Scientific Forecaster Discussion
fxus64 klch 181128
Area forecast discussion
National Weather Service Lake Charles la
628 am CDT Fri Oct 18 2019
Aviation...VFR conditions are expected through the period,
however light patchy rain and ceilings at around 10kft will occur
this morning. Clouds will decrease through the period and winds
will north to northeast at 10kts or less.
Previous discussion... /issued 519 am CDT Fri Oct 18 2019/
latest upper air analysis/water vapor satellite imagery showed a
shortwave trof over coastal southeast TX, with an upstream western Continental U.S.
Trof axis stretching from the intermountain west to the desert
SW. At the sfc, a ridge of high pressure extended from the mid MS
River Valley into central Texas.
Not much has changed in model guidance this forecast cycle, and
thus, little overall changes were made to the forecast this
morning. Considerable mid and high level cloud cover blankets the
area this morning in association with the shortwave trof, with
some light returns and even an isolated shower or two showing up
on radar. Klch 00z radiosonde observation depicted a couple of very dry layers
below 7k ft, so it is unlikely that the light radar returns are
netting any precipitation at the surface. The shortwave trof is progged to
continue translating quickly eastward through the day, with clouds
eroding from west to east such that a clear sky is expected areawide by
this evening. Afternoon temperatures will be much warmer than
yesterday, though are still expected to stay below seasonal
Potential tropical cyclone 16, consisting of a generally broad
low over the west central Gulf with vigorous convection displaced
off to the east/NE, is progged to move quickly off to the NE and
become increasingly entangled with the aforementioned shortwave
trof. While some intensification/increase in organization is
expected later today as the system nears the north central and
northeast Gulf Coast, impacts to our area will be minimal, and
mostly relegated to elevated winds and seas over the Gulf waters
east of Intracoastal City.
Dry and cool weather is expected tonight in the wake of the
departing shortwave trof, with a warming trend set to ensue on Sat
as deep layer west/SW flow takes hold with the passage of the low
amplitude western Continental U.S. Trof axis. Continued warming into sun with low
end rain chances returning ahead of a more robust upper trof
digging into the central conus, with this feature progged to send
a frontal boundary through the area on Monday. Guidance converging on
frontal passage through the day on Mon, with bulk of rains having
ended by Monday evening. Widespread showers and thunderstorms to
precede and accompany the boundary, with at least a low end severe
risk given progged shear/buoyancy across parts of southwest and
east and south central la Monday afternoon. Not much in the way of
cooler air behind the front, but enough to knock temperatures back
below seasonal normals.
Dry weather with below normal temperatures will prevail Tuesday and
Wed, with uncertainty lingering Wednesday owing to how quickly moisture can
return. Continued with low end chance pops, increasing to mid/high
chance Thursday night into Friday with good global model agreement on
another frontal passage during this time period.
a moderate offshore flow will persist into tonight as potential
tropical cyclone sixteen tracks northeast across the central Gulf
of Mexico. An onshore flow will resume late Saturday into Sunday,
becoming modest Sunday night into Monday ahead of an approaching
cold front forecast to push through the area Monday afternoon and
evening. Scattered to numerous showers and thunderstorms are
expected with the frontal passage, with a brisk offshore flow
developing in its wake.
Preliminary point temps/pops...
aex 75 53 83 63 / 0 0 0 10
lch 76 58 84 69 / 0 0 0 10
lft 77 59 84 66 / 0 0 0 10
bpt 77 61 84 71 / 0 0 10 10
GM...small craft exercise caution through late tonight for gmz455-475.
Small craft exercise caution through this evening for gmz472.