126  
FXUS61 KCTP 230008  
AFDCTP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE STATE COLLEGE PA  
708 PM EST SUN DEC 22 2024  
   
SYNOPSIS  
 
HIGH PRESSURE OVER ONTARIO CANADA JUST TO THE EAST OF GEORGIAN  
BAY WILL DRIFT TO THE EAST ACROSS THE ADIRONDACKS TONIGHT.  
 
A WEAK AREA OF LOW PRESSURE AT THE SURFACE AND ALOFT WILL TRACK  
NORTH OF THE STATE MONDAY NIGHT INTO EARLY CHRISTMAS EVE. A  
PAIR OF WEAKENING SHORTWAVES ARE LIKELY TO RIDE THE NORTHERN  
PERIPHERY OF A BUILDING RIDGE OVER PA THE SECOND HALF OF NEXT  
WEEK, AS A LARGE SURFACE HIGH REMAINS ANCHORED NORTH OF NEW  
ENGLAND.  
 
 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/  
 
RIDGE OF SFC HIGH PRESSURE OVER THE REGION THIS AFTERNOON AND  
TONIGHT WILL SUPPORT MAINLY CLEAR SKIES, LIGHT WIND AND VERY  
COLD TEMPS IN THE SINGLE DIGITS. DAYBREAK MONDAY MINS OF A FEW  
TO SEVERAL DEG F BELOW ZERO ARE LIKELY IN THE PERENNIAL COLD  
SPOTS UP NORTH.  
 
 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/  
 
A RETURN SOUTHEAST TO SOUTHERLY FLOW BEHIND THE DEPARTING  
SURFACE HIGH WILL HELP TEMPERATURES REBOUND SLIGHTLY ON MONDAY  
AS HIGH, THEN THICKENING MID CLOUDS STREAM IN FROM THE WEST AHEAD  
OF AN UPSTREAM SHORTWAVE OVER THE W GRT LKS. GEFS 2M TEMPS  
INDICATE MAX TEMPS WILL REMAIN SEVERAL DEGREES BELOW AVERAGE.  
 
THE SHORTWAVE AN ASSOCIATED WEAK SFC LOW IS PROGGED TO PASS  
JUST NORTH OF THE REGION MONDAY NIGHT INTO EARLY TUESDAY.  
 
THE STRONGEST FORCING WITH THIS FEATURE SHOULD REMAIN NORTH OF  
THE AREA AND MOISTURE RETURN ALONG THE ATTENDANT LOW LEVEL JET  
IS UNIMPRESSIVE. STILL, PERIODS OF WEAK UVVEL WILL PRODUCE AREAS  
OF LIGHT SNOW/SNOW SHOWERS LATE MONDAY/MONDAY NIGHT.  
 
A COATING OF SNOW IS LIKELY NEAR THE ALLEGHENY FRONT WHILE  
SLIGHTLY OVER ONE INCH IS POSSIBLE ACROSS THE NW MTNS AS SOME  
ADDED MOISTURE FROM LAKE ERIE IS INJECTED INTO THE REGION POST  
COLD FRONTAL EARLY CHRISTMAS EVE. THE SOUTHERN VALLEYS AND SUSQ  
REGION SHOULD SEE MAINLY FLURRIES DURING THIS PERIOD.  
 
MODEL SOUNDINGS INDICATE THERE IS SOME RISK FOR A BIT OF VERY  
LIGHT FREEZING RAIN OVER THE LOWER SUSQ VALLEY AROUND 12Z  
TUESDAY, BUT IT IS UNCERTAIN WHETHER MEASURABLE PRECIP EVEN  
REACHES THAT FAR SOUTH.  
 
THE BEST FORCING AND DEEPEST MOISTURE SHOULD HAVE PASSED PA BY  
LATE TUESDAY MORNING LIKELY LEAVING A FAIRLY EXTENSIVE DECK OF  
GENERALLY NON-PRECIPITATING STRATOCU.  
 
THIS RESIDUAL LOW LEVEL MOISTURE ASCENDING THE ALLEGHENIES  
COULD RESULT IN SPOTTY VERY LIGHT SNOW/DRIZZLE INTO THE  
AFTERNOON OVER THE WESTERN PART OF THE FORECAST AREA.  
 
DRY CONDITIONS WITH LIGHT WIND AND VARYING AMOUNTS OF STRATO CU  
AND CIRRUS WILL SUPPORT GOOD/COMFORTABLE FLIGHT CONDITIONS  
FOR SANTA'S PERIOD OF HEAVY WORKLOAD LATE TUESDAY NIGHT/EARLY  
WEDNESDAY WITH TEMPS RANGING THROUGH THE 20S.  
 
 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/  
 
ON THE LARGE-SCALE, THE AMPLIFIED, COLD EASTERN  
CANADIAN/NORTHEASTERN CONUS UPPER TROUGH DOMINATING AT THE  
PRESENT TIME SHOULD BE A THING OF THE PAST BY CHRISTMAS DAY, AS  
THIS FEATURE LIFTS OUT INTO THE NORTHERN ATLANTIC. IT WILL  
REPLACED BY BUILDING HEIGHTS AND A GENERALLY MORE ZONAL FLOW  
PATTERN ALOFT. THIS TRANSLATES INTO MORE SEASONABLE TEMPERATURES  
FOR LATE DECEMBER ACROSS PA, EVEN TRENDING ABOVE CLIMO TOWARDS  
NEXT WEEKEND.  
 
AS FOR THE SENSIBLE WEATHER, THERE IS INCREASING CONFIDENCE THAT  
SURFACE HIGH PRESSURE FROM SOUTHEASTERN CANADA DOWN INTO THE  
NORTHEASTERN U.S. WILL KEEP THE WEATHER DRY FOR THE COMMONWEALTH  
FROM CHRISTMAS DAY INTO AT LEAST THURSDAY.  
 
UNCERTAINTY GROWS LATER IN THE WEEK, AS LOW-LEVEL EASTERLY FLOW  
AND THE APPROACH OF WEAK SHORT-WAVE ENERGY FROM THE MIDWEST  
COULD BRING BOUTS OF LIGHT PRECIPITATION, ESPECIALLY FOR  
SOUTHERN AND WESTERN SECTIONS OF THE STATE. AT THIS EARLY  
JUNCTURE, LIGHT RAIN APPEARS TO BE THE MOST PROBABLE  
PRECIPITATION TYPE, BUT POCKETS OF LIGHT WINTRY MIX ARE NOT BY  
ANY MEANS OFF THE TABLE.  
 
 
   
AVIATION /00Z MONDAY THROUGH FRIDAY/  
 
VFR (MAINLY SKC) EXPECTED AT ALL TAF SITES THROUGH TONIGHT AND  
LIKELY ALL OF THE DAYLIGHT HOURS MONDAY AS WELL AS A RIDGE OF  
HIGH PRESSURE EXTENDING SOUTH ACROSS CENTRAL PA SLIDES SLOWLY TO  
THE EAST.  
 
A THICKENING LAYER OF MID LEVEL CLOUDS AOA 10KFT AGL WILL DRIFT  
OVER THE REGION LATER MONDAY MORNING AND MON AFTERNOON.  
 
CLOUD BASES WILL LOWER MONDAY NIGHT (ESP ACROSS THE NORTHERN  
AND WESTERN MOUNTAINS OF PA) WITH SOME PERIODS OF LIGHT  
SNOW/SNOW SHOWERS DEVELOPING.  
 
OUTLOOK...  
 
MON...NO SIG WX.  
 
TUE...LIGHT SNOW ENTERS W PA MONDAY EVENING AND OVERSPREADS THE  
REST OF THE AREA OVERNIGHT MONDAY NIGHT/EARLY TUESDAY. MVFR CIGS  
AND VSBYS FOCUSED OVER KJST AND KBFD.  
 
WED...NO SIG WX.  
 
WED NIGHT...PATCHY LIGHT FREEZING RAIN POSSIBLE.  
 
THU...LIGHT RAIN POSSIBLE SOUTH.  
 
FRI...NO SIG WX.  
 
 
   
CTP WATCHES/WARNINGS/ADVISORIES  
 
NONE.  
 
 
 
 
 
SYNOPSIS...LAMBERT/FITZGERALD  
NEAR TERM...LAMBERT/FITZGERALD  
SHORT TERM...LAMBERT/FITZGERALD  
LONG TERM...JUREWICZ/COLBERT  
AVIATION...LAMBERT/GARTNER  
CLICK HERE TO GO TO PREVIOUS BULLETINS.
The Nexlab PA Page
Main Text Page