503
FXUS61 KCTP 091909
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
309 PM EDT TUE AUG 9 2022
SYNOPSIS
VERY WARM AND HUMID SUMMERTIME CONDITIONS TODAY WILL TREND MORE
SEASONABLE THROUGH MIDWEEK. ISOLATED TO SCATTERED THUNDERSTORMS
CAPABLE OF LOCALLY HEAVY RAINFALL WILL BE POSSIBLE NEAR THE
MASON DIXON LINE THIS AFTERNOON THROUGH WEDNESDAY. RELIEF FROM
THE HEAT AND HUMIDITY IS EXPECTED TO ARRIVE BY THE END OF THE
WEEK AND LAST THROUGH THE WEEKEND.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
1830Z RADAR SHOWS ISOLATED TO SCT CONVECTION CONFINED TO THE
SOUTH CENTRAL PA ALONG AND AHEAD OF LEADING SFC COLD FRONT.
LATEST SPC MESOANALYSIS SHOWS ROBUST MLCAPE 1500-2000 J/KG
WITHIN RIBBON OF ANOMALOUS PWATS AROUND 2 INCHES. THE LACK OF
DEEP LAYER SHEAR SHOULD KEEP THE MAJORITY OF STORMS NON-SEVERE;
HOWEVER STEEP LOW LEVEL LAPSE RATES AND WATER LOADING WILL
CONTRIBUTE LOCALIZED STRONG WIND GUSTS AROUND 30-35KTS (BASED
ON LATEST OBS FROM CXY/MDT). A SOMEWHAT GREATER, BUT STILL
MARGINAL CONCERN IS ISOLATED FLOODING. WITH PLENTY OF DEEP LAYER
MOISTURE AVAILABLE, BRIEF HEAVY TO TORRENTIAL DOWNPOURS WITH
RAIN RATES UP TO 2-3"/HR ARE POSSIBLE. SOMERSET COUNTY IS MOST
VULNERABLE WITH THE LOWEST FFGS, BUT PROGRESSIVE STORM MOTIONS
SHOULD HELP TO LIMIT THE FLOOD THREAT.
HEAT ADVISORY REMAINS IN EFFECT UNTIL 8PM FOR THE EASTERN
PORTION OF THE LSV WITH MAX HX VALUES 100-104F. AS OF 18Z: MDT,
LNS, CXY, AND THV HAVE ALL RECORDED MAX HX >=100F. COLD FRONT
WILL RESULT IN A ~20F MAXT GRADIENT THIS AFTERNOON WITH HIGHS
AROUND 75F IN THE NW ALLEGHENIES AND 95F IN THE SOUTHEAST.
THE COLD FRONT IS PROGGED TO STALL OUT NEAR THE MASON DIXON
LINE TONIGHT, KEEPING THE CHANCE OF LINGERING SHOWERS OVER
MAINLY SOUTHERN PA OVERNIGHT. TEMPERATURES WILL DIP INTO THE
MID-UPPER 50S ACROSS THE NORTHERN TIER, BUT IT WILL BE ANOTHER
WARM AND MUGGY ONE NEAR THE STALLED FRONT OVER SOUTHERN PA WITH
TEMPERATURES GENERALLY +5 TO +10F COMPARED TO NORMAL.
IF MIDDLETOWN CAN RECORD A 4TH STRAIGHT NIGHT WITH A LOW
TEMPERATURE OF 75F OR HIGHER, AND THE TEMPERATURE DOESN'T DROP
BELOW 75 BEFORE MIDNIGHT ON WEDNESDAY NIGHT, IT WOULD TIE FOR
THE 4TH LONGEST STRETCH ON RECORD (SEE CLIMATE SECTION FOR
MORE).
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/
WEDNESDAY WILL BE MORE SEASONABLE (NOT AS HOT/HUMID) AS THE
COLD FRONT WAVERS NEAR THE MASON DIXON LINE. ONE LAST ROUND OF
AFTERNOON CONVECTION SHOULD DEVELOP OVER THE SOUTHERN TIER OF
CPA WHERE PWS WILL REMAIN WELL ABOVE NORMAL AROUND 2 INCHES.
DESPITE HIGH FFG VALUES OVER MOST OF THE AREA, THE DEEP MOISTURE
AND POTENTIAL FOR CELL MERGERS OR REPEAT STORMS WILL MAINTAIN
AN ISOLATED FLOODING RISK.
BY WEDNESDAY NIGHT, THE FRONT AND ASSOCIATED RAIN SHOWERS WILL
EXIT THE FORECAST AREA WITH SKIES GRADUALLY CLEARING OUT ACROSS
THE NORTHWEST 1/2 TO 3/4 OF THE CWA. FCST MINT SHOULD DROP TO
AROUND 50F IN THE NW MTNS AS MUCH DRIER AIR STARTS TO WORK ITS
WAY INTO THE COMMONWEALTH. AIR TEMP/WATER SPREADS SHOULD SUPPORT
PATCHY FOG OVER THE NW ALLEGHENIES INTO EARLY THURSDAY MORNING.
LONG TERM /THURSDAY THROUGH TUESDAY/
THURSDAY MORNING WILL BE A GREAT TIME TO CHECK OUT THE PERSEIDS
METEOR SHOWER, WHICH PEAK AUGUST 11TH AND 12TH.
ALL GUIDANCE TRACKS A SECONDARY COLD FRONT THROUGH THE REGION
THURSDAY AHEAD OF A DEEPENING UPPER LEVEL TROUGH. DECENT LARGE
SCALE FORCING, AS INFERRED BY MODEL 500-300MB QVEC CONVERGENCE
FIELDS, IS ANTICIPATED WITH THE FROPA, BUT WILL KEEP POPS LOW
DUE TO A LACK OF MOISTURE.
THE LATEST ECENS AND GEFS BOTH SUPPORT A STRETCH OF COOL AND DRY
WEATHER NEXT FRIDAY INTO THE WEEKEND ASSOCIATED WITH CANADIAN
HIGH PRESSURE BUILDING SOUTHEAST ACROSS THE STATE. ENSEMBLE MEAN
850MB TEMPS OF 10-12C SUGGEST HIGHS TEMPS WILL BE A BIT BELOW
AVERAGE FRIDAY/SATURDAY, RANGING FROM THE 70S OVER MOST OF THE
AREA TO AROUND 80F IN THE SUSQ VALLEY. SATURDAY AND POSSIBLY
SUNDAY MORNINGS COULD BE CHILLY WITH LOWS IN THE 40S OVER THE
NORTHWEST MOUNTAINS, AS THE SURFACE HIGH BUILDS DIRECTLY OVER
THE STATE. MODERATING TEMPERATURES SHOULD BEGIN SUNDAY, AS THE
HIGH SLIPS OFF THE EAST COAST. IN GENERAL, MODEL CONSENSUS
FAVORS A CONTINUATION OF FAIR WEATHER WITH NEAR TO SLIGHTLY
BELOW AVERAGE TEMPERATURES INTO MONDAY AS UPPER TROUGH REMAINS
PARKED OVER THE EAST COAST. HOWEVER, ENSEMBLE QPF PLUMES SUGGEST
ISOLATED SHOWERS CAN'T BE RULED OUT LATE SUNDAY OR MONDAY
ASSOCIATED WITH WEAK SHORTWAVES DIVING SOUTHEAST FROM THE GRT
LKS. A BETTER CHANCE FOR RAIN WILL FOLLOW FOR TUE-WED.
AVIATION /19Z TUESDAY THROUGH SUNDAY/
HIGHEST MOISTURE (IN THE FORM OF AN SW-NE AXIS OF PRECIPITABLE
WATER OVER 2 INCHES JUST AHEAD OF A COLD FRONT) AND LOWEST CIGS
IN THE IFR TO LIFR RANGE WILL OCCUR AT KBFD, KJST AND POINTS
JUST TO THE SOUTHEAST INTO LATE THIS MORNING.
VFR TO OCNL MVFR CIGS WILL BE FOUND ACROSS THE CENTRAL MTNS AND
LAUREL HIGHLANDS OF PA (KUNV, KAOO AND KJST) THIS MORNING WHILE
THE SE PA AIRFIELDS WILL STAY VFR.
THE AFOREMENTIONED COLD FRONTAL BOUNDARY WILL DRIFT STEADILY SE
THROUGH THE REGION DURING THE LATE MORNING AND AFTERNOON HOURS
WITH A 2-4 HOUR PERIOD OF NUMEROUS SHOWERS AND SCATTERED TSRA
WITH BRIEF HEAVY RAIN AND FLIGHT REDUCTIONS INTO THE MVFR AND
IFR RANGE. THE PERIOD OF LOWEST CONDITIONS WILL OCCUR ACROSS THE
SE AFTER 18Z AND PERSIST UNTIL AROUND 23Z.
SHALLOW MOISTURE TRAPPED BENEATH THE SUBSIDENCE INVERSION IN THE
WAKE OF THE COLD FRONT TONIGHT WILL LIKELY RESULT IN WIDESPREAD
MVFR BKN-OVC CIGS WITH PERIODS OF IFR CIGS AT KJST AND KBFD.
THESE SAME MVFR CIGS (BUT MAINLY VFR VSBYS) SHOULD LINGER
THROUGHOUT MUCH OF WED ACROSS ROUGHLY THE SE HALF OF PA AS A
WEAK WAVE OF LOW PRESSURE RIDES NE ALONG THE STALLING FRONTAL
BOUNDARY TO OUR SE.
ALTHOUGH MOST OF WED WILL STAY DRY, A FEW PERIODS OF SHOWERS (OR
STEADY LIGHT RAIN) ARE EXPECTED ACROSS THE SE THIRD OF PA (KMDT
AND KLNS) LATE IN THE DAY AND WED NIGHT.
OUTLOOK...
WED-THU..SCT MAINLY AFTN/EVENING SHRA AND TSRA, WITH PATCHY
EARLY MORNING FOG/STRATUS.
FRI AND SAT...VFR/NO SIG WX.
CLIMATE
ALTHOUGH THE MAGNITUDE OF WARMTH AT HARRISBURG WILL NOT BE
ANYWHERE NEAR ANY RECORDS, THE DURATION OF WARM NIGHTS COULD BE.
HARRISBURG RECORDED A LOW TEMPERATURE OF 76F ON SUNDAY 8/7 AND
SUNDAY 8/8. IF THE TEMPERATURE DOES NOT FALL BELOW 75F BEFORE
MIDNIGHT, THE LOW TEMPERATURE WILL BE AT OR ABOVE 75F FOR 3
DAYS IN A ROW (ENDING TUESDAY MORNING), AND POSSIBLY 4 DAYS IN
A ROW (THROUGH WEDNESDAY).
HERE ARE SOME STATISTICS ABOUT TMIN>=75F AT HARRISBURG:
EXACTLY 3 NIGHTS IN A ROW: 6 TIMES ON RECORD AND NOW TWICE IN
THE LAST FEW WEEKS (7/21-7/23/2022 AND 8/7-8/9/2022)
EXACTLY 4 NIGHTS IN A ROW: 8 TIMES ON RECORD AND AS RECENTLY AS
7/16-7/19/2013
5 NIGHTS IN A ROW: 3 TIMES ON RECORD AND AS RECENTLY AS
8/10-8/14/2016.
CTP WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR PAZ057-059-065-
066.
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...COLBERT/BANGHOFF
AVIATION...STEINBUGL
CLIMATE...BANGHOFF
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