Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000 FXUS63 KABR 160849 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 349 AM CDT Sun May 16 2021 .SHORT TERM...(Today through Monday Afternoon) Issued at 349 AM CDT Sun May 16 2021 Main focus for the short term will be the precipitation chances for today. Currently seeing light showers between Pierre-Mobridge- Gettysburg area are trying to make their way to the east-northeast. Farther southwest, showers and some rumbles of thunder (mainly in Nebraska where MUCAPE values exceed 250 J/kg) are occurring along the southern tier of counties in SD and starting to move into Jones/Lyman counties. This precipitation is tied to an area of deeper moisture, combined with some light warm air advection, both of which are expected to slide to the east through the day today. Expect the precipitation to largely impact the southern half of SD, but could see some of the showers currently near US 12 trying to hold together before running into the existing dry air in place, as seen on the 00Z KABR sounding. Hi-res models are showing a variety of solutions for QPF amounts with the precipitation. In most cases, the heaviest QPF (1-2.5in) is shown to the south of the CWA and that matches my expectations on where the current convection is located in northern Nebraska and area of MUCAPE. That being said, could see some higher amounts in the southern part of Jones/Lyman counties if some of the stronger precipitation areas continue their push to the northeast and a longer duration as the showers and embedded thunderstorms slide easterly through the morning hours. Farther north, models indicating the mid-level moisture overcoming most of the dry air in place and tied to the surface ridge that is lingering back across northern SD from the high centered in the Great Lakes. Overall started slight chance PoPs near Hwy 212 and then gradually increased to likelies over the Jones/Lyman area, following the better mid-level moisture and pockets of 700mb WAA. Models not showing the MUCAPE values pushing much farther to the north, so have limited the thunder potential to slight chances for most locations. For areas north of Hwy 212, expect high and some mid clouds this morning, which should try to thin near the ND border and then decrease over north central SD during the late afternoon. With varying cloud thickness and shower locations, there will be warmer highs to the north (mid-upper 70s), then cooler values over the southern part of the CWA (mid 60s south of Pierre). After today, the surface-850mb ridge slowly lifts north through Monday. Meanwhile, aloft the upper ridge in the northern stream jet will amplify over central Canada, with the upper low currently over northern CA and NV will slowly move towards the four corners area by 00Z Tuesday. Should see clouds decrease over most of the area tonight. Then as the sfc-850mb ridge moves northeast, the southeasterly flow will increase over the area and begin to drag the 850-700mb moisture back north and into the area on Monday (stalls south of the area tonight). A variety of ideas on timing of the moisture from the models, so will start to show an increasing trend in cloud cover from south to north on Monday afternoon. Temps on Monday will likely be similar to today over the north and then a little warmer over the southwestern part of the CWA. .LONG TERM...(Monday Evening through Saturday) Issued at 349 AM CDT Sun May 16 2021 The operational models and ensembles all point to a wetter pattern for our region from Monday night through Saturday. The period starts out with an upper level low pressure area over the southwest U.S. This will eject short waves into our region before the system opens and shears northeast across the central and northern plains through Wednesday night. The models and ensembles also show a much larger and stronger upper level low pressure area developing over the western U.S. into mid-week. This will be spinning short waves off and northeast across our region into Saturday. With this upper level flow through the week, warmer and more moist air will also be advecting into our region on south to southeast winds. Highs through the week are expected to be from 5 to 10 degrees above normal mainly in the mid 70s to the mid 80s. These warmer temperatures along with higher dew points will also result in better instability for the region resulting in off and on chances of thunderstorms. At this time, can`t pinpoint any one day for severe weather possibilities. && .AVIATION...(For the 06Z TAFS through 06Z Sunday Night) Issued at 1234 AM CDT Sun May 16 2021 Terminals KABR,KATY,KPIR,KMBG Showers, and possibly a few thunderstorms, will affect the southern part of the area late tonight into the day Sunday, including KPIR and possibly KATY. Periods of MVFR cigs and vsbys are possible with the precipitation. Otherwise, VFR conditions will prevail across the area overnight and through the day Sunday. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ SHORT TERM...SRF LONG TERM...Mohr AVIATION...Parkin

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