Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 161041 AFDCTP Area Forecast Discussion National Weather Service State College PA 641 AM EDT Sat Mar 16 2024 .SYNOPSIS... Temperatures will be unseasonably mild for the start of the weekend until a cold front ushers in a change by Sunday. The cold air will persist into the midweek period accompanied by a several bouts of snow showers over the Alleghenies and Laurel Highlands. Temperatures start to warm up again in the second half of the week. && .NEAR TERM /THROUGH TONIGHT/... Light NW sfc wind is keeping lower clouds piled up over the western high terrain. Only patchy clouds may be found SE of AOO-UNV. A low inversion in the morning will be erased in the afternoon, mixing the airmass up to 5-6kft. Most of the morning stratus will burn and/or slide to the east before more clouds slide into the wrn mtns this morning. Then, the deep mixing should zap those clouds with few clouds left to mar a mostly sunny day. The deep mixing and relatively dry air will probably take the dewpoints/RH below guidance in many places this aftn, more-so in the NE counties. Maxes are not going to be anywhere as warm as the last many days, but they will get milder today in the far NW (by ~1F), and still be 5-10F warmer than normal for all of Central PA. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Vorticity rounding the base (and stretching out) of a progressive upper low over nrn ONT will drag a cold front into the CWA and touch off a patch/line of rain showers this evening. The rain will press from NW to SE thru the night, and break up as it does since the moisture overhead will be unremarkable. Temps dip enough behind the front that anything lingering back behind it may mix with/turn to snow just as the flow becomes more lake-effect favorable. Not much QPF being produced by most models after 12Z Sunday, with the straight W-E llvl winds keeping most/all lake effect to our N. Subsidence also aids in drying things out, but clouds won`t go away Sun aftn/night. A gradual decrease in llvl temps will put the 8H temps down to -2C SE to -8C NW by late in the day Sunday. This cooling before a wave moves down from the NW on Monday may decrease the voracity of SHSN/SNSQ that day. But, an upper trough will be crossing the region during the daylight hours, and decrease the stability. See the prev discussion for more on Monday: Several distinct short waves and rounds of diff PVA will track SE from the Glakes and bring rather frequent snow showers and a few bands of heavier squalls to PA`s Northern and Western Mtns for much of the first half of the long term period, with brief snow showers making it into the Central Mtns and Middle Susq Valley at times. The bulk of medium range guidance then tracks a potent upper level shortwave and cold front through the region Monday. A round of snow showers/squalls could accompany the passage of this feature Monday. Strong large scale forcing, steep lower tropospheric lapse rates and even some CAPE are evident in some models with the fropa, signaling a potential of squalls. The middle and upper portion of the thick stratocu clouds will reside within the Dendritic Growth Zone across the Laurel Highlands and NW mtns Sunday night through Tuesday with sfc temps by day in the low to mid 30s and mins at night in the 20s. This temp profile will support light snow accums for much of the Alleghenies with localized accums of several inches, esp across the perennial snowbelt of Warren and NWrn Mckean Counties. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Still some model spread from day to day and run to run, to how the fcst plays out after Tuesday. Not real clear cut to how much warm up will occur mid to late week. Still looking like by late week it could trend rather wet again. Below normal temperatures and lake effect snow showers appear likely Tue/Wed, as upper level troughing and a cold northwest flow over the Grt Lks remains in place. Fair weather and moderating temperatures appear likely by next Thursday, as the upper trough begins to lift out. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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The low clouds which build in overnight will begin to diminish shortly after sunrise. The central and north west mountains are currently borderline MVFR/VFR, but conditions are expected to improve to VFR by mid morning. A west/southwesterly breeze will develop and gust 15-20 kts by afternoon ahead of an approaching cold front. Clouds will begin to increase from the northwest late in the day, as the front nears. Rain chances will begin for the NW near 00Z Sunday and gradually increase for the central mountains approaching 06Z. Some increase in LLWS is likely as the front moves through. Scattered rain showers are expected to overspread PA from NW to SE tonight associated with the passing of the cold front. Low ceilings and reduced visby is likely where rain showers are heaviest. Confidence is still low as to the exact timing of MVFR and lower conditions. As temperatures dip to near freezing in NW PA wet snow will mix in with the rain in the early morning hours of Sunday and into Sunday afternoon. Elsewhere should improve to VFR with overcast skies. Outlook... Sat night-Sun...Rain showers with MVFR cigs developing, primarily N/W PA. Some snow could mix in as colder air arrives on Sunday. Predominantly VFR elsewhere. Sun night-Tues night...Periodic snow showers and reductions across primarily N/W PA. Gusty W/NW winds areawide. Wed...Improving conditions.
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&& .CLIMATE... Astronomical Spring (vernal equinox) begins on Tuesday March 19 at 11:06 PM EDT. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Jurewicz/Lambert/Martin/Tyburski AVIATION...Bowen CLIMATE...Steinbugl

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