170
FXUS64 KLIX 160456
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1156 PM CDT Wed May 15 2024

...New AVIATION...

.SHORT TERM...
(This evening through Friday night)
Issued at 354 PM CDT Wed May 15 2024

KEY MESSAGES:
1. At least 2-3 waves of showers and storms will be possible from
Thursday night through Saturday morning across portions of Southeast
LA and southern MS. 2 to 4 inches of rain with locally higher
amounts up to 6 inches will be possible mainly north of the I-10/12
corridor. This has prompted the issuance of a Flood Watch for this
period for the threat of localized flash flooding.

2. Thursday night into Friday morning and again Friday night appear
to provide the highest risk for severe weather impacts to our area,
but exact details regarding the magnitude of the threat at this
stage is uncertain. Damaging winds, hail, and a few tornadoes cannot
be ruled.

Fair skies and highs in the 80s today with surface high pressure and
amplifying shortwave ridge overhead. Light winds and clear skies
tonight will allow for another steep low-level inversion from
radiational cooling that will allow moisture trapping and some
shallow, patchy fog in lower-lying areas at daybreak, but no dense
fog concerns are anticipated. As high pressure moves off to the east
and surface pressures begin to fall over the plains, winds will
become southeasterly again and gradually increase. This return flow
and increasing cloud cover during the day on Thursday will be
indicative of what`s coming from upstream.

A deepening, elongated trough ejecting out of the southern Rockies
will feature smaller shortwaves in the leading and trailing flanks
of the larger feature which will result in several rounds of more
favorable forcing for deep convection across the southern Plains and
northern Gulf Coast Thursday through Saturday. The first wave of
deep convection to effect our area appears to be on Thursday evening
through Friday morning associated with a leading shortwave within
the westerly, subtropical jet flow. The threat for severe weather
and excessive rainfall with this feature appears to be focused
mainly along and north of the I-10/12 corridor. Further refinement
will be needed to timing and estimation of magnitude of impacts with
this first wave as newer guidance gets within range tonight and
tomorrow, but the gist highlights an environment supportive of a
strongly forced area of organized convection especially capable of
producing damaging winds and a few tornadoes.

Depending on the progression of this first wave and how it modulates
the thermodynamic environment in its wake, the PoP forecast for the
day on Friday could vary drastically. If the cold pool from this
deep convection surges out and stabilizes the forecast area, new
convection will struggle to develop into the afternoon. If the area
is able to recover faster, or the first wave of storms is not as
robust, more coverage of showers and storms developing over the area
in the afternoon will be possible.

As the main axis of the trough lift into the ArkLaTex region, the
trailing shortwave will assist in kicking off another round of deep
convection that will initiate in coastal/southeast Texas and
propagate east, similar to Monday`s system. Exact details regarding
the impacts with this round of storms is more uncertain given the
situation outlined above. However, it is safe to message that
additional rainfall on top of an already saturated area from the
first round of rain and recent rains will make areas along and north
of the I-10/12 corridor more susceptible to flash flooding.

A linger concern beyond just these rounds of strong to severe storms
will be the prospect of west to east boundary orientation in
relation to the WSW mid-upper flow continuing to promote
redevelopment of showers and storms into the overnight hours Friday
into Saturday morning which could exacerbate flooding concerns
especially in poor drainage and urban areas.

&&

.LONG TERM...
(Saturday through Tuesday night)
Issued at 354 PM CDT Wed May 15 2024

Lingering showers and storms should gradually abate as the trough
lifts out of the area and rising heights suppress convection. The
long term period starting Sunday is a rinse/repeat summer-like
regime where mid-upper ridging building in from the southwest and
dominates much of the Gulf of Mexico leaving us with above normal
temperatures and drier conditions through midweek next week.
Temperatures will be pushing the low to mid 90s at most locations.

&&

.AVIATION...
(06Z TAFS)
Issued at 1150 PM CDT Wed May 15 2024

Generally VFR conditions for the first 18 hours of the forecast
package, with the exception of KMCB and perhaps KHUM, where MVFR
visibilities are possible around sunrise. Cannot entirely rule out
lower visibilities at KMCB, but they didn`t occur this morning
with light and variable winds. Thicker cirrus should arrive during
the late morning or early afternoon hours on Thursday. These
clouds will gradually lower during the afternoon and evening. MVFR
ceilings will move into the area during the evening, with the
potential for SHRA/TSRA at the western terminals prior to 06z
Friday, and moving through all remaining terminals prior to 12z
Friday. Direct impacts will include IFR or lower conditions.

&&

.MARINE...
Issued at 354 PM CDT Wed May 15 2024

Weak northerly winds tonight will become southerly once again by
Thursday night and gradually increase into Friday ahead of the next
low pressure system. Winds of 15-20 knots with some gusts up to 25
knots will be prevailing on Friday, but forecast is not accounting
for impacts from convection. Thunderstorm activity becomes
increasingly likely to cause issues Thursday night through
Saturday morning mainly for the inland and nearshore waters and
headlines for hazardous seas could be raised during this period.
Winds become offshore with boundary passage Saturday night into
Sunday. Thereafter, high pressure gradually builds back in by
Sunday night and drier, calmer conditions prevail into next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  61  87  65  82 /   0  10  70  80
BTR  66  92  71  88 /   0  20  60  70
ASD  66  89  72  88 /   0  10  40  60
MSY  70  89  75  89 /   0  10  40  50
GPT  67  87  73  86 /   0   0  40  60
PQL  64  89  70  87 /   0   0  40  60

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Flood Watch from Thursday evening through Saturday morning for
     LAZ034>037-039-046>048-071-081-083.

GM...None.
MS...Flood Watch from Thursday evening through Saturday morning for
     MSZ068>071.

GM...None.
&&

$$

SHORT TERM...TJS
LONG TERM....TJS
AVIATION...RW
MARINE...TJS