Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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FXUS64 KLIX 270846

Area Forecast Discussion
National Weather Service New Orleans LA
346 AM CDT Mon Mar 27 2023


(Today through Wednesday Night)
Issued at 257 AM CDT Mon Mar 27 2023

A meandering frontal boundary currently located just north of the
CWA in south-central Mississippi and central Louisiana will drift
southward this morning in response to a cold pool left in the wake
of convective activity that occurred yesterday along the I-20
corridor. As the impact of this cold pool dissipates in the late
morning and afternoon hours, the front will stall along the I-10
corridor. Along the front, the combination of enhanced low level
moisture convergence and moderate instability as noted by MLCAPE
values of 1000 to 1500 J/KG will support the development of
scattered convection today. The peak timing for convection will be
in the afternoon hours when instability peaks and mid-level lapse
rates maximize at around 7.0 C/km. Overall, have stuck close to
the CAMS guidance concerning the convective activity late this
morning through the early evening hours when convective conditions
are more favorable, but disregarded the overly aggressive CAMS
solutions in the early morning hours due to a combination of the
front starting to move into the area at that time and a lack of
instability. The aforementioned steep mid-level lapse rates will
be supportive of some strong to severe thunderstorms forming this
afternoon as some deeper convective cores should easily develop.
Speed shear of 40 to 50 knots in the effective layer will also
keep updrafts well tilted, and also allow for the convection to
propagate downstream into more favorable thermodynamic
conditions. The primary concerns will be large hail and the
downward transport of some stronger winds aloft during the
afternoon hours.

Convective activity will briefly wane to a few showers and
thunderstorms in the late evening hours as MLCAPE falls below
1000 J/KG, but this respite in unsettled weather will be very
brief. Late tonight and early tomorrow morning, a northern stream
shortwave trough axis and associated surface boundary will quickly
slide into the area. Increasing deep layer forcing will combine
with ample moisture and the favorably steep mid-level lapse rates
already in place to produce scattered to numerous showers and
thunderstorms in advance of the frontal boundary throughout the
day tomorrow. The front and convection will first peak in the
morning hours across the northwest half of the forecast area, and
then transition towards the coast by the afternoon hours. The
convective threat should push into the offshore waters by the
evening hours. Overall, the severe threat will remain the same as
seen on Monday due to continued steep mid-level lapse rates and
speed shear of 40 to 45 knots in the effective layer. Large hail
and strong damaging wind gusts will once again be the primary
concern on Tuesday with the deepest convective cells. Given the
more extensive convective coverage expected tomorrow, high temperatures
should be closer to average in the mid to upper 70s.

Although a cooler and more stable airmass will advect into the
area Tuesday night into Wednesday, a passing southern stream
shortwave and southwesterly flow in the mid-levels will keep skies
overcast into Wednesday morning. However, by Wednesday afternoon,
skies should rapidly clear as the southern stream system pulls to
the east and deep layer ridging builds into the area. Weak cold
air advection will also take hold by Wednesday, and this will
allow temperatures to cool back to more normal readings for late
March with highs in the low to mid 70s and lows in the 50s.


(Thursday through Sunday) Issued at 257 AM CDT Mon Mar 27 2023

A quiet but warm start to the extended forecast as we briefly sit
under ridging with surface high pressure just east of the area. High
temperatures will be near the climate norms to start, but by the end
of the week and into the weekend they will climb to the mid 80s
which is around 10 degrees above average. We will also have
southerly flow into Friday and to start the weekend, so it may feel
pretty summer-like outside.

Our next chance for some showers and storms will arrive through
Friday, though most of this may stay north of our area. This starts
as a shortwave trough swings across the Central Plains and up
towards the Great Lakes region with a cold front forming at the
surface. This front will move into our area Friday night into early
Saturday. The globals divert quiet a bit with this system, so going
to wait for those to come into agreement more before getting into
the details of this system. The GFS wants to bring the front all the
way through the area, while the Euro wants to stall it over us. For
now, left in some lower-end PoPs early in the weekend. Whether the
front stalls or goes through, it should bring us some brief relief
from the humidity.


(06Z TAFS)
Issued at 257 AM CDT Mon Mar 27 2023

The primary concern today will be lingering low ceilings through
the afternoon hours.  These low ceilings are the result of a warm
and humid airmass moving over cooler nearshore waters. As the
warmer air moves over the cooler waters, it cools slightly to the
dewpoint and condenses out into a fog and stratus bank.
Fortunately, stronger boundary layer flow will prohibit dense fog
development, but ceilings of 300 to 800 feet are expected at most
of the terminals through around 15z.  After 15z, ceilings should
start to lift into MVFR range of 1500 to 2000 feet. Some scattered
convection will be possible this afternoon, especially for
terminals along the I-10 corridor including GPT, ASD, NEW, and
MSY as a weak frontal boundary stalls along this corridor. Any
convective impacts are expected to be short-lived.


Issued at 257 AM CDT Mon Mar 27 2023

Overall, fairly benign conditions will be in place through
tomorrow morning with prevailing southerly flow of 5 to 10 knots
and seas of 2 feet or less expected. However, a cold front will
slide through the waters tomorrow afternoon, and this will induce
a period of stronger northerly winds approaching 20 knots Tuesday
night. These small craft conditions will be very short-lived as a
high pressure system builds in on Wednesday. Winds are expected to
veer to the east and decrease in speed to 10 to 15 knots by
Wednesday night and Thursday. Seas will also decrease from 4 to 6
feet Tuesday night to 2 to 4 feet by Thursday. Another approaching
area of low pressure will increase the pressure gradient across
the coastal waters on Friday, and this could push winds back into
the 15 to 20 knot range through Friday night.


MCB  81  61  73  48 /  10  60  60  10
BTR  83  66  74  53 /  10  60  60  10
ASD  82  65  76  53 /  40  50  80  20
MSY  80  67  75  57 /  40  40  80  20
GPT  78  65  74  53 /  50  50  80  30
PQL  80  65  75  51 /  40  40  80  30




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