LIX issues Area Forecast Discussion (AFD) at Jan 20, 5:36 AM CST ...NEW AVIATION...002
FXUS64 KLIX 201136 AAA
AFDLIX
Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
536 AM CST Mon Jan 20 2025
...NEW AVIATION...
.SHORT TERM...
(Today through Tuesday Night)
Issued at 349 AM CST Mon Jan 20 2025
...A RARE DISRUPTIVE WINTER STORM AND DANGEROUSLY COLD WIND
CHILLS BECOMING INCREASINGLY LIKELY...
A strong arctic high pressure will slide southward from the
Cornbelt through the day and into overnight tonight. This will
continue to push colder and drier air into the region from the
north. Aloft, it's actually quite remarkable as the broad scale
trough axis (not to mention the H5 499dam low north of Lake
Superior) encompasses nearly all of the lower 48 this morning.
Needless to say we aren't the only folks cold this morning. As the
high moves southward, a coastal trough begins to develop just
east of the lower Texas Gulf Coast as a positively tiled upper
level shortwave amplifies over the high plains. Models have this
feature closing off and moving generally eastward over the central
Gulf of Mexico. As the surface low deepens, low level moisture
begins to increase across the northwest and eventually the central
Gulf States. As this occurs, the highly advertised event should
begin to unfold.
So, when using the term highly advertised it is assumed most have
been following the forecast. So, has anything changed since the
afternoon package on the 19th? Somewhat, models are a tad further
south with the main precip shield. This is likely indicating that
the dense arctic airmass is settling in a bit stronger (or
colder). This will do two things. 1) slightly more efficient
liquid/snow ratios with the cooler airmass and 2) a reposition of
the band of heaviest snow. Of course number 2 is still yet to be
determined naturally given the mesoscale influence. However, the
mesoscale models are a bit bullish outside of the 3km NAM, which
is drier and way further south. That said, with the adjustment
within globals and supporting mesoscale models, the gradient in
snowfall amounts will be tight the further north you go despite
the more efficient liquid/snow ratios.
That said, focusing on the model guidance, overall the GFS leans a
tad on the drier side when compared to many mesoscale models and
ECM. Following the consensus for now and adjusted snowfall totals
upward to account for the latest upward trends across the
board...except for the southwest MS Counties were believe it or
not moisture will likely be suppressed by the dry air quickly
rushing southward on the backside of this system. That said, the
current totals are an average. A frontogenetic band of heavier
snow is possible, but once again this will be very difficult to
pin down in advance so there is still a bit of uncertainty and
adjustments are still likely. Regardless, there is confidence that
the CWFA will likely experience not only a rare but disruptive
winter storm Tuesday.
We're not quite done yet. Let's talk precip types. Although the
more dense and colder air does move southward, there still could
be some mixed precip at onset, especially coastal sections of
Louisiana. Also, on the backside with loss of moisture down column
there could be some light freezing drizzle or rain on the
backside. Because the southern trend, we did decide to expand the
winter storm warning for all of the forecast area. As for
temperatures? Continued the cold weather advisories through the
next couple of days. Kept the Excessive Cold Watch in place...but
in subsequent packages, this too will likely be upgraded. (Frye)
&&
.LONG TERM...
(Wednesday through Sunday)
Issued at 349 AM CST Mon Jan 20 2025
By Wednesday the Gulf of Mexico system will have exited stage east
leaving us with decreasing cloudiness. Aloft, dry northwest flow
will continue so temperatures will still remain much below climo.
In fact, the day very well may start with the need for an extreme
cold warning as wind chill values could be as low as the single
digits with locations along and north of the I10/12 corridor in
the teens (actual air temp). However, temperatures will begin to
gradually increase going later into the long term
period...although they will still lean below average. Surface
high pressure going into the weekend will move over the region and
spread east allowing for a warm return flow to finally help bring
us out of the icebox. The return flow and height rises thanks to
a developing ridge over the western Caribbean will help bring us
back to near average, at least for high temps. That said, with
high pressure in control and dry northwest flow through a majority
of the long term, no additional precip chances through the long
term period. (Frye)
&&
.AVIATION...
(12Z TAFS)
Issued at 535 AM CST Mon Jan 20 2025
VFR conditions will last through today with light to moderate
northerly winds. Eventually, high clouds will overspread the
region with time and CIGs will begin to lower toward the end of
the 24 hour cycle. Northerly or northeasterly winds will increase
by the end of the cycle as well. For MSY, added -SHSN and PROB -SN
and added a couple hours for BTR as snow showers begin to develop.
By the end of the 30 hour MSY cycle, expect precip to gradually
increase bringing down CIGs and VIS respectively. (Frye)
&&
.MARINE...
Issued at 349 AM CST Mon Jan 20 2025
Marine conditions will continue to decline over the next day or
two as a low develops over the Gulf with gales expected for
portions of the Gulf of Mexico for Tuesday. Otherwise, hazardous
marine conditions will remain possible through early Wednesday
before improving later in the day. From this point forward, mostly
light to moderate winds and seas can be expected. (Frye)
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 39 22 31 13 / 0 20 80 10
BTR 45 27 33 16 / 0 30 90 10
ASD 44 26 34 18 / 0 10 90 20
MSY 42 29 34 25 / 0 10 90 20
GPT 43 26 34 18 / 0 10 90 30
PQL 46 25 35 19 / 0 10 80 40
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Cold Weather Advisory until 9 AM CST this morning for LAZ034>037-
039-046>048-056>060-064>071-076>090.
Cold Weather Advisory from 6 PM this evening to 6 PM CST Tuesday
for LAZ034>037-039-046>048-056>060-064>071-076>090.
Winter Storm Warning from midnight tonight to midnight CST
Tuesday night for LAZ034>037-039-046>048-056>060-064>071-
076>090.
Extreme Cold Watch from Tuesday evening through Wednesday
morning for LAZ034>037-039-046>048-056>060-064>071-076>090.
GM...Small Craft Advisory until midnight CST Tuesday night for GMZ530-
532-534-536-538-557.
Small Craft Advisory until 6 AM CST Tuesday for GMZ550-552-555-
570-572-575-577.
Gale Warning from 6 AM Tuesday to midnight CST Tuesday night for
GMZ550-552-555-570-572-575-577.
MS...Cold Weather Advisory until 9 AM CST this morning for MSZ068>071-
077-083>088.
Cold Weather Advisory from 6 PM this evening to 6 PM CST Tuesday
for MSZ068>071-077-083>088.
Winter Storm Warning from midnight tonight to midnight CST
Tuesday night for MSZ068>071-077-083>088.
Extreme Cold Watch from Tuesday evening through Wednesday
morning for MSZ068>071-077-083>088.
GM...Small Craft Advisory until midnight CST Tuesday night for GMZ532-
534-536-538-557.
Small Craft Advisory until 6 AM CST Tuesday for GMZ552-555-570-
572-575-577.
Gale Warning from 6 AM Tuesday to midnight CST Tuesday night for
GMZ552-555-570-572-575-577.
&&
$$
SHORT TERM...RDF
LONG TERM....RDF
AVIATION...RDF
MARINE...RDF
Source:
LIX issues Area Forecast Discussion (AFD) at Jan 20, 5:36 AM CST ...NEW AVIATION...---------------
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