FXUS61 KRLX 052113
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
351 PM EST SAT DEC 5 2009
.SYNOPSIS...
SNOWY SYSTEM GRADUALLY EXITS BY THIS EVENING. HIGH PRESSURE SUNDAY.
WEAK FRONT MONDAY AFTERNOON. STRONGER SYSTEM LATE TUESDAY INTO
WEDNESDAY...BRINGING MIXED WINTRY PRECIPITATION.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
PEAK OF OUR CURRENT SNOW EVENT IS PASSING THROUGH THE AREA AT
MIDDAY...AND WILL NOW START WINDING DOWN IN THE WESTERN LOWLANDS.
HOWEVER...SNOW REPORTS SO FAR...AND A FEW MORE HOURS OF MODERATE TO
HEAVY SNOW IN THE MOUNTAINS...WARRANTED UPGRADE TO WINTER STORM
WARNING FOR CENTRAL TO NORTHERN WV MOUNTAINS. OVERALL...LOOKING AT
STORM TOTALS OF 2-4 INCHES IN ADVISORY AREA...AND 4-8 INCHES IN
WARNING AREA.
ON THE RUC MODEL...700MB PETTERSSEN FRONTOGENESIS AXIS...AS WELL AS
AXIS OF Q VECTOR CONVERGENCE AT 300MB...COINCIDES WELL WITH FINAL
BAND OF HEAVIER SNOW CURRENTLY JUST EAST OF CLARKSBURG-CHARLESTON
LINE. THIS AXIS WILL FINISHING MOVING THROUGH THE EASTERN CWA THE
NEXT FEW HOURS...AND EXIT THE NORTHERN MOUNTAINS BY 21Z OR SO. BY
THIS TIME...DEEPER MOISTURE WILL BE GONE...LEAVING ONLY LINGERING
FLURRIES AND BRIEF LIGHT UPSLOPE SNOW SHOWERS IN THE MOUNTAINS.
THOUGH SNOW WILL FINISH OFF...ANY UNTREATED WET ROADWAYS IN THE AREA
WILL ICE OVER THIS EVENING AS TEMPERATURES DIVE WELL BELOW FREEZING.
WITH FRESH SNOW FOR MOST OF AREA AND RAPID CLEARING EXPECTED THIS
EVENING...FOLLOWED BY BUILDING SURFACE HIGH...IDEAL CONDITIONS FOR
RADIATIONAL COOLING LATER TONIGHT. WENT BELOW MODEL GUIDANCE FOR
TEMPERATURES...AND FOR SOME SPOTS DAILY RECORD LOWS WILL BE
APPROACHED WITHIN A FEW DEGREES BY DAWN SUNDAY.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
SURFACE HIGH PRESSURE IN CONTROL AT THE START OF THIS PERIOD. ZONAL
FLOW ALOFT...WARM ADVECTION...AND A BIT OF UPPER LEVEL MOISTURE WILL
ALLOW FOR MID/HIGH CLOUDS DURING THE DAY. HELD TEMPERATURES TOWARDS
THE LOW END OF GUIDANCE IN THE EAST...WHERE MUCH OF THE HEATING
ENERGY WILL GO INTO MELTING SNOW. CLOSER TO A CONSENSUS OF MOS IN
THE WEST.
SUNDAY NIGHT/MONDAY WILL FEATURE A SHEARING H500 SHORT WAVE LIFTING
FROM THE CENTRAL PLAINS AT 00Z MONDAY INTO THE SOUTHERN GREAT LAKES
BY 00Z TUESDAY. WEAK FRONTAL BOUNDARY WILL BE PUSHED ACROSS REGION
DURING THE DAY MONDAY. STILL PREFER THE FASTER GFS OVER THE NAM
SCENARIO GIVEN THE ZONAL FLOW. IN ANY CASE...MOISTURE BECOMES QUITE
LIMITED AS THE SHORTWAVE SHEARS...CUTTING OFF THE MOIST SOUTHWEST
INFLOW. LITTLE MIDLEVEL SUPPORT AS WELL...WITH ONLY THE
NORTHERN/WESTERN COUNTIES GETTING GRAZED BY THE ACTUAL SHORTWAVE.
THUS...KEPT POPS IN THE SLIGHT TO VERY LOW CHANCE CATEGORY...WITH
CORRESPONDINGLY LOW QPF. KEPT RAIN/SNOW MIX IN THE GRIDS FOR NOW.
WENT FOR A MORE NARROW DIURNAL RANGE SUNDAY NIGHT/MONDAY THAN
SUGGESTED BY MOS...WARM SIDE BY NIGHT AND COOL SIDE BY DAY...GIVEN
EXPECTED CLOUD COVER.
THERE MAY BE A BRIEF PERIOD OF UPSLOPE SHOWERS MONDAY NIGHT IN THE
MOUNTAINS...AS COLDER AIR BRIEFLY TRIES TO LEAK IN ON NORTHWEST
FLOW. KEPT THESE POPS LOW AS WELL...AND EXPECTING A DRY CWA BY 12Z
TUESDAY...JUST IN TIME FOR RAMP UP TO MORE SIGNIFICANT MIDWEEK
SYSTEM.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
MEDIUM RANGE MODELS ARE SHOWING A SIGNIFICANT LOW PRESSURE SYSTEM
LIFTING UP THROUGH THE OHIO VALLEY MID WEEK...WITH LATEST RUNS
SLOWING ITS ASSOCIATED WARM FRONT AND ONSET OF PRECIP JUST A LITTLE.
THUS...HAVE TRIMMED POPS BACK TUESDAY TO MAINLY ACROSS THE SOUTH
LATER ON THE DAY TUESDAY...THEN RAPIDLY OVERSPREAD THE AREA TUESDAY
EVENING. THE TRACK OF THE LOW ITSELF IS THRU THE WESTERN OHIO
VALLEY...AND INTO MICHIGAN BY LATER IN THE DAY WEDNESDAY. THIS LOW
TRACK...AND STRONG HIGH PRESSURE RIDGING EAST OF THE MOUNTAINS...
WILL INHIBIT THE WARM FRONT FROM LIFTING NORTH THRU THE NORTHERN
MOUNTAINS TUESDAY NIGHT.
THUS...COLD AIR WILL BE TOUGH TO DISLODGE TUESDAY NIGHT AND EARLY
WEDNESDAY IN THE NORTHERN MOUNTAINS. FOR DETAILS...GOING WITH THE
COLDER GFS 850/925 TEMPS WITH THIS SYSTEM TUESDAY NIGHT AND EARLY
WEDNESDAY. THIS SCENARIO WILL KEEP MUCH OF THE PRECIP IN THE
FREEZING/FROZEN FORM TUESDAY NIGHT...ESPECIALLY ON EAST FACING
SLOPES OF THE NORTHERN MOUNTAINS. ELSEWHERE...WARMER AIR WILL RUSH IN
FAST ENOUGH TO GIVE MAINLY RAIN TUESDAY NIGHT AND EARLY WEDNESDAY
AHEAD OF THE WARM FRONT. BY MID MORNING WEDNESDAY...WARMER AIR WILL
FINALLY WIN OUT OVER THE ENTIRE AREA...WITH RAIN TURNING TO RAIN
SHOWERS IN THE WARM SECTOR. PURPOSELY KEPT QPF AMOUNTS LOW ENOUGH TO
PREVENT MENTION OF HEAVY ICE/SNOW IN THE NORTHERN MOUNTAINS AT THIS
EARLY DATE...BUT THE POTENTIAL IS THERE.
THE FOLLOWING COLD FRONT WILL RACE ACROSS THE AREA LATER ON
WEDNESDAY. RAIN SHOWERS ON WEDNESDAY WILL RAPIDLY CHANGE TO SNOW
SHOWERS WEDNESDAY EVENING. THERE WILL LIKELY BE SOME SNOW
ACCUMULATIONS ACROSS MUCH OF THE AREA BY THURSDAY
MORNING...ESPECIALLY MOUNTAINS. HIGH PRESSURE BUILDS IN THURSDAY
WITH SNOW SHOWERS ENDING.
THIS WILL BE A WINDY SYSTEM GIVEN THE STRENGTH OF THE LOW. LOOK FOR
GUSTY SOUTH WINDS DEVELOPING TUESDAY AND TUESDAY NIGHT...ESPECIALLY
MOUNTAIN RIDGETOPS. GUSTY WINDS WILL CONTINUE THRU WEDNESDAY...AND
AFFECT MORE OF THE AREA...AS WINDS TURN MORE WESTERLY WITH THE COLD
FRONT. DID NOT WANT TO PUSH ADVISORY WIND CRITERIA AT THIS EARLY
DATE...BUT THE POTENTIAL IS THERE MAINLY FOR RIDGETOPS.
BEYOND THURSDAY...ANOTHER SYSTEM WILL AFFECT THE AREA FRIDAY AND
SATURDAY...WITH MORE UNSETTLES WEATHER AND BELOW NORMAL TEMPS.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
PEAK OF SNOW EVENT WILL BEGIN EXITING THE AREA...AS ASSOCIATED UPPER
DISTURBANCE LIFTS TO THE NORTHEAST. IFR OR WORSE SNOW WILL FINISH AT
OR VERY SOON AFTER 18Z ALONG THE OHIO RIVER. BY 21Z...IFR CIGS/VIS
WILL ONLY REMAIN IN THE MOUNTAINS...AND BY 00Z...RAPID CLEARING WILL
ALREADY BE UNDERWAY IN THE LOWLANDS...WHILE MOUNTAINS STILL BARELY
LINGER TO MVFR CIGS AND/OR VIS. VFR 00Z-18Z SUNDAY...THOUGH WITH
VERY COLD MORNING EXPECTED...WILL HAVE TO WATCH FOR POTENTIAL
SMOKE-CAUSED MVFR VIS IN THE MORE SHELTERED VALLEYS SUCH AS THE
TYGART...FROM WOOD BURNING-BASED HEATING.
AFTER 18Z SUNDAY...
IFR IN WINTRY MIX POSSIBLE LATE TUESDAY INTO WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
WVZ015>020-026>032-035-039-040.
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
WVZ036>038-046-047.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...CL/MDP/JMV
NEAR TERM...MDP
SHORT TERM...CL
LONG TERM...JMV
AVIATION...MDP
