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

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FXUS64 KLIX 282037
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
337 PM CDT SUN AUG 28 2016

.SHORT TERM...

A slow moving upper level low currently over the far northwest
Gulf will continue to drift into Texas tonight and tomorrow. As
this occurs, a broad upper level ridge of high pressure will
spread to the west and become a much greater influence over our
region by Tuesday and Wednesday. A north-south gradient in terms
of POP will persist into tomorrow with more isolated coverage of
showers and thunderstorms expected across southwest Mississippi
and more likely coverage along and south of the I-10 corridor.
The convection is fast moving, so rainfall rates should be low
enough to not produce any significant flooding issues even with
the saturated antecedent soil conditions. Temperatures will be
near normal tonight, and remain slight below average during the
day tomorrow.

Heading into Tuesday and Wednesday, a strong upper level high will
be positioned directly over the Lower Mississippi Valley. Strong
subsidence or sinking air aloft will cause the atmosphere in the
mid and upper levels to dry out and warm up. This should produce a
fairly strong temperature inversion in the mid-levels. This
inversion will greatly reduce the amount of instability in the
atmosphere and stunt cloud development. Given these conditions,
only have a slight chance of rain in place for both days.
Temperatures will also rise into the middle 90s each day due to
the combination of subsidence and strong solar insolation. With
dewpoints lingering in the lower 70s at the surface, heat index
values of 100 to 105 degrees will be possible Tuesday and
Wednesday.

Invest 99L will also slowly drift to the west and should be
somewhere over the east-central Gulf of Mexico by Wednesday
afternoon. Fortunately, with the strong upper level ridge parked
over us, this system should remain well displaced from the
forecast area. The biggest impact will be a sustained easterly
wind of 15 to 20 knots that could push tides up 1 to 2 feet above
normal on east facing shores.

.LONG TERM...

The forecast for the latter part of the workweek and into the
weekend continues the trend of ridging aloft remaining parked over
the area. There could be a weak reinforcing backdoor front that
slips into the area Friday and slowly dissipates along the coast
on Saturday and Sunday. This front is associated with a fairly
strong upper level trough that will dig into the eastern seaboard,
and this trough will also be the feature that picks up Invest 99L
and drives it across northern Florida into the eastern Atlantic.
All of the model guidance is in good agreement on this occurring.

Our weather conditions will not vary much from those seen on
Tuesday and Wednesday with warm temperatures in the middle 90s
each afternoon and a chance of some isolated to widely scattered
showers and thunderstorms. The thunderstorm chances should be
greatest on Friday and Saturday at around 30 percent as the weak
backdoor front slides in and stalls along the coast. Heat index
readings will remain between 100 and 105 degrees through this
period.

&&

.AVIATION...

Once again convection is the main concern. Outside
of convection look for VFR conditions for the most part. Convection
will likely impact most terminals through 3z and then could become
more confined to coastal terminal of SELA. Otherwise look for
mainly BKN to OVC mid level clouds through the night. /CAB/

&&

.MARINE...

A very persistent easterly wind of 15 to 20 knots should develop
tonight and then remain in place across the open Gulf waters
through Wednesday. This wind is the direct result of a ridge
sitting north of the area, and the low pressure associated with
Invest 99L. This east wind should also keep tides elevated on east
facing shores. As the tropical low moves into north Florida later
in the week a frontal boundary should move in from the north.
Winds will turn northerly and weaken to around 10 knots on
Thursday before turning westerly for the upcoming weekend. Seas of
3 to 6 feet can be expected through Wednesday, and these seas may
be even higher if the tropical low intensifies and produces a
large swell train in the Gulf. Seas should begin to diminish later
in the week and over the weekend as winds decrease and the
tropical low pushes out of the Gulf. 32

&&

.DECISION SUPPORT...

DSS code: Blue
Deployed: None.
Activation: None.
Activities: Flood recovery support

Decision Support Services (DSS) Code Legend
Green  = No weather impacts that require action.
Blue   = Long-fused watch, warning, or advisory in effect or
         high visibility event.
Yellow = Heightened impacts with short-fused watch, warning
         or advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
         tropical events; HazMat or other large episodes.
Red    = Full engagement for Moderate risk of severe and/or
         direct tropical threats; Events of National Significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  74  92  73  94 /  20  30  10  20
BTR  74  91  72  93 /  30  40  20  20
ASD  77  90  77  91 /  30  40  20  20
MSY  78  89  79  92 /  40  50  30  20
GPT  78  90  78  91 /  30  30  10  20
PQL  77  91  77  92 /  20  20  10  20

&&

.LIX Watches/Warnings/Advisories...
LA...None.
GM...None.
MS...None.
GM...None.
&&

$$

32


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