Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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521 FXUS63 KOAX 021115 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 615 AM CDT Tue Jul 2 2024 .KEY MESSAGES... - Scattered strong to severe thunderstorms are expected this afternoon and evening across portions of southeast Nebraska and southwest Iowa. The primary hazard will be damaging winds, though a tornado or two cannot be ruled out. - Additional rounds of thunderstorms will be possible Wednesday night and Thursday afternoon/evening. The storms on Thursday may also be on the stronger side. - A third system will bring another potential round of rain and thunderstorms to the region this weekend. These storms are not expected to be severe at this time. && .DISCUSSION... Issued at 339 AM CDT Tue Jul 2 2024 Today and Tonight... Scattered showers along and south of the I-80 corridor are expected to linger through mid-morning, particularly across portions of southwest Iowa. By noon today, the primary upper level disturbance will be centered over the northern High Plains, with an embedded low-amplitude short wave ejecting out into the central Plains at the same time. At the surface, a low-pressure is expected to be somewhere in southeast Nebraska, likely near US-80 south of I-80. South out of the low a cold front will extend down into Kansas, with a warm front draped across east-central Nebraska and into central Iowa. Sometime between noon and 2 PM this afternoon, thunderstorms are expected to initiate along these boundaries. While there may be a brief period of time (within an hour or so of initiated) storms may remain semi discrete, quick upscale growth into a line or bowing segments is expected with shear vectors parallel the cold front. A modestly unstable warm sector with SBCAPE ranging from 1500 to 2500 J/kg in addition to bulk shear magnitudes approaching 60 knots will help these storms become strong to severe within a couple hours of initiating. By this time, storms will likely extend along a line from Fairbury to Missouri Valley. Due to the weak capping in version project across the warm sector this afternoon, additional isolated strong to severe thunderstorms will be possible ahead of this line. Over the course of the afternoon and evening, these storms are expected to push east- southeast across southeast Nebraska and southwest Iowa. The primary hazard will be winds up to 70 mph, though hail up to golf balls (particularly earlier in the afternoon) and a brief tornado or two cannot be ruled out. The severe potential should push out of our area by 8 PM, thought synoptic forcing for ascent associated with PVA from the primary upper-level disturbance may help showers and non-severe thunderstorms linger across eastern Nebraska and western Iowa into the early overnight hours. Tomorrow and Thursday... A high pressure system is expected to traverse the central Plains tomorrow during the day. As such, mostly sunny skies and highs in the 80s will be on tap for much of the area. Wednesday evening, thunderstorms are expected to develop off the high terrain in portions of the central and northern High Plains. These storms are expected to move into our area after midnight tomorrow night in the form of a decaying MCS. These storms are not expected to be severe at this time, though gusty winds and small hail will be possible. Scattered showers and thunderstorms may linger through the morning hours on Thursday. On Thursday, another potent shortwave trough is expected to eject out into the central Plains. A cold front will move through eastern Nebraska and western Iowa sometime during the afternoon/early evening hours. By mid-afternoon, scattered thunderstorms are expected to develop along this front and push to the east. With CAPE on the order of 1000 to 2000 J/kg and bulk shear between 50 and 60 knots, strong to severe thunderstorms will be possible again. Recent model runs do trend this system a little more progressive than prior solutions. As such, we may continue to see the primary risk for strong to severe thunderstorms push east and south over the next couple forecast cycles. But for now, the main region that may see these stronger storms will be along and east of US-77. The primary hazards with these storms will be hail up to quarters and wind gusts up to 60 mph. The bulk of convection should push east into Iowa and Missouri by 7 PM. However, with still some changes to timing from model run to model run the last few forecast cycles, the exact timing of these storms may be adjusted over the next day or so. Friday through Tuesday... Friday another high pressure is expected to build into the region bringing mild weather and highs in the 70s. By the weekend however, another trough is expected to traverse the central and northern Plains bringing more unsettled weather. At this time, there is enough difference in models runs to make it difficult to pin down exact timing. Nonetheless, there will be some chance for isolated to scattered thunderstorms across portions of eastern Nebraska and western Iowa both days this weekend. These storms do not appear to be severe at this time. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 607 AM CDT Tue Jul 2 2024 A frontal zone currently transects the forecast area, roughly along a line from Albion to Sioux City. This front will slowly move to the southeast over the course of the day. Ahead of this front, winds will be southerly from 5 to 15 knots. Behind the front, winds will become north/northwesterly at 10 to 20 knots. This change in surface winds will take on the order of 1 to 2 hours as the surface front passes through. Scattered light showers will persist this morning through 16Z along the I-80 corridor (KLNK and KOMA). Scattered thunderstorms are expected to develop along and ahead of the front by 19Z (KLNK and KOMA). A few storms may be severe with quarter sized hail and wind gusts up to 65 knots. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Darrah AVIATION...Darrah