FXUS61 KCTP 230004
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
704 PM EST TUE DEC 22 2009
.SYNOPSIS...
AN UPPER LEVEL LOW WILL PASS TO THE NORTH OF THE STATE TONIGHT AND
WEDNESDAY...KEEPING THE REGION COLD WITH CLOUDS AND FLURRIES. HIGH
PRESSURE WILL BRIEFLY BUILD INTO THE AREA WEDNESDAY AND DEPART ON
THURSDAY. A STRONG LOW PRESSURE SYSTEM OVER THE MIDWEST WILL BRING
WINTRY PRECIPITATION FOR CHRISTMAS DAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
WEAK FRONT PUSHING ACROSS THE REGION THIS AFTERNOON WILL CONTINUE
TO PRODUCE SCATTERED LIGHT SNOW SHOWERS/FLURRIES MAINLY ALONG WIND
SHIFT LINE. WOULDN/T EXPECT ANY MORE THAN A COATING IN SOME
SPOTS. BEHIND THIS FEATURE SKIES WILL BECOME MOSTLY CLEAR. CENTER
OF LOW PRESSURE AREA SLIDES ACROSS NY STATE OVERNIGHT INTO
WED...AND WILL PUSH CLOUDS BACK INTO THE NORTH OVERNIGHT ALONG WITH
JUST A CHANCE FOR LIGHT SNOW SHOWERS MAINLY WED. EXPECT SOME
SINGLE DIGIT READINGS ACROSS THE AREA WITH SNOWPACK ON
GROUND...THOUGH MOST LOCATIONS WILL BE IN THE TEENS. WITH A
CHILLY START...TEMPS MAY NOT GET BACK UP TO FREEZING ANYWHERE IN
THE CWA WED.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
LOW PRESSURE SLIDING ACROSS NY STATE WILL BE THE MAIN FEATURE THIS
PERIOD AS COLDER AIR BEHIND THIS WILL PUSH INTO PA WED IN WED
NIGHT. PROXIMITY WILL ALSO BRING A CHANCE OF SNOW SHOWERS TO
NORTHERN TIER ON WED.
HIGH PRESSURE RIDGE BUILDS IN FROM THE NORTH WED NIGHT. WITH
CLEARING SKIES...TEMPS SHOULD BE CLOSE TO WED/S LOWS IN THE TEENS
WITH SOME SINGLE DIGITS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
WINTRY PRECIPITATION FOR THE CHRISTMAS HOLIDAY...
PHASING OF TWO DISTINCT NRN AND SRN STREAM SHRT/WVS WILL RESULT IN
A MAJOR STORM SYSTEM DEVELOPING OVR THE CENTRAL STATES THUR NGT
INTO FRIDAY. A DEEPER...MORE AMPLIFIED SOLN ALOFT RESULTS IN A SFC
LOW TRACK TO THE N/W OF YESTERDAYS CONSENSUS...FM THE LWR MS VLY
TO IA BY 25/12Z. THIS TRACK CONTINUES TO SUPPORT A STUBBORN COLD
AIR DAMMING SCENARIO OVR CENTRAL PENN...AS ALL MDL GUID SHOWS A
WELL-DEFINED PRESSURE CHANNELED SFC RIDGE REMAINING WEDGED EAST OF
THE APPLCHNS. THE MODELS ARE ALSO IN AGREEMENT WITH A SECONDARY
WAVE DEVELOPING INVOF THE VA TIDEWATER BY 26/12Z...LIFTING NEWD
ALONG THE MID ATLANTIC AND SRN ENG COASTS THRU THE DAY ON SAT.
THE MAIN SOURCES OF UNCERTAINTY CONTINUE TO BE TIMING AND PTYPE.
THESE VARIABLES GO HAND-IN-HAND AS TIMING WILL GREATLY INFLUENCE
PTYPE. WHILE A SLOWER EWD PROGRESSION OF THE PCPN SHIELD REMAINS
THE TREND BASED ON A MORE DEEP-LAYERED CLOSED LOW ALOFT AND NWD SFC
LOW POSITION...STRONG WARM AIR ADVECTION AHEAD OF THE TRAILING
COLD FRONT SWEEPING EWD THRU THE MID-SOUTH ARGUES FOR KEEPING
MANUAL GRIDDED POPS/QPF ON THE ERN EDGE OF THE GUID ENVELOPE.
THERMAL PROFILES REMAIN PROBLEMATIC RIGHT THROUGH CHRISTMAS
DAY...AND WILL RELY HEAVILY ON THE SREF MEAN WHICH HAS FZRA AS
THE DOMINANT PTYPE. HOWEVER BASED ON EVAP COOLING/WETBULBS (AND
POSSIBLE EARLIER ARRIVAL OF PCPN) WILL ALSO MENTION CHC OF SN/IP.
COLDER AIR WILL BLAST INTO THE AREA FROM THE WEST SAT NGT...LKLY
CHANGING ANY PCPN OVER TO SNOW/SHWRS. THE SHARP GRADIENTS AND LLVL
WIND FIELDS COULD MAKE FOR STRONG WINDS NEAR COLD/OCCLD FNT. A
MEAN UPPER TROUGH TAKES HOLD OVER MUCH OF THE ERN U.S. INTO EARLY
NEXT WEEK WITH CYC FLOW KEEPING SCT LES SHWRS OVER THE WESTERN AND
NORTHERN MNTS. AN UNSETTLED PATTERN MAY UNFOLD TWD THE NEW YEAR AS
IT APPEARS THE SRN STREAM WILL REMAIN ACTIVE.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
VFR CIGS WILL PERSIST THRU 06Z FOR MOST AIRFIELDS...EXCEPT
JST/AOO WHERE CIGS HAVE HOVERED ARND IFR/MVFR. EXPECT MORE PERIODS
OF IFR/MVFR THAN VFR FOR JST/AOO THUS HAVE HELD ONTO LOW
CIGS...WITH DECREASING CIGS AT UNV. LLVL FLOW REMAINS
NWSTRLY...TRYING TO TURN NORTHERLY ARND 13Z WED. THIS POSES A
CONCERN AS SOME GUIDANCE SUGGESTS IFR/MVFR CIGS SLIDING SOUTH INTO
IPT/BFD. MOISTURE WILL REMAIN SHALLOW FOR MOST AIRFIELDS...THUS
PSBLY ALLOWING IFR/MVFR CIGS TO LINGER WITH MINIMAL MIXING THRU
MUCH OF WED. A FEW ISO SHSN COULD PUSH INTO BFD MIDDAY...HOWEVER
CONFIDENCE IS LOW ATTM.
OUTLOOK...
THU...VFR WITH POCKETS OF MVFR/IFR ACROSS ALLEGHENIES.
FRI...POOR FLYING CONDS. WIDESPREAD IFR TEMPO LIFR WEST/CENTRAL.
MVFR EAST. FZRA/SN EARLY THEN RA. LINGERING FZRA EAST TURNING RA
LATE.
SAT...MVFR/SCT IFR. SHSN WEST.
SUN...MVFR/IFR WEST W/SHSN. PATCHY VFR/MVFR EAST.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/RXR
NEAR TERM...RXR
SHORT TERM...RXR
LONG TERM...STEINBUGL
AVIATION...BEACHLER
