Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 211627
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1127 AM CDT Tue Mar 21 2017
Valid 211630Z - 221200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PARTS OF TENNESSEE...NORTHERN ALABAMA...AND NORTH
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
MISSOURI INTO WESTERN SOUTH CAROLINA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN AR
INTO THE CAROLINAS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE PARTS
OF THE SACRAMENTO VALLEY OF NORTHERN CALIFORNIA...
Hail and damaging thunderstorm gusts are possible today from the
Ozarks across the Tennessee Valley to the southern Appalachians. An
enhanced corridor of severe threat is expected this afternoon and
evening from middle Tennessee to northeastern Alabama and northern
Georgia. An isolated severe storm or two, capable of hail, damaging
gusts and/or a tornado, may develop also across portions of the
California Central Valley.
...Mid MS Valley to the Southeast States...
The morning surface analysis shows a weak frontal boundary extending
from a low over OK into northern AR and TN. A cluster of
thunderstorms has developed this morning near the front over
southwest MO, where isolated severe hail has occurred. These storms
have weakened somewhat in the short-term, but are expected to
intensify again this afternoon as strong daytime heating
destabilizes the air mass over northeast AR and west TN. 12z model
guidance is very consistent in depicting these storms organizing
into an MCS that tracks east-southeastward across much of TN,
northern AL and eventually into northern GA. Forecast soundings
along this corridor show favorable parameters for large hail, and
increasing mesoscale organization will likely enhance the risk of
damaging winds later today. Therefore will maintain the ENH risk
area. The storms are expected to weaken after sunset over SC.
Scattered thunderstorms are expected this afternoon and evening over
the Sacramento Valley of northern CA. It is unclear how much
destabilization will occur in this region, as clouds and showers are
prevalent at this time. However, forecast soundings suggest
favorable vertical shear profiles and mid level lapse rates will be
present. This will result in a risk of a few strong cells capable
of hail, damaging winds, and/or a tornado or two. Some low risk of
severe storms extends northeastward into parts of northern NV,
eastern OR, and southern ID as well. However, will not extend MRGL
risk into these areas due to cloud cover and limited instability.
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