Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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FXUS64 KLIX 130011
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
711 PM CDT Fri Jul 12 2024

...New EVENING UPDATE...

.EVENING UPDATE...
Issued at 654 PM CDT Fri Jul 12 2024

Performed a brief gridded update this evening to reflect recent
radar/obs trends. Only near-term focus were on ongoing PoPs as
scattered (strong) convection has erupted west of I-55. These
have a lot of available energy to work off of right before we
lose supportive sunlight, and are mostly focused and forced along
remnant outflow boundaries that build off of previous collapsing
convection nearby. High freezing levels around 15.5kft and -20C
levels around 27.3kft, plus warm H5 temperatures at -6C should
keep these from becoming too robust, but drier mid-level air has
introduce greater entrainment potential to produce gusty winds
around 40mph with the most intense storm. Otherwise, convection
should dissipate shortly after sunset revealing a quiet night.

After midnight, we`ll have to monitor yet again another morning
potential of a few waterspouts - moreso focused on the landbreeze
boundary draped from central Lake Pontchartrain to the tidal
lakes/sounds south of coastal MS during the time of peak marine
instability from 09-14Z. Very weak boundary layer shear and ample
moisture will support any stationary "rooted" updraft to these
boundaries, where they will propagate against the weak mean flow,
if not become stationary all together. Will target these with
MWS/SMW`s as we identify them so be aware for those traveling that
a few may be possible yet again. These are typically harmless at
a distance but can be hazardous to boaters or to those traveling
over bridges. If boating, steer clear of them and keep a good
distance. If you see one nearing a bridge you are crossing over,
pull over or slow down if possible and let it pass again keeping a
good distance. All of this activity will likely come to an end
around mid- morning. KLG

&&

.SHORT TERM...
(This evening through Saturday night)
Issued at 300 PM CDT Fri Jul 12 2024

Upper ridging was centered over Utah this afternoon, with a weaker
ridge over the eastern Gulf of Mexico. In between, a trough
extended from Lake Huron southwestward to Missouri and then into
west Texas. Areal coverage of showers/thunderstorms has diminished
considerably over the last couple hours, with nothing more than
isolated storms at this writing, and most of that north of
Interstate 10. With the exception of areas that have seen
precipitation in the last hour or two, temperatures were in the
upper 80s and lower 90s at 2 PM CDT.

While upper air soundings at 12z and water vapor imagery indicated
abundant moisture in place this morning, it`s apparent that some
drying has occurred this afternoon. Precipitable water values that
were in the 2.0 to 2.2 inch range this morning are likely closer
to 1.9 in much of the area now, and those values are likely to
remain, or fall a little more to 1.7 or 1.8 inches across much of
the area tomorrow. This should mean less areal coverage of storms
tomorrow. Have undercut NBM PoPs by 10-15 percent for tomorrow,
but GFS/ECMWF MOS numbers near 20 percent would indicate we`re
still overstating the threat. There`s enough support from
Convection Allowing Models to not discount the NBM numbers
entirely. Most of the morning hours should remain dry, with any
significant thunderstorm threat being during the mid to late
afternoon hours.

With less areal coverage of storms expected tomorrow, that`s going
to allow temperatures to heat up several degrees as compared to
today. Highs in the middle 90s for much of the area, combined with
dew points in the mid 70s will produce heat index values in the
107 to 112F range for a significant portion of the area Saturday
afternoon. We`ve issued a Heat Advisory for Saturday afternoon for
the area, with the exception of the lower portions of the
Louisiana coastal parishes.

&&

.LONG TERM...
(Sunday through Thursday night)
Issued at 300 PM CDT Fri Jul 12 2024

As the Utah ridge tries to spread eastward on Sunday, the
troughing to the east of it attempts to suppress the Gulf ridge
southward. Moisture levels on forecast soundings rebound to closer
to 2 inches on Sunday, which will mean a little better chance for
thunderstorms. Current indications are that we will probably still
need a Heat Advisory across most of the area on Sunday, but we`ll
hold off to see if the current expectations on precipitation
continue.

Weak troughing is expected to remain across the Lower Mississippi
River Valley for much of next week. Precipitable water values will
be high enough (1.9-2.0 inches) to not preclude convection during
any afternoon next week. We`ll also be borderline for Heat
Advisories on most days next week, considering that conditions
could reach criteria prior to convective initiation each
afternoon. No significant adjustments made to NBM deterministic
numbers.

&&

.AVIATION...
(00Z TAFS)
Issued at 635 PM CDT Fri Jul 12 2024

Mainly quiet - VFR conditions anticipated this evening to 06Z
other than some lingering TSRA mainly between KHDC and KBTR, but
is expected to dissipate going into 01-03Z. Anticipating another
morning of coastal showers between 10-14Z, and did mention VCSH
for KNEW briefly but will dissipate before more scattered TSRA
develops between 18-00Z SAT. Best period for coverage will be
around mid to late afternoon, bringing periodic reduced VIS/CIGs
dropping flight categories at times, but will remain largely VFR
outside of any TSRA activity. KLG

&&

.MARINE...
Issued at 300 PM CDT Fri Jul 12 2024

Main marine concerns will be convectively related, as general
pressure pattern produces winds generally below 10 knots and seas
2 feet or less. Thunderstorm development generally late night
through mid morning can produce locally gusty winds and higher
seas. Several waterspouts have developed each of the last several
mornings, and anticipate the next few mornings won`t be any
different.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  71  94  74  93 /  20  50  20  60
BTR  76  96  78  96 /  20  50  20  60
ASD  75  95  77  95 /  10  40  20  50
MSY  77  94  79  94 /  10  40  20  60
GPT  76  93  78  94 /  20  40  20  40
PQL  75  96  76  97 /  10  30  20  30

&&

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

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

GM...None.
&&

$$

UPDATE...KLG
SHORT TERM...RW
LONG TERM....RW
AVIATION...KLG
MARINE...RW