Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 220842 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 342 AM CDT FRI JUL 22 2016 .SHORT TERM...
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(today through Sunday) Issued at 342 AM CDT Fri Jul 22 2016 Heat and humidity continue to be the main story for the area into the weekend. 00Z upper air analysis indicated a 599 dm ridge from KDDC to KAMA. The analysis did indicate a number of shortwave troughs topping the ridge. The first was over eastern NEb/western IA and was responsible for for a good deal of mid-level clouds and even a few SHRA over western IA early this morning. Upstream another shortwave associated with some 10 m H5 height falls was over WY, and finally a stronger system with 30-40 m H5 height falls was moving into the PAC NW. The lead shortwave will slowly work east today, but some mid-level moisture, above the EML, will linger into the morning and possibly the afternoon. This may continue to lead to weak SHRA activity from the mid-level moisture field and will hold onto some pops into mid to late morning. Otherwise another hot and humid day is in store for the CWA with little change in the airmass from previous days. With similar mixing another day in the mid and upper 90s with heat index values well over 100 appears likely. The WY shortwave trough will move east today, and into the mid and upper MO River Valley tonight. The GFS/EC are consistent in focusing lower tropospheric WAA over the CWA tonight and although mid-level temperatures remain warm, we will likely see at least scattered convection develop associated with this pattern near or after midnight, with this activity lifting northeast into IA by Saturday morning. How much convection and any associated clouds lingering into Saturday morning creates just enough uncertainty in conditions for later in the day to extend the excessive heat warning, but given the current forecast this will likely be needed for at least part of the area in later forecasts. As the stronger PAC NW system moves into the northern Rockies, and eventually the northern Plains this will allow for a surface cold front to move southeast across the CWA. This front will approach the CWA by late Saturday afternoon. It appears the NAM over- amplifies the shortwave allowing for cooling of the EML, but we prefer the stronger capping from the EC/GFS with any convection developing to the northwest of the CWA and trying to move in on Saturday evening. We expect convection will have a hard time trying to move south through the CWA though on Saturday night with the warm mid-level temperatures, but will maintain some pops along the frontal boundary. This front will either stall over the far southern CWA on Sunday or just across the border into MO/KS. Highs will be a touch cooler on Sunday, but the south still will see heat index values over 100 likely. .LONG TERM...(Sunday night through Thursday) Issued at 342 AM CDT Fri Jul 22 2016 The extended period of the forecast is looking a bit cooler and more active as far as rain chances. The southern Plains upper level ridge will retrograde during this period allowing for lower heights and cooler temperatures for the CWA, along with periodic fronts and associated chances for convection. WAA atop the stalling frontal boundary may lead to the first chance at rain on Sunday night as models are in fair agreement depicting convection developing to the west and moving east/southeast along the boundary with the highest pops in the southern CWA. Additional shortwave troughs appear possible on Tuesday and Wednesday with a continued chance of showers and thunderstorms before potentially a dry period to end the extended as the front drops a bit farther south.
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&& .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1113 PM CDT Thu Jul 21 2016 VFR conditions will continue through the period as broad area of high pressure aloft remains anchored over the southern plains. && .OAX Watches/Warnings/Advisories...
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NE...Excessive Heat Warning until 8 PM CDT this evening for NEZ011- 012-015>018-030>034-042>045-050>053-065>068-078-088>093. IA...Excessive Heat Warning until 8 PM CDT this evening for IAZ043- 055-056-069-079-080-090-091.
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&& $$ SHORT TERM...Boustead LONG TERM...Boustead AVIATION...Fobert

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