Phoenix, AZ...Denver, CO...Mesa, AZ...Colorado Springs, CO...Aurora, CO...
Probabilistic Tornado Graphic
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 1 Tornado Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 1 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
5 %
358,841
12,996,409
Phoenix, AZ...Denver, CO...Mesa, AZ...Colorado Springs, CO...Aurora, CO...
Probabilistic Large Hail Graphic
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
5 %
58,562
560,925
Missoula, MT...Great Falls, MT...Butte, MT...Helena, MT...Hibbing, MN...
SPC AC 191950
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0250 PM CDT Wed Aug 19 2020
Valid 192000Z - 201200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHEAST
MN...NORTHERN ROCKIES TO SOUTHERN HIGH PLAINS...CENTRAL AZ TO
SOUTHERN CA...
...SUMMARY...
Isolated large hail and damaging winds will be possible across
northeast Minnesota and the northern Rockies into this evening.
Isolated strong to locally severe wind gusts will be possible within
an arc from the central Rockies to the southern High Plains, and
from central Arizona into southern California.
No updates were required to the previous outlook.
..Jewell.. 08/19/2020
.PREV DISCUSSION... /ISSUED 1111 AM CDT Wed Aug 19 2020/
...Northeast MN...
A mid-level impulse across northwest Ontario should track southeast
across northern Lake Superior through this evening. In advance of
this impulse, a west-southwesterly low-level jet segment and
associated warm advection is shifting east from northern MN across
the Upper Great Lakes region. This shift appears to have aided in
the recent decay of elevated convection across northwest and
north-central MN. Convective development should become more
pronounced with time across northwest Ontario with some of this
activity possibly grazing portions of the Arrowhead during the late
afternoon to early evening. Uncertainty exists with the degree of
boundary-layer destabilization in the wake of the ongoing elevated
activity and richer surface moisture still upstream. A risk for
severe hail and damaging winds may become realized over far
northeast MN.
...Northern Rockies to southern High Plains...
Scattered clusters of high-based storms are expected in an arc
from the northern Rockies to the central High Plains during the late
afternoon into this evening, around the northern and eastern
periphery of the persistent Great Basin mid-level anticyclone.
Typical inverted-v thermodynamic profiles will support strong to
locally severe outflow winds. A somewhat greater MLCAPE and
effective shear combination should exist near the northern Rockies,
warranting a risk for isolated severe hail as well. Higher chances
for storms are expected in conjunction with diurnal heating and
embedded speed maxima, across southwestern MT and central ID, and
east of the Front Range in southeast WY and CO.
...Central AZ to southern CA...
The stout mid-level anticyclone over the Great Basin is shifting
gradually southward as height falls occur over the Pacific
Northwest. This has shunted stronger mid-level easterly flow
southward into northwest Mexico, which will limit the potential for
storm clusters to move off the higher terrain and into the lower
deserts. Still, deep inverted-v thermodynamic profiles with at least
scant surface-based buoyancy could support a few microbursts.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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