textproduct: State College

WHAT HAS CHANGED

* Nudging temps cooler than NBM mean Fri night-Sunday morning.

KEY MESSAGES

1) Much drier air is moving in, and will result in a couple of fair and dry days.

2) Upper low over eastern Canada will spin a compact closed low through the northeast Friday-Saturday. Colder air and a dry spell will follow.

DISCUSSION

KEY MESSAGE 1: Much drier air is moving in, and will result in a fair and rain-free day.

Dewpoints are dropping with 40s already into about half the CWA as of 2 AM EDT. A patch of mid clouds with radar returns under it may try to make a sprinkle over the Laurels before sunrise. But, the dry air under it will likely keep it just a sprinkle if it makes it to the ground. Fog is evident on the fog enhancement sat images over srn Somerset Co where the heaviest rain fell yesterday. But, the dry air (Td in the L50s there) already seems to be killing it off and pushing it south of the MD border.Will monitor for any redevelopment, or even a little in the river valleys of the north as temps dip. But, no hints of fog up there just yet.

The high pressure area moving in from central Canada will keep things dry. However, some cu will form over the NErn two-thirds of the CWA today as slightly cooler air aloft moves overhead. Wouldn't be surprised to see some drops try to fall out of the clouds, but they will evaporate before hitting the ground.

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KEY MESSAGE 2: Upper low over eastern Canada will spin a compact closed low through the northeast Friday-Saturday. Colder air and a dry spell will follow.

High pressure aloft and at the sfc will set up just to our west, and deflect a compact upper low off to our east, but not by much. The cold front associated with the upper feature will arrive late Friday. Other than kicking up the wind a little late Fri-Fri night, it should not generate measurable precip in the CWA due to the minimal moisture held by the system. The more- notable change will be the reduction in temps on Saturday as 8H temps dip close to 0C in the NE and low single digits elsewhere. NBM does not seem to reflect this possibility, so we went with a blend of MOS guidance and NBM for maxes. Sat night could get pretty chilly as the wind dies down overnight. Some places in the nrn tier could go below 40F, with all the CWA hitting the 40-45F range for mins. Temps should rebound into the 70s Sunday.

The chance of precip inches up into the 20-30pct range for the first half of the new week starting with another shot of lowered heights/pressure aloft around Monday. But, there really aren't any strong signals for a widespread rainfall for days 4-8 as the upper ridge to our west holds firm and makes it tough for Gulf and Pacific moisture to get into PA.

AVIATION /12Z THURSDAY THROUGH MONDAY/

VFR conditions are expected through the TAF period with mainly dry conditions. Northwest winds will increase through the morning to 10 to 15 knots with gusts of 20 to 25 knots likely. Gusts could approach 30 knots during the afternoon at MDT and LNS. Cool air aloft combined with diurnal heating will allow for scattered to broken clouds to develop between 5000 and 8000 feet with some spotty light showers. Skies quickly clear out after sunset and winds will decrease to less than 5 knots.

Outlook...

Thu-Mon...VFR with no significant weather expected.

CTP WATCHES/WARNINGS/ADVISORIES

None.