Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 301441 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1041 AM EDT WED JUL 30 2014 .SYNOPSIS...
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SURFACE HIGH PRESSURE PERSISTS OVER THE MID-ATLANTIC. UPPER LEVEL LOW PRESSURE OVER EASTERN ONTARIO CONTINUES TO SPIN COOL AIR INTO THE REGION. THIS WILL GRADUALLY RECEDE AS THE WEEK PROGRESSES. A COASTAL FRONT WILL DEVELOP THIS WEEKEND AND LAST INTO EARLY NEXT WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SURFACE HIGH PRESSURE OVER THE REGION LATE THIS MORNING. A WEAK COLD FRONT OVER LAKES ERIE/ONTARIO HAS GENERATED SOME SHOWERS AND THUNDERSTORM ACTIVITY UPSTREAM. THIS COLD FRONT IS EXPECTED TO WEAKEN TODAY...BUT AN UPPER TROUGH WILL MOVE IN FROM THE SAME REGION. MEANWHILE...MODELS INDICATE POTENTIAL FOR A LEE TROUGH DEVELOPING NEAR THE BLUE RIDGE THIS AFTERNOON. WITH THIS IN MIND...WILL CONTINUE WITH SLIGHT CHANCE AND CHANCE POPS THIS AFTERNOON ALONG AND WEST OF THE BLUE RIDGE. 12Z IAD MODIFIED SOUNDING LACKS INSTABILITY WITH A DRY VERTICAL COLUMN...BUT FORECAST SOUNDINGS FOR POINTS OVER THE MOUNTAINS ARE SOMEWHAT MORE MOIST WITH NEGATIVE LIFTED INDICES. WILL KEEP SLIGHT CHANCE THUNDER OVER THE POTOMAC HIGHLANDS AND JUST SHOWERS OVER THE SHENANDOAH VALLEY. AFTER MORNING LOWS IN THE UPPER 40S TO AROUND 50 IN METRO DC...TEMPS HAVE REBOUNDED QUICKLY THIS MORNING UNDER FULL SUN. HIGHS GENERALLY IN THE LOW TO MID 80S EXPECTED THIS AFTERNOON.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... ANY RW SHOULD DIE OUT DURG THE EVE..THEN AGN NO PROBS TNGT. LOWS IN THE 50S OUTSIDE OF THE CITIES/ALONG THE WATER. TEMP MODIFICATION OF THE AIR MASS SHOULD BEGIN ON THUR - THE FINAL DAY OF JUL..BUT STILL HIGHS SHOULD STILL BE SLTLY BLO CLIMO NORMS - IN THE M80S. LOWS THU NGT IN THE LM60S AWAY FM THE CITIES. NO ORGANIZED CVCTN FORESEEN THRU THU NGT...PSBLY ISOLD TSTMS OVR THE MTNS THU AFTN. WINDS FIELDS LOOK TO BE LGT SO ANYTHING THAT WOULD GO UP WOULD PRBLY QUICKLY COME DOWN. && .LONG TERM /FRIDAY THROUGH TUESDAY/... THE WKND FCST WL FEATURE HIPRES IN THE WRN ATLC AND A TROF AXIS ACRS THE GRTLKS/MS RVR VLY. CWFA WL BE W/IN ZONE OF POS ADVCTN...BOTH TEMPS AND DEWPTS. FLOW WL STILL BE LGT...THX TO INFLUENCE OF LLVL RDGG...BUT WL HV ORIGINS FM BOTH GLFMEX AND ATLC SOURCES. DONT THINK THERE WL BE TOO MUCH INSTBY ARND FRI. BOTH WKND DAYS WL BE BETTER. CONTD POPS FOR ALL THREE...W/ DIURNAL THUNDER EMPHASIS. UPR TROF WL FLATTEN ELY NXT WK. AS HGTS RISE...PTTN WL RETURN TO SOMETHING MORE TYPICAL FOR AUG...THO STILL A LTL COOLER THAN NRML. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... VFR CONDS XPCTD TDA THRU THU NGT. VFR WL PREVAIL FOR A MAJORITY OF THE TIME FRI-SUN...THO FLGT RESTRICTIONS LKLY INVOF SCT SHRA/TSRA. && .MARINE... NO PROBS FORESEEN ON THE WATERS IN NEXT 48 HRS. SELY WNDS FRI-SUN AS AIR CIRCULATES ARND LRG HIPRES IN THE WRN ATLC. RDG CLOSE ENUF THAT SPDS SHUD BE AOB 10 KT. MAY HV A FEW STORMS. LTNG BIGGEST THREAT. && .CLIMATE...
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RECORD LOW OF 48 DEGREES SET EARLY THIS MORNING AT IAD...AND A RECORD LOW OF 55 WAS SET AT BWI.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ NEAR TERM UPDATE...KCS CLIMATE...KCS PREVIOUS...WOODY!/HTS

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