Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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723 FXUS63 KOAX 230436 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1136 PM CDT FRI JUL 22 2016 .SHORT TERM...(tonight through Monday) Issued at 335 PM CDT Fri Jul 22 2016 12z Upper-air analysis revealed a mid-level high centered over northern Oklahoma/southern Kansas with a ridge axis extending northwest through the northern High Plains to the lee of the Canadian Rockies. Immediately upstream from this ridge was a polar-branch short-wave trough over the Pacific Northwest. In the low levels, early afternoon mesoanalysis indicates a weak front/trough stretching from northwest Iowa through northeast and south-central Nebraska into northwest Kansas. Similar to yesterday afternoon (albeit farther south), radar and satellite data indicate a mesoscale convective vortex (MCV) over northwest Kansas with a downstream corridor of elevated convection observed from south-central into southeast Nebraska. While the bulk of this convection may settle south into Kansas, at least isolated storms will remain possible into this evening across portions of southeast Nebraska. Elsewhere tonight, both parameterized and convection-permitting model guidance remains quite dispersive in the areal coverage and location of convective precipitation. A weak perturbation over Wyoming this afternoon will crest the mid-level ridge axis over the mid Missouri Valley tonight before shifting east of the area Saturday. Conceptually, forcing for ascent (DCVA) associated with this feature in conjunction with strengthening warm advection along the nocturnal LLJ should increase the odds of MCS formation tonight somewhere to the west and north of the aforementioned surface boundary, warranting highest POPs across our northern CWA. On Saturday, areas of clouds and isolated storms may linger through part of the morning before giving way to another day of hot and humid conditions ahead of a cold front approaching our area from the northwest. As a result, we will be extending the excessive heat warning until 7 PM Saturday. The cold front will advance southeast through eastern Nebraska and western Iowa Saturday night into early Sunday with a slight chance of thunderstorms along and ahead of it. High temperatures on Sunday will be cooler (most noticeably so across northeast Nebraska),ranging from mid 80s north to lower 90s south. Sunday night into Monday, we begin to see larger model spread in the location of the low-level baroclinic zone which will stall to our south. Given the uncertainty, we will only include slight chance POPs over southern parts of the area. .LONG TERM...(Monday night through Friday) Issued at 335 PM CDT Fri Jul 22 2016 12z Medium-range guidance remains consistent in suggesting that the upper high currently to our south will retrograde into the southwestern U.S. during the middle to latter part of this upcoming week. A resultant transition to northwest flow aloft will occur over the north-central states with several embedded perturbations traversing the mid Missouri Valley, along with multiple frontal passages. Consequently, there will be a chance of thunderstorms through much of the extended period with near or slightly below normal high temperatures. && .AVIATION...
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(For the 06Z TAFS through 06Z Saturday night) Issued at 1135 PM CDT Fri Jul 22 2016 Current TSRA in southwest Iowa will probably not affect KOMA...but will need to be watched. It is looking more like there will be some TSRA later tonight as current activity to the west moves/develops eastward. Will include some mention of TSRA at all three sites...with a two hour window where storms appear most likely.
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&& .OAX Watches/Warnings/Advisories... NE...Excessive Heat Warning until 7 PM CDT Saturday for NEZ011-012- 015>018-030>034-042>045-050>053-065>068-078-088>093. IA...Excessive Heat Warning until 7 PM CDT Saturday for IAZ043-055- 056-069-079-080-090-091. && $$ SHORT TERM...Mead LONG TERM...Mead AVIATION...Miller

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