FXUS61 KRLX 071949
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
240 PM EST MON DEC 7 2009
.SYNOPSIS...
PRECIPITATION ASSOCIATED WITH WARM FRONT TUESDAY AFTERNOON AND
NIGHT. DEEPENING LOW PRESSURE LIFTS NORTHEAST INTO GREAT LAKES
WEDNESDAY WITH FRONT PASSING.
&&
.NEAR TERM /THROUGH TONIGHT/...
POTENTIAL FOR SPRINKLES/FLURRIES WILL CONTINUE THIS AFTERNOON AND
EARLY THIS EVENING AS POORLY DEFINED FORCING MECHANISMS PROVIDE JUST
ENOUGH LIFT TO SQUEEZE MOISTURE OUT OF THE ATMOSPHERE. WEAK HIGH
PRESSURE HOLDS ON AT THE SURFACE...BUT DOES NOT QUITE HAVE ENOUGH
HELP ALOFT TO ERADICATE THE LOW AND MID LEVEL MOISTURE. WITH LESS
THAN OUTSTANDING UPSLOPE CONDITIONS BRIEFLY MAKING AN APPEARANCE
LATER TONIGHT...MOISTURE DEPTH...OR LACK THEREOF...BRINGS ON THE
POTENTIAL OF FREEZING DRIZZLE ACROSS THE EASTERN HIGHLANDS AND
EASTERN SLOPES OF OUR MOUNTAINS. DO NOT THINK THIS IS THE BEST SETUP
FOR FREEZING DRIZZLE...SO HAVE ADDED THIS CATEGORY TO THE SLIGHT
CHANCE OF LIGHT SNOW SHOWERS.
NEXT SYSTEM ADVECTS NORTHEAST IN A STRONG SOUTHWESTERLY FLOW ALOFT
TUESDAY...WITH THE ATMOSPHERE BECOMING SATURATED FROM THE TOP DOWN.
THIS MAKES THE TIMING OF THE START OF THE PRECIPITATION A LITTLE BIT
TRICKY...BUT ONCE PRIMING OCCURS...IT WILL MOST LIKELY BECOME A
STEADY SHIELD OF RAIN. POP GRADIENT COULD EASILY BECOME TIGHTER AS
THE EVENT APPROACHES. NAM AND LOCALLY RUN MODELS PERFORMED PRETTY
WELL WITH THE TIMING OF THE MOISTURE WITH THE LAST SIMILAR EVENT.
WILL LOOK FOR THE TEMPERATURES TO RISE THROUGH THE DAY TUESDAY IN
THE WARM AIR ADVECTION WITH THE SURFACE LOW PASSING FROM THE
SOUTHERN PLAINS INTO THE SOUTHERN GREAT LAKES. WARM AIR ADVECTION
WILL BE MODEST HOWEVER AS THE SURFACE FLOW WILL STUBBORNLY REMAIN
EAST NORTHEASTERLY AND WILL NOT COME AROUND TO THE SOUTHEAST UNTIL
AFTER 21Z OR SO ON TUESDAY. AS THE FLOW DOES BECOME
SOUTHWESTERLY...WILL SEE PLACES LIKE BKW AND SNOWSHOE DROP A FEW
DEGREES FROM 21Z TO 00Z.
LOOKS LIKE THE GUIDANCE NUMBERS ARE JUST A DEGREE OR TWO COOL FOR A
FEW SITES...AND TWEAKED UPWARDS SLIGHTLY FOR A GOOD NUMBER OF
LOCATIONS.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
LOW PRESSURE WILL DEEPEN AS IT MOVES FROM THE SOUTHERN PLAINS INTO
EASTERN CANADA. AS THE LOW MOVES NORTHEAST...A COLD FRONT WILL PUSH
EAST ON WEDNESDAY.
LATEST MODELS SUGGEST PRECIPITATION ASSOCIATED WITH THE LOW WILL
MOVE INTO REGION EARLIER THAN PREVIOUS THOUGHT...SO HAVE BUMPED UP
POPS AT BEGINNING OF PERIOD. STILL LOOKS LIKE THE PRECIPITATION
SHOULD BEGIN AS SLEET/FREEZING RAIN ACROSS PORTIONS OF
RANDOLPH/POCAHONTAS COUNTIES. WITH TEMPERATURES EXPECTED TO WARM
DURING THE NIGHT...PRECIPITATION WILL SWITCH OVER TO ALL RAIN.
WHILE THERE WILL BE SOME SLICKS SPOTS ACROSS THE TWO
AFOREMENTIONED COUNTIES...ANY WATCHES/WARNINGS ARE BASED ON
COUNTY-BASED ACCUMULATIONS AND WILL NOT ISSUE ANYTHING AT THIS
TIME. LATER SHIFTS MAY NEED TO ISSUE AN ADVISORY.
BASED ON MODEL INSTABILITY FORECASTS AND SPC THUNDERSTORM
OUTLOOKS...HAVE TRIMMED MENTION OF THUNDERSTORMS TO FAR SOUTHERN
PORTIONS OF REGION TUESDAY NIGHT.
BEHIND COLD FRONT...MUCH COLDER AIR WILL FILTER IN WEDNESDAY.
STRONG PRESSURE GRADIENT SUGGESTS WINDS WILL BE QUITE STRONG AND
HAVE BUMPED WIND SPEEDS AND ASSOCIATED WIND GUSTS UPWARD. COULD SEE
WIND GUSTS NEAR 45 MPH ACROSS PORTIONS OF SOUTHWEST OHIO/HIGHER
ELEVATIONS OF THE WEST VIRGINIA MOUNTAINS. WILL NOT ISSUE ANY WIND
WATCHES AT THIS TIME. HOWEVER...FEEL WIND ADVISORIES MAY BE NEEDED
ACROSS MUCH OF THE AREA.
PRECIPITATION SHOULD THEN TAPER OFF FROM THE SOUTHWEST BEGINNING
LATE TUESDAY NIGHT THROUGH THE REMAINDER OF THE PERIOD. IT WILL
REMAIN QUITE WINDY WEDNESDAY NIGHT INTO THURSDAY. HOWEVER...SPEEDS
SHOULD BE LESS THAN THOSE EXPECTED ON WEDNESDAY.
PREVIOUS TEMPERATURE GRIDS ARE SIMILAR TO LATEST TEMPERATURE
GUIDANCE...AND WILL GENERALLY BE FOLLOWED WITH SOME TWEAKS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
BY THURSDAY NIGHT...THE STRONG LOW PRESSURE SYSTEM WILL BE LIFTING
THRU THE GREAT LAKES AND NEW ENGLAND. A HIGH PRESSURE BUILDS IN
BRINGING A VERY COLD AND DRY AIR MASS UNDER H8 WINDS AROUND 45 KNOTS
THU NIGHT. THEREFORE...EXPECT DRY WEATHER CONDITIONS WITH CLEAR
SKIES SPREADING FROM THE WEST THROUGH FRIDAY. GUSTY CONDITIONS WILL
STILL POSSIBLE MAINLY HIGHER ELEVATIONS THURSDAY NIGHT...DECREASING
BY FRIDAY. CLEAR SKIES WILL ALLOW IDEAL RADIATIONAL COOLING FOR EVEN
COLDER TEMPERATURES THURSDAY NIGHT.
ANOTHER UPPER WAVE MOVES FROM THE SOUTHERN PLAINS...EAST AND
NORTHEAST INTO THE AREA...TO BRING A MORE SOUTHERLY FLOW INCREASING
TEMPERATURES AND HUMIDITY ON SUNDAY. INTRODUCED SLIGHT CHANCE POPS
ACROSS THE SOUTHERN HALF OF THE AREA...FRI NIGHT...INCREASING TO
CHANCE POPS SATURDAY AND SAT NIGHT. PCPN EXPECTED TO BE ALL SNOW FRI
NIGHT...CHANGING TO RAIN AND MIX SAT ACROSS THE LOWLANDS AS WARM
ADVECTION TAKES PLACE. HOWEVER...PCPN CHANGES BACK TO SNOW SAT NIGHT
AREA WIDE. GOING A BIT FASTER THAN THE LATEST GFS/ECMWF
SOLUTION...MORE LIKE THE ECMWF OLDER SOLUTION. STICK CLOSER TO HPC
TEMPERATURES TWEAKING DOWN FEW DEGREES LOW TEMPS THROUGH THE PERIOD.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
LOOKING AT AN OSCILLATION BETWEEN VFR AND MVFR CEILINGS INTO
TONIGHT...WHEN CEILINGS SHOULD STAY VFR BEFORE THE NEXT SYSTEM
ARRIVES TUESDAY. ISOLATED LIGHT SPRINKLES/SNOW SHOWERS WILL
CONTINUE TODAY...AND ANY VISIBILITY ISSUES SHOULD BE BRIEF...IF
ANY OCCUR AT ALL.
THE NEXT SYSTEM MOVES IN FROM THE SOUTHWEST AND MOISTENS FROM THE
TOP DOWN. STEADY RAIN CAN BE EXPECTED AFTER 15Z IN THE COAL FIELDS.
AFTER 18Z TUESDAY...
IFR IN MOSTLY RAIN LATE TUESDAY INTO WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/JSH/ARJ
NEAR TERM...26
SHORT TERM...JSH
LONG TERM...ARJ
AVIATION...26
