Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 221547 AFDCTP Area Forecast Discussion National Weather Service State College PA 1147 AM EDT Thu Jun 22 2017 .SYNOPSIS...
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A warm front will move through the region today, bringing a return to warmer and much more humid conditions this afternoon right through Friday night. A cold front will push east across the region during the morning or early afternoon hours Saturday, followed by drier and cooler air with comfortable humidity that will last through much of next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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The small MCS that moved through the Laurels early today has dissipated. Some new convection is beginning to form over NE Ohio moving into NW PA. The HRRR dissipates these lead cells in favor of new convection mainly after 18Z. Dewpoints have surged into the mid and upper 60s rather quickly with the approach and passage of the diffuse warm front. We will stay in the soupy airmass for at least the next 36-48 hours before drier air returns to the region. SPC has much of the northern portion of the region under a Marginal Risk. Instability at this time is limited at best, but model guidance does show the development of at least moderate CAPE and shear over much of the western part of the state as the afternoon warms up, and with dewpoints climbing this looks reasonable. The HRRR increases the threat for rain from mid afternoon into the evening, but coverage looks scattered at best. Sfc-1km EHIs climb to between 1.5-2 m2/s2 across the NW mountains during the afternoon, so we will have to stay alert for the potential of mesocyclonic formation in some of the stronger updrafts. Well mixed model soundings and mean 850mb temps around 16C should translate to afternoon max temps from around 80F over the northwest mountains, to the upper 80s across the Lower Susq Valley. Localized heavy showers and thunderstorms today will lay the groundwork/lower FFG values and additional and potentially training convection that will occur Friday, and through Friday night as moisture from Tropical Storm Cindy surges into the NE US.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... The main focus for convection this evening should be close to the best llvl theta-e convergence and moderate 0-1km shear near the northward advancing warm front that is expected to extend from the NW mtns to the Susquehanna`s West Branch Valley. After 01-02Z, convection should temporarily settle down/lift north into New York State as a weak mid/upper level ridge drifts overhead with a decent mid level cap of around 8-9C blanketing the state. Min temps tonight will be in the mid 60s to l70s with sfc dewpoints tucked in close below - leading to quite a muggy night with variable amounts of clouds at multiple levels, along with patchy late night fog. Friday into Friday night will be the most active weather period of the next 7 days as increasing large scale lift/vertical shear ahead of a potent northern stream trough interacts with the deep tropical moisture and high pwat air in place across the state. SPC has a Marginal Risk painted for all of the state given these factors, and a cold front that will approach the region early Saturday. Basin average rainfall for the 42 hour period late today through early Saturday ranges from around 0.75 of an inch across the east, to between 1.5 and 2.25 inches across the Laurels and points just to the west toward KPBZ. Training Showers and TSRA in this moisture rich environment could quickly increase the Flash Flood potential friday into Friday night, but for now no flags will be issued. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... From a large scale perspective, the medium range forecast will feature a seasonably strong/amplified upper trough settling over the Northeast U.S into next week. Expect moisture/rainfall associated with the remnants of TS Cindy to exit the area by the mid to late morning hours Saturday. Drier, low PW air arrives for the late morning and afternoon hours Saturday and lasts through the weekend. This should translate into comfortable, low- humidity conditions with temperatures near to slightly below late June climatology. Precipitation opportunities will be modulated by several shortwave impulses which have low predictability at this range. Any rains would be generally scattered and on the lighter side given overall lack of deep layer moisture. 21/12z GEFS shows PW values remaining below average into midweek. Temperatures should stay on the cooler side of climo through midweek as the upper level trough shifts east of the area. FWIW the GFS is more bullish vs. EC on heights rebounding/building SE U.S. upper ridging into the second half of next week. That said, there is general agreement in a modest warming trend later next week as the trough moves out and heights return to normal. && .AVIATION /16Z THURSDAY THROUGH MONDAY/...
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Patchy early morning clouds have burned off with all central PA terminals VFR as of 11AM. A warm front will help trigger showers and scattered thunderstorms this afternoon, mainly over the west and NW, with storms tending to fade after sunset. There will be a better chance for IFR conditions tonight into tomorrow as warm, humid air overtakes the region. .OUTLOOK... Fri...Widespread sub VFR likely with rain and embedded thunderstorms. Sat-Sun...Mainly VFR Mon...Mainly VFR. Chc SHRA/TSRA.
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&& .EQUIPMENT... KCCX radar will be offline for approximately 4 days starting Saturday, June 24th for technicians to install the first of 4 major service-life extension upgrades. The work on the radar has been scheduled to minimize potential impacts to operations and will be delayed if hazardous weather is forecast. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...Lambert/Steinbugl AVIATION...La Corte/Ceru EQUIPMENT...

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