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

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661
FXUS64 KLIX 172051
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
351 PM CDT Thu Aug 17 2017

.DISCUSSION...It has been warm and humid today with multiple sites
seeing the heat index peak out around 106 to 108 but luckily none
have hit 110. As for convection there has been isolated storms so
far this afternoon mainly along and southeast of a line from Houma
to New Orleans. There is a thin line of decaying storms moving into
northwest sections of the CWA from the west. Both areas of activity
will dissipate around or before sunset.

We will quickly transition back to more rain tomorrow and especially
this weekend. Mid level ridge is still expected to slide to the west
as the trough axis move through the Mid and Upper MS Valley
tomorrow. As this ridge breaks down convection will become a little
easier to come by especially over the northeastern half/3rd where
the ridge will lose its grip first.

This weekend and through Monday we could begin to see scattered to
numerous showers and thunderstorms. First Saturday the ridge will
continue to be nudged to the west with a weakness over the region
between the ridge which will be over southeast TX and the other
ridge in the Atlantic off the FL/GA/SC coast. Combine that with
daytime heating and abundant moisture and we should see at least
scattered convection if not numerous by midday/early afternoon.

As we head into Sunday and Monday we will deal with the influence of
an upper low which is currently over and north of Hispaniola. Models
appear to be underdoing this currently but they all show it moving
into the central Gulf late Saturday night/early Sunday and a little
deeper. ECMWF has been handling this the best and will continue to
lean towards it for the forecast. ECM ensemble MOS is higher than
the op and agree with that so will go higher with the pops and abv
latest guidance values. It does look quite wet with deep moisture in
place, PWs near 2" and very rich moisture in the low levels with h85
theta e values around 340K. With that locally heavy rain is
definitely a possibility. Will need to continue to monitor this
especially if the upper low is a tad farther north in the north-
central Gulf, this would suggest even higher rain chances and likely
higher rain totals.

Heading into the middle of the week rain is still looking good
Tuesday as there will still be a weakness in place in the mid
levels. As we move into Wednesday rain chances should begin to come
back down a tad as the ridge begins to build back in.

&&

.AVIATION...Prevailing VFR with only isolated TSRA late
this afternoon so coverage not enough to mention. Ceilings generally
SCT at 030 to 040 this afternoon and evening.

&&

.MARINE...Second verse same as the first. High pressure will remain
in place with diurnal fluctuations being the main driver of winds.
With most nights look for a weak enhanced jet over the waters east
of the MS delta where winds could bump up to 10-15 knots at times.
Seas will remain in the 2-3 ft range or less.

&&

DSS code: Yellow.
Deployed: None.
Activation: None.
Activities: Heat Advisory.

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  74  91 /  10  40  10  50
BTR  76  92  76  91 /  10  30  10  50
ASD  76  94  76  92 /  10  30  20  60
MSY  78  93  77  92 /  10  20  20  60
GPT  77  91  77  89 /  10  40  30  60
PQL  75  93  75  91 /  10  40  30  60

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory until 7 PM CDT this evening for LAZ034>037-039-040-
     046>050-056>072.

GM...None.
MS...Heat Advisory until 7 PM CDT this evening for MSZ068>071-077-
     080>082.

GM...None.
&&

$$



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