Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 300610 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 210 AM EDT SUN AUG 30 2015 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE WILL LIFT NORTH ALONG THE APPALACHIANS SUNDAY INTO MONDAY...BRINGING A GREATER CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS TO THE REGION. UPPER LEVEL HIGH PRESSURE WILL THEN STRENGTHEN AND KEEP US IN A RATHER STAGNANT PATTERN...WITH A CHANCE FOR AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS THROUGH THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 730 PM EDT SATURDAY... SHOWERS ARE FEW AND FAR BETWEEN AND NOT REALLY SEEING ANY ON RADAR IN OUR CWA...THOUGH SOME LIGHT RETURNS ARE JUST SOUTH OF THE NC MTNS/FOOTHILLS. SEEMS THE THREAT WILL BE A BIT LIMITED SO CUT BACK POPS THIS EVENING..AND TRIED TO CAPTURE SOME OF THE HI-RES ARW AS IT KEPT THINGS DRY OVER MOST OF THE CWA. WILL BE DEALING WITH MID AND HIGH CLOUDS THROUGH THE NIGHT WITH POSSIBLE LOWER CLOUDS IN THE WEST AND MIDDLE PART OF THE CWA. THIS WILL BE OBSCURING FOR MOST FOLKS THE SUPERMOON THAT IS EXPECTED OVERNIGHT. PREVIOUS VALID DISCUSSION... GENERALLY EXPECTING LOW TO MID 60S ACROSS THE PIEDMONT TO UPPER 50S/LOWER 60S WEST OF THE BLUE RIDGE. THERE MAY ALSO BE SOME FOG DEVELOPMENT IN THE VALLEYS WEST OF THE BLUE RIDGE FOR AREAS THAT MANAGE TO SEE ANY SUBSTANTIAL BREAKS IN THE CLOUDS. THEN AFTER SEVERAL DAYS OF LITTLE CHANGE IN THE SYNOPTIC PATTERN...A CLOSED LOW THAT HAS BEEN SPINNING OVER THE NORTHERN GULF OF MEXICO WILL BE OPENING UP AND THROWING SHORT WAVE ENERGY IN OUR DIRECTION TOMORROW. WATER VAPOR IMAGERY ALSO SHOWS EXCELLENT MOISTURE TRANSPORT FROM THE GULF WHICH WILL BOOST OUR PRECIPITABLE WATER VALUES INTO THE 1.0 TO 1.5 INCH RANGE. THIS WILL BE ENOUGH TO GENERATE A MORE WIDESPREAD CHANCE FOR SHOWERS/SLIGHT CHANCE FOR THUNDER ON SUNDAY WITH A LOCAL DOWNPOUR POSSIBLE. THERE REMAINS LITTLE IN THE WAY OF INSTABILITY OR SHEAR SO DO NOT SEE ANY THREAT OF SEVERE WEATHER. HIGHS TOMORROW WILL RANGE FROM THE MID/UPPER 80S EAST TO UPPER 70S/LOWER 80S WEST. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... AS OF 355 PM EDT SATURDAY A PIECE OF THE UPPER TROF AND VORTICITY MAXIMUM TRACKS SLOWLY NORTH ACROSS THE SOUTHERN AND CENTRAL APPALACHIANS SUNDAY NIGHT. AT THE SAME TIME A WEAK SHORT WAVE TRACKING THE THE BASE OF AN UPPER TROF OVER NEW ENGLAND WILL CROSS THROUGH THE OHIO VALLEY. BY MONDAY EVENING THE MODELS HAVE THE UPPER TROF AXIS EAST OF THE FORECAST AREA. THE COMBINATIONS OF THE LIFT FROM THESE FEATURES WILL RESULT IN SHOWERS AND THUNDERSTORMS SUNDAY NIGHT AND MONDAY. MOISTURE BELOW 850 MB IS NOT AS HIGH AS WOULD BE OPTIMAL AND SURFACE/LOW LEVEL WINDS WILL NOT CONTRIBUTE TO LIFT OR MOISTURE ADVECTION. WILL HAVE A SMALL INCREASE IN PROBABILITY OF PRECIPITATION ON SUNDAY NIGHT AND MONDAY. 500 MB TEMPERATURES WILL COOL LATE SUNDAY NIGHT AND MONDAY MORNING BUT LIFTED INDEX VALUES AND HEATING WILL BE MEAGER ON MONDAY. CAPES AROUND 500 J/KG BUT ARE AT A RELATIVE MINIMUM OVER THE FORECAST AREA WITH HIGHER VALUES SURROUNDING US. KEPT PROBABILITY OF THUNDER AT SLIGHT CHANCE. PRECIPITABLE WATER VALUES AND DEW POINTS WILL BE SLOWLY INCREASING SUNDAY NIGHT AND MONDAY. THIS PLUS THE CLOUD COVER WILL LIMIT DROP IN MINIMUM TEMPERATURES ON SUNDAY NIGHT. CLOUDS AND ANY PRECIPITATION WILL HOLD DOWN RISE IN MAXIMUM TEMPERATURES ON MONDAY. LITTLE CHANGE NEEDED TO FORECAST FOR MONDAY NIGHT AND TUESDAY. PROBABILITY OF PRECIPITATION DECREASES AND TEMPERATURES WILL BE NEAR NORMAL. A MAJORITY ON THE DEEP MOISTURE WILL STAY JUST SOUTH AND SOUTHEAST OF THE FORECAST AREA. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 255 PM EDT SATURDAY... LONG WAVE SYNOPTIC PATTERN THROUGH THE PERIOD KEEPS UPPER TROFING OVER THE PACIFIC NORTHWEST AND AN LARGE RIDGE OVER THE CENTRAL UNITED STATES. AT THE SURFACE A BROAD AREA OF HIGH PRESSURE WILL REMAIN OVER THE EASTERN UNITED STATES. MODELS NOT SHOWING ANY WELL DEFINED OR ORGANIZED SMALLER SCALE FEATURES THAT WILL TRIGGER SHOWERS AND THUNDERSTORMS THROUGH DAY 7. BULK OF SHOWERS AND THUNDERSTORMS WILL BE TYPICAL AFTERNOON AND EVENING OROGRAPHICALLY DRIVEN COVERAGE. STEERING FLOW WILL REMAIN RELATIVELY WEAK SO ANY STRONGER CELLS WILL HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN. NO EXCEPTIONALLY WARM OR COOL TEMPERATURES THROUGH DAY 7. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 200 AM EDT SUNDAY... FOR THE OVERNIGHT...MAINLY MID/HIGH CLOUDS WILL CONTINUE MOVING IN FROM THE SOUTH. LOW LEVELS REMAIN DRY ENOUGH HOWEVER FOR SUFFICIENT RADIATIONAL COOLING TO ALLOW FOR SOME LIGHT FOG/MIST ACROSS THE AREA...DROPPING VISIBILITIES TO 4SM IN SPOTS. MAY ALSO SEE RIVER VALLEY FOG DEVELOP ACROSS THE MOUNTAINS...WHICH MAY LOWER VISIBILITIES IN THE IMMEDIATE AREA TO LESS THAN 1SM. ANY FOG DEVELOPING OVERNIGHT WILL DISSIPATE QUICKLY AFTER 30/14Z SUNDAY WITH INCREASED DAYTIME HEATING...RESULTING IN VFR CONDITIONS THROUGH THE DAY. WITH AN UPPER LEVEL DISTURBANCE APPROACHING...SHOWER COVERAGE WILL BE INCREASED SUNDAY AFTERNOON... BUT STILL EXPECT ONLY A SCATTERED THREAT. AS SUCH...BELIEVE ANY REDUCTIONS IN VISIBILITIES WILL BE LIMITED TO THOSE IN RAINFALL... WHICH SHOULD BE BRIEF. WITH SHORT WAVE ENERGY LIFTING NORTHWARD FROM THE GULF COAST REGION...WILL SEE MORE WIDESPREAD CONVECTION SUNDAY NIGHT INTO MONDAY MORNING. EXTENDED AVIATION DISCUSSION... GENERALLY EXPECT THE BEST CHANCES FOR MVFR/IFR TO BE LATE NIGHT/EARLY MORNING DUE TO FOG AND STRATUS DEVELOPMENT FROM THE BLUE RIDGE WEST ESPECIALLY AT KLWB/KBCB. WILL THEN REMAIN IN A WEAKLY FORCED SYNOPTIC ENVIRONMENT THROUGH MIDWEEK WITH CHANCES FOR DIURNAL CONVECTION MAINLY FROM THE BLUE RIDGE WEST...AND SOME MVFR/IFR FOG/STRATUS DEVELOPMENT AT NIGHT ESPECIALLY AT KBCB AND KLWB. && .EQUIPMENT... AS OF 400 PM EDT SATURDAY... THE DEW POINT READING AT KJFZ...RICHLANDS VA AWOS...IS INCORRECT. AT THIS TIME WE DO NOT KNOW WHEN THIS SENSOR WILL BE REPAIRED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...MBS/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...NF/WP EQUIPMENT...

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