FXUS61 KRNK 022019
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
319 PM EST WED DEC 2 2009
.SYNOPSIS...
LOW PRESSURE OVER THE TENNESSEE VALLEY WILL MOVE QUICKLY INTO THE
OHIO VALLEY BY THURSDAY MORNING THEN ACROSS NEW ENGLAND BY
THURSDAY NIGHT. THIS SYSTEM WILL PUSH A COLD FRONT THROUGH THE
REGION TONIGHT FOLLOWED BY HIGH PRESSURE ON FRIDAY. ANOTHER AREA
OF LOW PRESSURE MAY DEVELOP ALONG THE SOUTHEAST COAST AND MOVE
OFFSHORE THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS 850 MB WARM FRONT MOVES THROUGH THIS AFTERNOON...WINDS STAY
STRONG BUT WEER TO THE SOUTH THAN SOUTHWEST...WHICH WILL END THE
UPSLOPE ENHANCEMENT OF RAINFALL ALONG THE EASTERN BLUE RIDGE. NO
CHANGES TO THE HIGH WIND WARNING OR ADVISORY AT THIS TIME.
LARGE AREA OF RAINFALL OVER SOUTH CAROLINA AND GEORGIA LINES UP
WELL WITH THE UPPER DIFFULENT REGION AHEAD OF THE JET STREAK. STILL A
TREMENDOUS AMOUNT OF ISENTROPIC LIFT AND UPPER DIFFLUENCE THROUGH
00Z TONIGHT. THEN DRY SLOT AND COLD FRONT CROSS THE FORECAST AREA
DURING THE EVENING. MODELS ALREADY SEEM SLOW COMPARED TO WHERE
THIS PRECIP WAS AT 18Z. WILL LEAN TOWARD THE FASTER GFS BUT SPEED
UP ITS TIMING FOR TONIGHT. EXPECT A NON-DIURNAL TEMPERATURE TREND
WITH THE TEMPERATURE RISING AFTER THE WARM FRONT GOES THROUGH THEN
FALLING LATE TONIGHT BEHIND THE COLD FRONT.
LOW LEVEL MOISTURE REMAINS BELOW 700 MB. ANY CLEARING EAST
OF THE BLUE RIDGE WILL BE AFTER THE FRONT GOES THROUGH. WILL
KEEP ISOLATED THUNDER IN THE FORECAST FOR TONIGHT WITH THE
SOUTHEAST COUNTIES IN THE WARM SECTOR WHERE THE LOCAL WRF HAD
BELOW ZERO LIFTED INDEX VALUES.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
THE LOW PRESSURE SYSTEM MOVES NORTHEAST AWAY FROM THE FORECAST AREA
THURSDAY LEAVING BEHIND A WEST NORTHWEST FLOW. UPSLOPE RAIN/SNOW
SHOWERS WILL CONTINUE IN THE USUAL WESTERN UPSLOPE AREAS OF
SOUTHEAST WEST VIRGINIA...PORTIONS OF SOUTHWEST VIRGINIA AND SOUTH
INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA IN THE MORNING HOURS
BEFORE TAPERING OFF IN THE EARLY AFTERNOON. BUFKIT SOUNDINGS
INDICATE A SUBSIDENCE INVERSION WITH SHALLOW LOW LEVEL MOISTURE
REMAINING FOR THURSDAY.
AS FOR WINDS...THEY WILL DECREASE THROUGHOUT THE DAY THURSDAY AS THE
GRADIENT RELAXES WITH WEAK RIDGING ENTERING THE AREA FROM THE WEST.
HIGH PRESSURE GETS PUSHED NORTH OF THE COUNTY WARNING AREA AS A LOW
PRESSURE SYSTEM DEVELOPS OFF THE SOUTH CAROLINA COAST FRIDAY INTO
FRIDAY NIGHT. DRY WEATHER IS EXPECTED FOR FRIDAY AFTERNOON INTO FRIDAY
NIGHT BEFORE THE INFLUENCE OF THE LOW IMPACTS THE AREA WHILE PUSHING
NORTHEASTWARD ALONG THE EAST COAST.
ONLY MINOR DIFFERENCES DETECTED BETWEEN THE LATEST 12Z RUN OF THE
MODELS. THE NAM SEEMS TO BE SLIGHTLY DEEPER WITH THE LOW AND A
LITTLE SLOWER THAN THE GFS AND ECMWF.
WINDS WILL BE GENERALLY OUT OF THE NORTH AS 850MB TEMPS RANGE FROM
-3C IN THE SOUTHEAST TO -8C IN THE NORTHWEST. PRECIP WILL BE
INCREASING FROM SOUTHWEST TO NORTHEAST SATURDAY MORNING. DEPENDING
ON THE TIMING OF THIS SYSTEM...BELIEVE THE TEMPERATURES AT THE
SURFACE AND ALOFT WILL BE JUST COLD ENOUGH FOR THE PRECIP TO BEGIN
AS ALL SNOW...ESPECIALLY IN THE HIGHER ELEVATIONS IN THE WEST. THEN
A MIX OF RAIN AND SNOW IS EXPECTED THROUGH THE DAY ON SATURDAY ALONG
AND WEST OF THE BLUE RIDGE. HOWEVER...A FEW LIGHT SNOW SHOWERS COULD
MAKE IT TO THE PIEDMONT AREAS OVERNIGHT SATURDAY AS TEMPERATURES
WILL FALL INTO THE MID 20S.
TEMPERATURES WILL BE DROPPING FROM NEAR TO BELOW NORMAL EACH DAY
THROUGH SATURDAY NIGHT DUE TO THE COLD AIR ADVECTION FILTERING INTO
THE AREA. THUS FAR...SATURDAY LOOKS TO BE THE COLDEST DAY WE HAVE
HAD SO FAR WITH HIGHS STRUGGLING TO REACH 40 DEGREES.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
LEANED MEDIUM RANGE TOWARDS HPCGUIDE WHICH WAS A BLEND OF ECMWF AND
GFS ENSEMBLES. QUASI ZONAL FLOW EXPECTED WITH SOME AMPLIFICATION OF
THE PATTERN ON TUESDAY INTO WEDNESDAY. ON SUNDAY AND MONDAY...THE
UPPER LEVEL TROUGH WILL PUSH EAST INTO THE ATLANTIC OCEAN AS HIGH
PRESSURE/RIDGE ALOFT BUILDS EAST ACROSS OUR AREA. FRONTAL BOUNDARY
APPROACHES FROM THE WEST MONDAY NIGHT INTO TUESDAY. AS THE LOW
PRESSURE CENTER AND FRONT SPREAD EAST THE CHANCES OF PCPN INCREASE
BY MIDWEEK.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
CONDITIONS WILL CHANGES QUICKLY DURING THROUGH 06Z. MODELS ALREADY
SEEMS SLOW WITH THE TIMING IF THE BEST LIFT GENERATED BY THE UPPER
LOW AND ASSOCIATED JET STREAK. WENT WITH TIMING THAT WAS SLIGHTLY
FASTER THAN THE FAST GFS. THIS BRINGS A WARM FRONT NORTH THROUGH
THE FORECAST AREA THIS AFTERNOON AND A COLD FRONT EAST ACROSS THE
AREA BY 06Z.
UNTIL THE WARM FRONT GOES THROUGH THERE WILL BE WIDESPREAD IFR TO
LIFR CEILINGS WITH LIGHT TO MODERATE RAIN. CEILINGS WILL LIFT TO
MVFR ONCE THE WARM FRONT PASSES. ROA...LYH...AND DAN WILL IMPROVE
TO VFR BEHIND THE COLD FRONT AS THE DRY SLOT MOVES INTO THE AREA.
BLF AND LWB WILL REMAIN IN MVFR CLOUDS THROUGH THE END OF THE
FORECAST PERIOD.
THERE IS A VERY STRONG LOW LEVEL JET THAT WILL BECOME SOUTHEAST
THEN SOUTHWEST AS THE LOW MOVES INTO NEW YORK. HAVE MAINTAINED LOW
LEVEL WIND SHEAR AT ALL OF THE TAF SITES. WIND SPEEDS ABOVE THE
INDICATED LEVEL MAY BE EVEN STRONGER THAN IN THE FORECAST.
UPSLOPE SNOW SHOWERS TO LINGER MVFR CONDITIONS ACROSS SE WVA INTO
FRIDAY WITH VFR ELSEWHERE. ANOTHER STORM SYSTEM COULD BRING LOWER
CIGS AND POSSIBLY A LITTLE MORE WINTRY PRECIP FOR FRIDAY NIGHT AND
SATURDAY FOLLOWED BY VFR UNDER HIGH PRESSURE FOR SUNDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR VAZ011-013-014-
016>020-022>024-032>035.
HIGH WIND WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ007-009-
010-012-015.
NC...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ001>003-018-
019.
WV...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR WVZ043>045.
HIGH WIND WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ042.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...REB
LONG TERM...KK
AVIATION...AMS/JH
