Severe Storm Outlook Narrative (AC)
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ACUS01 KWNS 171933
SPC AC 171932

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0132 PM CST Sun Dec 17 2017

Valid 172000Z - 181200Z


No severe thunderstorms are expected across the U.S. through

...Western through central Gulf Coast region...

Primary change to previous outlook has been to remove the marginal
risk area. A few thunderstorms will persist next few hours over the
central Gulf Coast region. A small moist warm sector has advected
inland from southwest AL into the western FL panhandle with upper
60s F dewpoints, but widespread clouds have limited boundary layer
destabilization, resulting in a shallow near-surface stable layer.
Moreover, mid-level lapse rates are very weak limiting MUCAPE to
below 500 J/kg. The very marginal thermodynamic environment and
tendency for low-level winds to veer and weaken as primary low-level
jet shifts east of warm sector in association with a deamplifying
shortwave trough suggest overall severe threat should remain less
than 5% the rest of this period.

..Dial.. 12/17/2017

.PREV DISCUSSION... /ISSUED 1020 AM CST Sun Dec 17 2017/

...Southeast Louisiana and nearby Gulf Coast...
In the wake of a weakening shortwave trough over the Midwest, the
region will be increasingly influenced by gradually rising
heights/NVA the remainder of the day. A composite band of
convection, which includes a few embedded thunderstorms, extends
from southwest AL southwestward into far southeast MS and coastal
southeast LA late this morning.

The east-northeastward movement of this convection will generally
tend to outpace inland moistening and destabilization with a richer
maritime air mass remaining offshore. This scenario, along with a
continued weakening and veering of 2-3 km AGL winds, should
considerably limit today`s severe potential, although a few strong
storms will nonetheless remain possible this afternoon immediately
near the coast.

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