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

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FXUS64 KLIX 220914
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
414 AM CDT Thu Apr 22 2021

.SHORT TERM (Today through Saturday Night)...High pressure begins to
move east today allowing moisture to begin streaming back into the
area along with a warm front Friday. This will be the first area
of two fronts that we will need to focus on with respect to
severe wx. The warm front begins to move through the area around
noon Friday with TS development along and south of the boundary.
Numbers that buoy severe thunderstorms are moderate to high and
some are impressive but conditional, but it shouldn`t take much
to get something going, so thoughts are that we will see several
make it to this severe category between Friday and Saturday. These
severe wx numbers do not look good until the warm front boundary
passes a location, but once in the warm sector, there is plenty of
instability. Helicity values are off the charts for 0-3km of
550-650 and all storms being sfc based will make tornadoes
possible. Steep mid-level lapse rates and low Wet Bulb0 numbers
give rise to large hail. Damaging winds will be a possibility as
well with these, so all modes will be possible Friday afternoon
and evening. Then the cold front moves through Sunday and will
posses the same environmental instability as the warm front
provided to keep the threat for severe thunderstorms going through
Saturday afternoon.

.LONG TERM (Sunday through Wednesday)...A deep layer ridge axis and
strong subsidence throughout the atmospheric column will keep skies
clear, humidity values low, and temperatures near to slightly above
normal during the day.  Highs will easily climb into the lower to
middle 80s both Sunday and Monday.  Temperatures Sunday night will
cool into the upper 50s and lower 60s. An increase in low level
moisture advection and dewpoints is anticipated by late Monday night
as the ridge axis begins to push a bit to the east and this will
keep lows a bit warmer in the lower to middle 60s.

Conditions will begin to transition back to a more unsettled weather
regime on Tuesday, but a strong mid-level capping inversion during
the day will prohibit any convection from initiating.  Below this
inversion, strong lapse rates will promote the development of a
scattered to broken strato-cumulus field, and a few light marine
layer showers may develop by the late afternoon hours.  Temperatures
will remain warmer than average with highs climbing into the middle
80s at many locations.  Only the coast should remain slightly cooler
in the upper 70s and lower 80s.

By Tuesday night and Wednesday, the region will be under the full
influence of a strong longwave trough axis kicking out of the desert
Southwest.  Strong difluent flow and favorable jet dynamics aloft
will promote stronger lift and increased cloud development through
the overnight hours.  There will continue to be some weakness in the
mid-level lapse rates as a pool of drier air lingers, but enough
dynamic forcing will be in place to support some isolated shower and
thunderstorm activity over the northwest portion of the forecast
area.

The main thrust of the longwave trough will be felt on Wednesday as
a negatively tilted trough axis and fairly strong front sweep
through the area.  Strong forcing and ample thermodynamic support
with temperatures warming back into the lower to middle 80s will be
in place to support scattered shower and thunderstorm activity
through the day and into Wednesday night. There are still some
timing differences between the models on exactly when the front will
sweep through the area, but in general a rather unsettled day can be
expected. Currently, shear profiles would suggest the potential for
another round of severe convection in the area, but it is too far
out to pinpoint the timing or exact convective mode of any severe
thunderstorms.  We will continue to monitor this potential severe
thunderstorm threat over the coming days. PG

&&

.AVIATION...VFR will continue at all terminals through tonight.
Winds will shift from the northeast to the southeast during the day
today and could gust over 15 knots at times at KNEW, KGPT, KHUM, and
KMSY.

&&

.MARINE...
Moderate northerly flow will become easterly today as high pressure
builds east. Caution statements will remain through today as winds
ease. But moderate southeasterly flow expected on Friday, before
shifting southerly and increasing to moderate to strong overnight
ahead of another cold front. Any periods where winds will be below
15 knots will be brief for most of the open waters over the next
several days, with no real respite until the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  69  51  73  62 /   0  10  50  90
BTR  70  55  75  65 /   0  10  70  80
ASD  70  54  75  65 /   0  10  50  70
MSY  69  59  76  68 /   0  10  50  70
GPT  67  56  72  65 /   0   0  30  70
PQL  70  53  74  64 /   0   0  20  70

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

$$


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