Alert archive / Alabama / Tornado Watches in 2017

Tornado Watch 497

October 7, 20177 counties in Alabama; Escambia County, Okaloosa County, Santa Rosa County, Florida; George County, Greene County, Jackson County, Mississippi

The Storm Prediction Center issued this tornado watch at Oct 7, 2017, 7:05 PM CDT for 7 counties in Alabama; Escambia County, Okaloosa County, Santa Rosa County, Florida; George County, Greene County, Jackson County, Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Oct 7, 2017, 7:05 PM CDT (00:05 UTC)
Expired
Oct 8, 2017, 2:00 AM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
0.5 in
Strongest gust expected
60 kt

Counties Baldwin County, AL, Clarke County, AL, Conecuh County, AL, Escambia County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, George County, MS, Greene County, MS, Jackson County, MS

The radar

The Mobile radar (KMOB), 40 km from the middle of the area, began a volume at 00:06 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
40%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
20%
One or more gusts of 65 knots or more
5%
Ten or more severe hail reports
5%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
50%

Warnings issued inside it

13 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Oct 7, 7:28 PM CDTTornado WarningMOBBaldwin, Mobile, Washington47 min
Oct 7, 7:28 PM CDTTornado WarningMOBBaldwin, Mobile32 min
Oct 7, 8:11 PM CDTTornado WarningMOBWashington20 min
Oct 7, 9:13 PM CDTTornado WarningMOBBaldwin32 min
Oct 7, 9:27 PM CDTTornado WarningMOBBaldwin48 min
Oct 7, 9:43 PM CDTTornado WarningMOBBaldwin32 min
Oct 7, 9:52 PM CDTFlash Flood WarningMOBBaldwin6 hr
Oct 7, 9:56 PM CDTFlash Flood WarningMOBGeorge, Greene, Perry, Stone6 hr
Oct 7, 11:01 PM CDTFlash Flood WarningMOBBaldwin, Clarke, Escambia, Mobile, Monroe, Washington6 hr
Oct 7, 11:46 PM CDTFlash Flood WarningMOBBaldwin, Conecuh, Escambia, Monroe6 hr
Oct 8, 12:58 AM CDTTornado WarningMOBOkaloosa32 min
Oct 8, 1:18 AM CDTTornado WarningMOBOkaloosa27 min
Oct 8, 1:31 AM CDTFlash Flood WarningMOBChoctaw, Clarke, Conecuh, Monroe, Washington, Wilcox6 hr

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 0.1 hours before the alert went out and 188 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.

Skew-T log-pSkew-T log-p diagram, Slidell Radar S, LA at 00:00Z on 2017-10-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 00:00Z on 2017-10-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -81 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
601 m above ground
0-6 km bulk shear
12 kt
0-1 km storm-relative helicity
-81 m²/s²
0-3 km storm-relative helicity
-6 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

013 
WWUS20 KWNS 080002
SEL7  
SPC WW 080002
ALZ000-FLZ000-MSZ000-CWZ000-080700-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 497
NWS Storm Prediction Center Norman OK
705 PM CDT Sat Oct 7 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southern Alabama
  Western Florida Panhandle
  Southeast Mississippi
  Coastal Waters

* Effective this Saturday night and Sunday morning from 705 PM
  until 200 AM CDT.

* Primary threats include...
  A couple tornadoes possible
  Isolated damaging wind gusts to 70 mph possible

SUMMARY...As the center of Hurricane Nate moves northward, shear
profiles and the risk of isolated tornadoes will increase across the
watch area.

The tornado watch area is approximately along and 55 statute miles
north and south of a line from 35 miles west of Mobile AL to 10
miles southeast of Crestview FL. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

&&

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 15035.

...Hart

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 8, 1:13 AM CDTMesoscale DiscussionSPCBarbour, Bullock, Butler, Coffee, Conecuh, Covington and 12 more92 min
Oct 8, 1:41 AM CDTTornado WatchSPCAutauga, Barbour, Bullock, Butler, Coffee, Conecuh and 13 more8 hr
Oct 8, 9:04 AM CDTMesoscale DiscussionSPCAutauga, Barbour, Bullock, Butler, Coffee, Conecuh and 13 more86 min

Nearby

Tornado Watches in Alabama, 2017Tornado Watches in Florida, 2017Tornado Watches in Mississippi, 2017Every tornado watch 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.