FXUS61 KAKQ 300314
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1014 PM EST SUN NOV 29 2009
.SYNOPSIS...
HIGH PRESSURE REMAINS OFF THE SOUTHEAST COAST OVERNIGHT. A COLD
FRONT WILL CROSS THE MID ATLANTIC REGION MONDAY AFTERNOON AND
NIGHT...WITH HIGH PRESSURE BUILDING BACK OVER THE AREA TUESDAY
INTO EARLY WEDNESDAY. LOW PRESSURE OVER THE CENTRAL GULF COAST
REGION EARLY WEDNESDAY...WILL STRENGTHEN AS IT TRACKS NORTHEAST
ACROSS THE APPALACHIANS WEDNESDAY NIGHT AND EARLY THURSDAY...THEN
INTO NORTHERN NEW ENGLAND BY LATE THURSDAY. HIGH PRESSURE WILL
BUILD INTO THE AREA FROM THE LOWER MISSISSIPPI VALLEY ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
HI AND MID LVL CLDS WILL CONTINUE TO INCREASE AND THICKEN FM NW
TO SE OVRNGT AHEAD OF THE COLD FRONT ADVANCING FROM THE OH VLY
INTO THE MTNS. WITH SSW WNDS CONTINUING OVRNGT UNDR A GENERALLY
PRTLY CLDY SKY...MIN TEMPS WILL RANGE FM THE UPR 40S TO LWR 50S
MOST PLACES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
MONDAY...
GFS/NAM/SREF/ECMWF MODEL CONSENSUS IS FAIRLY GOOD WITH RESPECT TO
THE COLD FRONTAL PASSAGE THROUGH THE CWA MON AFTN/EVE. FAIRLY
SIZABLE POCKET OF LOW-MID LVL FGEN FORCING (QVECTOR CONVRGNCE) ASSCD
WITH THE UPR TROUGH...AS IT BECOMES MORE NEG TILTED WITH TIME...
AIDED BY THE 120+ KT JET AT 300 MB. THE ONLY DRAWBACK FOR A
SIGNIFICANT RAIN EVENT IS THE SPEED AT WHICH THE SYSTEM TRAVERSES
THE REGION. THE UPSHOT: HAVE BOOSTED POPS IN ALL AREAS (ESP BY
AFTN...THEN EVENG OVER ERN AREAS). GIVEN THE RELATIVELY FAST
PROGRESSION OF THIS SYSTEM...FOR MOST AREAS HAVE FCST QPF VALUES
CLOSE TO HPC GUIDANCE (I.E. BTWN 0.1 TO 0.25")...THOUGH GIVEN THE
AMPLIFICATION OF THE UPR TROUGH WITH TIME WOULD NOT BE SURPRISED TO
SEE HIGHER AMOUNTS (I.E. CLOSER TO A HALF INCH) E OF I-95.
MAX TEMPS ON MON RANGING FM THE MID 50S IN THE NW TO MID/UPR 60S SE.
ACCELERATED CLEARING ON MONDAY NIGHT CONSIDERING STRONG DOWNSLOPE
FLOW BEHIND THE SYSTEM. LOWS GENERALLY IN THE MID 30S NW HALF OF
FCST AREA TO AROUND 40/LWR 40S OVER SE.
TUESDAY...
CLEARING CONTINUES ON TUESDAY AS HIGH PRES SPILLS OVER THE AREA
FROM THE SW AND UPPER FLOW FLATTENS OUT AND BECOMES QUASI ZONAL BY
LTR TUE/ERY WED. THIS SHUD TRANSLATE TO MOSTLY SNY SKIES...AND MAX
TEMPS IN THE M/U50S (XCPT LWR TO MID 50S OVER THE EASTERN SHORE).
INCRSNG WAA MID/HIGH CLOUDINESS AHEAD OF THE NEXT SYSTEM BY LATE TUE
NIGHT...WHICH SHOULD KEEP TEMPS FROM DROPPING BELOW THE MID/UPR 30S
(THOUGH COLDER OVER LWR MD ERN SHORE (ARND 30)...CLOSER TO DEPARTING
SFC HIGH WHERE SKIES SHOULD REMAIN MSTLY CLEAR FOR A LONGER PERIOD).
WEDNESDAY...
DEEPENING SRN STREAM SYSTEM OVER CENTRAL GULF REGION EARLY WILL
LIFT...STAYING WELL INLAND...ACROSS OR NEAR THE SPINE OF THE
APPALACHIANS BY WED NIGHT. THIS IS A FAIRLY ANOMALOUS TRACK...
I.E. 1) ACROSS OR NEAR THE MNTNS...2) SO FAR INLAND FROM THE
COAST...AND OBVIOUSLY WILL BE DETERMINED BY THE EVOLUTION
(AMPLIFICATION) OF THE UPR LVL SYSTEM. FOR OUR REGION...IT STILL
APPEARS AS IF THE BEST RAIN CHANCES (HIGHER QPF) WILL BE WED NIGHT
AND ON THU (SEE LONG TERM DISCUSSION BELOW)...SO THE MAIN CONCERN
ON WED WILL BE WITH TIMING THE POPS INTO OUR REGION FROM THE S/SW.
GIVEN THE MODEL TRENDS (TOWARD A MORE AMPLIFIED UPR TROUGH)...THE
GFS STILL APPEARS TOO FAST WITH THE NE/E EXPANSION OF DEEPER MOIST
ISENTROPIC ASCENT ON WED...AND AS SUCH HAVE BASICALLY FOLLOWED
MORE CLOSELY TO THE SREF...WHICH IS ESSENTIALLY A BLEND BTWN THE
NAM (SLOWEST MODEL) AND ECMWF (FASTER MODEL...THOUGH STILL NOT AS
FAST AS GFS).
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
PRECIP WILL CONTINUE TO SPREAD FURTHER INTO THE RGN WED EVE AND
SHOULD BE FAIRLY LIGHT (ESP FAR NE) SW TO NE INTO WED NIGHT. BULK OF
PRECIP LOOKS TO OCCUR DURING THE OVRNT HRS AND INTO THU AM BEFORE
TAPERING OFF LATE DAY. OVERALL THE SYSTEM SHOULD BRING A DECENT
RAINFALL TO MOST OF THE RGN WITH AMOUNTS IN GENERAL RANGING FROM 1-3
INCHES (W/LOCALLY HIGHER/LOWER AMTS POSSIBLE). SYSTEM CONTINUES TO
SHOW SIGNS OF BECOMING MORE STAGNANT THUS LEADING TO A SLOWER EAST
PROGRESSION AS THE H50 FLOW CONTINUES TO TIGHTEN/INTENSIFY AT MID
LVLS. OVER THE COURSE OF THE PAST FEW DAYS PRECIP AMNTS HAVE
CONTINUED TO INCREASE WITH THIS SYSTEM WITH GUIDANCE...NOT ONLY OVER
THE GULF BUT ALSO INTO THE MID ATL RGN. STILL THINKING SOME PORTIONS
OF THE AREA MAY SEE A HIGHER RANGE OF QPF...POSSIBLY ON THE ORDER OF
3-5 INCHES OF RAINFALL.
AS SYSTEM MOVES FURTHER TO THE NE LOOK FOR SOME OF THE NRN STREAM
FLOW AND COOLER AIR ALOFT TO BE PHASED INTO THE MID LVL FLOW OVER
THE MID ATL RGN LATE WK AND INTO THE WKND BEHIND SYSTEM...WHICH WILL
MAKE FOR BLO NRML TEMPS.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
SCT-BKN HIGH CLOUDS COVER THE TAF SITES THIS EVNG. SW WINDS WILL
CONTINUE AROUND 5-10 KTS OVERNIGHT WITH 92H WINDS INCREASING TO
30-35 KTS BY AROUND MIDNIGHT. WENT CLOSE TO LAV WINDS WHICH INDICATE
GUSTY WINDS AT ORF PHF AND ECG BY MIDDAY MON. THESE WINDS WILL BE
JUST AHEAD OF AN AREA OF SHOWERS ASSOCIATED WITH A COLD FRONT. MET
MOS INDICATES IFR CONDITIONS AT MOST OF THE TAF SITES DURING THE
PCPN EVENT BUT WITH A WESTERLY COMPONENT TO THE WIND...CONFIDENCE
IS LOW FOR THESE CONDITIONS TO OCCUR.
BEYOND THE TAF PERIOD...SHOWERS WILL MOVE QUICKLY OFFSHORE AND WINDS
TURN TO THE W/NW WHICH WILL PROMOTE VFR CONDITIONS. DEW POINTS DROP
SHARPLY MON NIGHT WHICH SHOULD PREVENT FOG FORMATION TUE MRNG.
HIGH PRESSURE OVER THE SOUTHEAST STATES WILL CONTINUE THE VFR
CONDITIONS THROUGH WED. LOW PRESSURE FROM THE GULF COAST REGION WILL
MOVE ON A NORTHEASTWARD TRACK TO THE WEST OF OUR AREA BUT WILL BRING
PLENTY OF MOISTURE TO EASTERN VIRGINIA. LOOK FOR WIDESPREAD PCPN AND
AREAS OF IFR WED NIGHT AND THU. A COLD FRONT WILL MOVE THROUGH LATE
THU AND BRING IMPROVING CONDITIONS THU NIGHT...CONTINUING INTO FRI.
&&
.MARINE...
SW WINDS WILL PICK UP LATER TONIGHT IN ADVANCE OF A FRONTAL SYSTEM
APPROACHING THE REGION FROM THE NW. HAVE HOISTED FLAGS OVER THE BAY
AND CSTL WATERS TNT (RATHER MARGINAL BUT W/COLAB FROM OTHER OFFICES)
LEFT OUT CRT SND ATTM. WINDS WILL LIKELY DROP FOR A SHORT TIME
(POSSIBLY UNDER SCA CRITERIA) TMRW AFTN BEFORE INCREASING ONCE AGAIN
ALONG AND BEHIND FRONTAL PASSAGE AS A GOOD CAA PUSH DVLPS OVER THE
WATERS BEFORE SUBSIDING TUE AM. HIGH PRES RETURNS FOR A SHORT TIME
BEFORE LOW PRES SYSTEM APPROACHES FROM THE SW. WINDS WILL INCREASE
OUT OF THE SE TO S WED NIGHT/ERLY THU AS SFC LOW MOVES SW/NE OVER
LAND. WINDS SHIFT TO THE W/NW LATE THU BEFORE HIGH PRES MOVES BACK
OVER THE RGN BY THE WKND.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR ANZ630>632-650-
652-654-656-658.
SMALL CRAFT ADVISORY FROM 1 PM MONDAY TO 7 AM EST TUESDAY FOR
ANZ633.
&&
$$
SYNOPSIS...BKH
NEAR TERM...BKH/TMG
SHORT TERM...BKH
LONG TERM...CCW
AVIATION...LSA
MARINE...CCW/LSA
