Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
618 am CDT Tuesday Oct 21 2014
Updated for 12z aviation discussion.
Previous discussion... /issued 318 am CDT Tuesday Oct 21 2014/
The upper level trough that moved through the region on Monday has
pushed well east of the region. Building high pressure has allowed
temperatures to cool under calm winds. Lingering boundary layer
moisture under the cool dome is promoting patchy fog
development...especially near river valleys and areas of eastern
Arkansas. Conditions will support fog through 15z this morning and
have therefore left this condition in the forecast through that time.
A relatively amplified upper level flow regime will dominate
through the weekend with longwave ridging developing across the
central Continental U.S.. the surface pattern is slow to evolve with surface
high pressure entrenching itself across the middle south through
Friday. For this reason...Max/min temperatures will remain cool
through this period with the coldest night likely occurring
Wednesday night where portions of middle Tennessee will reach the
upper 30s. A gradual warmup is expected through the weekend as
high pressure is shunted east and weak southerly/southeasterly
return flow sets up ahead of developing Lee side troughing. As the
western Continental U.S. Trough migrates eastward...warmer 850mb temperatures
advect over the middle south which should allow high temperatures to
reach the low 80s by Sunday and Monday...which will be the warmest
of the period.
In the extended periods...a return to seasonal temperatures are
expected with limited chances of precipitation. There will likely
be a frontal passage at some point with the passage of the
longwave trough axis...however...timing/location of this feature
is extremely uncertain at this time.
12z taf cycle
VFR...with light north to northeast winds through the period.