Mesoscale Discussion 1826
NWS Storm Prediction Center Norman OK
0525 AM CDT Mon Aug 03 2026

Areas affected...central and eastern North Dakota into northwest
Minnesota

Concerning...Severe potential...Watch unlikely 

Valid 031025Z - 031230Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated large hail is possible from storms across the
northern Plains and Upper Midwest this morning.

DISCUSSION...An expansive area of storms has developed across North
Dakota and northwest Minnesota within a broad region of isentropic
ascent. 1500 to 2000 J/kg MUCAPE and effective shear of 30 to 35
knots (per SPC mesoanalysis) will support some organization,
including the potential for some supercell structures. Overall,
expect mostly sub-severe high-based storms, but a few of the
stronger storms may be capable of large hail. No watch is expected.

..Bentley/Smith.. 08/03/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FGF...ABR...BIS...

LAT...LON   45950172 47700038 48409935 49129615 49029465 48759448
            47689573 46399715 46009827 45819950 45950172 

MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1254 AM CDT Mon Aug 03 2026

Valid 031200Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF NORTHERN MINNESOTA INTO
ADJACENT PORTIONS OF THE EASTERN DAKOTAS...

...SUMMARY...
Strong to severe thunderstorm development appears possible today
across parts of northern Minnesota into adjacent portions of the
eastern Dakotas, as well as across the eastern Arizona international
border vicinity and parts of the northern Mid Atlantic through
western New England.

...Discussion...
A compact, but fairly deep, lower/mid-tropospheric cyclone over the
Canadian Prairies is forecast to migrate across northern Manitoba
into western Hudson Bay today through tonight.  One initial trailing
cold front is already advancing into the northern Great Plains, with
a more substantive cold front approaching the international border
and forecast to overtake it by mid afternoon, roughly across the
northwestern Minnesota through southeastern North Dakota, central
South Dakota, and western Nebraska vicinity.  

As a notable upstream mid-level short wave trough accelerates across
the northern U.S. Rockies, toward northwestern Ontario, it appears
that a secondary surface low emerging from Wyoming will weaken while
migrating northeast of the Black Hills through the adjacent middle
Missouri Valley early today.  Another surface low may form along the
front across northern Minnesota into northwestern Ontario this
evening, but it appears that the most rapid deepening will occur
north of Lake Superior overnight.

To the south and southwest of the mid-level wave, models indicate
that mid-level ridging will build across the Southwest during the
day, with highest heights becoming centered along an axis across
southwestern through central Arizona into north central New Mexico
by late afternoon.

Within the downstream westerlies, a notable mid-level trough is
forecast to pivot east and northeast of the lower Great Lakes
through New England.  As it does, a remnant perturbation digging
toward the southern Appalachians may evolve into a weak mid-level
low across the Southeast, cut off from the westerlies.

...Northern Great Plains into Upper Midwest...
The influence of possible early period convection and associated
cloud cover on destabilization and convective potential later today
across parts of the central and eastern Dakotas into Minnesota
remains a bit unclear.  However, by mid to late afternoon, guidance
generally indicates that a fairly sharp quasi-stationary
near-surface baroclinic zone will evolve across northwestern
Minnesota through southeastern North Dakota.  It appears that this
may become a focus for at least a narrow corridor of modest
boundary-layer destabilization, coincident with strengthening south
to southwesterly lower/mid-tropospheric wind fields (including
30-40+ kt around 850 mb and 50-70 kt around 500 mb).  This may
provide a window of opportunity for strong to severe storm
development, including a couple of supercells, by this evening,
before the front overtakes the instability axis with the passage of
the frontal wave.

...Southeastern Arizona/adjacent New Mexico...
Low-level moisture appears likely to remain relatively modest across
central and southern Arizona, with strong daytime heating and mixing
lowering surface dew points through the mid to lower 50s F by late
afternoon.  However, along the southern periphery of the stronger
mid-level ridging, it appears that this may support at least
moderate boundary layer CAPE near the international border vicinity,
beneath 25+ kt east-northeasterly mid-level steering flow. 

The higher terrain either side of the southern Arizona/New Mexico
state border will provide potential for a more substantive
clustering of convection, which may propagate across and south of
the international border by early this evening.  If preceding
thunderstorm development, initially developing in the unstable
environment near the international border, does not generate too
much stabilizing outflow, it is possible that this could become
supportive of a swath of strong to severe wind gusts, aided by
evaporative cooling in a deeply mixed sub-cloud layer with 40-50 F
temperature/dew point spreads.

...Northern Mid Atlantic through western New England...
Along and ahead of a weak cold front, trailing a deepening surface
low migrating northeastward toward the lower St. Lawrence Valley,
boundary-layer destabilization will probably be slowed, if not
inhibited, by weak mid-level lapse rates and early day cloud
cover/precipitation,  However, strengthening deep-layer wind fields
and shear will potentially become more supportive of organized
thunderstorm development with a risk for damaging wind gusts and
perhaps a tornado or two, if pre-frontal breaks in cloud cover can
allow for sufficient destabilization with daytime heating.

..Kerr/Supinie.. 08/03/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1229 AM CDT Mon Aug 03 2026

Valid 041200Z - 051200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN SOUTHEAST
ARIZONA...SOUTH-CENTRAL COLORADO...NORTH-CENTRAL AND NORTHEAST NEW
MEXICO...AND PORTIONS OF THE CAROLINAS...

...SUMMARY...
Isolated severe storms capable of severe wind gusts and marginally
severe hail appear possible in southeast Arizona, south-central
Colorado, and north-central and northeast New Mexico Tuesday
afternoon and evening. Locally damaging winds may occur with
stronger storms in the Carolinas.

...Synopsis...

A broad, cyclonic flow regime is forecast from the northern Rockies
into the Great Lakes, to the north of an elongating upper high over
the Lower CO Valley into the southern Rockies. Within that pattern,
there is a model signal that a low-amplitude disturbance and
associated mid-level wind maximum will move through the northern
Plains and mid MO Valley. Elsewhere, an upper low centered over the
southern Appalachians Tuesday morning is expected to weaken while
slowly shifting north-northwest. 

At the surface, a front will move into the upper Great Lakes with
the boundary trailing southwest through the mid MO Valley into the
southern High Plains. A weak surface low may evolve along the front
over the mid or lower MO Valley Tuesday afternoon into evening. 


...Southeast Arizona...

Widely scattered thunderstorms are anticipated by mid afternoon
along the Gila Mountains and high terrain nearer to the
international border within a moderately unstable environment with
MLCAPE up to 1000-1500 J/kg. The presence of a deep, well-mixed
boundary layer will enhance evaporative cooling potential in the
sub-cloud layer with an associated risk for locally severe wind
gusts as storms advance southwest into the lower desert during the
late afternoon into evening. Some threat for marginally severe hail
may exist with the storms developing along the international border
owing to slightly stronger deep-layer shear.


...South-central Colorado and north-central and northeast New
Mexico...

A relatively small spatial corridor of modest instability and 30-35
kt of deep-layer shear is forecast to materialize in the lee of the
Sangre De Cristo Mountains Tuesday afternoon and evening. The
favored corridor extends from where the surface front intersects the
high terrain northward within the immediate post-frontal upslope.
Several of the 00Z CAMs indicate the potential for isolated to
widely scattered storms capable of a few occurrences of marginally
severe hail and/or locally severe wind gusts.


...Carolinas...

Forcing for ascent associated with the deep-layer low is expected to
contribute to an increase in thunderstorms through the day. Where
stronger heating can occur, the presence of a moist boundary layer
will support MLCAPE up to 1000-2000 J/kg. While stronger upper-level
winds are forecast within the eastern periphery of the low, vertical
shear through the lower half of the storm depth is expected to
remain relatively weak, limiting the potential for storm
organization. Nonetheless, steepening low-level lapse rates and a
high precipitable water may enhance wet microburst potential, with a
few damaging wind gusts possible.


...Middle and Lower Missouri Valley into the upper Midwest...

Consensus of the 00Z models suggests the majority of thunderstorm
activity will likely remain elevated to the north of the front in NE
and IA within a strongly sheared, but only marginally unstable
environment. Poor mid-level lapse rates are expected to limit any
severe hail threat. There is some model signal for isolated storm
development during the afternoon into evening along the front from
the lower MO Valley into southern/eastern WI. However, given that
there is considerable model variability in the degree of instability
ahead of the boundary, and that vertical shear will be somewhat
marginal across the warm sector, no probabilities will be included
in this forecast.

..Mead.. 08/03/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0225 AM CDT Mon Aug 03 2026

Valid 051200Z - 061200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN
KANSAS INTO WEST-CENTRAL ILLINOIS...OVER PORTIONS OF SOUTHERN
ARIZONA...AND FROM SOUTH-CENTRAL COLORADO INTO NORTHEAST NEW
MEXICO...

...SUMMARY...
Isolated severe storms appear possible from eastern Kansas into
west-central Illinois, over portions of southern Arizona, and from
south-central Colorado into northeast New Mexico Wednesday afternoon
and evening.

...Synopsis...

A broad, cyclonic flow regime will continue from the northern
Rockies into the Great Lakes with an embedded short-wave trough and
associated mid-level jet streak moving through the mid and lower MO
Valley. At the surface, a front will move through the upper Great
Lakes with the western extension of the boundary settling more
slowly south into the mid MS Valley and the southern High Plains.


...Lower Missouri and mid Mississippi Valleys into eastern Kansas...

Thunderstorms are expected to be ongoing at 12Z Wednesday along and
to the north of the surface front from portions of NE and IA into
southern WI and northern IL. Forcing for ascent attendant to the
short-wave trough moving through the region may sustain a subset of
the early-day storms into afternoon. Associated outflow may modulate
the position of the synoptic front with lingering clouds limiting
instability in some areas. Consensus of model guidance indicates the
corridor from eastern KS into west-central IL as being the most
probable location for moderate to strong instability by afternoon.
That area will coincide with the southern fringe of stronger
deep-layer shear oriented largely parallel to the front, suggesting
the potential for at least isolated severe weather during the
afternoon through evening. Only a 5% probability contour has been
included in this forecast due to uncertainties in the specific
location of the effective surface front.  


...Southern Arizona...

Similar to previous days, diurnally enhanced thunderstorms are
expected to form over the Gila Mountains with subsequent
south/southward movement into the lower desert, where a moderately
unstable environment is expected to reside. While deep-layer shear
will remain relatively weak, the presence of a deep, well-mixed
boundary layer will support the potential for isolated severe wind
gusts during the afternoon into evening.


...South-central Colorado into northeast New Mexico...

Isolated storms appear possible Wednesday afternoon into evening
along the Sangre de Cristo Mountains and adjacent Raton Mesa within
a modestly moist, post-frontal upslope regime. The presence of steep
low/mid-level lapse rates and resultant moderate instability will
coincide with 30-40 kt of deep-layer shear, suggesting the potential
for isolated severe weather.

..Mead.. 08/03/2026