Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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860 FXUS63 KABR 312318 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 618 PM CDT Fri May 31 2024 .KEY MESSAGES... - Saturday, there is the possibility (25-35% chance) of storms sneaking into south central South Dakota by late afternoon and then expanding eastward (40-50% chance) into parts of eastern South Dakota/west central Minnesota through the overnight hours. An isolated severe storm is possible, but the overall threat is low. - Attention turns to Sunday. Southerly winds will transport moisture into the region and a frontal boundary will likely be the focus for thunderstorm development. There is a slight risk (2 on scale of 5) of severe storms across the region. All hazards possible (wind, hail and tornadoes). - Temperatures are forecast to rise above normal this weekend into next week (highs in the 80s). && .UPDATE... Issued at 607 PM CDT Fri May 31 2024 Just some minor adjustments to sky cover and POPs as moisture moves off to the east. See below for update to the Aviation discussion... && .SHORT TERM /THIS EVENING THROUGH SATURDAY NIGHT/... Issued at 222 PM CDT Fri May 31 2024 Despite weak surface high pressure, a pretty well defined surface moisture boundary combined with upper level energy rounding a broad trough is enough to focus general showers from south central South Dakota to northeast South Dakota/west central Minnesota this afternoon. There is a slight (20%) chance of a rumble of thunder across far eastern South Dakota/west central Minnesota, but no strong storms are expected. Winds will generally be light and variable. The upper level pattern will be more or less zonal by Saturday. The surface pressure pattern will remain weak through the afternoon, but we will see a return flow pattern set up later Saturday afternoon through Sunday morning ahead of the next low pressure system. Warm air advection along with dewpoints returning to the upper 50s/low 60s, especially across south central South Dakota, will allow CAPE values to rise up around 500 J/KG. Combined with weak upper level energy and a developing LLJ into the overnight hours, there is the possibility (25-35% chance) of storms sneaking into the south central South Dakota counties initially by late afternoon, and then expanding eastward (40-50% chance) into parts of eastern South Dakota/west central Minnesota through the overnight hours. In fact, by 00Z Sunday 50% of LREF members have CAPE > 500 J/KG and 0-500 MB bulk shear > 30 kts over our western CWA. Therefore, a strong to severe storm or two is certainly not out of the question. Very uncertain on the overall extent of this convection through the overnight as well as how long and how much cloud cover will linger into Sunday morning. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 222 PM CDT Fri May 31 2024 The long term portion of the forecast begins on Sunday with a storm system impacting the region. Warm air advection, along with a 30-35 knot LLJ ahead of the surface low pressure may produce showers and thunderstorms during the morning hours. How long the morning convection lingers in the eastern CWA may limit the severe threat during the evening hours. An area of low pressure and associated cold front should progress eastward across the region Sunday afternoon through the evening hours. Strong to severe storms will be possible along the front as instability increases to 1000 to 2000 J/kg, along with 0-6 km bulk shear values 30-40 knots. The severe threat appears best between 22-04Z and east of the Missouri River valley. All hazards appear possible, including tornadoes. The storms should push east of the CWA by 6Z Monday, with a brief period of dry conditions possible on Monday. Another storm system should progress across the region late Monday night through Tuesday, bringing another round of strong to perhaps severe storms. The weather pattern beyond Tuesday favors northwest flow aloft with mainly dry conditions. Some model guidance suggests above average temperatures by the end of next week, while others indicate slightly below average due to an upper level trough closer to the region. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 607 PM CDT Fri May 31 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions for all terminals. Winds will be light as high pressure moves overhead tonight/early Saturday. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Connelly SHORT TERM...Serr LONG TERM...SD AVIATION...Connelly