Flash Flood Warning 32, NWS Shreveport, LA

Area Forecast Discussion
National Weather Service Shreveport LA
738 AM CDT Thu Aug 10 2017

.AVIATION...
For the 10/12Z TAF period, IFR/LIFR conditions are affecting most
terminals this morning as a pesky frontal boundary remains stalled
across the region. Convection has steered clear of most sites this
morning except for MLU where showers and embedded thunderstorms
are still ongoing at TAF issuance. Expect this convection to keep
drifting eastward through the rest of the morning with additional
development this afternoon, which may affect our remaining sites
along I-20 and south at LFK. However, due to scattered coverage,
have opted for VCTS this afternoon at SHV/MLU/LFK and will handle
amendments as needed for any on-station development. Otherwise,
light and variable winds this morning will become S/SW later today
around 4-8 kts. Cu field this afternoon will lift and scatter for
VFR conditions to return with daytime heating, diminishing after
sunset with mainly lingering cirrus after 11/00Z.

/19/

&&

.PREV DISCUSSION... /issued 346 AM CDT Thu Aug 10 2017/

DISCUSSION...
Isolated to scattered showers and a few thunderstorms have endured
early this morning, across portions of central LA and Deep East TX.
A warm front draped from Deep East TX to across extreme southwest
AR, has aided to maintain a moist atmosphere particularly in the
lower levels /dewpoints in the 70s/. An UL low translating
eastward across southern LA coupled with a moist atmosphere has
provided the synoptic spark to generate the aforementioned precip.
Weak southwesterly mean flow /15 kts or less/ and PWATs of
2.00-2.50 inches poses a threat for localized flooding,
particularly across portions of central LA where training of
storms/very little movement has occurred. In fact, dual-pol rain
estimates over the past hour has been approaching 2.50 inches over
northeast Grant Parish, with precip continuing to fall. The HRRR
model has a pretty good handle on how the precip will evolve and
as such, has rainfall totals ranging from 3.00-6.00+ inches
through 12Z. With a Flash Flood Warning already issued, this
expected trend can not be ignored so will elect to issue a Flash
Flood Watch for portions of central LA, in effect until 15Z where
thereafter, precip is exhibited to wane significantly. However,
motorists should continue to use caution as water covered roadways
may lead to forced alternate routing. Concurrently, flow aloft is
commencing to veer a bit to the northwest across the Southern and
Central Plains, and an embedded impulse within the flow having
developed a now weakened MCS across central OK. Although this MCS
is poised to continue on its southeastward trek, the HRRR
exhibited it deteriorating aoa sunrise just northwest of the FA.

Thereafter, a desert southwest UA ridge is anticipated to push
eastward to across south central TX by tomorrow, thus sharpening
the southwest flow aloft across the region. The warm front will
have washed out but ensuing sfc srly flow will maintain a moist
environment. Several consecutive embedded impulses within the flow
northwest aloft will set the stage for a wet period, commencing
tomorrow through early next week. Although moderate rainfall and
any lingering outflow/sfc boundaries being a focus for moderate
rainfall will certainly be at play throughout the extended period,
long term solutions has honed in on Saturday night in particular,
being a heavy rainfall event /especially across the northwest
zones/. The Weather Prediction Center has a nearby 3.00 inch
bulls-eye rather close to southeast OK on Saturday night. At this
time, will mention heavy rainfall potential on Saturday in the
Hazardous Weather Outlook, but additional highlights may be
warranted as the event draws near. Late next week, long term
solutions show the UA ridge encompassing the western 2/3rds of
the FA, leading to best chances of precip affecting the eastern
zones.

CWA-wide 90 degree temps is not expected for the next 7 days, given
expected rainfall and extensive cloud cover. Should see temps in the
upper 80s to lower 90s, with the coolest weather noted across the
northern zones.

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  89  76  91  75 /  50  20  50  30
MLU  85  73  91  73 /  90  20  60  40
DEQ  90  73  88  71 /  30  20  60  40
TXK  88  74  89  73 /  30  20  60  40
ELD  87  73  89  72 /  50  20  60  40
TYR  90  75  92  75 /  20  10  30  20
GGG  90  75  91  75 /  30  20  50  20
LFK  91  76  92  75 /  40  20  30  10

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...Flash Flood Watch until 10 AM CDT this morning for LAZ005-006-
     013-014-019>022.

OK...None.
TX...None.
&&

19/29

Hazardous Weather Outlook
National Weather Service Shreveport LA
542 AM CDT Thu Aug 10 2017

ARZ050-051-059>061-070>073-LAZ001>006-010>014-017>022-OKZ077-
TXZ096-097-108>112-124>126-136>138-149>153-165>167-111045-
Sevier-Howard-Little River-Hempstead-Nevada-Miller-Lafayette-
Columbia-Union-Caddo-Bossier-Webster-Claiborne-Lincoln-De Soto-
Red River-Bienville-Jackson-Ouachita-Sabine-Natchitoches-Winn-
Grant-Caldwell-La Salle-McCurtain-Bowie-Franklin-Titus-Camp-
Morris-Cass-Wood-Upshur-Marion-Smith-Gregg-Harrison-Cherokee-Rusk-
Panola-Nacogdoches-Shelby-Angelina-San Augustine-
542 AM CDT Thu Aug 10 2017

This Hazardous Weather Outlook is for portions of south central
Arkansas, southwest Arkansas, north central Louisiana, northwest
Louisiana, southeast Oklahoma, east Texas and northeast Texas.

.DAY ONE...Today and Tonight...

An upper level low pressure system coupled with a rather moist
atmosphere resulted in the development of isolated to scattered
showers and thunderstorms, across portions of deep east Texas and
north central Louisiana this morning. Rainfall rates upwards of
around two inches per hour across north central Louisiana pose a
threat for flash flooding, especially across low lying and poor
drainage roadways. A Flash Flood Watch is in effect until 10 AM
CDT for La Salle, Grant, Winn, Caldwell, Jackson, Ouachita,
Lincoln and Union Parishes.

By early this afternoon, the threat for heavy rainfall will be on
the decline as the precipitation commence to wane. However,
daytime destabilization may lead to the resurgence of additional
isolated to scattered showers and thunderstorms across portions of
the Four-State region, before diminishing shortly after sunset.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday...

Precipitation coverage will be on the rise Friday through early
next week, as a series of embedded disturbances within northwest
flow aloft interacts with a moist atmosphere. Gusty winds,
moderate to heavy rainfall and consequently localized flooding
will be the main threats with the stronger storms.

.SPOTTER INFORMATION STATEMENT...

Activation of emergency managers, spotter networks, and amateur
radio operators, may be needed for rainfall and potential flood
reports this morning through early afternoon.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
504 AM CDT THU AUG 10 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0500 AM     FLOOD            9 SSE WINNFIELD         31.81N 92.58W
08/10/2017                   WINN               LA   LAW ENFORCEMENT

            FLOODING ACROSS U.S. HIGHWAY 167 BOTH NORTH
            AND SOUTH BOUND DIRECTIONS. THERE ARE ALSO A
            FEW SECONDARY ROADS THAT MAY BE COVERED WITH
            WATER IN THE PARISH NEAR WINNFIELD.

&&

FB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
605 AM CDT THU AUG 10 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 AM     FLOOD            WEST MONROE             32.51N 92.15W
08/10/2017                   OUACHITA           LA   PUBLIC

            CYPRESS STREET (FOUR LANE STREET) NEAR THE
            OUACHITA RIVER DOWN TO ONE LANE IS BECOMING
            ALMOST IMPASSABLE.

&&

FB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
632 AM CDT THU AUG 10 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0630 AM     FLOOD            WINNFIELD               31.93N 92.64W
08/10/2017                   WINN               LA   PUBLIC

            VEHICLES STALLED DUE TO HIGH WATER ALONG
            HIGHWAY 84 NEAR WINNFIELD. MULTIPLE STREETS
            IN WINNFIELD ALSO COVERED WITH WATER.

&&

FB