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Area forecast discussion 
National Weather Service New Orleans la
401 am CDT Sat Sep 5 2015

Short term...

Another day of Summer weather across the forecast area...with
temperatures rising back into the lower to middle 90s and some
scattered diurnally induced convection from late morning through
the afternoon hours. It looks like convective chances will be
highest along the immediate coast of Louisiana this morning...and
then the risk of convection will transition more inland as the day
proceeds. It looks like some higher Theta-E values and increased
moisture pooling due to a convergent wind field will be found
over the far western part of the County Warning Area...closer to the Atchafalaya
basin...and would expect to see somewhat higher convective chances
in that region. Rain chances could increase to around 30-40
percent over the far western parishes...with 20 to 30 percent rain
chances for the remainder of the area today. Any convection will
be tropical in nature...with a quick hit of heavy rainfall for
several minutes and then a return to the hot and steamy
conditions that preceded the shower or storm.

A slowly retrograding upper level low will shift from the
southeastern Continental U.S. Into the eastern Gulf of Mexico Sunday through
Tuesday. Initially...the region will remain on the drier and more
stable side of the upper level low...and expect to see continued
Summer like weather across the area with scattered afternoon
convection and highs rising into the lower to middle 90s across
the area through Monday. However...on Tuesday...the upper level
low will become more centered over the forecast area. With the low
directly over the area...stronger forcing will take hold
aloft...and a plume of deeper tropical moisture will stream into
the region on the back of deepening southeasterly flow. As a
result...expect to see higher chances of rain along the coast and
have probability of precipitation boosted up to 40 percent. Cloud cover will also be on
the increase...and expect to see daytime highs fall back into the
upper 80s and lower 90s by Tuesday.

Long term...

Both the Euro and GFS indicate that the retrograding trough will
begin to weaken on Wednesday...as a deepening northern stream
trough begins to influence the region. There will still be ample
forcing and lift over the region as the combination of the
weakening system and increasing positive vorticity advection from
the approaching northern stream trough work in conjunction. As a
result...keep chance probability of precipitation in place during peak heating hours on
Wednesday.

By Thursday...the southern stream trough will have become fully
integrated into the much stronger northern stream trough as it
continues to dig into the lower Mississippi Valley. As this trough
deepens...a fairly strong cold front will form over the Southern
Plains and begin to approach the Gulf Coast. However...the
forecast area should be just far enough south to avoid impacts
from this front on Thursday. As a result...only expect to see the
same pattern of scattered mainly afternoon convection on Thursday.

The front will begin to influence the region more directly
Thursday night and especially on Friday and Saturday as a slow frontal
passage occurs. Expect to see several waves of showers and
thunderstorms move across the area as a series of weak upper
level impulses riding on the back of a jet streak aloft slide
across the Gulf south. The surface front will serve as a low level
focus for convection to initiate as these impulses aloft move
through. Given these conditions...have high end chance probability of precipitation in
place for the end of the week. Highs will be much cooler due to
the expected rainfall and cloud cover...with temperatures only
rising into the middle to upper 80s.

&&

Aviation...

Not as much ts coverage expected today. Will show thunderstorms in the vicinity for btr and
hdc since those two terminals should have the best chances of
receiving any activity. VFR conditions will be the norm through the
taf period for most sites. Will show some visible restrictions for
btr...hdc and hum since they may get rain today. If no rain...then
visible will only have minor MVFR restrictions. &&

Marine...

Pressure gradient is relaxed across the Gulf...fairly normal for the
late Summer doldrums. Deep tropical moisture and an upper trough will
remain over the Gulf. This weakness will keep higher chances of ts
activity in the coastal waters through much of the forecast. Winds
and seas will be higher near scattered ts. Wind gusts could be as
high as 30 knots with the strongest activity. Outside ts
activity...conditions will remain rather benign with a weak
pressure gradient. Nocturnal activity will be the most abundant
while there will be a general decrease in activity during the
late morning through late afternoon hours.

&&

Decision support...

Dss code....green.
Deployed...none.
Activation...none.
Activities...none.

Decision support services (dss) code legend
green = no weather impacts that require action
blue = long fused watch/warning/advisory in effect or high
visibility event
yellow = heightened impacts with short fused watch/warning/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 severe and/or direct
tropical threats; events of National significance



&&

Preliminary point temps/pops...
mcb 96 72 95 70 / 30 30 20 20
btr 92 73 95 73 / 30 20 20 20
asd 92 75 92 73 / 30 30 20 20
msy 91 77 92 76 / 30 20 30 20
gpt 91 76 90 74 / 30 20 30 20
pql 91 74 91 73 / 30 20 30 20

&&

Lix watches/warnings/advisories...
la...none.
GM...none.
MS...none.
GM...none.
&&

$$

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