Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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476 FXUS63 KABR 040513 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 1213 AM CDT Thu Jul 4 2024 .KEY MESSAGES... - Clouds, spotty rain showers, and a few weak thunderstorms will persist across the area through the day Thursday, making for a cool and soggy Fourth of July. - The active weather pattern of showers and thunderstorms persists Friday into the weekend. && .UPDATE... Issued at 607 PM CDT Wed Jul 3 2024 Showers have reached the central SD cwa border this evening, so overall precip trends are on track if perhaps too quick by an hour or two. Otherwise, the forecast looks good this evening, and no major changes are planned. && .SHORT TERM /THIS EVENING THROUGH THURSDAY NIGHT/... Issued at 233 PM CDT Wed Jul 3 2024 Weak ridge ahead of a shortwave embedded within this baggy trough responsible for fairly pleasant conditions, though there are strong storms just south of the White river, with the elevated band of weak convection that lifted through Jones and Lyman counties earlier having nearly dissipated. The atmosphere generally remains weakly unstable however, with cumulus development along the SD/ND state line and across the Sisseton hills. As the afternoon/evening progresses, convection in northwest/west central South Dakota is expected to move into the western CWA, though we cant rule out storms (non-severe) forming along and south of the While river also drifting into the southern CWA. Convection should be more widespread overnight, however some of the CAMS have noticeable gaps, but eventually coalesce around the developing mid level trough. This trough evolves into a low over eastern South Dakota tonight and continues to drifts east. Cool air on the backside of this feature will result in continued weak instability for wrap around showers/weak thunderstorms. HREF probability of 2 inches total QPF is up to 40 percent in a few bullseyes across the James into the Coteau, but more broadly a 40- 70% chance for an inch total. NBM probabilities are lower and focused more into the FSD CWA. GEFS plumes range between 1/2 inch to 2 inches with a choice ensemble member or two up to 4 inches. Needless to say, not much certainty with respect to total moisture, but it does look like low clouds and light precipitation will linger across east river well enough into Thursday to influence evening activities. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Issued at 233 PM CDT Wed Jul 3 2024 Clusters agree well on the 500mb low over the Upper Midwest over MN/WI/IA area Friday morning. The only difference is that Cluster 4 (10% GEFS/20% ENS) keeps it more of an open wave. The system will be stacked to the surface with an occluded low over the same area. Through the day into the evening this low and its upper level system will continue its track east/northeast. Clusters indicate lingering precip on the back end of this system early Friday. NBM shows this well with lingering 15-20% pops mainly over our extreme southeastern CWA. Shortwave energy behind the low and ahead of the next system will bring scattered rain/thunder chances through the day as northwest flow continues. Pops increase to 25-40% during peak heating hours/daytime instability before decreasing by sunset. However, this incoming wave will keep pop chances of 20-30% around and west of the Mo River late Friday night into early Saturday. Highs for Friday will still be on the cooler side, ranging from the mid 70s to around 80 and lows in the 50s. This shortwave is forecasted to swing in from the northwest Saturday. Still a little bit of a difference in the wave`s intensity and location between the Clusters. A cold front is forecasted to push east/southeast over the CWA through the day, associated with the surface low in southern Canada. There is also a lee side low/trough that develops over the Central Plains as well aiding in daytime moisture. We see more of a split over the CWA with the better moisture to our north and south. By late afternoon/evening pops increase to 35-50%. Ahead of the front, temps are forecasted to warm into the 80s and dewpoints rising in the upper 50s. GEFS indicates SB Cape increasing to 1000-1500 j/kg over northeastern/eastern SD into western MN and lapse rates of 6-7C are forecasted along with marginal shear. However, GEFS seems to be the most aggressive in the instability compared to EC which is much more relaxed at this point. We will also be dealing with some clouds that could hinder some stronger instability. So we will have to wait closer to time when models agree more. CSU has a 5-15% prob of severe over our parts of northeastern to eastern SD into western MN. As the system moves east/southeast, ongoing chances of showers and thunderstorms are possible, peaking Sunday afternoon (20-50% pops) with daytime instability, highest over the James River Valley and eastward. By early next week, the +PNA pattern continues with the ridge starting to push east becoming broad and over much of the CONUS. Highs are forecasted to warm into the 80s and possibly into the 90s by midweek. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1213 AM CDT Thu Jul 4 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions will prevail through Thursday at most sites except KATY where MVFR cigs are expected to move in during the morning. MVFR cigs/vsby are possible in heavier showers at other sites, as well. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Wise SHORT TERM...Connelly LONG TERM...MMM AVIATION...Wise