Alert archive / Georgia / Mesoscale Discussions in 2018

Mesoscale Discussion 1613

November 1, 20185 counties in Alabama; 14 counties in Florida; 20 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Nov 1, 2018, 8:43 AM CDT for 5 counties in Alabama; 14 counties in Florida; 20 counties in Georgia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Nov 1, 2018, 8:43 AM CDT (13:43 UTC)
Expired
Nov 1, 2018, 10:45 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
60%
All 39 counties

Coffee County, AL, Dale County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Madison County, FL, Wakulla County, FL, Walton County, FL, Washington County, FL, Baker County, GA, Brooks County, GA, Calhoun County, GA, Clay County, GA, Colquitt County, GA, Cook County, GA, Decatur County, GA, Dougherty County, GA, Early County, GA, Grady County, GA, Lee County, GA, Miller County, GA, Mitchell County, GA, Quitman County, GA, Randolph County, GA, Seminole County, GA, Terrell County, GA, Thomas County, GA, Tift County, GA, Worth County, GA

The radar

The Tallahassee radar (KTLH), 73 km from the middle of the area, began a volume at 13:48 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, 1.7 hours before the alert went out and 75 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, Tallahassee Rgnl, FL at 12:00Z on 2018-11-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 21 joules per kilogram.LCLLFCEL10008507005003002001001 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, Tallahassee Rgnl, FL at 12:00Z on 2018-11-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 241 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
21 J/kg
Mixed-layer CIN
-16 J/kg
Mixed-layer LCL
739 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
241 m²/s²
0-3 km storm-relative helicity
221 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

346 
ACUS11 KWNS 011343
SWOMCD
SPC MCD 011343 
GAZ000-FLZ000-ALZ000-011545-

Mesoscale Discussion 1613
NWS Storm Prediction Center Norman OK
0843 AM CDT Thu Nov 01 2018

Areas affected...the Florida Panhandle into southwest Georgia and
southeast Alabama

Concerning...Severe potential...Watch possible 

Valid 011343Z - 011545Z

Probability of Watch Issuance...60 percent

SUMMARY...A line of thunderstorms will progress eastward across the
Florida Panhandle, southeast Alabama and southern Georgia today,
with the main severe risk being damaging wind gusts.

DISCUSSION...A line of storms currently extends along the length of
central AL into the western FL Panhandle. The air mass ahead of this
line becomes much drier with eastward extent due to a surface ridge.
The 12Z TLH sounding showed almost no MUCAPE, with poor lapse rates
aloft. 

Southerly surface winds will persist throughout the day, although
there will be some veering as the main surface low continues to move
northward away from the region. This will allow marginal
destabilization across mainly the FL Panhandle, where a return to
68-70 F dewpoints will allow for a few hundred J/kg MUCAPE to
develop. Modest flow in the boundary layer along with heating/mixing
may aid wind gust potential with a primarily linear storm mode.
Additional activity ahead of the line is not expected due to the
weak instability and presence of an inversion below 700 mb.

..Jewell/Grams.. 11/01/2018

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FFC...TAE...BMX...MOB...

LAT...LON   30348662 30828637 31538624 31948505 31898413 31588354
            30988326 30318347 29928379 30038411 29758452 29528513
            29718542 29938561 30198597 30288633 30348662

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Nov 1, 4:30 AM CDTMesoscale DiscussionSPCAutauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 23 more2 hr
Nov 1, 5:27 AM CDTTornado WatchSPCAutauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 32 more7 hr
Nov 1, 7:50 AM CDTMesoscale DiscussionSPCAutauga, Baldwin, Bibb, Butler, Chilton, Clarke and 22 more115 min
Nov 1, 9:40 AM CDTSevere Thunderstorm WatchSPCBarbour, Bullock, Coffee, Dale, Geneva, Henry and 3 more4 hr
Nov 1, 12:03 PM CDTMesoscale DiscussionSPCChambers, Cherokee, Cleburne, DeKalb, Henry, Houston and 3 more117 min

Nearby

Mesoscale Discussions in Georgia, 2018Mesoscale Discussions in Florida, 2018Mesoscale Discussions in Alabama, 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.