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FXUS64 KLIX 240459
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1159 PM CDT Thu Mar 23 2017

.AVIATION...
Pretty decent low level winds to maintain good visibility but a
marine layer deck that may lower to IFR briefly around sunrise
before lifting to MVFR levels. Convection develops to the west of
the terminal locations during the day and start impacting KBTR and
KMCB toward the latter portion of the valid period. The remaining
locations will have organized convective onset in subsequent hours
to be included in the 12Z issuance. 24/RR

&&

.PREV DISCUSSION... /issued 424 PM CDT Thu Mar 23 2017/

SYNOPSIS...
Latest surface analysis showed a stationary front extending from
a deep 996mb low over the central plains to northwest Louisiana
to Florida parishes to Mississippi coastal waters. Surface flow
was generally southeast parallel to the frontal zone. Surface
dewpoint readings were in the mid to upper 50s northeast of the
boundary except Mississippi coast with values in the lower 60s off
the sound. Dewpoint values were in the 60 to 67F southwest of the
boundary.

Upper air analysis showed a ridge axis from northeast Gulf of
Mexico to the Great Lakes Region and developing closed low over
the Four Corners Region. Isotach at 250mb initialized jet max of
130 knots on the base and front side of the wave/low.

SHORT TERM...
Deep surface trough/low over the Central Plains will begin to dive
east southeast through Friday. Strong jet max off the Southern
Rockies will allow the system to entrain dry air. This will
tightened the moisture axis along the disturbance ahead of the
closed low. Surface base cape values will increase across the
west zones Friday afternoon with values 300 to 500 j/kg. However,
the most of the lift will occur Friday night into Saturday. As a
result, will maintain slight chance of convection Friday
afternoon.

Low level southeast to south flow and southwest flow aloft will
increase 0-3km helicity values 250 to 400 m/s Friday evening
through early Saturday mainly across the north half of the
forecast area. Isolated storms that will have a chance to yield a
tornado will likely occur when the initial convection moves east
into northwest zones around midnight Friday night. Cape values do
increase with values of 700 j/kg across southwest Mississippi to
1500 j/kg along the Louisiana. With the upper level disturbance
rotating southeast through the forecast area Friday night a few
storms may contain damaging winds and hail. 500mb temps may dip
to -17F across northwest zones early Saturday behind the
disturbance. As a result, a few storms may contain hail. As for
now, damaging winds and hail storms are the main threat and
isolated tornadoes as a secondary threat due to the small timing
window.

LONG TERM...
With no true frontal passage over the weekend, low level moisture
will remain in play. However, mid layer moisture will be pushed
east provide a break on Sunday. A short wave will rake across the
north zones on Monday yielding a few storms, and few of these
storms could be strong but below severe limits.

Meanwhile in the latter part of the forecast, a very strong
system will approach the Lower Mississippi Valley late Wednesday
into Thursday. While 7 to 8 days away, the pattern does support a
round of strong to severe across the forecast area late next week.

AVIATION...
VFR conditions will continue at all of the terminals through 00z.
However, an area of MVFR ceilings around 2000 feet will begin to
advect into the area between 00z and 06z. KGPT will see ceilings
develop closer to 00z while KBTR should see ceilings develop
closer to 03z. These ceilings should then persist through the
remainder of the forecast period. Southerly winds will also
increase by 12z tomorrow with sustained winds of 15 to 20 knots
and gusts over 25 knots possible. 32

MARINE...

Surface low will continue to deepen over the Central Plains and
tightened the pressure gradient. Will maintain Small Craft
Exercise Caution headlines for this evening. Winds are expected to
increase to 20 knots over extreme eastern waters after midnight.
The remainder of opening waters will see wind speeds increase to
20 to 25 knots on Friday. Will issue a Small Craft advisory to
cover this hazard. Mariners should also be aware of the potential
for one or more lines of thunderstorms to move through the waters
late Friday night into Saturday. Likely to be a prolonged period
of southeast or south winds over the waters through at least
midweek next week, outside of thunderstorms. 18

DECISION SUPPORT...
DSS CODE...BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...NONE.


DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
WATCH/WARNING/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 TONIGHT RISK SVR
AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
SIGNIFICANCE

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB 63 77 65 75 / 10 20 70 70
BTR 64 80 67 78 / 10 20 70 60
ASD 66 77 67 78 / 10 20 20 70
MSY 66 79 68 78 / 10 20 20 70
GPT 67 75 66 73 / 10 20 10 70
PQL 64 74 64 74 / 10 20 10 70

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 7 PM CDT Friday for GMZ557-575-577.

Small Craft Advisory from 7 AM to 7 PM CDT Friday for GMZ536-570-
572.

MS...None.
GM...Small Craft Advisory until 7 PM CDT Friday for GMZ575-577.

Small Craft Advisory from 7 AM to 7 PM CDT Friday for GMZ570-572.

&&

$$
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