SPC AC 040558
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Sun Nov 04 2018
Valid 051200Z - 061200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
MISSISSIPPI VALLEY INTO A PORTION OF THE TENNESSEE VALLEY...
Numerous severe storms with potential for damaging wind and
tornadoes are expected Monday evening into the overnight from a
portion of the lower Mississippi Valley into the Tennessee and Ohio
...Lower Mississippi into the Tennessee and Ohio Valleys...
Only minor adjustments have been made to previous outlook, and
guidance remains generally consistent. Potential still exists for
significant severe weather to transpire Monday evening and night,
mainly from the lower MS Valley into the Tennessee Valley regions.
Primary zone of cyclogenesis should commence Monday evening over the
lower MS Valley (northern AR or southern MO) in response to forcing
for ascent in exit region of a progressive, intense upper jet streak
located within base of an amplifying shortwave trough. The cyclone
will deepen as it lifts northeast into the OH Valley Monday night
with trailing cold front advancing through the TN and lower MS
Latest observations indicate surface winds over the western Gulf
have shifted to southerly, and this air continues to modify with
dewpoints already in the low 60s F. Cold front now moving through
east TX as of early Sunday morning will stall along the Gulf coast,
allowing the Gulf boundary layer to modify further through Monday.
Gulf moisture with mid to upper 60s F dewpoints will advect rapidly
northward through the warm sector along a strengthening low level
jet, contributing to destabilization with 500-1500 J/kg MLCAPE by
Monday night, but mid level lapse rates will remain somewhat
marginal. Mixed storm modes including a squall line and supercells
are likely to develop along and just ahead of advancing cold front
by late Monday afternoon, initially over the lower MS Valley, then
continuing east into the TN and OH Valleys overnight. Impressive
wind profiles with large 0-1 km hodographs and intense mid-upper jet
should foster organized storms including embedded bowing segments
and supercells with low-level mesocyclones capable of mainly
damaging wind and tornadoes, though some hail will also be possible.
A moderate risk upgrade might be warranted for a portion of this
region in later outlooks.
...MAXIMUM RISK BY HAZARD...
Tornado: 10% SIG - Enhanced
Wind: 30% SIG - Enhanced
Hail: 15% - Slight
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