Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 251838 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 238 PM EDT TUE AUG 25 2015 .SYNOPSIS... HIGH PRESSURE WILL MOVE EAST FROM THE PLAINS THROUGH THE WEEK...KEEPING US DRY. MOISTURE WILL SLOWLY INCREASE EARLY NEXT WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 238 PM EDT TUESDAY... HIGH PRESSURE FROM THE PLAINS WILL SLIDE EASTWARD THIS AFTERNOON INTO TONIGHT AND MOVE YESTERDAYS COLD FRONT WITH A COUPLE OF WAVES OF LOW PRESSURE ALONG IT EASTWARD TO THE ATLANTIC COAST. ALOFT THE AXIS OF THE 5H TROUGH MOVES EAST ALONG WITH THE SFC RIDGE. NORTHWEST WINDS AROUND 5 MPH THIS AFTERNOON WILL BECOME LIGHT AND VARIABLE TONIGHT. OUTSIDE OF PATCHY FOG...MOSTLY CLEAR CONDITIONS ANTICIPATED OVERNIGHT WITH LOW TEMPERATURES FROM THE LOWER 40S IN THE COLDER VALLEYS TO THE LOWER 60S IN THE PIEDMONT. LONGWAVE UPPER TROUGH ASSOCIATED WITH GREAT LAKES LOW PRESSURE CENTER WILL CONTINUE TO SLIDE EAST WEDNESDAY...ALLOWING COOL SURFACE HIGH PRESSURE TO BUILD EASTWARD. UNDER PLENTY OF SUNSHINE...HIGH TEMPERATURES WEDNESDAY WILL REMAIN BELOW NORMAL WITH READINGS FROM AROUND 70 DEGREES IN THE WEST TO THE MID 80S IN THE EAST. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... AS OF 215 PM EDT TUESDAY... LONGWAVE TROUGH WILL REMAIN IN PLACE ACROSS THE REGION FOR MUCH OF THE PERIOD BEFORE GIVING WAY TO MORE ZONAL FLOW ON FRIDAY. THIS WILL ALLOW SURFACE HIGH PRESSURE TO GRADUALLY BUILD IN FROM THE NORTHWEST INTO THURSDAY AND THEN IN WEDGE FORMATION FROM THE NORTH/NORTHEAST BY THE END OF THE WEEK. ARRIVAL OF A REINFORCING MID LEVEL SHORTWAVE TROUGH FROM THE NORTHWEST LATER THURSDAY MAY COMBINE WITH JUST ENOUGH LOW LEVEL MOISTURE TO POP AN ISOLATED LATE DAY SHRA/TSRA MOUNTAINS THURSDAY AS PWATS BUMP UP A BIT. FLOW TURNS MORE SOUTHEAST THURSDAY NIGHT INTO FRIDAY WITH SOME MODELS INDICATING ENOUGH LOW LEVEL CONVERGENCE MAINLY SOUTHERN BLUE RIDGE TO SPARK ADDED ISOLATED CONVECTION FRIDAY EVENING. THUS WILL MAINTAIN AND SLIGHTLY EXPAND ISOLATED POPS BLUE RIDGE BOTH DAYS. OTHERWISE PARTLY SUNNY DAYS AND MOSTLY CLEAR NIGHTS PENDING THE DEGREE OF LOW LEVEL MOISTURE THAT CAN RETURN. TEMPS TO REMAIN COMFORTABLE AND MOSTLY BELOW NORMAL WITH HIGHS 70S WEST TO LOW/MID 80S EAST AND LOWS 50S MOUNTAINS TO LOW/MID 60S EAST. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 1245 PM EDT MONDAY... AS OF 1245 PM EDT TUESDAY... MEAN UPPER RIDGING ACROSS THE REGION TO START THE WEEKEND WILL BE INFILTRATED BY SLOW MOVING SHORTWAVE ENERGY THAT WILL DROP SOUTHEAST AND ATTEMPT TO LOWER 5H HEIGHTS ACROSS THE MID ATLANTIC BY EARLY NEXT WEEK. TO WHAT DEGREE THIS OCCURS REMAINS UNCERTAIN ESPECIALLY GIVEN POTENTIAL TO SEE RIDGING STRENGTHEN OVER THE SOUTHEAST STATES WITH APPROACH OF ERIKA FROM THE SOUTHEAST EARLY NEXT WEEK. HOWEVER DOES APPEAR THAT SURFACE HIGH PRESSURE WILL BASICALLY REMAIN ENTRENCHED OVER THE AREA...BETWEEN THE RESIDUAL FRONT OFFSHORE THE SOUTHEAST...AND MID LEVEL WEAKNESS TO THE NW. GRADUAL RETURN OF MOISTURE PER THE WEAK FLOW TURNING MORE SOUTHERLY AHEAD OF ANY UPSTREAM FEATURES AT TIMES...AND SEEN IN LATEST MODEL PWATS...SUPPORTS SOME INCREASE IN DAILY DIURNAL CONVECTION THROUGH MOST OF THE PERIOD. THIS PRIMARILY ACROSS THE RIDGES WHERE AIDED BY OROGRAPHICS...WITH BEST CHANCES PERHAPS SUNDAY GIVEN SOME COOLING ALOFT...AND POSSIBLE REMNANT WAVE OF DANNY SLIDING UP ALONG THE FRONT PER GFS BEFORE UPPER RIDGING STRENGTHENS AGAIN EARLY NEXT WEEK. OTHERWISE AN OVERALL PERSISTENCE FORECAST WITH PC WEST TO MOSTLY SUNNY EAST DURING THE DAY INCLUDING ISOLATED TO WIDELY SCATTERED CONVECTION...THEN MOSTLY CLEAR OVERNIGHT. WILL BECOME MORE HOT/HUMID THROUGH THE PERIOD GIVEN MOISTURE ADVECTION AND WARMING ALOFT WHICH SHOULD PUSH HIGHS CLOSER TO 90 EAST WITH MOSTLY 80S ELSEWHERE FOR NOW. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... AS OF 137 PM EDT TUESDAY... HIGH PRESSURE WILL CONTROL OUR WEATHER THIS AFTERNOON INTO WEDNESDAY. ISOLATED TO SCATTERED CU WILL DISSIPATE THIS EVENING WITH THE LOSS OF SOLAR HEATING. PATCHY FOG MAY DEVELOP IN THE RIVER VALLEY TONIGHT INTO WEDNESDAY MORNING. THE TAF SITE WITH THE BEST CHANCE OF FOG LATE TONIGHT WILL BE AT LWB. ANY FOG WILL LIFT QUICKLY WEDNESDAY MORNING...LEAVING VFR CONDITIONS INTO WEDNESDAY AFTERNOON. GOOD CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE TAF PERIODS. EXTENDED AVIATION DISCUSSION... HIGH PRESSURE CONTROLS OUR WEATHER THROUGH MIDWEEK KEEPING IT VFR. MAY SEE SOME LATE NIGHT/EARLY MORNING PATCHY FOG THAT DISSIPATES QUICKLY AFTER SUNRISE IN THE FAVORED TERMINALS LWB/BCB. INCREASED CHANCES FOR SHOWERS/THUNDERSTORMS BY LATE THIS WEEKEND AS MOISTURE FROM THE SOUTHEAST STATES WORKS ITS WAY NORTHWARD INTO THE AREA. && .EQUIPMENT... BLACKSBURG RADAR REMAIN DOWN FOR SOFTWARE AND HARDWARE UPGRADES INTO EARLY AFTERNOON. RADAR SHOULD BE UP BY 20Z/4PM EDT THIS AFTERNOON. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK/WP NEAR TERM...KK SHORT TERM...JH LONG TERM...JH AVIATION...KK/WP EQUIPMENT...

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