995
FXUS61 KCTP 160404
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1104 PM EST FRI NOV 15 2024
SYNOPSIS
*MOSTLY CLOUDY OVERNIGHT WITH LIMITED VIEWING OF THE SUPER
BEAVER MOON & ISS FLYOVER
*DRY, BREEZY, AND MILDER START TO THE WEEKEND WITH PARTIAL
CLEARING AND ELEVATED WILDFIRE SPREAD RISK IN EAST CENTRAL PA
*CONTINUED MILD AND DRY THROUGH TUESDAY; NEXT RAINFALL LIKELY
DURING THE SECOND HALF OF NEXT WEEK
NEAR TERM /UNTIL 7 AM SATURDAY MORNING/
LOW LEVEL MOISTURE TRAPPED BENEATH A SUBSIDENCE INVERSION IS
PRODUCING WIDESPREAD STRATUS ACROSS CENTRAL PA THIS EVENING WITH
FOG SHROUDED RIDGES, WHILE A DOWNSLOPING NORTHWEST FLOW
YIELDS A FEW BREAKS ACROSS THE SUSQ VALLEY. A STEADY LIGHT
RAIN/DRIZZLE IS BEING OBSERVED THIS EVENING OVER THE LAUREL
HIGHLANDS, IN THE VICINITY OF AN INVERTED SURFACE TROUGH, WHERE
MOISTURE IS DEEPER AND THERE IS SOME MODEST LOW LEVEL
CONVERGENCE ALONG THE BOUNDARY. THEREFORE, WILL PLACE THE
HIGHEST POPS OVER SOMERSET/CAMBRIA COUNTIES THIS EVENING, WHILE
A MORE SHALLOW LAYER OF UPSLOPING MOISTURE RESULTS IN LOW POPS
OVER THE NW MTNS, AND SUBSIDENCE SOUTHEAST OF THE ALLEGHENIES
RESULTS IN A DRY NIGHT THERE. THE SURFACE TROUGH IS PROGGED TO
SHIFT SOUTH OF THE STATE LATE TONIGHT, RESULTING IN A
DIMINISHING CHANCE OF DRIZZLE OVER THE W MTNS.
MODEL SOUNDINGS INDICATE LITTLE CHANGE IN CLOUD COVER OVERNIGHT,
WITH SKIES RANGING FROM OVERCAST OVER THE W MTNS TO PARTLY
CLOUDY SOUTHEAST OF HARRISBURG. LOW LEVEL COLD ADVECTION BEHIND
THE EXITING SURFACE TROUGH SHOULD PUSH READINGS STEADILY
DOWNWARD LATE TONIGHT, DESPITE CLOUD COVER AND AN ACTIVE BREEZE.
EXPECT TEMPS AT DAWN TO RANGE FROM THE UPPER 30S OVER THE NW
MTNS, TO THE LOW AND MID 40S EAST OF THE ALLEGHENY PLATEAU.
SHORT TERM /7 AM SATURDAY MORNING THROUGH MONDAY/
FALLING INVERSION HEIGHTS UPON THE APPROACH OF HIGH PRESSURE
WILL RESULT IN BREAKING CLOUDS SATURDAY, WITH UPSLOPING
NORTHWEST FLOW RESULTING IN THE MOST PERSISTENT CLOUD COVER OVER
THE W MTNS. MODEL SOUNDINGS INDICATE THE NW MTNS WILL BE THE
LAST TO CLEAR, WITH BREAKING CLOUDS NOT ANTICIPATED THERE UNTIL
AROUND DUSK. ABUNDANT AFTERNOON SUNSHINE SHOULD PUSH TEMPS 5-7
DEGREES ABOVE CLIMO (UPPER 50S) OVER THE SUSQ VALLEY BASED ON
GEFS 2M TEMP ANOMALIES, WHILE LINGERING LOW CLOUDS SHOULD HOLD
READINGS TO THE UPPER 40S OVER THE ALLEGHENY PLATEAU.
A FAIRLY TIGHT GRADIENT BETWEEN UPSTREAM HIGH PRESSURE OVER THE
GRT LKS AND LOW PRESSURE OFF OF THE EAST COAST WILL RESULT IN
GUSTY NORTHWEST WINDS SATURDAY. BUKFIT SOUNDINGS SUPPORT
FREQUENT GUSTS IN THE 20-25KT RANGE FROM LATE MORNING THROUGH
LATE AFTERNOON, WITH THE STRONGEST GUSTS ACROSS THE EASTERN PART
OF THE FORECAST AREA. SEE FIRE WX SECTION FOR LATEST THINKING
CONCERNING FWW/RFW/SPS.
A NORTH-SOUTH ORIENTED SURFACE HIGH PRESSURE RIDGE IS PROGGED TO
PUSH INTO PA SAT NIGHT, RESULTING IN DIMINISHING WIND AND MOSTLY
CLEAR SKIES. LATEST SREF AND NAMNEST BOTH INDICATE VALLEY FOG IS
A GOOD BET SAT NIGHT, ESPECIALLY OVER THE ALLEGHENIES, WHERE
THE WINDS SHOULD DIMINISH EARLIEST.
FAIR WEATHER AND LIGHT WIND ARE ANTICIPATED SUNDAY UNDER THE
HIGH PRESSURE SYSTEM. HOWEVER, WARM ADVECTION ALOFT IN ADVANCE
OF A SHORTWAVE OVER THE GRT LKS IS LIKELY TO SPREAD A VEIL OF
CIRRUS OVER THE REGION, ESPECIALLY IN THE NORTH. PROGGED 850MB
TEMPS SURGE TO 20 DEGREES ABOVE CLIMO SUNDAY. HOWEVER, WEAK
MIXING UNDER THE SURFACE RIDGE WILL RESULT A MORE MODEST WARMUP
WITH HIGHS IN THE 50S TO AROUND 60F.
A NORTHERN STREAM SHORTWAVE WILL PIVOT ACROSS THE EASTERN GREAT
LAKES INTO NEW ENGLAND LATE SUNDAY NIGHT INTO EARLY MONDAY.
THIS FEATURE WILL SEND A WEAK COLD FRONT THROUGH THE REGION
AND TRIGGER SOME LIGHT RAIN SHOWERS DOWNWIND OF LAKE ERIE CLOSE
NEAR AND TO THE NORTH OF THE NY BORDER. RIDGING SFC AND ALOFT
RETURNS FOR THE REST OF MONDAY, BRINGING DRY CONDITIONS WITH
MILDER DAYTIME TEMPERATURES IN THE 55-65F RANGE (+10-15 DEGREES
ABOVE THE HISTORICAL AVERAGE).
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
UPPER LEVEL RIDGING OVER PA SHOULD PROVIDE THE REGION WITH MILD
AND MOSTLY RAIN-FREE CONDITIONS TUESDAY. HOWEVER, WARM ADVECTION
ASSOCIATED WITH A WEAKENING SHORTWAVE LIFTING INTO THE GRT LKS
MAY PRODUCE A FEW SHOWERS, MAINLY OVER THE NW MTNS. FOCUS THEN
SHIFTS TO A CUT-OFF UPPER LOW DROPPING INTO THE MIDWEST. A
COLD/OCCLUDED FRONT IS PROGGED TO SWEEP ACROSS PA AHEAD OF THIS
FEATURE WED PM, ACCOMPANIED BY A ROUND OF SHOWERS. MEAN QPF
BASED ON THE 18Z EPS IS AROUND A HALF INCH WED/WED NIGHT.
HOWEVER, THERE IS A WIDE SPREAD IN THE GUIDANCE. A DECENT
NUMBER OF ENSEMBLE MEMBERS ARE MUCH WETTER (1-2 INCHES),
REPRESENTING THE CHANCE THAT MOISTURE FROM SARA'S REMNANTS ARE
DRAWN NORTH INTO PA AHEAD OF THE FRONT.
ALL MEDIUM RANGE GUIDANCE SUPPORTS UNSETTLED AND CHILLY WEATHER
THURSDAY AND FRIDAY, AS THE UPPER LOW EITHER PASSES OVER OR JUST
NORTH OF PA. A MOIST NORTHWEST FLOW ON THE WESTERN PERIPHERY OF
THE UPPER LOW, COMBINED WITH LAKE EFFECT MOISTURE, SUPPORTS A
PERIOD OF UPSLOPE PRECIPITATION ACROSS THE ALLEGHENY PLATEAU
THU PM THROUGH FRIDAY. THERMAL PROFILES LOOK COLD ENOUGH DURING
THIS TIMEFRAME FOR A RAIN/SNOW MIX OVER THE ALLEGHENY PLATEAU,
WITH THE POTENTIAL OF SOME ACCUMULATION, ESPECIALLY ON THE
RIDGETOPS. A NORTHWEST FLOW SHOULD YIELD LIGHTER, MORE
INTERMITTENT RAIN SHOWERS IN THE LOWER ELEVATIONS EAST OF THE
ALLEGHENIES.
AVIATION /04Z SATURDAY THROUGH WEDNESDAY/
CONFIDENCE REMAINS HIGH (90%) IN LIFR TO IFR CONDITIONS FOR THE
REST OF THE DAY AT JST AND BFD. MAIN QUESTION IS HOW LONG THE
1/4 SM VSBY REMAINS AT JST. WINDS HAVE VEERED AROUND TO BECOME
NW, WHICH MAY HELP THE VSBY TREND UP TO A MILE OR MORE BY 19-20Z,
BUT CAN'T RULE OUT THAT LOWER VSBY CONTINUES THROUGH MUCH OF
THE DAY WITH CIGS BEING SO LOW.
CIGS AT UNV REMAIN IFR, WITH LOW END MVFR / HIGH END IFR AT AOO.
EXPECT THESE CONDITIONS TO CONTINUE THROUGH 20-23Z BEFORE SLIGHT
IMPROVEMENT. THE EASTERN TERMINALS (IPT/MDT/LNS) WILL STAY OUT
OF IFR, BUT TEMPO MVFR CIGS ARE LIKELY AT IPT, MDT, AND LNS.
FLOW OFF THE GREAT LAKES WILL REINFORCE THE LOW LEVEL MOISTURE
TONIGHT, AND COULD TAKE IPT, MDT, AND LNS BACK TO MVFR AFTER
07Z SAT (LOWER CHANCES TOWARDS THE SOUTHEAST).
THE NW WIND ABOVE THE SUBSIDENCE INVERSION WILL INCREASE THIS
EVENING, BRINGING ABOUT SOME WEAK LLWS LATE TONIGHT INTO EARLY
SAT. THE SIGNAL IS STRONGEST OVER MDT/LNS, WHERE A TIGHT
GRADIENT DEVELOPS BETWEEN THE DEPARTING LOW AND THE HIGH MOVING
IN FROM THE WEST. LOW LEVEL SHEAR WILL DISSIPATE SAT MORNING AS
TURBULENT EDDIES BRING WIND GUSTS DOWN TO THE SFC. EXPECT SAT
AFTN SFC GUSTS INTO THE M20S AT MDT AND LNS. CIGS WILL REMAIN
MVFR IN THE NW SAT AM, THEN FINALLY IMPROVE TO VFR AT JST AND
BFD AROUND 17-20Z SAT.
OUTLOOK...
SUN...MAINLY VFR.
SUN NIGHT - EARLY MON...CFROPA. MVFR CIGS/VIS IN -SHRA, MAINLY
N HALF.
MON PM-TUES...NW FLOW. IFR/MVFR CIGS NW, VFR SE.
WED...RESTRICTIONS POSS, MAINLY NW. MORE WIDESPREAD RESTRICTIONS
WITH RAIN AND LLWS WED NIGHT.
FIRE WEATHER
AN ELEVATED RISK OF WILDFIRE SPREAD IS EXPECTED SATURDAY
AFTERNOON OVER THE EASTERN PORTION OF CENTRAL PENNSYLVANIA
-- DUE TO A COMBINATION OF GUSTY WINDS 25-35 MPH FROM THE
NORTHWEST, LOW RELATIVE HUMIDITY (<40%) AND DRY FUELS. THE LACK
OF CURING TODAY COMBINED WITH AN UPTICK IN MINRH HAS LEAD US TO
HOLD OFF ON UPGRADING TO RFW OR EXPANDING THE FWW. COORDINATION
CONSENSUS WITH FIRE PARTNERS SUPPORTS RIDING THE WATCH THROUGH
SATURDAY (IN LIEU OF CANCELING AND ISSUING SPS).
CTP WATCHES/WARNINGS/ADVISORIES
FIRE WEATHER WATCH FROM 9 AM EST SATURDAY THROUGH SATURDAY
AFTERNOON FOR PAZ051>053-057>059-066.
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD/STEINBUGL
LONG TERM...FITZGERALD
AVIATION...GARTNER/COLBERT
FIRE WEATHER...STEINBUGL
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