Special Weather Statement, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
337 PM CDT Sun Jul 4 2021

.SHORT TERM (Tonight through Tuesday Night)...A broad upper level
low will be the primary driver of the short term forecast period.
In the low levels, a weak boundary over the area will dissipate
tonight and the pattern will be largely driven by the seabreeze
cycle with convection forming offshore in the late overnight and
early morning hours and then pushing inland with the seabreeze
front through the late morning and afternoon hours. The convection
should then dissipate in the early evening hours as daytime
heating and overall instability values wane.

In terms of the overall POP, the amount of atmospheric moisture
as measured by precipitable water values will be the main driver
of convective coverage. Lower precipitable water values of 1.5 to
2 inches today have limited overall convective development with
isolated to widely scattered convection occurring this afternoon.
This convection should quickly die off this evening, and
conditions look favorable for Independence Day festivities.
Precipitable water values should increase tomorrow with most
locations exceeding 2 inches by the afternoon hours. As a result,
convective coverage will be higher with POP values forecast in the
60 to 80 percent range. Storm motion will remain rather slow and
rainfall rates could be near 2 inches per hour, so some localized
street flooding issues could develop at times. The rain chances
will turn more scattered at 30 to 50 percent by Tuesday night as
instability values decrease with the loss of daytime heating. Similar
conditions are expected on Tuesday as precipitable water values
remain over 2 inches. Temperatures should be near average with
highs near 90 and lows in the 70s.

.LONG TERM (Wednesday through Saturday Night)...A similar pattern
as observed on Monday and Tuesday will continue through Wednesday
and Thursday as a broad and weak upper level trough axis lingers
across the Gulf South. A lack of strong low level synoptic
features will keep the convection driven by the seabreeze cycle,
and precipitable water values will remain in excess of 2 inches.
As a result, scattered to numerous showers and thunderstorms and
POP values of 50 to 70 percent are forecast each day. Storm motion
will remain limited, so localized flooding will continue to be
possible as rainfall rates could exceed of 2 inches per hour.

A broad and weak trough will linger over the area on Friday and
Saturday, but slightly drier air in the mid-levels may move in
from the south. This could reduce precipitable water values to
below 2 inches, and overall convective potential should decrease
to between 40 and 60 percent. The diurnal seabreeze cycle will
continue to drive the convective pattern with POP peaking in the
afternoon and dropping to a minimum over land areas during the
overnight hours. Temperatures will be little changed and near
average.

&&

.AVIATION...The 00z TAF should indicate the potential for another
period of low stratus and a mix of MVFR and IFR conditions at the
terminals between 10z and 14z tomorrow. Outside of this low
stratus event, prevailing VFR conditions are expected. However,
convection will once again be possible after 15z tomorrow. This
will be reflected with prevailing VCTS wording at the terminals
during the afternoon hours. PG

&&

.MARINE...A slight tightening of the pressure gradient over the
open Gulf waters tonight through tomorrow will likely keep winds
elevated at between 15 and 20 knots. The gradient should decrease
by Tuesday and a return to prevailing onshore flow of around 10
knots is expected for the remainder of the week. Although winds
will be calmer on Tuesday and Wednesday, a swell train emanating
from Tropical Storm Elsa in the far eastern Gulf could produce
higher seas of up to 6 feet and a longer period of up to 10
seconds during that time frame. Conditions should improve by
Thursday as the tropical system moves inland.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  71  90  72  86 /  10  60  50  80
BTR  73  90  74  87 /  20  70  60  90
ASD  74  88  74  87 /  20  80  70  80
MSY  75  87  75  87 /  30  80  70  90
GPT  75  86  74  85 /  30  70  70  80
PQL  73  87  73  87 /  20  70  70  80

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

PG

Special Weather Statement
National Weather Service New Orleans LA
543 PM CDT Sun Jul 4 2021

LAZ046-049-056-042315-
Iberville-Ascension-Assumption-
543 PM CDT Sun Jul 4 2021

...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN ASCENSION...
SOUTHEASTERN IBERVILLE AND NORTH CENTRAL ASSUMPTION PARISHES...

At 542 PM CDT, a strong thunderstorm was located near Belle Rose, or
7 miles southwest of Donaldsonville. The storm is moving slowly
northward.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Donaldsonville, St. Gabriel, White Castle, Paincourtville, Belle Rose
and Carville.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3003 9096 2995 9112 3014 9123 3024 9108
TIME...MOT...LOC 2242Z 149DEG 3KT 3005 9111

LN

Special Weather Statement
National Weather Service New Orleans LA
707 PM CDT Sun Jul 4 2021

MSZ070-071-050045-
Pike-Walthall-
707 PM CDT Sun Jul 4 2021

...A STRONG THUNDERSTORM WILL AFFECT WESTERN WALTHALL AND
SOUTHEASTERN PIKE COUNTIES...

At 707 PM CDT, a strong thunderstorm was located near Tylertown, or
11 miles southwest of Kokomo, moving northwest at 10 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Tylertown and Salem.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3118 9003 3117 9000 3114 9000 3113 8998
      3100 9003 3100 9032 3118 9032 3127 9004
TIME...MOT...LOC 0007Z 145DEG 7KT 3106 9010

KLG