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Area forecast discussion
National Weather Service New Orleans la
408 PM CST Thu Nov 21 2019

Short term...latest surface analysis showed a 1024mb high over
coastal South Carolina. Light southeast flow was present over the
forecast area and lower Mississippi Valley. In addition, a deep
surface low was located over the Great Lakes region with an
associated cold front extending southwest to Missouri to north
central Texas. Upper level analysis showed a vigorous cyclonic
low over southern Nevada with a moist southwest flow over New
Mexico and another moisture axis from south Texas to west

Southerly flow off the Gulf of Mexico will continue to advect in
some warmer air from the central Gulf, and this will maintain a
seasonal temps tonight and Friday. This flow will finally tap some
deeper moisture during the day on Friday. Upper level low will
push east with the trough axis through the mid Mississippi Valley
late Friday night but remain positively tilted. Surface base convective available potential energy
were running around 200 to 300 j/kg across the north half the
forecast area Friday night through Saturday noon with 0-3km
helicity between 200 to 270m/S with decreasing values farther
south. While no threat of severe weather is forecast, we can not
rule out a severe storm or two along the line of showers and
isolated storms pushing through this time frame.

The associated surface low will drag a strong cold front across
the Southern Plains states Friday. This front and an associated
upper level trough axis will sweep through the forecast area late
Friday night into Saturday morning. The front should sweep
through the area by mid-day Saturday, and high temperatures should
occur in the morning hours across the area. Cooler and drier air
should begin to quickly push into the area.

Long term...ridging will take hold on Sunday and remain in place
through Monday. A westerly flow aloft pattern will set up and
several disturbance will track across The Rockies next. GFS has
pulled the dynamics north and allowing a weaker push of the
associated cold front across the lower Mississippi next Tuesday
into Wednesday. As a result, front may push through but hang
around just south of the forecast area Wednesday through Friday.


Aviation...VFR conditions expected to prevail at all terminals with just a
steady increase in high based ceilings at cirrus levels during the
period. 18


Marine...with the surface high to the east, southeast flow will
become more pronounced by tonight into Friday. Low pressure
system develops over northeast Texas/northern Louisiana with
associated cold front that should push into the Gulf Saturday
morning. This will bring a round of pre-frontal convection that
may become a squall line in the coastal waters. Prior to
convection, temperatures and dewpoints will be rising through a
range of near shore water temperatures conducive for sea fog
formation or at least a low marine layer.At this time, it does
not appear winds get quite strong enough to warrant small craft
advisories, but should easily slot into the exercise caution range
through Sunday morning. 18


Decision support...

Dss code: blue.
Deployed: none.
Activation: none.
Activities: forecast support for city of New Orleans.

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; marginal risk severe or excessive rain.
Yellow = heightened impacts with short-fused watch, warning or
advisory issuances; radar support for slight risk severe or
excessive rain.
Orange = high impacts; enhanced risk severe; nearby tropical events;
hazmat or other large episodes.
Red = full engagement for moderate to high risk of severe and/or
excessive rainfall


Preliminary point temps/pops...
mcb 58 75 59 68 / 0 60 90 60
btr 61 77 60 67 / 10 60 90 50
asd 57 77 60 71 / 0 10 60 80
msy 62 76 63 70 / 0 10 60 70
gpt 58 73 61 70 / 0 10 30 70
pql 57 77 60 73 / 0 10 20 70


Lix watches/warnings/advisories...

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