textproduct: State College

WHAT HAS CHANGED

Wind Advisory no longer in effect for Cambria & Somerset Counties

KEY MESSAGES

1) Periods of rain continue into tonight associated with the remnants of Isaias

2) Big temperature swing forecast for the week ahead

DISCUSSION

KEY MESSAGE 1: Periods of rain continue into tonight associated with the remnants of Isaias

Steady light to moderate rain (rates generally <0.50 in/hr) will be most persistent along and east of the Allegheny Front this evening into tonight. Increasing MUCAPE and elevated instability could result in some locally heavy, short duration rain/rates across south central PA into tonight. Much of this area has already picked up 1-2" since Saturday evening, so we still can't rule out some isolated runoff problems. Otherwise, the prolonged dry run leading up to this Isaias rain event has allowed a sufficient cushion for what has largely been a duration type heavy rain episode with some locations ticking over 3 inches in the past 24 hours. Current MA/OH RFC river guidance keeps all fcst points below action stages, thanks to very low flows at the start of the event.

KEY MESSAGE 2: Big temperature swing forecast for the week ahead

Noticeably warmer and more humid conditions expected early this week with max temps on Tuesday forecast to peak 10-15 degrees above the historical average for mid October and possibly challenge daily records with highs in the 70-80F range.

Improving weather conditions can be expected Monday as the remnants of Isaias exit the Mid Atlantic. Rain chances on Tuesday appear to be maximized over the northern tier where a shortwave aloft and sfc cold front (infused with moisture from TS Rachel?) streak eastward from the Great Lakes. SPC has highlighted this area with a conditional low risk level 1/5 for severe t-storms. Another period of rain is likely late in the week, but exact timing remains uncertain.

Confidence is increasing in a seasonably chilly cooldown and big temperature swing (vs. early in the week) for the upcoming weekend. The substantial cooldown appears to be delivered in the wake of a strong cold front by gusty west-northwest flow directing the colder air over the Great Lakes. This could setup some lake effect/upslope rain or snow showers (yes, first flakes possible in the Alleghenies/Laurel Highlands) followed by frost and freeze conditions. To quantify the magnitude of the fcst temp swing this week, Bradford could go from 75 degrees Tuesday afternoon to 25 degrees by early Sunday morning (50 degree swing!)

AVIATION /18Z SUNDAY THROUGH FRIDAY/

MVFR to IFR restrictions prevail across central Pennsylvania this afternoon as the remnants of Isaias bring low ceilings, reduced visibilities, and periods of rain. Areas of steady rain this afternoon will taper off to spotty showers and drizzle this evening across much of the Commonwealth; an exception to this will be over portions of southern Pennsylvania which are closer to the low pressure center (KMDT/KLNS), where additional showers and perhaps even a few thunderstorms may develop (MUCAPE of around 500 J/kg).

For the overnight period, IFR to LIFR restrictions are favored across the Northern Tier and Alleghenies (KBFD/KJST), with primarily IFR elsewhere across our area. With that said, northerly flow on the flank of this system as it begins to depart may filter in enough dry air to result in SCT-BKN IFR decks, primarily east of KBFD/KJST. However, prevailing IFR was maintained given low confidence in sustained improvements during the night following today's rainfall.

By Monday morning, showers are expected to have cleared our area. Sky conditions will gradually trend toward MVFR through the early afternoon, and perhaps even VFR later in the afternoon (mainly for KIPT/KMDT/KLNS).

Outlook...

Tue...VFR favored, though a front approaching from the north may bring restrictions in -SHRA. AM fog possible.

Wed...Restrictions from low ceilings and -SHRA possible as the front moves southward across the Commonwealth.

Thu...A period of VFR is favored behind the front, with a chance for restrictions and -RA later on Thursday as the front oscillates back northward.

CLIMATE

Daily record high temperatures for October 13th: MDT 85/1954 IPT 83/1954 AOO 82/2024 BFD 78/1969 STC 82/1930

CTP WATCHES/WARNINGS/ADVISORIES

None.