textproduct: State College

WHAT HAS CHANGED

* Tweaked precip type on Monday/Mon night with more snow vs rain N of I-80. * Increased sky cover in near term due to solid low deck over the SE/Ern counties.

KEY MESSAGES

1) Cold front moves through this morning. 2) Light snow likely across the northern tier Monday/Monday night. 3) Much colder next week but warming up again at week's end.

DISCUSSION

KEY MESSAGE 1: Cold front moves through this morning.

Rain showers are along and surrounding a potent cold front over western PA at 07Z. The broad rain band still has some moderately heavy rain elements embedded, but overall, the rain is light. Gusts with the frontal passage are in 30-35KT at times. While these speeds/gusts will persist for the time the rain is crossing the CWA this morning, the gusts should generally top out in the 20s during most of the day. With the cold advection dropping the temps for most of the day (except in the SE where they may add a few degs F onto the sunrise temps), it could feel rather raw. Most places will be dry after the main rain band passes (13Z JST/UNV, 16Z MDT). But...

By noon, sct SHRA return to the NW mtns. As the temps in the clouds and at the sfc get colder, the precip will become frozen and have little time/altitude above freezing to melt on it's way to the ground. There could also be a little graupel in a shower or two if they can tap a little CAPE. These SHSN will last into the first half of the night. Just a dusting of an accum is expected, mainly along and N of Route 6.

---------------------------------------

KEY MESSAGE 2: Light snow likely across the northern tier Monday/Monday night.

A Clipper-like system dives down from Central Canada and across the Great Lakes on Monday. It has meager moisture to drop on Central PA, but numerous SHSN expected in the northern tier. More sparse showers (mixed) will make it south of I-80. Sfc temps are expected to get into the 40-45F range in the nrn tier in the aftn on Mon, so the p-type may be a mix, too. The NAM does paint some meager CAPE in the NW, too. So, there could be a briefly heavier spot of precip/snow here and there. At this point, it doesn't look dynamic enough to make serious snow squalls. However, the forcing looks strongest later in the day and evening Monday as a short wave trough passes overhead. A couple of models show the SHSN dipping into the Laurels in the evening. The SHSN will linger all night and perhaps into Tuesday AM until the (broad) axis of the upper trough moves past the CWA. Overall, the accums could be an inch or so in the nrn tier and perhaps a dusting in the Laurels and Alleghenies. Wouldn't be surprised to see a dusting on the ridge tops around Happy Vally by Tuesday AM.

---------------------------------------

KEY MESSAGE 3: Much colder next week but warming up again at week's end.

Tuesday MA mins will be cold enough for frost over all of the area, but wind of 10-15 G 20-25KT will keep that from happening. The cold pool will be deepest on Tuesday, limiting max temps to the freezing mark near the NY border and 45-50F in the srn cities. These numbers will be about 10-12F below normals.

Wednesday morning will be the coldest this week due to the center of the sfc high being right overhead. Morning mins will be well below freezing everywhere. Even the Lower Susq will get into the L-M20s. The start of the growing season (date of the normal last spring freeze) is not until the 11th there. So, we probably won't be issuing frost/freeze products for that morning. But, collaboration with our neighboring WFOs will weigh heavily on that decision.

It then warms up close to normals maxes on Wed as the sfc high slides to our E and S and the wind turns to come out of the S and we should be sunny. Thursday looks much warmer, jumping another 10-15F over Wed's numbers. PoPs stay pretty low as we warm up as the sfc high noses back into the Deep South. That will help to keep moisture from the Gulf from getting to us.

AVIATION /07Z SUNDAY THROUGH THURSDAY/

Flight restrictions to LIFR are underway across our Lower Susquehanna Valley terminals (KMDT/KLNS), where cool/moist maritime air has settled in behind a backdoor cold front. Lesser flight restrictions to MVFR are being observed along the leading edge of this shallow cool air mass (e.g KIPT), where ceilings are closer to 1500 ft. Eastward progression of this front has stalled as of 06Z, with KUNV located just outside of this wedge of cool/moist air. Strengthening southerly flow ahead of the primary cold front to our west will gradually erode the maritime air along its southern edge, with improvements to IFR being likely (70% chance) at KLNS/KMDT around 12Z.

Meanwhile, the primary cold front and its associated rain showers are bringing MVFR to IFR conditions at KBFD, with transient IFR visibilities observed in the heavier rain showers. Flight restrictions associated with this front are expected to impact our central terminals (KJST/KAOO/KUNV/KIPT) between 08-15Z, and our Lower Susquehanna Valley terminals from 13-19Z. The probability for thunder remains too low for PROB30 mentions at this time, with 07Z SPC Mesoanalysis showing <100 J/kg of MUCAPE regionwide. With that said, 00Z HREF mean MUCAPE shows values increasing to around 100-250 J/kg across KMDT/KLNS during the frontal passage, though uncertainty regarding storm coverage/likelihood precludes thunder mentions at this time. Otherwise, LLWS remains a concern overnight, with mentions at all terminals ahead of the front where wind shear is maximized.

VFR is expected to prevail for most sites by 19Z Sunday, except for MVFR being moderately likely (40-50%) to persist across KBFD/KJST through the end of the TAF package, where an MVFR stratocumulus deck is favored given upslope winds west of the Alleghenies and flow off the Great Lakes. Moreover, rain/snow showers may develop across KBFD/KJST as low-level lapse rates steepen behind the front during the afternoon, with coverage being greatest (30-50%) between 21Z-03Z based on the HREF.

Outlook...

Mon...Breezy and cooler with MVFR N/W and VFR elsewhere, with scattered rain/snow showers possible.

Tue...Mainly VFR with a few rain/show showers.

Wed-Thu...VFR.

CLIMATE

Record high temperatures were set at the following locations on April 4th:

Harrisburg set a record high temperature of 83 degrees, breaking the old record of 82 degrees set in 1999. A continuous weather record has been kept in Harrisburg since 1888.

Bradford set a record high temperature of 77 degrees, breaking the previous record of 72 degrees set in 1981.

Altoona tied a record high of 80 degrees, where the previous record was set in 1950.

CTP WATCHES/WARNINGS/ADVISORIES

None.