Alert archive / Mississippi / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 27, NWS New Orleans, LA

April 12, 2020Saint Tammany Parish, Louisiana; Hancock County, Harrison County, Pearl River County, Mississippi

NWS New Orleans, LA issued this severe thunderstorm warning at Apr 12, 2020, 9:08 PM CDT for Saint Tammany Parish, Louisiana; Hancock County, Harrison County, Pearl River County, Mississippi. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Apr 12, 2020, 9:08 PM CDT (02:08 UTC)
Expired
Apr 12, 2020, 9:39 PM CDT
In force
31 min
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Saint Tammany Parish, LA, Hancock County, MS, Harrison County, MS, Pearl River County, MS

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Apr 12, 1:24 PM CDTTornado WatchSPC9 hr

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 2.1 hours before the alert went out and 32 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 2020-04-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2085 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, Slidell Radar S, LA at 00:00Z on 2020-04-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 201 square meters per square second.1939587897117Sfc1 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
2085 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
659 m above ground
0-6 km bulk shear
83 kt
0-1 km storm-relative helicity
201 m²/s²
0-3 km storm-relative helicity
224 m²/s²
Significant tornado parameter
3.0
Supercell composite
9.5

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS New Orleans, LA wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 12, 4:04 PM CDT, 5 hours 4 minutes earlier.

Area forecast discussion, Apr 12, 4:04 PM CDT, 5 hours 4 minutes before
Area Forecast Discussion
National Weather Service New Orleans LA
404 PM CDT Sun Apr 12 2020

.SYNOPSIS...

Surface low over northwest Arkansas at 3 PM CDT, with a cold front
to near Houston. Upper trough over southern Oklahoma, per water
vapor loops. LIX 18z sounding continued to show a cap at 850 mb,
which is inhibiting storms from moving much further eastward than
a McComb to Baton Rouge line at this time. We will be launching a
special sounding shortly to reassess lower levels of the
atmosphere over the eastern half of the area. Tornado Watch 107
continues until 8 PM for northern half of the CWA.

&&

.SHORT TERM...

Short range models show highest threat of severe weather likely to
be north of our CWA, but still enough potential here to not change
the message at this time. All precipitation should be clear of our
area by 07-08z. Will continue Wind Advisory and Coastal Flood
Advisory as currently configured. Water levels 1 to 1.5 feet above
normal. Once wind direction shifts, water levels should start
diminishing. Dry Monday through Tuesday afternoon. As front
becomes parallel to upper flow, could have a period of showers
and/or storms move over the coastal waters and possibly coastal
areas Tuesday night.

Will go with blended temperatures for the short range as not a
major discrepancy for most of the area.

&&

.LONG TERM...

Timing differences exist for the next system next weekend, will
continue using blended solutions until a preferred solution
becomes apparent.

&&

.AVIATION...

Outside of convection, MVFR to VFR ceilings common. Convection
will lower to IFR conditions. Southerly wind gusts 30+ knots
likely producing significant crosswind issues on E-W runway
configurations. LLWS also likely until cold frontal passage. Should
see improvement to VFR behind front.

&&

.MARINE...

No change to current headlines, Small Craft Advisories verifying
well, with a few of the elevated oil platforms seeing an
occasional gust to gale force. Winds should relax behind frontal
passage as pressure gradient eases and cold advection remains to
the north. Winds will increase to the 15-20 knot range again
around Tuesday night as wave moves along the front over the Gulf
of Mexico with these trends continuing into Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  60  75  52  77 /  30   0   0  10
BTR  58  74  52  78 /  20   0   0  20
ASD  62  81  55  81 /  60   0   0  20
MSY  64  80  61  80 /  50   0   0  20
GPT  65  81  57  78 /  50   0   0  20
PQL  63  84  55  82 /  70   0   0  30

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Wind Advisory until 10 PM CDT this evening for LAZ034>037-039-
     040-046>050-056>072.

     Coastal Flood Advisory until 7 PM CDT this evening for LAZ040-
     050-058-060>062-064-066>070-072.

GM...Small Craft Advisory until 10 PM CDT this evening for GMZ530-534-
     550-552-570-572.

     Small Craft Advisory until 4 AM CDT Monday for GMZ532-536-538-
     555-557-575-577.

MS...Wind Advisory until 10 PM CDT this evening for MSZ068>071-077-
     080>082.

     Coastal Flood Advisory until 7 PM CDT this evening for
     MSZ080>082.

GM...Small Craft Advisory until 10 PM CDT this evening for GMZ534-550-
     552-570-572.

     Small Craft Advisory until 4 AM CDT Monday for GMZ536-538-555-
     557-575-577.

&&

In the hours before

Local storm report, Apr 12, 5:17 PM CDT, 3 hours 51 minutes before
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Local storm report, Apr 12, 6:05 PM CDT, 3 hours 3 minutes before
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Special weather statement, Apr 12, 6:07 PM CDT, 3 hours 1 minute before
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Special weather statement, Apr 12, 6:35 PM CDT, 2 hours 33 minutes before
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Special weather statement, Apr 12, 6:39 PM CDT, 2 hours 29 minutes before
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Special weather statement, Apr 12, 6:46 PM CDT, 2 hours 22 minutes before
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The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 12, 7:02 PM CDTSevere Thunderstorm WarningLIXLivingston, Tangipahoa43 min
Apr 12, 8:29 PM CDTSpecial Weather StatementLIXSaint Tammany31 min
Apr 12, 9:54 PM CDTSmall Craft AdvisoryLIX18 hr
Apr 13, 5:46 AM CDTDense Fog AdvisoryLIXAssumption, Saint James3 hr
Apr 12, 8:40 PM CDTSevere Thunderstorm WarningLIXAmite, Wilkinson33 min
Apr 12, 8:56 PM CDTSpecial Weather StatementLIXHancock, Pearl River64 min
Apr 12, 9:56 PM CDTSpecial Weather StatementLIXPike, Walthall49 min

Nearby

Severe Thunderstorm Warnings in Mississippi, 2020Severe Thunderstorm Warnings in Louisiana, 2020Every severe thunderstorm warning in 2020

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.