Special Weather Statement, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
1202 AM CDT Tue Jun 20 2023

...New UPDATE, AVIATION...

.UPDATE...
Issued at 1153 PM CDT Mon Jun 19 2023

Cleared several counties/parishes from the Severe Thunderstorm
Watch earlier. At present, looks like we'll allow the remainder to
expire at 1 AM CDT as storms have been weakening. Outflow from the
storms is still very capable of producing wind gusts to 40-50 mph
over the next hour or two. No changes to Flash Flood Watch at this
time. Certainly saw areas of 2-4 inches of rain in 60-90 minutes,
and overall airmass isn't changing much in moisture content. Most
precipitation should die out in the next couple hours, but expect
a redevelopment of showers/storms between 10 AM and noon. Mid
shift will take another look at things and can't rule out
adjustments to the watch.

&&

.UPDATE...
Issued at 659 PM CDT Mon Jun 19 2023

Issued Flash Flood Watch a little while ago through 7 PM CDT
tomorrow for much of the area. Admittedly, confidence in specifics
is not particularly high, but considering what's occurred in areas
to the east over the last few days, and even over Jackson County
today, it's the path of least regret.

As has been said, it's a conditional situation with potential for
a high impact event. We can see on radar outflow moving westward
toward the Pearl River and St. Bernard Parish with thunderstorms
firing to the east of the boundary. These storms have been
producing hail and very heavy rainfall. Convection allowing models
keep producing storms through late evening, and then fire more
off on Tuesday morning. Multiple reports of 4-7 inches of rain
over Jackson County this afternoon. The question has been how far
westward to carry the watch, but with the upper ridge retreating
somewhat on Tuesday, opted to carry it westward to the Mississippi
River. Adjustments are likely to be made overnight to exclude some
portions of the area based on eventual evolution of convection, as
some portions of the area may end up with little or no
precipitation.

&&

.SHORT TERM...
(This evening through Tuesday night)
Issued at 350 PM CDT Mon Jun 19 2023

A fairly active afternoon/evening is expected across portions of the
CWA in terms of heavy rainfall potential. In the upper levels, a
very amplified ridge axis extends across the entire midsection of
the country stretching from the Rio Grande to well past the Great
Lakes. East of there, a deepening low has become cutoff near the
Ohio River Valley. A weak but significant surface boundary lies
between those large scale features near the LIX and MOB border along
the MS/AL coastline. The 12Z LIX sounding showed ample moisture
throughout the column outside of a little drying in the mid levels.
More concerning is the extremely steep lapse rates above the
850mb height. 7-8C/KM, and probably steeper now, is very rare for
this time of year. But that's just one aspect of ongoing very
robust convection in coastal AL thats spreading west into coastal
MS. The existence of the nearly stalled boundary continues to be a
major focal point of development and resulting in what will be
continued training of thunderstorms. Additionally, strong southern
flow noted on MOB's radar areal surface obs indicate a meso low
is potentially developing near the MS/AL border. This has been and
will continue to enhance precip development and efficiency.
Upwards of 5 to 10 inches of rain has fallen in Baldwin County AL
today and numbers in that realm are certainly possible on the MS
Coast. Weaker tornadoes will be possible as well as mesoscale
local environments in the vicinity of the boundary create an
environment with increased shear and helicity. This is similar to
what occurred yesterday along the I- 10 Twins Span bridge between
New Orleans East and Slidell.

Moving into the late evening and overnight, CAMs suggest a line of
storms will potentially develop roughly along a line from Baton
Rouge to New Orleans. Its not clear if this will be a new line that
initiates along 80 dewpoint line or just the current line in MS that
is driven southwestward by convection over time. Either way, will
once again be looking at the possibility of flash flooding and an
isolated tornado or 2.

Going into Tuesday, the shear axis between ridge to the west and
trough/low to the east will remain active. CAMs and medium range
models are all pinging on numerous showers and storms, but moreso
along BR/NOLA line instead of coastal/SW MS as it has been over the
last few days. Flash Flood Watch did cross my mind, but wasn't
confident enough to go with one that far out due to uncertainty.
Until that convection does develop, it'll still be hot although not
as hot has it has been. With the upper low to the east nudging
southwestward, temps will not be able to warm as much as previous
days. Thus, will not be reissuing the Excessive Heat Warning for any
zones but will send out another Heat Advisory (for a trimmed down
area).

&&

.LONG TERM...
(Tuesday night through Sunday)
Issued at 343 AM CDT Mon Jun 19 2023

The stacked nature of these features(high and low) will also be
reflected at the sfc and will begin to send a front, although very
weak, into the area by Tuesday night into Wed. This will be a slow
process though. And while this boundary transits the area slowly,
training of storms could occur Tuesday and again Wed. These could
also last well into the evening hours each day. The front looks to
be over the gulf before stalling late Wed. This will take most of
this activity to that area as well. Dew pt temps look to cool back
to the upper 60s lower 70s by Wed night and temps look to cool also
into the lower 70s north(maybe even a 69F for MCB) to mid/upper 70s
south by Wed night. Another dry air surge will move in Fri keeping
storms over the coastal areas and offshore. This dry air surge will
be from the last short wave moving through the base of the upper
trough allowing this feature to begin moving north then NE. The
migration of this upper low looks to start late Wed night into
Thursday. But the main shift northward occurs as this short wave
moves to the east side of the trough Thu night into Friday. This
will cause the dew pt gradient to begin shifting to the NW bringing
back the deep moisture by the weekend. An easterly wave will move
through the gulf over the weekend providing moisture with a more
normal summer distribution of sh/ts. But the H7 high will have
ridged into the area as the upper trough departs, a hostile
environment will remain over the gulf as this easterly wave moves
through. Now, the good part of this is 2 fold. The first is less
severe storms by late Wed into Thu and possibly Fri, but we will
take this a day at a time. The second is the heat wave may get
broken and could be as early as Tuesday. The conditions will be
similar Tue but sine the trough will be over the area, it will bring
a lot more cloud cover keeping temps lower and as the relatively
dry air moves in, it could also keep the heat wave down Wed
through Friday. Maybe the Heat advisory now and again but the
excessive heat warnings may be going away at least for a short
while. By the way, the only normal thing in this fcast is the
easterly wave for this time of year. We get heat waves in June,
but it is not common to see them to this degree this early, these
usually come in July and August. And NW flow this long is insane.
And eventually, the H7 high will plant itself right over our area
by next week. But that's a ways out still. This migration of the
stacked high over Mexico is quite normal as it should eventually
find itself over the SW. And it is this process that causes the
NAMS(North American Monsoon System) to occur as it brings deep
moisture out of the Pacific into the SW on the western periphery
of the high. This is a normal process as well and if it carries
out like it should, then this heat will eventually subside here
and move west until the stacked high moves east, which is normally
does in late July/August. This high may be a lot more expansive
for this time of year, which is something worth looking into.

&&

.AVIATION...
(06Z TAFS)
Issued at 1153 PM CDT Mon Jun 19 2023

Convection has shifted west of KMCB, KGPT and KASD for now, but
could still impact remaining terminals for the first couple hours
of the new package. Western terminals could see wind gusts to 35
knots with the outflow from the convective line. MVFR conditions
likely for several hours around sunrise, then redevelopment of
convection is likely by late morning somewhere in the local area,
but little confidence in exactly where it will start firing. Will
use VCTS for now, but later packages should be able to narrow down
threat some more. Precipitation looks to end after sunset as
slightly drier air moves into the area.

&&

.MARINE...
Issued at 343 AM CDT Mon Jun 19 2023

A broad ridge of surface high pressure centered over the southern
and eastern Gulf will continue to produce southwest flow of 10 to 20
knots over the coastal waters through Tuesday. Heading into
Wednesday and Thursday, a weak frontal boundary will slip into the
waters and stall. This will lead to weak northerly and easterly flow
of 10 knots or less during this period time. By the end of the week,
the boundary is expected to weaken and move NW, and a return to
prevailing onshore flow of 10 to 15 knots is expected as the surface
ridge over the southern and eastern Gulf once again becomes more
dominant.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  72  91  72  91 /  70  70  40  50
BTR  77  95  78  94 /  50  80  50  60
ASD  71  93  76  92 /  70  80  60  70
MSY  77  94  79  91 /  50  80  60  80
GPT  71  90  75  89 /  60  80  60  70
PQL  71  93  73  91 /  40  60  50  70

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Flood Watch through Tuesday evening for LAZ034>037-039-046>048-
     056>060-064-065-069>071-076>090.

     Heat Advisory from 11 AM to 7 PM CDT Tuesday for LAZ034-035-
     046>048-056>060-064>070-076>090.

GM...None.
MS...Flood Watch through Tuesday evening for MSZ068>071-077-083>088.

GM...None.
&&

SHORT TERM...ME
LONG TERM....TE
AVIATION/UPDATE...RW
MARINE...TE

Special Weather Statement
National Weather Service New Orleans LA
1101 PM CDT Mon Jun 19 2023

LAZ037-071-081-083-200445-
Central Tangipahoa LA-Northern Livingston LA-St. Helena LA-
Northern Tangipahoa LA-
1101 PM CDT Mon Jun 19 2023

...A strong thunderstorm will impact portions of southeastern St.
Helena, northeastern Livingston and central Tangipahoa Parishes
through 1145 PM CDT...

At 1101 PM CDT, Doppler radar was tracking a strong thunderstorm near
Independence, or 7 miles south of Amite, moving south at 15 mph.

HAZARD...Wind gusts up to 50 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Hammond, Amite, Amite City, Independence, Roseland, Albany,
Montpelier, Natalbany, Robert and Tickfaw.

This includes Interstate 55 in Louisiana between mile markers 31 and
50.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 100 AM CDT for
southeastern Louisiana.

&&

LAT...LON 3077 9073 3077 9051 3051 9025 3048 9065
TIME...MOT...LOC 0401Z 343DEG 12KT 3063 9056

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

CAB

Preliminary Local Storm Report
National Weather Service New Orleans LA
1104 PM CDT Mon Jun 19 2023

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

0954 PM     Tstm Wnd Dmg     1 SE Lacombe            30.30N 89.92W
06/19/2023                   St. Tammany        LA   Fire Dept/Rescue

            Report of a tree down on a mobile home.

&&

HRL

Preliminary Local Storm Report...Summary
National Weather Service New Orleans LA
1114 PM CDT Mon Jun 19 2023

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

0855 PM     Hail             3 W Picayune            30.53N 89.73W
06/19/2023  M1.00 inch       Pearl River        MS   Public

0250 PM     Tornado          2 SSW Moss Point        30.40N 88.54W
06/19/2023                   Jackson            MS   Storm Chaser

            Tornado confirmed by video/picture near Moss
            Point, MS.

0255 PM     Tornado          2 S Moss Point          30.40N 88.53W
06/19/2023                   Jackson            MS   Emergency Mngr

            Emergency manager reports numerous trees
            damaged, power lines downed, and damage to
            houses and commercial buildings in Moss
            Point.

0345 PM     Rain             2 SE Escatawpa          30.46N 88.53W
06/19/2023  M5.01 inch       Jackson            MS   ASOS

            ASOS station KPQL Pascagoula Trent Lott
            Intl. Rainfall total since 6:30 AM.

0350 PM     Rain             6 E Moss Point          30.44N 88.43W
06/19/2023  M7.49 inch       Jackson            MS   Mesonet

            Mesonet station GRBM6 Grand Bay.

0415 PM     Rain             5 N Gautier             30.46N 88.63W
06/19/2023  M6.89 inch       Jackson            MS   Mesonet

            Rainfall since 644 AM CDT.

0419 PM     Rain             5 E Escatawpa           30.49N 88.47W
06/19/2023  M7.51 inch       Jackson            MS   Mesonet

            Rainfall since 6:30 AM.

0452 PM     Tstm Wnd Gst     2 WNW Biloxi            30.41N 88.92W
06/19/2023  M44 MPH          Harrison           MS   AWOS

            Keesler Air Force Base measured a wind gust
            of 44 mph.

0715 PM     Tstm Wnd Gst     56 E Venice             29.25N 88.43W
06/19/2023  M49 MPH          GMZ577             LA   AWOS

            AWOS station KVKY Main Pass 289C.

0835 PM     Tstm Wnd Gst     56 E Venice             29.25N 88.43W
06/19/2023  M46 MPH          GMZ577             LA   AWOS

            AWOS station KVKY Main Pass 289C.

0850 PM     Tstm Wnd Gst     68 E Venice             29.21N 88.23W
06/19/2023  M40 MPH          GMZ577             LA   Mesonet

            Mesonet station 42040 70 S Sand Island.

0948 PM     Tstm Wnd Gst     1 SSW Mandeville        30.36N 90.09W
06/19/2023  M47 MPH          GMZ530             LA   Mesonet

            Mesonet station XMVL Mandeville.

0951 PM     Tstm Wnd Gst     12 SSW Mandeville       30.20N 90.12W
06/19/2023  M43 MPH          GMZ530             LA   Mesonet

            Mesonet station XPTN Pontchartrain Causeway.

0956 PM     Tstm Wnd Gst     12 SSW Mandeville       30.20N 90.12W
06/19/2023  M50 MPH          GMZ530             LA   Mesonet

            Mesonet station XPTN Pontchartrain Causeway.

1006 PM     Tstm Wnd Gst     12 SSW Mandeville       30.20N 90.12W
06/19/2023  M55 MPH          GMZ530             LA   Mesonet

            Mesonet station XPTN Pontchartrain Causeway.

0430 PM     Tstm Wnd Gst     11 SSE Pascagoula       30.21N 88.50W
06/19/2023  M65 MPH          GMZ532             MS   C-Man Station

            Petit Bois Island recorded a wind gust of 65
            mph.

0430 PM     Tstm Wnd Gst     1 NNE Bay Saint Louis   30.32N 89.33W
06/19/2023  M50 MPH          GMZ532             MS   Buoy

            Corrects previous tstm wnd gst report from 1
            NNE Bay Saint Louis. Bay Waveland Yacht Club
            measured a wind gust of 50 mph.

0439 PM     Hail             1 SW Pass Christian     30.31N 89.25W
06/19/2023  E2.00 inch       GMZ532             MS   Public

            Picture sent on social media of
            approximately 2 inch diameter hail near Pass
            Christian Harbor. Time estimated by radar.

0641 PM     Tstm Wnd Gst     12 SSE Gulfport         30.23N 88.98W
06/19/2023  M71 MPH          GMZ532             MS   Mesonet

            Mesonet station XSHI Ship Island, sustained
            45 mph gusting 71 mph.

0954 PM     Tstm Wnd Dmg     1 SE Lacombe            30.30N 89.92W
06/19/2023                   St. Tammany        LA   Fire Dept/Rescue

            Report of a tree down on a mobile home.

1018 PM     Flash Flood      1 ENE Slidell           30.28N 89.76W
06/19/2023                   St. Tammany        LA   Fire Dept/Rescue

            Cars stalled in flood water on Gause
            Boulevard in front of Hobby Lobby.

0824 PM     Tstm Wnd Gst     2 NNE Yscloskey         29.87N 89.67W
06/19/2023  M40 MPH          St. Bernard        LA   Buoy

            Buoy station SHBL1 Shell Beach, LA.

0936 PM     Tstm Wnd Gst     2 NNE Yscloskey         29.87N 89.67W
06/19/2023  M47 MPH          St. Bernard        LA   Buoy

            Buoy station SHBL1 Shell Beach, LA.

1024 PM     Tstm Wnd Gst     2 NNE Yscloskey         29.87N 89.67W
06/19/2023  M58 MPH          St. Bernard        LA   Buoy

            Buoy station SHBL1 Shell Beach, LA.

0908 PM     Tstm Wnd Gst     5 SSE East New Orleans  30.00N 89.90W
06/19/2023  M64 MPH          Orleans            LA   Mesonet

            Mesonet station XBYU Bayou Bienvenue
            (Vertical Lift).

0938 PM     Tstm Wnd Gst     5 SSE East New Orleans  30.00N 89.90W
06/19/2023  M65 MPH          Orleans            LA   Mesonet

            Mesonet station XBYU Bayou Bienvenue
            (Vertical Lift).

0947 PM     Tstm Wnd Gst     6 WSW East New Orleans  30.04N 90.03W
06/19/2023  M47 MPH          Orleans            LA   ASOS

            ASOS station KNEW New Orleans Lakefront
            Airport.

1000 PM     Tstm Wnd Gst     2 NNW Gretna            29.94N 90.06W
06/19/2023  M52 MPH          Orleans            LA   Mesonet

            Mesonet station 1970W Port Nola
            Administration - Wareh.

1010 PM     Tstm Wnd Gst     3 S East New Orleans    30.02N 89.93W
06/19/2023  M53 MPH          Orleans            LA   Mesonet

            Mesonet station 1872W Municipal Training
            Academy East.

&&

Special Weather Statement
National Weather Service New Orleans LA
1140 PM CDT Mon Jun 19 2023

LAZ036-037-046>048-056-057-059-065-066-083-085-200530-
Lower Terrebonne LA-Iberville LA-Northern Livingston LA-
Upper Terrebonne LA-St. Helena LA-East Feliciana LA-
Western Ascension LA-Assumption LA-West Baton Rouge LA-St. James LA-
Upper Lafourche LA-East Baton Rouge LA-
1140 PM CDT Mon Jun 19 2023

...Strong winds assocaited with a large outflow boundary coming from
the severe storms earlier to the east will impact portions of
western Ascension, west central St. James, West Baton Rouge,
southwestern St. Helena, northwestern Terrebonne, northwestern
Livingston, southwestern East Feliciana, Iberville, northwestern
Lafourche, East Baton Rouge and Assumption Parishes through 1230 AM
CDT...

At 1138 PM CDT, we have had multiple reporting sistes report wind
gusts in excess of 40 mph. This boundary is a line extending from 8
miles northeast of Watson to near Shenandoah to near Geismar to
Paincourtville to near Labadieville to near Gray. Movement was west
at 25 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Public.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Baton Rouge, Houma, Zachary, Baker, Denham Springs, Gonzales,
Donaldsonville, Plaquemine, Port Allen, Napoleonville, Oak Hills
Place, St. Gabriel, Walker, Addis, Brusly, White Castle, Slaughter,
Westminster, Schriever and Geismar.

This includes the following Interstates...
 Interstate 10 in Louisiana between mile markers 144 and 180.
 Interstate 12 between mile markers 1 and 17.
 Interstate 110 in Louisiana between mile markers 1 and 8.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3071 9128 3072 9079 3041 9084 3023 9091
      2999 9094 2979 9086 2958 9071 2949 9122
      2954 9126 2958 9123 2963 9108 2965 9111
      2981 9110 2986 9120 2997 9126 3004 9122
      3006 9137 3010 9138 3010 9146 3019 9147
TIME...MOT...LOC 0438Z 086DEG 23KT 3064 9083 3041 9093 3023 9099 2999
9103 2979 9094 2964 9084

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

CAB

Special Weather Statement
National Weather Service New Orleans LA
1210 AM CDT Tue Jun 20 2023

LAZ058-060-087-200600-
St. Charles LA-St. John The Baptist LA-Upper Jefferson LA-
1210 AM CDT Tue Jun 20 2023

...A strong thunderstorm will impact portions of central St. John The
Baptist, northern St. Charles and northwestern Jefferson Parishes
through 100 AM CDT...

At 1209 AM CDT, Doppler radar was tracking a strong thunderstorm near
Norco, or near Laplace, moving south at 30 mph.

HAZARD...Wind gusts up to 50 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Hahnville, Avondale, Laplace, Metairie, Jefferson, Harahan, Westwego,
Norco, Elmwood, Montz, Luling, River Ridge, Boutte, Ama, Destrehan,
Waggaman, Taft, New Sarpy, St. Rose and Paradis.

This includes the following Interstates...
 Interstate 10 in Louisiana between mile markers 209 and 225.
 Interstate 55 in Louisiana between mile markers 1 and 6.
 Interstate 310 between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 100 AM CDT for
southeastern Louisiana.

&&

LAT...LON 2988 9049 3018 9045 3018 9039 3012 9039
      3010 9037 3007 9024 2989 9015 2989 9016
      2987 9017
TIME...MOT...LOC 0509Z 353DEG 26KT 3008 9037

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

CAB

Special Weather Statement
National Weather Service New Orleans LA
1229 AM CDT Tue Jun 20 2023

LAZ077-087-200600-
Western Orleans LA-Upper Jefferson LA-
1229 AM CDT Tue Jun 20 2023

...A strong thunderstorm will impact portions of southwestern Orleans
and northwestern Jefferson Parishes through 100 AM CDT...

At 1229 AM CDT, Doppler radar was tracking a strong thunderstorm over
Metairie, moving southeast at 40 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
New Orleans, Metairie, Harvey, Timberlane, Marrero, Avondale,
Jefferson, Gretna, Harahan, Westwego, Elmwood, Terrytown, Bridge
City, River Ridge, Waggaman, Arabi, Ama, St. Rose, New Orleans
Armstrong Airport and Lakefront Airport.

This includes the following Interstates...
 Interstate 10 in Louisiana between mile markers 222 and 243.
 Interstate 610 between mile markers 1 and 4.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 100 AM CDT for
southeastern Louisiana.

&&

LAT...LON 2994 9028 3006 9029 3008 9027 3008 9026
      3006 9006 3008 8999 2987 9002
TIME...MOT...LOC 0529Z 298DEG 34KT 2998 9017

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

CAB