604 FXUS63 KGID 212052 AFDGID AREA FORECAST DISCUSSION National Weather Service Hastings NE 352 PM CDT Sat Aug 21 2021 .DISCUSSION...(This evening through Saturday) Issued at 313 PM CDT Sat Aug 21 2021 Overview... Overall it will be warmer and wetter than normal period as we end the weekend and work our way through next week. Normal highs currently range from the mid 80s in the Tri-Cities to around 90 over north central Kansas and we should be at least that warm and likely a bit warmer than that on most days. We will also have a surface frontal boundary that will be moving back and forth in the region with some upper level shortwaves passing through as well bringing several chances of thunderstorms to the area. This Evening Into Tonight... The great weather will continue into this evening with temperatures in the 70s to lower 80s across the forecast area. We saw just a few sprinkles northwest of the Tri-Cities earlier this afternoon and those have largely ended although we can not completely rule out another sprinkle or two mainly northwest of the Tri-Cities through early evening. There will also be a chance for a few additional sprinkles or light rain showers late tonight, primarily as we get close to dawn again west and north of the Tri-Cities. This appears to be more of an isolated trace type of event as we see warm air advection increasing overnight. Sunday... There are a couple of big story lines here. First, we expect the wind to become a bit breezy out of the south ahead of the next upper trough, which will allow for increasing low level moisture and warmer temperatures. Highs on Sunday will be back into the upper 80s across most of southern Nebraska with 90s over north central Kansas. Second, although most of the upper level energy with the trough will be well north of us across the Dakotas, the best moisture will be over our area and there should be enough upper level support to kick off at least several strong to severe thunderstorms by late afternoon/early evening. Deep layer shear is high at around 40 kts and Surface Based CAPE values will be high as well at over 3000 J/KG according to the 18Z NAM. Most models also seem to be generating at least scattered thunderstorms across southern Nebraska by Sunday afternoon. At this time, it appears that the threat for severe thunderstorms is increasing for late Sunday. Severe hail and wind damage are the most likely and obvious threats with the supercells that develop. However, can not rule out at least some threat for an isolated tornado or two, if the sfc winds can back a bit more to the southeast ahead of developing storms, the low level wind shear remains a bit marginal for tornadoes, but there is at least some chance and will need to keep an eye on this one. Finally, heat index values by Sunday afternoon could be around 100 degrees over north central Kansas so will need to keep an eye on the heat and take precautions if you are outside for long periods of time in the sunshine. Monday... This should be another warm day, likely around 90 or higher for most areas. Therefore, heat index values will again be a concern around 100 in some southern zones. Thunderstorm chances are more uncertain, but there is at least a hint in a few models that we could see enough of a minor shortwave that with afternoon heating could pop off a few isolated thunderstorms by late afternoon/evening, mainly Nebraska zones. Tuesday through Saturday... This will remain a warm period although maybe cooling off a bit by Saturday. The overall upper pattern should not change much with an upper trough across the northwester United States into north central areas and a big upper level ridge across the southern plains. We will be in a bit of a battle zone between these two areas with some weak shortwaves coming through and a frontal boundary that should mainly stay north of us, but could sag south into our forecast area at times brining us some off and on chances for thunderstorms through the period. Northern areas will be most favored for precipitation during the extended period. && .AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Sunday) Issued at 1256 PM CDT Sat Aug 21 2021 The north wind early this afternoon will remain light and gradually swing around to southeasterly by early this evening. VFR conditions will continue throughout the TAF valid period. There is a small chance for thunderstorms late tonight through Sunday morning and then increasing chances for thunderstorms just beyond the end of the TAF valid period Sunday afternoon. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Wesely AVIATION...Wesely