textproduct: State College

WHAT HAS CHANGED

* Introduced a bit more in the way of valley fog for early Tuesday and Wednesday mornings.

KEY MESSAGES

1) Unseasonably mild and dry weather will continue until late Wednesday Night.

2) Periods of showers preceding and accompanying a cold frontal passage. Cooler and a return to mainly dry conditions will follow for Friday through Sunday.

DISCUSSION

KEY MESSAGE 1: Unseasonably mild and dry weather will continue until late Wednesday Night.

The close proximity of a surface high to our southeast will keep winds light from the SE or South and weather tranquil until Wednesday. A sprinkle isn't out of the question later tonight into tomorrow in the northern tier of counties but any appreciable precipitation looks to remain north of the NY border.

Upper level ridging builds back into the region for the first half of this week, helping to prolong our dry stretch and keeping temperatures 10 to 15 degrees above normal for much of week. Highs in the lower 70s are in store for all but the higher elevations on Wed. As a weakening low pressure system approached from the west along with an upper level closed low, the tightening pressure gradient may allow for stronger southerly winds on Wednesday.

KEY MESSAGE 2: Periods of showers preceding and accompanying a cold frontal passage. Cooler and a return to mainly dry conditions will follow for Friday through Sunday.

Chances for widespread rainfall return for the second half of the week. Very late Wed night is the earliest anyone will see precip as a complex system develops over the middle of the country. There is still uncertainty regarding exactly how this system pans out with a few phasing jets to keep track of. The theme in this morning's solutions was the vertical stacking that became apparent as this system moves towards us. The main surface low moves under the center of the upper level low before impacting us and begins to weaken/occlude as it loses the best ascent. With a possibly more diffuse, but still apparent, boundary a more stratiform precipitation mode may be favored with a few heavier pockets possible.

GFS and ECMWF disagree on the degree of how far a shortwave trough swings down from Canada on Friday. Should a more progressive solution develop, this may sweep through another cold front and round of precipitation Friday into Saturday. Regardless, long range guidance hints at cooler temperatures this weekend trending more seasonable with dry conditions on the back of the weekend.

AVIATION /08Z TUESDAY THROUGH SATURDAY/

VFR will continue at all Central PA and Susq Valley airfields through the rest of the overnight hours and Tuesday with variable amounts of the mid-level altocumulus clouds based between 8000 and 11000FT AGL.

The lone exception will be INVOF of KBFD where the nose of a low level moist axis was aimed right at the NW Mtns of PA and Erie Lakeshore with MVFR CIGS there. Cigs will gradually rise into low end VFR at KBFD by 15Z today with VFR continuing elsewhere.

The next chance for impactful precipitation will arrive Wednesday evening (NW) and overnight into Thursday across the Central and Eastern part of the CWA.

Low pressure will track NE from the Central Plains and reach the Upper Great Lakes Wednesday evening. Strengthening southerly flow ahead of the low's southward trailing cold front will create a moderately gusty southerly flow over the western half of PA Wednesday and Wed night with a 12-15 hour period of LLWS later Wednesday into the mid morning hours Tuesday.

Outlook...

Wed-Thu...Rain showers, especially in the PM hours on Wednesday and continuing into Thursday. Sub-VFR conditions become more likely in showers.

Fri-Sat...Scattered to isolated rain, cloudy conditions and sub VFR ceilings possible.

CTP WATCHES/WARNINGS/ADVISORIES

None.