Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 290804 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 404 AM EDT FRI AUG 29 2014 .SYNOPSIS... A WEAK FRONT WILL BE STATIONARY FROM NORTH CAROLINA TO MISSOURI TODAY. THIS FRONT WILL LIFT NORTH INTO THE OHIO VALLEY TONIGHT. A STRONGER SYSTEM WILL BRING A BETTER THREAT FOR SHOWERS AND STORMS FOR SUNDAY AND MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 400 AM EDT FRIDAY... STATIONARY FRONT TRAILED FROM NORTHEAST NORTH CAROLINA TO NORTH CENTRAL TENNESSEE EARLY THIS MORNING. ALONG THE BOUNDARY AND WEST OF THE BLUE RIDGE MODELS WERE SHOWING A CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING. WILL BE STARTING OFF THE DAY CAPPED. EVEN IF THE CAP DOES BREAK...AS SUGGESTED BY BUFKIT NAM/RAP GUIDANCE...NOT MUCH INSTABILITY...AND NOT UNTIL AFTER 18Z. WITH THE SHORT WAVE ENERGY WELL WEST AND NORTH OF THE FORECAST AREA...LITTLE TO AIDE IN THE FORCING TODAY. AXIS OF POOLED MOISTURE AND LOW LEVEL CONVERGENCE ALONG THE WEAK BOUNDARY PIVOTS NORTHEAST TONIGHT AND WILL EXTEND FROM OHIO INTO EASTERN NORTH CAROLINA BY SATURDAY MORNING. WILL HAVE BEST PROBABILITY OF SHOWERS AND THUNDERSTORMS IN THE EXTREME SOUTHWEST COUNTY WARNING AREA. AREAL COVERAGE OF PRECIPITATION SHOULD ONLY BE ISOLATED TO SCATTERED. STORM MOTION WOULD BRING THE STORMS INTO SOUTHEAST WEST VIRGINIA AND POSSIBLY THE NEW RIVER VALLEY AROUND 00Z. BUT NOT MUCH INSTABILITY LEFT BY THAT TIME. SOUTHEAST WINDS AT THE SURFACE THROUGH LOW LEVELS...BRING 850-1000MB RELATIVE HUMIDITY UP TODAY AND BY TONIGHT LOW CLOUDS ARE EXPECTED TO ADVANCE TOWARD THE EAST SIDE OF THE APPALACHIANS. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 310 AM EDT FRIDAY... UPPER RIDGE EXPECTED TO SHIFT EAST AS STRONGER UPPER TROUGH MOVES FROM THE UPPER MIDWEST INTO THE GREAT LAKES. MODELS AGREE THAT A SOUTHERN STREAM UPPER SHORTWAVE WITH ENHANCEMENT IN THE JET WILL STREAK OVER THE GULF COAST STATES AND ACROSS THE WESTERN SLOPES OF THE APPALACHIANS SUNDAY. FOR SATURDAY THOUGH...MAINLY LOOKING WEAK FLOW ALOFT WITH SOME CONVERGENCE ACROSS THE MTNS PER SOUTH-SOUTHEAST FLOW. MODELS ARE FAVORING A BIT OF CONVECTION WITH THE LEE TROUGH IN THE EAST...MAINLY FROM THE EASTERN WV PANHANDLE SOUTHEAST TOWARD THE TIDEWATER. THINK THE AIRMASS WILL BE UNSTABLE AND MOIST ENOUGH TO TRIGGER A FEW STORMS BUT OVERALL UPPER SUPPORT IS LACKING SO ONLY SEEING ISOLATED COVERAGE OVER THE MTNS AND NORTH OF A ROANOKE TO DANVILLE LINE. MORE SUN SATURDAY WILL BRING TEMPS TOWARD 90 OUT EAST WITH MID 80S WEST. SAT NIGHT...MAIN AXIS OF CONVECTION WILL RUN FROM MS-KY...WITH LITTLE TO NO CHANCE OF SHOWERS EAST OF THE BLUE RIDGE AFTER EVENING STORMS WANE. WITH THE UPPER SUPPORT TRACKING CLOSER WILL HAVE AT LEAST SLIGHT CHANCE INTO THE MOUNTAINS LATE. SUNDAY LOOKS ACTIVE AS THE SHORTWAVE AXIS SHIFTS ACROSS KY INTO NORTHERN WV...WITH STRONG CONVERGENCE AND LIFT. WILL SEE HIGH CHANCE/LIKELY POPS. LOOKS LIKE CLOUD COVER COULD ARRIVE SOON ENOUGH TO KEEP INSTABILITY LOWER...BUT ENOUGH UPPER SUPPORT/SHEAR WHERE A FEW STORMS COULD PRODUCE GUSTY WINDS. THE SHORT WAVE AXIS SLOWLY SHIFTS TO THE EAST AND WITH A LEE TROUGH...CONVECTION FIRES LATE IN THE AFTERNOON AND MAY REMAIN OVER SOUTHSIDE UNTIL MIDNIGHT. HIGHS SUNDAY WILL RANGE FROM THE UPPER 70S MOUNTAINS TO UPPER 80S TOWARDS SOUTHSIDE. OVERALL...LABOR DAY WEEKEND LOOKING VERY WARM/HOT/HUMID. SATURDAY NOT TOO BAD RAIN WISE...BUT STAY COOL WHILE DRINKING PLENTY OF WATER IF OUTDOORS. SUNDAY APPEARS POOR FOR OUTDOOR ACTIVITIES. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 300 PM EDT THURSDAY... MUCH OF THE LONG TERM PERIOD WILL BE INFLUENCED BY A MEAN UPPER RIDGE THAT WILL INITIALLY RESIDE ALONG AND OFF THE SOUTHEAST COAST...WHICH GRADUALLY RETROGRESSES AND EXPANDS WESTWARD INTO THE GULF COAST STATES BY THE END OF THE FORECAST PERIOD. SOUTHEASTERN RIDGE WILL INITIALLY BE STRONG ENOUGH TO DEFLECT ANY NORTHERN STREAM ENERGY AWAY FROM THE BLACKSBURG FORECAST AREA...WITH MAIN BAROCLINIC ZONE REMAINING FROM THE NORTHERN PLAINS EAST INTO AND THROUGH THE GREAT LAKES INTO NEW ENGLAND. HOWEVER...TAP OF TROPICAL MOISTURE RIDING AROUND PERIPHERY OF SOUTHEASTERN RIDGE LIKELY TO REMAIN OVER/NEAR THE BLACKSBURG FORECAST AREA THROUGH AT LEAST MONDAY OR MONDAY NIGHT...MAINTAINING THREAT FOR MAINLY DIURNALLY DRIVEN SCATTERED SHOWERS AND THUNDERSTORMS...SOME OF WHICH MAY BE ACCOMPANIED BY LOCALLY HEAVY RAIN CONSIDERING RELATIVELY HIGH PRECIPITABLE WATER VALUES EXPECTED OVER THE AREA. GRADUAL RETROGRESSION OF UPPER RIDGE INTO NORTHERN GULF COAST REGION DURING THE MIDWEEK PERIOD SHOULD BE SUFFICIENT TO ALLOW WINDS ALOFT TO VEER SUCH THAT INFLUENCE OF TROPICAL MOISTURE TAP GRADUALLY WANES...ONLY TO BE REPLACED BY MORE AGGRESSIVE SOUTHWARD INTRUSION OF NORTHERN STREAM ENERGY AND ASSOCIATED SCATTERED SHOWERS/STORMS IN ADVANCE OF AN ACCOMPANYING DECAYING COOL FRONT INTO THE MID APPALACHIAN AND MID ATLANTIC REGION IN TUESDAY-WEDNESDAY TIMEFRAME. PUSH OF POST-FRONTAL SLIGHTLY DRIER AIR MAY BE STRONG ENOUGH TO REDUCE THREAT FOR PRECIPITATION ACROSS AREAS NORTH OF INTERSTATE 64 BY THURSDAY...BUT WITH AT LEAST A CHANCE THREAT FOR SHOWERS/STORMS REDEVELOPING BY AFTERNOON ACROSS THE SOUTHWESTERN MOUNTAINS CLOSER TO DECAYING FRONTAL BOUNDARY AND PROXIMITY TO HIGHER THETA-E AIR. PLENTY OF CLOUD COVER AND DEWPOINTS PRIMARILY IN THE 60S SHOULD ENSURE THAT TEMPERATURES REMAIN CLOSE TO SEASONAL AVERAGES...MAINLY MID 70S TO LOWER 80S ACROSS THE HIGHER ELEVATIONS BY DAY WITH UPPER 80S ACROSS THE PIEDMONT...WITH MAINLY 60S AT NIGHT. INTRUSION OF SLIGHTLY COOLER/DRIER POST-FRONTAL AIR FROM THE NORTHEAST MAY ALLOW TEMPERATURES TO BE A FEW DEGREES COOLER ON THURSDAY. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... AS OF 135 AM EDT FRIDAY... A STATIONARY FRONT EXTENDED FROM AROUND NORFOLK TO JUST SOUTH OF KDAN TO NORTHEAST TENNESSEE. EAST WINDS NORTH OF THE BOUNDARY WERE EXPECTED TO BRING A STRATUS LAYER IN FROM THE COAST. LOW CONFIDENCE AT THIS TIME THAT KLYH OR KDAN WILL DROP TO MVFR CEILINGS OR LOWER BEFORE 12Z/8AM. THE SKY WAS CLEAR AT KLWB AND WITH A SMALL TEMPERATURE/DEW POINT DEPRESSION...EXPECTING FOG WILL DEVELOP EARLY THIS MORNING. MEDIUM CONFIDENCE OF AT LEAST IFR VISIBILITY AT THIS AIRPORT AFTER 09Z/5AM. THERE WILL BE LITTLE CHANGE IN THE WEATHER PATTERN TODAY AND TONIGHT. THE BEST PROBABILITY OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING WILL REMAIN SOUTH OF THE FORECAST AREA. NO MENTION OF SHOWERS OR THUNDERSTORMS NEEDED IN THE TAFS AT THIS TIME. EXTENDED DISCUSSION... WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL AFFECT THE REGION AGAIN ON SATURDAY...MAINLY DURING THE LATE AFTERNOON AND EARLY EVENING. SHOULD ONE OF THESE STORMS DEVELOP NEAR A TAF LOCATION IT COULD RESULT IN A BRIEF PERIOD OF SUB VFR CONDITIONS. AN AREA OF LOW PRESSURE IS FORECAST TO MOVE THROUGH THE GREAT LAKES SATURDAY NIGHT AND SUNDAY...THE ASSOCIATED COLD FRONT TRAILING SOUTH AND MOVING ACROSS THE OHIO/TN VALLEYS. SHOWERS AND THUNDERSTORMS WILL LIKELY BE ASSOCIATED WITH THIS FRONT...THIS ACTIVITY SPREADING EAST INTO THE CENTRAL APPALACHIANS SUNDAY AND MONDAY. SHOWER COVERAGE SUNDAY/MONDAY IS EXPECTED TO BE MORE WIDESPREAD AS COMPARED TO FRIDAY AND SATURDAY. && .EQUIPMENT... AS OF 400 AM EDT FRIDAY ... THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...REMAINS OUT OF SERVICE. A PART HAS BEEN ORDERED. REPAIRS WILL BE DONE TODAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...RCS LONG TERM...WERT AVIATION...AMS/CF EQUIPMENT...AMS

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