Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Little Rock Arkansas
500 am CST Thursday Dec 18 2014
Updated to include the 12z aviation discussion below...
Much of the widespread precipitation is over the southeastern half of the state
this morning...and will gradually shift east later this morning.
Conditions under this rainfall have ranged from MVFR to as low as
LIFR in some spots. Behind the exiting rainfall...areas of dz and
low ceilings will be seen...with MVFR to LIFR conditions possible
through much of the day. Some improvements may be seen this
afternoon...but likely see MVFR conditions persist at most
terminals. Some fog and dz will continue to be possible overnight
into Friday...with no significant flight condition improvements
expected until beyond this taf period.
Previous discussion... /issued 223 am CST Thursday Dec 18 2014/
Short term...today through Sunday night
Rain continues over much of the area this morning...with pockets
of sleet mixed in in the west...north and central. Precipitation
will taper off later this morning...as the upper wave responsible
for it moves northeast and away from the state. Another upper
system passing north of the region will keep small precipitation
chances in the north. No appreciable accumulation is expected from
any wintry precipitation that falls.
Late tonight...surface low pressure will develop along the Gulf
Coast. At the same time...an upper trough will move into the
Southern Plains. Uplift associated with the surface low will send
Gulf moisture into the region...with Pacific moisture from the
upper system moving in as well. With this...precipitation is
expected to become widespread again in at least central and
southern Arkansas Friday morning.
By Friday night...the surface low should be around the central
Gulf Coast region...with drier air filtering in behind it.
Precipitation is expected to come to an end during the morning
hours on Saturday. Forecast sounding data does suggest a mix with
or brief changeover to sleet in the north and possibly west before
ending. However...this is expected to be of little consequence.
High pressure will follow this system...but by late Sunday...it
will move east ahead of the next approaching system.
Long term...Monday through Wednesday
A larger scale upper trough will be deepening over the central
Continental U.S. At the start of the long term period...with a quick moving
upper wave moving southeast over Arkansas. This wave will bring a cold front
south into the state...with precipitation chances expected Monday into Monday
night. Another surge of colder air will be seen Tuesday into Wednesday as
another upper wave moves across the region. This second wave will
erode much of the moisture as it moves through...with precipitation
chances low for the end of the forecast. Latest indications are
that most of the moisture will be out of the state before the
coldest air arrives. As a result...keep precipitation mostly in the
liquid form for most locations. However...there could be a brief
switch over period just before the moisture exits Tuesday night. As
stated in previous discussions... significant uncertainty remains
on when the coldest air arrives and when the moisture will exit.
These uncertainties will become more clear in the coming
days...and so with the potential for any wintry precipitation early next
Preliminary point temps/pops...
Batesville Arkansas 40 35 42 32 / 20 10 50 40
Camden Arkansas 47 42 47 37 / 40 30 80 60
Harrison Arkansas 42 34 41 31 / 30 10 30 20
Hot Springs Arkansas 45 40 45 34 / 30 20 70 50
Little Rock Arkansas 44 39 45 35 / 30 20 70 60
Monticello Arkansas 47 41 47 37 / 40 20 80 80
Mount Ida Arkansas 44 38 45 33 / 20 20 70 50
Mountain Home Arkansas 41 35 41 31 / 30 10 30 30
Newport Arkansas 40 35 42 32 / 20 10 60 40
Pine Bluff Arkansas 45 39 45 36 / 30 20 70 70
Russellville Arkansas 47 39 45 34 / 20 20 50 40
Searcy Arkansas 44 35 43 33 / 20 10 60 60
Stuttgart Arkansas 43 38 45 35 / 30 10 70 70