Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 241051 AFDCTP Area Forecast Discussion National Weather Service State College PA 651 AM EDT Tue Apr 24 2018 .SYNOPSIS... A slow moving area of low pressure will produce a period of rain for today into Wednesday. Expect dry but still cooler than normal conditions on Thursday, but a brief shot of rain is possible Friday or Saturday. Then, another stretch of dry weather begins and lasts into next week as a huge high pressure area moves in from the west. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... Beautiful sunrise - red in morning. Lots of radar returns but barely sprinkling. Still T/Td depressions of 12-20F this hour. So, it is going to take a while to make it moist and get efficient rainfall to occur over the east. The west is best - for rain - today. Have trended POPs toward the latest HRRR/RAP blend, slowing the eastward progression of the rain by several hours. Prev... Arc of rain lifting through the central mtns is starting to fall apart. The stronger reflectivities must be bright-banding as they are right in that zone. Rain continues to fall apart a little as it lifts north. More-coherent and better-forced rainfall is not far behind this first volley, though. Prev... Radar shows a minor first volley of moisture/forcing moving into/through the Laurels at 1 AM. T/Td depressions of 20+F mean it could take a little bit of time for the rain to work down from aloft. An upper low and it`s attendant sfc low are currently sitting over the TN Valley with a occlusion stretching to a triple point over GA. The low closer to the coast will deepen through the day as it moves into the Carolinas. The system/pattern is very disorganized and things just don`t look like they are phasing up at all. 3 or 4 different vort maxes will be spinning over the eastern U.S. today, and none will help the other out. Good srly/serly lljet will continue to increase the moisture through the day. The second volley of rain should succeed in making most of the area wet by sunset. It may take all day to get into the NE mtns as the upper low doesn`t get too close (Smokies) by sunset. Temps pretty mild at 1 AM, especially considering the past few weeks. However, they might not change much or even dip some in the Laurels due to the rain/evap cooling and clouds. The eastern zones could tack on 15F to morning temps as the rain will advance only slowly eastward. && .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Main area of precip will likely be from the deformation zone/WCB circulation to the northwest of the deepening sfc low. The low will pass right over NJ on Wed. As the low moves to the north along the coast, dry air will get pulled in from the NW. The rain should be tapering off in the east during Wed AM. Other than some SHRA over the NW and very highest elevations of Somerset Co thanks to a ill-timed upper trough, the SE half of the area should dry out nicely. The NW should dry out Wed evening. Temps will dip into the 40s for everyone tonight. The downslope and extra sun will help the SE get into the 60s, but the rest of the area will be in the 50s in the afternoon without much sun. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... The Thursday to Saturday period should be mainly dry with just one potential weather-maker. That would be a northern-stream short wave trough - or a southern stream coastal low like the current one. Lots of uncertainty for Day3-4 right now. But, that would be the only wet time until well into the middle of next week. Temperatures will average near to slightly below average during most of the period before trending noticeably warmer into the first week of May. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Band of mainly light rain to the west falling apart now. Main change to the 09Z TAFS was to adjust fcst some for this band. Low pressure lifting out of the southeast states will spread lowering and thickening clouds across central PA later today. A few rain showers are working into the western airfields early this morning. However, due to dry air at low levels, expect VFR conditions to prevail. Expect deteriorating flying conditions from SW to NE late today, as the storm system and associated rain lifts up the east coast. The biggest impacts will be over the southwest portion of the forecast area, where model soundings and SREF prob charts support IFR cigs/vsbys by early evening at KJST/KAOO. The most favorable conditions will likely be in the vicinity of KIPT, where VFR conditions will likely hold until evening. Outlook... Wed...AM rain/low cigs likely, then PM improvement. Thu...AM low cigs possible W Mtns. Fri...Slight chance of rain/low cigs. Sat...AM showers/cig reductions possible NW Mtns. && .CLIMATE... April 2018 currently ranks in the top 10 coldest on record (through the 22nd). Seasonable temperatures are expected through the end of the month which should help to balance the cold start. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Steinbugl AVIATION...Martin CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.