Flash Flood Warning 25, NWS Lake Charles, LA

Area Forecast Discussion
National Weather Service Lake Charles LA
1026 AM CDT Fri Aug 5 2022

.DISCUSSION...
Wx map shows high pressure ridge across the Northern Gulf of
Mexico, providing a south to southeast flow across the area.
Radar showing most of the showers and thunderstorms across the
coastal waters this morning, with showers now beginning to pop up
across Southwest Louisiana and Southeast Texas. Expecting the
showers and thunderstorms to pick up in areal coverage later this
afternoon. Made some adjustments to the chances of precipitation
this morning due to the later than expected start, but this
afternoon, will still see about 50-70% across the area. WPC
continues the marginal risk of excessive rainfall for Southeast
Texas and Southwest Louisiana today.

08/DML

&&

.AVIATION...
For the 08/05/2022 1800 UTC TAF package.

Expect scattered to numerous TSRA across SE TX/C and S LA this
afternoon. VCTS at all sites, with TEMPO groups for TSRA and MVFR
visibility/ceilings for BPT/LCH/LFT/ARA through 22z, and 20-24z
for AEX. Southeast winds around 8-10 kts expected this afternoon.

08/DML

&&

.PREV DISCUSSION... /issued 635 AM CDT Fri Aug 5 2022/

DISCUSSION...

For the 08/05/2022 1200 UTC TAF package.

AVIATION...

Very low clouds and patchy fog affecting the KAEX and KLFT
terminals to start off the period. IFR conditions will be possible
at these sites until about 05/14Z. Elsewhere, nocturnal shower
activity is affecting the KBPT terminal, and occasional shower
activity with MVFR/IFR conditions possible with the convection
through about 05/16Z.

A very moist airmass is in place, along with an upper level
weakness. This should allow for a good covering of showers and
storms later this morning into the afternoon, and affect all
terminals. Used radar trends and latest CAMs to try to time
activity at terminals. Away from the convection VFR conditions
will likely occur.

Rua

PREV DISCUSSION... /issued 428 AM CDT Fri Aug 5 2022/

SHORT TERM [Today through Sunday]...

Radar fairly active over the coastal waters this early morning as
an uptick in nocturnal showers can be attributed to a mid level
inverted trough/easterly wave feature located from south central
Louisiana into the northwest Gulf, and highly anomalous
(tropical-like) moisture associated with it.

The inverted trough/easterly wave will move westward across
southwest Louisiana and southeast Texas and adjacent coastal
waters today. Swath of precipitable water values above 2.25
inches, which is well above the 90th percentile level of SPC daily
climo,) will also move westward with this feature while the entire
forecast area will see PWAT values above 2 inches and above the
75th percentile level. So high rain chances can be expected
across the forecast area, especially in the afternoon, the best
chance and coverage will be over southwest Louisiana and southeast
Texas, and may occur at anytime during the day.

With PWAT values above the 90the percentile, mean RH from SFC-50H
over 80 percent, and enough instability with MU CAPE between 1500
and 2000 j/kg, storms with high rainfall rates will be possible
across lower southwest Louisiana and lower southeast Texas. 2 to 3
inch per hour rainfall rates with the stronger storms are not out
of the question. HREF probabilities show 15-20 percent chance of
greater than 3 inches in 1 hour and 25-30 percent chance of
greater than 3 inches in 3 hours for that area. Fortunately
antecedent conditions in this area can take some rainfall.

Still with the locally heavy rainfall possible, WPC has outlined
southeast Texas and southwest Louisiana in a Marginal Risk (level
1 out of 4) Potential for Excessive Rainfall leading to flooding.
At this point, street flooding in urban poor drainage areas looks
like the main hazard. The remainder of the forecast area will
also see some storms with torrential downpours, however just not
organized in nature.

The inverted trough will move off to the west for the weekend.
This will leave behind a deep southeast flow. So there will still
be ample Gulf moisture in place each afternoon, with PWAT ranging
from around the normal mean of 1.8 inches to near the 75th
percentile of 2 inches. So, expect scattered diurnal showers and
thunderstorms, and an active sea breeze each day, with the best
chance and coverage in the afternoon.

Rua

LONG TERM [Monday through Thursday]...

The region will remain embedded within broad upper level weakness
through much of the upcoming week while persistent deep tropical
moisture will continue to allow for scattered to widespread daily
afternoon convection. This activity will keep afternoon highs near
or slightly below climatological normals. As has been seen the last
couple of days, any of these storms will have the potential to
produce locally heavy rainfall that could lead to isolated flash
flooding.

Guidance continues to depict a weak frontal boundary reaching the
gulf coast by late next week with better consistency in timing and
structure. While the front is unlikely to bring anything resembling
colder air into the region, it may have the potential to turn winds
out of the north pulling in somewhat drier low level air by next
weekend. The official forecast will now reflect this in the day 7
timeframe. Guidance is also in surprisingly good agreement on the
long entrenched upper level ridge over the southwestern U.S. sliding
east and becoming centered over northeast Texas. This, combined with
the drier air in the wake of a frontal boundary would significantly
limit daytime convection and, ironically, increase afternoon highs
late in the period although overnight lows could be slightly cooler.
Significant shifts in the forecast at this timeframe are still
likely in the coming days.

Jones

MARINE...

Surface high pressure will remain east of Florida and ridge
across the northern Gulf of Mexico during this forecast period.
Therefore, the light to occasionally moderate onshore flow will
persist through the next several days.

An upper level disturbance moving across the northwest Gulf will
help provide numerous showers and thunderstorms today. Cloud to
water lightning and heavy rainfall greatly reducing visibilities
will be the main hazards with the storms.

This disturbance will move off to the west over the weekend with
more typical summertime convection expected for the coastal waters
over the weekend into early next week. That is a daily chance of
scattered showers and thunderstorms.

Rua

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.

&&

Hazardous Weather Outlook
National Weather Service Lake Charles LA
436 AM CDT Fri Aug 5 2022

LAZ041-073-074-TXZ201-215-216-261-262-061115-
Calcasieu-West Cameron-East Cameron-Hardin-Jefferson-Orange-
Southern Jasper-Southern Newton-
436 AM CDT Fri Aug 5 2022

This Hazardous Weather Outlook is for southwest Louisiana and
southeast Texas.

.DAY ONE...Today and tonight.

Scattered to numerous showers and thunderstorms are expected. Some
locally heavy rainfall may occur due to high rainfall rates between
1 and 3 inches per hour with the stronger storms. A Marginal Risk
(level 1 out of 4) Potential for Excessive Rainfall has been
outlined. If these rainfall amounts occur, flooding of low lying
areas and urban type street flooding will be possible. Also,
occasional to frequent cloud to ground lightning will occur with the
storms.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

There will be a daily chance for thunderstorms during the period.
Besides some locally torrential downpours, occasional cloud to ground
lightning can be expected.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

LAZ027>033-042>045-052>055-TXZ180-259-260-061115-
Vernon-Rapides-Avoyelles-Beauregard-Allen-Evangeline-St. Landry-
Jefferson Davis-Acadia-Lafayette-Upper St. Martin-Vermilion-Iberia-
St. Mary-Lower St. Martin-Tyler-Northern Jasper-Northern Newton-
436 AM CDT Fri Aug 5 2022

This Hazardous Weather Outlook is for central Louisiana, south
central Louisiana, southwest Louisiana, west central Louisiana and
southeast Texas.

.DAY ONE...Today and tonight.

There will be a chance for thunderstorms through the afternoon.
Occasional cloud to ground lightning and locally torrential downpours
can be expected with the storms.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

There will be a daily chance for thunderstorms during the period.
Besides some locally torrential downpours, occasional cloud to ground
lightning can be expected.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

GMZ430-432-435-450-452-455-470-472-475-061115-
Sabine Lake-Calcasieu Lake-Vermilion Bay-
Coastal waters from Cameron LA to High Island TX out 20 NM-
Coastal waters from Intracoastal City to Cameron LA out 20 NM-
Coastal waters from Lower Atchafalaya River to Intracoastal City LA
out 20 NM-
Coastal waters from Cameron LA to High Island TX from 20 to 60 NM-
Coastal waters from Intracoastal City to Cameron LA from 20 to 60 NM-
Coastal waters from Lower Atchafalaya River to Intracoastal City LA
from 20 to 60 NM-
436 AM CDT Fri Aug 5 2022

This Hazardous Weather Outlook is for the Gulf of Mexico and the
coastal lakes and bays of the Gulf of Mexico.

.DAY ONE...Today and tonight.

Scattered to numerous thunderstorms can be expected. Occasional to
frequent cloud to water lightning will be the main hazard. Also,
heavy rainfall will greatly reduce visibility

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Scattered thunderstorms can be expected for the weekend into early
next week. Locally higher winds and seas, torrential rainfall greatly
reducing visibility, and occasional cloud to water lightning will be
the main hazards.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.