Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 232110
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
410 PM EST FRI JAN 23 2015

.SYNOPSIS...
LOW PRESSURE OVER THE GULF COAST REGION WILL RAPIDLY LIFT
NORTHEAST ALONG THE SOUTHEAST ATLANTIC COAST TONIGHT...AND PUSH
OFF THE MID ATLANTIC COAST ON SATURDAY. HIGH PRESSURE RETURNS
BRIEFLY ON SUNDAY...TO BE FOLLOWED BY LOW PRESSURE FROM THE
NORTHWEST CROSSING THE REGION SUNDAY NIGHT THROUGH MONDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
CURRENT ANALYSIS REVEALING DEEPENING SFC LOW PRESSURE CENTERED ALONG
THE AL/GA GULF COAST REGION...WITH SFC HIGH OFF THE DELMARVA
COAST. WSW FLOW PREVAILS ALOFT WELL OUT AHEAD OF AMPLIFYING
MID/UPPER LEVEL TROUGH ALONG THE GULF COAST. PRECIP SHIELD HAS
OVERSPREAD MUCH OF THE CWA...BUT DRY AIR IN LOW LEVELS HAS KEPT
THE PRECIP ON THE LIGHT SIDE THUS FAR (JUST A FEW HUNDREDTHS
THROUGH 20Z). THIS DRY AIR HAS ALSO ALLOWED THE RAIN TO BE MIXING
WITH SLEET WITH SFC TEMPERATURES AS HIGH AS 40 F (AND DEW PTS IN
THE 20S). NO IMPACTS WILL OCCUR AS THE DEW PTS ARE NOT LOW ENOUGH
TO COOL THE TEMPS DOWN TO BELOW FREEZING (GENLY EXPECTING TEMPS TO
DROP TO 33-36 F ALONG/WEST OF I-95 AND ACRS THE NRN TIER OF ERN VA
AND THE MD ERN SHORE THROUGH EARLY EVENING. WILL GO WITH A
RAIN/SLEET MIX ACRS NW/NRN 1/2 OF CWA THROUGH EARLY EVENING.

FOR TONIGHT...MAIN CONCERN WILL NOT BE WINTRY PRECIP...BUT RATHER
THE POTENTIAL FOR MODERATE TO HEAVY RAIN. FOLLOWING A BLEND OF WPC
AND SREF GUIDANCE FOR RAIN OVERNIGHT YIELDS TOTALS OF 1.00 TO
1.50" THROUGH 12 Z...WITH AN ADDITIONAL 0.25-0.50" EXPECTED DURING
THE DAY SAT. THIS AS STRONG UPPER JET/RRQ FORCING INCREASES DEEP
UVM LATER THIS EVENING AND OVERNIGHT. GFS/NAM PROG ~60 KT SOUTHERLY
LOW LEVEL JET BETWEEN 900-800 MB FROM 03-06Z...AND AS SFC LOW
SLIDES OFF THE NC/SE VA COAST BETWEEN 06-12Z WILL SEE RAPID
CYCLOGENESIS AND PRESSURE FALLS. HAVE ADDED MENTION OF HEAVY RAIN
TO ALL AREAS...HIGHEST CONFIDENCE ACRS THE SE ZONES...THOUGH SOME
OF THE MODELS ARE SHOWING A SECONDARY AREA OF HEAVY RAIN OVER NW
SECTIONS DUE TO FRONTOGENESIS. TEMPS OVERNIGHT WILL BE STEADY IN
THE MID-UPPER 30S MOST AREAS...BUT WILL LIKELY RISE A BIT THROUGH
THE 40S OVER FAR SE VA/NE NC. DRY SLOT ENTERS AREAS WEST OF I-95
PRIOR TO DAYBREAK SO WILL RAMP POPS DOWN AFTER 06Z-09Z THERE.

GIVEN TRACK OF SFC LO PRES ON MDLS THROUGH CSTL NE NC THEN OUT TO
SEA...CONCERN ON SAT WILL BE DRY SLOT ARRIVING FM THE
SW...RESULTING IN BULK OF PCPN WINDING DOWN/ENDING BEFORE ANY AIR
COLD ENOUGH FM THE PCPN ENDING AS MIXED SN/RA OR ALL SN (IN THE
AFTN/EVE). GFS/NAM/ECMWF ALL SHOW A BRIEF PERIOD OF STRONGER
FORCING AS THE UPPER SYSTEM PUSHES THROUGH THE REGION SAT AFTN.
WHILE BNDRY LAYER WOULD BE FAIRLY WARM...COULD SEE A BRIEF PERIOD
WHERE PRECIP COULD TURN TO SNOW OR RAIN/SNOW MIX IN HIGHER PRECIP
RATES. THUS WILL KEEP MENTION OF RA/SN IN BY AFTN ACRS N/W 1/2 OF
THE CWA GIVEN THE UNCERTAINTY. HIGHS SAT 40-45 F (ARND 50 F CSTL
NE NC). IT COULD BE A TAD WARMER THAN THIS IF SKIES CLEAR A LITTLE
EARLIER AND TEMPS RISE A FEW DEGREES PRIOR TO SUNSET.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
LATEST 12Z SUITE OF THE GFS/NAM/ECMWF CONTINUE TO TREND FASTER/MORE
PROGRESSIVE AND THE W/NW FLOW ALOFT SHOULD ALLOW FOR RAPID DRYING OF
ANY LEFTOVER MOISTURE. WILL FORECAST DRY CONDITIONS UNDER PARTLY
CLOUDY TO MOSTLY CLEAR SKIES SAT NIGHT OTHER THAN A CHC FOR SNOW BRIEFLY
IN THE EVENING ON THE MD ERN SHORE/NRN NECK. LOWS 30-35 F. PARTLY
SUNNY WITH HIGHS IN THE LWR 50S S TO THE MID 40S N ON SUN IN
ADVANCE OF NEXT CLIPPER SYSTEM.

MUCH COLDER AIRMASS APPROACHES FROM THE WNW SUN NIGHT INTO MON...AS
CLIPPER SYSTEM TRAVERSES THE CENTRAL/SRN APPALACHIANS SUN NIGHT
AND SLIDES ESE THROUGH SRN VA/NC AND OFFSHORE THROUGH THE DAY MON.
MODELS DIFFER SOMEWHAT AS TO HOW FAST COLD AIR ARRIVES...GFS
SLOWEST/NAM/ECMWF A BIT FASTER ON MON. WILL CARRY HIGH CHC TO
LIKELY POPS AND RAIN CHANGING TO SNOW ON MON. THIS IS BY FAR
LOOKING LIKE OUR BEST CHC FOR ACCUMULATING SNOW THUS FAR THIS
WINTER FOR MUCH OF THE CWA. HIGHS MON IN THE 40S S TO THE 30S N
(WITH TEMPS LIKELY TO BE STEADY OR SLOWLY FALL THROUGH THE DAY). STAY
TUNED.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLY AMPLIFIED/MERIDIONAL FLOW WILL PERSIST THRU THE EXTENDED
PERIOD...CHARACTERIZED BY A DEEP/ANOMALOUS NRN STREAM UPPER TROUGH
OVER THE ERN CONUS AND BLOCKY FLOW OVER THE WRN ATLANTIC. TO BEGIN
THE EXTENDED...LOW PRESSURE PROGGED TO LIFT AWAY FROM THE
MID-ATLANTIC COAST TUES MORNING AS THE NEXT IN A SERIES OF NRN
STREAM SHORTWAVES DIGS OVER THE CNTRL CONUS. SHORTWAVE DIGS OVER THE
TN/KY VALLEYS AND INTO THE CAROLINAS TUES MORNING. ASSOCIATED AREA
OF LOW PRESSURE DROPS SOUTH OF THE REGION. HEIGHT FALLS IN TANDEM
WITH MOIST SOUNDINGS WILL RESULT IN ADDITIONAL PRECIP THRU MON
NIGHT. MODELS HAVE COME INTO BETTER AGREEMENT...SO HAVE INCREASED
POPS TO SOLID CHANCE POPS...ESPECIALLY NORTH AND EAST OF RICHMOND.
THERMAL PROFILES INDICATE THAT PRECIP WILL TRANSITION TO
PREDOMINATELY SNOW THRU THE NIGHT...REACHING SE VA/NE NC AFTER
MIDNIGHT. STILL TOO EARLY TO KNOW FOR SURE...BUT LIGHT ACCUMULATIONS
ARE POSSIBLE. WILL CARRY SLIGHT CHANCE-LOW END CHANCE POPS TUES AS
THE SHORTWAVE DIGS SOUTH OF THE LOCAL AREA...BUT EXPECT BRUNT OF
MEASURABLE PRECIP TO BE OFFSHORE. THEREAFTER...MODELS IN GOOD
AGREEMENT WITH PUSHING THE TROUGH AXIS OFFSHORE LATE TUES NIGHT-WEDS
MORNING. ANOTHER AREA OF LOW PRESSURE EXPECTED TO FORM OFFSHORE TUES
NIGHT...BUT INCREASING NWLY FLOW WILL LIMIT THE AMOUNT OF MOISTURE
OVER THE REGION. SFC HIGH PRESSURE WILL BEGIN TO BUILD INTO THE
REGION IN CONFLUENT FLOW ALOFT WEDS-WEDS NIGHT...RESULTING IN DRY
CONDITIONS. NRN AND SRN STREAM ENERGY APPROACHES THE REGION
THURS...AS AN ASSOCIATED COLD FRONT REACHES THE CNTRL APPALACHIANS
LATE THURS-THURS NIGHT. MAINTAINED SLIGHT CHANCE POPS ACROSS THE
NORTH THURS NIGHT.

BELOW NORMAL TEMPS PERSIST THRU THE PERIOD WITH HIGHS TUES-WEDS IN
THE MID-UPPER 30S. TEMPS REBOUND THURS-FRI INTO THE LOW-MID 40S.
COLDEST NIGHT WILL BE TUES NIGHT...WITH LOWS IN THE UPPER TEENS TO
LOW 20S.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
A LOW PRESSURE SYSTEM DEVELOPING OVER THE SOUTHEASTERN US WILL SLIDE
NE THIS AFTERNOON AND TONIGHT.  THIS WILL PUSH GULF MOISTURE INTO
THE AREA AND OVER RUN COOL DRY AIR AS HIGH PRESSURE EXITS THE
REGION.  WILL GRADUALLY SEE CONDITIONS DETERIORATE LATE THIS
AFTERNOON AND TONIGHT FROM VFR TO IFR/LIFR OVERNIGHT WITH LOW
CEILINGS AND REDUCE VISIBILITIES.

BY SATURDAY MORNING...THE SFC LOW WILL BE OFF THE DELMARVA COAST AND
SHOULD BEGIN TO RAPIDLY INTENSIFY.  THIS WILL TURN THE WINDS MORE
NORTH AND NORTHWEST DURING THE DAY AND PULL THE REMAINING MOISTURE
OFF THE COAST.  AS THE UPPER LOW PULLS ACROSS THE AREA SATURDAY
AFTERNOON...SOME OF THE LINGERING SHOWERS COULD CHANGE TO
SNOW...WHICH WOULD CAUSE MORE MVFR TO IFR CONDITIONS.  ONCE THE
MOISTURE CLEARS SAT EVENING...WILL SEE A RETURN TO VFR CONDITIONS
SAT NIGHT THROUGH SUNDAY.

ANOTHER WEATHER SYSTEM WILL IMPACT THE AREA MONDAY INTO TUESDAY.
THIS COULD AGAIN CAUSE SOME MVFR TO IFR CEILINGS ALONG WITH A CHANCE
FOR SOME WINTRY PRECIPITATION...MOST LIKELY RAIN SHOWERS CHANGING TO
SNOW SHOWERS LATER MONDAY INTO TUESDAY.

&&

.MARINE...
HIGH PRESSURE REMAINS OVER THE WATERS THIS AFTERNOON WITH ELY WINDS
AOB 10 KT. WAVES GENERALLY 1-2 FT AND SEAS 2-3 FT. HIGH PRESSURE
PUSHES OFFSHORE THIS EVENING AS LOW PRESSURE LIFTS NEWD OVER THE SE
COASTAL PLAINS. GRADIENT WINDS RAMP UP AS WINDS BECOME SELY IN
ADVANCE OF THE LOW. LOW PRESSURE WILL LIFT OVER THE LOWER BAY LATE
TONIGHT...PULLING AWAY FROM THE COAST SAT MORNING. WHILE WAA WILL
ACCOMPANY THE INCREASING LOW LEVEL WINDS...A BRIEF PERIOD OF SCA
CONDITIONS ARE EXPECTED IN THE BAY/SOUND/COASTAL WATERS WITH THE
STRONGEST PRESSURE GRADIENT AS THE LOW LIFTS OVER THE WATERS EARLY
TONIGHT. A BRIEF LULL IN SCA WINDS EXPECTED AS THE LOW LIFTS OVER
THE WATERS LATE TONIGHT. AS THE LOW LIFTS NEWD AWAY FROM THE WATERS
AND THE TRAILING COLD FRONT SWEEPS THRU THE AREA...LOW LEVEL CAA
WILL RESULT IN A NWLY SURGE SAT MORNING THRU SAT AFTERNOON. SEAS
WILL BUILD FIRST IN THE SRN WATERS...REACHING 4-6 FT THIS
EVENING...AND 4-6 FT IN THE NRN WATERS AFTER MIDNIGHT. WINDS BECOME
MORE WLY SAT AFTERNOON AS LEE SIDE TROUGHING DEVELOPS AND CAA WANES.
SCA HEADLINES FOR THE BAY/RIVERS/SOUND RUN THRU THE DAY SAT. SEAS
REMAIN 4-6 FT (UP TO 7 FT IN THE NRN WATERS) THRU THE
DAY...SUBSIDING THRU SAT EVENING. HIGH PRESSURE BUILDS OVER THE SE
STATES SUN WITH SUB-SCA CONDITIONS OVER THE WATERS. LOW PRESSURE
PROGGED TO CROSS THE WATERS MON...INTENSIFYING AS IT MOVES OFFSHORE.
SCA CONDITIONS ARE EXPECTED MON AFTERNOON INTO TUES. LOW END GALES
POSSIBLE OVER THE COASTAL WATERS. STRONG NWLY WINDS WILL PERSIST
THRU TUES NIGHT AS THE WATERS REMAIN BTWN LOW PRESSURE OVER THE WRN
ATLANTIC AND HIGH PRESSURE BUILDING OVER THE OH VALLEY.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM TO 7 PM EST SATURDAY FOR
     ANZ635>638.
     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 PM EST
     SATURDAY FOR ANZ630>634.
     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 1 AM EST
     SUNDAY FOR ANZ654-656-658.
     SMALL CRAFT ADVISORY FROM 1 AM SATURDAY TO 4 AM EST SUNDAY FOR
     ANZ650-652.

&&

$$
SYNOPSIS...LKB
NEAR TERM...LKB
SHORT TERM...LKB
LONG TERM...SAM
AVIATION...ESS
MARINE...SAM






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