Scientific Forecaster Discussion
fxus64 klix 180917
Area forecast discussion
National Weather Service New Orleans la
417 am CDT Wed Sep 18 2019
with a very slow forward pace by Imelda, there will almost be a
status quo in the fcast today. The moisture gradient still exists
along the miss river and a well established upper outflow from
Imelda will help sh/ts get lift once initiated today. A weak
convergent sfc flow still exists as well which helps with where
the convergent band will set up today. This is shown well in sfc
obs with southeast flow over the western Atchafalaya and east flow along
and east of the miss river. The initiating period will be after
the sun rises as it will take some heating to get things going,
but should be in roughly the same general places as they were
yesterday. Fortnately, areas over the western most portion of the
County Warning Area are getting some much needed rainfall while the remainder is
baking and dry. A backdoor front will move into the area Thursday
into Friday. Some sh/ts are being advertised with this front as it
moves through during the day Thursday. Supression ahead of this
front will couple with the supression on the outer periphery of
old Imelda to cause a very strong supression inversion which could
produce some strong heating. If enough heating can be achieved
Thursday, there could be a few strong or severe thunderstorms
along the front when it comes in and weakens the inversion. The
other possibility is that the inversion is able to bridge the
front keeping any thunderstorm from getting out of hand. But this
will need to be looked at later today into the overnight. There is
some dry air with this front but don't see any cool air. But when
some of this dry air filters into the eastern most portion of the
area, evenings and mornings should feel a little more comfortable
Friday into the weekend. Models disagree on how long the dry air
will stay and am more inclined to follow the GFS on this bringing
moisture back to the area once the Imelda remnants have departed.
Expect VFR conditions for all area terminals through the early
morning hours today. A few bands of tropical showers and storms may
press east enough across the Atchafalaya basin to reach near kbtr and
khum terminals, but will be more isolated in coverage. However, any
one band/stronger storm may contain gusty erratic downdraft winds
and locally heavy rainfall leading to periodic lower flight
categories in this region. Otherwise, VFR conditions can be expected
elsewhere through the taf period. Klg
winds will remain rather weak until Thursday when a back door
front will move into the coastal waters causing easterly winds to
rise to around 20kt through the weekend. By the early part of
next week, high pressure settles back into the area and winds
again go light.
dss code: green.
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; marginal risk severe or excessive rain.
Yellow = heightened impacts with short-fused watch, warning or
advisory issuances; radar support for slight risk severe
or excessive rain.
Orange = high impacts; enhanced risk severe; nearby tropical events;
hazmat or other large episodes.
Red = full engagement for moderate to high risk of severe and/or
excessive rainfall, or direct tropical threats; events of
Preliminary point temps/pops...
mcb 94 72 91 70 / 20 10 50 20
btr 91 73 90 73 / 60 10 40 20
asd 94 73 91 72 / 10 10 50 20
msy 92 77 91 77 / 40 10 40 20
gpt 92 74 89 72 / 10 0 50 30
pql 97 73 90 70 / 10 10 50 20