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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 171901 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 301 PM EDT THU APR 17 2014 .SYNOPSIS... HIGH PRESSURE OVER NEW ENGLAND WILL STRETCH SOUTHWARD TOWARD THE MID-ATLANTIC COAST THROUGH THE REMAINDER OF THE WEEK. AN AREA OF LOW PRESSURE AND COLD FRONT MAY AFFECT THE AREA SATURDAY. A SECOND COLD FRONT LOOKS TO MOVE THROUGH THE REGION TUESDAY. && .NEAR TERM /THROUGH FRIDAY/...
-- Changed Discussion --
HIGH PRESSURE OVER MAINE CONTINUES TO EXTEND SOUTHWARD THROUGH THE MID-ATLANTIC STATES THIS AFTERNOON. THERE HAVE BEEN SOME HIGH CLOUDS STREAMING ACROSS THE CWA...AND ALSO A FEW STRATOCU ADVECTING WESTWARD INTO N/C MARYLAND. OTHERWISE...MOSTLY SUNNY SKIES HAVE PREVAILED UNDER A MODIFIED COOL AIR MASS. TONIGHT WILL BE DRY AND COOL AGAIN...ALTHOUGH PERHAPS NOT QUITE AS COOL AS LAST NIGHT UNDER A LIGHT EASTERLY FLOW REGIME. IT IS SOMEWHAT UNCERTAIN HOW MUCH LOW CLOUD COVER MAY PUSH WESTWARD FROM THE OCEAN. BEST CHANCE FOR STRATUS APPEARS TO BE IN SOUTHERN MARYLAND INTO THE NORTHERN VA PIEDMONT. THIS WOULD ALSO TEND TO KEEP TEMPERATURES A LITTLE HIGHER. BUT FURTHER NORTHWEST...MID 30S/LIGHT WINDS SUPPORTS A FROST ADVISORY IN THOSE COUNTIES EAST OF THE BLUE RIDGE THAT ARE IN THE OFFICIAL GROWING SEASON. THIS LASTS TIL 8 AM FRIDAY MORNING. HIGH PRESSURE BEGINS TO NUDGE A LITTLE EAST ON FRIDAY AS A WEAK COLD FRONT APPROACHES FROM THE WEST. WE/LL LIKELY HAVE MORE CLOUD COVER ON FRIDAY COMPARED TO TODAY...BUT FORECAST WILL BE DRY. MAXIMA SIMILAR OR SLIGHTLY ABOVE TODAY.
-- End Changed Discussion --
&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
NORTHERN AND SOUTHERN STREAM LOWS WILL SPLIT THE AREA OVER THE WEEKEND. IN THE NORTHERN STREAM...LOW PRESSURE NORTH OF THE GREAT LAKES WILL PRODUCE A WEAK COLD FRONT THAT WILL DETERIORATE AS IT MOVES OVER THE APPALACHIAN MOUNTAINS. THIS FRONT WILL BE DRY BY THE TIME IT REACHES OUR AREA SATURDAY MORNING...THOUGH IT COULD PROVIDE A BIT OF A REINFORCEMENT OF COOL AIR FOR THE DAY ON SATURDAY. THE FEATURE THAT WILL HAVE A STRONGER INFLUENCE ON THE MID ATLANTIC WEATHER WILL BE A SOUTHERN STREAM LOW THAT WILL CUT OFF FROM THE UPPER LEVEL FLOW OVER THE GULF STATES FRIDAY NIGHT AND MOVE INTO THE ATLANTIC OCEAN NEAR THE GA/FL BORDER EARLY SATURDAY MORNING. THE PRIMARY MODEL DIVERGENCE AT THIS TIME IS WITH THE TRACK OF THIS LOW AND THE SIZE OF THE PRECIPITATION SHIELD ASSOCIATED WITH IT. ECMWF AND NAM KEEP US DRY THROUGH HE WEEKEND WHILE THE GFS IS WETTER OVERALL...WITH PRECIPITATION COVERING THE SOUTHERN PORTIONS OF THE CWA THROUGH THE DAY ON SATURDAY. HAVE LEFT ANY CHANCE OF POPS OUT OF THE FORECAST GIVEN THAT THE GFS IS CLEARLY THE OUTLIER. DRY NORTHERLY FLOW WILL KEEP SKIES CLEAR FOR THE WEEKEND WITH CLOUD ASSOCIATED WITH THE LOW STAYING MOSTLY TO OUR SOUTH AND EAST. WITH THE LOW TO OUR SOUTH AND HIGH PRESSURE TO THE NORTH SOME COLD AIR WEDGING IS POSSIBLE OVER THE WEEKEND...BUT WITH NERLY 850 MB FLOW A STRONG CAD EVENT IS NOT EXPECTED...MOSTLY JUST WEAK COLD AIR ADVECTION. EXPECT HIGHS TO BE IN THE MID TO UPPER 60S SAT AND SUN THANKS TO PLENTY OF SUNSHINE. THE WEAK NORTHERLY FLOW WILL KEEP NIGHTS COLD...WITH SAT LOWS IN THE 30S AND SUNDAY LOWS NEAR 40.
-- End Changed Discussion --
&& .LONG TERM /MONDAY THROUGH THURSDAY/...
-- Changed Discussion --
AN AXIS OF HIGH PRESSURE WILL REMAIN ANCHORED ALONG THE EASTERN SEABOARD INTO EARLY NEXT WEEK AS AN AREA OF LOW PRESSURE DRIFTS OFF THE GA/FL COAST AND EAST TOWARDS BERMUDA...WELL SOUTH OF THE AREA. A GENERALLY LIGHT EASTERLY FLOW WILL PERSIST ACROSS THE AREA BETWEEN THESE TWO FEATURES. TEMPERATURES WILL BE NEAR NORMAL SUNDAY NIGHT INTO MONDAY NIGHT...WITH DAYTIME HIGHS AT OR ABOVE 70 FOR MOST OF THE AREA /WARMEST WEST AWAY FROM THE COOLER WATER/ AND OVERNIGHT LOWS IN THE 40S TO AROUND 50. THE LATEST GFS/ECMWF AND THEIR RESPECTIVE ENSEMBLE MEMBERS HAVE A COLD FRONT CROSSING THE AREA FROM WEST TO EAST ON TUESDAY WITH VARYING INTENSITY. THIS FRONT WILL BRING A CHANCE OF RAIN SHOWERS TO THE AREA...AND COULD BE ACCOMPANIED BY A FEW THUNDERSTORMS DEPENDING ON THE EXACT TIMING OF THE FRONTAL PASSAGE AND THE AMOUNT OF MOISTURE/INSTABILITY RETURN AHEAD OF THE FRONT. HIGH PRESSURE WILL BUILD TOWARDS THE AREA FROM THE NORTHERN PLAINS AND GREAT LAKES WITH BRIEFLY COOLER TEMPERATURES EXPECTED WEDNESDAY. TEMPERATURES LOOK TO START WARMING AGAIN BY NEXT THURSDAY AS THE HIGH PUSHES TO THE EAST.
-- End Changed Discussion --
&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
PREVAILING VFR CONDITIONS THROUGH FRIDAY UNDER LIGHT EAST FLOW. SREFS SUGGESTS THE POSSIBILITY OF LOWER CIGS DEVELOPING LATE TONIGHT/EARLY FRIDAY. CONFIDENCE IS ON THE LOW SIDE...BUT GIVEN EASTERLY FLOW OFF THE OCEAN THIS CAN/T BE RULED OUT. OUTLOOK...VFR CONDITIONS IN EASTERLY FLOW OF 5 TO 10 KNOTS IS FORECAST THROUGH EARLY NEXT WEEK.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
WINDS HAVE ABATED A LITTLE THIS AFTERNOON BUT ARE FORECAST TO INCREASE AGAIN THIS EVENING IN E/SE FLOW. SCA IS IN EFFECT FOR PARTS OF THE BAY INTO THE LOWER TIDAL POTOMAC INTO TONIGHT. CURRENT FORECASTS ARE FOR WINDS UNDER SCA CRITERIA FRIDAY. A SMALL CRAFT ADVISORY MAY BE NECESSARY FOR THE LOWER MARYLAND CHESAPEAKE BAY SUNDAY NIGHT AS LOW PRESSURE MOVES AWAY FROM THE MID ATLANTIC SEABOARD. SUB-SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED IN GENERALLY LIGHT EASTERLY FLOW AROUND HIGH PRESSURE SUNDAY NIGHT THROUGH MONDAY NIGHT...THEN MODEST SOUTHERLY AHEAD OF A COLD FRONT BY TUESDAY. SMALL CRAFT ADVISORY LEVEL WINDS ARE POSSIBLE WEDNESDAY IN GUSTY NORTHWEST FLOW BEHIND DEPARTING COLD FRONT AND AHEAD OF APPROACHING HIGH PRESSURE.
-- End Changed Discussion --
&& .CLIMATE...
-- Changed Discussion --
THIS MORNING WAS ANOTHER ABNORMALLY COLD MORNING FOR THIS TIME OF YEAR...WITH MUCH OF THE AREA EXPERIENCING LOW TEMPERATURES AT OR BELOW FREEZING /AROUND 10 DEGREES BELOW NORMAL/. DESPITE THE COLD...NO RECORD MINIMUM TEMPERATURES WERE OBSERVED. BELOW IS A LIST OF WHAT THE RECORD LOWS ARE FOR TODAY COMPARED TO THE PRELIMINARY LOW TEMPERATURES THAT WERE OBSERVED THIS MORNING. SITE...RECORD........LOW TEMP... DCA....26 F (1875)...39 F....... BWI....26 F (1962)...30 F....... IAD....27 F (1983)...28 F.......
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...FROST ADVISORY FROM 2 AM TO 8 AM EDT FRIDAY FOR MDZ004>007- 009>011. VA...FROST ADVISORY FROM 2 AM TO 8 AM EDT FRIDAY FOR VAZ036>040-042- 050-051-501-502. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 AM EDT FRIDAY FOR ANZ532>534-537- 540-541-543. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 3 AM EDT FRIDAY FOR ANZ531-536-538-539-542.
-- End Changed Discussion --
&& $$ SYNOPSIS...BPP NEAR TERM...BPP SHORT TERM...CEB LONG TERM...DFH AVIATION...BPP/CEB/DFH MARINE...BPP/CEB/DFH

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