Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 220543 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 143 AM EDT TUE APR 22 2014 .SYNOPSIS... SURFACE HIGH PRESSURE EXTENDING ACROSS THE REGION FROM THE MID ATLANTIC COAST WILL WEAKEN AND PASS OFFSHORE OVERNIGHT. A COLD FRONT IN THE MIDWEST WILL SWEEP SOUTHEAST THROUGH THE AREA ON TUESDAY...PRECEDED AND ACCOMPANIED BY SCATTERED SHOWERS AND THUNDERSTORMS. HIGH PRESSURE IS EXPECTED TO RETURN TO THE AREA ON WEDNESDAY...BRINGING BLUSTERY AND COOLER WEATHER. && .NEAR TERM /THROUGH TODAY/... AS OF 915 PM EDT MONDAY... ADJUSTED TEMPERATURES...DEW POINTS AND POPS FOR TONIGHT INTO TUESDAY MORNING. LOCAL RNK WRFARW BRINGS ISOLATED TO SCATTERED SHOWERS IN THE FAR WEST AROUND 08Z TUESDAY. THE HRRR IS A LITTLE SLOWER WITH THE CONVECTION BRING IN SCATTERED SHOWERS IN AROUND 10Z. THE NAM AND ECMWF HAVE SIMILAR TIMING OF PRECIPITATION...WITH THE GFS A BIT QUICKER WITH CONVECTION. REGIONAL WSR-88D IMAGES DEPICTED A FEW ECHOES MOSTLY ALOFT TO OUR WEST FIGHTING VERY DRY AIR AS SEEN IN THE EVENING 00Z/8PM RNK SOUNDING. FIRST FEW ROUND OF SHOWERS WILL TAKE SOME TIME TO SATURATE THE COLUMN. BY DAYBREAK EXPECTED SCATTERED SHOWERS ACROSS THE MOUNTAINS IN ADVANCE OF APPROACHING FRONTAL ZONE. LOW TEMPERATURES WILL RANGE FROM THE MID 40S IN THE COLDER VALLEYS TO MID 50S ALONG THE WESTERN RIDGES. THE COLD FRONT WILL TRAVEL SOUTHEAST THROUGH THE AREA ON TUESDAY...PRECEDED AND ACCOMPANIED BY SCATTERED SHOWERS AND THUNDERSTORMS. THERE STILL ENOUGH INSTABILITY TO SUPPORT THE MENTION OF THUNDERSTORMS LATE MORNING INTO THE AFTERNOON. WEAK WESTERLY FLOW/SHEAR AND LIMITED LAPSES RATES EXPECTED WITH STORMS. HIGH TEMPERATURES TUESDAY WILL VARY FROM THE LOWER 60S IN THE NORTHWEST MOUNTAINS TO AROUND 80 DEGREES IN THE PIEDMONT. AS OF 605 PM EDT MONDAY... ADJUSTED TEMPERATURES AND DEW POINTS ACCORDING TO LATEST OBS AND MODEL TRENDS. THIS EVENING RIDGING ACROSS THE REGION WILL WEAKEN TONIGHT INTO TUESDAY MORNING...AS 1019 SURFACE HIGH PRESSURE CENTER LIFTS NORTHEAST. A COLD FRONT TO OUR WEST WILL APPROACH LATE TONIGHT...WITH A GRADUAL RETURN OF LOW LEVEL MOISTURE. LOW TEMPERATURES OVERNIGHT ARE A CHALLENGE WITH THE POTENTIAL FOR BIG DROPS IN THE EAST WITH MOSTLY CLEAR SKIES AND RISING TEMPERATURES OR STEADY IN THE WEST WITH INCREASING CLOUD COVER. WILL MONITOR THIS EVENING FOR ADDITIONAL CHANGES LATER TONIGHT. HAVE A GOOD EVENING. AS OF 200 PM EDT MONDAY... RIDGING ACROSS THE REGION EARLY THIS EVENING WILL QUICKLY WEAKEN OVERNIGHT AS THE SURFACE HIGH PULLS OUT TO THE NE AND UPSTREAM 5H HEIGHT FALLS DAMPEN OUT THE MID LEVEL SHORTWAVE RIDGE. THIS SHOULD ALLOW FOR A GRADUAL RETURN OF LOW LEVEL MOISTURE OVERNIGHT ALONG WITH AN INCREASE IN HIGH/MID CLOUDS AHEAD OF THE FRONT ESPCLY AFTER MIDNIGHT. HOWEVER THE MID LEVELS REMAIN QUITE DRY SO THINKING THAT MOST -SHRA SHOULD STAY JUST WEST OF THE CWA THROUGH DAYBREAK AT THIS POINT. OTRW MAINLY CLEAR EARLY THEN BECOMING MOSTLY CLOUDY WEST AND PC EAST BY MORNING. LOWS A BIT TRICKY WITH POTENTIAL TO SEE QUICK TEMP FALLS WHILE CLEAR THIS EVENING...THEN A STEADYING OUT SCENARIO OVERNIGHT ESPCLY MOUNTAINS AS CLOUDS ARRIVE. THEREFORE LEANED CLOSER TO THE WARMER MET MOS WEST ESPCLY RIDGES...AND WITH THE COLDER MAV EAST WHERE SHOULD STAY CLEAR LONGER. STILL QUESTIONS IN REGARDS TO CONVECTIVE POTENTIAL WITH THE PASSING COLD FRONT TUESDAY AFTERNOON AND THE DEGREE OF QPF THAT MIGHT OCCUR OUTSIDE OF THE WESTERN SLOPES. LATEST GUIDANCE HAS TRENDED A BIT SLOWER IN PUSHING INITIAL PRE-FRONTAL BAND OF SHRA OVER THE WESTERN MOUNTAINS TUESDAY MORNING WHICH WOULD ALLOW MORE TIME FOR MOISTURE ADVECTION AND INSTABILITY TO DEVELOP OUT EAST CLOSER TO THE LEE TROUGH. HOWEVER APPEARS LOTS OF CLOUDS TO ARRIVE EARLY OVER THE WEST WHICH COULD LIMIT HEATING AND CAUSE A JUMP IN FADING SHRA OVER THE WEST TO A DEEPER BAND OF SHRA/TSRA TO THE EAST OF THE CWA GIVEN DEEPENING DOWNSLOPE EAST OF THE BLUE RIDGE. FOR NOW WILL GO A BIT SLOWER...SIMILAR TO THE SPC WRF SOLUTION IN BRINGING SHRA INTO THE WEST BY MID/LATE MORNING UNDER A FAINT WAVE ALOFT...THEN WEAKENING BEFORE PERHAPS REDEVELOPING ACROSS THE FAR EASTERN CWA BY MID AFTERNOON UNDER THE LEE TROUGH AS SEEING JUST ENOUGH LOW LEVEL BACKING FOR THIS TO OCCUR. OTRW SEVERE THREAT APPEARS LOW GIVEN RATHER WEAK WESTERLY FLOW/SHEAR AND LAPSES...WITH ONLY THE DRIER LOW LEVELS POSSIBLY ENHANCING LOCALIZED WINDS IF ANY CELLS CAN GET ORGANIZED/STRONG ENOUGH AND A SPLIT OUT EAST DOESN`T OCCUR. THUS CONTINUED THE TREND OF GOING WITH A PERIOD OF LIKELY POPS FROM NW TO SE DURING THE DAY FOR NOW WITH LESS SE GIVEN WEST WINDS AND HIGHER PROBS NW WHERE UP TO A HALF INCH OF QPF COULD OCCUR. ELSW APPEARS LOW QPF WITH ONLY A TENTH OF AN INCH OR LESS EAST AND PERHAPS UP TO A QUARTER INCH ELSW WEST OF THE BLUE RIDGE. HIGH TEMPS LOOK TO PUSH 80 AHEAD OF THE BOUNDARY PIEDMONT...WITH 70S BLUE RIDGE BUT ONLY MID/UPPER 60S WEST WHERE CLOUDS/-SHRA COULD KEEP VALUES EVEN COOLER PENDING EARLIER TIMING. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... AS OF 300 PM EDT MONDAY... BY 00Z (7 PM EDT) TUESDAY THE COLD FRONT WILL BE WELL EAST OF OUR FORECAST AIR WITH STRONG NORTHWEST WINDS GENERATING A FEW UPSLOPE RAIN SHOWERS. NORTHWEST WINDS WILL BE QUITE GUSTY WITH STRONG PRESSURE RISES MOVING THROUGH BETWEEN 03Z-09Z. BUFKIT TIME CROSS SECTION SHOWS 50 KTS ABOVE THE INVERSION AOA 5KT FEET. BUMPED UP WINDS...ESPECIALLY IN THE MOUNTAINS TUESDAY NIGHT...BUT FORECAST VALUES STILL BELOW WIND ADVISORY CRITERIA. COLD AIR ADVECTION WEDNESDAY MORNING SHOULD ALLOW TEMPS TO DROP TO COOLER GFS GUIDANCE IN THE MOUNTAINS. WINDS GRADUALLY RELAX WEDNESDAY AS SFC HIGH PRESSURE BUILDS FROM THE GREAT LAKES. GOOD DRYING ALSO EXPECTED WEDNESDAY...WITH RH VALUES FALLING INTO THE 20S FOR MOST AREAS. LEANED TOWARD THE WARMER GFS GUIDANCE EAST OF THE BLUE RIDGE...WITH DOWNSLOPING WINDS...WITH A FEW DEGREES SHAVED OFF GUIDANCE IN THE MOUNTAINS WHERE COLD AIR ADVECTION LINGERS. GOOD RADIATIONAL COOLING DEVELOPING LATE WEDNESDAY NIGHT AS THE SFC RIDGE AXIS FORECAST TO BE OVERHEAD BY EARLY THURSDAY MORNING. WITH PLENTY OF DRY AIR IN PLACE...SOME AREAS OF FROST POSSIBLE IN THE MOUNTAINS. RIDGING AT THE SFC AND ALOFT...WITH A RETURN TO A SOUTH/SOUTHWEST FLOW WILL RESULT IN WARMER TEMPERATURES...WITH MOST AREAS REACHING OR EXCEEDING 70. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 300 PM EDT MONDAY... DESPITE AN INCREASE IN CLOUDS AND A CHANCE FOR SHOWERS AND STORMS ASSOCIATED WITH A COLD FRONT FRIDAY...STRONG WARM AIR ADVECTION WITH A DEEP SOUTHWEST/WEST FLOW...SHOULD CONTINUE THE TREND FOR MODERATING TEMPS. THE PATTERN FRIDAY APPEARS VERY SIMILAR TO TUESDAY`S...WITH A FAST MOVING COLD FRONT MOVING INTO THE WEST EARLY ON FRIDAY AND EXITING DURING THE AFTERNOON. ONCE AGAIN...LOW LEVEL MOISTURE AND INSTABILITY WILL BE RACING NORTH TO INTERCEPT THE FRONT IN THE FAR EASTERN PORTION OF THE FORECAST AREA. THIS WILL BE WHERE THE BEST CHANCE FOR THUNDERSTORMS WILL TAKE PLACE. WHILE THE FRONT PASSES THROUGH FRIDAY AFTERNOON...THE STRONG COLD AIR ADVECTION IS DELAYED UNTIL LATER SATURDAY...SO ANOTHER WARM DAY IS ANTICIPATED EAST OF THE BLUE RIDGE. AFTER SATURDAY THERE ARE CONSIDERABLE DIFFERENCES IN THE LONG RANGE MODELS WITH THE GFS...CANADIAN AND GFS ENSEMBLES ALL KEEPING A SFC FRONT TO OUR SOUTH WITH A DRY NORTHWEST FLOW. MEANWHILE...THE 00Z/21 ECMWF KEEPS OUR AREA IN THE WARM SECTOR WITH A MOIST SOUTHERLY FLOW. THE GFS HAS SHOWN MORE RUN TO RUN CONSISTENCY AND THE LATEST GLOBAL WIND OSCILLATION (GWO) PLOT FAVORS AN EASTERN U.S. TROF. THEREFORE...NUDGED TEMPS DOWN A FEW DEGREES AND KEPT AREA FREE OF PRECIPITATION THROUGH THE WEEKEND. A QUICK LOOK AT THE 12Z ECMWF SHOWS A TREND TOWARD THIS COOLER SOLUTION. AS A SFC WARM FRONT BEGINS TO LIFT NORTH AND LOW LEVEL MOISTURE RETURNS...SCATTERED SHOWERS POSSIBLE IN THE MOUNTAINS. CONFIDENCE ON THE LOCATION OF THE WARM FRONT AND CHANCES FOR PRECIP ARE LOW. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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AS OF 140 AM EDT MONDAY... SCATTERED SHOWERS ACRS THE OHIO VALLEY EARLY THIS MORNING WILL SHIFT EAST WITH APPROACHING COLD FRONT LATER THIS MORNING. LOCALIZED MVFR FLIGHT RESTRICTIONS LIKELY WITH PASSING SHOWERS WITH BEST CHANCE OF MVFR CIGS AND/OR VSBYS AT BLF/LWB WITH ONLY LIGHTER SHOWERS OUT TO THE BLUE RIDGE LATER IN THE MORNING. ISOLATED TO SCATTERED SHRA/TSRA POSSIBLE ALONG THE LYH-DAN CORRIDOR THIS AFTERNOON. MEDIUM CONFIDENCE IN CEILING...VISIBILITIES AND WINDS DURING THE TAF PERIOD AS CONDITIONS LIKELY TO BE CHANGEABLE. THE FRONT WILL EXIT THE REGION BY TUESDAY NIGHT...RESULTING IN A RETURN TO VFR WEATHER AND GUSTY NW WINDS TUESDAY NIGHT INTO WEDNESDAY...EXCEPT FOR THE POTENTIAL OF SOME MVFR CIGS LINGERING OVER THE FAR WESTERN UPSLOPE SITES IN SE WEST VA. EXTENDED AVIATION DISCUSSION... HIGH PRESSURE WILL THEN BUILD INTO AND OVER THE REGION ON THURSDAY...WITH WIDESPREAD VFR LIKELY. ANOTHER FAST MOVING COLD FRONT WILL ARRIVE ON FRIDAY...WITH A BRIEF PERIOD OF MVFR RESTRICTIONS POSSIBLE AS SHOWERS/ISOLATED STORMS MOVE EAST WITH THE FRONT THROUGH THE AREA.
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&& .FIRE WEATHER... AS OF 927 PM EDT MONDAY... MOISTURE WILL SLOWLY RECOVER OVERNIGHT AND THEN MOISTEN ABOVE 60-70 PERCENT BY EARLY TUESDAY AHEAD OF THE APPROACHING COLD FRONT. THE FRONT WILL CROSS THE REGION ON TUESDAY WITH QPF RANGING FROM ONE QUARTER TO ONE HALF INCH IN PARTS OF WEST VA...TO A TENTH OR QUARTER INCH BLUE RIDGE...TO LIKELY LESS THAN A TENTH OF AN INCH PIEDMONT. STRONG NW WINDS FOLLOWING THE FRONT MAY BE OF ADDED CONCERN ON WEDNESDAY WITH GUSTS TO 25 TO 35 MPH POSSIBLE ALONG WITH ANOTHER QUICK DROP IN HUMIDITY WEDNESDAY AFTERNOON. THIS MAY LEAD TO ENHANCED FIRE DANGER ESPECIALLY IF LESS WETTING RAINFALL IS REALIZED WITH THE FRONTAL PASSAGE ON TUESDAY. THE NEXT BEST OPPORTUNITY FOR PRESCRIBED BURNS WHERE GOOD DRYING CONDITIONS WILL EXIST...AND WHERE TRANSPORT WINDS WILL BE MORE FAVORABLE DUE TO BETTER TRANSPORT AND CONSISTENCY OF DIRECTION WILL OCCUR ON THURSDAY AT THIS POINT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/WERT NEAR TERM...JH/KK SHORT TERM...PH LONG TERM...PH AVIATION...KK/PC FIRE WEATHER...JH/KK/WERT

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