Small Craft Advisory 39, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
1258 PM CDT Mon Sep 26 2022

...New AVIATION...18Z TAF Package...Overall VFR conditions will
continue to fairly quiet. No impacts from cigs or vsbys but winds
could be a little breezy tomorrow and overnight along the south
side of the lake. Other than that no real impacts expected. /CAB/

&&

.SHORT TERM...
(Today through Tuesday)
Issued at 420 AM CDT Mon Sep 26 2022

Looks like our long awaited cold front is moving southward across
Mississippi and is almost to Interstate 20. There is an isolated
cluster of thunderstorms near Meridian Mississippi this morning
that currently looks like it will move into Alabama, but cannot
rule out the potential for development into our Mississippi
coastal counties around sunrise and will continue to monitor.
Temperatures at 3 AM CDT away from marine influences (warm water
temps), were in the upper 60s to mid 70s.

The cold front will be the main player across our area over the
next 36 hours, while most eyes are on recently upgraded Hurricane
Ian in the Caribbean, which appears to be targeting the Florida
Peninsula. It's expected to move into the southeast Gulf of Mexico
on Tuesday. The only effects we'll notice on land through Tuesday
may be a increase in wind speed Tuesday as the pressure gradient
between high pressure to our north and northwest and Ian tightens
somewhat.

The front will likely move through our area during the afternoon
hours today and be well off the coast Tuesday. Likely to see one
final day of high temperatures in the 90s for most of the area
today. Looking at forecast soundings, 925 mb temperatures on
Tuesday are expect to be 5-8C cooler than this afternoon, which
argues for high temperatures 10-15F cooler than Sunday. We've
been running above most deterministic guidance for highs for
several days, but the NBM has actually been doing pretty well with
that, and haven't strayed far from it today. Dew points near 70
today will be in the 40s and lower 50s by Tuesday afternoon. We
may eventually need to drop forecast highs for Tuesday another
degree or two, as we're at the upper end of the deterministic
numbers at present.

&&

.LONG TERM...
(Tuesday night through Sunday)
Issued at 420 AM CDT Mon Sep 26 2022

Regarding Hurricane Ian...it is still forecast to remain well
east of our local area and still looks unlikely that we will feel
any significant direct impacts from the storm. However, as it is
expected to be a large and strong storm, some indirect impacts are
accounted for in the local forecast. A tight pressure gradient
between surface high pressure to the north and Ian over the
eastern Gulf will set up for breezy to windy conditions Wednesday
and Thursday. We are currently carrying sustained winds generally
in the 15 to 25 mph range, especially on the Mississippi coast,
and expect gusty conditions in the afternoon as mixing brings
some stronger winds down from aloft. Winds around 850mb are
forecast to be around 35 mph, so we cannot rule out some gusts in
that range. May end up needing a wind advisory depending on how
things play out.

Again, we remind everyone that while it appears unlikely that Ian
will bring significant impacts to the area, it is forecast to be
a large storm and some impacts can extend well outside the cone.
We urge citizens in Southeast Louisiana and Coastal Mississippi to
continue monitoring the forecast for changes as a westward shift
could still result in some minor impacts across the local area.

As noted above, the main effects over the local area will be to
increase wind speeds somewhat on Wednesday and Thursday due to the
pressure gradient between Ian and high pressure to the north of
our area. This will also help to pull cool and dry air into the
area for much of the week. That will be a refreshing change from
the 90s of the last week. Any rain associated with Ian would
likely be limited to extreme eastern and southern portions of the
area Thursday and Friday, and that appears to be a low confidence
forecast at this time. Will generally ride with the NBM high
temperature forecast, but have tugged overnight lows downward
somewhat, especially north of Lake Pontchartrain in the normally
cooler areas where it may take the NBM a cycle or two to catch up.

&&

.MARINE...
Issued at 420 AM CDT Mon Sep 26 2022

Conditions will remain generally benign through the daytime hours
today with winds 10 knots or less and seas 2 ft or less. A cold
front will sweep through the coastal waters tonight and as high
pressure builds in behind it, expect winds and seas to increase.
Some of this will be a direct result of the front and some will be
a response to the tightening pressure gradient between the high
pressure behind the front and Hurricane Ian, which is forecast to
be in the eastern Gulf by tomorrow. Add in swells emanating from
the storm, and it's a pretty high confidence forecast of hazardous
conditions across the coastal waters for the Tuesday afternoon
through Friday time frame. The specific details are still a bit
in question and have currently forecast winds and seas near/below
30 knots and 12-15 feet respectively based on the current
forecast for Ian. But those with marine interests should keep a
close eye on the forecast as these details could change. Latest
forecast indicates headlines (Small Craft Advisory) probably will
be needed at some point during the day Tuesday onward. The latest
wind speed probabilities from NHC continue indicate less than a
20 percent chance of tropical storm conditions across extreme
southeastern portions of the coastal waters.

&&

.FIRE WEATHER...
Issued at 420 AM CDT Mon Sep 26 2022

Conditions that are conducive for the spread of fires are expected
on Wednesday. A dry air mass will be in place, and winds will
strengthen due to a tightening pressure gradient between high
pressure to the northwest and Hurricane Ian, which is forecast to
be a strong hurricane over the eastern Gulf of Mexico. Currently,
relative humidity is expected to drop to around 25 percent
Wednesday afternoon, and it could drop even lower as some guidance
continues to hint at potential for dewpoints about 2-4 degrees
lower than what is currently being carried in the forecast. Winds
are currently forecast to be sustained in the 15 to 25 kt range,
but with afternoon mixing, expect higher gusts. Combine these
factors with the fact that many areas haven't received appreciable
rain in a few weeks, and it is a situation that bears monitoring.
The area of greatest concern is likely to be over the Mississippi
coastal counties along Interstate 10 where rainfall over the last
month has been around 25 percent of normal.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  52  79  54  78 /   0   0   0   0
BTR  57  84  58  83 /   0   0   0   0
ASD  57  84  57  82 /   0   0   0   0
MSY  66  84  64  81 /   0   0   0   0
GPT  59  84  58  82 /   0   0   0   0
PQL  58  84  60  81 /   0   0   0   0

&&

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