Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 271908 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 308 PM EDT SAT JUN 27 2015 .SYNOPSIS... A COLD FRONT WILL APPROACH THE AREA THIS EVENING...AND CROSS THROUGH AND THEN EAST OF THE REGION OVERNIGHT. COOLER...AND DRIER HIGH PRESSURE WILL BUILD INTO THE AREA FOR THE REMAINDER OF THE WEEKEND. OUR CHANGE IN WEATHER REGIMES WILL BE SHORT LIVED AS WE RETURN TO A MORE PROGRESSIVE WEATHER PATTERN NEXT WEEK...WITH SHOWERS AND STORMS IN THE FORECAST EVERY DAY FROM TUESDAY ONWARD. && .NEAR TERM /THROUGH SUNDAY NIGHT/... AS OF 230 PM EDT SATURDAY... A COLD FRONT WAS POSITIONED FROM EASTERN OHIO SOUTHWEST INTO CENTRAL TENNESSEE. ITS PARENT LOW WAS POSITIONED OVER LOWER MICHIGAN. MOIST SOUTHWEST FLOW CONTINUE TO ADVECT INTO THE AREA IN ADVANCE OF THE LOW. THE COMPLEX FROM EARLIER THIS MORNING LEFT LINGERING CLOUD COVER AND STABILITY THAT PROLONGED THE INITIATION OF MORE SUBSTANTIAL CONVECTION. AS THE AFTERNOON CONTINUES...THE TREND TOWARDS MORE DESTABILIZATION IS EXPECTED TO TRANSPIRE AS WE HEAD INTO THE REMAINDER OF THE AFTERNOON...INTO THE EARLY EVENING. THE LATEST MESOSCALE DISCUSSION FROM THE STORM PREDICTION CENTER IS EYEING THE EASTERN PARTS OF THE AREA FOR THE GREATEST POTENTIAL FOR ANY STRONG TO SEVERE STORMS...NOW THROUGH THIS EVENING. OUR CURRENT FLASH FLOOD WATCH CONTINUES UNTIL 600 PM. GIVEN HOW THE AREA IS TRANSITIONING TO CONVECTIVE BASED PRECIPITATION...RATHER THAN WIDESPREAD RAINFALL...ANY FLASH FLOODING AT THIS POINT AN ONWARD WILL BE TRIGGERED BY SLOW MOVING...OR TRAINING...THUNDERSTORM OR HEAVY RAIN SHOWERS. THE GREATEST CONCERN IS THE SAME AREA AS THE WATCH...BASED UPON THE LOWEST RIVER FORECAST CENTER FLASH FLOOD GUIDANCE. AFTER THE FRONT CROSSES THE AREA THIS EVENING...LOOK FOR AN ABRUPT WIND SHIFT NORTHWEST...WITH WINDS INCREASING IN THE MOUNTAINS OVERNIGHT. LOCATIONS IN THE PIEDMONT WILL EXPERIENCE A CHANGE TO A NORTHWEST WINDS...BUT THE NOCTURNAL INVERSION WILL LIMIT THE AMOUNTS OF SURFACE GUSTS UNTIL MIXING CAN TAKE PLACE SUNDAY MORNING. THE NORTHWEST WINDS ACROSS THE MOUNTAINS WILL BE COMPARABLE TO A WINTERTIME SCENARIO WITH UPSLOPE CLOUD COVER DEVELOPING...AND CONTINUING INTO SUNDAY. ISOLATED TO SCATTERED UPSLOPE RAIN SHOWERS WILL ALSO BE POSSIBLE...WITH DECREASING COVERAGE DURING THE DAY SUNDAY. MODEL GUIDANCE OFFERS A 850 MB WIND SOLUTION AROUND 40 TO 50 KTS ALONG THE CREST OF THE BLUE RIDGE AND POINTS WESTWARD AROUND DAYBREAK SUNDAY. THIS MAY TRANSLATE TO SURFACE GUSTS AT THE HIGHEST ELEVATIONS AROUND 40 TO 45 MPH WITH 25 TO 35 MPH MORE COMMON ACROSS THE REMAINDER OF THE AREA WEST OF THE BLUE RIDGE. WITH LEAVES ON THE TREES...AND AT LEAST A WET...IF NOT SATURATED IN SOME LOCATIONS...SOIL MOISTURES...GUSTS OF THESE SPEEDS HAVE THE POTENTIAL OF DOWNING TREES THAT OTHERWISE MAY NOT BE MORE PRONE TO FALLING. GIVEN THIS...A WIND ADVISORY WILL BE POSTED FOR LATE TONIGHT THROUGH SUNDAY AFTERNOON TO STRESS THIS POTENTIAL IMPACT ACROSS THE MOUNTAINS...RATHER THAN THE WIND ADVISORY GUSTS THAT WE TYPICALLY ARE EXPECTING WHEN ONE IS ISSUED. HIGH PRESSURE WILL BUILD OVER THE AREA SUNDAY NIGHT. ANTICIPATE A CONTINUED TREND TOWARDS COOLER TEMPERATURES...LIGHTER WINDS SPEEDS...AND LESS CLOUD COVER. FOR TEMPERATURES...LOW TEMPERATURES TONIGHT WILL BE SOME FIVE TO TEN DEGREES COOLER THAN READINGS EXPERIENCE THIS MORNING. LOOK FOR MID TO UPPER 50S ACROSS THE MOUNTAINS TO LOWER 60S ACROSS THE PIEDMONT. ON SUNDAY...HIGH TEMPERATURES WILL RANGE FROM THE MID TO UPPER 70S ACROSS THE MOUNTAINS TO AROUND 80 TO THE LOWER 80S ACROSS THE PIEDMONT. SUNDAY NIGHT WILL BE THE COOLEST NIGHT WE HAVE EXPERIENCED FOR A WHILE...AROUND 50 TO THE MID 50S ARE EXPECTED ACROSS THE MOUNTAINS TO THE MID TO UPPER 50S ACROSS THE PIEDMONT. WHILE NO RECORD LOWS ARE FORECAST SUNDAY...A FEW LOCATIONS WILL GET WITHIN FIVE DEGREES OF THEIR CORRESPONDING RECORDS. REVIEW THE CLIMATE SECTION OF THIS DISCUSSION FOR DETAILS. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 130 PM EDT SATURDAY... BROAD TROUGHING WILL DOMINATE THE EASTERN U.S. THROUGH THE PERIOD WITH BELOW NORMAL HEIGHTS AND CONSIDERABLY LOWER 850MB TEMPS THAN WE HAVE SEEN IN RECENT WEEKS. HOWEVER...THERE APPEAR TO BE NUMEROUS EMBEDDED DISTURBANCES WITHIN THE FLOW IN AN ALMOST WINTERLIKE PATTERN THAT SETS UP THROUGH THE PERIOD. OVERALL THE PATTERN IS QUITE UNSETTLED WITH NUMEROUS CHANCES FOR SHOWERS AND THUNDERSTORMS. CLEARLY FEW IF ANY SIGNIFICANT TIME PERIODS DURING THE PERIOD WHERE POPS CAN BE LEFT UNMENTIONABLE. THE FIRST DISTURBANCE OF CONCERN ARRIVES MONDAY AFTERNOON...WITH A WEAK SFC WARM FRONT LIFTING NORTH THROUGH THE CWA. 850MB TEMPS BEING TO RISE FROM THE SINGLE DIGITS EARLY IN THE DAY TO THE 10 TO 15C RANGE BY EVENING. INSTABILITY IS MEAGER...BUT ENOUGH CREEPING IN FROM THE WEST LATE IN THE DAY WITH THE DISTURBANCE TO WARRANT THE MENTION OF TSRA. SEVERE POTENTIAL APPEARS HIGHLY UNLIKELY WITH THIS FIRST SYSTEM AND MOISTURE IS JUST BEGINNING TO RETURN IN EARNEST...SO HEAVY RAIN SHOULD NOT BE A THREAT EITHER AT THAT POINT. MUCH OF THE FOCUS OF THIS FIRST SYSTEM WILL BE WEST OF THE BLUE RIDGE...AND MORE SO ACROSS WV...LIFTING NORTHWARD TOWARD MD/PA BY EVENING. THE NEXT DISTURBANCE TO ROTATE THROUGH THE TROUGH ARRIVES TUESDAY AFTERNOON AS THE UPPER TROUGH BEGINS TO DEEPEN AND SHIFT EVER SO SLIGHTLY EAST. CONDITIONS APPEARS SLIGHTLY MORE FAVORABLE FOR STRONGER AND MORE WIDESPREAD THUNDERSTORMS WITH THIS EVENT. HOWEVER...AT THIS POINT HAVE CAPPED POPS IN THE 50 PERCENT RANGE WEST AND 40 PERCENT RANGE EAST. FOR A CHANGE...TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL AT THE BEGINNING OF THE PERIOD...MODERATING TO NEAR NORMAL READINGS BY THE END OF THE PERIOD. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 215 PM EDT SATURDAY... THE BROAD UPPER TROUGH WILL CONTINUE THROUGH THE EXTENDED PERIODS...BUT WILL GRADUALLY RETROGRADE WITH TIME. A QUITE ACTIVE BAROCLINIC ZONE APPEARS DESTINED TO BECOME ESTABLISHED FROM THE NORTHERN PLAINS ACROSS THE TN/OH VALLEY INTO THE SOUTHERN APPALACHIANS AND SOUTHEAST STATES. MODELS VARY SLIGHTLY ON THE EXACT PLACEMENT OF THIS BAROCLINIC ZONE...BUT MOST HAVE IT OVER OR VERY NEAR THE SOUTHERN END OF THE CWA THROUGH MUCH OF THE PERIOD. THE GFS IS THE MOST AGGRESSIVE IN PUSHING IT INTO THE SOUTHEAST STATES. THUS...I PREFER TO TAKE THE MORE CONSERVATIVE APPROACH AND EXPECT THE BOUNDARY TO LINGER MORE ACROSS OUR REGION. THUS...HAVE CONTINUED CHANCE TO HIGH CHANCE POPS THROUGH THE PERIOD FOR MUCH OF THE CWA...WITH THE BEST FOCUS ACROSS THE WESTERN AREAS. THE STRONGEST DISTURBANCE...A SOMEWHAT NEGATIVELY TILTED ONE AT THAT...APPEARS TO ROTATE THROUGH THE REGION FRIDAY AFTERNOON...AT WHICH TIME WOULD BE THE GREATEST THREAT FOR ANY STRONG TO SEVERE STORMS AS WELL AS HEAVY RAINFALL AS PWATS CREEP BACK CLOSE TO 2 INCHES ONCE AGAIN. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY ABOVE NORMAL THROUGH MOST OF THE PERIOD AS 850MB TEMPS GENERALLY REMAIN BELOW +20C COMPARED TO RECENT DAYS. TOWARD THE VERY END OF THE PERIOD THERE ARE SOME INDICATIONS THAT UPPER RIDGING WILL INTENSIFY ACROSS THE WESTERN ATLANTIC AS THE BROAD TROUGH ATTEMPTS TO RETROGRADE WEST. HOWEVER...SUBSTANTIAL CLOUD COVER AND MOISTURE IN OUR REGION SHOULD KEEP MOST AREAS...EXCEPT POSSIBLE THE KDAN AREA...BELOW 90S DEGREES. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... AS OF 145 PM EDT SATURDAY... THE AREA REMAINS IN THE MOIST AND PROGRESSIVELY UNSTABLE AIR IN ADVANCE OF AN APPROACHING COLD FRONT. CIGS RANGE FROM HIGH END MVFR TO LOW END VFR...AND THAT TREND ALONG WITH PROGRESSIVELY INCREASING SHOWERS AND STORMS IS EXPECTED THE REMAINDER OF THE AFTERNOON. SOME OF THE STRONGER STORMS THAT DEVELOP LATER THIS AFTERNOON MAY CONTAIN VERY GUSTY WINDS AND HAIL. THIS EVENING...A COLD FRONT WILL ACROSS THE AREA. LOOK FOR WINDS TO SHIFT NORTHEAST AND START TO INCREASE. ANTICIPATE A WINTER-LIKE UPSLOPE ENVIRONMENT WITH DECREASING CIGS INTO THE IFR/MVFR RANGE FROM SOUTHEAST WEST VIRGINIA...SOUTH INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA...ALONG WITH SOME ISOLATED TO SCATTERED UPSLOPE RAIN SHOWERS. THE REMAINDER OF THE AREA WILL PROBABLY NOT REALIZE THE SURFACE GUSTS UNTIL DAYBREAK MONDAY...AND ANTICIPATE LESS CLOUD COVER. ON MONDAY...EXPECT A GUSTY DAY...ESPECIALLY ACROSS THE MOUNTAINS AS 850 MB WINDS ARE PROGGED TO BE IN THE 40 TO 50 KT RANGE. ANY DAYBREAK SUB-VFR CONDITIONS WILL TREND TO VFR THROUGH THE MORNING HOURS. EXTENDED AVIATION DISCUSSION... EXPECT MAINLY VFR CONDITIONS SUNDAY AFTERNOON INTO MONDAY AS HIGH PRESSURE SPREADS ACROSS THE FORECAST AREA. NEXT COLD FRONT IS FORECAST TO ARRIVE WITH POTENTIAL FOR SHOWERS MONDAY EVENING/OVERNIGHT. TIMING OF SHOWERS WITH THIS FRONT A BIT UNCERTAIN BUT COULD SEE PERIODS OF MVFR MONDAY NIGHT AND MAINLY ALONG THE WESTERN SLOPES TUESDAY...OTHERWISE VFR ACROSS THE EAST. ANOTHER DISTURBANCE SLIDING IN FROM THE NW MAY BRING THE NEXT ROUND OF SUB-VFR CONDITIONS ESPCLY ACROSS THE MOUNTAINS ON WEDNESDAY INTO THURSDAY. && .HYDROLOGY... AS OF 300 PM EDT SATURDAY... A SWATH OF HEAVIER SHOWERS AND THUNDERSTORMS MOVED ACROSS MUCH OF THE REGION OVERNIGHT RESULTING IN SPOTS RECEIVING BETWEEN 1 AND 3 INCHES OF RAIN. THE MOST CONCENTRATED AREA OF HEAVY RAIN WAS ALONG/WEST OF THE BLUE RIDGE ESPECIALLY FROM ASHE COUNTY NORTH ACROSS THE MOUNTAIN EMPIRE REGION INTO SOUTHEAST WEST VIRGINIA AS WELL AS THE VIRGINIA HIGHLANDS. THE POTENTIAL EXISTS THIS AFTERNOON FOR LINES OR CLUSTERS OF STORMS TO MOVE INTO OR DEVELOP OVER THE MOUNTAINS WHERE FLASH FLOOD GUIDANCE IS THE LOWEST. RAINFALL OF 1 TO PERHAPS AS MUCH AS 3 INCHES COULD OCCUR WITH VERY HEAVY RAINFALL RATES EXCEEDING 2 INCHES AT HOUR AT TIMES. GIVEN THAT SOME AREAS ARE NOW MORE PRIMED FOR FLOODING THE FLASH FLOOD WATCH WILL CONTINUE THROUGH LATE THIS AFTERNOON FOR MANY COUNTIES ALONG AND WEST OF THE BLUE RIDGE. THIS EXCLUDES PARTS OF THE NEW RIVER VALLEY AND NORTHWEST NORTH CAROLINA WHERE EARLIER RAINFALL WAS NOT AS HEAVY. && .CLIMATE... AS OF 300 PM EDT FRIDAY... JUNE 29TH RECORD LOWS BLACKSBURG...42 IN 1974 BLUEFIELD....52 IN 1970 DANVILLE.....54 IN 1968 LEWISBURG....49 IN 1981 LYNCHBURG....51 IN 1970 ROANOKE......44 IN 1919 && .EQUIPMENT... THE NOAA WEATHER RADIO IN LYNCHBURG...BROADCASTING ON A FREQUENCY OF 162.550 MHZ...IS NOW OPERATING AT FULL CAPACITY. THE NOAA WEATHER RADIO IN HINTON WV...BROADCASTING ON A FREQUENCY OF 162.425 MHZ...IS OFF THE AIR DUE TO A TELCO PROBLEM. THIRD PARTY TECHNICIANS ARE CURRENTLY WORKING ON THE COMMUNICATION ISSUE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...FLASH FLOOD WATCH UNTIL 6 PM EDT THIS EVENING FOR VAZ007- 009>015-018>020-022>024-034-035. WIND ADVISORY FROM 4 AM TO 4 PM EDT SUNDAY FOR VAZ007-009>020- 022>024-034-035. NC...FLASH FLOOD WATCH UNTIL 6 PM EDT THIS EVENING FOR NCZ001. WIND ADVISORY FROM 4 AM TO 4 PM EDT SUNDAY FOR NCZ001-002-018. WV...FLASH FLOOD WATCH UNTIL 6 PM EDT THIS EVENING FOR WVZ042>044- 507-508. WIND ADVISORY FROM 4 AM TO 4 PM EDT SUNDAY FOR WVZ042>044-507- 508. && $$ SYNOPSIS...DS NEAR TERM...DS SHORT TERM...RAB LONG TERM...RAB AVIATION...DS HYDROLOGY...DS CLIMATE...DS EQUIPMENT...DS

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