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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
245 PM EST SUN DEC 21 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH TONIGHT. LOW
PRESSURE WILL TRACK UP THE MID-ATLANTIC COAST MONDAY AND TUESDAY.
A STRONG COLD FRONT WILL APPROACH THE AREA WEDNESDAY BEFORE
PASSING THROUGH WEDNESDAY NIGHT. HIGH PRESSURE WILL BUILD OVERHEAD
LATE IN THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
HIGH PRESSURE REMAINS OVER THE REGION THIS AFTERNOON AND
SUBSIDENCE BEHIND A SHORTWAVE HAS ALLOWED FOR SUNSHINE. HIGH
PRESSURE WILL BECOME CENTERED OVER NEW ENGLAND TONIGHT AND THE
SURFACE RIDGE AXIS WILL DROP SOUTHWEST THROUGH OUR REGION DURING
THIS TIME. 

POTENT LOW PRESSURE WILL TRACK THROUGH THE PLAINS TONIGHT THROUGH
MONDAY. A WARM FRONT WILL EXTEND SOUTHEAST FROM THIS SYSTEM
THROUGH THE TENNESSEE VALLEY INTO THE APPALACHIANS WHERE IT WILL
BECOME A STATIONARY FRONT THAT CONTINUES TO EXTEND THROUGH THE
SOUTHEASTERN CONUS. LOW PRESSURE WILL DEVELOP ALONG THIS BOUNDARY
OFF THE SOUTHEAST COAST TONIGHT AND IT IS EXPECTED TO TRACK UP THE
MID-ATLANTIC COAST MONDAY. THIS SYSTEM WILL BE WEAK AND MOST OF
THE DYNAMICS WILL REMAIN WELL TO OUR WEST...CLOSER TO THE STRONGER
LOW OVER THE PLAINS. HOWEVER...WARM AND MOIST AIR FROM THE GULF OF
MEXICO AND ATLANTIC OCEAN WILL OVERRUN THE COLDER AND DRIER AIR
THAT IS CURRENTLY IN PLACE. THIS WILL CAUSE CLOUDS TO INCREASE
OVERNIGHT AND PRECIPITATION IS EXPECTED TO OVERSPREAD AT LEAST
PORTIONS OF THE AREA MONDAY MORNING INTO MONDAY AFTERNOON. 

THERE WILL BE ENOUGH COLD AIR FOR POSSIBLE FROZEN PRECIPITATION
MONDAY...ESPECIALLY NORTH AND WEST OF INTERSTATE 95. THE MAIN
IMPACT FROM FROZEN PRECIPITATION WOULD BE FROM FREEZING
RAIN...ALTHOUGH SNOW AND SLEET MAY MIX WITH
PRECIPITATION...ESPECIALLY AT THE ONSET. HOWEVER...THERE IS STILL
SOME UNCERTAINTY AS TO HOW FAR NORTH AND WEST THE PRECIPITATION
WILL MAKE IT SINCE IT WILL BE RUNNING INTO DRIER AIR. THE HIGHEST
CONFIDENCE FOR PRECIPITATION AND SUBFREEZING TEMPERATURES IS
ACROSS CENTRAL VIRGINIA. A FREEZING RAIN ADVISORY IS IN EFFECT FOR
THESE AREAS MONDAY MORNING. FREEZING RAIN MAY CONTINUE INTO THE
AFTERNOON HOURS AS WELL. 

FOR THE WASHINGTON AND BALTIMORE METROPOLITAN
AREAS...CONFIDENCE IS NOT YET HIGH ENOUGH FOR A HEADLINE SINCE
TEMPERATURES WILL BE MARGINAL AND IMPACT FROM FROZEN PRECIPITATION
IS NOT EXPECTED TO OCCUR UNTIL LATER MONDAY MORNING OR AFTERNOON.
PRECIPITATION WILL LIKELY OVERSPREAD THESE AREAS DURING THE MID TO
LATE MORNING HOURS MONDAY AND CONTINUE THROUGH MONDAY AFTERNOON.
FROZEN PRECIPITATION IS POSSIBLE...ESPECIALLY NORTH AND WEST OF
INTERSTATE 95. A FREEZING RAIN ADVISORY MAY BE NEEDED FOR PORTIONS
OF THESE AREAS. 

FOR THE POTOMAC HIGHLANDS...NORTHERN MARYLAND AND EASTERN WEST
VIRGINIA. TEMPERATURES WILL BE COLD ENOUGH FOR FROZEN
PRECIPITATION...BUT THE NORTHERN AND WESTERN EXTENT OF THE PRECIP
IS TOO UNCERTAIN AT THIS TIME TO ISSUE AN ADVISORY. ANY IMPACT
FROM FROZEN PRECIPITATION WOULD NOT OCCUR UNTIL MONDAY AFTERNOON. 

MAX TEMPS MONDAY WILL RANGE FROM THE UPPER 20S AND LOWER 30S
ACROSS THE ALLEGHENY AND POTOMAC HIGHLANDS...TO THE MIDDLE 30S
NEAR WASHINGTON AND BALTIMORE...TO NEAR 40 IN SOUTHERN MARYLAND. 

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
LIGHT PRECIPITATION WILL CONTINUE MONDAY NIGHT INTO TUESDAY MORNING. 
THE BIG QUESTION WILL BE HOW LONG THE CAD WEDGE WILL REMAIN IN 
PLACE. THERE IS STILL POTENTIAL FOR TEMPERATURES TO REMAIN AT OR 
BELOW FREEZING MAINLY WEST OF THE BLUE RIDGE LEAVING THE POTENTIAL 
FOR LIGHT FREEZING RAIN TO CONTINUE. TO THE EAST OF THE BLUE RIDGE 
AND ACROSS THE METRO AREAS...WARMER AIR WILL LIKELY WIN OUT KEEPING 
PRECIPITATION IN THE FORM OF RAIN. A BRIEF RESPITE FROM THE 
PRECIPITATION IS POSSIBLE TUESDAY AFTERNOON/EVENING BEFORE THE NEXT 
ROUND OF RAINFALL MOVES IN FROM THE WEST LATER TUESDAY NIGHT. 

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
STRONG COLD FRONT CROSSING THE MID ATLANTIC REGION WEDNESDAY INTO 
THURSDAY. LIQUID PRECIPITATION SHOULD ACCOMPANY THE FRONT EXCEPT 
ALONG THE ALLEGHENY  FRONT WHERE ARRIVAL OF COLDER AIR WILL CAUSE THE 
RAIN TO CHANGE OVER TO SNOW BEFORE PRECIPITATION ENDS THURSDAY.

PASSAGE OF SHORTWAVE WILL SUPPORT DEVELOPMENT OF A COASTAL LOW LATE 
SATURDAY AND SUNDAY. PRECIPITATION MAY START AS A WINTRY MIX AT 
HIGHER ELEVATIONS.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
VFR CONDITIONS THROUGH THIS EVENING. CLOUDS WILL INCREASE
OVERNIGHT AND PRECIPITATION WILL OVERSPREAD THE TERMINALS MONDAY
FROM SOUTHWEST TO NORTHEAST. FREEZING RAIN IS EXPECTED ACROSS KCHO
AND POSSIBLY KMRB AND KIAD. FREEZING RAIN MAY MIX WITH SLEET AND
SNOW AT THE ONSET. RAIN IS EXPECTED ACROSS THE REST OF THE
TERMINALS. RAIN MAY MIX WITH SLEET AT THE ONSET. CIGS/VSBYS WILL
DETERIORATE TO MVFR LEVELS MONDAY WITH POSSIBLE IFR LEVELS.

SUB VFR CIGS AND VSBYS EXPECTED MONDAY NIGHT INTO TUESDAY. LIGHT 
FREEZING RAIN WILL BE POSSIBLE WEST OF THE BLUE RIDGE WITH RAIN TO 
THE EAST. A PRECIPITATION RESPITE MAY OCCUR TUESDAY AFTERNOON BEFORE 
RAIN MOVES BACK IN LATER TUESDAY NIGHT. A STRONG COLD FRONT WILL
APPROACH THE TERMINALS WEDNESDAY BEFORE PASSING THROUGH
WEDNESDAY NIGHT. MORE RAIN AND SUBVFR CONDITIONS ARE EXPECTED. 

&&

.MARINE...
HIGH PRESSURE WILL REMAIN OVER THE WATERS TONIGHT. LOW PRESSURE
WILL TRACK UP THE MID-ATLANTIC COAST MONDAY. A SMALL CRAFT
ADVISORY IS IN EFFECT FOR THE MIDDLE PORTIONS OF THE BAY AND LOWER
TIDAL POTOMAC RIVER. 

WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA MONDAY NIGHT THROUGH 
TUESDAY NIGHT. A STRONG COLD FRONT WILL APPROACH THE WATERS
WEDNESDAY BEFORE PASSING THROUGH WEDNESDAY NIGHT. A SMALL CRAFT
ADVISORY WILL LIKELY BE NEEDED FOR THE WATERS WEDNESDAY AND
THURSDAY. 

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...FREEZING RAIN ADVISORY FROM 6 AM TO NOON EST MONDAY FOR VAZ025-
     026-029-036>040-050-051-501>504-507-508.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EST MONDAY FOR ANZ534-
     537-543.

&&

$$
SYNOPSIS...BJL
NEAR TERM...BJL
SHORT TERM...KRW
LONG TERM...CEM
AVIATION...BJL/KRW
MARINE...BJL/KRW

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