Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 161859 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 259 PM EDT WED JUL 16 2014 .SYNOPSIS... CANADIAN HIGH PRESSURE WILL BUILD OVERHEAD FOR TODAY THROUGH THURSDAY NIGHT. HIGH PRESSURE WILL MOVE OFF THE COAST FRIDAY THROUGH THE WEEKEND AND A SOUTHERLY RETURN FLOW WILL USHER IN MORE HUMID CONDITIONS ALONG WITH THE CHANCE FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/...
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A DAY AFTER SITTING IN FRONT OF A POTENT UPPER LEVEL TROUGH AXIS W/ HIGH BOUNDARY...WE`RE NOW ON THE OPPOSITE SIDE WHERE COOLER AND DRIER CONDITIONS PREVAIL. THE COLD FRONT HAS NOT MOVED TOO FAR TO THE EAST...JUST OFF THE ATLC COAST. A POTENT AND ANOMALOUSLY COLD UPPER IS ALSO EXITING TO THE NW - NORTH OF THE ST. LAWRENCE CHANNEL...BUT ANOTHER TROUGH IS DIGGING DUE SOUTH AND JUST TO OUR WEST. THIS WILL KEEP OUR WX COOLER AND QUIETER TO CLOSE OUT THE WORK WEEK. DRY SWLY UPPER FLOW IS PULLING-IN A SOLID REGION OF MID-LEVEL SUBSIDENCE...POWERING THE SFC HIGH OVER MUCH OF THE EAST COAST STATES. BREEZY NW WINDS WILL SUBSIDE BY SUNSET...BUT ALSO REINFORCE THE COOLER AND DRIER AIR UNTIL THEN. WINDS WILL STAY OUT OF THE NW FOR THE NEXT DAY OR SO...KEEPING DEWPOINTS LEVELED-OFF IN THE 50S AND L60S - W/ SOME 40S APPEARING ACROSS THE CNTRL APLCNS. OVERNIGHT LOWS WILL NEARLY REFLECT THIS DROP...TAKING A DIVE BACK INTO THE 50S W OF THE BLUE RIDGE AND LIKELY HOVERING IN THE L-M60S FOR THE PIEDMONT AND I-95 CORRIDOR.
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... THU WL BE A QUIET DAY WXWISE AS HIPRES CONTS TO BLD OVER THE MID ATLC. IT/LL BE OVHD /OR MORE PRECISELY OVER PA/ BY THU NGT. ONLY WRINKLE WUD BE S/WV ENERGY DROPPING INTO THE RETREATING H5 TROF AXIS. THAT MAY ACCOUNT FOR A FEW MORE CU DURING THE DAYTIME...BUT THINK AMS STILL MUCH TOO DRY TO SUPPORT DIURNAL SHRA. MAXT QUITE SIMLR TO WED. MIN-T WL BE A BIT WARMER AS DEWPTS RECOVER IN WK WAA BY THU NGT. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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SLOW MOISTURE RETURN ENSUES FRIDAY AS HIGH PRESSURE BUILDS OFFSHORE AND SOUTHERLY FETCH DEVELOPS. SHORT WAVE IN SOUTHWEST FLOW ALOFT ALONG WITH SURFACE INVERTED TROUGH FEATURE MAY TRIGGER SOME LATE AFTERNOON/EVENING CONVECTION ACROSS THE APPALACHIANS...HOWEVER INSTABILITY REMAINS LOW/MARGINAL. LONG WAVE TROUGH ACROSS THE EASTERN CONUS WILL SET UP PERSISTENT SOUTHERLY FETCH THIS WEEKEND INTO NEXT WEEK. WEAK VORTS IN SOUTHWEST FLOW ALOFT WILL BRING CHANCES OF CONVECTION EACH DAY....MAINLY WEST DURING THE WEEKEND. BETTER CHANCE OF WIDESPREAD CONVECTION COMES MONDAY AS STRONGER WARM/MOISTURE ADVECTION PUSHES NORTH WITH FRONT AND UPPER LOW BEGINS TO LIFT NORTH TOWARD GREAT LAKES. CONVERGENT FLOW ALOFT ACROSS THE MID-ATLANTIC INTO TUESDAY/WEDNESDAY WILL KEEP UNSETTLED AND WET CONDITIONS IN PLACE. PWATS INCREASE TO 1.5-2 INCHES AS WELL BY MID-WEEK.
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&& .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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NW WNDS ARND 10-15 KT THRU LATE AFTN...BUT DROPPING OFF TO A LIGHT NW BREEZE AOB 5KT. DIURNAL CU WILL DISSIPATE AS WELL THIS EVE...W/ SOME MID AND UPPER DECKS LINGERING INTO OVERNIGHT. HIPRES OVR THE RGN THU-THU NGT. VFR. ONCE AGN XPCTG SCT DIURNAL CU CLDS. NW WNDS NEAR 5 KT DURING THE DAY...DIMINISHING AT NGT. HIGH PRESSURE WILL MOVE OFF THE COAST FRIDAY AND A SOUTHEAST FLOW IS EXPECTED THIS WEEKEND AND INTO NEXT WEEK. INCREASED MOISTURE FROM THE SOUTHEAST FLOW WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS EACH DAY FRIDAY...THIS WEEKEND AND INTO NEXT WEEK.
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&& .MARINE...
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BEHIND THE COLD FRONT WHICH IS SLOWLY BUT STEADILY SLIDING OFF THE ATLC COAST...NW WINDS WILL CONTINUE THRU TONIGHT AND INTO TMRW. HIGH PRESSURE OVER THE WATERS THURSDAY WILL MOVE OFF THE COAST FRIDAY THROUGH EARLY NEXT WEEK. A SOUTHEASTERLY FLOW WILL DEVELOP DURING THIS TIME...BUT THE GRADIENT SHOULD BE WEAK ENOUGH TO KEEP WIND SPEEDS BELOW SCA CRITERIA. HOWEVER...INCREASED MOISTURE WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS SUNDAY AND INTO NEXT WEEK.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE.
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&& $$ UPDATE...GMS/AEB PREV DISCUSSION...HTS/CAS

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