Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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972 FXUS63 KOAX 071133 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 633 AM CDT Tue May 7 2024 .KEY MESSAGES... - Marginal risk of severe thunderstorms Wednesday afternoon and evening northeast Nebraska and western Iowa - Light showers and a few rumbles of thunder linger through the end of the work week, with drier conditions and highs in the 70s returning for the weekend. && .DISCUSSION... Issued at 408 AM CDT Tue May 7 2024 Today: Complex of thunderstorms that brought severe weather to the area has moved well east of the forecast area. Surface cold front and pre-frontal trough located across western periphery of forecast area. Low level moist advection continues. Combined with wet soils from Tuesday night rains, there is a small window for for development early this morning given clearing skies across the area. Will monitor over the next few hours, but left mention of any patchy fog out of the forecast for now. A quiet day weatherwise is expected today. A broad H5 trough will be in place across the northern plains, anchored by a closed H5 low over the Dakotas. Weak disturbances rotating around the trough, aided by diabatic heating will aid in the development of isolated to scattered sprinkles/showers this afternoon into early evening. Seasonal temperatures are expected. Tonight: Aforementioned H5 low and trough syncs with North Atlantic vortex and digs south-southeast overnight as upper level jet rotates around base of vortex. This will allow for isentropic ascent and sharpening midlevel flow. Expect scattered showers/isolated thunderstorms to develop, though dry low level may limit precipitation from reaching the ground. Wednesday: Upper low begins to eject northeastward during the day on Wednesday, with a broad upper level jet of 50-70 knots persisting through the day, resulting in bulk shear 35-45kts. Expect mid- level lapse rates to increase, especially across northeast Nebraska and northwest Iowa as cold-core from upper low moves across the area. At the surface, an inverted trough will move across the forecast area, advecting a narrow band of greater thetae into eastern Nebraska and western Iowa. A few of the CAMS develop a narrow ribbon of 1000-1500 J/kg CAPE. In tandem, expected thunderstorm develop during the afternoon, with possibility of isolated severe storms. HREF hinting at potential for a few rotating storms. Increased clouds and precipitation chances will keep high temperatures a few degrees cooler, especially northeast Nebraska and northwest Iowa. Thursday-Friday: Upper low transitions to open wave as it completes syncing with North Atlantic trough. Cyclonic flow will remain in place across the area, continuing chances for showers and isolated thunderstorms on Thursday. Low level cold advection will keep temperatures in the 60s. A more pronounced shortwave feature drops southward from northern plains on Friday afternoon. Downslope low level flow will help bump temperatures back into the 70s for highs. Afternoon shower and thunderstorm development again will be possible, possibly a little more vigorous as passage of shortwave will occur during peak diabatic heating. Saturday Onward: Upper level ridging builds across the area, bringing an end to precipitation chances. Seasonal temperatures are expected. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 630 AM CDT Tue May 7 2024 Southerly to southwesterly winds are in place this morning with the expectation that winds increase between 15-17z depending on the site with gusts to 25 kts. VFR conditions are expected through the period, with the gusty winds dropping off at 00z this evening, with no fog currently expected overnight. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Fortin AVIATION...Petersen