633
FXUS64 KLIX 281144
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
644 AM CDT Fri Jun 28 2024

...New AVIATION...

.SHORT TERM...
(Today through Saturday)
Issued at 400 AM CDT Fri Jun 28 2024

Upper ridging building eastward early this morning, but is
elongated northeast to southwest from Baja California to Texas to
Arkansas, instead of the east-west formation that has been
forecasted. Additionally, at least for now, it doesn`t appear to
be as strong as forecast, with 500 mb heights around 5900m. A
shear axis or weak trough extended from the Carolinas to near
Mobile to the western Gulf of Mexico. Scattered thunderstorms have
been firing along this axis, producing locally heavy rainfall,
primarily south of Interstate 10. Early morning temperatures
ranged from the mid 70s to lower 80s with dew points primarily in
the mid and upper 70s.

Not to sound repetitive or anything, but the short term forecast
issues are thunderstorm chances and heat related issues.

There isn`t going to be a lot of movement of the shear axis over
the next 36 hours. The ridge just to the northwest is forecast to
strengthen a bit while the shear axis weakens. Precipitable water
values had dropped off to around 1.7 inches or so Thursday
afternoon, are forecast to recover to 1.9 to 2.0 today and 2.0 to
2.25 on Saturday. With convective temperatures forecast in the
lower 90s, it will probably take until early afternoon for
convection to initiate once the current activity dissipates.
Storms should weaken over land during the early evening, before we
start seeing storms in the marine areas overnight. On Saturday,
convective temperatures aren`t much different, perhaps 1-2 degrees
warmer, so once again, most of the storms should occur in the
afternoon hours over land. While instantaneous coverage of storms
either day probably won`t get a great deal above 30-40 percent,
over the daylight hours as a whole, probably 60 to 70 percent of
people will see measurable rain at some point, with the exception
of the far northwest portion of the area under the building ridge.
That being said, have undercut the NBM PoPs a bit.

With somewhat better afternoon areal coverage of storms today, we
may fall just short of yesterday`s high temperatures, although
lower to middle 90s appears to be a good bet. Forecast heat
indices are expected to remain below Heat Advisory criteria (108F)
today. With the upper ridge strengthening and shear axis weakening
tomorrow, that should allow high temperatures a degree or two
warmer. Forecast guidance also indicates dew points 1-2F higher on
Saturday. A Heat Advisory issuance appears to be more probable
for Saturday.

&&

.LONG TERM...
(Saturday night through Thursday)
Issued at 400 AM CDT Fri Jun 28 2024

Upper ridging does eventually force the shear axis out of the
area by Sunday as it consolidates just to the west of the area
near the Texas-Oklahoma border. It then builds east and eventually
stretches along the Interstate 20 corridor for the middle and end
of next week. Moisture levels remain rather high, with
precipitable water values remaining near or above 2 inches and
surface dew points generally in the mid and upper 70s. That will
generally mean daily thunderstorm development during the diurnally
favored cycle of during the afternoon over land, and late night
over marine areas. With daytime high temperatures continuing to be
in the mid 90s in much of the area, Heat Advisories will probably
be necessary Sunday and for several days beyond, at least. Didn`t
make many adjustments to NBM deterministic temperature forecasts
other than to bump up overnight lows a degree or so.

&&

.AVIATION...
(12Z TAFS)
Issued at 629 AM CDT Fri Jun 28 2024

Most terminals were VFR at forecast issuance, but MVFR ceilings
are expected in the vicinity of SHRA. Areal coverage is rather
limited, but KASD and KBTR could be impacted in the next couple
hours. IFR or lower visibilities and MVFR ceilings briefly
possible with these SHRA. A bit more widespread MVFR ceilings are
expected as the cumulus field develops around 14-15z.

Isolated to scattered TSRA will be possible beyond 18z at most or
all terminals, with possibly the least threat at KMCB.
Instantaneous areal coverage will probably not get much above 30
percent or so this afternoon. Will generally carry VCTS for now,
with amendments as necessary if it appears direct impacts can be
anticipated. Most TSRA should dissipate near or after sunset.

While most of the overnight hours should see VFR conditions, the
terminals near and south of I-10 (KGPT/KASD/KNEW/KMSY/KHUM) will
have the potential for isolated SHRA after about 08z. It`s
happened the last 3 nights, and with no significant changes in
airmass or upper pattern, expect it`ll happen again Saturday
morning. With the early morning activity, there`s generally been
little or no lightning, but brief gusty winds wouldn`t be out of
the question.

&&

.MARINE...
Issued at 400 AM CDT Fri Jun 28 2024

With high pressure generally over the area, a generally light wind
regime is expected. The main concerns for mariners will continue
to be thunderstorms, especially during the overnight and early
morning hours. Additionally, the very rich low level moisture and
light winds through the column would lead to a potential for
waterspouts during the late night and morning hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  92  74  92  74 /  60  20  60  10
BTR  96  79  96  78 /  60  20  60  10
ASD  93  78  94  77 /  70  40  70  10
MSY  92  80  94  80 /  70  30  70  10
GPT  92  78  92  78 /  60  40  70  20
PQL  94  78  95  77 /  50  50  60  20

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

$$

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