


Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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652 FXUS63 KABR 091127 AAA AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 627 AM CDT Wed Jul 9 2025 .KEY MESSAGES... - Slight risk for severe storms across the region today and marginal risk for severe storms on Thursday. Hail up to 2 inches in diameter possible over central/north central SD by late this afternoon, with gusts over 70mph possible this evening into tonight. - Heat and humidity today (especially over central South Dakota), with highs in the 90s and heat indices approaching 100 degrees. && .UPDATE... Issued at 618 AM CDT Wed Jul 9 2025 See below for an aviation forecast discussion for the 12Z TAFs. && .DISCUSSION... Issued at 352 AM CDT Wed Jul 9 2025 At 3 AM CDT, temperatures have cooled into the 50s and 60s across the CWA. ACCAS clouds showing up over the central portion of the CWA on the night-time microphysics product. So, perhaps isolated to scattered elevated showers/thunderstorms may be developing within the next few hours over portions of, at least, the James River valley region. Winds are generally out of the southeast around 5 to 15 mph. Throughout the 7-day forecast, (from Ensemble Clusters Analysis) the flow pattern aloft continues to showcase the propagation of low amplitude ridges/trofs over North America, meaning the continuation of a somewhat active period of low level warm air and cold air advection, frontal passages and mid/upper level shortwaves/shortwave trofs over this region. Starting off with today, outside of any morning elevated convection firing on the leading edge of mid-level WAA and low level moisture advection on a low level jet over the region, will be focused on two boundaries over or near the CWA during peak heating when shortwave energy over Idaho and Montana lift out of the Rockies and head for the Dakotas. Models depict extreme instability (3000+ J/kg CAPE) today/tonight out ahead of the boundary and generally around 25- 30kts of deep layer shear (underneath a high pressure ridge axis aloft). Initially, CAM`s CI around 21Z may end up being delayed a few hours, if +13C air at 700hpa (depicted in the NAM and RAP now) is in fact in place over the boundaries in question. Mid-level lapse rates are also progged at 7-9C/km this afternoon/evening. One of the boundaries is a lee-side trof moving into the far western Dakotas by late afternoon (almost taking on a dry-line look and feel of quite dry (low dewpoints) behind the trof and rather moist upper 60s/low 70s along/ahead of the boundary. The other boundary, the lee-of-the- Black Hills surface trof/low) is progged to be doing its thing down across the I-90 corridor into south central SoDak by the end of peak heating today. Guidance is still saying convection (multi-cells and supercell structures expected initially with large hail potential) develops by early this evening and moves east-southeast across the CWA into the night-time hours potentially organizing into a linear storm mode (strong/damaging winds gusts). SPC currently has the western half of forecast zones in a slight risk (level 2 out of 5) for severe thunderstorms this afternoon/evening. Also, the latest iteration of heat indices continues to bring values close to 100 over parts of central SD this afternoon, but as of now it still seems potentially too brief/marginal to issue a headline for heat (100+ degree heat indices), although something to monitor. Heading into Thursday/Friday, one of these low amplitude low pressure trofs aloft are progged to spread from the Pacific Northwest over into the northern plains/southern Canada, bringing with it additional precipitation chances. Generally speaking, the CWA remains within a marginal risk (level 1 of 5) for severe thunderstorms Thursday/Thursday night. Still looks to be plenty of instability and steep lapse rates around heading into Thursday evening. But, deep layer shear necessary to produce any sort of organized severe weather threat Thursday afternoon/evening appears to be lacking at this time over this CWA. This upper level trof will sweep a strong cold front through the CWA Thursday night into Friday morning. Some post frontal precipitation Friday morning will be possible. Otherwise, the fropa will signal a break for a few days in precipitation chances. With winds through the column taking on a northerly component to them heading into the weekend, there could be a return of (Canada wildfire) smoke aloft on Saturday (per the 00Z/09th RRFS Smoke and Dust model output). Something else to monitor. Ensemble Clusters qpf analysis reveals the majority of Friday through Sunday should be precipitation free. The next noteworthy fropa out in the extended is currently timed to push through the CWA somewhere in the Monday night/Tuesday timeframe, and the Clusters qpf analysis does show there is some lower-bound qpf potential there on Tuesday. The Ensemble S.A. table for 850hpa anomalies also suggests that beyond any potential warm up into the low 90s by Monday, after the cold fropa early next week, cooler than normal temperatures could be taking over for the rest of the week. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 618 AM CDT Wed Jul 9 2025 Terminals KABR,KATY,KPIR,KMBG VFR conditions will continue through tonight. Thunderstorms could be near/over KPIR and KMBG in the early evening timeframe (~23Z through 03Z). These storms have the potential for large hail and severe thunderstorms wind gusts. Thunderstorms could be near/over the KABR/KATY terminals in the late evening/early overnight hours (~03Z through 07Z). && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...10 DISCUSSION...10 AVIATION...10