Area Forecast Discussion
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FXUS64 KMRX 180756
Area Forecast Discussion
National Weather Service Morristown TN
256 AM EST Sat Feb 18 2017
.SHORT TERM (Today and Tonight)...
Temperatures this morning are the coldest expected throughout the
forecast period. Some of the cooler valleys will start off in the
mid to upper 30s with most locations in the 40s. The main feature in
the short-term forecast will be the closed low currently located
near Texarkana. Current water vapor imagery indicates moisture
being pulled northward with this system from the Gulf of Mexico
into the Lower Mississippi and Tennessee River Valleys. An upper
level ridge exists just ahead of the advancing closed low
stretching from the Florida Peninsula northwestward into the Ohio
River Valley. At the surface, high pressure is now over the
Atlantic with southerly flow across the area in the low levels. PW
values will increase throughout the morning as moisture advects
into the area. Model soundings indicate that the atmosphere will
saturate from the top down as the upper low moves closer.
Widespread light showers are forecast today as the system moves
in. Rainfall amounts should be light with amounts ranging from
0.10-0.25 inches. Widespread cloud cover and precipitation will
keep temperatures in the 50s throughout much of the day. Due to
this, went on the lower side of guidance. The closed low will
transition into an open wave late in the short-term period over
the Mid-Atlantic. A ridge will build in quickly behind the
departing system. Northwesterly flow will keep precip. chances in
for the higher elevations early Sunday morning.
.LONG TERM (Sunday through Friday)...
A few showers may linger over far northeastern locations early
Sunday morning as Saturday`s system exits the area.
Otherwise...the extended begins in a quiet weather pattern as a
high pressure ridge builds into the eastern U.S. This will result
in dry and seasonally warm conditions for Sunday and Monday. For
the rest of the extended...model and run consistency remains quite
poor. The GFS is faster and wetter with the approach of a cold
front...progging it into the region Tuesday into Tuesday night.
The ECMWF is slower with the feature...bringing it through Tuesday
night into Wednesday and trending towards a weakening frontal
passage. For Thursday...the GFS has fairly zonal flow in place
with a weak impulse moving through then brings low pressure system
in around the Friday time frame. The ECMWF for the same period
shows weak ridging for Thursday with a system approaching but not
quite reaching into the area for Friday. With overall confidence
low...will make little in the way of changes to the current
forecast and continue with a strong chance pops for Tuesday night
and Wednesday...low pops Thursday with increased chances for
Friday. As for temperatures...will remain in a warm pattern with
above seasonal temperatures throughout.
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 61 45 70 46 / 60 10 10 0
Knoxville McGhee Tyson Airport, TN 59 46 67 44 / 40 30 10 0
Oak Ridge, TN 58 46 67 44 / 40 30 10 0
Tri Cities Airport, TN 59 44 64 42 / 50 50 10 0