Scientific Forecaster Discussion
fxus64 klix 250851
Area forecast discussion
National Weather Service New Orleans la
351 am CDT sun Jun 25 2017
some weak filtering of lower dp temps have moved into the area
by later yesterday evening. This has helped bring dp temps from
around 80 to the lower 70s. It's noticeable but not as noticeable
as it will be later today through Tuesday. Lower dp temps will
continue to slowly filter through the area today with the best
surge starting late this morning over southern Mississippi and
southward from there through the day. The dry air advection will
do a few good things. It will cause convective temps to rise and
precip water values to fall below 2" for the first time in a
while. This will be observed today by the decay and decrease in
coverage of sh/ts which will start during the late morning from
the north. So basically, we will start out with conditions that
are familiar; then observe greatly improving conditions through
the day from north to south.
Taking into account the above improvements, a Flood Watch should
not be needed. The only area that would raise some concern would
be along and west of the miss river from Baton Rouge to Thibodaux.
Some of this area could see another 1 to 2 inches of rainfall
this afternoon. But this could be the Atchafalaya contribution.
If this falls over the eastern Atchafalaya basin west of the
levees, it would be in the swamp system and no issues. If east of
the Atchafalaya levees then this rain would be falling on
saturated ground with population. Since these sh/ts would have
little motion, any quick 1 to 2" amounts could cause some minor
flooding. At the moment, we expect this to be mainly over the
eastern Atchafalaya basin with some east of the levee system. But
this is very thinly sliced which is the reason it is being
As the dry air moves through the area and approaches ongoing
convection, it will cause larger values of cin(convective
inhibition) via dry air entrainment producing evaporational
cooling and negative buoyancy which will cause any sh/ts to fall
rapidly. This could lead to some gusty conditions(30-40mph) near
Wednesday will show another deep surge of moisture moving back
into the area helping produce daily sh/ts once again. Although,
this time they should not be as abundant as recent coverage. A
more normal Summer pattern looks to evolve through the end of next
week with hit and miss sh/ts coverage, sea breezes and nocturnal
sh/ts development near shore. But also warm and muggy, but then
again it is Summer in the south.
Conditions currently VFR with the exception of btr, where light fog
is producing MVFR visibilities. It should be noted, however, that
some non-taf locations such as gao and aps are reporting occasional
IFR to LIFR visibilities in fog. Do anticipate that MVFR ceilings
will develop over the next couple of hours at many terminals, with
IFR not out of the question briefly around sunrise.
Should see improvement to VFR ceilings by mid-morning. Scattered
convection should develop as convective temperatures are reached by
late morning. Will carry thunderstorms in the vicinity in terminals. Best chances to avoid
convection would be at mcb as drier air filters in that area first.
Convection will diminish with sunset. VFR conditions will be the
prevailing condition for much of the overnight hours tonight, but
could see some visibility restrictions late as fog is possible with
all of the moisture remaining on the surface. 35
winds are expected to remain light today before becoming
northeast around 15kt late tonight into Monday as a cold front
should edge into the northern Gulf. The front will stall near the
coast in a Port Fourchon to Southwest Pass orientation keeping
sh/ts chances for most coastal waters through the period. The best
improvement in sh/ts conditions should be found east of the miss
river starting tonight through Tuesday morning. The front, or what
is left of it, will then be forced northward as southerly fetch
will once again envelop all the coastal waters.
Dss code: blue.
Activities: monitoring Hydro/convective trends
Decision support services (dss) code legend
green = no weather impacts that require action.
Blue = long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = heightened impacts with short-fused watch, warning or
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 of severe and/or
direct tropical threats; events of National significance.
Preliminary point temps/pops...
mcb 84 67 85 67 / 40 20 10 0
btr 85 70 85 69 / 50 20 10 0
asd 85 71 85 69 / 50 20 20 10
msy 85 74 83 72 / 50 30 20 10
gpt 85 72 84 71 / 50 20 20 10
pql 85 71 84 69 / 50 20 20 10