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
590 FXUS63 KBIS 142350 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 650 PM CDT Sun Jul 14 2024 .KEY MESSAGES... - Isolated to scattered severe storms are possible through this evening, but timing of the storms remains tricky. - Hail to the size of tennis balls and damaging wind gusts to 70 mph remain the main hazards. - Cooler weather returns to start the work week, with a modest warmup for the second part of the upcoming week. && .UPDATE... Issued at 650 PM CDT Sun Jul 14 2024 Surface low is analyzed in southeast Montana this evening, with a broad cu field and some weak radar returns continuing to develop north and east of the center, in northeast Montana and southwest North Dakota. These will be the areas to watch in the next couple of hours with a favorable synoptic environment in place, with SPC mesoanalysis showing 50-60 knots of bulk shear and generally uncapped 1500-2500 J/kg of MLCAPE, in line with an upper jet streak. The other area of concern is in north central North Dakota into the southern Canadian Prairies, where the strongest storms of the day have been so far along a wind shift. Made some adjustments to POPs based on latest NBM and current radar trends otherwise going forecast looks good for now. UPDATE Issued at 510 PM CDT Sun Jul 14 2024 Quick update for Severe Thunderstorm Watch issuance for northwest and north central North Dakota until midnight tonight. There is one supercell just across the International Border, north of Renville County, that will be crossing into North Dakota relatively soon. Otherwise main focus is on agitated cu field in the Glasgow area, with some radar returns showing up in far northeast Montana that will be moving into North Dakota through the evening. && .DISCUSSION... Issued at 216 PM CDT Sun Jul 14 2024 Current surface analysis places low over northeast Wyoming with inverted trough stretching up to the north into eastern Montana. Upper level analysis places broad high over the Four Corners region with low over far northern Manitoba. West-northwesterly flow remains over our area, which remains active with a series of short waves passing through. Initial wave now passing through northwestern North Dakota, with the secondary one over southwest Saskatchewan/northern Montana. Yet another wave noted upstream from there. Over our area, temperatures over most locations have climbed into the 80s knocking on the lower 90s. For this afternoon into tonight, the threat of severe weather remains in place but as has been going on for quite a while, the timing remains our fly in the ointment. A diverse group of solutions are being shown by latest CAMs, with some initiating convection with the initial wave moving through the area, while others are holding off until later. Some of the CAMs indicate convection developing with the initial wave in the not to distant future, but a quick look at our 19Z special sounding has a pretty pronounced cap over us, thus confidence in this occurring is diminishing, so now the best bet looks to be more towards the evening hours. Once convection does finally initiate, the potential is there for it to become quite robust. Deep layer shear is notably stronger than what we have had here the past few days, forecast to be about 50 kts across the area by early evening. This will combine with plenty of instability with MLCAPE values still anticipated to be in the 1500 to 2500 J/Kg range, plenty ample for severe convection. With the strong shear and ample instability, will maintain the threats previously forecast of tennis ball size hail and wind gusts to 70 mph. As for the tornadic threat, with the inverted trough sliding east, possibly closing off, enough lower level shear may be provided if a storm passes over the right area, though this setup is not ideal we cannot rule out a tornado or two if a discrete supercell were to develop early in the event. Convection will slide to the east/southeast through the evening/overnight hours. By Monday morning short waves will be pushing off to the east, but some showers/thunderstorms may linger over parts of northwest North Dakota into the James River Valley primarily during the morning hours. Upper flow does become a bit cyclonic in the afternoon as upper low with various waves swinging around it drops southward along the Manitoba/Ontario border, so can not rule out an increase in cloud cover in the afternoon, along with a few stray very light showers in the afternoon/early evening with additional activity overnight. Temperatures will be notably cooler as the north/northwesterly flow pulls in a cooler airmass, resulting in highs in the mid 70s to lower 80s. Flow aloft remains modestly cyclonic on Tuesday, continuing low chances for showers/weak storms. Stout ridge builds to our west and remains in place for the middle/end to the week. This will result in a modest warming trend returning temperatures to the 80s to around around 90 by Thursday continuing into the weekend. A few weak waves passing over the ridge will bring some low precipitation chances to the area towards the weekend. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 650 PM CDT Sun Jul 14 2024 Isolated to scattered thunderstorms are likely across much of western and central North Dakota through this evening and into tonight, but there is low confidence in any specific timing and location. Expect development to impact most TAF sites at some point, with the thunderstorm potential ending from west to east this evening and overnight. MVFR to potentially IFR conditions, as well as gusty and erratic winds, are possible in and around any thunderstorms. Winds on Monday will be from the north- northwest around 10 knots. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Jones DISCUSSION...JJS AVIATION...Jones