AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 745 PM EDT THU JUL 7 2011 .SYNOPSIS... AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL REMAIN TO OUR WEST TONIGHT...THEN AMPLIFY ON FRIDAY AS IT MOVES CLOSER TO THE REGION. THIS WILL PUSH A COLD FRONT THROUGH THE MID ATLANTIC STATES FRIDAY NIGHT INTO SATURDAY. DRIER CONDITIONS WILL MOVE INTO THE AREA FROM SATURDAY AFTERNOON THROUGH SUNDAY...AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... LATEST SFC ANALYSIS SHOWS A WEAK TROUGH EXTENDING FROM N OF DC SOUTHWEST TO ROANOKE. SCATTERED CONVECTION HAS DEVELOPED ALONG AND AHEAD OF THE FRONT...HAVING REACHED THE CONVECTIVE TEMP (UPPER 80S)...SUPPORTED BY A FVRBL LLVL THERMODYNAMIC SETUP (SFC BASED CAPES BTWN 3000-3500 J/KG. TOTAL-TOTALS IN THE MID-UPR 40S ARE INDICATIVE OF THE MEAGER MID LVL LAPSE RATES (5.5 TO 6 C/KM BTWN 700-500 MB)...HOWEVER...K INDICES IN THE 20S WITH WET BULB ZERO HEIGHTS AROUND 11500 KFT (SOME 3000 KFT LOWER THAN THE FREEZING LEVEL) ARE INDICATIVE OF FAIRLY PRONOUNCED DRY AIR AT MID LEVELS. THIS MAY PROVIDE SOME BRIEF GUSTY TSTM WIND GUSTS AND POTENTIALLY SOME SMALL HAIL...DESPITE (AGAIN) THE WEAK LAPSE RATES AND LIGHT WINDS ALOFT (<25 KT). OVERNIGHT...MID/UPR LEVELS MOISTEN UP ONCE AGAIN AHEAD OF THE APPROACHING MID LVL SHORTWAVE...WITH DEEP LAYER SW FLOW AS THE WARM CONVEYOR BELT (WCB) EXPANDS BACK ACROSS THE MID ATLC REGION. PWATS CLIMB BACK CLOSE TO 2" BY EARLY FRI MORNING...WITH K INDICES INTO THE MID 30S OVER WRN PTNS. MODELS SHOW MINIMAL FORCING OVERNIGHT TO FOCUS ANY ADDITIONAL CONVECTION...THOUGH DO INDICATE VERY WEAK (SUBTLE) LOW-MID LEVEL QVECTOR CONVERGENCE AND SLIGHTLY STRENGTHENING LLVL FGEN. SO...WITH THIS ALONG WITH DEEPENING MOIST LAYER...WILL MAINTAIN A MENTION OF ISOLATED-SCATTERED POPS OVERNIGHT. MIN TEMPS GENERALLY AROUND 70-LOWER 70S. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... MODELS REMAIN IN GOOD AGREEMENT WITH MID/UPPER LEVEL PATTERN OF AN AMPLIFYING TROUGH OVER THE OHIO/TN VALLEYS ON FRI...CROSSING THE MTNS FRI NIGHT INTO SAT MORNING. DYNAMICS WITH THIS SYSTEM IS RATHER IMPRESSIVE FOR EARLY JULY...WITH A DECENT SWATH OF RRQ UPPER JET FORCING (70-75 KT JET CORE AT 300 MB)...WITH THE ATTENDANT LOW-MID LEVEL FGEN AND QVECTOR CONVERGENCE. MEANWHILE...DEEP LAYER MOISTENING CONTINUES AHEAD OF THE FRONT...AS PWATS CLIMB TO OR JUST ABOVE 2.25". THEREFORE HAVE CONTINUED WITH THE HIGH (>50%) POPS WITH THE FRONTAL PASSAGE...AS WELL AS WITH THE LOCALLY HEAVY RAIN MENTION DURING THIS PERIOD. WILL ALSO HIGHLIGHT THE RISK OF LOCALLY HEAVY (LOCALIZED FLOODING) IN THE HWO. ALSO...SHEAR INCREASES LATER FRI SO THERE WILL BE AN ENHANCED RISK FOR SEVERE STORMS FRI AFTN/EVENING. LIMITING FACTOR WILL BE HOW MUCH SUN WE CAN GET ON FRI...MAIN THREATS WILL BE WET MICROBURSTS AND LARGE HAIL. HIGHS FRI WILL BE HELD DOWN SOMEWHAT BY CLOUDS...MAINLY IN THE MID-UPPER 80S. WILL LINGER POPS SAT MORNING...ESPECIALLY EAST...WITH DRIER AIR MOVING IN BY AFTN FROM THE NW. HIGHS SAT 85-90...COOLEST EAST WHERE CLOUDS HANG AROUND THE LONGEST. COOLER SAT NIGHT WITH LOWS INTO THE 60S OVER NW 1/2 OF CWA...AROUND 70 SE. DRY ON SUN WITH SEASONABLY WARM TEMPS (HIGHS FROM THE MID 80S ALONG THE ATLC COAST TO THE LOWER 90S FARTHER INLAND). && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... GOING WITH A COMBINATION OF THE 12Z GFS/ECMWF FOR THE EXTENDED PERIOD. HI PRES MOVING OFF THE NRN MID ATLC CST WILL MAINTAIN DRY WX SUN NGT AND MON. A COLD FRNT WILL APPROACH FM THE NNW LATE MON NGT THEN PUSH INTO AND ACRS THE REGION TUE INTO WED. THIS WILL RESULT IN ANOTHER SLGT OR SML CHC OF SHOWERS AND TSTMS. HI PRES WILL BLD BACK IN FM THE NNE FOR LATE WED THRU THU. MIN TEMPS WILL BE IN THE UPR 60S TO LWR 70S MON MORNG...IN THE LWR TO MID 70S TUE AND WED MORNGS...AND IN THE MID 60S TO LWR 70S THU MORNG. MAX TEMPS WILL BE IN THE UPR 80S TO MID 90S MON...IN THE UPR 80S TO LWR 90S TUE...IN THE MID 80S TO NEAR 90 WED...AND IN THE MID TO UPR 80S THU. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... SCATTERED TSTMS ACROSS PORTIONS OF SRN VA WERE NOT HEADED TOWARD ANY TAF SITES AT 23Z AND WILL LIKELY DISSIPATE DURING THURSDAY EVENING. INTRODUCED MVFR FOG FOR EARLY FRIDAY MORNING WITH SOME STRATUS IN THE 1-2K FT. RECENT NIGHTS HAVE GENERALLY STAYED ABOVE IFR AND TNGT/FRI MRNG SHOULD BE NO EXCEPTION. AM MOST CONCERNED WITH ECG WHERE WET GROUND FROM ABUNDANT RECENT RAINFALL COULD HELP TO LOWER CONDITIONS TO IFR BUT KEPT THE FCST JUST ABOVE THAT CRITERIA DURING A 09-13Z TEMPO GROUP. AN ACTIVE DAY FOR CONVECTION IS FORECAST FRIDAY AND WITH TSTMS LIKELY AT THE TAF SITES IN THE AFTERNOON...INCLUDED CB REMARKS BEGINNING AT BETWEEN 19 AND 23Z. OUTLOOK...SCTD CONVECTION IS EXPECTED THROUGH MIDDAY SATURDAY. A COLD FRONT WILL PUSH ACROSS THE REGION LATE SATURDAY AND VFR/DRY CONDITIONS ARE IN STORE FOR SUNDAY AND MONDAY. THERE IS A CHC FOR TSTMS ON TUESDAY. && .MARINE... NO HEADLINES IN THE SHRT TERM TNGT THRU SAT. HI PRES WILL BE WELL OFF THE MID ATLC/SE CST TNGT. A FRNTL BNDRY WITH AREAS OF LO PRES MOVNG ALNG IT...WILL PUSH ACRS THE AREA FRI THRU SAT. HI PRES WILL BLD BY TO OUR NNE AND OFF THE CST FOR LATE SAT THRU MON. ANOTHER COLD FRNT WILL DROP INTO THE REGION DURING TUE. WND SPDS/WAVES/SEAS WILL REMAIN BELOW SCA LVLS THRU THE PERIOD. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...BKH