Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 161940
SWOMCD
SPC MCD 161940
TXZ000-OKZ000-NMZ000-162145-

Mesoscale Discussion 0437
NWS Storm Prediction Center Norman OK
0240 PM CDT Wed May 16 2018

Areas affected...Portions of the Texas panhandle...western Oklahoma
panhandle...and far northeast New Mexico

Concerning...Severe potential...Watch unlikely

Valid 161940Z - 162145Z

Probability of Watch Issuance...20 percent

SUMMARY...A few thunderstorms capable of severe wind gusts and
severe hail are possible this afternoon and early evening, but
should remain isolated enough to preclude a Severe Thunderstorm
Watch.

DISCUSSION...A small area of thunderstorms developing on the Raton
Mesa is expected to gradually move over the High Plains this
afternoon.  A pocket of 50s to low 60s surface dewpoints reside over
the TX and OK panhandles that has yet to mix out and is supporting
MLCAPE of 1000-2000 J/kg over the area.  Despite some convective
overturning yesterday, mid-level lapse rates are steepening again
under the mean westerly flow aloft.  Although effective bulk shear
is rather weak, stronger upper-level flow in the sub-tropical jet is
helping to produce 35-40 kt of 0-8 km shear.  Furthermore, the 12z
AMA raob, and low-level moisture that is currently higher than
observed there this morning, suggests the area is close to reaching
convective temperatures in the low 80s.  Although HRRR guidance is
not producing convection over the area, the RAP and HRRR background
environments have low-level dewpoints that are 5-10 deg F too low,
which is likely contributing to a lack of forecasted storms in the
area.

The above factors suggest that a storm or two could reach the
unstable air and mature by mid-late afternoon.  While the weak
low-level winds suggest a multicell mode, supercells are possible
since convective updrafts should be able to penetrate the layer with
speed shear in mid-to-upper levels.  Bunkers storm motion is toward
the south to south-southeast, which would allow the storm to move
down the longer axis of the instability over the area.  Severe wind
gusts and severe hail would be the primary threats if this evolution
occurs.  Regardless, the isolated nature of the storm(s) should
preclude the need for a Watch.

..Coniglio/Weiss.. 05/16/2018

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

ATTN...WFO...LUB...AMA...ABQ...

LAT...LON   36890139 36850085 36500051 35900013 35250027 34560075
            34170139 33870176 33940243 34220265 34970286 35450317
            35900329 36460345 36690329 36890287 36960215 36890139




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