Severe Storm Outlook Narrative (AC)
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ACUS03 KWNS 210702
SPC AC 210701

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0201 AM CDT Sat Apr 21 2018

Valid 231200Z - 241200Z


Thunderstorms are possible Monday from the Tennessee Valley through
the Florida Peninsula. Isolated thunderstorms are also possible
across the central High Plains. No severe weather is currently

Mature cyclone likely centered near the MS/AL/TN border intersection
at the beginning of the period is expected to only move slightly
northward throughout the day. Occluded surface low associated with
this cyclone will remain largely in place while a weak triple-point
low drifts eastward across southern AL and into southeastern SC.
Thunderstorms will likely be ongoing at the beginning of the period
along and north of the occluded front between these two lows as well
as along the surface trough extending southwestward from the more
southern low. Convection on the surface trough will likely gradually
weaken as it becomes increasingly displaced from the parent system
amidst only modest instability. Strong low-level flow is possible
across portions of eastern GA and southeastern SC but, given the
anticipated frontal position and moist, weak lapse rate profiles
over the area, any thunderstorms in this region will be likely
elevated and weak.

Farther west, a strong shortwave trough will move slowly from the
northern Rockies into the central Rockies. Progression of this
shortwave (as well as an attendant surface low) will encourage a
southeastward surge of cold air from the northern Rockies/northern
High Plains. Airmass ahead of this front will be relatively dry but
a warm and deeply mixed boundary layer will likely still support
modest destabilization and the potential for isolated thunderstorms
as the cold front moves through.

..Mosier.. 04/21/2018

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