Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 270029
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
729 PM EST FRI DEC 26 2014

.SYNOPSIS...
HIGH PRESSURE WILL SLOWLY DRIFT OFFSHORE TONIGHT INTO SATURDAY.
LOW PRESSURE TRACKS NORTHEAST THROUGH THE TENNESSEE VALLEY
SATURDAY NIGHT AND ACROSS THE MID ATLANTIC SUNDAY AS A COLD FRONT
APPROACHES FROM THE NORTHWEST. THIS COLD FRONT DROPS THROUGH THE
REGION SUNDAY NIGHT. ANOTHER AREA OF LOW PRESSURE TRACKS ALONG THE
FRONT AND CROSSES THE REGION SUNDAY NIGHT...BEFORE MOVING OFF THE
COAST MONDAY.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
UPDATE...ADDED ADDITIONAL SKY COVER TO ACCOUNT FOR SCT-BKN CIRRUS
STREAMING INTO THE WRN HALF OF THE CWA THIS EVENING AND MADE ONLY
MINOR ADJUSTMENTS TO TEMPS/DEWPOINTS THROUGH TONIGHT.
OVERALL...THE CIRRUS SHOULD HAVE MINIMAL IMPACT ON FALLING TEMPS
TONIGHT. STILL EXPECTING LOWS AROUND 30 INLAND AND IN THE MID-
UPPER 30S FOR SE VA/NE NC COASTAL LOCATIONS.

PREVIOUS DISCUSSION...LATEST SURFACE ANALYSIS FEATURES HIGH
PRESSURE AT THE SFC AND ALOFT OVER THE SOUTHEAST EXTENDING NORTH
INTO THE MID ATLANTIC REGION. SFC HIGH PRESSURE WILL BECOME
ORIENTED ALONG THE MID ATLANTIC/CAROLINA COAST OVERNIGHT.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
HIGH PRESSURE SLOWLY DRIFTS OFFSHORE SATURDAY. LIMITED MIXING AND
A LIGHT SW WIND IS EXPECTED ONCE AGAIN SATURDAY, THOUGH WILL BE
PARTIALLY OFFSET BY WARMING ALOFT. THIS SHOULD YIELD MAXIMA ABOUT
A CATEGORY WARMER THAN THOSE OF TODAY, OR UPPER 50S TO LOW 60S
INLAND, MID TO UPPER 50S COASTAL ZONES AND THE LOWER EASTERN SHORE.
GRIDS WILL AVERAGE OUT SUNNY TO MOSTLY SUNNY, THOUGH WE`LL BEGIN
TO SEE SOME LOWERING MID TO HIGH CLOUDS LATE IN THE DAY AND SAT
NGT AS LOW PRESSURE TRACKS THROUGH THE TENNESSEE VALLEY AND A
COLD FRONT APPROACHES FROM THE NW. LOWS SAT NGT MAINLY IN THE 40S
UNDER A MOSTLY CLOUDY TO OVERCAST SKY.

MODEL GUIDANCE CONTINUES TO BE A BIT SLOWER WITH THE FRONTAL
BOUNDARY, WHICH APPROACHES THE REGION FROM THE TN VLY LATE SAT
THROUGH SUNDAY, DROPPING SOUTH ACROSS THE REGION LATER SUNDAY
THROUGH MONDAY. HAVE INCREASED POP INTO CHC RANGE LATE SAT
NGT/SUNDAY MORNING WITH INITIAL BATCH OF OVERRUNNING MOISTURE
LIFTING NORTH ACROSS THE AREA, WITH RAIN REMAINING LIKELY FOR
MUCH OF THE REGION, ESPECIALLY NORTH/CENTRAL SECTIONS OF THE AREA
SUNDAY AFTERNOON. FOR THAT REASON, HAVE BUMPED POP INTO 50-60%
RANGE ACROSS THE NORTH, TAPERING BACK TO 30-40% SOUTH. HIGHS
SUNDAY IN THE MID 50S TO LOW 60S.

POPS INCREASE TO LKLY RANGE FOR MOST OF OUR AREA SUNDAY NIGHT.
MAIN SHORTWAVE EJECTING EAST ACROSS THE MID-SOUTH WILL INTERACT
WITH THE COLD FRONT AS IT SLOWLY DROPS SOUTH ACROSS THE REGION AND
INTO THE CAROLINAS EARLY MONDAY. DETERMINISTIC MODELS ALL HANDLE
SHORTWAVE ENERGY A LITTLE BIT DIFFERENTLY. CMC IS A BIT MORE
AMPLIFIED THAN EITHER THE 12Z/26 ECMWF OR GFS. HOWEVER, ALL MODELS
ARE CLOSE IN DEPICTING BEST FORCING/UPPER SUPPORT SLIDING ACROSS
THE LOCAL AREA SUNDAY NIGHT. QPF ON THE ORDER OF BETWEEN A HALF
AND THREE-QUARTERS OF AN INCH SUNDAY NIGHT AND EARLY MONDAY. KEPT
LOWS ON THE MILD SIDE WITH ONGOING CLOUDS/PCPN...IN THE LOW 40S
NW TO LOWER 50S SE COASTAL PLAIN. SFC LOW SLIPS OFFSHORE MONDAY
AFTERNOON AND EVENING, WITH SFC FRONT DROPPING SOUTH OF THE AREA
LATE IN THE DAY. POPS RAMP DOWNWARD THROUGH THE DAY, WITH
LINGERING SHOWERS OVER THE EAST DIMINISHING BY SUNSET. CLEARING
WILL LIKELY BE DELAYED WITH ONSHORE FLOW PERSISTING AT LOW LVLS
MONDAY AFTN/EVE. HOWEVER, TEMPS WILL GET OFF TO A MILD START
ACROSS THE SOUTH. THIS COMBINED WITH SHALLOW MIXING WILL RESULT IN
A RATHER SHALLOW DIURNAL CURVE, W/HIGHS ONLY IN THE MID 40S NORTH
TO MID 50S SOUTH, UNDER A MOSTLY CLOUDY TO OVERCAST SKY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
GFS/ECMWF IN GOOD AGREEMENT THROUGH DAY 6 /NEXT THURSDAY/ WITH
REGARD TO OVERALL PATTERN. A COLD ZONAL FLOW WILL PREVAIL ALOFT
ACROSS THE REGION...WITH HIGH PRESSURE BUILDING INTO AND ACROSS THE
AREA FROM MONDAY NIGHT THROUGH THURSDAY OF NEXT WEEK. WEATHER IS
EXPECTED TO BE DRY WITH TEMPERATURES AT OR A BIT BELOW NORMAL FOR
LATE DECEMBER. LOW TEMPS MONDAY NIGHT IN THE 30S...THEN IN THE 25 TO
30 DEGREE RANGE /A BIT WARMER NEAR THE COAST/ TUESDAY NIGHT
THROUGH THURSDAY NIGHT. HIGH TEMPS TUESDAY THROUGH THURSDAY IN THE
40S.

GFS/ECMWF DIVERGE A BIT GOING INTO NEXT FRIDAY...WITH GFS FASTER AND
FURTHER SOUTH WITH LOW PRESSURE AND ASSOCIATED FRONTAL SYSTEM MOVING
ENE/NEWD OUT OF THE PLAINS/MS VLY. REGARDLESS...FRIDAY INTO
SATURDAY NEXT WEEK LOOK TO BE UNSETTLED...WITH TEMPERATURES WARMING
TO NEAR NORMAL FOR HIGH TEMPS ON FRIDAY.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE CENTERED OVER THE REGION IS PROVIDING VFR CONDITIONS
AREA WIDE AND IT IS EXPECTED TO REMAIN IN CONTROL OF THE REGIONS
WEATHER THROUGH THE DAY ON SATURDAY AS IS SLOWLY SLIDES OFF THE
CAROLINA COAST. SOME HIGH LEVEL MOISTURE IS STREAM NORTHEAST FROM
THE LOWER MS VALLEY INTO SRN NEW ENGLAND AND COULD PRODUCE SOME
BKN CIRRUS FOR RIC/PHF/SBY...BUT OTHERWISE LITTLE MORE THAN
SCATTERED CIRRUS IS EXPECTED. THE ONLY POTENTIAL RESTRICTION COULD
BE SOME GROUND FOG AT PHF AS TEMP/DEW POINT DEPRESSIONS ARE
ALREADY AT 6 DEGREES AND THE SENSOR DID REPORT A SHORT PERIOD OF
IFR FOG LAST NIGHT. MOSTLY LIKE THIS WOULD BE A SHORT TEMPORARY
CONDITION SO WILL NOT INCLUDE IN THIS TAF ISSUANCE...BUT COULD
NEED TO ADD IT FOR THE NEXT FORECAST CYCLE.

OUTLOOK...A COLD FRONT APPROACHES FROM THE NORTHWEST SATURDAY
NIGHT AND SUNDAY. THIS ALONG WITH ASSOCIATED LOW PRESSURE SYSTEM
MOVING THROUGH THE CAROLINAS WILL BRING WIDESPREAD RAIN AND
PERIODS OF IFR SUNDAY THROUGH MONDAY. THE WEATHER IMPROVES FOR
TUESDAY AND WEDNESDAY AS HIGH PRESSURE BUILDS BACK INTO THE MID
ATLANTIC STATES.

&&

.MARINE...
FAIRLY TRANQUIL CONDITIONS EXPECTED ON THE MARINE AREA THROUGH
SUNDAY...AS HIGH PRESSURE PREVAILS OVER OR JUST EAST OF THE AREA.
WINDS OVER THE WEEKEND EXPECTED TO GENERALLY BE 10 KTS OR LESS...
WITH SEAS 2 FEET OR LESS AND WAVES 1 TO 2 FEET ON THE BAY. NEXT
FRONTAL SYSTEM APPROACHES THE AREA LATE SUNDAY...AND CROSSES THE
AREA ON MONDAY. THIS FRONT WILL BRING A WIND SHIFT TO THE
NORTH...ALTHOUGH ALL MODELS SUGGEST THE SURGE WILL REMAIN BELOW
SCA CRITERIA. HOWEVER...WIND SPEEDS IN THE 10 TO 15 KT RANGE WILL
MAKE FOR CHOPPY CONDITIONS ON BOTH THE BAY AND OCEAN FROM LATER
SUNDAY NIGHT THROUGH TUESDAY.

&&

.EQUIPMENT...
KDOX 88D RADAR IS EXPECTED TO BE OUT OF SERVICE THROUGH AT LEAST
WED 12/31. SEE FTMDOX (FREE TEXT MESSAGE) FOR DETAILS.

&&

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

&&

$$
SYNOPSIS...MAM
NEAR TERM...BMD/MAM
SHORT TERM...AJZ/MAM
LONG TERM...WRS
AVIATION...ESS
MARINE...WRS
EQUIPMENT...AKQ







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