SPC MD 1707

MD 1707 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF NORTHERN/CENTRAL TX

MD 1707 Image


Mesoscale Discussion 1707
NWS Storm Prediction Center Norman OK
0454 PM CDT Mon Oct 09 2017

Areas affected...Portions of northern/central TX

Concerning...Severe potential...Watch unlikely 

Valid 092154Z - 100030Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated to widely scattered thunderstorms should develop
late this afternoon and pose a very isolated risk for damaging winds
and hail into the evening. Watch issuance is not expected.

DISCUSSION...Low-level convergence along a southeastward-moving cold
front will likely provide a sufficient source of lift to initiate
isolated to widely scattered thunderstorms over the next several
hours across parts of northern/central TX. Recent visible satellite
imagery indicates convection is attempting to form along the length
of the front, but is still struggling to reach the LFC as of 2150Z,
possibly due to a weak residual inversion at the top of the boundary
layer present on the 12Z FTW sounding. Regardless, moderately to
locally strong instability has developed this afternoon ahead of the
front owing to strong diurnal heating and a moist low-level airmass.
Stronger mid-level flow lags to the west and northwest the front,
which is limiting effective bulk shear values to no more than 25-30
kt immediately along and just behind the front. This marginal shear
will likely preclude more robust updraft organization even with the
favorable thermodynamic environment. Still, steep low-level lapse
rates may encourage strong to perhaps damaging convective downdraft
winds within any thunderstorms that can form along the front, and
some marginally severe hail could also occur with initially discrete
development. This marginal/isolated severe threat should diminish by
mid-evening with the loss of daytime heating and related
instability.

..Gleason/Hart.. 10/09/2017

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

ATTN...WFO...FWD...EWX...SJT...

LAT...LON   31679922 31979850 32389788 33249723 33659715 33679636
            33619590 33159590 32579597 31409724 30949802 30749898
            31189950 31419952 31679922 

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