Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 231040
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
540 AM CDT Wed May 23 2018

.AVIATION...

Another morning of VFR conditions across all terminals this
morning. Will need to watch for an hour or two of 3-5SM VSBY
concerns at the beginning of the TAF period but otherwise, nice
flying weather is expected for the most part this morning. By mid
to late morning, should see cu field beginning to pop and once
convective temperatures are reached, another day of scattered
showers and thunderstorms affecting our airspace. Continued the
trend of mentioning VCTS at all terminal locations given the
coverage expected and will handle any terminal TSRA with
amendments if necessary. Winds will be light and variable today
except strong and gusty near thunderstorms along with brief VSBY
restrictions with convection.

Coverage and intensity should begin to wane beyond 24/00z this
evening with debris AC and Cirrus once again during the overnight
hours under near calm winds.

13

&&

.PREV DISCUSSION... /issued 342 AM CDT Wed May 23 2018/

Short Term.../Today through Thursday/

A mixture of mid and high clouds this morning on IR Imagery,
which combined with plentiful low level moisture and a little
daytime heating and you have the ingredients for scattered
convection once again across our region today. The trigger for
this activity aloft continues to be an inverted trough axis which
is centered across the SE TX Coast northward into the heart of our
region and into E OK/W AR. This feature has moved very little
over the last 24 hours and will remain in place through Thursday
as well. SPC Mesoanalysis page shows PWATS pooling upwards of 1.9
inches across our northern zones early this morning but minimum
values are as low as 1.7 inches across our southwest zones. A
myriad of outflow boundaries remain across our region as well from
convection yesterday and this will serve as the sfc trigger
necessary along with daytime heating for convection to grow and
expand through the daytime hours. High end chance pops worked well
yesterday so will stay with persistence today with our highest
pops warranted across our northern and eastern half before
tapering pops back to slight chance variety by late this evening.
MOS daytime highs today are closer to reality compared to 24 hours
ago so did not stray too much.

With the trough remaining in place overnight, mid and high clouds
again should be plentiful with the convection dissipating near or
shortly after midnight. Did undercut overnight low temps just a
degree or so given areas that see precipitation will likely fall
just below MOS forecast mins overnight.

For Thursday, expect a repeat performance with the inverted trough
remaining in place for yet another day. Again kept highest pops
across our northern and eastern half as slightly less PWATS are
noted across our eastern third on Thursday but given the trough in
place, scattered pops are still warranted.

13

Long Term.../Thursday Night through Tuesday Night/

A weak upper trough over the Northern Gulf of Mexico will help to
keep unsettled conditions in place. Heading into the weekend, this
trough will likely merge with another trough heading northward from
the Caribbean Sea. Medium range models differ considerably with the
evolution and track of this combined system. The GFS tracks the mid
level trough due northward but moves the surface low into the
Florida Peninsula. This is likely a depiction of a more subtropical
development versus tropical. On the other hand, the Canadian and
Euro models maintain a more vertically stacked system, which
suggests a tropical development. The system will likely move onshore
between New Orleans and some portion of the Florida Panhandle by
early Monday morning. The upper trough will likely remain somewhat
cut off from the main branch of the westerlies through late Tuesday.
Thus, with a relatively weak and unorganized flow aloft, it`s
movement after landfall Monday is highly uncertain.

This forecast was trended largely towards a blend of the Canadian
and the Euro, which has show better run-to-run consistency. As the
trough approaches, an increase in diurnally driven convection is
expected, especially across Southern Arkansas and Northern
Louisiana, beginning Friday and continuing into early next week. The
chances are also higher for showers and thunderstorms to persist
through the nighttime hours, but the greatest convective coverage
will continue to be during peak daytime heating.

Otherwise, temperatures will continue to slowly creep ever upward.
Daytime highs should be well into the 90s across portions of East
Texas by Monday where rain chances will generally be lower. Farther
east, temperatures may be held close to 90 degrees F, or possibly
into the upper 80s, by the enhanced thunderstorm coverage.

CN

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  90  70  92  71 /  50  30  40  20
MLU  91  70  91  71 /  50  30  50  20
DEQ  86  67  89  67 /  50  30  50  20
TXK  87  68  89  69 /  50  30  50  20
ELD  89  68  90  69 /  50  30  50  20
TYR  89  69  90  71 /  40  20  30  20
GGG  90  68  91  71 /  50  30  30  20
LFK  91  69  91  70 /  40  30  30  20

&&

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

$$

13/CN/13



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