Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 030802 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 402 AM EDT FRI JUL 3 2015 .SYNOPSIS... A STATIONARY FRONT OVER NORTH CAROLINA WILL DRIFT NORTH AS LOW PRESSURE MOVES EAST ALONG THE FRONT AND CROSSES THE CENTRAL MID- ATLANTIC LATE TONIGHT INTO SATURDAY. HIGH PRESSURE BUILDS SUNDAY. AN UPPER LEVEL DISTURBANCE LINGERS OVER THE SOUTHERN MID-ATLANTIC MONDAY AND TUESDAY BEFORE A COLD FRONT ENTERS THE AREA WEDNESDAY. && .NEAR TERM /THROUGH SATURDAY/... AS OF 07Z...STATIONARY FRONT IS ANALYZED OVER NC. CLEAR CONDITIONS OVER THE AREA HAS ALLOWED AREAS OF GROUND FOG TO DEVELOP WITH THICKER FOG IN VALLEYS AND ON THE PIEDMONT. WILL CONTINUE TO ASSESS AND ISSUE A DENSE FOG ADVISORY BEFORE SUNRISE AS NECESSARY. TODAY...WEAK LOW PRESSURE DRIFTS EAST ALONG THE OHIO RIVER...LIFTING THE STATIONARY FRONT NORTH AS A WARM FRONT. ERN EXTENT OF PREFRONTAL RAIN CURRENTLY OVER FAR WRN VA WILL SHIFT NE INTO SWRN ZONES LATER THIS MORNING. RAIN COVERAGE INCREASES THIS AFTERNOON WITH EMBEDDED ISOLATED TSTMS ROUGHLY KCHO AND S/W. MAX TEMPS LIMITED BY INCREASING HIGH CLOUDS AND AFTERNOON CU FIELD (AS WELL AS RAIN IN SWRN HALF OF CWA)...EXPECT MID TO UPR 70S INLAND...AROUND 80F NEAR SHORE. TONIGHT...WARM FRONT LIFTS INTO THE AREA AS WEAK LOW CENTER DRIFTS EAST ACROSS THE CWA. EXACT TRACK WILL DETERMINE INSTABILITY/TSTM THREAT AS WELL AS BE THE AXIS OF HEAVIEST RAINFALL. RAISED CATEGORICAL POPS FOR MUCH OF THE PIEDMONT AND WEST. QPF GENERALLY A QUARTER INCH TO AN INCH. FOURTH OF JULY...WEAK LOW SHIFTS EAST TO THE BAY IN THE MORNING WITH TRAILING FRONT DRIFTING SOUTH AS A COLD FRONT. PLENTY OF FRONTAL FORCING TO CAUSE RAIN...SO LIKELIES AS BACK IN THE FORECAST. WIDESPREAD CLOUD COVER SHOULD LIMIT INSTABILITY WITH BEST THUNDER CHANCES SOUTH OF THE FRONT IN THE WARM SECTOR. NWLY FLOW BEGINS IN THE AFTERNOON WITH PRECIP GENERALLY TAPERING OFF FROM NW TO SE. MAX TEMPS UPR 70S NW...LOW 80S SE. && .SHORT TERM /SATURDAY NIGHT/... BY 00Z SUN...SFC LP PROGGED TO BE MOVING AWAY FROM OUR AREA. HAD A HARD TIME REMOVING POPS ENTIRELY UNTIL AFTER 03Z...AS UNCERTAINTY REMAINS AND...WITH 4TH ACTIVITIES...ITS BETTER TO AT LEAST PREPARE FOR THAT POSSIBILITY. SAME PHILOSOPHY WITH THUNDER...THINK CHCS ARE VERY LOW FOR THUNDER TO LINGER BEYOND 00Z...BUT THOUGHT IT WAS AT LEAST WORTH KEEPING THROUGH 01Z FOR THE LOW-END POSSIBILITY. ONCE RAIN PULLS AWAY...EXPECTING A GRADUAL CLEARING TREND THROUGH THE DAY SUN...AHEAD OF THE NEXT SYSTEM APPROACHING FROM THE SW. TEMPS EXPECTED TO BE IN L80S WITH LIGHT WINDS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... FAIRLY WEAK FLOW PATTERN AT MID AND UPPER LEVELS THROUGH THE EXTENDED...WITH WAVES OF ENERGY MOVING THROUGH THE FLOW NEAR OUR AREA. FIRST WAVE APPROACHES LATE SUN OR EARLY MON...BRINGING WITH IT A CHC FOR SHWRS AND TSTMS AS SFC LOW TRACKS NEAR OUR AREA. NEXT WAVE AND ASSOCIATED CF APPROACH THE AREA AROUND WED AND IS MORE PROGRESSIVE/COMPACT. WHILE TSTMS ARE FORECAST NEARLY EACH DAY...ACTIVITY WILL BE MAINLY DIURNALLY DRIVEN...AND WITH WEAK MID LEVEL FLOW...ATM NOT EXPECTING CONVECTIVE ACTIVITY TO BE VERY ORGANIZED. QUASI-ZONAL FLOW BY MID-WEEK WILL HELP TO KEEP TEMPERATURES NEAR CLIMO NORMS. THERE IS A HINT OF MID/UPPER LEVEL RIDGING TRYING TO BUILD IN TOWARDS THE END OF THE WEEK...WHICH COULD LEAD TO TEMPS SLOWLY INCREASING TO AOA CLIMO NORMS. HUMIDITY WILL ALSO BE TOLERABLE WITH DEWPOINTS GENERALLY REMAINING AOB 70F. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... STATIONARY FRONT OVER NC THIS MORNING. CLEAR SKIES HAVE ALLOWED GROUND AND SOME THICKER FOG IN PLACES. HIGH CLOUDS WILL OVERSPREAD THE AREA REST OF THE NIGHT WITH CONDITIONS IMPROVING WITH SUNRISE. THE FRONT DRIFTS NORTH THROUGH TONIGHT AS LOW PRESSURE RIDES EAST FROM THE OHIO VALLEY. THE LOW MOVES EAST OF THE DC METROS SATURDAY AFTERNOON. GENERALLY MVFR CONDS IN LIKELY RAIN ACROSS THE TERMINALS. BEST TSTM CHANCES SOUTH OF DC METROS SATURDAY. CONDS EXPECTED TO IMPROVE THROUGH THE DAY SUNDAY...WITH LIGHT WINDS AND LITTLE CHCS FOR PRECIP AT THE TERMINALS. NEXT AVIATION CONCERNS POSSIBLE LATE SUN THROUGH MON AS NEXT SYSTEM APPROACHES AND BRINGS CHCS FOR SHWRS/TSTMS. SUB-VFR CONDITIONS POSSIBLE NEAR TSTMS...WITH VFR ELSEWHERE. && .MARINE... ONSHORE FLOW TODAY NORTH OF A STATIONARY FRONT OVER NC. WILL RAISE AN SCA FOR SRN MD WATERS SATURDAY MORNING AS WEAK LOW PRESSURE CROSSES WITH SLY FLOW GUSTING UP TO 20 KT. ISOLATED GUSTY THUNDERSTORMS LATE TONIGHT THROUGH SATURDAY AS LOW PRESSURE CROSSES. WINDS ARE EXPECTED TO REMAIN BELOW SCA LEVELS THROUGH THE EXTENDED PERIOD UNDER LIGHT AND VARIABLE FLOW. HOWEVER...MARINERS ARE ADVISED TO MONITOR FOR TSTMS...AS ISO TSTMS ARE POSSIBLE NEARLY EACH DAY...WITH THE BEST CHCS MON AND WED. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BAJ NEAR TERM...BAJ SHORT TERM...MSE LONG TERM...MSE AVIATION...BAJ/MSE MARINE...BAJ/MSE

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