FXUS61 KRLX 120858
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
355 AM EST SAT DEC 12 2009
.SYNOPSIS...
HIGH PRESSURE DRIFTS OFF EAST COAST TODAY. OVERRUNNING MOISTURE
INCREASES FROM SOUTH TONIGHT INTO SUNDAY. LOW LEVEL MOISTURE LINGERS
SUNDAY NIGHT. COLD FRONT TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
A COLD BUT PEACEFUL DECEMBER ENVIRONMENT EARLY THIS MORNING.
INCREASED TEMPERATURES A DEGREE OR TWO FROM OUR PREVIOUS TRY FOR MID
AFTERNOON TODAY...FIGURING ON CLOUDS NOT INCREASING TOO FAST.
NO BIG CHANGES ON OUR THINKING WITH THE PRECIPITATION STARTING LATE
TONIGHT. QUESTION WITH THE BONE DRY AIR NEAR THE SURFACE...WHEN
WILL THE PRECIPITATION ON REMOTE SENSING ACTUALLY REACH US WELL
GROUNDED HUMANS? MAIN LIFT/FRONTOGENESIS FAVORS TO OUR
SE...ESPECIALLY WRN NC BY THE PREDAWN HOURS. UP HERE...HAVE LIQUID
PCPN AMOUNTS MOSTLY LESS THAN A QUARTER OF AN INCH IN OUR S BY 12Z
SUNDAY.
HAVE MINIMUM TEMPERATURES TONIGHT AROUND 05Z...THEN SLOWLY KEEPING
UP TOWARD 12Z. I TRIED TO HOLD TEMPERATURES NEAR THE FREEZING MARK A
FEW HOURS LONGER LATE TONIGHT IN THE BKW VCNTY AND IN PORTIONS OF
SOUTHEAST
OHIO...THUS KEEPING SOME POCKETS OF FREEZING RAIN THERE. NOT AN
IMPRESSIVE SE DAMMING SITUATION...BUT RATHER JUST THE EVAPORATIVE
COOLING EFFECT DUE TO THE INITIALLY DRY/LOW DEW POINT AIR.
THIS EVENT MAY LEAD TO SOME WINTER WEATHER OR FREEZING RAIN
ADVISORIES FOR LATE TONIGHT INTO SUNDAY MORNING...MAINLY FOR
POCAHONTAS AND EASTERN RANDOLPH. SINCE TIMING IS LATE TONIGHT...AND
NOT THINKING WATCH TO WARNING...STILL HAVE PLENTY OF TIME TO
REEVALUATE WITH 12Z RUNS TODAY...AND POST ANY ADVISORY HEADLINES
LATER THIS AFTERNOON.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
FREEZING RAIN THREAT ALONG THE EASTERN SLOPES WILL END BY 14Z OR SO
SUNDAY MORNING...AS WEAK CAD WILL BE OVERWHELMED BY WARM ADVECTION
ON SW FLOW. OVERALL PRECIPITATION COVERAGE WILL BE PEAKING AROUND
THIS TIME AS WELL...WITH BEST ISENTROPIC LIFT AND H300 CONVERGENCE
FROM RRQ OF UPPER JET DECREASING DURING THE MORNING. ADDITIONAL QPF
OF A TENTH TO A QUARTER INCH IN GENERAL. FAST FLOW QUICKLY PUSHES
H500 SHORTWAVE AWAY BY SUNDAY AFTERNOON. STILL...PLENTY OF MOISTURE
REMAINS TRAPPED UNDER INVERSION ALOFT...SO EXPECT LIGHT RAIN AND/OR
DRIZZLE TO LINGER INTO SUNDAY EVENING ESPECIALLY IN THE MOUNTAINS.
COULD TECHNICALLY SEE FREEZING RAIN/DRIZZLE IN THE VALLEYS TO THE
EAST ONCE AGAIN AFTER MIDNIGHT...BUT THIS WILL NOT BE OF MAJOR
CONCERN. BY 12Z MONDAY...ONLY A LITTLE SPOTTY DRIZZLE LEFT IN THE
MOUNTAINS. FOR SUNDAY/SUNDAY NIGHT TEMPERATURES...BLENDED GFS MOS
WITH PREVIOUS GRIDS...ENDED UP BELOW MET/MAV ON SUNDAY AND AT OR
ABOVE SUNDAY NIGHT.
MONDAY IS A TRANSITION DAY. EXPECT SOME LOW CLOUD TO LINGER IN THE
MORNING...BEFORE INVERSION BREAKS AND ALLOWS THESE CLOUDS TO DRY
UP. THIS WILL BE JUST IN TIME BEFORE CIRRUS STARTS BUILDING AHEAD
OF NEXT APPROACHING FRONT. ONLY MADE MINOR TWEAKS TO POPS FOR
MONDAY NIGHT FOR THIS BOUNDARY. PREFER THE ECMWF/GFS TIMING TO THE
SLOWER NAM. ALL RAIN MONDAY NIGHT AND EARLY TUESDAY WITH A WARM
COLUMN...WITH A CHANGEOVER TO SNOW ON THE BACKSIDE IN THE MOUNTAINS
LATER ON TUESDAY. LEFT GOING TEMPERATURES ALONE FOR MONDAY THROUGH
TUESDAY FOR NOW.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
MINOR DISCREPANCIES NOTED FROM MODELS DEPICTING COLD FRONT PUSHING
EAST LATE MONDAY NIGHT/EARLY TUESDAY. THE GFS IS FASTER WITH THE
VORT MAX ENERGY ALOFT...CLOSELY FOLLOWED BY THE ECMWF...AND THEN BY
THE GEM. HPC GUIDANCE SEEMS TO FOLLOW THE GFS/ECMWF WHICH ARE THE
PREFERRED SOLUTIONS.
MODELS SHOW DEEP SOUTHWEST FLOW BRINGING WARM ADVECTION TO THE AREA
MON NGT. WITH H850 TEMPS AROUND 3C...AND SOME CLOUDS MOVING
IN...EXPECT WARMER TEMPS THAN GMOS/HPC FOR LOWS ON TUE NGT.
CONSEQUENTLY...DELAYED THE ONSET OF WINTRY PCPN...ALLOWING
STRATIFORM RAIN TO SPREAD ACROSS THE AREA MON NGT. ON TUE...STRONG
H850 COLD AIR ADVECTION TAKES PLACE SUGGESTED BY GFS/ECMWF ALLOWING
FOR A NON DIURNAL TEMPERATURES TREND AND HIGH TEMPS IN THE UPPER
40S.
PCPN WILL TRANSITION TO WINTRY MIX OVER THE NORTHEAST MOUNTAINS TUE
EVENING....TO ALL SNOW LATER TUE NIGHT...WHILE THE REST OF THE
LOWLANDS WILL REMAIN LIQUID.
ON WED AND THU...NORTHWEST FLOW WILL TRANSFORM ANY LINGERING
MOISTURE LEFT WEST OF THE MOUNTAINS...AND COMING FROM THE GREAT
LAKES TO UPSLOPE SNOW. THEREFORE...KEPT CHANCE POPS AT ELEVATIONS
HIGHER THAN 2500 FEET.
GENERALLY WENT AT OR BELOW HPC NUMBERS FOR TEMPS THRU THE PERIOD.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
CLEAR THROUGH 18Z. SOME SMOKE AND SURFACE VSBY AROUND 5 MILES FROM
HOME HEATING POSSIBLE UNDER INVERSION THROUGH 14Z.
CLOUDS AT 5 TO 10 THSD FT BKN TO OVC INCREASING 22Z SATURDAY THRU
06Z SUNDAY FROM S AND SW. RAIN WITH POCKETS OF FREEZING RAIN
POSSIBLE AS FAR N AS HTS-CRW-BKW BY 06Z WITH VSBY LOWERING 3 TO 5
MILES.
AFTER 06Z SUNDAY...
IFR POSSIBLE IN RAIN EARLY SUNDAY. POCKETS OF FREEZING RAIN FROM
BKW NE TO E OF EKN UNTIL JUST AFTER DAWN SUNDAY.
IFR POSSIBLE IN LOW CLOUDS AND POSSIBLE DRIZZLE SUNDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/CL
NEAR TERM...KTB
SHORT TERM...CL
LONG TERM...ARJ
AVIATION...KTB
