Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 202244
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
444 PM CST Sat Jan 20 2018

.AVIATION...
Currently dealing with a mixture of MVFR/VFR ceilings across our
airspace ranging from 15hdft to 6kft. Those terminals with VFR
ceilings should quickly drop to MVFR conditions and all terminals
will likely become IFR during the overnight hours as well. Cannot
rule out some patchy drizzle or light showers overnight through
the early morning hours on Sunday which would allow for reduced
VSBYS and LIFR ceilings but that should temporary and thus while
TEMPO groups were added for the possibility of the reduced VSBYS
overnight into Friday, did not bring ceilings below IFR
conditions. If there is any improvement ceiling wise on Sunday it
won`t be much but did allow ceilings to climb back into the MVFR
category but just barely. Also introduced the mention of VCSH for
our western terminal locations only Sunday Aftn. Convection ahead
of an approaching trough of low pressure will likely begin
affecting our terminal locations just beyond this TAF cycle.

S to SSE winds overnight ranging from 6-12kts will increase on
Sunday, especially across our NE TX terminal locations where gusts
could approach 25kts at times.

13

&&

.PREV DISCUSSION... /issued 357 PM CST Sat Jan 20 2018/

DISCUSSION...
A weak upper trough remains situated over Southeast Louisiana and
Southwest Mississippi. Increasing low level southerly flow has
allowed Gulf moisture to surge northward, and the weak trough has
provided just enough ascent for some widely scattered showers
today. A few lingering showers will remain possible through the
evening and overnight hours. Patchy drizzle and fog is likely
across much of the area tonight as low level moisture continues to
increase.

During the day Sunday, the surface pressure gradient will increase
ahead of a strong surface trough. Sustained wind speeds above 15
kts, with gusts near 25 kts, are expected across portions of
Northeast Texas. Later shifts will probably need to issue a Lake
Wind Advisory, but I held off with this forecast package as some
uncertainty remains regarding the exact areas that will need it.
Typically, with such strong southerly flow, warm air advection and
compressional warming ahead of a strong surface trough and cold
front will result in very warm temperatures. While daytime
temperatures should warm near or above 70 degrees F in most
locations, I lowered the high temperature forecast just a bit as
thick cloud cover and drizzle/developing showers should keep the
warming in check.

By late Sunday morning, convection is expected to develop just
west of the area across Texas and Southern Oklahoma ahead of an
advancing dryline. A strong upper trough will emerge onto the High
Plains of Eastern Colorado and Western Kansas by Sunday evening
and will eject the entire system northeast overnight Sunday and
into Monday morning. The dryline and the strongest convection
should affect our area late Sunday afternoon and into mid morning
Monday. Despite only meager instability, shear profiles are
sufficient to support at least a marginal severe weather threat.
Damaging winds and isolated tornadoes should be the primary
threats. Storm mode will likely be linear after sunset Sunday. If
temperatures are warmer than currently anticipated, this will lead
to greater instability and an increased threat for severe weather.
As the system ejects Sunday night, a Pacific cold front will
quickly overtake the dryline and the convective complex should
surge eastward Monday morning, finally exiting the area by 15z
Monday morning.

Much of the remainder of the work week should be relatively quiet
as a surface high pressure settles overhead. For Tuesday through
Thursday, daytime temperatures will likely be near 60 degrees F,
and overnight lows will be near or below freezing mainly along and
north of the U.S. Highway 82 corridor. By Friday, low level
southerly flow returns bringing Gulf moisture back to the region
just in time for the next major upper trough and cold front to
move across the Central U.S. More wet weather will be possible
heading into next weekend.

CN

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  59  71  50  60 /  20  40  80  10
MLU  54  73  56  63 /  20  30  80  30
DEQ  57  68  43  56 /  20  70  80  10
TXK  58  70  46  58 /  20  50  80  10
ELD  57  71  49  59 /  20  30  80  10
TYR  59  70  44  59 /  20  70  80   0
GGG  58  71  46  60 /  20  60  80   0
LFK  60  73  50  61 /  20  50  80   0

&&

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

$$

CN/13



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