FXUS61 KAKQ 270116
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
816 PM EST THU NOV 26 2009

.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT...AS AN UPPER LEVEL
LOW PRESSURE SYSTEM MOVES ACROSS THE MID ATLANTIC STATES ON
FRIDAY. HIGH PRESSURE WILL THEN BUILD INTO THE AREA FRIDAY NIGHT
AND SATURDAY...THEN MOVES OFF THE SOUTHEAST COAST ON SUNDAY. A
COLD FRONT APPROACHES FROM THE WEST ON MONDAY...THEN MOVES OFF THE
COAST MONDAY NIGHT. HIGH PRESSURE REBUILDS INTO THE AREA ON TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
LATEST STLT IR/WV LOOPS SHOW MID/UPR LOW SPINNING ACROSS LK HURON
AND ERN LWR MI. RESIDUAL LLVL AIRMASS (MOISTURE) OVER MID ATLC
REGION HAS BEEN TOUGH TO DISLODGE THUS FAR GIVEN THE LACK OF
MIXING...BOTH HORIZONTALLY (LIGHT NE FLOW) AND VERTICALLY (LOW
LATE NOV SUN ANGLE). 

UPR TROUGH TO BECOME MORE NEGATIVELY TILTED OVERNIGHT AS IT PIVOTS
INTO THE ERN SEABOARD. WILL CONTINUE WITH SHOWERS ACROSS WRN
COUNTIES BEGINNING THIS EVENING...AS THE UPR TROUGH DROPS INTO
THE MID ATLC REGION. QG FORCING IS FAIRLY IMPRESSIVE...AT LEAST
COMPARED TO WHAT HAD BEEN EXPECTED A DAY OR SO AGO...AS IT APPEARS
FROM ALL THE SHORT TERM MODELS THE MID LVL VORT WILL DROP A BIT
FARTHER S THAN PREVIOUS EXPECTATIONS. THIS IN TURN WILL BOOST THE
DPVA FORCING ACROSS THE FCST AREA...WHILE ALSO STEEPEN MID LEVEL
LAPSE RATES (7-8C BTWN 700-500 MB)...WHICH WILL LEAD TO SCATTERED
SHOWERS...ESPECIALLY FROM LATE THIS EVENING THROUGH EARLY FRI.

AS FOR PCPN TYPE...PARTIAL THICKNESS SUPPORT RAIN THROUGH THE
MAJORITY OF THIS EVENT. HOWEVER...BY EARLY FRI AM...AS 1000-850 MB
THICKNESSES DROP TO NEAR 1305/1310 M OVER WRN AREAS...AND WITH
THE CAA (STEEPENING LAPSE RATES) ALOFT AND THUS CONVECTIVE NATURE
OF THE PCPN...CANNOT RULE OUT A CHANCE THAT THE SHOWERS WILL END
AS A PERIOD OF WET SNOW OR MIXED RAIN/SNOW W OF I-95. CERTAINLY
NOT EXPECTING A BIG DEAL OTHER THAN PERHAPS THE FIRST FEW
SNOWFLAKES OF THE SEASON.

THIS SYSTEM WILL ALSO INVIGORATE LLVL MIXING (FOR A CHANGE)
TONIGHT... WHICH WILL PUT AN END TO THE FOG/LLVL STRATUS THAT
WAS STILL PLAUGING PTNS OF THE AREA DURING THE AFTN. LOWS MID-UPR
30S W/NW PTNS TO LWR 40S E/SE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
ONCE THE COLD FRONT EXITS THE COAST EARLY FRIDAY MORNING...THE
COLD AIR WILL HELP TIGHTEN THE THERMAL GRADIENT WHICH WILL HELP
INVIGORATE THE AREA OF LOW PRESSURE THAT IS LIFTING NE ALONG THE
COAST. THIS LOW WILL INTENSIFY OFF THE NEW ENGLAND COAST. THIS
WILL HELP THE NW FLOW TO STRENGTHEN. THIS WILL LEAD TO A CLEARING
PATTERN WITH THE DOWNSLOPE FLOW AND ALSO ALLOW FOR GOOD MIXING IN
THE COLD ADVECTION. WILL KEEP MINIMAL (20-30%) CHANCES OVER THE
LWR ERN SHORE ON FRI (HIGHEST OVER LWR MD ERN SHORE)...GIVEN THE
CLOSER PROXIMITY TO THE UPR LOW AND LESS DOWNSLOPE DRYING EFFECTS
TYPICALLY SEEN IN THIS REGION WITH NW/WNW FLOW.

EXPECT TO SEE GUSTY CONDITIONS ON FRIDAY...WHILE LOCAL 1000-850
MB LLVL THICKNESS SCHEME SUPPORTS MAX TEMPS ONLY AROUND 50 TO THE
LWR 50S WITH FULL SUN. BECAUSE OF MORE CLOUDS/HIGHER PCPN
CHANCES...HAVE CAPPED HIGHS ONLY IN THE UPR 40S OVER LWR MD ERN
SHORE...50 TO 54 ELSEWHERE.

THE STRONG LOW AND UPPER TROUGH SLIDE OFF THE COAST FRIDAY
NIGHT...WHICH ALLOW THE FLOW TO WEAKEN...BUT IT WILL STILL BE COLD
WITH SOME LOCATIONS GOING BELOW FREEZING OVER CENTRAL VA. AS
RIDGING BUILD EAST ALOFT...WILL SEE A WARM ADVECTION PATTERN
DEVELOP SO TEMPERATURES WILL BEGIN TO MODERATE AND WITH VERY DRY
AIR AROUND...EXPECT SUNNY CONDITIONS WITH LIGHT WINDS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
FRONTAL BOUNDARY DRAPED ACROSS THE GRT LKS INTO THE SRN PLAINS WILL 
SLOWLY TREK TWRD THE RGN ON MON AS A LOW PRES SYSTEM RIDES ALONG IT.
HIGH CLOUDS WILL INCREASE SUN NIGHT BEFORE FRONTAL SYSTEM AND ASSCD 
LOW PRES SYSTEM MOVES OVER THE RGN MON AFTN/EVE. LOOK FOR SHRA 
ACTIVITY TO CONTINUE INTO ERLY TUE BEFORE HIGH PRES STARTS TO BUILD 
BACK INTO THE RGN. STRONG UPR LVL SYSTEM DVLPS OVER THE SRN CALIF ON 
SAT AND DIGS FURTHER OVER NRN MEXICO/SRN TX INTO MON. SYSTEM PUSHES 
INTO THE GULF COAST TUE/WED AND QUICKLY MOVES TWRDS THE RGN ON THU 
AS SRN STREAM FLOW STARTS TO FLATTEN. GFS ONCE AGAIN TRIES TO DVLP A 
COASTAL SYSTEM...BUT OTHER GUIDANCE HINTING AT MORE OF A SUPRESSED
AND WEAKER SYSTEM FURTHER SOUTH (WHICH WOULD BE MORE SUPPORTIVE
OF A FLATTER FLOW). FOR NOW WILL GO WITH BULK OF GUIDANCE.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
MAINLY VFR CONDS CONTINUE THIS EVNG. THE LONE EXCEPTION IS PHF AS
ONSHORE FLOW IS BRINGING IN SOME MARINE STRATUS LEADING TO LOWER
CIGS. EXPECT THIS TO CONTINUE FOR A COUPLE HOURS MORE BEFORE WNDS
SHIFT TO THE NW AS A COLD FNT PUSHES THROUGH THE AREA. THE COLD
FNT MVS OFFSHORE EARLY FRI MRNG AS A CSTL LOW MVS NE OFF THE
CAROLINA CST. EXPECT MAINLY VFR CONDS TO CONTINUE OVERNIGHT. SCTD
SHWRS ALONG THE FNTL BNDRY SHOULD REACH RIC BY 02Z THEN GRADUALLY PUSH
EWD. AN UPR LVL TROF CURRENTLY OVER THE OHIO VLY WL HELP SHWRS
BEHIND THE FNT TO CONTINUE THROUGH FRI MRNG.

MAIN OPERATIONAL CONCERN REMAINS GUSTY WNDS LATE TONIGHT AND FRI AS
THE COLD FNT CROSSES THE REGION. LIGHT NE TO E AHEAD OF THE FNT
WL BECOME W/NW AND INCREASE TO AROUND 10 TO 15 KTS SUSTAINED BY
SUNRISE. THE PRESSURE GRADIENT BETWEEN CSTL LOW AND AN APPROACHING
SFC RIDGE TO THE S WL ALLOW FOR BREEZY TO WINDY CONDS FRI
AFTN...WITH GUSTS TO 20-30KT POSSIBLE DURING THIS PERIOD.
OTW...LOOK FOR MAINLY VFR CONDS BY LATE AM/ERLY PM FRI AND THROUGH
THE WEEKEND. NEXT CHC OF PCPN LOOKS TO BE LATE MON INTO TUE.

&&

.MARINE...
CONTINUE WITH TIMING OF SCA TONIGHT OVER ALL WATERS AS FRONTAL 
BOUNDARY PUSHES TWRDS THE RGN. LOOK FOR WINDS TO INCREASE TONIGHT AS 
FRONT PUSHES OVER THE RGN (AFTER MIDNIGHT). COULD SEE SOME GUSTS TO 
NEAR GALE OVER THE BAY AS FRONT MOVES OVERHEAD...BUT THINK THIS WILL 
BE FOR ONLY A FEW HRS UNTIL MORE SUSTAINED GUSTS OCCUR LATER ON FRI.
AS WINDS SHIFT TO THE WNW...LOOK FOR GALE GUSTS TO START TO OCCUR 
OVER THE BAY FRI AFTN AND CONTINUE INTO SAT AM BEFORE GRADIENT 
RELAXES. 

HAVE HOISTED GALES OVER THE COASTAL ZONES AND CRT SND FRI AM THRU 
ERLY SAT. ALTHOUGH GUSTS MAY BE BELOW GALES FOR A TIME FRI AM ALONG 
THE COAST/CRT SND...WINDS SHOULD INCREASE W/IN 4 HRS AFTER INITIAL 
PASSAGE OF FRONT.

GRADIENT RELAXES VERY SLOWLY SATURDAY...AND SCA FOR SEAS WL LIKELY 
BE NEEDED OVER THE COASTAL WATERS INTO LTR SAT AT LEAST. CONDITIONS 
LOOK TO BECOME A BIT MORE BENIGN FOR SUNDAY INTO MONDAY AS FLOW 
LOOKS TO TURN SSW AS HIGH PRESSURE OVER THE SOUTHEAST CONUS BUILDS 
SOUTH OF THE REGION. ANOTHER FRONT APPROACHES FROM THE WEST BY LTR
MONDAY/TUESDAY.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST FRIDAY FOR ANZ630>632.
     GALE WARNING FROM NOON FRIDAY TO 5 AM EST SATURDAY FOR 
     ANZ630>632.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ633-650-652-
     654-656-658.
     GALE WARNING FROM 6 AM FRIDAY TO 5 AM EST SATURDAY FOR ANZ633-
     650-652-654-656-658.

&&

$$
SYNOPSIS...BKH
NEAR TERM...BKH/SMF
SHORT TERM...BKH
LONG TERM...CCW
AVIATION...AM
MARINE...CCW