Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/15/13
AREA FORECAST DISCUSSION
NWS EUREKA CA
358 AM PST WED FEB 13 2013
.SYNOPSIS...
A STRONG AND PERSISTENT RIDGE OF HIGH PRESSURE WILL KEEP NORTHWEST
CALIFORNIA DRY THROUGH AT LEAST SATURDAY MORNING. WHILE MORNING
CLOUDS ALONG THE NORTH COAST WILL GIVE WAY TO SUNSHINE THERE WILL
STILL BE A COOL BREEZE THIS AFTERNOON. INTERIOR AREAS WILL STAY
SUNNY OUTSIDE OF AREAS OF VALLEY FOG. OFFSHORE FLOW WILL BRING
WARMER CONDITIONS TO THE COAST LATER THURSDAY AND FRIDAY.
&&
.SHORT TERM...
STRATUS IS MUCH MORE WELL-ESTABLISHED ALONG THE COAST BETWEEN CAPE
MENDOCINO AND TRINIDAD EARLY THIS MORNING. WITH UPPER RIDGING
BUILDING OVER THE EASTERN PACIFIC SFC HIGH PRESSURE HAS
STRENGTHENED...RESULTING IN AN INCREASED ONSHORE GRADIENT ALONG THE
IMMEDIATE COAST. RUC ANALYSIS SHOWS THE THERMAL TROUGH TO BE A BIT
WEAKER AND ORIENTED FURTHER INLAND...ALLOWING THE NORTHERLY FLOW TO
RETURN TO THE MENDOCINO COAST AND KEEP ANY STRATUS WELL TO THE SOUTH
OR FURTHER OFFSHORE. MEANWHILE ENOUGH OFFSHORE FLOW STILL EXISTS
CLOSER TO THE SFC RIDGE AXIS IN SOUTHERN OREGON TO KEEP CRESCENT
CITY MOSTLY CLEAR. EXPECT THE STRATUS TO ERODE THIS AFTERNOON AS
BOUNDARY LAYER NORTHERLY WINDS INCREASE. EXPECT SIMILAR CONDITIONS
TONIGHT WITH EVEN MORE BOUNDARY LAYER MOISTURE AND A STRONGER
INVERSION AS THE RIDGE PUSHES CLOSER TO THE WEST COAST. UPPER LEVEL
RIDGING WILL CONTINUE TO PUSH EASTWARD TOWARD THE WEST COAST ON
THURSDAY AND THE RIDGE AXIS WILL PASS BY FRIDAY MORNING. THIS WILL
ALLOW HIGH PRESSURE BOTH AT THE SFC AND ALOFT TO BUILD OVER THE
PACIFIC NORTHWEST AND EVENTUALLY THE GREAT BASIN...WHILE THE THERMAL
TROUGH PUSHES WESTWARD OFF THE COAST. INCREASING OFFSHORE FLOW WILL
RESULT LATER THURSDAY INTO FRIDAY WITH CLEAR SKIES AND LIGHT WINDS
ACCOMPANIED BY ABOVE NORMAL TEMPERATURES. EVEN THE IMMEDIATE COAST
WILL REACH 60 DEGREES WITH 70S ACROSS THE INTERIOR VALLEYS. AAD
.LONG TERM...
BY SATURDAY AFTERNOON ONSHORE FLOW WILL RETURN WITH BOUNDARY LAYER
MOISTURE INCREASING AGAIN AT THE COAST. TEMPERATURES WILL BEGIN TO
COOL WITH INCREASING CLOUD COVER...ALONG WITH A SLIGHT CHANCE OF
SHOWERS. MODELS DO NOT SHOW ANY MEASURABLE RAINFALL SOUTH OF THE
OREGON BORDER AS MOISTURE WILL BE VERY LIMITED. AS SUCH DO NOT
EXPECT MORE THAN A SHOWER OR TWO IN THE LIMITED FORCING ALONG THE
WEAKENING COLD FRONT. MAY NEED TO ADD FOG AND DRIZZLE OVERNIGHT INTO
SUNDAY MORNING WITH THE ONSHORE PUSH OF BOUNDARY LAYER MOISTURE. BY
SUNDAY THE AIRMASS WILL DRY OUT WITH NORTHERLY FLOW RETURNING AS
HIGH PRESSURE BUILDS BACK OVER THE EASTERN PACIFIC. A MORE
SIGNIFICANT SYSTEM WILL APPROACH BY MONDAY NIGHT IN THE FORM OF AN
UPPER LEVEL LOW DROPPING SOUTHEASTWARD FROM THE GULF OF ALASKA.
ALTHOUGH MODELS ARE SIMILAR IN THE GENERAL PATTERN NEXT WEEK THERE
ARE SOME SIGNIFICANT DIFFERENCES WITH RESPECT TO THE DETAILS. HAVE
OPTED TO RAISE POPS TO AROUND DOUBLE CLIMO AS THERE IS HIGH
CONFIDENCE IN A PERIOD OF SHOWERS AND MOUNTAIN SNOW CENTERED AROUND
TUESDAY. THAT SAID PRECIPITATION AMOUNTS AND THE DEGREE OF COLD AIR
WITH THE SYSTEM ARE VERY MUCH UP IN THE AIR. AAD
&&
.AVIATION...11-4U SAT IMAGERY SHOWS OFFSHORE FLOW RESULTING IN
CLEARING STRATUS N OF TRINIDAD. PATCHY FG N OF TRINIDAD WILL RESULT
IN MVFR VSBYS/IFR CIGS THROUGH 17Z. GREATER ONSHORE COMPONENT S OF
TRINIDAD WILL RESULT IN IFR TO MVFR CIGS AROUND HUMBOLDT BAY AND THE
EEL RIVER VALLEY INTO NRN MENDO COUNTY THROUGH 20Z. VFR CONDITIONS
WILL PERSIST THROUGH THE AFTERNOON THEN DETERIORATE THIS EVENING.
STRATUS/FG WILL IMPACT AREAS AROUND HUMBOLDT BAY AS EARLY AS 14/00Z
WITH IFR CONDITIONS EXPANDING ALONG THE COAST AND INLAND
OVERNIGHT.
&&
.MARINE...BUOY OBS SHOW NLY WINDS REMAINING AROUND 20 KT N OF CAPE
MENDO WITH SEAS AROUND 10 FT. WINDS WILL INCREASE AGAIN THIS
AFTERNOON THEN DECREASE LATE THU. LONG PERIOD WAVE GROUP WILL
CONTINUE TO DECAY THIS MORNING WITH FORERUNNERS FROM ANOTHER WAVE
GROUP BUILDING INTO THE WATERS THIS AFTERNOON/EVENING. A 3RD WAVE
TRAIN WILL ARRIVE LATE FRI/EARLY SAT AND PERSIST THROUGH THE
WEEKEND.
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 9 PM PST THURSDAY PZZ450.
SMALL CRAFT ADVISORY UNTIL 9 AM PST FRIDAY PZZ470.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 3 PM PST THURSDAY
PZZ455.
SMALL CRAFT ADVISORY UNTIL 3 AM PST FRIDAY PZZ475.
&&
$$
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AREA FORECAST DISCUSSION...UPDATED
NWS PUEBLO CO
555 PM MST THU FEB 14 2013
.UPDATE...
ISSUED AT 546 PM MST THU FEB 14 2013
ADJUSTED POPS TO REDUCE COVERAGE OF SNOW ACROSS THE SOUTHEAST MTS/PLAINS.
GREATEST COVERAGE FOR THE NEXT COUPLE HOURS WILL BE ACROSS THE
LOWER EASTERN SLOPES OF THE SANGRES/WETS AND SRN I-25 CORRIDOR.
TREND WILL BE FOR WINDS TO SHIFT OUT OF THE SOUTHEAST WITH SOME
ISOLATED TO SCATTERED SNOW SHOWERS POSSIBLE ACROSS PORTIONS OF
SOUTHERN EL PASO COUNTY. DOESN`T APPEAR SNOWFALL WILL AMOUNT TO
MUCH WITH MOST AMOUNTS STAYING WELL UNDER 1 INCH. LATEST HIGH RES
MODELS REALLY DIMINISH PCPN QUICKLY TOWARDS 06Z. CURRENT GRIDS
ALREADY HAD THIS TREND WELL DEPICTED SO MAIN CHANGE WAS TO THE
FIRST 3 HOURS. -KT
&&
.SHORT TERM...(TONIGHT AND TOMORROW)
ISSUED AT 308 PM MST THU FEB 14 2013
A FAST MOVING COLD FRONT HAS MOVED SOUTH OF HIGHWAY 50. THE FRONT
SHOULD CLEAR THE CO/NM BORDER BY 22Z. THE HRRR AND RAP PROG ANY
LINGERING SNOW SHOWERS TO END BY MIDNIGHT ACROSS THE AREA.
HOWEVER...THE NAM12 AND GFS ARE HOLDING ON TO SNOW SHOWERS
THROUGH 12Z ACROSS THE SOUTHERN I-25 CORRIDOR. DECIDED TO LEAVE
SOME 15 TO 35 POPS SOUTH AND WEST OF TAD IN THE GRIDS. DUE TO TO
THE FAST MOVEMENT OF THE FRONT/PRECIP...LITTLE TO NO ACCUMULATIONS
ARE EXPECTED UNDER ANY OF THE SNOW SHOWERS EAST OF THE CONTINENTAL
DIVIDE. GUSTY NORTHEAST WINDS WILL BEGIN TO RELAX AFTER 02Z. WEST
OF THE I-25 CORRIDOR...LIGHT SNOW SHOWERS WILL CONTINUE IN AND
AROUND THE LEADVILLE AREA OVERNIGHT INTO TOMORROW MORNING. THE
SAN LUIS VALLEY WILL BE MOSTLY CLEAR...COLD...AND DRY OVERNIGHT
FRIDAY...MODELS CONTINUE TO SHOW LIGHT SNOW SHOWERS IN THE LEADVILLE
AREA THROUGH FRIDAY AFTERNOON AND HAVE KEPT POPS IN PLACE AS PREVIOUSLY
FORECASTED. 700MB TEMPERATURES WILL FALLING TO -11 TO -13.5C WILL
KEEP HIGH TEMPERATURES 3-5 DEGREES COOLER ACROSS MOST LOCATIONS
FRIDAY AFTERNOON. A FEW LINGERING CLOUDS ACROSS THE AREA WILL ALSO
HELP TO CAP HIGH TEMPERATURES TOMORROW AFTERNOON. -PJC
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 308 PM MST THU FEB 14 2013
(FRIDAY NIGHT-THURSDAY)
FRIDAY NIGHT-SUNDAY...STRONG NORTH TO NORTHWEST FLOW ALOFT ACROSS
THE REGION FRIDAY NIGHT MODERATES AND BECOMES MORE WESTERLY THROUGH
THE DAY SUNDAY AS UPPER LEVEL RIDGING BUILDING ACROSS THE GREAT
BASIN FLATTENS ACROSS THE STATE AHEAD OF MORE SHORT WAVE ENERGY
MOVING ONSHORE ACROSS THE PAC NORTHWEST COAST. DRY WEATHER WITH WELL
ABOVE SEASONAL TEMPERATURES EXPECTED THROUGH THE FIRST PART OF THE
HOLIDAY WEEKEND...WITH BREEZY WEST WINDS ACROSS THE HIGHER TERRAIN
AND IMMEDIATE ADJACENT PLAINS SATURDAY AND SATURDAY NIGHT. SHOULD
SEE INCREASING HIGH CLOUDS FROM WEST TO EAST THROUGH THE DAY SUNDAY
AS THE SYSTEM CONTINUES TO MOVE ACROSS THE GREAT BASIN.
SUNDAY NIGHT-MONDAY NIGHT...STILL SOME MODEL DIFFERENCES ON AMPLITUDE
OF GREAT BASIN SYSTEM MOVING ACROSS THE ROCKIES WITH THE 12Z GFS
STILL DIGGING FURTHER SOUTH THAN THE ECMWF...HOWEVER THE GFS HAS
STARTED TO TREND FURTHER NORTH AND IS WEAKER WITH THE SYSTEM THAN
PREVIOUS RUNS. WITH THAT SAID...SHOULD STILL SEE A HEALTHY COLD
FRONT WITH A 10-20 DEGREE DROP IN TEMPERATURES FROM SUNDAY...MOST
NOTICEABLE ACROSS EASTERN COLORADO. HAVE ALSO KEPT ISOLATED TO
SCATTERED POPS INTACT ACROSS THE HIGHER TERRAIN AND IMMEDIATE
ADJACENT PLAINS...WITH NOT MUCH PRECIPITATION EXPECTED...ESPECIALLY
IF THE SYSTEM CONTINUES TO TREND FURTHER NORTH.
TUESDAY-THURSDAY...WARMER WESTERLY FLOW PROGGED ACROSS THE AREA
TUESDAY WITH INCREASING SOUTHWEST FLOW TUESDAY NIGHT AND WEDNESDAY
AHEAD OF A STRONGER SYSTEM MOVING INTO THE GREAT BASIN. SOME
DIFFERENCES IN MOVEMENT OF THIS SYSTEM WITH THE GFS LIFTING IT
ACROSS SOUTH CENTRAL COLORADO WEDNESDAY NIGHT AND INTO THE NORTHWEST
KANSAS ON THURSDAY. THE LATEST EC IS A TAD FURTHER SOUTH WITH THE
SYSTEM ACROSS SOUTHWEST KANSAS ON THURSDAY...WHICH PRODUCES BETTER
CHANCES OF SNOW AND BLOWING SNOW ACROSS THE SOUTHEAST PLAINS NORTH
OF HIGHWAY 50...ESPECIALLY AREAS ALONG THE PALMER DVD. AT ANY
RATE...MODEL CONSENSUS IS FAIRLY CONSERVATIVE THIS FAR OUT AND
HAVE INCREASED POPS TO CHANCES ALONG THE CONTDVD FOR THE WEDNESDAY
THROUGH EARLY THURSDAY PERIODS. HAVE ALSO INCREASED POPS TO SLIGHT
CHANCES ACROSS PORTIONS OF THE PLAINS. THIS SYSTEM WILL LIKELY
PRODUCE SIGNIFICANT WEATHER SOMEWHERE ACROSS THE REGION...THOUGH
TIME WILL TELL AS TO EXACTLY WHERE. -MW
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 308 PM MST THU FEB 14 2013
VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES...KALS...KCOS...AND
KPUB THROUGH TOMORROW AFTERNOON WITH AN OCCASIONAL DROP TO MVFR
CONDITIONS AT KCOS EARLY THIS EVENING DUE TO LIGHT SNOW SHOWER
ACTIVITY IN THE AREA. GUSTY WINDS FROM THE NORTH AND NORTHEAST
WILL DIMINISH LATER THIS EVENING. -PJC
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TORGERSON
SHORT TERM...PJC
LONG TERM...MW
AVIATION...PJC
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
345 PM MST WED FEB 13 2013
.SHORT TERM...MODERATE NORTHWEST FLOW ALOFT ACROSS REGION. AIRMASS
FAIRLY MOIST BUT RELATIVELY STABLE. MOUNTAIN WEB CAMS SHOWING SOME
LIGHT SNOW ALONG THE CONTINENTAL DIVIDE AS THE PARK AND GORE
RANGES OF WESTERN JACKSON COUNTY. LATEST SNOTEL DATA SUGGESTING
SOME LIGHT ACCUMULATIONS IN ZONE 31 AND PORTIONS OF ZONES 33 AND
34. WINDS HAVE BEEN A BIT GUSTY ACROSS THE HIGHER RIDGES AND ALONG
THE FOOTHILLS. WEST TO NORTHWEST WINDS HAVE ALSO SPREAD ONTO THE
ADJACENT PLAINS AS WELL AS ALONG THE WYOMING AND NEBRASKA BORDERS.
LATEST RAP SHOWS MOISTURE GRADUALLY INCREASING AS LAPSE RATES
INCREASE TO AROUND 7 C/KM BY MIDNIGHT. SHOULD SEE THE SNOW
INCREASE IN COVERAGE OVERNIGHT DUE TO FAVORABLE OROGRAPHICS AND
LAPSE RATES...MAINLY NORTH OF INTERSTATE 70. THERE IS ALSO SOME
INCREASE IN MID LEVEL QG ASCENT AHEAD OF AN APPROACHING SHORTWAVE
WHICH WILL HELP WITH SNOWFALL. SNOW ACCUMULATIONS SHOULD REMAIN
BELOW ADVISORY CRITERIA. ACROSS FOOTHILLS AND PLAINS...GRADIENT
WEAKENS DURING THE EVENING. SHOULD SEE WINDS DECREASE AS A
RESULT...WITH DRAINAGE PATTERN PREVAILING. ON THURSDAY...NORTHWEST
FLOW ALOFT TO CONTINUE. MODELS CONTINUE TO SHOW WEAK SHORTWAVE
MOVING ACROSS WYOMING DURING THE AFTERNOON WITH MID LEVEL ASCENT
MOVING OVER THE AREA. LIGHT SNOW TO BE MORE WIDESPREAD OVER THE
MOUNTAINS SOUTH OF INTERSTATE 70 BY THE AFTERNOON AS OROGRAPHICS
REMAINS FAVORABLE. MODEL CROSS SECTIONS INDICATE VARYING AMOUNTS
OF MOISTURE WITH THE GFS DEEPEST. WILL INCREASE THE POPS AND
COVERAGE OF THE SNOW A BIT BUT KEEP AMOUNTS BELOW ADVISORY
CRITERIA. ACROSS PLAINS...MODELS CONTINUE TO SHOW A FRONT MOVING
SOUTH ACROSS THE AREA DURING THE MORNING...REACHING DENVER AREA
AROUND 15-18Z. NORTHERLY WINDS WITH FRONT BECOMES NORTHEAST DURING
THE AFTERNOON AS SURFACE HIGH PUSHES IN BEHIND FRONT. UPSLOPE NOT
ALL THAT DEEP ACCORDING TO THE CROSS SECTIONS BUT DOES REACH THE
FOOTHILLS. MODELS DO INDICATE SOME LIGHT QPF IN AND NEAR FOOTHILLS
DURING THE AFTERNOON WHEN THE UPSLOPE FLOW OCCURS AND LIFT IS
OVERHEAD. MODEL CONCENSUS SHOWING SNOW AMOUNTS TO BE LESS THAN AN
INCH AND CONFINED TO FOOTHILL AREAS. GFS CONTINUES TO BE
AGRESSIVE WITH THE QPF AND SNOW AMOUNTS. WILL CONTINUE WITH THE
CHANCE POPS FOR THE AFTERNOON MOST AREAS...WITH LIKELY POPS FOR
THE FOOTHILLS. TEMPERATURES TO BE COOLER WITH HIGHS IN THE LOWER
TO MID 30S ACROSS THE PLAINS.
.LONG TERM...NORTHWEST FLOW ALOFT WILL PREVAIL THURSDAY NIGHT AND
FRIDAY WHILE NORTHERLY FLOW EXISTS AT THE LOWER LEVELS.
MOISTURE...LIFT AND INSTABILITY WILL BE LIMITED...BUT ENOUGH WILL
BE PRESENT FOR OCCASIONAL LIGHT SNOW. A WEAK SHORT WILL MOVE
ACROSS THE STATE FRIDAY. IN ADDITION...THE FRONT LEFT QUADRANT OF
THE JET WILL BE OVER NORTHEAST COLORADO FRIDAY. THESE FEATURES
WILL PROVIDE THE LIFT FOR THE LIGHT SNOW. SNOW WILL COME TO END BY
FRIDAY EVENING...IF NOT SOONER AS DRIER AIR SHIFTS OVER THE STATE.
UPPER LEVEL RIDGE WILL MOVE OVER COLORADO SATURDAY. AN UPPER LEVEL
TROUGH WILL DROP INTO THE NORTHERN ROCKIES SUNDAY CAUSING FLOW ALOFT
TO BECOME WESTERLY ON SUNDAY. THIS WILL RESULT IN MILD AND DRY
CONDITIONS FOR THE WEEKEND WITH HIGHS IN THE 50S ACROSS NORTHEAST
COLORADO.
FOR SUNDAY NIGHT AND MONDAY...THE SHORT WAVE TROUGH OVER THE
NORTHERN ROCKIES MAY BRING THE AREA A ROUND OF SNOW AS IT PROGRESSES
EAST. THE GFS BRINGS A PIECE OF ENERGY THROUGH UTAH AND THEN DROPS
IT SOUTHEAST INTO NEW MEXICO. THE ECMWF KEEPS THIS SYSTEM NORTH OF
COLORADO WHICH WOULD RESULT IN DRY CONDITIONS. THE CMC IS SIMILAR TO
THE ECMWF SO WILL KEEP POPS ON THE LOW END FOR THIS SYSTEM. STILL
EXPECT A COLD FRONT AND COOLER AIR TO PUSH THROUGH COLORADO IF THIS
SYSTEMS STAYS NORTH OF THE STATE.
UPPER LEVEL RIDGE WILL QUICKLY MOVE ACROSS THE STATE MONDAY NIGHT
AND BY TUESDAY A SOUTHWEST FLOW ALOFT WILL PREVAIL AS A LARGE TROUGH
CRASHES ONTO THE WEST COAST. THIS SYSTEM WILL SLOWLY MOVE EASTWARD
WEDNESDAY. EXPECT MILD AND DRY CONDITIONS TO PREVAIL WEDNESDAY AHEAD
OF THIS SYSTEM. MAY BE ENOUGH MOISTURE AHEAD OF IT TO PRODUCE LIGHT
MOUNTAIN SNOW. LOOKING BEYOND THE FORECAST TIME FRAME...THE PAST TWO
RUNS OF THE ECMWF SHOW THIS TROUGH MOVING ALONG THE COLORADO/NEW
MEXICO BORDER. IF THIS TYPE OF PATTERN PREVAILS...EASTERN COLORADO
COULD SEE A GOOD SHOT OF SNOW.
&&
.AVIATION...WEST TO NORTHWEST WINDS HAVE PUSHED ACROSS THE AREA
AIRPORTS DURING THE AFTERNOON...WITH GUSTS AROUND 35 KTS AT APA
AND BJC. WINDS SHOWING MORE OF A WESTERLY COMPONENT IN THE PAST
HOUR. MODELS SHOW WINDS WEAKENING BY 01Z AND BECOMING MORE
SOUTHWEST AS DRAINAGE FLOW DEVELOPS. MID AND HIGH LEVEL LEVEL
MOISTURE TO INCREASE OVERNIGHT...CEILINGS TO REMAIN ABOVE 10000
FEET. ON THURSDAY...FRONT TO MOVE ACROSS THE AREA AROUND 15Z WITH
WINDS SHIFTING TO THE NORTH. COULD SEE SOME GUSTS TO 30 KTS.
CEILINGS EXPECTED TO LOWER TO AROUND 6000 FEET AGL BY 18Z. A FEW
SNOW SHOWERS COULD DEVELOP DURING THE MORNING...MAINLY WESTERN
SUBURBS. NORTHEAST WINDS DEVELOP AFTER 18Z WITH MVFR CEILINGS
POSSIBLE. THERE WILL BE A CHANCE OF LIGHT SNOW DURING THE
AFTERNOON...FOR NOW WILL WILL MAINTAIN A PROB30. ANY ACCUMULATIONS
SHOULD BE LESS THAN AN INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1009 AM MST WED FEB 13 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS LOOK REASONABLE. MOUNTAIN WEB
CAMS INDICATING SOME LIGHT SNOW OVER THE HIGHER PEAKS OF SUMMIT...
GRAND AND BOULDER COUNTIES...WITH PERHAPS SOME LIGHT SNOW ACROSS
THE PARK AND GORE RANGES OF WESTERN JACKSON COUNTY. WINDS HAVE
BEEN STEADILY INCREASING ACROSS THE HIGHER MOUNTAINS AND FOOTHILLS...
LATEST 1500 MB GJT-DEN PRESSURE GRADIENT HAD INCREASED TO 10.40 MB.
GUSTS WERE MAINLY IN THE 40-50 MPH RANGE ALONG THE FOOTHILLS OF
BOULDER...JEFFERSON AND LARIMER COUNTIES. LATEST RAP CROSS SECTIONS
INDICATE CROSS MOUNTAIN FLOW AROUND 35 KTS ALONG WITH A WEAK STABLE
LAYER NEAR THE MOUNTAIN TOP THROUGH THE AFTERNOON. AT THIS TIME...
NOT EXPECTING WINDS TO REACH HIGH WIND CRITERIA. COVERAGE OF SNOW
TO INCREASE AFTER MIDNIGHT WHEN LAPSE RATES INCREASE AND OROGRAPHICS
BECOME MORE FAVORABLE.
.AVIATION...WESTERLIES SLOW TO PUSH INTO THE DENVER AREA...FINALLY
REACHED BJC. RECENTLY DELAYED THE ONSET OF THE WEST WINDS AT DEN
TIL 19Z. THIS STILL SEEMS ON TRACK AS LATEST DEN LLWAS DATA
CONTINUES TO INDICATE MORE OF A SOUTHWEST DIRECTION. LATEST RAP
AND HRRR SHOW WINDS BECOMING NORTHWEST AT DEN AND APA BY 21Z. SO
TREND FOR NORTHWEST WINDS STILL LOOKS REASONABLE...BUT WILL DELAY
THE ONSET FOR THE UPCOMING ISSUANCE. REST OF TAF TRENDS SEEM
REASONABLE...WITH SOUTH TO SOUTHWEST DRAIANGE WINDS DEVELOPING
DURING THE EVENING. COLD FRONT STILL ON TRACK TO MOVE ACROSS THE
AREA AIRPORTS AROUND 15Z THURSDAY...WITH NORTHEAST WINDS
DEVELOPING ALONG WITH LOWER CEILINGS. WILL INCLUDE A PROB30 AT DEN
AFTER 19Z WITH MVFR CEILINGS.
&&
.PREV DISCUSSION... /ISSUED 301 AM MST WED FEB 13 2013/
SHORT TERM...NW FLOW ALOFT WILL INCREASE OVER THE AREA THRU
TONIGHT WITH MOISTURE GRADUALLY INCREASING IN THE MTNS. ALTHOUGH
OROGRAPHIC FLOW WILL BE FAVORABLE LAPSE RATES INITIALLY ARE RATHER
STABLE AND REALLY DO NOT BEGIN TO INCREASE UNTIL AFTER MIDNIGHT.
THUS EXPECT AREAS OF LIGHT SNOW IN THE MTNS MAINLY NORTH OF I-70
WITH SOME INCREASE IN COVERAGE TONIGHT. OVERALL AMOUNTS AT LEAST
THRU TONIGHT STAY BLO ADVISORY CRITERIA. MEANWHILE WITH MTN TOP
STABILITY THRU THE AFTN HOURS WILL SEE GUSTY WINDS OVER THE HIGHER
MTNS AND IN AND NR THE FOOTHILLS. COMPONENT ALONG SPEEDS ARE ON
AVERAGE AROUND 35KTS SO SPEEDS SHOULD STAY BLO HIGH WIND
CRITERIA. WILL ALSO SEE GUSTY WINDS NR THE WY-NE BORDER AS WELL
THRU THE AFTN HOURS. AS FOR TEMPS OVER NERN CO WILL HAVE HIGHS IN
THE 45 TO 50 DEGREE RANGE.
LONG TERM...MODELS HAVE FAIRLY STRONG WEST-NORTHWESTERLY FLOW
ALOFT FOR THE CWA THURSDAY. BY LATE IN THE DAY A WEAK UPPER
TROUGH PUSHES ACROSS WITH STRONG NORTH-NORTHWESTERLY FLOW ALOFT
BEHIND IT. THE STRONG FLOW ALOFT IS PROGGED TO CONTINUE ON
FRIDAY...BUT TO BECOME NORTHERLY IN DIRECTION. THE FLOW ALOFT
BECOMES NORTHWESTERLY AND RELAXES SOMEWHAT BY 12Z SATURDAY
MORNING. THE QG VERTICAL VELOCITY FIELDS SHOW WEAK UPWARD ENERGY
THURSDAY...FOLLOWED BY DOWNWARD MOTION LATE DAY INTO THE
EVENING...THEN ANOTHER BRIEF SHOT OF UPWARD MOTION THROUGH 12Z
FRIDAY MORNING. AFTER THAT IT IS ALL DOWNWARD MOTION INTO THE
WEEKEND. THE UPWARD MOTION LOOKED BETTER ON YESTERDAY`S 00Z RUNS.
THE BOUNDARY LAYER FLOW PROGGS STILL SHOW A BIT OF UPSLOPE OVER
THE PLAINS ON THURSDAY...BUT IT IS GONE THURSDAY NIGHT. BY FRIDAY
MORNING...DOWNSLOPING NORTHWESTERLY FLOW IS PROGGED CONTINUING
THROUGH FRIDAY NIGHT. AGAIN...YESTERDAY`S 00Z RUNS HAD BETTER AND
MORE PROLONGED UPSLOPE FOR PLAINS AND FOOTHILLS. MOISTURE IS ALSO
LESS ACCORDING TO THE CURRENT MODEL RUNS...ESPECIALLY ON THE NAM.
THERE IS SOME MOISTURE AROUND ON THE NAM THURSDAY...BUT IT DECREASES
PRETTY GOOD THURSDAY EVENING. IT INCREASES AGAIN BY 12Z FRIDAY
MORNING...THEN GRADUALLY DECREASES THROUGH THE DAY FRIDAY. THE
GFS HAS A SIMILAR PATTERN ALTHOUGH THE DEPTH OF MOISTURE IS
GREATER THAN ON THE NAM. THE ECMWF IS SOMEWHERE IN BETWEEN THE
TWO. FRIDAY NIGHT DRIES OUT PRETTY GOOD ON ALL THE MODELS. THE QPF
FIELDS SHOW MEASURABLE SNOWFALL FOR THE CWA THURSDAY INTO FRIDAY.
IT IS LESS THAN YESTERDAY`S RUNS INDICATED AND IT IS MOSTLY OVER
THE THE MOUNTAINS. AMOUNTS ARE PRETTY WEAK. SO FOR POPS IN THE
MOUNTAINS...THERE WILL BE SOME OROGRAPHIC HELP AND THERE IS SOME
MOISTURE...SO WILL GO WITH "LIKELY"S THURSDAY AND THURSDAY
NIGHT...THEN DECREASE POPS TO NOTHING DURING THE EVENING FRIDAY.
FOR THE PLAINS...10-40%S SHOULD THURSDAY AFTERNOON INTO MIDDAY
FRIDAY. ACCUMULATIONS IN THE MOUNTAINS LOOK TO BE UNDER ADVISORY
AMOUNTS. FOR TEMPERATURES...THURSDAY`S HIGHS SHOULD BE 4-8 C
COLDER THAN TODAY`S HIGHS. FRIDAY`S HIGHS ARE 0-3 C WARMER THAN
THURSDAY`S. FOR THE LATER DAY`S...SATURDAY THROUGH TUESDAY...
MODELS HAVE DECREASING NORTHWESTERLY FLOW ALOFT ON SATURDAY AS AN
UPPER RIDGE MOVES IN AND ACROSS THE CWA BY SUNDAY. THE NEXT UPPER
TROUGH GETS INTO WESTERN COLORADO BY 12Z MONDAY AND ACROSS THE CWA
BY EARLY MONDAY EVENING. DECREASING NORTHWESTERLY FLOW ALOFT
MONDAY NIGHT GIVES WAY TO ANOTHER UPPER RIDGE ON TUESDAY. THE LATE
SUNDAY NIGHT THROUGH LATE MONDAY TROUGH LOOKS TO HAVE OK MOISTURE
..FAIR COLD AIR...AND UPSLOPE FOR THE PLAINS AND FOOTHILLS.
WE`LL SEE.
AVIATION...EARLY THIS MORNING WINDS WERE DRAINAGE WITH A BKN DECK
AROUND 9000 FT. SATELLITE ALREADY SHOWS THIS BKN DECK MOVING SE SO
SKIES SHOULD ONLY SEE SOME HIGHER CLOUDS. BY LATE THIS MORNING
INTO THE EARLY AFTN THE GUSTY WNW WINDS NR THE FOOTHILLS LOOK LIKE
THEY WILL GRADUALLY SPREAD ACROSS THE AIRPORT WITH SOME GUSTS TO
20-25 POSSIBLE FM 19Z-23Z BEFORE DECREASING. BY EARLY THIS EVENING
WILL KEEP THEM MORE WSW AND THEN SSW BY 06Z. WILL SEE SOME HIGHER
LEVEL CLOUD COVER THIS AFTN AND TONIGHT BUT NOTHING BLO 20000 FT.
A CDFNT WILL MOVE INTO THE AREA BY 15Z ON THU WITH WINDS BECOMING
NNE ALONG WITH LOWER CEILINGS DEVELOPING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
430 AM EST WED FEB 13 2013
.SYNOPSIS...
09Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING AN UPPER LEVEL PATTERN
CONSISTING OF BROAD RIDGING ALONG THE PACIFIC COAST FOLLOWED
DOWNSTREAM BY BROAD LONGWAVE TROUGHING ACROSS THE CENTRAL PORTION OF
THE COUNTRY. A STRONGER IMPULSE/SHORTWAVE IS EMBEDDED WITHIN THIS
TROUGH OVER THE CENTRAL/SOUTHERN PLAINS AND IS NOW QUICKLY EJECTING
EASTWARD TOWARD THE TN VALLEY AND SOUTHEASTERN STATES. OUR LOCAL
AREA RESIDES WITHIN A ZONES OF DEEP SOUTHWEST TO NORTHEAST MOISTURE
TRANSPORT BETWEEN THIS LONGWAVE TROUGH...AND A BROAD RIDGE OVER
THE WESTERN CARIBBEAN/FL STRAITS.
AT THE SURFACE...FL PENINSULA RESIDES WITH THE WARM SECTOR BETWEEN A
SYNOPTIC LOW OVER SOUTHERN AL...AND A SURFACE RIDGE ACROSS THE FL
STRAITS. SURFACE WARM FRONT EXTENDS EASTWARD FROM THE LOW ACROSS
SOUTHERN GA EARLY THIS MORNING WITH A TRAILING COLD FRONT MOVING
EASTWARD ACROSS THE CENTRAL GULF OF MEXICO. THIS FRONT WILL ARRIVE
OVER OUR REGION LATER TODAY AND TONIGHT. SEEING QUITE A BIT OF LOW
CLOUDS AND PATCHY FOG THIS MORNING WITHIN THE DEEP SOUTHERLY
MOISTURE TRANSPORT. THE BIGGEST CONCENTRATION OF THESE LOWER CLOUDS
IS COMING OFF THE GULF AS THE HIGHER DEWPOINT AIR INTERACTS WITH THE
COOLER SHELF WATERS...ESPECIALLY FROM WEST OF TAMPA BAY UP ALONG THE
NATURE COAST. DIFFICULT TO DETERMINE IF WE ARE DEALING WITH LOWER
STRATUS OR FOG OUT OF THE MARINE AREA...AS WE HAVE NOT SEEN MUCH
VISIBILITY REDUCTIONS AT ANY OF THE COASTAL STATIONS. IF
VERIFICATION ARRIVES THAT VISIBILITIES ARE SIGNIFICANTLY REDUCED
OVER THE MARINE AREA...THEN A DENSE FOG ADVISORY MAY BECOME
NECESSARY LATER THIS MORNING. REGIONAL RADARS SHOWS SHOWERS AND
STORM ONGOING ACROSS THE FL PANHANDLE/WESTERN BIG BEND WITHIN A
BROAD SWATH OF LOW LEVEL MOISTURE TRANSPORT/THETA-E ADVECTION.
&&
.SHORT TERM (TODAY THROUGH FRIDAY)...
TODAY/TONIGHT...
STRONG MID-LEVEL SHORTWAVE AND ASSOCIATED SURFACE LOW WILL PASS TO
OUR NORTH THROUGH THIS EVENING WHILE A COLD FRONT TRAILING SOUTH
FROM THE LOW APPROACHES FROM THE EASTERN GULF OF MEXICO. BROAD
SYNOPTIC FORCING ASSOCIATED WITH THE PASSING ENERGY ALONG WITH THE
LOW LEVEL FORCING AHEAD OF THE FRONT WILL BE ENOUGH TO SUPPORT A
BAND OF SHOWERS AND STORMS. THIS BAND IS FORECAST TO SHIFT SOUTH
AND SOUTHEAST WITH TIME FROM THE NATURE COAST LATER THIS MORNING AND
AFTERNOON....THROUGH THE TAMPA BAY/I-4 CORRIDOR DURING THE AFTERNOON
AND EARLY EVENING...AND THEN FURTHER SOUTH LATE IN THE DAY/EVENING.
LOW LEVEL WAA REGION/THETA-E ADVECTION AHEAD OF THE FRONT LOOKS TO
SLOWLY DIMINISH THROUGH THE DAY...ALONG WITH AN EVENTUAL WEAKENING
OF THE OVERALL KINEMATICS. WITH ALL THIS IN MIND...THE MOST
ORGANIZED BAND OF CONVECTION SHOULD OCCUR AS THE ACTIVITY IS
CROSSING THE NORTHERN AND CENTRAL PORTION OF THE FORECAST
AREA...WITH WEAKER AND MORE BROKEN CONVECTION ACROSS THE SOUTH. POPS
WILL FOLLOW TODAY WITH LIKELY TO CATEGORICAL VALUES NORTH AND THEN
DECREASING TO CHANCE/SLIGHT CHANCE POPS SOUTH AND SOUTHEAST FROM
TAMPA BAY. WILL CONTINUE TO MONITOR THE CHANCE OF A FEW STRONGER
STORMS...ACROSS THE NATURE COAST THROUGH THE EARLY AFTERNOON WITH
ISOLATED STRONG WIND GUSTS THE MAIN THREAT WITH ANY OF THE MORE
VIGOROUS CELLS. DEPARTING LOW LEVEL JET SHOULD FURTHER DECREASE ANY
WIND THREAT BY LATER IN THE DAY. A SLOW COOL DOWN BEGIN OVERNIGHT AS
WINDS SHIFT TO THE NORTH BEHIND THE FRONT. BROAD RESIDUAL SYNOPTIC
FLOW AND PLENTY OF LEFTOVER COLUMN MOISTURE MAY STILL SQUEEZE OUT A
FEW SHOWERS...BUT COVERAGE AND INTENSITY WILL BE LOW.
THURSDAY THROUGH FRIDAY...
LOWER CONFIDENCE FORECAST THAN NORMAL FOR THE SHORT TERM PERIOD WHEN
IT COMES TO THE DETAILS FOR THE FINAL TWO DAYS OF THE WORK WEEK. THE
REGION WILL BE LEFT WITHIN A BROAD CYCLONIC FLOW THAT WILL FEATURE
OCCASIONAL WEAKER IMPULSES PASSING THROUGH. THE COMBINATION OF THE
PERIODIC SYNOPTIC SUPPORT ASSOCIATED WITH THESE IMPULSES AND SEVERAL
FAVORABLE UPPER JET PLACEMENTS WILL FAVOR OFF AND ON PERIOD OF
COOL SHOWERS/RAIN. CERTAINLY NOT LOOKING FOR RAIN ALL THE TIME...BUT
WHEN THE INGREDIENTS COME TOGETHER WE CAN EXPECT SEVERAL SURGES
OF SHOWERS TO CROSS THE PENINSULA. IT IS THE EXACTLY WHERE AND WHEN
THAT MAKE THIS FORECAST DIFFICULT. VARYING SOLUTIONS ARE POSED BY
THE VARIOUS GUIDANCE MEMBERS...ALL SHOWING THIS OFF AND ON
ACTIVITY...BUT WITH UNIQUE PATTERNS. OVERALL IT IS THE I-4
CORRIDOR AND SOUTHWARD THE WOULD SEEM TO BE IN LINE TO EXPERIENCE
THE MOST SHOWER ACTIVITY...BUT WILL KEEP CHANCE POPS GOING FURTHER
NORTH TO ACCOUNT FOR THE FORECAST UNCERTAINTY. TEMPERATURES WILL BE
COOLER THAN PREVIOUS DAYS...ESPECIALLY WHERE THE RAIN PATTERNS
EVENTUALLY SET UP. DRIER AIR FILTERING IN FROM THE NORTH IN THE
LOWER LEVELS WOULD COMBINE WITH THE RAIN TO PRODUCE POTENTIAL
WET-BULB EFFECT. HAVE GONE WITH A BLEND OF THE WARMER MAV AND COOLER
MET TEMPERATURES TO BEGIN THE TREND TOWARD POTENTIALLY COOLER END OF
THE WEEK TEMPS.
&&
.LONG TERM (FRIDAY NIGHT THROUGH NEXT TUESDAY)...
ALL MODELS SHOW A DEEPENING UPPER-LEVEL TROUGH SWINGING THROUGH THE
REGION OVER THE WEEKEND. THE GFS AND CANADIAN MODELS SHOW A MORE
PROGRESSIVE NATURE TO THE TROUGH WITH THE AXIS MOVING ACROSS THE
STATE SATURDAY NIGHT. THE ECMWF IS LAGGING BEHIND BY 12 TO 18 HOURS.
IN GENERAL...MODELS ARE FASTER NOW WITH THE TROUGH AND COLD AIR MASS
WHICH IN TURN MEANS THE COLD AIR WILL MOVE OUT NEARLY AS FAST AS IT
COMES IN.
LINGERING SHOWERS OVER OUR SOUTHERN ZONES FRIDAY NIGHT SHOULD COME
TO AN END BY SATURDAY MORNING FOLLOWED BY MUCH COOLER AIR AND
INCREASING NORTHWESTERLY WINDS. GENERALLY FOLLOWED LATEST MEX
GUIDANCE WHICH SHOWS TEMPERATURES HOLDING IN THE MIDDLE 60S EXCEPT
FOR OUR FAR SOUTHERN ZONES WHERE WE COULD STILL SEE SOME LOWER 70S.
WITH THE COLD AIR MASS COMING IN FASTER...IT NOW LOOKS LIKE OUR
COLDEST NIGHT WILL BE SATURDAY NIGHT...ALTHOUGH SUNDAY NIGHT COULD
STILL BE QUITE CHILLY. THE FASTER SOLUTION MEANS THE COLD HIGH
CENTER MOVES OUT INTO THE ATLANTIC MORE QUICKLY RESULTING IN A
RETURN FLOW FROM THE EAST. IT STILL LOOKS LIKE WE WILL SEE FREEZING
TEMPERATURES NORTH OF TAMPA BAY...BUT ON SUNDAY MORNING RATHER THAN
MONDAY MORNING.
SUNDAY SHOULD BE SUNNY AND COOL WITH WINDS SLOWLY DIMINISHING. HIGHS
WILL STAY IN THE 60S. SUNDAY NIGHT WILL BE COLD AGAIN...BUT DO NOT
EXPECT WIDESPREAD FREEZING TEMPERATURES ANYWHERE.
THE COLD HIGH WILL MOVE INTO THE ATLANTIC BY MONDAY PROVIDING A
RATHER QUICK WARMUP DURING THE DAY. HIGHS WILL BE ABOUT 8 DEGREES
WARMER THAN ON SUNDAY. BY TUESDAY...WE ARE BACK INTO THE MIDDLE 70S
TO NEAR 80...BUT A COLD FRONT WILL BE APPROACHING FROM THE NORTHWEST
SO THERE WILL BE A SLIGHT CHANCE OF SHOWERS NORTH OF TAMPA. THE
FRONT ON TUESDAY LOOKS LIKE ANOTHER MESSY ONE WITH RAIN CHANCES
EXTENDING INTO THE MIDDLE OF THE WEEK.
&&
.MARINE...
CAUTIONARY LEVEL WINDS OUT OF THE SOUTH WILL CONTINUE TODAY AHEAD OF
AN APPROACHING COLD FRONT. AREAS OF MARINE FOG WILL ALSO CONTINUE
ACROSS AREAS MAINLY OFFSHORE AND TO THE NORTH OF TAMPA BAY. THE COLD
FRONT WILL CROSS THE FORECAST WATERS THIS AFTERNOON AND THIS EVENING
WITH A WIND SHIFT TO THE NORTH IN ITS WAKE. WINDS WILL REMAIN FROM A
NORTHERLY DIRECTION THROUGH AT LEAST THE EARLY PORTION OF THE
UPCOMING WEEKEND AS HIGH PRESSURE SLOWLY BUILDS EAST TOWARD THE
REGION.
&&
.AVIATION...
AREAS OF LOW CLOUDS AND SOME FOG CONTINUE TO PLAGUE MOST OF THE TAF
SITES THIS MORNING. THERE ARE GAPS IN THE COVERAGE WHICH LEADS TO
PERIODS OF VFR CONDITIONS BETWEEN THE IFR TO EVEN LIFR CEILINGS.
VERY LOW CONFIDENCE IN THE FORECASTS FOR THE NEXT 24 HOURS...BUT IN
GENERAL LOOK FOR IMPROVING CONDITIONS BY LATE MORNING WITH MAINLY
MVFR CEILINGS. SOME SHOWERS AND STORMS WILL PRECEDE A FRONT LATER
THIS AFTERNOON.
&&
.FIRE WEATHER...
RELATIVE HUMIDITY VALUES WILL REMAIN WELL ABOVE CRITICAL LEVELS
TODAY AHEAD OF A COLD FRONT...HOWEVER GUSTY SOUTHWEST WINDS AND GOOD
DISPERSION INDICES CAN BE EXPECTED. SOME LOW LEVEL DRY AIR WILL
ATTEMPT TO FILTER IN FROM THE NORTH THE NEXT COUPLE OF DAYS BEHIND
THE FRONT...BUT THE PATTERN WILL SUPPORT A CONTINUED CHANCE OF
SHOWERS...AN NO CRITICAL LEVELS OF RELATIVE HUMIDITY ARE ANTICIPATED
THROUGH FRIDAY. UNLIKE TODAY...DISPERSION INDICES WILL BE QUITE LOW
FOR THURSDAY AND FRIDAY...LIKELY REMAINING BELOW 30 FOR MOST
LOCATIONS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 80 60 71 55 / 60 40 30 60
FMY 85 64 80 60 / 20 30 60 60
GIF 83 57 74 52 / 50 40 30 60
SRQ 78 59 73 58 / 50 40 40 60
BKV 80 54 71 48 / 70 30 20 60
SPG 80 61 71 58 / 60 40 30 60
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...BEACH HAZARDS STATEMENT THROUGH THURSDAY EVENING FOR
CHARLOTTE-LEE.
LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 6 PM EST
THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-
HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE-
PASCO-PINELLAS-POLK-SARASOTA-SUMTER.
BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR SARASOTA.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
226 PM EST WED FEB 13 2013
.SYNOPSIS...
LOW PRESSURE WILL BE LIFTING NORTHEAST OF THE FORECAST AREA THROUGH
TONIGHT. THE PRESSURE GRADIENT WILL RELAX AND WINDS WILL DIMINISH
TONIGHT AS THE LOW MOVES FARTHER AWAY. WEAK HIGH PRESSURE WILL
DOMINATE THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THIS AFTERNOON...LOW PRESSURE IS LIFTING NORTHEAST OF THE AREA.
THE PRESSURE GRADIENT ASSOCIATED WITH THIS LOW WILL BRING BREEZY
CONDITIONS. THE NAM BUFKIT MOMENTUM TRANSFER INDICATED GUSTS OF 25
TO 30 KNOTS. THE HRRR INDICATED GUSTS OF 30 TO 35 KNOTS OVER MUCH
OF THE AREA THIS AFTERNOON. OBSERVATION TRENDS SUPPORT THESE WIND
GUSTS. A LAKE WIND ADVISORY REMAINS IN EFFECT. AN AREA OF
CONVERGENCE WAS SUPPORTING A BROKEN LINE OF SHOWERS IN THE
FORECAST AREA. THIS LINE SHOULD MOVE OUT OF THE AREA LATER THIS
AFTERNOON AND EXPECT COVERAGE WILL REMAIN LIMITED BY ISENTROPIC
DOWNGLIDE.
TONIGHT...THE LOW WILL BE SHIFTING FARTHER NORTHEAST OF THE AREA
WITH A DIMINISHING PRESSURE GRADIENT AND WIND. MODEL TIME
SECTIONS SHOW FURTHER LOW-LEVEL DRYING. HIGH CLOUDINESS
ASSOCIATED WITH AN UPPER-LEVEL SPEED MAXIMUM WILL SHIFT EASTWARD
TONIGHT. WE USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE
FORECAST.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
THE NAM AND GFS SHOW WEAK RIDGING DOMINATING THURSDAY INTO FRIDAY. A
REINFORCING DRY COLD FRONT APPEARS TO CROSS THE AREA FRIDAY
AFTERNOON AND EVENING. THE GUIDANCE TEMPERATURES WERE CLOSE.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE GFS AND ECMWF SHOW DEEP AND PROGRESSIVE TROUGHING SATURDAY AND
SUNDAY. THERE HAVE BEEN MODEL DIFFERENCES WITH THE AMOUNT OF
MOISTURE ASSOCIATED WITH A SHORTWAVE TROUGH LATE SATURDAY...BUT
GENERALLY THE MESSAGE HAS BEEN LIMITED MOISTURE AND DOWNSLOPE
FLOW. THE MOS POPS FROM THE GFS AND ECMWF FOR THIS PERIOD OVER THE
PAST FEW DAYS HAVE BEEN LOW. WE HAVE MAINTAINED THE DRY FORECAST.
THE MODELS AGREE SHOWING HIGH MOISTURE TUESDAY ASSOCIATED WITH A
COLD FRONT. THE GFS AND ECMWF MOS SUPPORT BELOW NORMAL
TEMPERATURES SATURDAY THROUGH MONDAY...AND NEAR NORMAL DURING THE
REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
A WEAK LOW PRESSURE SYSTEM WILL SLOWLY LIFT NORTH OF THE AREA THIS
AFTERNOON. A COLD FRONT WILL MOVE THROUGH BY EARLY THIS EVENING.
AS THE WARM FRONT LIFTS NORTH OF THE AREA CONDITIONS WILL IMPROVE
AND AS LOW CLOUDS BEGIN TO LIFT DURING THE 19Z-21Z TIME PERIOD. A
FEW SPRINKLES MAY STILL BE POSSIBLE AT THIS TIME. DEEP MIXING WITHIN
AN INCREASING PRESSURE GRADIENT/COLD FRONTAL PASSAGE FROM THE
WEST...WILL RESULT IN STRONG SOUTHWEST TO WESTERLY WINDS WITH GUSTS
TO 25 KNOTS. WINDS WILL SUBSIDE BY EARLY THIS EVENING...WITH SKIES
BECOMING CLEAR DURING THE OVERNIGHT HOURS. HIGH PRESSURE WILL BUILD
OVER THE AREA THURSDAY.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION
EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR SCZ015-016-
018-020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR GAZ040-
063>065-077.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1235 PM EST WED FEB 13 2013
.SYNOPSIS...
LOW PRESSURE WILL BE LIFTING NORTHEAST OF THE FORECAST AREA THIS
AFTERNOON AND TONIGHT. WEAK HIGH PRESSURE WILL DOMINATE THURSDAY AND
FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE CENTERED NEAR THE FORECAST AREA WAS SUPPORTING AREAS
OF LIGHT RAIN AND DRIZZLE. LATER TODAY...THE LOW WILL BE FARTHER
NORTH OF THE AREA AND ISENTROPIC DOWNGLIDE WILL BECOME DOMINATE.
THE RAIN CHANCE SHOULD DECREASE. THE NAM AND GFS INDICATED H85
WINDS OF 40 TO 50 KNOTS AND THE KCAE 88D HAS VERIFIED THESE WINDS.
THE MODELS SHOWED THIS WIND CONTINUING FOR MUCH OF THE DAY...THEN
DIMINISHING LATE TODAY AND TONIGHT. LINGERING CLOUDINESS SHOULD
LIMIT MIXING...BUT WITH THE DRYING IN THE AFTERNOON IT SHOULD
BECOME BREEZY. THE NAM MOMENTUM TRANSFER INDICATED A POTENTIAL FOR
GUSTS NEAR 30 KNOTS. THE HRRR INDICATED WIND GUSTS OF 25 TO 30
KNOTS DEVELOPING IN THE SOUTH PART AROUND 100 PM...WITH GUSTS OF
30 TO 35 KNOTS OVER MUCH OF THE REMAINING AREA BEGINNING AROUND
300 PM. WE HAVE POSTED A LAKE WIND ADVISORY. MODEL TIME SECTIONS
SHOW FURTHER DRYING OVERNIGHT AND EXPECT SKIES WILL BECOME CLEAR.
WE USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
THE NAM AND GFS SHOW WEAK RIDGING DOMINATING THURSDAY INTO FRIDAY. A
REINFORCING DRY COLD FRONT APPEARS TO CROSS THE AREA FRIDAY
AFTERNOON AND EVENING. GUIDANCE AND LOCAL NUMBERS ARE VERY CLOSE
THROUGH THE PERIOD.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ALL OF THE MODELS SHOW A DEEP...PROGRESSIVE...TROUGH ACROSS THE
EASTERN HALF OF THE COUNTRY SATURDAY. THE ECMWF AND GFS DIFFER ON
THE SPEED AND STRENGTH OF ADDITIONAL UPPER-LEVEL ENERGY MOVING
THROUGH THE TROUGH AND EVENTUALLY HELPING TO LIFT THE TROUGH TO
THE EAST AND NORTHEAST BY SUNDAY OR MONDAY. THE GFS DEVELOPS LOW
PRESSURE OFF THE MID ATLANTIC COAST SATURDAY AND IS FASTER. THE
SLOWER ECMWF...DEVELOPS LOW PRESSURE OFF THE CAROLINA COAST
SATURDAY NIGHT AND SUNDAY MORNING. AT THIS TIME...WILL KEEP THE
FORECAST DRY FOR THE WEEKEND. THIS WILL BE FOLLOWED BY ANOTHER
QUICK MOVING SYSTEM APPROACHING THE REGION TUESDAY. THE MODELS
AGREE SHOWING A MOISTURE INCREASE TUESDAY ASSOCIATED WITH A COLD
FRONT. THE GFS AND ECMWF MOS SUPPORT BELOW NORMAL TEMPERATURES
SATURDAY THROUGH MONDAY...AND NEAR NORMAL DURING THE REST OF THE
MEDIUM-RANGE PERIOD.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
A WEAK BUT COMPLEX LOW PRESSURE SYSTEM WILL SLOWLY LIFT NORTHWARD
ACROSS THE AREA EARLY THIS AFTERNOON. EXPECT IFR OR LIFR CEILINGS TO
LIFT EARLY THIS AFTERNOON WITH PATCHY LIGHT SHOWERS OR DRIZZLE AT
TIMES...MAINLY OVER THE SC MIDLANDS.
AS THE WARM FRONT LIFTS NORTH OF THE AREA CONDITIONS SHOULD
IMPROVE AND AS LOW CLOUDS LIFT AFTER 18Z-21Z. DEEP MIXING WITHIN AN
INCREASING PRESSURE GRADIENT/COLD FRONTAL PASSAGE FROM THE
WEST...WILL RESULT IN STRONG SOUTHWEST TO WESTERLY WINDS WITH GUSTS
TO 25 KNOTS. WINDS WILL SUBSIDE BY EARLY THIS EVENING...WITH SKIES
BECOMING CLEAR DURING THE OVERNIGHT HOURS. HIGH PRESSURE WILL BUILD
OVER THE AREA THURSDAY.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION
EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR SCZ015-016-
018-020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR GAZ040-
063>065-077.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1041 AM EST WED FEB 13 2013
.SYNOPSIS...
LOW PRESSURE WILL BE LIFTING NORTHEAST OF THE FORECAST AREA THIS
AFTERNOON AND TONIGHT. WEAK HIGH PRESSURE WILL DOMINATE THURSDAY AND
FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE CENTERED NEAR THE FORECAST AREA WAS SUPPORTING AREAS
OF LIGHT RAIN AND DRIZZLE. LATER TODAY...THE LOW WILL BE FARTHER
NORTH OF THE AREA AND ISENTROPIC DOWNGLIDE WILL BECOME DOMINATE.
THE RAIN CHANCE SHOULD DECREASE. THE NAM AND GFS INDICATED H85
WINDS OF 40 TO 50 KNOTS AND THE KCAE 88D HAS VERIFIED THESE WINDS.
THE MODELS SHOWED THIS WIND CONTINUING FOR MUCH OF THE DAY...THEN
DIMINISHING LATE TODAY AND TONIGHT. LINGERING CLOUDINESS SHOULD
LIMIT MIXING...BUT WITH THE DRYING IN THE AFTERNOON IT SHOULD
BECOME BREEZY. THE NAM MOMENTUM TRANSFER INDICATED A POTENTIAL FOR
GUSTS NEAR 30 KNOTS. THE HRRR INDICATED WIND GUSTS OF 25 TO 30
KNOTS DEVELOPING IN THE SOUTH PART AROUND 100 PM...WITH GUSTS OF
30 TO 35 KNOTS OVER MUCH OF THE REMAINING AREA BEGINNING AROUND
300 PM. WE HAVE POSTED A LAKE WIND ADVISORY. MODEL TIME SECTIONS
SHOW FURTHER DRYING OVERNIGHT AND EXPECT SKIES WILL BECOME CLEAR.
WE USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
THE NAM AND GFS SHOW WEAK RIDGING DOMINATING THURSDAY INTO FRIDAY. A
REINFORCING DRY COLD FRONT APPEARS TO CROSS THE AREA FRIDAY
AFTERNOON AND EVENING. GUIDANCE AND LOCAL NUMBERS ARE VERY CLOSE
THROUGH THE PERIOD.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ALL OF THE MODELS SHOW A DEEP...PROGRESSIVE...TROUGH ACROSS THE
EASTERN HALF OF THE COUNTRY SATURDAY. THE ECMWF AND GFS DIFFER ON
THE SPEED AND STRENGTH OF ADDITIONAL UPPER-LEVEL ENERGY MOVING
THROUGH THE TROUGH AND EVENTUALLY HELPING TO LIFT THE TROUGH TO
THE EAST AND NORTHEAST BY SUNDAY OR MONDAY. THE GFS DEVELOPS LOW
PRESSURE OFF THE MID ATLANTIC COAST SATURDAY AND IS FASTER. THE
SLOWER ECMWF...DEVELOPS LOW PRESSURE OFF THE CAROLINA COAST
SATURDAY NIGHT AND SUNDAY MORNING. AT THIS TIME...WILL KEEP THE
FORECAST DRY FOR THE WEEKEND. THIS WILL BE FOLLOWED BY ANOTHER
QUICK MOVING SYSTEM APPROACHING THE REGION TUESDAY. THE MODELS
AGREE SHOWING A MOISTURE INCREASE TUESDAY ASSOCIATED WITH A COLD
FRONT. THE GFS AND ECMWF MOS SUPPORT BELOW NORMAL TEMPERATURES
SATURDAY THROUGH MONDAY...AND NEAR NORMAL DURING THE REST OF THE
MEDIUM-RANGE PERIOD.
&&
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
A WARM FRONT WILL SLOWLY LIFT NORTHWARD INTO THE AREA FROM CENTRAL
GEORGIA THIS MORNING. EXPECT IFR OR LIFR CEILINGS THROUGH THE REST
OF THE MORNING WITH PATCHY LIGHT SHOWERS OR DRIZZLE AT TIMES.
AS THE WARM FRONT LIFTS NORTH OF THE AREA CONDITIONS SHOULD
IMPROVE AND AS LOW CLOUDS LIFT AFTER 17Z-20Z. DEEP MIXING WITHIN AN
INCREASING PRESSURE GRADIENT/COLD FRONTAL PASSAGE FROM THE
WEST...WILL RESULT IN STRONG SOUTHWEST TO WESTERLY WINDS WITH GUSTS
TO 25 KNOTS.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION
EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR SCZ015-016-
018-020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR GAZ040-
063>065-077.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
626 AM EST WED FEB 13 2013
.PREV DISCUSSION... /ISSUED 423 AM EST WED FEB 13 2013/
SHORT TERM /TODAY THROUGH THURSDAY/...
LOW PRESSURE IS CURRENTLY ACROSS NORTHERN AL AND THE ASSOCIATED COLD
FRONT STRETCHES INTO THE GULF OF MEXICO. A WARM FRONT IS ALSO
SITUATED ALONG THE GA/FL BORDER. REGIONAL RADAR SHOWS THE HEAVIEST
PRECIP IN THE VICINITY OF A WEAK LOW PRESSURE MOVING EAST ALONG THE
WARM FRONT.
THE COLD FRONT WILL MOVE THROUGH THE NW HALF OF THE CWA DURING THE
EARLY MORNING AND THE REMAINDER OF THE CWA BY THE EARLY AFTERNOON.
MODELS HAVE BEEN AGGRESSIVE WITH MOVING THE WARM FRONT
NORTHWARD...BUT THE COOLER HIGH PRESSURE WEDGE HAS HELD FIRM AND
ALLOWED LITTLE NORTHWARD PROGRESSION. WITH BOUNDARY LAYER WINDS 15
TO 20 KT OUT OF THE SOUTH...DO THINK THAT THERE WILL BE A LITTLE
NORTHWARD PROGRESSION OF THE WARM SECTOR THIS MORNING...THUS THE
BEST INSTABILITY WILL REMAIN ACROSS THE SOUTHERN ZONES. WITH STEEP
MID LEVEL LAPSE RATES AND BUFKIT SOUNDINGS SHOWING AN INVERTED V
STRUCTURE...LARGE HAIL AND DAMAGING WIND GUSTS WOULD BE THE PRIMARY
MODE OF SEVERE WEATHER. HOWEVER...DO THINK IF SEVERE THUNDERSTORMS
DEVELOP THEY WILL BE ISOLATED IN NATURE.
PRECIP CHANCES WILL DIMINISH FROM WEST TO EAST BEHIND THE COLD FRONT
LATER THIS AFTERNOON. OVERNIGHT AND THURSDAY ARE EXPECTED TO REMAIN
DRY AS HIGH PRESSURE BUILDS OVERHEAD.
TOOK BLEND FOR MAX/MIN TEMPS.
NLISTEMAA
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
GFS AND ECMWF ARE IN CLOSE AGREEMENT IN THE LONG TERM. THE EASTERN
TROUGH DEEPENS AS A STRONG SHORT WAVES MOVES OUT OF CANADA AND INTO THE
CENTRAL AND EASTERN U.S. THIS WILL DRIVE AN ARCTIC FRONT INTO THE
CWA FRIDAY AND FRIDAY NIGHT. WITH EACH MODEL RUN THE MOISTURE IS
SHOWING UP LESS AND LESS AND APPEARS THAT LITTLE IF ANY PRECIP WILL
FALL FROM THIS SHORT WAVE. THE ONLY AREAS THAT COULD SEE SOME LIGHT
RAIN WILL BE EXTREME NORTH GA DURING THE DAY FRIDAY. CONTINUED
UPSLOPE FLOW IN THE NORTHEAST MOUNTAINS COULD YIELD A FEW SNOW
SHOWERS DURING THE DAY SATURDAY. STRONG COLD ADVECTION SATURDAY
COUPLED WITH 30 TO 40 KT H8 WINDS WILL YIELD WINDY CONDITIONS ON
SATURDAY ACROSS THE CWA. STILL LOOKS LIKE GFS GUIDANCE IS TOO WARM
ON THIS WEEKEND TEMPS AND HAVE DROPPED THEM CONSIDERABLY.
THIS ARCTIC SURGE WILL BE SHORT LIVED AS THE FLOW BECOMES ZONAL BY
MONDAY MORNING. THE SURFACE HIGH WILL BE TO OUR EAST WITH ANOTHER
SYSTEM DEVELOPING OVER THE MIDDLE OF THE COUNTY. TEMPS WILL MODERATE
BEGINNING MONDAY AFTER A COLD START. BY MONDAY EVENING/TUESDAY
MOISTURE WILL RETURN TO THE CWA. MOST OF THE ENERGY APPEARS TO BE IN
THE OHIO VALLEY BUT ANOTHER COLD FRONT WILL MOVE ACROSS THE CWA
TUESDAY BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS.
17
&&
.AVIATION...
12Z UPDATE...
LIFR CIGS AT THE TERMINALS THIS MORNING SHOULD CONTINUE UNTIL A W/SW
WIND SHIFT OCCURS BETWEEN 15-17Z. GUSTS 20-25 KT WILL BE POSSIBLE. A
COLD FRONT WILL ALSO MOVE THROUGH DURING THE LATE MORNING AND EARLY
AFTERNOON. HRRR PRODUCES A BROKEN LINE OF SHOWERS ALONG THE
FRONT...AND HAVE TRIED TO TIME THAT. WILL NOT REDUCE VSBSY AS PRECIP
WILL REMAIN SCT IN NATURE. VFR CONDITIONS AFTER 00-002Z.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE ON CIGS AND VSBY. HIGH CONFIDENCE ALL OTHER ELEMENTS.
NLISTEMAA
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 57 34 58 37 / 40 10 0 5
ATLANTA 55 36 57 40 / 40 10 0 5
BLAIRSVILLE 49 31 53 32 / 40 10 0 10
CARTERSVILLE 53 34 57 34 / 40 10 0 5
COLUMBUS 59 38 60 40 / 40 10 0 5
GAINESVILLE 54 34 55 38 / 40 10 0 5
MACON 61 38 60 36 / 40 20 0 5
ROME 53 34 57 32 / 40 10 0 10
PEACHTREE CITY 57 33 57 36 / 40 10 0 5
VIDALIA 70 43 61 41 / 40 30 0 10
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
153 AM EST WED FEB 13 2013
.SYNOPSIS...
A WARM FRONT WILL LIFT NORTH THROUGH THE REGION THIS MORNING
AS LOW PRESSURE PASSES TO THE WEST. A COLD FRONT WILL SWEEP
THROUGH THE AREA LATE TODAY...WITH HIGH PRESSURE EXPECTED TO
BUILD ACROSS THE REGION THURSDAY INTO EARLY SATURDAY. ANOTHER COLD
FRONT WILL PUSH THROUGH THE AREA SATURDAY...FOLLOWED BY STRONGER
HIGH PRESSURE AND COOLER CONDITIONS INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
EARLY WEDNESDAY MORNING SURFACE ANALYSIS REMAINED COMPLEX AS THE
WARM FRONT HAD ADVANCED TO AROUND ALTAMAHA SOUND...AHEAD OF A
SURFACE LOW CENTERED BETWEEN AMG AND JES. THIS LOW AND ASSOCIATED
WIDESPREAD PRECIPITATION CONTINUED TO DELAY THE NORTHWARD
PROGRESS OF THE WARM FRONT ACROSS SOUTHERN GEORGIA. NORTH OF THE
WARM FRONT... WIDESPREAD RAINS OCCASIONALLY PUNCTUATED BY ELEVATED
THUNDERSTORMS CONTINUED WITHIN BREAD SWATH OF DEEP LAYER
ASCENT/MOISTURE FLOWING ACROSS THE REGION FROM S/SW TO E/NE.
MODELS DOING A REASONABLE JOB WITH RAIN DEPICTION BUT MAY STRUGGLE
OVERNIGHT WITH THE DETAIL OF THE WARM FRONTAL PROGRESSION GIVEN
THE PRESENCE OF THE SURFACE LOW OVER SE GA AND COMPLICATED SURFACE
LAYERED STABILITY PROFILES. TEMPS WERE IN THE MID 50S MOST AREAS
AS NEAR SATURATION EVIDENT ON SOUNDING PROFILES. OVERNIGHT...A
FAIRLY UNSTABLE MID LEVEL ENVIRONMENT WILL SPREAD OVER THE
FORECAST REGION BUT GIVEN THE CURRENT RADAR TRENDS AND A MORE
BELIEVABLE RUC FORECAST...THE POTENTIAL FOR SEVERE WEATHER
OVERNIGHT DOES NOT APPEAR TOO IMPRESSIVE DESPITE INCREASING SHEAR
PROFILES. EVEN ACROSS FAR SOUTHERN COUNTIES/CLOSER TO THE WARM
FRONT WHERE THUNDERSTORMS WILL REMAIN MOST COMMON...THE POTENTIAL
FOR ISOLATED SEVERE WEATHER WILL BE SOMEWHAT GREATER BUT STILL
LIMITED DUE TO IMPACTS OF ONGOING/WIDESPREAD PRECIP ON SURFACE
BASED INSTABILITY.
CATEGORICAL POPS REMAIN IN ORDER OVERNIGHT. FORECASTS CONTINUE TO
INDICATE ONLY SLOWLY WARMING TEMPS WHERE RAINS WERE STEADIER AND
HEAVIER. THE BEST CHANCE FOR TEMPS RISING THROUGH THE 60S LATE
SHOULD BE TO THE S OF I-16.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
WEDNESDAY...A STRONG SHORTWAVE TROUGH CURRENTLY OVER THE SOUTHERN
PLAINS WILL STEADILY SHIFT EAST EARLY WEDNESDAY...BECOMING MORE
STRETCHED/SHEARED AS IT MOVES INTO THE TENNESSEE/LOWER MISSISSIPPI
VALLEYS BY MIDDAY. THIS UPPER LEVEL ENERGY WILL SUPPORT THE
DEVELOPMENT OF A SURFACE LOW LIFTING FROM THE GULF COAST STATES INTO
THE UPSTATE CAROLINAS AS THE DAY PROGRESSES. NUMERICAL MODELS ARE IN
DECENT AGREEMENT THAT THE ASSOCIATED WARM FRONT WILL BE LOCATED
RIGHT ALONG THE NORTHERN BORDER OF THE FORECAST AREA...PERHAPS
AROUND THE SANTEE RIVER...BY DAYBREAK WEDNESDAY. AS A
RESULT...TEMPERATURES WILL RISE WELL ABOVE SEASONAL NORMALS INTO THE
UPPER 60S NORTH TO LOWER 70S SOUTH.
BOTH 12Z NAM AND 12Z GFS SOLUTIONS INDICATE LOW TO MODERATE
INSTABILITY INCREASING ACROSS MUCH OF THE FORECAST AREA THROUGH
THE MORNING AND AFTERNOON HOURS...WITH CAPE VALUES POSSIBLY
REACHING 1000 J/KG OVER THE CHARLESTON TRI COUNTY REGION BY 18Z.
THE SOUTHEAST STATES WILL BE IN THE VICINITY OF THE RIGHT REAR
OF A 100 KT 500 MB JET AND A 30 TO 40 KT LOW LEVEL JET. THE
COMBINATION OF MODERATELY FAVORABLE INSTABILITY AND DECENT SHEAR
SUGGESTS ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE...WITH
A FEW THUNDERSTORMS POTENTIALLY BECOMING STRONG AND ORGANIZED.
STORM PREDICTION CENTER HAS PLACED THE SOUTHERN HALF OF THE
FORECAST AREA...WHERE TEMPERATURES AND DEWPOINTS WILL BE
HIGHEST...WITHIN A SLIGHT RISK FOR SEVERE THUNDERSTORM
DEVELOPMENT. WILL ADD MENTION OF ISOLATED STORMS POSSIBLY
BECOMING SEVERE IN THE HAZARDOUS WEATHER OUTLOOK. IT SHOULD BE
NOTED THAT THICK CLOUD COVER AND MARGINAL LAPSE RATES COULD
NEGATIVELY IMPACT STORM ORGANIZATION...AND MUCH UNCERTAINTY IN
THUNDERSTORM STRENGTH AND COVERAGE REMAINS.
WEDNESDAY NIGHT...AS THE SURFACE LOW CONTINUES TO LIFT
NORTH/NORTHEAST TOWARD THE MID ATLANTIC COASTLINE...A TRAILING
COLD FRONT WILL PULL THROUGH THE FORECAST AREA BY THE EVENING
HOURS. SHOWER AND THUNDERSTORM CHANCES WILL THUS END FAIRLY
QUICKLY FROM WEST TO EAST BETWEEN 00Z AND 06Z WEDNESDAY
NIGHT...WITH DRIER DEEP LAYER AIR MOVING IN BEHIND THE DEPARTING
FRONT. COLD ADVECTION OVERNIGHT WILL ALLOW TEMPERATURES TO FALL
INTO THE UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST.
THURSDAY AND FRIDAY...WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE
REGION AND SET UP PREVAILING WEST/NORTHWEST SYNOPTIC FLOW. EXPECT
DRY CONDITIONS AND SLIGHTLY COOLER TEMPERATURES...WITH HIGHS
GENERALLY REACHING THE MID 60S THURSDAY AND THE MID TO UPPER 60S
FRIDAY. LOW TEMPERATURES THURSDAY NIGHT WILL REFLECT IMPROVED
RADIATIONAL COOLING CONDITIONS UNDER CLEAR SKIES AND LIGHTER
WINDS...RANGING FROM THE MID TO UPPER 30S INLAND TO THE LOWER 40S
NEAR THE COAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AN ARCTIC FRONT WILL PUSH THROUGH THE SOUTHEAST STATES LATE
SATURDAY AHEAD OF A SHARP UPPER TROUGH DIVING TOWARD THE AREA FROM
THE GREAT LAKES/CENTRAL PLAINS REGION. THERE IS SOME EVIDENCE IN
MEDIUM RANGE MODEL SOLUTIONS OF ISOLATED RAIN ASSOCIATED WITH THE
UPPER TROUGH PROGRESSION TO SUPPORT SLIGHT CHANCE POPS FOR THE
NORTHERN HALF OF THE AREA SATURDAY NIGHT. GUIDANCE IS STILL
SHOWING HIGHS IN THE UPPER 50S TO LOWER 60S AHEAD OF THE FRONT ON
SATURDAY...BUT SUSPECT TEMPERATURES WILL BE FALLING DURING THE
AFTERNOON DEPENDING ON THE EXACT TIMING OF THE FRONT. THERE IS
SOME CONCERN ABOUT THE POTENTIAL FOR SOME BRIEF WINTRY PRECIP
WITH THIS FRONT...AS MODELS DROP 850MB TEMPS TO -2 TO -4C BY 00Z
SUNDAY. HOWEVER...BOUNDARY LATER TEMPS COULD BE TOO WARM. PREFER
TO CONTINUE MONITORING MODEL TRENDS FOR THIS PERIOD.
THE DEEP ARCTIC UPPER TROUGH PUSHES OFFSHORE INTO THE ATLANTIC
SUNDAY...THEN ZONAL FLOW TO SLIGHT RIDGING BUILDS BACK INTO THE
UPPER LEVELS FOR MONDAY. BELOW CLIMO TEMPS EXPECTED FOR SUNDAY AND
MONDAY WITH HIGHS IN THE 50S...AS WELL AS THE POTENTIAL FOR
FREEZING OVERNIGHT/EARLY MORNING TEMPS...ESPECIALLY MONDAY
MORNING. EXPECT MODERATING TEMPS BY TUESDAY AS MODELS SHOW
ANOTHER STRONG UPPER TROUGH AND ASSOCIATED SURFACE FRONT MOVING
TOWARD THE REGION. DUE TO UNCERTAINTY IN THE TIMING OF THIS
FEATURE...HAVE GONE WITH SLIGHT CHANCE TO CHANCE POPS.
&&
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
THE 06Z TAF PACKAGE ENCOMPASSES A COMPLEX PERIOD. INITIALLY...
WIDESPREAD RAIN NORTH OF A WARM FRONT WILL BE HEAVY AT TIMES AND
WILL BE ACCOMPANIED BY FLIGHT CONDITIONS RANGING FROM MVFR TO
LIFR. ELEVATED THUNDERSTORMS COULD IMPACT KSAV AND KCHS AT ANY
TIME THROUGH THIS MORNING. HOWEVER...PRECISE TIMING WILL REMAIN
DIFFICULT AND HAVE OPTED TO ISSUE AMENDMENTS AS REQUIRED TO
ADDRESS NEAR TERM CONVECTIVE TRENDS.
MAINTAINED LOW LEVEL WIND SHEAR TO ACCOUNT FOR SW WINDS AROUND 40
KT JUST ABOVE THE SURFACE OVERNIGHT INTO WEDNESDAY MORNING.
NORTHWARD PROGRESS OF THE WARM FRONT WILL TURN WINDS TO THE S/SW
AND SHOULD EVENTUALLY USHER IMPROVING CEILINGS/VISIBILITY LATER
THIS MORNING...AND PREVAILING VFR CONDITIONS SHOULD DEVELOP BY
LATE MORNING/EARLY AFTERNOON. HOWEVER...ADDITIONAL
SHOWERS/THUNDERSTORMS WILL DEVELOP AHEAD OF AN ADVANCING COLD
FRONT...AND THIS PRECIPITATION COULD IMPACT TERMINALS WITH BRIEF
FLIGHT RESTRICTIONS UNTIL LATE AFTERNOON. THUNDERSTORMS COULD
ACCOMPANY COLD FROPA AT BOTH TERMINALS...BUT A SLIGHTLY BETTER
CHANCE FOR THUNDERSTORMS SHOULD FOCUS AROUND KSAV.
THIS EVENING...POST COLD FROPA CONDITIONS SHOULD RETURN TO VFR
WITH NO ADDITIONAL FLIGHT RESTRICTIONS EXPECTED.
EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE WEEKEND.
&&
.MARINE...
A WARM FRONT AND ASSOCIATED LOW LEVEL JETTING/INCREASING SOUTHERLY
FLOW HAD ADVANCED INTO GA WATERS AND WILL CONTINUE TO ADVANCE
NORTH THROUGH SC WATERS OVERNIGHT. SOME GUSTS TO 25 KT WILL
OCCUR ACROSS THE OFFSHORE GA WATERS. ELSEWHERE IT WILL BE CLOSER
TO DAYBREAK WEDNESDAY WHEN THE WINDS BECOME MORE GUSTY. WE HAVE
THE SMALL CRAFT ADVISORY FOR OFFSHORE GA WATERS TONIGHT.
WEDNESDAY THROUGH SUNDAY...SMALL CRAFT ADVISORY CONDITIONS WILL
BE ONGOING FOR MUCH OF THE MARINE AREA WEDNESDAY...AS A SURFACE
LOW PASSES WELL NORTHWEST OF THE WATERS AND A COLD FRONT CROSSES
OFFSHORE DURING THE EVENING HOURS. EXPECT WINDS AND SEAS TO
GRADUALLY FALL BELOW ADVISORY LEVELS LATE WEDNESDAY NIGHT INTO
THURSDAY MORNING...WITH HIGH PRESSURE BUILDING OVER THE REGION
FROM THE WEST. A STRONGER COLD FRONT AND HIGH PRESSURE IS EXPECTED
TO SUPPORT ANOTHER SURGE IN WINDS TO ADVISORY LEVELS LATER
SATURDAY AND SATURDAY NIGHT. THERE IS EVEN THE POTENTIAL FOR SOME
MARGINAL GALE CONDITIONS SATURDAY NIGHT...HOWEVER UNCERTAINTY IS TOO
HIGH TO MENTION AT THIS POINT. WINDS AND SEAS WILL BE GRADUALLY
FALLING BACK BELOW HIGHLIGHTS SUNDAY...AS HIGH PRESSURE BUILDS
OVER THE REGION AGAIN.
&&
.HYDROLOGY...
LOCALLY HEAVY RAIN WILL CONTINUE OVERNIGHT...AND PERIODS OF
DROUGHT-RELIEVING RAINS TO CONTINUE THROUGH WEDNESDAY. STORM TOTAL
RAINFALL AMOUNTS OF 2-4 INCHES WILL BE SPREAD OVER A LONG ENOUGH
PERIOD TO PRECLUDE WIDESPREAD FLASH FLOOD ISSUES... BUT SEVERAL OF
OUR RIVERS ARE EXPECTED TO APPROACH FLOOD STAGE LATER IN THE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR AMZ352.
SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ374.
SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 5 AM EST
THURSDAY FOR AMZ350.
&&
$$
SYNOPSIS...
NEAR TERM...SPR
SHORT TERM...79
LONG TERM...RFM
AVIATION...SPR
MARINE...SPR
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1258 AM EST WED FEB 13 2013
.SYNOPSIS...
A STATIONARY FRONT OVER FAR SOUTH GEORGIA WILL LIFT NORTH INTO THE
AREA AS A WARM FRONT LATE TONIGHT...WHILE GULF LOW PRESSURE PASSES
TO THE WEST. A COLD FRONT WILL SWEEP THROUGH THE AREA LATE WEDNESDAY...
WITH HIGH PRESSURE EXPECTED TO BUILD ACROSS THE REGION THURSDAY INTO
EARLY SATURDAY. ANOTHER COLD FRONT WILL PUSH THROUGH THE AREA
SATURDAY...FOLLOWED BY STRONGER HIGH PRESSURE AND COOLER CONDITIONS
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
EARLY MORNING SURFACE ANALYSIS REMAINED COMPLEX AS THE WARM FRONT
HAS ADVANCED TO AROUND ALTAMAHA SOUND...AHEAD OF A SURFACE LOW
CENTERED NEAR AMG. THIS LOW AND ASSOCIATED WIDESPREAD
PRECIPITATION HAD THUS FAR DELAYED THE NORTHWARD PROGRESS OF THE
WARM FRONT ACROSS SOUTHERN GEORGIA. NORTH OF THE WARM FRONT...
WIDESPREAD RAINS OCCASIONALLY PUNCTUATED BY ELEVATED THUNDERSTORMS
CONTINUED WITHIN BREAD SWATH OF DEEP LAYER ASCENT/MOISTURE FLOWING
ACROSS THE REGION FROM S/SW TO E/NE.
MODELS DOING A REASONABLE JOB WITH RAIN DEPICTION BUT MAY STRUGGLE
OVERNIGHT WITH THE DETAIL OF THE WARM FRONTAL PROGRESSION GIVEN
THE PRESENCE OF THE SURFACE LOW OVER SE GA AND COMPLICATED SURFACE
LAYERED STABILITY PROFILES. TEMPS WERE IN THE MID 50S MOST AREAS
AS NEAR SATURATION EVIDENT ON SOUNDING PROFILES. OVERNIGHT...A
FAIRLY UNSTABLE MID LEVEL ENVIRONMENT WILL SPREAD OVER THE
FORECAST REGION BUT GIVEN THE CURRENT RADAR TRENDS AND A MORE
BELIEVABLE RUC FORECAST...THE POTENTIAL FOR SEVERE WEATHER
OVERNIGHT DOES NOT APPEAR TOO IMPRESSIVE DESPITE INCREASING SHEAR
PROFILES. EVEN ACROSS FAR SOUTHERN COUNTIES/CLOSER TO THE WARM
FRONT WHERE THUNDERSTORMS WILL REMAIN MOST COMMON...THE POTENTIAL
FOR ISOLATED SEVERE WEATHER WILL BE SOMEWHAT GREATER BUT STILL
LIMITED DUE TO IMPACTS OF ONGOING/WIDESPREAD PRECIP ON SURFACE
BASED INSTABILITY.
CATEGORICAL POPS REMAIN IN ORDER OVERNIGHT. FORECASTS CONTINUE TO
INDICATE ONLY SLOWLY WARMING TEMPS WHERE RAINS WERE STEADIER AND
HEAVIER. THE BEST CHANCE FOR TEMPS RISING THROUGH THE 60S LATE
SHOULD BE TO THE S OF I-16.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
WEDNESDAY...A STRONG SHORTWAVE TROUGH CURRENTLY OVER THE SOUTHERN
PLAINS WILL STEADILY SHIFT EAST EARLY WEDNESDAY...BECOMING MORE
STRETCHED/SHEARED AS IT MOVES INTO THE TENNESSEE/LOWER MISSISSIPPI
VALLEYS BY MIDDAY. THIS UPPER LEVEL ENERGY WILL SUPPORT THE
DEVELOPMENT OF A SURFACE LOW LIFTING FROM THE GULF COAST STATES INTO
THE UPSTATE CAROLINAS AS THE DAY PROGRESSES. NUMERICAL MODELS ARE IN
DECENT AGREEMENT THAT THE ASSOCIATED WARM FRONT WILL BE LOCATED
RIGHT ALONG THE NORTHERN BORDER OF THE FORECAST AREA...PERHAPS
AROUND THE SANTEE RIVER...BY DAYBREAK WEDNESDAY. AS A
RESULT...TEMPERATURES WILL RISE WELL ABOVE SEASONAL NORMALS INTO THE
UPPER 60S NORTH TO LOWER 70S SOUTH.
BOTH 12Z NAM AND 12Z GFS SOLUTIONS INDICATE LOW TO MODERATE
INSTABILITY INCREASING ACROSS MUCH OF THE FORECAST AREA THROUGH
THE MORNING AND AFTERNOON HOURS...WITH CAPE VALUES POSSIBLY
REACHING 1000 J/KG OVER THE CHARLESTON TRI COUNTY REGION BY 18Z.
THE SOUTHEAST STATES WILL BE IN THE VICINITY OF THE RIGHT REAR
OF A 100 KT 500 MB JET AND A 30 TO 40 KT LOW LEVEL JET. THE
COMBINATION OF MODERATELY FAVORABLE INSTABILITY AND DECENT SHEAR
SUGGESTS ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE...WITH
A FEW THUNDERSTORMS POTENTIALLY BECOMING STRONG AND ORGANIZED.
STORM PREDICTION CENTER HAS PLACED THE SOUTHERN HALF OF THE
FORECAST AREA...WHERE TEMPERATURES AND DEWPOINTS WILL BE
HIGHEST...WITHIN A SLIGHT RISK FOR SEVERE THUNDERSTORM
DEVELOPMENT. WILL ADD MENTION OF ISOLATED STORMS POSSIBLY
BECOMING SEVERE IN THE HAZARDOUS WEATHER OUTLOOK. IT SHOULD BE
NOTED THAT THICK CLOUD COVER AND MARGINAL LAPSE RATES COULD
NEGATIVELY IMPACT STORM ORGANIZATION...AND MUCH UNCERTAINTY IN
THUNDERSTORM STRENGTH AND COVERAGE REMAINS.
WEDNESDAY NIGHT...AS THE SURFACE LOW CONTINUES TO LIFT
NORTH/NORTHEAST TOWARD THE MID ATLANTIC COASTLINE...A TRAILING
COLD FRONT WILL PULL THROUGH THE FORECAST AREA BY THE EVENING
HOURS. SHOWER AND THUNDERSTORM CHANCES WILL THUS END FAIRLY
QUICKLY FROM WEST TO EAST BETWEEN 00Z AND 06Z WEDNESDAY
NIGHT...WITH DRIER DEEP LAYER AIR MOVING IN BEHIND THE DEPARTING
FRONT. COLD ADVECTION OVERNIGHT WILL ALLOW TEMPERATURES TO FALL
INTO THE UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST.
THURSDAY AND FRIDAY...WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE
REGION AND SET UP PREVAILING WEST/NORTHWEST SYNOPTIC FLOW. EXPECT
DRY CONDITIONS AND SLIGHTLY COOLER TEMPERATURES...WITH HIGHS
GENERALLY REACHING THE MID 60S THURSDAY AND THE MID TO UPPER 60S
FRIDAY. LOW TEMPERATURES THURSDAY NIGHT WILL REFLECT IMPROVED
RADIATIONAL COOLING CONDITIONS UNDER CLEAR SKIES AND LIGHTER
WINDS...RANGING FROM THE MID TO UPPER 30S INLAND TO THE LOWER 40S
NEAR THE COAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AN ARCTIC FRONT WILL PUSH THROUGH THE SOUTHEAST STATES LATE
SATURDAY AHEAD OF A SHARP UPPER TROUGH DIVING TOWARD THE AREA FROM
THE GREAT LAKES/CENTRAL PLAINS REGION. THERE IS SOME EVIDENCE IN
MEDIUM RANGE MODEL SOLUTIONS OF ISOLATED RAIN ASSOCIATED WITH THE
UPPER TROUGH PROGRESSION TO SUPPORT SLIGHT CHANCE POPS FOR THE
NORTHERN HALF OF THE AREA SATURDAY NIGHT. GUIDANCE IS STILL
SHOWING HIGHS IN THE UPPER 50S TO LOWER 60S AHEAD OF THE FRONT ON
SATURDAY...BUT SUSPECT TEMPERATURES WILL BE FALLING DURING THE
AFTERNOON DEPENDING ON THE EXACT TIMING OF THE FRONT. THERE IS
SOME CONCERN ABOUT THE POTENTIAL FOR SOME BRIEF WINTRY PRECIP
WITH THIS FRONT...AS MODELS DROP 850MB TEMPS TO -2 TO -4C BY 00Z
SUNDAY. HOWEVER...BOUNDARY LATER TEMPS COULD BE TOO WARM. PREFER
TO CONTINUE MONITORING MODEL TRENDS FOR THIS PERIOD.
THE DEEP ARCTIC UPPER TROUGH PUSHES OFFSHORE INTO THE ATLANTIC
SUNDAY...THEN ZONAL FLOW TO SLIGHT RIDGING BUILDS BACK INTO THE
UPPER LEVELS FOR MONDAY. BELOW CLIMO TEMPS EXPECTED FOR SUNDAY AND
MONDAY WITH HIGHS IN THE 50S...AS WELL AS THE POTENTIAL FOR
FREEZING OVERNIGHT/EARLY MORNING TEMPS...ESPECIALLY MONDAY
MORNING. EXPECT MODERATING TEMPS BY TUESDAY AS MODELS SHOW
ANOTHER STRONG UPPER TROUGH AND ASSOCIATED SURFACE FRONT MOVING
TOWARD THE REGION. DUE TO UNCERTAINTY IN THE TIMING OF THIS
FEATURE...HAVE GONE WITH SLIGHT CHANCE TO CHANCE POPS.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
THE 06Z TAF PACKAGE ENCOMPASSES A COMPLEX PERIOD. INITIALLY...
WIDESPREAD RAIN NORTH OF A WARM FRONT WILL BE HEAVY AT TIMES AND
WILL BE ACCOMPANIED BY FLIGHT CONDITIONS RANGING FROM MVFR TO
LIFR. ELEVATED THUNDERSTORMS COULD IMPACT KSAV AND KCHS AT ANY
TIME THROUGH THIS MORNING. HOWEVER...PRECISE TIMING WILL REMAIN
DIFFICULT AND HAVE OPTED TO ISSUE AMENDMENTS AS REQUIRED TO
ADDRESS NEAR TERM CONVECTIVE TRENDS.
MAINTAINED LOW LEVEL WIND SHEAR TO ACCOUNT FOR SW WINDS AROUND 40
KT JUST ABOVE THE SURFACE OVERNIGHT INTO WEDNESDAY MORNING.
NORTHWARD PROGRESS OF THE WARM FRONT WILL TURN WINDS TO THE S/SW
AND SHOULD EVENTUALLY USHER IMPROVING CEILINGS/VISIBILITY LATER
THIS MORNING...AND PREVAILING VFR CONDITIONS SHOULD DEVELOP BY
LATE MORNING/EARLY AFTERNOON. HOWEVER...ADDITIONAL
SHOWERS/THUNDERSTORMS WILL DEVELOP AHEAD OF AN ADVANCING COLD
FRONT...AND THIS PRECIPITATION COULD IMPACT TERMINALS WITH BRIEF
FLIGHT RESTRICTIONS UNTIL LATE AFTERNOON. THUNDERSTORMS COULD
ACCOMPANY COLD FROPA AT BOTH TERMINALS...BUT A SLIGHTLY BETTER
CHANCE FOR THUNDERSTORMS SHOULD FOCUS AROUND KSAV.
THIS EVENING...POST COLD FROPA CONDITIONS SHOULD RETURN TO VFR
WITH NO ADDITIONAL FLIGHT RESTRICTIONS EXPECTED.
EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE WEEKEND.
&&
.MARINE...
A WARM FRONT AND ASSOCIATED LOW LEVEL JETTING/INCREASING SOUTHERLY
FLOW HAD ADVANCED INTO GA WATERS AND WILL CONTINUE TO ADVANCE
NORTH THROUGH SC WATERS OVERNIGHT. SOME GUSTS TO 25 KT WILL
OCCUR ACROSS THE OFFSHORE GA WATERS. ELSEWHERE IT WILL BE CLOSER
TO DAYBREAK WEDNESDAY WHEN THE WINDS BECOME MORE GUSTY. WE HAVE
THE SMALL CRAFT ADVISORY FOR OFFSHORE GA WATERS TONIGHT.
WEDNESDAY THROUGH SUNDAY...SMALL CRAFT ADVISORY CONDITIONS WILL
BE ONGOING FOR MUCH OF THE MARINE AREA WEDNESDAY...AS A SURFACE
LOW PASSES WELL NORTHWEST OF THE WATERS AND A COLD FRONT CROSSES
OFFSHORE DURING THE EVENING HOURS. EXPECT WINDS AND SEAS TO
GRADUALLY FALL BELOW ADVISORY LEVELS LATE WEDNESDAY NIGHT INTO
THURSDAY MORNING...WITH HIGH PRESSURE BUILDING OVER THE REGION
FROM THE WEST. A STRONGER COLD FRONT AND HIGH PRESSURE IS EXPECTED
TO SUPPORT ANOTHER SURGE IN WINDS TO ADVISORY LEVELS LATER
SATURDAY AND SATURDAY NIGHT. THERE IS EVEN THE POTENTIAL FOR SOME
MARGINAL GALE CONDITIONS SATURDAY NIGHT...HOWEVER UNCERTAINTY IS TOO
HIGH TO MENTION AT THIS POINT. WINDS AND SEAS WILL BE GRADUALLY
FALLING BACK BELOW HIGHLIGHTS SUNDAY...AS HIGH PRESSURE BUILDS
OVER THE REGION AGAIN.
&&
.HYDROLOGY...
LOCALLY HEAVY RAIN WILL CONTINUE OVERNIGHT...AND PERIODS OF
DROUGHT-RELIEVING RAINS TO CONTINUE THROUGH WEDNESDAY. STORM TOTAL
RAINFALL AMOUNTS OF 2-4 INCHES WILL BE SPREAD OVER A LONG ENOUGH
PERIOD TO PRECLUDE WIDESPREAD FLASH FLOOD ISSUES... BUT SEVERAL OF
OUR RIVERS ARE EXPECTED TO APPROACH FLOOD STAGE LATER IN THE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR AMZ352.
SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ374.
SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 5 AM EST
THURSDAY FOR AMZ350.
&&
$$
SYNOPSIS...
NEAR TERM...SPR
SHORT TERM...79
LONG TERM...RFM
AVIATION...SPR
MARINE...SPR
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
117 AM EST WED FEB 13 2013
.AVIATION...
WARM AIR ADVECTION WAS INCREASING OVER THE WESTERN GREAT LAKES
REGION. A RECEDING SC CLOUD BANK WAS OVER LOWER MICHIGAN AND
EXTENDED INTO NRN INDIANA. HAVE MADE SOME MINOR ADJUSTMENTS IN THE
SCATTERING OUT OF THIS CLOUD LAYER. OTHERWISE...CONDITIONS WILL
BECOME VFR EARLY IN THE TAF PERIOD AND SHOULD PERSIST AS THE LOW
LEVEL FLOW REMAINS FROM THE WEST IN A RELATIVELY DRY AIRMASS.
&&
.PREV DISCUSSION... /ISSUED 307 PM EST TUE FEB 12 2013/
SHORT TERM... SFC RIDGING INVOF OF OH RVR WILL BREAK DOWN INADV
OF SW CLIPPER DROPPING OUT OF SWRN CANADA WED AFTN. HWVR NO
SENSIBLE WX OF CONSEQUENCE XPCD WITHIN THIS EVOLUTION THROUGH THIS
PD. MIXING/EROSION OF SC CLD DECK ONGOING THIS AFTN W/PARTIAL
SUNSHINE NOW ACRS MUCH OF ERN HALF CWA BUT WRN FLANK EXTENDING
BACK INTO NE IL HOLDING TOUGH AND MAY POSE A BUST OVERNIGHT WRT
MIN TEMPS. ATTM SHRT TERM RUC GIVES A NOD TWD PRIOR EVEN MOS
BLEND. OTRWS AT LEAST PARTIAL INSOLATION XPCD AGAIN ON WED W/STGR
DIURNAL WITHIN MODEST LL SWRLY FLW. IN FACT MOS MAX TEMP SPLIT
ESSENTIALLY EVEN AND REFLECTED IN GRIDDED MAXS.
LONG TERM... /THURSDAY THROUGH TUESDAY/
ACTIVE PATTERN IN STORE FOR THE LONG TERM PERIOD. ONE MORE DAY OF
ABOVE NORMAL TEMPS ON TAP FOR THURSDAY AHEAD OF SHOT OF ARCTIC AIR
DROPPING SE ACROSS THE PLAINS. STRONG FORCING ALONG THE FRONT WILL
STIR UP AT LEAST A CHC FOR RAIN OR SNOW SHOWERS BUT OVERALL QPF
APPEARS MINIMAL AT THIS POINT. POPS STILL HELD IN CHC/SCHC RANGE
FOR NOW. GREATER FOCUS THEN TURNS TOWARDS LAKE EFFECT POTENTIAL
AS STG NW FLOW SETS UP WITH SFC-850 MB DELTA T`S PUSHING 20 C AND
SFC-700 MB DELTA T`S PUSHING UPR 20S. NAM/WRF SHOW A PERIOD OF
FAVORABLE COLLOCATION OF DGZ AND TOP OF STRONG OMEGA. INVERSION
HGTS BEGIN TO CLIMB...ESPECIALLY DURING THE DAY FRIDAY WHEN SOME
ADDITIONAL SYNOPTIC MSTR ARRIVES AND A REINFORCING SHOT OF COLD
AIR. HAVE TENDED TO FOCUS GREATEST POPS FRIDAY TO MATCH WITH THE
ABOVE SETUP. ACCUMS AT THIS POINT APPEAR TO BE ON THE LIGHTER SIDE
BUT WILL NEED TO BE WATCHED IN COMING FORECASTS. WHILE AN
OUTLIER...SEVERAL RUNS OF THE GEM NHEM MODEL HAVE BEEN SHOWING
PHASING OF N/S STREAM SYSTEMS SOONER THAN LATER WITH A STORM
AFFECTING THE GREAT LAKES VS EAST COAST. ECMWF/GFS DO NOT PHASES
THE ENERGY UNTIL REACHING EAST COAST SO AT THIS POINT HAVE TO PUT
IT ON THE BACK BURNER BUT WILL NEED TO WATCH. LAKE EFFECT WILL
LINGER POTENTIALLY THROUGH MUCH OF THE WEEKEND WITH CONTINUED NW
FLOW AND 850 MB RIDGING STILL TO THE WEST UNTIL LATE SUNDAY. NEXT
SYSTEM TO FOCUS ON WILL BE WHAT LOOKS LIKE A PANHANDLE HOOK COMING
TOWARDS THE REGION MONDAY NIGHT INTO TUESDAY. SIGNALS POINT
TOWARDS MEASURABLE PRECIP FOR PARTS OF THE AREA BUT EXACT TRACK
AND AMOUNT OF COLD AIR REMAIN QUESTIONABLE THIS FAR OUT IN THE
FORECAST. HAVE WENT WITH MID-HIGH END CHC POPS WITH MIX OF RAIN OR
SNOW WITH LIKELY REFINEMENT OF FORECAST TO COME OVER THE NEXT
SEVERAL DAYS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...T
LONG TERM...FISHER
AVIATION...SKIPPER
AREA FORECAST DISCUSSION
NWS DES MOINES IA
543 PM CST THU FEB 14 2013
.SHORT TERM /TONIGHT/...
FORECAST CONCERN IS FOCUSED ON QUICK MOVING SHORTWAVE TO BRING SOME
LIGHT PRECIP TO THE FORECAST AREA THROUGH THIS EVENING. WEAK BROAD
FORCING ALONG THE COLD FRONT WILL BRING LIGHT SNOW OR RAIN THROUGH
THE LATE AFTERNOON BEFORE SWITCHING OVER TO ALL SNOW AFTER 00Z
FRIDAY. BUFR SOUNDINGS SHOWING BRIEF WINDOW OF FAIRLY DEEP
SATURATION FROM 21Z OR CURRENTLY THROUGH 03Z FRIDAY. COLUMN LOSES
ICE INTRODUCTION AND FORCING ACROSS NORTHERN IOWA B/T 00-03Z.
BELIEVE MODELS ARE BIT SLOW WITH MOVING THIS SYSTEM OUT AND CUT BACK
ON POPS PAST 03Z. 17Z HRRR QUICKLY DIMINISHES PRECIP BY 02Z WHICH
COINCIDES WITH SEVERAL OF THE HIRES WRF MODELS AND NAM12. ALSO
DECREASED SNOW AMOUNTS WITH THE QUICKER MOVEMENT...WEAKER FORCING
AND LESS MOISTURE AVAILABLE.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
COLD AIR SETTLING INTO THE REGION BY 12Z FRIDAY WITH GENERALLY A
CLOUDY DAY IN STORE. LINGERING FLURRIES WILL BE POSSIBLE FRIDAY WITH
WEAK WAVE PASSING THROUGH THE REGION DURING THE DAYTIME HOURS.
OTHERWISE TEMPERATURES WILL CREEP BACK UP DURING THE DAY TO NEAR 20
NORTH AND THE LOWER 30S IN THE SOUTH. AS HIGH BUILDS SOUTH FRIDAY
NIGHT SKIES WILL CLEAR OUT AND COLDER NIGHT IN STORE. LOWS WILL DROP
OFF INTO THE SINGLE DIGITS NORTH WITH THE TEENS IN THE SOUTHEAST.
H850 TEMPS REMAIN RATHER COLD THROUGH THE EARLY PART OF THE FORECAST
BUT AS THE RIDGE AXIS SLIPS EAST SATURDAY EVENING...TEMPS WARM
OVERNIGHT INTO SUNDAY MORNING. WARM AIR ADVECTION WILL INITIATE
CLOUDS WITH GENERALLY LIGHT FLOW OVERNIGHT. BY SUNDAY MED RANGE
MODELS CONTINUE WITH PREVIOUS RUNS TO SHOW DECENT WARM UP BY LATE
DAY. H850 TEMPS WARM TO NEAR 0C NORTHEAST AND TO NEAR 4-5C SOUTHWEST
AND WEST BY 00Z. THIS BODES WELL FOR TRENDS OF HIGHS IN THE 50S
ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA WITH HIGHS ABOVE
THE FREEZING MARK IN THE NORTHEAST. AS THE NEXT UPSTREAM WAVE
APPROACHES THE AREA ANOTHER STRONG COLD FRONT WILL PASS SOUTHEAST
THROUGH IOWA ON MONDAY. LIFT ASSOCIATED WITH IT WILL ALLOW FOR A
RAIN OR RAIN/SNOW MIXTURE TO OCCUR SOUTHEAST BY LATE IN THE
AFTERNOON. ANOTHER STRETCH OF COLDER THAN NORMAL WEATHER IS
ANTICIPATED FOR THE EARLY PORTION OF NEXT WEEK WITH A SLOW
MODERATION TOWARD THURSDAY...BUT STILL BELOW THE FREEZING MARK. MED
RANGE MODELS STILL PAINT AN ACTIVE STORM OVER THE FORECAST AREA BY
LATE WED OR EARLY THURSDAY WITH THE MAIN PORTION OF THE STORM TO HIT
THURSDAY THROUGH FRIDAY. SIGNATURE HAS SHOWN UP FOR TWO DAYS NOW IN
MOST MED RANGE MODELS...BUT EVEN SO...AT SEVEN DAYS OUT THERE ARE
STILL TO BE MANY CHANGES IN THE TRACK AND DETAILS. AT THIS TIME WILL
EMPHASIZE ONLY A STRONGER SYSTEM OVER THE CENTRAL STATES LOOKS MORE
LIKELY BUT WAY TOO EARLY TO BECOME OVERLY EXCITED ABOUT MODEL
DETAILS...ESPECIALLY GIVEN THAT THE 12Z GFS IS ABOUT 10 MB STRONGER
THAN THE 12Z EURO MODEL TODAY.
&&
.AVIATION...15/00Z
COLD FRONT EXTENDING FROM NERN IA INTO CENTRAL NEBRASKA WILL MOVE
SOUTH OF THE STATE THIS EVENING. LOCAL MVFR/IFR CONDITIONS IN CIG
AND -SNSN WILL MOVE SOUTH WITH THE FRONT. CLEARING WILL OVERSPREAD
THE TAF SITES TONIGHT. A PERIOD OF GUSTY NWLY WINDS IS EXPECTED
POST FROPA...BUT THEY WILL DIMINISH TOWARD 06Z. A WEAK SHORT WAVE
WILL DROP SOUTHEAST ACROSS THE STATE ON FRI BRINGING IN VFR CIGS AND
POCKETS OF MVFR CONDS IN CIG AND -SHSN.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...REV
AVIATION...MS FEB 13
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
537 PM CST THU FEB 14 2013
.AVIATION...
A FAST MOVING UPPER LEVEL DISTURBANCE IN CENTRAL IOWA WILL PRODUCE
AREAS OF LIGHT SNOW THROUGH 03Z BEFORE MOVING EAST. BRIEF PERIODS
OF MVFR CONDITIONS OF AS LOW AS 1-3K AGL AND VISIBILITIES OF 2-4
MILES IN SNOW ARE POSSIBLE WITH THE SNOW...MAINLY AT CID AND MLI
TERMINALS UNTIL 03Z. CLOUD CEILINGS WILL IMPROVE AND GRADUALLY BECOME
MOSTLY CLEAR BY DAYBREAK AS THE DISTURBANCE MOVES FURTHER EAST.
NORTHWEST WINDS OF 10 TO 20 KTS WILL GRADUALLY LOWER TO AROUND 10
TO 15 KTS ON FRIDAY.
NICHOLS
&&
.PREV DISCUSSION... /ISSUED 320 PM CST THU FEB 14 2013/
SYNOPSIS...
18Z SURFACE ANALYSIS INDICATED LOW PRESSURE OVER NORTHERN LOWER MI
WITH A TROUGH OR WEAK COLD FRONT REACHING SOUTH-SOUTHWEST ACROSS
IL...MO INTO EASTERN OK. A SECOND REINFORCING COLD FRONT EXTENDED
WEST FROM THE LOW ACROSS WI TO ALONG THE IA/MN BORDER. SOUTH OF THIS
FRONT...TEMPERATURES WERE IN THE 30S TO LOWER 40S WITH BRISK W-NW
WINDS ACROSS THE FORECAST AREA. ALOFT...A BROAD CYCLONIC FLOW
ENCOMPASSED THE EASTERN 2/3RDS OF THE CONTINENTAL U.S. THERE WERE A
SERIES OF SHORTWAVES EMBEDDED IN THIS FLOW FROM THE GREAT LAKES TO
THE CANADIAN ROCKIES. THE FOCUS IN THE SHORT TERM IS A VORT MAX
EVIDENT ON SATELLITE WV IMAGES OVER N CENTRAL IA...WHERE AREA RADARS
AND SURFACE REPORTS WERE INDICATING SNOW SHOWERS.
SHORT TERM...TONIGHT AND FRIDAY...
MAIN FOCUS IS ON THE SNOW SHOWERS THAT WILL OVERSPREAD THE AREA
LATE THIS AFTERNOON AND EVENING...THEN COOLER TEMPERATURES AND
POTENTIAL FLURRIES THROUGH FRIDAY.
AN AXIS OF ROTATION SEEN IN RECENT KDMX 88D LOOPS INDICATED THE
UPSTREAM VORT MAX WAS CENTERED ROUGHLY NORTH OF WEBSTER CITY AT 20Z.
THIS WAS WELL SOUTH OF THE OPERATIONAL NAM...GFS AND ECMWF TRACKS
FROM THIS MORNING. THE RECENT RAP RUNS APPEARED TO HAVE A DECENT
CAPTURE OF THIS VORT CENTER AND WILL FOLLOW ITS OVERALL
SOUTHEASTWARD TRACK. THIS WILL SEND THE UPSTREAM SNOW SHOWERS...
TRENDING HEAVIEST ALONG AND NORTH OF THE VORT MAX...SOUTHEAST
THROUGH THE EAST CENTRAL IA AND THEN W CENTRAL IL OVER THE NEXT
SEVERAL HOURS. COLD ADVECTION ALOFT WAS SHOWN LEADING TO STEEP MID
LEVEL LAPSE RATES ON THE ORDER OF 7 TO 8 DEG C/KM IN THIS MORNING/S
MODEL RUNS. THIS...COMBINED WITH THE UPPER LEVEL FORCING AND LIFT
ALONG THE SOUTHWARD MOVING COLD FRONT WILL SUPPORT CONTINUED LIGHT
TO MODERATE SNOW SHOWERS AND AT LEAST LIGHT ACCUMULATIONS. THE HIGH
RES RAP CONTINUES TO INDICATE QPF VALUES IN THE RANGE OF .2 TO .3
INCHES AS SNOW SHOWERS TRACK FROM ABOUT CID THROUGH THE QUAD CITIES
TO NEAR KEWANEE BETWEEN 23Z AND 05Z AND HAVE LIKELY POPS ALONG THIS
AXIS. WHILE THIS LOOKS OVERDONE BASED ON MEAGER PRECIPITATION
AMOUNTS REPORTED SO FAR AT AUTOMATED UPSTREAM SITES...CANNOT RULE
OUT BANDS OF 1 TO POSSIBLY 2 INCH SNOW ACCUMULATIONS IF THE
CONVECTION TAPS INTO THE DEEPER INSTABILITY OVER THE NEXT SEVERAL
HOURS. BASED ON THE INITIAL WARM LOW LEVELS AND TEMPERATURES IN
THE 30S TO LOWER 40S LEADING TO A RAIN/SNOW MIX AT ONSET...WILL
STAY CLOSE TO A MORE CONSERVATIVE .5 TO 1 INCH SNOWFALL RANGE FOR
NOW AND WATCH TRENDS CLOSELY.
THE CURRENT PACE OF THE VORT MAX SHOULD SEND THE SHOWERS EAST OF THE
AREA BY MID EVENING...AND HAVE ONLY SLIGHT CHANCE POPS AFTER
MIDNIGHT IN THE EAST AND SOUTHEAST. THE COLD FRONT SHOULD SLIDE
THROUGH THE ENTIRE AREA BY MIDNIGHT...FOLLOWED BY PARTIAL CLEARING
BASED ON SATELLITE TRENDS. GUIDANCE LOWS BY SUNRISE IN THE MID TEENS
NORTH TO MID 20S SOUTH LOOK REASONABLE.
FRIDAY...WILL KEEP A MENTION OF SCATTERED FLURRIES GOING IN THE
FORECAST BASED ON THE STREAM OF WEAK IMPULSES AND MID LEVEL MOISTURE
IN THE CYCLONIC FLOW ALOFT. CLOUD COVER AND COLD AIR ADVECTION
SHOULD LIMIT THE DIURNAL TEMPERATURE RISE. HAVE STAYED CLOSE TO
THE PREVIOUS FORECAST AND LATEST MODEL GUIDANCE WITH HIGHS
RANGING FROM THE LOWER 20S NORTH TO LOWER 30S SOUTH.
SHEETS
LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY
FRIDAY NIGHT AND SATURDAY WE REMAIN IN THE NORTHWEST CYCLONIC FLOW
AND STEEP MID LEVEL LAPSE RATES WITH ENOUGH LOW LEVEL MOISTURE TO
ALLOW FOR FLURRIES DURING THE OVERNIGHT AND SATURDAY MORNING. WE
ALSO HAVE SOME UPPER LEVEL VORT MAXES THAT SHOULD ALSO HELP TO
TRIGGER THESE FLURRIES. THERE IS NOT REALLY ENOUGH MOISTURE FOR MORE
THAN THAT...THOUGH A DUSTING IS POSSIBLE IF REPEAT ACTIVITY AFFECTS
THE SAME AREA. TEMPERATURES TO REMAIN COLD THROUGH SATURDAY WITH
HIGHS SATURDAY IN THE 20S TO AROUND 30. WARMED MINS FRIDAY NIGHT DUE
TO THE EXTRA CLOUD COVER AND RANGE FROM 10-20.
STRONG WARM AIR ADVECTION SETS IN OVER THE AREA AT 850MB SATURDAY
NIGHT AND SUNDAY. THIS IS LIKELY TO BRING ANOTHER BAND OF CLOUD
COVER ACROSS THE AREA OVERNIGHT AND SUNDAY MORNING. SATURDAY NIGHT
MINS ARE LIKELY TO NOT SHOW MUCH CHANGE YET AS MOST OF THE WARMING
IS ALOFT. SUNDAY HOWEVER WE ARE LIKELY TO SEE A BIG WARM-UP WITH
HIGHS IN THE MID 30S NORTHEAST TO THE UPPER 40S SOUTHWEST.
TEMPERATURES APPROACHING 50 ARE POSSIBLE IF WE CAN CLEAR OUT AND MIX
DEEPLY ENOUGH.
THE NEXT PUZZLE OF THE DAY IS MONDAY AND MONDAY NIGHT AS OUR NEXT
STRONG STORM SYSTEM CROSSES THE MIDWEST. A RELATIVELY SHALLOW
LONGWAVE TROUGH MOVES ACROSS THE AREA WITH TWO SEPARATE PIECES OF
ENERGY...ONE FARTHER NORTH THAT GENERATES A SURFACE LOW OVER
SOUTHERN MINNESOTA BY MONDAY MORNING. ANOTHER PIECE OF ENERGY IS
OVER NEW MEXICO WHICH GENERATES A SURFACE LOW OVER OKLAHOMA AT THE
SAME TIME. THIS SYSTEM SWEEPS OUT ACROSS THE MIDWEST MONDAY AND
MONDAY NIGHT. MODELS HAVE BEEN VARYING ON HOW WELL PHASED THESE
SYSTEMS WILL BE OVER THE PAST COUPLE DAYS AS WELL AS HOW MUCH ENERGY
WILL BE WITH EACH. THUS...THE IMPACT FOR OUR CWA HAS VARIED FROM
DRY TO A RAIN/SNOW MIX. FOR NOW MODELS ARE COMING IN A LITTLE
SLOWER AND STRONGER...AND ARE BRINGING MORE MOISTURE AND WARMTH INTO
THE AREA. THUS...HAVE RAISED POPS THROUGH THE PERIOD. ALSO...HAVE
CONVERTED MONDAY TO NEARLY ALL RAIN...WITH JUST A RAIN SNOW MIX
ACROSS THE NORTH. MONDAY NIGHT WE GRADUALLY SWITCH TO ALL
SNOW...BUT THE TIMING IS STILL VERY MUCH UP IN THE AIR. DUE TO THE
START BEING ALL RAIN...SNOWFALL AMOUNTS WILL BE LIGHT.
TUESDAY AND WEDNESDAY ARE RELATIVELY QUIET WITH A STRONG SURFACE
RIDGE BUILDING INTO THE AREA FOR DRY AND COLD CONDITIONS. IN
FACT...IF WE CAN GET DECENT RADIATIONAL CONDITIONS FOR TUESDAY NIGHT
MIN TEMPS COULD DIP INTO THE SINGLE DIGITS OVER A FAIRLY LARGE
PORTION OF THE AREA. HOWEVER...THIS IS STILL SOMEWHAT QUESTIONABLE
AND HAVE STAYED A LITTLE WARMER FOR NOW.
THE BIG QUESTION OF THE FORECAST COMES THURSDAY. FOR SEVERAL MODEL
RUNS NOW...THE ECMWF AND GFS HAVE BEEN ADVERTISING A VERY STRONG
STORM FOR THE MIDWEST ON THURSDAY AND FRIDAY. THERE IS REMARKABLE
CONSISTENCY AND CONFIDENCE IS GROWING THAT SOMEWHERE IN THE MIDWEST
THERE WILL BE A MAJOR WINTER STORM...IF NOT A BLIZZARD.
HOWEVER...WHETHER OUR AREA WILL BE AFFECTED OR NOT IS VERY MUCH IN
QUESTION. WE CURRENTLY HAVE DIFFERING MODEL SOLUTIONS...ONE OF WHICH
DEPICTS THE WINTER STORM AFFECTING THE CWA WITH MAJOR SNOW
ACCUMULATIONS...ANOTHER WHICH BRINGS IN MORE WARM AIR AND AFFECTS US
WITH ANOTHER RAIN/SNOW MIX EVENT WITH LESSER ACCUMULATIONS. IN
GENERAL PREFER THE MORE CONSISTENT AND BETTER VERIFYING ECMWF WHICH
HAS THE LARGER SNOW ACCUMULATIONS...BUT CANNOT TOTALLY DISCOUNT THE
WARMER GFS EITHER. WE WILL HAVE TO WATCH THIS STORM VERY CAREFULLY
OVER THE NEXT SEVERAL DAYS TO MONITOR THESE TRENDS. YOU WILL
DEFINITELY WANT TO KEEP UP WITH THE LATEST INFORMATION REGARDING
THIS WINTER STORM SYSTEM. FOR NOW THE LATEST FORECAST REFLECTS A
BLENDED APPROACH...AND WE WILL HAVE TO REFINE WITH LATER FORECASTS.
.LE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
NICHOLS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
150 PM EST WED FEB 13 2013
.Forecast Update...
Issued at 150 PM EST Wed Feb 13 2013
Snow continues to wind down across northwest sections of the
forecast area. Satellite data does show clouds breaking up to our
west so some peeks of sunshine will be possible. Temperatures have
already risen a few degrees since the snowfall ended and snow has
largely melted away already in the Metro area. With the threat of
snow greatly diminished, have gone ahead and cancelled the western
section of the winter weather advisory.
Further east, band of light to moderate snow continues to work
eastward and will be impacting the Lexington metro region. This
will put down a quick accumulation mainly on grassy surfaces before
diminishing to flurries later this afternoon.
&&
.Short Term (Now through Thursday)...
Issued at 325 AM EST Wed Feb 13 2013
...Light Slushy Snow Accumulations Possible Today...
As of 745Z, an upper trough was over MO with sfc low pressure over
the Gulf States. Precipitation associated with this system
stretched from western KY to eastern OK as of 745Z with rain
observed over most areas ESE of the upper trough and snow or a
rain/snow mix observed over portions of OK/MO/AR in the upper level
trough. The 6Z NAM12 and last few RAP runs seem to have the best
handle on the area of precipitation and general schematic of ptype.
Overall timing of the best precip and forcing seems to be a little
earlier than previously thought. Looks like the best dynamics and
precip should fall over our region between 12-18Z. Also, the latest
runs of the NAM and RAP have moved the best band of moderate to
heavy precip...probably a heavy wet snow as observed out in MO...to
the north. According to these models, the best snow band in which
we could see 1-2 inches of wet, slushy snow would be in a corridor
along the Ohio River to along the Western KY and Bluegrass
Parkways. Other areas over southern Indiana and south central KY
may see a brief mix of rain/snow...enough to create a dusting to a
half inch before quickly melting off. There is still some
uncertainty in where the band of moderate to heavy snow will set up
so stay tuned to morning forecast updates. Also, because of the
uncertainty, will continue with the SPS product instead of going
with an advisory although one may be needed later this morning.
So for today expect light rain to overspread the area before sunrise
with possibly some snow grains mixing in over southern Indiana and
northern KY at precip onset due to a deeper cold layer. After
sunrise we`ll start to see colder air filter in with the upper
trough causing precip to change over to a rain/snow mix and then
probably all snow for a time over southern Indiana and central KY.
The morning hours after sunrise through early afternoon will be the
best time for a period of moderate to heavy wet snow resulting in
slushy snow accumulations as high as 1-2 inches over north central
KY. This period of wintry precip may cause some travel issues.
We`ll continue to see a early afternoon before precip exits to our
east by late afternoon/early evening. Once snow comes to an end
over any location, quick melting can be expected as sfc temps are
expected to be above freezing today. In fact, most locations will
still top out in the upper 30s to lower 40s this afternoon despite
any morning/early afternoon snow.
For tonight and Thurs, expect dry conditions with partly cloudy
skies. Low temps will be in the upper 20s to lower 30s tonight. An
upper level trough and cold front will approach the region by Thurs
evening. Ahead of the trough, though, Thurs will be quite warm with
a strong southerly flow in place. High temps Thurs should be in the
low to mid 50s.
.Long Term (Thursday Night - Tuesday)...
Issued at 320 AM EST Wed Feb 13 2013
...A few shots for snow showers followed by a warm up and another
strong storm system early next week...
A lead shortwave will move across the Great Lakes on Thursday night,
with the associated surface system dragging a moisture starved cold
frontal boundary through the region. A secondary shortwave will
quickly move across the Ohio Valley on Friday as overall trough
envelopes the eastern CONUS. Friday looks to be the best setup for
some snow showers across the area as enough deep moisture combines
with steep low and mid level lapse rates, and an upslope surface
component. Soundings for this time period do show some convective
instability with saturation well into the -10 -20 C range across
northern portions of the CWA. Surface temperatures may squeak into
the mid and upper 30s on Friday, however thermal profile will be
easily cold enough for all snow showers below 40 degrees, some of
which could produce bursts of heavy snow and gusty winds.
At this point, best location for snow looks to be across southern
Indiana and north central Kentucky. As was mentioned in the previous
forecast, these snow showers have the potential to cause an impact
across the region with very light but quick accumulations. This setup
will have to be monitored.
We should see a lull in the activity on Friday night with subsidence
behind the quickly departing shortwave. Temperatures will be much
cooler with lows dropping into the mid 20s. By Saturday, confidence
is low as to exact placement of trough axis. Models are still having
trouble with the timing/placement of individual waves and the
overall progression of the east CONUS trough amplification. Have
continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble
mean consensus agree on an eastern solution with subsidence aloft
already in place across the Ohio Valley on Saturday. The less
consistent ECMWF still holds the axis to the west. Will only mention
a slight chance of a snow shower east of I-65 to account for this.
May be able to go completely dry for Saturday with the next set of
model runs. Temperatures will be cooler than Friday with highs only
topping out in the low and mid 30s.
Saturday night/Sunday morning will be the coldest of the period as
lows drop to around 20. Radiational cooling conditions will not be
optimal as surface winds stay up a bit and some upper level clouds
look to stream overhead. Therefore, cannot drop low too near dew
points that will be in the lower teens. May be able to decouple a
few of the coolest spots into the upper teens but the upper level
cloud cover should mostly mitigate this.
Saturday night through most of Monday should be dry as surface high
pressure holds over the area and weak upper level ridging holds.
Sunday will begin the warming trend with highs warming into the mid
30s to low 40s. Highs on Monday will be much milder with a return of
southerly flow. The mercury should rebound to the low 50s in most
spots.
By Monday afternoon we will begin to focus on the next storm system
that looks to impact the area through Tuesday. This system will
develop as a lee surface low intensifies ahead of a digging trough
over the central Plains. At this point the low looks to move from
the southern Plains, northeastward either into the Ohio Valley or
just north to the lower Great Lakes through Tuesday morning. This
warmer solution would bring overrunning rain showers to the area
late Monday afternoon, with more widespread rain moving into the
area Monday night and early Tuesday. Temperatures will likely crash
quickly behind the system on Tuesday afternoon as sharp trough moves
through and may eventually have to mention rain changing to snow.
Will stick with all rain for now as it is too early to mention these
details, especially with the low track in question. Will also leave
any thunder mention out of the forecast with the bulk of the
precipitation as any moisture return/instability would be limited by
short duration of southerly flow. This system will have to be
watched however, as a more northerly solution or deeper sfc low
would change the instability picture. Also, chose to disregard the
more southern solution offered by the operational ECMWF. This seems
to be the outlier, with a general consensus between the GFS/GEM/GFS
ensemble mean/ECMWF ensemble mean of a northern solution.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1235 PM EST Wed Feb 13 2013
Mid-level vorticity maximum continues to push eastward across the
forecast area this afternoon. Weakening band of heavy to moderate
snow will continue to push eastward. It should be east of KSDF by
the beginning of the TAF period, but several bands still remain to
the west which should push through over the next hour. MVFR
conditions look likely, but can not rule out a tempo drop to IFR as
these bands push through. VFR conditions are expected to return to
KSDF by 13/21Z and continue through the remainder of the TAF
period. Winds will be out of the northwest at 5-8 knots and then
gradually shift the west and then southwest later this afternoon and
tonight.
Over at KLEX, band of snow between KSDF and KLEX will push eastward
this afternoon and bring snow to the KLEX terminal. Current
thinking is the band will go through KLEX between 13/18-20Z or so
and conditions will likely drop to IFR for a short period of time
before rising back up to MVFR by 13/21Z. VFR conditions should
return to KLEX by 14/00Z. Surface winds will be out of northwest at
8-10 kts with winds shifting back to the west/southwest tonight.
Down at KBWG, some light rainfall mixed with a little snow will be
possible over the next few hours. In general, MVFR cigs and VFR
visibilities are expected, but VFR conditions should return by
13/21Z. VFR conditions are expected overnight with winds remaining
out of the southwest at 3-6 knots.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
KYZ035>037-039>043-046>049-054>057-067.
$$
Update...........MJ
Short Term.......AMS
Long Term........BJS
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
113 PM EST WED FEB 13 2013
.UPDATE...
ISSUED AT 931 AM EST WED FEB 13 2013
LIGHT...INTERMITTENT RAIN WITH TEMPS AROUND 40 COVERING MOST OF THE
CWFA. LOWER TEMPS AND LIGHT SNOW TO OUR WEST. UPDATED GRIDS TO
INDICATE LATE MORNING HIGH TEMPS AND THEN FALLING TEMPS THIS
AFTERNOON. RAIN SHOULD CHANGE TO SNOW AND THERE MAY BE A FEW BANDS OF
SNOW TO ACCUMULATE BUT THE GROUND AND ESPECIALLY THE ROADS ARE TOO
WARM TO SUPPORT OTHER THAN MOMENTARY ACCUMULATIONS. BY THE TIME THE
COLD AIR ARRIVES AND THE RAIN CHANGES TO ALL SNOW...MOST OF THE
MOISTURE WILL BE EAST OF THE AREA AND JUST A FEW FLURRIES WILL REMAIN
FOR ALL BUT THE HIGHER ELEVATIONS NEAR THE VA/W VA BORDER. UPDATED
GRIDS AND ZONES WITH LATEST INFORMATION.
UPDATE ISSUED AT 658 AM EST WED FEB 13 2013
CURRENT CONDITIONS ACROSS EASTERN KENTUCKY HAVE PRECIP MOVING INTO
THE AREA WITH RAIN REACHING THE GROUND IN THE SOUTH. HAVE UPDATED TO
FINE TUNE POPS AND ANY COOLING EFFECTS TO TEMPS FROM THE RAINFALL.
UPSTREAM...IT SEEMS THE BAND SETTING UP WILL STAY JUST NORTH SO WILL
KEEP CURRENT SNOWFALL FORECAST IN PLACE. ONLY CONCERN RIGHT NOW IS
THE COOLING EFFECTS AND SURFACE TEMPS OVER THE SOUTH AS SOME REPORTS
OF MODERATE RAIN POSSIBLY REALLY COOLING SURFACE TEMPS. WILL BANK ON
SURFACE TEMPS STAYING WARM ENOUGH THROUGH THE EARLY AFTERNOON BEFORE
THE COLD AIR FINALLY CHANGES THE RAIN OVER THIS AFTERNOON.
ALSO...MODEL SOUNDINGS CONTINUE TO SHOW DRY AIR AIR AT THE 10 DEGREE
CELSIUS TEMPS AND HIGHER SO WILL KEEP THE INCH OR SNOW FORECAST NORTH
OF THE MOUNTAIN PARKWAY AND IN THE HIGHEST ELEVATIONS SO NO NEW ZFP
WAS NEEDED.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 423 AM EST WED FEB 13 2013
CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER
EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH
CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES
ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER
30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY
ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP
INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY
SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND
SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN
IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A
BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION
OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF
HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND
GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT
WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING
MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE
GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO
RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE
SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND
INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A
RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE
HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS
STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE
EVENT...LOCATED FROM THE JKL POINT AND SOUTH.
BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH
POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN
ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A
BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA.
FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH
THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS
EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA
WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR
THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO
THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 341 AM EST WED FEB 13 2013
THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH
EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK
FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND
SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A
LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE
EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS
EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS
POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA.
THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF
ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF
HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS
THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING
ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL
BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS.
DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE
PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG
IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL
BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE
TEMPERATURE FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 108 PM EST WED FEB 13 2013
CEILINGS HAVE DROPPED TO IFR LEVELS. PRECIP HAS FALLEN THROUGH THE
MORNING ACROSS THE AREA IN THE FORM OF -RA. EXPECT THIS TO MIX WITH
AND THEN CHANGE TO -SN LATER THIS AFTERNOON. ACCUMULATIONS WILL BE
GENERALLY LIGHT EXCEPT IN NORTHERN KY WHERE A QUICK INCH COULD FALL.
PRECIP SHOULD END ACROSS EASTERN KENTUCKY BETWEEN 1-3Z WITH
CIGS/VSBY LIFTING TO VFR. WHERE THERE IS PRECIPITATION...THE -RA AND
THEN THE MIX OF TYPES COULD CAUSE SOME ICE ACCUMULATION WHEN AIRBORNE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR KYZ044-
050>052.
&&
$$
UPDATE...DUSTY
SHORT TERM...SHALLENBERGER
LONG TERM...JJ
AVIATION...DUSTY
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1203 PM EST WED FEB 13 2013
.Forecast Update...
Issued at 1202 PM EST Wed Feb 13 2013
Heavy snow band continues to steadily move eastward. The band is
now located just east and southeast of the Ohio River and currently
pushing through Louisville metro. This band has shown some
weakening in the last hour or so, but with the band passing over the
radar site, we might be seeing a little attenuation in the current
radar moments. This band will continue to head east through the
afternoon hours. Thus, have gone ahead and expanded the advisory to
the east to include all of the Bluegrass region of central
Kentucky. Overall, not expecting that many problems with
accumulation on the road surfaces as they have been pretty warm.
However, a short period of slushy roads will be
possible...especially on bridges and overpasses.
Further south, there is a little bit more warm air moving in which
is keeping the precipitation more in a mixed mode. It appears,
based on observations and reports that the pure snow line is along
the southern edge of the advisory area. Some colder air will move
in this afternoon which may result in a little more snow, but
accumulations will be very limited with a dusting or less.
There are some secondary bands that have formed to the west and
northwest across southern Indiana. In general, this snow is much
lighter than the main band, but light snow looks to continue through
the afternoon in southern Indiana with little additional
accumulation, and that would be limited to grassy surfaces.
&&
.Short Term (Now through Thursday)...
Issued at 325 AM EST Wed Feb 13 2013
...Light Slushy Snow Accumulations Possible Today...
As of 745Z, an upper trough was over MO with sfc low pressure over
the Gulf States. Precipitation associated with this system
stretched from western KY to eastern OK as of 745Z with rain
observed over most areas ESE of the upper trough and snow or a
rain/snow mix observed over portions of OK/MO/AR in the upper level
trough. The 6Z NAM12 and last few RAP runs seem to have the best
handle on the area of precipitation and general schematic of ptype.
Overall timing of the best precip and forcing seems to be a little
earlier than previously thought. Looks like the best dynamics and
precip should fall over our region between 12-18Z. Also, the latest
runs of the NAM and RAP have moved the best band of moderate to
heavy precip...probably a heavy wet snow as observed out in MO...to
the north. According to these models, the best snow band in which
we could see 1-2 inches of wet, slushy snow would be in a corridor
along the Ohio River to along the Western KY and Bluegrass
Parkways. Other areas over southern Indiana and south central KY
may see a brief mix of rain/snow...enough to create a dusting to a
half inch before quickly melting off. There is still some
uncertainty in where the band of moderate to heavy snow will set up
so stay tuned to morning forecast updates. Also, because of the
uncertainty, will continue with the SPS product instead of going
with an advisory although one may be needed later this morning.
So for today expect light rain to overspread the area before sunrise
with possibly some snow grains mixing in over southern Indiana and
northern KY at precip onset due to a deeper cold layer. After
sunrise we`ll start to see colder air filter in with the upper
trough causing precip to change over to a rain/snow mix and then
probably all snow for a time over southern Indiana and central KY.
The morning hours after sunrise through early afternoon will be the
best time for a period of moderate to heavy wet snow resulting in
slushy snow accumulations as high as 1-2 inches over north central
KY. This period of wintry precip may cause some travel issues.
We`ll continue to see a early afternoon before precip exits to our
east by late afternoon/early evening. Once snow comes to an end
over any location, quick melting can be expected as sfc temps are
expected to be above freezing today. In fact, most locations will
still top out in the upper 30s to lower 40s this afternoon despite
any morning/early afternoon snow.
For tonight and Thurs, expect dry conditions with partly cloudy
skies. Low temps will be in the upper 20s to lower 30s tonight. An
upper level trough and cold front will approach the region by Thurs
evening. Ahead of the trough, though, Thurs will be quite warm with
a strong southerly flow in place. High temps Thurs should be in the
low to mid 50s.
.Long Term (Thursday Night - Tuesday)...
Issued at 320 AM EST Wed Feb 13 2013
...A few shots for snow showers followed by a warm up and another
strong storm system early next week...
A lead shortwave will move across the Great Lakes on Thursday night,
with the associated surface system dragging a moisture starved cold
frontal boundary through the region. A secondary shortwave will
quickly move across the Ohio Valley on Friday as overall trough
envelopes the eastern CONUS. Friday looks to be the best setup for
some snow showers across the area as enough deep moisture combines
with steep low and mid level lapse rates, and an upslope surface
component. Soundings for this time period do show some convective
instability with saturation well into the -10 -20 C range across
northern portions of the CWA. Surface temperatures may squeak into
the mid and upper 30s on Friday, however thermal profile will be
easily cold enough for all snow showers below 40 degrees, some of
which could produce bursts of heavy snow and gusty winds.
At this point, best location for snow looks to be across southern
Indiana and north central Kentucky. As was mentioned in the previous
forecast, these snow showers have the potential to cause an impact
across the region with very light but quick accumulations. This setup
will have to be monitored.
We should see a lull in the activity on Friday night with subsidence
behind the quickly departing shortwave. Temperatures will be much
cooler with lows dropping into the mid 20s. By Saturday, confidence
is low as to exact placement of trough axis. Models are still having
trouble with the timing/placement of individual waves and the
overall progression of the east CONUS trough amplification. Have
continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble
mean consensus agree on an eastern solution with subsidence aloft
already in place across the Ohio Valley on Saturday. The less
consistent ECMWF still holds the axis to the west. Will only mention
a slight chance of a snow shower east of I-65 to account for this.
May be able to go completely dry for Saturday with the next set of
model runs. Temperatures will be cooler than Friday with highs only
topping out in the low and mid 30s.
Saturday night/Sunday morning will be the coldest of the period as
lows drop to around 20. Radiational cooling conditions will not be
optimal as surface winds stay up a bit and some upper level clouds
look to stream overhead. Therefore, cannot drop low too near dew
points that will be in the lower teens. May be able to decouple a
few of the coolest spots into the upper teens but the upper level
cloud cover should mostly mitigate this.
Saturday night through most of Monday should be dry as surface high
pressure holds over the area and weak upper level ridging holds.
Sunday will begin the warming trend with highs warming into the mid
30s to low 40s. Highs on Monday will be much milder with a return of
southerly flow. The mercury should rebound to the low 50s in most
spots.
By Monday afternoon we will begin to focus on the next storm system
that looks to impact the area through Tuesday. This system will
develop as a lee surface low intensifies ahead of a digging trough
over the central Plains. At this point the low looks to move from
the southern Plains, northeastward either into the Ohio Valley or
just north to the lower Great Lakes through Tuesday morning. This
warmer solution would bring overrunning rain showers to the area
late Monday afternoon, with more widespread rain moving into the
area Monday night and early Tuesday. Temperatures will likely crash
quickly behind the system on Tuesday afternoon as sharp trough moves
through and may eventually have to mention rain changing to snow.
Will stick with all rain for now as it is too early to mention these
details, especially with the low track in question. Will also leave
any thunder mention out of the forecast with the bulk of the
precipitation as any moisture return/instability would be limited by
short duration of southerly flow. This system will have to be
watched however, as a more northerly solution or deeper sfc low
would change the instability picture. Also, chose to disregard the
more southern solution offered by the operational ECMWF. This seems
to be the outlier, with a general consensus between the GFS/GEM/GFS
ensemble mean/ECMWF ensemble mean of a northern solution.
&&
.Aviation (12Z TAF Issuance)...
Issued at 605 AM EST Wed Feb 13 2013
An upper level trough will pass through the area today with a sfc
low pressure passing to our south. Precipitation associated with
this weather system has already begun to spread northward into
central KY this morning. At the beginning of TAF time, it should be
raining near all TAF sites with SDF/LEX rains being more
intermittent showers until deeper moisture overtakes the low level
dry layer. After sunrise, good forcing will enter the region
causing steady moderate banded precip over the region. It`s hard to
say whether a moderate band will affect the TAF sites, but at least
feel confident enough to include lower MVFR conditions this morning
through early afternoon as the heavier precip moves through the
region. Some IFR cigs may be possible in some of the heavier bands
of precip especially near BWG but will not include in the TAF at
this time as confidence is low. Rain is expected to be the
predominant precip type for BWG, however, SDF/LEX could see a RASN
mix in a moderate band. A RASN mix isn`t out of the realm of
possibilities for BWG either, but seems most likely at SDF/LEX at
this time. Will need to adjust as the precip bands set up this
morning and move closer to our area. By mid to late afternoon,
precip should move east of the TAF sites with conditions returning
to high end MVFR and then VFR by this evening.
Winds will be predominantly NNE as the weather system moves through
the area this morning through mid afternoon. Winds will strengthen
throughout the day likely exceeding 7kt at times. Winds will shift
to the WNW behind this system by this evening.
NAM model soundings indicate a layer of low level moisture for
tomorrow morning which could indicate a light fog or low cigs. Will
not place flight restrictions at the end of the TAFs for now, but it
will be something to investigate further.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON
FOR INZ076>079-083-084-089>092.
KY...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON
FOR KYZ023>034-038-045-053.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
KYZ035>037-039>043-046>049-054>057-067.
$$
Update...........MJ
Short Term.......AMS
Long Term........BJS
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1103 AM EST WED FEB 13 2013
.Mesoscale Forecast Update...
Issued at 1103 AM EST Wed Feb 13 2013
Strong frontogenetical heavy snow band is now moving into the
Louisville Metro area. Conditions across the metro will deteriorate
quickly over the next 15-20 minutes as the snow picks up.
Visibilities will drop to less than a mile and the snow will quickly
accumulate. Temperatures have continued to drop to near their
dewpoints in the snow band, so we expect temperatures to drop right
to freezing in the next half hour as the band pushes in. The heavy
snow will last about 60-90 minutes and a good 1-2" of accumulation
is likely.
Webcams to our north and northwest show the accumulating snows
well. Via social media, we`re seeing reports of 2-3" and we had a
co-op observer in Crawford County IN report 2 inches in the last
hour. This snow band will also affect areas to the southwest of
Louisville including areas from Harrison County Indiana southwest
through Meade/Breckinridge/Hardin/Ohio/Grayson counties over the
next 60-90 minutes.
&&
.Short Term (Now through Thursday)...
Issued at 325 AM EST Wed Feb 13 2013
...Light Slushy Snow Accumulations Possible Today...
As of 745Z, an upper trough was over MO with sfc low pressure over
the Gulf States. Precipitation associated with this system
stretched from western KY to eastern OK as of 745Z with rain
observed over most areas ESE of the upper trough and snow or a
rain/snow mix observed over portions of OK/MO/AR in the upper level
trough. The 6Z NAM12 and last few RAP runs seem to have the best
handle on the area of precipitation and general schematic of ptype.
Overall timing of the best precip and forcing seems to be a little
earlier than previously thought. Looks like the best dynamics and
precip should fall over our region between 12-18Z. Also, the latest
runs of the NAM and RAP have moved the best band of moderate to
heavy precip...probably a heavy wet snow as observed out in MO...to
the north. According to these models, the best snow band in which
we could see 1-2 inches of wet, slushy snow would be in a corridor
along the Ohio River to along the Western KY and Bluegrass
Parkways. Other areas over southern Indiana and south central KY
may see a brief mix of rain/snow...enough to create a dusting to a
half inch before quickly melting off. There is still some
uncertainty in where the band of moderate to heavy snow will set up
so stay tuned to morning forecast updates. Also, because of the
uncertainty, will continue with the SPS product instead of going
with an advisory although one may be needed later this morning.
So for today expect light rain to overspread the area before sunrise
with possibly some snow grains mixing in over southern Indiana and
northern KY at precip onset due to a deeper cold layer. After
sunrise we`ll start to see colder air filter in with the upper
trough causing precip to change over to a rain/snow mix and then
probably all snow for a time over southern Indiana and central KY.
The morning hours after sunrise through early afternoon will be the
best time for a period of moderate to heavy wet snow resulting in
slushy snow accumulations as high as 1-2 inches over north central
KY. This period of wintry precip may cause some travel issues.
We`ll continue to see a early afternoon before precip exits to our
east by late afternoon/early evening. Once snow comes to an end
over any location, quick melting can be expected as sfc temps are
expected to be above freezing today. In fact, most locations will
still top out in the upper 30s to lower 40s this afternoon despite
any morning/early afternoon snow.
For tonight and Thurs, expect dry conditions with partly cloudy
skies. Low temps will be in the upper 20s to lower 30s tonight. An
upper level trough and cold front will approach the region by Thurs
evening. Ahead of the trough, though, Thurs will be quite warm with
a strong southerly flow in place. High temps Thurs should be in the
low to mid 50s.
.Long Term (Thursday Night - Tuesday)...
Issued at 320 AM EST Wed Feb 13 2013
...A few shots for snow showers followed by a warm up and another
strong storm system early next week...
A lead shortwave will move across the Great Lakes on Thursday night,
with the associated surface system dragging a moisture starved cold
frontal boundary through the region. A secondary shortwave will
quickly move across the Ohio Valley on Friday as overall trough
envelopes the eastern CONUS. Friday looks to be the best setup for
some snow showers across the area as enough deep moisture combines
with steep low and mid level lapse rates, and an upslope surface
component. Soundings for this time period do show some convective
instability with saturation well into the -10 -20 C range across
northern portions of the CWA. Surface temperatures may squeak into
the mid and upper 30s on Friday, however thermal profile will be
easily cold enough for all snow showers below 40 degrees, some of
which could produce bursts of heavy snow and gusty winds.
At this point, best location for snow looks to be across southern
Indiana and north central Kentucky. As was mentioned in the previous
forecast, these snow showers have the potential to cause an impact
across the region with very light but quick accumulations. This setup
will have to be monitored.
We should see a lull in the activity on Friday night with subsidence
behind the quickly departing shortwave. Temperatures will be much
cooler with lows dropping into the mid 20s. By Saturday, confidence
is low as to exact placement of trough axis. Models are still having
trouble with the timing/placement of individual waves and the
overall progression of the east CONUS trough amplification. Have
continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble
mean consensus agree on an eastern solution with subsidence aloft
already in place across the Ohio Valley on Saturday. The less
consistent ECMWF still holds the axis to the west. Will only mention
a slight chance of a snow shower east of I-65 to account for this.
May be able to go completely dry for Saturday with the next set of
model runs. Temperatures will be cooler than Friday with highs only
topping out in the low and mid 30s.
Saturday night/Sunday morning will be the coldest of the period as
lows drop to around 20. Radiational cooling conditions will not be
optimal as surface winds stay up a bit and some upper level clouds
look to stream overhead. Therefore, cannot drop low too near dew
points that will be in the lower teens. May be able to decouple a
few of the coolest spots into the upper teens but the upper level
cloud cover should mostly mitigate this.
Saturday night through most of Monday should be dry as surface high
pressure holds over the area and weak upper level ridging holds.
Sunday will begin the warming trend with highs warming into the mid
30s to low 40s. Highs on Monday will be much milder with a return of
southerly flow. The mercury should rebound to the low 50s in most
spots.
By Monday afternoon we will begin to focus on the next storm system
that looks to impact the area through Tuesday. This system will
develop as a lee surface low intensifies ahead of a digging trough
over the central Plains. At this point the low looks to move from
the southern Plains, northeastward either into the Ohio Valley or
just north to the lower Great Lakes through Tuesday morning. This
warmer solution would bring overrunning rain showers to the area
late Monday afternoon, with more widespread rain moving into the
area Monday night and early Tuesday. Temperatures will likely crash
quickly behind the system on Tuesday afternoon as sharp trough moves
through and may eventually have to mention rain changing to snow.
Will stick with all rain for now as it is too early to mention these
details, especially with the low track in question. Will also leave
any thunder mention out of the forecast with the bulk of the
precipitation as any moisture return/instability would be limited by
short duration of southerly flow. This system will have to be
watched however, as a more northerly solution or deeper sfc low
would change the instability picture. Also, chose to disregard the
more southern solution offered by the operational ECMWF. This seems
to be the outlier, with a general consensus between the GFS/GEM/GFS
ensemble mean/ECMWF ensemble mean of a northern solution.
&&
.Aviation (12Z TAF Issuance)...
Issued at 605 AM EST Wed Feb 13 2013
An upper level trough will pass through the area today with a sfc
low pressure passing to our south. Precipitation associated with
this weather system has already begun to spread northward into
central KY this morning. At the beginning of TAF time, it should be
raining near all TAF sites with SDF/LEX rains being more
intermittent showers until deeper moisture overtakes the low level
dry layer. After sunrise, good forcing will enter the region
causing steady moderate banded precip over the region. It`s hard to
say whether a moderate band will affect the TAF sites, but at least
feel confident enough to include lower MVFR conditions this morning
through early afternoon as the heavier precip moves through the
region. Some IFR cigs may be possible in some of the heavier bands
of precip especially near BWG but will not include in the TAF at
this time as confidence is low. Rain is expected to be the
predominant precip type for BWG, however, SDF/LEX could see a RASN
mix in a moderate band. A RASN mix isn`t out of the realm of
possibilities for BWG either, but seems most likely at SDF/LEX at
this time. Will need to adjust as the precip bands set up this
morning and move closer to our area. By mid to late afternoon,
precip should move east of the TAF sites with conditions returning
to high end MVFR and then VFR by this evening.
Winds will be predominantly NNE as the weather system moves through
the area this morning through mid afternoon. Winds will strengthen
throughout the day likely exceeding 7kt at times. Winds will shift
to the WNW behind this system by this evening.
NAM model soundings indicate a layer of low level moisture for
tomorrow morning which could indicate a light fog or low cigs. Will
not place flight restrictions at the end of the TAFs for now, but it
will be something to investigate further.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON
FOR INZ076>079-083-084-089>092.
KY...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON
FOR KYZ023>034-038-045-053.
$$
Mesoscale........MJ
Short Term.......AMS
Long Term........BJS
Aviation.........AMS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
932 AM EST WED FEB 13 2013
.UPDATE...
ISSUED AT 931 AM EST WED FEB 13 2013
LIGHT...INTERMITTENT RAIN WITH TEMPS AROUND 40 COVERING MOST OF THE
CWFA. LOWER TEMPS AND LIGHT SNOW TO OUR WEST. UPDATED GRIDS TO
INDICATE LATE MORNING HIGH TEMPS AND THEN FALLING TEMPS THIS
AFTERNOON. RAIN SHOULD CHANGE TO SNOW AND THERE MAY BE A FEW BANDS OF
SNOW TO ACCUMULATE BUT THE GROUND AND ESPECIALLY THE ROADS ARE TOO
WARM TO SUPPORT OTHER THAN MOMENTARY ACCUMULATIONS. BY THE TIME THE
COLD AIR ARRIVES AND THE RAIN CHANGES TO ALL SNOW...MOST OF THE
MOISTURE WILL BE EAST OF THE AREA AND JUST A FEW FLURRIES WILL REMAIN
FOR ALL BUT THE HIGHER ELEVATIONS NEAR THE VA/W VA BORDER. UPDATED
GRIDS AND ZONES WITH LATEST INFORMATION.
UPDATE ISSUED AT 658 AM EST WED FEB 13 2013
CURRENT CONDITIONS ACROSS EASTERN KENTUCKY HAVE PRECIP MOVING INTO
THE AREA WITH RAIN REACHING THE GROUND IN THE SOUTH. HAVE UPDATED TO
FINE TUNE POPS AND ANY COOLING EFFECTS TO TEMPS FROM THE RAINFALL.
UPSTREAM...IT SEEMS THE BAND SETTING UP WILL STAY JUST NORTH SO WILL
KEEP CURRENT SNOWFALL FORECAST IN PLACE. ONLY CONCERN RIGHT NOW IS
THE COOLING EFFECTS AND SURFACE TEMPS OVER THE SOUTH AS SOME REPORTS
OF MODERATE RAIN POSSIBLY REALLY COOLING SURFACE TEMPS. WILL BANK ON
SURFACE TEMPS STAYING WARM ENOUGH THROUGH THE EARLY AFTERNOON BEFORE
THE COLD AIR FINALLY CHANGES THE RAIN OVER THIS AFTERNOON.
ALSO...MODEL SOUNDINGS CONTINUE TO SHOW DRY AIR AIR AT THE 10 DEGREE
CELSIUS TEMPS AND HIGHER SO WILL KEEP THE INCH OR SNOW FORECAST NORTH
OF THE MOUNTAIN PARKWAY AND IN THE HIGHEST ELEVATIONS SO NO NEW ZFP
WAS NEEDED.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 423 AM EST WED FEB 13 2013
CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER
EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH
CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES
ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER
30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY
ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP
INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY
SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND
SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN
IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A
BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION
OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF
HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND
GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT
WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING
MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE
GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO
RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE
SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND
INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A
RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE
HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS
STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE
EVENT...LOCATED FROM THE JKL POINT AND SOUTH.
BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH
POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN
ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A
BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA.
FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH
THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS
EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA
WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR
THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO
THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 341 AM EST WED FEB 13 2013
THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH
EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK
FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND
SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A
LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE
EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS
EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS
POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA.
THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF
ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF
HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS
THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING
ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL
BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS.
DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE
PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG
IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL
BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE
TEMPERATURE FORECAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 658 AM EST WED FEB 13 2013
WITH STILL A DRY LOWER LAYER TO OVERCOME...MVFR AND IFR CEILINGS WILL
HOLD OFF TILL 14Z TO 15Z. PRECIP WILL FALL THROUGH THE MORNING ACROSS
THE AREA LOWERING VIS TO MVFR AND IFR CONDITIONS ALONG WITH CEILINGS
REMAINING OVER THE AREA THROUGH THE REST OF THE TAF PERIOD. PRECIP
SHOULD END ACROSS EASTERN KENTUCKY BY 03Z WITH CEILINGS REMAINING
THROUGH THE REST OF THE TAF PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DUSTY
SHORT TERM...SHALLENBERGER
LONG TERM...JJ
AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
703 AM EST WED FEB 13 2013
.Forecast Update...
Issued at 655 AM EST Wed Feb 13 2013
We`re starting to see a rain/snow mix over southern Indiana and
portions of north central KY this morning including the Louisville
metro area. Updated the forecast to extend categorical POPs farther
north into southern Indiana with up to 1 inch of slushy accums
possible there as well. Radar imagery indicates moisture setting up
farther north than previously forecast. Latest RAP run has a good
handle on this. Will update and continue the SPS for this event.
&&
.Short Term (Now through Thursday)...
Issued at 325 AM EST Wed Feb 13 2013
...Light Slushy Snow Accumulations Possible Today...
As of 745Z, an upper trough was over MO with sfc low pressure over
the Gulf States. Precipitation associated with this system
stretched from western KY to eastern OK as of 745Z with rain
observed over most areas ESE of the upper trough and snow or a
rain/snow mix observed over portions of OK/MO/AR in the upper level
trough. The 6Z NAM12 and last few RAP runs seem to have the best
handle on the area of precipitation and general schematic of ptype.
Overall timing of the best precip and forcing seems to be a little
earlier than previously thought. Looks like the best dynamics and
precip should fall over our region between 12-18Z. Also, the latest
runs of the NAM and RAP have moved the best band of moderate to
heavy precip...probably a heavy wet snow as observed out in MO...to
the north. According to these models, the best snow band in which
we could see 1-2 inches of wet, slushy snow would be in a corridor
along the Ohio River to along the Western KY and Bluegrass
Parkways. Other areas over southern Indiana and south central KY
may see a brief mix of rain/snow...enough to create a dusting to a
half inch before quickly melting off. There is still some
uncertainty in where the band of moderate to heavy snow will set up
so stay tuned to morning forecast updates. Also, because of the
uncertainty, will continue with the SPS product instead of going
with an advisory although one may be needed later this morning.
So for today expect light rain to overspread the area before sunrise
with possibly some snow grains mixing in over southern Indiana and
northern KY at precip onset due to a deeper cold layer. After
sunrise we`ll start to see colder air filter in with the upper
trough causing precip to change over to a rain/snow mix and then
probably all snow for a time over southern Indiana and central KY.
The morning hours after sunrise through early afternoon will be the
best time for a period of moderate to heavy wet snow resulting in
slushy snow accumulations as high as 1-2 inches over north central
KY. This period of wintry precip may cause some travel issues.
We`ll continue to see a early afternoon before precip exits to our
east by late afternoon/early evening. Once snow comes to an end
over any location, quick melting can be expected as sfc temps are
expected to be above freezing today. In fact, most locations will
still top out in the upper 30s to lower 40s this afternoon despite
any morning/early afternoon snow.
For tonight and Thurs, expect dry conditions with partly cloudy
skies. Low temps will be in the upper 20s to lower 30s tonight. An
upper level trough and cold front will approach the region by Thurs
evening. Ahead of the trough, though, Thurs will be quite warm with
a strong southerly flow in place. High temps Thurs should be in the
low to mid 50s.
.Long Term (Thursday Night - Tuesday)...
Issued at 320 AM EST Wed Feb 13 2013
...A few shots for snow showers followed by a warm up and another
strong storm system early next week...
A lead shortwave will move across the Great Lakes on Thursday night,
with the associated surface system dragging a moisture starved cold
frontal boundary through the region. A secondary shortwave will
quickly move across the Ohio Valley on Friday as overall trough
envelopes the eastern CONUS. Friday looks to be the best setup for
some snow showers across the area as enough deep moisture combines
with steep low and mid level lapse rates, and an upslope surface
component. Soundings for this time period do show some convective
instability with saturation well into the -10 -20 C range across
northern portions of the CWA. Surface temperatures may squeak into
the mid and upper 30s on Friday, however thermal profile will be
easily cold enough for all snow showers below 40 degrees, some of
which could produce bursts of heavy snow and gusty winds.
At this point, best location for snow looks to be across southern
Indiana and north central Kentucky. As was mentioned in the previous
forecast, these snow showers have the potential to cause an impact
across the region with very light but quick accumulations. This setup
will have to be monitored.
We should see a lull in the activity on Friday night with subsidence
behind the quickly departing shortwave. Temperatures will be much
cooler with lows dropping into the mid 20s. By Saturday, confidence
is low as to exact placement of trough axis. Models are still having
trouble with the timing/placement of individual waves and the
overall progression of the east CONUS trough amplification. Have
continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble
mean consensus agree on an eastern solution with subsidence aloft
already in place across the Ohio Valley on Saturday. The less
consistent ECMWF still holds the axis to the west. Will only mention
a slight chance of a snow shower east of I-65 to account for this.
May be able to go completely dry for Saturday with the next set of
model runs. Temperatures will be cooler than Friday with highs only
topping out in the low and mid 30s.
Saturday night/Sunday morning will be the coldest of the period as
lows drop to around 20. Radiational cooling conditions will not be
optimal as surface winds stay up a bit and some upper level clouds
look to stream overhead. Therefore, cannot drop low too near dew
points that will be in the lower teens. May be able to decouple a
few of the coolest spots into the upper teens but the upper level
cloud cover should mostly mitigate this.
Saturday night through most of Monday should be dry as surface high
pressure holds over the area and weak upper level ridging holds.
Sunday will begin the warming trend with highs warming into the mid
30s to low 40s. Highs on Monday will be much milder with a return of
southerly flow. The mercury should rebound to the low 50s in most
spots.
By Monday afternoon we will begin to focus on the next storm system
that looks to impact the area through Tuesday. This system will
develop as a lee surface low intensifies ahead of a digging trough
over the central Plains. At this point the low looks to move from
the southern Plains, northeastward either into the Ohio Valley or
just north to the lower Great Lakes through Tuesday morning. This
warmer solution would bring overrunning rain showers to the area
late Monday afternoon, with more widespread rain moving into the
area Monday night and early Tuesday. Temperatures will likely crash
quickly behind the system on Tuesday afternoon as sharp trough moves
through and may eventually have to mention rain changing to snow.
Will stick with all rain for now as it is too early to mention these
details, especially with the low track in question. Will also leave
any thunder mention out of the forecast with the bulk of the
precipitation as any moisture return/instability would be limited by
short duration of southerly flow. This system will have to be
watched however, as a more northerly solution or deeper sfc low
would change the instability picture. Also, chose to disregard the
more southern solution offered by the operational ECMWF. This seems
to be the outlier, with a general consensus between the GFS/GEM/GFS
ensemble mean/ECMWF ensemble mean of a northern solution.
&&
.Aviation (12Z TAF Issuance)...
Issued at 605 AM EST Wed Feb 13 2013
An upper level trough will pass through the area today with a sfc
low pressure passing to our south. Precipitation associated with
this weather system has already begun to spread northward into
central KY this morning. At the beginning of TAF time, it should be
raining near all TAF sites with SDF/LEX rains being more
intermittent showers until deeper moisture overtakes the low level
dry layer. After sunrise, good forcing will enter the region
causing steady moderate banded precip over the region. It`s hard to
say whether a moderate band will affect the TAF sites, but at least
feel confident enough to include lower MVFR conditions this morning
through early afternoon as the heavier precip moves through the
region. Some IFR cigs may be possible in some of the heavier bands
of precip especially near BWG but will not include in the TAF at
this time as confidence is low. Rain is expected to be the
predominant precip type for BWG, however, SDF/LEX could see a RASN
mix in a moderate band. A RASN mix isn`t out of the realm of
possibilities for BWG either, but seems most likely at SDF/LEX at
this time. Will need to adjust as the precip bands set up this
morning and move closer to our area. By mid to late afternoon,
precip should move east of the TAF sites with conditions returning
to high end MVFR and then VFR by this evening.
Winds will be predominantly NNE as the weather system moves through
the area this morning through mid afternoon. Winds will strengthen
throughout the day likely exceeding 7kt at times. Winds will shift
to the WNW behind this system by this evening.
NAM model soundings indicate a layer of low level moisture for
tomorrow morning which could indicate a light fog or low cigs. Will
not place flight restrictions at the end of the TAFs for now, but it
will be something to investigate further.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......AMS
Long Term........BJS
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS JACKSON KY
658 AM EST WED FEB 13 2013
.UPDATE...
ISSUED AT 658 AM EST WED FEB 13 2013
CURRENT CONDITIONS ACROSS EASTERN KENTUCKY HAVE PRECIP MOVING INTO
THE AREA WITH RAIN REACHING THE GROUND IN THE SOUTH. HAVE UPDATED TO
FINE TUNE POPS AND ANY COOLING EFFECTS TO TEMPS FROM THE RAINFALL.
UPSTREAM...IT SEEMS THE BAND SETTING UP WILL STAY JUST NORTH SO WILL
KEEP CURRENT SNOWFALL FORECAST IN PLACE. ONLY CONCERN RIGHT NOW IS
THE COOLING EFFECTS AND SURFACE TEMPS OVER THE SOUTH AS SOME REPORTS
OF MODERATE RAIN POSSIBLY REALLY COOLING SURFACE TEMPS. WILL BANK ON
SURFACE TEMPS STAYING WARM ENOUGH THROUGH THE EARLY AFTERNOON BEFORE
THE COLD AIR FINALLY CHANGES THE RAIN OVER THIS AFTERNOON.
ALSO...MODEL SOUNDINGS CONTINUE TO SHOW DRY AIR AIR AT THE 10 DEGREE
CELSIUS TEMPS AND HIGHER SO WILL KEEP THE INCH OR SNOW FORECAST NORTH
OF THE MOUNTAIN PARKWAY AND IN THE HIGHEST ELEVATIONS SO NO NEW ZFP
WAS NEEDED.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 423 AM EST WED FEB 13 2013
CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER
EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH
CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES
ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER
30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY
ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP
INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY
SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND
SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN
IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A
BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION
OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF
HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND
GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT
WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING
MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE
GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO
RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE
SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND
INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A
RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE
HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS
STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE
EVENT...LOCATED FROM THE JKL POINT AND SOUTH.
BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH
POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN
ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A
BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA.
FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH
THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS
EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA
WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR
THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO
THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 341 AM EST WED FEB 13 2013
THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH
EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK
FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND
SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A
LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE
EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS
EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS
POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA.
THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF
ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF
HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS
THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING
ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL
BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS.
DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE
PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG
IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL
BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE
TEMPERATURE FORECAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 658 AM EST WED FEB 13 2013
WITH STILL A DRY LOWER LAYER TO OVERCOME...MVFR AND IFR CEILINGS WILL
HOLD OFF TILL 14Z TO 15Z. PRECIP WILL FALL THROUGH THE MORNING ACROSS
THE AREA LOWERING VIS TO MVFR AND IFR CONDITIONS ALONG WITH CEILINGS
REMAINING OVER THE AREA THROUGH THE REST OF THE TAF PERIOD. PRECIP
SHOULD END ACROSS EASTERN KENTUCKY BY 03Z WITH CEILINGS REMAINING
THROUGH THE REST OF THE TAF PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SHALLENBERGER
SHORT TERM...SHALLENBERGER
LONG TERM...JJ
AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
609 AM EST WED FEB 13 2013
...Updated Aviation Discussion...
.Short Term (Now through Thursday)...
Issued at 325 AM EST Wed Feb 13 2013
...Light Slushy Snow Accumulations Possible Today...
As of 745Z, an upper trough was over MO with sfc low pressure over
the Gulf States. Precipitation associated with this system
stretched from western KY to eastern OK as of 745Z with rain
observed over most areas ESE of the upper trough and snow or a
rain/snow mix observed over portions of OK/MO/AR in the upper level
trough. The 6Z NAM12 and last few RAP runs seem to have the best
handle on the area of precipitation and general schematic of ptype.
Overall timing of the best precip and forcing seems to be a little
earlier than previously thought. Looks like the best dynamics and
precip should fall over our region between 12-18Z. Also, the latest
runs of the NAM and RAP have moved the best band of moderate to
heavy precip...probably a heavy wet snow as observed out in MO...to
the north. According to these models, the best snow band in which
we could see 1-2 inches of wet, slushy snow would be in a corridor
along the Ohio River to along the Western KY and Bluegrass
Parkways. Other areas over southern Indiana and south central KY
may see a brief mix of rain/snow...enough to create a dusting to a
half inch before quickly melting off. There is still some
uncertainty in where the band of moderate to heavy snow will set up
so stay tuned to morning forecast updates. Also, because of the
uncertainty, will continue with the SPS product instead of going
with an advisory although one may be needed later this morning.
So for today expect light rain to overspread the area before sunrise
with possibly some snow grains mixing in over southern Indiana and
northern KY at precip onset due to a deeper cold layer. After
sunrise we`ll start to see colder air filter in with the upper
trough causing precip to change over to a rain/snow mix and then
probably all snow for a time over southern Indiana and central KY.
The morning hours after sunrise through early afternoon will be the
best time for a period of moderate to heavy wet snow resulting in
slushy snow accumulations as high as 1-2 inches over north central
KY. This period of wintry precip may cause some travel issues.
We`ll continue to see a early afternoon before precip exits to our
east by late afternoon/early evening. Once snow comes to an end
over any location, quick melting can be expected as sfc temps are
expected to be above freezing today. In fact, most locations will
still top out in the upper 30s to lower 40s this afternoon despite
any morning/early afternoon snow.
For tonight and Thurs, expect dry conditions with partly cloudy
skies. Low temps will be in the upper 20s to lower 30s tonight. An
upper level trough and cold front will approach the region by Thurs
evening. Ahead of the trough, though, Thurs will be quite warm with
a strong southerly flow in place. High temps Thurs should be in the
low to mid 50s.
.Long Term (Thursday Night - Tuesday)...
Issued at 320 AM EST Wed Feb 13 2013
...A few shots for snow showers followed by a warm up and another
strong storm system early next week...
A lead shortwave will move across the Great Lakes on Thursday night,
with the associated surface system dragging a moisture starved cold
frontal boundary through the region. A secondary shortwave will
quickly move across the Ohio Valley on Friday as overall trough
envelopes the eastern CONUS. Friday looks to be the best setup for
some snow showers across the area as enough deep moisture combines
with steep low and mid level lapse rates, and an upslope surface
component. Soundings for this time period do show some convective
instability with saturation well into the -10 -20 C range across
northern portions of the CWA. Surface temperatures may squeak into
the mid and upper 30s on Friday, however thermal profile will be
easily cold enough for all snow showers below 40 degrees, some of
which could produce bursts of heavy snow and gusty winds.
At this point, best location for snow looks to be across southern
Indiana and north central Kentucky. As was mentioned in the previous
forecast, these snow showers have the potential to cause an impact
across the region with very light but quick accumulations. This setup
will have to be monitored.
We should see a lull in the activity on Friday night with subsidence
behind the quickly departing shortwave. Temperatures will be much
cooler with lows dropping into the mid 20s. By Saturday, confidence
is low as to exact placement of trough axis. Models are still having
trouble with the timing/placement of individual waves and the
overall progression of the east CONUS trough amplification. Have
continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble
mean consensus agree on an eastern solution with subsidence aloft
already in place across the Ohio Valley on Saturday. The less
consistent ECMWF still holds the axis to the west. Will only mention
a slight chance of a snow shower east of I-65 to account for this.
May be able to go completely dry for Saturday with the next set of
model runs. Temperatures will be cooler than Friday with highs only
topping out in the low and mid 30s.
Saturday night/Sunday morning will be the coldest of the period as
lows drop to around 20. Radiational cooling conditions will not be
optimal as surface winds stay up a bit and some upper level clouds
look to stream overhead. Therefore, cannot drop low too near dew
points that will be in the lower teens. May be able to decouple a
few of the coolest spots into the upper teens but the upper level
cloud cover should mostly mitigate this.
Saturday night through most of Monday should be dry as surface high
pressure holds over the area and weak upper level ridging holds.
Sunday will begin the warming trend with highs warming into the mid
30s to low 40s. Highs on Monday will be much milder with a return of
southerly flow. The mercury should rebound to the low 50s in most
spots.
By Monday afternoon we will begin to focus on the next storm system
that looks to impact the area through Tuesday. This system will
develop as a lee surface low intensifies ahead of a digging trough
over the central Plains. At this point the low looks to move from
the southern Plains, northeastward either into the Ohio Valley or
just north to the lower Great Lakes through Tuesday morning. This
warmer solution would bring overrunning rain showers to the area
late Monday afternoon, with more widespread rain moving into the
area Monday night and early Tuesday. Temperatures will likely crash
quickly behind the system on Tuesday afternoon as sharp trough moves
through and may eventually have to mention rain changing to snow.
Will stick with all rain for now as it is too early to mention these
details, especially with the low track in question. Will also leave
any thunder mention out of the forecast with the bulk of the
precipitation as any moisture return/instability would be limited by
short duration of southerly flow. This system will have to be
watched however, as a more northerly solution or deeper sfc low
would change the instability picture. Also, chose to disregard the
more southern solution offered by the operational ECMWF. This seems
to be the outlier, with a general consensus between the GFS/GEM/GFS
ensemble mean/ECMWF ensemble mean of a northern solution.
&&
.Aviation (12Z TAF Issuance)...
Issued at 605 AM EST Wed Feb 13 2013
An upper level trough will pass through the area today with a sfc
low pressure passing to our south. Precipitation associated with
this weather system has already begun to spread northward into
central KY this morning. At the beginning of TAF time, it should be
raining near all TAF sites with SDF/LEX rains being more
intermittent showers until deeper moisture overtakes the low level
dry layer. After sunrise, good forcing will enter the region
causing steady moderate banded precip over the region. It`s hard to
say whether a moderate band will affect the TAF sites, but at least
feel confident enough to include lower MVFR conditions this morning
through early afternoon as the heavier precip moves through the
region. Some IFR cigs may be possible in some of the heavier bands
of precip especially near BWG but will not include in the TAF at
this time as confidence is low. Rain is expected to be the
predominant precip type for BWG, however, SDF/LEX could see a RASN
mix in a moderate band. A RASN mix isn`t out of the realm of
possibilities for BWG either, but seems most likely at SDF/LEX at
this time. Will need to adjust as the precip bands set up this
morning and move closer to our area. By mid to late afternoon,
precip should move east of the TAF sites with conditions returning
to high end MVFR and then VFR by this evening.
Winds will be predominantly NNE as the weather system moves through
the area this morning through mid afternoon. Winds will strengthen
throughout the day likely exceeding 7kt at times. Winds will shift
to the WNW behind this system by this evening.
NAM model soundings indicate a layer of low level moisture for
tomorrow morning which could indicate a light fog or low cigs. Will
not place flight restrictions at the end of the TAFs for now, but it
will be something to investigate further.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......AMS
Long Term........BJS
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS JACKSON KY
422 AM EST WED FEB 13 2013
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 423 AM EST WED FEB 13 2013
CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER
EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH
CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES
ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER
30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY
ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP
INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY
SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND
SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN
IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A
BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION
OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF
HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND
GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT
WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING
MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE
GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO
RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE
SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND
INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A
RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE
HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS
STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE
EVENT...LOCATED FROM THE JKL POINT AND SOUTH.
BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH
POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN
ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A
BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA.
FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH
THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS
EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA
WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR
THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO
THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 341 AM EST WED FEB 13 2013
THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH
EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK
FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND
SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A
LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE
EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS
EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS
POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA.
THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF
ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF
HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS
THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING
ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL
BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS.
DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE
PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG
IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL
BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE
TEMPERATURE FORECAST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 151 AM EST WED FEB 13 2013
WITH STILL A DRY LOWER LAYER TO OVERCOME...MVFR AND IFR CEILINGS WILL
HOLD OFF TILL NEAR DAY BREAK FOR TAF SITES. PRECIP WILL FALL AFTER
12Z ACROSS THE AREA LOWERING VIS TO MVFR AND IFR CONDITIONS ALONG
WITH CEILINGS REMAINING OVER THE AREA THROUGH THE REST OF THE TAF
PERIOD. PRECIP SHOULD END ACROSS EASTERN KENTUCKY BY 03Z WITH
CEILINGS REMAINING THROUGH THE REST OF THE TAF PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SHALLENBERGER
LONG TERM...SHALLENBERGER
AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
329 AM EST WED FEB 13 2013
.Short Term (Now through Thursday)...
Issued at 325 AM EST Wed Feb 13 2013
...Light Slushy Snow Accumulations Possible Today...
As of 745Z, an upper trough was over MO with sfc low pressure over
the Gulf States. Precipitation associated with this system
stretched from western KY to eastern OK as of 745Z with rain
observed over most areas ESE of the upper trough and snow or a
rain/snow mix observed over portions of OK/MO/AR in the upper level
trough. The 6Z NAM12 and last few RAP runs seem to have the best
handle on the area of precipitation and general schematic of ptype.
Overall timing of the best precip and forcing seems to be a little
earlier than previously thought. Looks like the best dynamics and
precip should fall over our region between 12-18Z. Also, the latest
runs of the NAM and RAP have moved the best band of moderate to
heavy precip...probably a heavy wet snow as observed out in MO...to
the north. According to these models, the best snow band in which
we could see 1-2 inches of wet, slushy snow would be in a corridor
along the Ohio River to along the Western KY and Bluegrass
Parkways. Other areas over southern Indiana and south central KY
may see a brief mix of rain/snow...enough to create a dusting to a
half inch before quickly melting off. There is still some
uncertainty in where the band of moderate to heavy snow will set up
so stay tuned to morning forecast updates. Also, because of the
uncertainty, will continue with the SPS product instead of going
with an advisory although one may be needed later this morning.
So for today expect light rain to overspread the area before sunrise
with possibly some snow grains mixing in over southern Indiana and
northern KY at precip onset due to a deeper cold layer. After
sunrise we`ll start to see colder air filter in with the upper
trough causing precip to change over to a rain/snow mix and then
probably all snow for a time over southern Indiana and central KY.
The morning hours after sunrise through early afternoon will be the
best time for a period of moderate to heavy wet snow resulting in
slushy snow accumulations as high as 1-2 inches over north central
KY. This period of wintry precip may cause some travel issues.
We`ll continue to see a early afternoon before precip exits to our
east by late afternoon/early evening. Once snow comes to an end
over any location, quick melting can be expected as sfc temps are
expected to be above freezing today. In fact, most locations will
still top out in the upper 30s to lower 40s this afternoon despite
any morning/early afternoon snow.
For tonight and Thurs, expect dry conditions with partly cloudy
skies. Low temps will be in the upper 20s to lower 30s tonight. An
upper level trough and cold front will approach the region by Thurs
evening. Ahead of the trough, though, Thurs will be quite warm with
a strong southerly flow in place. High temps Thurs should be in the
low to mid 50s.
.Long Term (Thursday Night - Tuesday)...
Issued at 320 AM EST Wed Feb 13 2013
...A few shots for snow showers followed by a warm up and another
strong storm system early next week...
A lead shortwave will move across the Great Lakes on Thursday night,
with the associated surface system dragging a moisture starved cold
frontal boundary through the region. A secondary shortwave will
quickly move across the Ohio Valley on Friday as overall trough
envelopes the eastern CONUS. Friday looks to be the best setup for
some snow showers across the area as enough deep moisture combines
with steep low and mid level lapse rates, and an upslope surface
component. Soundings for this time period do show some convective
instability with saturation well into the -10 -20 C range across
northern portions of the CWA. Surface temperatures may squeak into
the mid and upper 30s on Friday, however thermal profile will be
easily cold enough for all snow showers below 40 degrees, some of
which could produce bursts of heavy snow and gusty winds.
At this point, best location for snow looks to be across southern
Indiana and north central Kentucky. As was mentioned in the previous
forecast, these snow showers have the potential to cause an impact
across the region with very light but quick accumulations. This setup
will have to be monitored.
We should see a lull in the activity on Friday night with subsidence
behind the quickly departing shortwave. Temperatures will be much
cooler with lows dropping into the mid 20s. By Saturday, confidence
is low as to exact placement of trough axis. Models are still having
trouble with the timing/placement of individual waves and the
overall progression of the east CONUS trough amplification. Have
continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble
mean consensus agree on an eastern solution with subsidence aloft
already in place across the Ohio Valley on Saturday. The less
consistent ECMWF still holds the axis to the west. Will only mention
a slight chance of a snow shower east of I-65 to account for this.
May be able to go completely dry for Saturday with the next set of
model runs. Temperatures will be cooler than Friday with highs only
topping out in the low and mid 30s.
Saturday night/Sunday morning will be the coldest of the period as
lows drop to around 20. Radiational cooling conditions will not be
optimal as surface winds stay up a bit and some upper level clouds
look to stream overhead. Therefore, cannot drop low too near dew
points that will be in the lower teens. May be able to decouple a
few of the coolest spots into the upper teens but the upper level
cloud cover should mostly mitigate this.
Saturday night through most of Monday should be dry as surface high
pressure holds over the area and weak upper level ridging holds.
Sunday will begin the warming trend with highs warming into the mid
30s to low 40s. Highs on Monday will be much milder with a return of
southerly flow. The mercury should rebound to the low 50s in most
spots.
By Monday afternoon we will begin to focus on the next storm system
that looks to impact the area through Tuesday. This system will
develop as a lee surface low intensifies ahead of a digging trough
over the central Plains. At this point the low looks to move from
the southern Plains, northeastward either into the Ohio Valley or
just north to the lower Great Lakes through Tuesday morning. This
warmer solution would bring overrunning rain showers to the area
late Monday afternoon, with more widespread rain moving into the
area Monday night and early Tuesday. Temperatures will likely crash
quickly behind the system on Tuesday afternoon as sharp trough moves
through and may eventually have to mention rain changing to snow.
Will stick with all rain for now as it is too early to mention these
details, especially with the low track in question. Will also leave
any thunder mention out of the forecast with the bulk of the
precipitation as any moisture return/instability would be limited by
short duration of southerly flow. This system will have to be
watched however, as a more northerly solution or deeper sfc low
would change the instability picture. Also, chose to disregard the
more southern solution offered by the operational ECMWF. This seems
to be the outlier, with a general consensus between the GFS/GEM/GFS
ensemble mean/ECMWF ensemble mean of a northern solution.
&&
.Aviation (06Z TAF Issuance)...
Issued at 1215 AM EST Wed Feb 13 2013
An upper level trough will pass through the area today with a sfc
low pressure passing to our south. Precipitation associated with
this weather system has already begun to spread northward into south
central KY early this morning. Although it`s having problems
overcoming a significant dry layer, we are finally getting some
reports of rain in western KY and northern TN. With decent radar
returns over BWG as of 5Z, will go ahead and start this TAF with
VCSH. As moisture spreads northward through the early morning
hours, we`ll see rains move into BWG around 8Z...LEX around
10Z...and SDF around 11Z respectively. By late morning, good
forcing will enter the region causing steady moderate banded precip
over the region. It`s hard to say whether a moderate band will
affect the TAF sites, but at least feel confident enough to include
lower MVFR conditions from mid morning through early afternoon as
the heavier precip moves through the region. Some IFR cigs may be
possible in some of the heavier bands of precip but will not include
in the TAF at this time as confidence is low. Rain is expected to be
the predominant precip type for SDF/BWG, however, LEX could see a
RASN mix in a moderate band. A RASN mix isn`t out of the realm of
possibilities for SDF/BWG either, but seems most likely at LEX at
this time. Will need to adjust as the precip bands set up this
morning and move closer to our area. By mid to late afternoon,
precip should move east of the TAF sites with conditions returning
to high end MVFR and then VFR by this evening.
Winds will be light and variable early this morning and then become
predominantly NNE as the weather system approaches our area just
before sunrise. Winds will strengthen throughout the day likely
exceeding 7kt this afternoon. Winds will shift to the WNW behind
this system by this evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......AMS
Long Term........BJS
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
605 PM EST THU FEB 14 2013
.AVIATION...
//DISCUSSION...
CENTER OF CLIPPER SHORTWAVE WILL PASS OVERHEAD EARLY IN THE FORECAST
WITH SCATTERED RAIN/SNOW SHOWERS ENDING EARLY WITH LAKE EFFECT SNOW
SHOWERS THEN DEVELOPING OVERNIGHT W/ WRAPAROUND CIGS IN MVFR RANGE.
PERIODIC LIGHT SNOW SHOWERS WILL BE POSSIBLE IN COLD...CYCLONIC
NORTHWEST FLOW THROUGH FRIDAY...BUT THIS ACTIVITY WILL BE VERY
SPORADIC THROUGH THIS FORECAST PERIOD.
FOR DTW...MVFR/LOWER VFR CIGS WILL FALL TO MVFR AOB 2000 FEET LATER
THIS EVENING AS MOISTURE WRAPS INTO AREA AROUND DEPARTING SHORTWAVE
TROUGH. WHILE CIGS MAY MIX HIGHER ON FRIDAY...MVFR CONDITIONS WILL
REMAIN THE RULE AS PERIODIC LIGHT LAKE EFFECT SNOW SHOWERS AFFECT
THE TERMINAL.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING HEIGHTS BELOW 5000 FEET THROUGHOUT MUCH
IF NOT ALL OF THE TAF PERIOD.
&&
.PREV DISCUSSION...ISSUED 359 PM EST THU FEB 14 2013
SHORT TERM...THIS EVENING AND TONIGHT
THE VORTICITY RICH POTENTIAL VORTICITY ANOMALY NOW SPINNING ACROSS
CENTRAL LAKE MICHIGAN HAS LED TO A NUMBER OF SPOKES/BANDS OF
PRECIPITATION SLIDING THROUGH LOWER MICHIGAN. SINCE MIDDAY THESE
BANDS HAVE BEEN NOTHING MORE THAN LIGHT RAIN SHOWERS OR SPRINKLES
PER SFC REPORTS AND A NEAR SURFACE MELTING LAYER AT GREATER THAN 4C.
VARIOUS HIRES MODELS ARE SUGGESTING THAT CONVECTION/SHOWER
DEVELOPMENT WILL TAKE PLACE ALONG AND AHEAD OF THE COLD FRONT
BETWEEN 21-00Z. THIS IDEA REMAINS VALID. DIFFICULT TO EVALUATE THE
OVERALL THERMODYNAMIC PROFILE OR HOW MUCH CAPE IS OUT THERE WITH THE
VALID RUC BASED SPC MESOANALYSIS GRAPHIC SHOWING NOTHING IN THE WAY
OF MUCAPE. GOING THROUGH MODEL DATA THOUGH SUGGESTS THAT 50 TO 100
J/KG IS PLAUSIBLE GIVEN SFC/DWPT VALUES THAT ARE ON TARGET.
EVOLUTION OF MODEL SOUNDINGS SUGGESTS THAT IT WILL REQUIRE SOME
COOLING FROM APPROACHING COLD FRONT TO ERODE A LOW CAPPING LAYER TO
ALLOW FOR INITIATION. THE POTENTIAL EXISTS FOR CONVECTION TO YIELD
GRAUPEL/ICE PELLETS. ADDITIONALLY...THERE REMAINS A POSSIBILITY THAT
BURSTS COULD PRODUCE MORE IN THE WAY OF SNOW...AND THE PERCENTAGE OF
OCCURRENCE IS AN UNKNOWN. FARTHER NORTH...EXPECTING THE ACTIVITY TO
FALL AS RAIN...ALTHOUGH THIS AREAS STANDS A BETTER CHANCE TO SEE
SOME LIGHT SNOW WITH MINOR ACCUMULATIONS. WINDS WILL INCREASE...UP
TO 25 TO 30 MPH...AS WIND DIRECTIONS SHIFT FROM 200 TO 240 POST COLD
FRONT.
ISENTROPIC DOWNGLIDE WILL COMMENCE BETWEEN 00-03Z...KICKING IT UP A
COUPLE OF GEARS BETWEEN 03-09Z. THE COLUMN IS SHOWN TO BECOME QUITE
STABLE IN THE 900-700MB LAYER...TOO STABLE TO SUPPORT MUCH IN THE
WAY OF SNOW TONIGHT. NAM IS HIGHLIGHTING SOME LAKE EFFECT
BANDING/ENHANCED CONVERGENCE ACROSS SW LOWER LATE TONIGHT. DID LEAVE
A LOW CHANCE FOR LIGHT IN ACROSS THE SOUTH AS THERE IS SOME
POTENTIAL FOR SOME SNOWFLAKES TO MAKE THE TRIP ACROSS THE PENINSULA.
OTHERWISE...FLURRIES FOR A MAJORITY OF THE AREA. LOWS TONIGHT WERE
DERIVED FROM A BLEND OF RAW MODEL OUTPUT...A DECENT ADJUSTMENT
DOWNWARD UPPER TEENS NORTH TO UPPER 20S SOUTH.
LONG TERM...FRIDAY THROUGH NEXT THURSDAY
LONGWAVE TROUGH WILL LOCK COOL AIR IN PLACE OVER THE GREAT LAKES
THROUGH THE WEEKEND...AS H850 TEMPS DROP TO AROUND -18C (BY SAT
NIGHT) IN THE POST-FRONTAL AIRMASS. CHANCES FOR ACCUMULATING SNOW
LOOK FAIRLY LOW FOR THIS SIDE OF THE STATE...AND WILL BE DUE TO A
COMBINATION OF WEAK SHORTWAVES AND LAKE EFFECT. SHORTWAVES MAY BE A
LITTLE HARD TO TIME DUE TO SMALL NATURE AND LACK OF SAMPLING (AT
THIS TIME) AND FORECAST ADJUSTMENTS ARE STILL POSSIBLE AS CHANGES IN
TIMING/LOCATION OF SHORTWAVES IMPACT LAKE EFFECT PARAMETERS SUCH AS
STABILITY...MOISTURE...AND WIND SPEED AND TRAJECTORY.
MODEL GUIDANCE TAKES THE WAVE NOW DROPPING THROUGH SOUTHERN MANITOBA
ACROSS NORTHERN LOWER MICHIGAN TOMORROW...WHILE ALSO SHEARING APART
ANOTHER SHORTWAVE AS IT DROPS FROM THE DAKOTAS DOWN INTO THE OHIO
VALLEY. VERY WEAK LIFT ASSOCIATED WITH THESE WAVES COULD PROVIDE A
BRIEF SNOW SHOWER TO THE AREA...BUT MAINLY EXPECT A LOT OF CLOUDS
AND FLURRIES AROUND DUE TO LAKE EFFECT AND STEEP LAPSE RATES. DID
KEEP LOW POPS IN THE FORECAST...BUT THINK FAIRLY WEAK FLOW OVER THE
LAKE AND ONLY MODERATE INSTABILITY SHOULD KEEP ACCUMULATIONS TO OUR
WEST. SIMILAR POP FORECAST EXISTS ON FRIDAY NIGHT. ALTHOUGH MOISTURE
DEPTH AND COLD AIR ADVECTION WILL INCREASE...MEAN SURFACE-850MB FLOW
ACROSS LAKE MICHIGAN WILL ONLY RUN 10-15 KNOTS...AND WILL TURN A
LITTLE MORE TO THE NORTHWEST. AGAIN WOULD EXPECT MOSTLY
FLURRIES...AND ONLY LOW CHANCES FOR LIGHT ACCUMULATIONS SOUTH OF A
LINE FROM HOWELL TO DETROIT.
POTENTIAL FOR LIGHT SNOW LOOKS A LITTLE BETTER ON SATURDAY AS A
SHORTWAVE TROUGH AXIS CLIPS ACROSS THE AREA. LAKE EFFECT ENHANCEMENT
ALSO LOOKS MORE LIKELY AS EQUILIBRIUM HEIGHTS OVER LAKE
MICHIGAN HIT THEIR PEAK AROUND 12KFT AND LAKE TO H850 DELTA T VALUES
RISE TO OVER 20 C. LIMITING FACTORS FOR THIS SIDE OF THE STATE ONCE
AGAIN WILL BE LIGHT FLOW AND WINDS TURNING MORE TO THE
NORTH-NORTHWEST. WOULD EXPECT FLURRIES AND SCATTERED LIGHT SNOW
SHOWERS ACROSS THE AREA IN THIS SET-UP...WITH BETTER POTENTIAL
(HIGHER POPS) SOUTH OF M-59 WHERE CONVERGENCE SHOULD BE BETTER.
LONGWAVE TROUGH WILL PUSH TO THE EAST COAST DURING THE SECOND HALF
OF THE WEEKEND...ALLOWING AN UPSTREAM RIDGE TO SLIDE IN OVERHEAD
SUNDAY INTO MONDAY. ENERGY DIVING OUT OF THE GULF OF ALASKA WILL
DROP THROUGH THE CENTRAL ROCKIES MONDAY...PULLING ADDITIONAL ENERGY
OUT OF THE SOUTHERN STREAM BEFORE IT BECOMES MORE ORGANIZED AND
DEEPENS OVER THE GREAT LAKES MONDAY NIGHT AND TUESDAY (AIDED BY GOOD
HEIGHT FALLS AND STRONG JET DYNAMICS). TRENDS WITH THE EURO AND GFS
HAVE BEEN TO SHIFT THIS SYSTEM FURTHER NORTH OVER THE PAST 24
HOURS...WITH A SURFACE LOW CENTER TRACK MORE ACROSS CENTRAL OR
NORTHERN MICHIGAN. GIVEN THAT THE GEM AND UKMET ARE STILL FURTHER
SOUTH WITH THE TRACK...MADE JUST MINOR ADJUSTMENTS TO PRECIPITATION
TYPE THIS FORECAST CYCLE TO INCREASE RAIN POTENTIAL. 14.12Z EURO/GFS
SOLUTIONS NOW SUPPORT ALL RAIN MONDAY NIGHT BEFORE A CHANGEOVER TO
SNOW BEHIND A STRONG COLD FRONT ON TUESDAY. ACCUMULATIONS STILL LOOK
POSSIBLE...BUT MAY BE DELAYED UNTIL TUESDAY.
MARINE...
LOW PRESSURE WILL TRACK THROUGH LOWER MICHIGAN THIS AFTERNOON AND
ACROSS NORTHERN LAKE HURON THIS EVENING. CURRENT SURFACE
OBSERVATIONS IN THE INCREASED GRADIENT PORTION OF THE SURFACE LOW IS
SUPPORTING WIND GUSTS OF UP TO 30 KNOTS. WITH NO EXPECTED
DEEPENING/ACTUAL MIDLEVEL WEAKENING RATES WILL CANCEL THE GALE WATCH
AND FORGO A GALE WARNING. THIS IS ALSO SUPPORTED BY THE VERY BRIEF
DURATION TIME. HOWEVER...WITH THE COLD NORTHWEST FLOW FOLLOWING THE
CYCLONE...DID ISSUE A BRISK WIND ADVISORY FOR ALL NEARSHORE ZONES.
WINDS WILL WEAKEN ON FRIDAY AS ARCTIC HIGH PRESSURE BUILDS INTO THE
WESTERN GREAT LAKES REGION. THIS HIGH WILL KEEP RELATIVELY LIGHT
WINDS ON THE LAKES THROUGH THE WEEKEND. A LOW PRESSURE SYSTEM IS
FORECAST TO INTENSIFY OVER THE GREAT LAKES REGION MONDAY NIGHT INTO
TUESDAY AND WILL OFFER THE NEXT CHANCE FOR STRONG WINDS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
BRISK WIND ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING SAGINAW BAY...UNTIL 10 AM FRIDAY.
LAKE ST CLAIR...
BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY.
MI WATERS OF LAKE ERIE...
BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY.
&&
$$
AVIATION.....DG
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1250 AM EST WED FEB 13 2013
.SYNOPSIS...
ISSUED AT 415 PM EST TUE FEB 12 2013
WEAK HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT LAKES TONIGHT
AND WEDNESDAY. THIS PATTERN WILL GENERATE ABOVE NORMAL TEMPERATURES
AND OCCASIONAL FLURRIES...ACROSS THE NORTHERN MICHIGAN INTO THURSDAY.
HOWEVER...THE NEXT SYSTEM TO INFLUENCE THE GREAT LAKES ARRIVES
THURSDAY...BEFORE QUICKLY LIFTING NORTHEAST INTO QUEBEC FRIDAY. THIS
SYSTEM WILL GENERATE ANOTHER ROUND OF SNOW ACROSS NORTHERN
MICHIGAN THURSDAY...WHILE ALSO USHERING IN MUCH COLDER CONDITIONS
FRIDAY AND INTO THE WEEKEND. ACCUMULATING LAKE EFFECT SNOW CAN BE
EXPECTED OVER THE WESTERN GREAT LAKES THIS WEEKEND.
&&
.UPDATE...
ISSUED AT 1234 AM EST WED FEB 13 2013
LOW LEVEL STRATO CU LIKELY TO HANG ON THROUGH THE BALANCE OF THE
NIGHT WITH SHALLOW 925MB INSTABILITY HOLDS THROUGH 12Z...AND DUE
TO A NARROW CORRIDOR OF MID LEVEL MOISTURE SWEEPING OVERHEAD TO
GIVE IT A FIGHTING CHANCE. SOME BREAKS EXPECTED OUT THERE
HOWEVER...MAINLY GTV BAY AREA AND NE LOWER TOWARD DAYBREAK. QUIET
NIGHT. ALTHOUGH RELATIVELY INSIGNIFICANT...GOING AGAINST MODEL
SUGGESTIONS OF FLURRIES RE-FIRING IN WSW FLOW REGIMES AS SAID
MOISTURE SWEEPS IN OVERHEAD.
UPDATE ISSUED AT 930 PM EST TUE FEB 12 2013
FLURRIES HAVE TEMPORARILY ENDED ACROSS NW LWR MICHIGAN LATE THIS
EVENING THANKS TO BUILDING SUBSIDENCE AND SHALLOWING OF THE LOW
LEVEL MOIST LAYER. LATEST IR SATELLITE DOES SHOW A LINE OF COOLER
CLOUD TOPS OVER CENTRAL UPR MICHIGAN ASSOCIATED WITH A WEAK VORT
LOBE AND A NARROW BAND OF MID LEVEL MOISTURE. EXPECT THESE
FEATURES WILL LEND TO REDEVELOPMENT OF ADDITIONAL LAKE EFFECT
FLURRIES OVERNIGHT FOR FAR NRN AND NW LWR MICHIGAN AS WELL AS
PORTIONS OF ERN UPR MICHIGAN...STILL UNDER THE DIRECTION OF SW
LOW LEVEL FLOW. TEMPS CONTINUE TO FALL THRU THE 20S...ON THEIR WAY
TO THE UPPER TEENS AND LOWER 20S FOR OVERNIGHT LOWS.
UPDATE ISSUED AT 645 PM EST TUE FEB 12 2013
LAKE EFFECT FLURRIES CONTINUE TO STREAM INTO FAR NRN AND NW LWR
MICHIGAN THIS EVENING UNDER THE DIRECTION OF LOW LEVEL SW FLOW.
LOW CLOUDS REMAIN TRAPPED BELOW THE SUBSIDENCE INVERSION...
MAINTAINING OVC SKIES ACROSS OUR ENTIRE CWA EVEN AWAY FROM ANY
LAKE INFLUENCES. VERY LITTLE WILL CHANGE THRU THE NIGHT AS LOW
LEVEL MOISTURE/CLOUDS REMAINS STUCK BELOW THE INVERSION AND SW
FLOW CONTINUES TO PRODUCE FLURRIES FOR FAR NRN AND NW LWR
MICHIGAN. OVERNIGHT LOWS IN THE UPPER TEENS TO LOWER 20S LOOKS
REASONABLE GIVEN CURRENT SURFACE DWPTS IN THAT VCNTY.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 415 PM EST TUE FEB 12 2013
COLD AIR ADVECTION HAS ABOUT MAXED OUT BEHIND YESTERDAY`S DEPARTING
STORM...WITH LATEST HIGH RES RUC ANALYSIS PLACING CIRCA -11C H85
TEMPERATURES ACROSS THE NORTH WOODS. DESPITE EXCEEDINGLY LOW
INVERSIONS (H85 PER SAME RUC ANALYSIS)...MOISTURE DEPTH EXTENDING
TO THE LOW END OF THE FAVORED DGZ CONTINUES TO KICK OFF WIDESPREAD
FLURRIES IN FAVORED WEST FLOW LAKE AREAS. ABUNDANT LOW LEVEL
MOISTURE ALSO LEADING TO A MAINLY CLOUDY DAY...WITH ANY SUBSTANTIAL
CLEARING OF NOTE BACK ACROSS WISCONSIN. THIS CLEARING APPEARS TIED
TO DOWNWARD FORCING ON BACKSIDE OF RATHER COMPACT SHORTWAVE
PINWHEELING EAST INTO NORTHERN LAKE MICHIGAN. NO SIGNIFICANT
CONCERNS THROUGH THE SHORT TERM (WEDNESDAY)...ALTHOUGH LINGERING
FLURRIES AND CLOUD TRENDS WILL NEED ADDRESSING.
WISCONSIN SHORTWAVE WILL STEADILY AND RAPIDLY PUSH ACROSS THE AREA
THIS EVENING...AND LACK OF ANY APPRECIABLE MOISTURE SHOULD PRECLUDE
MUCH...IF ANY...LAKE OR SYNOPTIC RESPONSE. H85 TEMPERATURES SLOWLY
WARM IN DEVELOPING WEAK SOUTHWEST FLOW WAA REGIME...REACHING THE
NEGATIVE SINGLE DIGITS BY MORNING. NAM-WRF BUFFER SOUNDINGS SHOW LOW
LEVEL MOISTURE FALLING BELOW -10C ISOTHERM...WHICH COMBINED WITH
LOWERING DELTA T/S...WOULD SUPPORT A QUICK DEMISE TO ONGOING
FLURRIES. NOT WILLING TO BITE ON THIS JUST YET...AND PREFER TO KEEP
FLURRIES IN THE FORECAST...SIMPLY FOLLOWING THE WINDS FOR THERE
PLACEMENT (WHICH SUGGESTS THEY SHOULD CONFINE THEMSELVES IN FAVORED
SOUTHWEST FLOW AREAS THROUGH THE NIGHT). CLOUD COVER REMAINS A
FORMIDABLE CHALLENGE...ESPECIALLY GIVEN WHAT IS OCCURRING BEHIND
UPSTREAM WAVE. DO HAVE SOME TREPIDATION GOING TOO AGGRESSIVE WITH
CLOUDS OVERNIGHT...ESPECIALLY IN NON-FAVORED LAKE AREAS. SUBTLE WARM
ADVECTION AND POST-WAVE DOWNWARD RESPONSE JUST MAY WORK IN TANDEM TO
FORCE MUCH MORE CLEARING THAN THIS FORECAST WILL SUGGEST. WILL
TREND PARTLY CLOUDY ACROSS EASTERN UPPER AND NORTHEAST LOWER AS A
STARTING POINT...WITH KNOWLEDGE THAT COMPLETELY CLOUDY OR CLEAR IS
THE MORE LIKELY OUTCOME. TEMPERATURES...OF COURSE...HIGHLY DEPENDENT
ON HOW THIS WHOLE CLOUD THING UNFOLDS. MID AND UPPER TEENS MAY BE
SEVERAL DEGREES TOO "WARM". WE SHALL SEE.
SAME STORY HEADING INTO WEDNESDAY...WITH SOME LINGERING FLURRIES AND
MOSTLY TO PARTLY CLOUDY SKIES. LOW LEVEL MODIFICATION
CONTINUES...SUGGESTING HIGHS IN THE LOWER AND MIDDLE 30S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 415 PM EST TUE FEB 12 2013
MAIN FORECAST CONCERNS WILL BE POTENTIAL FOR ACCUMULATING LAKE
ENHANCED SNOWS STARTING THURSDAY AND CONTINUING INTO THE
WEEKEND.
THE LATEST HEMISPHERIC ANALYSIS SHOWS A STABLE 3-WAVE PATTERN WITH
LARGE SCALE TROUGHING OVER CENTERED OVER JAMES BAY...EAST ASIA
/AROUND 120E/ AND CENTRAL EUROPE. A VERY STRONG ZONAL JET REMAINS
OVER EAST ASIA AND THE WESTERN PACIFIC...WITH A SLIT FLOW OVER THE
EASTERN PACIFIC EXTENDING INTO THE WEST COAST. THE SPLIT FLOW MERGES
TO FORM A FASTER JET THE SOUTHEASTERN U.S.
THURSDAY...AN AMPLIFYING PATTERN IS EXPECTED WITH STRONG PACIFIC JET
TO BEEF UP THE WEST COAST RIDGE...RESULTING IN INCREASED TROUGHING
OVER THE EASTERN TWO THIRDS OF THE CONUS BY THURSDAY. SHORT WAVE
ENERGY IS EXPECTED TO ROUND THE TOP OF THE RIDGE ON
WEDNESDAY...BEFORE DIVING INTO THE GREAT LAKES BY THURSDAY. AN
ASSOCIATED SURFACE RESPONSE/CLIPPER SYSTEM WILL MOVE THOUGH THE
GREAT LAKES...BRINGING NORTHERN MICHIGAN THE NEXT CHANCE OF SOME
LIGHT SNOW. THE AMOUNT OF MOISTURE THIS SYSTEM HAS TO WORK WITH IS
NOT TERRIBLE...WITH MODEL SOUNDINGS SHOWING P-WATS OF AROUND 0.3 TO
0.4 INCHES ACROSS THE CWA. THE DEGREE OF FORCING REMAINS IN SOME
QUESTION...WITH TWO DISTINCT AREAS OF ENHANCED PVA EXPECTED TO MOVE
THROUGH THE REGION EMBEDDED IN THE SHEARED PIECE OF ENERGY. THE
NAM/GFS WANT TO SPIN UP A STRONGER LOW WITH THIS FEATURE...WHILE THE
ECMWF/GEM KEEP THE SURFACE LOW MORE BENIGN. PREFER THE LATTER OF THE
SOLUTIONS...GIVEN THAT THESE TWO PIECES OF ENERGY DO NOT NECESSARILY
PHASE TOGETHER. OVERALL LOOKING LIKE A 1 TO 2..PERHAPS LOCALLY 3
INCH SNOW EVENT. RAPIDLY CHANGING FLOW AND WARMISH AIR ALOFT WITH
H85 TEMPS BETWEEN -5 TO -8C LOOK TO KEEP A MAJOR DAMPER OF ANY LAKE
ENHANCEMENT. SNOW MAY BE ALSO BE SLOW TO ACCUMULATE ON ROAD SURFACES
WITH SURFACE TEMPS AT OR SLIGHTLY ABOVE FREEZING...WITH THE MORE
AGGRESSIVE NAM/GFS SUGGESTING HIGHS IN THE MID TO UPPER 30S FOR
THURSDAY. THIS WOULD HAVE RAIN/SNOW MIX IMPLICATIONS FOR THE LOWER
ELEVATIONS OF THE CWA...BUT PREFER THE MORE COOLER...LESS AMPLIFIED
SOLUTIONS FOR NOW.
THURSDAY NIGHT AND FRIDAY...FORCING BEGINS TO PUSH EAST OF THE AREA
BY LATE THURSDAY AFTERNOON WITH STRONG COLD AIR ADVECTION ENSUING
ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY. THIS WILL RAMP UP THE
LAKE EFFECT SNOW MACHINE DURING THIS TIMEFRAME. MODELS ARE NOT IN
THE BEST AGREEMENT WITH THE NAM/GFS MORE NORTHWESTERLY THAN THE NNW
FLOW DEPICTED BY THE ECMWF. MODEST INVERSION HEIGHTS AND DEEPEST
MOISTURE MOVING OUT SHOULD KEEP MAJOR LAKE SNOW ACCUMULATIONS IN
CHECK...HOWEVER SEVERAL INCHES OF ACCUMULATION LOOK LIKELY FOR THE
NW/NNW FAVORED SNOW BELTS THROUGH FRIDAY. H85 TEMPS FALL TO -15 TO
-18C DURING THE DAY FRIDAY...WITH MODEL CONSENSUS SHOWING HIGHS
STRUGGLING TO MAKE IT OUT OF THE TEENS.
FRIDAY NIGHT THROUGH TUESDAY...CHILLY CONDITIONS ENSUE AS DEEP
TROUGH SETTLES INTO THE GREAT LAKES WITH MODEL CONSENSUS SHOWING H85
TEMPS IN THE -18 TO -22 RANGE ACROSS THE GREAT LAKES INTO THE DAY ON
SATURDAY. CERTAINLY PLENTY OF INSTABILITY TO KEEP THE LAKE EFFECT
SNOW MACHINE GOING...WITH POCKETS OF DEEPER H85-H7 MOISTURE
ASSOCIATED WITH EMBEDDED SHORTWAVES ROUNDING THE LONGER WAVE TROUGH
AND CONTINUED NORTHWEST TO NORTH NORTHWEST FLOW. AT THE
LEAST...SEVERAL INCHES OF ACCUMULATION LOOK LIKELY IN THE NW TO NNW
FAVORED SNOW BELTS WITH THIS PATTERN. LOOKING AT SOME OF COOP
SNOWFALL GUIDANCE FROM THE CIPS ANALOGS FOR THE 72 HOUR PERIOD
CENTERED ON 00Z/17 SHOWS HEAVY ACCUMULATIONS FOR 3 OF THE TO 5
ANALOGS. STILL PLENTY OF DETAILS TO WORK OUT BETWEEN NOW AND THIS
WEEKEND...WITH ICE COVER OVER NORTHERN LAKE MICHIGAN AND MODEST
INVERSION HEIGHTS SERVING AS MITIGATING FACTORS FOR HEAVY
ACCUMULATIONS. STILL COULD SEE THE POSSIBILITY OF SOME HEADLINES FOR
THE FRI/SAT TIMEFRAME...AND WILL MAINTAIN THE THREAT FOR
ACCUMULATING LAKE SNOWS IN THE HWO.
SUNDAY THROUGH MONDAY...PROGRESSIVE PATTERN CONTINUES WITH DEEP
TROUGH KICKING OFF TO THE NORTHEAST AND HEIGHTS MODIFYING
SUBSTANTIALLY AS UPSTREAM RIDGING BUILDS INTO THE GREAT LAKES.
1000-850 MEAN FLOW IS PROGGED TO BACK TO THE SOUTHWEST WITH H85
TEMPS MODIFYING ENOUGH TO END THE LES THREAT...ALTHOUGH THERE MAY BE
SOME LINGER -SHSN FOR SW FAVORED FLOW AREAS INITIALLY SUNDAY
MORNING. ANOTHER CLIPPER SYSTEM LOOKS TO TRAVERSE THE AREA SUNDAY
NIGHT INTO MONDAY...HOWEVER THE BETTER MOISTURE AND FORCING LOOK TO
REMAIN OVER THE NORTHERN PORTION OF THE CWA ATTM.
MONDAY NIGHT INTO TUESDAY...NEXT TROUGH BUILDS INTO THE GREAT LAKES
WITH GFS/ECMWF DEPICTING A STORM SYSTEM DEVELOPING IN THE SOUTHERN
PLAINS AND MOVING UP THROUGH THE OHIO VALLEY INTO THE GREAT LAKES.
NOT A LOT OF CONFIDENCE OF COURSE THIS FAR OUT...ESPECIALLY WHEN
LOOKING AT SOME OF THE ENSEMBLE GUIDANCE ON THE UPPER AIR
PATTERN...BUT SOME SIGNALS ARE THERE OF SAID SYSTEM WHEN LOOKING AT
THE REANALYSIS BASED ON THE TOP GFS/CAN ENS TOP ANALOGS. SOMETHING
THAT WILL CERTAINLY NEED TO BE MONITORED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1234 AM EST WED FEB 13 2013
MVFR CIGS LIKELY TO HANG ON THROUGH MUCH OF THE NIGHT...AND
EVEN INTO A FEW HOURS AFTER DAYBREAK. THIS AIDED BY SHALLOW
OVERLAKE INSTABILITY AND WEAK DISTURBANCE/CORRIDOR OF MID LEVEL
MOISTURE ALOFT SWEEPING THROUGH. DO BELIEVE THE MVFR CIGS WILL MIX
OUT...ALTHOUGH WINDS/MIXING NOT SO IMPRESSIVE HEADING INTO
TOMORROW. WILL GO VFR WITH BROKEN MID/HIGH CLOUD AROUND FOR MUCH
OF THE DAY AND INTO THE EVENING. AN ALBERTA CLIPPER ARRIVES LATE
TOMORROW NIGHT...BRINGING POSSIBLE SNOWS AND MVFR CIGS BACK INTO
NW LOWER AFTER THE TAF PERIOD.
WINDS WILL BE RELATIVELY LIGHT OUT OF THE SW.
&&
.MARINE...
ISSUED AT 415 PM EST TUE FEB 12 2013
MARINE...VEERING WINDS TO SOUTHWEST REMAIN SOMEWHAT GUSTY HEADING
INTO THIS EVENING. MAY EVEN SEE SOME SCA PRODUCING GUSTS ALONG THE
NORTHWEST LOWER LAKE MICHIGAN COAST...ALTHOUGH DURATION DOES NOT
SUPPORT A SPECIFIC SCA HEADLINE. SOUTHWEST AND SUB-ADVISORY WINDS TO
CONTINUE THROUGH THURSDAY MORNING.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...SD
SYNOPSIS...SR
SHORT TERM...MB
LONG TERM...NS
AVIATION...SD
MARINE...MB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1123 AM CST WED FEB 13 2013
.AVIATION...18Z TAF. WEST TO NORTHWEST WINDS WILL INCREASE THIS
AFTERNOON AND CONTINUE THROUGH THE NIGHT. DURING THE MORNING ON
THURSDAY THE WINDS WILL INCREASE FURTHER. VFR CONDITIONS ARE
EXPECTED THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 453 AM CST WED FEB 13 2013/
SHORT TERM...THROUGH FRIDAY NIGHT. THE MAIN STORIES THROUGH THE
NEXT 72 HOURS INVOLVE A DOWNWARD TREND IN TEMPS AFTER A VERY MILD
ONE TODAY...STRONG NORTHWEST WINDS ON THURSDAY THAT MAY VERY WELL
REQUIRE A WIND ADVISORY ISSUANCE FOR AT LEAST PARTS OF THE
AREA...AND THE POSSIBILITY OF A FEW ROUNDS OF PASSING FLURRIES
DURING THE THURSDAY AFTERNOON THROUGH FRIDAY EVENING TIME FRAME
BUT WITH LITTLE...IF ANY RISK OF ACCUMULATING SNOW. IN
ADDITION...THE COMBINATION OF WARM AIR AND/OR GUSTY WINDS WILL
PROMOTE AT LEAST SOME ELEVATED...BUT LIKELY NON-CRITICAL...FIRE
DANGER IN PARTS OF THE AREA OVER THE NEXT FEW DAYS. THESE FIRE
WEATHER CONCERNS ARE FURTHER DISCUSSED IN THE SEPARATE SECTION
BELOW.
09Z CENTRAL PLAINS OBJECTIVE SURFACE ANALYSIS REVEALED A BROAD
AREA OF HIGH PRESSURE EXTENDING EASTWARD OUT OF THE ROCKIES...WITH
POSSIBLY A VERY SUBTLE TROUGH AXIS EXTENDING FROM FAR SOUTHEAST
NEB INTO SOUTHWEST KS. THIS REGIME WAS PROMOTING FAIRLY STEADY
5-10 MPH WESTERLY BREEZES ACROSS THE MAJORITY OF THE CWA...WHICH
ALONG WITH AN INCOMING BATCH OF HIGH LEVEL CLOUDS SHOULD KEEP MOST
AREAS UP INTO THE 21-25 DEGREE RANGE FOR MORNING LOW TEMPS.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA SHOWED THE
CENTRAL PLAINS UNDER NORTH-NORTHWEST FLOW ALOFT...IN BETWEEN THE
SOUTHERN STREAM SHORTWAVE TROUGH ALONG THE MO/AR BORDER...AND A
PARADE OF LOW AMPLITUDE DISTURBANCES ASSOCIATED WITH THE NORTHERN
STREAM JET IN THE SOUTHWEST CANADA/MONTANA AREA. 11-3.9 MICRON
SATELLITE IMAGERY REVEALS CLEAR SKIES OVER MOST OF THE CWA BUT AT
LEAST A THIN LAYER OF HIGH CLOUD WILL BE PASSING OVER MOST OF THE
AREA BETWEEN NOW AND SUNRISE.
TODAY WILL BE THE WELL-ANTICIPATED WARMEST DAY OF THE WEEK FOR THE
ENTIRE CWA. ALOFT...NORTHWEST FLOW WILL PERSIST...WITH ONLY THE
MOST SUBTLE OF MOISTURE-STARVED DISTURBANCES RIDING THROUGH THE
FLOW AS THE AREA REMAINS JUST SOUTH OF A SLIGHTLY STRONGER WAVE
CROSSING THE DAKOTAS THIS AFTERNOON. AS A RESULT...SKY COVER WILL
BE SOMEWHAT VARIABLE TODAY...GENERALLY AVERAGING PARTLY CLOUDY BUT
ALTERNATING BETWEEN PERIODS OF PLENTIFUL SUNSHINE AND PASSING
BATCHES OF MID-HIGH LEVEL CLOUDS. AT THE SURFACE...THE WEST-
NORTHWEST WIND REGIME WILL PERSIST...AND INCREASE IN SPEED IN
RESPONSE TO DEEPENING MIXING TO AT LEAST THE 850-800MB LAYER. AS A
RESULT...UPPED WIND SPEEDS A BIT FROM PREVIOUS FORECAST...AS THE
LATE MORNING-LATE AFTERNOON HOURS WILL FEATURE SUSTAINED SPEEDS AT
LEAST 15-20 MPH WITH SOME GUSTS 25+ MPH. THE DEEP MIXING WILL
COMBINE WITH SLIGHTLY WARMER AIR MOVING IN ALOFT FROM THE WEST TO
RESULT IN HIGH TEMPERATURES WELL INTO THE 50S NEARLY ALL AREAS.
NUDGED UP HIGH TEMPS 2-3 DEGREES FROM PREVIOUS GRIDS IN MOST
AREAS...GETTING MOST PLACES UP BETWEEN 52-55 DEGREES EXCEPT
SLIGHTLY COOLER UPPER 40S MAINLY IN PARTS OF VALLEY COUNTY WHERE
SOME SNOW PACK REMAINS. THESE FORECAST HIGHS ARE RIGHT IN LINE
WITH 07Z RAP HOURLY TEMPS...WHICH HAVE PERFORMED QUITE WELL THE
PAST TWO DAYS.
TONIGHT...HAVE HIGH CONFIDENCE THAT IT WILL REMAIN PRECIP-
FREE...BUT THE LEADING EDGES OF A COLD FRONT WILL START BLEEDING
DOWN FROM THE NORTH...IN RESPONSE TO A PARADE OF NORTHWEST-FLOW
CLIPPER WAVES ALOFT THAT WILL FOCUS ALONG AN AXIS FROM NORTH
DAKOTA-IOWA. SKY COVER WILL REMAIN VARIABLE THROUGH THE NIGHT...AS
STEADY WEST-NORTHWEST BREEZES REMAIN UP BETWEEN 10-20 MPH WITH
SOME HIGHER GUSTS. DESPITE THE WEAK COLD AIR ADVECTION...THESE
WINDS AND PASSING CLOUDS SHOULD HAVE NO PROBLEM KEEPING OVERNIGHT
LOW TEMPERATURES AT LEAST SLIGHTLY WARMER THAN THOSE THIS
MORNING...AND MADE LITTLE CHANGE KEEPING MOST AREAS UP BETWEEN
25-29 DEGREES...AND WOULD NOT BE SURPRISED TO SEE A BIT GREATER
COVERAGE OF LOWS RIGHT AROUND 30 THAN CURRENTLY DEPICTED.
THURSDAY IS UNDOUBTEDLY THE MOST ACTIVE OF THE SHORT TERM
PERIODS...MAINLY DUE TO STRONG WINDS. SINCE 24 HOURS AGO...MOST
MODELS/GUIDANCE HAVE CONTINUED TRENDING UPWARD A BIT WITH
NORTHWESTERLY SPEEDS. FOCUSING FIRST ALOFT...AS THE DAY WEARS ON A
SMALL BUT FAIRLY VIGOROUS MID LEVEL SHORTWAVE TROUGH WILL DROP
SOUTHWARD OUT OF THE DAKOTAS INTO NEB/IA. MEANWHILE AT THE
SURFACE...THE PRESSURE GRADIENT WILL RAMP UP IN RESPONSE TO
INCREASING HIGH PRESSURE EMANATING FROM AN EXPANSIVE NORTHERN
ROCKIES RIDGE. ONCE DIURNAL MIXING KICKS IN AND LOW LEVEL LAPSE
RATES STEEPEN...THE 06Z NAM ADVERTISES MIXING TO DEEPEN WELL UP
INTO THE 800MB TO POSSIBLY 700MB RANGE...WITH AVERAGING WIND
SPEEDS THROUGH THIS MIXED LAYER EASILY SUPPORTING AT LEAST LOW-END
ADVISORY SUSTAINED SPEEDS BETWEEN 30-35 MPH AND GUSTS TO AROUND 45
MPH. WILL ADD THIS STRONG WIND MENTION TO THE HAZARDOUS WEATHER
OUTLOOK...BUT GIVEN IT IS STILL 3 PERIODS AWAY WILL HOLD OFF ON A
WIND ADVISORY FOR NOW...AND GIVE DAY SHIFT ANOTHER LOOK TO
DETERMINE WHETHER AN ADVISORY MAY BE JUSTIFIED FOR ALL 30
COUNTIES...OR MAINLY FOR THE NORTHERN 1/2 OF THE CWA WHICH LOOKS
SLIGHTLY MORE FAVORABLE TO MEET 30+ MPH FOR SEVERAL HOURS VERSUS
SOUTHERN ZONES. THE MAIN WINDOW FOR THE STRONGEST WINDS GENERALLY
LOOKS TO TARGET THE 11 AM-6 PM TIME FRAME. AS FOR PRECIP
CHANCES...HAVE NOTHING MENTIONED DURING THE MORNING...BUT HAVE RE-
INTRODUCED SOME FLURRY CHANCES FOR SOME AREAS NORTH OF I-80 DURING
THE AFTERNOON AS LOW LEVEL STRATUS SWEEPS IN FROM THE NORTH. NOT
THINKING ANYTHING ACCUMULATING AT THIS POINT...WITH BETTER CHANCES
FOR A LIGHT DUSTING FOCUSING JUST NORTH OF OUR AREA. TEMP-
WISE...IF IT WASN/T FOR THE WIND IT REALLY WOULDN/T FEEL TOO
BAD...AND ONLY MADE MINOR TWEAKS TO HIGHS RANGING FROM UPPER 30S
FAR NORTH...LOW 40S CENTRAL AND MID 40S IN KS ZONES.
TAKING A BIT BROADER LOOK AT THE THURSDAY NIGHT THROUGH FRIDAY
NIGHT TIME FRAME...THE BIG PICTURE ALOFT INVOLVES THE CENTRAL
PLAINS REMAINING UNDER NORTHWEST FLOW ALOFT AS A CONTINUING PARADE
OF MID LEVEL SHORTWAVE TROUGHS ROTATING SOUTH-SOUTHEAST OUT OF
CANADA WILL CARVE OUT AN EXPANSIVE LONGWAVE TROUGH THAT WILL
DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. ON THURSDAY
NIGHT...THE INITIAL SHORTWAVE TROUGH WILL PASS JUST SOUTHEAST OF
OUR AREA...WHILE UPSTREAM THE NEXT MAIN ONE ENTERS THE DAKOTAS.
WIND SPEEDS WILL EASE DOWN QUITE A BIT...ESPECIALLY POST-MIDNIGHT
WHEN SPEEDS DECREASE INTO THE 5-10 MPH RANGE. ALTHOUGH SOME AREAS
MAY NOT SEE A SINGLE SNOWFLAKE...OPTED TO KEEP THE GRIDS AS SIMPLE
AS POSSIBLE AND BLANKET THE ENTIRE CWA WITH A SLIGHT CHANCE OF
FLURRIES ALL THE WAY FROM THURSDAY NIGHT THROUGH FRIDAY EVENING
AS THIS PATTERN OFTEN EVOKES SMALL-SCALE PATCHES OR BANDS OF NON-
MEASURABLE SNOW UNDERNEATH THE UPPER JET EXIT REGION...ESPECIALLY
IF SOME OF THE PASSING LOWER STRATUS HAS FAVORABLE DENDRITIC
TEMPERATURES. ALTHOUGH SUPPOSE A SMALL PERCENTAGE OF THE CWA COULD
SEE A LIGHT MEASURABLE DUSTING...ITS TOO EARLY TO DETERMINE WHERE
THIS MIGHT EVEN BE...SO CANNOT JUSTIFY A MEASURABLE 20+ POP
ANYWHERE AT THIS TIME FRAME. WINDS ON FRIDAY WILL REMAIN FROM THE
NORTH-NORTHWEST BUT DO NOT APPEAR NEARLY AS STRONG AS THURSDAY WITH
SUSTAINED SPEEDS GENERALLY TOPPING OUT AROUND 15 MPH. AS FOR
TEMPS...MADE ONLY A SMALL DOWNWARD NUDGE TO THURSDAY NIGHT WITH
MOST AREAS 16-20 DEGREES. FRIDAY STILL SHOULD BE THE COLDEST DAY
OF THE WEEK...BUT ACTUALLY NUDGED UP VALUES A BIT IN SOME AREAS
DUE TO DECENT MIXING POTENTIAL...RANGING FROM MID 30S IN MOST NEB
ZONES TO NEAR 40 IN KS. BY MIDNIGHT FRIDAY NIGHT...ANY FLURRY RISK
SHOULD BE OVER WITH AS THE BACK EDGE OF THE LAST IN A SERIES OF
MID LEVEL SHORTWAVE TROUGHS EXITS THE AREA.
LONG TERM...SATURDAY THROUGH TUESDAY. DRY CONDITIONS ARE FORECAST
THROUGH THE EXTENDED PERIODS. ON SATURDAY...THE PATTERN ALOFT WILL
FEATURE A TROUGH MOVING INTO THE PACIFIC NORTHWEST...RIDGING OVER
THE ROCKIES AND A LONGWAVE TROUGH FROM THE HUDSON BAY SOUTH TO THE
GULF COAST STATES. HEIGHTS WILL RISE ACROSS THE CENTRAL PLAINS OVER
THE WEEKEND AS THE WESTERN RIDGE BUILDS ONTO PLAINS AND THE COLD
AIRMASS ASSOCIATED WITH THE TROUGH TO THE EAST DEPARTS. THE RIDGE
BEGINS TO BREAK DOWN SUNDAY AS AN UPSTREAM TROUGH REACHES THE NORTH
CENTRAL ROCKIES. THIS NEXT TROUGH AND ASSOCIATED COLD FRONT CROSSES
THE CENTRAL PLAINS SUNDAY NIGHT/MONDAY...BRINGING ANOTHER ROUND OF
COLD AIR TO START THE WORKWEEK. TEMPERATURE WISE...TEMPS BEGIN TO
RECOVER ON SATURDAY BEHIND THE UPPER TROUGH...THEN SUNDAY WILL BE
THE WARMEST OF THE EXTENDED PERIODS WITH THE MILD AIRMASS IN PLACE
AHEAD OF THE NEXT APPROACHING COLD FRONT/SYSTEM. HIGHS SUNDAY ARE
LOOKING WELL ABOVE NORMAL IN THE 50S...THEN FOLLOWING COLD FROPA
TEMPS RETURN CLOSER TO FEBRUARY NORMALS FOR MON/TUES.
FIRE WEATHER...ALTHOUGH OUTRIGHT CRITICAL FIRE WEATHER
THRESHOLDS ARE CURRENTLY NOT FORECAST DURING THE NEXT FEW
DAYS...AT LEAST PARTS OF THE CWA BEAR WATCHING FOR SOME ELEVATED
TO NEAR-CRITICAL COMBINATIONS OF WIND AND RELATIVE HUMIDITY.
STARTING OFF TODAY...WEST-NORTHWEST SUSTAINED WIND SPEEDS WILL
AVERAGE 15-20 MPH IN NEARLY ALL AREAS...WITH SPORADIC TO FREQUENT
GUSTS TO 25+ MPH EXPECTED. FORTUNATELY...AFTERNOON RELATIVE
HUMIDITY VALUES ACROSS MOST OF THE ARE FORECAST TO HOLD SLIGHTLY
ABOVE CRITICAL LEVELS IN THE 25-30 PERCENT RANGE. HOWEVER...IT
COULD BE A CLOSE CALL ESPECIALLY IN PARTS OF PHILLIPS/ROOKS/OSBORNE
COUNTIES IN KANSAS...WHERE RH VALUES COULD EDGE A BIT CLOSER TO 20
PERCENT. WILL INTRODUCE AN ELEVATED FIRE DANGER MENTION INTO THE
HAZARDOUS WEATHER OUTLOOK MAINLY FOR THIS AREA. TURNING TO
THURSDAY...AS OUTLINED ABOVE STRONG SUSTAINED WINDS AROUND 30 MPH
OR HIGHER ARE FORECAST ACROSS NEARLY THE ENTIRE CWA.
FORTUNATELY...COOLER TEMPERATURES WILL KEEP AFTERNOON RH
PERCENTAGES ABOVE 30 PERCENT ACROSS NEBRASKA ZONES...BUT KS ZONES
COULD SEE VALUES CREEP DOWN CLOSER TO 25 PERCENT. BOTTOM LINE
IS...WHILE NO MAJOR FIRE DANGER ISSUES ARE ANTICIPATED THESE NEXT
FEW DAYS...SOME CAUTION MAY NEED TAKEN...AND HOURLY RELATIVE
HUMIDITY TRENDS THESE NEXT FEW AFTERNOONS WILL NEED WATCHED
CLOSELY TO MAKE SURE THERE ARE NO SURPRISES DROPPING BELOW 20
PERCENT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
508 AM CST WED FEB 13 2013
.AVIATION...12Z TAF. CONDITIONS WILL REMAIN AT VFR THROUGH THE
TAF PERIOD. WEST WINDS WILL INCREASE THIS AFTN AHEAD OF AN
APPROACHING FRONTAL BOUNDARY WITH GUSTS OVER 20KTS POSSIBLE. A
COLD FRONTAL BOUNDARY WILL CROSS THE TERMINAL TONIGHT...WITH WINDS
SWITCHING NORTHWESTERLY AND INCREASING...SETTING THE STAGE FOR A WINDY
DAY ON THURSDAY...JUST BEYOND THE TAF PERIOD. PERIODS OF MID/HIGH
CLOUDS WILL CROSS GRI WITH AN OCCASIONAL VFR CEILING.
&&
.PREV DISCUSSION... /ISSUED 453 AM CST WED FEB 13 2013/
SHORT TERM...THROUGH FRIDAY NIGHT. THE MAIN STORIES THROUGH THE
NEXT 72 HOURS INVOLVE A DOWNWARD TREND IN TEMPS AFTER A VERY MILD
ONE TODAY...STRONG NORTHWEST WINDS ON THURSDAY THAT MAY VERY WELL
REQUIRE A WIND ADVISORY ISSUANCE FOR AT LEAST PARTS OF THE
AREA...AND THE POSSIBILITY OF A FEW ROUNDS OF PASSING FLURRIES
DURING THE THURSDAY AFTERNOON THROUGH FRIDAY EVENING TIME FRAME
BUT WITH LITTLE...IF ANY RISK OF ACCUMULATING SNOW. IN
ADDITION...THE COMBINATION OF WARM AIR AND/OR GUSTY WINDS WILL
PROMOTE AT LEAST SOME ELEVATED...BUT LIKELY NON-CRITICAL...FIRE
DANGER IN PARTS OF THE AREA OVER THE NEXT FEW DAYS. THESE FIRE
WEATHER CONCERNS ARE FURTHER DISCUSSED IN THE SEPARATE SECTION
BELOW.
09Z CENTRAL PLAINS OBJECTIVE SURFACE ANALYSIS REVEALED A BROAD
AREA OF HIGH PRESSURE EXTENDING EASTWARD OUT OF THE ROCKIES...WITH
POSSIBLY A VERY SUBTLE TROUGH AXIS EXTENDING FROM FAR SOUTHEAST
NEB INTO SOUTHWEST KS. THIS REGIME WAS PROMOTING FAIRLY STEADY
5-10 MPH WESTERLY BREEZES ACROSS THE MAJORITY OF THE CWA...WHICH
ALONG WITH AN INCOMING BATCH OF HIGH LEVEL CLOUDS SHOULD KEEP MOST
AREAS UP INTO THE 21-25 DEGREE RANGE FOR MORNING LOW TEMPS.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA SHOWED THE
CENTRAL PLAINS UNDER NORTH-NORTHWEST FLOW ALOFT...IN BETWEEN THE
SOUTHERN STREAM SHORTWAVE TROUGH ALONG THE MO/AR BORDER...AND A
PARADE OF LOW AMPLITUDE DISTURBANCES ASSOCIATED WITH THE NORTHERN
STREAM JET IN THE SOUTHWEST CANADA/MONTANA AREA. 11-3.9 MICRON
SATELLITE IMAGERY REVEALS CLEAR SKIES OVER MOST OF THE CWA BUT AT
LEAST A THIN LAYER OF HIGH CLOUD WILL BE PASSING OVER MOST OF THE
AREA BETWEEN NOW AND SUNRISE.
TODAY WILL BE THE WELL-ANTICIPATED WARMEST DAY OF THE WEEK FOR THE
ENTIRE CWA. ALOFT...NORTHWEST FLOW WILL PERSIST...WITH ONLY THE
MOST SUBTLE OF MOISTURE-STARVED DISTURBANCES RIDING THROUGH THE
FLOW AS THE AREA REMAINS JUST SOUTH OF A SLIGHTLY STRONGER WAVE
CROSSING THE DAKOTAS THIS AFTERNOON. AS A RESULT...SKY COVER WILL
BE SOMEWHAT VARIABLE TODAY...GENERALLY AVERAGING PARTLY CLOUDY BUT
ALTERNATING BETWEEN PERIODS OF PLENTIFUL SUNSHINE AND PASSING
BATCHES OF MID-HIGH LEVEL CLOUDS. AT THE SURFACE...THE WEST-
NORTHWEST WIND REGIME WILL PERSIST...AND INCREASE IN SPEED IN
RESPONSE TO DEEPENING MIXING TO AT LEAST THE 850-800MB LAYER. AS A
RESULT...UPPED WIND SPEEDS A BIT FROM PREVIOUS FORECAST...AS THE
LATE MORNING-LATE AFTERNOON HOURS WILL FEATURE SUSTAINED SPEEDS AT
LEAST 15-20 MPH WITH SOME GUSTS 25+ MPH. THE DEEP MIXING WILL
COMBINE WITH SLIGHTLY WARMER AIR MOVING IN ALOFT FROM THE WEST TO
RESULT IN HIGH TEMPERATURES WELL INTO THE 50S NEARLY ALL AREAS.
NUDGED UP HIGH TEMPS 2-3 DEGREES FROM PREVIOUS GRIDS IN MOST
AREAS...GETTING MOST PLACES UP BETWEEN 52-55 DEGREES EXCEPT
SLIGHTLY COOLER UPPER 40S MAINLY IN PARTS OF VALLEY COUNTY WHERE
SOME SNOW PACK REMAINS. THESE FORECAST HIGHS ARE RIGHT IN LINE
WITH 07Z RAP HOURLY TEMPS...WHICH HAVE PERFORMED QUITE WELL THE
PAST TWO DAYS.
TONIGHT...HAVE HIGH CONFIDENCE THAT IT WILL REMAIN PRECIP-
FREE...BUT THE LEADING EDGES OF A COLD FRONT WILL START BLEEDING
DOWN FROM THE NORTH...IN RESPONSE TO A PARADE OF NORTHWEST-FLOW
CLIPPER WAVES ALOFT THAT WILL FOCUS ALONG AN AXIS FROM NORTH
DAKOTA-IOWA. SKY COVER WILL REMAIN VARIABLE THROUGH THE NIGHT...AS
STEADY WEST-NORTHWEST BREEZES REMAIN UP BETWEEN 10-20 MPH WITH
SOME HIGHER GUSTS. DESPITE THE WEAK COLD AIR ADVECTION...THESE
WINDS AND PASSING CLOUDS SHOULD HAVE NO PROBLEM KEEPING OVERNIGHT
LOW TEMPERATURES AT LEAST SLIGHTLY WARMER THAN THOSE THIS
MORNING...AND MADE LITTLE CHANGE KEEPING MOST AREAS UP BETWEEN
25-29 DEGREES...AND WOULD NOT BE SURPRISED TO SEE A BIT GREATER
COVERAGE OF LOWS RIGHT AROUND 30 THAN CURRENTLY DEPICTED.
THURSDAY IS UNDOUBTEDLY THE MOST ACTIVE OF THE SHORT TERM
PERIODS...MAINLY DUE TO STRONG WINDS. SINCE 24 HOURS AGO...MOST
MODELS/GUIDANCE HAVE CONTINUED TRENDING UPWARD A BIT WITH
NORTHWESTERLY SPEEDS. FOCUSING FIRST ALOFT...AS THE DAY WEARS ON A
SMALL BUT FAIRLY VIGOROUS MID LEVEL SHORTWAVE TROUGH WILL DROP
SOUTHWARD OUT OF THE DAKOTAS INTO NEB/IA. MEANWHILE AT THE
SURFACE...THE PRESSURE GRADIENT WILL RAMP UP IN RESPONSE TO
INCREASING HIGH PRESSURE EMANATING FROM AN EXPANSIVE NORTHERN
ROCKIES RIDGE. ONCE DIURNAL MIXING KICKS IN AND LOW LEVEL LAPSE
RATES STEEPEN...THE 06Z NAM ADVERTISES MIXING TO DEEPEN WELL UP
INTO THE 800MB TO POSSIBLY 700MB RANGE...WITH AVERAGING WIND
SPEEDS THROUGH THIS MIXED LAYER EASILY SUPPORTING AT LEAST LOW-END
ADVISORY SUSTAINED SPEEDS BETWEEN 30-35 MPH AND GUSTS TO AROUND 45
MPH. WILL ADD THIS STRONG WIND MENTION TO THE HAZARDOUS WEATHER
OUTLOOK...BUT GIVEN IT IS STILL 3 PERIODS AWAY WILL HOLD OFF ON A
WIND ADVISORY FOR NOW...AND GIVE DAY SHIFT ANOTHER LOOK TO
DETERMINE WHETHER AN ADVISORY MAY BE JUSTIFIED FOR ALL 30
COUNTIES...OR MAINLY FOR THE NORTHERN 1/2 OF THE CWA WHICH LOOKS
SLIGHTLY MORE FAVORABLE TO MEET 30+ MPH FOR SEVERAL HOURS VERSUS
SOUTHERN ZONES. THE MAIN WINDOW FOR THE STRONGEST WINDS GENERALLY
LOOKS TO TARGET THE 11 AM-6 PM TIME FRAME. AS FOR PRECIP
CHANCES...HAVE NOTHING MENTIONED DURING THE MORNING...BUT HAVE RE-
INTRODUCED SOME FLURRY CHANCES FOR SOME AREAS NORTH OF I-80 DURING
THE AFTERNOON AS LOW LEVEL STRATUS SWEEPS IN FROM THE NORTH. NOT
THINKING ANYTHING ACCUMULATING AT THIS POINT...WITH BETTER CHANCES
FOR A LIGHT DUSTING FOCUSING JUST NORTH OF OUR AREA. TEMP-
WISE...IF IT WASN/T FOR THE WIND IT REALLY WOULDN/T FEEL TOO
BAD...AND ONLY MADE MINOR TWEAKS TO HIGHS RANGING FROM UPPER 30S
FAR NORTH...LOW 40S CENTRAL AND MID 40S IN KS ZONES.
TAKING A BIT BROADER LOOK AT THE THURSDAY NIGHT THROUGH FRIDAY
NIGHT TIME FRAME...THE BIG PICTURE ALOFT INVOLVES THE CENTRAL
PLAINS REMAINING UNDER NORTHWEST FLOW ALOFT AS A CONTINUING PARADE
OF MID LEVEL SHORTWAVE TROUGHS ROTATING SOUTH-SOUTHEAST OUT OF
CANADA WILL CARVE OUT AN EXPANSIVE LONGWAVE TROUGH THAT WILL
DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. ON THURSDAY
NIGHT...THE INITIAL SHORTWAVE TROUGH WILL PASS JUST SOUTHEAST OF
OUR AREA...WHILE UPSTREAM THE NEXT MAIN ONE ENTERS THE DAKOTAS.
WIND SPEEDS WILL EASE DOWN QUITE A BIT...ESPECIALLY POST-MIDNIGHT
WHEN SPEEDS DECREASE INTO THE 5-10 MPH RANGE. ALTHOUGH SOME AREAS
MAY NOT SEE A SINGLE SNOWFLAKE...OPTED TO KEEP THE GRIDS AS SIMPLE
AS POSSIBLE AND BLANKET THE ENTIRE CWA WITH A SLIGHT CHANCE OF
FLURRIES ALL THE WAY FROM THURSDAY NIGHT THROUGH FRIDAY EVENING
AS THIS PATTERN OFTEN EVOKES SMALL-SCALE PATCHES OR BANDS OF NON-
MEASURABLE SNOW UNDERNEATH THE UPPER JET EXIT REGION...ESPECIALLY
IF SOME OF THE PASSING LOWER STRATUS HAS FAVORABLE DENDRITIC
TEMPERATURES. ALTHOUGH SUPPOSE A SMALL PERCENTAGE OF THE CWA COULD
SEE A LIGHT MEASURABLE DUSTING...ITS TOO EARLY TO DETERMINE WHERE
THIS MIGHT EVEN BE...SO CANNOT JUSTIFY A MEASURABLE 20+ POP
ANYWHERE AT THIS TIME FRAME. WINDS ON FRIDAY WILL REMAIN FROM THE
NORTH-NORTHWEST BUT DO NOT APPEAR NEARLY AS STRONG AS THURSDAY WITH
SUSTAINED SPEEDS GENERALLY TOPPING OUT AROUND 15 MPH. AS FOR
TEMPS...MADE ONLY A SMALL DOWNWARD NUDGE TO THURSDAY NIGHT WITH
MOST AREAS 16-20 DEGREES. FRIDAY STILL SHOULD BE THE COLDEST DAY
OF THE WEEK...BUT ACTUALLY NUDGED UP VALUES A BIT IN SOME AREAS
DUE TO DECENT MIXING POTENTIAL...RANGING FROM MID 30S IN MOST NEB
ZONES TO NEAR 40 IN KS. BY MIDNIGHT FRIDAY NIGHT...ANY FLURRY RISK
SHOULD BE OVER WITH AS THE BACK EDGE OF THE LAST IN A SERIES OF
MID LEVEL SHORTWAVE TROUGHS EXITS THE AREA.
LONG TERM...SATURDAY THROUGH TUESDAY. DRY CONDITIONS ARE FORECAST
THROUGH THE EXTENDED PERIODS. ON SATURDAY...THE PATTERN ALOFT WILL
FEATURE A TROUGH MOVING INTO THE PACIFIC NORTHWEST...RIDGING OVER
THE ROCKIES AND A LONGWAVE TROUGH FROM THE HUDSON BAY SOUTH TO THE
GULF COAST STATES. HEIGHTS WILL RISE ACROSS THE CENTRAL PLAINS OVER
THE WEEKEND AS THE WESTERN RIDGE BUILDS ONTO PLAINS AND THE COLD
AIRMASS ASSOCIATED WITH THE TROUGH TO THE EAST DEPARTS. THE RIDGE
BEGINS TO BREAK DOWN SUNDAY AS AN UPSTREAM TROUGH REACHES THE NORTH
CENTRAL ROCKIES. THIS NEXT TROUGH AND ASSOCIATED COLD FRONT CROSSES
THE CENTRAL PLAINS SUNDAY NIGHT/MONDAY...BRINGING ANOTHER ROUND OF
COLD AIR TO START THE WORKWEEK. TEMPERATURE WISE...TEMPS BEGIN TO
RECOVER ON SATURDAY BEHIND THE UPPER TROUGH...THEN SUNDAY WILL BE
THE WARMEST OF THE EXTENDED PERIODS WITH THE MILD AIRMASS IN PLACE
AHEAD OF THE NEXT APPROACHING COLD FRONT/SYSTEM. HIGHS SUNDAY ARE
LOOKING WELL ABOVE NORMAL IN THE 50S...THEN FOLLOWING COLD FROPA
TEMPS RETURN CLOSER TO FEBRUARY NORMALS FOR MON/TUES.
FIRE WEATHER...ALTHOUGH OUTRIGHT CRITICAL FIRE WEATHER
THRESHOLDS ARE CURRENTLY NOT FORECAST DURING THE NEXT FEW
DAYS...AT LEAST PARTS OF THE CWA BEAR WATCHING FOR SOME ELEVATED
TO NEAR-CRITICAL COMBINATIONS OF WIND AND RELATIVE HUMIDITY.
STARTING OFF TODAY...WEST-NORTHWEST SUSTAINED WIND SPEEDS WILL
AVERAGE 15-20 MPH IN NEARLY ALL AREAS...WITH SPORADIC TO FREQUENT
GUSTS TO 25+ MPH EXPECTED. FORTUNATELY...AFTERNOON RELATIVE
HUMIDITY VALUES ACROSS MOST OF THE ARE FORECAST TO HOLD SLIGHTLY
ABOVE CRITICAL LEVELS IN THE 25-30 PERCENT RANGE. HOWEVER...IT
COULD BE A CLOSE CALL ESPECIALLY IN PARTS OF PHILLIPS/ROOKS/OSBORNE
COUNTIES IN KANSAS...WHERE RH VALUES COULD EDGE A BIT CLOSER TO 20
PERCENT. WILL INTRODUCE AN ELEVATED FIRE DANGER MENTION INTO THE
HAZARDOUS WEATHER OUTLOOK MAINLY FOR THIS AREA. TURNING TO
THURSDAY...AS OUTLINED ABOVE STRONG SUSTAINED WINDS AROUND 30 MPH
OR HIGHER ARE FORECAST ACROSS NEARLY THE ENTIRE CWA.
FORTUNATELY...COOLER TEMPERATURES WILL KEEP AFTERNOON RH
PERCENTAGES ABOVE 30 PERCENT ACROSS NEBRASKA ZONES...BUT KS ZONES
COULD SEE VALUES CREEP DOWN CLOSER TO 25 PERCENT. BOTTOM LINE
IS...WHILE NO MAJOR FIRE DANGER ISSUES ARE ANTICIPATED THESE NEXT
FEW DAYS...SOME CAUTION MAY NEED TAKEN...AND HOURLY RELATIVE
HUMIDITY TRENDS THESE NEXT FEW AFTERNOONS WILL NEED WATCHED
CLOSELY TO MAKE SURE THERE ARE NO SURPRISES DROPPING BELOW 20
PERCENT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...PFANNKUCH
LONG TERM/AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
453 AM CST WED FEB 13 2013
.SHORT TERM...THROUGH FRIDAY NIGHT. THE MAIN STORIES THROUGH THE
NEXT 72 HOURS INVOLVE A DOWNWARD TREND IN TEMPS AFTER A VERY MILD
ONE TODAY...STRONG NORTHWEST WINDS ON THURSDAY THAT MAY VERY WELL
REQUIRE A WIND ADVISORY ISSUANCE FOR AT LEAST PARTS OF THE
AREA...AND THE POSSIBILITY OF A FEW ROUNDS OF PASSING FLURRIES
DURING THE THURSDAY AFTERNOON THROUGH FRIDAY EVENING TIME FRAME
BUT WITH LITTLE...IF ANY RISK OF ACCUMULATING SNOW. IN
ADDITION...THE COMBINATION OF WARM AIR AND/OR GUSTY WINDS WILL
PROMOTE AT LEAST SOME ELEVATED...BUT LIKELY NON-CRITICAL...FIRE
DANGER IN PARTS OF THE AREA OVER THE NEXT FEW DAYS. THESE FIRE
WEATHER CONCERNS ARE FURTHER DISCUSSED IN THE SEPARATE SECTION
BELOW.
09Z CENTRAL PLAINS OBJECTIVE SURFACE ANALYSIS REVEALED A BROAD
AREA OF HIGH PRESSURE EXTENDING EASTWARD OUT OF THE ROCKIES...WITH
POSSIBLY A VERY SUBTLE TROUGH AXIS EXTENDING FROM FAR SOUTHEAST
NEB INTO SOUTHWEST KS. THIS REGIME WAS PROMOTING FAIRLY STEADY
5-10 MPH WESTERLY BREEZES ACROSS THE MAJORITY OF THE CWA...WHICH
ALONG WITH AN INCOMING BATCH OF HIGH LEVEL CLOUDS SHOULD KEEP MOST
AREAS UP INTO THE 21-25 DEGREE RANGE FOR MORNING LOW TEMPS.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA SHOWED THE
CENTRAL PLAINS UNDER NORTH-NORTHWEST FLOW ALOFT...IN BETWEEN THE
SOUTHERN STREAM SHORTWAVE TROUGH ALONG THE MO/AR BORDER...AND A
PARADE OF LOW AMPLITUDE DISTURBANCES ASSOCIATED WITH THE NORTHERN
STREAM JET IN THE SOUTHWEST CANADA/MONTANA AREA. 11-3.9 MICRON
SATELLITE IMAGERY REVEALS CLEAR SKIES OVER MOST OF THE CWA BUT AT
LEAST A THIN LAYER OF HIGH CLOUD WILL BE PASSING OVER MOST OF THE
AREA BETWEEN NOW AND SUNRISE.
TODAY WILL BE THE WELL-ANTICIPATED WARMEST DAY OF THE WEEK FOR THE
ENTIRE CWA. ALOFT...NORTHWEST FLOW WILL PERSIST...WITH ONLY THE
MOST SUBTLE OF MOISTURE-STARVED DISTURBANCES RIDING THROUGH THE
FLOW AS THE AREA REMAINS JUST SOUTH OF A SLIGHTLY STRONGER WAVE
CROSSING THE DAKOTAS THIS AFTERNOON. AS A RESULT...SKY COVER WILL
BE SOMEWHAT VARIABLE TODAY...GENERALLY AVERAGING PARTLY CLOUDY BUT
ALTERNATING BETWEEN PERIODS OF PLENTIFUL SUNSHINE AND PASSING
BATCHES OF MID-HIGH LEVEL CLOUDS. AT THE SURFACE...THE WEST-
NORTHWEST WIND REGIME WILL PERSIST...AND INCREASE IN SPEED IN
RESPONSE TO DEEPENING MIXING TO AT LEAST THE 850-800MB LAYER. AS A
RESULT...UPPED WIND SPEEDS A BIT FROM PREVIOUS FORECAST...AS THE
LATE MORNING-LATE AFTERNOON HOURS WILL FEATURE SUSTAINED SPEEDS AT
LEAST 15-20 MPH WITH SOME GUSTS 25+ MPH. THE DEEP MIXING WILL
COMBINE WITH SLIGHTLY WARMER AIR MOVING IN ALOFT FROM THE WEST TO
RESULT IN HIGH TEMPERATURES WELL INTO THE 50S NEARLY ALL AREAS.
NUDGED UP HIGH TEMPS 2-3 DEGREES FROM PREVIOUS GRIDS IN MOST
AREAS...GETTING MOST PLACES UP BETWEEN 52-55 DEGREES EXCEPT
SLIGHTLY COOLER UPPER 40S MAINLY IN PARTS OF VALLEY COUNTY WHERE
SOME SNOW PACK REMAINS. THESE FORECAST HIGHS ARE RIGHT IN LINE
WITH 07Z RAP HOURLY TEMPS...WHICH HAVE PERFORMED QUITE WELL THE
PAST TWO DAYS.
TONIGHT...HAVE HIGH CONFIDENCE THAT IT WILL REMAIN PRECIP-
FREE...BUT THE LEADING EDGES OF A COLD FRONT WILL START BLEEDING
DOWN FROM THE NORTH...IN RESPONSE TO A PARADE OF NORTHWEST-FLOW
CLIPPER WAVES ALOFT THAT WILL FOCUS ALONG AN AXIS FROM NORTH
DAKOTA-IOWA. SKY COVER WILL REMAIN VARIABLE THROUGH THE NIGHT...AS
STEADY WEST-NORTHWEST BREEZES REMAIN UP BETWEEN 10-20 MPH WITH
SOME HIGHER GUSTS. DESPITE THE WEAK COLD AIR ADVECTION...THESE
WINDS AND PASSING CLOUDS SHOULD HAVE NO PROBLEM KEEPING OVERNIGHT
LOW TEMPERATURES AT LEAST SLIGHTLY WARMER THAN THOSE THIS
MORNING...AND MADE LITTLE CHANGE KEEPING MOST AREAS UP BETWEEN
25-29 DEGREES...AND WOULD NOT BE SURPRISED TO SEE A BIT GREATER
COVERAGE OF LOWS RIGHT AROUND 30 THAN CURRENTLY DEPICTED.
THURSDAY IS UNDOUBTEDLY THE MOST ACTIVE OF THE SHORT TERM
PERIODS...MAINLY DUE TO STRONG WINDS. SINCE 24 HOURS AGO...MOST
MODELS/GUIDANCE HAVE CONTINUED TRENDING UPWARD A BIT WITH
NORTHWESTERLY SPEEDS. FOCUSING FIRST ALOFT...AS THE DAY WEARS ON A
SMALL BUT FAIRLY VIGOROUS MID LEVEL SHORTWAVE TROUGH WILL DROP
SOUTHWARD OUT OF THE DAKOTAS INTO NEB/IA. MEANWHILE AT THE
SURFACE...THE PRESSURE GRADIENT WILL RAMP UP IN RESPONSE TO
INCREASING HIGH PRESSURE EMANATING FROM AN EXPANSIVE NORTHERN
ROCKIES RIDGE. ONCE DIURNAL MIXING KICKS IN AND LOW LEVEL LAPSE
RATES STEEPEN...THE 06Z NAM ADVERTISES MIXING TO DEEPEN WELL UP
INTO THE 800MB TO POSSIBLY 700MB RANGE...WITH AVERAGING WIND
SPEEDS THROUGH THIS MIXED LAYER EASILY SUPPORTING AT LEAST LOW-END
ADVISORY SUSTAINED SPEEDS BETWEEN 30-35 MPH AND GUSTS TO AROUND 45
MPH. WILL ADD THIS STRONG WIND MENTION TO THE HAZARDOUS WEATHER
OUTLOOK...BUT GIVEN IT IS STILL 3 PERIODS AWAY WILL HOLD OFF ON A
WIND ADVISORY FOR NOW...AND GIVE DAY SHIFT ANOTHER LOOK TO
DETERMINE WHETHER AN ADVISORY MAY BE JUSTIFIED FOR ALL 30
COUNTIES...OR MAINLY FOR THE NORTHERN 1/2 OF THE CWA WHICH LOOKS
SLIGHTLY MORE FAVORABLE TO MEET 30+ MPH FOR SEVERAL HOURS VERSUS
SOUTHERN ZONES. THE MAIN WINDOW FOR THE STRONGEST WINDS GENERALLY
LOOKS TO TARGET THE 11 AM-6 PM TIME FRAME. AS FOR PRECIP
CHANCES...HAVE NOTHING MENTIONED DURING THE MORNING...BUT HAVE RE-
INTRODUCED SOME FLURRY CHANCES FOR SOME AREAS NORTH OF I-80 DURING
THE AFTERNOON AS LOW LEVEL STRATUS SWEEPS IN FROM THE NORTH. NOT
THINKING ANYTHING ACCUMULATING AT THIS POINT...WITH BETTER CHANCES
FOR A LIGHT DUSTING FOCUSING JUST NORTH OF OUR AREA. TEMP-
WISE...IF IT WASN/T FOR THE WIND IT REALLY WOULDN/T FEEL TOO
BAD...AND ONLY MADE MINOR TWEAKS TO HIGHS RANGING FROM UPPER 30S
FAR NORTH...LOW 40S CENTRAL AND MID 40S IN KS ZONES.
TAKING A BIT BROADER LOOK AT THE THURSDAY NIGHT THROUGH FRIDAY
NIGHT TIME FRAME...THE BIG PICTURE ALOFT INVOLVES THE CENTRAL
PLAINS REMAINING UNDER NORTHWEST FLOW ALOFT AS A CONTINUING PARADE
OF MID LEVEL SHORTWAVE TROUGHS ROTATING SOUTH-SOUTHEAST OUT OF
CANADA WILL CARVE OUT AN EXPANSIVE LONGWAVE TROUGH THAT WILL
DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. ON THURSDAY
NIGHT...THE INITIAL SHORTWAVE TROUGH WILL PASS JUST SOUTHEAST OF
OUR AREA...WHILE UPSTREAM THE NEXT MAIN ONE ENTERS THE DAKOTAS.
WIND SPEEDS WILL EASE DOWN QUITE A BIT...ESPECIALLY POST-MIDNIGHT
WHEN SPEEDS DECREASE INTO THE 5-10 MPH RANGE. ALTHOUGH SOME AREAS
MAY NOT SEE A SINGLE SNOWFLAKE...OPTED TO KEEP THE GRIDS AS SIMPLE
AS POSSIBLE AND BLANKET THE ENTIRE CWA WITH A SLIGHT CHANCE OF
FLURRIES ALL THE WAY FROM THURSDAY NIGHT THROUGH FRIDAY EVENING
AS THIS PATTERN OFTEN EVOKES SMALL-SCALE PATCHES OR BANDS OF NON-
MEASURABLE SNOW UNDERNEATH THE UPPER JET EXIT REGION...ESPECIALLY
IF SOME OF THE PASSING LOWER STRATUS HAS FAVORABLE DENDRITIC
TEMPERATURES. ALTHOUGH SUPPOSE A SMALL PERCENTAGE OF THE CWA COULD
SEE A LIGHT MEASURABLE DUSTING...ITS TOO EARLY TO DETERMINE WHERE
THIS MIGHT EVEN BE...SO CANNOT JUSTIFY A MEASURABLE 20+ POP
ANYWHERE AT THIS TIME FRAME. WINDS ON FRIDAY WILL REMAIN FROM THE
NORTH-NORTHWEST BUT DO NOT APPEAR NEARLY AS STRONG AS THURSDAY WITH
SUSTAINED SPEEDS GENERALLY TOPPING OUT AROUND 15 MPH. AS FOR
TEMPS...MADE ONLY A SMALL DOWNWARD NUDGE TO THURSDAY NIGHT WITH
MOST AREAS 16-20 DEGREES. FRIDAY STILL SHOULD BE THE COLDEST DAY
OF THE WEEK...BUT ACTUALLY NUDGED UP VALUES A BIT IN SOME AREAS
DUE TO DECENT MIXING POTENTIAL...RANGING FROM MID 30S IN MOST NEB
ZONES TO NEAR 40 IN KS. BY MIDNIGHT FRIDAY NIGHT...ANY FLURRY RISK
SHOULD BE OVER WITH AS THE BACK EDGE OF THE LAST IN A SERIES OF
MID LEVEL SHORTWAVE TROUGHS EXITS THE AREA.
.LONG TERM...SATURDAY THROUGH TUESDAY. DRY CONDITIONS ARE FORECAST
THROUGH THE EXTENDED PERIODS. ON SATURDAY...THE PATTERN ALOFT WILL
FEATURE A TROUGH MOVING INTO THE PACIFIC NORTHWEST...RIDGING OVER
THE ROCKIES AND A LONGWAVE TROUGH FROM THE HUDSON BAY SOUTH TO THE
GULF COAST STATES. HEIGHTS WILL RISE ACROSS THE CENTRAL PLAINS OVER
THE WEEKEND AS THE WESTERN RIDGE BUILDS ONTO PLAINS AND THE COLD
AIRMASS ASSOCIATED WITH THE TROUGH TO THE EAST DEPARTS. THE RIDGE
BEGINS TO BREAK DOWN SUNDAY AS AN UPSTREAM TROUGH REACHES THE NORTH
CENTRAL ROCKIES. THIS NEXT TROUGH AND ASSOCIATED COLD FRONT CROSSES
THE CENTRAL PLAINS SUNDAY NIGHT/MONDAY...BRINGING ANOTHER ROUND OF
COLD AIR TO START THE WORKWEEK. TEMPERATURE WISE...TEMPS BEGIN TO
RECOVER ON SATURDAY BEHIND THE UPPER TROUGH...THEN SUNDAY WILL BE
THE WARMEST OF THE EXTENDED PERIODS WITH THE MILD AIRMASS IN PLACE
AHEAD OF THE NEXT APPROACHING COLD FRONT/SYSTEM. HIGHS SUNDAY ARE
LOOKING WELL ABOVE NORMAL IN THE 50S...THEN FOLLOWING COLD FROPA
TEMPS RETURN CLOSER TO FEBRUARY NORMALS FOR MON/TUES.
&&
.FIRE WEATHER...ALTHOUGH OUTRIGHT CRITICAL FIRE WEATHER
THRESHOLDS ARE CURRENTLY NOT FORECAST DURING THE NEXT FEW
DAYS...AT LEAST PARTS OF THE CWA BEAR WATCHING FOR SOME ELEVATED
TO NEAR-CRITICAL COMBINATIONS OF WIND AND RELATIVE HUMIDITY.
STARTING OFF TODAY...WEST-NORTHWEST SUSTAINED WIND SPEEDS WILL
AVERAGE 15-20 MPH IN NEARLY ALL AREAS...WITH SPORADIC TO FREQUENT
GUSTS TO 25+ MPH EXPECTED. FORTUNATELY...AFTERNOON RELATIVE
HUMIDITY VALUES ACROSS MOST OF THE ARE FORECAST TO HOLD SLIGHTLY
ABOVE CRITICAL LEVELS IN THE 25-30 PERCENT RANGE. HOWEVER...IT
COULD BE A CLOSE CALL ESPECIALLY IN PARTS OF PHILLIPS/ROOKS/OSBORNE
COUNTIES IN KANSAS...WHERE RH VALUES COULD EDGE A BIT CLOSER TO 20
PERCENT. WILL INTRODUCE AN ELEVATED FIRE DANGER MENTION INTO THE
HAZARDOUS WEATHER OUTLOOK MAINLY FOR THIS AREA. TURNING TO
THURSDAY...AS OUTLINED ABOVE STRONG SUSTAINED WINDS AROUND 30 MPH
OR HIGHER ARE FORECAST ACROSS NEARLY THE ENTIRE CWA.
FORTUNATELY...COOLER TEMPERATURES WILL KEEP AFTERNOON RH
PERCENTAGES ABOVE 30 PERCENT ACROSS NEBRASKA ZONES...BUT KS ZONES
COULD SEE VALUES CREEP DOWN CLOSER TO 25 PERCENT. BOTTOM LINE
IS...WHILE NO MAJOR FIRE DANGER ISSUES ARE ANTICIPATED THESE NEXT
FEW DAYS...SOME CAUTION MAY NEED TAKEN...AND HOURLY RELATIVE
HUMIDITY TRENDS THESE NEXT FEW AFTERNOONS WILL NEED WATCHED
CLOSELY TO MAKE SURE THERE ARE NO SURPRISES DROPPING BELOW 20
PERCENT.
&&
.PREV DISCUSSION... /ISSUED 1126 PM CST TUE FEB 12 2013/
AVIATION...06Z TAF. LOOK FOR VFR CONDITIONS THRU THE TAF PERIOD
WITH CLOUDS LIMITED TO MID/HIGH LEVELS. WINDS WILL REMAIN FROM A
WESTERLY DIRECTION BEHIND A SURFACE TROUGH.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...PFANNKUCH
LONG TERM/AVIATION...FAY
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
308 PM CST WED FEB 13 2013
.SHORT TERM...
CHALLENGE FOR THE PERIOD INCLUDE SNOW TODAY AND TONIGHT WITH
CLIPPER SYSTEMS AND THEN TEMPS THRU SATURDAY. MODELS IN OVERALL
GENERAL AGREEMENT WITH 12Z RUNS. 12Z GFS CAME AROUND IN AGREEMENT
WITH THE OVER MODELS WITH THE PLACEMENT OF TODAYS QPF. PRIMARILY
USED NAM/ECMWF FOR THE PACKAGE WITH A HEAVY LEAN TO THE RAP THRU
THIS EVENING.
CLIPPER CURRENTLY CROSSING THE CWFA IS PRODUCING VSBYS GENERALLY 1
TO 2 MILES WITH 1/2 MI IN THE STRONGEST SN. BACK EDGE OF CLIPPER
SNOW BAND JUST EXITING MINOT AREA. WILL CONTINUE WINTER WX ADVISORY
AS NEXT CLIPPER IS EXPECTED TO MOVE INTO THE DVL BSN THIS EVENING AND
STAY CONFINED TO THE WESTERN AND EXTREME SOUTHERN PORTIONS OF THE
CWFA. TOTAL 24 HOUR SNOWFALL WITH A 14 TO 1 RATIO IN THE QUARTER
TO HALF INCH QPF WILL BE IN THE 2 TO 5 INCH RANGE WITH A HIGHER
TOTAL ALONG A MADDOCK TO NEW ROCKFORD TO VALLEY CITY TO LISBON
LINE.
THE NEXT CONCERN WOULD BE WIND POTENTIAL ON THE BACK SIDE WITH BLOWING
SNOW IMPACTS. BEST COLD ADVECTION WILL LAG THE PRECIP BAND. NAM
INDICATES THE STRONGEST COLD PUSH OCCUR IN THE DVL BASIN AND ACROSS
THE WESTERN PORTIONS OF THE CWFA OVERNIGHT. THOUGH LOW LEVEL WINDS
ARE RELATIVELY WEAK WITH A SHALLOW MIXED LAYER JUST 10 TO 15 KTS
THROUGH 12Z. AS A RESULT LITTLE BLOWING SNOW IS EXPECTED.
MIXED LAYER INCREASES TOMORROW WITH BETTER MIXING...TO 20KTS TO
950MB TO 20KTS AS COLD AIR PUSHES IN WITH 925 TEMPS DROPPING 10 C
OR SO CAUSING DAYTIME TEMPS THURSDAY TO REMAIN FAIRLY STEADY OR EVEN
FALL THROUGH THE AFTERNOON.
SFC HIGH PRESSURE TO SLIDE ACROSS THE AREA FIR DAY WITH NW FLOW
ALOFT. COLD START AS NEGATIVE VALUES RETURN FOR MORNING LOWS.
LITTLE MIXING WILL LEAD TO SLOW TEMP RECOVERY FRIDAY. RETURN FLOW
SETS UP FRI AFTERNOON WEST AND WILL HELP OFFSET DIURNAL COOLING
VALLEY WEST FRIDAY NIGHT. TEMPERATURE MODERATION CONTINUES
SATURDAY AS WAA INCREASES WITH HIGHS IN THE TEENS AND 20S WEST.
.LONG TERM (SAT NIGHT-WED)...
MODELS IN REASONABLE AGREEMENT. NEXT SHORT WAVE MOVES THROUGH
SUNDAY AFTERNOON AND NIGHT. 12Z ECMWF IS COMING IN A BIT DEEPER
WITH 500 MB TROUGH AND FARTHER SOUTH WITH SFC LOW WHICH WOULD BE A
BIT HIGHER SNOW CHANCES OVER THE AREA THAN GFS/GEM. BEHIND THIS
SHORT WAVE THERE WILL BE STRONG COLD ADVECTION WITH 850 MB TEMPS
DROPPING INTO THE -18C TO -22C RANGE TUE-WED. CR ALL BLEND TEMPS
LOOK REASONABLE WITH HIGHS IN THE SINGLE DIGITS TUES-WED AND LOWS IN
THE 5 TO 15 BELOW RANGE. DISAGREEMENTS DO SHOW UP VERY LATE IN THE
PD FOR WED NIGHT-THU IN REGARDS TO NEXT 500 MB SYSTEM DIGGING INTO
THE CNTRL-SOUTHERN ROCKIES AND HOW FAR NORTH ITS IMPACT IS. GFS
WETTER AND FARTHER NORTH.
&&
.AVIATION...
AREAS OF SNOW TO IMPACT DVL-FAR REGION TONIGHT...WITH MOSTLY MVFR
VSBYS/CIGS...THOUGH BRIEF IFR VSBY PSBL. GFK-TVF-BJI TO BE ON DRY
SIDE OF THINGS AND SHOULD KEEP HIGH END VFR CLOUD DECK WITH SOME
AC/CI. WINDS WILL BE LIGHT THIS LATE AFTN BUT TURN NORTHERLY AND
INCREASE TO 10 TO 20 KTS WITH SOME HIGHER GUSTS ON THURSDAY AS COLD
ADVECTION INCREASES.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER WEATHER ADVISORY UNTIL 9 AM CST THURSDAY FOR NDZ006-014-
015-024-026-028>030-038-039-049-052-053.
MN...WINTER WEATHER ADVISORY UNTIL 9 AM CST THURSDAY FOR MNZ003-
029>031-040.
&&
$$
JK/RIDDLE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
949 AM EST WED FEB 13 2013
.SYNOPSIS...
LOW PRESSURE WILL BE CROSSING THE TENNESSEE VALLEY TO THE MID
ATLANTIC TODAY...BUT WEAK HIGH PRESSURE WILL REMAIN OVER THE
LOCAL AREA. LOW PRESSURE FROM WESTERN CANADA WILL CROSS THE GREAT
LAKES THURSDAY AND FRIDAY AND BRING TEMPERATURES BELOW NORMAL FOR
THE WEEKEND. HIGH PRESSURE WILL BE SLOW TO WORK INTO THE CENTRAL
LAKES AND OHIO VALLEY LATE IN THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ONLY MINOR CHANGES HAVE BEEN MADE TO THE GRIDS TO REFLECT CURRENT
CONDITIONS. MODELS HINTING THAT THE CLOUD COVER MAY HANG ON A BIT
LONGER THAN EARLIER THINKING SO WE LOWERED HIGHS BY A DEGREE OR TWO.
PREVIOUS DISCUSSION...
PESKY STRATUS TRAPPED UNDER THE INVERSION HAS BEEN DRIFTING
EASTWARD ALL NIGHT. MOST OF THE AREA WILL BE CLOUDY TO START THE
DAY. AND THESE SHOULD STICK AROUND THROUGH THE
MORNING...SCATTERING THIS AFTERNOON. THE HIGH CLOUDS ASSOCIATED
WITH THE LOW THAT WILL PASS TO OUR SOUTH REMAINS THIN ON THE
NORTHERN EDGE...BUT FOR THE AFTERNOON THEY WILL BE THICKER ACROSS
THE SOUTHERN THIRD TO HALF OF THE AREA...THINNER NORTH. THE BEST
OUTLOOK FOR SUN WOULD BE FOR NW OH/TOLEDO AREA LATER TODAY. AS WE
HAVE HAD THE PAST SEVERAL DAYS...FORECASTING PRECIP TO REMAIN
SOUTH OF THE AREA...AND DRY AIR IN PLACE WINNING OUT. TEMPERATURES
ARE TOUGH TODAY. HAVE STUCK WITH PREVIOUS FORECAST OF UPPER 30S
MOST PLACES. SLIGHTLY COOLER ALONG THE LAKESHORE WITH A LIGHT
NORTH FLOW. OVERALL NOT TOO FAR OFF FROM TUESDAYS HIGHS AND FAIRLY
CLOSE TO GUIDANCE. NO CHANGES FROM EARLIER.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
A DISSIPATING TROUGH FROM THE NORTHERN LAKES WILL JUST BRUSH THE
AREA TONIGHT. THIS WILL GIVE US NO TROUBLE OTHER THAN BRINGING A
FEW MID/HIGH CLOUDS ACROSS THE AREA OVERNIGHT. BY MORNING THE
RIDGE ACCESS IS TO OUR EAST AND WE HAVE SET UP A LIGHT RETURN
FLOW.
A LITTLE WEDGE OF WARMER AIR REACHES INTO IND/OH/LOWER MI ON
THURSDAY. WILL STICK WITH H8 TEMPS STILL BELOW ZERO...BUT THAT
WILL AT LEAST GET US WELL INTO THE 40S FOR HIGHS. LEANED TOWARD
THE WARMER GFSBC NUMBERS AS WE SHOULD BE ABLE TO WARM NICELY WITH
MID FEB SUN. WITH THE AFTERNOON THOUGH WE GET ONE FRONT AND SOME
LIFT THAT MAY GENERATE A FEW LIGHT RAIN SHOWERS. STILL HAVE NOT
MOISTENED THE COLUMN SO DID NOT BRING PRECIP CHANCE UP TO 40% OR
SO UNTIL LATE IN THE AFTERNOON. THE BETTER COLD FRONT...SURGE OF
COLDER AIR...AND BETTER MOISTURE ARRIVES LATE THURSDAY NIGHT. SO
LOWS THURSDAY NIGHT STILL REASONABLE IN THE LOWER 30S.
FRIDAY THOUGH WE MAY SEE LITTLE RISE AS THE BRUNT OF THE COLD AIR
ARRIVES. BASE OF TROUGH MOVES INTO THE OHIO VALLEY SO MUCH OF THE
AREA WILL SEE AT LEAST SCATTERED SNOW SHOWERS FRIDAY AND FRIDAY
NIGHT WITH SOME LIGHT ACCUMULATIONS. MORE FREQUENT SNOW SHOWERS
FOR NE OH/NW PA. SNOW SHOWERS LINGER ACROSS NE OH/NW PA INTO
SATURDAY. TEMPS BELOW NORMAL SATURDAY AND EVEN COLDER SATURDAY
NIGHT. LOOKING FOR TEENS SATURDAY NIGHT...WITH SOME SINGLE DIGITS
POSSIBLE. HIGH WILL BE BUILDING IN FROM THE WEST AT THIS POINT AND
MAY HAVE SOME CLEARING WITH IT FOR FDY AREA.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE THREAT OF SNOW SHOWERS CONTINUES ON SUNDAY OVER THE SNOW BELT.
THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR
18C...HOWEVER...THE AIRMASS IS VERY DRY...CHANCE POPS SEEM
REASONABLE. ELSEWHERE DRY AND PARTLY CLOUDY. HIGH PRESSURE WILL
BE MOVING ACROSS THE FORECAST AREA SUNDAY NIGHT. THE FLOW REMAINS
NORTHWEST BUT WE ARE IN WARM ADVECTION SUNDAY NIGHT. WILL FORECAST A
CHANCE OF FLURRIES FOR THE SNOW BELT.
A STRONG LOW WILL MOVE THROUGH THE WESTERN LAKES MONDAY NIGHT INTO
TUESDAY. MAJOR MODEL DIFFERENCES IN THE STRENGTH...TIMING AND TRACK
OF THE LOW. THIS WILL DETERMINE WHAT THE PRECIPITATION TYPE IS. AT
THIS TIME KEPT IT SNOW MONDAY NIGHT AND RAIN OR SNOW TUESDAY...BUT
THIS WILL HAVE TO BE MONITORED. IF THE GFS IS CORRECT IT COULD BE
RAIN OR FREEZING RAIN MONDAY NIGHT AND MAINLY RAIN ON TUESDAY. USED
A BLEND OF GUIDANCE FOR THE TEMPERATURES BUT CONFIDENCE IS LOW WITH
THE MODEL DISCREPANCIES.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRESSURE OVER NORTHERN OHIO WILL MOVE EAST TODAY. PLENTY OF
LOW LEVEL MOISTURE STUCK UNDER THE INVERSION WITH MVFR CEILINGS
FAIRLY WIDESPREAD. ANY AREAS THAT ARE SCATTERED WILL BECOME BROKEN
AFTER DAYBREAK. THE QUESTION IS HOW LONG WILL IT TAKE FOR THE LOW
CLOUDS TO DECREASE. THE RUC AND LAMP GUIDANCE ARE TRYING TO
INDICATE IT WILL TAKE ALL DAY FOR NW PA AND A LARGE PART OF NE OH.
THAT SEEMS OVERDONE WITH THE SUN ANGLE GETTING STRONGER AND SOME
SUBSIDENCE. WILL TRY DECREASING THE LOW CLOUDS IN THE AFTERNOON.
FOR THE SOUTHERN PORTION OF THE FORECAST AREA MID CLOUDS WILL
OCCUR BECAUSE OF THE UPPER TROF THAT WAS MOVING THROUGH THE OHIO
VALLEY TODAY. THE CLOUDS WILL DECREASE FOR A TIME LATE THIS
AFTERNOON THROUGH EARLY TONIGHT...THEN THEY WILL INCREASE AHEAD OF
THE NEXT SYSTEM.
OUTLOOK...NON-VFR THURSDAY NIGHT AND FRIDAY SHIFTING TO MAINLY
THE SNOWBELT SATURDAY NIGHT AND SUNDAY.
&&
.MARINE...
OCCASIONAL WEATHER SYSTEMS WILL MOVE THROUGH THE REGION DURING THE
PERIOD. HIGH PRESSURE WILL BE OVER THE LAKE THIS MORNING AND THEN IT
WILL MOVE EAST. A FRONTAL SYSTEM WILL MOVE ACROSS LAKE ERIE THURSDAY
NIGHT. WILL HAVE TO KEEP AN EYE ON THE WINDS...THE COLD ADVECTION IS
SOMEWHAT WEAK. THE GFS MODEL HAS THE 925 MB WINDS UP TO 40
KTS...TRYING TO FLIRT WITH GALE FORCE WINDS. HOWEVER...THE NAM MODEL
AND THE ECMWF ARE MUCH WEAKER. THIS WILL HAVE TO BE MONITORED. AT
THIS TIME KEPT THE WINDS IN THE 15 TO 25 KNOT RANGE. FOR FRIDAY
THROUGH SUNDAY THE FLOW WILL BE NORTHWEST WITH PLENTY OF COLD AIR
BUT THE WINDS WILL STAY WELL BELOW GALE FORCE SPEEDS. HIGH PRESSURE
BUILDS IN BRIEFLY SUNDAY NIGHT AND THEN A STRONG SOUTHERLY FLOW
DEVELOPS.
THE WEATHER SYSTEM FOR MONDAY NIGHT INTO TUESDAY COULD HAVE NEAR
GALE FORCE WINDS DEPENDING ON THE TRACK OF THE LOW.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...OUDEMAN
NEAR TERM...MULLEN/OUDEMAN
SHORT TERM...OUDEMAN
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
650 AM EST WED FEB 13 2013
.SYNOPSIS...
LOW PRESSURE WILL BE CROSSING THE TENNESSEE VALLEY TO THE MID
ATLANTIC TODAY...BUT WEAK HIGH PRESSURE WILL REMAIN OVER THE
LOCAL AREA. LOW PRESSURE FROM WESTERN CANADA WILL CROSS THE GREAT
LAKES THURSDAY AND FRIDAY AND BRING TEMPERATURES BELOW NORMAL FOR
THE WEEKEND. HIGH PRESSURE WILL BE SLOW TO WORK INTO THE CENTRAL
LAKES AND OHIO VALLEY LATE IN THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PESKY STRATUS TRAPPED UNDER THE INVERSION HAS BEEN DRIFTING
EASTWARD ALL NIGHT. MOST OF THE AREA WILL BE CLOUDY TO START THE
DAY. AND THESE SHOULD STICK AROUND THROUGH THE
MORNING...SCATTERING THIS AFTERNOON. THE HIGH CLOUDS ASSOCIATED
WITH THE LOW THAT WILL PASS TO OUR SOUTH REMAINS THIN ON THE
NORTHERN EDGE...BUT FOR THE AFTERNOON THEY WILL BE THICKER ACROSS THE
SOUTHERN THIRD TO HALF OF THE AREA...THINNER NORTH. THE BEST
OUTLOOK FOR SUN WOULD BE FOR NW OH/TOLEDO AREA LATER TODAY. AS WE
HAVE HAD THE PAST SEVERAL DAYS...FORECASTING PRECIP TO REMAIN
SOUTH OF THE AREA...AND DRY AIR IN PLACE WINNING OUT. TEMPERATURES
ARE TOUGH TODAY. HAVE STUCK WITH PREVIOUS FORECAST OF UPPER 30S
MOST PLACES. SLIGHTLY COOLER ALONG THE LAKESHORE WITH A LIGHT
NORTH FLOW. OVERALL NOT TOO FAR OFF FROM TUESDAYS HIGHS AND FAIRLY
CLOSE TO GUIDANCE. NO CHANGES FROM EARLIER.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
A DISSIPATING TROUGH FROM THE NORTHERN LAKES WILL JUST BRUSH THE
AREA TONIGHT. THIS WILL GIVE US NO TROUBLE OTHER THAN BRINGING A
FEW MID/HIGH CLOUDS ACROSS THE AREA OVERNIGHT. BY MORNING THE
RIDGE ACCESS IS TO OUR EAST AND WE HAVE SET UP A LIGHT RETURN
FLOW.
A LITTLE WEDGE OF WARMER AIR REACHES INTO IND/OH/LOWER MI ON
THURSDAY. WILL STICK WITH H8 TEMPS STILL BELOW ZERO...BUT THAT
WILL AT LEAST GET US WELL INTO THE 40S FOR HIGHS. LEANED TOWARD
THE WARMER GFSBC NUMBERS AS WE SHOULD BE ABLE TO WARM NICELY WITH
MID FEB SUN. WITH THE AFTERNOON THOUGH WE GET ONE FRONT AND SOME
LIFT THAT MAY GENERATE A FEW LIGHT RAIN SHOWERS. STILL HAVE NOT
MOISTENED THE COLUMN SO DID NOT BRING PRECIP CHANCE UP TO 40% OR
SO UNTIL LATE IN THE AFTERNOON. THE BETTER COLD FRONT...SURGE OF
COLDER AIR...AND BETTER MOISTURE ARRIVES LATE THURSDAY NIGHT. SO
LOWS THURSDAY NIGHT STILL REASONABLE IN THE LOWER 30S.
FRIDAY THOUGH WE MAY SEE LITTLE RISE AS THE BRUNT OF THE COLD AIR
ARRIVES. BASE OF TROUGH MOVES INTO THE OHIO VALLEY SO MUCH OF THE
AREA WILL SEE AT LEAST SCATTERED SNOW SHOWERS FRIDAY AND FRIDAY
NIGHT WITH SOME LIGHT ACCUMULATIONS. MORE FREQUENT SNOW SHOWERS
FOR NE OH/NW PA. SNOW SHOWERS LINGER ACROSS NE OH/NW PA INTO
SATURDAY. TEMPS BELOW NORMAL SATURDAY AND EVEN COLDER SATURDAY
NIGHT. LOOKING FOR TEENS SATURDAY NIGHT...WITH SOME SINGLE DIGITS
POSSIBLE. HIGH WILL BE BUILDING IN FROM THE WEST AT THIS POINT AND
MAY HAVE SOME CLEARING WITH IT FOR FDY AREA.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE THREAT OF SNOW SHOWERS CONTINUES ON SUNDAY OVER THE SNOW BELT.
THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR
18C...HOWEVER...THE AIRMASS IS VERY DRY...CHANCE POPS SEEM
REASONABLE. ELSEWHERE DRY AND PARTLY CLOUDY. HIGH PRESSURE WILL
BE MOVING ACROSS THE FORECAST AREA SUNDAY NIGHT. THE FLOW REMAINS
NORTHWEST BUT WE ARE IN WARM ADVECTION SUNDAY NIGHT. WILL FORECAST A
CHANCE OF FLURRIES FOR THE SNOW BELT.
A STRONG LOW WILL MOVE THROUGH THE WESTERN LAKES MONDAY NIGHT INTO
TUESDAY. MAJOR MODEL DIFFERENCES IN THE STRENGTH...TIMING AND TRACK
OF THE LOW. THIS WILL DETERMINE WHAT THE PRECIPITATION TYPE IS. AT
THIS TIME KEPT IT SNOW MONDAY NIGHT AND RAIN OR SNOW TUESDAY...BUT
THIS WILL HAVE TO BE MONITORED. IF THE GFS IS CORRECT IT COULD BE
RAIN OR FREEZING RAIN MONDAY NIGHT AND MAINLY RAIN ON TUESDAY. USED
A BLEND OF GUIDANCE FOR THE TEMPERATURES BUT CONFIDENCE IS LOW WITH
THE MODEL DISCREPANCIES.
&&
.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRESSURE OVER NORTHERN OHIO WILL MOVE EAST TODAY. PLENTY OF
LOW LEVEL MOISTURE STUCK UNDER THE INVERSION WITH MVFR CEILINGS
FAIRLY WIDESPREAD. ANY AREAS THAT ARE SCATTERED WILL BECOME BROKEN
AFTER DAYBREAK. THE QUESTION IS HOW LONG WILL IT TAKE FOR THE LOW
CLOUDS TO DECREASE. THE RUC AND LAMP GUIDANCE ARE TRYING TO
INDICATE IT WILL TAKE ALL DAY FOR NW PA AND A LARGE PART OF NE OH.
THAT SEEMS OVERDONE WITH THE SUN ANGLE GETTING STRONGER AND SOME
SUBSIDENCE. WILL TRY DECREASING THE LOW CLOUDS IN THE AFTERNOON.
FOR THE SOUTHERN PORTION OF THE FORECAST AREA MID CLOUDS WILL
OCCUR BECAUSE OF THE UPPER TROF THAT WAS MOVING THROUGH THE OHIO
VALLEY TODAY. THE CLOUDS WILL DECREASE FOR A TIME LATE THIS
AFTERNOON THROUGH EARLY TONIGHT...THEN THEY WILL INCREASE AHEAD
OF THE NEXT SYSTEM.
OUTLOOK...NON-VFR THURSDAY NIGHT AND FRIDAY SHIFTING TO MAINLY
THE SNOWBELT SATURDAY NIGHT AND SUNDAY.
&&
.MARINE...
OCCASIONAL WEATHER SYSTEMS WILL MOVE THROUGH THE REGION DURING THE
PERIOD. HIGH PRESSURE WILL BE OVER THE LAKE THIS MORNING AND THEN IT
WILL MOVE EAST. A FRONTAL SYSTEM WILL MOVE ACROSS LAKE ERIE THURSDAY
NIGHT. WILL HAVE TO KEEP AN EYE ON THE WINDS...THE COLD ADVECTION IS
SOMEWHAT WEAK. THE GFS MODEL HAS THE 925 MB WINDS UP TO 40
KTS...TRYING TO FLIRT WITH GALE FORCE WINDS. HOWEVER...THE NAM MODEL
AND THE ECMWF ARE MUCH WEAKER. THIS WILL HAVE TO BE MONITORED. AT
THIS TIME KEPT THE WINDS IN THE 15 TO 25 KNOT RANGE. FOR FRIDAY
THROUGH SUNDAY THE FLOW WILL BE NORTHWEST WITH PLENTY OF COLD AIR
BUT THE WINDS WILL STAY WELL BELOW GALE FORCE SPEEDS. HIGH PRESSURE
BUILDS IN BRIEFLY SUNDAY NIGHT AND THEN A STRONG SOUTHERLY FLOW
DEVELOPS.
THE WEATHER SYSTEM FOR MONDAY NIGHT INTO TUESDAY COULD HAVE NEAR
GALE FORCE WINDS DEPENDING ON THE TRACK OF THE LOW.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...OUDEMAN
NEAR TERM...OUDEMAN
SHORT TERM...OUDEMAN
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
938 AM EST WED FEB 13 2013
.DISCUSSION...14Z SURFACE MAP SHOWS LOW PRESSURE NOW CENTERED OVER
SW VA...AND THIS SURFACE LOW SHOULD TRACK NE OVER THE NEXT FEW
HOURS. MAIN AREA OF REMAINING LIGHT RAIN SHOWERS HAS LIFTED NORTH OF
THE SRN 2/3RDS OF THE FORECAST AREA. LATEST RUC MODEL RUN SHOWS GOOD
COVERAGE OF LIGHT RAIN OVER NRN PLATEAU...EXTREME NE TN AND SW VA
THIS AFTERNOON...AS SOME RAIN WRAPS AROUND ON THE BACK SIDE OF THE
EXITING LOW PRESSURE SYSTEM.
PLAN TO UPDATE FORECAST GRIDS SHORTLY...AND I MAY NEED TO LOWER RAIN
CHANCES ACROSS SE TN AND SW NC BY AT LEAST 20 PERCENT. WILL KEEP
HIGH LIKELY TO LOW CATEGORICAL CHANCES OVER NRN PARTS OF E TN INTO
SW VA. HOURLY TEMPS ARE RUNNING VERY CLOSE TO GRIDS AND MAX TEMPS
APPEAR ON TRACK.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 52 33 57 35 54 / 70 10 10 10 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 47 32 54 34 50 / 90 20 10 10 20
OAK RIDGE, TN 47 32 54 33 50 / 90 20 10 10 10
TRI CITIES AIRPORT, TN 46 29 50 31 47 / 90 40 10 10 30
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
443 AM EST WED FEB 13 2013
.SYNOPSIS...
LOW PRESSURE OVER ALABAMA WILL TRACK NORTHEAST INTO VIRGINIA THIS
AFTERNOON...THEN OFF THE EAST COAST TONIGHT. THIS SYSTEM EXITS
THURSDAY MORNING. ANOTHER LOW CROSSING THROUGH THE GREAT LAKES
WILL PUSH A COLD FRONT THROUGH THE REGION ON FRIDAY AND SATURDAY.
HIGH PRESSURE WILL BE OVER THE AREA ON SUNDAY AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 430 AM EST WEDNESDAY...
PERSISTENT BAND OF RAIN OVER THE SOUTHERN COUNTY WARNING AREA WAS
ORIENTED ALONG AND WELL NORTH OF THE WARM FRONT. DON`T EXPECT MUCH
EXPANSION OF THE AREAL COVERAGE OF PRECIPITATION UNTIL THE UPPER
LOW GETS CLOSER. LOCAL WRF FROM 00Z ALONG WITH RAP MODELS AND
BUFKIT HAVE MORE WIDESPREAD PRECIPITATION ARRIVING IN THE WESTERN
COUNTY WARNING AREA AROUND 7AM AND REACHING EASTERN COUNTIES
BEFORE NOON.
DURING THE DAY THE SURFACE LOW MOVES FROM ALABAMA THIS MORNING
INTO SOUTHWEST VIRGINIA THIS AFTERNOON. FORECAST AREA STAYS NORTH
OF THE WARM FRONT. EXPECT ENOUGH EAST TO SOUTHEAST SURFACE AND LOW
LEVEL WINDS TO ENHANCE THE PRECIPITATION AMOUNTS ON EASTERN SLOPES
THROUGH 00Z/7PM TONIGHT. BEST SYNOPTIC LIFT ARRIVES WITH THE UPPER
LOW.
MODELS MORE IN LINE WITH TEMPERATURE PROFILE TODAY AND TONIGHT.
MAINLY USED A NAM/RAP BLEND FOR TEMPERATURES AND PRECIPITATION
TYPE...WHICH WAS SLIGHTLY COOLER THAN THE GFS. EVEN THE COOLER
GUIDANCE LIMITED ANY WINTER PRECIPITATION TO THE VERY HIGHEST
ELEVATIONS FROM NORTHWEST NORTH CAROLINA INTO TAZEWELL
COUNTY...AND FROM MERCER COUNTY INTO BATH COUNTY. THE COMBINATION
OF STRATIFORM SNOWFALL FROM THE UPPER LOW TODAY AND UPSLOPE SNOW
SHOWERS THIS EVENING STILL SUPPORTS SNOW ACCUMULATIONS THAT REACH
ADVISORY CRITERIA ONLY IN GREENBRIER COUNTY. SO NO CHANGES TO THE
ADVISORY NEEDED AT THIS TIME.
STAYED COOLER THAN GUIDANCE FOR BOTH HOURLY TEMPERATURES AND
MAXIMUM TEMPERATURES FOR TODAY. MORE TYPICAL DIURNAL/COLD AIR
ADVECTION TREND EXPECTED FOR TONIGHT.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 400 AM EST WEDNESDAY...
BY SUNRISE THURSDAY...EXPECT TO SEE SNOW SHOWER ACTIVITY ACROSS THE
MOUNTAINS COMING TO AN END AND WIND SPEEDS DIMINISHING AS HIGH
PRESSURE...BUILDING IN FROM THE GULF COAST REGION...BECOMES THE
DOMINANT FEATURE OF THE MOMENT IN OUR PROGRESSIVE WEATHER PATTERN.
RELATIVELY ZONAL FLOW ALOFT WILL HELP MAINTAIN MILD TEMPERATURES...
AND EXPECT AFTERNOON HIGHS TO RANGE FROM THE MID TO UPPER 40S ACROSS
THE MOUNTAINS...TO THE MID 50S ACROSS THE PIEDMONTS.
COME EARLY FRIDAY AFTERNOON HOWEVER...WE CAN EXPECT ANOTHER STRONG
COLD FRONT TO MOVE ACROSS THE AREA...USHERING IN A SHOT OF ARCTIC
AIR. WITH THE ARRIVAL OF THE COLD FRONT...WILL ALSO SEE ANOTHER
ROUND OF SNOW SHOWERS DEVELOP ACROSS THE MOUNTAINS...WITH THE
HIGHEST SNOWFALL AMOUNTS OCCURRING IN THE USUAL NORTHWEST WIND
UPSLOPE AREAS. WINDS WILL ALSO BE ON THE GUSTY SIDE THROUGH THE DAY
THANKS TO A 5MB TO 6MB PRESSURE GRADIENT ACROSS THE AREA BETWEEN LOW
PRESSURE OVER EASTERN CANADA...AND HIGH PRESSURE BUILDING ACROSS THE
PLAINS. GUSTY WINDS WILL CONTINUE THROUGH FRIDAY NIGHT AND EARLY
SATURDAY MORNING...CAUSING WIND CHILL TEMPERATURES TO RANGE FROM THE
POSITIVE SINGLE DIGITS IN SOUTHEAST WEST VIRGINIA...TO THE 20S
ACROSS THE PIEDMONTS.
MOUNTAIN SNOW SHOWER ACTIVITY WILL CONTINUE ON SATURDAY...AND
BELIEVE THAT PORTIONS OF OUR FORECAST AREA FROM THE NORTH CAROLINA
MOUNTAINS THROUGH THE ALLEGHANY HIGHLANDS WILL HAVE A HARD TIME
RISING ABOVE FREEZING FOR DAYTIME HIGHS THANKS TO A DEEP UPPER LEVEL
TROUGH BUILDING SOUTHWARD FROM EASTERN CANADA THROUGH THE GULF
COAST. THE TROUGH REMAINS PROGRESSIVE HOWEVER...AND WILL CONTINUE AN
EASTWARD JOG THROUGH SATURDAY NIGHT...EVENTUALLY PUSHING OFF THE
ATLANTIC COAST BY SUNDAY MORNING.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 400AM EST WEDNESDAY...
A PATTERN CHANGE TO RIDGING IN THE EAST STILL LOOKS PROMISING AS
WE HEAD INTO EARLY NEXT WEEK. TEMPERATURES WILL START TO TREND
MILDER...AND PRECIPITATION WILL START TO ENTER THE REGION MONDAY
NIGHT IN THE WEST AS SOUTHERLY WINDS START TO ADVECT MOISTURE FROM
THE GULF IN ADVANCE OF OUR NEXT APPROACHING TROUGH. A COLD FRONT
IS EXPECTED TO BE ON OUR WESTERN DOORSTEP BY LATE TUESDAY
AFTERNOON. EXPECT INCREASING CHANCE OF SHOWERS THROUGH THE
DAY...THE THE BEST COVERAGE IN THE WEST. THE CHANCES OF A GUSTY
DAY LOOK PROMISING AS FORECAST 850 MB WINDS AHEAD OF THE FRONT ARE
IN THE 60 TO 70 KT RANGE. WHILE GUIDANCE DOES NOT INDICATE WE WILL
HAVE MUCH IN THE WAY OF INSTABILITY...LOW LEVEL SHEAR WILL LIKELY
BE HIGH.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
AS OF 100 AM EST WEDNESDAY...
RADAR IMAGERY INDICATES THAT THE FIRST ROUND OF PRECIPITATION HAS
PASSED THE AREA THIS MORNING...REMAINING CONFINED MAINLY TO NORTH
CAROLINA AND EXTREME SOUTHERN VIRGINIA...AND PASSING ACROSS DAN.
CURRENTLY LOOKING AT MAINLY VFR CEILINGS...BUT EXPECT THAT TO
CHANGE BEFORE SUNRISE AS AN APPROACHING UPPER TROUGH...AND
ASSOCIATED SURFACE LOW...MOVES INTO THE AREA. LOW END MVFR AND
IFR CEILINGS WILL DEVELOP DURING THE 09Z TO 12Z TIME FRAME AS
SOUTHEASTERLY WIND FLOW ACROSS THE AREA INCREASES. PRECIPITATION...
MAINLY IN THE FORM OF RAIN MIXED OCCASIONALLY WITH SLEET OR
SNOW...WILL BECOME WIDESPREAD THROUGH THE DAY AS THE LOW PASSES
THE AREA DURING THE AFTERNOON.
AS THE LOW MOVES TO THE COAST DURING THE EVENING...WINDS WILL
SHIFT NORTHWESTERLY...BRINGING COLDER AIR INTO THE AREA AND
CAUSING RAIN TO CHANGE TO SNOW SHOWERS. WILL LIKELY BE LOOKING A
BRIEF PERIOD OF SNOW FOR ROA...DAN AND LYH BEFORE MOISTURE MOVES
OUT OF THE AREA...HOWEVER SNOW SHOWERS WILL LINGER THROUGH THE
NIGHT FURTHER TO THE WEST. EXPECT SNOW SHOWERS TO END AT ALL
AIRPORTS BY SUNRISE THURSDAY. WILL ALSO EXPERIENCE GUSTY WINDS
THROUGH THE NIGHT THANKS TO A TIGHT PRESSURE GRADIENT BETWEEN THE
DEPARTING LOW AND APPROACHING HIGH PRESSURE.
AN ARCTIC COLD FRONT IS EXPECTED TO CROSS THE REGION FRIDAY NIGHT
WITH GUSTY WINDS...AND PERHAPS A PERIOD OF MOUNTAIN MVFR CIGS
INCLUDING SNOW OR SNOW SHOWERS INTO SATURDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR WVZ045.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...NF
LONG TERM...DS
AVIATION...DS/NF/WP
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
904 PM CST THU FEB 14 2013
.UPDATE...
CLEARING IS ON THE WAY FOR LATER TONIGHT. TEMPS CURRENTLY HELD UP
DUE TO THE CLOUD COVER...BUT THE CLEARING AND LIGHTER WINDS TOWARD
MORNING SHOULD ALLOW FOR A QUICK DROP. OTHERWISE NO MAJOR CHANGES
TONIGHT.
&&
.AVIATION/06Z TAFS/...
BKN VFR CLOUDS WILL GRADUALLY CLEAR FROM WEST TO EAST THROUGH THE
REMAINDER OF TONIGHT. THEN MORE CLOUDS SPREAD BACK IN WITH THE
ARRIVAL OF ANOTHER SHORT WAVE. THESE COULD DROP DOWN TO MVFR
LEVELS FRIDAY EVENING.
&&
.PREV DISCUSSION... /ISSUED 353 PM CST THU FEB 14 2013/
SHORT TERM...
TONIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM.
SURFACE LOW MOVES NORTHEAST FROM LAKE HURON TO SOUTHERN QUEBEC AS
HIGH PRESSURE BUILDS INTO THE NORTHERN AND CENTRAL PLAINS. DECENT
SHORTWAVE MOVING BY JUST TO OUR SOUTHWEST EARLY THIS EVENING.
HOWEVER...APPEARS PRECIP...OTHER THAN FLURRIES...WILL STICK TO OUR
SOUTHWEST. MODELS AGREE ON KEEPING MAIN AREA OF PRECIP TO THE
SOUTHWEST. ALSO...EXTRAPOLATION OF CURRENT SWATH OF LIGHT SNOW
ASSOCIATED WITH VORT MAX OVER CENTRAL IOWA WOULD SHOW MAIN AREA OF
PRECIP MOVING TO OUR SOUTHWEST.
LIGHT SNOW/FLURRIES WRAPPING AROUND THE LOW IN EAST CENTRAL
WISCONSIN WILL EXIT THIS EVENING AS THE LOW LIFTS NORTHEAST.
HOWEVER...KEPT FLURRY MENTION IN FOR THE NIGHT UNTIL DRY AIR
CURRENTLY IN MINNESOTA MOVES IN.
THE CLEARING AREA IN MINNESOTA HAS EXPANDED...AND MATCHES UP WELL
WITH THE RAP 850MB RH. WOULD HAVE THIS GETTING TO OUR WEST/NORTHWEST
AREA SOMETIME AROUND MIDNIGHT...PUTTING A HALT TO FLURRIES AS IT
MOVES IN. THIS COULD CREATE A PROBLEM FOR TONIGHT/S LOWS...COULD SEE
TEMPS REALLY DROP IF SIGNIFICANT CLEARING TAKES PLACE.
A WEAKER SHORTWAVE MOVES THROUGH TOMORROW AFTERNOON...SO EXPECTING
CLOUD COVER TO INCREASE FRIDAY MORNING WITH FLURRIES RETURNING.
THERE IS SOME PVA AND WAA BETWEEN 850 AND 700MB IN THE
AFTERNOON...BUT OVERALL NOT IMPRESSED BY Q VECTOR CONVERGENCE.
925MB COLD AIR ADVECTION TAKES HOLD TONIGHT. 925MB TEMPS DROP FROM
AROUND -3 TO -5C AT 00Z FRIDAY TO -11 TO -13C BY 12Z FRIDAY. NOT TOO
MUCH OF A REBOUND FOR FRIDAY EITHER. HIGHEST 925MB TEMPS ON FRIDAY
ABOUT -10 TO -12C. HOWEVER...MODELS HAVE BEEN A BIT COOL WHERE SNOW
PACK ISN/T AS SIGNIFICANT. PUT IN HIGHS IN THE 22-27F RANGE.
SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
SOUTHERN WISCONSIN IS ON THE WESTERN PERIPHERY OF THE LARGE UPPER
TROUGH AXIS. MODELS SHOW SHEARED CYCLONIC VORTICITY AXIS MOVING
ACROSS SOUTHERN WISCONSIN. SATURATED LOW LEVELS BELOW AN INVERSION
AROUND 5 THSD FT WITH STEEP LAPSE RATES BELOW THE INVERSION. SOME
FLURRY POTENTIAL.
SURFACE RIDGE AXIS THEN NUDGES INTO WESTERN WISCONSIN BY THE END
OF THE DAY.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE...MEDIUM
TO HIGH
THE HIGH PRESSURE RIDGE SHIFTS EAST OF AREA WITH THE PLAINS
TROUGH APPROACHING. WARM ADVECTION UNDERWAY THROUGH THIS PERIOD.
WARMEST 925 TEMPS ARRIVE SUNDAY NIGHT WITH READINGS RISING TO AT
OR ABOVE 0 CELSIUS. SHOULD BE A NON DIURNAL TEMPERATURE TREND
WITH RISING TEMPERATURES.
MONDAY AND MONDAY NIGHT FORECAST CONFIDENCE...MEDIUM TO HIGH
THE MID/UPPER LEVEL UPPER TROUGH EXITS THE NORTHERN AND CENTRAL
PLAINS MONDAY AND MOVES INTO THE WESTERN GREAT LAKES MONDAY NIGHT.
A DECENT SURGE OF MOISTURE ADVECTS NORTHWARD AHEAD AND ALONG OF
THE LOWER LEVEL TROUGH. GFS/GEM AND ECMWF ALL SHOW PRECIP ARRIVING
MONDAY AFTERNOON AND MONDAY NIGHT. THICKNESS AND 850 MB
TEMPERATURES TREND TOWARD A MIX OR MAINLY SNOW EXCEPT FAR
SOUTHEAST. HOWEVER GFS FORECAST SOUNDING SHOW A WARM BOUNDARY
LAYER WHICH WOULD BRING MORE RAIN SOUTH AND RAIN/SNOW NORTH.
850/925 TEMPS THEN COLLAPSE DURING THE EVENING TRANSITIONING THE
PRECIPITATION TO SNOW.
LONG TERM...
TUESDAY...FORECAST CONFIDENCE...MEDIUM
LINGERING CYCLONIC FLOW FROM THE DEPARTING MID LEVEL TROUGH SUGGESTS
KEEPING SOME SMALL POPS EAST FOR SNOW SHOWERS EARLY. THEN
PRONOUNCED DRYING. DECENT COLD ADVECTION EXPECTED BEHIND THE
STRENGTHENING LOW TO THE EAST/NORTHEAST.
WEDNESDAY...FORECAST CONFIDENCE...
BROAD CYCLONIC FLOW MOVES OFF AS A MID LEVEL RIDGE MOVES ACROSS
WISCONSIN. A RATHER STRONG CANADIAN HIGH WILL BE RIDGING SOUTHEAST
INTO THE AREA CONTINUING THE COLD TEMPERATURES.
THURSDAY...FORECAST CONFIDENCE...
STRONG SHORTWAVE OVER THE SOUTHWEST U.S. LIFTS NORTHEAST. MAIN
DIFFERENCE IS THAT THE 12Z ECMWF IS SOMEWHAT SLOWER AND FARTHER SOUTH.
GFS AND ECMWF BOTH BRING A STRONG LOW THAT WOULD FAVOR HEAVY SNOW
EVENTUALLY AFFECTING PORTIONS OF THE FORECAST AREA. THE ECMWF IS A
FAVORABLE TRACK FOR HEAVY SNOW OVER SOUTHEAST WISCONSIN...WITH THE
GFS A LITTLE FARTHER NORTH. HEAVY PRECIPITATION AMOUNTS ON BOTH
MODELS...WITH THE HEAVIEST ON THE GFS. THIS WILL BE A POTENTIAL
SNOWSTORM FOR LATER THURSDAY OR FRIDAY. PREFER THE SOMEWHAT SLOWER
ECMWF SO WILL NOT RAISE POPS FROM THE CONSENSUS GRIDS ON THURSDAY.
AVIATION/00Z TAFS/...
VFR CEILINGS WERE WEST OF ABOUT A JANESVILLE TO GREEN LAKE LINE
AROUND MID AFTERNOON. THINKING THESE CONDITIONS WILL SPREAD EAST
THIS EVENING AS THE SURFACE LOW MOVES EAST. NAM AND GFS SOUNDINGS
QUITE DIFFERENT IN TERMS OF CEILING HEIGHT. THINKING THE SOLUTION IS
SOMEWHERE IN THE MIDDLE BASED ON UPSTREAM OBS. LEANING TOWARDS VFR
CONDITIONS FOR THE MAJORITY OF THE NIGHT ONCE THE LOW MOVES EAST.
AREA OF DRY AIR OVER MINNESOTA HAS EXPANDED AND WILL LIKELY ARRIVE
IN OUR AREA AFTER MIDNIGHT. MORE CONFIDENT IN VFR CONDITIONS THEN.
COULD SEE SCATTERED FLURRIES TONIGHT UNTIL DRY AIR OVER MINNESOTA
MOVES IN. NOT EXPECTING ANY ACCUMULATION AT THE TAF SITES THOUGH.
CLOUDS WILL BUILD BACK IN FRIDAY MORNING AS ANOTHER SHORTWAVE
APPROACHES. THIS WILL BRING ANOTHER CHANCE FOR FLURRIES AS WELL. NOT
EXPECTING MUCH IF ANY ACCUMULATION.
MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH MIDNIGHT TONIGHT AS LOW
PRESSURE MOVES OFF TO THE NORTHEAST. SOUNDINGS SHOW WIND GUSTS
DIMINISHING AFTER MIDNIGHT. HOWEVER...THE PRESSURE GRADIENT IS STILL
FAIRLY TIGHT THROUGH FRIDAY MORNING AND THERE COULD BE A FEW GUSTS
TO CRITERIA AFTER MIDNIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646.
&&
$$
UPDATE...CRAVEN
TONIGHT/FRIDAY AND AVIATION/MARINE...MEB
FRIDAY NIGHT THROUGH THURSDAY...HENTZ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
535 PM CST THU FEB 14 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY
237 PM CST THU FEB 14 2013
MAIN FORECAST CONCERNS FOR THE SHORT TERM PERIOD:
1. TEMPERATURE AND CLOUD TRENDS THROUGHOUT
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING JUST OFF THE WEST COAST OF THE U.S. INTO BRITISH
COLUMBIA...WHILE TROUGHING COVERED MUCH OF EASTERN CANADA INTO THE
NORTHERN PLAINS AND WESTERN GREAT LAKES REGION. COMING THROUGH THE
TROUGH WAS A SHORTWAVE TROUGH APPROACHING THE SIOUX FALLS SOUTH
DAKOTA AREA...WHILE ANOTHER SHORTWAVE WAS SEEN IN CENTRAL
SASKATCHEWAN. THE SHORTWAVE THAT AFFECTED THE AREA LAST NIGHT INTO
THIS MORNING HAS MOVED OFF INTO LOWER MICHIGAN. RADAR IMAGERY SHOWED
A FEW RAIN/SNOW SHOWERS OVER MUCH OF WISCONSIN IN THE WAKE OF THE
LOWER MICHIGAN SHORTWAVE...DUE TO CYCLONIC FLOW OF LOW LEVEL
MOISTURE AND STEEP LOW LEVEL LAPSE RATES. TO THE WEST...RADAR ALSO
SHOWS A BAND OF RAIN/SNOW FROM CENTRAL SOUTH DAKOTA INTO NORTHWEST
IOWA...ASSOCIATED WITH THE SIOUX FALLS SHORTWAVE. NORTHWEST LOW
LEVEL WINDS BETWEEN THE TWO SHORTWAVES ARE GRADUALLY BRINGING IN
COLDER AIR. SOUNDINGS AT BIS...ABR...MPX AND INL ALL HAD 850MB TEMPS
DROP 3-4C BETWEEN 00Z AND 12Z...ALL BETWEEN -7 AND -12C AS OF 12Z.
SOME DRIER AIR WAS ALSO ACCOMPANYING THE NORTHWEST WINDS...NOTED BY
SATELLITE IMAGERY SHOWING CLEARING ACROSS NORTHERN MN.
TONIGHT THROUGH SATURDAY DEFINITELY ARE GOING TO BE COLDER THAN
AS OF LATE. THE SHORTWAVE OVER CENTRAL SASKATCHEWAN COMBINED WITH
ANOTHER SHORTWAVE CURRENTLY UP IN NORTHERN MANITOBA ARE GOING TO
DIG SOUTH...CARVING OUT A DEEP TROUGH OVER THE REGION BY 00Z
SATURDAY. 850MB TEMPS FALL AS THIS TROUGH FORMS...DROPPING TO -14
TO -18C BY 18Z FRIDAY AND -16 TO -20C BY 12Z SATURDAY PER MODEL
CONSENSUS. THOSE AT 12Z SATURDAY ARE 1.5 STANDARD DEVIATIONS BELOW
NORMAL. THE ONLY MITIGATING FACTOR TO THE COLD AIR WOULD BE THE
LACK OF SNOW OVER THE SOUTHWEST HALF OF THE FORECAST AREA...WHICH
IF SOME SUN CAN OCCUR WOULD REALLY HELP TO BOOST TEMPS UP GIVEN
THE CLIMBING SUN ANGLE NOW. GENERALLY FOLLOWED A BLEND OF THE
ECMWF AND 30 DAY BIAS CORRECTED GFS GRIDDED MOS GUIDANCE DATA
SINCE THEY HAVE BEEN DOING WELL AS OF LATE FOR HIGHS. LOWS ARE
HIGHLY CONTINGENT ON CLOUD COVER. AFTER SOME CLEARING TONIGHT...
MORE LOW TO MID CLOUDS MOVE IN FROM THE NORTHWEST FOR FRIDAY AND
FRIDAY NIGHT...ASSOCIATED WITH THAT SHORTWAVE DROPPING DOWN OUT OF
MANITOBA. THESE CLOUDS COMBINED WITH A NORTHWEST BREEZE SHOULD
HELP KEEP LOWS FROM BOTTOMING OUT...THUS A BLEND OF GUIDANCE FOR
LOWS SEEMS REASONABLE.
HANDLING CLOUD COVER SATURDAY COULD BE TRICKY. A RIDGE OF HIGH
PRESSURE IS PROGGED TO BUILD INTO THE WESTERN PORTIONS OF THE
FORECAST AREA. WILL FOLLOW THE GENERAL MODEL CONSENSUS OF THE LOW
CLOUDS BREAKING UP THROUGH THE DAY...DUE TO A COMBINATION OF THE LOW
LEVEL FLOW BECOMING ANTICYCLONIC AND DAYTIME MIXING. HOWEVER...IT IS
POSSIBLE THE CLOUDS COULD HANG ON FOR MUCH OF THE DAY. THIS COMBINED
WITH 850MB TEMPS STILL ONLY BETWEEN -14C WEST TO -20C EAST AT 18Z
WILL KEEP TEMPERATURES SEASONABLY COOL.
FOR SATURDAY NIGHT AND SUNDAY...A POTENT SHORTWAVE TROUGH IS PROGGED
TO DROP INTO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES...FORMING
TWO DISTINCT LOW PRESSURE AREAS ACROSS THE PLAINS DURING THE DAY
SUNDAY. A SOUTHERLY LOW LEVEL JET WILL DEVELOP AHEAD OF THESE TWO
LOWS...BRINGING UP WARMER AIR. AN INCREASE OF MID AND HIGH CLOUDS
ARE LIKELY TO ACCOMPANY THIS WARM ADVECTION. SO THE QUESTION FOR
LOWS SATURDAY NIGHT IS TIMING OF WHEN THE WARM ADVECTION STARTS UP
AND MID CLOUDS MOVE IN...VERSUS THE DEPARTURE TO THE EAST OF THE
SURFACE RIDGE. OUR WISCONSIN COUNTIES HAVE THE BEST SHOT OF
FAVORABLE RADIATIONAL COOLING CONDITIONS...THUS LEANED TOWARDS THE
COLDER SIDE OF GUIDANCE THERE. TEMPERATURES SHOULD RISE FROM LATE
SATURDAY NIGHT THROUGH SUNDAY AT MOST LOCATIONS AS SOUTHERLY WINDS
INCREASE. QUESTION ON SUNDAY IS HOW WARM DO WE GET...WITH 850MB
TEMPS THAT COULD APPROACH 0C NEAR CHARLES CITY IA BY 00Z MONDAY. IT
APPEARS SUNSHINE WILL BE ON THE INCREASE WEST OF THE MS RIVER AS THE
MID CLOUD LIFTS TO THE NORTH. GIVEN THE LACK OF SNOW OVER THE
SOUTHWEST HALF OF THE FORECAST AREA...LEANED MORE TOWARDS THE
CONSISTENTLY WARM ECMWF...BRINGING HIGHS AT LEAST TO THE MID 30S
AROUND CHARLES CITY.
PRECIPITATION WISE...MUCH OF THE SHORT TERM LOOKS DRY WITH RESPECT
TO REACHING 0.01" OF LIQUID EQUIVALENT IN ANY 12 HOUR PERIOD.
FLURRIES LOOK LIKELY...HOWEVER...FOR FRIDAY AND FRIDAY NIGHT OUT OF
THOSE LOW CLOUDS SINCE THEY EXIST WITHIN THE DENDRITIC GROWTH ZONE
AND HAVE WEAK LIFT FROM THE SHORTWAVE. PREVIOUS FORECAST MENTIONED
CONCERN THAT AS THE WARM ADVECTION STARTS UP SATURDAY NIGHT THAT WE
COULD SEE SOME SNOW FALL OUT OF THE ASSOCIATED MID CLOUD DECK. THAT
STILL REMAINS A CONCERN...THOUGH THINK FLURRIES WOULD BE THE MOST
THAT GETS PRODUCED. THEN AGAIN...THESE FLURRIES MIGHT BE ABSORBED BY
LOWER LEVEL DRY AIR. FOR NOW HAVE KEPT THE FORECAST DRY FOR SATURDAY
NIGHT AND SUNDAY.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
237 PM CST THU FEB 14 2013
MAIN CONCERNS FOR THE LONG TERM PERIOD...
1. TEMPERATURES AND PRECIPITATION POTENTIAL THROUGH MONDAY
2. BRIEF ARCTIC AIR SHOT FOR MID-WEEK
3. POTENTIAL FOR A WINTER STORM TO IMPACT THE AREA LATE IN THE WEEK
VERY GOOD MODEL AGREEMENT EXISTS AMONGST THE 14.12Z
ECMWF/GFS/CANADIAN/UKMET THROUGHOUT MUCH OF THE LONG TERM PERIOD.
FOR SUNDAY NIGHT INTO MONDAY...THE TROUGHING THAT WAS COMING ACROSS
THE NORTHERN ROCKIES EVOLVES BY MONDAY EVENING INTO A FULL
LONGITUDINAL TROUGH ACROSS THE CANADIAN AND U.S. PLAINS. THIS
TROUGHING EVENTUALLY PHASES TOGETHER AS IT CROSSES THE REGION AND
HEADS INTO THE GREAT LAKES FOR TUESDAY. PRIOR TO THE PHASING...A
REALLY STRONG PUSH OF WARM AIR COMES UP AT THE REGION WITH 850MB
TEMPS BETWEEN -2C AND +4C AT 12Z MONDAY. HAVE BOOSTED HIGH
TEMPERATURES FOR MONDAY AS A RESULT...THOUGH COULD BE EVEN HIGHER AS
NOTED BY THE 14.12Z ECMWF. ALSO...MODELS CONTINUE TO TREND
FARTHER WEST WITH THE SOUTHERN LOW COMING OUT OF THE SOUTHERN
PLAINS. AS SUCH...NOW ABOUT THE EASTERN TWO THIRDS OF THE AREA IS
AFFECTED BY LIGHT PRECIPITATION FOR MONDAY AFTERNOON AND EVENING.
THUS...HAVE EXPANDED LOW PRECIPITATION CHANCES FARTHER WEST AND
RAISED THEM 5-10 PERCENT. IF TRENDS CONTINUE...THESE CHANCES WILL
NEED TO BE RAISED MORE. WITH THE WARMER TEMPERATURES TOO...MIXING
WITH OR CHANGING TO RAIN IS AN ISSUE AS WELL.
AS THE PHASED TROUGH FORMS OVER THE AREA MONDAY NIGHT AND TUESDAY...
ARCTIC AIR FLOWS INTO THE REGION. 850MB TEMPS PLUMMET TO -12 TO -14C
BY 12Z TUESDAY AND -14 TO -20C BY 12Z WEDNESDAY. THUS...A MUCH
COOLER PERIOD IS ON TAP AGAIN. CANADIAN HIGH PRESSURE BUILDING DOWN
INTO THE NORTHERN PLAINS...IN THE WAKE OF THE PHASED TROUGH...WILL
PROVIDE FOR BLUSTERY CONDITIONS. WIND CHILLS RIGHT NOW LOOK TO STAY
JUST ABOVE ADVISORY CRITERIA...BOTTOMING OUT AT MOST IN THE -15 TO
-20F RANGE WEDNESDAY MORNING.
LASTLY...ABOUT THE POTENTIAL WINTER STORM LATE IN THE WEEK. THERE IS
SURPRISINGLY CONSISTENT AND GOOD MODEL AGREEMENT AMONGST THE
ECMWF...GFS AND THEIR RESPECTIVE ENSEMBLES OF A DEEP TROUGH FORMING
OVER THE WESTERN U.S. ON WEDNESDAY. AS THIS TROUGH HEADS EAST
TOWARDS THE PLAINS...A DEEP LOW PRESSURE AREA DEVELOPS OVER THE
CENTRAL PLAINS BY THURSDAY MORNING. THERE ARE A FEW QUESTIONS FROM
HERE ON...WHICH MAY TAKE AT LEAST A FEW MORE DAYS TO ANSWER:
1. TIMING AND STRENGTH AS USUAL
2. HOW QUICK DOES THE PRECIPITATION SPREAD INTO THE AREA IF IT
INDEED AFFECTS US
3. HOW MUCH PRECIPITATION WOULD OCCUR
4. DEPENDING ON HOW MUCH THE SYSTEM WRAPS UP...MAY HAVE TO DEAL WITH
PRECIPITATION TYPE ISSUES
FOR NOW HAVE STAYED WITH A CONSENSUS APPROACH...WHICH BY THURSDAY
NIGHT YIELDS 50-60 PERCENT CHANCES OF PRECIPITATION REGION-WIDE. ALL
PRECIPITATION RIGHT NOW LOOKS TO FALL AS SNOW...WHICH COULD BE
SIGNIFICANT. SINCE THE STORM IS VERY FAR OUT IN THE FORECAST AND
JUST BEYOND THE CURRENT HWO PERIOD...HAVE KEPT THE MENTION OF THE
STORM TO THIS DISCUSSION ONLY. HOWEVER...IF TRENDS ON THIS SYSTEM
CONTINUE...LATER SHIFTS WILL NEED TO MENTION THE STORM IN THE HWO
AND IN OTHER DECISION SUPPORT SERVICES.
&&
.AVIATION...TONIGHT AND FRIDAY
535 PM CST THU FEB 14 2013
THE MAIN FOCUS AT THE TAF SITES TONIGHT INTO TOMORROW IS WITH
CEILINGS AND WHEN THEY MAY BE AT MVFR. CURRENTLY...THE BACK EDGE
OF THE LOWER CLOUDS IS TRACKING TO THE SOUTHEAST ALONG THE
MISSISSIPPI RIVER AND SHOULD BE INTO RST AROUND 1Z AND LSE BETWEEN
2/3Z. AFTER THIS MOVES IN THERE WILL JUST BE SOME HIGH LEVEL CLOUD
COVER TO CONTEND WITH UNTIL THE NEXT SYSTEM DIVES DOWN FROM SOUTH
CENTRAL CANADA. SKIES SHOULD CLEAR OUT OVERNIGHT WITH THE NEXT
BATCH OF CLOUDS COMING IN TOMORROW MORNING WHICH COULD BE MVFR AT
2-3KFT. NOT A LOT OF LIFT WITH THIS FEATURE...BUT THERE COULD BE A
FEW FLURRIES THAT OCCUR...BUT NOT STRONG ENOUGH TO CAUSE ANY
VISIBILITY DROPS. WINDS WILL STAY PERSISTENT OUT OF THE NORTHWEST
AT 8-15KTS THROUGH THE NEXT 24 HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
237 PM CST THU FEB 14 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1032 PM MST THU FEB 14 2013
.UPDATE...
ISSUED AT 546 PM MST THU FEB 14 2013
ADJUSTED POPS TO REDUCE COVERAGE OF SNOW ACROSS THE SOUTHEAST MTS/PLAINS.
GREATEST COVERAGE FOR THE NEXT COUPLE HOURS WILL BE ACROSS THE
LOWER EASTERN SLOPES OF THE SANGRES/WETS AND SRN I-25 CORRIDOR.
TREND WILL BE FOR WINDS TO SHIFT OUT OF THE SOUTHEAST WITH SOME
ISOLATED TO SCATTERED SNOW SHOWERS POSSIBLE ACROSS PORTIONS OF
SOUTHERN EL PASO COUNTY. DOESN`T APPEAR SNOWFALL WILL AMOUNT TO
MUCH WITH MOST AMOUNTS STAYING WELL UNDER 1 INCH. LATEST HIGH RES
MODELS REALLY DIMINISH PCPN QUICKLY TOWARDS 06Z. CURRENT GRIDS
ALREADY HAD THIS TREND WELL DEPICTED SO MAIN CHANGE WAS TO THE
FIRST 3 HOURS. -KT
&&
.SHORT TERM...(TONIGHT AND TOMORROW)
ISSUED AT 308 PM MST THU FEB 14 2013
A FAST MOVING COLD FRONT HAS MOVED SOUTH OF HIGHWAY 50. THE FRONT
SHOULD CLEAR THE CO/NM BORDER BY 22Z. THE HRRR AND RAP PROG ANY
LINGERING SNOW SHOWERS TO END BY MIDNIGHT ACROSS THE AREA.
HOWEVER...THE NAM12 AND GFS ARE HOLDING ON TO SNOW SHOWERS
THROUGH 12Z ACROSS THE SOUTHERN I-25 CORRIDOR. DECIDED TO LEAVE
SOME 15 TO 35 POPS SOUTH AND WEST OF TAD IN THE GRIDS. DUE TO TO
THE FAST MOVEMENT OF THE FRONT/PRECIP...LITTLE TO NO ACCUMULATIONS
ARE EXPECTED UNDER ANY OF THE SNOW SHOWERS EAST OF THE CONTINENTAL
DIVIDE. GUSTY NORTHEAST WINDS WILL BEGIN TO RELAX AFTER 02Z. WEST
OF THE I-25 CORRIDOR...LIGHT SNOW SHOWERS WILL CONTINUE IN AND
AROUND THE LEADVILLE AREA OVERNIGHT INTO TOMORROW MORNING. THE
SAN LUIS VALLEY WILL BE MOSTLY CLEAR...COLD...AND DRY OVERNIGHT
FRIDAY...MODELS CONTINUE TO SHOW LIGHT SNOW SHOWERS IN THE LEADVILLE
AREA THROUGH FRIDAY AFTERNOON AND HAVE KEPT POPS IN PLACE AS PREVIOUSLY
FORECASTED. 700MB TEMPERATURES WILL FALLING TO -11 TO -13.5C WILL
KEEP HIGH TEMPERATURES 3-5 DEGREES COOLER ACROSS MOST LOCATIONS
FRIDAY AFTERNOON. A FEW LINGERING CLOUDS ACROSS THE AREA WILL ALSO
HELP TO CAP HIGH TEMPERATURES TOMORROW AFTERNOON. -PJC
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 308 PM MST THU FEB 14 2013
(FRIDAY NIGHT-THURSDAY)
FRIDAY NIGHT-SUNDAY...STRONG NORTH TO NORTHWEST FLOW ALOFT ACROSS
THE REGION FRIDAY NIGHT MODERATES AND BECOMES MORE WESTERLY THROUGH
THE DAY SUNDAY AS UPPER LEVEL RIDGING BUILDING ACROSS THE GREAT
BASIN FLATTENS ACROSS THE STATE AHEAD OF MORE SHORT WAVE ENERGY
MOVING ONSHORE ACROSS THE PAC NORTHWEST COAST. DRY WEATHER WITH WELL
ABOVE SEASONAL TEMPERATURES EXPECTED THROUGH THE FIRST PART OF THE
HOLIDAY WEEKEND...WITH BREEZY WEST WINDS ACROSS THE HIGHER TERRAIN
AND IMMEDIATE ADJACENT PLAINS SATURDAY AND SATURDAY NIGHT. SHOULD
SEE INCREASING HIGH CLOUDS FROM WEST TO EAST THROUGH THE DAY SUNDAY
AS THE SYSTEM CONTINUES TO MOVE ACROSS THE GREAT BASIN.
SUNDAY NIGHT-MONDAY NIGHT...STILL SOME MODEL DIFFERENCES ON AMPLITUDE
OF GREAT BASIN SYSTEM MOVING ACROSS THE ROCKIES WITH THE 12Z GFS
STILL DIGGING FURTHER SOUTH THAN THE ECMWF...HOWEVER THE GFS HAS
STARTED TO TREND FURTHER NORTH AND IS WEAKER WITH THE SYSTEM THAN
PREVIOUS RUNS. WITH THAT SAID...SHOULD STILL SEE A HEALTHY COLD
FRONT WITH A 10-20 DEGREE DROP IN TEMPERATURES FROM SUNDAY...MOST
NOTICEABLE ACROSS EASTERN COLORADO. HAVE ALSO KEPT ISOLATED TO
SCATTERED POPS INTACT ACROSS THE HIGHER TERRAIN AND IMMEDIATE
ADJACENT PLAINS...WITH NOT MUCH PRECIPITATION EXPECTED...ESPECIALLY
IF THE SYSTEM CONTINUES TO TREND FURTHER NORTH.
TUESDAY-THURSDAY...WARMER WESTERLY FLOW PROGGED ACROSS THE AREA
TUESDAY WITH INCREASING SOUTHWEST FLOW TUESDAY NIGHT AND WEDNESDAY
AHEAD OF A STRONGER SYSTEM MOVING INTO THE GREAT BASIN. SOME
DIFFERENCES IN MOVEMENT OF THIS SYSTEM WITH THE GFS LIFTING IT
ACROSS SOUTH CENTRAL COLORADO WEDNESDAY NIGHT AND INTO THE NORTHWEST
KANSAS ON THURSDAY. THE LATEST EC IS A TAD FURTHER SOUTH WITH THE
SYSTEM ACROSS SOUTHWEST KANSAS ON THURSDAY...WHICH PRODUCES BETTER
CHANCES OF SNOW AND BLOWING SNOW ACROSS THE SOUTHEAST PLAINS NORTH
OF HIGHWAY 50...ESPECIALLY AREAS ALONG THE PALMER DVD. AT ANY
RATE...MODEL CONSENSUS IS FAIRLY CONSERVATIVE THIS FAR OUT AND
HAVE INCREASED POPS TO CHANCES ALONG THE CONTDVD FOR THE WEDNESDAY
THROUGH EARLY THURSDAY PERIODS. HAVE ALSO INCREASED POPS TO SLIGHT
CHANCES ACROSS PORTIONS OF THE PLAINS. THIS SYSTEM WILL LIKELY
PRODUCE SIGNIFICANT WEATHER SOMEWHERE ACROSS THE REGION...THOUGH
TIME WILL TELL AS TO EXACTLY WHERE. -MW
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1027 PM MST THU FEB 14 2013
VFR CONDITIONS TO CONTINUE FOR KPUB AND KALS OVER THE NEXT 24 HRS.
FOR KCOS AND MUCH OF EL PASO COUNTY AND THE PALMER DVD...VERY
ISOLATED SNOW AND MVFR CLOUD DECK IS EXPECTED TO PERSIST FOR MUCH
OF THE NIGHT THROUGH 14Z TOMORROW MORNING BEFORE BREAKING UP.
BRISK N-NW SFC WINDS WILL REDEVELOP BETWEEN 16Z AND 18Z MOST
LOCATIONS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TORGERSON
SHORT TERM...PJC
LONG TERM...MW
AVIATION...MOORE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1143 PM CST THU FEB 14 2013
.SHORT TERM /TONIGHT/...
FORECAST CONCERN IS FOCUSED ON QUICK MOVING SHORTWAVE TO BRING SOME
LIGHT PRECIP TO THE FORECAST AREA THROUGH THIS EVENING. WEAK BROAD
FORCING ALONG THE COLD FRONT WILL BRING LIGHT SNOW OR RAIN THROUGH
THE LATE AFTERNOON BEFORE SWITCHING OVER TO ALL SNOW AFTER 00Z
FRIDAY. BUFR SOUNDINGS SHOWING BRIEF WINDOW OF FAIRLY DEEP
SATURATION FROM 21Z OR CURRENTLY THROUGH 03Z FRIDAY. COLUMN LOSES
ICE INTRODUCTION AND FORCING ACROSS NORTHERN IOWA B/T 00-03Z.
BELIEVE MODELS ARE BIT SLOW WITH MOVING THIS SYSTEM OUT AND CUT BACK
ON POPS PAST 03Z. 17Z HRRR QUICKLY DIMINISHES PRECIP BY 02Z WHICH
COINCIDES WITH SEVERAL OF THE HIRES WRF MODELS AND NAM12. ALSO
DECREASED SNOW AMOUNTS WITH THE QUICKER MOVEMENT...WEAKER FORCING
AND LESS MOISTURE AVAILABLE.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
COLD AIR SETTLING INTO THE REGION BY 12Z FRIDAY WITH GENERALLY A
CLOUDY DAY IN STORE. LINGERING FLURRIES WILL BE POSSIBLE FRIDAY WITH
WEAK WAVE PASSING THROUGH THE REGION DURING THE DAYTIME HOURS.
OTHERWISE TEMPERATURES WILL CREEP BACK UP DURING THE DAY TO NEAR 20
NORTH AND THE LOWER 30S IN THE SOUTH. AS HIGH BUILDS SOUTH FRIDAY
NIGHT SKIES WILL CLEAR OUT AND COLDER NIGHT IN STORE. LOWS WILL DROP
OFF INTO THE SINGLE DIGITS NORTH WITH THE TEENS IN THE SOUTHEAST.
H850 TEMPS REMAIN RATHER COLD THROUGH THE EARLY PART OF THE FORECAST
BUT AS THE RIDGE AXIS SLIPS EAST SATURDAY EVENING...TEMPS WARM
OVERNIGHT INTO SUNDAY MORNING. WARM AIR ADVECTION WILL INITIATE
CLOUDS WITH GENERALLY LIGHT FLOW OVERNIGHT. BY SUNDAY MED RANGE
MODELS CONTINUE WITH PREVIOUS RUNS TO SHOW DECENT WARM UP BY LATE
DAY. H850 TEMPS WARM TO NEAR 0C NORTHEAST AND TO NEAR 4-5C SOUTHWEST
AND WEST BY 00Z. THIS BODES WELL FOR TRENDS OF HIGHS IN THE 50S
ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA WITH HIGHS ABOVE
THE FREEZING MARK IN THE NORTHEAST. AS THE NEXT UPSTREAM WAVE
APPROACHES THE AREA ANOTHER STRONG COLD FRONT WILL PASS SOUTHEAST
THROUGH IOWA ON MONDAY. LIFT ASSOCIATED WITH IT WILL ALLOW FOR A
RAIN OR RAIN/SNOW MIXTURE TO OCCUR SOUTHEAST BY LATE IN THE
AFTERNOON. ANOTHER STRETCH OF COLDER THAN NORMAL WEATHER IS
ANTICIPATED FOR THE EARLY PORTION OF NEXT WEEK WITH A SLOW
MODERATION TOWARD THURSDAY...BUT STILL BELOW THE FREEZING MARK. MED
RANGE MODELS STILL PAINT AN ACTIVE STORM OVER THE FORECAST AREA BY
LATE WED OR EARLY THURSDAY WITH THE MAIN PORTION OF THE STORM TO HIT
THURSDAY THROUGH FRIDAY. SIGNATURE HAS SHOWN UP FOR TWO DAYS NOW IN
MOST MED RANGE MODELS...BUT EVEN SO...AT SEVEN DAYS OUT THERE ARE
STILL TO BE MANY CHANGES IN THE TRACK AND DETAILS. AT THIS TIME WILL
EMPHASIZE ONLY A STRONGER SYSTEM OVER THE CENTRAL STATES LOOKS MORE
LIKELY BUT WAY TOO EARLY TO BECOME OVERLY EXCITED ABOUT MODEL
DETAILS...ESPECIALLY GIVEN THAT THE 12Z GFS IS ABOUT 10 MB STRONGER
THAN THE 12Z EURO MODEL TODAY.
&&
.AVIATION...15/06Z
CLOUDS AND COLD FRONT HAVE MOVED SOUTH OF IA AND WINDS WILL DIMINISH
EARLY IN THE TAF PERIOD. ANOTHER SHORT WAVE WILL DROP SOUTHEAST
ACROSS IA ON FRI BRINGING WITH IT LOCAL MVFR/IFR CONDITIONS IN CIG
AND -SHSN TO THE NORTHERN TAF SITES. EXPECT THE SRN SITES TO REMAIN
VFR WITH ISOLATED -SHSN DURING THE DAY. CLEARING OVERSPREADING THE
STATE FRI EVE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...MS FEB 13
LONG TERM...REV
AVIATION...MS FEB 13
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1142 PM CST THU FEB 14 2013
.AVIATION...
A FAST MOVING UPPER LEVEL DISTURBANCE IN NORTHERN ILLINOIS IS
MOVING EAST BRINGING CLEARING SKIES. NORTHWEST WINDS OF 10 TO 20
KTS WILL GRADUALLY LOWER TO AROUND 10 TO 15 KTS ON FRIDAY AS
CANADIAN HIGH PRESSURE MOVES IN FROM THE DAKOTAS.
NICHOLS
&&
.PREV DISCUSSION... /ISSUED 320 PM CST THU FEB 14 2013/
SYNOPSIS...
18Z SURFACE ANALYSIS INDICATED LOW PRESSURE OVER NORTHERN LOWER MI
WITH A TROUGH OR WEAK COLD FRONT REACHING SOUTH-SOUTHWEST ACROSS
IL...MO INTO EASTERN OK. A SECOND REINFORCING COLD FRONT EXTENDED
WEST FROM THE LOW ACROSS WI TO ALONG THE IA/MN BORDER. SOUTH OF THIS
FRONT...TEMPERATURES WERE IN THE 30S TO LOWER 40S WITH BRISK W-NW
WINDS ACROSS THE FORECAST AREA. ALOFT...A BROAD CYCLONIC FLOW
ENCOMPASSED THE EASTERN 2/3RDS OF THE CONTINENTAL U.S. THERE WERE A
SERIES OF SHORTWAVES EMBEDDED IN THIS FLOW FROM THE GREAT LAKES TO
THE CANADIAN ROCKIES. THE FOCUS IN THE SHORT TERM IS A VORT MAX
EVIDENT ON SATELLITE WV IMAGES OVER N CENTRAL IA...WHERE AREA RADARS
AND SURFACE REPORTS WERE INDICATING SNOW SHOWERS.
SHORT TERM...TONIGHT AND FRIDAY...
MAIN FOCUS IS ON THE SNOW SHOWERS THAT WILL OVERSPREAD THE AREA
LATE THIS AFTERNOON AND EVENING...THEN COOLER TEMPERATURES AND
POTENTIAL FLURRIES THROUGH FRIDAY.
AN AXIS OF ROTATION SEEN IN RECENT KDMX 88D LOOPS INDICATED THE
UPSTREAM VORT MAX WAS CENTERED ROUGHLY NORTH OF WEBSTER CITY AT 20Z.
THIS WAS WELL SOUTH OF THE OPERATIONAL NAM...GFS AND ECMWF TRACKS
FROM THIS MORNING. THE RECENT RAP RUNS APPEARED TO HAVE A DECENT
CAPTURE OF THIS VORT CENTER AND WILL FOLLOW ITS OVERALL
SOUTHEASTWARD TRACK. THIS WILL SEND THE UPSTREAM SNOW SHOWERS...
TRENDING HEAVIEST ALONG AND NORTH OF THE VORT MAX...SOUTHEAST
THROUGH THE EAST CENTRAL IA AND THEN W CENTRAL IL OVER THE NEXT
SEVERAL HOURS. COLD ADVECTION ALOFT WAS SHOWN LEADING TO STEEP MID
LEVEL LAPSE RATES ON THE ORDER OF 7 TO 8 DEG C/KM IN THIS MORNING/S
MODEL RUNS. THIS...COMBINED WITH THE UPPER LEVEL FORCING AND LIFT
ALONG THE SOUTHWARD MOVING COLD FRONT WILL SUPPORT CONTINUED LIGHT
TO MODERATE SNOW SHOWERS AND AT LEAST LIGHT ACCUMULATIONS. THE HIGH
RES RAP CONTINUES TO INDICATE QPF VALUES IN THE RANGE OF .2 TO .3
INCHES AS SNOW SHOWERS TRACK FROM ABOUT CID THROUGH THE QUAD CITIES
TO NEAR KEWANEE BETWEEN 23Z AND 05Z AND HAVE LIKELY POPS ALONG THIS
AXIS. WHILE THIS LOOKS OVERDONE BASED ON MEAGER PRECIPITATION
AMOUNTS REPORTED SO FAR AT AUTOMATED UPSTREAM SITES...CANNOT RULE
OUT BANDS OF 1 TO POSSIBLY 2 INCH SNOW ACCUMULATIONS IF THE
CONVECTION TAPS INTO THE DEEPER INSTABILITY OVER THE NEXT SEVERAL
HOURS. BASED ON THE INITIAL WARM LOW LEVELS AND TEMPERATURES IN
THE 30S TO LOWER 40S LEADING TO A RAIN/SNOW MIX AT ONSET...WILL
STAY CLOSE TO A MORE CONSERVATIVE .5 TO 1 INCH SNOWFALL RANGE FOR
NOW AND WATCH TRENDS CLOSELY.
THE CURRENT PACE OF THE VORT MAX SHOULD SEND THE SHOWERS EAST OF THE
AREA BY MID EVENING...AND HAVE ONLY SLIGHT CHANCE POPS AFTER
MIDNIGHT IN THE EAST AND SOUTHEAST. THE COLD FRONT SHOULD SLIDE
THROUGH THE ENTIRE AREA BY MIDNIGHT...FOLLOWED BY PARTIAL CLEARING
BASED ON SATELLITE TRENDS. GUIDANCE LOWS BY SUNRISE IN THE MID TEENS
NORTH TO MID 20S SOUTH LOOK REASONABLE.
FRIDAY...WILL KEEP A MENTION OF SCATTERED FLURRIES GOING IN THE
FORECAST BASED ON THE STREAM OF WEAK IMPULSES AND MID LEVEL MOISTURE
IN THE CYCLONIC FLOW ALOFT. CLOUD COVER AND COLD AIR ADVECTION
SHOULD LIMIT THE DIURNAL TEMPERATURE RISE. HAVE STAYED CLOSE TO
THE PREVIOUS FORECAST AND LATEST MODEL GUIDANCE WITH HIGHS
RANGING FROM THE LOWER 20S NORTH TO LOWER 30S SOUTH.
SHEETS
LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY
FRIDAY NIGHT AND SATURDAY WE REMAIN IN THE NORTHWEST CYCLONIC FLOW
AND STEEP MID LEVEL LAPSE RATES WITH ENOUGH LOW LEVEL MOISTURE TO
ALLOW FOR FLURRIES DURING THE OVERNIGHT AND SATURDAY MORNING. WE
ALSO HAVE SOME UPPER LEVEL VORT MAXES THAT SHOULD ALSO HELP TO
TRIGGER THESE FLURRIES. THERE IS NOT REALLY ENOUGH MOISTURE FOR MORE
THAN THAT...THOUGH A DUSTING IS POSSIBLE IF REPEAT ACTIVITY AFFECTS
THE SAME AREA. TEMPERATURES TO REMAIN COLD THROUGH SATURDAY WITH
HIGHS SATURDAY IN THE 20S TO AROUND 30. WARMED MINS FRIDAY NIGHT DUE
TO THE EXTRA CLOUD COVER AND RANGE FROM 10-20.
STRONG WARM AIR ADVECTION SETS IN OVER THE AREA AT 850MB SATURDAY
NIGHT AND SUNDAY. THIS IS LIKELY TO BRING ANOTHER BAND OF CLOUD
COVER ACROSS THE AREA OVERNIGHT AND SUNDAY MORNING. SATURDAY NIGHT
MINS ARE LIKELY TO NOT SHOW MUCH CHANGE YET AS MOST OF THE WARMING
IS ALOFT. SUNDAY HOWEVER WE ARE LIKELY TO SEE A BIG WARM-UP WITH
HIGHS IN THE MID 30S NORTHEAST TO THE UPPER 40S SOUTHWEST.
TEMPERATURES APPROACHING 50 ARE POSSIBLE IF WE CAN CLEAR OUT AND MIX
DEEPLY ENOUGH.
THE NEXT PUZZLE OF THE DAY IS MONDAY AND MONDAY NIGHT AS OUR NEXT
STRONG STORM SYSTEM CROSSES THE MIDWEST. A RELATIVELY SHALLOW
LONGWAVE TROUGH MOVES ACROSS THE AREA WITH TWO SEPARATE PIECES OF
ENERGY...ONE FARTHER NORTH THAT GENERATES A SURFACE LOW OVER
SOUTHERN MINNESOTA BY MONDAY MORNING. ANOTHER PIECE OF ENERGY IS
OVER NEW MEXICO WHICH GENERATES A SURFACE LOW OVER OKLAHOMA AT THE
SAME TIME. THIS SYSTEM SWEEPS OUT ACROSS THE MIDWEST MONDAY AND
MONDAY NIGHT. MODELS HAVE BEEN VARYING ON HOW WELL PHASED THESE
SYSTEMS WILL BE OVER THE PAST COUPLE DAYS AS WELL AS HOW MUCH ENERGY
WILL BE WITH EACH. THUS...THE IMPACT FOR OUR CWA HAS VARIED FROM
DRY TO A RAIN/SNOW MIX. FOR NOW MODELS ARE COMING IN A LITTLE
SLOWER AND STRONGER...AND ARE BRINGING MORE MOISTURE AND WARMTH INTO
THE AREA. THUS...HAVE RAISED POPS THROUGH THE PERIOD. ALSO...HAVE
CONVERTED MONDAY TO NEARLY ALL RAIN...WITH JUST A RAIN SNOW MIX
ACROSS THE NORTH. MONDAY NIGHT WE GRADUALLY SWITCH TO ALL
SNOW...BUT THE TIMING IS STILL VERY MUCH UP IN THE AIR. DUE TO THE
START BEING ALL RAIN...SNOWFALL AMOUNTS WILL BE LIGHT.
TUESDAY AND WEDNESDAY ARE RELATIVELY QUIET WITH A STRONG SURFACE
RIDGE BUILDING INTO THE AREA FOR DRY AND COLD CONDITIONS. IN
FACT...IF WE CAN GET DECENT RADIATIONAL CONDITIONS FOR TUESDAY NIGHT
MIN TEMPS COULD DIP INTO THE SINGLE DIGITS OVER A FAIRLY LARGE
PORTION OF THE AREA. HOWEVER...THIS IS STILL SOMEWHAT QUESTIONABLE
AND HAVE STAYED A LITTLE WARMER FOR NOW.
THE BIG QUESTION OF THE FORECAST COMES THURSDAY. FOR SEVERAL MODEL
RUNS NOW...THE ECMWF AND GFS HAVE BEEN ADVERTISING A VERY STRONG
STORM FOR THE MIDWEST ON THURSDAY AND FRIDAY. THERE IS REMARKABLE
CONSISTENCY AND CONFIDENCE IS GROWING THAT SOMEWHERE IN THE MIDWEST
THERE WILL BE A MAJOR WINTER STORM...IF NOT A BLIZZARD.
HOWEVER...WHETHER OUR AREA WILL BE AFFECTED OR NOT IS VERY MUCH IN
QUESTION. WE CURRENTLY HAVE DIFFERING MODEL SOLUTIONS...ONE OF WHICH
DEPICTS THE WINTER STORM AFFECTING THE CWA WITH MAJOR SNOW
ACCUMULATIONS...ANOTHER WHICH BRINGS IN MORE WARM AIR AND AFFECTS US
WITH ANOTHER RAIN/SNOW MIX EVENT WITH LESSER ACCUMULATIONS. IN
GENERAL PREFER THE MORE CONSISTENT AND BETTER VERIFYING ECMWF WHICH
HAS THE LARGER SNOW ACCUMULATIONS...BUT CANNOT TOTALLY DISCOUNT THE
WARMER GFS EITHER. WE WILL HAVE TO WATCH THIS STORM VERY CAREFULLY
OVER THE NEXT SEVERAL DAYS TO MONITOR THESE TRENDS. YOU WILL
DEFINITELY WANT TO KEEP UP WITH THE LATEST INFORMATION REGARDING
THIS WINTER STORM SYSTEM. FOR NOW THE LATEST FORECAST REFLECTS A
BLENDED APPROACH...AND WE WILL HAVE TO REFINE WITH LATER FORECASTS.
LE
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
NICHOLS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1148 PM EST THU FEB 14 2013
.AVIATION...
//DISCUSSION...
AREA OF LIGHT SNOW WITH CLIPPER WILL EXIT EAST OF KMBS/KFNT AS THE
FORECAST PERIOD BEGINS. FURTHER SOUTH...BAND OF LAKE EFFECT SNOW
SHOWERS WILL AFFECT THE I-94 CORRIDOR FOR A FEW HOURS EARLY IN THE
FORECAST BEFORE SHIFTING SOUTH. OTHERWISE...BKN-OVC MVFR CIGS WILL
BE COMMON THROUGHOUT THE FORECAST PERIOD...AVERAGING 1500-2500 THRU
10Z TO 12Z AND 2500-3500 ON FRIDAY.
FOR DTW...CIGS WILL BOUNCE GENERALLY BETWEEN 2-3KFT OVERNIGHT WITH A
FEW SNOW SHOWERS EARLY AS LAKE EFFECT BAND BRUSHES THE AREA. CIGS
WILL RISE CLOSER TO 3500 FEET ON FRIDAY AS COLD...CYCLONIC NORTHWEST
FLOW PERSISTS...WITH A BETTER CHANCE FOR SNOW SHOWERS LATE FRIDAY
NIGHT AS NEXT SHORTWAVE IMPULSE ROTATES SOUTHEAST INTO THE REGION.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING HEIGHTS BELOW 5000 FEET THROUGHOUT MUCH
IF NOT ALL OF THE TAF PERIOD.
&&
.PREV DISCUSSION...ISSUED 359 PM EST THU FEB 14 2013
SHORT TERM...THIS EVENING AND TONIGHT
THE VORTICITY RICH POTENTIAL VORTICITY ANOMALY NOW SPINNING ACROSS
CENTRAL LAKE MICHIGAN HAS LED TO A NUMBER OF SPOKES/BANDS OF
PRECIPITATION SLIDING THROUGH LOWER MICHIGAN. SINCE MIDDAY THESE
BANDS HAVE BEEN NOTHING MORE THAN LIGHT RAIN SHOWERS OR SPRINKLES
PER SFC REPORTS AND A NEAR SURFACE MELTING LAYER AT GREATER THAN 4C.
VARIOUS HIRES MODELS ARE SUGGESTING THAT CONVECTION/SHOWER
DEVELOPMENT WILL TAKE PLACE ALONG AND AHEAD OF THE COLD FRONT
BETWEEN 21-00Z. THIS IDEA REMAINS VALID. DIFFICULT TO EVALUATE THE
OVERALL THERMODYNAMIC PROFILE OR HOW MUCH CAPE IS OUT THERE WITH THE
VALID RUC BASED SPC MESOANALYSIS GRAPHIC SHOWING NOTHING IN THE WAY
OF MUCAPE. GOING THROUGH MODEL DATA THOUGH SUGGESTS THAT 50 TO 100
J/KG IS PLAUSIBLE GIVEN SFC/DWPT VALUES THAT ARE ON TARGET.
EVOLUTION OF MODEL SOUNDINGS SUGGESTS THAT IT WILL REQUIRE SOME
COOLING FROM APPROACHING COLD FRONT TO ERODE A LOW CAPPING LAYER TO
ALLOW FOR INITIATION. THE POTENTIAL EXISTS FOR CONVECTION TO YIELD
GRAUPEL/ICE PELLETS. ADDITIONALLY...THERE REMAINS A POSSIBILITY THAT
BURSTS COULD PRODUCE MORE IN THE WAY OF SNOW...AND THE PERCENTAGE OF
OCCURRENCE IS AN UNKNOWN. FARTHER NORTH...EXPECTING THE ACTIVITY TO
FALL AS RAIN...ALTHOUGH THIS AREAS STANDS A BETTER CHANCE TO SEE
SOME LIGHT SNOW WITH MINOR ACCUMULATIONS. WINDS WILL INCREASE...UP
TO 25 TO 30 MPH...AS WIND DIRECTIONS SHIFT FROM 200 TO 240 POST COLD
FRONT.
ISENTROPIC DOWNGLIDE WILL COMMENCE BETWEEN 00-03Z...KICKING IT UP A
COUPLE OF GEARS BETWEEN 03-09Z. THE COLUMN IS SHOWN TO BECOME QUITE
STABLE IN THE 900-700MB LAYER...TOO STABLE TO SUPPORT MUCH IN THE
WAY OF SNOW TONIGHT. NAM IS HIGHLIGHTING SOME LAKE EFFECT
BANDING/ENHANCED CONVERGENCE ACROSS SW LOWER LATE TONIGHT. DID LEAVE
A LOW CHANCE FOR LIGHT IN ACROSS THE SOUTH AS THERE IS SOME
POTENTIAL FOR SOME SNOWFLAKES TO MAKE THE TRIP ACROSS THE PENINSULA.
OTHERWISE...FLURRIES FOR A MAJORITY OF THE AREA. LOWS TONIGHT WERE
DERIVED FROM A BLEND OF RAW MODEL OUTPUT...A DECENT ADJUSTMENT
DOWNWARD UPPER TEENS NORTH TO UPPER 20S SOUTH.
LONG TERM...FRIDAY THROUGH NEXT THURSDAY
LONGWAVE TROUGH WILL LOCK COOL AIR IN PLACE OVER THE GREAT LAKES
THROUGH THE WEEKEND...AS H850 TEMPS DROP TO AROUND -18C (BY SAT
NIGHT) IN THE POST-FRONTAL AIRMASS. CHANCES FOR ACCUMULATING SNOW
LOOK FAIRLY LOW FOR THIS SIDE OF THE STATE...AND WILL BE DUE TO A
COMBINATION OF WEAK SHORTWAVES AND LAKE EFFECT. SHORTWAVES MAY BE A
LITTLE HARD TO TIME DUE TO SMALL NATURE AND LACK OF SAMPLING (AT
THIS TIME) AND FORECAST ADJUSTMENTS ARE STILL POSSIBLE AS CHANGES IN
TIMING/LOCATION OF SHORTWAVES IMPACT LAKE EFFECT PARAMETERS SUCH AS
STABILITY...MOISTURE...AND WIND SPEED AND TRAJECTORY.
MODEL GUIDANCE TAKES THE WAVE NOW DROPPING THROUGH SOUTHERN MANITOBA
ACROSS NORTHERN LOWER MICHIGAN TOMORROW...WHILE ALSO SHEARING APART
ANOTHER SHORTWAVE AS IT DROPS FROM THE DAKOTAS DOWN INTO THE OHIO
VALLEY. VERY WEAK LIFT ASSOCIATED WITH THESE WAVES COULD PROVIDE A
BRIEF SNOW SHOWER TO THE AREA...BUT MAINLY EXPECT A LOT OF CLOUDS
AND FLURRIES AROUND DUE TO LAKE EFFECT AND STEEP LAPSE RATES. DID
KEEP LOW POPS IN THE FORECAST...BUT THINK FAIRLY WEAK FLOW OVER THE
LAKE AND ONLY MODERATE INSTABILITY SHOULD KEEP ACCUMULATIONS TO OUR
WEST. SIMILAR POP FORECAST EXISTS ON FRIDAY NIGHT. ALTHOUGH MOISTURE
DEPTH AND COLD AIR ADVECTION WILL INCREASE...MEAN SURFACE-850MB FLOW
ACROSS LAKE MICHIGAN WILL ONLY RUN 10-15 KNOTS...AND WILL TURN A
LITTLE MORE TO THE NORTHWEST. AGAIN WOULD EXPECT MOSTLY
FLURRIES...AND ONLY LOW CHANCES FOR LIGHT ACCUMULATIONS SOUTH OF A
LINE FROM HOWELL TO DETROIT.
POTENTIAL FOR LIGHT SNOW LOOKS A LITTLE BETTER ON SATURDAY AS A
SHORTWAVE TROUGH AXIS CLIPS ACROSS THE AREA. LAKE EFFECT ENHANCEMENT
ALSO LOOKS MORE LIKELY AS EQUILIBRIUM HEIGHTS OVER LAKE
MICHIGAN HIT THEIR PEAK AROUND 12KFT AND LAKE TO H850 DELTA T VALUES
RISE TO OVER 20 C. LIMITING FACTORS FOR THIS SIDE OF THE STATE ONCE
AGAIN WILL BE LIGHT FLOW AND WINDS TURNING MORE TO THE
NORTH-NORTHWEST. WOULD EXPECT FLURRIES AND SCATTERED LIGHT SNOW
SHOWERS ACROSS THE AREA IN THIS SET-UP...WITH BETTER POTENTIAL
(HIGHER POPS) SOUTH OF M-59 WHERE CONVERGENCE SHOULD BE BETTER.
LONGWAVE TROUGH WILL PUSH TO THE EAST COAST DURING THE SECOND HALF
OF THE WEEKEND...ALLOWING AN UPSTREAM RIDGE TO SLIDE IN OVERHEAD
SUNDAY INTO MONDAY. ENERGY DIVING OUT OF THE GULF OF ALASKA WILL
DROP THROUGH THE CENTRAL ROCKIES MONDAY...PULLING ADDITIONAL ENERGY
OUT OF THE SOUTHERN STREAM BEFORE IT BECOMES MORE ORGANIZED AND
DEEPENS OVER THE GREAT LAKES MONDAY NIGHT AND TUESDAY (AIDED BY GOOD
HEIGHT FALLS AND STRONG JET DYNAMICS). TRENDS WITH THE EURO AND GFS
HAVE BEEN TO SHIFT THIS SYSTEM FURTHER NORTH OVER THE PAST 24
HOURS...WITH A SURFACE LOW CENTER TRACK MORE ACROSS CENTRAL OR
NORTHERN MICHIGAN. GIVEN THAT THE GEM AND UKMET ARE STILL FURTHER
SOUTH WITH THE TRACK...MADE JUST MINOR ADJUSTMENTS TO PRECIPITATION
TYPE THIS FORECAST CYCLE TO INCREASE RAIN POTENTIAL. 14.12Z EURO/GFS
SOLUTIONS NOW SUPPORT ALL RAIN MONDAY NIGHT BEFORE A CHANGEOVER TO
SNOW BEHIND A STRONG COLD FRONT ON TUESDAY. ACCUMULATIONS STILL LOOK
POSSIBLE...BUT MAY BE DELAYED UNTIL TUESDAY.
MARINE...
LOW PRESSURE WILL TRACK THROUGH LOWER MICHIGAN THIS AFTERNOON AND
ACROSS NORTHERN LAKE HURON THIS EVENING. CURRENT SURFACE
OBSERVATIONS IN THE INCREASED GRADIENT PORTION OF THE SURFACE LOW IS
SUPPORTING WIND GUSTS OF UP TO 30 KNOTS. WITH NO EXPECTED
DEEPENING/ACTUAL MIDLEVEL WEAKENING RATES WILL CANCEL THE GALE WATCH
AND FORGO A GALE WARNING. THIS IS ALSO SUPPORTED BY THE VERY BRIEF
DURATION TIME. HOWEVER...WITH THE COLD NORTHWEST FLOW FOLLOWING THE
CYCLONE...DID ISSUE A BRISK WIND ADVISORY FOR ALL NEARSHORE ZONES.
WINDS WILL WEAKEN ON FRIDAY AS ARCTIC HIGH PRESSURE BUILDS INTO THE
WESTERN GREAT LAKES REGION. THIS HIGH WILL KEEP RELATIVELY LIGHT
WINDS ON THE LAKES THROUGH THE WEEKEND. A LOW PRESSURE SYSTEM IS
FORECAST TO INTENSIFY OVER THE GREAT LAKES REGION MONDAY NIGHT INTO
TUESDAY AND WILL OFFER THE NEXT CHANCE FOR STRONG WINDS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
BRISK WIND ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING SAGINAW BAY...UNTIL 10 AM FRIDAY.
LAKE ST CLAIR...
BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY.
MI WATERS OF LAKE ERIE...
BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY.
&&
$$
AVIATION.....DG
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
316 AM CST FRI FEB 15 2013
.SHORT TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TODAY)
EARLY MORNING RUC ANALYSES OF THE 1.5 PVU SFC COMBINED WITH WATER
VAPOR IMAGERY DEPICTED A REASONABLY STRONG PV ANOMALY MOVING ACROSS
NRN MO. THIS FEATURE IS EXPECTED TO CONTINUE MOVING ACROSS THE AREA
TODAY WITHIN A BROADER PATTN OF NW FLOW ALOFT. DESPITE THE PRESENCE
OF A FORCING MECHANISM...THE LIMITING FACTOR FOR MEASURABLE PCPN
TODAY WILL BE MOISTURE GIVEN THE FAIRLY DRY LOW AND MID LEVELS AS
WELL AS DECREASING PW VALUES THROUGH THE DAY. AT THE SFC...A CDFNT
WAS LOCATED FM CENTRAL KS THROUGH NRN MO INTO NRN IL AT 06Z. THIS
FRONT WILL CONTINUE MOVING SEWD TODAY...LEADING TO A COMPLICATED
FCST OF TEMERATURE TRENDS DUE TO THE COMPETING FACTORS OF LOW LEVEL
CAA...POTENTIAL MIXING ABOVE 900 MB...AND THE EFFECTS OF POSTFRONTAL
CLOUDINESS DURING THE LATE MORNING FOLLOWED BY ADDITIONAL CLOUDS
ADVECTING SWD DURING THE LATE AFTN.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TONIGHT THROUGH SUNDAY)
SHORT RANGE MODELS ARE MAINTAINING GOOD RUN TO RUN CONTINUITY
WITH SYNOPTIC FEATURES HEADING INTO THE WEEKEND. ANOTHER SHORTWAVE
WILL DROP SOUTH ACROSS THE PLAINS TONIGHT ON THE BACK SIDE OF THE
UPPER LEVEL TROF...BRINGING A REINFORCING SHOT OF COLD AIR TO THE
AREA FOR SATURDAY. DYNAMICS WITH THIS FEATURE SHOULD CONFINE ANY
PRECIP THREAT TO THE WEST OF OUR CWA...BUT WITH DIRTY NW FLOW AND
MEAN TROF AXIS REMAINING PARKED OVER AREA WE SHOULD CERTAINLY SEE
SOME CLOUDINESS OVERNIGHT AND AT LEAST INTO SATURDAY MORNING.
TEMPERATURE TRENDS IN GOING FORECAST STILL LOOK PRETTY GOOD. THIS
AMS IS FAIRLY CHILLY BUT DUE TO THE EXPECTED CLOUDS OVERNIGHT I HAVE
FOUGHT THE TEMPTATION TO GO TOO COLD...AND STILL HAVE LOWS IN THE
UPPER TEENS TO LOWER 20S. HIGHS SHOULD REBOUND INTO THE L-M30S ON
SATURDAY.
TROF IS STILL ON SCHEDULE TO SWING INTO THE EASTERN U.S. ON SUNDAY.
THIS WILL ALLOW A RAPID TEMPERATURE MODERATION OVER THE CWA...
WITH HIGHS RANGING FROM THE MID 40S OVER OUR E COUNTIES...TO THE
MID 50S OVER MID MO.
(MONDAY-THURSDAY)
ITS PROBABLY A BIT OF AN UNDERSTATEMENT TO SAY THAT THE UA PATTERN
OVER THE CONUS WILL BE ACTIVE FOR MUCH OF NEXT WEEK...WITH THE VERY
AMPLIFIED AND PROGRESSIVE PATTERN PROGGED TO BRING TWO STORM
SYSTEMS INTO THE CENTRAL U.S. MEDIUM RANGE SOLUTIONS ARE
REMAINING IN REMARKABLE RUN TO RUN AND MODEL TO MODEL AGREEMENT
WITH THE TIMING OF THESE SYSTEMS...WITH THE FIRST IMPACTING THE
REGION ON MONDAY AND MONDAY NIGHT AND THE SECOND...AND PROBABLY
STRONGER...SYSTEM ARRIVING LATE WEDNESDAY AND THURSDAY.
MONDAY AND MONDAY NIGHT`S SYSTEM WILL PRIMARILY BE A RAIN
EVENT...WITH THE BULK OF THE PRECIP SHUTTING DOWN ON MONDAY NIGHT
WITH THE ARRIVAL OF THE COLD AIR PREVENTING ANY SIGNIFICANT PERIOD
OF SNOWFALL. SOLUTIONS HAVE NOT BACKED OFF OF THE THINKING THAT
MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM AND DYNAMICS WILL BE
STRONG...SO LIKELY POPS OVER MOST OF THE CWA STILL LOOK LIKE A GOOD
CALL.
ANOTHER SHOT OF COLD AIR IN THE WAKE OF MONDAY`S SYSTEM WILL DROP
TEMPS BACK TO BELOW AVERAGE LEVELS FOR TUESDAY AND WEDNESDAY...AND
THIS COLD AIR WILL SET THE STAGE FOR THE BIG QUESTION MARK FOR
THURSDAY`S SYSTEM...WHICH IS PTYPE. IT CERTAINLY APPEARS THAT THE
FIRST SHOT OF PRECIP INTO THE AREA LATE WEDNESDAY NIGHT AND THURSDAY
MORNING ASSOCIATED WITH INITIAL SURGE OF WARM ADVECTION WILL LIKELY
BE SNOW...BUT PRIMARY QUESTION IS WHAT PTYPES WILL DO DURING THE DAY
ON THURSDAY. OPERATIONAL GFS AND ECMWF ARE BOTH PROGGING VERY
STRONG 850 WAA INTO THE CWA BUT 850 TEMPS...ON BOTH SOLUTIONS...
APPEAR TO BE VERY RELUCTANT TO WARM DURING THE DAY. THIS TREND
LOOKS TO BE TOO COLD GIVEN PLACEMENT OF 850 LOW AND STRENGTH OF
WAA....BUT IT IS PROBABLY A STRONG SIGNAL THAT BOTH MODELS ARE
SUGGESTING THAT THE EVAPORATIVE COOLING THAT DEVELOPS WITH THE
ONSET OF PRECIP WILL BE TOUGH TO OVERCOME.
IF THE CONSENSUS OF THESE SOLUTIONS AND THE LATEST GFS ENSEMBLE
VERIFY...PTYPE WOULD BE ALL SNOW IN THE FAR NORTH AND ALL RAIN IN
THE FAR SOUTH...BUT OVER MOST OF THE CWA PTYPE COULD GO EITHER
WAY. AS MENTIONED BY THE DAY SHIFT YESTERDAY PTYPE FORECASTS WILL
LIKELY BE CHANGING SEVERAL TIMES AS THE EVENT GETS CLOSER IN
TIME...AND SINCE THE STORM IS STILL 7 DAYS OUT WILL MAINTAIN A
BROAD BRUSH APPROACH FOR PTYPE.
TRUETT
&&
.AVIATION...
ISSUED AT 1045 PM CST THU FEB 14 2013
WEAK UPPER LEVEL DISTURBANCE OVER N CNTRL MO WILL DROP SEWD
THROUGH OUR AREA LATE TGT BRINGING LOW-MID LEVEL CLOUD COVER...
POSSIBLY BRIEFLY DOWN TO THE MVFR CATAGORY ALONG WITH A BRIEF
PERIOD OF LIGHT SNOW OR FLURRIES. AT THIS TIME IT LOOKS LIKE THE
LIGHT SNOW WILL BE PATCHY...SO WILL ONLY INCLUDE TEMPO GROUPS FOR
LIGHT SNOW OR FLURRIES IN THE TAFS LATE TGT INTO EARLY FRI MRNG.
ANY LIGHT PRECIPITATION WILL MOVE OUT OF UIN BY 09Z FRI AND THE
REST OF THE TAF SITES EARLY FRI MRNG WHILE THE LOW-MID LEVEL CLOUD
CEILING SCATTERS OUT AS COLD...DRY AIR FILTERS SEWD INTO THE
REGION. NWLY SFC WINDS WILL STRENGTHEN LATE TGT AFTER THE PASSAGE
OF A SECONDARY REINFORCING COLD FRONT. THESE NWLY SFC WINDS WILL
CONTINUE ON FRI AND FRI EVNG.
SPECIFICS FOR KSTL...THE CLOUD CEILING WILL LOWER LATE TGT WITH A
BRIEF PERIOD OF LIGHT SNOW OR FLURRIES POSSIBLE LATE TGT AND
EARLY FRI MRNG. MOST OF THIS SNOW SHOULD BE IN THE FORM OF
FLURRIES WITH UNRESTRICTED VSBSYS...BUT THERE COULD BE A BRIEF
PERIOD OF LIGHT SNOW OR SNOW SHOWERS DROPPING THE VSBY TO AROUND
5-6SM. THE CEILING MAY BRIEFLY LOWER TO AROUND 2000-3000 FT AT OR
JUST BEFORE 12Z FRI THEN SCATTER OUT LATER FRI MRNG. NWLY SFC
WINDS SHOULD STRENGTHEN LATE TGT AND FRI MRNG TO AROUND 12 KTS...
THEN WEAKEN LATE FRI AFTN AND EVNG.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1116 PM CST THU FEB 14 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY
237 PM CST THU FEB 14 2013
MAIN FORECAST CONCERNS FOR THE SHORT TERM PERIOD:
1. TEMPERATURE AND CLOUD TRENDS THROUGHOUT
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING JUST OFF THE WEST COAST OF THE U.S. INTO BRITISH
COLUMBIA...WHILE TROUGHING COVERED MUCH OF EASTERN CANADA INTO THE
NORTHERN PLAINS AND WESTERN GREAT LAKES REGION. COMING THROUGH THE
TROUGH WAS A SHORTWAVE TROUGH APPROACHING THE SIOUX FALLS SOUTH
DAKOTA AREA...WHILE ANOTHER SHORTWAVE WAS SEEN IN CENTRAL
SASKATCHEWAN. THE SHORTWAVE THAT AFFECTED THE AREA LAST NIGHT INTO
THIS MORNING HAS MOVED OFF INTO LOWER MICHIGAN. RADAR IMAGERY SHOWED
A FEW RAIN/SNOW SHOWERS OVER MUCH OF WISCONSIN IN THE WAKE OF THE
LOWER MICHIGAN SHORTWAVE...DUE TO CYCLONIC FLOW OF LOW LEVEL
MOISTURE AND STEEP LOW LEVEL LAPSE RATES. TO THE WEST...RADAR ALSO
SHOWS A BAND OF RAIN/SNOW FROM CENTRAL SOUTH DAKOTA INTO NORTHWEST
IOWA...ASSOCIATED WITH THE SIOUX FALLS SHORTWAVE. NORTHWEST LOW
LEVEL WINDS BETWEEN THE TWO SHORTWAVES ARE GRADUALLY BRINGING IN
COLDER AIR. SOUNDINGS AT BIS...ABR...MPX AND INL ALL HAD 850MB TEMPS
DROP 3-4C BETWEEN 00Z AND 12Z...ALL BETWEEN -7 AND -12C AS OF 12Z.
SOME DRIER AIR WAS ALSO ACCOMPANYING THE NORTHWEST WINDS...NOTED BY
SATELLITE IMAGERY SHOWING CLEARING ACROSS NORTHERN MN.
TONIGHT THROUGH SATURDAY DEFINITELY ARE GOING TO BE COLDER THAN
AS OF LATE. THE SHORTWAVE OVER CENTRAL SASKATCHEWAN COMBINED WITH
ANOTHER SHORTWAVE CURRENTLY UP IN NORTHERN MANITOBA ARE GOING TO
DIG SOUTH...CARVING OUT A DEEP TROUGH OVER THE REGION BY 00Z
SATURDAY. 850MB TEMPS FALL AS THIS TROUGH FORMS...DROPPING TO -14
TO -18C BY 18Z FRIDAY AND -16 TO -20C BY 12Z SATURDAY PER MODEL
CONSENSUS. THOSE AT 12Z SATURDAY ARE 1.5 STANDARD DEVIATIONS BELOW
NORMAL. THE ONLY MITIGATING FACTOR TO THE COLD AIR WOULD BE THE
LACK OF SNOW OVER THE SOUTHWEST HALF OF THE FORECAST AREA...WHICH
IF SOME SUN CAN OCCUR WOULD REALLY HELP TO BOOST TEMPS UP GIVEN
THE CLIMBING SUN ANGLE NOW. GENERALLY FOLLOWED A BLEND OF THE
ECMWF AND 30 DAY BIAS CORRECTED GFS GRIDDED MOS GUIDANCE DATA
SINCE THEY HAVE BEEN DOING WELL AS OF LATE FOR HIGHS. LOWS ARE
HIGHLY CONTINGENT ON CLOUD COVER. AFTER SOME CLEARING TONIGHT...
MORE LOW TO MID CLOUDS MOVE IN FROM THE NORTHWEST FOR FRIDAY AND
FRIDAY NIGHT...ASSOCIATED WITH THAT SHORTWAVE DROPPING DOWN OUT OF
MANITOBA. THESE CLOUDS COMBINED WITH A NORTHWEST BREEZE SHOULD
HELP KEEP LOWS FROM BOTTOMING OUT...THUS A BLEND OF GUIDANCE FOR
LOWS SEEMS REASONABLE.
HANDLING CLOUD COVER SATURDAY COULD BE TRICKY. A RIDGE OF HIGH
PRESSURE IS PROGGED TO BUILD INTO THE WESTERN PORTIONS OF THE
FORECAST AREA. WILL FOLLOW THE GENERAL MODEL CONSENSUS OF THE LOW
CLOUDS BREAKING UP THROUGH THE DAY...DUE TO A COMBINATION OF THE LOW
LEVEL FLOW BECOMING ANTICYCLONIC AND DAYTIME MIXING. HOWEVER...IT IS
POSSIBLE THE CLOUDS COULD HANG ON FOR MUCH OF THE DAY. THIS COMBINED
WITH 850MB TEMPS STILL ONLY BETWEEN -14C WEST TO -20C EAST AT 18Z
WILL KEEP TEMPERATURES SEASONABLY COOL.
FOR SATURDAY NIGHT AND SUNDAY...A POTENT SHORTWAVE TROUGH IS PROGGED
TO DROP INTO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES...FORMING
TWO DISTINCT LOW PRESSURE AREAS ACROSS THE PLAINS DURING THE DAY
SUNDAY. A SOUTHERLY LOW LEVEL JET WILL DEVELOP AHEAD OF THESE TWO
LOWS...BRINGING UP WARMER AIR. AN INCREASE OF MID AND HIGH CLOUDS
ARE LIKELY TO ACCOMPANY THIS WARM ADVECTION. SO THE QUESTION FOR
LOWS SATURDAY NIGHT IS TIMING OF WHEN THE WARM ADVECTION STARTS UP
AND MID CLOUDS MOVE IN...VERSUS THE DEPARTURE TO THE EAST OF THE
SURFACE RIDGE. OUR WISCONSIN COUNTIES HAVE THE BEST SHOT OF
FAVORABLE RADIATIONAL COOLING CONDITIONS...THUS LEANED TOWARDS THE
COLDER SIDE OF GUIDANCE THERE. TEMPERATURES SHOULD RISE FROM LATE
SATURDAY NIGHT THROUGH SUNDAY AT MOST LOCATIONS AS SOUTHERLY WINDS
INCREASE. QUESTION ON SUNDAY IS HOW WARM DO WE GET...WITH 850MB
TEMPS THAT COULD APPROACH 0C NEAR CHARLES CITY IA BY 00Z MONDAY. IT
APPEARS SUNSHINE WILL BE ON THE INCREASE WEST OF THE MS RIVER AS THE
MID CLOUD LIFTS TO THE NORTH. GIVEN THE LACK OF SNOW OVER THE
SOUTHWEST HALF OF THE FORECAST AREA...LEANED MORE TOWARDS THE
CONSISTENTLY WARM ECMWF...BRINGING HIGHS AT LEAST TO THE MID 30S
AROUND CHARLES CITY.
PRECIPITATION WISE...MUCH OF THE SHORT TERM LOOKS DRY WITH RESPECT
TO REACHING 0.01" OF LIQUID EQUIVALENT IN ANY 12 HOUR PERIOD.
FLURRIES LOOK LIKELY...HOWEVER...FOR FRIDAY AND FRIDAY NIGHT OUT OF
THOSE LOW CLOUDS SINCE THEY EXIST WITHIN THE DENDRITIC GROWTH ZONE
AND HAVE WEAK LIFT FROM THE SHORTWAVE. PREVIOUS FORECAST MENTIONED
CONCERN THAT AS THE WARM ADVECTION STARTS UP SATURDAY NIGHT THAT WE
COULD SEE SOME SNOW FALL OUT OF THE ASSOCIATED MID CLOUD DECK. THAT
STILL REMAINS A CONCERN...THOUGH THINK FLURRIES WOULD BE THE MOST
THAT GETS PRODUCED. THEN AGAIN...THESE FLURRIES MIGHT BE ABSORBED BY
LOWER LEVEL DRY AIR. FOR NOW HAVE KEPT THE FORECAST DRY FOR SATURDAY
NIGHT AND SUNDAY.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
237 PM CST THU FEB 14 2013
MAIN CONCERNS FOR THE LONG TERM PERIOD...
1. TEMPERATURES AND PRECIPITATION POTENTIAL THROUGH MONDAY
2. BRIEF ARCTIC AIR SHOT FOR MID-WEEK
3. POTENTIAL FOR A WINTER STORM TO IMPACT THE AREA LATE IN THE WEEK
VERY GOOD MODEL AGREEMENT EXISTS AMONGST THE 14.12Z
ECMWF/GFS/CANADIAN/UKMET THROUGHOUT MUCH OF THE LONG TERM PERIOD.
FOR SUNDAY NIGHT INTO MONDAY...THE TROUGHING THAT WAS COMING ACROSS
THE NORTHERN ROCKIES EVOLVES BY MONDAY EVENING INTO A FULL
LONGITUDINAL TROUGH ACROSS THE CANADIAN AND U.S. PLAINS. THIS
TROUGHING EVENTUALLY PHASES TOGETHER AS IT CROSSES THE REGION AND
HEADS INTO THE GREAT LAKES FOR TUESDAY. PRIOR TO THE PHASING...A
REALLY STRONG PUSH OF WARM AIR COMES UP AT THE REGION WITH 850MB
TEMPS BETWEEN -2C AND +4C AT 12Z MONDAY. HAVE BOOSTED HIGH
TEMPERATURES FOR MONDAY AS A RESULT...THOUGH COULD BE EVEN HIGHER AS
NOTED BY THE 14.12Z ECMWF. ALSO...MODELS CONTINUE TO TREND
FARTHER WEST WITH THE SOUTHERN LOW COMING OUT OF THE SOUTHERN
PLAINS. AS SUCH...NOW ABOUT THE EASTERN TWO THIRDS OF THE AREA IS
AFFECTED BY LIGHT PRECIPITATION FOR MONDAY AFTERNOON AND EVENING.
THUS...HAVE EXPANDED LOW PRECIPITATION CHANCES FARTHER WEST AND
RAISED THEM 5-10 PERCENT. IF TRENDS CONTINUE...THESE CHANCES WILL
NEED TO BE RAISED MORE. WITH THE WARMER TEMPERATURES TOO...MIXING
WITH OR CHANGING TO RAIN IS AN ISSUE AS WELL.
AS THE PHASED TROUGH FORMS OVER THE AREA MONDAY NIGHT AND TUESDAY...
ARCTIC AIR FLOWS INTO THE REGION. 850MB TEMPS PLUMMET TO -12 TO -14C
BY 12Z TUESDAY AND -14 TO -20C BY 12Z WEDNESDAY. THUS...A MUCH
COOLER PERIOD IS ON TAP AGAIN. CANADIAN HIGH PRESSURE BUILDING DOWN
INTO THE NORTHERN PLAINS...IN THE WAKE OF THE PHASED TROUGH...WILL
PROVIDE FOR BLUSTERY CONDITIONS. WIND CHILLS RIGHT NOW LOOK TO STAY
JUST ABOVE ADVISORY CRITERIA...BOTTOMING OUT AT MOST IN THE -15 TO
-20F RANGE WEDNESDAY MORNING.
LASTLY...ABOUT THE POTENTIAL WINTER STORM LATE IN THE WEEK. THERE IS
SURPRISINGLY CONSISTENT AND GOOD MODEL AGREEMENT AMONGST THE
ECMWF...GFS AND THEIR RESPECTIVE ENSEMBLES OF A DEEP TROUGH FORMING
OVER THE WESTERN U.S. ON WEDNESDAY. AS THIS TROUGH HEADS EAST
TOWARDS THE PLAINS...A DEEP LOW PRESSURE AREA DEVELOPS OVER THE
CENTRAL PLAINS BY THURSDAY MORNING. THERE ARE A FEW QUESTIONS FROM
HERE ON...WHICH MAY TAKE AT LEAST A FEW MORE DAYS TO ANSWER:
1. TIMING AND STRENGTH AS USUAL
2. HOW QUICK DOES THE PRECIPITATION SPREAD INTO THE AREA IF IT
INDEED AFFECTS US
3. HOW MUCH PRECIPITATION WOULD OCCUR
4. DEPENDING ON HOW MUCH THE SYSTEM WRAPS UP...MAY HAVE TO DEAL WITH
PRECIPITATION TYPE ISSUES
FOR NOW HAVE STAYED WITH A CONSENSUS APPROACH...WHICH BY THURSDAY
NIGHT YIELDS 50-60 PERCENT CHANCES OF PRECIPITATION REGION-WIDE. ALL
PRECIPITATION RIGHT NOW LOOKS TO FALL AS SNOW...WHICH COULD BE
SIGNIFICANT. SINCE THE STORM IS VERY FAR OUT IN THE FORECAST AND
JUST BEYOND THE CURRENT HWO PERIOD...HAVE KEPT THE MENTION OF THE
STORM TO THIS DISCUSSION ONLY. HOWEVER...IF TRENDS ON THIS SYSTEM
CONTINUE...LATER SHIFTS WILL NEED TO MENTION THE STORM IN THE HWO
AND IN OTHER DECISION SUPPORT SERVICES.
&&
.AVIATION...THROUGH 06Z SATURDAY
1116 PM CST THU FEB 14 2013
SKIES HAVE CLEARED AT BOTH RST AND LSE...SO THE QUESTION NOW IS
WHEN DO THE CLOUDS RETURN AND WILL THEY PRODUCE ANY FLURRIES. THE
NEXT BATCH OF CLOUDS APPEARS TO BE FORMING IN NORTHWEST MINNESOTA
AND SHOULD REACH THE AREA AROUND OR SHORTLY AFTER SUN RISE FRIDAY.
A FEW FLURRIES HAVE BEEN REPORTING UNDER THIS DECK...SO CAN NOT
RULE OUT A FEW AS THESE CLOUDS ARRIVE FRIDAY MORNING THOUGH
VISIBILITY IS EXPECTED TO STAY AT 6SM OR GREATER. CEILINGS WILL
LIKELY VARY BETWEEN VFR AND MVFR THROUGH MUCH OF FRIDAY...SO IT
IS HARD TO PIN DOWN SPECIFICS ON THE TIMING OF THESE CHANGES.
BASED ON FORECAST SOUNDINGS...IT APPEARS THAT THE SATURATED LAYER
IS MAINLY MVFR...SO WENT WITH THAT FOR CEILINGS FOR MUCH OF THE
DAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
237 PM CST THU FEB 14 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
940 AM EST FRI FEB 15 2013
.UPDATE...
THE NEAR TERM AND AVIATION SECTIONS HAVE BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 335 AM EST FRI FEB 15 2013
A BROAD UPPER LEVEL LOW WILL SPREAD ACROSS THE GREAT LAKES REGION
THROUGH TOMORROW BRINGING PERIODIC CHANCES FOR LIGHT SNOW SHOWERS.
HIGH PRESSURE WILL THEN BUILD INTO CENTRAL INDIANA BY SUNDAY AS
THE AFOREMENTIONED LOW PUSHES OFF TO THE EAST. AFTER DRY CONDITIONS
ON SUNDAY...ANOTHER UPPER LEVEL LOW WILL BRING PRECIP TO THE
REGION ON MONDAY AND TUESDAY.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 940 AM EST FRI FEB 15 2013
SCATTERED LIGHT SNOW AND FLURRIES EXPANDING ACROSS MUCH OF THE
NORTHERN PART OF THE FORECAST AREA SO FAR THIS MORNING AS THE
UPPER WAVE AND ITS ASSOCIATED FORCING MOVE THROUGH. TEMPS ACROSS
THE FORECAST AREA WERE IN THE LOWER AND MID 30S AT 14Z.
FORECAST IN GREAT SHAPE AND HAVE MADE ONLY MINOR ADJUSTMENTS TO
ACCOUNT FOR ONGOING OBS. SCATTERED LIGHT SNOW DEVELOPING A TOUCH
FASTER THAN PREVIOUSLY THOUGHT AS THE STRONGEST FORCING ALOFT
ALREADY INTO THE REGION. EXPECT SNOW SHOWERS TO CONTINUE THROUGH
MID AFTERNOON AS THE UPPER WAVE TRANSITIONS ACROSS THE REGION AND
WILL CONTINUE WITH CHANCE POPS. RAP SOUNDINGS SHOWING SOME WEAK
INSTABILITY DEVELOPING THROUGH EARLY AFTERNOON ALONG WITH
STEEPENING LAPSE RATES UP THROUGH ABOUT 800MB. THIS WILL
CONTRIBUTE TO THE DEVELOPMENT OF A FEW STRONGER CONVECTIVE SNOW
SHOWERS BUT WITH SURFACE TEMPS NEAR TO JUST ABOVE FREEZING AND
LIMITED MOISTURE AVAILABLE...ACCUMULATION POTENTIAL WILL BE
MITIGATED WITH MOST LOCATIONS ONLY SEEING A FEW TENTHS AT BEST.
THE BIGGER IMPACT TO TRAVEL LIKELY TO BE QUICK DROPS IN
VISIBILITIES WITHIN HEAVIER SNOW SHOWERS. MOST PRECIP WILL BE DONE
BY MID AFTERNOON AS THE UPPER WAVE MOVES INTO OHIO. FORECAST HIGHS
IN THE LOW/MID 30S STILL LOOK TO BE ON TRACK.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 335 AM EST FRI FEB 15 2013
DRY CONDITIONS WILL PREVAIL TONIGHT...BUT THE POTENTIAL FOR
PERIODIC SNOW SHOWERS WILL RETURN EARLY SATURDAY MORNING AND
LINGER THROUGH THE DAY AS ANOTHER WEAKER SHORTWAVE PASSES IN THE
UPPER FLOW. WEAK LAKE EFFECT ENHANCEMENT COULD CONTRIBUTE TO SOME
LIGHT SNOW SHOWERS OVER THE NORTHEAST/EASTERN PORTIONS OF CENTRAL
INDIANA THROUGH SATURDAY NIGHT.
HIGH PRESSURE WILL RE-ESTABLISH ITSELF OVER THE AREA ON SATURDAY
NIGHT...RESULTING IN DRY CONDITIONS FOR SUNDAY. MODELS SEEM TO
HAVE A GOOD HANDLE ON THE COOLER AIR ASSOCIATED WITH THE SECOND
WAVE ON SATURDAY...SO STUCK CLOSE TO GUIDANCE.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 330 AM EST FRI FEB 15 2013
MAIN FOCUS TO THE EXTENDED WILL BE ON POPS AS TWO SEPARATE SYSTEMS
WILL BRING CHANCES TO CENTRAL INDIANA NEXT WEEK.
LONG RANGE MODELS...INCLUDING THE ENSEMBLES...ARE HAVING SOME
DIFFERENCES HANDING THESE SYSTEMS WITH THE 00Z GEFS AND GFS
GENERALLY QUICKER AND NORTHEAST WITH THE ASSOCIATED LOW PRESSURE
CENTERS AND QPF ACROSS THE FORECAST AREA. THE REGIONAL
INITIALIZATION FORECAST SEEMS TO TAKE A BLEND OF THE EXTENDED OUTPUT
WHICH LOOKS REASONABLE.
A MODEL BLEND WOULD BRING A WARM FRONT ASSOCIATED WITH AN OCCLUDED
SYSTEM ACROSS CENTRAL INDIANA ON MONDAY FOLLOWED BY A COLD FRONT
MONDAY NIGHT. MODELS BRING MOST OF THE QPF IN MONDAY AFTERNOON AND
NIGHT AND BUFKIT PARTIAL THICKNESS METHOD ALONG WITH SOUNDINGS
SUGGEST ALL RAIN UNTIL AFTER 06Z...WHEN THE RAIN SHOULD MIX WITH OR
TURN TO SNOW FROM NORTHWEST TO SOUTHEAST BEHIND THE COLD FRONT. LEFT
SMALL TUESDAY MORNING SNOW CHANCES IN...BUT THEN HIGH PRESSURE WILL
BUILD IN FROM CENTRAL CANADA LEADING TO DRY AND COLDER WEATHER
THROUGH WEDNESDAY NIGHT. FINALLY...THE 12Z GFS AND GEFS WERE FURTHER
NORTH AND STRONGER BRINGING A STRONG LOW PRESSURE SYSTEM TO CENTRAL
MISSOURI BY 00Z FRIDAY FEBRUARY 22. THE 00Z ECMWF HAD IT MORE
UNORGANIZED ACROSS OKLAHOMA AND ARKANSAS BY THEN. AS A RESULT...NICE
GULF RETURN FLOW HAPPENS A BIT QUICKER IN THE GFS AND GEFS SOLUTIONS
AS DOES QPF BY 18Z MONDAY. AGAIN...WITH MODEL UNCERTAINTY...WILL
ACCEPT THE REGIONAL INITIALIZATION WHICH BRINGS LIKELY POPS
SOUTHWEST HALF ON THURSDAY. BUKFIT PARTIAL THICKNESSES SUGGEST THE
PRECIPITATION WILL START OFF ALL SNOW AND THEN MIX WITH RAIN IN THE
AFTERNOON FROM SOUTHWEST TO NORTHEAST.
WILL NOT MAKE ANY CHANGES TO TEMPERATURES AS OF YET WITH WELL ABOVE
NORMAL HIGHS IN THE 40S AND 50S ON MONDAY FALLING TO NORMAL TO BELOW
NORMAL THE REST OF THE WEEK.
&&
.AVIATION /DISCUSSION FOR THE 151500Z TAF UPDATE/...
ISSUED AT 940 AM EST FRI FEB 15 2013
CEILINGS OSCILLATING BETWEEN 1500 AND 3000 FT AT ALL TERMINALS
ALREADY THIS MORNING...WITH LIGHT SNOW SHOWERS AND FLURRIES
EXPANDING ACROSS THE NORTHERN COUNTIES. HAVE INCLUDED A MENTION OF
5SM -SN AT BOTH KIND AND KLAF IN TEMPO GROUPS FOR THE NEXT FEW
HOURS AS THE UPPER LEVEL DISTURBANCE PASSES THROUGH THE REGION.
WINDS WILL VEER TO A NORTHWEST DIRECTION BY MIDDAY AND CONTINUE
INTO THE AFTERNOON. REST UNCHANGED.
12Z DISCUSSION FOLLOWS.
ELONGATED UPPER LEVEL DISTURBANCE WILL DROP SOUTHEAST ACROSS THE
TERMINALS TODAY PERHAPS TRIGGERING A FEW SNOW SHOWERS THIS MORNING
ENDING AFTER 16Z AT LAF. HOWEVER...LITTLE IN THE WAY SHOWING UP ON
UPSTREAM OBSERVATIONS AND MOISTURE CONFINED TO BELOW 750
MILLIBARS...SO WILL LEAVE THE TAFS DRY. SOME MVFR CEILINGS WERE
ACROSS NORTHERN ILLINOIS AND NOW LAF AND WILL SETTLE SOUTHEAST BUT
BECOME VFR ONCE AGAIN AFTER THE UPPER WAVE AND SNOW THREAT PASSES.
WOULD NOT RULE OUT A FEW LAKE EFFECT SNOW SHOWERS OVERNIGHT TONIGHT
AT IND AND LAF...BUT CHANCES TOO LOW TO MENTION.
NORTHWEST WINDS AROUND 10 KNOTS TODAY WILL BE LESS THAN 10 KNOTS
TONIGHT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...MK/RYAN
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1040 AM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA LATE THIS AFTERNOON INTO THE EVENING.
THIS SYSTEM WILL PROVIDE SNOW SHOWERS...WHICH MAY MIX WITH RAIN
IN THE SOUTH. IN THE WAKE OF THE FRONT...COLDER TEMPERATURES WITH
SNOW SHOWERS ARE EXPECTED THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
15Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ADJUST
POPS AND WX GRIDS THIS AFTERNOON.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A BROAD 500MB TROUGH
ACROSS THE MIDWEST WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY
FLOW AHEAD OF THIS FEATURE. 700MB OMEGA INDICATES AN AREA OF LIFT
ALONG THE OH/WV BORDER THAT IS SHIFTING NORTHEASTWARD INTO NORTH-
CENTRAL WV. THIS LIFT HAS BEEN SUFFICIENT FOR A MIX OF RAIN AND
SNOW SHOWERS MOVING INTO WV. AT THE SURFACE...A COLD FRONT EXTENDS
FROM ONTARIO SOUTHWARD ACROSS WESTERN OHIO. WITH THE
FRONT...SCATTERED LIGHT SNOW SHOWERS ARE MOVING ACROSS THE OHIO
VALLEY.
TODAY...THE INITIAL AREA OF 700MB OMEGA WILL SLIDE INTO NORTHERN
WV...SOUTHWEST PA...AND WESTERN MD...WITH A STRONG ENOUGH
1000-900MB MELTING LAYER ALLOWING FOR A RAIN/SNOW MIX TO PUSH
INTO THESE AREAS THROUGH THE EARLY AFTERNOON. PRECIPITATION WILL
BE ALL SNOW ACROSS THE ALLEGHENY FRONT AND LAUREL HIGHLANDS AS
ELEVATION NEGATES THE MELTING LAYER. ANY SNOW ACCUMULATION WITH THIS
WILL BE LIMITED TO THE HIGHER ELEVATIONS AND WILL BE GENERALLY
LESS THAN AN INCH. TEMPS TODAY ARE CLOSEST TO LAMP GUIDANCE WITH THE
HRRR TOO WARM. HIGHS WILL RANGE FROM THE MID 30S ALONG THE I-80
AND EASTERN RIDGES TO THE LOWER 40S IN NORTH-CENTRAL WV.
THE COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND IS
PROGGED TO BE BISECTING THE PITTSBURGH METRO AT 00Z. THE FRONT
WILL BRING SNOW SHOWERS TO THE AREA...CHANGING PRECIPITATION TO
ALL SNOW. WITH WARMER GROUND AHEAD OF THE FRONT AND SHOT OF CAA
LAGGING SOMEWHAT BEHIND THE FRONT...BELIEVE THIS WILL LIMIT
ACCUMULATION. THUS...WITH THE FRONTAL PASSAGE ITSELF...SNOW
ACCUMULATION WILL BE AN INCH OR LESS ACROSS THE AREA.
TONIGHT...THE FRONT WILL SLIDE EAST OF THE AREA AND CAA WILL
ENSUE. BEHIND THE FRONT...A WESTERLY COMPONENT WILL ALLOW FOR SOME
UPSLOPING ACROSS THE LAUREL HIGHLANDS AND ALLEGHENY FRONT
OVERNIGHT. HOWEVER...DEEP MOISTURE WILL NOT BE PRESENT IN THE WAKE
OF THE FRONT AND THUS ANTICIPATE THAT SNOW WILL BE GENERALLY LIGHT
WITH ADDITIONAL OVERNIGHT ACCUMULATION OF 1 TO 2 INCHES FOR
LOCATIONS ABOVE 2000 FT. ACROSS THE LOWLANDS...AN INVERSION AROUND
4-5KFT WILL LIMIT SNOW SHOWERS AND THUS ANTICIPATE LITTLE OR NO
ACCUMULATION OVERNIGHT. WITH A POST-FRONTAL ARCTIC AIR MASS
SETTLING INTO THE REGION...TEMPS TONIGHT WILL BE NOTICEABLY
COLDER. A MAV/MET BLEND WAS USED WITH LOWS RANGING FROM THE MID
TEENS NORTH AND EAST OF PITTSBURGH TO NEAR 20 IN PORTIONS OF
EASTERN OHIO AND NORTHERN WV.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
SNOW SHOWERS WILL REDEVELOP LATER SATURDAY AND CONTINUE INTO
EARLY SUNDAY AS A TROUGH AXIS...ASSOCIATED WITH UPPER LEVEL LOW
OVER THE NORTHERN GREAT LAKES...SWINGS THROUGH. THIS SYSTEM WILL
ALSO PROVIDE ANOTHER REINFORCING SHOT OF COLD AIR.
SNOW SHOWERS WILL DIMINISH ON SUNDAY AS WINDS BACK TO THE WEST AND
SFC HIGH MOVES THROUGH THE MID-ATLANTIC.
TEMPS THROUGH THE WEEKEND WILL BE BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL BRING DRY WEATHER AND SEASONABLE TEMPERATURES FOR
SUNDAY NIGHT INTO MONDAY NIGHT. A STRONG COLD FRONT WILL PUSH ACROSS
THE DISTRICT TUESDAY BRINGING SHOWERS AND WARMER TEMPERATURES AHEAD
OF THE FRONT. AS THE FRONT PUSHES EAST OF THE DISTRICT RAIN SHOWERS
WILL CHANGE TO SNOW SHOWERS AS COLDER TEMPERATURES MOVE IN FOR
TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE WILL BRING A RETURN OF
DRY WEATHER FOR WEDNESDAY NIGHT INTO THURSDAY.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
SCATTERED SHOWERS ARE EXPECTED WITH AN UPPER WAVE EARLY THIS
AFTERNOON...BUT CONFIDENCE IS ONLY HIGH ENOUGH AT MGW TO INCLUDE
IN TAFS AT THIS TIME. HIGHEST CHANCES FOR PRECIPITATION WILL BE
SOUTH OF PITTSBURGH.
A STRONGER COLD FRONT SHOULD BRING ANOTHER WIND SHIFT THIS EVENING
ALONG WITH THE POSSIBILITY OF CIGS DROPPING BACK TO MVFR IN MORE
SCATTERED SHOWERS.
.OUTLOOK.../SATURDAY THROUGH TUESDAY/...
PERIODIC RESTRICTIONS ARE POSSIBLE THROUGH SUNDAY AS SEVERAL FAST
MOVING DISTURBANCES MOVE ACROSS THE GREAT LAKES REGION. HIGH
PRESSURE AND VFR CONDITIONS ARE FORECAST TO RETURN MONDAY AND LAST
UNTIL A COLD FRONT APPROACHES TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1054 AM EST FRI FEB 15 2013
.SYNOPSIS...
ISSUED AT 1053 EST FRI FEB 15 2013
SNOW WILL INTENSIFY THIS EVENING AND LINGER THROUGH SATURDAY
EVENING. THIS WILL BRING SIX TO NINE INCHES OF SNOW TO THE
LAKESHORE...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. THIS GREATEST
SNOWFALL AMOUNTS ARE EXPECTED MAINLY ALONG THE LAKESHORE COUNTIES.
FARTHER INLAND CLOSER TO THE US-131 CORRIDOR...TOTALS OF 2 TO 5
INCHES WILL BE MORE COMMON...WITH EVEN LESSER AMOUNTS FARTHER
EAST.
THE SNOW WILL DIMINISH INTO SATURDAY NIGHT WITH SOME SUNSHINE
EXPECTED BY SUNDAY. THEN ANOTHER PERIOD OF SNOW IS EXPECTED FOR
MONDAY AND MONDAY NIGHT. WITH MORE SNOW POSSIBLE AGAIN BY THE END
OF THE WORK WEEK.
&&
.UPDATE...
ISSUED AT 1053 EST FRI FEB 15 2013
TRIMMED BACK SNOW ACCUMULATIONS TODAY BASED ON LATEST OBSERVATIONS
AND MODEL GUIDANCE. LATEST RUNS OF THE RAP MODEL SUGGEST ACCUMULATING
SNOW WILL BE DELAYED UNTIL AFTER 6 TO 7 PM TONIGHT. ALSO LOWERED
INLAND SNOW AMOUNTS OVERALL AS WE EXPECT A FAIRLY SHARP DROP OFF
IN ACCUMULATIONS AWAY FROM THE LAKE SHORE BASED ON THE REASONING
IN THE PREVIOUS DISCUSSION REGARDING CROSS HAIR SIGNATURE
PLACEMENT AND LIKELY INLAND CELLULAR NATURE OF PRECIPITATION
SATURDAY. WILL BE ISSUING AN ADVISORY UPDATE SHORTLY TO REFLECT
THIS CHANGE IN THINKING.
WE ARE LOOKING AT THE POTENTIAL FOR SIGNIFICANT SNOWFALL ENHANCEMENT
ACROSS OUR NORTHERN ZONES AFTER MIDNIGHT AS THE NAM SUGGESTS A
MESOLOW WILL ZIP SOUTHEAST THROUGH LUDINGTON. THIS WILL BE
SOMETHING TO WATCH FOR THE AFTERNOON UPDATE.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 342 AM EST FRI FEB 15 2013
HAVE DECIDED TO GO WITH A LAKE EFFECT SNOW ADVISORY FOR ROUGHLY THE
WESTERN HALF OF THE CWA STARTING LATE THIS AFTERNOON AND CONTINUING
INTO SATURDAY EVENING.
LONG DURATION LAKE EFFECT EVENT WILL RAMP UP LATE THIS AFTERNOON A
STRONG WAVE ENERGY PIVOTS IN. INVERSION HEIGHTS WILL CLIMB LEADING
TO AN INCREASED INTENSITY TO THE THE SNOW SHOWERS. FAVORABLE OMEGA
CROSS HAIR SIGNATURE WITHIN THE DGZ LINES UP ALONG THE LAKE SHORE
COUNTIES BY THIS EVENING AND REMAINS PERSISTENT RIGHT INTO SATURDAY
EVENING. MEAN FLOW WILL WAVER SOMEWHAT...SO NOT SURE HOW PERSISTENT
THE SNOW WILL BE AT ANY ONE SPOT...HENCE THE ADVISORY VERSUS A
WARNING. THE FLOW WILL BE 290-300 MUCH OF TONIGHT...BUT THEN IT
BECOMES 310-340 FOR SATURDAY/SATURDAY EVENING WHICH WILL SHIFT THE
SNOW BANDS A BIT.
ANOTHER CONSIDERATION WILL BE THE IMPACT OF THE HIGHER SUN ANGLE
THIS TIME OF YEAR. WE ARE GETTING INTO THAT TIME OF YEAR WHERE THE
LAKE EFFECT CAN BECOME MORE CELLULAR DUE TO DAYTIME CONVECTIVE
ELEMENTS. THIS COULD ALSO LOWER ACCUMS A BIT...OR AT LEAST AFFECT A
PERSISTENT DAYTIME HEAVY SNOW BAND.
ALL IN ALL...EXPECT SOME AREAS ALONG THE LAKE SHORE COUNTIES MAY SEE
UP TO NINE INCHES OF SNOW OVER THE 30 HOUR HEADLINE PERIOD. AMOUNTS
WILL LOWER FURTHER INLAND...BUT THE U.S. 131 COUNTIES WILL STILL SEE
A PERSISTENT SNOW WITH 4 TO 8 INCHES POSSIBLE THERE. EASTERN
COUNTIES WILL SEE SNOW TOO DUE THE SYNOPTIC SHORT WAVE AND SOME LAKE
ENHANCEMENT. FEEL A 2 TO 4 INCH ACCUM SHOULD OCCUR OVER THE SAME
30 HOUR PERIOD.
OTHERWISE...UNTIL WE SEE THE RAMP UP LATE THIS AFTERNOON...THE SNOW
SHOWERS WILL CONTINUE ON A LIGHTER RATE. INVERSION LEVELS STAY
AROUND 5K FEET UNTIL THE SHORT WAVE ARRIVES.
.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 342 AM EST FRI FEB 15 2013
TWO STORMS ARE EXPECTED NEXT WEEK AND THE SECOND ONE COULD BE MAJOR.
FIRST UP...A CLIPPER MOVES TOWARDS LOWER MICHIGAN ON MONDAY WHILE
PHASING WITH A SOUTHERN STREAM LOW RIGHT OVER LOWER MICHIGAN.
FORECAST CONFIDENCE IS HIGH IN THAT THE MODELS HAVE AGREED ON A RAIN
AND SNOW MIX MOVING IN LATE MONDAY...CHANGING TO SNOW MONDAY NIGHT.
THIS IS FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY
AFTERNOON INTO WEDNESDAY.
SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON
WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM
APPEARS TO BE TAKING SHAPE ACROSS THE PLAINS. THE GULF IS WIDE OPEN
FOR THIS ONE AND A COLD SFC HIGH IS IN PLACE ACROSS EASTERN CANADA.
MODELS HAVE SHOWN THIS STORM FOR A COUPLE DAYS NOW WITH PRETTY GOOD
CONSISTENCY. THURSDAY COULD SEE THE ONSET OF THE STORM WITH SNOW
BREAKING OUT LATE IN THE AFTERNOON...ALTHOUGH BOTH THE GFS AND ECMWF
SHOW THE HEAVIER SNOW NOT ARRIVING UNTIL THURSDAY NIGHT OR FRIDAY.
EVEN AT THIS LONG RANGE THE MODELS ARE SHOWING STRONG F-GEN
POTENTIAL SO THIS COULD BE THE BIGGEST SYNOPTIC SNOW EVENT OF THE
WINTER SO FAR.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 647 AM EST FRI FEB 15 2013
VFR CONDITIONS EXPECTED TO PREVAIL THIS MORNING BUT LAKE EFFECT
SNOW SHOWERS WILL START THIS AFTERNOON WITH IFR CONDITIONS
EXPECTED FROM MKG TO AZO AND POSSIBLY INTO BTL AND GRR AT TIMES
TONIGHT.
&&
.MARINE...
ISSUED AT 1053 EST FRI FEB 15 2013
KEPT THE SMALL CRAFT ADVISORY INTACT...BUT THERE ARE INDICATIONS
WE WILL STAY BELOW THRESHOLDS AFTER THIS EVENING. WE ARE CONSIDERING
SCALING BACK THE DURATION OF THE SCA FOR THE AFTERNOON UPDATE.
&&
.HYDROLOGY...
ISSUED AT 342 AM EST FRI FEB 15 2013
ONLY ONE FLOOD ADVISORY REMAINS ON THE PERE MARQUETTE AT
SCOTTVILLE. THIS IS EXPECTED TO REMAIN FAIRLY STEADY OVER THE SHORT
TERM. OTHERWISE WITH THE POLAR AIR COMING IN ANY MELT OFF HAS ENDED
THROUGH AT LEAST THE WEEKEND.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...LAKE EFFECT SNOW ADVISORY FROM 4 PM THIS AFTERNOON TO 10 PM EST
SATURDAY FOR MIZ037-043-050-056-064-071-072.
LAKE EFFECT SNOW ADVISORY FROM 10 PM THIS EVENING TO 7 PM EST
SATURDAY FOR MIZ038-044-057-065-073.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...JK
LONG TERM...OSTUNO
AVIATION...OSTUNO
HYDROLOGY...JK
MARINE...TJT
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
650 AM EST FRI FEB 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 458 AM EST FRI FEB 15 2013
THE LOW THAT AFFECTED THE SOUTHERN PART OF THE CWA YESTERDAY MORNING
HAS LEFT A SURFACE TROUGH OVER EASTERN LAKE SUPERIOR. RUC ANALYZED
850MB TEMPS ARE AROUND -16C OVER LAKE SUPERIOR AND NORTH-NORTHWEST
WINDS ALOFT HAS LED TO LAKE EFFECT SNOW OVER PORTIONS OF LAKE
SUPERIOR EARLY THIS MORNING. THE BEST SNOW HAS BEEN OCCURRING OVER
IN THE MULTI-BANDED SNOW OVER EASTERN LAKE SUPERIOR...WHERE
INVERSION HEIGHTS ARE AROUND 8KFT BASED OF KMQT RADAR AND THERE IS
ENOUGH MOISTURE PRESENT. FARTHER WEST...DRIER AIR THIS EVENING HAS
LIMITED MUCH OF THE LAKE EFFECT SNOW THUS FAR. BUT WITH A SHORTWAVE
JUST NORTHWEST OF LAKE SUPERIOR EXPECTED TO INCREASE MOISTURE ACROSS
THE AREA...HAVE SEEN A SLIGHT INCREASE IN COVERAGE ON SATELLITE
BETWEEN THE HIGHER CLOUDS. THIS WILL ALSO INCREASE THE INVERSION
HEIGHTS FROM 3-4KFT TO 6-8KFT OVER THE WEST. THUS...EXPECT THE LAKE
EFFECT TO TO CONTINUE TO INCREASE IN INTENSITY/COVERAGE FOR BOTH
WEST/EAST THROUGH THE MORNING HOURS FOR LOCATIONS FAVORED BY
NORTH-NORTHWEST WINDS. WITH MUCH OF THE CONVECTIVE PORTION OF THE
CLOUD WITHIN THE DGZ...EXPECT VERY FLUFFY LAKE EFFECT AND SNOW
RATIOS IN THE 30-1 RANGE. THIS WILL ALLOW FOR QUICK ACCUMULATIONS IN
THE STRONGER BANDS...ESPECIALLY SINCE WINDS WILL HAVE DECREASED FROM
THE 20-30KTS SEEN AROUND MIDNIGHT. ONE ITEM OF CONCERN FOR THE
INTENSITY THIS MORNING OVER THE WEST...ESPECIALLY OVER THE
KEWEENAW...IS THE 30 DEGREES OF SHEAR BETWEEN THE TOP OF THE
INVERSION /800MB/ AND THE MIDDLE OF THE CONVECTIVE CLOUD /900MB/.
THIS MAY LIMIT THE DEEP AND ORGANIZED BANDS THAT WOULD PROMOTE VERY
HEAVY SNOW.
AS THIS SHORTWAVE DEPARTS LATE THIS MORNING AND INTO THE
AFTERNOON...WOULD THINK THE LAKE EFFECT WILL DIMINISH SOME AS
DIURNAL MIXING HELPS REDUCE THE INTENSITY OF THE BANDS OVER THE
WEST. IN ADDITION...THE DEEPER MOISTURE SLIDES MORE OVER THE EASTERN
LAKE WHILE WINDS BACK TO THE NORTHWEST. THIS WILL HELP REDUCE THE
INTENSITY OF THE BANDS SLIGHTLY...BUT THE BACKING WINDS WILL CAUSE
THE HEAVIEST SNOW TO SHIFT FROM THE MORE NNW FAVORED AREAS TO NW
AREAS. ALTHOUGH THIS WILL SPREAD THE LAKE EFFECT TO MORE AREAS...IT
MIGHT CAUSE SOME LIMITATION IN THE HIGHER SNOWFALL AMOUNTS IN ONE
LOCATION TO BE PRIMARILY IN THE ADVISORY CRITERIA CATEGORY. HIGHER
RESOLUTION MODELS DO PICK UP ON BOTH OF THESE FEATURES WELL AND
WILL FOLLOW THEIR TIMING FOR THE MOVEMENT AND INTENSITY FOR THIS
AFTERNOON. OVER THE EAST...INVERSION HEIGHTS OVER THE EAST RISE TO
8-10KFT THIS AFTERNOON AND CONTINUE INTO THE EVENING. WITH THE
DEEPER MOISTURE FROM THE SHORTWAVE AND SOME ENHANCED CONVERGENCE ON
THE SOUTHWEST EDGE OF THE LAKE EFFECT...EXPECT A FAIRLY HEAVY BAND
OR TWO WITHIN THE MULTI-BAND SNOW TO SETUP SOMEWHERE BETWEEN
MUNISING AND GRAND MARAIS. THIS NW WIND WILL ALSO LEAD TO
AN INCREASED PERIOD OF SNOW FOR NORTHERN LUCE COUNTY LATER THIS
AFTERNOON AND INTO THE EARLY EVENING. THIS IS DUE TO THE LONGER
FETCH THAN THEY WILL SEE FOR THE FIRST PART OF TODAY WITH THE
NORTHERLY WINDS. THERE IS THE POTENTIAL FOR SOME HEAVIER SNOWFALL
RATES AND ADVISORY SNOWFALL DURING THAT PERIOD...SO FELT
COMFORTABLE ISSUING AN ADVISORY EVEN THOUGH THERE IS SOME CONCERN
ON THE TIMING OF WHEN THE BAND WILL BACK TO THE WEST TONIGHT AS
WINDS SHIFT TO THE NORTHEAST.
COLDER AIR ARRIVES TONIGHT...WITH 850MB TEMPS FALLING TOWARDS -22C
OVER THE WEST AND -20C OVER THE EAST. OVER THE WEST...THE PRODUCES
SOME CONCERN AS IT WILL PUT A PORTION OF THE CONVECTIVE CLOUD LAYER
AT THE TOP OF OR ABOVE THE DGZ AND LIKELY REDUCE THE SNOW RATIOS
SOMEWHAT. BUT INCREASED CONVERGENCE AS WINDS VEER TO A MORE
NORTHERLY DIRECTION DURING THE EVENING...DUE TO THE APPROACHING HIGH
IN THE NORTHERN PLAINS...WILL HELP INCREASE THE
INTENSITY OF THE SNOW BEFORE RETURNING TO MORE OF A GENERAL
MULTI-BAND LAKE EFFECT DURING THE OVERNIGHT HOURS. ALSO...ANOTHER
WEAK SHORTWAVE IN THE UPPER TROUGH WILL HELP INCREASE MOISTURE AND
KEEP INVERSION HEIGHTS IN THE 7-8KFT RANGE.
OVER THE EAST...THERE DOES SEEM TO BE A SLIGHT SLOWDOWN TO THE
WESTWARD TRANSITION OF THE LAKE EFFECT FROM THE NORTHWEST FAVORED
AREAS TO MORE NORTHERLY COMPARED TO 24HRS AGO...AS THE SURFACE
TROUGH OVER EASTERN LAKE SUPERIOR WEAKENS AND LAND BREEZE INFLUENCES
OFF ONTARIO TAKE OVER. SOME OF THE HIGHER RESOLUTION MODEL RUNS EVEN
TRY TO DEVELOP A WEAK MESO-LOW...WHICH WOULD COMPLICATE MATTERS
FURTHER. THUS...HAVE SLOWED THE WESTWARD TRANSITION A TOUCH AS THE
STRONGER BANDS MAKE THE WESTWARD TRACK ACROSS ALGER AND NORTHERN
SCHOOLCRAFT COUNTIES DURING THE NIGHT. THE INCREASED CONVERGENCE
WITHIN THIS BAND SHOULD LEAD TO SOME HEAVY SNOWFALL RATES AS IT
TRANSITIONS TO THE WEST.
ALL IN ALL...WILL LEAVE THE WARNING HEADLINES AS IS AND ADD
THE LUCE ADVISORY. THERE IS SOME SLIGHT CONCERN ON GETTING WARNING
AMOUNTS IN A WIDESPREAD AREA OF GOGEBIC/ONTONAGON
COUNTIES...BUT SHOULD EASILY SEE THE 12 INCHES IN 24HRS OVER
THE PORKIES. THE ONE QUESTION TO CARRY FORWARD TO THE DAY SHIFT IS
THE BORDERLINE ADVISORY SNOW FOR NORTHERN HOUGHTON AND KEWEENAW
COUNTIES. DIDN/T HAVE A GOOD FEELING ON ADVISORY AMOUNTS FOR
TODAY...ALTHOUGH WITH THE FLUFFY NATURE...COULD SEE A QUICK 4 INCHES
IN A LOCATION IF A BAND SETS UP FOR A FEW HOURS THIS MORNING. IN
ADDITION...WITH THE WINDS BACKING TO THE NW THIS AFTERNOON AND THEN
MORE OUT OF THE NORTH TONIGHT...WOULDN/T THINK THEY WOULD SEE A
PERSISTENT AREA OF TO RAISE CONFIDENCE ENOUGH FOR AN ADVISORY AT
THIS TIME. WITH THE MORE FAVORABLE MOISTURE TONIGHT AND SOME
ENHANCED CONVERGENCE...WOULD THINK THE BEST POTENTIAL FOR ADVISORY
SNOW WOULD BE OVER NORTHERN HOUGHTON COUNTY TOWARDS TWIN LAKES AND
THE DAY SHIFT MAY NEED TO SEE IF THAT IDEA CONTINUES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 458 AM EST FRI FEB 15 2013
SATURDAY...HIGHER RES MODELS SUGGEST THAT LAKE INDUCED TROUGHING WILL
FOCUS STRONGEST LOW LEVEL CONV AND LES INTO NORTH CENTRAL UPPER MI
BTWN MARQUETTE AND MUNISING. CONTINUED HIGH SLR NEAR 30/1 WOULD
SUPPORT SOME SNOW TOTALS IN THE 4 TO 7 INCH RANGE. CONFIDENCE IN THE
LOCATION OF THIS MESO SCALE FEATURE IS LIMITED BUT A HEADLINE FOR THE FAR
EASTERN PORTION OF MARQUETTE COUNTY MAY BE NECESSARY IF MODEL
AGREEMENT IS CONSISTENT. OVER THE WEST...LES WILL DIMINISH MORE
QUICKLY WITH THE SFC RIDGE AND DRIER AIR BUILDING INTO THE AREA
LEADING TO ADDITIONAL TOTALS ONLY IN THE 1 TO 4 INCH RANGE. A SHALLOW
DGZ WITH LESS FAVORABLE SLR WOULD ALSO LIMIT ACCUMULATION POTENTIAL.
SAT NIGHT...ALTHOUGH LES WILL CONTINUE TO DIMINISH WITH THE RIDGE
BUILDING INTO THE AREA...LIGHT WIND FIELDS AND CONTINUED LOW LEVEL
CONV...ESPECIALLY NEAR THE SHORELINE VCNTY KP53 COULD PRODUCE
SEVERAL ADDITIONAL INCHES OF SNOW. OTHERWISE...CLEARING WITH
FAVORABLE RADIATIONAL COOLING CONDITIONS WILL SUPPORT MIN TEMPS NEAR
THE LOWER END OF GUIDANCE...INTO THE -15F TO -20F RANGE INTERIOR
WEST HALF.
SUN AND SUN NIGHT...A PROGRESSIVE PATTERN WITH THE SFC RIDGE
SHIFTING TO THE EAST...A TROUGH INTO THE NRN PLAINS TO THE UPPER MS
VALLEY AND A STRENGTHENING WAA PATTERN WILL ALLOW MOISTURE TO
INCREASE. BOTH THE GFS AND ECMWF SUGGEST THE STRONGEST ISENTROPIC
LIFT WILL REMAIN NORTH OF THE CWA WITH ONLY CHANCE POPS FOR LIGHT
SNOW BY LATE SUN NIGHT.
MON INTO MON NIGHT...MODELS WERE SIMILAR WITH A MID/UPPER LEVEL
TROUGH INTO THE WRN GREAT LAKES. THE ECMWF WAS A BIT SLOWER AND MORE
AGGRESSIVE IN DIGGING THE TROUGH AND SFC LOW TO THE SOUTH COMPARED
TO THE GFS...BUT NOT AS MUCH AS THE CMC...RESULTING IN GREATER PCPN
ACROSS UPPER MICHIGAN. WITH SUFFICIENT MOISTURE INFLOW BRINGING PWAT
TO NEAR 200 PCT NORMAL THE POTENTIAL REMAINS FOR MODERATE SNOW
ACCUMULATIONS WITH THE SYSTEM.
TUE-WED...SIGNFICANT/HEAVY LES WILL BE POSSIBLE IN THE WAKE OF THE
LOW WITH STRONG CAA DROPPING 850 MB TEMPS INTO THE -15C TO -20C
RANGE ALONG WITH CYCLONIC NNW FLOW AND ABUNDANT 850-700
MOISTURE...PER ECMWF. LES SHOULD DIMINISH WED AS RIDGING AGAIN
BUILDS INTO THE REGION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 649 AM EST FRI FEB 15 2013
LAKE EFFECT SNOW SHOWERS WILL BE ON THE INCREASE AT KCMX/KIWD
THROUGH THE MORNING HOURS. EXPECT THE STRONGEST SNOW THROUGH MUCH
OF THE DAYTIME HOURS AT KIWD WITH THE MORE FAVORABLE AND
CONVERGENT FLOW THIS MORNING. BUT AS WINDS BACK MORE TO
THE NORTHWEST...EXPECT CONDITIONS TO DROP TO IFR/MVFR AT
KCMX WHILE THEY BECOME LESS FAVORABLE AT KIWD. EXPECT PERIODS OF
ALTERNATE LANDING MINIMUMS VISIBILITIES TONIGHT AS LOW LEVEL
CONVERGENCE INCREASES WITH WINDS VEERING TO THE NNW...INCREASING
THE INTENSITY OF THE SNOW.
AT KSAW...UNFAVORABLE DOWNSLOPING NW FLOW WILL GENERALLY KEEP
BORDERLINE MVFR/VFR CEILINGS THROUGH THE PERIOD WITH OCCASIONAL
SNOW SHOWERS FROM ENHANCED SNOW OFF THE HURON MOUNTAINS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 AM EST FRI FEB 15 2013
NORTHWEST WINDS OF 20-30KTS WILL DIMINISH TODAY AS HIGH PRESSURE IN
THE NORTHERN PLAINS SLOWLY SHIFTS EAST INTO THE UPPER GREAT LAKES.
THIS WILL CONTINUE TO DIMINISH THE WINDS ON THROUGH SATURDAY.
BEFORE THE WINDS DIMINISH...HEAVY FREEZING SPRAY IS EXPECTED OVER
PORTIONS OF LAKE SUPERIOR THROUGH TONIGHT. AS THE HIGH SHIFTS EAST
ON SUNDAY A LOW PRESSURE SYSTEM WILL APPROACH THE UPPER GREAT LAKES
ON MONDAY AND MOVE THROUGH ON TUESDAY. THIS WILL BRING INCREASING
SOUTHERLY FLOW ON MONDAY...TO 25KTS OVER THE EAST...AND THEN STRONG
NORTHERLY WINDS BEHIND THE LOW ON TUESDAY AFTERNOON...TO 30KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SATURDAY FOR MIZ006-085.
LAKE EFFECT SNOW ADVISORY UNTIL 5 AM EST SATURDAY FOR MIZ007.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST /NOON CST/ SATURDAY FOR
MIZ002-009.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR
LSZ264>266.
HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR
LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...JLB
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
501 AM EST FRI FEB 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 458 AM EST FRI FEB 15 2013
THE LOW THAT AFFECTED THE SOUTHERN PART OF THE CWA YESTERDAY MORNING
HAS LEFT A SURFACE TROUGH OVER EASTERN LAKE SUPERIOR. RUC ANALYZED
850MB TEMPS ARE AROUND -16C OVER LAKE SUPERIOR AND NORTH-NORTHWEST
WINDS ALOFT HAS LED TO LAKE EFFECT SNOW OVER PORTIONS OF LAKE
SUPERIOR EARLY THIS MORNING. THE BEST SNOW HAS BEEN OCCURRING OVER
IN THE MULTI-BANDED SNOW OVER EASTERN LAKE SUPERIOR...WHERE
INVERSION HEIGHTS ARE AROUND 8KFT BASED OF KMQT RADAR AND THERE IS
ENOUGH MOISTURE PRESENT. FARTHER WEST...DRIER AIR THIS EVENING HAS
LIMITED MUCH OF THE LAKE EFFECT SNOW THUS FAR. BUT WITH A SHORTWAVE
JUST NORTHWEST OF LAKE SUPERIOR EXPECTED TO INCREASE MOISTURE ACROSS
THE AREA...HAVE SEEN A SLIGHT INCREASE IN COVERAGE ON SATELLITE
BETWEEN THE HIGHER CLOUDS. THIS WILL ALSO INCREASE THE INVERSION
HEIGHTS FROM 3-4KFT TO 6-8KFT OVER THE WEST. THUS...EXPECT THE LAKE
EFFECT TO TO CONTINUE TO INCREASE IN INTENSITY/COVERAGE FOR BOTH
WEST/EAST THROUGH THE MORNING HOURS FOR LOCATIONS FAVORED BY
NORTH-NORTHWEST WINDS. WITH MUCH OF THE CONVECTIVE PORTION OF THE
CLOUD WITHIN THE DGZ...EXPECT VERY FLUFFY LAKE EFFECT AND SNOW
RATIOS IN THE 30-1 RANGE. THIS WILL ALLOW FOR QUICK ACCUMULATIONS IN
THE STRONGER BANDS...ESPECIALLY SINCE WINDS WILL HAVE DECREASED FROM
THE 20-30KTS SEEN AROUND MIDNIGHT. ONE ITEM OF CONCERN FOR THE
INTENSITY THIS MORNING OVER THE WEST...ESPECIALLY OVER THE
KEWEENAW...IS THE 30 DEGREES OF SHEAR BETWEEN THE TOP OF THE
INVERSION /800MB/ AND THE MIDDLE OF THE CONVECTIVE CLOUD /900MB/.
THIS MAY LIMIT THE DEEP AND ORGANIZED BANDS THAT WOULD PROMOTE VERY
HEAVY SNOW.
AS THIS SHORTWAVE DEPARTS LATE THIS MORNING AND INTO THE
AFTERNOON...WOULD THINK THE LAKE EFFECT WILL DIMINISH SOME AS
DIURNAL MIXING HELPS REDUCE THE INTENSITY OF THE BANDS OVER THE
WEST. IN ADDITION...THE DEEPER MOISTURE SLIDES MORE OVER THE EASTERN
LAKE WHILE WINDS BACK TO THE NORTHWEST. THIS WILL HELP REDUCE THE
INTENSITY OF THE BANDS SLIGHTLY...BUT THE BACKING WINDS WILL CAUSE
THE HEAVIEST SNOW TO SHIFT FROM THE MORE NNW FAVORED AREAS TO NW
AREAS. ALTHOUGH THIS WILL SPREAD THE LAKE EFFECT TO MORE AREAS...IT
MIGHT CAUSE SOME LIMITATION IN THE HIGHER SNOWFALL AMOUNTS IN ONE
LOCATION TO BE PRIMARILY IN THE ADVISORY CRITERIA CATEGORY. HIGHER
RESOLUTION MODELS DO PICK UP ON BOTH OF THESE FEATURES WELL AND
WILL FOLLOW THEIR TIMING FOR THE MOVEMENT AND INTENSITY FOR THIS
AFTERNOON. OVER THE EAST...INVERSION HEIGHTS OVER THE EAST RISE TO
8-10KFT THIS AFTERNOON AND CONTINUE INTO THE EVENING. WITH THE
DEEPER MOISTURE FROM THE SHORTWAVE AND SOME ENHANCED CONVERGENCE ON
THE SOUTHWEST EDGE OF THE LAKE EFFECT...EXPECT A FAIRLY HEAVY BAND
OR TWO WITHIN THE MULTI-BAND SNOW TO SETUP SOMEWHERE BETWEEN
MUNISING AND GRAND MARAIS. THIS NW WIND WILL ALSO LEAD TO
AN INCREASED PERIOD OF SNOW FOR NORTHERN LUCE COUNTY LATER THIS
AFTERNOON AND INTO THE EARLY EVENING. THIS IS DUE TO THE LONGER
FETCH THAN THEY WILL SEE FOR THE FIRST PART OF TODAY WITH THE
NORTHERLY WINDS. THERE IS THE POTENTIAL FOR SOME HEAVIER SNOWFALL
RATES AND ADVISORY SNOWFALL DURING THAT PERIOD...SO FELT
COMFORTABLE ISSUING AN ADVISORY EVEN THOUGH THERE IS SOME CONCERN
ON THE TIMING OF WHEN THE BAND WILL BACK TO THE WEST TONIGHT AS
WINDS SHIFT TO THE NORTHEAST.
COLDER AIR ARRIVES TONIGHT...WITH 850MB TEMPS FALLING TOWARDS -22C
OVER THE WEST AND -20C OVER THE EAST. OVER THE WEST...THE PRODUCES
SOME CONCERN AS IT WILL PUT A PORTION OF THE CONVECTIVE CLOUD LAYER
AT THE TOP OF OR ABOVE THE DGZ AND LIKELY REDUCE THE SNOW RATIOS
SOMEWHAT. BUT INCREASED CONVERGENCE AS WINDS VEER TO A MORE
NORTHERLY DIRECTION DURING THE EVENING...DUE TO THE APPROACHING HIGH
IN THE NORTHERN PLAINS...WILL HELP INCREASE THE
INTENSITY OF THE SNOW BEFORE RETURNING TO MORE OF A GENERAL
MULTI-BAND LAKE EFFECT DURING THE OVERNIGHT HOURS. ALSO...ANOTHER
WEAK SHORTWAVE IN THE UPPER TROUGH WILL HELP INCREASE MOISTURE AND
KEEP INVERSION HEIGHTS IN THE 7-8KFT RANGE.
OVER THE EAST...THERE DOES SEEM TO BE A SLIGHT SLOWDOWN TO THE
WESTWARD TRANSITION OF THE LAKE EFFECT FROM THE NORTHWEST FAVORED
AREAS TO MORE NORTHERLY COMPARED TO 24HRS AGO...AS THE SURFACE
TROUGH OVER EASTERN LAKE SUPERIOR WEAKENS AND LAND BREEZE INFLUENCES
OFF ONTARIO TAKE OVER. SOME OF THE HIGHER RESOLUTION MODEL RUNS EVEN
TRY TO DEVELOP A WEAK MESO-LOW...WHICH WOULD COMPLICATE MATTERS
FURTHER. THUS...HAVE SLOWED THE WESTWARD TRANSITION A TOUCH AS THE
STRONGER BANDS MAKE THE WESTWARD TRACK ACROSS ALGER AND NORTHERN
SCHOOLCRAFT COUNTIES DURING THE NIGHT. THE INCREASED CONVERGENCE
WITHIN THIS BAND SHOULD LEAD TO SOME HEAVY SNOWFALL RATES AS IT
TRANSITIONS TO THE WEST.
ALL IN ALL...WILL LEAVE THE WARNING HEADLINES AS IS AND ADD
THE LUCE ADVISORY. THERE IS SOME SLIGHT CONCERN ON GETTING WARNING
AMOUNTS IN A WIDESPREAD AREA OF GOGEBIC/ONTONAGON
COUNTIES...BUT SHOULD EASILY SEE THE 12 INCHES IN 24HRS OVER
THE PORKIES. THE ONE QUESTION TO CARRY FORWARD TO THE DAY SHIFT IS
THE BORDERLINE ADVISORY SNOW FOR NORTHERN HOUGHTON AND KEWEENAW
COUNTIES. DIDN/T HAVE A GOOD FEELING ON ADVISORY AMOUNTS FOR
TODAY...ALTHOUGH WITH THE FLUFFY NATURE...COULD SEE A QUICK 4 INCHES
IN A LOCATION IF A BAND SETS UP FOR A FEW HOURS THIS MORNING. IN
ADDITION...WITH THE WINDS BACKING TO THE NW THIS AFTERNOON AND THEN
MORE OUT OF THE NORTH TONIGHT...WOULDN/T THINK THEY WOULD SEE A
PERSISTENT AREA OF TO RAISE CONFIDENCE ENOUGH FOR AN ADVISORY AT
THIS TIME. WITH THE MORE FAVORABLE MOISTURE TONIGHT AND SOME
ENHANCED CONVERGENCE...WOULD THINK THE BEST POTENTIAL FOR ADVISORY
SNOW WOULD BE OVER NORTHERN HOUGHTON COUNTY TOWARDS TWIN LAKES AND
THE DAY SHIFT MAY NEED TO SEE IF THAT IDEA CONTINUES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 458 AM EST FRI FEB 15 2013
SATURDAY...HIGHER RES MODELS SUGGEST THAT LAKE INDUCED TROUGHING WILL
FOCUS STRONGEST LOW LEVEL CONV AND LES INTO NORTH CENTRAL UPPER MI
BTWN MARQUETTE AND MUNISING. CONTINUED HIGH SLR NEAR 30/1 WOULD
SUPPORT SOME SNOW TOTALS IN THE 4 TO 7 INCH RANGE. CONFIDENCE IN THE
LOCATION OF THIS MESO SCALE FEATURE IS LIMITED BUT A HEADLINE FOR THE FAR
EASTERN PORTION OF MARQUETTE COUNTY MAY BE NECESSARY IF MODEL
AGREEMENT IS CONSISTENT. OVER THE WEST...LES WILL DIMINISH MORE
QUICKLY WITH THE SFC RIDGE AND DRIER AIR BUILDING INTO THE AREA
LEADING TO ADDITIONAL TOTALS ONLY IN THE 1 TO 4 INCH RANGE. A SHALLOW
DGZ WITH LESS FAVORABLE SLR WOULD ALSO LIMIT ACCUMULATION POTENTIAL.
SAT NIGHT...ALTHOUGH LES WILL CONTINUE TO DIMINISH WITH THE RIDGE
BUILDING INTO THE AREA...LIGHT WIND FIELDS AND CONTINUED LOW LEVEL
CONV...ESPECIALLY NEAR THE SHORELINE VCNTY KP53 COULD PRODUCE
SEVERAL ADDITIONAL INCHES OF SNOW. OTHERWISE...CLEARING WITH
FAVORABLE RADIATIONAL COOLING CONDITIONS WILL SUPPORT MIN TEMPS NEAR
THE LOWER END OF GUIDANCE...INTO THE -15F TO -20F RANGE INTERIOR
WEST HALF.
SUN AND SUN NIGHT...A PROGRESSIVE PATTERN WITH THE SFC RIDGE
SHIFTING TO THE EAST...A TROUGH INTO THE NRN PLAINS TO THE UPPER MS
VALLEY AND A STRENGTHENING WAA PATTERN WILL ALLOW MOISTURE TO
INCREASE. BOTH THE GFS AND ECMWF SUGGEST THE STRONGEST ISENTROPIC
LIFT WILL REMAIN NORTH OF THE CWA WITH ONLY CHANCE POPS FOR LIGHT
SNOW BY LATE SUN NIGHT.
MON INTO MON NIGHT...MODELS WERE SIMILAR WITH A MID/UPPER LEVEL
TROUGH INTO THE WRN GREAT LAKES. THE ECMWF WAS A BIT SLOWER AND MORE
AGGRESSIVE IN DIGGING THE TROUGH AND SFC LOW TO THE SOUTH COMPARED
TO THE GFS...BUT NOT AS MUCH AS THE CMC...RESULTING IN GREATER PCPN
ACROSS UPPER MICHIGAN. WITH SUFFICIENT MOISTURE INFLOW BRINGING PWAT
TO NEAR 200 PCT NORMAL THE POTENTIAL REMAINS FOR MODERATE SNOW
ACCUMULATIONS WITH THE SYSTEM.
TUE-WED...SIGNFICANT/HEAVY LES WILL BE POSSIBLE IN THE WAKE OF THE
LOW WITH STRONG CAA DROPPING 850 MB TEMPS INTO THE -15C TO -20C
RANGE ALONG WITH CYCLONIC NNW FLOW AND ABUNDANT 850-700
MOISTURE...PER ECMWF. LES SHOULD DIMINISH WED AS RIDGING AGAIN
BUILDS INTO THE REGION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1232 AM EST FRI FEB 15 2013
ARRIVAL OF DRIER/MORE STABLE AIRMASS SHOWN ON THE 12Z INL RAOB HAS
CAUSED THE LES TO DIMINISH AT THE TAF SITES EARLY THIS MRNG...WITH
VFR/HIER END MVFR CONDITIONS THE RULE AT TAF ISSUANCE. BUT EXPECT AN
UPTICK IN LES INTENSITY BY 12Z MAINLY AT IWD WITH SHARPER LLVL CNVGC
AND MORE FVRBL UPSLOPE NNW FLOW AS COLDER AIR AS WELL AS MORE MID
LVL MSTR SHOWN ON THE 00Z INL RAOB AND UPSTREAM SFC OBS MOVE ACRS
THE LK. SINCE THE FLOW AT CMX WL NOT AS FVRBL THRU MUCH OF TODAY...
MVFR CONDITIONS SHOULD BE THE RULE THERE. IFR WX MAY DVLP BY THIS
EVNG AT THAT SITE WITH SHARPENING LLVL CNVGC. GENERAL DOWNSLOPE WIND
COMPONENT THRU THE FCST PERIOD AT SAW SHOULD MAINTAIN PREDOMINANT
VFR TO OCNL HIER END MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 AM EST FRI FEB 15 2013
NORTHWEST WINDS OF 20-30KTS WILL DIMINISH TODAY AS HIGH PRESSURE IN
THE NORTHERN PLAINS SLOWLY SHIFTS EAST INTO THE UPPER GREAT LAKES.
THIS WILL CONTINUE TO DIMINISH THE WINDS ON THROUGH SATURDAY.
BEFORE THE WINDS DIMINISH...HEAVY FREEZING SPRAY IS EXPECTED OVER
PORTIONS OF LAKE SUPERIOR THROUGH TONIGHT. AS THE HIGH SHIFTS EAST
ON SUNDAY A LOW PRESSURE SYSTEM WILL APPROACH THE UPPER GREAT LAKES
ON MONDAY AND MOVE THROUGH ON TUESDAY. THIS WILL BRING INCREASING
SOUTHERLY FLOW ON MONDAY...TO 25KTS OVER THE EAST...AND THEN STRONG
NORTHERLY WINDS BEHIND THE LOW ON TUESDAY AFTERNOON...TO 30KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SATURDAY FOR MIZ006-085.
LAKE EFFECT SNOW ADVISORY UNTIL 5 AM EST SATURDAY FOR MIZ007.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST /NOON CST/ SATURDAY FOR
MIZ002-009.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR
LSZ264>266.
HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR
LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...JLB
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
921 AM CST FRI FEB 15 2013
.UPDATE...
ISSUED AT 919 AM CST FRI FEB 15 2013
UPDATED FORECAST TO REMOVE FLURRIES AND CLEAR SKIES FOR TODAY.
CVKING
&&
.SHORT TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TODAY)
EARLY MORNING RUC ANALYSES OF THE 1.5 PVU SFC COMBINED WITH WATER
VAPOR IMAGERY DEPICTED A REASONABLY STRONG PV ANOMALY MOVING ACROSS
NRN MO. THIS FEATURE IS EXPECTED TO CONTINUE MOVING ACROSS THE AREA
TODAY WITHIN A BROADER PATTN OF NW FLOW ALOFT. DESPITE THE PRESENCE
OF A FORCING MECHANISM...THE LIMITING FACTOR FOR MEASURABLE PCPN
TODAY WILL BE MOISTURE GIVEN THE FAIRLY DRY LOW AND MID LEVELS AS
WELL AS DECREASING PW VALUES THROUGH THE DAY. AT THE SFC...A CDFNT
WAS LOCATED FM CENTRAL KS THROUGH NRN MO INTO NRN IL AT 06Z. THIS
FRONT WILL CONTINUE MOVING SEWD TODAY...LEADING TO A COMPLICATED
FCST OF TEMPERATURE TRENDS DUE TO THE COMPETING FACTORS OF LOW LEVEL
CAA...POTENTIAL MIXING ABOVE 900 MB...AND THE EFFECTS OF POSTFRONTAL
CLOUDINESS DURING THE LATE MORNING FOLLOWED BY ADDITIONAL CLOUDS
ADVECTING SWD DURING THE LATE AFTN.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TONIGHT THROUGH SUNDAY)
SHORT RANGE MODELS ARE MAINTAINING GOOD RUN TO RUN CONTINUITY
WITH SYNOPTIC FEATURES HEADING INTO THE WEEKEND. ANOTHER SHORTWAVE
WILL DROP SOUTH ACROSS THE PLAINS TONIGHT ON THE BACK SIDE OF THE
UPPER LEVEL TROF...BRINGING A REINFORCING SHOT OF COLD AIR TO THE
AREA FOR SATURDAY. DYNAMICS WITH THIS FEATURE SHOULD CONFINE ANY
PRECIP THREAT TO THE WEST OF OUR CWA...BUT WITH DIRTY NW FLOW AND
MEAN TROF AXIS REMAINING PARKED OVER AREA WE SHOULD CERTAINLY SEE
SOME CLOUDINESS OVERNIGHT AND AT LEAST INTO SATURDAY MORNING.
TEMPERATURE TRENDS IN GOING FORECAST STILL LOOK PRETTY GOOD. THIS
AMS IS FAIRLY CHILLY BUT DUE TO THE EXPECTED CLOUDS OVERNIGHT I HAVE
FOUGHT THE TEMPTATION TO GO TOO COLD...AND STILL HAVE LOWS IN THE
UPPER TEENS TO LOWER 20S. HIGHS SHOULD REBOUND INTO THE L-M30S ON
SATURDAY.
TROF IS STILL ON SCHEDULE TO SWING INTO THE EASTERN U.S. ON SUNDAY.
THIS WILL ALLOW A RAPID TEMPERATURE MODERATION OVER THE CWA...
WITH HIGHS RANGING FROM THE MID 40S OVER OUR E COUNTIES...TO THE
MID 50S OVER MID MO.
(MONDAY-THURSDAY)
ITS PROBABLY A BIT OF AN UNDERSTATEMENT TO SAY THAT THE UA PATTERN
OVER THE CONUS WILL BE ACTIVE FOR MUCH OF NEXT WEEK...WITH THE VERY
AMPLIFIED AND PROGRESSIVE PATTERN PROGGED TO BRING TWO STORM
SYSTEMS INTO THE CENTRAL U.S. MEDIUM RANGE SOLUTIONS ARE
REMAINING IN REMARKABLE RUN TO RUN AND MODEL TO MODEL AGREEMENT
WITH THE TIMING OF THESE SYSTEMS...WITH THE FIRST IMPACTING THE
REGION ON MONDAY AND MONDAY NIGHT AND THE SECOND...AND PROBABLY
STRONGER...SYSTEM ARRIVING LATE WEDNESDAY AND THURSDAY.
MONDAY AND MONDAY NIGHT`S SYSTEM WILL PRIMARILY BE A RAIN
EVENT...WITH THE BULK OF THE PRECIP SHUTTING DOWN ON MONDAY NIGHT
WITH THE ARRIVAL OF THE COLD AIR PREVENTING ANY SIGNIFICANT PERIOD
OF SNOWFALL. SOLUTIONS HAVE NOT BACKED OFF OF THE THINKING THAT
MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM AND DYNAMICS WILL BE
STRONG...SO LIKELY POPS OVER MOST OF THE CWA STILL LOOK LIKE A GOOD
CALL.
ANOTHER SHOT OF COLD AIR IN THE WAKE OF MONDAY`S SYSTEM WILL DROP
TEMPS BACK TO BELOW AVERAGE LEVELS FOR TUESDAY AND WEDNESDAY...AND
THIS COLD AIR WILL SET THE STAGE FOR THE BIG QUESTION MARK FOR
THURSDAY`S SYSTEM...WHICH IS PTYPE. IT CERTAINLY APPEARS THAT THE
FIRST SHOT OF PRECIP INTO THE AREA LATE WEDNESDAY NIGHT AND THURSDAY
MORNING ASSOCIATED WITH INITIAL SURGE OF WARM ADVECTION WILL LIKELY
BE SNOW...BUT PRIMARY QUESTION IS WHAT PTYPES WILL DO DURING THE DAY
ON THURSDAY. OPERATIONAL GFS AND ECMWF ARE BOTH PROGGING VERY
STRONG 850 WAA INTO THE CWA BUT 850 TEMPS...ON BOTH SOLUTIONS...
APPEAR TO BE VERY RELUCTANT TO WARM DURING THE DAY. THIS TREND
LOOKS TO BE TOO COLD GIVEN PLACEMENT OF 850 LOW AND STRENGTH OF
WAA....BUT IT IS PROBABLY A STRONG SIGNAL THAT BOTH MODELS ARE
SUGGESTING THAT THE EVAPORATIVE COOLING THAT DEVELOPS WITH THE
ONSET OF PRECIP WILL BE TOUGH TO OVERCOME.
IF THE CONSENSUS OF THESE SOLUTIONS AND THE LATEST GFS ENSEMBLE
VERIFY...PTYPE WOULD BE ALL SNOW IN THE FAR NORTH AND ALL RAIN IN
THE FAR SOUTH...BUT OVER MOST OF THE CWA PTYPE COULD GO EITHER
WAY. AS MENTIONED BY THE DAY SHIFT YESTERDAY PTYPE FORECASTS WILL
LIKELY BE CHANGING SEVERAL TIMES AS THE EVENT GETS CLOSER IN
TIME...AND SINCE THE STORM IS STILL 7 DAYS OUT WILL MAINTAIN A
BROAD BRUSH APPROACH FOR PTYPE.
TRUETT
&&
.AVIATION...
ISSUED AT 548 AM CST FRI FEB 15 2013
SCT-BKN MVFR CLOUDS INVOF A CDFNT SHOULD MOVE SOUTH AND EAST OF
THE TERMINALS THIS MORNING. SCT FLURRIES ARE POSSIBLE HOWEVER NO
VIS RESTRICTIONS ARE ANTICIPATED. WINDS WILL REMAIN NWLY THROUGH
THE PD. ADDITIONAL CLOUDS SHOULD REDEVELOP TONIGHT AHEAD OF AN
APPROACHING UPPER LEVEL DISTURBANCE HOWEVER IT APPEARS THAT CIGS
WILL REMAIN VFR TONIGHT DUE TO LIMITED MOISTURE IN THE ATMOSPHERE.
SPECIFICS FOR KSTL...SCT-BKN MVFR CLOUDS INVOF A CDFNT SHOULD MOVE
SOUTH AND EAST OF KSTL THIS MORNING. SCT FLURRIES ARE POSSIBLE
HOWEVER NO VIS RESTRICTIONS ARE ANTICIPATED. WINDS WILL REMAIN
NWLY THROUGH THE PD.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
609 AM CST FRI FEB 15 2013
.SHORT TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TODAY)
EARLY MORNING RUC ANALYSES OF THE 1.5 PVU SFC COMBINED WITH WATER
VAPOR IMAGERY DEPICTED A REASONABLY STRONG PV ANOMALY MOVING ACROSS
NRN MO. THIS FEATURE IS EXPECTED TO CONTINUE MOVING ACROSS THE AREA
TODAY WITHIN A BROADER PATTN OF NW FLOW ALOFT. DESPITE THE PRESENCE
OF A FORCING MECHANISM...THE LIMITING FACTOR FOR MEASURABLE PCPN
TODAY WILL BE MOISTURE GIVEN THE FAIRLY DRY LOW AND MID LEVELS AS
WELL AS DECREASING PW VALUES THROUGH THE DAY. AT THE SFC...A CDFNT
WAS LOCATED FM CENTRAL KS THROUGH NRN MO INTO NRN IL AT 06Z. THIS
FRONT WILL CONTINUE MOVING SEWD TODAY...LEADING TO A COMPLICATED
FCST OF TEMPERATURE TRENDS DUE TO THE COMPETING FACTORS OF LOW LEVEL
CAA...POTENTIAL MIXING ABOVE 900 MB...AND THE EFFECTS OF POSTFRONTAL
CLOUDINESS DURING THE LATE MORNING FOLLOWED BY ADDITIONAL CLOUDS
ADVECTING SWD DURING THE LATE AFTN.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TONIGHT THROUGH SUNDAY)
SHORT RANGE MODELS ARE MAINTAINING GOOD RUN TO RUN CONTINUITY
WITH SYNOPTIC FEATURES HEADING INTO THE WEEKEND. ANOTHER SHORTWAVE
WILL DROP SOUTH ACROSS THE PLAINS TONIGHT ON THE BACK SIDE OF THE
UPPER LEVEL TROF...BRINGING A REINFORCING SHOT OF COLD AIR TO THE
AREA FOR SATURDAY. DYNAMICS WITH THIS FEATURE SHOULD CONFINE ANY
PRECIP THREAT TO THE WEST OF OUR CWA...BUT WITH DIRTY NW FLOW AND
MEAN TROF AXIS REMAINING PARKED OVER AREA WE SHOULD CERTAINLY SEE
SOME CLOUDINESS OVERNIGHT AND AT LEAST INTO SATURDAY MORNING.
TEMPERATURE TRENDS IN GOING FORECAST STILL LOOK PRETTY GOOD. THIS
AMS IS FAIRLY CHILLY BUT DUE TO THE EXPECTED CLOUDS OVERNIGHT I HAVE
FOUGHT THE TEMPTATION TO GO TOO COLD...AND STILL HAVE LOWS IN THE
UPPER TEENS TO LOWER 20S. HIGHS SHOULD REBOUND INTO THE L-M30S ON
SATURDAY.
TROF IS STILL ON SCHEDULE TO SWING INTO THE EASTERN U.S. ON SUNDAY.
THIS WILL ALLOW A RAPID TEMPERATURE MODERATION OVER THE CWA...
WITH HIGHS RANGING FROM THE MID 40S OVER OUR E COUNTIES...TO THE
MID 50S OVER MID MO.
(MONDAY-THURSDAY)
ITS PROBABLY A BIT OF AN UNDERSTATEMENT TO SAY THAT THE UA PATTERN
OVER THE CONUS WILL BE ACTIVE FOR MUCH OF NEXT WEEK...WITH THE VERY
AMPLIFIED AND PROGRESSIVE PATTERN PROGGED TO BRING TWO STORM
SYSTEMS INTO THE CENTRAL U.S. MEDIUM RANGE SOLUTIONS ARE
REMAINING IN REMARKABLE RUN TO RUN AND MODEL TO MODEL AGREEMENT
WITH THE TIMING OF THESE SYSTEMS...WITH THE FIRST IMPACTING THE
REGION ON MONDAY AND MONDAY NIGHT AND THE SECOND...AND PROBABLY
STRONGER...SYSTEM ARRIVING LATE WEDNESDAY AND THURSDAY.
MONDAY AND MONDAY NIGHT`S SYSTEM WILL PRIMARILY BE A RAIN
EVENT...WITH THE BULK OF THE PRECIP SHUTTING DOWN ON MONDAY NIGHT
WITH THE ARRIVAL OF THE COLD AIR PREVENTING ANY SIGNIFICANT PERIOD
OF SNOWFALL. SOLUTIONS HAVE NOT BACKED OFF OF THE THINKING THAT
MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM AND DYNAMICS WILL BE
STRONG...SO LIKELY POPS OVER MOST OF THE CWA STILL LOOK LIKE A GOOD
CALL.
ANOTHER SHOT OF COLD AIR IN THE WAKE OF MONDAY`S SYSTEM WILL DROP
TEMPS BACK TO BELOW AVERAGE LEVELS FOR TUESDAY AND WEDNESDAY...AND
THIS COLD AIR WILL SET THE STAGE FOR THE BIG QUESTION MARK FOR
THURSDAY`S SYSTEM...WHICH IS PTYPE. IT CERTAINLY APPEARS THAT THE
FIRST SHOT OF PRECIP INTO THE AREA LATE WEDNESDAY NIGHT AND THURSDAY
MORNING ASSOCIATED WITH INITIAL SURGE OF WARM ADVECTION WILL LIKELY
BE SNOW...BUT PRIMARY QUESTION IS WHAT PTYPES WILL DO DURING THE DAY
ON THURSDAY. OPERATIONAL GFS AND ECMWF ARE BOTH PROGGING VERY
STRONG 850 WAA INTO THE CWA BUT 850 TEMPS...ON BOTH SOLUTIONS...
APPEAR TO BE VERY RELUCTANT TO WARM DURING THE DAY. THIS TREND
LOOKS TO BE TOO COLD GIVEN PLACEMENT OF 850 LOW AND STRENGTH OF
WAA....BUT IT IS PROBABLY A STRONG SIGNAL THAT BOTH MODELS ARE
SUGGESTING THAT THE EVAPORATIVE COOLING THAT DEVELOPS WITH THE
ONSET OF PRECIP WILL BE TOUGH TO OVERCOME.
IF THE CONSENSUS OF THESE SOLUTIONS AND THE LATEST GFS ENSEMBLE
VERIFY...PTYPE WOULD BE ALL SNOW IN THE FAR NORTH AND ALL RAIN IN
THE FAR SOUTH...BUT OVER MOST OF THE CWA PTYPE COULD GO EITHER
WAY. AS MENTIONED BY THE DAY SHIFT YESTERDAY PTYPE FORECASTS WILL
LIKELY BE CHANGING SEVERAL TIMES AS THE EVENT GETS CLOSER IN
TIME...AND SINCE THE STORM IS STILL 7 DAYS OUT WILL MAINTAIN A
BROAD BRUSH APPROACH FOR PTYPE.
TRUETT
&&
.AVIATION...
ISSUED AT 548 AM CST FRI FEB 15 2013
SCT-BKN MVFR CLOUDS INVOF A CDFNT SHOULD MOVE SOUTH AND EAST OF
THE TERMINALS THIS MORNING. SCT FLURRIES ARE POSSIBLE HOWEVER NO
VIS RESTRICTIONS ARE ANTICIPATED. WINDS WILL REMAIN NWLY THROUGH
THE PD. ADDITIONAL CLOUDS SHOULD REDEVELOP TONIGHT AHEAD OF AN
APPROACHING UPPER LEVEL DISTURBANCE HOWEVER IT APPEARS THAT CIGS
WILL REMAIN VFR TONIGHT DUE TO LIMITED MOISTURE IN THE ATMOSPHERE.
SPECIFICS FOR KSTL...SCT-BKN MVFR CLOUDS INVOF A CDFNT SHOULD MOVE
SOUTH AND EAST OF KSTL THIS MORNING. SCT FLURRIES ARE POSSIBLE
HOWEVER NO VIS RESTRICTIONS ARE ANTICIPATED. WINDS WILL REMAIN
NWLY THROUGH THE PD.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1058 AM EST FRI FEB 15 2013
.SYNOPSIS...
A WEAK CLIPPER WILL PASS TO THE NORTH OF THE STATE TODAY. THE
TRAILING FRONT OVER THE VIRGINIAS WILL SPAWN A WEAK WAVE THAT
COULD SPREAD SOME RAIN AND SNOW OVER THE SOUTHEASTERN PARTS OF THE
REGION LATER TODAY AND TONIGHT.
A COLD NORTHWEST FLOW WILL PREVAIL FOR THE REMAINDER OF THE
WEEKEND WITH SCATTERED LAKE EFFECT SNOW SHOWERS AND FLURRIES. SOME
MODERATION IN TEMPERATURES IS EXPECTED EARLY NEXT WEEK WITH ANOTHER
FRONTAL SYSTEM EXPECTED TO APPROACH BY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATYEST NAM AND SREF 09Z RUNS HAVE NUDGED PRECIP ACCUMS HIGHER
THAN PREV SOLNS. HRRR AND NEWEST RUC SUPPORT THE EVOLUTION IN NAM
STYLE ALSO. WILL NUDGE SNOW ACCUMS UP JUST ABOUT 50PCT FOR THE
EVENING...BUT HOLD OFF ON ENOUGH OF A BUMP TO PASS THOUGH THE ADVY
THRESHOLD. KEEPING FCST DOWN AT 1-3 INCHES FOR YORK AND LANCASTER
COS. OTHERWISE NO CHANGES.
THE BIGGEST SHORT TERM FORECAST PROBLEM WILL CENTER ON A WAVE OF
LOW PRESSURE THAT THE MODELS WANT TO SEE DEVELOP ALONG THE WEAK
FRONT THAT WILL BE MOVING THROUGH VIRGINIA. THE GFS IS THE MOST
AGGRESSIVE SNOW MAKER WITH THIS SYSTEM...IMPLYING THAT ADVISORY
SNOWS ARE POSSIBLE OVER THE LOWER SUSQ VALLEY FROM ABOUT ADAMS
COUNTY EASTWARD. THE GEFS IS TAMER...WITH AN INCH OR TWO INDICATED
IN THE THREATS OUTPUT. THE SREF SIMILARLY DOWNPLAYS THE SNOW
POTENTIAL...WHICH ALSO MATCHES THE OPERATIONAL ECMWF. ALL OF WHICH
SHOW THAT DESPITE IT BEING COLD ENOUGH ALOFT...SKIN TEMPS OVER THE
SE WILL BE INITIALLY PRETTY WARM IMPLYING THAT EVEN IF SNOW IS THE
PREDOM PRECIP TYPE...MELTING WILL KEEP NUMBERS DOWN.
HIGHS NEAR FREEZING OVER THE NW TODAY WILL ACTUALLY BE VERY CLOSE
TO MID FEB NORMALS...WHILE TEMPS APPROACHING 50 OVER THE SE WILL
BE MORE LIKE 5 TO 10 DEG ABOVE NORMAL.
TIMING OF THE PRECIP LOOKS LIKE THINGS WILL WIND DOWN DURING THE
EVENING WITH LITTLE MORE BUT SOME LINGERING LIGHT SNOW OR FLURRIES
LEFTOVER AFTER MIDNIGHT. LOWS WILL DROP BACK INTO THE TEENS OVER
THE NW...TO NEAR FREEZING OVER THE SE.
&&
.SHORT TERM /SATURDAY/...
AN UPPER TROUGH/LOW WILL CONTINUE THE PROGRESS OF DEEPENING DOWN
INTO THE EASTERN GR LAKES...HELPING DELIVER A LATE WINTER SHOT OF
ARCTIC AIR. IT DOESN`T LOOK LIKE THE COLDEST AIR WE HAVE
EXPERIENCED THIS WINTER...BUT IT WILL CHILL US DOWN BACK BELOW
NORMAL NONE THE LESS.
PRECIP WILL BE ON THE LIGHT SIDE AND MAINLY CONFINED TO THE USUAL
PARTS OF THE STATE FAVORED BY POST FRONTAL LOW LEVEL COLD
ADVECTION SNOW SHOWERS. EXPECT ACCUMULATIONS TO BE LIGHT OVER THE
NW AS LOW LEVEL WINDS WILL INITIALLY NOT ATTAIN A FAVORABLE OVER-
LAKE TRAJECTORY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE UPPER TROUGH IS FCST TO DEEPEN AND CLOSE OFF TO A TIDY UPPER
LOW OVER OR JUST NORTH OF PA DURING THE DAY SUNDAY. THE VARIOUS
OPERATIONAL MODELS USE THIS DEEPENING SYSTEM ALOFT TO DEVELOP
ANOTHER LOW ALONG THE FRONT ALONG OR JUST OFF THE EAST COAST. THE
GFS/ECMWF ACTUALLY SHOW THE PRECIP BRUSHING THE EAST
COAST...POSSIBLY JUST NUDGING INTO MY SERN ZONES A BIT WITH LIGHT
AMOUNTS SUNDAY. THE GEFS LOOKS MORE REASONABLE HOWEVER KEEPING
PRECIP OUT OF MY FCST AREA AND MAINLY OFFSHORE. SO SUNDAY I KEPT
THE FCST DRY EXCEPT FOR THE USUAL WESTERN SNOW SHOWERS.
THE NEXT SYSTEM OF NOTE LOOKS TO ARRIVE ON TUESDAY. AS THE HIGH
SLIDES OFF TO OUR EAST...WE SHOULD SEE WARM AIR FLOOD BACK INTO
THE REGION MAKING FOR MAINLY A RAIN EVENT WITH THE APPROACHING
FRONT. HOWEVER WE WILL HAVE TO WATCH FOR THE POTENTIAL OF A WINTRY
MIX AT THE ONSET IF THE PRECIP ARRIVES EARLY ENOUGH TUESDAY.
IT WILL COOL DOWN ONCE AGAIN BEHIND THE FRONT FOR MID
WEEK...BEFORE MILDER AIR STARTS TO MOVE BACK TOWARD THE REGION
LATE IN THE WEEK. THE PATTERN IS COMPLICATED HOWEVER WITH MODELS
HINTING AT AN UPPER BLOCK DEVELOPING OVER SOUTHERN CANADA. THIS
COULD SUPPRESS THE WARM AIR AND KEEP US JUST COLD ENOUGH THAT ANY
MOISTURE THAT HEADS OUR WAY COULD CREATE THE POTENTIAL FOR SNOW OR
A WINTRY MIX BY WEEK`S END.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
NO MAJOR CHANGES MADE TO 12Z TAF PACKAGE.
EARLIER DISCUSSION BELOW.
A LOW PRES SYSTEM TRACKING NORTH OF PA THROUGH THE GRT LKS WILL
DRAG A WEAK COLD FRONT ACROSS THE REGION THIS MORNING. MOST OF
THE LOWER CIGS WILL BE ACROSS THE WESTERN PART OF THE STATE.
OTHER THAN BFD AND JST...AND TIMES AOO...MOST AREAS WILL BE VFR
TODAY. SOME HINTS THAT CONDITIONS COULD BE MVFR AT TIMES BY LATE
AFTERNOON AND THIS COULD LINGER INTO TONIGHT...AS A WEAK WAVE
FORMS ON THE FRONT AND LIFTS NE.
HINTS THAT THIS COULD OCCUR AGAIN LATE FRIDAY...AND AGAIN
LATER ON SAT. THE SYSTEM FOR FRIDAY NIGHT WOULD MOST LIKELY
BE THE STRONGER ONE...COMPARED TO THE ONE LATE THU...OR ON
SAT.
COLDER AND MORE WIND FOR THE WEEKEND.
IMPROVING CONDITIONS FOR MONDAY...AS HIGH PRESSURE BUILDS
NORTHWARD.
SOME SHOWERS ON TUE...AS NEXT COLD FRONT MOVES TOWARD THE
AREA.
OUTLOOK...
SAT...SHSN/REDUCED VSBYS POSSIBLE W MTNS...ESP LATE.
SUN...BREEZY WITH SHSN POSSIBLE...MAINLY W MTNS.
MON...NO SIG WX EXPECTED.
TUE...SHRASN/REDUCED CIGS POSSIBLE...MAINLY W MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...DANGELO/LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
329 PM MST FRI FEB 15 2013
.SHORT TERM...WEAK SHORTWAVE IN NORTHWEST FLOW ALOFT CLIPPING
NORTHEAST PLAINS OF COLORADO AT PRESENT TIME. RADAR INDICATING A
FEW LIGHT SHOWERS MOVING SOUTHEAST ACROSS WASHINGTON AND ELBERT
COUNTIES ON BACK EDGE OF THE MID LEVEL ASCENT. DOESN`T APPEAR MUCH
IS REACHING THE GROUND BASED ON WEB CAMS AND SURFACE OBS. ENOUGH
MIXING BEHIND SURGE HAS HELPED TO PRODUCE GUSTY WINDS ACROSS MUCH
OF PLAINS WITH SOME GUSTS NEAR 40 MPH FROM DENVER NORTH TOWARD THE
WYOMING BORDER. OVER THE MOUNTAINS...WEB CAMS STILL SHOWING LIGHT
SNOW ALONG THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES...
THOUGH HAS BEEN SHOWING SIGNS OF DECREASING DURING THE PAST
COUPLE OF HOURS. GUSTY WINDS ALSO OCCURRING ACROSS THE MOUNTAINS
AND ALONG THE FOOTHILLS. LATEST RAP SHOWS MOISTURE DEPTH
DECREASING DURING THE EVENING ACROSS THE MOUNTAINS. DESPITE
CONTINUED OROGRAPHICS...SHOULD SEE SNOW DECREASE THROUGH THE
EVENING AND COME TO AN END AROUND MIDNIGHT AS MID LEVEL WARMING
INCREASES AND LAPSE RATES DECREASE. ANY ADDITIONAL ACCUMULATIONS
WILL BE LIGHT. MID LEVEL WARMING TO DEVELOP MOUNTAIN WAVE BY
MIDNIGHT. INCREASING SUBSIDENCE WILL HELP WITH DOWNWARD MOMENTUM
TO INCREASE WINDS ACROSS MOUNTAINS AND ALONG FOOTHILLS. DOES NOT
LOOK LIKE A HIGH WIND SITUATION AS CROSS MOUNTAIN FLOW EXPECTED TO
BE AROUND 40 KTS. MODELS SHOW SOME HINTS OF THE WAVE WEAKENING
AFTER MIDNIGHT...WITH PERHAPS A DECREASE IN THE SPEEDS. ACROSS THE
PLAINS...WINDS TO GRADUALLY DECREASE DURING THE EVENING AS SURFACE
GRADIENT WEAKENS...THOUGH MAY REMAIN GUSTY NEAR THE BASE OF THE
FOOTHILLS AND FAR EASTERN PLAINS. OVERNIGHT TEMPERATURES TO BE
SLIGHTLY WARMER MOST AREAS DUE TO THE WARM AIR ADVECTION AND WIND.
HOWEVER...LOW LYING AREAS BELOW THE MID LEVEL INVERSION TO BE MUCH
COLDER WITH PERHAPS BELOW ZERO READINGS IN THE VALLEYS OF GRAND
AND JACKSON COUNTIES. ON SATURDAY...NORTHWEST FLOW ALOFT TO
CONTINUE AS UPPER RIDGE BUILDS ACROSS THE GREAT BASIN...THOUGH
GRADIENT WILL BE WEAKER. SO WINDS TO BE LIGHTER...THOUGH WILL
STILL BE A BIT GUSTY ACROSS THE MOUNTAINS AND HIGHER FOOTHILLS.
SOME MIXING POSSIBLE OVER THE PLAINS COULD CREATE SOME GUSTY
NORTHWEST WINDS DURING THE AFTERNOON. HIGHS TO WARM INTO THE 50S
ACROSS THE PLAINS.
.LONG TERM...ON SATURDAY NIGHT...AN UPPER LEVEL TROUGH WILL BE OVER
THE NORTHERN ROCKIES WHILE A WEAK RIDGE MOVES ACROSS COLORADO. THIS
IS EXPECTED TO BRING DRY CONDITIONS SATURDAY NIGHT AND FOR MOST OF
SUNDAY. COULD SEE A FEW LIGHT SNOW SHOWERS LATE SUNDAY AFTERNOON
OVER THE MOUNTAINS OF NORTH CENTRAL COLORADO AS THE UPPER LEVEL
TROUGH OVER THE NORTHERN ROCKIES SHIFTS EAST-SOUTHEAST. A SURFACE
LOW WILL FORM OVER SOUTHEAST COLORADO SUNDAY IN ADVANCE OF THE
TROUGH. THIS WILL CAUSE WINDS TO TURN NORTHERLY OVER NORTHEAST
COLORADO SUNDAY AFTERNOON. EXPECT THIS TO START PULLING IN COOLER
AIR SO DROPPED HIGHS FOR SUNDAY A FEW DEGREES. HOWEVER...IT WILL
STILL BE MILD WITH HIGHS IN THE 50S.
THE BASE OF THE TROUGH WILL MOVE ACROSS WYOMING AND NORTHERN
COLORADO SUNDAY NIGHT AND EARLY MONDAY. THIS WILL LIKELY BRING A
SHOT OF LIGHT SNOW TO THE MOUNTAINS. FOR THE FRONT RANGE...NOT A
FAVORABLE SET UP BUT WINDS MAY TURN UPSLOPE FOR LONG ENOUGH TO
PRODUCE LIGHT SNOW ALONG THE FRONT RANGE. THE PLAINS MAY SEE A LIGHT
DUSTING AT BEST. SNOW MAY LINGER INTO MONDAY MORNING OVER THE
MOUNTAINS AND PALMER DIVIDE BEFORE DRIER MOVES IN FOR MONDAY
AFTERNOON.
A WEAK RIDGE WILL KEEP DRY CONDITIONS OVER COLORADO MONDAY NIGHT AND
TUESDAY. HIGHS WILL BE NEAR NORMAL TUESDAY WITH READINGS IN THE 40S.
A DEEP TROUGH WILL MOVE ONTO THE CALIFORNIA COAST TUESDAY. GENERAL
PATTERN HAS BEEN CONSISTENT FOR THE PAST FEW DAYS WITH THIS DEEP
TROUGH CLOSING OFF AND MOVING ACROSS THE GREAT BASIN AND THEN THE
ROCKIES BY MID TO LATE WEEK. DETAILS ON TRACK DEVELOPMENT STILL
NEEDS TO BE WORKED OUT. TEMPERATURES WILL BE COOL WITH MOST PLACES
SEEING PRECIPITATION SOMETIME LATE WEDNESDAY THROUGH THURSDAY. MANY
OF THE MODELS ARE SHOWING A CLOSED LOW LIFTING NORTHEAST ACROSS UTAH
ON WEDNESDAY AND THEN REFORMING THE MAIN LOW OVER SOUTHEAST COLORADO
BY THURSDAY MORNING. THIS WOULD WORK AGAINST HEAVY SNOW FOR THE
FRONT RANGE. ONCE THE LOW REFORMS OVER SOUTHEAST COLORADO...IT WILL
THEN LIFT NORTHEAST ACROSS THE CENTRAL PLAINS WHERE IT WILL LIKELY
PRODUCE BLIZZARD CONDITIONS THURSDAY AND THURSDAY NIGHT. WILL HAVE
THE HIGHEST POPS OVER THE COLORADO EASTERN PLAINS BECAUSE OF THIS.
EXPECT COOL CONDITIONS TO PREVAIL FRIDAY BECAUSE OF A LONG WAVE
TROUGH STILL OVER THE WESTERN U.S. A WEAKER TROUGH WILL BE OVER THE
GREAT BASIN FRIDAY AND WILL HAVE LOW POPS IN THE MOUNTAINS FOR THIS
SYSTEM.
&&
.AVIATION...GUSTY NORTHERLY WINDS AT DEN BEGINNING TO SHOW SOME
SIGNS OF DECREASING AND SHIFTING TO THE NORTHEAST. GRADIENT WEAKER
AND BJC AND APA. CEILINGS HAVE INCREASED TO ABOVE 7000 FEET AGL
WITH VFR PREVAILING. WINDS TO CONTINUE TO WEAKEN ACROSS THE AREA
AIRPORTS...BECOMING SOUTHEAST AROUND 03Z. SOUTHWEST DRAINAGE WINDS
TO THEN DEVELOP BY 06Z...THOUGH MAY BE MORE WESTERLY AT BJC.
POSSIBLE MOUNTAIN WAVE OVER FRONT RANGE OVERNIGHT WITH POTENTIAL
GUSTS TO 40 KTS AT BJC. WINDS TO SHIFT TO THE NORTHWEST AT 15Z
SATURDAY. SOME GUSTS TO 20 KTS POSSIBLE AT DEN. VFR TO CONTINUE
WITH UNLIMTED CEILINGS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1022 AM MST FRI FEB 15 2013
.UPDATE...
&&
.AVIATION...WILL NEED TO DELAY THE ONSET OF THE NORTHERLY WINDS
TIL 20Z BASED ON CURRENT CONDITIONS AND LATEST RAP AND HRRR
SOLUTIONS. ALL ELSE SEEM IN ORDER.
&&
.PREV DISCUSSION... /ISSUED 1017 AM MST FRI FEB 15 2013/
UPDATE...
SHORT TERM...CURRENT FORECASTS LOOK ON TRACK. PASSING SHORTWAVE
ACROSS PLAINS IN NORTHWEST FLOW PRODUCING LIGHT SNOW SHOWERS NORTH
AND EAST OF DENVER AREA. ACROSS MOUNTAINS...GOOD OROGRAPHICS
KEEPING LIGHT SNOW GOING DESPITE STRONG SUBSIDENCE AND STABILITY.
LATEST RAP CROSS SECTIONS SHOWING ANOTHER WEAK MID LEVEL SHORTWAVE
CLIPPING THE NORTHEAST CORNER DURING THE AFTERNOON WITH SOME MID
LEVEL QG ASCENT. NEARBY JET WILL HELP PRODUCE SOME SNOW SHOWERS
ACROSS THE PLAINS INTO THE EARLY EVENING. NOT EXPECTING MUCH IN
THE WAY OF ACCUMULATION WITH THE SHOWERS...THOUGH THE LIFT AND
SLIGHT COOLING WITH A FRONTAL SURGE COULD PRODUCE SOME BRIEF
ACCUMULATION WITH THE STRONGER SHOWERS. STILL EXPECTING ANY
ACCUMULATION TO BE LESS THAN AN INCH...EVEN WITH THE STRONGER
ACTIVITY. MOUNTAIN ACTIVITY TO GRADUALLY DECREASE BY THE EVENING
AS MOISTURE DEPTH DECREASES. FOR TONIGHT...DESPITE THE WARMING
ALOFT AND POTENTIAL FOR BRIEF MOUNTAIN WAVE...THREAT FOR HIGH
WINDS APPEARS LOW WITH THE GUSTY WINDS CONFINED TO THE HIGHER
RIDGES.
AVIATION...CURRENT TAF TRENDS ON TRACK WITH VFR CONDITIONS
PREVAILING. WEAK NORTHERLY SURGE EXPECTED TO PASS ACROSS THE AREA
AIRPORTS WITH WINDS BECOMING NORTHERLY AROUND 18Z. A FEW PASSING
SNOW SHOWERS STILL EXPECTED ACROSS THE PLAINS THROUGH THE
AFTERNOON...MAINLY NORTH AND EAST OF THE DENVER AREA. A SMALL
CHANCE OF SHOWERS MOVING ACROSS THE AREA AIRPORTS WITH POSSIBLE
MVFR CONDITIONS. SNOW FALL THAT DOES OCCUR WILL BE LIGHT WITH LESS
THAN AN INCH OF SNOW ACCUMULATION. MOUNTAIN WAVE APPEARS LESS
LIKELY FOR THE FRONT RANGE TONIGHT...BUT WILL KEEP THE POTENTIAL
FOR SOME GUSTS TO 40 KTS AT BJC.
PREV DISCUSSION... /ISSUED 418 AM MST FRI FEB 15 2013/
SHORT TERM...A SERIES OF RIPPLES IN NORTHWEST FLOW ALOFT WILL
CONTINUE TODAY. VERY LIGHT SNOW SHOWERS CONTINUE ON THE
PLAINS...WITH NORTHWEST WINDS ALOFT SHIELDING AREAS CLOSE TO THE
FOOTHILLS. SURFACE OBSERVATIONS HAVE SHOWN DECENT SHOWER COVERAGE
BACK THROUGH THE LAST WAVE IN WYOMING DESPITE ONLY VERY WEAK RADAR
ECHOES. MOISTURE...LIFT...AND INSTABILITY ALL MORE LIMITED TODAY
ALTHOUGH THERE WILL BE SOME COOLING AGAIN WITH A FRONTAL SURGE
AROUND MIDDAY. THIS COULD ALLOW SHOWERS TO BE A BIT STRONGER AND
COULD ALLOW FOR THE SHOWERS TO BACK INTO DENVER OR BRIEFLY
OVERPOWER THE DOWNSLOPING...BUT STILL EXPECT ANYTHING TO BE QUITE
LIGHT. MADE ONLY A SLIGHT UPWARD NUDGE TO POPS AS MUCH OF THE SNOW
WILL BE TRACE AMOUNTS.
STRONG WARMING ALOFT SHOULD BRING A QUICK END TO THE SHOWERS IN
THE LATE AFTERNOON OR EARLY EVENING. SOME CLOUD COVER STILL
EXPECTED...ENHANCED BY A PERIOD OF MOUNTAIN WAVE ACTIVITY AS THE
WARMING ALOFT KICKS IN THIS EVENING. COULD EVEN BE A BRIEF HIGH
WIND THREAT...BUT CONDITIONS WILL ONLY BE FAVORABLE FOR A FEW
HOURS AND LOW LEVEL STABILITY WOULD LIKELY KEEP THE STRONGEST
WINDS FROM REACHING THE PLAINS. BEST GUESS IS A BRIEF MARGINAL
EVENT FOR THE BOULDER/NORTHERN JEFFCO FOOTHILLS AND NOT A LOT
ELSEWHERE...THEN THE AMPLIFICATION SHOULD DIMINISH OVERNIGHT BUT
MORE WIDESPREAD WINDY CONDITIONS AT LEAST ABOVE 7500 FEET.
DEVELOPING WINDS AND SOME CLOUD COVER WILL LIKELY BRING SOME
WARMING LATER TONIGHT IN MANY AREAS...AND MILDER TEMPERATURES
EVERYWHERE WITH THE POSSIBLE EXCEPTION OF JACKSON/GRAND COUNTY
VALLEYS WHICH WILL LIKELY BE BELOW ZERO UNDER MOSTLY CLEAR SKIES.
LONG TERM...FAIRLY WEAK NORTHWESTERLY FLOW ALOFT IS PROGGED ON
SATURDAY WITH AN UPPER RIDGE TO MOVE ACROSS COLORADO THROUGH THE DAY
INTO SATURDAY NIGHT. THE FLOW ALOFT BECOME WESTERLY LATE SATURDAY
NIGHT...THEN WEST-SOUTHWESTERLY ON SUNDAY. THE NEXT UPPER TROUGH
IS PROGGED TO MOVE ACROSS COLORADO SUNDAY NIGHT INTO MONDAY
MORNING. THE SYNOPTIC SCALE ENERGY FOR THE CWA IS BENIGN SATURDAY
AND SATURDAY NIGHT. ON SUNDAY AND SUNDAY EVENING...UPWARD ENERGY
IS EXPECTED. DOWNWARD MOTION IS PROGGED FOR THE FORECAST AREA BY
12Z MONDAY MORNING. THE BOUNDARY LAYER WINDS ARE PROGGED TO BE
DOWNSLOPING IN NATURE SATURDAY INTO SATURDAY NIGHT. SUNDAY`S
SHOULD BE NORMAL PATTERNS EARLY...THEN A COLD FRONT WITH UPSLOPE IS
PROGGED IN DURING THE AFTERNOON. THE NORTHERLY FLOW BECOMES MORE
NORTHWESTERLY BY LATER SUNDAY NIGHT. FOR MOISTURE...SATURDAY AND
SATURDAY NIGHT ARE DRY...THEN MOISTURE INCREASES AND DEEPENS
SOMEWHAT THROUGH THE DAY SUNDAY. MOISTURE LOOKS FAIRLY DEEP
SUNDAY NIGHT AND THE NAM ACTUALLY HAS MORE THAN THE GFS. THE
ECMWF HAS THE LEAST MOISTURE. THE QPF FIELDS HAVE NO MEASURABLE
PRECIPITATION SATURDAY THROUGH SUNDAY. THEN BY SUNDAY NIGHT...
THERE IS A TAD OF MEASURABLE SNOWFALL OVER THE MOUNTAINS...
FOOTHILLS AND IMMEDIATE PLAINS. WILL GO WITH "CHANCE"S OVER THE
FOOTHILLS AND MOUNTAINS SUNDAY NIGHT...AND "SLIGHT CHANCE"S OVER
THE WESTERN PLAINS AND PALMER RIDGE. NOT TOO EXCITING. FOR
TEMPERATURES...SATURDAY`S HIGHS STILL LOOK TO BE 7-11 C WARMER THAN
TODAY`S. SUNDAY`S ARE CLOSE TO SATURDAY`S. FOR THE LATER DAYS...
MONDAY THROUGH THURSDAY...MODELS GET THE WEAK UPPER TROUGH
THROUGH THE CWA EARLY MONDAY MORNING...WITH STRONG NORTHWESTERLY
FLOW ALOFT MONDAY. THE FLOW ALOFT DECREASES AND BECOMES ZONAL
LATER MONDAY INTO MID DAY TUESDAY AS AN UPPER RIDGE MOVES ACROSS
COLORADO. SOUTHWESTERLY FLOW ALOFT INCREASES OVER THE CWA TUESDAY
AND WEDNESDAY. BY LATE WEDNESDAY AND WEDNESDAY NIGHT...MODELS SHOW
A PRETTY DECENT UPPER TROUGH/CLOSED LOW TO GET INTO COLORADO. THE
ECMWF SOLUTION LOOKS MORE FAVORABLE FOR A DECENT SNOWFALL EAST OF
THE DIVIDE WITH THE CIRCULATION CENTER TO MOVE EASTWARD ACROSS
NORTHERN NEW MEXICO WEDNESDAY NIGHT INTO THURSDAY MORNING. THE GFS
ISN`T BAD...SHOWING THE CIRCULATION A TAD FURTHER NORTH...HOWEVER
IT ALSO HAS ANOTHER CIRCULATION WELL NORTH OF COLORADO INSIDE THE
LARGE UPPER TROUGH. IT`S STILL SO EARLY...ESPECIALLY CONSIDERING
THE MODEL PERFORMANCE THESE DAYS. MONDAY INTO EARLY WEDNESDAY LOOK
DRY WITH NEAR NORMALS TEMPERATURES. WILL GO WITH OR KEEP IN SNOW
CHANCES...OR SLIGHT CHANCES...WEDNESDAY AFTERNOON INTO THURSDAY
AFTERNOON.
AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT. LIGHT
SNOW SHOWERS WILL MAINLY BE EAST OF DENVER...BUT THERE IS A CHANCE
THAT THEY WILL BACK OVER THE CITY AND BRING MVFR CONDITIONS AND
LESS THAN AN INCH OF SNOW. THE HIGHEST THREAT FOR THIS IS IN THE
EARLY AFTERNOON. SHOWERS AND THE THREAT OF LOWER CEILINGS WILL BE
ENDING IN THE LATE AFTERNOON. MOUNTAIN WAVE LIKELY OVER THE FRONT
RANGE TONIGHT...STRONG WINDS MAINLY EXPECTED OVER THE FOOTHILLS
BUT POSSIBLE LLWS OR OCCASIONAL GUSTS TO 40 KNOTS AT KBJC.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1017 AM MST FRI FEB 15 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS LOOK ON TRACK. PASSING SHORTWAVE
ACROSS PLAINS IN NORTHWEST FLOW PRODUCING LIGHT SNOW SHOWERS NORTH
AND EAST OF DENVER AREA. ACROSS MOUNTAINS...GOOD OROGRAPHICS
KEEPING LIGHT SNOW GOING DESPITE STRONG SUBSIDENCE AND STABILITY.
LATEST RAP CROSS SECTIONS SHOWING ANOTHER WEAK MID LEVEL SHORTWAVE
CLIPPING THE NORTHEAST CORNER DURING THE AFTERNOON WITH SOME MID
LEVEL QG ASCENT. NEARBY JET WILL HELP PRODUCE SOME SNOW SHOWERS
ACROSS THE PLAINS INTO THE EARLY EVENING. NOT EXPECTING MUCH IN
THE WAY OF ACCUMULATION WITH THE SHOWERS...THOUGH THE LIFT AND
SLIGHT COOLING WITH A FRONTAL SURGE COULD PRODUCE SOME BRIEF
ACCUMULATION WITH THE STRONGER SHOWERS. STILL EXPECTING ANY
ACCUMULATION TO BE LESS THAN AN INCH...EVEN WITH THE STRONGER
ACTIVITY. MOUNTAIN ACTIVITY TO GRADUALLY DECREASE BY THE EVENING
AS MOISTURE DEPTH DECREASES. FOR TONIGHT...DESPITE THE WARMING
ALOFT AND POTENTIAL FOR BRIEF MOUNTAIN WAVE...THREAT FOR HIGH
WINDS APPEARS LOW WITH THE GUSTY WINDS CONFINED TO THE HIGHER
RIDGES.
.AVIATION...CURRENT TAF TRENDS ON TRACK WITH VFR CONDITIONS
PREVAILING. WEAK NORTHERLY SURGE EXPECTED TO PASS ACROSS THE AREA
AIRPORTS WITH WINDS BECOMING NORTHERLY AROUND 18Z. A FEW PASSING
SNOW SHOWERS STILL EXPECTED ACROSS THE PLAINS THROUGH THE
AFTERNOON...MAINLY NORTH AND EAST OF THE DENVER AREA. A SMALL
CHANCE OF SHOWERS MOVING ACROSS THE AREA AIRPORTS WITH POSSIBLE
MVFR CONDITIONS. SNOW FALL THAT DOES OCCUR WILL BE LIGHT WITH LESS
THAN AN INCH OF SNOW ACCUMULATION. MOUNTAIN WAVE APPEARS LESS
LIKELY FOR THE FRONT RANGE TONIGHT...BUT WILL KEEP THE POTENTIAL
FOR SOME GUSTS TO 40 KTS AT BJC.
&&
.PREV DISCUSSION... /ISSUED 418 AM MST FRI FEB 15 2013/
SHORT TERM...A SERIES OF RIPPLES IN NORTHWEST FLOW ALOFT WILL
CONTINUE TODAY. VERY LIGHT SNOW SHOWERS CONTINUE ON THE
PLAINS...WITH NORTHWEST WINDS ALOFT SHIELDING AREAS CLOSE TO THE
FOOTHILLS. SURFACE OBSERVATIONS HAVE SHOWN DECENT SHOWER COVERAGE
BACK THROUGH THE LAST WAVE IN WYOMING DESPITE ONLY VERY WEAK RADAR
ECHOES. MOISTURE...LIFT...AND INSTABILITY ALL MORE LIMITED TODAY
ALTHOUGH THERE WILL BE SOME COOLING AGAIN WITH A FRONTAL SURGE
AROUND MIDDAY. THIS COULD ALLOW SHOWERS TO BE A BIT STRONGER AND
COULD ALLOW FOR THE SHOWERS TO BACK INTO DENVER OR BRIEFLY
OVERPOWER THE DOWNSLOPING...BUT STILL EXPECT ANYTHING TO BE QUITE
LIGHT. MADE ONLY A SLIGHT UPWARD NUDGE TO POPS AS MUCH OF THE SNOW
WILL BE TRACE AMOUNTS.
STRONG WARMING ALOFT SHOULD BRING A QUICK END TO THE SHOWERS IN
THE LATE AFTERNOON OR EARLY EVENING. SOME CLOUD COVER STILL
EXPECTED...ENHANCED BY A PERIOD OF MOUNTAIN WAVE ACTIVITY AS THE
WARMING ALOFT KICKS IN THIS EVENING. COULD EVEN BE A BRIEF HIGH
WIND THREAT...BUT CONDITIONS WILL ONLY BE FAVORABLE FOR A FEW
HOURS AND LOW LEVEL STABILITY WOULD LIKELY KEEP THE STRONGEST
WINDS FROM REACHING THE PLAINS. BEST GUESS IS A BRIEF MARGINAL
EVENT FOR THE BOULDER/NORTHERN JEFFCO FOOTHILLS AND NOT A LOT
ELSEWHERE...THEN THE AMPLIFICATION SHOULD DIMINISH OVERNIGHT BUT
MORE WIDESPREAD WINDY CONDITIONS AT LEAST ABOVE 7500 FEET.
DEVELOPING WINDS AND SOME CLOUD COVER WILL LIKELY BRING SOME
WARMING LATER TONIGHT IN MANY AREAS...AND MILDER TEMPERATURES
EVERYWHERE WITH THE POSSIBLE EXCEPTION OF JACKSON/GRAND COUNTY
VALLEYS WHICH WILL LIKELY BE BELOW ZERO UNDER MOSTLY CLEAR SKIES.
LONG TERM...FAIRLY WEAK NORTHWESTERLY FLOW ALOFT IS PROGGED ON
SATURDAY WITH AN UPPER RIDGE TO MOVE ACROSS COLORADO THROUGH THE DAY
INTO SATURDAY NIGHT. THE FLOW ALOFT BECOME WESTERLY LATE SATURDAY
NIGHT...THEN WEST-SOUTHWESTERLY ON SUNDAY. THE NEXT UPPER TROUGH
IS PROGGED TO MOVE ACROSS COLORADO SUNDAY NIGHT INTO MONDAY
MORNING. THE SYNOPTIC SCALE ENERGY FOR THE CWA IS BENIGN SATURDAY
AND SATURDAY NIGHT. ON SUNDAY AND SUNDAY EVENING...UPWARD ENERGY
IS EXPECTED. DOWNWARD MOTION IS PROGGED FOR THE FORECAST AREA BY
12Z MONDAY MORNING. THE BOUNDARY LAYER WINDS ARE PROGGED TO BE
DOWNSLOPING IN NATURE SATURDAY INTO SATURDAY NIGHT. SUNDAY`S
SHOULD BE NORMAL PATTERNS EARLY...THEN A COLD FRONT WITH UPSLOPE IS
PROGGED IN DURING THE AFTERNOON. THE NORTHERLY FLOW BECOMES MORE
NORTHWESTERLY BY LATER SUNDAY NIGHT. FOR MOISTURE...SATURDAY AND
SATURDAY NIGHT ARE DRY...THEN MOISTURE INCREASES AND DEEPENS
SOMEWHAT THROUGH THE DAY SUNDAY. MOISTURE LOOKS FAIRLY DEEP
SUNDAY NIGHT AND THE NAM ACTUALLY HAS MORE THAN THE GFS. THE
ECMWF HAS THE LEAST MOISTURE. THE QPF FIELDS HAVE NO MEASURABLE
PRECIPITATION SATURDAY THROUGH SUNDAY. THEN BY SUNDAY NIGHT...
THERE IS A TAD OF MEASURABLE SNOWFALL OVER THE MOUNTAINS...
FOOTHILLS AND IMMEDIATE PLAINS. WILL GO WITH "CHANCE"S OVER THE
FOOTHILLS AND MOUNTAINS SUNDAY NIGHT...AND "SLIGHT CHANCE"S OVER
THE WESTERN PLAINS AND PALMER RIDGE. NOT TOO EXCITING. FOR
TEMPERATURES...SATURDAY`S HIGHS STILL LOOK TO BE 7-11 C WARMER THAN
TODAY`S. SUNDAY`S ARE CLOSE TO SATURDAY`S. FOR THE LATER DAYS...
MONDAY THROUGH THURSDAY...MODELS GET THE WEAK UPPER TROUGH
THROUGH THE CWA EARLY MONDAY MORNING...WITH STRONG NORTHWESTERLY
FLOW ALOFT MONDAY. THE FLOW ALOFT DECREASES AND BECOMES ZONAL
LATER MONDAY INTO MID DAY TUESDAY AS AN UPPER RIDGE MOVES ACROSS
COLORADO. SOUTHWESTERLY FLOW ALOFT INCREASES OVER THE CWA TUESDAY
AND WEDNESDAY. BY LATE WEDNESDAY AND WEDNESDAY NIGHT...MODELS SHOW
A PRETTY DECENT UPPER TROUGH/CLOSED LOW TO GET INTO COLORADO. THE
ECMWF SOLUTION LOOKS MORE FAVORABLE FOR A DECENT SNOWFALL EAST OF
THE DIVIDE WITH THE CIRCULATION CENTER TO MOVE EASTWARD ACROSS
NORTHERN NEW MEXICO WEDNESDAY NIGHT INTO THURSDAY MORNING. THE GFS
ISN`T BAD...SHOWING THE CIRCULATION A TAD FURTHER NORTH...HOWEVER
IT ALSO HAS ANOTHER CIRCULATION WELL NORTH OF COLORADO INSIDE THE
LARGE UPPER TROUGH. IT`S STILL SO EARLY...ESPECIALLY CONSIDERING
THE MODEL PERFORMANCE THESE DAYS. MONDAY INTO EARLY WEDNESDAY LOOK
DRY WITH NEAR NORMALS TEMPERATURES. WILL GO WITH OR KEEP IN SNOW
CHANCES...OR SLIGHT CHANCES...WEDNESDAY AFTERNOON INTO THURSDAY
AFTERNOON.
AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT. LIGHT
SNOW SHOWERS WILL MAINLY BE EAST OF DENVER...BUT THERE IS A CHANCE
THAT THEY WILL BACK OVER THE CITY AND BRING MVFR CONDITIONS AND
LESS THAN AN INCH OF SNOW. THE HIGHEST THREAT FOR THIS IS IN THE
EARLY AFTERNOON. SHOWERS AND THE THREAT OF LOWER CEILINGS WILL BE
ENDING IN THE LATE AFTERNOON. MOUNTAIN WAVE LIKELY OVER THE FRONT
RANGE TONIGHT...STRONG WINDS MAINLY EXPECTED OVER THE FOOTHILLS
BUT POSSIBLE LLWS OR OCCASIONAL GUSTS TO 40 KNOTS AT KBJC.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS NEW YORK NY
346 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT MOVES ACROSS THE REGION TONIGHT AND STALLS TO OUR EAST
ON SATURDAY. A NOR`EASTER WILL DEVELOP SATURDAY NIGHT WELL
SOUTHEAST OF MONTAUK AND TRACK TOWARDS THE CANADIAN MARITIMES WITH
THE HEAVIEST PRECIPITATION REMAINING JUST EAST OF THE AREA. COLD
CANADIAN HIGH PRESSURE GRADUALLY BUILDS IN FOR SUNDAY INTO
MONDAY. A COLD FRONT TRACKS ACROSS THE REGION LATE TUESDAY
FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH THURSDAY. A COMPLEX
FRONTAL SYSTEM WILL APPROACH ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 3 PM...COLD FRONT IS ENTERING ORANGE COUNTY WITH WIND SHIFT
SEEN IN THE METARS. FRONT SLIDES EAST OF US TONIGHT WITH COLD
ADVECTION OVER THE REGION BEGINS. LIGHT PCPN OVER SOUTH CENTRAL PA
EXPANDS RAPIDLY THIS EVENING WITH ONSET AROUND 10 PM OVER NE NJ.
LATEST HRRR THOUGH SUGGEST LIGHT PCPN COULD EVEN MOVE IN A BIT
SOONER.
WE`RE IN AN AREA OF COUPLED JET STREAKS THAT IS PROVIDING ENOUGH
OMEGA FOR THE LIGHT PCPN. QPF IS LESS THAN A QUARTER INCH AND
PERHAPS LESS THAN A TENTH. TEMPS WILL FALL INTO THE 20`S OVER THE
INTERIOR WITH 30`S ALONG THE COAST. THUS...PCPN STARTS AS LIGHT
RAIN ALONG THE COAST AND THEN MIXES WITH WET SNOW...LITTLE OR NO
ACCUMULATION. INLAND...THE PCPN IS MAINLY LIGHT SNOW...THUS 1 TO
LOCALLY 2 INCHES ARE FCST WITH THE MAIN ACCUMULATION OCCURRING ON
THE SNOW PACK DUE TO MARGINAL TEMPS AT THE START OF THE PCPN.
LIGHT PCPN AXIS SLOWLY SHIFTS EAST BY EARLY SATURDAY.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
FOCUS OF ATTENTION IS ON EXPLOSIVE CYCLOGENESIS FORCED BY THE
160+ KT SUB TROPICAL JET LEFT FRONT QUAD ON SATURDAY NIGHT. BASED
ON EXTENSIVE ANALYSIS OF ENSEMBLE SYSTEMS AND COLLABORATION WITHIN
THE NATIONAL WEATHER SERVICE INCLUDING 6 COASTAL WFO`S AND HPC
WWD...CONFIDENCE IS INCREASING ON A NEAR MISS FOR SIGNIFICANT
PCPN SATURDAY NIGHT IN OUR FCST AREA.
HAVE SEEN 12Z ECMWF...15Z SREF...12Z GEFS AND 18Z NAM.
THUS...GOING WITH A CHANCE FOR VERY LIGHT PCPN WHICH WOULD
INCLUDE SPRINKLES AND FLURRIES DURING THE DAY ON SATURDAY WITH
HIGH TEMPS CLOSE TO THE SLIGHT COOLER NAM MOS.
AS THE NOR`EASTER SPINS UP WELL OFF THE MID ATLANTIC COAST
SATURDAY EVENING...POPS INCREASE TO CATEGORICAL EAST WITH LOW
CHANCE WEST. PCPN IS ALL SNOW. HAVE AMOUNTS OF 2-3" FAR EAST AND
AROUND AN INCH FROM NEW HAVEN TO WESTERN SUFFOLK. ELSEWHERE IT`S
JUST A DUSTING. EVEN THESE AMOUNTS COULD BE HIGH.
WILL KEEP THE OUTLOOK FOR THE FAR EASTERN ZONE WITH LOW CHANCE FOR
THE TRACK TO SHIFT BACK SLIGHTLY TO THE WEST.
WINDS REALLY START TO INCREASE AFTER MIDNIGHT.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
MEDIUM RANGE MODEL GUIDANCE IS STILL IN GENERAL AGREEMENT THROUGH
THE END OF THE WEEK. TO START...INTENSE LOW PRESSURE WILL BE MOVING
UP TROUGH THE CANADIAN MARITIMES ON SUNDAY AS ITS PARENT CLOSED
UPPER LOW TRAVERSES THE REGION ON SUNDAY...WITH COLD/BLUSTERY
CONDITIONS. NW FLOW 20-30 MPH WITH GUSTS 35-45 MPH AND TEMPS ONLY
RISING TO THE UPPER 20S AND LOWER 30S WILL RESULT IN WIND CHILLS IN
THE TEENS DURING THE DAY ON SUNDAY. WINDS WILL STILL REMAIN QUITE
BRISK IN TO SUNDAY NIGHT...SO AS TEMPS FALL INTO THE TEENS AND LOWER
20S SUNDAY NIGHT...WIND CHILLS OF OF ZERO TO 10 BELOW ARE LIKELY.
TEMPS AND WIND CHILLS SHOULD RECOVER A LITTLE MON INTO MON NIGHT AS
A NARROW HIGH PRESSURE RIDGE SLIDES ACROSS...WITH HIGHS MAINLY 30-35
AND LOWS MON NIGHT IN THE 20S. AN ACCOMPANYING UPPER RIDGE SHOULD
SLIDE BY TUE MORNING...ALLOWING A FRONTAL SYSTEM TO IMPACT THE AREA
FROM THE WEST TUE INTO TUE NIGHT. IF PCPN ARRIVES EARLY ENOUGH ON
TUE...IT COULD BEGIN AS A BRIEF PD OF SNOW OR A RAIN/SNOW MIX ACROSS
THE INTERIOR...OTHERWISE RAIN SHOULD BE THE PREDOMINANT P-TYPE
DURING THE DAY. AFTER COLD FROPA TUE EVENING...PCPN COULD CHANGE
BACK TO SNOW...ESPECIALLY OVER THE INTERIOR...AS COLDER AIR BEGINS
TO FILTER BACK IN.
THE FLOW ALOFT WILL BEGIN TO TRANSITION TO A MORE BLOCKY REGIME
DURING MID TO LATE NEXT WEEK...WITH TEMPS GENERALLY NEAR AVG.
FIRST...HIGH PRESSURE WILL SLIDE ACROSS WED INTO THU EVENING...THEN
AS ONE LEG OF A DEVELOPING OMEGA OR REX BLOCK BECOMES ESTABLISHED
OVER THE NRN PLAINS LATE IN THE WEEK...A SERIES OF SRN STREAM
DISTURBANCES TRAVELING ALONG ITS SRN PERIPHERY WILL IMPACT THE AREA.
THE FIRST OF THESE SHOULD BRING A LIGHT SNOWFALL EVENT FRI INTO FRI
NIGHT...AS HIGH PRESSURE TO THE NE SUPPLIES COLD SFC AIR AND
WESTERLY FLOW ALOFT PREVENTS MID LEVEL WARMING. THE ECMWF HAS BEEN
CONSISTENTLY PREDICTING A MORE SIGNIFICANT SRN STREAM LOW BEYOND THE
END OF THE FCST PERIOD THAT WILL NEED TO BE WATCHED...SO WINTER
APPEARS FAR FROM BEING OVER.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
A COLD FRONT APPROACHES THIS AFTERNOON AND STALLS BRIEFLY ACROSS
THE AREA AS A WAVE OF LOW PRESSURE PASSES TO THE SOUTH AND EAST
TONIGHT. THE FRONT THEN GRADUALLY WORKS EAST ON SAT.
S/SW WINDS LESS THAN 10 KT THIS AFT MAY BRIEFLY BECOME VARIABLE
OR A LIGHT W/NW THIS EVENING AS THE FRONT MOVES INTO THE AREA.
POTENTIAL FOR POST-FRONTAL PCPN TO DEVELOP LATE TONIGHT WITH MVFR
CONDITIONS. IFR POSSIBLE ACROSS THE LOWER HUDSON VALLEY WHERE PCPN
WILL LIKELY BE ALL SNOW. LIGHT RAIN AT THE ONSET WOULD TRANSITION
OVER TO A WET SNOW TOWARD DAYBREAK. POTENTIAL FOR AROUND AN INCH
AT KHPN AND KSWF...ELSEWHERE LITTLE OR NO SNOW ACCUMULATION
ON RUNWAYS WITH TEMPERATURES JUST ABOVE FREEZING.
GENERALLY VFR ON SAT WITH N WINDS AROUND 10 KT. OCCASIONAL MVFR
CIGS...ESPECIALLY EAST OF THE NYC TERMINALS.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: WINDS MAY BECOME LIGHT AND VARIABLE OR LIGHT
W/NW PRIOR TO 22Z.
KJFK FCSTER COMMENTS: WINDS MAY VARY BETWEEN 190-220 THIS AFTERNOON.
KLGA FCSTER COMMENTS: AN OCCASIONAL GUST INTO THE UPPER TEENS
POSSIBLE THIS AFTERNOON.
KTEB FCSTER COMMENTS: WINDS MAY BECOME LIGHT AND VARIABLE OR LIGHT
W/NW PRIOR TO 22Z.
KHPN FCSTER COMMENTS: WINDS MAY BECOME LIGHT AND VARIABLE OR LIGHT
W/NW PRIOR TO 22Z.
KISP FCSTER COMMENTS: WINDS MAY VARY BETWEEN 190-220 THIS AFTERNOON.
.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.SAT...MVFR POSSIBLE EAST OF NYC TERMINALS IN THE AFT.
.SAT NIGHT-SUN...OFFSHORE LOW DEVELOPMENT WILL NEED TO WATCHED FOR
ADDITIONAL PCPN. STRONG NW FLOW WITH GUSTS OF 35 TO 40 KT POSSIBLE
ON SUN.
.MON...VFR. GUSTY NW FLOW 25 TO 30 KT.
.TUE...PSBL MVFR OR LOWER WITH PCPN. GUSTY SW FLOW.
.WED...VFR. GUSTY W FLOW.
&&
.MARINE...
SUB-SCA CONDITIONS PREVAIL ON ALL WATERS INTO SATURDAY. WINDS VEER
NORTH BY LATE TONIGHT AND INCREASE ON SATURDAY.
GALES WILL LIKELY DEVELOP...ESPECIALLY EAST...LATE SAT
NIGHT AS LOW PRESSURE WELL SOUTHEAST OF MONTAUK RAPIDLY DEEPENS.
THUS GALE WATCH HAS BEEN ISSUED.
GALES LIKELY ON ALL WATERS ON SUNDAY IN THE WAKE OF INTENSE LOW
PRESSURE DEPARTING INTO THE CANADIAN MARITIMES...LASTING INTO SUNDAY
NIGHT-MON ON THE OCEAN AND THE EASTERN SOUND/BAYS.
QUIET CONDS SHOULD RETURN BY LATE DAY MON OR MON EVENING AS WEAK
HIGH PRESSURE SLIDES ACROSS. INCREASING SW FLOW AHEAD OF AN
APPROACHING FRONTAL SYSTEM COULD BRING MARGINAL SCA CONDS TO THE
OCEAN WATERS FROM LATE DAY TUE INTO TUE EVENING...CONTINUING IN W-NW
POST-FRONTAL FLOW ON WED.&&
.HYDROLOGY...
NO HYDROLOGIC IMPACT EXPECTED WITH LIGHT PCPN THOUGH SATURDAY
NIGHT.
QPF WITH FRONTAL SYSTEMS ON TUE /MOSTLY RAIN/ AND AGAIN ON FRI
/SNOW/ SHOULD BE LIGHT AND NOT PRESENT ANY PROBLEMS.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TONGUE
NEAR TERM...TONGUE
SHORT TERM...TONGUE
LONG TERM...GOODMAN
AVIATION...DW
MARINE...GOODMAN/TONGUE
HYDROLOGY...TONGUE
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
249 PM EST FRI FEB 15 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 335 AM EST FRI FEB 15 2013
A BROAD UPPER LEVEL LOW WILL SPREAD ACROSS THE GREAT LAKES REGION
THROUGH TOMORROW BRINGING PERIODIC CHANCES FOR LIGHT SNOW SHOWERS.
HIGH PRESSURE WILL THEN BUILD INTO CENTRAL INDIANA BY SUNDAY AS
THE AFOREMENTIONED LOW PUSHES OFF TO THE EAST. AFTER DRY CONDITIONS
ON SUNDAY...ANOTHER UPPER LEVEL LOW WILL BRING PRECIP TO THE
REGION ON MONDAY AND TUESDAY.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1240 PM EST FRI FEB 15 2013
1230 PM UPDATE...CONVECTIVE BANDS OF MODERATE TO HEAVY SNOW IMPACT
THE NORTHERN PORTIONS OF THE FORECAST AREA AT THIS TIME. HAVE BUMPED
UP TO A BRIEF PERIOD OF LIKELY POPS FROM KOKOMO AND TIPTON EAST
THROUGH MUNCIE AND WINCHESTER FOR THE NEXT COUPLE HOURS BASED ON
RADAR TRENDS. BRIEF PERIODS OF HEAVY SNOW DROPPING VISIBILITIES
BELOW 1/2SM IN THE STRONGER SNOW SHOWERS AND CONSIDERING THE
CONVECTIVE NATURE OF THE PRECIP...COULD SEE ICE PELLETS MIX IN
SPORADICALLY. ALSO LIKELY TO SEE QUICK ACCUMS OF A DUSTING TO HALF
INCH WITH THE HEAVIER SNOW SHOWERS...MELTING ONCE SNOW ENDS AS TEMPS
HOVER NEAR FREEZING.
PREVIOUS DISCUSSION FOLLOWS.
SCATTERED LIGHT SNOW AND FLURRIES EXPANDING ACROSS MUCH OF THE
NORTHERN PART OF THE FORECAST AREA SO FAR THIS MORNING AS THE
UPPER WAVE AND ITS ASSOCIATED FORCING MOVE THROUGH. TEMPS ACROSS
THE FORECAST AREA WERE IN THE LOWER AND MID 30S AT 14Z.
FORECAST IN GREAT SHAPE AND HAVE MADE ONLY MINOR ADJUSTMENTS TO
ACCOUNT FOR ONGOING OBS. SCATTERED LIGHT SNOW DEVELOPING A TOUCH
FASTER THAN PREVIOUSLY THOUGHT AS THE STRONGEST FORCING ALOFT
ALREADY INTO THE REGION. EXPECT SNOW SHOWERS TO CONTINUE THROUGH
MID AFTERNOON AS THE UPPER WAVE TRANSITIONS ACROSS THE REGION AND
WILL CONTINUE WITH CHANCE POPS. RAP SOUNDINGS SHOWING SOME WEAK
INSTABILITY DEVELOPING THROUGH EARLY AFTERNOON ALONG WITH
STEEPENING LAPSE RATES UP THROUGH ABOUT 800MB. THIS WILL
CONTRIBUTE TO THE DEVELOPMENT OF A FEW STRONGER CONVECTIVE SNOW
SHOWERS BUT WITH SURFACE TEMPS NEAR TO JUST ABOVE FREEZING AND
LIMITED MOISTURE AVAILABLE...ACCUMULATION POTENTIAL WILL BE
MITIGATED WITH MOST LOCATIONS ONLY SEEING A FEW TENTHS AT BEST.
THE BIGGER IMPACT TO TRAVEL LIKELY TO BE QUICK DROPS IN
VISIBILITIES WITHIN HEAVIER SNOW SHOWERS. MOST PRECIP WILL BE DONE
BY MID AFTERNOON AS THE UPPER WAVE MOVES INTO OHIO. FORECAST HIGHS
IN THE LOW/MID 30S STILL LOOK TO BE ON TRACK.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 335 AM EST FRI FEB 15 2013
DRY CONDITIONS WILL PREVAIL TONIGHT...BUT THE POTENTIAL FOR
PERIODIC SNOW SHOWERS WILL RETURN EARLY SATURDAY MORNING AND
LINGER THROUGH THE DAY AS ANOTHER WEAKER SHORTWAVE PASSES IN THE
UPPER FLOW. WEAK LAKE EFFECT ENHANCEMENT COULD CONTRIBUTE TO SOME
LIGHT SNOW SHOWERS OVER THE NORTHEAST/EASTERN PORTIONS OF CENTRAL
INDIANA THROUGH SATURDAY NIGHT.
HIGH PRESSURE WILL RE-ESTABLISH ITSELF OVER THE AREA ON SATURDAY
NIGHT...RESULTING IN DRY CONDITIONS FOR SUNDAY. MODELS SEEM TO
HAVE A GOOD HANDLE ON THE COOLER AIR ASSOCIATED WITH THE SECOND
WAVE ON SATURDAY...SO STUCK CLOSE TO GUIDANCE.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 248 PM EST FRI FEB 15 2013
MODELS ARE IN GOOD AGREEMENT EARLY BUT SOLUTIONS SPREAD BY LATER IN
THE WEEK. THE LONG TERM WILL BEGIN WITH RAIN MONDAY NIGHT AS A COLD
FRONT APPROACHES CENTRAL INDIANA AND MOVES THROUGH THE STATE DURING
THE OVERNIGHT HOURS. RAIN WILL CHANGE OVER TO A MIX BEHIND THE COLD
FRONTAL PASSAGE LATE MONDAY NIGHT. ON TUESDAY MORNING COULD SEE A
BRIEF SNOW SHOWER BEFORE THE SYSTEM MOVES OUT AND COULD HOLD ON TO
FLURRIES IN THE NORTHEAST THROUGH THE DAY. CANADIAN HIGH PRESSURE
WILL MOVE INTO THE AREA AFTER THAT BRINGING EVEN COLDER TEMPERATURES
AND DRY WEATHER WITH IT. BY THURSDAY THE NEXT SYSTEM WILL SWING OUT
OF THE PLAINS AND BRING SOME ISENTROPIC LIFT TO THE AREA. MODELS ARE
SHOWING SOME DECENT TIMING DIFFERENCES ON THIS SYSTEM AND WITH THE
COLD AIR ENTRENCHED CAN SEE POTENTIAL FOR A WINTRY MIX WHICH COULD
INCLUDE ICE EARLY IN THE DAY. WITH HIGH UNCERTAINTY THAT FAR OUT
THOUGH WILL LEAVE AS SNOW IN THE MORNING WITH RAIN SNOW MIX
THEREAFTER AS THE WARMER AIR ARRIVES. THURSDAY NIGHT COULD CONTINUE
WITH THE RAIN SNOW MIX IN THE SOUTH AND SNOW IN THE NORTH. ALLBLEND
GENERALLY ACCEPTED. TEMPERATURES SHOULD BE NEAR NORMAL AFTER MONDAY
NIGHT.
&&
.AVIATION /DISCUSSION FOR 151800Z TAF ISSUANCE/...
ISSUED AT 1158 AM EST FRI FEB 15 2013
MAINLY MVFR CONDITIONS AT THE SITES FOR THE FIRST FEW HOURS THIS
AFTERNOON WITH SNOW SHOWERS MOVING THROUGH KLAF AND KIND ON AN
UPPER WAVE. COULD SEE A STRAY FLAKE AT KBMG OR KHUF BUT FOR THE
MOST PART SNOW SHOULD STAY TO THE NORTH. MVFR CEILINGS CAN BE FOUND
TO THE SOUTH THOUGH. RH CROSS SECTIONS INDICATE THAT
CLEARING/SCATTERING OUT COULD OCCUR AROUND 20-21Z IN THE NORTHWEST
AND MOVE ACROSS THE AREA FROM THERE. THESE FIELDS ALSO SHOW CLOUD
COVER FILLING BACK IN AFTER 9Z FROM THE NORTH.
CLOUDS MOVING OUT OF THE NW BY AROUND 21Z AND BACK IN AROUND 9Z AND
OVERSPREADING TO THE SOUTH AND EAST. CLOUD COVER MAY SCATTER UP
SATURDAY AFTERNOON.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....CP
AVIATION...CP
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1240 PM EST FRI FEB 15 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 335 AM EST FRI FEB 15 2013
A BROAD UPPER LEVEL LOW WILL SPREAD ACROSS THE GREAT LAKES REGION
THROUGH TOMORROW BRINGING PERIODIC CHANCES FOR LIGHT SNOW SHOWERS.
HIGH PRESSURE WILL THEN BUILD INTO CENTRAL INDIANA BY SUNDAY AS
THE AFOREMENTIONED LOW PUSHES OFF TO THE EAST. AFTER DRY CONDITIONS
ON SUNDAY...ANOTHER UPPER LEVEL LOW WILL BRING PRECIP TO THE
REGION ON MONDAY AND TUESDAY.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1240 PM EST FRI FEB 15 2013
1230 PM UPDATE...CONVECTIVE BANDS OF MODERATE TO HEAVY SNOW IMPACT
THE NORTHERN PORTIONS OF THE FORECAST AREA AT THIS TIME. HAVE BUMPED
UP TO A BRIEF PERIOD OF LIKELY POPS FROM KOKOMO AND TIPTON EAST
THROUGH MUNCIE AND WINCHESTER FOR THE NEXT COUPLE HOURS BASED ON
RADAR TRENDS. BRIEF PERIODS OF HEAVY SNOW DROPPING VISIBILITIES
BELOW 1/2SM IN THE STRONGER SNOW SHOWERS AND CONSIDERING THE
CONVECTIVE NATURE OF THE PRECIP...COULD SEE ICE PELLETS MIX IN
SPORADICALLY. ALSO LIKELY TO SEE QUICK ACCUMS OF A DUSTING TO HALF
INCH WITH THE HEAVIER SNOW SHOWERS...MELTING ONCE SNOW ENDS AS TEMPS
HOVER NEAR FREEZING.
PREVIOUS DISCUSSION FOLLOWS.
SCATTERED LIGHT SNOW AND FLURRIES EXPANDING ACROSS MUCH OF THE
NORTHERN PART OF THE FORECAST AREA SO FAR THIS MORNING AS THE
UPPER WAVE AND ITS ASSOCIATED FORCING MOVE THROUGH. TEMPS ACROSS
THE FORECAST AREA WERE IN THE LOWER AND MID 30S AT 14Z.
FORECAST IN GREAT SHAPE AND HAVE MADE ONLY MINOR ADJUSTMENTS TO
ACCOUNT FOR ONGOING OBS. SCATTERED LIGHT SNOW DEVELOPING A TOUCH
FASTER THAN PREVIOUSLY THOUGHT AS THE STRONGEST FORCING ALOFT
ALREADY INTO THE REGION. EXPECT SNOW SHOWERS TO CONTINUE THROUGH
MID AFTERNOON AS THE UPPER WAVE TRANSITIONS ACROSS THE REGION AND
WILL CONTINUE WITH CHANCE POPS. RAP SOUNDINGS SHOWING SOME WEAK
INSTABILITY DEVELOPING THROUGH EARLY AFTERNOON ALONG WITH
STEEPENING LAPSE RATES UP THROUGH ABOUT 800MB. THIS WILL
CONTRIBUTE TO THE DEVELOPMENT OF A FEW STRONGER CONVECTIVE SNOW
SHOWERS BUT WITH SURFACE TEMPS NEAR TO JUST ABOVE FREEZING AND
LIMITED MOISTURE AVAILABLE...ACCUMULATION POTENTIAL WILL BE
MITIGATED WITH MOST LOCATIONS ONLY SEEING A FEW TENTHS AT BEST.
THE BIGGER IMPACT TO TRAVEL LIKELY TO BE QUICK DROPS IN
VISIBILITIES WITHIN HEAVIER SNOW SHOWERS. MOST PRECIP WILL BE DONE
BY MID AFTERNOON AS THE UPPER WAVE MOVES INTO OHIO. FORECAST HIGHS
IN THE LOW/MID 30S STILL LOOK TO BE ON TRACK.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 335 AM EST FRI FEB 15 2013
DRY CONDITIONS WILL PREVAIL TONIGHT...BUT THE POTENTIAL FOR
PERIODIC SNOW SHOWERS WILL RETURN EARLY SATURDAY MORNING AND
LINGER THROUGH THE DAY AS ANOTHER WEAKER SHORTWAVE PASSES IN THE
UPPER FLOW. WEAK LAKE EFFECT ENHANCEMENT COULD CONTRIBUTE TO SOME
LIGHT SNOW SHOWERS OVER THE NORTHEAST/EASTERN PORTIONS OF CENTRAL
INDIANA THROUGH SATURDAY NIGHT.
HIGH PRESSURE WILL RE-ESTABLISH ITSELF OVER THE AREA ON SATURDAY
NIGHT...RESULTING IN DRY CONDITIONS FOR SUNDAY. MODELS SEEM TO
HAVE A GOOD HANDLE ON THE COOLER AIR ASSOCIATED WITH THE SECOND
WAVE ON SATURDAY...SO STUCK CLOSE TO GUIDANCE.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 330 AM EST FRI FEB 15 2013
MAIN FOCUS TO THE EXTENDED WILL BE ON POPS AS TWO SEPARATE SYSTEMS
WILL BRING CHANCES TO CENTRAL INDIANA NEXT WEEK.
LONG RANGE MODELS...INCLUDING THE ENSEMBLES...ARE HAVING SOME
DIFFERENCES HANDING THESE SYSTEMS WITH THE 00Z GEFS AND GFS
GENERALLY QUICKER AND NORTHEAST WITH THE ASSOCIATED LOW PRESSURE
CENTERS AND QPF ACROSS THE FORECAST AREA. THE REGIONAL
INITIALIZATION FORECAST SEEMS TO TAKE A BLEND OF THE EXTENDED OUTPUT
WHICH LOOKS REASONABLE.
A MODEL BLEND WOULD BRING A WARM FRONT ASSOCIATED WITH AN OCCLUDED
SYSTEM ACROSS CENTRAL INDIANA ON MONDAY FOLLOWED BY A COLD FRONT
MONDAY NIGHT. MODELS BRING MOST OF THE QPF IN MONDAY AFTERNOON AND
NIGHT AND BUFKIT PARTIAL THICKNESS METHOD ALONG WITH SOUNDINGS
SUGGEST ALL RAIN UNTIL AFTER 06Z...WHEN THE RAIN SHOULD MIX WITH OR
TURN TO SNOW FROM NORTHWEST TO SOUTHEAST BEHIND THE COLD FRONT. LEFT
SMALL TUESDAY MORNING SNOW CHANCES IN...BUT THEN HIGH PRESSURE WILL
BUILD IN FROM CENTRAL CANADA LEADING TO DRY AND COLDER WEATHER
THROUGH WEDNESDAY NIGHT. FINALLY...THE 12Z GFS AND GEFS WERE FURTHER
NORTH AND STRONGER BRINGING A STRONG LOW PRESSURE SYSTEM TO CENTRAL
MISSOURI BY 00Z FRIDAY FEBRUARY 22. THE 00Z ECMWF HAD IT MORE
UNORGANIZED ACROSS OKLAHOMA AND ARKANSAS BY THEN. AS A RESULT...NICE
GULF RETURN FLOW HAPPENS A BIT QUICKER IN THE GFS AND GEFS SOLUTIONS
AS DOES QPF BY 18Z MONDAY. AGAIN...WITH MODEL UNCERTAINTY...WILL
ACCEPT THE REGIONAL INITIALIZATION WHICH BRINGS LIKELY POPS
SOUTHWEST HALF ON THURSDAY. BUKFIT PARTIAL THICKNESSES SUGGEST THE
PRECIPITATION WILL START OFF ALL SNOW AND THEN MIX WITH RAIN IN THE
AFTERNOON FROM SOUTHWEST TO NORTHEAST.
WILL NOT MAKE ANY CHANGES TO TEMPERATURES AS OF YET WITH WELL ABOVE
NORMAL HIGHS IN THE 40S AND 50S ON MONDAY FALLING TO NORMAL TO BELOW
NORMAL THE REST OF THE WEEK.
&&
.AVIATION /DISCUSSION FOR 151800Z TAF ISSUANCE/...
ISSUED AT 1158 AM EST FRI FEB 15 2013
MAINLY MVFR CONDITIONS AT THE SITES FOR THE FIRST FEW HOURS THIS
AFTERNOON WITH SNOW SHOWERS MOVING THROUGH KLAF AND KIND ON AN
UPPER WAVE. COULD SEE A STRAY FLAKE AT KBMG OR KHUF BUT FOR THE
MOST PART SNOW SHOULD STAY TO THE NORTH. MVFR CEILINGS CAN BE FOUND
TO THE SOUTH THOUGH. RH CROSS SECTIONS INDICATE THAT
CLEARING/SCATTERING OUT COULD OCCUR AROUND 20-21Z IN THE NORTHWEST
AND MOVE ACROSS THE AREA FROM THERE. THESE FIELDS ALSO SHOW CLOUD
COVER FILLING BACK IN AFTER 9Z FROM THE NORTH.
CLOUDS MOVING OUT OF THE NW BY AROUND 21Z AND BACK IN AROUND 9Z AND
OVERSPREADING TO THE SOUTH AND EAST. CLOUD COVER MAY SCATTER UP
SATURDAY AFTERNOON.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...CP
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1214 PM EST FRI FEB 15 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 335 AM EST FRI FEB 15 2013
A BROAD UPPER LEVEL LOW WILL SPREAD ACROSS THE GREAT LAKES REGION
THROUGH TOMORROW BRINGING PERIODIC CHANCES FOR LIGHT SNOW SHOWERS.
HIGH PRESSURE WILL THEN BUILD INTO CENTRAL INDIANA BY SUNDAY AS
THE AFOREMENTIONED LOW PUSHES OFF TO THE EAST. AFTER DRY CONDITIONS
ON SUNDAY...ANOTHER UPPER LEVEL LOW WILL BRING PRECIP TO THE
REGION ON MONDAY AND TUESDAY.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 940 AM EST FRI FEB 15 2013
SCATTERED LIGHT SNOW AND FLURRIES EXPANDING ACROSS MUCH OF THE
NORTHERN PART OF THE FORECAST AREA SO FAR THIS MORNING AS THE
UPPER WAVE AND ITS ASSOCIATED FORCING MOVE THROUGH. TEMPS ACROSS
THE FORECAST AREA WERE IN THE LOWER AND MID 30S AT 14Z.
FORECAST IN GREAT SHAPE AND HAVE MADE ONLY MINOR ADJUSTMENTS TO
ACCOUNT FOR ONGOING OBS. SCATTERED LIGHT SNOW DEVELOPING A TOUCH
FASTER THAN PREVIOUSLY THOUGHT AS THE STRONGEST FORCING ALOFT
ALREADY INTO THE REGION. EXPECT SNOW SHOWERS TO CONTINUE THROUGH
MID AFTERNOON AS THE UPPER WAVE TRANSITIONS ACROSS THE REGION AND
WILL CONTINUE WITH CHANCE POPS. RAP SOUNDINGS SHOWING SOME WEAK
INSTABILITY DEVELOPING THROUGH EARLY AFTERNOON ALONG WITH
STEEPENING LAPSE RATES UP THROUGH ABOUT 800MB. THIS WILL
CONTRIBUTE TO THE DEVELOPMENT OF A FEW STRONGER CONVECTIVE SNOW
SHOWERS BUT WITH SURFACE TEMPS NEAR TO JUST ABOVE FREEZING AND
LIMITED MOISTURE AVAILABLE...ACCUMULATION POTENTIAL WILL BE
MITIGATED WITH MOST LOCATIONS ONLY SEEING A FEW TENTHS AT BEST.
THE BIGGER IMPACT TO TRAVEL LIKELY TO BE QUICK DROPS IN
VISIBILITIES WITHIN HEAVIER SNOW SHOWERS. MOST PRECIP WILL BE DONE
BY MID AFTERNOON AS THE UPPER WAVE MOVES INTO OHIO. FORECAST HIGHS
IN THE LOW/MID 30S STILL LOOK TO BE ON TRACK.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 335 AM EST FRI FEB 15 2013
DRY CONDITIONS WILL PREVAIL TONIGHT...BUT THE POTENTIAL FOR
PERIODIC SNOW SHOWERS WILL RETURN EARLY SATURDAY MORNING AND
LINGER THROUGH THE DAY AS ANOTHER WEAKER SHORTWAVE PASSES IN THE
UPPER FLOW. WEAK LAKE EFFECT ENHANCEMENT COULD CONTRIBUTE TO SOME
LIGHT SNOW SHOWERS OVER THE NORTHEAST/EASTERN PORTIONS OF CENTRAL
INDIANA THROUGH SATURDAY NIGHT.
HIGH PRESSURE WILL RE-ESTABLISH ITSELF OVER THE AREA ON SATURDAY
NIGHT...RESULTING IN DRY CONDITIONS FOR SUNDAY. MODELS SEEM TO
HAVE A GOOD HANDLE ON THE COOLER AIR ASSOCIATED WITH THE SECOND
WAVE ON SATURDAY...SO STUCK CLOSE TO GUIDANCE.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 330 AM EST FRI FEB 15 2013
MAIN FOCUS TO THE EXTENDED WILL BE ON POPS AS TWO SEPARATE SYSTEMS
WILL BRING CHANCES TO CENTRAL INDIANA NEXT WEEK.
LONG RANGE MODELS...INCLUDING THE ENSEMBLES...ARE HAVING SOME
DIFFERENCES HANDING THESE SYSTEMS WITH THE 00Z GEFS AND GFS
GENERALLY QUICKER AND NORTHEAST WITH THE ASSOCIATED LOW PRESSURE
CENTERS AND QPF ACROSS THE FORECAST AREA. THE REGIONAL
INITIALIZATION FORECAST SEEMS TO TAKE A BLEND OF THE EXTENDED OUTPUT
WHICH LOOKS REASONABLE.
A MODEL BLEND WOULD BRING A WARM FRONT ASSOCIATED WITH AN OCCLUDED
SYSTEM ACROSS CENTRAL INDIANA ON MONDAY FOLLOWED BY A COLD FRONT
MONDAY NIGHT. MODELS BRING MOST OF THE QPF IN MONDAY AFTERNOON AND
NIGHT AND BUFKIT PARTIAL THICKNESS METHOD ALONG WITH SOUNDINGS
SUGGEST ALL RAIN UNTIL AFTER 06Z...WHEN THE RAIN SHOULD MIX WITH OR
TURN TO SNOW FROM NORTHWEST TO SOUTHEAST BEHIND THE COLD FRONT. LEFT
SMALL TUESDAY MORNING SNOW CHANCES IN...BUT THEN HIGH PRESSURE WILL
BUILD IN FROM CENTRAL CANADA LEADING TO DRY AND COLDER WEATHER
THROUGH WEDNESDAY NIGHT. FINALLY...THE 12Z GFS AND GEFS WERE FURTHER
NORTH AND STRONGER BRINGING A STRONG LOW PRESSURE SYSTEM TO CENTRAL
MISSOURI BY 00Z FRIDAY FEBRUARY 22. THE 00Z ECMWF HAD IT MORE
UNORGANIZED ACROSS OKLAHOMA AND ARKANSAS BY THEN. AS A RESULT...NICE
GULF RETURN FLOW HAPPENS A BIT QUICKER IN THE GFS AND GEFS SOLUTIONS
AS DOES QPF BY 18Z MONDAY. AGAIN...WITH MODEL UNCERTAINTY...WILL
ACCEPT THE REGIONAL INITIALIZATION WHICH BRINGS LIKELY POPS
SOUTHWEST HALF ON THURSDAY. BUKFIT PARTIAL THICKNESSES SUGGEST THE
PRECIPITATION WILL START OFF ALL SNOW AND THEN MIX WITH RAIN IN THE
AFTERNOON FROM SOUTHWEST TO NORTHEAST.
WILL NOT MAKE ANY CHANGES TO TEMPERATURES AS OF YET WITH WELL ABOVE
NORMAL HIGHS IN THE 40S AND 50S ON MONDAY FALLING TO NORMAL TO BELOW
NORMAL THE REST OF THE WEEK.
&&
.AVIATION /DISCUSSION FOR 151800Z TAF ISSUANCE/...
ISSUED AT 1158 AM EST FRI FEB 15 2013
MAINLY MVFR CONDITIONS AT THE SITES FOR THE FIRST FEW HOURS THIS
AFTERNOON WITH SNOW SHOWERS MOVING THROUGH KLAF AND KIND ON AN
UPPER WAVE. COULD SEE A STRAY FLAKE AT KBMG OR KHUF BUT FOR THE
MOST PART SNOW SHOULD STAY TO THE NORTH. MVFR CEILINGS CAN BE FOUND
TO THE SOUTH THOUGH. RH CROSS SECTIONS INDICATE THAT
CLEARING/SCATTERING OUT COULD OCCUR AROUND 20-21Z IN THE NORTHWEST
AND MOVE ACROSS THE AREA FROM THERE. THESE FIELDS ALSO SHOW CLOUD
COVER FILLING BACK IN AFTER 9Z FROM THE NORTH.
CLOUDS MOVING OUT OF THE NW BY AROUND 21Z AND BACK IN AROUND 9Z AND
OVERSPREADING TO THE SOUTH AND EAST. CLOUD COVER MAY SCATTER UP
SATURDAY AFTERNOON.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...CP
AREA FORECAST DISCUSSION
NWS TOPEKA KS
311 PM CST FRI FEB 15 2013
.DISCUSSION...
12Z UPPER AIR DATA DEPICTED AT 130KT JET DIVING SOUTH OUT OF WESTERN
SASKATCHEWAN WITH WIDESPREAD 500MB TEMPS OF AROUND -40C OVER THE
NORTHERN PLAINS AND EASTERN CANADA. AN UPPER LEVEL TROF WAS MAKING
SOUTHWARD PROGRESS OUT OF THE WESTERN DAKOTAS IN RECENT HOURS PER
WATER VAPOR IMAGERY. WEAK RADAR RETURNS HAVE DEVELOPED OVER MUCH OF
NORTHERN KANSAS THOUGH DEWPOINT DEPRESSIONS AROUND 20F ARE LIKELY
KEEP MUCH OF THIS WEAK ACTIVITY FROM REACHING THE GROUND. 20Z
SURFACE-3KM LAPSE RATES NEAR 9C/KM WERE NOTED IN CENTRAL
NEBRASKA...WITH AROUND 8C/KM VALUES EAST AND ALSO SOUTHEAST INTO THE
LOCAL AREA.
THE MAIN ISSUES TONIGHT ARE WHERE AND HOW LONG THE SNOW SHOWERS WILL
LAST. THE VARIOUS GUIDANCE ALL POINTS TO A MORE SUSTAINED AREA OF
PRECIPITATION SOMEWHERE IN NORTHEAST KANSAS...WITH THE DETAILS THE
MAIN ISSUE. AS THE UPPER TROF CONTINUES SOUTH TO SOUTHEAST...THE
LAPSE RATES REMAIN NEAR 8C/KM WELL INTO THE NIGHT AS FRONTOGENESIS
AROUND 750MB INCREASES AND FOCUSES ON THE NORTHEAST TIP OF A
DEVELOPING THETA-E RIDGE AT THIS LEVEL...RESULTING IN GOOD LIFT
THROUGH THE DENDRITIC GROWTH ZONE. THE MOST RECENT HRRR AND RAP DATA
HAS BEEN PUSHING THIS AREA NORTHEAST...FAVORING FAR NORTHEAST KANSAS
MAINLY AROUND 03Z. HAVE INCREASED CHANCES AND AMOUNTS UP HERE...BUT
STILL LIMITED MOISTURE AND THE COVERAGE OF ANY BANDS AND EXACTLY
WHERE THIS WILL END UP KEEPS CHANCES BELOW LIKELY LEVELS. SOME BRIEF
MODERATE SNOWFALLS CAN BE EXPECTED IN THE HEAVIEST PRECIPITATION...
AND LOCAL AMOUNTS NEAR AN INCH SEEM PLAUSIBLE. ANY ACCUMULATING SNOW
SHOULD END WELL BEFORE SUNRISE AS THE UPPER TROF SWINGS INTO THE
MISSISSIPPI VALLEY. WESTERN AREAS SEE A QUICKLY DRYING TROPOSPHERE
THIS EVENING...BUT HIGH CLOUD RETURNS THERE LATE TONIGHT AS WARM AIR
ADVECTION ENSUES FROM THE UPPER PATTERN SHIFTING EAST. THOUGH
INSOLATION WILL BE LIMITED AS THE CLOUDS DEEPEN SATURDAY...SOUTHWEST
WINDS SHOULD SUPPORT TEMPS SEVERAL DEGREES ABOVE TODAYS LEVELS FOR
CENTRAL AND WESTERN LOCATIONS.
65
SHORTWAVE RIDGING AND WARM AIR ADVECTION IS EXPECTED TO BRING WARMER
TEMPS AND SUNNY SKIES TO THE AREA FOR SUNDAY. THEN THE NEXT
SHORTWAVE IS EXPECTED TO MOVE ACROSS THE CENTRAL AND NORTHERN PLAINS
BRINGING A COLD FRONT THROUGH THE AREA LATE SUNDAY NIGHT AND MONDAY
MORNING. MODELS CONTINUE TO SHOW THE BETTER MOISTURE TO THE EAST OF
THE FORECAST AREA. AND WITH THE FRONT PUSHING INTO MO BY THE LATE
MORNING HOURS...PRECIP CHANCES SHOULD BE CONFINED TO FAR EASTERN KS
DURING THE DAY MONDAY.
TUESDAY AND WEDNESDAY LOOK TO BE IN BETWEEN SYSTEMS WITH SURFACE
RIDGING BUILDING SOUTH THROUGH THE PLAINS. THIS SHOULD KEEP TEMPS
FROM WARMING UP VERY MUCH. THE NEXT BIG WEATHER MAKER LOOKS TO
IMPACT THE REGION WEDNESDAY NIGHT AND THURSDAY. BOTH THE GFS AND
ECMWF HAVE TRENDED SLIGHTLY SLOWER WITH THE UPPER CLOSED LOW AS IT
MOVES OUT OF THE SOUTHERN ROCKIES. HOWEVER THE GFS REMAINS SLIGHTLY
FASTER THAN THE GFS. THE OTHER TREND OF NOTE IS THE ECMWF FURTHER
NORTH WITH THE TRACK OF THE LOW PRESSURE SYSTEM. THIS COMPLICATES
THE FORECAST OF PRECIP TYPE QUITE A BIT. INITIALLY WITH THE COLD
SURFACE RIDGE IN PLACE WEDNESDAY...GFS FORECAST SOUNDINGS SUPPORT
ALL SNOW WEDNESDAY EVENING. HOWEVER BOTH MODELS SHOW STRONG WARM AIR
ADVECTION ALOFT AND A WARM NOSE DEVELOPING THROUGH THE NIGHT WITH
SURFACE TEMPS REMAINING IN THE 20S AND LOWER 30S. AS THE WARM AIR
ADVECTION DEVELOPS...FREEZING RAIN AND SLEET BECOME POSSIBLE WHILE
SURFACE TEMPS ARE BELOW FREEZING. ON TOP OF THIS IS THE POTENTIAL
FOR MID LEVEL DRY AIR TO WRAP UP IN THE SYSTEM AND FOR THE SOUNDINGS
TO LOOSE SATURATION WITHIN THE DENDRITIC GROWTH LAYER ADDING TO THE
POTENTIAL FOR FREEZING RAIN. REALLY THE TRACK OF THE SYSTEM DOES NOT
FAVOR AN ALL SNOW EVENT FOR THE BULK OF THE FORECAST AREA.
CONFIDENCE IN TRYING TO NAIL DOWN PRECIP TYPE IS VERY LOW AT THIS
POINT GIVEN THAT IT IS 6 DAYS OUT...BUT THINK THAT THE PROBABILITY
OF MIX WINTRY PRECIP IS HIGH ENOUGH THAT IT SHOULD BE MENTIONED IN
THE FORECAST. ONE SHOULD NOT GET CAUGHT UP ON WHERE THE FORECAST HAS
THE RAIN/SNOW LINE /WHICH IS LIKELY TO FLUCTUATE IN THE COMING
DAYS/...BUT THAT THERE IS THE POTENTIAL FOR A MIXED BAG OF PRECIP.
THINGS THAT COULD CHANGE THIS IS IF THE MAGNITUDE OF LOW LEVEL WARM
AIR ADVECTION WERE TO INCREASE AND RAISE SURFACE TEMPS ABOVE
FREEZING OR IF THE STORM SYSTEM TRENDS SOUTH AGAIN. IN ANY CASE IT
LOOKS TO BE MESSY.
WOLTERS
&&
.AVIATION...
CONFIDENCE IS NOT HIGH...BUT THERE CONTINUES TO BE INDICATIONS OF
SMALL AREAS OF SNOW DEVELOPING AFTER 23Z...WITH THE HEART AROUND
04Z AND IN THE KTOP AND KFOE VICINITY. THE MAIN ISSUES ARE JUST WHERE
THE SMALL AREAS WILL FORM AND HOW LOW CONDITIONS WILL GET. ENOUGH
CONFIDENCE EXISTS FOR A TEMPORARY IFR FORECAST FOR KTOP AND KFOE
WHEN THE SNOW SHOULD BE THE HEAVIEST.
65
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
403 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION THIS EVENING AND BRING SNOW SHOWERS
TO THE AREA. IN THE WAKE OF THE FRONT...COLDER TEMPERATURES WITH
SNOW SHOWERS ARE EXPECTED THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A BROAD 500MB TROUGH
ACROSS THE MIDWEST WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY
FLOW AHEAD OF THIS FEATURE. 700MB OMEGA INDICATES AN AREA OF LIFT
PUSHING EAST OF THE ALLEGHENY FRONT. THIS LIFT HAS BEEN
RESPONSIBLE FOR GENERALLY 1-2 INCHES OF SNOW ACCUMULATION IN THE
HIGHER ELEVATIONS OF THE ALLEGHENY FRONT. AT THE SURFACE...A COLD
FRONT HAS PUSHED NOW PUSHED EAST OF ZANESVILLE AND IS MOVING
ACROSS EASTERN OHIO. WITH THE FRONT...NUMEROUS SNOW SHOWERS ARE MOVING
ACROSS THE OHIO VALLEY.
THIS EVENING...THE COLD FRONT IS PROGGED TO BE REACH THE PITTSBURGH
METRO BY AROUND 23Z. THE FRONT WILL BRING SNOW SHOWERS...MODERATE
TO HEAVY AT TIMES IN LOCALIZED AREAS. WITH WARMER GROUND AHEAD OF THE
FRONT AND SHOT OF CAA LAGGING SOMEWHAT BEHIND THE FRONT...BELIEVE
THIS WILL LIMIT ACCUMULATION. THUS...WITH THE FRONTAL PASSAGE
ITSELF...SNOW ACCUMULATION WILL MOSTLY BE AN INCH OR LESS ACROSS
THE AREA...NOT OUT OF THE QUESTION A LOCATION COULD GET 2 INCHES
IN MORE LOCALIZED SNOW SHOWERS. HOWEVER...ACCUMULATION WILL MOSTLY
JUST BE ON GRASSY SURFACES AS THE BIGGER IMPACT WITH THE FRONTAL
PASSAGE WILL BE REDUCED VISIBILITIES TO LESS THAN A HALF MILE IN
THE STRONGER SNOW SHOWERS.
TONIGHT...THE FRONT WILL SLIDE EAST OF THE AREA AND CAA WILL
ENSUE. BEHIND THE FRONT...A WESTERLY COMPONENT WILL ALLOW FOR SOME
UPSLOPING ACROSS THE LAUREL HIGHLANDS AND ALLEGHENY FRONT
OVERNIGHT. HOWEVER...DEEP MOISTURE WILL NOT BE PRESENT IN THE WAKE
OF THE FRONT AND THUS ANTICIPATE THAT SNOW WILL BE GENERALLY LIGHT
WITH ADDITIONAL OVERNIGHT ACCUMULATION OF 1 TO 3 INCHES FOR
LOCATIONS ABOVE 2000 FT. ACROSS THE LOWLANDS...AN INVERSION AROUND
4-5KFT WILL LIMIT SNOW SHOWERS AND THUS ANTICIPATE LITTLE OR NO
ACCUMULATION OVERNIGHT. WITH A POST-FRONTAL ARCTIC AIR MASS
SETTLING INTO THE REGION...TEMPS TONIGHT WILL BE NOTICEABLY
COLDER. A MAV/MET BLEND WAS USED WITH LOWS RANGING FROM THE MID
TEENS NORTH AND EAST OF PITTSBURGH TO NEAR 20 IN PORTIONS OF
EASTERN OHIO AND NORTHERN WV.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
A MODEL CONSENSUS INDICATES THAT A MID-LEVEL TROUGH WILL CROSS THE
UPPER OHIO VALLEY SATURDAY INTO SATURDAY NIGHT...PROVIDING FORCING
FOR SCATTERED SNOW SHOWERS BEGINNING IN THE LATE MORNING INTO THE
AFTERNOON ON SATURDAY. WITH THE PASSAGE OF THE TROUGH AROUND AN
INCH OF SNOW IS EXPECTED GENERALLY ACROSS THE AREA...ALTHOUGH
LOCALIZED HIGHER AMOUNTS UP TO THREE INCHES CANNOT BE RULED
OUT...ESPECIALLY WITH UPSLOPING IN THE HIGHER
ELEVATIONS...DEPENDING ON WHERE SCATTERED SNOW SHOWERS DEVELOP.
THE TROUGH WILL SHIFT EAST OF THE AREA ON SUNDAY...WITH SNOW
SHOWERS DIMINISHING IN COVERAGE AND COMING TO AN END FOR MOST OF
THE AREA BY THE AFTERNOON. MODELS REMAIN IN AGREEMENT THAT HIGH
PRESSURE WILL BUILD IN FROM THE SOUTHWEST BEHIND THIS FEATURE AND
ALLOW FOR A DRY FORECAST SUNDAY NIGHT INTO MONDAY.
FOR TEMPS...A NOTICEABLY COLDER WEEKEND IS AHEAD IN CAA BEHIND THE
FRONT. TEMPS WILL STRUGGLE TO REACH 30 ACROSS THE AREA EACH DAY
WITH TEMPS AROUND 10 TO 15 DEGREES BELOW NORMAL. WAA WILL RETURN
AHEAD OF THE FRONT ON MONDAY...ALLOWING FOR TEMPS TO WARM TO A FEW
DEGREES ABOVE SEASONAL NORMS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A STRONG COLD FRONT WILL PUSH ACROSS THE DISTRICT TUESDAY
BRINGING SHOWERS AND WARMER TEMPERATURES AHEAD OF THE FRONT. AS
THE FRONT PUSHES EAST OF THE DISTRICT RAIN SHOWERS WILL CHANGE TO
SNOW SHOWERS AS COLDER TEMPERATURES MOVE IN FOR TUESDAY NIGHT INTO
WEDNESDAY. NORTHWEST FLOW OFF THE LAKES BEHIND THE FRONT WILL
BRING SOME SNOW SHOWERS WEDNESDAY NIGHT. HIGH PRESSURE WILL BRING
DRY WEATHER FOR THURSDAY. ANOTHER COLD FRONT WILL BRING A RISK OF
SHOWERS FOR FRIDAY.
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
A COLD FRONT MOVING ACROSS THE DISTRICT THIS EVENING WILL BRING
PERIODS OF SNOW WITH MVFR TO IFR RESTRICTIONS WHEN THE SNOW
IS OCCURRING. GENERAL MVFR OVERCAST CEILINGS CAN BE EXPECTED
TONIGHT WHERE NO SNOW IS FALLING. SNOW IS MOST LIKELY ACROSS THE
SOUTHERN PORTS.
.OUTLOOK.../SATURDAY THROUGH WEDNESDAY/...
PERIODIC RESTRICTIONS ARE POSSIBLE THROUGH SUNDAY AS SEVERAL FAST
MOVING DISTURBANCES MOVE ACROSS THE GREAT LAKES REGION. HIGH
PRESSURE AND VFR CONDITIONS ARE FORECAST TO RETURN MONDAY AND LAST
UNTIL A COLD FRONT APPROACHES TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...WOODRUM
LONG TERM...RSD
AVIATION...RSD
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1258 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA THIS AFTERNOON INTO THE EVENING.
THIS SYSTEM WILL PROVIDE SNOW SHOWERS...WHICH MAY MIX WITH RAIN IN
THE SOUTH. IN THE WAKE OF THE FRONT...COLDER TEMPERATURES WITH
SNOW SHOWERS ARE EXPECTED THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO SPEED
UP ONSET OF LIKELY POPS WITH SNOW SHOWERS RELATED TO THE COLD FRONT.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A BROAD 500MB TROUGH
ACROSS THE MIDWEST WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY
FLOW AHEAD OF THIS FEATURE. 700MB OMEGA INDICATES AN AREA OF LIFT
ALONG THE OH/WV BORDER THAT IS SHIFTING NORTHEASTWARD INTO NORTH-
CENTRAL WV. THIS LIFT HAS BEEN SUFFICIENT FOR A MIX OF RAIN AND
SNOW SHOWERS MOVING INTO WV. AT THE SURFACE...A COLD FRONT EXTENDS
FROM ONTARIO SOUTHWARD ACROSS CENTRAL OHIO. WITH THE
FRONT...SCATTERED SNOW SHOWERS ARE MOVING ACROSS THE OHIO VALLEY.
TODAY...THE INITIAL AREA OF 700MB OMEGA WILL SLIDE INTO NORTHERN
WV...SOUTHWEST PA...AND WESTERN MD...WITH A STRONG ENOUGH
1000-900MB MELTING LAYER ALLOWING FOR A RAIN/SNOW MIX TO PUSH
INTO THESE AREAS THROUGH THE EARLY AFTERNOON. PRECIPITATION WILL
BE ALL SNOW ACROSS THE ALLEGHENY FRONT AND LAUREL HIGHLANDS AS
ELEVATION NEGATES THE MELTING LAYER. ANY SNOW ACCUMULATION WITH THIS
WILL BE LIMITED TO THE HIGHER ELEVATIONS AND WILL BE GENERALLY
LESS THAN AN INCH. TEMPS TODAY ARE CLOSEST TO LAMP GUIDANCE WITH THE
HRRR TOO WARM. HIGHS WILL RANGE FROM THE MID 30S ALONG THE I-80
AND EASTERN RIDGES TO THE LOWER 40S IN NORTH-CENTRAL WV.
THE COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND IS
PROGGED TO BE BISECTING THE PITTSBURGH METRO BY 00Z. THE FRONT WILL
BRING SNOW SHOWERS TO THE AREA...CHANGING PRECIPITATION TO ALL
SNOW. WITH WARMER GROUND AHEAD OF THE FRONT AND SHOT OF CAA
LAGGING SOMEWHAT BEHIND THE FRONT...BELIEVE THIS WILL LIMIT
ACCUMULATION. THUS...WITH THE FRONTAL PASSAGE ITSELF...SNOW
ACCUMULATION WILL BE AN INCH OR LESS ACROSS THE AREA.
TONIGHT...THE FRONT WILL SLIDE EAST OF THE AREA AND CAA WILL
ENSUE. BEHIND THE FRONT...A WESTERLY COMPONENT WILL ALLOW FOR SOME
UPSLOPING ACROSS THE LAUREL HIGHLANDS AND ALLEGHENY FRONT
OVERNIGHT. HOWEVER...DEEP MOISTURE WILL NOT BE PRESENT IN THE WAKE
OF THE FRONT AND THUS ANTICIPATE THAT SNOW WILL BE GENERALLY LIGHT
WITH ADDITIONAL OVERNIGHT ACCUMULATION OF 1 TO 2 INCHES FOR
LOCATIONS ABOVE 2000 FT. ACROSS THE LOWLANDS...AN INVERSION AROUND
4-5KFT WILL LIMIT SNOW SHOWERS AND THUS ANTICIPATE LITTLE OR NO
ACCUMULATION OVERNIGHT. WITH A POST-FRONTAL ARCTIC AIR MASS
SETTLING INTO THE REGION...TEMPS TONIGHT WILL BE NOTICEABLY
COLDER. A MAV/MET BLEND WAS USED WITH LOWS RANGING FROM THE MID
TEENS NORTH AND EAST OF PITTSBURGH TO NEAR 20 IN PORTIONS OF
EASTERN OHIO AND NORTHERN WV.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
SNOW SHOWERS WILL REDEVELOP LATER SATURDAY AND CONTINUE INTO
EARLY SUNDAY AS A TROUGH AXIS...ASSOCIATED WITH UPPER LEVEL LOW
OVER THE NORTHERN GREAT LAKES...SWINGS THROUGH. THIS SYSTEM WILL
ALSO PROVIDE ANOTHER REINFORCING SHOT OF COLD AIR.
SNOW SHOWERS WILL DIMINISH ON SUNDAY AS WINDS BACK TO THE WEST AND
SFC HIGH MOVES THROUGH THE MID-ATLANTIC.
TEMPS THROUGH THE WEEKEND WILL BE BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE WILL BRING DRY WEATHER AND SEASONABLE TEMPERATURES FOR
SUNDAY NIGHT INTO MONDAY NIGHT. A STRONG COLD FRONT WILL PUSH ACROSS
THE DISTRICT TUESDAY BRINGING SHOWERS AND WARMER TEMPERATURES AHEAD
OF THE FRONT. AS THE FRONT PUSHES EAST OF THE DISTRICT RAIN SHOWERS
WILL CHANGE TO SNOW SHOWERS AS COLDER TEMPERATURES MOVE IN FOR
TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE WILL BRING A RETURN OF
DRY WEATHER FOR WEDNESDAY NIGHT INTO THURSDAY.
&&
.AVIATION /18Z FRIDAY THROUGH TUESDAY/...
SCATTERED SHOWERS ARE EXPECTED WITH AN UPPER WAVE THIS AFTERNOON.
THE NORTHERN EXTENT OF RESTRICTIONS IN SNOW IS STILL UP FOR DEBATE
BUT MOST LIKELY AT KMGW. THE SNOW COULD REACH AS FAR NORTH AS KPIT
AND KHLG. VFR CEILINGS WILL PREVAIL AT MOST PORTS THIS AFTERNOON WITH
JUST OCCASIONAL MVFR CEILINGS WHERE THE SNOW IS NOT FALLING. SOME
IFR CONDITIONS ARE POSSIBLE WHERE THE SNOW PERSISTS FOR SEVERAL
HOURS.
A STRONGER COLD FRONT SHOULD BRING ANOTHER WIND SHIFT THIS EVENING
ALONG WITH THE POSSIBILITY OF CIGS DROPPING BACK TO MVFR IN MORE
SCATTERED SHOWERS.
.OUTLOOK.../SATURDAY THROUGH TUESDAY/...
PERIODIC RESTRICTIONS ARE POSSIBLE THROUGH SUNDAY AS SEVERAL FAST
MOVING DISTURBANCES MOVE ACROSS THE GREAT LAKES REGION. HIGH
PRESSURE AND VFR CONDITIONS ARE FORECAST TO RETURN MONDAY AND LAST
UNTIL A COLD FRONT APPROACHES TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
AVIATION...RSD
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
113 PM EST FRI FEB 15 2013
.SYNOPSIS...
ISSUED AT 1053 AM EST FRI FEB 15 2013
SNOW WILL INTENSIFY THIS EVENING AND LINGER THROUGH SATURDAY
EVENING. THIS WILL BRING SIX TO NINE INCHES OF SNOW TO THE
LAKESHORE...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. THIS GREATEST
SNOWFALL AMOUNTS ARE EXPECTED MAINLY ALONG THE LAKESHORE COUNTIES.
FARTHER INLAND CLOSER TO THE US-131 CORRIDOR...TOTALS OF 2 TO 5
INCHES WILL BE MORE COMMON...WITH EVEN LESSER AMOUNTS FARTHER
EAST.
THE SNOW WILL DIMINISH INTO SATURDAY NIGHT WITH SOME SUNSHINE
EXPECTED BY SUNDAY. THEN ANOTHER PERIOD OF SNOW IS EXPECTED FOR
MONDAY AND MONDAY NIGHT. WITH MORE SNOW POSSIBLE AGAIN BY THE END
OF THE WORK WEEK.
&&
.UPDATE...
ISSUED AT 1053 AM EST FRI FEB 15 2013
TRIMMED BACK SNOW ACCUMULATIONS TODAY BASED ON LATEST OBSERVATIONS
AND MODEL GUIDANCE. LATEST RUNS OF THE RAP MODEL SUGGEST ACCUMULATING
SNOW WILL BE DELAYED UNTIL AFTER 6 TO 7 PM TONIGHT. ALSO LOWERED
INLAND SNOW AMOUNTS OVERALL AS WE EXPECT A FAIRLY SHARP DROP OFF
IN ACCUMULATIONS AWAY FROM THE LAKE SHORE BASED ON THE REASONING
IN THE PREVIOUS DISCUSSION REGARDING CROSS HAIR SIGNATURE
PLACEMENT AND LIKELY INLAND CELLULAR NATURE OF PRECIPITATION
SATURDAY. WILL BE ISSUING AN ADVISORY UPDATE SHORTLY TO REFLECT
THIS CHANGE IN THINKING.
WE ARE LOOKING AT THE POTENTIAL FOR SIGNIFICANT SNOWFALL ENHANCEMENT
ACROSS OUR NORTHERN ZONES AFTER MIDNIGHT AS THE NAM SUGGESTS A
MESOLOW WILL ZIP SOUTHEAST THROUGH LUDINGTON. THIS WILL BE
SOMETHING TO WATCH FOR THE AFTERNOON UPDATE.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 342 AM EST FRI FEB 15 2013
HAVE DECIDED TO GO WITH A LAKE EFFECT SNOW ADVISORY FOR ROUGHLY THE
WESTERN HALF OF THE CWA STARTING LATE THIS AFTERNOON AND CONTINUING
INTO SATURDAY EVENING.
LONG DURATION LAKE EFFECT EVENT WILL RAMP UP LATE THIS AFTERNOON A
STRONG WAVE ENERGY PIVOTS IN. INVERSION HEIGHTS WILL CLIMB LEADING
TO AN INCREASED INTENSITY TO THE THE SNOW SHOWERS. FAVORABLE OMEGA
CROSS HAIR SIGNATURE WITHIN THE DGZ LINES UP ALONG THE LAKE SHORE
COUNTIES BY THIS EVENING AND REMAINS PERSISTENT RIGHT INTO SATURDAY
EVENING. MEAN FLOW WILL WAVER SOMEWHAT...SO NOT SURE HOW PERSISTENT
THE SNOW WILL BE AT ANY ONE SPOT...HENCE THE ADVISORY VERSUS A
WARNING. THE FLOW WILL BE 290-300 MUCH OF TONIGHT...BUT THEN IT
BECOMES 310-340 FOR SATURDAY/SATURDAY EVENING WHICH WILL SHIFT THE
SNOW BANDS A BIT.
ANOTHER CONSIDERATION WILL BE THE IMPACT OF THE HIGHER SUN ANGLE
THIS TIME OF YEAR. WE ARE GETTING INTO THAT TIME OF YEAR WHERE THE
LAKE EFFECT CAN BECOME MORE CELLULAR DUE TO DAYTIME CONVECTIVE
ELEMENTS. THIS COULD ALSO LOWER ACCUMS A BIT...OR AT LEAST AFFECT A
PERSISTENT DAYTIME HEAVY SNOW BAND.
ALL IN ALL...EXPECT SOME AREAS ALONG THE LAKE SHORE COUNTIES MAY SEE
UP TO NINE INCHES OF SNOW OVER THE 30 HOUR HEADLINE PERIOD. AMOUNTS
WILL LOWER FURTHER INLAND...BUT THE U.S. 131 COUNTIES WILL STILL SEE
A PERSISTENT SNOW WITH 4 TO 8 INCHES POSSIBLE THERE. EASTERN
COUNTIES WILL SEE SNOW TOO DUE THE SYNOPTIC SHORT WAVE AND SOME LAKE
ENHANCEMENT. FEEL A 2 TO 4 INCH ACCUM SHOULD OCCUR OVER THE SAME
30 HOUR PERIOD.
OTHERWISE...UNTIL WE SEE THE RAMP UP LATE THIS AFTERNOON...THE SNOW
SHOWERS WILL CONTINUE ON A LIGHTER RATE. INVERSION LEVELS STAY
AROUND 5K FEET UNTIL THE SHORT WAVE ARRIVES.
.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 342 AM EST FRI FEB 15 2013
TWO STORMS ARE EXPECTED NEXT WEEK AND THE SECOND ONE COULD BE MAJOR.
FIRST UP...A CLIPPER MOVES TOWARDS LOWER MICHIGAN ON MONDAY WHILE
PHASING WITH A SOUTHERN STREAM LOW RIGHT OVER LOWER MICHIGAN.
FORECAST CONFIDENCE IS HIGH IN THAT THE MODELS HAVE AGREED ON A RAIN
AND SNOW MIX MOVING IN LATE MONDAY...CHANGING TO SNOW MONDAY NIGHT.
THIS IS FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY
AFTERNOON INTO WEDNESDAY.
SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON
WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM
APPEARS TO BE TAKING SHAPE ACROSS THE PLAINS. THE GULF IS WIDE OPEN
FOR THIS ONE AND A COLD SFC HIGH IS IN PLACE ACROSS EASTERN CANADA.
MODELS HAVE SHOWN THIS STORM FOR A COUPLE DAYS NOW WITH PRETTY GOOD
CONSISTENCY. THURSDAY COULD SEE THE ONSET OF THE STORM WITH SNOW
BREAKING OUT LATE IN THE AFTERNOON...ALTHOUGH BOTH THE GFS AND ECMWF
SHOW THE HEAVIER SNOW NOT ARRIVING UNTIL THURSDAY NIGHT OR FRIDAY.
EVEN AT THIS LONG RANGE THE MODELS ARE SHOWING STRONG F-GEN
POTENTIAL SO THIS COULD BE THE BIGGEST SYNOPTIC SNOW EVENT OF THE
WINTER SO FAR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 113 PM EST FRI FEB 15 2013
MAIN FOCUS OF THE 18Z FCSTS IS LAKE EFFECT TRENDS THROUGH THE
PERIOD. LIGHT LAKE EFFECT IS CURRENTLY OCCURRING ACROSS THE AREA
THIS AFTERNOON. OBVIOUSLY THE BEST CONCENTRATION IS CLOSER TO THE
LAKESHORE SOUTH OF KMKG AND WEST OF KGRR. NOT A LOT OF MESOSCALE SUPPORT
THIS AFTERNOON FOR LAKE EFFECT...WHICH IS LEADING TO CONDITIONS
REMAINING MVFR OR BETTER. WE EXPECT THAT THE LAKE EFFECT WILL
INTENSIFY LATER THIS EVENING AND ESPECIALLY OVERNIGHT...ESPECIALLY
AT THE FOUR MOST WRN TERMINALS. IFR WILL BECOME LIKELY AS
CONDITIONS BECOME MORE FAVORABLE FOR LAKE EFFECT. KLAN AND KJXN
WILL SEE LESS IN THE WAY OF IMPACT.
LAKE EFFECT SHOULD DIMINISH INLAND MID MORNING ON SAT AS THE FLOW
BECOMES MORE NW AS A LOW PUSHES AWAY FROM THE AREA. KAZO WILL BE
THE MOST IMPACTED TERMINAL WITH CONTINUED POSSIBLE IFR WITH THE NW
FLOW.
&&
.MARINE...
ISSUED AT 1053 EST FRI FEB 15 2013
KEPT THE SMALL CRAFT ADVISORY INTACT...BUT THERE ARE INDICATIONS
WE WILL STAY BELOW THRESHOLDS AFTER THIS EVENING. WE ARE CONSIDERING
SCALING BACK THE DURATION OF THE SCA FOR THE AFTERNOON UPDATE.
&&
.HYDROLOGY...
ISSUED AT 342 AM EST FRI FEB 15 2013
ONLY ONE FLOOD ADVISORY REMAINS ON THE PERE MARQUETTE AT
SCOTTVILLE. THIS IS EXPECTED TO REMAIN FAIRLY STEADY OVER THE SHORT
TERM. OTHERWISE WITH THE POLAR AIR COMING IN ANY MELT OFF HAS ENDED
THROUGH AT LEAST THE WEEKEND.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST SATURDAY FOR MIZ037-
043-050-056-064-071-072.
LAKE EFFECT SNOW ADVISORY FROM 10 PM THIS EVENING TO 7 PM EST
SATURDAY FOR MIZ038-044-057-065-073.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...JK
LONG TERM...OSTUNO
AVIATION...NJJ
HYDROLOGY...JK
MARINE...TJT
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1231 PM EST FRI FEB 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 458 AM EST FRI FEB 15 2013
THE LOW THAT AFFECTED THE SOUTHERN PART OF THE CWA YESTERDAY MORNING
HAS LEFT A SURFACE TROUGH OVER EASTERN LAKE SUPERIOR. RUC ANALYZED
850MB TEMPS ARE AROUND -16C OVER LAKE SUPERIOR AND NORTH-NORTHWEST
WINDS ALOFT HAS LED TO LAKE EFFECT SNOW OVER PORTIONS OF LAKE
SUPERIOR EARLY THIS MORNING. THE BEST SNOW HAS BEEN OCCURRING OVER
IN THE MULTI-BANDED SNOW OVER EASTERN LAKE SUPERIOR...WHERE
INVERSION HEIGHTS ARE AROUND 8KFT BASED OF KMQT RADAR AND THERE IS
ENOUGH MOISTURE PRESENT. FARTHER WEST...DRIER AIR THIS EVENING HAS
LIMITED MUCH OF THE LAKE EFFECT SNOW THUS FAR. BUT WITH A SHORTWAVE
JUST NORTHWEST OF LAKE SUPERIOR EXPECTED TO INCREASE MOISTURE ACROSS
THE AREA...HAVE SEEN A SLIGHT INCREASE IN COVERAGE ON SATELLITE
BETWEEN THE HIGHER CLOUDS. THIS WILL ALSO INCREASE THE INVERSION
HEIGHTS FROM 3-4KFT TO 6-8KFT OVER THE WEST. THUS...EXPECT THE LAKE
EFFECT TO TO CONTINUE TO INCREASE IN INTENSITY/COVERAGE FOR BOTH
WEST/EAST THROUGH THE MORNING HOURS FOR LOCATIONS FAVORED BY
NORTH-NORTHWEST WINDS. WITH MUCH OF THE CONVECTIVE PORTION OF THE
CLOUD WITHIN THE DGZ...EXPECT VERY FLUFFY LAKE EFFECT AND SNOW
RATIOS IN THE 30-1 RANGE. THIS WILL ALLOW FOR QUICK ACCUMULATIONS IN
THE STRONGER BANDS...ESPECIALLY SINCE WINDS WILL HAVE DECREASED FROM
THE 20-30KTS SEEN AROUND MIDNIGHT. ONE ITEM OF CONCERN FOR THE
INTENSITY THIS MORNING OVER THE WEST...ESPECIALLY OVER THE
KEWEENAW...IS THE 30 DEGREES OF SHEAR BETWEEN THE TOP OF THE
INVERSION /800MB/ AND THE MIDDLE OF THE CONVECTIVE CLOUD /900MB/.
THIS MAY LIMIT THE DEEP AND ORGANIZED BANDS THAT WOULD PROMOTE VERY
HEAVY SNOW.
AS THIS SHORTWAVE DEPARTS LATE THIS MORNING AND INTO THE
AFTERNOON...WOULD THINK THE LAKE EFFECT WILL DIMINISH SOME AS
DIURNAL MIXING HELPS REDUCE THE INTENSITY OF THE BANDS OVER THE
WEST. IN ADDITION...THE DEEPER MOISTURE SLIDES MORE OVER THE EASTERN
LAKE WHILE WINDS BACK TO THE NORTHWEST. THIS WILL HELP REDUCE THE
INTENSITY OF THE BANDS SLIGHTLY...BUT THE BACKING WINDS WILL CAUSE
THE HEAVIEST SNOW TO SHIFT FROM THE MORE NNW FAVORED AREAS TO NW
AREAS. ALTHOUGH THIS WILL SPREAD THE LAKE EFFECT TO MORE AREAS...IT
MIGHT CAUSE SOME LIMITATION IN THE HIGHER SNOWFALL AMOUNTS IN ONE
LOCATION TO BE PRIMARILY IN THE ADVISORY CRITERIA CATEGORY. HIGHER
RESOLUTION MODELS DO PICK UP ON BOTH OF THESE FEATURES WELL AND
WILL FOLLOW THEIR TIMING FOR THE MOVEMENT AND INTENSITY FOR THIS
AFTERNOON. OVER THE EAST...INVERSION HEIGHTS OVER THE EAST RISE TO
8-10KFT THIS AFTERNOON AND CONTINUE INTO THE EVENING. WITH THE
DEEPER MOISTURE FROM THE SHORTWAVE AND SOME ENHANCED CONVERGENCE ON
THE SOUTHWEST EDGE OF THE LAKE EFFECT...EXPECT A FAIRLY HEAVY BAND
OR TWO WITHIN THE MULTI-BAND SNOW TO SETUP SOMEWHERE BETWEEN
MUNISING AND GRAND MARAIS. THIS NW WIND WILL ALSO LEAD TO
AN INCREASED PERIOD OF SNOW FOR NORTHERN LUCE COUNTY LATER THIS
AFTERNOON AND INTO THE EARLY EVENING. THIS IS DUE TO THE LONGER
FETCH THAN THEY WILL SEE FOR THE FIRST PART OF TODAY WITH THE
NORTHERLY WINDS. THERE IS THE POTENTIAL FOR SOME HEAVIER SNOWFALL
RATES AND ADVISORY SNOWFALL DURING THAT PERIOD...SO FELT
COMFORTABLE ISSUING AN ADVISORY EVEN THOUGH THERE IS SOME CONCERN
ON THE TIMING OF WHEN THE BAND WILL BACK TO THE WEST TONIGHT AS
WINDS SHIFT TO THE NORTHEAST.
COLDER AIR ARRIVES TONIGHT...WITH 850MB TEMPS FALLING TOWARDS -22C
OVER THE WEST AND -20C OVER THE EAST. OVER THE WEST...THE PRODUCES
SOME CONCERN AS IT WILL PUT A PORTION OF THE CONVECTIVE CLOUD LAYER
AT THE TOP OF OR ABOVE THE DGZ AND LIKELY REDUCE THE SNOW RATIOS
SOMEWHAT. BUT INCREASED CONVERGENCE AS WINDS VEER TO A MORE
NORTHERLY DIRECTION DURING THE EVENING...DUE TO THE APPROACHING HIGH
IN THE NORTHERN PLAINS...WILL HELP INCREASE THE
INTENSITY OF THE SNOW BEFORE RETURNING TO MORE OF A GENERAL
MULTI-BAND LAKE EFFECT DURING THE OVERNIGHT HOURS. ALSO...ANOTHER
WEAK SHORTWAVE IN THE UPPER TROUGH WILL HELP INCREASE MOISTURE AND
KEEP INVERSION HEIGHTS IN THE 7-8KFT RANGE.
OVER THE EAST...THERE DOES SEEM TO BE A SLIGHT SLOWDOWN TO THE
WESTWARD TRANSITION OF THE LAKE EFFECT FROM THE NORTHWEST FAVORED
AREAS TO MORE NORTHERLY COMPARED TO 24HRS AGO...AS THE SURFACE
TROUGH OVER EASTERN LAKE SUPERIOR WEAKENS AND LAND BREEZE INFLUENCES
OFF ONTARIO TAKE OVER. SOME OF THE HIGHER RESOLUTION MODEL RUNS EVEN
TRY TO DEVELOP A WEAK MESO-LOW...WHICH WOULD COMPLICATE MATTERS
FURTHER. THUS...HAVE SLOWED THE WESTWARD TRANSITION A TOUCH AS THE
STRONGER BANDS MAKE THE WESTWARD TRACK ACROSS ALGER AND NORTHERN
SCHOOLCRAFT COUNTIES DURING THE NIGHT. THE INCREASED CONVERGENCE
WITHIN THIS BAND SHOULD LEAD TO SOME HEAVY SNOWFALL RATES AS IT
TRANSITIONS TO THE WEST.
ALL IN ALL...WILL LEAVE THE WARNING HEADLINES AS IS AND ADD
THE LUCE ADVISORY. THERE IS SOME SLIGHT CONCERN ON GETTING WARNING
AMOUNTS IN A WIDESPREAD AREA OF GOGEBIC/ONTONAGON
COUNTIES...BUT SHOULD EASILY SEE THE 12 INCHES IN 24HRS OVER
THE PORKIES. THE ONE QUESTION TO CARRY FORWARD TO THE DAY SHIFT IS
THE BORDERLINE ADVISORY SNOW FOR NORTHERN HOUGHTON AND KEWEENAW
COUNTIES. DIDN/T HAVE A GOOD FEELING ON ADVISORY AMOUNTS FOR
TODAY...ALTHOUGH WITH THE FLUFFY NATURE...COULD SEE A QUICK 4 INCHES
IN A LOCATION IF A BAND SETS UP FOR A FEW HOURS THIS MORNING. IN
ADDITION...WITH THE WINDS BACKING TO THE NW THIS AFTERNOON AND THEN
MORE OUT OF THE NORTH TONIGHT...WOULDN/T THINK THEY WOULD SEE A
PERSISTENT AREA OF TO RAISE CONFIDENCE ENOUGH FOR AN ADVISORY AT
THIS TIME. WITH THE MORE FAVORABLE MOISTURE TONIGHT AND SOME
ENHANCED CONVERGENCE...WOULD THINK THE BEST POTENTIAL FOR ADVISORY
SNOW WOULD BE OVER NORTHERN HOUGHTON COUNTY TOWARDS TWIN LAKES AND
THE DAY SHIFT MAY NEED TO SEE IF THAT IDEA CONTINUES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 458 AM EST FRI FEB 15 2013
SATURDAY...HIGHER RES MODELS SUGGEST THAT LAKE INDUCED TROUGHING WILL
FOCUS STRONGEST LOW LEVEL CONV AND LES INTO NORTH CENTRAL UPPER MI
BTWN MARQUETTE AND MUNISING. CONTINUED HIGH SLR NEAR 30/1 WOULD
SUPPORT SOME SNOW TOTALS IN THE 4 TO 7 INCH RANGE. CONFIDENCE IN THE
LOCATION OF THIS MESO SCALE FEATURE IS LIMITED BUT A HEADLINE FOR THE FAR
EASTERN PORTION OF MARQUETTE COUNTY MAY BE NECESSARY IF MODEL
AGREEMENT IS CONSISTENT. OVER THE WEST...LES WILL DIMINISH MORE
QUICKLY WITH THE SFC RIDGE AND DRIER AIR BUILDING INTO THE AREA
LEADING TO ADDITIONAL TOTALS ONLY IN THE 1 TO 4 INCH RANGE. A SHALLOW
DGZ WITH LESS FAVORABLE SLR WOULD ALSO LIMIT ACCUMULATION POTENTIAL.
SAT NIGHT...ALTHOUGH LES WILL CONTINUE TO DIMINISH WITH THE RIDGE
BUILDING INTO THE AREA...LIGHT WIND FIELDS AND CONTINUED LOW LEVEL
CONV...ESPECIALLY NEAR THE SHORELINE VCNTY KP53 COULD PRODUCE
SEVERAL ADDITIONAL INCHES OF SNOW. OTHERWISE...CLEARING WITH
FAVORABLE RADIATIONAL COOLING CONDITIONS WILL SUPPORT MIN TEMPS NEAR
THE LOWER END OF GUIDANCE...INTO THE -15F TO -20F RANGE INTERIOR
WEST HALF.
SUN AND SUN NIGHT...A PROGRESSIVE PATTERN WITH THE SFC RIDGE
SHIFTING TO THE EAST...A TROUGH INTO THE NRN PLAINS TO THE UPPER MS
VALLEY AND A STRENGTHENING WAA PATTERN WILL ALLOW MOISTURE TO
INCREASE. BOTH THE GFS AND ECMWF SUGGEST THE STRONGEST ISENTROPIC
LIFT WILL REMAIN NORTH OF THE CWA WITH ONLY CHANCE POPS FOR LIGHT
SNOW BY LATE SUN NIGHT.
MON INTO MON NIGHT...MODELS WERE SIMILAR WITH A MID/UPPER LEVEL
TROUGH INTO THE WRN GREAT LAKES. THE ECMWF WAS A BIT SLOWER AND MORE
AGGRESSIVE IN DIGGING THE TROUGH AND SFC LOW TO THE SOUTH COMPARED
TO THE GFS...BUT NOT AS MUCH AS THE CMC...RESULTING IN GREATER PCPN
ACROSS UPPER MICHIGAN. WITH SUFFICIENT MOISTURE INFLOW BRINGING PWAT
TO NEAR 200 PCT NORMAL THE POTENTIAL REMAINS FOR MODERATE SNOW
ACCUMULATIONS WITH THE SYSTEM.
TUE-WED...SIGNFICANT/HEAVY LES WILL BE POSSIBLE IN THE WAKE OF THE
LOW WITH STRONG CAA DROPPING 850 MB TEMPS INTO THE -15C TO -20C
RANGE ALONG WITH CYCLONIC NNW FLOW AND ABUNDANT 850-700
MOISTURE...PER ECMWF. LES SHOULD DIMINISH WED AS RIDGING AGAIN
BUILDS INTO THE REGION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1227 PM EST FRI FEB 15 2013
LAKE EFFECT SNOW SHOWERS WILL CONTINUE AT ALL SITES. EXPECT THE
STRONGEST SNOW THROUGH MUCH OF THE DAYTIME HOURS AT KIWD WITH THE
MORE FAVORABLE AND CONVERGENT FLOW EARLY THIS AFTERNOON. BUT AS
WINDS BACK MORE TO THE NORTHWEST...EXPECT CONDITIONS TO BECOME LESS
FAVORABLE AT KIWD. EXPECT PERIODS OF ALTERNATE LANDING MINIMUMS
VISIBILITIES TONIGHT AS LOW LEVEL CONVERGENCE INCREASES WITH WINDS
VEERING TO THE NNW...INCREASING THE INTENSITY OF THE SNOW.
AT KSAW...UNFAVORABLE DOWNSLOPING NW FLOW WILL GENERALLY KEEP
BORDERLINE MVFR/VFR CEILINGS THROUGH THE PERIOD WITH OCCASIONAL
SNOW SHOWERS FROM ENHANCED SNOW OFF THE HURON MOUNTAINS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 AM EST FRI FEB 15 2013
NORTHWEST WINDS OF 20-30KTS WILL DIMINISH TODAY AS HIGH PRESSURE IN
THE NORTHERN PLAINS SLOWLY SHIFTS EAST INTO THE UPPER GREAT LAKES.
THIS WILL CONTINUE TO DIMINISH THE WINDS ON THROUGH SATURDAY.
BEFORE THE WINDS DIMINISH...HEAVY FREEZING SPRAY IS EXPECTED OVER
PORTIONS OF LAKE SUPERIOR THROUGH TONIGHT. AS THE HIGH SHIFTS EAST
ON SUNDAY A LOW PRESSURE SYSTEM WILL APPROACH THE UPPER GREAT LAKES
ON MONDAY AND MOVE THROUGH ON TUESDAY. THIS WILL BRING INCREASING
SOUTHERLY FLOW ON MONDAY...TO 25KTS OVER THE EAST...AND THEN STRONG
NORTHERLY WINDS BEHIND THE LOW ON TUESDAY AFTERNOON...TO 30KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SATURDAY FOR MIZ006-085.
LAKE EFFECT SNOW ADVISORY UNTIL 5 AM EST SATURDAY FOR MIZ007.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST /NOON CST/ SATURDAY FOR
MIZ002-009.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR
LSZ264>266.
HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR
LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...JLB
AVIATION...TITUS
MARINE...SRF
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
412 PM CST FRI FEB 15 2013
.DISCUSSION...
Short Range (Tonight through Sunday)...
Main weather concern for this period centers on the overnight period
but confined to only the western third of the CWA. One last
vorticity max/shortwave diving down the backside of a retreating
broad upper trough will drop south-southeast across eastern NE
passing just west of the MO/KS state line overnight. Satellite
imagery and radar returns suggest two vorticity maxima...one moving
into northeast NE and a second west of BIE. Features are best seen
on NAM h7 prog. Scattered snow showers a bit more widespread than
shown by NAM output while RAP looks too generous on qpf. Prefer
blending the two model outputs which results in higher pops and
expanding snow shield a bit more east. Moderately high liquid/snow
ratios show potential for a narrow swath of 1+ inches of snow over
the far western counties. Given the expected scattered coverage of
the snow prefer keeping pops under the likely category for now. Snow
will have exited the southwestern CWA by Saturday morning with
clearing from north to south.
Saturday will bring the start of a welcome warmup over the Plains
which will quickly spread east...reaching into the western counties
by the afternoon hours. A band of dense mid level clouds will spread
from west to east Saturday night and herald the arrival of the
deepening warm air advection zone. Still expecting a significant
warmup on Sunday although there may be a tighter west to east
gradient due as boundary layer winds take on a south-southeast
direction which will limit the degree of warming further east.
MJ
Medium Range (Monday through Friday)...
Next week continues to look very active, with two systems moving
through the Plains on Monday night and again from Wednesday night
through early Friday. The primary focus will be the significant
system for Wednesday night through Thursday night, which has the
potential to be a fairly major winter storm if the current track
pans out.
On Monday, a deep longwave trough will dive through the Central
Plains, driving a surface cold front through the CWA during the
daylight hours. A broad area of scattered rain showers will be
possible along and ahead of the front, but amounts will be light as
moisture return into the Plains will be quite limited. A brief mix
with snow may be possible along our eastern border if any light
precipitation can linger behind the surface boundary, but no snow
accumulation is expected.
By Wednesday night, a deep upper low will begin to eject out of the
four corners region. As it moves eastward into the southern Plains,
strong southerly flow will draw Gulf moisture into the system, which
will combine with the existing Pacific moisture and enhance
precipitation coverage and intensity as the system begins to lift
northeast. All model solutions bring the elevated warm front into at
least the southeastern two thirds of the CWA by Thursday morning but
keep cold air lingering at the surface over almost the entirety of
the area, indicating a potential for freezing rain in those areas.
Since this is a deviation from previous forecasts, have started out
with a slight chance for freezing rain on top of the primary
rain/snow mix, but the probability for ice may need to be heightened
if future forecasts look similar. As cold air wraps in behind the
850mb low, precipitation should change to all snow from west to east
during the day on Thursday, becoming all snow and lifting out of the
area after 00z Friday. Very preliminary snowfall totals range from
more than 6 inches across the northern third of the forecast area
where precipitation type is likely to be snow during the majority of
the event, to 2-3 inches in west central and eastern parts of the
CWA, then tapering to less than 2 inches in the far southwest where
rain or freezing rain will be the predominant precipitation type
during the majority of the event.
With the consistency of model solutions, both temporally and between
different model configurations, the overall potential for a winter
storm is increasing. However, precipitation types and snowfall
amounts are still somewhat uncertain and will need to be further
refined, especially as this system heads onshore early next week.
Laflin
&&
.AVIATION...
For the 18z TAF...VFR conditions will continue into early this
evening although mid level cigs will move in around sunset in
advance of an approaching vorticity maxima. Satellite imagery
suggests this feature is loosely held together as it moves into
northeast NE. System is best modeled at 700mb with the NAM tracking
the center across eastern KS tonight. Narrow swath of snow expected
to fall close the the vorticity center. Low confidence on
accumulating snow reaching the terminals so have improved
visibilities and raised cigs to high end MVFR. Better bet for lower
cigs/vsbys and snow will be over eastern KS. Looks like a 3-5 hour
window for snow threat.
MVFR cigs will improve to VFR Saturday morning as winds back from
north to west indicating warm air advection process beginning.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1122 AM CST FRI FEB 15 2013
.UPDATE...
ISSUED AT 919 AM CST FRI FEB 15 2013
UPDATED FORECAST TO REMOVE FLURRIES AND CLEAR SKIES FOR TODAY.
CVKING
&&
.SHORT TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TODAY)
EARLY MORNING RUC ANALYSES OF THE 1.5 PVU SFC COMBINED WITH WATER
VAPOR IMAGERY DEPICTED A REASONABLY STRONG PV ANOMALY MOVING ACROSS
NRN MO. THIS FEATURE IS EXPECTED TO CONTINUE MOVING ACROSS THE AREA
TODAY WITHIN A BROADER PATTN OF NW FLOW ALOFT. DESPITE THE PRESENCE
OF A FORCING MECHANISM...THE LIMITING FACTOR FOR MEASURABLE PCPN
TODAY WILL BE MOISTURE GIVEN THE FAIRLY DRY LOW AND MID LEVELS AS
WELL AS DECREASING PW VALUES THROUGH THE DAY. AT THE SFC...A CDFNT
WAS LOCATED FM CENTRAL KS THROUGH NRN MO INTO NRN IL AT 06Z. THIS
FRONT WILL CONTINUE MOVING SEWD TODAY...LEADING TO A COMPLICATED
FCST OF TEMPERATURE TRENDS DUE TO THE COMPETING FACTORS OF LOW LEVEL
CAA...POTENTIAL MIXING ABOVE 900 MB...AND THE EFFECTS OF POSTFRONTAL
CLOUDINESS DURING THE LATE MORNING FOLLOWED BY ADDITIONAL CLOUDS
ADVECTING SWD DURING THE LATE AFTN.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 303 AM CST FRI FEB 15 2013
(TONIGHT THROUGH SUNDAY)
SHORT RANGE MODELS ARE MAINTAINING GOOD RUN TO RUN CONTINUITY
WITH SYNOPTIC FEATURES HEADING INTO THE WEEKEND. ANOTHER SHORTWAVE
WILL DROP SOUTH ACROSS THE PLAINS TONIGHT ON THE BACK SIDE OF THE
UPPER LEVEL TROF...BRINGING A REINFORCING SHOT OF COLD AIR TO THE
AREA FOR SATURDAY. DYNAMICS WITH THIS FEATURE SHOULD CONFINE ANY
PRECIP THREAT TO THE WEST OF OUR CWA...BUT WITH DIRTY NW FLOW AND
MEAN TROF AXIS REMAINING PARKED OVER AREA WE SHOULD CERTAINLY SEE
SOME CLOUDINESS OVERNIGHT AND AT LEAST INTO SATURDAY MORNING.
TEMPERATURE TRENDS IN GOING FORECAST STILL LOOK PRETTY GOOD. THIS
AMS IS FAIRLY CHILLY BUT DUE TO THE EXPECTED CLOUDS OVERNIGHT I HAVE
FOUGHT THE TEMPTATION TO GO TOO COLD...AND STILL HAVE LOWS IN THE
UPPER TEENS TO LOWER 20S. HIGHS SHOULD REBOUND INTO THE L-M30S ON
SATURDAY.
TROF IS STILL ON SCHEDULE TO SWING INTO THE EASTERN U.S. ON SUNDAY.
THIS WILL ALLOW A RAPID TEMPERATURE MODERATION OVER THE CWA...
WITH HIGHS RANGING FROM THE MID 40S OVER OUR E COUNTIES...TO THE
MID 50S OVER MID MO.
(MONDAY-THURSDAY)
ITS PROBABLY A BIT OF AN UNDERSTATEMENT TO SAY THAT THE UA PATTERN
OVER THE CONUS WILL BE ACTIVE FOR MUCH OF NEXT WEEK...WITH THE VERY
AMPLIFIED AND PROGRESSIVE PATTERN PROGGED TO BRING TWO STORM
SYSTEMS INTO THE CENTRAL U.S. MEDIUM RANGE SOLUTIONS ARE
REMAINING IN REMARKABLE RUN TO RUN AND MODEL TO MODEL AGREEMENT
WITH THE TIMING OF THESE SYSTEMS...WITH THE FIRST IMPACTING THE
REGION ON MONDAY AND MONDAY NIGHT AND THE SECOND...AND PROBABLY
STRONGER...SYSTEM ARRIVING LATE WEDNESDAY AND THURSDAY.
MONDAY AND MONDAY NIGHT`S SYSTEM WILL PRIMARILY BE A RAIN
EVENT...WITH THE BULK OF THE PRECIP SHUTTING DOWN ON MONDAY NIGHT
WITH THE ARRIVAL OF THE COLD AIR PREVENTING ANY SIGNIFICANT PERIOD
OF SNOWFALL. SOLUTIONS HAVE NOT BACKED OFF OF THE THINKING THAT
MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM AND DYNAMICS WILL BE
STRONG...SO LIKELY POPS OVER MOST OF THE CWA STILL LOOK LIKE A GOOD
CALL.
ANOTHER SHOT OF COLD AIR IN THE WAKE OF MONDAY`S SYSTEM WILL DROP
TEMPS BACK TO BELOW AVERAGE LEVELS FOR TUESDAY AND WEDNESDAY...AND
THIS COLD AIR WILL SET THE STAGE FOR THE BIG QUESTION MARK FOR
THURSDAY`S SYSTEM...WHICH IS PTYPE. IT CERTAINLY APPEARS THAT THE
FIRST SHOT OF PRECIP INTO THE AREA LATE WEDNESDAY NIGHT AND THURSDAY
MORNING ASSOCIATED WITH INITIAL SURGE OF WARM ADVECTION WILL LIKELY
BE SNOW...BUT PRIMARY QUESTION IS WHAT PTYPES WILL DO DURING THE DAY
ON THURSDAY. OPERATIONAL GFS AND ECMWF ARE BOTH PROGGING VERY
STRONG 850 WAA INTO THE CWA BUT 850 TEMPS...ON BOTH SOLUTIONS...
APPEAR TO BE VERY RELUCTANT TO WARM DURING THE DAY. THIS TREND
LOOKS TO BE TOO COLD GIVEN PLACEMENT OF 850 LOW AND STRENGTH OF
WAA....BUT IT IS PROBABLY A STRONG SIGNAL THAT BOTH MODELS ARE
SUGGESTING THAT THE EVAPORATIVE COOLING THAT DEVELOPS WITH THE
ONSET OF PRECIP WILL BE TOUGH TO OVERCOME.
IF THE CONSENSUS OF THESE SOLUTIONS AND THE LATEST GFS ENSEMBLE
VERIFY...PTYPE WOULD BE ALL SNOW IN THE FAR NORTH AND ALL RAIN IN
THE FAR SOUTH...BUT OVER MOST OF THE CWA PTYPE COULD GO EITHER
WAY. AS MENTIONED BY THE DAY SHIFT YESTERDAY PTYPE FORECASTS WILL
LIKELY BE CHANGING SEVERAL TIMES AS THE EVENT GETS CLOSER IN
TIME...AND SINCE THE STORM IS STILL 7 DAYS OUT WILL MAINTAIN A
BROAD BRUSH APPROACH FOR PTYPE.
TRUETT
&&
.AVIATION...
ISSUED AT 1112 AM CST FRI FEB 15 2013
VFR CONDITIONS ARE EXPECTED. THE NEXT UPPER LEVEL DISTURBANCE
DROPPING SOUTHEAST FROM EASTERN NEBRASKA AND SOUTH DAKOTA WILL
BRING A PERIOD OF MOSTLY MID LEVEL CLOUDS TO THE REGION THIS
EVENING AND EARLY SATURDAY MORNING. UPSTREAM OBSERVATIONS SHOWS A
SMALL AREA OF MVFR CEILINGS AT THE CORE OF THE SYSTEM...WITH EVEN
A FEW FLURRIES. MODELS SUGGEST THAT ANY CHANCE OF MEASURABLE SNOW
AND LOWER CEILINGS WILL REMAIN WEST OF THE CWA. FAST UPPER LEVEL
FLOW WILL MEAN SKIES WILL CLEAR FROM THE NORTHWEST BY DAYBREAK
ACROSS THE CWA. WIND WILL REMAIN NORTHWEST AROUND 10KT.
SPECIFICS FOR KSTL...
VFR CONDITIONS WITH A PERIOD OF MID CLOUDS THIS EVENING. WIND
REMAINS NORTHWEST AROUND 10KT.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1145 AM EST FRI FEB 15 2013
.SYNOPSIS...
A WEAK WAVE PASSING TO OUR SOUTH WILL SPREAD SOME LIGHT RAIN AND
SNOW OVER THE SOUTHERN PARTS OF THE REGION LATE TODAY AND
TONIGHT. A COLD NORTHWEST FLOW WILL PREVAIL FOR THE REMAINDER OF
THE WEEKEND WITH SCATTERED LAKE EFFECT SNOW SHOWERS AND FLURRIES.
SOME MODERATION IN TEMPERATURES IS EXPECTED EARLY NEXT WEEK WITH
ANOTHER FRONTAL SYSTEM EXPECTED TO APPROACH BY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATYEST NAM AND SREF 09Z RUNS HAVE NUDGED PRECIP ACCUMS HIGHER
THAN PREV SOLNS. HRRR AND NEWEST RUC SUPPORT THE EVOLUTION IN NAM
STYLE ALSO. WILL NUDGE SNOW ACCUMS UP JUST ABOUT 50PCT FOR THE
EVENING...BUT HOLD OFF ON ENOUGH OF A BUMP TO PASS THOUGH THE ADVY
THRESHOLD. KEEPING FCST DOWN AT 1-3 INCHES FOR YORK AND LANCASTER
COS. OTHERWISE NO CHANGES.
THE BIGGEST SHORT TERM FORECAST PROBLEM WILL CENTER ON A WAVE OF
LOW PRESSURE THAT THE MODELS WANT TO SEE DEVELOP ALONG THE WEAK
FRONT THAT WILL BE MOVING THROUGH VIRGINIA. THE GFS IS THE MOST
AGGRESSIVE SNOW MAKER WITH THIS SYSTEM...IMPLYING THAT ADVISORY
SNOWS ARE POSSIBLE OVER THE LOWER SUSQ VALLEY FROM ABOUT ADAMS
COUNTY EASTWARD. THE GEFS IS TAMER...WITH AN INCH OR TWO INDICATED
IN THE THREATS OUTPUT. THE SREF SIMILARLY DOWNPLAYS THE SNOW
POTENTIAL...WHICH ALSO MATCHES THE OPERATIONAL ECMWF. ALL OF WHICH
SHOW THAT DESPITE IT BEING COLD ENOUGH ALOFT...SKIN TEMPS OVER THE
SE WILL BE INITIALLY PRETTY WARM IMPLYING THAT EVEN IF SNOW IS THE
PREDOM PRECIP TYPE...MELTING WILL KEEP NUMBERS DOWN.
HIGHS NEAR FREEZING OVER THE NW TODAY WILL ACTUALLY BE VERY CLOSE
TO MID FEB NORMALS...WHILE TEMPS APPROACHING 50 OVER THE SE WILL
BE MORE LIKE 5 TO 10 DEG ABOVE NORMAL.
TIMING OF THE PRECIP LOOKS LIKE THINGS WILL WIND DOWN DURING THE
EVENING WITH LITTLE MORE BUT SOME LINGERING LIGHT SNOW OR FLURRIES
LEFTOVER AFTER MIDNIGHT. LOWS WILL DROP BACK INTO THE TEENS OVER
THE NW...TO NEAR FREEZING OVER THE SE.
&&
.SHORT TERM /SATURDAY/...
AN UPPER TROUGH/LOW WILL CONTINUE THE PROGRESS OF DEEPENING DOWN
INTO THE EASTERN GR LAKES...HELPING DELIVER A LATE WINTER SHOT OF
ARCTIC AIR. IT DOESN`T LOOK LIKE THE COLDEST AIR WE HAVE
EXPERIENCED THIS WINTER...BUT IT WILL CHILL US DOWN BACK BELOW
NORMAL NONE THE LESS.
PRECIP WILL BE ON THE LIGHT SIDE AND MAINLY CONFINED TO THE USUAL
PARTS OF THE STATE FAVORED BY POST FRONTAL LOW LEVEL COLD
ADVECTION SNOW SHOWERS. EXPECT ACCUMULATIONS TO BE LIGHT OVER THE
NW AS LOW LEVEL WINDS WILL INITIALLY NOT ATTAIN A FAVORABLE OVER-
LAKE TRAJECTORY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE UPPER TROUGH IS FCST TO DEEPEN AND CLOSE OFF TO A TIDY UPPER
LOW OVER OR JUST NORTH OF PA DURING THE DAY SUNDAY. THE VARIOUS
OPERATIONAL MODELS USE THIS DEEPENING SYSTEM ALOFT TO DEVELOP
ANOTHER LOW ALONG THE FRONT ALONG OR JUST OFF THE EAST COAST. THE
GFS/ECMWF ACTUALLY SHOW THE PRECIP BRUSHING THE EAST
COAST...POSSIBLY JUST NUDGING INTO MY SERN ZONES A BIT WITH LIGHT
AMOUNTS SUNDAY. THE GEFS LOOKS MORE REASONABLE HOWEVER KEEPING
PRECIP OUT OF MY FCST AREA AND MAINLY OFFSHORE. SO SUNDAY I KEPT
THE FCST DRY EXCEPT FOR THE USUAL WESTERN SNOW SHOWERS.
THE NEXT SYSTEM OF NOTE LOOKS TO ARRIVE ON TUESDAY. AS THE HIGH
SLIDES OFF TO OUR EAST...WE SHOULD SEE WARM AIR FLOOD BACK INTO
THE REGION MAKING FOR MAINLY A RAIN EVENT WITH THE APPROACHING
FRONT. HOWEVER WE WILL HAVE TO WATCH FOR THE POTENTIAL OF A WINTRY
MIX AT THE ONSET IF THE PRECIP ARRIVES EARLY ENOUGH TUESDAY.
IT WILL COOL DOWN ONCE AGAIN BEHIND THE FRONT FOR MID
WEEK...BEFORE MILDER AIR STARTS TO MOVE BACK TOWARD THE REGION
LATE IN THE WEEK. THE PATTERN IS COMPLICATED HOWEVER WITH MODELS
HINTING AT AN UPPER BLOCK DEVELOPING OVER SOUTHERN CANADA. THIS
COULD SUPPRESS THE WARM AIR AND KEEP US JUST COLD ENOUGH THAT ANY
MOISTURE THAT HEADS OUR WAY COULD CREATE THE POTENTIAL FOR SNOW OR
A WINTRY MIX BY WEEK`S END.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
WAVE SLIDING EAST THROUGH VA THIS EVENING IS ALREADY SPREDING
LIGHT PRECIP THROUGH THE UPPER OH VALLEY. THIS PRECIP SHOULD
CREATE LIMITED VISBYS AT JST-AOO-MDT-LNS LATE THIS AFTN AND ALL
EVENING. THE PRECIP AND LOW CLOUDS WILL LIKELY GET CLOSE TO OR
JUST TO THE NORTH OF UNV...BUT NOT UP TO BFD. HOWEVER...WRLY FLOW
AND THE UPPER LEVEL WAVE TO THE NORTH IS CREATING -SHSN OVER NERN
OH AND THESE COULD IMPACT BFD THROUGH THE EVENING AS WELL. WILL
KEEP MENTIONS OF IFR TO THE SRN TIER TERMINALS...AND ONLY FOR
3-6HRS THIS EVENING - BASICALLY WITHIN A FEW HOURS OF 00Z-03Z.
NW FLOW KICKS IN FOR SAT...WITH TYPICAL N/W TERMINALS IN AND OUT
OF MVFR-IFR CONDS THROUGH SUNDAY. IMPROVING CONDITIONS FOR
MONDAY...AS HIGH PRESSURE BUILDS NORTHWARD.
SOME SHOWERS ON TUE...AS NEXT COLD FRONT MOVES TOWARD THE
AREA.
OUTLOOK...
SAT...SHSN/REDUCED VSBYS POSSIBLE W MTNS...ESP LATE.
SUN...BREEZY WITH SHSN POSSIBLE...MAINLY W MTNS.
MON...NO SIG WX EXPECTED.
TUE...SHRASN/REDUCED CIGS POSSIBLE...MAINLY W MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...DANGELO/LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...DANGELO/MARTIN
AREA FORECAST DISCUSSION...UPDATED
NWS BLACKSBURG VA
450 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT CROSSES THE REGION TONIGHT...FOLLOWED BY A STRONGER
ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF LOW
PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE
CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE
ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE
APPALACHIANS LATE MONDAY NIGHT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 445 PM EST FRIDAY...
SENDING A QUICK UPDATE TO PUSH SNOWFALL EAST FASTER BASED ON
CURRENT OBS SHOWING SNOW ALREADY OVER MUCH OF SE WVA. ALSO UPPED
POPS TO REFLECT CURRENT COVERAGE WITH MORE CATEGORICAL FLAVOR OVER
THE WEST EARLY THIS EVENING. LOWERED CURRENT TEMPS WITH READINGS
QUICKLY FALLING FROM THE 40S TO NEAR FREEZING IN AN HOUR OR SO
OVER THE FAR WEST.
AS OF 330 PM EST FRIDAY...
A SHARPENING AND DEEPENING UPPER LEVEL TROF WILL
TAKE SHAPE ACROSS THE EASTERN UNITED STATES BRINING A RETURN TO
WINTER LIKE WEATHER. THE FIRST SHORT WAVE PIVOTS ACROSS THE EASTERN
OHIO VALLEY THEN LIFTS NORTHEAST TONIGHT. THIS PUSHES A COLD FRONT
THROUGH OUR AREA TONIGHT...EXITING THE SOUTHEAST PORTION OF THE
FORECAST AREA BY 02Z.
AS THE BEST LIFT MOVES AWAY FROM OUR AREA...PRECIP CHANCES WILL BE
GREATEST DURING THE EVENING HOURS. BEFORE WE LOSE THE LIFT...STRONG
CAA BEHIND THE SFC FRONT WILL CHANGE THE PRECIP TO SNOW OR A
RAIN/SNOW MIX IN THE MOUNTAINS. ACROSS THE WESTERN SLOPES...CAA AND
A NORTHWEST FLOW WILL SQUEEZE OUT UPSLOPE SNOW SHOWERS WELL INTO THE
NIGHT.
A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS
AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS
UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS
FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP
WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST
AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR
A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP
MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD
LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR
AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE
GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND
A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE
HEAVIEST AMOUNTS OUT OF FORECAST AREA.
STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS
FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS
TO THE EAST AND NO HEADLINES.
AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND
UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST
VIRGINIA.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 408 PM EST FRIDAY...
LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE
MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD
JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT.
DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD
ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST.
ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN
SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME
SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL
DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE
DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE
WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND
6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN
INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET.
WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC
WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS
CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND
GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY
NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A
SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE
DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING
AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER
TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE
GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE
MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF
SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 350 PM EST FRIDAY...
HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT
TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY
STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY
HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL
PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH
HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING
CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING
CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES
ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE
COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE
SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND
PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE
JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE
SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL
CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO
FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER
RIDGES ALONG THE BLUE RIDGE.
HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH
BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED
TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT
PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z
GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION
FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A
PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING
DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT
FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST
SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE
THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO
BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER
AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE
OHIO VALLEY PER THE ECMWF.
TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH
PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY
AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH
A WET COLD AIR DAMMING EVENT EXPECTED.
&&
.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
AS OF 110 PM EST FRIDAY...
COLD FRONT AND ASSOCIATED PCPN POISED TO ENTER THE AREA FROM THE
NW ATTM. RUC AND WRF SEEM TO HAVE SOMEWHAT OF A HANDLE ON THIS SO
WILL USE SHORT TERM EXTRAPOLATION FOR ARRIVAL OF PCPN AND FOLLOW
MESO MODEL GUIDANCE THEREAFTER. BASED ON UPSTREAM CIGS/VSBYS...DO
NOT EXPECT ANYTHING LOWER THAN MVFR WITH THE PCPN. TYPICAL
DOWNSLOPING EAST OF THE BLUE RIDGE SHOULD HELP KEEP THINGS VFR FOR
KROA...KLYH... AND KDAN. WEST OF THE BLUE RIDGE...KLWB AND KBLF
WILL TRANSITION TO AN UPSLOPING PCPN -SHSN EVENT THIS EVENING AND
CONTINUE THROUGH TOMORROW. STILL LOOKING FOR MVFR CIGS/VSBYS AND
EXPECT -SHSN TO BE LIGHT.
KDAN IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT
DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST
WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD. IT CURRENTLY LOOKS LIKE
KDAN WILL BE ON THE EDGE OF THIS AND WILL KEEP SOME BORDERLINE VFR CIGS
IN AFTER 12Z ALONG WITH SOME PCPN.
LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN RESPONSE
TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT WINDS TO HAMPER
AVIATION INTERESTS THROUGH THIS TAF PERIOD.
EXTENDED AVIATION DISCUSSION...
REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS
DISCUSSION:
HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY
SUNDAY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A
NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH
MVFR/IFR CEILINGS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018.
WV...NONE.
&&
$$
SYNOPSIS...AMS/KM
NEAR TERM...AMS/JH/PH
SHORT TERM...KM
LONG TERM...RCS
AVIATION...AMS/NF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
416 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT CROSSES THE REGION TONIGHT...FOLLOWED BY A STRONGER
ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF LOW
PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE
CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE
ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE
APPALACHIANS LATE MONDAY NIGHT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 330 PM EST FRIDAY...
A SHARPENING AND DEEPENING UPPER LEVEL TROF WILL
TAKE SHAPE ACROSS THE EASTERN UNITED STATES BRINING A RETURN TO
WINTER LIKE WEATHER. THE FIRST SHORT WAVE PIVOTS ACROSS THE EASTERN
OHIO VALLEY THEN LIFTS NORTHEAST TONIGHT. THIS PUSHES A COLD FRONT
THROUGH OUR AREA TONIGHT...EXITING THE SOUTHEAST PORTION OF THE
FORECAST AREA BY 02Z.
AS THE BEST LIFT MOVES AWAY FROM OUR AREA...PRECIP CHANCES WILL BE
GREATEST DURING THE EVENING HOURS. BEFORE WE LOSE THE LIFT...STRONG
CAA BEHIND THE SFC FRONT WILL CHANGE THE PRECIP TO SNOW OR A
RAIN/SNOW MIX IN THE MOUNTAINS. ACROSS THE WESTERN SLOPES...CAA AND
A NORTHWEST FLOW WILL SQUEEZE OUT UPSLOPE SNOW SHOWERS WELL INTO THE
NIGHT.
A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS
AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS
UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS
FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP
WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST
AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR
A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP
MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD
LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR
AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE
GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND
A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE
HEAVIEST AMOUNTS OUT OF FORECAST AREA.
STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS
FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS
TO THE EAST AND NO HEADLINES.
AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND
UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST
VIRGINIA.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 408 PM EST FRIDAY...
LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE
MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD
JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT.
DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD
ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST.
ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN
SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME
SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL
DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE
DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE
WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND
6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN
INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET.
WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC
WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS
CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND
GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY
NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A
SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE
DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING
AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER
TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE
GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE
MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF
SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 350 PM EST FRIDAY...
HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT
TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY
STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY
HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL
PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH
HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING
CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING
CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES
ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE
COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE
SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND
PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE
JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE
SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL
CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO
FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER
RIDGES ALONG THE BLUE RIDGE.
HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH
BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED
TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT
PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z
GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION
FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A
PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING
DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT
FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST
SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE
THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO
BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER
AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE
OHIO VALLEY PER THE ECMWF.
TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH
PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY
AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH
A WET COLD AIR DAMMING EVENT EXPECTED.
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AS OF 110 PM EST FRIDAY...
COLD FRONT AND ASSOCIATED PCPN POISED TO ENTER THE AREA FROM THE
NW ATTM. RUC AND WRF SEEM TO HAVE SOMEWHAT OF A HANDLE ON THIS SO
WILL USE SHORT TERM EXTRAPOLATION FOR ARRIVAL OF PCPN AND FOLLOW
MESO MODEL GUIDANCE THEREAFTER. BASED ON UPSTREAM CIGS/VSBYS...DO
NOT EXPECT ANYTHING LOWER THAN MVFR WITH THE PCPN. TYPICAL
DOWNSLOPING EAST OF THE BLUE RIDGE SHOULD HELP KEEP THINGS VFR FOR
KROA...KLYH... AND KDAN. WEST OF THE BLUE RIDGE...KLWB AND KBLF
WILL TRANSITION TO AN UPSLOPING PCPN -SHSN EVENT THIS EVENING AND
CONTINUE THROUGH TOMORROW. STILL LOOKING FOR MVFR CIGS/VSBYS AND
EXPECT -SHSN TO BE LIGHT.
KDAN IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT
DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST
WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD. IT CURRENTLY LOOKS LIKE
KDAN WILL BE ON THE EDGE OF THIS AND WILL KEEP SOME BORDERLINE VFR CIGS
IN AFTER 12Z ALONG WITH SOME PCPN.
LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN RESPONSE
TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT WINDS TO HAMPER
AVIATION INTERESTS THROUGH THIS TAF PERIOD.
EXTENDED AVIATION DISCUSSION...
REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS
DISCUSSION:
HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY
SUNDAY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A
NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH
MVFR/IFR CEILINGS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018.
WV...NONE.
&&
$$
SYNOPSIS...KM
NEAR TERM...AMS/PH
SHORT TERM...KM
LONG TERM...RCS
AVIATION...AMS/NF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
108 PM EST FRI FEB 15 2013
.SYNOPSIS...
A COLD FRONT EXTENDED FROM A LOW OVER THE GREAT LAKES INTO THE
SOUTHERN PLAINS. ANOTHER LOW ALONG THIS FRONT...OVER THE
TENNESSEE VALLEY WILL MOVE EAST ACROSS THE MID ATLANTIC REGION
TODAY THEN OFF THE EAST COAST ON SATURDAY. HIGH PRESSURE WILL
COVER THE EASTERN UNITED STATES SUNDAY AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 100 PM EST FRIDAY...
UPDATED THE FORECAST TO REFLECT THE SLOWER ARRIVAL OF THE INITIAL
SFC FRONT...WHICH EARLY THIS AFTERNOON WAS JUST ENTERING THE FAR
NORTHERN PART OF OUR FORECAST AREA. THIS SLOWER ARRIVAL HAS
ALLOWED TEMPERATURES TO CLIMB MUCH HIGHER THAN MODEL GUIDANCE AND
PREVIOUS FORECASTS. HAVE PUSHED HIGHS TODAY WELL INTO THE 60S EAST
OF THE BLUE RIDGE.
PER THE HIGH RES ARW MODEL...RAIN APPROACHING THE WESTERN PORTION
OF THE FORECAST AREA WILL OVERSPREAD THE MOUNTAINS BETWEEN 21Z-00Z
TONIGHT...ONCE THE FRONT COMES THROUGH AND WINDS BECOME
NORTHWEST...MOUNTAINS WILL GO BACK INTO UPSLOPE SNOW SHOWERS.
EXPECT MUCH OF THE AREA WEST OF A HOT SPRINGS TO BOONE LINE WILL
CHANGE OVER TO SNOW SHOWERS EARLY THIS EVENING. SNOW ACCUMULATIONS
WILL REMAIN VERY LIGHT IN ALL BUT SOUTHEAST WEST VIRGINIA. EVEN IN
THE FAVORED AREAS OF WESTERN GREENBRIER COUNTY NOT EXPECTING
SNOWFALL OF MORE THAN ONE INCH EVERY 12 HOURS. WILL HOLD OFF ON
ANY ADVISORY FOR NOW.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
AS OF 400 AM EST FRIDAY...
WILL START SATURDAY MORNING OFF WITH SNOW SHOWERS ALREADY ONGOING
ACROSS OUR TYPICAL NORTHWEST WIND UPSLOPE AREAS FROM SOUTHEAST WEST
VIRGINIA THROUGH THE NORTH CAROLINA MOUNTAINS. SNOW SHOWER ACTIVITY
WILL BECOME AMPLIFIED FOR A FEW HOURS DURING THE AFTERNOON AS A DEEP
SHORTWAVE ROUNDS THE BASE OF THE LARGER LONG WAVE UPPER LEVEL TROUGH
STRETCHING FROM THE GREAT LAKES THROUGH THE GULF OF MEXICO.
HOWEVER...THIS SHORTWAVE WILL MOVE TO THE EAST QUICKLY...SPREADING
SNOW SHOWER ACTIVITY ACROSS THE VIRGINIA AND NORTH CAROLINA
PIEDMONTS BY EVENING AS A DEEP SURFACE LOW DEVELOPS OFF THE NORTH
CAROLINA COAST.
WITH THE PASSAGE OF THIS SHORTWAVE TROUGH...WE CAN EXPECT THE LARGER
LONGWAVE TROUGH TO GRADUALLY SHIFT EAST THROUGH SATURDAY NIGHT AND
SUNDAY...LEADING TO AN OVERALL DECREASE IN MOUNTAIN SNOW SHOWERS AS
SURFACE HIGH PRESSURE MOVES EAST ALONG THE GULF COAST. SNOW SHOWER
ACTIVITY IS EXPECTED TO END FOR OUR AREA BY SUNDAY AFTERNOON...WITH
CLEARING SKIES AREAWIDE. REGARDLESS...THE UPPER TROUGH WILL STILL BE
CLOSE ENOUGH TO KEEP TEMPERATURES ON THE CHILLY SIDE...RANGING FROM
THE UPPER 20S IN SOUTHEAST WEST VIRGINIA TO THE LOW 40S IN NORTH
CENTRAL NORTH CAROLINA FOR SUNDAY AFTERNOON HIGHS.
HIGH PRESSURE WILL SHIFT EAST SUNDAY NIGHT...ALLOWING WINDS TO
BECOME INCREASINGLY SOUTHERLY. THE SOUTHERLY FLOW WILL ALLOW WARMER
AIR TO BUILD INTO THE AREA...LEADING TO A SIGNIFICANT WARMUP FOR
MONDAY WITH AFTERNOON HIGHS REACHING INTO THE 40S AND LOW 50S. WIND
SPEEDS WILL INCREASE ACROSS THE MOUNTAINS MONDAY NIGHT AS ANOTHER
STRONG COLD FRONT APPROACHES THE AREA...AND MAY SEE ANOTHER ROUND OF
STRONG GUSTS DEVELOP ACROSS THE MOUNTAIN EMPIRE THROUGH THE NORTH
CAROLINA MOUNTAINS DURING THE OVERNIGHT HOURS. AS THE COLD FRONT
NEARS MONDAY NIGHT...SHOWER ACTIVITY WILL BEGIN TO ENTER THE AREA.
DESPITE THE WARMER AIR BUILDING ALOFT...BELIEVE SURFACE TEMPERATURES
WILL TAKE LONGER TO REBOUND...LEADING TO RAIN SHOWERS MIXED WITH
SLEET OR SNOW AT TIMES FOR THE MOUNTAINS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 400 AM EST FRIDAY...
A COLD FRONT WILL SWING ACROSS THE REGION TUESDAY...WITH A MIX OF
RAIN AND WINTRY PRECIPITATION CONTINUING ACROSS THE MOUNTAINS FOR
TUESDAY MORNING...THEN SHOWERS FOR THE ENTIRE AREA TUESDAY
AFTERNOON. THE FRONT MAY GET STUCK ALONG THE EAST COAST TUESDAY
NIGHT AS A LOW PRESSURE SYSTEM DEVELOPS ACROSS THE SOUTHEASTERN USA.
THIS FRONT WILL THEN JOG OUT TO SEA ON WEDNESDAY WITH A CHILLY HIGH
PRESSURE SYSTEM SETTLING OVER THE REGION THROUGH THURSDAY. POCKETS
OF FREEZING RAIN MAY AGAIN DEVELOP IN SOME MOUNTAIN VALLEYS FRIDAY
MORNING AS THE NEXT FRONTAL SYSTEM SWINGS ACROSS THE REGION.
TEMPERATURES WILL RUN ABOVE NORMAL MONDAY AND TUESDAY. TEMPERATURES
WILL DIP BELOW NORMAL ON WEDNESDAY...THEN REBOUND TOWARD NORMAL ON
THURSDAY.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 110 PM EST FRIDAY...
COLD FRONT AND ASSOCIATED PCPN POISED TO ENTER THE AREA FROM THE
NW ATTM. RUC AND WRF SEEM TO HAVE SOMEWHAT OF A HANDLE ON THIS SO
WILL USE SHORT TERM EXTRAPOLATION FOR ARRIVAL OF PCPN AND FOLLOW
MESO MODEL GUIDANCE THEREAFTER. BASED ON UPSTREAM CIGS/VSBYS...DO
NOT EXPECT ANYTHING LOWER THAN MVFR WITH THE PCPN. TYPICAL
DOWNSLOPING EAST OF THE BLUE RIDGE SHOULD HELP KEEP THINGS VFR FOR
KROA...KLYH... AND KDAN. WEST OF THE BLUE RIDGE...KLWB AND KBLF
WILL TRANSITION TO AN UPSLOPING PCPN -SHSN EVENT THIS EVENING AND
CONTINUE THROUGH TOMORROW. STILL LOOKING FOR MVFR CIGS/VSBYS AND
EXPECT -SHSN TO BE LIGHT.
KDAN IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT
DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST
WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD. IT CURRENTLY LOOKS LIKE
KDAN WILL BE ON THE EDGE OF THIS AND WILL KEEP SOME BORDERLINE VFR CIGS
IN AFTER 12Z ALONG WITH SOME PCPN.
LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN RESPONSE
TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT WINDS TO HAMPER
AVIATION INTERESTS THROUGH THIS TAF PERIOD.
...EXTENDED AVIATION DISCUSSION...
REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS
DISCUSSION:
HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY
SUNDAY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A
NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH
MVFR/IFR CEILINGS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/PH
SHORT TERM...NF
LONG TERM...NF/RCS
AVIATION...AMS/NF
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
319 PM CST FRI FEB 15 2013
.SHORT TERM...THROUGH MONDAY NIGHT
319 PM CST FRI FEB 15 2013
BENIGN WEATHER THROUGH THE WEEKEND LEADS INTO MONDAYS WEATHER
SYSTEM WHICH WILL NEED TO BE WATCHED FOR CHANGES.
MUCH LESS CLOUD ACROSS THE AREA TODAY THAN FORECAST WITH MIXING
NOT DEEP ENOUGH TO FORM MUCH STRATOCUMULUS EXCEPT OVER
NORTHCENTRAL WI. LONGWAVE TROUGH AXIS CONTINUES EASTWARD PROGRESS
WITH LAST OF SHORTWAVE TROUGH ENERGY COMING THROUGH TONIGHT AND
EARLY SATURDAY. LATEST RAP AND WATER VAPOR HAS THIS BROAD
CIRCULATION AXIS FROM KINL-KLBF...AND SURFACE LOW PRESSURE IN
EASTERN NEB. CLOUD COVER OVER NWRN MN MOVING TOWARD THE AREA WILL
ARRIVE THIS EVENING FOR A CLOUD PERIOD INTO SATURDAY MORNING. NOT
TO CONFIDENT ON THE COVERAGE OF THIS CLOUD COMING IN...IT MAY BE
MORE IN AREAS. HAVE LEFT A MENTION OF FLURRIES IN THIS WEAKLY
LIFTED AIR MASS THROUGH NOON SATURDAY.
AGGRESSIVE RIDGE BUILDING THEN TAKES PLACE LATER SATURDAY AND
SUNDAY. UPSTREAM RAOB HEIGHT RISES SEEN ACROSS WRN CANADA WITH
THIS PROGRESSIVE HIGHER AMPLITUDE RIDGE. HAVE COOLED THE LOW
TEMPERATURES SUNDAY MORNING OVER CENTRAL WI WITH NEARLY CALM WINDS
AND LITTLE CLOUD UNDER LOW-LEVEL RIDGING. THESE ARE BELOW MOS
GUIDANCE BY ABOUT 5-7F. WARM ADVECTION WILL BEGIN TO RAISE
TEMPERATURES SUNDAY AND THE FORCING DOES NOT SEEM SUFFICIENT TO
CREATE PRECIPITATION PER CONSENSUS 15.12Z MODEL GUIDANCE.
HOWEVER...THE WARM ADVECTION AND THERMAL RIBBON LIFTING ACROSS THE
AREA WILL CREATE AN ARC OF CLOUDS ORIENTED NW-SE TO SHIFT NEWRD
ACROSS THE AREA. HAVE INCREASED SKY COVER A BIT FOR SUNDAY...SOME
FLURRIES MAY BE POSSIBLE BUT HAVE NOT INCLUDED THEM IN THE
FORECAST.
FAIRLY INTERESTING TROUGH TO SHIFT INTO THE AREA MONDAY. THE
TROUGH IS CURRENTLY IN THE ERN PACIFIC APPROACHING 47N/140W PER
GOES WATER VAPOR. MODEL GUIDANCE CONSENSUS FROM 15.12Z IS THAT
THERE WILL NRN AND SRN ENERGY IN THIS TROUGH. THE SRN PIECE OF
ENERGY IS HANDLED DIFFERENTLY BY THE LATEST GUIDANCE. THE 15.12Z
NAM/SREF DEVELOP ONLY A WEAK CYCLONE VIA THE SRN ENERGY...WHILE THE
GEM GLOBAL AND 15.00Z FIM MODEL ARE AGGRESSIVE WITH THE CYCLONE
DEEPENING IT ALONG A KANSAS CITY TO MILWAUKEE TRACK...AND DROPPING
A 4-8 INCH SNOW BAND ACROSS WI. 15.12Z ECMWF/GFS ARE SIMILAR AND
OFFER A COMPROMISE BETWEEN THE TWO CAMPS WITH THE CYCLONE
DEEPENING LATER...INTO MICHIGAN. HAVE GONE WITH THIS COMPROMISE ON
TIMING AND INTENSITY.
MONDAY WILL SEE A GULF SURGE OF MOISTURE IN THE SOUTHERLY FLOW...
DEEPENING A SURFACE-BASED LAYER TO OVER 1 KM DEEP. THIS WILL BE
PRE-FRONTAL IN THE SOUTHERLY FLOW AND WITHOUT DEEP CLOUD AND
ICE...BUT ISENTROPIC LIFT OF 3-5 UB/S IN THE LAYER ...DZ/FZDZ
WILL BE POSSIBLE. THE MOIST TONGUE IS MAINLY IN WI AND EAST AND
THAT IS WHERE DZ/FZDZ CHANCES WILL BE BEST. TEMPERATURES WILL BE
WARMING MONDAY WITH ABOVE FREEZING HIGHS AROUND I-90 AND SOUTH
EXPECTED. THUS...DZ OR RAIN SHOWERS COULD BE FREEZING IN THE EARLY
AFTERNOON IF ROADS DO NOT RESPOND TO WARMING. WITH QPFS LESS THAN
0.10 INCHES...WOULD EXPECT ONLY LIGHT ICING TO OCCUR. AS TROUGH
SHIFTS EAST LATE MONDAY AND MONDAY EVENING...A TRANSITION TO SNOW
WILL OCCUR FROM WEST TO EAST WITH SNOW AMOUNTS OF LESS THAN AN
INCH. HAVE INCREASED PRECIPITATION CHANCES OVERALL...BUT WI LOOKS
TO BE THE MAIN WEATHER AREA FOR THIS SYSTEM. THERE IS A CHANCE
THIS COULD NEED AN ADVISORY IF FREEZING PRECIPITATION LOOKS MORE
WIDESPREAD OR THE MORE AGGRESSIVE CYCLONE SOLUTION IN THE GEM
SHOULD BECOME MORE PROBABLE. THE SPREAD IN THE CYCLOGENESIS SEEN
FROM THE SRN ENERGY IN THE MODEL GUIDANCE SUGGESTS THIS IS AN
UNSTABLE SYSTEM AND COULD LEAD TO FORECAST CHANGES. WILL TAKE A
STEP UP IN OUR FORECAST VISIBILITY OF THIS SYSTEM.
.LONG TERM...TUESDAY THROUGH FRIDAY
319 PM CST FRI FEB 15 2013
ACTIVE EXTENDED PERIOD SETTING UP WITH THE FOCUS ON A SHORT ARCTIC
INTRUSION MID WEEK FOLLOWED BY THE POTENTIAL OF A WINTER STORM TO
IMPACT THE UPPER MIDWEST NEXT THURSDAY NIGHT AND FRIDAY.
GOING INTO TUESDAY...A LOT DEPENDS ON THE EVOLUTION AND PHASING OF
THE STORM SYSTEM THAT IS EXPECTED TO TRACK THROUGH MONDAY AND MONDAY
NIGHT...AND HOW MUCH ARCTIC AIR IS PULLED SOUTH IN ITS WAKE. 15.12Z
GUIDANCE SHOWS SIMILAR SOLUTIONS FOR 850 MB TEMPERATURES TO PLUMMET
AS LOW AS -15C TO -20C TUESDAY AND WEDNESDAY. STANDARDIZED
ANOMALIES FOR THIS PERIOD RANGE FROM 1 TO 1.5 BELOW NORMAL AND WITH
BROAD CYCLONIC FLOW ALOFT...IT WILL MAKE FOR A COUPLE COLD WINTER
DAYS. HIGHS IN THE TEENS AND OVERNIGHT LOWS IN THE SINGLE DIGITS
ABOVE ZERO...WITH OCCASIONAL LIGHT SNOW OR FLURRIES TUESDAY.
THE COLD AIRMASS SETS THE STAGE FOR LATER IN THE WEEK AS A WESTERN
CONUS TROUGH DEEPENS AND MOVES EAST. AS HAS BEEN ALLUDED TO IN
PREVIOUS DISCUSSIONS...THE RUN-TO-RUN AND MODEL CONSISTENCY FOR
THIS FEATURE REMAINS VERY HIGH. DETERMINISTIC MODELS STILL POINT
FOR A SURFACE LOW TRACK THROUGH THE CENTRAL PLAINS TO NORTHERN
ILLINOIS BY 12Z FRIDAY BRINGING WIDESPREAD PRECIPITATION TO THE
ENTIRE AREA WITH A CLASSIC DEFORMATION BAND OF SNOW SETTING UP.
LOOKING AT THE 15.12Z GFS ENSEMBLE...SURFACE LOW TRACK LOCATIONS
VARY FROM EASTERN IOWA...SOUTHERN WISCONSIN...AND ILLINOIS.
SIMILAR IDEAS ARE FOUND IN THE 15.00Z ECMWF ENSEMBLE. THE
STABILITY AND LACK OF SPREAD WITHIN THE NUMERICAL GUIDANCE FOR
THIS WEATHER SYSTEM ARE VERY HIGH.
ONE ISSUE THAT MAY PRECLUDE THIS FROM BEING A MORE SIGNIFICANT EVENT
IS THAT THE BOTH THE UPPER LEVEL AND SURFACE WAVES APPEAR TO BE
WEAKENING AS IT APPROACHES THE UPPER MIDWEST. 500 MB STANDARDIZED
ANOMALIES DROP FROM -2.5 ACROSS KANSAS TO BARELY BELOW NORMAL AS IT
CROSSES THE AREA. THIS IS REFLECTED IN THE SURFACE LOW PRESSURE
WHICH REMAINS AROUND 1000 MB THROUGHOUT. EARLIER RUNS SHOWED DEEPER
CYCLOGENESIS WITH 980-990 MB LOWS. THE 15.12Z ECMWF REALLY DAMPENS
OUT THE UPPER LEVEL AND SURFACE WAVE...BECOMING ALMOST OCCLUDED BY
FRIDAY AFTERNOON.
TEMPERATURE PROFILES ACROSS THE AREA CONTINUE TO SHOW AN ALL SNOW
EVENT...THOUGH THERE IS A SLIGHT WARMING TREND NOTED. IF THE
SYSTEM WERE TO DEEPEN AND WRAP UP MORE...THEN A PUSH OF WARMER AIR
COULD PRESENT A RAIN/SNOW MIX BUT RIGHT NOW THIS IS NOT THE CASE.
HAVE TRENDED PRECIPITATION CHANCES ABOVE MODEL CONSENSUS THURSDAY
NIGHT GIVEN CONTINUED EXCELLENT MODEL AGREEMENT AND THE SLOWER
TIMING OF THE SYSTEM.
ALTHOUGH IT IS A BIT TOO EARLY TO SPECULATE ON AMOUNTS...25.12Z GFS
ENSEMBLE AND 25.12Z ECMWF SHOW WIDESPREAD AMOUNTS OF 0.50 TO 0.75
INCHES OF LIQUID. SNOW RATIOS ARE NOT VERY HIGH...MOST LIKELY A BIT
BELOW CLIMATOLOGICAL VALUES /10 TO 12:1/ SO IN SHORT...WARNING
LEVEL /6 INCHES/ SNOW TOTALS COULD BE MET OR EXCEEDED ACROSS PARTS
OF THE AREA.
&&
.AVIATION...THROUGH 18Z SATURDAY
1148 AM CST FRI FEB 15 2013
LOW CONFIDENCE FORECAST ON CLOUD TRENDS TODAY INTO TOMORROW AS THE
REGION REMAINS IN NORTHWESTERLY FLOW. MAINLY JUST HIGH LEVEL CLOUD
COVER TO CURRENTLY CONTEND WITH BUT SOME OF THE SHORT TERM
GUIDANCE...SUCH AS THE 15.15Z HRRR...STILL WANT TO DEVELOP A LOW
LEVEL CUMULUS FIELD EARLY THIS AFTERNOON AND KEEP IT GOING INTO
THE EVENING. A MORE WIDESPREAD STRATUS DECK PERCHED IN NORTHWEST
MINNESOTA LOOKS LIKE IT WILL MOVE IN THIS EVENING AND SHOULD
PERSIST INTO TOMORROW MORNING. SINCE THERE IS LITTLE ON SATELLITE
AT THE MOMENT SHOWING THE CU DEVELOPING...HAVE SCALED BACK ON THE
MVFR CEILINGS FORMING THIS AFTERNOON AND PUSHED IT BACK TO WHEN
THE MORE WIDESPREAD STRATUS MOVES IN TONIGHT. WITH ANY LOW LEVEL
CLOUDS THAT DO FORM...SNOW SHOWERS AND FLURRIES WILL BE POSSIBLE
THAT COULD BRING VISIBILITY BRIEFLY DOWN TO 1-3SM AT TIMES. WINDS
WILL REMAIN OUT OF THE NORTHWEST AT 7-15KTS THROUGHOUT THE PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
319 PM CST FRI FEB 15 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...TAYLOR/BAUMGARDT
AVIATION...HALBACH