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Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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356 FXUS61 KCTP 160654 AFDCTP Area Forecast Discussion National Weather Service State College PA 254 AM EDT Tue Jul 16 2024 .SYNOPSIS... The heat will continue as unseasonably warm air is directed into the state on SW winds. More storms with gusty winds and hail will move through Tues afternoon and evening. A cold front will push through on Wednesday with another round of strong to severe thunderstorms. High pressure will build in from the Great Lakes and control things for the rest of the week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Convection linked to MCV over upstate NY has exited the northeast part of the forecast area late this evening. Surface high pressure building into the area should result in fair weather overnight, with patchy late night valley fog forming where rain fell over the northern part of the state. Can`t rule out a shower/tsra toward dawn over the northwest corner of the forecast area associated with next shortwave rotating through the Grt Lks. Min temps are expected to range from the mid 60s over the N Mtns, to the low and mid 70s across the southern half of the state, where pwats are highest. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... Large Bermuda High and associated southwest flow will yield another hot and humid day across the region Tuesday. Max temps could potentially be even a bit higher than today, based on progged ensemble mean 850mb temps. However, an approaching shortwave should produce afternoon convection over at least the northern part of the state, which could temper the heat by afternoon. Diurnal heating, combined with surging pwats ahead of the approaching shortwave, should yield developing tsra during the afternoon with the highest POPs across the central and northern part of the state per latest guidance. The strongest mid level flow and deep layer shear is progged over the northern part of the state and the best combination of late day instability/shear is targeted over the northeast part of the forecast area, where HREF UHEL values are highest, signifying the best potential storm organization. Line segments producing severe/damaging gusts will be the main risk into early evening. Convection should wane with loss of heating Tuesday night, but the region will remain in a ribbon of anomalous pwats/instability and prone to at least a slight chance of lingering showers/tsra overnight. An upper level trough approaching from the Grt Lks will push a cold front through the region Wednesday, accompanied by a round of showers/tsra Wed afternoon into Wed evening. Cloud cover and an early arrival of the fropa should keep the threat of severe weather low over the northwest part of the forecast area. However, pre-frontal heating of the a very moist/unstable airmass, combined with a belt of relatively strong mid level flow, support a possible threat of severe weather Wed PM across the eastern counties. Cloud cover and convection should hold temps down a bit Wednesday, even across the Lower Susq Valley. However, surging dewpoints ahead of the front could still yield heat indices near 100F across the southeast counties. && .LONG TERM /FRIDAY THROUGH MONDAY/... Deterministic guidance converges towards a return towards fair and seasonable weather with lower humidity Friday as high pressure builds from the Great Lakes. The bulk of guidance keeps dry conditions through Saturday morning so have capped PoPs below SChc (< 15%) through this timeframe. A stalled front is expected to nudge northward into the weekend, allowing for a return to diurnally driven convection. Have capped PoPs mainly to a SChc north of the turnpike Saturday afternoon/evening with the northward extent of SChc creeping into portions of the Middle Susquehanna Valley Sunday evening where the front could continue to drift slightly north. Model guidance does outline mainly dry conditions for the majority of the day on Monday; however, diurnally driven convection cannot be ruled out in the afternoon/evening hours with the best chances mainly south of I-80. Have capped PoPs at low-end Chc (20-30%) given some uncertainty wrt boundary placement and how this will impact any potential convection. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... 16/06Z: GOES IR satellite shows valley fog in the vicinity of KBFD and KIPT - but so far minimal to no restrictions observed at the terminal. These two sites have the highest probability for IFR through 10-12Z with VFR prevailing for the most part elsewhere (patchy 5-6SM visby BR/HZ possible around sunrise). Showers and t-storms are expected across the airspace from mid morning through the evening - a few strong/severe storms are possible with local wind gusts 45-55kt from ~270 degrees. Sub- VFR cigs are most likely (>70%) at KBFD 06-12Z Wed with better than 50/50 odds at KJST. Outlook... Wed...AM low clouds west. Another round of t-storms with CFROPA especially central and southeast airfields. Thu...AM Showers exit southeast; MVFR cigs psbl west bcmg VFR. Fri-Sat...AM valley fog. Otherwise, no sig wx/VFR. && .CLIMATE... Daily record max temp of 99F was tied at Harrisburg on 7/15. Previous record was set in 1995. && .CTP WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM EDT this evening for PAZ019-025>028- 034-035-045-046-049>053-058. Excessive Heat Warning until 8 PM EDT this evening for PAZ036- 056-057-059-063>066. Heat Advisory from 8 PM this evening to 8 PM EDT Wednesday for PAZ036-056-057-059-063>066. && $$ SYNOPSIS...Lambert/Dangelo NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald/Dangelo LONG TERM...Fitzgerald/NPB AVIATION...Steinbugl CLIMATE...Steinbugl