Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 241733 AAB
AFDLZK

Area Forecast Discussion...UPDATED
National Weather Service Little Rock AR
1233 PM CDT Wed Apr 24 2019

.DISCUSSION...

Updated to include the 18Z aviation discussion below...

&&

.AVIATION...

Scattered SHRA and a few TSRA will remain possible across the
area...with best chances across the WRN/NWRN areas for this
afternoon. Expect the coverage to increase some overnight and
effect areas further SE. Some MVFR or lower conditions will be
possible with this activity. No widespread improvements are
expected until beyond this TAF period.

&&

PREV DISCUSSION...(ISSUED 354 AM CDT Wed Apr 24 2019)

SHORT TERM...Today Through Thursday Night

A large closed upper low remains across northwestern Mexico this
morning with pressure falls noted across northeastern Mexico. A
rather diffuse surface pressure trough extends northeast from this
feature, coincident with a quasi- stationary frontal boundary
draped across far northwestern AR.

Objective analysis shows a plume of enhanced moisture in the
surface to H700 layer residing within the frontal zone across
western sections. Continued synoptic ascent ahead of the upper
low and atop the frontal surface, combined with this sustained
low- level moisture advection, remains supportive of showers
across extreme western and northwestern portions of the area. A
pool of MLCAPE on the order of 500 J/kg has proved sufficient for
embedded thunder as well with lightning noted in the stronger
cells.

Through today, not much change is expected with the position of
the front, although some wobbling is possible. The greatest
probability of rain and thunder will remain across roughly the
northwestern half of the area through evening where frontal
forcing is maximized within the broader regime of synoptic forcing
for ascent. By late evening into tonight, the upper low will begin
ejecting northeast with a rapidly-developing surface cyclone
immediately ahead of the upper low.

Rainfall should increase in coverage overnight into Thursday
morning as upper dynamics associated with the approaching trough
become more pronounced. Precip will be maximized within an area
of deformation invof the surface front and poleward of the
surface low as it pushes into the area. An additional maxima in
precip is expected within a more thermodynamically unstable
region to the east of the low track. Maximum storm total QPF on
the order of 1 to 1.5 inches seems well-placed stretching
southwest- to- northeast across the state with isolated higher
amounts expected in thunderstorms. Given antecedent soil moisture
conditions, localized flooding will be possible, although a
widespread and high-impact threat does not appear likely. Severe
weather is also not expected.

Through the day Thursday, the upper low and surface cyclone will
slowly push across southern portions of the area with continued rainfall
and embedded thunder. Another upper trough to our north will
quickly drop towards the mid Mississippi Valley late Thursday and
encourage the slower-moving system affecting our area to finally
eject east. Precip will diminish west-to-east before dawn on
Friday.

Highs temperatures will be near to slightly above average through
the period with lows remaining above average. As a cooler and
drier air mass begins to filter in late Thursday, expecting lows
to become more seasonal with low-50s to near 60 F Thursday night.

LONG TERM...Friday Through Tuesday

At the onset of the period, surface high pressure will be moving
eastward through the region on quasi-zonal flow aloft. Winds will
come back around to the south, with temperatures warming back into
the 80s on Saturday ahead of an approaching cold front.

The front itself will move into the region during the day Saturday.
There could be some showers/storms with it, but with the lack of
deep-layer moisture return ahead of it and lack of upper level
support, wouldn`t expect much more than isolated coverage at the
most.

The boundary will stall out or wash out near southern Arkansas/
northern Louisiana as it hits nearly parallel upper flow by Sunday.
High pressure will quickly move through the region, with return flow
setting up early next week ahead of the next system.

Upper ridging will shift toward the southeast conus early to mid
week next week, with troughing developing over the west. As a
result, expect deeper moisture return. As a result, rain chances
will ramp up with this next front as it begins to affect Arkansas
just beyond the end of the period.

&&

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

$$

Aviation...62


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