textproduct: State College

WHAT HAS CHANGED

* Decreased MaxT (today) and MinT (tonight) given expansive cloud cover across the northern tier. * Slightly cooler trend to the forecast for the latter half of the week, details still to be ironed out ahead of the potential first accumulating snowfall of the season.

KEY MESSAGES

1) Tranquil weather expected with above-average temperatures expected through Wednesday evening.

2) Potential for the first accumulating snowfall of the season, especially across the Laurels and the northern tier of Pennsylvania.

DISCUSSION

KEY MESSAGE 1: Tranquil weather expected with above-average temperatures expected through Wednesday evening.

Current (2:00 PM EST) radar outlines light returns expanding along a line from UNV to FIG; however, observations at the airfields outline little (if any) precipitation falling at the sites. Given the low-level dry air in place, generally expect very little rainfall throughout the rest of the evening. If any rain is to fall, it will generally be light and not even enough to wet the ground, so have low PoPs in for this timeframe. This will begin a stretch of dry weather that is expected to continue through Wednesday as a surface ridge works into the region. This will also supply the region with above-average temperatures through Wednesday evening. The main weather concern will continue to be breezy winds through Wednesday given the low pressure system in western Quebec and high pressure across the Lower Ohio Valley bringing a tightening pressure gradient across the region. Maximum wind gusts (30-40 mph across the highest elevations of the Laurels) will be occurring during the afternoon hours today and tomorrow.

KEY MESSAGE 2: Potential for the first accumulating snowfall of the season, especially across the Laurels and the northern tier of Pennsylvania.

The main focus of the forecast period will be the potential for the first accumulating snowfall across portions of central Pennsylvania in the latter half of the week. Initially, chances for precipitation begin to ramp up Wednesday morning ahead of an approaching low pressure system moves into the region from the Mid-Ohio Valley. Temperatures at onset are expected to be in the mid-to-upper 30s across the northern tier and likely continue to trend warmer (even slightly) throughout the daytime. It is expected that temperatures will trend cooler after sunset; however, current forecast outlines lowest temperatures remaining above freezing given the considerable cloud cover across the region. If anywhere is to observe some wet snowflakes overnight Wednesday night into Thursday, it would likely be across McKean County; however, confidence remains too low so have retained rain mentions in this forecast cycle.

All ensemble guidance points towards colder air working into the region Thursday night into Friday, which could bring the first accumulating snowfall to portions of central Pennsylvania. During the daytime hours on Thursday, temperatures at 850mb range from +2 to +4C before trending closer to the -3C to -5C range, outlining the extent of cooler air is working into the region with this system. This will likely allow for a transition to outright snow showers Thursday evening across portions of northwestern Pennsylvania and the Laurel Highlands where temperatures are expected to be much cooler than surrounding locations. Gradual mixing will likely continue into sunrise on Friday with areas generally north/west of the I-80/I-99 corridor experiencing some potential for snow for the Friday morning commute. There remains a bit of uncertainty with respect to the daytime forecast of Friday with more recent NBM model guidance trending slightly cooler compared to previous runs. This has led to a slight increase in the snowfall footprint compared to the previous forecast cycle. As this low pressure shifts further east, breezy northwesterly flow begins to take hold on the region late Friday and into Saturday which is expected to begin producing lake-enhanced snow showers downwind of the Great Lakes. Forecast could change with respect to this depending on the exact wind direction; however, additional snow showers will be possible for the first half of the weekend.

Given the set-up late Thursday through the first half of the weekend and the uncertainties still in play with respect to the snowfall/rain forecast, we urge folks to continue to monitor the forecast. Given the signal for colder air in the region and given the climatology across the region, some portions of the area (most likely in the higher elevations of the Laurels and across the northern tier of Pennsylvania) are likely to see some snowflakes with this approaching system. The first accumulating snowfall across the region typically catches folks off guard, but keep in mind that we're getting into the middle of November where it will only become more likely that accumulating snowfall will occur across the region. Take time to look over winter plans, whether it is for your home and/or car as we continue to transition into winter across the region.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Typical post-frontal and lake-enhanced stratocu will continue to thin/break up into the evening. Will keep the clouds mvfr longer at BFD than JST. Gradient slackens and sfc wind backs overnight. Eastern sites go light. Low level jet may be just strong enough as a warm front moves across the area to make LLWS for 3-6 hrs at the 4 western terminals. A quick-moving short-wave trough zips by Tuesday, picking up the wind again, but they should not be quite as gusty as today/Monday. Very similar conditions with variable clouds - mainly VFR - are expected Tues & Wed.

Outlook...

Wed PM-Thu...Conditions deteriorating to IFR and spotty LIFR clouds, -RA, FG.

Fri...IFR clouds. -SHRA turning to -SHSNRA. LIFR, mainly N & W. Gusty NW flow.

Fri PM...-SHSN, occnl IFR NW. -SHRA, MVFR SE. Gusty NW wind.

Sat...Improving, but still gusty with MVFR clouds BFD/JST. VFR elsewhere.

CTP WATCHES/WARNINGS/ADVISORIES

None.