Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 290608 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 208 AM EDT TUE JUL 29 2014 .SYNOPSIS... AN UPPER TROUGH OF LOW PRESSURE WILL REMAIN CENTERED OVER THE EAST COAST THROUGH THE MIDDLE OF THE WEEK. LIKEWISE...COOL HIGH PRESSURE WILL SETTLE OVER THE REGION THROUGH WEDNESDAY. DURING THE LATTER HALF OF THE WEEK AND HEADING INTO THE WEEKEND...THE UPPER TROUGH WILL RETROGRADE WESTWARD...AND ALLOW FOR AN INCREASE IN MOISTURE...MODERATING TEMPERATURES...AND POTENTIAL FOR SHOWERS AND STORMS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 100 AM EDT TUESDAY... STILL A FEW SHOWERS ACROSS THE AREA THIS MORNING...WITH ONE BAND MAKING OVER THE NEW RIVER VALLEY FROM SOUTHEAST WEST VIRGINIA. RAPID UPDATE MODELS INDICATING THAT A FEW SPRINKLES WILL LINGER THROUGH THE NIGHT HERE AND THERE...NOT DOING MUCH MORE THAN WETTING THE SURFACE. REGARDLESS...WILL EXTEND SLIGHT RAIN CHANCES THROUGH AROUND DAYBREAK. WINDS HAVE CALMED IN THE VALLEYS...SO PATCHY FOG MAY FORM IN TYPICAL LOCATIONS AROUND RIVERS/LAKES BY DAWN WITH COOLER AIR RUSHING IN. SKIES WILL REMAIN SOMEWHAT CLOUDY OVER THE UPSLOPE REGIONS OF SOUTHEAST WEST VIRGINIA OVERNIGHT BUT SCATTERED OUT TO THE EAST. FORECAST LOWS APPEAR ON TRACK...FROM THE LOWER 50S ACROSS THE MTNS TO AROUND 60 OUT EAST. LATER TODAY...OUR COOL PATTERN WILL CONTINUE WITH THE AXIS OF THE UPPER TROUGH STILL OVER OUR REGION...AND THE CENTER OF SURFACE HIGH PRESSURE WILL APPROACH FROM THE WEST. EMBEDDED WITH THE MAIN UPPER TROUGH PATTERN...MODEL GUIDANCE OFFER A SOLUTION WITH A WEAK DISTURBANCE WITHIN THE MAIN FLOW CROSSING MAINLY THE SOUTHERN HALF OF THE AREA ON TUESDAY. WILL CONTINUE TO ALLOW FOR ISOLATED SHOWERS IN THE FORECAST ACROSS THE SOUTHWESTERN PART OF THE AREA...IN THE PATH OF THE DISTURBANCE AND WITHIN A ZONE OF WEAK UPSLOPE 850 MB FLOW. HIGH ON TUESDAY ARE EXPECTED TO AVERAGE AROUND FIVE DEGREES COOLER THAN THOSE REALIZED TODAY. LOW TO MID 70S ARE FORECAST ACROSS THE MOUNTAINS WITH UPPER 70S TO NEAR 80 ACROSS THE PIEDMONT. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/... AS OF 345 PM EDT MONDAY... BY WEDNESDAY MORNING SURFACE HIGH PRESSURE IS CENTERED OVER THE FORECAST AREA. A VERY WEAK PRESSURE GRADIENT REMAINS IN PLACE THROUGH THURSDAY. PRECIPITABLE WATER VALUES GRADUALLY INCREASE BACK UP INTO THE 1.0 TO 1.5 INCH RANGE BY LATE THURSDAY. BUFKIT FORECAST SOUNDINGS FOR WEDNESDAY SHOW ENOUGH MIXING TO BRING DEW POINTS DOWN INTO THE 40S FOR MUCH OF THE AREA DURING THE AFTERNOON. WILL STAY CLOSE TO COOLER GUIDANCE FOR LOWS ON BOTH TUESDAY NIGHT AND WEDNESDAY NIGHT. RECORD LOWS ARE STILL POSSIBLE TUESDAY NIGHT WITH LOWS 5 TO 15 DEGREES BELOW NORMAL. && .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 /06Z TUESDAY THROUGH SATURDAY/...
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AS OF 200 AM EDT TUESDAY... WEATHER CONCERNS FOR THE 29/06Z TAF PERIOD WILL BE MINOR AND FOCUSED MAINLY FOR THE MOUNTAINS. STARTING THE TAF PERIOD WITH IFR CEILINGS AT KBLF DUE TO THE NORTHWESTERLY UPSLOPE FLOW BANKING MOISTURE IN THE NEARBY TERRAIN. EXPECT VFR CONDITIONS MOST OTHER AIRPORTS...AS WINDS ARE JUST STRONG ENOUGH TO KEEP THE ATMOSPHERE MIXED WHICH SHOULD PREVENT MORE THAN ISOLATED POCKETS OF FOG. SHOWERS PASSING ACROSS THE MOUNTAINS THROUGH THE NIGHT MAY ALSO BRIEFLY LOWER VISIBILITIES. MOUNTAIN MVFR/IFR CEILINGS WILL LIFT AND SCATTER DURING LATE MORNING WITH DAYTIME HEATING. EXPECT SCT TO BKN STRATOCU LAYER TO DEVELOP BY EARLY AFTERNOON...GREATER COVERAGE IN THE MOUNTAINS... WITH CLOUD BASES RANGING 3KFT IN THE MOUNTAINS TO 5KFT FURTHER EAST. SPOTTY SHOWER ACTIVITY WILL ALSO PASS ACROSS THE AREA DURING THE AFTERNOON AS WEAK DISTURBANCES MOVE ACROSS IN THE NORTHWEST FLOW. A MUCH WEAKER PRESSURE GRADIENT TODAY WILL KEEP WINDS 5KTS TO 10KTS DURING THE AFTERNOON FOR THE TAF SITES. EXTENDED AVIATION DISCUSSION... PERSISTENT TROUGH PATTERN IN THE EAST WILL GRADUALLY RETROGRADE WEST BY THE END OF THE WEEK. MAINLY VFR CONDITIONS ARE EXPECTED THROUGH AT LEAST THURSDAY SAVE FOR SOME LATE NIGHT/EARLY MORNING PATCHY MVFR FOG IN THE MOUNTAIN AND RIVER VALLEYS. AFTER THURSDAY...WITH THE TROUGH AXIS FARTHER WEST...THIS WILL ALLOW FOR A RETURN OF ATLANTIC MOISTURE AND A GREATER ABUNDANCE OF SHOWERS...AND POTENTIALLY STORMS...IN THE FORECAST HEADING INTO THE WEEKEND. THIS ALSO WILL ALLOW FOR INCREASED CHANCES OF SUB-VFR CONDITIONS WITHIN THE AREA OF THE SHOWERS...AND THEN AGAIN OVERNIGHT IN THE FORM OF LIGHT FOG OR STRATUS AS BOUNDARY MOISTURE GETS TRAPPED UNDER THE NOCTURNAL INVERSION.
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&& .CLIMATE... JULY 29TH RECORD LOWS: ROANOKE......52...1925 BLUEFIELD....55...2013 DANVILLE.....58...1968 LEWISBURG....46...2013 LYNCHBURG....53...1920 BLACKSBURG...50...1983 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...DS NEAR TERM...DS/NF/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...NF/WP CLIMATE...DS/PH EQUIPMENT...DS

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