Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 191344 AFDCTP Area Forecast Discussion National Weather Service State College PA 944 AM EDT Wed Oct 19 2016 .SYNOPSIS... A weak cold front over Central Pennsylvania this early today will drift southeast today...accompanied by some morning showers. Slightly air will follow the cold frontal passage...but afternoon highs today will still be well above normal...and possibly near record highs once again in the south- central and southeast part of the state. Unsettled conditions will redevelop for the end of the week as a series of low pressure areas ripple up along the trailing cold front. Brisk and much colder weather will move in for the weekend and the first snowflakes of the season are possible Saturday and Saturday night across the Northern and Western Mountains of Pennsylvania with even a light accumulation possible on some of the ridgetops across the Laurel Highlands and Northwest mountains. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A cold bisecting the state from northeast to southwest this morning will slide further south and weaken today as it reaches the souther tier counties of PA. Earlier showers that drifted across the Central Ridge and Valley Region of the state brought several hundredths of an inch across the scent counties and Middle Susq valley...and between 1 and 2 tenths of an inch invof KUNV...KPSB...KFIG and KDUJ. The showers have since dissipated a great deal to widely scattered coverage and light intensity across the Middle Susq Valley, South Central Mtns and Laurel Highlands. This will be the case for the rest of the morning...with a trend toward clouds slowly breaking in the developing downslope llvl flow over Central PA, and dry llvl advection behind the front. Min temps early today will range from the mid 50s northwest to the lower to middle 60s south...still well above normal. Morning clouds and some showers will be present across the southern half of the state. Big question today is how much cloud cover (a likely dual layer of stratocu) will linger invof of the dying cfront later this morning and this afternoon to impact potentially very warm temps across the southeast. Considering the very anomalously warm temps in place across much of the region attm (in the l60s across the NW Mtns, mid to upper 60s elsewhere) any significant breaks across the Lower Susq Valley could easily send temps just above 80F. The record for KMDT today is 82 degrees set way back in 1945, and our current fcst high for there is around 80F. The record for KIPT is also 82F, but was set in 1963. Expect to see some breaks of clouds across the Alleghenies and Central Ridge and Valley Region late this morning and this afternoon as a mdt low-level downslope northwesterly flow develops. Highs across the NW Mtns to the Central Ridge and Valley Region will range from the upper 60s to mid 70s. Nudging of the hourly grid temps 50-75 percent twd the latest 18/12Z NBM guidance appears to yield temps a few to svrl deg F too warm across the Central and NW part of the state.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Partly cloudy skies across the north...with areas of bkn cloud cover across the southern half of PA this evening will yield to the rapid return of a dual or multi-layer of clouds from the Ohio Valley as the llvl flow becomes southeasterly...and deep swrly flow develops aloft. Numerous showers will spread across the western mtns around or shortly after midnight...with scattered showers moving across the central Ridge and Valley Region between 06-12Z Thursday. There continues to be good agreement on a split-flow upper trough amplifying over the Eastern U.S. through the end of this week and into the weekend, with 500mb height anomalies reaching -2SD by 22/12Z. This will allow low pressure to develop and track northeast along a stalled frontal zone over the OH Valley on Thursday and into west-central PA/NY Thursday night into Friday. Significant backing of mid level heights and upper trough orientation going negative tilt should slow the system progression and support broad area of soaking rain along/behind the front. Favorable right entrance region jet dynamics and above normal moisture should also aid in producing moderate to locally heavy rainfall amounts. Followed WPC guidance for the most part with QPF amounts derived largely from GFS/EC blend. This resulted in a stripe of 1.5-2.5 inches for 36-hour total ending 00Z Saturday across the northwest 1/3 of the area. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Low pressure developing northeast of the Turks and Caicos (currently being monitored by NHC) is forecast to track northwest and then north ahead of the deep layer trough approaching the East Coast by the end of the week. The models show some differences concerning the possible interaction between this low and the aforementioned surface low with the CMC the most bullish. The full range of guidance suggests odds are slightly higher for the two system to remain largely separated with eventual consolidation and further deepening likely by the time the system reaches northern New England by early Saturday. This will result in a colder and brisk/gusty northwest flow pattern with some potential for wrap- around/deformation precipitation giving way to showery regime focused downwind of Lake Erie and over the higher terrain of the Alleghenies/Laurel Highlands. Surface-850mb temps will be marginally cold enough to support rain/snow showers Saturday (and especially Saturday night)over the NW mtns and Laurel Highlands with a low probability for a light coating Sat night at Elevations above 2200 ft MSL where some heavier bands of Lake Effect or Orographic showers occur. Some snow pellets are even possible just SE of the Allegheny Front in any brief heavier showers late Saturday afternoon and night as 850 mb temps dip to -2 to -3C. Also...ramped up wind (and wind gusts to a conservative 25-30 kts for now)- during the Saturday afternoon and evening period. Bufkit profiles indicate a deep boundary layer with the well mixed layer tapping some 35 to 40 kt wind at just 3-4 kft agl. GFS/EC show a fast- moving low diving through the Great Lakes into early next week. This system has low predictability given it weak state embedded within a progressive WNW flow aloft. Temperatures start off very mild for the later half of October but trend noticeably colder/below normal by the weekend. The roller-coaster up and down swing in temperatures is not uncommon for this time of year and will only continue as the calendar turns towards winter. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... A weak cold front will drift southeast across the region today, accompanied by some early morning light showers over the central mountains from KJST/KAOO/KUNV/KIPT. These will disappear before they reach the Susq Valley. Rain band is associated with cig reductions (mainly MVFR) which will linger into the mid morning. In addition, NW flow will bring MVFR reductions back into KBFD. For the afternoon, light NW flow and VFR will be the prevailing conditions. Developing low pressure area over the Ohio Valley will spread low clouds back into the western mtns Wed night on nose of increasing southerly low-level flow. A larger-scale rain event will impact the area Thursday into Friday night, bringing widespread reductions (with IFR likely north and west). Saturday looks quite breeze with a brisk NW wind likely. Outlook... Wed...Morning reductions NW and central mtns. Thu-Fri...Widespread reductions (with IFR likely N/W). Scattered showers SE, periods of rain elsewhere. Sat...Restrictions NW. Sct showers NW. Quite breezy. Sun...No restrictions. && .CLIMATE...
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New daily record maximum temperatures were set yesterday 10/18 at Harrisburg (84) and Williamsport (84) with a tie at Bradford (75). Daily record maximum temperatures appear to be in jeopardy today for a few climate sites. Here are the current records for 10/19: Harrisburg: 82 in 1945 Williamsport: 82 in 1963
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert SHORT TERM...Lambert LONG TERM...Lambert/Steinbugl AVIATION...RXR CLIMATE...Steinbugl is the U.S. government's official web portal to all federal, state and local government web resources and services.