FXUS61 KRLX 271047
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
543 AM EST FRI NOV 27 2009
.SYNOPSIS...
COLD NORTHWEST FLOW BRINGS RAIN AND SNOW SHOWERS...WITH ACCUMULATING
SNOW IN THE MOUNTAINS THROUGH TONIGHT. HIGH PRESSURE RETURNS FOR
THIS WEEKEND. COLD FRONT WITH RAIN MONDAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS THE VORTICITY MAX EXIT NORTHEAST...THE SNOW AND RAIN SHOWERS WILL
DIMINISH ACROSS THE LOWLANDS BY NOON TIME. HOWEVER...LEFT OVER LOW
LEVEL MOISTURE AND DEEP NORTHWEST FLOW WILL CONTINUE TO PRODUCE
UPSLOPE SNOW ACROSS THE HIGHER ELEVATIONS...ESPECIALLY THE NORTHEAST
MOUNTAINS THROUGH TONIGHT. THE MOST WIDESPREAD PRECIP SHOULD OCCURS
DURING THE MORNING HOURS. WITH WIND GUSTS FROM 20 TO 30 KNOTS...
BLOWING SNOW WILL BE POSSIBLE AT THE HIGHEST ELEVATIONS LATER THIS
AFTERNOON.
THE WARM GROUND AND MARGINAL LOW LEVEL TEMPS MEAN VIRTUALLY NO
ACCUMULATION IN THE LOWLANDS. PREVIOUS POPS/WX AND SNOW
ACCUMULATIONS LOOK GOOD NEEDING NO CHANGES. THEREFORE...KEPT 3-6
INCHES ABOVE 3000 FEET FOR THE 24 PERIOD THROUGH 00Z SATURDAY...WITH
1-3 INCHES IN OTHER AREAS FROM EKN TO BKW. BELIEVE NO NEED OF WINTER
WEATHER ADVISORY ATTM AS ACCUMULATIONS WILL OCCUR ABOVE 3KFT AND
WILL NOT MET THE COUNTY AVERAGE CRITERIA.
WENT MAINLY WITH A BLEND OF BIAS CORRECTED SREF AND GMOS FOR
TEMPERATURES THROUGH THE PERIOD. MODELS BRING THE COLDEST H8
TEMPERATURES AROUND 15Z WITH THE THERMAL TROUGH...BRINGING A NON
DIURNAL TREND OR ALMOST STEADY TEMPERATURES TODAY. SKIES EXPECTED TO
CLEAR ACROSS MOST SITES TONIGHT...ALLOWING FOR GOOD RADIATIONAL
COOLING AND ASSOCIATED DROP IN TEMPERATURES GENERALLY IN THE UPPER
TO MID 20S TONIGHT.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS THE NORTHWEST FLOW WINDS DOWN...A DRY ATMOSPHERE TAKES OVER WITH
BROAD SCALE UPPER LEVEL HIGH PRESSURE. SURFACE HIGH PRESSURE WILL
CONTROL MORE OF THE SOUTHEASTERN CONUS AND ALLOW THE CWA TO BE
AFFECTED BY THE NEXT INCOMING FRONTAL SYSTEM. UNTIL THIS
POINT...HIGH LEVEL CLOUDS BEGIN TO INCREASE AS THE UPPER LEVEL FLOW
BEGINS TO TURN MORE SOUTHWESTERLY WITH THE RIDGE NOW DOWNSTREAM.
COLD FRONT WILL BE A LATE SUNDAY NIGHT AND MONDAY FEATURE...AND
LOOKS TO BE BOTH WELL ORGANIZED AND STRONG ENOUGH TO PASS THROUGH
THE MOUNTAINS TO THE EAST. COLD AIR ADVECTION BRINGS MILD WEATHER
BACK DOWN BELOW NORMAL BEHIND THE FRONT INTO WEDNESDAY AS HIGH
PRESSURE INFLUENCES MAKE A COMEBACK.
SATURDAY NIGHT LOOKS LIKE A SCENARIO FOR EFFICIENT RADIATIONAL
COOLING...ESPECIALLY IN THE SHELTERED VALLEYS WITHIN THE HIGHER
ELEVATIONS. THIS WILL BE OFFSET A BIT LATER WITH CIRRUS ADVECTION.
TIMING WILL BE CRUCIAL HERE IN DETERMINING JUST HOW FAR DOWN TO TAKE
LOCATIONS LIKE ELKINS.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
ALL THE MODELS HAVE NORTHERN STREAM FLOW DOMINATING EARLY NEXT WEEK.
PER HPC...WE ARE FOLLOWING THE OPERATIONAL ECMWF FOR DETAILS AS
OTHER MODELS...ALONG WITH MUCH OF THEIR ENSEMBLES...HAVE TRENDED
TOWARD THIS MOST CONSISTENT ECMWF...WHICH SHOWED THIS SCENARIO
FIRST.
THIS ACCEPTED SCENARIO HAS A COLD FRONT IN THIS NORTHERN STREAM
MOVING STEADILY ACROSS THE OHIO VALLEY ON MONDAY...EXITING THE
MOUNTAINS BY MONDAY NIGHT. MODELS SHOWING A GOOD SLUG OF MOISTURE
AND MILD AIR AHEAD OF THIS FRONT...BUT INSTABILITY REMAINS ALMOST
NIL. THUS...EXPECT A GOOD SLUG OF RAIN MONDAY...WHICH BEING ON THE
LAST DAY OF NOVEMBER WILL LIKELY ERASE OUR POTENTIAL DRIEST NOVEMBER
ON RECORD. WITH MUCH OF THE RAIN BEING POST FRONTAL...HAVE CONTINUED
POPS MONDAY NIGHT...AND INTO TUESDAY MORNING IN THE MOUNTAINS. LOOKS
LIKE ENOUGH COLD AIR ALOFT COMES IN FOR SOME CHANGEOVER TO SNOW
SHOWERS IN THE HIGHER ELEVATIONS OF THE NORTHERN WEST VIRGINA
MOUNTAINS LATER MONDAY NIGHT AND EARLY TUESDAY...WITH LITTLE
ACCUMULATION. THEN...LOOK FOR A BREAK WITH HIGH PRESSURE BUILDING
ACROSS ON TUESDAY AND TUESDAY NIGHT.
MEANWHILE...WHILE THE NORTHERN STREAM HAS MOVED RIGHT ALONG...
SOUTHERN ENERGY IN THE FORM OF A CLOSED UPPER LOW HANGS BACK OVER
THE SOUTHERN PLAINS EARLY NEXT WEEK. THIS SOUTHERN SYSTEM IS THEN
PROGGED TO LIFT NORTHEASTWARD TOWARD THE OHIO VALLEY WEDNESDAY AND
THURSDAY...AS A NEW POWERFUL NORTHERN STREAM SYSTEM DIVES INTO THE
PLAINS STATES. THIS WILL BRING ANOTHER SURGE OF MILD AIR AND A GOOD
SLUG OF MOISTURE FOR RAIN DURING WEDNESDAY INTO THURSDAY TO OUR AREA.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
RADAR IMAGES CONTINUE TO SHOW LIGHT RAIN/SNOW MIX ACROSS THE
LOWLANDS...AND SNOW SHOWERS ACROSS THE EASTERN MOUNTAINS WHERE
TEMPERATURES ARE BELOW 32F. IFR VISIBILITIES WILL BE AROUND 2 MILES
AND CEILINGS AROUND 900 FEET UNDER LIGHT SNOW SHOWERS. OUTSIDE
SHOWERS...CEILINGS CAN BE AROUND 1200 FEET THIS MORNING. EXPECT
CONDITIONS TO IMPROVE TO VFR AT MOST SITES AS CLEARING SPREADS FROM
SOUTH TO NORTH THIS AFTERNOON WHILE THE UPPER LEVEL SYSTEM EXITS
NORTHEAST.
GUSTY WINDS WILL CONTINUE ACROSS MOST SITES EXCEPT FOR THOSE
PROTECTED BY MOUNTAINS LIKE EKN. BUT EVEN EKN WILL BE GUSTY UNDER
SNOW SHOWERS DURING THE MORNING HOURS. FLOW SHIFTS WNW AND REMAIN
SOMEWHAT GUSTY MOST OF THE DAY.
AFTER 12Z SATURDAY...
NO SIGNIFICANT IFR CONDITIONS ARE EXPECTED AT THIS TIME.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/ARJ
NEAR TERM...ARJ
SHORT TERM...26
LONG TERM...JMV
AVIATION...ARJ
