FXUS64 KMRX 231842

Area Forecast Discussion
National Weather Service Morristown TN
242 PM EDT Wed Aug 23 2017

.SHORT TERM (This Afternoon through Thursday)...

A quiet weather pattern is setting up over the short-term forecast.
The cold front is now to the east of the Appalachian Mountains with
drier air advecting in from the northwest. There were a few showers
earlier this morning across the higher elevations but not seeing
much in the way of radar returns currently. Visible satellite
indicates a field of cu across the region but nothing that looks
impressive. For now, have continued a small mention of precip. for
the higher elevations over the next couple of hours with dry
conditions forecast afterward.

PW values will take a significant drop tonight with cold and dry air
advection moving into the region. Values will range from 0.6-0.8
inches. These values are below the 10th percentile for late August.
Therefore, not expecting any precipitation overnight. There could be
some areas of patchy fog with clear skies and light winds overnight.
Low temperatures will be cooler than normal ranging from the mid
50s to mid 60s. The drier air advecting in should limit any
widespread fog issues. The atmosphere remains under the same
regime during the day on Thursday. Temperatures will warm quickly
with plenty of insolation but will top out below normal in the mid
70s to mid 80s.

.LONG TERM (Thursday night through Wednesday)...

At the beginning of this forecast period, we are on the southern
end of an upper level NW flow, while at the surface, in the wake
of the cold front, high pressure and north winds continue to build
into the area, resulting in dry weather. However, all eyes are
focused on the western Gulf of Mexico where Harvey is forecast to
be off the TexMex coasts, but in particular for the SE US, where
Harvey will be located toward the end of this forecast period and

Back to the early parts of the forecast--the dry weather looks to
continue area-wide through Friday night, then it looks like moisture
might build back along the eastern mountains to give a chance of
showers there for Saturday and Saturday night, then by Sunday enough
moisture will return to the area to have a chance of showers and
storms over the rest of the area as well. Low level moisture will
continue over the area through the remainder of the forecast with
chances of showers and storms.

There is agreement that by the end of this forecast period on
Wednesday that Harvey would still be well west of here. The longer
it takes to move east, the less impact it would have, even if it
moves directly through the area. We will need to keep up on the
latest trends for both the timing and the path of this tropical
system. Harvey will likely help continue to feed moisture northward,
even well to the east, but there will likely be some dry slots
behind areas of lift, that will be deeper in the details as well.
Right now, will continue with "chance" POPs for these periods.


Chattanooga Airport, TN 65 85 64 86 / 0 0 0 0
Knoxville McGhee Tyson Airport, TN 62 82 61 82 / 0 0 0 0
Oak Ridge, TN 61 82 60 83 / 0 0 0 0
Tri Cities Airport, TN 58 79 57 80 / 0 0 0 0




Back to Main Forecast Discussion Page