Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 171923
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
323 PM EDT FRI OCT 17 2014

.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL SWING EAST THROUGH THE WESTERN GREAT
LAKES TODAY AND ACROSS THE MID-ATLANTIC THROUGH SATURDAY NIGHT. AN
UPPER CUT OFF LOW WILL LIKELY AFFECT THE REGION FOR MUCH OF THE
COMING WEEK.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
AN UPPER LEVEL TROUGH IS LOCATED ACROSS THE GREAT LAKES TODAY.
WESTERLY FLOW ALOFT WILL BECOME SOUTHWESTERLY AS A SHORTWAVE TROUGH
MOVES ACROSS THE LOWER GREAT LAKES TONIGHT. THIS WILL INCREASE
MOISTURE ACROSS THE MID-ATLANTIC BUT DUE TO OVERALL DRY CONDITIONS
THE REGION SHOULD STAY MOSTLY CLEAR WITH THE EXCEPTION OF CLOUDS
ALONG THE ALLEGHENY SLOPE/UPSLOPE REGION. FCST MIN TEMPS WILL RANGE
FROM THE 40S IN THE HIGHLANDS TO UPPER 50S IN THE CITY CENTERS.

FLOW ALOFT BECOMES MORE ZONAL AS A COLD FRONT MOVES ACROSS THE
REGION SATURDAY MORNING. A STRATO-CU FIELD IS EXPECTED AND WILL LIKELY BE
MORE WIDESPREAD THAN TODAY...FRIDAY. AN ISOLATED RAIN SHOWER IS
POSSIBLE ACROSS THE POTOMAC HIGHLANDS AND NORTHERN VA SATURDAY
AFTERNOON. W-NW WINDS ARE ALSO EXPECTED SATURDAY AND GUSTS UP TO
30 MPH ARE POSSIBLE SAT AFTERNOON. HIGH PRESSURE WILL MOVE INTO
THE REGION SATURDAY NIGHT AS ANOTHER SHORTWAVE TROUGH MOVES
OVERHEAD. AT THIS TIME...MODELS ARE SHOWING LITTLE TO NO RAIN WITH
THIS FEATURE AS COLD AIR ADVECTION OCCURS THROUGHOUT THE COLUMN.
SHOWERS ARE LIKELY IN THE UPSLOPE REGION AS NW FLOW MOVES UP
AGAINST THE ALLEGHENY FRONT SAT NIGHT. TEMPS WILL LIKELY DROP INTO
THE 30S IN THIS REGION BY SUN MORNING. SHOWERS ARE EXPECTED TO
TAPER OFF BUT BEFORE THEY DO SOME SNOWFLAKES MAY MIX IN BEFORE
SUNRISE SUNDAY MORNING.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
HIGH PRESSURE MOVES OVERHEAD SUNDAY AS A UPPER LEVEL RIDGE
APPROACHES FROM THE WEST. SUNDAY WILL FEEL COOL WITH MAX TEMPS
ONLY REACHING THE UPPER 40S IN THE HIGHLANDS AND UPPER 50S NEAR 60
ACROSS THE PIEDMONT AND SOUTHERN MD.

HIGH PRESSURE WILL MOVE OFF THE COAST MONDAY AND SOUTHERLY FLOW
WILL HELP TEMPS WARM BY A FEW MORE DEGREES THAN SUNDAY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ECMWF 500MB TROUGH MOVING EAST ACROSS THE MIDWEST THROUGH EARLY HALF
OF THE WEEK. SHORTWAVES DIGGING DOWN TROUGH ALSO CAUSING IT TO
DEEPEN DURING THE PERIOD. CUT-OFF LOW FORMING OVER UPPER OHIO VALLEY
AT MID WEEK WILL CROSS MID ATLANTIC REGION DURING THE LATTER HALF OF
THE WEEK.

TRACK OF SURFACE LOW IS LIKELY TO PERMIT GREATEST OF OPPORTUNITY OF
PRECIPITATION TO OCCUR OVER CWA TUESDAY NIGHT THROUGH WEDNESDAY AND
AGAIN THURSDAY. INCREASING WINDS EXPECTED WEDNESDAY THROUGH FRIDAY
AS PRESSURE GRADIENT TIGHTENING UP WHEN LOW PUSHES OFFSHORE AND
SLOWLY MOVES NORTHEASTWARD.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
S WINDS 10-15KTS WILL CONTINUE THIS AFTERNOON. ISO-SCT CU FIELD
WILL DIMINISH AROUND SUNRISE AND TERMINALS ARE EXPECTED TO BE VFR
TONIGHT AND SATURDAY. WINDS BECOME W-NW SATURDAY AT 10-15KTS WITH
GUSTS UP TO 25 KTS BY AFTERNOON.

W-NW BREEZY WINDS WILL CONTINUE INTO SUNDAY WITH GUSTS UP TO 25
KTS POSSIBLE SUN AFTERNOON. MAINLY DRY INTO EARLY NEXT
WEEK...THOUGH ANOTHER SLOW-MOVING LOW PRESSURE SYSTEM MAY AFFECT
THE REGION DURING THE MIDDLE PART OF NEXT WEEK. NOT NEARLY AS MUCH
PRECIP TO CONTEND W/ AS THE EXITING FEATURE BUT MAY SEE
PERIODICALLY LOWER CIGS AND SOME SCATTERED SHOWERS.

&&

.MARINE...
WINDS HAVE BECOME SOUTHERLY ACROSS THE WATERS THIS AFTERNOON
RESULTING IN 10-15KTS WITH OCCATIONAL GUSTS AROUND 17-19 KTS.
THESE GUSTS WILL BE ISOLATED AND THEREFORE SCA IS NOT IN EFFECT
THIS AFTERNOON. SW FLOW WILL INCREASE THIS EVENING ACROSS THE
LOWER TIDAL POTOMAC AND BAY SOUTH OF DRUM PT AND THE TANGIER
SOUND. A SCA IS IN EFFECT OVERNIGHT FOR THIS AREA. A DRY COLD
FRONT WILL CROSS THE WATERS SATURDAY MORNING AND W-NW WILL
INCREASE BEHIND IT. GUSTS UP TO 25 KTS ARE EXPECTED ON THE WATERS
SATURDAY. THESE WINDS MAY CONTINUE ON THE WATERS THROUGH SUNDAY
AND A SCA WILL LIKELY NEED TO BE EXPANDED IN TIME SAT NIGHT AND
THEN AGAIN FOR ALL THE WATERS ON SUN AFTN W/ ANOTHER UPPER WAVE
MIXING DOWN GUSTY WINDS. HIGH PRESSURE EXPECTED TO BUILD IN BEHIND
THIS WAVE TO START THE WORK WEEK.

&&

.TIDES/COASTAL FLOODING...
WATER LEVELS LESS THAN A HALF-FOOT ABV ASTRO NORMS. WINDS WILL
TURN SLY AND INCREASE THIS AFTERNOON. CBOFS PICKING UP ON THIS
AND BRINGING TIDES WELL INTO CAUTION STAGE /ALMOST TO MINOR FLOOD
STAGE AT ANNAPOLIS/ FOR TONIGHTS TIDE CYCLE. WHILE INCREASED
DEPARTURES PLAUSIBLE...THE MAGNITUDE OF THE CBOFS FORECAST DOES
NOT. DO NOT ANTICIPATE ADVYS AT THIS TIME.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EDT SATURDAY FOR
     ANZ530>533-535-536-538>542.
     SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM EDT
     SATURDAY FOR ANZ534-537-543.

&&

$$
SYNOPSIS...HAS
NEAR TERM...HAS
SHORT TERM...HAS
LONG TERM...CEM
AVIATION...HAS
MARINE...HAS
TIDES/COASTAL FLOODING...HTS






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