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000
FXUS64 KSHV 230923
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
423 AM CDT Sat Sep 23 2017

.DISCUSSION...
An upper ridge continues to dominate our weather and will help
keep warm conditions in place for the next few days. The axis of
the ridge is located from Central Texas, through the ArkLaTex, and
into the Great Lakes. Farther to the west, a large trough
continues to dig over the Western CONUS. This trough will begin to
affect the area during the middle of next week.

In the short term, latest water vapor loops indicate very dry air
aloft leading to clear skies across the region this morning.
Despite low surface dewpoint depressions, fog is expected to
remain patchy this morning. In previous days, the low-level
southerly flow was a bit stronger, which led to advection fog.
The fog this morning is more radiational in nature and is having
a difficult time developing as soil moisture is not very high
across the area. The current weather pattern, which is more
typically of mid summer, will once again allow for the chance of
isolated diurnal convection today, mainly associated with any
intrusion by the sea breeze. A weak, broad upper low currently
over Southern Georgia will drift west along the Northern Gulf
Coast during the next couple of days. Convective coverage may
increase slightly as vertical ascent increases slightly due to the
approach of the upper low today through Monday. Overall rain
chances will remain fairly low as deep layer moisture is lacking.
Otherwise, daytime temperatures will continue to hold steady in
the low to mid 90s.

By Tuesday and into Wednesday, the Western CONUS trough is
expected to split into two parts. One part will eject east-
northeast in the northern stream of the westerlies, while a second
shortwave trough becomes cut off over the Desert Southwest. The
northerly trough axis should help to push a cold front through the
area next Wednesday. At the same time, an upper ridge over the
Gulf will move westward and expand over the CWA. The resulting
flow aloft will likely shunt most of the deep layer moisture west
and north of the Four State Region. The best large scale forcing
will also be far to the west closer to the cut off low. The best
chances for scattered showers, possibly a thunderstorm, should be
in the post-frontal airmass late Wednesday and Thursday as the
center of the upper ridge moves west of the area.

Compared to previous days, the models are in much better agreement
regarding the synoptic evolution and timing of the features during
the latter half of next week. Unfortunately, this agreement is
also in regards to lower rain amounts and lower rain chances. The
ECMWF has been by far the most consistent model with this system.
Despite the lower rain chances with this forecast package in the
extended periods, the models also show good agreement in the
building of a Canadian surface high into the region behind the
front. This airmass should bring much cooler weather to the area
for Thursday through next weekend.

CN

&&

.PREV DISCUSSION... /issued 1150 PM CDT Fri Sep 22 2017/

AVIATION...
VFR conditions prevailing attm but some patchy fog will begin
developing shortly at the LFK and MLU terminals. Made very few
changes to the 06z TAF package compared to the 00z package and
this will include the possibility of dense fog at the LFK and MLU
terminals the closer we get to sunrise Saturday Morning.
Elsewhere, LIFR/IFR ceilings will be possible at the TYR/GGG/LFK
terminals as well and cannot rule out at least IFR ceilings
shortly after sunrise at the SHV terminal as well. All low
ceilings will lift and/or scatter out by mid to late morning
with VFR conditions prevailing from late morning through the
afternoon on Saturday. Very isolated showers will once again be
possible across the region on Saturday but chances are too limited
to warrant a mention in this package attm.

13

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  94  71  93  71 /  20  10  20  10
MLU  93  70  92  69 /  20  10  20  10
DEQ  92  69  90  68 /  10  10  20   0
TXK  92  71  91  69 /  10  10  20   0
ELD  92  69  91  68 /  20  10  20   0
TYR  92  71  91  70 /  10  10  10  10
GGG  93  71  92  69 /  10  10  20  10
LFK  93  71  92  70 /  20  10  20  10

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&

$$

09/05