Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 210029
AFDLZK

Area Forecast Discussion
National Weather Service Little Rock AR
629 PM CST Mon Feb 20 2017

.AVIATION...21/00Z TAF CYCLE

Rain wl cont to overspread the area tngt ahead of upr lvl storm
system. VFR conds at the start of the PD, with conds falling to
MVFR levels, OCNL IFR, as more persistent area of rain moves in.
Overall coverage of the rain wl sloly diminish from the W late
tngt and Tue as a Pacific CDFNT moves thru the FA. An assocd upr
lvl low pres system wl linger ovr the region on Tue, with spotty
showers and low clouds expected. /44/
&&

.PREV DISCUSSION...(ISSUED 231 PM CST Mon Feb 20 2017)

SHORT TERM...Tonight Through Wednesday

Early afternoon water vapor satellite imagery showed a long and
sharp trough extending from northern Nebraska south to deep south
Texas moving slowly east towards Arkansas. Surface observations
showed a spring-like weather pattern in place across Arkansas with
temperatures in the 70s and dew points in the lower 60s for most
areas. To the west of the upper trough...a Pacific-type cold front
was moving quickly to the east across the middle of the Central
Plains. While air behind this front is not much cooler...it is
significantly drier.

Through tonight...as the upper trough approaches Arkansas...it
will bring increasing large scale forcing for ascent across the
state. With ample low-level moisture already in place...the strong
lift should result in widespread rain showers and isolated
thunderstorms developing from southwest to northeast from sunset
through the overnight hours.

The 12Z RAOB did not show any steep lapse rates aloft over
central Arkansas...and with the upper trough approaching at a
neutral tilt...do not expect significant upper level cooling to
outpace convection limiting the available potential energy for
thunderstorm updrafts through tonight. As a result...think that
the threat for severe storms is low across Arkansas. Will keep a
close eye on storms throughout the night though as strong lift in
the relatively dry air aloft will serve to steepen up lapse rates
a bit allowing for a quick pulse type strong thunderstorm. Threats
from storms are expected to be limited to small hail, strong wind
gusts and cloud to ground lightning.

Rainfall totals are expected to remain below 1 inch for most of
the state. Isolated higher amounts are possible...but the threat
for widespread flooding appears to be low.

Tuesday...Rain chances will continue across Arkansas Tuesday
morning...but will diminish from northwest to southeast from late
Tuesday morning through the afternoon hours as the Pacific-type
cold front filters drier air across the state. Despite the passage
of a cold front...temperatures are expected to remain well above
normal with highs topping out in the lower 70s late in the
afternoon.

Tuesday night through Wednesday...Large scale forcing for
subsidence will be in place over the region during this time with
upper level ridging over Arkansas. This will allow for continued
above normal temperatures and mostly sunny/clear skies through
Wednesday afternoon.

LONG TERM...Wednesday Night Through Monday

In the long term, the zonal flow aloft continues along with
southerly flow at the surface, so warming trend continues. A broad
5H trof takes shape across the central US Thu and Fri. The
accompanying surface low will track NE and well north of the state,
but will drag a cold front through the area late Friday. With the
system dynamics north of the area along with a capping SW flow
aloft, precip chances with the cold front Fri look very slim.
Therefore, I removed the inherited slight chance pops across the
east for Friday afternoon. Another cold front and upper low will
bring a somewhat better chance for rain Sunday night through
Tuesday. Models diverge considerably in regards to timing and
strength of this system, so while the window of rainfall opportunity
is fairly long, the chances for significant rain remain low.

After near or actualized record breaking warmth for much of the
week, it will turn noticeably cooler with the frontal passage on
Friday. High temps Sat in the 50s before a gradual warm up begins
Sunday into early next week. Clouds and precip may keep temps from
warming too fast on Monday with 60s in the forecast. Sat night looks
to be the coldest night of the extended with temps dipping into the
30s statewide. Still not bad for Feb.
&&

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

$$



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