SPC MD 571


MD 0571 Image

Mesoscale Discussion 0571
NWS Storm Prediction Center Norman OK
0222 PM CDT Tue May 07 2019

Areas affected...Portions of west Texas

Concerning...Severe potential...Tornado Watch likely 

Valid 071922Z - 072045Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorms are expected to develop in the next 1-2
hours.  A Tornado Watch is likely.

DISCUSSION...Cumulus is developing to the east of a slowly-advancing
dryline aided by forcing for ascent in the left exit region of an
approaching upper jet.  Modifying RAP short-term forecast soundings
for current surface conditions suggests most of the MLCIN has eroded
over the area with 2000-3000 J/kg of MLCAPE.  Therefore, despite
some tempering of the surface heating from a thin layer of cirrus
overspreading the area, widely-scattered to scattered thunderstorms
are expected to develop in the next hour.

Although deep-layer shear has been marginal for supercells (25-35
kt) through early afternoon, it has increased to 35-45 kt the last
hour with the strengthening mid-upper flow.  Given the
moderate-to-strong instability and steep mid-level lapse rates,
thunderstorms should become severe rather quickly, with supercell
modes dominant initially.  Somewhat veered low-level near-surface
winds in the 10-15 kt range is limiting low-level shear, and the
tornado potential, at the moment.  Further limited tornado potential
is some weakness in the 850-700 mb flow seen in forecast soundings
through early evening.  However, temperature-dewpoint spreads
holding in the 12-16 deg C range and strengthening/backing 500-1000
m AGL winds in the next few hours should increase the tornado threat
somewhat by 21-22z.  A Tornado Watch will likely be needed in the
next 1-2 hours.

..Coniglio/Guyer.. 05/07/2019

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


LAT...LON   33370098 32950125 32650179 32580253 32680291 33140301
            33630293 34100293 34240291 34500284 34650259 34700179
            34710151 34540115 34150102 33370098 

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