Issued by NWS Blacksburg, VA
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS61 KRNK 230139 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 839 PM EST SUN NOV 22 2009 .SYNOPSIS...-- Changed Discussion --LOW PRESSURE WILL LIFT NORTHEAST OUT OF THE GULF COAST STATES AND MOVE OFF THE MID ATLANTIC COAST BY MONDAY NIGHT AS A WEDGE OF COOL HIGH PRESSURE REMAINS ANCHORED FROM NEW ENGLAND SOUTHWEST INTO THE MID APPALACHIANS. THESE SYSTEMS WILL RESULT IN ABUNDANT CLOUD COVER AND COOL TEMPERATURES FOR THE NEXT COUPLE OF DAYS...ALONG WITH RAIN OR DRIZZLE TONIGHT INTO MONDAY.-- End Changed Discussion --&& .NEAR TERM /UNTIL 8 AM MONDAY MORNING/...-- Changed Discussion --SHORT WAVE CONTINUED TO MOVE NORTHEAST AND WAS ENTERING SOUTHEAST KENTUCKY AT 01Z. A BROAD BAND OF RAIN ASSOCIATED WITH THE BEST SYNOPTIC SCALE LIFT AND STRONGEST ISENTROPIC LIFT WAD JUST ADVANCING INTO THE SOUTHWEST COUNTIES OF THE FORECAST AREA AT 00Z. THE RUC...HRRR...LOCAL WRF...AND SREF ALL HAVE RAINFALL BECOMING WIDESPREAD ACROSS THE SOUTHERN COUNTY WARNING AREA BETWEEN 03-06Z. HAVE ADJUSTED THE TIMING OF THE HIGHEST PROBABILITY OF RAIN TO ACCOUNT FOR RAINFALL CURRENTLY APPROACH SOUTHERN VIRGINIA AND THE LATEST TIMING OF THE MODELS. THERE IS STILL SOME ROOM FOR EVAPORATIVE COOLING IN THE NORTHERN COUNTY WARNING AREA WITH SURFACE DEWPOINTS IN THE UPPER 30S TO LOWER 40S. HIGHEST ELEVATIONS MAY STILL DROP INTO THE MID TO UPPER 30S BEFORE RISING A COUPLE OF DEGREES AS THE CLOUDS LOWER AND RAIN BEGINS. 00Z SOUNDINGS AT GSO AND RNK SHOW DEEPER EAST TO SOUTHEAST UPSLOPE WINDS BELOW 700 MB AND A SATURATED AIRMASS AT MID AND HIGH LEVELS. PRECIPITABLE WATER AT THE BCB PROFILER HAS BEEN RISING SHARPLY SINCE LATE THIS AFTERNOON AND WAS GREATER THAN 0.5 INCHES AT 01Z. WITH THE SOUTHERN COUNTY WARNING AREA CLOUDY AND WITH CONTINUED MOISTENING OF THE LOW LEVELS...EXPECT NEARLY STEADY TEMPERATURES OVERNIGHT.-- End Changed Discussion --&& .SHORT TERM /8 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/... MAIN SHORT WAVE AND ASSOCIATED WEAK UPPER LEVEL TROUGH WILL MOVE NORTH OF THE REGION AND OFF THE NEW ENGLAND COAST MONDAY NIGHT. OVER THE IMMEDIATE AREA...A SURFACE WEDGE WILL REMAIN WITH THE FLOW OUT OF THE NORTH-NORTHEAST. WITH THE PARENT SYSTEM AND MOISTURE TO THE NORTH...THE NORTHERLY FETCH WILL CONTINUE TO KEEP THE LOW LEVELS SATURATED. ALSO AIDING IN THE NORTHERLY FETCH WILL BE A WEAK SURFACE REFLECTION OFF THE OUTER BANKS OF NORTH CAROLINA. MOSTLY CLOUDY SKIES WILL STAY OVER THE REGION THROUGH TUESDAY MORNING WITH LOW CHANCE LIGHT RAIN POSSIBLE ACROSS THE NORTHEASTERN PORTIONS OF THE CWA AND MAINLY DRIZZLE ALONG THE BLUE RIDGE...PARTICULARLY NORTHEASTERN SLOPES. DURING THE DAY TUESDAY...PARENT SYSTEM PULLS FAR ENOUGH TO THE NORTH WITH POSSIBLE SUNSHINE POKING THROUGH THE CLOUDS ACROSS SOUTHEASTERN WEST VIRGINIA. TIME-HEIGHT CROSS SECTIONS KEEPING RESIDUAL MOISTURE IN THE LOW LEVEL ALONG AND EAST OF THE BLUE RIDGE THROUGH TUESDAY NIGHT TO HAVE AFTERNOON TEMPERATURES AROUND NORMAL AND OVERNIGHT LOWS WELL ABOVE NORMAL FOR THE EASTERN TWO-THIRDS OF THE CWA. DO NOT THINK RAINFALL...IF ANY...WILL MEASURE BUT THERE COULD BE AREAS OF DRIZZLE ALONG THE EASTERN SLOPES INTO TUESDAY AFTERNOON. FOR NOW...WILL KEEP ANY PRECIPITATION IN THE MORNING. ALSO CHARACTERIZE DRIZZLE SIMILAR TO RAIN...CHANCE/SLIGHT CHANCE...TO KEEP TEXT PRODUCTS SIMPLE. DOES LOOK LIKE DRIZZLE WILL BE THE DOMINATE P-TYPE MONDAY NIGHT INTO TUESDAY MORNING. AS TYPICAL WITH ANY SATURATED WEDGE...ANY BREAKS IN THE CLOUDS TUESDAY AFTERNOON WILL FILL BACK IN TUESDAY NIGHT. WINDS WILL BE LIGHT AND VARIABLE AND COULD TURN OUT OF THE SOUTHEAST EARLY WEDNESDAY MORNING AS THE NEXT SYSTEM ENTERS THE MID WEST. LOW CLOUDS AND FOG LIKELY WITH PATCHY DRIZZLE ON EASTERN SLOPES POSSIBLY THROUGH WEDNESDAY MORNING. PRE FRONTAL TROUGH TO APPROACH THE AREA WEDNESDAY WITH THE WEDGE BREAKING BY THE AFTERNOON. WILL CONTINUE TO HOLD CLOUDS ALONG THE FOOTHILLS AND SOUTHERN PIEDMONT OF VIRGINIA INTO WEDNESDAY MORNING AS MODELS TEND TO ERODE WEDGE TO QUICK. AS THE WEDGE BREAKS WEDNESDAY...TEMPERATURES SHOULD SOAR BACK TO AND/OR ABOVE NORMAL...ESPECIALLY WITH A WARM START. THE AREA WILL LIKELY REMAIN IN THE WARM SECTOR AND POSSIBLY PRECIPITATION-FREE WEDNESDAY NIGHT TO KEEP TEMPERATURES ABOVE NORMAL. && .LONG TERM /THURSDAY THROUGH SUNDAY/... OUR WEATHER PATTERN FOR THE UPCOMING THANKSGIVING HOLIDAY AND HOLIDAY WEEKEND WILL BE DOMINATED BY A SLOW MOVING UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ASSOCIATED FRONTAL BOUNDARIES. GUIDANCE IS IN SOMEWHAT GOOD AGREEMENT OF BRINGING LOW PRESSURE EASTWARD THROUGH THE GREAT LAKES REGION ON THANKSGIVING DAY. THIS LOW IN TURN IS PROGGED TO HELP PROMOTE CYCLOGENESIS OFF THE NEW ENGLAND COAST BY FRIDAY. THEN THE PHASED LOW PRESSURE SYSTEMS WILL TRACK NORTHEAST TOWARDS NEWFOUNDLAND BY SATURDAY...WITH A HEALTHY NORTHWEST FLOW KICKING IN OVER OUR REGION FRIDAY INTO SATURDAY. HIGH PRESSURE IS EXPECTED TO ARRIVE ON SATURDAY NIGHT. WHAT THIS MEANS FOR OUR WEATHER IS A THANKSGIVING WITH SCATTERED RAIN SHOWERS ACROSS THE AREA...WITH PERHAPS A LITTLE SNOW MIXED IN EARLY IN THE MORNING IN THE HIGHER ELEVATIONS OF NORTHWEST NORTH CAROLINA AND SOUTHEAST WEST VIRGINIA. THE PRECIPITATION WILL BE ASSOCIATED WITH THE PASSAGE OF A COLD FRONT. HEADING INTO THURSDAY NIGHT AND FRIDAY...NOTABLY COLDER AIR WILL RACE INTO THE AREA ON INCREASING NORTHWEST WINDS. GUSTS OF 30 TO 35 MPH WILL BE POSSIBLE AT THE HIGHER ELEVATIONS...WITH SCATTERED SNOW SHOWERS SPREADING AS FAR EAST AS THE CREST OF THE BLUE RIDGE LATE THURSDAY NIGHT. MEASURABLE SNOW WILL BE POSSIBLE IN THE PREFERRED UPSLOPE SNOW REGIONS OF SOUTHEAST WEST VIRGINIA. ON FRIDAY...COVERAGE OF PRECIPITATION WILL BE ABOUT THE SAME...BUT WITH WARMING TEMPERATURES THE PRECIPITATION SHOULD TRANSITION BACK TO SCATTERED SHOWERS...WITH A TREND TOWARDS DECREASING COVERAGE LATE. ON FRIDAY NIGHT...EVEN COLDER TEMPERATURES ARE EXPECTED WITH SIMILAR...OR EVEN SLIGHTLY STRONGER WIND GUSTS...BUT PRECIPITATION COVERAGE WILL BE LESS. ISOLATED SNOW SHOWERS WILL BE POSSIBLE...PRIMARILY OVER SOUTHEAST WEST VIRGINIA...NEIGHBORING PARTS OF SOUTHWEST VIRGINIA...AND IN THE MOUNTAINS OF NORTHWEST NORTH CAROLINA. ON SATURDAY INTO SATURDAY NIGHT...THE PRESSURE GRADIENT WILL BEGIN TO WEAKEN SO LOOK FOR SLOWER WIND SPEEDS AND GUSTS AS COMPARED TO THURSDAY NIGHT THROUGH FRIDAY NIGHT. ALSO...EVEN LESS MOISTURE WILL RESULT IN ONLY ISOLATED RAIN/SNOW SHOWERS IN THE MOUNTAINS. BY SATURDAY NIGHT...WE ARE EXPECTING A DRY FORECAST WITH THE COLDEST NIGHT OF THE WEEKEND. MID TO UPPER 20S WILL BE COMMON IN THE MOUNTAINS...WITH MOST AREAS EAST OF THE BLUE RIDGE AROUND 30 OR IN THE LOWER 30S. ON SUNDAY...WINDS TAKE ON A BIT MORE OF A SOUTHWEST COMPONENT AHEAD OF OUR NEXT APPROACHING COLD FRONT. THERE IS A SLIGHT CHANCE OF SOME SHOWERS IN THE SOUTHEAST WEST VIRGINIA MOUNTAINS IN ASSOCIATION WITH THIS APPROACHING FRONT ON SUNDAY. && .AVIATION /02Z MONDAY THROUGH FRIDAY/...-- Changed Discussion --MOISTURE ALOFT IS BEGINNING TO OVERRUN THE REGION...BUT MOST OF IT IS STILL BE BEING USED TO MOISTEN THE COLUMN. AS THE NIGHT PROGRESSES...EXPECT TO SEE A TREND TOWARDS LOWERING CEILINGS AND VISIBILITIES TO MVFR WITH LIGHT RAIN. MOST OF THE SOUTHERN HALF OF THE AREA IS EXPECTED TO EXPERIENCE THIS BY 06Z. THE REST OF THE AREA SHOULD EXPERIENCE THIS BY 09Z...WITH A GENERAL TREND THROUGH MORNING OF CONDITIONS WORSENING TO IFR. IFR CIGS LIGHT RAIN ARE EXPECTED TO CONTINUE THROUGH MUCH OF THE DAY MONDAY...WITH VSBYS EXPECTED TO IMPROVE TO MVFR OR LOW END VFR BY THE AFTERNOON. COOL WEDGE WILL LIKELY PERSIST THROUGH MONDAY NIGHT...AND PERHAPS INTO TUESDAY NIGHT BEFORE NEXT APPROACHING SHORT WAVE FROM THE WEST ALLOWS SURFACE WINDS TO VEER AROUND INTO THE SOUTHWEST...GRADUALLY ERODING AND DISPLACING TENACIOUS MOIST COOL. EXPECT TO SEE GENERAL IFR CONDITIONS TO PERSIST THROUGH MUCH OF THE PERIOD...WITH MANY OF THE MOUNTAIN RIDGES REMAINING IN LIFR CONDITIONS. SOME BRIEF RISING OF CEILING INTO MVFR RANGE IS POSSIBLE IN VICINITY OF BLUEFIELD ON MONDAY AND TUESDAY FROM LATE MORNING INTO THE AFTERNOON HOURS DUE TO LOCALIZED DOWNSLOPING UNDER A SOUTHEASTERLY WIND...BUT THIS NOT AT ALL CERTAIN AT THIS POINT AND MAY BE THE ONLY AREA TO EXPERIENCE ANY MVFR CONDITION THE NEXT COUPLE OF DAYS. AS INDICATED ABOVE...SHOULD SEE UNIVERSAL IMPROVEMENT OF FLIGHT CONDITIONS BACK INTO VFR OR UNRESTRICTED RANGE BY WEDNESDAY INTO THURSDAY...BUT ARRIVAL OF STRONG COLD FRONT THURSDAY INTO FRIDAY WILL LIKELY BRING A RETURN TO MVFR CONDITIONS IN UPSLOPE AREAS WEST OF THE BLUE RIDGE...ALONG WITH AN INCREASING THREAT OF SOME MOUNTAIN RAIN OR SNOW SHOWERS. DOWNSLOPING CONDITIONS EAST OF THE BLUE RIDGE SHOULD HELP TO KEEP THOSE AREAS MAINLY IN VFR RANGE DURING THE LATE WEEK PERIOD.-- End Changed Discussion --&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WERT NEAR TERM...AMS SHORT TERM...RCS/WERT LONG TERM...DS AVIATION...DS/WERT
