textproduct: State College

WHAT HAS CHANGED

* Extended a brief period of likely POPs for showers early today across Southern PA and the Lower Susq Valley

KEY MESSAGES

1) Upper level low pressure near Toronto Ontario early today will drift northeast and diminish its influence on our cool temps and occasionally showery conditions through the midweek period with a gradual warmup in temperatures Tuesday through Thursday.

DISCUSSION

KEY MESSAGE 1: Upper level low pressure near Toronto Ontario early today will drift northeast and diminish its influence on our cool temps and occasionally showery conditions through the midweek period with a gradual warmup in temperatures Tuesday through Thursday.

Left exit region of an upper level jetlet rounding the base of the upper trough combined with a CFA and sfc reflection in the form of a weak trough has led to areas of showers advecting into South-Central PA and the Lower and Mid Susq Valley early today (and even a few low- topped TSRA a few hours ago near and to the North of KIPT).

Expect a fair amount of morning sunshine across the bulk of Central PA after this current, embedded shortwave trough exits to the east and NE later this morning. However, unseasonably cool temps aloft (850 temps mainly +8 to +9C today) will lead to the sunshine taking on a self destruct form with plenty of MDT CU/Thickening strato cu developing /advecting ESE from the NW Mtns twd the central ridge and valley region. The next compact shortwave and mid/upper level speed max will rotate through a bit further to the north today, focusing the vast majority of any showers near and to the north of the RT 6 corridor in northern PA.

As noted in previous discussions and based on current high res ensembles and its members, it's unlikely that any precip will get south of I-80, but there will be plenty of clouds. Some showers will linger into the night and possibly early Tuesday before drier air works in as the upper trough departs.

Vertical mixing depth increasing to 4-6 kft after 14Z today will lead to a quick increase in the West to West-Southwest breeze with moderate gusts into the upper teens at times. There will be nearly a 20 deg delta in max temps from North to South today, with reading struggling to reach 60F across the highest terrain near and north of RT 6, while the Lower Susq Valley sees afternoon highs in the mid to upper 70s. These high temps will be 10-13F below normal across the Northern Tier counties and just a few degrees below normal in the Lower Susq Valley.

AVIATION /07Z MONDAY THROUGH FRIDAY/

Upper level trough swinging across the area along with a west to southwest flow over the Great Lakes will continue to bring clouds and periods of rain, mainly across the SE airfields early this morning and the NW Mtns during the daylight hours today. This weather pattern is more typical of late September than late August.

Post rain restrictions appear most likely at BFD and JST in the form of low ceilings and/or areas of morning radiational fog.

IFR/LIFR ceilings are possible through 12Z with confidence highest at BFD (80-100%). VFR elsewhere.

After daybreak, isolated showers and possibly a thundershower remain in the forecast across the northern tier. Cumulus and stratocu will build through the day, but bases will generally rise to VFR levels in the afternoon. MVFR cigs are expected to linger longest at BFD.

Outlook...

Tue...MVFR cigs possible in the AM across the NW, then trending VFR. Showers/thunderstorms possible in northern tier.

Wed...Patchy morning fog, otherwise mainly VFR conditions.

Thu-Fri...Chance of showers and storms again, mainly Thursday PM.

CTP WATCHES/WARNINGS/ADVISORIES

None.