899
FXUS61 KCTP 171910
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
310 PM EDT WED SEP 17 2025
SYNOPSIS
* SEVERAL BANDS OF LIGHT TO MODERATE RAIN/SHOWERS PUSHING WEST
ACROSS THE SUSQUEHANNA VALLEY AND SOUTH-CENTRAL MOUNTAINS OF
PA TODAY AND TONIGHT, WITH THE COOLEST HIGH TEMPERATURES OF
THE WEEK OCCURRING TODAY.
* RAINFALL AMOUNTS GENERALLY BETWEEN ONE TENTH AND ONE QUARTER
OF AN INCH. LOCALLY OVER ONE HALF OF AN INCH ACROSS PORTIONS
OF THE LOWER SUSQUEHANNA VALLEY.
* DRY CONDITIONS RETURN AREAWIDE ON THURSDAY AND WILL PERSIST
THROUGH THE WEEKEND WITH TEMPERATURES REBOUNDING TO WELL-ABOVE
NORMAL.
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
A PERSISTENT DEEP EASTERLY FLOW WILL SUPPORT SEVERAL BANDS OF
LIGHT TO BRIEFLY MDT/HVY SHOWERS WESTWARD OVER THE SE 1/3 OF OF
CWA LATE THIS AFTERNOON AND INTO EARLY TONIGHT.
NEAR, AND JUST TO THE SE OF THE I-99/RT 220, A FEW LIGHTER RAIN
SHOWERS WILL LIKELY OCCUR, BUT WON'T AMOUNTS TO MORE THAN A
FEW/SVRL HUNDREDTHS OF AN INCH IN MOST PLACES.
THE GENERALLY THICK CLOUD COVER ACROSS THE SE TWO THIRDS OF THE
CWA, PERSISTENT EASTERLY FLOW WILL KEEP TEMPERATURES
SIGNIFICANTLY COOLER THAN RECENT DAYS.
FOR TONIGHT, THE AFOREMENTIONED COASTAL LOW WILL MOVE OFF THE NJ
COAST AND THE SINGLE, CLOSED-CONTOUR UPPER LEVEL LOW WILL
TRANSITION TO A POSITIVE-TILT. OPEN WAVE CAUSING THE LOW TO MID
LEVEL FLOW TO BACK THROUGH THE NE THEN NORTH BY MORNING. THIS
WILL LEAD TO A SIGNIFICANT DECREASE IN POPS AND AREAL COVERAGE
FOR SHOWERS BY OR SHORTLY AFTER MIDNIGHT TONIGHT.
SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/
THURSDAY AND FRIDAY WILL BE A CONTINUATION OF WHAT WE'VE SEEN
FOR A MAJORITY OF THE PAST COUPLE WEEKS WITH PLENTY OF SUNSHINE,
SEASONABLY MILD TEMPERATURES, AND LIGHT WINDS. IT WILL TAKE A
LITTLE WHILE FOR THE MOISTURE IN SOUTHEAST PA TO BE REPLACED BY
A DRIER AIRMASS, SO EXPECT THE AIR TO FEEL A BIT HUMID STILL ON
THURSDAY. HIGHS WILL GENERALLY BE IN THE 80S WITH LOWS IN THE
UPPER 40S (NW) TO LOWER 60S (SE). A BACKDOOR, MOISTURE-DEPRIVED
COLD FRONT WILL SAG SOUTH INTO NORTHERN PENNSYLVANIA FRIDAY
AFTERNOON, WITH AN INCREASE IN CLOUD COVER NORTH OF US-6 BEING
THE ONLY NOTEWORTHY ASPECT OF ITS ARRIVAL. DRIER AIR AWAITS IN
ITS WAKE...
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
FRIDAY NIGHT - THE AFOREMENTIONED BACKDOOR COLD FRONT WILL
SLIDE THROUGH PENNSYLVANIA WITH A STRONG 1028MB HIGH SURGING IN
BEHIND IT. DEWPOINTS WILL PLUMMET BY SATURDAY MORNING,
SUPPORTING A RETURN TO BELOW-NORMAL OVERNIGHT TEMPERATURES WITH
CLEAR SKIES AND CALM WINDS. SURFACE HIGH PRESSURE WILL SET UP
OFF THE NEW ENGLAND COAST FOR THE WEEKEND, ENSURING MOIST
SOUTHEAST FLOW AND TRANQUIL WEATHER. HIGHS WILL TICK DOWN A FEW
DEGREES FOR THE WEEKEND, WITH HIGHS IN THE 70S AND LOWS IN THE
50S MOST LIKELY AT THIS TIME.
HEADING INTO NEXT WEEK, HIGH PRESSURE WILL BEGIN TO LOSE ITS
GRIP ON THE REGION AS AN UPPER TROUGH TRIES TO DISRUPT THE
PERSISTENT RIDGE OF HIGH PRESSURE ALOFT. STILL PLENTY OF
UNCERTAINTY ON HOW MUCH, IF ANY, PRECIPITATION WILL GET INTO
PENNSYLVANIA BUT SOUTHERLY FLOW AHEAD OF THE APPROACHING SYSTEM
WILL SUPPORT CONTINUED WARMER THAN AVERAGE TEMPERATURES FOR THE
START OF ASTRONOMICAL FALL.
AVIATION /19Z WEDNESDAY THROUGH MONDAY/
SHOWERS WILL CONTINUE TO ROTATE INTO SOUTHEASTERN PA ON THE
NORTHWESTERN SIDE OF A LOW PRESSURE SYSTEM CURRENTLY LOCATED
EAST OF MARYLAND AND WILL CONTINUE TO IMPACT MDT AND LNS FOR
MUCH OF THE DAY. THE MAIN CONCERN WITH THE NEXT SEVERAL HOURS IS
HOW LOW CEILINGS WILL GET AS THESE SHOWERS CONTINUE TO MOVE NEAR
THE SITES OF MDT AND LNS. CONFIDENCE IS HIGH FOR MVFR, AND
GUIDANCE SEEMS TO SUGGEST CLOUD HEIGHTS WILL STAY ABOVE IFR
CONDITIONS FOR THE REMAINDER OF THIS AFTERNOON.
SHOWERS GRADUALLY EXPAND NORTHWARD THROUGH THE DAY AND MAY
REACH AS FAR NORTH AND WEST AS UNV AND IPT. THOSE SITES, ALONG
WITH AOO, MAY SEE A PERIOD OF MVFR CEILINGS AS SHOWERS APPROACH,
BUT CONFIDENCE IS NOT HIGH ON THAT OCCURRING. WHILE THERE HAS
BEEN A FEW LIGHTNING STRIKES OBSERVED THIS MORNING AROUND MDT
AND LNS, WEAK INSTABILITY SHOULD LIMIT THE LIGHTNING THREAT
TODAY. WINDS WILL GENERALLY BE OUT OF THE NORTHEAST AT 5 TO 10
KNOTS WITH A FEW GUSTS TO 15 KNOTS POSSIBLE IN SOUTHEAST PA.
SHOWERS GRADUALLY SHIFT EASTWARD AS THE LOW MOVES AWAY FROM THE
AREA, AND WILL COME TO AN END BY 00Z.
WIDESPREAD FOG FORMATION APPEARS LIKELY ACROSS MUCH OF THE AREA,
WITH IFR CIGS/VSBY POSSIBLE AT ALL TAF SITES AFTER 06Z. THE
TIMING OF THESE RESTRICTIONS WILL NEED TO BE REFINED WITH LATER
FORECASTS.
OUTLOOK...
THU...GENERALLY VFR.
FRI-SUN...VFR WITH AM VALLEY FOG.
CLIMATE
ASTRONOMICAL FALL OFFICIALLY BEGINS WITH THE AUTUMNAL EQUINOX
ON MONDAY, SEPTEMBER 22, 2025 @ 2:19 P.M. EDT. THE AUTUMN 2025
SEASON WILL LAST 89 DAYS, 20 HOURS, AND 43 MINUTES. DAYLIGHT
SAVING TIME WILL END JUST AFTER HALLOWEEN WITH CLOCKS FALLING
BACK AT 2 A.M. SUNDAY, NOVEMBER 2, 2025.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...LAMBERT/GARTNER
NEAR TERM...LAMBERT/GARTNER
SHORT TERM...LAMBERT/GARTNER
LONG TERM...LAMBERT/BANGHOFF
AVIATION...BAUCO/BOWEN
CLIMATE...STEINBUGL
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