840 FXUS63 KGID 260011 AFDGID AREA FORECAST DISCUSSION National Weather Service Hastings NE 711 PM CDT Mon Oct 25 2021 .UPDATE... Issued at 700 PM CDT Mon Oct 25 2021 Made significant changes earlier in the shift to sky cover overnight and into Tue AM, and observational data and latest short term guidance still supports those changes. Status has held firm for most of the CWA all day, and with continued SE flow and additional stratus noted upstream over E KS/W MO, see little evidence to support idea that we'll get rid of the stratus overnight. There is a break between the two blocks of stratus from Beloit/KCNK towards KSLN, which the HRRR depicts quite well. Agree with the HRRR that this area should fill in as low level SErly flow incr overnight. The biggest remaining question I have is potential for fog and/or drizzle late tonight into Tue AM. Several pieces of model guidance (both MOS and deterministic) dev some sort of visibility reduction over various portions of CWA, but agreement on timing and location is not great, and breezy SE winds and lack of stronger moisture surge tend to argue against this potential. However, overall moisture depth should incr with time, and broad/persistent lift in WAA regime along with turbulent BL beneath stout inversion could be enough to generate areas of drizzle...which would undoubtedly come with at least modest visibility restrictions towards 3-5sm, perhaps lower. Thus, have added patchy fog wording for much of our Neb. zones as a start, and will evaluate new 00Z guidance to help make determination on drizzle later this eve. Regardless of drizzle potential, tend to favor RAP/HRRR/NAM solutions that keep stratus around for much of the area through at least midday Tue...and just like today, there's a chance it could hang around most of the aftn and again affect high temps. && .DISCUSSION...(This evening through Monday) Issued at 329 PM CDT Mon Oct 25 2021 Low stratus continues for nearly the entire forecast area early this afternoon. A small corner of the northeast has broke out. Temperatures have struggled to move this afternoon. There are many concerns for this forecast. Cloud Cover, temperatures, winds, chances for thunderstorms and severe weather are just a few. The first are the clouds for tonight. When we have not cleared out at this point in the afternoon, there is concern that they will linger all night long. Have went with a slower clearing during the evening, but expect that they will return toward sunrise. Will have to watch to see what the clouds do tonight. A surface high moves to the east and the pressure gradient tightens tonight. Winds at 850mb increase to 40 to 50 knots. Expect winds to start to increase during the night tonight. That should keep any fog from forming at the edges of the stratus field, but it could also bring some chances for drizzle to the area. The NAM has an area of low QPF amounts spreading into the area late tonight and continues to move through the area during the day Tuesday. Should the stratus linger, there could be some drizzle out of it. The clouds will also have an impact on the temperatures during the day Tuesday. Have lowered highs some and will need to watch them, especially if there are more clouds. Tuesday night an upper level low approaches the area and a surface low and cold front move through the area. In the vicinity of the front there will be a chance for some thunderstorms. There is a fairly narrow band of decent CAPE for this time of year that moves into the area during the evening. The best chance for thunderstorms will be late in the evening and into the overnight hours. Expect wind to be the primary threat, but with cooler temperatures and lower freezing level there could still be some hail potential. Due to the linear nature of the expected storms, there could be an isolated tornado or two. The front finally exits the eastern part of the forecast area on Wednesday morning. There could be at least a little thunder in the eastern part of the forecast area during the day on Wednesday. The precipitation should end from west to east during the afternoon. Temperatures will be quite a bit cooler on Wednesday with highs only in the 50s due to cloud cover and behind the front. In addition, there will be a strong northwest wind. Winds aloft continue to be 40 to 50 knots and with the showers and thunderstorms some of that wind could mix down toward the surface. By Thursday, when the sun has a better chance of coming out and there is better mixing, the winds could be even stronger, especially in the morning. By afternoon there is a surface high that starts to build in, but winds will be fairly strong through the afternoon and should die off around sunset. Friday and Saturday will have a little warming trend. There is an upper level ridge that moves through, some warm advection and sunshine. A cold front moves through the area Saturday night and temperatures will be cooler Sunday and Monday. Forecast highs are in the 40s and lows are below freezing for most areas Sunday night. This could bring an end to the growing season. Cooler temperatures are expected Monday night, so if Sunday night is not enough, Monday night will do it. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 650 PM CDT Mon Oct 25 2021 Significant weather: Prolonged IFR to LIFR CIGs, perhaps MVFR VSBYs, strong SE winds. First 6 Hours: IFR to LIFR. Made significant changes this TAF cycle as we have been unable to shake these low clds. It now appears probable both sites will maintain IFR CIGs, and probably even lower to LIFR within next few hrs. In fact, have already seen a lowering trend last hr or two and with loss of insolation expect this trend to continue. Wind will remain breezy out of the SE around 10-15kt, with gusts around 20kt. Rest of the Period: LIFR to IFR through Tue AM, possible(?) improvement Tue aftn. LIFR or barely IFR CIGs are likely after midnight through much of the morning Tue per latest short term model guidance/trends. May even approach airport minimums (200ft), at times, esp. at EAR. VSBYs are more in question as several models develop MVFR to IFR BR/FG, but breezy SE winds and lack of more discernable surge of low level moisture argue against it. Have trended the forecast towards at least some VSBY reduction, but think this will be more of mist/drizzle and not true FG, so kept MVFR attm. Given what happened today (Mon), improvement will probably be very slow/minor Tue AM. Confidence on stratus trends Tue aftn is low as some models completely mix the stratus out, whereas others keep us locked in. Will trend towards improvement 19-21Z, but again, this is low confidence. Finally, winds will be pretty high throughout the day out of the SE...susatained 16-21kt, with gusts around 30kt, perhaps higher if skies clear out. Removed LLWS given elevated sfc winds and fact that core of strongest low level flow looks to remain above 2000ft. Confidence: Medium to high thru Tue AM, low Tue PM. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Thies DISCUSSION...JCB AVIATION...Thies