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

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FXUS64 KLIX 252055
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
355 PM CDT THU AUG 25 2016

.SHORT TERM...

The fast moving upper level vort lobe passing through the region
today will quickly push to the west as it rotates around the
periphery of a strong upper level ridge parked across the
Tennessee Valley. Before this upper level energy clears the area,
lingering scattered convection can be expected over the western
half of the forecast area through the evening hours. Conditions
should quickly clear out later tonight as increased negative
vorticity advection and subsidence develops in the mid and upper
levels. A surge of drier air in the mid-levels is also expected
which should effectively bring an end to the rainfall as PW values
drop to 1.5 inches or less. This much more stable airmass will
linger over the area tomorrow, and have much lower rain chances of
10 to 30 percent in place. Rain looks to be most likely along the
coast where some seabreeze interactions could spark off isolated
showers and thunderstorms. Temperatures will also be a bit warmer
tomorrow due to the subsidence aloft and lack of convection. Highs
should easily climb into the lower to middle 90s.

Another lobe of increased upper level vorticity and overall lift
will overspread the region on Saturday and remain in place on
Sunday. This fairly vigorous upper level trough will also bring a
pool of deeper tropical moisture into the region. Precipitable
water values should rise from 1.5 inches to around 2.25 inches by
Saturday afternoon as this deep tropical moisture advects in.
Overall instability will also increase, and expect to see
scattered to numerous showers and thunderstorms develop from late
morning through the evening hours. There should be a gradient in
the moisture profile with higher atmospheric moisture content
south of I-10 and lower amounts over the northern zones through
the weekend. Have likely POP of around 60 percent south of I-10,
and only chance POP of 20 to 30 percent for the northern zones.
Temperatures will generally cool back into the upper 80s and lower
90s as this system moves through the convective coverage
increases.

.LONG TERM...

Heading into next week, both the ECMWF and the GFS indicate that
any potential tropical system should remain east of the region.
Given this agreement, have opted to stick with a drier forecast as
strong mid and upper level ridging develops across the Lower
Mississippi Valley. The strong ridging aloft should warm and dry
out the mid and upper levels of the atmosphere resulting in lower
instability and lower atmospheric moisture content. At this time,
have went with POP of 20 to 30 percent for each day next week.
Temperatures should also climb due to the sinking air aloft and
increase in solar insolation with highs easily climbing into the
middle 90s each day. Fortunately, with dewpoints somewhat lower
heat index values should remain below advisory levels.

&&

.AVIATION...

Scattered to numerous showers and thunderstorms are expected across
most of the forecast area this afternoon. will maintain and insert
tempo ts for all taf sites through 22z except MCB. The convection is
expected to diminish by 23z. areas and taf site that received
rainfall this afternoon may experience a brief period of mvfr
conditions due to patchy fog between 11 and 13z friday. 18

&&

.MARINE...

A general east wind of 10 to 15 knots is expected across the
coastal waters through the weekend. Seas will generally range from
1 to 3 feet in this easterly flow. Heading into early next week,
there is the potential of a tropical low moving through the
eastern Gulf of Mexico. The forecast shows some slightly stronger
easterly flow of 15 to 20 knots and seas of up to 4 feet for
Monday into Monday night. The global models indicate any system
should be moving out of the eastern Gulf by Tuesday or Wednesday
allowing high pressure to build back in from the north. A general
west wind of 10 to 15 knots is expected for the middle of next
week. Seas should also remain in the 1 to 3 feet range during this
period.

&&

.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  73  93  73  92 /  30  20  10  20
BTR  73  93  74  90 /  30  10  10  40
ASD  75  92  76  91 /  30  10  10  50
MSY  79  92  78  90 /  30  20  10  50
GPT  76  92  76  91 /  20  10  10  30
PQL  76  93  75  91 /  20  10  10  20

&&

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

$$



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