Alert archive / Oklahoma / Mesoscale Discussions in 2017
Mesoscale Discussion 765
The Storm Prediction Center issued this mesoscale discussion at May 18, 2017, 5:15 PM CDT for Harper County, Sumner County, Kansas; 7 counties in Oklahoma. It was in force for 60 min.
The area
The outline as issued.
The facts
- Issued
- May 18, 2017, 5:15 PM CDT (22:15 UTC)
- Expired
- May 18, 2017, 6:15 PM CDT
- In force
- 60 min
- Issued by
- the Storm Prediction Center
Counties Harper County, KS, Sumner County, KS, Alfalfa County, OK, Blaine County, OK, Garfield County, OK, Grant County, OK, Kingfisher County, OK, Major County, OK, Woods County, OK
The radar
The Vance AFB radar (KVNX), 35 km from the middle of the area, began a volume at 22:16 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Norman, OK (KOUN), launched 12:00Z, 10.3 hours before the alert went out and 161 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
- 1272 J/kg
- Mixed-layer CIN
- -210 J/kg
- Mixed-layer LCL
- 1122 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 231 m²/s²
- 0-3 km storm-relative helicity
- 250 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.9
The text
As transmitted.
792
ACUS11 KWNS 182216
SWOMCD
SPC MCD 182215
OKZ000-KSZ000-182315-
Mesoscale Discussion 0765
NWS Storm Prediction Center Norman OK
0515 PM CDT Thu May 18 2017
Areas affected...central and north-central OK into far southern KS
Concerning...Tornado Watch 235...239...
Valid 182215Z - 182315Z
The severe weather threat for Tornado Watch 235, 239 continues.
SUMMARY...A heightened tornado risk may evolve northwest of the OKC
metro---dependent on slightly less supportive storm-scale
interactions resolving in the near term.
DISCUSSION...Radar mosaic shows as cluster of tornadic supercells
over northwest OK and supercells with a history of tornadoes over
central OK near the I-40 corridor in west-central OK. The
near-storm environment is forecast to become more favorable for
strong tornadoes over the next 2 hours as backed east-southeasterly
low level flow strengthens in the inflow regions of the established
supercells. Forecast soundings show 0-1 km SRH over central and
north-central OK in the 50-75 m2/s2 range (NAM/RAP). This is in
contrast to observed KTLX VAD data showing around 150 m2/s2 0-1 km
SRH with weaker SRH near KVNX. The short-term models indicate SRH
will increase and the expectation is for 0-1 km SRH to increase into
the 150-300 m2/s2 range. This will likely prove favorable for
intensifying low-level mesocyclones/increased tornado potential. As
storms move farther east, a reservoir of richer low-level moisture
is located over north-central OK (likely a partial function of
evapotranspiration due to excessive rains earlier this month). As
storms encounter the slightly higher moisture (into the upper 60s
degrees F) and strengthening low-level shear, an intense longer
track tornado may develop over central/north-central OK this
evening.
..Smith.. 05/18/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ICT...OUN...DDC...
LAT...LON 35839885 36359891 36929885 37409849 37389769 37089723
35939744 35479850 35839885SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 18, 2:00 PM CDT | Mesoscale Discussion | SPC | Barber, Barton, Butler, Chase, Chautauqua, Clark and 20 more | 90 min |
| May 18, 2:16 PM CDT | Mesoscale Discussion | SPC | Anderson, Chase, Coffey, Douglas, Franklin, Johnson and 7 more | 119 min |
| May 18, 3:00 PM CDT | Tornado Watch | SPC | Anderson, Atchison, Brown, Clay, Cloud, Coffey and 24 more | 7 hr |
| May 18, 3:21 PM CDT | Tornado Watch | SPC | Barber, Barton, Butler, Chase, Chautauqua, Clark and 31 more | 7 hr |
| May 18, 3:42 PM CDT | Mesoscale Discussion | SPC | Gove, Grant, Greeley, Hamilton, Kearny, Logan and 8 more | 93 min |
| May 18, 12:59 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Beckham, Blaine, Caddo, Comanche, Cotton and 14 more | 2 hr |
| May 18, 1:18 PM CDT | Tornado Watch | SPC | Alfalfa, Beckham, Blaine, Caddo, Canadian, Carter and 31 more | 7 hr |
| May 18, 3:02 PM CDT | Mesoscale Discussion | SPC | Beckham, Caddo, Comanche, Cotton, Grady, Greer and 6 more | 88 min |
| May 18, 5:47 PM CDT | Mesoscale Discussion | SPC | Craig, Creek, Hughes, Lincoln, Mayes, Nowata and 10 more | 28 min |
| May 18, 6:02 PM CDT | Tornado Watch | SPC | Adair, Cherokee, Coal, Craig, Creek, Delaware and 26 more | 7 hr |
Nearby
Mesoscale Discussions in Oklahoma, 2017Mesoscale Discussions in Kansas, 2017Every mesoscale discussion in 2017
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.