textproduct: State College

WHAT HAS CHANGED

* Increased cloud cover early today across the Central and SE zones

* increased POPs for Central and Eastern portions of the CWA late Friday/Fri night

KEY MESSAGES

1) Tranquil weather continues today through Thursday night with still below normal - but relatively milder - temperatures compared to recent weeks

2) Light accumulating snow is possible mainly Fri afternoon and Night, followed by gusty winds and another shot of Arctic air with sub zero wind chills for the upcoming weekend

3) Milder days likely for the middle and latter part of next week

DISCUSSION

KEY MESSAGE 1: Tranquil weather continues today through Thursday night with still below normal - but relatively milder - temperatures compared to recent weeks

A cold front near a KAVP to KSEg and KMRB line at 09Z this Wed will be followed by deepening dry air and clearing - with generally SCT strato cu across the bulk of the forecast area by 13Z today.

Shallow vertical mixing today will tap 10-12KT winds at a maximum in some gusts, though the bulk of the wind speeds today will be AOB 8 KTS.

Temperatures will generally top out in the 20s areawide with lows around daybreak Thursday in the single digits to lower teens.

KEY MESSAGE 2: A few periods of light accumulating snow are likely, mainly Fri afternoon and Night, followed by gusty NW winds and another blast of Arctic air with sub zero wind chills for the upcoming weekend. Model consensus suggests 1-2 inches for much of the region with a few 3 inch reports not out of the question.

Low pressure system will ride along the top of the western US ridge and race southeast across the Great Lakes late this week. This storm will have a strong ridge of high pressure behind it, ensuring a tight pressure gradient, reinforcing Arctic air, and strong winds in its wake.

As the sfc arctic front and CFA pushes across the region late Friday/Friday night, a few snow squalls appear likely, which could add another coating to 1+ inches on top of the earlier snow accums.

The bigger story will be the wind and cold to follow. Single digit (above and below zero) temperatures and below zero wind chills across much of the region are favored Saturday through Sunday morning and again later Sunday night and early Monday. Cold weather products might be needed between Saturday morning and Sunday morning, given the current winds and temps in the fcst.

Some guidance suggests another clipper system may bring light snow on Sunday, but PoPs are limited to 30 pct or less at this time.

KEY MESSAGE 3: Milder days likely for the middle and latter part of next week

As was the case on Monday, medium range ensemble guidance is still holding onto a notable several day stretch of milder temps (possibly around to several deg F above normal) for the second half of next week.

Surface high pressure moves to our east and a progressive/somewhat flat upper level ridge descends down the easter side of the Central/ NRN Rockies and warming before moving east across the Plains/Midwest/Ohio Valley, and eventually PA.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

MVFR conditions across portions of northern/western Pennsylvania will dissipate by 04/14Z with high (~80-90%) confidence based on a consensus of HREF/NBM/GLAMP model guidance as cloud cover slowly begins to shift further south/east of the area. These trends are tracking fairly well with recent ECONUS Nighttime Microphysics, hence the increased confidence with respect to airfields lifting towards VFR. Between 04/14Z and 05/00Z, all model guidance points towards widespread VFR conditions, leading towards the 04/12Z TAF package highlighting a brief period of clear skies before high clouds begin to filter into the region with a scattered deck of low- level clouds (generally above 4kft AGL).

After 05/00Z, model guidance becomes less certain with respect to ceilings across the western airfields (BFD/JST) as more recent HREF/NBM model guidance begins to indicate favorable signals for IFR conditions, especially after 05/06Z through the end of the TAF package. Recent HREF probabilities for ceilings below IFR thresholds max out at BFD between 60-80% with slightly lower, but still fairly notable, probabilities between 50-60% at JST in the 05/06Z to 05/12Z timeframe. GLAMP model guidance has been much more keen IFR/LIFR thresholds being met at BFD, thus seems extremely plausible to indicate LIFR conditions with the most uncertainty with respect to onset timing having some potential to begin as early as 05/03Z. At JST, lower confidence on LIFR thresholds being met; however, with HREF model guidance indicating similar probabilities at BFD, see no reason not to include LIFR mentions after 05/06Z, just with lower confidence.

Outlook...

Thu...Mainly VFR. MVFR cigs poss NW, mainly AM.

Fri...SN, mainly light. NW: IFR (90% chc), LIFR poss (40% chc). SE: MVFR (80% chc), IFR (40% chc).

Fri PM...CFROPA SHSN with IFR likely west & central, SNSQ also poss (30%), LIFR poss (50%). SE: -SN ending.

Sat...Sct AM SHSN/MVFR BFD/JST. No sig wx elsewhere.

Sun...VFR.

CTP WATCHES/WARNINGS/ADVISORIES

None.