Areal Flood Warning 3, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
453 PM CDT Fri May 21 2021

.SHORT TERM (Tonight through Monday)...

At long last the drier weather is finally developing and moving
into our area from east to west as high pressure builds in. A well
defined low pressure system over the western Gulf of Mexico has a
medium chance of becoming a short-lived tropical depression or
storm as it moves northwest before it moves inland over the
northwest Gulf coast region tonight. The far eastern rain bands
between this low and the high pressure to the east should mostly
remain in southwest to south central Louisiana, west of the
forecast area.

The main concerns that will linger into the weekend and beyond is
coastal flooding and river flooding. The combination of tide
gages trends, ground truth reports, probabilistic extra-tropical
storm surge data, river forecasts and onshore winds through
Saturday all point to a continued slow increase in water levels
for some inland tidal basin areas, especially on the north and
west sides of Lakes Pontchartrain and Maurepas. Have expanded the
Coastal Flood Warning again to add Ascension Parish (mainly for
eastern tidal basin area closest to Lake Maurepas) and St. James
Parish. All areas in the warning are in effect until 4 pm
Saturday, and some areas may need to eventually need to be
extended even later. Remaining areas in the Coastal Flood Advisory
expire later tonight, but some areas may need to be extended into
Saturday. The Comite and Amite River basin are the main river
systems of concern that have mostly minor flooding, although
almost moderate for the current crest at Comite Joor Road in Baton
Rouge and moderate at Hwy 22 near Maurepas.

High pressure will continue to build in over the weekend into
early next week with no rain in the forecast and mostly clear to
partly cloudy skies. This will almost act and feel like a "back-
door cold front" even though it will get warmer because drier air
will also be felt at the surface with dewpoint temperatures
dropping into the low 60s to around 60 for some areas at times
over the weekend and Monday. It won't be as windy, but will
remain a bit breezy on Saturday with east-southeast winds 15 to 20
mph expected. Winds will finally ease back to around 10 mph or
less on Sunday into Monday which will help with ceasing the rising
tidal water.

.LONG TERM (Tuesday through Friday)...

High pressure is expected to mostly be in control of the weather
in our region. The exception will be a shortwave trough that will
move out of the southern Plains across the lower Mississippi
Valley Tuesday night and Wednesday morning. Most of the rain will
remain west and north of the forecast area. It will be a generally
much needed dry period with temperatures more typical of late May
with highs in the mid 80s to near 90 and lows in the mid to upper
60s.

&&

.AVIATION...

Mostly VFR conditions with a few lower MVFR CIGS will trend
towards mostly VFR as the evening progresses. Drier conditions
moving in from the east will decrease cloud cover tonight and VFR
should prevail tonight into Saturday. The strong and gusty
east/southeast winds will persist this afternoon, drop off
tonight, then pick up again on Saturday but not as much as today.

&&

.MARINE...

Continued strong pressure gradient between high pressure to the
east and low pressure over the western Gulf of Mexico will
maintain strong east-southeast winds across the marine area
tonight into Saturday, although trending down towards the lower
end of Small Craft Advisory later tonight into Saturday. The long
fetch will continue to keep seas of 6 to 10 feet tonight that
should drop to below 7 feet late Saturday night. Small Craft
Advisories have been extended accordingly. Improvement will then
occur Sunday and beyond as high pressure builds over or near the
central Gulf coast and winds drop off mostly to 10 knots or less.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  65  86  62  86 /   0   0   0   0
BTR  67  85  63  85 /   0   0   0   0
ASD  68  84  63  86 /   0   0   0   0
MSY  72  84  68  85 /   0   0   0   0
GPT  69  82  65  85 /   0   0   0   0
PQL  67  82  63  85 /   0   0   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Wind Advisory until 7 PM CDT this evening for LAZ058>061-063>070-
     072-075>078.

     Coastal Flood Advisory until 4 AM CDT Saturday for LAZ060-061-
     066>068-077.

     Coastal Flood Warning until 4 PM CDT Saturday for LAZ049-050-057-
     058-064-069-070-072-075-076-078.

GM...Small Craft Advisory until 4 AM CDT Sunday for GMZ550-552-555-
     557-570-572-575-577.

     Small Craft Advisory until 4 AM CDT Saturday for GMZ530-532-534-
     536-538.

MS...Wind Advisory until 7 PM CDT this evening for MSZ080>082.

     Coastal Flood Advisory until 4 AM CDT Saturday for MSZ081-082.

     Coastal Flood Warning until 4 PM CDT Saturday for MSZ080.

GM...Small Craft Advisory until 4 AM CDT Sunday for GMZ552-555-557-
     570-572-575-577.

     Small Craft Advisory until 4 AM CDT Saturday for GMZ532-534-536-
     538.

&&

22/TD