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

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FXUS64 KLIX 242205

Area Forecast Discussion
National Weather Service New Orleans LA
405 PM CST Sat Feb 24 2018

Today has been another warm one with temps at or near records, strong
onshore flow, and plenty of sun between cumulus clouds. Despite
the daytime instability only isolated spot showers have developed
this afternoon, likely due to the weak low level lapse rates and
elevated inversion seen on the morning sounding. Most areas will
remain dry this evening, though scattered showers and maybe a
thunderstorm are still possible.

The thinking for later tonight is that the complex of storms
developing now over far northeast Texas and southwest Arkansas
will push to the ESE. The line of showers and storms is expected
to sag south and approach the northern parts of our area after
midnight, though be weakening as it does. The stronger forcing and
shear remains well north of our area. The showers and storms will
also be encountering the weaker low level lapse rates and mid
level subsidence inversion closer to the Gulf Coast. Daytime
hours Sunday will likely involve scattered showers and some
embedded thunderstorms, mainly across the northern half of the
area. The cold front will hang up inland Sunday, with the boundary
providing the lift for precip. Gusty winds will be the main
marginally severe threat from any stronger storms. The rain and
increased cloud cover should keep temps a bit cooler in the 70s.

Sunday night into Monday morning another round of moderate to
locally heavy rain is expected as a secondary 500 mb shortwave
tracks over the Southern Plains. This will enhance convection and
rainfall on the boundary and help to finally push the cold front
into the northern Gulf Monday. Through Monday morning 2 to 4
inches of rain is still possible across the central Gulf Coast.
Any heavier storms or training cells could produce localized
flooding. An ongoing important consideration with the forecast
this weekend is situational awareness relating to the very warm
and moisture rich airmass in place. Conditions are still more
comparable to May or early June, with precipitable water in excess
of 1.5 inches.

Late Monday into Tuesday morning looks to be a dry period, but
onshore flow quickly returns. Scattered showers and storms are
possible Tuesday and Wednesday in onshore flow. The strong ridge
over the Gulf responsible for the exceptionally warm weather,
while suppressed south a bit, never loses its influence over the
central Gulf Coast. Therefore above average temperatures are
expected through Thursday, with only some cooling. In the long
range, there is model agreement that a vigorous shortwave trough
will approach the lower Mississippi Valley Wednesday night into
Thursday. Tropical air would again be in place so this upper low
and accompanying cold front will bring more chances for storms
midweek, some possibly strong. Temperatures closer to normal or
just a bit above are possible behind the cold front at the end of
next week.



Conditions should remain prevailing VFR this afternoon, however a
few airports may continue to have TEMPO MVFR category CIGS at times.
Isolated to locally scattered SHRA are expected through the evening
with a few TSRA possible. Given the low probability at an individual
TAF airport, have only carried VCSH through 06z Sunday. Lower MVFR
category CIGS are expected to return this evening, then IFR to LIFR
is likely after 06z Sunday through 12-15z Sunday morning along with
increasing chances of SHRA and some TSRA with associated lower VSBY.
The higher threat of the SHRA/TSRA, along with any erratic and
stronger winds, will be occurring in association with a cold front
that will be moving in from northwest to southeast overnight before
stalling out near or just inland from the coast on Sunday into
Sunday night. 22/TD


High pressure to the east and approaching cold front from the
northwest will maintain south winds of 15 to 20 knots across coastal
waters through this evening with seas up to 5 to 6 feet. Will
maintain "Small Craft Exercise Caution" headline through midnight
tonight. The pressure gradient will relax slightly overnight into
Sunday morning as the cold front approaches the coast and stalls
just inland. This is expected to maintain mostly south winds near 15
knots late tonight and south to southwest 10 to 15 knots on Sunday
through Monday which should allow the seas to slowly subside down to
2 to 4 feet across the coastal waters by Sunday afternoon. Most of
the thunderstorms that enter the coastal waters later tonight
through Sunday and Monday morning should be weakening, but cannot
rule out some stronger gusts and locally shifting winds with any
organized lines of storms.

Surface high pressure will build into the southeast states and
Atlantic coast region late Monday into Tuesday and that should nudge
the weak cold front south into the north Gulf coastal waters. Winds
will likely become weaker and shift to northwest, northeast then
east during the Monday and Monday night periods with speeds around
10 knots or less and seas of 2 to 3 feet. The high is expected to
shift east again heading into mid week which will bring a return to
southerly winds of 10 to 15 knots and higher wave heights again
Wednesday into Thursday. 22/TD


Deployed: None.
Activation: None.
Activities: Radar support and monitoring
marginal risk conditions.

Decision Support Services (DSS) Code Legend Green  = No weather
impacts that require action.
Blue   = Long-fused watch, warning, or advisory in effect or high
visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
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 risk of severe and/or direct
tropical threats; Events of National Significance.


MCB  62  67  55  72 /  90  90 100  30
BTR  64  72  59  74 /  80  90 100  30
ASD  69  75  63  74 /  40  70  90  60
MSY  71  78  66  73 /  40  70  90  50
GPT  71  74  65  72 /  30  60  80  70
PQL  69  77  63  74 /  30  60  80  70



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