Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 010800 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 400 AM EDT WED JUL 1 2015 .SYNOPSIS... A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST TODAY. THE FRONT WILL STALL OUT IN CENTRAL VIRGINIA TONIGHT. THE FRONT WILL LINGER OVER THE REGION THROUGH THE WEEKEND...WITH SEVERAL WAVES OF LOW PRESSURE MOVING EAST ALONG IT. && .NEAR TERM /THROUGH TONIGHT/... STRONG STORMS ASSOCIATED WITH POTENT SHORTWAVE TROUGH ARE MOVING OFF TO THE EAST. WILL KEEP AN EYE OUT FOR A LINGERING SHOWER ACROSS NORTHERN AREAS THROUGH THIS MORNING...BUT OTHERWISE SHOULD BE MAINLY DRY. LOW PRESSURE IS LIFTING OUT OF THE GREAT LAKES...WITH REAL PUSH OF DRIER AIR WELL TO OUR NW. LOOSELY DEFINED FRONTAL ZONE SAGS SOUTH TODAY. NOT A LOT OF FORCING IN PLACE...AND INSTBY LOOKS TO BE RATHER MEAGER. HAVE TRIMMED BACK POPS OVER PREVIOUS FORECAST. MODELS WHICH DO GENERATE PRECIP FOCUS MAINLY SOUTH OF DC...AND HAVE THUS LEFT A 30 POP THERE. HIGHS TODAY STILL ABLE TO WARM INTO THE 80S IN MOST LOCALES. FRONT MAY MAKE IT TOWARD SOUTHERN VA TONIGHT. ANY SHOWERS WILL TAPER OFF DURING THE EVENING WITH A DRY OVERNIGHT. A BIT OF LOWER DEWPOINT PUSH IN N/W CWA...BUT OVERALL STILL EXPECTING LOWS IN THE 60S TO AROUND 70 IN URBAN CENTERS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... LOW PRESSURE WILL BE TRACKING ALONG THE FRONTAL ZONE...REACHING THE LOWER OHIO VALLEY ON THURSDAY. THIS WILL DRAW SOME MOISTURE INTO THE FRONT OVER OUR REGION. STILL SOME TIMING/PLACEMENT DIFFERENCES AMONGST MODELS...BUT EXPECT A S TO N PROGRESSION OF SHOWERS AND EMBEDDED THUNDER (AT LEAST SOME INSTBY MAY BE PRESENT...ESPECIALLY SOUTHERN TIER). QUESTIONABLE HOW MUCH IF ANY PRECIP REACHES THE M-D LINE DURING THE DAY ON THURSDAY. HEAVIEST ACTIVITY LIKELY STAYS OVER OHIO VALLEY DURING THE DAY. TEMPERATURES WILL BE LIMITED DOWN A FEW DEGREES BY THE CLOUDS AND PRECIP...UPPER 70S TO MID 80S. THURDAY NIGHT THROUGH FRIDAY NIGHT...A GREAT DEAL OF UNCERTAINTY REMAINS...WITH DIFFERING SOLUTIONS ABOUT THE PATH AND TIMING OF LOW PRESSURE SYSTEMS RIDING EAST ALONG THE FRONT. SOME GUIDANCE LIKE THE GFS BRINGS A SIGNIFICANT WAVE OF LOW PRESSURE SLOWLY ACROSS THE REGION DURING THIS PERIOD...WHICH WOULD RESULT IN SHOWERS AND PERHAPS A FEW ISOLATED THUNDERSTORMS. THE EUROPEAN IN CONTRAST IS NOTABLY SLOWER...WITH THE MAIN WAVE OF LOW PRESSURE WAITING UNTIL FRIDAY NIGHT TO BEGIN AFFECTING THE AREA. THE CANADIAN GGEM IS EVEN SLOWER...HOLDING THE MOST SIGNIFICANT LOW BACK EVEN LONGER. WITH CONSIDERABLE UNCERTAINTY IN THE FORECAST...NO SIGNIFICANT CHANGES WERE MADE...SO KEPT CHANCE TO LOW- END LIKELY POPS AND TEMPS SOMEWHAT COOLER THAN NORMAL IN THE FORECAST. && .LONG TERM /SATURDAY THROUGH TUESDAY/... UNCERTAINTY REMAINS ABOUT THE WEEKEND INTO EARLY NEXT WEEK WITH THE AFOREMENTIONED SIGNIFICANT TIMING DISCREPENCIES REGARDING PASSING DISTURBANCES BETWEEN VARIOUS MODELS. THIS MAKES ANY ATTEMPT TO IRON OUT DETAILS VERY DIFFICULT. THE ONE CONSTANT IS THE APPARENTLY NEVER LEAVING QUASI-STATIONARY FRONT. INHERITED GENERALLY CHANCE POPS THRU THE PERIOD AND DID NOT MAKE MAJOR CHANGES. TEMPS START OUT BELOW NORMAL AND *MAY* RISE TO NEAR NORMAL IF THE FRONT CAN FINALLY NUDGE ITS WAY NORTH OF US EARLY NEXT WEEK. CONFIDENCE IS LOW. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... PRECIP HAS EXITED THE AREA AND AM NOT EXPECTING FURTHER IMPACTS THROUGH THE MORNING. WILL HAVE TO WATCH POTENTIAL FOR LOW CIGS DEVELOPING THROUGH DAYBREAK...PERHAPS SOME FOG TOO...BUT THINK MID LEVEL CLOUDS WILL HELP LIMIT THIS. TODAY SHOULD BE LARGELY VFR...BUT FRONT SINKING INTO AREA MAY DEVELOP ISOLATED THUNDERSTORMS THIS AFTERNOON. IMPACTS SEEM UNLIKELY. NEXT CHANCE OF PRECIP WILL ARRIVE THURSDAY...WITH GREATEST POTENTIAL FOR IMPACTS AT CHO. FROM THURSDAY NIGHT ONWARD...MAIN CONCERN IS POSSIBLE IFR CIGS AND VIS FROM OCCASIONAL HEAVIER SHOWERS OR THUNDERSTORMS AS A FRONT REMAINS STALLED IN THE GENERAL AREA. WITH THE FRONT NEARBY...WINDS WILL BE HARD TO PREDICT WITH SIGNIFICANT CERTAINTY UNTIL THE PERIOD DRAWS CLOSER. && .MARINE... WINDS HAVE TAKEN DOWNTURN AFTER EXITING STORMS AND SCA SHOULD EXPIRE ON TIME. GRADIENT WEAK ENOUGH THAT WINDS WILL BE IN THE 10 KT RANGE FROM THE SW TODAY. AN ISOLATED STORM IS POSSIBLE BY MID- LATE AFTERNOON...BUT THIS IS IN QUESTION. EXPECT SUB-SCA WINDS THROUGH THURSDAY...EVENTUALLY TAKING ON NORTHERLY COMPONENT. MAIN CONCERN IN THE EXTENDED FOR MARINE IS OCCASIONAL HEAVIER SHOWERS AND THUNDERSTORMS...WITH APPEARS POSSIBLE JUST ABOUT EVERY DAY FROM FRIDAY INTO EARLY NEXT WEEK. WINDS SHOULD GENERALLY BE SUB SCA BUT AS DISTURBANCES PASS THRU THE AREA...A PERIOD OF SCA WINDS IS NOT IMPOSSIBLE. && .TIDES/COASTAL FLOODING... WATER LVLS RUNNING ABOVE NORMAL EARLY THIS MORNING...MODULATED BY RECENT STORMS. HOWEVER...STILL SHOULD BE ENOUGH ABOVE NORMAL FOR POTENTIAL MINOR COASTAL FLOODING AT ANNAPOLIS AND DC/ALEXANDRIA FOR MORNING TIDE CYCLE. LOW CONFIDENCE ON ANY FUTURE TIDE ISSUES...BUT ANOMALIES SHOULD DECREASE SOME AS FRONT PUSHES THROUGH. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR DCZ001. MD...COASTAL FLOOD ADVISORY UNTIL 7 AM EDT THIS MORNING FOR MDZ014. COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR MDZ013. VA...COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR VAZ053-054. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR ANZ531>533-537-539>542. SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ534-543. COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR ANZ535. && $$ SYNOPSIS...RCM NEAR TERM...ADS SHORT TERM...ADS/RCM LONG TERM...RCM AVIATION...ADS/RCM MARINE...ADS/RCM TIDES/COASTAL FLOODING...

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