Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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023 FXUS61 KCTP 020319 AFDCTP Area Forecast Discussion National Weather Service State College PA 1119 PM EDT Mon Jul 1 2024 .SYNOPSIS... A large high pressure system will build into the region tonight and Tuesday, followed by a dying cold front pushing in from the Great Lakes and stalling out over the area by the middle of next week. Very warm and quite humid air will return for the second half of this week and last into the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Surface high pressure and associated low-pwat air mass building over PA tonight will result in efficient radiational cooling and min temps several degrees below seasonal normals. Have undercut NBM low temps by a couple of degrees, with expected daybreak readings ranging from the mid 40s in the cooler valleys of the Alleghenies, to the low 60s in the more urbanized spots of the Lower Susq Valley. Despite very dry air over the area, expect a large air/water temp difference of >25 degrees to result in patchy late night fog in the deep river/stream valleys north of I-80. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... Upper level ridging building into PA from the west will result in fair and warmer conditions Tuesday. However, the surface high and associated low-pwat air will remain parked over the state, so expect humidity to remain low. Mixing down model 850mb temps of around 13C translates to expected highs ranging from the mid and upper 70s over the higher terrain of the Alleghenies, to 80-85F in the valleys. Very dry air above a weak inversion the forecast soundings is a reliable indicator of dewpoints falling below NBM guidance, so have leaned toward the lower MAV/NBM10pct numbers. Warm advection aloft ahead of a weak shortwave cresting the top of the ridge will likely produce some thin cirrus Tuesday, but sunny to mostly sunny wording should suffice. The warmup will continue into Wednesday with an uptick in humidity as the surface high drifts off of the Mid Atlantic coast, accompanied by a return southern flow. GEFS 2m temp anomalies are a few degrees above normal over the W Mtns and near average elsewhere, translating to highs well into the 80s. Moisture advection ahead of an upstream cold front could potentially support a shower/tsra toward evening across Warren/Mckean counties. Otherwise, upper level ridging should ensure another mostly sunny, rain-free day across Central PA. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... All medium range guidance tracks a dying cold front southward into Central PA Thursday, accompanied by a good chance of showers/tsra. Latest RH profiles suggest there will be plenty of cloud cover and progged mid level flow doesn`t look overly impressive. Therefore, the severe weather threat currently looks limited. Best guess of areal average rainfall looks to be between 0.25 and 0.50 inches based on ensemble plumes. The front is progged to stall out in the vicinity of Southern PA Thursday night, then return north as a warm front Friday ahead of low pressure lifting across the Grt Lks. Falling heights and surging pwats ahead of an upstream shortwave and associated surface low lifting across the Grt Lks should bring a round of showers/tsra in the Friday PM to Saturday timeframe. Current guidance suggests the shortwave and bulk of the large scale forcing will pass north of PA, leading to unimpressive mean qpf in the ensemble plumes of 0.25 to 0.50 inches Fri PM to Saturday. The bulk of guidance now supports fair and seasonable conditions Sunday into at least early Monday, as surface riding and drier air work in behind the cold front. Temperatures in the long term forecast look above average, especially overnight lows Thursday and Friday night, when EPS pwats are 150pct of normal. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... VFR conditions and mainly clear skies will prevail tonight and Tuesday. There is a very small chance (<20%) that patchy valley fog will impact airfields in the NW mountains. No mention of fog has been made within the TAFS due to low probabilities. Winds diminish this evening as the center of high pressure builds over the region. Tuesday is expected to remain dry with fair weather and light winds to persist until Wednesday night. Outlook... Tue...Patchy AM valley fog N Mtns. Wed...Evening tsra impacts possible NW Mtns. Thu...AM low cigs possible W Mtns. Sct PM tsra impacts possible. Fri...Sct tsra impacts possible, mainly PM. Sat...Chc tsra throughout the day. && .CLIMATE... June 2024 was the warmest June on record for Bradford with a mean temperature of 66.6F, breaking the old record of 65.8F set in 2021. June 2024 was the 3rd warmest June on record for Harrisburg with a mean temperature of 76.0F. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Fitzgerald AVIATION...DeVoir/Bowen CLIMATE...Colbert