Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 290000 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 700 PM EST FRI NOV 28 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION TONIGHT INTO SATURDAY... BEFORE SLIPPING OFF TO OUR SOUTHEAST. THIS WILL BRING FAIR WEATHER WITH A WARMING TREND TO THE APPALACHIANS AND CENTRAL MID ATLANTIC REGION THROUGH SUNDAY. A SLOW MOVING COLD FRONT WILL THEN MOVE THROUGH THE REGION LATE MONDAY INTO MONDAY NIGHT...BRINGING PRECIPITATION AND A BRIEF COOL DOWN FOR TUESDAY...FOLLOWED BY SEASONABLE WEATHER BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
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AS OF 650 PM EST FRIDAY... NO SIGNIFICANT CHANGES NEEDED TO THE GRIDS AT THIS TIME...JUST SOME MINOR MODIFICATIONS TO T/TD TO BRING INTO LINE WITH CURRENT READINGS. OTHERWISE...FORECAST IS ON TRACK AND LOW CLOUDS HAVE CLEARED IN WESTERN AREAS. AS OF 320 PM EST FRIDAY... TRANQUIL CONDITIONS EXPECTED IN THE NEAR TERM AS HIGH PRESSURE ALONG THE EASTERN SEABOARD PREDOMINATES. THE UPPER FLOW IS MUCH MORE ZONAL THE NEXT 24 HOURS WHICH WILL ALLOW MUCH MILDER AIR TO SPILL EASTWARD FROM THE CENTRAL PLAINS TOWARD THE CENTRAL/SOUTHERN APPALACHIANS. H85 TEMPS REBOUND FROM -10C READINGS OF THIS MORNING TO +5C BY MIDDAY TOMORROW. TEMPS TONIGHT WILL BE CHILLY AGAIN BUT FIGHTING WARM ADVECTION AS WELL AS HIGH CLOUDS FROM A SHORT-WAVE PASSING WELL TO THE NORTH. WENT WITH MODEL BLEND YIELDING LOWS FAIRLY UNIFORM ACROSS THE CWA FROM LOW TO MID-20S. COULD BE A LITTLE COOLER IN THE SOUTH WHERE CLOUDS LEAST LIKELY. AFTER THE RECENT CHILLY SPELL SATURDAY WILL SEEM COMPARATIVELY MILD WITH HIGHS RANGING FROM MID- 40S TO LOW 50S WHICH IS STILL BELOW CLIMO BUT ABOUT 10F WARMER THAN TODAY. CLOUDS FROM THE NORTHERN SHORT-WAVE WILL BE ON THE DECREASE THROUGH THE AFTERNOON WHICH WILL MAKE FOR MOSTLY SUNNY SKIES BY LATER IN THE DAY AND GOOD WEATHER FOR OUTDOOR ACTIVITIES.
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&& .SHORT TERM /7 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... AS OF 320 PM EST FRIDAY... QUIET WEATHER WITH A WARMING TREND THROUGH THE WEEKEND AS HIGH PRESSURE SLIDES OFF TO OUR SOUTHEAST AND WINDS BECOME SWLY. LOW LEVEL JET WILL BE SETTING UP JUST TO OUR WEST AND EXPECT THIS WILL MAKE FOR SOME BLUSTERY CONDITIONS AT THE HIGHER ELEVATIONS THROUGH THE WEEKEND. WITH QUASI ZONAL UPPER PATTERN IN PLACE...COLD FRONT APPROACHING FROM THE NORTHWEST HAS NO BIG PUSH TO IT AND IT WILL TAKE ITS TIME MOVING THROUGH THE REGION ON MONDAY. THIS WILL LEAD TO SLOWLY INCREASING POPS FORM THE NORTHWEST SUNDAY NIGHT INTO MONDAY WITH BEST CHANCE OF PRECIP HOLDING OFF UNTIL A WAVE ALONG THE FRONT RIPPLES THROUGH MONDAY NIGHT INTO TUESDAY. GFS IS MOST AGGRESSIVE WITH THE PRECIP CHANCES WITH THE WAVE WITH OTHER GUIDANCE NOT QUITE SO ENTHUSIASTIC. HIGH CHC POPS SHOULD COVER THE SITUATION UNTIL LATER RUNS CAN CONVERGE ON A SOLUTION. VERY STRONG HIGH PRESSURE WILL BUILD INTO NEW ENGLAND AND THEN FORCIBLY WEDGE DOWN THE ERN SEABOARD MONDAY NIGHT AND TUESDAY WITH MUCH COLDER AIR MOVING IN. THIS WILL LIKELY CREATE SOME PTYPE ISSUES AS THE COLD AIR ARRIVES. EXACT DEPTH AND MAGNITUDE OF THE SFC BASED COLD LAYER ARE NOT CLEAR AT THIS POINT...BUT EXPECT GREATEST LIKELIHOOD WILL BE FORE SOME POCKETS OF FREEZING RAIN...SO WILL INDICATE THIS IN THE GRIDS. GUIDANCE HAS TRENDED COLDER BUT HAVE TRIMMED A BIT MORE IN ANTICIPATION OF A STRONG WEDGE SITUATION. && .LONG TERM /TUESDAY THROUGH FRIDAY/...
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AS OF 320 PM EST THURSDAY... AN UPPER LEVEL TROUGH/SHORT WAVE WILL GLIDE OVER THE FORECAST AREA TUESDAY AFTERNOON...EXITING THE PIEDMONT IN THE EVENING. RAIN FROM THIS TROUGH WILL ENHANCE THE WEDGE COMING ACROSS THE MID ATLANTIC REGION. BY WEDNESDAY MORNING...THE WEDGE COULD BE AS FAR SOUTH AS THE FLORIDA PANHANDLE. BULK OF THE MOISTURE WILL EXIT WITH THE TROUGH...HOWEVER WARM MOIST AIR WILL BEGIN TO OVERRUN THE COOLER LOW LEVELS TUESDAY NIGHT INTO WEDNESDAY. THICK LOW CLOUDS AND FOG WILL LIKELY ENGULF THE FORECAST AREA TUESDAY NIGHT...LINGERING INTO THURSDAY MORNING. WARM MOIST AIR ADVECTING IN ALOFT AND INCREASING ISENTROPIC LIFT TUESDAY NIGHT INTO WEDNESDAY MORNING...MAY BE ENOUGH TO PRODUCE LIGHT PRECIPITATION ALONG AND EAST OF THE BLUE RIDGE. CONSIDERING HOW DRY THE PARENT HIGH IS OVER NEW ENGLAND...MEASURABLE PRECIPITATION MAY BE LIMITED TO THE EASTERN SLOPES OF THE BLUE RIDGE. CONFIDENCE IS NOT HIGH...THEREFORE WILL KEEP POPS UNDER 30 PERCENT. PRECIPITATION TYPE WILL BE THE CHALLENGE AS DRY COOLER LOW LEVEL AIR WILL ADVANCE SOUTH WITH WARM MOIST AIR ALOFT ADVECTING NORTH. LOW LEVEL THICKNESSES ARE AROUND 1300M OVER THE ALLEGHANY HIGHLANDS AND SOUTHERN SHENANDOAH VALLEY TUESDAY NIGHT...THEN GRADUALLY INCREASE GOING INTO WEDNESDAY MORNING. 85H TEMPERATURES AROUND 0C ALONG THE SOUTHWEST VIRGINIA BLUE RIDGE...+2C ACROSS THE NORTH CAROLINA HIGHLANDS. THESE 85H TEMPERATURES ALSO WARM GOING INTO WEDNESDAY MORNING. VIEWING MODEL SOUNDINGS...THE COLD SUB-FREEZING AIR IS AROUND 4000 FEET THICK. SOUNDING PROFILES ALSO SUGGESTING ANY MEASURABLE P-TYPE WOULD BE SLEET OR FREEZING RAIN. LOOKING AT SOUNDING PROFILES...I WOULD LEAN TOWARDS A FREEZING FOG/DRIZZLE SCENARIO...A GLAZING OF ICE ALONG THE EASTERN SLOPES OF THE BLUE RIDGE BETWEEN 2500-4000 FT.. WE ALSO NEED TO UNDERSTAND THAT THIS IS A DAY 5-6 FORECAST AND MODELS MAY CHANGE OVER THE NEXT SEVERAL DAYS. FOR NOW...WILL KEEP MAJORITY OF PRECIPITATION AS RAIN. WITH CONFIDENCE BEING VERY LOW AT THIS TIME FOR A POSSIBLE TRACE EVENT...WILL NOT ADD TO THE HAZARDOUS WEATHER OUTLOOK (HWO) AT THIS TIME. FOLLOWING P-TYPE CONCERNS TUESDAY NIGHT INTO WEDNESDAY...THE NEXT QUESTION TO ANSWER IS...HOW LONG WILL THE WEDGE REMAIN OVER THE AREA. SURPRISING...THE USUALLY PROGRESSIVE GFS LINGERS A PIECE OF THE WEDGE OVER THE REGION INTO THURSDAY MORNING. DESPITE THE LINGERING WEDGE...12Z GFS STILL HAS THE WINDS TURNING TO THE SOUTH BY WEDNESDAY AFTERNOON. WE WILL CONTINUE TO KEEP THE WEDGE AND CLOUDS IN THE AREA INTO THURSDAY MORNING WITH THE PIEDMONT BEING THE LAST TO CLEAR. THE WEDGE WILL ERODE EACH PERIOD...FROM THE SOUTHWEST TO NORTHEAST AND FROM TOP-DOWN. BY THURSDAY AFTERNOON...A WARM FRONT AND PRESSURE FALLS OVER THE OHIO VALLEY WILL BREAK THE WEDGE. TEMPERATURES COULD POSSIBLY WARM 10F OR SO IN JUST A FEW HOURS. ONCE THE WEDGE BREAKS...WE COULD SEE A DAY OR SO OF WARM TEMPERATURES...THEN A WEAK COLD FRONT WILL BRING LIGHT RAIN SHOWERS TO THE REGION THURSDAY NIGHT AND FRIDAY. THIS FRONT COULD STALL OVER THE REGION FRIDAY.
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&& .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 650 PM EST FRIDAY... LOW CLOUDS HAVE CLEARED WESTERN MOUNTAIN SITES AS W-NW UPSLOPE FLOW HAS ENDED AND WAA PROCESS UNDERWAY. THEREFORE...NOW EXPECTING VFR CONDITIONS THROUGH THE REMAINDER OF THE TAF VALID PERIOD. A NORTHERN STREAM SHORT WAVE WILL SPREAD CONSIDERABLE MID/HIGH CLOUDS ACROSS THE FORECAST AREA OVERNIGHT AND THROUGH THE FIRST HALF OF THE DAY SATURDAY...THEN EXIT TO THE NE OF THE REGION ALLOWING A DECREASE IN THESE CLOUDS BY AFTERNOON. ALL CIGS ASSOCIATED WITH THIS FEATURE WILL BE 080 OR MOST LIKELY HIGHER THROUGH THE TAF VALID PERIOD. VFR VISIBILITIES EXPECTED THROUGHOUT THE TAF VALID PERIOD AS AIR MASS TOO DRY FOR ANY LATE NIGHT/EARLY MORNING FOG DEVELOPMENT. ANY REMAINING NW WINDS WILL DIMINISH AND BECOME MOSTLY CALM OVERNIGHT...BACKING TO THE SSW-SW OVERNIGHT/EARLY SAT...THEN INCREASING TO SUSTAINED SPEEDS OF 6-8KTS WITH LOW END GUSTS BY LATE MORNING ROA/BCB/BLF/DAN IN RESPONSE TO STRENGTHENING WARM ADVECTION PATTERN ON BACK SIDE OF DEPARTING ARCTIC HIGH. HIGH CONFIDENCE IN VFR CIGS/VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. EXTENDED DISCUSSION... VFR CONDITIONS ARE EXPECTED TO LINGER SATURDAY NIGHT AND MUCH OF SUNDAY AHEAD OF A COLD FRONT THAT MAY BRING MVFR CIGS TO AREAS FROM KBCB WESTWARD. THIS COLD FRONT WILL REACH THE REGION MON-TUE WITH A CHANCE OF -SHRA BR AND ASSOCIATED MVFR TO LOCALLY IFR CIGS/VSBYS ALONG THE FRONT. A WEDGE PATTERN EXPECTED TO SET UP BY MON NIGHT/TUE WITH WIDESPREAD MVFR-IFR CIGS AND -RA. SOME -FZRA APPEARS POSSIBLE TUE MORNING THROUGH THE NEW RIVER VALLEY INTO THE SHENANDOAH VALLEY.
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&& .EQUIPMENT... AS OF 1030 AM EST WEDNESDAY... VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WAS MALFUNCTIONING AGAIN. PARTS HAVE BEEN ORDER BUT THE REPAIR MAY NOT BE UNTIL MONDAY. THE VISIBILITY AT KLYH WILL BE AUGMENTED BY STAFF WHEN THE CONTROL TOWER IS OPEN...OTHERWISE THE VISIBILITY WILL BE MISSING. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/MBS NEAR TERM...PC/RAB SHORT TERM...MBS LONG TERM...RCS AVIATION...PC/RAB EQUIPMENT...AMS

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