Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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FXUS64 KLIX 222045
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
245 PM CST Wed Nov 22 2017

.SHORT TERM...

Deep layer northwest flow will remain in control of
the area through Friday night. This flow pattern will keep a very
dry and very stable airmass in place across the region. Subsidence
throughout the atmospheric column combined with the already dry
airmass will keep skies clear through Friday night. The northwest
flow regime will also advect in a cooler airmass through the
period, and expect temperatures to be around 10 degrees below
average for Thanksgiving Day and 5 degrees below average on
Friday. The clear skies and light winds expected tonight and
tomorrow will also allow for strong radiational cooling to occur.
As a result, lows should fall into the 30s in most locations both
nights. Only areas immediately south of Lake Pontchartrain and
close to the Louisiana coast will remain the low to mid 40s
tonight and tomorrow night. Some modification in temperatures is
expected Friday night as the heart of the 925mb cold pool shifts
to the east, but lows should still be a good 5 degrees below
average in the upper 30s and lower 40s inland, and the upper 40s
closer to the coast.

.LONG TERM...

The northwest flow pattern will continue to dominate through the
weekend, and a reinforcing frontal passage should occur late
Saturday. This front will be moisture starved, and only expect to
see some passing mid and high level cloudiness accompany the front
and associated upper level vorticity maxima. Temperatures should
warm close to seasonal norms near 70 degrees in advance of the
front Saturday afternoon, but another round of cold air advection
Saturday night and Sunday will push temperatures back to around 5
degrees below average for the rest of the weekend.

Early next week, the northwest flow pattern will finally breakdown
as a strong deep layer ridge builds in from the west. This ridge
axis will remain in control of the area through Tuesday resulting
in continued clear skies and low humidity values. A 925mb cold
pool will linger into Monday, and expect temperatures to remain
around 5 degrees below average in the middle 60s Monday afternoon.
Lows should range from the upper 30s to the mid 40s Monday
morning. This cold pool should shift to the east of the area
Monday night and Tuesday, and expect to see temperatures climb
back to more normal readings in the 40s and low 50s at night and
lower 70s during the day.

Some disagreement in the models develops by next Wednesday, but
both the GFS and the ECMWF indicate that another shortwave trough
will approach from the west as the deep layer ridge axis shifts
toward the eastern seaboard. Winds should turn more southerly
Tuesday and Tuesday night, and this will allow for some moisture
to advect in from the Gulf of Mexico. As a result, expect to see
an increase in cloud cover through the day on Wednesday, and some
scattered showers may try to form in advance of the approaching
trough and associated cold front by Wednesday afternoon.
Temperatures should cool slightly due to the increase in cloud
cover, but readings should only be a few degrees below average on
Wednesday.

&&

.AVIATION...

VFR conditions to prevail. Gusty winds and some minor LLWS
considerations with surge of colder air currently advancing
southward through the area today. Winds should abate Thursday mid-
morning. 24/RR

&&

.MARINE...

Surface cold high pressure will continue to build into the north
gulf tonight then moderating in place through the weekend, allowing
for winds and seas to abate substantially after the advection
neutralizes Thursday morning. Yet another surge of high pressure re-
enforces offshore flow regime Sunday with another cold front poised
to move off the coast next Tuesday night. 24/RR

&&

.DECISION SUPPORT...

DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.

Decision Support Services (DSS) Code Legend
Green  = No weather impacts that require action.
Blue   = Long-fused watch, warning, or advisory in effect or
         high visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
         advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby tropical
         events; HazMat or other large episodes.
Red    = Full engagement for Moderate risk of severe and/or
         direct tropical threats; Events of National Significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  33  60  33  66 /   0   0   0   0
BTR  35  61  35  66 /   0   0   0   0
ASD  35  63  34  67 /   0   0   0   0
MSY  44  62  43  66 /   0   0   0   0
GPT  39  63  39  66 /   0   0   0   0
PQL  38  64  37  68 /   0   0   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 4 AM CST Thursday for GMZ530-532-534-
     536-538-550-552-555-557-570-572-575-577.

MS...None.
GM...Small Craft Advisory until 4 AM CST Thursday for GMZ532-534-536-
     538-550-552-555-557-570-572-575-577.

&&

$$

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