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

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FXUS64 KLIX 231039

Area Forecast Discussion
National Weather Service New Orleans LA
439 AM CST Thu Feb 23 2017

.SHORT TERM (Today through Saturday night)...

A ridge of high pressure both at the surface and aloft will result
in dry conditions today. The surface high will be moving east of
the forecast area today which will result in a return flow of
southerly winds by afternoon, and it will be warmer in most
locations with unseasonably warm highs mostly in the upper 70s to
lower 80s, a bit cooler close to the coast.

A broad mid/upper level trough over about the western half of the
continental U.S. will have a shortwave axis moving east into the
plains late tonight into Friday, and an associated, rather strong
surface low is expected to move from the central plains to the
western Great Lakes region tonight and Friday. This low will drag
a cold front into the Ark-La-Tex region by early Friday morning,
and this front will continue to push southeast and through the
forecast area Friday night. There will not be much moisture for
this front to work with (precipitable water 1.0 to 1.2 inches),
but there should be isolated showers along the front starting in
southwest Mississippi and east central/south central Louisiana
Friday evening, and areas south of Lake Pontchartrain and in
coastal areas after midnight.

Drier and cooler air will precede the cold front Saturday into
Saturday night as surface high pressure builds over the forecast

.LONG TERM (Sunday through Wednesday night)...

A broad mid/upper level trough will once again set up over the
western states Tuesday (Mardi Gras) as a series of shortwaves
move through the fast flow in both the northern and southern
streams during the early to middle of the week. The 00z GFS/ECMWF
operational runs today indicate a fast moving shortwave trough and
associated weak surface low will move east across the southern
plains and lower to mid Mississippi valley Sunday night into
Monday morning while dampening out. Southern stream energy/forcing
and possibly a weak surface boundary (more a trough, not a front)
will likely interact with sufficient moisture and instability to
produce scattered showers and isolated thunderstorms across the
forecast area Monday (Lundi Gras), with some isolated showers
north and west starting Sunday night. Have raised the PoP on
Monday from the previous forecast. Some showers and storms could
linger Monday night mainly north of the I-10 corridor. Mardi Gras
Tuesday into Tuesday night is a tough call at this point with a
broad belt of west-southwest winds aloft due to continued
troughing over the western states to Baja region. The GFS shows
some showers/possible thunderstorms lingering while the ECMWF is
mostly dry. Have continued with a slight chance of showers and
some thunderstorms. The models are in somewhat better agreement
that Wednesday will see higher rain chances, so have maintained
rain chances in the 30 to 50 percent range. Regarding temperatures,
it is expected to be rather warm early in the week, with Mardi
Gras Tuesday likely the warmest with upper 70s to lower 80s for
highs. 22/TD



Patchy fog this morning could reduce visibilities to between 1 and 3
miles at times between now and 14z.  After 14z, VFR conditions will
be the rule through at least 00z as drier air aloft mixes down to
the surface. The environment for fog and low ceiling development
looks even more favorable from around 06z tomorrow through 12z.  A
mix of IFR and LIFR visibility and ceiling restrictions could impact
all of the terminals at times between 06z and 12z tomorrow. 32



A brief period of rather benign conditions will exist over the
coastal waters through tomorrow with winds generally ranging around
10 knots or less.  Seas will also be manageable at 2 to 4 feet in
the open Gulf waters and 1 to 3 feet in the lakes and sounds.  A
strong cold front is expected to sweep through the coastal waters
late Friday night and early Saturday morning.  A surge of colder and
drier air over the warmer waters will allow strong boundary layer
winds in excess of 20 knots to mix down to the surface resulting in
a period of Small Craft Advisory conditions.  By Saturday night,
winds should ease back to 15 to 20 knots over the open Gulf waters
and remain at this level through next Tuesday.  over the lakes and
sounds, winds should ease to 10 to 15 knots Saturday night and
remain at these levels through Tuesday.  The wind direction will
veer from north and northeasterly on Saturday and Sunday to a
southeast and southerly direction by Monday and Tuesday.  Seas will
remain rough due to these winds with seas of 4 to 6 feet expected
over the open Gulf waters from Saturday through Tuesday.  Waves of 3
to 5 feet can be expected in the lakes and sounds.  32



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.


MCB  80  56  81  48 /   0   0   0  20
BTR  80  57  82  50 /   0   0   0  20
ASD  77  55  77  53 /   0   0   0  20
MSY  78  59  80  55 /   0   0   0  20
GPT  74  57  76  54 /   0   0   0  20
PQL  77  55  77  54 /   0   0   0  20



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