Day 1 Severe Weather Outlook

Valid 012000Z – 021200Z


Isolated strong to severe storms are expected through this evening
from parts of the Great Plains into the Mid Missouri Valley and
Great Lakes.

…NE/KS to Lake Michigan Vicinity…

The latest trends from RAP and HRRR guidance indicate a narrow
corridor of relatively greater tornado potential exists from far
northeast KS/southeast NE into southern/central IA and far northwest
MO through this evening. Currently, a pre-frontal trough extends
from central KS to near AFK in southeast NE and then northeast
toward DSM in IA. The 18z RAP develops a weak surface low tracking
northeast along this path over the next several hours. As a result,
southwesterly surface winds are forecast to back to a more southerly
direction along this narrow corridor. In fact, latest surface
observations show southerly winds at FNB in extreme southeast NE and
southeasterly surface winds at SDA in Fremont county in IA. Backed
low level flow will act to enhance low level hodographs and SRH. Any
discrete cells ahead of the cold front could take advantage of
improving low level shear and a few tornadoes are possible over the
next several hours into this evening. As such, a small 5% tornado
probability area has been included with this update. The Slight risk
area also has been adjusted modestly across northeast KS into
northern MO to account for latest trends in hi-res guidance.

Elsewhere, the previous outlook remains on track and no other
changes have been made other than to adjust the 10% general thunder
line based on latest model guidance.

..Leitman.. 10/01/2019

.PREV DISCUSSION… /ISSUED 1114 AM CDT Tue Oct 01 2019/

…WI to MI…
A large upper ridge is centered over the central/southern MS Valley
today, with relatively strong midlevel winds extending from west TX
into IA/WI and eastward into MI/NY/VT. This axis is where the
surface baroclinic zone lies, and will be the focus for organized
thunderstorm development today and tonight.

Once cluster of storms is currently over WI and Lower MI. Heating
is occurring along the southern flank of this activity, where
sufficient destabilization will result in surface-based storms by
mid-afternoon. Forecast soundings show sufficient westerly flow
aloft for a risk of a few damaging wind gusts in the strongest
cells. Please refer to MCD #2046 for more details.

…TX to IA…
A large but weakening MCS over the TX Panhandle will likely track
into northwest OK and central KS this afternoon, where MLCAPE values
around 1000 J/kg will develop. Midlevel lapse rates are forecast to
be weak, limiting updraft intensity and hail threat. However,
strong winds aloft and sufficient vertical shear will pose a risk of
bowing/rotating cells capable of damaging winds and a tornado or two
from central KS into parts of northwest MO and IA.

Strong heating is occurring today over parts of southern Ontario,
where sufficient CAPE will result in scattered afternoon
thunderstorms. These storms will track eastward into parts of
northern NY and VT. Forecast soundings show strong winds aloft and
perhaps enough thermodynamic support for a few strong/severe storms
capable of damaging wind gusts. However, broken cloud cover and
dewpoints only in the 50s to lower 60s in much of the region will
likely limit the extent of the threat today.


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