Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
FXUS64 KLIX 280111
Area Forecast Discussion
National Weather Service New Orleans LA
811 PM CDT SAT AUG 27 2016
The precipitable water value remains above normal at 2.15 inches
this evening. While there are pockets of drier air in the lower
levels, the largest dewpoint depressions are above 350mb. With the
sunset, showers and thunderstorms are showing a downward trend as
is typical even with MLCAPE of 1500 J/kg. Winds in the low levels
are from the east with a layer average speed of about 15 knots and
then are primarily from the south in the middle and upper levels.
00z flight info: A routine flight that ascended for 104 minutes
bursting near Robert at a height of 20.6 miles above the ground 34
miles downrange from the office.
.PREV DISCUSSION... /issued 337 PM CDT SAT AUG 27 2016/
No major changes in thinking through Tuesday as a broad upper
level low lingers over the western Gulf. This slow moving
upper level feature will continue to bring increased rain chances
to the area as a series of vorticity lobes slides across the
central Gulf Coast. With each passing vort lobe, increased forcing
and a surge of deeper tropical moisture should overspread the
region. As a result several rounds of shower and thunderstorm
development will be possible. There will continue to be a fairly
sharp gradient when it comes to available moisture with higher
precipitable water values and mean mixing ratios along and south
of the I-10 corridor and lower values farther inland. This supports
the continued idea of likely POP of 60 to 70 percent along and
south of I-10 and 30 to 50 percent for areas north of I-10
through Monday. Daytime highs will be slightly cooler than normal
tomorrow and Monday due to the increased convective activity and
related cloud cover reducing solar insolation.
The upper low should push slightly more to the west by Tuesday.
Precipitable water values and lift across the area will decrease
slightly, and expect to see rain chances fall back into the 30 to
50 percent range across the entire forecast area Tuesday
afternoon. Rain chances will be highest over western zones where
moisture profiles and forcing aloft are greatest. With slightly
less convective coverage, daytime highs should climb back into the
lower 90s which is closer to seasonal norms.
There is some significant disagreement in the forecast heading
into the latter part of next week. At this time, have opted to go
with a persistence forecast which closely mirrors the GFS. The
caveat being that a tropical wave is expected to enter the Gulf
by Monday and will need monitoring until it either dissipates or
In the wake of the departing upper level trough, a broad upper
level high is expected to build across the Gulf South. This upper
level ridging should linger over the region through the end of the
week, and a more typical late August weather pattern is forecast
to take hold. As a result, the forecast calls for a 20 to 30
percent chance of convection firing up from late morning through
the afternoon hours when overall instability peaks due to daytime
heating. Any convection should rapidly die off after sunset, and
have dry conditions in place for the overnight hours over land.
The reverse cycle is expected over the waters with convection
peaking overnight and early morning before becoming more isolated
in the afternoon hours.
Highs will also warm into the middle 90s by Wednesday and remain
in that range through Saturday due to the combination of weak
subsidence aloft and stronger solar insolation through the day.
Overnight lows should also warm up a bit, and expect to see
temperatures in the lower 80s along the coast during the extended
period. With dewpoints still in the 70s across the region, heat
advisories may be needed for the latter half of the week.
Outside of convection look for VFR conditions for the
most part. Convection will likely impact most terminals. The one
location that could stay convection free may be MCB as storms try to
stay more confined to the coast. Convection should also wane this
evening with mainly just mid and high clouds overnight. /CAB/
The persistent easterly winds of 10 to 15 knots will
continue but could increase to near 15 possibly 15 to 20 knots
tomorrow and exercise caution headlines may be needed. As mentioned
earlier the easterly winds are helping to drive up the tides which
are running about .5 to 1 feet above normal. Seas will remain in the
2-4 ft range through midweek. There remains much uncertainty with
respect to the tropical wave that should enter the Gulf through the
FL straights in the next day or so but if it moves deeper into the
Gulf or strengthens then conditions could be far different than what
is in the forecast for Wed-Sat. /CAB/
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 73 90 74 92 / 20 40 30 40
BTR 74 89 74 89 / 50 60 50 50
ASD 77 89 77 89 / 40 60 50 50
MSY 78 88 78 88 / 50 70 50 50
GPT 78 88 78 89 / 40 50 40 40
PQL 77 88 77 90 / 30 50 30 40