Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 011641 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1241 PM EDT SAT AUG 1 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN IN THE AREA INTO SUNDAY EVENING. AN UPPER DISTURBANCE PASSES ACROSS THE GREAT LAKES MONDAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 950 AM EDT SATURDAY... STILL MAINLY A TEMPERATURE FORECAST THIS AFTERNOON UNDER WEAK HIGH PRESSURE AND WEST/NW FLOW ALOFT. WEAK FRONT/TROUGH APPROACHING FROM THE NW MAY GENERATE A BIT OF CU NW AS SUPPORTED BY THE NAM CU RULE BUT EXPECTING MUCH OF THIS TO MIX OUT UNDER SUCH DRY AIR ALOFT OFF MORNING RAOBS. LATEST NAM AND HRRR ALSO GENERATING A FEW -SHRA FAR NORTH BUT LOOKS OVERDONE GIVEN SO MUCH DRY AIR DESPITE SOME DEWPOINT RISES SO LEAVING OUT MENTION THIS AFTERNOON. OTRW EXPECTING ANOTHER WARM AND DRY AFTERNOON WITH A LARGE DIURNAL SWING IN TEMPS GIVEN HEATING OF DRY AIR AND WEAK DOWNSLOPING OUT EAST. MORNING THICKNESS AND LATEST MOS DOES SUPPORT A LITTLE BUMP IN HIGHS SO RAISED A DEGREE OR TWO IN SPOTS ESPCLY EAST WHERE A FEW LOW 90S APPEAR LIKELY. PREVIOUS DISCUSSION AS OF 222 AM EDT SATURDAY... WEAK UPPER WAVE OVER THE OHIO VALLEY WILL SLIDE SOUTHEAST AND ERODE OVER THE PIEDMONT THIS AFTERNOON. AIRMASS REMAINS DRY SO NOT EXPECTING ANYTHING BUT A FEW CU/SC. THIS REINFORCES THE DRIER AIR. WITH PLENTY OF SUNSHINE WILL BE WARM/SEASONAL...HIGHS RANGING FROM THE UPPER 70S TO LOWER 80S MOUNTAINS...TO AROUND 90 EAST OF THE BLUE RIDGE...AND IN THE ROANOKE VALLEY NORTH TOWARD LEXINGTON. TONIGHT...SKIES STAY CLEAR WITH HIGH PRESSURE BUILDING OVERHEAD. COOP MOS TAKING TEMPS DOWN INTO THE UPPER 40S AT PLACES LIKE BURKES GARDEN AND JEFFERSON. NO THAT AGGRESSIVE WITH THE COOLER AIR BUT THINK A FEW HIGHER VALLEYS COULD REACH 50. MOST OF THE MOUNTAINS WILL DROP INTO THE 50S..WITH LOWER TO MID 60S EAST.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 250 AM EDT SATURDAY... UPPER LEVEL TROUGHING WILL HOLD IN PLACE THROUGH THE FIRST DAYS OF NEXT WEEK AS THE CENTER OF THE TROUGH MEANDERS AROUND THE HUDSON BAY REGION...KEEPING THE MID ATLANTIC SITUATED IN WESTERLY UPPER LEVEL WINDFLOW. HIGH PRESSURE IN THE LOW LEVELS WILL REMAIN SITUATED ACROSS THE CENTRAL APPALACHIANS ON SUNDAY...MAINTAINING DRY CONDITIONS UNDER MOSTLY CLEAR SKIES WITH A LIGHT NORTHWEST WIND. AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS THE GREAT LAKES ON MONDAY...POTENTIALLY BRINGING A FEW SHOWERS TO THE WESTERN RIDGES DURING THE AFTERNOON/EVENING. DOES NOT APPEAR TO BE ENOUGH SUPPORT FOR THIS ACTIVITY TO SURVIVE CROSSING THE CONTINENTAL DIVIDE HOWEVER...AS DOWNSLOPE WINDS CAUSE ANY TO DISSIPATE. A COLD FRONT WILL DROP SOUTH ON TUESDAY...PROMOTING GREATER INSTABILITY AS WINDS SHIFT SOUTHWESTERLY ACROSS OUR AREA. AS THE FRONT STALLS NORTH OF OUR AREA TUESDAY NIGHT...WILL MAINTAIN LOW RAIN CHANCES IN THE FORECAST AS WEAK IMPULSES RIDE ALONG THE FRONT INTO THE MID ATLANTIC FROM THE WEST. EXPECT A WARMING TREND THROUGH THE PERIOD AS TROUGHING ALOFT BECOMES LESS PRONOUNCED BY MID WEEK. EXPECT HIGHS IN THE LOW/MID 80S FOR THE MOUNTAINS SUNDAY...REACHING INTO THE UPPER 80S/LOW 90S FOR THE PIEDMONT. AFTERNOON HIGHS WILL WARM 1-2 DEGREES EACH DAY THEREAFTER. TEMPERATURES STILL SLIGHTLY BELOW NORMAL FOR SUNDAY NIGHT AS HIGH PRESSURE PROMOTES STRONG RADIATIONAL COOLING...HOWEVER OVERNIGHT TEMPERATURES WILL MODERATE TOWARD MID WEEK TO MID/UPPER 60S AREAWIDE AS CLOUD COVER AND SOUTHWESTERLY WINDFLOW RETURNS. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 250 AM EDT SATURDAY... EAST-WEST BAROCLINIC ZONE WILL THEN BECOME ESTABLISHED OVER THE FORECAST AREA FOR THE LONG-TERM PERIOD...WITH UPSTREAM SHORT WAVES AND/OR MESOSCALE VORTICITY CENTERS FROM DECAYING OLD MIDWEST CONVECTIVE COMPLEXES PROVIDING SUFFICIENT ENERGY/SUPPORT TO MAINTAIN THREAT FOR SCATTERED CONVECTION THROUGH THE PERIOD. GRADUALLY RISING DEW POINTS WILL SLOWLY COMPRESS THE DIURNAL TEMPERATURE CURVE BACK TO AROUND 20F AS SULTRY AIRMASS SLOWLY REESTABLISHES ITSELF OVER THE AREA. EXPECT OVERNIGHT LOWS DURING THE PERIOD TO RANGE FROM THE 60S IN THE MOUNTAINS TO AROUND 70 IN THE PIEDMONT...WITH HIGHS RANGING FROM MAINLY 80S IN THE MOUNTAINS TO LOWER-MID 90S ACROSS THE PIEDMONT. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 1230 PM EDT SATURDAY... EXPECTING CU FIELD ACROSS THE NW TO GRADUALLY EXPAND SOUTHEAST THIS AFTERNOON AHEAD OF A WEAK SURFACE TROUGH THAT WILL CROSS THE REGION BY THIS EVENING. THIS MAY RESULT IN AREAS OF BKN 4-6K FT CIGS AT TIMES FROM KLWB TO KBLF/KBCB BUT NOT EXPECTING MUCH IN THE WAY OF SHOWERS GIVEN LOW LEVEL DRYNESS. SHOULD SEE THIS CLOUDINESS FADE WITH LOSS OF HEATING EXCEPT PERHAPS ACROSS THE FAR WESTERN RIDGES WHERE UPSLOPE WILL KICK IN AND POSSIBLY KEEP SOME SCATTERED STRATO-CU LINGERING THIS EVENING. OTRW VFR CONDITIONS ARE EXPECTED TO PREVAIL THIS AFTERNOON THROUGH SUNDAY. THE ONLY OTHER EXCEPTION WILL BE SOME BRIEF...EARLY MORNING PATCHY RIVER OR MOUNTAIN VALLEY FOG AT KLWB BUT IFFY AS TO HOW LOW VSBYS WILL GO GIVEN LIKELY PATCHY/ISOLATED NATURE TO THE FOG. THUS KEPT TREND TOWARD A PERIOD OF MVFR AT KLWB BUT LITTLE ELSEWHERE. ANY FOG THAT DOES DEVELOP WILL QUICKLY MIX OUT BY 13Z/9AM SUNDAY. SHOULD SEE LESS IN THE WAY OF CU ON SUNDAY WITH REINFORCING DRY AIR THAT WILL LIMIT ANY RETURN MOISTURE TO LATE IN THE DAY AND MAINLY SW OF THE TAF SITES. EXTENDED AVIATION FORECAST... MOSTLY VFR OUTSIDE OF ANY CONVECTION THROUGH THE PERIOD. A FRONT WILL SET UP IN THE MID ATLANTIC WHICH COULD BRING A FEW SHRA/TSRA BY TUESDAY...WITH PERHAPS A BIT MORE COVERAGE LATER WEDNESDAY AT THIS POINT. THUS THE THREAT OF SUB-VFR REMAINS LOW UNTIL AROUND MIDWEEK...EXCEPT FOR THE TYPICAL FOG POTENTIAL AT KLWB/KBCB EACH MORNING BETWEEN 09-13Z.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...JH/WP SHORT TERM...NF LONG TERM...WERT AVIATION...JH/WP

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