Severe Storm Outlook Narrative (AC)
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

735
ACUS11 KWNS 220012
SWOMCD
SPC MCD 220011
ARZ000-TXZ000-OKZ000-220145-

Mesoscale Discussion 0541
NWS Storm Prediction Center Norman OK
0711 PM CDT Fri Apr 21 2017

Areas affected...Portions of southeast Oklahoma...North Texas,

Concerning...Tornado Watch 155...

Valid 220011Z - 220145Z

The severe weather threat for Tornado Watch 155 continues.

SUMMARY...The threat for large hail, damaging winds and a few
tornadoes continues across the watch area.

DISCUSSION...Semi-discrete supercell storms were located in the
vicinity of a nearly stationary composite frontal boundary over
southeast OK at 00z. With effective shear ranging from 45-50 kts and
0-1 km SRH in the 150-250 m2/s2 range, the environment over
southeast OK will remain supportive of supercells with all severe
hazards possible over the next few hours given moderate
surface-based instability. An increasing low-level jet this evening
will further augment low-level SRH and support a continued risk for
low-level rotation and a couple tornadoes. Increasing storm coverage
is expected with time as low-level warm advection increases this
evening.

Farther west and south, a few storms were located near, and slightly
behind, a cold front that extended across northwest TX generally
southwest into the TX South Plains. The 00Z Fort Worth sounding
revealed low-level veering but also relatively higher LCL heights
and some remaining CINH.  As the evening progresses additional
thunderstorm development is expected along the cold front as frontal
lift overcomes CINH, possibly as far west as a dryline intersection
with the front in the vicinity of Abilene TX. In the presence of
moderate surface-based instability and 45-50 kts of deep-layer
shear, a few supercells with damaging winds and large hail are
expected. Latest RAP-based forecast soundings suggest a modest
increase in low-level SRH this evening along with lowering LCL
heights due to slow nocturnal cooling.  This would result in at
least an isolated tornado threat.

..Bunting.. 04/22/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

LAT...LON   33709775 34669694 35129640 35209575 35259517 35269470
            35279438 35229392 35179357 35039337 34849328 33959357
            33139400 32519435 32289498 32129577 31899670 31769744
            31829781 31979850 32399868 33709775




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.