FXUS61 KRNK 300232
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
932 PM EST SUN NOV 29 2009
.SYNOPSIS...
HIGH PRESSURE WILL BE IN CONTROL TONIGHT...THEN GIVE WAY TO A
COLD FRONT APPROACHING FROM THE WEST EARLY MONDAY...WHICH WILL
PASS THROUGH THE APPALACHIANS AND INTO THE PIEDMONT BY EARLY
AFTERNOON MONDAY. WEDNESDAY AND THURSDAY...A LARGE LOW PRESSURE
SYSTEM WILL MOVE FROM THE LOWER MISSISSIPPI VALLEY ACROSS THE MID
ATLANTIC STATES.
&&
.NEAR TERM /THROUGH MONDAY/...
GETTING SOME LIGH RETURNS ON RADAR THIS EVENING AS MID DECK ROLLS
IN SPITTING OUT SOME SPRINKLES OVER THE NRN CWA. THE CURRENT
FORECAST WILL REMAIN GENERALLY THE SAME...AS THE FRONT LIES ACROSS
THE OHIO VALLEY INTO THE MID MS VALLEY THIS EVENING. REGIONAL
RADAR SHOWING THE MORE CONCENTRATED SHOWER ACTIVITY OVER WRN PA
INTO NRN WV THEN AGAIN ALONG THE FRONT INTO CENTRAL KY AND
ENTERING WRN TN. THE LATEST MODELS CONTINUE TO TIME THE BEST
CHANCE OF SHOWERS ARRIVING THE WRN ZONES TOWARD 12Z. WITH THE
CLOUD COVER AND INCREASING SW WINDS HAVE KEPT THE SIMILAR
REASONING AS THE DAY SHIFT IN SEEING ONLY TEMPS DROPPING INTO THE
40S AT BEST TONIGHT...AND MAYBE EVEN RISING TOWARD 12Z. DEWPOINTS
REMAIN IN 30S...SO THE LIGHT SPRINKLES AND EVAP COOLING SHOULD
ALLOW FOR ANOTHER 6 TO 12 DEGREE DROP.
ON MONDAY THE FRONT MOVES QUICKLY THROUGH THE FORECAST AREA. BUFKIT
AND LOCAL WRF HAVE THE FRONT THROUGH ROANOKE BY 18Z AND THROUGH
DANVILLE AND LYNCHBURG BY 21Z. WILL ADJUST THE TIMING OF THE HIGHEST
PROBABILITY OF RAIN TO LINE UP ALONG AND AHEAD OF THE FRONT.
STILL EXPECTING PRECIPITATION AMOUNTS TO BE LIGHT EAST OF THE BLUE
RIDGE AND LESS THAN ONE QUARTER INCH IN THE MOUNTAINS. 850 MB
TEMPERATURES DROP ABOUT 8 DEGREES DURING THE DAY ON MONDAY. GOING
WITH AN ATYPICAL DIURNAL TREND WITH NEARLY STEADY TEMPERATURES IN
THE WEST.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
BEHIND THE COLD FRONT...UPSLOPE SNOW SHOWERS ARE POSSIBLE
IN FAR WRN SLOPES OF WEST VIRGINIA MONDAY EVENING INTO MONDAY NIGHT
BUT FLOW TURNS FROM NORTHWEST TO WESTERLY PRETTY QUICKLY. ANY
SNOW ACCUMULATION WILL BE VERY LIGHT AND LESS THAN AN INCH. WITH
LIMITED MOISTURE AND POOR TRAJECTORIES....ANY LINGERING SNOW
SHOWERS SHOULD BE FADING AWAY BY 06Z AS FLOW TURNS WESTERLY.
PLAYED LOWS MONDAY NIGHT CLOSE TO ADJMET. SURFACE HIGH PRESSURE
WILL CROSS EAST OVER THE AREA TUESDAY INTO TUESDAY NIGHT. AS SKIES
CLEAR OUT TUESDAY AFTERNOON TEMPERATURES WILL BE HOVERING NEAR
SEASONAL NORMS. WENT CLOSE TO MOSGUIDEBC FOR TEMPERATURES TUESDAY
AND TUESDAY NIGHT.
A LOW PRESSURE SYSTEM DEVELOPS OVER THE GULF OF MEXICO AND SLIDES
NORTHEAST BRINGING OUR NEXT CHANCE FOR PRECIP WEDNESDAY INTO
THURSDAY. LEANED ISC GRIDS FOR THE TIMING OF THE SYSTEM TOWARDS A
ECMWF/SREF/NAM OVER THE FASTER GFS.
DECENT OVERRUNNING RAIN WILL SPREAD ACROSS THE COUNTY WARNING AREA
WEDNESDAY BEGINNING IN THE SOUTHWEST AND PUSHING NORTH NORTHEAST.
RAIN COULD BE HEAVY AT TIMES WITH MOIST WARM AIR ADVECTING OVER THE
REGION AND AN INCREASING LOW LEVEL JET. RAINFALL AMOUNTS OF A HALF
OF AN INCH TO AN INCH POSSIBLE WEDNESDAY INTO THURSDAY MORNING.
HIGHER AMOUNTS OF AN INCH OR TWO ARE POSSIBLE ALONG EASTERN SLOPES
OF THE BLUE RIDGE.
MODELS PROG A LOW LEVEL JET INCREASING TO 40 TO 50 KNOTS EAST OF THE
BLUE RIDGE MOUNTAINS CONCENTRATED IN THE PIEDMONT AREAS OF VIRGINIA
AND NORTH CAROLINA. WILL HAVE TO MONITOR THE SITUATION TO SEE HOW
THE WINDS PLAY OUT TO SEE IF THEY WILL REACH ANY ADVISORY CRITERIA.
WEDNESDAY WILL BE DAMP AND COLD. LEANED HIGHS TOWARDS THE COLDER
MOSGUIDEBC VALUES FOR WEDNESDAY. MAX TEMPERATURES WILL BE IN THE 40S
IN THE MOUNTAINS TO LOWER 50S IN THE PIEDMONT AREAS WEDNESDAY.
EXPECTING THE COLD AIR TO ADVECT IN LATE WEDNESDAY NIGHT BUT IF THE
FRONT MOVES EVEN SLOWER...THEN THE COLDER AIR WILL NOT GET INTO THE
AREA UNTIL THURSDAY NIGHT OR LATER. FOLLOWED HPCGUIDE FOR LOW
WEDNESDAY NIGHT.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
SYSTEM WILL BE EXITING THE REGION AND MOVING OVER NEW ENGLAND ON
THURSDAY. QUESTIONS REMAIN ON HOW FAST RAIN EXITS THE EAST WITH THE
DISTURBANCE AND RAIN/SNOW SHOWERS ENTER THE WEST WITH THE COLD
FRONTAL BOUNDARY. GFS IS THE FASTEST OF THE MODELS WITH RAIN EXITING
THE AREA AROUND SUNRISE THURSDAY MORNING AND THE COLD FRONT MOVING
THROUGH THE AREA EARLY IN THE AFTERNOON. HPC...RNK AND OTHER OFFICES
FAVORING THE SLOWER NAM/ECMWF. WILL CONTINUE TO KEEP HIGH POPS IN
THE NORTHEAST WITH CHANCE EVERY WHERE ELSE. BY EARLY
AFTERNOON...RAIN EXITS AND LOW CHANCE POPS FOR SHOWERS COMES INTO
PLAY IN WESTERN GREENBRIER COUNTY. OVERNIGHT THURSDAY AND INTO
FRIDAY NIGHT...TYPICAL WESTERN UPSLOPE SNOW SHOWERS WILL FALL WITH
FLURRIES AS FAR AS THE BLUE RIDGE. LIGHT ACCUMULATIONS ARE POSSIBLE
ON WESTERN SLOPES...ESPECIALLY ABOVE 3000 FEET DURING THE OVERNIGHT
HOURS THURSDAY AND FRIDAY NIGHT. DURING THE DAY
FRIDAY...TEMPERATURES COULD EDGE ABOVE FREEZING AND SUNSHINE POKING
THROUGH THE CLOUDS FROM TIME TO TIME...COULD MELT/LIMIT SNOW
ACCUMULATIONS. PRIMARILY A WEST WIND WITH NO GREAT LAKE CONNECTIONS
AND DAY TIME MELTING...NOT FORESEEING HIGHLIGHTING IN HWO AT THIS
TIME. EVEN THOUGH SURFACE TEMPERATURES WILL GET ABOVE FREEZING IN
MOST MOUNTAINS LOCATIONS...WARM BOUNDARY WILL BE SHALLOW AND SNOW
SHOWERS/FLURRIES WILL CONTINUE THROUGH THE DAY FRIDAY. THE WINDS
WILL BE BREEZY AND GUSTY IN THE WAKE OF THE FRONT BUT NOT SEEING ANY
CRITERIA BEING MET AT THIS TIME. THESE WESTERLY WINDS WILL DOWNSLOPE
IN THE EAST AND ADD A FEW DEGREES TO THE TEMPERATURE.
HOWEVER...TEMPERATURES WILL BE BELOW NORMAL AND FEEL CHILLY WITH THE
WIND BLOWING.
MOUNTAIN SNOW SHOWERS WILL COME TO AN END FRIDAY NIGHT AS HIGH
PRESSURE BUILDS INTO THE REGION. OVER THE WEEKEND...A WARM FRONT
WILL BRING MODERATING TEMPERATURES TO THE AREA BUT STILL REMAIN
BELOW NORMAL. HIGH PRESSURE WILL REMAIN IN THE REGION THROUGH EARLY
NEXT WEEK.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
FOLLOWING THE 18Z NAM SHOWS VFR CONDITIONS OVERNIGHT WITH LOWERING
CIGS. POTENTIAL IS THERE FOR SOME LLWS ESPECIALLY AT LWB AROUND
04-06Z AS 40 KNOT 8H JET MOVES ACROSS. HOWEVER...IT SEEMS
BORDERLINE AT THIS POINT.
AS THE SHOWERS MOVE INTO TOWARD 12Z INTO BLF/LWB CIGS WILL DROP TO
MVFR. DURING THE DAY THE SHOWERS WILL ADVANCE EAST TO THE OTHER
SITES WITH MVFR CIGS EXPECTED. POTENTIAL FOR IFR CIGS ALSO EXISTS
AT BLF AND HIGHER TERRAIN AIRPORTS SUCH AS HSP AS THE SHOWERS
WEAKEN BEHIND THE FRONT. LEFT IFR OUT FOR NOW...AS IT WILL BE MORE
ON THE END OF THIS TAF PERIOD. WINDS WILL START OUT FROM THE SW
THEN VEER WEST TO NW BEHIND THE FRONT FROM 15Z AT BLF/LWB TO MID
AFTN AT ROA AND LATER AT DAN/LYH.
AS COLDER AIR SURGES IN...A BRIEF SNOW SHWR IS POSSIBLE BEHIND
THE FRONT MONDAY EVENING AT BLF AND LWB...WITH SOME MVFR CEILINGS
ON MONDAY NIGHT.
CONDITIONS WILL RETURN TO VFR ON TUESDAY AS THE LOW LEVEL
MOISTURE EXITS THE REGION AND HIGH PRESSURE BUILDS BACK IN FROM
THE WEST.
ANOTHER STORM SYSTEM WILL BRING A GOOD CHANCE FOR SIGNIFICANT RAIN
BY WEDNESDAY MORNING...WITH A MUCH BETTER CHANCE FOR WIDESPREAD
IFR CONDITIONS...POSSIBLY CONTINUING THROUGH THURSDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/SK
NEAR TERM...AMS/WP
SHORT TERM...KK
LONG TERM...RCS
AVIATION...AMS/WP
