Severe Storm Outlook Narrative (AC)
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000
ACUS01 KWNS 241237
SWODY1
SPC AC 241235

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Sun Sep 24 2017

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS MN...

...SUMMARY...
Isolated damaging winds and a brief tornado are possible in
Minnesota from 3 to 8 pm CDT.

...MN...
Maintained a Marginal risk.

Consensus of guidance suggests a weak cyclone over south-central NE
will track northeast along a quasi-stationary front into
west-central MN by evening. Robust diabatic heating is anticipated
over much of central and southern MN amid 60-65 F surface dew
points. While poor 700-500 mb lapse rates around 5 C/km will hinder
buoyancy and updraft acceleration, the presence of 40-50 kt 700-mb
south-southwesterlies along the frontal zone suggest that a few
rotating updrafts should evolve with northeast-moving clusters and
short-line segments in the late afternoon to early evening. Storms
will weaken after sunset owing to the weak instability aloft and
nocturnal boundary-layer stabilization.

...Trans-Pecos to the Raton Mesa...
Considered a Marginal risk for hail over the Trans-Pecos and the
Raton Mesa vicinity.

In the wake of a meridional stratiform convective band over the
central/southern High Plains, upper 50s to lower 60s surface dew
points remains common. Isolated storms should develop over the
higher terrain of the Trans-Pecos by late afternoon and persist into
the evening. Farther north across eastern NM, guidance strongly
suggests that convective redevelopment will be delayed until tonight
as low-level upslope flow increases. Mid to upper-level speed shear
in both regions should be adequate for a couple weakly rotating
updrafts. However, weak mid-level lapse rates sampled by 12Z
Albuquerque and El Paso soundings suggest the probability of severe
hail is too low to warrant a risk area.

..Grams/Jewell.. 09/24/2017

$$


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