Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
564 FXUS63 KABR 291117 AAA AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 617 AM CDT Wed May 29 2024 .KEY MESSAGES... - Windy conditions will develop today across the forecast area. Southeast winds will increase by midday and this afternoon with gusts expected to range from 25-45 mph. The highest gusts will likely set up across the Missouri Valley and West River. - A 30-60 percent chance for showers and thunderstorms across central South Dakota, mainly after sunset tonight. This activity will track eastward overnight and into northeast South Dakota and west central Minnesota on Thursday where a 40-80 percent chance for precip will be possible. - Precipitation chances continue to litter the extended forecast period. But, right now Sunday evening holds the highest probability of seeing showers and thunderstorms (35-75%). && .UPDATE... Issued at 610 AM CDT Wed May 29 2024 See below for an aviation forecast discussion for the 12Z TAFs. && .SHORT TERM /TODAY THROUGH THURSDAY AFTERNOON/... Issued at 415 AM CDT Wed May 29 2024 The main forecast challenge in this period will revolve around an incoming storm system that is expected to deliver a round of showers and thunderstorms to the forecast area late tonight through Thursday. More to come on those details shortly. In the meantime, sfc high pressure sits across the Dakotas/Minnesota border region giving us clear skies and light winds early this morning. Temperatures will likely start off on the cool side prior to sunrise with readings around 40 degrees in spots. The sfc high will begin drifting east and away from us today. Shortwave ridging aloft building across the Dakotas will give us a mostly sunny to partly cloudy day with warming temperatures. The warm advection process will boost 850mb temps to +10C to +15C across our eastern zones to about +15C to near +20C across the Missouri Valley this afternoon. We should have no issues reaching daytime readings into the 70s to around 80 degrees. The one caveat to today`s nice weather will be the strong winds. A tightening pressure gradient between the sfc high to the east and a developing lee side trough west of the region will lead to strong southeast winds by midday and afternoon. The general feeling is that our eastern zones(James Valley and points east) will see afternoon gusts between 25-35mph. Locales farther west stand a better shot at realizing stronger wind speeds. The latest suite of ensemble guidance progs indicate highest probabilities of the highest gusts(40+mph) across north central SD, in particular Corson and Dewey Counties. BUFKIT profiles show the highest mixed-layer winds across locales along and west of the Missouri. Forecaster confidence not the highest in speeds reaching advisory crit; it could be a borderline marginal event in those far northwest zones of ours. Our dayshift will have to see how conditions trend as the day wears on. Focus will turn to increasing chances for convection late tonight in our west as a s/w trough crosses the Northern Rockies into the Northern High Plains. As this disturbance shifts east, lee side troughing deepens with sfc cyclogenesis expected. The sfc low is progged to track eastward out of MT into ND late tonight and Thursday morning. An associated warm front shift eastward from western into central SD will help to generate showers and thunderstorms by this evening west of our CWA. These are expected to track eastward into our western zones after sunset tonight, perhaps late tonight or closer to midnight. Some storms could be strong to severe across our western zones late tonight, but the ingredients aren`t the most favorable. There will be a narrow ribbon of instability developing across western SD into our far western zones with MUCAPE values around 1500 J/kg. Deep layer shear remains lacking in conjunction with this however. The best shear doesn`t set up until post fropa, after the quickly trailing cold front passes through closer to sunrise Thursday morning. SPC has highlighted western SD with a Slight Risk for severe weather where the best parameters for severe storms exist. With the loss of daytime heating and increasing stability, storms should loose their punch as they attempt to track any farther east of the Missouri River. The main threats with any of the strongest storms that get going will be large hail and damaging winds. Whatever may come of the initial convection late tonight is progged to track east across the forecast area through the early morning hours Thursday. Again, not anticipating any severe weather across our central and eastern zones during this point in time. The sfc cold front will sweep east during the day and generate more convection by midday and afternoon across our eastern zones. However, best instability looks to set up across our far southern zones into southeast SD. There may be a couple of strong to severe storms Thursday afternoon along and south of U.S. Highway 14 where a Marginal Risk for severe weather has been posted. && .LONG TERM /THURSDAY EVENING THROUGH TUESDAY/... Issued at 415 AM CDT Wed May 29 2024 At the start of the period, showers and thunderstorms are supposed to be ongoing, working east out of this CWA into Minnesota. Surface high pressure builds into the region for Friday, possibly into Saturday, before return flow sets up out ahead of a frontal passage progged for Sunday. More high pressure builds in behind that front, making things mostly dry again until perhaps Tuesday when another cold front (3rd cold front in the 7-day forecast?) may be working through the region. Aloft, clusters suggest there is general agreement in the various camps of solutions that the pattern flattens out with an occasional transient shortwave/fropa possible. It`s possible that one such shortwave, a somewhat stronger upper wave, will work across the northern plains/far southern Canada Tuesday and Tuesday night. A warming trend is still noted in the ensembles data, as well as the deterministic solutions, for the out periods and beyond. 850hpa temperatures warming to up 1.0 to 1.5 standard deviations above climo normal implies there is potential for temperatures to warm, at least, into the 80s across much of the CWA beyond day 3 (Friday) && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 610 AM CDT Wed May 29 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions are expected to prevail at all terminals through this TAF valid period. Guidance suggests some MVFR cigs could be creeping into the KMBG terminal after 09Z tonight. Otherwise, southeast winds settle in this morning across central and north central South Dakota, increasing to 20 to 30 knots by late this afternoon. Gusts of 35 to 40 knots will be possible as well. These conditions will gradually spread over into northeast South Dakota later on today, with breezy to windy southeasterly winds persisting tonight. Chances for showers and thunderstorms begin to increase late this evening into the overnight hours at KPIR and KMBG. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...Vipond LONG TERM...Dorn AVIATION...Dorn