Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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729 FXUS63 KOAX 232344 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 644 PM CDT Sat Sep 23 2017 .SHORT TERM...(Tonight through Tuesday) Issued at 255 PM CDT Sat Sep 23 2017 The chance for showers and thunderstorms, frontal timing and the marginal risk for severe storms are the main forecast problems. Pattern remains similar to yesterday, with a mid level trough over the Rockies and a ridge from TX to the Great Lakes. 300 mb winds were strongest (90 knots plus) from AZ into WY, western ND and then into southern Manitoba. 500 mb height falls were strongest in AZ with around 50 meter falls noted at 12Z. 700 mb thermal ridge still extended from west TX into western KS but then was a little farther east today in MN, compared to the Dakotas yesterday. Moist plume in the lower and mid troposphere was still in place along and ahead of the nearly stationary front. Surface analysis showed the front from MN back southwest into eastern CO. Showers that develop from the ACCAS field this morning lifted north through early afternoon, but were not of much consequence. A few spotty radar echoes continued from south central into northeast NE at mid afternoon. Will keep some POPs along and northwest of a line from about Seward to West Point and Pender into early evening, but then confine chances mainly to just northeast NE overnight. Any storms in northeast NE could have some hail and wind. Lows tonight should be mainly 65 to 70, except in the lower to mid 60s northwest of the front, northwest of a line from about Albion to Hartington. The front may even lift back a little more the northwest by sunrise. On Sunday, there should again be a small risk for severe storms. High temperatures may be just a bit cooler than today, mainly in the upper 80s to around 90, except mid 70s to mid 80s in northeast NE. Some 12Z model guidance brings the front eastward during the day, with the NAM being the most aggressive. That model seemed to aggressive. Most of the precipitation should be along and behind the front. Still looks like potential for locally heavy rain, especially northwest of Lincoln and Omaha. PW values should increase Sunday night and reach 1.50 to 1.90 inches across most of the area by 12Z Monday, which remain in place then the rest of the day. Lift may be somewhat enhanced by upper tropospheric divergence, associated with the right entrance region of a jetstreak that is expected to curve anticyclonically from the western Dakota into western Ontario. Location of the front will be critical for highs Monday, and right now have highs ranging from upper 50s in our northwest counties to around 80 near the MO border. Generally look for highs in the upper 50s to mid 60s behind the front. Will keep precipitation chances mainly 50 to 75 percent for most of the area Monday. Things continue to push southeast Tuesday, with POPs decreasing from northwest to southeast during the day. Highs should vary from the lower 60s to near 70, with north or northwest winds. .LONG TERM...(Tuesday night through Saturday) Issued at 255 PM CDT Sat Sep 23 2017 Precipitation should be pushing southeast out of the area by early Tuesday evening based on most model guidance, so the long term forecast from mid week through Saturday looks mainly dry. Temperatures will be at or cooler than normal, with most highs from 65 to 75, and lows in the 40s to lower 50s. Mid level flow will be a lot less meridional in the central part of the Plains compared to earlier. A ridge will develop from the northwest US into western Canada, a trough should extend from eastern Canada down toward the Great Lakes and there will be a weak closed low in the Four Corners region by Thursday. && .AVIATION...
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(For the 00Z TAFS through 00Z Sunday evening) Issued at 638 PM CDT Sat Sep 23 2017 VFR conditions are forecast for most of the TAF period at all eastern Nebraska TAF sites. Scattered thunderstorms developing along a cold front in central Nebraska will remain west of sites overnight, but will begin to approach KOFK by around 18Z or so. Mostly likely time for storms there is after 20Z. There is a small chance storm could develop ahead of main line and affect KLNK or KOMA after 20Z, but low confidence in occurrence precludes mention in this TAF cycle. Otherwise southerly winds gusting to 25kt will subside somewhat overnight then increase again Sunday morning. Low level wind shear is likely all night at KOFK when southerly low level jet kicks in near 40kt at FL020.
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&& .CLIMATE... Temperature records for Sat Sep 23 are: Warm MaxWarm Min Omaha 96 (1892) 72 (1892) Lincoln 97 (1921) 72 (1930, 1892) Norfolk 92 (1921) 69 (1958, 1937) && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...Dergan CLIMATE...

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