RSS Mesoscale Discussions from Storm Prediction Center
WW 422 SEVERE TSTM MI WI LM 301340Z - 301900Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 422
NWS Storm Prediction Center Norman OK
840 AM CDT Tue Jun 30 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Upper Michigan
North-central and Northeast Wisconsin
Lake Michigan
* Effective this Tuesday morning and afternoon from 840 AM until
200 PM CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
SUMMARY...Scattered strong to severe thunderstorms are expected to
continue east-northeastward regionally, and may further increase
into midday with bouts of large hail and damaging winds possible.
The severe thunderstorm watch area is approximately along and 50
statute miles north and south of a line from 30 miles west of
Mosinee WI to 45 miles south of Escanaba MI. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 421...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
23025.
...Guyer
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WW 0422 Status Updates
STATUS REPORT ON WW 422
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..MEAD..06/30/26
ATTN...WFO...MQT...GRB...
STATUS REPORT FOR WS 422
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MIC109-301540-
MI
. MICHIGAN COUNTIES INCLUDED ARE
MENOMINEE
WIC009-015-029-041-061-067-069-071-073-075-078-083-087-097-115-
135-137-139-141-301540-
WI
. WISCONSIN COUNTIES INCLUDED ARE
BROWN CALUMET DOOR
FOREST KEWAUNEE LANGLADE
LINCOLN MANITOWOC MARATHON
MARINETTE MENOMINEE OCONTO
OUTAGAMIE PORTAGE SHAWANO
WAUPACA WAUSHARA WINNEBAGO
WOOD
LMZ521-522-301540-
CW
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WW 0421 Status Updates
STATUS REPORT ON WW 421
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 NE MCW TO
35 NW RST TO 45 WSW RHI.
..MEAD..06/30/26
ATTN...WFO...DMX...MPX...ARX...
STATUS REPORT FOR WS 421
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MNC039-045-099-109-157-169-301440-
MN
. MINNESOTA COUNTIES INCLUDED ARE
DODGE FILLMORE MOWER
OLMSTED WABASHA WINONA
WIC019-053-091-119-121-301440-
WI
. WISCONSIN COUNTIES INCLUDED ARE
CLARK JACKSON PEPIN
TAYLOR TREMPEALEAU
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
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No Mesoscale Discussions are in effect as of Tue Jun 30 14:42:10 UTC 2026.
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Tue Jun 30 2026
Valid 301300Z - 011200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR WESTERN
KANSAS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED RISK AND OVER THE UPPER GREAT LAKES AND PARTS OF THE
NORTHEAST...
...SUMMARY...
Scattered severe thunderstorms are probable over parts of the
central High Plains, with severe wind gusts (60 to 85 mph) being the
primary hazard during the late afternoon and evening.
...Synopsis...
Water-vapor imagery this morning shows a mid- to upper-level low
near the ND/Canadian border and a weak disturbance cresting a
mid-level ridge over southeastern ON and moving towards NY.
Downstream of a mid-level trough over the Southwest, a couple of
weak mid-level vorticity maxima over the southern and central High
Plains will slowly migrate northeast around the periphery of a
mid-level anticyclone centered over TN. A front will push east
across parts of the Upper Midwest and extend southwestward into the
central High Plains near a weak low. A weak lee trough/dryline will
focus storm development from western KS southward into the southern
High Plains.
...Southern/Central High Plains...
Perhaps associated with a weak disturbance, scattered thunderstorms
are forecast later this afternoon over the High Plains on the
western rim of richer low-level moisture and strong insolation.
Model guidance shows considerable erosion of the capping layer by
mid afternoon with MLCAPE ranging from 1500 J/kg over the TX South
Plains to 3500 J/kg over western KS. Initially higher-based
convection will gradually move east into richer moisture and promote
larger thunderstorm cores and increased potential for storm clusters
to develop. Large hail will be possible with any supercell activity
(i.e., most probable from the northern TX Panhandle into KS; 25-40
kt effective shear). However, very steep surface to 300-mb lapse
rates will favor strong evaporative cooling with the more intense
cores. Ample deep-layer shear for organized storms but
veering/backing of flow with height will aid in storm outflow
aggregating as linear clusters become the primary storm mode with
time. These organized but linear clusters will likely be efficient
in promoting severe wind gusts (60-85 mph) during the early evening,
coincident with a strengthening LLJ and WAA before this threat wanes
by late evening. Weaker deep-layer shear farther south in the
southern High Plains will likely limit both storm organization and
overall coverage of the wind risk.
...Upper Midwest/Great Lakes...
An ongoing area of showers and isolated thunderstorms over the upper
MS Valley will likely translate east-northeast today in conjunction
with a convectively augmented mid-level disturbance over southern MN
this morning. Ahead of this activity, a fetch of very rich moisture
will be maintained within south-southwesterly low-level flow. As
the boundary layer destabilizes ahead of this disturbance,
additional storms are forecast to develop later today within a very
to extremely unstable airmass. Ample tropospheric flow will support
organized storms, including supercells capable primarily of a
hail/wind risk and perhaps a tornado. By late evening,
strengthening WAA across NE and the mid MO Valley implies widely
scattered storms developing during the mid-late evening, with this
activity shifting northeast during the overnight. Isolated
hail/wind are the main threats with the stronger storms.
...Northeast...
A belt of 30-40 kt 500-mb northwesterly flow will reside across the
Northeast today. There is uncertainty regarding boundary layer
destabilization over portions of this region. Nonetheless, weak to
moderate destabilization is progged by model guidance with isolated
to scattered storms developing by early afternoon. A couple of
short-lived supercells are possible before one or more
clusters/bowing segments develop and spread south and eastward with
damaging wind potential.
...Southeastern US...
Located to the south of an upper high centered over the OH/TN
Valley, a very moist air mass will be present across much of the
region. Strong heating will yield moderate buoyancy by early
afternoon. Forecast soundings depict around 20-kt effective shear
which will aid in minor multicellular organization. Localized 50-60
mph gusts capable of isolated wind damage will probably accompany
the stronger storms.
..Smith/Dean.. 06/30/2026
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