SPC MD 1487



MD 1487 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR PORTIONS OF FAR EASTERN SD…SOUTHWEST INTO CENTRAL MN…NORTHWEST IA AND FAR NORTHEAST NE

MD 1487 Image


Mesoscale Discussion 1487
NWS Storm Prediction Center Norman OK
0157 PM CDT Fri Aug 14 2020

Areas affected...portions of far eastern SD...southwest into central
MN...northwest IA and far northeast NE

Concerning...Severe potential...Watch likely 

Valid 141857Z - 142100Z

Probability of Watch Issuance...95 percent

SUMMARY...The severe threat is increasing across the MCD area. One
or more watches will be needed in the next 1-2 hours.

DISCUSSION...A surface low is currently located over far northeast
SD with a cold front trailing south/southwest across far eastern SD
into northeast and central NE. Deepening CU has been noted in
visible satellite imagery over the past hour and convective
initiation appears likely to occur soon near the NE/SD border. Ahead
of the front, temperatures have warmed into the low to mid 80s F
with dewpoints generally from the mid 60s to low 70s F. An outflow
boundary produced by overnight convection resides across central MN.
While some airmass recovery has been made in the vicinity of the
boundary, surface dewpoints remain in the lower 60s. Nevertheless,
moderate to strong instability is present over the region, aided
further by steep midlevel lapse rates. Temperatures are quickly
approaching convective temp per modified RAP forecast soundings and
remaining weak inhibition should be overcome with increasing ascent
and continues warm advection. Effective shear around 30-40 kt will
support organized convection, with main storm mode expected to be
clusters/line segments given linear forcing along the front.
Damaging wind gusts and hail will be the primary threat with this
activity. 

Additionally, any more discrete cells along the front or that may
develop ahead of the main line will experience strong SRH where
backed low level winds closer to the surface low and near/south of
the outflow boundary exist. 18z mesoanalysis also indicates STP
values around 2-5. As such, a couple of tornadoes also appear
possible. Given this tornado potential, one ore more watches may be
needed to cover both the broader severe wind/hail threat in addition
to the tornado threat.

..Leitman/Grams.. 08/14/2020

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DLH...MPX...DMX...FGF...FSD...OAX...ABR...

LAT...LON   41879477 41609549 41699623 42059681 42499720 42879730
            43739695 44579689 46289714 46609647 46709545 46529441
            46089397 45469338 44989336 44619326 44309331 43779342
            42849386 42099444 41879477 

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