Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 70
The Storm Prediction Center issued this mesoscale discussion at Feb 11, 2021, 9:13 AM CST for 19 counties in Texas. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 11, 2021, 9:13 AM CST (15:13 UTC)
- Expired
- Feb 11, 2021, 1:15 PM CST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Winter mixed precipitation
Counties Bell County, TX, Burnet County, TX, Coryell County, TX, Falls County, TX, Gillespie County, TX, Hamilton County, TX, Kimble County, TX, Lampasas County, TX, Limestone County, TX, Llano County, TX, Mason County, TX, McCulloch County, TX, McLennan County, TX, Menard County, TX, Milam County, TX, Mills County, TX, Robertson County, TX, San Saba County, TX, Williamson County, TX
The radar
The Ft Hood radar (KGRK), 126 km from the middle of the area, began a volume at 15:14 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
Fort Worth, TX (KFWD), launched 12:00Z, 3.2 hours before the alert went out and 240 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.
- Mixed-layer CAPE
- 6 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 478 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 157 m²/s²
- 0-3 km storm-relative helicity
- 254 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
171 ACUS11 KWNS 111513 SWOMCD SPC MCD 111513 TXZ000-111915- Mesoscale Discussion 0070 NWS Storm Prediction Center Norman OK 0913 AM CST Thu Feb 11 2021 Areas affected...Central TX Concerning...Winter mixed precipitation Valid 111513Z - 111915Z SUMMARY...Freezing rain rates are expected to increase across central TX during the next several hours. Some sleet is also possible. DISCUSSION...Persistent isentropic ascent will persist ahead of the approaching shortwave trough across the southern Plains for at least the next several hours. Expectation is for the ongoing band of precipitation from the Edwards Plateau into central TX to continue while gradually shifting northeastward. Current surface analysis places the freezing line from about 20-30 miles north of DRT northeastward to just south of AUS and then further northeastward into east TX. This cold air is shallow, with forecast soundings showing sub-freezing temperatures extend to about 2000-2500 ft with temperatures continuing to increase above that level to around 10 deg C by 3500-400 ft (around 850 mb). This warm noise above the shallow cold layer is expected to result in primarily freezing rain, although some sleet could also mix in. Relatively dry mid-levels currently in place are expected to moisten over time, contributing to heavier precipitation rates at the surface. Most sites are not currently reporting precipitation at the surface but that is expected to change soon as the precipitation rates increase. One exception at Llano, TX (AQO) which reported 0.05" of liquid over the past hour. Additionally, Burnett, TX (BMQ) reported 0.02" of ice accretion over the past hour. This trend of measurable precipitation at the surface and ice accretion is expected to continue eastward into more of central TX over the next several hours. ..Mosier.. 02/11/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...HGX...FWD...EWX...SJT... LAT...LON 30710054 31869830 31979618 30919617 29890020 30710054
Nearby
Mesoscale Discussions in Texas, 2021Every 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.