Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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150 FXUS61 KCTP 271731 AFDCTP Area Forecast Discussion National Weather Service State College PA 131 PM EDT Thu Jun 27 2024 .SYNOPSIS... *Seasonable end to the week with comfortable humidity *Return of heat+humidity fuels T-storms this weekend *Cooler & dry start to July; heat & T-storms by the 4th && .NEAR TERM /THROUGH TONIGHT/... Cu will crumble this evening setting up a refreshingly cool and mainly clear night across central PA. Low pwats and favorable radiational cooling pattern supports trending below the 50th percentile NBM with relatively chilly min temps in the mid 40s across the northern tier. Beneath dome of 1020mb high pressure, synoptic conditions support fog formation late tonight into early Friday morning in the river/stream valleys across the western and northern Alleghenies. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AM fog will dissipate quickly after sunrise Friday. Expect partly cloudy and seasonably comfortable conditions with highs 75-85F. An increasingly strong southerly llvl return flow develops into Friday night as the aforementioned surface high shifts eastward off the New England coast. Latest model data suggests 30-40kt LLJ from the south-southwest will drive some showers and elevated t-storms over west central PA late Friday night into early Saturday morning. The belt of strong 850mb flow will transport rich low level moisture (dewpoints in the upper 60s to lower 70s) northeastward along/ahead of a cold front this weekend. PWAT values are forecast to reach 1.5-2.5 inches on Saturday or +2-3SD. The anomalous deep layer moisture will support risk of heavy to potentially excessive rainfall. WPC currently has a broad MRGL risk, but the setup will likely yield an upgrade to SLGT risk particularly where FFGs are reduced. Although mid lvl lapse rates may remain weak, high dewpoints and diurnal heating should fuel at least moderate buoyancy by mid/late afternoon. The projected instability and deep shear profiles support a conditional risk of strong to severe storms. SPC has most of the area in a MRGL risk for D3, but their discussion suggests a categorical upgrade/expansion of SLGT risk (just to the west) is possible in subsequent outlooks. The influence of early day clouds/waning overnight convection could be a limiting factor. Convection should decrease in coverage and intensity into Saturday night, which will be warm and muggy with lows 65-75. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Latest model consensus shifts primary t-storm/svr wx risk to the southeast on Sunday with max POPs across the far southeastern portion of the forecast area. Highs on the last day of June are fcst to reach the low 90s in the lower Susquehanna Valley with max heat index values approaching 100F in some locations. There is high confidence that July will start relatively cool and dry with near to slightly below normal temps and low humidity lasting through early next week -- thanks to another seasonably strong high pressure system. The pattern for the first week of July is almost a repeat of 6/25-6/29 with comfortable days and cool nights followed by a ramp in heat and humidity driving max temps and chance of t-storms higher by the 4th of July. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... IFR and MVFR stratus across the central mountains and Alleghenies this morning will break up into fair weather cu and eventually dissipate today. All TAF sites will be VFR by mid morning. Winds will remain from the NW with gusts generally less than 20 kts. Outlook... Fri...Generally VFR. Sat-Sun...Thunderstorm impacts possible. Mon...Generally VFR. && .CLIMATE... Through 6/26, June ranks as tied for the second warmest on record at Harrisburg. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Steinbugl AVIATION...Dangelo/Colbert CLIMATE...Steinbugl