Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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050 FXUS63 KABR 280921 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 421 AM CDT Tue May 28 2024 .KEY MESSAGES... - Dry conditions return to the forecast area today and Wednesday as high pressure takes hold. Increasing southeast winds expected on Wednesday with gusts of 25-45 mph. The strongest gusts will be felt across north central South Dakota and parts of the Missouri Valley. - There is a 60-85% probability of precipitation west of the James River valley and 20-60% probability of precipitation from the James River valley over to the Minnesota/South Dakota border Wednesday night. - There is a 55-95% probability of precipitation from east of the Missouri River valley over into west central Minnesota and 20-55% probability throughout and west of the Missouri River valley on Thursday. - Temperatures are forecast to continue near to slightly below normal, in the upper 60s to mid 70s, Thursday and Friday before a gradual warming trend begins on Saturday and continues into Monday. && .SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/... Issued at 419 AM CDT Tue May 28 2024 Ongoing shower activity early this morning across our eastern forecast zones will be gone and exited from our CWA for the most part toward day break. This will leave us with a dry day for a change with sfc high pressure progged to gradually build in from the north. Northerly flow at the sfc and aloft will pull in a cooler air mass into our area, especially noticeable across our eastern zones. Model guidance progs the cold air advection process to drive 850mb temps down into the +5C to +7C range this afternoon from the James Valley east into west central MN. A thickening CU field across the east may also aid in keeping temps below normal for late May. Farther west in the Missouri Valley, daytime readings will be closer to normal. Overnight, high pressure will settle across the eastern Dakotas and Minnesota. Clear skies and light winds in the east should allow temps to bottom out around 40 degrees by Wednesday morning, especially across the James Valley. The sfc high pressure system will pull away eastward and farther away from us on Wednesday. Increasing heights in the mid levels by the latter half of today into Wednesday indicate an upper ridge will be building across the Dakotas for midweek. This is in response to the next upper level trough this is progged to shift into the PacNW by tomorrow. Winds turn more south to southeasterly tomorrow allowing a warmer air mass to displace the cooler one. Temperatures should be back close to normal for daytime highs by afternoon. The one concern on Wednesday will be the wind speeds. A tightening gradient between the aforementioned high pressure east and developing low pressure across the Northern High Plains will begin to put the squeeze on across western and central SD by midday and afternoon. Wind probabilities among ensemble guidance pegs north central SD as having the best chances for seeing gusts approach or exceed advisory criteria by the mid to late afternoon hours. Generally speaking, a gusty afternoon with speeds between 25-45 mph will be possible...with the highest gusts by afar across our central and western CWA. && .LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/... Issued at 419 AM CDT Tue May 28 2024 In-house ensemble-powered PoPs continue to ratchet up the chances for showers and thunderstorms Wednesday night (60-85% probability west of the James River valley and 20-60% probability from the James River valley over to the Minnesota/South Dakota border) and Thursday (55-95% probability from east of the Missouri River valley over into west central Minnesota and 20-55% probability throughout and west of the Missouri River valley). CAM solutions for Wednesday night, however, do not presently support such high PoP values. So, the tug- of-war between ensembles and CAMs begins, and the trend in PoPs in these two camps of precipitation forecast will have to be monitored closely over the next couple of days. Once the frontal boundary and upper support for it pushes east of the region Thursday night, the flow pattern aloft begins to flatten and surface high pressure builds into the region. Transient/fast flow aloft will make timing periods of surface fropas and surface high pressure systems a bit tenuous from Friday onward. Right now, there is actually some support amongst GSM camps for seeing a decent fropa sweep through the CWA on Sunday (day 6) during peak/daytime heating, and maybe there could be some convective potential there? By the end of the period and beyond, the trend toward a (dirty) ridge building over the western two-thirds of the CONUS and temperatures warming into (at least) the 80s is still showing up in the ensembles (box-and-whiskers/S.A anomaly tables) and deterministic (850hpa and 925hpa thermal progs) model data. Worth noting, for a couple of days now, the in-house ensembles probabilities for temperature reaching 90F degrees or warmer over central South Dakota next Monday has been hovering in the 10-20% range. Beyond that, the same probabilistic data for days 8 through 10 increases to 20-50%. Another trend to monitor in the coming days. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1234 AM CDT Tue May 28 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions for all terminals. There are a few light showers out there but probability for these to occur at any particular station is low. However, did include a prevailing mention of VCSH at KABR and KATY during the pre-dawn hours. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ SHORT TERM...Vipond LONG TERM...Dorn AVIATION...Vipond