Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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258 FXUS63 KABR 150537 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 1237 AM CDT Sun Sep 15 2024 .KEY MESSAGES... - Several chances for precipitation next week. Greatest confidence for widespread rainfall will be Tuesday night into Wednesday with 50-70% chances. && .UPDATE... Issued at 647 PM CDT Sat Sep 14 2024 The overall trend with the ongoing storms over and east of the Missouri River has been a diminishing one. There are a couple of exceptions over Lyman County and west of Stanley/Jones County, where we have been seeing strengthening storms over the last hour that will need to be monitored for gusty winds of 50-60mph and quarter sized hail with the strongest storms. To the east, the outflow surged east and across Aberdeen-Redfield with gusts around 35 mph. Limited precipitation is expected east of this area (Aberdeen-Redfield). && .SHORT TERM /THIS EVENING THROUGH SUNDAY NIGHT/... Issued at 316 PM CDT Sat Sep 14 2024 The region will be between ridging over the eastern part of the country and a digging trough over the west coast through the near term period. This will keep a southwesterly flow over the Northern Plains, with some shortwave energy tracking across the CWA this evening, then again across central South Dakota Sunday night. At the surface, already seeing thunderstorms develop across parts of southwestern South Dakota this afternoon. These storms are developing along a boundary associated with low pressure over far western South Dakota and in an area where MUCAPE values are in the 1000-1500 J/kg and bulk shear is around 30 knots. The stronger instability looks to diminish through the afternoon, but will see about 700-900 J/kg remain over central South Dakota this evening, along with 35 to 45 knots of bulk shear. This will likely be enough to keep convection going through 03Z or so. Weak high pressure will bring quieter conditions overnight and through the day Sunday, then another boundary will set up from southwestern to central South Dakota. The best shear and instability will be over central South Dakota, but will not really be aligned timewise. CAMs hinting at some convective development, but the HRRR is currently the only one that shows any decent areal coverage, so will stick with POPs in the 20 to 40 percent range for now. Low temperatures tonight will range from the mid 50s across north central South Dakota to the mid 60s across northeastern South Dakota. High temperatures on Sunday will be in the mid 80s to the lower 90s. Lows Sunday night will be in the mid 60s. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 316 PM CDT Sat Sep 14 2024 The long term starts out Monday morning with a low pressure system to our west over MT. This low will move northeast and enter Canada before reaching our area. However, its warm and cold fronts will move more easterly and impact the area Wednesday afternoon through at least Wednesday. Thursday and Friday we are stuck in a blocking pattern with a low on the western side of the Rockies, a high over the Great Lakes region, and another low over the Carolinas. The EC ensemble shows a low moving west southwest across Canada on Saturday will help to break this pattern and another cold front will move across the area. The CMC ensemble and GEFS have some members showing a low in Canada but mostly lean towards a surface low circulating in the lee of the Rockies on Thursday and lasting through the end of the period. There is still a lot of time for models to come into agreement since this is at the far end of the period. There are several waves of possible precipitation through the period. The first starts early Tuesday with pretty light PoPs from the NBM of 20-30%. These chances move out of the region by late morning to early afternoon, leaving the rest of the day dry. Starting early Wednesday morning, another band comes through with much higher PoPs. Highest chances (70-75%) stay mainly south of I-90 with a band of 50-70% moving west to east across SD, decreasing to 30-45% as it moves into west central MN during the afternoon hours. Probability of more than 0.25" is generally between 50 and 60%, with slightly lower chances across north central SD. The next wave starts early Friday morning with widespread 30-40% chances that will stick around through the day Saturday. There is a lot of uncertainty with this event which accounts for the lower PoP values. Temperatures will be slowly decreasing through the period. Monday and Tuesday will continue our current pattern of above normal temperatures with highs in the mid 80s to around 90. Wednesday, Thursday and Friday are expected to be slightly cooler with highs in the upper 70s to low 80s. After a few days of clouds and rain chances, along with some fairly strong CAA, Saturday looks to be much more fall-like with highs in the mid 60s to low 70s. Afternoon wind gusts Monday and Tuesday are expected to be between 30 and 40 mph, mainly over central SD on Monday, but spreading to all of central and northeastern SD on Tuesday. Wednesday could see some gusts about of similar strength in higher elevation areas, but are expected to die out in the afternoon. The rest of the period is expected to be less windy. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1235 AM CDT Sun Sep 15 2024 Terminals KABR,KATY,KPIR,KMBG A low level jet across the area will result in wind shear conditions for a few hours tonight/early morning. Otherwise VFR conditions with some passing showers and decaying thunderstorms for the KABR/KATY terminals tonight. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...KF SHORT TERM...Parkin LONG TERM...KK AVIATION...Connelly