Scientific Forecaster Discussion
fxus64 kmeg 180125
Area forecast discussion
National Weather Service Memphis Tennessee
825 PM CDT Sat Aug 17 2019
temperatures are trending downward as the sun sets over the mid-
south. Overnight lows will generally be in the lower 70s with
light winds and clear skies. Not much going on during this period.
Only minimal changes were made to the hourly forecast parameters.
Looking ahead to tomorrow, there remains some uncertainty
regarding the potential for afternoon showers and thunderstorms. A
compact shortwave trough will move into the Ohio Valley tomorrow,
aiding in convective development upstream over MO. A few of the
hi-res models are more aggressive with this system, bringing a
decaying line of storms into eastern Arkansas after 18z. However, some
guidance limits this development with generally dry weather
continuing across the mid-south. The slight chance pops along and
west of the MS river look to be in good order given this
uncertainty. Regardless, the heat will continue with highs in the
mid 90s and afternoon heat indices generally in the 98-104f range.
Previous discussion... /issued 244 PM CDT Sat Aug 17 2019/
Clear to mostly sunny skies across the region today with the
northeast counties seeing the greatest change in temperatures and
humidity from this time yesterday. This hour most heat indices
were ranging from the upper 90s...to right at 105f in Clarksdale,
Mississippi. Winds were either calm or light from a westerly
component. Current radar was showing no echoes.
For tonight and Sunday...not much change expected with the
ongoing forecast. Short term models show another complex of storms
developing overnight in the Central Plains and moving southeast
into southern Missouri by sunrise. A stray shower isn't out of the
question in the northwest counties. Most of the midsouth will
remain mostly clear with light winds tonight...with lows generally
in the 70-75f range. Highs tomorrow will top out in the low and
mid 90s...with heat indices flirting with 105f along and west of
the Mississippi River. A heat advisory may be needed. This is also
where an isolated shower or storm will be possible as slightly
stronger low level shear moves up the Delta during the afternoon
hours. Questions begin to arise for convective chances tomorrow
night. The 12z GFS run showing a complex of storms initiating
along an outflow boundary in southern Missouri and scouring out
the airmass in our region during the night. The NAM and Euro not
anywhere near as bullish...so kept only a slight chance across the
far north for now. Lows will remain in the 70-75f range Sunday.
Monday through Thursday...upper heights will slightly build
eastward over the area early in the period as a upper high center
shifts into Oklahoma. This should trigger more mid 90 degree
highs and more widespread dewpoints in the mid 70s. As a result
heat advisories are anticipated. Only caveat will be convection in
the afternoon and early evening hours which would provide heat
relief but frustrate the timing of any advisory. By Wednesday...a
stronger shortwave will begin to lower upper heights in the Great
Lakes and Midwest...prompting a descending cold front to reach
the lower Ohio Valley late in the day. The latest Euro though is
slower with this push happening Thursday. Have taken a blend of
both models...keeping temperatures a tad warmer both days and
bumping up rain chances in the Wednesday night time frame.
Beginning of next weekend...rain chances will continue...especially
along the aforementioned decaying front across the southern and
western counties where stronger shear may evolve from a weak
surface wave forming in northeast Oklahoma. Temperatures this
period will be close to seasonal averages.
/00z taf set/
VFR conditions should prevail through the next 24+ hours at all
sites. Light winds, generally from the south.