Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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498 FXUS63 KABR 260912 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 412 AM CDT Sun May 26 2024 .KEY MESSAGES... - A couple more shots at precipitation will be possible the remainder of the Memorial Day holiday weekend. There`s a 30-60 percent chance for showers and thunderstorms today into tonight. A 20-50 percent chance is possible Monday and Monday night, mainly east of the Missouri Valley. - Temperatures will remain around seasonal normals for the rest of the holiday weekend and on through the end of May. Stronger northwest breezes will kick in on Monday with gusts peaking between 25-35 mph. - At this point, later this week, thunderstorm chances (30-60%) look the best on Thursday afternoon through Thursday night. && .SHORT TERM /TODAY THROUGH MONDAY AFTERNOON/... Issued at 411 AM CDT Sun May 26 2024 A couple more rounds of precipitation chances will remain possible across this forecast area through the remainder of the holiday weekend. The first round is anticipated to arrive later today and persist into tonight and the second round will be during the daytime on Monday. Weak sfc high pressure remains in the vicinity of the forecast area early this morning leading to relatively quiet conditions. The last of Saturday`s rainfall has exited east into MN and now we`re just seeing a partly to mostly cloudy sky. Fog is beginning to develop across parts of our southwest zones. This is evident on satellite and from webcams positioned across parts of Jones, Lyman, Hughes, Hyde and Hand Counties. Expecting this fog and low stratus will continue to expand through the remainder of the pre-dawn hours in our southern zones as well as parts of the James Valley. Hi-res guidance shows it will fade away by mid-morning. The next system will be poised to our west by then. Mid-lvl s/w trough energy working around the base of the main mid-lvl low positioned over central Manitoba will track across the Dakotas later today into tonight. Sfc low pressure and an associated trough is progged to track across the region kicking off showers and elevated thunderstorms by late this morning into the mid afternoon hours across the Missouri Valley. This activity will shift east into the James Valley by late this afternoon and early evening before moving into west central Minnesota tonight. We aren`t expecting much in the way of organized severe weather with this system. There will be some modest instability for storms to feed off of as some models do prog MUCAPE values to reach upwards of around 1000-1500 J/kg. Bufkit forecast soundings show skinny CAPE soundings during the afternoon. Steep low level lapse rates look favorable and to a certain extent mid level lapse rates are respectable. However, deep layer shear is lacking however during the afternoon into the evening when CAM solutions depict a scattered line of convection crossing west to east across the CWA. Still, can`t rule out a strong storm or two, but again our forecast area is not outlooked for organized severe storms. This activity should be waning once it arrives in our eastern zones by late evening and early overnight. There should be somewhat a lull in the precip through the early to mid morning hours on Monday, but we reset things as we get into the daytime heating hours. The aforementioned sfc low will be positioned northeast of our area by then with the that mid-lvl trough axis working southward across the region helping to push a sfc cold front through. Stronger northwesterly flow at the sfc and aloft along with some cold air advection will help kick off more scattered showers and storms by midday Monday and Monday afternoon. This activity should remain mainly east of the Missouri Valley. A tightening gradient during the day will lead to increasing northwest winds that could gust between 25-35 mph. && .LONG TERM /MONDAY EVENING THROUGH SATURDAY/... Issued at 411 AM CDT Sun May 26 2024 When the period opens Monday night, models prog the upper low now straddling the Manitoba/Ontario border to warble around and swing southward across the region, bringing PVA-influenced showers south- southeastward across the CWA. Loss of daytime heating may weed out the weaker bits of convection, but there could be showers ongoing for several hours into the overnight Monday night. With the push of that upper circulation south and east away from the area on Tuesday, enter the upper level ridge that`s been forecast for several days now to push east across the CONUS`s mid-section Tuesday through Thursday. Overall, the steering flow pattern in the out periods has not changed all that much in 24 hours. The upper ridge axis continues to be forecast to be east of the CWA heading into Thursday morning. Models depict a "warm tongue" (700hpa temps ~+7C to +9C) aloft to march across the region with this upper level ridge. This may be enough of a cap to keep convection off to the west and north Wednesday afternoon and night. There is a low level jet that develops/spreads across the CWA Wednesday night. But, the nose of this LLJ is well off to the north/west of the CWA, and without something on which to focus (a low level forcing mechanism) convective potential, seems the LLJ and steepening mid-level lapse rates will be mostly academic. By Thursday afternoon, however, a surface frontal boundary is forecast to be working into central South Dakota, while mid-level temperatures begin a subtle cooling trend. Thursday afternoon through Thursday night appear to hold a decent chance for thunderstorms (30-60% chance of precipitation). Models continue to work toward a final solution (Ensemble Clusters) for Friday and Saturday steering flow winds and how to bring the next longwave trof through the central CONUS (progressive or not-so- progressive). For now, 20-30% chances for precipitation are smattered over Friday and Saturday while the uncertainty remains. Ensemble S.A table 850hpa temperature anomalies continue to support generally "near normal" temperatures throughout the period after Tuesday. While in northwest flow on Tuesday in the wake of that upper low, cooler air over west central Minnesota into far northeast South Dakota may make it feel a bit chilly over that area, with daytime highs Tuesday only topping out in the low to mid 60s. Expect temperatures to be a little bit warmer Wednesday through Saturday with highs generally warming into the 70s for much of the time throughout the CWA. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1240 AM CDT Sun May 26 2024 Terminals KABR,KATY,KPIR,KMBG KPIR is most likely to see some fog development toward morning with IFR vsby and cigs. However, KMBG and KATY may also see MVFR stratus develop. All sites are expected to be VFR by noon. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ SHORT TERM...Vipond LONG TERM...Dorn AVIATION...Vipond