Alert archive / Texas / Mesoscale Discussions in 2018

Mesoscale Discussion 71

February 18, 20186 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Feb 18, 2018, 3:47 PM CST for 6 counties in Texas. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Feb 18, 2018, 3:47 PM CST (21:47 UTC)
Expired: Feb 18, 2018, 4:45 PM CST
In force: 58 min
Issued by: the Storm Prediction Center
Chance of a watch: 5%

Counties Andrews County, TX, Borden County, TX, Dawson County, TX, Ector County, TX, Martin County, TX, Ward County, TX

The radar

The Midland/Odessa radar (KMAF), 34 km from the middle of the area, began a volume at 21:49 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Midland Regional, TX (KMAF), launched 12:00Z, 9.8 hours before the alert went out and 34 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1212 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 289 m²/s²
0-3 km storm-relative helicity: 372 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

207 
ACUS11 KWNS 182148
SWOMCD
SPC MCD 182147 
TXZ000-182245-

Mesoscale Discussion 0071
NWS Storm Prediction Center Norman OK
0347 PM CST Sun Feb 18 2018

Areas affected...Parts of west Texas

Concerning...Severe potential...Watch unlikely 

Valid 182147Z - 182245Z

Probability of Watch Issuance...5 percent

SUMMARY...At least isolated strong to severe storm development
appears possible during the 4-6 PM CST time frame, with severe hail
and locally strong wind gusts the primary potential hazards.

DISCUSSION...Weak to moderate destabilization is ongoing near the
dry line across west Texas, with continued boundary layer heating
and mixing.  Latest RAP output suggests CAPE is now on the order of
500-1000 J/kg.  Low-level convergence appears weak, and mid/upper
forcing for ascent unclear, but inhibition appears to be in the
process of becoming increasingly negligible.  At least isolated
thunderstorm development does not appear out of the question within
the next hour or two, probably near or west/southwest of Midland,
based on latest visible imagery.

Given favorable deep layer shear beneath southwesterly mid-level
flow on the order of 40-50 kt, any sustained convection could take
on a supercell structures.  This probably would be accompanied by at
least the risk for severe hail and localized strong surface gusts,
before boundary layer instability wanes after nightfall.

..Kerr/Thompson.. 02/18/2018

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

ATTN...WFO...LUB...MAF...

LAT...LON   31250339 32360272 33110158 33120058 32100184 31550236
            30670330 30880347 31250339

Nearby

Mesoscale Discussions in Texas, 2018 Every mesoscale discussion in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.