Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New Orleans la
813 PM CDT Thursday Sep 3 2015
The sounding this evening continues to depict a moist atmosphere
with some instability present. Precipitable water is above average at 2.09 inches.
Not much precipitation is expected across land overnight. Winds are
southerly at the surface then easterly to 600 mb and generally become
Previous discussion... /issued 347 PM CDT Thursday Sep 3 2015/
Short term...weak upper level inverted trough over the
southeastern Continental U.S. Continues to be the focus for shower and
thunderstorm development while developing ridge to the west
keeping things drier. Local radar currently shows scattered
convection over sela and southern Mississippi with generally
outflow driven movement. Offshore waters were nearly encompassed
by a swath of light to moderate rainfall. This activity has been
on a downward trend and will continue to do so for the next few
hours until its dissipated. The same in general is expected
inland with some lingering convection between 00z and 06z. Beyond
06z...mesoscale and medium range models suggest new sh/ts development
offshore south of la. Have kept probability of precipitation offshore higher overnight to
account for this.
Long term... upper level high developing over Texas and Oklahoma
will generally remain in place for a couple days before retreating
southwest early next week. This positioning will keep the County Warning Area on the
outer fringes of this ridge and still under influences of weak
troughing to the east. So thinking daily coverage in the 20 to 40
percent range can be expected through possibly the middle of next
scattered convection producing brief MVFR conditions.
Areal coverage is fairly small near terminals and using thunderstorms in the vicinity for
most terminals. May be able to remove thunderstorms in the vicinity before the 00z taf
package at most locations.
Overnight should see mainly VFR conditions...with potential for MVFR
visibilities at khum. Should start seeing at least isolated
convective development around 16z on Friday...similar to today.
Marine... a deep tropical moisture axis will remain over the Gulf
from near the Yucatan northward to the north central Gulf Coast.
This weakness will keep higher chances of ts activity in the coastal
waters through the forecast. Winds and seas will be higher near
scattered ts. Wind gusts could be as high as 30 knots with the
strongest activity. Outside ts activity conditions will remain
rather benign with a weak pressure gradient. Nocturnal activity will
be the most abundant while there will be a general decrease in
activity during the late morning through late afternoon hours.
Decision support services (dss) code legend
green = no weather impacts that require action
blue = long fused watch/warning/advisory in effect or high
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 risk severe and/or direct
tropical threats; events of National significance
Preliminary point temps/pops...
mcb 71 92 72 93 / 30 30 10 30
btr 73 91 73 93 / 30 30 10 30
asd 74 90 74 92 / 30 40 20 30
msy 77 89 76 91 / 30 40 20 30
gpt 77 89 76 91 / 30 40 20 30
pql 74 90 74 91 / 30 40 20 30