THE OHIO RIVER OVER AND ON
INTO FAR SOUTH CENTRAL OHIO. PCPN HAS GENERALLY SWITCHED OVER TO
ALL SNOW ACROSS OUR AREA. WE ARE STARTING TO GET SOME LIGHT
ACCUMULATIONS PRIMARILY ON GRASSY/EXPOSED SURFACES ACROSS NORTHERN
KENTUCKY AND HAVE EVEN AD A REPORT OF 1 INCH IN ROBERSON COUNTY.
THE NORTHERN EXTENT OF THE PCPN IS THE BIGGEST CONCERN AT THIS
POINT AS OUR NORTHERN TIER OF ADVISORY COUNTIES APPEAR TO BE ON
THE NORTHERN FRINGE. HOWEVER...THE LAST FEW RUNS OF THE RAP ARE
TRYING TO BRING AN ENHANCED BAND OF PCPN UP ACROSS THOSE COUNTIES
THROUGH LATE MORNING AND WE MAY BE BEGINNING TO SEE THAT FORMING
NOW ON RADAR OVER EAST CENTRAL INDIANA. AS A RESULT...WILL LIKELY
SIT TIGHT ON THE ADVISORY AT THE MOMENT AND SEE HOW THINGS DEVELOP
OVER THE NEXT HOUR OR SO...BUT IF THIS FAILS TO MATERIALIZE WILL
PROBABLY NEED TO TRIM BACK SOME OF THE NORTHERN COUNTIES FROM THE
ADVISORY. ELSEWHERE...SOME 1 TO LOCALLY 2 INCH ACCUMULATIONS WILL
BE POSSIBLE ON EXPOSED AND GRASSY SURFACES BUT IMPACT WISE...DO
NOT EXPECT MUCH OF AN ISSUE AS ROAD TEMPERATURES ARE STILL RUNNING
WELL INTO THE 40S ACROSS THE ADVISORY AREA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
UPPER LEVEL FLOW BACKS TONIGHT AHD OF TROF MOVING INTO THE
PLAINS. SFC LOW PRES TO EJECT NE INTO THE LOWER OH VLY BY 12Z
MONDAY. FAVORABLE ISENTROPIC LIFT ASSOCIATED WITH STRENGTHENING 50
KT LLJ ALLOWS PCPN TO OVERSPREAD THE ENTIRE FA. BEST LIFT COMES
INTO PLAY BETWEEN 06Z AND 12Z. AS THIS PRECIP ENCOUNTERS COLDER
AIR A WINTRY MIX WILL SPREAD NORTH TO SOUTH. UNDER THE INFLUENCE
OF WAA THE WINTRY MIX WILL BE LIMITED WITH A CHANGE OVER TO ALL
RAIN MONDAY MORNING. EXPECT LOWS TO RANGE FROM THE LOWER 30S NW TO
THE MID 30S SOUTH.
SFC WAVE TO TO LIFT NE FROM THE LWR OHIO VALLEY INTO THE SRN GREAT
LAKES WITH ASSOCIATED COLD FRONT SWEEPING EAST THRU ILN/S FA BY
MONDAY EVENING. FAVORABLE MOISTURE TRANSPORT WILL EXIST WITH PW/S
INCREASING TO ABOVE 1 INCH ACRS THE SOUTH. THESE VALUES ARE ABOUT
200 PERCENT OF NORMAL. THE SE HALF OF THE FA GETS INTO THE WARM
SECTOR WITH FAVORABLE INSTBY INDICATED WILL MENTION A CHC OF
THUNDER WITH MODERATE RAIN. THIS RAINFALL CUD LEAD TO LOCALIZED
FLOODING THREAT...ESPECIALLY IN THE LICKING...LITTLE MIAMI...OHIO
BRUSH CREEK AND LOWER SCIOTO BASINS. THERE WILL BE A GOOD
TEMPERATURE GRADIENT WITH MONDAYS HIGHS RANGING FROM THE MID 40S
NW TO NEAR 60 SE.
UPPER TROF TO SETTLE INTO SETTLE THE NRN GREAT LAKES WITH NW FLO
DEVELOPING ACRS THE OHIO VLY. SYSTEM IS PROGRESSIVE WITH COLD
FRONT SWEEPING TO THE EAST. HAVE ENDED PCPN A LTL QUICKER WITH A
CHANGE OVER TO SNOW PRIOR TO ENDING LATE MONDAY NIGHT. THIS
QUICKER ENDING WILL LIMIT ANY PSBL ACCUMULATION. LOWS WILL RANGE
FROM THE LOWER 20S NW TO THE LOWER 30S SE. COLD HIGH PRESSURE TO
NOSE IN ON TUESDAY. HIGHS TUESDAY WILL BE 10 TO 12 DEGREES BELOW
NORMAL...RANGING FROM THE MID/UPR 30S NORTH TO THE MID 40S SOUTH.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THERE ARE SOME INDICATIONS THAT A SHORT WAVE DROPPING ACROSS THE
REGION ON WEDNESDAY COULD PRODUCE SOME LIGHT PRECIPITATION. BUT
UNCERTAINTIES IN TIMING...PLACEMENT AND STRENGTH PRECLUDE POPS
ABOVE THRESHOLD AT THIS TIME. OTHERWISE THE LONG TERM PERIOD WILL
BE DRY WITH PERSISTENT BELOW NORMAL TEMPERATURES. RIDGING AT THE
SURFACE WITH UPPER LEVEL NORTHWEST FLOW WILL PREDOMINATE.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
MODEL UNCERTAINTY AND BORDERLINE TEMPERATURES CONTRIBUTE TO A LACK
OF CONFIDENCE IN THIS FORECAST. A BAND OF PRECIPITATION ALONG A
SLOW MOVING FRONTAL BOUNDARY WILL AFFECT SOUTHERN TAF SITES CVG
LUK AND TO A LESSER EXTENT ILN. SNOW MIXING WITH RAIN IS EXPECTED
TO DEVELOP THERE WITH VISIBILITIES FALLING AS LOW AS IFR AT CVG
AND LUK. MAIN EFFECTS SHOULD OCCUR LATE MORNING THROUGH EARLY
AFTERNOON. DAY CMH AND LCK WILL CONTINUE TO HAVE MVFR CEILINGS BUT
PROBABLY NO PRECIP THROUGH THIS AFTERNOON.
MODERATE RAIN WILL OVERSPREAD ALL SITES TONIGHT AS A WAVE OF LOW
PRESSURE TRAVELING ALONG THE FRONT BRINGS WARMER TEMPERATURES AND
A WIDE AREA OF PRECIPITATION. WINDS WILL SHIFT FROM NORTH TO EAST
WITH GUSTS TO 20 KNOTS POSSIBLE AT SOUTHERN SITES LATE IN THE
PERIOD. FOR CVG ON MONDAY...RAIN IS EXPECTED TO END MID
MORNING...WITH WINDS SHIFTING TO SOUTHWEST.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES ARE LIKELY MONDAY
INTO TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR OHZ078-
079-081-082-088.
KY...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR
KYZ089>100.
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR INZ075-
080.
&&
$$
SYNOPSIS...AR
NEAR TERM...JGL
SHORT TERM...AR
LONG TERM...
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
906 AM EDT SUN MAR 17 2013
.SYNOPSIS...
PRECIPITATION WILL SLOWLY OVER RUN A STALLED FRONTAL BOUNDARY IN
THE TENNESSEE VALLEY TODAY...AFFECTING SOUTHERN OHIO AND NORTHERN
KENTUCKY. AS A WAVE OF LOW PRESSURE EJECTS NORTHEAST FROM THE
SOUTHERN PLAINS INTO THE GREAT LAKES THE FRONT WILL ADVANCE SLOWLY
NORTHWARD TONIGHT AND MONDAY. THIS WILL INCREASE PRECIPITATION
CHANCES. SOME PLACES MAY SEE A PERIOD OF WINTRY MIX TODAY AND
TONIGHT PRIOR TO CHANGING TO RAIN AS WARMER AIR MOVES INTO THE
REGION. A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG WITH A
SIGNIFICANT RAIN EVENT BEFORE AN ASSOCIATED COLD FRONT FINALLY
MOVES EAST OF THE REGION MONDAY NIGHT. CHILLY HIGH PRESSURE WILL
FOLLOW.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BAND OF HEAVIER PCPN HAS SET UP ALONG THE OHIO RIVER OVER AND ON
INTO FAR SOUTH CENTRAL OHIO. PCPN HAS GENERALLY SWITCHED OVER TO
ALL SNOW ACROSS OUR AREA. WE ARE STARTING TO GET SOME LIGHT
ACCUMULATIONS PRIMARILY ON GRASSY/EXPOSED SURFACES ACROSS NORTHERN
KENTUCKY AND HAVE EVEN AD A REPORT OF 1 INCH IN ROBERSON COUNTY.
THE NORTHERN EXTENT OF THE PCPN IS THE BIGGEST CONCERN AT THIS
POINT AS OUR NORTHERN TIER OF ADVISORY COUNTIES APPEAR TO BE ON
THE NORTHERN FRINGE. HOWEVER...THE LAST FEW RUNS OF THE RAP ARE TRYING
TO BRING AN ENHANCED BAND OF PCPN UP ACROSS THOSE COUNTIES THROUGH
LATE MORNING AND WE MAY BE BEGINNING TO SEE THAT FORMING NOW ON
RADAR OVER EAST CENTRAL INDIANA. AS A RESULT...WILL LIKELY SIT
TIGHT ON THE ADVISORY AT THE MOMENT AND SEE HOW THINGS DEVELOP
OVER THE NEXT HOUR OR SO...BUT IF THIS FAILS TO MATERIALIZE WILL
PROBABLY NEED TO TRIM BACK SOME OF THE NORTHERN COUNTIES FROM THE
ADVISORY. ELSEWHERE...SOME 1 TO LOCALLY 2 INCH ACCUMULATIONS WILL
BE POSSIBLE ON EXPOSED AND GRASSY SURFACES BUT IMPACT WISE...DO
NOT EXPECT MUCH OF AN ISSUE AS ROAD TEMPERATURES ARE STILL RUNNING
WELL INTO THE 40S ACROSS THE ADVISORY AREA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
UPPER LEVEL FLOW BACKS TONIGHT AHD OF TROF MOVING INTO THE
PLAINS. SFC LOW PRES TO EJECT NE INTO THE LOWER OH VLY BY 12Z
MONDAY. FAVORABLE ISENTROPIC LIFT ASSOCIATED WITH STRENGTHENING 50
KT LLJ ALLOWS PCPN TO OVERSPREAD THE ENTIRE FA. BEST LIFT COMES
INTO PLAY BETWEEN 06Z AND 12Z. AS THIS PRECIP ENCOUNTERS COLDER
AIR A WINTRY MIX WILL SPREAD NORTH TO SOUTH. UNDER THE INFLUENCE
OF WAA THE WINTRY MIX WILL BE LIMITED WITH A CHANGE OVER TO ALL
RAIN MONDAY MORNING. EXPECT LOWS TO RANGE FROM THE LOWER 30S NW TO
THE MID 30S SOUTH.
SFC WAVE TO TO LIFT NE FROM THE LWR OHIO VALLEY INTO THE SRN GREAT
LAKES WITH ASSOCIATED COLD FRONT SWEEPING EAST THRU ILN/S FA BY
MONDAY EVENING. FAVORABLE MOISTURE TRANSPORT WILL EXIST WITH PW/S
INCREASING TO ABOVE 1 INCH ACRS THE SOUTH. THESE VALUES ARE ABOUT
200 PERCENT OF NORMAL. THE SE HALF OF THE FA GETS INTO THE WARM
SECTOR WITH FAVORABLE INSTBY INDICATED WILL MENTION A CHC OF
THUNDER WITH MODERATE RAIN. THIS RAINFALL CUD LEAD TO LOCALIZED
FLOODING THREAT...ESPECIALLY IN THE LICKING...LITTLE MIAMI...OHIO
BRUSH CREEK AND LOWER SCIOTO BASINS. THERE WILL BE A GOOD
TEMPERATURE GRADIENT WITH MONDAYS HIGHS RANGING FROM THE MID 40S
NW TO NEAR 60 SE.
UPPER TROF TO SETTLE INTO SETTLE THE NRN GREAT LAKES WITH NW FLO
DEVELOPING ACRS THE OHIO VLY. SYSTEM IS PROGRESSIVE WITH COLD
FRONT SWEEPING TO THE EAST. HAVE ENDED PCPN A LTL QUICKER WITH A
CHANGE OVER TO SNOW PRIOR TO ENDING LATE MONDAY NIGHT. THIS
QUICKER ENDING WILL LIMIT ANY PSBL ACCUMULATION. LOWS WILL RANGE
FROM THE LOWER 20S NW TO THE LOWER 30S SE. COLD HIGH PRESSURE TO
NOSE IN ON TUESDAY. HIGHS TUESDAY WILL BE 10 TO 12 DEGREES BELOW
NORMAL...RANGING FROM THE MID/UPR 30S NORTH TO THE MID 40S SOUTH.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THERE ARE SOME INDICATIONS THAT A SHORT WAVE DROPPING ACROSS THE
REGION ON WEDNESDAY COULD PRODUCE SOME LIGHT PRECIPITATION. BUT
UNCERTAINTIES IN TIMING...PLACEMENT AND STRENGTH PRECLUDE POPS
ABOVE THRESHOLD AT THIS TIME. OTHERWISE THE LONG TERM PERIOD WILL
BE DRY WITH PERSISTENT BELOW NORMAL TEMPERATURES. RIDGING AT THE
SURFACE WITH UPPER LEVEL NORTHWEST FLOW WILL PREDOMINATE.
&&
.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
MODEL UNCERTAINTY AND BORDERLINE TEMPERATURES CONTRIBUTE TO A LACK
OF CONFIDENCE IN THIS FORECAST. A BAND OF PRECIPITATION ALONG A
SLOW MOVING FRONTAL BOUNDARY WILL AFFECT SOUTHERN TAF SITES CVG
LUK AND TO A LESSER EXTENT ILN. SNOW MIXING WITH RAIN IS EXPECTED
TO DEVELOP THERE WITH VISIBILITIES FALLING AS LOW AS IFR AT CVG
AND LUK. MAIN EFFECTS SHOULD OCCUR LATE MORNING THROUGH EARLY
AFTERNOON. DAY CMH AND LCK WILL CONTINUE TO HAVE MVFR CEILINGS BUT
PROBABLY NO PRECIP THROUGH THIS AFTERNOON.
MODERATE RAIN WILL OVERSPREAD ALL SITES TONIGHT AS A WAVE OF LOW
PRESSURE TRAVELING ALONG THE FRONT BRINGS WARMER TEMPERATURES AND
A WIDE AREA OF PRECIPITATION. WINDS WILL SHIFT FROM NORTH TO EAST
WITH GUSTS TO 20 KNOTS POSSIBLE AT SOUTHERN SITES LATE IN THE
PERIOD. FOR CVG ON MONDAY...RAIN IS EXPECTED TO END MID
MORNING...WITH WINDS SHIFTING TO SOUTHWEST.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES ARE LIKELY MONDAY
INTO TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR
OHZ070>072-077>082-088.
KY...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR
KYZ089>100.
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR INZ066-
073>075-080.
&&
$$
SYNOPSIS...AR
NEAR TERM...JGL
SHORT TERM...AR
LONG TERM...
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
808 PM EDT MON MAR 18 2013
.SYNOPSIS...
A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION TONIGHT...USHERING
IN DRY AIR FOR TUESDAY THROUGH THURSDAY. EXPECT UNSETTLED WEATHER TO
RETURN TO THE SOUTHEAST STATES THIS WEEKEND AND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 755 PM...LARGE AREA OF MODERATE/HEAVY RAIN WITH EMBEDDED TS
CONTINUES TO MOVE ACROSS THE AREA THIS EVENING. THE DEEPER
CONVECTION APPEARS TO BE SHIFTING TO AREAS EAST OF I-85...SO THE
THUNDER MENTION HAS BEEN TEMPERED SOMEWHAT ACROSS MUCH OF THE NC
ZONES. THE HEAVIER RAIN RATES ASSOCIATED WITH THE CONVECTION IS
RESULTING IN RAINFALL TOTALS AVERAGING QUITE A BIT HIGHER THAN
EARLIER FORECASTS...AND IT APPEARS MOST AREAS SOUTH OF THE I-40
CORRIDOR WILL SEE STORM TOTALS OF .50 TO .75 INCH. IN TERMS OF THE
SEVERE THREAT...THE SUPERCELLULAR CONVECTION THAT PRODUCED LARGE
HAIL IN THE ATLANTA METRO AREA EARLIER THIS EVENING HAS CONSOLIDATED
INTO A ROBUST QLCS THAT IS POISED TO MARCH ACROSS THE SC MIDLANDS
THROUGH THE DURATION OF THE EVENING. MEANWHILE...THE AIR MASS OVER
THE WESTERN CAROLINAS IS DOMINATED BY STABLE BOUNDARY LAYER AIR
ASSOCIATED WITH COLD AIR DAMMING. THE ONGOING ELEVATED CONVECTION
WILL POSE A MARGINAL LARGE HAIL THREAT...MAINLY EAST OF I-85 FOR THE
NEXT COUPLE OF HOURS...BUT THE SEVERE WEATHER THREAT IS WANING
RATHER QUICKLY FOR THE GSP CWA.
AS OF 445 PM...THE MAIN ALTERATION TO THE FORECAST WAS TO EXPAND
POPS EAST ACROSS THE CWFA MUCH QUICKER THAN PREVIOUSLY FORECAST...AS
NUMEROUS SHOWERS NOW EXTEND AS FAR EAST AS I-77. THERE IS ALSO A
DECENT AMOUNT OF ELEVATED INSTABILITY ACROSS THE WESTERN ZONES...AS
EVIDENCED BY MUCAPE APPROACHING 500 J/KG PER SPC MESOANALYSIS. THIS
IS RESULTING IN SCATTERED TO NUMEROUS TS ACROSS THE WESTERN HALF OF
THE AREA. THEREFORE...WE HAVE BEEFED UP THE TS MENTION FOR ALL AREAS
IN THE FORECAST SUITE FOR THE REMAINDER OF THE AFTERNOON/EVENING. WE
ARE SEEING PLENTY OF DISCRETE CELLS ACROSS THE TENN VALLEY... SOME
WITH MINI-SUPERCELL STRUCTURES. HOWEVER...THE WEDGE BOUNDARY HAS NOT
MADE MUCH NORTHWARD PROGRESS ACROSS THE CAROLINAS/NORTH GEORGIA OVER
THE LAST FEW HOURS. WE WILL HAVE TO CLOSELY MONITOR THE PROGRESS OF
THIS BOUNDARY WITH TIME...AS ANY PROGRESSION INTO OUR SOUTHERN ZONES
WILL POSE AN INCREASED CONCERN FOR SEVERE WEATHER. EVEN A TORNADO IS
POSSIBLE WITH ANY MINI-SUPERCELLS INTERACTING WITH THE BOUNDARY. THE
SECOND AREA OF CONCERN WILL BE WITH THE QLCS APPROACHING THE
SOUTHWEST MTNS...WHERE THERE APPEARS TO BE A BIT MORE IN THE WAY OF
BOUNDARY LAYER ROOTED INSTABILITY. EVERYWHERE ELSE...SEVERE WEATHER
CONCERNS SHOULD BE LIMITED TO PERHAPS AN ISOLATED HAIL THREAT.
AS OF 230 PM ...THE WEDGE CONTINUES TO HOLD FIRM WITH LOWS CLOUDS
AND AREAS OF MAINLY DRIZZLE EAST OF THE MOUNTAINS. RADAR IS SHOWING
SHOWERS BECOMING MORE WIDESPREAD OVER THE MOUNTAINS...AND A FEW
THUNDERSTORMS MAY ALSO HOLD TOGETHER TO AFFECT FAR WESTERN NC AND
THE THE TN BORDER COUNTIES BY 4 PM. THIS IS ALL HANDLED WELL IN THE
GRIDS AT THE MOMENT. TEMPS REMAIN QUITE COOL WITH LOW TO MID 40S
WIDESPREAD...EXCEPT SOME LOW TO MID 50S ON THE FRINGES OF THE WEDGE
IN THE FAR W AND S.
MODELS INDICATE THAT THE WEDGE WILL HOLD TOUGH AT LEAST THROUGH 06Z
AND REALLY NOT WASH OUT UNTIL AFTER THE PASSAGE OF A COLD FRONT
BEGINNING AROUND MIDNIGHT IN THE MOUNTAINS...AND LATE TONIGHT IN THE
FAR EASTERN COUNTIES. MESO MODELS LIKE THE HRRR AND OUR LOCAL WRF
INDICATE THAT THE MAIN AREA OF SHOWERS ASSOCIATED WITH A PASSING
UPPER WAVE WILL AFFECT THE AREA FROM MID AFTERNOON INTO EARLY
EVENING AND THEN SHIFT TO THE EAST OF THE AREA. ANOTHER BAND OF
SHOWERS IS THEN FORECAST TO ACCOMPANY THE COLD FRONT...BUT MAY BE
MORE SCATTERED EAST OF THE MOUNTAINS. SBCAPES REMAIN QUITE LOW OR
NON-EXISTENT DUE TO THE WEDGE...BUT MUCAPES APPEAR SUFFICIENT FOR
SOME ELEVATED THUNDER ALONG THE SOUTHERN AND WESTERN BOUNDARIES OF
THE WEDGE MODIFIED AIR. TEMPERATURES OVERNIGHT WILL REMAIN GENERALLY
STEADY OR EVEN SLOWLY RISE AS WEDGE SLOWLY ERODES. USED A BLEND OF 3
HOURLY MOS NUMBERS TO TRY AND CAPTURE THE TEMP TREND.
DEEP LAYER DRYING IS FORECAST TO OCCUR ON TUE BEHIND THE COLD FRONT
AS THE UPPER FLOW BECOMES ZONAL BEHIND THE DEPARTING UPPER WAVE AND
SURFACE HIGH PRESSURE RIDGES EAST. DOWNSLOPE FLOW ON TUE WILL
COUNTER COLD ADVECTION TO A LARGE EXTENT...AND WITH PLENTY OF
SUNSHINE TEMPS ARE FORECAST TO CLIMB WELL INTO THE 60S OUTSIDE THE
MOUNTAINS...WITH 50S IN THE MOUNTAIN VALLEYS. USED MOS BLEND TO
GENERATE TEMPS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 250 PM MONDAY...MODELS CONTINUE TO SHOW A CHANNELED SHORT WAVE
ROTATING AROUND A LARGE UPR LVL VORTEX OVR THE GREAT LAKES/SRN
QUEBEC LATE WED AND WED NITE. THE GUIDANCE ALSO HAS A WEAKER SHORT
WAVE MOVING ALONG THE GULF COAST DURING THIS TIME. AT THE SFC...
THESE WAVES LEAD TO A DOUBLE-BARRELED LOW PRESSURE SYSTEM...ONE NRN
STREAM CLIPPER AND A SRN STREAM FAST MOVING GULF COAST LOW. SOME OF
THE GUIDANCE IS NOW DEVELOPING LIGHT PRECIP WITH THE SRN STREAM LOW.
HOWEVER...THE LOW LEVELS REMAIN QUITE DRY...SO EXPECT NO MORE THAN
MOSTLY CLOUDY SKIES FROM MAINLY MID AND HIGH LEVEL CLOUDS. MDLS
STILL SHOWING THE NRN STREAM CLIPPER PRODUCING LIGHT PRECIP ACROSS
MAINLY THE TN BORDER COUNTIES OF THE NC MTNS. TEMPS AND THICKNESSES
HAVE COME IN QUITE COLDER WITH THESE SYSTEMS. THEREFORE...IT APPEARS
THAT ANY PRECIP ACROSS THE MTNS WILL BE MAINLY SNOW SHOWERS...
POSSIBLY MIXED WITH RAIN AT ONSET. GUIDANCE BLEND OF QPF SUGGESTING
UP TO AN INCH OF SNOW POSSIBLE ACROSS THE USUAL AREAS OF THE NRN
MTNS. IF SOMETHING WAS TO FALL OUTSIDE OF THE MTNS...IT WOULD BE
SPRINKLES OR FLURRIES. SUSTAINED WINDS HAVE COME IN LOWER ON THE
LATEST GUIDANCE FOR WED...BUT IT SHOULD STILL BE BREEZY WITH GUSTY
WINDS.
LOWS TUE NITE 5 TO 10 DEGREES BELOW NORMAL ACROSS THE MTNS AND A FEW
DEGREES BELOW NORMAL ELSEWHERE. THE 20TH IS THE FIRST DAY OF SPRING
WHICH IS THE START OF THE FROST/FREEZE PROGRAM OUTSIDE OF THE MTNS
FOR OUR CWFA. I DO HAVE SOME AREAS AROUND FREEZING. HOWEVER...WILL
HOLD OFF ON A FREEZE WATCH AS THERE WILL BE QUITE A BIT OF MID AND
HIGH CLOUDS THAT SHUD KEEP TEMPS FROM FALLING DRAMATICALLY. HIGHS
WED AROUND 5 DEGREES BELOW NORMAL
SKIES CLEAR OUTSIDE OF THE MTNS LATE WED NITE AND OVER THE MTNS THU.
LOWS AROUND 10 DEGREES BELOW NORMAL. SHUD THIS TREND CONTINUE...THEN
A FREEZE WARNING WOULD BE NEEDED FOR MUCH OF THE CWFA OUTSIDE OF THE
MTNS. LOOKS TO BE A BREEZY AND POSSIBLY WINDY DAY THU WITH GUSTY
WINDS AGAIN. HIGHS WILL BE 10 TO 15 DEGREES BELOW NORMAL WITH THE
COLD AIR MASS MOVING IN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 220 PM TUESDAY...DIFFERENCES SEEN IN THE MEDIUM RANGE MODELS
IN TIMING AND LOCATION OF LOW DEVELOPMENT. THIS PERIOD BEGINS AT 00Z
FRIDAY AND AT THAT TIME THE GFS AND ECMWF AGREE ON LOCATION OF UPPER
LOW OVER QUEBEC AND THE DEPARTING WEAK SURFACE HIGH OVER THE
CAROLINAS. FAIRLY GOOD INFLOW FROM THE GULF ON FRIDAY AHEAD OF THE
LOW OVER EAST TEXAS. ALTHOUGH THERE IS SOME GENERAL AGREEMENT ON
LOWS CROSSING THE SOUTHEAST STATES...THE CANADIAN IS CLOSER TO THE
ECMWF AND THE GFS CREATES A VASTLY DIFFERENT SOLUTION ON THE LOW
DEVELOPMENT OVER TENNESSEE SATURDAY NIGHT INTO SUNDAY. THE GFS SETS
UP A BETTER COLD AIR WEDGE SATURDAY INTO SATURDAY
NIGHT...HOWEVER...THE CENTER OF THE HIGH WILL BE FAR NORTH IN
CANADA. THE GFS DEVELOPS A DEEP LOW NEAR MEMPHIS LATE SATURDAY AND
TRACKS IT EAST CROSSING THE NC MTNS LATE SUNDAY. KEEPING A DIURNAL
PRECIP TRANSITION FOR THE MTNS AND NC FOOTHILLS WITH NIGHT TIME SNOW
AND DAYTIME RAIN AS SOUNDINGS TRENDING TOWARD EITHER RAIN OR SNOW.
BOTH GFS AND ECMWF DEVELOP AND COASTAL LOW TO START THE NEW WEEK
WITH THE FIRST LOW GIVING ITS ENERGY TO THE NEW LOW ON THE NC COAST
AND THIS MOVES EAST OVER THE ATLANTIC. DRYING TO OCCUR AT THE END OF
THE CURRENT SEVEN DAY WITH HIGH PRESSURE CROSSING THE PLAINS.
DAYTIME HIGHS THROUGH THIS MEDIUM RANGE AT LEAST TEN DEGREES BELOW
NORMAL AND NIGHT TIME LOWS 2 TO 5 DEGREES BELOW NORMAL DUE TO THE
CLOUD COVER.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...TS ACTIVITY IS GRADUALLY DIMINISHING ACROSS
THE AREA...BUT WILL BE POSSIBLE...ALONG WITH HEAVY RAIN...FOR THE
FIRST COUPLE OF HOURS OF THE PERIOD AT KCLT AND THE UPSTATE SC
TERMINALS. A FEW SITES HAVE REPORTED GUSTY N/NW WINDS WITH THE TS...
BUT THIS SHOULD BECOME LESS LIKELY AT THE TERMINALS. CONVECTION HAS
OCCASIONALLY BEEN ASSOCIATED WITH CIGS LIFTING TO MVFR OR EVEN
VFR...ESP IN THE MTNS AND FOOTHILLS. THIS MAY ALSO OCCUR AT KAND/
KCLT OVER THE FIRST COUPLE OF HOURS OF THE FORECAST PERIOD.
HOWEVER...CIGS SHOULD EVENTUALLY RETURN TO IFR/LIFR AS THE HEAVIER
RAIN GIVES WAY TO LIGHT PRECIP BY MID-EVENING. ALL TERMINALS SHOULD
EVENTUALLY SEE LIFR CIGS (EXCEPT PERHAPS KAVL...WHICH MAY TEND
TOWARD THE IFR/MVFR SPECTRUM) LASTING THROUGH THE OVERNIGHT. VISBY
IS ALSO EXPECTED TO BECOME MORE OF A CONCERN LATE TONIGHT AS THE
COLD AIR DAMMING AIR MASS BECOMES SHALLOWER AND CONDITIONS BEGIN TO
DRY OUT ALOFT. RAPID IMPROVEMENT IS EXPECTED AFTER SUNRISE TUESDAY
MORNING AS A COLD FRONT MOVES ACROSS THE AREA...SHIFTING WINDS TO A
DRYING NORTHWEST FLOW. SOME GUSTS NEAR 20 KT WILL BE POSSIBLE
TUESDAY MORNING THROUGH EARLY AFTERNOON...ESP AT KAVL.
OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH THURSDAY...
WITH A RETURN TO AN UNSETTLED PATTERN EXPECTED BY THE END OF THE
WEEK.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-24Z
KCLT MED 76% HIGH 82% HIGH 96% HIGH 100%
KGSP HIGH 87% MED 77% HIGH 96% HIGH 100%
KAVL MED 67% HIGH 83% HIGH 97% HIGH 100%
KHKY HIGH 82% MED 77% HIGH 94% HIGH 100%
KGMU HIGH 87% MED 77% HIGH 97% HIGH 100%
KAND MED 69% MED 74% HIGH 94% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.FIRE WEATHER...
A WARM...DRY AND WINDY AIR MASS WILL MOVE IN TUE BEHIND A DEPARTING
COLD FRONT. MINIMUM RH VALUES WILL BE LESS THAN 25 PERCENT ACROSS
MUCH OF THE AREA WITH GUSTY WINDS DEVELOPING. ALTHOUGH FUEL MOISTURE
IS RELATIVELY HIGH AND PRECIP MOVES ACROSS THE AREA TONIGHT...NC
FOREST SERVICE IS CONCERNED ABOUT THE DRYING AND DEVELOPING WINDS.
THEREFORE...A FIRE DANGER STATEMENT WILL BE ISSUED FOR TUE. SC LAND
MANAGERS ARE NOT AS CONCERNED FOR THE UPSTATE AND NE GA FUEL
MOISTURE WAS NEAR 20 PERCENT MON AFTERNOON. THEREFORE...NO STATEMENT
FOR SC OR GA. BREEZY AND GUSTY CONDITIONS RETURN WED AFTERNOON WITH
ANOTHER DAY OF VERY LOW RH VALUES. FIRE DANGER STATEMENTS MAY BE
NEEDED THEN AS WELL.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...JDL/LG
SHORT TERM...RWH
LONG TERM...DEO
AVIATION...JDL
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
435 PM EDT SUN MAR 17 2013
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE NORTH CAROLINA...SOUTH CAROLINA BORDER
WILL SLOWLY MEANDER ACROSS THE FORECAST AREA THIS EVENING. MEANWHILE
A SECONDARY COLD FRONT WILL SWEEP ACROSS THE DEEP SOUTH ON TUESDAY
ALLOWING COLDER AIR TO FILTER IN BEHIND IT ON WEDNESDAY. COOL HIGH PRESSURE
WILL REMAIN ACROSS THE AREA INTO FRIDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
430 PM UPDATE...REVISED TEMP/DEWPT TRENDS A BIT TO BETTER REFLECT
FRONTAL POSITIONING. FRONTAL BOUNDARY STILL MAKING SLOW SWD PROGRESS
ON TCLT IMGY AND COOLING TREND LIKELY HAS ALREADY STARTED NORTH OF
THE BDY...WHILE SITES WEST/SOUTH OF IT WILL REMAIN FAIRLY STEADY FOR
ANOTHER HR OR TWO. DELAYED SCHC POPS IN NRN MTNS UNTIL EARLY EVENING
AS CONVECTIVE TRENDS ON SATELLITE IMGY NOT ESPECIALLY IMPRESSIVE
THERE DESPITE HAVING A SMALL AMOUNT OF MUCAPE SHOWN ON SPC
MESOANALYSIS.
AS OF 300 PM SUN...THE TCLT RADAR SHOWS THE NASCENT WEDGE BOUNDARY
PUSHING SW ACROSS THE PIEDMONT INTO THE CHARLOTTE METRO
AREA...RUNNING OUT AHEAD OF THE LOWER CLOUDS WHICH ARE THINNING
ACROSS THE NW PIEDMONT. THE BOUNDARY MIGHT FIND IT DIFFICULT MOVING
MUCH FARTHER INTO AN AIR MASS THAT IS BEING HEATED FROM ABOVE... SO
EXPECT IT TO STALL BEFORE RESUMING ITS SW DRIFT AROUND SUNSET.
THAT WILL BEGIN A COLD AIR DAMMING EVENT AS A STRENGTHENING SFC HIGH
SLIDES INTO POSITION OVER NEW ENGLAND THIS EVENING AND LOW PRESSURE
MOVES ACROSS THE MID MS VALLEY. THE SET UP IS SOMEWHAT CLASSIC WITH
A CONFLUENT UPPER FLOW OVER THE NORTHEAST AND DEVELOPING LOW LEVEL
UPGLIDE AND WARM ADVECTION THIS EVENING. IT MIGHT TAKE A WHILE FOR
ANY SORT OF DIABATIC EFFECTS TO KICK IN. THE MODEL GUIDANCE HAS NOT
BEEN VERIFYING PARTICULARLY WELL WITH DEVELOPING PRECIP INTO THE
FOOTHILLS AND PIEDMONT THIS AFTERNOON AND THINK THAT IT WILL NOT BE
UNTIL BETTER UPGLIDE/UPSLOPE DEVELOPS LATER THIS EVENING BEFORE WE
WILL GET ANY APPRECIABLE PRECIP RESPONSE...SO THE ONSET OF THE
CHANCE POP WAS DELAYED. IT SHOULD EVENTUALLY CATCH UP BEFORE
SUNRISE...BUT DID NOT GO INTO THE LIKELY CATEGORY FOR NOW BECAUSE
THE BETTER FORCING REMAINS TO OUR NORTH. TEMPS WILL COOL OFF SLOWLY
WITH THE INCREASE IN CLOUDS. THE LATEST GUIDANCE KEEPS THE ENTIRE
AREA ABOVE FREEZING...MITIGATING ANY POTENTIAL PROBLEMS NEAR THE
BLUE RIDGE.
ON MONDAY...WE SHOULD HAVE A WELL DEVELOPED COOL POOL ENTRENCHED
ACROSS THE REGION E OF THE BLUE RIDGE THAT SHOULD HOLD ON THROUGH
THE BETTER PART OF THE REGION THROUGH THE DAY GIVEN THE WARM
ADVECTION SEEN AT 850MB OVER THE TOP OF IT. THINK THE NAM HAS THE
BETTER DEPICTION OF ONLY THE SRN/SW FRINGE MANAGING TO MAKE IT INTO
THE WARMER AIR. FORCING WILL INCREASE TO THE WEST AND SOUTH DURING
THE AFTERNOON. PREFRONTAL SHOWERS AND STORMS MAY REACH THE WRN SIDE
OF THE NC MTNS BY THE END OF THE PERIOD SO PRECIP CHANCES GRADUALLY
RISE TO CATEGORICAL BY THE END OF THE DAY. TO THE SOUTH...THE MODELS
SHOW EXCELLENT LOW LEVEL FORCING ALONG THE WEDGE BOUNDARY ACROSS NE
GEORGIA AND THE LAKELANDS...SO PRECIP CHANCES ALSO RAMP UP THERE.
TEMPS FAVOR THE COOLER MET GUIDANCE.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 200 PM SUNDAY...THE DETAILS OF THE EVOLVING PRECIPITATION
EVENT MONDAY NIGHT AND EARLY TUESDAY REMAIN A BIT SKETCHY. THE NAM
ACTUALLY DEPICTS TWO WAVES OF PRECIPITATION MOVING ACROSS THE AREA
DURING THIS PERIOD...THE FIRST BEING THE WARM CONVEYOR BELT/PRE-
FRONTAL WAVE...THE SECOND BEING ALONG AND IMMEDIATELY BEHIND THE
FRONT EARLY TUESDAY...AS A STRONG UPPER JET AXIS/ASSOCIATED VORT MAX
LIFTS INTO THE TENN/OHIO VALLEY. IT IS INTERESTING THAT SOME OF THE
HIGH RES MODELS DEPICT SIMILAR EVOLUTION. I THINK IT/S POSSIBLE IF
NOT LIKELY THAT A NARROW BAND OF SHOWERS WILL DEVELOP ALONG THE
FRONT ACROSS THE TENN VALLEY MONDAY EVENING...BUT WITH STRONGLY
VEERING PRE-FRONTAL FLOW...I CAN/T SEE THIS MAKING A LOT OF HEADWAY
EAST OF THE MTNS. THEREFORE...WE WILL CONTINUE TO DEPICT THE HIGHEST
POPS DURING THE EVENING...BUT WILL HOLD ON TO HIGH CHANCE/LOW LIKELY
POPS ACROSS THE WESTERN MTNS AFTER MIDNIGHT. THERE WILL BE A WANING
MARGINAL SEVERE WEATHER THREAT MONDAY EVENING...MAINLY ACROSS THE
FAR WESTERN MTNS WITH ANY WEAKENING CONVECTIVE FRONTAL BAND...AND
PERHAPS OVER THE FAR SOUTHERN ZONES...WHERE A COUPLE OF DISCRETE
CELLS CANNOT BE RULED OUT IN THE VICINITY OF THE LINGERING CAD
BOUNDARY.
CONDITIONS SHOULD IMPROVE RAPIDLY DURING THE DAY TUESDAY...WITH A
WARM AND SUNNY BUT BREEZY AFTERNOON EXPECTED. LOWERING THICKNESS
VALUES IN RESPONSE TO DEVELOPING EASTERN CONUS LONG WAVE TROUGH WILL
RESULT IN COOLER WEATHER FOR WEDNESDAY...WITH MAXES EXPECTED TO
AVERAGE A CATEGORY OR TWO BELOW CLIMO. WEDNESDAY WILL ALSO BE
ANOTHER VERY BREEZY DAY...IN RESPONSE TO AN APPROACHING CLIPPER.
GUSTS AS HIGH AS 40 MPH WILL BE POSSIBLE IN MOST AREAS DURING THE
AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 230 PM SUNDAY...CONFIDENCE IN THE MEDIUM RANGE IS MUCH LOWER
THAN NORMAL...AS A RATHER COMPLEX LARGE SCALE PATTERN TAKE SHAPE.
THE MOST PROMINENT FEATURE WILL BE THE VERY STRONG POLAR VORTEX THAT
BECOMES ESTABLISHED ACROSS THE NORTHEAST CONUS BY DAY FOUR. THIS
DOES PROVIDE REASONABLE CONFIDENCE THAT TEMPERATURES OVER OUR AREA
WILL BE BELOW NORMAL...IN FACT WELL BELOW NORMAL THROUGH THE LATTER
PART OF THE WEEK. HOWEVER...THE MAJOR GLOBAL MODELS DISAGREE WIDELY
IN THEIR HANDLING OF INDIVIDUAL SHORT WAVE TROUGHS MOVING OUT OF THE
PACIFIC NORTHWEST DURING THE LATTER HALF OF THE PERIOD. IN FACT...BY
DAY SIX...THE NAM AND ECMWF ARE QUITE OUT OF PHASE...WITH A
REINFORCEMENT OF AN EASTERN TROUGH DEPICTED IN THE GFS...AND A
CENTRAL/SOUTHERN ROCKIES TROUGH ADVERTISED IN THE ECMWF. THESE
FACTORS CREATE QUITE THE CONUNDRUM IN TERMS OF THE PRECIP FORECAST
DURING THE LATTER HALF OF THE MEDIUM RANGE. AS SUCH...WE DO NOT FEEL
COMFORTABLE WITH ADVERTISING POPS ANY HIGHER THAN 30 PERCENT DURING
THE PERIOD...NOR DO WE FEEL COMFORTABLE WITH ANYTHING LESS THAN 20
PERCENT. SLIGHT/LOW CHANCE POPS WILL BE ADVERTISED DURING EVERY
PERIOD FROM THURSDAY NIGHT ON. DESPITE THE UNSEASONABLY COOL AIR...
TEMPS ARE EXPECTED TO BE MORE WARM ENOUGH TO SUPPORT MOSTLY RAIN IN
THE PIEDMONT...BUT PERIODS OF SNOW WILL BE POSSIBLE OVER PORTIONS OF
THE MTNS.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
21Z KCLT UPDATE...FRONT HAS SLOWLY MOVED SOUTH OF THE AIRFIELD AT A
STEADY RATE AND I HAVE FAIRLY HIGH CONFIDENCE WINDS WILL REMAIN NE
TO ENE...THAT IS...THE FRONT WILL NOT PUSH BACK NORTH. COLD AIR
OUTRAN THE CLOUDS AND SO THERE IS AN AREA FREE OF LOW CLOUD BETWEEN
THE WSHFT LINE AND THE MORE WEDGELIKE MVFR DECK OVER NRN NC. THIS
AND LLVL COLD ADVECTION ALLOWED FOR MIXING WHICH CAUSED WINDS TO
GUST. NOW THAT CIRRUS ARE FILLING IN OVERHEAD GUSTING MAY DIMINISH.
RAP GUIDANCE BRINGS MVFR IN BY 01Z BUT THIS MAY BE OVERDONE. KEPT
SCT MVFR LEVEL CLOUDS IN FCST AT 00Z...BUT LOWERED THEM TO 020 IN
LIGHT OF RAP AND UPSTREAM OBS.
AT KCLT...WITH SUNSET...THERE SHOULD BE NOTHING TO STOP THE SHALLOW
COOLER AIR FROM MOVING DOWN FROM THE NE. ONCE THE NE FLOW IS
ESTABLISHED...THE WEAK LIFT OVER TOP OF IT DUE TO SW WIND ALOFT WILL
BRING THE LOW CLOUDS OVER THE SRN PIEDMONT...SO CEILING WILL START
TO DROP. MVFR SHOULD HAPPEN IN THE MID TO LATE EVENING AND IFR
DEVELOPING IN THE 07Z TO 09Z TIME FRAME LOOKS LIKE A GOOD BET. VSBY
DOES NOT LOOK LIKE IT WILL DROP MUCH... SO CEILING WAS KEPT ABOVE
006. THE CEILING SHOULD START TO LIFT AROUND 16Z ON MONDAY AS TEMPS
STRUGGLE TO WARM UP.
ELSEWHERE...KHKY HAS SAME CONCERNS AS KCLT...PERHAPS A FEW HOURS
EARLIER. THE SC SITES WILL BE LAST TO SEE A WIND SHIFT OUT OF THE NE
AND DEVELOPING STRATUS...PROBABLY NOT UNTIL A FEW HOURS AFTER
SUNSET. GUIDANCE STILL DOES NOT DEVELOP MUCH PRECIP ALONG THE
FRONT...SO IT WAS LEFT OUT OF THE TAFS. OTHERWISE...LOOKS LIKE
IFR/LOW MVFR CONDITIONS MAINLY DUE TO CEILING WITH A NE WIND UNDER A
COLD AIR DAMMING REGIME THROUGH THE END OF THE TAF PERIOD.
OUTLOOK...COLD AIR DAMMING WEDGE WILL PERSIST ON MONDAY AFTERNOON...
PRODUCING RESTRICTIONS IN CIGS AND -RA. ANOTHER COLD FRONT WILL
CROSS THE AREA FROM THE WEST MONDAY NIGHT/EARLY TUESDAY...
INTRODUCING DRIER AIR AND IMPROVING CONDITIONS FOR TUESDAY. VFR FROM
TUESDAY AFTERNOON ONWARD.
CONFIDENCE TABLE...
20-02Z 02-08Z 08-14Z 14-20Z
KCLT HIGH 94% HIGH 90% MED 79% HIGH 85%
KGSP HIGH 100% HIGH 96% MED 78% HIGH 94%
KAVL HIGH 100% MED 79% MED 76% MED 75%
KHKY HIGH 88% HIGH 96% MED 79% HIGH 92%
KGMU HIGH 100% HIGH 96% MED 78% HIGH 89%
KAND HIGH 100% HIGH 98% HIGH 85% 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...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...PM/WIMBERLEY
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...PM/WIMBERLEY
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
354 PM CDT SUN MAR 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
STRONG FORCING PUSHING OUT INTO THE SOUTHWESTERN PORTIONS OF THE
RUSHMORE STATE AND NEBRASKA PANHANDLE. VERY STEEP LAPSE RATES IN
PLACE EVIDENCED BY A FEW LIGHTNING STRIKES ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA DURING THE EARLY AND MID AFTERNOON. AHEAD OF THIS
WAVE AND DEVELOPING LOW PRESSURE...STRONG SOUTHERLY WINDS IN
PLACE...WITH ADVISORY LEVEL WINDS AT TIMES AROUND THE LOWER BRULE
AREA. THESE WINDS SHOULD EASE A BIT GOING INTO THE EARLY EVENING...
WHILE THE MAIN GRADIENT LIFTS NORTH AND EAST WITH THE MAIN CYCLONE
CENTER HEADING TOWARD EXTREME NORTHEAST SOUTH DAKOTA BY LATE EVENING.
SEVERAL BANDS OF SHOWERS IN PROCESS OF DEVELOPING ACROSS THE STATE.
HI RES MODELS...INCLUDING RAP AND SREF...HAVE TRENDED QUICKER WITH
THE PRECIP...WITH MUCH OF THE BAND EAST OF I29 BY 07-08Z...WITH
EXCEPTION OF AREA ACROSS NORTHERN CWA CLOSER TO THE MID LEVEL
CIRCULATION. NATURE OF A VERY TRANSIENT BAND WILL BE LIMITING FACTOR
ON AMOUNTS...AS WILL THE TEMPERATURES ALOFT WHICH FIGURE UP JUST A
BIT TOO WARM FOR ANY SNOW IN THE FAR SOUTHWEST...AND WILL KEEP A MIX
IN THE WORKS FROM JAMES THROUGH LOWER MISSOURI VALLEY. ONLY THE
COOLER AND SLIGHTLY DRIER AIRMASS TO THE EAST...ALONG WITH THE
DYNAMIC COOLING RESULTING FROM CONVECTIVE NATURE TO PRECIPTIATION
AND SHARP LIFT FORCING WILL FORCE PRECIPITATION OVER TO SNOWFALL.
AMOUNTS SOMEWHAT DIFFICULT TO PIN DOWN GIVEN THE CONVECTIVE
NATURE...WITH AMOUNTS EXPECTED TO REFLECT THE AREAL AVERAGE...
GREATEST ACROSS PARTS OF NORTHWEST IOWA INTO SOUTHWEST MINNESOTA.
DEBATE FOR THE DAY WAS WHAT IT MIGHT TAKE TO GET BLIZZARD CONDTIONS
GIVEN THE CERTAINTY OF STRONG WINDS ON LATE SUNDAY NIGHT AND THROUGH
THE DAY MONDAY. CERTAINLY NONE OF THE REMAINING SNOWCOVER WILL
CONTRIBUTE DIRECTLY...AND REALLY ONLY HAVE AROUND A TWO INCH BAND
ACROSS THE NORTHERN TIER ALONG HIGHWAY 14. STRONGEST WINDS WITH
GUSTS UPWARD OF 45 MPH AT TIMES WILL BE FROM EAST CENTRAL SOUTH
DAKOTA THROUGH SOUTHWEST MINNESOTA...SPEEDS TAPERING OFF SLIGHTLY TO
THE SOUTHWEST...BUT BALANCED SOMEWHAT BY A DEEPER MIXING PROFILE.
NOT EXPECTING A GREAT DEAL OF ADDITIONAL SNOW BY MONDAY...WITH ONLY
THE STEEP LOW LEVEL LAPSE RATES IN REACH OF FAVORABLE ICE GROWTH
RANGE SUGGESTING BANDED SHALLOW SNOW SQUALLS... SO CONTRIBUTIONS
HERE WILL BE FAIRLY MINIMAL. WHERE WE GET A COUPLE OF INCHES OVER
EXISTING SNOW/ICE COVER...WILL BE VERY CAPABLE OF SOME DECENT
LOFTING. WHERE NO SNOWCOVER CURRENTLY EXISTS...WILL BE MUCH MORE
DIFFICULT TO OBTAIN ANY TRUE BLIZZARD CONDITIONS...BUT DID ADD IN A
COUPLE MORE COUNTIES TOWARD THE SOUTH IN SOUTHWEST MINNESOTA TOWARD
WHERE SOME HEAVIER SNOWFALL MAY OCCUR. FARTHER SOUTH AND WEST...
NOT EXPECTING ANY WHITEOUT CONDITIONS TO BE WIDESPREAD...BUT THAT IS
NOT SAYING THERE WOULD BE ANY WHITEOUT CONDITIONS...JUST NOT
WIDESPREAD OR LONG LASTING. CAUTION IS NEEDED...EVEN THROUGH THE
ADVISORY AREA. DID NOT POST BLIZZARD WARNING RIGHT OFF TO START...
AS STRONGER WINDS WILL COME IN LATER TONIGHT/EARLY MONDAY IN THE
WARNING AREA...SO PRECEDED WITH A WINTER WEATHER ADVISORY UP TO 09Z
IN THE BLIZZARD AREA FOR THE COMBINATION OF SNOWFALL AND SOME LESSER
POTENTIAL BLOWING SNOW WITH THE PREFRONTAL SOUTH/SOUTHWEST WINDS.
PROBABLY NOT A GREAT DEAL OF ROOM FOR RECOVERY IN TEMPS ON MONDAY
WITH STRONG SURGE OF COLDER AIR WRAPPING IN BEHIND SYSTEM. ONLY THE
MORE MIXED MISSOURI VALLEY WHERE LESS SNOW IS EXPECTED SHOULD SEE
ANY LESS THAN MINIMAL RECOVERY IN TEMPS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
THE SYSTEM PULLS OUT OF THE REGION ON MONDAY NIGHT...WITH GUSTY
NORTHWESTERLY WINDS DYING THROUGH THE EVENING AS A SURFACE RIDGE
SLIDES SOUTHWARD INTO THE NORTHERN PLAINS CAUSING THE GRADIENT TO
SLACKEN. TEMPERATURES ARE TRICKY THAT NIGHT...DEPENDENT ON HOW
QUICKLY THE WINDS DIE/WHERE NEW FALLEN SNOW IS IN PLACE/AND HOW MUCH
CLEARING IS REALIZED OVERNIGHT. MODEL RH TIME SECTIONS POINT TOWARD
LOWER CLOUDS CLEARING FROM WEST TO EAST DURING THE EVENING...THOUGH
MID/HIGH CLOUDS INCREASING IN THE WEST LATER AT NIGHT. AT THIS
POINT...WENT WITH LOWS AROUND ZERO ALONG HIGHWAY 14 TO THE LOWER
TEENS THROUGH THE MISSOURI RIVER CORRIDOR.
ANOTHER WEAK SHORTWAVE WILL TRACK ACROSS THE AREA ON TUESDAY...AND
MAY BE JUST ENOUGH MOISTURE AROUND TO KICK OFF A FEW FLURRIES IN OUR
EAST. TEMPERATURES WILL STILL BE MUCH BELOW NORMAL FOR THIS TIME OF
YEAR WITH HIGHS GENERALLY IN THE 20S NORTH TO 30S SOUTH. FARTHER
INTO THE EXTENDED...A BROAD UPPER LEVEL LOW OVER THE EASTERN
PORTIONS OF THE COUNTRY WILL KEEP OUR AREA IN A NORTHWESTERLY UPPER
LEVEL FLOW FOR WEDNESDAY AND EARLY THURSDAY BEFORE THE NEXT
SHORTWAVE BEGINS TO ENCROACH ON THE AREA IN THE LATE THURSDAY TO
FRIDAY TIME FRAME. MODELS CONTINUE TO DIFFER ON HOW THEY HANDLE THIS
SYSTEM...WITH BOTH THE ECMWF AND GEM KEEPING IT FARTHER TO THE
SOUTH..AND THE GFS PERSISTING WITH A MORE NORTHERLY SOLUTION. SOME
CONSENSUS...WEIGHED MORE HEAVILY TO THE MORE SOUTHERLY SOLUTION
WOULD BRING A CHANCE OF LIGHT SNOW TO OUR SOUTHWEST DURING THIS TIME
FRAME. MODELS KEEP MUCH BELOW NORMAL THERMAL PROFILES IN PLACE
ACROSS THE REGION THROUGH NEXT WEEKEND...WITH HIGHS GENERALLY 20S AND
30S...AND LOWS SINGLE DIGITS AND TEENS EARLY ON...TO TEENS AND 20S
LATE IN THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1249 PM CDT SUN MAR 17 2013
MANY COMPLEX AVIATION ISSUES FOR THIS TAF ISSUANCE SET. STRONG
WAVE SET TO PUSH OUT OF WYOMING INTO WESTERN SD AND THE NEBRASKA
PANHANDLE AT MIDDAY. FAIRLY SCATTERED PRECIPITATION STARTING TO
DEVELOP IN THE WEST THIS AFTERNOON...EXPECTED TO BECOME MORE
WIDESPREAD WITH INCREASED FORCING. MUCH OF INITIAL PRECIP TO THE
WEST SHOULD FAVOR A LIQUID FORM...BUT AS INTENSITY INCREASES AND
MOVEMENT OF LIFT FORCING SHIFTS TOWARD INTO THE COOLER AND DRIER
AIRMASS TO THE EAST...SHOULD GET A FAIRLY RAPID TRANSITION OVER
TOWARD SNOW...OCCURING BY EARLY EVENING AT KHON...MID EVENING FOR
KFSD...AND LATER FOR KFSD. VERY CONVECTIVE COMPONENT TO DEVELOPING
PRECIP...SO MAY BE HEAVY WITH VISIBILITIES LIKELY EVEN LOWER FOR
SHORT PERIODS OF TIME WITHIN CORE OF SNOW BAND...PERHAPS BRIEFLY
INTO VLIFR.
WINDS OF SECONDARY CONCERN. STRONG SOUTHEAST WINDS WITH GUSTS AT
OR ABOVE 35 KNOTS WEST OF THE JAMES VALLEY TODAY. COULD BE A
PERIOD OF MARGINAL LOW LEVEL WIND SHEAR THIS EVENING WITH PARTIAL
DECOUPLING...BUT STRONGEST WINDS ARE LIKELY TO OCCUR LATER TONIGHT
THROUGH MONDAY BEHIND THE COLD FRONT AND EXITING AREA OF LOW
PRESSURE. MOST LIKELY AREA TO EXPERIENCE ANY SEVERELY REDUCED
VISIBILITY WITH BLOWING SNOW/SNOW SQUALLS WOULD BE NORTH AND EAST
OF THE KFSD TAF SITE...MAINLY KBKX/KMML/KMWM CORRIDOR. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
MONDAY FOR SDZ038-054>056-062-067.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ050-052-053-
057>061-063>066-068>071.
WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR SDZ050-052-057-058-
063-064.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT
MONDAY FOR SDZ039-040.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ039-040.
MN...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
MONDAY FOR MNZ089-090-097-098.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT
MONDAY FOR MNZ071-072-080-081.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR MNZ071-072-080-
081.
IA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
MONDAY FOR IAZ001>003-012>014-020>022-032.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR IAZ031.
NE...WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR NEZ013-014.
&&
$$
SHORT TERM...CHAPMAN
LONG TERM...JM
AVIATION...CHAPMAN
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1123 PM MDT SAT MAR 16 2013
.UPDATE...
ISSUED AT 600 PM MDT SAT MAR 16 2013
VIGOROUS LIFT ASSOCIATED WITH A ZIPPERING TROUGH ALONG A QUASI-
STATIONARY FGEN ZONE...HAS BEEN SUPPORTING HEAVY SNOWFALL ALONG
NARROW BAND OVER WEST CENTRAL SD. LATEST GUIDANCE SUGGEST
CONCENTRATED LIFT WILL CONTINUE ACROSS MAINLY
PENNINGTON/JACKSON/AND INTO MELLETTE COUNTIES THROUGH MUCH OF THIS
EVENING...WITH VERY EFFICIENT SNOW PRODUCTION GIVEN LIFT FOCUSED
IN THE DGZ. LOSS OF INSOLATION WITH FALLING TEMPS HAS SUPPORTED
ACCUMS ON ROADWAYS WITH BLACK ICE LIKELY GIVEN EARLIER SNOW MELT.
LATEST QPF GUIDANCE AND CURRENT RADAR/SAT ANALYSIS SUGGEST THAT
2-5 INCHES OF ADDITIONAL ACCUMS WILL POSSIBLE THROUGH THIS
EVENING...ESP WHERE BANDING PERSISTS. IN ADDITION...SATELLITE
ANALYSIS COUPLED WITH THE 00Z RAP RAOB INDICATED A POTENTIALLY
UNSTABLE ENVIRONMENT WITH LIKELY CONVECTIVE ENHANCEMENT OWING TO
1-2 INCHES AN HOUR SNOWFALL RATES INSIDE THE BAND. HAVE ISSUED A
WINTER WEATHER ADV.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 226 PM MDT SAT MAR 16 2013
UPPER LEVEL ANALYSIS HAS ZONAL FLOW OVER THE NORTHERN PLAINS WITH
WEAK SHORTWAVE CROSSING SOUTHEASTERN MONTANA AND NORTHEASTERN
WYOMING AT THE MOMENT. REGIONAL RADARS SHOWING A LIGHT TO MODERATE
BAND OF SNOW FROM THE CENTRAL AND SOUTHERN BLACK HILLS EXTENDING
EAST ONTO THE PLAINS. SEVERAL INCHES OF SNOW HAS FALLEN IN AREAS
WHERE THE HEAVIEST BANDS HAVE SET UP. AT THE SURFACE...ARCTIC HIGH
HAS SETTLED INTO NORTH DAKOTA WITH COOLER AIR BACKING INTO WESTERN
SOUTH DAKOTA. BROAD AREA OF STRATUS IN PLACE ACROSS SOUTHWESTERN
SOUTH DAKOTA AS WARMER/MOISTER AIR OVERRUNS THE COOLER AIR AT THE
SURFACE.
LATE THIS AFTERNOON AND TONIGHT...BAND OF SNOW EXTENDING FROM THE
BLACK HILLS EASTWARD WILL CONTINUE TO PRODUCE LIGHT TO MODERATE
SNOW FOR THE REMAINDER OF THE AFTERNOON AND EARLY EVENING. ONE TO
TWO ADDITIONAL INCHES OF SNOW WILL BE POSSIBLE...WITH SOME LOCALLY
HIGHER AMOUNTS. LIGHT SNOW WILL FINALLY SHIFT EAST LATER TONIGHT
AS MAIN SHORTWAVE MOVES OUT AND WEAK TRANSIENT RIDGE BUILDS IN.
FOR SUNDAY...STRONG/FAST MOVING SHORTWAVE TROUGH WILL MOVE FROM
WESTERN MT/ID TO MN BY 12Z MONDAY. SURFACE LOW WILL DEVELOP ALONG
THE MT/WY BORDER...MOVING INTO WESTERN SD BY 00Z...AND THEN
NORTHEAST MN BY 12Z MONDAY. IT WILL DRAG A STRONG COLD FRONT
THROUGH THE CWA SUNDAY AFTERNOON/EVENING. AHEAD OF THE FRONT 30KT+
SOUTHERLY JET DEVELOPS WHICH WILL PARTIALLY MIX TO THE GROUND BY
MIDDAY RESULTING IN WINDY SPOTS ACROSS SOUTH CENTRAL SOUTH DAKOTA.
40KT+ 850MB WEST TO NORTHWEST WINDS DEVELOP BEHIND THE COLD FRONT
AS IT SHIFTS EAST. CURRENT HIGH WIND WATCH FOR MUCH OF WESTERN
SOUTH DAKOTA LOOKS GOOD. OTHER IMPACT OF COLD FRONT AND STRONG
WINDS WILL BE LOWER VISIBILITIES WITH SNOW SHOWERS AFTER FRONTAL
PASSAGE. WINDS LOOK TO REMAIN FAIRLY STRONG INTO SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 226 PM MDT SAT MAR 16 2013
DEEP NORTHWESTERLY FLOW ALOFT IS EXPECTED ACROSS THE REGION FOR THE
FIRST HALF OF THE WORK WEEK. WEAK DISTURBANCES IN THE FLOW WILL
BRING AT LEAST SLIGHT CHANCES FOR SNOW SHOWERS ACROSS FAR
NORTHEASTERN WY...THE BLACK HILLS...AND PORTIONS OF NORTHWESTERN SD
MONDAY THROUGH TUESDAY. OTHERWISE...MAINLY DRY WEATHER IS EXPECTED
THROUGH WEDNESDAY. TEMPERATURES WILL BE A BIT TRICKY EARLY IN THE
WEEK WITH FRONTAL BOUNDARY IN PLACE OVER THE AREA. AM GENERALLY
EXPECTING A WARMING TREND ACROSS WESTERN AREAS THROUGH MIDWEEK...
WITH BELOW AVERAGE TEMPERATURES TO THE EAST OF THE BLACK HILLS. THE
NEXT SERIES OF WEATHER SYSTEMS WILL MOVE INTO THE REGION LATER
WEDNESDAY NIGHT AND THURSDAY. THE STRONGEST OF THESE DISTURBANCES
LOOKS LIKE IT WILL MOVE THROUGH THURSDAY INTO THURSDAY NIGHT. WILL
KEEP POP CHANCES ON THE HIGH SIDE FOR THESE PERIODS. LONG RANGE
MODELS ARE HAVING A HARD TIME HANDLING THE PATTERN BEYOND
FRIDAY...BUT THEY ARE LEANING TOWARD DRIER NORTHWESTERLY FLOW INTO
NEXT WEEKEND...SO WILL GO WITH DRY FORECAST FOR SATURDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1102 PM MDT SAT MAR 16 2013
IFR TO LIFR CIGS AND VIS WILL CONTINUE ACROSS MOST OF THE FA INTO
SAT MORNING. SOUTHERLY WINDS WILL INCREASE AND MAY ALLOW THE
LIFTING OF SOME OF THE FOG TO STRATUS. AREAS OF FREEZING DRIZZLE
WILL BE POSSIBLE THROUGH MORNING...ESP IN AND AROUND THE BLACK
HILLS. SOUTHERLY WINDS WILL INCREASE THROUGH MORNING...BEING ESP
GUSTY OVER NE WY. STRONG LOW PRESSURE WILL DEVELOP AND PUSH EAST
THROUGH THE REGION SUNDAY...WITH VERY STRONG WESTERLY WINDS
DEVELOPING BEHIND THE SFC TROUGH/COLD FRONT. SUSTAINED WINDS OF 25
TO 40 MPH WITH GUSTS OVER 60 WILL BE POSSIBLE...ESP OVER THE
NORTHERN AND EASTERN FOOTHILLS OF THE BLACK HILLS. ANOTHER PERIOD
OF MVFR CIGS WILL BE POSSIBLE ACROSS THE NORTHERN FA...IN RAIN AND
SNOW BEHIND THE SFC COLD FRONT SUNDAY AFTERNOON AND EVENING.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
FOR SDZ001-002-012-013-025-026-030-031-041>044-072>074.
WY...NONE.
&&
$$
UPDATE...JC
SHORT TERM...15
LONG TERM...26
AVIATION...JC
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1129 PM CDT SAT MAR 16 2013
.UPDATE...
FORECAST HAS BEEN UPDATED MAINLY FOR OVERNIGHT WINDS AND LOW
TEMPERATURES...SEE DISCUSSION.
&&
.DISCUSSION...
THE COLD FRONT HAS MADE MORE SOUTHWARD PROGRESS DURING THE EVENING THAN
THE MODELS HAD INDICATED...AND HAS ENTERED THE NORTHERN CONCHO VALLEY.
RADAR LOOP INDICATES THAT THE FRONT IS CURRRENTLY SLOWING
DOWN...HOWEVER. THE LATEST RUC13 LOOKS TO HAVE THE BEST HANDLE ON THIS
FRONT...BRINGING IT SOUTH TO SAN ANGELO SHORTLY BEFORE 11Z. THE FRONT
SHOULD BE APPROACHING THE INTERSTATE 10 CORRIDOR AROUND MIDDAY SUNDAY.
BASED ON THESE CONSIDERATIONS...HAVE MADE SLIGHT DOWNWARD ADJUSTMENTS
TO OVERNIGHT LOWS ACROSS THE NORTHERN BIG COUNTRY...AND HAVE ADJUSTED
LOWS UP ACROSS OUR SOUTHERN COUNTIES. HAVE ALSO MADE ADJUSTMENTS TO
THE WIND...TEMPERATURE AND DEWPOINTS GRIDS TO MATCH WHAT HAS OCCURRED
DURING THE PAST FEW HOURS. UPDATED FORECAST PRODUCTS HAVE BEEN SENT.
&&
.PREV DISCUSSION... /ISSUED 544 PM CDT SAT MAR 16 2013/
DISCUSSION...
SEE AVIATION DISCUSSION BELOW...
AVIATION...
A COLD FRONT IS CURRENTLY OVER NORTH TEXAS AND WILL APPROACH KABI
AROUND 09Z...KSJT AROUND 12Z....AND THE SOUTHERN SITES BETWEEN 15
AND 16Z. WINDS WILL BECOME NORTH TO NORTHWEST AT 8 TO 12 KNOTS
BEHIND THE BOUNDARY...WITH SOME POST FRONTAL STRATUS REDUCING
CEILINGS TO AROUND 3K FEET...MAINLY AT KABI. IN
ADDITION...STRATUS DEVELOPMENT IS EXPECTED AROUND 12Z AT
KJCT...AHEAD OF THE FRONT...RESULTING IN MVFR CEILINGS. FOR NOW I
HAVE LEFT KBBD AND KSOA VFR...BUT I WILL CONTINUE TO MONITOR. VFR
CONDITIONS WILL RETURN TO ALL TAF SITES BY MID TO LATE MORNING
SUNDAY.
PREV DISCUSSION... /ISSUED 342 PM CDT SAT MAR 16 2013/
SHORT TERM...
A WEAK COLD FRONT WILL PUSH INTO THE BIG COUNTRY THIS EVENING AND
INTO THE CONCHO VALLEY TOWARD MORNING. THE SLIGHTLY FASTER NAM AND
RAP MODELS APPEAR TO PLACE THE FRONT BETTER THIS AFTERNOON. THE
FRONT MOVES ALONG THE I-20 CORRIDOR TOWARDS MIDNIGHT...AND THE
CONCHO VALLEY EARLY SUNDAY MORNING. WENT CLOSE TO GFS/NAM MOS FOR
HIGHS IN THE BIG COUNTRY SUNDAY...AS BOTH NAM AND GFS MODELS
INDICATE SOME POST FRONTAL STRATUS IN THE MORNING. GOING WARMER
HOWEVER SOUTH OF THE BIG COUNTRY...AS WINDS SHIFT WESTERLY IN THE
AFTERNOON...BRINGING A DOWNSLOPE COMPONENT ALONG WITH NEARLY FULL
SUN.
04
LONG TERM...
A VERY PROGRESSIVE MID/UPPER LEVEL PATTERN WILL UNLEASH A PARADE
OF SHORTWAVE TROUGHS ACROSS THE CENTRAL CONUS THROUGH THE
WEEKEND. WE WILL SEE ONE OF THESE SYSTEMS MOVE ACROSS THE SOUTHERN
PLAINS LATE SUNDAY NIGHT. THIS WILL REINFORCE TOMORROW/S COLD
FRONT WITH ANOTHER GLANCING BLOW OF COOLER AIR FOR MONDAY. TEMPS
ARE STILL EXPECTED TO REMAIN ABOVE NORMAL BUT MOST AREAS SHOULD BE
IN THE 70S FOR AFTERNOON HIGHS. NORTH TO NORTHWEST WINDS MAY BE
GUSTY EARLY BUT ARE FORECAST TO SUBSIDE AFTER 18Z AS THE SURFACE
HIGH BUILDS INTO THE REGION.
MODEL DIFFERENCES ARE ALREADY BECOMING AN ISSUE BY TUESDAY. WE
WILL SEE SOUTHERLY FLOW RETURN MONDAY NIGHT BUT ANOTHER
SHORTWAVE TROUGH WILL MOVE OUT OF THE FOUR CORNERS AND BRING
ANOTHER WEAK COLD FRONT INTO WEST CENTRAL TX. THE GFS IS THE ONLY
MODEL THAT TRIES TO DEVELOP ANY PRECIPITATION /TUESDAY EVENING/
DESPITE IT HAVING NO APPRECIABLE MOISTURE BELOW 10 KFT AGL. WITH
THE REMAINING MODELS SHOW NO SIGN OF THIS SO I HAVE IGNORED THESE
RAIN CHANCES. OTHERWISE...EXPECT HIGHS MAINLY IN THE MID/UPPER
70S. THE AFOREMENTIONED COLD FRONT WILL BRING COOLER TEMPS TO THE
AREA ON WEDNESDAY. I HAVE LOWERED MAX TEMPS INTO THE UPPER 60S TO
LOWER 70S AREAWIDE. EASTERLY WINDS...WEAK COLD ADVECTION AND
ABUNDANT MID/HIGH LEVEL CLOUD COVER SHOULD TEMPER WARMING.
ISENTROPIC ASCENT COULD BE STRONG ENOUGH TO PROVIDE SOME VERY
LIGHT SHOWERS BUT I WOULD LIKE TO SEE MORE CONTINUITY BEFORE
INTRODUCING THIS TO THE FORECAST.
SOUTH WINDS ARE EXPECTED TO RETURN BRIEFLY WEDNESDAY NIGHT WITH A
STRONG LOW LEVEL JET RESULTING IN RAPID POLEWARD MOISTURE
ADVECTION. I THINK DEWPOINTS WILL LIKELY REBOUND INTO THE LOWER
50S BY THURSDAY MORNING AND MAY INCREASE FURTHER AFTER SUNRISE.
THE QUESTION OF THE DAY IS WHETHER OR NOT THE DRYLINE/PACIFIC
FRONT WILL MOVE EAST OF THE CWA BY THURSDAY AFTERNOON OR WILL IT
FOLLOW THE LATEST MODEL TRENDS AND SLOW ENOUGH TO PROVIDE A FOCUS
FOR CONVECTION DURING THE AFTERNOON HOURS ACROSS THE EASTERN
ZONES. THE CONSENSUS /THROWING OUT THE MUCH MORE AGGRESSIVE DGEX/
WAS THAT WE MAY SEE THE BOUNDARY STALL JUST EAST OF AN ABILENE TO
SAN ANGELO LINE...WITH SUFFICIENT MOISTURE TO SUPPORT CONVECTION
IN THE WARM SECTOR. MODIFIED GFS POINT SOUNDINGS STILL SHOW SOME
SEMBLANCE OF AN ELEVATED MIXED LAYER CAPPING SURFACE BASED
CONVECTION BUT THE ECMWF REMOVES THIS CAP A BIT EARLIER AND SHOWS
LITTLE IN THE WAY OF CINH. I THOUGHT THE POTENTIAL WAS GREAT
ENOUGH TO AT LEAST INCLUDE MENTION IN THE FORECAST. SLIGHT CHANCE
POPS WERE ADDED TO AREAS EAST OF A HASKELL...TO BALLINGER...TO
SONORA LINE.
A STRONGER COLD FRONT IS PROGGED BY THE MEDIUM RANGE MODELS FOR
THURSDAY NIGHT INTO FRIDAY. H85 TEMPS ARE FORECAST TO DROP TO 0
TO -4C ACROSS THE BIG COUNTRY WITH LOW SINGLE DIGITS ACROSS THE
SOUTHERN ZONES. STRONG COLD ADVECTION IS EXPECTED TO RESULT IN
MUCH COOLER TEMPS FRIDAY AND SATURDAY. I HAVE KNOCKED HIGHS BACK
QUITE A BIT...SHOWING MAINLY 60S ON FRIDAY WITH 50S ON SATURDAY. I
ALSO LOWERED MIN TEMPS FRIDAY NIGHT INTO THE 30S IN THE DRY POST
FRONTAL AIR. THE ECMWF SUGGESTS THAT HIGHS WOULD REMAIN IN THE 40S
BUT THE GFS AND ENSEMBLES ARE A BIT WARMER.
JOHNSON
FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS WILL CONTINUE THIS AFTERNOON
AHEAD OF A COLD FRONT IN THE SOUTH PLAINS...SOUTH OF A LUBBOCK
TO CHILDRESS LINE. THE COLD FRONT WILL GRADUALLY MOVE SOUTHWARD
INTO THE BIG COUNTRY THIS EVENING... PUSHING SOUTH THE I-20
CORRIDOR AROUND MIDNIGHT...THEN INTO THE CONCHO VALLEY VALLEY
TOWARDS MORNING. THE COLD FRONT WILL BE SHORT LIVED HOWEVER...
WITH WINDS RETURNING TO THE WEST AND NORTHWEST SUNDAY AFTERNOON.
WINDS SPEEDS ON SUNDAY WILL BE LOWER SUNDAY...KEEPING FIRE WEATHER
CONDITIONS FROM BECOMING CRITICAL.
04
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 48 69 51 72 43 / 0 0 5 0 0
SAN ANGELO 52 82 49 78 44 / 0 0 0 0 0
JUNCTION 57 86 47 84 42 / 0 0 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
556 PM EDT SUN MAR 17 2013
.SYNOPSIS...
COLD AIR DAMMING IS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK NORTH AS A WARM FRONT
LATE IN THE DAY BUT THE WARM AIR WILL LIKELY ONLY WORK ITS WAY
BACK INTO FAR SOUTHWEST VIRGINIA AND PARTS OF THE PIEDMONT BY LATE
MONDAY. WIDESPREAD BUT GENERALLY LIGHT PRECIPITATION... SOME IN
THE FORM OF WINTRY WEATHER ACROSS THE NORTH...WILL OVERSPREAD THE
AREA TONIGHT. THEN WINDY CONDITIONS SPREAD INTO THE REGION BEHIND
THE COLD FRONT BY TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 555 PM EDT SUNDAY...
HAVE ADDED AREAS OF FOG IN THE COLD AIR DAMMING REGION WHERE
VISIBILITIES IN SOME SPOTS WERE BELOW ONE MILE.
AS OF 410 PM EDT SUNDAY...
COLD WEDGE REMAINS IN PLACE ACROSS THE REGION...WITH PATCHES OF
DRIZZLE AND SOME MAINLY LIGHT FOG EXCEPT FOR RIDGES. TEMPERATURES
AND DEW PTS SO FAR REMAIN ABOVE FREEZING AT REPORTING STATIONS IN
THE AREA ALTHOUGH TEMPS HAVE REMAINED STEADY OR SLOWLY FALLING
THIS AFTERNOON WITH MUCH COLDER AIR NOT TOO FAR OFF TO THE NORTH.
MODELS STRUGGLING WITH QPF ALONG 850 FRONT TO OUR NORTHWEST AND
HAVE BEEN TRYING TO PUSH PRECIP IN ACROSS SE WV MOST OF THE DAY.
APPEARS LOOKING AT RADAR AND SOME HELP FROM HRRR THAT THOSE AREAS
WILL HAVE TO WAIT UNTIL AFTER 00Z BEFORE IT BEGINS TO SNEAK INTO
WRN GREENBRIER AGAIN. ALSO MODELS LIKELY OVERDOING SOME UPSLOPE
PRECIP ALONG BLUE RIDGE THIS EVENING...WHICH WILL BE MORE IN THE
FORM OF DRIZZLE...BUT COULD AMOUNT TO A FEW HUNDREDTHS SO WENT
AHEAD AND INCLUDED HIGH CHC TO LIKELY...INCREASING AS THE EVENING
PROGRESSES.
MAIN QSTN OVERNIGHT IS WHICH LOCATIONS WILL SEE FROZEN
PRECIP...AND WITH BIG DIFFERENCES IN TEMP PROFILES ALOFT...THIS IS
TRICKY. NAM STILL HAS STRONG WARM NOSE AND WITH THE COLDEST SFC
TEMPS SUGGEST MANY LOCATIONS FROM NRV NORTHWARD WOULD SEE FREEZING
RAIN. GFS...RAP...AND MANY SREF MEMBERS HAVE WEAK TO NO WARM
NOSE...AND THIS IS THE IDEA WE ARE STILL LEANING WITH IN THE
FORECAST...WHICH WOULD SUGGEST SLEET OR SNOW...THE FARTHER NORTH
UP TOWARD NORTHERN BORDER WITH WFO STERLING...THE MORE SNOW.
PROBLEM IS THE QPF. MOST OF THIS COMES IN BEFORE 06Z...AND MANY
AREAS WOULD STILL BE SEEING RAIN...EXCEPT FOR HIGHEST ELEVATIONS.
ALSO THINK MODELS ARE A BIT OVERDONE ON QPF. WHAT DOES FALL AFTER
MIDNIGHT WOULD BE THE SLEET AND SNOW MIX...BUT PRECIP AMOUNTS WILL
BE FROM A TENTH TO A QUARTER OF AN INCH BY THEN.
BASED ON THIS...LEANED TOWARD LOWER SLEET/SNOW TOTALS THAN
PREVIOUS FORECAST...BUT THIS STILL GIVES 1 TO 3 INCHES ACROSS FAR
NORTH...MAINLY GREENBRIER TO BATH TO ROCKBRIDGE AND INTO HIGHER
ELEVATIONS ALONG BLUE RIDGE. AN INCH OR SO FROM CRAIG TO ROANOKE
TO AMHERST AND PARTS OF GREENBRIER. ONE THING TO CONSIDER IS THE
POSSIBILITY OF SHALLOW MOISTURE UPSLOPING ALONG BLUE
RIDGE...AND/OR THE WARM NOSE AS FCST BY THE NAM BEING A LITTLE
STRONGER...WHICH MIGHT RESULT IN SOME AREAS OF LIGHT FREEZING RAIN
OR FREEZING DRIZZLE. DID NOT INCLUDE THAT SPECIFICALLY IN
FCST... THIS POSSIBILITY IS ONE REASON WHY DECIDED TO LEAVE THE
ADVISORY GOING AS FAR SOUTH AS CRAIG AND BOTETOURT
COUNTIES...SINCE THE SNOW/SLEET ACCUMS WILL BE MINIMAL. ROADS MAY
NOT HAVE MANY PROBLEMS EITHER DUE TO RECENT WARM TEMPS...BUT
BRIDGES AND OVERPASSES...AS WELL AS SIDEWALKS MAY GET A LITTLE
SLICK WITH LIGHT SLEET/SNOW MIX.
WENT WITH COLDER GUIDANCE IN MET FOR LOWS TONIGHT...ACTUALLY 1-2
DEG COLDER IN UPSLOPE AREAS FROM EASTERLY FLOW...AND COLDER THAN
GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN VERY LATE IN THE
DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING IN FAR SW AND
WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT AND PARTS OF
SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY TEMPS MONDAY.
SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE DAY...WHICH
WILL PROVIDE MIXING TO HELP BREAK BREAK THE WEDGE...AND DECIDED
THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS LATE ENOUGH TO NOT
MENTION UNTIL EVENING TIME FRAME. THE TRICKY PART OF MONDAY`S
FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF SHOWERS IN THE
WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH WARMER
TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSOCIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH
THAT IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST
ELEVATIONS WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4
ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGERING LOW LEVEL MOISTURE IN THE MTNS MAY
RESULT IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS
85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
AS OF 115 AM EDT
SUNDAY...
VERY POOR AVIATION CONDITIONS ARE EXPECTED THIS AFTERNOON INTO
TOMORROW MORNING AS A FRONTAL BOUNDARY STALLS TO THE SOUTH OF THE
CWA AND COLD CANADIAN HIGH PRESSURE MOVES TOWARD THE NORTHERN MID-
ATLANTIC. MVFR TO IFR CIGS AND VSBYS WILL ONLY INTENSIFY AS RAIN
SERVES TO INTENSIFY THE WEDGE. AFT 06Z...THERE IS SOME CONCERN
FOR WINTER PCPN AT LWB/BCB/ROA...AND POSSIBLY LYH IN THE FORM OF
SN/PL. DO EXPECT ACCUMULATING SNOW AT LWB...BUT ANY WINTER PCPN
FOR ROA/BCB SHOULD BE CONFINED TO THE 08Z-14Z TIME FRAME AND ONLY
LIMITED ACCUMULATION EXPECTED BEFORE PCPN CHANGES BACK TO -RA.
EXTENDED AVIATION DISCUSSION...
SUNDAY THROUGH WEDNESDAY CAN BEST CHARACTERIZED AS UNSETTLED. THE
FRONTAL BOUNDARY WILL NOT COMPLETELY CLEAR THE AREA UNTIL TUESDAY
MORNING. UNTIL THEN PERIODS OF RAIN AND LOW CEILINGS WILL BRING
EXTENDED PERIODS OF MVFR/IFR CONDITIONS TO ALL TAF LOCATIONS.
CONDITIONS WILL IMPROVE DRAMATICALLY BY TUESDAY AFTERNOON AND LAST
THROUGH WEDNESDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...AMS/SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...JC/RAB
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
423 PM EDT SUN MAR 17 2013
.SYNOPSIS...
COLD AIR DAMMING IS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK NORTH AS A WARM FRONT
LATE IN THE DAY BUT THE WARM AIR WILL LIKELY ONLY WORK ITS WAY
BACK INTO FAR SOUTHWEST VIRGINIA AND PARTS OF THE PIEDMONT BY LATE
MONDAY. WIDESPREAD BUT GENERALLY LIGHT PRECIPITATION... SOME IN
THE FORM OF WINTRY WEATHER ACROSS THE NORTH...WILL OVERSPREAD THE
AREA TONIGHT. THEN WINDY CONDITIONS SPREAD INTO THE REGION BEHIND
THE COLD FRONT BY TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 410 PM EDT SUNDAY...
COLD WEDGE REMAINS IN PLACE ACROSS THE REGION...WITH PATCHES OF
DRIZZLE AND SOME MAINLY LIGHT FOG EXCAPT FOR RIDGES. TEMPERATURES
AND DEW PTS SO FAR REMAIN ABOVE FREEZING AT REPORTING STATIONS IN
THE AREA ALTHOUGH TEMPS HAVE REMAINED STEADY OR SLOWLY FALLING
THIS AFTERNOON WITH MUCH COLDER AIR NOT TOO FAR OFF TO THE NORTH.
MODELS STRUGGLING WITH QPF ALONG 850 FRONT TO OUR NORTHWEST AND
HAVE BEEN TRYING TO PUSH PRECIP IN ACROSS SE WV MOST OF THE DAY.
APPEARS LOOKING AT RADAR AND SOME HELP FROM HRRR THAT THOSE AREAS
WILL HAVE TO WAIT UNTIL AFTER 00Z BEFORE IT BEGINS TO SNEAK INTO
WRN GREENBRIER AGAIN. ALSO MODELS LIKELY OVERDOING SOME UPSLOPE
PRECIP ALONG BLUE RIDGE THIS EVENING...WHICH WILL BE MORE IN THE
FORM OF DRIZZLE...BUT COULD AMOUNT TO A FEW HUNDREDTHS SO WENT
AHEAD AND INCLUDED HIGH CHC TO LIKELY...INCREASING AS THE EVENING
PROGRESSES.
MAIN QSTN OVERNIGHT IS WHICH LOCATIONS WILL SEE FROZEN
PRECIP...AND WITH BIG DIFFERENCES IN TEMP PROFILES ALOFT...THIS IS
TRICKY. NAM STILL HAS STRONG WARM NOSE AND WITH THE COLDEST SFC
TEMPS SUGGEST MANY LOCATIONS FROM NRV NORTHWARD WOULD SEE FREEZING
RAIN. GFS...RAP...AND MANY SREF MEMBERS HAVE WEAK TO NO WARM
NOSE...AND THIS IS THE IDEA WE ARE STILL LEANING WITH IN THE
FORECAST...WHICH WOULD SUGGEST SLEET OR SNOW...THE FARTHER NORTH
UP TOWARD NORTHWERN BORDER WITH WFO STERLING...THE MORE SNOW.
PROBLEM IS THE QPF. MOST OF THIS COMES IN BEFORE 06Z...AND MANY
AREAS WOULD STILL BE SEEING RAIN...EXCEPT FOR HIGHEST ELEVATIONS.
ALSO THINK MODELS ARE A BIT OVERDONE ON QPF. WHAT DOES FALL AFTER
MIDNIGHT WOULD BE THE SLEET AND SNOW MIX...BUT PRECIP AMOUNTS
WILL BE FROM A TENTH TO A QUARTER OF AN INCH BY THEN.
BASED ON THIS...LEANED TOWARD LOWER SLEET/SNOW TOTALS THAN
PREVIOUS FORECAST...BUT THIS STILL GIVES 1 TO 3 INCHES ACROSS FAR
NORTH...MAINLY GREENBRIER TO BATH TO ROCKBRIDGE AND INTO HIGHER
ELEVATIONS ALONG BLUE RIDGE. AN INCH OR SO FROM CRAIG TO ROANOKE
TO AMHERST AND PARTS OF GREENBRIER. ONE THING TO CONSIDER IS THE
POSSIBILITY OF SHALLOW MOISTURE UPSLOPING ALONG BLUE
RIDGE...AND/OR THE WARM NOSE AS FCST BY THE NAM BEING A LITTLE
STRONGER...WHICH MIGHT RESULT IN SOME AREAS OF LIGHT FREEZING RAIN
OR FREEZING DRIZZLE. DID NOT INCLUDE THAT SPECIFICALLY IN
FCST... THIS POSSIBILITY IS ONE REASON WHY DECIDED TO LEAVE THE
ADVISORY GOING AS FAR SOUTH AS CRAIG AND BOTETOURT
COUNTIES...SINCE THE SNOW/SLEET ACCUMS WILL BE MINIMAL. ROADS MAY
NOT HAVE MANY PROBLEMS EITHER DUE TO RECENT WARM TEMPS...BUT
BRIDGES AND OVERPASSES...AS WELL AS SIDEWALKS MAY GET A LITTLE
SLICK WITH LIGHT SLEET/SNOW MIX.
WENT WITH COLDER GUIDANCE IN MET FOR LOWS TONIGHT...ACTUALLY 1-2
DEG COLDER IN UPSLOPE AREAS FROM EASTERLY FLOW...AND COLDER THAN
GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN VERY LATE IN THE
DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING IN FAR SW AND
WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT AND PARTS OF
SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY TEMPS MONDAY.
SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE DAY...WHICH
WILL PROVIDE MIXING TO HELP BREAK BREAK THE WEDGE...AND DECIDED
THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS LATE ENOUGH TO NOT
MENTION UNTIL EVENING TIME FRAME. THE TRICKY PART OF MONDAYS
FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF SHOWERS IN THE
WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH WARMER
TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSICIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH THAT
IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST ELEVATIONS
WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4 ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGING LOW LEVEL MOISTURE IN THE MTNS MAY RESULT
IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURRING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS 85H
TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONCENSUS ON HOW
FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR THE
ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS LUCK
WOULD HAVE IT...WINTER AINT OVER...SO PTYPE CHALLENGE WILL ALSO COME
INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR NORTH.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AS OF 115 AM EDT
SUNDAY...
VERY POOR AVIATION CONDITIONS ARE EXPECTED THIS AFTERNOON INTO
TOMORROW MORNING AS A FRONTAL BOUNDARY STALLS TO THE SOUTH OF THE
CWA AND COLD CANADIAN HIGH PRESSURE MOVES TOWARD THE NORTHERN MID-
ATLANTIC. MVFR TO IFR CIGS AND VSBYS WILL ONLY INTENSIFY AS RAIN
SERVES TO INTENSIFY THE WEDGE. AFT 06Z...THERE IS SOME CONCERN
FOR WINTER PCPN AT LWB/BCB/ROA...AND POSSIBLY LYH IN THE FORM OF
SN/PL. DO EXPECT ACCUMULATING SNOW AT LWB...BUT ANY WINTER PCPN
FOR ROA/BCB SHOULD BE CONFINED TO THE 08Z-14Z TIME FRAME AND ONLY
LIMITED ACCUMULATION EXPECTED BEFORE PCPN CHANGES BACK TO -RA.
EXTENDED AVIATION DISCUSSION...
SUNDAY THROUGH WEDNESDAY CAN BEST CHARACTERIZED AS UNSETTLED. THE
FRONTAL BOUNDARY WILL NOT COMPLETELY CLEAR THE AREA UNTIL TUESDAY
MORNING. UNTIL THEN PERIODS OF RAIN AND LOW CEILINGS WILL BRING
EXTENDED PERIODS OF MVFR/IFR CONDITIONS TO ALL TAF LOCATIONS.
CONDITIONS WILL IMPROVE DRAMATICALLY BY TUESDAY AFTERNOON AND LAST
THROUGH WEDNESDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...JC/RAB
AREA FORECAST DISCUSSION
NWS SPOKANE WA
906 PM PDT Mon Mar 18 2013
.SYNOPSIS...
Active March weather will continue with cool, breezy and showery
conditions. After the showers decrease this evening, a vigorous
storm system will bring rain, snow, and windy conditions to the
Pacific Northwest Wednesday into Wednesday night. Cool and showery
conditions are expected Thursday into the upcoming weekend.
&&
.DISCUSSION...
Update: general forecast is on track save for a minor adjustments.
Winds remain locally breezy but trends and RAP guidance continues
to indicate winds abating, with the slackening gradients and
decoupling. I adjust overnight low up a 2-3 degrees where winds
remain a bit breezier, toward the basin, and up about a degree
based on newest guidance and trends. Otherwise the isolated
showers are dissipating through the Panhandle this hour and
should largely be winding down, save for perhaps around the
Panhandle mountains (closer to the MT border) where the mean
northwest flow linger.
The next system is on the approach and newest guidance continues to
the lower level flow turning easterly going into Tuesday. With
this evening`s 00Z sounding showing some drying and subsidence, it
will take time for the atmosphere to moisten up again before the
next threat of precipitation really gets going. So much of Tuesday
looks dry.
By Tuesday night into Wednesday the incoming system taps some
moisture (with precipitable water values rising to around 150% of
normal). The system appears to have a "one-two" punch. First the
leading warm front and weakening mid-level wave come in Tuesday
night into early Wednesday morning, with the first precipitation
peak. Second, after a strictly relative-lull going into mid-
morning, the more dynamic cold front and negatively- tilted upper
wave coming through on Wednesday, with precipitation rates for the
entire system peaking around Wednesday afternoon.
With some exceptions, snow levels are expected to rise to around
2500 to 5000 feet. This is supported by 850mb temperatures in the
lower to mid-single digits (Celsius) and a stout southerly flow
(850mb winds around 20-40 kts). The exceptions will be around the
Cascades through Canadian border counties, especially for Tuesday
night/early Wednesday morning. This includes the Wenatchee area
through Okanogan Valley. A southeast flow will promote cold air
damming, with 850mb temps around 0 to -3C. With this set-up and
the potential for wet-bulb cooling, snow levels here will be closer
to valley floors.
Thus some snow accumulations are possible in these areas, which
may make the Wednesday morning commute slick and slower. The
mountain areas and passes may also see some moderate accumulations.
By late morning to early afternoon snow levels here are also
expected to rise out of the valleys. Before then, however, some
highlights may be needed. /J. Cote`
&&
.AVIATION...
00Z TAFS: Upper wave exits tonight, with a brief break coming
Tuesday before a wetter system approaches Tuesday night. Look
widely scattered to isolated snow showers this evening, before
02-04z. Isolated embedded thunderstorms are possible around the
Panhandle, generally away from TAF sites, before sunset. Breezy
conditions will also abate after 02-06Z, with KEAT expected to be
the last to see winds abate. Tuesday will be dry, but clouds will
be on the increase. The primary threat of precipitation will come
after 00Z Wednesday (Tuesday evening). /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 24 49 37 51 32 46 / 10 0 80 90 40 30
Coeur d`Alene 24 48 35 49 31 45 / 10 0 80 100 60 40
Pullman 26 51 37 51 32 43 / 10 10 80 90 40 40
Lewiston 31 57 39 58 36 49 / 10 10 60 80 40 30
Colville 21 51 32 50 29 48 / 10 0 80 90 40 30
Sandpoint 22 44 32 47 29 44 / 20 0 80 100 70 50
Kellogg 22 44 32 46 29 40 / 40 0 80 100 80 50
Moses Lake 25 54 36 56 33 51 / 0 10 70 60 10 10
Wenatchee 29 50 35 54 32 49 / 0 30 70 60 10 10
Omak 25 50 32 54 29 49 / 0 10 80 80 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1035 PM PDT Sat Mar 16 2013
.SYNOPSIS...
Breezy to windy conditions and colder temperatures will arrive
tonight as a cold front sweeps through the Inland Northwest. The
mountains will receive several inches of snow tonight into Sunday.
Breezy conditions will persist into Monday and the mountains will
continue to receive rain and snow showers. A break in the active
weather regime is expected on Tuesday before another strong storm
system brings wet and windy weather for Wednesday.
&&
.DISCUSSION...
Valley rain and mountain snow showers continue across the Inland
Northwest tonight. There were a few lightning strikes across the
upper Columbia Basin and the northeast zones as the cold front
moved through. There were a couple reports of small hail and gusty
winds with the thunderstorms. The convective showers will be
limited to extreme northeast WA and the northern panhandle of
Idaho through about 10 pm. There is still a slight chance of a
rumble or two of thunder with these showers but this will be very
localized and will be handled with NOWcasts. The focus for post
frontal snow showers will be on the Cascade Crest and the Puget
Sound convergence zone along with the north Idaho mts and NE
Blues. The HRRR has a pretty good handle on the precip so far,
including the Puget Sound Convergence Zone and the area of showers
headed for the NE Blue Mts. The afternoon forecast package was
leaning toward this model and remains in good shape. No big
changes for the evening update. /Kelch
&&
.AVIATION...
06Z TAFS: Scattered valley rain showers will transition to
snow showers for the Idaho panhandle overnight behind the cold
front. Windy conditions will continue overnight. Gusts of 30kts
or more will be possible at Pullman through the night with gusts
of 22kt to 27kt common at KGEG, KCOE, KMWH and KEAT. Instability
rain and snow showers will be possible again Sunday afternoon.
Gusty winds will continue through 02Z Monday then diminish. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 32 45 28 47 29 49 / 70 30 10 20 10 10
Coeur d`Alene 32 44 27 46 28 48 / 90 40 20 40 30 10
Pullman 30 43 28 46 30 50 / 70 30 20 20 10 20
Lewiston 36 50 33 53 34 57 / 40 30 10 10 10 10
Colville 33 48 29 51 28 55 / 50 30 10 20 10 10
Sandpoint 31 42 29 41 28 45 / 90 50 20 40 40 10
Kellogg 28 39 27 39 27 48 / 100 80 50 50 50 10
Moses Lake 35 52 32 56 31 56 / 20 10 0 0 10 30
Wenatchee 34 51 33 53 33 53 / 20 0 10 10 10 40
Omak 32 50 28 53 27 55 / 10 10 10 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
957 PM CDT MON MAR 18 2013
.UPDATE...DECIDED TO EXTEND THE WINTER WEATHER ADVISORY UNTIL 10
O`CLOCK TUESDAY FOR AREA SOUTH OF HIGHWAY 29 AND ALSO FOR DOOR
COUNTY AS MODELS FORECAST 40 KNOT WINDS AT 925 MPH LATER TONIGHT
AND TUESDAY MORNING WITH STRONG COLD ADVECTION AND FRESH SNOW ON
THE GROUND. CONSIDERABLE BLOWING AND DRIFTING SNOW POSSIBLE ON
NORTH SOUTH ROADS IN RURAL AREAS. WOULD NOT BE SURPRISED TO HAVE
SOME ROADS CLOSED WHERE DRIFTS ARE USUALLY A PROBLEM. DID NOT
INCLUDE THE AREAS FURTHER NORTH AS THE GRADIENT IS WEAKER AND THAT
REGION IS MOSTLY WOODED WHICH SLOWS DOWN THE WIND.
RDM
&&
.PREV DISCUSSION...ISSUED AT 719 PM CDT MON MAR 18 2013...
SHORT TERM...
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG
SHORTWAVE MOVING ACROSS THE NORTHERN MISSISSIPPI VALLEY EARLY THIS
AFTERNOON. AHEAD OF THIS TROUGH...A SHORTWAVE IMPULSE LIFTED
NORTH OVER SOUTHEAST WISCONSIN THIS MORNING AND ACROSS NORTHEAST
WISCONSIN THIS AFTERNOON. THIS IMPULSE HAS GENERATED WIDESPREAD
1/4SM TO 1/2SM ACROSS THE FOX VALLEY AND LAKESHORE. THE MAIN BAND
OF SNOW RIGHT AHEAD OF THE MAIN SHORTWAVE IS MOVING ACROSS CENTRAL
WISCONSIN WHERE MODERATE TO HEAVY SNOW IS ALSO OCCURRING. JUST
LEARNED ABOUT HWY 13 FROM WISCONSIN RAPIDS TO THE DELLS THAT TRAVEL
BECOMING NOT ADVISED. THOUGHT ABOUT EXPANDING THE ADVISORY ACROSS
THE REST OF THE AREA...BUT WEBCAMS FROM OSHKOSH SHOW LITTLE IN THE
WAY OF ACCUMULATIONS ON THEIR ROADWAYS. ROAD TEMPERATURES ARE A
COUPLE DEGREES WARMER THERE THAN FARTHER NORTH AND WEST...WHICH
COULD EXPLAIN PART OF THE ACCUMULATION DIFFERENCES. WITH THE BACK
EDGE OF THE HEAVIER SNOW NOT TOO FAR AWAY FROM THE SOUTHERN FOX
VALLEY...WILL KEEP THEM OUT OF THE ADVISORY. ROADS ARE BECOMING
SNOW COVERED IF NOT ALREADY SNOW COVERED FARTHER NORTH...SO WILL LET
THE ADVISORY GO AS PLANNED. WILL BUMP UP ACCUMS A BIT OVER NE
WISCONSIN. THE EVENING CREW MAY BE ABLE TO CANCEL THE ADVISORY
EARLY IF THE STRENGTHENING WINDS THIS EVENING DO NOT CREATE BLOWING
AND DRIFTING SNOW OF ANY SIGNIFICANCE.
TONIGHT...SHORTWAVE TROUGH WILL SWING NE ACROSS NORTHEAST WISCONSIN
THIS EVENING...AS ITS PARENT TROUGH CLOSES OFF OVER THE UPPER
PENINSULA AND LAKE SUPERIOR. THE LATEST HRRR SUGGESTS MOST OF THE
SYNOPTIC SNOW WILL HAVE PEELED OUT BY THE START OF THE
PERIOD...EXCEPT OVER NORTH-CENTRAL WISCONSIN WHERE DEEP MOISTURE
WILL HANG IN PLACE. WHERE THE UPPER AND MID-LEVEL MOISTURE DOES
DEPART...SNOW WILL DIMINISH TO FLURRIES OR PATCHY LIGHT FREEZING
DRIZZLE. WILL KEEP FZDZ WORDING AS CHANCE SINCE OBS UPSTREAM SEEM
WIDELY SCT...BUT POTENTIAL WILL BE THERE FOR A FEW HOURS.
WRAP-AROUND SNOW THEN TO RETURN LATE IN THE EVENING AND OVERNIGHT.
PLENTY OF LOW VSBYS IN SNOW SHOWERS OVER SOUTHERN MINNESOTA AND
EASTERN SD...SO DO NOT FEEL COMFORTABLE GOING JUST FLURRIES THOUGH
ACCUMS SHOULD ONLY BE A TENTH TO A HALF INCH. MEANWHILE...ARCTIC AIR
WILL BE PUNCHING ACROSS CENTRAL AND SOUTHERN WISCONSIN DURING THE
EVENING...AND INTO NORTHEAST WISCONSIN OVERNIGHT. AS THIS COLDER
AIR ARRIVES...WEST WEST WILL BE STRENGTHENING AND BECOME QUITE
GUSTY. THE BEST PRESSURE RISES WILL SPLIT THE AREA TO THE NORTH AND
SOUTH...BUT SOME GUSTS COULD STILL REACH 35 MPH. UPSTREAM OFFICES
CANCELLED THEIR BLIZZARD WARNINGS EARLY SINCE VSBYS WERE NOT LOW
ENOUGH...SUGGESTING BLOWING AND DRIFTING MAY NOT HAVE BEEN AS BIG A
FACTOR AS PREVIOUSLY THOUGHT. EARLY INDICATIONS OF SNOWFALL RATIOS
SO FAR TODAY ARE AROUND 10-12 TO 1...SO SNOW MAY BE TOO WET TO RESTRICT
VSBYS DUE TO BLOWING. WILL KEEP THE END TIME OF THE ADVISORY AT
03Z.
MONDAY...THE UPPER LOW WILL SHIFT A LITTLE NE OVER LAKE SUPERIOR
TOMORROW...TAKING SOME OF THE DEEPER MOISTURE WITH IT. SHOULD STILL
BE ENOUGH MOISTURE AND CYCLONIC FLOW ALOFT FOR OCCASIONAL SNOW
SHOWERS AND FLURRIES DURING THE MORNING...THEN BECOMING CONFINED TO
N-C WISCONSIN DURING THE AFTERNOON. WEST TO NORTHWEST WINDS WILL
REMAIN GUSTY...AND AN ISOLATED GUST UP TO 40 MPH WILL BE POSSIBLE IN
THE OPEN AREAS. TEMPS MAINLY IN THE MIDDLE 20S.
LONG TERM...
LITTLE CHANGE IN THE OVERALL...COLD...PATTERN FOR THE REGION
THROUGH THIS PERIOD. BROAD UPPER TROF OVER EASTERN TWO THIRDS OF
U.S. UPPER LOW TO SPIN OVER EASTERN LAKES INTO FRI...WHILE
MAIN STORM TRACK AND MOISTURE REMAINS TO OUR SOUTH. AT THE SURFACE
CANADIAN HIGH PRESSURE TO REMAIN OVER THE REGION.
TUE NIGHT INTO THU...
MAIN ISSUES LAKE EFFECT CHANCES AND CHANCE FOR SNOW SHOWERS ON
WED. PIECES OF ENERGY WILL CIRCULATE AROUND THE LOW THIS
PERIOD...BRINGING THREAT OF SNOW SHOWERS...FLURRIES. BEST CHANCE
TO BE ON WED AS UPPER TROF DROPS SOUTH OVER THE STATE.
HAVE TRIED TO ADD DEFINITION TO LAKE EFFECT CHANCES...WITH HIGHEST
CHANCES LATE TUE NIGHT INTO WEDNESDAY NIGHT AS HAVE SOME SYNOPTIC
LIFT AND MOISTURE. BY THE TIME THE WINDS BECOME MORE FAVORABLE
LATER WED NIGHT AND THU...SOUNDINGS SHOW LOWERING INVERSION
HEIGHTS AND DRYING WORKING IN.
THU NIGHT ONWARD...
EXTENDED MODELS STILL HAVING ISSUES LATER PERIODS...BRINGING LIGHT
QPF INTO THE REGION. STILL EXPECT ANY PACIFIC SYSTEM TO DIVE SE
AND PASS TOO FAR TO OUR SOUTH TO BRING ORGANIZED PCPN TO NE WI.
WITH HIGH PRESSURE AT SURFACE THROUGH PERIOD AND LIMITED MOISTURE
HAVE STAYED WITH DRY FORECAST. LLVL WINDS SHIFT TO NE FOR BRIEF
PERIOD SAT...WITH THOUGHTS OF LES OFF LAKE MICHIGAN. THOUGH AGAIN MOISTURE
AND INSTABILITY LIMITED. BELOW NORMAL TEMPERATURES EXPECTED TO
CONTINUE INTO THE LAST WEEK OF MARCH. HAVE AGAIN DROPPED FEW
DEGREES OFF GUIDANCE TEMPS FOR LATTER PERIODS.
&&
.AVIATION...LOTS OF VARIABILITY IN CIGS AND VSBYS THIS EVENING AS
LIGHT SNOW CONTINUES. IN ADDITION TO THE OCCASIONAL IFR CONDITIONS
THERE WILL ALSO BE INCREASING WESTERLY WINDS LATER TONIGHT WHICH
WILL PRODUCE BLOWING AND DRIFTING SNOW ON RUNWAYS AND TAXIWAYS.
CIGS OF 2500 TO 3500 FT EXPECTED TUESDAY WITH SCATTERED SNOW
SHOWERS WITH VSBYS OF 3 TO 5 MILES.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 AM CDT TUESDAY FOR WIZ022-030-
031-035>040-045-048>050-074.
WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR WIZ005-
010>013-018>021-073.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
719 PM CDT MON MAR 18 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG
SHORTWAVE MOVING ACROSS THE NORTHERN MISSISSIPPI VALLEY EARLY THIS
AFTERNOON. AHEAD OF THIS TROUGH...A SHORTWAVE IMPULSE LIFTED
NORTH OVER SOUTHEAST WISCONSIN THIS MORNING AND ACROSS NORTHEAST
WISCONSIN THIS AFTERNOON. THIS IMPULSE HAS GENERATED WIDESPREAD
1/4SM TO 1/2SM ACROSS THE FOX VALLEY AND LAKESHORE. THE MAIN BAND
OF SNOW RIGHT AHEAD OF THE MAIN SHORTWAVE IS MOVING ACROSS CENTRAL
WISCONSIN WHERE MODERATE TO HEAVY SNOW IS ALSO OCCURRING. JUST
LEARNED ABOUT HWY 13 FROM WISCONSIN RAPIDS TO THE DELLS THAT TRAVEL
BECOMING NOT ADVISED. THOUGHT ABOUT EXPANDING THE ADVISORY ACROSS
THE REST OF THE AREA...BUT WEBCAMS FROM OSHKOSH SHOW LITTLE IN THE
WAY OF ACCUMULATIONS ON THEIR ROADWAYS. ROAD TEMPERATURES ARE A
COUPLE DEGREES WARMER THERE THAN FARTHER NORTH AND WEST...WHICH
COULD EXPLAIN PART OF THE ACCUMULATION DIFFERENCES. WITH THE BACK
EDGE OF THE HEAVIER SNOW NOT TOO FAR AWAY FROM THE SOUTHERN FOX
VALLEY...WILL KEEP THEM OUT OF THE ADVISORY. ROADS ARE BECOMING
SNOW COVERED IF NOT ALREADY SNOW COVERED FARTHER NORTH...SO WILL LET
THE ADVISORY GO AS PLANNED. WILL BUMP UP ACCUMS A BIT OVER NE
WISCONSIN. THE EVENING CREW MAY BE ABLE TO CANCEL THE ADVISORY
EARLY IF THE STRENGTHENING WINDS THIS EVENING DO NOT CREATE BLOWING
AND DRIFTING SNOW OF ANY SIGNIFICANCE.
TONIGHT...SHORTWAVE TROUGH WILL SWING NE ACROSS NORTHEAST WISCONSIN
THIS EVENING...AS ITS PARENT TROUGH CLOSES OFF OVER THE UPPER
PENINSULA AND LAKE SUPERIOR. THE LATEST HRRR SUGGESTS MOST OF THE
SYNOPTIC SNOW WILL HAVE PEELED OUT BY THE START OF THE
PERIOD...EXCEPT OVER NORTH-CENTRAL WISCONSIN WHERE DEEP MOISTURE
WILL HANG IN PLACE. WHERE THE UPPER AND MID-LEVEL MOISTURE DOES
DEPART...SNOW WILL DIMINISH TO FLURRIES OR PATCHY LIGHT FREEZING
DRIZZLE. WILL KEEP FZDZ WORDING AS CHANCE SINCE OBS UPSTREAM SEEM
WIDELY SCT...BUT POTENTIAL WILL BE THERE FOR A FEW HOURS.
WRAP-AROUND SNOW THEN TO RETURN LATE IN THE EVENING AND OVERNIGHT.
PLENTY OF LOW VSBYS IN SNOW SHOWERS OVER SOUTHERN MINNESOTA AND
EASTERN SD...SO DO NOT FEEL COMFORTABLE GOING JUST FLURRIES THOUGH
ACCUMS SHOULD ONLY BE A TENTH TO A HALF INCH. MEANWHILE...ARCTIC AIR
WILL BE PUNCHING ACROSS CENTRAL AND SOUTHERN WISCONSIN DURING THE
EVENING...AND INTO NORTHEAST WISCONSIN OVERNIGHT. AS THIS COLDER
AIR ARRIVES...WEST WEST WILL BE STRENGTHENING AND BECOME QUITE
GUSTY. THE BEST PRESSURE RISES WILL SPLIT THE AREA TO THE NORTH AND
SOUTH...BUT SOME GUSTS COULD STILL REACH 35 MPH. UPSTREAM OFFICES
CANCELLED THEIR BLIZZARD WARNINGS EARLY SINCE VSBYS WERE NOT LOW
ENOUGH...SUGGESTING BLOWING AND DRIFTING MAY NOT HAVE BEEN AS BIG A
FACTOR AS PREVIOUSLY THOUGHT. EARLY INDICATIONS OF SNOWFALL RATIOS
SO FAR TODAY ARE AROUND 10-12 TO 1...SO SNOW MAY BE TOO WET TO RESTRICT
VSBYS DUE TO BLOWING. WILL KEEP THE END TIME OF THE ADVISORY AT
03Z.
MONDAY...THE UPPER LOW WILL SHIFT A LITTLE NE OVER LAKE SUPERIOR
TOMORROW...TAKING SOME OF THE DEEPER MOISTURE WITH IT. SHOULD STILL
BE ENOUGH MOISTURE AND CYCLONIC FLOW ALOFT FOR OCCASIONAL SNOW
SHOWERS AND FLURRIES DURING THE MORNING...THEN BECOMING CONFINED TO
N-C WISCONSIN DURING THE AFTERNOON. WEST TO NORTHWEST WINDS WILL
REMAIN GUSTY...AND AN ISOLATED GUST UP TO 40 MPH WILL BE POSSIBLE IN
THE OPEN AREAS. TEMPS MAINLY IN THE MIDDLE 20S.
.LONG TERM...
LITTLE CHANGE IN THE OVERALL...COLD...PATTERN FOR THE REGION
THROUGH THIS PERIOD. BROAD UPPER TROF OVER EASTERN TWO THIRDS OF
U.S. UPPER LOW TO SPIN OVER EASTERN LAKES INTO FRI...WHILE
MAIN STORM TRACK AND MOISTURE REMAINS TO OUR SOUTH. AT THE SURFACE
CANADIAN HIGH PRESSURE TO REMAIN OVER THE REGION.
TUE NIGHT INTO THU...
MAIN ISSUES LAKE EFFECT CHANCES AND CHANCE FOR SNOW SHOWERS ON
WED. PIECES OF ENERGY WILL CIRCULATE AROUND THE LOW THIS
PERIOD...BRINGING THREAT OF SNOW SHOWERS...FLURRIES. BEST CHANCE
TO BE ON WED AS UPPER TROF DROPS SOUTH OVER THE STATE.
HAVE TRIED TO ADD DEFINITION TO LAKE EFFECT CHANCES...WITH HIGHEST
CHANCES LATE TUE NIGHT INTO WEDNESDAY NIGHT AS HAVE SOME SYNOPTIC
LIFT AND MOISTURE. BY THE TIME THE WINDS BECOME MORE FAVORABLE
LATER WED NIGHT AND THU...SOUNDINGS SHOW LOWERING INVERSION
HEIGHTS AND DRYING WORKING IN.
THU NIGHT ONWARD...
EXTENDED MODELS STILL HAVING ISSUES LATER PERIODS...BRINGING LIGHT
QPF INTO THE REGION. STILL EXPECT ANY PACIFIC SYSTEM TO DIVE SE
AND PASS TOO FAR TO OUR SOUTH TO BRING ORGANIZED PCPN TO NE WI.
WITH HIGH PRESSURE AT SURFACE THROUGH PERIOD AND LIMITED MOISTURE
HAVE STAYED WITH DRY FORECAST. LLVL WINDS SHIFT TO NE FOR BRIEF
PERIOD SAT...WITH THOUGHTS OF LES OFF LAKE MICHIGAN. THOUGH AGAIN MOISTURE
AND INSTABILITY LIMITED. BELOW NORMAL TEMPERATURES EXPECTED TO
CONTINUE INTO THE LAST WEEK OF MARCH. HAVE AGAIN DROPPED FEW
DEGREES OFF GUIDANCE TEMPS FOR LATTER PERIODS.
&&
.AVIATION...LOTS OF VARIABILITY IN CIGS AND VSBYS THIS EVENING AS
LIGHT SNOW CONTINUES. IN ADDITION TO THE OCCASIONAL IFR CONDITIONS
THERE WILL ALSO BE INCREASING WESTERLY WINDS LATER TONIGHT WHICH
WILL PRODUCE BLOWING AND DRIFTING SNOW ON RUNWAYS AND TAXIWAYS.
CIGS OF 2500 TO 3500 FT EXPECTED TUESDAY WITH SCATTERED SNOW
SHOWERS WITH VSBYS OF 3 TO 5 MILES.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 PM CDT THIS EVENING FOR WIZ005-
010>013-018>022-030-031-035>039-045-073-074.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
243 PM CDT SUN MAR 17 2013
.SHORT TERM...SUNDAY NIGHT AND MONDAY
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED ACROSS THE CENTRAL GREAT LAKES EARLY THIS AFTERNOON. LIGHT
EAST FLOW OFF LAKE MICHIGAN IS PUSHING CLOUDS AND FLURRIES INTO THE
SHORELINE AREAS...BUT TOO MUCH DRY AIR IN PLACE TO REACH THE FOX
VALLEY. THE NEXT STORM SYSTEM IS EMERGING INTO THE NORTHERN PLAINS
AND LOOKS FAIRLY IMPRESSIVE ON SATELLITE IMAGERY. AS THIS CYCLONE
MOVES ACROSS THE AREA TOMORROW...SNOW AMOUNTS AND HEADLINES ARE THE
MAIN FORECAST CONCERNS.
TONIGHT...HIGH PRESSURE WILL SLIDE TO NEW ENGLAND AS THE NEXT STORM
SYSTEM MOVES EAST ACROSS THE PLAINS. MID AND HIGH CLOUDS WILL BE ON
THE INCREASE THROUGH THE NIGHT...AS THE LOW LEVEL PRESSURE GRADIENT
TIGHTENS. AS A RESULT OF MORE CLOUDS AND WIND...TEMPS WILL BE
SIGNIFICANTLY WARMER THAN LAST NIGHT AND MAINLY IN THE TEENS. THE
12Z MODEL SUITE SHOWS A SIMILAR TIMING OF THE ARRIVAL OF THE PRECIP
COMPARED TO WHAT THE PREVIOUS SHIFT SHOWED IN THE FORECAST.
THEREFORE...WILL ONLY SHOW SMALL CHANCES SNEAKING INTO CENTRAL
WISCONSIN BETWEEN 09-12Z.
MONDAY...THE STRONG SHORTWAVE WILL SWING AROUND THE NORTHERN
MISSISSIPPI VALLEY AND BECOME NEGATIVELY TILTED AS IT REACHES
CENTRAL WISCONSIN BY 00Z TUESDAY. SURFACE LOW PRESSURE WILL SHIFT
EAST FROM NORTHERN MINNESOTA TO NORTHERN WISCONSIN DURING THIS SAME
TIME. AS THE PREVIOUS SHIFT MENTIONED...THE SHORTWAVE WILL BRING
STRONG DYNAMICS AND MIXING RATIOS OF ABOUT 3 G/KG...WHICH WILL BE
SUFFICIENT TO PRODUCE SNOWFALL RATES OF AROUND A HALF INCH TO UP TO
ONE INCH PER HOUR (FOR BRIEF PERIODS OF TIME). THE BAND OF SNOW
SHOULD BE PROGRESSIVE...HOWEVER...AND LAST FOR AROUND 6 HOURS OR
SO. IN ADDITION...THE DENDRITIC GROWTH ZONE IS PRETTY HIGH AND NOT
THAT THICK....AND SURFACE TEMPS WILL BE APPROACHING 32 DEGREES OVER
NE WISCONSIN. THEREFORE...EXPECT LOWER SNOWFALL RATIOS THAT WHAT
THE MODELS INDICATE (13-15 TO 1) AND MORE LIKE 10-13:1. WITH
WIDESPREAD QPF AROUND 0.25-0.35...THIS WOULD PUT SNOWFALL AMOUNTS
AROUND 2-4 INCHES FOR MOST LOCATIONS (HIGHER OVER CENTRAL
WISCONSIN). BECAUSE OF FAIRLY BEEFY SNOWFALL RATES DESPITE SOME
AREAS BEING MARGINAL FOR ADVISORY CRITERIA SNOW...WILL ISSUE A
WINTER WEATHER ADVISORY FOR AREAS EXCEPT THE SOUTHERN FOX VALLEY AND
CENTRAL LAKE MICHIGAN SHORELINE. WEST WINDS KICK UP LATE MONDAY
AFTERNOON AND INTO MONDAY EVENING...SO WILL EXTEND THE ADVISORY
THROUGH MID EVENING OR SO TO COVER BLOWING AND DRIFTING CONCERNS.
.LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY
PERIOD WILL BE DOMINATED BY BROAD TROF OVER THE CENTRAL US...WITH
WESTERLIES LYING OVER SOUTHERN HALF OF THE U.S. LOOK FOR PROGRESSIVE
PACIFIC SYSTEMS DIVING THRU THE PLAINS INTO SOUTHEAST U.S...LEAVING
NE WI DRY FOR THE MOST PART...WITH TEMPERATURES RUNNING WELL BELOW
NORMAL.
INITIALLY...UPPER LOW TO MOVE ACROSS THE NORTHERN GREAT LAKES MON
NIGHT. WRAP-AROUND MOISTURE AND CYCLONIC FLOW EXPECTED TO BRING
LIGHT SNOW ACROSS NE WI THRU AT LEAST THE FIRST HALF OF MONDAY NIGHT.
STRONG CAA AND GUSTY WEST WINDS EXPECTED MON NIGHT INTO TUE.
THOUGH WITH CLOUDS AND WINDS...BUMPED MIN TEMPS UP SLIGHTLY FROM
EARLIER SHIFT.
QUESTION THROUGH THE TUE THROUGH WED PERIOD...IS WAVES ROTATING
AROUND THE UPPER LOW AND CHANCE FOR LIGHT PCPN WITH EACH SYSTEM.
DID NOT MAKE CHANGE TO TUE FLURRY FORECAST...THOUGH POTENTIAL
EXIST FOR LIGHT SNOW ON WED...WITH TROF DROPPING SOUTH THROUGH
STATE.
LAKE EFFECT POSSIBLE TUE INTO THU WITH INCOMING COLD AIR MASS AND
MOISTURE CIRCULATING AROUND LOW...THOUGH WITH A W-NW WIND...THE
BETTER ACCUMULATION VALUES ARE EXPECTED TO STAY NORTH OF THE MI/WI
BORDER WITH A TENTH OR TWO OVER NW VILAS COUNTY POSSIBLE.
SOME WEAKENING OF THE BLOCKY PATTERN AT END OF MODEL RUN...THOUGH
NO GREAT WARM-UP IN SIGHT. SPRING POSTPONED FOR AT LEAST ANOTHER
WEEK. DROPPED MAX/MINS TO BELOW GUIDANCE VALUES AS CLIMO EXERTING
TOO MUCH INFLUENCE.
&&
.AVIATION...
A FEW MVFR CIGS WL LINGER ACRS THE N EARLY THIS MORNING. SOME MVFR
CIGS COULD DEVELOP OVER E-C WI LATER THIS MORNING AS WINDS SHIFT
E. OTHERWISE...VFR CONDITIONS EXPECTED. MUCH POORER FLIGHT
CONDITIONS ARE EXPECTED MON AS SNOW BAND MOVES ACRS THE AREA.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM CDT MONDAY FOR WIZ005-
010-018-019-030-031-035>037-045.
WINTER WEATHER ADVISORY FROM 10 AM TO 10 PM CDT MONDAY FOR
WIZ011>013-020>022-038-039-073-074.
&&
$$
MPC/TE
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
1057 PM PDT MON MAR 18 2013
.DISCUSSION...AS OF 9:00 PM PDT MONDAY...A SIGNIFICANT CHANGE
IN THE WEATHER PATTERN IS DEVELOPING TONIGHT WITH WARM FRONTAL
PROCESSES PRIMING THE ATMOSPHERE FOR THE INCOMING RAIN. DEW POINTS
ARE RISING...THE 00Z SOUNDING SHOWS A MOISTENING ATMOSPHERE AND
THE AMSU TPW SHOWS 0.75 TO 0.83 INCHES OF PRECIPITABLE WATER JUST
OFF THE NORTHERN AND CENTRAL CALIFORNIA COAST.
LOW CONFIDENCE IN THE CURRENT MODEL SOLUTIONS AS THEY ARE NOT
MATCHING UP TO WHAT IS CURRENTLY BEING OBSERVED. DOPPLER RADAR IS
CURRENTLY PICKING UP RETURNS OFF THE SONOMA AND MARIN COUNTY
COASTS WHICH WAS NOT DEPICTED BY THE GFS...NAM OR EURO. THE MOST
CURRENT HIGH RESOLUTION MODEL PRESENTLY AVAILABLE TO US...THE
RAP...DEPICT AN AREA OF MOISTURE APPROACHING THE COAST THIS
EVENING AND INTO TONIGHT. HOWEVER THE MOISTURE GRADUALLY
DISSIPATING AS IT NEARS THE COAST OVERNIGHT. THE RAP SHOWS LIGHT
PRECIP POSSIBLE OVER THE NORTHERN BORDER OF SONOMA COUNTY. WOULD
NOT RULE IT OUT AT THIS POINT. WILL NEED TO CLOSELY MONITOR THE
EVOLUTION OF THE APPROACHING LOW AND ASSOCIATED COLD FRONT
OVERNIGHT AND MAY NEED TO OVERHAUL THE FORECAST.
WILL HOLD OFF ON MAKING ANY SIGNIFICANT CHANGES TO THE FORECAST AND
WILL CONTINUE TO MONITOR.
FROM PREVIOUS DISCUSSION...HIGH CLOUDS CONTINUE TO STREAM
OVERHEAD AS MID/UPPER LEVEL MOISTURE CONTINUES TO FLOW THROUGH THE
"DIRTY RIDGE". WATER VAPOR IMAGERY IS INDC TWO SYSTEMS THAT WILL
HAVE AN EFFECT ON THE DISTRICTS WEATHER THE NEXT COUPLE OF
DAYS...ONE SYSTEM IS CENTERED NEAR 37/147 AND THE OTHER ONE IS
NEAR 57/150. THE SOUTHERN SYSTEM IS ENTRAINING SUBTROPICAL
MOISTURE WITH THE BLENDED AMSU SSM/I DATA INDC AS MUCH AS 1.8
INCHES OF TPW NEAR 26/142.
MODELS HAVE TRENDED SLOWER WITH THESE SYSTEMS AS WELL AS KEEPING
THEM OUT OF PHASE. THE NORTHERN SYSTEM WILL MOVE INTO THE PACIFIC
NORTHWEST WHEREAS THE SOUTHERN SYSTEM WILL WEAKEN AS IT MOVES TO
THE COAST. SINCE THE BEST DYNAMICS WILL BE WELL TO THE NORTH
OROGRAPHICS WILL BE THE MAIN LIFTING MECHANISM FOR RAIN. AS OF
NOW...IT LOOKS LIKE LIGHT RAIN WILL DEVELOP IN THE NORTH BAY
TUESDAY AFTN...SPREADING SOUTH TUESDAY NIGHT INTO WEDNESDAY. POST
FRONTAL SHOWERS WILL CONTINUE WEDNESDAY AFTN AND END EARLY
WEDNESDAY EVENING. RAINFALL TOTALS WILL BE LIGHT ACROSS THE
DISTRICT...WITH SOME LOCATIONS IN INTERIOR MONTEREY AND SAN BENITO
COUNTIES POSSIBLY NOT SEEING ANY RAIN AT ALL. THE WETTEST
LOCATIONS...IN THE NORTH BAY MOUNTAINS COULD GET AS MUCH AS 0.75
INCHES TOTAL...NOT VERY SIGNIFICANT. VALLEY LOCATIONS WILL GET
LESS THAN 0.50 INCHES OF RAIN TOTAL. BASICALLY...THIS WILL BE A
HIGH POP LOW QPF EVENT.
RIDGING WILL BUILD IN RAPIDLY THURSDAY...AND CONTINUING RIGHT INTO
THE EARLY PORTIONS OF NEXT WEEK. THIS WILL RESULT IN DRY WEATHER
WITH ABOVE NORMAL TEMPERATURES.
&&
.AVIATION...AS OF 11:00 PM PDT MONDAY...STORM SYSTEM STILL ON
TRACK TO IMPACT TERMINALS TOMORROW AFTERNOON THROUGH EARLY
WEDNESDAY MORNING. RADAR DOES SHOW SOME LIGHT RETURN RIGHT NOW
AROUND THE COAST SO A SPRINKLE COULD HIT OVERNIGHT. SOME LOW CIGS
DID BRIEFLY COME IN EARLIER, BUT THOSE ARE NOW GONE WITH VFR
ACROSS THE BOARD. POSSIBLE LOW CIGS COULD COME IN AGAIN AHEAD OF
THE RAIN...ESPECIALLY NEAR THE COAST. GUSTY WINDS DO NOT LOOK
LIKELY WITH THE FRONTAL PASSAGE ON TUESDAY. MODERATE CONFIDENCE.
VICINITY OF KSFO....VFR THROUGH THE NIGHT TONIGHT WITH RAIN
EXPECTED TO START TUESDAY AFTERNOON. WINDS SHOULD STAY UNDER 12 KT.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...TRICKY FOR MONTEREY BAY REGION
OVERNIGHT AS LOW CLOUDS BRIEFLY CAME IN BUT HAVE SKIES HAVE GONE
BACK TO VFR. MORE LOW CLOUDS COULD ROLL IN TONIGHT ALTHOUGH WILL
KEEP VFR GOING. RAIN WON`T HIT UNTIL TUESDAY EVENING. WINDS WILL
STAY UNDER 12 KT. LOW TO MODERATE CONFIDENCE.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...NONE.
$$
PUBLIC FORECAST: STROBIN
AVIATION/MARINE: CW
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AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
313 AM MDT TUE MAR 19 2013
.SHORT TERM...MAIN ISSUE THIS TODAY WILL BE FIRE WX POTENTIAL IN
THE NRN FOOTHILLS AND ALONG THE WY BORDER. LATEST RAP HAS
HUMIDITIES DROPPING BELOW 15% BY EARLY AFTN ALONG THE FRONT RANGE
AND IN THE NRN FOOTHILLS WITH GUSTY NWLY WINDS DEVELOPING. FIRE
WX MANAGERS INDICATE HIGH FIRE POTENTIAL IN THE NRN FOOTHILLS AND
FM NORTH OF DENVER TO THE WY BORDER. WITH THAT IN MIND WILL ISSUE
A RED FLAG WARNING NORTH OF A LINE FROM BOULDER TO DENVER UP TO
THE WY BORDER FM 18Z-00Z.
OTHERWISE THE FLOW ALOFT WILL REMAIN WNW WITH SOME HIGHER LEVEL
MOISTURE MOVING ACROSS PRODUCING SOME HI LVL CLOUD COVER. AT THE
SFC A COOL FNT WILL MOVE ACROSS THE FAR NERN PLAINS WHICH WILL
BRING IN SOME SLIGHTLY COOLER AIR. THUS WILL KEEP HIGHS IN THE
UPPER 40S OVER THE FAR NERN PLAINS WITH LOWER 50S ALONG THE FRONT
RANGE URBAN CORRIDOR. FOR TONIGHT OUTSIDE OF SOME MID AND HIGH
LEVEL CLOUDS IT WILL BE DRY. WINDS SHOULD DIE DOWN BY SUNSET WITH
AN INCREASE IN HUMIDITY LEVELS WHICH WILL DECREASE FIRE DANGER.
.LONG TERM...A PROGRESSIVE PATTERN THROUGH LATE WEEK AS WEDNESDAY
WILL SEE THE RIDGE ALOFT FLATTEN AS IT MOVES OVER COLORADO AND
ADJACENT REGIONS. WEDNESDAY SHOULD BE THE WARMEST DAY OF THE WEEK
AND RELATIVELY DRY WITH LESS WIND. HOWEVER...MOISTURE WILL BE
QUICKLY SPREADING INTO THE MOUNTAINS LATE WEDNESDAY AFTERNOON IN
ADVANCE OF NEXT WEAK WAVE IN THE NORTHWEST FLOW PATTERN. EXPECT
THE MOUNTAINS TO BENEFIT THE MOST WITH DECENT OROGRAPHIC FLOW AND
MODEST LAPSE RATES. THE UPPER LEVEL TROF WILL MOVE ACROSS COLORADO
ON THURSDAY WITH ASSOCIATED COLD FRONT ACROSS NORTHEAST COLORADO
LATE THURSDAY AFTERNOON WITH SCATTERED SHOWERS. SURFACE WIND IS
MAINLY DOWNSLOPE NORTHWEST WIND BUT ENOUGH INSTABILITY FOR
SCATTERED SHOWERS TO GENERATE.
THE MAIN QUESTION IN THE LONG TERM CONCERNS THE NEXT BIGGER UPPER
LOW WHICH IS FORECAST TO DEVELOP OVER WESTERN COLORADO EARLY
SATURDAY MORNING BEFORE MOVING INTO THE TEXAS PANHANDLE BY LATE
SATURDAY NIGHT. THE LONG RANGE MODELS HAVE SHOWN MORE CONSISTENCY
WITH THIS SCENARIO WHICH HAD BEEN A BIG CHANGE FROM THE MODEL
RUNS SEVERAL DAYS AGO. RIGHT NOW THE EUROPEAN AND CANADIAN RUNS
ARE SHOWING THE DEEPEST LOW NEAR THE 4 CORNERS WHILE THE GFS IS A
BIT MORE PROGRESSIVE AND MORE OF AN OPEN WAVE ACROSS COLORADO. IF
THE EUROPEAN AND FRIENDS VERIFY...IT COULD MEAN A POTENTIAL FOR
HEAVY SNOW ON SATURDAY OVER THE EAST SLOPES AND NORTHEAST PLAINS.
STILL A WAYS TO GO AS WOULD EXPECT FUTURE MODEL CORRECTIONS AS WE
GET CLOSER TO THE EVENT. CERTAINLY SOME POTENTIAL AND MAJOR
IMPACTS IF IT VERIFIES. WON`T CHANGE MUCH TO CURRENT ZONES WITH
CHANCE OF SNOW OVER ENTIRE AREA THROUGH EARLY IN THE WEEKEND. IF
CONSISTENCY CONTINUES WILL LIKELY INCREASE POPS IN LATER SHIFTS.
&&
.AVIATION...WINDS EARLY THIS MORNING HAVE BEEN WNW AROUND 10 KTS.
WITH NWLY LOW LVL FLOW OVER THE CHEYENNE RIDGE MAY SEE A LONGMONT
ANTI CYCLONE THRU LATE MORNING WITH WINDS BECOMING MORE NLY BY
15Z THRU MIDDAY. BY EARLY AFTN THE STRONGER FLOW ALOFT MAY MIX
DOWN TO THE SFC ALLOW FOR GUSTY NWLY WINDS TO DVLP WITH SPEEDS IN
THE 15-20 MPH RANGE WITH A FEW GUSTS TO 25 MPH. BY 00Z IT APPEARS
WINDS SHOULD DECREASE BACK TO 10-15 MPH. DURING THE EVENING A WK
FNT IS FCST TO BACKDOOR INTO THE AREA WITH WINDS BECOMING LIGHT
ELY WHICH GRADUALLY BECOME DRAINAGE AFTER MIDNIGHT. THERE IS VERY
LITTLE MOISTURE WITH THIS FNT SO DO NOT EXPECT ANY STRATUS
OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 6 PM MDT THIS EVENING FOR
COZ215-238-239-242-243.
&&
$$
SHORT TERM...RPK
LONG TERM....ENTREKIN
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS NEW YORK NY
603 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COASTAL LOW WILL PASS JUST SOUTH OF LONG ISLAND TODAY...THEN
MOVE FROM THE GULF OF MAINE TONIGHT INTO THE CANADIAN MARITIMES ON
WEDNESDAY. ANOTHER COASTAL LOW WILL DEVELOP OFF THE MID ATLANTIC
COAST WEDNESDAY NIGHT...AND TRACK WELL SOUTHEAST OF LONG ISLAND
THURSDAY AND WELL EAST OF CAPE COD THURSDAY NIGHT. WEAK HIGH
PRESSURE WILL BUILD IN ON FRIDAY AND REMAIN THROUGH THE WEEKEND.
LOW PRESSURE WILL PASS TO THE SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE IS NOW OFF THE SRN NJ COAST...AND LOOKS TO PASS JUST
S OF LONG ISLAND TOWARD NANTUCKET TODAY PER GREATEST 3-HOURLY
PRESSURE FALLS. MID LEVEL WARMING HAS FORCED P-TYPE OVER TO EITHER
RAIN OR FREEZING RAIN. LOW LEVEL WARMING ON E FLOW HAS CHANGED
PRECIP TO RAIN ALONG THE COAST AND IN NYC METRO...SO MOST
ADVISORIES IN THIS AREA WERE DROPPED EARLIER EXCEPT IN WESTERN
BERGEN/E PASSAIC... WHERE SOME FREEZING RAIN MAY OCCUR AS TEMPS
HOVER AROUND FREEZING FOR A WHILE.
AS FOR THE INTERIOR...SFC TEMPS REMAIN AT OR BELOW FREEZING...AND
FREEZING RAIN THERE COULD ACCRETE TO 1-2 TENTHS OF AN INCH. MANY
LOWER HUDSON VALLEY LOCATIONS HAVE ALREADY HAD UP TO 6 INCHES OF
SNOW...WHILE MOST OF SRN CT HAS SEEN 3-4 INCHES OF SNOWFALL. COMBO
OF ICE ATOP EARLIER SNOWFALL STILL COMMUTE JUSTIFIES KEEPING
WINTER STORM WARNINGS UP ACROSS THE INTERIOR BASED ON IMPACT.
PRECIP HAS BECOME MORE SPOTTY IN NATURE AT THIS TIME ACROSS
WESTERN SECTIONS...BUT MAY FILL IN AGAIN DURING THE MORNING AND
EARLY AFTERNOON AS A POTENT MID LEVEL VORTICITY MAX ROUNDS THE
BASE OF A CLOSED LOW CENTERED OVER THE UPPER GREAT LAKES AND MOVES
ACROSS THE LOCAL AREA. AFTER THIS VORTICITY PASSES...PRECIP SHOULD
END AND SKIES MAY BRIGHTEN DURING THE MID TO LATE AFTERNOON ON A
BRISK DOWNSLOPE W FLOW ACROSS NYC METRO AND THE LOWER HUDSON
VALLEY.
FOR HIGH TEMPS...BLENDED MAV/MET WITH COLDER 04Z RAP 2M
TEMPS...WITH HIGHS ONLY NEAR 40 INLAND WHICH COULD STILL BE A
LITTLE GENEROUS ESPECIALLY ACROSS SRN CT...AND MID 40S FOR NYC
METRO AND LONG ISLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FAST W TO WSW FLOW ALOFT TONIGHT AND THURSDAY AS CLOSED LOW BUILDS
INTO NORTHERN NEW ENGLAND...THEN SE CANADA. SHOULD BE DRY TONIGHT
AND THURSDAY WITH LITTLE IF ANY IN THE WAY OF FORCING - HOWEVER IF
UPPER TROUGH AXIS IS A TAD SLOWER IN PUSHING THROUGH THAN CURRENTLY
FORECAST COULD SEE SOME -SHSN ACROSS NORTHERN ZONES EARLY THIS
EVENING. FOR LOWS TONIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. USED A BLEND OF
MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM
850 HPA NEAR THE IMMEDIATE COAST...800 HPA ACROSS FAR INTERIOR
AREAS AND 825 HPA IN BETWEEN. THIS YIELDS HIGHS AROUND 10 DEGREES
BELOW NORMAL.
A COASTAL LOW DEVELOPS OFF THE MID ATLANTIC COAST WEDNESDAY NIGHT IN
RESPONSE TO A SOUTHERN STREAM SHORTWAVE MOVING OFFSHORE - THIS LOW
THEN MOVES WELL SE OF LONG ISLAND THURSDAY AND TO THE E OF CAPE COD
THURSDAY NIGHT AS THE NORTHERN STREAM CUTOFF LOW PIVOTS TO THE SE
INTO THE TRI-STATE. THE RESULT WILL BE CHANCE POPS COASTAL
AREAS/SLIGHT CHANCE POPS ELSEWHERE FOR LIGHT SNOW FROM LATE
WEDNESDAY NIGHT INTO THURSDAY EVENING - EXCEPT OVER FAR NW ZONES
WHERE ONLY COULD SEE A FEW FLURRIES.
USED A BLEND OF MAV/MET GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH
VALUES FORECAST TO BE AROUND 5 DEGREES BELOW NORMAL. U SED A
BLEND OF MIXING DOWN FROM 850 HPA NEAR THE COAST...800 HPA WELL
INLAND...AND 825 HPA IN BETWEEN...WITH A BLEND OF MAV/MET
GUIDANCE...AND NAM AND ECMWF 2-METER TEMPERATURES. THIS YIELDS
VALUES 10-15 DEGREES BELOW NORMAL. FOR LOWS THURSDAY NIGHT USED A
BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH VALUES AROUND
5 DEGREES BELOW NORMAL.
NW FLOW ALOFT FRIDAY WITH UPPER LOW OVER N AND E NEW ENGLAND - COULD
GET ENOUGH FORCING OUT OUT OF A PASSING SHORTWAVE IN THE AFTERNOON
TO WARRANT SLIGHT CHANCE POPS FOR -SHSN/-SHRA OVER FAR NW ZONES. FOR
HIGHS USED A BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH
VALUES AROUND 10 DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS BEGINNING TO COME INTO BETTER AGREEMENT WITH THE HANDLING
AND TIMING OF HIGH PRESSURE SYSTEM OVER THE COMING WEEKEND...AND
THE NEXT LOW PRESSURE SYSTEM FOR NEXT MONDAY/TUESDAY.
HIGH PRESSURE BUILDS TO THE SOUTH OVER THE NORTHEAST SATURDAY INTO
SUNDAY UNDER A BROAD UPPER LEVEL TROUGH. MULTIPLE SHORTWAVES
EXPECTED TO PASS THROUGH THE REGION WHILE ROTATING AROUND THE MAIN
UPPER LEVEL CLOSED LOW. DESPITE DECENT FORCING ASSOCIATED WITH EACH
PASSING WAVE...A PERSISTENT NORTHWESTERLY FLOW WILL KEEP A MAINLY
DRY VERTICAL COLUMN...RESULTING IN DRY CONDITIONS ACROSS THE AREA.
WHILE THE 12Z/18 RUNS HAD MUCH HIGHER DISCREPANCIES IN THE HANDLING
OF THE NEXT LOW...THE 00Z/19 RUNS ARE STARTING TO COME INTO BETTER
ALIGNMENT BUT STILL WITH SOME DIFFERENCES. LOW PRESSURE FORMS OVER
THE CENTRAL STATES ON SUNDAY...PROGRESSING TO THE EAST TO BEGIN
THE WEEK. 00Z ECMWF ACTUALLY THE MORE PROGRESSIVE OF THE SOLUTIONS...
WITH THE GFS LAGGING BEHIND WHILE DEVELOPING A SECONDARY LOW. THE
GFS THEN KEEPS THE UPPER LEVEL LOW FROM OVER THE WEEKEND NEARLY
STATIONARY...ALLOWING FOR POSSIBLE INTERACTION WITH THE NEXT LOW
TRAVERSING THE CENTRAL US...RESULTING IN MORE WIDESPREAD
PRECIPITATION. HOWEVER...THE PATTERN OF THE ECMWF KEEPS THE
TRAVERSING LOW TO THE SOUTH...BUILDING IN SUBSIDENCE OVER MOST OF
THE NORTHEAST...KEEPING THE HEAVIEST PRECIPITATION TO THE SOUTH.
BECAUSE OF THE MODEL SPREAD...CONTINUED THE SLIGHT CHANCE POPS FOR
MONDAY INTO TUESDAY.
GENERALLY USED A BLEND OF THE WPC AND MOS GUIDANCE FOR TEMPS THIS
WEEKEND INTO NEXT WEEK...WHICH KEEPS HIGH TEMPS SLIGHTLY BELOW
NORMAL AND OVERNIGHT LOWS RIGHT AROUND TO SLIGHTLY BELOW NORMAL.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE WILL TRACK FROM THE DELMARVA TO JUST SOUTHEAST OF
NYC THIS MORNING. THE LOW PRESSURE MOVES INTO COASTAL NEW ENGLAND
THIS EVENING. INITIALLY EASTERLY GUSTS OF AROUND 20 KT WILL LOWER
AND WINDS OVERALL BECOME LIGHT AND VARIABLE THIS MORNING BEFORE
BECOMING MORE WESTERLY BY THE AFTERNOON...GUSTING 20-25 KT LATE.
THERE IS SOME UNCERTAINTY ON WHEN EXACTLY THE WINDS TURN MORE
WESTERLY AND THE TIMING COULD BE OFF BY 1-2 HOURS.
ICING MAINLY RESTRICTED TO KSWF WHERE SNOW WILL BE CHANGING TO
SLEET AND FREEZING RAIN THIS MORNING. FOR KSWF...LOOKING FOR STORM
TOTAL SNOW OF ABOUT 7 INCHES WITH ABOUT A TENTH OF AN INCH OF ICE.
ELSEWHERE...THE PRECIP TYPE IS RAIN. ALL PRECIP BECOMES DRIZZLE
LATER THIS MORNING...LINGERING INTO THE AFTERNOON. MAINLY MVFR/IFR
CONDITIONS WITH SOME POCKETS OF LIFR WITH NO SUBSTANTIAL
IMPROVEMENT EXPECTED UNTIL WINDS BECOME MORE WESTERLY AND START
GUSTING LATE IN THE AFTERNOON GENERALLY AFTER 20Z. POSSIBLE VLIFR
POSSIBLE IN FOG THIS MORNING WHEN LOW IS WITHIN CLOSEST PROXIMITY
OF THE TERMINALS. VFR RETURNS BY THE EVENING WITH WEST WINDS
GUSTING TO 25-30 KT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
KLGA FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
KEWR FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LOW END IFR
CIGS COULD BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2
HOURS OFF. AMENDMENTS POSSIBLE.
KHPN FCSTER COMMENTS: THE TIMING OF LIFR CONDITIONS COULD BE OFF
BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KISP FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS
COULD BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS
OFF. AMENDMENTS POSSIBLE.
.OUTLOOK FOR 09Z WED THROUGH SAT...
.WED...GENERALLY VFR. W WINDS WITH GUSTS INTO THE LOWER 20 KT
RANGE ON WED.
.THU...CHANCE OF SUB-VFR IN LIGHT RAIN OR SNOW.
.FRI...VFR. GUSTY NW WINDS POSSIBLE.
.SAT...VFR.
&&
.MARINE...
NON ELEVATED OBSERVATIONS ACROSS THE COASTAL OCEAN WATERS INDICATE
THAT GALE FORCE GUSTS HAVE COME TO AN END - SO HAVE ALLOWED GALE
WARNING TO COME TO AN END AND HAVE REPLACED IT WITH A SMALL CRAFT
ADVISORY FOR ALL WATERS FOR TODAY. WHILE SHELTERED WATERS...
ESPECIALLY NY HARBOR AND PORTIONS OF W LONG ISLAND SOUND WILL
HAVE PERIODS OF WINDS BELOW SMALL CRAFT LEVELS - EXPECT THEM TO BE
RELATIVELY SHORT IN DURATION.
WINDS INCREASE TONIGHT AS COASTAL LOW DEEPENS TO THE EAST - SO
HAVE ISSUED A GALE WARNING FOR ALL WATERS FOR TONIGHT. GALE GUSTS
CONTINUE ON WEDNESDAY OVER EASTERN COASTAL OCEAN WATERS -
ANZ350-353 - WITH SMALL CRAFT CONDITIONS ELSEWHERE. THE PRESSURE
GRADIENT RELAXES OVER THE REGION WEDNESDAY NIGHT...WITH ALL WATERS
FALLING BELOW SCA LEVELS AFTER MIDNIGHT..AND CONTINUE ON THURSDAY.
WIND GUSTS ON THE COASTAL OCEAN WATERS COULD REACH 25 KT THURSDAY
NIGHT IN THE WAKE OF THE DEPARTING...BUT STRENGTHENING COASTAL
LOW...WITH SUB-SMALL CRAFT CONDITIONS ON THE REMAINDER OF THE WATERS.
FRIDAY WILL FEATURE SUB-SMALL CRAFT CONDITIONS ON ALL WATERS AS THE
PRESSURE GRADIENT RELAXES...EXCEPT FOR POSSIBLY SWELLS BRING SCA
SEAS TO THE TWO EASTERN COASTAL WATER ZONES.
GENERALLY EXPECTING SUB-SCA CONDITIONS THIS WEEKEND WITH HIGH
PRESSURE BUILDING INTO THE REGION. A BRIEF PERIOD OF INTERACTION
BETWEEN THE DEPARTING LOW AND APPROACHING HIGH FRI NIGHT COULD
INCREASE WINDS ENOUGH FROM THE NORTHWEST...COMBINED WITH COLD AIR
ADVECTION TO PRODUCE 25 KT GUSTS AND 5 FT SEAS ON THE OCEAN.
CONDITIONS THEN WILL DIMINISH BY SATURDAY.
POSSIBLE SCA CONDITIONS AGAIN NEXT MONDAY AND TUESDAY WITH THE NEXT
LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...
LIQUID EQUIVALENT STORM TOTAL QPF OF 1.00-1.25 INCHES EXPECTED.
PRECIP LIGHT ENOUGH AT THIS TIME THAT COMBINED LIGHT RAIN AND SNOW
MELT SHOULD NOT CAUSE MUCH IN THE WAY OF PROBLEMS.
DRY TONIGHT AND WEDNESDAY. THERE IS THE CHANCE FOR SOME LIGHT
PRECIPITATION FROM LATE WEDNESDAY NIGHT INTO THURSDAY EVENING
MAINLY OVER THE SE 1/2 OF THE TRI-STATE. NO HYDROLOGIC IMPACT
IS EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
CTZ005>008.
NY...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
NYZ067>070.
NJ...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR NJZ002.
WINTER WEATHER ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
NJZ004-103.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EDT WEDNESDAY FOR
ANZ330-335-338-340-345-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EDT WEDNESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...GOODMAN/MALOIT/SEARS
NEAR TERM...GOODMAN
SHORT TERM...MALOIT
LONG TERM...SEARS
AVIATION...JM
MARINE...MALOIT/SEARS
HYDROLOGY...GOODMAN
AREA FORECAST DISCUSSION
NWS NEW YORK NY
558 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COASTAL LOW WILL PASS JUST SOUTH OF LONG ISLAND TODAY...THEN
MOVE FROM THE GULF OF MAINE TONIGHT INTO THE CANADIAN MARITIMES ON
WEDNESDAY. ANOTHER COASTAL LOW WILL DEVELOP OFF THE MID ATLANTIC
COAST WEDNESDAY NIGHT...AND TRACK WELL SOUTHEAST OF LONG ISLAND
THURSDAY AND WELL EAST OF CAPE COD THURSDAY NIGHT. WEAK HIGH
PRESSURE WILL BUILD IN ON FRIDAY AND REMAIN THROUGH THE WEEKEND.
LOW PRESSURE WILL PASS TO THE SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE IS NOW OFF THE SRN NJ COAST...AND LOOKS TO PASS JUST
S OF LONG ISLAND TOWARD NANTUCKET TODAY PER GREATEST 3-HOURLY
PRESSURE FALLS. MID LEVEL WARMING HAS FORCED P-TYPE OVER TO EITHER
RAIN OR FREEZING RAIN. LOW LEVEL WARMING ON E FLOW HAS CHANGED
PRECIP TO RAIN ALONG THE COAST AND IN NYC METRO...SO MOST
ADVISORIES IN THIS AREA WERE DROPPED EARLIER EXCEPT IN WESTERN
BERGEN/E PASSAIC... WHERE SOME FREEZING RAIN MAY OCCUR AS TEMPS
HOVER AROUND FREEZING FOR A WHILE.
AS FOR THE INTERIOR...SFC TEMPS REMAIN AT OR BELOW FREEZING...AND
FREEZING RAIN THERE COULD ACCRETE TO 1-2 TENTHS OF AN INCH. MANY
LOWER HUDSON VALLEY LOCATIONS HAVE ALREADY HAD UP TO 6 INCHES OF
SNOW...WHILE MOST OF SRN CT HAS SEEN 3-4 INCHES OF SNOWFALL. COMBO
OF ICE ATOP EARLIER SNOWFALL STILL COMMUTE JUSTIFIES KEEPING
WINTER STORM WARNINGS UP ACROSS THE INTERIOR BASED ON IMPACT.
PRECIP HAS BECOME MORE SPOTTY IN NATURE AT THIS TIME ACROSS
WESTERN SECTIONS...BUT MAY FILL IN AGAIN DURING THE MORNING AND
EARLY AFTERNOON AS A POTENT MID LEVEL VORTICITY MAX ROUNDS THE
BASE OF A CLOSED LOW CENTERED OVER THE UPPER GREAT LAKES AND MOVES
ACROSS THE LOCAL AREA. AFTER THIS VORTICITY PASSES...PRECIP SHOULD
END AND SKIES MAY BRIGHTEN DURING THE MID TO LATE AFTERNOON ON A
BRISK DOWNSLOPE W FLOW ACROSS NYC METRO AND THE LOWER HUDSON
VALLEY.
FOR HIGH TEMPS...BLENDED MAV/MET WITH COLDER 04Z RAP 2M
TEMPS...WITH HIGHS ONLY NEAR 40 INLAND WHICH COULD STILL BE A
LITTLE GENEROUS ESPECIALLY ACROSS SRN CT...AND MID 40S FOR NYC
METRO AND LONG ISLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FAST W TO WSW FLOW ALOFT TONIGHT AND THURSDAY AS CLOSED LOW BUILDS
INTO NORTHERN NEW ENGLAND...THEN SE CANADA. SHOULD BE DRY TONIGHT
AND THURSDAY WITH LITTLE IF ANY IN THE WAY OF FORCING - HOWEVER IF
UPPER TROUGH AXIS IS A TAD SLOWER IN PUSHING THROUGH THAN CURRENTLY
FORECAST COULD SEE SOME -SHSN ACROSS NORTHERN ZONES EARLY THIS
EVENING. FOR LOWS TONIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. USED A BLEND OF
MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM
850 HPA NEAR THE IMMEDIATE COAST...800 HPA ACROSS FAR INTERIOR
AREAS AND 825 HPA IN BETWEEN. THIS YIELDS HIGHS AROUND 10 DEGREES
BELOW NORMAL.
A COASTAL LOW DEVELOPS OFF THE MID ATLANTIC COAST WEDNESDAY NIGHT IN
RESPONSE TO A SOUTHERN STREAM SHORTWAVE MOVING OFFSHORE - THIS LOW
THEN MOVES WELL SE OF LONG ISLAND THURSDAY AND TO THE E OF CAPE COD
THURSDAY NIGHT AS THE NORTHERN STREAM CUTOFF LOW PIVOTS TO THE SE
INTO THE TRI-STATE. THE RESULT WILL BE CHANCE POPS COASTAL
AREAS/SLIGHT CHANCE POPS ELSEWHERE FOR LIGHT SNOW FROM LATE
WEDNESDAY NIGHT INTO THURSDAY EVENING - EXCEPT OVER FAR NW ZONES
WHERE ONLY COULD SEE A FEW FLURRIES.
USED A BLEND OF MAV/MET GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH
VALUES FORECAST TO BE AROUND 5 DEGREES BELOW NORMAL. U SED A
BLEND OF MIXING DOWN FROM 850 HPA NEAR THE COAST...800 HPA WELL
INLAND...AND 825 HPA IN BETWEEN...WITH A BLEND OF MAV/MET
GUIDANCE...AND NAM AND ECMWF 2-METER TEMPERATURES. THIS YIELDS
VALUES 10-15 DEGREES BELOW NORMAL. FOR LOWS THURSDAY NIGHT USED A
BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH VALUES AROUND
5 DEGREES BELOW NORMAL.
NW FLOW ALOFT FRIDAY WITH UPPER LOW OVER N AND E NEW ENGLAND - COULD
GET ENOUGH FORCING OUT OUT OF A PASSING SHORTWAVE IN THE AFTERNOON
TO WARRANT SLIGHT CHANCE POPS FOR -SHSN/-SHRA OVER FAR NW ZONES. FOR
HIGHS USED A BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH
VALUES AROUND 10 DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS BEGINNING TO COME INTO BETTER AGREEMENT WITH THE HANDLING
AND TIMING OF HIGH PRESSURE SYSTEM OVER THE COMING WEEKEND...AND
THE NEXT LOW PRESSURE SYSTEM FOR NEXT MONDAY/TUESDAY.
HIGH PRESSURE BUILDS TO THE SOUTH OVER THE NORTHEAST SATURDAY INTO
SUNDAY UNDER A BROAD UPPER LEVEL TROUGH. MULTIPLE SHORTWAVES
EXPECTED TO PASS THROUGH THE REGION WHILE ROTATING AROUND THE MAIN
UPPER LEVEL CLOSED LOW. DESPITE DECENT FORCING ASSOCIATED WITH EACH
PASSING WAVE...A PERSISTENT NORTHWESTERLY FLOW WILL KEEP A MAINLY
DRY VERTICAL COLUMN...RESULTING IN DRY CONDITIONS ACROSS THE AREA.
WHILE THE 12Z/18 RUNS HAD MUCH HIGHER DISCREPANCIES IN THE HANDLING
OF THE NEXT LOW...THE 00Z/19 RUNS ARE STARTING TO COME INTO BETTER
ALIGNMENT BUT STILL WITH SOME DIFFERENCES. LOW PRESSURE FORMS OVER
THE CENTRAL STATES ON SUNDAY...PROGRESSING TO THE EAST TO BEGIN
THE WEEK. 00Z ECMWF ACTUALLY THE MORE PROGRESSIVE OF THE SOLUTIONS...
WITH THE GFS LAGGING BEHIND WHILE DEVELOPING A SECONDARY LOW. THE
GFS THEN KEEPS THE UPPER LEVEL LOW FROM OVER THE WEEKEND NEARLY
STATIONARY...ALLOWING FOR POSSIBLE INTERACTION WITH THE NEXT LOW
TRAVERSING THE CENTRAL US...RESULTING IN MORE WIDESPREAD
PRECIPITATION. HOWEVER...THE PATTERN OF THE ECMWF KEEPS THE
TRAVERSING LOW TO THE SOUTH...BUILDING IN SUBSIDENCE OVER MOST OF
THE NORTHEAST...KEEPING THE HEAVIEST PRECIPITATION TO THE SOUTH.
BECAUSE OF THE MODEL SPREAD...CONTINUED THE SLIGHT CHANCE POPS FOR
MONDAY INTO TUESDAY.
GENERALLY USED A BLEND OF THE WPC AND MOS GUIDANCE FOR TEMPS THIS
WEEKEND INTO NEXT WEEK...WHICH KEEPS HIGH TEMPS SLIGHTLY BELOW
NORMAL AND OVERNIGHT LOWS RIGHT AROUND TO SLIGHTLY BELOW NORMAL.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE WILL TRACK FROM THE DELMARVA TO JUST SOUTHEAST OF
NYC THIS MORNING. THE LOW PRESSURE MOVES INTO COASTAL NEW ENGLAND
THIS EVENING. INITIALLY EASTERLY GUSTS OF AROUND 20 KT WILL LOWER
AND WINDS OVERALL BECOME LIGHT AND VARIABLE THIS MORNING BEFORE
BECOMING MORE WESTERLY BY THE AFTERNOON...GUSTING 20-25 KT LATE.
THERE IS SOME UNCERTAINTY ON WHEN EXACTLY THE WINDS TURN MORE
WESTERLY AND THE TIMING COULD BE OFF BY 1-2 HOURS.
ICING MAINLY RESTRICTED TO KSWF WHERE SNOW WILL BE CHANGING TO
SLEET AND FREEZING RAIN THIS MORNING. ELSEWHERE...THE PRECIP TYPE
IS RAIN. ALL PRECIP BECOMES DRIZZLE LATER THIS MORNING...LINGERING
INTO THE AFTERNOON. MAINLY MVFR/IFR CONDITIONS WITH SOME POCKETS
OF LIFR WITH NO SUBSTANTIAL IMPROVEMENT EXPECTED UNTIL WINDS
BECOME MORE WESTERLY AND START GUSTING LATE IN THE AFTERNOON
GENERALLY AFTER 20Z. POSSIBLE VLIFR POSSIBLE IN FOG THIS MORNING
WHEN LOW IS WITHIN CLOSEST PROXIMITY OF THE TERMINALS. VFR RETURNS
BY THE EVENING WITH WEST WINDS GUSTING TO 25-30 KT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
KLGA FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
KEWR FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LOW END IFR
CIGS COULD BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2
HOURS OFF. AMENDMENTS POSSIBLE.
KHPN FCSTER COMMENTS: THE TIMING OF LIFR CONDITIONS COULD BE OFF
BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KISP FCSTER COMMENTS: THE TIMING OF IFR VSBYS AND LIFR CIGS
COULD BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS
OFF. AMENDMENTS POSSIBLE.
.OUTLOOK FOR 09Z WED THROUGH SAT...
.WED...GENERALLY VFR. W WINDS WITH GUSTS INTO THE LOWER 20 KT
RANGE ON WED.
.THU...CHANCE OF SUB-VFR IN LIGHT RAIN OR SNOW.
.FRI...VFR. GUSTY NW WINDS POSSIBLE.
.SAT...VFR.
&&
.MARINE...
NON ELEVATED OBSERVATIONS ACROSS THE COASTAL OCEAN WATERS INDICATE
THAT GALE FORCE GUSTS HAVE COME TO AN END - SO HAVE ALLOWED GALE
WARNING TO COME TO AN END AND HAVE REPLACED IT WITH A SMALL CRAFT
ADVISORY FOR ALL WATERS FOR TODAY. WHILE SHELTERED WATERS...
ESPECIALLY NY HARBOR AND PORTIONS OF W LONG ISLAND SOUND WILL
HAVE PERIODS OF WINDS BELOW SMALL CRAFT LEVELS - EXPECT THEM TO BE
RELATIVELY SHORT IN DURATION.
WINDS INCREASE TONIGHT AS COASTAL LOW DEEPENS TO THE EAST - SO
HAVE ISSUED A GALE WARNING FOR ALL WATERS FOR TONIGHT. GALE GUSTS
CONTINUE ON WEDNESDAY OVER EASTERN COASTAL OCEAN WATERS -
ANZ350-353 - WITH SMALL CRAFT CONDITIONS ELSEWHERE. THE PRESSURE
GRADIENT RELAXES OVER THE REGION WEDNESDAY NIGHT...WITH ALL WATERS
FALLING BELOW SCA LEVELS AFTER MIDNIGHT..AND CONTINUE ON THURSDAY.
WIND GUSTS ON THE COASTAL OCEAN WATERS COULD REACH 25 KT THURSDAY
NIGHT IN THE WAKE OF THE DEPARTING...BUT STRENGTHENING COASTAL
LOW...WITH SUB-SMALL CRAFT CONDITIONS ON THE REMAINDER OF THE WATERS.
FRIDAY WILL FEATURE SUB-SMALL CRAFT CONDITIONS ON ALL WATERS AS THE
PRESSURE GRADIENT RELAXES...EXCEPT FOR POSSIBLY SWELLS BRING SCA
SEAS TO THE TWO EASTERN COASTAL WATER ZONES.
GENERALLY EXPECTING SUB-SCA CONDITIONS THIS WEEKEND WITH HIGH
PRESSURE BUILDING INTO THE REGION. A BRIEF PERIOD OF INTERACTION
BETWEEN THE DEPARTING LOW AND APPROACHING HIGH FRI NIGHT COULD
INCREASE WINDS ENOUGH FROM THE NORTHWEST...COMBINED WITH COLD AIR
ADVECTION TO PRODUCE 25 KT GUSTS AND 5 FT SEAS ON THE OCEAN.
CONDITIONS THEN WILL DIMINISH BY SATURDAY.
POSSIBLE SCA CONDITIONS AGAIN NEXT MONDAY AND TUESDAY WITH THE NEXT
LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...
LIQUID EQUIVALENT STORM TOTAL QPF OF 1.00-1.25 INCHES EXPECTED.
PRECIP LIGHT ENOUGH AT THIS TIME THAT COMBINED LIGHT RAIN AND SNOW
MELT SHOULD NOT CAUSE MUCH IN THE WAY OF PROBLEMS.
DRY TONIGHT AND WEDNESDAY. THERE IS THE CHANCE FOR SOME LIGHT
PRECIPITATION FROM LATE WEDNESDAY NIGHT INTO THURSDAY EVENING
MAINLY OVER THE SE 1/2 OF THE TRI-STATE. NO HYDROLOGIC IMPACT
IS EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
CTZ005>008.
NY...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
NYZ067>070.
NJ...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR NJZ002.
WINTER WEATHER ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
NJZ004-103.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EDT WEDNESDAY FOR
ANZ330-335-338-340-345-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EDT WEDNESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...GOODMAN/MALOIT/SEARS
NEAR TERM...GOODMAN
SHORT TERM...MALOIT
LONG TERM...SEARS
AVIATION...JM
MARINE...MALOIT/SEARS
HYDROLOGY...GOODMAN
AREA FORECAST DISCUSSION
NWS NEW YORK NY
506 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COASTAL LOW WILL PASS JUST SOUTH OF LONG ISLAND TODAY...THEN
MOVE FROM THE GULF OF MAINE TONIGHT INTO THE CANADIAN MARITIMES ON
WEDNESDAY. ANOTHER COASTAL LOW WILL DEVELOP OFF THE MID ATLANTIC
COAST WEDNESDAY NIGHT...AND TRACK WELL SOUTHEAST OF LONG ISLAND
THURSDAY AND WELL EAST OF CAPE COD THURSDAY NIGHT. WEAK HIGH
PRESSURE WILL BUILD IN ON FRIDAY AND REMAIN THROUGH THE WEEKEND.
LOW PRESSURE WILL PASS TO THE SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE IS NOW OFF THE SRN NJ COAST...AND LOOKS TO PASS JUST
S OF LONG ISLAND TODAY PER GREATEST 3-HRLY PRESSURE FALLS
CENTERED NEAR 40N 71W ATTM. MID LEVEL WARMING IS IN PROCESS OF
CHANGING P-TYPE TO EITHER RAIN OR FREEZING RAIN...WITH JUST A
SLIVER OF LIGHT SNOWFALL HANGING ON ATTM IN ORANGE COUNTY WHICH
SHOULD ALSO CHANGE TO FREEZING RAIN SHORTLY. LOW LEVEL WARMING
ON E FLOW HAS CHANGED PRECIP TO RAIN ALONG THE COAST AND IN NYC
METRO...SO MOST ADVYS WILL BE DROPPED THERE EXCEPT FOR WRN
BERGEN/E PASSAIC...WHERE SOME FREEZING RAIN MAY OCCUR AS TEMPS
HOVER AROUND FREEZING FOR A WHILE.
AS FOR THE INTERIOR...MOS CONTINUES TO BE TOO QUICK TO WARM
THINGS UP AND USED 04Z RAP 2M TEMPS THROUGH THE MORNING...KEEPING
SFC TEMPS AOB FREEZING WHICH ALONG WITH WARMING ALOFT POINTS TO
SEVERAL HRS OF FREEZING RAIN INTO THE MORNING. MANY LOWER HUDSON
VALLEY LOCATIONS HAVE ALREADY HAD UP TO 6 INCHES OF SNOW...WHILE
MOST OF SRN CT HAS SEEN 3-4 INCHES OF SNOWFALL. THIS SNOWFALL PLUS
1/10 TO 1/4 INCH OF ICE INTO THE MORNING COMMUTE JUSTIFIES KEEPING
WINTER STORM WARNINGS UP ACROSS THE INTERIOR BASED ON IMPACT.
PRECIP HAS BECOME MORE SPOTTY IN NATURE ATTM ACROSS FAR NW
SECTIONS...BUT SHOULD FILL IN AGAIN DURING THE MORNING AND EARLY
AFTERNOON AS A POTENT MID LEVEL VORT MAX ROUNDS THE BASE OF A
CLOSED LOW CENTERED OVER THE UPPER GREAT LAKES AND MOVES ACROSS
THE LOCAL AREA. AFTER THIS VORT PASSES...PRECIP SHOULD END AND
SKIES MAY BRIGHTEN DURING THE MID TO LATE AFTERNOON ON A BRISK
DOWNSLOPE W FLOW ACROSS NYC METRO AND THE LOWER HUDSON VALLEY.
FOR HIGH TEMPS...BLENDED MAV/MET WITH COLDER 04Z RAP 2M
TEMPS...WITH HIGHS ONLY NEAR 40 INLAND WHICH COULD STILL BE A
LITTLE GENEROUS ESPECIALLY ACROSS SRN CT...AND MID 40S FOR NYC
METRO AND LONG ISLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FAST W TO WSW FLOW ALOFT TONIGHT AND THURSDAY AS CLOSED LOW BUILDS
INTO NORTHERN NEW ENGLAND...THEN SE CANADA. SHOULD BE DRY TONIGHT
AND THURSDAY WITH LITTLE IF ANY IN THE WAY OF FORCING - HOWEVER IF
UPPER TROUGH AXIS IS A TAD SLOWER IN PUSHING THROUGH THAN CURRENTLY
FORECAST COULD SEE SOME -SHSN ACROSS NORTHERN ZONES EARLY THIS
EVENING. FOR LOWS TONIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. USED A BLEND OF
MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM
850 HPA NEAR THE IMMEDIATE COAST...800 HPA ACROSS FAR INTERIOR AREAS
AND 825 HPA IN BETWEEN. THIS YIELDS HIGHS AROUND 10 DEGREES BELOW
NORMAL.
A COASTAL LOW DEVELOPS OFF THE MID ATLANTIC COAST WEDNESDAY NIGHT IN
RESPONSE TO A SOUTHERN STREAM SHORTWAVE MOVING OFFSHORE - THIS LOW
THEN MOVES WELL SE OF LONG ISLAND THURSDAY AND TO THE E OF CAPE COD
THURSDAY NIGHT AS THE NORTHERN STREAM CUTOFF LOW PIVOTS TO THE SE
INTO THE TRI-STATE. THE RESULT WILL BE CHANCE POPS COASTAL
AREAS/SLIGHT CHANCE POPS ELSEWHERE FOR LIGHT SNOW FROM LATE
WEDNESDAY NIGHT INTO THURSDAY EVENING - EXCEPT OVER FAR NW ZONES
WHERE ONLY COULD SEE A FEW FLURRIES.
USED A BLEND OF MAV/MET GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH
VALUES FORECAST TO BE AROUND 5 DEGREES BELOW NORMAL. USED A BLEND OF
MIXING DOWN FROM 850 HPA NEAR THE COAST...800 HPA WELL INLAND...AND
825 HPA IN BETWEEN...WITH A BLEND OF MAV/MET GUIDANCE...AND NAM AND
ECMWF 2-METER TEMPERATURES. THIS YIELDS VALUES 10-15 DEGREES BELOW
NORMAL. FOR LOWS THURSDAY NIGHT USED A BLEND OF MEX/MEX ENSEMBLE
MEAN/ECE/WPC GUIDANCE WITH VALUES AROUND 5 DEGREES BELOW NORMAL.
NW FLOW ALOFT FRIDAY WITH UPPER LOW OVER N AND E NEW ENGLAND - COULD
GET ENOUGH FORCING OUT OUT OF A PASSING SHORTWAVE IN THE AFTERNOON
TO WARRANT SLIGHT CHANCE POPS FOR -SHSN/-SHRA OVER FAR NW ZONES. FOR
HIGHS USED A BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH
VALUES AROUND 10 DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS BEGINNING TO COME INTO BETTER AGREEMENT WITH THE HANDLING
AND TIMING OF HIGH PRESSURE SYSTEM OVER THE COMING WEEKEND...AND
THE NEXT LOW PRESSURE SYSTEM FOR NEXT MONDAY/TUESDAY.
HIGH PRESSURE BUILDS TO THE SOUTH OVER THE NORTHEAST SATURDAY INTO
SUNDAY UNDER A BROAD UPPER LEVEL TROUGH. MULTIPLE SHORTWAVES
EXPECTED TO PASS THROUGH THE REGION WHILE ROTATING AROUND THE MAIN
UPPER LEVEL CLOSED LOW. DESPITE DECENT FORCING ASSOCIATED WITH EACH
PASSING WAVE...A PERSISTENT NORTHWESTERLY FLOW WILL KEEP A MAINLY
DRY VERTICAL COLUMN...RESULTING IN DRY CONDITIONS ACROSS THE AREA.
WHILE THE 12Z/18 RUNS HAD MUCH HIGHER DISCREPANCIES IN THE HANDLING
OF THE NEXT LOW...THE 00Z/19 RUNS ARE STARTING TO COME INTO BETTER
ALIGNMENT BUT STILL WITH SOME DIFFERENCES. LOW PRESSURE FORMS OVER
THE CENTRAL STATES ON SUNDAY...PROGRESSING TO THE EAST TO BEGIN
THE WEEK. 00Z ECMWF ACTUALLY THE MORE PROGRESSIVE OF THE SOLUTIONS...
WITH THE GFS LAGGING BEHIND WHILE DEVELOPING A SECONDARY LOW. THE
GFS THEN KEEPS THE UPPER LEVEL LOW FROM OVER THE WEEKEND NEARLY
STATIONARY...ALLOWING FOR POSSIBLE INTERACTION WITH THE NEXT LOW
TRAVERSING THE CENTRAL US...RESULTING IN MORE WIDESPREAD PCPN.
HOWEVER...THE PATTERN OF THE ECMWF KEEPS THE TRAVERSING LOW TO THE
SOUTH...BUILDING IN SUBSIDENCE OVER MOST OF THE
NORTHEAST...KEEPING THE HEAVIEST PCPN TO THE SOUTH. BECAUSE OF THE
MODEL SPREAD...CONTINUED THE SLIGHT CHC POPS FOR MONDAY INTO
TUESDAY.
GENERALLY USED A BLEND OF THE WPC AND MOS GUIDANCE FOR TEMPS THIS
WEEKEND INTO NEXT WEEK...WHICH KEEPS HIGH TEMPS SLIGHTLY BELOW
NORMAL AND OVERNIGHT LOWS RIGHT AROUND TO SLIGHTLY BELOW NORMAL.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE WILL TRACK FROM THE DELMARVA TO JUST SOUTHEAST OF
NYC THIS MORNING. THE LOW PRESSURE MOVES INTO COASTAL NEW ENGLAND
THIS EVENING. INITIALLY EASTERLY GUSTS OF AROUND 20 KT WILL LOWER
AND WINDS OVERALL BECOME LIGHT AND VARIABLE THIS MORNING BEFORE
BECOMING MORE WESTERLY BY THE AFTERNOON...GUSTING 20-25 KT LATE.
THERE IS SOME UNCERTAINTY ON WHEN EXACTLY THE WINDS TURN MORE
WESTERLY AND THE TIMING COULD BE OFF BY 1-2 HOURS.
ICING MAINLY RESTRICTED TO KSWF WHERE SNOW WILL BE CHANGING TO
SLEET AND FREEZING RAIN THIS MORNING. ELSEWHERE...THE PRECIP TYPE
IS RAIN. ALL PRECIP BECOMES DRIZZLE LATER THIS MORNING...LINGERING
INTO THE AFTERNOON. MAINLY MVFR/IFR CONDITIONS WITH SOME POCKETS
OF LIFR WITH NO SUBSTANTIAL IMPROVEMENT EXPECTED UNTIL WINDS
BECOME MORE WESTERLY AND START GUSTING LATE IN THE AFTERNOON
GENERALLY AFTER 20Z. POSSIBLE VLIFR POSSIBLE IN FOG THIS MORNING
WHEN LOW IS WITHIN CLOSEST PROXIMITY OF THE TERMINALS. VFR RETURNS
BY THE EVENING WITH WEST WINDS GUSTING TO 25-30 KT.
...NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: THE TIMING OF IFR VBSYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
KLGA FCSTER COMMENTS: THE TIMING OF IFR VBSYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
KEWR FCSTER COMMENTS: THE TIMING OF IFR VBSYS AND LIFR CIGS COULD
BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF.
AMENDMENTS POSSIBLE.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: THE TIMING OF IFR VBSYS AND LOW END IFR
CIGS COULD BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2
HOURS OFF. AMENDMENTS POSSIBLE.
KHPN FCSTER COMMENTS: THE TIMING OF LIFR CONDITIONS COULD BE OFF
BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KISP FCSTER COMMENTS: THE TIMING OF IFR VBSYS AND LIFR CIGS
COULD BE OFF BY 1-3 HOURS. WIND SHIFT TO NW COULD BE 1-2 HOURS
OFF. AMENDMENTS POSSIBLE.
.OUTLOOK FOR 09Z WED THROUGH SAT...
.WED...GENERALLY VFR. W WINDS WITH GUSTS INTO THE LOWER 20 KT
RANGE ON WED.
.THU...CHANCE OF SUB-VFR IN LIGHT RAIN OR SNOW.
.FRI...VFR. GUSTY NW WINDS POSSIBLE.
.SAT...VFR.
&&
.MARINE...
WILL MAINTAIN GALE WARNING THROUGH 6 AM OVER ALL WATERS - STILL
GUSTS TO GALE FORCE ONGOING BUT SHOULD TAPER OFF OVER THE NEXT 2-3
HOURS. MIGHT NEED TO EXTEND OVER FAR EASTERN OCEAN ZONE - BUT WILL
DECIDE CLOSER TO 6 AM.
FOR REMAINDER OF TODAY - WINDS SUBSIDE TO MAINLY SMALL CRAFT - WITH
SOME SUB-SMALL CRAFT CONDITIONS ON MORE PROTECTED WATERS. GALES THEN
RETURN FOR TONIGHT ON ALL WATERS WITH GALE GUSTS CONTINUING ON
WEDNESDAY OVER EASTERN COASTAL OCEAN WATERS WITH SMALL CRAFT
CONDITIONS ELSEWHERE.
THE PRESSURE GRADIENT CONTINUES TO RELAX OVER THE REGION WEDNESDAY
NIGHT...WITH ALL WATERS FALLING BELOW SCA LEVELS AFTER MIDNIGHT..AND
CONTINUE ON THURSDAY.
WIND GUSTS ON THE COASTAL OCEAN WATERS COULD REACH 25 KT THURSDAY
NIGHT IN THE WAKE OF THE DEPARTING...BUT STRENGTHENING COASTAL
LOW...WITH SUB-SMALL CRAFT CONDITIONS ON THE REMAINDER OF THE WATERS.
FRIDAY WILL FEATURE SUB-SMALL CRAFT CONDITIONS ON ALL WATERS AS THE
PRESSURE GRADIENT RELAXES...EXCEPT FOR POSSIBLY SWELLS BRING SCA
SEAS TO THE TWO EASTERN COASTAL WATER ZONES.
GENERALLY EXPECTING SUB-SCA CONDITIONS THIS WEEKEND WITH HIGH
PRESSURE BUILDING INTO THE REGION. A BRIEF PERIOD OF INTERACTION
BETWEEN THE DEPARTING LOW AND APPROACHING HIGH FRI NIGHT COULD
INCREASE WINDS ENOUGH FROM THE NORTHWEST...COMBINED WITH COLD AIR
ADVECTION TO PRODUCE 25 KT GUSTS AND 5 FT SEAS ON THE OCEAN.
CONDITIONS THEN WILL DIMINISH BY SATURDAY.
POSSIBLE SCA CONDITIONS AGAIN NEXT MONDAY AND TUESDAY WITH THE NEXT
LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...
LIQUID EQUIVALENT STORM TOTAL QPF OF 1.00-1.25 INCHES EXPECTED.
PRECIP LIGHT ENOUGH ATTM THAT COMBINED LIGHT RAIN AND SNOW MELT
SHOULD NOT CAUSE MUCH IN THE WAY OF PROBLEMS.
DRY TONIGHT AND WEDNESDAY. THERE IS THE CHANCE FOR SOME LIGHT
PRECIPITATION FROM LATE WEDNESDAY NIGHT INTO THURSDAY EVENING
MAINLY OVER THE SE 1/2 OF THE TRI-STATE. NO HYDROLOGIC IMPACT
IS EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
CTZ005>008.
NY...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
NYZ067>070.
NJ...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR NJZ002.
WINTER WEATHER ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
NJZ004-103.
MARINE...GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ330-335-
338-340-345-350-353-355.
&&
$$
SYNOPSIS...GOODMAN/MALOIT/SEARS
NEAR TERM...GOODMAN
SHORT TERM...MALOIT
LONG TERM...SEARS
AVIATION...JM
MARINE...MALOIT/SEARS
HYDROLOGY...GOODMAN
AREA FORECAST DISCUSSION
NWS NEW YORK NY
403 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COASTAL LOW WILL PASS JUST SOUTH OF LONG ISLAND TODAY...THEN
MOVE FROM THE GULF OF MAINE TONIGHT INTO THE CANADIAN MARITIMES ON
WEDNESDAY. ANOTHER COASTAL LOW WILL DEVELOP OFF THE MID ATLANTIC
COAST WEDNESDAY NIGHT...AND TRACK WELL SOUTHEAST OF LONG ISLAND
THURSDAY AND WELL EAST OF CAPE COD THURSDAY NIGHT. WEAK HIGH
PRESSURE WILL BUILD IN ON FRIDAY AND REMAIN THROUGH THE WEEKEND.
LOW PRESSURE WILL PASS TO THE SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE IS NOW OFF THE SRN NJ COAST...AND LOOKS TO PASS JUST
S OF LONG ISLAND TODAY PER GREATEST 3-HRLY PRESSURE FALLS
CENTERED NEAR 40N 71W ATTM. MID LEVEL WARMING IS IN PROCESS OF
CHANGING P-TYPE TO EITHER RAIN OR FREEZING RAIN...WITH JUST A
SLIVER OF LIGHT SNOWFALL HANGING ON ATTM IN ORANGE COUNTY WHICH
SHOULD ALSO CHANGE TO FREEZING RAIN SHORTLY. LOW LEVEL WARMING
ON E FLOW HAS CHANGED PRECIP TO RAIN ALONG THE COAST AND IN NYC
METRO...SO MOST ADVYS WILL BE DROPPED THERE EXCEPT FOR WRN
BERGEN/E PASSAIC...WHERE SOME FREEZING RAIN MAY OCCUR AS TEMPS
HOVER AROUND FREEZING FOR A WHILE.
AS FOR THE INTERIOR...MOS CONTINUES TO BE TOO QUICK TO WARM
THINGS UP AND USED 04Z RAP 2M TEMPS THROUGH THE MORNING...KEEPING
SFC TEMPS AOB FREEZING WHICH ALONG WITH WARMING ALOFT POINTS TO
SEVERAL HRS OF FREEZING RAIN INTO THE MORNING. MANY LOWER HUDSON
VALLEY LOCATIONS HAVE ALREADY HAD UP TO 6 INCHES OF SNOW...WHILE
MOST OF SRN CT HAS SEEN 3-4 INCHES OF SNOWFALL. THIS SNOWFALL PLUS
1/10 TO 1/4 INCH OF ICE INTO THE MORNING COMMUTE JUSTIFIES KEEPING
WINTER STORM WARNINGS UP ACROSS THE INTERIOR BASED ON IMPACT.
PRECIP HAS BECOME MORE SPOTTY IN NATURE ATTM ACROSS FAR NW
SECTIONS...BUT SHOULD FILL IN AGAIN DURING THE MORNING AND EARLY
AFTERNOON AS A POTENT MID LEVEL VORT MAX ROUNDS THE BASE OF A
CLOSED LOW CENTERED OVER THE UPPER GREAT LAKES AND MOVES ACROSS
THE LOCAL AREA. AFTER THIS VORT PASSES...PRECIP SHOULD END AND
SKIES MAY BRIGHTEN DURING THE MID TO LATE AFTERNOON ON A BRISK
DOWNSLOPE W FLOW ACROSS NYC METRO AND THE LOWER HUDSON VALLEY.
FOR HIGH TEMPS...BLENDED MAV/MET WITH COLDER 04Z RAP 2M
TEMPS...WITH HIGHS ONLY NEAR 40 INLAND WHICH COULD STILL BE A
LITTLE GENEROUS ESPECIALLY ACROSS SRN CT...AND MID 40S FOR NYC
METRO AND LONG ISLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FAST W TO WSW FLOW ALOFT TONIGHT AND THURSDAY AS CLOSED LOW BUILDS
INTO NORTHERN NEW ENGLAND...THEN SE CANADA. SHOULD BE DRY TONIGHT
AND THURSDAY WITH LITTLE IF ANY IN THE WAY OF FORCING - HOWEVER IF
UPPER TROUGH AXIS IS A TAD SLOWER IN PUSHING THROUGH THAN CURRENTLY
FORECAST COULD SEE SOME -SHSN ACROSS NORTHERN ZONES EARLY THIS
EVENING. FOR LOWS TONIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. USED A BLEND OF
MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM
850 HPA NEAR THE IMMEDIATE COAST...800 HPA ACROSS FAR INTERIOR AREAS
AND 825 HPA IN BETWEEN. THIS YIELDS HIGHS AROUND 10 DEGREES BELOW
NORMAL.
A COASTAL LOW DEVELOPS OFF THE MID ATLANTIC COAST WEDNESDAY NIGHT IN
RESPONSE TO A SOUTHERN STREAM SHORTWAVE MOVING OFFSHORE - THIS LOW
THEN MOVES WELL SE OF LONG ISLAND THURSDAY AND TO THE E OF CAPE COD
THURSDAY NIGHT AS THE NORTHERN STREAM CUTOFF LOW PIVOTS TO THE SE
INTO THE TRI-STATE. THE RESULT WILL BE CHANCE POPS COASTAL
AREAS/SLIGHT CHANCE POPS ELSEWHERE FOR LIGHT SNOW FROM LATE
WEDNESDAY NIGHT INTO THURSDAY EVENING - EXCEPT OVER FAR NW ZONES
WHERE ONLY COULD SEE A FEW FLURRIES.
USED A BLEND OF MAV/MET GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH
VALUES FORECAST TO BE AROUND 5 DEGREES BELOW NORMAL. USED A BLEND OF
MIXING DOWN FROM 850 HPA NEAR THE COAST...800 HPA WELL INLAND...AND
825 HPA IN BETWEEN...WITH A BLEND OF MAV/MET GUIDANCE...AND NAM AND
ECMWF 2-METER TEMPERATURES. THIS YIELDS VALUES 10-15 DEGREES BELOW
NORMAL. FOR LOWS THURSDAY NIGHT USED A BLEND OF MEX/MEX ENSEMBLE
MEAN/ECE/WPC GUIDANCE WITH VALUES AROUND 5 DEGREES BELOW NORMAL.
NW FLOW ALOFT FRIDAY WITH UPPER LOW OVER N AND E NEW ENGLAND - COULD
GET ENOUGH FORCING OUT OUT OF A PASSING SHORTWAVE IN THE AFTERNOON
TO WARRANT SLIGHT CHANCE POPS FOR -SHSN/-SHRA OVER FAR NW ZONES. FOR
HIGHS USED A BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH
VALUES AROUND 10 DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS BEGINNING TO COME INTO BETTER AGREEMENT WITH THE HANDLING
AND TIMING OF HIGH PRESSURE SYSTEM OVER THE COMING WEEKEND...AND
THE NEXT LOW PRESSURE SYSTEM FOR NEXT MONDAY/TUESDAY.
HIGH PRESSURE BUILDS TO THE SOUTH OVER THE NORTHEAST SATURDAY INTO
SUNDAY UNDER A BROAD UPPER LEVEL TROUGH. MULTIPLE SHORTWAVES
EXPECTED TO PASS THROUGH THE REGION WHILE ROTATING AROUND THE MAIN
UPPER LEVEL CLOSED LOW. DESPITE DECENT FORCING ASSOCIATED WITH EACH
PASSING WAVE...A PERSISTENT NORTHWESTERLY FLOW WILL KEEP A MAINLY
DRY VERTICAL COLUMN...RESULTING IN DRY CONDITIONS ACROSS THE AREA.
WHILE THE 12Z/18 RUNS HAD MUCH HIGHER DISCREPANCIES IN THE HANDLING
OF THE NEXT LOW...THE 00Z/19 RUNS ARE STARTING TO COME INTO BETTER
ALIGNMENT BUT STILL WITH SOME DIFFERENCES. LOW PRESSURE FORMS OVER
THE CENTRAL STATES ON SUNDAY...PROGRESSING TO THE EAST TO BEGIN
THE WEEK. 00Z ECMWF ACTUALLY THE MORE PROGRESSIVE OF THE SOLUTIONS...
WITH THE GFS LAGGING BEHIND WHILE DEVELOPING A SECONDARY LOW. THE
GFS THEN KEEPS THE UPPER LEVEL LOW FROM OVER THE WEEKEND NEARLY
STATIONARY...ALLOWING FOR POSSIBLE INTERACTION WITH THE NEXT LOW
TRAVERSING THE CENTRAL US...RESULTING IN MORE WIDESPREAD PCPN.
HOWEVER...THE PATTERN OF THE ECMWF KEEPS THE TRAVERSING LOW TO THE
SOUTH...BUILDING IN SUBSIDENCE OVER MOST OF THE
NORTHEAST...KEEPING THE HEAVIEST PCPN TO THE SOUTH. BECAUSE OF THE
MODEL SPREAD...CONTINUED THE SLIGHT CHC POPS FOR MONDAY INTO
TUESDAY.
GENERALLY USED A BLEND OF THE WPC AND MOS GUIDANCE FOR TEMPS THIS
WEEKEND INTO NEXT WEEK...WHICH KEEPS HIGH TEMPS SLIGHTLY BELOW
NORMAL AND OVERNIGHT LOWS RIGHT AROUND TO SLIGHTLY BELOW NORMAL.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE WILL TRACK FROM THE DELMARVA TO JUST SOUTHEAST OF
NYC INTO THIS MORNING. THE LOW PRESSURE MOVES INTO COASTAL NEW
ENGLAND IN THE EVENING. INITIALLY EASTERLY GUSTS OF AROUND 20 KT
WILL LOWER AND WINDS OVERALL BECOME LIGHT AND VARIABLE EARLY IN
THE MORNING BEFORE BECOMING MORE WESTERLY BY THE
AFTERNOON...GUSTING 20-25 KT LATE. THERE IS SOME UNCERTAINTY ON
WHEN EXACTLY THE WINDS TURN MORE WESTERLY AND THE TIMING COULD BE
OFF BY 1-2 HOURS.
PRECIP TYPE NOW RAIN FOR CITY AND COASTAL TERMINALS WITH MAINLY
FREEZING RAIN AND SLEET FOR KHPN AND KSWF. KSWF WILL STILL HAVE
SOME MORE SNOW BEFORE TRANSITIONING TO FREEZING RAIN AND SLEET.
FOR KSWF...SNOWFALL RATES AT KSWF 1/2 TO 1 INCH PER HOUR. ICING
EXPECTED THIS MORNING FOR KSWF.
ALL PRECIP BECOMES DRIZZLE LATER IN THE MORNING...LINGERING INTO
THE AFTERNOON. MAINLY MVFR/IFR CONDITIONS WITH SOME POCKETS OF
LIFR WITH NO SUBSTANTIAL IMPROVEMENT EXPECTED UNTIL WINDS BECOME
MORE WESTERLY AND START GUSTING LATE IN THE AFTERNOON GENERALLY
AFTER 20Z. POSSIBLE VLIFR POSSIBLE IN FOG THIS MORNING WHEN LOW
IS WITHIN CLOSEST PROXIMITY OF THE TERMINALS. VFR RETURNS BY THE
EVENING.
.OUTLOOK FOR 06Z WED THROUGH SAT...
.LATE TUE NGT...VFR WITH W WINDS 20-30KT.
.WED...GENERALLY VFR. W WINDS WITH GUSTS INTO THE LOWER 20 KT
RANGE ON WED.
.THU...CHANCE OF SUB-VFR IN LIGHT RAIN OR SNOW.
.FRI...VFR. GUSTY NW WINDS POSSIBLE.
.SAT...VFR.
&&
.MARINE...
WILL MAINTAIN GALE WARNING THROUGH 6 AM OVER ALL WATERS - STILL
GUSTS TO GALE FORCE ONGOING BUT SHOULD TAPER OFF OVER THE NEXT 2-3
HOURS. MIGHT NEED TO EXTEND OVER FAR EASTERN OCEAN ZONE - BUT WILL
DECIDE CLOSER TO 6 AM.
FOR REMAINDER OF TODAY - WINDS SUBSIDE TO MAINLY SMALL CRAFT - WITH
SOME SUB-SMALL CRAFT CONDITIONS ON MORE PROTECTED WATERS. GALES THEN
RETURN FOR TONIGHT ON ALL WATERS WITH GALE GUSTS CONTINUING ON
WEDNESDAY OVER EASTERN COASTAL OCEAN WATERS WITH SMALL CRAFT
CONDITIONS ELSEWHERE.
THE PRESSURE GRADIENT CONTINUES TO RELAX OVER THE REGION WEDNESDAY
NIGHT...WITH ALL WATERS FALLING BELOW SCA LEVELS AFTER MIDNIGHT..AND
CONTINUE ON THURSDAY.
WIND GUSTS ON THE COASTAL OCEAN WATERS COULD REACH 25 KT THURSDAY
NIGHT IN THE WAKE OF THE DEPARTING...BUT STRENGTHENING COASTAL
LOW...WITH SUB-SMALL CRAFT CONDITIONS ON THE REMAINDER OF THE WATERS.
FRIDAY WILL FEATURE SUB-SMALL CRAFT CONDITIONS ON ALL WATERS AS THE
PRESSURE GRADIENT RELAXES...EXCEPT FOR POSSIBLY SWELLS BRING SCA
SEAS TO THE TWO EASTERN COASTAL WATER ZONES.
GENERALLY EXPECTING SUB-SCA CONDITIONS THIS WEEKEND WITH HIGH
PRESSURE BUILDING INTO THE REGION. A BRIEF PERIOD OF INTERACTION
BETWEEN THE DEPARTING LOW AND APPROACHING HIGH FRI NIGHT COULD
INCREASE WINDS ENOUGH FROM THE NORTHWEST...COMBINED WITH COLD AIR
ADVECTION TO PRODUCE 25 KT GUSTS AND 5 FT SEAS ON THE OCEAN.
CONDITIONS THEN WILL DIMINISH BY SATURDAY.
POSSIBLE SCA CONDITIONS AGAIN NEXT MONDAY AND TUESDAY WITH THE NEXT
LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...
LIQUID EQUIVALENT STORM TOTAL QPF OF 1.00-1.25 INCHES EXPECTED.
PRECIP LIGHT ENOUGH ATTM THAT COMBINED LIGHT RAIN AND SNOW MELT
SHOULD NOT CAUSE MUCH IN THE WAY OF PROBLEMS.
DRY TONIGHT AND WEDNESDAY. THERE IS THE CHANCE FOR SOME LIGHT
PRECIPITATION FROM LATE WEDNESDAY NIGHT INTO THURSDAY EVENING
MAINLY OVER THE SE 1/2 OF THE TRI-STATE. NO HYDROLOGIC IMPACT
IS EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
CTZ005>008.
NY...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
NYZ067>070.
NJ...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR NJZ002.
WINTER WEATHER ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
NJZ004-103.
MARINE...GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ330-335-
338-340-345-350-353-355.
&&
$$
SYNOPSIS...GOODMAN/MALOIT/SEARS
NEAR TERM...GOODMAN
SHORT TERM...MALOIT
LONG TERM...SEARS
AVIATION...JM
MARINE...MALOIT/SEARS
HYDROLOGY...GOODMAN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1234 AM CDT TUE MAR 19 2013
.DISCUSSION...
1037 PM CDT
UPDATE FOR OVERNIGHT...
STRONG COLD AIR ADVECTION THAT STARTED THIS AFTERNOON AND
CONTINUED THROUGH THE EVENING WILL PERSIST OVERNIGHT.
BLUSTERY CONDITIONS WILL ALSO CONTINUE AS UNIDIRECTIONAL W WIND
IS MAINTAINED WITH SPEEDS OF 35 TO 40 KT UP TO BASE OF INVERSION
AT 3-4K FT.
STRONG MID LEVEL TROUGH HAS ROTATED N TO THE NORTHERN GREAT LAKES
THIS EVENING TAKING THE SIGNIFICANT SNOW AND SNOW SHOWERS WITH
IT. A SECOND BROADER MID LEVEL TROUGH IS CURRENTLY ROTATING E
OVER WI AND IL WITH A SOME FLURRIES AND A FEW SNOW SHOWERS. IN
THE WAKE OF THIS TROUGH SKIES HAVE BECOME PARTLY CLOUDY/MOSTLY
CLEAR ACROSS THE NW 1/3RD OF THE LOCAL FORECAST AREA AS
SUBSIDENCE IN THE LOWER LEVELS INCREASES. EXPECT THIS TREND TO
CONTINUE OVERNIGHT AS THE MID LEVEL TROUGH ROTATES NE PAST THE
AREA THOUGH WHEN THIS COLD JUST ABOUT ANY PATCH OF STRATOCU CAN
PRODUCE SOME FLURRIES.
AREAS OF MAINLY LIGHT SNOW ARE OVER PORTIONS OF MN AND WI UNDER
THE UPPER TROUGH THAT IS CLOSING OFF TO AN UPPER LOW. WITH THIS
UPPER LOW TO MOVE SLOWLY E OVERNIGHT THE ASSOCIATED CLOUDS AND
SNOW SHOWERS/FLURRIES ARE EXPECTED TO BE N OF THE WI STATE LINE.
TRS
//PREV DISCUSSION...
345 PM CDT
WHILE THE TRUE VERNAL EQUINOX ARRIVES WEDNESDAY...AND WE ARE THREE
WEEKS INTO METEOROLOGICAL WINTER...THE MAIN WEATHER HEADLINE THIS
WEEK WILL BE HOW UNSPRING-LIKE THE TEMPERATURES WILL BE. THIS
PRESENTS THE MAIN FORECAST CHALLENGE...ALONG WITH ANY SMALL
CHANCES FOR SNOW SHOWERS.
SYNOPSIS AND LATE THIS AFTERNOON...THE POTENT UPPER LEVEL LOW IS
MOVING EAST ACROSS MN THIS AFTERNOON...WITH THE MID-LEVEL JET AND
A VORT LOBE OF THE SYSTEM RUSHING EASTWARD OVER NORTHERN IL.
ENHANCEMENT ON THE LEADING EDGE OF THESE STEEPER MID-LEVEL LAPSE
RATES AND CONVERGENCE IS SEEN IN SNOW SHOWERS TRAVERSING NORTHEAST
ILLINOIS AS OF 3 PM. SPOTTIER HEAVIER SNOWFALL RATES WILL BE SEEN
IN THIS ACTIVITY AS IT DEPARTS. THE SURFACE ARCTIC FRONT OF THIS
SYSTEM IS CROSSING THE MISSISSIPPI RIVER AND WILL MOVE THROUGH THE
ENTIRE CWA BETWEEN 5 AND 9 PM. THIS WILL TURN THE SYNOPTIC PATTERN
TO ONE OF NORTHWEST FLOW AND COLD WHICH WILL CONTINUE TO REINFORCE
ITSELF THROUGH THE WEEK AS THE UPPER AND SURFACE LOWS EXPAND AND
SLOW ACROSS THE CENTRAL AND EASTERN GREAT LAKES. NUMEROUS SHORT
WAVE IMPULSES ARE EXPECTED TO RIDE AROUND THIS FEATURE WITH
MINIMAL CAUSES FOR SNOW...BUT EACH DRIVING COLD SURGES BACK INTO
THE AREA.
TONIGHT...SHORT TERM GUIDANCE IS IN GOOD AGREEMENT ON THE TIMING
OF THE ARCTIC FRONT THIS EVENING...ALONG WITH AGREEING THAT THE
STEEPENING OF THE LOW-LEVEL LAPSE RATES WILL LIKELY PRODUCE
SURFACE-BASED INSTABILITY. FORECAST SOUNDINGS FROM THE RAP YIELD
AROUND 50 J/KG OF MLCAPE ALONG AND IMMEDIATELY BEHIND THE FRONT.
THE SATURATED DEPTH AT THE TOP OF THIS MIXED LAYER IS QUITE
SHALLOW BUT MOST CONVECTIVE-ALLOWING ARW AND WRF GUIDANCE DO
CONTINUE TO PRODUCE A SPATTERING OF HIGHER REFLECTIVITY INDICATIVE
OF SNOW SHOWERS. WILL CARRY FLURRIES WITH A MENTION OF ISOLATED TO
SCATTERED SNOW SHOWERS.
THE FRONT WILL BRING BOTH STRONG HEIGHT AND PRESSURE RISES WHICH
ARE LINED UP WELL WITH A UNIDIRECTIONAL WIND COLUMN IN THE LOW-
LEVELS. THE TOP OF THE MIXED LAYER ON THE LATEST RAP GUIDANCE AS
WELL AS LOCAL ARW DOES YIELD 40 MPH GUSTS THIS EVENING. HAVE
INCLUDED SUCH GUSTS IMMEDIATELY BEHIND THE FRONT AND WOULD NOT BE
SURPRISED IF SOME PLACES IN THE SOUTHWEST FORECAST AREA COME IN A
BIT HIGHER. IF SNOW SHOWERS DO DEVELOP...SOME NOTABLE REDUCTIONS
IN VISIBILITY MAY BE SEEN DUE TO THE COMBINATION OF WINDS AND
SNOWFALL. WITH TEMPERATURES FALLING QUICKLY...WIND CHILLS IN THE
NORTHWEST FORECAST AREA LOOK TO ALREADY BE IN THE SINGLE DIGITS
BY 9 PM THIS EVENING. THIS DEGREE OF COLD AIR WILL SWEEP OVER THE
ENTIRE FORECAST AREA WITH EARLY MORNING TEMPERATURES IN THE MID
TEENS TOWARD ROCKFORD TO AROUND 20 EAST. THESE ARE ABOUT 10 TO 15
DEGREES BELOW NORMAL.
TUESDAY AND TUESDAY NIGHT...UPPER LEVEL HEIGHTS WILL NOT RISE ANY
ON TUE WITH CYCLONIC FLOW IN COMPLETE CONTROL. HOWEVER...MOST
SHORT WAVE ENERGY IS LIKELY TO REMAIN TO THE NORTH AND EAST...SO
IT IS POSSIBLE TO SEE A LITTLE SCATTERING IN SOUTHERN AREAS. WITH
THE FIRST COLD POCKET OF AIR SHIFTING SLIGHTLY EAST OF THE
AREA...TEMPERATURES SHOULD MAKE IT BACK CLOSE TO TODAYS HIGHS.
WIND CHILLS WILL REMAIN IN THE MID TEENS TO MID 20S HOWEVER. A
SECOND COLD FRONT PUSHES THROUGH TOMORROW NIGHT ASSOCIATED WITH A
SHORT WAVE ROTATING AROUND THE PARENT LOW. THIS APPEARS STARVED
FOR DEEP MOISTURE BUT THE COLD AIR WILL BRING LOW TEMPERATURES
EVEN COOLER TUE NIGHT AND WIND CHILLS BELOW ZERO FOR WED MORNING.
WEDNESDAY AND THURSDAY...DUE TO SUCCESSIVE COLD FRONTS AND LIKELY
BROKEN TO OVERCAST STRATOCU GIVEN FORECAST SOUNDINGS FOR
WED...THIS SHOULD BE THE DAY WITH THE COLDEST HIGH TEMPERATURE. IN
FACT...THE HIGH TEMPERATURE FORECAST /22/ REMAINS A TIED RECORD
LOW MAXIMUM FOR ROCKFORD ON MARCH 20TH. BACKWARD PARCEL
TRAJECTORIES FROM THE GFS IN THIS TIME INDICATE THE AIR MASS
SOURCE REGION TO BE THE NORTHERN PROVINCES OF CANADA...NOT A
TYPICAL SOURCE REGION FOR LATE MARCH FOR THIS AREA. DEPENDING ON
CLOUD COVER WED NIGHT AND THE AMOUNT WINDS EASE...LOWS MAY ALSO
APPROACH RECORD LEVELS AS THE NEXT COLD POCKET OF AIR MOVES OVER
THE AREA /850MB TEMPS OF -15C TO -17C/. THIS NEXT COLD SURGE
ACTUALLY REORIENTS THE LOW-LEVEL WINDS TO MORE NORTHERLY AND THUS
LOOKS TO PRESENT AT LEAST THE POTENTIAL FOR LAKE EFFECT SNOW TO
SHIFT TOWARD NORTHWEST INDIANA WED NIGHT INTO THU. HAVE UPPED
CHANCES THERE AND CERTAINLY ACCUMULATING SNOW OF A FEW INCHES OR
MORE COULD BE REALIZED IF A FOCUSED AREA DEVELOPS...WHICH SUCH
DETAILS BEING DIFFICULT TO DETERMINE AT THIS FORECAST DISTANCE.
THURSDAY WILL BEGIN TO SEE MARGINAL MODIFICATION IN TEMPERATURES.
BEYOND...WITH THE ACTIVE SHORT TERM NOT OVERLY MUCH TIME SPENT ON
THIS FORECAST PERIOD. THE PATTERN LOOKS TO REMAIN BLOCKED OVER THE
WEEKEND...WITH CONFIDENCE INCREASING SOMEWHAT THAT THE MAIN STORM
TRACK WILL BE TO THE SOUTH OF THE AREA AND GENERAL HIGH PRESSURE
IN THE REGION. HIGH TEMPERATURES LOOK TO BE 5 TO 10 DEGREES BELOW
NORMAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* VERY GUSTY WEST WINDS AROUND 30 KTS.
* HIGH END MVFR CEILINGS POSSIBLE THIS MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 06Z...
COLDER AIR CONTINUES TO PUSH SOUTHEAST ACROSS THE AREA EARLY THIS
MORNING AS A COLD FRONT EXITS TO THE SOUTHEAST. WITHIN THIS COLD
AIR...LOW LEVEL STRATUS AND STRONG WESTERLY WINDS PERSIST.
ALTHOUGH THERE MAY BE A BRIEF WINDOW IN THE NEAR TERM WHEN THE
CEILINGS SCATTER...UPSTREAM TRENDS SHOW THIS GAP FILLING BACK IN.
SO HAVE MAINTAINED BROKEN SKIES TO START TO THE FORECAST PERIOD
AND KEEP THEM THROUGH MID DAY...WITH ONLY SCATTER CLOUDS EXPECTED
THROUGH THE REMAINDER OF THE FORECAST PERIOD. IT DOES APPEAR THAT
CEILINGS MAY BE A TAD LOWER THAN PREVIOUSLY THOUGHT...AND SO HAVE
INTRODUCED HIGH END MVFR CEILINGS RANGING FROM 2500-2800 FT.
ALSO...ANY SNOW SHOWERS SHOULD BECOME MORE ISOLATED WITH TIME HERE
THIS MORNING. EXPECT WESTERLY WINDS TO PERSIST THROUGH THE
FORECAST PERIOD...GUSTING TO AROUND 30KT AT TIMES.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.
* MEDIUM HIGH CONFIDENCE WITH CEILING TRENDS.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY THROUGH SUNDAY...MVFR CIGS PSBL WED WITH GUSTY WEST WINDS.
OTHERWISE MAINLY VFR.
RATZER
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 PM
TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
338 AM CDT TUE MAR 19 2013
.DISCUSSION...
THE LATEST WATER VAPOR LOOP THIS MORNING AT 07Z SHOWS A WAVE MOVING
INTO SOUTHEAST WYOMING MOVING SOUTHEAST. THIS FEATURE WILL BRING
SOME ASCENT INTO NORTHEAST KANSAS BY LATE MORNING THROUGH THE
AFTERNOON HOURS. FORECAST SOUNDINGS FROM RAP SHOW STEEP LAPSE RATES
BELOW 750 MB THIS AFTERNOON. SOME ELEVATED INSTABILITY IS ALSO
PRESENT AND HAVE ADDED SHOWERS FOR PARTS OF NORTH CENTRAL AND
NORTHEAST KANSAS THIS AFTERNOON. LOW LEVELS ON SOUNDINGS SHOW THE
LOWER BOUNDARY LAYER MOISTENING WITH TIME. HIGHS TODAY WILL WARM
INTO THE MID 50S ACROSS THE SOUTHERN PORTIONS OF THE CWA WHILE THE
NORTHEAST CORNER WILL BE COOLEST WITH HIGHS IN THE UPPER 40S.
TONIGHT THROUGH WEDNESDAY BRINGS A DRY PERIOD TO THE FORECAST WITH A
NORTHWEST FLOW PATTERN ALOFT. TEMPERATURES WILL BE COOLER ON
WEDNESDAY WITH HIGH PRESSURE OVER NORTH CENTRAL AND NORTHEAST
KANSAS. EXPECTING HIGHS IN THE 40S.
WARM ADVECTION AND MOISTURE RETURN BEGINS IN EARNEST ALONG WITH
ISENTROPIC LIFT IN WESTERN AND CENTRAL KANSAS. BEST MOISTURE FOR ANY
PRECIPITATION REMAINS MAINLY WEST OF HIGHWAY 81 AND HAVE ADJUSTED
POPS WEDNESDAY NIGHT FURTHER WEST AND TRIMMED FURTHER EAST.
ISENTROPIC LIFT SHIFTS FURTHER EAST THURSDAY MORNING WITH MOISTURE
ADVECTION MAXIMIZED IN THE AFTERNOON HOURS. MODELS ARE IN AGREEMENT
WITH A SHORTWAVE MOVING OUT OF THE ROCKIES AND ACROSS KANSAS
THURSDAY AND THURSDAY NIGHT. BEST FOCUS FOR PRECIPITATION WILL BE
ACROSS EAST CENTRAL KANSAS. WITH WARMER TEMPERATURE PROFILES EXPECT
MORE OF A MIX OF PRECIPITATION TYPES THURSDAY AFTERNOON WITH THE
NORTHEAST REMAINING COLD ENOUGH FOR SNOW BUT EXPECT A MIX OF
RAIN...SLEET AND SNOW ACROSS NORTH CENTRAL AND NORTHEAST KANSAS.
WENT WITH A BLEND OF THE ECMWF...GEM AND GFS THROUGH FRIDAY THEN
WITH THE ECMWF AND GEM OVER THE WEEKEND. EXPECT THAT AROUND 2 INCHES
OR LESS OF ACCUMULATION AS THE SNOW WILL BE WET WITH SNOW/WATER
RATIO OF 6 TO 1 UP TO 9 TO 1...MELTING AND SOIL TEMPERATURES IN THE
MID AND UPPER 40S.
THE ECMWF AND GEM ARE IN GOOD AGREEMENT WITH THE UPPER TROUGH AXIS
MOVING THROUGH THE PLAINS ON SATURDAY NIGHT AND SUNDAY. THEY TAKE A
FURTHER SOUTH AND EAST TRACK THAN THE GFS WITH THE MID AND UPPER
LEVEL FEATURES. DEFORMATION ZONE WILL LAY ACROSS NORTHEAST AND EAST
CENTRAL KANSAS SATURDAY NIGHT AND SUNDAY. TEMPERATURE PROFILES
SUGGEST ALL SNOW SATURDAY NIGHT WITH A MIX OF RAIN AND SNOW SOUTH OF
I-70 SUNDAY WITH SNOW NORTH AND SOME ACCUMULATING SNOW IS POSSIBLE.
MODIFIED TEMPERATURES THURSDAY NIGHT AND FRIDAY NIGHT DUE TO CLOUDS
AND LIGHT PRECIPITATION. ANOTHER UPPER TROUGH IS FORECAST TO MOVE
INTO THE ROCKIES ON TUESDAY AND MAY BRING SOME MORE WINTER TYPE
WEATHER WITH IT.
53
&&
.AVIATION...
WILL MAINTAIN VFR TAF FCSTS THROUGH THE PERIOD WITH BKN-OVC CIGS
AROUND 7KFT WITH DRY AIR HOLDING JUST BLO THIS DECK. ALTHOUGH
SOME SLIGHT CHANCE FOR SPRINKLES/LIGHT RAIN SHOWERS AFT 18Z...THE
BETTER FOCUS APPEARS WILL BE NORTH OF THE TAF SITES. LIGHT EAST TO
NORTHEAST WINDS UNDER 8 KTS WILL CONTINUE.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
550 AM EDT TUE MAR 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 547 AM EDT TUE MAR 19 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW TROF EXTENDING FROM SCNTRL
CANADA INTO THE GREAT LAKES. SNOW IS DIMINISHING ACROSS UPPER MI AS
SHORTWAVE SLIPS E OF THE AREA. AT THE SFC...LOW PRES IS LOCATED OVER
CNTRL LAKE SUPERIOR. ON THE BACKSIDE OF THE LOW...STRONG NW WINDS
ARE DEVELOPING OVER FAR WRN LAKE SUPERIOR AND WILL BE REACHING UPPER
MI SHORTLY.
FCST THINKING HAS NOT CHANGED MUCH SINCE YESTERDAY. STRONG/GUSTY NW
WINDS WILL DEVELOP FROM W TO E TODAY AS SFC LOW PRES DRIFTS E. DEEP
MOISTURE/CONVERGENT CYCLONIC WNW FLOW AND INCREASINGLY COLDER AIR
WILL YIELD MDT/HVY LAKE ENHANCED SNOW DEVELOPING EARLY THIS MORNING
OVER THE W AND SPREADING TO AREAS FROM AROUND MUNISING EASTWARD LATE
MORNING/AFTN. WITH FCST SOUNDINGS SHOWING A DEEP DGZ OVER
GOGEBIC/ONTONAGON COUNTIES...SNOW SHOULD BE VERY HVY AT TIMES IN
THAT AREA TODAY. MEANWHILE...BEST LOW-LEVEL CONVERGENCE WILL SET UP
ACROSS NRN ONTONAGON COUNTY/SRN HALF OF HOUGHTON COUNTY FOR MUCH OF
TODAY/TONIGHT. BOTH FACTORS WILL RESULT IN GREATEST SNOW
ACCUMULATIONS TODAY/TONIGHT OCCURRING FROM THE HIGHER TERRAIN JUST N
OF KIWD TO THE PORCUPINE MOUNTAINS...ROCKLAND...TWIN LAKES AND
PAINESDALE. AMOUNTS UPWARDS OF 18 INCHES FROM 12Z TODAY-12Z WED SEEM
LIKELY IN THOSE AREAS...BUT WOULDN`T BE SURPRISED TO SEE MORE THAN
THAT. FARTHER N ON THE KEWEENAW...AMOUNTS WILL LIKELY TREND DOWN TO
A FOOT OR LESS UNDER WEAKER LOW-LEVEL CONVERGENCE. STRONG BOUNDARY
LAYER WINDS WILL SPREAD STEADIER SNOWS INTO BARAGA COUNTY WITH
ACCUMULATIONS LIKELY REACHING WARNING CRITERIA OVER HIGH TERRAIN. TO
THE E...AIR MASS WON`T BE QUITE AS COLD AND MAY RESULT IN DGZ BEING
DISPLACED A LITTLE ABOVE BEST UPWARD MOTION TODAY...BUT DGZ BECOMES
BETTER POSITIONED IN CONVECTIVE LAYER TONIGHT. LOW-LEVEL CONVERGENCE
IS NOT AS STRONG AS OVER THE W THROUGHOUT TODAY/TONIGHT. THESE
FACTORS SHOULD KEEP SNOW ACCUMULATIONS DOWN TO THE 6-12 INCH RANGE
BY WED MORNING WITH THE GREATEST AMOUNTS E OF MUNISING AND N/NW OF
KERY. WINDS WILL BE A SIGNIFICANT FACTOR. WITH GUSTS OF 30-40MPH...
ALONG LAKE SUPERIOR AND OVER THE KEWEENAW...BLSN WILL BE A MAJOR
ISSUE WITH WHITE-OUTS AT TIMES DUE TO HVY SNOW/BLSN. BLSN WILL BE
MOST SIGNIFICANT OVER THE KEWEENAW PENINSULA...WITH WORST CONDITIONS
THIS AFTN/EVENING.
AWAY FROM HEADLINE AREAS...-SN EARLY WILL TRANSITION TO SCT -SHSN.
DOWNSLOPE WWN WINDS WILL LIKELY BRING AN END TO -SHSN OVER THE
SCNTRL THIS AFTN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 547 AM EDT TUE MAR 19 2013
MODELS ADVERTISE PRETTY STRAIGHT FORWARD LARGE SCALE PATTERN FOR THE
LONG TERM PERIOD. AGREEMENT IN THE PRIMARY FEATURES IN THE LARGER
SCALE FLOW IS GOOD WHICH LEADS TO HIGHER CONFIDENCE FORECAST.
UPPER TROUGH FROM SOUTHERN QUEBEC/NEW ENGLAND WESTWARD ACROSS GREAT
LAKES IS MAIN FEATURE THROUGH LATE THIS WEEK. AS MOST OF UPPER JET
ENERGY ROUNDS BASE OF TROUGH...EXPECT TROUGH TO RAMBLE SLOWLY EAST
BY FRIDAY WHICH RESULTS IN HEIGHTS GRADUALLY RISING OVER UPPER GREAT
LAKES INTO NEXT WEEKEND. SFC PATTERN WELL AGREED UPON AS WELL. SFC
LOW STARTS OUT JUST EAST OF LK SUPERIOR ON WEDNESDAY THEN SHIFTS
INTO SOUTHERN QUEBEC BY THURSDAY WITH TROUGHING ENHANCED BY THE
LAKES LINGERING ACROSS LK SUPERIOR REGION. NO SIGNIFICANT CHANGE
TO PREVIOUS FCST THINKING THAT MODERATE TO AT TIMES HEAVY LK EFFECT
SNOWS IMPACT MAINLY NW SNOW BELTS OF LK SUPERIOR ON WEDNESDAY. DEEP
MOISTURE TIED TO TROUGH LINGERS AND SOUNDINGS ACTUALLY SHOW COLDEST
925-850MB TEMPS THROUGH WEDNESDAY. SFC-H95 CONVERGENCE PEGS HIGHER
TERRAIN OF WESTERN CWA ROUGHLY IRONWOOD-WAKEFIELD THROUGH TWIN LAKES
AND ATLANTIC MINE THOUGH STRONG BLYR WINDS OVER 30 KTS WILL PUSH
HEAVIER SNOW SHOWERS FARTHER INLAND THAN NORMALLY OCCURS WITH SIMILAR
WIND DIRECTION.
CONVERGENCE ALSO STRONG OVER EAST...ROUGHLY MUNISING TO NORTH OF
NEWBERRY. AGAIN STRONG WINDS MAY PUSH AT LEAST MODERATE SNOW SHOWERS
AS FAR SOUTH AS US-2 IN SCHOOLCRAFT COUNTY. HIGHEST SNOW AMOUNTS /UP
TO 6 INCHES IN 12 HRS/ EXPECTED ON WEDNESDAY. SHORTWAVE TROUGH DROPS
THROUGH THE OVERALL MEAN TROUGHING ON WEDNESDAY NIGHT. MODELS HAVE
BEEN SHOWING THIS AWHILE NOW. MAIN RESULT WILL BE WINDS SHIFTING TO
MORE NNW-N DIRECTION VERSUS NW WINDS SEEN THROUGH WEDNESDAY. SNOW
OVER NORTHWEST-WEST MARQUETTE COUNTY COULD AFFECT MORE OF THE COUNTY
WITH MORE NORTHERLY WINDS. SOUNDINGS DO INDICATE DECENT DRYING IN
WAKE OF THE WAVE IN H8-H7 LAYER BY LATER THURSDAY MORNING...BUT MOST
OF LAKE EFFECT CONVECTIVE LAYER IS WITHIN DGZ...SO SLR/S AROUND 20:1
WILL BOOST AMOUNTS. POSSIBLE THAT ADVY LEVEL SNOW AMOUNTS COULD
OCCUR LATER WEDNESDAY EVENING THROUGH MID MORNING THURSDAY OVER
MARQUETTE COUNTY...IMPACTING THU MORNING COMMUTE. LATER SHIFTS MAY
NEED TO CONSIDER HEADLINES FOR MARQUETTE COUNTY FOR THIS POTENTIAL.
DRYING SUBSIDENCE BEGINS TO TAKE BITE INTO LK EFFECT OVER WESTERN
CWA ON THURSDAY AFTN. LOCAL WRF PREFERRED WITH LOOK OF LK EFFECT
POPS/QPF THROUGH THURSDAY MORNING AND THIS INDICATES INVERSIONS
LOWERING TO LESS THAN 4KFT BY THURSDAY AFTN IN THE WEST. CURRENT
ENDING TIME OF 12Z THURSDAY FOR THE WEST LOOKING GOOD. SETUP A BIT
BETTER IN EAST THROUGH THURSDAY...BUT EVEN THERE...INVERSIONS LOWER
BLO 5KFT THOUGH THERE IS LINGERING MOISTURE BLO H7 INTO THURSDAY
EVENING. OVERALL...STRONG SUBSIDENCE/DRYING ABOVE INVERSION AND LACK
OF REAL COLD TEMPS WITHIN LK EFFECT MOIST LAYER POINTS TO
SIGNIFICANT DIMINISHING TREND TO LK EFFECT BY LATE THURSDAY
AFTN/EVENING.
EVEN SO...IT IS NOT UNTIL FRIDAY AND MAYBE EVEN AS LATE AS SATURDAY
BEFORE LOW-LEVEL FLOW OVER AREA BECOMES MORE ANTICYCLONIC AS HIGH
PRESSURE OVER NORTHERN CANADA EXPANDS INTO MANITOBA AND NORTHWEST
ONTARIO. NORTH WINDS OFF LK SUPERIOR AND TEMPS AROUND -8C KEEP
CLOUDS AND PERHAPS LGT FLURRIES GOING ON FRIDAY OVR NCNTRL UPR
MICHIGAN. AT SOME POINT...LK EFFECT WILL CEASE DUE TO INCREASING
LOW-LEVEL SHEAR AND SUBSIDENCE WITH CONTINUED WARMING TEMPS AT TOP
OF INVERSION. BY LATER IN THE WEEKEND LAST COUPLE RUNS OF GFS ARE
DEVELOPING WOUND UP SHORTWAVE/LOW PRESSURE SYSTEM IN THE CENTRAL
PLAINS. 12Z/18 MARCH ECMWF WAS MUCH MORE SUPPRESSED WITH SUCH A
SYSTEM RIDING IT ACROSS SOUTHERN TIER OF CONUS. 00Z ECMWF DID SHOW
MORE AMPLIFICATION BUT STILL KEEPS SYSTEM OVER SOUTHERN PORTION OF
OHIO VALLEY. GEM-NH/UKMET MORE WOUND UP NOW TOO...BUT LIKE ECMWF ARE
NOT NEAR AS NORTHWEST AS GFS. CAN NOT COMPLETELY COUNT OUT SOME SORT
OF SYSTEM AS TROUGHING IS PRESENT IN LARGE SCALE FROM WESTERN CANADA
INTO SOUTHERN PLAINS. PREFER THE LOOK OF WPC HAND DRAWN PROGS WITH
LOW TRACKING ACROSS SOUTHEAST CONUS AT THIS POINT. MAIN RESULT IS
QUIET WEATHER OVER UPR LAKES THROUGH THE UPCOMING WEEKEND WITH MORE
CLOUDS THAN SUNSHINE AND HIGH TEMPERATURES AT OR SLIGHTLY BLO NORMAL
IN THE LOW-MID 30S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 138 AM EDT TUE MAR 19 2013
AS THE LOW PRES TROUGH LIFTS TO THE NORTHEAST OF UPPER MI...SNOW
SHOULD DIMINISH FOR A WHILE OVERNIGHT AND MAY ALLOW CONDITIONS TO
IMPROVE TO MVFR...ESPECIALLY AT IWD AND SAW. LATE IN THE NIGHT...
STRONG WNW WINDS AND COLD AIR MOVING IN BEHIND THE LOW WILL BRING
MDT/HVY LAKE ENHANCED SNOW TO IWD/CMX WITH CONDITIONS LIKELY FALLING
TO LIFR. HOWEVER...THE WNW FLOW WILL FAVOR MAINLY MVFR CONDITIONS AT
SAW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 547 AM EDT TUE MAR 19 2013
AS LOW PRES OVER ERN LAKE SUPERIOR DRIFTS E TODAY AND TONIGHT...NW
GALES WHICH ARE CURRENTLY DEVELOPING OVER WRN LAKE SUPERIOR WILL
EXPAND E ACROSS THE LAKE TODAY. THE GALES WILL THEN CONTINUE INTO
WED OVER THE E HALF OF THE LAKE WHILE WINDS DIMINISH SLIGHTLY BELOW
GALES OVER THE W. WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO
E WED NIGHT/THU. THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES
WILL LEAD TO PERIODS OF HVY FREEZING SPRAY THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER STORM WARNING FROM 11 AM THIS MORNING TO 8 AM EDT
THURSDAY FOR MIZ006-007-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 2 PM THIS AFTERNOON TO 8 PM
EDT WEDNESDAY FOR LSZ243>245-248>251-264>267.
GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ WEDNESDAY FOR LSZ162-263-
264-266-267.
GALE WARNING FROM 2 PM THIS AFTERNOON TO 2 PM EDT WEDNESDAY FOR
LSZ243>245-249>251-265.
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY
FOR LSZ162-240>242-263.
GALE WARNING FROM 2 PM THIS AFTERNOON TO 6 AM EDT WEDNESDAY FOR
LSZ248.
GALE WARNING FROM 2 PM THIS AFTERNOON TO 11 PM EDT THIS EVENING
FOR LSZ246-247.
GALE WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
LSZ240>242.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
140 AM EDT TUE MAR 19 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 429 PM EDT MON MAR 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW NEG-TILT TROUGH/VIGOROUS
SHORTWAVE OVER ERN IA/SW WI POISED TO LIFT ENE INTO THE GREAT LAKES
AREA TONIGHT. AREA OF SNOW ASSOC WITH THIS FEATURE STRETCHES FROM
WRN LAKE SUPERIOR/SW UPR MI INTO WI AND NRN LAKE MI. FRONTAL
BOUNDARY OVER THE OHIO/TENNESSEE VALLEYS HAS EFFECTIVELY ROBBED THE
BETTER SURGE OF GULF MOISTURE N TO THE UPPER LAKES AHEAD OF WAVE.
PER 12Z RAOBS...PRECIPITABLE WATER VALUES UPWARDS OF 1 INCH ARE
SOUTH OF THE BOUNDARY WHILE VALUES ARE ONE-QUARTER TO ONE-HALF INCH
OVER THE NRN PLAINS...JUST A LITTLE ABOVE NORMAL FOR THIS TIME OF
YEAR. THE ROBBING OF MOISTURE BY THIS SRN WAVE/FRONT WILL WORK TO
KEEP SNOW ACCUMULATIONS IN CHECK DESPITE VIGOROUS DYNAMICS
ASSOCIATED WITH INCREASINGLY NEG-TILT UPR MS VALLEY SHORTWAVE.
MODEL CONSENSUS PCPN AMOUNTS INTO THIS EVENING ARE ROUGHLY 0.2 TO
0.25 INCHES. WITH SNOW RATIOS LIKELY AROUND 15 TO 1...ADVY FOR
GENERAL SNOWFALL OF 3 TO 4 INCHES STILL LOOKS ON TRACK AS THE SNOW
MAY FALL AT HEAVY AT TIMES FOR A WHILE INTO THE EVENING HRS.
SYNOPTIC SNOW WILL DIMINISH TO PATCHY -SN W TO E TONIGHT AS AREA OF
SNOW TIED TO STRONG FORCING AHEAD OF SHORTWAVE DEPARTS. ATTENTION
LATE TONIGHT THEN TURNS TO THE WRN COUNTIES WHERE STRONG NW WINDS
WILL DEVELOP IN THE WAKE OF SFC LOW MOVING ACROSS ERN LAKE SUPERIOR.
THE STRONG NW WINDS WILL ARRIVE OVER GOGEBIC/ONTONAGON COUNTIES
BEFORE REACHING THE KEWEENAW TUE MORNING. DEEP MOISTURE/CONVERGENT
CYCLONIC WNW FLOW...THE ADVECTION OF INCREASINGLY COLDER 8H TEMPS
ACROSS WRN LAKE SUPERIOR AND A DEEP DGZ SUGGEST VERY HVY LAKE
ENHANCED SNOW WILL LIKELY DEVELOP FROM KIWD N THRU THE KEWEENAW BY
DAYBREAK. COULD EASILY SEE SNOWFALL RATES OF 1-3IN/HR INTO TUESDAY
ACROSS THE HIGHER TERRAIN OF THE W. BLSN WILL ALSO BECOME AN
INCREASING HAZARD AS NW WINDS WILL GUST OVER 30MPH TO AS HIGH AS
40MPH...ESPECIALLY IN OPEN AREAS NEAR LAKE SUPERIOR. WHITE-OUTS WILL
BE A GOOD POSSIBILITY DUE TO COMBINATION OF HVY SNOW/BLSN INTO TUESDAY.
ERN COUNTIES WILL NOT GET INTO THE LAKE ENHANCED SNOW UNTIL WINDS
SHIFT FROM WEST TO NORTHWEST BEHIND COLD FROPA. AS 8H TEMPS SLOWLY
FALL TO AROUND -12 TO -13C OVER ERN LAKE SUPERIOR BY 00Z
WED...EXPECT LAKE ENHANCED SNOW TO GET GOING OVER ERN ALGER...NRN
SCHOOLCRAFT AND LUCE COUNTIES IN CYCLONIC WNW FLOW. ALTHOUGH BEST
MODEL OMEGA INITIALLY MAY STAY BLO DGZ RESULTING IN LOWER SNOW WATER
RATIOS...BELIEVE SNOW ACCUMS WILL INCREASE LATER IN THE DAY ON TUE
AND ESPECIALLY LATE TUE NIGHT AND WED AS COLDER 8H TEMPS CONTINUES TO
SEEP ACROSS ERN LAKE SUPERIOR AND LOW-LVL CONVERGENCE INCREASES WITH
FLOW VEERING NW. NW WINDS INCREASING TO 25-30 MPH...ESPECIALLY ALONG
THE LAKE SUPERIOR SHORE WILL ALSO ADD TO BLOWING SNOW AND LOWER
VSBYS TUE AFTERNOON INTO WEDNESDAY.
AS A RESULT OF CONDITIONS BECOMING INCREASINGLY MORE FAVORABLE FOR
ENHANCED SNOW AND BLOWING SNOW TUE AFTERNOON THROUGH WED
NIGHT...HAVE DECIDED TO UPGRADE WINTER STORM WATCH TO WINTER STORM
WARNING FOR ALGER...LUCE AND NRN SCHOOLCRAFT COUNTIES FOR LATE TUE
MORNING THROUGH WED NIGHT.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 429 PM EDT MON MAR 18 2013
ACTIVE LAKE EFFECT PERIOD FOR NORTHWESTERLY SNOW BELTS WILL CONTINUE
TUESDAY NIGHT INTO EARLY THURSDAY. AS UPPER LOW CLOSES OFF JUST EAST
OF THE AREA AND CYCLONIC FLOW COMBINES WITH H85 TEMPS IN THE -16 TO
-18 RANGE MODERATE TO HEAVY LAKE EFFECT SNOWS WILL CONTINUE. WINDS
WILL CONTINUE TO GUST OVER 35 MPH ESPECIALLY NEAR THE LAKESHORE
THROUGH THE DAY WEDNESDAY INTO WEDNESDAY NIGHT. WILL MAINTAIN THE
LONG DURATION WINTER STORM WARNING ACROSS THE WEST AND KEWEENAW
THROUGH THE DAY WEDNESDAY AND THE EAST INTO THURSDAY MORNING. LAKE
EFFECT SNOW TOTALS IN THE 12 TO 18 INCH RANGE SEEM LIKELY THROUGH
THE TUESDAY TO THURSDAY PERIOD.
LOW LEVEL WINDS BEGIN TO BECOME MORE NORTHERLY ON THURSDAY AS LAKE
EFFECT CONDITIONS BEGIN TO BECOME LESS FAVORABLE. AS MILDER AIR
WRAPS AROUND THE SLOWLY RETROGRADING UPPER LOW EXPECT 85H TEMPS TO
WARM INTO THE -8 TO -10 RANGE AS INVERSION LOWERS. THIS SHOULD
EFFECTIVELY END THE LAKE EFFECT BY LATE THURSDAY INTO EARLY FRIDAY.
OVERALL TREND INTO THE UPCOMING WEEKEND SHOULD FAVOR GENERALLY
TRANQUIL WEATHER WITH TEMPERATURES WITHIN A FEW DEGREES OF NORMAL.
MODELS OFFER SOME MINOR VARIATIONS WITH UPPER LOW DEPARTING THE
AREA AND UPPER PATTERN TRANSITIONING TO A MORE ZONAL FLOW WITH THE
MAIN STORM TRACK SOUTH OF THE AREA...FOR NOW WILL MAINTAIN A
CONSENSUS BLEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 138 AM EDT TUE MAR 19 2013
AS THE LOW PRES TROUGH LIFTS TO THE NORTHEAST OF UPPER MI...SNOW
SHOULD DIMINISH FOR A WHILE OVERNIGHT AND MAY ALLOW CONDITIONS TO
IMPROVE TO MVFR...ESPECIALLY AT IWD AND SAW. LATE IN THE NIGHT...
STRONG WNW WINDS AND COLD AIR MOVING IN BEHIND THE LOW WILL BRING
MDT/HVY LAKE ENHANCED SNOW TO IWD/CMX WITH CONDITIONS LIKELY FALLING
TO LIFR. HOWEVER...THE WNW FLOW WILL FAVOR MAINLY MVFR CONDITIONS AT
SAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 PM EDT MON MAR 18 2013
TIGHT PRES GRADIENT AHEAD OF THE LOW OVER NW MN WILL CONTINUE SE WINDS
UP TO 30KT TODAY. GALES WILL LIKELY OCCUR TOWARD MID LAKE PORTIONS
OF NCNTRL AND ERN LAKE SUPERIOR...IN PARTICULAR FROM AROUND
WHITEFISH PT NW TOWARD PASSAGE ISLAND. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE TONIGHT/TUE. THE
GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE. WINDS
WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU. THE
COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO PERIODS
OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER WEATHER ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR
MIZ006-007-014-085.
WINTER STORM WARNING FROM 11 AM THIS MORNING TO 8 AM EDT
THURSDAY FOR MIZ006-007-085.
WINTER WEATHER ADVISORY UNTIL 2 AM EDT /1 AM CDT/ EARLY THIS
MORNING FOR MIZ005-010>013.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 2 PM THIS AFTERNOON TO 8 PM
EDT THURSDAY FOR LSZ243>245-248>251-264>267.
GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR LSZ264-266-267.
GALE WARNING FROM 2 PM THIS AFTERNOON TO 2 PM EDT WEDNESDAY FOR
LSZ243>251-265.
HEAVY FREEZING SPRAY WARNING FROM 5 AM EDT /4 AM CDT/ EARLY THIS
MORNING TO 8 AM EDT /7 AM CDT/ THURSDAY FOR LSZ162-240>242-
263.
GALE WARNING FROM 8 AM EDT /7 AM CDT/ THIS MORNING TO 2 PM EDT
/1 PM CDT/ WEDNESDAY FOR LSZ162-240>242-263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...MZ
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
127 AM EDT TUE MAR 19 2013
.SYNOPSIS...
ISSUED AT 352 PM EDT MON MAR 18 2013
AN EXTENDED PERIOD OF LATE SEASON WINTER WEATHER WILL IMPACT
NORTHERN MICHIGAN TONIGHT THROUGH THURSDAY...AS SEVERAL ROUNDS OF
BOTH SYSTEM AND LAKE EFFECT SNOW WORK THROUGH THE REGION. THE FIRST
ROUND OF SNOW WILL CONTINUE INTO TONIGHT...AS LOW PRESSURE TRACKS
THROUGH THE UPPER MIDWEST. AS THAT SYSTEM DEPARTS INTO
ONTARIO...ANOTHER SHOT OF MUCH COLDER AIR WILL ARRIVE LATE TONIGHT
THROUGH THURSDAY...SETTING OFF SEVERAL ROUNDS OF ACCUMULATING LAKE
EFFECT SNOW. SNOW WILL FINALLY END TOWARD FRIDAY AS HIGH PRESSURE
APPROACHES...THOUGH COLD TEMPERATURES WILL REMAIN IN PLACE THROUGH
NEXT WEEKEND.
&&
.UPDATE...
ISSUED AT 1205 AM EDT TUE MAR 19 2013
FORECAST UNFOLDING ABOUT AS EXPECTED...WITH MAIN SYNOPTIC SNOW
SHIELD LIFTING THROUGH NORTHEAST LOWER/EASTERN UPPER AT THIS HOUR.
PRONOUNCED MID LEVEL DRY SLOT IS CURRENTLY OVERTAKING MUCH OF
NORTHEAST LOWER AND WILL CONTINUE TO OVERSPREAD THE ENTIRE CWA THE
NEXT FEW HOURS. LOSS OF MID LEVEL MOISTURE IS NOT HAVING MUCH OF A
BIG IMPACT ON PRECIP...HOWEVER...AS LIGHT SNOW CONTINUES FOR ALL
AREAS...WITH INFLUX OF COLDER AIR ALREADY RUSHING BACK INTO
NORTHWEST LOWER HELPING SET OFF A LAKE ENHANCEMENT RESPONSE. WAS A
LITTLE WORRIED ABOUT FREEZING DRIZZLE EARLIER...ESPECIALLY BENEATH
THE MID LEVEL DRY SLOT...AND WITHIN A WEAK GRADIENT/TROUGH REGION
LIFTING THROUGH THE CWA...BUT HAVE SEEN NO REPORTS AS SUCH TO OUR
SOUTH. THIS IS LIKELY DUE TO THE FACT THAT QUICK SURGE OF COLD
ADVECTION IS MORE THAN SUFFICIENT TO PROVIDE ICE IN THE SATURATED
LAYER...WITH LATEST RAP SOUNDINGS SUGGESTING CLOUD TOP TEMPS IN
THE -13C RANGE. AS SUCH...HAVE REMOVED ANY MENTION THE REMAINDER
OF THE NIGHT.
EXPECT SYNOPTIC SNOW SHIELD WILL LIFT PRIMARILY NORTH OF THE CWA
BY 07Z OR SO...BUT WILL BE REPLACED BY EXPANDING LAKE RESPONSE...
ESPECIALLY FOR NORTHWEST LOWER/EASTERN UPPER. SHOULD BE ABLE TO
GET RID OF HIGHER POPS FOR NORTHEAST LOWER WITH THIS AREA BETTER
REMOVED FROM THE LAKES...BUT STRENGTHENING SHEAR PROFILES SHOULD
ULTIMATELY PROVE SUFFICIENT TO KICK A FEW BANDS OF SNOW BACK INTO
EVEN THOSE AREAS WITH TIME. TEMPS A LITTLE CONVOLUTED WITH ONGOING
LOW LEVEL WARM ADVECTION CONTINUING INTO THE STRAITS/EASTERN U.P.
WHILE COLDER AIR WILL RUSH BACK INTO SOUTHWEST COUNTIES.
UPDATE ISSUED AT 920 PM EDT MON MAR 18 2013
ELONGATED SURFACE LOW CENTER STRETCHES FROM THE ARROWHEAD OF
MINNESOTA THRU WRN UPR MICHIGAN INTO LOWER MICHIGAN LATE THIS
EVENING. WIDESPREAD SNOW IS DIMINISHING TO MORE OF A PATCHY LIGHT
SNOW/FREEZING DRIZZLE REGIME ACROSS OUR SW CWA AS DEEP MOISTURE
PIVOTS NORTHWARD AHEAD OF THE SURFACE LOW CENTER. STILL EXPECT
POPS WILL REMAIN HIGH AS WE HEAD INTO THE OVERNIGHT HOURS DESPITE
A TEMPORARY DIMINISH IN INTENSITY. PATCHY LIGHT SNOW/FREEZING
DRIZZLE WILL RAMP BACK UP TO WIDESPREAD LAKE ENHANCED SNOW SHOWERS
AS COLD AIR WRAPS BACK INTO OUR CWA AS THE SURFACE LOW TRACKS THRU
THE STRAITS AND BEGINS TO DEPART INTO ONTARIO. OVERALL...EXPECT
THE NRN HALF OF OUR CWA AND NW LWR MICHIGAN WILL SEE 2 TO 4 INCHES
OF NEW SNOW THRU THE NIGHT AND 1 TO 2 INCHES FOR OUR SE CWA. WILL
CERTAINLY MAINTAIN THE WINTER WX ADVISORY FOR ERN UPR AND NW LWR
MICHIGAN WERE HIGHEST POPS AND ACCUMULATIONS WILL OCCUR.
UPDATE ISSUED AT 715 PM EDT MON MAR 18 2013
WIDESPREAD SYNOPTICALLY-DRIVEN SNOW CONTINUES TO LIFT NORTHWARD
THRU NRN MICHIGAN THIS EVENING AHEAD OF A POTENT LOW PRESSURE
SYSTEM CENTERED FROM THE ARROWHEAD OF MINNESOTA INTO NRN
WISCONSIN. MANY LOCATIONS ACROSS OUR CWA HAVE PERIODICALLY DROPPED
TO 1/2 MILE IN MODERATE SNOWFALL THIS EVENING. BACK EDGE OF THIS
PRECIP SHIELD HAS REACHED SRN LAKE MICHIGAN AND WILL GRADUALLY
LIFT NORTHWARD TOWARD OUR CWA THROUGHOUT THE EVENING. EXPECT
PRECIP INTENSITY WILL DIMINISH TO LIGHT SNOW/PATCHY FREEZING
DRIZZLE LATER THIS EVENING AS DEPTH OF MOISTURE TEMPORARILY
DIMINISHES AS THE SURFACE LOW SLIDES THRU UPPER MICHIGAN AND THE
STRAITS. SNOW SHOWERS WILL RAMP BACK UP OVERNIGHT AS CAA BEHIND
THE SURFACE LOW ACTIVATES THE LAKES AND WINDS SHIFT AROUND TO THE
WEST. FAR NRN AND NW LWR MICHIGAN WILL BE TARGETED FOR HIGHEST
POPS OVERNIGHT. IN THE MEANTIME...THE HIGHEST SNOW AMOUNTS SHOULD
BE ACROSS ERN UPR MICHIGAN AND THE TIP OF THE MIT THIS EVENING
WHERE SYNOPTIC SNOW WILL FALL FOR THE LONGEST DURATION ALONG AND
JUST NORTH OF THE LOW CENTER. EXPECT 2 TO 4 INCHES OF NEW SNOW FOR
THIS AREA THRU THE NIGHT...TAPERING TO UNDER AN INCH FOR OUR SE
COUNTIES.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 352 PM EDT MON MAR 18 2013
UPSTREAM SHORT WAVE TROUGH GOING NEGATIVE TILT WITH THE VORTICITY CENTER
NOW PRESSING INTO ILLINOIS. MAIN BATCH OF PRECIP AHEAD OF THE WAVE HAS
BEEN RAMPING UP NICELY ACROSS WISCONSIN INTO LAKE MICHIGAN AND JUST
SKIRTING UP THE NW LOWER MICHIGAN SHORELINE AREAS. PRECIP THINS
OUT CONSIDERABLY EASTWARD ACROSS LOWER MICHIGAN...BUT HAS BEEN
FILLING IN TO SOME DEGREE WITH THE APPROACH OF THE UPSTREAM WAVE
AS IT LIFTS NORTHWARD INTO NRN LOWER MICHIGAN.
TONIGHT...SHORT WAVE TROUGH/VORTICITY CENTER AND ASSOCIATED PRECIP
WILL CONTINUE TO SWING UP INTO NRN MICHIGAN OVER THE NEXT SEVERAL
HOURS. PER RADAR TRENDS...HIGHEST QPF/SNOWFALL LOOKING TO SKIRT UP
THROUGH NW LOWER MICHIGAN INTO EASTERN UPPER MICHIGAN WITH 2 TO 3
INCHES OF ACCUMULATION. LESSER AMOUNTS HEADING EASTWARD ACROSS THE
CWA. PRECIP WILL START TO TAIL OFF SOUTH-NORTH AFTER 03Z OR SO AS
WE LOSE THE FORCING...AND MAY END WITH SOME FZDZ/SNOW MIX AS THE
MID LEVELS DRY OUT A BIT.
OVERNIGHT THROUGH TUESDAY...INITIAL BATCH OF PRECIP LIFTS NORTH
WITH RESPECTABLE COLD ADVECTION SETTING UP OVERNIGHT THROUGH
TUESDAY (CORE OF COLDEST AIR SLIDES THROUGH SRN LOWER MICHIGAN).
VERY GOOD LAKE EFFECT CONDITIONS DEVELOP OVERNIGHT AND PERSIST
THROUGH TUESDAY WITHIN A WSW-WESTERLY FLOW REGIME. THIS WILL LEAD
TO WIDESPREAD LAKE EFFECT SNOW SHOWERS OVER MOST OF NW LOWER
MICHIGAN AND PARTS OF EASTERN UPPER MICHIGAN...ALONG WITH GUSTY
WINDS AND BLOWING SNOW. ONGOING ADVISORY ALREADY IN PLACE TO
ADDRESS THE HAZARD AND PLAN NO CHANGES AT THIS POINT.
&&
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 352 PM EDT MON MAR 18 2013
A PROLONGED STRETCH OF LAKE EFFECT SNOW FOR NORTHERN MICHIGAN...WITH
LITTLE SIGN OF SPRING /DESPITE WHAT THE CALENDAR SAYS/. MAIN
FORECAST ISSUES ARE SNOWFALL TOTALS AND HEADLINE MANAGEMENT.
TUESDAY NIGHT THROUGH THURSDAY...GROWING CONFIDENCE IN AN IMPRESSIVE
LATE SEASON LAKE EFFECT SNOW EVENT FOR PORTIONS OF NORTHERN
MICHIGAN. UPPER LOW WILL CLOSE OFF OVER THE NORTHERN LAKES AND
REMAIN IN THIS AREA THRU THURSDAY. A SERIES OF SFC TROFS/SHORTWAVES
WITH DEEPER POCKETS OF MOISTURE WILL ROTATE AROUND THE UPPER
LOW...ENHANCING THE SNOWFALL FROM TIME TO TIME. LOW LEVEL FLOW
FAIRLY STEADY IN THE WNW/NW RANGE THROUGHOUT...WITH EXCELLENT
CYCLONIC CURVATURE RESULTING IN A LAKE SUPERIOR CONNECTION.
FORECAST SOUNDINGS ALSO IMPRESSIVE...WITH DEEP MOISTURE AND OMEGA
THRU THE DGZ AND NEAR NON-EXISTENT INVERSIONS. LESS BULK SHEAR
PRESENT WEDNESDAY/THURSDAY AFTERNOONS...WHICH WILL SUPPORT MORE
DIURNAL DISRUPTION OF BANDING STRUCTURES BUT ALSO WILL LIKELY LEAD
TO MORE "SPREAD OUT" SNOW SHOWER ACTIVITY OUTSIDE OF THE PREFERRED LES
AREAS. ALL IN ALL...CURRENT FORECAST HAS THIS HANDLED WELL WITH AN
EXTENDED PERIOD OF CATEGORICAL POPS IN W/NW FLOW AREAS BUT AN
EXPANSION OF LIKELY POPS FOR THE AFTN HOURS WITH AFOREMENTIONED
DIURNAL DISRUPTION. PLENTY OF MESOSCALE DETAILS THAT WILL HAVE TO
BE WORKED OUT WITH REGARD TO THIS EVENT...AND THOSE ARE PROBABLY
BEST HANDLED IN THE SHORT TERM.
SO HOW MUCH SNOW WILL FALL? CIPS ANALOGS AND SIMILAR SOUNDINGS
WOULD POINT TOWARD SOME BEEFY TOTALS IN EXCESS OF A FOOT IN SOME
AREAS THRU THURSDAY. MY MAIN CONCERN IS HOW THE HIGH MARCH SUN
ANGLE MAY REALLY CUT DOWN SNOW ACCUM/S DURING THE DAYLIGHT HOURS
WITH JUST WET ROADS...WITH MOST OF THE ACCUM/S OCCURRING AT NIGHT
INTO THE EARLY MORNING HOURS. I WILL MAKE A FEW ADJUSTMENTS IN THE
CURRENT FORECAST TO TREND IT IN THIS DIRECTION WHICH WILL LIKELY
BRING DOWN STORM TOTAL SNOWFALL AMOUNTS JUST A BIT. OVERALL...
CURRENT IDEA OF A PROLONGED WINTER WEATHER ADVISORY FOR LES FAVORED
AREAS LOOKS GOOD. COULD CERTAINLY DEBATE THE TYPE OF HEADLINE /LAKE
EFFECT SNOW VERSUS WINTER WEATHER/...BUT GIVEN THE GUSTY WINDS ON
THE FRONT END OF THE EVENT AT 25 MPH...MORE GENERIC WINTER WEATHER
ADVISORY APPEARS WARRANTED. WILL ALSO LIKELY SEE SOME TIME FRAMES
OVER THIS SEVERAL DAY PERIOD WHERE HEADLINES MAY NOT BE NEEDED...BUT
TO AVOID LOTS OF HEADLINE CHANGES FROM DAY TO DAY...SIMPLER LONG
DURATION SINGLE HEADLINE LIKELY CREATES THE LEAST CONFUSION.
THURSDAY NIGHT THROUGH SUNDAY...FLOW TURNS MORE NNW THURSDAY NIGHT
WITH AIR MASS MODIFICATION WARMING WRAPPING AROUND NRN PERIPHERY OF
THE UPPER LOW THAT GRADUALLY RELEASES TO THE NE CONUS. WE REMAIN IN
BROAD TROUGHING WITH WEAK WAVES ROTATING THROUGH THE GREAT
LAKES...WITH NO REALLY GOOD CHANCE FOR SNOW. IT/S A RATHER DINGY
LOOKING AIR MASS WITH SOME AFTERNOON CUMULUS AND POSSIBLY SOME
OVERNIGHT LAKE STRATUS/FLURRIES?? WILL KEEP FORECAST PRECIP FREE FOR
NOW...WITH STRONGER MARCH SUN BRINGING TEMPERATURES BACK INTO THE
30S /WHICH IS STILL A FEW DEGREES BELOW NORMAL/.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 127 AM EDT TUE MAR 19 2013
INCREASINGLY GUSTY WEST WINDS AND PERIODS OF SNOW WILL BE THE MAIN
STORY FOR THE TERMINAL SITES THE NEXT 24 HOURS...ALL AS COLDER AIR
POURS INTO THE AREA. THE PLN/TVC AND TO A SOMEWHAT LESSER DEGREE
MBL TERMINALS WILL BE IMPACTED BY THE MOST PERSISTENT ACTIVITY...
WITH CONDITIONS SLIDING FROM MVFR EARLY THIS MORNING TOWARD IFR
THROUGH THE DAY AS LAKE EFFECT SNOW INCREASES IN INTENSITY. HAVE
SHOWN STEADY STATE IFR VISIBILITIES IN THE TAF FORECAST FOR THE
DAYLIGHT HOURS...BUT WILL NO DOUBT SEE SOME FLUCTUATIONS...WITH
PERIODS OF LIFR POSSIBLE IN HEAVIER SNOW SHOWERS. THAT SNOW WILL
WIND DOWN IN INTENSITY AND COVERAGE THROUGH THE EVENING HOURS...
BUT WITH MVFR VISBYS AND/OR CEILINGS PREVAILING. WINDS WILL BE
QUITE GUSTY AT ALL SITES THROUGH THE PERIOD FROM THE WEST/
SOUTHWEST INITIALLY...BECOMING WEST/NORTHWEST WITH TIME. GUSTS
UP TO 30 KNOTS ARE EXPECTED.
&&
.MARINE...
ISSUED AT 1205 AM EDT TUE MAR 19 2013
UPDATE: HAVE RE-ISSUED SMALL CRAFT ADVISORIES FOR ALL WATERS
(MINUS THOSE NEAR MANISTEE HARBOR WHERE GALES ARE IN EFFECT LATER
TONIGHT). EASTERLY FLOW INTO THE STRAITS/WHITEFISH BAY WILL
SLACKEN OVER THE NEXT FEW HOURS...WITH STRONGER WESTERLY WINDS
DEVELOPING FOR ALL AREAS NO LATER THAN SUNRISE. THOSE WINDS WILL
REMAIN GUSTY RIGHT ON THROUGH TONIGHT...AND WILL LIKELY HAVE TO
EVENTUALLY EXTEND THE NEWLY ISSUED HEADLINES.
PREVIOUS DISCUSSION:
GUSTY EAST TO SOUTHEAST WINDS WILL BE FOUND ACROSS ALL THE
NEARSHORE WATERS THROUGH THE EARLY EVENING HOURS...AS LOW PRESSURE
TRACKS THROUGH THE UPPER MIDWEST. SMALL CRAFT ADVISORIES WILL
CONTINUE ACROSS A GOOD CHUNK OF THE WATERS...BUT CHANNELING OF
EASTERLY FLOW WILL REQUIRE GALE WARNINGS FOR NORTHERN LAKE
HURON/LAKE MICHIGAN AND THE STRAITS...AS WELL AS WHITEFISH BAY.
WINDS WILL TEND TO DIMINISH FOR A TIME FROM SOUTH TO NORTH AS A
FRONTAL BOUNDARY LIFTS THROUGH THIS EVENING. HOWEVER...THAT LULL
WILL BE SHORT LIVED AS ANOTHER ROUND OF MUCH COLDER AIR RUSHES
BACK ACROSS THE WATERS LATER TONIGHT. SHOULD SEE AT LEAST
WIDESPREAD SMALL CRAFT ADVISORY CONDITIONS RE- DEVELOP FOR ALL
WATERS INTO TUESDAY...WITH GALE GUSTS ACROSS MAINLY SOUTHERN LAKE
MICHIGAN IMPACTING THE WATERS CLOSER TO MANISTEE. COLD CONDITIONS
AND GUSTY WINDS WILL THEN PREVAIL RIGHT ON THROUGH WEDNESDAY
NIGHT...WITH ADDITIONAL SMALL CRAFT ADVISORIES EXPECTED.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 8 PM EDT THURSDAY FOR MIZ008-
019>022-026>028.
WINTER WEATHER ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR MIZ015>017-
025-031-032.
LH...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LHZ345-347>349.
LM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LMZ323-341-342-
344.
GALE WARNING UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ345-346.
LS...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LSZ321.
&&
$$
UPDATE...LAWRENCE
SYNOPSIS...NS
SHORT TERM...BA
LONG TERM...JK
AVIATION...LAWRENCE
MARINE...BA/LAWRENCE
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1205 AM EDT TUE MAR 19 2013
.SYNOPSIS...
ISSUED AT 352 PM EDT MON MAR 18 2013
AN EXTENDED PERIOD OF LATE SEASON WINTER WEATHER WILL IMPACT
NORTHERN MICHIGAN TONIGHT THROUGH THURSDAY...AS SEVERAL ROUNDS OF
BOTH SYSTEM AND LAKE EFFECT SNOW WORK THROUGH THE REGION. THE FIRST
ROUND OF SNOW WILL CONTINUE INTO TONIGHT...AS LOW PRESSURE TRACKS
THROUGH THE UPPER MIDWEST. AS THAT SYSTEM DEPARTS INTO
ONTARIO...ANOTHER SHOT OF MUCH COLDER AIR WILL ARRIVE LATE TONIGHT
THROUGH THURSDAY...SETTING OFF SEVERAL ROUNDS OF ACCUMULATING LAKE
EFFECT SNOW. SNOW WILL FINALLY END TOWARD FRIDAY AS HIGH PRESSURE
APPROACHES...THOUGH COLD TEMPERATURES WILL REMAIN IN PLACE THROUGH
NEXT WEEKEND.
&&
.UPDATE...
ISSUED AT 1205 AM EDT TUE MAR 19 2013
FORECAST UNFOLDING ABOUT AS EXPECTED...WITH MAIN SYNOPTIC SNOW
SHIELD LIFTING THROUGH NORTHEAST LOWER/EASTERN UPPER AT THIS HOUR.
PRONOUNCED MID LEVEL DRY SLOT IS CURRENTLY OVERTAKING MUCH OF
NORTHEAST LOWER AND WILL CONTINUE TO OVERSPREAD THE ENTIRE CWA THE
NEXT FEW HOURS. LOSS OF MID LEVEL MOISTURE IS NOT HAVING MUCH OF A
BIG IMPACT ON PRECIP...HOWEVER...AS LIGHT SNOW CONTINUES FOR ALL
AREAS...WITH INFLUX OF COLDER AIR ALREADY RUSHING BACK INTO
NORTHWEST LOWER HELPING SET OFF A LAKE ENHANCEMENT RESPONSE. WAS A
LITTLE WORRIED ABOUT FREEZING DRIZZLE EARLIER...ESPECIALLY BENEATH
THE MID LEVEL DRY SLOT...AND WITHIN A WEAK GRADIENT/TROUGH REGION
LIFTING THROUGH THE CWA...BUT HAVE SEEN NO REPORTS AS SUCH TO OUR
SOUTH. THIS IS LIKELY DUE TO THE FACT THAT QUICK SURGE OF COLD
ADVECTION IS MORE THAN SUFFICIENT TO PROVIDE ICE IN THE SATURATED
LAYER...WITH LATEST RAP SOUNDINGS SUGGESTING CLOUD TOP TEMPS IN
THE -13C RANGE. AS SUCH...HAVE REMOVED ANY MENTION THE REMAINDER
OF THE NIGHT.
EXPECT SYNOPTIC SNOW SHIELD WILL LIFT PRIMARILY NORTH OF THE CWA
BY 07Z OR SO...BUT WILL BE REPLACED BY EXPANDING LAKE RESPONSE...
ESPECIALLY FOR NORTHWEST LOWER/EASTERN UPPER. SHOULD BE ABLE TO
GET RID OF HIGHER POPS FOR NORTHEAST LOWER WITH THIS AREA BETTER
REMOVED FROM THE LAKES...BUT STRENGTHENING SHEAR PROFILES SHOULD
ULTIMATELY PROVE SUFFICIENT TO KICK A FEW BANDS OF SNOW BACK INTO
EVEN THOSE AREAS WITH TIME. TEMPS A LITTLE CONVOLUTED WITH ONGOING
LOW LEVEL WARM ADVECTION CONTINUING INTO THE STRAITS/EASTERN U.P.
WHILE COLDER AIR WILL RUSH BACK INTO SOUTHWEST COUNTIES.
UPDATE ISSUED AT 920 PM EDT MON MAR 18 2013
ELONGATED SURFACE LOW CENTER STRETCHES FROM THE ARROWHEAD OF
MINNESOTA THRU WRN UPR MICHIGAN INTO LOWER MICHIGAN LATE THIS
EVENING. WIDESPREAD SNOW IS DIMINISHING TO MORE OF A PATCHY LIGHT
SNOW/FREEZING DRIZZLE REGIME ACROSS OUR SW CWA AS DEEP MOISTURE
PIVOTS NORTHWARD AHEAD OF THE SURFACE LOW CENTER. STILL EXPECT
POPS WILL REMAIN HIGH AS WE HEAD INTO THE OVERNIGHT HOURS DESPITE
A TEMPORARY DIMINISH IN INTENSITY. PATCHY LIGHT SNOW/FREEZING
DRIZZLE WILL RAMP BACK UP TO WIDESPREAD LAKE ENHANCED SNOW SHOWERS
AS COLD AIR WRAPS BACK INTO OUR CWA AS THE SURFACE LOW TRACKS THRU
THE STRAITS AND BEGINS TO DEPART INTO ONTARIO. OVERALL...EXPECT
THE NRN HALF OF OUR CWA AND NW LWR MICHIGAN WILL SEE 2 TO 4 INCHES
OF NEW SNOW THRU THE NIGHT AND 1 TO 2 INCHES FOR OUR SE CWA. WILL
CERTAINLY MAINTAIN THE WINTER WX ADVISORY FOR ERN UPR AND NW LWR
MICHIGAN WERE HIGHEST POPS AND ACCUMULATIONS WILL OCCUR.
UPDATE ISSUED AT 715 PM EDT MON MAR 18 2013
WIDESPREAD SYNOPTICALLY-DRIVEN SNOW CONTINUES TO LIFT NORTHWARD
THRU NRN MICHIGAN THIS EVENING AHEAD OF A POTENT LOW PRESSURE
SYSTEM CENTERED FROM THE ARROWHEAD OF MINNESOTA INTO NRN
WISCONSIN. MANY LOCATIONS ACROSS OUR CWA HAVE PERIODICALLY DROPPED
TO 1/2 MILE IN MODERATE SNOWFALL THIS EVENING. BACK EDGE OF THIS
PRECIP SHIELD HAS REACHED SRN LAKE MICHIGAN AND WILL GRADUALLY
LIFT NORTHWARD TOWARD OUR CWA THROUGHOUT THE EVENING. EXPECT
PRECIP INTENSITY WILL DIMINISH TO LIGHT SNOW/PATCHY FREEZING
DRIZZLE LATER THIS EVENING AS DEPTH OF MOISTURE TEMPORARILY
DIMINISHES AS THE SURFACE LOW SLIDES THRU UPPER MICHIGAN AND THE
STRAITS. SNOW SHOWERS WILL RAMP BACK UP OVERNIGHT AS CAA BEHIND
THE SURFACE LOW ACTIVATES THE LAKES AND WINDS SHIFT AROUND TO THE
WEST. FAR NRN AND NW LWR MICHIGAN WILL BE TARGETED FOR HIGHEST
POPS OVERNIGHT. IN THE MEANTIME...THE HIGHEST SNOW AMOUNTS SHOULD
BE ACROSS ERN UPR MICHIGAN AND THE TIP OF THE MIT THIS EVENING
WHERE SYNOPTIC SNOW WILL FALL FOR THE LONGEST DURATION ALONG AND
JUST NORTH OF THE LOW CENTER. EXPECT 2 TO 4 INCHES OF NEW SNOW FOR
THIS AREA THRU THE NIGHT...TAPERING TO UNDER AN INCH FOR OUR SE
COUNTIES.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 352 PM EDT MON MAR 18 2013
UPSTREAM SHORT WAVE TROUGH GOING NEGATIVE TILT WITH THE VORTICITY CENTER
NOW PRESSING INTO ILLINOIS. MAIN BATCH OF PRECIP AHEAD OF THE WAVE HAS
BEEN RAMPING UP NICELY ACROSS WISCONSIN INTO LAKE MICHIGAN AND JUST
SKIRTING UP THE NW LOWER MICHIGAN SHORELINE AREAS. PRECIP THINS
OUT CONSIDERABLY EASTWARD ACROSS LOWER MICHIGAN...BUT HAS BEEN
FILLING IN TO SOME DEGREE WITH THE APPROACH OF THE UPSTREAM WAVE
AS IT LIFTS NORTHWARD INTO NRN LOWER MICHIGAN.
TONIGHT...SHORT WAVE TROUGH/VORTICITY CENTER AND ASSOCIATED PRECIP
WILL CONTINUE TO SWING UP INTO NRN MICHIGAN OVER THE NEXT SEVERAL
HOURS. PER RADAR TRENDS...HIGHEST QPF/SNOWFALL LOOKING TO SKIRT UP
THROUGH NW LOWER MICHIGAN INTO EASTERN UPPER MICHIGAN WITH 2 TO 3
INCHES OF ACCUMULATION. LESSER AMOUNTS HEADING EASTWARD ACROSS THE
CWA. PRECIP WILL START TO TAIL OFF SOUTH-NORTH AFTER 03Z OR SO AS
WE LOSE THE FORCING...AND MAY END WITH SOME FZDZ/SNOW MIX AS THE
MID LEVELS DRY OUT A BIT.
OVERNIGHT THROUGH TUESDAY...INITIAL BATCH OF PRECIP LIFTS NORTH
WITH RESPECTABLE COLD ADVECTION SETTING UP OVERNIGHT THROUGH
TUESDAY (CORE OF COLDEST AIR SLIDES THROUGH SRN LOWER MICHIGAN).
VERY GOOD LAKE EFFECT CONDITIONS DEVELOP OVERNIGHT AND PERSIST
THROUGH TUESDAY WITHIN A WSW-WESTERLY FLOW REGIME. THIS WILL LEAD
TO WIDESPREAD LAKE EFFECT SNOW SHOWERS OVER MOST OF NW LOWER
MICHIGAN AND PARTS OF EASTERN UPPER MICHIGAN...ALONG WITH GUSTY
WINDS AND BLOWING SNOW. ONGOING ADVISORY ALREADY IN PLACE TO
ADDRESS THE HAZARD AND PLAN NO CHANGES AT THIS POINT.
&&
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 352 PM EDT MON MAR 18 2013
A PROLONGED STRETCH OF LAKE EFFECT SNOW FOR NORTHERN MICHIGAN...WITH
LITTLE SIGN OF SPRING /DESPITE WHAT THE CALENDAR SAYS/. MAIN
FORECAST ISSUES ARE SNOWFALL TOTALS AND HEADLINE MANAGEMENT.
TUESDAY NIGHT THROUGH THURSDAY...GROWING CONFIDENCE IN AN IMPRESSIVE
LATE SEASON LAKE EFFECT SNOW EVENT FOR PORTIONS OF NORTHERN
MICHIGAN. UPPER LOW WILL CLOSE OFF OVER THE NORTHERN LAKES AND
REMAIN IN THIS AREA THRU THURSDAY. A SERIES OF SFC TROFS/SHORTWAVES
WITH DEEPER POCKETS OF MOISTURE WILL ROTATE AROUND THE UPPER
LOW...ENHANCING THE SNOWFALL FROM TIME TO TIME. LOW LEVEL FLOW
FAIRLY STEADY IN THE WNW/NW RANGE THROUGHOUT...WITH EXCELLENT
CYCLONIC CURVATURE RESULTING IN A LAKE SUPERIOR CONNECTION.
FORECAST SOUNDINGS ALSO IMPRESSIVE...WITH DEEP MOISTURE AND OMEGA
THRU THE DGZ AND NEAR NON-EXISTENT INVERSIONS. LESS BULK SHEAR
PRESENT WEDNESDAY/THURSDAY AFTERNOONS...WHICH WILL SUPPORT MORE
DIURNAL DISRUPTION OF BANDING STRUCTURES BUT ALSO WILL LIKELY LEAD
TO MORE "SPREAD OUT" SNOW SHOWER ACTIVITY OUTSIDE OF THE PREFERRED LES
AREAS. ALL IN ALL...CURRENT FORECAST HAS THIS HANDLED WELL WITH AN
EXTENDED PERIOD OF CATEGORICAL POPS IN W/NW FLOW AREAS BUT AN
EXPANSION OF LIKELY POPS FOR THE AFTN HOURS WITH AFOREMENTIONED
DIURNAL DISRUPTION. PLENTY OF MESOSCALE DETAILS THAT WILL HAVE TO
BE WORKED OUT WITH REGARD TO THIS EVENT...AND THOSE ARE PROBABLY
BEST HANDLED IN THE SHORT TERM.
SO HOW MUCH SNOW WILL FALL? CIPS ANALOGS AND SIMILAR SOUNDINGS
WOULD POINT TOWARD SOME BEEFY TOTALS IN EXCESS OF A FOOT IN SOME
AREAS THRU THURSDAY. MY MAIN CONCERN IS HOW THE HIGH MARCH SUN
ANGLE MAY REALLY CUT DOWN SNOW ACCUM/S DURING THE DAYLIGHT HOURS
WITH JUST WET ROADS...WITH MOST OF THE ACCUM/S OCCURRING AT NIGHT
INTO THE EARLY MORNING HOURS. I WILL MAKE A FEW ADJUSTMENTS IN THE
CURRENT FORECAST TO TREND IT IN THIS DIRECTION WHICH WILL LIKELY
BRING DOWN STORM TOTAL SNOWFALL AMOUNTS JUST A BIT. OVERALL...
CURRENT IDEA OF A PROLONGED WINTER WEATHER ADVISORY FOR LES FAVORED
AREAS LOOKS GOOD. COULD CERTAINLY DEBATE THE TYPE OF HEADLINE /LAKE
EFFECT SNOW VERSUS WINTER WEATHER/...BUT GIVEN THE GUSTY WINDS ON
THE FRONT END OF THE EVENT AT 25 MPH...MORE GENERIC WINTER WEATHER
ADVISORY APPEARS WARRANTED. WILL ALSO LIKELY SEE SOME TIME FRAMES
OVER THIS SEVERAL DAY PERIOD WHERE HEADLINES MAY NOT BE NEEDED...BUT
TO AVOID LOTS OF HEADLINE CHANGES FROM DAY TO DAY...SIMPLER LONG
DURATION SINGLE HEADLINE LIKELY CREATES THE LEAST CONFUSION.
THURSDAY NIGHT THROUGH SUNDAY...FLOW TURNS MORE NNW THURSDAY NIGHT
WITH AIR MASS MODIFICATION WARMING WRAPPING AROUND NRN PERIPHERY OF
THE UPPER LOW THAT GRADUALLY RELEASES TO THE NE CONUS. WE REMAIN IN
BROAD TROUGHING WITH WEAK WAVES ROTATING THROUGH THE GREAT
LAKES...WITH NO REALLY GOOD CHANCE FOR SNOW. IT/S A RATHER DINGY
LOOKING AIR MASS WITH SOME AFTERNOON CUMULUS AND POSSIBLY SOME
OVERNIGHT LAKE STRATUS/FLURRIES?? WILL KEEP FORECAST PRECIP FREE FOR
NOW...WITH STRONGER MARCH SUN BRINGING TEMPERATURES BACK INTO THE
30S /WHICH IS STILL A FEW DEGREES BELOW NORMAL/.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 715 PM EDT MON MAR 18 2013
WIDESPREAD SYNOPTICALLY-DRIVEN SNOW CONTINUES TO LIFT NORTHWARD
THRU ALL OF NRN LWR MICHIGAN THIS EVENING...DROPPING VSBYS TO IFR
IN MANY LOCATIONS. SNOWFALL INTENSITY/RATES WILL DIMINISH FROM
SOUTH TO NORTH THIS EVENING AS THE LOW CENTER ARRIVES ACROSS NRN
SECTIONS OF OUR CWA AND THE INITIAL AREA OF DEEP MOISTURE LIFTS
NORTH INTO THE UPPER PENINSULA. ADDITIONAL DEEP MOISTURE WILL
SWEEP BACK INTO NRN LWR MICHIGAN OVERNIGHT...IGNITING LAKE EFFECT
SNOW SHOWERS AND CAA KICKS IN ON THE BACKSIDE OF THE SURFACE LOW.
THUS...IFR/WIDESPREAD SNOW WILL TEMPORARILY TRANSITION TO
MVFR/LIGHT SNOW/PATCHY FREEZING DRIZZLE...AND THEN CHANGE BACK TO
IFR/WIDESPREAD SNOW FOR MUCH OF FAR NRN AND NW LWR MICHIGAN
(PLN/TVC/MBL) OVERNIGHT AS LAKE EFFECT SNOW DEVELOPS. GUSTY E/SE
WINDS WILL DIMINISH AS THE LOW CENTER MOVES OVERHEAD THIS
EVENING...SHIFT TO THE WEST AND STRENGTHEN AGAIN BY DAYBREAK...
WITH GUSTS TO 30 KTS EXPECTED.
&&
.MARINE...
ISSUED AT 1205 AM EDT TUE MAR 19 2013
UPDATE: HAVE RE-ISSUED SMALL CRAFT ADVISORIES FOR ALL WATERS
(MINUS THOSE NEAR MANISTEE HARBOR WHERE GALES ARE IN EFFECT LATER
TONIGHT). EASTERLY FLOW INTO THE STRAITS/WHITEFISH BAY WILL
SLACKEN OVER THE NEXT FEW HOURS...WITH STRONGER WESTERLY WINDS
DEVELOPING FOR ALL AREAS NO LATER THAN SUNRISE. THOSE WINDS WILL
REMAIN GUSTY RIGHT ON THROUGH TONIGHT...AND WILL LIKELY HAVE TO
EVENTUALLY EXTEND THE NEWLY ISSUED HEADLINES.
PREVIOUS DISCUSSION:
GUSTY EAST TO SOUTHEAST WINDS WILL BE FOUND ACROSS ALL THE
NEARSHORE WATERS THROUGH THE EARLY EVENING HOURS...AS LOW PRESSURE
TRACKS THROUGH THE UPPER MIDWEST. SMALL CRAFT ADVISORIES WILL
CONTINUE ACROSS A GOOD CHUNK OF THE WATERS...BUT CHANNELING OF
EASTERLY FLOW WILL REQUIRE GALE WARNINGS FOR NORTHERN LAKE
HURON/LAKE MICHIGAN AND THE STRAITS...AS WELL AS WHITEFISH BAY.
WINDS WILL TEND TO DIMINISH FOR A TIME FROM SOUTH TO NORTH AS A
FRONTAL BOUNDARY LIFTS THROUGH THIS EVENING. HOWEVER...THAT LULL
WILL BE SHORT LIVED AS ANOTHER ROUND OF MUCH COLDER AIR RUSHES
BACK ACROSS THE WATERS LATER TONIGHT. SHOULD SEE AT LEAST
WIDESPREAD SMALL CRAFT ADVISORY CONDITIONS RE- DEVELOP FOR ALL
WATERS INTO TUESDAY...WITH GALE GUSTS ACROSS MAINLY SOUTHERN LAKE
MICHIGAN IMPACTING THE WATERS CLOSER TO MANISTEE. COLD CONDITIONS
AND GUSTY WINDS WILL THEN PREVAIL RIGHT ON THROUGH WEDNESDAY
NIGHT...WITH ADDITIONAL SMALL CRAFT ADVISORIES EXPECTED.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 8 PM EDT THURSDAY FOR MIZ008-
019>022-026>028.
WINTER WEATHER ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR MIZ015>017-
025-031-032.
LH...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LHZ345-347>349.
LM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LMZ323-341-342-
344.
GALE WARNING UNTIL 5 PM EDT TUESDAY FOR LMZ345-346.
LS...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LSZ321.
&&
$$
UPDATE...LAWRENCE
SYNOPSIS...NS
SHORT TERM...BA
LONG TERM...JK
AVIATION...MR
MARINE...BA/LAWRENCE
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
419 AM CDT TUE MAR 19 2013
.DISCUSSION...
WHERE THE BAND OF PRECIPITATION (SNOW/RAIN-SNOW/SPRINKLES) WILL
SET UP TODAY AND THE POTENTIAL FOR ACCUMULATING SNOW
THURSDAY/THURSDAY NIGHT ARE THE PRIMARY FORECAST CHALLENGES.
AT H5...THERE ARE A COUPLE AREAS OF INTEREST. THE FIRST AREA IS A
SERIES OF SHORTWAVES EMBEDDED IN THE NORTHWEST FLOW FROM IDAHO AND
MONTANA INTO COLORADO. THE SECOND ARE SHORTWAVES EMBEDDED IN THE
FLOW FROM CALIFORNIA INTO NEVADA. THERE IS A STRONG 130KT JET THAT
IS CO-LOCATED FROM IDAHO INTO WESTERN NEBRASKA AND A 10KT JET
NOSING INTO CALIFORNIA. OTHERWISE...THE STORM SYSTEM THAT BROUGHT A
RAIN SNOW MIX TO THE REGION OVER THE WEEKEND IS STILL PRODUCING SNOW
FOR THE UPPER GREAT LAKES.
EARLY THIS MORNING...IR SATELLITE IMAGERY SHOWS ENHANCED CLOUDS FROM
MONTANA SOUTHEAST TO NEBRASKA. MID CLOUDS HAVE THICKENED OVER
NEBRASKA AND ECHOES ARE SHOWING UP ON RADAR...MOSTLY ALOFT AS
SURFACE REPORTS ARE DRY SAVE FOR LEXINGTON. THE NORTHERN JET
DIVES INTO THE PLAINS WHILE CALIFORNIA JET HEADS INTO
ARIZONA...PROVIDING SOME UPPER LEVEL DIVERGENCE FROM SOUTHERN
NEBRASKA INTO KANSAS. AS THE SHORTWAVE TROF MOVES ACROSS
NEBRASKA...H7-H3 OMEGA AND LAPSE RATES AND H85-7 FRONTOGENESIS
INCREASE OVER PARTS OF NEBRASKA THIS MORNING AND QUICKLY SHIFTS
INTO KANSAS AND MISSOURI THIS AFTERNOON. THE SHORT RANGE MODELS
VARY ON THE EXACT LOCATION OF THE FRONTOGENETIC BAND. THE RAP/NAM
ARE MAINLY SOUTHWEST OF A LINE FROM DAVID CITY TO FALLS
CITY......WHILE THE GFS IS SOUTHWEST OF BEATRICE...THE 4KM WRF IS
IN BETWEEN THE TWO...AND THE THE 21Z SREF IS FARTHER NORTHEAST.
THE RAP WAS MOSTLY NOT AVAILABLE. DO INCLUDE SOME CHANCE POPS
SOUTHEAST OF A LINE FROM DAVID CITY TO LINCOLN TO FALLS CITY...FOR
LIGHT SNOW THEN RAIN MIXED WITH SNOW THIS MORNING AND LIGHT RAIN
THIS AFTERNOON. INCLUDED CHANCE FOR SPRINKLES FARTHER NORTH THIS
AFTERNOON AND IN SOUTHWEST IOWA EARLY THIS EVENING.
THERE IS SOME FRONTOGENESIS TONIGHT AND WARM AIR ADVECTION AHEAD
OF THE NEXT EMBEDDED SHORT WAVED AND REINFORCING COLD AIR FOR
WEDNESDAY. FOR NOW...JUST INCLUDED A FEW CLOUDS OVERNIGHT. HIGH
WEDNESDAY WILL MOSTLY BE IN THE 30S...WITH A FEW LOWER 40S WITH
BREEZY NORTHWEST WINDS IN THE MORNING.
WEDNESDAY NIGHT...UPSLOPE FLOW DEVELOPS OVER THE WESTERN
PLAINS...AHEAD OF A STORM SYSTEM THAT IS APPROACHING FROM THE
PACIFIC NORTHWEST. H85 FLOW INCREASES AND DEEPER MOISTURE BEGINS
TO MOVE NORTHWARD ACROSS TEXAS.
THE MODELS ARE SIMILAR THURSDAY AND THURSDAY NIGHT IN DEVELOPING
AN ELONGED AREA OF LOW PRESSURE FROM EASTERN WYOMING SOUTH INTO
TEXAS. THE SOUTHERN PART OF THE LOW AREA IS STRONGER AND ORGANIZED
PRECIPITATION DEVELOP ACROSS OKLAHOMA...KANSAS...MISSOURI AND
ARKANSAS. THE MODELS DIFFER ON WHERE THE H85 LOW WILL TRACK WITH
THE SOUTHERN SYSTEM AND THE STRENGTH OF THE NORTHERN PLAINS WAVE
INFLUENCE. THERE IS THE POTENTIAL FOR A BAND OF LIGHT SNOW WITH
THESE FEATURES ACROSS THE CWA. FOR NOW HAVE CHANCE POPS IN THE
WEST AND SOUTH WHERE DYNAMICS APPEARS STRONGEST. HOPE TO HAVE A
BETTER SENSE AS TO HOW THIS SYSTEM WILL EVOLVE AFTER IT MOVES
ONSHORE WITH BETTER SAMPLING WEDNESDAY. HIGHS THURSDAY ARE IN THE
30S.
FOR THE EXTENDED...FRIDAY AND FRIDAY NIGHT...WE WILL STILL BE
UNDER THE INFLUENCE OF THE PACIFIC NORTHWEST CLOSED H5 LOW
PRESSURE SYSTEM. BY SATURDAY MORNING...THE AREA OF H5 LOW PRESSURE
REMAINS OVER MONTANA THRU UTAH AND COLORADO...BUT HAS CUT OF ON
AREA OVER UT/CO AND THIS DROPS SOUTH DURING THE DAY. THERE COULD
BE SOME LIGHT SNOW. WITH LOW CONFIDENCE HAVE KEPT POPS LOW. THE H5
LOW TRACKS ACROSS KANSAS OR OKLAHOMA. DEPENDING ON HOW FAR NORTH
THE SYSTEM TRACKS...IT COULD BRING SNOW TO KANSAS OR MISSOURI OR
TO NEBRASKA. THE GFS IS VERY BULLISH WITH PRECIPITATION AND A
MORE NORTHERN TRACK. FOR NOW HAVE FOLLOWED THE MORE OF A SOUTHERN
TRACK OF THE EC THROUGH SUNDAY...SO WILL HAVE TO KEEP A WATCH ON
THIS. BELOW NORMAL TEMPERATURES CONTINUE THRU MONDAY.
&&
.AVIATION...
06Z TAFS FOR KOMA...KLNK...AND KOFK.
VFR CONDITIONS SHOULD PREVAIL THROUGH AT LEAST MID MORNING TUESDAY
AT KOMA AND KOFK...BUT COULD DROP TO THE MVFR CATEGORY OR LOWER AT
KLNK BETWEEN 12Z-16Z WITH SNOW OR MIXED PCPN. MID LEVEL CLOUDINESS
CONTINUED TO SPREAD EAST AND LOWER...BUT CEILINGS SHOULD REMAIN
ABOVE 5000 FEET THROUGH 12Z. HIGHEST POTENTIAL FOR MVFR CEILINGS
AT KOMA IS 15Z-19Z. KOFK COULD HAVE CEILINGS IN THE 3000-5000
FOOT RANGE 15Z-19Z...ALONG WITH A RAIN/SNOW MIX. HIGH PRESSURE
BUILDS IN FOR TUESDAY NIGHT WITH NORTH/NORTHWEST WINDS.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1145 PM CDT MON MAR 18 2013
.UPDATE...
CLOUDS ARE INCREASING A BIT FASTER THAN EXPECTED. WITH SOME WEAK
RADAR RETURNS TO THE WEST ALREADY...INTRODUCED SOME SCATTERED
FLURRIES LATE FOR PARTS OF SOUTHEAST NEBRASKA. EVENING RUNS OF
THE NAM AND RAP MODELS ALSO SHOWED MORE POTENTIAL FOR SNOW OR A
RAIN/SNOW MIX IN PARTS OF SOUTHEAST NEBRASKA TUESDAY MORNING...
SO UPDATED FOR THAT EARLIER.
MILLER
&&
.AVIATION...
06Z TAFS FOR KOMA...KLNK...AND KOFK.
VFR CONDITIONS SHOULD PREVAIL THROUGH AT LEAST MID MORNING TUESDAY
AT KOMA AND KOFK...BUT COULD DROP TO THE MVFR CATEGORY OR LOWER AT
KLNK BETWEEN 12Z-16Z WITH SNOW OR MIXED PCPN. MID LEVEL CLOUDINESS
CONTINUED TO SPREAD EAST AND LOWER...BUT CEILINGS SHOULD REMAIN
ABOVE 5000 FEET THROUGH 12Z. HIGHEST POTENTIAL FOR MVFR CEILINGS
AT KOMA IS 15Z-19Z. KOFK COULD HAVE CEILINGS IN THE 3000-5000
FOOT RANGE 15Z-19Z...ALONG WITH A RAIN/SNOW MIX. HIGH PRESSURE
BUILDS IN FOR TUESDAY NIGHT WITH NORTH/NORTHWEST WINDS.
MILLER
&&
.PREV DISCUSSION... /ISSUED 257 PM CDT MON MAR 18 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY.
WINDY CONDITIONS ACROSS THE AREA THIS AFTERNOON WITH ADVISORY
IN PLACE ACROSS MOST OF THE NORTH HALF OF THE CWA. WILL LET
ADVISORY CONTINUE UNTIL EXPIRATION AT 23Z WITH WINDS DROPPING OFF
THROUGH THE EVENING AS HIGH PRESSURE BUILDS INTO THE REGION
TONIGHT. AREA WILL BE ON THE WESTERN EDGE OF THE MAIN POOL OF
COLD AIR SPREADING INTO THE MID MISSISSIPPI VALLEY. NEXT WEAK
WAVE DROPS INTO THE NORTHERN PLAINS AND UPPER MIDWEST ON TUESDAY
ALLOWING SOME WARMER AIR TO BRIEFLY RETURN NORTH IN ADVANCE OF THE
FEATURE BEFORE THE NEXT COLD SURGE COMES IN TUESDAY NIGHT. MODELS
CONTINUE TO SUGGEST SOME POTENTIAL FOR SHOWERS ALONG LEADING EDGE
OF THE COLD AIR SO HAVE LEFT CURRENT MENTION OF FLURRIES OR
SPRINKLES AS IS FOR TUESDAY AFTERNOON.
COLD AIR LINGERS THROUGH WEDNESDAY BEFORE MID LEVEL SHORT WAVE
RIDGE MOVES IN WEDNESDAY NIGHT AHEAD OF NEXT MAJOR WAVE COMING
INTO THE NORTHERN ROCKIES. THIS SYSTEM IS SOMEWHAT FRAGMENTED
INITIALLY WITH SEVERAL SHORT WAVES INDICATED BY MODELS ACROSS THE
WESTERN CONUS BEFORE SPLITTING INTO A NORTHERN AND SOUTHERN STREAM
COMPLEX THURSDAY NIGHT INTO FRIDAY. CHANCE OF SNOW RETURNS TO
PARTS OF THE AREA ON THURSDAY AS INITIAL WAVE DIGS INTO THE
SOUTHERN PLAINS WITH SURFACE LOW ALONG THE TEXAS OKLAHOMA BORDER.
FORECAST AREA GENERALLY IN BETWEEN THESE TWO FEATURES ON THURSDAY
SO POPS ON THE LOW SIDE FOR NOW EXCEPT ALONG THE SOUTHEAST BORDER
WHERE HIGHER CHANCE POPS IN PLACE.
FOBERT
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
GFS/CMC/ECM SFC TEMP METEOGRAMS ARE IN GOOD AGREEMENT THAT THE MAIN
THEME IN THE EXTENDED PDS IS LITTLE HOPE FOR A WARMING TREND. THUS
EXPECT BELOW NORM TEMPS WILL BE THE RULE DAYS 4-7. ALL THIS IN PART
TO MEAN UPPER TROUGHING ENVELOPING THE CNTRL CONUS PER
GEFS/CMCENS/ECMENS. MEANWHILE DETERMINISTIC ECM/CMC PROGS SEEM TO
BE IN RELATIVELY DECENT AGREEMENT AFT DAY 4 WITH THE GFS THE
OUTLIER.
POSSIBLE PCPN THURS NIGHT IS INITIAL CONCERN. QPF FIELDS ARE FOR THE
MOST PART FOCUSED SOUTH/WEST OF THE CWA ALONG AXIS OF WEAK/MODERATE
AGEOSTROPHIC LIFT. UPPER SUPPORT IS INSIGNIFICANT...THUS NOT VERY
IMPRESSED WITH PCPN POTENTIAL. AT THIS POINT CANNOT TOTALLY DISCOUNT
SOME LIGHT SNOW ACTIVITY REACHING THE WRN CWA PERIPHERY.
HOWEVER...HAVE OPTED TO BUMP POPS DOWN JUST A BIT. AS A MATTER OF
FACT THOUGH...NOT IMPRESSED WITH PCPN POTENTIAL AT ALL FRIDAY AND
BEYOND. AT THIS POINT FEEL COMPELLED THEN TO DROP ALL GOING POPS TO
SLGT CAT.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
355 AM EDT TUE MAR 19 2013
.SYNOPSIS...
THE COMBINATION OF A WARM FRONT LIFTING THROUGH THE REGION...AND LOW
PRESSURE LIFTING NORTHEAST ALONG THE COAST...WILL PROVIDE MUCH OF
OUR AREA WITH WIDESPREAD MODERATE TO LOCALLY HEAVY SNOW THROUGH
TONIGHT. STEADIER SNOWS WILL TAPER OFF BY WEDNESDAY...BUT ON AND OFF
SNOW SHOWERS...CLOUDY SKIES AND SEASONABLY COOL TEMPERATURES ARE
EXPECTED TO CONTINUE THROUGH THE END OF THE WORK WEEK AS UPPER LEVEL
LOW PRESSURE REMAINS ATOP THE NORTHEAST. SOME IMPROVEMENT IS
EXPECTED BY LATER IN THE WEEKEND INTO EARLY NEXT WEEK AS CONDITIONS
TREND DRIER AND TEMPERATURES RETURN TO NEAR NORMAL LEVELS.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 355 AM EDT TUESDAY...FORECAST REMAINS MORE OR LESS ON TRACK
WE HEAD INTO TODAY AS SFC WARM FRONT CONTINUES TO MAKE SLOW
PROGRESS NORTH AND EAST INTO THE REGION. DECENT ISENTROPIC LIFT
AND AMBIENT OMEGA IN THE DENDRITIC SNOW GROWTH ZONE ALL POINT TO
CONTINUE CATEGORICAL POPS FOR LIGHT TO MODERATE SNOW THROUGH THE
DAYLIGHT HOURS THOUGH ACCUMULATIONS WILL BE A TOUGH CALL GIVEN
HIGHER MARCH SUN ANGLE AND MARGINAL TEMPERATURES AT OR SLIGHTLY
ABOVE FREEZING BY THIS AFTERNOON...ESP IN THE LOWER ELEVATIONS. MY
GUT FEELING TELLS ME MY DAYTIME ACCUMULATIONS MAY BE A BIT
OVERDONE...ESP IN THE 12-18Z TIME FRAME WHEN A LULL IN THE PCPN
MAY OCCUR DURING TIME OF MAXIMUM INSOLATION. BUT TO PLAY DEVIL`S
ADVOCATE IT MAY BE MORE OR LESS ACCURATE FOR THE 12-HR PERIOD AS
POTENTIAL HIGHER RATES WILL LIKELY RAMP UP QUICKLY BY LATE
AFTERNOON/EARLY EVENING AS DEVELOPING COASTAL LOW PRESSURE RIDES
NORTHEASTERLY TO NEAR KBOS BY 00Z. INDEED...THIS MORNING`S GFS
SOLN IS STILL FAIRLY BULLISH ON DEVELOPMENT OF A BACK-END STRONG
DEFORMATION AXIS PROGRESSING SLOWLY EASTWARD FROM THE ERN DACKS
INTO THE CPV AND POINTS EAST THIS AFTERNOON/EARLY EVENING...AND
HAS BROAD SUPPORT FROM RECENT RAP RUNS. SOUNDING PROFILES SUGGEST
VERY STRONG OMEGA AND MID-LEVEL FRONTOGENETICAL FORCING WITH THIS
FEATURE WITH POTENTIAL 1-2" PER HOUR SNOWFALL RATES WITHIN A FEW
HOURS +/- OF THE 21-00Z HOUR TIME FRAME. THE DEVELOPMENT OF THIS
FEATURE APPEARS AT LEAST IN PART DUE TO THE PARENT GREAT LAKE
OCCLUSION`S SFC FRONT AND UPPER TROUGH AXIS PROGRESSING EASTWARD
AND LEADING TO STRONG LOW TO MID LEVEL CONVERGENCE AS IT UNDERCUTS
THE DEEPER ATLANTIC MOISTURE. INDEED...THERE IS A STARK WIND SHIFT
FROM MEAN SOUTH/SOUTHEASTERLY TO WEST/SOUTHWESTERLY IN THE LOWER
TO MID LEVELS ALONG THIS BOUNDARY...AND WHILE THIS MORNING`S NAM
AND OUR LOCALLY RUN WRF MODELS DEPICT THE DEVELOPMENT OF THE HEAVY
PCPN BAND SOMEWHAT DIFFERENTLY THAN THE GFS...MY FEELING THEY BOTH
ARE CORRECT IN THE BAND DEVELOPMENT...THOUGH ARRIVING AT IT IN
DIFFERENT WAYS. SO I`LL CONTINUE WITH PRIOR FORECASTER`S IDEA THAT
MOST AREAS FROM THE DACKS EASTWARD SHOULD SEE A 2-4 HOUR PERIOD OF
MODERATE TO HEAVY SNOWFALL LATER THIS AFTERNOON THROUGH EARLY TO
MID EVENING WHICH WILL PRODUCE ADDITIONAL BACK-END AMOUNTS OF 4-8
INCHES. AS IS TYPICAL WITH TWO-PHASED AND/OR LATE SEASON EVENTS
SUCH AS THIS...THERE WILL BE WINNERS AND LOSERS IN THE SNOWFALL.
MOST PROBLEMATIC MAY END UP BEING AREAS ACROSS THE SLV WHERE
HEAVIEST TOTALS WILL LIKELY TO COME ON THE FRONT END WARM THERMAL
ADVECTION PCPN THIS MORNING...WITH THIS AREA POSSIBLY A BIT TOO
FAR TO THE WEST OF THE PRIMARY FRONTAL INTERACTION WITH THE
COASTAL LOW THIS EVENING. TIME WILL TELL.
AS WE PROGRESS INTO THE LATER EVENING AND OVERNIGHT HOURS...FRONTAL
ZONE AND BETTER MOISTURE/LOW LEVEL CONVERGENCE CONTINUE TO PUSH
EAST TAKING STEADIER AND HEAVIER SNOWS INTO EASTERN NEW ENGLAND AND
OUT OF OUR FORECAST AREA. THUS EXPECTING A GRADUAL TAPERING TO VERY
LIGHT SNOW OR SNOW SHOWERS AFTER MIDNIGHT WITH ADDITIONAL
ACCUMULATIONS ON THE MINOR SIDE AS TEMPERATURES BOTTOM OUT IN THE
LOWER TO MID 20S BY SUNRISE ON WEDNESDAY. TOTAL SNOWFALL AMOUNTS
AVERAGING 7-10" IN THE SLV...9-12" DACKS AND CPV...AND 10-15"
ACROSS ERN VT WHERE STEADIER SNOWS WILL PERSIST THE LONGEST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 355 AM EDT TUESDAY...THIS MORNING`S MODELS REMAIN IN BROAD
AGREEMENT FROM WEDNESDAY INTO THURSDAY IN OFFERING A CONTINUED
CLOUDY AND UNSETTLED WEATHER PATTERN FOR OUR REGION AS A LARGE-
SCALE UPPER CYCLONIC GYRE REMAINS ATOP THE NORTHEAST. THUS I`LL
OFFER A MORE OR LESS PERSISTENCE FORECAST THROUGH THIS TIME FRAME
WITH ON AND OFF/PERIODIC FLURRIES AND SHSN...ESPECIALLY ACROSS OUR
CENTRAL AND NORTHERN COUNTIES. WHILE HEAVY SNOW IS NOT
EXPECTED...ADDITIONAL LIGHT SNOW ACCUMULATIONS ARE LIKELY...ESP AT
NIGHT AND ACROSS THE HIGHER ELEVATIONS OF THE CENTRAL AND NORTHERN
MTNS AS TEMPERATURES CONTINUE TO RUN ON THE COOL SIDE WITH DAILY
MEANS AVERAGING 3 TO 7 DEGREES BELOW NORMAL.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 355 AM EDT TUESDAY...BROAD UPPER LOW WILL CONTINUE TO BRING
LIGHT WINTRY PRECIPITATION TO THE NORTH COUNTRY AS THE SYSTEM
SLOWLY TRUDGES EAST INTO THE CANADIAN MARITIMES...THURSDAY NIGHT
INTO THE BEGINNING OF THE UPCOMING WEEKEND. MDLS BRING HIGH
PRESSURE INTO THE AREA ON SATURDAY FROM THE WEST AS UPPER LOW
EXITS AND REMAINS INTO NEXT MONDAY. BOTH GFS/ECMWF DO HINT AT
ANOTHER COASTL LOW SHUNTED TO OUR SOUTH DO TO BLOCKING RIDGE OVER
NORTHEAST. OVERALL FOR EXPECTED -SW ACTIVITY...WILL TAPER DOWN
POPS FOR MUCH OF CWA GOING INTO SATURDAY WITH BEST CHANCES OVER
HIR TRRN/NORTHERN ZONES DO TO NW FLOW ON BACKSIDE OF SYSTEM. SOME
LIGHT ACCUM POSSIBLE OVER DACKS/NC VT. CLRING TREND/SL WARMING
TREND ENSUES OVER THE REST OF THE WEEKEND W/ SFC HIGH OVER AREA.
FULL MARCH SUNSHINE WILL BRING SLIGHTLY INCR TEMPS FOR MUCH OF
EXTENDED PERIOD TOPPING OFF WITH HIGHS AROUND 40F FOR SUNDAY AND
NEXT MONDAY...WHILE OVERNGT LOWS RANGE MAINLY IN THE TEENS/L20S.
SOME SINGLE NUMBERS POSSIBLE IN DACKS/NE KINGDOM SAT/SUN NITES
FROM CLRING SKIES/RADIATIONAL COOLING.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
THROUGH 06Z WEDNESDAY...WINTER STORM PUSHING THRU THE AREA WILL
BRING A MIX OF MVFR/IFR VSBY THRU FORECAST PERIOD RANGING MAINLY
FROM 3-5SM W/ PERIODS OF 1-2SM AT TIMES. CEILINGS WILL RANGE FROM
VFR DOWN TO MVFR W/ BKN015-040. WINDS INITIALLY ENE TO SSE
10-20KTS THRU THIS AFTNOON THEN BECM WSW 5-10KTS FOR MSS/SLK...AND
NNW 5-10KTS FOR REST OF FORECAST SITES.
OUTLOOK 06Z WEDNESDAY THROUGH SATURDAY...
06Z WEDNESDAY THROUGH 12Z WEDNESDAY...IFR OR LOWER SNOW CONTINUES
THROUGH 04-08Z AS LOW DRAWS NORTHWARD ALONG COASTAL NEW ENGLAND.
SOME BRIEFLY HEAVIER SNOW LIKELY DURING THIS TIME.
12Z WEDNESDAY THROUGH SATURDAY...MIX OF VFR/MVFR/IFR CIGS AND VSBYS
LIKELY WITH UPPER LEVEL LOW PRESSURE CONTINUING TO PROVIDE THE
REGION WITH ON AND OFF SNOW SHOWERS.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING UNTIL 8 AM EDT WEDNESDAY FOR VTZ001>012-
016>019.
NY...WINTER STORM WARNING UNTIL 8 AM EDT WEDNESDAY FOR NYZ026>031-
034-035-087.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG
SHORT TERM...JMG
LONG TERM...JN
AVIATION...JN/MUCCILLI
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1036 PM PDT Mon Mar 18 2013
.SYNOPSIS...
Active March weather will continue with cool, breezy and showery
conditions. After the showers decrease this evening, a vigorous
storm system will bring rain, snow, and windy conditions to the
Pacific Northwest Wednesday into Wednesday night. Cool and showery
conditions are expected Thursday into the upcoming weekend.
&&
.DISCUSSION...
Update: general forecast is on track save for a minor adjustments.
Winds remain locally breezy but trends and RAP guidance continues
to indicate winds abating, with the slackening gradients and
decoupling. I adjust overnight low up a 2-3 degrees where winds
remain a bit breezier, toward the basin, and up about a degree
based on newest guidance and trends. Otherwise the isolated
showers are dissipating through the Panhandle this hour and
should largely be winding down, save for perhaps around the
Panhandle mountains (closer to the MT border) where the mean
northwest flow linger.
The next system is on the approach and newest guidance continues to
the lower level flow turning easterly going into Tuesday. With
this evening`s 00Z sounding showing some drying and subsidence, it
will take time for the atmosphere to moisten up again before the
next threat of precipitation really gets going. So much of Tuesday
looks dry.
By Tuesday night into Wednesday the incoming system taps some
moisture (with precipitable water values rising to around 150% of
normal). The system appears to have a "one-two" punch. First the
leading warm front and weakening mid-level wave come in Tuesday
night into early Wednesday morning, with the first precipitation
peak. Second, after a strictly relative-lull going into mid-
morning, the more dynamic cold front and negatively- tilted upper
wave coming through on Wednesday, with precipitation rates for the
entire system peaking around Wednesday afternoon.
With some exceptions, snow levels are expected to rise to around
2500 to 5000 feet. This is supported by 850mb temperatures in the
lower to mid-single digits (Celsius) and a stout southerly flow
(850mb winds around 20-40 kts). The exceptions will be around the
Cascades through Canadian border counties, especially for Tuesday
night/early Wednesday morning. This includes the Wenatchee area
through Okanogan Valley. A southeast flow will promote cold air
damming, with 850mb temps around 0 to -3C. With this set-up and
the potential for wet-bulb cooling, snow levels here will be closer
to valley floors.
Thus some snow accumulations are possible in these areas, which
may make the Wednesday morning commute slick and slower. The
mountain areas and passes may also see some moderate accumulations.
By late morning to early afternoon snow levels here are also
expected to rise out of the valleys. Before then, however, some
highlights may be needed. /J. Cote`
&&
.AVIATION...
06Z TAFS: Upper wave exits tonight, with a brief break coming
Tuesday before a wetter system approaches Tuesday night. Primarily
VFR conditions through the period, but clouds will be on the
increase and lowering going into Tuesday afternoon and evening
(especially after 23-01Z). The primary threat of precipitation
will come after 00Z Wednesday (Tuesday evening) into the KEAT/KMWH
area, approaching the remainder of the TAF sites toward the end of
this TAF period. Local MVFR cigs are possible some of these showers.
Winds are generally expected to be 10kts or less, except around
the KPUW to KMWH area as they approaching system will increase
gradients in the afternoon. Some higher gusts are possible in
these areas by Tuesday afternoon, especially near KPUW. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 24 49 37 51 32 46 / 10 0 80 90 40 30
Coeur d`Alene 24 48 35 49 31 45 / 10 0 80 100 60 40
Pullman 26 51 37 51 32 43 / 10 10 80 90 40 40
Lewiston 31 57 39 58 36 49 / 10 10 60 80 40 30
Colville 21 51 32 50 29 48 / 10 0 80 90 40 30
Sandpoint 22 44 32 47 29 44 / 20 0 80 100 70 50
Kellogg 22 44 32 46 29 40 / 40 0 80 100 80 50
Moses Lake 25 54 36 56 33 51 / 0 10 70 60 10 10
Wenatchee 29 50 35 54 32 49 / 0 30 70 60 10 10
Omak 25 50 32 54 29 49 / 0 10 80 80 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1220 AM CDT TUE MAR 19 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...DECIDED TO EXTEND THE WINTER WEATHER ADVISORY UNTIL 10
O`CLOCK TUESDAY FOR AREA SOUTH OF HIGHWAY 29 AND ALSO FOR DOOR
COUNTY AS MODELS FORECAST 40 KNOT WINDS AT 925 MPH LATER TONIGHT
AND TUESDAY MORNING WITH STRONG COLD ADVECTION AND FRESH SNOW ON
THE GROUND. CONSIDERABLE BLOWING AND DRIFTING SNOW POSSIBLE ON
NORTH SOUTH ROADS IN RURAL AREAS. WOULD NOT BE SURPRISED TO HAVE
SOME ROADS CLOSED WHERE DRIFTS ARE USUALLY A PROBLEM. DID NOT
INCLUDE THE AREAS FURTHER NORTH AS THE GRADIENT IS WEAKER AND THAT
REGION IS MOSTLY WOODED WHICH SLOWS DOWN THE WIND.
RDM
&&
.PREV DISCUSSION...ISSUED AT 719 PM CDT MON MAR 18 2013...
SHORT TERM...
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG
SHORTWAVE MOVING ACROSS THE NORTHERN MISSISSIPPI VALLEY EARLY THIS
AFTERNOON. AHEAD OF THIS TROUGH...A SHORTWAVE IMPULSE LIFTED
NORTH OVER SOUTHEAST WISCONSIN THIS MORNING AND ACROSS NORTHEAST
WISCONSIN THIS AFTERNOON. THIS IMPULSE HAS GENERATED WIDESPREAD
1/4SM TO 1/2SM ACROSS THE FOX VALLEY AND LAKESHORE. THE MAIN BAND
OF SNOW RIGHT AHEAD OF THE MAIN SHORTWAVE IS MOVING ACROSS CENTRAL
WISCONSIN WHERE MODERATE TO HEAVY SNOW IS ALSO OCCURRING. JUST
LEARNED ABOUT HWY 13 FROM WISCONSIN RAPIDS TO THE DELLS THAT TRAVEL
BECOMING NOT ADVISED. THOUGHT ABOUT EXPANDING THE ADVISORY ACROSS
THE REST OF THE AREA...BUT WEBCAMS FROM OSHKOSH SHOW LITTLE IN THE
WAY OF ACCUMULATIONS ON THEIR ROADWAYS. ROAD TEMPERATURES ARE A
COUPLE DEGREES WARMER THERE THAN FARTHER NORTH AND WEST...WHICH
COULD EXPLAIN PART OF THE ACCUMULATION DIFFERENCES. WITH THE BACK
EDGE OF THE HEAVIER SNOW NOT TOO FAR AWAY FROM THE SOUTHERN FOX
VALLEY...WILL KEEP THEM OUT OF THE ADVISORY. ROADS ARE BECOMING
SNOW COVERED IF NOT ALREADY SNOW COVERED FARTHER NORTH...SO WILL LET
THE ADVISORY GO AS PLANNED. WILL BUMP UP ACCUMS A BIT OVER NE
WISCONSIN. THE EVENING CREW MAY BE ABLE TO CANCEL THE ADVISORY
EARLY IF THE STRENGTHENING WINDS THIS EVENING DO NOT CREATE BLOWING
AND DRIFTING SNOW OF ANY SIGNIFICANCE.
TONIGHT...SHORTWAVE TROUGH WILL SWING NE ACROSS NORTHEAST WISCONSIN
THIS EVENING...AS ITS PARENT TROUGH CLOSES OFF OVER THE UPPER
PENINSULA AND LAKE SUPERIOR. THE LATEST HRRR SUGGESTS MOST OF THE
SYNOPTIC SNOW WILL HAVE PEELED OUT BY THE START OF THE
PERIOD...EXCEPT OVER NORTH-CENTRAL WISCONSIN WHERE DEEP MOISTURE
WILL HANG IN PLACE. WHERE THE UPPER AND MID-LEVEL MOISTURE DOES
DEPART...SNOW WILL DIMINISH TO FLURRIES OR PATCHY LIGHT FREEZING
DRIZZLE. WILL KEEP FZDZ WORDING AS CHANCE SINCE OBS UPSTREAM SEEM
WIDELY SCT...BUT POTENTIAL WILL BE THERE FOR A FEW HOURS.
WRAP-AROUND SNOW THEN TO RETURN LATE IN THE EVENING AND OVERNIGHT.
PLENTY OF LOW VSBYS IN SNOW SHOWERS OVER SOUTHERN MINNESOTA AND
EASTERN SD...SO DO NOT FEEL COMFORTABLE GOING JUST FLURRIES THOUGH
ACCUMS SHOULD ONLY BE A TENTH TO A HALF INCH. MEANWHILE...ARCTIC AIR
WILL BE PUNCHING ACROSS CENTRAL AND SOUTHERN WISCONSIN DURING THE
EVENING...AND INTO NORTHEAST WISCONSIN OVERNIGHT. AS THIS COLDER
AIR ARRIVES...WEST WEST WILL BE STRENGTHENING AND BECOME QUITE
GUSTY. THE BEST PRESSURE RISES WILL SPLIT THE AREA TO THE NORTH AND
SOUTH...BUT SOME GUSTS COULD STILL REACH 35 MPH. UPSTREAM OFFICES
CANCELLED THEIR BLIZZARD WARNINGS EARLY SINCE VSBYS WERE NOT LOW
ENOUGH...SUGGESTING BLOWING AND DRIFTING MAY NOT HAVE BEEN AS BIG A
FACTOR AS PREVIOUSLY THOUGHT. EARLY INDICATIONS OF SNOWFALL RATIOS
SO FAR TODAY ARE AROUND 10-12 TO 1...SO SNOW MAY BE TOO WET TO RESTRICT
VSBYS DUE TO BLOWING. WILL KEEP THE END TIME OF THE ADVISORY AT
03Z.
MONDAY...THE UPPER LOW WILL SHIFT A LITTLE NE OVER LAKE SUPERIOR
TOMORROW...TAKING SOME OF THE DEEPER MOISTURE WITH IT. SHOULD STILL
BE ENOUGH MOISTURE AND CYCLONIC FLOW ALOFT FOR OCCASIONAL SNOW
SHOWERS AND FLURRIES DURING THE MORNING...THEN BECOMING CONFINED TO
N-C WISCONSIN DURING THE AFTERNOON. WEST TO NORTHWEST WINDS WILL
REMAIN GUSTY...AND AN ISOLATED GUST UP TO 40 MPH WILL BE POSSIBLE IN
THE OPEN AREAS. TEMPS MAINLY IN THE MIDDLE 20S.
LONG TERM...
LITTLE CHANGE IN THE OVERALL...COLD...PATTERN FOR THE REGION
THROUGH THIS PERIOD. BROAD UPPER TROF OVER EASTERN TWO THIRDS OF
U.S. UPPER LOW TO SPIN OVER EASTERN LAKES INTO FRI...WHILE
MAIN STORM TRACK AND MOISTURE REMAINS TO OUR SOUTH. AT THE SURFACE
CANADIAN HIGH PRESSURE TO REMAIN OVER THE REGION.
TUE NIGHT INTO THU...
MAIN ISSUES LAKE EFFECT CHANCES AND CHANCE FOR SNOW SHOWERS ON
WED. PIECES OF ENERGY WILL CIRCULATE AROUND THE LOW THIS
PERIOD...BRINGING THREAT OF SNOW SHOWERS...FLURRIES. BEST CHANCE
TO BE ON WED AS UPPER TROF DROPS SOUTH OVER THE STATE.
HAVE TRIED TO ADD DEFINITION TO LAKE EFFECT CHANCES...WITH HIGHEST
CHANCES LATE TUE NIGHT INTO WEDNESDAY NIGHT AS HAVE SOME SYNOPTIC
LIFT AND MOISTURE. BY THE TIME THE WINDS BECOME MORE FAVORABLE
LATER WED NIGHT AND THU...SOUNDINGS SHOW LOWERING INVERSION
HEIGHTS AND DRYING WORKING IN.
THU NIGHT ONWARD...
EXTENDED MODELS STILL HAVING ISSUES LATER PERIODS...BRINGING LIGHT
QPF INTO THE REGION. STILL EXPECT ANY PACIFIC SYSTEM TO DIVE SE
AND PASS TOO FAR TO OUR SOUTH TO BRING ORGANIZED PCPN TO NE WI.
WITH HIGH PRESSURE AT SURFACE THROUGH PERIOD AND LIMITED MOISTURE
HAVE STAYED WITH DRY FORECAST. LLVL WINDS SHIFT TO NE FOR BRIEF
PERIOD SAT...WITH THOUGHTS OF LES OFF LAKE MICHIGAN. THOUGH AGAIN MOISTURE
AND INSTABILITY LIMITED. BELOW NORMAL TEMPERATURES EXPECTED TO
CONTINUE INTO THE LAST WEEK OF MARCH. HAVE AGAIN DROPPED FEW
DEGREES OFF GUIDANCE TEMPS FOR LATTER PERIODS.
&&
.AVIATION...MAINLY MVFR CIGS AND VSBYS WITH SCATTERED SNOW SHOWERS
TO PERSIST THIS MORNING. SNOW SHOWERS AND BLOWING SNOW WITH STRONG
WEST WINDS WILL PRODUCE IFR VSBYS AT TIMES THIS MORNING WITH THE
FRESH SNOW. AS THE SYSTEM SHIFTS EAST LATER TODAY...CONDITIONS TO
IMPROVE TO VFR LEVELS ALONG WITH SOME DECREASE IN THE SUSTAINED WEST
WIND SPEED. SURFACE WIND GUSTS TO 25 MPH MAY LINGER OVER NORTHEAST
WISCONSIN THROUGH WEDNESDAY.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ022-
030-031-035>040-045-048>050-074.
WINTER WEATHER ADVISORY UNTIL 1 AM CDT EARLY THIS MORNING FOR
WIZ005-010>013-018>021-073.
&&
$$
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1050 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COASTAL LOW JUST OFF TO OUR EAST HEADS NORTHEAST TODAY AND
TONIGHT...AND INTO THE CANADIAN MARITIMES ON WEDNESDAY. ANOTHER
COASTAL LOW WILL DEVELOP OFF THE MID ATLANTIC COAST WEDNESDAY
NIGHT...AND TRACK WELL SOUTHEAST OF LONG ISLAND THURSDAY AND WELL
EAST OF CAPE COD THURSDAY NIGHT. WEAK HIGH PRESSURE WILL BUILD IN
ON FRIDAY AND REMAIN THROUGH THE WEEKEND. LOW PRESSURE WILL PASS
TO THE SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BAND OF PCPN...MOSTLY RAIN...MOVES ACROSS THE CWA LATE THIS
MORNING INTO EARLY AFTERNOON. HAVE ISSUED AN SPS FOR THE DURATION
OF THE MORNING FOR THE POTENTIAL OF ADDITIONAL LIGHT ICE
ACCUMULATION FOR THE NORTHERN FRINGE ZONES AND LET THE WINTER
STORM WARNING EXPIRE. TEMPERATURES HERE COULD STILL BE AROUND OR
JUST ABOVE FREEZING DURING THIS TIME. BASED ON OBS TO THE WEST AND
THE ANTICIPATION OF COLDER AIR MOVING IN ALOFT...SOME SNOW MAY BE
MIXED IN AS WELL WITH THIS BAND MOVING THROUGH.
FOR HIGH TEMPS...BLENDED MAV/MET WITH COLDER 04Z RAP 2M
TEMPS...WITH HIGHS ONLY NEAR 40 INLAND WHICH COULD STILL BE A
LITTLE GENEROUS ESPECIALLY ACROSS SRN CT...AND MID 40S FOR NYC
METRO AND LONG ISLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FAST W TO WSW FLOW ALOFT TONIGHT AND THURSDAY AS CLOSED LOW BUILDS
INTO NORTHERN NEW ENGLAND...THEN SE CANADA. SHOULD BE DRY TONIGHT
AND THURSDAY WITH LITTLE IF ANY IN THE WAY OF FORCING - HOWEVER IF
UPPER TROUGH AXIS IS A TAD SLOWER IN PUSHING THROUGH THAN CURRENTLY
FORECAST COULD SEE SOME -SHSN ACROSS NORTHERN ZONES EARLY THIS
EVENING. FOR LOWS TONIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. USED A BLEND OF
MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM
850 HPA NEAR THE IMMEDIATE COAST...800 HPA ACROSS FAR INTERIOR
AREAS AND 825 HPA IN BETWEEN. THIS YIELDS HIGHS AROUND 10 DEGREES
BELOW NORMAL.
A COASTAL LOW DEVELOPS OFF THE MID ATLANTIC COAST WEDNESDAY NIGHT IN
RESPONSE TO A SOUTHERN STREAM SHORTWAVE MOVING OFFSHORE - THIS LOW
THEN MOVES WELL SE OF LONG ISLAND THURSDAY AND TO THE E OF CAPE COD
THURSDAY NIGHT AS THE NORTHERN STREAM CUTOFF LOW PIVOTS TO THE SE
INTO THE TRI-STATE. THE RESULT WILL BE CHANCE POPS COASTAL
AREAS/SLIGHT CHANCE POPS ELSEWHERE FOR LIGHT SNOW FROM LATE
WEDNESDAY NIGHT INTO THURSDAY EVENING - EXCEPT OVER FAR NW ZONES
WHERE ONLY COULD SEE A FEW FLURRIES.
USED A BLEND OF MAV/MET GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH
VALUES FORECAST TO BE AROUND 5 DEGREES BELOW NORMAL. USED A BLEND
OF MIXING DOWN FROM 850 HPA NEAR THE COAST...800 HPA WELL
INLAND...AND 825 HPA IN BETWEEN...WITH A BLEND OF MAV/MET
GUIDANCE...AND NAM AND ECMWF 2-METER TEMPERATURES. THIS YIELDS
VALUES 10-15 DEGREES BELOW NORMAL. FOR LOWS THURSDAY NIGHT USED A
BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH VALUES AROUND
5 DEGREES BELOW NORMAL.
NW FLOW ALOFT FRIDAY WITH UPPER LOW OVER N AND E NEW ENGLAND - COULD
GET ENOUGH FORCING OUT OUT OF A PASSING SHORTWAVE IN THE AFTERNOON
TO WARRANT SLIGHT CHANCE POPS FOR -SHSN/-SHRA OVER FAR NW ZONES. FOR
HIGHS USED A BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH
VALUES AROUND 10 DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS BEGINNING TO COME INTO BETTER AGREEMENT WITH THE HANDLING
AND TIMING OF HIGH PRESSURE SYSTEM OVER THE COMING WEEKEND...AND
THE NEXT LOW PRESSURE SYSTEM FOR NEXT MONDAY/TUESDAY.
HIGH PRESSURE BUILDS TO THE SOUTH OVER THE NORTHEAST SATURDAY INTO
SUNDAY UNDER A BROAD UPPER LEVEL TROUGH. MULTIPLE SHORTWAVES
EXPECTED TO PASS THROUGH THE REGION WHILE ROTATING AROUND THE MAIN
UPPER LEVEL CLOSED LOW. DESPITE DECENT FORCING ASSOCIATED WITH EACH
PASSING WAVE...A PERSISTENT NORTHWESTERLY FLOW WILL KEEP A MAINLY
DRY VERTICAL COLUMN...RESULTING IN DRY CONDITIONS ACROSS THE AREA.
WHILE THE 12Z/18 RUNS HAD MUCH HIGHER DISCREPANCIES IN THE HANDLING
OF THE NEXT LOW...THE 00Z/19 RUNS ARE STARTING TO COME INTO BETTER
ALIGNMENT BUT STILL WITH SOME DIFFERENCES. LOW PRESSURE FORMS OVER
THE CENTRAL STATES ON SUNDAY...PROGRESSING TO THE EAST TO BEGIN
THE WEEK. 00Z ECMWF ACTUALLY THE MORE PROGRESSIVE OF THE SOLUTIONS...
WITH THE GFS LAGGING BEHIND WHILE DEVELOPING A SECONDARY LOW. THE
GFS THEN KEEPS THE UPPER LEVEL LOW FROM OVER THE WEEKEND NEARLY
STATIONARY...ALLOWING FOR POSSIBLE INTERACTION WITH THE NEXT LOW
TRAVERSING THE CENTRAL US...RESULTING IN MORE WIDESPREAD
PRECIPITATION. HOWEVER...THE PATTERN OF THE ECMWF KEEPS THE
TRAVERSING LOW TO THE SOUTH...BUILDING IN SUBSIDENCE OVER MOST OF
THE NORTHEAST...KEEPING THE HEAVIEST PRECIPITATION TO THE SOUTH.
BECAUSE OF THE MODEL SPREAD...CONTINUED THE SLIGHT CHANCE POPS FOR
MONDAY INTO TUESDAY.
GENERALLY USED A BLEND OF THE WPC AND MOS GUIDANCE FOR TEMPS THIS
WEEKEND INTO NEXT WEEK...WHICH KEEPS HIGH TEMPS SLIGHTLY BELOW
NORMAL AND OVERNIGHT LOWS RIGHT AROUND TO SLIGHTLY BELOW NORMAL.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE IS SOUTH OF LONG ISLAND THIS MORNING. THIS LOW WILL
WILL MOVE NORTHEAST INTO COASTAL NEW ENGLAND THIS EVENING.
WINDS ARE FROM THE NORTHEAST WITH IFR CIGS. AN AREA OF SHOWERS AND
LIGHT DRIZZLE WILL MOVE THROUGH THE TERMINALS THROUGH THE LATER
MORNING AND EARLY AFTERNOON HOURS. BY AFTERNOON...AS THE LOW MOVES
NORTHEAST...WINDS WILL BECOME MORE WESTERLY AND GUST TO 20-30KT.
IFR CIGS WILL ALSO RAPIDLY INCREASE TO VFR.
WESTERLY WINDS CONTINUE OVERNIGHT WITH SPEEDS DIMINISHING AND
GUSTS ENDING. VFR CONDITIONS OVERNIGHT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: WIND SHIFT TO NORTHWEST AND IFR CIGS
IMPROVING TO VFR COULD BE OFF BY AN HOUR OR TWO. VFR CIGS EXPECTED
BY 19Z. AMENDMENTS POSSIBLE.
KLGA FCSTER COMMENTS: WIND SHIFT TO NORTHWEST AND IFR CIGS
IMPROVING TO VFR COULD BE OFF BY AN HOUR OR TWO. VFR CIGS EXPECTED
BY 19Z. AMENDMENTS POSSIBLE.
KEWR FCSTER COMMENTS: WIND SHIFT TO NORTHWEST AND IFR CIGS
IMPROVING TO VFR COULD BE OFF BY AN HOUR OR TWO. VFR CIGS EXPECTED
BY 19Z. AMENDMENTS POSSIBLE.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: WIND SHIFT TO NORTHWEST AND IFR CIGS
IMPROVING TO VFR COULD BE OFF BY AN HOUR OR TWO. VFR CIGS EXPECTED
BY 19Z. AMENDMENTS POSSIBLE.
KHPN FCSTER COMMENTS: WIND SHIFT TO NORTHWEST AND IFR CIGS
IMPROVING TO VFR COULD BE OFF BY AN HOUR OR TWO. VFR CIGS EXPECTED
BETWEEN 19Z-20Z. AMENDMENTS POSSIBLE.
KISP FCSTER COMMENTS: WIND SHIFT TO NORTHWEST AND IFR CIGS
IMPROVING TO VFR COULD BE OFF BY AN HOUR OR TWO. VFR CIGS EXPECTED
BETWEEN 20Z-21Z. AMENDMENTS POSSIBLE.
.OUTLOOK FOR 12Z WED THROUGH SAT...
.WED...GENERALLY VFR. W WINDS WITH GUSTS INTO THE LOWER 20 KT
RANGE ON WED.
.THU...CHANCE OF SUB-VFR IN LIGHT SNOW.
.FRI...VFR. GUSTY NW WINDS POSSIBLE.
.SAT...VFR.
&&
.MARINE...
MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE.
OCCASIONAL GUSTS UP TO 35 KT WILL BE POSSIBLE ACROSS THE EASTERN
WATERS FOR THE DURATION OF THE MORNING AS THE PRESSURE GRADIENT
WILL BE RELATIVELY TIGHTER HERE DUE TO THE PROXIMITY OF A LOW
PRESSURE CENTER JUST OFF TO THE SOUTH OF MONTAUK. OTHERWISE...SCA
CONDITIONS EXPECTED ACROSS THE AREA TODAY.
WINDS INCREASE TONIGHT AS COASTAL LOW DEEPENS TO THE EAST - SO
HAVE ISSUED A GALE WARNING FOR ALL WATERS FOR TONIGHT. GALE GUSTS
CONTINUE ON WEDNESDAY OVER EASTERN COASTAL OCEAN WATERS -
ANZ350-353 - WITH SMALL CRAFT CONDITIONS ELSEWHERE. THE PRESSURE
GRADIENT RELAXES OVER THE REGION WEDNESDAY NIGHT...WITH ALL WATERS
FALLING BELOW SCA LEVELS AFTER MIDNIGHT..AND CONTINUE ON THURSDAY.
WIND GUSTS ON THE COASTAL OCEAN WATERS COULD REACH 25 KT THURSDAY
NIGHT IN THE WAKE OF THE DEPARTING...BUT STRENGTHENING COASTAL
LOW...WITH SUB-SMALL CRAFT CONDITIONS ON THE REMAINDER OF THE WATERS.
FRIDAY WILL FEATURE SUB-SMALL CRAFT CONDITIONS ON ALL WATERS AS THE
PRESSURE GRADIENT RELAXES...EXCEPT FOR POSSIBLY SWELLS BRING SCA
SEAS TO THE TWO EASTERN COASTAL WATER ZONES.
GENERALLY EXPECTING SUB-SCA CONDITIONS THIS WEEKEND WITH HIGH
PRESSURE BUILDING INTO THE REGION. A BRIEF PERIOD OF INTERACTION
BETWEEN THE DEPARTING LOW AND APPROACHING HIGH FRI NIGHT COULD
INCREASE WINDS ENOUGH FROM THE NORTHWEST...COMBINED WITH COLD AIR
ADVECTION TO PRODUCE 25 KT GUSTS AND 5 FT SEAS ON THE OCEAN.
CONDITIONS THEN WILL DIMINISH BY SATURDAY.
POSSIBLE SCA CONDITIONS AGAIN NEXT MONDAY AND TUESDAY WITH THE NEXT
LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...
LITTLE ADDITIONAL ACCUMULATION OF RAIN TODAY. NO HYDROLOGIC IMPACT
IS EXPECTED.
DRY TONIGHT AND WEDNESDAY. THERE IS THE CHANCE FOR SOME LIGHT
PRECIPITATION FROM LATE WEDNESDAY NIGHT INTO THURSDAY EVENING
MAINLY OVER THE SE 1/2 OF THE TRI-STATE. AGAIN...NO HYDROLOGIC
IMPACT IS EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EDT WEDNESDAY FOR
ANZ330-335-338-340-345-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EDT WEDNESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...GOODMAN/MALOIT/SEARS
NEAR TERM...JC/GOODMAN
SHORT TERM...MALOIT
LONG TERM...SEARS
AVIATION...JM
MARINE...MALOIT/SEARS
HYDROLOGY...JC
AREA FORECAST DISCUSSION...CORRECTED
NWS NEW YORK NY
800 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COASTAL LOW WILL PASS JUST SOUTH OF LONG ISLAND TODAY...THEN
MOVE FROM THE GULF OF MAINE TONIGHT INTO THE CANADIAN MARITIMES ON
WEDNESDAY. ANOTHER COASTAL LOW WILL DEVELOP OFF THE MID ATLANTIC
COAST WEDNESDAY NIGHT...AND TRACK WELL SOUTHEAST OF LONG ISLAND
THURSDAY AND WELL EAST OF CAPE COD THURSDAY NIGHT. WEAK HIGH
PRESSURE WILL BUILD IN ON FRIDAY AND REMAIN THROUGH THE WEEKEND.
LOW PRESSURE WILL PASS TO THE SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1006 HPA SURFACE LOW ABOUT 65 MILES SOUTH OF KFRG WILL CONTINUE TO
MOVE ENE AND DEEPEN IN RESPONSE TO 3 HOURLY PRESSURE FALLS OF
2-2.5 HPA/HOUR.
PRECIPITATION WILL CONTINUE TO BE SPOTTY FOR THE REST OF THIS
MORNING - WITH ANOTHER LIGHT BATCH COMING IN LATER THIS MORNING IN
RESPONSE TO A SHORTWAVE CURRENTLY IN CENTRAL PA. IN THE WAKE OF THE
SHORTWAVE THIS AFTERNOON WILL EXPERIENCE MAINLY ISOLD TO SCT SHOWERS.
AS FOR P-TYPE - TEMPERATURES ACROSS ALL BUT THE WINTER STORM
WARNING AREA HAVE RISEN ABOVE FREEZING SO EXPECT RAIN/RAIN SHOWERS
OUTSIDE OF THE WINTER STORM WARNING AREA AND PERIODS OF ZR THIS
MORNING AND RAIN OR SNOW SHOWERS THIS AFTERNOON IN THE WARNING AREA.
BECAUSE TEMPERATURES HAVE RISEN ABOVE FREEZING ACROSS WESTERN
BERGEN AND EASTERN PASSAIC COUNTIES HAVE CANCELLED THE WINTER
WEATHER ADVISORY THERE.
FOR HIGH TEMPS...BLENDED MAV/MET WITH COLDER 04Z RAP 2M
TEMPS...WITH HIGHS ONLY NEAR 40 INLAND WHICH COULD STILL BE A
LITTLE GENEROUS ESPECIALLY ACROSS SRN CT...AND MID 40S FOR NYC
METRO AND LONG ISLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FAST W TO WSW FLOW ALOFT TONIGHT AND THURSDAY AS CLOSED LOW BUILDS
INTO NORTHERN NEW ENGLAND...THEN SE CANADA. SHOULD BE DRY TONIGHT
AND THURSDAY WITH LITTLE IF ANY IN THE WAY OF FORCING - HOWEVER IF
UPPER TROUGH AXIS IS A TAD SLOWER IN PUSHING THROUGH THAN CURRENTLY
FORECAST COULD SEE SOME -SHSN ACROSS NORTHERN ZONES EARLY THIS
EVENING. FOR LOWS TONIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. USED A BLEND OF
MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM
850 HPA NEAR THE IMMEDIATE COAST...800 HPA ACROSS FAR INTERIOR
AREAS AND 825 HPA IN BETWEEN. THIS YIELDS HIGHS AROUND 10 DEGREES
BELOW NORMAL.
A COASTAL LOW DEVELOPS OFF THE MID ATLANTIC COAST WEDNESDAY NIGHT IN
RESPONSE TO A SOUTHERN STREAM SHORTWAVE MOVING OFFSHORE - THIS LOW
THEN MOVES WELL SE OF LONG ISLAND THURSDAY AND TO THE E OF CAPE COD
THURSDAY NIGHT AS THE NORTHERN STREAM CUTOFF LOW PIVOTS TO THE SE
INTO THE TRI-STATE. THE RESULT WILL BE CHANCE POPS COASTAL
AREAS/SLIGHT CHANCE POPS ELSEWHERE FOR LIGHT SNOW FROM LATE
WEDNESDAY NIGHT INTO THURSDAY EVENING - EXCEPT OVER FAR NW ZONES
WHERE ONLY COULD SEE A FEW FLURRIES.
USED A BLEND OF MAV/MET GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH
VALUES FORECAST TO BE AROUND 5 DEGREES BELOW NORMAL. USED A BLEND
OF MIXING DOWN FROM 850 HPA NEAR THE COAST...800 HPA WELL
INLAND...AND 825 HPA IN BETWEEN...WITH A BLEND OF MAV/MET
GUIDANCE...AND NAM AND ECMWF 2-METER TEMPERATURES. THIS YIELDS
VALUES 10-15 DEGREES BELOW NORMAL. FOR LOWS THURSDAY NIGHT USED A
BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH VALUES AROUND
5 DEGREES BELOW NORMAL.
NW FLOW ALOFT FRIDAY WITH UPPER LOW OVER N AND E NEW ENGLAND - COULD
GET ENOUGH FORCING OUT OUT OF A PASSING SHORTWAVE IN THE AFTERNOON
TO WARRANT SLIGHT CHANCE POPS FOR -SHSN/-SHRA OVER FAR NW ZONES. FOR
HIGHS USED A BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH
VALUES AROUND 10 DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS BEGINNING TO COME INTO BETTER AGREEMENT WITH THE HANDLING
AND TIMING OF HIGH PRESSURE SYSTEM OVER THE COMING WEEKEND...AND
THE NEXT LOW PRESSURE SYSTEM FOR NEXT MONDAY/TUESDAY.
HIGH PRESSURE BUILDS TO THE SOUTH OVER THE NORTHEAST SATURDAY INTO
SUNDAY UNDER A BROAD UPPER LEVEL TROUGH. MULTIPLE SHORTWAVES
EXPECTED TO PASS THROUGH THE REGION WHILE ROTATING AROUND THE MAIN
UPPER LEVEL CLOSED LOW. DESPITE DECENT FORCING ASSOCIATED WITH EACH
PASSING WAVE...A PERSISTENT NORTHWESTERLY FLOW WILL KEEP A MAINLY
DRY VERTICAL COLUMN...RESULTING IN DRY CONDITIONS ACROSS THE AREA.
WHILE THE 12Z/18 RUNS HAD MUCH HIGHER DISCREPANCIES IN THE HANDLING
OF THE NEXT LOW...THE 00Z/19 RUNS ARE STARTING TO COME INTO BETTER
ALIGNMENT BUT STILL WITH SOME DIFFERENCES. LOW PRESSURE FORMS OVER
THE CENTRAL STATES ON SUNDAY...PROGRESSING TO THE EAST TO BEGIN
THE WEEK. 00Z ECMWF ACTUALLY THE MORE PROGRESSIVE OF THE SOLUTIONS...
WITH THE GFS LAGGING BEHIND WHILE DEVELOPING A SECONDARY LOW. THE
GFS THEN KEEPS THE UPPER LEVEL LOW FROM OVER THE WEEKEND NEARLY
STATIONARY...ALLOWING FOR POSSIBLE INTERACTION WITH THE NEXT LOW
TRAVERSING THE CENTRAL US...RESULTING IN MORE WIDESPREAD
PRECIPITATION. HOWEVER...THE PATTERN OF THE ECMWF KEEPS THE
TRAVERSING LOW TO THE SOUTH...BUILDING IN SUBSIDENCE OVER MOST OF
THE NORTHEAST...KEEPING THE HEAVIEST PRECIPITATION TO THE SOUTH.
BECAUSE OF THE MODEL SPREAD...CONTINUED THE SLIGHT CHANCE POPS FOR
MONDAY INTO TUESDAY.
GENERALLY USED A BLEND OF THE WPC AND MOS GUIDANCE FOR TEMPS THIS
WEEKEND INTO NEXT WEEK...WHICH KEEPS HIGH TEMPS SLIGHTLY BELOW
NORMAL AND OVERNIGHT LOWS RIGHT AROUND TO SLIGHTLY BELOW NORMAL.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE WILL TRACK FROM THE DELMARVA TO JUST SOUTHEAST OF
NYC THIS MORNING. THE LOW PRESSURE MOVES INTO COASTAL NEW ENGLAND
THIS EVENING. INITIALLY EASTERLY GUSTS OF AROUND 20 KT WILL LOWER
AND WINDS OVERALL BECOME LIGHT AND VARIABLE LATER THIS MORNING
BEFORE BECOMING MORE WESTERLY BY THE AFTERNOON...GUSTING 20-25 KT
LATE. THERE IS SOME UNCERTAINTY ON TIMING OF THE SWITCHING
DIRECTIONS AND THE LIGHT AND VARIABLE TRANSITION COULD BE OFF BY
1-2 HOURS AS WELL AS WHEN THE WINDS BECOME WESTERLY.
ICING MAINLY RESTRICTED TO KSWF WHERE THERE IS FREEZING DRIZZLE THIS
MORNING. FOR KSWF...STORM TOTAL SNOW OF ABOUT 7 INCHES WITH ABOUT
A TENTH OF AN INCH OF ICE. ELSEWHERE...THE PRECIP TYPE IS RAIN FOR
EASTERN TERMINALS AND DRIZZLE TO THE WEST. ALL PRECIP BECOMES
DRIZZLE LATER THIS MORNING...LINGERING INTO THE AFTERNOON. MAINLY
IFR CONDITIONS WITH SOME POCKETS OF POSSIBLE LIFR WITH NO
SUBSTANTIAL IMPROVEMENT EXPECTED UNTIL WINDS BECOME MORE WESTERLY
AND START GUSTING LATE IN THE AFTERNOON GENERALLY AFTER 20Z.
POSSIBLE VLIFR POSSIBLE IN FOG THIS MORNING WHEN LOW IS WITHIN
CLOSEST PROXIMITY OF THE TERMINALS. VFR RETURNS BY THE EVENING
WITH WEST WINDS GUSTING TO 25-30 KT...DECREASING A FEW KTS
OVERNIGHT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KLGA FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KEWR FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KHPN FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KISP FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
.OUTLOOK FOR 12Z WED THROUGH SAT...
.WED...GENERALLY VFR. W WINDS WITH GUSTS INTO THE LOWER 20 KT
RANGE ON WED.
.THU...CHANCE OF SUB-VFR IN LIGHT SNOW.
.FRI...VFR. GUSTY NW WINDS POSSIBLE.
.SAT...VFR.
&&
.MARINE...
MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
NON ELEVATED OBSERVATIONS ACROSS THE COASTAL OCEAN WATERS INDICATE
THAT GALE FORCE GUSTS HAVE COME TO AN END - SO HAVE ALLOWED GALE
WARNING TO COME TO AN END AND HAVE REPLACED IT WITH A SMALL CRAFT
ADVISORY FOR ALL WATERS FOR TODAY. WHILE SHELTERED WATERS...
ESPECIALLY NY HARBOR AND PORTIONS OF W LONG ISLAND SOUND WILL
HAVE PERIODS OF WINDS BELOW SMALL CRAFT LEVELS - EXPECT THEM TO BE
RELATIVELY SHORT IN DURATION.
WINDS INCREASE TONIGHT AS COASTAL LOW DEEPENS TO THE EAST - SO
HAVE ISSUED A GALE WARNING FOR ALL WATERS FOR TONIGHT. GALE GUSTS
CONTINUE ON WEDNESDAY OVER EASTERN COASTAL OCEAN WATERS -
ANZ350-353 - WITH SMALL CRAFT CONDITIONS ELSEWHERE. THE PRESSURE
GRADIENT RELAXES OVER THE REGION WEDNESDAY NIGHT...WITH ALL WATERS
FALLING BELOW SCA LEVELS AFTER MIDNIGHT..AND CONTINUE ON THURSDAY.
WIND GUSTS ON THE COASTAL OCEAN WATERS COULD REACH 25 KT THURSDAY
NIGHT IN THE WAKE OF THE DEPARTING...BUT STRENGTHENING COASTAL
LOW...WITH SUB-SMALL CRAFT CONDITIONS ON THE REMAINDER OF THE WATERS.
FRIDAY WILL FEATURE SUB-SMALL CRAFT CONDITIONS ON ALL WATERS AS THE
PRESSURE GRADIENT RELAXES...EXCEPT FOR POSSIBLY SWELLS BRING SCA
SEAS TO THE TWO EASTERN COASTAL WATER ZONES.
GENERALLY EXPECTING SUB-SCA CONDITIONS THIS WEEKEND WITH HIGH
PRESSURE BUILDING INTO THE REGION. A BRIEF PERIOD OF INTERACTION
BETWEEN THE DEPARTING LOW AND APPROACHING HIGH FRI NIGHT COULD
INCREASE WINDS ENOUGH FROM THE NORTHWEST...COMBINED WITH COLD AIR
ADVECTION TO PRODUCE 25 KT GUSTS AND 5 FT SEAS ON THE OCEAN.
CONDITIONS THEN WILL DIMINISH BY SATURDAY.
POSSIBLE SCA CONDITIONS AGAIN NEXT MONDAY AND TUESDAY WITH THE NEXT
LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...
LIQUID EQUIVALENT STORM TOTAL QPF OF 1.00-1.25 INCHES EXPECTED.
PRECIP LIGHT ENOUGH AT THIS TIME THAT COMBINED LIGHT RAIN AND SNOW
MELT SHOULD NOT CAUSE MUCH IN THE WAY OF PROBLEMS.
DRY TONIGHT AND WEDNESDAY. THERE IS THE CHANCE FOR SOME LIGHT
PRECIPITATION FROM LATE WEDNESDAY NIGHT INTO THURSDAY EVENING
MAINLY OVER THE SE 1/2 OF THE TRI-STATE. NO HYDROLOGIC IMPACT
IS EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
CTZ005>008.
NY...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
NYZ067>070.
NJ...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR NJZ002.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EDT WEDNESDAY FOR
ANZ330-335-338-340-345-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EDT WEDNESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...GOODMAN/MALOIT/SEARS
NEAR TERM...MALOIT/GOODMAN
SHORT TERM...MALOIT
LONG TERM...SEARS
AVIATION...JM
MARINE...MALOIT/SEARS
HYDROLOGY...GOODMAN
AREA FORECAST DISCUSSION
NWS NEW YORK NY
755 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COASTAL LOW WILL PASS JUST SOUTH OF LONG ISLAND TODAY...THEN
MOVE FROM THE GULF OF MAINE TONIGHT INTO THE CANADIAN MARITIMES ON
WEDNESDAY. ANOTHER COASTAL LOW WILL DEVELOP OFF THE MID ATLANTIC
COAST WEDNESDAY NIGHT...AND TRACK WELL SOUTHEAST OF LONG ISLAND
THURSDAY AND WELL EAST OF CAPE COD THURSDAY NIGHT. WEAK HIGH
PRESSURE WILL BUILD IN ON FRIDAY AND REMAIN THROUGH THE WEEKEND.
LOW PRESSURE WILL PASS TO THE SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1006 HPA SURFACE LOW ABOUT 65 MILES SOUTH OF KFRG WILL CONTINUE TO
MOVE ENE AND DEEPEN IN RESPONSE TO 3 HOURLY PRESSURE FALLS OF
2-2.5 HPA/HOUR.
PRECIPITATION WILL CONTINUE TO BE SPOTTY FOR THE REST OF THIS
MORNING - WITH ANOTHER LIGHT BATCH COMING IN LATER THIS MORNING IN
RESPONSE TO A SHORTWAVE CURRENTLY IN CENTRAL PA. IN THE WAKE OF THE
SHORTWAVE THIS AFTERNOON WILL EXPERIENCE MAINLY ISOLD TO SCT SHOWERS.
AS FOR P-TYPE - TEMPERATURES ACROSS ALL BUT THE WINTER STORM
WARNING AREA HAVE RISEN ABOVE FREEZING SO EXPECT RAIN/RAIN SHOWERS
OUTSIDE OF THE WINTER STORM WARNING AREA AND PERIODS OF ZR THIS
MORNING AND RAIN OR SNOW SHOWERS THIS AFTERNOON IN THE WARNING AREA.
BECAUSE TEMPERATURES HAVE RISEN ABOVE FREEZING ACROSS WESTERN
BERGEN AND EASTERN PASSAIC COUNTIES HAVE CANCELLED THE WINTER
WEATHER ADVISORY THERE.
FOR HIGH TEMPS...BLENDED MAV/MET WITH COLDER 04Z RAP 2M
TEMPS...WITH HIGHS ONLY NEAR 40 INLAND WHICH COULD STILL BE A
LITTLE GENEROUS ESPECIALLY ACROSS SRN CT...AND MID 40S FOR NYC
METRO AND LONG ISLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FAST W TO WSW FLOW ALOFT TONIGHT AND THURSDAY AS CLOSED LOW BUILDS
INTO NORTHERN NEW ENGLAND...THEN SE CANADA. SHOULD BE DRY TONIGHT
AND THURSDAY WITH LITTLE IF ANY IN THE WAY OF FORCING - HOWEVER IF
UPPER TROUGH AXIS IS A TAD SLOWER IN PUSHING THROUGH THAN CURRENTLY
FORECAST COULD SEE SOME -SHSN ACROSS NORTHERN ZONES EARLY THIS
EVENING. FOR LOWS TONIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. USED A BLEND OF
MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM
850 HPA NEAR THE IMMEDIATE COAST...800 HPA ACROSS FAR INTERIOR
AREAS AND 825 HPA IN BETWEEN. THIS YIELDS HIGHS AROUND 10 DEGREES
BELOW NORMAL.
A COASTAL LOW DEVELOPS OFF THE MID ATLANTIC COAST WEDNESDAY NIGHT IN
RESPONSE TO A SOUTHERN STREAM SHORTWAVE MOVING OFFSHORE - THIS LOW
THEN MOVES WELL SE OF LONG ISLAND THURSDAY AND TO THE E OF CAPE COD
THURSDAY NIGHT AS THE NORTHERN STREAM CUTOFF LOW PIVOTS TO THE SE
INTO THE TRI-STATE. THE RESULT WILL BE CHANCE POPS COASTAL
AREAS/SLIGHT CHANCE POPS ELSEWHERE FOR LIGHT SNOW FROM LATE
WEDNESDAY NIGHT INTO THURSDAY EVENING - EXCEPT OVER FAR NW ZONES
WHERE ONLY COULD SEE A FEW FLURRIES.
USED A BLEND OF MAV/MET GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH
VALUES FORECAST TO BE AROUND 5 DEGREES BELOW NORMAL. USED A BLEND
OF MIXING DOWN FROM 850 HPA NEAR THE COAST...800 HPA WELL
INLAND...AND 825 HPA IN BETWEEN...WITH A BLEND OF MAV/MET
GUIDANCE...AND NAM AND ECMWF 2-METER TEMPERATURES. THIS YIELDS
VALUES 10-15 DEGREES BELOW NORMAL. FOR LOWS THURSDAY NIGHT USED A
BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH VALUES AROUND
5 DEGREES BELOW NORMAL.
NW FLOW ALOFT FRIDAY WITH UPPER LOW OVER N AND E NEW ENGLAND - COULD
GET ENOUGH FORCING OUT OUT OF A PASSING SHORTWAVE IN THE AFTERNOON
TO WARRANT SLIGHT CHANCE POPS FOR -SHSN/-SHRA OVER FAR NW ZONES. FOR
HIGHS USED A BLEND OF MEX/MEX ENSEMBLE MEAN/ECE/WPC GUIDANCE WITH
VALUES AROUND 10 DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS BEGINNING TO COME INTO BETTER AGREEMENT WITH THE HANDLING
AND TIMING OF HIGH PRESSURE SYSTEM OVER THE COMING WEEKEND...AND
THE NEXT LOW PRESSURE SYSTEM FOR NEXT MONDAY/TUESDAY.
HIGH PRESSURE BUILDS TO THE SOUTH OVER THE NORTHEAST SATURDAY INTO
SUNDAY UNDER A BROAD UPPER LEVEL TROUGH. MULTIPLE SHORTWAVES
EXPECTED TO PASS THROUGH THE REGION WHILE ROTATING AROUND THE MAIN
UPPER LEVEL CLOSED LOW. DESPITE DECENT FORCING ASSOCIATED WITH EACH
PASSING WAVE...A PERSISTENT NORTHWESTERLY FLOW WILL KEEP A MAINLY
DRY VERTICAL COLUMN...RESULTING IN DRY CONDITIONS ACROSS THE AREA.
WHILE THE 12Z/18 RUNS HAD MUCH HIGHER DISCREPANCIES IN THE HANDLING
OF THE NEXT LOW...THE 00Z/19 RUNS ARE STARTING TO COME INTO BETTER
ALIGNMENT BUT STILL WITH SOME DIFFERENCES. LOW PRESSURE FORMS OVER
THE CENTRAL STATES ON SUNDAY...PROGRESSING TO THE EAST TO BEGIN
THE WEEK. 00Z ECMWF ACTUALLY THE MORE PROGRESSIVE OF THE SOLUTIONS...
WITH THE GFS LAGGING BEHIND WHILE DEVELOPING A SECONDARY LOW. THE
GFS THEN KEEPS THE UPPER LEVEL LOW FROM OVER THE WEEKEND NEARLY
STATIONARY...ALLOWING FOR POSSIBLE INTERACTION WITH THE NEXT LOW
TRAVERSING THE CENTRAL US...RESULTING IN MORE WIDESPREAD
PRECIPITATION. HOWEVER...THE PATTERN OF THE ECMWF KEEPS THE
TRAVERSING LOW TO THE SOUTH...BUILDING IN SUBSIDENCE OVER MOST OF
THE NORTHEAST...KEEPING THE HEAVIEST PRECIPITATION TO THE SOUTH.
BECAUSE OF THE MODEL SPREAD...CONTINUED THE SLIGHT CHANCE POPS FOR
MONDAY INTO TUESDAY.
GENERALLY USED A BLEND OF THE WPC AND MOS GUIDANCE FOR TEMPS THIS
WEEKEND INTO NEXT WEEK...WHICH KEEPS HIGH TEMPS SLIGHTLY BELOW
NORMAL AND OVERNIGHT LOWS RIGHT AROUND TO SLIGHTLY BELOW NORMAL.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE WILL TRACK FROM THE DELMARVA TO JUST SOUTHEAST OF
NYC THIS MORNING. THE LOW PRESSURE MOVES INTO COASTAL NEW ENGLAND
THIS EVENING. INITIALLY EASTERLY GUSTS OF AROUND 20 KT WILL LOWER
AND WINDS OVERALL BECOME LIGHT AND VARIABLE LATER THIS MORNING
BEFORE BECOMING MORE WESTERLY BY THE AFTERNOON...GUSTING 20-25 KT
LATE. THERE IS SOME UNCERTAINTY ON TIMING OF THE SWITCHING
DIRECTIONS AND THE LIGHT AND VARIABLE TRANSITION COULD BE OFF BY
1-2 HOURS AS WELL AS WHEN THE WINDS BECOME WESTERLY.
ICING MAINLY RESTRICTED TO KSWF WHERE THERE IS FREEZING DRIZZLE THIS
MORNING. FOR KSWF...STORM TOTAL SNOW OF ABOUT 7 INCHES WITH ABOUT
A TENTH OF AN INCH OF ICE. ELSEWHERE...THE PRECIP TYPE IS RAIN FOR
EASTERN TERMINALS AND DRIZZLE TO THE WEST. ALL PRECIP BECOMES
DRIZZLE LATER THIS MORNING...LINGERING INTO THE AFTERNOON. MAINLY
IFR CONDITIONS WITH SOME POCKETS OF POSSIBLE LIFR WITH NO
SUBSTANTIAL IMPROVEMENT EXPECTED UNTIL WINDS BECOME MORE WESTERLY
AND START GUSTING LATE IN THE AFTERNOON GENERALLY AFTER 20Z.
POSSIBLE VLIFR POSSIBLE IN FOG THIS MORNING WHEN LOW IS WITHIN
CLOSEST PROXIMITY OF THE TERMINALS. VFR RETURNS BY THE EVENING
WITH WEST WINDS GUSTING TO 25-30 KT...DECREASING A FEW KTS
OVERNIGHT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KLGA FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KEWR FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KHPN FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
KISP FCSTER COMMENTS: LOW CONFIDENCE WITH VSBYS FORECAST. TIMING
OF IFR VSBYS COULD BE OFF BY A FEW HOURS. HIGH CONFIDENCE WITH
CIGS FORECAST. WIND SHIFT TO NW COULD BE 1-2 HOURS OFF. AMENDMENTS
POSSIBLE.
.OUTLOOK FOR 12Z WED THROUGH SAT...
.WED...GENERALLY VFR. W WINDS WITH GUSTS INTO THE LOWER 20 KT
RANGE ON WED.
.THU...CHANCE OF SUB-VFR IN LIGHT RAIN OR SNOW.
.FRI...VFR. GUSTY NW WINDS POSSIBLE.
.SAT...VFR.
&&
.MARINE...
MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
NON ELEVATED OBSERVATIONS ACROSS THE COASTAL OCEAN WATERS INDICATE
THAT GALE FORCE GUSTS HAVE COME TO AN END - SO HAVE ALLOWED GALE
WARNING TO COME TO AN END AND HAVE REPLACED IT WITH A SMALL CRAFT
ADVISORY FOR ALL WATERS FOR TODAY. WHILE SHELTERED WATERS...
ESPECIALLY NY HARBOR AND PORTIONS OF W LONG ISLAND SOUND WILL
HAVE PERIODS OF WINDS BELOW SMALL CRAFT LEVELS - EXPECT THEM TO BE
RELATIVELY SHORT IN DURATION.
WINDS INCREASE TONIGHT AS COASTAL LOW DEEPENS TO THE EAST - SO
HAVE ISSUED A GALE WARNING FOR ALL WATERS FOR TONIGHT. GALE GUSTS
CONTINUE ON WEDNESDAY OVER EASTERN COASTAL OCEAN WATERS -
ANZ350-353 - WITH SMALL CRAFT CONDITIONS ELSEWHERE. THE PRESSURE
GRADIENT RELAXES OVER THE REGION WEDNESDAY NIGHT...WITH ALL WATERS
FALLING BELOW SCA LEVELS AFTER MIDNIGHT..AND CONTINUE ON THURSDAY.
WIND GUSTS ON THE COASTAL OCEAN WATERS COULD REACH 25 KT THURSDAY
NIGHT IN THE WAKE OF THE DEPARTING...BUT STRENGTHENING COASTAL
LOW...WITH SUB-SMALL CRAFT CONDITIONS ON THE REMAINDER OF THE WATERS.
FRIDAY WILL FEATURE SUB-SMALL CRAFT CONDITIONS ON ALL WATERS AS THE
PRESSURE GRADIENT RELAXES...EXCEPT FOR POSSIBLY SWELLS BRING SCA
SEAS TO THE TWO EASTERN COASTAL WATER ZONES.
GENERALLY EXPECTING SUB-SCA CONDITIONS THIS WEEKEND WITH HIGH
PRESSURE BUILDING INTO THE REGION. A BRIEF PERIOD OF INTERACTION
BETWEEN THE DEPARTING LOW AND APPROACHING HIGH FRI NIGHT COULD
INCREASE WINDS ENOUGH FROM THE NORTHWEST...COMBINED WITH COLD AIR
ADVECTION TO PRODUCE 25 KT GUSTS AND 5 FT SEAS ON THE OCEAN.
CONDITIONS THEN WILL DIMINISH BY SATURDAY.
POSSIBLE SCA CONDITIONS AGAIN NEXT MONDAY AND TUESDAY WITH THE NEXT
LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...
LIQUID EQUIVALENT STORM TOTAL QPF OF 1.00-1.25 INCHES EXPECTED.
PRECIP LIGHT ENOUGH AT THIS TIME THAT COMBINED LIGHT RAIN AND SNOW
MELT SHOULD NOT CAUSE MUCH IN THE WAY OF PROBLEMS.
DRY TONIGHT AND WEDNESDAY. THERE IS THE CHANCE FOR SOME LIGHT
PRECIPITATION FROM LATE WEDNESDAY NIGHT INTO THURSDAY EVENING
MAINLY OVER THE SE 1/2 OF THE TRI-STATE. NO HYDROLOGIC IMPACT
IS EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
CTZ005>008.
NY...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR
NYZ067>070.
NJ...WINTER STORM WARNING UNTIL 10 AM EDT THIS MORNING FOR NJZ002.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EDT WEDNESDAY FOR
ANZ330-335-338-340-345-355.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EDT WEDNESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...GOODMAN/MALOIT/SEARS
NEAR TERM...MALOIT/GOODMAN
SHORT TERM...MALOIT
LONG TERM...SEARS
AVIATION...JM
MARINE...MALOIT/SEARS
HYDROLOGY...GOODMAN
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
946 AM EDT TUE MAR 19 2013
.SYNOPSIS...
LOW PRESSURE EAST OF NEW JERSEY THIS MORNING WILL CONTINUE TO
DEEPEN WHILE MOVING TOWARD NEW ENGLAND BY TONIGHT. A RIDGE OF HIGH
PRESSURE WILL MOVE IN WEDNESDAY BEFORE A COLD FRONT CROSSES THE
AREA DURING THE AFTERNOON. AN AREA OF LOW PRESSURE WILL FORM ALONG
THE FRONT WEDNESDAY NIGHT AND MOVE OUT INTO THE ATLANTIC THURSDAY.
EXTENSIVE HIGH PRESSURE CENTERED IN NORTHERN CANADA WILL DOMINATE
MUCH OF NORTH AMERICA FRIDAY AND SATURDAY. LOW PRESSURE DEVELOPING
ALONG THE GULF COAST NEXT WEEKEND WILL NEED TO BE MONITORED FOR A
POSSIBLE TURN UP THE COAST EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE WINTER STORM WARNING WAS CANCELLED EARLIER BUT REPLACED BY A
WINTE WEATHER ADVISORY UNTIL 1000 AM...AND THE REMAINING ADVISORY
WAS ALSO EXTENDED TO 1000 AM. TEMPERATURES ARE SLOWLY WARMING BUT
REMAIN BELOW FREEZING AT SOME HIGHER ELEVATIONS. WILL LET THE
ADVISORY EXPIRE ALTHO A FEW HIGHEST ELEVATIONS MIGHT STAY AT OR
BELOW FREEZING FOR ANOTHER HOUR OR TWO. WE HAVE ALSO RECEIVED A
REPORT OF RAIN CHANGING BACK TO SNOW OVER THE POCONOS AS COLDER
AIR MOVES IN ALOFT
OTRW SOME MORNING PATCHY FOG CONTINUES. AS ANTICIPATED...ANOTHER
BAND OF RAIN IS MOVING ACROSS EASTER PA AND MUCH OF NEW JERSEY.
PRECIP AMOUNTS FROM THIS BAND SHOULD BE JUST A FEW HUNDREDTHS OF
AN INCH.
DURING EARLY TO MID AFTERNOON WLY FLOW WILL INCREASE AND CLEARING
WILL TAKE PLACE FM WEST TO EAST AS AN UPPER IMPLS MOVES PAST THE
AREA. THIS IS A LITTLE BIT LATER THAN PREVIIOUS THINKING. GUSTY W
WIND THIS AFTN 25-30 MPH AND POSSIBLY THE MILDEST DAY OF THE WEEK
AND PROBABLY THE MILDEST SINCE THE 15TH. NEAR NORMAL TEMPS.
STG NEG TILT TROUGH ROLLING THRU PA AND NJ LATE TODAY AND PER SPC WRF
HAVE A CHANCE OF LATE AFTN/EVE SHOWERS FM W TO E ACROSS PA.
PROBABLY OCCURS IN SHORT N-S LINES.
OTRW THE FCST WAS BLENDED 00Z/19 NCEP MOS WITH A LEAN COLDER IN YDYS
SNOW ACCUM AREA N OF I78.
OUR PUBLIC INFO STATEMENT ON SNOWFALL WAS UPDATED AT 900 AM AND
THIS SHOULD BE THE FINAL STATEMENT FOR THIS EVENT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
TONIGHT...CLEAR TO PC WITH GUSTY WNW WINDS DIMINISHING A BIT.
THE FCST WAS BASED ON BLENDED 00Z/19 NCEP MOS GUIDANCE. A FEW
FLURRIES POSSIBLE IN THE POCONOS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
ONE MINOR SYSTEM AND THE POTENTIAL FOR A MORE SIGNIFICANT SYSTEM
AWAIT US IN THE LONG TERM PART OF THE FORECAST. THE UPPER TROUGH
ACROSS THE NORTHEAST AT THE BEGINNING OF THE PERIOD MOVES AWAY
THIS WEEKEND...BEFORE ANOTHER PROGRESSIVE H5 LOW FROM THE PLAINS
MOVES TOWARD THE REGION EARLY NEXT WEEK. TEMPERATURES WILL REMAIN
BELOW NORMAL THROUGH THE PERIOD WITH SOME MODERATION POSSIBLE
EARLY NEXT WEEK.
WEDNESDAY...THE UPPER LOW TO THE NORTH WILL BE SENDING AN UPPER
TROUGH ACROSS THE AREA WEDNESDAY ACCOMPANIED BY A MOSTLY DRY SFC
COLD FRONT. WE KEPT POPS BELOW SLGT CHC FOR NOW WITH A MOSTLY DRY
AIR MASS IN PLACE.
WED NIGHT INTO EARLY THU...WEAK LOW PRESSURE IS SHOWN DEVELOPING
ON THE COLD FRONT...WHICH WILL BE SOUTH OF THE AREA AT THIS
TIME...AND MOVING OFFSHORE LATE WED NIGHT. THERE IS THE CHC FOR
SOME SNOW LATE WED NIGHT INTO THU FOR DE/ERN NJ ASSOCIATED WITH
THIS LOW. WE KEPT THE POPS IN THE CHC RANGE FOR NOW AND PAINTED IN
SOME 0.5 - 1.0 INCH SNOW ACCUMS POSSIBLE. LOW CONFID IN THE TRACK
PRECIP FCST WITH THIS LOW.
THU INTO SUN... A MOSTLY DRY PERIOD IS EXPECTED WITH THE UPPER LOW
MOVING AWAY AND A SFC HIGH PRESSURE SYSTEM FROM CANADA EXTENDING
ITS INFLUENCE ACROSS THE AREA. SNOW SHOWERS ARE POSSIBLE ACROSS
THE SRN POCONOS...BUT ONLY SLGT CHCS ARE IN THE GRIDS ATTM.
SUN NIGHT INTO MONDAY...A PROGRESSIVE UPPER/SFC LOW IS SHOWN
MOVING ACROSS FROM THE SRN PLAINS INTO THE THE TENN VALLEY BY MON
MORNING. THE SYSTEM CONTINUES EASTWARD AND A SECOND LOW IS SHOWN
FORMING ALONG THE EAST COAST. THE 00Z EC MODEL BRINGS QPF ACROSS
THE SRN HALF OF THE FCST AREA MONDAY WITH THIS FEATURE. WE HAVE
CHC POPS IN THE GRIDS FOR NOW. THIS WILL BE THE SYSTEM TO WATCH
OVER THE NEXT SEVERAL DAYS.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TODAY...IFR CONDS IN RAIN/DRIZZLE FOG WITH POSSIBLE LIFR CONDS IN
SPOTTY DENSE FOG THROUGH ABOUT 16 OR 17Z. THIS IS A LITTLE LATER
THAN PREVIOUS THINKING BUT IS SUPPORTED BY THE LATEST RAP MODEL
GUIDANCE.
WIND TURNS W DURING EARLY TO MID AFTERNOON AND INCREASES WITH
AFTN GUSTS TO 25 OR 30 KTS AND CONDS BECOMING VFR SCT-BKN AOA 3500
FT DURING MIDDAY. CHANCE OF BRIEF MVFR CONDS IN A LATE AFTN SHOWER
ASSOCIATED WITH A STRONG NEG TILT VORT MAX CROSSING PA AND NJ.
TONIGHT...VFR SCT CLDS AOA 5000 FT WITH CHANCE OF FLURRIES AND
BRIEF MVFR CONDS IN THE POCONOS. GUSTY WNW WIND TO 20 TO 25 KTS
DIMINISH LATE.
OUTLOOK...
WED...MOSTLY VFR EXPECTED WITH GUSTY WEST WINDS.
WED NIGHT INTO EARLY THU...VFR WEST. CLOUDS AND POSSIBLE MVFR IN
LIGHT SNOW ACROSS ERN NJ AND SRN/ERN DE.
THU THRU SAT...MOSTLY VFR. A FEW SNOW SHOWERS POSSIBLE ACROSS THE
SRN POCONOS.
&&
.MARINE...
FROM SANDY HOOK TO 44065...ISSUED SCA FOR THE DAY AND CONT GLW
THERE TONIGHT. OTRW SCA ON ALL THE REMAINING ATLC WATERS THROUGH
WED.
WE MAY NEED TO UPGRADE TO A GLW TONIGHT ALONG PORTIONS OF THE ATLC
WATERS....ESP VCNTY ENTRANCE TO DE BAY DOWN TO 44009 NEAR 06Z.
MIXED MODEL SIGNALS ON WHERE THE BEST TRANSFER WILL OCCUR. NOT
ENOUGH MODEL SUPPORT TO GO WIDESPREAD ON A GALE IN THIS EARLY
MORNING FCST PACKAGE.
THE GLW VERIFICATION IN ANZ450 WAS FROM SANDY HOOK TO 44065 FROM
ROUGHLY 22Z YDY THROUGH 08Z THIS MORNING WITH A PEAK GUST OF 41 KT
AT 44065 AND MULTIPLE 37 KT AT SHOOK...ON THE NRN FRINGE OF ANZ
450.
OUTLOOK...
SCA CONDITIONS WITH GUSTY WEST TO NORTHWEST WINDS WED INTO
THU...THEN SUB-SCA CONDITIONS INTO THE WEEKEND. POTENTIAL FOR A
MORE SIGNIFICANT MARINE STORM EARLY NEXT WEEK.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
PAZ054-055-060>062.
NJ...WINTER WEATHER ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
NJZ001-007-008.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT WEDNESDAY FOR ANZ451>455.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ450.
GALE WARNING FROM 6 PM THIS EVENING TO 4 AM EDT WEDNESDAY FOR
ANZ450.
SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 6 AM EDT
WEDNESDAY FOR ANZ430-431.
&&
$$
SYNOPSIS...O`HARA
NEAR TERM...AMC
SHORT TERM...DRAG
LONG TERM...O`HARA
AVIATION...AMC/O`HARA
MARINE...AMC/O`HARA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
935 AM EDT TUE MAR 19 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE AREA FROM THE NORTHWEST TODAY...
FOLLOWED BY HIGH PRESSURE THROUGH WEDNESDAY AND ANOTHER COLD
FRONTAL PASSAGE WEDNESDAY NIGHT. RAIN CHANCES WILL INCREASE LATE
IN THE WEEK AND OVER THE WEEKEND AS A COUPLE LOW PRESSURE SYSTEMS
MOVE OVER OR JUST SOUTH OF THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE COLD FRONT WILL MEANDER CLOSER TO THE COAST TODAY. THERE ARE
SIGNS THAT THE FRONT WILL BECOME INTERMINGLED WITHIN A DEVELOPING
SEA BREEZE LATER THIS AFTERNOON. RAP INSTABILITY PROGS SUGGEST A
SMALL POCKET OF INSTABILITY FEATURING LIFTED INDICES AS LOW AS -3C
WOULD DEVELOP FROM ROUGHLY BEAUFORT SOUTH TO SAVANNAH...DARIEN
AND LUDOWICI SHORTLY AFTER NOON...BUT THINK BY THAT TIME MOST OF
THE DEEPEST MOISTURE WILL BE SCOURING OUT AS DOWNSLOPE MID-LEVEL
TRAJECTORIES TAKE HOLD. WILL GO WITH A RAIN-FREE FORECAST FOR
TODAY...BUT IT WILL BE INTERESTING TO SEE IF A TSTM OR TWO COULD
POP IN THE SAID INSTABILITY CORRIDOR. OTHERWISE...LOWERED HIGH
TEMPERATURES JUST A BIT PER CURRENT SHORT TERM GUIDANCE. EXPECT
SKIES WILL CLEAR RAPIDLY FROM WEST-EAST THROUGH THE AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
COLD ADVECTION WILL PUSH OVERNIGHT TEMPERATURES INTO THE 40S AT
MOST LOCATIONS TONIGHT. ALONG THE IMMEDIATE COAST...NE WINDS WILL
HOLD TEMPS IN THE 50S. SKIES ARE EXPECTED TO START MOSTLY
CLEAR...THEN MODEL SOUNDINGS DEPICT INCREASING HIGH CLOUDS AS THE
NIGHT PROGRESSES.
DECENT CONFIDENCE THIS PERIOD. SURFACE HIGH PRESSURE WILL BE RIDGING
EASTWARD ACROSS THE CAROLINAS TO START THE DAY BUT A BACKDOOR COLD
FRONT WILL BE APPROACHING FROM THE NORTHWEST LATE IN THE DAY.
ALSO...LOW PRESSURE IS EXPECTED TO DEVELOP SOUTH AND SOUTHEAST OF
THE AREA. THE LOW COULD BE CLOSE ENOUGH AND MOISTURE DEEP ENOUGH TO
SQUEEZE OUT A FEW LIGHT SHOWERS...MAINLY ALONG THE COASTAL AREAS.
OTHERWISE IT WILL BE A COOL DAY WITH BELOW NORMAL TEMPERATURES IN
THE 60S...POSSIBLY COOLER DEPENDING ON THE CLOUD/RAIN COVERAGE.
COLDER HIGH PRESSURE WILL THEN MOVE IN WEDNESDAY NIGHT BEHIND A
REINFORCING COLD FRONT. TEMPERATURES COULD GET DOWN TO FREEZING WELL
INLAND TOWARD DAYBREAK THURSDAY AND A FREEZE WATCH MAY NEED TO BE
CONSIDERED. THE UPPER TROUGH AXIS LOOKS TO SHIFT OFFSHORE THURSDAY
WITH A COOL AIRMASS LINGERING OVER THE AREA. IT WILL BE DRY AND A
BIT BREEZY WITH TEMPERATURES POSSIBLY NOT GETTING OUT OF THE
50S...ESPECIALLY ACROSS SOUTHERN SOUTH CAROLINA. SURFACE HIGH
PRESSURE WILL SHIFT OVER THE AREA THURSDAY NIGHT AS MOISTURE BEGINS
TO INCREASE FROM THE WEST IN ASSOCIATION WITH LOW PRESSURE OVER
TEXAS. THERE COULD BE A FEW SHOWERS LATE...MAINLY WELL INLAND.
AGAIN...THERE COULD BE SOME FREEZING TEMPERATURES WELL INLAND ALONG
WITH SOME FROST BUT MUCH DEPENDS ON HOW QUICKLY THE CLOUD COVER
INCREASES AND THE RESULTANT EFFECT ON RADIATIONAL COOLING. ANOTHER
CHILLY DAY EXPECTED ON FRIDAY WITH INCREASED CLOUD COVER AND SOME
SHOWERS. TEMPERATURES COULD STRUGGLE TO GET OUT OF THE 50S AGAIN.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
CONFIDENCE REMAINS LOW IN THE EXACT DETAILS THIS PERIOD AS THERE ARE
STILL MODEL DISCREPANCIES REGARDING THE LATE WEEK/WEEKEND
PERIOD...PARTICULARLY WITH THE TRACK AND TIMING OF SEVERAL WAVES OF
LOW PRESSURE WHICH WILL BE RIDING ALONG A WARM FRONT LIKELY DRAPED
ACROSS SOUTHEAST GEORGIA. EXPECT HIGH RAIN CHANCES AND BELOW NORMAL
TEMPERATURES THROUGH SUNDAY WITH LOWER RAIN CHANCES AND SOME WARMER
TEMPERATURES LIKELY ON MONDAY. RAINFALL TOTALS THROUGH THE PERIOD
COULD REACH ONE OR TWO INCHES...POSSIBLY A BIT MORE...ESPECIALLY
ACROSS SOUTHEAST GEORGIA.
TEMPERATURES WILL BE RATHER TRICKY BUT LOOK TO REMAIN BELOW NORMAL
THROUGH THE PERIOD. IT IS CERTAINLY POSSIBLE THAT SOME
AREAS...ESPECIALLY INTERIOR PORTIONS OF SOUTHEAST SC/GA...DO NOT GET
OUT OF THE 50S THROUGH SUNDAY WITH THE WEDGE PATTERN IN PLACE.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
OCCASIONAL IFR/LIFT CONDITIONS WILL TRANSITION TO OCCASIONAL MVFR
CEILINGS 14-17Z...THEN VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT
AS MUCH DRIER AIR SPREADS ACROSS THE REGION.
EXTENDED AVIATION OUTLOOK...MOSTLY VFR THROUGH FRIDAY WITH INCREASE
CHANCES OF SUB-VFR CONDITIONS THROUGH THE WEEKEND AS SEVERAL LOW
PRESSURE SYSTEMS ARE EXPECTED TO MOVE OVER OR JUST SOUTH OF KSAV.
BREEZY/GUSTY CONDITIONS EXPECTED THURSDAY.
&&
.MARINE...
TODAY...THE COLD FRONT LOOKS TO GET INTERMINGLED WITH THE SEA
BREEZE LATER TODAY...SO EXPECT A PERIOD OF VARIABLE WINDS TO
DEVELOP OVER MOST LEGS THIS AFTERNOON. BOTH WINDS AND SEAS WILL
REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS.
OVERNIGHT...NE WINDS WILL SURGE TO 15-20 KT AND SEAS WILL BUILD
TO 3-5 FT. NO SMALL CRAFT ADVISORIES VALID AS OF THE EARLY TUESDAY
MORNING FORECAST PACKAGE.
WEAK HIGH PRESSURE WILL REMAIN ACROSS THE AREA WEDNESDAY WHILE A LOW
PRESSURE SYSTEM TRACKS WELL SOUTH AND EAST OF THE WATERS. A COLD
FRONT WILL THEN MOVE THROUGH WEDNESDAY NIGHT. HIGH PRESSURE WILL
THEN BUILD BACK IN THURSDAY INTO FRIDAY WITH SEVERAL AREAS OF LOW
PRESSURE TO TRACK OVER OR JUST SOUTH OF THE WATERS THROUGH THE
WEEKEND.
THIS PATTERN WILL YIELD SEVERAL BOUTS OF INCREASED WINDS AND SEAS
BUT OVERALL THE CHANCES OF ADVISORY CONDITIONS APPEAR LOW AT THIS
TIME...AT LEAST THROUGH FRIDAY. THE BEST CHANCE OF SCA CONDITIONS
WILL BE IN CHARLESTON HARBOR AND ACROSS THE WATERS BEYOND 20 NM
WED...POSSIBLY LINGERING INTO THU MORNING BEYOND 20 NM. THERE WILL
BE A CHANCE OF SCA CONDITIONS OVER THE WATERS THIS
WEEKEND...ESPECIALLY BEYOND 20 NM....BUT MUCH DEPENDS ON THE TRACK
OF THE AFOREMENTIONED LOW PRESSURE SYSTEMS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS TOPEKA KS
643 AM CDT TUE MAR 19 2013
...UPDATE TO AVIATION...
.DISCUSSION...
THE LATEST WATER VAPOR LOOP THIS MORNING AT 07Z SHOWS A WAVE MOVING
INTO SOUTHEAST WYOMING MOVING SOUTHEAST. THIS FEATURE WILL BRING
SOME ASCENT INTO NORTHEAST KANSAS BY LATE MORNING THROUGH THE
AFTERNOON HOURS. FORECAST SOUNDINGS FROM RAP SHOW STEEP LAPSE RATES
BELOW 750 MB THIS AFTERNOON. SOME ELEVATED INSTABILITY IS ALSO
PRESENT AND HAVE ADDED SHOWERS FOR PARTS OF NORTH CENTRAL AND
NORTHEAST KANSAS THIS AFTERNOON. LOW LEVELS ON SOUNDINGS SHOW THE
LOWER BOUNDARY LAYER MOISTENING WITH TIME. HIGHS TODAY WILL WARM
INTO THE MID 50S ACROSS THE SOUTHERN PORTIONS OF THE CWA WHILE THE
NORTHEAST CORNER WILL BE COOLEST WITH HIGHS IN THE UPPER 40S.
TONIGHT THROUGH WEDNESDAY BRINGS A DRY PERIOD TO THE FORECAST WITH A
NORTHWEST FLOW PATTERN ALOFT. TEMPERATURES WILL BE COOLER ON
WEDNESDAY WITH HIGH PRESSURE OVER NORTH CENTRAL AND NORTHEAST
KANSAS. EXPECTING HIGHS IN THE 40S.
WARM ADVECTION AND MOISTURE RETURN BEGINS IN EARNEST ALONG WITH
ISENTROPIC LIFT IN WESTERN AND CENTRAL KANSAS. BEST MOISTURE FOR ANY
PRECIPITATION REMAINS MAINLY WEST OF HIGHWAY 81 AND HAVE ADJUSTED
POPS WEDNESDAY NIGHT FURTHER WEST AND TRIMMED FURTHER EAST.
ISENTROPIC LIFT SHIFTS FURTHER EAST THURSDAY MORNING WITH MOISTURE
ADVECTION MAXIMIZED IN THE AFTERNOON HOURS. MODELS ARE IN AGREEMENT
WITH A SHORTWAVE MOVING OUT OF THE ROCKIES AND ACROSS KANSAS
THURSDAY AND THURSDAY NIGHT. BEST FOCUS FOR PRECIPITATION WILL BE
ACROSS EAST CENTRAL KANSAS. WITH WARMER TEMPERATURE PROFILES EXPECT
MORE OF A MIX OF PRECIPITATION TYPES THURSDAY AFTERNOON WITH THE
NORTHEAST REMAINING COLD ENOUGH FOR SNOW BUT EXPECT A MIX OF
RAIN...SLEET AND SNOW ACROSS NORTH CENTRAL AND NORTHEAST KANSAS.
WENT WITH A BLEND OF THE ECMWF...GEM AND GFS THROUGH FRIDAY THEN
WITH THE ECMWF AND GEM OVER THE WEEKEND. EXPECT THAT AROUND 2 INCHES
OR LESS OF ACCUMULATION AS THE SNOW WILL BE WET WITH SNOW/WATER
RATIO OF 6 TO 1 UP TO 9 TO 1...MELTING AND SOIL TEMPERATURES IN THE
MID AND UPPER 40S.
THE ECMWF AND GEM ARE IN GOOD AGREEMENT WITH THE UPPER TROUGH AXIS
MOVING THROUGH THE PLAINS ON SATURDAY NIGHT AND SUNDAY. THEY TAKE A
FURTHER SOUTH AND EAST TRACK THAN THE GFS WITH THE MID AND UPPER
LEVEL FEATURES. DEFORMATION ZONE WILL LAY ACROSS NORTHEAST AND EAST
CENTRAL KANSAS SATURDAY NIGHT AND SUNDAY. TEMPERATURE PROFILES
SUGGEST ALL SNOW SATURDAY NIGHT WITH A MIX OF RAIN AND SNOW SOUTH OF
I-70 SUNDAY WITH SNOW NORTH AND SOME ACCUMULATING SNOW IS POSSIBLE.
MODIFIED TEMPERATURES THURSDAY NIGHT AND FRIDAY NIGHT DUE TO CLOUDS
AND LIGHT PRECIPITATION. ANOTHER UPPER TROUGH IS FORECAST TO MOVE
INTO THE ROCKIES ON TUESDAY AND MAY BRING SOME MORE WINTER TYPE
WEATHER WITH IT.
53
&&
.AVIATION...
FOR 12Z TAFS...CONDITIONS SHOULD REMAIN VFR THROUGH THE TAF PERIOD.
A WEAK WAVE WILL PASS OVER THE AREA TODAY...WHICH COULD BRING A FEW
FLURRIES OR SPRINKLES THIS MORNING ACROSS NORTHEAST KANSAS AND
POSSIBLY A FEW LIGHT RAIN SHOWERS DURING THE AFTERNOON HOURS.
HOWEVER...CONFIDENCE REMAINS LOW IN THE PROBABILITY OF ANY LIGHT
SHOWERS REACHING AS FAR SOUTH AS THE TAF SITES...SO HAVE KEPT ANY
MENTION OUT OF THE TAFS AT THIS TIME. IF ANY RAIN SHOWERS MANAGE TO
DEVELOP NEAR THE TAF SITES...CIGS COULD BRIEFLY APPROACH BORDERLINE
MVFR/VFR CONDITIONS. MID-LEVEL CLOUDS WILL BEGIN TO SCATTER OUT BY THIS
EVENING AS THE WAVE PASSES EAST OF THE AREA...WITH WINDS SHIFTING
FROM WEST TO NORTHWEST.
ACH
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
728 AM EDT TUE MAR 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 547 AM EDT TUE MAR 19 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW TROF EXTENDING FROM SCNTRL
CANADA INTO THE GREAT LAKES. SNOW IS DIMINISHING ACROSS UPPER MI AS
SHORTWAVE SLIPS E OF THE AREA. AT THE SFC...LOW PRES IS LOCATED OVER
CNTRL LAKE SUPERIOR. ON THE BACKSIDE OF THE LOW...STRONG NW WINDS
ARE DEVELOPING OVER FAR WRN LAKE SUPERIOR AND WILL BE REACHING UPPER
MI SHORTLY.
FCST THINKING HAS NOT CHANGED MUCH SINCE YESTERDAY. STRONG/GUSTY NW
WINDS WILL DEVELOP FROM W TO E TODAY AS SFC LOW PRES DRIFTS E. DEEP
MOISTURE/CONVERGENT CYCLONIC WNW FLOW AND INCREASINGLY COLDER AIR
WILL YIELD MDT/HVY LAKE ENHANCED SNOW DEVELOPING EARLY THIS MORNING
OVER THE W AND SPREADING TO AREAS FROM AROUND MUNISING EASTWARD LATE
MORNING/AFTN. WITH FCST SOUNDINGS SHOWING A DEEP DGZ OVER
GOGEBIC/ONTONAGON COUNTIES...SNOW SHOULD BE VERY HVY AT TIMES IN
THAT AREA TODAY. MEANWHILE...BEST LOW-LEVEL CONVERGENCE WILL SET UP
ACROSS NRN ONTONAGON COUNTY/SRN HALF OF HOUGHTON COUNTY FOR MUCH OF
TODAY/TONIGHT. BOTH FACTORS WILL RESULT IN GREATEST SNOW
ACCUMULATIONS TODAY/TONIGHT OCCURRING FROM THE HIGHER TERRAIN JUST N
OF KIWD TO THE PORCUPINE MOUNTAINS...ROCKLAND...TWIN LAKES AND
PAINESDALE. AMOUNTS UPWARDS OF 18 INCHES FROM 12Z TODAY-12Z WED SEEM
LIKELY IN THOSE AREAS...BUT WOULDN`T BE SURPRISED TO SEE MORE THAN
THAT. FARTHER N ON THE KEWEENAW...AMOUNTS WILL LIKELY TREND DOWN TO
A FOOT OR LESS UNDER WEAKER LOW-LEVEL CONVERGENCE. STRONG BOUNDARY
LAYER WINDS WILL SPREAD STEADIER SNOWS INTO BARAGA COUNTY WITH
ACCUMULATIONS LIKELY REACHING WARNING CRITERIA OVER HIGH TERRAIN. TO
THE E...AIR MASS WON`T BE QUITE AS COLD AND MAY RESULT IN DGZ BEING
DISPLACED A LITTLE ABOVE BEST UPWARD MOTION TODAY...BUT DGZ BECOMES
BETTER POSITIONED IN CONVECTIVE LAYER TONIGHT. LOW-LEVEL CONVERGENCE
IS NOT AS STRONG AS OVER THE W THROUGHOUT TODAY/TONIGHT. THESE
FACTORS SHOULD KEEP SNOW ACCUMULATIONS DOWN TO THE 6-12 INCH RANGE
BY WED MORNING WITH THE GREATEST AMOUNTS E OF MUNISING AND N/NW OF
KERY. WINDS WILL BE A SIGNIFICANT FACTOR. WITH GUSTS OF 30-40MPH...
ALONG LAKE SUPERIOR AND OVER THE KEWEENAW...BLSN WILL BE A MAJOR
ISSUE WITH WHITE-OUTS AT TIMES DUE TO HVY SNOW/BLSN. BLSN WILL BE
MOST SIGNIFICANT OVER THE KEWEENAW PENINSULA...WITH WORST CONDITIONS
THIS AFTN/EVENING.
AWAY FROM HEADLINE AREAS...-SN EARLY WILL TRANSITION TO SCT -SHSN.
DOWNSLOPE WWN WINDS WILL LIKELY BRING AN END TO -SHSN OVER THE
SCNTRL THIS AFTN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 547 AM EDT TUE MAR 19 2013
MODELS ADVERTISE PRETTY STRAIGHT FORWARD LARGE SCALE PATTERN FOR THE
LONG TERM PERIOD. AGREEMENT IN THE PRIMARY FEATURES IN THE LARGER
SCALE FLOW IS GOOD WHICH LEADS TO HIGHER CONFIDENCE FORECAST.
UPPER TROUGH FROM SOUTHERN QUEBEC/NEW ENGLAND WESTWARD ACROSS GREAT
LAKES IS MAIN FEATURE THROUGH LATE THIS WEEK. AS MOST OF UPPER JET
ENERGY ROUNDS BASE OF TROUGH...EXPECT TROUGH TO RAMBLE SLOWLY EAST
BY FRIDAY WHICH RESULTS IN HEIGHTS GRADUALLY RISING OVER UPPER GREAT
LAKES INTO NEXT WEEKEND. SFC PATTERN WELL AGREED UPON AS WELL. SFC
LOW STARTS OUT JUST EAST OF LK SUPERIOR ON WEDNESDAY THEN SHIFTS
INTO SOUTHERN QUEBEC BY THURSDAY WITH TROUGHING ENHANCED BY THE
LAKES LINGERING ACROSS LK SUPERIOR REGION. NO SIGNIFICANT CHANGE
TO PREVIOUS FCST THINKING THAT MODERATE TO AT TIMES HEAVY LK EFFECT
SNOWS IMPACT MAINLY NW SNOW BELTS OF LK SUPERIOR ON WEDNESDAY. DEEP
MOISTURE TIED TO TROUGH LINGERS AND SOUNDINGS ACTUALLY SHOW COLDEST
925-850MB TEMPS THROUGH WEDNESDAY. SFC-H95 CONVERGENCE PEGS HIGHER
TERRAIN OF WESTERN CWA ROUGHLY IRONWOOD-WAKEFIELD THROUGH TWIN LAKES
AND ATLANTIC MINE THOUGH STRONG BLYR WINDS OVER 30 KTS WILL PUSH
HEAVIER SNOW SHOWERS FARTHER INLAND THAN NORMALLY OCCURS WITH SIMILAR
WIND DIRECTION.
CONVERGENCE ALSO STRONG OVER EAST...ROUGHLY MUNISING TO NORTH OF
NEWBERRY. AGAIN STRONG WINDS MAY PUSH AT LEAST MODERATE SNOW SHOWERS
AS FAR SOUTH AS US-2 IN SCHOOLCRAFT COUNTY. HIGHEST SNOW AMOUNTS /UP
TO 6 INCHES IN 12 HRS/ EXPECTED ON WEDNESDAY. SHORTWAVE TROUGH DROPS
THROUGH THE OVERALL MEAN TROUGHING ON WEDNESDAY NIGHT. MODELS HAVE
BEEN SHOWING THIS AWHILE NOW. MAIN RESULT WILL BE WINDS SHIFTING TO
MORE NNW-N DIRECTION VERSUS NW WINDS SEEN THROUGH WEDNESDAY. SNOW
OVER NORTHWEST-WEST MARQUETTE COUNTY COULD AFFECT MORE OF THE COUNTY
WITH MORE NORTHERLY WINDS. SOUNDINGS DO INDICATE DECENT DRYING IN
WAKE OF THE WAVE IN H8-H7 LAYER BY LATER THURSDAY MORNING...BUT MOST
OF LAKE EFFECT CONVECTIVE LAYER IS WITHIN DGZ...SO SLR/S AROUND 20:1
WILL BOOST AMOUNTS. POSSIBLE THAT ADVY LEVEL SNOW AMOUNTS COULD
OCCUR LATER WEDNESDAY EVENING THROUGH MID MORNING THURSDAY OVER
MARQUETTE COUNTY...IMPACTING THU MORNING COMMUTE. LATER SHIFTS MAY
NEED TO CONSIDER HEADLINES FOR MARQUETTE COUNTY FOR THIS POTENTIAL.
DRYING SUBSIDENCE BEGINS TO TAKE BITE INTO LK EFFECT OVER WESTERN
CWA ON THURSDAY AFTN. LOCAL WRF PREFERRED WITH LOOK OF LK EFFECT
POPS/QPF THROUGH THURSDAY MORNING AND THIS INDICATES INVERSIONS
LOWERING TO LESS THAN 4KFT BY THURSDAY AFTN IN THE WEST. CURRENT
ENDING TIME OF 12Z THURSDAY FOR THE WEST LOOKING GOOD. SETUP A BIT
BETTER IN EAST THROUGH THURSDAY...BUT EVEN THERE...INVERSIONS LOWER
BLO 5KFT THOUGH THERE IS LINGERING MOISTURE BLO H7 INTO THURSDAY
EVENING. OVERALL...STRONG SUBSIDENCE/DRYING ABOVE INVERSION AND LACK
OF REAL COLD TEMPS WITHIN LK EFFECT MOIST LAYER POINTS TO
SIGNIFICANT DIMINISHING TREND TO LK EFFECT BY LATE THURSDAY
AFTN/EVENING.
EVEN SO...IT IS NOT UNTIL FRIDAY AND MAYBE EVEN AS LATE AS SATURDAY
BEFORE LOW-LEVEL FLOW OVER AREA BECOMES MORE ANTICYCLONIC AS HIGH
PRESSURE OVER NORTHERN CANADA EXPANDS INTO MANITOBA AND NORTHWEST
ONTARIO. NORTH WINDS OFF LK SUPERIOR AND TEMPS AROUND -8C KEEP
CLOUDS AND PERHAPS LGT FLURRIES GOING ON FRIDAY OVR NCNTRL UPR
MICHIGAN. AT SOME POINT...LK EFFECT WILL CEASE DUE TO INCREASING
LOW-LEVEL SHEAR AND SUBSIDENCE WITH CONTINUED WARMING TEMPS AT TOP
OF INVERSION. BY LATER IN THE WEEKEND LAST COUPLE RUNS OF GFS ARE
DEVELOPING WOUND UP SHORTWAVE/LOW PRESSURE SYSTEM IN THE CENTRAL
PLAINS. 12Z/18 MARCH ECMWF WAS MUCH MORE SUPPRESSED WITH SUCH A
SYSTEM RIDING IT ACROSS SOUTHERN TIER OF CONUS. 00Z ECMWF DID SHOW
MORE AMPLIFICATION BUT STILL KEEPS SYSTEM OVER SOUTHERN PORTION OF
OHIO VALLEY. GEM-NH/UKMET MORE WOUND UP NOW TOO...BUT LIKE ECMWF ARE
NOT NEAR AS NORTHWEST AS GFS. CAN NOT COMPLETELY COUNT OUT SOME SORT
OF SYSTEM AS TROUGHING IS PRESENT IN LARGE SCALE FROM WESTERN CANADA
INTO SOUTHERN PLAINS. PREFER THE LOOK OF WPC HAND DRAWN PROGS WITH
LOW TRACKING ACROSS SOUTHEAST CONUS AT THIS POINT. MAIN RESULT IS
QUIET WEATHER OVER UPR LAKES THROUGH THE UPCOMING WEEKEND WITH MORE
CLOUDS THAN SUNSHINE AND HIGH TEMPERATURES AT OR SLIGHTLY BLO NORMAL
IN THE LOW-MID 30S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 727 AM EDT TUE MAR 19 2013
AS THE LOW PRES OVER LAKE SUPERIOR DRIFTS E TODAY...STRONG NW WINDS
AND COLDER AIR WILL SPREAD ACROSS THE AREA...BRINGING MDT/HVY LAKE
ENHANCED SNOW/BLSN AND PREVAILING LIFR CONDITIONS TO KIWD/KCMX. DEEPER
MOISTURE WILL SLIP E OF KIWD FOR A TIME THIS AFTN/EVENING...SO THERE
MAY BE PERIOD OF IFR CONDITIONS THERE IN THE AFTN/EVENING. NW WINDS
SHOULD GUST TO 25-35KT AT KIWD AND ESPECIALLY AT THE MORE EXPOSED
KCMX SITE. AT KSAW...DOWNSLOPING WNW WINDS SHOULD RESULT IN MAINLY
MVFR CONDITIONS THRU THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 547 AM EDT TUE MAR 19 2013
AS LOW PRES OVER ERN LAKE SUPERIOR DRIFTS E TODAY AND TONIGHT...NW
GALES WHICH ARE CURRENTLY DEVELOPING OVER WRN LAKE SUPERIOR WILL
EXPAND E ACROSS THE LAKE TODAY. THE GALES WILL THEN CONTINUE INTO
WED OVER THE E HALF OF THE LAKE WHILE WINDS DIMINISH SLIGHTLY BELOW
GALES OVER THE W. WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO
E WED NIGHT/THU. THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES
WILL LEAD TO PERIODS OF HVY FREEZING SPRAY THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER STORM WARNING FROM 11 AM THIS MORNING TO 8 AM EDT
THURSDAY FOR MIZ006-007-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 2 PM THIS AFTERNOON TO 8 PM
EDT WEDNESDAY FOR LSZ243>245-248>251-264>267.
GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ WEDNESDAY FOR LSZ162-263-
264-266-267.
GALE WARNING FROM 2 PM THIS AFTERNOON TO 2 PM EDT WEDNESDAY FOR
LSZ243>245-249>251-265.
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY
FOR LSZ162-240>242-263.
GALE WARNING FROM 2 PM THIS AFTERNOON TO 6 AM EDT WEDNESDAY FOR
LSZ248.
GALE WARNING FROM 2 PM THIS AFTERNOON TO 11 PM EDT THIS EVENING
FOR LSZ246-247.
GALE WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
LSZ240>242.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS BILLINGS MT
905 AM MDT TUE MAR 19 2013
.SHORT TERM...VALID FOR TDY AND WED...
WEAK SHORTWAVE EMBEDDED IN AN UNSTABLE NW FLOW COMBINED WITH LOW
LEVEL FRONTOGENESIS ALONG SFC BOUNDARY AND TEMPERATURES FAVORABLE
FOR DENDRITIC GROWTH ARE ALLOWING FOR LIGHT SNOW SHOWERS/FLURRIES
TO CONTINUE IN AN AREA FROM JUDITH GAP...ROUNDUP AND BILLINGS
EAST/SOUTHWARD TO FORSYTH AND SHERIDAN. OBS/WEB CAMS SHOW JUST A
DUSTING TO LESS THAN A HALF INCH FOR MOST OF THIS AREA. CLOUD TOPS
NOT WARMING YET BUT THEY WILL SHORTLY AS SHORTWAVE ENERGY DEPARTS
AND FRONTOGENESIS WANES...PER RAP WHICH SEEMS TO HAVE A FAIR
HANDLING OF THE CURRENT SITUATION. HAVE EXPANDED SCATTERED
COVERAGE FOR THIS ACTIVITY... WHICH WILL PROBABLY PERSIST TO A
COUPLE HOURS BEYOND 18Z INTO THE AFTERNOON...BUT OTHERWISE A
DIMINISHING TREND IS ANTICIPATED THIS AFTERNOON AS HEIGHTS BEGIN
TO RISE FROM THE WEST. DOWNSLOPE WINDS AND SUN WILL ALLOW FOR
TEMPS INTO THE 40S OUT WEST...BUT LOW LEVEL NORTH TO EAST WINDS
AND POOR MIXING WILL KEEP TEMPS IN THE 30S CENTRAL AND EAST
PARTS...AND EVEN MID TO UPPER 20S ALONG THE DAKOTAS BORDER WHERE
COLD AIR ASSOCIATED WITH CANADIAN SFC RIDGE WILL BE DEEPEST.
AS FOR BILLINGS...LIGHT SNOW SHOWERS/FLURRIES WILL TAPER OFF BY
NOON BUT LIGHT TO EAST WINDS WILL KEEP TEMPS ON THE COOLISH SIDE
TODAY WITH HIGHS IN THE UPPER 30S TO NEAR 40...IE ABOUT 10
DEGREES BELOW NORMAL.
LOOK FOR A DRY NIGHT TONIGHT AS UPPER RIDGE BUILDS OVER THE
REGION. THIS WILL LEAD TO A WARMER WEDNESDAY PRIOR TO WED NITE/THU
SHORTWAVE/COLD FRONT.
JKL
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM AND LONG RANGE MODELS REMAIN IN GOOD AGREEMENT. ALL MODELS
CONTINUE TO ADVERTISE UNSETTLED WEATHER TREND FOR THURSDAY THROUGH
EARLY NEXT WEEK ALONG WITH BELOW NORMAL TEMPERATURES.
MAIN WEATHER PRODUCER WILL BE ON THURSDAY AS AN UPPER LEVEL TROUGH
OF LOW PRESSURE MOVES IN FROM THE PACIFIC NORTHWEST. LEFT EXIT
REGION OF THE JET ASSOCIATED WITH THIS TROUGH WILL BE MOVING OVER
OUR AREA ALONG WITH MODERATE QG FORCING. GOOD PACIFIC MOISTURE
FEED INDICATED BY MODELS AND THIS WILL COMBINE WITH AN INVERTED
SURFACE TROUGH TO BRING SNOW TO OUR SOUTHWEST MOUNTAINS AND AREAS
WEST OF BILLINGS THURSDAY MORNING. THIS FORCING WITH THE UPPER
TROUGH WILL SHIFT EASTWARD THROUGH THE DAY. HAVE RAISED POPS IN
THE WEST FOR THURSDAY MORNING AND ALSO ALONG THE FOOTHILLS FROM
RED LODGE TO MC LEOD AS A SHORT PERIOD OF UPSLOPE FLOW WILL TAKE
PLACE WITH THE PASSAGE OF A COLD FRONT MOVING IN FROM THE NORTH.
ALSO INCREASED POPS TO LIKELY IN OUR EASTERN ZONES WITH INVERTED
SURFACE TROUGH MOVING OVER THIS AREA.
FRIDAY INTO EARLY NEXT WEEK WILL REMAIN UNSETTLED AS A BROAD
UPPER LEVEL TROUGH WILL REAMIN OVER THE NORTHERN PLAINS. MAIN LIFT
WITH THE TROUGH WILL STAY NORTH OF OUR AREA BUT ENOUGH ENERGY FROM
WEAK IMPULSES MOVING THROUGH TO BRING SCATTERED RAIN OR SNOW
SHOWERS. TEMPERATURES WILL BE BLOW SEASONAL NORMALS AS COLDER
CANADIAN AIR WILL FILTER INTO OUR AREA. HIGH TEMPERATURES WILL BE
IN THE UPPER 30S TO LOWER 40S. DID LOWER OVERNIGHT TEMPERATURES
WITH MODELS ADVECTING COLDER AIR INTO SOUTHERN MONTANA DURING
THIS TIME PERIOD. RICHMOND
&&
.AVIATION...
ISOLATED TO SCATTERED SNOW SHOWERS CONTINUE TO IMPACT WESTERN
ROUTES...INCLUDING KBIL AND KSHR...AS WELL AS HIGH TERRAIN.
LOCALIZED REDUCED FLIGHT CONDITIONS...AS LOW AS IFR AND LIFR CIGS
AND VIS AT TIMES. MOUNTAIN OBSCURATIONS CAN BE EXPECTED THIS
MORNING WITH THE SNOW SHOWERS. PRECIPITATION SHOULD BEGIN TO CLEAR
FROM WEST TO EAST BY LATE MORNING...WITH MAINLY VFR CONDITIONS
PREVAILING THROUGH THE REMAINDER OF THE DAY. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 039 026/056 032/042 027/038 022/041 023/040 025/039
2/J 01/E 45/W 32/W 21/B 12/J 22/W
LVM 042 026/054 034/042 024/038 019/036 019/038 020/038
0/B 12/W 56/W 32/J 22/J 22/J 22/J
HDN 037 023/056 029/043 026/039 023/040 022/041 025/040
3/J 01/B 46/W 42/W 21/B 12/W 21/B
MLS 031 021/046 026/038 024/037 022/039 020/040 022/041
1/B 01/B 26/W 42/J 11/B 11/B 11/B
4BQ 033 020/047 024/039 023/036 021/037 020/039 020/040
2/J 00/B 16/W 42/J 11/B 12/W 21/B
BHK 025 014/037 019/031 019/033 017/033 016/034 017/035
1/B 00/N 16/J 43/J 11/B 11/B 11/E
SHR 034 018/052 027/039 021/034 018/036 017/036 018/034
3/J 01/B 26/W 43/J 22/J 23/J 21/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1136 AM MDT TUE MAR 19 2013
.UPDATE...
&&
.AVIATION...LATEST SURFACE ANALYSIS SHOWING PRESSURE RISES ACROSS
MUCH OF THE PLAINS AS SURFACE HIGH SLIDES ACROSS NORTHEAST
COLORADO. NOW APPEARS THAT NORTHEASTERLIES MAY HANG ON A BIT
LONGER AT AREA AIRPORTS. WILL DELAY THE NORTHWESTERLIES TILL 20Z.
&&
.PREV DISCUSSION... /ISSUED 1044 AM MDT TUE MAR 19 2013/
UPDATE...
SHORT TERM...MODERATE TO STRONG NORTHWEST FLOW ALOFT CURRENTLY
OVER THE AREA. AIRMASS FAIRLY DRY WITH HUMIDITY HEADING TOWARD
THE TEENS ACROSS THE FOOTHILLS AND PLAINS. SURFACE ANTICYCLONE IN
THE DENVER AREA AT THIS TIME. SPEEDS A BIT STRONGER THAN
ADVERTISED ALONG THE URBAN CORRIDOR...PROBABLY DUE TO ENHANCEMENT
FROM CHEYENNE RIDGE. WINDS SHOULD SHIFT TO THE NORTHWEST BY THE
AFTERNOON ONCE MIXING COMMENCES. RED FLAG WARNING FOR NORTHERN
FOOTHILLS AND PORTIONS OF URBAN CORRIDOR STILL SEEMS ON TRACK.
FURTHER EAST...STILL SOME QUESTION WHETHER HUMIDITY WILL GET TO
CRITICAL FIRE WEATHER THRESHOLDS. WILL HOLD OFF ON HOISTING AT
THIS TIME. OVERALL CURRENT FORECASTS SEEM ON TRACK FOR THIS
AFTERNOON...THOUGH MAY NEED TO ADJUST THE TIMING OF THE NORTHWEST
WINDS ALONG URBAN CORRIDOR A BIT LATER IF ANTICYCLONE PERSISTS.
AVIATION...FAIRLY STRONG ANTICYCLONE IN PLACE...WITH NORTHERLY
WINDS PERSISTING AT AREA AIRPORTS. LATEST MODELS CONTINUE TO SHOW
NORTHWESTERLIES DOMINATING BY 18Z WITH SOME GUSTS TO 25 KTS. THIS
STILL SEEMS REASONABLE ONCE MIXING OCCURS. WILL CONTINUE THE
TRENDS OF THE CURRENT TAFS FOR THE UPCOMING ISSUANCE. WINDS SHOULD
DECREASE AFTER 00Z. WEAK FRONT STILL EXPECTED TO PUSH ACROSS THE
DENVER AREA AROUND 03Z WITH LIGHT NORTHEAST OR EAST WINDS...THEN
DRAINAGE BY MIDNIGHT. WITH DRY AIRMASS...DOES NOT LOOK LIKE ANY
STRATUS WILL DEVELOP.
PREV DISCUSSION... /ISSUED 313 AM MDT TUE MAR 19 2013/
SHORT TERM...MAIN ISSUE THIS TODAY WILL BE FIRE WX POTENTIAL IN
THE NRN FOOTHILLS AND ALONG THE WY BORDER. LATEST RAP HAS
HUMIDITIES DROPPING BELOW 15% BY EARLY AFTN ALONG THE FRONT RANGE
AND IN THE NRN FOOTHILLS WITH GUSTY NWLY WINDS DEVELOPING. FIRE
WX MANAGERS INDICATE HIGH FIRE POTENTIAL IN THE NRN FOOTHILLS AND
FM NORTH OF DENVER TO THE WY BORDER. WITH THAT IN MIND WILL ISSUE
A RED FLAG WARNING NORTH OF A LINE FROM BOULDER TO DENVER UP TO
THE WY BORDER FM 18Z-00Z.
OTHERWISE THE FLOW ALOFT WILL REMAIN WNW WITH SOME HIGHER LEVEL
MOISTURE MOVING ACROSS PRODUCING SOME HI LVL CLOUD COVER. AT THE
SFC A COOL FNT WILL MOVE ACROSS THE FAR NERN PLAINS WHICH WILL
BRING IN SOME SLIGHTLY COOLER AIR. THUS WILL KEEP HIGHS IN THE
UPPER 40S OVER THE FAR NERN PLAINS WITH LOWER 50S ALONG THE FRONT
RANGE URBAN CORRIDOR. FOR TONIGHT OUTSIDE OF SOME MID AND HIGH
LEVEL CLOUDS IT WILL BE DRY. WINDS SHOULD DIE DOWN BY SUNSET WITH
AN INCREASE IN HUMIDITY LEVELS WHICH WILL DECREASE FIRE DANGER.
LONG TERM...A PROGRESSIVE PATTERN THROUGH LATE WEEK AS WEDNESDAY
WILL SEE THE RIDGE ALOFT FLATTEN AS IT MOVES OVER COLORADO AND
ADJACENT REGIONS. WEDNESDAY SHOULD BE THE WARMEST DAY OF THE WEEK
AND RELATIVELY DRY WITH LESS WIND. HOWEVER...MOISTURE WILL BE
QUICKLY SPREADING INTO THE MOUNTAINS LATE WEDNESDAY AFTERNOON IN
ADVANCE OF NEXT WEAK WAVE IN THE NORTHWEST FLOW PATTERN. EXPECT
THE MOUNTAINS TO BENEFIT THE MOST WITH DECENT OROGRAPHIC FLOW AND
MODEST LAPSE RATES. THE UPPER LEVEL TROF WILL MOVE ACROSS COLORADO
ON THURSDAY WITH ASSOCIATED COLD FRONT ACROSS NORTHEAST COLORADO
LATE THURSDAY AFTERNOON WITH SCATTERED SHOWERS. SURFACE WIND IS
MAINLY DOWNSLOPE NORTHWEST WIND BUT ENOUGH INSTABILITY FOR
SCATTERED SHOWERS TO GENERATE.
THE MAIN QUESTION IN THE LONG TERM CONCERNS THE NEXT BIGGER UPPER
LOW WHICH IS FORECAST TO DEVELOP OVER WESTERN COLORADO EARLY
SATURDAY MORNING BEFORE MOVING INTO THE TEXAS PANHANDLE BY LATE
SATURDAY NIGHT. THE LONG RANGE MODELS HAVE SHOWN MORE CONSISTENCY
WITH THIS SCENARIO WHICH HAD BEEN A BIG CHANGE FROM THE MODEL
RUNS SEVERAL DAYS AGO. RIGHT NOW THE EUROPEAN AND CANADIAN RUNS
ARE SHOWING THE DEEPEST LOW NEAR THE 4 CORNERS WHILE THE GFS IS A
BIT MORE PROGRESSIVE AND MORE OF AN OPEN WAVE ACROSS COLORADO. IF
THE EUROPEAN AND FRIENDS VERIFY...IT COULD MEAN A POTENTIAL FOR
HEAVY SNOW ON SATURDAY OVER THE EAST SLOPES AND NORTHEAST PLAINS.
STILL A WAYS TO GO AS WOULD EXPECT FUTURE MODEL CORRECTIONS AS WE
GET CLOSER TO THE EVENT. CERTAINLY SOME POTENTIAL AND MAJOR
IMPACTS IF IT VERIFIES. WON`T CHANGE MUCH TO CURRENT ZONES WITH
CHANCE OF SNOW OVER ENTIRE AREA THROUGH EARLY IN THE WEEKEND. IF
CONSISTENCY CONTINUES WILL LIKELY INCREASE POPS IN LATER SHIFTS.
AVIATION...WINDS EARLY THIS MORNING HAVE BEEN WNW AROUND 10 KTS.
WITH NWLY LOW LVL FLOW OVER THE CHEYENNE RIDGE MAY SEE A LONGMONT
ANTI CYCLONE THRU LATE MORNING WITH WINDS BECOMING MORE NLY BY
15Z THRU MIDDAY. BY EARLY AFTN THE STRONGER FLOW ALOFT MAY MIX
DOWN TO THE SFC ALLOW FOR GUSTY NWLY WINDS TO DVLP WITH SPEEDS IN
THE 15-20 MPH RANGE WITH A FEW GUSTS TO 25 MPH. BY 00Z IT APPEARS
WINDS SHOULD DECREASE BACK TO 10-15 MPH. DURING THE EVENING A WK
FNT IS FCST TO BACKDOOR INTO THE AREA WITH WINDS BECOMING LIGHT
ELY WHICH GRADUALLY BECOME DRAINAGE AFTER MIDNIGHT. THERE IS VERY
LITTLE MOISTURE WITH THIS FNT SO DO NOT EXPECT ANY STRATUS
OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING FOR COZ215-238-239-
243.
&&
$$
SHORT TERM...D-L
LONG TERM....ENTREKIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1044 AM MDT TUE MAR 19 2013
.UPDATE...
&&
.SHORT TERM...MODERATE TO STRONG NORTHWEST FLOW ALOFT CURRENTLY
OVER THE AREA. AIRMASS FAIRLY DRY WITH HUMIDITY HEADING TOWARD
THE TEENS ACROSS THE FOOTHILLS AND PLAINS. SURFACE ANTICYCLONE IN
THE DENVER AREA AT THIS TIME. SPEEDS A BIT STRONGER THAN
ADVERTISED ALONG THE URBAN CORRIDOR...PROBABLY DUE TO ENHANCEMENT
FROM CHEYENNE RIDGE. WINDS SHOULD SHIFT TO THE NORTHWEST BY THE
AFTERNOON ONCE MIXING COMMENCES. RED FLAG WARNING FOR NORTHERN
FOOTHILLS AND PORTIONS OF URBAN CORRIDOR STILL SEEMS ON TRACK.
FURTHER EAST...STILL SOME QUESTION WHETHER HUMIDITY WILL GET TO
CRITICAL FIRE WEATHER THRESHOLDS. WILL HOLD OFF ON HOISTING AT
THIS TIME. OVERALL CURRENT FORECASTS SEEM ON TRACK FOR THIS
AFTERNOON...THOUGH MAY NEED TO ADJUST THE TIMING OF THE NORTHWEST
WINDS ALONG URBAN CORRIDOR A BIT LATER IF ANTICYCLONE PERSISTS.
.AVIATION...FAIRLY STRONG ANTICYCLONE IN PLACE...WITH NORTHERLY
WINDS PERSISTING AT AREA AIRPORTS. LATEST MODELS CONTINUE TO SHOW
NORTHWESTERLIES DOMINATING BY 18Z WITH SOME GUSTS TO 25 KTS. THIS
STILL SEEMS REASONABLE ONCE MIXING OCCURS. WILL CONTINUE THE
TRENDS OF THE CURRENT TAFS FOR THE UPCOMING ISSUANCE. WINDS SHOULD
DECREASE AFTER 00Z. WEAK FRONT STILL EXPECTED TO PUSH ACROSS THE
DENVER AREA AROUND 03Z WITH LIGHT NORTHEAST OR EAST WINDS...THEN
DRAINAGE BY MIDNIGHT. WITH DRY AIRMASS...DOES NOT LOOK LIKE ANY
STRATUS WILL DEVELOP.
&&
.PREV DISCUSSION... /ISSUED 313 AM MDT TUE MAR 19 2013/
SHORT TERM...MAIN ISSUE THIS TODAY WILL BE FIRE WX POTENTIAL IN
THE NRN FOOTHILLS AND ALONG THE WY BORDER. LATEST RAP HAS
HUMIDITIES DROPPING BELOW 15% BY EARLY AFTN ALONG THE FRONT RANGE
AND IN THE NRN FOOTHILLS WITH GUSTY NWLY WINDS DEVELOPING. FIRE
WX MANAGERS INDICATE HIGH FIRE POTENTIAL IN THE NRN FOOTHILLS AND
FM NORTH OF DENVER TO THE WY BORDER. WITH THAT IN MIND WILL ISSUE
A RED FLAG WARNING NORTH OF A LINE FROM BOULDER TO DENVER UP TO
THE WY BORDER FM 18Z-00Z.
OTHERWISE THE FLOW ALOFT WILL REMAIN WNW WITH SOME HIGHER LEVEL
MOISTURE MOVING ACROSS PRODUCING SOME HI LVL CLOUD COVER. AT THE
SFC A COOL FNT WILL MOVE ACROSS THE FAR NERN PLAINS WHICH WILL
BRING IN SOME SLIGHTLY COOLER AIR. THUS WILL KEEP HIGHS IN THE
UPPER 40S OVER THE FAR NERN PLAINS WITH LOWER 50S ALONG THE FRONT
RANGE URBAN CORRIDOR. FOR TONIGHT OUTSIDE OF SOME MID AND HIGH
LEVEL CLOUDS IT WILL BE DRY. WINDS SHOULD DIE DOWN BY SUNSET WITH
AN INCREASE IN HUMIDITY LEVELS WHICH WILL DECREASE FIRE DANGER.
LONG TERM...A PROGRESSIVE PATTERN THROUGH LATE WEEK AS WEDNESDAY
WILL SEE THE RIDGE ALOFT FLATTEN AS IT MOVES OVER COLORADO AND
ADJACENT REGIONS. WEDNESDAY SHOULD BE THE WARMEST DAY OF THE WEEK
AND RELATIVELY DRY WITH LESS WIND. HOWEVER...MOISTURE WILL BE
QUICKLY SPREADING INTO THE MOUNTAINS LATE WEDNESDAY AFTERNOON IN
ADVANCE OF NEXT WEAK WAVE IN THE NORTHWEST FLOW PATTERN. EXPECT
THE MOUNTAINS TO BENEFIT THE MOST WITH DECENT OROGRAPHIC FLOW AND
MODEST LAPSE RATES. THE UPPER LEVEL TROF WILL MOVE ACROSS COLORADO
ON THURSDAY WITH ASSOCIATED COLD FRONT ACROSS NORTHEAST COLORADO
LATE THURSDAY AFTERNOON WITH SCATTERED SHOWERS. SURFACE WIND IS
MAINLY DOWNSLOPE NORTHWEST WIND BUT ENOUGH INSTABILITY FOR
SCATTERED SHOWERS TO GENERATE.
THE MAIN QUESTION IN THE LONG TERM CONCERNS THE NEXT BIGGER UPPER
LOW WHICH IS FORECAST TO DEVELOP OVER WESTERN COLORADO EARLY
SATURDAY MORNING BEFORE MOVING INTO THE TEXAS PANHANDLE BY LATE
SATURDAY NIGHT. THE LONG RANGE MODELS HAVE SHOWN MORE CONSISTENCY
WITH THIS SCENARIO WHICH HAD BEEN A BIG CHANGE FROM THE MODEL
RUNS SEVERAL DAYS AGO. RIGHT NOW THE EUROPEAN AND CANADIAN RUNS
ARE SHOWING THE DEEPEST LOW NEAR THE 4 CORNERS WHILE THE GFS IS A
BIT MORE PROGRESSIVE AND MORE OF AN OPEN WAVE ACROSS COLORADO. IF
THE EUROPEAN AND FRIENDS VERIFY...IT COULD MEAN A POTENTIAL FOR
HEAVY SNOW ON SATURDAY OVER THE EAST SLOPES AND NORTHEAST PLAINS.
STILL A WAYS TO GO AS WOULD EXPECT FUTURE MODEL CORRECTIONS AS WE
GET CLOSER TO THE EVENT. CERTAINLY SOME POTENTIAL AND MAJOR
IMPACTS IF IT VERIFIES. WON`T CHANGE MUCH TO CURRENT ZONES WITH
CHANCE OF SNOW OVER ENTIRE AREA THROUGH EARLY IN THE WEEKEND. IF
CONSISTENCY CONTINUES WILL LIKELY INCREASE POPS IN LATER SHIFTS.
AVIATION...WINDS EARLY THIS MORNING HAVE BEEN WNW AROUND 10 KTS.
WITH NWLY LOW LVL FLOW OVER THE CHEYENNE RIDGE MAY SEE A LONGMONT
ANTI CYCLONE THRU LATE MORNING WITH WINDS BECOMING MORE NLY BY
15Z THRU MIDDAY. BY EARLY AFTN THE STRONGER FLOW ALOFT MAY MIX
DOWN TO THE SFC ALLOW FOR GUSTY NWLY WINDS TO DVLP WITH SPEEDS IN
THE 15-20 MPH RANGE WITH A FEW GUSTS TO 25 MPH. BY 00Z IT APPEARS
WINDS SHOULD DECREASE BACK TO 10-15 MPH. DURING THE EVENING A WK
FNT IS FCST TO BACKDOOR INTO THE AREA WITH WINDS BECOMING LIGHT
ELY WHICH GRADUALLY BECOME DRAINAGE AFTER MIDNIGHT. THERE IS VERY
LITTLE MOISTURE WITH THIS FNT SO DO NOT EXPECT ANY STRATUS
OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING FOR COZ215-238-239-
243.
&&
$$
SHORT TERM...D-L
LONG TERM....ENTREKIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1207 PM EDT TUE MAR 19 2013
.SYNOPSIS...
LOW PRESSURE EAST OF NEW JERSEY THIS MORNING WILL CONTINUE TO
DEEPEN WHILE MOVING TOWARD NEW ENGLAND BY TONIGHT. A RIDGE OF HIGH
PRESSURE WILL MOVE IN WEDNESDAY BEFORE A COLD FRONT CROSSES THE
AREA DURING THE AFTERNOON. AN AREA OF LOW PRESSURE WILL FORM ALONG
THE FRONT WEDNESDAY NIGHT AND MOVE OUT INTO THE ATLANTIC THURSDAY.
EXTENSIVE HIGH PRESSURE CENTERED IN NORTHERN CANADA WILL DOMINATE
MUCH OF NORTH AMERICA FRIDAY AND SATURDAY. LOW PRESSURE DEVELOPING
ALONG THE GULF COAST NEXT WEEKEND WILL NEED TO BE MONITORED FOR A
POSSIBLE TURN UP THE COAST EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
STILL EXPECTING WLY FLOW WILL INCREASE AND CLEARING WILL TAKE PLACE FM
WEST TO EAST AS AN UPPER IMPLS MOVES PAST THE AREA. GUSTY W WIND
THIS AFTN 25-30 MPH AND POSSIBLY THE MILDEST DAY OF THE WEEK AND
PROBABLY THE MILDEST SINCE THE 15TH. NEAR NORMAL TEMPS EXPECTED, THOUGH DID
LOWER TEMPS A FEW DEGREES BASED ON 16Z METAR OBS. STILL THINK
CLEARING LATER TODAY WILL ALLOW FOR WARMING DEWPOINTS ALSO RAISED A BIT
ACROSS THE SOUTH.
STG NEG TILT TROUGH ROLLING THRU PA AND NJ LATE TODAY AND PER SPC WRF
HAVE A CHANCE OF LATE AFTN/EVE SHOWERS FM W TO E ACROSS PA.
PROBABLY OCCURS IN SHORT N-S LINES.
OTRW THE FCST WAS BLENDED 00Z/19 NCEP MOS WITH A LEAN COLDER IN YDYS
SNOW ACCUM AREA N OF I78.
OUR PUBLIC INFO STATEMENT ON SNOWFALL WAS UPDATED AT 900 AM AND
THIS SHOULD BE THE FINAL STATEMENT FOR THIS EVENT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
TONIGHT...CLEAR TO PC WITH GUSTY WNW WINDS DIMINISHING A BIT.
THE FCST WAS BASED ON BLENDED 00Z/19 NCEP MOS GUIDANCE. A FEW
FLURRIES POSSIBLE IN THE POCONOS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
ONE MINOR SYSTEM AND THE POTENTIAL FOR A MORE SIGNIFICANT SYSTEM
AWAIT US IN THE LONG TERM PART OF THE FORECAST. THE UPPER TROUGH
ACROSS THE NORTHEAST AT THE BEGINNING OF THE PERIOD MOVES AWAY
THIS WEEKEND...BEFORE ANOTHER PROGRESSIVE H5 LOW FROM THE PLAINS
MOVES TOWARD THE REGION EARLY NEXT WEEK. TEMPERATURES WILL REMAIN
BELOW NORMAL THROUGH THE PERIOD WITH SOME MODERATION POSSIBLE
EARLY NEXT WEEK.
WEDNESDAY...THE UPPER LOW TO THE NORTH WILL BE SENDING AN UPPER
TROUGH ACROSS THE AREA WEDNESDAY ACCOMPANIED BY A MOSTLY DRY SFC
COLD FRONT. WE KEPT POPS BELOW SLGT CHC FOR NOW WITH A MOSTLY DRY
AIR MASS IN PLACE.
WED NIGHT INTO EARLY THU...WEAK LOW PRESSURE IS SHOWN DEVELOPING
ON THE COLD FRONT...WHICH WILL BE SOUTH OF THE AREA AT THIS
TIME...AND MOVING OFFSHORE LATE WED NIGHT. THERE IS THE CHC FOR
SOME SNOW LATE WED NIGHT INTO THU FOR DE/ERN NJ ASSOCIATED WITH
THIS LOW. WE KEPT THE POPS IN THE CHC RANGE FOR NOW AND PAINTED IN
SOME 0.5 - 1.0 INCH SNOW ACCUMS POSSIBLE. LOW CONFID IN THE TRACK
PRECIP FCST WITH THIS LOW.
THU INTO SUN... A MOSTLY DRY PERIOD IS EXPECTED WITH THE UPPER LOW
MOVING AWAY AND A SFC HIGH PRESSURE SYSTEM FROM CANADA EXTENDING
ITS INFLUENCE ACROSS THE AREA. SNOW SHOWERS ARE POSSIBLE ACROSS
THE SRN POCONOS...BUT ONLY SLGT CHCS ARE IN THE GRIDS ATTM.
SUN NIGHT INTO MONDAY...A PROGRESSIVE UPPER/SFC LOW IS SHOWN
MOVING ACROSS FROM THE SRN PLAINS INTO THE THE TENN VALLEY BY MON
MORNING. THE SYSTEM CONTINUES EASTWARD AND A SECOND LOW IS SHOWN
FORMING ALONG THE EAST COAST. THE 00Z EC MODEL BRINGS QPF ACROSS
THE SRN HALF OF THE FCST AREA MONDAY WITH THIS FEATURE. WE HAVE
CHC POPS IN THE GRIDS FOR NOW. THIS WILL BE THE SYSTEM TO WATCH
OVER THE NEXT SEVERAL DAYS.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TODAY...IFR CONDS IN RAIN/DRIZZLE FOG WITH POSSIBLE LIFR CONDS IN
SPOTTY DENSE FOG THROUGH ABOUT 16 OR 17Z. THIS IS A LITTLE LATER
THAN PREVIOUS THINKING BUT IS SUPPORTED BY THE LATEST RAP MODEL
GUIDANCE.
WIND TURNS W DURING EARLY TO MID AFTERNOON AND INCREASES WITH
AFTN GUSTS TO 25 OR 30 KTS AND CONDS BECOMING VFR SCT-BKN AOA 3500
FT DURING MIDDAY. CHANCE OF BRIEF MVFR CONDS IN A LATE AFTN SHOWER
ASSOCIATED WITH A STRONG NEG TILT VORT MAX CROSSING PA AND NJ.
TONIGHT...VFR SCT CLDS AOA 5000 FT WITH CHANCE OF FLURRIES AND
BRIEF MVFR CONDS IN THE POCONOS. GUSTY WNW WIND TO 20 TO 25 KTS
DIMINISH LATE.
OUTLOOK...
WED...MOSTLY VFR EXPECTED WITH GUSTY WEST WINDS.
WED NIGHT INTO EARLY THU...VFR WEST. CLOUDS AND POSSIBLE MVFR IN
LIGHT SNOW ACROSS ERN NJ AND SRN/ERN DE.
THU THRU SAT...MOSTLY VFR. A FEW SNOW SHOWERS POSSIBLE ACROSS THE
SRN POCONOS.
&&
.MARINE...
FROM SANDY HOOK TO 44065...ISSUED SCA FOR THE DAY AND CONT GLW
THERE TONIGHT. OTRW SCA ON ALL THE REMAINING ATLC WATERS THROUGH
WED.
WE MAY NEED TO UPGRADE TO A GLW TONIGHT ALONG PORTIONS OF THE ATLC
WATERS....ESP VCNTY ENTRANCE TO DE BAY DOWN TO 44009 NEAR 06Z.
MIXED MODEL SIGNALS ON WHERE THE BEST TRANSFER WILL OCCUR. NOT
ENOUGH MODEL SUPPORT TO GO WIDESPREAD ON A GALE IN THIS EARLY
MORNING FCST PACKAGE.
THE GLW VERIFICATION IN ANZ450 WAS FROM SANDY HOOK TO 44065 FROM
ROUGHLY 22Z YDY THROUGH 08Z THIS MORNING WITH A PEAK GUST OF 41 KT
AT 44065 AND MULTIPLE 37 KT AT SHOOK...ON THE NRN FRINGE OF ANZ
450.
OUTLOOK...
SCA CONDITIONS WITH GUSTY WEST TO NORTHWEST WINDS WED INTO
THU...THEN SUB-SCA CONDITIONS INTO THE WEEKEND. POTENTIAL FOR A
MORE SIGNIFICANT MARINE STORM EARLY NEXT WEEK.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT WEDNESDAY FOR ANZ451>455.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ450.
GALE WARNING FROM 6 PM THIS EVENING TO 4 AM EDT WEDNESDAY FOR
ANZ450.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ430-431.
&&
$$
SYNOPSIS...O`HARA
NEAR TERM...AMC/GAINES
SHORT TERM...DRAG
LONG TERM...O`HARA
AVIATION...AMC/O`HARA
MARINE...DRAG/O`HARA
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1236 PM CDT TUE MAR 19 2013
...UPDATE TO AVIATION...
.DISCUSSION...
THE LATEST WATER VAPOR LOOP THIS MORNING AT 07Z SHOWS A WAVE MOVING
INTO SOUTHEAST WYOMING MOVING SOUTHEAST. THIS FEATURE WILL BRING
SOME ASCENT INTO NORTHEAST KANSAS BY LATE MORNING THROUGH THE
AFTERNOON HOURS. FORECAST SOUNDINGS FROM RAP SHOW STEEP LAPSE RATES
BELOW 750 MB THIS AFTERNOON. SOME ELEVATED INSTABILITY IS ALSO
PRESENT AND HAVE ADDED SHOWERS FOR PARTS OF NORTH CENTRAL AND
NORTHEAST KANSAS THIS AFTERNOON. LOW LEVELS ON SOUNDINGS SHOW THE
LOWER BOUNDARY LAYER MOISTENING WITH TIME. HIGHS TODAY WILL WARM
INTO THE MID 50S ACROSS THE SOUTHERN PORTIONS OF THE CWA WHILE THE
NORTHEAST CORNER WILL BE COOLEST WITH HIGHS IN THE UPPER 40S.
TONIGHT THROUGH WEDNESDAY BRINGS A DRY PERIOD TO THE FORECAST WITH A
NORTHWEST FLOW PATTERN ALOFT. TEMPERATURES WILL BE COOLER ON
WEDNESDAY WITH HIGH PRESSURE OVER NORTH CENTRAL AND NORTHEAST
KANSAS. EXPECTING HIGHS IN THE 40S.
WARM ADVECTION AND MOISTURE RETURN BEGINS IN EARNEST ALONG WITH
ISENTROPIC LIFT IN WESTERN AND CENTRAL KANSAS. BEST MOISTURE FOR ANY
PRECIPITATION REMAINS MAINLY WEST OF HIGHWAY 81 AND HAVE ADJUSTED
POPS WEDNESDAY NIGHT FURTHER WEST AND TRIMMED FURTHER EAST.
ISENTROPIC LIFT SHIFTS FURTHER EAST THURSDAY MORNING WITH MOISTURE
ADVECTION MAXIMIZED IN THE AFTERNOON HOURS. MODELS ARE IN AGREEMENT
WITH A SHORTWAVE MOVING OUT OF THE ROCKIES AND ACROSS KANSAS
THURSDAY AND THURSDAY NIGHT. BEST FOCUS FOR PRECIPITATION WILL BE
ACROSS EAST CENTRAL KANSAS. WITH WARMER TEMPERATURE PROFILES EXPECT
MORE OF A MIX OF PRECIPITATION TYPES THURSDAY AFTERNOON WITH THE
NORTHEAST REMAINING COLD ENOUGH FOR SNOW BUT EXPECT A MIX OF
RAIN...SLEET AND SNOW ACROSS NORTH CENTRAL AND NORTHEAST KANSAS.
WENT WITH A BLEND OF THE ECMWF...GEM AND GFS THROUGH FRIDAY THEN
WITH THE ECMWF AND GEM OVER THE WEEKEND. EXPECT THAT AROUND 2 INCHES
OR LESS OF ACCUMULATION AS THE SNOW WILL BE WET WITH SNOW/WATER
RATIO OF 6 TO 1 UP TO 9 TO 1...MELTING AND SOIL TEMPERATURES IN THE
MID AND UPPER 40S.
THE ECMWF AND GEM ARE IN GOOD AGREEMENT WITH THE UPPER TROUGH AXIS
MOVING THROUGH THE PLAINS ON SATURDAY NIGHT AND SUNDAY. THEY TAKE A
FURTHER SOUTH AND EAST TRACK THAN THE GFS WITH THE MID AND UPPER
LEVEL FEATURES. DEFORMATION ZONE WILL LAY ACROSS NORTHEAST AND EAST
CENTRAL KANSAS SATURDAY NIGHT AND SUNDAY. TEMPERATURE PROFILES
SUGGEST ALL SNOW SATURDAY NIGHT WITH A MIX OF RAIN AND SNOW SOUTH OF
I-70 SUNDAY WITH SNOW NORTH AND SOME ACCUMULATING SNOW IS POSSIBLE.
MODIFIED TEMPERATURES THURSDAY NIGHT AND FRIDAY NIGHT DUE TO CLOUDS
AND LIGHT PRECIPITATION. ANOTHER UPPER TROUGH IS FORECAST TO MOVE
INTO THE ROCKIES ON TUESDAY AND MAY BRING SOME MORE WINTER TYPE
WEATHER WITH IT.
53
&&
.AVIATION...
BAND OF LIGHT TO MODERATE SNOW HAS SET UP ACROSS THE TOPEKA AND
MANHATTAN TERMINALS. EXPECT THIS SNOW TO PERSIST THROUGH AT LEAST
22Z. EXPECT A GRADUAL DISSIPATION OF THE SNOW LATER THIS
EVENING...HOWEVER IN THE MEAN TIME IFR CIGS AND VIS WILL BE LIKELY
THROUGH AROUND 21Z TO 22Z. AFTER 00Z CONDITIONS SHOULD IMPROVE
BACK TO VFR FOR REMAINDER OF THE TAF PERIOD.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
416 PM EDT TUE MAR 19 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP CLOSED LO
CENTERED OVER ERN LK SUP DOWNSTREAM OF RDG ALONG THE W COAST. DEEP
CYC NW FLOW OF COLD AIR ARND THE SFC LO NEAR WAWA ONTARIO IS
DOMINATING THE CWA...CAUSING LES OVER MAINLY THE WRN ZNS EARLY THIS
AFTN AS -16C H85 TEMPS SHOWN AT INL AT 12Z MOVE OVER THE LAKE. WITH
SHARPENING PRES GRADIENT BTWN PRES RISE CENTER OVER NRN MN AND PRES
FALLS OVER SE ONTARIO TO THE E OF THE SFC LO...THE NW WINDS ARE
STRENGTHENING...WITH WIND GUSTS UP TO 40 MPH REPORTED CAUSING
EXTENSIVE BLSN. THE SN HAS TAPERED OFF OVER THE FAR W AND SCENTRAL
WITH THE ADVECTION OF DRIER AIR OBSVD IN MN AT 12Z/WELL DEPICTED ON
THE 12Z MPX RAOB AND DOWNSLOPE FLOW INTO THE SCENTRAL. PUBLIC
REPORTS INDICATE AS MUCH AS 18 INCHES OF SN HAS FALLEN OVER THE HIER
TERRAIN OF THE W. FARTHER UPSTREAM...ANOTHER SHRTWV IS DIGGING SEWD
THRU LK WINNIPEG.
MAIN FCST CONCERNS THRU WED REMAIN LES/WIND TRENDS AND GOING
HEADLINES AS CLOSED LO DRIFTS ONLY SLOWLY TO THE ENE THRU SE CANADA.
LATE TODAY/TNGT...OVERALL DEEP CYC NW FLOW ARND SLOWLY DEPARTING LO
IS PROGGED TO LINGER AND CAUSE PERSISTENT LES IN THE NW WIND SN
BELTS. THE LES INTENSITY OVER THE FAR W...ESPECIALLY WHERE THE FETCH
ACRS THE OPEN WATER IS SHORTER NEAR IWD...HAS DIMINISHED AS DRIER
AIR IN MN SLID EWD. THIS DRY AIR WL IMPACT MAINLY THE AREAS NEAR THE
WI BORDER. SO THE SCENTRAL SHOULD REMAIN DRY WITH DOWNSLOPING DRIER
FLOW. BUT LATER TNGT...SHRTWV NOW NEAR LK WINNIPEG IS FCST TO DIG
SEWD...CAUSING THE LLVL FLOW TO VEER A BIT AND BRING BACK A RETURN
OF DEEPER MSTR OVER THE ENTIRE CWA ON THE CYC SIDE OF ITS TRACK.
THESE TRENDS SHOULD CAUSE LES TO PICK UP AGAIN AT IWD FOLLOWING A
BREAK THIS EVNG. IN THE NW WIND SN BELTS E OF MQT...THE ARRIVAL OF
COLDER AIR WL LIKELY ENHANCE THE INTENSITY OF THE LES THRU THE NGT
WITH FVRBL WNW LLVL FLOW SHIFTING NW. ANOTHER FACTOR FAVORING HEAVY
SN IS FVRBL ALIGNMENT OF FCST UVV MAX WITHIN THE DGZ EVEN IF STRONG
WINDS THAT CAUSE A BREAK UP OF THE DENDRITES ACT TO REDUCE THE
SN/WATER RATIOS A BIT. BUT THESE STRONG WINDS WL CAUSE EXTENSIVE
BLSN/REDUCED VSBY ESPECIALLY NEAR LK SUP...EVEN WHEN THE LES IS NOT
FALLING HEAVILY.
WED...AS THE CLOSED LO SLOWLY DRIFTS TO THE E...CYC NW FLOW IS
PROGGED TO VEER SLOWLY TO THE NNW. WITH THE ARRIVAL OF SOMEWHAT
WARMER ATLANTIC AIR FM THE NE ARND INTENSE LO PER THE 12Z GFS AND
ESPECIALLY THE NAM...DEEP MSTR IS FCST TO LINGER. ALTHOUGH THE
WARMING WITH H85 TEMPS PROGGED TO RISE TOWARD -10C OVER FAR ERN LK
SUP MIGHT TEND TO REDUCE LES INTENSITY...THE ARRIVAL OF SOME LARGER
SCALE QVECTOR CNVGC/MAINTENANCE OF DEEPER MSTR ASSOCIATED SOME
ISENTROPIC ASCENT WL RETAIN A LK ENHANCED COMPONENT. ALTHOUGH THE
BEST CHC FOR CONTINUED DRY WX WL BE OVER THE SCENTRL...FCST SDNGS
INDICATE THE MSTR WL BE DEEP ENUF TO SUPPORT AT LEAST SCT -SHSN.
SOME OF THE GUIDANCE SUGGESTS SOME DRIER AIR MAY ARRIVE OVER THE W
ON WED AFTN... BUT SLOW MOTION OF THE CLOSED LO TO THE E FAVORS THE
MODELS THAT SHOW A SLOWER EWD PROGRESSION OF THIS DRYING.
GOING HEADLINES LOOK TO BE IN GOOD SHAPE AS LONG DURATION EVENT WL
ADD TO SN ACCUMS THAT HAVE ALREADY HIT WARNING TOTALS IN MOST AREAS
WHERE THESE HEADLINES HAVE BEEN IN EFFECT. EXPECT STORM TOTAL SN TO
REACH 24 INCHES OR MORE OVER THE HIER TERRAIN OF THE W.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
LOOK FOR A SLOW AND STEADY RISE IN TEMPERATURES THROUGH THE PERIOD
AS WE SLOWLY LOSE THE INFLUENCE OF THE NEARBY 500MB TROUGH.
THE ELONGATED 500MB TROUGH WILL EXTEND FROM JUST NE OF MAINE TO
LOWER MI...AND SOUTHERN UPPER PORTIONS OF UPPER MI AT 00Z
THURSDAY...WITH A SIZABLE RIDGE STRETCHING ACROSS WYOMING AND THE
WESTERN DAKOTAS UP THROUGH SASKATCHEWAN.
WHILE THE 500MB RIDGE WILL PUSH INTO WESTERN UPPER MI/LAKE SUPERIOR
FRIDAY...IT WILL TAKE UNTIL FRIDAY NIGHT UNTIL THE NEARLY STEADY
STATE LOW OVER THE EAST PUSHES OFFSHORE. THE 19/00Z RUNS OF THE
ECMWF AND CANADIAN HOLD ONTO THE TROUGH ACROSS EASTERN UPPER MI A
BIT LONGER THAN THE GFS /BY ROUGHLY 6HRS/. THE SFC TROUGH WILL
LIKELY LINGER ACROSS EASTERN MICHIGAN THROUGH 12Z FRIDAY. THE RESULT
WILL BE CONTINUED LAKE EFFECT SNOW SHOWERS FOR NORTHERLY-NNW WIND
FAVORED LOCATIONS NEAR LAKE SUPERIOR. 850MB TEMPS WILL MODERATE FROM
THE -12 TO -15C AT 00Z THURSDAY TO AROUND -8C BY DAYBREAK FRIDAY.
EXPECT QUICKLY DIMINISHING LAKE EFFECT SNOW SHOWERS AFTER THURSDAY
AFTERNOON...WITH LOWERING INVERSION HEIGHTS
500MB RIDGING WILL BE THE RULE FRIDAY NIGHT THROUGH AT LEAST
SATURDAY NIGHT.
LOOK FOR A CLUSTERED AREA OF LOW PRESSURE CENTERED NEAR MONTANA AT
00Z SATURDAY WILL DIVIDE FRIDAY NIGHT...WITH THE NORTHERN LOW
SPINNING IN PLACE...AND THE SOUTHERN EXTENT OF THE TROUGH DIVING
ACROSS TEXAS AND OKLAHOMA BY LATE SATURDAY AFTERNOON/SATURDAY NIGHT.
THE 00Z RUNS OF THE GFS AND ECMWF WERE FAIRLY CONSISTENT WITH THE
TRACK OF THE SOUTHERN TROUGH...MOVING IT OVER KENTUCKY AND WEST
VIRGINIA BY DAYBREAK MONDAY...WITH THE RIDGE WEAKENING BUT STILL
REMAINING OVER LAKE SUPERIOR AND UPPER MICHIGAN THROUGH AT LEAST
SUNDAY NIGHT. THE 12Z GFS CAME IN WITH THE 500MB LOW SHIFTED APPROX
250MI TO THE NORTHWEST OF THE 00Z RUN TRACK...WHICH WOULD BRING IT
ACROSS LOWER MI AT 00Z TUESDAY. THIS WOULD RESULT IN STRONGER WINDS
FOR CENTRAL AND EASTERN AREAS...AS WELL AS UPSLOPE LES NORTH CENTRAL
WITH SYNOPTIC SNOW HUGGING THE EASTERN COUNTIES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 126 PM EDT TUE MAR 19 2013
WITH A COLD CYC NW FLOW CONTINUING ARND LO PRES DEPARTING SLOWLY
THRU SE ONTARIO THIS FCST PERIOD...EXPECT SHSN TO IMPACT CMX/
IWD...WITH IFR/LIFR CONDITIONS PREDOMINATING. THE WORST CONDITIONS
TO VLIFR ARE MOST LIKELY AT THE MORE EXPOSED CMX LOCATION THRU THIS
EVNG WITH DEEPER MSTR/STRONGER WINDS. BEST OPPORTUNITY FOR MORE
IMPROVED MVFR CONDITIONS WL BE AT IWD THIS AFTN/EVNG...WHEN DRIER
AIR MOVING ESE FM MN WL LIMIT LES INTENSITY. AT SAW...DOWNSLOPING
NW WINDS SHOULD RESULT IN MAINLY MVFR CONDITIONS THRU THE FCST
PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 415 PM EDT TUE MAR 19 2013
EXPECT NW GALES/HEAVY FREEZING SPRAY TO LINGER THRU AT LEAST WED
MORNING AS DEEP LO PRES OVER SE ONTARIO EDGES SLOWLY TO THE E AND A
COLD...GUSTY NW WIND CONTINUES. WINDS/FREEZING SPRAY ARE LIKELY TO
DIMINISH OVER THE W WED AFTERNOON FARTHER FROM THE SLOWLY RETREATING
LO.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER STORM WARNING UNTIL 8 AM EDT THURSDAY FOR MIZ006-007-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY
FOR LSZ162-240>245-248>251-263>267.
GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ WEDNESDAY FOR LSZ162-
243>245-249>251-263>267.
GALE WARNING UNTIL 6 AM EDT WEDNESDAY FOR LSZ248.
GALE WARNING UNTIL 11 PM EDT THIS EVENING FOR LSZ246-247.
GALE WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
LSZ240>242.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
127 PM EDT TUE MAR 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 547 AM EDT TUE MAR 19 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW TROF EXTENDING FROM SCNTRL
CANADA INTO THE GREAT LAKES. SNOW IS DIMINISHING ACROSS UPPER MI AS
SHORTWAVE SLIPS E OF THE AREA. AT THE SFC...LOW PRES IS LOCATED OVER
CNTRL LAKE SUPERIOR. ON THE BACKSIDE OF THE LOW...STRONG NW WINDS
ARE DEVELOPING OVER FAR WRN LAKE SUPERIOR AND WILL BE REACHING UPPER
MI SHORTLY.
FCST THINKING HAS NOT CHANGED MUCH SINCE YESTERDAY. STRONG/GUSTY NW
WINDS WILL DEVELOP FROM W TO E TODAY AS SFC LOW PRES DRIFTS E. DEEP
MOISTURE/CONVERGENT CYCLONIC WNW FLOW AND INCREASINGLY COLDER AIR
WILL YIELD MDT/HVY LAKE ENHANCED SNOW DEVELOPING EARLY THIS MORNING
OVER THE W AND SPREADING TO AREAS FROM AROUND MUNISING EASTWARD LATE
MORNING/AFTN. WITH FCST SOUNDINGS SHOWING A DEEP DGZ OVER
GOGEBIC/ONTONAGON COUNTIES...SNOW SHOULD BE VERY HVY AT TIMES IN
THAT AREA TODAY. MEANWHILE...BEST LOW-LEVEL CONVERGENCE WILL SET UP
ACROSS NRN ONTONAGON COUNTY/SRN HALF OF HOUGHTON COUNTY FOR MUCH OF
TODAY/TONIGHT. BOTH FACTORS WILL RESULT IN GREATEST SNOW
ACCUMULATIONS TODAY/TONIGHT OCCURRING FROM THE HIGHER TERRAIN JUST N
OF KIWD TO THE PORCUPINE MOUNTAINS...ROCKLAND...TWIN LAKES AND
PAINESDALE. AMOUNTS UPWARDS OF 18 INCHES FROM 12Z TODAY-12Z WED SEEM
LIKELY IN THOSE AREAS...BUT WOULDN`T BE SURPRISED TO SEE MORE THAN
THAT. FARTHER N ON THE KEWEENAW...AMOUNTS WILL LIKELY TREND DOWN TO
A FOOT OR LESS UNDER WEAKER LOW-LEVEL CONVERGENCE. STRONG BOUNDARY
LAYER WINDS WILL SPREAD STEADIER SNOWS INTO BARAGA COUNTY WITH
ACCUMULATIONS LIKELY REACHING WARNING CRITERIA OVER HIGH TERRAIN. TO
THE E...AIR MASS WON`T BE QUITE AS COLD AND MAY RESULT IN DGZ BEING
DISPLACED A LITTLE ABOVE BEST UPWARD MOTION TODAY...BUT DGZ BECOMES
BETTER POSITIONED IN CONVECTIVE LAYER TONIGHT. LOW-LEVEL CONVERGENCE
IS NOT AS STRONG AS OVER THE W THROUGHOUT TODAY/TONIGHT. THESE
FACTORS SHOULD KEEP SNOW ACCUMULATIONS DOWN TO THE 6-12 INCH RANGE
BY WED MORNING WITH THE GREATEST AMOUNTS E OF MUNISING AND N/NW OF
KERY. WINDS WILL BE A SIGNIFICANT FACTOR. WITH GUSTS OF 30-40MPH...
ALONG LAKE SUPERIOR AND OVER THE KEWEENAW...BLSN WILL BE A MAJOR
ISSUE WITH WHITE-OUTS AT TIMES DUE TO HVY SNOW/BLSN. BLSN WILL BE
MOST SIGNIFICANT OVER THE KEWEENAW PENINSULA...WITH WORST CONDITIONS
THIS AFTN/EVENING.
AWAY FROM HEADLINE AREAS...-SN EARLY WILL TRANSITION TO SCT -SHSN.
DOWNSLOPE WWN WINDS WILL LIKELY BRING AN END TO -SHSN OVER THE
SCNTRL THIS AFTN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 547 AM EDT TUE MAR 19 2013
MODELS ADVERTISE PRETTY STRAIGHT FORWARD LARGE SCALE PATTERN FOR THE
LONG TERM PERIOD. AGREEMENT IN THE PRIMARY FEATURES IN THE LARGER
SCALE FLOW IS GOOD WHICH LEADS TO HIGHER CONFIDENCE FORECAST.
UPPER TROUGH FROM SOUTHERN QUEBEC/NEW ENGLAND WESTWARD ACROSS GREAT
LAKES IS MAIN FEATURE THROUGH LATE THIS WEEK. AS MOST OF UPPER JET
ENERGY ROUNDS BASE OF TROUGH...EXPECT TROUGH TO RAMBLE SLOWLY EAST
BY FRIDAY WHICH RESULTS IN HEIGHTS GRADUALLY RISING OVER UPPER GREAT
LAKES INTO NEXT WEEKEND. SFC PATTERN WELL AGREED UPON AS WELL. SFC
LOW STARTS OUT JUST EAST OF LK SUPERIOR ON WEDNESDAY THEN SHIFTS
INTO SOUTHERN QUEBEC BY THURSDAY WITH TROUGHING ENHANCED BY THE
LAKES LINGERING ACROSS LK SUPERIOR REGION. NO SIGNIFICANT CHANGE
TO PREVIOUS FCST THINKING THAT MODERATE TO AT TIMES HEAVY LK EFFECT
SNOWS IMPACT MAINLY NW SNOW BELTS OF LK SUPERIOR ON WEDNESDAY. DEEP
MOISTURE TIED TO TROUGH LINGERS AND SOUNDINGS ACTUALLY SHOW COLDEST
925-850MB TEMPS THROUGH WEDNESDAY. SFC-H95 CONVERGENCE PEGS HIGHER
TERRAIN OF WESTERN CWA ROUGHLY IRONWOOD-WAKEFIELD THROUGH TWIN LAKES
AND ATLANTIC MINE THOUGH STRONG BLYR WINDS OVER 30 KTS WILL PUSH
HEAVIER SNOW SHOWERS FARTHER INLAND THAN NORMALLY OCCURS WITH SIMILAR
WIND DIRECTION.
CONVERGENCE ALSO STRONG OVER EAST...ROUGHLY MUNISING TO NORTH OF
NEWBERRY. AGAIN STRONG WINDS MAY PUSH AT LEAST MODERATE SNOW SHOWERS
AS FAR SOUTH AS US-2 IN SCHOOLCRAFT COUNTY. HIGHEST SNOW AMOUNTS /UP
TO 6 INCHES IN 12 HRS/ EXPECTED ON WEDNESDAY. SHORTWAVE TROUGH DROPS
THROUGH THE OVERALL MEAN TROUGHING ON WEDNESDAY NIGHT. MODELS HAVE
BEEN SHOWING THIS AWHILE NOW. MAIN RESULT WILL BE WINDS SHIFTING TO
MORE NNW-N DIRECTION VERSUS NW WINDS SEEN THROUGH WEDNESDAY. SNOW
OVER NORTHWEST-WEST MARQUETTE COUNTY COULD AFFECT MORE OF THE COUNTY
WITH MORE NORTHERLY WINDS. SOUNDINGS DO INDICATE DECENT DRYING IN
WAKE OF THE WAVE IN H8-H7 LAYER BY LATER THURSDAY MORNING...BUT MOST
OF LAKE EFFECT CONVECTIVE LAYER IS WITHIN DGZ...SO SLR/S AROUND 20:1
WILL BOOST AMOUNTS. POSSIBLE THAT ADVY LEVEL SNOW AMOUNTS COULD
OCCUR LATER WEDNESDAY EVENING THROUGH MID MORNING THURSDAY OVER
MARQUETTE COUNTY...IMPACTING THU MORNING COMMUTE. LATER SHIFTS MAY
NEED TO CONSIDER HEADLINES FOR MARQUETTE COUNTY FOR THIS POTENTIAL.
DRYING SUBSIDENCE BEGINS TO TAKE BITE INTO LK EFFECT OVER WESTERN
CWA ON THURSDAY AFTN. LOCAL WRF PREFERRED WITH LOOK OF LK EFFECT
POPS/QPF THROUGH THURSDAY MORNING AND THIS INDICATES INVERSIONS
LOWERING TO LESS THAN 4KFT BY THURSDAY AFTN IN THE WEST. CURRENT
ENDING TIME OF 12Z THURSDAY FOR THE WEST LOOKING GOOD. SETUP A BIT
BETTER IN EAST THROUGH THURSDAY...BUT EVEN THERE...INVERSIONS LOWER
BLO 5KFT THOUGH THERE IS LINGERING MOISTURE BLO H7 INTO THURSDAY
EVENING. OVERALL...STRONG SUBSIDENCE/DRYING ABOVE INVERSION AND LACK
OF REAL COLD TEMPS WITHIN LK EFFECT MOIST LAYER POINTS TO
SIGNIFICANT DIMINISHING TREND TO LK EFFECT BY LATE THURSDAY
AFTN/EVENING.
EVEN SO...IT IS NOT UNTIL FRIDAY AND MAYBE EVEN AS LATE AS SATURDAY
BEFORE LOW-LEVEL FLOW OVER AREA BECOMES MORE ANTICYCLONIC AS HIGH
PRESSURE OVER NORTHERN CANADA EXPANDS INTO MANITOBA AND NORTHWEST
ONTARIO. NORTH WINDS OFF LK SUPERIOR AND TEMPS AROUND -8C KEEP
CLOUDS AND PERHAPS LGT FLURRIES GOING ON FRIDAY OVR NCNTRL UPR
MICHIGAN. AT SOME POINT...LK EFFECT WILL CEASE DUE TO INCREASING
LOW-LEVEL SHEAR AND SUBSIDENCE WITH CONTINUED WARMING TEMPS AT TOP
OF INVERSION. BY LATER IN THE WEEKEND LAST COUPLE RUNS OF GFS ARE
DEVELOPING WOUND UP SHORTWAVE/LOW PRESSURE SYSTEM IN THE CENTRAL
PLAINS. 12Z/18 MARCH ECMWF WAS MUCH MORE SUPPRESSED WITH SUCH A
SYSTEM RIDING IT ACROSS SOUTHERN TIER OF CONUS. 00Z ECMWF DID SHOW
MORE AMPLIFICATION BUT STILL KEEPS SYSTEM OVER SOUTHERN PORTION OF
OHIO VALLEY. GEM-NH/UKMET MORE WOUND UP NOW TOO...BUT LIKE ECMWF ARE
NOT NEAR AS NORTHWEST AS GFS. CAN NOT COMPLETELY COUNT OUT SOME SORT
OF SYSTEM AS TROUGHING IS PRESENT IN LARGE SCALE FROM WESTERN CANADA
INTO SOUTHERN PLAINS. PREFER THE LOOK OF WPC HAND DRAWN PROGS WITH
LOW TRACKING ACROSS SOUTHEAST CONUS AT THIS POINT. MAIN RESULT IS
QUIET WEATHER OVER UPR LAKES THROUGH THE UPCOMING WEEKEND WITH MORE
CLOUDS THAN SUNSHINE AND HIGH TEMPERATURES AT OR SLIGHTLY BLO NORMAL
IN THE LOW-MID 30S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 126 PM EDT TUE MAR 19 2013
WITH A COLD CYC NW FLOW CONTINUING ARND LO PRES DEPARTING SLOWLY
THRU SE ONTARIO THIS FCST PERIOD...EXPECT SHSN TO IMPACT CMX/
IWD...WITH IFR/LIFR CONDITIONS PREDOMINATING. THE WORST CONDITIONS
TO VLIFR ARE MOST LIKELY AT THE MORE EXPOSED CMX LOCATION THRU THIS
EVNG WITH DEEPER MSTR/STRONGER WINDS. BEST OPPORTUNITY FOR MORE
IMPROVED MVFR CONDITIONS WL BE AT IWD THIS AFTN/EVNG...WHEN DRIER
AIR MOVING ESE FM MN WL LIMIT LES INTENSITY. AT SAW...DOWNSLOPING
NW WINDS SHOULD RESULT IN MAINLY MVFR CONDITIONS THRU THE FCST
PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 547 AM EDT TUE MAR 19 2013
AS LOW PRES OVER ERN LAKE SUPERIOR DRIFTS E TODAY AND TONIGHT...NW
GALES WHICH ARE CURRENTLY DEVELOPING OVER WRN LAKE SUPERIOR WILL
EXPAND E ACROSS THE LAKE TODAY. THE GALES WILL THEN CONTINUE INTO
WED OVER THE E HALF OF THE LAKE WHILE WINDS DIMINISH SLIGHTLY BELOW
GALES OVER THE W. WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO
E WED NIGHT/THU. THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES
WILL LEAD TO PERIODS OF HVY FREEZING SPRAY THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER STORM WARNING UNTIL 8 AM EDT THURSDAY FOR MIZ006-007-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT WEDNESDAY FOR
LSZ243>245-248>251-264>267.
GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ WEDNESDAY FOR LSZ162-263-
264-266-267.
GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR LSZ243>245-249>251-265.
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY
FOR LSZ162-240>242-263.
GALE WARNING UNTIL 6 AM EDT WEDNESDAY FOR LSZ248.
GALE WARNING UNTIL 11 PM EDT THIS EVENING FOR LSZ246-247.
GALE WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
LSZ240>242.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...KC
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS BILLINGS MT
1135 AM MDT TUE MAR 19 2013
.SHORT TERM...VALID FOR TDY AND WED...
HAVE UPDATED YET AGAIN TO CARRY SCATTERED COVERAGE FOR SNOW
SHOWERS TIL 21Z. ACTIVITY IS SHALLOW WITH TOPS AROUND -20C... BUT
DENDRITIC LAYER IS MOIST AND UNSTABLE AT LOW LEVELS...THUS THE
SNOW SHOWERS CONTINUE WITHIN BLYR CONVERGENT REGION. SUBSIDENCE
SEEN WORKING INTO CENTRAL MT NOW...SO DIMINISHING TREND WILL BEGIN
OVER THE NEXT 1-2 HOURS. JKL
PREVIOUS DISCUSSION...
WEAK SHORTWAVE EMBEDDED IN AN UNSTABLE NW FLOW COMBINED WITH LOW
LEVEL FRONTOGENESIS ALONG SFC BOUNDARY AND TEMPERATURES FAVORABLE
FOR DENDRITIC GROWTH ARE ALLOWING FOR LIGHT SNOW SHOWERS/FLURRIES
TO CONTINUE IN AN AREA FROM JUDITH GAP...ROUNDUP AND BILLINGS
EAST/SOUTHWARD TO FORSYTH AND SHERIDAN. OBS/WEB CAMS SHOW JUST A
DUSTING TO LESS THAN A HALF INCH FOR MOST OF THIS AREA. CLOUD TOPS
NOT WARMING YET BUT THEY WILL SHORTLY AS SHORTWAVE ENERGY DEPARTS
AND FRONTOGENESIS WEAKENS...PER RAP WHICH SEEMS TO HAVE A FAIR
HANDLING OF THE CURRENT SITUATION. HAVE EXPANDED SCATTERED
COVERAGE FOR THIS ACTIVITY... WHICH WILL PROBABLY PERSIST TO A
COUPLE HOURS BEYOND 18Z INTO THE AFTERNOON...BUT OTHERWISE A
DIMINISHING TREND IS ANTICIPATED THIS AFTERNOON AS HEIGHTS BEGIN
TO RISE FROM THE WEST. DOWNSLOPE WINDS AND SUN WILL ALLOW FOR
TEMPS INTO THE 40S OUT WEST...BUT LOW LEVEL NORTH TO EAST WINDS
AND POOR MIXING WILL KEEP TEMPS IN THE 30S CENTRAL AND EAST
PARTS...AND EVEN MID TO UPPER 20S ALONG THE DAKOTAS BORDER WHERE
COLD AIR ASSOCIATED WITH CANADIAN SFC RIDGE WILL BE DEEPEST.
AS FOR BILLINGS...LIGHT SNOW SHOWERS/FLURRIES WILL TAPER OFF BY
NOON BUT LIGHT TO EAST WINDS WILL KEEP TEMPS ON THE COOLISH SIDE
TODAY WITH HIGHS IN THE UPPER 30S TO NEAR 40...IE ABOUT 10
DEGREES BELOW NORMAL.
LOOK FOR A DRY NIGHT TONIGHT AS UPPER RIDGE BUILDS OVER THE
REGION. THIS WILL LEAD TO A WARMER WEDNESDAY PRIOR TO WED NITE/THU
SHORTWAVE/COLD FRONT.
JKL
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM AND LONG RANGE MODELS REMAIN IN GOOD AGREEMENT. ALL MODELS
CONTINUE TO ADVERTISE UNSETTLED WEATHER TREND FOR THURSDAY THROUGH
EARLY NEXT WEEK ALONG WITH BELOW NORMAL TEMPERATURES.
MAIN WEATHER PRODUCER WILL BE ON THURSDAY AS AN UPPER LEVEL TROUGH
OF LOW PRESSURE MOVES IN FROM THE PACIFIC NORTHWEST. LEFT EXIT
REGION OF THE JET ASSOCIATED WITH THIS TROUGH WILL BE MOVING OVER
OUR AREA ALONG WITH MODERATE QG FORCING. GOOD PACIFIC MOISTURE
FEED INDICATED BY MODELS AND THIS WILL COMBINE WITH AN INVERTED
SURFACE TROUGH TO BRING SNOW TO OUR SOUTHWEST MOUNTAINS AND AREAS
WEST OF BILLINGS THURSDAY MORNING. THIS FORCING WITH THE UPPER
TROUGH WILL SHIFT EASTWARD THROUGH THE DAY. HAVE RAISED POPS IN
THE WEST FOR THURSDAY MORNING AND ALSO ALONG THE FOOTHILLS FROM
RED LODGE TO MC LEOD AS A SHORT PERIOD OF UPSLOPE FLOW WILL TAKE
PLACE WITH THE PASSAGE OF A COLD FRONT MOVING IN FROM THE NORTH.
ALSO INCREASED POPS TO LIKELY IN OUR EASTERN ZONES WITH INVERTED
SURFACE TROUGH MOVING OVER THIS AREA.
FRIDAY INTO EARLY NEXT WEEK WILL REMAIN UNSETTLED AS A BROAD
UPPER LEVEL TROUGH WILL REAMIN OVER THE NORTHERN PLAINS. MAIN LIFT
WITH THE TROUGH WILL STAY NORTH OF OUR AREA BUT ENOUGH ENERGY FROM
WEAK IMPULSES MOVING THROUGH TO BRING SCATTERED RAIN OR SNOW
SHOWERS. TEMPERATURES WILL BE BLOW SEASONAL NORMALS AS COLDER
CANADIAN AIR WILL FILTER INTO OUR AREA. HIGH TEMPERATURES WILL BE
IN THE UPPER 30S TO LOWER 40S. DID LOWER OVERNIGHT TEMPERATURES
WITH MODELS ADVECTING COLDER AIR INTO SOUTHERN MONTANA DURING
THIS TIME PERIOD. RICHMOND
&&
.AVIATION...
ISOLATED TO SCATTERED SNOW SHOWERS CONTINUE TO IMPACT WESTERN
ROUTES...INCLUDING KBIL AND KSHR...AS WELL AS HIGH TERRAIN.
LOCALIZED REDUCED FLIGHT CONDITIONS...AS LOW AS IFR AND LIFR CIGS
AND VIS AT TIMES. MOUNTAIN OBSCURATIONS CAN BE EXPECTED THIS
MORNING WITH THE SNOW SHOWERS. PRECIPITATION SHOULD BEGIN TO CLEAR
FROM WEST TO EAST BY LATE MORNING...WITH MAINLY VFR CONDITIONS
PREVAILING THROUGH THE REMAINDER OF THE DAY. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 038 026/056 032/042 027/038 022/041 023/040 025/039
3/J 01/E 45/W 32/W 21/B 12/J 22/W
LVM 042 026/054 034/042 024/038 019/036 019/038 020/038
0/B 02/W 56/W 32/J 22/J 22/J 22/J
HDN 037 023/056 029/043 026/039 023/040 022/041 025/040
3/J 01/B 46/W 42/W 21/B 12/W 21/B
MLS 031 021/046 026/038 024/037 022/039 020/040 022/041
1/B 01/B 26/W 42/J 11/B 11/B 11/B
4BQ 033 020/047 024/039 023/036 021/037 020/039 020/040
2/J 00/B 16/W 42/J 11/B 12/W 21/B
BHK 025 014/037 019/031 019/033 017/033 016/034 017/035
1/B 00/N 16/J 43/J 11/B 11/B 11/E
SHR 034 018/052 027/039 021/034 018/036 017/036 018/034
4/J 01/B 26/W 43/J 22/J 23/J 21/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
1018 AM MDT TUE MAR 19 2013
.SHORT TERM...VALID FOR TDY AND WED...
HAVE UPDATED AGAIN TO EXTEND ISOLATED POPS FOR LIGHT SNOW SHOWERS
TIL 21Z IN OUR SOUTH CENTRAL PARTS. LOCALIZED HALF INCH ACCUMS
EXPECTED IN HEAVIER SNOW BANDS. OTHERWISE NO CHANGES. JKL
PREVIOUS DISCUSSION ISSUED 905 AM...
WEAK SHORTWAVE EMBEDDED IN AN UNSTABLE NW FLOW COMBINED WITH LOW
LEVEL FRONTOGENESIS ALONG SFC BOUNDARY AND TEMPERATURES FAVORABLE
FOR DENDRITIC GROWTH ARE ALLOWING FOR LIGHT SNOW SHOWERS/FLURRIES
TO CONTINUE IN AN AREA FROM JUDITH GAP...ROUNDUP AND BILLINGS
EAST/SOUTHWARD TO FORSYTH AND SHERIDAN. OBS/WEB CAMS SHOW JUST A
DUSTING TO LESS THAN A HALF INCH FOR MOST OF THIS AREA. CLOUD TOPS
NOT WARMING YET BUT THEY WILL SHORTLY AS SHORTWAVE ENERGY DEPARTS
AND FRONTOGENESIS WEAKENS...PER RAP WHICH SEEMS TO HAVE A FAIR
HANDLING OF THE CURRENT SITUATION. HAVE EXPANDED SCATTERED
COVERAGE FOR THIS ACTIVITY... WHICH WILL PROBABLY PERSIST TO A
COUPLE HOURS BEYOND 18Z INTO THE AFTERNOON...BUT OTHERWISE A
DIMINISHING TREND IS ANTICIPATED THIS AFTERNOON AS HEIGHTS BEGIN
TO RISE FROM THE WEST. DOWNSLOPE WINDS AND SUN WILL ALLOW FOR
TEMPS INTO THE 40S OUT WEST...BUT LOW LEVEL NORTH TO EAST WINDS
AND POOR MIXING WILL KEEP TEMPS IN THE 30S CENTRAL AND EAST
PARTS...AND EVEN MID TO UPPER 20S ALONG THE DAKOTAS BORDER WHERE
COLD AIR ASSOCIATED WITH CANADIAN SFC RIDGE WILL BE DEEPEST.
AS FOR BILLINGS...LIGHT SNOW SHOWERS/FLURRIES WILL TAPER OFF BY
NOON BUT LIGHT TO EAST WINDS WILL KEEP TEMPS ON THE COOLISH SIDE
TODAY WITH HIGHS IN THE UPPER 30S TO NEAR 40...IE ABOUT 10
DEGREES BELOW NORMAL.
LOOK FOR A DRY NIGHT TONIGHT AS UPPER RIDGE BUILDS OVER THE
REGION. THIS WILL LEAD TO A WARMER WEDNESDAY PRIOR TO WED NITE/THU
SHORTWAVE/COLD FRONT.
JKL
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM AND LONG RANGE MODELS REMAIN IN GOOD AGREEMENT. ALL MODELS
CONTINUE TO ADVERTISE UNSETTLED WEATHER TREND FOR THURSDAY THROUGH
EARLY NEXT WEEK ALONG WITH BELOW NORMAL TEMPERATURES.
MAIN WEATHER PRODUCER WILL BE ON THURSDAY AS AN UPPER LEVEL TROUGH
OF LOW PRESSURE MOVES IN FROM THE PACIFIC NORTHWEST. LEFT EXIT
REGION OF THE JET ASSOCIATED WITH THIS TROUGH WILL BE MOVING OVER
OUR AREA ALONG WITH MODERATE QG FORCING. GOOD PACIFIC MOISTURE
FEED INDICATED BY MODELS AND THIS WILL COMBINE WITH AN INVERTED
SURFACE TROUGH TO BRING SNOW TO OUR SOUTHWEST MOUNTAINS AND AREAS
WEST OF BILLINGS THURSDAY MORNING. THIS FORCING WITH THE UPPER
TROUGH WILL SHIFT EASTWARD THROUGH THE DAY. HAVE RAISED POPS IN
THE WEST FOR THURSDAY MORNING AND ALSO ALONG THE FOOTHILLS FROM
RED LODGE TO MC LEOD AS A SHORT PERIOD OF UPSLOPE FLOW WILL TAKE
PLACE WITH THE PASSAGE OF A COLD FRONT MOVING IN FROM THE NORTH.
ALSO INCREASED POPS TO LIKELY IN OUR EASTERN ZONES WITH INVERTED
SURFACE TROUGH MOVING OVER THIS AREA.
FRIDAY INTO EARLY NEXT WEEK WILL REMAIN UNSETTLED AS A BROAD
UPPER LEVEL TROUGH WILL REAMIN OVER THE NORTHERN PLAINS. MAIN LIFT
WITH THE TROUGH WILL STAY NORTH OF OUR AREA BUT ENOUGH ENERGY FROM
WEAK IMPULSES MOVING THROUGH TO BRING SCATTERED RAIN OR SNOW
SHOWERS. TEMPERATURES WILL BE BLOW SEASONAL NORMALS AS COLDER
CANADIAN AIR WILL FILTER INTO OUR AREA. HIGH TEMPERATURES WILL BE
IN THE UPPER 30S TO LOWER 40S. DID LOWER OVERNIGHT TEMPERATURES
WITH MODELS ADVECTING COLDER AIR INTO SOUTHERN MONTANA DURING
THIS TIME PERIOD. RICHMOND
&&
.AVIATION...
ISOLATED TO SCATTERED SNOW SHOWERS CONTINUE TO IMPACT WESTERN
ROUTES...INCLUDING KBIL AND KSHR...AS WELL AS HIGH TERRAIN.
LOCALIZED REDUCED FLIGHT CONDITIONS...AS LOW AS IFR AND LIFR CIGS
AND VIS AT TIMES. MOUNTAIN OBSCURATIONS CAN BE EXPECTED THIS
MORNING WITH THE SNOW SHOWERS. PRECIPITATION SHOULD BEGIN TO CLEAR
FROM WEST TO EAST BY LATE MORNING...WITH MAINLY VFR CONDITIONS
PREVAILING THROUGH THE REMAINDER OF THE DAY. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 038 026/056 032/042 027/038 022/041 023/040 025/039
2/J 01/E 45/W 32/W 21/B 12/J 22/W
LVM 042 026/054 034/042 024/038 019/036 019/038 020/038
0/B 02/W 56/W 32/J 22/J 22/J 22/J
HDN 037 023/056 029/043 026/039 023/040 022/041 025/040
3/J 01/B 46/W 42/W 21/B 12/W 21/B
MLS 031 021/046 026/038 024/037 022/039 020/040 022/041
1/B 01/B 26/W 42/J 11/B 11/B 11/B
4BQ 033 020/047 024/039 023/036 021/037 020/039 020/040
2/J 00/B 16/W 42/J 11/B 12/W 21/B
BHK 025 014/037 019/031 019/033 017/033 016/034 017/035
1/B 00/N 16/J 43/J 11/B 11/B 11/E
SHR 034 018/052 027/039 021/034 018/036 017/036 018/034
4/J 01/B 26/W 43/J 22/J 23/J 21/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
359 PM CDT TUE MAR 19 2013
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
MORNING UPPER AIR ANALYSIS INDICATES LONGWAVE TROUGHING OVER THE
EASTERN-HALF OF THE CONUS WITH RIDGING OVER THE WEST.
NORTHWESTERLY MID AND UPPER LEVEL FLOW PERSISTS OVER THE CENTRAL
PLAINS AS A RESULT. TROPOSPHERIC FLOW OVER OUR AREA MAXES OUT AT
AROUND 120KTS PER 12Z SOUNDING DATA FROM KOAX AND KLBF. WATER
VAPOR IMAGERY ALSO INDICATES A SUBTLE MID LEVEL PERTURBATION OVER
EASTERN MONTANA...MOVING TO THE SOUTHEAST. AT THE SURFACE A TROUGH
IS NOTED EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA
AND KANSAS...WITH A COLD FRONT ALSO NOTED OVER THE DAKOTAS. THE
LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTHWEST AS
A RESULT.
PROXIMITY SOUNDINGS FROM ACROSS CWA...PER RAP ANALYSIS AND LAPS
DATA...SUGGEST VERY STEEP LOW TO MID LEVEL LAPSE RATES ARE IN
PLACE...WITH NEARLY DRY ADIABATIC LAPSE RATES NOTED FROM THE
SURFACE TO BETWEEN 750MB AND 700MB ACROSS MUCH OF OUR AREA. AS A
RESULT...MODEST SBCAPE VALUES ON THE ORDER OF 100-200J/KG ARE IN
PLACE ACROSS MUCH OF THE CWA. AN EXPANDING CU FIELD AS BEEN NOTED
ON SATELLITE IMAGERY ACROSS MUCH OF NEBRASKA AS A RESULT...WITH
KUEX AND KLNX SUGGESTING ELEVATED PRECIPITATION HAS RESULTED. SOME
OF THIS PRECIPITATION IS MAKING IT TO THE SURFACE IN THE FORM OF
RAIN AND GRAUPEL...BOTH OF WHICH WAS OBSERVED AT THE OFFICE
BETWEEN 19Z AND 20Z. IN ADDITION...A COUPLE OF CG STRIKES HAVE
BEEN DETECTED FROM HALL COUNTY INTO BUFFALO COUNTY WITH SOME OF
THE MORE INTENSE CELLS. WITH ANY OMEGA STILL REMAINING WELL
NORTHWEST OF OUR AREA OVER THE NORTHERN HIGH PLAINS...IN THE
VICINITY OF THE AFOREMENTIONED MID LEVEL PERTURBATION...IT APPEARS
THE CURRENT ACTIVITY IS BEING PROMOTED BY DIABATIC HEATING ALONE.
SO...THIS ACTIVITY SHOULD CONTINUE THROUGH 22Z OR 23Z BEFORE THE
LOSS OF DIABATIC HEATING IS REALIZED LATER THIS EVENING. WENT
AHEAD WITH ISOLATED RAIN AND SNOW SHOWERS...ALONG WITH OCCASIONAL
LIGHTNING...IN THE FORECAST THROUGH 00Z.
THE SAME PROXIMITY SOUNDINGS FROM ACROSS THE CWA ALSO INDICATE
VERY DRY LOWER TROPOSPHERIC AIR IN PLACE ACROSS THE AREA...THUS
RESULTING IN DEEP INVERTED-V SOUNDINGS ACROSS THE ENTIRE CWA.
GIVEN THE ABUNDANT VIRGA NOTED HERE AT THE OFFICE...ALONG WITH THE
UPDRAFT STRENGTH NOTED FROM KUEX THROUGH THE PAST HOUR...FELT IT
PRUDENT TO INTRODUCE BRIEF WIND GUSTS TO AROUND 50 MPH IN THE HWO
THROUGH THIS EVENING.
THE MID LEVEL PERTURBATION...CURRENTLY OVER THE NORTHERN HIGH
PLAINS...IS EXPECTED TO SWEEP OVER OUR AREA TONIGHT. ANY OMEGA IN
ASSOCIATION WITH THIS FEATURE IS EXPECTED TO REMAIN WEAK AND WITH
NO OTHER SIGNIFICANT SOURCE OF LIFT DURING THE SHORT TERM
FORECAST PERIOD...DRY CONDITIONS ARE FORECAST TONIGHT INTO
TOMORROW.
THE PASSAGE OF THE MID LEVEL PERTURBATION WILL ALSO HELP PUSH THE
LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER THE DAKOTAS...ACROSS
OUR AREA TONIGHT. THIS WILL IN TURN ALLOW A COOLER AIRMASS INTO
OUR REGION THUS RESULTING IN SOMEWHAT COOLER WEDNESDAY MORNING
LOWS WHEN COMPARED TO TUESDAY MORNING. OVERNIGHT LOWS IN THE TEENS
AND 20S ARE CURRENTLY FORECAST FOR TONIGHT AS A RESULT. THE
SURFACE RIDGE IS THEN EXPECTED TO PUSH OFF TO OUR EAST DURING THE
DAY WEDNESDAY...WITH LOW LEVEL RETURN FLOW AND RESULTANT WARM AIR
ADVECTION ALLOWING WEDNESDAY AFTERNOON HIGHS TO CLIMB INTO THE 40S
AND LOWER 50S FOR MOST LOCATIONS ACROSS THE AREA.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
WEDNESDAY NIGHT THROUGH TUESDAY. PRIMARY FORECAST CONCERN REVOLVES
AROUND A MESSY PATTERN WITH MULTIPLE PRECIPITATION CHANCES
DURING THE LATE WORK WEEK/WEEKEND TIME FRAME.
STILL EXPECTING THE START OF THE LONG TERM PERIOD TO BE DRY...WITH
MODELS IN GOOD AGREEMENT SHOWING NORTHWESTERLY FLOW SET UP IN THE
UPPER LEVELS ACROSS THE REGION WEDNESDAY EVENING INTO THE
OVERNIGHT HOURS...WITH AN ELONGATED LOW PRESSURE SYSTEM SPREAD
FROM THE NORTHEASTERN CONUS THROUGH THE GREAT LAKES...AND
SHORTWAVE RIDGING OVER THE ROCKIES AHEAD OF ANOTHER TROUGH ALONG
THE WEST COAST. AT THE SURFACE...THE CWA SITS BETWEEN A RIDGE OF
HIGH PRESSURE ALONG/JUST EAST OF THE MISSOURI RIVER...AND LOW
PRESSURE EXTENDING FROM THE NORTHERN ROCKIES DOWN INTO SERN
COLORADO...BRINGING SOUTHEASTERLY WINDS TO THE AREA.
AS WE GET INTO EARLY THURSDAY MORNING...STILL SEEING THE MAIN
MID/UPPER LEVEL TROUGH/LOW PRESSURE SYSTEM IN PLACE TO THE
WEST...WITH THE FIRST OF A COUPLE OF DISTURBANCES EJECTED OUT
AHEAD OF IT BEGINNING TO AFFECT THE REGION. MAIN CHANGE WITH THE
MODELS HAS BEEN WITH MORE AGREEMENT BACKING OFF THE COVERAGE OF
PRECIPITATION ACROSS THE CWA...THERE IS PLENTY OF DRIER AIR TO
OVERCOME...AND BETTER CHANCES LOOK TO BE ACROSS EASTERN PORTIONS
OF THE CWA DURING THE DAY ON THURSDAY AS THE MID LEVEL TROUGH AXIS
SWINGS THROUGH AND FRONTOGENETICAL LIFT INCREASES. REALLY TAPERED
BACK POPS...ESP ACROSS THE WRN THIRD OF THE CWA...IT IS POSSIBLE
AFTER 12Z THURSDAY SOME WESTERN LOCATIONS MAY NOT SEE MUCH OF
ANYTHING. DIDNT WANT TO COMPLETELY PULL POPS YET...WANT TO SEE
SOME CONSISTENCY WITH THIS TREND FIRST. DECIDED TO HOLD ON TO THE
MIXED PRECIPITATION ACROSS THE SWRN CWA DURING THE EARLY/MID
MORNING HOURS ON THURSDAY...BUT CONFIDENCE IS NOT HIGH IN IT
OCCURRING. IF PRECIPITATION OCCURS AT ALL IN THAT PART OF THE
CWA...CANT COMPLETELY RULE OUT A BRIEF PERIOD OF MORE OF A
MIX...BUT NOT EXPECTING IT TO AMOUNT TO MUCH.
BUMPED UP HIGH TEMPERATURES ON THURSDAY ONCE AGAIN WITH MODELS
TRENDING TOWARD THE POTENTIAL FOR DRIER CONDITIONS DURING THE
AFTERNOON HOURS...SWRN LOCATIONS COULD REACH INTO THE LOWER/MID
40S. THINK THE NORTHEAST HALF WILL STRUGGLE WITH PRECIP/MORE CLOUD
COVER LINGERING LONGER INTO THE DAY.
SHOULD SEE A LULL IN THE ACTIVITY LATER IN THE DAY THURSDAY AND
INTO THURSDAY EVENING...BUT IT WILL BE A BRIEF BREAK WITH THE
NEXT DISTURBANCE TAKING AIM ON THE REGION. MODELS SHOWING THE MAIN
TROUGH OVER THE NORTHWESTERN CONUS/NRN ROCKIES TRYING TO EVOLVE
INTO A CLOSED CIRCULATION AS ANOTHER 110+KT UPPER LEVEL JET STREAK
DIGS INTO THE WEST COAST. ANOTHER SHORTWAVE DISTURBANCE EJECTED
OUT FROM THIS SYSTEM LOOKS TO BRING ANOTHER CHANCE FOR
PRECIPITATION TO THE CWA. THERE CONTINUE TO BE SOME SLIGHT
DIFFERENCES...BUT MODELS HAVE TRENDED TOWARD MORE AGREEMENT
SHOWING THE TIMING COMING DURING THURSDAY NIGHT INTO THE FIRST
HALF OF THE DAY ON FRIDAY. THINKING THE PRIMARY PRECIPITATION TYPE
FOR MOST WILL BE SNOW...BUT CANT RULE OUT MORE OF A RA/SN
MIX...MAINLY ACROSS THE SOUTHERN CWA. LIKE THURSDAY...TRENDED BACK
POPS ON FRIDAY...THE BETTER CHANCES COME DURING THE 00-12Z FRIDAY
TIME FRAME...WITH VERY LITTLE IN THE WAY OF POPS DURING THE
AFTERNOON HOURS. BECAUSE OF THIS...ALSO BUMPED UP HIGHS ON
FRIDAY...WITH MID 30S IN THE NORTHEAST TO LOWER/MID 40S IN THE
SOUTHWEST.
FRIDAY AFTERNOON AND INTO THE OVERNIGHT HOURS WILL BRING ANOTHER
LULL IN THE ACTIVITY...BEFORE FOCUS QUICKLY TURNS TO A STRONGER
SYSTEM WHICH WILL BRING THE POTENTIAL FOR MORE WIDESPREAD
ACCUMULATING SNOWFALL TO THE REGION. BY EARLY SATURDAY
MORNING...MODELS HAVE STARTED TO COME INTO BETTER AGREEMENT
SHOWING THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE BORDER
OF MONTANA/CANADA...WHILE A PIECE OF ENERGY SWINGING FURTHER SOUTH
INTO THE ROCKIES DOES THE SAME...AND ITS THIS SOUTHERN ONE WHICH
WILL AFFECT OUR CWA. LIFT WILL BEGIN TO INCREASE ACROSS THE CWA
OUT AHEAD OF THIS SYSTEM LATE FRIDAY NIGHT...ALREADY BRINGING
PRECIPITATION CHANCES TO MAINLY THE WESTERN HALF OF THE CWA.
THROUGH THE DAYTIME HOURS ON SATURDAY THIS UPPER LEVEL LOW WILL
CONTINUE TO PUSH EAST...BRINGING INCREASING PRECIPITATION
CHANCES...AND BY 00Z LOOKS TO BE OVER CENTRAL/ERN PORTIONS OF
COLORADO. THERE ARE SOME TIMING DIFFERENCES...THE ECMWF/GFS ARE IN
PRETTY GOOD AGREEMENT...WITH THE GEM A TOUCH SLOWER. WHAT HAPPENS
THEN THROUGH THE OVERNIGHT HOURS SATURDAY NIGHT AND THEN INTO
SUNDAY IS GOING TO DEPEND ULTIMATELY ON THE PATH/TIMING OF THIS
UPPER LEVEL LOW. THE TIMING/PATH DIFFERENCES BETWEEN THE MODELS
CONTINUE...BUT THEY ALL BRING MORE WIDESPREAD SNOWFALL
ACCUMULATION. THIS IS ESPECIALLY TRUE WITH THE GEM...WHICH IS THE
SLOWEST AND MOST WOUND UP SYSTEM COMPARED TO THE ECMWF/GFS...BUT
ITS PATH IS SOMEWHAT IN BETWEEN THE TWO...TAKING IT MORE THROUGH
CENTRAL KS. THERE ARE PLENTY OF THINGS TO WORK OUT IN THE COMING
DAYS...AND EXPECT MODEL CHANGES...BUT THOSE WITH WEEKEND PLANS
NEED TO KEEP AN EYE ON THIS SYSTEM. AS FAR AS TEMPERATURES
GO...EXPECTING HIGHS TO STRUGGLE TO GET OUT OF THE MID 30S BOTH
SATURDAY AND SUNDAY.
LOOKING AHEAD TO MONDAY AND TUESDAY...KEPT THE FORECAST DRY...BUT
THE MESSY UPPER LEVEL PATTERN REMAINS. MODELS KEEP THE REGION
UNDER THE INFLUENCE OF A BROAD TROUGH...WITH PIECES OF
ENERGY/LOW PRESSURE SYSTEMS ROTATING AROUND EACH OTHER. IN THIS
PATTERN...CERTAINLY WOULNDT BE SEEING MUCH/IF ANY WARM UP...WITH
HIGHS REMAINING IN THE 30S /AVERAGE FOR THIS TIME OF YEAR IS THE
LOWER 50S/...AND ITS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME
OF THIS ENERGY COULD BRING ANOTHER CHANCE FOR PRECIPITATION...ESP
TUESDAY. BUT AT THIS POINT...WITH THERE ALREADY ENOUGH UNCERTAINTY
THROUGH THE WEEKEND...WASNT CONFIDENT ENOUGH TO GO WITH ANY POPS
FOR DAY 7.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1216 PM CDT TUE MAR 19 2013
VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS.
AFTERNOON CU FIELD WITH BASES NEAR 7000FT AGL ARE EXPECTED
TODAY...WITH SCATTERED CLOUDS NEAR 8000FT AGL ALSO EXPECTED
THROUGH THE OVERNIGHT HOURS. THE SURFACE WIND WILL REMAIN FROM THE
NORTH/NORTHWEST...SUSTAINED AT AROUND 17KTS AND GUSTING AROUND
25KTS. THE WIND WILL DIMINISH IN INTENSITY TONIGHT...SUSTAINED
AROUND 10KTS...BUT WILL REMAIN FROM THE NORTH. VISIBILITY
RESTRICTION IS NOT EXPECTED AT KGRI THROUGH THE NEXT 24 HOURS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...BRYANT
LONG TERM...ADO
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
224 PM CDT TUE MAR 19 2013
.SHORT TERM...
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A VERTICALLY
STACKED LOW PRESSURE SYSTEM STALLED OVER FAR EASTERN LAKE SUPERIOR
THIS AFTERNOON. CLEARING SKIES ARE GRADUALLY OCCURRING FROM SW TO
NE ACROSS THE STATE AND HAS NOW REACHED FROM ABOUT RHINELANDER TO
MANITOWOC. STILL GETTING AN OCCASIONAL LIGHT SNOW OR FLURRY REPORT
OVER N-C WISCONSIN...AND VSBYS ARE ALSO OCCASIONALLY FALLING TO
AROUND 4SM DUE TO BLOWING SNOW. WIND GUSTS HAVE BEHAVED THEMSELVES
SO FAR THIS AFTERNOON...AS PEAK GUSTS WITHIN THE FORECAST AREA HAVE
REMAINED BELOW 35 KTS. SHEBOYGAN SEEMS TO BE THE LONE SPOT WHERE
GUSTS HAVE REACHED GREATER THAN 40 MPH. AS THE UPPER LOW REMAINS
STATIONARY TONIGHT AND DROPS SOUTH TOMORROW...SNOW CHANCES AND CLOUD
COVER ARE THE MAIN FORECAST CONCERNS.
TONIGHT...UPPER LEVEL LOW PRESSURE TO SIT AND SPIN OVER EASTERN LAKE
SUPERIOR TONIGHT. INCOMING LOW LEVEL DRYING FROM THE SW HAS
POTENTIAL TO REACH THE U.P. BORDER WHERE WNW WINDS SHOULD KEEP
CLOUDS ALONG AND NORTH OF THE BORDER THROUGH THE EVENING. AS A
RESULT...WENT MUCH MORE OPTIMISTIC WITH CLOUD COVER THIS EVENING
WITH MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS ACROSS THE MAJORITY OF
THE FORECAST AREA EXPECT FOR NEAR THE BORDER. AFTER MIDNIGHT...MID
AND UPPER MOISTURE PIVOT AROUND THE UPPER LOW AND BACK SOUTH ACROSS
NORTHERN WISCONSIN. THINK CLOUDS WILL INCREASE ONCE AGAIN WITH SNOW
SHOWERS RETURNING TO NORTH-CENTRAL WISCONSIN. NOT EXPECTING MUCH
MORE THAN A HALF INCH ACCUM THOUGH. COLD ADVECTION WILL OCCUR
THROUGH THE NIGHT AND LOWS UPSTREAM WERE IN THE SINGLE DIGITS ABOVE
ZERO OVER EASTERN MINNESOTA. THAT SOUNDS ABOUT RIGHT FOR LOWS
TONIGHT...SINCE BL WINDS LOOK TO BE TOO STRONG FOR DECOUPLING. SO
RAISED LOWS A DEGREE OR TWO.
WEDNESDAY...MOISTURE WILL CONTINUE TO SURGE SOUTH ACROSS CENTRAL AND
SOUTHERN WISCONSIN WEDNESDAY MORNING. WITH STEEPENING LOW LEVEL
LAPSE RATES...SKIES SHOULD CLOUD UP PRETTY QUICKLY BY MID TO LATE
MORNING. LIGHT SNOW SHOWERS AND FLURRIES SHOULD BE SPREADING FROM
NORTH TO SOUTH FROM LATE MORNING THROUGH THE AFTERNOON HOURS...WHEN
THE SHORTWAVE THAT CREATED THE SNOW YESTERDAY...ROTATES AROUND THE
BACKSIDE OF THE UPPER LOW AND DROPS SOUTH ACROSS THE STATE. LOW
LEVEL WINDS DO VEER TO THE NW TOMORROW AFTERNOON WHICH WILL BE
BETTER FOR LAKE ENHANCEMENT. SO WILL GIVE POPS A BOOST TOMORROW
EVERYWHERE. POTENTIAL WILL BE THERE FOR A HALF TO AN INCH OF NEW
SNOW ACROSS THE AREA.
.LONG TERM...
SOME HINTS THAT CURRENT COLD PATTERN MAY WANE TOWARDS END OF MODEL
RUN AS BLOCKY PATTERN BREAKS DOWN...THOUGH BEFORE THAT DRY WITH
BELOW NORMAL TEMPERATURES CONTINUE.
WED NIGHT THROUGH THU...INFLUENCE OF UPPER LOW OVER THE EASTERN
LAKES TO LESSEN WITH RIDGE MOVING IN. THOUGH WITH CYCLONIC FLOW
HAVE STAYED WITH HIGHER CLOUD COVER ON WED NIGHT...PARTLY CLOUDY
BY THU. WINDS EXPECTED TO BE LIGHTER BUT NOT DECOUPLE
TOTALLY...ESPECIALLY EAST. WITH THESE THOUGHTS...RAISED TEMPS A
BIT WITH COLDEST SPOT EXPECTED OVER CENTRAL WHERE WINDS WILL BE LIGHTEST.
WITH WINDS SHIFTING NORTH AFTER PASSAGE OF SHORT WAVE EXPECT LAKE
EFFECT SHOWERS TO CONTINUE...THOUGH AS RIDGE BUILDS IN INVERSION
HEIGHTS LOWER AND DRIER AIR WORKS IN. HAVE TRENDED DOWN ON
POPS...ESPECIALLY AFTER MIDNIGHT WED NIGHT.
THU NIGHT ONWARD...AIR MASS TRENDING TO MODERATE WITH
TIME...THOUGH NO APPEARANCE OF ANY SIG WAA. WILL SLOWLY BRING
TEMPS UP...THOUGH STILL HAVE HIGHS SOME 5 TO 10 DEGREES BELOW
NORMS. PACIFIC SYSTEM TO DROP SE INTO SOUTHERN PLAINS...THEN LIFT
OUT INTO THE OHIO VALLEY MONDAY TIMEFRAME. SOME DIFFERENCES IN
THE MODELS WITH GFS STRONGER AND FURTHER NORTH BRINGING QPF NORTH
INTO THE REGION. HAVE DOWN PLAYED THAT SCENARIO IN GRIDS...AS GFS
LACK CONSISTENCY IN LATTER PERIODS. HAVE TRENDED TOWARDS ECENS.
CANADIAN HIGH PRESSURE TO DOMINATE AT THE SURFACE WITH WINDS
SHIFTING NE SAT INTO TUE. HAVE BROUGHT CLOUDS UP SLIGHTLY IN THE
EAST WITH FLOW OFF LAKE...THOUGH WITH LIMITED INSTABILITY WILL
STAY DRY.
&&
.AVIATION...MAINLY MVFR CIGS AND VSBYS WITH SCATTERED SNOW
SHOWERS TO PERSIST THIS MORNING. SNOW SHOWERS AND BLOWING SNOW
WITH STRONG WEST WINDS WILL PRODUCE IFR VSBYS AT TIMES THIS
MORNING WITH THE FRESH SNOW. AS THE SYSTEM SHIFTS EAST LATER
TODAY...CONDITIONS TO IMPROVE TO MVFR CIGS AND VFR VSBYS
WITH SOME DECREASE IN THE SUSTAINED WEST WIND SPEED BY EARLY THIS
EVENING. SURFACE WIND GUSTS TO 25 MPH MAY LINGER OVER NORTHEAST
WISCONSIN THROUGH WEDNESDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/TE