Area Forecast Discussion
Issued by NWS Lake Charles, LA

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000
FXUS64 KLCH 270359
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
1059 PM CDT Mon Oct 26 2020

.UPDATE...
Only minor changes to hourly temps and dewpoints to reflect
observations this evening. Warm and muggy conditions persist acrs
the area with temperatures in the upper 60s to lower 70s. Sfc low
pres is noted over E TX, with a frontal boundary extending
northeast acrs N LA and southwest acrs SE TX. Northwest of the
front, much colder air is spilling into TX, with temperatures in
the 50s from Huntsville to College Station, and 30s further back
acrs N TX. The front is not expected to move much overnight, so
expect abnormally warm conditions to continue with lows only
falling into the lows to middle 60s.

Meanwhile, Hurricane Zeta is approaching the Yucatan Peninsula and
will be crossing the land mass overnight, then emerging into the
southern Gulf of Mexico Tuesday. The latest NHC fcst has changed
little, with the hurricane approaching the SE LA coast on
Wednesday.

24

&&

.PREV DISCUSSION... /issued 631 PM CDT Mon Oct 26 2020/

DISCUSSION...
00Z OCT 27 TAF PACKAGE

AVIATION...

Current VFR conditions to continue into the night. Ceilings
lowering to MVFR starting tomorrow morning. Winds will be
relatively light out of the ENE and NE.
Stigger/87

PREV DISCUSSION... /issued 510 PM CDT Mon Oct 26 2020/

SYNOPSIS...
Watching Hurricane Zeta and any potential impacts, mainly for the
far eastern portion of the forecast area, through Wednesday evening.
A cold front early on Thursday will bring a dry continental airmass
into the forecast area that will give a definite feeling of Fall
through the Halloween weekend into early next week and Election Day.

Rua

DISCUSSION...
Clouds have been slow to erode today with some southerly winds
aloft bringing a bit of overriding moisture. High pressure across
the area will further weaken tonight with cloud cover increasing
again during the overnight.

All eyes will then focus on Hurricane Zeta, and a powerful upper
level low over the southwest US.

With favorable conditions, Zeta has strengthened into a Hurricane
and has started to move off to the northwest around an upper level
sub-tropical ridge east of Florida.

With the extra upper air sounding data across the southeast US
and data from Gulfstream flights, both global, regional, and
consensus models are coming into better agreement with Zeta. Zeta
is expected to get pick up by the increasing deep southwest flow
ahead of the upper level low with the center making landfall
somewhere along the south central or southeast Louisiana coast
between Morgan City and the Mouth of the Mississippi River
Wednesday Evening.

Although increasing strong upper level shear and cooler shelf
waters would tend to promote weakening, the system has a
probability of making landfall as a Category One wind scale
hurricane.

All indications are that this hurricane will not be large in size,
and with the strong southwest shear, should begin to be
asymmetric as it nears the coast, therefore, the stronger impacts
should be east of the center, with a tight gradient of lessening
impacts off to the west.

Deterministic wind profiles do not show sustained tropical storm
force winds over land areas, however probabilities for lower
Acadiana are above 30 percent, and that potential, along with
gusts to tropical storm force, has prompted the issuance of a
Tropical Storm Watch along the coast east of Intracoastal City.
Besides the parishes along the coast, added Lower St. Martin
Parish to the Tropical Storm Watch.

The same area along the coast has a Storm Surge Watch for the
potential of 2 to 4 feet inundation. Again, if the track stays as
it is or shifts further to the east, then that area will receive
mainly offshore flow and the risk will for storm surge will be
reduced and the decision to upgrade to a warning or not will
likely come tomorrow morning.

Again, with the asymmetric look, and drier air moving rapidly
into the region, the heavy rain and QPF gradient will be likely be
large with 1 to 3, possibly 4 inches for the lower Atchafalaya
Basin to 1 inch or less elsewhere. Areas further to the west,
including southwest Louisiana and southeast Texas will likely get
more rainfall from the front boundary than the tropical moisture.

The good news will be that from Thursday onward a series of high
pressure systems up north with ridge down into the forecast area
providing a prolonged episode of a dry continental air mass. This
will provide nice fall weather into the weekend and early next
week.

Rua

MARINE...
Weak surface ridge across the northern Gulf of Mexico will continue
to weaken tonight into Tuesday with mainly light to modest easterly
flow. Easterly winds will increase later on Tuesday into Tuesday
night as Zeta moves through the southern and central Gulf of Mexico.

Hurricane Zeta is then expected to move toward the south central to
southeast Louisiana coast on Wednesday into Wednesday evening.
Currently, deterministic wind forecast has tropical storm force
winds reaching eastern sections of GMZ475, marine zone between
Intracoastal City and the Lower Atchafalaya River beyond 20 nm on
Wednesday morning, then spread into GMZ455 during the day, with
tropical storm winds ending during Wednesday evening. Hurricane
wind probabilities are high enough that marine zone GMZ475 was
placed under a Hurricane Watch, although deterministic wind field
keeps the hurricane force winds just to the east.

A cold front will move in behind the departing tropical cyclone on
Thursday with brisk northerly winds. These offshore winds will begin
to decrease by Friday as high pressure settles into the region.

Rua

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  60  79  66  78 /   0  40  50  80
LCH  65  81  70  80 /   0  40  50  70
LFT  66  83  73  82 /   0  50  60  80
BPT  67  81  70  79 /  10  40  40  50

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...Tropical Storm Watch for LAZ052>055.

     Storm Surge Watch for LAZ052>054.

TX...None.
GM...Hurricane Watch for GMZ475.

     Tropical Storm Watch for GMZ435-455.

&&

$$

PUBLIC...24



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