Alert archive / Louisiana / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 98, NWS New Orleans, LA

August 14, 2020Saint Tammany Parish, Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Aug 14, 2020, 5:43 AM CDT for Saint Tammany Parish, Louisiana. It was in force for 21 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
Aug 14, 2020, 5:43 AM CDT (10:43 UTC)
Expired
Aug 14, 2020, 6:04 AM CDT
In force
21 min
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Saint Tammany Parish, LA

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 Aug 14, 4:02 AM CDT, 1 hour 41 minutes earlier.

Area forecast discussion, Aug 14, 4:02 AM CDT, 1 hour 41 minutes before
Area Forecast Discussion
National Weather Service New Orleans LA
402 AM CDT Fri Aug 14 2020

.SYNOPSIS...
Upper ridging centered over New Mexico to the west, with the
Bermuda high to the east. Weak troughing over the Mississippi
River Valley, with a shortwave dropping across Missouri and
Kansas. At the surface, a very weak pressure gradient across the
area. Usual nocturnal convection offshore got an early start this
morning, about 3 hours earlier than usual. Also have some
scattered showers/storms dropping southward across northeast
portions of the area. Temperatures at 3 am CDT generally in the
mid 70s with dew points a couple degrees below the temperature.

&&

.SHORT TERM...

Convection allowing models currently not handling ongoing
convection. This would argue for somewhat more instability
available than models suggest. Will carry a bit higher PoPs today,
with categorical values for much of the northeast half of the
area. This should also hold temperatures down a bit compared to
the last couple of days.

Tomorrow should be a bit of a transition day as drier air works
into the area from the north behind the shortwave moving through
the Missouri River Valley. PoPs should be a bit lower than today,
with temperatures a bit warmer.

On Sunday, diverged from the national blends as both GFS and ECMWF
show quite a bit of drying in the column in northwest flow.
Forecast soundings show precipitable water values down to 1.5
inches on the ECMWF at New Orleans at 18z Sunday, with GFS closer
to 1.3 inches. This won't support much, if any, convection over
land on Sunday. MOS PoP guidance from the GFS and ECMWF support
this with numbers less than 15 percent. Have trimmed our numbers
to 20-25%, and would expect that if forecast trends continue, we
might be looking at a completely dry forecast for Sunday. Of
course, this would have an effect on high temperatures, and
accordingly, the MOS numbers produce highs in the mid 90s. If
north winds are strong enough to overcome a potential sea breeze
(roughly 8-10 mph), can't rule out hotter values at Slidell and
on the Mississippi coast.

&&

.LONG TERM...

Monday's forecast scenario is similar to Sunday, and again have
undercut NBM PoP forecast, trending toward GFS/ECMWF operational
solutions. Again will trend toward the upper end of temperature
guidance.

Moisture levels begin a recovery on Tuesday as a very weak upper
low tries to develop at the base of the trough over the area. This
should produce a bit more instability, with diurnally favored
convection for the midweek period.

&&

.AVIATION...

Primary threat of convection will be between 18z and 00z today,
with VCTS currently mentioned at all terminals. Handling short
term convection with amendments, likely to impact KHDC and
possibly KASD prior to 12z package issuance, with brief IFR or
lower visibilities.

&&

.MARINE...

Outside of threats of thunderstorms, overall marine forecast is
fairly quiet. Could be a brief need for Exercise Caution headlines
over some of the eastern waters late tonight into Saturday as an
upper impulse moves through.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  89  74  91  75 /  70  10  50  10
BTR  93  76  94  76 /  70  20  40  10
ASD  91  74  92  75 /  70  20  50  20
MSY  91  78  92  79 /  70  20  30  20
GPT  88  76  90  77 /  70  20  50  20
PQL  90  74  92  74 /  80  40  50  20

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

In the hours before

Special weather statement, Aug 14, 3:57 AM CDT, 1 hour 46 minutes before
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Special weather statement, Aug 14, 4:45 AM CDT, 58 minutes before
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Special weather statement, Aug 14, 5:28 AM CDT, 15 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 14, 3:57 AM CDTSpecial Weather StatementLIXSaint Tammany48 min
Aug 14, 4:45 AM CDTSpecial Weather StatementLIXWashington45 min
Aug 14, 5:28 AM CDTSpecial Weather StatementLIXSaint Tammany47 min
Aug 14, 2:25 PM CDTSpecial Weather StatementLIXWashington50 min
Aug 14, 3:19 PM CDTSpecial Weather StatementLIXSaint Tammany, Tangipahoa41 min
Aug 14, 3:52 PM CDTSpecial Weather StatementLIXSaint Tammany38 min
Aug 14, 3:54 PM CDTSpecial Marine WarningLIX66 min
Aug 14, 4:03 PM CDTSpecial Marine WarningLIX57 min
Aug 14, 4:20 PM CDTSpecial Weather StatementLIXOrleans25 min
Aug 14, 5:04 PM CDTSpecial Weather StatementLIXJefferson26 min
Aug 14, 5:08 PM CDTSpecial Weather StatementLIXOrleans22 min
Aug 14, 5:48 PM CDTSpecial Marine WarningLIX57 min
Aug 14, 6:12 PM CDTSpecial Marine WarningLIX33 min
Aug 14, 6:17 PM CDTSpecial Weather StatementLIXPlaquemines58 min
Aug 14, 2:00 PM CDTSpecial Weather StatementLIXPike, Walthall45 min
Aug 14, 3:01 PM CDTSevere Thunderstorm WarningLIXPearl River29 min
Aug 14, 3:31 PM CDTSpecial Weather StatementLIXStone29 min
Aug 14, 3:35 PM CDTSpecial Weather StatementLIXJackson40 min
Aug 14, 3:59 PM CDTSpecial Weather StatementLIXHarrison, Jackson46 min

Nearby

Severe 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.