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fxus64 klch 261730 
afdlch

Area forecast discussion
National Weather Service Lake Charles la
1230 PM CDT sun Mar 26 2017

Discussion...
18z tafs

&&

Aviation...
the dense fog was slow to dissipate this morning, but it finally
has giving way to a mid level cu deck streaming out of the Gulf of
Mexico. VFR conditions will prevail through the remainder of the
day. Went ahead and removed fog in the tafs for tonight as the
latest guidance is indicating very little in the way of
significant fog formation. That said, the boundary layer remains
highly saturated so some patchy fog development will be possible
where winds are weak. Any fog that does develop should dissipate
by 15z. Broken to overcast cigs will dominate on Monday as another upper
level system will produce isolated showers and thunderstorms.

&&

Previous discussion... /issued 1018 am CDT sun Mar 26 2017/

Discussion...
GOES-16 visible satellite imagery and sfc observations show the
dense fog lifting to a bkn/ovc layer which should eventually
scatter out the next couple of hours. Otherwise, no changes in the
remainder of the forecast, with highs in the lower to mid 80s
expected.

Dml

Previous discussion... /issued 708 am CDT sun Mar 26 2017/

Update...
vsbys in several locations acrs southwest la have recently lowered
to around one quarter of a mile or less so have gone ahead and
extended the dense fog advisory to include all but central la and
the lakes region of southeast Texas. Visibilities should improve
by mid-morning.

24

Previous discussion... /issued 702 am CDT sun Mar 26 2017/

Discussion...
for the 3/26/17 1200 UTC taf package.

Aviation...
low clouds and/or fog across the area early this morning courtesy
of ample low level moisture and light south surface winds. Expect
IFR/LIFR to continue for another few hours, with ceilings/visibilities
improving into MVFR by late morning and possibly scattering by
early afternoon with increased boundary layer depth/mixing. Low
ceilings/visibilities are forecast to return this evening.

13

Previous discussion... /issued 505 am CDT sun Mar 26 2017/

Synopsis...
a nearly stationary cold front extends along the northern edge of
the County Warning Area from north of kaex southwest to south of kjas, as
evidenced by both metar obs and infrared stlt imagery. South of the
boundary, temperatures are in the middle and upper 60s while to
the north temps are running about 10 degrees cooler. Stlt imagery
also shows sctd to bkn low clouds south of the front along with
some patchy fog. A few pockets of dense fog have developed as well
in spots where skies have cleared.

Aloft, the latest WV imagery and upper air analysis shows the upper low
responsible to yesterday's convection now over the mid-MS valley
with its trough axis pushing east toward the southeast Atlantic
coast. Meanwhile, the next shortwave trough to affect the area is
noted upstream crossing The Four Corners region.

24

Discussion...
so far this morning, dense fog has remained fairly isltd and patchy
thanks to the band of low clouds. However, clouds have been a
little more sparse acrs lower southeast Texas and this is where dense
fog has been a little more widespread. All obs sites in this area
are showing vsbys down to 1/4sm and this is verified by area
traffic cameras. Because of this, went ahead and issued a dense
fog advisory for Jefferson and Orange counties. Meanwhile, cloud
cover has been a little more persistent acrs southwest la although
a few pockets of lower vsbys are noted. Given the spotty nature of
the dense fog in la, opted to leave out of the advisory for the
time being but will continue to monitor and expand the advisory
should it become necessary.

Fog and clouds should mix out through the morning with skies
expected to become partly cloudy this aftn. Temperatures will warm
into the middle 80s acrs much of the area today as the frontal
boundary lifts north and dissipates.

The next trough upstream will enter the Southern Plains today and
eject toward the mid-MS valley tonight into Monday. This system
will bring an increasing chc for showers and tstms late tonight
into Monday, with the best chcs acrs our northern zones. Svr
weather is not expected with this system as the better dynamics
will be north of the area. Rain chcs will decrease from west to
east late Monday as the trough quickly transits east within the
progressive pattern aloft. Some low rain chcs are expected to
linger mainly acrs northern portions of the area on Tuesday in the
vicinity of a weak sfc boundary.

The next in this rather busy series of disturbances will dig over
the western Continental U.S. Tuesday and move into the Southern Plains
Wednesday. This system will be a little deeper and stronger than
the Monday system. Showers and tstms will spread east acrs Texas on
Wednesday with likely pops expected Wednesday night into Thursday.
A strong low level jet will translate into the region helping to draw
deeper moisture over the region with precip water values climbing
to near 1.7 inches. Wind profiles show sufficient shear in the
lower to middle levels as well as decent instability, and these
factors appear to support the potential for a few strong to svr
storms late Wednesday. Storm Prediction Center also continues to indicate at least a
slight risk for the northwestern half of the area on the day 4
(wednesday) outlook. Model guidance still displays some minor
differences in the placement and strength of various features so
will continue to monitor as details get more refined.

Showers and tstms will continue on Thursday as a sfc front moves
through the area. Drier air will filter into the area behind the
front Thursday night with rain chcs ending as the main upper
system move away from the region. Temperatures aren't expected to
cool down much in the wake of this front, but slightly drier air
will make overnight temperatures Thursday and Friday night a
little more comfortable. The front will stall over the area Friday
and Saturday but dry weather is expected to prevail with aftn
highs around 80.

The front will lift back to the north by Sunday as sfc low pres
develops west of the area in concert with another trough digging
over the southwest. Model solutions diverge concerning the
evolution of this system with the GFS and Canadian favoring a
deeper and slower solution while the European model (ecmwf) remains less amplified
and more progressive late next weekend/early next week.
Regardless, rain chcs are expected to increase again just beyond
this fcst period.

24

Marine...
light to moderate southerly winds will prevail through mid-week with
seas from 2 feet over the nearshore waters to 5 feet beyond 20 nm.
Winds will strengthen and seas will build Wednesday into Thursday
as low pres deepens west of the region and moves into the area.
Shower and tstm chcs will increase as the low and associated cold
front move into the region. The front will move through the area
Thursday night with rain chcs ending and westerly winds developing
in its wake.

24

&&

Preliminary point temps/pops...
aex 84 64 83 65 / 0 20 40 10
lch 82 66 81 67 / 0 10 20 10
lft 84 67 83 68 / 10 10 20 10
bpt 82 67 83 68 / 0 10 20 10

&&

Lch watches/warnings/advisories...
la...none.
Texas...none.
GM...none.
&&

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