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Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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062 FXUS61 KCTP 162324 AFDCTP Area Forecast Discussion National Weather Service State College PA 724 PM EDT Tue Jul 16 2024 .SYNOPSIS... The heat will peak today across the region as unseasonably warm air is directed into the state on SW winds. Another round of thunderstorms with gusty, to locally damaging wind gusts and hail will move through the Commonwealth this 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 10 PM THIS EVENING/... Convection currently struggling to break the cap. High shear in the nrn tier still warrants keeping an eye on things there for another 1-2hrs, though. The shear may be too much and the heat not enough in the N for storms to hold together long enough to make good up/downdrafts. EHI is high right along the border, but only for another 1-2hrs, also. Temps has dipped (tempo) to 74F at BFD after they got a brief shower and those thicker clouds. The cu are even more shallow to the S. Expect the congestion in the clouds assocd with some convergence near the sfc from JST- AOO-MDT to pop a few cells shortly. CAPE is climbing as heat is almost to it`s peak. Heat index values are over 100 in many places SE of UNV, and right at 105 in the urban areas. These cells may grow tall enough to get some stronger up/downdrafts (DCAPE >1000J there). The forcing stretched to the S of the line of convection over BGM`s area is starting to light up, so they could also see some tall storms in the next few hrs. && .SHORT TERM /10 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... All this convection should wane as the sun sets or even before, lasting longest in the S along the Turnpike/MD border. Lack of clouds tonight could again make some valley fog, but lack of rainfall today will be a tick in the negative column. Showers may impinge on the wrn highlands by sunrise. 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, the pre-frontal heating of the a very moist/unstable airmass, combined with a belt of relatively strong mid level flow, will support a threat of severe weather Wed PM across the southeastern counties. Cloud cover and convection should hold temps down a bit Wednesday, even across the Lower Susq Valley. The Heat Advy currently up for that area for Wed will be allowed to continue as surging dewpoints ahead of the front could still yield heat indices near 100F across the southeast counties. PWs of nearly 2" in the SE could help feed very heavy downpours. But, the fast storm motions and very high FFG (widespread 4.5"/3 hrs values) keep the threat for flash flooding low. The MRGL risk in the Day2 ERO was collaborated with WPC, mainly in order to keep continuity with previous forecasts. Wed PM looks like the cfropa occurs for all but perhaps a few towns on the MD border. Thus, the SHRA should press mainly or entirely to the S of the border well before sunrise. Dropping dewpoints may keep the threat of fog low, but the temps drop right along with them. Have not added it into the wx grids at this point. && .LONG TERM /WEDNESDAY THROUGH TUESDAY/... Deterministic guidance converges towards a return towards fair and seasonable weather with lower humidity during the day Thursday 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 /23Z TUESDAY THROUGH SUNDAY/... Weakening of the mid level winds and time of day has resulted in the reduction of gusty winds since mid afternoon. This has allowed storms to reform again across the far southeast part of the area. This will use a TEMPO group across the far southeast for a few hours. Otherwise expect dry weather overnight. Earlier shifts have more showers in for early Wednesday, along with some lower CIGS and fog. Not sure this will occur, given how much the wind dried out the ground today, but with the front still to the northwest, have some showers in with lower conditions for a few hours on Wed. For later in the week, looking at much cooler and drier air. Thus should see mainly VFR conditions after Wed. Outlook... Thu...AM Showers exit southeast; MVFR cigs psbl west bcmg VFR. Fri-Sun...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 until 8 PM EDT Wednesday for PAZ036-056-057-059- 063>066. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Fitzgerald/Tyburski AVIATION...Martin CLIMATE...Steinbugl