Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 191150 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 650 AM CDT Fri May 19 2017 .SHORT TERM...(Today through Sunday) Issued at 347 AM CDT Fri May 19 2017 The continued chances for showers and thunderstorms through Saturday, and the potential for heavy rain, are the primary forecast concerns. Upper low was still spinning in the Central Rockies this morning, ejecting periodic shortwaves into the Plains. We will continue to see episodic bouts of rain and potentially thunderstorms until upper low lifts northeast of our area Saturday night. One of those shortwaves brought widespread showers and thunderstorms to our area overnight, but was lifting northeast this morning and taking most of the precipitation with it. Rainfall estimates from radar were generally around an inch over a good part of eastern Nebraska and southwest Iowa, with a few pockets over an inch and a half. These totals were well below 3-hour flash flood guidance numbers. And while that flash flood guidance will come down a bit given latest rainfall, expected additional rains through this evening are less than what happened this morning, except for perhaps southeast Nebraska. Thus much of our current flash flood watch will be cancelled this morning. The evolution of precipitation occurrences for today is a little less defined this morning than it was yesterday at this time. Although most of the heavier precipitation is moving off to the north and east, pockets of showers and isolated thunder continue to pop up from central Kansas into southern Nebraska. Thus am having a tough time defining dry areas/periods into the early afternoon. Therefore will maintain at least a small chance for showers all areas today. Better chances for precipitation will come late this afternoon and evening when another impulse ejects through the region, sparking convection near surface front in south central Kansas. Showers/storms will lift north into eastern Nebraska and western Iowa by late afternoon, becoming more elevated as it moves away from surface instability axis ahead of Kansas front. However southeast Nebraska and southwest Iowa will be in area where elevated instability and layer moisture profiles will be more robust, thus a better chance for thunderstorms and heavy rain. Meanwhile Rockies upper low will begin to push toward the Plains, cooling mid levels and providing forcing for showers and isolated thunder over much of our northern CWA as well. Upper low tracks across northeast Nebraska during the day Saturday, maintaining shower chances over all of eastern Nebraska and southwest Iowa at least through the morning. Dry slot pushing into southeast Nebraska Saturday afternoon should be the beginning of the end of this round of rain, with diminishing chances for precipitation from south to north Saturday evening. Temperatures will remain rather cool with clouds, precip, and northeast to north winds keeping lows in the 40s and highs in the 50s through Saturday. More sunshine under rising heights should push highs back into the 60s on Sunday. .LONG TERM...(Sunday night through Thursday) Issued at 347 AM CDT Fri May 19 2017 The dry period on Sunday will be short-lived as upper low lifts through the Plains but then stalls just north of the Great Lakes on Monday. Then a strong mid level trough drops south from Canada on the west side of low and into the Plains Monday into Tuesday, dragging upper low into the Ohio Valley region. This scenario puts our area under the influence of cyclonic flow regime with a couple of mid level impulses triggering shower chances the first half of the week, with temperatures on the cool side of normal. Models differ on evolution of low beyond Tuesday, but the trend will be for increasing heights in the Plains, thus warmer temperatures and a mainly dry forecast. && .AVIATION...
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(For the 12Z TAFS through 12Z Saturday morning) Issued at 603 AM CDT Fri May 19 2017 Latest surface obs across ern Neb this morning showing most sites IFR or less with pcpn activity lifting nwd over NE Neb. Expect low level moisture will remain in place over the region...thus no significant improvement anticipated through the fcst pd. Additional round of SHRA/ISOLD TS will likely expand in areal coverage this evening with activity continuing thru early Saturday morning.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...Flash Flood Watch through late tonight for NEZ091>093. IA...None. && $$ SHORT TERM...Dergan LONG TERM...Dergan AVIATION...DEE is the U.S. government's official web portal to all federal, state and local government web resources and services.