Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Little Rock Arkansas
608 am CDT Thursday Aug 21 2014
stratus has developed across west central Arkansas and northern
Louisiana. Have tempo MVFR conditions through 15z. Southwest winds
will increase later this morning...and with higher gusts. Winds
and clouds will decrease with sunset.
Previous discussion... /issued 344 am CDT Thursday Aug 21 2014/
Main concerns this forecast cycle are warming temperatures with
corresponding heat index values. Due to heat and humidity a Special
Weather Statement will be issued to a possible heat advisory
being issued through the next several days. Finally overall
chances of convection do lower as the upper high pressure ridge
builds in over the region.
Surface high pressure to the south of Arkansas has brought a south wind
flow into the region...and has kept moisture levels up. Dew point
temperatures were from the upper 60s to lower 70s state wide...while the
highest were in central to eastern areas. 00z klzk sounding had
the lowest precipitation water value around the region...and was 1.43
inches...while ksgf at 1.62 inches and kshv with 1.57 inches.
There does remain dry air through the atmosphere and did see
mixing out on Wednesday with afternoon dew point temperatures lowering
into the 60s. Consequently heat index values were lower and from
the middle 90s to less than 105. Expect the same today and will
again issued a Special Weather Statement to highlight the heat and
humidity. Otherwise...aloft the upper ridge was holding over
Arkansas...keeping any significant short wave energy well north of the
state. On Wednesday...did see a few isolated storms over far
southern...far western and to far northeastern Arkansas...but do not see
much today due to increased middle level heights. An isolated storm
can not be totally ruled out due to strong heating in the afternoon.
Short term...today through Sunday night
Mostly sunny...dry and hot today. Highs are expected to be just a
degree or two above Wednesday values. This will raise heat index
values a few degrees...but still keep levels below advisory
criteria. Will issue statement highlighting heat and humidity.
Little change in the forecast Friday and over the weekend. The
upper ridge holds over the region...centered just to the south of
Arkansas to over Arkansas...keeping short wave energy away from Arkansas...and
keeping the forecast hot and dry. The south winds will also hold
through the short term...and keep moisture levels up and dew
point temperatures in the 60s to middle 70s. The south winds will be
elevated a bit in the afternoon and give some relief in the heat.
High temperatures will nudge up to the middle and upper 90s over the weekend
with a few locations near 100 degrees...while keeping heat index
values from the upper 90s to around 105 degrees. Some areas at
some point will see heat index values over 105 degrees...and a
heat advisory may be needed over the weekend.
Long term...Monday through Wednesday
Upper ridge will be in place to start the long term...but then
guidance differs on how quickly the ridge breaks down. The GFS
breaks the ridge down quickly and allows a trough to move into the
Midwest...while the European keeps the ridge overhead.
However...both models are hinting at Gulf moisture moving
north...and have kept small rain chances in the grids.
The hot temperatures will continue in the extended...with readings
in the River Valley approaching the century mark. With Gulf moisture
moving north...heat headlines may be needed.