933
FXUS61 KCTP 162042
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
342 PM EST MON DEC 16 2024
SYNOPSIS
MILDER AND MOIST AIR OVERRUNNING THE COLD, DENSE AIRMASS
ENTRENCHED IN THE CENTRAL VALLEYS WILL LEAD TO RAIN ADVANCING
NE ACROSS THE REGION LATER THIS AFTERNOON THROUGH THE FIRST HALF
OF TONIGHT. STORM TOTAL RAINFALL AMOUNTS WILL BE BETWEEN 0.15
AND 0.45 INCH BY TUESDAY MORNING.
HIGH PRESSURE WILL BUILD INTO THE REGION TUESDAY INTO EARLY
WEDNESDAY. THEN A WEAK AREA OF LOW PRESSURE LIFTING OUT OF THE
OHIO VALLEY IS LIKELY TO PUSH INTO PENNSYLVANIA BY LATE
WEDNESDAY WITH ANOTHER PERIOD OF RAIN POSSIBLY ENDING AS SNOW.
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
A DULL AND DANK DAY ACROSS THE ENTIRE CWA WITH A VERY WEAK
PRESSURE GRADIENT AND SLIGHTLY MILDER/MOIST AIRMASS OVERRUNNING
THE COLD, SNOW-COVERED GROUND LEADING TO WIDESPREAD LOW STRATUS
AND RIDGE SHROUDING FOG.
AN UNUSUALLY SHORT GAP BETWEEN PRECIP PRODUCING SYSTEMS AND THE
NEXT ROUND OF (RAIN) WAS SPREADING INTO OUR SOUTHERN AND WESTERN
ZONES ATTM AND WILL ADVANCE ENE TO COVER THE ENTIRE CWA DURING
THE LATE AFTERNOON AND EVENING HOURS. THE LEADING EDGE OF
THE RAIN REACHES A LINE FROM MERCERSBURG, STATE COLLEGE AND
COUDERSPORT BY SUNSET.
MUCH OF THE STEADIER RAIN WILL BE ON THE FRONT END OF THE
SYSTEM EARLY THIS EVENING WHEN ISENTROPIC ASCENT AND MOISTURE
TRANSPORT ARE STRONGEST, WHILE ANY LINGERING RAIN AFTER MIDNIGHT
WILL LIKELY COME IN THE FORM OF SCATTERED SHOWERS.
ENSEMBLE MEAN RAINFALL BY THE PREDAWN HOURS OF TUESDAY WILL BE
THE GREATEST BETWEEN ROUTE 6 AND I-80 IN NORTHERN PA WHERE
AROUND 0.50 INCH OF RAIN COULD FALL, AND LEAST OVER THE SOUTHERN
VALLEYS WITH GENERALLY LESS THAN 0.25 INCH.
MIN TEMPERATURES WILL OCCUR EARLY TONIGHT WITH THE MERCURY
RISING VERY SLOWLY (ABOUT 2-4 DEG F) OVERNIGHT. LOOK FOR TEMPS
TO RANGE FROM THE UPPER 30S TO MID 40S BY DAYBREAK TUESDAY.
SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/
AFTER THE RAIN EXITS TO THE EAST EARLY TUESDAY, THERE WILL BE A
LIGHT TO MODERATE WESTERLY FLOW WITH GUSTS IN THE MID TEENS TO
AROUND 20 MPH. STRATUS DECK MAY BE STUBBORN TO BREAK ONCE AGAIN,
BUT THE CLOUD LAYER WILL BE ABOUT HALF AS THICK AS TODAY, AND
THE WESTERLY LLVL FLOW AND ASSOCIATED ADIABATIC WARMING/DRYING
SHOULD ALLOW SOME BREAKS OF SUN/BLUE SKY.
HIGH PRESSURE BRIEFLY ATTEMPTS TO BUILD IN BEHIND A COLD FRONT
TUESDAY NIGHT INTO THE FIRST HALF OF WEDNESDAY, WHICH WILL KEEP
THE REGION MAINLY DRY. TUESDAY WILL BE THE WARMEST DAY OF THE
PERIOD WITH HIGHS IN THE 40S AND 50S.
LONG TERM /WEDNESDAY THROUGH MONDAY/
THE NEXT SYSTEM WILL BE MORE ENERGETIC WITH RAIN RETURNING TO
THE FORECAST WEDNESDAY AFTERNOON OR EVENING, AS A DEVELOPING
SURFACE LOW TRACKS OVER OR JUST EAST OF PENNSYLVANIA AND A
PERIOD OF STRONG ISENT LIFT SPREADS ACROSS THE REGION IN
ASSOCIATION WITH THE PASSAGE OF A SOUTHWESTERLY LLJ OF 55-65
KTS. PRECIP WILL START OFF AS RAIN, BUT THE LATEST OPER MODELS
AND ENSEMBLES SUGGEST ENOUGH COULD AIR SHOULD MOVE IN FROM THE
WEST TO ALLOW FOR THE RAIN TO MIX WITH OR FULLY TRANSITION TO
SNOW FOR AREAS WEST OF THE ALLEGHENY FRONT. NORTHWESTERLY FLOW
BEHIND THIS SYSTEM SHOULD ALLOW FOR SOME LAKE EFFECT SNOW
SHOWERS TO CONTINUE INTO THURSDAY.
GUIDANCE IS BEGINNING TO COME INTO BETTER AGREEMENT IN REGARD TO
THE SYSTEM THAT WILL MOVE THROUGH IN THE FRIDAY/SATURDAY
TIMEFRAME. A WEAKENING SURFACE LOW WILL TRACK NEAR THE REGION ON
SATURDAY AND WHILE MOISTURE LOOKS FAIRLY LIMITED, MOST OF THE
REGION WILL LIKELY SEE LIGHT SNOW. UPSLOPE AND LAKE EFFECT SNOW
SHOWERS LINGER THROUGH THE DAY ON SATURDAY BEFORE HIGH PRESSURE
BUILDS IN FOR THE SECOND HALF OF THE WEEKEND AND INTO THE
BEGINNING OF NEXT WEEK.
TEMPERATURES WILL BE ON A DOWNWARD TREND THROUGH THE EXTENDED
PERIOD, WITH MUCH COLDER AIR WORKING INTO CENTRAL PA BY SUNDAY.
HIGH TEMPERATURES WILL BE IN THE 20S AND LOWS WILL BE IN THE
SINGLE DIGITS AND TEENS.
AVIATION /20Z MONDAY THROUGH SATURDAY/
WIDESPREAD IFR/LIFR CONDITIONS WILL CONTINUE THROUGHOUT THE
MAJORITY OF THE TAF PERIOD WITH HIGH (~80-90%) CONFIDENCE IN ALL
AIRFIELDS PREVAILING IFR TO LIFR THROUGH 12Z TUESDAY.
MILER AND MOIST AIR ALOFT STREAMING NE OVER THE SHALLOW, COLDER
AIR LOCKED IN PLACE ACROSS CENTRAL PA WILL HELP TO
FORM/TRANSPORT AN AREA OF STEADY LIGHT, TO BRIEFLY MODERATE
RAIN ACROSS ALL CENTRAL PA AIRFIELDS LATER THIS AFTERNOON
THROUGH TONIGHT.
THIS INJECTION OF MOISTURE AND AN UPTICK IN THE SOUTH TO
SOUTHEASTERLY LOW-LEVEL FLOW WILL KEEP IFR/LIFR RESTRICTIONS IN
PLACE ACROSS ALL AIRFIELDS THROUGH AT LEAST 10Z TUESDAY.
ANOTHER ASPECT OF FLIGHT CONDITIONS, MAINLY BETWEEN 22Z MONDAY
AND 10Z TUESDAY, WILL BE LLWS THRESHOLDS BEING MET WITH A SLIGHT
ENHANCEMENT OF SOUTHERLY WINDS AT 925MB ALLOWING FOR SOME SHEAR
WITH WINDS SOUTHWESTERLY WINDS AT THE SURFACE. THE AIRFIELDS OF
MOST CONCERN AT OF 06Z MONDAY REMAIN ACROSS EASTERN AIRFIELDS
(BFD/JST/AOO) WITH SLIGHTLY LOWER CONFIDENCE (BUT STILL
NOTEWORTHY IN THE 12Z TAF PACKAGE) AT UNV/IPT/MDT/LNS.
OUTLOOK...
TUE...IMPROVING CONDITIONS.
WED-THU...FOG POSSIBLE WED MORNING, THEN RAIN MOVES IN DURING
THE AFTERNOON AND CONTINUES INTO THURSDAY, BEFORE PARTIAL
CLEARING LATER THURSDAY.
FRI...RESTRICTIONS POSSIBLE WITH SNOW SHOWERS.
CLIMATE
ASTRONOMICAL WINTER (SOLSTICE) BEGINS ON SATURDAY, DECEMBER 21ST
AT 4:19 A.M. EST.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...LAMBERT/COLBERT
NEAR TERM...LAMBERT/COLBERT
SHORT TERM...LAMBERT/COLBERT
LONG TERM...LAMBERT/BAUCO
AVIATION...LAMBERT/NPB
CLIMATE...STEINBUGL
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