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

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FXUS64 KLIX 211716

Area Forecast Discussion
National Weather Service New Orleans LA
1216 PM CDT Fri Oct 21 2016

...18Z AVIATION...

VFR conditions will prevail through the TAF period. Gusty winds
from the north-northeast and north will subside later this
afternoon, though it will remain breezy through this evening at
KNEW and to a lesser extent at KMSY.



.PREV DISCUSSION... /issued 755 AM CDT Fri Oct 21 2016/


Three words...cold air advection. The wind profile is backing as
the winds in the low levels are from the north-northeast and then
rotate counter-clockwise to the northwest and finally west in the
upper levels. Wind speeds sampled above the surface average
between 35 to 40 knots. Some of these gust, though perhaps not as
strong, may be able to mix down before winds begin to abate during
the day. The surface temperature is about 10 degrees lower than 24
hours ago and about 20 degrees lower than 12 hours ago. An
elevated inversion begins at 1500 feet and extends to about 4300
feet with an additional, weak inversion centered around 7650 feet.
The precipitable water value has plummeted by almost an inch to
0.42 inches and is well below normal for this part of October.

12z balloon info: A successful flight that reached a height of
20.6 miles above the ground bursting near Cat Island 39 miles
downrange from the office. The ascent lasted 107 minutes.


PREV DISCUSSION... /issued 356 AM CDT Fri Oct 21 2016/

A strong cold front that entered the forecast area yesterday has
pushed through, just now passing the mouth of the Mississippi
River. Some locations have dropped as much as 25 degrees so far
overnight. Strong cold air advection today will lead to limited
warming, so went on the colder side of guidance. Highs today will
generally be in the lower to mid 70s. Actual numbers are a couple
degrees colder than the previous forecast. Another repercussion of
CAA will be strong and gusty winds, especially on the southshore
of Lake Pontchartrain this morning. Latest observations in the New
Orleans metro show wind speeds in the mid 20s with higher gusts.
Those gusts could touch 40 mph along the lakefront. So will be
issuing a wind advisory for parishes along Lake Pontchartrain.
Winds will begin relaxing in the afternoon hours as the surface
ridge center moves in closer and the gradient relaxes slightly.
Temperatures will drastically drop Friday night, falling into the
mid 40s for much of the CWA as the post frontal air mass moves in.

Cooler conditions will continue into Saturday as the upper trough
amplifies while tracking east and surface ridge builds in behind it.
Highs Saturday look to be about the same as today but even colder
going into the overnight hours. Blended model guidance likely way to
warm in a cold air drainage pattern that the area will be in with
the surface ridge centered to the northeast. So went with a bias
corrected MOS/MEX combo with some individual tweaking. A few
locations in coastal/SW Mississippi will see upper 30s and lower 40s
reaching as far south as the I-12 corridor. Temperatures will begin
moderating Sunday onward as upper trough exits and ridge builds back
in from the west. A northern clipper trough passing across the upper
Mississippi Valley mid week will break down the upper ridge
overhead which may open up the area to a few coastal showers.


With the passage of the cold front last night strong offshore
winds quickly developed. Small craft advisories are currently in
effect for all locations through this afternoon. By this afternoon
winds should begin to relax, especially over the tidal lakes, but
have opted to extend the advisory a few more hours over the tidal
lakes as mdls indicate winds just above the sfc will still be
around 25 kts with weak cold air advection still occurring. Cold
air advection should begin slack off early this evening as high
pressure sits in over the region. Much quieter conditions will be
in place after tonight. /CAB/

The period of MVFR ceilings has about cleared up with cigs hghts
improving at all locations and even clearing out. VFR conditions
will then prevail for the remainder of the TAf forecast period.
Breezy to windy conditions are expected through the day Friday,
particularly downwind of Lake Pontchartrain at KNEW and KMSY. 11


DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Small Craft Advisory

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.


MCB  44  74  42  79 /   0   0   0   0
BTR  46  75  44  81 /   0   0   0   0
ASD  45  75  41  78 /   0   0   0   0
MSY  53  73  52  80 /   0   0   0   0
GPT  48  73  45  75 /   0   0   0   0
PQL  44  76  38  78 /   0   0   0   0


LA...Wind Advisory until 1 PM CDT this afternoon for LAZ058-060>062-

GM...Small Craft Advisory until 1 AM CDT Saturday for GMZ532-534-536-

     Small Craft Advisory until 4 PM CDT this afternoon for GMZ530.

GM...Small Craft Advisory until 1 AM CDT Saturday for GMZ534-536-538-


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