Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 210557
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
157 AM EDT TUE OCT 21 2014

.SYNOPSIS...
LOW PRESSURE MOVES INTO THE REGION TONIGHT AND TUESDAY...LOCATING
OFF THE NORTHEAST COAST FOR MUCH OF THE MID TO LATE WEEK PERIOD.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SFC HIGH PRESSURE WAS CENTERED WELL OFF THE COAST THIS EVENING
ALLOWING FOR A RELAXING PRES GRAD ALONG THE COAST AND INLAND WITH
SOUTHERLY WINDS 10 KT OR LESS. MEANWHILE...AN UPPER LEVEL TROUGH DIGS
INTO THE GREAT LAKES/NORTHEAST TONIGHT...WITH A SFC COLD FRONT
REACHING THE SPINE OF THE APPALACHIANS AROUND 12Z TUE.

SHORTWAVE ENERGY ROUNDING THE BASE OF THE TROUGH HAS BEEN
PROVIDING WEAK LIFT SUPPORTING A THIN BAND OF ISOLD SHOWERS ON
RADAR OVER THE WESTERN CWA...HOWEVER DUE TO THE DRY AIR IN PLACE
IN THE LOWER LEVELS MOST OF THE RADAR ARE RESULTING IN VIRGA. BUFR
SOUNDINGS SHOW OVERALL DRY AIRMASS IN PLACE TONIGHT (PW`S AOB
0.75")...SO IT WILL BE HARD TO GET MUCH OF PCPN TO REACH THE
GROUND. THE HRRR TIES TO DEVELOP A THIN BAND OF SHOWERS EAST OF
I-95 AROUND 06Z...BUT THIS APPEARS TO BE OVERDONE. THAT SAID
CANNOT RULE OUT A FEW BRIEF SPRINKLES OVERNIGHT. OVERALL DRY
CONDITIONS ARE EXPECTED THRU TONIGHT WITH SOME INCREASING CLOUD
COVER. THE CLOUD COVER AND LIGHT SW FLOW COULD KEEP SOME AREAS
FROM REACHING FORECAST LOWS KEEPING CONDITIONS MILDER. LOWS
GENERALLY IN THE UPPER WEST TO MID 50S AT THE COAST.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
FLOW AMPLIFIES DURING THE SHORT TERM AS A BLOCKING PATTERN DEVELOPS
OVER ERN CANADA. ADDITIONAL ENERGY DIVES SOUTH OVER THE GREAT
LAKES/OH VALLEY TUES THANKS TO A ~100 KT JET STREAK DIVING SWD
FROM CANADA. AS A RESULT...UPPER LOW PROGGED TO DEVELOP OVER THE
MID-ATLANTIC INTO THE NE STATES LATE TUESDAY. THE UPPER LOW WILL
PROGRESS SLOWLY EWD TUES NIGHT INTO WED...LOCATING OFF THE
DELMARVA COAST LATE WED. WITH THE UPR LOW PIVOTING ACROSS THE
LOCAL AREA TUE/TUE NIGHT...WILL SEE A BETTER CHANCE FOR SHOWERS
DEVELOP ESPECIALLY NORTH/NE WHERE BEST UPWARD MOTION IS
ANTICIPATED. HAVE CHANCE (POPS 25-40%) ALONG AND NE OF A LINE FROM
LKU-OFP-MFV ON TUE...THEN BEST CHANCE (30-50%) MAINLY ALONG THE
VA COAST AND ONTO THE EASTERN SHORE TUE NIGHT. ELSEWHERE...WILL
CARRY NO HIGHER THEN 20% POPS. HIGHS TUE IN THE UPPER 60S NW TO
MID 70S SE. LOWS TUE NIGHT IN THE MID 40S TO MID 50S. MOSTLY
CLOUDY NORTH TO PARTLY CLOUDY SOUTH DURING THIE TIME.

DEEP UPPER TROUGH/CLOSED LOW SLOWLY MOVES EAST AND OFFSHORE WED.
FORECAST SOUNDINGS FAIRLY DRY ALOFT OVER INLAND SECTIONS AS THE
TROUGH/SFC REFLECTION SWING OFFSHORE. WILL THEREFORE KEEP CHC POPS
LIMITED TO AREAS ALONG AND NE OF THE I-64 CORRIDOR WED...WITH
EMPHASIS ON THE NORTHERN NECK AND EASTERN SHORE (30-50% POPS).
COULD END UP BEING DRY OVER FAR SW ZONES. COOLER WED WITH HIGHS
ONLY 60-65.

THE CLOSED LOW MOVES FARTHER NE WED NIGHT INTO THU...LOCATING OFF
THE NEW ENGLAND COAST BY 00Z FRIDAY. ANY LEFTOVER SHOWER CHANCES
BY THEN WILL BE LIMITED TO THE EASTERN SHORE (20%). DECREASING
CLOUDS ARE ALSO EXPECTED ACROSS INTERIOR VA. LOWS WED NIGHT IN THE
LOW 40S TO LOW 50S. COOL AGAIN THU WITH HIGHS 60-65.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
LOW PRESSURE LIFTS TO THE NE THURSDAY NIGHT THROUGH SATURDAY AS
UPPER RIDGING EXPANDS EASTWARD FROM THE CENTRAL US. A WEAK TROUGH
CLIPS THE NRN MID-ATLANTIC SATURDAY NIGHT AND QUICKLY MOVES OFF THE
COAST SUNDAY. MID/UPPER LEVEL RIDGING BUILDS OVER THE ERN US EARLY
NEXT WEEK. OVERALL...DRY CONDITIONS SHOULD PREVAIL THROUGH THE
MEDIUM RANGE PERIOD. HIGH TEMPERATURES SHOULD AVERAGE IN THE MID 60S
TO AROUND 70 FRIDAY AND SATURDAY...AND TREND UPWARD INTO THE UPPER
60S TO LOW 70S SUNDAY...AND POTENTIALLY 70-75 BY MONDAY. LOWS SHOULD
RANGE FROM THE LOW/MID 40S NW...TO THE LOW/MID 50S FOR SE COASTAL
LOCATIONS.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
EXPECT MAINLY VFR CONDITIONS TODAY INTO THIS EVENG OVR THE TAF
SITES...WITH PERIODS OF MID LVL CLOUDINESS...AS A WEAK COLD FRONT
MOVES ACRS THE AREA. LATER TNGT THRU THU...LO PRES WILL INTENSIFY
OFF THE NEW JERSEY AND NEW ENGLAND CSTS. THERE WILL BE A CHC FOR
SHOWERS AND MVFR CIGS...ESPLY OVR NRN AND ERN PORTIONS LATE TNGT
INTO WED NGT. MVFR CIGS MAY LINGER INTO EARLY THU AT SBY. THE LO
PRES SYSTEM WILL MOVE FARTHER AWAY TO THE NE AND HI PRES BLDS IN
FM THE NNW THU NGT INTO SUN.

&&

.MARINE...
10 PM UPDATE...WINDS AND SEAS HAVE INCREASED WELL OFFSHORE (OFF
THE MD COAST) ACCORDING TO BUOY 09. SEAS ARE JUST ABOUT 5 FT (4.9
FT LAST TWO HOURS). WINDS AND SEAS ARE MUCH LESS TOWARD THE COAST.
INCLUDED A STRIP OF 5 FT SEAS (THROUGH 06Z) IN THE ZONES N OF
PARRAMORE ISLAND BUT HOLDING OFF ON SCA FOR NOW.

HI RES MODELS ARE OVERDOING THE WINDS OVER THE BAY. AS AIR
TEMPERATURES COOL...MIXING WILL INCREASE AND WINDS MAY INCREASE
BUT EXPECT THEM TO STAY BELOW SCA CRITERIA.

PREVIOUS DISCUSSION...
SURFACE HIGH PRESSURE SLIDES OFFSHORE TONIGHT...ALLOWING THE WIND
TO REMAIN S/SW. EXPECT SUB-SCA CONDITIONS TO PREVAIL WITH WIND
SPEEDS AVERAGING UP TO 15-20 KT ACRS NORTHERN COASTAL WATERS...AND
GENERALLY 10-15 KT ELSEWHERE. THE NEXT COLD FRONT WILL SLOWLY CROSS
THE COAST LATE TUE AFTERNOON/EVENING...FOLLOWED BY EVENTUAL SCA
CONDITIONS LATER WEDNESDAY INTO WEDNESDAY EVENING AS SFC LOW PRESSURE
THEN DEEPENS OFF THE COAST. THIS SYSTEM IS EXPECTED TO STALL
OFFSHORE THURSDAY THROUGH THE END OF THE WEEK BRINGING A PROLONGED
PERIOD OF SCA CONDITIONS. WITH FLOW BEING OFFSHORE FROM THE
NW...SEAS WOULD TEND TO STAY CAPPED AT 5-6 FT AND TIDAL FLOODING
IS NOT EXPECTED. N/NW FLOW IS EXPECTED TO CONTINUE INTO NEXT
WEEKEND WITH SPEEDS DIMINISHING TO 10-15KT AND SEAS SUBSIDING.

&&

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

&&

$$
SYNOPSIS...JDM
NEAR TERM...JDM/JAO
SHORT TERM...JDM/SAM
LONG TERM...AJZ
AVIATION...TMG
MARINE...AJZ/LSA





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