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Area Forecast Discussion
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000
FXUS61 KAKQ 211533
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1033 AM EST SUN DEC 21 2014

.SYNOPSIS...
HIGH PRESSURE MOVES ACROSS THE AREA TODAY...THEN OFF THE COAST TONIGHT.
LOW PRESSURE MOVES NORTHEAST OUT OF THE GULF OF MEXICO AND UP ALONG 
THE CAROLINA COAST MONDAY INTO TUESDAY. A STRONG COLD FRONT WILL CROSS
THE AREA WEDNESDAY NIGHT. HIGH PRESSURE RETURNS BY CHRISTMAS DAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST ANALYSIS DEPICTS ~1029 MB SFC HIGH PRESSURE CENTERED OVER
DE/MD/ERN VA...WITH A TROUGH OF LOW PRESSURE FROM THE ERN GULF OF
MEXICO TO A POSITION OFF THE SC COAST. SKIES ARE MOSTLY CLOUDY
OVER THE LOCAL AREA (EARLIER CLEAR SKIES ACRS NE NC HAVE SINCE
CLOUDED OVER). LOOKING AT SATELLITE AND 12Z SOUNDINGS AS WELL AS
BUFKIT FORECAST SOUNDINGS...THINK SKIES WILL STAY MAINLY CLOUDY
THROUGH AT LEAST 18Z...WITH PARTIAL CLEARING LATE IN THE AFTN.
HAVE ADJUSTED GRIDS TO GO A LITTLE MORE PESSIMISTIC ON THE CLOUD
COVER TO ACCOUNT FOR THIS. LITTLE CHANGE NEEDED TO
TEMPERATURES...HIGHS AVG AROUND 40 F ON THE ERN SHORE TO THE UPPER
40S OVER SOUTH CENTRAL VA AND NE NC.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
DRY THIS EVENING. CLOUDS QUICKLY THICKEN S-N LATE EVE AND EARLY 
MORNING IN RESPONSE TO LOW PRES MOVG NE FROM GOM. TRICKY PART OF FCST 
WILL BE HOW FAST PCPN OVERSPREADS THE FA AND WHAT FORM P-TYPE WILL 
BE OVR THE PIEDMONT AS IN-SITU WEDGE DVLPS. DESPITE SOME TIMING 
DIFFERENCES LTST MODELS IN GNRL AGREEMENT THAT PCPN OVERSPREADS THE 
AREA S-N BTWN 06Z-12Z. LL THICKNESSES WARM ENUF FOR LIQUID PCPN E OF 
I95 BUT REMAIN MARGINAL W OF I95. BUFKIT SNDGS CONT TO SHOW A NARROW 
LAYER OF BLO FREEZING SFC TMPS THRU 15Z OR SO ACROSS THE PIEDMONT. 
THNK P-TYPE WILL START OFF AS A FEW HRS OF SLEET W OF I95 AND N OF
RT 460 LATE TONIGHT DUE TO EVAP COOLING WITH TMPS NEAR FREEZING.
MAY EVEN SEE SOME WET SNOWFLAKES OVER CNTYS NW OF RIC...BUT NOT
SGNFCNT ENUF TO MENTION IN FCST ATTM. QPF LOOKS MINIMAL THRU
12Z...SO ABT THE ONLY ACTION NEEDED AT THIS POINT IS A MENTION IN
HWO. RAIN SRN CNTYS. MIN TMPS MAY LIKELY OCCUR IN THE EVENING WITH
STDY READINGS AFTR MIDNITE. LOWS U20S-M30S.

WEDGE BEGINS TO WEAKEN MON MORNING AS HIGH PRES MOVES INTO ERN CANADA.
THE NORMALLY COLDER CNTYS WILL LIKELY STAY NEAR 32 DEGREES THRU 15Z
OR SO AS THE PCPN OVERSPREADS THE ENTIRE FA. EXPECT A QUICK TRANSITION
OVER TO ALL RAIN MOST AREAS JUST AFTR 12Z EXCEPT FOR LOUISA/FLUVANNA/
WRN GOOCHLAND/NRN CUMBERLAND CNTYS WHERE A PERIOD OF MIXED SLEET/FZ
RAIN SHUD CONT THRU AT LEAST 15Z BEFORE TMPS INCH ABV 32 F. THESE
ARE THE AREAS WHERE AN ADVISORY MAY BE NEEDED MON MORNING FOR MINIMAL
IMPACT AS TMPS HOVER ARND 32 F. AREAS FROM CAROLINE/NRN HALF OF NRN
NECK CNTYS ON EAST TO DORCHESTER/WICOMICO MD MAY START OFF AS A
RAIN/SLEET MIX AT THEN QUICKLY GO OVR TO RAIN. RAIN THEN BECOMES
WIDESPREAD MON AFTRN AS THE BULK OF LIFT/MSTR TRACKS ACROSS THE
FA. A RATHER COLD RAIN AS TMPS STRUGGLE TO GET OUT OF THE 30S
PIEDMONT...40-45 EAST TOWARD THE ERN SHORE & SERN CHES BAY...
M40S-L50S SERN VA/NC.

LOW PRESSURE PROGGED TO LIFT NE ALONG THE CAROLINA COAST MONDAY NIGHT
WITH STDYST PCPN ENDING SW-NE BY 06Z. SNDGS INDCTG ENUF MSTR FOR LGT
RAIN / DRIZZLE THRU THE OVRNITE HRS. TMPS STDY IN THE M30S NW TO M40S
SE. QPF 1/4 TO 1/2 IN.

MID-LEVEL RIDGING BRIEFLY BUILDS INTO THE REGION TUESDAY. HOWEVER... 
MOIST EASTERLY FLOW WILL PREVAIL. KEPT LOW CHC (30%) POPS THRU THE 
DAY ALTHROUGH SOME DRIZZLE MAY LINGER THROUGH THE MORNING HRS. BIG 
TMP DIFFERENCES SEEN IN MOS DATA WHERE NAM IS SOME 5-10 DEGREES 
COLDER THAN THE GFS. GIVEN MODELS MAINTAIN AN ERLY SFC FLOW...WILL 
SPLIT THE DIFFERENCE FOR NOW AND GO WITH HIGHS FROM THE M-U40S OVR
THE PIEDMONT TO M-U50S CSTL AREAS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A COASTAL LOW JUST OFF THE MID ATLANTIC COAST CONTINUE TO WASH OUT 
TUE NIGHT AS A WARM FRONT STARTS TO LIFT NORTH THROUGH THE REGION. 
MEANWHILE...A VERY STRONG AND VIGOROUS SFC LOW DEEPENS OVER THE 
OH/TN VALLEYS AND PUSHES A STRONG COLD FRONT TWD THE AREA. INITIAL 
PUSH OF STRATIFORM PRECIPITATION ASSOCIATED WITH THE WARM FRONT TUE 
NIGHT WILL LIKELY GIVE WAY TO MORE SHOWERY PRECIPITATION AS THE MID 
ATLANTIC REGION BECOMES WARM-SECTORED AHEAD OF THE APPROACHING COLD 
FRONT. THE SFC PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY ON WED AS 
THE PARENT LOW DEEPENS OVER THE GREAT LAKES AND A STRONG JET STREAK 
(90-150 KT) NOSES INTO THE REGION FROM THE SSW. HIGHS SHOULD RANGE 
FROM 60-65 NW AND MD/VA LOWER EASTERN SHORE TO 65-69 FROM ROUGHLY 
RICHMOND TO SE VA/NE NC. IN ADDITION TO DEWPOINTS APPROACHING 60 
DEGREES ACROSS THE SERN HALF OF THE CWA...A THETA-E RIDGE IS 
EXPECTED TO SURGE NWD ALONG THE SE WED MORNING INTO THE SRN MID 
ATLANTIC COAST BY WED AFTN/EVENING. THE COMBINATION OF THESE 
FEATURES/CONVECTIVE PARAMETERS MEANS THAT A SLIGHT CHANCE FOR 
THUNDERSTORMS HAS BEEN ADDED TO THE FORECAST ACROSS SE VA AND NE NC 
DURING THE AFTN/EARLY EVENING HOURS. THE FRONT EXITS THE REGION LATE 
WED NIGHT AND PRECIP WILL TAPER OFF FROM WEST TO EAST...COMING TO AN 
END EARLY THU MORNING. 

THE UPPER TROUGH ASSOCIATED WITH THE GREAT LAKES SFC LOW SWINGS 
THROUGH THE REGION LATE WED NIGHT THROUGH THU AFTN. UPPER LEVEL 
INSTABILITY AND ABUNDANT SFC MOISTURE FROM RECENT PRECIPITATION 
SHOULD KEEP SCT-BKN CUMULUS OVER THE AREA THROUGH THE DAY ON THU. 
CAA OCCURRING BEHIND THE COLD FRONT AND A CONTINUED TIGHT SFC 
PRESSURE GRADIENT WILL RESULT IN GUSTY WSW WINDS OF 20-25MPH WITH 
GUSTS AROUND 35MPH...AND SHOULD BE FAIRLY UNIFORM ACROSS THE REGION. 
THE GUSTY WINDS SHOULD DECOUPLE BY THU EVENING. OVERALL CONDITIONS 
FRI THROUGH THE WEEKEND SHOULD BE DRY. A LEE TROUGH FORMS ACROSS THE 
AREA ON FRI AND A WEAK CAD WEDGE DEVELOPS. THE PRESSURE GRADIENT 
RELAXES BRIEFLY FRI/FRI NIGHT AS HIGH PRESSURE BUILDING OVER THE SE 
STATES EXTENDS UP INTO THE MID ATLANTIC REGION. MEANWHILE...A BROAD 
UPPER TROUGH PUSHES A DRY COLD FRONT ACROSS THE REGION ON SAT WHICH 
WILL USHER MUCH COLDER 850MB TEMPS OVER THE AREA (-5 TO -15C). CAA 
AND A RE-TIGHTENING OF THE SFC PRESSURE GRADIENT WILL BRING A RETURN 
TO BREEZY SW WINDS ON SAT AND BREEZY NW WINDS ON SUN BEHIND THE NEXT 
COLD FRONTAL PASSAGE.

&&

.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS AND LIGHT WINDS EXPECTED TO CONTINUE THROUGH THE
12Z TAF PERIOD. BKN-OVC CLOUDS AROUND 7K FT WILL SLOWLY ERODE
THROUGH LATE MORNING/EARLY AFTN. NEXT BATCH OF PCPN WILL BEGIN TO
ARRIVE FROM SOUTH TO NORTH EARLY MON MORNING.

OUTLOOK...A SERIES OF LOW PRESSURE SYSTEMS AND COMPLEX FRONTAL 
BOUNDARIES WILL BRING CHANCES FOR RAIN AND PERIODS OF LOW CEILINGS 
AND VISIBILITIES MONDAY THROUGH WEDNESDAY. A COLD FRONT PASSES 
THROUGH WEDNESDAY NIGHT WITH VFR CONDS AND DRY WEATHER THURSDAY.

&&

.MARINE...
N-NE WINDS AOB 10 KT WILL PREVAIL TODAY WITH HIGH PRESSURE IN PLACE. 
WINDS TURN MORE EASTERLY TONIGHT AND INCREASE TO 10-15 KT MOST AREAS 
AS LOW PRESSURE ORGANIZING OFF THE SOUTHEAST COAST SLOWLY PUSHES 
NORTH. THE SFC LOW CONTINUES TO MOVE NORTHEAST OF THE NC COAST ON 
MONDAY...BUT WEAKENS BY LATE MONDAY/MONDAY NIGHT. WINDS WILL GENERALLY 
REMAIN E-NE AOB 15 KT ALL WATERS DURING THIS TIME...BUT TENDING TO 
BECOME MORE NORTHERLY AOB 10 KT BY EARLY TUES MORNING. LATEST 
GUIDANCE INDICATES POTENTIAL FOR SEAS TO BUILD TO AROUND 5 FT OUT 20 
NM LATE MON/MON EVE ACROSS THE SOUTHERN COASTAL WATERS. CONFIDENCE 
NOT HIGH ENOUGH TO ISSUE A 3RD PERIOD SCA ATTM.

LIGHT NW WINDS EXPECTED TUES AS HIGH PRESSURE REMAINS IN PLACE OVER 
THE MID-ATLANTIC...AND THE NEXT LOW PRESSURE SYSTEM ORGANIZES OVER 
THE DEEP SOUTH. WINDS TURN E-SE TUESDAY NIGHT AND GRADUALLY BEGIN TO 
INCREASE AS A WARM FRONT LIFTS NORTH THROUGH THE AREA. A STRONG 
COLD FRONT APPROACHES THE WATERS FROM THE WEST ON WEDNESDAY WITH 
WINDS BECOMING SOUTHERLY AND INCREASING TO SCA THRESHOLDS (SAVE THE 
RIVERS). THE FRONT QUICKLY SWEEPS THROUGH THE AREA WED NIGHT AND 
OFFSHORE EARLY THURSDAY. WINDS REMAIN ABOVE SCA LEVELS THRU LATE 
THURSDAY WHILE BECOMING SW THEN W. HIGH PRESSURE RETURNS THU NIGHT 
INTO THE START OF NEXT WEEKEND FOR IMPROVED CONDITIONS. SEAS WILL 
GENERALLY BUILD TO 5-7 FT ON WED BEFORE SUBSIDING AGAIN LATE THU. 
WAVES WILL REACH 4 FT ON THE CHES BAY.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...MPR
NEAR TERM...LKB/MPR
SHORT TERM...MPR
LONG TERM...BMD
AVIATION...JDM
MARINE...JDM






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