Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Morristown Tennessee
306 PM EDT Monday Aug 3 2015
Short term (tonight and tuesday)...will be transitioning into an
unsettle weather pattern through the short term as an upper trough
and weakening boundary drops south into the southern appalachian
region. An increase in low level moisture along with a couple of
weak waves moving along the boundary will allow isolated convection
to develop and move through the area. Coverage should be limited
for 20 to 30 probability of precipitation with better coverage over northern locations.
Warming temperatures will accompany the boundary with highs on
Tuesday expected to push into the upper 80s and 90s across the Tennessee
Long term (tuesday night through monday)...a nearly zonal flow
aloft very early will transition to northwest flow...as the upper ridge
builds across the plains states and rockies with troughing over the
eastern states. Likely the most significant weather factor will be
the east-west frontal boundary affecting the region Wednesday and
Thursday. Models generally agree on a more amplified shortwave
trough tracking across by Thursday night...which should push the
frontal boundary south of the southern Appalachians by late Friday
or early Saturday.
However...this frontal passage does not allow the dropping of rain
chances for the weekend...due to a hint of more weak impulses in the
northwest flow aloft plus daytime heating and any weak moisture convergence
in the higher terrain. Ensembles show rising 500 mb heights headed
our way by Sunday night and Monday...so I stayed on the very low end
of probability of precipitation for now...a bit below the superblend probability of precipitation.
For temperatures...followed the GFS MOS early...a MOS blend in the middle...
then the superblend offerings late.
Preliminary point temps/pops...
Chattanooga Airport, Tennessee 69 95 73 93 / 10 10 10 20
Knoxville McGhee Tyson Airport, Tennessee 67 92 70 90 / 10 20 10 20
Oak Ridge, Tennessee 67 91 68 89 / 10 20 10 20
Tri Cities Airport, Tennessee 65 89 65 88 / 20 30 20 30