Alert archive / Texas / Mesoscale Discussions in 2018
Mesoscale Discussion 101
The Storm Prediction Center issued this mesoscale discussion at Feb 28, 2018, 11:54 PM CST for 7 counties in Texas. It was in force for 66 min.
The area
The outline as issued.
The facts
- Issued
- Feb 28, 2018, 11:54 PM CST (05:54 UTC)
- Expired
- Mar 1, 2018, 1:00 AM CST
- In force
- 66 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 5%
Counties Bell County, TX, Burnet County, TX, Coryell County, TX, Falls County, TX, Llano County, TX, Milam County, TX, Williamson County, TX
The radar
The Ft Hood radar (KGRK), 47 km from the middle of the area, began a volume at 05:57 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 00:00Z, 5.9 hours before the alert went out and 227 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
- 493 J/kg
- Mixed-layer CIN
- -37 J/kg
- Mixed-layer LCL
- 478 m above ground
- 0-6 km bulk shear
- 84 kt
- 0-1 km storm-relative helicity
- 228 m²/s²
- 0-3 km storm-relative helicity
- 208 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 2.7
The text
As transmitted.
651
ACUS11 KWNS 010555
SWOMCD
SPC MCD 010554
TXZ000-010700-
Mesoscale Discussion 0101
NWS Storm Prediction Center Norman OK
1154 PM CST Wed Feb 28 2018
Areas affected...parts of central TX
Concerning...Severe potential...Watch unlikely
Valid 010554Z - 010700Z
Probability of Watch Issuance...5 percent
SUMMARY...A couple of stronger storms may be capable of a marginally
severe hail threat for the next 1-2 hours. The coverage/duration of
the anticipated threat will preclude a severe thunderstorm watch.
DISCUSSION...Radar imagery shows a couple of weak supercells within
a broken band of convection over central TX from Mason County
northeast into Lampasas County as of 0550Z. Surface observations to
the east of the storms show temperatures around 70 degrees F and
dewpoints around 67. It appears the RAP forecast soundings are
accurately capturing the surface conditions and the sounding profile
exhibits poor 0-3 km lapse rates less than 5 degrees C/km. As a
result, substantial CINH is present and the convection should remain
slightly elevated in character---this notion is also supported by
the storms being located behind the windshift. Given the poor
low-level lapse rates, it seems the wind damage risk will be limited
owing to the lack of overall potential for evaporative
cooling/momentum transport mechanisms for an isolated severe gust.
Therefore, marginally severe hail will likely be the risk with the
stronger updraft pulses during the next 1-2 hours before storms
weaken.
..Smith/Thompson.. 03/01/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...EWX...SJT...
LAT...LON 30429917 31429793 31429682 31159667 30649709 30439814
30429917SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 28, 6:43 PM CST | Mesoscale Discussion | SPC | Bosque, Brown, Coleman, Collin, Comanche, Concho and 25 more | 62 min |
Nearby
Mesoscale Discussions in Texas, 2018Every 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.