NOAA Storm Prediction Center

Convective Outlooks

Convective Outlooks
The convective outlooks serve as guidance to the local NWS forecast offices and are used by emergency managers, private sector meteorologists, media, and other weather customers concerned with public safety. Three separate risk areas (slight, moderate, and high) are used to describe the expected coverage and intensity for the categorical severe weather threat on days 1-3 along with severe weather probabilities for the potential threat.

Day 1 Outlook Day 2 Outlook Day 3 Outlook Days 4-8 Outlook

Day 1 Outlook Convective Tornado
Hail Wind
Categorical Day1 1300Z Outlook
  
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 Forecast Discussion


000
ACUS01 KWNS 241302
SWODY1
SPC AC 241300

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0800 AM CDT Thu May 24 2018

Valid 241300Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Isolated to scattered strong to severe thunderstorms are expected
across the Great Plains and upper Mississippi Valley this afternoon
and evening.

...Northern Plains and Upper Mississippi River Valley...
An upper low over eastern Montana this morning will continue
northeastward toward Saskatchewan and Manitoba today with height
falls occurring eastward into the Upper Mississippi Valley while
southwesterly mid-level winds modestly increase over the eastern
Dakotas into Minnesota. In the wake of widely scattered early-day
precipitation and diminishing cloud cover, ample heating coincident
with prevalent low/some middle 60s F surface dewpoints will support
moderate destabilization (1500-3000 J/kg MLCAPE) ahead of an
eastward-advancing front.

A weak impulse/MCV over eastern South Dakota may help focus
thunderstorm development/intensification across Minnesota this
afternoon, although downstream clouds may linger and parts of the
Upper Mississippi Valley will reside to the east of the steeper
lapse rates/stronger winds aloft. Additional at least widely
scattered development can be expected across the Dakotas near the
wind shift/front. Although relatively strong high-level flow will
exist across the region, weak low-to-mid tropospheric winds will
largely limit effective shear magnitudes to 30 kt or less in most
areas. Overall, mostly multicellular storms are expected with the
potential for a few sub-regional corridors of damaging winds and
hail to evolve mainly this afternoon and evening.

...Central Plains...
In the wake of lingering early-day cloud cover related to weakening
convection and an MCV or two, the air mass should moderately
destabilize this afternoon near/east of a surface trough on the
eastern edge of a High Plains elevated mixed layer. Initial
thunderstorm development and intensification will mostly likely
occur near the surface trough and just north of a weak surface low
where weak convergence and modest upslope trajectories will exist.
This would include portions of far western Kansas and east-central
Colorado where moderate instability and 35 kt of effective shear
could support a spatiotemporal window this afternoon for some
marginal supercell structures capable of hail.

These storms are likely to subsequently increase in coverage and
spread eastward into an increasingly unstable boundary layer but
weaker shear environment across western/central Kansas, with some
additional development/expansion into Nebraska possible. A
nocturnally increasing low-level jet could support a small-scale MCS
or two capable of wind damage before storms diminish in intensity by
late evening and overnight.

...Southern High Plains...
While likely to see less storms than prior days as an upper ridge
builds across the region, at least isolated diurnally maximized
thunderstorm development should again occur this afternoon across
southeast New Mexico into a broad part of west/northwest/southwest
Texas with aid of factors such as weak upslope and differential
heating. While weak low to mid tropospheric winds will only support
25-30 kt of effective shear (maximized across southwest Texas),
steep lapse rates and moderate quantities of moisture and buoyancy
could yield some storms capable of episodic severe hail and
severe-caliber wind gusts through the afternoon and evening.

...Western Nevada vicinity...
It appears that a semi-focused corridor of thunderstorm development
could occur this afternoon into evening as stronger forcing for
ascent arrives into the region related to the closed low approaching
the California coast. While deep-layer winds will not be overly
strong, sufficient moisture and steep lapse rates could support some
stronger/semi-organized north/northeastward-moving storms mainly
late this afternoon into evening. Severe-caliber wind gusts and some
hail could occur on a localized basis.

..Guyer/Goss.. 05/24/2018

$$