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

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FXUS64 KLIX 290507

Area Forecast Discussion
National Weather Service New Orleans LA
1207 AM CDT Thu Jun 29 2017

Conditions are expected to deteriorate with a gradual lowering of
CIGS and VSBYS as rain and embedded convection spread over the
region overnight into Friday morning. Have prevailing -SHRA/SHRA
with VCTS at all the TAFS developing much of the next 24 hours.


.PREV DISCUSSION... /issued 401 PM CDT Wed Jun 28 2017/

A residual frontal boundary stalled across the northern Gulf
Coast will be the focus for high rain chances tonight through
tomorrow and again on Friday as the boundary lifts north. The
upper air sounding this morning showed precip water around 2
inches. This number will creep up about 10% overnight and tomorrow
morning with further column saturation (mainly in the upper
levels) and a slight increase in low level dewpoints. This will
push atmospheric moisture to near the average max for this time if
year. That means rain chances will be very high and the potential
for flash flooding is also above normal. So while it may seem
normal for heavy rainfall in the summer, this seems to be an
uptick above that but not to flash flood watch levels. 1 to 3
inches will be possible through tomorrow afternoon with a focus on
points further south in the CWA. The 80% pops for much of the CWA
may be on the conservative side and possible need overnight shift
to go with 100% as the ECMWF and HRRR suggest. The lower coverage
of QPF of the GFS is why didn`t go to 100 yet.

Model soundings show dry air moving in across all levels on Friday.
This reduction in precip water will result in lower coverage with
convection become more summer-like and diurnally driven. This should
also allow temperatures to moderate back up into the upper 80s.
Tstrm placement looks to shift further north as well with highest
pops along and north of I-12.

Model outputs for this weekend show the Bermuda ridge extending
across the GOM and northern Gulf coast with a northern stream trough
racing across the mid and upper Mississippi River Valley. This will
suppress afternoon convection quite a bit, bring down pops to around
30% Saturday and 10-20% on Sunday. Meanwhile, temperatures will
continue to moderate with highs in the upper 80s to lower 90s.

Going into next week, a piece of the Bermuda Ridge will break off in
the central GOM and try to remain there for a few days. This will
keep most of the CWA dry through Wednesday outside of a random storm
or 2. If anyone gets rain during this time, it will be areas in
SW/Coastal Mississippi or adjacent Louisiana Parishes.


Numerous showers and thunderstorms have develop across the area.
Although, convection typically dissipates with sunset, this isn`t
likely today. Showers and storms will persist overnight. Lower
ceilings will continue as well. MVFR conditions will prevail
overnight with periods of IFR conditions as storms move over
terminals and reduce visibilities with heavy rainfall.


Onshore flow has generally returned and will be in place through
the remainder of the forecast period. A slight compression in the
pressure gradient in the NWRN Gulf has spread into coastal waters
west of the Mississippi River. This will bring winds to right at
15 knots this evening and overnight. Therefore, will have exercise
caution headline in those zones. Winds will gradually weaken each
day there after as a surface ridge develops near the central Gulf.
Seas will mimic the winds and subside from 3 to 5 feet to 2 feet
or less from tonight to next week.



DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Monitoring Hydro

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  72  86  74  90 /  30  70  10  30
BTR  75  88  75  90 /  40  60  10  30
ASD  75  88  76  90 /  40  60  10  30
MSY  76  88  76  89 /  40  50  10  20
GPT  76  85  76  88 /  40  60  10  30
PQL  75  86  75  88 /  40  60  10  30



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