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000 
FXUS64 KLIX 200516
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1116 PM CST Tue Nov 19 2019

...UPDATED AVIATION DISCUSSION...

&&

..EVENING UPDATE... /issued 718 PM CST Tue Nov 19 2019/ 

Performed a gridded forecast update this evening - with the main 
focus being forecast lows tomorrow morning/highs tomorrow 
afternoon and dense fog potential early AM. 

Taking a look at the latest 00Z HRRR guidance valid for 12Z 
tomorrow morning, comparing it to what was initialized in the 12Z 
run yesterday morning shows a similar overall atmospheric profile.
Only notable difference is a slightly stronger surface subsidence
inversion and a bit more of a southerly surface to low-level flow
developing (to around 1,000ft AGL). Given this, areas of dense 
fog will likely develop again around the same areas as last night 
(generally along/west of I-55 including the southshore and coastal
southern Louisiana). Will likely issue a Dense Fog Advisory later
tonight before 10PM to get an early heads up for those traveling 
early tomorrow morning, with possible expansion where needed as 
observations indicate. 

Similar to last night, blended guidance continues to come in a 
bit too warm with overnight lows. Dropped temperatures slightly 
(not as much as last night) with focus on area drainages from the 
northshore east across the MS coast). Blended guidance still is 
struggling with afternoon highs a bit, as some locations today 
reached the mid to upper 70's - which confirms this cooler bias. 
Have manually bumped up highs tomorrow to a more realistic 
forecast. KLG

.PREV DISCUSSION... /issued 332 PM CST Tue Nov 19 2019/ 

High pressure is in place and will persist through Thursday. This
high pressure is bringing drier air and a bit warmer air into the
region for the next few days. Wednesday and Thursday, winds will
primarily be southerly, bringing in some moisture from the Gulf
into the region as well. 

Friday and Friday night, a low pressure system will move through 
the area. Winds leading up to the event will remain southerly,
continuing to fuel moisture into the area. Some upper level
divergence will help to provide some lifting for the area Friday.
The abundant moisture presence combined with the lifting will
further be enhanced by the front, however, this front currently
seems weak, looking at the models. As a result, there will likely
be rain showers with the chance of a thunderstorm Friday and 
Friday night. 

If the front remains weak like the models show, then the threat of 
severe weather would be low. The main threat if the front remains
weak would just be rain and scattered thunderstorms. In addition,
some gusty winds and frequent lightning would be a concern Friday
and Friday night as well. 

Saturday through the beginning of next week, high pressure builds
in, which will help to stabilize the atmosphere. In general, this
stable air will help to dry out the area, so the rain chances are
pretty low for the beginning of next week again. MSW

.AVIATION...

.UPDATED 0516Z...

Main focus tonight will be patchy dense fog, primarily for areas 
along and west of I-55 and especially south of I-10/12. Main 
impacts for area terminals will be periods of reduced visibility 
at the surface, leading to IFR/LIFR flight categories. Otherwise,
any area fog will likely dissipate shortly after sunrise (or 
after 13-14Z) revealing prevailing VFR conditions throughout the 
day/rest of the forecast period. KLG 

.MARINE...

Winds will be variable today, shifting to southeasterly tonight
and tomorrow and calm (<15 knots). Winds will be southerly and 
light (<15 knots) through Saturday. Saturday through Sunday, winds
will be stronger (15-20 knots) and northerly. Sunday
through early Tuesday morning, winds will be northerly and calm
(<15 knots). Tuesday through Wednesday, winds will be southerly
and stronger (15-20 knots). Wave heights will correspond with the
wind speeds. MSW

.DECISION SUPPORT...

DSS code: Blue. 
Deployed: None. 
Activation: None. 
Activities: Fog Advisory through 8AM.

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; Marginal risk severe or excessive rain.
Yellow = Heightened impacts with short-fused watch, warning or 
         advisory issuances; radar support for slight risk severe 
         or excessive rain.
Orange = High Impacts; Enhanced risk severe; nearby tropical 
         events; HazMat or other large episodes.
Red    = Full engagement for Moderate to high risk of severe and/or 
         excessive rainfall, or direct tropical threats; Events of 
         National Significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  45  75  50  74 /   0   0   0   0 
BTR  46  78  53  77 /   0   0   0   0 
ASD  44  75  50  75 /   0   0   0   0 
MSY  51  75  56  75 /   0   0   0   0 
GPT  47  72  52  72 /   0   0   0   0 
PQL  43  75  49  75 /   0   0   0   0 

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Dense Fog Advisory until 8 AM CST Wednesday for LAZ046-049-
     056>061-063-065>069.

GM...None.

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