Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
FXUS64 KLIX 301335
Area Forecast Discussion
National Weather Service New Orleans LA
835 AM CDT TUE AUG 30 2016
The sounding this morning again has a low level inversion in the
first 1500 feet and easterly flow up to 300 mb. The winds are up
to 20 kts just above the sfc. Overall though it is a much more
stable atmosphere than yesterday with mixed layer CAPE only 650
J/KG and PW near average at 1.7 inches. The central Gulf Coast is
beginning to see some subsidence effects aloft from building high
pressure. Little to no rainfall expected today.
.PREV DISCUSSION... /issued 336 AM CDT TUE AUG 30 2016/
TD 9 remains over the southeast Gulf of Mexico early this morning.
TD 8 is off the Carolina coast, and a weak cold front extends from
near Washington DC to Kansas City. At 500 mb...a weak upper low is
along the Texas coast with an upper high near the confluence of
the Ohio and Mississippi Rivers. Very little in the way of
convection, or even precipitation, over our area at present, both
land and marine. Also quite a bit less cloud cover than there was
24 hours ago. Early morning temperatures ran from the mid 70s to
The 06Z special sounding continued to show an easterly component
to the winds from the surface through about 325 mb, although the
only winds above 20 knots were between 925 and 720 mb. The
precipitable water value was 1.83 inches.
Not surprisingly, there hasn`t been much change in the forecast
scenario. Looks to be about another 36-48 hours of slow movement
before a developing trof over the Great Lakes and Ohio River
Valley begins the process of moving the system northeastward
across the Florida Peninsula. Moisture levels expected to remain
in the 1.6-1.8 inch range through Thursday, and with no real
organized source of lift, expect only isolated convective
development over land. Much of the land area with the possible
exception of lower Plaquemines Parish could remain dry through
Thursday. Marine areas might have a little better chance on
Wednesday night and Thursday as TD 9 passes east of our coastal
Even with scattered precipitation the last few days, most areas
have had little trouble getting into at least the lower 90s for
highs. As there is even less convection expected today, most
locations should make it into the middle 90s. Similar conditions
are expected for Wednesday and Thursday. The ECMWF solution would
indicate that we may even need to bump these highs up another
degree or two, especially Thursday.
As noted in the marine section of the discussion, will maintain
Coastal Flood Watch in its current configuration with the
expectation that it will probably morph into a Coastal Flood
Advisory later today. 35
As TD 9 moves across Florida on Friday, we should see one more day
with limited chances for convection and highs generally in the
lower and middle 90s. Beyond Friday, medium range models linger a
weak frontal system across the area through much of the remainder
of the holiday weekend as it slowly washes out. This will allow
for somewhat enhanced rain chances, in the 30-50 percent range
Saturday and Sunday, 20-30 percent on Labor Day. The higher rain
chances would infer more cloudiness and slightly lower
temperatures. Still around normal though. 35
TSRA coverage will be limited today. TAF sites that will have the
best chance of receiving a TS will be from ASD to HUM. But chances
will not be enough to show in any tempo group. VFR conditions should
be the most prevalent condition through 12z Wed.
Persistent moderate easterly flow will remain across the coastal
waters through Wednesday. These winds will be the result of a
tightening pressure gradient between a high located to the north of
the area and the lower pressure associated with TD 9 which is later
forecast to become a tropical storm as it moves into the middle Gulf
then turning to the northeast and moving across the northeast Gulf
into Apalachee Bay Florida. Exercise caution headlines will be
continued in the forecast for open gulf waters through Wednesday.
East winds will also keep tides elevated along most coastal
locations of Southeast Louisiana and Mississippi. Tides are
expected to run about a half to 1.5 feet above normal. As the
tropical system moves toward Florida, winds will turn northerly
and northwesterly and diminish to around 10 knots or less. Seas of
3 to 6 feet can be expected through Wednesday before subsiding
later in the week.
DSS code: Blue
Activities: Flood recovery support and monitoring TD 9
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 94 73 95 75 / 20 10 10 10
BTR 94 73 95 75 / 20 10 10 10
ASD 93 75 94 76 / 20 10 10 10
MSY 94 78 94 78 / 20 10 20 10
GPT 92 77 92 76 / 20 10 20 10
PQL 93 76 93 76 / 20 10 20 10
LA...Coastal Flood Watch from 7 PM CDT this evening through Thursday
morning for LAZ040-050-058-060>062-064-067>070-072.
MS...Coastal Flood Watch from 7 PM CDT this evening through Thursday
morning for MSZ080>082.