Severe Thunderstorm Warning 340, NWS Little Rock, AR

Area Forecast Discussion...UPDATED
National Weather Service Little Rock AR
607 PM CDT Tue Aug 7 2018

.AVIATION...00Z Forecast Cycle
Overall, VFR conditions will be prevalent. However, visibility
and ceilings could be restricted temporarily during storms. With
scattered showers/storms expected through the end of the period,
opted to go with VCTS/VCSH in the terminals where appropriate.
Sustained winds will largely be out of the south to west at less
than ten knots. TAFS out shortly.
&&

.PREV DISCUSSION...(ISSUED 306 PM CDT Tue Aug 7 2018)
SHORT TERM...Tonight Through Thursday

Zonal flow in place aloft along and to the north of the state this
afternoon, with elongated ridging remaining just to the south. An
impulse in the flow was making its way just north of the area and
was helping to provide lift for shower and thunderstorm
development across northern Arkansas this afternoon. With high
pressure in control to the south, only scattered cumulus had
developed and temperatures were quite warm by 20z, in the mid 90s
for many areas.

Through the short term portion of the forecast, the zonal flow will
give way to more amplified troughing as ridging across the west
intensifies. This will allow additional pieces of shortwave
energy to pass over the state. Additionally, a surface boundary
will make its way into the state and will stall, helping to focus
activity locally. With persistent disturbances traversing the
flow and the boundary in place at the surface, widespread cloud
cover and increased rain chances will be advertised in the
forecast. This will lead to below normal daytime highs.

Deep southwesterly moisture flow continues to be seen with today's
12z model guidance as atmospheric profiles continue to be well
saturated. The latest data suggests PWAT values aoa 2" across much
of the state through at least the next 48 hours, which helps
support the idea of locally heavy although largely beneficial
rainfall. Sluggish storm motion and weak shear aloft combined
with sufficient CAPE values across the area further contribute to
the idea of heavy rainfall. Ultimately, timing of individual
disturbances as well as frontal position will dictate where the
axis of heaviest rainfall sets up. At this time, that looks to be
over portions of southwest to south central Arkansas.

LONG TERM...Thursday Night Through Tuesday

The pattern will remain unsettled in the extended period.
Looking aloft, an amplified ridge will be noted over the
western United States. A trough will extend from the Great
Lakes to the mid-Mississippi Valley and southern Plains.
The trough will slowly pivot to the north/east, with chances of
showers/thunderstorms ahead of the trough.

Toward the weekend, the trough/low pressure aloft will exit toward
the Ohio Valley. Ridging will occur over the southeast states,
including Arkansas, as the trough leaves. As the period comes to
a close, a new cutoff low may form to the west of the state, and
will head this way.

Given the pattern, rain chances in Arkansas will be mainly over
the southeast half of the state to begin the period. Precipitation
will tend to wind down by Saturday as the low kicks out, but will
return late in the weekend/early next week as the new low emerges.

For the most part, not looking at widespread heavy rain in the
long term. However, heavy downpours could result in localized
flooding in spots. Precipitation coverage will be more than the
usual this time of year.

As far as temperatures, daytime readings will be below average, and
close to average at night.
&&

.LZK Watches/Warnings/Advisories...NONE.
&&

Aviation...57