154
FXUS64 KLIX 170845
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
345 AM CDT Mon Jun 17 2024

...New SHORT TERM, LONG TERM, MARINE...

.SHORT TERM...
(Today through Tuesday)
Issued at 338 AM CDT Mon Jun 17 2024

Upper ridging centered over the Carolinas this morning, with a
second ridge over Baja California. A weakness between the two is
combining with the Central American Gyre to pump deep moisture
northward across the local area. An area of low pressure is
expected to develop over the Bay of Campeche over the next couple
of days associated with the Gyre. The impulse that produced
showers and storms across the area on Sunday has moved north of
the area, but the next impulse is already noted on water vapor
imagery over the central Gulf of Mexico moving northward. The 00z
LIX sounding last evening already showed precipitable water values
in excess of 2 inches, which is above the 90th percentile
climatologically.

Already seeing radar returns on LCH radar over their coastal
waters, and expect to start seeing them on the HDC radar over the
next hour or so. Deep moisture is expected to remain in place
today with precipitable water values remaining in the 1.9 to 2.2
range, which will be in the top 10 percent climatologically for
mid June. Expect pretty widespread areal coverage of precipitation
today, which will produce locally heavy downpours (2 inches per
hour possible). Not everyone will see rainfall that heavy, but if
one occurs over an urban or poor drainage area, it will have the
potential to cause localized flash flooding. Over the course of
the day, areal average rainfall of 1 to 2 inches appears likely,
with spot higher totals. However, don`t expect widespread totals
heavy enough to justify a Flood Watch at this time. Similar to
Sunday, expect a significant decrease in areal coverage of
showers/storms toward sunset this evening, through the overnight
hours. Another surge of showers and storms is expected on Tuesday,
with precipitable water values similar to today. However, the
impulse driving that round is expected to be further west, more
toward western Louisiana, where the axis of heavier rainfall is
expected.

The pressure gradient between the expected low pressure over the
Bay of Campeche and high pressure over the Carolinas will bring an
increase in surface winds across coastal areas, especially on
Tuesday. A Wind Advisory may be necessary across coastal areas
near and to the south of Interstate 10 on Tuesday. The persistent
southeast winds expected will cause higher tide levels along east
and south facing shorelines as early as late tonight, and don`t
see a need for adjustments to the Coastal Flood Advisory at this
time.

Regarding temperatures, can`t rule out a few spots touching 90
degrees today or tomorrow, but the high areal coverage of showers
and storms should hold highs in most areas in the 80s. With the
deep moisture remaining in place, overnight lows are going to have
a tough time dropping below the mid 70s tonight.

&&

.LONG TERM...
(Tuesday night through Sunday)
Issued at 338 AM CDT Mon Jun 17 2024

Wednesday and Thursday are expected to be comparatively dry as
upper ridging builds back in from the east briefly. The airmass
only dries out somewhat with precipitable water values falling to
about 1.8 inches and no large scale forcing. We should be back to
more of a summertime convective regime with overnight/early
morning marine convection and isolated to scattered afternoon
precipitation over land. Beyond Thursday, details remain uncertain
regarding an inverted trough to our east. At this point, it
appears that significant precipitation associated with the trough
should remain to the east of the local area for the weekend.

Even with the drier weather Tuesday night/Wednesday, the
southeasterly winds will continue pushing water toward the coast,
with water levels somewhat higher Wednesday than Tuesday. At this
point, it appears that we should stay at advisory levels, but
can`t entirely rule out the need for a Coastal Flood Warning in a
few of the more vulnerable locations. The tidal lakes will
probably need to be added in a later forecast package, as they may
have issues by Wednesday or Wednesday night.

High temperatures Wednesday and Thursday will creep up a bit from
today and tomorrow to around 90, then into the lower and middle
90s over the weekend. Overnight lows will continue to be above
normal.

&&

.AVIATION...
(06Z TAFS)
Issued at 1133 PM CDT Sun Jun 16 2024

Most of the convection has moved out of the region this evening.
This will be a brief break in the rain/storm chances so carried
only VCs overnight for showers. That said, mostly VFR anticipated
overnight. MCB may drop into IFR ranges with CIGs toward sunrise
with also a reduced VIS. Otherwise, convection will again develop
again later this morning and continue to stream south to north. A
bit higher confidence in convection on Monday vs Sunday as well
as timing. Continued VCTS as exact timing of embedded thunder is
currently tough to pin down. Otherwise, southeasterly winds will
begin to increase across the region with many sites gusting over
20kts by mid to late morning through the end of the cycle. (Frye)

&&

.MARINE...
Issued at 338 AM CDT Mon Jun 17 2024

Have noted a few locations seeing sustained winds near or just
above 20 knots this morning. Small Craft Exercise Caution
headlines will be replaced with Small Craft Advisories over most
waters at 12z, although it may take until midday for some waters
to get near 20 knots sustained. Advisory level conditions expected
to continue overnight tonight into at least Tuesday morning. Not
out of the question that we could reach gale levels over portions
of the waters Tuesday or Wednesday, but we will allow oncoming
shift to take another look. The long fetch of these winds will
produce a swell train over the open waters which is likely to push
seas to at least 9 to 12 feet over the open waters by Tuesday
night into Wednesday. Hazardous to dangerous conditions should be
anticipated for much of the work week, especially over the open
waters, with not much improvement expected until perhaps Friday.

As noted above, with the prolonged southeasterly winds, east and
south facing shorelines will see increased water levels beginning
overnight tonight, and a Coastal Flood Advisory will remain in
effect as issued previously, and will likely eventually need
extended into Thursday. Coastal Flood Warnings may be necessary
for more sensitive spots by Tuesday night or Wednesday. Will hold
off on tidal lakes for this run, as it appears their main water
concerns may hold off until Wednesday night or Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  86  72  84  72 /  80  30  40  10
BTR  88  77  87  76 /  90  30  60  10
ASD  87  76  87  76 /  90  40  60  20
MSY  87  80  87  81 /  90  40  80  30
GPT  88  77  88  77 /  80  40  60  30
PQL  90  76  91  76 /  80  40  40  30

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Small Craft Advisory from 7 AM this morning to 7 AM CDT Thursday
     for LAZ068.

     Coastal Flood Advisory from 1 AM Tuesday to 4 PM CDT Wednesday
     for LAZ066>070-076-078.

GM...Small Craft Advisory from 7 AM this morning to 7 AM CDT Thursday
     for GMZ536-538-550-552-555-557-570-572-575-577.

MS...Coastal Flood Advisory from 1 AM Tuesday to 4 PM CDT Wednesday
     for MSZ086>088.

GM...Small Craft Advisory from 7 AM this morning to 7 AM CDT Thursday
     for GMZ538-550-552-555-557-570-572-575-577.

&&

$$

SHORT TERM...RW
LONG TERM....RW
AVIATION...RDF
MARINE...RW