Area Forecast Discussion
Issued by NWS Shreveport, LA

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004
FXUS64 KSHV 231040
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
540 AM CDT THU JUN 23 2016

.AVIATION...
High pressure centered over TX bringing mostly vfr skc conditions
areawide with only a few wispy cirrus clouds. High based cumulus
to develop again btwn 23/15-18z. However with increasing capping
inversion and dry air in mid lvls expect little to no convection.
South winds mainly 5 to 10 kts in daytime with lgt south winds
overnight keeping any patchy fog to a minimum this am and again
overnight./VII/.

&&

.PREV DISCUSSION... /issued 442 AM CDT THU JUN 23 2016/

DISCUSSION...
The moring water vapor imagery indicates upper ridging anchored over
the Srn Plains ewd across the lower MS Valley and across the Gulf
Coast states. S of this ridge...a weak inverted H700-500 trough
depicted on the 00Z raob analysis still lingers over SE TX into Cntrl
LA...and may provide focus for isolated convection this afternoon once
peak heating/instability is realized...as was the case Wednesday. Have
continued mention of slight chance pops this afternoon for Deep E TX
and the Srn sections of Ncntrl LA...although subsidence from the ridge
aloft should help to taper the convection later this afternoon such
that pops should not be needed this evening. One interesting feature
from the 00Z raob analysis was the fact that the KLCH raob sampled
noticeably drier air and lower PW/s...which the NAM has best
initialized on and advects this drier air N into E TX/N LA this
morning before modifying this afternoon. This should aid in a little
better mixing than what was observed Wednesday...even as temps reach
the mid 90s. Thus...heat indices should be near if not slightly lower
than what was observed Wednesday...with mixing possibly a little more
difficult to obtain over SE OK/portions of SW AR as the higher PW air
will reside over these area. As a result...some localized areas in
McCurtain County OK and SW AR may see heat indices around/briefly
higher than 105 degrees where better moisture pooling occurs. After
coordinating with the LZK and JAN WFO/s...have opted to forego the
Heat Advisory given the localized nature of the criteria being met.

The weak H700-500 inverted trough is progged to light WNW tonight and
weaken...with the upper ridge center expected to gradually slide SE
into the Lower MS Valley. Farther S...an upper level low pressure area
depicted on the morning water vapor imagery over the Wrn Gulf will
slowly move ashore the Ern MX coast into Deep S TX later today...before
drifting NW along/just s of the Rio Grande to the Big Bend region by
Saturday. The position of this weakening low may help to enhance the
seabreeze especially along the TX coast...with isolated convection
possibly affecting portions of Deep E TX by afternoon. Have maintained
slight chance pops for these areas...with the seabreeze again possibly
affecting these areas Saturday as the ridge center shifts farther SE
into NE LA/MS. Temps should continue to warm slightly Friday and
Saturday especially over Scntrl AR/NE LA...but mixing may be enough
such that heat indices should be just below criteria over these areas.

The progs suggest that the ridge center should begin to slowly
retrograde back NW over the region Sunday thus tapering any seabreeze
convection...with the ridge continuing to retrograde farther NW into
the Rockies/Wrn portions of the Srn Plains Monday as longwave
troughing begins to dig SE across the Great Lakes region into the OH
Valley. This should have little effect on temps though early next
week...until a weakness/shear axis associated with the longwave trough
to our NE begins to ride S around the ern periphery of the ridge
across Ern OK/AR Monday and farther S into the region Tuesday. This
should focus more sct convecton over the region especially during peak
heating Tuesday...and possibly Wednesday as the ECMWF/GFS depict this
shear axis becoming stationary across E TX/N LA. The convection/cloud
cover should knock off at least a couple degrees off of temps by
midweek...with additional weaknesses aloft possibly affecting the
region with sct convection by late week and into the 4th of July
holiday weekend with the development of another longwave trough E of
the MS Valley.

Thank you WFO/s LZK and JAN for coordination this morning. Prelims to
follow below...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  95  76  94  75 /   0  10  10  10
MLU  94  74  95  74 /  10  10  10   0
DEQ  94  74  93  72 /  10  10  10  10
TXK  94  75  94  74 /   0   0  10   0
ELD  93  74  94  73 /   0   0  10   0
TYR  95  75  94  75 /   0  10  10  10
GGG  94  75  94  74 /   0  10  10  10
LFK  93  73  94  74 /  20  10  20  10

&&

.SHV Watches/Warnings/Advisories...
AR...None.
LA...None.
OK...None.
TX...None.
&&

$$



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