608
FXUS61 KCTP 060917
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
517 AM EDT SAT JUN 6 2026
WHAT HAS CHANGED
* INCREASING CONFIDENCE IN SEVERE WEATHER THIS AFTERNOON AND
EVENING
* WPC HAS INCLUDED THE LAUREL HIGHLANDS IN A SLIGHT RISK FOR
EXCESSIVE RAINFALL
KEY MESSAGES
1) SEVERE WEATHER IS INCREASINGLY LIKELY THIS AFTERNOON AND
EVENING.
2) WARMTH SURGES AGAIN NEXT WEEK WITH A CLASSIC SUMMERLIKE
PATTERN EXPECTED - THOUGH UNCERTAINTY REMAINS.
DISCUSSION
KEY MESSAGE 1: SEVERE WEATHER IS INCREASINGLY LIKELY THIS
AFTERNOON AND EVENING.
AN UPPER SHORTWAVE TROUGH DIVING OUT OF THE GREAT LAKES REGION WILL
BRING AN INCREASING CHANCE FOR SHOWERS/T-STORMS THIS AFTERNOON
AND EVENING. SPC MAINTAINS A LEVEL 2/5 (SLGT) SEVERE T-STORM
RISK, WHICH INCLUDES ALL OF CENTRAL PA. OF NOTE, THE WIND
PROBABILITIES ARE 30 PERCENT SOUTH OF ROUTE 6 (HIGHER THAN THE
15 PERCENT PROBABILITIES THAT WE SEE WITH MOST SLIGHT RISKS).
LATEST HIRES GUIDANCE CONTINUES TO SHOW SPREAD WITH RESPECT TO
THE NUMBER AND TIMING OF CONVECTIVE ELEMENTS THROUGH THE DAY
SATURDAY. RADAR TRENDS DO SHOW MORNING RAIN SHOWERS UPSTREAM OF
OUR NW ZONES, BUT ANYTHING BEFORE 1 PM WILL LIKELY BE
NONSEVERE.
THE HIGHEST CHANCE FOR SEVERE WEATHER WILL BE IN THE LATE
AFTERNOON AND EVENING HOURS, SPARKED BY A BOOST OF LARGER SCALE
ASCENT LINKED TO THE THERMALLY DIRECT, RIGHT ENTRANCE REGION OF
A ROBUST MID AND UPPER LEVEL JET SEGMENT AS WELL AS POSITIVE
VORTICITY ADVECTION ALOFT. SBCAPE CLIMBS TO NEAR 1500 J/KG
THIS AFTERNOON AND EARLY EVENING WITH SFC-6 KM SHEAR OF 30-40
KTS. THE PRIMARY TRIGGERING MECHANISM FOR CONVECTION INITIATION WILL
LIKELY BE A PREFRONTAL SFC TROUGH SET UP JUST INLAND FROM LAKE
ERIE, AS WELL AS ANY COLD POOLS FROM PREEXISTING CONVECTION
MOVING IN FROM THE WEST. HODOGRAPHS ARE PRIMARILY STRAIGHT (WEST
TO EAST) AND MAY SUPPORT SPLITTING SUPERCELLS EARLY ON, BUT AS
COLD POOLS GROW/MERGE WE ANTICIPATE UPSCALE GROWTH INTO LINE
SEGMENTS WITH PREFERRED STORM MOTION TOWARDS THE SOUTHEAST.
DAMAGING WINDS AND LARGE HAIL WILL BE THE PRIMARY SEVERE
HAZARDS, BUT A TORNADO CAN NOT BE RULED OUT PARTICULARLY IN
WESTERN ZONES WHERE THERE IS A LITTLE MORE TURNING IN THE LOW
LEVELS OF THE ATMOSPHERE. LARGE HAIL WOULD ALSO BE FAVORED MORE
IN THE WESTERN ZONES, ESPECIALLY IN ANY SUPERCELLS THAT MAY
DEVELOP PRIOR TO LINEAR MODES. IN TERMS OF WIND, SEVERAL OF THE
HRRR RUNS OVER THE PAST 24 HOURS HAVE SHOWN FAIRLY LARGE BOW
ECHOS DEVELOPING WITH WIND GUSTS OF 50-65 MPH EMBEDDED WITHIN
THEM, BUT THERE ARE CONSIDERABLE RUN TO RUN DIFFERENCES IN THE
TRACK OF THESE CONVECTIVE ELEMENTS.
MODEL GUIDANCE REMAINS GENERALLY DRY ON SUNDAY, WITH MUCH OF
THE PRECIP ENDING AROUND MIDNIGHT TONIGHT. RAINFALL TOTALS ARE
EXPECTED TO BE HIGHEST IN THE WEST AND SOUTHWEST (UP TO 1 INCH),
WITH STORMS PRODUCING LESS RAINFALL OVER THE SOUTHEAST AS THE
EVENING WEARS ON AND DAYTIME HEATING IS LOST. THIS PATTERN DOES
NOT BODE WELL FOR ONGOING DROUGHT CONDITIONS. THERE IS A WPC
SLGT ERO IN THE LAURELS, BUT DRY ANTECEDENT CONDITIONS WILL
LIKELY OFFSET THE FLOOD POTENTIAL.
PATCHY FOG WILL BE POSSIBLE LATE TONIGHT INTO SUNDAY MORNING AS
CLOUDS CLEAR OUT BEHIND THE COLD FRONT AND THE WET GROUND
ALLOWS FOR SFC RH NEAR 100 PCT IN SPOTS. KEY LIMITING FACTOR
WILL BE HOW QUICKLY THE WINDS DIMINISH AS SKIES CLEAR OUT.
--------------------------------------------------------
KEY MESSAGE 2: WARMTH SURGES AGAIN NEXT WEEK WITH A CLASSIC
SUMMERLIKE PATTERN EXPECTED - THOUGH UNCERTAINTY REMAINS.
FOLLOWING A MODEST COOL DOWN ON MONDAY, EMERGING MODEL DATA
CONTINUES TO SIGNAL ABOVE NORMAL TEMPERATURES FOR THE REST OF
NEXT WEEK. EVEN THE COOL DOWN ON MONDAY WILL SEE ABOVE NORMAL
HIGH TEMPERATURES FOR MOST OF THE AREA. LONG RANGE MODELS
DIVERGE ON POTENTIAL SOLUTIONS TOWARD THE END OF NEXT WEEK. A
PREVAILING RIDGE IN PLACE OVER THE EASTERN US WILL ENSURE ABOVE
NORMAL TEMPERATURES (80S AND 90S), BUT MODELS DIVERGE IN HOW
THEY HANDLE AN UPPER CLOSED LOW MOVING OUT OF THE SOUTH CENTRAL
US UP TOWARDS THE GREAT LAKES. LATEST NBM HAS 20-40 PCT POPS
COVERING AT LEAST A PORTION OF CENTRAL PA EACH DAY TUESDAY
THROUGH THE END OF THE COMING WEEK, BUT REALISTICALLY MUCH OF
THAT TIME PERIOD MAY END UP DRY IF THE UNSETTLED WEATHER WITH
THE AFOREMENTIONED UPPER DISTURBANCE PASSES TO OUR WEST.
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
MINIMAL CLOUD COVER IS EXPECTED THROUGH 12Z SATURDAY OUTSIDE OF
SOME THIN MID-LEVEL CLOUDS CURRENTLY BEING OBSERVED AT
AIRFIELDS JUST WEST OF THE REGION (ERI/IDI) THAT WILL FILTER
INTO THE NORTHWESTERN TERMINALS (BFD/UNV). RECENT NBM/HREF BLEND
BRINGS IN SOME SHOWER CHANCES TO BFD ~12Z SATURDAY WITH A LOW-
END TSRA THREAT THROUGH ~15Z, THUS HAVE INTRODUCED THIS NARROW
WINDOW ALONG WITH DRYING CONDITIONS AND SOME BREAKS IN CLOUD
COVER ACROSS ALL OF CENTRAL PENNSYLVANIA FOR THE LATE
MORNING/EARLY AFTERNOON HOURS WITH MODERATE-TO-HIGH (~60-70%)
CONFIDENCE BASED ON RECENT HREF/GLAMP MODEL GUIDANCE. IN THIS
EARLIER TIMEFRAME, MARGINAL LLWS THRESHOLDS COULD BE MET AT
BFD/JST WITH A STRENGTHENING WESTERLY LLJ; HOWEVER, BULK OF
GUIDANCE KEEPS THE MAGNITUDE OF THIS SHEAR JUST LOW ENOUGH TO
KEEP MENTIONS OUT OF THE 06Z TAF PACKAGE.
THE MAIN PERIOD OF CONCERN FOR AVIATION PURPOSES ACROSS CENTRAL
PENNSYLVANIA REMAINS AFTER 18Z SATURDAY THROUGH 12Z SUNDAY WITH
SEVERE THUNDERSTORM POTENTIAL (DAMAGING WINDS/LARGE HAIL MAIN
CONCERNS) AND POTENTIAL FOR FOG FORMATION OVERNIGHT INTO SUNDAY
MORNING. RECENT GUIDANCE CONTINUES TO DEVELOP TSRA IN VERY CLOSE
PROXIMITY TO BFD IN THE ~19Z-21Z SATURDAY TIMEFRAME. GIVEN
AMPLE DESTABILIZATION AND SHEAR, EXPECT TSRA TO LARGELY GROW
UPSCALE AND IMPACT ALL OF THE WESTERN TERMINALS AS THIS COMPLEX
SHIFTS MAINLY SOUTHWARD (WITH A SLIGHT EASTERLY COMPONENT)
ACROSS THE FORECAST AREA. THE 06Z TAF PACKAGE DOES HIGHLIGHT
BFD/JST/AOO/UNV AS MOST PROBABLE FOR TSRA AT THE AIRFIELD, WITH
HREF PROBABILITIES REACHING BETWEEN 30%-50% OF LIGHTNING
OCCURRING AT THESE AIRFIELDS WHILE FURTHER SOUTH/EAST THERE
REMAINS SLIGHTLY LOWER PROBABILITIES DUE TO MORE BROKEN STORM
COVERAGE. DESPITE HIGHER PROBABILITIES, THE 06Z TAF PACKAGE
OUTLINES PROB30S MAINLY DUE TO LOWER CONFIDENCE IN TIMING, WHICH
WILL HOPEFULLY BE TIGHTENED UP IN FUTURE TAF PACKAGES. IN TSRA
ACROSS WESTERN TERMINALS, DAMAGING WINDS WILL BE THE MAIN HAZARD
AND GAVE SOME THOUGHT TO INCLUDING HIGH WINDS/GUSTS IN TSRA
MENTIONS; HOWEVER, WOULD LIKE TO SEE SLIGHTLY HIGHER CONFIDENCE
IN WHERE TSRA FIRE THIS EVENING BEFORE INCLUDING THOSE MENTIONS.
AFTER 00Z SUNDAY, MENTIONS FOR SHRA/TSRA DECREASE ACROSS MUCH
OF THE AREA; HOWEVER, CLEARING SKIES WILL ALLOW FOR FOG
FORMATION AND RESTRICTIONS POSSIBLE BETWEEN 00-12Z SUNDAY.
CURRENT HREF OUTLINES HIGHEST PROBABILITIES FOR IFR/LIFR
CONDITIONS AT BFD/JST; HOWEVER, REASONABLE WORST-CASE SCENARIO
EXTENDS THESE MENTIONS TO AOO/UNV/IPT CLOSER TO SUNRISE.
OUTLOOK...
SUN-TUE...VFR FAVORED OUTSIDE OF ISOLATED MORNING FOG.
RESTRICTIONS POSSIBLE IN -SHRA/-TSRA EARLY SUN & AGAIN LATE
TUE.
WED...RESTRICTIONS POSSIBLE IN -SHRA/-TSRA.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...COLBERT
KEY MESSAGES...LAMBERT/COLBERT
DISCUSSION...LAMBERT/COLBERT
AVIATION...BEATY
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