Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 271702 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 102 PM EDT SAT JUN 27 2015 .SYNOPSIS... A WARM FRONT WILL LIFT NORTH OF THE AREA BY THIS AFTERNOON AHEAD OF A DEEP LOW PRESSURE SYSTEM THAT WILL SLIDE UP THE OHIO RIVER VALLEY BY LATE IN THE DAY. THIS WILL BRING ADDITIONAL ROUNDS OF SHOWERS AND STORMS TO THE REGION INTO THIS EVENING. A STRONG COLD FRONT WILL MOVE ACROSS THE AREA TONIGHT...RESULTING IN GUSTY NORTHWEST WINDS AND UNSEASONABLY COOL TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1255 PM EDT SATURDAY... ACROSS THE REGION KFCX 88D RADAR CONTINUE TO SHOW TWO AREAS WHERE PRECIPITATION THE NEXT FEW HOURS WILL BE THE MOST PLENTIFUL. SOME PATCHY LIGHT TO MODERATE RAIN WAS SPREADING NORTHEAST OUT OF TENNESSEE/KENTUCKY INTO OUR REGION. THE BULK OF THIS ACTIVITY WILL BE ALONG AND WEST OF A BOONE NC...BLACKSBURG VA...LEWISBURG WV LINE THROUGH THE MID AFTERNOON. BY THE LATE AFTERNOON...THIS ACTIVITY WILL HAVE REACHED CENTRAL PORTIONS OF THE FORECAST AREA. AS MORE SURFACE HEATING TAKES PLACE...THERE THE TREND WILL BE FOR STRONGER SHOWER AND THUNDERSTORM DEVELOPMENT. THE OTHER REGION OF PRECIPITATION ACTIVITY IS IN THE FORM OF ISOLATED TO SCATTERED SHOWERS AND STORMS THAT ARE FORMING ACROSS EASTERN PARTS OF SOUTHSIDE VIRGINIA...NORTH INTO THE JAMES RIVER BASIN. THIS ACTIVITY IS EXPECTED TO CONTINUE WITHIN THIS REGION...AND ALSO EXPAND IN COVERAGE. IN BETWEEN THESE TWO AREAS...VERY LITTLE IN THE WAY OF PRECIPITATIONS WAS OCCURRING. WHILE THIS WILL CONTINUE TO BE THE TREND...THERE ALSO WILL BE TREND FOR FOR MORE DEVELOPMENT THAN THE CURRENT SCENARIO. HAVE MADE APPROPRIATE CHANGES TO THE POP AND WEATHER GRIDS TO REFLECT THESE THREE AREAS AND EXPECTED TRENDS THROUGH THE REMAINDER OF THE AFTERNOON. NO CHANGES TO THE HIGH TEMPERATURE FORECAST...BUT HAVE ADJUSTED HOURLY TEMPERATURES TO BETTER FIT THE CURRENT CONDITIONS AND EXPECTED TRENDS. AS OF 955 AM EDT SATURDAY... OUR FORECAST UPDATE THIS MORNING REFLECT AN ADJUSTMENT TO THE PLACEMENT AND TIMING OF PRECIPITATION ACROSS...OR EXPECTED TO MOVE INTO THE REGION. LITTLE IF ANY PRECIPITATION IS CURRENTLY FALLING ACROSS THE REGION...ALTHOUGH A GENEROUS AREA HAS JUST EXITED THE NORTH...AND ANOTHER REGION IS ABOUT TO ENTER FROM THE SOUTHWEST. THE UPDATE WILL REFLECT A LULL IN THE ACTIVITY...ESPECIALLY IN THE EAST...UNTIL ADDITIONAL PRECIPITATION CAN PROGRESS INTO THE AREA FROM THE SOUTHWEST...OR DEVELOP ACROSS THE AREA AS WE HEAD INTO THE AFTERNOON. NO OTHER NOTABLE CHANGES AT THIS TIME. AS OF 240 AM EDT SATURDAY... SWATH OF HEAVIER SHRA/TSRA JUST NORTH OF THE SURFACE WARM FRONT AND ALONG THE LOW LEVEL THETA-E GRADIENT CONTINUES TO WORK OFF TO THE NE AND SHOULD EXIT THE FAR NORTHERN COUNTIES AROUND SUNRISE. THIS WILL BRING A BRIEF LULL IN CONVECTION EARLY THIS MORNING AS THE WARM FRONT STARTS TO LIFT NORTH AHEAD OF THE UPSTREAM COLD FRONT THAT WONT MAKE IT INTO THE MOUNTAINS UNTIL EARLY THIS EVENING. THUS WILL GRADUALLY TRIM BACK POPS TO MOSTLY CHANCE TO START THE MORNING PER THE LATEST HRRR BEFORE HEATING COMMENCES AND STARTS TO RECHARGE THINGS AHEAD OF THE BOUNDARY THIS AFTERNOON. LATEST GUIDANCE REMAINS CONSISTENT IN BRINGING ADDED BANDS OF DEEPER CONVECTION INTO THE WEST BY AFTERNOON BEFORE THINGS LIKELY CONSOLIDATE HEADING OFF THE BLUE RIDGE TOWARD MID AFTERNOON IF NOT SOONER. HOWEVER BEST SUPPORT INCLUDING WINDS ALOFT WILL PASS TO THE NORTH WITH OVERALL BEST SHEAR ENDING UP ALONG THE WARM FRONT OVER NORTHERN VA. ALSO SIMILAR TO FRIDAY...WILL INIT WITH LITTLE INSTABILITY PER HEAVY RAIN FROM OVERNIGHT WHICH LOOKS TO LEAD TO SOMEWHAT WEAKER LAPSES/CAPES THIS AFTERNOON AS SEEN VIA THE LATEST NAM SHOWING ONLY 1K J/KG VALUES WEST AND PERHAPS 2K OUT EAST PENDING THE DEGREE OF HEATING BEFORE THINGS REDEVELOP. THIS SUPPORTS THE BEST SEVERE THREAT OUT EAST FOR MAINLY DAMAGING WINDS PER HEAVY PRECIP LOADING AS SEEING LITTLE DRY AIR ALOFT OFF FORECAST SOUNDINGS. OTRW SPEED OF BANDS/CLUSTERS SHOULD BE A BIT FASTER GIVEN THE 30-40 KT SW JET ALOFT. HOWEVER SINCE ALREADY HAVE A FLASH FLOOD WATCH IN PLACE WILL CLIP OFF A FEW COUNTIES ACROSS THE SOUTH WHERE RAINFALL HAS BEEN LESS AND ADD A COUPLE ALONG THE BLUE RIDGE UP NORTH. ALSO PLAN TO EXTEND THE WATCH OUT UNTIL 6 PM TO COVER HEAVY RAIN WITH THE FRONT AND MATCH UP WITH BORDERING OFFICES FOR NOW. THEREFORE KEPT LIKELY/CAT POPS THIS AFTERNOON WITH ONLY A SLOW EXODUS OF HEAVIER SHRA TO THE EAST AROUND 00Z WITH CHANCES LINGERING WEST UNTIL FROPA THIS EVENING. HIGH TEMPS A BIT COOLER GIVEN CLOUDS AROUND WITH MOSTLY 70S TO NEAR 80 WEST AND LOW/MID 80S EAST PROVIDED SOME SUN. COLD FRONT PUNCHES TO THE EAST OVERNIGHT ALLOWING A GOOD DRY SLOT TO WORK EAST AIDED BY 40 KTS AT 85H AND STRONG COOL ADVECTION UNDER THE PASSING UPPER TROUGH. THIS SHOULD BRING AN END TO MOST SHOWERS AFTER MIDNIGHT WITH ONLY SOME RESIDUAL UPSLOPE FLOW LIGHT SHOWERS POSSIBLE NW THROUGH DAYBREAK. WINDS LOOK GUSTY GIVEN THE ABRUPT 85H COOLING BUT BELOW ADVISORY LEVELS PER ONLY WEAK SUBSIDENCE. TEMPS WILL CRASH BACK INTO THE 50S OVER THE WEST WHERE WILL GET SOME CLEARING OUTSIDE OF THE UPSLOPE COUNTIES...WHILE EXPECT LOWS CLOSER TO 60-65 OUT EAST WHERE THE 85H FRONT WONT CROSS UNTIL LATE.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 315 AM EDT SATURDAY... GUSTY NW WINDS TO CONTINUE INTO SUNDAY UNDER A LINGERING GRADIENT BETWEEN THE UPPER LOW PASSING ACROSS NEW ENGLAND AND WEAK HIGH PRESSURE BUILDING IN FROM THE WEST. SHOULD AGAIN SEE SOME GUSTS TO 40-45 MPH MOUNTAINS MAINLY EARLY BEFORE SPEEDS DIMINISH SOME IN THE AFTERNOON. DOWNSLOPE DRYING AND SUBSIDENCE SHOULD LEAD TO CLEARING SKIES IN ALL BUT THE UPSLOPE AREAS WHERE WILL NEED TO KEEP A LOW END POP FOR ISOLATED SHOWERS NW INTO SUNDAY EVENING BEFORE THINGS DRY OUT. TEMPERATURES WILL CONTINUE TO TREND COOLER INTO SUNDAY. HIGHS ON SUNDAY WILL RANGE FROM AROUND 70 TO THE LOWER 70S ACROSS THE MOUNTAINS TO THE UPPER 70S TO AROUND 80 ACROSS THE PIEDMONT. DRY AND COOL HIGH PRESSURE WILL SETTLE OVER THE REGION ON SUNDAY NIGHT. EXPECT NO PRECIPITATION WITH BELOW NORMAL TEMPERATURES. LOWS WILL RANGE FROM THE LOW TO MID 50S ACROSS THE MOUNTAINS AND PERHAPS A FEW 40S DEEPER VALLEYS...WITH UPPER 50S ACROSS THE PIEDMONT. WHILE NO RECORD LOW TEMPERATURES ARE FORECAST...A FEW LOCATIONS WILL FALL TO READINGS WITHIN FIVE DEGREES OF RECORD LOWS. SEE THE CLIMATE SECTION OF THIS DISCUSSION FOR DETAILS. ON MONDAY...THE CENTER OF THE SURFACE HIGH PRESSURE WILL PROGRESS EASTWARD IN ADVANCE OF OUR NEXT GREAT LAKES SHORTWAVE TROUGH. EXPECT A RETURN OF A SOUTHERLY COMPONENT OF THE LOW LEVEL WINDS AND INCREASING DEW POINTS AND TEMPERATURES. WHILE NO PRECIPITATION IS FORECAST FOR THE MORNING...SOME ISOLATED SHOWERS MAY DEVELOP ACROSS THE FAR SW DURING THE AFTERNOON. HIGH TEMPERATURES WILL AVERAGE 5 TO 7 DEGREES MILDER THAN THOSE OF SUNDAY. ANTICIPATE UPPER 70S TO AROUND 80 IN THE MOUNTAINS AND LOW TO MID 80S ACROSS THE PIEDMONT. ON MONDAY NIGHT...THE TROUGH AXIS OF THE GREAT LAKES SYSTEM WILL START PROGRESSING THROUGH THE OHIO VALLEY. LOOK FOR SHOWERS AND STORMS TO EXPAND IN COVERAGE ACROSS THE WESTERN PARTS OF THE AREA. STILL LITTLE OR NO COVERAGE IS ANTICIPATED FOR AREAS EAST OF THE CREST OF THE BLUE RIDGE. LOW TEMPERATURES WILL RANGE FROM THE UPPER 50S TO AROUND 60 ACROSS THE MOUNTAINS TO THE LOWER 60S ACROSS THE PIEDMONT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 320 PM EDT FRIDAY... THIS PORTION OF THE FORECAST PERIOD IS EXPECTED TO BE ONE WITH SCATTERED SHOWERS AND STORMS ACROSS THE AREA EACH DAY AND NIGHT. THE AXIS OF A SHORTWAVE TROUGH WILL MOVE THROUGH THE REGION BY MIDDAY TUESDAY. THE COLD FRONT ASSOCIATED WITH THIS SYSTEM IS EXPECTED TO STALL OVER...OR JUST SOUTH OF THE AREA...AND TAKE ON A NW-SE ORIENTATION. THROUGH FRIDAY...LITTLE MOVEMENT OF THIS FRONT IS EXPECTED. THE COMBINATION OF DAYTIME HEATING...AND THE POTENTIAL FOR ADDITIONAL WAVES OF ENERGY MOVING SOUTHEAST ALONG THIS FEATURE WILL BE THE SOURCE OF THE FORECAST SCATTERED SHOWERS AND SOME STORMS. HIGH TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL RANGE FROM THE UPPER 70S TO AROUND 80 ACROSS THE MOUNTAINS AND MID TO UPPER 80S ACROSS THE PIEDMONT. LOW TEMPERATURES WILL MAINLY BE IN THE LOWER 60S ACROSS THE MOUNTAINS AND UPPER 60S ACROSS THE PIEDMONT. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 705 AM EDT SATURDAY... SHOWERS HAVE REDEVELOPED ACROSS THE FAR WEST THIS MORNING AND EXPECT THESE TO PERSIST AROUND KBLF/KLWB THROUGH AT LEAST MID MORNING RESULTING IN MVFR CIGS AND PERHAPS MVFR VSBYS AT TIMES. SOME OF THESE SHOWERS LIKELY TO MOVE EAST TOWARD KBCB/KROA BEFORE SEEING ADDED REDEVELOPMENT OF STRONGER SHRA/TSRA TAKE SHAPE THIS AFTERNOON. OTRW EVEN WITHOUT SHOWERS...LOOKING AT LOW CONDITIONS OUTSIDE OF KDAN TO INIT WITH WIDESPREAD MVFR/IFR CIGS IN THE WAKE OF THE HEAVIER RAINFALL FROM OVERNIGHT. THINK SHOULD SEE SOME SLOW IMPROVEMENT TO CIGS THROUGH THE MORNING BUT ADDED SHRA MIGHT HOLD AT LEAST MVFR CONDITIONS IN PLACE LONGER SO SLOWED DOWN IMPROVEMENT UNTIL LATE MORNING/EARLY AFTERNOON. OTRW PRIMARY CONCERN THIS AFTERNOON IS WITH THE STRONG FRONTAL PASSAGE WHICH IS FORECAST BY ALL MODELS TO OCCUR LATER TODAY INTO THIS EVENING WITH 40-50KT WESTERLY WINDS 3KFT AGL DEVELOPING BEHIND THE FRONT LATE TONIGHT. ANTICIPATING ANOTHER BKN LINE OF SHOWERS/TSTMS TO ACCOMPANY THE FRONT LATER THIS AFTERNOON...FOLLOWED BY PARTIAL CLEARING TONIGHT WITH GUSTY WESTERLY WINDS IN ALL EXCEPT THE UPSLOPE AREAS WHERE PERIODS OF MVFR CIGS LIKELY TO LINGER. GIVEN UNCERTAINTY WITH TIMING OF WHEN BANDS MIGHT CROSS WILL LEAVE IN AN OVERALL VICINITY MENTION THIS AFTERNOON AFTER MORNING SHRA EXIT FOR NOW. EXPECT MAINLY VFR CONDITIONS SUNDAY INTO MONDAY...HIGH PRESSURE SPREADING 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. && .HYDROLOGY... AS OF 655 AM 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. SHOWERS ARE EXPECTED TO REDEVELOP OVER THE MOUNTAINS THIS MORNING AND THEN SPREAD EAST WHILE STRENGTHENING AHEAD OF A STRONG COLD FRONT THAT WILL ARRIVE THIS EVENING. THE POTENTIAL EXISTS FOR LINES OR CLUSTERS OF STORMS TO DEVELOP AND OVER THE MOUNTAINS WHERE FLASH FLOOD GUIDANCE IS NOW 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 EARLIER FLASH FLOOD WATCH WAS EXTENDED/EXPANDED 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 OPERATING ON THE SECONDARY TRANSMITTER. TECHNICIANS CONTINUE TO WORK ON THE ISSUE AND HAVE ADVISED THAT BOTH TRANSMITTERS WONT BE FULLY OPERATIONAL UNTIL AT LEAST SUNDAY. 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. NC...FLASH FLOOD WATCH UNTIL 6 PM EDT THIS EVENING FOR NCZ001. WV...FLASH FLOOD WATCH UNTIL 6 PM EDT THIS EVENING FOR WVZ042>044- 507-508. && $$ SYNOPSIS...JH/NF NEAR TERM...DS/JH SHORT TERM...DS/JH LONG TERM...DS/WP AVIATION...JH/PM HYDROLOGY...JH CLIMATE... EQUIPMENT...PM

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