LIX issues Area Forecast Discussion (AFD) at Jan 26, 5:28 AM CST ...New AVIATION...571
FXUS64 KLIX 261128
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
528 AM CST Sun Jan 26 2025
...New AVIATION...
.SHORT TERM...
(Today through Tuesday Night)
Issued at 233 AM CST Sun Jan 26 2025
A zonal flow pattern will dominate the upper levels today and
tomorrow, and a jet couplet moving through the Lower Mississippi
Valley today into tonight will induce enough deep layer forcing to
spark off showers across the northern half of the CWA. The best
forcing and highest overall threat of rain will occur tonight
across portions of southwest Mississippi and northern portions of
the Florida Parishes. Rainfall in these areas could approach an
inch in a few spots, but the prevailing rainfall totals should be
between one half and three quarters of an inch of rain. These
higher rain chances are also supported by persistent onshore flow
that will advect in a much warmer and more humid airmass through
the day. This is reflected by increasing precipitable water values
that are expected to rise from around an inch this morning to
nearly 1.5 inches by tonight. The zonal flow pattern aloft and
onshore flow will keep overall temperatures near to slightly
warmer than average.
The rain threat will end during the day tomorrow as the jet
couplet pulls away from the area. Instead, increasing negative
vorticity advection and subsidence associated with a building
upper level ridge will become the dominant feature from Monday
afternoon through Tuesday night. A weak front will also slip
through the area Monday afternoon and this will also pull some
drier air in from the north. The end result will be precipitable
water values falling to around 0.75 inches by Monday evening. Weak
cold air advection will also take hold with more average overnight
lows in the 40s and lower 50s anticipated. In the wake of the
front, a surface high pressure system will pass directly over the
area Tuesday into Tuesday night further lending to the deep layer
subsidence in place. Temperatures will modify a bit as the weak
thermal trough on Monday night shifts to the east, and readings
will be near average with highs in the 60s Tuesday afternoon and
lows in the upper 40s and lower 50s Tuesday night. One concern for
Monday and Tuesday night is that the combination of light
boundary layer flow and high humidity could support some patchy
fog development, especially in the Pearl and Pascagoula River
basins.
&&
.LONG TERM...
(Wednesday through Saturday)
Issued at 233 AM CST Sun Jan 26 2025
A spring-like period of weather is expected from Wednesday through
Saturday as the deep layer ridge axis becomes centered to the east
of the area. Strong and deep onshore flow will take hold and this
will allow a very humid and very warm airmass to move into the
area. Highs will easily climb into the low to mid 70s each day and
overnight lows will only cool into the 50s. Although this warm and
humid airmass moving over the cooler nearshore waters would
indicate the potential for fog, boundary layer winds will be far
too strong to support fog development. Instead, cloud cover will
be the rule through the period. Weak forcing aloft associated with
a difluent flow pattern will also support the development of
isolated to widely scattered showers on Wednesday and Thursday.
The greatest forcing will be across the northwest part of the CWA,
and this is where PoP values are highest at 20 to 30 percent.
Friday into Friday looks to be the stormiest day of the extended
period as a potent southern stream upper level low pressure system
begins to eject out of the Southern Plains and into the Ohio
Valley. A surface low and trailing front will form over northern
Texas Thursday night, and this front will sweep across the
forecast area Friday into Friday night as the parent low lifts
through the Ozarks. Ample moisture will be in place for the front
to interact with as it passes through the region with precipitable
water values approaching 2 inches. These values are well above the
99th percentile for this time of year, so there will be threat of
flash flooding with any heavier storms that form on Friday.
Fortunately, the threat of severe storms will be marginal at best
on Friday due to a lack of sufficient instability. MLCAPE values
could approach 500 J/KG in the afternoon hours, and this
instability will support some isolated thunderstorm activity
Friday afternoon and evening. If any storms get deep enough, they
will tap into decent speed and directional shear as a 40 to 50
knot low level jet develops over the region. Given that this is
expected to be a low cape and high shear event, the most likely
convective mode will most likely be linear.
Saturday will be a largely dry day as drier air and increased
subsidence aloft builds into the region behind the passing front
and longwave trough axis. There may be a few showers in the
morning across eastern zones, but clearing skies are expected for
the afternoon hours. Temperatures will remain mild as the airmass
moving in will have a Pacific based origin.
&&
.AVIATION...
(12Z TAFS)
Issued at 521 AM CST Sun Jan 26 2025
A mid-level cloud deck ranging from 4500 to 9000 feet this morning
will gradually build down between 18z and 00z as a weak cold
front approaches the area. MCB and BTR will be most impacted by
this front with scattered rain showers starting to impact MCB
after 18z and BTR after 06z. These rain chances are reflected by
PROB30 groups for these terminals this afternoon into the
overnight hours. At MCB, rain probabilities rise enough after 06z
to introduce prevailing rain conditions. Lowered ceilings will
accompany the rain and have included IFR ceilings of 500 to 800
feet in the forecast at MCB and BTR by 07z. At HDC, showers and
IFR ceilings will start to develop after 09z as the front
progresses further to the southeast. Elsewhere, VFR conditions
will continue to prevail until after 12z tomorrow. At MSY, IFR
ceilings will move in between 12z and 18z and rain chances will
briefly increase with the passage of the cold front.
&&
.AVIATION...
(06Z TAFS)
Issued at 233 AM CST Sun Jan 26 2025
All terminals now reporting ceilings in the FL060-080 range, and
these conditions will continue through the remainder of the night
into at least mid-morning Sunday. Beyond that point, could see a
few MVFR ceilings if there is enough sunshine through breaks in
the mid level clouds to allow some cumulus to develop. Not
carrying any mention of precipitation prior to 00z Monday in any
TAF. Will carry PROB30 in a few forecasts beyond that point, and
TEMPO MVFR at KMCB for several hours.
&&
.MARINE...
Issued at 233 AM CST Sun Jan 26 2025
Light winds and fairly calm seas are expected through Wednesday as
high pressure resides over the region. However, an increase in
gradient flow in advance of a deepening low over Texas is expected
to occur on Thursday and Friday. Winds will rise into exercise
caution range over the Gulf waters on Thursday and will likely
increase into advisory range of over 20 knots on Friday as the
gradient tightens in advance of an approaching front and a strong
low level jet forms over the area. Seas will respond and are
expected to rise to 5 to 7 feet in the open Gulf waters by Friday.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 65 51 61 43 / 30 70 50 0
BTR 69 54 64 45 / 20 50 50 0
ASD 66 52 64 47 / 10 30 30 0
MSY 66 53 64 50 / 10 20 20 0
GPT 63 52 62 47 / 0 30 30 0
PQL 64 51 64 46 / 0 30 30 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
SHORT TERM...PG
LONG TERM....PG
AVIATION...PG
MARINE...PG
Source:
LIX issues Area Forecast Discussion (AFD) at Jan 26, 5:28 AM CST ...New AVIATION...---------------
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