FXUS61 KCTP 252101
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
401 PM EST WED NOV 25 2009
.SYNOPSIS...
A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION THIS AFTERNOON AND
THIS EVENING. A STRONGER COLD FRONT WILL CROSS THE REGION
THANKSGIVING EVENING FOLLOWED BY COLDER...BLUSTERY AND UNSETTLED
CONDITIONS THROUGH FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A LOW OVERCAST WITH OCCASIONAL SHOWERS OR PATCHY DRIZZLE WILL
CONTINUE TO AFFECT MUCH OF CENTRAL PA INTO THE EVENING. A WEAK
COLD FRONT IS ENTERING MY WRN COUNTIES...AND WILL FINALLY BRING
THE WIND SHIFT WE NEED TO START TO SCOUR OUT THE DREARY CONDITIONS
WE HAVE BEEN PLAGUED WITH ALL WEEK.
THE WEAK FRONT WILL MOVE EAST AND BRING SHOWERS AND GENERALLY
LIGHT TO NEGLIGIBLE PRECIP...AVERAGING 0.10" OR LESS THIS
AFTERNOON AND EVENING.
MAX TEMPS THIS AFTERNOON WILL BE ABOUT 6 OR 7F ABOVE NORMAL...
RANGING FROM THE UPPER 40S ACROSS THE MTNS...TO THE MID 50S IN THE
SE VALLEYS.
FOLLOWING THIS FRONT...A FEW BREAKS IN THE OVC SHOULD OCCUR TONIGHT
THROUGH THANKSGIVING MORNING...AS LIGHT WESTERLY FLOW FINALLY
TAKES OVER. AREAS THAT DECOUPLE OVERNIGHT AND MANAGE ANY KIND OF
CLEARING WILL BECOME VULNERABLE TO FOG. THOSE THAT KEEP CLOUDS AND A
LIGHT WEST WIND WILL BE SPARED. WILL GO FOR PATCHY FOG LATE AT
NIGHT BUT CONFIDENCE IS LOW.
MIN TONIGHT WILL DIP INTO THE MID/UPR 30S ACROSS THE CENTRAL AND
NORTH...WITH DAYBREAK TEMPS IN THE LOWER 40S FOUND ACROSS THE SUSQ
VALLEY.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
AFTER A RELATIVELY BRIGHT START TO THANKSGIVING DAY...ESPECIALLY
COMPARED TO THE PREVIOUS 3 DAYS...A SHARP TRANSITION WILL BEGIN
WITH THE DEVELOPMENT OF THICKENING CLOUDS/SHOWERS LATER IN THE DAY
IN THE WEST AHEAD OF A STRONG COLD FRONT.
NEW OPERATIONAL GUIDANCE KEEPS MUCH OF MY FORECAST AREA DRY MOST
OF THE DAY WITH HIGHS STILL QUITE MILD...SOME 5 TO 10 DEG ABOVE
NORMAL. 09Z SREF SHOWS MY NWRN ZONES WITH THE HIGHEST POPS BY 00Z
SO I TRIED TO TAPER RAIN CHANCES FROM HIGHEST IN THE WEST TO
RELATIVELY SMALL CHANCES IN CENTRAL AND EASTERN AREAS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
OPERATIONAL MODELS...AND SHORT RANGE ENSEMBLE GUIDANCE STILL SHOW
SOME UNCERTAINTY WITH RESPECT TO THE TRACK OF THE DEEPENING UPPER
LOW AND TIMING OF THE SFC LOW BOMBING LATER THURSDAY NIGHT AND
FRIDAY AS IT MOVES NORTH NORTHEAST (FROM JUST EAST OF THE MID
ATLANTIC COAST TO THE COAST OF MAINE BY 00Z SAT).
SINCE I WORKED SUNDAY...THERE HAS BEEN QUITE A BIT OF SPREAD IN
SOLUTIONS. MOST MODELS AND HPC HAVE BEEN LEANING ON THE MORE
NORTHERN TRACK. THE NAM MODEL TODAY IS FURTHER SOUTH AND WETTER.
IF ONE WENT WITH THIS...UPWARDS OF 6 INCHES OF SNOW COULD OCCUR...
AND ONE WOULD HAVE TO AT LEAST THINK ABOUT A LATE THIRD PERIOD
WATCH...BUT GIVEN THAT THIS A WAYS OUT...AND OTHER MODELS HAVE
THE UPPER LEVEL LOW FURTHER NORTH AND LESS QPF...I LEFT THE
FCST CLOSE TO WHAT WAS OUT THERE. I DID EDGE AMTS DOWN A TAD
ACROSS THE FAR NE THU NIGHT...AS IT MAY TAKE A WHILE FOR THE
COLD AIR TO GET IN THERE. LEFT THE HIGHLANDS AS IS. LEFT THE
SNOW AMTS AS IS FOR FRIDAY...BUT ADJUSTED THE POPS AND WEATHER
BREAKOUTS SOME.
OVERALL...SFC LOW AND MOST OF THE MOISTURE IS TOO FAR EAST TO
GET A LOT OF QPF...MAIN CONCERN IS HEAVY WET SNOW FROM DYNAMIC
COOLING AND DEFORMATION FORCING.
THE MAIN OTHER ADJUSTMENT WAS ON POPS ON THU NIGHT...GIVEN POPS
FROM OTHER OFFICES AND LACK OF QPF. STILL MUCH HIGHER THAN THE
12Z GFS POPS.
OVERALL...STILL AGREE WITH HPC SNOW GRAPHICS THAT SUPPORT A FEW
INCHES OF SNOW ACROSS THE HIGHER TERRAIN OF WESTERN PENN THU NIGHT
AND FRIDAY (WITH LOCALLY AROUND 4 INCHES POSSIBLE OVER AN 18 HOUR
PERIOD ACROSS THE UPSLOPE AREAS OF THE LAUREL HIGHLANDS)...
AND SEVERAL HOURS LATER ACROSS THE MTNS NORTH AND EAST OF KIPT
(MAINLY MORE TOWARD 12Z-18Z FRIDAY).
A GUSTY NORTHWEST WIND WILL DEVELOP FRIDAY AS THE LOW INTENSIFIES
OFF THE SRN NEW ENGLAND COAST...QUICKLY TIGHTENING THE LLVL PRESS
GRADIENT. 3 HOURLY PRESSURE CHANGES WILL RAMP UP TO 3-4 MB DURING
THE DAY - PRODUCING WIND GUSTS OF AROUND 30 MPH.
SFC RIDGING WILL BUILD NEWD SAT/SUN...PROVIDING IMPROVING CONDS AND
MODERATING TEMPS AS LLVL FLOW VEERS AROUND TO THE SW.
SEVERAL WEAK FRONTS MOVE ACROSS THE REGION EARLY NEXT WEEK...BUT
NOTHING BIG FCST. PERHAPS LATER IN THE WEEK...BUT SOLUATION FOR
THU...LOOKS TO BE STILL ON THE MILD SIDE FOR THE MOST PART.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
MOIST SE/S FLOW OF AIR WILL CONTINUE TO PRODUCE WIDESPREAD
IFR/MVFR CLOUDS AND REDUCED VSBYS IN AREAS OF DRIZZLE OR LIGHT
RAIN THROUGH THE DAY...ESPECIALLY IN THE EAST. A BAND OF SHOWERS
WILL SLIDE FROM W-E ACROSS THE REGION FROM MID DAY THRU MID
AFTERNOON...WHICH WILL BRING A RETURN OF MVFR/IFR CIGS FOR
SEVERAL HOURS IN THE WEST AS WELL. CONDITIONS WILL GRADUALLY
IMPROVE TONIGHT INTO THU ACROSS THE WEST...BUT MVFR CIGS WILL
LIKELY LINGER INTO THU IN THE EAST.
A SIG COLD FRONT FOLLOWED BY A POTENT UPPER LOW WILL MOVE THROUGH
LATE WEEK BRINGING COLD/BLUSTERY AND DETERIORATING CONDITIONS
AGAIN THU NIGHT THRU SAT. WORST CONDITIONS WILL TEND TO BE OVER
THE WESTERN AND NORTHERN HIGH TERRAIN WHERE SNOW SHOWERS ARE
LIKELY TO BRING FREQUENT PERIODS OF IFR.
OUTLOOK...
THU...MVFR WEST WITH SCATTERED SHOWERS/VFR EAST.
THU NIGHT-FRI...IFR WEST WITH FREQUENT RAIN/SNOW SHOWERS. MVFR
CENTRAL AND EASTERN AREAS WITH SCATTERED RAIN/SNOW SHOWERS.
FRI NIGHT-SAT...IFR/MVFR IN THE WEST/NORTH WITH FREQUENT HIGH
TERRAIN SNOW SHOWERS. VFR OVER CENT/EAST WITH BRIEF MVFR IN
PASSING RAIN/SNOW SHOWERS.
SUN...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...MARTIN/STEINBUGL
AVIATION...LA CORTE
