Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 200153
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
853 PM EST WED NOV 19 2014

.SYNOPSIS...
A COLD FRONT WILL PASS THROUGH THE REGION THURSDAY. 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 /UNTIL 6 AM THURSDAY MORNING/...
MID-LEVEL SHORTWAVE APPROACHES THE MID-ATLANTIC FROM THE WEST
TONIGHT. AT 01Z...THERE WAS AN ASSOCIATED COLD FRONT AT THE
SURFACE LOCATED OVER THE EASTERN OHIO VALLEY.

SHORTWAVE WILL BRING SOME CLOUDS INTO THE CWA...BUT IS RATHER
MOISTURE STARVED /LOW LEVELS ARE STILL VERY DRY TOO/ AND
THEREFORE ONLY EXPECT SNOW SHOWERS OVER THE POTOMAC HIGHLANDS
WHERE OROGRAPHIC LIFT WILL PLAY A ROLE...PARTICULARLY OVER THE
WESTERN SLOPES AFTER WINDS SHIFT TO THE WEST BEHIND THE COLD
FRONT.

FOR TEMPERATURES...CLOUDS WILL BE A FACTOR HOW LOW WE GO. OVERALL
TREND IS FOR IT TO NOT BE AS COLD AS LAST NIGHT WITH SOME
CLOUDS/WARM ADVECTION/SOUTHERLY WINDS. RE-POPULATED USING A BLEND
OF LATEST BC ADJMET AND BC SREFS.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
THE COLD FRONT WILL MOVE ACROSS THE AREA THURSDAY. SOME
ADDITIONAL UPSLOPE SNOW IS POSSIBLE OVER THE POTOMAC
HIGHLANDS...BUT ALL OTHER AREAS ARE EXPECTED TO REMAIN DRY. WINDS
WILL SHIFT TO THE WEST AFTER THE FRONTAL PASSAGE...WITH POTENTIAL
FOR SOME GUSTS OF 15-20 KTS. DOWNSLOPING WILL CONTRIBUTE TO WARMER
HIGH TEMPS IN THE AFTERNOON....WITH HIGHS IN THE LOW TO MID 40S.
IT WILL BE COOLER IN THE POTOMAC HIGHLANDS..WITH HIGHS IN THE
UPPER 20S AND 30S.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
AN UPPER LEVEL TROUGH WILL BE MOVING ACROSS NEW ENGLAND THURSDAY
NIGHT WHILE SFC LOW PRESSURE HEADS TOWARDS NOVA SCOTIA. THE
MID-ATLANTIC WILL BE POST-FRONTAL AND WESTERLY WINDS WILL LEAD TO
COLD AIR ADVECTION THURSDAY NIGHT AND INTO FRIDAY. FCST MIN TEMPS
WILL RANGE FROM THE TEENS ACROSS THE HIGHLANDS TO THE MID TO UPPER
20S ACROSS THE I-95 CORRIDOR. W-NW WINDS AGAINST THE ALLEGHENY FRONT SHOULD
PRODUCE SNOW SHOWERS ACROSS THE WESTERN SLOPES THURSDAY NIGHT. SNOW
SHOWERS AND UPSLOPE CONDITIONS WILL DIMINISH BY FRIDAY AS SUBSIDENCE
SETS IN. LITTLE TO NO ACCUMULATION IS EXPECTED.

HIGH PRESSURE WILL MOVE INTO THE REGION FRIDAY. NW WINDS WILL
CONTINUE FRIDAY WITH FCST MAX TEMPS STAYING BELOW NORMAL...UPPER
20S/LOW 30S ACROSS THE HIGHLANDS TO THE MID TO UPPER 30S ACROSS THE
PIEDMONT AND SOUTHERN MARYLAND. HIGH PRESSURE WILL MOVE OVERHEAD
FRIDAY NIGHT LEADING TO ANOTHER CHILLY NIGHT...FCST MIN TEMPS WILL RANGE
FROM THE TEENS IN THE MTNS OUT WEST AND THE LOW TO MID 20S ELSEWHERE.

HIGH PRESSURE WILL MOVE OFFSHORE SATURDAY AND SATURDAY NIGHT. WINDS
WILL BECOME SOUTHERLY AHEAD OF A STORM SYSTEM AND COLD FRONT WHICH
WILL PIVOT NORTHEASTWARD FROM THE CENTRAL OHIO VALLEY TO THE GREAT
LAKES DURING THE DAY SUNDAY.

THERE IS A SLIGHT CHANCE OF A FEW RAIN OR SNOW SHOWERS ALONG THE
MASON DIXON LINE LATE SATURDAY NIGHT AND EARLY SUNDAY AS UPPER LEVEL
ENERGY SLIDES ACROSS THE LOWER GREAT LAKES REGION.

TEMPERATURES WILL MODIFY SATURDAY NIGHT THROUGH MONDAY. SOME LIGHT
RAIN WILL MOVE INTO THE REGION SUNDAY AND QUICKLY OVERSPREADING THE
ENTIRE REGION LATER SUNDAY AND SUNDAY NIGHT. THERE IS A CHANCE OF A
FEW LINGERING RAIN SHOWERS MONDAY INTO MONDAY NIGHT BUT THE HIGHER
PROBABILITIES OF RAIN WOULD BE SUNDAY AND SUNDAY NIGHT.

A TRAILING COLD FRONT WILL GRADUALLY MOVE EAST MONDAY NIGHT INTO
TUESDAY. ALTHOUGH MOST RAIN ACTIVITY SHOULD BE OFFSHORE TUESDAY...WE
CAN`T RULE OUT A FEW LINGER RAIN SHOWERS ALONG AND ON THE COLD SIDE
OF THE TRAILING FRONT. AN AREA OF LOW PRESSURE COULD DEVELOP ALONG
THE FRONT NEAR THE CAROLINAS AND TREK NORTHEAST ACROSS THE OPEN
ATLANTIC. THERE IS A SLIGHT CHANCE OF RAIN SHOWERS NEAR THE
CHESAPEAKE BAY AREA.

HIGH PRESSURE WILL NOSE ITS WAY INTO THE REGION FROM THE WEST
WEDNESDAY. TEMPERATURES WILL BE ABOUT 10 DEGREES COOLER THAN TUESDAY
ONCE THE COASTAL LOW PULLS AWAY AND CHILLY HIGH PRESSURE SETTLES
INTO THE REGION.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR CONDITIONS CONTINUE OVERNIGHT AND THROUGH THURSDAY AFTERNOON.
WINDS WILL SHIFT TO THE SW OVERNIGHT AND TO THE W THURSDAY BEHIND
A COLD FRONT. GUSTS 15 TO 20 KT LIKELY LATE THURSDAY MORNING AND
AFTERNOON.

VFR CONDITIONS EXPECTED THURSDAY NIGHT THROUGH FRIDAY NIGHT. W-NW
WINDS EXPECTED DURING THIS TIME. VFR CONDITIONS SATURDAY INTO
SATURDAY NIGHT. WINDS WILL BECOME SOUTHERLY AT 5 TO 10 KNOTS.

VFR CONDITIONS SUNDAY MORNING COULD QUICKLY BECOME IFR OR EVEN LIFR
AS LIGHT TO OCCASIONALLY MODERATE RAIN OVERSPREADS THE REGION FROM
THE SOUTHWEST. WINDS WILL START SOUTHERLY BUT BECOME MORE EASTERLY
AT 10 TO 20 KNOTS GUSTING 25 TO 30 KNOTS.

&&

.MARINE...
SOUTHERLY WINDS WERE EFFICIENTLY CHANNELLING UP THE BAY THIS
EVENING...WITH TPLM2 LAST HOUR 25G29KT. DON/T EXPECT WINDS TO GO
OVER 30 KT...BUT HIGH END SCA IS EXPECTED THROUGH THE NIGHT UP
THE BAY AND ALSO ACROSS THE EXTREME LOWER TIDAL POTOMAC RIVER.
COLD FRONT MOVES THROUGH THURSDAY...WITH WINDS SWITCHING TO THE
WEST AND LIKELY GUSTING AOA 20 KT ALL WATERS BY AFTERNOON.

THE WATERS WILL BE POST-FRONTAL THURSDAY NIGHT AND GUSTY W-NW
WINDS ARE EXPECTED ACROSS THE LOWER TIDAL POTOMAC AND MARYLAND
CHESAPEAKE BAY SOUTH OF POOLES ISLAND. AS HIGH PRESSURE MOVES INTO
THE REGION FRIDAY...WINDS WILL STILL BE GUSTY AS A TIGHT PRESSURE
GRADIENT WILL BE OVER THE WATERS. THE SCA WILL LIKELY NEED TO BE
EXTENDED INTO FRIDAY.

SMALL CRAFT ADVISORIES ARE POSSIBLE SATURDAY NIGHT THROUGH
SUNDAY. WINDS WILL BE MAINLY SOUTHWEST 15 KNOTS GUSTS TO 25 KNOTS
SATURDAY NIGHT. WINDS WILL BECOME SOUTH TO SOUTHEASTERLY 15 TO 20
KNOTS GUSTS TO 30 KNOTS SUNDAY.

&&

.CLIMATE...
RECORD COLD IS JUST ABOUT TO RELEASE ITS HOLD ON THE AREA...ONLY TO
GIVE WAY TO ANOTHER SHOT OF COLD AIR BEHIND A COLD FRONT TOMORROW.
THIS SECOND WAVE OF COLD AIR WILL NOT BE AS SEVERE...BUT WILL KEEP
TEMPERATURES BELOW NORMAL THROUGH THE FIRST HALF OF THE WEEKEND.

IN FACT...HIGH TEMPERATURES ARE FORECAST TO REMAIN BELOW 50 DEGREES
AT IAD AND BWI THROUGH SATURDAY. IF THIS HAPPENS...BOTH SITES WILL
HAVE THE LONGEST STRETCH OF DAYS BELOW 50 DEGREES IN NOVEMBER ON
RECORD.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ531>534-
     537>543.
     SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ530.
     SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EST THURSDAY FOR ANZ535-
     536.

&&

$$
SYNOPSIS...KS
NEAR TERM...BPP
SHORT TERM...KS
LONG TERM...HAS/KLW
AVIATION...BPP/HAS/KS/KLW
MARINE...BPP/HAS/KS/KLW
CLIMATE...DFH






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