NEAR TERM /UNTIL 6 PM THIS EVENING/
MRMS and surface obs early this morning showed a few bands of light rain pushing NWWD across the CWA and dissipating as they approached the deeper/dry air in the lowest 7-8 kft AGL near and to the north of Interstate 80.

We're seeing a milder start compared to recent days with daybreak temps ranging from the low and mid 50s over the northern tier, to the low and mid 60s in the Lower Susq Valley.

Another few rounds of rain are expected later this morning and this afternoon over the southern third of the state, where 2-3 tenths of an inch are possible by dusk. Locally higher amounts near 0.50 of an inch are possible over the southern tier counties, where some models indicate a bit of elevated instability and the potential of a deeper warm cloud layer and heavier showers in the 12-18Z time frame.

Elsewhere across Central and Northern PA, rainfall amounts will be minimal, but widespread and generally thick mid level clouds will persist with a light East to ENE breeze.

Afternoon highs today will be coolest (low to mid 60s) across the Laurel Highlands and mainly between 70-75 degrees over the remainder of the CWA

SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/
The weak surface low off of the NC coast is progged to drift northeast and out to sea tonight through the week's end.

This will cause the low level flow to gradually back from the ESE to the Northeast, allowing drier air to advect into the much of the CWA late today and tonight.

An increasingly northerly flow should dry things out Thursday into Friday. However, a few bands of enhanced mid-level FGEN forcing just to the NW of the 1008 mb sfc low east of KACY will help to focus the best chc for rain near and to the SE of the I-81 corridor later tonight through Thursday night where an additional few tenths of rain are expected.

Elsewhere, partial clearing of the mid and high cloud layer is expected with just a few sprinkles or a stray brief shower possible. Model RH profiles support an increasing amounts of sunshine Thursday into Friday across much of Central and NW PA.
GEFS 850mb and surface temps indicate a return to above normal afternoon readings.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
Higher confidence in dry wx/no rainfall particularly early in the period (through the upcoming weekend) thanks to deep layer ridge pattern at the sfc and aloft. While model variability remains elevated into next week, the ensemble means generally favor weak upper troughing centered around the Great Lakes which will support a marginal increase in rainfall/shower potential along/ahead of an approaching front by next Monday or Tuesday.
Forecast max temps 75-80F peak +5-10F above mid/late September climo to start the weekend and trend modestly cooler to 65-75F (near the historical average) into early next week.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
MVFR ceilings at MDT with -SHRA with otherwise VFR conditions prevailing as of 10Z observations. Rain showers originally progged to go into JST have mostly fallen apart so have limited VCSH mentions until closer to 13-14Z. GLAMP guidance continues to go heavy on the low-level clouds and given model agreement can see a period between 13Z-16Z where JST/AOO experience lower ceilings with slightly higher confidence in the 14Z-16Z timeframe. RAP model soundings continue to outline this threat longer into 20Z which matches fairly well with GLAMP guidance so have continued restrictions through ~20Z Wednesday at these airfields.

Showers closer to MDT/LNS will remain scattered this morning so have mainly left mentions to VCSH with lower ceilings in the near-term through 17Z where the best chances for rainfall will be today. Model guidance has hinted that -SHRA/-RA will return later in the afternoon/evening at MDT/LNS; however, there is lower confidence in this solution with some model spread. The 12Z TAF package does not make overly explicit mentions of showers, even in the form of VCSH, at MDT due to increased uncertainty here but have outlined VCSH at LNS due to closer proximity to moisture.

For airfields further north (BFD/IPT/UNV) have limited precipitation mentions to UNV throughout the TAF period as there is considerable uncertainty on rainfall pushing closer to the Interstate 80 corridor. GLAMP guidance suggests MVFR ceilings at UNV from 12Z-20Z; however, RAP model soundings suggest slightly less clouds cover in the lower-levels so have kept cloud bases slightly below MVFR thresholds in a targeted timeframe between 16-18Z, where -SHRA might trek closer to the airfield. In the overnight period (00Z-12Z Thursday), GLAMP guidance suggests fog formation at BFD/IPT but given some cloud cover and light winds have decided to keep these restrictions out of the TAF.

Outlook...

Thu...MVFR cigs possible in the southern and eastern portions of the airspace.

Fri-Sun...Valley fog in the morning; otherwise VFR/no sig wx.

CLIMATE
The first day of Autumn 2024 (Fall Equinox) begins at 8:44 am EDT on September 22nd.

CTP WATCHES/WARNINGS/ADVISORIES
None.