textproduct: State College

WHAT HAS CHANGED

* Complex weather pattern with minor changes at this point.

KEY MESSAGES

1) Turning warmer Tuesday and lasting into early Wednesday.

2) Low pressure tracking just to the north and west of the area to bring some light snow to much of the area late Wednesday into early Thursday.

3) More cold and wind for Thursday. Complex storm. The potential remains for low pressure to develop along a nearly stationary frontal boundary over the Mid- Atlantic region coast and perhaps impact Pennsylvania during the second half of the week, with snow or a wintry mix. There is still a significant range of outcomes, including that only a weak storm will storm will form with lighter precipitation. Stay tuned for later forecasts.

DISCUSSION

KEY MESSAGE 1...

High pressure to our south and low pressure tracking to our north will result in a southwest flow of milder air Tuesday into Wednesday.

Temperatures will trend above normal into early Wednesday, with mainly dry conditions. Breezy conditions will prevail.

A bit of light snow could brush the northern tier of PA by early Wednesday, but little if any accumulation is expected.

KEY MESSAGE 2...

Low pressure tracking northwest of the area on Wednesday will bring some light precipitation to central PA. Most of the precipitation would be west of our area prior to 18Z Wed.

Some light snow will be across the north and west later in the day on Wednesday as a series of cold fronts move across the area. A northwest flow of colder air and gusty winds form behind the low, thus 1 to 2 inches of snow will be possible across the northwest and west, before the snow ends later on Thursday.

Further east across the Susquehanna Valley, rain is expected later Wednesday afternoon and early evening. Normally the precipitation ends across the southeast before the cold air can work in behind the cold front, but in this case a light dusting of snow could fall across the southeast Wednesday night and early Thursday morning.

KEY MESSAGE 3...

Thursday will feature the potential for lake effect snow, upslope snow, and gusty winds again. SFC ridging expected for Friday, but some model spread to the details on how the coastal forms. For now Friday looks to be mainly dry.

Also a complex system for the upcoming weekend. Overall pattern favors a fast jet stream with shots of abnormally cold air every several days, vs. a large storm. The jet stream has been strong lately, given the abnormally warm air across the southern plains and the strong upper level low over eastern Canada. Been largely in this pattern since November.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Persistent patch of low clouds are currently being observed across northern Pennsylvania; however, moderate confidence MVFR ceilings scatter out at BFD between 00Z-01Z Tue based on current satellite trends and recent GLAMP model guidance trending towards VFR conditions closer to 00Z Tue. Widespread VFR conditions expected elsewhere with very high (~80-90%) confidence. Main concern through 00Z Wednesday will be the presence of LLWS at BFD in the near-term with LLWS thresholds very close to being met, with recent NBM model guidance indicating this threat through ~04Z Tue. LLWS concerns return to the western highlands later in the 00Z TAF period, generally after 18Z Tue, with moderate (50-60%) confidence in magnitude of LLWS and more uncertainty with respect to timing. Low-to-mid level clouds increase towards the end of the 00Z TAF package with high (~70-80%) confidence with further deterioration progged by a combination of NBM/HREF guidance after 00Z Wed.

Outlook...

Wed...Light rain/snow gradually overspreading the area, with deteriorating cigs and vsbys.

Thu...Restrictions persisting across N/W PA in occasional -SHSN; windy.

Fri...Marginal improvement, not as windy.

Fri Night-Sat...Light snow and restrictions possible across primarily western PA.

CTP WATCHES/WARNINGS/ADVISORIES

None.