Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS11 KWNS 211255
SPC MCD 211254
Mesoscale Discussion 0534
NWS Storm Prediction Center Norman OK
0754 AM CDT Fri Apr 21 2017
Areas affected...Western and central OK
Concerning...Severe Thunderstorm Watch 153...
Valid 211254Z - 211500Z
The severe weather threat for Severe Thunderstorm Watch 153
SUMMARY...Potential exists for an increasing risk for damaging winds
across western into central Oklahoma this morning. Prior to the
line of storms moving into central OK later this morning, hail will
remain the primary threat with the cluster of ongoing storms.
DISCUSSION...12Z surface analysis indicated relatively strong
pressure rises centered on Gage, OK with a 4.5 mb pressure rise in 2
hours, while 2-3 mb pressure falls persisted across central OK.
Trends in mosaic radar imagery showed a band of storms, extending
from Alfalfa County OK to Beckham County OK had increased its
forward speed to around 40 kt. A continuation of surface pressure
rises behind this line should aid in sustaining the forward speed,
with the potential for an increasing threat for damaging winds.
Current track of this band suggests damaging winds should reach the
OKC metro area between 14-15Z.
Meanwhile, isolated severe hail will remain a primary threat with
ongoing elevated storms centered over the OKC metro area. 12Z
surface analysis indicated these storms were located well north of a
stationary boundary extending generally east to west across extreme
southern OK near the Red River. A 40-50 kt southerly low-level jet
is sustaining sufficient low-level warm advection north of this
boundary. This combined with MUCAPE of 1000-1500 J/kg, 40-50 kt of
effective bulk shear, and steep midlevel lapse rates favor the hail
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 35120005 35929891 36839833 36989782 36999673 36449656
35119646 34679648 34379670 34079709 34159781 34519878
34419926 34499994 34810037 35120005