textproduct: State College

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1) Pleasant, uneventful early Fall weather to persist into the first part of the weekend.

2) Rain chances increase Sunday into Monday, as the remnants of Isaias quickly move through the Commonwealth.

DISCUSSION

KEY MESSAGE 1: Pleasant, uneventful early Fall weather to persist into the first part of the weekend.

Other than a narrow band of mid-level clouds crossing the Commonwealth, another sunny afternoon is in progress. This will lead into a mainly clear start to the evening.

Later tonight, a fairly moisture-starved surface cold front will make its way across the state. Although some cloudiness is expected to accompany this system, little to nothing in the way of shower activity is anticipated.

Thursday should be a breezy and seasonably cool day behind the aforementioned frontal system, but rain-free.

Friday and Saturday should remain dry, as a narrow ridge of surface high pressure translates across the Commonwealth. By Saturday, temperatures should begin to rebound, as low-level warm advection ensues. Highs Saturday afternoon should range from the upper 60s over the higher terrain, to the mid-upper 70s in the Susquehanna Valley.

------------------------------------------------------------- KEY MESSAGE 2: Rain chances increase Sunday into Monday, as the remnants of Isaias quickly move through the Commonwealth.

Our ensemble prediction systems remain fairly consistent in showing a quick eastward movement of Isaias' remnants and associated moisture from the OH Valley across the Mid-Atlantic from later this weekend into early Monday. From this early vantage point, it looks like the most persistent/concentrated rainfall across Central PA will be centered on the Sunday afternoon to Sunday night period. Initial indications are that a combination of a short time window for heavier rainfall (most likely 12-18 hours, perhaps even less), plus a welcome recent stretch of drier conditions, should significantly mitigate the potential for sustained heavy rainfall/flooding. That being said, we'll continue to watch the progress of this system closely over the coming days.

At this time, it looks like improving weather can be expected with time on Monday.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

18z update... VFR/unrestricted conditions should persist through at least the evening hours.

Overnight, as a cold front crosses PA, we're monitoring three potential sources of impact: 1) Possible lower clouds over the Alleghenies just ahead of and behind the front, 2) Probable low-level shear ahead of the front, and 3) At least a low probability of early morning fog in the vicinity of KIPT, just ahead of and near the time of frontal passage.

Regarding item 1, we've indicated MVFR-fuel alternate restrictions for a time at KBFD and KJST. At this early vantage point, IFR restrictions look unlikely. For item 2, low-level wind shear was introduced for all terminals except KMDT and KLNS, as we generally expect the band of stronger winds just above the surface boundary layer to weaken as it comes into eastern PA during the pre-dawn hours. For item 3, this is a tough call for KIPT. At this juncture, our gut feeling is that stronger winds just off the deck will mitigate the potential for fog development. Thus, we trailed back on this mention to just call for brief MVFR restrictions. Right now, we'd estimate the probability of IFR restrictions at KIPT early tomorrow at around 20%. We'll continue to monitor that situation during the evening and overnight hours.

On Thursday, strong dry advection post-frontal passage should lead to VFR conditions area-wide. Thursday's main sensible weather impact should be gusty W-NW winds (generally gusts of 20-25 kt area-wide, with occasional gusts around 30 kt in the Lower Susquehanna Valley).

Outlook...

Fri-Sat... VFR conditions expected.

Sun-Mon... Restrictions likely in lower ceilings and rain.

CTP WATCHES/WARNINGS/ADVISORIES

None.