Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New Orleans la
320 am CDT Wednesday Aug 20 2014
Short term...just like the previous night it was another quiet yet
warm one. No convection was noted on the scope through much of the
night. The biggest difference tonight from last night was temperatures.
Morning lows may be quite similar but temperatures did drop much faster
during the evening hours with much of the region in the middle 70s by 7z.
The exceptions are along the coast where temperatures were still mostly in
the lower 80s.
Through the remainder of the work week the models are in very good
agreement. The middle level ridge will strengthen as expected and by Friday
a 594dm ridge will be centered over the lower MS valley. As mentioned
in the last few forecast this will lead to lower probability of precipitation and warmer
temperatures...and most likely the warmest temperatures we have seen so far this
season. First for thunderstorms and rain chances...the ridge will provide subsidence
while warming low and middle levels will lead to a cap. All of this will
have negative impacts on convection. That said cant rule out isolated
to widely scattered rain showers and thunderstorms and rain especially along the sela coast where
seabreeze interactions combine with peak heating in the afternoon
possibly leading to convection. As for temperatures nothing has changed in
that respect and it still looks to be hot especially Thursday and Friday.
H925 temperatures could approach 28-29c and this would lead to upper 90s on
those days. As for any possibilities of a heat advection it looks like we
will remain just under criteria. Morning lows should cool off in
most places to allow for some relief. The exceptions will be in the
city where lows could struggle to get out of the upper 70s. Afternoon
heat indicies will approach the middle 100s. So with that said it will
still be quite warm and oppressive in the afternoon. /Cab/
Long term...medium range models are in good agreement through the
weekend and to begin next week. The models diverge as we get into the
middle portions of next week but this falls out of the forecast period.
Trough the weekend and Monday next week the ridge will still dominate
the region leading to continued hot and mostly dry conditions. As we
head into Monday night and Tuesday the ridge will begin to shift far enough
to the northeast allowing weak erlys to increase rain chances.
As for the tropics...NHC continues to monitor an area of low
pressure east of the Windward Islands with a 50 percent chance of
developing into a tropical cyclone over the next 5 days as it moves
into the Caribbean. Models differ significantly on eventual track of
this system and with nothing even developed yet it is futile to try
to forecast where this possible system will go. As always in middle
Aug...its hurricane season and no matter what you should pay
attention to the tropics. Updates will be made as necessary if there
is any change. /Cab/
VFR conditions will prevail through the period outside of
convection. Rain chances remain low but scattered showers and storms
will develop. Not including in tafs this forecast period but rather do
an update as needed. Otherwise... expect light southwest winds
generally less than 10 knots and partly cloudy skies with cloud
bases around 4kft during the day.
surface ridge is currently centered in the eastern Gulf of Mexico
which is keeping winds in a steady SW direction. This high pressure
will gradually shift to the northern Gulf Coast over the next couple
days. This will cause winds to relax and become more variable in
direction. Seas will respond to this wind reduction and fall to 2
feet or less areawide.
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 to high risk severe
and/or direct tropical threats; events of National
Preliminary point temps/pops...
mcb 95 74 96 74 / 20 20 20 10
btr 96 76 96 76 / 30 20 20 10
asd 94 77 93 77 / 20 10 20 10
msy 94 78 94 78 / 40 20 20 10
gpt 93 78 93 78 / 20 10 20 10
pql 93 77 94 76 / 20 20 10 10