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

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FXUS64 KLIX 070936
AFDLIX

AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
336 AM CST Wed Dec 7 2016

.SHORT TERM...
Fairly benign weather expected today with generally zonal flow in
place. Weak pressure field overhead will keep winds light as well.
GOES 11u-3.9u satellite imagery shows low level clouds covering most
of the forecast area. Moisture profile indicates cloud cover will
stay in place through noon, with some thinning in the afternoon
hours. GFS sounding shows the same thing as do MAV guidance. Points
further east close to coastal Mississippi look to see more sunny
skies. All in all, cloud cover and not much change in 500mb heights
should lead to only a slight increase in daytime highs compared to
yesterday.

A broad long wave trough, enhanced by upper low near the Great
Lakes, will surge southward out of Canada into the central U.S.
tonight. This will send a very strong cold front through the region
on Thursday. Models still agree on timing with both bringing the
frontal wind shift in to the CWA sometime around sunrise, give or
take a few hours. Airmass change should be fairly close to the
leading edge of these winds. Models also better in-line with precip
output. With such limited moisture in place due to small window of
southerly winds to increase moisture, preferred the output of the
GFS. Now the ECMWF, which had been showing much more qpf than the
GFS, looks similar. Showers will move in across northwestern
forecast zones with decreasing coverage as the cold front moves
south. Since precip will be post-frontal, lightning is quite
unlikely. Total rainfall amounts should be less than 0.1".


.LONG TERM...
The following 2 days will be dominated by strong cold air advection
as 1030+mb surface high builds into the region. A drastic drop in
temperatures will ensue, with highs struggling upper 40s to mid 50s
Thursday and likely not even up to 50 on Friday. Nighttime lows are
looking to be in the mid/upper 20s along I-12 and north in LA and
all of coastal MS. South of there probably just above freezing to
upper 30s. Attm, not thinking a freeze warning will be needed as
areas which will see freezing or below, have already seen 1 or 2
freezes.

A warming trend will bring temperatures back to near normal over the
weekend as the upper trough axis exits the East Coast and surface
low shifts east. Models show a more northern stream upper level
trough will quickly track east across the country late this weekend
into early next week. Moisture returning to the area along with the
approach of another frontal boundary will lead to the next chance of
rain for the area.

Meffer
&&
.AVIATION...

A few terminals will continue with ceilings as low as ovc003. The
remaining sites mainly east will keep bkn010 during the morning.
Not much difference will be observed in the pattern through the next
24 hours. Ceilings will raise to around bkn-ovc030 and fall once
again tonight to decks around ovc005. The next cold front comes in a
little after 12z Thursday.

&&

.MARINE...

A strong arctic cold front will sweep through the coastal waters on
Thursday. This front will produce another around of SCA winds of 20
to 30 knots beginning Thursday and persisting through Friday
evening. Have contemplated the issuance of a gale watch, not for
sustained winds of 34+kt but for very frequent gusts to gale force.
This will especially be noticed at platform height. Would like to
see winds sustained up to at least 30kt before introducing a gale
watch at this time. But highest sustained winds look to be 25kt.
This normally is indicative of sustained winds at 25-30kt with gusts
over gale force starting Thursnight into Friday. Would like to see
if 12z or 00z model runs show a few 30kt sustained wind speeds. This
would greatly increase confidence levels to institute a gale
watch possible warning.

As high pressure settles in over the weekend, winds should turn more
easterly. However, exercise caution conditions should persist as
winds remain in the 15 to 20 knot range offshore.

&&

DECISION SUPPORT...

DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.

Decision Support Services (DSS) Code Legend
Green  = No weather impacts that require action.
Blue   = Long-fused watch, warning, or advisory in effect or
         high visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
         advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
         tropical events; HazMat or other large episodes.
Red    = Full engagement for Moderate risk of severe and/or
         direct tropical threats; Events of National Significance.


&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  64  45  48  28 /   0  20  30   0
BTR  67  49  51  32 /   0  30  30   0
ASD  66  47  55  32 /   0  20  30   0
MSY  66  51  56  37 /   0  30  30   0
GPT  65  50  57  35 /   0  10  30   0
PQL  64  46  57  32 /   0  10  20   0

&&

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

$$



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