Flash Flood Warning 20, NWS Shreveport, LA

Area Forecast Discussion
National Weather Service Shreveport LA
930 PM CST Thu Feb 22 2018

.UPDATE...
03z Sfc Analysis showing our returning warm front situated from
near Houston and Lufkin, Texas to near Natchitoches, Louisiana and
Vicksburg, Miss. This boundary has moved very little since 4 pm
but should at least move further north along its eastward flank,
moving north of Monroe and near or just south of El Dorado by 6 am
Friday Morning.

So far this evening, most of the activity as been going on across
Deep East Texas spreading north northeastward into NW LA and SW AR
and this is along a deformation zone which has set up across this
same general area. 00z NAM output along with the current run of
the HRRR has nailed this activity thus far and really begins to
focus renewed activity north and west of the returning warm front
or across our northwest zones for the remainder of the night. This
activity should orient itself along an elevated 850mb theta-e axis
which should be near or along a line from near TYR to TXK and LZK
later tonight. Already seeing an uptick in convective coverage
across these regions and therefore the ongoing forecast has a good
handle on this likelihood through the remainder of the overnight
hours. Did add areas of fog however through the overnight grids as
if you are void of the mixing effects of the convection, you will
likely see some fog overnight.

Overnight min temp forecast is very difficult as we could see
rising temperatures across our eastern zones and near steady to
slightly falling temperatures out west in and out of rain
activity. Therefore made only very slight adjustments to
temperatures overnight.

Prelims to follow...13.

&&

.PREV DISCUSSION... /issued 555 PM CST Thu Feb 22 2018/

AVIATION...
For the ArkLaTex, a warm front stretches from KLFK to KRSN/KMLU
and continues lifting Northward. VLIFR-IFR for most sites attm
except KMLU now well behind the boundary. Cigs/vsby issues will
linger well into daylight on Friday with models showing more TSTM
activity along the warm frontal boundary currently affecting KGGG
and soon for KTXK/KTYR. Warm front will lift past terminals with
MVFR/VFR expected late period and L/V winds. Outlook is for more
TSTMS for Sat and the next weak cold front drying us for 2/3 days.

/24/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  53  71  63  76 / 100  70  40  90
MLU  58  78  65  81 /  40  60  40  50
DEQ  47  60  55  71 / 100 100  80  90
TXK  47  63  59  73 / 100 100  50  90
ELD  48  67  60  76 / 100 100  40  90
TYR  45  68  62  73 / 100  90  50  90
GGG  51  69  62  74 / 100  80  40  90
LFK  53  75  66  77 /  70  50  30  90

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Flash Flood Watch through Friday evening for ARZ050-051-059>061-
     070>073.

LA...Flash Flood Watch through Friday evening for LAZ001>006-010>014-
     017>022.

OK...Flash Flood Watch through Friday evening for OKZ077.

TX...Flash Flood Watch through Friday evening for TXZ096-097-108>112-
     124>126-136>138-149>153-165>167.

&&

24/13

Hazardous Weather Outlook
National Weather Service Shreveport LA
336 PM CST Thu Feb 22 2018

ARZ050-051-059>061-070>073-LAZ001>006-010>014-017>022-OKZ077-
TXZ096-097-108>112-124>126-136>138-149>153-165>167-232145-
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-
336 PM CST Thu Feb 22 2018

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...

Moderate to possibly heavy rainfall will return to portions of
the Four-State Region this afternoon and again tonight. Additional
rainfall amounts of one to three inches will exacerbate any
ongoing flooding and may bring flooding to new areas, especially
in the I 30 corridor and surrounding areas. A Flash Flood Watch
remains in effect through midnight Friday night.

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

Moderate to heavy rainfall will persist on Friday across portions
of the Four-State Region leading to a continual threat for flash
flooding. Precipitation should shift north of the region by Friday
night. An approaching upper level disturbance and associated cold
front will bring additional rainfall for portions of the region
on Saturday, and the threat for flash flooding will continue.
Aside from the flooding potential, some of these thunderstorms
could become strong to severe with damaging winds and isolated
tornadoes the primary threats. The severe and heavy rainfall
threat will diminish from west to east Saturday night with the
frontal passage.

.SPOTTER INFORMATION STATEMENT...

Activation of emergency management personnel...amateur radio
operators...and storm spotters may be needed for ongoing and
additional flooding.

12