Area Forecast Discussion
Issued by NWS Little Rock, AR

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043
FXUS64 KLZK 220526 AAC
AFDLZK

Area Forecast Discussion...Update
National Weather Service Little Rock AR
1130 PM CST Sat Jan 21 2017

.Aviation...

Overall VFR flight conditions with ceilings will start the forecast.
Areas of MVFR with showers and isolated thunderstorms will be seen
overnight as the upper and surface storm systems affect AR. A break
in the storms will be seen early over the southwest to central AR,
then redevelop later overnight. Winds will be east to southeast at 5
to 15 mph, becoming more south to southwest at 5 to 15 mph over the
south toward Sunday morning, while becoming northeast to north at 5
to 15 mph over northern AR. Some patchy wind shear may be seen
mainly in southern AR, but not widespread enough to include in Tafs.
(59)

&&

.Prev Discussion.../ Issued 840 PM CST Sat Jan 21 2017
.Discussion...

Overall forecast on track. Evening convection continues over west to
south to central AR with movement to the north-northeast. In CWA
have seen mainly wind and hail with a few severe storms over
southern AR to parts of west. Will allow the tornado watch over
southwest to parts of central AR to expire at 9 PM, while the
tornado watch over parts of southeast AR will continue to 3 am
Sunday. Short range models move the shortwave energy this evening
through AR around 10pm to midnight, but then as the upper low
pressure rotates from the west over TX and OK, additional convection
with isolated strong to severe will be possible mainly over southern
AR. Lighter rain and showers over central to northern AR overnight
to Sunday. The main rain should be pushing east Sunday afternoon.
Otherwise, lows tonight will be from the upper 40s to 50s. (59)

&&

.Prev Discussion.../ Issued 227 PM CST Sat Jan 21 2017/
.Short term...Tonight through Monday night.

Short term models are in decent enough agreement at this point in
time that a general consensus will be adopted. The one solution
that is the outlier is the NAM and its solution will not be weighted
nearly as much as the remainder of the models. All signs continue to
point to a possible severe weather episode this evening and over
night.

Southerly flow has helped warm temperatures into the 60s and also
continues to advect moisture into the region with dew points in the
upper 50s everywhere except the NW corner of the state. Shortwave
located well to our east at this time is producing widespread severe
weather over the southeast conus but has provided just enough
subsidence to keep convection in check at this time. Showers and
thunderstorms are expected to erupt later this afternoon.

Primary shortwave clearly seen on moisture channel imagery this
afternoon over west Texas. All high res models have convection
initiation over far east Texas late this afternoon and spreading
into the state with time. Meanwhile a frontal boundary that has been
stalled out along the gulf coast will be lifting to the north as a
warm front with low pressure developing on it.

Aforementioned shortwave trough will kick out and take on a negative
tilt as it approaches. Low pressure is forecast to cut off in its
base and move across the southern plains and across Arkansas tonight
and early Sunday. Strong to severe storms are possible, with the
greatest threat during the overnight hours.

Data continues to show steep lapse rates, cold temperatures aloft
which will be favorable for large hail formation. In addition enough
wind shear is present that a damaging wind and tornado threat can not
be discounted but current thinking is hail, perhaps greater than two
inches in diameter, is the primary severe threat.

Come early Sunday, storms could consolidate into more of a linear
mode over eastern Arkansas as the associated cold front pushes
through. Upper trough/low will still have to cross the state Sunday
and with moisture wrapping around it, precipitation chances will
continue. As cold pool passes overhead, the possibility of hail will
exist in any stronger storms but should be small and sub severe.

Any lingering precipitation should move out of Arkansas during the
evening Sunday, as the upper low moves into the Ohio Valley with
upper ridging and quiet weather expected for Monday. Temperatures
will continue to be above normal through the period.
&&

.Long Term...Tuesday through Friday Night

By 12Z Tuesday Arkansas will be enjoying dry and mild conditions as
a result of weak 5H ridging. Another huge upper trough will be
carved out across the western US. The associated surface low is
projected to move northeast out of the central plains and remain
well north of AR. Once the low moves off to the NE, the upper
pattern will change with some semblance of an omega block off the
west coast allowing for strong and dry northerly 5H flow into the
area. This will be a pattern that is likely to persist for several
days and bring dry and chilly weather to the region. The first in a
series of cold fronts will move through the state this week starting
with Tue night, with reinforcing cold fronts anticipated Friday
night and Sat night.

After a very mild Tuesday, temps will be cooler Wed and then even
cooler on Thu. At or below normal temps are expected Thu through the
weekend.
&&

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

$$

Short Term...56 / Long Term...32



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