LIX issues Area Forecast Discussion (AFD) at Jan 5, 5:37 PM CST ...New AVIATION...061
FXUS64 KLIX 052337
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
537 PM CST Sun Jan 5 2025
...New AVIATION...
.SHORT TERM...
(This evening through Monday night)
Issued at 218 PM CST Sun Jan 5 2025
Much to discuss in the short term today. First, eyes are on the
potential for severe weather. Indeed, our northwest tier is under
a tornado watch through 06/03z. This is where the best
instability and lift will be. Points east, looking at a special
20z sounding wind shear and CAPE are overachieving a bit. Lapse
rates are steep with very little in the way of CIN to limit
convection. So much so that showers have developed over the last
couple of hours within the warm sector. This will help stabilize
a bit and without much forcing yet, the showers aren't growing
very tall...generally at most 20kft. Despite this, the shear is
still just enough to allow these narrow and weak updrafts to
rotate, so we'll have to monitor this at least over the next few
hours.
As sunset takes place the shear increases. The current 40kt LLJ at
925mb will grow a bit stronger as the system nears overnight. SRH
will enhance. However, as the weaker broad scale forcing moves
in, instability will have decreased. The strong shear will likely
roll individual updrafts limiting the potential at least out ahead
of the line. Now, the synoptically forced line of storm will
begin to move into our western tier around 6pm give or take. As
mentioned shear and forcing are there but instability will crash.
Overall, weakening of the line is expected as the forcing begins
to leave the region orphaning the convective line as it travels
eastward through midnight and beyond. In terms of severe...overall
message remains locked and no real changes from previous forecast
packages.
Now to talk about the cold. Not too much to say other than behind
the front winds remain strong, shift to the northwest, and usher
in some well below average temperatures for the rest of the short
term period. With strong CAA and weighing on mesoscale models
with better low level coordinates, decided to blend Monday's temps
a bit taking out the global warm bias. That said, forecast now
indicates very few get out of the 30s tomorrow afternoon, again
just due to low sun angle some early cloudiness and such a strong
cold air advection regime. Temperatures crash on Monday night and
another cold weather advisory is looking likely. The good news,
if there is good news, winds will remain elevated meaning
radiational cooling will not be maximized....so it could be worse
or at least colder. (Frye)
&&
.LONG TERM...
(Tuesday through Saturday night)
Issued at 218 PM CST Sun Jan 5 2025
Much below average temperatures will continue into the long term
period. The upper level pattern becomes zonal or progressive in
nature. Although this usually allows for some moderation in
temperatures, heights/thicknesses remain very low, which should
keep us from warming. By mid to late week eyes shift to the
northwest as strong H5 short wave begins to amplify over the
Rockies on Thursday and Friday. This will initiate a coastal trough
east of the lower Texas Coast allowing for surface cyclogenesis
to occur over the Gulf. The Gulf low is forecast to move over our
CWFA sometime during the day Friday. Although wintry weather
doesn't look likely in this low track, some initial precip may
have a few ice pellets etc given wet bulbing in a very dry
boundary layer. But this will lead to nothing more than
conversation in terms of impacts.
As the low moves through, some pretty high QPF values have been
recognized in the globals. Given the hydro vulnerable southshore
will be in the warm sector with plenty of moisture, there could
be a localized hydro threat for the southshore areas, at least in
urbanized and poor drainage areas. Otherwise, temperatures do
tick upward Thursday and Friday with weak WAA, and behind the
system roughly about the same with no huge cool down and no huge
warm up...but largely still below average for this time of year.
(Frye)
&&
.AVIATION...
(00Z TAFS)
Issued at 530 PM CST Sun Jan 5 2025
A line of convection will pass over the terminals this evening in
advance of a very strong cold front. Winds will also remain gusty
in advance of this line of convection from the south and some low
level wind shear of 40 to 45 knots in the lowest 2000 feet will be
a concern before the line of storms moves throughat MCB, ASD,
GPT, and HDC due to the strength of the low level jet. The line of
storms is forecast to impact BTR and MCB between 02z and 04z with
strong winds of 35 to 45 knots, lightning, and IFR ceilings and
visibilties. The line will then progress to the east and impact
HDC, MSY, NEW, ASD, and HUM with similar conditions between 04z
and 06z. GPT will be the last to see the line go through between
06z and 08z. After the line passes, lingering low stratus and some
light rain could persist for a few hours and keep MVFR conditions
in place at all of the terminals. However, a surge of drier air
into the region will lead to VFR conditions developing at nearly
all of the terminals as the cloud deck begins to break up by 12z.
However, a thermal trough over MCB where the cold pool is expected
to be deeper, could keep some lingering low stratus in place
through much of the day tomorrow with ceilings averaging near 2000
feet. PG
&&
.AVIATION...
(18Z TAFS)
Issued at 1139 AM CST Sun Jan 5 2025
Each terminal is telling a different story this afternoon.
Terminals along I10/12 northshore and MS Gulf Coast range from
LIFR to IFR. Meanwhile southshore and southwest terminals are all
VFR as clouds have dissipated. Conditions will likely improve for
all TAF sites briefly this afternoon minus some gusty southerly
winds and some potential for LLWS. However, a squall line of
thunderstorms should impact most if not all terminals (GPT is a
bit questionable for thunder at this juncture). With the line
expect brief VIS/CIG drops and strong gusty winds. It will be a
fast moving line so improvement will take place very quickly
behind the line/frontal boundary. Then northwest winds increase
and remain elevated with 20-30kt possible behind the front through
the end of the cycle. (Frye)
&&
.MARINE...
Issued at 218 PM CST Sun Jan 5 2025
A cold frontal boundary will move through the local waters later
tonight. Ahead and behind the front, hazardous marine conditions
will be present/ongoing. With the front a line of storms may
enhance winds and seas a bit. Offshore flow will develop early
Monday and winds will stay hazardous at least until early Tuesday.
Pressure gradient relaxes just a bit going into midweek or so,
however, moderate winds and seas will still be present. A gulf low
develops late this week and yes again SCA conditions may be
required as it nears the local waters. (Frye)
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 27 38 24 44 / 100 0 0 0
BTR 32 41 27 49 / 100 0 0 0
ASD 33 41 26 49 / 100 0 0 0
MSY 36 41 32 48 / 100 0 0 0
GPT 34 40 27 49 / 90 0 0 0
PQL 36 41 26 52 / 90 0 0 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Wind Advisory until midnight CST tonight for LAZ034>037-039-
046>048-056>060-064>071-076>090.
Cold Weather Advisory from midnight tonight to 9 AM CST Monday
for LAZ034>037-039-046>048-056>060-065>067-071-076>087.
GM...Small Craft Advisory until 6 AM CST Tuesday for GMZ530-532-534-
536-538-550-552-555-557-570-572-575-577.
MS...Wind Advisory until midnight CST tonight for MSZ068>071-077-
083>088.
Cold Weather Advisory from midnight tonight to 9 AM CST Monday
for MSZ068>071-077-083>088.
GM...Small Craft Advisory until 6 AM CST Tuesday for GMZ532-534-536-
538-550-552-555-557-570-572-575-577.
&&
$$
SHORT TERM...RDF
LONG TERM....RDF
AVIATION...PG
MARINE...RDF
Source:
LIX issues Area Forecast Discussion (AFD) at Jan 5, 5:37 PM CST ...New AVIATION...---------------
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