FXUS61 KCTP 101645
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1145 AM EST THU DEC 10 2009

.SYNOPSIS...
A STRONG STORM SYSTEM OVER SOUTHEAST CANADA WILL GRADUALLY PUSH
AWAY BY SATURDAY...ALLOWING HIGH PRESSURE TO BUILD INTO PENNSYLVANIA.
A WARM FRONT WILL PUSH THROUGH THE AREA SUNDAY...FOLLOWED BY A
COLD FRONT AROUND TUESDAY OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
MAIN LAKE ERIE SNOW BAND HAS PROPOGATED SLOWLY NORTHWARD THIS
MORNING...SIMILAR TO THE 4KM SPC WRF AND NAM12 SOLUTIONS.
ELSEWHERE...SYNOPTIC LIFT PROVIDED BY ELONGATED UPPER TROF
APPROACHING FROM THE OHIO VALLEY IS KEEPING SCATTERED FLURRIES
GOING ACROSS MUCH OF WESTERN AND CENTRAL PA...BUT LITTLE IF ANY
ACCUMULATION IS EXPECTED FROM THESE. HEADING INTO TONIGHT...THE
MAIN FORECAST CONCERN WILL BE THE EVOLUTION IN TIME OF THE MAIN
LAKE ERIE SNOWBAND...AND ITS SOUTHERN PROGRESS WITH RESPECT TO
NORTHERN WARREN AND MCKEAN COUNTIES LATE TONIGHT AND FRIDAY. AT
THIS TIME...ALL AVAILABLE DATA ARE NOT SUPPORTING THE SOUTHWARD
PROPOGATION OF THIS SNOWBAND DURING THE NEXT 12 TO 24 HOURS.

COLD AND BLUSTERY CONDITIONS TO CONTINUE THROUGH FRIDAY MORNING.
SOME WIND CHILLS MAY APPROACH ADVISORY CRITERIA LATER TONIGHT...
SO WILL TAKE A CLOSE LOOK AT THIS FOR THE AFTERNOON PACKAGE ISSUANCE.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
WSW BLYR FLOW SHOULD CONTINUE TO KEEP FOCUS OF LAKE EFFECT SNOW
NORTH OF THE BORDER FRIDAY...WHERE AN INTENSE SINGLE LES BAND
SHOULD BE AFFECTING WESTERN NY STATE. LATEST MESOSCALE BLYR
WIND/DIVERGENCE FIELDS INDICATE IT WILL BE A CLOSE CALL FOR
NW WARREN COUNTY...SO WILL HAVE TO MONITOR CLOSELY FOR POTENTIAL
+SN IN THAT AREA. 

FRIDAY SHOULD BE THE COLDEST DAY YET THIS SEASON...AS GEFS SHOWING
CORE OF COLD PASSING OVR PA WITH -2SD T0 -3SD ENS MEAN 850 TEMPS
OF ARND -18C. EVEN MIXING TO 850MB ONLY RESULTS IN HIGH TEMPS FROM
THE UTEENS NW MTNS...TO NR 30F LOWER SUSQ VALLEY. A CONTINUED
GUSTY WEST WIND WILL MAKE IT FEEL EVEN COLDER...WITH AFTN WIND
CHILLS HOLDING IN THE SINGLE DIGITS AND TEENS. BUFKIT SOUNDINGS
INDICATE FREQUENT GUSTS BTWN 30-35MPH ARE LIKELY. 

NAM12 OUTPUT SUGGESTS ENOUGH VEERING OF LOW LVL FLOW TO DRAW LAKE
EFFECT BAND SOUTHWARD INTO WARREN/MCKEAN COUNTIES. SNOW/WATER
RATIOS SHOULD BE QUITE HIGH...GIVEN FAVORABLE CONVERGENCE OF MAX
OMEGA WITHIN DGZ. HOWEVER...OVERALL SCENARIO IS FOR WEAKENING OF
LAKE EFFECT SNOW MACHINE FRI NITE...GIVEN APPROACH OF SFC RIDGE AND
ASSOCIATED LOWERING INVERSION HEIGHTS. WILL KEEP SNOW AMTS IN THE
1-2 INCH CATEGORY FRI NITE OVR NORTHERN WARREN/MCKEAN/POTTER
COUNTIES.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
SFC HI PRES PASSING SOUTH OF THE STATE SHOULD PROVIDE MOST THE
REGION WITH A MOSTLY SUNNY AND LESS WINDY SATURDAY. ALTHOUGH
LINGERING -SHSN/FLURRIES DO APPEAR LIKELY OVR THE N MTNS...ESP
EARLY. RETURN SW FLOW...COMBINED WITH THE SUNSHINE SHOULD ALLOW
TEMPS TO RECOVER TO NR SEASONAL READINGS. 

FAST MOVING SHORTWAVE APPROACHING FROM THE MIDWEST SHOULD AFFECT
OUR WX BY SUNDAY OR SUN NITE. BULK OF ENS MEMBERS INDICATE THIS
WILL BE A LIGHT PRECIP EVENT FOR CENTRAL PA AS WAA OVERSPREADS THE
AREA IN ADVANCE OF SHORTWAVE. ENSEMBLE PLUME DATA SUGGESTING MIXED
PTYPE WITH RAIN MOST LIKELY OVR THE SE AND SNOW/ICE MOST LIKELY
OVR THE N MTNS.

SHORTWAVE APPROACHING FROM THE N PLAINS WILL BRING NEXT CHC OF
WIDESPREAD PRECIP ARND TUESDAY OF NEXT WEEK. CURRENT GEFS/NAEFS
OUTPUT TRACKS SFC LOW WEST OF PA...INDICATING A BRIEF WARM
UP...FOLLOWED BY SHRASN WITH FROPA. FOR A DAY 7 FCST...FAIRLY GOOD
AGREEMENT AMONG MODELS OF A RETURN TO NW FLOW AND BLW NORMAL TEMPS
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
PERSISTENT CYC OVER-LAKE BLYR FLOW WILL KEEP MVFR/IFR RESTRICTIONS
AT BFD/JST THRU AT LEAST 11/00Z. LOWER END VFR CIGS /BASES 3-5KFT
AGL/ SHUD BE THE RULE ACROSS THE CENTRAL MTNS WITH VFR IN THE SE.
STRONG PRES GRAD BTWN DEPARTING LOW AND SFC HIGH BUILDING EWD FM
THE LWR MS VLY WILL RESULT IN GUSTY WLY SFC WNDS 25-35KTS THRU THE
PD. THIS WILL CREATE LLVL MECHANICAL TURB ON TAKE-OFF/FAP AND MAY
ALSO LEAD TO ISSUES RELATED TO CROSS-WINDS/RNWY CONFIGS. WINDS
WILL BEGIN TO RELAX INTO THE WKEND AS HIGH DRIFTS OFF THE SRN MID
ATLC COAST. MDL GUID SHOWS ANOTHER LOW DVLPG OFF THE ECOAST EARLY
NEXT WEEK...WHICH MAY IMPACT THE AREA BUT CONFIDENCE IS LOW BEYOND
SUNDAY.

OUTLOOK... 
FRI...MVFR WEST OCNL IFR IN SHSN PSBL. VFR CENTRAL/EAST.
SAT...BCMG VFR.
SUN/MON...RESTRICTIONS PSBL.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...FITZGERALD
NEAR TERM...DEVOIR/STEINBUGL
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD/BEACHLER
AVIATION...STEINBUGL