MD 1707 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF NORTHERN/CENTRAL TX
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
from SPC Mesoscale Discussions http://bit.ly/2kyGONe
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