Day 1 Severe Weather Outlook

Valid 150100Z – 151200Z


Isolated to scattered severe wind gusts are possible the remainder
of the evening across southern and central Arizona. Isolated severe
storms with large hail and damaging wind gusts are possible from the
Upper Midwest to the central Great Plains through tonight.

…01z Update…

The Marginal risk area has been removed from the Appalachians as
convection has diminished with loss of daytime heating. A few
storms will linger another 1-2 hours, but severe threat is expected
to be low the remainder of the evening.

The Marginal risk area across the Upper Midwest has been modified
based on latest hi-res guidance trends and surface observations. The
biggest change was to trim some of the area across central MN into
northern WI. Thunderstorms from earlier this afternoon have largely
weakened, and additional convection forming that far north overnight
does not appear likely. Latest hi-res guidance has trended toward
additional development later this evening/overnight ahead of a weak
surface boundary/low as the low level jet increases and stronger
warm advection shifts east from southern WI into northern IL. Expect
that a line/cluster of storms will develop western/central IL and
shift east into southern WI/northern IL, posing mainly a threat for
marginal hail and possibly some strong gusts. Given latest trends,
have expanded the Marginal risk on the southern end across southern
IA/northern IL.

Thunderstorms continue to shift westward off of higher terrain
across central AZ. Strong gusts will continue to be possible with
this activity for several more hours this evening. The severe threat
should diminish after 06z as convection approaches the Lower CO

..Leitman.. 09/15/2019


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