Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 160512
AFDLZK

Area Forecast Discussion
National Weather Service Little Rock AR
1212 AM CDT Tue May 16 2017

.UPDATE...
Updated for 06z TAFs.
&&

.AVIATION...
For the 06z TAFs, VFR conditions are expected at all Terminals. Most
areas will remain mostly clear, but could see some mid to high level
clouds filter in during the overnight hours. Overall, wind speeds
will remain light, but on Tuesday are forecast to increase between
10 and 15 KTS. Higher gusts around 20 KTS are also expected as a low
pressure system approaches from the west and tightens the pressure
gradient. Thicker cloud cover should move into the State Tuesday
evening.

&&

.PREV DISCUSSION...(ISSUED 602 PM CDT Mon May 15 2017)

Short Term...Tonight through Wednesday...
Arkansas should have one more day of relatively nice weather before
the next system starts to bring rain chances to the area.

Surface high pressure over the southeast US will continue sliding
eastward tonight. Southerly winds will continue across the area
tomorrow, and surface dewpoints will continue to increase as deeper
Gulf moisture advects into the area.

A dryline / cold front will set up across the OK and TX panhandle
region tomorrow, and will start to move slowly eastward across the
plains, but its slow progress will prevent it from reaching into the
forecast area during the short term forecast period. As the surface
pressure gradient tightens ahead of this system, gusty winds will
likely prevail in a number of areas by late morning into the
afternoon hours tomorrow, and a lake wind advisory may be required.

Above the surface a ridge aloft will start to break down as a
vigorous shortwave embedded in a broad trof across the west starts
to take aim at the area. Swly flow will prevail aloft tomorrow, and
midlevel heights and temps will start to fall more appreciably by
tomorrow night. With cooling temps aloft and lowering heights
associated with the shortwave, and abundant low level moisture,
thunderstorms should develop in OK and some may move into the
western portions of the forecast area tomorrow night and on
Wednesday, while additional convection could develop on its own
across the forecast area.

The limiting factor on storms moving in from OK is that the upper
level flow will be southwesterly, with a southerly surface flow, so
if a squall line forms across the plains, I would not be surprised
if much of it breaks up as it moves eastward into the western
portions of the state. With that in mind, I have kept POPs at a
relatively modest level throughout the time frame.

Long Term...Wednesday Night through Monday...
A very unsettled pattern with a lot of uncertainty in the long
term periods. Although both the GFS and ECMWF are somewhat similar
with the general pattern, there is a lot of discrepancy in the
timing and strength of the systems as to how they may affect AR.
As we begin with the Wed night period, a fairly strong upper level
system will be entering the southern plains generating storms
across north Texas and OK. It appears that this system may move
northeast from that point, sparing the state from widespread
showers and storms, but still enough moisture and lift to generate
scattered activity Wed and Thu. In the wake of this system,
another larger and more potent upper low will take it`s place. A
cold front will also be approaching the western portions of the
state late Friday serving as a focus for showers and storms. The
GFS is still showing the potential for heavy rain Fri night and
Sat across the NW half of the state, while the ECMWF is slower and
keeps the heavy rainfall northwest of the state. This solution
would bring widely scattered activity across AR on Sat, but more
widespread rain chances on Sunday/Sun night and possibly lingering
into Mon. Meanwhile, the GFS brings an end to the rain early
Sunday. It appears the cold front will move through sometime Sat
or Sunday depending on which scenario is verified.

Long story, short, with the upper systems setting up to our west,
there will be an extended period of showers and thunderstorms from
Wed night through at least Sat and possibly into early Mon. The
potential exists for some heavy rainfall, exceeding two inches
mainly across NW AR, but confidence is very low at this point.
Hopefully, the models will become more consistent over the next
couple of runs, so stay tuned.

Temperatures will remain a bit above normal with increasing humidity
values through at least Friday with highs in the 80s and lows in the
60s. The aforementioned cold front should bring temps down a few
degrees and closer to normal by Sunday and Monday.

&&

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

$$


Aviation...Cross



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