Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 241433 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1033 AM EDT THU JUL 24 2014 .SYNOPSIS... A COLD FRONT WILL SLOWLY PASS THROUGH CENTRAL AND SOUTHERN VIRGINIA TODAY. HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT THROUGH FRIDAY BEFORE MOVING OFF THE COAST DURING THE WEEKEND. A COLD FRONT WILL PASS THROUGH THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AN UPPER LEVEL TROUGH AXIS WILL CONTINUE TO APPROACH THE MID ATLANTIC THIS MORNING. A SFC COLD FRONT HAS MOVED INTO SOUTHERN VA WHERE HEAVY SHOWERS AND STRONG CONVECTION ARE TAKING PLACE. LIGHT NRLY WINDS BEHIND THE FRONT HAVE LED TO A SLOW DRYING PROCESS AT THE SFC. DEWPTS RANGE FROM THE LOW 60S NEAR THE MASON DIXON LINE TO THE 70S NEAR CHO. AHEAD OF THE TROUGH AXIS AND IN THE W-SW FLOW ALOFT...A DISTURBANCE WILL MOVE OFF THE EAST COAST THIS MORNING AND SUBSIDENCE BEHIND THIS FEATURE HAS LED TO CLOUDS BREAKING ACROSS WV/SW VA. THIS WILL INCREASE INSTABILITY IN THIS AREA SINCE DEWPTS ARE STILL HIGH. PER THE 12Z IAD RAOB AND RNK RAOB...INSTABILITY IS PRESENT AND INCREASES TO THE SOUTH WITH HIGHER DEWPTS. A FEW SHOWERS W ISOLATED THUNDERSTORMS ARE EXPECTED IN THE CENTRAL FOOTHILLS AND SHENANDOAH VALLEY THROUGH THE AFTERNOON. FURTHER NORTH...NRLY WINDS WILL SLOWLY ADVECT DRY COOLER AIR INTO THE REGION AND RAIN CHANCES WILL TAPER FROM NORTH TO SOUTH TODAY AHEAD OF THE TROUGH AXIS. PREVIOUS DISCUSSION... TEMPS WILL STILL MAKE IT INTO THE L-M80S ACROSS THE AREA FOR DAYTIME HIGHS...BUT DEWPOINTS WILL HOVER IN THE M50S OR LOWER THIS AFTN WHICH IS A NOTICEABLY LESS HUMID FEEL TO THE AIR THAN THE PAST COUPLE OF DAYS. THE NEAR-10 DEG DROP IN DEWPOINTS WILL REFLECT IN THE OVERNIGHT LOWS AS WELL ON THU NIGHT/FRI MRNG. TEMPS ACROSS THE NRN HALF WILL DROP TO THE L60S AND SOME U50S...WHILE THE I-95 CORRIDOR AND AREAS SOUTH/EAST WILL SEE LOWS IN THE L-M60S. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... A WEAK UPPER-LEVEL TROUGH WILL REMAIN OVERHEAD FRIDAY. HOWEVER...SURFACE HIGH PRESSURE WILL ALSO BE OVERHEAD SO DRY CONDITIONS ARE EXPECTED ALONG WITH SUNSHINE. A SCT/BKN CU DECK WILL DEVELOP DURING THE AFTERNOON. MAX TEMPS WILL RANGE FROM THE UPPER 60S AND LOWER 70S IN THE MOUNTAINS TO THE LOWER AND MIDDLE 80S ACROSS MOST OTHER LOCATIONS. DEWPOINTS IN THE 50S AND 60S WILL ALSO MAKE IT FEEL NOTICEABLY LESS HUMID COMPARED TO RECENT DAYS. HIGH PRESSURE WILL REMAIN OVERHEAD FRIDAY NIGHT...BRINGING DRY AND COMFORTABLE CONDITIONS. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... HIGH PRESSURE WILL MOVE OFF THE COAST SATURDAY AND A RETURN SOUTHERLY FLOW WILL USHER IN WARMER AND A BIT MORE HUMID CONDITIONS. THE INCREASED HEAT AND HUMIDITY MAY LEAD TO A COUPLE SHOWERS AND THUNDERSTORMS...BUT COVERAGE SHOULD REMAIN ISOLATED TO WIDELY SCATTERED DUE TO THE LACK OF A STRONG LIFTING MECHANISM. A POTENT COLD FRONT WILL MOVE THROUGH THE GREAT LAKES SUNDAY AND THIS WILL CARVE OUT A TROUGH OF LOW PRESSURE BOTH AT THE UPPER- LEVELS AND LOWER-LEVELS OF THE ATMOSPHERE ACROSS OUR AREA. A SOUTHERLY FLOW AROUND HIGH PRESSURE OFF THE ATLANTIC WILL CONTINUE TO USHER IN WARM AND HUMID CONDITIONS. THE INCREASED FORCING ALONG WITH THE HEAT AND HUMIDITY WILL LEAD TO A BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL PASS THROUGH THE AREA MONDAY...BRINGING THE CHANCE FOR MORE SHOWERS AND THUNDERSTORMS. NOTICEABLY COOLER AND DRIER CONDITIONS ARE EXPECTED BEHIND THE FRONT FOR THE MIDDLE PORTION OF NEXT WEEK. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... A COLD FRONT SAGGING SOUTH ACROSS THE AREA WILL SLOWLY USHER-IN A STIFF NW-NLY BREEZE LATER THIS MRNG. MVFR/VFR CONDITIONS EXPECTED THIS MORNING AS CIGS CONTINUE TO LIFT. THIS WILL AFFECT AREAS ALONG THE I-95 CORRIDOR AND EAST W/ A GENERAL N WIND NEAR 10KT. PRECIP WILL DECREASE THROUGHOUT THE DAY AND INTO TONIGHT W/ CLEARING SKIES AND LIGHT WINDS TOWARD FRI MRNG. HIGH PRESSURE WILL BRING VFR CONDITIONS FOR FRIDAY THROUGH FRIDAY EVENING. PATCHY FOG IS EXPECTED LATE FRIDAY NIGHT INTO SATURDAY MORNING. A SOUTHERLY FLOW WILL DEVELOP FOR SATURDAY AND SUNDAY AS HIGH PRESSURE MOVES OFF THE COAST. THE INCREASED MOISTURE FROM THE SOUTHERLY FLOW WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. THUNDERSTORMS WILL BE MORE WIDESPREAD IN COVERAGE SUNDAY. A COLD FRONT FRONT WILL PASS THROUGH THE TERMINALS MONDAY...BRINGING THE CHANCE FOR MORE SHOWERS AND THUNDERSTORMS. && .MARINE... SHOWERS ARE EXPECTED FROM ANNAPOLIS AND DC SOUTH THIS MORNING AND EARLY AFTERNOON AS A COLD FRONT SOUTH OF THE WATERS MOVES FURTHER SOUTH. NRLY WINDS WILL INCREASE TO 10-15KT BY THIS AFTERNOON AS WIND CHANNELS DOWN THE BAY. A BRIEF RESPITE AND THEN SOME MORE NLY CHANNELING OVERNIGHT...BUT EXPECTED TO BE NEAR BUT BELOW SCA RANGE. A SCA ADVISORY IS IN EFFECT FOR THE MD CHESAPEAKE BAY SOUTH OF POOLES ISLAND AND LOWER TIDAL POTOMAC LATE TONIGHT THROUGH FRIDAY MORNING. HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY INTO FRIDAY NIGHT. THE HIGH WILL MOVE OFF THE COAST SATURDAY AND SUNDAY...ALLOWING FOR A SOUTHERLY FLOW TO DEVELOP. SOUTHERLY WINDS MAY GUST PAST SCA CRITERIA FOR PORTIONS OF THE WATERS SATURDAY AFTERNOON THROUGH SUNDAY MORNING. A POTENT COLD FRONT WILL PASS THROUGH THE WATERS EARLY NEXT WEEK. SHOWERS AND THUNDERSTORMS ARE POSSIBLE SATURDAY THROUGH MONDAY. AS OF NOW IT APPEARS THAT THE MOST WIDESPREAD COVERAGE IN THUNDERSTORMS WILL BE SUNDAY INTO SUNDAY NIGHT...BUT CERTAINTY REMAINS LOW THIS FAR OUT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 8 AM EDT FRIDAY FOR ANZ531>534-537-539>543. && $$ SYNOPSIS...BJL NEAR TERM...HAS/GMS SHORT TERM...BJL LONG TERM...BJL AVIATION...BJL/GMS MARINE...BJL/GMS

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