Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 291129 AFDCTP Area Forecast Discussion National Weather Service State College PA 729 AM EDT Fri Mar 29 2024 .SYNOPSIS... High pressure will briefly build into Pennsylvania today into tonight, then a weak area of low pressure approaching from the midwest will pass across the state Saturday. A more significant low is likely to track eastward across Pennsylvania early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Large scale subsidence and low-pwat air behind the exiting east coast trough will result in mainly sunny, breezy and seasonable weather later today. Mixing down model 850mb temps of around -1C to -4C translates to expected highs ranging from the mid 40s over the N Mtns, to the mid 50s across the Lower Susq Valley. Bufkit soundings also support wgusts several knots above NBM guidance this afternoon and dewpoints a few degrees below, due to fairly deep mixing. Higher fuel moistures should limit the risk of wildfire spread, despite expected wind gusts of 25-30kts and RH falling to around 30pct. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... Surface ridging should build into the state tonight, resulting in fair weather and diminishing winds. Focus then shifts to a weak area of low pressure lifting out of the midwest states. This feature is progged to track across the Lower Grt Lks Saturday, with the attendant warm front spreading rain into Central PA. Latest ensemble plumes indicate rain should fall primarily during the afternoon hours, with likely totals by evening ranging from around 0.33 inches over the NW Mtns, to around 0.10 inches over the Lower Susq Valley. It`s hard to see temps rebounding as much as the NBM depicts Saturday across the NW counties, given thickening clouds and arriving rain ahead of the advancing warm front. Have therefore blended in the much cooler GFS/NAM surface temps. Model consensus tracks the surface low along the southern tier of NY state Sat night, with a trailing cold front sweeping south of PA by dawn. The bulk of the rain should have ended by 00Z Sunday, as the mid level shortwave and bulk of the large scale forcing will have shifted east of the area by then. However, a bit of drizzle could accompany the advancing warm front in the evening and a few lingering showers are possible with the cold front passage overnight. A mild and dry day is expected to round out the weekend on Sunday with ridging nosing in from the Grt Lks. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Sunday looks dry to start as a west-to-east oriented boundary sags south of the Mason-Dixon Line. A wave of low pressure along that boundary will lift back into Pennsylvania early next week, bringing widespread rainfall Sunday night through Tuesday. Zonal flow aloft often promotes seasonable temperatures, but rain and clouds will likely result in temperatures trending a bit below average for the start of April with highs in the upper 40s to low 50s. For the second half of the week, ensemble guidance depicts a deepening low pressure system moving into the northeast and bombing out off the New England coast. This system is likely to bring ample precipitation and strong winds. Current temperature profiles indicate some snow potential at higher elevations in the northern mountains and Laurels, but details remain highly uncertain. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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Moderate-to-high (60-70%) confidence in VFR conds prevailing across central PA through 12Z Saturday. The main uncertainty with regards to the forecast will be the lower clouds across SW PA for the next couple of hours. Coverage is the main point of uncertainty, with borderline MVFR/VFR cigs that could drop JST/AOO to MVFR thresholds if thickening of the cloud deck occurs. The bulk of near-term guidance does outline a low cloud deck dipping southward from NY in the late morning to early afternoon hours. Elsewhere, SKC/SCT high- level clouds are expected to prevail for a majority of the forecast area. The main concern in the next 24 hours aviation-wise will be with respect to gusty winds (sustained 15-20 kts with gusts up to 30 kts) at 290-330 after through the evening hours. Some concern for LLWS criteria being met after 03Z Saturday through the end of the forecast period at airfields along the southern ridges due to a localized enhancement of the LLJ. The 12Z TAF package outlines this potential for AOO/JST/UNV which outline higher (60-70%) confidence for these thresholds being met, while keeping mentions out of MDT/LNS due to relatively lower (30-40%) confidence at this time. Outlook... Sat...Rain moves in from W early AM, restrictions possible. Sun...Lingering rain across mainly SW PA early, rain moves in and becomes areawide later in the day. Mon-Tue...Widespread rain continues with some potential for TSRA Tuesday afternoon into the evening.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Banghoff AVIATION...NPB

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