Area forecast discussion
National Weather Service New Orleans la
815 PM CDT Thursday may 23 2013
Sounding discussion...
no problems with launch this evening. Rather typical dry adiabatic
sounding for northwest flow regime currently in place. Somewhat
dry with very little in the way of moist layers as the wettest
level is a 4 degree spread at 916 mb / 2800 feet but departs quickly
above. Precipitable water 1.26 inches but surface based positive
area is 3561 j/kg with low helicity of only 21 m2/s2. Storm motion
353/8 knots looks well aligned with radar trends. Winds were SW 5 kts
surface to about 1800 feet...veering northwest-north 5-15 knots to 15kft...then
backing to northwest 20-70 knots through tropopause and lower stratosphere.
Peak wind 285/70 knots at 41.3kft. Balloon over-achieved by reaching
a rare 6.4 mb...34.112 km / 111916 feet / 21.2 Michigan and burst 25 miles
southeast of launch over Upper Lake borgne about 1 mile west of
the upper tip of Biloxi marsh...but not before reaching Waveland
MS prior to westward drift on easterly winds in upper
stratosphere. 24/rr
&&
Previous discussion... /issued 318 PM CDT Thursday may 23 2013/
Discussion...
A few isolated thunderstorms are still possible over the next few
hours as we reach peak heating. Most of the activity is expected
across the coastal parishes. This activity is expected to subside
early this evening. However...an approaching backdoor wedge
front will begin to move from the northeast after midnight
tonight. Given the high amount of low level moisture in place...we
could still see a few isolated pockets of convection along the
front. The front is expected to exit the South Shore by Friday
afternoon giving way to drier conditions as a ridge of high
pressure moves in.
A very pleasant weekend is on tap with the lower dewpoints in
place. Some of the extreme northern zones could see temperatures
drop into the upper 50s Saturday night. However...conditions will
begin to change early next week as southerly flow returns.
Moisture should be deep enough by the latter half of next week to
support afternoon convection. Even then...coverage will remain
isolated.
7/arm
Aviation...
VFR conditions will prevail at most airports through this evening.
Isolated rain showers/thunderstorms and rain this afternoon and evening will have to be
monitored for later inclusion in tafs...but probability is too low
for mention at this time. Slightly drier air in the low levels
will start to filter in from north to south across kmcb area late
tonight...and areas along I-12/10 around midday to the afternoon
hours on Friday. Areas of light to moderate fog and low ceilings in
stratus will again be possible late tonight through middle morning
Friday at some airports. 22/dew point
Marine...
Ridge of high pressure is expected to build over the coastal
waters on Friday. A drier airmass in place will produce a steady
northeast breeze...especially late Friday night into Saturday
morning. Small craft caution conditions are likely...mainly along
the sounds.
Winds are expected to shift slowly to the southeast in time for
early next week. This flow is expected to be prevailing for much
of next week. As a result...higher swells are expected by weeks
end due to the long fetch.
Decision support...
Dss code...blue.
Deployed...none.
Activation...none.
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
significance
&&
Preliminary point temps/pops...
mcb 65 86 56 85 / 20 10 0 0
btr 69 89 64 87 / 20 20 10 0
asd 68 88 60 84 / 20 10 0 0
msy 71 88 68 85 / 20 20 10 0
gpt 69 89 61 83 / 20 10 0 0
pql 67 88 57 84 / 20 10 0 0
&&
Lix watches/warnings/advisories...
la...none.
GM...none.
MS...none.
GM...none.
&&
$$
