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

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FXUS64 KLIX 072038

Area Forecast Discussion
National Weather Service New Orleans LA
338 PM CDT Fri May 7 2021

.SHORT TERM (Tonight through Sunday Night)...A deep layer ridge
axis will remain in firm control of the forecast area through
tomorrow. Strong subsidence associated with this ridging will keep
skies clear and humidity values low through tomorrow. The clear
and dry conditions will also support a fairly large diurnal range
with lows dipping back into the 50s and lower 60s tonight before
warming into the low to mid 80s tomorrow.

The ridge axis will begin to shift to the east tomorrow night and
will be centered over Florida and the western Atlantic by Sunday
afternoon. As the ridge pulls to the east, southerly flow will
develop and allow for increased low level moisture advection into
the region. The rise in dewpoints Sunday night will allow for
warmer overnight lows tomorrow night with all locations only
dipping into the 60s. Skies will remain fairly clear during this
period, and the fog threat looks minimal due to stronger boundary
layer winds keeping the boundary layer fairly well mixed. On
Sunday, moisture advection will begin to deepen, but a pool of
drier air is still expected to linger in the mid-levels. The mid-
level capping inversion will prohibit convective initiation over
most of the CWA through the day with only a scattered cumulus
field expected. However, in the far northwest portions of the CWA,
generally west of McComb and north of Baton Rouge, some isolated
convection may develop as a vort max passes through north
Louisiana and into central Mississippi. Just enough upper level
omega and a slight increase in mid-level moisture should be
sufficient to weaken the mid-level cap and prompt a few showers
and thunderstorms by the late afternoon hours.

Model guidance is indicating a convective complex moving from
northern Louisiana into central Mississippi Sunday evening. This
convection will likely begin to push to the east and southeast
during the overnight hours as a strong cold pool and mesohigh
forms over central Mississippi, and the convective complex
follows the theta e ridge toward the northern Gulf. At this time,
expecting the convection to largely remain north and east of the
area for much of the night, but there is enough uncertainty to
warrant a high end chance POP of 50 percent over portions of
southern Mississippi. Outside of the convective threat, a very
muggy night is expected with dewpoints in the 60s and temperatures
in the lower 70s for most locations.

.LONG TERM (Monday through Thursday Night)...The convection mentioned
in the short term discussion will most likely impact the CWA
Monday, and have categorical POP in place to reflect this risk.
Bulk shear values remain limited, and the lack of strong winds
aloft will likely limit the severe potential of the convection.
The more likely scenario would be gusty winds and locally heavy
downpours as the convection moves through the area. There will
likely be a reduction in convective activity Monday evening as the
upper level energy driving the convection shifts to the east and
some weak negative vorticity advection takes hold of the region.
This break in convective activity will be short-lived as another
jet streak and upper level vort max move into the area later
Monday night. Temperatures will be near to slightly warmer than
average with highs in the mid 80s and lows near 70 Monday into
Monday night.

Tuesday will be another unsettled day as the aforementioned vort
max and jet streak slide through the region. Another convective
complex will likely form over eastern Texas and western Louisiana
late Monday night and the push across all of the forecast area
during the day on Tuesday. Have once again gone with a high POP
values of 60 to 80 percent to reflect this risk. Fortunately,
shear values remain limited, so the risk of severe storms will be
on the lower end. Rainfall will be the primary concern as
precipitable water values increase to near 2 inches, and some
areas could see a good 1 to 2 inches of rain over the northern
half of the CWA on Tuesday. Much like Monday night, the main
energy driving the convection will shift to the east and a lower
risk of thunderstorm activity is expected Tuesday night.

Wednesday will be another repeat of the previous two days in terms
of high POP and the risk of thunderstorms, as a strong northern
stream trough and an associated surface front slide into the
region. This system will have limited shear to work with, so the
risk of severe storms will remain low. There may be two rounds of
convection Wednesday into Wednesday night with the first round
during the day in the form a broad convective complex, and the
second round overnight in the form of a line of storms along the
cold front. By Thursday morning, the trough axis and front will
begin to pull out of the area, and gradually improving conditions
are expected through the day. POP values will decrease through the
morning hours, and expect to see only isolated showers and
thunderstorms over the eastern portions of the CWA by the
afternoon. Skies will also generally clear from west to east
through the day. By Thursday night, strong dry air advection and
subsidence in the wake of the trough should lead to clear skies
and and the end to any rain chances. Colder air will also advect
in and temperatures are forecast to dip into the 50s and lower


.AVIATION...The 00z TAF will indicate VFR conditions through
tomorrow evening as high pressure continues to dominate the Gulf
South. Winds will veer from the north- northwest today to the
east- southeast by tomorrow morning. PG


.MARINE...Fairly benign conditions are expected through tomorrow
night over the coastal waters, but an increase in gradient flow is
expected by Sunday. Southerly winds of 15 to 20 knots should
develop Sunday as a low pressure system passing north of the area
begins to induce a tighter pressure gradient over the Gulf of
Mexico. These winds will likely persist into Sunday night, but
should ease back into the 10 to 15 knot range for Monday and
Tuesday as the low pulls away and the pressure gradient over the
Gulf weakens. Another low will approach the area on Wednesday, but
a weaker high over the eastern Gulf should keep gradient flow
in the 10 to 15 knot range and seas at 2 to 4 feet. PG


MCB  52  84  63  85 /   0   0   0  10
BTR  56  85  65  86 /   0   0   0  20
ASD  55  82  66  85 /   0   0   0  10
MSY  63  83  69  84 /   0   0   0  10
GPT  58  78  68  81 /   0   0   0   0
PQL  53  79  63  82 /   0   0   0   0



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