102
FXUS61 KCTP 221234
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
734 AM EST WED JAN 22 2025
SYNOPSIS
A RIDGE OF HIGH PRESSURE EXTENDING ALONG THE ENTIRE LENGTH OF
THE APPALACHIANS WILL BRING THE COLDEST TEMPERATURES OF THIS
CURRENT ARCTIC OUTBREAK ACROSS THE REGION THIS MORNING. THIS
RIDGE WILL DRIFT EAST AND OFF THE MID ATLANTIC COAST TONIGHT
INTO THURSDAY. UPPER LEVEL TROUGHING WILL REMAIN OVER THE AREA
INTO EARLY NEXT WEEK WITH A SERIES OF WEAK SHORTWAVES PASSING
THROUGH WITH JUST SOME FLURRIES OR A FEW BRIEF SNOW SHOWERS.
NEAR TERM /UNTIL 6 PM THIS EVENING/
BITTER COLD TEMPERATURES IN THE SINGLE DIGITS TO LOW TEENS
(BELOW ZERO) AND BONE DRY PWATS OF LESS THAN ONE TENTH OF AN
INCH COVERED CENTRAL PA THIS MORNING WITH A RIDGE OF 1030+ MB
SFC HIGH PRESSURE CENTERED OVER THE COMMONWEALTH.
SKIES WERE MAINLY CLEAR WITH LIGHT AND VARIABLE WIND.
LOCATIONS THAT HAD THE WIND GO CALM SAW READINGS OF -10 TO -20F
WITH THE WINNER AT MINUS 20F BEING LOPEZ IN SULLIVAN COUNTY
(WHICH SO HAPPENS TO BE THE BIRTHPLACE OF MY MATERNAL
GRANDMOTHER). I RECALL MANY STORIES FROM HER ABOUT THE COLD
THERE IN THAT HIGH RURAL VALLEY. YES, SHE WALKED IN KNEE TO
WAIST DEEP SNOW (UPHILL BOTH WAYS) TO THE SMALL SCHOOL SHE
ATTENDED.
THE SUNSHINE AND LIGHT WIND WILL TAKE SOME OF THE BITE OUT OF
THE AIR AS TEMPS SLOWLY RISE TO THE UPPER SINGLE DIGITS TO MID
TEENS FOR AFTERNOON HIGHS.
THE LEADING EDGE OF AN EXTENSIVE DECK OF ALTO CU CLOUDS,
CURRENTLY EXTENDING FROM KGRR TO KIND WILL BE MOVING EAST AT
AROUND 40 KTS AND REACH THE NW MTNS AND LAUREL HIGHLANDS EARLY
THIS AFTERNOON, AND DURING THE MID TO LATE AFTERNOON ACROSS THE
CENTRAL MTNS AND SUSQ VALLEY. CLOUD BASES WILL REMAIN AOA 7 KFT
AGL WITH NOTHING MORE THAN A FEW FLURRIES OVER THE RIDGE TOPS OF
WESTERN PA.
SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/
MODEL RH PROFILES INDICATE VARIABLE AMOUNTS OF WARM
ADVECTION/MID LEVEL CLOUDS AROUND TONIGHT WITH A LIGHT SOUTHERLY
BREEZE, THAT WILL LIMIT THE TEMP DROP RELATIVE TO THE PAST FEW
NIGHTS.
MINS WILL DIP BELOW ZERO IN SOME RURAL LOCATIONS, BUT WILL
GENERALLY BE IN THE SINGLE DIGITS.
AS PREVIOUSLY NOTED, THE WEAKEST LLVL P-GRADIENT AND BEST
RADIATIONAL COOLING SHOULD BE OVER SOUTHEAST PA, CLOSEST TO THE
RETREATING SURFACE RIDGE. THE RESULT SHOULD BE FAIRLY UNIFORM
MIN TEMPS IN THE SINGLE DIGITS ABOVE ZERO.
MARKEDLY LESS COLD CONDITIONS ARE ANTICIPATED THURSDAY, AS A
SOUTHWEST FLOW DEVELOPS BETWEEN HIGH PRESSURE OFF OF THE EAST
COAST AND AN UPSTREAM COLD FRONT OVER THE GRT LKS. SEE NO REASON
TO DEVIATE FROM NBM MAX TEMPS, WHICH ARE IN THE 20S. RH
TIMESECTIONS SUPPORT CLOUDS ARRIVING FROM WEST TO EAST DURING
THE AFTERNOON AHEAD OF THE APPROACHING COLD FRONT. MODEL
SOUNDINGS INDICATE THE RETURN MOISTURE AHEAD OF THE FRONT WILL
BE SHALLOW, BUT COULD SUPPORT SOME OCCASIONAL LIGHT SNOW WHERE
THE SSW FLOW IS FORCED TO ASCEND THE NW MTNS LATE IN THE DAY
THROUGH MUCH OF FRIDAY.
IN FACT, THE CLOUD LAYER (INITIALLY UP TO 7-8 KFT AGL THURSDAY
AFTERNOON AND EVENING THEN ONLY UP TO 3-4 KFT AGL ON FRIDAY)
WILL BE OCCUPIED BY THE ENTIRE DGZ. PERFECT CONDITIONS FOR THE
OROGRAPHIC LIGHT SNOW. INCLUDED A 36 HOUR SNOW TOTAL GRID (12Z
THURSDAY THROUGH 00Z SAT) TO CAPTURE THE BULK OF THIS MINOR
WINTER PRECIP EVENT OVER THE WESTERN MTNS.
OUTSIDE OF THIS MINOR SNOWFALL, EXPECT MAINLY DRY AND COLD
CONDITIONS INTO THE WEEKEND. TOWARDS THE END OF THIS WEEK A WEAK
UPPER LEVEL SHORT WAVE WILL SWING OFF THE GREAT LAKES. A
SURFACE TROUGH WILL ARRIVE BY FRIDAY MORNING, BRINGING WITH IT
ANOTHER MOISTURE STARVED COLD FRONT. DESPITE THE SYNOPTIC
FORCING THERE WILL NOT BE ENOUGH MOISTURE TO ALLOW FOR MUCH
PRECIPITATION. EVEN WIND FLOW WILL REMAIN MOSTLY WESTERLY BEHIND
THIS FRONT MAKING LAKE EFFECT SNOW IN THE NORTHWEST UNLIKELY AT
THE BEGINNING OF THE EXTENDED PERIOD. STILL ENOUGH OF A CHANCE
TO ENTER SLIGHT CHANCE POPS ACROSS THE HIGHER TERRAIN.
LONG TERM /SATURDAY THROUGH TUESDAY/
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 WEAK SHORTWAVE PASSAGES
EARLY SUNDAY AND AGAIN ON MONDAY WILL BRING THE CHANCE OF A FEW
SNOW SHOWERS OVER THE NW MTNS, FOLLOWED BY LAKE-ENHANCED
OROGRAPHIC SNOW SHOWERS OVER THE ALLEGHENIES. HOWEVER, A
LARGELY FROZEN LK ERIE SHOULD RESULT IN MINIMAL ACCUMULATIONS.
A MINORITY OF ENSEMBLE MEMBERS ARE A BIT DEEPER WITH THE MONDAY
SHORTWAVE, 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, THE BULK OF GUIDANCE CURRENTLY
SUPPORTS DRY WEATHER.
AVIATION /13Z WEDNESDAY THROUGH SUNDAY/
HIGH CONFIDENCE IN WIDESPREAD VFR FLYING THROUGH THE 22/12Z TAF
PERIOD.
OUTLOOK...
THU...VFR THEN MVFR/IFR POSSIBLE THURSDAY NIGHT WITH -SHSN IN
NORTHERN AND WESTERN PA.
FRI...MVFR/IFR CONDITIONS POSSIBLE WITH -SHSN IN NORTHERN &
WESTERN PA MAINLY DURING THE DAY.
SAT...VFR/NO SIG WX.
SUN...MVFR IN -SHSN POSSIBLE IN NORTHERN & WESTERN PA.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES FOR JANUARY 22:
HARRISBURG 14F IN 2014
WILLIAMSPORT 14F IN 1961
ALTOONA 10F IN 2014
BRADFORD 6F IN 2014
STATE COLLEGE 7F IN 1936
CTP WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY UNTIL NOON EST TODAY FOR PAZ004>006-
010>012-017>019-025>028-034>037-041-042-045-046-049>053-
056>059-063>066.
EXTREME COLD WARNING UNTIL NOON EST TODAY FOR PAZ024-033.
SYNOPSIS...LAMBERT/FITZGERALD
NEAR TERM...LAMBERT/FITZGERALD
SHORT TERM...GUSEMAN/LAMBERT/FITZGERALD
LONG TERM...FITZGERALD
AVIATION...STEINBUGL
CLIMATE...STEINBUGL
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