####018004165#### FXUS63 KARX 040413 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1113 PM CDT Fri May 3 2024 .KEY MESSAGES... - Showers and scattered storms are expected mainly Saturday. Rainfall amounts of up to a half of an inch from the showers or storms. - Active pattern develops next week with periodic showers and storms through much of next week. Timing of convection into region remains an issue and will have impacts on the severe potential across the forecast area. && .DISCUSSION... Issued at 226 PM CDT Fri May 3 2024 Today through Saturday: While quiet weather is in store for the rest of the day, guidance continues to support a shortwave moving through the area on Saturday. Accompanying this wave will be a 30 to 40kt 850mb jet that will help to increase the moisture transport. PWATs will increase into the 1 to 1.3 inch range. Recent guidance continues to show some instability moving further north, as shown by general consensus of 250 to 500J/kg of SBCAPE. The highest instability continues to be in southern Wisconsin. Despite this instability, it is not enough to promote any severe weather, even with the high amounts of shear, 30 to 50kts of 0-6km bulk shear. This means that thunderstorms will be possible as the band of precipitation moves through the morning and early afternoon on Saturday. Sunday into Monday Shortwave ridge builds into the Upper Great Lakes Region Sunday into Monday. Subsidence underneath ridge will allow for mainly dry weather across the forecast area both days. With light winds near the surface...clear skies and an inversion developing over the forecast area Saturday night/Sunday morning. There is the possibility of fog formation across parts of the area...mainly in low lying areas/river valleys. However...if northwest winds stay up enough...fog may not form. At this time...have left mention of fog out of the forecast. Warmer airmass advects into the region Sunday into Monday...as 925mb temperatures warm from around plus 10 degrees celsius Sunday to near plus 14 degrees celsius by 00z Tuesday. High temperatures will be mainly in the 60s Sunday and warming into the upper 60s to middle 70s Monday. Monday night through Friday Main forecast concerns from Monday night through Friday continues to be shower/storm chances through much of the forecast period. Upper level closed low slowly moves over the Northern Plains States and weakens during the forecast period. Latest ensembles/deterministic models continue to show differences in timing of the upper level closed low/impulses rotating around the closed upper level low into the Upper Mississippi River Valley. Confidence in timing of convection and any severe potential with the storms remains low. The latest GFS/ECMWF continue to indicate vertical motion/moisture convergence with the closed upper level low/impulses. This will produce periodic showers/storms through much of the forecast period...Monday night into Friday. Temperatures will remain near or slightly above normal with highs generally in the lower 60s to middle 70s through the forecast period. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1113 PM CDT Fri May 3 2024 VFR conditions look to continue through the overnight. Showers and perhaps a few thunderstorms will begin to move into the area towards the morning hours. Have maintained the previous forecasts trend with ceilings as guidance continues to indicate a period of MVFR. A few models suggest ceilings could lower to IFR for a time, especially at KRST, but confidence remains a bit lower so have opted to hold with MVFR and monitor trends/observations. Some reductions in visibility may be possible at times with heavier rainfall as well. Otherwise, light winds will begin to shift more northwest through the day. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...DTJ AVIATION...EMS ####018007585#### FXUS63 KGLD 040414 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 1014 PM MDT Fri May 3 2024 .KEY MESSAGES... - Fire weather concerns return Monday through Thursday for most of the Tri-State area, but favor along and south of I-70. - Thunderstorms, a few of which may become strong to possibly severe, will be possible Monday afternoon/evening. && .UPDATE... Issued at 1012 PM MDT Fri May 3 2024 The entire CWA has been cleared from earlier Severe Thunderstorm Watches. Most of the area is not seeing any precip at this time, and the remaining eastern zones seeing activity is seeing sub severe returns on radar. Still could see gusts 40-50 mph in the remnants as they exit, but severe wx is done for this night. Have added in Fog for all areas, along with patchy frost in the NW. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 130 PM MDT Fri May 3 2024 Not much has changed from previous thinking with two areas of concern for the remainder of the afternoon and this evening. Convective initiation has occurred in eastern Colorado near Las Animas. HRRR shows this activity expanding into northeast Colorado south of I-70 and northwest Kansas over the next few hours. Latest analysis and forecast of SBCAPE shows 1500-2000 j/kg available along with effective bulk shear values of 40-50 kts. Those parameters should be sufficient for a few severe thunderstorms capable of producing large hail, damaging winds and perhaps a tornado with any discrete supercell. Further north, initiation has also occurred along the cold front in the Nebraska panhandle. As the cold front surges south this evening, convection will increase rapidly into a line capable of producing damaging wind gusts. Given the same parameters above, a few embedded cells in the line will also be capable of producing large hail and a brief tornado. The front will exit the area by around 06z ending the severe threat, though a few showers and storms may linger past 06z in southern and eastern areas. Mean precipitation amounts for the event range from around a tenth to a quarter of an inch in Colorado, a quarter to a half inch west of Highway 83, and around a half inch east of Highway 83. The higher percentiles show locally up to 1 inch possible in just about the entire area, with up to about 1.5 inches in northeast corner (McCook, Oberlin, Norton) and southern areas (Tribune, Leoti). Winds will gradually diminish overnight with low temperatures ranging from the lower 30s in Colorado to the lower 40s in north central Kansas. Saturday will be mostly sunny and breezy with just a hint of shortwave ridging aloft ahead of weak shortwave in southeast Colorado. High temperatures will be in the lower 60s. Saturday night now looks dry with the shortwave staying south of the area. There will be some increase in clouds with low temperatures in the lower 40s. Models do hint at fog developing in western portions of the area late Saturday night into Sunday morning (along the Kansas and Colorado border area and westward). Southwest flow aloft continues on Sunday with embedded weak waves which may result in a few isolated showers and thunderstorms by Sunday afternoon. There is a very narrow corridor of weak instability forecast along the Kansas and Colorado border area with a 100-200 j/kg currently indicated. So, not expecting any severe storms should any develop. High temperatures will be in the upper 60s to lower 70s. Shower and thunderstorm chances increase going into Sunday night with height falls ahead of the approaching trough and nocturnal low level jet. MUCAPE increases overnight to 1500-2000 j/kg with shear values of 40-50kts. So may see elevated thunderstorms late with a risk for hail, but confidence is low at this time range. Low temperatures will be in the 50s. Main trough axis ejects out of the Rockies and across the plains with a negative tilt on Monday. Surface low will deepen in the Nebraska panhandle with the dry line trailing south into the forecast area. The dry line will be the focus for convective initiation in the afternoon and the models indicating the dry line will likely be in eastern areas at least for a few hours before moving east. Timing of initiation will be critical, but if it happens before the dry line moves out may see a short window for severe storms along/east of Highway 83. Instability and shear will be more than adequate for a risk of large hail, damaging winds and tornadoes. West of the dry line may see few wraparound high based showers, but no severe threat. However, afternoon relative humidity values will be dropping to near critical or critical values and wind speeds also appear to meet critical thresholds for fire weather concerns. Precipitation should be east of the area Monday night. High temperatures will range from the upper 60s in Colorado to the upper 70s in north central Kansas and lows Monday night in the upper 30s to lower 40s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Issued at 153 PM MDT Fri May 3 2024 Tuesday, an upper trough will be in place over the High Plains and Central High Plains. Models continue to show variations in the placement of a low pressure system ranging from Nebraska to the Dakotas. Kept winds where they are for now due to continued uncertainty on the location of the low, but wouldn't be surprised if later model runs start to bring up wind potential a bit. Zonal flow will be in place over northwestern Kansas and eastern Colorado through the day. Expected highs will range from the upper 60s in portions of Yuma and Kit Carson counties to the mid to upper 70s south of I-70. Wednesday, a disturbance will move across the Dakotas and Nebraska. We are currently forecast to stay dry through the daytime hours. Some cooler air will move in, with highs ranging from the mid to upper 60s in eastern Colorado to the upper 60s to low 70s in Kansas and Nebraska. Heading into the evening and overnight hours, there will be a 10-20% chance of a few showers and thunderstorms, mainly for areas along and west of the Colorado state line. Thursday, the disturbance will continue to move to the east, with low end chances (10-30%) of shower and thunderstorm activity. For the time being, areas west of a line from McCook to Tribune stand the best chance of receiving precipitation with this system. Expected temperatures will be in the 60s for highs and the 30s and 40s for lows. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 418 PM MDT Fri May 3 2024 For KGLD, the terminal is expected to see VCTS/TSRA through at least 05z Saturday, but may persist through 11z. 5-6sm in rain and VFR clouds attm. Winds, south 20-30kts through 02z then north 20-40kts. By 11z, north at 10-15kts, the veering east by 20z. LLWS 02z-05z Saturday 280@40kts. For KMCK, the terminal is expected to see VCTS/TSRA through at least 05z Saturday. Potential to persist through 12z. 5-6sm in rain and VFR clouds attm. Winds, southeast 20-30kts through 03z Saturday, then northerly 20-40kts. LLWS 01z-03z Saturday 260@60kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ UPDATE...JN SHORT TERM...024 LONG TERM...Wekesser AVIATION...JN