Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 200852 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 352 AM EST SAT DEC 20 2014 .SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE WILL PERSIST THROUGH SUNDAY. LOW PRESSURE WILL TRACK UP THE MID-ATLANTIC COAST LATE MONDAY. A STRONG COLD FRONT WILL THEN PASS THROUGH THE AREA LATE WEDNESDAY.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
THE MID ATLANTIC IS BETWEEN TWO SHORTWAVE TROUGHS THIS MORNING...ONE ACROSS NEW YORK AND ANOTHER APPROACHING FROM THE OHIO VALLEY. HIGH PRESSURE IS CENTERED OVERHEAD AND HAS LED TO CALM AND DRY CONDITIONS THIS MORNING. MOISTURE ADVECTION FROM SW FLOW ALOFT WILL CONTINUE AHEAD OF THE APPROACHING SHORTWAVE TROUGH AND CIRRUS WILL CONTINUE TO MOVE INTO THE REGION FROM SW TO NE THIS MORNING. PRECIPITATION ACROSS THE SE US WILL CONTINUE TO MOVE NORTH-NORTHEAST THIS MORNING. THERE IS A SLIGHT CHANCE OF SNOW TO SKIM THE CENTRAL FOOTHILLS BEFORE NOON TODAY AS MOISTURE MOVES NORTHWARD. IT IS NOT LIKELY AS SW FLOW ALOFT IS EXPECTED TO BECOME WESTERLY MIDDAY LIMITING MOISTURE ADVECTION INTO THE MID-ATLANTIC. MOST IF NOT ALL PRECIPITATION SHOULD STAY SOUTH OF THE OUTLOOK AREA. CLOUDS AND LOW SUN ANGLE WILL LIMIT HEATING TODAY AND TEMPS WILL ONLY CLIMB INTO THE UPPER 30S TO AROUND 40 TODAY. MULTIPLE ROUNDS OF ENERGY WILL PASS OVER THE MID-ATLANTIC THROUGH TONIGHT. DUE TO LITTLE FORCING AS THE JET STREAM IS FURTHER SOUTH...DRY CONDITIONS ARE EXPECTED THROUGH TONIGHT. SUBSIDENCE BEHIND ANY VORT MAXES MAY LEAD TO SOME CLEARING. FCST MIN TEMPS SHOULD BE IN THE UPPER 20S TO LOW 30S IN URBAN AREAS. CLEARING MAY RESULT IN TEMPS DROPPING A FEW MORE DEGREES.
-- End Changed Discussion --
&& .SHORT TERM /SUNDAY THROUGH MONDAY/...
-- Changed Discussion --
HIGH PRESSURE EXTENDS FROM NEW ENGLAND DOWN INTO THE MID-ATLANTIC SUNDAY. MODELS SUGGEST A GOOD DEAL OF SUNSHINE WITH MAXIMA NEAR CLIMO. HIGH PRESSURE EDGES A LITTLE EAST SUNDAY NIGHT INTO MONDAY...WITH PRESSURE PATTERN SIGNALING SOME SEMBLANCE OF A WEDGE. AT THE SAME TIME...SOUTHERN STREAM SHORTWAVE ENERGY IS ALSO FORECAST TO MOVE NORTHEAST ON MONDAY. RESULT WILL BE INCREASING/THICKENING CLOUDS SUNDAY NIGHT BUT THINK ANY PRECIP WILL REMAIN TO THE SOUTH THROUGH DAYBREAK. TREND OF THE MODELS IS TO DELAY PRECIP A LITTLE LONGER DURING THE DAY MONDAY. LEANED TOWARD ECMWF/SREFS FOR TIMING. BUT IF PRECIP ARRIVES EARLY ENOUGH...MONDAY MORNING MAY SEE A WINTRY MIX OF PRECIP PARTICULARLY BLUE RIDGE WESTWARD. BULK OF THE PRECIP MONDAY AFTERNOON/EVENING APPEARS TO BE RAIN BUT A WINTRY MIX INCLUDING POTENTIAL ICING FROM FREEZING RAIN MAY LINGER ACROSS THE HIGHER ELEVATIONS OF THE POTOMAC HIGHLANDS INTO MONDAY EVENING.
-- End Changed Discussion --
&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
-- Changed Discussion --
SHORTWAVE EXITS LATE MONDAY NIGHT...BUT THE WEDGE REMAINS INTO TUESDAY AND WITH LOW LEVEL MOISTURE IN PLACE CHANCE OF RAIN OR DRIZZLE CONTINUES. ATTENTION THEN TURNS TO A DEEP/STRONG UPPER LEVEL TROUGH SENDING A COLD FRONT THROUGH LATE WEDNESDAY. DECENT LOW LEVEL JET AND PLUME OF MOISTURE ARE EXPECTED TO BE TRANSPORTED AHEAD OF THE FRONT ON WEDNESDAY...LEADING TO SHOWERS. MAXIMA ARE EXPECTED TO BE WARM FOR THIS TIME OF YEAR AND HAVE TRENDED MAXIMA NEAR 60 EAST OF THE BLUE RIDGE FOR WEDNESDAY. DYNAMIC SYSTEM MOVES AWAY WEDNESDAY NIGHT. TIGHT GRADIENT AND COLD ADVECTION BRING A WINDY AND COOLER CHRISTMAS DAY...ALTHOUGH MAXIMA MAY ACTUALLY STILL BE A FEW DEGREES ABOVE CLIMO.
-- End Changed Discussion --
&& .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
VFR CONDITIONS EXPECTED TODAY AND TONIGHT. CLOUDS WILL INCREASE FROM SW TO NE ACROSS THE TERMINALS TODAY. MID-HIGH LEVEL CIGS EXPECTED. -SN IS POSSIBLE BUT NOT LIKELY AT CHO THIS MORNING. NW WINDS AROUND 5 KTS EXPECTED TODAY AND TONIGHT. DEVELOPING WEDGE AND AREA OF LOW PRESSURE WILL LIKELY BRING SOME RAIN AND AT LEAST MVFR CONDITIONS MONDAY. IF PRECIP ARRIVES EARLY ENOUGH MONDAY MORNING...IT MAY BEGIN AS A MIX. IFR OR LOWER CONDITIONS ARE THEN EXPECTED MONDAY NIGHT INTO TUESDAY WITH WEDGE IN PLACE AND AREAS OF RAIN OR DRIZZLE. STRONG COLD FRONT FOLLOWS LATE WEDNESDAY WITH SHOWERS/POSSIBLY GUSTY WINDS.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
HIGH PRESSURE WILL PERSIST ACROSS THE WATERS TODAY AND TONIGHT. NW WINDS 5-10KTS ARE EXPECTED ON THE WATERS TODAY AND WEAKEN FURTHER INTO TONIGHT. HIGH PRESSURE OVER NEW ENGLAND ON SUNDAY MOVES OFFSHORE EARLY IN THE WEEK. SCA CONDITIONS ARE POSSIBLE IN SOUTHERLY FLOW AHEAD OF A COLD FRONT ON WEDNESDAY...THEN BEHIND THE FRONT FOR WEDNESDAY NIGHT AND THURSDAY.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BPP/HAS NEAR TERM...HAS SHORT TERM...BPP LONG TERM...BPP AVIATION...BPP/HAS MARINE...BPP/HAS

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.