Area Forecast Discussion
Issued by NWS State College, PA

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123 FXUS61 KCTP 231544 AFDCTP Area Forecast Discussion National Weather Service State College PA 1044 AM EST Thu Feb 23 2017 .SYNOPSIS... Our extended period of very mild weather will continue into Saturday. A strong cold front will push east across the region and bring showers, and perhaps a narrow line of gusty strong thunderstorms on Saturday. Gusty westerly winds, colder temperatures, and snow showers across the western mountains will follow the frontal passage for later Saturday into early Sunday. A relatively wave of low pressure moving northeast up the Ohio River Valley Monday may bring a few periods of light snow, mixed with rain in the valleys of Central and Southern PA. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... Small showers going through Happy Valley will dissipate slightly. But, the cloud/no-cloud interface and diff heating due to it will create the possibility for showers and perhaps a thunderstorm as it slides to the east this afternoon and early this evening. Have kept mention of thunder for the SE later today, but not over the rest of the area. Prev... Another very mild early morning for late February with temperatures ranging from the mid 30s to lower lower throughout the Susquehanna Valley and Central Mtns, to the balmy l50s across the cloud-covered western mtns where a weak upslope flow was helping to create a bkn-ovc layer of stratus. However, nothing more than some patchy drizzle and ridge top fog is expected across the NW Mtns and Laurels early today. plenty of Low clouds and mid-level moisture will make today another struggle to see the sun. However, the extremely mild start to the day (45-50F west and 35 to 40F in the east) will yet again allow the temps to be very much above normal through the whole day. A shearing "cold" front will dip down into the northern tier late in the day before stalling out near the PA/NY border overnight. POPs are a difficult call but trended to a blend of the HRRR and rather high and extensive Nat`l Blend of Models pops. Any fog this morning across the eastern zones should take a while to burn off with dewpoints so high. The warm sector and the passage of a very subtle short wave trough may pop some showers (and given several hundred J/KG of cape so early in the season - isolated thunder) over western PA and allow them to advect to the east during the aftn. The warm front itself will be another focus for some convergence and sct showers/possible TSRA. Max temps today will be even warmer than (Wed). 60s should be widespread with the warmest numbers in the south. && .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM FRIDAY/... The front will probably stall out for a short time tonight across nrn PA, but likely push northward as a warm front very late tonight and Friday morning. This feature will keep clouds around, and is yet another reason to remain very high on temps for tonight. Mins will again be between 45 and 50F area-wide. Very mild temperatures will persist for the end of the week, likely reaching records levels at least in some locations once again Friday afternoon as a gusty south to ssw wind advects warm and relatively moist air up from the south. Precipitation chances will be quite low across the south on Friday (where periods of sunshine will be mixed with varying amounts/thickness of cirrus clouds), while the northern tier counties of the state should see scattered showers during the monring hours. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Upper ridging over the east coast at the start of the period will be temporarily squashed as a decent northern stream shortwave moves east through the Ohio Valley and across the Middle Atlantic states over the coming weekend. This will bring a pronounced cold front across the region during the day Saturday. Heights are forecast to rebuild across the eastern half of the conus early next week ahead of troffing developing over the Rockies. The aforementioned cold front will return temps to near or closer to near seasonal normals for Sunday into early next week. Several shortwaves withing the developing southwest flow aloft will bring several weak fronts across the region. This will lead to less than pristine sky conditions...but the time period will be generally dry. However, enough low pressure lurking at the surface could lead to a system of more significance sometime during the week. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... Fog and low clouds are dissipating as expected in the SE. BFD is holding with a the LIFR cig. Will slowly improve BFD as upstream obs indicate better mixing. Prev... At 7 AM, some low clouds and fog to the east and west, but much of the area is not bad. 12Z TAFS sent. Earlier discussion below. A wide range of conditions at 5 AM. Some dense fog the last few minutes at LNS. Mid level clouds across much of the area has limited low clouds and fog formation. Coolest readings to the east. Expect conditions to improve some today, as a low pressure system lifts northeast across the Great Lakes. Perhaps a few showers across the northwest. A deeper low will track across the Great Lakes late Friday into Saturday. While temperatures will be on the warm side, dewpoints are not fcst to be real high, which may explain why the models have most of the rain on the back sice of the cold front. Outlook... Fri...IFR/MVFR psbl early - mainly N. Chance of rain mainly N. Sat...LLWS. Strong FROPA with sub-VFR likely in moderate rain showers and sct TS. Post-frontal WNW wind gusts 25-35kts. Sat night-Sun...Sub-VFR NW third with sct shsn. Gusty NW wind. Mon...Reduced CIGs psbl in RA/SN. && .CLIMATE... ***February Warmth 2017*** Updated 2/22/17 at 8am EST Record high temperatures for select sites for Feb. 23-24: ---------------------------------------------------------- Harrisburg 2/23: 70 in 1985 Harrisburg 2/24: 75 in 1985 Williamsport 2/23: 70 in 1985 Williamsport 2/24: 71 in 1985 Altoona 2/23: 66 in 1977 Altoona 2/24: 69 in 1985 Bradford 2/23: 57 in 1977 Bradford 2/24: 59 in 1961 ----------------------------------------------------------- Most 60 degree days in February at Harrisburg. Based on the latest forecast, add 4 more days to the list and finish tied for second with 7 days. 1. 10 days in 1976 2. 7 days in 1930 3. 5 days in 1991, 1943 5. 4 days in 1997, 1985, 1954, 1939 9. 3 days in 2017, 2016, 1996, 1990, 1961, 1932, 1890 ------------------------------------------------------------ Warmest February on Record (Avg. Temperature through 2/21) Harrisburg: 2017 rank=4 (38.6) 1. 40.4 in 1998 2. 39.6 in 1976 3. 39.4 in 1954 Williamsport: 2017 rank=4 (35.4) 1. 37.0 in 1998 2. 36.1 in 1954 3. 35.6 in 2002 Altoona: 2017 rank=2 (36.5) 1. 37.4 in 1976 Bradford: 2017 rank=6 (29.3) 1. 32.3 in 1998 2. 30.1 in 2002 3. 29.6 in 2012 4. 29.5 in 1990/1976 ------------------------------------------------------------- && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Dangelo/Lambert SHORT TERM...Lambert LONG TERM...Lambert/Gartner AVIATION...Martin CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.