Flash Flood Warning 76, NWS New Orleans, LA

323 
WGUS74 KLIX 142244
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
444 PM CST Wed Dec 14 2022

LAC063-091-103-105-117-MSC109-147-142254-
/O.EXP.KLIX.FF.W.0076.000000T0000Z-221214T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Livingston LA-St. Helena LA-St. Tammany LA-Tangipahoa LA-Washington
LA-Pearl River MS-Walthall MS-
444 PM CST Wed Dec 14 2022

...FLASH FLOOD WARNING WILL EXPIRE AT 445 PM CST THIS AFTERNOON FOR 
NORTHEASTERN LIVINGSTON, SOUTHEASTERN ST. HELENA, NORTHWESTERN ST. 
TAMMANY, TANGIPAHOA AND WASHINGTON PARISHES AND WESTERN PEARL RIVER 
AND SOUTH CENTRAL WALTHALL COUNTIES...

The heavy rain has ended. However, high water will take time to 
runoff. Please continue to heed remaining road closures.

A Flood Watch remains in effect until 900 PM CST for portions of 
southeast Louisiana and southern Mississippi.

LAT...LON 3101 9018 3100 8969 3032 9043 3034 9049
      3055 9079

$$

JFL

Area Forecast Discussion
National Weather Service New Orleans LA
633 AM CST Wed Dec 14 2022

...New UPDATE, AVIATION...

.UPDATE...
Issued at 619 AM CST Wed Dec 14 2022

Zone forecast updated for Tornado Watch 587 through 19z mainly
north and west of Lake Pontchartrain, which does NOT include New
Orleans metro area at this time. We do anticipate watches during
the afternoon hours, so areas not currently in the watch should
not let their guard down today.

May not see a lot of eastward progress of the line of
thunderstorms over the next couple of hours while we wait for the
shortwave over Texas to approach the area. This could allow areas
to the southeast to destabilize more than previously forecast.
Still potential for low pressure to develop to our north, which
would back surface winds somewhat, enhancing tornado potential. A
very quick look at the lower levels of the 12z LIX upper air
sounding continues to show sufficient shear and instability for
severe weather although locally, moisture levels dropped slightly
from the 00z sounding (1.45 to 1.25). Expect that to recover over
the next few hours.

&&

.SHORT TERM...
(Today through Thursday)
Issued at 417 AM CST Wed Dec 14 2022

Main forecast issues for the entire forecast package occur in the
first 18 hours of the forecast...today and this evening.
Significant severe weather and excessive rainfall threats,
especially from the Interstate 10 corridor northward.

Stacked deep upper low centered over Nebraska early this morning
with one shortwave rotating around the low near Kansas City, and a
second near the Texas-New Mexico border. Some weak hints of a
meso-low trying to develop over the Mississippi Delta north of
Vicksburg along the occlusion. A nearly solid line of convection
extended from northeast Mississippi to near Jackson to Lake
Charles at 3 AM CST, just now entering the northwest corner of our
CWA. Ahead of the convection, the entire area is in the warm
sector with temperatures 70-75F and dew points upper 60s and lower
70s. Soundings are plenty supportive of severe weather with MUCAPE
values of 1500 J/kg or greater, 0-1km SRH of 250 m2/s2, shear near
50 knots and precipitable water values around 1.50 inches. Current
line of convection may not make much more eastward progress over
the next 3 to 6 hours, until the Texas-New Mexico shortwave lifts
northeastward toward the middle Mississippi River Valley. Current
Tornado Watch 586 for northwest portions of our area likely to be
replaced around 12Z. There have been multiple tornado warnings to
our north and west overnight, and as the shortwave lifts
northeast that may back surface winds a bit more, making the
situation even more conducive for tornadic development. There may
be multiple rounds of thunderstorms, producing 2 inch/hour
rainfallrates today. Widespread 2-4 inch rainfall amounts likely,
and can't rule out spot max totals exceeding 6 inches. Current
Flood Watch looks fine. System is expected to become more
progressive later this afternoon/evening, so an eastward expansion
into Harrison and Jackson Counties along the Mississippi coast
may not be necessary.

Current indications are that convection should move east of the
Mississippi coast by mid evening (9 PM or so), with cooler and
drier air behind it.

There's been some very minor coastal inundation in Hancock County
at high tide early this morning with the southeasterly winds.
Water should subside somewhat later this morning, and wind shift
to northwest should occur several hours prior to the main high
tide cycle tonight, so no current plans for a coastal flood
advisory. Day shift may also need to assess potential Wind
Advisory if pressure gradient tightens very much.

Thursday will be cooler/drier/sunny with highs probably only
60-65.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 417 AM CST Wed Dec 14 2022

A fast moving shortwave will move along the zonal flow across the
area on Saturday. Still a split between the GFS and ECMWF
solutions whether any significant moisture will exist over land.
Can't rule out a light precipitation event along the coast
during the day on Saturday with the emphasis on light amounts.
Beyond that system, quite a bit of disagreement between the
globals on shortwaves moving through the zonal flow, with the GFS
being quicker than the ECMWF. This could bring precipitation back
into the area as early as Monday afternoon/night.

At this point, any subfreezing temperatures Sunday morning would
occur well after precipitation ends, so no threat of wintry
precipitation with that event. Spread in forecast temperature
guidance from Sunday through Tuesday is fairly small, so no
significant adjustments made from NBM on highs. For overnight
lows, went closer to the 25th percentile of NBM.

With holiday travel occurring just beyond the forecast period,
would note that there is a LARGE spread in forecast solutions as
we approach Christmas with significant differences in where a cold
air mass will be. The GFS solutions focus the cold air over the
Mississippi River Valley, with the ECMWF solutions focusing on New
England. By the end of next week, 18z 2 meter temperatures in the
ensemble means have differences of 20F or greater. Any confidence
in a particular forecast solution should be considered low.

&&

.AVIATION...
(12Z TAFS)
Issued at 619 AM CST Wed Dec 14 2022

Current conditions range from IFR northwest to VFR southeast.
Likely to be direct impacts from TSRA at all terminals at some
point during the daytime hours with IFR or lower visibilities and
perhaps ceilings. Have tried to provide a 2-3 hour window of TEMPO
conditions with TSRA but these may need adjusted. Certainly could
see gradient wind gusts to 25-30 knots outside of convection at
most terminals today. Cold front passage during the late afternoon
and evening hours will end threat of TSRA, with eventual
improvement of ceilings/visibilities to VFR after 06z Thursday.

&&

.MARINE...
Issued at 417 AM CST Wed Dec 14 2022

Will continue Small Craft Advisory today, with wind shift
occurring tonight. Much of the forecast period will have some sort
of hazardous weather headlines over at least the open waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  72  42  60  35 / 100  20   0   0
BTR  75  44  63  38 / 100  10   0   0
ASD  79  46  65  37 / 100  60   0   0
MSY  78  51  63  47 /  90  50   0   0
GPT  76  48  65  39 /  90  90   0   0
PQL  76  47  63  37 /  80 100   0   0

&&

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

GM...Small Craft Advisory until 6 AM CST Thursday for GMZ530-532-534.

     Small Craft Advisory until 6 AM CST Thursday for GMZ536-538-550-
     552-555-557-570-572-575-577.

MS...Flood Watch through this evening for MSZ068>071-077-080.

GM...Small Craft Advisory until 6 AM CST Thursday for GMZ532-534.

     Small Craft Advisory until 6 AM CST Thursday for GMZ538-550-552-
     555-557-570-572-575-577.

&&

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1002 AM CST WED DEC 14 2022

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

1000 AM     FLASH FLOOD      1 E CROSBY              31.28N 91.05W
12/14/2022                   AMITE              MS   LAW ENFORCEMENT

            CARS FLOODED AND WATER IN HOMES IN CROSBY.

&&

JZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1040 AM CST WED DEC 14 2022

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

1000 AM     FLASH FLOOD      3 NNE FORT ADAMS        31.13N 91.52W
12/14/2022                   WILKINSON          MS   PUBLIC

            IMPASSIBLE ROAD FLOODING ALONG LAKE MARY RD.
            FLOODING NEAR HWY 24 AND PERCY CREEK SAND
            RD.

&&

JZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1241 PM CST WED DEC 14 2022

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

1159 AM     TORNADO          3 WSW DONALDSONVILLE    30.07N 91.05W
12/14/2022                   ASCENSION          LA   PUBLIC

            SPOTTER CONFIRMS TORNADO TOUCHED DOWN WEST
            OF DONALDSONVILLE.

&&

JZ