Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 171340
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
940 AM EDT THU APR 17 2014

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER NEW ENGLAND WILL SLOWLY PUSH OFF TO
THE CANADIAN MARITIMES THIS AFTERNOON THROUGH FRIDAY...MAINTAINING
A COOL NORTHEAST FLOW ACROSS THE LOCAL AREA. A SLOW MOVING LOW
PRESSURE SYSTEM WILL PERSIST OFF THE SOUTHEAST COAST OVER THE
WEEKEND...AS HIGH PRESSURE BUILDS SOUTH FROM THE GREAT LAKES.

&&

.NEAR TERM /THROUGH TONIGHT/...
SFC ANALYSIS REVEALS A STRONG/1044 MB HIGH CENTERED OVER THE ST
LAWRENCE VALLEY RIDGING SOUTH INTO THE MID ATLC. CLEAR SKIES
PREVAIL...BUT WITH LOW STRATUS NOT FAR OFF THE COAST AND SLOWLY
PUSHING TO THE WEST. THE STRATUS OFF THE COAST HAS NOT MADE MUCH
PROGRESS TO THE EAST EXCEPT OVER THE MARYLAND EASTERN SHORE
UPDATED THE GRIDS TO INDICATE A SLOWER INCREASE IN THE CLOUDS WITH
PLENTY OF SUNSHINE EXPECTED THIS MORNING AND CONTINUING THIS
AFTERNOON FROM INTERSTATE 95 AND WEST. HIGH THIN CLOUDS ADVECTING
FROM THE SOUTH.

EXPECT HIGHS MAINLY 50-55 F NEAR THE COAST (LOCALLY UPPER 40S IN
A FEW SPOTS ON THE ERN SHORE) TO 55-60 F WELL INLAND.

FOR TONIGHT...TRENDS IN MODELS SUGGEST A BIT LESS IN THE WAY OF
CLOUD COVER SO HAVE DROPPED MINS A FEW DEGREES FROM PREVIOUS
FORECAST. AIRMASS WILL CONTINUE TO MODIFY SO EVEN WITH MAINLY
CLEAR SKIES WELL INLAND DO NOT EXPECT TEMPS TO DROP TO 32
F...ALTHOUGH IT MAY BE CLOSE IN SOME AREAS WEST OF I-95 SO WILL
MENTION THIS IN THE HWO. OTHERWISE...LOWS MAINLY 35-40 F...EXCEPT
40-45 F NEAR THE COAST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
MODELS AGREE WITH TROUGH PUSHING A BIT CLOSER TO THE LOCAL AREA
(ASSOCIATED WITH A SFC LOW OVER GA/FL) FRI INTO EARLY SAT. IN MID
LEVELS THIS IS IN ASSOCIATION WITH SOME SOUTHERN STREAM ENERGY MOVING
ALONG ACROSS THE SOUTHERN US. THIS ENERGY IS NOT WELL HANDLED BY
ANY OF THE MODELS, SO PLENTY OF UNCERTAINTY REMAINS. FOR NOW, HAVE
LEANED MORE TOWARD THE DRIER NAM/ECMWF (GFS IS AN OUTLIER IN
BRINGING DEEPER MOISTURE INTO SOUTHERN PORTIONS OF THE CWA FRI
NIGHT/SAT). STILL...WILL BRING SLIGHT CHANCE POPS IN FOR FRIDAY NIGHT
OVER THE SOUTHERN/SE 1/3 OF THE AREA, WITH CHANCE POPS OVER PARTS
OF NORTHEAST NORTH CAROLINA.

TEMPERATURES WILL SLOWLY MODERATE THROUGH THE PERIOD. GENERALLY
FOLLOWED MOS GUIDANCE, WHICH KEEPS MOST MINS IN THE 40S THURSDAY
NIGHT AND HIGHS ON FRIDAY BACK INTO THE UPPER 50S TO LOWER 60S.
BY SAT AFTN ALL MODELS AGREE ON A WEAK FRONT CROSSING THE AREA
WITH HIGH PRESSURE REBUILDING FROM THE WEST. THIS WILL CLEAR THE
SKIES ACROSS THE AREA AS IT PUSHES THE TROUGH FARTHER OFF THE
COAST. LOWS FRIDAY NIGHT WILL BE IN THE 40S WITH HIGH TEMPERATURES
ON SATURDAY GETTING BACK TO THE MID 60S SE TO AROUND 70 F NW.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A LONG AREA OF HIGH PRESSURE MOVING ACROSS SOUTHEAST CANADA WILL
EXTEND INTO THE ERN GREAT LAKES AND OH/TN VALLEYS SAT NIGHT.
MEANWHILE...A COASTAL LOW OFF THE SOUTHEAST COAST IS NOW EXPECTED
TO STAY SHUNTED WELL SOUTH OF THE AREA SAT NIGHT AND THEN TRACK NE
WELL OFF THE CAROLINA COAST THROUGH SUN. THE STRETCHED OUT SFC
HIGH AND ASSOCIATED MID/UPPER RIDGING WILL PASS OVER THE MID
ATLANTIC REGION SUN INTO EARLY MON. THE SFC HIGH THEN SLIDES OFF
THE COAST DURING THE DAY AS THE MID/UPPER RIDGING FLATTENS. A
RELATIVELY FLAT (WEST TO EAST ORIENTED) FRONTAL BOUNDARY SAGS DOWN
INTO THE AREA MON NIGHT INTO TUE...MOVING OFFSHORE BY WED MORNING.
WEAK SHORTWAVE ENERGY AND A SUBSEQUENT SFC LOW TRAVELING ALONG
THIS BOUNDARY MAY BRING ANOTHER SHOT OF PRECIPITATION TO THE AREA
ON MON/TUE. GFS PRECIP-GENERATION AND GENERAL MOVEMENT CONTINUES
TO BE AGGRESSIVE/FAST VERSUS THE ECMWF. HAVE THEREFORE TRIED TO
SPLIT THE DIFFERENCE WITH THE POP FORECAST...LEANING TWD SLIGHTLY
SLOWER TIMING TO THE ONSET OF PRECIP MON NIGHT AND LIMITING
OVERALL COVERAGE ON TUE TO NO HIGHER THAN 40 PERCENT.

TEMPERATURES ARE EXPECTED TO BE STRAIGHT-FORWARD SAT NIGHT THROUGH
SUN NIGHT AS HIGH PRESSURE CROSSES THE REGION. EXPECT LOWS NEAR
NORMAL BOTH NIGHTS IN THE 40S (LOWER 50S POSSIBLE IMMEDIATE SE VA/NE
NC COASTS). HIGHS SAT/SUN RANGE FROM ROUGHLY 65 DEGREES FAR NE TO 70
DEGREES SW. AS THE FLAT FRONTAL BOUNDARY STARTS TO SAG INTO THE MID
ATLANTIC STATES MON THROUGH WED...THE TEMP FORECAST BECOMES TRICKY
IN REGARD TO WHERE EXACTLY THE WARM SECTOR DEVELOPS. WITH PRECIP
EXPECTED TO MOVE INTO THE AREA AT SOME POINT MON NIGHT...INCREASING
CIRRUS DURING THE DAY MON SHOULD KEEP HIGH TEMPS IN THE UPPER 60S
WEST OF I-95 WITH WARMER TEMPS IN THE LOWER 70S EAST OF I-95
(MID-UPPER 60S MD/VA EASTERN SHORE). HIGHS TUE SHOULD BE IN THE
LOW-MID 70S INLAND AND IN THE UPPER 60S NEAR THE IMMEDIATE CHES
BAY AND ATLANTIC COASTS. THE WARMING TREND CONTINUES WITH HIGHS
ON WED IN THE MID 70S INLAND TO UPPER 60S AT THE IMMEDIATE COAST.
LOW TEMPERATURES AREAWIDE ON MON/TUE/WED NIGHTS SHOULD ALSO BE
WARM WITH READINGS IN THE 50S (OR ABOUT 10 DEGREES ABOVE NORMAL).

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
A MAINLY CLEAR SKY IS EXPECTED THRU EARLY THIS MORNING. SFC RIDGING
FM THE NE WILL THEN HELP TO BRING IN STRATOCU CLOUDS...WHICH COULD
GO TO MVFR CIGS...OVER SE VA/NE NC TAF SITES (ORF/ECG) DURING
TODAY...DUE TO MOIST ONSHORE FLOW. NE WINDS MAY BE GUSTY ONCE
AGAIN AT THESE SITES ALSO FM LATER THIS MORNING INTO THIS EVENG.

OUTLOOK...DUE TO CONTINUED RATHER STRONG HI PRES OVER NEW ENGLAND
AND THE CANADIAN MARITIMES...THE CHC FOR MVFR CONDITIONS WILL
INCREASE THRU FRI NGT...ESPLY ACRS SE PORTIONS. THERE WILL ALSO
BE A CHC FOR SHOWERS LATE FRI AND FRI NGT.

&&

.MARINE...
SCA FLAGS REMAIN IN EFFECT THROUGH EARLY THIS AFTN FOR THE ERN VA
RIVERS AND NRN CHES BAY ZNS...AND THROUGH THIS EVENING FOR THE SRN
CHES BAY. HI PRES WILL SLIDE ACRS NEW ENGLAND AND INTO THE
CANADIAN MARITIMES TODAY THRU FRI...MAINTAINING NE WINDS OVR THE
WTRS. THE PERSISTENT ONSHORE FLOW WILL CAUSE SEAS TO REMAIN AT OR
ABOVE 5 FT FOR ALL CSTL WTRS THRU AT LEAST LATE FRI NGT. FRI NGT
THRU MON...LO PRES WILL TRACK ACRS FLORIDA...THEN ENE WELL OFF THE
MID ATLC CST. WHILE...HI PRES WILL BLD FM THE NRN GRT LAKES EWRD
ACRS NEW ENGLAND AND OFF THE CST. THIS SCENARIO WILL MAINTAIN
GENERALLY N OR NE WINDS 10 TO 15 KT ACRS THE WTRS FRI NGT THRU
MON.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR ANZ630-
     631-635>638.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ632-634.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR ANZ633.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ650-652-
     654-656-658.

&&

$$
SYNOPSIS...LKB
NEAR TERM...LKB/LSA
SHORT TERM...LKB/JAB
LONG TERM...BMD
AVIATION...TMG
MARINE...TMG






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