Alert archive / Alabama / Mesoscale Discussions in 2016

Mesoscale Discussion 658

May 20, 201610 counties in Alabama; 5 counties in Florida; Wayne County, Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 20, 2016, 1:26 AM CDT for 10 counties in Alabama; 5 counties in Florida; Wayne County, Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 20, 2016, 1:26 AM CDT (06:26 UTC)
Expired: May 20, 2016, 3:30 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Baldwin County, AL, Butler County, AL, Clarke County, AL, Conecuh County, AL, Covington County, AL, Escambia County, AL, Geneva County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Escambia County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Wayne County, MS

The radar

The Mobile radar (KMOB), 71 km from the middle of the area, began a volume at 06:30 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.

Severe Thunderstorm Watch 185May 20, 3:05 AM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 6.4 hours before the alert went out and 219 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 2145 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: -6 m²/s²
0-3 km storm-relative helicity: 48 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

549 
ACUS11 KWNS 200627
SWOMCD
SPC MCD 200626 
FLZ000-ALZ000-MSZ000-200830-

MESOSCALE DISCUSSION 0658
NWS STORM PREDICTION CENTER NORMAN OK
0126 AM CDT FRI MAY 20 2016

AREAS AFFECTED...SE MS...SRN AL AND WRN FL PANHANDLE

CONCERNING...SEVERE THUNDERSTORM WATCH 183...184...

VALID 200626Z - 200830Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
183...184...CONTINUES.

SUMMARY...A THREAT FOR WIND DAMAGE AND HAIL WILL CONTINUE FOR
SEVERAL MORE HOURS AS A LINE OF STORMS MOVES EWD ACROSS SRN AL AND
INTO THE WRN FL PANHANDLE. NEW WW ISSUANCE MAY NEED TO BE CONSIDERED
TO THE EAST OF WW 184 AS THE LINE APPROACHES THE ERN EDGE OF THE
WATCH EARLY THIS MORNING.

DISCUSSION...THE LATEST RADAR DATA FROM MOBILE SHOWS A WELL
ORGANIZED BOWING LINE SEGMENT WITH A MESOVORTEX IN ITS WAKE. THIS
QLCS IS LOCATED ALONG THE NRN EDGE OF MODERATE INSTABILITY WHERE THE
RAP IS ESTIMATING MLCAPE IN THE 1500 TO 2000 J/KG RANGE. IN ADDITION
TO THE MOIST AND UNSTABLE AIRMASS...STRONG ASCENT ASSOCIATED WITH
THE MCV AND A 60 TO 75 KT MID-LEVEL JET ANALYZED JUST BEHIND THE
QLCS...IS PROVIDING SUPPORT FOR THE ORGANIZED BOWING STRUCTURE. THE
QLCS IS MOVING EWD AT ABOUT 45 KT WHICH WILL MAKE WIND DAMAGE LIKELY
ALONG THE LEADING EDGE. THE SEVERE THREAT WILL CONTINUE FOR SEVERAL
MORE HOURS ACROSS SRN AL AND INTO THE WRN FL PANHANDLE BUT MAY START
TO BECOME MORE ISOLATED TOWARD DAYBREAK.

..BROYLES/THOMPSON.. 05/20/2016

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

ATTN...WFO...TAE...BMX...MOB...JAN...LIX...

LAT...LON   31648908 31058845 30218836 29628842 29568761 29858626
            30468583 31148580 31708622 32058753 31648908

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 19, 10:52 PM CDT	Severe Thunderstorm Watch	SPC	Baldwin, Clarke, Conecuh, Covington, Escambia, Mobile and 2 more	6 hr
May 20, 3:10 AM CDT	Severe Thunderstorm Watch	SPC	Coffee, Dale, Geneva, Henry, Houston	5 hr
May 20, 2:33 PM CDT	Mesoscale Discussion	SPC	Blount, Cullman, Fayette, Franklin, Jefferson, Lamar and 10 more	2 hr
May 20, 6:27 AM CDT	Mesoscale Discussion	SPC	Franklin, Gadsden, Jefferson, Leon, Liberty, Madison and 2 more	93 min
May 19, 10:22 PM CDT	Mesoscale Discussion	SPC	George, Hancock, Harrison, Jackson, Pearl River, Stone	83 min

Nearby

Mesoscale Discussions in Alabama, 2016 Mesoscale Discussions in Florida, 2016 Mesoscale Discussions in Mississippi, 2016 Every mesoscale discussion in 2016

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.