Areal Flood Warning 8, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
809 AM CDT Mon Aug 30 2021

.AVIATION...

Low ceilings and numerous showers and possibly embedded storms
will continue across most of the TAFs this morning as Tropical
Cyclone Ida continues to slowly pull away to the north. MVFR
prevails and expect IFR to continue at times especially around
KMCB to KASD and KGPT. Lower rain chances expected in the
afternoon but still looks like scattered to numerous showers and
possible storms. Lowest chances expected around KBTR and KHUM.
Trailing bands of showers appear tonight but should shift off to
the east overnight. Winds will trend to south and southwest
during the day while gradually decreasing.

PREV DISCUSSION... /issued by National Weather Service Jacksonville
FL/

LONG TERM (Wednesday through Saturday)...

The convergence boundary and resultant showers and thunderstorms
will continue to develop over the area on Wednesday and keep likely
POP values in place through the day. By Thursday, deep layer
northerly flow will take hold of the region and this will usher in a
much drier and much more stable airmass. Precipitable water
values will decrease to between 1.5 and 2 inches, and rain chances
will diminish to 20 percent or less from Thursday through
Saturday as strong upper level subsidence warms the mid-levels and
reduces instability. Some weak cool air advection will also
occur, and this should help with recovery and restoration efforts.
Temperatures are projected to dip into the 60s and lower 70s at
night and highs are only expected to rise into the upper 80s.
Humidity values will also be a bit lower than normal for early
September.

MARINE...Hazardous conditions for maritime interests continue
today as what is now Tropical Storm Ida moves inland across
Mississippi. Winds will start to ease today, but a tight pressure
gradient over the coastal waters will keep winds in the Small
Craft Advisory range (20-30 kts) through tonight. The pressure
gradient should continue to weaken on Tuesday and Wednesday as
winds should decrease to 10 to 15 knots by Wednesday night. Seas
will correspondingly decrease to 3 to 5 feet by this time. A weak
front will slip through on Thursday and winds will shift to the
north at 5 to 10 knots for the end of the week. Seas of 2 feet or
less are expected with these lighter winds.

HYDROLOGY...Surge will slowly pull back through today along
the coastal and river parishes today. However, coastal flooding will
likely continue. Moderate to Major river flooding is expected to
begin today or tonight a last through at least Wednesday on
Natalbany, Tchefuncte, Tangipahoa, Bougue Falaya Rivers. Creeks and
tributaries of the Pearl River are also expected to reach moderate
to major flood stages as well over the next 12 to 24 hours if they
haven't already.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  79  72  89  72 / 100  60  40  20
BTR  82  72  89  74 /  80  60  40  40
ASD  86  75  90  75 /  90  80  60  40
MSY  89  77  92  78 /  70  60  60  50
GPT  84  76  89  75 / 100  70  60  50
PQL  83  75  88  73 / 100  80  70  50

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Tropical Storm Warning for LAZ035>037-039-048-050-058-060-061-
     063-064-068>072-075>078.

     Flash Flood Watch through late tonight for LAZ037-039-049-050-
     057>061-063>072-075>078.

     Coastal Flood Advisory until 9 PM CDT this evening for LAZ056-
     059-065>067.

     Storm Surge Warning for LAZ049-050-057-058-060-061-063-064-
     068>070-072-075-076-078.

GM...Tropical Storm Warning for GMZ530-532-534-536-538-552-555-557-
     572-575-577.

     Small Craft Advisory until 5 AM CDT Tuesday for GMZ550-570.

MS...Tropical Storm Warning for MSZ068>071-077-080>082.

     Flash Flood Watch through late tonight for MSZ069>071-077-
     080>082.

     Storm Surge Warning for MSZ080>082.

GM...Tropical Storm Warning for GMZ532-534-536-538-552-555-557-572-
     575-577.

     Small Craft Advisory until 5 AM CDT Tuesday for GMZ570.

&&