Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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615 FXUS63 KABR 010128 AAB AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 828 PM CDT Sun Jun 30 2024 .KEY MESSAGES... - Winds out of the southeast gusting 30 to near 45 mph to expand to eastern SD/west central MN Monday while shifting out of the south and diminishing slightly. - There is a Marginal Risk (level 1 out of 5) of severe weather for around daybreak Monday mainly west of the Missouri River. The main threats will be large hail and strong wind gusts. - There is a Slight Risk (level 2 out of 5) for severe weather from mid afternoon Monday through Monday evening. At this point all severe weather threats are possible, including damaging winds, large hail, and even a tornado. The highest risk for a tornado will be over central SD. - The active weather pattern of showers and thunderstorms persists through the workweek. && .UPDATE... Issued at 828 PM CDT Sun Jun 30 2024 No changes planned to the tonight period forecast. UPDATE Issued at 624 PM CDT Sun Jun 30 2024 See below for an aviation forecast discussion for the 00Z TAFs. && .SHORT TERM /THIS EVENING THROUGH MONDAY NIGHT/... Issued at 210 PM CDT Sun Jun 30 2024 Winds will remain elevated as we move into Monday. Winds gusting 30- 35kts have been common west of the MO River, with a few higher values. The 2 to 3mb pressure falls in 6 hours due to the tight pressure gradient between the surface high over eastern MN/WI and low across WY will continue to spread east this evening. While winds will relax around 5kts, they will remain gusty through Monday. The low across WY will push into the western Dakotas early Monday morning. Storms over western ND overnight may clip our western, but mainly far northwestern counties 09-13Z Monday. While the main threat for strong to severe storms in the form of hail around 1" in diameter or winds around 60mph will be across far western ND, there is still a Marginal Risk (level 1 out of 5) of severe weather for counties mainly west of the MO River. Low level moisture will steadily increase during the daytime hours Monday, with relative humidity values staying at or above 60 percent during the day Monday. The 12Z runs of the NSSL WRF and NAM Nest have been a little more robust with the showers and a few thunderstorms developing over our eastern SD counties and remaining through much of the daytime hours. We have steadily increasing chances of precipitation (increasing from 20 to 70 percent) through the day. There are differences in when thunderstorms will develop or move over central SD Monday. The latest HRRR and and a couple of the FV3 runs indicate the potential as early as 21Z, others hold off until late afternoon with the storms developing over eastern WY/Black Hills of SD sliding into our western counties around 00Z. Much of this could be a result of the warmer air aloft capping some of the convection. The NAM is near 14C over central SD, while the HRRR is closer to 11C (weaker capping). There is plenty of room for change in this period, so we will continue to highlight that people be prepared for strong to severe storms as early as mid afternoon with golf ball sized hail and winds over 60-70mph, along with a tornado threat over central SD (2% tor off the latest SPC convective outlook). CAPE values peak across central SD 15Z Monday to 00Z Tuesday, with 0-3km computed cape values of 1500 to around 2000 J/kg, diminishing significantly after 00Z. A similar trend is noted with shear and lapse rates, diminishing as storms move east. Winds will diminish to less than 15kts Monday night as the surface trough tracks east and resides either near the SD/MN border or all into MN by 12Z Tuesday. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 210 PM CDT Sun Jun 30 2024 A passing upper level long wave trough, cold air advection and steep low level lapse rates may result in daytime heating showers and thunderstorms Thursday afternoon. Expect anything that can get going will be isolated in nature. Perhaps just enough CAPE (~ensemble mean 500 J/KG) to get a stronger pulse storm or two, but the severe threat is low at this time. High pressure will make a brief appearance Tuesday night/Wednesday morning, but won`t last long as the next system moves into the region Wednesday night and Thursday. A strong closed low system is expected to develop and slide across the north plains Thursday afternoon. Current model timing and location of this system varies pretty significantly, so forecast confidence is low. A few solutions bring a more defined surface low with a warm front lifting over our eastern CWA resulting in a longer period of unstable air over the region. While other solutions have a very ill defined surface pressure pattern or keep the low east of our CWA altogether, resulting in a cooler, more stable airmass. It is a pretty large, slow moving system however, so rainfall may linger into Friday afternoon before exiting the region. Models are generous in their QPF, and the WPC values are currently over an inch for the eastern 2/3 of the CWA. Models really diverge toward the weekend and early next week. Some solutions try to build high amplitude ridge over the southwest CONUS, placing us into a persistent northwest flow aloft. Whereas other models maintain a more zonal flow first, before making the transition to northwest flow aloft. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 624 PM CDT Sun Jun 30 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions are forecast to persist until Monday morning, at which point sub-VFR stratus is forecast to materialize as low level moisture increases into the region on these southerly winds of 15 to 25 knots with gusts up to 35 knots. There could be a shower or thunderstorm at/near KMBG Monday morning (~11Z to 15Z). Otherwise, there are increasing chances at all four terminals for a shower or thunderstorm after 21Z Monday. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...KF LONG TERM...Serr AVIATION...Dorn