Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 062007 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 407 PM EDT WED MAY 6 2015 .SYNOPSIS... A BACKDOOR COLD FRONT WILL SLOWLY MAKE ITS WAY INTO AND THROUGH OUR REGION TONIGHT AND THURSDAY...ALL WHILE HIGH PRESSURE CONTINUES ITS GRIP ON THE SOUTHEAST UNITED STATES. A SLOW MOVING AREA OF LOW PRESSURE WILL MOVE NORTH ALONG THE COAST OF THE CAROLINAS THIS WEEKEND. A COLD FRONT WILL MOVE ACROSS THE AREA ON MONDAY OR TUESDAY OF NEXT WEEK. && .NEAR TERM /THROUGH THURSDAY NIGHT/... AS OF 330 PM EDT WEDNESDAY... WHILE STILL MAINLY ISOLATED...OF THE PAST THREE DAYS...WE ARE SEEING THE BEST COVERAGE OF SHOWERS...AND A FEW THUNDERSTORMS...TODAY. WE HAVE BOTH DAYTIME HEATING AND THE APPROACH OF A BACKDOOR COLD FRONT TO THANK. GIVEN THAT THE ACTIVITY IS MORE THAN DIURNALLY DRIVEN...EXPECT THE SHOWERS TO CONTINUE THROUGH THE EVENING HOURS...ALTHOUGH THE TREND WILL BE FOR A GRADUAL DECREASE IN COVERAGE. THE LAST OF THE SHOWERS ARE EXPECTED TO END AROUND 200 OR 300 AM ON THURSDAY ACROSS THE ALLEGHANY HIGHLANDS....EAST TO NEAR LYNCHBURG. WHILE CONFIDENCE IS THIS OCCURRING IS NOT STAGGERING...WE WILL NEED TO WATCH NORTHERN AND EASTERN PARTS OF THE REGION TONIGHT FOR AN INCREASE IN LOW LEVEL CLOUD COVER ON THE BACKSIDE OF THE ADVANCING FROM. SOME GUIDANCE IS HINTING AT THIS TO OCCUR. OUR CLOUD COVER FORECAST WILL ALLOW FOR THIS POTENTIAL TO SOME DEGREE WITH THE GREATEST COVERAGE OF CLOUDS TOWARDS SUNRISE THURSDAY BEING NORTH AND EAST OF LYNCHBURG. PATCHY FOG WILL ALSO BE POSSIBLE TO A GREATER DEGREE LATE TONIGHT AND EARLY THURSDAY AS COMPARED TO THIS MORNING....GIVEN MORE AREAS WILL HAVE RECEIVED SOME PRECIPITATION TODAY...LIGHT WINDS...AND INCREASED LOW LEVEL MOISTURE BEHIND THE BACKDOOR FRONT. LOW TEMPERATURES WILL RANGE FROM THE MID 50S TO NEAR 60 DEGREES OVER MUCH OF THE REGION. THE HIGHER ELEVATIONS WILL BE COOLER WITH LOWS AROUND 50. ON THURSDAY...THE BACKDOOR FRONT IS EXPECTED TO TAKE UP RESIDENCY OVER THE FAR WESTERN PORTION OF THE AREA. LOOK FOR THE FOCUS FOR SHOWER AND THUNDERSTORM DEVELOP TO SHIFT WEST FROM THE BLUE RIDGE...TO BE IN THE VICINITY OF THE FRONT. COVERAGE WILL BE SCATTERED NEAR THE FRONT AND ISOLATED EAST TO THE CREST OF THE BLUERIDGE. HIGHS WILL ONLY BE SLIGHTLY COOLER THAN CONDITIONS OF TODAY. HIGHS WILL RANGE FROM THE MID 70S TO THE UPPER 70S ACROSS THE MOUNTAINS WITH UPPER 70S TO AROUND 80 ACROSS THE PIEDMONT. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 345 PM EDT WEDNESDAY... SHORT AND LONG TERM FORECAST COMPLICATED BY MOVEMENT OF POTENTIAL TROPICAL STORM ALONG THE SOUTHEAST U.S. COAST. LATEST NHC OUTLOOK HAS A 60 PERCENT CHANCE OF THIS DEVELOPING INTO A TROPICAL/SUBTROPICAL SYSTEM WITHIN THE NEXT 48 HOURS SOMEWHERE OFF THE SC/GA COAST. AS WITH PREVIOUS MODEL RUNS...THE GFS REMAINS THE MOST AGGRESSIVE IN BRINGING THIS SYSTEM INTO THE CENTRAL AND EASTERN PORTIONS OF OUR CWA UNDERNEATH A BROAD UPPER RIDGE ACROSS THE EASTERN U.S. AND WEAK STEERING CURRENTS. HOWEVER...ALL MODELS INDICATE THAT WE WILL SEE AT LEAST SOME EFFECTS IN THE WAY OF CLOUDS AND AT LEAST LIMITED MOISTURE INTO THE EASTERN SECTIONS WITHIN THIS TIME FRAME AS A RESULT OF THIS SYSTEM. TO THE WEST...A BROAD UPPER TROUGH PERSISTS IN THE WESTERN U.S. AND IS EXPECTED TO REMAIN WELL WEST OF THE CWA THROUGH THIS TIME FRAME. MEANWHILE...WHATEVER IS LEFT OF THE BACKDOOR FRONT WOULD APPEAR TO BE ACROSS EITHER FAR SW VA INTO NW NC OR BACK IN EASTERN TN...GENERALLY BEING ABSORBED INTO THE LARGE SCALE CIRCULATION AROUND THE TROPICAL SYSTEM. FOCUS FOR SHOWERS/THUNDERSTORMS SHOULD BE EITHER IN THE FAR WEST...GENERALLY WEST OF I-77...OR PERHAPS NEAR OUTERBANDS OF THE TROPICAL SYSTEM IN AREAS OF DIFFERENTIAL HEATING. CANNOT JUSTIFY ANY MORE THAN CHANCE POPS AT THIS POINT. WITH RESPECT TO THUNDER...INSTABILITY IS LIMITED AND GENERALLY WEST OF THE REGION ACROSS THE OH/TN VALLEY. CLOUDS AND SHOWERS ASSOCIATED WITH THE TROPICAL SYSTEM WILL MINIMIZE INSTABILITY ACROSS THE PIEDMONT...SO OVERALL THUNDER THROUGH SATURDAY WILL BE LIMITED. TEMPERATURES WILL BE QUITE WARM THROUGH THE PERIOD...BUT MAY BE HELD DOWN SOMEWHAT ACROSS THE PIEDMONT PENDING CLOUD COVER ASSOCIATED WITH THE TROPICAL SYSTEM. GENERALLY LOOK FOR LOWS IN THE 50S AND 60S WITH HIGHS IN THE 70S TO LOWER 80S...OVERALL ABOUT 10 DEGREES ABOVE NORMAL. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 400 PM EDT WEDNESDAY... SUNDAY APPEARS TO LARGELY BE A REPEAT OF SATURDAY...WITH EFFECTS OF REMNANT TROPICAL SYSTEM ACROSS THE EAST...AND THE FRONTAL SYSTEM STILL WELL AT BAY TO THE WEST. MONDAY APPEARS TO BE THE BEST DAY FOR WIDESPREAD CONVECTION AND ANY THREAT OF SEVERE...ALBEIT THAT REMAINS LOW...AS THE FRONTAL SYSTEM AND ASSOCIATED UPPER TROUGH PUSH THROUGH THE AREA. GFS APPEARS TOO QUICK WITH PUSHING THE FRONT SOUTH OF THE AREA AND BRINGING MUCH COOLER/DRIER AIR INTO THE REGION FROM THE NORTH. HAVE LEANED MORE TOWARD THE ECMWF SOLUTION OF SLOWING THIS DOWN...HOLDING ONTO LOW CHANCES FOR CONVECTION ACROSS THE SOUTHERN COUNTIES INTO TUE. MUCH OF THE UPPER SUPPORT ON MONDAY TRACKS EITHER NORTH OR SOUTH OF THE REGION...AND THERE STILL REMAIN QUESTIONS AS TO HOW MUCH SUBSIDENCE OR INTERACTION WITH THE FRONT THE REMNANT TROPICAL SYSTEM WILL HAVE AT THAT POINT. HAVE NOT ADVERTISED ANY LIKELY POPS AT THIS POINT...STICKING WITH MID TO HIGH RANGE CHANCE POPS. TEMPERATURES SHOULD REMAIN WELL ABOVE NORMAL SUNDAY AND MONDAY...TRENDING MORE TOWARD NORTH READINGS TUE-WED. ANOTHER STRONGER SYSTEM APPEARS DESTINED TO APPROACH FROM THE SOUTHWEST TOWARD THE VERY END OF THE PERIOD...BUT FOR NOW HAVE JUST ADVERTISED SLIGHT CHC POPS NORTHWEST NC. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... AS OF 135 PM EDT TUESDAY... FORECAST CONFIDENCE IS MODERATE TO HIGH THROUGH MIDDAY THURSDAY. ISOLATED TO SCATTERED SHOWERS ARE DEVELOPING IN AREAS ALONG AND WEST OF THE BLUE RIDGE...IN CONJUNCTION WITH HEATING OF THE DAY AND THE APPROACH A BACKDOOR COLD FRONT. CIGS ARE MAINLY VFR ACROSS THE AREA. BRIEF...LOCALIZED SUB-VFR CONDITIONS WILL BE POSSIBLE UNDER THE HEAVIER SHOWERS/STORMS. THE SHOWERS AND STORMS WILL DISSIPATE AFTER SUNSET. OVERNIGHT...THE BACKDOOR COLD FRONT WILL MAKE PROGRESS INTO THE REGION AND BRING LOW LEVEL WINDS AROUND TO THE NE-E. SOME GUIDANCE IS ALLOWING FOR THE POTENTIAL FOR SOME MVFR CIGS TO ARRIVE IN MAINLY NORTH AND EASTERN PARTS OF THE AREA. PATCHY LIGHT FOG WILL ALSO BE POSSIBLE...ESPECIALLY IN AREAS THAT RECEIVED RAIN TODAY...AND ALSO IN SOME OF THE MOUNTAIN AND RIVER VALLEYS. ON THURSDAY...ISOLATED TO SCATTERED SHOWER AND STORM DEVELOPMENT WILL AGAIN BE POSSIBLE ALONG THE LEADING EDGE OF THE BACKDOOR FRONT AND DURING THE PEAK HEATING OF THE DAY. THIS WOULD PLACE THE GREATEST COVERAGE ACROSS SOUTHEAST WEST VIRGINIA...SOUTH INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA. FORECAST CONFIDENCE THURSDAY AFTERNOON THROUGH SATURDAY IS MODERATE. AFTERNOON AND EARLY EVENING SHOWERS AND STORMS WILL BE COMMON THROUGH SATURDAY...BUT THE TREND FOR THE AXIS OF BEST COVERAGE WILL SLOWLY WORK ITS WAY WEST OF THE REGION. CONDITIONS WILL MAINLY BE VFR EXCEPT FOR SOME LATE NIGHT AND EARLY MORNING PATCHY LIGHT FOG AND SUB-VERSION PATCHY MVFR CLOUDS. FORECAST CONFIDENCE SATURDAY NIGHT INTO MONDAY IS LOW. MODEL GUIDANCE IS STILL SHOWING A DECENT AMOUNT OF VARIABILITY IN THEIR SOLUTIONS REGARDING THE ROUTE A SLOW MOVING UPPER LOW ALONG THE COAST OF THE CAROLINAS WILL TAKE LATE THIS WEEKEND INTO EARLY NEXT WEEK. ACCORDINGLY...THE TIMING AND APPROACH OF A COLD FRONT FROM THE MID-MISSISSIPPI VALLEY WILL BE IMPACTED BY THE POSITION OF THE LOW AS WELL. A CONSENSUS FORECAST PLACES INCREASING COVERAGE OF SHOWERS AND STORMS OVER THE AREA DURING THIS PERIOD WITH A MIX OF MVFR AND VFR CONDITIONS WITH THE BEST COVERAGE ON MONDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...DS SHORT TERM...RAB LONG TERM...RAB AVIATION...DS

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