AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
AFDLWX 915 PM EST MON JAN 5 2003
WATER VAPOR LOOP SHOWS A BROAD TROUGH DOMINATING THE CENTRAL
CONUS...WITH A CUTOFF LOW OVER BAJA CALIFORNIA SHEARING NORTHEAST
INTO THE UPSTREAM PORTION OF THE TROUGH AXIS. 21Z SURFACE ANALYSIS
PLACES A 1007MB LOW OVER UPSTATE NEW YORK...WITH AN OCCLUDED FRONT
SOUTH INTO LOWER SOUTHERN MARYLAND. A WARM/STATIONARY BOUNDARY
EXTENDED EAST INTO THE ATLANTIC FROM LOWER MARYLAND...WHILE A COLD
FRONT WAS ANALYZED FROM LOWER SOUTHERN MARYLAND DOWN THE LEE OF THE
APPALACHIANS.
IR AND 11-3.9U SATELLITE BOTH INDICATE UPPER LEVEL MOISTURE WILL
GRADUALLY CLEAR THE SOUTHEASTERN FORECAST AREA THROUGH MIDNIGHT.
STRONG DOWNSLOPE WIND COMPONENT WHEN COMBINED WITH RAPIDLY
INCREASING ANTICYCLONIC LOW LEVEL FLOW...HAS DIMINISHED LOW LEVEL
CLOUDINESS EAST OF THE MOUNTAINS. THUS...A MORE OPTIMISTIC BECOMING
MOSTLY CLEAR OR CLEAR WORDING WILL BE USED IN MANY LOCATIONS.
LINGERING MOISTURE FROM UPSLOPE FLOW ON THE WESTERN RIDGES WILL LEAD
TO A SLOWER CLEARING ACROSS THE MOUNTAINS. EXPECT ANY SNOW SHOWERS
TO WRAP UP ALONG THE ALLEGANY FRONT WITH ANTICYCLONIC FLOW
INCREASING. IN ADDITION...WINDS ARE FORECAST TO BACK FROM NORTHWEST
TO WEST IN RESPONSE TO THE BUILDING HIGH PRESSURE...WHICH WILL
PRECLUDE LAKE EFFECT MOISTURE FROM MAKING AN IMPACT THIS FAR SOUTH
LATER OVERNIGHT.
IAD AND ACARS SOUNDINGS SHOW MIXING UP TO 3KFT THIS EVENING AS COLD
ADVECTION HAS STEEPENED LOW LEVEL LAPSE RATES...WHILE PRESSURE RISES
OF 3MB HAVE BEEN NOTED BETWEEN 21Z-00Z. WINDS OF 35-40KT HAVE BEEN
MEASURED AT 3KFT ON SOUNDINGS/VAD WIND PROFILE. THIS WILL ALLOW
NORTHWEST WIND GUSTS OF 25-30 MPH TO CONTINUE DURING THE LATE
EVENING...BEFORE THE NOCTURNAL INVERSION FORMS CUTTING OFF FLOW
ALOFT AS SHOWN BY 18Z ETA BUFKIT FORECAST SOUNDINGS. EXPECT
SUSTAINED WINDS AROUND 15 OR 20MPH GIVEN TIGHT PRESSURE GRADIENT.
CURRENT TEMPERATURE FORECAST LOOKS REASONABLE GIVEN CURRENT
OBSERVATIONS...SUSTAINED NORTHWEST WINDS OVERNIGHT...AND MOS
FORECASTS. WILL HOWEVER OPEN UP THE RANGE ACROSS HIGHLAND/PENDLETON
COUNTIES.
GRIDS ARE IN GOOD SHAPE...THEREFORE NO UPDATE TO GRIDS/AFM/PFM
PLANNED. UPDATED ZFP/EOL HAVE BEEN SENT.
.AVIATION: EXPECT GENERALLY 33012G20KT TO SLACKEN TO 33012KT AS
NOCTURNAL INVERSION GRADUALLY FORMS DURING THE MIDDLE PORTION OF THE
NIGHT. NO VISIBILITY/SKY/PRECIPITATION CONCERNS OVERNIGHT. EXPECT
WINDS TO GUST AGAIN FROM THE NORTHWEST TO 25-30KT BEGINNING IN THE
MID MORNING.
.MARINE: WILL KEEP SMALL CRAFT ADVISORY GOING AS GUSTY NORTHWEST
WINDS FORECAST WILL BEGIN ACROSS THE WATERS SHORTLY WITH TIGHTENING
GRADIENT AND ARRIVAL OF PRESSURE RISES. THIS LOOKS LIKE THE STATUS
QUO DURING THE NEXT SEVERAL DAYS AS STRONG HIGH PRESSURE BEGINS TO
BUILD ACROSS THE REGION FROM THE PLAINS.
UPDATED CWF HAS BEEN SENT.
ROGOWSKI
.LWX...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SCA ANZ530>537...ALL ZNS.
$$