SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0255 PM CDT Wed Apr 07 2021

Valid 072000Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
OF ARKANSAS...NORTHERN LOUISIANA...CENTRAL AND NORTHERN
MISSISSIPPI...AND SOUTHWEST TENNESSEE...

...SUMMARY...
Scattered severe thunderstorms are expected from this afternoon into
the evening across parts of the lower Mississippi Valley, Mid-South,
Arklatex and Ozarks.  Wind damage, hail and tornadoes will be
possible.

...Discussion...
The forecast appears on track. Strong to severe storms have
developed along and ahead of the cold front from northern Missouri
to east Texas. Large hail, damaging winds and tornadoes remain the
primary threat which is expected to continue through the afternoon
and into the evening hours.

..Bentley/Dial.. 04/07/2021

.PREV DISCUSSION... /ISSUED 1105 AM CDT Wed Apr 07 2021/

...Lower MS Valley...
An upper low is evident this morning over central KS, with a
shortwave trough rotating through the base of the low into parts of
OK/TX.  Strong forcing for ascent ahead of this trough will
overspread a cold front currently over eastern OK, leading to
thunderstorm development by early afternoon.  Abundant clouds have
limited daytime heating ahead of the front over parts of AR/LA, but
dewpoints in the 60s and rather steep lapse rates will yield
afternoon MLCAPE values of 1500+ J/kg.  South-southwesterly
low-level winds of 40+ knots will result in favorable vertical shear
profiles (0-3km SRH values of 150-300 m2/s2) for supercell storms
capable of large hail, damaging winds, and tornadoes.  Messy storm
modes are likely to evolve through the afternoon, but a continued
risk of damaging winds and tornadoes will persist into parts of west
TN and much of MS before storms move out of primary
moisture/instability axis this evening.

...Mid MS Valley...
A surface low is currently analyzed over eastern KS, with a cold
front extending southeastward into western MO.  An area of
precipitation has affected much of MO during the morning, but is
moving away and allowing some air mass recovery.  Present
indications are that scattered thunderstorms will form early this
afternoon along the front and move across much of MO before
weakening as they track into more stable air over IL this evening. 
The strongest cells will be capable of hail, damaging winds, and
isolated tornadoes.  Please refer to recent MCD #321 for further
details.

...MN/WI...
Most 12z CAM solutions suggest the development of a cluster of
thunderstorms this afternoon over parts of eastern MN/western WI. 
This would be in vicinity of a retreating warm front, where broken
cloudiness and dewpoints in the 50s will result in MLCAPE values
around 1000 J/kg.  A strong storm or two is possible for a few hours
this afternoon, capable mainly of hail.

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