FXUS64 KSHV 271730

Area Forecast Discussion
National Weather Service Shreveport LA
1230 PM CDT Tue Oct 27 2020

IFR/LIFR conditions may improve to MVFR briefly across select
terminals through 28/00Z with conditions again deteriorating to
IFR/LIFR thereafter. VCTS conditions possible across area
terminals after 28/06Z with light rain expected after 28/12Z.
Otherwise, northeast winds 5 to 10 knots this afternoon increasing
to 10 knots overnight and diminishing to 5 to 10 knots on
Wednesday. /05/


.PREV DISCUSSION... /issued 1027 AM CDT Tue Oct 27 2020/

Lingering frontal boundary along a line from McCurtain county
Oklahoma to Toledo Bend to service as the focus for low clouds and
reduced visibilities across the region this morning. Will send
out a quick update to mention patchy fog, mainly across the
western half of the ArkLaTex. Otherwise temperatures on track to
remain nearly stable in the 50s across the I-30 corridor and
possibly approaching near 70 degrees across portions of north
Louisiana. /05/

PREV DISCUSSION... /issued 401 AM CDT Tue Oct 27 2020/

SHORT TERM.../Today through Wednesday/

A large, strong upper trough currently over Southern Arizona will
become cut off over Southwest New Mexico today. A broad area of
large scale forcing associated with this trough combined with
strong isentropic ascent along a frontal boundary at 850 hPa
continues to result in a broad area of precipitation from West
Texas east-northeast into Oklahoma, Northern Arkansas, and
Southern Missouri. The southeast edge of this precip continues to
occasionally affect Southeast Oklahoma and adjacent portions of
Southwest Arkansas and Northeast Texas. Patchy drizzle also
persists north of a line from Jacksonville TX, to Shreveport, to
El Dorado AR. The drizzle and rain should gradually retreat more
to the northwest resulting in an end to the drizzle and decreasing
PoPs through early this afternoon.

Meanwhile, Hurricane Zeta has made landfall on the Yucatan
Peninsula and will be accelerating northward into the Gulf of
Mexico. Increasing mid-level flow off the Gulf ahead of Zeta will
provide more warm and moist air to interact with a surface low and
quasi-stationary front just south of the forecast area. Showers
will begin to increase across Deep East Texas and Central
Louisiana late this afternoon and will continue to spread
northward tonight.

While Zeta approaches the Louisiana coast, the strong upper trough
will move into West Texas by Wednesday morning. Large scale
forcing ahead of the trough will increase across much of the
region. Combined with the influence of Zeta, widespread showers
and thunderstorms are pretty much a certainty for the entire
forecast area on Wednesday. No significant wind impacts from Zeta
are expected in our area. While there may be some locally heavy
rainfall on Wednesday, the fast movement of Zeta combined with the
northeast ejecting surface low and frontal boundary should keep
this time window relatively small. In fact, storm total rainfall
amounts are generally expected to remain under 2 inches, so no
widespread flooding threat is anticipated.


LONG TERM.../Wednesday Night through Monday/

Rain will be ongoing Wednesday night, as the front begins its final
push through the region. During this time is when the Four-States
region can expect to see some of the heavier rainfall rates, with
moderate to heavy rain expected at times. While localized flash
flooding can`t be ruled out, given how progressive this system is,
widespread flooding and flash flooding are not longer anticipated
with the forecast QPF values. Lingering showers will be possible in
our far eastern zones into early Thursday morning, but this activity
will quickly diminish as dry air is quickly pulled into the region
behind the front. Regarding precipitation and FROPA, long-range
guidance suggests this may be the last precipitation we see for the
next 7+ days. Behind this trough, a closed low develops off the
coast of California, keeping our predominant 500mb flow from the NW.
This would keep drier air overhead for some time.

The most notable change in the long-term forecast tonight are
adjustments to overnight lows and afternoon highs. Overnight
guidance is much slower on removing all of the clouds from the
region, and cold air-advecting winds are slightly stronger as well.
This would result in much cooler overnight lows, and afternoon highs
for the next several days. Afternoon highs for Thursday currently
range from the mid 50s north, to the mid 60s south. Overnight lows
may even dip below 40 degrees in our far northern zones Friday
morning, with mid 40s elsewhere. These well below average
temperatures will likely stay through the remaining long-term, as
500mb flow shows no signs of letting off NW flow.



SHV  56  63  46  59 /  60 100  60  10
MLU  59  71  52  63 /  70 100  70  20
DEQ  51  58  44  55 /  40  90  70  10
TXK  51  60  44  56 /  50 100  70  10
ELD  52  61  46  58 /  60  90  80  10
TYR  54  60  43  58 /  60  90  20   0
GGG  56  63  43  60 /  40  90  30  10
LFK  61  71  45  63 /  50  90  20   0





NWS SHV Office Area Forecast Discussion