720 FXUS63 KGID 272026 AFDGID Area Forecast Discussion National Weather Service Hastings NE Issued by National Weather Service Bismarck ND 326 PM CDT Sat Apr 27 2024 .KEY MESSAGES... - Severe weather threat continues today, particularly counties along/south of the NE/KS border of greatest concern this time around where an Enhanced Risk (level 3 of 5) exists from SPC. - While all severe weather hazards are possible today-tonight within our coverage area (CWA), the main threat for very large hail and possible tornadoes should focus within the Enhanced Risk area in our south (a strong tornado even possible mainly in KS if a supercell tracks along the frontal zone). - Local areas of flooding/flash flooding can not be ruled out but opted against a formal Flood Watch (see reasoning below in separate HYDROLOGY section). - Although isolated/scattered storms will occur Sunday daytime, the track of the primary surface low pressure center (and attendant cold front) looks to skirt south and east of our CWA. As a result, we currently look to largely be spared a severe storm risk...although a few storms with up to around 1" size hail cannot be ruled out. - Following a break in thunderstorm chances mainly Sun night-Mon night, various low-confidence chances return especially Tues- Thurs as an overall-active pattern continues. - Temperature-wise: nothing unusual for late-April/early-May whatsoever, with highs most days somewhere in the 60s/70s and lows most nights in the 40s/50s. However, one of the chillier nights with more widespread mid-upper 30s is Sun night-Mon AM, and some frost cannot be ruled out, or even a sub-freezing reading here or there, especially north/west of the Tri Cities. && .DISCUSSION... Issued at 308 PM CDT Sat Apr 27 2024 Currently, surface low pressure was situated over the panhandle of Oklahoma with a warm front extending northeast into northeast KS/ southeast NE. A cool northeast surface flow was situated over the forecast area but with a warmer southerly flow approaching Mitchell, Osborne and Jewell counties in our far southeast CWA. Convection to the north of the warm front has lifted into far southern Mitchell and is approaching southeast portions of Osborne county. Late this afternoon and tonight the aforementioned warm front will try to lift northward this afternoon but may not make much progress as current convection over the southern CWA possibly pushes the warm front south a bit. There is growing evidence that convection lifting northward this afternoon will be more isolated or perhaps scattered in nature as it lifts into Nebraska and towards the I-80 corridor. A majority of the CAMS are not that robust with convection as it lifts into Nebraska. The strongest cells remain in Kansas, closer to the warm front. With that said, significant strong bulk shear remains over the entire CWA, and MU CAPE continues to inch northward into south central/southeast NE, keeping the threat of elevated strong to severe convection a possibility. As we go through the afternoon we may continue to pare down the pops a bit. For now they are a blend of our latest NBM pops with the consensus of short term guidance. If the warm front position does remain farther south, this may also limit the potential for tornadic storms, but again with the surface low remaining in the vicinity, the potential will remain, especially over our southeast Kansas counties and possibly into the southern tier counties of Nebraska. As was mentioned in the previous discussion there may be a bit of a lull between the the current round of convection lifting north into the forecast area, and another round later tonight as the surface and upper level lows both lift north and east into the Plains. However, there may not be a lull in some areas as convection also is rapidly developing over west central Kansas and will be lifting into our southern CWA shortly. It's possible we see convection lingering over Kansas and our southern NE counties into the evening, with another wave lifting northeast through a good portion of the CWA later tonight as the aforementioned upper low lifts into the local area increasing forcing for ascent throughout the CWA. Either way, it looks to be a busy afternoon and evening across the areas, and especially over Kansas this afternoon. SPC has just issued a severe thunderstorms watch that includes all of our Kansas counties through 9 PM this evening. Sunday the surface low tracks off to our east and the upper level low lifts northward just to our west. This should make for a cloudy and cool day with numerous showers and isolated to scattered thunderstorms through the morning and possibly into the afternoon, before tapering off Sunday night. Our far southeast counties will remain near but just outside of the marginal risk for severe storms. Finally by Sunday night we begin to clear out from southwest to northeast. Will need to monitor the western and northern counties for possible freezing temperatures. Currently, we do have a mention of frost and the latest NBM guidance is depicting some temperatures below freezing west and north of the Tri Cities. For the most part, the upcoming work week remains fairly active, although Monday may bring us a bit of a break in convection. By Tuesday, we see a broad upper level trough develop over the northwest U.S. into the northern Plains. An initial cold front moving through the central Plains on Tuesday may bring isolated to scattered thunderstorms to the area, but at this time the greatest instability and higher moisture remains south and east of the forecast area. In the Wednesday through Friday timeframe another upper level low tracks through the aforementioned mean upper level trough. With a broad southwest upper flow over the area isolated to scattered showers and and a few thunderstorms are possible on Wednesday, with better chances for more widespread showers and thunderstorms as another surface low develops in the lee of the Colorado Rockies and the upper level low tracks across the central/northern Rockies. This could bring us our next chance for strong to severe storms, especially over our Kansas counties. Then by late Thursday uncertainty increase in how the upper low evolves as we head into the weekend. Perhaps we have a dry Friday or it's possible we see showers and a few thunderstorms. Currently the NBM not really resolving this, leaving us with a broadbrush of slight chance to chance pops late in the work week and early next weekend. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1211 PM CDT Sat Apr 27 2024 Currently, a scattered to broken layer of CU/SC remains along the I- 80 corridor from Grand Island to Kearney with more widespread broken Cigs around KEAR. Another band of low VFR cloudiness over the southern portions of the CWA was working its way north. Eventually this afternoon we should see mainly Broken to Overcast Cigs, right around the MVFR/VFR threshold. As for precipitation chances, short term models want to bring a band of warm advection shower/tshower activity into the KEAR- KGRI corridor late afternoon/early evening. Differences remain in the intensity of this activity and coverage looks to be more isolated to scattered in nature at this time. For now will handle this with a VCTS. Later this evening as the strong upper level wave moves into the Central Plains, another round of thunderstorms is possible. In general, guidance supports a timeframe of late evening into the early overnight hours. For this will add showers with a TEMPO for Thunderstorms for a 4 hour period or so. Late tonight and through Sunday morning as the surface low remains southeast of the area, and the upper low lifts north just to our west, widespread IFR to possibly LIFR ceilings cover the area with a northerly surface flow of 10 to 25 knots at least through mid morning, and possibly through the entire 18Z TAF period. Can't rule out some occasional thunder continuing into the early morning hours but for now will limit it to the most likely period of stronger thunderstorms. && .HYDROLOGY... Issued at 537 AM CDT Sat Apr 27 2024 HYDROLOGY...Not much has changed Hydrologically speaking as well. The next paragraph is from the previous discussion but still holds: Fortunately from a flooding hazard perspective, the vast majority of our coverage area (CWA) picked up less than 0.50" of rain during the daytime-early evening Friday. As a result, for those various parts of our CWA that picked up anywhere from 2-5" of rain during the Thursday evening-Fri AM event, they will end up having roughly 24 hours (or more) of "drying time" before the next round(s) of storms moves in late this afternoon into tonight. As for the convection this afternoon and tonight we do see moisture and thus PWATS increasing, mostly south and east of the CWA but these will increase over the entire forecast areas by this evening and most notably over the southeast half of the CWA. This area of higher moisture transport/PWATs remains south and east of the I-80 corridor and north which received the most rainfall Thu evening into Friday morning. Later tonight, convection looks to track quickly northeast with the most likely scenario for local exceedence of FFG being strong convection training over the same area. Will certainly need to monitor tonight, but will hold off on a Flood Watch at this time. Also, WPC keeps their initial Day 1 Excessive Rainfall Outlook category as only Marginal for our CWA. Will continue to mention heavy rainfall in our Hazardous Weather Outlook (HWOGID) with localized flooding/flash flooding possible. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ DISCUSSION...TWH AVIATION...TWH HYDROLOGY...TWH