Gretna, Louisianna 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

962
FXUS64 KLIX 180339
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
939 PM CST Fri Jan 17 2025

...New UPDATE...

.UPDATE...
Issued at 935 PM CST Fri Jan 17 2025

Shortwave trough and associated surface low and front from
Oklahoma to west Texas will race into the Ohio River Valley over
the next 24 hours. With the system moving to the northeast, that
will make for a somewhat gradual frontal passage on Saturday, with
any significant cooling/drying not occurring until late in the day
or overnight. Any rainfall to this point has been very light,
less than one-tenth of an inch. Considering how dry the LIX 00z
sounding was between 650 and 800 mb, this isn`t too surprising.

Temperatures that had fallen off a bit from daytime highs in the
60s toward sunset have actually rebounded a few degrees in the
last hour or two. Wind speeds have increased as well, as the
pressure gradient tightens a bit. Expect very little, if any,
temperature dropoff the remainder of the night. We`ll update
hourly temperature/dew point/wind grids if they slip out of
tolerance a bit, but the updated ZFP recently sent is likely to be
the only update this evening. The forecast beyond sunrise Saturday
is unchanged.

&&

.SHORT TERM...
(This evening through Saturday night)
Issued at 405 PM CST Fri Jan 17 2025

As expected, the cloud cover has returned to the area ahead of our
next system that will bring our rain chances later tonight into
Saturday. Low pressure is developing over the central plains right
now and is expected to shoot eastward into Saturday. With this low
pressure system comes a frontal boundary and out ahead of the front
moisture will be surging back in from the Gulf which increases PoPs
late tonight. Rain will be fairly light, but some embedded
thunderstorms can`t be ruled out given a little bit of instability
is available. We dry out by late Saturday with the front arriving
sometime in the evening Saturday.

In terms of temperatures, Saturday will actually be quite warm with
high temperatures well above seasonal normals into the low to mid
70s for most of the area. Enjoy this warmth while you can because it
will be the last "warmth" you will likely see for the majority of
the next week or so. Saturday night temperatures will already be
down into the 30s for most northern areas and the low 40s for
southern areas.

Our arctic front will be hot on the heels of the first front,
quickly following it and moving through sometime overnight Saturday
into Sunday morning. This front will rush in bitterly cold and dry
air into the area.

&&

.LONG TERM...
(Sunday through Thursday night)
Issued at 405 PM CST Fri Jan 17 2025

Onto the impactful part of the forecast, our arctic airmass and
potential winter weather. First, we are confident in the bitterly
cold that is coming starting Sunday night. Overnight lows Sunday, or
Monday morning lows, will likely be around or below 25 degrees for
areas north of the lake and including the MS coast. Areas up in
Southwest MS may even dip below 20 degrees. The southshore will see
slightly warmer conditions, but not by much with forecasted lows in
the upper 20s. Wind chill values will be in the teens to low 20s for
northern areas, possibly dipping into the single digits for SW MS,
and the low to mid 20s for southern areas. Monday night, or Tuesday
morning, lows will be very similar to the previous night with the
low to mid 20s for northern areas and the upper 20s for southern
areas. Similar wind chills are expected Tuesday morning and
Wednesday morning. These temperatures are a concern for pipes
bursting. Knowing this, Cold Weather Advisories are almost certain
to be issued and Extreme Cold Warnings are on the table.

Now onto the precipitation. A low pressure system will form over the
Gulf of Mexico on Monday and make its way northward before turning
east. We have seen quite a bit of model consensus over the last 12
hours. The last couple runs of both the GFS and Euro models have
shown more of an all snow, or mostly snow, solution. If you remember
yesterday we had about 3 scenarios that could play out and while the
other scenarios aren`t out of the question, snow probabilities have
been increasing. There is still a risk of a snow to freezing rain or
sleet transition for southern areas, which would bring major
impacts. Areas along the coast would be the most likely to see any
freezing rain or sleet. Probabilities of 1 inch of snow or greater
are around 40-50% for nearly the entire area and for 4 days out
those probabilities are rather high. Currently the most likely snow
accumulation is somewhere in the 1-3" range, with highest totals to
the NW. Winter Storm Watch/Warning criteria for our area is an inch
or greater, so that will be something that would need to be looked
into later in the weekend and on Monday.

Most areas will already have been very cold well in advance of the
precipitation if it falls, so knowing that if we do see
precipitation fall it is very likely to stick to roads right away.
Another big concern is the possibility of precipitation melting and
then refreezing on Wednesday/Thursday IF the existing precipitation
has not completely melted. Hazardous driving conditions are likely
on Tuesday and could linger into Wednesday and Thursday if we see
the refreezing become an issue.

A lot of model differences still with the possible next system late
in the week, the GFS has actually completely taken it out. Given
this and that we have impacts earlier int eh forecast, won`t really
get into this system just yet.

&&

.AVIATION...
(00Z TAFS)
Issued at 530 PM CST Fri Jan 17 2025

Most terminals were VFR at forecast issuance, although most had
cloud bases in the FL025-035 range. Expect most terminals to
bounce back and forth during the evening hours before settling
into the MVFR range more solidly after 06z. Area of rain to our
west has been diminishing over the last few hours, but expect at
least some to arrive during the late overnight hours. Cannot rule
out a few elevated rumbles of thunder, but confidence is not high
enough to pinpoint a threat window. Should see some improvement in
ceilings by midday Saturday. Winds may start to become an issue
downwind of Lake Pontchartrain at the New Orleans terminals beyond
06z Sunday.

&&

.MARINE...
Issued at 405 PM CST Fri Jan 17 2025

Winds currently out of the SE will gradually turn more southerly
this evening and eventually SW overnight into Saturday. While
shifting we will also see winds increase, up to Small Craft Advisory
criteria which is in place beginning at 09z tonight. These enhanced
SW winds will very briefly come down Saturday afternoon and evening
before ramping back up ahead of our next system. NW winds will rise
to ~25kts Sunday into Monday as an arctic air mass dives down into
the area. A surface low pressure system will develop on Monday and
make its way north, which will bring northerly winds possibly up to
gale force. In addition to the winds, a cold rain and possibly
wintry mix of precipitation will also come with the low.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  52  70  32  42 /  60  10   0   0
BTR  57  74  37  47 /  30  10   0   0
ASD  56  72  38  49 /  50  30  10   0
MSY  58  71  41  48 /  30  40  10   0
GPT  55  68  39  49 /  70  40  10   0
PQL  56  71  40  51 /  80  40  20   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 9 AM CST Saturday for GMZ550-552-555-
     557-570-572-575-577.

MS...None.
GM...Small Craft Advisory until 9 AM CST Saturday for GMZ552-555-557-
     570-572-575-577.

&&

$$

SHORT TERM...HL
LONG TERM....HL
AVIATION/UPDATE...RW
MARINE...HL