Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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743 FXUS61 KCTP 010317 AFDCTP Area Forecast Discussion National Weather Service State College PA 1117 PM EDT Sun Jun 30 2024 .SYNOPSIS... A large high pressure system will build into the region tonight and Monday, followed by a dying cold front pushing in from the Great Lakes and stalling out over the area by the middle of next week. && .NEAR TERM /UNTIL 8 AM MONDAY MORNING/... Much drier air advecting into the region this evening with mainly clear skies noted over the Bulk of Scent PA and the Susq Valley at 0130Z. Cooler air and steep llvl lapse rates advecting SE beneath a moderately strong subsidence inversion based at 4-5 kft agl was producing fairly widespread high end MVFR and low end VFR ovc cigs across the NW 1/3 of the state attm and this cloud deck will continue to advance just a bit more overnight, but greatly break up to sct-bkn VFR (>3000 FT agl) across the Central Ridge and Valley region. aside from some patchy drizzle or some brief very light showers from the 2-3 kft thick strato cu layer across the Northern Mtns overnight, POPs over the Central Ridge and Valley Region and SE PA (where skies will be mainly clear) will be essentially zero. Low temps will vary from the upper 40s throughout the perennial cold rural valleys of the NW Mtns and Somerset Cty, to around 60 in the SE Metro Areas. && .SHORT TERM /8 AM MONDAY MORNING THROUGH 6 PM MONDAY/... High pressure builds in over the next 30 hrs. Mon should be sunny after the clouds in the NW dissipate (for the most part). Wind continues to veer to the N and the dewpoints should drop even more in the deepest mixing of the day. Td in the m40s should be common in the wrn half of the CWA in the aftn. Monday night should be foggy in the nrn and central valleys despite the dewpoints in the 40s as the air temp should get a bit lower than the river/creek water temps. Otherwise, light/no wind under the center of the 1025 high pressure area will help temps down into the m40s to l50s. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... Canadian high pressure builds to southern Ontario by Monday night, bringing a fair and cool night with the high moving directly overhead. This will result in efficient radiational cooling and min temps several degrees below normal. Fair and warmer weather is expected Tuesday into at least the first half of Wednesday, as upper level ridging builds over the state and surface high drifts offshore. All medium range guidance tracks a weakening shortwave well north of PA late Wednesday into Thursday. The dying cold front is likely to sag into the state Thursday and stall out in the vicinity of PA through Friday. Falling heights/surging low level moisture ahead of the front could support scattered convection as early as Wednesday afternoon over the northwest half of PA. However, a better chance of showers/tsra areawide will come with the arrival of the front Thu into Friday. Early best guess of late week rainfall based on ensemble plumes ranges from 0.25 to 0.75 inches, with the highest amounts over the N Mtns and least in the south. Heat and humidity should peak ahead of the front Wed-Thu. Ensemble mean 850mb temps surging to near 20C indicate max temps could reach the low to perhaps mid 90s in the Lower Susq Valley Thursday, with high humidity pushing heat indices into the mid and upper 90s. Ensemble plumes suggest slightly cooler daytime temps late week, due to more clouds/showers. However, high pwats in the vicinity of the stalling front should result in muggy nights and above normal min temps the entire second half of next week. Models begin to diverge as we head into the weekend. Most guidance suggests that rain chances stick around through at least Saturday as another cold front approaches the area. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... High pressure building in from the Grt Lks will bring VFR and breezy conditions to most of Central PA tonight. However, residual low level moisture ascending the Alleghenies will result in predominantly MVFR cigs from KBFD southward through KJST, with tempo IFR cigs in vicinity of KBFD through around 06Z. A downsloping flow should keep conditions VFR east of the Alleghenies tonight. Mixing of much drier air aloft should cause any early stratocu to dissipate by late Monday morning, with widespread VFR conditions expected the rest of the day. A fairly tight pressure gradient should result in gusty north winds for much of the day. Bufkit soundings support gusts in the 20-25kt range for most of the region. Expect winds to diminish toward evening, as the center of the high pressure system pushes into PA. 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. && .CLIMATE... At the Altoona Airport, a daily record rainfall of 0.77 inches was set on Sat, Jun 29. This total breaks the old record of 0.53 inches set back in 1972. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/DeVoir NEAR TERM...Lambert/Dangelo SHORT TERM...Dangelo LONG TERM...DeVoir/Bauco AVIATION...Fitzgerald CLIMATE...Evans/Steinbugl