Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
FXUS64 KLIX 271303
Area Forecast Discussion
National Weather Service New Orleans LA
803 AM CDT SAT AUG 27 2016
Moisture is back up in the sounding this morning with PW above
average at 2.2 inches. Heavy rain is possible with some of the
storms again today but that should mainly be confined to the
southernmost LA coast and offshore waters. However HRRR runs this
morning indicate a band of storms coming just a bit further inland
today... up to the I 10/12 corridor. There is plenty of
instability above an inversion in the first 1200 feet with mixed
layer CAPE at 1500 J/KG. Winds are easterly to 500 mb then become
more southerly above.
.PREV DISCUSSION... /issued 450 AM CDT SAT AUG 27 2016/
Moisture levels expected to be on the return as a trough of low
pressure to the south of the Louisiana coast this morning moves
slowly westward across the Gulf of Mexico. At this time, the
National Hurricane Center gives this area just a 10 percent chance
of developing into a tropical system. Regardless, this system will
be responsible for increasing our rain chances over the weekend
and could cause some heavy rainfall across the extreme southern
parts of our area. Thankfully, these areas did not see anywhere
near the amounts of rain that points further north did last week
in the previous event. Temperatures over the weekend will be
generally in the upper 80s to lower 90s depending mainly on where
the shower and thunderstorm activity develops, which is more
likely the further south towards the coast one is.
Let`s start with what is most likely to occur at this point before
getting on to the thing that is most likely to be the reason you
are reading this.
No significant changes made to the previous forecast. Once the
aforementioned system south of the Louisiana coast moves to the
west, high pressure will build in across the region and remain in
place for most of the rest of the work week. This will lower
precipitation chances to 20 percent or less across the area and in
turn cause temperatures to rise into the mid 90s in most places.
With the increase in temperatures and the lack of convection in
the area, heat advisories may be needed later in the week.
As far as the Invest currently known as 99L is concerned, the
National Hurricane Center has lowered the chances of development
to 20 percent in the next 48 hours and 40 percent over the next
five days. As they mention in the latest tropical weather outlook,
upper level winds continue to be a deterrent to the system
developing and are likely to remain that way for most of the
weekend until what is left nears Florida. Both the ECMWF and the
GFS are just having all sorts of fits with this system and are
hard to put any stock in at this point with the latest runs pretty
much losing the system all together. Overall the current 06Z early
and late cycle models still point towards the Gulf of Mexico and
looking at the overall pattern, there is nothing to really argue
there. Some convection is trying to fire near the assumed center
as it has the previous few nights but overall the organization of
the system is somewhere in the terrible to horrible range.
Therefore, the question is, will there be anything to speak of
when it gets to that point. The bottom line, as it has been for
days now, is to remember that it is late August and the
climatological peak of the hurricane season is a mere two weeks
away. Stay weather aware!
VFR conditions are forecast to generally prevail at most terminals
through the TAF forecast period outside areas of convection. The
convection will be most prevalent during the afternoon hours and
more likely to affect coastal TAF sites. Therefore, KHUM, KMSY and
KNEW are the terminals most likely to be impacted by showers and
thunderstorms today. The convection will begin to wane somewhat
after sunset, especially across the more inland areas.
A persistent easterly wind of 10 to 15 knots is expected to remain
in place through Tuesday on the southern periphery of a high
pressure system over the Tennessee Valley. This easterly flow should
keep tides slightly elevated with tide levels running around a foot
above normal through Tuesday. Seas will generally range from 1 to 4
feet. Winds will become more variable by mid week.
DSS code: Blue
Activities: Flood recovery support
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.
.PRELIMINARY POINT TEMPS/POPS...
MCB 91 73 90 73 / 20 20 40 30
BTR 90 74 89 74 / 50 40 60 40
ASD 89 77 88 77 / 50 40 60 40
MSY 86 78 88 79 / 60 50 70 50
GPT 88 78 89 78 / 40 30 60 40
PQL 88 77 89 77 / 30 30 60 40