122
FXUS61 KCTP 200755
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
355 AM EDT TUE OCT 20 2026
WHAT HAS CHANGED
* NO CHANGES
KEY MESSAGES
1) AN EXTENDED STRETCH OF DRY AND SEASONABLE WEATHER CONTINUES
THROUGH THE REST OF THIS WEEK
DISCUSSION
KEY MESSAGE 1: AN EXTENDED STRETCH OF DRY AND SEASONABLE WEATHER
CONTINUES THROUGH THE REST OF THIS WEEK
330 AM UPDATE...
SURFACE TEMP/DEWPOINT SPREADS OF A FEW TO SEVERAL DEGREES WERE
HELPING TO GREATLY MINIMIZE THE DEVELOPMENT OF VALLEY FOG SO FAR
EARLY TODAY.
ASIDE FROM AN ILL-DEFINED, WEAK COLD FRONT MOVING SE FROM THE
LOWER GLAKES REGION WITH NOTHING MORE THAN SOME SHALLOW SCT-BKN
STRATO CU (TOPPED BY SOME AREAS OF THIN CIRRUS) ACROSS THE NW
MTNS DURING THE SECOND HALF OF THIS MORNING, SKIES WILL STAY
CLEAR UNDER PERSISTENT HIGH PRESSURE OVER THE NORTHEAST U.S.
THIS DOMINANT WEATHER FEATURE WILL CONTINUE OUR STRETCH OF DRY
WEATHER WITH SEASONABLE TEMPERATURES FOR THE REST OF THIS WEEK.
TEMPERATURES TO START THE DAY TODAY WILL RANGE FROM NEAR 30
DEGREES THROUGHOUT THE PERENNIAL COLD SPOTS IN CENTRAL AND
NORTHERN PA TO THE MID 30S AND LOWER 40S IN THE SOUTH.
PATCHY FROST WILL BE POSSIBLE IN THE COLDEST SPOTS ACROSS THE
LOWER SUSQUEHANNA VALLEY WHERE LANCASTER AND LEBANON COUNTIES
ARE STILL HANGING ONTO THE GROWING SEASON BASED ON THE ABSENCE
OF WIDESPREAD SUB-FREEZING TEMPS SO FAR.
HIGH TEMPERATURES WILL PEAK TODAY IN MOST PLACES WITH MID
AFTERNOON READINGS RANGING FROM THE LOW 60S ACROSS THE HIGHEST
TERRAIN IN NORTHERN PA TO NEAR 70 DEGREES IN SOME OF THE
SOUTHERN VALLEYS
LATEST MEDIUM RANGE MODEL GUIDANCE INDICATES THAT THE DRY SPELL
WILL CONTINUE INTO THE FINAL WEEK OF OCTOBER. THIS RAIN- FREE
PATTERN WILL BE HIGHLIGHTED BY A STRING OF SUNNY AND SEASONABLY
WARM AFTERNOONS WITH LOW HUMIDITY FOLLOWED BY CLEAR AND CHILLY
MOONLIT NIGHTS WITH AREAS OF FROST.
ANOTHER DRY COLD FRONT MOVING THROUGH WED NIGHT/EARLY THURSDAY
WILL BE FOLLOWED BY A MODERATELY GUSTY NORTHERLY WIND (IN THE
20S - MPH) ON THURSDAY.
AVIATION /07Z TUESDAY THROUGH SATURDAY/
HIGH PRESSURE AND VERY DRY AIR ARE ALLOWING FOR CONTINUED DRY
CONDITIONS AND CLEAR SKIES ACROSS THE MAJORITY OF THE FORECAST
AREA THIS EVENING. SOME VALLEY FOG ACROSS NORTHWESTERN
PENNSYLVANIA IS STARTING TO FORM BASED ON ECONUS NIGHTTIME
MICROPHYSICS; HOWEVER, FOG CONTINUES TO REMAIN WEST OF ALL
CENTRAL PENNSYLVANIA AIRFIELDS. CURRENT THINKING BASED ON
OBSERVATIONS AND MODEL GUIDANCE IS THAT FOG MAY MAKE A CLOSER
APPROACH TO BFD CLOSER TO SUNRISE BUT OVERALL EXPECTING VFR
CONDITIONS TO CONTINUE THROUGH THE OVERNIGHT PERIOD.
AS A COASTAL STORM CRAWLS SLOWLY NORTH INTO EARLY TOMORROW, A
TIGHTENING PRESSURE GRADIENT HAS RESULTED IN INCREASING N TO NE
FLOW. THIS HAS SET UP A PERIOD OF LOW-END LOW-LEVEL WIND SHEAR
FOR THE EASTERN AIRFIELDS (IPT, LNS, MDT) INTO EARLY TUESDAY
MORNING AS WINDS AT THE SURFACE REMAIN LIGHT DUE TO A STABLE
NOCTURNAL BOUNDARY LAYER. SLIGHTLY AFTER SUNRISE, DIURNAL
HEATING WILL ALLOW THE STABLE BOUNDARY LAYER TO GIVE WAY TO
DEEPER MIXING RESULTING IN WIND GUSTS IN THE 15-20 KT RANGE FOR
THE EASTERN AIRFIELDS.
WED-SAT...PATCHY AM FOG AND FROST POSSIBLE IN THE NORTH AND WEST;
OTHERWISE, VFR CONDITIONS WILL PREVAIL.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...LAMBERT
KEY MESSAGES...LAMBERT
DISCUSSION...LAMBERT
AVIATION...BEATY
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