898
FXUS61 KCTP 011801
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
201 PM EDT TUE JUL 1 2025
SYNOPSIS
* INCREASING THREAT FOR DAMAGING WINDS AND HEAVY RAINFALL 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 WITH
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 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.
SHOWER ACTIVITY SLOWLY SHIFTS TO THE SOUTHEAST TONIGHT WITH ANY
POST FRONTAL CLEARING EXPECTED TO RESULT IN FOG FORMATION INTO
WEDNESDAY MORNING.
SHORT TERM /11 PM THIS EVENING THROUGH 6 PM WEDNESDAY/
THE FRONT SEEMS LIKE IT SHOULD BE CLEARING THE SE LATE THIS
EVENING, PERHAPS AROUND MIDNIGHT. THUS, THE PRECIP SHOULD BE
TAPERING OFF THEN. THE CLEARING ANTICIPATED BEHIND THE PRECIP
WILL PROBABLY CAUSE FOG, ESPECIALLY IN THE CENTRAL MOUNTAINS
WHERE THEY WON'T HAVE TIME TO DRY OUT LIKE THE NW MAY. CROSS-
LAKE FLOW MAY INTRODUCE A COUPLE OF SHOWERS OVER THE NW EARLY
TONIGHT. DEWPOINTS ONLY DIP TO AROUND 60F IN BFD, BUT 60+
NUMBERS REMAIN ACROSS THE REST OF THE CWA THROUGH MORNING. MOST
EVERYONE WILL GET DOWN TO THEIR DEWPOINT BY MORNING. HAVE ADDED
A BIT MORE FOG TO THE FORECAST FOR TONIGHT.
WED LOOKS LIKE A FAIR AND WARM SUMMER DAY. THE GRADIENT ISN'T
VERY STRONG BEHIND THE FRONT, SO THE WIND SHOULD BE UNDER 10MPH
OUT OF THE NW. MAXES GENERALLY 80-85F, WITH A DEG OR TWO
VARIANCE IN THE NORMAL COOL (ELEVATIONS) AND WARMER (URBAN)
SPOTS. THERE IS A SMALL (20 POP) CHANCE FOR A SHOWER OVER THE
FAR SE.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
HIGH PRESSURE BEGINS TO BUILD SOUTHWEST OF THE REGION,
PROVIDING FAIR WEATHER FOR THE MIDDLE OF THE WEEK AND INTO THE
WEEKEND. BEST CHANCES FOR PRECIPITATION THROUGH SATURDAY WILL
REMAIN DUE TO A COLD FRONTAL PASSAGE ACROSS THE NORTHERN HALF OF
PENNSYLVANIA. COLD FRONT REMAINS RELATIVELY MOISTURE-STARVED;
HOWEVER, GENERALLY THINK FORCING WILL BE ENOUGH TO CAUSE A
SHOWER AND AFTERNOON/EVENING THUNDERSTORM.
THE BIGGEST FEATURE OF THE POST-FRONTAL AIRMASS WILL BE MUCH
LOWER DEWPOINTS AND REFRESHING NIGHTS/MORNINGS. THERE IS HIGH
CONFIDENCE IN LOWS DROPPING INTO THE 50S AND LOW 60S THURSDAY
AND FRIDAY NIGHTS, WHICH WILL BE A SIGNIFICANT AND WELCOME
CHANGE FROM THE LONG-DURATION HEAT/HUMIDITY WE HAVE EXPERIENCED
OVER THE PAST FEW WEEKS. INDEPENDENCE DAY ACTIVITIES SHOULD BE
UNDER FAIR SKIES, COMFORTABLE TEMPERATURES, AND PLEASANT
NORTHWEST WINDS.
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...DANGELO
LONG TERM...BANGHOFF/NPB
AVIATION...BOWEN
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