Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 131947 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 247 PM CDT Tue Mar 13 2018 .SHORT TERM...
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(Tonight through Friday) Issued at 245 PM CDT Tue Mar 13 2018 Fire weather concerns develop on Wednesday, and slightly less on Thursday, then focus shifts to a wide mix of rain and wintry precip Thursday night into Friday with the potential for minor icing and snow accumulations in some areas. High pressure and clear skies today, with high pressure shifting east overnight. Winds will diminish and may even become light in some areas overnight, before becoming southwest by daybreak Wednesday, with temps dropping into the lower 20s. Breezy southwest winds increase to 10 to 20 mph through the day Wednesday, which should help tap into warmer temperatures aloft, helping to push surface temps into the 60s for many areas, possibly making a run for 70 in parts of eastern NE. This does lead to increased fire danger which will be detailed later in this discussion. Lee cyclogenesis develops Wednesday night as a weak front settles southward through the area, in response to the closed low pushing into the Rockies. This sets up a tighter temperature gradient across the forecast area for Thursday, with highs in the upper 40s to lower 50s north of the front, but still in the mid 60s near the KS border. Increased surface dewpoints help keep minimum humidities in the 35 to 45 percent range, which should help somewhat mitigate fire weather concerns. Challenging weather develops Thursday night into Friday as the weather system begins to move out of the Rockies. We are fortunately seeing much better model agreement today than the previous several days. Unfortunately, due to substantial warm air advection aloft around a very strong low pressure system, this leads to precipitation type issues in our forecast area, ranging from just rain along our southern areas, to a wintry mix of freezing rain, sleet and snow as you transition north toward the SD border. Have increased Pops into the 80-90% range through Friday, which is a substantial increase from previous forecasts. The wintry mix will occur along/north of a line from about David City, NE to Clarinda, IA. Snow amounts of 1-3" could occur in northeast NE. Minor icing of 0.02 to 0.15 could also accompany the wintry mix Friday morning. Some of this will be mitigated by warming temperatures through Friday afternoon, which should help switch over precip to mostly rain, and should also help with any slick roads that develop earlier in the day. .LONG TERM...(Friday night through Tuesday) Issued at 245 PM CDT Tue Mar 13 2018 The weather system begins to transition out of the area Friday night into early Saturday morning, but again, should end as a messy transition of rain, changing back to snow, or possible freezing rain or drizzle as we lose the deep moisture toward the end of the event. Saturday afternoon and night should be dry, but another strong weather system moves out of the Rockies Sunday through Monday which brings us another chance of rain and possibly accumulating snow mostly along/north of I80. Winter isn`t over yet.
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&& .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1228 PM CDT Tue Mar 13 2018 VFR conditions will continue across the area through the forecast period. High pressure from the eastern Dakotas into eastern Nebraska at 17Z will drift southeast towards the lower Mississippi Valley through tonight. After 12Z southwest to west winds will increase as surface gradient tightens. && .FIRE WEATHER...
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Issued at 245 PM CDT Tue Mar 13 2018 Afternoon temps rise into the 60s on Wednesday, and while dewpoints will be slowly increasing, minimum afternoon humidities are forecast to drop into the lower 20 percent range across southeast NE and southwest IA, and down to 30 to 40 percent elsewhere. Wind gusts could approach 20 to 25 mph at times. This will push rangeland fire danger (RFD) indicies into the very high category for most areas, but grassland fire danger indices (GFDI) only get to about 15 to 21, well below a critical threshold for red flag conditions. Thus, will continue to highlight very high grass fire danger in our hazardous weather outlook, but believe we will remain critical thresholds for red flag warning (RFW) criteria.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...DeWald LONG TERM...DeWald AVIATION...Fobert FIRE WEATHER...DeWald is the U.S. government's official web portal to all federal, state and local government web resources and services.