Scientific Forecaster Discussion
fxus64 klch 102114
Area forecast discussion
National Weather Service Lake Charles la
314 PM CST Tue Dec 10 2019
Short term [this evening through friday]
This afternoon's radar imagery shows showers extending from
southeast Texas northeastward into northern and central Louisiana
along a region of isentropic ascent behind the surface cold front.
This region of isentropic ascent is forecast to gradually shift
east-southeastward through this evening. The steadiest rainfall is
expected to continue through late this evening before gradually
ending after midnight as the best support for ascent progresses
east of the County Warning Area. Meanwhile, cold air advection will continue
through the overnight and contribute to temperatures falling into
the 30s/low 40s by sunrise.
High pressure will build into the region during the day Wednesday
and contribute to decreasing northeasterly winds. The high
pressure will result in clear skies which combined with insolation
which help counteract the continuing weak cold air advection and
result in temperatures climbing into the mid to upper 50s.
A weak shortwave trough is forecast to move across the lower
Mississippi River valley from Thursday into Friday. This will
support at least a slight chance for showers to develop, mainly
across southeastern Louisiana, from Thursday afternoon into
Friday. Otherwise, skies will be partly to mostly cloudy and
temperatures will climb into the 60s.
Long term [saturday through tuesday]
Longer range model guidance is in good agreement that
predominately northwesterly to westerly flow aloft will be in
place over the northern Gulf Coast from Saturday through late
Sunday. This will result in dry conditions and above normal
temperatures with highs in the upper 60s/low 70s during the
weekend. The next upper level trough is forecast to approach the
region on Monday and result in chances for showers and possibly
thunderstorms as well. The trough axis is expected to shift east
of the region on Tuesday and upper level subsidence combined with
surface high pressure building into the region should result in
dry conditions and cooler temperatures during the middle part of
Strong offshore winds of 20-30 knots with frequent gusts above
gale force will continue through the overnight hours over the
coastal waters. This offshore flow will result in below normal
water levels along the Inland Lakes and bays, particularly during
low tide Wednesday. P-etss guidance, which has been accurate thus
far throughout the event, has the lowest water levels only getting
down to -0.5 ft MLLW. Therefore, no low water advisories are
expected to be needed at this time.
Winds are expected to begin gradually decreasing near sunrise but
will remain above 20 knots across most of the coastal waters
through the day on Wednesday into Wednesday night. Therefore,
small craft advisories will be needed for the coastal waters
during the day tomorrow. However, in order to keep the messaging
in the marine hazard products simple, the current marine hazards
were left unchanged during this forecast package.
Winds and seas are expected to improve late Wednesday into
Thursday morning as the pressure gradient decreases over the
coastal waters. Fair navigating conditions and light winds will
persist into the weekend before the next low pressure system
approaches the coastal waters on Monday. Another period of strong
offshore flow is possible behind this system during the early to
middle part of next week.
Preliminary point temps/pops...
aex 32 56 33 58 / 80 0 0 10
lch 39 58 40 59 / 80 0 0 20
lft 42 58 41 60 / 80 10 10 30
bpt 40 58 41 59 / 40 0 0 10
la...Wind Advisory until 9 PM CST this evening for laz041>045-052>055-
Texas...Wind Advisory until 9 PM CST this evening for txz215-216.
GM...Gale Warning until 6 am CST Wednesday for gmz455-475.
Gale Warning until 6 am CST Wednesday for gmz450-452-470-472.
Small Craft Advisory until 6 am CST Wednesday for gmz430-432.
Small Craft Advisory until 6 am CST Wednesday for gmz435.