Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 232356 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 656 PM CDT Sun Jul 23 2017 .SHORT TERM...(Tonight through Monday Night) Issued at 321 PM CDT Sun Jul 23 2017 As advertised, a somewhat cooler and drier airmass continues to build south across the region today with temperatures ranging from the middle 80s in northeast Nebraska to the lower 90s in far southern reaches of the forecast area. Dewpoints have also dropped considerably, with comfortable 55-63 degree dewpoints expected to be common across the entire area by mid evening. Surface high pressure will build southeast overnight with the surface ridge axis extending down the Missouri valley by sunrise on Monday. This should promote light or calm winds and effective radiational cooling in the presence of remnant near-surface moisture. These ingredients suggest at least the potential for patchy fog especially in low areas along the Missouri Valley and eastward into western Iowa. At this time, confidence in fog development is low but if/where it does develop, some patchy dense fog is possible. On Monday, surface winds turn back out of the southeast with some warm advection gradually nosing into the area. All-in-all it will be a pleasant day especially when compared to the past week, with near-normal temperatures expected. There is a vorticity maximum currently very evident in WV imagery over SW Montana which will slowly but surely track across southern South Dakota. This may provide adequate lift to initiate convection late Monday into Monday night mainly near the NE/SD border. Low levels will be very dry but model soundings (and WV imagery) suggest mid-level moisture associated with the system may support uncapped convective parcels over far northern NE and perhaps into west central IA. Severe potential is low as the elevated instability and effective shear are not particularly impressive. Warmer weather is expected Tuesday into Wednesday as south winds increase and a strong short wave trough tracks across southern Canada. This trough will push a cold front toward northern parts of the forecast area by early Wednesday morning while reinforcing short wave energy gradually pushes the front through the whole CWA by Thursday. Should see quite a bit of convergence along this slow moving frontal boundary while the interaction with the modified monsoonal moisture plume and weak periods of mid/upper level energy to produce a few rounds of thunderstorms. Have thus gone with relatively high precip chances for the general Wednesday time frame with the exception that the activity will be scattered in nature and a few locations may still very well go untouched by precipitation. In the end though, the slow movement of the system and availability of multiple forcing mechanisms suggest that higher end Pops are reasonable. Temperatures behind this system may actually fall below normal for multiple days as a northwest to nearly meridional flow pattern is set to dominate the local forecast area. .LONG TERM...(Tuesday through Sunday) Issued at 321 PM CDT Sun Jul 23 2017 Warmer weather is expected Tuesday into Wednesday as south winds increase and a strong short wave trough tracks across southern Canada. This trough will push a cold front toward northern parts of the forecast area by early Wednesday morning while reinforcing short wave energy gradually pushes the front through the whole CWA by Thursday. Should see quite a bit of convergence along this slow moving frontal boundary while the interaction with the modified monsoonal moisture plume and weak periods of mid/upper level energy to produce a few rounds of thunderstorms. Have thus gone with relatively high precip chances for the general Wednesday time frame with the exception that the activity will be scattered in nature and a few locations may still very well go untouched by precipitation. In the end though, the slow movement of the system and availability of multiple forcing mechanisms suggest that higher end Pops are reasonable. Temperatures behind this system may actually fall below normal for multiple days as a northwest to nearly meridional flow pattern is set to dominate the local forecast area. && .AVIATION...
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(For the 00Z TAFS through 00Z Monday evening) Issued at 654 PM CDT Sun Jul 23 2017 VFR conditions through the period. There may be some patchy MVFR fog in the area 10-13z at KOMA.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Barjenbruch LONG TERM...Barjenbruch AVIATION...DeWald

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