Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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FXUS64 KMRX 260815

Area Forecast Discussion
National Weather Service Morristown TN
415 AM EDT TUE JUL 26 2016

Weakening frontal boundary along the Ohio River this morning is
becoming nearly stationary. This boundary is expected to be the
focusing mechanisms for convection to its south later this
afternoon. In the middle levels, a weak 500 mb shortwave trough
will further aid in initiating convection as it shifts eastward in
the zonal flow aloft late this afternoon. With MLCAPE values of
1500-2000 J/Kg, SFC- 6km shear of 15-20 kt, and PW values reaching
to near 2 inches N of the I-40 corridor, any convection that
develops will have the potential to produce gusty damaging winds
and localized flooding. Although strongest storms will remain over
northern half of the CWA, still expect diurnal heating to trigger
afternoon and evening convection over southern areas. Although lack
of shear should limit severe potential, threat still exists for
localized flooding in a moisture laden environment. All activity
should gradually weaken with loss of daytime heating before finally
dissipating in the overnight hours.

Although temperatures will still be about 4-5 degrees above
climatological averages, expect that increasing cloudiness with
the approaching boundary to keep afternoon high temperatures a few
degrees cooler than we have seen in the last several days.

High pressure ridge over the Southeast the last several days is
expected to shift east into the Atlantic by Wednesday. A weak
stationary front over the Ohio Valley and mid Atlantic will move
little on Wednesday. Rainfall will be concentrated just to the north
of the region across Virginia...West Virginia and eastern Kentucky
along and north of the boundary the during the day and then increase
late in the afternoon across the forecast area. A weak upper level
low over MS will also focus more widespread precipitation to the
southwest of the eastern Tennessee Valley Wednesday then shift it
northeast overnight Wednesday night as a weak surface low moves
northeast. Rain chances will stay higher Wednesday night and
continue Thursday. Rainfall will be focused near the surface low and
along the edge of the ridge. A broad upper trough which moves into
the Great Lakes and Ohio Valley including the northern Tennessee
Valley early Thursday will remain over the region through at least
Sunday. Shortwaves moving across the forecast area will keep rain
chances higher with more cloud cover and lower high temperatures a
few degrees. The warmest day will likely be Wednesday. Rainfall
amounts may reach around an inch around Chattanooga to as much as 3
inches northern Plateau for the 5 day period ending late Saturday.


Chattanooga Airport, TN             96  76  94  75 /  40  30  40  40
Knoxville McGhee Tyson Airport, TN  94  74  93  74 /  40  30  30  30
Oak Ridge, TN                       93  73  93  74 /  40  30  30  30
Tri Cities Airport, TN              93  70  92  70 /  50  40  40  40



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