Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 310805 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 405 AM EDT SUN AUG 31 2014 .SYNOPSIS...
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THE REGION WILL STAY BETWEEN A LARGE HIGH PRESSURE SYSTEM OVER THE SOUTHEAST UNITED STATES AND WESTERN ATLANTIC AND A COMPLEX LOW PRESSURE SYSTEM CROSSING THE GREAT LAKES. A COLD FRONT FINALLY ARRIVES FROM THE NORTH BY THURSDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 400 AM EDT SUNDAY... ELONGATED BAROCLINIC ZONE IS SUPPORTED BY AN UPPER JET AND AXIS OF VORTICITY THAT EXTENDS FROM THE LOWER MISSISSIPPI VALLEY TO NEW ENGLAND. UPPER RIDGE REMAINS PARKED OVER THE NORTH CAROLINA COAST. BAND OF DEEPER MOISTURE SHOWN ON WATER VAPOR AND TOTAL PRECIPITABLE WATER IMAGES WILL MAKE ONLY SLOW PROGRESS EAST INTO THE COUNTY WARNING AREA BY MONDAY MORNING. MODELS BRING CLUSTER OF SHOWERS AND THUNDERSTORMS OVER KENTUCKY AND TENNESSEE ACROSS MUCH OF THE FORECAST AREA THIS MORNING. NOT SURE HOW FAR EAST THIS PRECIPITATION WILL GET. 06Z HRRR HAD REASONABLE TIMING MOVING THE EASTERN EDGE INTO THE FORECAST AREA THROUGH 8AM SO WILL BE FOLLOWING THAT ALONG WITH RADAR TRENDS. LARGER BAND OF SHOWERS WILL PIVOT ENOUGH TO REACH SOUTHEAST WEST VIRGINIA TONIGHT...SIMILAR TO ORIENTATION OF WPC QPF FORECAST AND THE 00Z GFS...SLIGHTLY FARTHER SOUTH THAN THE 00Z NAM. 4KM NAM AND HRRR DEVELOP THUNDERSTORMS ALONG THE BLUE RIDGE THIS AFTERNOON...CLOSE TO THE EDGE OF THE THICKER CLOUD COVER. EXPECT THE COVERAGE OF THUNDERSTORMS IN THE EAST TO DIMINISH AFTER SUNSET. CLOUDS WILL LIMIT HEATING AND INSTABILITY TODAY. STAYED CLOSER TO BIAS CORRECTED MAV GUIDANCE FOR MAXIMUM TEMPERATURES. HUMID AIR MASS AND VERY MILD DEW POINTS WILL RESULT IN LITTLE COOLING TONIGHT. USED WARMER MET GUIDANCE FOR OVERNIGHT LOWS.
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&& .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
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AS OF 300 AM EDT SUNDAY... PROGRESSIVE NORTHERN STREAM FLOW WILL PRODUCE TROUGHING ACROSS THE NORTHEAST BY MONDAY MORNING. SEVERAL SHORTWAVES TRAVERSE ACROSS THE MID ATLANTIC REGION. THESE UPPER DISTURBANCES WILL SHAPE THE TIMING OF CONVECTION. AN UPPER DISTURBANCE WILL SHIFT ACROSS THE GREAT LAKES FROM THE OHIO RIVER VALLEY MONDAY MORNING...ENHANCING THE CHANCES OF SHOWERS IN THE WEST-NORTHWEST. THE SUBTROPICAL BERMUDA HIGH PRESSURE WILL REMAIN IN PLACE. A VERY MOIST SOUTHWEST FLOW WILL CONTINUE LABOR DAY. HIGH TEMPERATURES MONDAY WILL RANGE FROM THE UPPER 70S IN THE MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT. SCATTERED SHOWERS AND THUNDERSTORMS REDEVELOP MONDAY AFTERNOON WITH SOLAR HEATING. SOME OF THE THUNDERSTORMS MAY CONTAIN LOCALLY HEAVY RAINS. RAINFALL WILL DIMINISH QUICKLY AS THE SUN SETS AND SHOULD SEE DRY...ALBEIT WARM AND MUGGY...CONDITIONS PERSIST THROUGH MONDAY NIGHT. LOW TEMPERATURES MONDAY NIGHT WILL VARY FROM THE LOWER 60S IN THE WEST TO THE AROUND 70 IN THE EAST. DEEP LAYER MOISTURE INCREASES TUESDAY AS ANOTHER LOW PRESSURE SYSTEM MOVING ACROSS EASTERN CANADA WILL DRAG A COLD FRONT SOUTH OF THE GREAT LAKES. BETTER CHANCES FOR CONVECTION WILL BE FOUND ACROSS THE HIGHER TERRAIN...WHERE STRONGER UPPER LEVEL SUPPORT WILL BE LOCATED. HIGHS TUESDAY WILL CLIMB INTO THE LOWER 80S IN THE MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT. MODEL TREND HAVE BEEN SLOWING THE TIMING OF THE FRONT AND EXPECT THE COLD FRONT WILL STALL FURTHER NORTH TUESDAY NIGHT DUE TO THE UPPER LEVEL RIDGING IN PLACE ACROSS THE SOUTHEAST STATES. LOWS WILL FALL INTO THE MID 60S TO THE LOW 70S TUESDAY NIGHT. KEPT THE HIGHEST POPS ACROSS THE SOUTH WEDNESDAY ALONG THE STALLED FRONTAL BOUNDARY. WHILE...HIGH PRESSURE PASSING ACROSS THE GREAT LAKES SHOULD KEEP THE NORTHERN HALF OF OUR AREA DRY. HIGHS WEDNESDAY WILL BE FROM THE LOWER 80S IN THE WEST TO AROUND 90 DEGREES IN THE EAST. SLOWLY DRY THINGS OUT WEDNESDAY NIGHT FROM NORTH TO SOUTH. LOW TEMPERATURES WILL DROP INTO THE UPPER 50S IN THE NORTHWEST MOUNTAINS TO NEAR 70 DEGREES IN THE PIEDMONT.
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&& .LONG TERM /THURSDAY THROUGH SATURDAY/...
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AS OF 330 PM SATURDAY... UPPER LEVEL RIDGING WILL SHIFT NORTHWARD FROM THE SOUTHEAST STATES OVER THE MID ATLANTIC DURING THE SECOND HALF OF THE WEEK...RESULTING IN BOTH WARMER TEMPERATURES AND WEAKER WINDS ALOFT. THIS WILL MAKE FOR MORE STABLE CONDITIONS THAT WILL KEEP SHOWER AND THUNDERSTORM ACTIVITY DISORGANIZED THROUGH THE PERIOD. ANY RAINFALL WHICH DEVELOPS WILL BE DRIVEN MAINLY BY DAYTIME HEATING...WHICH WILL ALLOW THIS ACTIVITY TO FIZZLE AFTER SUNSET. HIGH PRESSURE WILL PASS OFF THE NEW ENGLAND COAST ON THURSDAY... RESULTING IN A WEAK WEDGING PATTERN WITH EASTERLY FLOW OFF THE ATLANTIC. THIS WILL LIKELY BE THE DRIEST DAY OF THE PERIOD. WINDS WILL SHIFT SOUTHWESTERLY AGAIN ON FRIDAY AS ANOTHER COLD FRONT SINKS SOUTH FROM THE GREAT LAKES. STRONGER FLOW OFF THE ATLANTIC WILL RESULT IN INCREASED MOISTURE...AND WILL EXPECT SPOTTY SHOWER AND THUNDERSTORM ACTIVITY DURING THE AFTERNOON AND EVENING. EXPECT TEMPERATURES TO REMAIN SLIGHTLY ABOVE NORMAL FOR THE PERIOD.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/... AS OF 125 AM EDT SUNDAY... SATELLITE PICTURES SHOWED AN EXPANSIVE BAND OF DEEP MOISTURE FROM THE GULF OF MEXICO INTO THE GREAT LAKES. AXIS OF VORTICITY ALONG THIS SAME CORRIDOR WILL GENERATE SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT. ONGOING SHOWERS AND THUNDERSTORMS OVER THE TENNESSEE AND OHIO VALLEYS EARLY THIS MORNING WILL GRADUALLY MOVE EAST IN TO WEST VIRGINIA AND VIRGINIA TODAY. LOWER CONFIDENCE AS TO HOW FAR EAST THIS PRECIPITATION WILL GET BY 00Z/8PM. FOR NOW HAVE LEFT PRECIPITATION OUT OF THE KBCB AND KROA TAFS. ALSO KEPT KLYH AND KDAN DRY. HIGHER CONFIDENCE THAT KLWB AND KBLF WILL HAVE A PROLONGED PERIOD OF SHOWERS OVERNIGHT. MODELS BRING IFR CEILINGS INTO KLYH AND KDAN EARLY THIS MORNING. EXPECT ANY STRATUS THAT DOES DEVELOP WILL LIFT TO VFR SHORTLY AFTER SUNRISE. EXTENDED DISCUSSION... IMPULSES EXIT BY MONDAY LEAVING THE REGION IN BETWEEN THIS EXITING SYSTEM AND THE NEXT UPSTREAM COLD FRONT. THIS SHOULD ALLOW FOR MORE IN THE WAY OF WIDESPREAD VFR ON MONDAY AFTER EARLY FOG FADES WITH ONLY ISOLATED CONVECTION LIKELY DURING THE AFTERNOON INCLUDING SPOTTY MVFR. ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS AS IT APPROACHES FROM THE NW TUESDAY...THEN PERHAPS BETTER COVERAGE OF SHRA/TSRA WEDNESDAY WITH THE FRONT PASSING...AND ACROSS THE SOUTH THURSDAY WHERE THE BOUNDARY LOOKS TO STALL. HOWEVER TIMING AND SOUTHWARD EXTENT OF THE BOUNDARY QUITE LOW CONFIDENCE AT THIS POINT. THUS APPEARS MAINLY VFR FOR NOW TUE-THU OUTSIDE OF AFTERNOON/EVENING CONVECTION AND TYPICAL EARLY MORNING FOG IN THE VALLEYS AND WHERE EARLIER HEAVY RAIN OCCURRED. && .EQUIPMENT... AS OF 730 AM EDT FRIDAY ... THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...KK LONG TERM...NF AVIATION...AMS EQUIPMENT...AMS

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