Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 230735 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 335 AM EDT MON MAR 23 2015 .SYNOPSIS...
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HIGH PRESSURE WILL BUILD OVERHEAD THROUGH TUESDAY BEFORE MOVING OFF THE COAST WEDNESDAY. AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE REGION TONIGHT. A COLD FRONT WILL CROSS THE AREA THURSDAY. CANADIAN HIGH PRESSURE WILL RETURN FOR FRIDAY INTO THE WEEKEND. HIGH PRESSURE WILL RETURN FOR LATE IN THE WEEK.
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&& .NEAR TERM /THROUGH TUESDAY/...
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AN UPPER LEVEL TROUGH OVER NEW ENGLAND WILL MOVE OFF THE EAST COAST THIS MORNING WHILE HIGH PRESSURE MOVES INTO THE REGION ONCE AGAIN. NRLY WINDS WILL CONTINUE TODAY RESULTING IN BELOW NORMAL TEMPS FOR THIS WEEK IN MARCH. LOW PRESSURE ACROSS THE SE US WILL MOVE OFF THE COAST THIS MORNING AND MID-HIGH LEVEL CLOUDS WILL FOLLOW SUIT AND MOVE OFF THE COAST BY MIDDAY. HIGH PRESSURE WILL WEDGE DOWN THE MID- ATLANTIC THIS AFTERNOON. ONSHORE FLOW ACROSS CENTRAL VA WILL RESULT IN CLOUDS BANKING UP AGAINST THE APPALACHIAN MTNS. CLOUDY CONDITIONS ARE EXPECTED ACROSS THE VA HIGHLANDS AND SHENANDOAH VALLEY TODAY. A SHORTWAVE TROUGH WILL TRACK SOUTHEASTWARD FROM THE NRN PLAINS TO THE OHIO VALLEY TODAY. MOISTURE IS ACCOMPANIED WITH THIS WAVE AND EXPECTED TO REACH THE ALLEGHENY FRONT TONIGHT. AS TEMPS DROP TONIGHT...SNOW SHOWERS ARE EXPECTED ACROSS THE WESTERN SLOPES OF THE ALLEGHENY FRONT THROUGH TUESDAY MORNING. LESS THAN AN INCH OF SNOW IS EXPECTED IN THIS AREA. THE WAVE WILL MOVE EASTWARD WHILE OVERRUNING TAKES PLACE AND SNOW SHOWERS ARE POSSIBLE EAST OF THE MTNS. DETERMINISTIC RUNS SHOW LIGHT QPF AS LIFT MOVES EASTWARD INTO THE PANHANDLE OF WV AND NRN MD/VA BY TUESDAY MORNING. FCST SOUNDINGS SHOW SATURATION IN THE MID-LEVELS BUT IT IS BELOW THE SGZ. DRY LOW LEVELS ARE EXPECTED AS WELL AND THEREFORE LITTLE TO NO ACCUMULATION IS EXPECTED EAST OF THE MTNS. EXPECTING SMALL FLAKES OR PLATES/COLUMNS/NEEDLES INSTEAD OF DENTRITES EAST OF THE MTNS AND THEREFORE SNOW WILL BE HARD TO ACCUMULATE. QUESTION EXISTS HOW FAR EAST THE SNOW SHOWERS WILL TRAVEL AND THE COVERAGE FOR THE TUESDAY MORNING RUSH. AT THIS TIME...FLURRIES AND ISO-SCT SNOW SHOWERS CANNOT BE RULED OUT ACROSS I-95 TUESDAY MORNING. THE WAVE WILL MOVE OFF THE COAST BY MIDDAY TUESDAY. HIGHER PRESSURE MOVES INTO THE REGION TUESDAY AND NRLY WINDS WILL RESULT IN BELOW NORMAL TEMPS AGAIN. SUNSHINE IS EXPECTED TOWARDS AFTERNOON TUESDAY.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
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HIGH PRESSURE WILL BE OVER THE EASTERN SEABOARD EARLY TUESDAY NIGHT...AND IS EXPECTED TO MIGRATE OFFSHORE BY WEDNESDAY MORNING. WELL-ORGANIZED LOW PRESSURE WILL MOVE MOVE FROM THE MISSISSIPPI VALLEY INTO THE GREAT LAKES. 00Z GFS SOMEWHAT MORE AGGRESSIVE THAN THE 00Z NAM OR ECMWF IN EXTENDING A WARM FRONT EAST OF THE LOW ACROSS TO THE MID-ATLANTIC...WHICH COULD RESULT IN OVERRUNNING LIGHT PRECIPITATION OVER PORTIONS OF THE FORECAST AREA. GFS BUFKIT SOUNDINGS ARE KEEPING TEMPS JUST ABOVE FREEZING IN MOST LOCATIONS...BUT WILL GO WITH POTENTIAL FOR A RAIN OR SNOW IN ANY AREAS THAT MAY GET PRECIPITATION LATE TUESDAY NIGHT. LOW TEMPS GENERALLY IN THE LOW TO MID 30S. RETURN FLOW WILL BE IN PLACE WEDNESDAY. MOISTURE RETURN SHOULD RESULT IN MOSTLY CLOUDY SKIES AND MAYBE A FEW SHOWERS. CLOUD COVER WILL CAP HIGH TEMPERATURES IN THE 50S. COLD FRONT MOVES INTO THE OHIO VALLEY WEDNESDAY NIGHT...WITH THE MID- ATLANTIC REMAINING IN MOIST RETURN FLOW. SOME SHOWERS POSSIBLE AGAIN...BUT WITH ONLY MODERATE CONFIDENCE WILL KEEP POPS HELD TO CHANCE. ONGOING CLOUD COVER AND WARM ADVECTION WILL KEEP TEMPS FROM DROPPING MUCH COMPARED TO THE DAYTIME HOURS...WITH LOWS MAINLY IN THE UPPER 40S TO LOWER 50S.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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COLD FRONT WILL SWEEP ACROSS THE AREA THURSDAY THROUGH THURSDAY EVENING. ONGOING CLOUD COVER WILL PROBABLY THE LIMITING FACTOR REGARDING THE AMOUNT OF HEATING AND INSTABILITY THAT DEVELOPS AHEAD OF THE FRONT...BUT AT THE MOMENT HIGH TEMPS ARE FCST TO REACH THE UPPER 60S AND LOWER 70S WITH DEW POINTS IN THE UPPER 50S AND LOW 60S. SHOWERS WILL BE LIKELY WITH THE FRONT...AND CONTINUED SLIGHT CHANCE OF TSTMS. COOLER AIR RETURNS FRIDAY. POTENTIAL FOR POST- FRONTAL UPSLOPE PRECIPITATION IN THE HIGHLANDS. HIGHS GENERALLY IN THE 40S AND 50S. SOME LIGHT RAIN OR SNOW POSSIBLE FRIDAY NIGHT INTO EARLY SATURDAY DUE TO AN UPPER TROUGH. BELOW NORMAL TEMPERATURES CONTINUE THROUGH THE WEEKEND.
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/...
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VFR CONDITIONS EXPECTED TODAY. A DISTURBANCE WILL BRING THE CHANCE FOR -SN LATE TONIGHT INTO TUESDAY MORNING. -SN MAY REDUCE VSBYS IF THEY REACH A TERMINAL BUT AT THIS TIME COVERAGE AND CONFIDENCE IS LOW AND THEREFORE VFR CONDITIONS ARE EXPECTED. PERIODIC SUB-VFR POSSIBLE TUESDAY NIGHT THROUGH THURSDAY NIGHT WITH OCNL SHRA. SLY WINDS AROUND 10KT...WITH SOME DAYTIME GUSTS PSBL WED. A POTENT COLD FRONT WILL MOVE THROUGH THURSDAY...WITH SHRA LIKELY AND A PSBL TSTM IN THE AFTN OR EVENING. S-SW WINDS WITH SOME PSBL GUSTS 15-20KTS. VFR LIKELY FRIDAY WITH NW WINDS.
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&& .MARINE...
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HIGH PRESSURE WILL MOVE ACROSS THE WATERS TODAY. A SURGE IS EXPECTED TO MOVE DOWN THE BAY THIS MORNING. AT THIS TIME...WINDS HAVE BEEN BELOW 18KTS BUT MIXING SHOULD INCREASE THIS MORNING AND THEREFORE SCA IS IN EFFECT. WINDS WILL SUBSIDE THIS AFTERNOON AND CONTINUE THROUGH TUESDAY. SCA PSBL WEDNESDAY WITH SOUTHERLY FLOW ACROSS THE WATERS. BETTER CHANCE OF SCA THURSDAY WITH STRONGER S-SW WINDS AHEAD OF A COLD FRONT. SHOWERS AND A PSBL TSTM THURSDAY OR THURSDAY EVENING WITH THE COLD FRONT. WINDS SHIFT TO THE NW FRIDAY BEHIND THE FRONT.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR ANZ530>534-537-539>541-543.
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&& $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...KS LONG TERM...KS AVIATION...HAS/KS MARINE...HAS/KS

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