Flash Flood Warning 75, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
400 AM CDT Thu Jun 18 2026

...New UPDATE, KEY MESSAGES...

.KEY MESSAGES...
Updated at 354 AM CDT Thu Jun 18 2026

- Potential for Life Threatening Flash Flooding. A Particularly
  Dangerous and Life Threatening Flash Flood Situation exists with
  a High Risk of Flooding across portions of south Mississippi and
  southeast Louisiana, especially east of Interstate 55.
  Considerable Flash Flooding is likely and Catastrophic Flash
  Flooding is possible today.

- A Flood Watch is in effect through Friday morning for most of
  southeast Louisiana as well as all of southwest and coastal
  Mississippi.

- Tornado Watch 348 in effect until 6 AM CDT for most of the area.

- Dangerous conditions for mariners of small craft and minor
  coastal flooding on south facing shores west of the Mississippi
  River will persist through tonight as Post Tropical Cyclone
  Arthur moves into southwest Louisiana.

- Extreme heat is expected this weekend. Heat advisories will
  likely be issued for heat index values of around 110 degrees.

&&

.UPDATE...
Issued at 354 AM CDT Thu Jun 18 2026

Updated Key Messages for WPC's High Risk of Excessive Rainfall
today for portions of the area. Likely to have a fairly large
stripe of 6 to 10 inch rainfall with isolated totals significantly
higher from Houma and Thibodaux northeastward.

&&

.SHORT TERM...
(Now through Sunday)
Issued at 1220 AM CDT Thu Jun 18 2026

Post Tropical Cyclone Arthur has degenerated to a low pressure
area along the Upper Texas Coast. The remnants will continue to
track across western Louisiana overnight and will reach the
Carolinas coastlines by Friday morning. We've already seen some
rotation in radar data, and expect we'll have short-lived spinups
overnight. Additionally, we remain highly concerned about extreme
rainfall amounts overnight. We already had 2.3 inch precipitable
water values at 00z, with guidance indicating that values near 2.6
inches are possible/likely overnight as a 35-40 knot low level jet
plugs in. The 02Z HRRR, for instance, has a large area of rainfall
totals in excess of 6 inches across the area by mid-afternoon
Thursday with spot totals approaching or exceeding 10 inches. If
these totals, or anything close are realized, we're probably
looking at major flooding in those areas. No changes to Flood
Watch anticipated. Could still be scattered precipitation into
Thursday evening associated with this system before we start
seeing some slight drying.

With precipitable water values remaining near 2 inches through
Sunday, still plenty of moisture available for scattered
convection, even without large scale forcing to aid in producing
lift. The large scale heavy rainfall threat will diminish beyond
Thursday evening, but localized heavy rain still possible. Could
also see a few microbursts on Friday.

A second issue over the weekend will be heat stress. We'll likely
see at least some sunshine at times Friday through the weekend
that will allow temperatures to get into the lower, or possibly
middle 90s in many areas. With dew points likely in the upper 70s
to near 80, and lots of residual moisture on the ground, it's
going to be steamy. Likely to have heat index values near our 108
degree criteria for Heat Advisories in many areas on Friday and
possibly again on Sunday. This will be addressed once we get past
the rainfall and tornado issues this morning. Overnight lows may
have trouble getting below 80 degrees for several nights.

&&

.LONG TERM...
(Sunday night through Wednesday)
Issued at 1220 AM CDT Thu Jun 18 2026

Ridging sets up over the northern Gulf for the first half of next
week. However, shortwaves will be tracking west to east just north
of the local area. If we are going to have a day that is
completely dry, it'll probably be Monday. Similar to the weekend,
we'll have to monitor for potential Heat Advisories, especially
Monday. For Tuesday and Wednesday, the question will be exactly
when storms develop. If they develop early enough in the day, that
would blunt the heat somewhat. For now, will stick with the NBM
forecast temperatures with several days seeing highs in the lower
and middle 90s.

&&

.AVIATION...
(06Z TAFS)
Issued at 1220 AM CDT Thu Jun 18 2026

Conditions currently at VFR to MVFR in most locations. However,
with showers and storms moving northeastward onshore, conditions
likely to deteriorate in the next few hours. Post Tropical Cyclone
Arthur and its remnants will continue to bring impacts to the area
with rain and gusty winds through the night. The most impactful
weather will move through the area generally from 06Z to 15Z with
BTR/MSY/HDC/MCB targeted from 06Z to 12Z and ASD/NEW/GPT from 09Z
to 15Z. Brief periods of wind shear and gusts to 30+ knots will
accompany the strongest weather. Coverage of SHRA/TSRA will
diminish by late afternoon, as will the winds.

&&

.MARINE...
Issued at 1220 AM CDT Thu Jun 18 2026

Strong southerly winds of 20 to 25 knots with gusts of 30 knots
will remain in place over the coastal waters through tonight and
into Thursday and seas of 6 to 9 feet can be expected in the open
Gulf waters. Small craft advisories remain in effect due to these
conditions. Moving into the weekend and early next week, a broad
area of high pressure will build back over the eastern Gulf
waters. Persistent onshore winds of 10 to 15 knots and seas of 2
to 4 feet can be expected from Friday through early next week.

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Flood Watch through Friday morning for LAZ034>037-039-046>048-
     056>058-064-071-076>087-089-090-092-094-096-098>100.

GM...Small Craft Advisory until 6 AM CDT Friday for GMZ529-531>536-
     541-543-551-553-554-557-570-572-575-577.

MS...Flood Watch through Friday morning for MSZ068>071-077-083>088.

GM...Small Craft Advisory until 6 AM CDT Friday for GMZ531>536-541-
     543-551-553-554-557-570-572-575-577.

&&

SHORT TERM...RW
LONG TERM....RW
AVIATION...RW
MARINE...RW

Preliminary Local Storm Report
National Weather Service New Orleans LA
431 AM CDT Thu Jun 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 AM     Flash Flood      1 N Houma               29.59N 90.71W
06/18/2026                   Terrebonne         LA   Public

            Video on social media shows extensive street
            and yard flooding near Honduras Elementary
            School in Houma.

&&

PG

Preliminary Local Storm Report
National Weather Service New Orleans LA
502 AM CDT Thu Jun 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0451 AM     Marine Tstm Wind 13 NNE Metairie         30.18N 90.13W
06/18/2026  M46 MPH          GMZ531             LA   Mesonet

            The Weatherflow mesonet on the Lake
            Pontchartrain Causeway measured a
            thunderstorm wind gust of 46 mph.

&&

MEFFER

Preliminary Local Storm Report
National Weather Service New Orleans LA
528 AM CDT Thu Jun 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 AM     Flash Flood      1 NNW Raceland          29.73N 90.60W
06/18/2026                   Lafourche          LA   Public

            Video shows a home flooded with ankle deep
            water.

&&

PG

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Preliminary Local Storm Report
National Weather Service New Orleans LA
603 AM CDT Thu Jun 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 AM     Tstm Wnd Dmg     2 SE Metairie           29.97N 90.16W
06/18/2026                   Jefferson          LA   Broadcast Media

            Multiple broadcast media reported power
            flashes across Metairie area. Possible
            tornado.

&&

MEFFER

Preliminary Local Storm Report
National Weather Service New Orleans LA
611 AM CDT Thu Jun 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0530 AM     Flash Flood      3 SSE Destrehan         29.92N 90.34W
06/18/2026                   St. Charles        LA   Public

            Video of street flooding on Barton Avenue in
            Luling.

&&

PG