Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 191141 AAA
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
641 AM EST WED NOV 19 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE DEEP SOUTH THROUGH TONIGHT. A
DRY COLD FRONT WILL PASS THROUGH THE REGION LATE THURSDAY INTO
THURSDAY EVENING. HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT
FRIDAY THROUGH FRIDAY NIGHT BEFORE MOVING OFF THE COAST SATURDAY.
A WARM FRONT WILL CROSS THE AREA SUNDAY INTO MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...

.UPDATE...
EXPANDED THE WIND CHILL ADVISORY FOR PORTIONS OF THE POTOMAC
HIGHLANDS ABOVE 3000 FEET UNTIL 9 AM BASED ON LATEST ANALYSIS AND
OBSERVATIONS. WIND CHILLS ARE STILL RUNNING IN THE -5 TO -11 RANGE
WITH WESTERLY WINDS OF 10-20 MPH AND TEMPS IN THE SINGLE DIGITS.
TEMPERATURES WILL GRADUALLY MODERATE AFTER SUNRISE WITH WIND
CHILLS COMING DOWN BELOW ADVISORY LEVELS BY MID MORNING.

.PREVIOUS DISCUSSION...
UNDER MOSTLY CLEAR SKIES AND LIGHT WINDS...TEMPERATURES HAVE FALLEN
OFF INTO THE TEENS AND 20S IN MOST AREAS EXCEPT SINGLE DIGITS OVER
THE POTOMAC HIGHLANDS. READINGS WILL LIKELY FALL OFF A BIT MORE
BEFORE SUNRISE.

HIGH PRESSURE WILL SLIDE OFF THE EAST COAST DURING TODAY AS AN UPPER
TROUGH SWINGS EAST ACROSS THE GREAT LAKES. MID AND HIGH LEVEL CLOUDS
WILL INCREASE FROM WEST TO EAST DURING THE DAY AND WINDS WILL ALSO
SHIFT INTO THE SOUTH. EVEN WITH A SOUTHERLY WIND COMPONENT IN
PLACE...TEMPERATURES WILL STILL REMAIN WELL BELOW NORMAL DURING THE
DAY. HIGHS WILL ONLY REACH THE 30S...WITH 20S OVER THE HIGHER
ELEVATIONS. WINDS WILL SHIFT BACK TO THE WEST AS A WEAK FRONT
PUSHES EAST ACROSS THE REGION. UPSLOPE COMPONENT TO THE FLOW WILL
AID IN THE DEVELOPMENT OF SOME SNOW SHOWER ACTIVITY OVER THE
POTOMAC HIGHLANDS WITH LIGHT ACCUMULATIONS UNDER AN INCH EXPECTED.
OVERNIGHT LOWS WILL NOT BE AS COLD. READINGS WILL RANGE FROM THE
LOWER TO MIDDLE 20S IN THE COLDER LOCALES TO THE UPPER 20S TO NEAR
30 IN THE METRO AREAS.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
BREEZY WESTERLY WINDS WILL DEVELOP ON THURSDAY. TEMPERATURES ARE
EXPECTED TO MODERATE INTO THE 40S EAST OF THE BLUE RIDGE WITH 30S
OVER THE HIGHER TERRAIN. ANOTHER RE-ENFORCING SHOT OF COLD AIR WILL
FILTER INTO THE REGION DURING THE DAY...SETTING UP COLDER
TEMPERATURES OVERNIGHT.

THE DRY COLD FRONT WILL MOVE OFF TO OUR EAST THURSDAY NIGHT WHILE
ARCTIC HIGH PRESSURE APPROACHES FROM THE OHIO VALLEY. A WEST TO
NORTHWEST FLOW BETWEEN THESE SYSTEMS WILL CONTINUE TO USHER IN
UNUSUALLY COLD CONDITIONS FOR THIS TIME OF YEAR. MIN TEMPS WILL
RANGE FROM THE SINGLE DIGITS AND LOWER TEENS IN THE ALLEGHENY
HIGHLANDS TO THE MID AND UPPER 20S IN DOWNTOWN WASHINGTON AND
BALTIMORE.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD TOWARD THE REGION
FRIDAY AND A NORTHWEST FLOW WILL CONTINUE TO USHER IN VERY COLD
CONDITIONS FOR THIS TIME OF YEAR. IN FACT...MAX TEMPS WERE TWEAKED
DOWN CLOSER TO THE MAV/MET GUIDANCE WHICH SEEMS TO FIT GIVEN THE
TEMPS ALOFT. THE HIGH WILL SETTLE OVERHEAD FRIDAY NIGHT. LEANED
COLDER WITH THE FORECAST SINCE THERE WILL BE LIGHT WINDS...DRY AIR
AND MAINLY CLEAR SKIES THAT WILL ALLOW FOR RADIATIONAL COOLING.

THE HIGH WILL MOVE OFF THE COAST SATURDAY AND A SOUTHERLY FLOW
WILL DEVELOP...ALLOWING FOR MILDER CONDITIONS COMPARED TO RECENT
DAYS. HOWEVER...IT WILL REMAIN CHILLY FOR THIS TIME OF YEAR.

THE NEXT STORM SYSTEM OVER THE GULF COAST STATES SATURDAY NIGHT IS
EXPECTED TO MOVE NORTHEAST INTO THE GREAT LAKES SUNDAY AND INTO
CANADA MONDAY. WITH THE STORM TRACK TO OUR WEST...THIS WILL ALLOW
FOR WARMER AIR TO MOVE INTO THE AREA DURING THIS TIME. IN
FACT...THE WARM FRONT FROM THIS SYSTEM IS MOST LIKELY TO MOVE
THROUGH SUNDAY INTO EARLY MONDAY. THERE SHOULD BE DEEP OVERRUNNING
AHEAD OF THE BOUNDARY AS WARM AND MOIST AIR FROM THE GULF OF
MEXICO AND ATLANTIC OCEAN OVERRUN THE SURFACE COOLER AIR IN PLACE.
THIS WILL RESULT IN A PERIOD OF RAIN AND ALTHOUGH TIMING IS
UNCERTAIN THIS FAR OUT IT DOES APPEAR THAT THE BEST CHANCE FOR
RAIN WILL BE SUNDAY AFTERNOON AND EVENING.

THE LOW WILL TRACK TOWARD THE HUDSON BAY MONDAY AND THE COLD FRONT
ASSOCIATED WITH THIS SYSTEM WILL APPROACH FROM THE WEST. A STRONG
SOUTHERLY FLOW AHEAD OF THE BOUNDARY WILL USHER IN MUCH WARMER
CONDITIONS COMPARED TO RECENT DAYS. IN FACT...MAX TEMPS WELL INTO
THE 60S ARE EXPECTED AND A FEW AREAS MAY EVEN APPROACH THE 70
DEGREE MARK. THE COLD FRONT WILL PASS THROUGH THE AREA MONDAY
NIGHT AND A RETURN OF DRIER AND SEASONABLE CONDITIONS ARE EXPECTED
TOWARD THE MIDDLE PORTION OF NEXT WEEK.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
VFR CONDITIONS EXPECTED TODAY. AN INCREASE IN MID TO HIGH LEVEL
CLOUDS CAN BE EXPECTED A BIT LATER IN THE DAY AS A TROUGH OF LOW
PRESSURE CROSSES THE GREAT LAKES. WINDS WILL ALSO SHIFT INTO THE
SOUTH AT AROUND 10KTS DURING THE DAY. VFR CONDITIONS WILL PERSIST
WEDNESDAY NIGHT AND THURSDAY WITH BREEZY CONDITIONS DEVELOPING WITH
THE NEXT FRONT.

VFR CONDITIONS ARE EXPECTED THURSDAY NIGHT THROUGH SATURDAY NIGHT.
RAIN AND SUBVFR CONDITIONS WILL DEVELOP LATER SUNDAY THROUGH
SUNDAY NIGHT.

&&

.MARINE...
SMALL CRAFT CONDITIONS EXPECTED FOR THE FIRST PART OF TODAY AND
AGAIN WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF ANOTHER FRONT.

A DRY COLD FRONT WILL MOVE OFF TO THE EAST THURSDAY NIGHT. A
NORTHWEST FLOW IS EXPECTED BEHIND THIS SYSTEM THROUGH FRIDAY AND
INTO FRIDAY NIGHT. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED
FOR PORTIONS OF THE WATERS DURING THIS TIME. THE HIGH WILL BUILD
OVERHEAD LATER FRIDAY NIGHT BEFORE MOVING OFF THE COAST SATURDAY.
A SOUTHERLY FLOW WILL INCREASE SUNDAY AND MONDAY AHEAD OF A COLD
FRONT. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR PORTIONS
OF THE WATERS DURING THIS TIME.

&&

.CLIMATE...
BITTERLY COLD CONDITIONS ARE OCCURRING EARLY THIS MORNING. THE
RECORD LOW FOR DULLES TODAY HAS ALREADY BEEN BROKEN AND THE RECORD
LOW FOR BWI WILL BE CHALLANGED AS WELL. ALSO...THE RECORD LOW FOR
TUESDAY...NOVEMBER 18TH WAS BROKEN AT WASHINGTON DULLES. THE LOW
WAS 18 DEGREES BREAKING THE OLD RECORD OF 20 SET IN 1991.

BELOW IS A LIST OF THE RECORD LOW TEMPERATURES AND RECORD LOW
MAXIMUM TEMPERATURES FOR TODAY...NOVEMBER 19TH.

SITE 11/19 RECORD LOW      11/19 LOW MAX
DCA        18 (1891)           33 (1880)
BWI        20 (1936)           35 (1880)
IAD        20 (1990)           38 (2008)

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...WIND CHILL ADVISORY UNTIL 9 AM EST THIS MORNING FOR VAZ503-504.
WV...WIND CHILL ADVISORY UNTIL 9 AM EST THIS MORNING FOR WVZ501-505-
     506.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR
     ANZ530>534-537-539>541-543.
     SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM EST
     THURSDAY FOR ANZ530>534-537>543.
     SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EST THURSDAY FOR ANZ535-
     536.

&&

$$
SYNOPSIS...BJL
NEAR TERM/UPDATE/...KRW
SHORT TERM...BJL/KRW
LONG TERM...BJL
AVIATION...BJL/KRW
MARINE...BJL/KRW
CLIMATE...DFH/BAJ







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