LIX issues Area Forecast Discussion (AFD) at May 27, 4:02 AM CDT ...New SHORT TERM, LONG TERM, MARINE...523
FXUS64 KLIX 270902
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
402 AM CDT Mon May 27 2024
...New SHORT TERM, LONG TERM, MARINE...
.SHORT TERM...
(Today through Tuesday)
Issued at 350 AM CDT Mon May 27 2024
Upper ridge remains over Mexico early this morning but has been
suppressed southward by a shortwave extending from the Great Lakes
to Texas. A cold front was just ahead of this trough extending
from the Great Lakes to near Shreveport to central Texas.
Scattered thunderstorms continued in a couple of bands with the
closest to the local area extending from near Meridian to Natchez
to Alexandria at 3 AM CDT. Temperatures at that time across the
local area ranged from the upper 70s to lower 80s with dew points
in the mid and upper 70s.
Dual concerns for today will be thunderstorms and heat related
issues. Ongoing convection should be somewhat elevated, if
forecast soundings are any indication. Low level winds just ahead
of the band approaching the northwest corner of the CWA have
become a bit more southwesterly, making us question the strength
of low level convergence. Most of the mesoscale modeling has the
western portion of the line weakening or dissipating prior to
sunrise, with only scattered activity potentially impacting areas
from McComb to the Mississippi coast prior to noon.
The boundary looks to become rather diffuse over the northern
portion of the CWA later this morning or afternoon with very
little in the way of low level convergence indicated by forecast
wind fields. Diurnal heating is likely to be the main trigger if
any convection is to develop. With forecast soundings indicating
convective temperatures in the mid 90s by the middle of this
afternoon, it is rather questionable as to whether convection will
develop at all. If it does, strong to severe storms with damaging
winds would become a significant concern with all the mid-level
drier air available. Any convection that does develop should wind
down pretty quickly after sunset.
Prior to the convective development, hot and humid weather will be
in place. Heat index values generally topped out in the 100-105
range yesterday, and both temperature and dew point values will be
a degree or two higher, nudging values today to right around 108
in the advisory area. With it being early season heat and outdoor
activities higher than normal, keeping the advisory in place is
the preferred path.
For Tuesday, with the weakening boundary still hanging around,
can't eliminate at least isolated thunderstorm development,
although the GFS based solution is the only one really advertising
much in the way of storms. Will hold onto the previous PoPs for
Tuesday, but confidence isn't particularly high. Somewhat drier
air should slowly filter into the area tomorrow, lowering heat
indicies somewhat, even though high temperatures will remain in
the lower and middle 90s. The highs on the Mississippi coast may
be a bit tricky depending on whether a sea breeze develops or not.
If winds remain offshore, they could reach well into the middle
90s.
&&
.LONG TERM...
(Tuesday night through Sunday)
Issued at 350 AM CDT Mon May 27 2024
Quite a bit of disagreement in medium range rain chances between
the GFS based and ECMWF based guidance. The area will be in
northwesterly mid level flow for Wednesday through at least
Friday. With the exception of agreement on a shortwave producing
thunderstorms Wednesday afternoon, the ECMWF solutions are much
drier than the GFS solutions. With the trough axis to the east of
the area, there's a tendency to downplay any convective threat,
but I've seen too many times that convection around the periphery
of a ridge tends to "overperform". We'll keep some mention of
afternoon convection in the forecast. By the weekend, the model
families flip with the ECMWF solutions the wetter choice.
High temperature forecast will obviously be tied to precipitation
chances, with the drier model solution the hotter one. For now,
will go with the NBM deterministic, hoping for better agreement
between the model families. Overnight lows should be at least
slightly more comfortable beyond Tuesday night with slightly drier
air in place.
&&
.AVIATION...
(06Z TAFS)
Issued at 1204 AM CDT Mon May 27 2024
Intermittent MVFR CIGs are likely to extend through the overnight
hours with more BKN coverage mixing in and southerly winds will
remain near 10 knots. Will be monitoring latest guidance for
trends in SH/TS activity headed into the morning hours.
Uncertainty exists regarding extent of coverage of stronger
thunderstorms starting late morning into evening and will likely
need to add and refine timing of these storms for terminals in
subsequent forecasts. Have added more emphasis on TSRA impacts to
ASD and HDC as well as highest confidence of impacts being to GPT
in the 1400-1800 UTC timeframe.
&&
.MARINE...
Issued at 350 AM CDT Mon May 27 2024
With the boundary to the north expected to weaken, the weaker
pressure gradient should allow winds to diminish a bit later this
morning. Current plan is to let Small Craft Exercise Caution
headlines expire. Once that occurs, we should be in a pattern that
will be driven by diurnal heat processes with onshore/offshore
diurnal trends. This usually doesn't result in wind speeds strong
enough to require headlines.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 92 69 92 67 / 20 10 20 10
BTR 96 75 95 72 / 30 10 30 10
ASD 94 74 94 71 / 30 10 10 10
MSY 93 77 93 75 / 40 10 20 10
GPT 90 74 93 72 / 40 10 10 10
PQL 91 72 95 69 / 30 10 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory from noon today to 8 PM CDT this evening for
LAZ034>037-039-046>048-056>060-064-065-071-076>090.
GM...None.
MS...Heat Advisory from noon today to 8 PM CDT this evening for
MSZ068-077-083-084-086-087.
GM...None.
&&
$$
SHORT TERM...RW
LONG TERM....RW
AVIATION...TJS
MARINE...RW
Source:
LIX issues Area Forecast Discussion (AFD) at May 27, 4:02 AM CDT ...New SHORT TERM, LONG TERM, MARINE...---------------
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