Marine Weather and Tide Forecast for Boscobel, WI
May 21, 2024 1:01 PM CDT (18:01 UTC) Change Location
 | Sunrise 5:32 AM Sunset 8:25 PM Moonrise 5:53 PM Moonset 3:16 AM |
FXUS63 KARX 211742 AFDARX
Area Forecast Discussion National Weather Service La Crosse WI 1242 PM CDT Tue May 21 2024
KEY MESSAGES
- A significant severe weather event with a MODERATE RISK (Threat level 4 of 5) for severe storms today south of I90 and a Threat level 3 of 5 north of I90. Multiple rounds of storms continue morning and later this afternoon into evening. The highest severe threat appears to begin late afternoon and into the evening with damaging wind gusts and tornadoes being the primary threats, large hail is a secondary threat.
- With the multiple rounds of storms expected, a flood watch has been issued for southeast MN and northeast IA
- Small rain chances Wednesday with more rain chances Friday
DISCUSSION
Issued at 330 AM CDT Tue May 21 2024
Overview:
Water vapor satellite imagery, 500mb heights, and lightning showed a shortwave trough to the east with a broad trough over MT/WY and a closed low over Saskatchewan. Ahead of the broad trough, several clusters of storms were noted across parts of CO/NE/SD/IA/MN. At the surface, a 983 surface low was located over southeast Colorado with a stationary from northeast through KS/NE/IA into srn MN. A secondary surface low was near northwest IA with a boundary through central Iowa into southeast IA and northern IA. Storms were on the boundary and somewhat loosely organized over parts of IA/MN during the late evening, with both right movers and left movers. Some areas were lifting north with the increasing low level jet, while others were shifting east with the perturbations in the southwest flow aloft. The SPC mesoanalysis shows the SBCAPE axis from Kansas extending northeast toward western Iowa into southern MN. VAD wind profilers show the strong 35 to 50kt winds at 850 at DMX/EAX/TWX and 30kts locally. The effective wind shear was greater to the west of the local area at 06Z. The MPX 21.00Z sounding had 1.19" precipitable water (PWAT) and steep 7.5 C/km lapse rates.
Storms overnight and Tuesday morning:
Seasonably strong upper level jets are forecast from the Dakotas into Manitoba/Ontario and also from New Mexico into the Southern Plains; shifting eastward through 18Z. Portions of the Central/Northern Plains and Upper Mississippi Valley are forecast to experience upper level divergence/a coupled jet.
Meanwhile, a 500mb trough in the lee of the Rockies moves into the Plains with surface low pressure deepening over southwest MN/western IA. Moisture transport increases across the Plains and into the local area by 12Z, but really, ramps up through the Missouri River Valley. This then shifts east across western Iowa through 18Z. The low level jet across the Plains is forecast to strengthen 50 to 55kts through 12Z and makes progress eastward through 18z...but not as strong more in the 30 to 40kt range.
Due to the uptick in forcing overnight, progress of the perturbations and the shortwave trough, deepening of the surface low, and the favorable moisture and instability, continue to look for showers and thunderstorms to increase in coverage overnight. The CAMs are somewhat similar in showers and thunderstorms ongoing across much of the forecast area south of I94 through 12Z. While the instability is there, the deep layer wind shear and effective shear profiles remain more prohibitive for organized severe weather early on. We will continue to see strong to potentially severe storms this with damaging winds and some hail with the instability and forcing with heavy rain still a concern, especially along the boundaries and where storms repeat over the same area. A cluster of storms progress during the morning hours, these could tap into better shear with some severe storms. Some of the CAMS hint at bowing structures, while others do not.
Storms this afternoon and evening:
This afternoon, the 500mb trough over the Missouri River Valley will rotate northeast into the Upper Mississippi Valley. Surface low pressure is forecast to lift northeast along the boundary with the warm front lifting north and dragging a cold front across the forecast area during the afternoon and early evening. Surface based instability is forecast to increase with area 3000+J/kg. A ribbon of strong mid-level winds are forecast to increase across Nebraska into Iowa this afternoon and into Wisconsin this evening, resulting in lengthening hodographs and increasing/large 0-1/0-3 storm relative helicity values. The most recent CAMS indicate a lull in activity possibly 17-21Z. If this occurs, it would allow for additional destabilization/very steep lapse rate 8 deg C/+ ahead of the approaching cold front.
A line of broken storms is forecast to grow upscale across Iowa into western Wisconsin. It will be important to note any outflow boundaries and the location of the warm front, where supercells may develop. Short term mesoanalysis will be critical early on.
Damaging winds, large hail, tornadoes and heavy rain continue to be the main hazards. Due to the large 0-1/0-3 SRH values a few strong tornadoes could occur. Damaging winds of 75 to 90 mph and QLCS tornadoes will be possible with the line of storms.
The highest threat appears to be 20/21Z until 01-02Z with the storms exiting the forecast area by mid-afternoon south of I90.
Due to the above factors coming together this afternoon and early evening, the severe weather risk has been increased to a level 4 of 5.
Heavy Rain Potential:
Dodge and Mower County did see localized heavy rain, potentially 3 to 5 inches based on radar, but there could be some hail contamination in those values. PWAT values increase to 150-200% of normal by 12Z and continue through Today. Forecast soundings show warm cloud depths increasing through the day becoming more efficient rainfall producers. The 21.00 HRRR mean values of for 24hr rainfall show 1.5 to 2" through 22.00Z with max values of 3 to 7". Multiple rounds of storms are expected. Highest confidence is highest over parts of southeast MN where heavy rain occurred Monday and along the surface boundary. A broad look as the radar shows the increased convection along the boundary from eastern Nebraska across Iowa. The RAP has this boundary gradually lifting north during the day. Morning storms may affect how north it makes it.
The main negative will be the progressive nature of the storms; cloud level storm motions increase 20kts to 35kts to 45kts through the day. That being said, the multiple rounds should make up for it. For now will include southeast MN and northeast Iowa in a flood watch for flash flooding until 00Z for the rounds of morning and afternoon convection.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
Issued at 1242 PM CDT Tue May 21 2024
Main taf concerns are storm chances at both RST/LSE taf sites this afternoon into this evening
Then
MVFR/IFR conditions at both RST/LSE taf sites tonight into Wednesday morning. A cold front will move across the region this afternoon and evening.
Showers/storms will develop along the front and impact the taf sites late this afternoon and evening. There is potential for severe wind gusts of 50 knots or greater. For now have capped wind gusts to 45 knots and see how storms develop along front to introduce higher gusts in tempo group. Behind the front ceilings will lower into MVFR and continue into early Wednesday morning at both taf sites. Conditions will improve to VFR around 15z Wednesday at both taf sites.
ARX WATCHES/WARNINGS/ADVISORIES
WI...None.
MN...Flood Watch until 9 PM CDT this evening for MNZ079-086>088- 094>096.
IA...Flood Watch until 9 PM CDT this evening for IAZ008>011-018-019- 029-030.
Area Forecast Discussion National Weather Service La Crosse WI 1242 PM CDT Tue May 21 2024
KEY MESSAGES
- A significant severe weather event with a MODERATE RISK (Threat level 4 of 5) for severe storms today south of I90 and a Threat level 3 of 5 north of I90. Multiple rounds of storms continue morning and later this afternoon into evening. The highest severe threat appears to begin late afternoon and into the evening with damaging wind gusts and tornadoes being the primary threats, large hail is a secondary threat.
- With the multiple rounds of storms expected, a flood watch has been issued for southeast MN and northeast IA
- Small rain chances Wednesday with more rain chances Friday
DISCUSSION
Issued at 330 AM CDT Tue May 21 2024
Overview:
Water vapor satellite imagery, 500mb heights, and lightning showed a shortwave trough to the east with a broad trough over MT/WY and a closed low over Saskatchewan. Ahead of the broad trough, several clusters of storms were noted across parts of CO/NE/SD/IA/MN. At the surface, a 983 surface low was located over southeast Colorado with a stationary from northeast through KS/NE/IA into srn MN. A secondary surface low was near northwest IA with a boundary through central Iowa into southeast IA and northern IA. Storms were on the boundary and somewhat loosely organized over parts of IA/MN during the late evening, with both right movers and left movers. Some areas were lifting north with the increasing low level jet, while others were shifting east with the perturbations in the southwest flow aloft. The SPC mesoanalysis shows the SBCAPE axis from Kansas extending northeast toward western Iowa into southern MN. VAD wind profilers show the strong 35 to 50kt winds at 850 at DMX/EAX/TWX and 30kts locally. The effective wind shear was greater to the west of the local area at 06Z. The MPX 21.00Z sounding had 1.19" precipitable water (PWAT) and steep 7.5 C/km lapse rates.
Storms overnight and Tuesday morning:
Seasonably strong upper level jets are forecast from the Dakotas into Manitoba/Ontario and also from New Mexico into the Southern Plains; shifting eastward through 18Z. Portions of the Central/Northern Plains and Upper Mississippi Valley are forecast to experience upper level divergence/a coupled jet.
Meanwhile, a 500mb trough in the lee of the Rockies moves into the Plains with surface low pressure deepening over southwest MN/western IA. Moisture transport increases across the Plains and into the local area by 12Z, but really, ramps up through the Missouri River Valley. This then shifts east across western Iowa through 18Z. The low level jet across the Plains is forecast to strengthen 50 to 55kts through 12Z and makes progress eastward through 18z...but not as strong more in the 30 to 40kt range.
Due to the uptick in forcing overnight, progress of the perturbations and the shortwave trough, deepening of the surface low, and the favorable moisture and instability, continue to look for showers and thunderstorms to increase in coverage overnight. The CAMs are somewhat similar in showers and thunderstorms ongoing across much of the forecast area south of I94 through 12Z. While the instability is there, the deep layer wind shear and effective shear profiles remain more prohibitive for organized severe weather early on. We will continue to see strong to potentially severe storms this with damaging winds and some hail with the instability and forcing with heavy rain still a concern, especially along the boundaries and where storms repeat over the same area. A cluster of storms progress during the morning hours, these could tap into better shear with some severe storms. Some of the CAMS hint at bowing structures, while others do not.
Storms this afternoon and evening:
This afternoon, the 500mb trough over the Missouri River Valley will rotate northeast into the Upper Mississippi Valley. Surface low pressure is forecast to lift northeast along the boundary with the warm front lifting north and dragging a cold front across the forecast area during the afternoon and early evening. Surface based instability is forecast to increase with area 3000+J/kg. A ribbon of strong mid-level winds are forecast to increase across Nebraska into Iowa this afternoon and into Wisconsin this evening, resulting in lengthening hodographs and increasing/large 0-1/0-3 storm relative helicity values. The most recent CAMS indicate a lull in activity possibly 17-21Z. If this occurs, it would allow for additional destabilization/very steep lapse rate 8 deg C/+ ahead of the approaching cold front.
A line of broken storms is forecast to grow upscale across Iowa into western Wisconsin. It will be important to note any outflow boundaries and the location of the warm front, where supercells may develop. Short term mesoanalysis will be critical early on.
Damaging winds, large hail, tornadoes and heavy rain continue to be the main hazards. Due to the large 0-1/0-3 SRH values a few strong tornadoes could occur. Damaging winds of 75 to 90 mph and QLCS tornadoes will be possible with the line of storms.
The highest threat appears to be 20/21Z until 01-02Z with the storms exiting the forecast area by mid-afternoon south of I90.
Due to the above factors coming together this afternoon and early evening, the severe weather risk has been increased to a level 4 of 5.
Heavy Rain Potential:
Dodge and Mower County did see localized heavy rain, potentially 3 to 5 inches based on radar, but there could be some hail contamination in those values. PWAT values increase to 150-200% of normal by 12Z and continue through Today. Forecast soundings show warm cloud depths increasing through the day becoming more efficient rainfall producers. The 21.00 HRRR mean values of for 24hr rainfall show 1.5 to 2" through 22.00Z with max values of 3 to 7". Multiple rounds of storms are expected. Highest confidence is highest over parts of southeast MN where heavy rain occurred Monday and along the surface boundary. A broad look as the radar shows the increased convection along the boundary from eastern Nebraska across Iowa. The RAP has this boundary gradually lifting north during the day. Morning storms may affect how north it makes it.
The main negative will be the progressive nature of the storms; cloud level storm motions increase 20kts to 35kts to 45kts through the day. That being said, the multiple rounds should make up for it. For now will include southeast MN and northeast Iowa in a flood watch for flash flooding until 00Z for the rounds of morning and afternoon convection.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
Issued at 1242 PM CDT Tue May 21 2024
Main taf concerns are storm chances at both RST/LSE taf sites this afternoon into this evening
Then
MVFR/IFR conditions at both RST/LSE taf sites tonight into Wednesday morning. A cold front will move across the region this afternoon and evening.
Showers/storms will develop along the front and impact the taf sites late this afternoon and evening. There is potential for severe wind gusts of 50 knots or greater. For now have capped wind gusts to 45 knots and see how storms develop along front to introduce higher gusts in tempo group. Behind the front ceilings will lower into MVFR and continue into early Wednesday morning at both taf sites. Conditions will improve to VFR around 15z Wednesday at both taf sites.
ARX WATCHES/WARNINGS/ADVISORIES
WI...None.
MN...Flood Watch until 9 PM CDT this evening for MNZ079-086>088- 094>096.
IA...Flood Watch until 9 PM CDT this evening for IAZ008>011-018-019- 029-030.
| Airport | Dist | Age | Wind kt | Vis | Sky | Weather | Temp | DewPt | RH | inHg |
| KOVS BOSCOBEL,WI | 2 sm | 24 min | NE 09G17 | 3 sm | Overcast | Thunderstorm in Vicinity Rain Mist | 63°F | 59°F | 88% | 29.60 |
| KPDC PRAIRIE DU CHIEN MUNI,WI | 24 sm | 26 min | ENE 10G17 | 7 sm | Mostly Cloudy | Lt Rain | 63°F | 61°F | 94% | 29.61 |
La Crosse, WI,
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