423
FXUS64 KLIX 062041
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
341 PM CDT Mon May 6 2024

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

.SHORT TERM...
(This evening through Wednesday night)
Issued at 243 PM CDT Mon May 6 2024

The region will continue to feel the influence of a shortwave
ridge axis extending in a southwest to northeast orientation
across the Gulf South through the middle of the week. Ample
subsidence in the mid and upper levels beneath this ridge will
continue to produce a strong mid- level capping inversion, and
this will effectively limit any convective potential tomorrow and
Wednesday. At most, an isolated shower may develop over portions
of Southern Mississippi, but deep convection and thunderstorm
activity will be hard pressed to occur tomorrow. By Wednesday, the
strength of the ridging aloft will be so substantial that no
convective activity is expected. Skies will start off mostly
cloudy to overcast as another inversion forms around daybreak both
tomorrow morning and Wednesday morning, but warming temperatures
into the upper 80s and lower 90s will lead to skies turning partly
cloudy by the late morning hours. Overall, a warm and benign
period of weather is expected through Wednesday night.

&&

.LONG TERM...
(Thursday through Sunday night)
Issued at 243 PM CDT Mon May 6 2024

There is little spread in the ensemble members concerning the
passage of a cold front Thursday night into Friday, but there
continues to disagreement and larger spread in the solutions
heading into the weekend. Given the large disagreement in the
forecast solutions over the weekend, have largely stuck with the
NBM deterministic output for the time being.

Initially, a deepening northern stream trough axis will start to
dig into the eastern third of the CONUS. As this trough digs
southward, a southern stream vorticity max will slide out of
Texas and across the Gulf South. This southern stream energy will
tap into a highly unstable airmass as noted by MLCAPE values
Thursday afternoon and evening of 2500 to 3000 J/KG across the
CWA. These high MLCAPE values are being driven by extremely steep
mid-level lapse rates approaching 7.0 C/km. This instability will
tap into a very moist airmass with PWATS expected to climb to to
between 1.75 and 2 inches by Thursday evening. Another factor to
watch for will be just how much speed shear develops in response
to the passage of an 100 knot jet streak co-located with the vort
max. Effective layer speed shear values of 50 to 60 knots could
occur just as the convection begins to develop, and this will
support tilted updrafts and the prospect of scattered strong to
severe thunderstorms Thursday afternoon into Thursday evening.
Based on the model sounding profiles, large hail and damaging wind
gusts will be the primary severe weather concern. Later in the
night, generally after midnight Thursday night, the jet streak
will pass to the east and a surface front will begin to push
across the area. Overall shear values will decrease substantially
and the threat of severe convection should diminish. In addition
to the thunderstorm risk Thursday afternoon into Thursday evening,
compressional heating in advance of the front should allow highs
to warm into the low to mid 90s across much of the forecast area.
Only coastal regions should remain in the upper 80s due to the
influence of the seabreeze cycle.

The area will be post-frontal by Friday morning as a prevailing
west-northwest flow regime develops in the mid and upper levels
and a northerly wind takes hold in the low levels. A cooler and
drier airmass will move into the area with rain chances coming to
an end over the eastern third of the CWA by late Friday morning.
Temperatures will be closer to average on Friday with highs
warming into the low to mid 80s. The warmest temperatures will be
along the Mississippi coast where a weak downslope component will
induce some mild subsidence and warming. The strength of the
northerly wind will be sufficient to suppress seabreeze
development, thus allowing the temperatures to warm on the coast

Saturday and Sunday will see the flow pattern aloft turn more
zonal, and a series of weak and fast moving vorticity maxima
should slide across the northern Gulf of Mexico over this period.
Unfortunately, there are significant differences in the timing of
these systems between the ensemble members of the GFS and ECMWF,
and thus forecast confidence over the weekend is lower. Given the
uncertainty, have opted to stick with NBM forecast values. This
solution results in largely coastal PoP values of 20 to 30 percent
and drier conditions further inland. Temperatures will be largely
near average with highs in the lower 80s and lows in the upper
50s and lower 60s.

&&

.AVIATION...
(18Z TAFS)
Issued at 243 PM CDT Mon May 6 2024

VFR conditions will be found at all of the terminals through the
evening hours. There may be an isolated shower that develops near
MCB this afternoon, but the risk to low to include in the
forecast. Tomorrow morning, generally between 08z and 14z, some
boundary layer decoupling will occur as temperatures cool and
winds decrease. Another round of IFR and MVFR stratus development
is expected with the most prevalent IFR conditions expected at MCB
where decoupling will be greatest. The remainder of the terminals
should see ceilings of 1000 to 1500 feet in the early morning
hours. After 15z, increased thermal mixing of the boundary layer
will allow the stratus deck to begin breaking and lifting into VFR
range.

&&

.MARINE...
Issued at 243 PM CDT Mon May 6 2024

A persistent south to southeast flow of 10 to 15 knots and seas of
1 to 3 feet will continue across the coastal waters through
Wednesday as the region remains on the southwest periphery of a
broad surface high pressure system. However, the approach of a
cold front Wednesday night into Thursday will lead to a slightly
tighter pressure gradient over the waters, and subsequently a
period of stronger onshore flow between 15 and 20 knots. Seas will
increase to 3 to 5 feet in response to these higher winds. After
the front moves through the waters Thursday night, winds will
shift to the north at 10 to 15 knots on Friday and Saturday.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  69  87  71  90 /  20  20   0  10
BTR  73  88  74  91 /  10  10   0   0
ASD  72  88  73  89 /  10  10   0   0
MSY  75  87  75  88 /  10  10   0   0
GPT  74  84  75  85 /  10  10   0   0
PQL  73  84  74  86 /  10  10   0   0

&&

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

$$

SHORT TERM...PG
LONG TERM....PG
AVIATION...PG
MARINE...PG