Alert archive / Alabama / Mesoscale Discussions in 2013

Mesoscale Discussion 1913

September 24, 20137 counties in Alabama; 6 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Sep 24, 2013, 6:33 PM CDT for 7 counties in Alabama; 6 counties in Florida. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued
Sep 24, 2013, 6:33 PM CDT (23:33 UTC)
Expired
Sep 24, 2013, 8:30 PM CDT
In force
117 min
Issued by
the Storm Prediction Center

Counties Baldwin County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Dale County, AL, Escambia County, AL, Geneva 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), 77 km from the middle of the area, began a volume at 23:36 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 nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 11.6 hours before the alert went out and 232 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 2013-09-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 466 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 2013-09-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 45 square meters per square second.1939Sfc1 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
466 J/kg
Mixed-layer CIN
-38 J/kg
Mixed-layer LCL
514 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
45 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

583 
ACUS11 KWNS 242333
SWOMCD
SPC MCD 242333 
FLZ000-ALZ000-250130-

MESOSCALE DISCUSSION 1913
NWS STORM PREDICTION CENTER NORMAN OK
0633 PM CDT TUE SEP 24 2013

AREAS AFFECTED...FAR SRN AL...WRN FL PANHANDLE

CONCERNING...SEVERE THUNDERSTORM WATCH 535...

VALID 242333Z - 250130Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 535
CONTINUES.

SUMMARY...AN ISOLATED DAMAGING WIND THREAT CONTINUES ACROSS THE
REMAINDER OF WW 535. WHILE SOME THREAT WILL LIKELY EXTEND E OF THE
WATCH...OVERALL SVR COVERAGE IS EXPECTED TO BE LOW AND A NEW WW IS
NOT PLANNED.

DISCUSSION...REGIONAL RADAR IMAGERY HAS SHOWN A CONTINUED
FORWARD-PROPAGATING TREND WITH THE LINE OF STORMS MOVING ACROSS SRN
AL AND THE WRN FL PANHANDLE. SOME WIND DAMAGE WAS REPORTED WITH THIS
LINE IN SWRN AL. 

ALTHOUGH THE LINE IS EXPECTED TO CONTINUE EWD INTO SERN AL AND
W-CNTRL FL PANHANDLE...THE LOSS OF DAYTIME HEATING WILL
SIGNIFICANTLY REDUCE INSTABILITY...WITH A RESULTANT DECREASE IN THE
PROBABILITY OF ANY DAMAGING WINDS. HOWEVER...SOME ISOLATED DAMAGING
WINDS WILL REMAIN POSSIBLE AS BOTH BULK SHEAR AND LOW-LEVEL MOISTURE
REMAIN HIGH. ANTICIPATED LOW SVR COVERAGE CURRENTLY PRECLUDES THE
NEED FOR A WW AND A DOWNSTREAM WW IS NOT PLANNED AT THIS TIME.

..MOSIER/MEAD.. 09/24/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...TAE...MOB...

LAT...LON   30428789 31408751 31528662 31478560 30948541 30148589
            30368654 30428789

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 24, 1:33 PM CDTMesoscale DiscussionSPCBaldwin, Choctaw, Clarke, Mobile, Washington87 min
Sep 24, 2:03 PM CDTSevere Thunderstorm WatchSPCBaldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 8 more6 hr
Sep 24, 3:51 PM CDTMesoscale DiscussionSPCBaldwin, Choctaw, Clarke, Mobile, Monroe, Washington84 min
Sep 24, 12:15 PM CDTMesoscale DiscussionSPCBrevard, Broward, Charlotte, Collier, Glades, Hendry and 5 more3 hr

Nearby

Mesoscale Discussions in Alabama, 2013Mesoscale Discussions in Florida, 2013Every mesoscale discussion in 2013

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.