Alert archive / Alabama / Mesoscale Discussions in 2017
Mesoscale Discussion 86
The Storm Prediction Center issued this mesoscale discussion at Jan 21, 2017, 3:00 AM CST for 42 counties in Alabama; 4 counties in Florida. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Jan 21, 2017, 3:00 AM CST (09:00 UTC)
- Expired
- Jan 21, 2017, 4:30 AM CST
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 46 counties
Autauga County, AL, Baldwin County, AL, Barbour County, AL, Bibb County, AL, Bullock County, AL, Butler County, AL, Chambers County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Coffee County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Geneva County, AL, Greene County, AL, Hale County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pike County, AL, Randolph County, AL, Russell County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL
The radar
The Maxwell AFB radar (KMXX), 91 km from the middle of the area, began a volume at 09:01 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
Birmingham, AL (KBMX), launched 00:00Z, 9.0 hours before the alert went out and 127 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
- 1 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1088 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 115 m²/s²
- 0-3 km storm-relative helicity
- 103 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
583
ACUS11 KWNS 210900
SWOMCD
SPC MCD 210900
ALZ000-FLZ000-211030-
Mesoscale Discussion 0086
NWS Storm Prediction Center Norman OK
0300 AM CST Sat Jan 21 2017
Areas affected...Central/southern Alabama and the western Florida
Panhandle
Concerning...Severe potential...Tornado Watch likely
Valid 210900Z - 211030Z
Probability of Watch Issuance...80 percent
SUMMARY...The risk for a few tornadoes, damaging winds, and large
hail will spread east-northeastward into Alabama and the western
Florida Panhandle through sunrise. A tornado watch will likely be
needed by 10z.
DISCUSSION...The ongoing convective cluster and an associated
mesolow in southeast LA/southwest MS will continue to develop/move
northeastward toward AL, in association with an ejecting midlevel
trough (see MCD 0085 for additional information in MS/LA for tornado
watch 10). A strengthening southerly low-level jet will likewise
develop toward AL and enhance the northward transport of low-level
moisture. With at least weak buoyancy rooted at or very near the
surface, increasing low-level shear with the approach of the mesolow
will support an expansion of the tornado risk from MS into AL
through the morning. Thus, a tornado watch will likely be needed by
10z as the initial warm advection storms slowly increase over
southwest AL, and the mesolow approaches the MS/AL state line by
12z.
..Thompson.. 01/21/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TAE...BMX...MOB...
LAT...LON 31618535 30928590 30538617 30418789 30618828 31738836
32788831 33308761 33788621 33738557 33308532 32338511
31618535SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 21, 3:56 AM CST | Tornado Watch | SPC | Autauga, Baldwin, Barbour, Bibb, Bullock, Butler and 36 more | 8 hr |
| Jan 21, 7:41 AM CST | Mesoscale Discussion | SPC | Autauga, Baldwin, Barbour, Bullock, Butler, Chambers and 24 more | 94 min |
| Jan 21, 9:19 AM CST | Mesoscale Discussion | SPC | Barbour, Coffee, Dale, Geneva, Henry, Houston and 1 more | 86 min |
| Jan 21, 8:04 AM CST | Tornado Watch | SPC | Bay, Calhoun, Gadsden, Gulf, Jackson, Liberty and 1 more | 6 hr |
| Jan 21, 12:06 PM CST | Mesoscale Discussion | SPC | Bay, Calhoun, Gadsden, Gulf, Hamilton, Jackson and 6 more | 114 min |
| Jan 21, 1:12 PM CST | Tornado Watch | SPC | Bay, Calhoun, Franklin, Gadsden, Gulf, Jefferson and 3 more | 5 hr |
| Jan 21, 3:03 PM CST | Mesoscale Discussion | SPC | Baker, Columbia, Franklin, Gilchrist, Gulf, Hamilton and 9 more | 57 min |
| Jan 21, 5:05 PM CST | Mesoscale Discussion | SPC | Bay, Calhoun, Franklin, Gulf, Jefferson, Leon and 4 more | 55 min |
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.