Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 300740 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 340 AM EDT THU APR 30 2015 .SYNOPSIS... LOW PRESSURE WILL IMPACT THE AREA TODAY THROUGH TONIGHT BEFORE MOVING OFFSHORE FRIDAY. HIGH PRESSURE WILL BUILD OVERHEAD DURING THE WEEKEND BEFORE SHIFTING TO THE SOUTH EARLY NEXT WEEK. A COLD FRONT MAY IMPACT THE AREA DURING THE MIDDLE PORTION OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... THIS MORNING...SATELLITE IMAGERY SHOWS CLOUD COVER MAINLY WEST OF THE BLUE RIDGE...AND ALSO SPREADING NORTHWARD OVER THE EASTERN THIRD OF THE FORECAST AREA. RADAR INDICATES ISOLATED -SHRA SLOWLY MOVING NORTHWARD THROUGH THE HIGHLANDS. A CLOSED LOW OVER LAKE MICHIGAN WILL DIVE SOUTHWARD INTO THE OHIO VALLEY TODAY...AND A COASTAL SFC LOW WILL BE DEVELOPING OFF THE CAROLINA COAST. HERE AT HOME...WEAK DISTURBANCES WILL CONTINUE TO AFFECT THE AREA ALONG WITH A GRADUAL INCREASE IN MOISTURE THROUGH THE ATMOSPHERIC COLUMN. WITH DAYTIME HEATING...EXPECT AN INCREASE IN SHRA ACTIVITY...AND ENOUGH INSTABILITY WILL EXIST FOR SOME TSRA POTENTIAL AS WELL. WOULD NOT AT ALL BE SURPRISED TO SEE SOME SMALL HAIL IN THE CONVECTION THIS AFTERNOON...BUT NOT EXPECTING ANY SEVERE WEATHER AT ALL. POPS WERE TAPERED FROM CATEGORICAL SW TO LOW CHANCE NE BASED ON LOCATION OF SFC/ALOFT FEATURES AND MOISTURE PROFILE. EAST OF THE BLUE RIDGE...HIGHS COULD TOP 70 AGAIN...BUT THAT IS HIGHLY DEPENDENT ON CLOUD COVER. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... OUR BEST CHANCE FOR RAIN IS TONIGHT AS THE UPPER LOW KICKS EAST FROM THE OHIO VALLEY TOWARD THE OUTER BANKS. OVERALL RAIN SHOULD REMAIN FAIRLY LIGHT...AND PWATS DO NOT GET ALL THAT HIGH...BUT UPSLOPE FLOW AT H9/H8...NEAR THE SURFACE AT HIGHER ELEVATIONS...WILL AID IN POTENTIALLY HEAVIER PRECIPITATION IN THESE FAVORED REGIONS. NOT CONSIDERING A FLOOD WATCH AT THIS TIME...BUT LOCALIZED UPSLOPE HEAVY RAIN IS POSSIBLE. AFTER MIDNIGHT AND INTO FRIDAY...THE UPPER LOW PUSHES OFFSHORE... WITH WINDS BECOMING UNIDIRECTIONALLY NORTH. THIS WILL LIMIT MOISTURE AND POPS WERE TRENDED SIMILARLY...HIGHEST SOUTH AND LOWEST NORTH. TEMPS WILL BE A BIT COOLER WITH HIGHS ONLY 55 TO 65. FRIDAY NIGHT LOOKS DRY. THE HIGHLANDS COULD DROP INTO THE UPPER 30S AS WINDS DECOUPLE. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AN UPPER-LEVEL TROUGH WILL REMAIN OVERHEAD SATURDAY WHILE SURFACE HIGH PRESSURE APPROACHES FROM THE WEST. MAX TEMPS WILL BE CLOSER TO CLIMO DUE TO MORE SUNSHINE. HOWEVER...WITH THE COOLER AIR ALOFT STILL IN PLACE...THE SUNSHINE WILL LEAD TO LIMITED INSTABILITY DURING THE AFTERNOON AND EVENING HOURS. THIS WILL CAUSE A BKN CU DECK TO DEVELOP AND THERE MAY BE ENOUGH INSTABILITY FOR A FEW SHOWERS ACROSS THE AREA. MOISTURE WILL BE LIMITED AND FORCING WILL BE WEAK SO MOST OF THE TIME WILL BE DRY AND COVERAGE OF SHOWERS WOULD BE SCATTERED AT BEST. THE HIGH WILL BUILD OVERHEAD SATURDAY NIGHT. LIGHT WINDS AND CLEARING SKIES MAY RESULT IN CHILLY CONDITIONS SATURDAY NIGHT WITH MIN TEMPS IN THE 40S ACROSS MANY LOCATIONS AND EVEN 30S IN PORTIONS OF THE POTOMAC HIGHLANDS. MIN TEMPS WILL HOLD IN THE 50S FOR DOWNTOWN WASHINGTON AND BALTIMORE. THE UPPER-LEVEL TROUGH WILL BEGIN TO SLIDE TO THE EAST SUNDAY AND HIGH PRESSURE OVERHEAD WILL BEGIN TO SLIDE TO THE SOUTH. A RETURN FLOW AROUND THE HIGH ALONG WITH SUNSHINE AND RISING HEIGHTS WILL ALLOW FOR WARMER CONDITIONS DURING THE AFTERNOON. THE WARMING TREND WILL CONTINUE FOR MONDAY AND TUESDAY DUE TO A SOUTHWEST FLOW AROUND HIGH PRESSURE CENTERED TO OUR SOUTH. MAX TEMPS IN THE 80S ARE LIKELY FOR MANY LOCATIONS. A COLD FRONT WILL DROP SOUTH TOWARD THE REGION LATE TUESDAY AND IT WILL STALL OUT NEARBY FOR THE MIDDLE PORTION OF NEXT WEEK. UNSETTLED CONDITIONS ARE POSSIBLE DURING THIS TIME. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... A LOT OF THE MOISTURE TODAY IS ALOFT /5 KFT AND HIGHER/ SO EVEN THOUGH SHRA AND A FEW TSRA ARE EXPECTED...LOW CIGS ARE NOT PARTICULARLY LIKELY DURING THE DAY TODAY. LOW LEVEL MOISTURE DOES INCREASE TONIGHT...AND THUS CIGS SHOULD LOWER TO AT LEAST MVFR AFTER MIDNIGHT. IFR CIGS ARE POSSIBLE AROUND SUNRISE BUT DID NOT INCLUDE THEM IN THE TAF YET. VSBY RESTRICTIONS IN SHRA SHOULD BE MVFR AT WORST. CONDITIONS VFR BY SHORTLY AFTER DAYBREAK FRIDAY AS LOW LEVELS DRY. WINDS WILL GENERALLY BE LESS THAN 10 KT TODAY...INCREASING TO 10 TO 15 KT THROUGH THE REST OF THE TAF PERIOD...BECOMING LIGHT FRIDAY NIGHT. VFR CONDITIONS ARE EXPECTED MOST OF THE TIME SATURDAY THROUGH MONDAY. A FEW SHOWERS ARE POSSIBLE SATURDAY AFTERNOON AND EVENING...BUT MOST OF THE TIME WILL BE DRY. && .MARINE... WINDS FAIRLY LIGHT AND VARIABLE THROUGH THIS MORNING...BUT GRADUALLY INCREASING THROUGH THE DAY. SHOULD REMAIN BELOW SCA LEVEL THOUGH. SCA ALREADY IN EFFECT STARTING THIS EVENING AS LOW PRESSURE STRENGTHENS OFFSHORE. GUSTS TO 20 KTS LOOK LIKELY TONIGHT INTO EARLY FRIDAY BEFORE WINDS GRADUALLY DECREASE. SCA WAS EXTENDED TO NOON FRIDAY IN THE UPPER BAY/UPPER POTOMAC...AND THROUGH 6 PM FRIDAY ELSEWHERE. THE SOUTHERN BAY COULD CONTINUE TO GUST FRIDAY EVENING...SO THE SCA MAY HAVE TO BE FURTHER EXTENDED BY FUTURE SHIFTS. HIGH PRESSURE WILL BUILD TOWARD THE WATERS SATURDAY BEFORE SETTLING OVERHEAD SATURDAY NIGHT. A NORTHERLY FLOW SATURDAY WILL BECOME LIGHT AND VARIABLE SATURDAY NIGHT. HIGH PRESSURE WILL BUILD TO THE SOUTH FOR SUNDAY THROUGH EARLY NEXT WEEK. SOUTHERLY WINDS ARE EXPECTED DURING THIS TIME. WIND GUSTS MAY APPROACH SCA CRITERIA FOR PORTIONS OF THE WATERS MONDAY NIGHT AND TUESDAY. && .TIDES/COASTAL FLOODING... TIDAL ANOMALIES ARE AROUND ONE-HALF TO THREE QUARTERS OF A FOOT ABOVE NORMAL EARLY THIS MORNING. WINDS WILL REMAIN LIGHT TODAY SO ANOMALIES WILL NOT CHANGE MUCH. THEREFORE THE HIGHEST WATER LEVELS ARE EXPECTED WITH THE TIDE CYCLE EARLY THIS MORNING SINCE THAT IS THE HIGHER OF THE TWO ASTRONOMICAL NORMS. HOWEVER...WATER LEVELS ARE EXPECTED TO REMAIN BELOW MINOR FLOODING THRESHOLDS. A NORTHEAST WIND WILL INCREASE TONIGHT...THIS WILL KEEP WATER LEVELS ELEVATED BUT THE NORTHERLY COMPONENT WILL LIKELY KEEP ANOMALIES LOW ENOUGH SO WATER LEVELS REMAIN BELOW MINOR FLOODING THRESHOLDS WITH THE HIGH TIDE CYCLE LATE TONIGHT INTO FRIDAY MORNING. && .EQUIPMENT... THERE WAS NO 00Z KIAD RAOB DUE TO EQUIPMENT MALFUNCTION. TECHNICIANS WILL BE INVESTIGATING THE ISSUE PRIOR TO THE 12Z LAUNCH. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT FRIDAY FOR ANZ530>534-536>543. && $$ SYNOPSIS...BJL NEAR TERM...JCE SHORT TERM...JCE LONG TERM...BJL AVIATION...JCE/BJL MARINE...JCE/BJL TIDES/COASTAL FLOODING...BJL EQUIPMENT...BJL

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