Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Little Rock Arkansas
651 am CDT sun may 24 2015
Aviation...24/12z taf cycle
Scattered rain showers/thunderstorms and rain will be noted across the area this morning...along with
occasional stratus. This will result in mainly VFR/MVFR conds. Convection
will become more widespread across Arkansas this afternoon and tonight...with conds
deteriorating. Primarily expect MVFR conds by that time...with IFR
ceilings/visibilities where stronger storms occur. Breezy S/southeasterly surface winds will
also be common through much of the period. /44/
Previous discussion... /issued 443 am CDT sun may 24 2015/
Short term...today through Wednesday night
Showers and thunderstorms that brought widespread
rain...flooding...and a few tornadoes last night to Oklahoma has
continued its slow March eastward through the overnight hours. Have
begun to see showers and thunderstorms develop across the western
third of the state. WRF and hrrr disagree with how this system will
evolve over the next eight hours or so. The WRF shows the line of
showers and thunderstorms weakening around middle day...before
redeveloping after this evening. However...am leaning towards the
hrrr which shows showers and thunderstorms continuing to fall
through the day...as precipitation slowly pushes to the east. With
high preciptable water values around the state...these training
storms will be efficient rain makers with rain rates topping out at
1.5 inches per hour.
On top of everything...a breezy day can be expected today...with
sustained southeast winds of 15 to 25 miles per hour and gusts up to 35 miles per hour possible.
Did go ahead and issue a lake Wind Advisory through this evening.
Severe weather remains a possibility today as well. Midlevel lapse
rates are not fantastic...however cape values will be in excess of
1000 j per kg. With winds out of the southeast at the surface...helicity
values will be high enough to support a few tornadoes.
But by far the greatest threat will be the potential for flooding.
Over the past two weeks...portions of western Arkansas have seen
between 10 to 14 inches of rain...which is roughly 4 to 6 times
normal. Combine this with deep southerly flow and precipitable water
values between 1.5 to over 2 inches...which is 1 to 2 Standard
deviations above normal...and heavy rain and life threatening flash
flooding will be likely.
Continues to look like two rounds of heavy rain...with the first
round Sunday with two to four inches possible with the heaviest rain
across western Arkansas. Do expect there will be a lull in the
precipitation during the day on Monday before the second round of
heavy rain develops Monday night through middle day Tuesday. Models
have been consistent in showing a period of very heavy rain Monday
night. Again...do expect that another round of two to four inches
will be possible Monday night. As a result did go and issue and
extend the Flash Flood Watch to the entire area and go through 18z
Long term...Thursday through Saturday
Models indicate a weak upper ridge will set up along the MS River Valley late in
the week. With plenty of low level moisture remaining in place across the middle
south...scattered mainly diurnal convection can be expected each day. A
stronger upper level storm system is prognosticated to affect the late in the period.
Kept probability of precipitation in chance Cat this far in advance as changes in timing/strength
are likely with this system with later model runs.
lake Wind Advisory from 11 am this morning to 9 PM CDT this
evening for Arkansas-Baxter-Boone-Bradley-Calhoun-Clark-Cleburne-
Flash Flood Watch from 1 PM CDT this afternoon through Tuesday
afternoon for Arkansas-Baxter-Boone-Bradley-Calhoun-Clark-