Flash Flood Warning 39, NWS Shreveport, LA

Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
1259 PM CDT Mon Jul 6 2020

AVIATION...

A weak disturbance pushing into east Texas will continue to bring
scattered showers and thunderstorms with MVFR conditions and
brief IFR conditions across the terminals into the evening. The
chance of showers and thunderstorms will continue overnight across
the terminals. MVFR ceilings will develop across the terminals by
the pre-dawn hours. Winds will be light and variable through much
of the TAF period with brief wind gusts to 20-25kts possible in
thunderstorms. /04-Woodrum/

PREV DISCUSSION... /issued 1204 PM CDT Mon Jul 6 2020/

UPDATE...

The latest RAP mid-level analysis show a 500mb weak short wave along
the TX/OK border with this energy slowly rotating south-
southeastward into East Texas. At the surface, a weak 1010mb low is
observed north of the DFW metro with an poorly-defined weak surface
trough extending eastward from this feature into East Texas and
northern Louisiana. With weak cyclonic flow observed in the 500mb-
sfc layer near the wave, this area of weak low pressure is aiding in
development of showers and thunderstorms in a very moist environment
with PWAT values in the 2-2.25" range. Instability is limited to
1000-1500 J/kg over much of the area with ongoings showers and
thunderstorms limiting energy. The exception is north of Texarkana
where SBCAPE values are in the 2500-3000 J/kg range. More widespread
showers with embedded isolated thunderstorms are rotating around the
wave into East Texas with numerous showers and scattered
thunderstorms developing along a corridor from Idabel/Broken Bow
southeastward to Texarkana into extreme northwest Louisiana.

The mid-level short wave and surface low will only slowly edge
eastward from their current position today, with showers and
thunderstorms slowly rotating around the feature and increasing in
coverage across the area. With ongoing convection across the area,
that will limit instability to around 2500 J/kg by this afternoon
with weak shear in place. Thus, do not anticipate a severe threat
today. The bigger concern is the potential for localized flash
flooding given storms potentially training over areas becoming
saturated from rain on previous days and today's rain. The Weather
Prediction Center (WPC) has Deep East Texas highlighted in a
Marginal Risk in its Excessive Rainfall Outlook. A cloudy day is
expected across much of the area today with the exception being
the eastern periphery of the wave along an area from El Dorado to
Monroe where more partly cloudy skies are expected.

While showers and thunderstorms will begin to decrease in intensity
this evening with the loss of heating, the wave to the west of the
area will continue to slowly edge eastward and providing forcing for
scattered showers and thunderstorms overnight. With this in mind,
kept 40-50% POPs overnight.

For temperatures, highs were adjusted up a few degrees for El
Dorado/Monroe with more sunshine on the eastern edge of cloud
coverage. Otherwise, temps were lowered slightly for portions of
Deep East Texas and East Texas where ongoing showers and cloud
coverage should help limit highs today. Highs will range from the
mid 80s in East Texas and Deep East Texas to the lower 90s in the
ArkLaMiss. For lows, forecast is closest to the National Blend of
Models (NBM) with lows in the lower to mid 70s across the area.
/04-Woodrum/

PREV DISCUSSION... /issued 342 AM CDT Mon Jul 6 2020/

SHORT TERM.../Today through Tuesday/

Did maintain likely/categorical pops going through the morning
Tuesday across much of E TX/N LA/extreme Srn AR, with the
convection slowly shifting ENE during the afternoon as the primary
elevated circulation along the shear axis begins to gradually
shift E into SW AR/N LA. Did trend max temps Tuesday near the NBM
guidance, but should the convection remain widespread even during
the afternoon, these may need to be scaled back a few more degrees
in later forecasts.

15

LONG TERM.../Tuesday Night through Monday/

The persistent weakness in the mid levels of the atmosphere,
responsible for the continued high rain chances for the last several
days, will be in place for one more day on Wednesday with scattered
to numerous showers and thunderstorms. This weakness is forecast to
lift out into the Appalachians by Thursday, being helped eastward by
and ridge of high pressure aloft that will also expand eastward from
the Four Corners Region of the country into the Plains. With the
arrival of this ridge axis will be much lower atmospheric moisture in
the form of lower PWATS, less in the way of upper forcing and
warming lower levels which will be best characterized by hotter
afternoon temperatures as we move into the end of the week. Did keep
slight chance pops across our extreme northern and eastern zones for
Friday given a weak disturbance rounding the ridge axis but given
the lower pwats across our region, would not think there would be
much in the way of storm coverage.

While the center of the upper level 600 dam ridge will remain
centered over the Four Corners region through the upcoming weekend,
the ridge axis will likely extend far enough into our region from
the west to limit anything but very isolated thunderstorm chances
that are too limited to mention this far out in the forecast. As we
move into the following work week, there are indications that this
ridge axis may begin to migrate more eastward into the Plains which
would further put a damper on any precipitation chances and further
enhance the heat.

Speaking of the heat, as our region becomes more under the influence
of this ridge axis to our west, look for temperatures to respond
accordingly. Highs will climb back into the lower and middle 90s
areawide for Thu, middle 90s areawide for Fri with mid to upper 90s
for the upcoming weekend, maybe pushing 100 degrees across our
western zones for Sun into Mon. Given how wet our soils are, we may
be hard pressed to see the mixing down of afternoon dewpoints. The
end result will likely be a return to Heat Advisory criteria as
early as the end of the work week but especially for the upcoming
weekend.

13

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  74  85  74  89 /  40  80  40  60
MLU  74  86  73  87 /  40  80  40  70
DEQ  72  87  71  88 /  30  50  20  60
TXK  72  86  73  87 /  30  60  30  60
ELD  72  85  72  88 /  40  60  30  70
TYR  73  86  74  92 /  50  70  40  40
GGG  73  85  73  92 /  50  70  40  50
LFK  75  87  75  93 /  50  60  40  40

&&

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

04/13/15

Hazardous Weather Outlook
National Weather Service Shreveport LA
106 PM CDT Mon Jul 6 2020

ARZ050-051-059>061-070>073-LAZ001>006-010>014-017>022-OKZ077-
TXZ096-097-108>112-124>126-136>138-149>153-165>167-071100-
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-
106 PM CDT Mon Jul 6 2020

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...This Afternoon and Tonight...

Scattered to numerous thunderstorms will be possible once again
today across the Four State Region. While an isolated severe
thunderstorm cannot be ruled out, these storms will produce strong
wind gusts, frequent cloud to ground lightning and brief heavy
downpours. Isolated flash flooding will be possible These
thunderstorm chances will likely carry over into the evening and
overnight hours as well.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday...

Scattered to numerous thunderstorms will continue across the Four
State Region through at least Wednesday. Again, some of these
storms could be strong but widespread severe thunderstorms are not
expected at this time. A drying trend should commence Thursday
through the upcoming weekend but it will become very hot during
this time as well. A Heat Advisory will likely be needed by the
end of the week into the weekend for afternoon heat indices
meeting or exceeding 105 degrees areawide.

.SPOTTER INFORMATION STATEMENT...

Activation of emergency management personnel...amateur radio
operators...and storm spotters should not be needed through
tonight. Please relay any information about observed severe
weather to the NWS while following all local, state, and CDC
guidelines.

09

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
852 AM CDT MON JUL 6 2020

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

0730 AM     FLASH FLOOD      5 N HALLSVILLE          32.57N 94.58W
07/05/2020                   HARRISON           TX   COCORAHS

            A COCORAHS OBSERVER AND RETIRED NWS EMPLOYEE
            REPORTED THAT PAGE CREEK WAS OUT OF ITS
            BANKS AND FLOODED PORTIONS OF WALKERS MILL
            ROAD NORTH OF HALLSVILLE. HIGH WATER FLOODED
            SEVERAL NEARBY FIELDS AND YARDS, AND
            SANDBAGS WERE NEEDED TO KEEP THE WATER OUT
            OF A HOME. 6.43 INCHES OF RAIN WAS RECORDED
            BETWEEN 400-730 AM ON THE 5TH.

&&

15

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
134 PM CDT MON JUL 6 2020

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

1202 PM     FLASH FLOOD      2 W TEXARKANA           33.45N 94.04W
07/06/2020                   MILLER             AR   LAW ENFORCEMENT

            FLASH FLOODING REPORTED ON SEVERAL ROADS IN
            TEXARKANA WITH VEHICLES FLOODED.

&&

WOODRUM