000
FXUS61 KLWX 060904
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
404 AM EST TUE JAN 6 2009
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE TENNESSEE VALLEY NORTH INTO THE
GREAT LAKES THROUGH WEDNESDAY. A SURGE OF MOISTURE WILL MOVE INTO
THE MID ATLANTIC AHEAD OF THE STORM. SOME WINTRY PRECIPITATION IS
EXPECTED TODAY INTO TONIGHT BEFORE PRECIPITATION CHANGES TO RAIN
BEFORE ENDING WEDNESDAY.
COLDER AIR WILL PUSH INTO THE REGION FOR THURSDAY AND FRIDAY. A
WARM FRONT WILL LIFT NORTH OF THE REGION FRIDAY NIGHT...FOLLOWED
QUICKLY BY A COLD FRONT SATURDAY. COLD AIR WILL LAST INTO NEXT
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
ONE LEADING AREA OR EAST/WEST ORIENTED BAND OF PRECIPITATION HAS
DEVELOPED ACROSS THE CWA EARLY THIS MORNING...RESPONSIBLE FOR MAINLY
A RAIN/SLEET MIX ACROSS THE CWA...ALTHOUGH CANT RULE OUT A FEW
SNOWFLAKES ON THE NORTHERN FRINGE OF THE PRECIPITATION AREA EITHER.
FURTHER SOUTH...RADAR IMAGERY SHOWS THAT THERES A LOT MORE MOISTURE
LURKING OFF TO THE SOUTH WHICH WILL SPREAD NORTH TODAY.
REGARDING THE EVENT TODAY AND TONIGHT...ONE THING IS FOR
SURE...THERE/S A DECENT AMOUNT OF QPF TO WORK WITH TODAY AND
TONIGHT. OBVIOUSLY...HOW MUCH OF WHAT PRECIPITATION TYPE FALLS IS
DEPENDENT ON BOUNDARY LAYER AND SURFACE TEMPERATURES DURING THE
EVENT. FOR THE MOST PART...THE COLD AIR IS MARGINAL...AND WILL BE
COLDEST FOR THE LONGEST ACROSS WESTERN MARYLAND AND EASTERN WEST
VIRGINIA PANHANDLE. WE PREFER THE GFS SOLUTION OVER THE NAM FOR ITS
THERMAL PROFILES.
PRECIPITATION THIS MORNING WILL MAINLY RAIN OR SLEET...BUT THE
COLUMN IS UNDERGOING A COOLING PROCESS...AND WET BULBING WILL LEAD
TO MORE OF THE LATER THAN THE FORMER CLOSE TO DAYBREAK. CONSIDERING
SFC-925 MB TEMPERATURES...FREEZING RAIN WILL LIKELY BECOME MORE
APPARENT ACROSS THE HIGHLANDS/CENTRAL SHENANDOAH VALLEY LATER THIS
MORNING AND EXPAND NORTH THROUGH THE AFTERNOON AS SFC TEMPERATURES
WILL FALL A LITTLE BEFORE LEVELLING OUT LATER IN THE DAY. THE
BIGGEST FREEZING RAIN IMPACT IS GOING TO BE ACROSS ELEVATIONS
GREATER THAN 1000 FEET. WITH COLD AIR ERODING THE SLOWEST ACROSS
WESTERN MARYLAND AND THE EASTERN WEST VIRGINIA PANHANDLE...THESE
AREAS HAVE THE GREATEST POTENTIAL TO ACCRETE A QUARTER INCH OR MORE
OF ICE AND WILL BE UNDER A WINTER STORM WARNING. THE WARNING MAY
NEED TO BE EXPANDED A TIER EAST INTO JEFFERSON...CLARK AND FREDERICK
MD COUNTIES BUT DID NOT HAVE AS GREAT OF CONFIDENCE FOR A QUARTER
INCH OR MORE IN THESE AREAS. OUTSIDE OF THE WARNING AREA...SOME
FREEZING RAIN IS STILL EXPECTED FURTHER SOUTH IN THE SHENANDOAH
VALLEY AND POTOMAC HIGHLANDS AND ACROSS THE NORTHWEST SUBURBS AND
WASHINGTON AND BALTIMORE BUT AMOUNTS OF ARE EXPECTED TO BE BELOW
WARNING CRITERIA AND AGAIN THE MAIN IMPACT WILL BE ELEVATIONS ABOVE
1000 FEET. WILL DROP FAIRFAX AND PRINCE WILLIAM FROM THE ADVISORY AS
FREEZING RAIN IS NO LONGER EXPECTED. THESE COUNTIES...LIKE THE
DISTRICT...BALTIMORE CITY AND CENTRAL MARYLAND WILL HAVE A
RAIN/SLEET MIX TODAY...WITH JUST RAIN ACROSS LOWER SOUTHERN
MARYLAND.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
LOW PRESSURE SYSTEM WILL TRACK ACROSS THE EASTERN
GREAT LAKES REGION WED WITH A TRAILING COLD FRONT PUSHING THRU THE
AREA FROM W TO E WED AFTERNOON/EVENING. RA WILL CONTINUE WED ACROSS
THE CWA...HOWEVER ENOUGH COLD AIR SHOULD REMAIN IN PLACE ACROSS
WESTERN MD FOR POCKETS OF ZR THRU MID MORNING WED. STRONG CAA
ACCOMPANIES FROPA LATE WED INTO THU. ANY LINGERING RA SHOULD MIX AND
CHANGE TO SNOW WEST OF THE METROPOLITAN CORRIDOR LATER WED BEFORE
ENDING WED NIGHT. WNW FLOW AT LOWER LEVELS AND STRONG CAA WILL LEAD
TO UPSLOPE SNOW SHOWERS AND WINDY CONDITIONS ACROSS HIGHER
ELEVATIONS IN THE FAR WESTERN ZONES WED NIGHT INTO THU.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
DRY AND COLD CONDITIONS ARE EXPECTED FRI AS HIPRES BUILDS INTO THE
AREA. THE NEXT COLD FRONT WILL APPROACH ON SAT. THERE LOOKS TO BE
LIMITED MOISTURE ACCOMPANYING THE FRONT AND THE LATEST 00Z GFS/ECMWF
BOTH SHOW MOISTURE NOT MAKING IT ACROSS THE MOUNTAINS. THEREFORE
LOWERED POPS SAT. VERY COLD AIR WILL FILTER IN BEHIND THE COLD FRONT
SUN INTO EARLY NEXT WEEK. HAVE LOWERED MAX TEMPS DURING THIS TIME TO
BE MORE IN LINE WITH THE LATEST GUIDANCE.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
MVFR CONDITIONS DEGRADE INTO THE IFR CATEGORY LATER THIS MORNING AND
WILL LIKELY PERSIST THROUGH AT LEAST 12Z WEDNESDAY. PRECIPITATION
TYPE WAS A CHALLENGE...AND DEPENDS ON THE EXACT TERMINAL. THE MAIN
THEME WILL BE FOR ANY WINTRY PRECIPITATION TODAY TO CHANGE OVER THE
PLAIN RAIN TONIGHT.
MVFR/IFR CONDITIONS EXPECTED WED MORNING...BEFORE
IMPROVING CONDITIONS LATER WED AS A COLD FRONT MOVES THRU THE
REGION. BEHIND THE FRONT...GUSTY WNW WINDS EXPECTED INTO FRI. HIPRES
WILL SETTLE INTO THE AREA FRI BEFORE THE NEXT COLD FRONT WILL IMPACT
THE TERMINALS SAT.
&&
.MARINE...
NORTHEAST WINDS WILL PREVAIL THROUGH TONIGHT...AND WILL START TO
INCREASE LATER AT NIGHT ALTHOUGH WE SHOULD REMAIN BELOW SMALL CRAFT
ADVISORY THRESHOLDS. RAIN AND SLEET MIXED TODAY WILL CHANGE OVER TO
PLAIN RAIN TONIGHT...WITH VSBY RESTRICTIONS OF 1 TO 3 NM POSSIBLE.
A COLD FRONT WILL TRACK THRU THE WATERS LATER WED...BRINGING
GUSTY STARTING WED MORNING. A SMALL CRAFT ADV HAS BEEN ISSUED FOR
THE WATERS WED MORNING THRU THU AFTERNOON. THE SMALL CRAFT ADV MAY
NEED TO BE EXTENDED INTO FRI AFTERNOON AS GUSTY WINDS ARE EXPECTED
TO CONTINUE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL 9 AM EST WEDNESDAY FOR
MDZ004>007-009-010.
WINTER STORM WARNING UNTIL 9 AM EST WEDNESDAY FOR MDZ003-501-
502.
VA...WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR
VAZ021-025-026-036>038.
WINTER WEATHER ADVISORY UNTIL 9 AM EST WEDNESDAY FOR
VAZ029>031-039>042-051.
WINTER STORM WARNING UNTIL 9 AM EST WEDNESDAY FOR VAZ027-028.
WV...WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR
WVZ054.
WINTER WEATHER ADVISORY UNTIL 9 AM EST WEDNESDAY FOR WVZ053-
501-502.
WINTER STORM WARNING UNTIL 9 AM EST WEDNESDAY FOR WVZ050>052-
055-503-504.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM WEDNESDAY TO 6 PM EST THURSDAY
FOR ANZ530>537.
&&
$$
SYNOPSIS...PELOQUIN
NEAR TERM...PELOQUIN
SHORT TERM...JRK
LONG TERM...JRK
AVIATION...JRK/PELOQUIN
MARINE...JRK/PELOQUIN
