Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Des Moines Iowa
1148 PM CDT Monday Aug 3 2015

..updated for 04/06z aviation forecast discussion...

Short term /tonight/...
issued at 321 PM CDT Monday Aug 3 2015

A surface high pressure area will slide across Iowa tonight
providing more cool and quiet weather along with light winds. The
frontal boundary that moved across the state late Monday is stalled
out across central and northern Missouri and will retreat slowly
northward later tonight...possibly producing a few showers and
storms in our far southern counties after midnight. Have maintained
low probability of precipitation in this area...but it remains to be seen whether they will
remain south of the border until tomorrow morning.

Long term /Tuesday through Monday/...
issued at 321 PM CDT Monday Aug 3 2015

Extended will see active weather pattern with multiple rounds of
thunderstorm chances expected. not have very high
confidence on timing and placement of best precipitation chances
through the period. Therefore...have generally kept forecast near
going...with widespread precipitation chances through
extended...though do not anticipate prolonged periods of
precipitation...with multiple breaks in
precipitation...especially across the central portions of the
County Warning Area.

Boundary which has lingered in southeast Nebraska and northern Missouri
will begin to slowly push back north into Iowa...bringing
thunderstorm chances. Models are a bit slower than previous
runs...though GFS is quite a bit faster and have trended away from
it for beginning of extended. Have kept best chances confined to
the southwest with high pressure retreating across the rest of the
area. Instability is best confined to this area as well...and may
see strong to severe thunderstorms in the afternoon as system
pushes in.

Boundary will linger through Wednesday...finally pushing
east...however trough will push east Wednesday and will bring
chances to the well as surface low pushing east across
Missouri bringing precipitation chances to the south. May see
precipitation chances split across Iowa...though models are not in
good agreement with timing or placement of these systems...and
have kept only chance probability of precipitation in the north and south Wednesday night
at this time. System in the south could bring heavy rain...though may be
further south into Missouri. Southern system will be quick
moving...with northern system pushing south into Iowa late
Thursday...which may be best chance for widespread precipitation
across the area. Late in week upper level low pressure system
pushes east into Canada...beginning to break down plains ridge.
With persistent northwesterly flow aloft will see continued
chances for precipitation at time through the end of period.

Continue to have low confidence in temperatures...especially highs as
precipitation trends will influence temperatures. However...given
cool temperatures aloft...have continued with trends for generally
below normal through the end of the extended.


issued at 1148 PM CDT Monday Aug 3 2015

Mainly VFR conditions are expected through the taf period with light
and variable winds. There may be some borderline VFR-MVFR fog at the
kmcw and kotm terminals overnight but have not reduced visibilities there
due to lack of confidence. Some rain showers/thunderstorms and rain may approach from
southwestern Iowa on Tuesday afternoon...but confidence not high
enough to include mention in the tafs at this time.


Dmx watches/warnings/advisories...none.



Short term...Lee
long term...awb

National Weather Service Glossary of Abbreviations