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Area forecast discussion 
National Weather Service New Orleans la
347 am CDT Sat Jul 12 2014

Short term...

A weak middle to upper level ridge axis will build over the area
today and remain in place through tomorrow. This ridge axis will
produce an elevated mixed layer from around 700mb on up through
the remainder of the atmospheric column. Weaker lapse rates will
result from this mixed layer aloft due to the combination of drier
air and slightly warmer temperatures taking hold. With these
weaker lapse rates in place...overall instability will
decrease...with cape values only ranging from 500-1500 j/kg.
Additionally...precipitable water values will decrease to around
1.5 to 1.75 inches during the weekend. There will still be
scattered convection developing during peak heating hours when the
convective temperature is reached...but the overall coverage will
be lower than seen the last few days. Have kept in chance probability of precipitation for
much of the area...with only slight chance probability of precipitation in place for the
northern third of the forecast area. This is mainly due to an
expected lack of low level boundaries and resultant convergence in
this area. Closer to the coast...seabreeze and lakebreeze
boundaries should provide enough low level forcing to initiate
convection. With a bit less cloud cover and a bit more subsidence
in place...temperatures will rise into the middle 90s across much
of the area each day.

Conditions will begin to turn more unsettled on Monday...as the
upper level ridge begins to break down...and some Gulf moisture
surges back into the area. Precipitable water values should rise
back to near 2 inches by Monday afternoon. Lapse rates will also
begin to strengthen aloft as the ridge weakens...and expect to see
cape values increase to between 1500 and 2500 j/kg. Given these
conditions...have increased probability of precipitation back into the change range of
30-40 percent for the entire forecast area Monday afternoon.

Long term...

The models are still in good agreement that a strong upper level
trough will sweep through the Great Lakes states and into the
northeastern Continental U.S. On Tuesday. As this trough axis slides through
the area...a potent cold front will approach from the north. This
front will likely stall over the forecast area Tuesday night and
linger through the remainder of the week as the parent trough axis
pulls to the north and east. A secondary upper level trough and
reinforcing frontal boundary will then slip into the Gulf south on
Thursday and linger into the weekend. These fronts will serve as
a focus for convection each day...with the convection being
diurnally driven. As a result...have kept in high end chance probability of precipitation
for each day beginning on Tuesday and persisting through Saturday.
During the overnight hours...keep low end chance probability of precipitation in
place...but expect to see the majority of the convection during
the early evening hours. As daytime heating and overall
instability wanes...convection coverage will tend to reach a
minimum during the late evening and overnight hours each night.
There will be the potential for some strong to possibly severe
thunderstorm activity from Monday through the end of the week.
Strong downburst winds will be the main threat as model soundings
show a pool of drier air in the mid-levels. This dry air in the
middle-levels could entrain into the downdraft and produce strong
straight line wind events. The high precipitable water values of around 2 inches
and fairly slow movement of the storms could also bring street
flooding issues to a few areas.

&&

Aviation...
residual moisture and a more Continental trajectory has induced some
LIFR ceilings and visibility at a few locations that should improve quickly
after about 1230z. VFR conditions are expected all terminals after
13z with considerably less convective coverage today to only warrant
prob30 groups. 24/rr

&&

Marine...
high pressure along the Gulf Coast will maintain light winds and low
seas today and Sunday. Bermuda ridge becomes more steady state by
Monday for a more moderate onshore flow that carries into Tuesday.
Models are beginning to back off on southward progression of strong
cold front which may still reach the coast induced by pre-frontal
convection. This scenario will briefly relax the winds for Wednesday
prior to Bermuda ridge become re-established later in the week.
Despite fluctuations in wind direction and speed...seas should
typically remain below 2 feet for much of the forecast period...with
exceptions for brief localized roughness near convection. 24/rr

&&

Decision support...
dss code...green.
Deployed...none.
Activation...none.
Activities...slurry 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 to high risk severe
and/or direct tropical threats; events of National
significance.
&&

Preliminary point temps/pops...
mcb 93 70 93 70 / 20 10 20 10
btr 94 72 94 71 / 30 20 30 20
asd 92 72 92 72 / 30 20 30 20
msy 91 73 91 73 / 30 20 30 20
gpt 93 75 93 75 / 30 20 30 20
pql 91 70 90 71 / 30 20 30 20

&&

Lix watches/warnings/advisories...
la...none.
GM...none.
MS...none.
GM...none.
&&

$$

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