Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
1021 am CDT sun Jul 24 2016
updated to cancel heat advisory.
Shear axis/remnant mesoscale convective vortex is continuing to bring significant cloud
cover to the midsouth this morning...with likely new scattered
convection expected by early this afternoon. Have lowered high
temperatures and thus heat indices for today accordingly. Though a
County or two may top out at 105f the majority of the region will
be lower to include the Memphis Metro. Depending on how far this
feature tracks westward tomorrow...the heat may be able to build
back in across portions of the area for additional heat headlines.
Previous discussion... /issued 600 am CDT sun Jul 24 2016/
Discussion... /issued 419 am CDT sun Jul 24 2016/
Primary interrelated forecast challenges remains heat indices and
Early morning GOES water vapor imagery showed a broad upper level
height ridge across the southern half the Continental U.S.. this upper ridge
had deamplified from its position over the Central Plains several
days ago. In addition, a weak nearly stationary easterly wave and
extensive mid/upper level cloudiness was present over the lower
MS River Valley. This wave will drift slowly west into Arkansas/la by
this afternoon, likely initially focusing thunderstorm development
in this region. In the weakly-sheared environment, additional
thunderstorms will likely develop along eastward-expanding
outflow boundaries into the midsouth.
In areas not affected by thunderstorm outflow, heat indices could
quickly warm above 105f. The heat advisory has been carried over
today, but the initial presence of high clouds and low level
thunderstorm outflow later today limits forecast confidence.
Similar conditions expected for Monday. Given the limited forecast
confidence, and after collaborating with surrounding forecast
offices, have deferred extending the heat advisory into Monday.
Tuesday will see the arrival of weak westerly upper level flow
and additional destabilizing effects of a stationary sheer axis
near the arklamiss. Northwest upper level flow will gradually
increase in strength with height falls through late in the week,
leading to continued rain chances and daytime temperatures
moderating to near or slightly below normal as we close out July.
12z taf set
Isolated tsras continue to affect kmem at this time. Expect them
to dissipate by 13z. By 16-18z, expect isolated to scattered
showers and thunderstorms to develop across the mid-south. Will
continue thunderstorms in the vicinity wording at all taf sites through 01z for now. Too
hard to pinpoint best timing for convection at this time. Winds
will generally be from the south today around 6 kts. Light and
variable winds expected during the evening hours into the