Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 122050 AFDCTP Area Forecast Discussion National Weather Service State College PA 350 PM EST Tue Dec 12 2017 .SYNOPSIS...
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Low pressure forming off the northeast coast at mid afternoon will track northeast tonight and result in a deep northwest flow of cold air across the Great Lakes into Wednesday aft. This will result in snow showers across the mountains tonight and early Wed. Another area of low pressure will track across southwestern Pennsylvania Wednesday night. This low will bring a period of light snow to the area late Wednesday into early Thursday. A complex weather pattern will be across the region this weekend, and early next week. This will result in some snow showers from time to time, but a moderating trend into next week.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... The cold front has cleared our county warning area, winds have come around to the west/northwest with gusty winds. The cold air will continue to move in with with another 10C fall in the 850 hPa temperatures expected overnight. It will turn sharply colder over the next 8-12 hours and the gusty winds will add some additional windchill effects to the mix. Going out tonight or early tomorrow heavy winter coats, hats, and good gloves/mittens will be in order. Especially at the bus stops Wednesday AM. In our western areas, upslope snow showers will accompany the cold air in the higher terrain mainly from Somerset County up through Cambria and southern Clearfield. Some accumulating and blowing snow will be around. Some HRRR runs show enough QPF that at 20:1 would make 1-3 inches of snow. Perhaps a bit more in orographically favored areas in the next 18 hours. In the extreme northwest hour CAMS are more favorable for accumulating snow. Some HRRR runs shows enough QPF at 20:1 to produce 5-6 inches and HREFV2 implies higher amounts possible in northwesternmost Warren County. Our QPF and snow is higher than the CAMS. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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Key point is it will be a very cold day with lots of wind. Windchill values will be below 0F in the northwest and range the single digits above zero over the southeast. Bundle the kids up for school. A very cold December kind of day. Snow guns should be blazing at ski resorts. The snow should continue though at lesser rates in the northwest and in the higher terrain of the southwest mountains. Clouds will increase during the day as a fairly vigorous Alberta Clipper zips on towards us. Most models weaken it as it passes over us. But as the rule of clippers go this one should pass just to our south, the old school sweet spot. Most of the larger scale models imply 0.1 to 0.25 inches of QPF. Highest in southwest mountains, possible. Most of the potential snow will fall after this period. But the GEFS and SREF imply some snow could arrive in the southwest in the late afternoon or early evening. Most of the snow will fall after 7 PM. I did up QPF and POPS some Wednesday night. Amounts still below advisory. System is moving awful fast for much snow.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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Complex pattern for late in the week into next week. I did lower temperatures and dewpoints for the first part of the weekend, as the northern system looks stronger now, may result in cold air building southward into the area. Also cut winds and gusts down, as I have done the last few days, given the trend away from a deep low on Sunday. Models show southern branch of the westerlies trying to come into play on the large scale next week, but for now did not go real high with POPS.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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The cold front is still working its way across our easternmost counties. Behind the initial surge of cold air winds have come around to the west/northwest with gusty winds in the higher elevations. Gusty winds will slowly spread east. Low cigs are behind the front. But most of the MVFR/IFR is in the higher terrain. Snow and blowing snow will affect the southwestern mountains and northwestern areas for the next 12 to 24 hours. Blowing snow too. KBFD and KJST will be the two spots to check the weather carefully before take off. Most other areas main concern will be increasing and gusty winds. Some snow showers will affect KAOO and KUNV at times but nothing significant nor long lasting but periods of MVFR will happen. Farther east mainly gusty winds. A short wave could bring light snow into western areas Wednesday afternoon into Thursday. This could lower CIG/VIS in many western areas from KJST-KAOO-KUNV but this is beyond our current forecast period. Outlook... Wed...Snow showers with IFR NW Mtns. Sct snow showers with MVFR NW half. Otherwise VFR. Wed night...Alberta Clipper could bring light snow and more widespread reductions. Thu-Fri...Sct snow showers NW. Reductions west and southwest mts. Sat...Mainly VFR. Perhaps a snow shower north and east early. Sun...Mainly VFR. Perhaps a few showers late.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 1 PM EST Wednesday for PAZ005- 010-017-024-033. Lake Effect Snow Warning until 1 PM EST Wednesday for PAZ004. && $$ SYNOPSIS...Lambert/Martin NEAR TERM...Grumm SHORT TERM...Grumm/Martin LONG TERM...Martin AVIATION...Grumm/Martin

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