LIX issues Area Forecast Discussion (AFD) at Feb 17, 3:15 PM CST ...New SHORT TERM, LONG TERM, MARINE...
044
FXUS64 KLIX 172115
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
315 PM CST Mon Feb 17 2025
...New SHORT TERM, LONG TERM, MARINE...
.KEY MESSAGES...
1 - Marginal threat of excessive rainfall and severe weather
overnight Tuesday night into Wednesday morning. Widespread
rain amounts of two inches or more are possible across the
area, which could cause some runoff issues, especially in
urban areas. Main severe weather concern would be hail
near quarter size.
2 - A strong cold front will bring widespread freeze conditions
to most of the area Wednesday night and again Thursday
night. This is likely to include portions of the New
Orleans metro area, with potential for hard freeze
conditions across SW MS and portions of SE LA near and
north of Interstate 12. Wind chill values in the teens
and lower 20s are likely across much of the area both
Wednesday night and Thursday night. Expectation is that
Cold Weather Advisories will be necessary for just about
the entire CWA both nights.
&&
.SHORT TERM...
(This evening through Tuesday night)
Issued at 300 PM CST Mon Feb 17 2025
Upper flow is generally zonal across the southern half of the
country this afternoon. At the surface, high pressure extended
from the Canadian Prairie Provinces to the lower Mississippi River
Valley. Clear skies across the area this afternoon with
temperatures generally in the mid and upper 50s.
Tonight will remain mostly clear with surface winds gradually
coming around to the east. Temperatures may not be quite as cold
as this morning, but won't rule out isolated readings near
freezing, especially in the Pascagoula River drainage region in
Jackson County.
Isentropic processes will bring a lowering cloud deck to the area
during the daytime hours Tuesday, with light rain potentially
reaching the surface prior to sunset Tuesday. With the baroclinic
zone likely remaining off the Louisiana coastline Tuesday and
Tuesday night, a developing surface wave is likely to move
eastward along this zone toward the area Tuesday night.
Precipitable water values are expected to increase to the 75th to
90th percentile climatologically (1.25 to 1.6 inches). With the
warm, moist air getting advected over the cold airmass, elevated,
embedded convection is expected to develop. At this time, it
appears that any surface based convection is likely to remain
offshore, with the possible exception of lower Plaquemines Parish.
That leaves hail (up to an inch in diameter) as a potential
concern. Widespread rain amounts of around 2 inches can be
expected from Tuesday evening into Wednesday morning, with a few
spot totals in excess of 3 inches. Could be some isolated runoff
issues, especially in urban areas, but most areas have seen an
inch or less of rain over the last couple weeks. At this time, a
Flood Watch is not anticipated.
High temperatures Tuesday are expected to be warmer than today's
readings, but are somewhat dependent on how quickly the clouds
thicken and lower. A few hours difference in timing could be the
difference between highs in the upper 50s and highs in the mid
60s. Temperatures will drop off somewhat Tuesday evening as
precipitation onsets, before flattening out until after the
passage of the surface wave. Across southern portions of the area
near the baroclinic zone, temperatures could even rise a bit after
midnight.
&&
.LONG TERM...
(Wednesday through Sunday night)
Issued at 300 PM CST Mon Feb 17 2025
With the passage of the surface wave to the east of the area Wednesday
morning, precipitation will end, and the arctic airmass will
arrive. Little, if any, recovery in temperatures is expected
during the daytime hours Wednesday, especially if clouds hold in
all day as expected. It's entirely possible that the highs for
the day could occur before most folks get out of bed Wednesday
morning. Sub-freezing temperatures will be likely for most of the
area both Thursday and Friday mornings, with hard freeze
conditions likely, especially Friday morning, for at least the
northern half of the area. It won't be as cold as the January cold
wave, but considering the warmth of the last couple weeks, it is
going to be a shock to both vegetation, which had already started
greening up, and to people. Entirely possible that record lows
will be threatened in some areas, especially Friday morning. Wind
chill values in the teens and 20s are likely Thursday and Friday
mornings. Cold Weather Advisories for much of the area are almost
certain to be issued in later forecast packages for those
mornings. Sunshine should allow temperatures to moderate somewhat
by Friday afternoon.
Another shortwave moving near the Gulf Coast may spread some light
precipitation into the area by Saturday afternoon or Saturday
night, but temperatures should have moderated sufficiently to
eliminate the potential for freezing or frozen precipitation.
Temperature forecast is going to be a battle for the second half
of the week. As noted above, we may not see any recovery
Wednesday. For Thursday and Friday, current numbers are a blended
solution, somewhat toward the non-ECMWF solution, but can't
discount those, as there is quite a bit of agreement within the
ECMWF ensemble. By Sunday into early next week, temperatures will
have moderated to near or above normal.
&&
.AVIATION...
(18Z TAFS)
Issued at 1138 AM CST Mon Feb 17 2025
VFR conditions expected through the forecast period. Expect to see
a mid-level cloud deck move in by late morning Tuesday, with
ceilings lowering to perhaps FL050 by late afternoon. Could see
some -RA by late afternoon as well, but don't expect any flight
restrictions until after sunset Tuesday.
&&
.MARINE...
Issued at 300 PM CST Mon Feb 17 2025
Wind conditions have relaxed across the waters, but this is only a
brief respite. Easterly winds are expected to increase during the
day Tuesday, and Small Craft Exercise Caution headlines, and
possibly Small Craft Advisories, are likely to be needed by
tomorrow afternoon across the western waters.
Mariners should expect a prolonged period of hazardous conditions
across most waters from Tuesday afternoon or Tuesday night into at
least Friday morning, before there's significant improvement in
conditions.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 34 63 41 48 / 0 10 100 20
BTR 39 65 45 53 / 0 20 100 10
ASD 36 64 49 57 / 0 10 100 40
MSY 44 64 51 58 / 0 10 100 40
GPT 38 62 46 57 / 0 10 100 60
PQL 35 65 47 60 / 0 10 100 70
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
SHORT TERM...RW
LONG TERM....RW
AVIATION...RW
MARINE...RW
Source: LIX issues Area Forecast Discussion (AFD) at Feb 17, 3:15 PM CST ...New SHORT TERM, LONG TERM, MARINE... (https://mesonet.agron.iastate.edu/p.php?pid=202502172115-KLIX-FXUS64-AFDLIX)
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