Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 147

March 5, 20214 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Mar 5, 2021, 3:53 PM CST for 4 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Mar 5, 2021, 3:53 PM CST (21:53 UTC)
Expired: Mar 5, 2021, 6:00 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

Counties Hardin County, TX, Liberty County, TX, Polk County, TX, San Jacinto County, TX

The radar

The Houston radar (KHGX), 109 km from the middle of the area, began a volume at 21:55 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

Lake Charles Mun, LA (KLCH), launched 12:00Z, 9.9 hours before the alert went out and 159 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: 931 m above ground
0-6 km bulk shear: 0 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 0 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

918 
ACUS11 KWNS 052153
SWOMCD
SPC MCD 052153 
TXZ000-060000-

Mesoscale Discussion 0147
NWS Storm Prediction Center Norman OK
0353 PM CST Fri Mar 05 2021

Areas affected...Parts of southeast Texas

Concerning...Severe potential...Watch unlikely 

Valid 052153Z - 060000Z

Probability of Watch Issuance...5 percent

SUMMARY...An isolated strong thunderstorm or two is possible near
and north through east of the Greater Houston Metropolitan area
through about 4-6 PM.  This may be accompanied by small to, perhaps,
marginally severe hail and a few strong wind gusts.

DISCUSSION...Attempts at deep convective development appear underway
east through south of Huntsville, where insolation has contributed
to a local maximum in boundary-layer destabilization (mixed-layer
CAPE up to around 500 J/kg) during the past few hours.  This
probably is being supported by weak convergence and low-level warm
advection, near an area of low pressure within weak surface
troughing.  Mid/upper forcing for ascent does not appear
particularly strong, but, based on latest Rapid Refresh forecast
soundings, ongoing convection might be able to intensify into one or
two thunderstorms near and north through east of the Greater Houston
Metropolitan area through 22-00Z.

If this occurs, shear within the cloud-bearing layer is strong and
low-level lapse rates are becoming fairly steep.  Aided by
relatively cool thermodynamic profiles, small to, perhaps,
marginally severe hail will be possible.  Melting hail and
evaporative cooling in the sub-cloud layer could also contribute to
locally strong strong surface gusts, before convection weakens with
the loss of daytime heating.

..Kerr/Dial.. 03/05/2021

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

ATTN...WFO...LCH...HGX...

LAT...LON   30969474 30809448 30309419 29849438 29709474 29769513
            30239542 30749527 30979508 30969474

Nearby

Mesoscale Discussions in Texas, 2021 Every mesoscale discussion in 2021

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.