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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 131126
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
626 AM EST FRI DEC 13 2013

.SYNOPSIS...
HIGH PRESSURE MOVES OFF THE MID ATLANTIC COAST TODAY. LOW PRESSURE
FROM THE SOUTHWEST TRACKS ACROSS THE REGION SATURDAY AND SATURDAY
NIGHT. HIGH PRESSURE BUILDS BACK INTO THE AREA SUNDAY THROUGH THE
MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SFC HIGH MOVES ACROSS THE REGION THIS MORNING THEN SHIFTS OFFSHORE
BY LATE AFTERNOON. AFTER A COLD START...RETURN SW FLOW ALLOWS H85
TEMPS TO SLOWLY WARM. PLENTY OF SUN TO START THE DAY WITH TSCTNS
SHOWING SOME HIGH LEVEL CLOUDS BEGINNING TO OVERSPREAD THE AREA FROM
THE WEST BY LATE AFTERNOON. HIGHS M-U40S EXCEPT L40S ERN SHORE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
CANADIAN HIGH PRESSURE DROPS SOUTHEAST INTO ERN CANADA TONIGHT AND
SATURDAY. MEANWHILE...SOUTHERN STREAM JET BECOMES ACTIVE AS S/W
ENERGY EXITS THE SW CONUS AND SPAWNS CYCLOGENESIS ACROSS THE CENTRAL
GULF COAST STATES TONIGHT...WITH MAIN LOW PROGGED TO TRACK NE ACROSS
THE MID ATLANTIC REGION SAT INTO SAT NGT. THIS COMPLEX / MILLER B
SYSTEM BECOMES A SINGLE STORM E OF NJ SAT NIGHT...BEFORE LIFTING NE
TO OFF THE NEW ENGLAND COAST SUN AFTERNOON.

CLOUDS QUICKLY INCREASE THIS EVENING AHEAD OF THIS SYSTEM. EXPECT
THE LOWEST TEMPS ACROSS EASTERN COUNTIES WHERE SKIES STAY MSTLY
CLEAR THIS EVENING. READINGS STEADY OUT AFTER MIDNIGHT AS CLOUDS
THICKEN. LOWS U20S TO NEAR 30 E OF I95...30-32 W OF I95.

MODELS CONTINUE TO AGREE THAT THE MAIN BULK OF PCPN DOES NOT ARRIVE
ACROSS THE FA UNTIL LATE SAT MORNING AND AFTERNOON. HOWEVER...DATA
ALSO SUPPORT SOME (LIGHT) H85 WAA PCPN ACROSS NWRN MOST COUNTIES
AFTER 09Z TONIGHT. THIS LEADS TO P-TYPE ISSUES AS THE SOUNDINGS
INDICATE RATHER DRY AIR IN LOWER LEVELS AT ONSET OF THIS MOISTURE.
DESPITE MARGINAL CRITICAL THICKNESSES...THIS DRYER AIR SHUD RESULT
IN A LIGHT WINTERY PCPN MIXTURE MAINLY N&W OF A FVX-LKU LINE AS
TEMPS HOVER AROUND FREEZING. LITTLE IF ANY ACCUMS EXPECTED SO NO
ADVISORY NEEDED. QPF RATHER MINIMAL (TRACE TO A FEW HUNDREDTHS AT
BEST). WILL HIGHLIGHT THIS TIME FRAME IN HWO.

RAIN OVERSPREADS THE REGION FROM LATE SATURDAY MORNING THROUGH THE
AFTERNOON HOURS AHEAD OF THE APPROACHING LOW. SLEET MAY CONTINUE TO
MIX IN THROUGH THE LATE MORNING ESPECIALLY OVER LOUISA/FLUVANNA
COUNTIES AS INSITU WEDGE KEEPS TEMPS JUST ABOVE FREEZING. SOME SLEET
MAY MIX IN AT THE ONSET ACROSS THE LOWER MARYLAND EASTERN SHORE AS
AIRMASS THERE WILL BE DRY TO START. INDICATED RM IN GRIDS AS DECENT
LIFT PROGGED ACROSS THE AREA LATE IN THE DAY. A WIDE RANGE IN TEMPS
EXPECTED AND WILL ALL DEPEND ON THE EXACT TRACK OF THE LOW. HIGHS
RANGE FROM THE U30S EXTREME NWRN COUNTIES TO THE M-U50S SERN COASTAL
AREAS DUE TO ONSHORE FLOW AHEAD OF DEVELOPING COASTAL LOW.

PRIMARY LOW FILLS WITH THE SECONDARY COASTAL LOW BECOMING THE MAIN
LOW FEATURE SAT NIGHT THEN QUICKLY LIFTING NE OF THE AREA WHILE
DEEPENING SUNDAY MORNING. DATA CONTINUES TO SUPPORT WIDESPREAD PCPN
ACROSS FA SAT EVENING...BUT MOST 00Z MODEL RUNS SHOW A DRY SLOT
QUICKLY PUNCHING NE AND ENDING THE PCPN SW-NE AFTER MIDNIGHT. THIS
QUICKER THAN PREVIOUS MODELS...SO ADJUSTED THE GRIDS ACCORDINGLY.
TEMPS CHALLENGING AS COASTAL READINGS MAY RISE DURING THE EVENING
THEN FALL BACK AS THE LOW PASSES BY TO THE NORTH. STEADY OR SLOWLY
FALLING TEMPS BACK INTO THE 30S ONCE PCPN TAPERS OFF AFTER MIDNIGHT.
TOTAL QPF BETWEEN ONE HALF TO ONE INCH EXPECTED.

SUNDAY NOW LOOKS DRYER EXCEPT FOR SOME LINGERING RAIN ALONG COASTAL
SECTIONS DURING THE MORNING. DECREASING CLOUDINESS THROUGH THE DAY.
DOWNSLOPING W-NW WIND RESULTS IN TEMPS WARMING INTO THE M-U40S NORTH
TO L-M50S ACROSS THE SOUTH.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
DRY/TRANQUIL WX LOOKS TO BE ON TAP NEXT WEEK WITH HIGH PRESSURE IN
CONTROL THROUGHOUT MOST OF THE PERIOD. THE ONLY EXCITEMENT WILL BE
THE PASSAGE OF A DRY COLD FRONT EITHER LATE TUESDAY OR TUESDAY
NIGHT. COOL MONDAY WITH HIGHS IN THE UPR 30S TO MID 40S. MILDER
TUESDAY AHEAD OF THE FRONT WITH HIGHS IN THE 40S TO LOW 50S. NEAR TO
SLIGHTLY BELOW NORMAL WED/THURS WITH HIGHS IN THE MID 40S TO LOW
50S.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE CAROLINAS TODAY
RESULTING IN DRY/VFR CONDITIONS ACROSS THE REGION. AS HIGH
PRESSURE BUILDS TO THE SOUTH...SCT-LOCALLY BKN MID-HIGH LEVEL
CLOUDS WITH DECKS 12-16K FT AGL WILL ROUND THE NRN PERIPHERY OF
THE HIGH...IMPACTING NRN VA AND KSBY. ELSEWHERE...MODEST MID LEVEL
MOISTURE COULD PRODUCE A FEW MID LEVEL CLOUDS AOA 12K FT...BUT
WILL LEAVE SKC IN TAFS. SW SFC WINDS WILL REMAIN GENERALLY AOB 10
KT.

HIGH PRESSURE WILL SLIDE OFFSHORE TONIGHT AS A LOW PRESSURE SYSTEM
EJECTS FROM THE SRN PLAINS. RETURN FLOW WILL STREAM MOISTURE INTO
THE REGION IN ADVANCE OF THE LOW WITH CLOUDS THICKENING AND
LOWERING THRU LATE TONIGHT. PRECIP WILL OVERSPREAD THE REGION LATE
TONIGHT-EARLY SAT MORNING...WITH PERIODS OF RAIN DURING THE DAY
SATURDAY. FROZEN PRECIP IS POSSIBLE FOR A BRIEF PERIOD SAT MORNING
ACROSS THE ERN VA PIEDMONT...BUT CONFIDENCE REMAINS HIGH THAT TAF
SITES WILL REMAIN LIQUID. THE LOW WILL CROSS THE LOCAL AREA LATE
SAT INTO SUNDAY MORNING WITH CONDITIONS IMPROVING THRU SUNDAY
MORNING. LOWER CIGS AND VSBYS ARE LIKELY SAT DUE TO MODERATE-
LOCALLY HEAVY RAINFALL.
-- End Changed Discussion --

&&

.MARINE...
HIGH PRESSURE CONTINUES TO BUILD OVER THE SOUTHEAST STATES THIS
MORNING...NUDGING OVER THE SRN WATERS. COLD AIR OVER THE WATER AND
GRADIENT WINDS (HIGH TO THE SOUTH AND LOW PRESSURE OVER MAINE) STILL
PRODUCING GUSTS OF 15-18 KT. SEAS REMAIN 2-3 FT. GRADIENT WILL RELAX
TODAY AS THE SFC HIGH MOVES OFF THE NC COAST AND WINDS BACK TO THE
SW. ATTENTION TURNS TO A LOW PRESSURE SYSTEM EJECTING FROM THE SRN
PLAINS INTO THE DEEP SOUTH TONIGHT. HIGH PRESSURE WILL ALSO SETTLE
OVER THE ST LAWRENCE RIVER VALLEY TONIGHT-SAT. THE LOW WILL LIFT
OVER THE WATERS LATE SAT INTO SAT NIGHT. THE GRADIENT WILL
STRENGTHEN SAT MORNING AS WINDS A FEW THOUSAND FT UP INCREASE TO 30+
KT. WAA IN ADVANCE OF THE LOW WILL LIMIT THE AMOUNT OF MIXING...SO
DO NOT ANTICIPATE THE HIGHER VELOCITY SPEEDS TO MIX TO THE WATER.
WILL CAP SPEEDS AT 15 KT AND GUSTS UNDER 20 KT SAT. WHILE SCA CONDS
MAY NOT BE REACHED SAT...COMBINATION OF SW WINDS 15 KT AND PERIODS
OF RAIN AND LOW VISIBILITIES WILL MAKE BOATING DIFFICULT. AS COLDER
AIR BEGINS TO WRAP AROUND THE SYSTEM SAT NIGHT-SUN
MORNING...STRONGER WINDS WILL LIKELY BEGIN TO MIX DOWN TO THE WATER.
HOWEVER...ONLY MARGINAL SCA CONDITIONS POSSIBLE AS WEAK LAPSE RATES
PREVENT THE STRONGEST GRADIENT WINDS FROM MIXING TO THE WATER. SEAS
WILL INCREASE RAPIDLY LATE SAT-SAT NIGHT....BUILDING TO 3-6 FT
(HIGHEST 20 NM OUT). HAVE UNDERCUT WAVEWATCH SLIGHTLY AS GFS WINDS
APPEAR TOO STRONG. STRONGEST CAA OCCURS SUN-SUN NIGHT. SCA
CONDITIONS WILL BE POSSIBLE. HIGH PRESSURE RETURNS EARLY NEXT WEEK.

&&

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

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...JDM
AVIATION...SAM
MARINE...SAM