Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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
547 FXUS63 KGRB 261128 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 628 AM CDT Wed Jun 26 2024 Updated aviation portion for 12Z TAF issuance .KEY MESSAGES... - Cooler and less humid weather is expected today, along with a slight chance of showers and possibly a thunderstorm. - Showers and thunderstorms will bring periods of rain to the region Friday and Friday night. Probabilities for heavy rain greater than 1 inch over a 24 hour period are relatively low at less than 10% through 7 am Saturday. The severe weather threat is also low at this time. - Some rivers and streams will remain above bankfull and near flood stage into the middle of the week. && .DISCUSSION... Issued at 232 AM CDT Wed Jun 26 2024 Short Term...Today...Tonight...and Thursday A mid level trough with an attendant shortwave, seen on water vapor imagery over northern Minnesota, will track through northern Wisconsin today. The shortwave will bring increasing clouds and may produce some isolated showers and a rumble or two of thunder with SBCAPE values around 500 J/kg. Temperatures will be cooler today; ranging from around 70 across the north to the upper 70s across central and east-central Wisconsin away from the lake. High pressure building in across the western Great Lakes will keep the weather dry tonight and Thursday. Cool weather will continue as low fall into the upper 40s across the north tonight, with lower 50s across central and east-central Wisconsin. Highs on Thursday are only expected to rise into the lower to middle 70s. Long Term...Thursday Night Through Tuesday Focus of this forecast revolves around thunderstorm and severe weather potential during the Friday and Friday night timeframe. Friday and Friday night...Within low amplitude flow along the US- Canadian border, shortwave energy traversing east will bring a surge of deeper moisture to the region. Precipitable water (pwats) values are forecast to climb to 160-180% of normal by Friday afternoon. In general, models point towards a low impulse shortwave pushing into the region on Friday afternoon ahead of the main shortwave and cold front which will still be positioned over the northern Plains and northern Mississippi Valley respectively. This shortwave will aid in generating large scale ascent within the warm advection zone well ahead of the front and prior to the instability moving into the region. In this environment, deep saturation with above normal pwats will lead to a chance of widespread rain, but the severe threat is low through Friday afternoon. The cold front moves through on Friday night and models project a ribbon of elevated instability up to 1000 j/kg will be present along the boundary. Deep layer shear will be increasing by this time to around 30-40 kts. Guidance is not ambitious with precip chances or qpf along the front, which may have to due with precip earlier in the day. At this point, will pass along concerns to the next shift but continue to downplay severe weather chances as low. Probabilities for heavy rain greater than 1 inch over a 24 hour period are also relatively low at less than 10% through 7 am Saturday. Rest of the forecast...Relatively quiet weather will prevail this weekend with seasonable temperatures and humidity levels falling by Sunday. The next chance of thunderstorms will arrive by next Tuesday. && .AVIATION...for 12Z TAF Issuance Issued at 628 AM CDT Wed Jun 26 2024 VFR conditions are expected through the TAF period. A few mid and high clouds will continue to stream in at times across the area this morning. These mid and high clouds will exit later this morning, with lower cumulus clouds developing through the morning and continuing into the afternoon. There could be a few sprinkles or showers from these clouds as a weak boundary drops through the area, but it appears conditions will stay VFR. Gradual clearing is expected this evening into the overnight hours. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Kurimski/MPC AVIATION.......Kurimski