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

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FXUS64 KLIX 271706
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1206 PM CDT Thu Jul 27 2017

.AVIATION...
VFR conditions expected to prevail at all terminals next 24-30
hours. Exception may be briefly at KMCB near daybreak on what can
be disputed as either BR or HZ in stagnant moist airmass for 5SM
MVFR conditions that improve as mixed layer increases. 24/RR

&&


.PREV DISCUSSION... /issued 746 AM CDT Thu Jul 27 2017/

..SOUNDING DISCUSSION...
There is drier air through the profile this morning with below
average PW down to 1.5 inches. This will allow for mostly clear
skies today and quick heating this morning. A couple showers are
possible today, but stable layers are forming from subsidence
inversions around 850 and 580 mb. Winds are light and variable
through low and mid levels then become northeast above 300 mb.

Krautmann

PREV DISCUSSION... /issued 441 AM CDT Thu Jul 27 2017/

SHORT TERM...
Activity continues to wind down as more dry air enters the picture
from the south. The dry air is associated with the high over the
gulf riding into the area. The dry air layer that has moved into
the region is from 1012 to 980mb. This has simply capped the area
keeping sh/ts activity to a minimum. But the 20% that do occur
will be capable of strong gusty winds due to the dry air
entrainment and very heavy rain. This high has also kept dew pt
temps lower over our area by drier air mixing down into the
boundary layer. This has prevented heat index values from getting
out of hand, but it also allows for more intense heating.
Admittedly, it is strange to see higher dew pt temps north of the
area while noticeably lower here which is also why there are heat
advisories north of the area.

A cold front will move through the area Saturday. Timing is
becoming better coordinated by model guidance and shows the cold
front entering the northern portion of the area around 7pm
Saturday then moving to the coast by daylight Sunday morning. Dew
pt temps are not fitting well with climo guidance, but will fall
more in line with short term observed guidance since it is July
and rare for a rather strong cold front to make its way into the
gulf. Dew pt temps should drop back to the lower 60s for most by
Sunday morning. Basically, we will go to sleep Saturday night with
muggy conditions and wake to what will be relatively very
comfortable conditions. Daytime highs will be cut somewhat, but
with a high zenith, temps won`t be dropping too far as the air
behind the front will be greatly modified. Widespread sh/ts will
be associated with this front and should be in a linear format
moving into the area from the north. Models are not showing any
robust dynamics associated with this front as it moves through,
but this time of year and northerly flow has been known to be
deceptive so we can not rule out any particular area observing a
strong or severe thunderstorm especially after a full day of
heating before the line of sh/ts moves in. The dry conditions
behind the front will also put a lid on the precip chances as well
until about Wednesday when south winds will return moisture and
sh/ts to the area once again.

AVIATION...
With exception to isolated locations showing 3sm BR this morning,
VFR will remain through this taf cycle.

MARINE...
Winds will be diurnally driven through Friday. This will show up
as a more northerly flow during the late night into morning hours
then becoming westerly during the daylight hours. As a cold front
moves toward the coast Friday night into Saturday, westerly winds
will begin to elevate to 15-20kt ahead of the front then weaken
as the front moves through as well as post frontal. Southerly
winds are expected to once again become established by Wednesday
of next week.

DECISION SUPPORT...
DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Monitoring river flooding

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  94  72  92  74 /  10  10  10  30
BTR  95  73  93  75 /  10  10  10  30
ASD  95  75  93  76 /  20  10  10  30
MSY  94  76  93  76 /  20  10  10  20
GPT  93  77  91  77 /  20  10  10  30
PQL  94  75  92  76 /  20  10  10  30

&&

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

$$


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