Area forecast discussion
National Weather Service Des Moines Iowa
620 am CDT sun may 19 2013
Discussion...today through Saturday/...
issued at 407 am CDT sun may 19 2013
Ample weather during the forecast period with ongoing convection
passing through the forecast area. This arc of thunderstorms is
expected to progress northeast out of the area toward 12z. There
may be some lingering convection...however it appears there will
be some down time during the day with weak subsidence on the
backside of this convection this morning. This should allow daytime
heating to progress with instability increasing throughout the
day. Will also see shear begin to increase as middle level speed maximum
approaches late in the day. Potential for severe weather looks
good by late afternoon into the evening with best parameters
across the south. All modes of severe weather will be possible
including large hail...damaging winds with a few tornadoes also
possible...especially in the south and west.
The convection will pull northeast across central Iowa tonight as
shortwave moves quickly through the state. Will likely see
convection diminish over the forecast area late tonight as drier
air aloft moves across the state. Exception would be in the far
north where forcing lingers and convection may persist for much of
the night. Will continue to monitor this area for potential heavy
rainfall and the possibility of flash flooding given the previous
heavy rains of earlier in the week.
Upper low will sit and spin for the early part of the week
bringing chances of convection on Monday into Tuesday with
additional threat of severe weather...mainly east during this
time as moisture and shear remain in place. Upper system will
eventually pull away later in the week with drier weather into
Thursday and Friday. However...the break appears short lived as
warm advection and moisture transport increase late Friday into
Saturday. This will bring additional chances for thunderstorms
late in the period.
&&
Aviation...19/12z
issued at 614 am CDT sun may 19 2013
Majority of thunder out of the area with a small area moving into
south central Iowa at this time. Models having tough time with placement of
thunder chances today...and therefore have been more pessimistic
earlier today regarding thunder chances and stuck to best timing
for thunder which will be late this afternoon into this evening
at all taf sites. High-res models suggesting area of
showers/thunderstorms over east central Kansas to lift northward
with additional development from about kdsm eastward by late
morning into the afternoon. Somewhat skeptical on this scenario so
kept the terminals dry for now. Southeasterly to southerly winds
expected throughout the period. Again...widespread thunderstorm
activity expected by late afternoon into the evening hours.
&&
Dmx watches/warnings/advisories...none.
&&
$$
Discussion...cogil
aviation...beerends
