Scientific Forecaster Discussion

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Area forecast discussion...updated 
National Weather Service New Orleans la
836 am CDT Wednesday Apr 23 2014

Short term...
reminder that Wednesday is weekly radio test day around 11 am this

Long term...
the next severe weather potential statement issuance will introduce a chance of strong to
possibly severe thunderstorms for early next week...based on
latest model trends and Storm Prediction Center 4-7 day outlook. No other changes at
this time.


Sounding discussion...
no issues with flight this morning. An overly dry sounding above
810 mb with just some moderate saturation with 5c depressions from
surface inversion to base of subsidence inversion at 810 mb. Quite
stable with a showalter of 6...lifted index 0.6. Precipitable
water 0.79 inches is about one-half inch less than previous 12
hours. Winds calm to light NE surface to 5kft...northwest 5-15 knots to
17kft...a layer of SW 10 knots to about 22kft...then northwest 10-55 knots
above. Peak wind 280/55kt at 50.2kft. Double tropopause structure
with a warm -58.2c at 200mb...then -71.9c at 106mb. Balloon burst
28 miles east-southeast at an altitude of 32625 M/ 20.27 miles up in the
Mississippi Sound about 6 miles S of Buccaneer State Park on the
Hancock County coast. 24/rr


Previous discussion... /issued 700 am CDT Wednesday Apr 23 2014/

latest surface analysis showed a deep 994mb low over Maine with a
cold front extending south to Georgia to Florida Panhandle to
Mississippi Delta mouth to southwest Louisiana. Dewpoint readings
were 65 to 70 south of the front 55 to 65 north of the front.
Patchy dense fog was present along and immediately north of the
front...Houma Airport was quarter mile...galiano Airport was a
quarter...Patterson was half. cams around Houma
indicated visibility restrictions above 2 miles. Will handle fog with
Special Weather Statement for patchy dense fog this morning. Water vapor imagery showed
drying in middle and upper atmosphere over the Gulf Coast due to northwest
flow over the Gulf Coast. Upper air charts showed a ridge axis
over the plains and a trough axis from Washington to Arizona. 18

Short term...
weather systems are expected to continue their progression from
west to east. Frontal boundary of the south half of the forecast
area is expected to dissipate today. Upper level trough axis over
The Rockies will track east to the plains and deepen the surface
trough/front over the plains today. This feature will allow surf winds
to become southerly from the central Gulf Coast to the middle
Mississippi Valley by late tonight. Low level moisture will
slightly increase. Mostly clear skies and radiational cooling to
saturation is likely Thursday and Friday mornings. With this
said...the forecast will remain dry today and Thursday. 18

Long term...
upper level trough over the Great Basin will track east. With the
axis already negatively tilted and northern track equate to low to
none chances of rain as the axis approaches the forecast area
Friday through Saturday across the north half. The next system
will take a farther south track across rockies over the weekend.
Moisture axis will approach the northwest zones Sunday night and
over the forecast area Monday. Will maintain rain chance and
possibly strong convection. Albeit weak south flow at times over
the weekend...instability with cape around 1500 j/kg in place on
Monday before the axis and surface front sweep through early
Tuesday according to GFS and European model (ecmwf). Both show an evolution of the
trough into a deep closed low over Central Plains late Monday then
they diverge after Tuesday. GFS keeps the low over the middle south
through Tuesday then move southeast along the I-20 corridor this
track will bring a cloudy sky...below norm Wednesday and Thursday
and a chance of cold rain across the north zones the Continental U.S.. European model (ecmwf)
keeps a closed low but farther north. We lean to GFS with temperatures
but not as cold and just cloudy and no rain for now after the
frontal passage. 18

patchy fog has begun to develop and will result in IFR to MVFR
conditions this morning at several airports...especially from
08-13z. The lowest conditions are likely at khum where visibility
restrictions are currently the lowest. Otherwise...VFR conditions
will prevail through this evening.


fairly benign conditions expected over the coastal waters from now
through middle weekend. High pressure currently centered over the
central Gulf of Mexico will gradually shift eastward. Southerly
winds will generally be around 10 knots with seas 2 feet or less.
Going into Sunday and beyond the winds/seas will increase as the
pressure gradient tightens due to surface low developing in the
Southern Plains. Exercise caution conditions could exist as early as
Sunday afternoon and persist through Monday. Models indicate that a
cold front will swing through Tuesday. It remains to be seen how
strong this boundary is.


Decision support...
Activities...slurry support
monitoring river flooding

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 82 58 83 62 / 10 10 10 10
btr 84 61 84 64 / 10 10 10 10
asd 81 60 81 61 / 10 10 10 10
msy 79 64 80 65 / 10 10 10 10
gpt 79 58 78 61 / 10 10 10 10
pql 79 57 80 63 / 10 10 10 10


Lix watches/warnings/advisories...