Alert archive / Alabama / Mesoscale Discussions in 2017
Mesoscale Discussion 147
The Storm Prediction Center issued this mesoscale discussion at Feb 7, 2017, 11:20 AM CST for 12 counties in Alabama; 6 counties in Florida. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Feb 7, 2017, 11:20 AM CST (17:20 UTC)
- Expired
- Feb 7, 2017, 1:15 PM CST
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
Counties Baldwin County, AL, Butler County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Monroe County, AL, Wilcox County, AL, Escambia County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL
The radar
The Eglin Afb radar (KEVX), 103 km from the middle of the area, began a volume at 17:23 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
Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 5.3 hours before the alert went out and 258 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
- 10 J/kg
- Mixed-layer CIN
- -140 J/kg
- Mixed-layer LCL
- 1140 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 84 m²/s²
- 0-3 km storm-relative helicity
- 147 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
669
ACUS11 KWNS 071721
SWOMCD
SPC MCD 071720
FLZ000-ALZ000-071915-
Mesoscale Discussion 0147
NWS Storm Prediction Center Norman OK
1120 AM CST Tue Feb 07 2017
Areas affected...Southern Alabama through the western Florida
panhandle
Concerning...Severe potential...Watch possible
Valid 071720Z - 071915Z
Probability of Watch Issuance...60 percent
SUMMARY...Threat for severe storms including a couple of tornadoes,
damaging wind and hail is expected to increase over the central Gulf
Coast region into the afternoon.
DISCUSSION...Broken band of storms continues from central and
southwest AL into southern LA. Activity is developing along warm
conveyor belt in association with forcing for ascent attending a
progressive shortwave trough. A poorly defined warm front was
located along the gulf coast area, and this boundary may move
further inland as a secondary branch of the southwesterly low-level
jet shifts east through the central Gulf Coast region today. Primary
limiting factor in this region is marginal instability, and diabatic
warming of the boundary layer remains limited by widespread
multi-layer clouds. However, theta-e advection accompanying the
low-level jet will contribute to at least modest destabilization
which (in conjunction with sufficient (40-45 KT) effective bulk
shear) suggests storms may eventually begin to organize with both
supercells and bowing segments possible. While low-level hodographs
are not particularly large, 0-1 km storm relative helicity will be
sufficient for a few low-level mesocyclones and a couple of
tornadoes. Otherwise, damaging wind and some hail may also occur
with the stronger storms.
..Dial/Thompson.. 02/07/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TAE...BMX...MOB...
LAT...LON 30318813 31478820 32058727 31538530 30328547 30438615
30428689 30318813SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 7, 5:59 AM CST | Mesoscale Discussion | SPC | Baldwin, Choctaw, Clarke, Mobile, Washington | 2 hr |
| Feb 7, 11:50 AM CST | Tornado Watch | SPC | Baldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 6 more | 6 hr |
| Feb 7, 2:44 PM CST | Mesoscale Discussion | SPC | Baldwin, Coffee, Conecuh, Covington, Dale, Escambia and 3 more | 91 min |
| Feb 7, 3:27 PM CST | Severe Thunderstorm Watch | SPC | Bay, Calhoun, Gulf, Holmes, Jackson, Walton and 1 more | 3 hr |
| Feb 7, 4:33 PM CST | Severe Thunderstorm Watch | SPC | Dixie, Franklin, Gadsden, Jefferson, Lafayette, Leon and 4 more | 4 hr |
| Feb 7, 5:24 PM CST | Mesoscale Discussion | SPC | Calhoun, Gadsden, Jefferson, Leon, Liberty, Madison and 2 more | 96 min |
| Feb 7, 5:58 PM CST | Mesoscale Discussion | SPC | Alachua, Baker, Bradford, Clay, Columbia, Duval and 5 more | 3 hr |
Nearby
Mesoscale Discussions in Alabama, 2017Mesoscale Discussions in Florida, 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.