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
43
201 FXUS63 KGRB 132258 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 558 PM CDT Thu Jun 13 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Well above average temperatures are expected from Sunday into the middle of next week. Heat indices may surpass 90 degrees at times. - Next chances for rain/storms arrive Saturday night. It is too soon to determine if these storms will become severe, although locally heavy rainfall will be possible. - On and off chances for thunderstorms will continue through the middle of next week, although there is still some uncertainty with timing. Due to increasing heat and humidity, some stronger storms and locally heavy rainfall may be possible. && .DISCUSSION... Issued at 257 PM CDT Thu Jun 13 2024 Short Term...Tonight and Friday Isolated thunderstorms are possible in far northern Wisconsin through dusk as a jet streak moves across the region. Skies should clear overnight, and with diminishing winds and drier air low temperatures should be near or few degrees below normal. A weak surface high will move into Wisconsin Friday, with cooler and drier air. An upslope east northeast surface wind will likely produce clouds over central Wisconsin, and perhaps isolated showers in the afternoon. Did not include them in the forecast as confidence is low. Long Term...Friday Night Through Thursday After a brief dry spell on Friday to start the extended, active weather will then return to the region as mid-level flow amps up. Several chances for rain/storms will be possible through the weekend and into early next week as a persistent trough over the western CONUS ejects several fast-moving shortwaves into the western Great Lakes. Heavy rainfall will be a concern during this time as the WPC highlights northeast Wisconsin for receiving excessive rainfall Sunday and Monday. Attention will then turn to increasing temperatures mid-week as a ring of fire pattern advects a warm, moist airmass up into the Midwest. Saturday through Monday precip chances... As Canadian low pressure passes to our north Sunday and Monday, precip chances will enter the forecast area late Saturday into early Sunday out ahead of a warm front. Some elevated storms may be possible Saturday night given an abundance of low-level moisture and a strong LLJ (between 40 and 50 knots). Periods of moderate to heavy rain will be possible Sunday morning as PWATs increase to over 1.5". Temperatures on Sunday will be a hindrance to the forecast given the effect of lingering convection and cloud cover. This being said, current thinking is that temperatures on Sunday will be slightly lower than what model guidance is currently showing. Additional convection may develop late Sunday afternoon depending on airmass recovery time following Saturday night`s precip. However, main focus will be on storm chances for Monday as a cold front moves east across the forecast area. A first glance shows a favorable synoptic setup with placement under the right-rear quad of an upper-level jet and a nocturnal LLJ creating a convergent zone across western Wisconsin. Furthermore, deep Gulf moisture ingested by the parent low will allow dewpoints to reach the low to mid 70s across portions of central to east-central Wisconsin. Although it is currently too soon to tell, will continue to monitor potential for strong/severe storms as we get closer to the event. Rest of the extended... As the cold front departs to the southeast Monday evening, high amplitude mid-level flow is expected to settle in across the CONUS. A robust trough west of the Rockies will carve out a Bermuda ridge across the eastern US, placing much of the Midwest under a warm and moist southwesterly flow regime. This ring of fire pattern may prove problematic as temperatures could potentially soar into the low 90s Monday and Tuesday. However, there is some uncertainty on whether thunderstorm outflow from earlier in the week will act to shunt the warmer airmass further south, resulting in cooler temperatures than what model guidance is currently showing. Opted to go with the blended guidance for the time being due to low confidence. && .AVIATION...for 00Z TAF Issuance Issued at 558 PM CDT Thu Jun 13 2024 Isolated showers or thunderstorms are possible across far north- central Wisconsin early this evening; however, conditions should remain VFR. Showers will get close to RHI so will include a VCSH for the first few hours of this TAF period. Otherwise, the showers and thunderstorms should dissipate with the loss of daytime heating. VFR conditions are expected across the rest of the area and for the rest of the TAF period into Friday. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....RDM AVIATION.......Kurimski