487
FXUS64 KLIX 261142
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
642 AM CDT Wed Jun 26 2024

...New AVIATION...

.SHORT TERM...
(Today through Thursday)
Issued at 339 AM CDT Wed Jun 26 2024

Upper ridging centered over the Four Corners area early this
morning. Shortwaves, or at least MCV`s, were noted near Kansas
City and over southeast Oklahoma. A few isolated showers over
Plaquemines Parish and over the Gulf, but no indications of
lightning at this point. Early morning temperatures ranged from
the mid 70s to lower 80s across the area with dew points primarily
in the mid and upper 70s. Fairly wet sounding in place with
precipitable water values on the 00z LIX and JAN soundings in the
1.9 to 2.0 inch range, which is generally above the 75th
percentile for late June.

Issues for the first 36 hours of the forecast are twofold, the
threat of thunderstorms and heat stress conditions. While
shortwave energy is approaching from the northwest, it`s rather
questionable at this point whether organized convection develops
prior to mid to late afternoon. Most of the convection allowing
mesoscale models don`t develop much in the way of thunderstorms
prior to 21z this afternoon, with actually the better chance of
organized convection overnight tonight. Unfortunately, there`s
little agreement as to the area to be impacted, with solutions
ranging from Alabama to east Texas. Considering that we can see
separate impulses upstream this morning, can`t entirely rule out
clusters east and west of the area, and little over the local
area. Of course, we also have the issue of southeastward
propagating cold pools generally arriving quicker than the
mesoscale models depict.

The forecast scenario we`ll predicate this morning`s forecast on
is for only isolated to widely scattered areal coverage of
thunderstorms during the midday to late afternoon hours today.
Organized convection will be possible overnight with shortwave
energy moving into the area, and we can`t rule out a strong to
severe storm cluster depending on if a cold pool develops and
where it moves. Redevelopment of showers and/or storms on remnant
outflows is anticipated tomorrow afternoon, but am a bit concerned
that current probabilities of precipitation for Thursday are
somewhat overdone. However, considering decent agreement with
neighboring offices, won`t make changes for now.

With any organized convection not expected prior to early
afternoon, that should allow sufficient time for temperatures to
get into the lower and middle 90s. Combined with dew points in the
mid and upper 70s, that will produce heat indices in the 105 to
110F range for a good segment of the area, at least briefly. It`s
a borderline advisory situation, and have collaborated a Heat
Advisory for the same areas as yesterday for the late morning and
afternoon hours today. If organized convection develops earlier
than expected, the advisory may be cancelled prior to expiration.
Between lingering cloud cover from overnight convection and the
potential for redevelopment tomorrow afternoon, high temperatures
are expected to be several degrees cooler for much of the area,
and do not anticipate a need for advisories tomorrow.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 339 AM CDT Wed Jun 26 2024

For at least Friday through the weekend, the Four Corners upper
ridge is expected to shift eastward and elongate east/west
somewhere near Interstate 20 to our north. Exactly where that
ridge sets up could be the difference between scattered storms
each day, or a dry and hot weekend. Forecast 500 mb temperatures
Friday are expected to be in the -2C to -4C range from north to
south with 700 mb temperatures near or above +10C, and only a
degree or two colder Saturday/Sunday. Usually, those mid level
temperatures Friday are sufficient to shut down convective
development, but most all guidance is showing at least some storm
development.

Wouldn`t be surprised at all to see later guidance back down rain
chances for the weekend and into early next week, which would
probably put us in Heat Advisory range again. NBM deterministic
highs track with the warmer of the global model guidance from
Friday onward, but overnight lows look to be a degree or two too
cool.

&&

.AVIATION...
(12Z TAFS)
Issued at 633 AM CDT Wed Jun 26 2024

Forecast terminals were all VFR at forecast issuance time,
although there are some clouds around the area near FL025. Not
enough to carry widespread ceilings at this point. Most TSRA this
morning are remaining offshore, and if it is a usual morning,
those storms will die out around 15z. Isolated to scattered
SHRA/TSRA may develop by early afternoon, especially along
lake/sea breeze boundaries, but not confident enough to carry any
more than VCTS. Dissipation should come with loss of heating by
sunset. A second potential for TSRA will come after 05z with a
shortwave approaching from the northwest. Again confidence in
timing and particular locations is relatively low, and amendments
as convective development areas become apparent are likely. Any
terminal experiencing direct impacts with either threat will see
IFR or lower visibilities and wind gusts in excess of 30 knots.

&&

.MARINE...
Issued at 339 AM CDT Wed Jun 26 2024

On the large scale, weak pressure gradients should lead to light
wind fields for much of the period, with the exception of the
usual diurnal increase over the sounds and waters east of the MS
delta each evening. Thunderstorms will be more of a concern,
especially during the overnight and morning hours. Considering the
very moist airmass and light low level winds, there will be
potential for slow moving or nearly stationary waterspouts at
times.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  92  73  89  73 /  50  60  80  20
BTR  96  78  93  77 /  50  40  80  20
ASD  94  76  91  76 /  50  40  90  40
MSY  94  78  91  78 /  50  40  90  30
GPT  94  75  91  76 /  40  50  80  50
PQL  96  76  93  75 /  40  50  70  50

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory from 11 AM this morning to 7 PM CDT this evening
     for LAZ034>037-039-046>048-056>060-064-065-071-076>090.

GM...None.
MS...Heat Advisory from 11 AM this morning to 7 PM CDT this evening
     for MSZ068>071-077-083>088.

GM...None.
&&

$$

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