Severe Storm Outlook Narrative (AC)
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ACUS01 KWNS 171933
SWODY1
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 THUNDERSTORM AREAS FORECAST...

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

...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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