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
108 FXUS63 KABR 201510 AAB AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 1010 AM CDT Sat Jul 20 2024 .KEY MESSAGES... - A plume of Canadian wildfire smoke at high altitudes will filter out the sunshine today. - There are daily precipitation chances (20 to 40 percent) today through Tuesday (mainly afternoon and evening activity). - Confidence is increasing for hot temperatures returning by the end of the week and next weekend. && .UPDATE... Issued at 1008 AM CDT Sat Jul 20 2024 The forecast remains on track this morning. No major changes are planned. && .SHORT TERM /TODAY THROUGH SUNDAY AFTERNOON/... Issued at 351 AM CDT Sat Jul 20 2024 The main issues in this period will revolve around fog and precip chances during the course of the next couple of days. Temperatures early this morning remain in the 60s with light and variable winds couple things notable on satl early this morning. First, low clouds and fog continues to develop across southeast SD and creeping gradually creeping northward. Second, a mid level trough axis located over the SD/MN border is pinwheeling southward. Tackling the fog prospects first as we go through the pre-dawn hours. Short-range hi-res guidance points to the low clouds/fog in southeast SD will continue moving northward and envelop our southern/southeastern zones. Additional new development is also certainly possible up/down the James Valley and other zones between the Jim and Mo Valleys. Its anticipated to persist for a while after sunrise, but should burn off by mid morning. Hi-res model guidance indicates a wide swath of Canadian wildfire smoke will drift southward across the Dakotas and MN today. It is expected to remain in the upper levels of the atmosphere so there is no air quality concerns, but it will act as a bit of a filter to the anticipated sunshine today. The aforementioned mid level trough will continue to move south and away from our forecast area today. The sfc tough associated with this feature will also continue to drift away from us into southeast SD/northwest IA today. Our region will remain in northerly flow aloft...between an upper ridge across the Great Basin into the Northern Rockies while a upper trough remains present across the Great Lakes into the New England. Our area will be closer to and the vicinity of the upper trough and we will continue to see weak mid level impulses flow through the region. Daytime heating with a humid air mass in place will lead to increasing instability this afternoon. Deep layer shear remains weak, so we expect afternoon convection to develop and remain widely scattered and mostly sub-severe. Some of the CAM solutions show very little in the way of any convection this afternoon and/or at best very isolated in coverage. So, confidence seems to be leaning toward more locales could remain dry. We`ll go ahead and repeat this same scenario during the daytime on Sunday. Although, some early morning convection could be possible as it drifts southward into our forecast area from a back door frontal boundary across northern MN/eastern ND. A sfc trough located across western SD during the day and again a repeat of atmospheric conditions by Sunday afternoon will lead to more scattered convection that should for the most part remain sub-severe. && .LONG TERM /SUNDAY EVENING THROUGH FRIDAY/... Issued at 351 AM CDT Sat Jul 20 2024 The region remains in northerly flow aloft with weak high pressure at the surface through the first half of the extended period. Pretty good model agreement in this scenario, which will also lead to a prolonged period of generally light winds with the broad surface high in place. That said, we keep a fairly moist air mass in place, with NBM dewpoints in the low to mid 60s through mid-week. With the coolish temps aloft, there`s still a signal showing up for daytime heating showers and thunderstorms Monday and Tuesday (eastern CWA) afternoons. Models continue to show upper level ridging building in by the end of the week, with high confidence supported by clustering analysis. Grand Ensemble continues to show 850mb temps reaching +20C or higher for areas along and west of the James River. Will continue to advertise high temps reaching the 90s by the end of the upcoming week as GEFS/ENS/GEPS all showing high probabilities (>60%) of reaching 90 degrees or higher across central SD and even into the James River valley. It would appear precipitation chances really start to wane as well. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 631 AM CDT Sat Jul 20 2024 Terminals KABR,KATY,KPIR,KMBG FG/BR is affecting the region this morning, especially at KATY/KPIR where VSBY has been down to 1/4 SM. Expect areas of MVFR/IFR VSBY across the region to burn off by around 14Z, making way for VFR conditions for the rest of the day. There is some potential for FG/BR tonight as well, mainly in the KATY region and will examine this in further TAF issuances. Smoke aloft is also blanketing the region and have inserted SCT250 in the TAF sites to account for this layer of smoke aloft. Also cannot rule out a stray thundershower or two across the area today, but with chances and areal coverage so small, will leave mention out of TAFs at this time unless something approaches on radar. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Wise SHORT TERM...Vipond LONG TERM...TMT AVIATION...TMT