398
FXUS61 KCTP 292157
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
557 PM EDT WED MAR 29 2023
SYNOPSIS
A STRONG COLD FRONT WILL SWEEP SOUTHEAST FROM LAKE ERIE ACROSS
THE ALLEGHENIES THIS EVENING ACCOMPANIED BY LOCALLY HAZARDOUS
TRAVEL CONDITIONS. A RAPID DROP IN TEMPERATURES TONIGHT WILL
PRECEDE DRY WEATHER TOMORROW. THEN,A WARMING TREND IS EXPECTED INTO
THE WEEKEND WITH PERIODS OF RAIN AND STRONG GUSTY WINDS AS
MARCH ENDS MORE LIKE A LION THAN A LAMB. THE PATTERN WILL REMAIN
BREEZY AND TURN NOTICEABLY COLDER INTO SATURDAY NIGHT FOLLOWED
BY IMPROVING CONDITIONS AND A NICE START TO THE FIRST WEEK OF
APRIL.
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
PARTLY CLOUDY SKIES AND A SEASONABLE DAY ONGOING ACROSS THE
COMMONWEALTH. CLOUD COVER WILL CONTINUE TO INCREASE AND SPREAD
SOUTHEASTWARD THIS AFTERNOON AS A MILDER WEST/SOUTHWEST WIND
PICKS UP THIS AFTERNOON. VERY STEEP LOW LEVEL LAPSE RATES (ON
THE ORDER OF 10C/KM) WITH MIXING UP TO 8-10KFT WILL HELP BRING
25 TO 35 MPH WIND GUSTS TO THE SURFACE ACROSS NW PA AS THE
AFTERNOON WEARS ON. STILL ON TRACK FOR MAXTS RANGING FROM THE
UPPER 40S IN THE WESTERN & NORTHERN MTNS TO THE MIDDLE AND TO
UPPER 50S ACROSS CENTRAL RIDGES THROUGH THE SUSQUEHANNA VALLEY.
A STRONG COLD FRONT IS PROGGED TO PLOW SOUTHEAST FROM LAKE ERIE
ACROSS THE WESTERN & CENTRAL ALLEGHENIES THIS EVENING. THE
HIRES CAMS SHOW A BAND OF MODERATE TO LOCALLY HEAVY RAIN AND
SNOW SHOWERS ACCOMPANYING THE FRONT THROUGH THE REGION. THERE IS
EVEN ENOUGH INSTABILITY TO THE MENTION A SLIGHT CHANCE OF A
THUNDERSTORM THANKS TO A STRENGTHENING LOW LEVEL THERMAL
GRADIENT AND STEEP LAPSE RATES. SPC HAS ALSO INCLUDED NORTHWEST
AND NORTH CENTRAL PA IN THE DAY 1 GENERAL T-STORM OUTLOOK.
TONIGHT'S SYSTEM WILL BRING REDUCED VISIBILITY, GUSTY WINDS,
AND PLUMMETING TEMPERATURES, BUT THE ORDER AND TIMING OF THESE
HAZARDS WILL BE VERY IMPORTANT TO CONSIDER WITH EXPECTED
IMPACTS. A BURST OF LOCALLY HEAVY SNOW SHOWERS AND GUSTY WINDS
WILL BRING A SHARP DROP IN VISIBILITY IN NORTHWEST PA AND AS FAR
SOUTHEAST AS THE I-80/I-99 CORRIDOR. HREF PROBABILITIES OF
SNOWFALL RATES >1" PER HOUR PEAK AROUND 60% IN NORTHERN CENTRAL
PA. A MITIGATING FACTOR FOR IMPACTS FROM HEAVY SNOWFALL RATES
WILL BE VERY WARM ANTECEDENT ROAD CONDITIONS. RWIS SITES SHOW
ROAD TEMPERATURES IN THE 60S TO 80S F AS OF 1PM AND THESE
TEMPERATURES WILL CERTAINLY RISE FOR THE NEXT COUPLE HOURS
THROUGH PEAK HEATING. ALTHOUGH THE SNOWFALL RATES & GUSTY WINDS
ARE OFTEN CHARACTERISTIC OF SNOW SQUALLS, THE COLD AIR WILL
TRAIL BEHIND THE COLD FRONT AND SHOULD MITIGATE FLASH FREEZE
POTENTIAL COINCIDENT WITH PRECIPITATION. AT MOST, WOULD EXPECT
SOME SLUSHY ROADWAYS IN NORTHWEST PA AND PERHAPS ALONG US-6, BUT
ROADWAYS FARTHER SOUTH AND EAST (I-80, I-99) SHOULD PRIMARILY
REMAIN WET (ICE FREE) WHEN VISIBILITIES ARE REDUCED FROM
PRECIPITATION. THE BEST ODDS FOR SNOW ACCUMS WILL BE ON GRASSY
OR ELEVATED SURFACES, WHERE UP TO 1 INCH IS POSSIBLE.
SOON AFTER THE COLD FRONT SWEEPS THROUGH AND PRECIPITATION ENDS,
TEMPERATURES WILL PLUMMET BEHIND THE FRONT (10-20F OVER A
SEVERAL HOUR DURATION). THIS COULD LEAD TO A FLASH FREEZE AND
RESULT IN ICY SPOTS ON BRIDGES, OVERPASSES, AND UNTREATED
SECONDARY ROADS. THE WPC WINTER STORM SEVERITY INDEX SHOWS
MODERATE IMPACTS FROM FLASH FREEZE ACROSS NORTHWEST PA WITH
MINOR IMPACTS EXTENDING TO THE I-99/I-80 CORRIDOR. THOUGH THE
FLASH FREEZE WILL BE DISPLACED FROM THE PRECIPITATION AS IS
TYPICAL FOR A SNOW SQUALL, THE COMBINATION OF BRIEF HEAVY SNOW,
SUDDEN DROPS IN VISIBILITY, AND SHARPLY COLDER
TEMPERATURES/FLASH FREEZE ALL CONTRIBUTE TO THE POTENTIAL FOR
LOCALLY HAZARDOUS TRAVEL CONDITIONS THROUGH THIS EVENING.
THE FRONTAL PRECIP BAND IS EXPECTED TO WEAKEN AS IT CONTINUES
TO DESCEND THE HIGHER TERRAIN WITH DOWNSLOPE FLOW LIKELY HELPING
TO LIMIT RAIN/SNOW SHOWERS FROM REACHING SOUTHEAST OF THE
I81/I78 CORRIDOR. PRECIPITATION ALONG THE FRONT SHOULD CLEAR THE
AREA BY MIDNIGHT AND ANY LINGERING SNOW SHOWERS BEHIND THE
FRONT SHOULD DISSIPATE BY THURSDAY MORNING AS 1030MB HIGH
REACHES WESTERN PA. BY THURSDAY MORNING, EXPECT CLEAR SKIES AND
LOW TEMPERATURES RANGING FROM NEAR 20F IN THE NORTHERN MOUNTAINS
TO AROUND FREEZING IN THE LOWER SUSQUEHANNA VALLEY.
SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/
EXPECT ANOTHER RELATIVE COOL DOWN ON THURSDAY WITH HIGHS 5F TO
10F LOWER VS. WEDNESDAY. THAT SAID, THE COOL DOWN MAY NOT BE
QUITE AS NOTICEABLE AS THE MONDAY-TUESDAY TEMP TRANSITION WITH
A MUCH LIGHTER WIND AND PLENTY OF SUNSHINE. HIGHS IN THE 40-50F
RANGE WILL BE 5-15F BELOW LATE MARCH CLIMO. AN INCREASING
SOUTHERLY FLOW AND DEVELOPING WAA PATTERN SHOULD FAVOR A NON
DIURNAL TEMP TREND THURSDAY NIGHT WITH AND MINTS A FEW TO
SEVERAL DEGREES WARMER THAN WEDNESDAY NIGHT.
HIGH PRESSURE WILL SLIDE OFF THE EAST COAST FRIDAY MORNING WITH
A SOUTHERLY FLOW DEVELOPING. THIS SHOULD LEAD TO SIGNIFICANTLY
MILDER TEMPERATURES FOR THE END OF THE WEEK AND INTO THE FIRST
PART OF THE WEEKEND. CURRENT GUIDANCE SUPPORTS TEMPERATURES IN
THE 50S AND 60S ON FRIDAY WITH AN ADDITIONAL 10 DEGREES ADDED TO
THOSE HIGHS ON SATURDAY AFTERNOON. THE REALIZATION OF SUCH WARM
TEMPERATURES ON FRIDAY AND SATURDAY WILL BE DEPENDENT ON THE
EXTENT OF PRECIPITATION DURING THE DAY AND HOW QUICKLY A STRONG
COLD FRONT MOVES THROUGH. THERE REMAINS SOME UNCERTAINTY IN
TIMING AND EXTENT OF PRECIPITATION, BUT CONFIDENCE IS HIGH IN A
WIDESPREAD SOAKING RAINFALL FRI-SAT.
AS THE COLD FRONT SWEEPS THROUGH ON SATURDAY, TIMING WILL BE
IMPORTANT FOR THE POTENTIAL THREAT OF SEVERE WEATHER. ARRIVAL IN
THE AFTERNOON DURING PEAK HEATING ON SATURDAY WOULD FAVOR MORE
STORMS AND PERHAPS HIGHER SEVERE WEATHER CHANCES. EARLIER/LATER
ARRIVAL IN THE MORNING OR LATE EVENING WOULD LIMIT THE SEVERE
THREAT, BUT IT BEARS WATCHING. RAIN MAY ALSO MIX WITH OR CHANGE
TO WET SNOW BEHIND THE FRONT LATER SATURDAY NORTH AND WEST OF
THE I-99 AND I-80 CORRIDOR, WITH LITTLE TO NOT ACCUM EXPECTED.
AHEAD OF AND AFTER THE COLD FRONT SWEEPS THROUGH, EXPECT GUSTY
WINDS TO DEVELOP THANKS TO A DEEPENING SURFACE LOW OVER QUEBEC.
THE WIND THREAT LOOKS FORMIDABLE WITH THIS SYSTEM AND GUSTS IN
EXCESS OF 40MPH APPEAR PLAUSIBLE FOR MOST OF THE AREA SATURDAY
AFTERNOON.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
THE BLUSTERY WINDS WILL BEGIN TO DIMINISH SATURDAY NIGHT, AND
ANY LINGERING RAIN/SNOW SHOWERS ACROSS THE NORTH/WEST SHOULD
TAPER OFF AS HIGH PRESSURE BUILDS IN FROM THE OHIO VALLEY.
AFTER A SEASONABLY CHILLY SUNDAY, TEMPERATURES ARE EXPECTED TO
MODERATE HEADING INTO EARLY NEXT WEEK. MEDIUM RANGE MODELS SHOW
PREDOMINANTLY ZONAL UPPER LEVEL FLOW TO BEGIN THE WEEK, WITH A
WEAK SHORTWAVE CROSSING THE NORTHEASTERN UNITED STATES MON
NIGHT INTO TUESDAY ALONG WITH AN ASSOCIATED WEAK COLD FRONT.
HOWEVER, THERE ARE SOME DIFFERENCE BETWEEN THE MEDIUM RANGE
MODELS WITH THE SENSIBLE WEATHER EARLY NEXT WEEK. THE 12Z/29
GFS/GEFS ALLOWS THE WEAK COLD FRONT TO TAP INTO SOME GULF
MOISTURE AND PRODUCES A FEW RAIN SHOWERS MON NIGHT INTO TUESDAY,
WHILE THE 00Z/29 ECMWF/ECENS SHOWS A DRIER SOLUTION. REGARDLESS,
BOTH MODELS ARE IN AGREEMENT IN BRINGING A MORE SIGNIFICANT
FRONTAL SYSTEM INTO THE AREA BY THE MIDDLE OF NEXT WEEK WITH A
BETTER SHOT AT SOME WET WEATHER.
AVIATION /22Z WEDNESDAY THROUGH MONDAY/
THE FOCUS THIS EVENING WILL BE ON A POTENT COLD FRONT
CROSSING CENTRAL PA IN THE 21Z-03Z TIMEFRAME. STEEP LAPSE RATES
AHEAD OF THE FRONT WILL RESULT IN WEST TO SOUTHWESTERLY WIND
GUSTS BETWEEN 20-25KTS OVER MUCH OF THE REGION THIS EVENING AND
25-30KTS OVER THE NORTHWEST MOUNTAINS.
CONVECTION-ALLOWING MODELS ALL SUPPORT A BAND OF SNOW
SHOWERS/SQUALLS ACCOMPANYING THE FROPA OVER THE N AND W MTNS
THIS EVENING. A BRIEF DIP TO LIFR VSBYS APPEARS VERY LIKELY AT
KBFD BETWEEN 22Z-23Z, WHILE A DIP TO IFR/LIFR IS LIKELY AT KJST
BETWEEN 00Z-01Z. IMPACTS SHOULD BE LESS SIGNIFICANT FURTHER
SOUTH AND EAST, AS THE BAND OF SHOWERS IS LIKELY TO EITHER
DISSIPATE OR FALL PRIMARILY AS RAIN OVER THE LOWER ELEVATIONS OF
THE SUSQ VALLEY LATE THIS EVENING. HOWEVER, CAN'T COMPLETELY
RULE OUT A BRIEF DIP TO IFR AT EITHER KAOO OR KUNV BETWEEN
01Z-02Z. HIGH PRESSURE WILL BUILD IN BEHIND THE COLD FRONT
LATER TONIGHT, RESULTING IN CLEARING SKIES AND A DIMINISHING
WIND.
WIDESPREAD VFR CONDITIONS AND LIGHT WINDS ARE A NEAR CERTAINTY
THURSDAY, AS HIGH PRESSURE BUILDS OVER THE STATE.
OUTLOOK...
FRI...PM RAIN/LOW CIGS DEVELOPING FROM WEST TO EAST.
SAT...AM SHOWERS/REDUCED CIGS POSSIBLE, THEN TURNING WINDY WITH
LATE DAY SNOW SHOWERS POSSIBLE N/W.
SUN-MON...NO SIG WX EXPECTED.
FIRE WEATHER
LOW HUMIDITY AND THE BREEZY CONDITIONS THIS AFTERNOON SUGGEST
AN ELEVATED RISK OF WILDFIRE SPREAD. HOWEVER, COORDINATION WITH
THE PA BUREAU OF FORESTRY (PABOF) INDICATES THAT AN ADDITIONAL
DAY OF DRYING/CURING IS NEEDED TO RAISE FIRE WEATHER CONCERNS.
WE EXPECT MINIMUM RH TO BOTTOM IN THE 15-25% RANGE THURSDAY
AFTERNOON, BUT LIGHTER WINDS AND COOLER TEMPERATURES (40-50F) SHOULD
MITIGATE AN ELEVATED RISK OF WILDFIRE SPREAD.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...STEINBUGL/BANGHOFF
NEAR TERM...STEINBUGL/BANGHOFF
SHORT TERM...STEINBUGL/BANGHOFF
LONG TERM...EVANEGO
AVIATION...FITZGERALD/EVANEGO
FIRE WEATHER...
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