Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Huntsville Alabama
1227 PM CDT Sat Apr 25 2015
for 18z tafs
/issued 1122 am CDT Sat Apr 25 2015/
radar is currently clear over the Tennessee Valley after a round of showers
and thunderstorms early this morning. Surface observation show temperatures around 70
degrees and southwesterly winds that may be breezy at times today.
The short wave in Kansas/MO will lift NE as the stacked surface low will move
southeast through out today. The warm front has already lifted north of the
area this morning...leaving US in the warm sector today. Could see
wind gusts and a few isolated showers/thunderstorms with the small
boundary that is currently on radar moving across northwest Alabama. To get
severe thunderstorms this afternoon we first need to erode the cap
that is in place. Also...the storms moving along the Gulf Coast will
help reduce the available deep layer moisture moving into the area.
Cape values could get up to 3000 j/kg and 0-6km shear ~60kts so
thunderstorms could turn severe quickly...but shear is
unidirectional. Will need additional boundaries to provide the lift
needed to initiate convection this afternoon. Large hail and
damaging winds are possible with any severe storm that
develops...tornado threat is low.
As for the grids...lowered the probability of precipitation for this morning since there is
no lingering rain and the cap is holding but did not taking them out
due to the small boundary moving through the County Warning Area currently. Adjusted
wind gusts for today due to current trends and for the potential to
mix down a little bit of wind this afternoon. Slightly increased
cloud cover for early this afternoon to adjust the timing of the
for 18z tafs...
Low ceilings continue to vary between scattered and broken this
morning. This trend is expected to continue through the early
afternoon...when ceilings will likely be reduced to MVFR. There is a
change for isolated thunderstorms this afternoon as well...however
confidence is low concerning where thunderstorms develop.
Therefore...will continue the thunderstorms in the vicinity in the tafs. For any thunderstorms
that do develop...very heavy rainfall will be likely...along with
gusty winds. Southwesterly winds will also be gusty outside of
thunderstorm areas. The chance for thunderstorms diminishes by
sunset...with the loss of daytime heating. Winds will also slacken
overnight...before becoming northerly with the passage of a cold
front Sunday morning.
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