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

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000
FXUS64 KLIX 260835
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
335 AM CDT Tue Sep 26 2017

.SYNOPSIS...

Weak high pressure at the surface from the Great Lakes to
Louisiana. Aloft, a weak low is centered just off lower
Plaquemines Parish. Convection is pretty sparse this morning and
limited to the south shore and coastal waters. Temperatures
generally in the 70s at 3 am. Dew points in the 60s across the
northern half of the area, low and mid 70s to the south.

&&

.SHORT TERM...

Weak upper trough will drift eastward to near the Florida west
coast by Thursday evening. While weak upper ridging will develop
over the area, limiting rain chances beyond today, we still expect
a cold frontal passage Thursday. Deep convection likely to be
somewhat limited with a cap, or at least an isothermal layer or
inversion just above 500 mb on the GFS BUFR forecast soundings
locally. Instability also fairly weak for this time of year.
Previous forecaster had cut back on rain chances for today, and I
concur. Primarily closest to ECMWF guidance on POPs today. Pretty
much a dry forecast for most beyond today through Thursday. Not
much spread at all on temperatures and not going to make
significant changes there. 35

&&

.LONG TERM...

After Thursday`s frontal passage, an upper low will take up
residence over Florida for a few days, with the local area being
on the dry side. Little or no precipitation from Wednesday through
the first half of Sunday, before moisture returns. Will keep in
small mention of precipitation for Sunday afternoon into Monday.
Will trend toward the lower ECMWF numbers for low temperatures
Saturday and Sunday, otherwise will tend to stay near the
compromise solution.

Beyond the forecast period...an easterly wave moves across Florida
and the northern Gulf, which could have a wetting effect on the
forecast toward the end of next week. 35

&&

.AVIATION...

Ceilings will show up mainly when sh/ts are near. A CU field will
also show a BKN deck for a few sites at about BKN030. But this
should be short lived. Convective activity should show best
chances of development over the northern half of the area during
the afternoon hours today while the southern half of the area will
have best chances during the morning and these may be mostly
showers. Some lower ceilings look to show up overnight at the
BKN005 level.

&&

.MARINE...

High pressure will hold through Thursday. A cold front will
approach the northern gulf Friday morning. The cold front will
move back north by late Saturday. An inverted trough will move
west through the north central gulf Sunday. High pressure will
settle over the southeastern US starting late Sunday into the new
week. This occurs while a large broad weakness develops from the
southern gulf into the western Caribbean. The interaction between
the high strengthening over the southeast and the broad weakness
will cause the easterlies to become enhanced toward the latter
half of next week.

&&

.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, 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  88  69  90  69 /  30  10  10  10
BTR  89  69  90  71 /  30  10  10  10
ASD  88  69  90  70 /  30  10  10  10
MSY  88  72  89  74 /  40  10  10  10
GPT  87  71  89  71 /  30  10  10  10
PQL  88  68  90  68 /  30  10  10  10

&&

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

$$


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