Area Forecast Discussion
Issued by NWS State College, PA

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022 FXUS61 KCTP 240548 AFDCTP Area Forecast Discussion National Weather Service State College PA 148 AM EDT TUE MAY 24 2016 .SYNOPSIS... Upper level low pressure centered over Long Island today will move off to the northeast on Wednesday. A noticeably warmer and more summer-like pattern with isolated showers each afternoon and evening is expected to last into the first part of the holiday weekend. slightly cooler weather may arrive for Memorial Day. && .NEAR TERM /THROUGH TODAY/... Upper low will slide up to Boston harbor today. The cooler air aloft will still result in some instability showers this afternoon. LI`s barely go negative - probably because all the instability will be below 10kft. A cap about that high or even lower should keep things suppressed. But, a few shra could pop over the ridges - mainly in the SE third of the area - and drift SSE. will hold POPs to 20s east of the Main Stem Susquehanna River. Otherwise, the ridging starting to translate eastward will keep the cu down over western PA. Maxes should get back to where they were today and maybe add two degrees due to less clouds and very slightly warmer 8H temps. && .SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/... After any diurnal convection dwindles at or before sunset, the rest of the night should be quiet. Some patchy fog is possible but dewpoints fairly low/dry. Sinking motion is maximized on Wednesday as the upper ridge is nearly overhead. It should be a good day to make some vitamin D. We should add another 2-4F onto the maxes from Tuesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Extended guidance continues the idea the development of an eastern ridge/western trough pattern, bringing the arrival of the first extended period of summer-like temperatures and humidity. By Thursday we will be embedded in a broad wsw flow aloft. Slightly above normal PWATS support the idea that humidity will become noticeable over most of the area for the first time this warm season. It also means we will be susceptible to mainly afternoon convection pretty much on a daily basis into the weekend. The limiting factor will be the eventual sharpness of the upper ridge and how warm we manage to get aloft. The GFS is very aggressive poking the Bermuda ridge strongly up over the eastern U.S. Saturday while the ECMWF is a little flatter. The NAEFS is more in line with the GFS which hints that Saturday could be the day with smallest convective chances. I don`t have anything more than chance pops in the extended given the muddy nature of the ridge and low confidence that it will be able to shield us from upstream convection that will be embedded in the flow. The highest confidence part of the forecast is for temperatures to be above normal through the end of the month. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... Regional radar mosaic at 00Z shows the last of the diurnally-driven showers falling apart over southern Pa. For much of central Pa, confidence in vfr conds overnight is high. However, fog is a concern across portions of southern Pa, esp where rain fell earlier today. The dwpt depression at KMDT is only 6 degrees at 23Z, and with clearing skies developing toward sunset it`s an ideal setup for fog. Current hrrr and lamp guidance not indicating any vis restrictions there this evening and only mvfr restrictions late tonight, but felt compelled to paint a more pessimistic picture in the TAF. Current dwpt depressions and SREF probs suggest KLNS may also experience some fog late tonight. Elsewhere, the prospects of sig vis reductions appear low overnight. Ridge of high pressure will build in from the west on Tuesday, bringing a near certainty of widespread VFR conds. OUTLOOK... Wed...No sig wx expected. Thu-Sat...Isold pm tsra impacts possible. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...RXR AVIATION...Fitzgerald

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