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

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FXUS64 KLIX 262046
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
346 PM CDT Wed Apr 26 2017

.SHORT TERM...
Cold front with a line of thunderstorms is moving through the
ArkLaTex region at this time but convection on the southern extent
is struggling to materialize due to strong capping in place in the
downrange environment. This is evident on the KLIX radar
presentation of the doughnut ring of brighter reflectivities being
collected due to super-refraction of the beam through this stable
layer between roughly 2100-9900 ft. A line of showers and
thunderstorms is still expected overnight with upper level
precipitation softening the cap eventually to allow for better
convective process with frontal forcing overnight. Primary window
still appears 9 pm in the New Roads and Baton Rouge areas, 10 pm
McComb to Hammond, 11-midnight New Orleans and Northshore,
midnight-1 am I-59 corridor, 1-3 am Gulfport/Biloxi, and closer to
4 am Pascagoula. Drier air works into the area but may have a few
straggler showers at daybreak before the area truly clears, hence
a 20 percent PoP in the eastern half at daybreak. Not much in the
way of wake high pressure whereby return flow onsets a warm
frontogenesis process overnight Thursday night into early Friday
morning that may produce a few showers in the coastal areas at
daybreak that advance quickly northward through the forecast area
by mid-morning. Deep fetched onshore flow then prevails for much
of the day Friday through Sunday. Went with bias correct consensus
model guidance on temperatures.

.LONG TERM...
The next main weather feature will be next deepening low pressure
system over the Plains States that will be bringing inclement
weather to the forecast area Sunday. Timing still favors mid to
late afternoon hours through the evening hours. Will continue to
show close to 80% rain chance with decent QPF from a more
efficient rain process ahead of the front. Front clears the area
in the pre-dawn hours Monday with cooler and drier high pressure
building over the area for Monday through Tuesday, before the
process of another warm front followed by cold front takes place
middle of next week. 24/RR

&&

.AVIATION...
A band of convection will push across the area between 00z and 08z.
Convection is most likely from 00 to 04z around KBTR, KHDC, and
KMCB. From 04z through around 08z, convection should impact the
remainder of the terminals. Have placed -TSRA and MVFR ceilings and
visibilities in the forecast to reflect this convective risk during
this period of time. After 08z, conditions will improve as winds
shift to the west and northwest and ceilings gradually lift. Expect
to see VFR conditions at all of the terminals after 14z tomorrow.
32

&&

.MARINE...
Strong onshore flow of 20 to 25 knots will persist over most of the
coastal waters tonight as a strong low pressure system passes
through the mid-Mississippi Valley.  Small Craft Advisories have
been posted for most of the waters tonight with only the tidal lakes
remaining in exercise caution range of 15 to 20 knots.  Seas will
remain very rough with significant wave heights of 4 to 7 feet in
the open Gulf waters and 2 to 5 feet in the sounds and lakes.
Conditions will briefly improve tomorrow as the low pulls out of the
area and high pressure settles over the Gulf South.  Winds should
turn more variable and fall to 10 knots or less.  Seas should also
decrease to 3 to 5 feet in the Gulf and 1 to 2 feet in the sounds
and lakes.

However, another round of strong onshore winds is expected to
quickly develop tomorrow night and gradually increase through the
weekend as a low pressure system intensifies over the Plains states.
Expect to see sustained winds of 20 to 25 knots on Friday and
Saturday before rising to 25 to 30 knots on Sunday.  Seas will also
increase from 4 to 7 feet on Friday to 9 to 12 feet on Sunday. Above
normal tides can be expected over the weekend due to the persistent
onshore flow.  A cold front associated with the front will sweep
through Sunday night and winds will shift to the northwest at 20 to
25 knots Sunday night into Monday morning.  As the high settles over
the area Monday afternoon, offshore winds should quickly diminish 10
to 15 knots and seas should decrease from 5 to 8 feet in the morning
to 4 to 6 feet by the afternoon. 32

&&

.DECISION SUPPORT...
DSS CODE...Blue.
DEPLOYED...None.
ACTIVATION...None.
ACTIVITIES...Monitoring severe weather potential tonight.

Decision Support Service (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 of severe weather;
         Nearby tropical events, HAZMAT or other large episodes
RED    = Full engagement for moderate risk of severe weather; Direct
         tropical threats; events of national significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  85  55  81  61 /  30  90   0  10
BTR  87  56  81  63 /  50  90  10  10
ASD  84  61  82  68 /  20  80  20  10
MSY  85  62  82  69 /  40  70  20  20
GPT  78  67  81  71 /  40  70  20  10
PQL  77  65  83  65 /  30  70  10  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 4 AM CDT Thursday for GMZ550-552-570-
     572.

     Small Craft Advisory until 7 AM CDT Thursday for GMZ555-557-575-
     577.

     Small Craft Advisory until 4 AM CDT Thursday for GMZ532-536-538.

MS...None.
GM...Small Craft Advisory until 4 AM CDT Thursday for GMZ552-570-572.

     Small Craft Advisory until 7 AM CDT Thursday for GMZ557-575-577.

     Small Craft Advisory until 4 AM CDT Thursday for GMZ536-538.

&&

$$

24/RR
32


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