Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
FXUS64 KLIX 261255
Area Forecast Discussion
National Weather Service New Orleans LA
755 AM CDT FRI AUG 26 2016
The sounding this morning indicates a couple differences from
yesterday. First there is an elevated inversion at 770 mb. This
could be from a bit of subsidence in the wake of the subtle
easterly wave from yesterday and slightly more influence from the
high pressure to the northeast. Much drier air is above that
inversion today, which has the overall PW down to 1.7 inches.
Winds remain generally easterly through the profile.
.PREV DISCUSSION... /issued 344 AM CDT FRI AUG 26 2016/
Tropical wave/Invest 99L is currently between the southeast
Bahamas and Cuba. Upper level high pressure currently centered
over Tennessee. At the surface, the Bermuda high extends into the
Carolinas, then southwest into Texas. Over the local area, clouds
from earlier convection are across the western half of the CWA.
Isolated showers and thunderstorms are mainly over our
southwestern coastal waters with one isolated dissipating
thunderstorm moving into Chandeleur Sound. Other than lower 80s in
a few coastal and New Orleans Metro locations, temperatures are in
Today looks to be the driest day through the weekend. We will see
with the 12z sounding whether the airmass will be as dry as
advertised. Precipitable water values on the 00Z sounding were at
2.2 inches, with both GFS and NAM BUFR forecast soundings bringing
that down to about 1.5 inches by 18Z. Satellite sounder data does
seem to support this. This wedge of dry air is not likely to have
a large north to south expanse, but should be centered close to
the Interstate 10/12 corridor. Will carry lowest POP in this area
today, but cannot preclude isolated thunderstorms even here.
Unfortunately, this dry air will be short lived with precipitable
water values returning to above 2 inches by Saturday afternoon. As
westward moving impulses move across this deep moisture, we will
be back to scattered to numerous afternoon thunderstorms for
Saturday and Sunday. Will be ranging POPs from 20-30 percent
across southwest Mississippi to 50-60 percent along the Louisiana
The drier airmass is likely to mean today will be the hottest of
the next 3 days with highs in the lower and middle 90s. Additional
clouds/precipitation likely to hold readings closer to 90 Saturday
and Sunday. 35
Unfortunately, the eventual forecast solution for the tropical
wave/Invest 99L is just as muddled this morning as it was 24 hours
ago. It seems that the amount of different solutions is only
limited by the amount of models run. As has been mentioned on
numerous occasions over the last several days, until there is an
actual complete circulation center, the models will struggle with
this system. And until shear relaxes, we may not see a center
develop. Doesn`t look like that will happen today. Add in the
potential for the mountains of Cuba to disrupt the wind
flow/circulation and the forecast is very uncertain. As always,
for the latest on Invest 99L, monitor products from the National
Until that situation becomes clearer, will keep with the blended
POP and temperature solutions. 35
VFR conditions are forecast to generally prevail at the terminals
through the TAF forecast period. Only isolated to scattered
convection is expected today, primarily during the afternoon hours.
Given the limited convection coverage expected today, it will not be
included in the terminal forecasts at this time. 11
A general moderate easterly flow is expected across the
coastal waters through the weekend and into early next week. Seas
will generally range from 2 to 4 feet. Heading into next week,
there is the potential of a tropical low moving through the
eastern Gulf of Mexico. At this time, there is considerable
uncertainty with regard to the development, if any, or track of
any possible system. 11
DSS code: Blue
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 93 73 92 73 / 30 10 20 10
BTR 93 74 90 74 / 20 10 40 30
ASD 92 76 91 75 / 20 10 50 30
MSY 92 78 90 78 / 20 20 60 40
GPT 92 76 91 76 / 20 10 30 20
PQL 93 75 91 75 / 20 20 30 20