textproduct: State College

WHAT HAS CHANGED

* Added discussion about front timing on Sunday and its impact on observed high temperatures.

KEY MESSAGES

1) Temperatures start a steady climb today with a couple chances for light precipitation through Friday.

2) Cold frontal passage Sunday should make widespread rain showers perhaps ending as a brief period of snow across the north.

DISCUSSION

KEY MESSAGE 1: Temperatures start a steady climb today with a couple chances for light precipitation through Friday.

High pressure will reside overhead today and start to slide to the east tonight. A warm front is expected to generate meager lift, but the western mountains and that lift may squeeze out a little light snow there tonight. Most everyone else should just be cloudy. Any accumulations will be less than an inch, and that would be most possible (40%) over Warren/McKean/Elk counties. The 8H temps rise about 6C through the day, and help us get about 8F warmer than Tuesday.

A compact Clipper will drop down from WI/MI, and generate a meager attempt at generating precip Thursday aftn and evening. Most models have temps warm enough at that time to keep it rain, but the NE may have a mix/elevation snow. Still, the QPF is <0.10, so any eventual accums on the grassy areas will be <1". The PoPs will be highest (30s) in the N and SW. We may want to eventually bump these PoPs up, but model consensus in precip occurrence is low at this time. Add 8-10F onto maxes from Wed.

The atmosphere tries one more time to make light precip before the start of the day Saturday (starting late Fri). This one looks like the best chance (60-70 PoPs) of these three attempts at precip. Despite dropping down from farther north than the previous attempt, the sfc low deepens more, and the tap of moisture from the S will be better, too. Generally <0.25" QPF is seen as it crosses PA late Friday and Friday night. Again, temps will be plenty warm enough for all rain. Since it will be more energetic than Thursday's shot, there will be a slight/chc for TS across the SW. But, no worries for severe at this time. Maxes should be another 6-10F warmer than the day before.

---------------------------------- KEY MESSAGE 2: Cold frontal passage Sunday should make widespread rain showers perhaps ending as a brief period of snow across the north.

Most of Sat will be dry outside of a lingering morning SHRA in the east. Temps warm a little more with 50-55F numbers across the northern tier and 55-65F elsewhere. A couple of places in the southern tier could take a run at 70F on Sunday before a cold front brings clouds and numerous SHRA. Timing and orientation of the front is a little unclear at this time, but most models agree on the cold air getting into PA before the end of the night/Monday morning. As Sunday approaches, it is likely that temperatures across the south will trend higher, while temperatures in the north could end up a bit lower. In the most optimistic case, highs in the upper 70s are possible in the south (Canadian GEM). A faster frontal passage could keep temps stuck in the 50s there (as depicted by the GEFS).

By Monday morning temps should be in the 20s across the north. That drastic change will take place while precip may be falling Sunday night. So, there should be some mix/snow at the end of the precip. It should be generally minor, with probs of 3"+ of snow 20pct in the far N and nil elsewhere. It is also worth noting that Wednesday morning's low temperatures (upper single digits to mid 20s) may be the coldest we experience until November. Barring another accumulating snow followed by a stretch of clear nights, such cold temperatures will be tough to achieve based on the expected pattern upcoming.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Overcast skies tonight with light winds will be the story for the beginning of this TAF package. Overall ceilings should remain VFR with broken to overcast clouds between 5,000 and 10,000 ft. The usual spots of lower cloud heights are being observed at BFD and JST. These two sites will largely remain MVFR through today and into tonight. Occasional isolated snowshowers off Lake Erie could cause additional restrictions at BFD, but confidence in these impacts remains less than 50%.

Clouds will remain overcast throughout the day today thanks to a weak passing warm front bringing just enough moisture to prevent any scattering of the cloud deck. Persistent MVFR is expected over western Pennsylvania, while elsewhere clouds should remain borderline VFR near 4,000 ft. Conditions outside of lake effect snow will remain dry through Friday.

Outlook...

Thu PM...Lingering MVFR ceilings north and west. Fri..Mainly VFR. Friday Night...Restrictions in rain showers. Sat-Sun...Mainly VFR. Sun Night - Mon...Cold front passage, restrictions in rain; some wintry mix possible across the north.

CTP WATCHES/WARNINGS/ADVISORIES

None.