Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 181449
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
949 AM EST THU DEC 18 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE AREA TODAY AND PERSIST THROUGH
FRIDAY NIGHT...EXCEPT FOR A WEAK DISTURBANCE THAT WILL CROSS THE
AREA TONIGHT. LOW PRESSURE WILL TRACK SOUTH OF THE AREA SATURDAY
THROUGH SUNDAY. A SECONDARY LOW IS EXPECTED TO MOVE UP FROM THE
SOUTHEAST COAST EARLY NEXT WEEK. A LARGE AREA OF LOW PRESSURE
LOOKS TO DEVELOP IN THE OHIO VALLEY DURING THE MIDDLE OF NEXT
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
SFC HIGH PRESSURE CENTERED NEAR LAKE SUPERIOR WILL EXTEND SE
TOWARD THE AREA TODAY...WHILE STILL UNDER THE INFLUENCE WITH THE
PRESSURE GRADIENT TO LOW PRESSURE OVER THE CANADIAN MARITIMES.
STRATOCUMULUS EXTENDS ACROSS THE NORTHERN THIRD OF THE CWA AND HAS
ACTUALLY ADVANCE A BIT BACK TO THE SE OVER THE PAST FEW HOURS.
STILL THINK THIS LAYER CAN AT LEAST BECOME MORE SCATTERED WITH
DIURNAL MIXING...BUT MAY BE A SLOW PROCESS. ANOTHER SHORTWAVE
TROUGH IS QUICKLY APPROACHING FROM THE LOWER OHIO VALLEY. HI RES
MODELS CONTINUE TO SHOW PRECIP FIZZLING AS IT ENCOUNTERS DRIER AIR
MASS/HIGH PRESSURE...AND THE LAST COUPLE HOURS OF RADAR DATA
SUPPORT THE HYPOTHESIS. THERE IS A BETTER LATCHING ONTO THE
NORTHERN AREA SURVIVING ACROSS OHIO...SO WILL MONITOR RADAR TRENDS
AS TO WHETHER POPS MAY NEEDED TO BE ADDED LATE AFTERNOON/EVENING
IN THE NORTHERN MOUNTAINS. OTHERWISE JUST AN INCREASE IN MID LEVEL
CLOUDS EXPECTED. EXPECT THE SPORADIC WIND GUSTS TO BECOME MORE
COMMON TOWARD MIDDAY AS THE 20-25 KT SEEN ON THE 12Z KIAD SOUNDING
ARE ABLE TO MIX DOWN. SOUNDING ALSO SUPPORTS GOING HIGH
TEMPERATURES COMBINED WITH A BIT OF DOWNSLOPING...SO NO ADJUSTMENTS
THERE.

WL HV SOME CLDS FM THE SYSTEM IN THE CENTRL OF THE CONUS ADVCG EWD
BY END OF THE PD. WL BE MOCLDY AS A RESULT IN THE EVNG AS WV CROSSES
CWFA. NAM SUGGESTING SCHC POPS...MAYBE DUE TO A FLURRY OR TWO. AMS
LOOKS TOO DRY FOR THAT. WENT LWR THAN NAM POPS...PRECLUDING A
MENTION...BUT POP GRIDS NONZERO. TOOK TEMPS DOWN BY A CPL DEGF IN
CAA.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
OVERALL SYNOPTIC PTTN FRI SIMLR TO TDA...MINUS THE S/WVS. HV FEWER
CLDS IN THE GRIDS...AND SIMLR TEMPS. AFTR MIDNGT...WL HV MID DECK
CLDS FILLING IN FM THE SW...BUT FCST PACE OF STORM SYSTEM HAS
SLOWED...WHICH IMPACTS SKYCOVER. NE OF PTMC RIVER SKYCOVER MAY AVG
OUT NO WORSE THAN PTCLDY.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL BE CENTERED OVER QUEBEC AND EXTEND DOWN INTO THE
MID-ATLANTIC SATURDAY. A SHORTWAVE TROUGH WILL BE APPROACHING THE
OHIO VALLEY AND SOUTHERLY FLOW ALOFT WILL CAUSE MOISTURE
ADVECTION INTO THE REGION SATURDAY CAUSING CLOUDS TO BUILD IN FROM
THE SOUTHWEST. A JET STREAK WILL BE LOCATED ACROSS THE SE STATES
WITH MOST OF THE FORCING ACROSS THIS REGION INCLUDING THE
CAROLINAS SATURDAY INTO SATURDAY NIGHT. FLOW AT 850 VEERS WESTERLY
ACROSS THE MID-ATLANTIC SAT AFTERNOON AND SHUTS OFF MOISTURE
ADVECTION FROM THE GULF. THIS WILL RESULT IN LIGHTER PRECIP ACROSS
THE REGION. MOST OF THE MOISTURE WILL BE FURTHER SOUTH AND ACROSS
THE CAROLINAS. THE 3Z SREF MEAN HAS LINED UP MORE WITH THE
DETERMINISTIC RUNS SHOWING MOSTLY DRY CONDITIONS SATURDAY INTO
SUNDAY. TEMPS ARE EXPECTED TO CLIMB INTO THE 40S SATURDAY AND ANY
PRECIP WILL BE RAIN WITH THE EXCEPTION OF THE HIGHER ELEVATIONS
THAT WOULD SEE SNOW. LIGHT PRECIP IS EXPECTED AND THEREFORE LITTLE
TO NO ACCUMULATION OF SNOW IN THE MTNS IS EXPECTED AT THIS TIME.

THE SHORTWAVE TROUGH WILL MOVE OFF THE EAST COAST BY SUNDAY AND
RIDGING WILL ALLOW DRIER AIR TO FILTER IN FROM THE WEST. A BRIEF
PERIOD OF CALM WEATHER IS EXPECTED SUNDAY BEFORE THE NEXT SYSTEM
BEGINS TO FORM OFF THE SE COAST SUNDAY NIGHT. A TROUGH WILL MOVE
INTO THE GULF COAST STATES AND CYCLOGENESIS IS EXPECTED TO TAKE
PLACE OFF THE SOUTHEAST COAST MONDAY INTO TUESDAY. TEMPS ARE
FORECAST TO BE ABOVE FREEZING WITH THE EXCEPTION OF THE HIGHER
ELEVATIONS MONDAY NIGHT. MOSTLY RAIN IS EXPECTED DURING THIS TIME.
LOW PRESSURE SHOULD MOVE AWAY FROM THE MID-ATLANTIC TUESDAY. LITTLE
RELIEF IS EXPECTED AS THE NEXT STRONG SYSTEM MOVES INTO THE GREAT
LAKES REGION MIDWEEK. TIMING IS EVERYTHING AND MOISTURE WITH THIS
SYSTEMS SEEMS TO BE PRE-FRONT AND THEREFORE THE MID=ATLANTIC WOULD
SEE MOSTLY RAIN.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
VFR CONDITIONS TODAY WITH BKN CIGS AT TIMES 040-050 (EXCEPT CHO)
AND WIND GUSTS TO 20KT POSSIBLE. CIGS WILL SCATTER OUT BY THIS
AFTERNOON. THE GUSTY NW WINDS WILL BECOME MORE CONSISTENT THROUGH
THIS AFTERNOON...THEN DIMINISH BY EVENING.

WL HV A PD OF MID DECK CLDS THIS EVNG. THINK WNDS WL SUBSIDE AT THE
SFC...BUT WL STILL HV 20-25 KT FLOW 1000 FT UP. NOT ENUF TO QUALIFY
FOR LLWS.

VFR CONTS FRI-FRI NGT. ANTHR PD OF GUSTY NW WINDS MIDDAY UP TO 20
KT. ONCE AGN...MID DECK CLDS WL OVERSPREAD TERMINALS AT NGT.

NO SIGNIFICANT WEATHER EXPECTED SATURDAY AND SUNDAY.

&&

.MARINE...
SCA CALIBER GUSTS WILL CONTINUE THROUGH THE AFTERNOON. MORNING
ANALYSIS SUGGESTS NW GUSTS 20-25 KT WITH MIXING. THESE WINDS WILL
DIMINISH THROUGH THE AFTERNOON...NO CHANGES TO THE SCA DROPPING
OFF AT 19Z FOR THE UPPER POTOMAC AND 00Z ELSEWHERE.

GDNC SUGGESTING THAT FLOW WL PARTIALLY DCPL TNGT. AM NOT CERTAIN
OF THAT...BUT WL CAP WNDS JUST BLO FOR THE NIGHT TIME PD. THE
OPPORTUNITY FOR MIXING RENEWS AFTER SUNRISE FRI. HV ISSUED ANTHR
SCA FOR MOST OF THE BAY AND LWR PTMC RIVER THRU MID AFTN.

A DISTURBANCE WILL MOVE SOUTH OF THE WATERS SATURDAY AND SUNDAY. AN
ACTIVE PERIOD IS EXPECTED NEXT WEEK. COASTAL LOW PRESSURE MAY IMPACT
THE WATERS MONDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     ANZ530>534-537>543.
     SMALL CRAFT ADVISORY FROM 7 AM TO 3 PM EST FRIDAY FOR
     ANZ531>534-537>543.
     SMALL CRAFT ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR ANZ535-
     536.

&&

$$
SYNOPSIS...HTS
NEAR TERM...ADS/HTS
SHORT TERM...HTS
LONG TERM...HAS
AVIATION...ADS/HAS/HTS
MARINE...ADS/HAS/HTS







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