Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Birmingham Alabama
641 am CDT Tuesday Apr 21 2015
for 12z aviation.
The active and unsettled pattern took a minor reprieve
monday's as showers and thunderstorms exited east and northeast.
It seems like every system has underperformed...in the rain
amounts and coverage department...over the past few weeks. We
could have actually received more rain and thunderstorms. 3 rounds
of severe potential on sundays produced a few weak
tornadoes...large hail...and damaging winds...but overall
reports/effects were isolated...besides the beneficial rainfall.
A rather weak cold front moves into central Alabama middle week as
the Pacific originating zonal jet is slightly influenced by the
northern stream. The next and potentially more influential upper
system affects central Alabama Friday/Saturday...potentially
being the key word at this point.
High temperatures will ride near to below normal through the period
in the 70s/80s. Lows will be near normal in the 50s/60s after this
The latest water vapor imagery matches up nicely withe current
laps data and upper air plots. The mean trough axis has shifted
east of central Alabama with benign weather through much of
A weak front approaches central Alabama from the north late
Wednesday. This fornt slowly moves southward into Thursday. There
is some upward motion as a subtle upper disturbance moves through
the flow. But overall mean moisture is somewhat limited and low
level convergence is not outstanding. Will keep probability of precipitation in the
chance range for now.
Models have been in consistent disagreement with the upper
pattern Friday/Saturday and then miraculously regain some
composure into next week. A nice low level jet forms and southerly
flow usher in plenty of moisture that likely rain chances stay in
the forecast Friday night. The European model (ecmwf) would hint at some potential
for stronger storms this period while the GFS is not quite as
robust. With this scenario Goin on for days...will keep the
ongoing forecast fairly close with only minor changes. Will also
not add anything to the severe weather potential statement at this time...but monitoring these
developments will be prudent. Do remember we are in The Heart of
Spring severe weathr season.
The unsettled reprive does not long as one system affects US
by middle week and yet anoher system on Saturday. Withthe evolution
aloft so iffy...will not add specifics for central Alabama at thsi
12z taf discussion.
VFR conditions expected the next 24 hours. Models hint at some
middle-level cloudiness tonight...but nothing of operational impact.