553
FXUS61 KCTP 011826
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
226 PM EDT TUE JUL 1 2025
SYNOPSIS
* DAMAGING WIND AND HEAVY RAINFALL THREAT THIS AFTERNOON;
SIGNIFICANT FLASH FLOODING IMPACTS POSSIBLE
* DRIER/LESS HUMID/MORE COMFORTABLE CONDITIONS ARE LIKELY FOR
MID TO LATE WEEK WITH A HIGH CONFIDENCE OF DRY WEATHER AND
SEASONABLE TEMPERATURES ON INDEPENDENCE DAY
* TRENDING WARMER AND MORE HUMID THIS WEEKEND; UNSETTLED PATTERN
RETURNS BY SUNDAY
NEAR TERM /UNTIL 11 PM THIS EVENING/
*SEVERE THUNDERSTORM WATCH #481 IN EFFECT UNTIL 9PM EDT THIS
EVENING FOR SOUTH CENTRAL PA
*FLOOD WATCH IN EFFECT UNTIL 11PM EDT THIS EVENING FOR SOUTH
CENTRAL PA
PEAK WIND GUSTS FROM WATER-LOADED DOWNDRAFTS OBSERVED SO FAR
EARLY THIS AFTERNOON HAVE BEEN IN THE 25-30KT RANGE. STEEPER LOW
LEVEL LAPSE RATES ACROSS THE LOWER SUSQUEHANNA VALLEY SUGGEST A
GREATER RISK FOR STRONG TO POTENTIALLY SEVERE WIND GUSTS. RADAR
TRENDS HAVE BEEN INCREASING IN INTENSITY WITH EASTERN EXTENT.
FAIRLY PROGRESSIVE STORM MOTIONS HAVE TENDED TO OFFSET FF RISK
SO FAR, HOWEVER RAIN RATES HAVE BEEN VERY EFFICIENT AT >1"/HR.
PREVIOUS DISCUSSION ISSUED: 1217 PM EDT TUE JUL 1 2025
SEVERE T-STORM THREAT VIA SPC MCD #1529
CONVECTION IS BUILDING TO THE EAST ACROSS SOUTHWEST INTO SOUTH
CENTRAL PA AT MIDDAY AHEAD OF A LOW-AMPLITUDE SHORTWAVE TROUGH
THAT IS PROGRESSING EAST ACROSS THE UPPER OH VALLEY. WHILE THERE
IS SOME NEAR-TERM UNCERTAINTY OF HOW QUICKLY THIS INITIAL
ACTIVITY WILL STRENGTHEN AMID WEAK DCAPE, THE DOWNSTREAM AIRMASS
IS DESTABILIZING QUITE WELL WITH SFC TEMPS INTO THE MID 80S.
THIS WILL YIELD AN UPTICK IN CONVECTIVE INTENSITY AS CLUSTERS
IMPINGE ON RICHLY MOIST AIRMASS WHERE 70-75F SURFACE DEW POINTS
ARE PERVASIVE. ALTHOUGH LOWER-LEVEL WINDS WILL REMAIN WEAK AND
PREDOMINATELY VEERED, MODERATE MID TO UPPER-LEVEL WESTERLIES
WILL SUPPORT ORGANIZED MULTICELLS CAPABLE OF PRODUCING MULTIPLE
STRONG TO ISOLATED SEVERE GUST SWATHS. SCATTERED DAMAGING WINDS
APPEAR LIKELY TOWARDS MID TO LATE AFTERNOON.
A SEVERE TSTM WATCH IS LIKELY TO BE ISSUED BY 17Z/1PM.
FLASH FLOODING: FF THREAT REMAINS LOCKED IN ACROSS SOUTH CENTRAL
AND SOUTHEAST PA. 12Z IAD SOUNDING CAME IN WITH DAILY RECORD
PWAT OF 2.07" ALONG WITH A DAILY RECORD WBZ 0 HEIGHT SUPPORTING
A VERY DEEP WARM-CLOUD LAYER WITHIN THE LOWER TROPOSPHERE. THIS
ENVIRONMENT ALONG WITH TALL/SKINNY CAPE PROFILES ARE HIGHLY
REPRESENTATIVE OF A STRONG PROSPECT FOR NOT ONLY HEAVY RAIN, BUT
SIGNIFICANT RATE DRIVEN CORES (2-3+ IN/HR) THAT CAN EFFICIENTLY
DROP SEVERAL INCHES OF RAIN IN A VERY SHORT SPAN OF TIME. THE
POTENTIAL MAGNITUDE OF RAIN/RATES COMBINED WITH VERY SATURATED
ANTECEDENT CONDITIONS WITH LOCALLY 4-6" IN SOME SPOTS IN THE
PAST 24 HRS SUGGEST SIGNIFICANT FLASH FLOODING IMPACTS ARE
POSSIBLE. FROM A HISTORICAL PERSPECTIVE, THE WPC MODERATE RISK
OF EXCESSIVE RAINFALL (RISK LEVEL 3 OUT OF 4) TYPICALLY ONLY
OCCURS 5-6X A YEAR IN PA, AND THIS IS THE SECOND MDT RISK IN THE
PAST 30 DAYS. WPC SHOULD SEND A NEW MPD WITH MORE DETAILS
SHORTLY.
SHORT TERM /11 PM THIS EVENING THROUGH FRIDAY/
SHOWER ACTIVITY SLOWLY SHIFTS TO THE SOUTHEAST TONIGHT WITH ANY
POST FRONTAL CLEARING EXPECTED TO RESULT IN FOG FORMATION INTO
WEDNESDAY MORNING. THE LATEST HREF ALSO SUGGESTS SOME LOW CLOUDS
AND STRATUS MAY LINGER INTO THE EARLY MORNING WEDNESDAY.
ON BALANCE, THIS PERIOD WILL FEATURE A DRYING TREND WITH LITTLE
TO NO RAINFALL AND MORE COMFORTABLE HUMIDITY. BEST ODDS FOR A
COUPLE OF PM SHOWERS/T-STORM WILL BE THURSDAY AFTERNOON
ASSOCIATED WITH A SECONDARY COLD FRONT MOVING SOUTHEAST FROM
EASTERN CANADA AND THE NORTHERN GREAT LAKES.
WE CONTINUE TO HAVE HIGH CONFIDENCE/CONVICTION IN A REALLY NICE
INDEPENDENCE DAY WITH A NEAR ZERO CHANCE FOR RAIN AND GREAT
VIEWING FOR FIREWORKS. MIN TEMPS FRIDAY NIGHT WILL BE QUITE
COMFORTABLE IN THE LOW 50S TO LOW 60S.
HUMIDITY LEVELS START TO CREEP UPWARD TO START THE FIRST
WEEKEND OF JULY; HOWEVER IT WILL REMAIN DRY WITH UNSETTLED
WEATHER EXPECTED TO RETURN SUNDAY INTO EARLY NEXT WEEK.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
LOW PRESSURE APPROACHING THE GREAT LAKES BY SUNDAY MORNING WILL
BRING ABOUT INCREASING CHANCES FOR PRECIPITATION FOR THE SECOND
HALF OF THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
A COLD FRONT MOVING THROUGH TODAY WILL SEE ANOTHER ROUND OF
T-STORM IMPACTS EXPECTED THIS AFTERNOON ACROSS CPA AIRSPACE.
OVERALL WIDESPREAD SHOWERS AND THUNDERSTORMS ARE LIKELY, WITH
MOST AIRFIELDS EXPECTED TO SEE VISIBILITY REDUCTIONS FROM HEAVY
RAIN AND THUNDERSTORMS. GUSTS WITH THESE STORMS COULD REACH UP
TO 40KTS. COVERAGE AND OF STORMS WILL QUICKLY DIMINISH BEHIND
THE FRONT, AND MOST RAIN IS EXPECTED TO BE CONFINED TO THE
SOUTHEAST BY 00Z.
CLOUDS WILL BECOME SCATTERED TO CLEAR OVERNIGHT TONIGHT INTO
EARLY TOMORROW MORNING AS DRYER AIR IS USHERED IN BEHIND THE
FRONT. FOG WILL BE A CONCERN TONIGHT INTO EARLY WEDNESDAY
MORNING.
OUTLOOK...
WED...AM FOG, THEN VFR.
THU...PRIMARILY VFR; STRAY PM SHOWER/T-STORM POSSIBLE.
FRI-SAT...AM FOG POSSIBLE; OTHERWISE VFR.
CTP WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR PAZ017>019-
024>028-033>036-049-050-052-056>059-063>066.
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...BANGHOFF/NPB
AVIATION...BOWEN
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