Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 252329 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 629 PM CDT Thu May 25 2017 .SHORT TERM...(Tonight through Sunday) Issued at 245 PM CDT Thu May 25 2017 The primary forecast concerns are precipitation chances Tonight, then from Friday night through Saturday. Impressive mid tropospheric closed low (535 dm at 500 mb) was over southern Saskatchewan this morning. That feature should track northeast tonight, then wobble southeast toward Lake Superior by Sunday evening. 12 hour height falls of 50-100 meters were noted on the east side of the low, and also extended southwest toward California. Surface analysis at 19z showed a cold front across the Dakotas that extended down into central Nebraska and then back into eastern Colorado. Some showers have been occurring over parts of the local area, and may continue into the evening. Highest chances though are later tonight, when storms may roll in from the west. Combination of several weak features, including that cold front pushing through, will result in small chances for showers and thunderstorms overnight. For now, expect that it will be dry on Friday from mid morning through the evening. Look for lows tonight to be mainly in the 50s. Highs Friday should be mainly upper 70s and lower 80s, with some mid 70s possible in the far northwest part of the forecast area. Models are in pretty good agreement that showers and storms will develop to our west Friday evening, and then move east. Model timing is a little variable but will keep some low POPs going Friday night in parts of eastern Nebraska, but keep western Iowa and the far eastern fringes of Nebraska dry. Increased POPs a bit from the previous forecast for Saturday, especially through mid afternoon. Strongest large scale forcing for ascent are during the day Saturday. The 12z GFS and NAM are similar with timing, but the ECMWF and Canadian models are about 3-6 hours slower. Kept a low POP going into the evening, but based on current expected timing, it would be mainly out of our area. Clouds and precipitation should keep highs mainly 65 to 75. On Sunday, we will have a northwest breeze, but deeper mixing, so look for highs in the lower and mid 70s north to mid/upper 70s south. .LONG TERM...(Sunday night through Thursday) Issued at 245 PM CDT Thu May 25 2017 Closed low at 500 mb will initially be around or north of Lake Superior, with a ridge from the far western CONUS up into the Yukon and Northwest Territories. The result will be cool-ish northwest flow that should decrease as the pattern deamplifies and heights rise over the Central Plains. Have kept rain chances below 15 percent (starting late Saturday night) through Tuesday evening. Then we have chances mainly 20 to 30 percent from Tuesday night into Thursday. Models do differ though on which 6 hour periods have the best chances though. Highs should be mainly in the 70s, with lows in the upper 40s to mid 50s. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 619 PM CDT Thu May 25 2017 Conditions are generally expected to remain VFR through the period, however a few showers and thunderstorms could impact the TAF sites between 06Z and 12Z. The best chance for precipitation appears to be at KLNK and KOMA at this time. A couple hours of MVFR cigs coincident with the showers and thunderstorms can`t be entirely ruled out. Otherwise, southerly winds will become light and variable tonight, before swinging around to the north Friday morning. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...KG

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