Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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742 FXUS63 KOAX 300449 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1149 PM CDT Wed May 29 2024 .KEY MESSAGES... - Shower and storms are expected to develop tomorrow morning, with a 5 to 15% chance for damaging wind and up to quarter- sized hail from 3 to 8 PM. - Showers and storms tomorrow will be slow-moving, and could rain heavily on locations and result in flooding. - There will be daily chances for rain/thunderstorms starting tomorrow and lasting through Tuesday. - There is increasing potential for strong to severe storms during the Sunday-Monday time frame.&& .DISCUSSION... Issued at 403 PM CDT Wed May 29 2024 This Evening through Tomorrow: Water vapor imagery this afternoon features two troughs sitting on either side of the Great Plains region, with the trough to the west beginning to tilt negatively despite its general shallow nature. Over the High Plains, upscale growth of showers and storms is beginning, but should not sustain itself and make it to easter Nebraska due to the generally poor moisture and shear in place locally. A surface analysis depicts a dryline/surface trough that the aforementioned storms are initiating from with a broad moist sector and thermal ridge to the east that gets more and more restricted spatially to the north by a leftover and now stationary front extending from western North Dakota to the southeast towards the Mid- Atlantic. Deep mixing has been ongoing today with the expectation that the shallow cumulus cloudcover that has developed to disappear shortly after sunset with lows expected to fall into the upper 50s tonight. With the front and trough to the northwest expected to begin approaching the area, stronger winds are expected to slowly creep into the area overnight, with gusts to 20 kts possible despite a healthy nocturnal inversion. By tomorrow morning moisture transport and warm air advection is expected to be in full force, roughly when the dying convection and its associated shortwave to the west drifts into eastern Nebraska. The combination of these elements are expected to result in increasing shower and weak storm chances by mid- morning, while daytime heating will further increase surface instability and as a result lightning activity. During the afternoon hours, those thunderstorms that do develop in the warm sector have storm motions on the order of less than 10 kts due to the weak shear and ambient wind speeds in the lower 5 km. Restricting the warm sector to the west will be a slow-moving cold front that will serve as the focus for more organized convection. While low-level hodographs feature good curvature, weak shear and large temperature/dewpoint spreads will limit tornadic potential. What seems more likely are spotty strong wind gusts of over 60 mph thanks to drier low-levels and pockets of severe hail through around 9 PM. Beyond that, chances for storms generally transition to sub-severe levels. Saturday and Beyond: For the weekend and beyond, storm chances are expected to continue well into next week as we fall into a summertime mid/upper pattern. With the mid/upper flow transitioning into a generally zonal pattern, southerly moisture will gradually creep northward along with warmer temperatures thanks to southerly winds being present at least for some part of each day. One signal that is being picked up on by several of the forecast models is the chances for a larger MCS to develop out of the western Nebraska Panhandle region and into eastern Nebraska/Iowa overnight Sunday into Monday. Aside from that, temperatures well into the 80s are set for the weekend into next week with each day playing host to additional rain and storm chances, including increasing chances for severe storms Monday/Tuesday as shear increases. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1141 PM CDT Wed May 29 2024 VFR conditions across the area this evening with winds out of the southeast. Showers and storms are approaching from the west and will move in overnight. Expect scattered showers and storms to move into northeast Nebraska overnight and spread across our area Thursday morning. They will be very scattered in nature and any thunderstorm activity will only impact one area for a brief period in time. Model guidance is all over the place with timing and location of these storms due to their scattered nature, so confidence is low in trying to forecast timing for when they will impact the terminals. Will likely need to just amened when we see them approach the terminals through the day on Thursday. Scattered showers and storms continue into Thursday evening, with some models showing cigs starting to lower to MVFR or even IFR after 00Z. Right now looking like only about a 20% chance, with greatest chance at KOFK where showers start to wrap up earlier (40% chance). && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Petersen AVIATION...McCoy