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

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FXUS64 KMRX 111903

National Weather Service Morristown TN
303 PM EDT Tue May 11 2021

.SHORT TERM...(Tonight and Wednesday)...

-Some mainly light rain moving in for later tonight/early Wednesday

-Drier by Wednesday afternoon but still cool

We will remain in nearly zonal flow aloft for the short term period,
while at the surface a stationary front is located to our south
across the Gulf coast states and surface high pressure is centered
to our northwest. Some weak short wave energy will move by to our
south later tonight/early Wednesday. Models still disagree on how
significant and where forcing from the jet to our northeast will
occur, with the NAM showing much better forcing as the right
entrance region of the jet moves by.  As a result, the NAM has more
of a surface wave on the frontal boundary to our south and has much
more significant precipitation over our area. This wetter solution
looks to have little support from other models, so plan to lean
toward the blended NBM solution for PoPs which shows likely south
ranging to slight chance northwest later tonight into early
Wednesday.  Precip amounts should be on the light side most areas.

The precipitation will exit from northwest to southeast and drier
air will be working in during the day Wednesday.  However,
high temperatures will be well below normal for this time of year.


.LONG TERM...(Wednesday Night through Tuesday)...

Key Messages:

1. Light rain chances will be present Thursday and Friday

2. Temperatures will steadily warm up through the weekend.

3. Better chances for showers and thunderstorms early next week.


Wednesday night into Thursday the zonal flow will continue with
little changes in the weather expected. By Thursday
afternoon/evening a weak shortwave will dive out of the northern
stream towards the Tennessee Valley. Precipitation chances with this
system will remain relatively low as there is not much energy
associated with it, the mid to low levels of the atmosphere remain
fairly dry, and surface ridging will also inhibit rain chances. Will
continue with low end precipitation chances on Thursday, with
chances lingering into Friday in southwest VA and northeast TN as
they`re closer to the shortwave as it moves out of the area.

Ridging begins to build in at the mid levels and near the surface
which will lead to mostly sunny skies and a warming trend for the
end of the week through the weekend. Temperatures are expected to
get back to seasonal normals by Sunday or Monday.

Chances for showers and thunderstorms begin to increase early next
week as low level winds turn more southerly and bring in more Gulf
moisture. At the same time models try to drag a front through the
Ohio/Tennesse Valley`s early next week and bring widespread showers
and thunderstorms to the eastern half of the U.S. Models are in
fairly good agreement that there will be a strong system in the area
early next week, but are still off in timing and location of the
front and other synoptic features with this system. Will continue to
stick close to guidance early next week, but confidence is not very
high at this time due to wide model solutions with how to handle
this system.




Clouds will increase, and some mainly light rain showers will move
into the area later tonight into Wednesday morning. Best chance
for significant rain looks to be at CHA, so will include rain
showers along with conditions lowering to MVFR levels as lower
cigs and possible vsby restrictions with fog/precip look more
likely there. Will only include vcsh at TYS/TRI along with prob30
groups that include showers and MVFR conditions late tonight into
Wednesday. Winds will generally be from the north and northeast
at less than 10kts, but winds will become a bit stronger at CHA.


Chattanooga Airport, TN             52  60  49  68  48 /  60  40  20  20  10
Knoxville McGhee Tyson Airport, TN  49  60  46  66  47 /  50  40  10  30  20
Oak Ridge, TN                       48  63  45  67  46 /  50  30  10  20  20
Tri Cities Airport, TN              45  62  41  66  45 /  30  30  10  20  30



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