Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 130758 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 358 AM EDT SAT SEP 13 2014 .SYNOPSIS... A SURFACE TROUGH WILL MOVE ACROSS THE REGION TODAY...WHILE LOW PRESSURE PASSES TO THE SOUTH AND EAST. HIGH PRESSURE BUILDS ACROSS THE MID-ATLANTIC SATURDAY EVENING THROUGH MONDAY. A WEAK DISTURBANCE PASSES THROUGH THE AREA MONDAY NIGHT. HIGH PRESSURE BUILDS IN THROUGH MIDWEEK. && .NEAR TERM /THROUGH TONIGHT/... EARLY MORNING SURFACE TROUGH EXTENDS FROM EASTERN OHIO THROUGH WV...SWRN VA AND INTO NC. SOME LIGHT RAIN HAS DEVELOPED ACROSS PORTIONS OF EASTERN WV AND WESTERN VA. MODELS CONTINUE TO INDICATE SHOWER ACTIVITY SHOULD SPREAD WEST TO EAST ACROSS THE FORECAST AREA TODAY. PLENTY OF MOISTURE EXPECTED IN THE ATMOSPHERE TODAY...WITH PWATS NEAR 2.0 INCHES...BUT INSTABILITY WILL BE LIMITED WITH A NOSE OF WARM AIR BETWEEN 700 AND 800MB AND LIMITED LAPSE RATES ABOVE IT OF AROUND 5 OR 6 DEGREES C/KM. END RESULT IS THAT MOST AREAS SHOULD SEE LESS THAN A QUARTER INCH OF RAIN TODAY...ALTHOUGH SOME AREAS MAY GET BRIEF MODERATE/HEAVY RAIN AND THEREFORE HIGHER AMOUNTS. HIGH TEMPERATURES GENERALLY IN THE LOW TO MID 70S EAST OF THE BLUE RIDGE...WITH UPPER 60S TO AROUND 70 WEST OF THE BLUE RIDGE. TROUGH IS EXPECTED TO BE OFFSHORE BY THIS EVENING. HIGH PRESSURE BUILDS IN TO THE NORTH...WITH SKIES BECOMING CLEAR TO PARTLY CLOUDY OVERNIGHT. COOLER AIR MOVES INTO THE REGION UNDER LIGHT NORTHERLY WINDS. THE LACK OF CLOUD COVER WILL SUPPORT GOOD RADIATIONAL COOLING. TEMPS WILL BECOME QUITE CHILLY OVERNIGHT. LOWS DROP INTO THE 40S ALONG AND WEST OF THE BLUE RIDGE...AND EVEN INTO THE UPPER 30S ALONG PORTIONS OF THE POTOMAC HIGHLANDS. AREAS ALONG AND EAST OF THE I-95 CORRIDOR SHOULD STAY IN THE 50S. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... THE HIGH BUILDS OVERHEAD SUNDAY...WITH MOSTLY SUNNY SKIES AND LIGHT NORTH WINDS. MILD TEMPS EXPECTED...WITH HIGHS IN THE LOW 70S ACROSS MOST OF THE REGION. BLUE RIDGE MOUNTAINS AND POTOMAC HIGHLANDS WILL BE SLIGHTLY COOLER WITH HIGHS IN THE MID TO UPPER 60S. HIGH PRESSURE REMAINS SPRAWLED ACROSS THE AREA SUNDAY NIGHT. SUBSIDENCE AND DRY AIR ALOFT WILL SUPPORT CLEAR TO PARTLY CLOUDY SKIES. TEMPERATURES SUNDAY NIGHT SHOULD BE SIMILAR TO SATURDAY NIGHT...WITH LOWS AGAIN IN THE 40S AND 50S. && .LONG TERM /MONDAY THROUGH FRIDAY/... SFC HIPRES WL BE MVG OFFSHORE MON. WL HV FAIRLY FAST FLOW ALOFT...SO THE TRANSITION SHUD BE RATHER SUDDEN...AS ISENT LIFT WL SPRED CLDS ACRS THE AREA DURING THE AFTN. DONT QUITE THINK WE/LL HV ENUF TIME FOR COMPLETE MSTR RECOVERY...SO HV KEPT POPS OUT OF THE FCST...XCPT FOR A SCHC LT DAY HIGHLAND/PENDLTN EWD TO S OF CHO. INSTEAD...THE PCPN PROGGED TO HOLD OFF TIL MON NGT. THERE ARE TWO PSBL SOURCES-- THE PACKET OF THTE GLIDING ACRS VA AND A WK CDFNT/TROF AXIS APPRCHG FM THE NW. AM NOT SURE HOW WELL THESE TWO FEATURES WL PLAY WITH EACH OTHER. IN SITUATIONS W/ CONFLICTING PRIORITIES...THE TYPICAL OUTCOME IS FOR LOTSA CLDS BUT LTL PCPN. THATS THE ROUTE TAKEN HERE. THE RRQ OF UPR JET DOES RESIDE IN THE NRN MID ATLC...SO HV LKLY POPS ALONG I-95. QPF LGT THO. WL GIVE CREDENCE TO WAA...AND BUMP MAXT UP TO MID /PERHAPS UPR/ 70S. THINK THERE WL BE JUST TOO MUCH CLDCVR FOR THE LWR 80S SUGGESTED BY MAV. MIN-T NOT FAR OFF FM DEWPTS...LWR 60S SE OF CHO-DCA-DMH...BUT IN THE 50S POINTS NW. HV STRONG CAA IN THE MTNS AFTR MIDNGT...AND THAT SHUD RESULT IN A FAIRLY WIDESPREAD RGN OF MIN-T LWR-MID 50S. THE REST OF THE XTNDD FCST WL BE DOMINATED BY SPRAWLING HIPRES. MAY HV A LINGERING SHRA NEAR THE BAY TUE MRNG. OTRW DRY WX. SKIES SHUD BE MOSUN/SUNNY BY DAY /CLR BY NGT/ TIL THU...WHEN A S/WV PASSAGE INTHE NERN CONUS MAY CONTRIBUTE A FEW CLDS. OTR CHALLENGE WL BE TEMP FCSTG. WL BE IN NW FLOW...WHICH SUGGESTS COOLER THAN CLIMO. GRIDS HV PLENTY OF UPR 60S-LWR 70S FOR MAXT. MIN-T MID 40S-MID 50S. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... SHOWER ACTIVITY IS EXPECTED DEVELOP SATURDAY AS A TROUGH MOVES ACROSS THE REGION. RAIN SHOULD BE LIGHT FOR MOST PART...WITH MVFR VSBYS. CIGS AROUND 2-3KFT EXPECTED TO DEVELOP DURING MID-LATE MORNING AND PERSIST THROUGH MOST OF THE AFTERNOON. GENERALLY LIGHT NORTHERLY WINDS...ALTHOUGH WIND DIRECTION MAY SHIFT TO THE SE BY THE END OF THE AFTERNOON OVER DC METRO TERMINALS. VFR EXPECTED SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH LIGHT WINDS. CLDS WL BE INCRSG MON...BUT FLGT RESTRICTIONS SHUD HOLD OFF TIL MON NGT. MVFR TO PERHAPS IFR DUE TO CIGS/VSBYS IN SHRA MAY LINGER INTO THE ELY PORTION OF THE TUE MRNG PUSH. VFR THEREAFTER. && .MARINE... WINDS XPCTD TO REMAIN BELOW SCA VALUES THROUGH THE DAY SAT. RAIN EXPECTED AT TIMES LATE SATURDAY MORNING THROUGH MID-LATE AFTERNOON. GRADIENT INCREASES SATURDAY EVENING WITH LOW PRESSURE OFFSHORE AND HIGH PRESSURE BUILDING TO THE NORTH AND WEST. SMALL CRAFT ADVISORY IS IN EFFECT. THE ADVISORY HAS BEEN EXTENDED INTO MID MORNING FOR THE SOUTHERNMOST MARINE ZONES. WINDS DIMINISH QUICKLY SUNDAY AFTERNOON AND CONTINUE TO BE LIGHT SUNDAY NIGHT WITH HIGH PRESSURE BUILDING OVER THE WATERS. A WK DISTURBANCE WL CROSS THE WATERS MON NGT. CAA BHD THIS FEATURE TUE WL KICK NW WNDS UP...W/ SUFFICIENT MIXING FOR SCA POTL AT THAT TIME. WNDS WL GRDLY DIMINISH AFTR THAT AS HIPRES BLDS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EDT SUNDAY FOR ANZ531-532-538>540-542. SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 AM EDT SUNDAY FOR ANZ533-534-537-541-543. && $$ SYNOPSIS...KS NEAR TERM...KS SHORT TERM...KS LONG TERM...HTS AVIATION...KS/HTS MARINE...KS/HTS

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