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Area forecast discussion 
National Weather Service New Orleans la
828 am CDT Wednesday Apr 1 2015

..sounding discussion...
There is a 7 f temperature inversion from the surface to 006 feet...
which has led to patchy fog this morning. A thin cloud deck
around 470 and 390 mb has prevented fog from becoming very
widespread. Above the surface is a relatively dry middle level air mass
with an elevated inversion at 850 mb. Precipitable water is near average at .82
inches. Winds are westerly through the profile with peak wind of
80 kts at 180 mb.


Previous discussion... /issued 355 am CDT Wednesday Apr 1 2015/

Short term...
rainfall will be hard to find over the next few days until Friday
evening. A short wave trough will move out of southern Texas and join
with the rossby wave over the tenn valley. This feature will weaken
as a more significant upper low swings through the base of the
long wave trough. Before the short wave will be
responsible for giving severe weather to the arklatex and northern Mississippi
areas Thursday. This will keep our area virtually rain free Thursday. As the
new larger Upp low moves through the long wave...a cold front will
move along with it into and through the area. High pressure on the
back side will move quickly southeast and bridge the front on the
southern end causing a subsident capping inversion. This will be
evident as the front moves into our area. At will bring
along with it a squall line with some individual cells causing
strong to severe weather for areas to our northwest. This may even get as
far south as a Baton Rouge to Picayune line Friday night. The line
will weaken rapidly as it moves farther south and the Baton Rouge
to Picayune line should be where we find the last of severe ts
chances. But I also never say never...especially during the
Spring. Storm Prediction Center has advertised extreme southern miss in a slight risk
as well so confidence is heightened a little more for this. The
cold front will pass early Sat bringing with it a new set of low
temperatures and beautiful days but a little breezy as north and NE winds
will be in the range of 15 to 20 miles per hour in some locations but could
be as high as 20 to 25 miles per hour on the Lee side of large aeras of

Fog may be an issue this morning but a cloud deck of around 20k
feet is trying very hard to move in from the west. With strong
subsidence at that level...this deck should erode this morning
over our area helping fog to form. Hard to say at the moment if
it will be again Thursday morning. The only variable to overcome will
be cloud cover as an 1800-2800 foot level will try to form
keeping warmth locked up in the bl which will prevent fog from
forming. Have not shown any fog in forecasted grids at this time
for Thursday. But if cloud cover does not show...the fog will be a go.

Long term...
the next chance of sh/ts will come Monday with moisture loading
ahead of the next cold front. At this moment...this cold front
which looks to move through next Friday...looks a little more
significant with respect to severity. But the support for this
feature is also well out over the Pacific and we have no way of
sampling the jet dynamics until that jet moves over a radiosonde observation site.
Will have to wait and see on this one as future forecasts could change
quite a bit.


VFR conditions again rule at most terminals this morning. Current
exception is khum where LIFR conditions are being reported. A few
non forecast points reporting MVFR...namely knbg and kgao. Same
story as the past few days. Where clouds and/or wind are being
reported...generally no fog. Where winds go calm and skies
clear...fog sets in. It was notable yesterday that most areas that
reported fog did not start to see it until after 11z. Most terminals
are seeing relatively small temperature and dew point
if winds go calm...we would be looking at a repeat of yesterdays
scenario. Will continue current forecast trends with respect to fog
but will be continuing to monitor closely until 12z taf package GOES
out. Do not anticipate any convection today...but will probably see
a well developed cumulus field by 18z. Little change in the pattern
and moisture levels overnight cannot preclude fog
occurring again. 35


Relatively benign conditions for the 36 hours or so winds not much
more than 10-12 knots. Pressure gradient will tighten the wind field
somewhat as a cold front approaches the area Thursday into
Friday...then moves through the coastal waters Friday night. Expect
that we will need a Small Craft Advisory for Saturday into Sunday
for some or all of the coastal waters. 35

Decision support...

Decision support services (dss) code legend
green = no weather impacts that require action
blue = long fused watch/warning/advisory in effect or high
visibility event
yellow = heightened impacts with short fused
watch/warning/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 tonight risk severe
and/or direct tropical threats; events of National


Preliminary point temps/pops...
mcb 81 63 82 65 / 10 20 20 10
btr 81 64 84 66 / 10 20 20 10
asd 81 66 81 66 / 10 10 10 10
msy 80 67 82 68 / 10 10 10 10
gpt 77 65 77 67 / 10 10 10 10
pql 79 66 79 65 / 10 10 10 10


Lix watches/warnings/advisories...


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