FXUS61 KCTP 081046
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
546 AM EST TUE DEC 8 2009
.SYNOPSIS...
STRENGTHENING LOW PRESSURE WILL TRACK NORTHEAST FROM THE SOUTHERN
PLAINS TODAY TO THE GREAT LAKES BY WEDNESDAY. THIS SYSTEM WILL
BRING A WINTRY MIX TO CENTRAL PENNSYLVANIA TONIGHT AND EARLY
WEDNESDAY...FOLLOWED BY COLD AND BLUSTERY CONDITIONS THURSDAY.
HIGH PRESSURE WILL BUILD OVER THE STATE FRIDAY AND SATURDAY. A
STORM SYSTEM MAY PASS SOUTH OF PENNSYLVANIA LATE SATURDAY OR
EARLY SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REGIONAL RADAR LOOP SHOWING DIMINISHING AREA OF FLURRIES OVER THE
NORTHERN MTNS ASSOCIATED WITH WEAK TROUGH. SFC HI PRESSURE...CURRENTLY
LOCATED OVR SW PENN...SHOULD DOMINATE THE REGION FOR MOST OF
TODAY. HOWEVER...LOW LVL MOISTURE TRAPPED BENEATH INVERSION
RESULTING IN STUBBORN STRATOCU OVR THE MTNS. LOOKS LIKE WESTERN
HALF OF THE STATE WILL REMAIN CLOUDY TODAY...WHILE EARLY SUNSHINE
OVR THE SUSQ VALLEY GIVES WAY TO INCREASING CIRRUS IN ADVANCE OF FAST
APPROACHING WAVE TO OUR WEST.
LATEST SREF INDICATES LIGHT SNOW WILL OVERSPREAD SW PENN ARND
DUSK...AS OVERRUNNING/WAA SPREADS EAST IN ADVANCE OF MIDWEST LOW
PRES. CLOUD COVER SHOULD HOLD TEMPS IN THE 30S OVER MOST OF THE
REGION TODAY. EXCEPTION WILL BE LOWER SUSQ VALLEY...WHERE SUNSHINE
SHOULD PUSH READINGS INTO THE L40S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
WILL KEEP WINTER STORM WATCH INTACT OVR THE WESTERN MTNS TONIGHT
FOR POSSIBILITY OF SIG ICE ACCUMS. HOWEVER...LATEST ENSEMBLE PTYPE
PROBS...AS WELL AS MODEL SOUNDINGS...SUGGEST GREATEST THREAT OF
1/4 TO 1/2 INCH ICE ACCUMS WILL BE ACROSS THE LAUREL HIGHLANDS.
FURTHER N/NE ICE ACCRETION WILL BE LOWER...AS PERIOD OF SN WILL
PERSIST LONGER BEFORE TURNING TO FZRA/SLEET. DEPENDING ON 12Z
GUIDANCE...MAY NEED TO DOWNGRADE WATCH TO AN ADVISORY FOR ALL BUT
SOMERSET/CAMBRIA COUNTIES.
WINTER CLIMATOLOGY OF SFC LOW PASSING TO OUR WEST NOT FAVORABLE
FOR MORE THAN A FEW INCHES OF SNOW...AND LATEST MODEL SUGGESTS
THIS SYSTEM WILL FOLLOW THAT PATTERN. WARM LAYER ARND 750-800MB
PUSHES INTO CENTRAL PA OVERNIGHT...CHANGING SNOW TO A WINTRY MIX
ACROSS MOST OF CENTRAL PA. BASED ON EXPECTED SNOW ACCUMS AND MINOR
ICE ACCUMS...HAVE POSTED A WINT WX ADVISORY FOR MOST OF THE CWA
OUTSIDE OF THE WATCH. HAVE LEFT OUT AREAS SOUTH AND EAST OF
HARRISBURG...WHERE ENS PTYPES AND MODEL SFC TEMPS DON/T INDICATE
MUCH CHC OF FZRA. MIN TEMPS IN THE U20S/L30S LIKELY TO BE
REALIZED SHORTLY AFTER ONSET OF PRECIP THIS EVENING...THEN STEADY
OR SLOWLY RISING READINGS THEREAFTER UNDER CAA PATTERN.
WARM AIR ADVECTION WILL CONTINUE WED AS A LLVL 850MB JET IS PROGGED
ARND 40-50KTS PUSHES TEMPS NEAR 40 DEG...WHICH WILL PUSH AN
REMAINING FZRA OVER TO RA ACROSS THE CWFA. CONFIDENCE REMAINS HIGH
THAT A DRY WEDGE LIFTS INTO CENTRAL PA MIDDAY WED...AND COULD CUTOFF
PRECIP FOR MUCH OF THE AFTN. 500MB TROUGH AXIS QUICKLY PIVOTS THRU
MIDDAY WED...HOWEVER IT DOESN/T APPEAR THERMAL RIDGE DEPARTS UNTIL
LATE WED. ISALLOBARIC SFC PRESSURE RISE COUPLET OF ARND 2MB/3-HR IS
PROGGED...WHICH MOST LIKELY WILL FEATURE GUSTY WINDS WED AFTN/EVE
AND STEADILY FALLING TEMPS. ATTM EXPECT UPSLOPE SN/LAKE EFFECT SN
NOT TO OCCUR UNTIL LATE WED...HOWEVER RESONANCE TIME OVER THE LAKES
WILL BE MINIMIZED AT ONSET PROVIDING A CELLULAR LOOK TO PRECIP FOR
NW MTNS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
TRAILING COLD FRONT WILL PUSH THRU THE REGION WED EVE...WITH VERY
INTENSE W/NWSTRLY FLOW PUSHING INTO THE MID-ATLANTIC REGION
THUR/FRI/SAT. FOR SEVERAL DAYS ENSEMBLES GUIDANCE HAS BEEN
POINTING AT 850MB WINDS OF 40-50KTS...UNDER A VERY AGGRESSIVE UPR
LVL JET OF 140-160KTS. THE AFOREMENTIONED ELEMENTS ARE GOING TO
BLEND WITH 850MB TEMPS PROGGED AT -14 TO -16 DEG C THUR/FRI TO GENERATE
COOL AND BLUSTERY CONDS. ATTM FEEL GIVEN CONSID CLOUD COVER DURING
DAYLIGHT HOURS WILL HOLD TEMPS IN THE 20S/30S FOR THE END OF THE
WEEK...HOWEVER IF SKIES CAN CLEAR TEMPS WILL EASILY COOL OVERNIGHT.
SFC RIDGE IS PRESENTLY ADVERTISED BY ENSEMBLES FOR SAT/SUN...HOWEVER
CONFIDENCE IS LOW ATTM AS IT IS POSSIBLE RIDGE WILL BREAK DOWN
QUICKLY UNDER A PROGRESSIVE W-E FLOW AS A WEEKEND SHORTWAVE TRIES TO
DEVELOP ACROSS THE GULF OF MEXICO STATES. TEMPS REMAIN COOL THRU THE
UPCOMING WEEKEND.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
MVFR CIGS WILL SLOWLY ERODE TOWARD SUNRISE AS HIGH PRESSURE AND
SOME DRIER AIR MOVES INTO THE REGION. HIGH PRESSURE SHOULD
PROVIDE FOR LIGHT WINDS AND MOST IF NOT ALL AIRFIELDS GETTING
ABOVE 3KFT CIGS AROUND 10 AM.
A STRONG STORM APPROACHING FROM THE SOUTHWEST COULD SPREAD LIGHT SNOW
INTO SOUTHWESTERN PENNSYLVANIA BY LATER THIS AFTERNOON AND EVENING.
CLOUDS WILL RAPIDLY THICKEN AND LOWER DURING THE AFTERNOON AND
EVENING FROM SOUTHWEST TO NORTHEAST. PUT PROB30 FOR SNOW AT KJST-
KBFD- KAOO-KUNV FOR LATE IN THE DAY. PRECIPITATION SHOULD HOLD OFF
TO THE NORTH AND EAST UNTIL THE NEXT FORECAST PERIOD.
OUTLOOK...
TUE...SOME IFR BEFORE 14Z...MOSTLY VFR DURING THE DAY. LOWERING TO
MVFR IN SOUTHWEST IN THE AFTERNOON AND EVENING.
TUE NGT/WED...BCMG WDSPRD IFR IN SNOW/ICE/RAIN/FREEZING. RAIN
SHOULD MOVE NORTHWARD FROM SOUTHERN PA IN THE EARLY AM TO AT LEAST
CENTRAL AREAS BY MIDDAY OR EARLY AFTERNOON. SOME AREAS OF LLWS.
AREAS OF VLIFR CIGS AND VSBYS HEAVIER PRECIPITATION. CONDITIONS
SHOULD IMPROVE LATE IN THE DAY AND EVENING TO MVFR IN SOME
LOCATIONS.
WEDNGT/THUR...MVFR/IFR NORTH AND WEST IN SNOW SHOWERS MAINLY IN
THE MOUNTAINS. IMPRVG CENTRAL/EAST TO MAINLY VFR AND MVFR. STRONG
WESTERLY WNDS.
FRI/FRI NIGHT...MVFR WEST WITH SCATTERED SNOW SHOWERS IN MTNS OF
NORTHERN AND WESTERN PA. VFR MOST OF CENTRAL AND EAST.
SAT/SUN...VFR...POSSIBLY DECREASING TO IFR/MVFR SHOULD A SYSTEM
PROVIDE THE REGION WITH LIGHT SNOW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
WEDNESDAY FOR PAZ036-037-041-042-046-049>053-056>058-063.
WINTER STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY MORNING
FOR PAZ004>006-010>012-017>019-024>028-033>035-045.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...BEACHLER
AVIATION...GRUMM/GARTNER
