004
FXUS61 KCTP 231046
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
546 AM EST THU JAN 23 2025
SYNOPSIS
*A WEAK CLIPPER TRACKING NORTH OF PA WILL BRING VARIABLE AMOUNTS
OF MAINLY MID CLOUDS TO THE COMMONWEALTH FOR MUCH OF TODAY.
*LAKE EFFECT AND UPSLOPE SNOW SHOWERS WILL DEVELOP LATE TODAY
AND CONTINUE INTO FRIDAY ACROSS THE NORTHWEST MOUNTAINS AND
LAUREL HIGHLANDS, BRINGING GENERALLY LIGHT ACCUMULATIONS.
*TEMPERATURES WILL TREND UPWARD TOWARD MORE NORMAL LATE JANUARY
VALUES THIS WEEKEND AND INTO THE BEGINNING OF NEXT WEEK.
NEAR TERM /UNTIL 7 AM THIS MORNING/
SOUTH TO SOUTHWESTERLY FLOW RESPECTIVELY AT THE SURFACE AND
ALOFT WILL OCCUR ACROSS THE REGION TODAY AHEAD OF A WEAK COLD
FRONT, THAT WAS CURRENTLY MOVING THROUGH THE CHICAGO AREA.
MODEL GUIDANCE CONTINUES TO PROJECT MOSTLY SUNNY SKIES FOR MUCH
OF CENTRAL PA THURSDAY, AS THE STRONGEST MID LEVEL WARM
ADVECTION LIFTS NORTH OF THE PA/NY BORDER.
LITTLE OR NO PRECIP WILL REACH THE GROUND DURING THE DAYLIGHT
HOURS TODAY FROM VARIABLE AMOUNTS OF MID-LEVEL/ALTOCU CLOUDS
ACROSS MAINLY NORTHERN PA - BASED AOA 7000 FT AGL.
THE LIGHT WIND SPEEDS THIS MORNING WILL FRESHEN INTO THE 7-10KT
RANGE ACROSS THE NW HALF OF THE STATE, THAT WILL RESIDE WITHIN
THE MODERATE LLVL P-GRADIENT. GUSTS INTO THE TEENS ARE EXPECTED
TO PUT A BITE INTO THE OTHERWISE MODERATING AIRMASS WITH TEMPS
RANGING THROUGH THE 20S FOR AFTERNOON HIGHS. A FEW VALLEY
LOCATIONS IN SCENT PA (WHERE THE MOST SUNSHINE WILL BE FOUND
TODAY) WILL LIKELY REACH OR SLIGHTLY ECLIPSE THE 30 DEGREE MARK.
SHORT TERM /7 AM THIS MORNING THROUGH FRIDAY NIGHT/
MODEL SOUNDINGS INDICATE THE RETURN MOISTURE AHEAD OF THE FRONT
WILL BE SHALLOW, BUT RIGHT WITHIN THE FAVORABLE THERMAL RIBBON
FOR DENDRITIC SNOW GROWTH, WHICH SHOULD LEAD TO OCCASIONAL
LIGHT SNOW WHERE THE WSW FLOW IS FORCED TO ASCEND THE ALLEGHENY
PLATEAU THIS EVENING AND TONIGHT.
LARGE SCALE SUBSIDENCE BEHIND THE EXITING COLD FRONT SHOULD
RESULT IN MAINLY DRY CONDITIONS ELSEWHERE ACROSS CENTRAL PA
TONIGHT AND FRIDAY.
HOWEVER, VEERING BOUNDARY LAYER FLOW SHOULD RESULT IN SCATTERED
LAKE EFFECT SNOW SHOWERS MOVING OVER THE NW MTNS. LOW INVERSION
HEIGHTS AND A MAINLY FROZEN LK ERIE SHOULD KEEP ACCUMULATIONS
MINIMAL.
MODEL QPF SUPPORTS 24 TO 30 HOUR TOTAL SNOWFALL FROM THIS
AFTERNOON THROUGH THROUGH FRIDAY RANGING FROM A DUSTING OVER
MOST OF THE ALLEGHENY PLATEAU, TO 1 INCH ON THE RIDGES WEST OF
RT 219 IN THE LAUREL HIGHLANDS AND PERHAPS UP TO 2 INCHES IN
THE HEART OF THE SNOWBELT IN NORTHWEST WARREN COUNTY.
ANY SNOW SHOWERS SHOULD END FRIDAY NIGHT, AS SURFACE RIDGING
BUILDS INTO THE STATE AND BOUNDARY LAYER FLOW SHIFTS TO THE
SOUTHWEST.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
MEDIUM RANGE GUIDANCE SUPPORTS MAINLY DRY AND SEASONABLY COLD
WEATHER THIS WEEKEND INTO EARLY NEXT WEEK, AS UPPER LEVEL
TROUGHING REMAINS OVER THE REGION DESPITE THE DEPARTURE OF THE
ANOMALOUS COLD. THE 18Z EPS INDICATES A SERIES OF WEAK,
MOISTURE-STARVED SHORTWAVES WILL TRAVERSE THE REGION IN THE
NORTHWEST FLOW. THE PASSAGE OF EACH OF THESE SYSTEMS WILL BRING
THE CHANCE OF A BIT OF VERY LIGHT SNOW OVER THE NW MTNS,
FOLLOWED BY SCATTERED LAKE-ENHANCED OROGRAPHIC SNOW SHOWERS OVER
THE ALLEGHENIES. HOWEVER, A LARGELY FROZEN LK ERIE SHOULD
RESULT IN MINIMAL ACCUMULATIONS.
A FEW ENSEMBLE MEMBERS ARE A BIT DEEPER WITH A PAIR OF
SHORTWAVES EARLY NEXT WEEK, RESULTING IN A WAVE OF LOW PRESSURE
PASSING SOUTH OF PA. THIS SCENARIO WOULD RESULT IN A PERIOD OF
SNOW OVER PRIMARILY SOUTHERN PA. HOWEVER, THIS APPEARS A LOW
PROBABILITY, WITH THE BULK OF GUIDANCE CURRENTLY SUPPORTING DRY
WEATHER OUTSIDE OF SOME VERY LIGHT LAKE-ENHANCED OROGRAPHIC SNOW
OVER THE N AND W MTNS.
AVIATION /10Z THURSDAY THROUGH MONDAY/
VFR CONDITIONS ARE EXPECTED TO CONTINUE OVERNIGHT AND THROUGH
THE DAY THURSDAY. MID AND HIGH CLOUDS WILL INCREASE IN COVERAGE
WEST TO EAST AS WARM ADVECTION INCREASES AHEAD OF A MOISTURE-
STARVED DISTURBANCE APPROACHING FROM THE WEST. MODEL SOUNDINGS
SUGGEST THAT MUCH OF THIS CLOUD COVER WILL DISSIPATE DURING THE
DAY ON THURSDAY AND PARTLY CLOUDY TO MAINLY CLEAR SKIES ARE
EXPECTED AFTER 12Z.
WINDS WILL SHIFT TO THE WEST-SOUTHWEST THURSDAY AFTERNOON WHICH
WILL LEAD TO CLOUDS DEVELOPING AT BFD AND JST. MOISTURE WILL BE
VERY LIMITED, AT LEAST INITIALLY, SO NOT EXPECTING ANY SNOW
SHOWERS PRIOR TO 18Z. MODEL RH PROFILES DO SUGGEST THAT LOWER
CEILINGS DEVELOP DURING THE LATE AFTERNOON AND A FEW LAKE EFFECT
AND UPSLOPE SNOW SHOWERS COULD LEAD TO VISIBILITY RESTRICTIONS
AT BFD AND JST INTO THE EVENING. A MENTION OF PROB30 SNOW
SHOWERS HAS BEEN INCLUDED FOR BFD BETWEEN 19Z AND 21Z WITH
LIGHT SNOW AND LOWER CEILINGS LIKELY TOWARDS THE END OF THIS
FORECAST PERIOD.
OUTLOOK...
THU NIGHT...RESTRICTIONS POSSIBLE AT BFD AND JST WITH -SHSN.
FRI...MVFR/IFR CONDITIONS POSSIBLE WITH -SHSN IN NORTHERN &
WESTERN PA MAINLY DURING THE DAY.
SAT...VFR/NO SIG WX.
SUN-MON...MVFR IN -SHSN POSSIBLE IN NORTHERN & WESTERN PA.
CLIMATE
A RECORD LOW TEMPERATURE OF -11 DEGREES WAS SET AT ALTOONA, PA
EARLY WEDNESDAY MORNING. THE OLD RECORD WAS -5 DEGREES SET IN
1984.
A RECORD LOW TEMPERATURE OF -11 DEGREES WAS ALSO SET AT
JOHNSTOWN, PA EARLY WEDNESDAY MORNING. THE OLD RECORD WAS -9
DEGREES SET IN 1984.
A RECORD LOW TEMPERATURE OF -18 DEGREES WAS TIED AT BRADFORD,
PA EARLY WEDNESDAY MORNING. THE PREVIOUS RECORD LOW TEMPERATURE
DATE WAS 2022.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...LAMBERT/NPB
NEAR TERM...LAMBERT/FITZGERALD
SHORT TERM...LAMBERT/FITZGERALD/NPB
LONG TERM...LAMBERT/FITZGERALD
AVIATION...GARTNER/BOWEN
CLIMATE...STEINBUGL/LAMBERT
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