Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 200243
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
943 PM CDT Mon Jun 19 2017

.UPDATE...
Waning isolated showers noted across portions of central LA and
deep east TX late this evening, due to loss of daytime
heating. Will opt to maintain mentionable POPs across the
aforementioned areas until midnight where thereafter, confidence
of nil precipitation is high. Shifted the coverage of cloud cover
as clearing skies has taken place from west to east thus,
resulting in clear skies across southeast OK, east TX, and
portions and southwest AR, and SCT-BKN mid-high clouds noted
elsewhere. Overnight temps dipping into the middle 60s across the
far northern zones seem reasonable /lower to middle 70s elsewhere/
given clearing skies, subsequently tweaking the dewpoint
temperatures and relative humidity values. Otherwise, forecast is
largely on track with another seasonably warm day on tap Tuesday
with perhaps isolated showers and thunderstorms across portions
of central LA. Thereafter, still keeping a close eye on Potential
Tropical Cyclone Three in the Gulf, as it could move onshore
across southwestern LA/southeastern TX to across the ARKLATEX late
this week. If this track holds true /and things can certainly
change/ portions of the ARKLATEX could experience breezy and wet
conditions with potential for flooding.

&&

.PREV DISCUSSION... /issued 651 PM CDT Mon Jun 19 2017/

AVIATION...
For the 20/00z TAFs, isolated to widely scattered convection
persists south of Interstate 20 across portions of East Texas and
much of Louisiana. The showers and thunderstorms should gradually
diminish and exit the area during the first few hours of the TAF
period as daytime heating wanes. Cloud cover should also scatter
from north to south as some drier air aloft moves into the region.
VFR conditions should prevail at most terminals, but a brief
window of MVFR ceilings/visibilities will be possible across Deep
East Texas, including KLFK, around sunrise Tuesday morning. VFR
conditions will prevail areawide by 20/15z. Northeasterly winds
will persist and cloud cover will increase south of Interstate 20
as a tropical low pressure system moves northward towards the
Gulf coast.

CN

PREV DISCUSSION... /issued 330 PM CDT Mon Jun 19 2017/

DISCUSSION...
Trying to get some redevelopment along the slowly southward moving
cold front which has become rather diffuse this afternoon but is
likely somewhere just south of the I-20 Corridor late this
afternoon. CAPE values per SPC`s Meso Analysis page are pushing
3k J/KG but upper forcing is weak despite the frontal forcing.
For the remainder of the evening, went with slight chance pops
along and south of the corridor with this activity likely
dissipating after midnight. Some slightly drier air is funneling
into the region in the wake of the front from the north and east
but how cool we get will depend greatly on the cloud cover
breaking up overnight.

Beyond the Tuesday portion of the forecast, have made wholesale
changes to the mid and late week periods with these changes have
to do with the developing tropical system near or just to the
north of the Yucatan. Yesterday at this time, we had a large range
of solutions as to where any developing tropical system would move
once it got in the Gulf. Those possible solutions ranged from
Brownsville, Tx. to Tallahassee, Fl. with everything in between a
possibility. This morning, the consensus has shrunk somewhat from
between Corpus, Tx. to new Biloxi, Ms. with the favored tracks of
the UKMET and ECMWF per NHC/WPC more towards a landfall somewhere
near Sabine Pass during the day Thu with the remnants moving NNE
towards N Central La/South Central Ar by Friday. Needless to say,
a track of this nature is far from certain this far out in the
forecast but will not ignore this possibility with this forecast
package. Intensity is not a huge concern before the system makes
landfall as there is still quite a bit of shear the storm will
encounter as it moves northward towards the La. Gulf Coast but a
weak tropical storm is almost certain over the next 24 hours or
so. Thus, impacts across our region will be the obvious heavy
rainfall threat with that being along and east/northeast of where
the center tracks. At this time, this would mean the eastern half
of our region and have thus increased pops accordingly, especially
during the Wed/Fri timeframe. We are too soon for the necessity
of Flash Flood Watches for our areas of the Lower Miss Valley but
Coastal Flash Flood Watches are already out from the SE La. Coast
to the Fl. Pnhdl. Needless to say, everything in this forecast
will depend on the storms inland track, thus this is a low
confidence forecast for now but this forecast will continue to be
adjusted over the next 24 to 36 hours with Flash Flood Watches
becoming possible for at least the eastern half of our region
during these time periods.

Fortunately, something a majority of the medium range progs agree
on is a rather quick movement to the north and northeast after
landfall and this is due to the systems proximity to two large
upper level ridge axis, one centered off the southeast U.S. and
the other near the Four Corners region of the country. The
interaction of an upper trough across the Central Plains will also
help to steer the remnants north and east. A very tropical airmass
will be left behind the system for the upcoming weekend as well
which will result in scattered showers and thunderstorms
continuing across our region before we finally see the effects of
yet another cold front pushing into our region from the north and
west late Sunday into Monday of next week.

Thanks for the Coordination today NHC, WPC, HGX, JAN, LCH.
Prelims to follow...13.

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  71  91  69  88 /  20  10  10  20
MLU  71  89  70  85 /  20  10  20  30
DEQ  66  91  65  91 /  10  10  10  10
TXK  68  90  69  90 /  10  10  10  10
ELD  67  90  66  87 /  10  10  10  20
TYR  71  91  69  91 /  10  10  10  10
GGG  71  92  68  90 /  20  10  10  20
LFK  75  92  71  89 /  20  10  10  40

&&

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

$$

29/09/13



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