Area Forecast Discussion
Issued by NWS Huntsville, AL

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS64 KHUN 020817

Area Forecast Discussion
National Weather Service Huntsville AL
317 AM CDT Fri Jun 2 2023


Issued at 317 AM CDT Fri Jun 2 2023

High pressure continues to hold in place over eastern Canada.
On the southern edge of this area of high pressure over the
southeastern CONUS, a very weak boundary is in place separating a
a more moist airmass near and south of it from drier air further
north. Calm winds are in place across much of the area. This may
allow some patchy fog to form near and west of the I-65 corridor
overnight, but increasing cloud cover and an approaching upper
level disturbance towards daybreak should keep it very patchy.

This disorganized and fairly weak upper level disturbance
will continue to move from east to west aloft over this boundary
tonight. This forcing has been able to produce some scattered
showers over northwestern Georgia into far northeastern Alabama
over the past few hours. This activity is moving west and should
continue to do so into the day on Friday. Some higher dewpoints
temperatures could advect into northern Alabama (mainly near/west
of the I-65 corridor) into the daybreak hours on Friday. However,
most areas will generally see lows in the lower to mid 60s.

Expect mostly shower activity until after 10 AM into the
afternoon hours, as the forcing pushes further west into
northwestern Alabama into the early/mid afternoon hours. This
activity should dissipate during the early evening hours, as we
lose daytime heating and the forcing moves southwest of the area.
Instability does climb to between 1000 J/kg and 1500 J/KG roughly
in the afternoon. However, with no shear general thunderstorms
look to be the rule of thumb.


(Tonight through Sunday night)
Issued at 317 AM CDT Fri Jun 2 2023

Even drier air will advect southward into northern Alabama tonight
into Saturday morning. This should lower precipitation chances. An
isolated shower or thunderstorm cannot be ruled out though during
the mid afternoon into the very early evening hours near southern
middle Tennessee and possible towards NW Alabama. Mainly due to
some forcing that could edge into those areas as a stronger
disturbance moves into Virginia and Northern Carolina. Again, not
expecting anything more than garden variety thunderstorms.
Saturday will be cloud free much of the day and with 925 mb
temperatures forecast to reach the 22 to 26 degree range, highs in
the 90 to 95 degree range look very possible. Luckily, drier air
will keep heat index values very close to actual temperatures.

Dewpoints will still to creep back up Saturday night into
Sunday, as the disturbance that brought showers/thunderstorms to
Virginia rotates southwestward in the upper levels and into
Tennessee and northern Alabama during the afternoon hours. Shear
will remain non-existent, but better instability/moisture
convergence does focus along and upstream of this disturbance
over the area. Some stronger storms could occur, but no severe
weather is expected at this time. Higher coverage though of
showers and thunderstorms looks like a good bet Sunday afternoon.
Given the slow movement, will have to watch for some localized
flooding given instability and PWATS.

This activity should decrease in coverage late Sunday night into
Monday morning.


(Monday through Thursday)
Issued at 317 AM CDT Fri Jun 2 2023

What could be described as a higher latitude blocking pattern should
remain in place as we get a new work week underway. This block, more
resembling an Omega-type (it`s upper high over the Northern Plains,
and respective lows over the western and eastern coasts of the
continent respectively - to a degree). Given changes in the positions
and strengths of the block`s lows, especially the eastern one will
affect what occurs more locally. Overall for the period, the
Tennessee Valley will be SE of the upper ridge and SW of the upper
low over the SE Canada/New England region.

From this morning`s model runs, the 00Z ECMWF seemed to be coming
around what the GFS has been showing the past few days regarding
development of the upper trough to our NE. Newer guidance overall has
gone back to a stronger low, and displacing it more to the south.
This will result in a wedge type front driving southward from the
Great Lakes to across the Valley on Wednesday. The boundary by the
time it reaches the area will be weaker, but noticeable enough to
cool daily highs from the upper 80s Mon/Tue into the mid 80s

Enough moisture remaining and strong solar insolation will
destabilize the atmosphere, and continue bringing mainly afternoon
shower and thunderstorm chances each day. Overall thunderstorm
strength should remain sub-severe; however the usual gusty winds,
heavy downpours, and lightning strike are always a possibility.


(06Z TAFS)
Issued at 1040 PM CDT Thu Jun 1 2023

VFR conditions are expected through the TAF period with light
winds. The only exception will be during the late afternoon when
an isolated thunderstorm may impact the terminals. However,
confidence is low so have kept as PROB30 group.




AVIATION...GH is the U.S. government's official web portal to all federal, state and local government web resources and services.