LIX issues Area Forecast Discussion (AFD) at Dec 5, 6:39 AM CST ...New UPDATE...468
FXUS64 KLIX 051239
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
639 AM CST Thu Dec 5 2024
...New UPDATE...
.UPDATE...
Issued at 635 AM CST Thu Dec 5 2024
Main area of rain shifting quickly offshore. With no lightning
strikes over land in the last couple hours and no significant
instability in 12z upper air soundings, have removed thunder from
the forecast over land and changed mention from convective to
stratiform. ZFPLIX has already been transmitted. Will update other
products to remove mention of thunder.
&&
.SHORT TERM...
(Today through Friday)
Issued at 329 AM CST Thu Dec 5 2024
Main upper trough is over the central Great Lakes, with a southern
stream shortwave moving through the local area, and another near
Phoenix undercutting a ridge over the Intermountain West. a
frontal boundary or inverted trough was over western Louisiana at
3 AM CST. Rain was moving through the local area with potentially
a few rumbles of thunder south of Interstate 10. Temperatures
were generally in the upper 50s and lower 60s, although Houma was
at 65 degrees.
The shortwave should exit the area this morning, taking any
significant precipitation with it. The frontal boundary or trough
axis should also clear the area late this morning or this
afternoon with cold advection in it's wake. Model forecasts have
finally come into somewhat better agreement on post-frontal
temperatures, and they will be on the cold side. With winds not
expected to entirely decouple overnight, wind chills will be
somewhat lower than ambient air temperatures. Considering our Cole
Weather Advisory criteria (temperature and/or wind chills) of 25F
or lower along and south of the Interstate 10 and 12 corridors,
and 20F north of there, have issued an Advisory from Interstate
55 eastward north of Lake Pontchartrain, including the Mississippi
Coast.
Although we'll have plenty of sunshine Friday, it's not exactly
going to be a warm day, with highs only in the lower and middle
50s, and that might be ambitious.
&&
.LONG TERM...
(Friday night through Wednesday)
Issued at 329 AM CST Thu Dec 5 2024
Surface high shifts east of the area pretty quickly Friday night
and Saturday, with surface winds turning easterly and moisture
beginning to return along with warm advection aloft even as early
as late Friday night. A few patches of light rain may be possible
by Saturday afternoon or evening. The main period of precipitation
will be Sunday night and Monday as the shortwave currently near
Phoenix moves across the area. Precipitable water values will
increase to the 1.6 to 1.8 range on Sunday. Just as with the
current system, the airmass will be rather saturated, with a fair
amount of shear. However, again, just as with the current system,
instability is expected to be somewhere between meager and non-
existent. So it should be primarily rain showers with only a few
rumbles of thunder. Rain amounts of 2 to 3 inches certainly look
reasonable. With this morning's rainfall priming the pump a bit,
that amount of rain could cause at least some minor issues.
A strong northern stream shortwave is expected to impact the area
next Tuesday night or Wednesday, with another round of at least
scattered showers and storms possible. However, moisture appears
to be insufficient for major concerns as we never get into a
situation where there is a strong moisture return ahead of that
trough.
That trough and frontal passage will definitely have some cold air
behind it, but it doesn't appear to be any colder than the one
behind this rain, and it looks to be short lived.
Temperatures look to be in reasonable agreement, especially when
considering how far apart they've been the last several runs. No
major adjustments made to NBM deterministic values.
&&
.AVIATION...
(12Z TAFS)
Issued at 533 AM CST Thu Dec 5 2024
Northern terminals are reporting IFR or lower ceilings but good
visibilities. Any steady precipitation will likely be southeast of
all terminals in the next hour or so. However, do expect IFR to
MVFR ceilings for most of the morning into the afternoon until
drier air arrives. VFR conditions likely overnight tonight, but
northerly winds off of Lake Pontchartrain are likely to produce 25
to 30 knots wind gusts at KNEW and possibly KMSY before relaxing
Friday morning.
&&
.MARINE...
Issued at 329 AM CST Thu Dec 5 2024
Will keep current Small Craft Advisory parameters in place,
although there's some potential it may eventually need extended 6
hours or so on the back end. Likely to be at least an additional
period or two beyond the advisory where we will need Small Craft
Exercise Caution headlines. We shouldn't get back into Small Craft
Advisory issuances until one of the frontal systems next week,
probably the one Tuesday night and Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 57 26 50 31 / 50 0 0 10
BTR 65 33 56 38 / 40 0 0 0
ASD 66 31 54 34 / 80 0 0 0
MSY 66 38 52 43 / 80 0 0 0
GPT 65 32 53 36 / 90 0 0 0
PQL 67 30 56 33 / 90 0 0 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Cold Weather Advisory from midnight tonight to 8 AM CST Friday
for LAZ039-071-076-079>082.
GM...Small Craft Advisory from noon today to 6 AM CST Friday for
GMZ530-532-534-536-538-557.
Small Craft Advisory from 3 PM this afternoon to 6 AM CST Friday
for GMZ550-552-555-570-572-575-577.
MS...Cold Weather Advisory from midnight tonight to 8 AM CST Friday
for MSZ070-071-077-083>088.
GM...Small Craft Advisory from noon today to 6 AM CST Friday for
GMZ532-534-536-538-557.
Small Craft Advisory from 3 PM this afternoon to 6 AM CST Friday
for GMZ552-555-570-572-575-577.
&&
$$
SHORT TERM...RW
LONG TERM....RW
AVIATION...RW
MARINE...RW
Source:
LIX issues Area Forecast Discussion (AFD) at Dec 5, 6:39 AM CST ...New UPDATE...---------------
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