textproduct: State College

SYNOPSIS

* Dry weather is expected to continue through the middle of next week, featuring cool nights, and warm comfortable afternoons * Frost possible again Sunday morning in northern PA. * Next chance for rain comes Thursday and Friday with a cold front.

NEAR TERM /THROUGH TONIGHT/

Fog forming in the river/stream valleys. Expect it to last into the mid- morning where it is most-dense. A couple of backyard/meso obs are into the 30s, now, mainly right where the frost advy is (McKean Co). So, temps are on track.

Expansive high pressure centered over the Great Lakes is dominating our weather pattern again today, and will for the next 3 days as it slowly migrates east. A patch of high, thin cirrus over nrn PA will drop down across Central PA today, and some diurnal cu are expected (mainly NE). But, it will be another dry and mild day with wording of mostly sunny excellent to describe the sky. Max temps today should be 6-10F warmer in the NW vs Saturday, and 2-3F warmer in the SE. That puts us very nearly normal on highs across the entire CWA.

SHORT TERM /MONDAY THROUGH MONDAY NIGHT/

More good news for those wanting to be outdoors, and if you like saving money on your heating/cooling bills. The high pressure centered just to our N will continue to slide E. Expect only fair-weather clouds for the end of the Labor Day weekend. Some fog is again possible in the cooler valleys of the N tonight and Monday night. There should be more cu on Monday vs the last few days. Middle of the road NBM temps are looking good. Might have to add more cu to Monday aftn fcst based on moisture profiles from deterministic model moisture plots. Did not make any notable adjustments at this point.

LONG TERM /TUESDAY THROUGH SATURDAY/

3 AM Update... Biggest concern with the long range is the probability of precip for the Thursday-Thursday Night period when a cold front is slated to pass through. NBM guidance has a solid grasp of the period of highest probability being Thurs and Thurs night. Deterministic ECMWF is the outlier at this point by developing a wave along the front as it works thru Central PA, delaying FROPA and prolonging higher rain chances versus most other models and ensembles. Next weekend may not be entirely dry, but the front should be to our east before Saturday and our chcs for rain drop to below 20 pct.

Prev... The upper-level, synoptic-scale configuration looks to feature a transition towards an amplified pattern, with a building western North American ridge axis, a deepening Great Lakes and Midwestern trough axis, and a western Atlantic ridge. Given consistency of our ensemble prediction systems in showing this pattern, confidence is relatively high.

At the beginning of the period (Tuesday and Wednesday), with a deep layer of dry air still in place and continued moderation of daytime highs over time, minimum afternoon RH values will dip. By Wednesday, we may also see increasing SW winds in the boundary layer, as surface high pressure starts to push eastward off the coast. In fact, on Wednesday, ensemble probabilities for combined sub-30% RH and wind gusts of greater than 20 mph are locally 30-40%. Thus, we may have to watch fire weather parameters more closely by Wednesday, particularly given our lack of rainfall for much of the Commonwealth in the last 2-4 weeks.

Later in the week, it is anticipated that the lower-level flow will turn more southerly and bring increased moisture into the region. Also, with an approaching cold front from the northwest and deepening troughing aloft upstream (mentioned above), the chances for showers should increase.

AVIATION /11Z SUNDAY THROUGH THURSDAY/

VFR conditions are virtually certain (100% confidence) through 12Z Monday under the influence of high pressure. Model guidance is in fair agreement with respect to scattered low-level clouds across much of central Pennsylvania this afternoon with high clouds working into the Lower Susquehanna Valley (MDT/LNS) after sunset. Fog formation looks less likely after 06Z Monday compared to previous evenings with HREF/RAP model guidance outlining less low-level moisture.

Outlook...

Mon-Tue...AM valley fog possible; otherwise predominantly VFR.

Wed...Isolated SHRA possible in the afternoon across the far west at locations such as BFD and JST.

Thu...Widespread SHRA

CTP WATCHES/WARNINGS/ADVISORIES

None.