Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 291744 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 144 PM EDT TUE JUL 29 2014 .SYNOPSIS... UPPER LEVEL LOW PRESSURE WILL REMAIN CENTERED OVER EASTERN CANADA THROUGH THE MIDDLE OF THE WEEK...WHILE COOL HIGH PRESSURE SETTLES OVER THE REGION THROUGH WEDNESDAY. THESE COOL AIRMASSES WILL KEEP TEMPERATURES BELOW NORMAL OVER THE NEXT FEW DAYS. DURING THE LATTER HALF OF THE WEEK AND HEADING INTO THE WEEKEND...THE UPPER TROUGH WILL RETROGRADE WESTWARD...ALLOWING FOR AN INCREASE IN MOISTURE...MODERATING TEMPERATURES...AND POTENTIAL FOR SHOWERS AND STORMS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1255 PM EDT TUESDAY... FOR THE EARLY AFTERNOON UPDATE...THE BIGGEST ADJUSTMENT HAS BEEN TO THE EXPECTED REGION OF THE AREA THAT MAY EXPERIENCE SOME ISOLATED SHOWERS THIS AFTERNOON. LATEST REGIONAL RADAR TRENDS DEPICT THE GREATEST CONCENTRATION ALONG A NARROW LINE EXTENDING FROM WESTERN GREENBRIER COUNTY WV...NORTHWEST INTO CENTRAL WV. GIVEN THAT THE SHOWER ACTIVITY WAS PROGRESSING SOUTHEAST...PARTS OF GREENBRIER COUNTY SHOULD CONTINUE TO BE THE FOCUS FOR THE GREATEST CONCENTRATION HEADING THROUGH THE AFTERNOON. ELSEWHERE...COVERAGE WAS VERY LIMITED OR NON-EXISTENT. HRRR AND LOCAL RNK WRK-ARW MODELS ARE OFFERING SOLUTIONS THAT GENERATE ISOLATED SHOWERS NEAR AND JUST EAST OF THE CREST OF THE BLUE RIDGE THIS AFTERNOON...MAINLY NEAR AND SOUTHWEST OF ROANOKE INTO THE MOUNTAINS OF NORTH CAROLINA. OTHER ISOLATED COVERAGE IS PROGGED OVER PARTS OF THE MOUNTAIN EMPIRE REGION OF SOUTHWEST VIRGINIA. OUR ONGOING FORECAST ALREADY REFLECT ISOLATED COVERAGE IN MOST OF THESE AREAS. HAVE ADDED A SMALL REGION OF ISOLATED SHOWERS THIS AFTERNOON BETWEEN ROUGHLY FLOYD AND MARTINSVILLE VA. REPORTED TEMPERATURES HAVE BEEN TRENDING JUST A LITTLE HIGHER THAN THE EARLIER FORECAST ACROSS PARTS OF THE REGION. HAVE INCREASED FORECAST HIGH TEMPERATURES ACCORDINGLY. MOST ADJUSTMENTS WERE ACROSS THE SOUTHERN AND WESTERN PARTS OF THE REGION. NO OTHER SIGNIFICANT CHANGES AT THIS TIME. AS OF 950 AM EDT TUESDAY... CURRENT PROJECTION OF ARRIVAL OF ISOLATED SHOWERS IN THE WEST LATER THIS MORNING LOOKS ON TRACK BASED UPON THE LATEST REGIONAL RADAR TRENDS. HAVE MAKE MINOR TWEAKS TO THE TEMPERATURE AND DEW POINT GRIDS BASED UPON THE LATEST OBSERVATIONS...AND EXPECTED TRENDS INTO THE EARLY AFTERNOON. MADE MINOR ADJUSTMENTS TO THE SKY COVER TO REFLECT A GREATER ABUNDANCE CURRENTLY OVER SOUTHSIDE VIRGINIA AND NEIGHBORING SECTIONS OF NORTH CENTRAL NORTH CAROLINA. OTHER THAN THIS MINOR ADJUSTMENTS...NO OTHER NOTABLE CHANGES FOR THIS UPDATE. AS OF 400 AM EDT TUESDAY... FOR THE REMAINDER OF THE MORNING...WILL SEE A FEW SHOWERS DEVELOP ALONG THE WESTERN RIDGES FROM TIME TO TIME...PERHAPS PASSING AS FAR EAST AS THE NEW RIVER VALLEY BEFORE DISSIPATING IN THE NORTHWESTERLY DOWNSLOPE FLOW. A FEW HUNDREDTHS OF AN INCH RAINFALL IS LIKELY ACROSS PORTIONS OF OUR WEST VIRGINIA/MOUNTAIN EMPIRE COUNTIES...WITH AMOUNTS TAPERING DOWN TO A TRACE FURTHER EAST. WINDS ACROSS THE AREA APPEAR TO BE HOLDING JUST STRONG ENOUGH MOST PLACES TO KEEP THE ATMOSPHERE MIXED...WHICH SHOULD LIMIT FOG FORMATION TO ISOLATED POCKETS IN THE DEEPER MOUNTAIN VALLEYS. THE MAIN STORY FOR TUESDAY WILL BE ANOTHER DAY OF COOL...EARLY AUTUMN-LIKE WEATHER AS A DEEP UPPER LEVEL LOW CONTINUES TO DRIFT SLOWLY NEAR HUDSON BAY CANADA. LOW CLOUDS ACROSS THE MOUNTAINS WILL LIFT AND SCATTER BY LATE MORNING...RESULTING IN A MIX OF CLOUDS AND SUNSHINE THROUGH THE AFTERNOON. WILL ALSO SEE MORE SPOTTY SHOWER ACTIVITY DEVELOP ACROSS THE MOUNTAINS AS SUBTLE DISTURBANCES PASS OVERHEAD. WITH HIGH PRESSURE BEGINNING TO SETTLE INTO THE AREA FROM THE CENTRAL MISSISSIPPI VALLEY...WE CAN ALSO EXPECT CALMER WIND SPEEDS THROUGH THE DAY WHICH WILL CUT DOWN ON THE CHILL THAT THE STRONGER GUSTS PRODUCE. STILL...IF OUTDOORS FOR EXTENDED PERIODS OF TIME TODAY ACROSS THE MOUNTAINS...YOU MAY CONSIDER KEEPING A LIGHT JACKET HANDY AS AFTERNOON HIGHS RANGE FROM THE MID 60S TO THE LOW 70S. HIGHS EAST OF THE BLUE RIDGE WILL BE WARMER...CLIMBING INTO THE MID/UPPER 70S...PERHAPS TOUCHING 80 OVER THE SOUTHSIDE. MOSTLY CLEAR SKIES AND LIGHT WINDS WILL ALLOW FOR STRONG RADIATIONAL COOLING TUESDAY NIGHT...ALLOWING OVERNIGHT TEMPERATURES TO FALL INTO THE 50S MOST LOCATIONS...AND IN THE LOW TO MID 40S IN A FEW OF THE DEEPER MOUNTAIN VALLEYS. AT THIS TIME...THINK MOST LOCATIONS WILL STAY A COUPLE DEGREES ABOVE RECORD LOWS...ALTHOUGH IT WILL BE CLOSE FOR DANVILLE. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... AS OF 230 AM EDT TUESDAY... MODELS CONTINUE TO BE IN GOOD AGREEMENT THAT THE FULL-LATITUDE UPPER TROF ACROSS THE EASTERN HALF OF THE UNITED STATES RELAXES SOME ON WEDNESDAY AS AN UPPER LEVEL IMPULSE MOVES SOUTH INTO THE NORTHERN PLAINS. THIS...COMBINED WITH THE UPPER RIDGE IN THE ATLANTIC NOSING EAST...WILL SHIFT THE UPPER TROF AXIS TO THE WEST ON THURSDAY...PLACING OUR AREA IN AN UPPER LEVEL SOUTHWEST FLOW ON THE EAST SIDE OF THE TROF. MODELS ARE TRENDING WETTER IN THE MOUNTAINS ON WEDNESDAY AFTERNOON AS WEAK UPSLOPE FLOW AND STEEP LAPSE RATES RING OUT SHALLOW MOISTURE. WITHOUT UPPER LEVEL SUPPORT...COVERAGE SHOULD BE VERY LIMITED AND INSERTED ONLY A SMALL CHANCE FOR PRECIPITATION IN THE WESTERN GREENBRIER VALLEY. TEMPERATURES BEGIN TO MODIFY ON WEDNESDAY AS 1000-850MB THICKNESSES INCREASE. GUIDANCE HAS SHOWN GOOD RUN TO RUN CONSISTENCY WITH FORECAST HIGHS FROM THE 70S IN THE MOUNTAINS TO 80-85 EAST OF THE BLUE RIDGE. CENTER OF A SFC HIGH IS FORECAST TO RESIDE OVER SOUTHERN WV/WESTERN VA BY 12Z (8 AM THURSDAY)...LEADING TO ANOTHER COOL NIGHT. HOWEVER...RH CROSS SECTIONS INDICATE HIGH LEVEL CLOUDS BEGIN TO STREAM OVER THE REGION FROM THE SOUTH...WHICH COULD SLOW FALL IN TEMPS. INCREASED LOWS A DEGREE...WHICH KEEPS ALL CLIMATE SITES AT LEAST A FEW DEGREES ABOVE RECORDS FOR THURSDAY MORNING. MOISTURE AND WARMER 850MB TEMPS...ALONG WITH AN INCREASE IN CLOUD COVER SURGES NORTH OVER OUR AREA THURSDAY. INCREASED HIGHS A DEGREE OR TWO...BUT ABUNDANT MID/HIGH CLOUDS WILL LIMIT WARMING. WEAK SOUTHEAST UPSLOPE FLOW AND DEVELOPING ISENTROPIC LIFT MAY GENERATE SOME SHOWERS ALONG THE BLUE RIDGE. INCREASED COVERAGE FOR SHOWERS THURSDAY AND THURSDAY NIGHT ALONG THE BLUE RIDGE. LOWS FRIDAY MORNING WILL ALSO PUSHED UP WITH ANTICIPATED WIDESPREAD CLOUDINESS. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 345 PM EDT MONDAY... UPPER 500 MB TROF OVER THE NORTHEAST UNITED STATES AMPLIFIES ON FRIDAY AND SATURDAY WITH A SIGNIFICANT SHORT WAVE OVER THE OHIO VALLEY. MODELS SIMILAR IN SHOWING HEIGHT FALLS ON THE SOUTHERN END OF THE TROF AND WHAT MAY EVENTUALLY BE A CUT OFF LOW OVER THE LOWER MISSISSIPPI VALLEY OR SOUTHEAST UNITED STATES MONDAY. MOISTURE BEGINS TO INCREASE ACROSS THE AREA ON FRIDAY BUT LITTLE IN THE WAY OF ANY ORGANIZED LIFT TO TRIGGER ANY PRECIPITATION ASIDE FROM DAILY THREAT OF AIRMASS TYPE SHOWERS AND THUNDERSTORMS. WITH LITTLE CHANGE IN THE AIR MASS THERE WILL BE MINIMAL CHANGES IN HIGH AND LOW TEMPERATURES EACH DAY. TEMPERATURES WILL BE NEAR NORMAL. NOT ANTICIPATING ANY EXTREMES. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 130 PM EDT TUESDAY... VFR CONDITIONS PREVAIL ACROSS THE AREA WITH A MIX OF PARTLY TO MOSTLY CLOUDY CUMULUS CLOUDS ACROSS THE REGION. THERE HAS BEEN LESS SHOWER ACTIVITY AS COMPARED TO THIS TIME YESTERDAY. MOST OF THE ACTIVITY HAS BEEN NEAR OR WEST OF KLWB WITH DONE ELSEWHERE. CANNOT RULE OUT ISOLATED DEVELOPMENT THE REMAINDER OF THE AFTERNOON NEAR THE CREST OF THE BLUE RIDGE AND OVER PARTS OF THE MOUNTAIN EMPIRE OF SOUTHWEST VIRGINIA AND THE NORTHERN MOUNTAINS OF NORTH CAROLINA. OVERNIGHT...THE CENTER OF SURFACE HIGH PRESSURE MOVES OVERHEAD. EXPECT VERY LIGHT IF NOT CALM WINDS...AND CUMULUS CLOUDS DISSIPATING AT OR AROUND SUNSET. WITH DRIER AIR ARRIVING...ANY SUB-VFR CONDITIONS SHOULD BE EVEN MORE LIMITED AS COMPARED TO REALITY FROM THIS MORNING. BEST CHANCES WILL BE AT KLWB. ON WEDNESDAY...ANY SUB-VFR CONDITIONS SHOULD IMPROVE RAPIDLY TO VFR BY MID-MORNING. EXTENDED AVIATION DISCUSSION... A BROAD TROUGH OF LOW PRESSURE WILL BE ACROSS THE EASTERN UNITED STATES THROUGH SUNDAY. HOWEVER...IT WILL START CENTERED OVER THE REGION...AND THEN RETROGRADE WEST TO NEAR THE MISSISSIPPI RIVER BY SUNDAY. THIS TRANSITION WILL ALLOW FOR BETTER CHANCES OF SHOWERS...AND PERHAPS A FEW THUNDERSTORMS...TO OCCUR ACROSS THE REGION AS ATLANTIC MOISTURE WILL BE ABLE TO WORK ITS WAY INTO THE AREA. ALONG WITH THIS MOISTURE WILL COME BETTER CHANCES FOR SUB- VFR CONDITIONS...ESPECIALLY UNDER ANY HEAVIER SHOWER OR STORM THAT FORMS...BUT ALSO DURING THE OVERNIGHT HOURS AS BOUNDARY LAYER MOISTURE GETS TRAPPED UNDER THE NOCTURNAL INVERSION. && .CLIMATE... JULY 30TH RECORD LOWS: ROANOKE......54...1997 BLUEFIELD....50...1981 DANVILLE.....60...1972/81/83/2013 LEWISBURG....46...2013 LYNCHBURG....52...1997 BLACKSBURG...50...1973/81 JULY 31ST RECORD LOWS: ROANOKE......49...1914 BLUEFIELD....49...1997 DANVILLE.....55...1966 LEWISBURG....48...1997 LYNCHBURG....49...1997 BLACKSBURG...44...1997 && .EQUIPMENT... THE NOAA WEATHER RADIO AT WYTHEVILLE VA...WZ2500...BROADCASTING ON A FREQUENCY OF 162.450 MHZ...IS OFF THE AIR...DUE TO PHONE LINE ISSUES. PHONE COMPANY IS WORKING ON IT. NO ESTIMATED TIME FOR RETURN TO SERVICE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF NEAR TERM...DS/NF/WP SHORT TERM...PH LONG TERM...AMS AVIATION...DS CLIMATE...DS/PH EQUIPMENT...DS

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