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

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000
FXUS64 KLIX 280838
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
338 AM CDT Sun May 28 2017

.SHORT TERM...

One more day of a broad upper level ridge remaining in place
across the forecast area and providing enough subsidence aloft to
cap off most convective activity. At worst, some isolated showers
and thunderstorms may develop where the cap is weakest across
Southwest Mississippi and the adjacent Louisiana Parishes during
peak heating this afternoon. Otherwise, mostly cloudy skies this
morning should give way to partly cloudy skies by the afternoon,
and temperatures should easily climb to near 90 degrees.

The ridge axis will shift away from the area and more toward the
eastern Gulf and Florida tonight. As this occurs, a broad
positively tilted trough axis and associated frontal boundary
will sink into the region from the north. Any lingering mid-level
cap will quickly erode overnight, and expect to see some
convective activity initiate in a region of favorable jet dynamics
during the late overnight hours across the north and west parts
of the forecast area. Have included a mention of likely POP for
areas of Southwest Mississippi where the combination of ongoing
convection advecting in from the north, and new convection
initiating to the southwest and also advecting in is expected. The
remainder of the area should see chance POP coverage during the
late overnight hours. Temperatures will remain warm and muggy with
overnight lows only cooling into the middle to upper 70s.

Monday and Tuesday look to be very unsettled due to a combination
of a weak low level boundary stalling over the region, favorable
upper level dynamics that maximize lift across the region, and
ample instability throughout the atmospheric column as noted by
CAPE values in excess of 2000 J/KG and lifted indices of around
-5C. Have kept in likely POP of 60 to 70 percent for the area both
 on Monday and Tuesday. POP should fall back into chance range
 Monday and Tuesday nights as overall instability decreases due to
 loss of daytime heating. There could be a few strong to possibly
 severe thunderstorms tomorrow due to some increased directional
 wind shear in the lowest 6km of the atmosphere. If a stronger
 storm does develop, the primary concern would be for some
 damaging wind gusts to occur. Temperatures will be cooler both
 Monday and Tuesday due to the increased cloud cover and
 convection around with highs climbing into the middle 80s each
 day.


.LONG TERM...

Heading into the latter part of the week a transition to a more
typical Summer regime is expected with diurnally induced
convection possible each day. The coverage should be highest on
Wednesday due to the weak low level boundary still lingering over
the area as it slowly dissipates and some weak forcing aloft
associated with a weak vorticity maxima sliding in from Texas.
Expect to see fairly numerous showers and thunderstorms from late
morning through the afternoon hours due to this with coverage
greatest north of the I-10 corridor. Temperatures will easily
climb into the upper 80s Wednesday afternoon after cooling into
the upper 60s and lower 70s Tuesday night. As this occurs, CAPE
values will surge back to between 2000 and 3000 J/KG across most
of the region. Highest instability values will be over inland
portions of the CWA resulting in the higher POP forecast for that
area. Convective activity will decrease in coverage Wednesday
evening, and only expect isolated convective activity during the
overnight hours of Wednesday night as lows cool back into the
upper 60s and lower 70s and CAPE values fall below 500 J/KG.

Thursday through Saturday will be very typical days for early June
with highs near normal in the upper 80s and lows in the lower to
middle 70s. Diurnally forced convection will be possible each day,
and have a general 20 to 40 percent chance of thunderstorms in the
forecast from late morning into the afternoon and early evening
hours when instability is maximized. Surface based CAPE should
rise to between 1500 and 2500 J/KG each day, and the convective
temperature will be easily reached by late morning. Expect to see
a seabreeze boundary develop and push inland. This boundary will
in general serve as the focus for convective initiation, and have
the highest POP for areas north of the I-10 corridor where the
boundary should be located by the late morning and early afternoon
hours. Overall, a very typical Summer pattern for the latter part
of the week.

&&

.AVIATION...

MVFR conditions at all terminals with cigs at or below 2500 ft this
morning. Cigs will continue to drop to IFR levels at some terminals
toward daybreak. Conditions will begin to improve after sunrise and
should be VFR again at most sites by 16z. Almost a carbon copy
tonight with ceilings with more extensive cloud cover and depth.
There will also be an increase chance for sh/ts to begin overnight.
Most of this activity should hold off until after midnight.

&&

.MARINE...

Expect general onshore flow of 10 to 15 kts to persist through the
first half of Monday as high pressure remains centered over the
eastern Gulf of Mexico and Florida. Late Monday into Tuesday, a weak
front will stall near the coast resulting in a weaker pressure
gradient allowing winds and seas to relax. This front will also
result in an increase in shower and thunderstorm activity. The front
should be completely dissipated by Wednesday, with onshore flow of
10 to 15 knots remaining.

&&

.DECISION SUPPORT...

DSS CODE...Blue.
DEPLOYED...None.
ACTIVATION...None.
ACTIVITIES...Monitoring Mississippi River.

DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN  = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE   = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
         VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
         WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
         TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED    = FULL ENGAGEMENT FOR MODERATE TONIGHT RISK SVR
         AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
         SIGNIFICANCE

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  91  73  84  68 /  20  60  60  50
BTR  92  74  85  70 /  10  50  60  50
ASD  89  75  87  73 /  10  40  60  40
MSY  89  76  87  74 /  10  30  50  40
GPT  86  76  86  74 /  10  30  40  40
PQL  86  75  86  72 /  10  30  40  30

&&

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

$$

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