039
FXUS61 KCTP 210248
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1048 PM EDT SUN SEP 20 2026
WHAT HAS CHANGED
* TWEAKS TO NEAR TERM BASED ON RADAR/SAT TRENDS
* FLOOD WATCH CONSIDERED, REJECTED FOR NOW
KEY MESSAGES
1) RAIN MOVES TO THE SOUTH EARLY TONIGHT, BUT RETURNS FOR
MONDAY. FLOOD WATCH STILL POSSIBLE WITH THE SUPPORT OF LATER
MODEL GUIDANCE.
2) RAIN POTENTIAL CONTINUES FOR MUCH OF THIS WEEK, ALTHOUGH
UNCERTAINTY REMAINS IN THE DETAILS DUE TO OFFSHORE LOW
DEVELOPMENT POSSIBILITIES. ON THE COOL SIDE AS WELL.
DISCUSSION
KEY MESSAGE 1: RAIN MOVES TO THE SOUTH EARLY TONIGHT, BUT RETURNS
FOR MONDAY. FLOOD WATCH STILL POSSIBLE WITH THE SUPPORT OF
LATER MODEL GUIDANCE.
THE VAST MAJORITY OF THE STRONGER CONVECTION MOVING THROUGH
CENTRAL AND SOUTHERN OHIO THIS EVENING IS AIMED SW OF OUR SW
LAUREL HIGHLAND ZONES OVERNIGHT PER THE LATEST HREF AND ITS HIGH
RES MEMBERS.
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KEY MESSAGE 2: RAIN POTENTIAL CONTINUES FOR MUCH OF THIS WEEK,
ALTHOUGH UNCERTAINTY REMAINS IN THE DETAILS DUE TO OFFSHORE LOW
DEVELOPMENT POSSIBILITIES. ON THE COOL SIDE AS WELL.
A FAIRLY STRONG SHORT WAVE TROUGH CURRENTLY OVER ROLLS IN FROM
THE MIDWEST LATE TONIGHT. THAT SHOULD YIELD A RENEWAL OF
RAINFALL IN THE LAURELS. THE SYSTEM WILL STILL BE WORKING WITH
1.5-2.0" PWATS. BUT, IT WILL ARRIVING AT AN EVEN MORE- STABLE
TIME OF DAY. THE STEADY EAST AND SLIGHTLY NORTHWARD SPREAD OF
PRECIP WILL ONLY REINFORCE THE STABILITY (AND KEEP TEMPS CHILLY)
MONDAY. AGAIN, THUNDER CANNOT BE RULED OUT, BUT WOULD LIKELY BE
ELEVATED. IT MAY REMAIN DRY (OR JUST PATCHY DRIZZLE) ACROSS THE
NORTHERN TIER FOR MUCH OF THE DAY. MODELS FUNNEL THE BEST
MOISTURE INTO THE EASTERN HALF OF PA MONDAY NIGHT, EASING THE
FLOODING POTENTIAL SOMEWHAT FOR THE LAURELS.
24 HOUR QPF ENS LPMM IN THE 12Z MON-00Z TUE PERIOD SHOWS AT MOST
1-1.5 INCHES ACROSS SOUTHERN SOMERSET COUNTY WITH LESS THAN 0.25
OF AN INCH NE OF THE RT 322 CORRIDOR IN CENTRAL PA AND THE LOWER
SUSQ VALLEY. ANOTHER PERIOD OF SLIGHTLY MORE EXPANSIVE 1-1.5
INCH AMOUNTS IS EXPECTED FOR MONDAY NIGHT THROUGH TUESDAY
MORNING, AND COULD ENHANCE THE FLOODING THREAT ACROSS THE SW
THIRD OF THE CWA. BUT WITH LITTLE INSTABILITY/ HEAVY RAINFALL
RATES LIKELY, THERE'S PLENTY OF TIME AT THIS POINT TO FINE TUNE
THE AREA TO MESSAGE FOR THIS POTENTIAL MODERATELY IMPACTFUL
EVENT.
EXTREMELY BLOCKY PATTERN ALOFT YIELDS VERY LOW CONFIDENCE IN
SFC FEATURES AND PRECIP POTENTIAL/PLACEMENT BEYOND TUESDAY. LOW
PRESSURE TRIES TO DEVELOP OFF SHORE (ALONG THE GULF STREAM) WED,
BUT MAY BE SHUNTED EASTWARD THROUGH THE SECOND HALF OF THE
WEEK. THE SURE BET THIS WEEK IS FOR BELOW NORMAL MAX TEMPS.
AVIATION /02Z MONDAY THROUGH FRIDAY/
COLD FRONT WILL CONTINUE TO SAG SOUTHWARD OVERNIGHT, TAKING
MOST OF THE SHOWERS WITH IT. EXPECT WIDESPREAD IFR AND MVFR
CONDITIONS WITH A LOT OF VARIATION.
FOR MONDAY, MAIN CHANGE WAS TO BACK OFF ON IMPROVEMENT BEING
QUITE AS GOOD AS WHAT THE 18Z TAF PACKAGE HAD. LOW LEVEL
MOISTURE REMAINS HIGH.
MONDAY WILL FEATURE THE BEST CONDITIONS WITH THE LEAST CHANCE
OF SHOWERS OF THE NEXT FEW DAYS.
WET WEATHER IS EXPECTED TO MOVE BACK INTO THE AREA AFTER
MONDAY.
OUTLOOK...
TUE-THU...RESTRICTIONS POSSIBLE FROM -SHRA/BR AND LOW CEILINGS,
MAINLY S.
CLIMATE
AS OF 5 PM, 1.05 INCHES OF RAIN FELL AT AOO (ALTOONA) PA TODAY.
THIS BROKE THE OLD RECORD OF 0.73 INCHES SET IN 1957.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...LAMBERT/DANGELO
KEY MESSAGES...LAMBERT/DANGELO
DISCUSSION...LAMBERT/DANGELO/COLBERT
AVIATION...MARTIN
CLIMATE...MARTIN
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