Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 011835 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 235 PM EDT SAT AUG 1 2015 .SYNOPSIS...
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HIGH PRESSURE WILL BUILD EAST ACROSS THE REGION OVERNIGHT AND REMAIN IN PLACE SUNDAY INTO SUNDAY NIGHT. AN UPPER DISTURBANCE PASSES ACROSS THE GREAT LAKES MONDAY FOLLOWED BY A COLD FRONT THAT WILL DROP SOUTH INTO THE AREA TUESDAY INTO WEDNESDAY.
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&& .NEAR TERM /THROUGH SUNDAY/...
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AS OF 200 PM EDT SATURDAY... WEAK SURFACE TROUGH CROSSING THE BLUE RIDGE THIS AFTERNOON WILL BRING A REINFORCING SHOT OF DRIER/COOLER AIR OVERNIGHT AS HIGH PRESSURE BUILDS EAST AND SETTLES ABOUT OVERHEAD THE WESTERN MOUNTAINS BY DAWN SUNDAY. THIS SHOULD ALLOW ANY RESIDUAL CU TO FADE WITH LOSS OF HEATING AS DRIER AIR ADVECTS IN WHILE ALSO HELPING WINDS DIMINISH THIS EVENING...BUT PERHAPS NOT ON THE RIDGES UNTIL AFTER MIDNIGHT. THIS ALONG WITH EVEN COOLER AIR AT 85H THAN SEEN BEFORE LIKELY TO MAKE FOR GREAT RADIATIONAL COOLING WEST LATE WITH A LIGHT NORTH/NE BREEZE LINGERING OUT EAST IN SPOTS. LATEST MOS SIMILAR TO PREVIOUS WITH MAINLY LOW/MID 60S EAST AND COOL 50S TO AROUND 60 WEST. HOWEVER A FEW UPPER 40S POSSIBLE DEEPEST WESTERN VALLEYS PENDING ANY LATE NIGHT RIVER FOG AND RESIDUAL WESTERN SLOPE STRATO-CU THAT MAY LINGER. SURFACE HIGH WILL BE OVERHEAD FOR MUCH OF SUNDAY ALLOWING FOR ANOTHER WARM BUT DRY DAY WITH OVERALL LOW HUMIDITY UNDER MAINLY SUNNY SKIES. A WEAK MID LEVEL WAVE RIDING THROUGH THE BASE OF THE 5H TROUGH COULD PRODUCE SOME LOW CLOUDS NW EARLY BEFORE MIXING OUT. ALSO MAY SEE JUST ENOUGH RETURN SW FLOW AS THE HIGH SLIDES EAST LATE TO PROMPT A BIT MORE CU OVER SW SECTIONS BUT WITHOUT ANY POP MENTION FOR NOW GIVEN DRYNESS. SHOULD BE ANOTHER LARGE DIURNAL SWING TO TEMPS AS 850 MB VALUES START TO REBOUND WHILE HIGHS AIDED BY HEATING OF DRY AIR AND WEAK EASTERN DOWNSLOPE. THIS SIMILAR TO THE PAST COUPLE OF DAYS SO STAYING CLOSE TO PERSISTENCE WITH MOSTLY 80S MOUNTAINS AND UPPER 80S/LOW 90S EAST.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
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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. 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...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.
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&& .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 /19Z SATURDAY THROUGH THURSDAY/... 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. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/WP NEAR TERM...JH SHORT TERM...NF LONG TERM...WERT AVIATION...JH/WP

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