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Area forecast discussion 
National Weather Service New Orleans la
657 am CST Sat Dec 27 2014

..sounding discussion...

Atmosphere is really starting to juice up this morning with an
almost 9000 foot saturated layer in the low-levels. Precipitable
water value has climb to just over 1.5 inches...which is double the
normal value for this late in the year. This is also over a one
inch increase compared to yesterday morning/S precipitable water. Also
impressive is that the surface temperature is over 13 degrees
celsius higher /warmer/ than this time yesterday. Temperatures in
most of the rest of the column are only a few degrees different
from yesterday morning. Not much for instability at this time with
a lifted index of +3.1 and no surface or mixed layer cape so
thunder will be limited today. A veering wind profile was found
with southeast winds near the surface. Above 5500 feet...a deep
layer of winds from the southwest was found...which will keep
pumping moisture into the central Gulf Coast. A peak wind speed of
93 knots was located at 39500 feet.

12z balloon info: no issues with the flight this morning. The
balloon burst over Delaware Soto National Forest 73 miles downrange
from the office at a height of 20.3 miles above the ground. The
flight lasted 100 minutes.

Ansorge

&&

Previous discussion... /issued 437 am CST Sat Dec 27 2014/

Short term...

Flood Watch remains in effect for the region through 00z Monday.

Heavy rainfall potential for southeast Louisiana answer southern
Mississippi from Saturday though Sunday evening. Looks like the
bulk of the heaviest precipitation will occur between late Saturday
afternoon and early Sunday morning. Forecast soundings showing
around 2 inches of precipitable water during the Saturday afternoon through
Saturday night time frame...which is about a 2.5 Standard
deviation for late December. Southwesterly flow will continue to
draw deep moisture until the region along with a weak surface
boundary over the region. Divergence aloft will also increase
throughout the day today. With that in mind the potential for very
heavy rainfall possible and localized flooding to be expected.

In addition to area-wide widespread heavy rainfall...increased
instability and divergence aloft create the potential for scattered and
embedded thunderstorms bringing localized heavier rainfall amounts
to certain areas with most of the activity being elevated.

.Rainfall amounts and impacts from this weekends event...

Rainfall amounts expected to be in the 2 to 5 inch range with
local amounts of up to 10 inches possible...where training of
heavier bands of heavy showers and embedded thunderstorms take
place. Most of the heaviest rainfall is expected to fall between
Saturday afternoon and Saturday night. A break in the activity is
possible after daybreak Sunday through Sunday afternoon before an
approaching cold front moves into the area. Expect to see up to an
additional inch with the second round ahead of the front on Sunday
afternoon and evening. Impacts of concern are street flooding and
the potential for faster response rivers and streams to rise above
flood stage.

Long term...

Cooler and drier conditions expected to persist from Monday
through at least middle week. Temperatures will remain slightly below
normal through early week with a secondary push of cooler air by
middle week as a 1031 mb high Parks itself over the southern plain
states. Lowered probability of precipitation for New Years Day as both the Euro and the
GFS have backed off on probability of precipitation for the region. The next significant
chance of rain expected as the Post new years weekend approaches later
next Friday and beyond.

Aviation...

Although somewhat delayed...steady deterioration of conditions to
IFR ceilings and visibility is expected as rain becomes increases towards
daybreak. It will be difficult to show much improvement through 06z
Sunday as large scale lift will maintain heavy rainfall and low
ceilings as predominant conditions next 24-30 hours. 35

Marine...

Will leave Small Craft Advisory in place through 15z...at which time
it will likely be replaced with exercise caution headlines on the
middle morning update. As gradient relaxes slightly...anticipate winds
will drop below 15 knots by middle afternoon. Cold front finally pushes
through coastal waters on Monday...but cold advection does not
appear strong at this time. Another southern stream low pressure
system will affect the area toward the end of next week...beyond the
scope of this forecast package. 35

Decision support...

Dss code...blue.
Deployed...none.
Activation...none.
Activities...slurry support
assessing Flood Watch potential for the weekend

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 69 61 63 44 / 100 90 70 60
btr 74 62 64 45 / 100 100 70 50
asd 71 62 71 49 / 100 90 50 60
msy 74 63 71 52 / 100 90 50 50
gpt 68 62 72 51 / 100 90 50 60
pql 69 59 74 50 / 100 90 50 60

&&

Lix watches/warnings/advisories...
la...Flood Watch until 6 PM Sunday for the following zones:
Ascension...Assumption...East Baton Rouge...East
Feliciana...Iberville...Livingston...lower
Jefferson...lower Lafourche...lower Plaquemines...lower St.
Bernard...lower Terrebonne...northern
Tangipahoa...Orleans...Pointe Coupee...southern
Tangipahoa...St. Charles...St. Helena...St. James...St.
John The Baptist...St. Tammany...upper Jefferson...upper
Lafourche...upper Plaquemines...upper St. Bernard...upper
Terrebonne...Washington...West Baton Rouge...and West
Feliciana.

GM...Small Craft Advisory until 9 am Saturday for the following
zones: coastal waters from Boothville la to the Southwest
Pass of the Mississippi River out 20 nm...coastal waters
from Pascagoula MS to Stake Island la from 20 to 60
nm...coastal waters from Port Fourchon to lower Atchafalaya
River from 20 to 60 nm...coastal waters from Port Fourchon
to lower Atchafalaya River out 20 nm...coastal waters from
Stake Island la to the Southwest Pass of the Mississippi
River from 20 to 60 nm...coastal waters from the Southwest
Pass of the Mississippi River to Port Fourchon from 20 to
60 nm...and coastal waters from the Southwest Pass of the
Mississippi River to Port Fourchon out 20 nm.

MS...Flood Watch until 6 PM Sunday for the following zones:
Amite...Hancock...Harrison...Jackson...Pearl
River...Pike...Walthall...and Wilkinson.

GM...Small Craft Advisory until 9 am Saturday for the following
zones: coastal waters from Boothville la to the Southwest
Pass of the Mississippi River out 20 nm...coastal waters
from Pascagoula MS to Stake Island la from 20 to 60
nm...coastal waters from Port Fourchon to lower Atchafalaya
River from 20 to 60 nm...coastal waters from Port Fourchon
to lower Atchafalaya River out 20 nm...coastal waters from
Stake Island la to the Southwest Pass of the Mississippi
River from 20 to 60 nm...coastal waters from the Southwest
Pass of the Mississippi River to Port Fourchon from 20 to
60 nm...and coastal waters from the Southwest Pass of the
Mississippi River to Port Fourchon out 20 nm.

&&

$$

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