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
512 FXUS63 KBIS 230549 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1249 AM CDT Sun Jun 23 2024 .KEY MESSAGES... - Isolated strong to severe thunderstorms are possible Sunday night into Monday morning across northwest and north central North Dakota, followed by a conditional threat for severe weather Monday afternoon and evening across the east. - Temperatures continue to warm through the weekend with the warmest day on Monday. Highs will range from the lower 80s to lower 90s. Then slightly cooler through the rest of the week (mainly upper 70s to upper 80s). - Thunderstorm chances return mid to late week. && .UPDATE... Issued at 1249 AM CDT Sun Jun 23 2024 At 1230 AM CDT, only a few isolated showers remained from just north of Lake Sakakawea to the northern James River Valley. The diminishing trend should continue through the night, and lightning is no longer anticipated. UPDATE Issued at 953 PM CDT Sat Jun 22 2024 The threat for severe weather is diminishing, although could remain into the early overnight hours. Severe thunderstorms across the southwest and southcentral have moved into South Dakota. The focus for strong to isolated severe storms now looks to be in the north to possibly some central areas into the early overnight hours. Here a weak upper level wave and front will push through tonight. MUCAPE of 500 to 1000 J/KG is on the lower side, however, 0 to 6 KM shear still remains 40 to 50 knots. Thus the overall threat for severe weather is low, however, an isolated threat will remain into the early overnight hours. Given the diminishing CAPE, hail up to the size of quarters will be possible going forward. Will maintain a wind threat of up to 70 MPH. DCAPE is up to 1000 J/KG, while 0 to 3 KM shear is at or above 30 knots. One other item to note for this update is the addition of patchy fog in the forecast. Soundings are generally more dry than last night. There still remains some lower level saturation and light winds in the forecast. Hi-res models also starting to pick up on some reduced visibilities later tonight into Sunday morning across the north and east. Thus added in some patchy fog in these areas. UPDATE Issued at 645 PM CDT Sat Jun 22 2024 Modest CAPE with ample shear has been enough to make a few isolated thunderstorms so far early this evening. Given the uncapped nature of this instability, isolated strong to severe storms will continue to be possible through the evening. The forcing is still weak to modest, which should limit the coverage of storms through the evening. However, any stronger storms that can develop will experience enough CAPE and shear to make large hail up to Ping Pong Ball size and wind gusts up to 70 mph. && .DISCUSSION... Issued at 304 PM CDT Sat Jun 22 2024 An upper level shortwave continues to move off into Minnesota as the parent trough moves overhead. A surface trough is currently the focus for scattered shower development as noted on radar, roughly along a line from Rolette county, down through Rugby, eastern Sheridan and Burleigh counties and arcing back to the east over McIntosh county to the South Dakota border. SPC mesoanalysis does suggest the presence of 500 to 1000 J/kg MLCAPE in place across all of western and central North Dakota so these showers should continue to increase in coverage and intensity as daytime heating increases. That being said, shear is currently weak where activity is developing and it should remain weak for the next few hours. Later this afternoon, we could have some more isolated development across the west which will have a similar instability environment, but much better shear. SPC mesoanalysis trends suggests effective shear could ramp up into the 35 to 45 knot range by the 22z to 01z time frame. Thus, there may be a window for a few isolated strong to severe storms later this afternoon and into the early evening hours. Any storms that do become organized will likely weaken quickly with the loss of daytime heating. We will continue to advertise hail to the size of quarters and winds to 60 mph as the primary threats, but larger hail may be possible if we can get any sustained rotating updrafts. After showers and storms fizzle, most of western and central North Dakota will see a mostly clear to partly cloudy sky overnight with lows in the 50s. Sunday will be dry for most of the day as an upper level ridge axis moves overhead. This will mean warmer temperatures for all of western and central North Dakota, with highs ranging from the mid to upper 70s over Rolette county, to the upper 80s and maybe even some lower 90s across the southwest. The ridge will then start to flatten as the axis moves off to the east and a subtle shortwave starts to skirt northwest part of the state by late evening. While most of the forcing will remain north of the International Border, there should be enough of a glancing blow to lead to some showers and storms across the northwest and eventually north central late Sunday evening and into the early Monday morning hours. While the magnitude of strong to severe thunderstorms is currently unclear, there will be favorable parameters in place with MLCAPE ranging from 500 to 1500+ J/kg and 40 to 50 knots of deep layer shear. If convection can tap into the favorable shear, some organization can be expected, probably in some sort of cluster or linear mode. For now, will continue to advertise hail to the size of quarters and wind gusts to 60 mph as the primary threats. Monday looks like it may end up being the warmest day of the forecast period for most with highs forecast to range from the lower 80s northwest to the lower 90s across the southeast. Monday could also see a conditional severe weather threat in the afternoon. The parameter space may end up being impressive across portions of the central and into the James River Valley. Some models suggest an environment characterized by 2500 to 3500 J/kg MLCAPE and deep layer shear ranging from 40 to 50 knots. That being said, confidence of seeing any storms is fairly low. Capping should keep the warm sector free of convection through the early to mid afternoon and most guidance suggests that a surface cold front will already be out of the area to our east before storms initiate. If these trends continue, it would not be surprising to see Monday completely dry for western and central North Dakota. Any western trend will need to be watched. Tuesday is then a bit cooler behind the cold front with highs in the mid 70s to mid 80s. Highs will be similar through the rest of the week until maybe Friday when some cooler temperatures potentially return. Various chances for showers and thunderstorms return Wednesday night through the rest of the week and into the weekend. CSU Machine Learning guidance suggests at least low chances for some severe storms on Thursday and Friday but we have a long ways to go before we get into specifics that far out. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1249 AM CDT Sun Jun 23 2024 VFR conditions are likely to prevail through the forecast period. A few showers remain possible over central North Dakota until around 08Z, but thunderstorms are no longer expected overnight. Some patchy fog could develop later tonight into Sunday morning, but confidence is not high enough to include a mention in the TAFs. Late Sunday evening, chances for thunderstorms will begin to increase in northwest North Dakota. Winds across western North Dakota will turn southeasterly Sunday afternoon and evening, increasing to 10-15 kts. Otherwise, winds will remain light. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Hollan DISCUSSION...ZH AVIATION...Hollan