Area Forecast Discussion
Issued by NWS Little Rock, AR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
000
FXUS64 KLZK 141028
AFDLZK

Area Forecast Discussion
National Weather Service Little Rock AR
428 AM CST Sun Jan 14 2018

.SHORT TERM...Today Through Tuesday

Short term will focus on chances for accumulating snow in
northern Arkansas today, and for central and southern parts of the
state Monday night into Tuesday.

First let`s discuss this morning`s snow. A PV anomaly located
roughly over the western NE/KS border this morning, will shift
southeastward towards Arkansas through the morning hours. Regional
radar trends have already shown an increase in returns, with
flurries or light snow being reported in northeast Oklahoma early
this morning and light to moderate snow showing up in observations
in central to eastern Kansas. This gives confidence that snow
will indeed shift southeast into northern Arkansas as the morning
progresses. The only uncertainty is exactly how much will
accumulate. Backed off on the totals just a tad from what the
evening shift had, though in reality it`s still in the ballpark.
Expect somewhere between half an inch to an inch of snow in the
north central part of the state or roughly in areas around and
north of a line from Harrison, to Marshall, to Mountain View, and
finally Salem. There is a possibility it could be upwards of an
inch near the MO border between Harrison and Mountain Home, but I
think this will probably be the exception to the rule.

Attention then turns to the possibility of widespread light snow
on Monday into Tuesday. The snow producing disturbance from this
morning will move east of the state by this afternoon or early
evening at the latest. However, another system will drop south
from Canada into the Upper Midwest early Monday, becoming a cutoff
low as it does so. An associated surface low will shift from the
northern plains to Wisconsin as a result, allowing a strong arctic
front to dive south through the plains and into Arkansas during
the late afternoon or early evening hours on Monday. Models are in
good agreement on the timing of the front, as well as the pre and
post frontal temperature trends; they are going to plummet into
the teens and 20s if you`re wondering. What is not well agreed
upon is how much moisture will be present as the front moves
through. Solutions range from mostly dry, to several inches of
snow Monday night into Tuesday. In general, one thing is clear and
that is that the dominant precipitation type for Monday night and
Tuesday will be snow. Surface flow is southerly on Monday, enough
for temperatures to be 5-10 degrees above the freezing mark,
however model soundings show that the low-level warm nose is
barely above freezing around and shortly after precipitation would
start. Between evaporative cooling and cold air advection, expect
that the only part of the profile above freezing during the
evening hours when precipitation onset occurs will be the near
surface layer. Thus expect rain will quickly transition to a
rain/snow mix then all snow between Monday evening and around
midnight Monday night most everywhere. The strongest intrusion of
"warm" air aloft will be in southwest Arkansas where perhaps a 1-3
hour window of snow/sleet mix as the surface based cold pool
deepens before the warm nose disappears Monday evening.

Regarding amounts, again the forecast is uncertain here. The
current forecast reflects 1-2 inches of snow accumulation roughly
south of areas like Mena, Mt Ida, Conway, Searcy, and Augusta. The
highest snowfall totals are likely to be within 15-20 miles
either side of a line from Texarkana to Pine Bluff and through De
Witt. Accumulations should around 2 inches in those areas. Decided
to hold off on issuing an advisory at this time. Uncertainty is
still fairly high, despite being only 36 hours or so from the
onset of wintry precipitation.

The event should wrap up Tuesday afternoon as strong high pressure
continues to slide south through the plains towards Arkansas,
shifting the frontal boundary south of the state and cutting off
precipitation.

&&

.LONG TERM...Tuesday Night Through Saturday

Period initiates with a highly amplified pattern sitting over the
CONUS with deep troughing over the eastern half of the nation with
an additional trough over the Pacific Northwest. Upper ridge between
these two systems will slowly progress eastward with time.

The models are in overall good agreement in the synoptic scale but
differ quite a bit with a southern stream system that will be
approaching the area Thursday. GFS solution remains much more
aggressive with this system versus its ECMWF counterpart. ECMWF
solution seems more realistic versus the GFS which has been quite
inconsistent over the past few nights and the forecast will be
trended in its direction.

Temperatures will be a bigger story during the period with Arctic
high pressure providing very cold conditions on Wednesday. The high
does move off to the east on Thursday for moderating temperatures
but even with a return to southerly winds, readings will remain
below normal.

Flow does flatten out later in the week and then turns to the SW as
the aforementioned trough in the Pacific Northwest digs into the
Rockies. This will allow temperatures to actually return to near
normal by the end of the period.

As the period ends, a storm system will intensify over the middle
part of the country, and will drag a new cold front toward the
region. Chances of showers will increase Saturday/Saturday night
but the air mass should be warm enough to support just liquid
precipitation.

&&

.PRELIMINARY POINT TEMPS/POPS...
Batesville AR     29  25  37  15 /  20   0  10  30
Camden AR         40  26  47  24 /   0   0   0  60
Harrison AR       32  26  31   8 /  30   0  30  20
Hot Springs AR    36  27  45  21 /  10   0  10  60
Little Rock   AR  34  27  42  21 /  10   0  10  50
Monticello AR     36  27  46  23 /  10   0   0  50
Mount Ida AR      38  26  44  19 /  10   0  10  60
Mountain Home AR  30  23  32   9 /  30   0  20  20
Newport AR        29  25  37  17 /  20   0  10  30
Pine Bluff AR     34  27  44  22 /  10   0   0  50
Russellville AR   36  27  40  18 /  20   0  10  50
Searcy AR         31  25  39  18 /  20   0  10  50
Stuttgart AR      32  27  42  21 /  10   0  10  50
&&

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

$$

Short Term...DALTON / Long Term...56



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.