Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Des Moines Iowa
638 am CDT Tuesday Jun 30 2015

Short term /today/...
issued at 351 am CDT Tuesday Jun 30 2015

Iowa remains in established northwest flow aloft with baroclinic
zone setting up along the Missouri River valley today. Warm
advection across the Dakotas along this tightening gradient already
producing some showers and thunderstorms overnight. A weak wave
moving along the baroclinic zone will help focus low level
convergence into western Iowa by later this afternoon along with middle
level lift which will support scattered thunderstorms activity by
later this afternoon. Have included low probability of precipitation in the far west by middle
afternoon as convection expands into the area although the best
threat for convection will be into tonight. Otherwise...clouds will
be on the increase with the approaching shortwave in addition to
some smoke from the Canadian fires drifting overhead. This should
impact temperatures with readings holding below normal into the

Long term /tonight through Monday/...
issued at 351 am CDT Tuesday Jun 30 2015

The upper Midwest will remain in a general northwest flow until well
past the extended forecast period. This will bring seasonal
temperatures and tolerable humidities to the region but we will also
be susceptible to every shortwave riding through the flow. The
first shortwave will impact the southwest half of the state tonight
into Wednesday bringing a chance for showers and thunderstorms.
While we are not looking particularly unstable...there is some
pretty impressive shear moving across southwest Iowa and as such
there will be some threat of storms being capable of large hail and
damaging wind...especially in the evening.

The models are in decent agreement with dropping another shortwave
across the southwest half of the state Thursday into Friday but
shear is almost non-existent and instability is even weaker than
today so while we may see some showers and thunderstorms with this
system the threat of severe storms is not impressive.

The parade of shortwaves will continue through the Holiday weekend
but overall precipitation chances look pretty low until late Sunday into
Monday when a frontal boundary will cross Iowa coincident with yet
another shortwave. Instability will be quite impressive as the front
moves through during peak heating and there will be sufficient shear
as well so some severe storms can be anticipated late Sunday and
Monday. Temperatures will actually be seasonably cool through
Friday with highs from the upper 70s to middle 80s. Lower to middle 80s
are expected for the most part over the weekend.


issued at 638 am CDT Tuesday Jun 30 2015

Smoke from Canadian wildfires will continue to produce a high
level haze layer across Iowa today with increasing clouds in
western Iowa. Some haze is expected early in the forecast but VFR
ceilings and visibilities will be most common later today into
tonight. Thunderstorms are expected to increase in coverage
tonight...especially in western Iowa with MVFR to IFR conditions
in and around thunderstorms. Winds will remain quite variable
across the state with a weak pressure gradient for much of the
forecast period.


Dmx watches/warnings/advisories...none.



Short term...cogil
long term...fab

National Weather Service Glossary of Abbreviations