Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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648 FXUS63 KOAX 091136 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 636 AM CDT Thu May 9 2024 .KEY MESSAGES... - Scattered showers and isolated thunderstorms are expected across the region today bringing a 20 to 40 percent chance of rain at any given location. No severe weather is expected. - Several rounds of showers and thunderstorms are forecast Sunday through Wednesday. Current indications for the greatest precipitation chances of 50-60%, are expected Sunday night and Monday afternoon. No severe weather is expected. - Slightly above normal high temperatures in the middle 70s to lower 80s this weekend, and again the middle of next week. && .DISCUSSION... Issued at 340 AM CDT Thu May 9 2024 Today and Tonight... An elongated upper level trough extends from essentially from the North Atlantic to the western U.S. The western U.S. anchoring upper level low disconnects during the day today, leaving a closed upper low over the intermountain region of the West. The forecast area will remain under the influence of the cyclonic shear side of the trough today through late evening. Convergent moist, isentropic flow will persist At the surface a surface trough will move southward across the area. The combined effect will be scattered (10-30% coverage) showers. Diabatic effects will allow for isolated thunderstorms during the late afternoon and early evening. Precipitation totals of only a few hundredths, with isolated amounts of one or two tenths where thunderstorms occur, are expected. Temperatures today will be slightly cooler (60s) due to low level cold advection and evaporative cooling. Overnight temperatures generally will be in the 40s. Friday and Saturday... Generally dry conditions are expected, though a shortwave dropping southward from Manitoba/Ontario into the Ohio Valley Friday afternoon may bring portions of western Iowa and extreme eastern Nebraska isolated showers and thunderstorms. Most areas will remain dry. West to northwest winds 15 to 20 mph will gusts 20 to perhaps 30 mph on Friday. A nice day is expected for Saturday with sunshine, light winds and temperatures in the upper 70s. Saturday Night through Wednesday... The closed low over the intermountain region moves slowly east southeast across the central and southern plains. Sharpening the wind field. Large scale isentropic ascent ahead of the system will draw moisture northward from southern Texas across the southern High Plains with models indicating saturation H8-H7 by Saturday night. The attendant surface system will be Oklahoma and Texas, with an inverted trough extending into the northern plains. As forcing mainly will be from the mid-levels, expect any storms that develop to be elevated. The better shear and instability will reside across the southern plains, thus expect only general thunderstorms. The wave moves into the southeast U.S. by Tuesday, but is followed quickly by another shortwave diving southeast across the plains Tuesday night into Wednesday. Mass field response appears limited, as low level moisture return appears questionable. Though cooling mid-levels appear enough to decrease lapse rates. As such, better chances for stronger storms by Wednesday. High temperatures will remain above normal through the period, with highs near 80 by Tuesday. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 630 AM CDT Thu May 9 2024 VFR conditions start out the period with northwesterly winds in place at 10 kts or less. Main concern of the forecast is the potential for MVFR ceilings developing mid-to-late morning at FL015 to FL030 as clouds develop and move in from the north, with showers becoming a possibility during the afternoon (but generally less than a 30% chance). As of right now, it looks like a period of broken clouds will be in place at KOMA but have kept the time limited until we see it beginning to develop. Gusts of around 20 kts will develop this afternoon as well, but will quickly drop off by the evening hours. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Fortin AVIATION...Petersen