Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 050554 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 154 AM EDT SUN JUL 5 2015 .SYNOPSIS... LOW PRESSURE MOVING OFF THE MIDDLE ATLANTIC COAST WILL PUSH A COLD FRONT SOUTHWARD TONIGHT INTO SUNDAY. THIS WILL RESULT IN ROUNDS OF SHOWERS AND THUNDERSTORMS. THE UNSETTLED WEATHER WILL CONTINUE TO AFFECT THE REGION FOR THE NEXT SEVERAL DAYS...KEEPING A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST THROUGH THE FIRST PART OF NEXT WEEK...AS TEMPERATURES BEGIN A GRADUAL WARMING TREND. && .NEAR TERM /THROUGH TODAY/... AS OF 1030 PM EDT SATURDAY... SEVERAL MODELS SHOWING PRECIPITATION ASSOCIATED WITH CLOSED UPPER LOW OVER WESTERN TENNESSEE WILL MOVE INTO SOUTHWEST VIRGINIA AND NORTHWEST NORTH CAROLINA EARLY SUNDAY MORNING. HAVE INCREASED THE PROBABILITY OF PRECIPITATION IN THAT AREA FROM 2AM THROUGH 8AM SUNDAY. A WAVY FRONTAL BOUNDARY REMAIN ACROSS THE REGION ON SUNDAY. SHORTWAVES CONTINUE TO TRAVEL EAST ALONG THE UPPER TROUGH. SHOWERS AND THUNDERSTORMS WILL BECOME NUMEROUS BY SUNDAY AFTERNOON. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... AS OF 330 PM EDT SATURDAY... MODELS ARE IN AGREEMENT WITH RESPECT TO THE DEVELOPMENT OF A WEAK CLOSED UPPER LOW ACROSS THE SOUTHEAST STATES AND ITS SUBSEQUENT NORTHWARD DRIFT INTO THE FIRST PART OF NEXT WEEK.TAIL END OF LONG STANDING EASTERN U.S. TROUGH WILL BECOME CUTOFF ACROSS NORTHERN GA/AL/EASTERN TN FROM THE PARENT UPPER TROUGH...WHICH WILL SHEAR OUT ACROSS NEW ENGLAND AS A SHORT WAVE RIDGE DRIFTS INTO THE OH VALLEY. THE UPPER LOW WILL THEN DRIFT SLOWLY NORTHEAST INTO MON...FINALLY LIFTING NORTH OF THE REGION BY TUESDAY AS THE NEXT UPSTREAM TROUGH DIGS INTO THE GREAT LAKES REGION. AS THE LOW MOVES NORTH FROM GA IT TAKES ON A NEGATIVE TILT...WHICH WILL FURTHER ENHANCE OVERALL WEAK DYNAMICS/LIFT AND CERTAINLY PROLONG THE WET WEATHER PATTERN. ABUNDANT DEEP MOISTURE WILL REMAIN IN PLACE WITH PWATS IN THE 1.75 TO 2.0 INCH RANGE ACROSS MUCH OF THE CWA. EXTENSIVE TO NEAR SOLID CLOUD COVER WILL LIMIT HEATING...SO INSTABILITIES REMAIN MEAGER AND OVERALL DYNAMICS ARE WEAK. MODELS ARE IN GOOD AGREEMENT WITH A LARGE SWATH OF DEEP MOISTURE...ASSOCIATED WITH THE UPPER LOW AND OVERRUNNING EXISTING SURFACE FRONTAL BOUNDARY...TRACKING FROM GA/SC NORTHWARD INTO THE RNK CWA BY SUN AFTERNOON...DRIFTING INTO THE NORTHERN PARTS OF THE CWA MON...THEN FINALLY LIFTING NORTHEAST OF THE CWA BY TUE. THIS WILL SUPPORT HIGH PROBABILITY OF RAINFALL FROM SUNDAY THROUGH MONDAY ACROSS MUCH OF THE CWA...WITH A LIMITED DIURNAL SWING OF TEMPERATURE GIVEN THE UPPER LOW WILL ESSENTIALLY BE DRIFTING RIGHT ACROSS THE HEART OF THE CWA. THE PATH OF THE UPPER LOW SHOULD FOCUS THE HEAVIEST RAINFALL ACROSS THE WESTERN PART OF THE CWA...BLUE RIDGE AND WEST. WITH 3HR FFG VALUES AVERAGING IN THE 1.5 TO 2.5 INCH RANGE ACROSS MUCH OF THE CWA AND THE RECENT PROLONGED WET SPELL...WE WILL NEED TO MONITOR RAINFALL AMOUNTS CAREFULLY...HOWEVER...THE LACK OF ANY ORGANIZED OR STRONG CONVECTION...GIVEN THE MEAGER LAPSE RATES AND LACK OF INSTABILITY/DYNAMICS...SHOULD HOLD HOURLY RAINFALL AMOUNTS IN CHECK. WILL CONTINUE TO HIGHLIGHT THREAT OF POOR DRAINAGE FLOODING IN THE HWO...BUT POTENTIAL FOR FLASH FLOODING DOES NOT APPEAR TO BE A CONCERN ATTM. AS THE UPPER LOW DRIFTS NORTH OF THE AREA TUE...WE SHOULD SEE ENOUGH SUBSIDENCE AND DRYING TO FINALLY SQUELCH THE SHOWER THREAT PROVIDING A BREAK BEFORE NEW FRONTAL SYSTEM APPROACHES TUESDAY NIGHT OR WEDNESDAY. MAXIMUM TEMPERATURES SHOULD REMAIN BELOW NORMAL THROUGH MON...TRENDING CLOSER TO NORMAL VALUES TUESDAY WITH GREATER INSOLATION. MINIMUM TEMPERATURES WILL REMAIN ABOVE NORMAL WITH HIGH PWATS/DEWPOINTS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 445 PM EDT SATURDAY... UNSETTLED WEATHER DESTINED TO CONTINUE. AFTER A VERY BRIEF RESPITE FROM WIDESPREAD PRECIPITATION TUESDAY...A NEW FRONTAL SYSTEM WILL DRIFT INTO THE REGION FROM THE WEST BY WEDNESDAY AND THEN BECOME ELONGATED WEST-EAST ACROSS THE REGION AND STALL FOR THE LATTER HALF OF THE WEEK. WITH SUBTROPICAL RIDGING TO OUR SOUTH AND FASTER WESTERLIES TO OUR NORTH...THIS WILL FAVOR ACTIVE BAROCLINIC ZONE WITH DAILY THREAT FOR SHOWERS/STORMS. PATTERN SUPPORTS SOME ORGANIZATION OF STORM ACTIVITY AND POTENTIAL FOR STRONG/SEVERE STORMS PER PRESENCE OF WITH ASSOCIATED UPPER LEVEL SHORT WAVE ENERGY THAT WILL BE PASSING THROUGH THE FASTER WESTERLIES TO OUR NORTH. THE UPPER FLOW ATTEMPTS TO TRANSITION BACK TO NORTHWEST FLOW TOWARD THE WEEKEND AS UPPER RIDING AMPLIFIES ACROSS THE WEST- CENTRAL CONUS. THIS COULD REDUCE THE POTENTIAL FOR PROLONGED CONVECTION/RAINFALL...BUT WILL NONETHELESS SUPPORT AN ACTIVE AND UNSETTLED WEATHER PATTERN. WITH ABOVE AVERAGE CLOUD COVER AND MOISTURE LEVELS CONTINUING...EXPECT NEAR TO SLIGHTLY BELOW NORMAL MAX TEMPERATURES AND WELL ABOVE NORMAL MINIMUM TEMPERATURES THROUGH THE WEEK. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 154 AM EDT SUNDAY... ONE AREA OF SHOWERS/EMBEDDED THUNDER WAS DIRECTLY UPSTREAM FROM KDAN SO HAVE GONE PESSIMISTIC THERE FOR THE INITIAL ONE TO TWO HOUR PERIOD. THIS AREA OF PRECIPITATION IS CURRENTLY WEAKENING SO WILL AMEND AS NEEDED. AVIATION CONDITIONS WILL BE QUITE POOR TODAY AS A CLOSED LOW DEVELOPS ALOFT STAYS JUST TO OUR WEST THROUGH THE PERIOD...WHILE A SURFACE LOW SLIDES INTO THE WESTERN PORTION OF OUR AREA ALONG THE OLD LINGERING FRONTAL BOUNDARY THAT HAS BEEN WAVERING ABOUT FOR THE PAST SEVERAL DAYS. THIS WILL ESTABLISH A DEEP AND PERSISTENT E/SE WIND FLOW WITH EXCELLENT MOISTURE TRANSPORT INTO THE TAF SITES. EXPECT MVFR/IFR CONDITIONS TO MOVE IN FROM THE WEST OVERNIGHT BEFORE BOUNCING BACK UP TO AOA VFR BY LATE MORNING/EARLY AFTERNOON. PRECIPITATION CHANCES WILL BE INCREASING THROUGHOUT THE MORNING WITH THE WORST CONDITIONS HOLDING OFF UNTIL THE AFTERNOON WHEN THERE WILL ALSO BE SOME EMBEDDED THUNDER. THERE ARE INDICATIONS FOR SPOTTY IMPROVEMENT LATE IN THE PERIOD BUT DO NOT HAVE ENOUGH CONFIDENCE IN EXACTLY WHERE/WHEN SO WILL STAY PESSIMISTIC THROUGH THE END OF THE VALID PERIOD. EXTENDED AVIATION DISCUSSION... POOR AVIATION CONDITIONS TO CONTINUE INTO NEXT WEEK...BUT WINDOWS OF OPPORTUNITY FOR VFR CONDITIONS INCREASE TUE. UPPER LOW/TROUGH WILL MOVE INTO OHIO BY MONDAY. MEANWHILE...A COLD FRONT WILL APPROACH FROM THE OH VALLEY BY WED. THIS LEAVES A VERY UNSETTLED/WET PATTERN ACROSS THE REGION THROUGH THE PERIOD. EXPECT WIDESPREAD LATE NIGHT/EARLY MORNING LOW CLOUDS/FOG WITH IFR-LIFR CIGS/VSBYS. OVERALL...CONDITIONS SHOULD IMPROVE TO MVFR- VFR OUTSIDE SHRA/TSRA ACTIVITY DURING THE AFTERNOONS. AT THIS POINT...TUESDAY APPEARS TO OFFER THE BEST OPPORTUNITY FOR MORE WIDESPREAD VFR CONDITIONS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK NEAR TERM...AMS/KK SHORT TERM...PM LONG TERM...PM/RAB AVIATION...MBS/AMS

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