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

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230
FXUS64 KLIX 280539
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1139 PM CST Fri Nov 27 2020

.SHORT TERM...

Removed mention of thunder overnight for most of CWA as front is
pretty much off the coast for now. No changes to later forecast
periods.

&&

.LONG TERM (Tuesday and beyond)...

Tuesday morning will be the coldest morning in a long time across
most of the area. Freezes possible, if not likely, north and west
of Lake Pontchartrain. High pressure moves from the Texas coast
Tuesday morning to off the Atlantic Coast by Thursday night. At
that point, models begin to diverge. 18z and 00z GFS solutions
emphasize northern stream shortwave at the end of next week,
while the 12z ECMWF emphasizes southern stream shortwave. While
both models return moisture to the area Wednesday night and
Thursday, with an attendant chance of precipitation, the GFS
solution would start it about 12 hours earlier. In addition, the
ECMWF solution would develop a significant surface low over the
Gulf in our coastal waters as the northern and southern streams
phase, strengthening the surface low it as it heads toward the
Florida Panhandle Friday. The GFS is basically an inverted trough
with surface pressures at least 10 mb higher.

Will take the middle ground on timing with no mention of
precipitation until Wednesday night, mainly after midnight. Would
note that if 12z ECMWF scenario becomes the preferred solution,
PoPs and winds from Wednesday night onward would need to be bumped
up significantly from current levels.

Only real disagreement on temperatures through Friday will be for
Thursday and Thursday night, which can be attributed to the vastly
different surface patterns. Current forecast is in between the 2
solutions, so we can go either way depending on favored solution
in later packages. 35

&&

.AVIATION (06z TAF Package)...

Most terminals running MVFR to VFR this evening as main convection
has moved offshore. Still some elevated precipitation across
northwest half of area and no indications of any lightning
involved with this. Starting to see IFR ceilings sinking
southward across KMCB, and will probably reach KBTR/KHDC/KASD by
about 09z. Will be cutting way back on mention of precipitation in
TAF set until at least 00z Sunday, and maybe even closer to 06z.
Based on 00z MOS guidance from NAM and GFS, won`t carry TSRA at
any terminal for now. Morning IFR conditions should improve to
MVFR and potentially VFR prior to 18z. Conditions will again
deteriorate from the west as we approach 06z Sunday, likely to
upper end IFR. 35

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  61  69  58  69 /  80  20  90  90
BTR  62  69  60  71 /  80  40  90  90
ASD  62  71  59  73 /  80  30  80  90
MSY  65  70  64  73 /  80  40  80  80
GPT  64  71  61  72 /  90  30  80  90
PQL  62  73  59  74 /  90  20  70  90

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

$$



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