Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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454 FXUS63 KOAX 140359 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1059 PM CDT Sat Jul 13 2024 .KEY MESSAGES... - Dangerous heat is expected for much of the area this weekend into Monday, with heat index readings of 100 to 110+ degrees likely. Sunday and Monday will be the hottest days. - More widespread storm chances (20-40%) arrive Monday night and linger through Wednesday. && .DISCUSSION... Issued at 340 PM CDT Sat Jul 13 2024 A large ridge continues to spin high pressure over the western US and is extending the record breaking heat. (Vegas just averaged a high of 117 over the past week. Hottest 7 day period in it`s recorded history). Temperatures at 2 PM are near 90F with heat indices over 100 in about half of our locations. A heat advisory is in affect for the entirety of the area until 8 PM when the last of the heat indices will slip below 105F. The area will be headline free overnight as apparent temps slip into the upper 60s and low 70s. Urban areas may remain a bit warmer due to the concentration of asphalt, steel and glass. Still, expect most homes with no A/C to briefly cool down overnight. Again, dewpoints this afternoon have bested our forecast which was already above the 90th percentile of model solutions. Have boosted dewpoints for Sunday afternoon and Monday afternoon as well. Remember, there is typically a lag of a few days for bias corrected models to catch on to a trend... this time driven by corn`s climatological peak in evapotranspiration. Isotropic upglide is responsible for the possible convection in northeast Kansas / northwest Missouri overnight. As of now, I`ve got no showers in the forecast for nearby areas overnight tonight, but it won`t take much shift in the action for a few showers in far southeast Nebraska. Expect dewpoints to slip over the southern half of the forecast area overnight thanks to a nocturnal summer jet that has a significant westerly component to it. It`ll allow southeast Nebraska to get a short break from the air impacted by corn sweat. I don`t expect much mixing, so strongest winds should remain off the surface overnight. It`ll be rather pleasant after dark and meteorologically the best time to walk the dog. H5 northwest flow over the mid-Missouri River valley will become more westerly over the course of the next 48 hours as the West Coast ridge becomes less amplified and broader as it noses into the Corn Belt. The warmest temps will be in western Kansas and Nebraska, but a thermal axis will stretch from Denver through Council Bluffs, just south of the surface front. Guidance has brought temp forecasts down a degree or two over the past 36 hours and my forecast has reflected this. It will still be dangerously hot with high temps 1-2 degrees warmer than today. A heat advisory remains for most of the area. But areas from the Kansas / Missouri state lines north to Fremont, Omaha, and Pottawattamie County, Iowa will be under an excessive heat warning from noon Sunday through 8pm on Monday. We may fall just shy of excessive heat warning criteria with the slightly cooler forecast. But with minimum apparent temps slipping only into the mid-70s for much of that area, am glad to let that warning continue. It`ll be difficult to cool off without an A/C unit, especially in our most populous downtowns. Find a way to cool off and stay hydrated. Avoid extended time outdoors. Sunday should remain dry with a stout EML / warm layer at H7. Monday will still be hot, but temps will slip for areas north of I-80 where a "cold" front will have more time to impact temps. Triple digit temperatures and heat indices over 105 are forecast for areas along and south of I-80. Expect low to mid-90s north of the interstate. That slowly sinking front will give a good indication where 20-30% PoPs are possible. Late Sunday night`s LLJ may bring enough isotropic upglide for a few showers in far northwest corner of the forecast area and Monday afternoon may see more. Storms capable of 1" hail and damaging winds look possible but not likely Monday afternoon or evening (Pops max out at 30%). I`m looking forward to the weather of Tuesday and you probably should, too, with temps running 10-20 degrees cooler than the day prior. Northwesterly flow at H5 will keep both temps and dewpoints lower than this weekend. This flow will keep temps cooler for the rest of the week, but will also direct shortwaves overhead. Wednesday and next Saturday are currently saddled with the best chances of showers / storms ... but even then, odds suggest most will remain dry. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1052 PM CDT Sat Jul 13 2024 VFR conditions are expected to prevail throughout the forecast period. The main concern through the period will be LLWS. KOMA and KLNK will experience strong winds at 2000 feet, bringing LLWS in the 03 to 12Z timeframe. Winds will be quite variable in speed and direction throughout the forecast period. Calm and variable winds will be present overnight in northeast Nebraska (KOFK) with southwesterly winds at KOMA and KLNK. Gusts up to 16 kts will be possible at KLNK overnight. Winds will slowly pivot to southeasterly throughout the day Sunday. Gusty winds from a decaying thunderstorm could approach KOFK during the 12-14Z timeframe, yet confidence is low in this occurrence. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Heat Advisory from noon to 8 PM CDT Sunday for NEZ011-012- 015>018-030>034-042>045-050-065-078-088. Heat Advisory from noon to 8 PM CDT Monday for NEZ015-033-034- 042>045-050-065-078-088. Excessive Heat Warning from noon Sunday to 8 PM CDT Monday for NEZ051>053-066>068-089>093. IA...Heat Advisory from noon to 8 PM CDT Sunday for IAZ043-055-056. Heat Advisory from noon to 8 PM CDT Monday for IAZ043-055-056. Excessive Heat Warning from noon Sunday to 8 PM CDT Monday for IAZ069-079-080-090-091. && $$ DISCUSSION...Nicolaisen AVIATION...Wood