LIX issues Area Forecast Discussion (AFD) at Sep 13, 11:41 PM CDT ...New AVIATION...200
FXUS64 KLIX 140441
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
1141 PM CDT Fri Sep 13 2024
...New AVIATION...
.UPDATE...
Issued at 945 PM CDT Fri Sep 13 2024
Generally, current forecast is on track. Might need to massage
hourly trends a bit at some point, but those wouldn't change the
wording of the forecast to any great extent.
&&
.SHORT TERM...
(This evening through Sunday night)
Issued at 255 PM CDT Fri Sep 13 2024
Strong negative vorticity advection and related subsidence will
continue to overspread the region tonight into tomorrow. The end
result will be continued dry conditions beneath partly cloudy
skies. Temperatures will be somewhat warm in the mid to upper 80s
and dewpoints in the mid 70s could push heat index values to
around 100 degrees in the afternoon hours. This will be the
biggest concern as communities continue to deal with power outages
in the wake of Hurricane Francine. Fortunately, overnight relief
is expected given the drier air in place. Lows will dip into the
upper 60s and lower 70s both tonight and tomorrow night.
A broad upper level low over the Tennessee Valley will drift
southward on Sunday, and this will lead to slightly higher rain
chances across the area as a weak frontal boundary slides in from
the northeast and stalls. The combination of increased low level
forcing along the front, some mid-level moisture advection, and a
series of weak vorticity maxima rotating around the parent upper
level low and across the area will all serve to produce scattered
convective activity Sunday afternoon. The increase in mid-level
moisture will help to raise PWAT values to more typical levels
seen in mid-September and also help to break down the mid- level
capping inversion that had been in place on Saturday. SBCAPE will
increase to around 1000 to 1500 J/KG Sunday afternoon in response
to these factors. Overall POP is forecast to peak near 30 percent
Sunday afternoon. Temperatures will be near normal with highs in
the mid 80s and lows in the upper 60s and lower 70s through Sunday
night.
&&
.LONG TERM...
(Monday through Thursday night)
Issued at 255 PM CDT Fri Sep 13 2024
Monday will be the most unsettled day in the long term period as
the broad upper level low over the Deep South drifts more into the
forecast area. The weak backdoor frontal boundary associated with
the upper level low will remain stalled over the area, and this
front will serve as the low level focusing mechanism for
convective activity as temperatures climb into the mid 80s and
SBCAPE values rise to around 1500 J/KG. Have opted to go with POP
values in the 30 to 50 percent range on Monday with the highest
values found across southern Mississippi and Northshore where deep
layer forcing will be most pronounced. This convection will be
very diurnally driven and highly dependent on daytime highs
climbing into the mid 80s.
Tuesday and Wednesday will see gradually decreasing convective
chances as the weak boundary over the area dissipates and the
upper level low lifts to the northeast. PWAT values will decrease
on Tuesday, but will still be near average. The end result will be
another round of widely scattered diurnally driven convection
Tuesday afternoon as highs warm into the mid 80s and SBCAPE rises
to between 1000 and 1500 J/KG. By Wednesday, a sharp increase in
negative vorticity advection into the area in the wake of the
departing upper level low will lead to greater subsidence and
lower rain chances. At best, an isolated shower or storm may
develop in the afternoon hours, but the overall forecast calls for
a largely dry day. Deep layer northwest flow will also allow for
drier air to advect in from the north, and this will also
contribute to lower PWATS and rain chances on Wednesday.
By Thursday, deep layer northerly flow will be in charge of the
area, and this will lead to a very stable environment across the
region. Little in the way of cloud development and no convective
activity is anticipated on Thursday and Friday as PWATS fall below
1.5 inches beneath a highly subsident airmass. Temperatures will
be slightly warmer on Thursday due to the increased sun and lower
dewpoints with highs warming into the upper 80s. Fortunately, the
dry air and clearer skies will also allow for overnight recovery
as lows dip into the upper 60s and lower 70s.
&&
.AVIATION...
(06Z TAFS)
Issued at 1131 PM CDT Fri Sep 13 2024
All terminals currently VFR. We can't totally preclude low clouds
and/or fog briefly around sunrise Saturday considering the light
winds and rather wet ground across the area, but with the drier
airmass and a significant period of sunshine on Friday, the threat
should be lower than Friday morning. We do expect some cumulus to
develop, but high level moisture arriving from the west may temper
development somewhat. That moisture is originating from weakening
East Pacific Tropical Storm Ileana in the Gulf of California, and
will only serve to filter sunshine a bit.
&&
.MARINE...
Issued at 255 PM CDT Fri Sep 13 2024
A rather benign stretch of weather is expected across the coastal
waters through the middle of next week as winds remain below 10
knots and seas remain below 2 feet through the period. These
calmer conditions will be driven by surface high pressure over the
area this weekend and a dissipating weak frontal boundary stalling
over the waters early next week. Winds will generally be from the
north through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 66 87 66 85 / 0 10 10 30
BTR 69 89 70 87 / 0 10 10 20
ASD 70 87 69 85 / 0 10 10 30
MSY 72 88 74 85 / 0 10 10 30
GPT 72 87 71 84 / 0 10 20 30
PQL 70 87 70 85 / 0 10 20 40
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
SHORT TERM...PG
LONG TERM....PG
AVIATION/UPDATE...RW
MARINE...PG
Source:
LIX issues Area Forecast Discussion (AFD) at Sep 13, 11:41 PM CDT ...New AVIATION...---------------
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