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

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FXUS64 KMRX 290531

Area Forecast Discussion
National Weather Service Morristown TN
131 AM EDT Mon May 29 2023

...New AVIATION...

Issued at 1010 PM EDT Sun May 28 2023

No major updates to the forecast this evening as everything is on
mostly on track. Only minor changes to hourly temps and dewpoints
to match up with latest obs. Biggest change was to lower overnight
lows across portions of southwest VA by a few degrees based on
current obs.


(This evening through Monday)
Issued at 242 PM EDT Sun May 28 2023

Key Messages:

1. Showers decreasing in coverage tonight with low clouds and fog,
especially across northeast Tennessee and southwest Virginia.

2. Decreasing rain chances on Monday with drier conditions and
more breaks in the clouds across most of the area as the closed
upper low moves east.


The closed upper low observed on WV imagery this afternoon across
north Georgia is forecast to move east-northeast tonight as it
begins to be influenced further by the westerlies. Upper-level
flow becomes more northerly across the region with increasing mid
to upper level subsidence and lower rain chances. With the
saturated boundary layer across most of northeast Tennessee and
southwest Virginia, expect low clouds and some fog late tonight
into Monday morning.

Light rain is expected across far northeast Tennessee and
southwest Virginia on Monday, but PoPs will be substantially less
than today. It will be mainly in the form of some light lingering
showers with the support for more widespread synoptic ascent
shifting east of our forecast area. Overall precip values on
Monday will be a tenth of an inch or less, mainly across the
higher elevations of southwest Virginia and northeast Tennessee.
With northerly flow and increasing heights, clouds are expected to
become more sct to bkn during the day with increased sunshine in
the afternoon. Temperatures will remain about 5 to 10 degrees below
normal, but will rebound from Sunday`s low max temperatures as
the closed upper low moves east of the mountains towards the North
Carolina coast.


(Monday night through next Sunday)
Issued at 242 PM EDT Sun May 28 2023

Key Messages:

1. Daily showers and thunderstorms will increase in coverage through
Thursday and decrease towards the end of the weekend.

2. Initially near normal temperatures will rise far into the 80s to
near 90 by the weekend.

Monday Night through Thursday

At the start of the period, a closed low will be over far eastern
portions of the Carolinas and weakening due to an upper ridge to the
north. As the feature continues to weaken and shift eastward on
Tuesday, PoPs will definitely be more focused on far eastern
portions of the area, closer to the feature and higher terrain.
Heading into Wednesday, heating in the lower levels will allow for
increased lapse rates and overall instability. This will allow for
better coverage of diurnal convection. On Thursday, a closed low is
indicated to develop over the northern Gulf with the better moisture
expected to stay south of the region. As such, the result will be
similar diurnal convection, especially over the higher terrain.

Friday through Sunday

Overall, a similar weak flow pattern will remain in place over the
area, meaning diurnal PoPs each day.  Model guidance all show a
decrease in moisture by the end of the period, meaning PoPs will
decrease by Sunday. With the pattern through the period being that
of the typical summertime pattern, low probability HWO wording will
be kept as very isolated heavy rainfall and/or stronger storms are
all possible.


(06Z TAFS)
Issued at 125 AM EDT Mon May 29 2023

Worst flight conditions will be north and early in the period,
with TRI expected to be MVFR/IFR with low clouds/fog and possibly
some showers around, while TYS and CHA are expected to trend to
MVFR. All sites are expected to see improvement to VFR from south
to north during the day, first at CHA and finally at TRI by late
in the period.


Chattanooga Airport, TN             78  60  84  64 /  10   0  30  10
Knoxville McGhee Tyson Airport, TN  74  56  82  62 /  10  10  30  10
Oak Ridge, TN                       75  57  83  61 /  10  10  30  10
Tri Cities Airport, TN              67  55  79  56 /  50  20  30  20




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