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FXUS64 KSHV 181111
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
511 AM CST Fri Jan 18 2019

.SHORT TERM.../Today through Saturday Night/

Big changes coming to the region over the next 48 hours. First
thing first, light and variable winds this morning near a slow
moving cool front, along with low level moisture beneath a
diurnal inversion has allowed for low clouds and fog across the
region. Closer to the front, fog has become more dense. As a
result, decided to issue a Dense Fog Advisory for portions of
Deep East Texas, Northeast Louisiana, and Central Louisiana until
10 am this morning. The fog is expected to lift by mid morning, as
southerly winds pick up across the region to near 10 mph.
Unseasonably warm temperatures expected today as highs will climb
into the upper 60s across the region.

As we move into the afternoon hours today, a lee-side trough will
begin to develop and deepen across southeastern Colorado and move
toward the panhandle region of Texas/Oklahoma. At the same time,
models suggest some weak isentropic lift will develop this
afternoon and showers will spread over the region. The pressure
gradient will also strengthen at this time and winds will begin
to become more gusty from the south/southwest. A Lake Wind
Advisory may be needed during this period, but at this time, will
leave this to be decided during the later forecast package due to
timing issues. The trough will continue to push towards the
region, dragging a strong arctic front and upper low with it.
Additional showers and thunderstorms will begin to develop near
the frontal boundary. With steepening mid-level lapse rates and
cool air aloft, a hail and wind threat will be possible across
most of the region during the late evening and overnight period.
Can't rule out the possibility for an isolated tornado as well as
effective bulk shear of 40-50 kts could support some mid-level
rotation.

The front should sweep through the region by noon time on
Saturday and arctic air will spill into the region along with
gusty northwest winds near 20 mph with gusts near 30 mph. There
is the slight chance of a rain/snow mix north of a line from
Broken Bow Oklahoma to Dierks Arkansas on Saturday morning from
wrap around moisture from the associated upper low as it moves
across Central Oklahoma and Central Arkansas. All activity will
move out of the region by Saturday afternoon and much cooler
temperatures will settle across the region. Temperatures will fall
into the mid to upper 20s areawide by Sunday morning.

/20/


.LONG TERM.../Sunday through Friday/

Cold post frontal temperatures in the wake of the upper trough axis
which will be well east of the region by Sunday. The good news is
the winds should not be as strong on Sunday and with full sun, we
should see temperatures warming up into the middle 40s to lower 50s
for daytime highs on Sunday.

Weak upper level ridging sets up across our region for Monday but
looking out west, another upper level trough begins to dig across
the Four Corners Region of the Country. This will set up sfc
cyclogenesis in the lee of the Rockies for Monday with a
strengthening pressure gradient setting up across the Southern
Plains. The end result will be much warmer temperatures on Monday
with 60s returning for much of the region. The upper trough begins
to enter the Plains on Tuesday along with an associated cold front.
Look for showers and isolated thunderstorms to accompany this
feature Tuesday before exiting the region Tuesday Night. Latest 00z
medium range progs hinting at a slower trough passage Tuesday
Night/Wed time period so will need to watch this but chose to leave
Wednesday dry for now. This trough will usher in another shot of
cold air to conclude the upcoming work week.

13


&&

.PREV DISCUSSION... /issued 1153 PM CST Thu Jan 17 2019/

AVIATION...

For the 18/06Z TAF period, a range of flight conditions starting
out this period with a general trend of deteriorating cigs/vsbys
overnight as a weak frontal boundary will stall across the area.
MVFR/IFR conditions will be common across all sites through the
morning hours on Friday with some intermittent LIFR conditions
possible around daybreak. Low cigs and fog will linger through mid
to late morning before slow improvement is expected as S/SE winds
increase due the front lifting back north from the I-20 corridor.
Wind speeds will range from 10-15 kts with higher gusts on Friday.
Otherwise, MVFR/low VFR cigs are likely through Friday afternoon
as Gulf moisture continues to increase ahead of a much stronger
cold front due to arrive early Saturday. Convection should begin
to develop by around 19/00Z as pre-frontal showers and isolated
thunderstorms increase with the front not expected to move in
until just after this period concludes.

/19/


&&

.PRELIMINARY POINT TEMPS/POPS...
SHV 67 47 51 28 / 20 70 20 0
MLU 67 56 57 29 / 20 80 30 0
DEQ 62 38 40 23 / 20 60 20 0
TXK 62 41 44 25 / 20 60 20 0
ELD 66 50 53 27 / 20 80 30 0
TYR 67 40 42 27 / 20 60 20 0
GGG 67 43 46 26 / 20 60 20 0
LFK 69 47 50 27 / 20 60 20 0

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...Dense Fog Advisory until 10 AM CST this morning for LAZ005-006-
010>014-017>022.

OK...None.
TX...Dense Fog Advisory until 10 AM CST this morning for TXZ153-166-
167.

&&

$$

20/13
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