FXUS61 KCTP 221132
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
632 AM EST TUE DEC 22 2009

.SYNOPSIS...
AN UPPER LEVEL LOW WILL PASS TO THE NORTH OF THE STATE TODAY AND
WEDNESDAY. THIS LOW PRESSURE WILL KEEP THE REGION COLD WITH
CLOUDS AND FLURRIES ACROSS THE NORTH AND WEST. HIGH PRESSURE
BUILDS IN FOR A BRIEF TIME LATE WEDNESDAY AND THURSDAY. A STRONG
LOW PRESSURE SYSTEM OVER THE MIDWEST WILL PROBABLY PRODUCE SOME
WINTRY PRECIPITATION CHRISTMAS MORNING...BUT IT SHOULD TURN TO A
COLD RAIN THROUGH CHRISTMAS DAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS SOLID OVER THE ENTIRE AREA EARLY THIS MORNING...BUT THE
FLOW BECOMES LESS CYCLONIC BY LATE IN THE DAY. UNTIL THEN...THE
SNOW SHOWERS AND FLURRIES DOWN WIND OF THE LAKE WILL CONTINUE.
HOWEVER...THE RELATIVELY HIGH BASES TO THE CLOUDS WILL KEEP MOST
AREAS FROM GETTING ANY ACCUMULATING SNOW. JUST A DUSTING IS
POSSIBLE THROUGH 10 AM. BREAKS WILL APPEAR IN THE CLOUDS. TEMPS
MAY NOT CLIMB MORE THAN 6 OR 8F THRU THE DAY...DUE TO 8H TEMPS
DROPPING SLIGHTLY AND THE PERSISTENT CLOUD DECK.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
LOWERING INVERSION FINALLY GETS NEAR THE SFC...THERMAL TROF
PASSES TO THE EAST AND LLVL FLOW BECOMES DIFFLUENT AS HIGH
PRESSURE BEGINS TO BUILD IN THIS EVENING. THIS WILL HELP TO BREAK
UP THE LOW CLOUDS...EXCEPT IN THE FAR NORTH WHERE THE BREAKS MAY
ONLY BE BRIEF. THE FLOW IS STILL NORTHERLY AND COULD BRING
ADDITIONAL/RENEWED CLOUDS IN FM LK ONT. EXPECT SOME SINGLE DIGIT
READINGS ACROSS THE AREA WITH SNOWPACK ON GROUND. WITH SUCH A
CHILLY START...TEMPS MAY NOT GET BACK UP TO FREEZING ANYWHERE IN
THE CWFA WED.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
A WINTRY MIX POSSIBLE FOR CHRISTMAS EVE...

CONFIDENCE REMAINS HIGH WITH REGARDS TO A PERIOD OF WINTRY
PRECIPITATION AFFECTING CENTRAL PENN LATE CHRISTMAS EVE...WITH A
HIGH PROBABILITY OF A CHANGE TO PLAIN RAIN ON CHRISTMAS DAY. THIS
WILL UNDOUBTEDLY HAVE NEGATIVE IMPACTS ON HOLIDAY TRAVEL. TIMING
OF THE ONSET AND HEAVIEST PRECIPITATION IS COMING INTO BETTER
FOCUS BASED ON THE LATEST COMPUTER GUIDANCE. BUT...AS IS TYPICALLY
THE CASE...THE DETAILS OF FCST SUCH AS PRECIPITATION TYPE/LOCATION
REMAIN ELUSIVE AT THIS RANGE. 

ALL MDL SOLNS ARE PORTRAYING A SLOWER...WWD TREND IN SFC LOW
POSITION AS IT EJECTS NNEWD FM THE SRN PLAINS THUR NGT INTO FRI.
THE WRN TRACK SUGGESTS COLD AIR DAMMING E OF THE APPLCHNS WILL BE
MORE PREVALENT...AS STG HI PRES RETREATS INTO NRN NEW ENG/QUE.

MUCH COLDER AIR WILL MOVE INTO THE REGION LATE THIS WEEKEND AND
EARLY NEXT WEEK AS A MEAN TROUGH TAKES HOLD OVER MUCH OF THE ERN
U.S. CYC FLOW WILL KEEP SCT LES SHWRS OVER THE WESTERN AND NORTHERN
MNTS. BLEND OF EC/GFS MEAN HEIGHTS SHOWS THE LW TROUGH LIFTING OUT
AS THE FLOW BECOMES MORE ZONAL INTO EARLY NEXT WEEK.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
FRONT SEPERATING VERY COLD AIR NORTH OF THE LAKES FROM MILDER AIR
ACROSS SOUTHERN PA WILL KEEP CONSIDERABLE CLDS AND A FEW LIGHT
SNOW SHOWERS ACROSS THE AREA TODAY. THIS WILL BE ESPECIALLY THE 
CASE THIS MORNING. CONDITIONS WILL RANGE FROM MVFR AND IFR ACROSS
THE MTS...MVFR AND VFR AT AOO AND UNV...TO VFR AT IPT AND MDT. AT
THE SAME TIME...AN UPPER LVL LOW WILL BE ACROSS NEW ENGLAND...WITH
MORE CLDS. AT TIMES...PA MAY GET A BREAK WITH THE CLDS TODAY AND
WED. AT THIS POINT...MODELS ARE SLOWER WITH THE NEXT SYSTEM...SO
THU MAY NOT BE BAD...AS IT WAS LOOKING THE OTHER DAY.

LOOKS LIKE SOME RAIN FOR CHRISTMAS. COULD START AS A MIX.
COOLER FOR THE WEEKEND...BUT NOT REAL COLD. A LOT OF DIRECTIONAL
SHEAR...SO LAKE EFFECT NOT LIKELY EITHER.

OUTLOOK... 
WED...MAINLY VFR BUT STILL POCKETS OF MVFR AND IFR ACROSS THE
REGION.
THU...VFR.
FRI...FREEZING PRECIPITATION PSBL EARLY...WITH MVFR AND IFR 
CONDITIONS POSSIBLE. 
SAT...IFR/MVFR CONDITIONS CONDS PSBL EARLY.

&&

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

&&

$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...DANGELO/STEINBUGL
AVIATION...FITZGERALD/MARTIN