Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 231407 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1007 AM EDT MON MAR 23 2015 .SYNOPSIS...
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HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THIS AFTERNOON. AN UPPER LEVEL DISTURBANCE WILL PASS THROUGH THE AREA TONIGHT AND HIGH PRESSURE WILL RETURN FOR TUESDAY. THE HIGH WILL MOVE OFF THE COAST WEDNESDAY AND A COLD FRONT IS EXPECTED TO PASS THROUGH LATE THURSDAY INTO THURSDAY NIGHT. CANADIAN HIGH PRESSURE WILL RETURN FOR FRIDAY INTO THE WEEKEND.
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&& .NEAR TERM /THROUGH TUESDAY/...
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SURFACE HIGH PRESSURE WILL BUILD OVER NEW ENGLAND TODAY AND THE RIDGE AXIS WILL EXTEND SOUTH INTO THE MID-ATLANTIC. AN UPPER-LEVEL DISTURBANCE IN THE SOUTHERN BRANCH OF THE JET WILL MOVE OFF THE SOUTHEAST COAST THIS AFTERNOON WHILE ANOTHER UPPER-LEVEL DISTURBANCE IN THE NORTHERN BRANCH OF THE JET TRACKS THROUGH THE OHIO VALLEY. THERE WILL BE SOME HIGH AND MID-LEVEL CLOUDS THAT MOVE INTO THE AREA AHEAD OF THE UPPER-LEVEL DISTURBANCE THAT IS MOVING INTO THE OHIO VALLEY. HOWEVER...THE CLOUD DECK SHOULD BE THIN AND THAT WILL ALLOW FOR MOSTLY TO PARTLY SUNNY SKIES. WILL CONTINUE TO LEAN TOWARD THE WARMER GUIDANCE WITH THE FORECAST FOR MAX TEMPS...BUT TEMPS WILL REMAIN SEVERAL DEGREES BELOW CLIMO. THE UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION TONIGHT. THIS SYSTEM WILL WEAKEN AS IT IS MOVING THROUGH OUR AREA...BUT IT WILL BACK THE LOW-LEVEL FLOW TO THE SOUTHWEST WHICH WILL CAUSE OVERRUNNING. CLOUDS WILL INCREASE THIS EVENING AND THERE IS A CHANCE FOR SNOW SHOWERS TO AFFECT THE AREA LATE THIS EVENING AND OVERNIGHT. THE BEST CHANCE FOR ACCUMULATING SNOW WILL BE ALONG AND WEST OF THE ALLEGHENY FRONT WHERE AN UPSLOPE COMPONENT TO THE LOW-LEVEL FLOW WILL ENHANCE THE THREAT FOR SNOW SHOWERS. HOWEVER...SNOW MAY COAT THE GROUND EAST OF THE MOUNTAINS AS WELL. THE BEST CHANCE FOR A COATING OF SNOW IS ACROSS THE EASTERN PANHANDLE OF WEST VIRGINIA...NORTHERN SHENANDOAH VALLEY AND NORTH-CENTRAL MARYLAND WHERE LIFT WITH THE UPPER-LEVEL DISTURBANCE HAS THE BEST CHANCE TO COMBINE OVERRUNNING. SNOW SHOWERS MAY SPREAD INTO THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS TOWARD MORNING...AND A COATING OF SNOW IS POSSIBLE. ALTHOUGH THE PRECIPITATION AMOUNTS WILL BE LIGHT...THE TIMING COMBINED WITH THE FACT THAT TEMPERATURES WILL BE BELOW FREEZING SUGGESTS THAT THE MORNING RUSH HOUR MAY BE IMPACTED TUESDAY. SNOW SHOWERS MAY CONTINUE INTO TUESDAY MORNING...BUT THE DISTURBANCE WILL MOVE OFF THE COAST BY MIDDAY TUESDAY. HIGH 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/... 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. && .LONG TERM /THURSDAY THROUGH SUNDAY/... 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. && .AVIATION /14Z MONDAY THROUGH FRIDAY/...
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VFR CONDITIONS EXPECTED TODAY. A DISTURBANCE WILL BRING THE CHANCE FOR -SN LATE TONIGHT INTO TUESDAY MORNING. THE BEST CHANCE FOR -SN WILL BE ACROSS KMRB...AND POSSIBLY INTO KIAD...KDCA...KBWI AND KMTN. 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 THROUGH THIS AFTERNOON AND WINDS WILL CONTINUE TO DIMINISH. THE SCA CONTINUES UNTIL 1 PM THIS AFTERNOON. HOWEVER...THAT MAY BE ABLE TO BE CANCELLED EARLIER AS THE GRADIENT WEAKENS. WINDS SHOULD REMAIN BELOW SCA CRITERIA THROUGH TUESDAY WITH HIGH PRESSURE IN CONTROL. 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... 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. && $$ SYNOPSIS...HAS NEAR TERM...BJL/HAS SHORT TERM...KS LONG TERM...KS/KLW AVIATION...HAS/KS/KLW MARINE...HAS/KS/KLW

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