![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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
639 FXUS63 KBIS 140609 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 109 AM CDT Wed Aug 14 2024 .KEY MESSAGES... - Low (20 to 40 percent) for showers with an occasional thunderstorm through tonight, followed by high chances (60 to 80 percent) on Wednesday. A few storms could become strong. - Torrential rainfall from slow moving thunderstorms could cause localized flash flooding on Wednesday. The highest risk is from south central North Dakota to the James River Valley. - High temperatures are forecast in the 70s and 80s through early next week. && .UPDATE... Issued at 108 AM CDT Wed Aug 14 2024 At 1 AM CDT, shower activity was widely scattered across the James and Sheyenne River Valley areas, with much more isolated activity extending back west towards Lake Tschida. Occasional lightning has been observed, but is far less frequent than earlier in the evening. Current conditions and trends were blended into the forecast for this update. UPDATE Issued at 1005 PM CDT Tue Aug 13 2024 Updated pops and sky cover late this evening based on the latest radar and satellite analysis. Heavy rain has ended over northern Morton and portions of western Burleigh counties. We can`t completely rule out additional rain later tonight over these areas, but at this time it looks like the next round of potentially heavy rain will be Wednesday. Very high PWATs will remain over the area, so any storms would have the potential to produce very high rainfall rates. UPDATE Issued at 709 PM CDT Tue Aug 13 2024 Thunderstorms continue over south central North Dakota. Strong moisture flux continues into central ND, and the Bismarck/Mandan area is right on the nose of the high PWATs lifting into the state and there may be a slight west to east inverted trough along the I-94 corridor. This was enough to provide a focus point for convection and convection continues to redevelop along this boundary. Fortunately for the Bismarck Mandan areas, the convection remains north of the Metropolitan area. We still have a couple Flood Advisories in effect. The first for the Bismarck Mandan area and although the rain has stopped, it will still take some time for the excess runoff to abate. The second Advisory is for portions of Burleigh and Morton Counties, north of Bismarck and Mandan. The ongoing convection remains mostly sub-severe, but with very high rainfall rates it`s not taking long for localized flooding in poor drainage areas. Reports of 2-4 inches of rain were pretty common around the Bismarck Mandan area, with some higher reports to the north. Most of the rain in the Bismarck Mandan area fell in around 20-40 minutes. Mesoscale models are still having a hard time resolving this evenings convection, so we manually adjusted pops east over the next few hours. Updated text products will be transmitted shortly. && .DISCUSSION... Issued at 237 PM CDT Tue Aug 13 2024 For this afternoon, shortwave energy continues bringing a few showers and thunderstorms through the forecast area. More recent CAMs continue to suggest more isolated coverage through this evening. As the wave moves further eastward, it enters a less favorable environment where instability decreases and effective shear is progged to be around 35 kts or less. So while another strong storm or two isn`t out of the question, the more likely scenario is isolated showers and with an occasional thunderstorm. Tonight through Wednesday is the more interesting period. In concurrence with the prior shift, agree that despite a marginal risk, severe weather potential looks pretty limited. RAP model projections suggest 0 to 6 km bulk shear limited at 20 kts or less for most areas most of the time, and often time 15 kts or less in areas with the best instability. More importantly for tonight through Wednesday is the potential for heavy rainfall. High pressure over the Great Lakes Region will help advect Gulf Stream moisture into the Dakotas on Wednesday, with mixed layer dewpoints likely in excess of 60 degrees. More robust shortwave energy, gradually becoming a more organized low, is projected to approach the area tonight and pass through the day Wednesday. Simultaneous surface low pressure will deepen with an elongated center most likely over Nebraska and/or South Dakota. As this system lifts to the northeast, weak upper flow will lead to the potential for training thunderstorms. Should this happen, the potential for very heavy rainfall and localized flooding exists. The HREF ensemble mean maintains lower amounts generally at an inch and a half or less. However, with thunderstorm activity and the aforementioned potential for training; the HREF max may play out in localized areas. This would mean an area, most likely in the south central (including the James River Valley) could see 4 to 5 inches of precipitation where any training occurs. One potential limiting factor to heavy rainfall is a lack of instability in the eastern half of the state. This is reflected in some CAMs which show more shower or thundershower activity rather than an organized thunderstorm complex. Beyond Wednesday, northwesterly flow aloft prevails through Friday with occasional shower and thunderstorm chances. Ridging looks to be prevalent for the weekend and into early next week with limited precipitation chances. Overall, expect seasonable to seasonably cool temperatures during a very gradual warming trend with highs mostly in the 70s and 80s. With cloudy skies and widespread rain, Wednesday looks to be the coolest day overall. One final miscellaneous note is that elevated smoke will persist over much of the area through tonight, with lesser areal coverage Wednesday through Wednesday night. A little near-surface smoke may also begin to filter into the west especially during the day Wednesday. Any visibility reductions from smoke should be limited. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 108 AM CDT Wed Aug 14 2024 Showers and thunderstorms are expected to become widespread across western and central North Dakota on Monday. Torrential rain will reduce visibility to IFR levels at times. MVFR to IFR ceilings are also expected to settle over most of the state early Wednesday morning, with gradual improvement from west to east in the afternoon and evening. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Hollan DISCUSSION...Telken AVIATION...Hollan