Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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801 FXUS61 KCTP 211420 AFDCTP Area Forecast Discussion National Weather Service State College PA 1020 AM EDT Sat Sep 21 2024 .SYNOPSIS... A frontal system will fall apart as it moves into Central PA this afternoon and evening. It will make scattered showers and thunderstorms, a few of which may be severe. Drier weather returns for Sunday, before a slow-moving trough brings the next chance of rain from Monday through midweek. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... Temps heating up away from the stratus deck in the east. Surface winds out of the east will keep it more-stable in the east this afternoon and evening. The SPC MRGL risk for today remains as is, with the central and western zones still under a risk of severe, but mainly near-severe storms. However, a lightning risk is there for most of the area, so factor this into any outdoor activities you may have planned for the aftn/eve. The front i more an occlusion already and still back over OH. As the upper flow nudges it this way, storms will continue to fire up, but coverage should be sct for much of the time in the axis of best instability. As we get into the evening hours and early night, the upper low/storm off the coast will exert more influence and stall out the showers/storms, and the increasing stability from earlier rain and loss of daylight/heating should take away the thunder risk. Showers may linger (per most guidance) well into the night over the eastern half of the CWA. The near-severe threat also decreases in the evening, perhaps very early in the evening. && .SHORT TERM /10 PM THIS EVENING THROUGH SUNDAY NIGHT/... Model guidance indicates the shortwave and weak surface low pass east of the region tonight. A cold air damming scenario renews as the flow in the east remains from the east. Typical CAD sfc features make this pretty clear. Forecast soundings indicate an upsloping southeast flow will result in persistent stratus and perhaps a bit of fog or drizzle over the central/east zones for Sun and Sun night. The cloud cover and flow off of the Atlantic should result in markedly cooler afternoon temps Sunday than on Saturday, with highs likely stuck in the 60s over the Central Mtns. Sun night looks mainly dry with prev anticipated forcing holding off a bit longer/later. && .LONG TERM /MONDAY THROUGH FRIDAY/... Upper trough energy and wavy frontal systems will be kicked from the Plains/Midwest into the Great Lakes/Ohio Valley and northern Mid Atlantic next week. An associated threat of rain/showers will accompany these systems with some potential for heavier rainfall within an amplifying mid/upper level upstream flow pattern during the second half of next week. Given model variability/growing uncertainty by later next week, we did not identify any actionable targets of opportunity and therefore weighted forecast basis heavily toward the National Blend of Models (NBM). These data indicated a modest cooling trend from the 9/21 weekend warmth trending closer to climo (near or slightly below average) for daytime highs in the 60-70F range. Meanwhile, overnight low temps continue to run above the historical average for late September in the 50-60F range. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... Much of the area clear still. Lower clouds came into portions of the Susquehanna Vly. These clouds could break up for a while late morning into the afternoon hours. At the same time, showers and isolated thunderstorms across the far northwest, in the area with stronger warm advection. As noted by guidance, expect this activity to weaken some. This makes sense, as heating will be limited for a while. Most of the showers and storms would be later this afternoon into this evening. Some cloud be on the strong to severe side, as SPC has noted. As noted above, CIGS could go back up later this afternoon, but likely will fall into the IFR and MVFR ranges. Next week gets off to a cloudy start. Outlook... Mon-Wed...Scattered showers. && .CLIMATE... The high temperature in Bradford on Friday set a new record high of 82 degrees. This broke the record of 81 degrees set in 1978 and 2016. The first day of autumn 2024 (Fall Equinox) begins at 8:44 am EDT on Sunday September 22nd. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo/Tyburski LONG TERM...Steinbugl AVIATION...Martin CLIMATE...Steinbugl/Martin/NPB