Area forecast discussion...updated
National Weather Service Little Rock Arkansas
1237 am CDT Monday may 20 2013
Discussion...
Updated to include the 06z aviation discussion below...
&&
Aviation...
Breezy srly winds will persist through much of the period as surface
pressure gradient remains tight across the region. Have mentioned
thunderstorms in the vicinity across northern sites during the next few hours as the activity to
the west moves closer to these terminals. Otherwise...some MVFR
ceilings could be seen overnight at many sites as moisture streams
north. Conditions will improve for Monday daytime for most sites. Do
continue to mention prob30 for thunderstorms and rain during the midday to evening
hours on Monday across the northern sites as storm system to the west moves
closer. Some strong to severe storm could be seen.
&&
Previous discussion... /issued 247 PM CDT sun may 19 2013/
Short term...tonight through Wednesday night
Its going to be a rather active setup over the duration of the
short term periods. A frontal boundary currently extends from
Nebraska down into West Texas. In the upper levels...however...
the flow is nearly parallel to the surface winds...which is
somewhat impeding the progress of the cold front.
Over the next few days...several waves will move out ahead of the
front in the mean flow...and interact with the boundary. This will
allow for several rounds of showers and thunderstorms in an mesoscale convective system-
type synoptic setup for our area.
First system will likely develop in southern Kansas/northern
Oklahoma late tonight...with the heaviest activity likely
narrowly missing northern Arkansas on Monday morning. However...
some storms will be possible late in the night/early Monday
morning...and a strong storm or two is not unexpected.
However...what concerns ME is the remnants from tonights expected
system...more specifically an mesoscale convective vortex. If sufficient surface-based
heating can occur on Monday...this should be more than enough
needed to generate showers/storms as the feature moves through the
area. Forecast soundings do show a great deal of instability
available...and this would be the triggering mechanism needed.
Any storms that develop during the day Monday would have the
necessary ingredients to become strong to severe...with hail and
wind threats. Another concern will be heavy rainfall...given
extremely slow low level storm motion...and precipitable water
from 1.50 to 1.75 inches.
Any storms that develop during the day Monday will diminish in the
hours after sunset Monday night. However...attention will then
shift back to the west...where storm initiation will likely occur
close to the front as the low level jet kicks in. This next mesoscale convective system
and the associated frontal boundary will move in to Arkansas after
midnight Tuesday morning...with showers/storms becoming likely.
Strong to severe storms will be possible...mainly after midnight.
Again...there will be a hail and wind threat...as well as locally
heavy rainfall. Low level directional shear is not that great...
which would act to limit any tornado threat.
Storms may diminish a little bit during the day Tuesday as the
front slows down over the state. With cloud cover present...
there will likely be a bit of a capping inversion ahead of the
front which would initially stymie convection during the
afternoon. However...a strong upper level trough expected to move
out of the southern rockies...and should act to overcome any
inhibitions on Tuesday afternoon and evening...allowing for
additional shower and thunderstorm development...primarily ahead
of the front over central and southern Arkansas.
Activity will diminish during the day Wednesday...as the storm
system moves out of the region. However...on Wednesday
night...models are now starting to show another wave moving in
from the northwest...which would act to bring additional
showers/storms late in the period and just beyond.
Throughout the short term...temperatures will mostly be above
seasonal averages...but will ultimately determined by cloud cover
and rain-cooled air...especially on Tuesday.
Long term...Thursday through Sunday
A frontal boundary is expected to be sagging into the area on
Thursday as the upper trough will be moving across the Great Lakes
region. Will keep a slight chance of showers/storms in the
forecast but overall coverage and rain amounts may be low. On
Friday the boundary is expected to be weakening while some upper
northwest flow may send some upper energy into the area. Have kept a
slight chance of convection going...but this may be lowered with
later forecasts. On Saturday a surface and upper ridge build move
over the area and the chance of rain drops. This holds into
Sunday. Temperatures will be near normal values to a bit above
through the period.
&&
Preliminary point temps/pops...
Batesville Arkansas 69 80 64 83 / 50 70 70 40
Camden Arkansas 70 87 66 82 / 30 40 60 50
Harrison Arkansas 66 81 59 78 / 70 60 50 20
Hot Springs Arkansas 72 82 66 82 / 50 60 70 40
Little Rock Arkansas 71 84 67 80 / 40 60 60 40
Monticello Arkansas 72 87 68 82 / 30 30 60 50
Mount Ida Arkansas 71 81 62 81 / 50 60 70 30
Mountain Home Arkansas 67 82 60 79 / 60 70 60 20
Newport Arkansas 70 82 66 83 / 50 70 70 40
Pine Bluff Arkansas 71 86 67 82 / 40 40 60 50
Russellville Arkansas 69 81 61 80 / 50 70 60 30
Searcy Arkansas 68 83 63 82 / 50 60 70 40
Stuttgart Arkansas 71 84 67 83 / 40 50 60 50
&&
Lzk watches/warnings/advisories...none.
&&
$$
Aviation...62
