Mesoscale Discussion 921

Issued

May 26, 2022, 5:04 AM CDT (10:04 UTC)

Expired

May 26, 2022, 7:30 AM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

Counties Baldwin County, AL, Covington County, AL, Escambia County, AL, Geneva County, AL, Mobile County, AL, Bay County, FL, Escambia County, FL, Gulf County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Jefferson Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, George County, MS, Harrison County, MS, Jackson County, MS

The Mobile radar (KMOB), 89 km from the middle of the area, began a volume at 10:04 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.

• Tornado Watch 274May 26, 7:45 AM CDT

102 
ACUS11 KWNS 261004
SWOMCD
SPC MCD 261004 
FLZ000-ALZ000-MSZ000-LAZ000-261230-

Mesoscale Discussion 0921
NWS Storm Prediction Center Norman OK
0504 AM CDT Thu May 26 2022

Areas affected...Parts of southeastern Louisiana and
Mississippi...southern Alabama and the western Florida Panhandle

Concerning...Severe potential...Watch possible 

Valid 261004Z - 261230Z

Probability of Watch Issuance...40 percent

SUMMARY...The risk for severe weather appears generally low in the
near term, but increasing thunderstorm activity may gradually
consolidate and organize near, if not along or inland of, coastal
areas through 9-10 AM CDT.  Eventually this may be accompanied by a
more widespread risk for potentially damaging wind gusts and a
couple of tornadoes, which could require a severe weather watch
issuance.

DISCUSSION...Although a gradual mid-level cooling is underway
associated with the slow eastward progression of a seasonably deep
large-scale mid-level trough into the lower/middle Mississippi
Valley, the pre-cold frontal boundary layer inland of northern Gulf
coastal areas has been impacted considerably by prior convection. 
It remains potentially cool and stable over a fairly broad area
centered over southern Alabama, and unlikely to modify substantially
through at least mid morning.

Thunderstorm activity has been increasing during the past few hours
south-southwest of the southeastern Louisiana coast.  This appears
to be occurring within a broad pre-frontal low-level confluence
zone, along which a seasonably moist boundary-layer appears to be
contributing to CAPE in excess of 2000 J/kg.  Within weak surface
troughing, a surface low may be forming across southeastern
Louisiana, along a weak convectively reinforced baroclinic zone
extending near coastal areas into the Florida Panhandle vicinity.

Through 14-15Z, it appears that this baroclinic zone will become a
focus for a further increase in thunderstorm activity.  Persistent
convective development is already ongoing downstream, offshore of
coastal areas to the south of Panama City.  And a gradual upscale
growth and consolidation of convection is possible.  Southerly
low-level wind fields are generally a relatively modest 20-30 kt
around 850 mb, but deep-layer shear may be sufficient to eventually
contribute to an increasingly organized cluster capable of producing
potentially damaging wind gusts and perhaps a couple of brief
tornadoes.

..Kerr/Edwards.. 05/26/2022

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

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

LAT...LON   30038974 30658912 31028845 31408704 31288566 29448490
            29318655 28518812 28328905 28769079 30038974

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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.