Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 190633 AFDCTP Area Forecast Discussion National Weather Service State College PA 233 AM EDT Mon Aug 19 2019 .SYNOPSIS... It will remain very warm and humid into early this coming week and a meandering trough of low pressure will keep the mention of mainly afternoon and evening showers and thunderstorms in the forecast. Cooler and much less humid air will arrive for Thursday through Saturday with dry conditions expected. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Scattered, pulse-type convection rapidly diminishing in coverage and intensity late this evening, as boundary cools. Expect this trend to continue through around 06Z, then will reintroduce the chance of late night showers and possible tsra over the northwest counties in association with a weakening cold front approaching from the Grt Lks. It will be another muggy overnight with lows ranging from the mid 60s over the north to around 70F SE. A light southerly breeze should preclude widespread fog, but still expect patchy fog where there was rain today, especially over the southeast half of the state, where the pressure gradient is weakest. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... Dying cold front will slowly cross the state Monday. Any morning showers along the front should be isolated and confined to the northwest counties. However, diurnal heating of moist, pre- frontal airmass will cause convection to become more widespread by afternoon. Model soundings indicate deep layer shear will be weak, so organized severe weather appears unlikely. However, model CAPEs support the potential of isolated damaging wind gusts/large hail, mainly along and east of the Susq River. A hot and humid day is on tap with heat indices peaking near 100F across the Lower Susq Valley. Model soundings indicate max temps will be similar to Sunday, with highs ranging from the low 80s along the NY border to the lower 90s in the valleys of southern PA. The combination of heat and humidity may warrant the issuance of a Heat Advisory for a few hours Monday afternoon. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Made some very small changes to this part of the package, given not a lot of change on guidance and storms on the radar. A trend toward cooler and drier weather is expected for the later part of the week, as a cold front moves east of the area. Perhaps a shower toward the later part of the weekend. More detail below. Guidance continues to show a fairly vigorous upper trough crossing the northeast quadrant of the lower 48 this period. Within the upper trough, there are still smaller scale detail differences that will affect progression/speed of the leading surface cold front and will take more time to be resolved. The cold front will be a focus for convection as it pushes southeast Wed-Thu. While predictability is too low and limited at this range, severe storm risk upgrades are possible into the short term. Late-summer heat episode continues into midweek with max temperature anomalies +5-10F above normal on Wednesday. At this time, expect Thursday to be the transition day with a relative cooling trend and push of drier air throttling temps back to near/slightly below avg. Friday into the weekend. Lower humidity will spell pleasant days and comfortably cool nights. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... Line of t-storms over far wrn PA (KJHW-KHLG) at 0630Z should continue to weaken as they enter the western part of the airspace between 07-08Z. High confidence in low ceiling below alternate mins at KIPT (given obs trend) until 13Z. Leaned toward persistence forecast for the rest of the central and eastern TAFs with limited impacts mainly at KLNS. VFR expected to prevail by mid morning and through the afternoon. Convective corridor appears to be focused over the eastern airfields this afternoon-evening and therefore only went with VCTS at KIPT, KMDT and KLNS. Any clearing tonight would favor fog formation especially where it rains. .Outlook... Tue-Wed...Rounds of PM showers/thunderstorms. Late night and early morning fog/low clouds. Thu...Trending VFR northwest; chance of t-storms southeast. FROPA Thursday night. Fri...No Sig Wx. && .CLIMATE... Record max temperatures for August 19: Harrisburg 97 in 1966 Williamsport 94 in 1899 Altoona 91 in 1983 Bradford 86 in 1978 State College 96 in 1899 && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald/La Corte LONG TERM...Martin/Steinbugl AVIATION...Steinbugl CLIMATE...Steinbugl is the U.S. government's official web portal to all federal, state and local government web resources and services.