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Area forecast discussion...corrected aviation discussion 
National Weather Service quadrant cities Iowa Illinois
1138 PM CDT Thursday Jul 31 2014

issued at 1137 PM CDT Thursday Jul 31 2014

A shortwave around 700 mb in the cyclonic northwest flow currently
moving through SW Iowa may trigger additional isolated showers over
southeast Iowa...NE MO into west central Illinois later tonight and will
keep slight chance wording going. While the potential for
thunderstorms is not zero...marginal middle level lapse rates will
support primarily weak showers and will leave thunderstorms out for
now. Otherwise...the rest of the night looks partly cloudy...which
along with slightly higher dewpoints...point toward slightly warmer
mins than last night and current forecast lows appear to be on track.


issued at 303 PM CDT Thursday Jul 31 2014

12z upper air analysis has an 850mb low near James Bay and another along
the Red River south of koun. Several very weak troughs ran from the
Middle Atlantic States back into the northern plains. Satellite trends
through middle afternoon show diurnal clouds across the area with some
convection across northeast Wisconsin and far western Iowa.

18z surface analysis has a weak low northeast of konl. Several weak
troughs ran from the eastern Great Lakes into the upper Midwest. Dew
points were mainly in the 50s across the Midwest with 60s from the
Southern Plains into the Ohio Valley.


Short term...(this evening through friday)
issued at 303 PM CDT Thursday Jul 31 2014

Satellite trends show some vertical development in the clouds across
northern Illinois and west of kcid/kiow. However...the vertical
development is very weak for peak heating. Rap trends continue to
show the inversion present above 700mb which is playing into the
lack of convection across the area.

The possibility does exist for some very isolated convection to
occur through sunset with the far east and west sections being
slightly more favored.

After sunset...another weak disturbance will rotate through the
area. Initially downward motion is occurring across the area but
some very weak lift develops by late evening and continues
overnight. Thus some isolated showers may be possible through

If development occurs with the disturbance overnight...lingering
showers will be seen across the area Friday morning. However...any
showers would be very isolated in nature.

Daytime heating and the approach of another disturbance aloft should
fire off new diurnal clouds by middle day. This disturbance is a bit
stronger than previous ones so the potential for afternoon
convection is expected to be somewhat higher. As such...convection
should be isolated to scattered across the area during the afternoon

Long term...(friday night through thursday)
issued at 303 PM CDT Thursday Jul 31 2014

Main forecast focus is on changing large scale pattern next week.

Friday night through Saturday...long wave trough over the eastern
Continental U.S....with resultant northwest flow over the upper Midwest
dominates the start of the weekend. Main short wave drops across Iowa
and Minnesota Friday night...bringing a reinforcing cold surge into the
upper trough. Thus scattered convection remains a possibility from
Friday evening through Saturday. Without a strong surface
boundary... best chances will occur in the afternoon and early
evening with peak heating. Given the cold pool aloft...could see
some pulse type storms with small hail...especially Friday evening.
Saturday is similar...although some models suggest significant
subsidence by afternoon that could suppress and convection. Thus
have highest probability of precipitation Friday evening...then lower probability of precipitation Saturday

Sunday...main storm track remains north of our area over Minnesota
and WI. This...coupled with weak ridging at the surface suggests
quiet weather Sunday.

Monday through Thursday...the ridge over the southwestern US will slowly
flatten through this period...setting up weak...gradually more
zonal flow over the area. At the surface...boundaries will be in
the region. Depending on where those boundaries set up...will have
several opportunities for mesoscale convective system/widespread rainfall to impact our
County warning forecast area...especially Wednesday into Thursday when the Gulf is prognosticated
to be more open.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1137 PM CDT Thursday Jul 31 2014

Weak showers...mostly sprinkles...may be in the brl vicinity
around midnight. Otherwise...the rest of tonight and Friday will
have mainly VFR conditions and very light winds under a broad
area of high pressure at the surface. Low level moisture may
again lead to morning ground fog...which has been included with
potential MVFR visibilities at both Cid and brl. At brl...reported
visibility may be affected at times by gravel Road dust in the
morning...much as it was Thursday evening. Skies will again be
hazy aloft at all terminals through Friday due to an extensive
plume of thick high altitude smoke streaming south out of wildfires
in northern Canada. There will be a chance for afternoon showers and
thunderstorms...but these look to few to mention in the tafs in this


Dvn watches/warnings/advisories...


short term...08
long term...dmd

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