Scientific Forecaster Discussion
fxus64 klix 200842
Area forecast discussion
National Weather Service New Orleans la
342 am CDT Sat Jul 20 2019
precipitable water values will approach 2" today and stay within a range of 1.8 to
2.2" for the next several days. This subsequently causes
convective temps to fall to and below Gulf water temps. And Viola,
nocturnals thrive once the inversion if destroyed from below. This
same scenario will play out during the daylight hours but will be
mainly over land areas where the inversion will also be destroyed
from underneath as the land heats up. And with convective temps so
low, it won't take long to get things going. This is all thanks to
an upper to mid level maritime anticyclone over the area. The
environment also becomes conducive for waterspout development as
well. The best time that these would occur would be between about
4am to late morning to around noon. This is the time frame that
the very warm waters cause the greatest instability. This scenario
should play itself out day after day. A cold front looks to move
in on the action by Tuesday. This will provide an even better
focus and increased lift giving rise to even higher rain chances.
The front stalls somewhere along the Gulf Coast and where this
occurs, some periods of heavy rain could occur. Model trends
should eventually give this scenario more credence as we get
closer to that time period.
Aviation...outside of the threat for scattered thunderstorms today,
the forecast calls for prevailing VFR conditions at all of the
terminals. Thunderstorms in the vicinity wording is included at all of the terminals for the
afternoon hours when the atmosphere is most unstable. By 00z, any
lingering convection should be dissipating. If a thunderstorm
directly impacts a terminal, an hour or less of gusty winds,
lightning strikes, and reduced visibilities due to rainfall can be
Marine...little change in the marine forecast. A broad surface
high will continue to extend across the eastern Gulf of Mexico
through Sunday. South-southeast winds of 5 to 10 knots and seas of
2 feet or less are expected. There will be an upper level inverted
trough axis sliding through the region, and this will result in a
higher than average risk of convection. Thunderstorms will be most
prevalent in the overnight and early morning hours when a diurnal
maximum occurs over the warm Gulf waters. Gusty winds and
waterspouts will be the main concern from any thunderstorms that
form. The high will become more centered over the waters on Monday
with light and variable winds expected. A slightly lower risk of
thunderstorms is also anticipated as the upper level trough weakens.
A front is then expected to move into the coastal waters on Tuesday
and become stalled over the waters on Wednesday and Thursday. Winds
will remain variable as the front meanders over the waters, and will
also remain fairly light at 10 knots or less. Seas will also remain
fairly calm at 2 feet or less through the middle of next week. A
risk of stronger thunderstorms will also accompany the front with
strong winds and frequent lightning strikes the main concern. Pg
dss code: blue.
Activities: flood warnings continue along the Mississippi River.
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
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 rain; direct tropical threats; events of National
Preliminary point temps/pops...
mcb 89 72 89 72 / 50 20 60 10
btr 90 74 88 73 / 60 20 80 10
asd 90 74 89 73 / 60 20 60 20
msy 90 77 89 76 / 60 30 70 20
gpt 87 75 88 75 / 60 30 60 20
pql 90 74 91 73 / 60 30 60 10