Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 301735 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 135 PM EDT SAT MAY 30 2015 .SYNOPSIS... HIGH PRESSURE OFFSHORE WILL MAINTAIN A VERY WARM AND HUMID AIR MASS ACROSS THE REGION TODAY INTO SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST LATE IN THE WEEKEND...BEFORE PUSHING SOUTH OF THE AREA BY MONDAY...RESULTING IN MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LATER SUNDAY INTO MONDAY AFTERNOON. COOLER WEATHER UNDER HIGH PRESSURE WILL BUILD IN BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1250 PM EDT SATURDAY... CONVECTIVE INITIATION AND LATEST RADAR TRENDS SHOWED DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE BLUE RIDGE NORTH OF ROANOKE AND WEST OF A LINE FROM BUENA VISTA TO BLUEFIELD. HAVE ADJUSTED PROBABILITY OF PRECIPITATION TO HAVE HIGHEST PERCENTAGES IN THAT AREA. LITTLE CHANGE NEEDED TO TEMPERATURE FORECAST FOR THE REST OF THE DAY. THE LATEST NCAR ENSEMBLE AND HRRR BUT STILL SHOWED NO MORE THAN CHANCE POPS AT BEST. ELSEWHERE CANT TOTALLY RULE OUT AT LEAST ISOLATED SHRA/TSRA PER HEATING...DECENT INSTABILITY...AND HIGH 85H THETA-E WITH BEST CHANCES MOUNTAINS WHERE AIDED BY OROGRAPHICS ESPCLY BLUE RIDGE. SHOULD BE ONE OF THE WARMEST DAYS SO FAR THIS SEASON GIVEN A WARM START AND LESS EXPECTED CLOUDS/TSRA THIS AFTERNOON. AGAIN APPEARS MOS A BIT COOL AS SEEN OVER THE PAST COUPLE OF DAYS AS THICKNESS SUGGESTS HIGHS CLOSE TO 90 SE...WITH LOW/MID 80S ELSEWHERE OUTSIDE OF THE HIGHEST ELEVATIONS. ANY EVENING CONVECTION MAY LINGER ESPCLY MOUNTAINS AN HOUR OR TWO AFTER SUNSET BEFORE LOSS OF HEATING AND LACK OF FORCING CAUSE SHOWERS TO FADE SO WILL KEEP SOME LOW POPS GOING THIS EVENING MAINLY FAR WEST. UPSTREAM PRE-FRONTAL SHRA/TSRA WILL THEN BE THE MAIN CONCERN OVERNIGHT BUT APPEARS MUCH OF THIS TOO FAR WEST TO REACH THE REGION BY DAYBREAK SUNDAY. HOWEVER RETURN OF DEEPER MOISTURE AHEAD OF THE TROUGH/FRONT AS SEEN IN MODEL PWATS LATE SUPPORTS INCLUDING SOME ISOLATED TO LOW CHANCE POPS MAINLY WESTERN THIRD LATE. OTHERWISE MAINLY PC WITH ADDED PATCHY FOG BY MORNING. TEMPS TO REMAIN ON THE WARM/MUGGY SIDE WITH MOST SPOTS ONLY FALLING INTO THE 60-66 RANGE. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... AS OF 245 AM EDT SATURDAY THE MEDIUM RANGE MODELS ARE ALL IN CONSENSUS THAT A SFC COLD FRONT.. ASSOCIATED WITH AN UPPER TROUGH MOVING THROUGH THE EASTERN GREAT LAKES INTO NEW ENGLAND...MOVES THROUGH OUR FORECAST AREA MONDAY. HOWEVER...THE MORE NOTICEABLE DRIER AIR AND COOLER TEMPS ARRIVE MONDAY NIGHT/EARLY TUESDAY ONCE SOUTHERN STREAM ENERGY AND ASSOCIATED SFC WAVE LIFT EAST. THE FORECAST AREA WILL REMAIN FIRMLY ENTRENCHED IN THE WARM SECTOR SUNDAY. WHILE INSTABILITY WILL INCREASE AS HIGHER PWAT AIR RETURNS...BEST SHEAR AND UPPER LEVEL DYNAMICS REMAIN NORTH AND WEST OF THE FORECAST AREA THROUGH SUNDAY. WHILE AN ISOLATED SEVERE STORM IS POSSIBLE...GREATER CONCERN MAY BE WITH LOCALLY HEAVY DOWNPOURS. WITH THE SLOWER ARRIVAL OF THE FRONT...PUSHED UP TEMPS A COUPLE OF DEGREES FOR HIGHS...ESPECIALLY IN THE EAST. KEPT POPS GOING AFTER SUNDOWN SUNDAY WITH FORCING FROM SFC BOUNDARY MOVING INTO THE AREA. WENT ABOVE GUIDANCE FOR LOWS SUNDAY NIGHT DUE TO CLOUDS AND SOME MIXING. PRECIPITATION MAY BE MORE WIDESPREAD MONDAY...ESPECIALLY IN THE SOUTHERN HALF OF THE FORECAST AREA...AS SFC BOUNDARY SLOWS SOMEWHERE IN THE EASTERN PORTION OF THE FORECAST AREA DUE TO A SFC WAVE FROM SOUTHERN STREAM ENERGY DEVELOPING IN NC. EXPECT MORE CLOUD COVER AND SLIGHTLY COOLER TEMPS ON MONDAY...AS A RESULT...LOWER INSTABILITY. THE EXCEPTION WOULD BE IN ADVANCE OF THE FRONT...IN THE FAR EASTERN PORTION OF THE FORECAST AREA WHERE AN ISOLATED SEVERE STORM CANNOT BE RULED OUT. DRIER/COOLER AIR FINALLY SURGES INTO THE FORECAST AREA MONDAY NIGHT AND TUESDAY. LEANED TOWARD THE COOLER GUIDANCE VALUES DURING THIS PERIOD. WHILE THE SFC BOUNDARY PUSHES SOUTH OF THE FORECAST AREA BY TUESDAY...850MB THETA-E AXIS LINGERS IN NC AND SOUTHERN VA AND WEAK OVERRUNNING WILL KEEP THE THREAT FOR SHOWERS FOR THIS AREA. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... AS OF 245 PM EDT FRIDAY... THE COLD FRONT WILL WASH OUT OVER OR JUST SOUTH OF THE AREA BY TUESDAY AFTERNOON. AFTER THIS POINT...THE REGION WILL START TO TRANSITION BACK A SOUTHERLY FLOW PATTERN AS A LOW/TROUGH DEVELOPS ACROSS THE LOWER MISSISSIPPI RIVER VALLEY...AND HIGH PRESSURE BECOMES CENTERED AGAIN OFF THE COAST OF THE CAROLINAS. DAYTIME HEATING ALONG WITH PIECES OF ENERGY EJECTING OFF THE LOWER MISSISSIPPI VALLEY LOW WILL HELP YIELD INCREASING CHANCE OF SHOWERS AND STORMS AGAIN BY THURSDAY INTO FRIDAY. TEMPERATURES WILL ALSO START TO TREND MILDER THURSDAY INTO FRIDAY. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 125 PM EDT SATURDAY... NWS RADAR SHOWED ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WERE DEVELOP AT THE START OF THE 18Z TAF PERIOD WEST OF A LINE FROM BUENA VISTA VIRGINIA TO ROANOKE TO TAZEWELL VIRGINIA. KLWB HAS THE HIGHEST PROBABILITY OF HAVE THUNDERSTORMS BEFORE 00Z TODAY BUT MAY ALSO NEED TO ADD TSRA OR VCTS IN FOR THE KROA AND KBCB TAFS DEPENDING ON SHORT TERM RADAR TRENDS. ONCE THE SUN SET THE COVERAGE OF SHOWERS AND THUNDERSTORMS WILL DIMINISH. EXPECT PATCHY MVFR FOG OVERNIGHT. AIRPORT THAT GET RAIN THIS AFTERNOON ALSO HAVE A BETTER CHANCE OF HAVING FOG AFTER MIDNIGHT. SIMILAR TO SATURDAY MORNING FOG WILL BE SHALLOW AND WILL DISSIPATE BY 14Z/10AM SUNDAY. COLD FRONT WILL TRAIL ACROSS THE OHIO VALLEY ON SUNDAY. THIS WILL TURN SURFACE AND LOW LEVEL WINDS TO THE SOUTHEAST. NO OTHER UPPER SUPPORT FOR SHOWERS AND THUNDERSTORMS SUNDAY. ONCE AGAIN STORMS WILL DEVELOP BETWEEN 16Z-18Z/NOON-2PM BUT PROBABILITY IS NOT HIGH ENOUGH IN THAT TIME FRAME TO INCLUDE IN THE TAFS. EXTENDED DISCUSSION... THE SLOWLY APPROACHING FRONT WILL RESULT IN DEVELOPMENT OF MORE WIDESPREAD CONVECTION INITIALLY ALONG THE BLUE RIDGE SUNDAY AFTERNOON AND ACROSS MUCH OF THE WEST LATE IN THE DAY AS THE FRONT APPROACHES. SOME OF THE CONVECTION MAY SPREAD EAST OF THE BLUE RIDGE LATER IN THE AFTERNOON SO POTENTIAL FOR A LITTLE MORE IN THE WAY OF PERIODIC SUB-VFR SUNDAY AFTERNOON/EVENING ESPCLY OVER THE MOUNTAIN LOCATIONS. THIS BOUNDARY SHOULD FINALLY SINK SOUTH INTO THE REGION BY MONDAY RESULTING IN WIDESPREAD CONVECTION ESPCLY BLUE RIDGE EAST...WITH ADDITIONAL ROUNDS OF SHRA/TSRA INTO AT LEAST MONDAY NIGHT BEFORE THE BOUNDARY SINKS TO THE SOUTH. THIS SHOULD MAKE FOR MORE FREQUENT PERIODS OF SUB-VFR FROM SUNDAY NIGHT INTO TUESDAY WITH LOWER CIGS/VSBY REDUCTIONS DUE TO SHOWERS/STORMS DURING THE DAY...AND IN FOG OVERNIGHT INTO THE EARLY MORNING HOURS EACH DAY. LOWER MVFR/IFR CIGS ARE LIKELY BEHIND THE FRONT INTO THURSDAY WITH EASTERLY FLOW AND WEDGING IN PLACE RESULTING IN MVFR CEILINGS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS/JH NEAR TERM...JH SHORT TERM...PH LONG TERM...DS AVIATION...AMS/JH/WERT

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