Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Little Rock Arkansas
640 am CDT Friday may 22 2015
Aviation...22/12z taf cycle
Expect VFR conds to continue across the forecast area through the period. Middle and high level
clouds will continue to increases as the period progresses. Surface high pressure is
expected to hold in place across the forecast area today...then gradually shift
eastward tonight. Some low level moisture will begin to advect northward into parts
of northern and western at later tonight. Mentioned vcsh for northern Arkansas late tonight...
but the majority of rainfall shld remain to the north and west of Arkansas through
Previous discussion... /issued 353 am CDT Friday may 22 2015/
Short term...today through Monday night
Today...decreased probability of precipitation across the state with hires models continuing
to both slow down...and diminish precipitation before it reaches the
state. The main concern is that the current setup is fairly similar
to what was seen with heavy rain two weeks ago...and those systems
that developed in Oklahoma did not diminish before producing heavy
rain across Arkansas. Similarly...the models did show those
weakening before reaching the state. Although despite these
concerns...do believe the dry air and high pressure...both at the
surface and aloft over the state will keep widespread precipitation
from making it into the state.
High pressure will depart to the east on Saturday and bring a return
of moist southerly flow to the state. This deep moisture will
increase dewpoints by over 20 degrees with readings in the 70s
across portions of western Arkansas.
Otherwise...the main focus of the forecast is the potential for
heavy rainfall during the Holiday weekend. Backed off on both probability of precipitation
and quantitative precipitation forecast with best chances for precipitation holding off until
Sunday. However...it does continue to look that the potential for
heavy rain will be on Sunday and into Monday. The GFS continues to
be the most aggressive with quantitative precipitation forecast amounts. Precipitable water amounts
will be in the 1.5 to over 2 inch range...so do expect this to be a
big rain maker in the state...and leaned towards the GFS with quantitative precipitation forecast
amounts. Models are in agreement that the heaviest of the rain will
be in place across Oklahoma and Texas. At this point...do agree with
the timing and placement of the current Flash Flood Watch and will
not make any changes to it. Sunday afternoon and evening will see
the heaviest precipitation across western Arkansas where a quick one
to two inches will be possible. This combined with the heavy rain
expected upstream across Oklahoma will definitely lead to not only
flash flooding potential...but river flooding as well.
Models do differ a bit at holding on to the rain on Monday with the
European model (ecmwf) a bit slower. Again did lean towards the GFS and Gem and
decrease probability of precipitation a bit quicker. However...precipitation will remain in
the forecast for the remainder of the short term and continue into
the long term.
Long term...Tuesday through Thursday
Unsettled weather conds will continue on Tuesday and much of Wednesday as yet another upper
level storm system moves through the region. Locally heavy rainfall will continue to
be a concern and will only enhance the flooding potential over the forecast area.
The latest model solutions continue to indicate that the upper pattern will Delaware-
amplify during the latter half of next week. This will allow an upper ridge
to build into the mid-south...resulting in drier and warmer conds.
Convective trends by this timeframe will be more on the order of scattered
afternoon and early evening activity.
Flash Flood Watch from Sunday afternoon through Monday morning