162
FXUS61 KCTP 180359
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1059 PM EST SUN NOV 17 2024
SYNOPSIS
A WEAKENING COLD FRONT WILL PUSH SOUTH ACROSS THE REGION MONDAY,
THEN RIDGING WILL BUILD ACROSS THE STATE MONDAY NIGHT INTO
EARLY WEDNESDAY. A CUT-OFF UPPER LOW WILL TRACK ACROSS FROM THE
GREAT LAKES INTO PENNSYLVANIA LATE THIS WEEK, PRECEDED BY AN
OCCLUDED FRONT PASSAGE WEDNESDAY NIGHT.
NEAR TERM /THROUGH MONDAY/
THE MAIN FOCUS TONIGHT WILL BE ON A DYING COLD FRONT
APPROACHING FROM THE GRT LKS. UPSTREAM RADAR SHOWS A BROKEN LINE
OF SHOWERS ACROSS LOWER MICHIGAN AND NEAR TERM MODEL GUIDANCE
INDICATES THE BEST CHANCE OF MEASURABLE RAIN WILL OCCUR NEAR THE
NY BORDER WITH THE PASSAGE OF THE LOW LEVEL JET AND DEEPEST
MOISTURE LATE TONIGHT. LATEST CONVECTION-ALLOWING MODEL
GUIDANCE INDICATES VERY LITTLE CHANCE OF RAIN MUCH SOUTH OF
ROUTE 6, AS THE PARENT SHORTWAVE AND BEST LARGE SCALE FORCING
PASS WELL NORTH OF PA.
DRY AIR AND LIGHT WINDS UNDER SURFACE RIDGE ARE RESULTING IN
DECENT RADIATIONAL COOLING THIS EVENING, DESPITE A VEIL OF HIGH
CLOUDS. MANY OF THE NORMALLY COLDER VALLEYS IN CENTRAL AND
NORTHERN PA ARE ALREADY DOWN INTO THE MID TO UPPER 30S AT
04Z. HOWEVER, A GENERAL INCREASE IN CLOUD COVER AND A
FRESHENING WESTERLY BREEZE SHOULD RESULT IN LIMITED ADDITIONAL
COOLING OVERNIGHT. MODEL TIME SERIES ALL INDICATE NEARLY STEADY
TEMPS THE REST OF THE NIGHT WITH READINGS AT DAWN RANGING FROM
THE MID 30S IN THE COLDER SPOTS OF THE MIDDLE SUSQ VALLEY, TO
THE MID 40S OVER THE NW MTNS/LAUREL HIGHLANDS.
LOW LEVEL MOISTURE POOLING AHEAD OF THE APPROACHING COLD FRONT,
COMBINED WITH UPSLOPING FLOW, MAY YIELD LOW CIGS AND RIDGETOP
FOG TOWARD DAWN OVER THE NW MTNS.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
THE DYING FRONT IS PROGGED TO SAG SOUTH THROUGH THE FORECAST
AREA MONDAY. WEAK FORCING AND RELATIVELY LOW PWATS SHOULD MAKE
IT A DRY FROPA. HOWEVER, LOW LEVEL MOISTURE POOLING AHEAD OF
THE FRONT, COMBINED WITH AN UPSLOPING WESTERLY FLOW, SHOULD
YIELD STRATUS ACROSS THE ALLEGHENY PLATEAU, WHICH WILL TEND TO
CLEAR FROM NORTH TO SOUTH, AS DRIER AIR ARRIVES BEHIND THE
FRONT. SUBSIDENCE TO THE LEE OF THE ALLEGHENIES SHOULD RESULT IN
MAINLY SUNNY SKIES ACROSS THE EASTERN HALF OF THE FORECAST AREA
MONDAY.
THE AIR MASS ALONG AND IMMEDIATELY BEHIND THE FRONT COLD FRONT
WILL BE WELL ABOVE AVERAGE AND INCREASING SUNSHINE SHOULD PUSH
AFTERNOON READINGS INTO THE 55-65F RANGE (+10-15 DEGREES ABOVE
THE HISTORICAL AVERAGE).
UPPER LEVEL RIDGING OVER THE AREA SHOULD PROVIDE CENTRAL PA
WITH MILD AND RAIN-FREE CONDITIONS MONDAY NIGHT AND MOST IF NOT
ALL OF TUESDAY. HOWEVER, WARM ADVECTION ASSOCIATED WITH A
WEAKENING SHORTWAVE LIFTING INTO THE GRT LKS SHOULD LEAD TO
INCREASING CLOUDS LATE TUESDAY/TUESDAY NIGHT WITH THE CHANCE OF
A FEW SHOWERS, MAINLY OVER THE W MTNS.
FOCUS THEN SHIFTS TO A CUT-OFF UPPER LOW DROPPING INTO THE
MIDWEST. MODEL SOUNDINGS INDICATE AN EASTERLY FLOW OFF OF THE
ATLANTIC WILL LIKELY YIELD STRATUS OVER PARTS OF THE AREA WED,
ESPECIALLY OVER THE CENTRAL MTNS. FALLING HEIGHTS AND SURGING
PWATS ALONG A SOUTHERLY LOW LEVEL JET SHOULD THEN BRING
THICKENING CLOUDS AND AN INCREASING CHANCE OF SHOWERS ACROSS THE
ENTIRE AREA BY LATE WEDNESDAY OR WED EVENING. WE MAY NEED TO
EVENTUALLY UNDERCUT NBM MAX TEMPS WED, DUE ITS WARM BIAS IN
EASTERLY FLOW/CAD SCENARIOS.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
RECENT GUIDANCE ALL TRACKS A SURFACE COLD/OCCLUDED FRONT THROUGH
CENTRAL PA WED NIGHT IN ADVANCE OF AN UPPER LOW APPROACHING
FROM THE GRT LKS. STRONG LARGE SCALE FORCING AHEAD OF THE UPPER
LOW AND LOW LEVEL CONVERGENCE ALONG THE FRONT SUPPORTS A HIGH
CHANCE OF RAIN SHOWERS WED NIGHT. HOWEVER, PLENTY OF SPREAD
REMAINS WITH REGARD TO RAIN AMOUNTS. ENSEMBLE MEAN QPF IS IN THE
0.25 TO 0.60 INCH RANGE. HOWEVER, A DECENT NUMBER OF EPS
MEMBERS PRODUCE TOTALS >1 INCH ASSOCIATED WITH THE POTENTIAL OF
DEEPER GOMEX MOISTURE STREAMING NORTH AHEAD OF THE FRONT.
CURRENT GUIDANCE INDICATES A DRY SLOT WILL WORK INTO CENTRAL PA
THU MORNING, THEN A PERIOD OF CHILLY AND UNSETTLED WEATHER LOOKS
VERY LIKELY LATE THIS WEEK, AS THE UPPER LOW TRACKS ACROSS OR
JUST NORTH OF PA. A DEEP MOIST NORTHWEST FLOW ON THE WESTERN
PERIPHERY OF THE EXITING UPPER LOW SHOULD RESULT IN PERSISTENT
LAKE-ENHANCED, OROGRAPHIC PRECIPITATION FOCUSED OVER THE W MTNS
THURSDAY NIGHT INTO AT LEAST THE FIRST HALF OF NEXT WEEKEND.
MODEL THERMAL PROFILES CURRENTLY LOOK COLD ENOUGH TO SUPPORT THE
FIRST ACCUMULATING SNOW OF THE SEASON ACROSS THE HIGHER
ELEVATIONS OF THE ALLEGHENIES BETWEEN THU NIGHT AND SATURDAY,
BUT SNOWFLAKES COULD EXTEND SOUTHEAST OF THE ALLEGHENY FRONT AT
TIMES.
IN ADDITION TO FREQUENT PRECIPITATION AND BELOW NORMAL DAYTIME
TEMPERATURES, GUSTY WEST-NORTHWEST WINDS ARE ALSO ANTICIPATED
FRIDAY AND SATURDAY, AS A TIGHT GRADIENT DEVELOPS WEST OF AN
INTENSIFYING SURFACE LOW OVER EASTERN NEW ENGLAND. LATEST EPS
PLUMES INDICATE GUSTS OF 30-35MPH ARE LIKELY BOTH DAYS.
PERSISTENT CLOUD COVER AND COOLER TEMPERATURES ALOFT WILL KEEP
HIGH TEMPERATURES IN THE UPPER 30S TO NEAR 50F, WHICH WILL BE A
SIGNIFICANT CHANGE, BUT IS STILL ONLY A FEW DEGREES BELOW
NORMAL FOR THIS TIME OF YEAR.
AVIATION /04Z MONDAY THROUGH FRIDAY/
HIGH CLOUDS CONTINUE TO STREAM ACROSS THE AIRSPACE THIS EVENING.
EXPECT LOWERING CEILINGS THROUGHOUT THE NIGHT ACROSS THE WESTERN
HALF OF THE STATE IN CONJUNCTION WITH A WEAK COLD FRONT. AS OF
THE 00Z GUIDANCE MVFR IS ONLY ANTICIPATED AT BFD AND JST.
INITIAL MVFR RESTRICTIONS ARE PROGGED BY A COMBINATION OF
GLAMP/RAP GUIDANCE TOWARDS THE 07-08Z TIMEFRAME AT BFD, ALTHOUGH
THERE REMAINS A SMALL POSSIBILITY THAT THE LOW LEVEL CLOUDS
COULD ARRIVE SLIGHTLY EARLIER. THERE WILL ALSO REMAIN A PERIOD
WHERE CEILINGS COULD (~30-40% PROBABILITY) DIP BETWEEN 700 AND
1000FT AGL OUTLINED IN BEST IN THE 00Z/12Z HREF AT BFD;
CONFIDENCE IS SLIGHTLY HIGHER IN IFR CIGS OCCURRING FOR A BRIEF
TIME AT BFD THIS MORNING.
AT OTHER WESTERN AIRFIELDS (JST/AOO/UNV), MODEL GUIDANCE DOES
SHOW FAIRLY GOOD AGREEMENT WITH RESPECT TO CEILINGS LOWERING
TOWARDS MVFR THRESHOLDS AT JST, WITH LESS SIGNALS IN MVFR
CEILINGS PREVAILING AT AOO/UNV. AS OF THIS TAF PACKAGE VFR IS
THE MOST LIKELY SOLUTION. AFTER SUNRISE ON MONDAY, GENERALLY
EXPECT SCATTERING OUT OF THE LOWER- LEVEL CLOUD DECK QUICKLY
ACROSS EASTERN PENNSYLVANIA. SOME RESIDUAL LOW- LEVEL CLOUDS
WILL REMAIN AT JST/BFD, WITH THE BULK OF MODEL GUIDANCE
GENERALLY HOLDING ONTO LOW CEILINGS UNTIL THE 16-17Z MONDAY
TIMEFRAME.
IT IS WORTH NOTING THAT WHILE NO LLWS MENTIONS WERE MADE IN
THIS TAF PACKAGE THERE IS A SIGNAL FOR INCREASING LOW- LEVEL
WINDS ON THE LEEWARD SIDE OF THE ALLEGHENY MOUNTAINS AHEAD OF
A SHORTWAVE AT 850MB. WINDS ARE LIKELY TO REMAIN BELOW LLWS
CRITERIA, BUT AOO/UNV STILL HAVE A CHANCE (~20%) TO GET CLOSE
FOR A FEW HOURS AFTER 05Z.
OUTLOOK...
TUE...MAINLY DRY WITH VFR CONDITIONS.
WED...RESTRICTIONS POSS, MAINLY NW. MORE WIDESPREAD
RESTRICTIONS WITH RAIN AND LLWS WED NIGHT.
THU-FRI...RESTRICTIONS LIKELY WITH RAIN AND SNOW SHOWERS.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD/BANGHOFF
LONG TERM...FITZGERALD/BANGHOFF
AVIATION...NPB/BOWEN
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