Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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FXUS64 KLIX 300855
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
355 AM CDT Fri Jul 30 2021

.SYNOPSIS...

Upper ridging continues to be centered over Kansas and Oklahoma,
extending southeastward toward Mobile. A weak frontal boundary is
well to the north of the area along Interstate 70. There is the
usual smattering of isolated nocturnal convection over the Gulf
of Mexico, with organized complexes over Missouri, and over the
Gulf well to the south of Pensacola. Temperatures at 3 AM
generally ranged from the mid 70s to lower 80s.

&&

.SHORT TERM (through Sunday night)...

Main concern over the next 48 hours or so will be the heat.
Convective threat for today appears to be rather limited, both in
areal coverage and duration. Convection allowing models don`t
really show much development prior to about 21z, and the 20-30% we
have in the forecast may even be too high. This is likely to allow
high temperatures in the mid to upper 90s. Only question is
whether drier air mixes down to the surface to lower dew points
somewhat. Heat index values would be somewhat borderline for
Excessive Heat Warnings just on the face of things, but
considering we have been in advisories for about 5 days already,
the cumulative effect of heat stress argues for the higher threat
level. Have expanded the warning to include the Baton Rouge Metro
and areas to the north and west in coordination with the Lake
Charles and Jackson offices today. Have also opted to place the
lower portions of the Louisiana coastal parishes in the Heat
Advisory.

For Saturday, the heat will continue to be a problem, but won`t
make any adjustments to advisories or watches for now until we see
how today plays out. Somewhat of a challenging forecast
convectively on Saturday, as the GFS solution carries considerably
more convection than the remaining solutions. GFS is considerably
further south than the remaining solutions. Moisture levels will
be higher tomorrow than today as noted by higher precipitable
water levels on forecast soundings. The GFS solution with it`s
higher precipitation chances would not support heat
advisories/warnings, but the NAM/ECMWF/NBM solutions with their
lower chances would. Will trend below GFS PoP solution, thus
higher temperatures.

A little better rain chances on Sunday as upper troughing and
surface boundary move closer to the area. Should be enough to back
the temperatures down a couple degrees. 35

&&

.LONG TERM (Monday and beyond)...

A rather deep mid/upper longwave trough for early August will
amplify down into the southeast U.S. and northeast Gulf coast during
the early to middle of the upcoming week. This will send a weak cold
front down into the forecast area. This frontal boundary will likely
move slowly towards and into the area on Monday into Tuesday, so
that is likely to be two wetter days with high rain chances and
potential for locally heavy rainfall. The front may move far enough
south into coastal areas to actually bring drier conditions over at
least northern areas Tuesday night into Wednesday and possibly
Thursday as well, however the NBM guidance does not completely lower
the rain chances as aggressively as the operational runs of the
models. Have stayed very close to the NBM as it appears to be
factoring what is likely a bias of the operational runs showing too
much integrity to an early August front with regards to the lowering
of lower temperatures. 22/TD

&&

.AVIATION (12z TAF package)...

VFR conditions are expected to prevail today. SHRA/TSRA are
expected to be mostly isolated in the afternoon, so have only
placed VCTS in the TAF package during the 18z-00z period.

&&

.MARINE...

Main concern will remain the threat of convection through the
forecast period. Outside of convection, wind/wave conditions are
not expected to produce significant issues.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  96  77  96  76 /  20  10  30  10
BTR  96  78  95  77 /  20  10  40  10
ASD  96  79  97  79 /  20  10  40  20
MSY  97  83  97  82 /  30  10  50  20
GPT  96  80  95  79 /  20  10  40  20
PQL  97  79  97  79 /  20  10  40  20

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory from 9 AM this morning to 7 PM CDT this evening
     for LAZ066>069.

     Excessive Heat Warning from 9 AM this morning to 7 PM CDT this
     evening for LAZ034>037-039-046>050-056>061-063>065-070>072-
     075>078.

     Excessive Heat Watch from Saturday morning through Saturday
     evening for LAZ037-039-049-050-056>061-063>065-070>072-
     075>078.

     Heat Advisory from 9 AM to 7 PM CDT Saturday for LAZ034>036-
     046>048.

GM...None.
MS...Excessive Heat Warning from 9 AM this morning to 7 PM CDT this
     evening for MSZ068>071-077-080>082.

     Excessive Heat Watch from Saturday morning through Saturday
     evening for MSZ070-071-077-080>082.

     Heat Advisory from 9 AM to 7 PM CDT Saturday for MSZ068-069.

GM...None.
&&

$$


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