- Täna
- Homme
- Day Three
000
acus01 kwns 200509
swody1
Storm Prediction Center ac 200507
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
1207 am CDT Wed Sep 20 2017
Valid 201200z - 211200z
..there is a marginal risk of severe thunderstorms from Upper
Michigan southwestward into northeast Kansas...
...
A few strong storms are possible from northeastern Kansas
northeastward to the Upper Peninsula of Michigan this afternoon and
evening.
..synopsis and discussion...
A potent shortwave trough will quickly exit the northern
plains/upper MS valley in a negatively tilted fashion with an
occluded front moving from northern Minnesota into western Ontario. To the
south, a weak boundary will remain, extending from WI into eastern
Kansas. To the east of this front, a moist and unstable air mass will
exist with upper 60s dewpoints.
Scattered storms are likely to develop during the afternoon along
this front, especially over northern areas including WI, eastern IA,
and the u.P. Of Michigan where convergence is strongest. However, forcing
for ascent will generally be weak as the primary shortwave trough
continues away from the region. Capping will be a concern for much
of the day, with only a narrow zone of storms expected near the
front. Marginally severe hail and wind are most likely, and a
brief/weak tornado cannot be ruled out given a moist boundary layer
and modest low-level shear.
.Jewell.. 09/20/2017
$$
Mesoscale Discussion
000
acus11 kwns 200604
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 200603
mnz000-200730-
Mesoscale discussion 1661
National Weather Service Storm Prediction Center Norman OK
0103 am CDT Wed Sep 20 2017
Areas affected...Minnesota
Concerning...Severe Thunderstorm Watch 488...
Valid 200603z - 200730z
The severe weather threat for Severe Thunderstorm Watch 488
continues.
Summary...the ongoing line of storms probably will tend to weaken
diminish as it progresses east of watch 488, but it is still
possible that another watch will be needed to account for a
lingering risk of potentially damaging wind gusts.
Discussion...the more vigorous southern flank of the pre-cold
frontal squall line is progressing east northeastward around 40 kt,
and appears likely to progress east of the watch into east central
portions of Minnesota (including the Minneapolis/St. Paul Metro
area) during the 07-09z time frame. However, even within the narrow
corridor of higher pre-frontal surface dew points (mid 60s),
forecast soundings suggest that activity is likely rooted above a
fairly deep (1-1.5+ km) surface based stable layer, supported by
low-level warm advection. While the stronger mid/upper forcing for
large-scale ascent pivots northward into the international border
area, and inflow of drier more stable air becomes an increasing
issue with eastward extent, general weakening trends seem probable
within the next few hours. Even now, it is not particularly clear
that the risk of strong downdrafts reaching the surface is
particularly high, but until more substantive weakening of
convection begins, heavy precipitation could continue to aid at
least the downward Transfer of higher momentum to the surface,
accompanied by localized potentially damaging wind gusts.
.Kerr.. 09/20/2017
..please see www.Spc.NOAA.Gov for graphic product...
Attention...WFO...dlh...mpx...fsd...
Latitude...Lon 45499468 46269454 46209348 45339305 44129320 43539442
43619518 44469484 45499468
