Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 162031

Area Forecast Discussion
National Weather Service Shreveport LA
331 PM CDT Wed Aug 16 2017

Late this aftn, the synoptic pattern was characterized by an UL
ridge across southeast CONUS that is aiding in drifting an inverted
UL trough axis northwest from southeast LA to near central, whilst
concurrently a more potent UL trough was noted moving east-northeast
across the Central Plains. These disturbances coupled with
plentiful low level moisture /dewpoints in the 70s/ and daytime
destabilization has led to the development of isolated to
scattered showers and thunderstorms across portions of central LA,
northwest LA, Deep East TX, east TX and southwest AR.
Southwesterly mean flow of 15-20 kts suggest this precip activity
is moving at a decent speed, thus overly significant rainfall is
not expected but brief moderate rainfall is certainly possible.
Concurrently, a slightly tightened pressure gradient across east
TX has resulted in south- southwest sfc wind speeds of 10-13 kts
sustained with higher gusts per 20Z metars, which is below Wind
Advisory criteria. Stratus deck was a bit slow to erode earlier
this morning, though SCT-BKN mid to high level cloudiness remained
in its wake. Despite the cloud cover, temps still managed to warm
to seasonal norms. Sfc winds having a bit of a downslope wind
component equates the entrainment of drier air. In fact, although
dewpoints are in the 70s, dewpoints have mixed out from the middle
70s of earlier this morning to lower 70s particularly across east
TX. This is just dry enough to mitigate Heat Indices from rising
above 105 degrees.

Shortly after sunset, short term solutions such as the HRRR and the
NAM hint at a decrease in the spatial extent of precip as the weak
UL disturbance near central LA wanes significantly. However,
attention will turn to the cold frontal passage extending from the
Plains UL trough that will move across southeast OK overnight. Given
ensuing moist atmospheric conditions, this will be a focus for the
redevelopment of convection, that could impinge on southeast OK,
extreme northeast TX and southwest AR per model solutions. The fropa
will ooze farther southeast to across extreme northeast TX and
southwest AR tomorrow aftn, and with daytime destabilization, this
will lead to ongoing convection that could near northwest LA. Gusty
winds and brief moderate rainfall could accompany this activity. The
UL trough will quickly translate to across the Great Lakes Region
tomorrow night, and loss of daytime heating will promote diminishing
precip chances. On Friday, the UA ridge across the southeast
CONUS will commence to retrograde across southern LA to across
southeast TX, whilst an UL shortwave trough moves onto the
Northern plains which will result in west-northwest flow aloft.
Embedded impulses within the flow aloft coupled with a /albeit
weakened/ lingering frontal boundary and continued moist
conditions /PWATs aoa 2.00 inches/ will generate scattered showers
and thunderstorms across the majority of the Four-State Region
/though Deep East will be less favorable given it will be closest
to the retrograding UA ridge/. Thereafter, the UA ridge is
exhibited to wobble within the proximity of the FA, though not
directly overhead. Embedded weak impulses and a moist atmosphere
will cause the development of scattered showers and thunderstorms
during the daytime hours this weekend-early next week before
waning after sunset, hence being diurnally driven given lack of an
overly strong synoptic signal.

Temps will be a degree or two warmer tomorrow through Sunday than
what they were today, due to the nearby UA ridge. Ensuing moist
conditions will cause heat indices to increase to between 105-109
degrees across portions of Deep East TX and central LA commencing
tomorrow early aftn through early evening. Will therefore elect
to issue a Heat Advisory which will be in effect from noon
tomorrow through 7 pm CDT across the aforementioned areas May
need to consider additional Heat Advisories Friday and perhaps
through the weekend across the southern zones, as it will be
hottest at those locales. Next week, temps will drop back down
to seasonal norms once the UA ridge ceases to wobble near the
region and shift farther west to across southwest TX.


SHV  78  93  76  94 /  10  20  20  40
MLU  76  92  75  92 /  20  20  20  40
DEQ  76  87  73  91 /  40  50  20  40
TXK  77  88  74  92 /  20  40  20  40
ELD  77  90  74  92 /  10  30  20  40
TYR  79  92  77  94 /  10  20  20  20
GGG  79  92  77  94 /  10  20  20  30
LFK  78  96  77  95 /  10  20  10  20


LA...Heat Advisory from noon to 7 PM CDT Thursday for LAZ010>014-

TX...Heat Advisory from noon to 7 PM CDT Thursday for TXZ149>153-



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