Scientific Forecaster Discussion
fxus64 klch 201206
Area forecast discussion
National Weather Service Lake Charles la
706 am CDT Wed Jun 20 2018
storm system over deep south Texas continues to spin this am W/
storms/shwrs movg onshore FM south Texas around to south central
Louisiana. This pattern will cont thru the day tdy. Ceilings and
vsby will be lwr in and near storm actvty.
Previous discussion... /issued 413 am CDT Wed Jun 20 2018/
precipitation being observed on radar this morning is noticeably
more sparse in nature than it was this time yesterday. Still, with
deep tropical moisture in place (forecast precipitable water values of 2.2 to
2.3) the combination of the southward drifting tropical wave that
has brought the widespread rain over the past couple of days and
an eastward advancing upper trough over the central U.S. Will be
more than enough to initialize another day of numerous showers and
a few thunderstorms.
Went ahead and extended the Flash Flood Watch until 00z this
evening for Jefferson and Orange counties and added southern
Jasper and Newton counties as well as Calcasieu and western
Cameron. Based this on the expected quantitative precipitation forecast totals through the day and
the rfc's flash flood guidance. The official forecast calls for 1
to 2 inches of rain across these areas, but with banding expected
to develop somewhere over this area again today, 3 to 4 inches
will certainly be possible in some spots. Meanwhile, taking the
previous rainfall into consideration, the rfc's flash flood
guidance is presently showing 6 hourly quantitative precipitation forecast thresholds of between
1 and 3 inches. As was mentioned in the watch product, the
addition of Calcasieu Parish was in order to include the western
half of the Parish, including Vinton, where significant rainfall
fell yesterday. 6 hourly quantitative precipitation forecast thresholds in this area are around 2
inches. The flash flood threat across the eastern half of the
Parish is much lower with quantitative precipitation forecast thresholds in the 4+ inch range.
By tonight, the influence of systems over the region will shift
from the tropical wave drifting south into Mexico to the
aforementioned upper trough deepening over the central U.S. The
end result will be about the same with this trough lifting the
continued deep layer moisture over the area to produce numerous
showers and thunderstorms again on Thursday. At this point it
appears that the axis of most widespread precipitation will shift
further east into southwest Louisiana. The Silver lining is that
as the trough slides east, it will take much of the mid and upper
level moisture with it bringing the precip to an abrupt end
The combination of drier air aloft and high pressure building in
across the eastern Gulf will make for a dry end of the week and
weekend allowing some of the hardest hit areas to dry out. A more
typical summertime pattern will return by early next week with
scattered afternoon thunderstorms each day beginning Monday.
winds and seas will remain elevated this morning between high
pressure extending through the southeast Continental U.S. And adjacent Gulf
waters, and low pressure over East Texas. Winds and seas gradually
weaken through the day as the northwest Gulf pressure gradient
continues to relax with a weakening of the East Texas trof.
Scattered showers and a few thunderstorms will continue today and
tomorrow before coming to an end Friday.
Preliminary point temps/pops...
aex 87 73 86 73 / 60 60 80 20
lch 86 77 86 76 / 70 60 60 20
lft 88 76 87 75 / 40 40 50 20
bpt 84 76 86 76 / 70 70 50 20
la...Flash Flood Watch through this evening for laz041-073.
Texas...Flash Flood Watch through this evening for txz215-216-261-262.
GM...Small Craft Advisory until 7 am CDT this morning for gmz470.
Small craft exercise caution through this evening for gmz470.
Small craft exercise caution through this evening for gmz472.
Small craft exercise caution until 1 PM CDT this afternoon for