Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Little Rock Arkansas
656 am CDT Wednesday Jul 23 2014
Updated for the 12z aviation discussion below.
Models are not handling the evolution of convection to the north
of Arkansas well at all. Storms have loosely formed along a
boundary this morning...stretching from just north of Poplar Bluff
Missouri off to the northeast. It is unclear at this time whether
this will continue to back build to the southwest...thus possibly
leaving northern taf sites free of convection today and affecting
central and southern sites...or whether high resolution models
will eventually be correct and we will see convection in the
northwest half of the state later on. Have stayed the course for
the time being...advertising thunderstorms in the vicinity at northern sites after 18z...and
leaving others void of any mention of convection. Confidence in
where convection will eventually occur...and how widespread it
will be...is not very high at the moment. Expect there will be
storms around through the day...just do not know which terminals
they will affect at this time.
Otherwise VFR conditions are expected through the period with
winds gradually veering to a northerly or northeasterly direction
after 00z this evening.
Previous discussion... /issued 333 am CDT Wednesday Jul 23 2014/
Today through Saturday night...
weather will continue to be fairly active across the region this
period as upper pattern remains highly amplified. High res models
continue to show widespread precipitation along an advancing cold
front this morning but current radar/satellite trends have yet to
show any deep convection thanks mainly to warmer temperatures aloft.
Will not totally discount these models but probability of precipitation have been lowered
due to lack of any activity at this time.
Latest moisture channel imagery shows the major players quite
clearly this morning. Sprawling upper level ridge remains centered
over Colorado with another anti-cyclone over the western Atlantic.
In between these highs is eastern Continental U.S. Troughing with weak upper
low that will meander around the Gulf Coast with a much stronger
upper low just now approaching the Washington state coast. Upper low
will flatten the western ridge just enough to allow the previously
mentioned cold front...currently over southern Missouri...to move to
Front is expected to pass through the state today with only slight
chance to low end chances of precipitation. After another hot day
today...the front is expected to stall over the southwest on
Thursday which will bring a brief break from the Summer heat and
humidity. Boundary will lift back to the north on Friday as western
ridge expands to the east with a return to more typical Summer
weather. Upper ridge will then dominate through the remainder of the
period with a continuation of hot and generally dry conditions.
Long term...Sunday through Tuesday
for several days now the models have been hinting at a pattern
change as we head into the weekend...and this continues to be the
case this morning. An upper low...set to move onshore in the Pacific northwest
today...will have contributed to a large upper trough carving out a
place across the Great Lakes region by Sunday evening. Upper level
flow will further amplify heading into next week...firmly
establishing a northwest upper flow across Arkansas and leading to
cooler than normal conditions to round out July.
Temperatures will be right around normal on Sunday...with low to middle
90s forecast statewide. Developing northwest upper flow aloft and
supporting upper trough over eastern Continental U.S. Will drive a front into the
state sometime Sunday...most likely sun evening. Right now models
are not too keen on precipitation chances...but have some slight chance
probability of precipitation in the NE Sunday afternoon and evening...followed by
broad-brushed slight chance probability of precipitation Sunday night and Monday morning.
Expect there will be at least some isolated to scattered showers and
thunderstorms accompany the front. The incoming air mass will not be
as unseasonably cool as the one from late last week...but it will
have a push from Canadian high pressure to our north and it will
also definitely be drier and cooler than normal. MOS guidance
supports this scenario...already showing temperatures 4-5 degrees below
climatology at days 6 and 7...a significant amount given climatology bias that
far out. As such...by Tuesday...highs should top out only in the middle 80s
for most locations.
Preliminary point temps/pops...
Batesville Arkansas 91 67 84 64 / 40 10 10 0
Camden Arkansas 94 72 92 68 / 20 20 20 10
Harrison Arkansas 91 66 87 65 / 40 10 10 0
Hot Springs Arkansas 93 72 91 68 / 30 10 10 0
Little Rock Arkansas 92 72 88 67 / 30 20 10 0
Monticello Arkansas 94 71 91 67 / 20 20 20 10
Mount Ida Arkansas 93 68 91 68 / 30 10 10 0
Mountain Home Arkansas 90 67 85 64 / 40 10 10 0
Newport Arkansas 91 67 84 64 / 40 10 10 0
Pine Bluff Arkansas 93 71 90 68 / 20 10 20 0
Russellville Arkansas 92 71 88 67 / 40 10 10 0
Searcy Arkansas 91 70 86 66 / 40 10 10 0
Stuttgart Arkansas 92 71 87 66 / 30 20 10 0