textproduct: State College

SYNOPSIS

* Quick shot of light snow across the northern tier Monday AM * Pattern shift will bring an early January thaw to CPA with a substantial warming trend/above normal temperatures Tue-Sat * Best odds for rain are Tuesday & Friday/Saturday; breezy conditions late week followed by noticeable cooldown Sun/Mon

NEAR TERM /UNTIL 6 AM MONDAY MORNING/

Low clouds holding firm across the NW 3/4 of the CWA should be persistent under the inversion this evening and tonight, while mid and high level clouds spread across CPA into early Monday morning in advance of fast-moving/low amplitude shortwave moving across the Great Lakes. Tried to lean a bit warmer vs. NBM based on extended cloud cover.

Surge of low-mid level WAA downstream of the aforementioned shortwave will likely spread a quick 6-12hr period of snow across the northern tier late tonight into early Monday morning. The best QPF signal is located to the norther of the PA/NY border; however hires ensemble guidance supports 0.5-1.0" snow particularly along and to the north of the US-6 corridor. Time of arrival suggests some travel impacts/delays are possible across the northern tier. Some light snow could extend as far south as I-80, but again much higher odds for snow accum closer to the NY border.

SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/

Brief period of WAA quickly shifts to the east/northeast by 18Z Monday. The rest of Monday looks mostly cloudy and not as cold with max temps +10-15 degrees warmer than Sunday over the western half of the forecast area.

Attention shifts upstream Monday night as a stronger shortwave pivoting over the Great Lakes sends a sub-1000mb sfc low from Chicago to Buffalo. Expect another bout of WAA precip, but with much warmer thermal profiles. The 04/12Z hires and global models trended slower with the onset of precip Tuesday morning; which seems to mesh with fcst sounding profiles around BFD showing a dry layer aloft. It appears by the time precip reaches the CWA (closer to 18z than 12z, temps will probably be too warm at the sfc to support much zr. We can't rule out some pockets of zr Tuesday morning, but the overall trend has been toward a declining risk. Periods of rain continue into Tuesday night and could mix with wet snow over the western mtns.

Winds should increase Tuesday night on the back side of the low as reaches the Gulf of Maine. Widespread gusts 25-35 mph are possible into early Wednesday morning and later shifts may need to ratchet gusts higher.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Breezy start Wednesday; otherwise mild and drying out but staying mostly cloudy as low stratus/stratocu get trapped beneath the inversion associated with high pressure building over the area. Highs Wednesday are fcst to be 10-15F above the historical average in the 35-50F range (NW-SE).

Warming trend ramps up Thursday into the weekend. This will be the peak of the early January thaw. Max temps are projected to be 10-20 degrees above normal for early January in the 45-55F range. It will also be a fairly wet period from Thursday night into the weekend with broad SW flow aloft and hi pwats surging into the area in advance of an occluding low and slow moving cold front.

Bulk of the QPF is focused over NW PA; there is some concern that the rain combined with snowmelt/ice jams could result in some minor flooding. Risk is low, but something to be monitored in the coming days. Ice jam risk may be elevated elsewhere due to melting snowpack, increased streamflows and unseasonably mild stretch of warmth.

Beyond the long term period, the pattern looks to mean revert and cool down (behind the cold front) back to levels more typical of mid-January by early next week.

AVIATION /00Z MONDAY THROUGH FRIDAY/

An expansive stratus deck remains in place over Central PA this evening, resulting in IFR ceilings at BFD and JST, and MVFR ceilings at AOO and UNV. Areas farther to the east are VFR. The stratus will shrink through the night from southeast to northwest as high pressure builds in and all TAF sites will likely be VFR by 15Z.

A clipper system will bring light snow to the northern half of Pennsylvania late tonight and into the early morning, with BFD most likely to see visibility restrictions. There is a small chance (< 30 percent) of restrictions developing at IPT and UNV as well. Snow pushes off to the east by 15Z and dry weather is expected for the rest of the day with varying amounts of mid and high level clouds. Winds will be out of the south at 5 to 10 knots.

Outlook...

Tue-Wed...Restrictions possible in the N/W, light rain possible

Thu...Mainly VFR.

Fri...Restrictions with a batch of steady rain.

CTP WATCHES/WARNINGS/ADVISORIES

None.