286
FXUS64 KLIX 130916
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
416 AM CDT Thu Jun 13 2024

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

.SHORT TERM...
(Today through Saturday Night)
Issued at 300 AM CDT Thu Jun 13 2024

Today will see increasing negative vorticity advection throughout
the day as a ridge begins to expand eastward from the southern
Plains and Texas. However, there should be enough residual
moisture below 700mb to support the development of isolated to
widely scattered convection along and south of I-10 with the
greatest probabilities along the coast of Louisiana and offshore
later this afternoon. PWATS from New Orleans southward will range
between 1.75 and 2 inches due to this residual moisture, and lapse
rates along the coast will support deeper convection that could
produce some brief heavy downpours and locally gusty winds. Given
this threat, have PoP values of 20 to 40 percent in place for
locations south of I-10. To the north of I-10, the influence of
the building ridge will induce enough subsidence to effectively
cap off convective development. At most, some fair weather cumulus
development can be expected this afternoon. Temperatures will be
seasonably warm with highs in the upper 80s and lower 90s.

Any convection will quickly dissipate early this evening with the
loss of daytime heating and skies will clear. Late in the night,
increasing low level instability over the warmer Gulf waters will
support scattered shower and thunderstorm development during the
diurnal minimum around daybreak. A few of these showers and storms
may move toward the immediate coast and this reflected by 20
percent PoP. Overnight lows will be near average.

The shower and thunderstorm activity will be even more suppressed
on Friday and Saturday as deep layer ridging becomes centered over
the region. Very dry air aloft associated with deep layer
subsidence will effectively cap off any rain chances over most of
the forecast area both days. This drier airmass will result in
precipitable water values dropping to around an inch over
northern zones and closer to 1.4 inches along the coast. These
values are in the 10th to 25th percentile for mid-June. The only
region that may see an isolated shower or thunderstorm develop
will be along the immediate coast where low level convergence is
enhanced along the sea-breeze. Otherwise, only fair weather
cumulus development is anticipated each afternoon. Temperatures
will also be warmer than average with readings in the mid to upper
90s expected. Fortunately, the drier air mixing down to to the
surface will keep dewpoints just low enough to produce heat index
values of 100 to 105. These values are below our advisory
criteria, but those who are more susceptible to heat illness
including the elderly should limit time outdoors on Friday and
Saturday.

&&

.LONG TERM...
(Sunday through Wednesday)
Issued at 300 AM CDT Thu Jun 13 2024

The deep layer ridge axis will shift to the east of the area on
Sunday, and this will open the door for a plume of deeper tropical
moisture to begin feeding into the region. Sunday will see PWATS
rise back to average for mid-June, and this will allow for greater
convective activity by Sunday afternoon. PoP values will range
from 30 to 50 percent north of I-10 and 50 to 70 percent south of
I-10. The highest rain chances will be along the immediate coast
and offshore where the deepest moisture is expected. The influence
of the departing ridge will still be felt, especially over
northern zones, as drier air in the mid- levels lingers. This
drier air aloft when combined with fairly steep low level lapse
rates could lead to a few wet microburst events Sunday afternoon
as convective updrafts punch above 20k feet. Fortunately, the
storm motion will be around 10 knots, and this will help to limit
the heavy rainfall threat over portions of the southshore on
Sunday. The impact of the increased cloud cover and convective
activity will keep temperatures closer to seasonal averages in
the upper 80s and lower 90s.

The convection will be less pronounced Sunday night with the loss
of daytime heating, but a weak upper level impulse rounding the
southwest periphery of the upper level high over the Southeast
CONUS will keep isolated to scattered convective activity in place
over inland zones through the overnight hours. More numerous
showers and storms are expected over the warmer offshore waters as
the diurnal minimum is reached toward daybreak and low level
instability increases. An increase in dewpoints into the 70s will
keep overnight lows a few degrees above average with readings only
dipping into the lower 70s over southern Mississippi and the
upper 70s south of I-10.

Monday through Wednesday looks to be a much more unsettled stretch
of weather as the region remains on the western periphery of a
deep layer ridge and deep tropical moisture continues to feed into
the region. PWATS will be in the 90th percentile or higher each
day with readings of between 2 and 2.25 inches expected. The
result will be numerous showers and thunderstorms forming each day
as temperatures climb into the mid to upper 80s. This reflected by
the high PoP values of 60 to 80 percent forecast each day. The
convective activity will decrease in coverage a bit each night as
temperatures cool back into the 70s, but will still be at least
scattered in nature. Storm motion will remain decent at 10 to 15
knots on Monday and Tuesday with a further increase to around 20
knots on Wednesday. However, very high rainfall rates of 3 to 4
inches per hour with the strongest convection could lead to some
localized flash flooding issues each day next week. The highest
threat will be for urban drainage systems that could be easily
overwhelmed by these excessive rainfall rates.

&&

.AVIATION...
(06Z TAFS)
Issued at 300 AM CDT Thu Jun 13 2024

VFR conditions at at all terminals currently and likely through
the rest of the period. Can`t rule out some very isolated
convection along the immediate LA coast tomorrow, but not enough
confidence to include VCTS for any terminals.

&&

.MARINE...
Issued at 300 AM CDT Thu Jun 13 2024

Through Saturday, high pressure building over the waters will keep
a light south to southeast flow of 10 knots or less in place. Seas
of 2 feet or less will accompany these lighter winds. The only
concern will be the threat of isolated to scattered thunderstorm
activity that could produce some waterspouts and gusty winds. By
Sunday, the high will shift to the east and a developing area of
low pressure in the Bay of Campeche will lead to a tighter
pressure gradient across the northern Gulf. East and southeast
winds will increase to 10 to 15 knots on Sunday, 15 to 20 knots on
Monday, and then to 20 to 25 knots on Tuesday. Seas will respond
to these increased winds and should be in the 5 to 7 feet range
over the open Gulf waters by Tuesday. The prolonged nature of
these stronger onshore winds will lead to some minor coastal
flooding issues by Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  92  68  96  71 /  10  10  10  10
BTR  93  71  96  74 /  10  10  10  10
ASD  93  73  96  75 /  20  10  10  10
MSY  91  77  94  78 /  30  10  20  10
GPT  92  76  93  78 /  20  10  10  10
PQL  93  73  94  75 /  20  10  20  10

&&

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

$$

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