Tornadoes and Flash Flooding in Arkansas, April 29 to 30, 2017

Area Forecast Discussion...Update
National Weather Service Little Rock AR
640 AM CDT Sat Apr 29 2017

.AVIATION...

Overall MVFR ceilings over northern areas with patchy where the main
convection area is this morning. Mostly VFR ceilings central and
southern areas with patchy areas of MVFR and isolated IFR
conditions. The frontal boundary will be nearly stationary over
northern AR, and be the focus for convection this morning. Along and
south of this front, mainly VFR conditions will be seen, except some
patchy MVFR lower clouds. The main convection will affect northern
Taf sites, with MVFR conditions. Winds will be northeast at 5 to 15
mph north of the frontal boundary, while southeast at 5 to 15 mph
with some gusts to around 20 mph south of the boundary. Winds south
of the frontal boundary will become elevated at 10 to 20 mph with
gusts to around 25 to 30 mph. A low level jet remains over the area,
and low level wind shear will be possible through this morning.
Later today, especially in the afternoon to evening and tonight,
additional convection will develop over most of AR as the upper
system and cold front move through AR. (59)

&&

.Prev Discussion.../ Issued 341 AM CDT Sat Apr 29 2017
.DISCUSSION...

Main concerns in this forecast remain the potential for severe
storms, and the flash and river flooding due to the heavy rain. A
flash flood watch remains in effect currently through Sunday
evening.

Current convection over northwest AR has continued to move
northeast, and only early did it affect my CWA. The warm front was
slowly lifting northward and has basically lifted to the sagging
cold front into one boundary, and at 06Z it was from just south
of KFSM, to north of KRUE to north of KARG. Most of the upper lift
in Friday evening and currently is over NE OK moving to SE MO,
per short range models. This area has seen severe storms with very
heavy rain. Atmosphere over AR remains very moist and unstable,
and when lift shifts more south today, and especially with the
frontal boundary over northern AR and as it moves through the
state, storms, some severe, will move across AR. 00Z KLZK precip
water value was 1.35 inches, with CAPE values in the 2K+ range, LI
-4+, as well as a veering shear profile. Aloft the upper low pressure
 center was over the four corner state area, and rotating energy
 to the east and northeast.

&&

.SHORT TERM...Today Through Sunday Night

Forecast today will start with a good chance of storms over the
far north, while lower chances central and south. Models bring
strong lift into western AR late in the morning, then gradually
move the lift and the cold front through AR Saturday afternoon,
evening and into the overnight. NAM remains the slowest compared
to the GFS and Euro, and will blend all three for overall
movement. Numerous showers and thunderstorms are expected as the
upper and surface system move through AR, with severe storms
possible. Damaging winds, large hail remain the primary threats,
but we will have shear in the atmosphere, and isolated tornadoes
will also be possible. The heavy rain potential will also be
present, with precip water values well over 1.5 inches to around
2+ inches in spots. A good area of widespread 2 to 5 inches of
rain will be seen, with the highest over northern to central AR,
the lowest amounts in southeast AR where 1 to 2 inches with
isolated higher amounts will be possible. Area rivers are coming
up due to the heavy rain over NW AR and southern MO, and rain on
Saturday to Sunday will only add to the flood potential. The cold
front is expected to reach eastern AR around sunrise on Sunday,
and continue to push the main area of convection east. Lighter
showers will still be possible behind the front through Sunday,
but generally end Sunday night, except possibly far northern AR
with some wrap around the surface low pressure. Temperatures will
be above normal today, then back to near normal values on Sunday.

&&

.LONG TERM...Monday Through Friday

The strong upper low will be over the Midwest to begin the long term
period. Northwest flow will be over Arkansas and will continue into
Tuesday. The upper trough makes its way to New England by Tuesday
night. A high amplitude upper ridge moves onto the west coast
Wednesday and an upper trough develops on the east side. This upper
trough moves through Arkansas Thursday and the ridge builds into the
state late Friday.

A warm front moves into Arkansas Wednesday. Expect small rain
chances Tuesday night then increasing on Wednesday. Low pressure
will bring a cold front through the state Wednesday afternoon and
night enhancing the chances of showers and thunderstorms. Rain
chances decrease on Thursday as high pressure builds over the area
and continues through Friday.

Temperatures through the period will be mainly below normal. The
warmest day should be Tuesday with temperatures reaching the lower
70s to lower 80s.

&&

.PRELIMINARY POINT TEMPS/POPS...
Batesville AR     81  67  72  47 /  60  90  90  10
Camden AR         85  66  72  48 /  60  90  60  10
Harrison AR       78  62  65  43 /  90  90  70  10
Hot Springs AR    81  64  69  47 /  70  90  60  10
Little Rock   AR  84  68  72  48 /  60  90  80  10
Monticello AR     88  70  73  51 /  40  80  90  10
Mount Ida AR      79  61  67  45 /  80  90  50  10
Mountain Home AR  77  66  69  44 /  80  90  80  10
Newport AR        84  69  73  49 /  40  90  90  10
Pine Bluff AR     85  69  72  50 /  50  80  80  10
Russellville AR   80  65  69  45 /  80  90  70  10
Searcy AR         83  68  73  48 /  50  90  90  10
Stuttgart AR      86  70  74  50 /  40  80  90  10
&&

.LZK Watches/Warnings/Advisories...
Lake Wind Advisory from 9 AM this morning to 9 PM CDT Sunday FOR
Arkansas-Bradley-Calhoun-Clark-Cleburne-Cleveland-Dallas-Desha-
Drew-Faulkner-Garland-Grant-Hot Spring-Independence-Jackson-
Jefferson-Lincoln-Lonoke-Monroe-Ouachita-Prairie-Pulaski-Saline-
Sharp-White-Woodruff.

Flash Flood Watch through Sunday evening FOR Arkansas-Baxter-
Boone-Clark-Cleburne-Conway-Dallas-Faulkner-Fulton-Garland-Grant-
Hot Spring-Independence-Izard-Jackson-Jefferson-Johnson-Logan-
Lonoke-Marion-Monroe-Montgomery-Newton-Perry-Pike-Polk-Pope-
Prairie-Pulaski-Saline-Scott-Searcy-Sharp-Stone-Van Buren-White-
Woodruff-Yell.

&&

Short term and aviation...59 / Long term...51

Hazardous Weather Outlook
National Weather Service Little Rock AR
505 AM CDT Sat Apr 29 2017

ARZ003>007-012>016-021>025-030>034-037>047-052>057-062>069-301015-
Boone-Marion-Baxter-Fulton-Sharp-Newton-Searcy-Stone-Izard-
Independence-Johnson-Pope-Van Buren-Cleburne-Jackson-Logan-Conway-
Faulkner-White-Woodruff-Scott-Yell-Perry-Polk-Montgomery-Garland-
Saline-Pulaski-Lonoke-Prairie-Monroe-Pike-Clark-Hot Spring-Grant-
Jefferson-Arkansas-Dallas-Cleveland-Lincoln-Desha-Ouachita-
Calhoun-Bradley-Drew-
505 AM CDT Sat Apr 29 2017

This Hazardous Weather Outlook is for a Large Part of Arkansas.

.DAY ONE...Today and Tonight

Isolated to scattered severe storms will be possible today and
tonight over much of Arkansas, as a frontal boundary and upper
level system move through the region. This morning mainly an
isolated strong to severe storm may be seen over northern
Arkansas, with damaging winds and large hail the main factors.
Later Saturday, the upper system and cold front gradually move
across Arkansas, and additional strong to severe thunderstorms
will develop later this afternoon, evening and into the overnight
hours. Damaging winds, large hail and isolated tornadoes will be
possible with the system and cold front.

Also, moisture levels will increased significantly and very heavy
rain will be seen, especially over western to northern areas of
Arkansas. A bit less over central and southern areas. Rain amounts
of 3 to 6 inches with isolated higher amounts will be possible
today and tonight over northern areas, while 1 to 3 inches with a
few isolated higher amounts will be seen over central and southern
areas. These heavy rain amounts will lead to flash and river
flooding over many parts of Arkansas. Residents need to follow the
latest statements and possible warnings during this dangerous
weather situation.

A flash flood watch is in effect for the expected heavy rain,
while winds will be elevated over mainly the eastern half of
Arkansas, and a lake wind advisory is in effect.

.DAYS TWO THROUGH SEVEN...Sunday Through Friday

A line of thunderstorms should be exiting eastern Arkansas Sunday
morning. Any severe thunderstorms will quickly weaken or move out of
the area. The main severe threats would be damaging winds or large
hail. Drier air moves into the state in the afternoon diminishing
rain chances.

The next system will arrive with a warm front Wednesday. Chances of
showers and thunderstorms are expected Tuesday night continuing into
Thursday. Severe thunderstorms are not expected with this system at
this time.

.Spotter Information Statement...

Spotter activation may be needed later today through early
Sunday. Please monitor the latest forecasts over the next couple
of days.

&&

Visit NWS Little Rock on the web. Go to http://weather.gov/lzk.

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