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Area forecast discussion 
National Weather Service New Orleans la
655 am CST Sat Jan 31 2015

..sounding discussion...

Once again there is a strong temperature inversion and this
morning it is from the surface to 3200 feet of 9 degrees celsius.
The low-levels are quite dry and this is a layer where winds are
predominately from the east and southeast due to the area of
surface high pressure moving east across the Tennessee and Ohio
valleys. Toward the top of this dry air above 14000 feet...winds
switch and become from the west and northwest. This is bringing in
more moist air from our next weather system to our west entering
the Southern Plains. A peak wind speed of 75 knots was located near
40700 feet.

12z balloon info: a routine flight this morning lasting 104 minutes.
The balloon reached a height of 20.4 miles above the ground before
bursting near Ship Island 52 miles downrange from the office.



Previous discussion... /issued 430 am CST Sat Jan 31 2015/

Short term...other than more high clouds overnight than was
expected it has been quiet. This has had an obvious hit on temperatures
with morning lows likely going to be about 5 degrees or so warmer
than forecast. Things will begin to transition later today and more so
tonight with a wet forecast tomorrow and through Sunday night. At 9z
temperatures ranged from the middle 40s to lower 50s and we will likely only
see about another 5 degree drop for the morning lows.

For the entire forecast the main protagonists will be a cutoff low
currently over the Baja California and a persistent l/west trough pattern over the
eastern Continental U.S.. the first 60 hours of the forecast will be dominated by the
effects of a strong northern stream short wave that has dropped out of
British Columbia...Canada and into the Big Sky country. This short wave will continue to
dive southeast into the Central Plains and middle MS valley and upper portions
of the lower MS valley by Sun night. This will lead to Lee side
cyclogenesis tonight with the surface low deepening as it moves east
across the Central Plains and into the Ohio River valley Sun night while
driving a cold front twrds our area Sun night. At the same time a
piece of energy will break off of the Baja California low and move into the
lower MS valley sun. The combined impacts of the northern stream short wave and
southern stream disturbance will lower hghts some 7 dm late tonight and
through the day sun. Moisture will start to increase later today as
we move under weak SW flow in the middle and upper levels and ll flow
veers around to the southeast. Precipitable waters will increase from a paltry 0.28 (last
nights sndg) to around 1.25 inches overnight tonight.

First shot of rain showers may occur during the early morning hours sun and
through midday over the southeastern half of the County Warning Area. This activity will be
associated with the southern stream disturbance along with an 850 mb Theta-E
axis that will slowly move across this region. Have tried to show
this in the grids with best rain chances across the southeastern portions of
the County Warning Area early but as we move into the afternoon rain will likely taper
off some for the southern half and start to increase across our extreme
northwest especially late in the afternoon and early in the evening. This will be
in response to the effects of the northern stream short wave and approaching
cold front. In addition a few embedded thunderstorms and rain will be possible Sun
afternoon/evening as there will be a little instability to work with.

Rain will begin to come to an end after midnight Sun night as the
cold front starts to push into the region. Much colder and drier air
will work into the area Monday with a fairly chilly day in store Monday.
H925 temperatures drop to around -1c to 3c across the County Warning Area and this would
yield highs only getting into the middle/upper 40s to middle 50s across
the region. There should be a little of a breeze and this could help
keeps things mixed leading to highs a tad cooler than what gui is
currently advertising and have nudged things a degree or two lower.

Long term...overall the medium range models appear to be a little
more in line but the Euro is the slower model again when compared to
the 12z runs...and this is at odds with the 00z run last night where
it was the faster. The GFS has by far been the more consistent model
but the Euro is not drastically differnt so a blend of the two with
a continued slight lean twrds the GFS appears to be the better solution
here. The GFS does have support from the Gem and the gfes.

A quiet and cold night will be store Monday night as the surface high moves
right over the region. Clear skies...dry air...and rather light
winds should set the stage for decent rad cooling conditions and we
could see a light freeze for much of the northern half of the County Warning Area by Tuesday
morning. The one fly in the ointment for morning lows Tuesday will be how
much rain we receive sun and Sun night and the resulting ground
moisture left in place. After that things will quickly change. The
surface high will shift east with return flow setting up. The Baja California low
which by late Monday would have dug twrds the southern portions of the Baja California
will finally begin to lift out across Mexico and into southern Texas late
Tuesday night. A surface low will develop over the northwestern Gulf at the same
time and traverse across the northern Gulf Wednesday and twrds Florida Thursday. The old
Baja California low will continue to weaken and open up as it moves into the
lower MS valley Wednesday and Wednesday night. This will lead to high rain
chances Wednesday and into early Thursday. Light rain showers could begin as early as
Tuesday afternoon but likely hold off for the most part until Tuesday night.

Temperatures will be below normal through the forecast but outside of Tuesday
morning they will not be significantly below normal. /Cab/


VFR conditions will prevail through at least 06z Sunday at all
terminals. Clouds will continue to increase throughout the period
with conditions slowly deteriorating overnight Saturday into Sunday


Small craft exercise caution remains in affect until 6am over the
open waters. Winds may briefly slack during the daytime hours today
before increasing back to 15 to 20 overnight tonight. Unsettled
conditions will prevail from Sunday night forward with strong
northerly winds behind the cold front Sunday night into Monday.
Small craft advisories possible over all marine locations late
Sunday into Monday. Surface high pressure will build in Tuesday
allowing winds and waves to decrease. High pressure will quickly
slide east on Wednesday as surface low tracks along the northern Gulf
Coast. A stronger easterly flow will resume as a result on

Decision support...
Activities...slurry support
Small Craft Advisory this morning

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 to high risk severe
and/or direct tropical threats; events of National


Preliminary point temps/pops...
mcb 61 50 68 40 / 0 30 70 60
btr 62 51 70 42 / 0 30 60 50
asd 61 52 71 45 / 0 20 60 50
msy 62 56 73 48 / 0 20 60 50
gpt 59 51 68 45 / 0 20 60 50
pql 60 49 69 46 / 0 10 70 50


Lix watches/warnings/advisories...


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