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Area forecast discussion 
National Weather Service Huntsville Alabama
1231 PM CDT Wednesday may 27 2015

Update...
for 18z tafs

&&

Discussion...
/issued 1050 am CDT Wednesday may 27 2015/
a short wave currently in southern Arkansas and la is at the base of a
trough axis that extends up into the western Great Lakes. This short
wave is already keeping the remnants of an mesoscale convective system alive and as it moves
east-northeast today...it will allow additional development across the Tennessee
Valley.

Overcast/broken low clouds were over the Tennessee Valley this morning. Northwest Alabama was
able to scattered out for a portion of this morning which has allowed them
to destabilize ahead of the approaching line of
showers/thunderstorms in MS. Cloud cover is still trying to lift from
this morning along with additional middle and high clouds streaming in
from the mesoscale convective system in MS/la. With this...adjusted the cloud cover for today
by increasing it this morning. Depending on how well we are able to
scattered out clouds before this afternoon will reflect on how well we can
destabilize for this afternoons convection.

GFS and rap fcts soundings have more cape with values 1500 to 2000
j/kg where the NAM is less subtle with 500 to 1000 j/kg. With the
short wave and trough axis moving over this afternoon...the lapse
rates will steepen. This will overcome the small warm nose that is
present in the NAM bufr and 12z bmx soundings around 500mb. With
temperatures forecasted to be in the lower 80s...the cape will be around
1500 j/kg. Shear is marginal up to 30kts. Storms could have the
potential to be strong to marginally severe. Main hazards with the
strongest storms would be wind gusts up to 60mph...heavy rainfall and
small to marginally severe hail. Increased probability of precipitation across the board
today as alignment and timing of the upper level support is better
and some destabilization has already been realized this morning.

Jms

&&

Aviation...
for 18z tafs...
an upper level disturbance will move through the Tennessee Valley
today and will generate scattered showers and thunderstorms. A line
of storms has formed in western Mississippi and should enter the area
between 19-21z this afternoon. However...a few storms could develop
ahead of the line and amendments will likely be needed to account
this. Strong surface wind gusts of 30 to 40 miles per hour possible with a few
gusts up to 60 miles per hour in the stronger storms. Small hail and frequent
lightning can also be expected near any thunderstorms today.

Activity is expected to taper off after sunset as we lose peak
heating. A few showers will be possible at both terminals through
03z. Patchy fog/haze may develop again overnight with mainly MVFR
conditions expected...however...could see brief periods of IFR closer
to sunrise Thursday. Thunderstorms will be possible again Thursday
afternoon across the Tennessee Valley.

Stumpf

&&

Hun watches/warnings/advisories...
Alabama...none.
Tennessee...none.
&&

$$

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