Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/08/13
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
921 PM PST SAT JAN 5 2013
.SHORT TERM DISCUSSION...
SATELLITE IMAGERY SHOWED A ELONGATED SPLITTING TROUGH ALIGNED ALONG
THE PACIFIC COASTLINE FROM THE GULF OF ALASKA TO SAN FRANCISCO EARLIER
THIS EVENING. LATEST WATER VAPOR LOOP SHOWS THAT ENERGY ROUNDING THE
BASE OF THIS TROUGH HAS BEGUN TO DECOUPLE FROM THE MEAN WESTERLY JET
AND IS SHOWING SIGNS THAT IT IS FORMING A 550MB CLOSED LOW LESS THAN
A HUNDRED MILES OFFSHORE OF THE BAY AREA.
THE BROAD TRANSITIONAL NATURE OF THIS SYSTEM LEAD TO RELATIVELY
WEAK DIFFERENTIAL FORCING/ISENTROPIC LIFT THUS FAR. THE RESULT OF
THIS IS A WIDESPREAD ALBEIT LIGHT PRECIPITATION EVENT. THIS IS
EVIDENT BY AREAL RAIN GAGES REPORTING LESS THAN A TENTH OF RAIN
WITH ONLY A SELECT FEW BREACHING THE QUARTER INCH MARK THIS
EVENING. RADAR IMAGERY SHOWS WIDESPREAD LOW REFLECTIVITIES
INDICATIVE OF LIGHT PRECIPITATION WITH THE EXCEPTION OF AN AREA OF
HEAVIER RAIN/GRAUPEL ON THE WESTERN PERIPHERY OF THE CENTRAL SAC
VALLEY. KRDD STRUGGLING TO SECURE A TRACE OF RAIN SO FAR.
THE UPPER LEVEL SYSTEMS ARRIVAL HAS HASTENED SINCE THE LAST SHORT
TERM MODELS WERE INITIALIZED. THE SREF...NAM...AND HRRR MODELS ARE
ALL LAGGING REALITY BY ABOUT 3 HOURS PER LATEST RADAR IMAGERY.
DESPITE THIS... WOULD AGREE WITH THE SHORT TERM MODELS SCALING
BACK PRECIP OVER THE NORTHERN SAC VALLEY/SOUTHERN CASCADES TONIGHT
AND TOMORROW MORNING. DECIDED TO SCALE BACK PRECIP
COVERAGE AND PROBABILITY OVER THE NEXT 72 HRS AND SENT OUT A
FORECAST UPDATE.
SNOW LEVELS OVER THE COASTAL RANGE ARE DROPPING AS A RESULT OF
COLD POST FROPA AIR MOVING INTO THE REGION. INITIALLY ABOVE
4500FT... WEBCAMS HAVE SHOWN THE SNOW LEVEL TO BE BETWEEN 2500FT
AND 3000FT IN LAKE COUNTY. EXPECT A FURTHER DROP OVERNIGHT.
REMAINDER OF AFTERNOON FORECAST PACKAGE ON TRACK.
.PREVIOUS DISCUSSION...
UPPER LOW APPROACHING THE WEST COAST WILL DISPLACE THE HIGH THAT
HAS BEEN OVER THE AREA THE PAST FEW DAYS. ENERGY DROPPING THROUGH
THE TROUGH WILL CAUSE AN UPPER LOW TO SPLIT FROM THE TROUGH NEAR
THE BAY AREA TONIGHT. RAIN WILL SPREAD INTO THE VALLEY THIS
EVENING...AFTER 6 PM FOR MOST AREAS. SNOW LEVELS WILL START OUT
NEAR 5000 FEET OVER THE SIERRA AND 3000 FEET FOR THE COASTAL RANGE
AND SHASTA COUNTY. LEVELS WILL FALL TO 4000 FEET FOR THE SIERRA
AND 2500 FEET FARTHER NORTH SUNDAY MORNING. SNOWFALL WILL BE LIGHT
WITH THIS SYSTEM...AS THE BEST MOISTURE AND DYNAMICS WILL BE OVER
THE SOUTHERN SIERRA AND SOCAL. EXPECT 2 TO 4 INCHES OVER THE
COASTAL RANGE AND SIERRA DURING THE NEXT 24 HRS. HAVE RAISED
OVERNIGHT POPS AND ALSO ADJUSTED FOR EARLIER TIMING...AS SYSTEM IS
A FEW HOURS AHEAD OF SCHEDULE. THIS LINES UP NICELY WITH RUC/HRRR
WHICH BEGIN PRECIP OVER THE COASTAL RANGE AROUND 4 PM AND SAC/SAN
JOAQUIN VALLEY AROUND 6 PM. PRECIP WILL BE SLOWER TO SPREAD INTO
THE SIERRA WHERE A DRIER ATMOSPHERE EXIST...ACCUMULATING SNOW
THERE WILL NOT START UNTIL AFTER MIDNIGHT.
UPPER LOW WILL DROP SOUTH OVER SOCAL ON SUNDAY. PRECIP WILL
DIMINISH FROM NORTHWEST TO SOUTHEAST DURING THE DAY.
ALTHOUGH...STILL REMAIN IN THE LIKELY CATEGORY OVER THE SIERRA
SOUTH OF I-80. FOG COULD BE A CONCERN SUNDAY NIGHT IF SKIES
CLEAR...BUT AT THIS TIME WILL KEEP THE CLOUDS OVER THE AREA.
DISTURBANCE AND MOISTURE PLUME OVER WASHINGTON AND OREGON ON
MONDAY WILL BRUSH NORTHERN AREAS AND WILL KEEP SHOWER CHANCES
GOING FOR SHASTA COUNTY AND THE COASTAL RANGE. HEIGHT RISES AHEAD
OF THIS SYSTEM WILL LEAD TO WARMER TEMPERATURES WITH HIGHS
GENERALLY FROM 55 TO 60. RIDGE WILL STRENGTHEN OVER NORCAL ON
TUESDAY PUSHING SHOWER CHANCES NORTH OF THE AREA. TEMPERATURES
WILL BE FROM THE MID 50`S TO LOWERS 60`S FOR VALLEYS.
.EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY)
SLIGHT CHANCE TO CHANCE OF PRECIP ACROSS NORCAL WED & THURS AS A
TROUGH OVER THE PAC NW DEEPENS INTO OUR REGION. SNOW LEVELS COULD
LOWER INTO THE FOOTHILLS ALTHOUGH MODELS INDICATE THAT ANY
SNOWFALL WOULD BE LIGHT AT THE LOWER ELEVATIONS. THE TROUGH AXIS
MOVES INTO THE GREAT BASIN REGION BY FRIDAY AND BREEZY NORTH TO
NORTHEAST FLOW WILL DEVELOP IN OUR CWA BEHIND THE TROUGH. FRIDAY
AND SATURDAY WILL BE DRIER WITH THE NORTHERLY FLOW BUT SOME LIGHT
SHOWERS MAY STILL AFFECT THE NORTHERN MOUNTAINS AND SHASTA COUNTY.
OVERNIGHT LOWS WILL BE BELOW NORMAL WITH DAYTIME HIGHS AT OR
SLIGHTLY BELOW NORMAL. IT SHOULD BE NOTED THAT THE ECMWF MODEL IS
A BIT OF AN OUTLIER IN THE EXTENDED AS IT DIFFERS FROM THE GEM &
GFS (THE PATTERN MENTIONED ABOVE) IN TRACK AND TIMING. JBB
&&
.AVIATION...
VFR/MVFR CONDITIONS AND AREAS OF IFR/LIFR CONDITIONS IN THE VALLEY WITH
AN UPPER LEVEL LOW MOVING INTO THE AREA TONIGHT BRINGING SHOWERS.
IFR/LIFR CONDITIONS EXPECTED IN THE MOUNTAINS OVERNIGHT INTO SUNDAY
WITH SNOW LEVELS AROUND 3000 TO 4000 FT. SWLY WIND GUSTS UP TO 40
KTS NEAR SIERRA RIDGES. PRECIPITATION EXPECTED TO DIMINISH FROM
NORTH TO SOUTH SUNDAY AFTERNOON AND EVENING.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1004 PM MST SAT JAN 5 2013
.AVIATION...
VFR CONDITIONS ARE EXPECTED TO CONTINUE OVER THE KCOS AND KPUB TAF
SITES THROUGH SUNDAY. AT ALS...THE POTENTIAL FOR LIFR CONDITIONS IS
STILL ANTICIPATED AT TIMES LATER TONIGHT DUE TO CIGS AND VIS
ASSOCIATED WITH FZFG...THEN VFR CONDITIONS SHOULD RETURN TO
KALS...ESPECIALLY AFT 16Z SUNDAY.
&&
.PREV DISCUSSION... /ISSUED 249 PM MST SAT JAN 5 2013/
SHORT TERM...
(TONIGHT AND SUNDAY)
SHORTWAVE PASSING OFF TO THE NORTHEAST HAS SENT A DRY COLD FRONT
THROUGH THE SE PLAINS. WINDS NOT TERRIBLY STRONG WITH IT...AND
MIXING HAS ACTUALLY WARMED TEMPS A FEW DEGREES IN SPITE OF THE CAA
BEHIND THE FRONT...WITH KLAA AT 45 DEGREES SO FAR...COMPARED TO
YESTERDAY`S HIGH OF ONLY 39. MEANWHILE...THE SAN LUIS VALLEY HAS
BEEN STRUGGLING TO WARM...WITH KALS ONLY AT 11 DEGREES AS OF 21Z.
TONIGHT...CLEAR SKIES...DRY SFC DEW POINTS...AND SNOW COVER IN SOME
PLACES WILL LEAD TO ANOTHER COLD NIGHT. CAN`T FIND A REASON WHY
KALS WON`T DROP TO AROUND -30 AGAIN TONIGHT...SO TOOK MIN TEMPS
THERE WELL BELOW GUIDANCE. OTHER CHALLENGE WILL BE POTENTIAL FOR
FOG IN THE SAN LUIS VALLEY. THIS DIDN`T HAPPEN LAST NIGHT...OR AT
LEAST VISIBILITY AT KALS DIDN`T DROP BELOW 5 MILES...THOUGH WE DID
SEE SOME LIFR STRATUS IN THE WEB CAMS AND IN THE CEILOMETER DATA FROM
ASOS. NAM12 SOUNDINGS SATURATE AT THE SFC AROUND 02Z AND REMAIN SO
THROUGH 15Z SUN. THE LOCAL 4 KM WRF ALSO INDICATES POTENTIAL FOR
FOG...AND HRRR SHOWS SFC RHS APPROACHING 80% BY 09Z SUN. RAP
SOUNDINGS BY CONTRAST LOOK FAIRLY DRY...AND NEITHER THE MET NOR MAV
GUIDANCE HAVE ANY INDICATION OF FOG. WILL THROW PATCHY FOG INTO THE
GRIDS FOR NOW...BUT WILL DELAY THIS UNTIL AFTER 06Z. HUNCH IS IT
WON`T OCCUR UNTIL AFTER 09-10Z BASED ON WHAT HAPPENED LAST
NIGHT...AND SHOULD BREAK BY 15-16Z ON SUN.
FLOW ALOFT BECOMES MORE SOUTHWESTERLY ON SUNDAY AS THE UPPER RIDGE
SHIFTS EASTWARD AND NEXT UPPER LOW MOVES INTO CA. LEE TROF
DEEPENS IN RESPONSE WITH WINDS AIDING IN BETTER MIXING ALONG THE
I-25 CORRIDOR. CURRENT FORECAST WITH 40S AND LOWER 50S LOOK
REASONABLE ACROSS THE PLAINS. MEANWHILE...DRY CONDITIONS WILL
CONTINUE EVERYWHERE. ITS POSSIBLE THAT KALS COULD SEE SOME
MODERATING TEMPERATURES AS WELL IF WINDS CAN MIX IN...BUT GIVEN THE
STRONG INVERSIONS...KEPT TEMPS BELOW GUIDANCE VALUES WITH SOME MINOR
IMPROVEMENT. -KT
LONG TERM...
(SUNDAY NIGHT-SATURDAY)
SUNDAY NIGHT-MONDAY...LATEST MODELS CONTINUE TO BE IN GOOD AGREEMENT
OF DEVELOPING SPLIT FLOW PATTERN INTO THE MIDDLE WEEK. CLOSED LOW IN
THE DEVELOPING SOUTHERN STREAM ACROSS THE SOUTHEASTERN NEVADA SUNDAY
AFTERNOON PROGGED TO DIVE INTO OLD MEXICO THROUGH THE DAY MONDAY AS
A MINOR WAVE EMBEDDED IN THE ZONAL FLOW ACROSS NORTHERN TIER OF
STATES TRANSLATES ACROSS THE NORTHERN ROCKIES AND INTO THE NORTHERN
HIGH PLAINS. OVERNIGHT LOWS...ESPECIALLY IN THE SAN LUIS VALLEY
REMAIN TRICKY WITH SOME INCREASE IN HIGH LEVEL MOISTURE SPREADING
ACROSS THE REGION...THOUGH DOES NOT LOOK TO BE ENOUGH TO KEEP TEMPS
FROM TANKING...AND HAVE GONE BELOW GUIDANCE VALUES IN THE HIGH MT
VALLEYS. BOTH SYSTEMS REMAIN TOO FAR AWAY FROM THE AREA TO PRODUCE
ANY PRECIPITATION...THOUGH WILL SEE SLIGHTLY COOLER TEMPERATURES
AS PASSING NORTHERN STREAM SYSTEM SENDS A WEAK BACKDOOR COLD FRONT
ACROSS EASTERN COLORADO MONDAY MORNING.
MONDAY NIGHT-WEDNESDAY NIGHT...WEAK FLOW PROGGED ACROSS THE AREA
THROUGH THIS PERIOD AS OLD MEXICO LOW SLOWLY LIFTS OUT INTO THE
SOUTHERN HIGH PLAINS. MODELS DIFFER ON TRACK WITH THE EC A TAD
FURTHER NORTH AND WEST WITH SAID SYSTEM ACROSS THE NORTH CENTRAL
TEXAS PANHANDLE WEDNESDAY NIGHT AND PRINTS OUT SOME LIGHT QPF
ACROSS THE FAR SE PLAINS. WITH THE WEAK FLOW ALOFT...HAVE GONE BELOW
GUIDANCE FOR HIGHS THROUGH THE PERIOD...WITH TEMPERATURES MAINLY IN
THE 40S TO LOWER 50S ACROSS THE PLAINS AND 30S ACROSS THE HIGHER
TERRAIN. AGAIN...HAVE STAYED WELL BELOW GUIDANCE FOR THE SAN LUIS
VALLEY AS NOT ENOUGH WIND TO SCOUR OUT THE COLD AIRMASS IN PLACE.
THURSDAY-SATURDAY...LATEST MODELS CONTINUE TO INDICATE A BETTER
CHANCE OF WIDESPREAD PRECIPITATION INTO THE EARLY WEEKEND AS PACIFIC
ENERGY DIGGING INTO THE GREAT BASIN ON THURSDAY SLOWLY LIFTS OUT
ACROSS THE ROCKIES THROUGH SATURDAY. SOME CONCERN THAT STRONG
BACKSIDE JET ACROSS THE GREAT BASIN COULD DIG THE SYSTEM FURTHER
SOUTH THAN CURRENT PROJECTIONS...SO HAVE KEPT CURRENT MODEL
CONSENSUS SOLUTION WHICH GIVES CHANCE POPS ACROSS THE CONTINENTAL
DIVIDE THURSDAY NIGHT AND FRIDAY...WITH CHANCE AND SLIGHT CHANCE
POPS SPREADING ACROSS THE REST OF THE HIGHER TERRAIN THROUGH THE
EASTERN PLAINS FRIDAY THROUGH SATURDAY. TEMPERATURES WILL ALSO BE
TRENDING BACK BELOW SEASONAL AVERAGES BY FRIDAY AND SATURDAY. -MW
AVIATION...
CLEAR SKIES AND VFR CONDITIONS EXPECTED AT KPUB AND KCOS THROUGH
SUNDAY. CHALLENGE WILL BE THE POTENTIAL FOR LIFR CIGS AND POSSIBLY
VIS IN FZFG AT KALS OVERNIGHT. MODELS DIFFER IN WHETHER THIS WILL
OR WILL NOT OCCUR...AND CONFIDENCE IS LOW. PLAN TO DELAY LIFR
CONDITIONS UNTIL AFTER 09Z IN NEXT TAF ISSUANCE. ANY LIFR CIGS/VIS
SHOULD BREAK BETWEEN 15-16Z...WITH VFR CONDITIONS AND LIGHT WINDS
THROUGH SUNDAY. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS ALBANY NY
1230 AM EST SUN JAN 6 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION THIS EVENING...WILL SLIDE OFF THE
ATLANTIC SEABOARD LATER TONIGHT. LOW PRESSURE AND ITS ASSOCIATED
COLD FRONT TRACKING EAST FROM THE GREAT LAKES WILL MOVE THROUGH OUR
REGION LATE TONIGHT THROUGH SUNDAY NIGHT. THIS COULD BRING PERIODS
OF LIGHT SNOW OR SNOW SHOWERS...WITH THE BEST CHANCE FOR
ACCUMULATIONS IN THE HIGHER TERRAIN. DRIER AND MILDER WEATHER IS
EXPECTED THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
AS OF MIDNIGHT...REGIONAL RADAR RETURNS REVEAL AN INCREASING TREND
OF PRECIPITATION EVOLVING AS WEAK WARM ADVECTION AND ISENTROPIC LIFT
IS UNDERWAY. HRRR EXPERIMENTAL REFLECTIVITIES SUGGEST THIS BAND OF
LIGHT SNOW/-SHSN WILL OVERSPREAD THE ENTIRE REGION BY 09Z AND HAVE
INCREASED POPS TO 30% FOR THE OVERNIGHT PERIOD. THERE IS A NOTABLE
DRY SLOT UPSTREAM OVER THE OHIO VALLEY THAT WILL ADVANCE NORTHEAST
TOWARD SUNRISE. THIS SHOULD REDUCE COVERAGE OF PRECIP THROUGH MOST
OF THE DAYLIGHT HOURS ON SUNDAY WITH PERHAPS FLURRIES FOR MOST
LOCATIONS. THE LAKE ONTARIO CONTRIBUTION DOES NOT APPEAR TO BE
OCCURRING ON SUNDAY AS PREVIOUSLY THOUGHT AND MAY HAVE TO REDUCE
ACCUMULATIONS WITH THE NEXT UPDATE. AS FOR TEMPERATURES...WE HAVE
NOW STEADY THOSE VALUES WITH A SLOWLY RISE EXPECTED THE REMAINDER OF
THE OVERNIGHT PERIOD WHICH WILL CONTINUE INTO SUNDAY AFTERNOON.
COLD FRONT AND UPPER TROUGH IS STILL SCHEDULED TO MOVE ACROSS THE
REGION TONIGHT...WITH TRENDS TOWARD A FASTER AND A SOMEWHAT DRIER
SOLUTION. NOT SO DOWNWIND OF LAKE ONTARIO WHERE SOME LAKE
CONTRIBUTION COULD ALLOW FOR A BETTER CONCENTRATION FOR SNOW. MORE
ON THIS WITH THE NEXT UPDATE.
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
THE CLIPPER SYSTEM WILL PASS ACROSS FAR NORTHERN NEW YORK AND
NORTHERN NEW ENGLAND SUNDAY INTO SUNDAY NIGHT. AS IS USUALLY THE
CASE WITH THESE CLIPPER SYSTEMS...EXPECT MOST OF THE SIGNIFICANT
SNOWFALL ASSOCIATED WITH IT TO REMAIN ALONG OR TO THE NORTH OF THE
SURFACE LOW TRACK. THIS WILL RESULT IN VERY LITTLE PCPN FOR MOST OF
THE ALBANY FORECAST AREA WITH THE EXCEPTION OF THE ADIRONDACK
ZONES. FOR MUCH OF HAMILTON AND NORTHERN HERKIMER COUNTIES...LIKELY
POPS ARE FORECAST SUNDAY INTO SUNDAY NIGHT...WITH CHANCE TO SLIGHT
CHANCE POPS ELSEWHERE. SNOWFALL AMOUNTS MAY REACH 4 TO 5 INCHES WITH
THIS EVENT ACROSS PARTS OF THE ADIRONDACKS...BUT IT WILL BE SPREAD
OUT OVER 24 TO 36 HOURS SO HAVE NOT ISSUED ANY ADVISORIES AT THIS
TIME...AND NEITHER HAVE ANY OF THE SURROUNDING OFFICES.
AFTER THE LOW MOVES TO THE EAST...A LARGE HIGH PRESSURE SYSTEM WILL
TAKER CONTROL OF OUR WEATHER FOR MONDAY AND MONDAY NIGHT. THIS WILL
NOT BE A VERY COLD AIRMASS SO TEMPS WILL BE NEAR OR ABOVE NORMAL
DURING THAT TIME.
FOR TEMPS...HIGHS SUNDAY WILL BE IN THE 30S. LOWS SUNDAY NIGHT IN
THE TEENS TO MID 20S. HIGHS MONDAY IN THE 20S TO MID 30S...AND LOWS
MONDAY NIGHT IN THE UPPER SINGLE NUMBERS AND TEENS AS CLEAR SKIES
AND LIGHT WINDS ALLOW FOR GOOD RADIATIONAL COOLING.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL DOMINATE MUCH OF THE LONG TERM PERIOD BEFORE A
POTENTIAL STORM SYSTEM APPROACHES LATE NEXT WEEK.
HIGH PRESSURE WILL BE SITUATED OVER THE EASTERN THIRD OF THE CONUS
AS A DEEP UPPER-LEVEL TROUGH DEVELOPS OVER THE WEST COAST TO START
THE LONG TERM PERIOD. THIS AREA OF HIGH PRESSURE WILL BEGIN TO SLIDE
OFF THE EASTERN SEABOARD TUESDAY...ALLOWING A MILD
WEST-SOUTHWESTERLY RETURN FLOW TO DEVELOP ACROSS THE AREA.
TEMPERATURES LOOK TO REBOUND NICELY FROM THE ARCTIC AIRMASS THAT
PRODUCED THE COLD TEMPERATURES DURING THE PREVIOUS WEEK.
EXPECT THE TUESDAY-THURSDAY MORNING TIMEFRAME TO BE DRY FOR MOST OF
THE FORECAST AREA...HOWEVER MENTIONED SLIGHT CHANCE POPS FOR
NORTHERN AREAS AS THE 12Z GFS/ECMWF DEPICT A WEAK SHORTWAVE DIPPING
SOUTH OUT OF THE NORTHERN STREAM FLOW THAT COULD SPAWN A FEW SNOW
SHOWERS IN THE SOUTHERN ADIRONDACKS.
A STORM SYSTEM WILL EJECT OUT OF THE PLAINS AND MIDWEST DURING
MIDWEEK...HOWEVER THERE ARE STILL SIGNIFICANT TIMING AND QPF
DIFFERENCES AMONGST THE GUIDANCE...USED A BLENDED APPROACH TO
ACCOUNT FOR THESE DIFFERENCES. REGARDLESS...HAVE CHANCE POPS FOR THE
THURSDAY NIGHT-FRIDAY MORNING TIMEFRAME AS GUIDANCE IS HONING IN ON
THIS TIMEFRAME BEING ASSOCIATED WITH THE FRONTAL PASSAGE. CURRENT
THERMAL PROFILES MAINLY SUGGEST A RAIN EVENT...ALTHOUGH THERE COULD
BE A MIX OF RAIN AND SNOW TOWARDS DAYBREAK FRIDAY MORNING.
TEMPERATURES ARE EXPECTED TO BE ABOVE AVERAGE DURING THE LONG TERM
PERIOD WITH HIGHS GENERALLY IN THE LOW TO MID 40S IN VALLEY REGIONS
AND MID TO UPPER 30S IN THE HIGHER TERRAIN BEGINNING WEDNESDAY AND
LASTING THROUGH THE REMAINDER OF THE LONG TERM PERIOD. LOWS WILL
GENERALLY BE IN THE MID 20S IN THE HIGHER TERRAIN TO LOW 30S IN
VALLEY LOCATIONS.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
WEAK WARM ADVECTION ASSOCIATED WITH AN APPROACHING FRONTAL
SYSTEM/UPPER LEVEL SHORTWAVE WILL ALLOW MID LEVEL CLOUDS TO CONTINUE
TO THICKEN AND LOWER FOR THE REMAINDER OF THE NIGHT. UPSTREAM RADARS
SHOWS SOME LIGHT SNOW SHOWERS/FLURRIES...BUT MUCH OF THIS ACTIVITY
LOOKS TO HAVE A DIFFICULT TIME MAKING ITS WAY TO THE SURFACE THANKS
TO THE DRY AIR IN PLACE AT LOW LEVELS. HIRES MESOSCALE MODELS
SUGGEST THESE SNOW SHOWERS MAY AFFECT OUR AREA BETWEEN 08Z-12Z...SO
WILL INCLUDE A VCSH DURING THIS TIME PERIOD. HAVE ALSO INCLUDED A
TEMPO FOR MVFR VSBYS IN CASE A BRIEF PERIOD OF LOWER VSBYS OCCUR
WITHIN ANY SNOW SHOWER...BUT IFR CONDITIONS ARE NOT ANTICIPATED AT
THIS TIME. CIGS SHOULD LOWER TO ABOUT 4-6 KFT TOWARDS THE END OF THE
NIGHT WITH THE PASSING WARM FRONT. WINDS FOR THE REMAINDER OF THE
LIGHT WITH BE SOUTHERLY AND VERY LIGHT /5 KTS OR LESS/ OR CALM.
THE BEST WARM AIR ADVECTION WILL SHIFT EAST OF THE REGION FOR DURING
THE DAY SUNDAY...PUTTING OUR AREA IN A LULL FOR PRECIPITATION. AS A
RESULT...WILL NOT MENTION A VCSH DURING THE DAY SUNDAY WITH JUST
SOME LINGERING BKN LOW AND MID LEVEL CLOUDS AND CONTINUED VFR
CONDITIONS. SOUTHERLY AREAS...SUCH AS AROUND KPOU...MAY HAVE CLOUDS
SCT OUT FOR THE AFTN HOURS. LIGHT SW WINDS OF 7 KTS OR LESS WILL BE
IN PLACE THROUGHOUT THE AREA.
THE STORM/S COLD FRONT LOOKS TO APPROACH THE AREA FOR SUNDAY
EVENING/OVERNIGHT...SO WILL HAVE BKN-OVC CIGS OF 4-7 KFT AND INCLUDE
A MENTION OF VCSH...ALTHOUGH THE BEST CHC FOR -SHSN WILL BE ACROSS
THE HIGHER TERRAIN. FLYING CONDITIONS LOOK TO STAY VFR FOR THE
MAJORITY OF THE TIME. WESTERLY WINDS WILL BE AROUND 5 KTS.
OUTLOOK...
MON-WED...VFR. NO SIG WX.
THU...VFR/MVFR. CHC -RASN.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE EXPECTED THE NEXT 5 DAYS RELATED TO QPF...AS
MAINLY DRY WEATHER OR SNOW PRODUCING SYSTEMS WILL IMPACT THE ALBANY
HYDRO SERVICE AREA /HSA/. MOST OF THESE WILL BE RATHER LIGHT.
SOME RIVER GAGES ARE EXHIBITING SIGNS OF ICE EFFECTS...AND RIVER
LEVEL READINGS LOOK UNREPRESENTATIVE. ICE WILL CONTINUE TO FORM
AND THICKEN ON ALL WATERWAYS IN THE ALY HSA THROUGH THE WEEKEND.
WE WILL HAVE TO MONITOR FOR ANY FREEZE UP JAMS...ESPECIALLY ALONG
THE NRN PERIPHERY OF THE HSA.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SND/GJM
NEAR TERM...BGM/SND/GJM
SHORT TERM...GJM
LONG TERM...IRL
AVIATION...FRUGIS
HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
940 AM EST SUN JAN 6 2013
.DISCUSSION...
CURRENT...FOG AND LOW CLOUDS WERE LIFTING ALONG THE COAST WHILE
INLAND FOG AND/OR LOW CLOUDS WERE STILL A PROBLEM. EXPECT THAT THE
FOG AND LOW CLOUDS OVER THE INTERIOR WILL HAVE LIFTED BETWEEN
10AM/15Z AND 11AM/16Z. THIS MATCHES WELL WITH THE 10AM EXPIRATION OF
THE DENSE FOG ADVISORY.
THE WEST PALM BEACH AIRPORT RADAR WAS DETECTING SHOWERS MOVING SOUTH
TO NORTH ALONG THE IMMEDIATE MARTIN AND SAINT LUCIE COAST WEST TO
INTERSTATE 95.
LATEST RUC40 GUIDANCE RUN WAS SHOWING LITTLE MID LEVEL SUPPORT FOR
ANYTHING MORE THAN ISOLATED SHOWERS THIS MORNING AND EARLY
AFTERNOON. WENT WITH THAT SUGGESTION AND AMENDED THE WEATHER GRID
OUT TO 2PM/19Z TO REFLECT ISOLATED SHOWERS TO MID AFTERNOON THEN
START THE MORE SIGNIFICANT WEATHER MID TO LATE AFTERNOON.
SAME RUC RUN ALSO INDICATING THAT THE BEST ISENTROPIC LIFT SHOULD
START DURING THE AFTERNOON WITH THE STATIONARY BOUNDARY HAVING
STARTED MOVING AGAIN AS A WARM FRONTAL BOUNDARY.
&&
.AVIATION...VFR THROUGH LATE AFTERNOON. PREVAILING MVFR CEILINGS
LATE AFTERNOON AND OVERNIGHT AS LIGHT RAIN IS EXPECTED TO START.
&&
.MARINE...
CURRENT...THE NOAA BUOYS WERE RECORDING LIGHT WINDS FROM THE
NORTHEAST TO THE SOUTHEAST AND 3 FOOT SEAS. THE TWO SCRIPPS BUOYS
WERE RECORDING 2 FOOT SEAS.
THIS AFTERNOON...WINDS SHOULD REMAIN LIGHT WITH THE FRONTAL BOUNDARY
IN THE AREA. ISOLATED SHOWERS SOUTH OF FORT PIERCE INLET THIS
MORNING AND EARLY AFTERNOON. SHOWERS...SLIGHT CHANCE OF A LIGHTNING
STORM THIS AFTERNOON AND EVENING.
PREVIOUS MARINE DISCUSSION
TODAY-TONIGHT...WEAK FRONTAL BOUNDARY LIFTING NORTH OVER
WATERS THIS MORNING...CURRENTLY LOCATED AROUND CAPE CANAVERAL. WINDS
WILL BE SOUTH-SOUTHEAST AT 10-15KTS SOUTH OF THE BOUNDARY AND E-NE
5KTS NORTH OF THE BOUNDARY. BOUNDARY IS EXPECTED TO STALL OVER THE
VOLUSIA COUNTY WATERS THIS AFTERNOON...BEFORE GETTING PUSHED BACK
TO THE SOUTH OVERNIGHT. WINDS WILL TURN N-NW BEHIND THE RETREATING
FRONT...WITH A WIND SURGE INCREASING SPEEDS TO 15-20KTS TOWARDS
DAYBREAK MONDAY. SEAS 2-3FT UNDER CHOPPY 5-6SEC PERIODS. PRESENCE OF
THE BOUNDARY WILL LEAD TO SCT-NMRS SHOWERS THROUGH THE PERIOD WITH
ISOLD TSTMS POSSIBLE THIS AFTERNOON AND OVERNIGHT...MAINLY OVER THE
WARMER GULF STREAM WATERS.
MON-THU...POST FRONTAL NE-E SURGE A LITTLE LESS ROBUST THAN EARLIER
PROGGED...WITH WINDS/SEAS NOW FCST TO REMAIN A LITTLE BELOW SCA CUSP
OF 20KT/7FT FOR THE NORTHERN HALF CWA THROUGH MONDAY EVENING...SO IT
SEEMS CAUTIONARY STMT NORTH OF SEBASTIAN MAY BE MORE LIKELY SCENARIO
FOR MON-MON EVENING. WINDS/SEAS GENERALLY STAY IN THE 12-18KT AND
3-5FT RANGE AS THE LOW LEVEL FLOW VEERS FROM E TO SE BY MID-LATE
WEEK.
&&
FPR 80 61 76 64 / 20 60 30 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
UPDATES/AVIATION...WIMMER
IMPACT WX/RADAR....KELLY
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
621 AM CST SUN JAN 6 2013
.UPDATE...
UPDATED FOR AVIATION DISCUSSION BELOW.
&&
.PREV DISCUSSION.../ISSUED AT 347 AM CST SUN JAN 6 2013/
ONE THING THAT LOOKS CERTAIN IS THAT WE WILL GET A NICE JANUARY
THAW COMING UP THIS WEEK. WHERE THERE ARE STILL QUESTIONS IS HOW
WARM IS SAID THAW...AND IS IT ACCOMPANIED WITH RAIN IN THE THU/FRI
TIMEFRAME. QUESTION MARKS DO NOT GO AWAY FOR THE WEEKEND IN TERMS
OF THE WEATHER...WITH THE ONLY THING THAT LOOKS CERTAIN BY THE END
OF THE WEEK INTO NEXT WEEKEND IS THAT THE MID SECTION OF THE
COUNTRY LOOKS TO BE MORE ACTIVE.
THE THAW IS COMING...JUST NOT TODAY. SFC LOW AT 3 AM WAS NEAR THE
MACKINAC STRAIGHTS. SEEING WIDESPREAD STRATUS ACROSS NRN MN
WITHIN CYCLONIC FLOW BEHIND THIS LOW. THIS STRATUS IS MAKING
INROADS SOUTH AND SHOULD BLANKET MUCH OF NW QUARTER OF THE MPX
CWA BY DAYBREAK. FOR NOW HAVE CLOUDS THINNING DURING THE
MORNING...WITH MOSTLY SUNNY SKIES INDICATED BY THE AFTERNOON...BUT
THE RAP /PER 925-850 MB RH/ KEEPS THE CLOUDS IN PLACE THROUGH THE
DAY. CERTAINLY WOULD NOT BE THE FIRST TIME STRATUS GOT TRAPPED
UNDER A DEVELOPING INVERSION...WHICH WE WILL SEE THANKS TO 12 HR
H5 HEIGHT RISES IN EXCESS OF 120M BY THE AFTERNOON. EVEN WITHOUT
THE CLOUD COVER...COOLER AIR THAT ARRIVED OVERNIGHT WILL HELP HOLD
TEMPERATURES TODAY BACK INTO THE TEENS AND 20S.
TONIGHT...WINDS WILL TURN OUT OF THE SW AND SHOULD BE QUITE STRONG
RIGHT THROUGH THE EVENING OUT AHEAD OF COLD THAT WILL BE MOVING
ACROSS NODAK. LLJ OUT AHEAD THE FRONT PROGGED BY THE GFS/NAM TO
BE AROUND 60 KTS...SO THIS WILL QUICKLY BRING WARMER AIR BACK INTO
THE REGION...WITH 925 MB TEMPS GETTING BACK UP AROUND THE 0C MARK
BY MONDAY AFTERNOON. THE ONLY THING HOLDING THE AREA BACK FROM
SEEING HIGHS IN THE MID AND EVEN UPPER 30S IS THE COLD FRONT
QUICKLY MOVE THROUGH IN THE MORNING...BUT STILL SHOULD SEE HIGHS A
FEW DEGS ON EITHER SIDE OF 30.
FOR TUESDAY...A FAIRLY SHARP AND NEGATIVELY TILTED H5 TROUGH IS
STILL FORECAST TO SWING THROUGH THE REGION. HAVE SEEN A SLIGHT SRN
SHIFT WITH THE ECMWF TOWARD THE GFS WITH QPF WITH THIS
WAVE...THOUGH IT STILL KEEPS QPF NORTH OF THE MPX CWA...WHERE IT
TAKES THE PV ANOMALY. THE FIM/GFS AND EVEN THE 06.00 GEM ARE NOW
BRINGING SOME PRECIP INTO THE NRN HALF OF THE MPX CWA. AT THIS
POINT...KEPT POPS BELOW 15% THOUGH DID ADD A MENTION OF SCT
FLURRIES ACROSS CENTRAL MN. MAIN REASON FOR NOT INCLUDING
MENTIONABLE POPS IS THAT THE PRIMARY SFC LOW...EVEN ON THE SRN
OUTLIER GFS IS PROGGED TO GO ACROSS SRN CANADA...WHICH WOULD HELP
KEEP BETTER PRECIP CHANCES UP ALONG THE INTERNATIONAL BORDER. EVEN
IF SNOW WERE TO OCCUR...IT WOULD BE ANOTHER HALF INCH OR LESS TYPE
SNOWFALL.
MODELS MAINTAIN DECENT AGREEMENT ON THE PROGRESSION OF THINGS NEXT
WEEK THROUGH WEDNESDAY...BUT QUICKLY DIVERGE AFTER THAT...WITH
EVEN RUN-TO-RUN CONSISTENCY WITHIN INDIVIDUAL MODELS BEING LESS
THAN IDEAL. AT ISSUE IS HOW THEY HANDEL THE CLOSED H5 LOW THAT IS
CURRENTLY NEAR SAN FRANCISCO. BY WEDNESDAY...THIS LOW WILL BE NEAR
THE BIG BEND REGION OF TX AS A DEEP AND POSITIVELY TILTED TROUGH
WORKS DOWN THE WEST COAST. AS ALL OF THIS IS GOING ON...AN
IMPRESSIVE RIDGE WILL BE BUILDING ACROSS THE ERN CONUS...WITH 590
DM HEIGHTS EXPECTED OVER FLA AND THE 576 DM LINE CLEAR UP TO THE
WI/IL BORDER. WHERE MODELS DIVERGE IS THE EXTENT WHICH THE CLOSED
LOW WILL INTERACT WITH THE WEST COAST TROUGH. OVER THE PAST 24 HRS
THE GFS AND ECMWF HAVE TRADED POSITIONS ON HOW TO HANDEL THE
WAVE...WITH THE GFS NOW BRINGING THE WAVE NORTH TOWARD THE GREAT
LAKES BY FRIDAY...WITH THE ECMWF TAKING THE WAVE ACROSS THE OHIO
VALLEY. THE GEM/FIM ARE MORE IN LINE WITH THE GFS...THOUGH A
LITTLE SLOWER. AT THIS POINT...GIVEN THE STRENGTH OF THE RIDGE
EXPECTED OVER THE SE...FIND IT HARD TO BELIEVE THE ECMWF SOLUTION
THAT IT WILL PLOW RIGHT THROUGH THE RIDGE AND WOULD FAVOR THE MORE
WRN SOLUTIONS. WHERE THERE IS AGREEMENT HOWEVER WITH THE
MODELS...IS THAT WHEREVER THE PRECIPITATION GOES...THICKNESSES
WILL BE WARM ENOUGH ACROSS THE MPX CWA FOR ALL RAIN ON THURSDAY.
IN FACT...MODELS DELAY THE ONSET OF THE COLD AIR BY A DAY
NOW...WITH THE ECMWF AND GEM SHOWING HIGHS IN THE 40S ON FRIDAY
ACROSS THE ERN HALF OF THE CWA...WHICH MEANS ANY TRANSITION BACK
TO SNOW POSSIBLY WAITING UNTIL AS LATE AS FRIDAY NIGHT OR
SATURDAY.
BESIDE THE POTENTIAL FOR RAIN...TEMPERATURE AND DEWPOINT FORECASTS
THURSDAY AND FRIDAY SHOW THE POTENTIAL FOR SOME AGGRESSIVE SNOW
MELT FOR JANUARY STANDARDS. BESIDE HIGHS POSSIBLY PUSHING 40 ONE
OR BOTH OF THE DAYS...THURSDAY NIGHT MAY SEE LOWS STAY ABOVE
FREEZING...WITH DEWPOINTS EVEN GETTING INTO THE MID/UPPER 30S.
EVEN WITHOUT ANY RAIN...THESE CONDITIONS WILL LIKELY LEAVE BARE
SPOTS IN THE SNOW COVER BY THIS WEEKEND.
AS FOR THE WEEKEND...MODEL AGREEMENT GETS NO BETTER. ABOUT ALL ONE
CAN SAY IS THAT THE WRN TROUGH WILL CONTINUE TO PUSH EAST...AND AS
IT DOES SO...MORE SEASONABLE AIR WILL MAKE A RETURN...WITH SOME
SNOW STILL LOOKING POSSIBLE.
&&
.AVIATION.../12Z TAF ISSUANCE/
TWO AREAS OF CIGS TO BE CONCERNED ABOUT THIS MORNING. ONE IS OVER
WRN WI AND IS PRIMARILY MVFR. THE OTHER IS A NARROW FINGER OF
IFR CIGS ACROSS WRN MN. RAP13 SEEMS TO HAVE A GOOD HANDLE ON THESE
AREAS...SO FOLLOWED THIS SOLUTION WITH A FEW TWEAKS TOWARD THE
LAMP GUIDE. THE CIGS OVER WRN MN SHOULD SLIDE EAST SLOWLY THIS
MORNING AND BEGIN DISSIPATING. THE BACK EDGE IS ABOUT OVER RWF
AND SHOULD CLEAR AXN AROUND 14-15Z. IT WILL HOWEVER BEGIN TO AFFECT
STC AROUND 13Z...AND REMAIN NEARLY STATIONARY UNDER THE RIDGE AXIS
THROUGH THE MORNING BEFORE DISSIPATING SOMETIME AROUND 18Z.
FURTHER EAST...RNH AND MSP SHOULD BE VFR THROUGH THE PERIOD BEING
SANDWICHED BETWEEN THE TWO AREAS OF STRATUS. FINALLY...EAU WILL
SEE IMPROVING CONDITIONS AS THE MVFR STRATUS ROTATES OUT TO THE
EAST THIS MORNING.
WINDS ARE EXPECTED TO TURN SOUTHERLY AND STRENGTHEN THIS EVENING.
FORECAST SOUNDINGS STILL INDICATE THE POTENTIAL FOR 50+ KT WINDS
ABOVE 1000FT. A PRETTY DEEP INVERSION SHOULD DAMPEN WIND GUST
POTENTIAL TO LESS THAN 25 KTS AT THE SURFACE AND HAS ALLOWED THE
EXCLUSION OF WIND SHEAR MENTION ATTM.
KMSP...VFR CONDITIONS EXPECTED AS TWO AREAS OF STRATUS LIKELY REMAIN
REMOVED FROM THE VICINITY OF THE TERMINAL. NORTHWEST WINDS WILL
BACK SOUTHWEST THIS AFTERNOON AND TO SOUTH TONIGHT. SPEEDS WILL
REMAIN LIGHT THROUGH TODAY...THEN INCREASE WITH LLJ PUSHING
OVERHEAD TONIGHT.
/OUTLOOK FOR KMSP/
MON...VFR. WINDS SW 10 KTS.
TUE...VFR. WINDS SE 4-8 KTS.
WED...VFR. WINDS S 10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
MPG/BORGHOFF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
347 AM CST SUN JAN 6 2013
.DISCUSSION...
ONE THING THAT LOOKS CERTAIN IS THAT WE WILL GET A NICE JANUARY
THAW COMING UP THIS WEEK. WHERE THERE ARE STILL QUESTIONS IS HOW
WARM IS SAID THAW...AND IS IT ACCOMPANIED WITH RAIN IN THE THU/FRI
TIMEFRAME. QUESTION MARKS DO NOT GO AWAY FOR THE WEEKEND IN TERMS
OF THE WEATHER...WITH THE ONLY THING THAT LOOKS CERTAIN BY THE END
OF THE WEEK INTO NEXT WEEKEND IS THAT THE MID SECTION OF THE
COUNTRY LOOKS TO BE MORE ACTIVE.
THE THAW IS COMING...JUST NOT TODAY. SFC LOW AT 3 AM WAS NEAR THE
MACKINAC STRAIGHTS. SEEING WIDESPREAD STRATUS ACROSS NRN MN
WITHIN CYCLONIC FLOW BEHIND THIS LOW. THIS STRATUS IS MAKING
INROADS SOUTH AND SHOULD BLANKET MUCH OF NW QUARTER OF THE MPX
CWA BY DAYBREAK. FOR NOW HAVE CLOUDS THINNING DURING THE
MORNING...WITH MOSTLY SUNNY SKIES INDICATED BY THE AFTERNOON...BUT
THE RAP /PER 925-850 MB RH/ KEEPS THE CLOUDS IN PLACE THROUGH THE
DAY. CERTAINLY WOULD NOT BE THE FIRST TIME STRATUS GOT TRAPPED
UNDER A DEVELOPING INVERSION...WHICH WE WILL SEE THANKS TO 12 HR
H5 HEIGHT RISES IN EXCESS OF 120M BY THE AFTERNOON. EVEN WITHOUT
THE CLOUD COVER...COOLER AIR THAT ARRIVED OVERNIGHT WILL HELP HOLD
TEMPERATURES TODAY BACK INTO THE TEENS AND 20S.
TONIGHT...WINDS WILL TURN OUT OF THE SW AND SHOULD BE QUITE STRONG
RIGHT THROUGH THE EVENING OUT AHEAD OF COLD THAT WILL BE MOVING
ACROSS NODAK. LLJ OUT AHEAD THE FRONT PROGGED BY THE GFS/NAM TO
BE AROUND 60 KTS...SO THIS WILL QUICKLY BRING WARMER AIR BACK INTO
THE REGION...WITH 925 MB TEMPS GETTING BACK UP AROUND THE 0C MARK
BY MONDAY AFTERNOON. THE ONLY THING HOLDING THE AREA BACK FROM
SEEING HIGHS IN THE MID AND EVEN UPPER 30S IS THE COLD FRONT
QUICKLY MOVE THROUGH IN THE MORNING...BUT STILL SHOULD SEE HIGHS A
FEW DEGS ON EITHER SIDE OF 30.
FOR TUESDAY...A FAIRLY SHARP AND NEGATIVELY TILTED H5 TROUGH IS
STILL FORECAST TO SWING THROUGH THE REGION. HAVE SEEN A SLIGHT SRN
SHIFT WITH THE ECMWF TOWARD THE GFS WITH QPF WITH THIS
WAVE...THOUGH IT STILL KEEPS QPF NORTH OF THE MPX CWA...WHERE IT
TAKES THE PV ANOMALY. THE FIM/GFS AND EVEN THE 06.00 GEM ARE NOW
BRINGING SOME PRECIP INTO THE NRN HALF OF THE MPX CWA. AT THIS
POINT...KEPT POPS BELOW 15% THOUGH DID ADD A MENTION OF SCT
FLURRIES ACROSS CENTRAL MN. MAIN REASON FOR NOT INCLUDING
MENTIONABLE POPS IS THAT THE PRIMARY SFC LOW...EVEN ON THE SRN
OUTLIER GFS IS PROGGED TO GO ACROSS SRN CANADA...WHICH WOULD HELP
KEEP BETTER PRECIP CHANCES UP ALONG THE INTERNATIONAL BORDER. EVEN
IF SNOW WERE TO OCCUR...IT WOULD BE ANOTHER HALF INCH OR LESS TYPE
SNOWFALL.
MODELS MAINTAIN DECENT AGREEMENT ON THE PROGRESSION OF THINGS NEXT
WEEK THROUGH WEDNESDAY...BUT QUICKLY DIVERGE AFTER THAT...WITH
EVEN RUN-TO-RUN CONSISTENCY WITHIN INDIVIDUAL MODELS BEING LESS
THAN IDEAL. AT ISSUE IS HOW THEY HANDEL THE CLOSED H5 LOW THAT IS
CURRENTLY NEAR SAN FRANCISCO. BY WEDNESDAY...THIS LOW WILL BE NEAR
THE BIG BEND REGION OF TX AS A DEEP AND POSITIVELY TILTED TROUGH
WORKS DOWN THE WEST COAST. AS ALL OF THIS IS GOING ON...AN
IMPRESSIVE RIDGE WILL BE BUILDING ACROSS THE ERN CONUS...WITH 590
DM HEIGHTS EXPECTED OVER FLA AND THE 576 DM LINE CLEAR UP TO THE
WI/IL BORDER. WHERE MODELS DIVERGE IS THE EXTENT WHICH THE CLOSED
LOW WILL INTERACT WITH THE WEST COAST TROUGH. OVER THE PAST 24 HRS
THE GFS AND ECMWF HAVE TRADED POSITIONS ON HOW TO HANDEL THE
WAVE...WITH THE GFS NOW BRINGING THE WAVE NORTH TOWARD THE GREAT
LAKES BY FRIDAY...WITH THE ECMWF TAKING THE WAVE ACROSS THE OHIO
VALLEY. THE GEM/FIM ARE MORE IN LINE WITH THE GFS...THOUGH A
LITTLE SLOWER. AT THIS POINT...GIVEN THE STRENGTH OF THE RIDGE
EXPECTED OVER THE SE...FIND IT HARD TO BELIEVE THE ECMWF SOLUTION
THAT IT WILL PLOW RIGHT THROUGH THE RIDGE AND WOULD FAVOR THE MORE
WRN SOLUTIONS. WHERE THERE IS AGREEMENT HOWEVER WITH THE
MODELS...IS THAT WHEREVER THE PRECIPITATION GOES...THICKNESSES
WILL BE WARM ENOUGH ACROSS THE MPX CWA FOR ALL RAIN ON THURSDAY.
IN FACT...MODELS DELAY THE ONSET OF THE COLD AIR BY A DAY
NOW...WITH THE ECMWF AND GEM SHOWING HIGHS IN THE 40S ON FRIDAY
ACROSS THE ERN HALF OF THE CWA...WHICH MEANS ANY TRANSITION BACK
TO SNOW POSSIBLY WAITING UNTIL AS LATE AS FRIDAY NIGHT OR
SATURDAY.
BESIDE THE POTENTIAL FOR RAIN...TEMPERATURE AND DEWPOINT FORECASTS
THURSDAY AND FRIDAY SHOW THE POTENTIAL FOR SOME AGGRESSIVE SNOW
MELT FOR JANUARY STANDARDS. BESIDE HIGHS POSSIBLY PUSHING 40 ONE
OR BOTH OF THE DAYS...THURSDAY NIGHT MAY SEE LOWS STAY ABOVE
FREEZING...WITH DEWPOINTS EVEN GETTING INTO THE MID/UPPER 30S.
EVEN WITHOUT ANY RAIN...THESE CONDITIONS WILL LIKELY LEAVE BARE
SPOTS IN THE SNOW COVER BY THIS WEEKEND.
AS FOR THE WEEKEND...MODEL AGREEMENT GETS NO BETTER. ABOUT ALL ONE
CAN SAY IS THAT THE WRN TROUGH WILL CONTINUE TO PUSH EAST...AND AS
IT DOES SO...MORE SEASONABLE AIR WILL MAKE A RETURN...WITH SOME
SNOW STILL LOOKING POSSIBLE.
&&
.AVIATION... /06Z TAF ISSUANCE/
PATCHY MVFR CEILINGS FROM KSTC THROUGH THE TWIN CITIES AND
EASTWARD INTO WEST CENTRAL WI WILL CONTINUE TO MEANDER SE EARLY IN
THE TAF PERIOD IN THE WAKE OF A COLD FRONT. A SMALL BREAK EXISTS TO
THE WEST BEFORE MORE WIDESPREAD MVFR CEILINGS ARE PUSHING IN FROM
THE DAKOTAS NEAR 20 KNOTS. SHORT TERM GUIDANCE SUGGESTS THIS
CLOUDINESS WILL REACH INTO KAXN BY 08Z AND INTO KRWF AND KSTC
AROUND 10Z. THIS WILL LIKELY PERSIST THROUGH DAYBREAK BEFORE
DIMINISHING DURING THE MORNING AS THE LOW LEVEL FLOW BECOMES MORE
ANTICYCLONIC. VFR CONDITIONS FOR THE AFTERNOON AND EVENING AS A
RIDGE OF HIGH PRESSURE MOVES BY. THE PRESSURE GRADIENT WILL TIGHTEN
SUNDAY NIGHT WITH SOUTH WINDS INCREASING TO NEAR 15 KNOTS FOR KRWF
AND KAXN. THIS GRADIENT WILL SPREAD INTO THE EASTERN TAF SITES
DURING THE NIGHT. WINDS MONDAY MORNING AT 1500 FEET ARE PROJECTED
TO BE NEAR 50 KNOTS.
KMSP...PATCHY MVFR CEILINGS WILL OCCUR EARLY THIS MORNING.
CEILINGS NEAR 015 SHOULD BEGIN MOVING IN BETWEEN 07Z-09Z.
CONFIDENCE INCREASING THAT THESE LOWER MVFR CEILINGS WILL PERSIST
INTO THE MID MORNING HOURS. VFR FOR THE AFTERNOON AND NIGHT.
NORTHWEST WINDS 6-9 KNOTS OVERNIGHT AND SUNDAY MORNING BACKING TO
THE WEST IN THE AFTERNOON AND THEN TO SOUTH 12 KNOTS SUNDAY NIGHT.
/OUTLOOK FOR KMSP/
MON...VFR. WINDS SW 12-15 KTS GUSTING 20 KTS.
TUE...VFR. WINDS S 4-8 KTS.
WED...VFR. WINDS WSW 5 TO 10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
MPG/RAH
AREA FORECAST DISCUSSION
NWS DULUTH MN
1136 PM CST SAT JAN 5 2013
.AVIATION.../06Z TAF ISSUANCE/
SKY COVER WILL CONTINUE TO DECREASE THIS MORNING FROM THE
WEST...WITH A MVFR DECK SCTRG OUT AT KDLH BY 12Z AND KHYR BY 15Z.
WEAK RIDGING ACROSS THE NORTHLAND WILL THEN RESULT IN VFR
CONDITIONS FOR THE REST OF THE TAF PERIOD. WINDS WILL BECOME
MAINLY LIGHT AND VARIABLE LATER THIS MORNING...THEN TURN OUT OF
THE SOUTHWEST AND STRENGTHEN BY LATE SUNDAY AFTERNOON...ESPECIALLY
ACROSS OUR WRN ZONES TO DULUTH.
&&
.PREV DISCUSSION... /ISSUED 723 PM CST SAT JAN 5 2013/
UPDATE...
LOW PRESSURE IN UPPER MICHIGAN CONTINUE TO MOVE EAST THIS
EVENING...WITH WINDS BECOMING NORTH OVER LAKE SUPERIOR...AND LOWER
CLOUDS MOVING OVER NORTHERN WISCONSIN AS WELL. MORE CLOUDS OVER
THE RED RIVER VALLEY WERE MOVING E-SE THIS EVENING...AND THE RAP
900-925MB CONDENSATION PRESSURE DEFICITS WERE HANDLING THIS PRETTY
WELL...AND IT BRINGS THESE CLOUDS TO OUR WESTERN BORDER LATE
TONIGHT. WE`LL HAVE TO KEEP AN EYE ON THESE AND INCREASE CLOUD
COVER IF THEY HAPPEN TO MOVE IN FASTER.
WE DON`T PLAN ON ANY MAJOR CHANGES TO THE GRIDS OVERNIGHT...WE
STILL EXPECT LAKE EFFECT SNOW SHOWERS TO DEVELOP IN THE
SNOWBELT...MAINLY IN IRON/ASHLAND COUNTIES. WE DID INCREASE
SNOWFALL A BIT OVER IRON COUNTY AS INVERSION LEVELS INCREASE
TONIGHT WITH DELTA-T`S FORECAST TO ABOUT 15-17C.
PREV DISCUSSION... /ISSUED 535 PM CST SAT JAN 5 2013/
AVIATION...00Z TAFS
IFR/LOW MVFR CEILINGS COVERED MUCH OF NORTHEAST MINNESOTA...AND
THEY WERE WORKING THEIR WAY SOUTH INTO NORTHWEST WISCONSIN AS
WELL. MORE LOW CEILINGS WERE OVER PORTIONS OF EASTERN NORTH
DAKOTA. WE EXPECT THOSE CEILINGS WILL WORK EAST THROUGH THE
NIGHT...BUT THE RAP WHICH IS HANDLING THEM PRETTY WELL...KEEPS
THEM WEST OF KINL/KBRD THROUGH 14Z. A SURFACE LOW OVER WESTERN
UPPER MICHIGAN WILL CONTINUE TO MOVE OFF TONIGHT...DRAWING THOSE
LOWER CEILINGS SOUTH AND EAST. WE KEPT THE MENTION OF THESE CLOUDS IN
THE KDLH/KHIB TAFS THROUGH ABOUT 7-8Z...AND UNTIL 15Z AT KHYR.
MOST AREAS WILL BE VFR ON SUNDAY...OUTSIDE OF SOME LAKE CLOUDS
ALONG THE SOUTH SHORE.
PREV DISCUSSION... /ISSUED 251 PM CST SAT JAN 5 2013/
SHORT TERM...
THIS AFTERNOON/TONIGHT THROUGH SUNDAY NIGHT...
MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND THE CHANCE OF
LIGHT SNOW EXPECTED TO DEVELOP THIS EVENING ACROSS NE MN AND
LINGER THROUGH NW WI INTO SUNDAY MORNING...ALONG WITH TEMPERATURES
THROUGH THE NEAR TERM.
ATMOSPHERE REMAINS FAIRLY DRY ACROSS THE REGION WITH A SHARP UPPER
TROUGH OVER THE RED RIVER VALLEY MOVING EWD INTO NRN MN THIS
AFTERNOON. BENIGN SFC LOW CURRENTLY POSITIONED NEAR LAKE MILLE
LACS WITH LITTLE IN THE WAY OF CLOUD COVER ASSOCIATED WITH IT
ATTM. LOW LEVEL FLOW PATTERN WITH EAST WINDS OFF LAKE SUPERIOR
INTO THE ARROWHEAD HAVE ALLOWED LOW CLOUDS TO PERSIST OVER THE NRN
THIRD OF THE FORECAST AREA TODAY. THIS AREA OF LOW CLOUDS WILL
COMBINE WITH THE INCOMING S/W AND INCREASE IN AREAL COVERAGE
BEFORE DEVELOPING LIGHT SNOW/FLURRIES ALONG AND EAST OF HIGHWAY 53
EARLY THIS EVENING. ONLY LIGHT OR TRACE ACCUMULATIONS ARE EXPECTED
OVER NE MN TONIGHT.
BY LATE THIS EVENING...THE BL FLOW ACROSS WRN LAKE SUPERIOR WILL
BECOME MORE NRLY AS THE SFC LOW SLIDES FURTHER TO THE EAST. THE
COMBINATION OF 15 TO 25 KT NORTH WINDS OFF THE LAKE WITH A LONG
FETCH OVER WATER...A RELATIVELY DEEP BL ROUGHLY 3-4K FT...AND
COLD ENOUGH TEMPS ALOFT TO PRODUCE MODEST LOW LVL
INSTABILITY...THE POTENTIAL FOR LIGHT LAKE EFFECT SNOW ALONG THE
SOUTH SHORE ARISES. LAKE TEMPS ARE AROUND +2.7 DEG C AND 850MB
TEMPS WILL BE -11 TO -12 DEG C. KEPT WITH PREVIOUS FORECAST OF
LIKELY POPS FROM NRN BAYFIELD TO NRN ASHLAND/IRON COUNTIES FROM
06-12Z LATE TONIGHT/EARLY SUN MORNING...AND GENERALLY 1-2 INCHES
OF SNOW IN THIS AREA.
HIGH PRESSURE QUICKLY BUILDS IN SUNDAY AFTERNOON AND ALLOWS
CONDITIONS TO DRY OUT. SHOULD SEE MOSTLY SUNNY TO PARTLY CLOUDY
SKIES FOR THE END OF THE WEEKEND.
LOW TEMPERATURES TONIGHT WILL BE SOMEWHAT TRICKY AS CLOUD COVER
COULD END UP BEING PATCHY IN NATURE OVER PARTS OF NE MN. WILL
LIKELY SEE SINGLE DIGITS ABOVE AND BELOW ZERO ACROSS NRN MN...WITH
A FEW TEENS BELOW ZERO NOT OUT OF THE QUESTION WHERE ADDITIONAL
CLEARING OCCURS. AREAS TO THE EAST IN NW WI WILL BE SLIGHTLY
WARMER WITH ADDITIONAL CLOUD COVER ALMOST CERTAIN. SHOULD SEE
LOWER TO MID TEENS IN THIS AREA. ON SUNDAY...A LINGERING COLD AIR
MASS WILL ONLY ALLOW TEMPS TO REACH INTO THE UPPER TEENS TO MID
20S...EVEN WITH MOSTLY SUNNY SKIES IN THE AFTERNOON. LOWS SUNDAY
NIGHT WILL DROP INTO THE UPPER SINGLE DIGITS AND TEENS ABOVE
ZERO...WITH HIGH CLOUDS MOVING IN FROM THE NW.
LONG TERM...
MONDAY THROUGH SATURDAY...
AN UNSEASONABLY MILD PATTERN WILL CONTINUE THROUGHOUT THE
EXTENDED TIME PERIOD ACROSS THE NORTHLAND. IT ALSO LOOKS FAIRLY
QUIET FOR THE MOST PART. LOW PRESSURE MOVING ACROSS THE CENTRAL
CANADIAN PROVINCES WILL AFFECT AREAS MAINLY NORTH OF THE BORDER ON
MONDAY AND MONDAY NIGHT...WITH A FAIR AMOUNT OF SUNSHINE FURTHER
SOUTH. THE MODELS DIVERGE QUITE A BIT IN HOW THEY HANDLE A SYSTEM
ON TUESDAY AND WEDNESDAY. THE ECMWF AND GEM ARE FAIRLY SIMILAR BUT
THE GFS SHOWS A LOW PRESSURE SYSTEM DEVELOPING IN CENTRAL NORTH
DAKOTA BY 00Z WEDNESDAY. THE RESULT COULD BE SOME SCATTERED SNOW
SHOWERS TUESDAY NIGHT AND WEDNESDAY AS THE SYSTEM MOVES THROUGH.
HIGH PRESSURE WILL GENERALLY CONTROL LATER WEDNESDAY AND WEDNESDAY
NIGHT. THURSDAY LOOKS QUITE MILD WITH TEMPS WELL INTO THE 30S
AHEAD OF LOW PRESSURE DEVELOPING IN THE NORTHERN ROCKIES. THERE
ARE SOME HUGE MODEL DIFFERENCES BEGINNING ON FRIDAY AND CONTINUING
INTO THE WEEKEND SO KEEPING POPS LOW FOR NOW. THE GFS CONTINUES TO
TRY TO DEVELOP A MAJOR LOW BY NEXT WEEKEND...WHICH WOULD IMPACT
OUR AREA. THE ECMWF IS MUCH FURTHER SE AND NOT NECESSARILY OF MUCH
CONCERN FOR OUR CWA. DEFINITELY SOMETHING TO KEEP AN EYE ON...AS
THE GFS HAS BEEN REASONABLY CONSISTENT.
&&
.POINT TEMPS/POPS...
DLH 8 20 10 30 / 20 0 0 10
INL -1 17 12 28 / 10 0 0 10
BRD 4 21 12 31 / 10 0 0 10
HYR 12 22 9 33 / 30 10 0 10
ASX 15 24 13 34 / 50 20 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 AM CST SUNDAY FOR LSZ121-146>148.
&&
$$
AVIATION...BERDES
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
522 PM CST MON JAN 7 2013
.AVIATION...
00Z TAFS FOR KOMA...KLNK...KOFK.
WILL HAVE TO MONITOR FOR DEVELOPMENT OF STRATUS AND FOG TONIGHT.
DID MENTION SOME MVFR VISIBILITIES LATER TONIGHT BUT DID NOT WANT
TO GET TOO PESSIMISTIC. GFS MODEL DOES NOT DEVELOP FOG...WHILE
THE NAM DOES. GENERALLY FELT THE NAM LOW LEVEL MOISTURE WAS
OVERDONE BUT WILL MONITOR AND AMEND TAFS THROUGH THE EVENING AS
NEEDED.
MILLER
&&
.PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY.
MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF
SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO
THURSDAY.
DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT
SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA...
TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN
SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW
FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON.
INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN
THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE
BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN
AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST.
FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL
TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING
TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A
WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL
EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE.
TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT
AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME
FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER
IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR
WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS
THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH
TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE
AREA AS RAIN CONTINUES.
FOBERT
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO
LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE
NEEDED TO GOING FCST.
HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER
IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT.
MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM
CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN
TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS
SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE
BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING
MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR
SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA
FRIDAY NIGHT.
ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL
SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT
VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND
LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH
SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA
DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD
VERIFY.
OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO
EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE
LOWER/MID 20S.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1001 AM EST SUN JAN 6 2013
.SYNOPSIS...
A WEAK AREA OF LOW PRESSURE WILL BRING MINOR SNOW ACCUMULATIONS TO
MOST LOCATIONS THIS AFTERNOON AND EVENING...BUT SNOWS WILL BE
A BIT STEADIER EAST OF LAKE ONTARIO. HIGH PRESSURE WILL THEN BUILD
INTO THE OHIO VALLEY AND EASTERN GREAT LAKES FOR THE FIRST HALF OF
NEXT WEEK WITH DRY WEATHER AND WARMING TEMPERATURES. THE JANUARY
THAW WILL LAST RIGHT THROUGH NEXT WEEKEND WITH MILD TEMPERATURES AND
INCREASING CHANCES OF RAIN.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WIDESPREAD AREA OF MAINLY LIGHT WET SNOW HAS BLOSSOMED ACROSS ALL
OF WESTERN NY THIS MORNING...MIXED WITH RAIN ALONG THE LAKESHORES
AND NIAGARA COUNTY. THIS APPEARS TO BE TIED TO WEAK ASCENT JUST
AHEAD OF A WEAK SHORTWAVE APPARENT IN WATER VAPOR IMAGERY CROSSING
CENTRAL LAKE ERIE THIS MORNING. MODEL GUIDANCE IS NOT CAPTURING THIS
AT ALL...SO HAVE UPDATED THE GRIDS BASED SOLELY ON EXTRAPOLATION OF
CURRENT RADAR TRENDS FOR THE NEXT 6 HOURS OR SO. EXPECT STEADY LIGHT
SNOW ACROSS WESTERN NY THROUGH AT LEAST EARLY AFTERNOON. AT LOWER
ELEVATIONS TEMPERATURES ARE ALREADY ABOVE FREEZING...SO JUST EXPECT
LESS THAN AN INCH OF ACCUMULATION ON EXISTING SNOW...WITH ROADS JUST
REMAINING WET. SOME RAIN WILL ALSO MIX IN AT LOWER ELEVATIONS. THE
HIGHER TERRAIN OF THE SOUTHERN TIER MAY PICK UP AN INCH OR SO TODAY
AS TEMPERATURES REMAIN CLOSER TO THE FREEZING MARK.
IT APPEARS THIS AREA OF WET SNOW WILL STRUGGLE TO MOVE EAST...WITH
JUST A FEW BRIEF SNOW OR RAIN SHOWERS FROM THE GENESEE VALLEY INTO
CENTRAL NY THIS AFTERNOON. EAST OF LAKE ONTARIO EXPECT A SIMILAR
BLOSSOMING OF LIGHT SNOW BY EARLY AFTERNOON AS THE SHORTWAVE MOVES
EAST AND INTERACTS WITH AN OLD FRONTAL BOUNDARY STILL IN THE
VICINITY. EXPECT AROUND AN INCH THERE THIS AFTERNOON...WITH UP TO 2
INCHES ACROSS THE TUG HILL AND WESTERN FOOTHILLS OF THE ADIRONDACKS.
THE NEXT PART OF THIS GENERALLY WEAK SYSTEM WILL IMPACT THE REGION
DURING THE LATE AFTERNOON AND EVENING HOURS. THE KEY WILL BE THE
PASSAGE OF ANOTHER SHORT WAVE...WHICH WILL HELP DRIVE A COLD FRONT
ACROSS THE REGION. HOWEVER...THERE WILL BE WELL ALIGNED SOUTHWEST
FLOW AHEAD OF THIS...WITH AMPLE MOISTURE AND A LONG FETCH. 850 MB
TEMPERATURES WILL ONLY BE AROUND -7C...WITH LAKE INDUCED CAPES
BARELY MEASURABLE. HOWEVER...THIS WILL PROBABLY BE ENOUGH TO BOOST
MOISTURE A BIT...AND BRING A PERIOD OF SNOW TO MOST LOCATIONS. THE
QPF FORECAST OF MOST OF THE HIGHER RESOLUTION MODEL GUIDANCE
SUGGESTS THIS ENHANCEMENT WILL BE A SIGNIFICANT PART OF WHATEVER
SNOW FALLS...AND SEVERAL RUNS OF THE HRRR ARE PRODUCING PLAUSIBLE
SOLUTIONS.
THE LIONS SHARE OF SNOW WILL FALL BETWEEN 21Z AND 06Z...WITH MOST
LOCATIONS LIKELY TO SEE ONLY A FEW HOURS OF LIGHT TO MODERATE
SNOWS SOMEWHERE IN THAT TIMEFRAME. EXPECT AN INCH OR TWO TO FALL EAST
OF LAKE ERIE...MAINLY ACROSS THE HIGHER TERRAIN WITH AN ADDED BOOST
FROM UPSLOPE FLOW. STEADIER SNOWS WILL FALL EAST OF LAKE
ONTARIO...WITH STEADIER SNOWS LIKELY TO DEVELOP THIS AFTERNOON...AND
CONTINUE INTO THE EVENING. HRRR GUIDANCE SUGGESTS A BAND OF MODERATE
SNOW WILL DEVELOP...WITH A TOTAL OF 2 TO 4 INCHES OF SNOW LIKELY IN
THAT REGION THIS AFTERNOON AND EVENING. THIS IS IN LINE WITH THE
SEVERAL RUNS OF THE RGEM/NAM. ONE LIMITING FACTOR MAY BE
TEMPERATURES...WHICH WILL BE NEAR OR ABOVE FREEZING THROUGH THE
EVENT AT LOWER ELEVATIONS...WHICH MAY TEMPER ACCUMULATIONS NEAR LAKE
ONTARIO. THE LEAST AMOUNT OF SNOW WILL FALL FROM THE SOUTH SHORE OF
LAKE ONTARIO INTO THE FINGER LAKES...WHERE THE LEAST PRECIP AND
WARMEST BOUNDARY LAYER TEMPERATURES WILL BE FOUND. SOME OF THESE
AREAS MAY SEE NO ACCUMULATION AT ALL.
THE FRONT WILL PUSH SOUTH OF THE REGION LATE TONIGHT...WHICH SHOULD
BRING DRIER AIR INTO THE REGION. SOME LIGHT LAKE EFFECT SNOW SHOWERS
OR FLURRIES CAN/T BE RULED OUT...BUT WHAT DOES DEVELOP SHOULD BE
SHORT LIVED GIVEN THE SHORT FETCH IN THE NORTHERLY FLOW AND THE DRY
AIR UPSTREAM. HOWEVER...THIS SET UP IS FAVORABLE FOR CLOUDS TO BE
QUITE PERSISTENT BEHIND THE FRONT...AS ANY LAKE MOISTURE GETS
TRAPPED BENEATH THE INVERSION. BECAUSE OF THIS...HEDGE ON THE WARM
SIDE OF GUIDANCE FOR LOW TEMPERATURES. EXPECT LOWS IN THE LOWER 20S
IN MOST LOCATIONS...BUT SIGNIFICANTLY COOLER TEMPERATURES ARE
POSSIBLE EAST OF LAKE ONTARIO WHERE CLEARING IS POSSIBLE.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
A QUIET PERIOD IS EXPECTED MONDAY AND TUESDAY WITH A SLOW MODERATING
TREND TO CONTINUE THROUGH THE WORK WEEK.
FOR MONDAY A FEW FLURRIES OR LIGHT SNOW SHOWERS MAY STILL BE FALLING
OFF LAKE ONTARIO SOUTHEAST OF THE LAKE EARLY IN THE MORNING HOURS.
TEMPERATURES ALOFT AT 850 HPA UNDER WARM AIR ADVECTION ARE ONLY
MARGINAL FOR LAKE EFFECT SNOW...AND WITH LOW LEVEL LIFT ESSENTIALLY
GONE AND MOISTURE LACKING FROM WITHIN THE SNOW GROWTH ZONE...ANY
SUPPORT FOR LAKE EFFECT SNOW WILL NOT BE CONDUCIVE...THUS ANY LAKE
ACTIVITY SHOULD DIMINISH QUICKLY THROUGH THE MORNING. THE 850 HPA
RIDGE REMAINS TO OUR WEST TO START THE DAY AND A BROKEN LOW LAYER OF
CLOUDS ACROSS HIGHER TERRAIN OF WNY...GENESEE VALLEY AND NORTHERN
FINGER LAKES REGION WILL LIKELY START THE DAY. AS THIS RIDGE AXIS
PASSES THE AREA FROM WEST TO EAST THROUGH THE MORNING HOURS EXPECT
INCREASING AMOUNTS OF SUNSHINE. DESPITE A GOOD DEAL OF SUNSHINE
THROUGH THE AFTERNOON HOURS TEMPERATURES WILL HOLD TO AROUND NORMAL
ACROSS WESTERN NEW YORK...WITH HIGHS AROUND 30...AND SLIGHTLY BELOW
NORMAL ACROSS THE EASTERN LAKE ONTARIO REGION WITH LOW TO MID
20S.
MONDAY NIGHT A BROAD AREA OF HIGH PRESSURE WILL BE FOUND ALONG THE
ATLANTIC COASTLINE WITH A SOUTHWEST RETURN FLOW ACROSS THE EASTERN
GREAT LAKES REGION. THIS WILL PROHIBIT TEMPERATURES FROM
PLUNGING...AND IN FACT THEY MAY RISE A DEGREE OR TWO OVERNIGHT
ACROSS THE DOWN SLOPE AREAS OF WNY. TOWARDS THE NORTHERN FINGER
LAKES AND EASTERN LAKE ONTARIO REGION WHERE THE SOUTHWEST FLOW WILL
NOT BE AS GREAT TEMPERATURES WILL FALL BACK INTO THE TEENS TO AROUND
20. TO THE WEST MILDER OVERNIGHT LOWS ARE EXPECTED...WITH LOW 20S
ACROSS INTERIOR SOUTHWEST NEW YORK AND UPPER 20S FOR THE LOWER
ELEVATIONS.
LATE MONDAY NIGHT AND TUESDAY A STORM SYSTEM WILL PASS WELL TO OUR
NORTH ACROSS JAMES BAY AND CENTRAL/NORTHERN QUEBEC. A TIGHTENING
PRESSURE GRADIENT BETWEEN THIS SYSTEM AND HIGH PRESSURE ALONG THE
EASTERN SHORELINE WILL ALLOW WINDS TO BECOME BREEZY THROUGH THE DAY
TUESDAY...ESPECIALLY OFF THE LAKES ON A SOUTHWEST FLOW. A FEW CLOUDS
WILL LIKELY PASS ACROSS THE REGION THOUGH STILL A GOOD DEAL OF
SUNSHINE IS EXPECTED. TEMPERATURES ALOFT AT 850 HPA WILL BE SEVERAL
DEGREES WARMER THAN MONDAY...AND WITH THESE SOUTHWEST WINDS
TEMPERATURES SHOULD BE A BIT WARMER THAN MONDAY...WITH HIGHS
MODERATING INTO THE MID TO UPPER 30S. REMAINING DRY OVERNIGHT THOUGH
CLOUDS WILL START TO THICKEN MORE AS A SECOND STORM SYSTEM TAKES A
SLIGHTLY MORE SOUTHERN TRACK THROUGH CANADA. LOWS TUESDAY NIGHT WILL
FALL BACK INTO THE MID 20S TO AROUND 30 ACROSS THE REGION.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A GENERAL ZONAL FLOW WILL REMAIN IN PLACE ALONG THE CANADIAN/U.S.
BORDER THROUGH THURSDAY. AFTER THAT...A MORE AMPLIFIED FLOW WILL SET
UP THURSDAY NIGHT THROUGH SATURDAY AS A DEEPENING TROUGH DIGS INTO
THE WESTERN U.S...WHILE A FLAT RIDGE REMAINS IN PLACE OVER EASTERN
THIRD OF THE NATION.
REGARDING THE FORECAST DETAILS...A WELL DEFINED SHORT WAVE WILL
PASS JUST NORTH OF NEW YORK STATE ON WEDNESDAY...BEFORE DRIFTING
INTO NORTHERN NEW ENGLAND WEDNESDAY NIGHT. A TIGHT PRESSURE GRADIENT
BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEAST WILL AGAIN
MAKE FOR A BREEZY TO WINDY DAY ACROSS THE REGION. EXPECT WIND GUSTS
TO BE STRONGER WEDNESDAY THAN TUESDAY...WITH THE LOW CLOSER TO THE
REGION. A FEW GUSTS MAY APPROACH 40 TO 45 MPH IN TRADITIONALLY GUSTY
AREAS OF THE CWA.
A WEAK FRONT THAT IS ASSOCIATED WITH THIS IMPULSE WILL DROP SOUTH
ACROSS NEW YORK STATE WEDNESDAY NIGHT...BUT THE FRONT WILL NOT HAVE
MUCH MOISTURE TO WORK WITH. WILL HAVE LOW CHC POPS EAST OF LAKE
ONTARIO WHERE SOME LAKE ENHANCEMENT TO THE PRECIPITATION MIGHT
OCCUR. OTHERWISE EXPECT THE REGION TO REMAIN DRY.
ON THURSDAY...THE GFS AND ECMWF ARE IN BETTER AGREEMENT REGARDING
THE MOVEMENT OF THE CLOSED LOW THAT WILL BE LIFTING OUT OF THE
SOUTHERN PLAINS. THE GFS IS STILL A LITTLE FASTER IN LIFTING THE
UPPER LOW OUT...BUT THE GENERAL TREND IS THAT ANY PCPN ASSOCIATED
WITH THE APPROACHING LOW MAY DELAYED UNTIL THURSDAY NIGHT. THE
SLOWER MOVEMENT OF THE LOW ALSO MEANS THAT IT WILL TAKE LONGER THE
FOR BOUNDARY LAYER TEMPERATURES TO MODERATE. THIS MAY RESULT IN A
BETTER CHANCE FOR LIGHT SNOW AT THE ONSET OF THE PCPN.
ON FRIDAY...THE UPPER LOW WILL WEAKEN AS IT ENCOUNTERS THE FLAT
RIDGE THAT WILL STILL BE IN PLACE OVER THE EASTERN PART OF THE
NATION. BY SATURDAY...THE ECMWF TAKES THE ASSOCIATED SURFACE LOW AND
MERGES IT WITH A DEEPER LOW THAT WILL BE LIFTING NORTH ACROSS JAMES
BAY. SINCE THE SURFACE LOW IS FORECAST TO STAY TO OUR WEST...A MILD
SOUTHWEST FLOW WILL PREVAIL ACROSS THE AREA. THIS WILL LIKELY CAUSE
MOST PCPN TO FALL AS RAIN ON FRIDAY AND SATURDAY.
THE MODERATING TREND DURING THIS PERIOD WILL PUSH TEMPERATURES INTO
THE LOWER TO MID 40S ACROSS MOST OF THE AREA ON FRIDAY AND SATURDAY.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
EXPECT MAINLY MVFR CONDITIONS ACROSS WESTERN NY WITH WIDESPREAD
LIGHT/WET SNOW MIXED WITH RAIN AT TIMES. THERE MAY BE A FEW BRIEF
PERIODS OF IFR IN THE SOMEWHAT STEADIER SNOW. MVFR CIGS HAVE ALSO
SPREAD INTO MUCH OF THE AREA...AND THESE WILL CONTINUE THIS
AFTERNOON.
AFTER THIS...A FRONTAL BOUNDARY AND UPPER LEVEL TROF WILL BRING A
PERIOD OF SNOW TO MOST TAF LOCATIONS...WITH THIS LIKELY TO RESULT
VSBY OF 2SM OR LOWER...AND IFR CONDITIONS. THE LOWEST CONDITIONS
WILL BE AT JHW/ART...WITH LIGHTER SNOWFALL RATES EXPECTED AT
IAG/ROC. CONFIDENCE IN TIMING IS MODERATE...GIVEN GOOD MODEL
AGREEMENT IN THE PATTERN...HOWEVER IT IS POSSIBLE IFR CIGS MAY
BUILD IN AHEAD OF THE SNOW IN THE SOUTHWEST FLOW.
CIGS SHOULD MAINLY LIFT BEHIND THE FRONT...BUT MAY BRIEFLY LOWER
IMMEDIATELY PRECEDING THE FRONTAL PASSAGE DURING THE EVENING
HOURS. AFTER THIS...CLOUDS WILL PROBABLY SCATTER NEAR THE
LAKES...BUT PERSISTENT MVFR CIGS ARE MORE LIKELY INLAND.
OUTLOOK...
MONDAY AND TUESDAY...VFR.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS.
&&
.MARINE...
LOW PRESSURE ACROSS THE CENTRAL LAKES WILL LIFT UP THE SAINT
LAWRENCE VALLEY LATER TODAY. THIS WILL RESULT IN A DECENT SOUTHWEST
FLOW AND SMALL CRAFT CONDITIONS TODAY AND INTO TONIGHT. WINDS WILL
SHIFT TO THE NORTH AS AN ASSOCIATED COLD FRONT DROPS ACROSS THE
WATERS TONIGHT. THEN HIGH PRESSURE WILL BUILD ACROSS THE WATERS
MONDAY...WITH DIMINISHING WINDS. AS THE HIGH SLIDES EAST...A
TIGHTENING PRESSURE GRADIENT MAY REQUIRE SMALL CRAFT ADVISORIES
AGAIN MID-WEEK IN A SOUTHWESTERLY FLOW.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LEZ040-041.
SMALL CRAFT ADVISORY UNTIL 9 PM EST THIS EVENING FOR
LEZ020.
SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL/HITCHCOCK
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
741 AM EST SUN JAN 6 2013
.SYNOPSIS...
A WEAK AREA OF LOW PRESSURE WILL BRING MINOR SNOW ACCUMULATIONS TO
MOST LOCATIONS THIS AFTERNOON AND EVENING...BUT SNOWS WILL BE
A BIT STEADIER EAST OF LAKE ONTARIO. HIGH PRESSURE WILL THEN BUILD
INTO THE OHIO VALLEY AND EASTERN GREAT LAKES FOR THE FIRST HALF OF
NEXT WEEK WITH DRY WEATHER AND WARMING TEMPERATURES. THE JANUARY
THAW WILL LAST RIGHT THROUGH NEXT WEEKEND WITH MILD TEMPERATURES AND
INCREASING CHANCES OF RAIN.
&&
.NEAR TERM /THROUGH TONIGHT/...
A SHORTWAVE EXITING TO THE EAST HAS LEFT WESTERN NEW YORK IN NO
MANS LAND OF SORT. THERE ARE SOME LIGHT LAKE ENHANCED RAIN AND
SNOW SHOWERS NORTHEAST OF LAKE ERIE...OTHERWISE THE MAJORITY OF
THE REGION IS DRY. THIS PATTERN SHOULD CONTINUE THROUGH THE
MORNING HOURS. THE FINGER LAKES AND GENESEE VALLEY MAY GET SOME
BREAKS OF SUN...WHICH WOULD HELP TEMPERATURES WARM A BIT. EXPECT
HIGHS IN THE UPPER 30S IN MOST LOCATIONS...WITH LOWER 40S IN SPOTS
WHICH GET SOME SUN.
THE MORE SIGNIFICANT PART OF THIS GENERALLY WEAK SYSTEM WILL IMPACT
THE REGION DURING THE AFTERNOON AND EVENING HOURS. THE KEY WILL
BE THE PASSAGE OF A SHORT WAVE...WHICH WILL HELP DRIVE A COLD
FRONT ACROSS THE REGION. HOWEVER...THERE WILL BE WELL ALIGNED
SOUTHWEST FLOW AHEAD OF THIS...WITH AMPLE MOISTURE AND A LONG
FETCH. 850 MB TEMPERATURES WILL ONLY BE AROUND -7C...WITH LAKE
INDUCED CAPES BARELY MEASURABLE. HOWEVER...THIS WILL PROBABLY BE
ENOUGH TO BOOST MOISTURE A BIT...AND BRING A PERIOD OF SNOW TO
MOST LOCATIONS. THE QPF FORECAST OF MOST OF THE HIGHER RESOLUTION
MODEL GUIDANCE SUGGESTS THIS ENHANCEMENT WILL BE A SIGNIFICANT
PART OF WHATEVER SNOW FALLS...AND SEVERAL RUNS OF THE HRRR ARE
PRODUCING PLAUSIBLE SOLUTIONS.
THE LIONS SHARE OF SNOW WILL FALL BETWEEN 18Z AND 06Z...WITH MOST
LOCATIONS LIKELY TO SEE ONLY A FEW HOURS OF LIGHT TO MODERATE
SNOWS SOMEWHERE IN THAT TIMEFRAME. EXPECT AN INCH OR TWO TO FALL EAST
OF LAKE ERIE. STEADIER SNOWS WILL FALL EAST OF LAKE ONTARIO...WITH
STEADIER SNOWS LIKELY TO DEVELOP THIS AFTERNOON...AND CONTINUE
INTO THE EVENING. HRRR GUIDANCE SUGGESTS A BAND OF MODERATE SNOW
WILL DEVELOP...WITH A TOTAL OF 2 TO 4 INCHES OF SNOW LIKELY IN
THAT REGION THIS AFTERNOON AND EVENING. THIS IS IN LINE WITH THE
SEVERAL RUNS OF THE RGEM/NAM. THE EASTERN LAKE ONTARIO
REGION...WITH THE SOUTHWEST FLOW...AND MODEL QPF FORECASTS
SUGGESTING THIS FORECAST WILL APPLY TO THE CITY OF WATERTOWN AND
ALL OF JEFFERSON COUNTY. WILL HAVE TO WATCH THIS POTENTIAL
BAND...WITH THE POSSIBILITY THAT AN ADVISORY WILL BE REQUIRED. ONE
LIMITING FACTOR MAY BE TEMPERATURES...WHICH WILL BE NEAR OR ABOVE
FREEZING THROUGH THE EVENT. LESSER AMOUNTS WILL FALL FURTHER FROM
THE LAKE IN ROCHESTER...GENESEE VALLEY...AND FINGER LAKES REGIONS.
THE FRONT WILL PUSH SOUTH OF THE REGION LATE TONIGHT...WHICH SHOULD
BRING DRIER AIR INTO THE REGION. SOME LIGHT LAKE EFFECT SNOW SHOWERS
OR FLURRIES CAN/T BE RULED OUT...BUT WHAT DOES DEVELOP SHOULD BE
SHORT LIVED GIVEN THE SHORT FETCH IN THE NORTHERLY FLOW AND THE DRY
AIR UPSTREAM. HOWEVER...THIS SET UP IS FAVORABLE FOR CLOUDS TO BE
QUITE PERSISTENT BEHIND THE FRONT...AS ANY LAKE MOISTURE GETS
TRAPPED BENEATH THE INVERSION. BECAUSE OF THIS...HEDGE ON THE WARM
SIDE OF GUIDANCE FOR LOW TEMPERATURES. EXPECT LOWS IN THE LOWER 20S
IN MOST LOCATIONS...BUT SIGNIFICANTLY COOLER TEMPERATURES ARE
POSSIBLE EAST OF LAKE ONTARIO WHERE CLEARING IS POSSIBLE.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
A QUIET PERIOD IS EXPECTED MONDAY AND TUESDAY WITH A SLOW MODERATING
TREND TO CONTINUE THROUGH THE WORK WEEK.
FOR MONDAY A FEW FLURRIES OR LIGHT SNOW SHOWERS MAY STILL BE FALLING
OFF LAKE ONTARIO SOUTHEAST OF THE LAKE EARLY IN THE MORNING HOURS.
TEMPERATURES ALOFT AT 850 HPA UNDER WARM AIR ADVECTION ARE ONLY
MARGINAL FOR LAKE EFFECT SNOW...AND WITH LOW LEVEL LIFT ESSENTIALLY
GONE AND MOISTURE LACKING FROM WITHIN THE SNOW GROWTH ZONE...ANY
SUPPORT FOR LAKE EFFECT SNOW WILL NOT BE CONDUCIVE...THUS ANY LAKE
ACTIVITY SHOULD DIMINISH QUICKLY THROUGH THE MORNING. THE 850 HPA
RIDGE REMAINS TO OUR WEST TO START THE DAY AND A BROKEN LOW LAYER OF
CLOUDS ACROSS HIGHER TERRAIN OF WNY...GENESEE VALLEY AND NORTHERN
FINGER LAKES REGION WILL LIKELY START THE DAY. AS THIS RIDGE AXIS
PASSES THE AREA FROM WEST TO EAST THROUGH THE MORNING HOURS EXPECT
INCREASING AMOUNTS OF SUNSHINE. DESPITE A GOOD DEAL OF SUNSHINE
THROUGH THE AFTERNOON HOURS TEMPERATURES WILL HOLD TO AROUND NORMAL
ACROSS WESTERN NEW YORK...WITH HIGHS AROUND 30...AND SLIGHTLY BELOW
NORMAL ACROSS THE EASTERN LAKE ONTARIO REGION WITH LOW TO MID
20S.
MONDAY NIGHT A BROAD AREA OF HIGH PRESSURE WILL BE FOUND ALONG THE
ATLANTIC COASTLINE WITH A SOUTHWEST RETURN FLOW ACROSS THE EASTERN
GREAT LAKES REGION. THIS WILL PROHIBIT TEMPERATURES FROM
PLUNGING...AND IN FACT THEY MAY RISE A DEGREE OR TWO OVERNIGHT
ACROSS THE DOWN SLOPE AREAS OF WNY. TOWARDS THE NORTHERN FINGER
LAKES AND EASTERN LAKE ONTARIO REGION WHERE THE SOUTHWEST FLOW WILL
NOT BE AS GREAT TEMPERATURES WILL FALL BACK INTO THE TEENS TO AROUND
20. TO THE WEST MILDER OVERNIGHT LOWS ARE EXPECTED...WITH LOW 20S
ACROSS INTERIOR SOUTHWEST NEW YORK AND UPPER 20S FOR THE LOWER
ELEVATIONS.
LATE MONDAY NIGHT AND TUESDAY A STORM SYSTEM WILL PASS WELL TO OUR
NORTH ACROSS JAMES BAY AND CENTRAL/NORTHERN QUEBEC. A TIGHTENING
PRESSURE GRADIENT BETWEEN THIS SYSTEM AND HIGH PRESSURE ALONG THE
EASTERN SHORELINE WILL ALLOW WINDS TO BECOME BREEZY THROUGH THE DAY
TUESDAY...ESPECIALLY OFF THE LAKES ON A SOUTHWEST FLOW. A FEW CLOUDS
WILL LIKELY PASS ACROSS THE REGION THOUGH STILL A GOOD DEAL OF
SUNSHINE IS EXPECTED. TEMPERATURES ALOFT AT 850 HPA WILL BE SEVERAL
DEGREES WARMER THAN MONDAY...AND WITH THESE SOUTHWEST WINDS
TEMPERATURES SHOULD BE A BIT WARMER THAN MONDAY...WITH HIGHS
MODERATING INTO THE MID TO UPPER 30S. REMAINING DRY OVERNIGHT THOUGH
CLOUDS WILL START TO THICKEN MORE AS A SECOND STORM SYSTEM TAKES A
SLIGHTLY MORE SOUTHERN TRACK THROUGH CANADA. LOWS TUESDAY NIGHT WILL
FALL BACK INTO THE MID 20S TO AROUND 30 ACROSS THE REGION.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A GENERAL ZONAL FLOW WILL REMAIN IN PLACE ALONG THE CANADIAN/U.S.
BORDER THROUGH THURSDAY. AFTER THAT...A MORE AMPLIFIED FLOW WILL SET
UP THURSDAY NIGHT THROUGH SATURDAY AS A DEEPENING TROUGH DIGS INTO
THE WESTERN U.S...WHILE A FLAT RIDGE REMAINS IN PLACE OVER EASTERN
THIRD OF THE NATION.
REGARDING THE FORECAST DETAILS...A WELL DEFINED SHORT WAVE WILL
PASS JUST NORTH OF NEW YORK STATE ON WEDNESDAY...BEFORE DRIFTING
INTO NORTHERN NEW ENGLAND WEDNESDAY NIGHT. A TIGHT PRESSURE GRADIENT
BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEAST WILL AGAIN
MAKE FOR A BREEZY TO WINDY DAY ACROSS THE REGION. EXPECT WIND GUSTS
TO BE STRONGER WEDNESDAY THAN TUESDAY...WITH THE LOW CLOSER TO THE
REGION. A FEW GUSTS MAY APPROACH 40 TO 45 MPH IN TRADITIONALLY GUSTY
AREAS OF THE CWA.
A WEAK FRONT THAT IS ASSOCIATED WITH THIS IMPULSE WILL DROP SOUTH
ACROSS NEW YORK STATE WEDNESDAY NIGHT...BUT THE FRONT WILL NOT HAVE
MUCH MOISTURE TO WORK WITH. WILL HAVE LOW CHC POPS EAST OF LAKE
ONTARIO WHERE SOME LAKE ENHANCEMENT TO THE PRECIPITATION MIGHT
OCCUR. OTHERWISE EXPECT THE REGION TO REMAIN DRY.
ON THURSDAY...THE GFS AND ECMWF ARE IN BETTER AGREEMENT REGARDING
THE MOVEMENT OF THE CLOSED LOW THAT WILL BE LIFTING OUT OF THE
SOUTHERN PLAINS. THE GFS IS STILL A LITTLE FASTER IN LIFTING THE
UPPER LOW OUT...BUT THE GENERAL TREND IS THAT ANY PCPN ASSOCIATED
WITH THE APPROACHING LOW MAY DELAYED UNTIL THURSDAY NIGHT. THE
SLOWER MOVEMENT OF THE LOW ALSO MEANS THAT IT WILL TAKE LONGER THE
FOR BOUNDARY LAYER TEMPERATURES TO MODERATE. THIS MAY RESULT IN A
BETTER CHANCE FOR LIGHT SNOW AT THE ONSET OF THE PCPN.
ON FRIDAY...THE UPPER LOW WILL WEAKEN AS IT ENCOUNTERS THE FLAT
RIDGE THAT WILL STILL BE IN PLACE OVER THE EASTERN PART OF THE
NATION. BY SATURDAY...THE ECMWF TAKES THE ASSOCIATED SURFACE LOW AND
MERGES IT WITH A DEEPER LOW THAT WILL BE LIFTING NORTH ACROSS JAMES
BAY. SINCE THE SURFACE LOW IS FORECAST TO STAY TO OUR WEST...A MILD
SOUTHWEST FLOW WILL PREVAIL ACROSS THE AREA. THIS WILL LIKELY CAUSE
MOST PCPN TO FALL AS RAIN ON FRIDAY AND SATURDAY.
THE MODERATING TREND DURING THIS PERIOD WILL PUSH TEMPERATURES INTO
THE LOWER TO MID 40S ACROSS MOST OF THE AREA ON FRIDAY AND SATURDAY.
&&
.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
EXPECT MAINLY MVFR CONDITIONS DUE TO CEILINGS THROUGH THIS MORNING
AS AN INITIAL DISTURBANCE EXITS TO THE EAST. BRIEF BREAKS TO VFR
ARE POSSIBLE...IN AND OUT OF SUBTLE WAVES OF MOISTURE.
AFTER THIS...A FRONTAL BOUNDARY AND UPPER LEVEL TROF WILL BRING A
PERIOD OF SNOW TO MOST TAF LOCATIONS...WITH THIS LIKELY TO RESULT
VSBY OF 2SM OR LOWER...AND IFR CONDITIONS. THE LOWEST CONDITIONS
WILL BE AT JHW/ART...WITH LIGHTER SNOWFALL RATES EXPECTED AT
IAG/ROC. CONFIDENCE IN TIMING IS MODERATE...GIVEN GOOD MODEL
AGREEMENT IN THE PATTERN...HOWEVER IT IS POSSIBLE IFR CIGS MAY
BUILD IN AHEAD OF THE SNOW IN THE SOUTHWEST FLOW.
CIGS SHOULD MAINLY LIFT BEHIND THE FRONT...BUT MAY BRIEFLY LOWER
IMMEDIATELY PRECEDING THE FRONTAL PASSAGE DURING THE EVENING
HOURS. AFTER THIS...CLOUDS WILL PROBABLY SCATTER NEAR THE
LAKES...BUT PERSISTENT MVFR CIGS ARE MORE LIKELY INLAND.
OUTLOOK...
MONDAY AND TUESDAY...VFR.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS.
&&
.MARINE...
LOW PRESSURE ACROSS THE CENTRAL LAKES WILL LIFT UP THE SAINT
LAWRENCE VALLEY LATER TODAY. THIS WILL RESULT IN A DECENT SOUTHWEST
FLOW AND SMALL CRAFT CONDITIONS TODAY AND INTO TONIGHT. WINDS WILL
SHIFT TO THE NORTH AS AN ASSOCIATED COLD FRONT DROPS ACROSS THE
WATERS TONIGHT. THEN HIGH PRESSURE WILL BUILD ACROSS THE WATERS
MONDAY...WITH DIMINISHING WINDS. AS THE HIGH SLIDES EAST...A
TIGHTENING PRESSURE GRADIENT MAY REQUIRE SMALL CRAFT ADVISORIES
AGAIN MID-WEEK IN A SOUTHWESTERLY FLOW.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LEZ040-041.
SMALL CRAFT ADVISORY UNTIL 9 PM EST THIS EVENING FOR
LEZ020.
SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1048 PM EST MON JAN 7 2013
.SYNOPSIS...
CLOUDS WILL INCREASE TONIGHT IN ASSOCIATED WITH A COASTAL TROUGH.
IT WILL REMAIN FAIRLY CLOUDY THROUGH THE MIDWEEK ALTHOUGH
TEMPERATURES WILL BE ON THE INCREASE ESPECIALLY AS A WARM FRONT
LIFTS THROUGH THURSDAY. WARM AND RAIN FREE WEATHER WILL LAST
THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 1035 PM MONDAY...MID TO HIGH LEVEL CLOUDS CONTINUE TO EXPAND
NORTHWARD ACROSS THE FA THIS EVENING AND OVERNIGHT...WITH A LOW
DECK POSSIBLE ALONG THE IMMEDIATE COAST AS LATEST HRRR MODEL
INDICATES AN INVERTED SFC TROF TO DEVELOP JUST OFFSHORE LATE
TONIGHT. OVERNIGHT TEMPS/DEWPOINTS CONTINUE TO BE MASSAGED...MOSTLY
TOWARD THE UPWARD SIDE DUE TO INCREASING OPAQUE SKY COVER. WINDS
ACROSS THE INLAND COUNTIES WILL HAVE THE POTENTIAL TO DECOUPLE AS
THE CENTER OF THE SFC HIGH EXTENDS ACROSS THIS AREA. COULD OBSERVE
NEAR FREEZING READINGS IF RAD COOLING CONDITIONS PERSIST
THROUGH THE OVERNIGHT.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...AS WEDGE OF HIGH PRESSURE HANGS ON AT THE
SURFACE IN A WEDGE-LIKE SCENARIO THE MAIN FORECAST ISSUE ON TUES
SEEMS TO BE THE EXTENT OF CLOUD COVER THAT MANAGES TO DEVELOP. E TO
NE WINDS BENEATH WARM ADVECTION/SW FLOW AT 850 MB LEADS TO A NEARLY
ISOTHERMAL LAYER FROM VERY ROUGHLY 950-850MB WITH FAIRLY HIGH RH.
ABOVE THIS LAYER IS VERY DRY AIR ASSOCIATED WITH SUBSIDENCE
INVERSION. ACTUAL MIXING IS FORECAST TO BE QUITE SHALLOW SO THIS DRY
AIR MAY NOT COME TO BEAR TOO MUCH WITH RESPECT TO CLOUD COVER
OBSERVED AT THE SURFACE...I JUST WONDER IF GUIDANCE IS BRINGING IN
TOO MUCH MOISTURE OFF OF THE ATLANTIC. THE ACTUAL FRONTAL BAND
SHOULD NOT MAKE IT THIS FAR NORTH AND WEST AND GUIDANCE IS IN
FAIRLY GOOD AGREEMENT THAT LOW LEVEL ISENTROPIC UPGLIDE IS VERY
SLOW OR EVEN NOT FORECAST TO DEVELOP UNTIL NIGHTTIME. SHOW A GRADUAL
UPWARD TREND IN SKY COVER BUT WILL CAP VALUES NEAR UPPER RANGES OF
PARTLY CLOUDY SAVE FOR SOUTHERN ZONES WHICH WILL REGISTER MOSTLY
CLOUDY IN TEXT PRODUCTS IN ALL LIKELIHOOD. SMALL POPS HINTED AT IN
GUIDANCE SEEMS IMPLAUSIBLE DUE TO AFOREMENTIONED DRY AIR. DRIZZLE
SEEMS LIKE WORST CASE. BY WEDNESDAY THE HIGH SHOWS VERY LITTLE
MOVEMENT BUT WEAKENS SUFFICIENTLY TO NO LONGER IMPLY COOL AIR
WEDGING. MIXING IS FORECAST TO REMAIN QUITE SHALLOW AND SO SOME OF
THE LOW LEVEL WARM AIR ADVECTION MAY NOT BE REALIZED AT THE SURFACE
(ESPECIALLY IF THE CLOUD COVER CONTINUES TO INCREASE). BASED UPON
THIS AND SIMILAR CONCERN NOTED BY SOME NEIGHBORS HAVE TRIMMED WED
HIGHS A FEW DEGREES BELOW GUIDANCE. MOISTURE PROFILE A LITTLE DEEPER
IN FORECAST SOUNDINGS BUT RAIN CHANCES WILL STAY CAPPED AT SLIGHT
CHANCE IN THE ABSENCE OF ANY REAL FORCING MECHANISM.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...MAIN DETAILS OF THE SYNOPTIC PATTERN FOR THE
EXTENDED REMAIN IN PLACE THIS AFTERNOON AS A STRONG CLOSED LOW
WILL MOVE QUICKLY THROUGH THE MIDWEST AND SHEAR OUT. THE FLOW
BETWEEN THIS FEATURE AND AN ANOMALOUS RIDGE TO THE SOUTHEAST WILL
CREATE A VERY WARM AND PERSISTENT FLOW.
THE LOW...BEFORE SHEARING OUT AND FILLING IS 3-4 STAND DEVIATIONS
BELOW NORMAL AND THE RIDGE IS 1-2 ABOVE. 850MB TEMPERATURES OF 13-15
DEGREES C WILL ADVECT INTO THE AREA FOR THE WEEKEND. MEX GUIDANCE IS
ADVERTISING WIDESPREAD 70S FOR THE THIRD DAY IN A ROW AND THE
FORECAST HAS BEEN ADJUSTED UPWARD AS EVEN THE COOLER HPC NUMBERS ARE
MOSTLY IN THE 70S FOR THE WEEKEND. THE ONLY RECORD THAT APPEARS IN
JEOPARDY AT THIS TIME IS FLORENCE FOR SATURDAY WHICH IS 73 DEGREES.
THE KICKER SYSTEM...THE ONE THAT FORCES THE INITIAL DEEP LOW TO MOVE
OUT BEGINS TO IMPACT THE REGION MONDAY WITH INCREASED CLOUDINESS AND
SLIGHT CHANCE POPS HENCE...SLIGHTLY COOLER TEMPERATURES.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
AS OF 00Z...INCREASING HIGH CLOUDS TO THE SOUTH COULD GIVE US SOME
BROKEN CONDITIONS TONIGHT...ESPECIALLY OVER THE SOUTHERN TERMINALS.
A WEAK COASTAL TROUGH TRIES TO DEVELOP TONIGHT. THIS COULD BRING
SOME POSSIBLE MVFR STRATA CU ALONG THE COAST...BUT WILL KEEP IT
SCATTERED FOR THE PRESENT TIME. TUESDAY...RETURN FLOW AROUND HIGH
PRESSURE CENTERED OFFSHORE WILL GIVE US MAINLY LIGHT EASTERLY FLOW.
MODERATE CHANCE OF A VFR STRATA CU CEILING DEVELOPING AROUND MID
MORNING...POSSIBLY CONTINUING THROUGH THE END OF THE FORECAST PERIOD.
EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS/VSBYS WEDNESDAY ASSOCIATED
WITH A COASTAL TROUGH. SLIGHT CHANCE OF SHOWERS WEDNESDAY AND
THURSDAY. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1035 PM MONDAY...CENTER OF SFC HIGH TO SLIDE OFFSHORE FROM
THE MID-ATLANTIC STATES OVERNIGHT INTO TUESDAY...BUT WILL CONTINUE
TO RIDGE BACK ACROSS THE AREA WATERS. INVERTED SFC TROF TO DEVELOP
OFFSHORE AND PARALLEL TO THE CAROLINA COASTLINES TONIGHT AND
PERSIST INTO TUESDAY. LOOK FOR WINDS TO BACK FROM AN ENE DIRECTION
TO NE...WITH WIND SPEEDS BASICALLY AROUND 15 KT...EXCEPT UP TO 20
KT OUTER WATERS OFF CAPE FEAR. SIGNIFICANT SEAS WILL RANGE FROM 2
TO 4 FT...EXCEPT UP TO 5 FT OUTER WATERS OFF CAPE FEAR...AND OUTER
WATERS OFF THE MOUTH OF WINYAH BAY. SIGNIFICANT SEAS WILL
PRIMARILY CONSIST OF WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS.
SHORT TERM/TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY
...WEDGE-LIKE HIGH PRESSURE IN PLACE ON TUESDAY TO BRING A LIGHT
NE FLOW...GENERALLY IN THE 10 TO 15 KT RANGE. SEAS 2 TO 3 FT IN A
PREDOMINANT 5 SECOND WIND CHOP. ON WEDNESDAY THE HIGH BOTH WEAKENS
AND MOVES EVER SO SLIGHTLY TO THE N. WINDS MAY VEER TO EASTERLY
WHILE THEY DROP TO ABOUT 10 KT. THIS WILL CUT OUT THE 3 FT SEAS
AND MOST PLACES WILL BE CAPPED AT 2 FT. DOMINANT PERIOD LIKELY
STAYS ABOUT 5 OR 6 SECONDS BUT A VERY SMALL 10 SECOND EASTERLY
SWELL IS ALSO FORECAST.
LONG TERM/THURSDAY THROUGH FRIDAY/... AS OF 3 PM MONDAY...MAIN
EVENT FOR THE MARINE COMMUNITY WILL BE THE WIND SHIFT OCCURRING
FRIDAY MORNING AS A WARM FRONT MOVES ACROSS. CONFIDENCE IS NOT ALL
THAT GREAT AT LEAST IN REGARDS TO TIMING AS MEDIUM RANGE GUIDANCE
HAS BEEN JUMPING AROUND SOMEWHAT. EXPECT A GRADUAL VEERING FROM
NORTHEAST THURSDAY AFTERNOON TO SOUTH BY FRIDAY AT 1200 UTC.
SPEEDS REMAIN MARGINAL WITH 10-15 KNOTS. EXPECT MORE WESTERLY
WINDS SATURDAY COURTESY OF A GLANCING SHOT FROM A BACKDOOR FRONT.
SIGNIFICANT SEAS LOOK FAIRLY CONSISTENT WITH THE WAVEWATCH STILL A
BIT ON THE HIGH SIDE. THERE COULD STILL BE A SCEC HEADLINE
ESPECIALLY EARLY BUT THE WIND SHIFT SHOULD PRECLUDE A SMALL CRAFT
ADVISORY WITH 3-5 FEET EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...SHK
AVIATION...DL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EST SUN JAN 6 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE THE MIDDLE ATLANTIC STATES
TODAY...FOLLOWED BY THE PASSAGE OF A DRY COLD FRONT TONIGHT. HIGH
PRESSURE WILL BUILD INTO...AND REMAIN OVER OUR REGION...THROUGH
TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1055 AM SUNDAY...
AN AREA OF OF LIGHT RAIN FALLING FROM CEILINGS IN THE 3-6KFT RANGE
ACROSS THE SOUTHEASTERN HALF OF THE RAH CWA WILL SHIFT EAST DURING
THE NEXT FEW HOURS. THE KGSO RAOB THIS MORNING WAS NOTABLY DRIER AND
WARMER IN THE LOWEST ~5KFT COMPARED TO RECENT NAM/GFS FCST BUFR
SOUNDINGS AND NOTED MULTIPLE LAYERS OF DRYING ALOFT. RECENT VIS SAT
IMAGES HAVE INDICATED SOME EASTWARD ADVANCEMENT OF THE AREA OF
THINNING CLOUDS IN THE FOOTHILLS WHILE THE REMAINDER OF THE RAH CWA
IS BLANKETED IN OVERCAST SKIES.
EXPECT MOSTLY CLOUDY/CLOUDY SKIES TO PERSIST FOR THE REMAINDER OF
THE DAY WITH AREAS OF VERY LIGHT PRECIPITATION ACROSS THE
SOUTHERN/SOUTHEAST TIER. AFTER THE INITIAL AREA OF RAIN OVER THE
AREA WANES FOR A FEW HOURS AROUND/JUST AFTER MIDDAY...ANOTHER AREA
OF PATCHY LIGHT RAIN IS EXPECTED TO DEVELOP ACROSS SC AND SPREAD
INTO THE FAR SOUTHERN PIEDMONT..THE SOUTHERN SANDHILLS AND THE
SOUTHERN COASTAL PLAIN. THIS AREA OF RAIN IS EXPECTED TO BE
GENERATED THROUGH LOW LEVEL MOISTURE ADVECTION AND SHALLOW LIFT WITH
THE GFS AND TO A LESSER EXTENT THE NAM INDICATING SOME LIGHT QPF.
THE HIGH RES CONVECTION ALLOWING MODELS...ESPECIALLY THE HRRR HAVE
BEEN BULLISH ON ANOTHER SURGE OF PRECIPITATION BUT THE PAST RUN OR
TWO HAVE BACKED OFF A BIT. WOULD NOT CATEGORIZE THE DAY AS A WASHOUT
AS QPF VALUES WILL ONLY BE ON THE ORDER OF A FEW HUNDREDTHS OF AN
INCH. TEMPERATURES WILL BE MODULATED A GREAT DEAL BY THE CLOUDS AND
PRECIPITATION WITH HIGHS IN THE LOWER 50S ACROSS THE WEST/NORTHWEST
PARTS OF FORECAST AREA TO THE UPPER 40S/NEAR 50 EAST. -BLAES
TONIGHT: A POTENT NORTHERN STREAM S/W TROUGH AND ASSOCIATED SURFACE
COLD FRONT WILL SWEEP EASTWARD ACROSS CENTRAL NC. A RENEWED AREA OF
MID CLOUDS...AND LINGERING JET CIRRUS MAY ACCOMPANY THE S/W THROUGH
06Z...BUT STRONG SUBSIDENCE AND RAPID CLEARING/DRYING WILL COMMENCE
THEREAFTER. POST-FRONTAL...CAA-DRIVEN LOWS IN THE UPPER 20S TO
LOWER-MIDDLE 30S. -MWS
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
AS OF 320 AM SUNDAY...
MODIFIED CONTINENTAL POLAR HIGH PRESSURE WILL BUILD ACROSS AND
LINGER OVER THE MIDDLE ATLANTIC AND CAROLINAS THIS PERIOD...
ASSOCIATED NORTHEASTERLY FLOW DURING THE DAY...AND NIGHTTIME
CALM...WILL RESULT IN BELOW AVERAGE TEMPERATURES IN THE UPPER 40S TO
AROUND 50 AND UPPER 20S...RESPECTIVELY...THE LATTER OF WHICH SHOULD
OCCUR DESPITE INCREASING CIRRUS OVERNIGHT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 258 AM SUNDAY...
MODEL SOLUTIONS COMING TOGETHER WITH THE TRACK OF THE LOW LATE IN
THE WEEK... MOVING FROM TX ON THURS INTO THE GREAT LAKES FRI. GFS
AND ECMWF STILL SHOWING THE TAIL END OF A NORTHERN STREAM COLD FRONT
ENTERING THE REGION ON THURSDAY... WITH BACKED WINDS BRIEFLY
INDICATED ON FORECAST SOUNDINGS... BEFORE A WARM FRONT SURGES NORTH
ON FRIDAY. THE ASSOCIATED COLD FRONT WILL JUST ENTER THE REGION
OVERNIGHT FRIDAY INTO SATURDAY... BEFORE WASHING OUT. TEMPS WILL BE
HIGHLY DEPENDENT ON THE TIMING AND MOVEMENT OF THESE FRONTAL ZONES
IN THE LATTER PART OF THE WEEK... BUT WILL CONTINUE TO KEEP HIGHS IN
THE 60S... WITH LOWS IN THE 40S. PRECIPITATION DOES NOT APPROACH THE
AREA UNTIL LATER IN THE DAY ON THURSDAY... AND LINGERS THROUGH
FRIDAY.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 650 AM SUNDAY...
PERIODS OF LIGHT RAIN OR SPRINKLES WILL CONTINUE MAINLY EAST OF KRDU
(IE. AT KRWI AND KFAY) THROUGH AROUND SUNSET. A PERIOD OF MVFR
CEILINGS WILL LIKELY ACCOMPANY THE THIS LIGHT PRECIPITATION DURING
THE AFTERNOON...PARTICULARLY AT KFAY. A DRY COLD FRONT AND
ASSOCIATED TRAILING CLEAR SKIES AND SURFACE WIND SHIFT TO
NORTHWESTERLY WILL SWEEP EASTWARD ACROSS CENTRAL NC BETWEEN 03-09Z.
OUTLOOK: RETURN SOUTHWESTERLY FLOW WILL PROMOTE AN INCREASING
LIKELIHOOD OF SUB-VFR CEILINGS AT KFAY TUE AFT...AND ACROSS THE
REMAINDER OF CENTRAL NC TERMINALS TUE NIGHT. SUB-VFR CONDITIONS AND
A CHANCE OF SHOWERS WILL THEN RETURN FOR LATE THU.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...BLAES/MWS
SHORT TERM...MWS
LONG TERM...SEC
AVIATION...MWS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
910 PM CST MON JAN 7 2013
.DISCUSSION...
MAIN CHANGE THIS EVE WAS TO KEEP CLOUDS IN NORTHEAST PART OF THE
FCST AREA IN A BIT LATER. OTHER CHANGES FOR COORDINATION WERE
ALREADY DONE IN WCNTRL MN. OBS/SATELLITE SHOWS MVFR CIGS ALONG AND
EAST OF A WALHALLA TO THIEF RIVER FALLS TO BEMIDJI LINE...WITH
SLOW CLEARING TO THE EAST. LATEST RAP MODEL (01Z) INDICATES CLOUDS
WILL CONTINUE TO SLOWLY CLEAR FROM THE WEST BUT NOT REACHING LAKE
OF THE WOODS AREA TIL ABOUT 09Z. THUS UPDATED SKY COVER WITH THIS
TIMING. OTHERWISE CLEAR UNTIL HIGH CLOUDS MOVE LATE TONIGHT AND
TUESDAY MORNING. INCOMING 00Z NAM IS A BIT SLOWER WITH PRECIP
MOSTLY AN AFTN EVENT IN THE VALLEY INTO NW MN. AMOUNTS STILL LOOK
LIGHT.
&&
.PREV DISCUSSION... /ISSUED 553 PM CST MON JAN 7 2013/
DISCUSSION...
WFO MPX COORDINATE EARLY UPDATE TO INCREASE POPS IN WCNTRL MN
TUESDAY AFTN TO LIKELY. EXPECT A BAND OF LIGHT SNOW TO MOVE THRU
BUT AMOUNTS QUITE LOW IN WCNTRL MN...BUT CONFIDENT SOME LIGHT SNOW
WILL INDEED FALL. SO TO BLEND WITH MPX UPDATE SPREAD 60 POPS
SOUTHEAST INTO WCNTRL MN TUES AFTN. NO OTHER CHANGES.
PREV DISCUSSION... /ISSUED 259 PM CST MON JAN 7 2013/
SHORT TERM...
CHALLENGES FOR THE FORECAST INCLUDE TEMPS THRU THURSDAY AND AREAL
COVERAGE AND AMOUNT OF SNOW WITH PROGRESSIVE SYSTEM ON TUESDAY THEN
WINDS IN WAKE OF AFOREMENTIONED SYSTEM TUESDAY AFTN AND EVENING.
MODELS IN FAIR AGREEMENT WITH THE SHORT TERM AND USED A BLEND FOR
THE PACKAGE.
CURRENTLY WARM WESTERLY WINDS AT SFC UNDER A BROAD SHORT WAVE
TROUGH GIVING 500MB WESTERLY FLOW AS THE LATEST SHORT WAVE AND
ASSOCIATED SFC LOW IN THE PROGRESSIVE WAVE TRAIN HAVE MOVED INTO
W ONTARIO. A RELATIVELY TIGHT PRESSURE GRADIENT SHOULD REMAIN
AS WINDS TURN FROM THE WEST TO SOUTH WITH THE APPROACH OF THE NEXT
SHORT WAVE...KEEPING WINDS FROM COMPLETELY DECOUPLING AND
ALLOWING TEMPS TO DROPS DRAMATICALLY OVERNIGHT.
TUESDAY WILL SEE SNOW IN THE DVL BSN BY 12Z QUICKLY MOVE EAST AND
ACROSS THE N RRV WITH LIKELY POPS AS THE BEST FORCING ALLOWS FOR
ONLY AN INCH OR TWO OF ACCUM ALONG AND NORTH OF HWY 200 AS THE
SYSTEM REMAINS VERY PROGRESSIVE. TIMING OF THE ARRIVAL OF WESTERLY
WINDS AND HOW WELL THEY MIX IN THE VALLEY REMAINS A CONCERN.
MODELS INDICATE 50KTS IN THE 00 TO 06Z TIME FRAME ACROSS THE WEST
AND RRV AT 925MB. HOWEVER THERE REMAINS LITTLE LOW LEVEL CAA AND
LAPSE RATES IN THE LOWEST 500M AT BEST REACH 4 TO 5 C/KM. SO
CURRENT THINKING IS THAT IT MAY BE WINDY BUT DON/T SEE REACHING
ANY HEADLINE CRITERIA EXCEPT FOR THE HIGHER ELEVATIONS IN THE
DVL BSN AND MAYBE SOUTH ALONG THE RIDGE SEPARATING THE JAMES AND
SHEYENNE RIVER VALLEYS FOR A BRIEF PERIOD...MAYBE 2 HOURS...BEFORE
SUNSET.
WINDS TO DIMINISH EARLY WEDNESDAY AS SFC RIDGE AXIS WILL MOVE
ACROSS THE CWFA IN THE AM KEEPING TEMPS SLOW TO RISE EVEN UNDER
MOSTLY CLEAR SKIES. WITH RETURN FLOW SETTING UP IN THE WEST AS
NEXT SFC LOW DEVELOPS IN WESTERN SASKATCHEWAN AND GOOD MIXING
CONTINUING OVERNIGHT MAY SEE LITTLE TO STEADY TEMPS WED PM. BY
THURS AM S SFC WINDS WITH 925MB TEMPS IN THE PLUS 2 TO 3 RANGE
WITH WHAT IS CURRENTLY EXPECTED TO BE FULL SOLAR SHOULD ALLOW
TEMPS TO REACH MID 30S ACROSS THE CWFA.
LONG TERM (THURSDAY NIGHT-MONDAY)...
MEDIUM RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT ON A SIGNIFICANT
PATTERN CHANGE FOR THE PERIOD...BUT DIFFER ON THE PARTICULARS.
THURSDAY NIGHT THE UPPER LOW OVER THE SOUTHERN PLAINS EARLIER WILL
BE EJECTING OUT INTO THE GREAT LAKES...WITH THE MODELS SHOWING
DIFFERENT TIMING AND TRACKS OF THIS SYSTEM. OF BETTER AGREEMENT IS
A LARGE TROUGH JUST TO OUR WEST...LEAVING THE CWA IN SOUTHWESTERLY
FLOW ALOFT. MODELS ALL BRING SOME PRECIP INTO THE SOUTHEASTERN CWA
AS THE SOUTHERN SYSTEM MOVES BY. WILL CONTINUE TO KEEP CHANCE POPS
OVER THAT AREA WITH LESSER CHANCES FURTHER NORTHWEST AS A FRONTAL
BOUNDARY MOVES INTO THE AREA. MODEL SOUNDINGS HAVE A DECENT WARM
LAYER ALOFT THURSDAY NIGHT BEFORE THE COLDER AIR MOVES IN FROM THE
NORTH. MIXED PRECIP IS NOT OUT OF THE QUESTION...ALTHOUGH THE EXACT
TEMPERATURE PROFILE IS STILL VERY UNCERTAIN. WILL INCLUDE A SLEET
MENTION ALONG WITH SNOW THURSDAY EVENING FOR NOW BUT SOME FZRA IS
POSSIBLE DEPENDING ON JUST HOW WARM THE LAYER ALOFT GETS.
PRECIP SHOULD QUICKLY TRANSITION TO ALL SNOW AS THE UPPER TROUGH
MOVES EAST AND COLD AIR FUNNELS IN FROM THE NORTH. CONTINUED TO
KEEP POPS OVER THE AREA THROUGH FRIDAY AND SATURDAY AS A MID LEVEL
DEFORMATION ZONE CONTINUES TO LINGER OVER THE NORTHERN PLAINS. WE
SHOULD BEGIN TO DRY OUT FOR SUNDAY AND MONDAY AS COLD HIGH PRESSURE
BUILDS IN AND SKIES BEGIN TO CLEAR. TEMPS SHOULD DROP TO VALUES
WELL BELOW AVERAGE FOR THE WEEKEND AND INTO MONDAY...WITH HIGHS IN
THE SINGLE DIGITS AND LOWS BELOW ZERO.
AVIATION...
MVFR STRATUS HAS DROPPED FURTHER SOUTH THAN EXPECTED AND IMPACTED
KTVF. THINK THAT THE CEILINGS SHOULD SCATTER OUT IN THE NEXT FEW
HOURS. WEST WINDS WILL DROP INTO THE 10 TO 15 KT RANGE SHORTLY
BEFORE 00Z. THE WINDS WILL GRADUALLY SHIFT AROUND TO THE SOUTH BY
MORNING...AND THEN BY TOMORROW AFTERNOON SHIFT TO THE WEST AGAIN AND
PICK UP ABOVE 15 KTS. THERE WILL BE A PERIOD OF MVFR TO IFR
CEILINGS MOVING FROM WEST TO EAST TOMORROW AND SOME -SN...BUT VISB
ARE EXPECTED TO STAY IN THE 2-5SM RANGE AS SNOW MOVES THROUGH.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
RIDDLE/JK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
322 AM CST SUN JAN 6 2013
.SHORT TERM...TODAY THROUGH MONDAY...
THE MAIN CHALLENGE FOR THE SHORT TERM IS FOG AND STRATUS THIS
MORNING. OTHERWISE...THE BEGINNING OF A PERIOD OF ABOVE AVERAGE
TEMPERATURES WILL HIGHLIGHT THE SHORT TERM.
THE HRRR SO FAR HAS HAD A GOOD HANDLE ON THE STRATUS THROUGH THE
NIGHT THAT HAS SPREAD SOUTHEAST OUT OF SOUTHERN CANADA. EXPECT
MOST AREAS ALONG AND EAST OF A LINE FROM CROSBY THROUGH BISMARCK
AND LINTON TO BE UNDER THE STRATUS DECK BY 12 UTC. DID MAINTAIN THE
MENTION OF PATCHY FOG AND FLURRIES UNDER THIS DECK BASED UPON
SURFACE OBSERVATIONAL TRENDS THROUGH THE NIGHT. HOWEVER...THE
STRATUS DECK SHOULD QUICKLY BEGIN TO ERODE...ESPECIALLY BETWEEN
15-18 UTC...AS SOUTHWESTERLY WINDS IN THE 925-850 MB LAYER
INCREASE.
OTHERWISE FOR TODAY...ALL OF WESTERN AND CENTRAL NORTH DAKOTA WILL
RESIDE WITHIN THE WARM SECTOR OF A SURFACE LOW ACROSS SOUTHEASTERN
SASKATCHEWAN. GIVEN A LOW LEVEL WARM AIR ADVECTION
REGIME IN SOUTHERLY FLOW...THE CHALLENGE IS HOW MUCH WARM AIR CAN
BE MIXED TO THE SURFACE FROM AN INVERSION THAT WILL BE REINFORCED
BY THE SNOWPACK. THE TREND THE PAST COUPLE OF DAYS IN A SIMILIAR
SETUP HAS BEEN FOR THE STATISTICAL GUIDANCE TO BE ABOUT 3 TO 5
DEGREES TOO WARM...AND THE DETERMINISTIC MODELS TO ABOUT THE SAME
AMOUNT TOO COLD. THUS WILL USE A BLEND OF THE TWO GUIDANCE SUITES
WHICH YIELDS HIGHS IN THE LOWER 20S ACROSS THE JAMES RIVER VALLEY
WHERE THE LEAST MIXING IS EXPECTED...TO THE LOW TO MID 30S ACROSS
THE FAR WEST WHERE WINDS TURN SOUTHWEST AHEAD OF AN ADVANCING COLD
FRONT WHICH SHOULD ALLOW FOR GREATER MIXING HEIGHTS TO BE
ACHIEVED.
THE AFOREMENTIONED COLD FRONT PROPAGATES ACROSS THE AREA DURING
THE EVENING AND OVERNIGHT...WITH POST FRONTAL MIXING PREVENTING ANY
FOG FORMATION RESULTING FROM SNOW MELT. CANNOT RULE OUT AN ISOLATED
SNOW SHOWER ACROSS THE FAR NORTH WITH THE PASSAGE OF THE FRONT
CLOSER TO THE STRONGER UPPER LEVEL FORCING. HOWEVER...MOISTURE IS
LIMITED AND MAINTAINED A DRY FORECAST FOR TONIGHT.
FOR MONDAY...DESPITE BEING IN THE WAKE OF A COLD FRONT...GOOD
MIXING FROM WESTERLY WINDS OF 15 TO 20 KTS ARE EXPECTED TO ALLOW
TEMPERATURES TO MIX OUT TO VALUES SIMILIAR TO THOSE SEEN ON
SUNDAY...AND LIKELY WARMER ACROSS THE SOUTH CENTRAL AND JAMES
RIVER VALLEY. WITH A SMALL SPREAD IN FORECAST HIGHS ON THE 00 UTC
STATISTICAL AND DETERMINISTIC GUIDANCE...USED A BLEND OF BOTH
YIELDING HIGHS FROM THE MID 20S NORTH TO THE LOWER 30S SOUTH.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
THE MEDIUM RANGE MODEL CONSENSUS PROGS A CLIPPER SYSTEM TO TRAVERSE
WESTERN AND CENTRAL NORTH DAKOTA MONDAY NIGHT THROUGH TUESDAY. A
WINTRY MIX WILL BE POSSIBLE AROUND THE I-94 CORRIDOR WITH THE PRECIP
TYPE EXPECTED TO GENERALLY BE ALL SNOW NORTH OF I-94 TUESDAY. NEW
SNOWFALL ACCUMULATIONS ARE EXPECTED TO REMAIN LESS THAN 1 INCH.
MAINLY DRY CONDITIONS WITH WELL ABOVE NORMAL TEMPERATURES ARE
FORECAST FOR WEDNESDAY.
THE GEM/GFS/ECMWF HAVE SLOWED THE PROGRESSION OF A LONG WAVE TROUGH
ACROSS THE WESTERN CONUS AND ITS ATTENDANT COLD FRONT INTO NORTH
DAKOTA THURSDAY. GIVEN THE SLOWER PROGRESSION...MAINTAINED THE
SLIGHT CHANCES FOR PRECIPITATION WEST THURSDAY...THEN BROAD BRUSHED
CHANCE/SLIGHT CHANCE POPS ACROSS THE ENTIRE CWA THURSDAY NIGHT. THE
SLIGHT CHANCES FOR SNOW SHOULD TAPER OFF FRIDAY.
MUCH COLDER AIR IS THEN EXPECTED TO PLUNGE ACROSS THE NORTHERN
PLAINS BEHIND THE FRONT. WELL BELOW NORMAL TEMPERATURES ARE EXPECTED
FRIDAY AND SATURDAY AS A RESULT. HIGHS ARE GENERALLY EXPECTED TO
RANGE FROM THE SINGLE DIGITS TO THE TEENS ABOVE ZERO. LOWS ARE
FORECAST TO RANGE FROM THE SINGLE DIGITS BELOW TO SINGLE DIGITS
ABOVE ZERO BY THE END OF THE WEEK.
&&
.AVIATION...
IFR CIGS IN STRATUS WILL CONTINUE TO DIVE SOUTHEASTWARD
ACROSS CENTRAL AND EASTERN NORTH DAKOTA THIS MORNING. KBIS WILL BE
ON THE FRINGE OF THIS STRATUS DECK...HENCE THE TEMPO IFR GROUP.
HOWEVER...KMOT/KJMS SHOULD REMAIN IFR THROUGH MID-MORNING...THEN
BECOME VFR BY LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED FOR
WESTERN AND CENTRAL NORTH DAKOTA FROM THIS AFTERNOON THROUGH THE
REMAINDER OF THE TAF PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AYD
LONG TERM/AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1240 AM CST SUN JAN 6 2013
.DISCUSSION...
SIGNIFICANT CHANGES TO OVERNIGHT SKY COVER WERE MADE WITH THIS
FORECAST UPDATE AS LOW LEVEL STRATUS CONTINUES TO SPREAD SOUTHEAST
OUT OF SOUTHERN CANADA. THE LATEST RUNS OF THE HRRR HAVE A GOOD
HANDLE ON THIS DECK...AND WILL FOLLOW IT FOR CLOUD COVER
THROUGH THE NIGHT...WITH ALL AREAS ALONG AND EAST OF A LINE FROM
CROSBY THROUGH BISMARCK AND FORT YATES TO BE UNDER THE DECK BY 12
UTC. BASED UPON THE LATEST SURFACE OBSERVATIONAL TRENDS...PATCHY
FOG AND FLURRIES ARE ALSO ASSOCIATED WITH THE STRATUS DECK AND
REFLECTED THIS IN THE GRIDS FOR ALL AREAS TO BE IMPACTED BY THE
STRATUS.
&&
.AVIATION...
A SHIELD OF MAINLY IFR STRATUS WILL CONTINUE TO DROP SOUTH THROUGH THE
OVERNIGHT HOURS. LATEST SATELLITE TRENDS AND SHORT RANGE RH PROGS
INDICATE ALL TAF SITES EXCEPT KDIK WILL BE IMPACTED...ESPECIALLY
KMOT/KBIS/KJMS. SOME PERIODS OF MVFR FOG ARE ALSO POSSIBLE. LOWER
CLOUDS WILL SCATTER OUT BY MID TO LATE MORNING AS SOUTHERLY WINDS
PICK UP.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
AVIATION...RK
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
530 PM CST MON JAN 7 2013
.DISCUSSION.../ISSUED AT 343 PM/
MULTIPLE PLAYERS IN TODAY/S FORECAST FOR TONIGHT INTO TOMORROW.
CURRENTLY...MOSTLY CLEAR SKIES ACROSS THE AREA WITH A FEW HIGH
CLOUDS ACROSS CENTRAL SOUTH DAKOTA. THE SUNSHINE HAS PROMOTED SNOW
MELT...BUT WITH WEAK WINDS AND STRONG INVERSION...MOISTURE REMAINS
IN THE NEAR SURFACE LAYER. COULD SEE FOG DEVELOP OVERNIGHT
TONIGHT...BUT TRICKY TO PIN POINT WHERE EXACTLY. HRRR CONTINUES TO
SUGGEST THAT PATCHY FOG WILL BE POSSIBLY ACROSS THE NORTH...WHILE
NAM FOCUSES ON THE SOUTH AND EAST. HAVE SIDED CLOSER TO NAM...BUT
WITH WEAK WINDS...COULD GET RADIATIONAL FOG NEARLY ANYWHERE CLEAR
SKIES REMAIN FOR A FEW HOURS. AS MENTIONED IN THE MORNING
DISCUSSION...AMPLIFYING WAVE MOVING ACROSS THE AREA LATE TONIGHT
WITH UPPER LEVEL DIV Q INCREASING AFTER 06Z MAINLY ACROSS THE
NORTHERN HALF OF THE FORECAST AREA. WITH FAIRLY DRY AIR THROUGH THE
MID LEVELS OF THE ATMOSPHERE...AM NOT EXPECTING ANY PRECIPITATION
AND DROPPED MENTION OF SPRINKLES/FLURRIES FROM THE FORECAST. IF FOG
DEVELOPS IN THE SOUTHEAST...WILL NEED TO KEEP AN EYE ON DRIZZLE
POTENTIAL WITH WEAK LIFT IN THE LOW LEVELS OF THE ATMOSPHERE.
COLD FRONT IS POISED TO MOVE THROUGH THE AREA ON TUESDAY. SOUTHERLY
WINDS WILL BECOME WEST AND SOMEWHAT GUSTY BEHIND THE FRONT WITH
20-30 KNOTS OF FLOW AT 925 HPA. NOT MUCH IN THE WAY OF COLD AIR
ADVECTION BEHIND THE FRONT...AND WITH ONLY MEAGER PRESSURE RISES AND
STRONG INVERSION REMAINING ALOFT...WILL STRUGGLE TO GET A LOT OF THE
MOMENTUM DOWN THE SURFACE. STRONGEST WINDS WILL LIKELY BE ACROSS
THE NORTHERN EDGE OF THE FORECAST AREA WITH STRONGEST GRADIENT WINDS
THERE...BUT STILL LOOK TO REMAIN BELOW ADVISORY CRITERIA.
UPPER LEVEL TROUGH IS EXPECTED TO DIG ACROSS THE DESERT SOUTHWEST
MID WEEK...WHICH PUSHES THE RIDGE AXIS OVER THE FORECAST AREA ON
WEDNESDAY. EXPECT ANOTHER RELATIVELY MILD DAY WITH MOSTLY SUNNY
SKIES AND ABOVE NORMAL TEMPERATURES. EXPECT HIGHS TO REACH JUST
ABOVE FREEZING IN SOUTHWEST MINNESOTA AND ADJACENT AREAS...NUDGING
INTO THE UPPER 30S IN NORTHWEST IOWA. THE WARMEST READINGS WILL BE
FOUND IN SOUTH CENTRAL SOUTH DAKOTA WITH THE MID OR UPPER 40S IN
AREAS WHERE MUCH OF THE SNOWPACK HAS MELTED.
FOR THURSDAY...A CUT OFF LOW IS EXPECTED TO FORM IN THE SOUTHWEST
PLAINS AND TRACK NORTHEAST INTO THE NORTHERN GREAT LAKES EARLY
SATURDAY. SOME MODEL DIFFERENCES STILL EXIST...WITH THE ECMWF AND
GEM STILL FOLLOWING A SLOWER AND SLIGHTLY MORE SOUTHERLY TRACK. ALL
MODELS DO CLIP OUR SOUTHEASTERN COUNTIES AS THE SURFACE LOW TRACKS
INTO IOWA THURSDAY EVENING. TEMPERATURES WILL BE PARTICULARLY TRICKY
WITH READINGS EXPECTED TO RISE UP ABOVE FREEZING BY THE AFTERNOON.
WITH VERY WARM LOW LEVELS...EXPECT PRECIPITATION TO BE ENTIRELY
LIQUID FOR THIS SYSTEM...BUT WITH SURFACE READINGS POTENTIALLY BELOW
FREEZING IN THE MORNING AND AGAIN THURSDAY NIGHT...FREEZING RAIN
WILL ALSO BE POSSIBLE. BUT GIVEN THAT THESE TEMPERATURES WILL ONLY
BE A DEGREE OR TWO BELOW FREEZING...ICE ACCUMULATION DOES NOT LOOK
TO BE SIGNIFICANT. BUT WILL STILL CONTINUE TO MONITOR FOR ANY
CHANGES IN THIS OUTLOOK.
TEMPERATURES ON FRIDAY WILL LIKELY BE SOMEWHAT STEADY OR BEGIN TO
FALL IN THE AFTERNOON AS COOLER TEMPERATURES BEGIN TO FILTER INTO
THE AREA BEHIND THIS SYSTEM. THE BROAD POSITIVELY TILTED TROUGH
DIGGING ACROSS THE SOUTHWEST PUSHES INTO THE WESTERN PLAINS FRIDAY
EVENING...BRINGING THE NEXT POTENTIAL FOR WET WEATHER TO REGION
FRIDAY NIGHT AND SATURDAY. AGAIN...THE ECMWF IS A BIT SLOWER AND
SHOWS MORE OF A CLOSED UPPER LEVEL FEATURE. A SLIGHT CHANCE FOR SOME
LIGHT SNOW OR FLURRIES WILL BE POSSIBLE AHEAD OF THE MAIN WAVE ON
FRIDAY. THE DETAILS ARE STILL QUITE UNCERTAIN AT THIS POINT...BUT
THE GFS APPEARS TO TAKE THE BEST DYNAMICS WEST AND NORTH OF THE
FORECAST AREA...WHILE THE ECMWF HAS A BIT MORE ORGANIZATION WITH A
DECENT BAND OF MID LEVEL FRONTOGENESIS MOVING THROUGH THE FORECAST
AREA. WILL KEEP MENTION OF POPS AS A HIGH CHANCE FOR SOME LIGHT
SNOWFALL FRIDAY NIGHT AND SATURDAY. PRELIMINARY AMOUNTS LOOK LIKE A
FEW INCHES WOULD BE POSSIBLE ACROSS THE CWA.
THE LOW EXITS THE AREA SATURDAY NIGHT WITH A STRONGER SHOT OF COLD
AIR ADVECTION ARRIVING IN ITS WAKE. TEMPERATURES WILL BE MUCH COOLER
FOR THE START OF NEXT WEEK WITH HIGHS MAINLY IN THE TEENS AND LOWS
AROUND ZERO.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
CRITICAL ISSUE FOR THE NIGHT WOULD BE POTENTIAL FOR IFR CEILING AND
VISIBILITY DEVELOPMENT AFTER A DAY OF MELTING...WITH WEAK HIGH
PRESSURE SLOWLY PUSHING EAST ACROSS THE AREA. AFTER PERUSING THE
VARIOUS LOWER LEVEL THERMAL PROFILES...SEEMS MORE LIKELY TO BE A
SITUATION WHERE WILL FROST OUT A GOOD DEAL OF THE SUB INVERSION
MOISTURE WITH TEMP/DEWPOINT PROFILES CRASHING IN TANDEM...RATHER
THAN A MORE WIDESPREAD FOG DEVELOPMENT. WILL LIKELY DEAL WITH A
LONGER PERIOD OF BORDERLINE MVFR VISIBILITIES WITH STRONG INVERSION
LINGERING ALL THE WAY THROUGH THE MORNING...AND PERHAPS EVEN UNTIL
WIND SHIFT IN THE AFTERNOON FOR KFSD AND KSUX. RETAINED A
FEW-SCATTERED MENTION FOR LOWER CEILINGS...BUT THINK MORE PROBABLE
EVENT WOULD BE MVFR VISIBILITIES...AND HAVE PLACED THOSE CONDITIONS
IN PREVAILING. WINDS WILL INCREASE BEHIND BOUNDARY...AND MODELS
APPEAR TO HANG ON TO TOO COOL SURFACE LAYER TEMPS AND DO NOT ALLOW
FOR THE BETTER MIXING THAT PROGGED SURFACE READINGS WOULD ALLOW...
SO PUT IN SOME WIND GUSTS DURING THE AFTERNOON EXCEEDING 25 KNOTS
AROUND KHON...AND CLOSE TO THRESHOLD FOR KFSD/KSUX A BIT LATER INTO
THE AFTERNOON. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1054 PM CST SAT JAN 5 2013
.DISCUSSION.../ISSUED AT 930 PM CST/
LOW CLOUDS ARE CLEARING VERY STRONGLY. LINGERING BAND OF LOW LEVEL
MOISTURE WEST WAITING FOR WARM ADVECTION TO START LOOKS TOO WEAK
WITH CLOUDS THERE RAPIDLY DISSIPATING...AND GIVEN NEW NAM RH
FIELDS...REDEVELOPMENT NOT EXPECTED. SKIES SHOULD GO CLEAR TO MOSTLY
CLEAR TONIGHT. FOR THIS HAVE ALLOWED TEMPERATURES A LITTLE BETTER
LATE DROP AS WINDS CONTINUE TO DECREASE WITH LOWS 2 TO 4 DEGREES
LOWER THAN BEFORE. WHILE SOME WARM ADVECTION UPSTAIRS WILL START
SOON...SURFACE SHOULD BE IGNORED ON THIS TONIGHT. LOW TEMPS IN THE
SINGLE DIGITS EVERYWHERE AND MAYBE A ZERO HERE AND THERE.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
MVFR STRATUS SHOULD EXIT FAR SOUTHERN PORTIONS OF THE FORECAST AREA
EARLY IN THE PERIOD...07Z-08Z...TAKING ANY FLURRIES ALONG WITH IT.
RELATIVELY NARROW BAND OF LOW MVFR-IFR STRATUS DRIFTING SOUTHEAST
THROUGH NORTHEAST/EAST CENTRAL SD AND FAR WESTERN MN AT THE START OF
THE PERIOD WILL SLIDE MAINLY EAST OF I-29 CORRIDOR...DRIFTING ACROSS
SOUTHWEST MN/NORTHWEST IA THROUGH EARLY SUNDAY MORNING. COULD SCRAPE
CLOSE ENOUGH TO KFSD TO GIVE BRIEF PERIOD OF MVFR-IFR CEILINGS 07Z
TO 09Z WINDOW...BUT CONFIDENCE IN WESTWARD EXTENT IS LOW...SO WILL
KEEP TAF IN VFR RANGE. LINGERING NORTHWESTERLY WIND GUSTS 20-25KTS
OVER SOUTHEAST HALF OF THE FORECAST AREA WILL CONTINUE TO SLOWLY
SUBSIDE THROUGH THE OVERNIGHT HOURS...WITH LIGHT/VARIABLE WINDS
BECOMING SOUTH MOST AREAS BY SUNDAY AFTERNOON. INCREASING SOUTHERLY
FLOW EXPECTED TO SPREAD ACROSS THE AREA LATE SUNDAY AFTERNOON AND
EVENING...WITH GUSTS 20-25KTS LIKELY WEST OF JAMES RIVER VALLEY LATE
SUNDAY AFTERNOON...AND OVER MUCH OF SOUTHEAST SD/SOUTHWEST MN SUNDAY
EVENING.
&&
.PREV DISCUSSION.../ISSUED AT 342 PM CST/
UPPER WAVE PUSHING ACROSS THE DAKOTAS THIS AFTERNOON...DRIVING COLD
FRONT INTO THE FAR EASTERN PORTIONS OF THE STATE AT MID AFTERNOON.
CLOUDS PUSHING IN WITH STRONG COLD AIR ADVECTION...AND WITH OFF
SURFACE TEMPS FALLING QUICKLY TOWARD THOSE FAVORING ICE NUCLEATION...
HAVE SEEN FLURRIES DROP IN TO PARTS OF EAST CENTRAL SOUTH DAKOTA.
THE CLOUDS AND FLURRIES WILL CONTINUE TO PUSH EAST AND SOUTHEAST
THIS EVENING...BUT IT IS CERTAINLY A CHALLENGE AS TO HOW QUICKLY TO
BRING IN A MORE PERMANENT CLEARING. RAP AND 18Z NAM ARE NOW IN
FAVOR OF HANGING BACK A PERIOD OF LOWER CLOUDS LATER INTO THE NIGHT
NEAR/WEST OF THE JAMES RIVER AND THEN DRIFTING EAST AS FLOW ALOFT
STARTS TO TURN A BIT MORE WESTERLY. THIS ALSO PRESENTS A LARGE
CHALLENGE TO TEMPERATURES...WHICH WILL PROVE ALMOST IMPOSSIBLE TO
GET CLOSE ON AN HOURLY TIME FRAME WITH IN AND OUT CLOUD TRENDS.
EXPECT A BETTER PUSH OF CLEARING THROUGH THE EASTERN CWA BY LATER
EVENING...BUT ENOUGH WIND OR A FEW MORE CLOUDS LIKELY TO KEEP TEMPS
FROM PLUNGING TOO FAR ANYWHERE. GENERALLY LOOKING FOR QUITE A FEW
SINGLE DIGITS...WITH READINGS AROUND 10 WEST AS WARMER AIR SHUNTS
EAST FAIRLY QUICKLY.
SUNDAY AGAIN PRESENTS A SMALL CHALLENGE TO TEMPS...WITH A VERY
WEAK GRADIENT THROUGH MIDDAY OR EVEN EARLY AFTERNOON IN THE FAR
SOUTHEAST. LOWER ELEVATION LOCATIONS COULD EASILY ONCE AGAIN FIND
THEMSELVES MIRED IN CHILLIER AIR...WITH THE INCREASING SOUTHERLY
GRADIENT MAINLY ACROSS SOUTHEAST SOUTH DAKOTA AND INTO SOUTHWEST
MINNESOTA DURING THE AFTERNOON. HIGH CLOUDS PUSHING ACROSS WOULD
ONLY ENHANCE THE POTENTIAL FOR THIS TO OCCUR...SO WAS CAREFUL TO
NOT WARM CONDITIONS IN THE EAST TOO MUCH...AND DID NUDGE SOME
TEMPERATURES DOWN ACROSS PARTS OF NW IA. THE WEST WILL BE OPEN TO
SOME BETTER WARMING...BUT EVEN THERE THE INVERSION WILL PRESENT A
BIT OF A CHALLENGE TO LOWER ELEVATION WARMING. /CHAPMAN
THE PATTERN OF MILD WEATHER WILL CONTINUE THROUGH MUCH OF THE WEEK
AS A MORE ZONAL PATTERN SETS UP FOR THE FIRST HALF OF THE WORK WEEK.
MILDER WEST TO SOUTHWEST FLOW WILL MAKE TEMPERATURES QUITE TRICKY TO
PINPOINT...PARTICULARLY REGARDING OVERNIGHT LOWS. FOR SUNDAY
NIGHT...BREEZY SOUTH TO SOUTHWEST WINDS WILL LIKELY RESULT IN A
NON-DIURNAL TEMPERATURE TREND WITH LOWS EXPECTED IN THE EVENING OR
SHORTLY AFTER MIDNIGHT...THEN SLOWLY RISING LATE. THE QUESTION IS
HOW COOL WE WILL BE ABLE TO FALL OFF IN THE EVENING. OTHERWISE...
HIGH TEMPERATURES FOR TUESDAY AND WEDNESDAY WILL LIKELY BE NEAR OR
JUST ABOVE FREEZING...WITH THE HIGHS IN THE LOW 40S POSSIBLE IN
SOUTH CENTRAL SD WHERE THE GREATEST POTENTIAL MIXING OF THE MILD LOW
LEVEL TEMPERATURES COULD OCCUR.
LATEST MODEL RUNS SHOWING A LITTLE BETTER AGREEMENT FOR THE SYSTEM
ON WEDNESDAY NIGHT AND THURSDAY...BUT DIVERGE A BIT LEADING INTO
NEXT WEEKEND. ALSO OF NOTE ARE SOME PRETTY BIG CHANGES FROM EARLIER
MODELS RUNS. LATEST 12Z RUNS OF GFS AND ECMWF ARE MUCH SLOWER AND
FURTHER SOUTH WITH THE CLOSED LOW SYSTEM...RESULTING IN LITTLE TO NO
IMPACT ACROSS OUR FORECAST AREA. WENT AHEAD AND REMOVED MENTION OF
POPS FOR WEDNESDAY GIVEN THE SLOWER TIMING. DECIDED TO KEEP MENTION
OF LOW CHANCE POPS MAINLY IN NORTHWEST IOWA ON THURSDAY GIVEN THE
RECENT INCONSISTENCIES BETWEEN MODEL RUNS...BUT DID TRIM BACK
COVERAGE AND QUITE A BIT FROM THE ALL BLEND...WHICH WAS BIASED FROM
THE 00Z ECMWF RUN. TEMPERATURES REMAIN QUITE MILD INTO THURSDAY...
BRINGING THE QUESTION OF PRECIPITATION TYPE IF THIS SYSTEM DOES
GRAZE OUR SOUTHEAST CWA. GIVEN WHAT LOOKS LIKE VERY MILD LOW/MID
LEVELS...PRECIPITATION TYPE MAY BECOME A CONCERN EARLY THURSDAY...
BUT WITH MANY FACTORS UP IN THE AIR...WILL KEEP IT SIMPLE WITH A
RAIN AND SNOW MIX.
THE NEXT AREA OF UNCERTAINTY IS REGARDING A STORM SYSTEM AROUND THE
SATURDAY TIME FRAME. MODELS CONTINUE TO FLIP FLOP WITH
SOLUTIONS...RESULTING IN LARGE TEMPERATURE AND POP DIFFERENCES. NOT
A WHOLE LOT OF CONFIDENCE...ESPECIALLY WITH THE VERY EXTREME GFS
SOLUTION. IT DOES LOOK LIKE A BIT OF A COOL DOWN FRIDAY AND SATURDAY
COMPARED TO EARLIER IN THE WEEK...BUT NOTHING TOO EXTREME. DID NOT
ALTER MUCH FROM THE ALLBLEND.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CST SAT JAN 5 2013
.SHORT TERM...TONIGHT
645 PM CST SAT JAN 5 2013
HAVE MADE SOME UPDATES TO THE FORECAST THIS EVENING WITH THE
PROSPECTS FOR DRIZZLE/FREEZING DRIZZLE. FIRST...TEMPERATURES HAVE
REMAINED ABOVE FREEZING IN THE WARM SECTOR AHEAD OF THE COLD FRONT
THAT CURRENTLY RUNS THROUGH NORTHEAST IOWA UP TO A TRIPLE POINT IN
WESTERN WISCONSIN WITH A WARM FRONT EXTENDING EAST ACROSS
WISCONSIN TOWARD GREEN BAY. CEILINGS FROM NORTHEAST IOWA INTO
SOUTHWEST WISCONSIN HAVE NOT BEEN AS LOW AS YOU WOULD WANT FOR
DRIZZLE TO OCCUR WITH THEM BEING AT 2-4KFT. OBSERVATIONS FROM DOWN
IN THIS REGION ALL SHOW VISIBILITY UP AT GREATER THAN 6SM WITH NO
REPORTS OF DRIZZLE THIS AFTERNOON/EARLY EVENING. 05.22Z RAP
SOUNDINGS OUT OF DBQ SEEM TO PAINT THE PICTURE WELL WITH A
SATURATED...PROBABLY OVERLY SATURATED...LOW LEVEL WITH NO VERTICAL
MOTIONS. BASED ON THESE FACTORS...HAVE REMOVED THE FREEZING
DRIZZLE/DRIZZLE MENTION FOR THIS EVENING.
THE SECOND WAVE THEN COMES IN AS A SECONDARY COLD FRONT WHICH
CURRENTLY IS DROPPING SOUTH ON THE BACK SIDE OF THE SURFACE LOW
ACROSS SOUTHERN MINNESOTA. THERE IS A BRIEF PERIOD OF
CLEARING...BUT THEN THERE IS A PATCH OF LOW LEVEL CLOUD COVER
TRACKING TO THE SOUTHEAST FROM SOUTH DAKOTA INTO CENTRAL IOWA.
MODELS HAVE BEEN OVER-DOING THE LOW LEVEL MOISTURE WITH THIS
FEATURE AND SHOW THAT WE SHOULD BE COMPLETELY OVERCAST AT THIS
POINT. HAVE LEFT SKY CONDITIONS AS MOSTLY CLOUDY TO CLOUDY
TONIGHT...BUT THAT MAY BE ON THE PESSIMISTIC SIDE GIVEN CURRENT
UPSTREAM CONDITIONS. 05.22Z RAP SOUNDINGS DO SHOW THAT IF THE LOW
LEVEL DECK DOES OCCUR THAT IT SHOULD BECOME COLDER THAN -8C THAT
ICE WOULD BE INTRODUCED. WITH WEAK FORCING...SHOULD SEE SOME
FLURRIES/SNOW SHOWERS WITH IT. THE LOW VISIBILITIES CURRENTLY
OCCURRING IN WEST CENTRAL MINNESOTA ARE FROM SNOW SHOWERS THOUGH
THEY ARE NOT SHOWING UP ON RADAR BECAUSE THE CLOUD DECK IS JUST A
FEW HUNDRED FEET OFF THE GROUND AND BELOW THE RADAR BEAM. THIS
AREA APPEARS TO BE RUNNING SOUTH OF THE FORECAST AREA...BUT WILL
HAVE TO MONITOR IT FOR WHETHER SOME SMALL ACCUMULATIONS NEED TO BE
ADDED OVERNIGHT.
.LONG TERM...TUESDAY THROUGH SATURDAY
201 PM CST SAT JAN 5 2013
MEDIUM RANGE MODELS HAVE STARTED TO COME INTO BETTER AGREEMENT
WITH THE SYSTEM EXPECTED TO IMPACT THE GREAT LAKES FOR THE LATTER
HALF OF THE WEEK. THE 05.00Z ECMWF HAS REMAINED CONSISTENT WITH
ITS PREVIOUS RUNS ON THE TRACK OF THE SYSTEM WHILE THE 05.12Z GFS
HAS SHIFTED CONSIDERABLY TOWARD THE ECMWF SOLUTION. THE MODELS ARE
NOW VERY SIMILAR IN TIMING BUT THE GFS STILL DOES NOT BRING THE
SYSTEM AS FAR NORTH AS THE ECMWF. BY 11.00Z /FRIDAY EVENING/ THE
ECMWF PLACES THE UPPER LEVEL LOW NEAR THE WISCONSIN-ILLINOIS
BORDER BETWEEN KDBQ AND KRST WHILE THE GFS IS FARTHER SOUTH NEAR
KSTL. THE AGREEMENT THAT WAS IN PLACE HAS BEEN THROWN OUT THE
WINDOW BY THE 05.12Z ECMWF HAS IT HAS COME IN SLOWER AND FARTHER
SOUTH AND IS NOT SIMILAR WITH ITS TRACK TO THE GFS. WITH THE
DISPARITY BETWEEN THE MODELS...THE ONLY CHANGE MADE TO THE MODEL
CONSENSUS GRIDS WAS TO WEDNESDAY NIGHT. WITH THE ECMWF NOW BEING
SLOWER...IT SUGGESTS THE PRECIPITATION WILL NOT MOVE IN UNTIL
THURSDAY...SO WILL NOW GO WITH A DRY WEDNESDAY NIGHT. THE
PRECIPITATION FROM THIS SYSTEM SHOULD START TO MOVE OUT THURSDAY
NIGHT OR FRIDAY BUT WILL QUICKLY BE FOLLOWED BY THE NEXT SYSTEM.
THE MODELS MAINTAIN A SOUTHWEST FLOW ALOFT BEHIND THIS SYSTEM AND
QUICKLY EJECT OUT ANOTHER SYSTEM FROM THE SOUTHERN ROCKIES. THE
ECMWF IS QUICKER AND FARTHER NORTH THAN THE GFS IN THE UPPER
LEVELS...BUT THE SURFACE TRACKS LOOK TO BE SIMILAR GOING FROM NEAR
KMCI TOWARD KMKE EITHER SATURDAY OR SATURDAY NIGHT. THE ECMWF
SUGGESTS THE FIRST SYSTEM WILL BRING ENOUGH WARM AIR NORTH TO
PRODUCE PRIMARILY RAIN OR A RAIN/SNOW MIX. HOWEVER...THE
BAROCLINIC ZONE LEFT BEHIND MAY BE JUST TO THE SOUTHEAST GIVING
THE SECOND SYSTEM ENOUGH COLD AIR TO WORK WITH TO PRODUCE MAINLY
SNOW.
&&
.AVIATION...THROUGH 06Z MONDAY
1138 PM CST SAT JAN 5 2013
CONFIDENCE IS NOT HIGH WITH THE SKY CONDITIONS OVERNIGHT AS THE
LOW LEVEL CLOUD DECK HAS NOT FILLED IN AS ANTICIPATED ACROSS THE
REGION. HOWEVER...ANOTHER ROUND OF MVFR 1-2.5KFT STRATUS APPEARS
TO BE DROPPING SOUTH OF OUT NORTHWEST WISCONSIN AND NORTHEAST
MINNESOTA PER THE LATEST IR SATELLITE IMAGERY/SURFACE
OBSERVATIONS. WILL CARRY SOME LOWER CEILINGS THROUGH THE OVERNIGHT
HOURS TO ACCOUNT FOR THIS WHICH SHOULD HOLD ON INTO THE MORNING
HOURS AND POSSIBLY INTO THE EARLY AFTERNOON. CAN NOT RULE OUT A
FEW FLURRIES AS THIS CLOUD DECK MOVES IN...BUT THEY SHOULD NOT BE
STRONG ENOUGH TO DROP VISIBILITY DOWN BELOW 6SM. SKIES SHOULD
CLEAR INTO THE AFTERNOON ON SUNDAY AS THE SYSTEM PULLS OFF TO THE
EAST AND DRIER AIR MOVES IN BEHIND IT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
201 PM CST SAT JAN 5 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
336 AM CST Tue Jan 8 2013
.DISCUSSION...
In the short term, concerns are focused on temperatures along with
rainfall potential Wednesday night into Thursday. Early this morning,
a large upper level low continued to spin over northern Mexico as a
progressive upper trough crosses the Northern Plains. Due to an
enhanced area of cirrus moving across the region, temperatures have
remained in the 30s in most locations.
Today: Upper troughing in the Northern Plains will establish weak
surface troughing across portions of east central Kansas through
northwestern Missouri. Winds ahead of this surface trough will again
become breezy by afternoon, with abnormally warm 950:850 temperatures
supporting temperatures into the 50s in many areas. Again, have
followed short term RAP guidance for temperatures this afternoon
which did an excellent job on Monday. The warmest temperatures may
pool just ahead of this surface trough where readings could spike
into the middle 50s.
Tonight: The weak surface trough will move into the region washing
out as it does so. A bit less cirrus may be possible given the
northwesterly upper level flow. The resultant temperatures will fall
into the upper 20s in most locations.
Wednesday: The upper level low over northern Mexico will finally
become dislodged as troughing enters the Pacific Northwest. Locally,
an elongated west to east ridge of high pressure will remain over the
area throughout the daytime hours, keeping winds light and variable.
Temperatures, given the weak boundary and low level flow, will not be
quite as warm as on Tuesday but should still climb near 50.
Wednesday night: The upper level low will quickly begin to surge
north by Wednesday evening with strong low-level moisture advection
headed into the area. Showers and even embedded thunderstorms will
overspread the area through the overnight hours. Models in reasonable
agreement (less the NAM) that rain will reach the Interstate 70
corridor by midnight and northern Missouri by daybreak.
Thursday: Tricky forecast as models indicate the deep upper low will
lift across the CWA during the daytime hours. Rain should quickly
lift northward in the morning, replaced with low cloud cover and
periods of showers/drizzle. Temperatures will be rather difficult and
highly dependent on the track of surface low pressure and surge of
warm air ahead of the surface low. Model guidance suggests a weak
surface low tracking north along with the upper low through eastern
Kansas by Thursday afternoon. NAM is the most aggressive bringing near
60 degree readings into the CWA, but it is also the deepest and most
progressive solution of all guidance. Prefer the weaker solutions of
the GFS/SREF which still bring low 50s by the late afternoon hours.
Dux
Medium Range (Friday through Monday)...
The medium range should start out very warm especially for the
climatologically coldest week of the year for Kansas City (January
10-17). With 850mb temps between 12C-14C, if we can mix out enough,
temperatures could easily range into the mid 50s to mid 60s.
However, those warm temperatures will be short-lived as a cold front
is forced into the forecast area Friday night in association with a
broad and deep upper level trough that will be traversing the
Rockies. This frontal passage looks to be dry as models are in good
agreement that the best moisture transport is south and east of the
forecast area. As such have lowered chance POPs inherited by the
initialization to silent slight chance POPs for Saturday. The main
effect of this cold front will be the marked change in temperatures.
High temperatures across the CWA Saturday will experience a 20
degree range from near 30 across northern Missouri where cold air
advection will be ongoing by day break...to near 50 across central
Missouri where cold air doesn`t begin to advect in until later in
the day. The upper level trough moves through the area on Sunday as
high pressure builds in at the surface with highs in the mid 20s to
lower 30s. Surface high pressure strengths over the area on Monday
and with abundant sunshine highs will return to near normal for the
coldest climatological week of the year with highs in the 30s.
73
&&
.AVIATION...
No changes for the 06Z TAFs.
Other than periods of broken cirrus, TAFs will feature rather benign
conditions over the next 24 hours. Winds will remain 8-10 knots at
MCI, but should decouple at MKC/STJ. With the eastern edge of a
modest nocturnal jet brushing across STJ overnight, significant low
level turning (40-50 degrees) and speed shear (30-35 knots) has
resulted in the introduction of LLWS for STJ from midnight through
late morning when sufficient mixing depth will eliminate the abrupt
inversion. Surface winds should increase to 10-14 knots with a
gradual veering toward the southwest during the day, and then toward
the west-southwest during the evening.
Bookbinder
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1108 PM CST MON JAN 7 2013
.AVIATION...
06Z TAFS FOR KOMA...KLNK...KOFK.
FOG HAD DEVELOPED OVER PARTS OF THE AREA...MAINLY WHERE THERE WAS
MELTING DURING THE DAY AND SIGNIFICANT SNOW COVER REMAINED IN
PLACE. DID MAKE SOME ADJUSTMENTS TO THE TAFS FOR THE OVERNIGHT
HOURS AND INTO TUESDAY MORNING. SOME IFR VISIBILITIES WILL BE
POSSIBLE...ESPECIALLY FROM BETWEEN 09Z AND 14Z. WILL CONTINUE TO
MONITOR FOR DENSE FOG DEVELOPMENT AND AMEND AS NEEDED. LIGHT WINDS
TONIGHT WILL BECOME SOUTHERLY TUESDAY MORNING THEN SHIFT TO WEST
OR SOUTHWEST IN THE AFTERNOON.
MILLER
&&
.PREV DISCUSSION... /ISSUED 1013 PM CST MON JAN 7 2013/
UPDATE...
PUBLIC FORECASTS WERE AMENDED TO INCLUDE SOME MENTION OF DENSE
FOG OVER AREAS THAT HAVE SNOW COVER. ALSO DECREASED LOWS A BIT IN
SOME LOCATIONS.
MILLER
&&
PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY.
MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF
SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO
THURSDAY.
DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT
SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA...
TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN
SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW
FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON.
INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN
THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE
BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN
AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST.
FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL
TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING
TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A
WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL
EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE.
TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT
AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME
FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER
IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR
WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS
THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH
TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE
AREA AS RAIN CONTINUES.
FOBERT
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO
LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE
NEEDED TO GOING FCST.
HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER
IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT.
MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM
CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN
TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS
SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE
BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING
MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR
SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA
FRIDAY NIGHT.
ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL
SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT
VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND
LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH
SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA
DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD
VERIFY.
OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO
EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE
LOWER/MID 20S.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS OMAHA/VALLEY NE
1013 PM CST MON JAN 7 2013
.UPDATE...
PUBLIC FORECASTS WERE AMMENDED TO INCLUDE SOME MENTION OF DENSE
FOG OVER AREAS THAT HAVE SNOW COVER. ALSO DECREASED LOWS A BIT
IN SOME LOCATIONS.
MILLER
&&
.PREV DISCUSSION... /ISSUED 522 PM CST MON JAN 7 2013/
AVIATION...
00Z TAFS FOR KOMA...KLNK...KOFK.
WILL HAVE TO MONITOR FOR DEVELOPMENT OF STRATUS AND FOG TONIGHT.
DID MENTION SOME MVFR VISIBILITIES LATER TONIGHT BUT DID NOT WANT
TO GET TOO PESSIMISTIC. GFS MODEL DOES NOT DEVELOP FOG...WHILE
THE NAM DOES. GENERALLY FELT THE NAM LOW LEVEL MOISTURE WAS
OVERDONE BUT WILL MONITOR AND AMEND TAFS THROUGH THE EVENING AS
NEEDED.
MILLER
PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY.
MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF
SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO
THURSDAY.
DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT
SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA...
TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN
SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW
FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON.
INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN
THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE
BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN
AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST.
FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL
TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING
TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A
WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL
EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE.
TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT
AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME
FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER
IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR
WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS
THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH
TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE
AREA AS RAIN CONTINUES.
FOBERT
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO
LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE
NEEDED TO GOING FCST.
HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER
IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT.
MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM
CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN
TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS
SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE
BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING
MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR
SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA
FRIDAY NIGHT.
ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL
SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT
VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND
LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH
SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA
DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD
VERIFY.
OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO
EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE
LOWER/MID 20S.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 305 AM TUESDAY...
TODAY...
A 1030MB SURFACE HIGH CENTERED OVER THE VA TIDEWATER AREA EXTENDS
SOUTHWEST ACROSS CENTRAL NC THIS MORNING. ALOFT...A WEAK
DISTURBANCES WITHIN THE BROAD SUBTROPICAL RIDGE IS MOVING OVER THE
CWA...WITH THE ASSOCIATED CIRRUS CURRENTLY EXITING THE NORTHERN
COASTAL PLAIN. BENEATH A STRONG AND DRY SUBSIDENCE INVERSION AT
900MB...INCREASINGLY VEERED LOW LEVEL FLOW IS BEGINNING TO ADVECT
MOISTURE INLAND. IR IMAGERY SHOWS STRATUS EXPANDING FROM COASTAL
CAROLINA NORTHWESTWARD INTO THE SOUTHERN COASTAL PLAIN AND
SANDHILLS. THE HRRR MOISTURE FIELDS...WHICH APPEAR TO HAVE A GOOD
HANDLE ON THIS CLOUD COVER...SHOW MOISTURE SPREADING NORTH THROUGH
THE PIEDMONT THIS MORNING. IF THE CLOUD COVER IS AS THICK AND
WIDESPREAD AS THE NAM AND RAP FORECAST SOUNDINGS SHOW....HIGHS WILL
BE A GOOD 5-7 DEGREES BELOW FULL SUN THICKNESS VALUES TODAY. PREFER
THE COOLER MET MOS BASED ON CURRENT TRENDS...51-58 WEST TO EAST.
OTHERWISE..NO SENSIBLE WEATHER IMPACTS TODAY AS MOISTURE IS MUCH TOO
SHALLOW AND THE MID LEVELS TOO DRY FOR ANY PRECIP.
TONIGHT...
CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE
RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS
ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE
WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS
MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING
SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD
LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE
LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD
BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42.
WEDNESDAY...
THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS
HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN
UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST
US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE
AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE
SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY
ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE
LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW
LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW
VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF
CLOUD COVER ON HEATING. HIGHS 61-66.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1240 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS
STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS
WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL
CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING
CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT
KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW
CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z.
DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS
AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG
SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF
MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED
OUT...BUT CONFIDENCE IS MUCH LOWER.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT)
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...SMITH
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 850 PM MONDAY...
TONIGHT:
HIGH PRESSURE WILL CONTINUE TO SHIFT EASTWARD OVERNIGHT KEEPING
SKIES MOSTLY CLEAR. CURRENT SATELLITE AND WATER VAPOR TRENDS SHOW
AN AREA OF HIGH LEVEL MOISTURE BRAINING SOME CLOUDS OVER UPSTATE
SOUTH CAROLINA THAT MAY AFFECT CENTRAL NC OVER THE NEXT SEVERAL
HOURS. ANY LINGERING CLOUDINESS ASIDE...LOW TEMPERATURE SHOULD BE
ABLE TO DROP INTO THE UPPER 20S IN MOST LOCATIONS TO NEAR 30 IN THE
SOUTH WHERE SOME MID LEVEL STRATUS MAY CREEP IN FROM THE SOUTHEAST
JUST BEFORE SUNRISE. FOR THE MOST PART DEWPOINT DEPRESSIONS SHOULD
BE LARGE ENOUGH TO KEEP FOG OR LOW STRATUS FROM FORMING BUT THERE IS
AN OUTSIDE CHANCE THAT IT COULD FORM AT KRWI DURING THE EARLY
MORNING HOURS. WINDS WILL BE LARGELY CALM OVERNIGHT BUT WILL
GRADUALLY SHIFT TO A SOUTHWESTERLY DIRECTION AS THE HIGH PUSHES OUT
TO SEA. -ELLIS
TUESDAY:
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA ALONG
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING ACROSS THE AREA IN THE SW
FLOW. NOT EXPECTING ANY PRECIP AS WE WILL HAVE A LOT OF DRY MID
LEVEL AIR AND NOT ENOUGH ISENTROPIC LIFT AND MOISTURE IN THE LOW
LEVELS. LOW LEVEL MOISTURE RETURN SHOULD ALLOW FOR AT LEAST PARTLY
SUNNY TO EVEN MOSTLY CLOUDY SKIES ACROSS A GOOD PORTION OF THE AREA
TUESDAY... WITH THE EARLIEST AND MOST CLOUDS ACROSS THE WEST AND
SOUTH/SOUTHWEST... WITH THE LEAST IN THE NORTHEAST. AFTERNOON LOW
LEVEL THICKNESS VALUES ARE PROGGED TO BE AROUND 15 METERS HIGHER
THAN TODAY. HOWEVER... THANKS TO THE INCREASE IN CLOUD COVER HIGH
TEMPS OVER MOST OF THE AREA WILL NOT BE ABLE TO REACH THEIR FULL SUN
HIGHS.... ESPECIALLY IN THE WEST... WHICH IS SHOWN IN THE
STATISTICAL GUIDANCE WELL. THUS... WILL GO WITH HIGH TEMPS RANGING
FROM THE LOWER 50S WEST TO UPPER 50S/NEAR 60 EAST/SOUTHEAST. -BSD
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS IF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1240 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS
STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS
WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL
CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING
CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT
KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW
CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z.
DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS
AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG
SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF
MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED
OUT...BUT CONFIDENCE IS MUCH LOWER.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT)
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BSD
NEAR TERM...ELLIS/BSD
SHORT TERM...KC
LONG TERM...KC
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1240 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 850 PM MONDAY...
TONIGHT:
HIGH PRESSURE WILL CONTINUE TO SHIFT EASTWARD OVERNIGHT KEEPING
SKIES MOSTLY CLEAR. CURRENT SATELLITE AND WATER VAPOR TRENDS SHOW
AN AREA OF HIGH LEVEL MOISTURE BRAINING SOME CLOUDS OVER UPSTATE
SOUTH CAROLINA THAT MAY AFFECT CENTRAL NC OVER THE NEXT SEVERAL
HOURS. ANY LINGERING CLOUDINESS ASIDE...LOW TEMPERATURE SHOULD BE
ABLE TO DROP INTO THE UPPER 20S IN MOST LOCATIONS TO NEAR 30 IN THE
SOUTH WHERE SOME MID LEVEL STRATUS MAY CREEP IN FROM THE SOUTHEAST
JUST BEFORE SUNRISE. FOR THE MOST PART DEWPOINT DEPRESSIONS SHOULD
BE LARGE ENOUGH TO KEEP FOG OR LOW STRATUS FROM FORMING BUT THERE IS
AN OUTSIDE CHANCE THAT IT COULD FORM AT KRWI DURING THE EARLY
MORNING HOURS. WINDS WILL BE LARGELY CALM OVERNIGHT BUT WILL
GRADUALLY SHIFT TO A SOUTHWESTERLY DIRECTION AS THE HIGH PUSHES OUT
TO SEA. -ELLIS
TUESDAY:
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA ALONG
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING ACROSS THE AREA IN THE SW
FLOW. NOT EXPECTING ANY PRECIP AS WE WILL HAVE A LOT OF DRY MID
LEVEL AIR AND NOT ENOUGH ISENTROPIC LIFT AND MOISTURE IN THE LOW
LEVELS. LOW LEVEL MOISTURE RETURN SHOULD ALLOW FOR AT LEAST PARTLY
SUNNY TO EVEN MOSTLY CLOUDY SKIES ACROSS A GOOD PORTION OF THE AREA
TUESDAY... WITH THE EARLIEST AND MOST CLOUDS ACROSS THE WEST AND
SOUTH/SOUTHWEST... WITH THE LEAST IN THE NORTHEAST. AFTERNOON LOW
LEVEL THICKNESS VALUES ARE PROGGED TO BE AROUND 15 METERS HIGHER
THAN TODAY. HOWEVER... THANKS TO THE INCREASE IN CLOUD COVER HIGH
TEMPS OVER MOST OF THE AREA WILL NOT BE ABLE TO REACH THEIR FULL SUN
HIGHS.... ESPECIALLY IN THE WEST... WHICH IS SHOWN IN THE
STATISTICAL GUIDANCE WELL. THUS... WILL GO WITH HIGH TEMPS RANGING
FROM THE LOWER 50S WEST TO UPPER 50S/NEAR 60 EAST/SOUTHEAST. -BSD
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...
ELONGATED AREA OF HIGH PRESSURE AT THE SURFACE EXTENDING WNW TO ESE
OVER NC THROUGH THE PERIOD. RETURN FLOW AROUND THE HIGH WILL ADVECT
MOISTURE INTO THE CAROLINAS FROM THE ATLANTIC. WILL LIKELY SEE AN
INCREASE IN LOW CLOUDS TUESDAY NIGHT. GOOD ISENTROPIC UPGLIDE SHOULD
YIELD SOME LOW STRATUS ACROSS CENTRAL NC WEDNESDAY MORNING. HIGH
CLOUDS WILL SPREAD EASTWARD ACROSS THE AREA AHEAD OF A LOW PRESSURE
SYSTEM TO THE WEST. THIS PART OF THE FORECAST SHOULD REMAIN MOSTLY
DRY...WITH THE CHANCE OF A FEW SPRINKLES ACROSS THE SOUTH THURSDAY
MORNING. EXPECT HIGHS ON WEDNESDAY IN THE LOW TO MID 60S...WITH LOWS
INCREASING FROM MID 30S TO NEAR 40 TUESDAY NIGHT TO THE LOW TO UPPER
40S WEDNESDAY NIGHT.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 310 PM MONDAY...
THURSDAY THROUGH SATURDAY NIGHT:
LOW PRESSURE OVER TX WEDNESDAY NIGHT WILL GET ABSORBED IN THE
LONGWAVE TROUGH AS IT MOVE NORTHEAST ON THURSDAY. GOOD INFLUX OF
GULF MOISTURE AHEAD OF THE SYSTEM WILL HELP GENERATE PRECIP AHEAD OF
IT. THE MAJORITY OF THE PRECIP WILL RIDE NE OVER THE H85 HIGH
MEANDERING OFF THE SC COAST. BEST CHANCES FOR PRECIP OVER CENTRAL NC
WILL BE A RESULT OF ISENTROPIC UPGLIDE FROM THE MOIST RETURN FLOW
AROUND THE HIGH. A HYBRID COLD AIR DAMMING EVENT IS LIKELY LATE THIS
WEEK AND POSSIBLY INTO THE WEEKEND AS THE SURFACE HIGH PRESSURE
BUILDS INTO THE NC PIEDMONT FROM THE NE...BEGINNING LATE THURSDAY.
THE FORECASTED PRECIP IN THE NORTHWEST THURSDAY AND FRIDAY WILL HELP
TO MOISTEN AND COOL THE LOW LEVELS AND LOCK IN THE COLD AIR. WITH
THE DAMMING IN PLACE AND THE WARM MOIST AIR EXPECTED TO OVERRUN THE
COOL STABLE LAYER IN THE NW...WILL LIKELY SEE AN EXTENDED PERIOD OF
OVERCAST SKIES...LIGHT RAIN IN THE FAVORED DAMMING REGION...AND A
STRONG GRADIENT IN TEMPERATURE FROM THE NW TO SE PORTION OF THE
AREA. THERE IS SIGNIFICANT UNCERTAINTY WITH REGARD TO WHEN THE CAD
WILL ERODE...WHICH WILL GREATLY IMPACT TEMPERATURES DURING THAT
TIME. AT THIS TIME...HAVE KEPT THE WEDGE OF COLD AIR IN THROUGH
SATURDAY. HIGH TEMPS ON THURSDAY SHOULD BE IN THE MID 50S TO LOW 60S
AND OVERNIGHT LOWS NEAR 40 IN THE NE TO UPPER 40S SW. WITH THE COLD
AIR IN PLACE ACROSS THE NW...CURRENTLY HAVE HIGHS ON FRIDAY IN THE
MID 50S NW TO MID 60S SE INCREASING ON SATURDAY TO MID 60S NW TO LOW
70S SE. OVERNIGHT LOWS FRIDAY AND SATURDAY NIGHTS IN THE MID 40S NW
TO LOW 50S SE.
SUNDAY THROUGH MONDAY:
ASSUMING THE WEDGE ERODES ON SATURDAY...WILL SEE IMPROVING WEATHER
CONDITIONS ON SUNDAY. MODELS CURRENTLY SHOW THE NEXT WEATHER SYSTEM
MOVING INTO THE WEST MONDAY MORNING...WITH THE BEST CHANCES FOR
PRECIP ACROSS THE AREA LATE MONDAY MORNING AND INTO THE AFTERNOON.
HIGH TEMPS ON SUNDAY ARE FORECAST IN THE UPPER 60S TO LOW 70S. WITH
INCREASING CLOUDINESS AND CHANCES FOR SHOWERS...HIGHS ON MONDAY MAY
BE A FEW DEGREES COOLER...LOW 60S TO NEAR 70. OVERNIGHT LOWS UPPER
40S TO LOW 50S.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1240 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS
STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS
WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL
CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING
CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT
KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW
CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z.
DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS
AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG
SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF
MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED
OUT...BUT CONFIDENCE IS MUCH LOWER.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT)
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BSD
NEAR TERM...ELLIS/BSD
SHORT TERM...KC
LONG TERM...KC
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1206 AM EST TUE JAN 8 2013
.SYNOPSIS...
A DEVELOPING OFFSHORE COASTAL TROUGH WILL PARALLEL THE CAROLINA
COAST THROUGH TUESDAY...THEN DISSIPATE ON WEDNESDAY. A STORM
SYSTEM...MOVING NORTHEAST OUT OF THE PLAIN STATES...WILL BRING A
WARM FRONT ACROSS THE AREA LATE WEEK. HIGH PRESSURE WILL BRING WARM
TEMPERATURES AND DRY WEATHER FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 1035 PM MONDAY...MID TO HIGH LEVEL CLOUDS CONTINUE TO EXPAND
NORTHWARD ACROSS THE FA THIS EVENING AND OVERNIGHT...WITH A LOW
DECK POSSIBLE ALONG THE IMMEDIATE COAST AS LATEST HRRR MODEL
INDICATES AN INVERTED SFC TROF TO DEVELOP JUST OFFSHORE LATE
TONIGHT. OVERNIGHT TEMPS/DEWPOINTS CONTINUE TO BE MASSAGED...MOSTLY
TOWARD THE UPWARD SIDE DUE TO INCREASING OPAQUE SKY COVER. WINDS
ACROSS THE INLAND COUNTIES WILL HAVE THE POTENTIAL TO DECOUPLE AS
THE CENTER OF THE SFC HIGH EXTENDS ACROSS THIS AREA. COULD OBSERVE
NEAR FREEZING READINGS IF RAD COOLING CONDITIONS PERSIST
THROUGH THE OVERNIGHT.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...AS WEDGE OF HIGH PRESSURE HANGS ON AT THE
SURFACE IN A WEDGE-LIKE SCENARIO THE MAIN FORECAST ISSUE ON TUES
SEEMS TO BE THE EXTENT OF CLOUD COVER THAT MANAGES TO DEVELOP. E TO
NE WINDS BENEATH WARM ADVECTION/SW FLOW AT 850 MB LEADS TO A NEARLY
ISOTHERMAL LAYER FROM VERY ROUGHLY 950-850MB WITH FAIRLY HIGH RH.
ABOVE THIS LAYER IS VERY DRY AIR ASSOCIATED WITH SUBSIDENCE
INVERSION. ACTUAL MIXING IS FORECAST TO BE QUITE SHALLOW SO THIS DRY
AIR MAY NOT COME TO BEAR TOO MUCH WITH RESPECT TO CLOUD COVER
OBSERVED AT THE SURFACE...I JUST WONDER IF GUIDANCE IS BRINGING IN
TOO MUCH MOISTURE OFF OF THE ATLANTIC. THE ACTUAL FRONTAL BAND
SHOULD NOT MAKE IT THIS FAR NORTH AND WEST AND GUIDANCE IS IN
FAIRLY GOOD AGREEMENT THAT LOW LEVEL ISENTROPIC UPGLIDE IS VERY
SLOW OR EVEN NOT FORECAST TO DEVELOP UNTIL NIGHTTIME. SHOW A GRADUAL
UPWARD TREND IN SKY COVER BUT WILL CAP VALUES NEAR UPPER RANGES OF
PARTLY CLOUDY SAVE FOR SOUTHERN ZONES WHICH WILL REGISTER MOSTLY
CLOUDY IN TEXT PRODUCTS IN ALL LIKELIHOOD. SMALL POPS HINTED AT IN
GUIDANCE SEEMS IMPLAUSIBLE DUE TO AFOREMENTIONED DRY AIR. DRIZZLE
SEEMS LIKE WORST CASE. BY WEDNESDAY THE HIGH SHOWS VERY LITTLE
MOVEMENT BUT WEAKENS SUFFICIENTLY TO NO LONGER IMPLY COOL AIR
WEDGING. MIXING IS FORECAST TO REMAIN QUITE SHALLOW AND SO SOME OF
THE LOW LEVEL WARM AIR ADVECTION MAY NOT BE REALIZED AT THE SURFACE
(ESPECIALLY IF THE CLOUD COVER CONTINUES TO INCREASE). BASED UPON
THIS AND SIMILAR CONCERN NOTED BY SOME NEIGHBORS HAVE TRIMMED WED
HIGHS A FEW DEGREES BELOW GUIDANCE. MOISTURE PROFILE A LITTLE DEEPER
IN FORECAST SOUNDINGS BUT RAIN CHANCES WILL STAY CAPPED AT SLIGHT
CHANCE IN THE ABSENCE OF ANY REAL FORCING MECHANISM.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...MAIN DETAILS OF THE SYNOPTIC PATTERN FOR THE
EXTENDED REMAIN IN PLACE THIS AFTERNOON AS A STRONG CLOSED LOW
WILL MOVE QUICKLY THROUGH THE MIDWEST AND SHEAR OUT. THE FLOW
BETWEEN THIS FEATURE AND AN ANOMALOUS RIDGE TO THE SOUTHEAST WILL
CREATE A VERY WARM AND PERSISTENT FLOW.
THE LOW...BEFORE SHEARING OUT AND FILLING IS 3-4 STAND DEVIATIONS
BELOW NORMAL AND THE RIDGE IS 1-2 ABOVE. 850MB TEMPERATURES OF 13-15
DEGREES C WILL ADVECT INTO THE AREA FOR THE WEEKEND. MEX GUIDANCE IS
ADVERTISING WIDESPREAD 70S FOR THE THIRD DAY IN A ROW AND THE
FORECAST HAS BEEN ADJUSTED UPWARD AS EVEN THE COOLER HPC NUMBERS ARE
MOSTLY IN THE 70S FOR THE WEEKEND. THE ONLY RECORD THAT APPEARS IN
JEOPARDY AT THIS TIME IS FLORENCE FOR SATURDAY WHICH IS 73 DEGREES.
THE KICKER SYSTEM...THE ONE THAT FORCES THE INITIAL DEEP LOW TO MOVE
OUT BEGINS TO IMPACT THE REGION MONDAY WITH INCREASED CLOUDINESS AND
SLIGHT CHANCE POPS HENCE...SLIGHTLY COOLER TEMPERATURES.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...CLOUDS WILL LOWER WITH TIME AND WILL FORECAST CEILINGS
LOWERING FROM VFR TO MVFR AT ALL THE TERMINALS THROUGH DAYBREAK AS A
COASTAL TROUGH CONTINUES TO DEVELOP. MOIST RETURN FLOW AROUND HIGH
PRESSURE CENTERED OFFSHORE WILL KEEP BKN TO AT TIMES OVC CONDITIONS
AFTER DAYBREAK AS WELL. CEILINGS ARE EXPECTED TO LIFT TO VFR 12-14Z.
EXTENDED OUTLOOK...POSSIBLE MVFR CIGS/VSBYS WEDNESDAY ASSOCIATED
WITH A COASTAL TROUGH. SLIGHT CHANCE OF SHOWERS WEDNESDAY AND
THURSDAY. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF MIDNIGHT TUESDAY...HEADLINED SMALL CRAFT SHOULD EXERCISE
CAUTION THROUGH 11 AM TUE. A DEVELOPING COASTAL TROUGH WAS
TIGHTENING THE PRESSURE GRADIENT ACROSS THE WATERS...RESULTING IN
WINDS OF NEAR 20 KT WITH GUSTS NEAR 25 KT. THESE HIGHER WINDS WERE
PRODUCING SEAS OF 4 TO 5 FT ACROSS THE MAJORITY OF THE OUTER WATERS.
THESE CONDITIONS ARE EXPECTED TO PERSIST THROUGH MUCH OF THE
MORNING. THE WIND DIRECTION WILL REMAIN NE OVERNIGHT AS THE TROUGH
REMAINS TO OUR E.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...WEDGE-LIKE HIGH PRESSURE IN PLACE ON TUESDAY TO
BRING A LIGHT NE FLOW...GENERALLY IN THE 10 TO 15 KT RANGE. SEAS 2
TO 3 FT IN A PREDOMINANT 5 SECOND WIND CHOP. ON WEDNESDAY THE HIGH
BOTH WEAKENS AND MOVES EVER SO SLIGHTLY TO THE N. WINDS MAY VEER TO
EASTERLY WHILE THEY DROP TO ABOUT 10 KT. THIS WILL CUT OUT THE 3 FT
SEAS AND MOST PLACES WILL BE CAPPED AT 2 FT. DOMINANT PERIOD LIKELY
STAYS ABOUT 5 OR 6 SECONDS BUT A VERY SMALL 10 SECOND EASTERLY SWELL
IS ALSO FORECAST.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 3 PM MONDAY...MAIN EVENT FOR THE MARINE COMMUNITY WILL BE THE
WIND SHIFT OCCURRING FRIDAY MORNING AS A WARM FRONT MOVES ACROSS.
CONFIDENCE IS NOT ALL THAT GREAT AT LEAST IN REGARDS TO TIMING AS
MEDIUM RANGE GUIDANCE HAS BEEN JUMPING AROUND SOMEWHAT. EXPECT A
GRADUAL VEERING FROM NORTHEAST THURSDAY AFTERNOON TO SOUTH BY FRIDAY
AT 1200 UTC. SPEEDS REMAIN MARGINAL WITH 10-15 KNOTS. EXPECT MORE
WESTERLY WINDS SATURDAY COURTESY OF A GLANCING SHOT FROM A BACKDOOR
FRONT. SIGNIFICANT SEAS LOOK FAIRLY CONSISTENT WITH THE WAVEWATCH
STILL A BIT ON THE HIGH SIDE. THERE COULD STILL BE A SCEC HEADLINE
ESPECIALLY EARLY BUT THE WIND SHIFT SHOULD PRECLUDE A SMALL CRAFT
ADVISORY WITH 3-5 FEET EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...DCH/RJD
SHORT TERM...MBB
LONG TERM...SHK
AVIATION...RJD/DL
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1103 PM CST MON JAN 7 2013
.DISCUSSION...
SEEING SOME PATCHY FOG ACROSS TYPICAL COOL SPOTS IN NORTHWEST IOWA
THIS EVENING. MODELS STILL SHOW AN INCREASE IN MID-HIGH CLOUDS OVER
NORTHERN HALF OF THE CWA THROUGH THE NIGHT...WITH SOME THIN CIRRUS
ACROSS THE SOUTH. NOT EXPECTING FOG TO GET TOO OUT OF HAND...BUT DID
ADD MENTION OF PATCHY DENSE FOG BASED ON VISIBILITY REPORTS FROM
SHELDON/SPENCER AREAS. SHELDON AWOS ALSO REPORTING DRIZZLE...BUT
CALL TO SHERIFF IN THAT AREA REVEALED ONLY SPOTTY FOG AND NO ICING.
HAVE MADE MINOR ADJUSTMENTS TO SOME HOURLY TEMPERATURES THROUGH THE
EVENING...BUT OVERALL LOWS SEEM REASONABLE AND SEE NO REASON FOR ANY
MAJOR CHANGES THERE AT THIS TIME. UPDATED GRIDS HAVE BEEN SENT.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
MAIN AVIATION CONCERN THIS PERIOD IS RESIDUAL LOW LEVEL MOISTURE
FROM MELTING SNOW...MAINLY IN SOUTHEAST PARTS OF THE AREA WHERE WEAK
WINDS AND MINIMAL SKY COVER ARE EXPECTED THROUGH THE EARLY MORNING.
HAVE ALREADY SEEN SPOTTY IFR-LIFR VISIBILITY/CEILINGS IN PARTS OF
NORTHWEST IOWA AND WITH FAVORABLE DRAINAGE WIND OUT OF THE MISSOURI
VALLEY INTO KSUX AIRPORT COULD BRING SIMILAR CONDITIONS TO THAT SITE
THROUGH SUNRISE. LIGHT SOUTHERLY WINDS WILL INCREASE A BIT AHEAD OF
BOUNDARY SET TO PUSH THROUGH THE REGION TUESDAY AFTERNOON/EVENING.
WINDS WILL INCREASE FURTHER BEHIND BOUNDARY...AND MODELS APPEAR TO
HANG ON TO TOO COOL SURFACE LAYER TEMPS AND DO NOT ALLOW FOR THE
BETTER MIXING THAT PROGGED SURFACE READINGS WOULD ALLOW...SO PUT IN
SOME WIND GUSTS DURING THE AFTERNOON EXCEEDING 25 KNOTS AROUND
KHON...AND CLOSE TO THRESHOLD FOR KFSD/KSUX A BIT LATER INTO THE
AFTERNOON. STRONG WINDS REMAIN JUST OFF THE SURFACE THROUGH THE
EVENING...AND WITH VERY SHALLOW INVERSION WILL HANG ONTO THE GUSTY
WINDS INTO EVENING.
&&
.PREV DISCUSSION.../ISSUED AT 343 PM CST/
MULTIPLE PLAYERS IN TODAY/S FORECAST FOR TONIGHT INTO TOMORROW.
CURRENTLY...MOSTLY CLEAR SKIES ACROSS THE AREA WITH A FEW HIGH
CLOUDS ACROSS CENTRAL SOUTH DAKOTA. THE SUNSHINE HAS PROMOTED SNOW
MELT...BUT WITH WEAK WINDS AND STRONG INVERSION...MOISTURE REMAINS
IN THE NEAR SURFACE LAYER. COULD SEE FOG DEVELOP OVERNIGHT
TONIGHT...BUT TRICKY TO PIN POINT WHERE EXACTLY. HRRR CONTINUES TO
SUGGEST THAT PATCHY FOG WILL BE POSSIBLY ACROSS THE NORTH...WHILE
NAM FOCUSES ON THE SOUTH AND EAST. HAVE SIDED CLOSER TO NAM...BUT
WITH WEAK WINDS...COULD GET RADIATIONAL FOG NEARLY ANYWHERE CLEAR
SKIES REMAIN FOR A FEW HOURS. AS MENTIONED IN THE MORNING
DISCUSSION...AMPLIFYING WAVE MOVING ACROSS THE AREA LATE TONIGHT
WITH UPPER LEVEL DIV Q INCREASING AFTER 06Z MAINLY ACROSS THE
NORTHERN HALF OF THE FORECAST AREA. WITH FAIRLY DRY AIR THROUGH THE
MID LEVELS OF THE ATMOSPHERE...AM NOT EXPECTING ANY PRECIPITATION
AND DROPPED MENTION OF SPRINKLES/FLURRIES FROM THE FORECAST. IF FOG
DEVELOPS IN THE SOUTHEAST...WILL NEED TO KEEP AN EYE ON DRIZZLE
POTENTIAL WITH WEAK LIFT IN THE LOW LEVELS OF THE ATMOSPHERE.
COLD FRONT IS POISED TO MOVE THROUGH THE AREA ON TUESDAY. SOUTHERLY
WINDS WILL BECOME WEST AND SOMEWHAT GUSTY BEHIND THE FRONT WITH
20-30 KNOTS OF FLOW AT 925 HPA. NOT MUCH IN THE WAY OF COLD AIR
ADVECTION BEHIND THE FRONT...AND WITH ONLY MEAGER PRESSURE RISES AND
STRONG INVERSION REMAINING ALOFT...WILL STRUGGLE TO GET A LOT OF THE
MOMENTUM DOWN THE SURFACE. STRONGEST WINDS WILL LIKELY BE ACROSS
THE NORTHERN EDGE OF THE FORECAST AREA WITH STRONGEST GRADIENT WINDS
THERE...BUT STILL LOOK TO REMAIN BELOW ADVISORY CRITERIA.
UPPER LEVEL TROUGH IS EXPECTED TO DIG ACROSS THE DESERT SOUTHWEST
MID WEEK...WHICH PUSHES THE RIDGE AXIS OVER THE FORECAST AREA ON
WEDNESDAY. EXPECT ANOTHER RELATIVELY MILD DAY WITH MOSTLY SUNNY
SKIES AND ABOVE NORMAL TEMPERATURES. EXPECT HIGHS TO REACH JUST
ABOVE FREEZING IN SOUTHWEST MINNESOTA AND ADJACENT AREAS...NUDGING
INTO THE UPPER 30S IN NORTHWEST IOWA. THE WARMEST READINGS WILL BE
FOUND IN SOUTH CENTRAL SOUTH DAKOTA WITH THE MID OR UPPER 40S IN
AREAS WHERE MUCH OF THE SNOWPACK HAS MELTED.
FOR THURSDAY...A CUT OFF LOW IS EXPECTED TO FORM IN THE SOUTHWEST
PLAINS AND TRACK NORTHEAST INTO THE NORTHERN GREAT LAKES EARLY
SATURDAY. SOME MODEL DIFFERENCES STILL EXIST...WITH THE ECMWF AND
GEM STILL FOLLOWING A SLOWER AND SLIGHTLY MORE SOUTHERLY TRACK. ALL
MODELS DO CLIP OUR SOUTHEASTERN COUNTIES AS THE SURFACE LOW TRACKS
INTO IOWA THURSDAY EVENING. TEMPERATURES WILL BE PARTICULARLY TRICKY
WITH READINGS EXPECTED TO RISE UP ABOVE FREEZING BY THE AFTERNOON.
WITH VERY WARM LOW LEVELS...EXPECT PRECIPITATION TO BE ENTIRELY
LIQUID FOR THIS SYSTEM...BUT WITH SURFACE READINGS POTENTIALLY BELOW
FREEZING IN THE MORNING AND AGAIN THURSDAY NIGHT...FREEZING RAIN
WILL ALSO BE POSSIBLE. BUT GIVEN THAT THESE TEMPERATURES WILL ONLY
BE A DEGREE OR TWO BELOW FREEZING...ICE ACCUMULATION DOES NOT LOOK
TO BE SIGNIFICANT. BUT WILL STILL CONTINUE TO MONITOR FOR ANY
CHANGES IN THIS OUTLOOK.
TEMPERATURES ON FRIDAY WILL LIKELY BE SOMEWHAT STEADY OR BEGIN TO
FALL IN THE AFTERNOON AS COOLER TEMPERATURES BEGIN TO FILTER INTO
THE AREA BEHIND THIS SYSTEM. THE BROAD POSITIVELY TILTED TROUGH
DIGGING ACROSS THE SOUTHWEST PUSHES INTO THE WESTERN PLAINS FRIDAY
EVENING...BRINGING THE NEXT POTENTIAL FOR WET WEATHER TO REGION
FRIDAY NIGHT AND SATURDAY. AGAIN...THE ECMWF IS A BIT SLOWER AND
SHOWS MORE OF A CLOSED UPPER LEVEL FEATURE. A SLIGHT CHANCE FOR SOME
LIGHT SNOW OR FLURRIES WILL BE POSSIBLE AHEAD OF THE MAIN WAVE ON
FRIDAY. THE DETAILS ARE STILL QUITE UNCERTAIN AT THIS POINT...BUT
THE GFS APPEARS TO TAKE THE BEST DYNAMICS WEST AND NORTH OF THE
FORECAST AREA...WHILE THE ECMWF HAS A BIT MORE ORGANIZATION WITH A
DECENT BAND OF MID LEVEL FRONTOGENESIS MOVING THROUGH THE FORECAST
AREA. WILL KEEP MENTION OF POPS AS A HIGH CHANCE FOR SOME LIGHT
SNOWFALL FRIDAY NIGHT AND SATURDAY. PRELIMINARY AMOUNTS LOOK LIKE A
FEW INCHES WOULD BE POSSIBLE ACROSS THE CWA.
THE LOW EXITS THE AREA SATURDAY NIGHT WITH A STRONGER SHOT OF COLD
AIR ADVECTION ARRIVING IN ITS WAKE. TEMPERATURES WILL BE MUCH COOLER
FOR THE START OF NEXT WEEK WITH HIGHS MAINLY IN THE TEENS AND LOWS
AROUND ZERO.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
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AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1046 AM EST TUE JAN 8 2013
.SYNOPSIS...
A WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION AND PREVAIL
THROUGH WEDNESDAY...WHILE A COASTAL TROUGH STRENGTHENS OFFSHORE. A
WEAK WARM FRONT WILL LIFT NORTH OF THE AREA THURSDAY AS A STORM
SYSTEM PASSES WELL TO THE WEST. ATLANTIC HIGH PRESSURE WILL THEN
PREVAIL INTO EARLY NEXT WEEK BEFORE A COLD FRONT APPROACHES FROM THE
WEST.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE THIS MORNING...SURFACE ANALYSIS SHOWS THE REGION SOLIDLY
WITHIN THE LOW LEVEL RIDGE EXTENDING FROM THE 1032 MB HIGH LOCATED
NEAR THE CHESAPEAKE. ALOFT...NEARLY ZONAL FLOW DOMINATES WITHIN
THE SLIGHTLY ANTICYCLONICALLY CURVED SW FLOW. THE MAIN FORECAST
ISSUES FOR TODAY REVOLVE AROUND THE EXPECTED INCREASING CLOUD
COVER AND THE POTENTIAL FOR SHOWER DEVELOPMENT OVER THE COASTAL
WATERS CLOSER TO THE OFFSHORE COASTAL TROUGH. CURRENT CLOUD COVER
IS PRIMARILY COMPRISED OF MID/HIGH LEVEL CLOUDS...WITH SOME
PATCHES OF LOWER OVERCAST SPREAD AROUND PORTIONS OF GA AND SC. I
HAVE SLOWED THE PROGRESSION OF TOTALLY OVERCAST SKIES AND RAISED
TEMPS A DEGREE OR SO BASED ON MORE SUNSHINE THAN ORIGINALLY
THOUGHT. THIS STILL KEEPS HIGHS IN THE LOW 60S...EXCEPT FOR UPPER
50S FAR INLAND. BUT MODELS STILL SHOW CONSIDERABLE LOW LEVEL
MOISTURE SO AT SOME POINT LATER TODAY AND INTO THE EVENING WE
SHOULD BEGIN TO SEE A SOLID BLANKET OF STRATUS START TO DEVELOP.
REGARDING THE COASTAL TROUGH...IT IS NOT VERY SHARPLY DEFINED AT
THIS POINT AND ANY RESULTING SHOWER ACTIVITY IS QUITE WEAK AND
LOCATED WELL OFFSHORE. RECENT RUNS OF THE RUC SHOW A BROADER
COASTAL TROF THROUGH THE DAY WITH LESS COVERAGE OF SHOWERS WITHIN
THE WEAKER LOW LEVEL CONVERGENCE. AS SUCH...I HAVE KEPT POPS IN
THE SLIGHT CHANCE RANGE AND LIMITED THEM TO JUST THE COASTAL
WATERS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...PRETTY MUCH THE SAME PATTERN WILL CONTINUE WITH INLAND
HIGH PRESSURE AND OFFSHORE LOW PRESSURE. EXPECT MOST OF THE
SHOWERS TO REMAIN OFFSHORE BUT COASTAL AREAS...ESPECIALLY ACROSS
SOUTHEAST GEORGIA...LOOK TO HAVE THE BEST SHOT AT SEEING A FEW.
WILL LIKELY SEE MORE IN THE WAY OF LOW CLOUDS AND SPRINKLES WITH
SOME FOG AS WELL. LOWS SHOULD RANGE FROM THE MID TO UPPER 40S
INLAND TO LOWER TO MID 50S ALONG THE COAST.
WEDNESDAY AND WEDNESDAY NIGHT...THERE IS INCREASING CONFIDENCE THAT
THE IN-SITU WEDGE OF HIGH PRESSURE WILL REMAIN ENTRENCHED OVER THE
AREA AS THE PARENT SURFACE HIGH SHIFTS OFF THE MID-ATLANTIC COAST
ALLOWING THE COASTAL TROUGH JUST OFFSHORE TO STRENGTHEN. ABUNDANT
LOW LEVEL MOISTURE AND MODEST ISENTROPIC ASCENT WILL BE ENOUGH TO
KEEP SKIES NEARLY OVERCAST WITH RATHER LOW CEILINGS EXPECTED. THE
BEST FOCUS FOR ANY SHOWERS WILL MAINLY BE NEAR THE COASTAL TROUGH
DUE TO ENHANCED LOW LEVEL CONVERGENCE...BUT ISENTROPIC ASCENT WILL
SUPPORT ADDITIONAL LIGHT PRECIPITATION INLAND AS WELL WHICH WILL
ONLY HELP TO REINFORCE THE WEDGE. THE FORECAST WILL INDICATE A
CHANCE OF SHOWERS FOR MOST OF THE AREA BY WEDNESDAY AFTERNOON...THEN
A SLIGHT CHANCE OF SHOWERS WEDNESDAY NIGHT. ALSO EXPECT AREAS OF FOG
AND POSSIBLY DRIZZLE TO TO FORM WEDNESDAY NIGHT...AND THE FOG COULD
BECOME DENSE AT TIMES.
DESPITE MOST OF THE GUIDANCE BEING ON BOARD INDICATING LOW CEILINGS
AND NORTH/NORTHEASTERLY WINDS ON WEDNESDAY...THEY ALL SHOW HIGHS
REACHING INTO AT LEAST THE LOWER 70S WITH LOW LEVEL THICKNESS VALUES
EVEN WARMER THAN THAT. THIS IS HARD TO BELIEVE GIVEN THIS
SCENARIO...AND FEEL THE MODELS MAY NOT HAVE A GOOD HANDLE ON THE LOW
LEVEL ENVIRONMENT. WILL THEREFORE CONTINUE TO FORECAST HIGHS ON
WEDNESDAY WELL BELOW GUIDANCE...RANGING FROM THE MID 60S INLAND TO
NEAR 70 ACROSS NORTH COASTAL GEORGIA AND NEAR THE ALTAMAHA RIVER.
THURSDAY AND THURSDAY NIGHT...A COMBINATION OF A WARM FRONT AND
COASTAL TROUGH WILL BEGIN TO LIFT NORTHWARD AS UPPER LEVEL RIDGING
BUILDS OVER THE SOUTHEASTERN U.S. IN RESPONSE TO A STORM SYSTEM
LIFTING NORTHEAST INTO THE MISSISSIPPI VALLEY. THIS WILL ALLOW FOR
THE GRADUAL EROSION OF THE IN-SITU WEDGE. LOW CLOUDS AND FOG WILL
LINGER INTO AT LEAST THE MORNING HOURS...BEFORE SOME PARTIAL
CLEARING OCCURS LATER IN THE DAY. SEA FOG COULD FORM JUST OFF THE
COAST AND POSSIBLY ADVECT INLAND AT JUST ABOUT ANY TIME. THERE COULD
BE SOME ISOLATED TO SCATTERED SHOWERS AROUND...WITH THE GREATEST
COVERAGE ACROSS SOUTHEAST SOUTH CAROLINA IN CLOSER PROXIMITY TO THE
WARM FRONT MAINLY DURING THE DAY THURSDAY. THE BUILDING RIDGE AND
LIFTING WARM FRONT WILL ALLOW TEMPERATURES TO SOAR TO HIGHS IN THE
LOWER 70S ON THURSDAY...WITH ANOTHER WARM NIGHT EXPECTED THURSDAY
NIGHT.
FRIDAY...A PASSING SHORT WAVE DISTURBANCE WILL CAUSE THE UPPER RIDGE
TO FLATTEN SOME IN THE MORNING...BUT A DEEP SOUTHERLY FLOW AROUND
ATLANTIC HIGH PRESSURE WILL ALLOW FOR TEMPERATURES TO CONTINUE TO
CLIMB. HIGHS ARE FORECAST TO BE IN THE MID TO UPPER 70S ACROSS MUCH
OF THE AREA AWAY FROM THE COAST. SUFFICIENT LOW LEVEL MOISTURE AND
THE PASSAGE OF THE SHORT WAVE COULD SUPPORT ISOLATED SHOWERS ACROSS
THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MEDIUM RANGE GUIDANCE IS IN EXCELLENT AGREEMENT THROUGH THE WEEKEND
INDICATING A STRONG UPPER LEVEL RIDGE OVER THE REGION...WHILE
ATLANTIC HIGH PRESSURE PREVAILS AT THE SURFACE. STRONG SUBSIDENCE
AND A LACK OF DEEP MOISTURE WILL KEEP CONDITIONS RAIN-FREE. THE
BIGGER STORY WILL BE THE UNSEASONABLY WARM...IF NOT HOT FOR THIS
TIME OF YEAR...TEMPERATURES. HIGHS OVER THE WEEKEND SHOULD BE WELL
INTO THE UPPER 70S AWAY FROM THE COAST...WITH SOME 80 DEGREE
READINGS CERTAINLY POSSIBLE. THESE HIGHS WILL BE APPROACHING RECORD
TERRITORY.
GUIDANCE BEGINS TO DIVERGE A BIT EARLY NEXT WEEK WITH RESPECT TO THE
TIMING OF A COLD FRONT AS IT APPROACHES FROM THE WEST AND SLOWS AS
IT ENCOUNTERS THE UPPER RIDGE. THE FORECAST WILL INDICATE A SLIGHT
CHANCE OF SHOWERS ON MONDAY WITH PROBABILITIES INCREASING INTO THE
CHANCE CATEGORY ON TUESDAY AS THE FRONT NEARS. TEMPERATURES SHOULD
MODERATE SOME...BUT OVERALL REMAIN WELL ABOVE NORMAL.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
A WEDGE OF HIGH PRESSURE WILL BECOME BETTER ESTABLISHED TODAY AS A
COASTAL TROUGH STRENGTHENS OFFSHORE. THIS WILL ALLOW ABUNDANT LOW
LEVEL MOISTURE TO BECOME TRAPPED BENEATH AN INVERSION...RESULTING
IN STRATUS THROUGH MOST OF THE FORECAST PERIOD. CEILINGS SHOULD
BORDER THE VFR AND MVFR CATEGORIES FOR MOST OF THE AFTERNOON...BUT
PREFER TO KEEP IT PREVAILING VFR UNTIL THERE IS A BETTER
INDICATION TO WHEN LOWER CEILINGS WILL DEVELOP. THE POTENTIAL FOR
LOWER CEILINGS WILL INCREASE THIS EVENING AS THE INVERSION
LOWERS. WILL INDICATE MVFR CEILINGS AT BOTH TERMINALS AFTER ABOUT
23Z...WITH IFR CEILINGS AT KSAV AFTER 07Z. PATCHY FOG COULD ALSO
REDUCE VISIBILITIES OVERNIGHT.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS ARE LIKELY INTO
THURSDAY. FOG COULD ALSO REDUCE VISIBILITIES TO MVFR OR LOWER LEVELS
AT TIMES DURING THE LATE NIGHT/EARLY MORNING HOURS INTO THE WEEKEND.
&&
.MARINE...
TODAY AND TONIGHT...A TROUGH OF LOW PRESSURE IS EXPECTED TO REMAIN
OVER THE LOCAL WATERS THROUGH TONIGHT WHICH WILL LEAD TO A VARYING
WIND DIRECTION/SPEED FORECAST AS THE WESTERN SIDE OF THE TROUGH
NEAR THE COAST WILL SEE ENHANCED NORTHEAST WINDS WHILE THE EASTERN
SIDE SEES LIGHTER EASTERLY WINDS. DO NOT ANTICIPATE ANY
HEADLINES OTHER THAN THE EXISTING ADVISORY FOR THE WATERS BEYOND
20 NM UNTIL EARLY AFTERNOON WHERE SEAS REMAIN ELEVATED IN THE
NORTHEAST FLOW. MARINERS SHOULD ALSO BE ALERT FOR SOME FOG
DEVELOPING LATE TONIGHT...ESPECIALLY ACROSS THE COOLER NEARSHORE
WATERS ALONG THE GEORGIA COAST...AS A MORE HUMID AIRMASS SPREADS
INTO THE AREA.
WEDNESDAY THROUGH SUNDAY...A COASTAL TROUGH WILL PERSIST OVER OR
NEAR THE WATERS ON WEDNESDAY...BEFORE LIFTING NORTH AS A WARM FRONT
ON THURSDAY. THERE COULD BE SOME PINCHING OF THE GRADIENT EARLY
WEDNESDAY KEEPING THE NORTHEAST FLOW SOMEWHAT ELEVATED...HOWEVER THE
GRADIENT WILL WEAKEN AS THE FLOW VEERS TO THE SOUTHEAST THROUGH
THURSDAY. A SOUTH-SOUTHWEST FLOW WILL THEN PREVAIL THROUGH THE
WEEKEND DUE TO THE INFLUENCE OF ATLANTIC HIGH PRESSURE. WINDS ARE
EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH THE
PERIOD...ALTHOUGH A FAVORABLE FETCH COULD BUILD SEAS TO 6 FT OVER A
PORTION OF THE OUTER GEORGIA WATERS LATE THURSDAY AND FRIDAY. THERE
IS A RISK OF SEA FOG OVER THE COOL NEARSHORE WATERS BEGINNING
WEDNESDAY ACROSS THE GEORGIA NEARSHORE WATERS AND SPREADING NORTH LATE
IN THE WEEK AND POSSIBLY INTO THE WEEKEND...AS A WARM AND MORE
HUMID AIRMASS ADVECTS INTO THE AREA.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR AMZ374.
&&
$$
NEAR TERM...BSH
SHORT TERM...RJB/JAQ
LONG TERM...JAQ
AVIATION...JAQ
MARINE...RJB/JAQ
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
535 AM CST TUE JAN 8 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
In the short term, concerns are focused on temperatures along with
rainfall potential Wednesday night into Thursday. Early this morning,
a large upper level low continued to spin over northern Mexico as a
progressive upper trough crosses the Northern Plains. Due to an
enhanced area of cirrus moving across the region, temperatures have
remained in the 30s in most locations.
Today: Upper troughing in the Northern Plains will establish weak
surface troughing across portions of east central Kansas through
northwestern Missouri. Winds ahead of this surface trough will again
become breezy by afternoon, with abnormally warm 950:850 temperatures
supporting temperatures into the 50s in many areas. Again, have
followed short term RAP guidance for temperatures this afternoon
which did an excellent job on Monday. The warmest temperatures may
pool just ahead of this surface trough where readings could spike
into the middle 50s.
Tonight: The weak surface trough will move into the region washing
out as it does so. A bit less cirrus may be possible given the
northwesterly upper level flow. The resultant temperatures will fall
into the upper 20s in most locations.
Wednesday: The upper level low over northern Mexico will finally
become dislodged as troughing enters the Pacific Northwest. Locally,
an elongated west to east ridge of high pressure will remain over the
area throughout the daytime hours, keeping winds light and variable.
Temperatures, given the weak boundary and low level flow, will not be
quite as warm as on Tuesday but should still climb near 50.
Wednesday night: The upper level low will quickly begin to surge
north by Wednesday evening with strong low-level moisture advection
headed into the area. Showers and even embedded thunderstorms will
overspread the area through the overnight hours. Models in reasonable
agreement (less the NAM) that rain will reach the Interstate 70
corridor by midnight and northern Missouri by daybreak.
Thursday: Tricky forecast as models indicate the deep upper low will
lift across the CWA during the daytime hours. Rain should quickly
lift northward in the morning, replaced with low cloud cover and
periods of showers/drizzle. Temperatures will be rather difficult and
highly dependent on the track of surface low pressure and surge of
warm air ahead of the surface low. Model guidance suggests a weak
surface low tracking north along with the upper low through eastern
Kansas by Thursday afternoon. NAM is the most aggressive bringing
near 60 degree readings into the CWA, but it is also the deepest and
most progressive solution of all guidance. Prefer the weaker
solutions of the GFS/SREF which still bring low 50s by the late
afternoon hours.
Dux
Medium Range (Friday through Monday)...
The medium range should start out very warm especially for the
climatologically coldest week of the year for Kansas City (January
10-17). With 850mb temps between 12C-14C, if we can mix out enough,
temperatures could easily range into the mid 50s to mid 60s.
However, those warm temperatures will be short-lived as a cold front
is forced into the forecast area Friday night in association with a
broad and deep upper level trough that will be traversing the
Rockies. This frontal passage looks to be dry as models are in good
agreement that the best moisture transport is south and east of the
forecast area. As such have lowered chance POPs inherited by the
initialization to silent slight chance POPs for Saturday. The main
effect of this cold front will be the marked change in temperatures.
High temperatures across the CWA Saturday will experience a 20
degree range from near 30 across northern Missouri where cold air
advection will be ongoing by day break...to near 50 across central
Missouri where cold air doesn`t begin to advect in until later in
the day. The upper level trough moves through the area on Sunday as
high pressure builds in at the surface with highs in the mid 20s to
lower 30s. Surface high pressure strengths over the area on Monday
and with abundant sunshine highs will return to near normal for the
coldest climatological week of the year with highs in the 30s.
73
&&
.AVIATION...
For the 12Z TAFs...conditions will remain VFR through the TAF period
with just cirrus expected through the day before clearing skies
tonight. Winds out of the south this morning around 10kts will veer
to the southwest this afternoon. A weak surface trough will move
through the terminals tonight veering winds to the west at MCI while
winds and MKC and STJ become light and variable.
73
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1016 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 305 AM TUESDAY...
REST OF TODAY:
SOUTHWEST FLOW ALOFT WILL PREVAIL TODAY...DOWNSTREAM OF A POTENT
UPPER LEVEL LOW MEANDERING EASTWARD ACROSS NORTHERN MEXICO. SMALL
AMPLITUDE DISTURBANCES WILL PROGRESS INTO THE CAROLINAS VIA SW FLOW
ALOFT THIS AFTERNOON...THOUGH NO APPRECIABLE DPVA IS ANTICIPATED. A
RELATIVELY WEAK 925-850 MB RETURN FLOW IS IN PLACE TODAY...ON THE
WESTERN PERIPHERY OF A LOW-LEVEL RIDGE CENTERED JUST OFFSHORE IN THE
ATLANTIC. AT THE SURFACE...LITTLE OR NO ADVECTION WILL OCCUR IN THE
PRESENCE OF A SFC RIDGE AXIS EXTENDING NORTHEAST FROM UPSTATE SC TO
SOUTHEAST VA. BROKEN TO OVERCAST LOW-LEVEL CLOUD COVER THIS MORNING
MAY PERSIST INTO THE AFTERNOON IN ASSOC/W LOW-LEVEL WARM
ADVECTION...ESP OVER THE NORTHERN PIEDMONT AND NE COASTAL PLAIN.
UNCERTAINTY IN CLOUD COVER AND RESULTING TEMPERATURES ARE THE
PRIMARY FCST PROBLEM. GIVEN CURRENT OBS/SAT IMAGERY AND REASONABLE
FORCING FOR CLOUD COVER TO PERSIST THROUGH MUCH OF DIURNAL
HEATING...HAVE OPTED TO LOWER HIGH TEMPS A FEW DEGREES...RANGING
FROM 50-54F (WARMEST FAR S/SE AND COOLEST N/NE). THOUGH LOW-LEVEL
FORCING SHOULD BE SUFFICIENT TO SUPPORT BROKEN TO OVERCAST CLOUD
COVER...OVERALL FORCING AND MOISTURE WILL BE INSUFFICIENT TO SUPPORT
PRECIPITATION. -VINCENT
TONIGHT...
CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE
RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS
ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE
WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS
MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING
SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD
LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE
LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD
BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42.
WEDNESDAY...
THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS
HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN
UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST
US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE
AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE
SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY
ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE
LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW
LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW
VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF
CLOUD COVER ON HEATING. HIGHS 61-66.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 645 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATOCU HAS SPREAD FROM SC NORTH ACROSS ALMOST ALL OF
CENTRAL NC. CEILINGS GENERALLY VARY FROM 5000FT NORTH TO 3000FT
SOUTH. BASED ON SATELLITE TRENDS AND HRRR MODEL MOISTURE
FIELDS...MVFR CEILINGS ARE MOSTLY LIKELY IN THE NEXT 3-6 HOURS AT
KFAY/KGSO/KINT. MVFR CEILINGS CANNOT BE RULED OUT AT KRDU AND/OR
KRWI..BUT CONFIDENCE IS MUCH LOWER AT THESE SITES. WHILE SOME
IMPROVEMENT IS FORECAST THIS AFTERNOON...THIS MOISTURE IS TRAPPED
BENEATH A STRONG SUBSIDENCE INVERSION LOCATED NEAR 5000FT...SO
CEILINGS ARE LIKELY TO REMAIN NEAR MVFR LEVELS THROUGHOUT THE DAY.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT).
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...VINCENT/SMITH
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
952 AM EST TUE JAN 8 2013
.SYNOPSIS...
A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF
HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST
OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN
CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE
UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM TUESDAY...HIGH PRESSURE ALONG THE MID-ATLANTIC
COAST AND A WEAK COASTAL TROUGH ROUGHLY 30-40 MILES OFFSHORE ARE
PRODUCING A COOL NORTHEAST WIND ACROSS THE EASTERN CAROLINAS.
SATELLITE SHOWS LOW AND MID-LEVEL CLOUD COVER ASSOCIATED WITH MOIST
ATLANTIC AIR OVERRIDING THE SHALLOW COLD AIRMASS INLAND. THERE ARE
SOME SIZABLE HOLES IN THESE CLOUD DECKS MAINLY ACROSS EASTERN SOUTH
CAROLINA...AND THIS IS COMPLICATING OUR FORECAST FOR TODAY.
CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS
RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND
HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN
FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF
OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND
LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE
CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE
COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE
CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA
EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN
MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY.
ELSEWHERE...MID 50S SHOULD PREDOMINATE.
RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF
STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND.
THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY
DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS
GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE
PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE
RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST.
MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS
MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A
SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH
MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP
THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND
SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH
WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH
THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A
BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS
THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN
RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER
AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE
SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT
AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR
THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL
LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS
INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND
HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP
HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS
WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE
GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD
AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS.
TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA
AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE
BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL
AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA.
EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR
ABOVE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS
UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY
FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE
CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM
AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE
SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE
EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF
THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID
LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE
SOME CLOUDS THROUGH THE PERIOD.
H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE
WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT
WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON
HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR
THIS TIME OF YEAR...IN THE MID 50S.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...VFR/MVFR CIGS ACROSS THE AREA THIS MORNING AS SATELLITE
IMAGERY DEPICTS PLENTY OF LOW-LEVEL CLOUD COVER ASSOCIATED WITH A
COASTAL TROUGH. MOIST RETURN FLOW AROUND THE HIGH PRESSURE CENTERED
OFFSHORE WILL KEEP THE LOW CLOUDS AROUND THROUGH THIS TAF PERIOD. IT
APPEARS THAT LOW VFR CIGS WILL BE MOST PREVALENT ACROSS THE AREA
TODAY...ALTHOUGH SOME MVFR CIGS ARE POSSIBLE AS WELL. COULD SEE SOME
ISOLATED DRIZZLE ALONG THE COAST...BUT DECIDED IT WAS NOT WORTH
MENTIONING IN TAFS. EXPECT EAST WINDS AOB 8 KNOTS TODAY...BECOMING
LIGHT/CALM OVERNIGHT. MODEL SOUNDINGS AND GUIDANCE BOTH SUPPORT A
FOG/STRATUS EVENT OVERNIGHT WITH ABUNDANT LOW-LEVEL MOISTURE IN
PLACE ACROSS THE REGION. INCLUDED MVFR CIGS/VSBYS AFTER MIDNIGHT AT
ALL TERMINALS...AND IFR CONDITIONS COULD DEVELOP TOWARDS THE END OF
THE TAF PERIOD.
EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS WEDNESDAY AND THURSDAY.
SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO THURSDAY. VFR
DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM TUESDAY...BASED ON DATA FROM THE FRYING PAN SHOALS BUOY
SHOWING A SOUTHEAST WIND AND 66 DEGREE AIR TEMPERATURES...THE
COASTAL TROUGH LIES JUST TO THEIR WEST. ALL OTHER BUOY AND COASTAL
LOCATIONS HAVE MUCH COLDER AIR TEMPERATURES WITH NORTH TO NORTHEAST
WINDS. MODEL CONSENSUS IS THIS TROUGH SHOULD WEAKEN THIS AFTERNOON
AND ESPECIALLY TONIGHT AS THE HIGH ALONG THE MID-ATLANTIC COAST
NUDGES BACK TO THE SOUTH. RADAR SHOWS SOME PATCHY LIGHT RAIN JUST
EAST OF CAPE FEAR CURRENTLY. THIS PRECIPITATION SHOULD MOVE SLOWLY
NORTH THIS MORNING POTENTIALLY AFFECTING THE COASTAL WATERS NEAR
CAROLINA BEACH BEFORE DISSIPATING THIS AFTERNOON.
THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS
DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15
KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE
FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH
BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS
THROUGH 11 AM.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS
HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE
LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND
TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO
AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH
AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL
BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL
RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO
FRI.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE
SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH
PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL
GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO
10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON
FRI DOWN TO 2 TO 3 FT BY SAT NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
645 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 305 AM TUESDAY...
TODAY...
A 1030MB SURFACE HIGH CENTERED OVER THE VA TIDEWATER AREA EXTENDS
SOUTHWEST ACROSS CENTRAL NC THIS MORNING. ALOFT...A WEAK
DISTURBANCES WITHIN THE BROAD SUBTROPICAL RIDGE IS MOVING OVER THE
CWA...WITH THE ASSOCIATED CIRRUS CURRENTLY EXITING THE NORTHERN
COASTAL PLAIN. BENEATH A STRONG AND DRY SUBSIDENCE INVERSION AT
900MB...INCREASINGLY VEERED LOW LEVEL FLOW IS BEGINNING TO ADVECT
MOISTURE INLAND. IR IMAGERY SHOWS STRATUS EXPANDING FROM COASTAL
CAROLINA NORTHWESTWARD INTO THE SOUTHERN COASTAL PLAIN AND
SANDHILLS. THE HRRR MOISTURE FIELDS...WHICH APPEAR TO HAVE A GOOD
HANDLE ON THIS CLOUD COVER...SHOW MOISTURE SPREADING NORTH THROUGH
THE PIEDMONT THIS MORNING. IF THE CLOUD COVER IS AS THICK AND
WIDESPREAD AS THE NAM AND RAP FORECAST SOUNDINGS SHOW....HIGHS WILL
BE A GOOD 5-7 DEGREES BELOW FULL SUN THICKNESS VALUES TODAY. PREFER
THE COOLER MET MOS BASED ON CURRENT TRENDS...51-58 WEST TO EAST.
OTHERWISE..NO SENSIBLE WEATHER IMPACTS TODAY AS MOISTURE IS MUCH TOO
SHALLOW AND THE MID LEVELS TOO DRY FOR ANY PRECIP.
TONIGHT...
CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE
RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS
ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE
WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS
MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING
SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD
LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE
LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD
BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42.
WEDNESDAY...
THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS
HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN
UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST
US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE
AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE
SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY
ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE
LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW
LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW
VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF
CLOUD COVER ON HEATING. HIGHS 61-66.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 645 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATOCU HAS SPREAD FROM SC NORTH ACROSS ALMOST ALL OF
CENTRAL NC. CEILINGS GENERALLY VARY FROM 5000FT NORTH TO 3000FT
SOUTH. BASED ON SATELLITE TRENDS AND HRRR MODEL MOISTURE
FIELDS...MVFR CEILINGS ARE MOSTLY LIKELY IN THE NEXT 3-6 HOURS AT
KFAY/KGSO/KINT. MVFR CEILINGS CANNOT BE RULED OUT AT KRDU AND/OR
KRWI..BUT CONFIDENCE IS MUCH LOWER AT THESE SITES. WHILE SOME
IMPROVEMENT IS FORECAST THIS AFTERNOON...THIS MOISTURE IS TRAPPED
BENEATH A STRONG SUBSIDENCE INVERSION LOCATED NEAR 5000FT...SO
CEILINGS ARE LIKELY TO REMAIN NEAR MVFR LEVELS THROUGHOUT THE DAY.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT).
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...SMITH
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1006 AM MST TUE JAN 8 2013
.UPDATE...
&&
.SHORT TERM...MID LEVEL SHORT WAVE MOVING ACROSS EASTERN COLORADO
AT THIS TIME. WEAK SUBSIDENCE BEHIND WAVE ALONG WITH CROSS
MOUNTAIN FLOW OF 35 KTS COMBINED TO PRODUCE GUSTS AROUND 50 MPH
ALONG THE FOOTHILLS OF BOULDER AND JEFFERSON COUNTIES WITH THE
GJT-DEN 1500M PRESSURE GRADIENT AROUND 10.21 MB. WINDS STILL
EXPECTED TO DECREASE BY THE AFTERNOON AS NORTHWEST FLOW ALOFT
WEAKENS AND CROSS MOUNTAIN FLOW DECREASES TO AROUND 20 KTS.
CURRENT FORECAST TRENDS OF DECREASING WINDS STILL LOOKING
REASONABLE. A FEW LIGHT SNOW SHOWERS STILL POSSIBLE ALONG WEST
FACING SLOPES OF THE GORE AND PARK RANGES AS RAP CROSS SECTIONS
KEEP SOME MOISTURE TRAPPED IN THAT AREA. OTHERWISE...CLOUDS TO BE
ON THE DECREASE AS SUBSIDENCE AND DRIER AIR DOMINATES.
TEMPERATURES SLIGHTLY COOLER TODAY AS COLD AIR ADVECTION SPREADS
OVER AREA. CURRENT TEMPERATURE GRIDS STILL SEEM REASONABLE.
PERSISTANT SURFACE BASED INVERSIONS TO KEEP MOUNTAIN VALLEYS QUITE
COLD...ESPECIALLY OVERNIGHT.
.AVIATION...SOUTHWEST TO WEST WINDS ACROSS AREA AIRPORTS AT THIS
TIME. LATEST RAP AND HRRR INDICATING WINDS TO WEAKEN AND GO
CLOCKWISE DURING THE AFTERNOON...WITH NORTHEAST TO EAST WINDS AT
DEN AND APA. WINDS SHOULD REMAIN MORE NORTHWEST AT BJC. SPEEDS
SHOULD REMAIN BELOW 10 KTS...THOUGH SOME GUSTS TO 20 KTS WILL BE
POSSIBLE AT BJC. WILL BE MAKING ADJUSTMENTS TO THE DIRECTION TO
FOLLOW THE RAP/HRRR SOLUTIONS. VFR TO PREVAIL WITH CEILINGS ABOVE
10000 FEET.
&&
.PREV DISCUSSION... /ISSUED 355 AM MST TUE JAN 8 2013/
SHORT TERM...A COUPLE MID/HIGH LEVEL CLOUD BANDS PASSING OVER
THE FORECAST AREA AT THIS HOUR ASSOCIATED WITH A PASSING
SHORTWAVE TROUGH. NEXT FEW HOURS SHOULD SEE NORTHWESTERLY WINDS
ALOFT INCREASING WITH COLD ADVECTION. MODEL CROSS SECTIONS
INDICATE A 30-35 KT WEST-NORTHWEST MTN TOP WIND COMPONENT NOW
THROUGH 15Z THIS MORNING. COULD SEE GUSTY WESTERLY SFC WINDS OF
25-35 KTS DEVELOPING IN THE NEXT HOUR OR SO ON THE RIDGETOPS AND
EAST SLOPES OF THE FRONT RANGE. AREAS ALONG THE BASE OF THE
FOOTHILLS IN NRN JEFFERSON...BOULDER AND LARIMER COUNTIES COULD
ALSO SEE OCCASIONAL GUSTS OF 25-30 KTS THRU 15Z THIS MORNING. DO
NOT SEE MUCH IF ANY PRECIPITATION WITH THIS PASSING DISTURBANCE
AS THE SUB-CLOUD LAYER APPEARS QUITE DRY. LATER THIS MORNING
WITH THE TROUGH EXITING THE AREA...SHOULD SEE CLEARING AS WELL AS
A DECREASE IN WIND SPEEDS WITH THE FLOW ALOFT WEAKENING AND WITH
THE CROSS STATE PRESSURE GRADIENT RELAXING. LOOKING FOR HIGH
TEMPERATURES TODAY TO GENERALLY BE 2-3C ABOVE AVERAGE FOR THE
DATE...WITH MID 40S-LOWER 50S ON THE PLAINS...AND 20S-30S IN THE
HIGH COUNTRY. ALTHOUGH LOW LYING AREA IN THE HIGH MOUNTAIN
VALLEYS SUCH AS ALONG THE COLORADO RIVER IN MIDDLE PARK AND AROUND
ANTERO AND ELEVENMILE CANYON RESERVOIRS IN SOUTH PARK WILL ONCE
AGAIN STRUGGLE TO CLIMB ABOVE THE SINGLE DIGITS DUE TO A STRONG
AND PERSISTENT SFC BASED TEMPERATURE INVERSION. OVERNIGHT
NORTHWEST FLOW ALOFT IN THE EVENING TURNS ZONAL/WESTERLY AFTER
MIDNIGHT WITH HEIGHT RISES ACROSS UTAH AND WESTERN COLORADO.
TEMPERATURES TONIGHT WILL BE SLIGHTLY WARMER ON THE PLAINS AND AT
HIGHER ELEVATIONS. ALTHOUGH A STRONG NOCTURNAL INVERSION WILL
ONCE AGAIN RESULT IN ANOTHER NIGHT OF BITTER COLD TEMPERATURES...
AS MUCH AS 15 TO 20 F BELOW ZERO...FOR THOSE SAME MTN VALLEY
LOCATIONS MENTIONED ABOVE.
LONG TERM...WLY FLOW ALOFT WILL BE OVER THE AREA ON WED AND THEN
BECOME MORE SWLY ON THU AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE
WRN US. OVERALL IT SHOULD BE DRY OVER THE RGN THRU THU WITH ABV
NORMAL TEMPS ACROSS NERN CO. HIGHS BOTH DAYS SHOULD BE IN THE 50S
ALONG THE FRONT RANGE WITH SLIGHTLY COOLER READINGS OVER THE FAR
NERN PLAINS.
FOR FRI INTO FRI NIGHT BOTH THE GFS AND ECMWF WANT TO MOVE THE
UPPER LEVEL TROUGH OVER THE WRN US QUICKLY EASTWARD ACROSS THE
AREA. SOME OF THE ENSEMBLE MEMBERS ARE SLOWER BUT FOR NOW WILL
TREND FCST WITH FASTER SOLUTION. MEANWHILE THERE WILL BE A STG
CDFNT MOVING INTO NERN CO DURING THE DAY ON FRI. BOTH THE GFS AND
ECMWF HAVE THIS FNT ACROSS MOST OF THE PLAINS BY AFTN SO WILL HAVE
HIGHS RANGING FM THE MID TO UPPER 20S NR THE CO-WY BORDER WITH
LOWER TO MID 40S ACROSS SRN LINCOLN COUNTY.
AS FAR AS SNOW RIGHT NOW IF THE CURRENT TIMING OF THE TROUGH IS
CORRECT THERE WILL BE A PERIOD OF DECENT QG ASCENT FRI AFTN INTO
FRI NIGHT WITH FAVORABLE LAPSE RATES. THUS SHOULD SEE SNOW IN THE
MTNS THRU THE DAY ON FRI INTO FRI NIGHT. OVER NERN CO WITH UPSLOPE
COMPONENT IN PLACE BEST CHC OF SNOW LOOKS TO BE FRI AFTN INTO FRI
FRI EVENING WITH ACCUMULATIONS CERTAINLY POSSIBLE.
BY SAT THE UPPER LEVEL TROUGH MOVES ENE OF THE AREA LEAVING NW
FLOW ALOFT OVER THE AREA. ENOUGH MOISTURE WILL LINGER IN THE MTNS
FOR A CHC OF LIGHT SNOW ALTHOUGH OROGRAPHIC COMPONENT IS VERY
WEAK. OVER NERN CO WEAK UPSLOPE COMPONENT IS SHOWN ALONG THE FRONT
RANGE THRU THE DAY WITH LINGERING LOW LEVEL MOISTURE AND DECENT
LAPSE RATES. THUS COULD SEE A CHC OF LIGHT SNOW MAINLY IN AND NR
THE FOOTHILLS THRU THE AFTN HOURS. TEMPS WILL BE MUCH COLDER ON
SAT AND IT WOULD NOT SURPRISE ME IF HIGHS DID NOT GET OUT OF THE
TEENS ACROSS NERN CO.
FOR SUN NNW FLOW ALOFT WILL REMAIN OVER THE AREA WITH STILL A CHC
OF LIGHT SNOW IN THE MTNS. OVER NERN CO IT SHOULD BE DRY WITH
TEMPS REMAINING WELL BLO NORMAL AS READINGS MAY STILL HAVE A HARD
TIME GETTING ABV 20 DEGREES ESPECIALLY IF THERE IS SNOW COVER. BY
MON THE FLOW ALOFT WILL BECOME MORE NWLY. ENOUGH MOISTURE MAY
STILL LINGER IN THE MTNS FOR A SLIGHT CHC OF LIGHT SNOW. OVER NERN
CO IT WILL BE DRY WITH TEMPS REMAINING WELL BLO NORMAL AS 850-700
MB TEMPS CHANGE VERY LITTLE.
AVIATION...MID AND UPPER LEVEL CLOUDS PASSING OVER THE DENVER
METRO AREA AT THIS EARLY HOUR MARK THE PASSAGE OF A WEAK UPPER
LEVEL LOW PRESSURE TROUGH. DO NOT EXPECT TO SEE CLOUD BASES
LOWERING MUCH BELOW 10 THOUSAND FT AGL NOW THROUGH 16Z THIS
MORNING. AFTER THAT...SHOULD SEE SKIES GRADUALLY CLEARING AS
CLOUD BASES RISE WITH DRIER NORTHWESTERLY FLOW ALOFT SPREADING
OVER THE AREA. WINDS NEAR THE FOOTHILLS SUCH AS AT BJC WILL BE
WEST-SOUTHWEST AT 10-15KT FOR MUCH OF THE DAY...WITH POSSIBLE
GUSTS TO AROUND 25 KTS NOW THROUGH 15Z. OTHERWISE SOUTH-
SOUTHWEST WINDS OF 8-13KTS WILL PREVAIL AT DIA AND APA TODAY...
ALTHOUGH MAY SEE A SHORT PERIOD OF WESTERLY WINDS OF 13-18 KTS
EARLY THIS MORNING WITH PASSAGE OF THE UPPER LEVEL TROUGH AXIS.
FOR TONIGHT UNDER CLEAR/MOSTLY CLEAR SKIES...DENVER AREA AIRPORTS
SHOULD SEE THE TYPICAL DRAINAGE WIND PATTERN SET UP WITH SUNSET
WITH SPEEDS GENERALLY UNDER 12KTS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RPK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
344 PM CST TUE JAN 8 2013
.SHORT TERM...
ISSUED AT 335 PM CST TUE JAN 8 2013
(TONIGHT)
A NRN STREAM SHORTWAVE WILL PASS NORTH OF THE AREA TONIGHT ALTHOUGH
IT WILL DRAG A WEAK CDFNT THROUGH THE CWA. ATTM NO PCPN IS EXPECTED
WITH THE CDFNT DUE TO THE INITIALLY DRY AIR MASS PER 12Z SGF
SOUNDING...LIMITED MOISTURE ACCOMPANYING THE NRN STREAM
SHORTWAVE...AND UNFAVORABLE DYNAMICS THIS FAR SOUTH OF THE VORT MAX.
THE PRIMARY EFFECT OF THE CDFNT WILL BE TO CAUSE WINDS TO VEER FM
SLY TO WLY OVERNIGHT. ALTHOUGH THE NAM/SREF SEEM TO BE OVERDOING THE
LOW LEVEL MOISTURE BASED ON THE LATEST OBS...MID-LEVEL MOISTURE
SHOULD BEGIN MOVING NWD TONIGHT IN RESPONSE TO A STRONG LOW PRESSURE
SYSTEM IN NRN MEXICO/SRN TX. SOME PCPN HAS ALREADY DVLPD OVER AR
AHEAD OF THE SRN SYSTEM AND IT IS POSSIBLE THAT THERE MAY BE ENOUGH
LIFT TO SUPPORT A FEW SPRINKLES ACROSS THE SRN CWA.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 335 PM CST TUE JAN 8 2013
(WEDNESDAY THROUGH TUESDAY)
A GOOD POTENTIAL FOR SIGNIFICANT QPF IS EXPECTED FOR WED NGT THROUGH
THU NGT AS THE UPPER LEVEL LOW OVER OLD MEXICO MOVES SLOWLY NEWD
THROUGH THE SRN PLAINS WED AND WED NGT...THEN EVENTUALLY MOVES
NEWD THROUGH MO THU NGT. PREFER THE MORE NRN SOLUTION OF THE 500
MB LOW TRACK OF THE NAM AND ECMWF MODELS OVER THE GFS. MOST OF THE
PRECIPITATION SHOULD REMAIN S OF OUR FORECAST AREA ON WED...BUT
THEN SPREAD NEWD INTO MUCH OF THE REGION WED NGT AS A STRONG SLY
LOW LEVEL JET BRINGS LOW LEVEL MOISTURE NWD INTO MUCH OF MO AND
SRN IL. SHOWERS AND AT LEAST A FEW THUNDERSTORMS CAN BE EXPECTED
ON THU AS A WEAK SFC LOW AND WARM FRONT LIFT NWD INTO SRN
MO...WITH INCREASING UPPER LEVEL DIVERGENCE OVER OUR AREA AHEAD OF
THE APPROACHING UPPER LEVEL TROUGH. MUCH OF THE PRECIPITATION
SHOULD SHIFT E OF OUR AREA BY LATE THU NGT AS THE UPPER LEVEL LOW
OPENS UP AND WEAKENS AS IT MOVES TOWARDS THE GREAT LAKES REGION.
UNSEASONABLY WARM WEATHER WILL CONTINUE ON FRI WITH S-SWLY LOW
LEVEL WINDS ALONG WITH A CLEARING SKY. BOTH THE NAM AND ECMWF
MODELS FORECAST 850 MB TEMPERATURES OF AROUND 12 DEGREES C BY 00Z
SAT ACROSS MUCH OF OUR AREA. WILL LIKELY HAVE HIGHS IN THE LOWER
60S ACROSS MOST OF THE AREA ON FRI. SAT WILL BE THE LAST DAY OF
ABOVE NORMAL TEMPERATURES AS A COLD FRONT DROPS SOUTHEASTWARD
THROUGH OUR FORECAST AREA LATE FRI NGT AND SAT. ALTHOUGH THE FRONT
SHOULD MOVE THROUGH DRY THE MODELS DO GENERATE POST FRONTAL
PRECIPITATION SAT NGT AS A WEAK SFC WAVE MOVES ALONG THE FRONT
WITH AN APPROACHING POSITIVELY TILTED UPPER LEVEL TROUGH WELL WEST
OF THE AREA. LOOKS LIKE MOST OF THE PRECIPITATION WILL BE ACROSS
SERN MO AND SWRN IL IN THE WARMER AIR...BUT COULD NOT RULE OUT A
LITTLE LIGHT SNOW N AND W OF STL IN THE COLDER AIR. THE POTENTIAL
FOR AT LEAST LIGHT PRECIPITATION MAY CONTINUE ACROSS SERN MO AND
SWRN IL UNTIL MON WHEN A STRONG SFC RIDGE OVER THE NRN PLAINS
FINALLY BUILDS SEWD INTO MO WITH THE COLD FRONT SHIFTING WELL SE
OF OUR AREA. MUCH COLDER...MORE SEASONAL TEMPERATURES CAN BE
EXPECTED SUN THROUGH TUE.
GKS
&&
.AVIATION...
ISSUED AT 1124 AM CST TUE JAN 8 2013
VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY
WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY
AFTER FROPA. GENERALLY FOLLOWED THE RAP/ECMWF FOR CIG TRENDS
SINCE NAM/SREF APPEAR TO BE TOO MOIST AT LOW LEVELS. IF SFC WINDS
DECOUPLE TONIGHT THEN LLWS MAY BECOME A CONCERN BETWEEN 03-09Z
BASED ON RAP FCSTS OF WINDS ALOFT.
SPECIFICS FOR KSTL...VFR THROUGH THE PD WITH MID AND HIGH LEVEL
CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD
FRONT THEN BECOME WLY AFTER FROPA.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1138 AM CST TUE JAN 8 2013
.SHORT TERM...
ISSUED AT 356 AM CST TUE JAN 8 2013
(TODAY)
SOUTHERLY FLOW TO PERSIST ACROSS THE REGION TODAY AHEAD OF A WEAK
COLD FRONT. IN THE MEANTIME...HIGH THIN CLOUDS TO SLIDE NORTHEAST
ACROSS AREA...BUT DESPITE THE CLOUDS...WILL SEE TEMPS WARM UP INTO
THE UPPER 40S TO MID 50S WITH THE WARMEST TEMPERATURES OVER CENTRAL
MO.
BYRD
&&
.LONG TERM...
ISSUED AT 356 AM CST TUE JAN 8 2013
(TUESDAY NIGHT - WEDNESDAY)
THE WARMTH WILL PERSIST THRU THE PERIOD AS COLD AIR REMAINS LOCKED
NORTH OF THE POLAR JET STREAM ALONG THE CANADIAN BORDER. SPLIT FLOW
STHRN STREAM CUT OFF LOW CONTINUES E ACROSS NTHRN MEXICO. DECENT
SHORT WAVE WILL PASS NORTH OF THE AREA TUESDAY NIGHT. THIS WILL
ALLOW A WEAK COLD FRONT TO DROP INTO THE CWA OVERNIGHT. THE BNDRY
DOESN`T HAVE MUCH PUSH TO IT SO IT STALLS AND WASHES OUT WEDNESDAY
MORNING. THE ATMOSPHERE IS FAIRLY DRY SO THE SHORT WAVE AND ASSOC
FRONT SHOULDN/T PRODUCE MUCH MORE THAN ENHANCED MID/HIGH LEVEL
CLOUDINESS. HIGH PRESSURE QUICKLY MOVES EAST ON WEDNESDAY. WINDS
BECOME EASTERLY IN THE WAKE OF THE HIGH AND IN ADVANCE OF THE STORM
SYSTEM DUE IN FOR WEDNESDAY NIGHT. THE CUT-OFF LOW MAKES A NE TURN
AND CROSSES THE RIO GRNADE INTO TX LATE IN THE PERIOD.
MOS WAS IN DECENT AGREEMENT FOR TUESDAY NIGHT SO WENT WITH A BLEND.
WENT ABOVE THE WARMER MAV ACROSS THE NTRHN CWA WEDNESDAY. FOR THE
SOUTH...USED A BLEND AS THE GUIDANCE WAS NOT IN VERY GOOD AGREEMENT.
SOME PLACES THE MAV WAS WARMER...LIKE KFAM...WHILE OTHERS IT WAS THE
MET...KSAR AND KSLO. THIS IS DUE TO THE NAMS FASTER SOLUTION AND
QUICKER ONSET OF PRECIP ACROSS THE SOUTH.
(WEDNESDAY NIGHT - THURSDAY NIGHT)
UPPER LOW MOVES FROM TX WEDNESDAY NIGHT AND TRANSITIONS TO AN OPEN
WAVE ACROSS THE GRT LKS BY FRIDAY MORNING. THE MODELS HAVE COME INTO
BETTER AGREEMENT IN THE PAST 24 HRS AS TO LOCATION. THE NAM SOLUTION
WRT THE 500MB LOW MOVING FURTHER EAST. THIS GROUP OF
SOLUTIONS...NAM/SREF/LOCAL WRF...ARE CONSIDERABLY FASTER THAN THE
ECMWF/GEM WHILE GFS BASICALLY SPLITS THE DIFFERENCE. THIS FEATURE IS
AGAIN LIKELY NOT BEING SAMPLED WELL DUE TO HOW FAR INTO MEXICO IT
HAS PROGRESSED. THE ENERGY COMING INTO THE NW COAST OBVIOUSLY ISN/T
BEING SAMPLED WELL EITHER. UNTIL THEY ARE...THESE DIFFERENCES ARE
LIKELY NOT TO BE RESOLVED. DO NOT HAVE A STRONG OPINION ON EITHER
SCENARIO...BUT IF HAD TO MAKE A CHOICE...WOULD GO WITH THE GFS AS A
GOOD COMPROMISE. THE ECMWF SEEMS TOO SLOW OF AN OUTLIER ATM. THAT
BEING SAID...I INHERITED A FASTER ONSET TO PRECIP THAN LAST NIGHT.
CERTAINLY CAN/T RULE OUT THAT SCENARIO...SO DIDN/T CHANGE MUCH WITH
REGARDS TO TIMING. I DID BUMP POPS UP FOR THE MIDNIGHT TO NOON
THURSDAY TIME FRAME. DUE TO HOW FAR SOUTH THIS SYSTEM IS FCST TO
DIG...IT IS EXPECTED TO PULL A REMARKABLE AMOUNT OF MOISTURE NORTH
WITH IT. 850 MB DPS OF NEAR 10C AS FAR NORTH AS KSTL. THIS EQUATES
TO PWATS OF 1-1.5 INCHES...WHICH IS 2+ SD ABOVE CLIMO. THUNDER STILL
LOOKS POSSIBLE WITH THE AREAS ALONG AND S OF I44 IN MO AND I70 IN IL
WITH THE BEST CHANCES. THESE SAME AREAS MAY SEE 1-2 INCHES OF
PRECIP. DEPENDING ON THE EXACT TRACK OF THE LOW AND THE EVOLUTION OF
THE DRY SLOT...A PORTION OF THE CNTRL CWA MAY SEE SOME SUN...MIX AND
REALLY WARM UP. TRIED TO CONVEY THIS WITH LOWER 60S SOUTH OF I70.
PRECIP SHOULD COME TO AN END THURSDAY EVENING. THE WARM CONVEYOR
AHEAD OF THE FRONT SHOULD PUSH EAST WHILE PRECIP TIED TO THE UPPER
LOW LIFTS NE.
(FRIDAY - MONDAY)
THE REGION REMAINS IN SPLIT FOR FOR ONE MORE DAY. AS THE LOW PULLS
AWAY...THE CWA IS LEFT IN SW FLOW AT THE SFC AND ALOFT. FCST 850
TEMPS ARE FAIRLY REMARKABLE AT +10 TO +14 FRIDAY AFTN. IF WE ONLY
MIX TO 925MB...CLIMO INDICATES HIGH OF AT LEAST 60-65. THE GFS HINTS
THAT NW PORTIONS OF THE CWA MAY MIX TO GREATER THAN 900 MB. IF THIS
OCCURS...THEN MAX TEMPS MAY REACH 65-70. NOT READY TO JUMP ON THAT
YET...BUT IS CERTAINLY SOMETHING TO WATCH IN THE COMING DAYS AS
THOSE TEMPS COME CLOSE IF NOT EXCEED EXISTING RECORDS FOR THE DATE.
THE ENERGY THAT PUSHED THE CLOSED LOW INTO OUR AREA IS FCST TO
EFFECTIVELY PHASE THE JET STREAMS. THIS WILL ALLOW A STRONG COLD
FRONT INTO THE REGION OVER THE WKND. THE ARCTIC FRONT IS STILL ON
TRACK TO PLOW THRU THE AREA SATURDAY. THE FRONT STALLS JUST TO OUR
SE AS A WAVE OF LOW PRESSURE SLIDES NE ALONG THE FRONT SATURDAY AFTN
AND SATURDAY NIGHT. PRECIP SHOULD OVERSPREAD THE SERN HALF OF THE
CWA SATURDAY AFTN...CONTINUE SATURDAY NIGHT AND THEN END BY SUNDAY
MORNING. ATTM IT APPEARS THAT THE MAJORITY OF THE PRECIP WILL BE
LIQUID...BUT CAN/T RULE OUT WNTRY PRECIP ON THE WRN FRINGE OF THE
PRECIP SHIELD.
THE BNDRY DOESN/T SEEM TO MOVE MUCH THRU THE BEGINNING OF THE WEEK.
THE GFS AND ECMWF HAVE RIPPLES OF LOW PRESSURE THAT CONTINUE TO MOVE
ALONG THE FRONT PRODUCING WAVES OF PRECIP. TIMING AND PLACEMENT OF
THESE PRECIP EVENTS VARY...BUT THE PATTERN BEARS WATCHING.
THE ARCTIC FRONT CERTAINLY APPEARS TO HAVE INITIATED A PATTERN SHIFT
AS THE MEAN LONG WAVE TROUGH SLOWLY WORKS ACROSS THE CONUS THRU THE
WEEK KEEPING THINGS SEASONABLY COOL. THE ECMWF HINTS AT SPLIT FLOW
AGAIN FOR NEXT WEEK WITH A CUT OFF LOW OFF THE CA COAST BY MONDAY.
THANKFULLY THERE ARE SEVERAL DAYS TO WATCH THE WKND WX AND BEYOND.
MILLER
&&
.AVIATION...
ISSUED AT 1124 AM CST TUE JAN 8 2013
VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY
WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY
AFTER FROPA. GENERALLY FOLLOWED THE RAP/ECMWF FOR CIG TRENDS
SINCE NAM/SREF APPEAR TO BE TOO MOIST AT LOW LEVELS. IF SFC WINDS
DECOUPLE TONIGHT THEN LLWS MAY BECOME A CONCERN BETWEEN 03-09Z
BASED ON RAP FCSTS OF WINDS ALOFT.
SPECIFICS FOR KSTL...VFR THROUGH THE PD WITH MID AND HIGH LEVEL
CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD
FRONT THEN BECOME WLY AFTER FROPA.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1129 AM CST TUE JAN 8 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
In the short term, concerns are focused on temperatures along with
rainfall potential Wednesday night into Thursday. Early this morning,
a large upper level low continued to spin over northern Mexico as a
progressive upper trough crosses the Northern Plains. Due to an
enhanced area of cirrus moving across the region, temperatures have
remained in the 30s in most locations.
Today: Upper troughing in the Northern Plains will establish weak
surface troughing across portions of east central Kansas through
northwestern Missouri. Winds ahead of this surface trough will again
become breezy by afternoon, with abnormally warm 950:850 temperatures
supporting temperatures into the 50s in many areas. Again, have
followed short term RAP guidance for temperatures this afternoon
which did an excellent job on Monday. The warmest temperatures may
pool just ahead of this surface trough where readings could spike
into the middle 50s.
Tonight: The weak surface trough will move into the region washing
out as it does so. A bit less cirrus may be possible given the
northwesterly upper level flow. The resultant temperatures will fall
into the upper 20s in most locations.
Wednesday: The upper level low over northern Mexico will finally
become dislodged as troughing enters the Pacific Northwest. Locally,
an elongated west to east ridge of high pressure will remain over the
area throughout the daytime hours, keeping winds light and variable.
Temperatures, given the weak boundary and low level flow, will not be
quite as warm as on Tuesday but should still climb near 50.
Wednesday night: The upper level low will quickly begin to surge
north by Wednesday evening with strong low-level moisture advection
headed into the area. Showers and even embedded thunderstorms will
overspread the area through the overnight hours. Models in reasonable
agreement (less the NAM) that rain will reach the Interstate 70
corridor by midnight and northern Missouri by daybreak.
Thursday: Tricky forecast as models indicate the deep upper low will
lift across the CWA during the daytime hours. Rain should quickly
lift northward in the morning, replaced with low cloud cover and
periods of showers/drizzle. Temperatures will be rather difficult and
highly dependent on the track of surface low pressure and surge of
warm air ahead of the surface low. Model guidance suggests a weak
surface low tracking north along with the upper low through eastern
Kansas by Thursday afternoon. NAM is the most aggressive bringing
near 60 degree readings into the CWA, but it is also the deepest and
most progressive solution of all guidance. Prefer the weaker
solutions of the GFS/SREF which still bring low 50s by the late
afternoon hours.
Dux
Medium Range (Friday through Monday)...
The medium range should start out very warm especially for the
climatologically coldest week of the year for Kansas City (January
10-17). With 850mb temps between 12C-14C, if we can mix out enough,
temperatures could easily range into the mid 50s to mid 60s.
However, those warm temperatures will be short-lived as a cold front
is forced into the forecast area Friday night in association with a
broad and deep upper level trough that will be traversing the
Rockies. This frontal passage looks to be dry as models are in good
agreement that the best moisture transport is south and east of the
forecast area. As such have lowered chance POPs inherited by the
initialization to silent slight chance POPs for Saturday. The main
effect of this cold front will be the marked change in temperatures.
High temperatures across the CWA Saturday will experience a 20
degree range from near 30 across northern Missouri where cold air
advection will be ongoing by day break...to near 50 across central
Missouri where cold air doesn`t begin to advect in until later in
the day. The upper level trough moves through the area on Sunday as
high pressure builds in at the surface with highs in the mid 20s to
lower 30s. Surface high pressure strengths over the area on Monday
and with abundant sunshine highs will return to near normal for the
coldest climatological week of the year with highs in the 30s.
73
&&
.AVIATION...
For the 18Z TAFs...VFR conditions will persist. South-southwest
winds will veer to the west this evening with the passage of a weak
surface trough. Winds will continue to veer to the north Wednesday
morning in response to the cut-off low approaching from the south.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1231 PM EST TUE JAN 8 2013
.SYNOPSIS...
A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF
HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST
OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN
CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE
UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...WELL WELL...THE COMBO OF THE HRRR/RUC
MENTIONED EARLIER AS UNLIKELY APPEARS TO HAVE BEEN THE WAY TO GO.
DESPITE THE SYNOPTIC PATTERN AND LOW LEVEL WINDS FAVORING A
CONTINUATION OF THE WEDGE-LIKE CONDITIONS SKIES HAVE AT LEAST
TEMPORARILY BECOME MOSTLY SUNNY ACROSS MOST OF OUR FORECAST AREA
WEST OF THE IMMEDIATE NORTH CAROLINA COAST AND TEMPERATURES ARE
ROCKETING THROUGH THE 50S. DENSER MID-LEVEL CLOUDS ACROSS SOUTHERN
AND CENTRAL SOUTH CAROLINA WILL MOVE INTO THE REGION IN THE NEXT
COUPLE OF HOURS WHICH SHOULD STOP THE TEMPERATURES FROM RISING...BUT
UNTIL THEN BASED ON CURRENT DATA I AM EXPANDING THE AREA EXPECTED TO
REACH 60-62 DEGREES TO COVER MOST OF OUR SOUTH CAROLINA FORECAST
AREA EAST OF I-95 AND AWAY FROM THE BEACHES. ACROSS SE NORTH
CAROLINA MOST PLACES SHOULD REACH THE UPPER 50S...EXCEPT WITHIN 5-10
MILES OF THE NEW HANOVER AND PENDER COUNTY COAST WHERE STUBBORN
CLOUDS AND THE REMNANT OF THIS MORNING`S CHILLY LOW-LEVEL AIRMASS
WILL HOLD TEMPERATURES SEVERAL DEGREES COOLER. PREVIOUS DISCUSSION
FROM 930 AM FOLLOWS...
HIGH PRESSURE ALONG THE MID-ATLANTIC COAST AND A WEAK COASTAL TROUGH
ROUGHLY 30-40 MILES OFFSHORE ARE PRODUCING A COOL NORTHEAST WIND
ACROSS THE EASTERN CAROLINAS. SATELLITE SHOWS LOW AND MID-LEVEL
CLOUD COVER ASSOCIATED WITH MOIST ATLANTIC AIR OVERRIDING THE
SHALLOW COLD AIRMASS INLAND. THERE ARE SOME SIZABLE HOLES IN THESE
CLOUD DECKS MAINLY ACROSS EASTERN SOUTH CAROLINA...AND THIS IS
COMPLICATING OUR FORECAST FOR TODAY.
CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS
RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND
HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN
FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF
OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND
LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE
CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE
COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE
CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA
EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN
MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY.
ELSEWHERE...MID 50S SHOULD PREDOMINATE.
RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF
STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND.
THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY
DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS
GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE
PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE
RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST.
MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS
MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A
SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH
MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP
THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND
SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH
WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH
THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A
BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS
THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN
RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER
AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE
SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT
AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR
THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL
LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS
INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND
HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP
HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS
WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE
GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD
AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS.
TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA
AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE
BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL
AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA.
EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR
ABOVE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS
UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY
FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE
CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM
AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE
SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE
EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF
THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID
LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE
SOME CLOUDS THROUGH THE PERIOD.
H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE
WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT
WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON
HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR
THIS TIME OF YEAR...IN THE MID 50S.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 18Z...VISIBLE SATELLITE IMAGERY SHOWS SCT/BKN LOW TO MID LEVEL
CLOUDS ACROSS THE CWA ASSOCIATED WITH A WEAK COASTAL TROUGH. THIS
CLOUD COVER IS EXPECTED TO LINGER INTO THE OVERNIGHT HOURS. MOIST
RETURN FLOW AROUND THE HIGH PRESSURE CENTERED OFFSHORE HAS INCREASED
DEWPOINTS ACROSS THE AREA. FORECAST SOUNDINGS SHOW A PRONOUNCED
LOW-LEVEL INVERSION DEVELOPING OVERNIGHT...WHICH SHOULD TRAP THIS
MOISTURE NEAR THE SURFACE AND SUPPORT FOG/STRATUS DEVELOPMENT EARLY
WEDNESDAY. BASED ON THE LATEST MODEL GUIDANCE...HAVE INCREASING
CONFIDENCE FOR MVFR CIGS/VSBYS AT ALL TERMS AFTER 06Z...BECOMING IFR
IN THE EARLY MORNING HOURS. CONDITIONS SHOULD IMPROVE TO MVFR BY
LATE WEDNESDAY MORNING. EXPECT EAST WINDS AOB 8 KNOTS TODAY WITH
LIGHT AND VARIABLE WINDS OVERNIGHT.
EXTENDED OUTLOOK...SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO
THURSDAY. POSSIBLE MVFR/IFR CIGS/VSBYS THURSDAY MORNING. VFR
DEVELOPING FRIDAY AND PERSISTING THROUGH SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...COOL NORTHEAST WINDS CONTINUE ACROSS THE
COASTAL WATERS...ALTHOUGH WITH WIND SPEEDS NOTABLY LESS THAN
OBSERVED 3-6 HOURS AGO. THIS IS INLINE WITH OUR PREVIOUS FORECAST
AND NO SIGNIFICANT CHANGES ARE NEEDED THROUGH THIS EVENING. PREVIOUS
DISCUSSION FROM 930 AM FOLLOWS...
BASED ON DATA FROM THE FRYING PAN SHOALS BUOY SHOWING A SOUTHEAST
WIND AND 66 DEGREE AIR TEMPERATURES...THE COASTAL TROUGH LIES JUST
TO THEIR WEST. ALL OTHER BUOY AND COASTAL LOCATIONS HAVE MUCH COLDER
AIR TEMPERATURES WITH NORTH TO NORTHEAST WINDS. MODEL CONSENSUS IS
THIS TROUGH SHOULD WEAKEN THIS AFTERNOON AND ESPECIALLY TONIGHT AS
THE HIGH ALONG THE MID-ATLANTIC COAST NUDGES BACK TO THE SOUTH.
RADAR SHOWS SOME PATCHY LIGHT RAIN JUST EAST OF CAPE FEAR CURRENTLY.
THIS PRECIPITATION SHOULD MOVE SLOWLY NORTH THIS MORNING POTENTIALLY
AFFECTING THE COASTAL WATERS NEAR CAROLINA BEACH BEFORE DISSIPATING
THIS AFTERNOON.
THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS
DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15
KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE
FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH
BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS
THROUGH 11 AM.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS
HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE
LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND
TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO
AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH
AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL
BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL
RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO
FRI.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE
SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH
PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL
GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO
10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON
FRI DOWN TO 2 TO 3 FT BY SAT NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1210 PM EST TUE JAN 8 2013
.SYNOPSIS...
A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF
HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST
OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN
CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE
UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...WELL WELL...THE COMBO OF THE HRRR/RUC
MENTIONED EARLIER AS UNLIKELY APPEARS TO HAVE BEEN THE WAY TO GO.
DESPITE THE SYNOPTIC PATTERN AND LOW LEVEL WINDS FAVORING A
CONTINUATION OF THE WEDGE-LIKE CONDITIONS SKIES HAVE AT LEAST
TEMPORARILY BECOME MOSTLY SUNNY ACROSS MOST OF OUR FORECAST AREA
WEST OF THE IMMEDIATE NORTH CAROLINA COAST AND TEMPERATURES ARE
ROCKETING THROUGH THE 50S. DENSER MID-LEVEL CLOUDS ACROSS SOUTHERN
AND CENTRAL SOUTH CAROLINA WILL MOVE INTO THE REGION IN THE NEXT
COUPLE OF HOURS WHICH SHOULD STOP THE TEMPERATURES FROM RISING...BUT
UNTIL THEN BASED ON CURRENT DATA I AM EXPANDING THE AREA EXPECTED TO
REACH 60-62 DEGREES TO COVER MOST OF OUR SOUTH CAROLINA FORECAST
AREA EAST OF I-95 AND AWAY FROM THE BEACHES. ACROSS SE NORTH
CAROLINA MOST PLACES SHOULD REACH THE UPPER 50S...EXCEPT WITHIN 5-10
MILES OF THE NEW HANOVER AND PENDER COUNTY COAST WHERE STUBBORN
CLOUDS AND THE REMNANT OF THIS MORNING`S CHILLY LOW-LEVEL AIRMASS
WILL HOLD TEMPERATURES SEVERAL DEGREES COOLER. PREVIOUS DISCUSSION
FROM 930 AM FOLLOWS...
HIGH PRESSURE ALONG THE MID-ATLANTIC COAST AND A WEAK COASTAL TROUGH
ROUGHLY 30-40 MILES OFFSHORE ARE PRODUCING A COOL NORTHEAST WIND
ACROSS THE EASTERN CAROLINAS. SATELLITE SHOWS LOW AND MID-LEVEL
CLOUD COVER ASSOCIATED WITH MOIST ATLANTIC AIR OVERRIDING THE
SHALLOW COLD AIRMASS INLAND. THERE ARE SOME SIZABLE HOLES IN THESE
CLOUD DECKS MAINLY ACROSS EASTERN SOUTH CAROLINA...AND THIS IS
COMPLICATING OUR FORECAST FOR TODAY.
CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS
RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND
HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN
FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF
OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND
LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE
CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE
COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE
CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA
EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN
MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY.
ELSEWHERE...MID 50S SHOULD PREDOMINATE.
RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF
STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND.
THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY
DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS
GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE
PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE
RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST.
MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS
MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A
SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH
MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP
THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND
SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH
WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH
THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A
BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS
THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN
RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER
AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE
SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT
AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR
THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL
LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS
INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND
HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP
HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS
WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE
GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD
AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS.
TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA
AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE
BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL
AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA.
EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR
ABOVE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS
UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY
FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE
CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM
AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE
SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE
EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF
THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID
LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE
SOME CLOUDS THROUGH THE PERIOD.
H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE
WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT
WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON
HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR
THIS TIME OF YEAR...IN THE MID 50S.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...VFR/MVFR CIGS ACROSS THE AREA THIS MORNING AS SATELLITE
IMAGERY DEPICTS PLENTY OF LOW-LEVEL CLOUD COVER ASSOCIATED WITH A
COASTAL TROUGH. MOIST RETURN FLOW AROUND THE HIGH PRESSURE CENTERED
OFFSHORE WILL KEEP THE LOW CLOUDS AROUND THROUGH THIS TAF PERIOD. IT
APPEARS THAT LOW VFR CIGS WILL BE MOST PREVALENT ACROSS THE AREA
TODAY...ALTHOUGH SOME MVFR CIGS ARE POSSIBLE AS WELL. COULD SEE SOME
ISOLATED DRIZZLE ALONG THE COAST...BUT DECIDED IT WAS NOT WORTH
MENTIONING IN TAFS. EXPECT EAST WINDS AOB 8 KNOTS TODAY...BECOMING
LIGHT/CALM OVERNIGHT. MODEL SOUNDINGS AND GUIDANCE BOTH SUPPORT A
FOG/STRATUS EVENT OVERNIGHT WITH ABUNDANT LOW-LEVEL MOISTURE IN
PLACE ACROSS THE REGION. INCLUDED MVFR CIGS/VSBYS AFTER MIDNIGHT AT
ALL TERMINALS...AND IFR CONDITIONS COULD DEVELOP TOWARDS THE END OF
THE TAF PERIOD.
EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS WEDNESDAY AND THURSDAY.
SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO THURSDAY. VFR
DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...COOL NORTHEAST WINDS CONTINUE ACROSS THE
COASTAL WATERS...ALTHOUGH WITH WIND SPEEDS NOTABLY LESS THAN
OBSERVED 3-6 HOURS AGO. THIS IS INLINE WITH OUR PREVIOUS FORECAST
AND NO SIGNIFICANT CHANGES ARE NEEDED THROUGH THIS EVENING. PREVIOUS
DISCUSSION FROM 930 AM FOLLOWS...
BASED ON DATA FROM THE FRYING PAN SHOALS BUOY SHOWING A SOUTHEAST
WIND AND 66 DEGREE AIR TEMPERATURES...THE COASTAL TROUGH LIES JUST
TO THEIR WEST. ALL OTHER BUOY AND COASTAL LOCATIONS HAVE MUCH COLDER
AIR TEMPERATURES WITH NORTH TO NORTHEAST WINDS. MODEL CONSENSUS IS
THIS TROUGH SHOULD WEAKEN THIS AFTERNOON AND ESPECIALLY TONIGHT AS
THE HIGH ALONG THE MID-ATLANTIC COAST NUDGES BACK TO THE SOUTH.
RADAR SHOWS SOME PATCHY LIGHT RAIN JUST EAST OF CAPE FEAR CURRENTLY.
THIS PRECIPITATION SHOULD MOVE SLOWLY NORTH THIS MORNING POTENTIALLY
AFFECTING THE COASTAL WATERS NEAR CAROLINA BEACH BEFORE DISSIPATING
THIS AFTERNOON.
THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS
DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15
KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE
FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH
BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS
THROUGH 11 AM.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS
HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE
LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND
TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO
AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH
AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL
BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL
RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO
FRI.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE
SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH
PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL
GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO
10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON
FRI DOWN TO 2 TO 3 FT BY SAT NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1036 AM CST TUE JAN 8 2013
.DISCUSSION...
MAIN CHANGE FOR THIS MORNING WAS TO ADD SOME FZDL MENTION FOR THE
REST OF THE MORNING INTO THE EARLY AFTERNOON. PRECIP HAS ENTERED
THE CWA MAINLY FROM THE RED RIVER VALLEY WESTWARD. NOT MUCH SNOW
ACCUMULATION SO FAR...BUT WE HAVE HAD A FEW REPORTS OF SLICK ROADS
DUE TO FZDL AROUND FARGO TOWARDS CASSELTON. MODEL SOUNDINGS HAVE A
SHALLOW MOIST LAYER WITH A DRY WARM LAYER ABOVE THROUGH MID
AFTERNOON. TEMPS HAVE BEEN QUICK TO WARM UP THIS MORNING OVER THE
WESTERN CWA EVEN WITH WINDS STILL FROM THE SOUTH. RAP SEEMS TO
HAVE A GOOD HANDLE ON THE WARMING AND WENT CLOSE TO THAT MODEL
SOLUTION FOR THE REST OF THE DAY. CONTINUE TO THINK THAT TEMPS
WILL WARM TO CLOSE TO THE FREEZING MARK BY THIS AFTERNOON.
MOST OF THE PRECIP SHOULD BE OVER THE NORTHEASTERN CWA BY LATE THIS
POINT...AND THAT AREA SHOULD BE A BIT COLDER SO KEPT TYPE AS SNOW
FOR NOW BUT WILL HAVE TO KEEP AN EYE ON IT.
WINDS WILL ALSO BE AN ISSUE FROM LATE THIS AFTERNOON INTO THE
EVENING. SOME OF THE MODEL GUIDANCE HAS THE NORTHWESTERN TO NORTH
CENTRAL CWA FLIRTING WITH ADVISORY CRITERIA. ON THE OTHER
HAND...MIXING WILL BE AT A MINIMUM AND THERE IS NO COLD AIR
ADVECTION TO HELP BRING HIGHER LEVEL WINDS TO THE SFC. WILL HOLD
OFF ON ANY HEADLINES FOR NOW AND REEVALUATE FOR THE AFTERNOON PACKAGE.
&&
.AVIATION...
WILL SEE INCREASING CLOUD COVER WITH PERIODS OF LIGHT SNOW
FROM WEST TO EAST TODAY AS A LOW PRESSURE SYSTEM MOVES ACROSS THE
REGION. VFR CEILINGS SHOULD DOMINATE...BUT MAY BRIEFLY DIP INTO
THE MVFR RANGE WITH LIGHT SNOW AND REDUCTIONS IN VISIBILITY DOWN
TO 1-5 SM. SOUTH-SOUTHWEST WIND WILL SHIFT TO THE WEST LATER THIS
AFTERNOON AND EVENING BEHIND COLD FRONT WITH FREQUENT GUSTS AT OR
ABOVE 30 KTS.
&&
.PREV DISCUSSION... /ISSUED 353 AM CST TUE JAN 8 2013/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
FORECAST CHALLENGES INCLUDE SNOW CHANCES/AMOUNTS AND WIND TODAY...
FOLLOWED BY PRECIPITATION CHANCES AGAIN ON THURSDAY. GFS/NAM/ECMWF/
GEM ARE IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION.
FOR TODAY...EASTERN PACIFIC SHORT-WAVE WILL MOVE ACROSS SOUTHERN
CANADA AND THE NORTHERN PLAINS. SURFACE LOW WILL REMAIN NORTH OF
THE BORDER...BUT THE COLD FRONT/TROUGH AXIS WILL MOVE ACROSS THE
ND/MN BORDER AND INTO NORTHWEST MN BY 00 UTC TONIGHT. MID-LEVEL
FRONTOGENESIS AND MOISTURE NOT ALL TOO IMPRESSIVE...BUT 300 HPA
JET STREAK...COMBINED WITH MID-LEVEL CONVERGENCE WILL RESULT IN
LIGHT SNOW MOVING ACROSS THE FORECAST AREA TODAY. WILL BE A HIGH
POP/LOW QPF SCENARIO WITH THE BEST CHANCES FOR ACCUMULATING
SNOWFALL ALONG AND NORTH OF THE HIGHWAY 2 CORRIDOR. MOST AREAS
WILL SEE AN INCH OR LESS THROUGH WEDNESDAY MORNING...BUT UP TO 2
INCHES ARE POSSIBLE ACROSS THE LAKE OF THE WOODS AREA. WITH LESS
FAVORABLE SOUTHERLY SURFACE WIND AHEAD OF THE FRONT AND MODEST
COLD AIR ADVECTION IN ITS WAKE...EXPECT HIGH TEMPERATURES TODAY
AT OR SLIGHTLY COOLER THAN YESTERDAY.
MODELS STILL SHOW 40 TO 50 KTS AT 925 HPA ALONG AND WEST OF THE
VALLEY BY 06 UTC TONIGHT. PREFER NAM/S DEPICTION OF MIXED BOUNDARY
LAYER...WHICH DEEPENS IT TO AROUND 950 HPA OVERNIGHT. THIS PROVIDES
AROUND 30 KTS TO MIX TO THE SURFACE IN AREA OF STRONGEST PRESSURE
GRADIENT. AS A RESULT...LEANED TOWARDS HIGHEST LOCAL WRF GUIDANCE
FOR WIND SPEED...BUT THIS STILL KEEPS IT JUST BELOW WIND ADVISORY
CRITERIA (SUSTAINED 30 MPH). COULD SEE A FEW HOURS GREATER THAN 30
MPH WEST OF THE VALLEY...BUT CONFIDENCE NOT HIGH ENOUGH TO ISSUE
ANY HEADLINES AT THIS TIME. WILL ALLOW DAY SHIFT TO RE-EVALUATE
SINCE THE STRONGEST WIND WOULD BE DELAYED UNTIL AFTER 21 UTC THIS
AFTERNOON. ALTHOUGH MAJORITY OF FALLING SNOW WILL END AFTER 00
UTC...DID INCLUDE AREAS OF BLOWING SNOW THIS EVENING INTO THE
EARLY MORNING HOURS WEDNESDAY ALONG AND WEST OF THE VALLEY.
REMAINING SNOW WILL MOVE OUT OF THE REGION BY WEDNESDAY MORNING
WITH A SURFACE RIDGE MOVING ACROSS THE FORECAST AREA. EXPECT
PLENTY OF SUNSHINE WEDNESDAY...BUT TEMPERATURES WILL BE A BIT
COOLER WITH AFTERNOON HIGHS IN THE MID 20S ALONG THE CANADIAN
BORDER TO NEAR 30 DEGREES ACROSS THE SOUTHERN VALLEY. WINDS WILL
BE LIGHT FROM THE WEST-SOUTHWEST.
MOST OF THURSDAY WILL BE DRY...BUT MODELS DO HINT THAT THE
NORTHWEST FLANK OF A PRECIPITATION SHIELD ASSOCIATED WITH A GREAT
LAKES LOW PRESSURE SYSTEM WILL CLIP PORTIONS OF THE SOUTHEAST
FORECAST AREA THURSDAY EVENING. WILL KEEP 40 TO 60 POPS FOR THIS
PERIOD ALONG AND EAST OF THE VALLEY. BIGGER STORY FOR THURSDAY
WILL BE WARM TEMPERATURES WITH 850 HPA VALUES CLIMBING TO +6 C.
THIS SHOULD TRANSLATE TO SURFACE TEMPERATURES IN THE MID 30S. IF
PRECIPITATION DOES TRACK FARTHER NORTH...MAY NEED TO WATCH
P-TYPE GIVEN WARM MID-LEVELS.
LONG TERM...FRIDAY THROUGH MONDAY NIGHT
MODELS ARE COMING INTO BETTER AGREEMENT WITH AN ACTIVE WEATHER
PATTERN FOR FRI-SAT...WITH SW FLOW ALOFT. THERE ARE DIFFERENCES IN
THE DETAILS AND EXACT TIMING...BUT ALL INDICATIONS POINTING TO
ACCUMULATING SNOW POSSIBLE FRIDAY INTO SATURDAY...MUCH COLDER TEMPS
AND NORTHERLY WINDS INCREASING. FOR NOW HAVE KEPT WITH CHANCE POPS
FOR LIGHT SNOW FRI INTO SAT...BUT WE MAY NEED TO INCREASE THESE POPS
WITH SEVERAL SHORTWAVES MOVING THROUGH. THE BEST CHANCE FOR
ACCUMULATING SNOW AND POTENTIAL WINTER WEATHER HEADLINES WOULD BE
FRI AFTERNOON INTO SATURDAY...ALTHOUGH TIMING OF THIS MAY CHANGE
WITH PLENTY OF TIME TO RESOLVE MODEL DIFFERENCES.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1158 AM CST TUE JAN 8 2013
.AVIATION...
/18Z TAFS/
CONCERNS...ONGOING LOW CIGS/VSBY AND THUNDER POTENTIAL.
INITIAL MASS OF LIGHT RAIN ASSOCIATED WITH LARGE UPPER LEVEL STORM
SYSTEM OVER NORTHERN MEXICO HAS MOVED INTO N TEXAS THIS
MORNING...BRINGING WIDESPREAD MVFR/AREAS OF IFR TO ALL SITES. AS
MOISTURE INFLOW AND LIFT INCREASE AHEAD OF THIS SYSTEM LATER
TODAY/TONIGHT...EXPECT WIDESPREAD RAIN AND IFR CONDITIONS TO
DEVELOP AND PERSIST THROUGH AT LEAST MIDDAY WED. LIMITED
INSTABILITY EXISTS ALOFT...INCREASING TO THE S AND E OF THE
METROPLEX TAF SITES. GIVEN THIS...EXPECT OCCASIONAL THUNDER AT ALL
TAF SITES THROUGH TONIGHT. SURFACE WINDS SHOULD CONTINUE TO BACK
TO A NE-N DIRECTION TONIGHT AND INCREASE AS SURFACE LOW DEVELOPS
OVER S TEXAS.
66
&&
.UPDATE...
CURRENT FORECAST IS IN GOOD SHAPE AND ONLY MADE SOME MINOR CHANGES
TO THE SKY/POP GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONS. CURRENT
ANALYSIS OF AVAILABLE 12Z GUIDANCE CONTINUES TO SHOW THAT
WIDESPREAD HEAVY RAINFALL IS LIKELY THROUGH WEDNESDAY. INITIAL
ACTIVITY HAS BEEN SOMEWHAT SCATTERED AS BROAD ISENTROPIC ASCENT
OVERSPREADS THE AREA. LATEST RAP SOUNDINGS FROM ACROSS NORTH TEXAS
INDICATE ABOUT 100-200J/KG OF ELEVATED INSTABILITY WHICH HAS BEEN
SUFFICIENT FOR ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING SMALL
HAIL. AS DEEPER LARGE SCALE FORCING OVERSPREADS CENTRAL AND NORTH
TEXAS TONIGHT...A WELL DEFINED WARM CONVEYOR BELT WILL BECOME
ESTABLISHED AND AREAL COVERAGE OF PRECIPITATION IS EXPECTED TO
INCREASE. HEAVIEST RAINS STILL EXPECTED OVERNIGHT TONIGHT INTO
EARLY WEDNESDAY...SO NO CHANGES NEEDED ATTM TO THE FLASH FLOOD
WATCH. THE THREAT FOR SEVERE WEATHER STILL APPEARS FAIRLY LOW AND
SHOULD BE CONFINED TO THE SOUTHEAST COUNTIES LATE TONIGHT INTO
WEDNESDAY.
DUNN
&&
.PREV DISCUSSION... /ISSUED 427 AM CST TUE JAN 8 2013/
MODEL GUIDANCE IS IN GOOD AGREEMENT AND NOW OFFERS A REASONABLE
TRACK FEATURING MORE OF A SMOOTH PENDULUM SWING OF THE UPPER LOW
THROUGH NORTHERN MEXICO TONIGHT BEFORE EJECTING NORTHEAST AND OVER
NORTH CENTRAL TEXAS WEDNESDAY EVENING. THE MODELS HAVE BACKED OFF
THE SLOWER/WOBBLY TRACK THAT TOOK THE LOW WELL WEST OF THE CWA.
THIS MEANS THE SYSTEM WILL BE IN AND OUT MORE QUICKLY...AND
TIMING FOR THE HEAVIEST RAINFALL AND MOST ROBUST CONVECTION NOW
LOOKS LIKE TONIGHT AND WEDNESDAY MORNING. THIS ALSO MEANS THE WARM
SECTOR WILL HAVE LESS TIME TO PENETRATE THE CWA WITH THE SEVERE
THREAT RELEGATED TO THE FAR SE ZONES BETWEEN 3 AM AND 9 AM WED.
ISENTROPIC LIFT HAS BEGUN ACROSS NORTH TEXAS AND CLOUDS WILL
CONTINUE TO THICKEN AND LOWER THROUGH THE DAY. SHOWERS AND AREAS
OF DRIZZLE HAVE ALREADY DEVELOPED ACROSS CENTRAL TEXAS. MODEL
SOUNDINGS REVEAL MUCAPE VALUES OF 100 J/KG NORTH TO 500 J/KG SOUTH
FOR PARCELS NEAR 800MB. THIS MEANS A FEW THUNDERSTORMS WILL
DEVELOP ONCE THE ISENTROPIC LIFT BEGINS ON THE 325K SURFACE
WHICH SHOULD OCCUR AFTER 9AM. SHOWERS/STORMS WILL BECOME NUMEROUS
DURING THE DAY AND SPREAD N/NE. IN THE MEANTIME A DEVELOPING
INVERTED SURFACE TROUGH AND LOW CENTER IN SOUTH TEXAS WILL CAUSE
WINDS TO BACK TO THE NORTHEAST. COLD ADVECTION...CLOUDS AND RAIN
WILL KEEP HIGHS IN THE UPPER 40S WEST TO LOW 50S EAST.
ISENTROPIC LIFT INTENSIFIES SUBSTANTIALLY TONIGHT AS LOW LEVEL
WIND FIELDS INCREASE AND BACK TO THE SOUTHEAST. MOISTURE FLUX AND
THETA-E ADVECTION VALUES ARE VERY HIGH. CONSIDERING THE WARM
CONVEYOR BELT WILL BE TAPPING INTO UNSEASONABLY HIGH PRECIPITABLE
WATER VALUES OF ALMOST 2 INCHES IN THE GULF...THIS WILL ALLOW A
WIDESPREAD AREA OF RAIN TO DEVELOP TONIGHT AND PERSIST INTO
WEDNESDAY MORNING ACROSS NORTH TEXAS IN THE COLD SECTOR. WHILE
RAINFALL RATES WILL LIKELY NOT EXCEED AN INCH PER HOUR...THE
CONTINUOUS RAINS SHOULD HELP GENERATE EXCESSIVE RUNOFF. HEAVY RAIN
EVENTS IN THE COLD SEASON TEND TO PRODUCE MORE RUNOFF THAN IN THE
WARM SEASON. MOST VEGETATION IS DORMANT AND THEREFORE IT DOES NOT
TAKE MUCH OF THE RAIN WATER OUT OF THE SOILS. WE ARE OUTLOOKED IN
SLIGHT RISK FOR EXCESSIVE RAINFALL BY HPC AND HAVE ISSUED A FLASH
FLOOD WATCH FOR AREAS WHERE WE EXPECT 2 TO 4 INCHES OF RAIN. THE
METROPLEX IS ON THE EDGE OR JUST NORTHWEST OF THE HEAVY RAIN AXIS
BUT WE BROUGHT THE WATCH INTO TARRANT/DALLAS/COLLIN COUNTIES
BECAUSE THE URBANIZATION IS MORE SENSITIVE TO HEAVY RAINFALL.
CONCERNING THE SEVERE WEATHER THREAT...A LINE OF STORMS SHOULD
FORM IN SOUTH CENTRAL TEXAS THIS EVENING AND MOVE RATHER SLOWLY
TO THE E/NE INTO OUR FAR SOUTH/SOUTHEAST ZONES AFTER 3 AM.
ALTHOUGH THE WARM SECTOR DOES MAKE IT INTO THE SOUTHEAST ZONES
AHEAD OF THE LINE...IT IS AT THE COOLEST TIME OF THE DAY. THIS
WILL LIKELY LIMIT SURFACE BASED CAPE TO LESS THAN 100 J/KG IF
ANYTHING AT ALL. BECAUSE SHEAR WILL BE HIGH...WE WILL HAVE TO
MONITOR THIS CLOSELY...BUT AT THIS TIME THE SEVERE WEATHER THREAT
LOOKS MORE CONDITIONAL THAN PREVIOUS FORECASTS WHICH HAD THE LINE
MOVING IN DURING THE WARMER AFTERNOON HOURS.
PASSAGE OF THE SURFACE TROUGH WILL BE SUCCEEDED BY DRY SLOT ALOFT
WHICH SHOULD END MOST OF THE RAIN FROM WEST TO EAST DURING THE DAY
WEDNESDAY. A FEW ELEVATED SHOWERS WILL REMAIN POSSIBLE WEDNESDAY
EVENING BUT HAVE LOWERED POPS DUE TO THE FASTER TIMING. SOME WRAP
AROUND CLOUDS WILL AFFECT THE NW ZONES THURSDAY...BUT OTHERWISE
GENERALLY FAIR WEATHER WITH WARMER TEMPS DUE TO SW WINDS. FRIDAY
WILL BE SUNNY AND WARMER WITH HIGHS NEAR 70. THE NEXT FRONT WILL
ARRIVE SATURDAY AND BRING A SLIGHT CHANCE OF CONVECTION OVER THE
EASTERN HALF OF THE AREA. TEMPS WILL COOL INTO THE 30S FOR LOWS
SAT NIGHT...WITH THE UPPER LEVEL PATTERN FAVORABLE FOR SEVERAL
DAYS OF COLD ADVECTION INTO NEXT WEEK. HIGH TEMPS WILL BE CHILLY
SUNDAY INTO MID WEEK...GENERALLY IN THE LOW-MID 40S. GFS HAS
BACKED OFF ON PRECIPITATION SUNDAY WHICH IS WHAT THE OTHER MODELS
WERE FORECASTING...HOWEVER THERE IS A LITTLE MORE EVIDENCE THAT WE
WILL CONTEND WITH POSSIBLE WINTRY PRECIPITATION FOR THE MIDDLE OF
NEXT WEEK WHEN THE UPPER LEVEL PATTERN BECOMES MORE FAVORABLE.
TR.92
&&
.CLIMATE...
IN THE DALLAS/FORT WORTH METROPLEX...24-HOUR RAINFALL (MIDDAY
TODAY TO MIDDAY WEDNESDAY) MAY REACH 3 INCHES. WHEN WAS THE LAST
TIME DFW AIRPORT SAW THAT MUCH PRECIPITATION IN A 24 HOUR PERIOD?
APRIL 8, 2012 (EASTER SUNDAY) - 2.23
MARCH 19-20, 2012 - 4.04
JANUARY 24-25, 2012 - 4.27
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 51 47 56 46 60 / 100 100 100 50 10
WACO, TX 52 49 57 45 64 / 100 100 100 30 10
PARIS, TX 52 47 57 51 60 / 90 100 100 80 10
DENTON, TX 50 45 54 45 59 / 100 100 90 60 10
MCKINNEY, TX 51 47 56 47 59 / 100 100 100 60 10
DALLAS, TX 51 47 56 46 60 / 100 100 100 50 10
TERRELL, TX 52 49 57 50 61 / 100 100 100 60 10
CORSICANA, TX 53 51 58 49 63 / 100 100 100 40 10
TEMPLE, TX 53 49 58 45 65 / 100 100 100 30 10
MINERAL WELLS, TX 48 44 54 42 60 / 90 100 80 50 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH WEDNESDAY
AFTERNOON FOR TXZ094-095-104>107-118>123-133>135-145>148-158>162-
174-175.
&&
$$
/
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1108 AM CST TUE JAN 8 2013
.UPDATE...
CURRENT FORECAST IS IN GOOD SHAPE AND ONLY MADE SOME MINOR CHANGES
TO THE SKY/POP GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONS. CURRENT
ANALYSIS OF AVAILABLE 12Z GUIDANCE CONTINUES TO SHOW THAT
WIDESPREAD HEAVY RAINFALL IS LIKELY THROUGH WEDNESDAY. INITIAL
ACTIVITY HAS BEEN SOMEWHAT SCATTERED AS BROAD ISENTROPIC ASCENT
OVERSPREADS THE AREA. LATEST RAP SOUNDINGS FROM ACROSS NORTH TEXAS
INDICATE ABOUT 100-200J/KG OF ELEVATED INSTABILITY WHICH HAS BEEN
SUFFICIENT FOR ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING SMALL
HAIL. AS DEEPER LARGE SCALE FORCING OVERSPREADS CENTRAL AND NORTH
TEXAS TONIGHT...A WELL DEFINED WARM CONVEYOR BELT WILL BECOME
ESTABLISHED AND AREAL COVERAGE OF PRECIPITATION IS EXPECTED TO
INCREASE. HEAVIEST RAINS STILL EXPECTED OVERNIGHT TONIGHT INTO
EARLY WEDNESDAY...SO NO CHANGES NEEDED ATTM TO THE FLASH FLOOD
WATCH. THE THREAT FOR SEVERE WEATHER STILL APPEARS FAIRLY LOW AND
SHOULD BE CONFINED TO THE SOUTHEAST COUNTIES LATE TONIGHT INTO
WEDNESDAY.
DUNN
&&
.AVIATION...
/12Z TAFS/
CONCERNS...RAIN WITH DETERIORATING CIGS/VSBY...THUNDER POTENTIAL.
CIGS/VSBY...
AT 12Z TAF ISSUANCE TIME...SCATTERED SHOWERS HAVE ALREADY REACHED
AREAS NORTH OF THE I-20 CORRIDOR. AS UPGLIDE INTENSIFIES FURTHER
THIS MORNING...THE ACTIVITY WILL INCREASE IN INTENSITY AND AREAL
COVERAGE. THE RESULTING TOP-DOWN SATURATION WILL RAPIDLY LOWER
CEILINGS...WHICH SHOULD FALL INTO THE IFR CATEGORY BY EARLY
AFTERNOON. VISIBILITY WILL DETERIORATE IN TANDEM BUT WILL REMAIN
VARIABLE WITH INTERMITTENT PRECIPITATION. IFR CONDITIONS WILL
PREVAIL THROUGHOUT THE REMAINDER OF THE EVENT...POTENTIALLY
IMPROVING LATE WEDNESDAY.
THUNDER...
ALTHOUGH INITIAL CONVECTION HAS BEEN LOW-TOPPED SHOWERS...
ENHANCEMENT ACROSS THE HILL COUNTRY IS INDICATIVE OF INCREASING
INSTABILITY THAT WILL SPREAD NORTHWARD TODAY IN WARM ADVECTION
REGIME. TIMING IN TAFS IS BASED ON EARLIER ARRIVAL/IMPACTS AT WACO
THIS MORNING...THEN AFTERNOON THUNDER POTENTIAL AT METRO
TERMINALS.
25
&&
.PREV DISCUSSION... /ISSUED 427 AM CST TUE JAN 8 2013/
MODEL GUIDANCE IS IN GOOD AGREEMENT AND NOW OFFERS A REASONABLE
TRACK FEATURING MORE OF A SMOOTH PENDULUM SWING OF THE UPPER LOW
THROUGH NORTHERN MEXICO TONIGHT BEFORE EJECTING NORTHEAST AND OVER
NORTH CENTRAL TEXAS WEDNESDAY EVENING. THE MODELS HAVE BACKED OFF
THE SLOWER/WOBBLY TRACK THAT TOOK THE LOW WELL WEST OF THE CWA.
THIS MEANS THE SYSTEM WILL BE IN AND OUT MORE QUICKLY...AND
TIMING FOR THE HEAVIEST RAINFALL AND MOST ROBUST CONVECTION NOW
LOOKS LIKE TONIGHT AND WEDNESDAY MORNING. THIS ALSO MEANS THE WARM
SECTOR WILL HAVE LESS TIME TO PENETRATE THE CWA WITH THE SEVERE
THREAT RELEGATED TO THE FAR SE ZONES BETWEEN 3 AM AND 9 AM WED.
ISENTROPIC LIFT HAS BEGUN ACROSS NORTH TEXAS AND CLOUDS WILL
CONTINUE TO THICKEN AND LOWER THROUGH THE DAY. SHOWERS AND AREAS
OF DRIZZLE HAVE ALREADY DEVELOPED ACROSS CENTRAL TEXAS. MODEL
SOUNDINGS REVEAL MUCAPE VALUES OF 100 J/KG NORTH TO 500 J/KG SOUTH
FOR PARCELS NEAR 800MB. THIS MEANS A FEW THUNDERSTORMS WILL
DEVELOP ONCE THE ISENTROPIC LIFT BEGINS ON THE 325K SURFACE
WHICH SHOULD OCCUR AFTER 9AM. SHOWERS/STORMS WILL BECOME NUMEROUS
DURING THE DAY AND SPREAD N/NE. IN THE MEANTIME A DEVELOPING
INVERTED SURFACE TROUGH AND LOW CENTER IN SOUTH TEXAS WILL CAUSE
WINDS TO BACK TO THE NORTHEAST. COLD ADVECTION...CLOUDS AND RAIN
WILL KEEP HIGHS IN THE UPPER 40S WEST TO LOW 50S EAST.
ISENTROPIC LIFT INTENSIFIES SUBSTANTIALLY TONIGHT AS LOW LEVEL
WIND FIELDS INCREASE AND BACK TO THE SOUTHEAST. MOISTURE FLUX AND
THETA-E ADVECTION VALUES ARE VERY HIGH. CONSIDERING THE WARM
CONVEYOR BELT WILL BE TAPPING INTO UNSEASONABLY HIGH PRECIPITABLE
WATER VALUES OF ALMOST 2 INCHES IN THE GULF...THIS WILL ALLOW A
WIDESPREAD AREA OF RAIN TO DEVELOP TONIGHT AND PERSIST INTO
WEDNESDAY MORNING ACROSS NORTH TEXAS IN THE COLD SECTOR. WHILE
RAINFALL RATES WILL LIKELY NOT EXCEED AN INCH PER HOUR...THE
CONTINUOUS RAINS SHOULD HELP GENERATE EXCESSIVE RUNOFF. HEAVY RAIN
EVENTS IN THE COLD SEASON TEND TO PRODUCE MORE RUNOFF THAN IN THE
WARM SEASON. MOST VEGETATION IS DORMANT AND THEREFORE IT DOES NOT
TAKE MUCH OF THE RAIN WATER OUT OF THE SOILS. WE ARE OUTLOOKED IN
SLIGHT RISK FOR EXCESSIVE RAINFALL BY HPC AND HAVE ISSUED A FLASH
FLOOD WATCH FOR AREAS WHERE WE EXPECT 2 TO 4 INCHES OF RAIN. THE
METROPLEX IS ON THE EDGE OR JUST NORTHWEST OF THE HEAVY RAIN AXIS
BUT WE BROUGHT THE WATCH INTO TARRANT/DALLAS/COLLIN COUNTIES
BECAUSE THE URBANIZATION IS MORE SENSITIVE TO HEAVY RAINFALL.
CONCERNING THE SEVERE WEATHER THREAT...A LINE OF STORMS SHOULD
FORM IN SOUTH CENTRAL TEXAS THIS EVENING AND MOVE RATHER SLOWLY
TO THE E/NE INTO OUR FAR SOUTH/SOUTHEAST ZONES AFTER 3 AM.
ALTHOUGH THE WARM SECTOR DOES MAKE IT INTO THE SOUTHEAST ZONES
AHEAD OF THE LINE...IT IS AT THE COOLEST TIME OF THE DAY. THIS
WILL LIKELY LIMIT SURFACE BASED CAPE TO LESS THAN 100 J/KG IF
ANYTHING AT ALL. BECAUSE SHEAR WILL BE HIGH...WE WILL HAVE TO
MONITOR THIS CLOSELY...BUT AT THIS TIME THE SEVERE WEATHER THREAT
LOOKS MORE CONDITIONAL THAN PREVIOUS FORECASTS WHICH HAD THE LINE
MOVING IN DURING THE WARMER AFTERNOON HOURS.
PASSAGE OF THE SURFACE TROUGH WILL BE SUCCEEDED BY DRY SLOT ALOFT
WHICH SHOULD END MOST OF THE RAIN FROM WEST TO EAST DURING THE DAY
WEDNESDAY. A FEW ELEVATED SHOWERS WILL REMAIN POSSIBLE WEDNESDAY
EVENING BUT HAVE LOWERED POPS DUE TO THE FASTER TIMING. SOME WRAP
AROUND CLOUDS WILL AFFECT THE NW ZONES THURSDAY...BUT OTHERWISE
GENERALLY FAIR WEATHER WITH WARMER TEMPS DUE TO SW WINDS. FRIDAY
WILL BE SUNNY AND WARMER WITH HIGHS NEAR 70. THE NEXT FRONT WILL
ARRIVE SATURDAY AND BRING A SLIGHT CHANCE OF CONVECTION OVER THE
EASTERN HALF OF THE AREA. TEMPS WILL COOL INTO THE 30S FOR LOWS
SAT NIGHT...WITH THE UPPER LEVEL PATTERN FAVORABLE FOR SEVERAL
DAYS OF COLD ADVECTION INTO NEXT WEEK. HIGH TEMPS WILL BE CHILLY
SUNDAY INTO MID WEEK...GENERALLY IN THE LOW-MID 40S. GFS HAS
BACKED OFF ON PRECIPITATION SUNDAY WHICH IS WHAT THE OTHER MODELS
WERE FORECASTING...HOWEVER THERE IS A LITTLE MORE EVIDENCE THAT WE
WILL CONTEND WITH POSSIBLE WINTRY PRECIPITATION FOR THE MIDDLE OF
NEXT WEEK WHEN THE UPPER LEVEL PATTERN BECOMES MORE FAVORABLE.
TR.92
&&
.CLIMATE...
IN THE DALLAS/FORT WORTH METROPLEX...24-HOUR RAINFALL (MIDDAY
TODAY TO MIDDAY WEDNESDAY) MAY REACH 3 INCHES. WHEN WAS THE LAST
TIME DFW AIRPORT SAW THAT MUCH PRECIPITATION IN A 24 HOUR PERIOD?
APRIL 8, 2012 (EASTER SUNDAY) - 2.23
MARCH 19-20, 2012 - 4.04
JANUARY 24-25, 2012 - 4.27
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 51 47 56 46 60 / 100 100 100 50 10
WACO, TX 52 49 57 45 64 / 100 100 100 30 10
PARIS, TX 52 47 57 51 60 / 90 100 100 80 10
DENTON, TX 50 45 54 45 59 / 100 100 90 60 10
MCKINNEY, TX 51 47 56 47 59 / 100 100 100 60 10
DALLAS, TX 51 47 56 46 60 / 100 100 100 50 10
TERRELL, TX 52 49 57 50 61 / 100 100 100 60 10
CORSICANA, TX 53 51 58 49 63 / 100 100 100 40 10
TEMPLE, TX 53 49 58 45 65 / 100 100 100 30 10
MINERAL WELLS, TX 48 44 54 42 60 / 90 100 80 50 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH WEDNESDAY
AFTERNOON FOR TXZ094-095-104>107-118>123-133>135-145>148-158>162-
174-175.
&&
$$