Small Craft Advisory 73, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
1205 AM CST Wed Dec 23 2020

.AVIATION...06z TAF issuance...Overall VFR conditions should
persist through the remainder of the night and likely through the
morning hours. Low clouds may fainlly begin to build in the
afternoon and some terminals will likely see MVFR cigs. The
greatest impacts will come from convection likely after 00z and
across the northwest first. The cold front will move through
tomorrow night and all terminals will deal with reduced vsbys and
lowered cigs as shra and tsra impact the entire area. After the
front moves through strong northwest winds will occur. /CAB/

&&

.PREV DISCUSSION... /issued 851 PM CST Tue Dec 22 2020/

UPDATE...Light winds, clear skies, and still relatively low
dewpoints have allowed much of the area to radiate rather quickly
this evening. Many locations have already approached forecast lows
for the night and will likely still fall another few degrees over
the next few hours but by midnight much of the area will probably
level off as LL winds become more southerly and dewpoints start to
creep up as better moisture advects in from the Gulf. Have already
update the forecast to show most locations reaching overnight lows
between now and 6z with temps holding steady and then slowly
rising before sunrise. Locations farther inland will likely see
temps still fall after midnight but even those locations should
stall before sunrise. /CAB/

PREV DISCUSSION... /issued Issued by National Weather Service
Lake Charles LA/

SHORT TERM...Tonight through Thursday Night
High pressure will continue to slide to the east with
southerly flow becoming established across the area
tonight and Wednesday. Temperatures will be a bit warmer
tonight with a light southerly flow and steadily increasing
low level moisture. There could be some patchy fog later
tonight but cloud cover should begin to enter the region
after midnight into Wednesday morning hours which should limit
radiational cooling factor.

On Wednesday a longwave trough moves into the central United
States with the base of the trough into south Texas. This scenario
will setup southwest winds aloft with weak impulses initially by
the afternoon hours. Increasing moisture and instability will also
aid in a few showers or isolated thunderstorms developing out
ahead of the main punch which is expected Wednesday evening into
Wednesday night when a cold front approaches and then sweeps
through the region around the early morning overnight hours.

There is a marginal risk for severe thunderstorms Wednesday 6 am
ending Thursday 6 am for all of southeast Louisiana and all of the
southern half of Mississippi. The Storm Prediction Center
indicates that marginal instability and lapse rates don't favor
widespread convection. However...along the frontal boundary...a
few cells may develop some rotation and therefore pose a marginal
risk for damaging winds and possibly a tornado.

The threat of severe weather will end Thursday with rain having
ended from west to east. High pressure will build back in with
dry northerly winds. Much colder air will settle in as well the
night before Christmas.

LONG TERM...Friday through Monday
On Christmas Day...colder air will settle into the area and remain
entrenched through much of Saturday. A upper level shortwave
trough will move into the Lone Star State of Texas Saturday with
low level southerly flow returning to our area. Rain chances enter
the picture once again Sunday night into Monday as the next cold
front sweeps into southeast Louisiana.

&&

.MARINE...
Onshore flow will increase tonight and Wednesday ahead of the next
storm system. Southeast between 15 and 20 knots can be expected on
Wednesday in advance of a strong cold front. In the wake of the
cold front, gale conditions are expected to develop over all of
the waters Wednesday night and persist through Thursday night.
Conditions will improve for Friday and Saturday as a high pressure
system moves across the Gulf South. Winds will decrease to
between 10 and 15 knots and seas will subside from 7 to 10 feet
Thursday down to 2 to 4 feet by Sunday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  38  48  27  48 /  90  10   0   0
BTR  38  47  29  50 /  80  10   0   0
ASD  39  50  28  51 / 100  20   0   0
MSY  43  49  34  50 / 100  20   0   0
GPT  42  50  31  48 / 100  40   0   0
PQL  42  52  28  49 /  90  50   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Gale Watch from late tonight through Thursday evening for GMZ530-
     532-534-536-538-550-552-555-557-570-572-575-577.

MS...None.
GM...Gale Watch from late tonight through Thursday evening for GMZ532-
     534-536-538-550-552-555-557-570-572-575-577.

&&