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Area forecast discussion 
National Weather Service New Orleans la
436 PM CST Monday Dec 22 2014

Short term...
showers and a few thunderstorms are still possible late this
afternoon and into the evening hours as a warm front pushes
onshore. Temperatures and dewpoints feel more like Spring rather
than winter. As a southerner...generally when you get this kind of
feeling in December you know that some pretty strong storms could
be possible before your next cool down. This is the situation that
will unfold over the next 24 to 48 hours over the southeast.
Current analysis shows that the aforementioned warm front is already
bisecting the forecast area this afternoon as dewpoints are
currently in the middle to upper 60s along and south of Interstate
10/12. A few showers have been developing this afternoon in
advance of this warm front and we expect that trend to continue
this evening and overnight.

Tuesday still looks to be a pretty active day as the Storm
Prediction Center maintains a slight risk for severe weather over
the entire forecast area. A deepening low should begin to push
across the nation and with it should bring a cold front through
the region. With this warm moist air in place and a large scale
forcing expected to come through the region strong to severe
storms will be a concern...all modes of severe weather are
possible as this system moves through Tuesday. There are a few
things that could limit this threat however...instability still
looks to be somewhat conditional as clouds...fog..and possibly
ongoing convection could dampen the amount of instability that the
system has to work with. The jet dynamics and some of the other
severe weather parameters look pretty good. The shear is
there...the helicity is there...forcing will be here...but the
instability could be the limiting factor. The best combination of
all the parameters look to be along the coast and across the
eastern portions of the forecast area. The northern extent of the
possible severe weather depends on how far north the warm front
gets tonight and tomorrow before the cold front sweeps through.
It still remains to be seen how far north the warm sector will
extend...but given that we already have dewpoints in the middle to
upper 60s across portions of the forecast area...the warm sector
is already making a northward push. We will have to watch all of
these factors through the overnight hours and watch the evolution
of this system closely. Just remain weather aware tonight and
Tuesday and pay attention to the forecast as updates are made. 13/mh

Long term...
the front will mover through the area Tuesday night and The Heart
of the cold air will filter into the area on Wednesday ad
Wednesday night. Wednesday will be cooler in the 50s and Wednesday
night look for temperatures to dip into the 30s for Christmas
morning. The trough axis will finally begin to pull east of the area on
Thursday...with strong subsidence and very dry air taking hold of
the area. Sunny skies and cooler than normal temperatures can be
expected. Daytime highs will only climb into the middle to upper
50s and lows on Thursday night will drop back into the lower 40s
over inland locations as conditions radiate out. There are still
differences in the long range with the GFS and European model (ecmwf)...have not
made any significant changes to the forecast. Have continued with
a blend of model guidance. This continues to bring a chance of
rain to the area beginning Friday night and continuing into
Saturday and Saturday night as the trough axis and frontal
boundary move through the area. Will have to watch and see if
thunderstorms will need to be added to the forecast during this
time frame. 13/mh

&&

Aviation...
generally MVFR to IFR conditions will prevail through the period
with low clouds settling in after sunset. Warm front will move
northward late...with isolated to scattered showers and possibly a
few thunderstorms. Have included thunderstorms in the vicinity toward the end of the period
at all taf sites as thunderstorms become more likely. Squall line
will move through ahead of cold front Tuesday evening...with an
accompanying wind shift to the northwest and strong gusts possible.

&&

Marine...
winds should then begin to respond to synoptic scale frontal
system developing in the plains states with deeper fetch into the
Gulf to increase winds to low end Small Craft Advisory levels over
the next 24 hours. Have already put up exercise caution headlines
for portions of the coastal waters tonight as conditions are
expected to deteriorate overnight and tomorrow. A hard wind shift
still looks to be on track for late Tuesday night into Wednesday
morning as small craft conditions look to be on The Table during
this time frame. Squall line convection on the coastal waters
late Tuesday evening will likely prompt short- fused marine
warning issuances during that time- frame. Severe weather
potential should move east of MS coastal waters by daybreak
Wednesday.

&&

Decision support...
dss code...blue
deployed...none.
Activation...none.
Activities...slurry support
assessing severe weather threat for Tuesday

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 61 70 46 54 / 30 100 100 10
btr 62 72 47 55 / 30 100 100 10
asd 63 73 50 56 / 30 100 100 10
msy 63 74 51 56 / 30 100 100 10
gpt 63 72 53 58 / 30 100 100 20
pql 62 73 55 61 / 30 100 100 20

&&

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

$$

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