986
FXUS61 KCTP 012223
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
623 PM EDT TUE JUL 1 2025
SYNOPSIS
* SHOWERS AND THUNDERSTORMS, SOME WITH LOCALLY HEAVY DOWNPOURS,
WILL GRADUALLY DIMINISH THROUGH THE EVENING HOURS
* 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/
*FLOOD WATCH IN EFFECT UNTIL 11PM EDT THIS EVENING FOR SOUTH
CENTRAL PA
615 PM UPDATE... THE MOST ROBUST CONVECTION IS NOW LARGELY ALONG
AND EAST/SOUTHEAST OF A PRE-FRONTAL SURFACE TROUGH OVER THE
COASTAL PLAIN, WHERE DEEPER INSTABILITY AND HIGHER PRECIPITABLE
WATER VALUES EXIST. ALTHOUGH HIT AND MISS SHOWERS AND
THUNDERSTORMS COULD STILL IMPACT CENTRAL PA THIS EVENING, AHEAD
OF THE MAIN SURFACE COLD FRONT THAT WILL BE SLOWLY COMING
THROUGH THE REGION, SEVERE STORMS WOULD SEEM EXTREMELY UNLIKELY,
THUS THE CANCELLATION OF THE SEVERE THUNDERSTORM WATCH.
GIVEN ONGOING RUNOFF ISSUES AND EXTREMELY WET ANTECEDENT
CONDITIONS, PARTICULARLY NEAR AND SOUTH OF I-78/US-22 IN THE
SUSQUEHANNA VALLEY, THE FLOOD WATCH WILL STAY IN TACT AT THIS
TIME.
PREVIOUS DISCUSSION... 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.
EARLIER 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 /22Z 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 PAZ057>059-065-
066.
SYNOPSIS...STEINBUGL
NEAR TERM...JUREWICZ/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...BANGHOFF/NPB
AVIATION...BOWEN
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