FXUS61 KRLX 022351
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
639 PM EST WED DEC 2 2009
.SYNOPSIS...
STRONG LOW PRESSURE SYSTEM MOVES TO NORTHEAST TONIGHT FOLLOWED BY
COLDER HIGH PRESSURE. A WEEKEND SYSTEM MAY BRUSH THE AREA WITH LIGHT
SNOW...THEN HIGH PRESSURE IS BACK SUNDAY AND MONDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
MODELS IN GENERAL AGREEMENT WITH DOWN SLOPE MIN AREA OF PCPN AND DRY
SLOT MOVING IN FOR THIS AFTERNOON AND TONIGHT. WIND GRADIENTS SHIFT
TO SOUTHWEST BY AROUND 06Z AS LOW MOVES THROUGH OHIO VALLEY. STRONG
GRADIENTS AND WINDS SHOULD PERSIST TONIGHT. AS HAS BEEN THE CASE
THUS FAR THIS FALL THE UPPER FLOW CONTINUES TO MAINTAIN A WEST TO
SOUTHWEST ORIENTATION OVER OUR REGION SO WE ARE NOT ABLE TO SET UP
WITH A GOOD NORTHWEST FLOW SITUATION FOR OUR AREA BEHIND COLD
FRONTS. HAVE KEPT THE AIR COLD ENOUGH FOR SNOW OUT OF OUR AREA
UNTIL THURSDAY NIGHT.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
MANY QUESTIONS ABOUND IN THE SHORT TERM. FIRST CONUNDRUM CENTERS
ARND UPSLOPE THU NIGHT AND FRI MORNING. AFTER LOOKING AT
EVERYTHING...NOT TOO IMPRESSED WITH UPSLOPE SN IN THE MTNS. LACK OF
SUSTAINED NW FLOW....MEAGER H85 TEMPS ARND -5 TO -7C...AND LACK OF
MOISTURE DEPTH POINT TO A LIGHT EVENT AT BEST. OF COURSE WITH CLOUD
TOPS ONLY GETTING TO ARND -5 TO -7C AND A SUBSTANTIAL DRY LAYER ABV
INVERSION...AM CONCERNED THAT MORE FRZ DZ THAN SN COULD BE REALIZED
IN THE MTNS. LEFT AS SN FOR NOW...HOWEVER THIS MAY CHANGE AS THE
NEAR TERM MODELS GET TO IT. OUTSIDE OF THE MTNS...SOME -DZ POSSIBLE
THU EVE...OTHERWISE CLOUDS WILL HANG AROUND OVERNIGHT.
THE NEXT QUESTION IS WHAT TO DO WITH SYNOPTIC SYS FOR SAT. MODELS
HAVE BEEN WAFFLING BACK AND FORTH WITH THE TRACK OF THE WEAK SFC
SYS...WITH MOST OF THE 12Z RUNS TAKING A TRACK OFFSHORE. NAM IS ON
THE WESTERN SIDE OF GUIDANCE...CLOSER TO THE COAST. THIS WOULD TAKE
MOST OF THE QPF WELL EAST OF THE CWA. HOWEVER...THE S/W TROF THAT
SWINGS THROUGH ON SAT BRINGS IT OWN LIFT AND QPF...WITH THE MODELS
TRACKING A STOUT VORT MAX JUST SOUTH OF THE AREA. THUS EXPECTING
ANOTHER SHIELD OF PCPN TO BREAK OUT ACROSS THE WESTERN
PIEDMONT/APPALACHIANS. THERE WILL BE SOMEWHAT OF A SHARP
GRADIENT...WITH NOT MUCH ALONG AND WEST OF THE OH RVR. KEPT CHC POPS
IN THE MTNS...TAILING OFF QUICKLY IN THE KANAWHA VALLEY...WITH NO
POPS WEST OF THE OH RVR. THERMAL PROFILES AND LOWLEVEL NORTHERLY
WIND INDICATE ALL SN WITH THIS...HOWEVER QPF REMAINS LIGHT. CODED UP
-SN FROM THE MTNS TO JUST WEST OF THE I79 CORRIDOR WITH FLURRIES TO
THE OH RVR. FOR AMTS...MAYBE AND INCH OR TWO IN THE MTNS...DWINDLING
TO PERHAPS A DUSTING MAKING IT TO I79 CORRIDOR. TROF MOVES EAST OF
THE AREA SAT EVE...TAKING PCPN WITH IT.
FOR TEMPS...USED A BLEND OF MAVBC/INHERITED TEMPS INITIALLY. COULD
BE A LIL TOO COLD WITH MINT THU NIGHT...AS THE NAM IS SLOWER TO
BRING IN THE COLDER AIR AND LINGERING CLOUDS. HIGHS FRI WILL ONLY
GET INTO THE UPR 30S/NEAR 40 ACROSS THE SE OH/WV LOWLANDS...WITH
LWR/MID 30S ACROSS THE MTNS. TEMPS A LIL TRICKY FRI NIGHT...AS
TIMING OF CLOUDS MOVING IN FROM THE SOUTH CRITICAL TO HOW LOW THEY
GO. BELIEVE ALL AREAS WILL GET DOWN INTO THE 20S...WITH LOWER 20S SE
OH. UNDERCUT GUIDANCE FOR SAT WITH CLDS/-SN IN THE AIR. MAY STILL BE
A FEW DEGREES TOO WARM EAST OF THE OH RVR. GENERALLY EXPECTING TEMPS
TO REMAIN BELOW FREEZING ACROSS THE MTNS...WITH TEMPS TRYING TO GET
INTO THE MID 30S FOR THE LOWLANDS/SE OH.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
FOLLOWED HPC IDEAS THROUGH THIS PERIOD. THEY USED A
MULTI-MODEL/ENSEMBLE BLEND TO ACCOUNT FOR STRENGTH/TIMING
DIFFERENCES. HAVE A SHORT PERIOD OF UPSLOPE SNOW SHOWERS ON THE
BACK SIDE ON SATURDAY NIGHT...BUT THESE SHOULD END QUICKLY AS
MOISTURE COLLAPSES QUICKLY AHEAD OF APPROACHING HIGH. EXPECT CLOUDS
TO DECREASE THEREAFTER.
SURFACE HIGH REMAINS IN CONTROL FOR SUNDAY/MONDAY...WITH ZONAL FLOW
ALOFT. THIS PATTERN WILL PROMOTE A MODERATION IN
TEMPERATURES...EVEN THOUGH VALUES WILL REMAIN A BIT BELOW NORMAL.
ALSO FORESEE BOUTS OF MID/HI CLOUDS IN THE FAST FLOW ALOFT...BUT
KEEPING DRY POPS.
SYSTEM THEN EJECTS FROM THE ROCKIES ON TUESDAY AND HEADS FOR THE
OHIO VALLEY ON WEDNESDAY. COULD SEE SOME WARM ADVECTION-DRIVEN
PRECIPITATION ON TUESDAY BEFORE MAIN LOW CENTER APPROACHES ON
WEDNESDAY. PRECIP TYPE STILL IN QUESTION ON THE FRONT SIDE AT
LEAST...KEPT A RAIN/SNOW POSSIBILITY. TEMPERATURES FOLLOW HPC
NUMBERS WITH TWEAKS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
LOW LEVEL WINDS REMAIN THE MAIN STORY 00Z TO 06Z. HAVE COLD FRONT
SWINGING THROUGH AROUND 03Z HTS TO 07Z EKN...UNDER THE LOW PRESSURE
LIFTING N THROUGH OHIO DURING THE SAME TIME FRAME. BRIEF CONVECTIVE
SHOWERS POSSIBLE ALONG THAT FRONT...COULD NOT COMPLETELY RULE OUT
SOME THUNDER DUE TO UPPER AIR SUPPORT WITH THAT BRIEF LINE.
AS SURFACE WINDS VEER TO SOUTHWEST IN WAKE OF THE FRONT...CEILINGS
WILL LOWER OVER THE WESTERN LOWLANDS. BY 08-12Z HAVE WIDESPREAD
CEILINGS AROUND 1 THSD FT TO 15 HND FT OVC WITH VSBY 3 TO 5 MILES IN
SPOTTY LIGHT RAIN OR DRIZZLE. LITTLE IMPROVEMENT DURING THE DAY ON
THURSDAY. VSBY MAY BE AOB 3 MILES OVER THE HIGHER MOUNTAINS FOR
MUCH OF THE DAY.
AFTER 00Z FRIDAY...
IFR CONDITIONS POSSIBLE IN THURSDAY NIGHT OVER MOUNTAINOUS COUNTIES
IN LOW CLOUDS AND LIGHT MIXED PRECIPITATION.
IFR POSSIBLE AGAIN IN LIGHT SNOW LATE FRIDAY NIGHT INTO SATURDAY
MORNING OVER THE MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR WVZ033>038-046-
047.
OH...NONE.
KY...NONE.
VA...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR VAZ003-004.
&&
$$
SYNOPSIS...KTB/CL/AAR/30
NEAR TERM...AAR
SHORT TERM...30
LONG TERM...CL
AVIATION...KTB
