Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, 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
289 FXUS63 KFGF 251935 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 235 PM CDT Wed Sep 25 2024 .KEY MESSAGES... - Near critical fire weather is expected Thursday across southeastern North Dakota. There is a 20% that critical fire weather conditions develop. && .DISCUSSION... Issued at 223 PM CDT Wed Sep 25 2024 ...Synopsis... Quiet weather will continue through the evening and overnight hours due to upper level ridging. While ridging remains the main story through the weekend, there is a shortwave that will pass through on Thursday. As the ridge breaks down early next week, a trough propagates eastward, bringing with it cooler temperatures and very low chances for a few showers. ...Wind and Fire Weather Thursday... As the shortwave progresses eastward, its associated tightening pressure gradient in conjunction with a 40 knot 850 mb jet will promote gusty southerly winds. The area of highest wind looks to be confined to the Devils Lake Basin and far northern Red River Valley. In these areas, there is a 70% chance of seeing wind gusts of 40 mph or higher. Further south, winds are expected to be lighter, as winds aloft will not be as strong due to the more northern placement of the jet. While winds will be lower across the south, they are still anticipated to be breezy, with gusts up to 30 mph. RH values as low as 25% raise concerns for near critical fire weather. The largest limiting factor for critical fire weather is that the driest fuels and lowest RH values are across southeastern ND, while the highest forecasted winds are displaced to the north. Therefore, while critical fire with is not anticipated, there is a 20% chance that they do develop. This is most favored where the driest fuels and RH values can overlap with the higher winds, as the HREF shows when using dual probabilities for RH and sustained winds. ...Weekend and Beyond... Behind the passing shortwave, ridging will continue through Sunday with well above average temperatures. A trough coming off of the Pacific Sunday night into Monday will bring high temperatures down to their seasonal averages, which are in the 50s and 60s. Another period of breezy winds, this time out of the northwest, is anticipated behind the cold front. While the trough will bring enough forcing to provide some showers Monday and Tuesday, the placement and coverage of these are unknown. Therefore, POPs remain under 20% early next week, painting the idea of scattered showers. One other thing to note, breezy winds overnight should at least limit the frost risk. No clear signal exists for widespread frost early next week behind the cold front, but widespread low temperatures on either side of 40 degrees seems likely Tuesday and Wednesday mornings. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1257 PM CDT Wed Sep 25 2024 VFR conditions are confidently in the forecast throughout the TAF period. Upper ridging and surface high pressure will keep skies mostly clear today through tomorrow. Despite calm winds and clear skies in Minnesota, the chance for fog is very low due to such dry air mass in place. Increasing pressure gradient from the west will increase winds out of the south Thursday as early as sunrise Thursday, peaking during the afternoon with gusts 25-35kt in the forecast Thursday afternoon. Prior to increasing surface winds Thursday will be high confidence in LLWS over eastern North Dakota tonight starting between 00-03Z. Maximum winds will be around 40 kt at around 1kft above ground level. Included this in the DVL TAF, which may linger as late as 15Z as the boundary layer just starts to mix in the morning. Confidence decreases how far east LLWS gets, which brings a low chance LLWS impacts KGFK and KFAR tonight. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ DISCUSSION...Rafferty AVIATION...CJ