Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 231032
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
532 AM CDT Wed Aug 23 2017

.DISCUSSION...
Clouds are increasing overhead along and North of I-20. Recent
radar coverage over S AR has diminished a bit, but the frontal
boundary is holding on too heavier elements in Howard Co. Overall,
recent coverage is increasing over southeast OK and northeast TX.
Both rain areas appear to be associated with old MCVs along the
front and thus the sustained convection areas. Northerly surface
winds are filtering across the I-30 corridor at this time. SE
winds or calm prevails ahead of the southward sinking boundary.

HRRR is lacking luster and other models are all over the place
with QPF making a likely area difficult to pinpoint so as a result
50 pops are widespread between both 6 hr periods of pop while
still sinking southward. Water vapor is showing the upper ridge
out West and the long wave trough over the Great Lakes and
Midwest with NW flow aloft. Low levels winds are light, but light
NW flow can be found at cirrus level on our 06Z sounding. Storm
motion is quite slow and could bring some heavy downpours in this
process as heating enhances lift and likewise rainfall amounts
coming this afternoon, spotty as it is modeled to be today.

The front will wash out as it works southward over the next day
with movement very slow for areas South of I-20 as rain chances
will be lingering along the soon to be stationary boundary. By
Friday rain areas will begin to move back to the Northeast as the
tropical push over the W Gulf surges copious amounts of PWAT as
Harvey lumbers Northward. The spaghetti model plots have shifted
landfall more toward the middle Texas coastal bend over the last
day or so.

The 00Z long range models are along the same lines, but with
varied paces. Obviously this would bring a greater flooding threat
to many areas in TX and LA. The WPC has some hefty totals of 5-10
or more inches in the 5 and 7 day outlooks. Meanwhile, the
surface high over the NE U.S. increases in strength and will be
holding back moisture along the fringe and possibly affecting how
much moves Northward out of the Gulf. As depicted by WPC, we will
be seeing a huge gradient of total amounts in the ArkLaTex. Most
of this rainfall will be south of I-20 in general. The 23/06Z run
of the Euro is now looping Harvey along the LA coast into midweek
while the GFS remains much more progressive for our area anyway.
/24/






&&

.PREV DISCUSSION... /issued 1139 PM CDT Tue Aug 22 2017/

AVIATION...
Scattered showers and thunderstorms well northwest of ktxk have
been maintained by a nearby cold frontal boundary for the majority
of the evening, but has since showed signs of oozing southeast to
across northern McCurtain county. Short term and high-res computer
models hint at this activity struggling to make southward
progress, hence remaining north of ktxk, but a VCSH mention for
the said terminal is not unreasonable. The frontal boundary is
expected to continue its slow southeastward movement overnight
through tomorrow which will veer the light southerly/variable
winds to the north-northeast at 4-7 kts. Tomorrow`s daytime
heating coupled with a lingering boundary and moist low
atmospheric levels, will result in -SHRA/-TSRA, though latest
model runs do not keep the convection confined to the boundary. It
is shown to become isolated-scattered in nature, making it
difficult to pin-point terminal impingement. Confidence is high
enough to insert a TEMPO group for -TSRA at keld and ktxk where
the convection may hold together, but break apart as it progresses
southward. Elsewhere, a VCTS during the afternoon-early evening
hours seem reasonable. Otherwise, SKC-FEW VFR CIGS late tonight
will become SCT-BKN by tomorrow afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  93  72  87  71 /  50  30  20  10
MLU  90  70  87  69 /  50  30  20  10
DEQ  87  67  85  64 /  50  20  10  10
TXK  89  69  85  67 /  50  30  10  10
ELD  88  69  86  66 /  50  20  10  10
TYR  92  73  87  71 /  50  30  30  20
GGG  92  73  87  70 /  50  30  20  10
LFK  94  75  89  73 /  40  30  30  30

&&

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

$$

24/29


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