####018007898#### FXUS63 KGID 260628 AFDGID Area Forecast Discussion National Weather Service Hastings NE 128 AM CDT Fri Apr 26 2024 ...Aviation Update... .KEY MESSAGES... - High confidence in a widespread strong to severe thunderstorm event across much of the forecast area this evening/tonight. Many areas will see over 1 inch of rain, with localized 2 to 3 inch amounts. - Primary severe weather threat this evening/tonight will be golf ball sized hail and thunderstorm wind gusts to around 70 mph primarily along and south of I-80. There will also be an isolated tornado threat mainly in our southwest (Phillips, Rooks, Osborne Counties in Kansas). - Upper low will be slow to exit the area on Friday and thus another round of severe thunderstorms are possible Friday, mainly between 11 AM and 4 PM across our east and northeastern areas, including the possibility for isolated tornadoes in addition to hail and winds. - Expect a general lull in precipitation chances Friday night into at least the first half of the daytime Saturday. Thunderstorm chances will increase late Saturday afternoon into the evening, with more high end severe weather possible, especially from the Tri-Cities and points to the south and southeast. - Areas of frost are possible Sunday night, mainly to the northwest of the Tri-Cities as we cool down behind the departing storm system. && .DISCUSSION... Issued at 318 PM CDT Thu Apr 25 2024 This Evening/Tonight (Severe Weather)... The warm front will gradually lift north and could make it into our far southwestern counties (Rooks, Osborne, Phillips) by around or just after sunset. The tornado threat will be limited to areas in close proximity to this warm front across our far southeastern zones where storms may become surface based. Thunderstorms will quickly develop southwest of our forecast area late this afternoon and then track east northeast into our southwestern areas primarily after 7 PM. These storms will then continue to track across our forecast area bringing possible severe weather and likely heavy rain at times through the late night/early morning hours. There is some question as to where the southern most extent of the line of thunderstorms will set up. All of south central Nebraska is pretty much expected to get in on these thunderstorms tonight, but it is more questionable how far south they will extend into north central Kansas. But even Kansas rain chances are 70-80 percent with near 100 percent rain chances across south central Nebraska. Added the possibility for locally heavy rainfall including localized flash flooding to our forecast as thunderstorms could train over the same locations tonight. Although surface based instability/CAPE is lacking, there is plenty of MUCAPE at over 2,000 J/KG ahead of these thunderstorms tonight, especially along and south of I-80. Therefore, large hail is certainly possible and can also not rule out some stronger wind gusts making it to the ground behind bowing lines of thunderstorms. Friday (Severe Thunderstorms East and Northeast)... The upper low is slow to exit the area and as it slows down from previous runs we have seen the SPC severe outlook expand further and further back to the west on Friday to include more of our forecast area with higher threat levels. There is a concern for tornadoes near the low across our eastern and northeastern zones as the warm front lifts north during the late morning and early afternoon hours. There will be little to no CIN in close proximity to the low, so thunderstorms could redevelop very quickly around noon or shortly thereafter. I would not be surprised to see the future severe outlooks bring the Friday tornado potential even further west into our forecast area. Eventually the surface winds will turn southwest by later in the afternoon as the low lifts northeast and the severe weather threat will pass off to our east and northeast. Greatest severe weather threat across our northeastern zones will be between noon-4 PM. Saturday (Another Severe Weather Threat)... The next upper low is quick to eject into high plains by Saturday afternoon/evening. The main question will center around where the warm front sets up, but current indications are that the warm front will be located somewhere across the southern half of our forecast area. The atmosphere will again be very unstable along with strong wind shear. All forms of severe weather including tornadoes will be possible in the warm sector northward to around the warm front. Large hail will be the primary severe weather threat north of the warm front. The forecast may certainly change as this is a few days away, but keep an eye on where that warm front sets up Saturday afternoon. Sunday into Sunday Night (Cooling back/frost?)... We will cool down behind the departing storm system. Some showers and thunderstorms could linger into Sunday, but the main concern will be possible frost northwestern areas as we clear out Sunday night. Monday through Wednesday (Warming back up)... Great weather returns with most locations seeing highs back into the 70s. There are some small rain chances (20-30%) Tuesday afternoon through Wednesday, but not looking like a big deal at this point. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 127 AM CDT Fri Apr 26 2024 UP FRONT NOTE REGARDING KEAR: Have tagged KEAR TAF with "AMD NOT SKED" (amendments not scheduled) given temporary loss of observations. - General overview for KGRI/KEAR: This is a somewhat complex period, as a strong low pressure system passes through the region from southwest to northeast, accompanied by several aviation concerns including: sub-VFR ceilings, showers and thunderstorms (and associated sub-VFR visibility), breezy to moderately-windy winds and a gradual directional shift from southeasterly, to southwesterly, to westerly. - Ceiling/visibility/rainfall/thunderstorm details: Although showers and (probably) non-severe thunderstorms will remain possible at almost any point through these first 18 hours (and have at least a VCTS or VCSH going throughout this time, the most concentrated activity will be right away these first 3 hours, which is handled with a TEMPO group for TSRA and visibility potential down to around 2SM. Truly severe thunderstorms are not anticipated, but periods of brief heavy rain, wind shifts and possibly small hail are all possible. As for ceiling, they are currently "all over the place" due to convective influences, but particularly the 09-18Z time frame will likely feature prevailing IFR/MVFR before ceilings rise to at least low-end VFR during the afternoon. - Wind details (not accounting for any convective influences): For the majority of the period, sustained speeds will average 15-25KT/gusts 20-30KT, with sustained speeds finally easing under 15KT by very late in the period (beyond 03Z). Direction- wise, passing low pressure will result in a gradual/general shift from east-southeasterly this morning, to southerly mid- morning to early afternoon, to southwesterly mid afternoon, to westerly late afternoon and evening. On one final wind-related note, considered introducing a marginal low level wind shear (LLWS) group for early this morning, but with shear magnitude within the lowest 2K ft. AGL looking to average closer to 25KT than 30+KT, held off on formal TAF inclusion. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ DISCUSSION...Wesely AVIATION...Pfannkuch ####018005318#### FXUS61 KILN 260628 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 228 AM EDT Fri Apr 26 2024 .SYNOPSIS... High pressure over the Great Lakes will move east today, with dry weather continuing for the Ohio Valley. A warming trend will begin on Friday, as an upper level ridge moves east of the region. Precipitation chances will increase starting on Friday afternoon, with a warm front moving into the area. && .NEAR TERM /THROUGH TONIGHT/... Surface high pressure is centered over southern Ontario, with light ENE flow over the middle Ohio Valley. Mostly clear conditions are expected through the near term. With a dry air mass and mostly clear skies, tonight will be somewhat favorable for falling temperatures and frost development. The one limiting factor is the wind flow, which will not go completely calm. With that in mind, freezing temperatures are not generally expected, and temperatures cold enough for frost will only impact less than half of the forecast area tonight. A Frost Advisory was coordinated with surrounding offices and issued for parts of west-central and central Ohio. && .SHORT TERM /SATURDAY/... At 12Z Friday, high pressure will have moved east into New England, and a mid-level ridge axis will be just upstream of the ILN CWA. As this axis moves east, SSW flow on its back side will begin an increase of theta-e into the area. While there may not be a very well-defined surface front, moisture convergence and theta-e advection at 850mb will be more pronounced, and a band of showers (with possibly some embedded thunderstorms) will move into the area late in the afternoon and into the evening. Precipitation chances appear highest in the northwestern ILN CWA, where the forcing is a little bit stronger. Behind this initial wave of precipitation, chances will continue into the overnight hours, but they will be much more spotty and limited. Temperatures should warm appreciably before the thicker clouds and precipitation move in Friday afternoon, with highs reaching the upper 60s to mid 70s -- with the warmest temperatures in south-central Ohio and northeast Kentucky. There is some potential for this area to reach the upper 70s tomorrow. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... The first of two mid level shortwaves will be moving off to the northeast and the band of showers associated with the warm front from this system will have progressed out of the area. This leaves us in a warm airmass with strong southerly flow as ridging moves in aloft. Breezy southerly winds remain in place and we gust to 30 MPH or so on Saturday. Since there aren't any synoptic or mesoscale forcing mechanisms for ascent moving through, so we're not expecting widespread precipitation at this time. However, diurnally driven storms may be possible through the daytime hours Saturday. High temperatures reach the low 80s. Overnight lows into Sunday fall into the mid 60s with mostly dry conditions continuing. The strength and positioning of the ridge continue to contribute to the ongoing warming trend. Highs on Sunday reach the low 80s, with low chances for an afternoon popup storm. By the start of the work week, the secondary shortwave begins to open up and move northeast with the surface system moving northeast through the Plains. High clouds begin to build in on Monday and precipitation chances begin to increase as the weak cold front marches toward the region. Have Likely PoPs in for Monday overnight into Tuesday, but overall forcing isn't robust. High temps anticipated to be only a tad cooler on Tuesday, with highs in the upper 70s. Rain chances decrease in the post- frontal air for Tuesday into Wednesday, but quickly return as yet another shortwave begins to move toward the area in the larger flow. Have periodic chances for PoPs in the forecast through the remainder of the week in the unsettled pattern. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... High level clouds to continue to spill into the area today as a mid level ridge builds across the area. As the ridge axis shifts to the east moisture will increase late in the day into this evening. Clouds will thicken and lower while ceilings remain VFR this afternoon as the mid level ridge axis shifts east and the flow backs southwesterly. The favorable lift will results in a band of showers and embedded thunderstorms that pivots north thru the area late in the day into this evening. Have a mention of VCSH for this pcpn band but brief MVFR conditions will be possible in rain showers. East winds at 10 kts or less early will become southeast at 10 to 15 kts this afternoon with gusts up to 20 kts. OUTLOOK...MVFR conditions are possible on Saturday. Thunderstorms are possible Monday night into Tuesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Frost Advisory until 9 AM EDT this morning for OHZ026-034-035- 043>046-052>056-063>065-073-074. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Coniglio/Hatzos SHORT TERM...Hatzos LONG TERM...CA AVIATION...AR