-- Discussion containing changed information from previous version are highlighted. --
484
FXUS64 KLIX 120904
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
404 AM CDT Wed Jun 12 2024

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

.SHORT TERM...
-- Changed Discussion --
(Today through Saturday)
Issued at 400 AM CDT Wed Jun 12 2024

Overall the forecast as a whole is a tale of two scenarios. First
part, high confidence, mostly dry, and HOT. Second part of the
forecast, highly uncertain, increasing rain chances and possibly
very wet, and thus cooler than the first part of the forecast.
Because of that the short term will actually cover through the
first half of the weekend and then we will delve into the abyss
known as the Long Term portion.

Stalled boundary is still apparent in the sfc field and is draped
right along almost the entirety of the northern Gulf coast. High
pressure dominates pretty much all of the eastern CONUS. The other
sfc feature is the weak trough over the eastern Gulf associated with
the heavy rainfall that plagued the srn half of the FL peninsula.
This area has been highlighted by NHC as having a low probability of
developing into a tropical system but it will have zero impacts on
our area as it will move across FL and enter the Atlantic.

Aloft we are still seeing the slight impacts of the weak disturbance
moving across the Lower MS Valley with a L/W trough just off the
east coast. The main drivers of the weather for the short term (well
actually probably most of the forecast) is the strengthening ridge
currently centered over the Mexican states of Sonora and Chihuahua
along the AZ and NM. The ridge axis stretches north across the 4
corners. The other main feature is the closed low that is in the
Pacific west of the Baja and how it evolves as it lifts to the
northeast.

So those are the players for the next week and the main one to watch
is how the ridge evolves. It is specifically the feature we will
focus on in the short term as it builds to the east across the
southern Plains, the Lower MS Valley and into the southeastern CONUS
by Saturday afternoon, likely centered over the TN/MS/AL/GA border.
With that track along with hghts of around 592dm this should provide
more than enough subsidence to keep convection over much of the land
at bay. This will also occur with an increase in LL temps with h925
temps rising from 23-24C today to 27-29C by Saturday. We got
slightly warmer than expected yesterday and see little reason why we
won`t be as warm today. The one slight hiccup that could occur today
is that disturbance coming across the region today. It will cool off
mid lvl temps about a degree or two and with h8 temps possibly
around -8C there is a very small chance that a few storms could try
to develop today. PWs are sufficient enough up to I-12 but the
deeper richer moisture is still locked in along the coast and if
convection can fire inland it will likely be the same areas that saw
it yesterday. That said we will continue to hold on to 15-20%
between I-12 and just south of I-10 for Isolated storms. This should
not be an issue the next few days as that feature will continue to
push to the southeast into the eastern Gulf and across the
southeastern CONUS (but keep en eye on the base of this feature as
it moves into the southeastern and southern Gulf and could help
determine where the rain goes Sunday and next week).

LL moisture doesn`t really start to recover till Friday and more so
on Saturday and these two days will be ones to watch for possible
heat products. LL temps as mentioned earlier will be on the rise and
by Friday h925 temps of 26-28C should easily yield highs in the mid
to upper 90s and can not rule out isolated 100s Friday. Highs could
be a degree or two hotter on Saturday with probably more than a few
sites testing the century mark. With the ambient temperature getting
that warm, any increase in LL moisture will make for an oppressive
environment and by Friday we should start seeing widespread heat
index values of 100 to the mid 100s. Saturday though we will finally
see light to moderate onshore flow and that will finally see a surge
of LL moisture push in. With the ridge overhead likely keeping
convection out of the area we will heave little problems heating up
and combine that with a very humid airmass and we will see quite the
oppressive airmass and Heat Adv are beginning to look likely for
Saturday and can not rule that out for Friday. /CAB/
-- End Changed Discussion --

&&

.LONG TERM...
-- Changed Discussion --
(Saturday night through Tuesday)
Issued at 400 AM CDT Wed Jun 12 2024

Now the not so clear part of the forecast, Sunday through Tuesday.
Medium range models all suggest at least some rain moving in
Sunday. The increase in cloud cover along with rain helps to cool
things off a tad but how much rain, when does it arrive, and how
long does it stick around is quite uncertain. With so much
uncertainty and rather low confidence we will stick with the NBM
for now but that said personally I am leaning to a drier western
solution and we will get into that.

There appears to be 2 camps, 1 with a better chance of rain over the
3 days, and the other which keeps the bulk of the rain to our west
and southwest. The ensembles aren`t a great deal of help either as
they are kind of washing things out and broad brushing rain across
the western half of the Gulf. A lot of this appears to hinge on the
ridge and how it evolves/moves.

The camp with the better rain chances and even possibility of heavy
rain for the north-central Gulf coast shows the ridge continuing to
push east-southeast across the southeastern CONUS and nudging into
the Atlantic. This causes the western edge of the ridge to slide far
enough east allowing for a path NNW towards the north-central and
northwestern Gulf. This also cuts off the base of the weak trough
over the eastern Gulf that is currently moving through us right now.
That would allow allow the weak mid lvl feature to work NNW and it
along with a deep and rich plume of tropical moisture could bring
about widespread rain to the area by Sunday and possibly through
Tuesday. This would also be capable of producing very heavy rain as
was evident in FL yesterday. If this scenario plays out even trying
to pinpoint where the heaviest rain would  occur is still too
difficult at this time.

Scenario 2 which seems like the operational models were trying to
trend towards would be a drier set up for our area and the bulk of
the rain likely going into TX if not southern TX and Mexico. Why is
that, again it is the ridge that will bring us our hot temps. In
this scenario the ridge doesn`t shift as far east and the Pacific
low we mentioned earlier, as it lifts to the northeast it wouldn`t
eroded the western periphery of the ridge as much and right up over
it. If that occurs the ridge would basically be a blocking setup for
us. The ridge is not extremely large and even centered in that
TN/MS/AL/GA area we would be on the southern Periphery. This would
at the least allow some moisture to move north providing an increase
in cloud cover and some convection Sunday and Sunday night but after
that we probably get shut down. With the s/w riding up and over the
ridge, the ridge is going to want to expand back to the west and
this would keep any disturbance and deep tropical moisture well off
to our west and southwest. Even though we didn`t make any
adjustments away form the NBM this scenario feels like the more
probably solution. Ridges are stubborn and the Pacific low as it
opens up and lifts to the northeast will likely ride up and over it
as there doesn`t appear to be anything blocking it from driving that
direction. This would also allow the western portion of the ridge
axis to quickly push back to the west and basically blocking things
from moving to far to the northwest. This mainly the OP ECMWF
solution and it doesn`t have a ton of support right now as the the
GFS and GEM are both well off to the east and the ensemble means are
in between with the ECS having the greatest dispersion of
solutions. /CAB/
-- End Changed Discussion --

&&

.AVIATION...
(06Z TAFS)
Issued at 1153 PM CDT Tue Jun 11 2024

VFR conditions are expected for most terminals with HUM having
MVFR due to visibility. That should clear up early tomorrow
morning after sunrise. Terminals should then be VFR throughout the
day with a low chance of some showers/storms near the southern
terminals during the afternoon hours. -BL

&&

.MARINE...
-- Changed Discussion --
Issued at 400 AM CDT Wed Jun 12 2024

Boundary is still stalled along the coast and should start to wash
out Thursday night and Friday. Until then light and variable winds
to northernly winds of 5-10 kts will continue. After the front
washes out looks for winds to become more easterly and then by
Friday night and more so this weekend onshore flow will develop
and could become moderate times. A decent fetch out of the
southeast may develop this weekend and into next week and that
could bring an increase in the potential for swells. Convection is
still possible over the coastal waters through the week but much
highs rain chances will be in place Sunday and into next week and
with any convection locally higher winds and seas are to be
expected. /CAB/
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
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MCB  90  63  92  67 /  10   0   0   0
BTR  94  69  96  72 /  10  10  10   0
ASD  94  70  95  72 /  10  10  10   0
MSY  94  77  94  77 /  20  10  10   0
GPT  93  71  94  75 /  10  10  10  10
PQL  95  69  97  73 /  10  10  10  10
-- End Changed Discussion --

&&

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

$$

SHORT TERM...CAB
LONG TERM....CAB
AVIATION...BL
MARINE...CAB