RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Tue Jun 16 06:46:01 UTC 2026.
No Mesoscale Discussions are in effect as of Tue Jun 16 06:46:01 UTC 2026.
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Tue Jun 16 2026
Valid 161200Z - 171200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY THROUGH
TONIGHT ACROSS PARTS OF THE NORTHERN GREAT PLAINS INTO MIDWEST AND
NEAR THE GULF COAST...
...SUMMARY...
Areas of mainly widely scattered strong thunderstorm development,
accompanied by at least some risk for severe weather, are possible
across parts of the northern Great Plains into Midwest and near the
Gulf Coast vicinity today through tonight.
...Discussion...
Higher latitude blocking appears likely to maintain a broad area of
cyclonic mid-level flow with anomalously low heights to the lee of
the northern Rockies through the northern and middle Atlantic
Seaboard. Within this regime, models suggest that an initially
vigorous short wave trough (now digging into the Upper Midwest) may
maintain strength into and across the Lake Michigan vicinity, before
undergoing considerable deformation while turning eastward and
northeastward, to the southeast of a mid-level becoming centered
near the northern Manitoba/northwestern Ontario border. After
rounding the crest of mid-level ridging centered over the northern
mid-latitude eastern Pacific, it appears that another significant
short wave perturbation will dig through the broadly confluent
regime to the southwest of the low, across the northern Rockies
through northern Great Plains by late tonight.
In lower latitudes, mid/upper ridging emanating from the subtropical
Atlantic may maintain considerable influence across the Florida
peninsula today, while weak troughing, perhaps with a developing
mid-level cyclonic circulation, slowly pivots across the lower Texas
and Mexican Gulf coast.
In lower levels, seasonably high boundary-layer moisture content has
generally been maintained across much of the Gulf coastal plain. It
appears that strengthening southerly low-level flow may support more
substantive moisture return to the southeast of deepening surface
troughing across the northern into central Great Plains by late
tonight.
...Midwest/Great Lakes...
Weak convection accompanying forcing for ascent associated with the
lead short wave trough appears likely to persist and perhaps
increase across the Upper Midwest through Great Lakes and Ohio
Valley during the day. Coinciding low-level cooling is likely to at
least slow, if not inhibit, boundary layer warming in the wake of
this activity. However, various model output suggests that
associated low-level moistening, coupled with a period of insolation
beneath a developing mid-level dry slot, may be sufficient to
support a corridor of modest destabilization as the mid-level cold
pool (including 500 mb temperatures around -18 to -20C) overspreads
the southern Lake Michigan vicinity late this afternoon. This
environment might become sufficient for a developing broken band of
vigorous convection, perhaps including supercells, posing a risk for
severe hail/wind and possibly a tornado or two, before weakening
later this evening.
...Central Great Plains...
Forcing for ascent to support convective development along the
stalling cold front, trailing the short wave trough progressing into
the Great Lakes/Ohio Valley, remains unclear. However, there
appears a general consensus within model output that boundary-layer
moistening may support CAPE on the order of 1000-2000 J/kg across
parts of southern Kansas into southwestern Missouri, where mid-level
inhibition may remain weak enough through late afternoon/early
evening to allow for isolated/widely scattered thunderstorm
initiation. If this occurs, guidance indicates sufficient shear for
supercell development, before increasing inhibition suppresses
convection later this evening.
...Gulf Coast...
Models indicate modest strengthening of westerly flow (including
20-40 kt in the 850-500 mb layer) in a belt across the north central
through northeastern Gulf coast vicinity today. Coinciding with
destabilization driven by daytime heating of the seasonably moist
boundary layer, this may support modestly organizing convection,
perhaps transient supercell structures, posing a risk for damaging
wind gusts and perhaps an isolated tornado or two.
...Northern Great Plains into Midwest...
Models suggest that a corridor of fairly deep boundary-layer mixing
will precede the vigorous short wave trough digging across and
east-southeast of the Canadian/northern U.S. Rockies. It appears
that associated mid-level forcing for ascent will contribute to
sufficient destabilization to support scattered thunderstorm
development with potential to produce some hail and scattered strong
to severe surface gusts late this afternoon into evening.
Within strengthening downstream warm advection, forcing for ascent
may begin to interact with better elevated moisture return to
support increasing strong thunderstorm development with potential to
producing severe hail by late tonight, across parts of eastern Iowa
and adjacent portions of the Midwest.
..Kerr/Weinman.. 06/16/2026
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Tue Jun 16 2026
Valid 171200Z - 181200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL ILLINOIS INTO NORTHWEST INDIANA...
...SUMMARY...
An outbreak of severe thunderstorms is expected across portions of
Illinois and Indiana on Wednesday. Intense tornadoes, swaths of
damaging gusts to 80 mph and hail to 2.5 inch diameter are expected.
...Midwest...
A volatile environment for severe thunderstorms is expected to
develop across portions of the Midwest from IA/MO into IL/IN/OH on
Wednesday, with significant all-hazards severe expected.
A mid/upper level shortwave trough initially over the northern
Plains early Wednesday will pivot southeast across the Upper Midwest
through 00z, and much of the Great Lakes by 12z Thursday. As this
occurs, particularly intense mid and upper level flow, especially by
June standards, if forecast to increase over the region. A 60-80 kt
westerly 500 mb jet stream will overspread much of the Midwest
through the evening, before increasing further during the nighttime
hours. Furthermore, an impressive southwesterly 850 mb low-level jet
around 50-60 kt will be oriented from KS into IA at 12z. This
feature will spread east/northeast across IL/IN/OH through evening.
Interestingly, the core of the low-level jet may be somewhat
displaced to the east of the core warm sector expected to develop
across the Mid-MS Valley vicinity, perhaps tied to an early-day
shortwave impulse ejecting across IA/IL during the morning.
Nevertheless, 40-55 kt 850 mb winds will persist even across the
warm sector even as the core of the low-level jet overspreads the
Ohio Valley toward Lower MI during the afternoon.
At the surface, an elongated area of low pressure will extend from
ND to the Mid-MO valley Wednesday morning. A warm front will extend
from northwest IA southeastward across central IL, while a cold
front extend from eastern NE into western KS. As this system
progresses east through the day, the warm front will lift northward
into northern IL/IN/OH and upper 60s/near 70 dewpoints are expected.
Aided by steep midlevel lapse rates/cooling aloft, MLCAPE will
approach 2500-3500 J/kg. The latitude of the warm front continues to
be a point of uncertainty. Most forecast guidance depicts morning
convection near and north of the warm front within a strong warm
advection regime moving eastward across IA/northern IL/IN. It is
uncertain if this will suppress the northward advancement of the
warm front. The ultimate position of the warm front will have large
impacts on where particularly concerning strong to intense tornado
potential may eventually develop as storm motion would likely be
along the boundary, rather than across the boundary, allowing for
potentially fast-moving/long-track supercells interacting with the
warm front and remaining within the favorable warm sector.
As the surface cold front develops east, additional convection will
develop along the boundary by late afternoon/early evening from far
southeast IA into northern MO and eastern KS. Initial supercells
along this boundary will pose an all hazards risk -- including very
large hail, strong tornadoes and damaging gusts. With time, this
convection may develop into a line propagating east/southeast. If a
linear MCS develops, swaths of damaging wind gusts will be possible.
In general, given the strength of background flow fields, damaging
wind potential could be significant regardless of storm mode.
Furthermore, even storms developing north of the warm front could
still produce severe gusts given large MUCAPE, fast storm motion and
intense flow just above the surface. Favorable low-level shear will
also support continued tornado potential even within a linear storm
mode via embedded supercell structures and mesovortex generation.
Large to very large hail potential is most likely early in storm
development and where supercells are more likely to remain discrete
(northern MO/far southeast IA/north-central IL).
...Gulf Coast...
Isolated strong gusts are possible in association with a tropical
disturbance moving eastward along the Gulf Coast. See the tropical
weather outlook from the National Hurricane Center for more
information.
..Leitman.. 06/16/2026
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