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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
1236 PM CDT Sat Sep 5 2015

Synopsis...
issued at 310 am CDT Sat Sep 5 2015

Aloft...upper low over Oregon and ridging spanning the central US.
At the surface....cold front extends from low in western Ontario to
low over eastern Wyoming. Second feature of note is increasingly diffuse
stationary front over northern Illinois and northeast Iowa.
Showers continue to percolate along and north of the front this
morning in northern Illinois and into southern Wisconsin.

&&

Short term...(today and tonight)
issued at 310 am CDT Sat Sep 5 2015

Showers and small area of light rain north of the stationary front
will continue to move slowly southeast along the front. Trend
should be for precipitation area to shrink and weaken as upper support
lifts out to the northeast this morning. Cannot rule out isolated
showers redeveloping this afternoon near remnants of the warm
front over northern Illinois...thus have kept low probability of precipitation for this
eventuality.

Otherwise...another hot and muggy day today with temperatures around 90 and
heat indices this afternoon in the middle to upper 90s. Some middle cloud
remnants will likely initially hold temperatures down a bit...especially
along and east of the Mississippi. However...south wind increasing
to about 10 kts after sunrise and associated warm advection should
offset the potential temperature reduction across most of the County warning forecast area.

Long term...(sunday through friday)
issued at 310 am CDT Sat Sep 5 2015

Unsettled with periods of wet weather through middle-week then turning
much cooler by next weekend.

Persistent upper ridge /heat dome/ will break down and flatten
through early next week... as a vigorous upper level trough
ejects from the intermountain west to the central Canadian prairies.
An attendant cold front will sag into the area by early in the week and
stall in or near County Warning Area until middle-week as the boundary becomes parallel
to middle level flow with the upper level wave lifting away from the region.
Anomalously high moisture aided by southwest monsoon with embedded
remnants of Tropical Storm Kevin look to push precipitable water values
in excess of 2 inches. This deep moisture coupled with the front and
perturbations embedded in southwest monsoonal fetch will result in
unsettled period of wet weather Sunday night through Tuesday night with
periods of showers and storms. Areas of heavy rainfall will be possible
given the very high precipitable water values...and wouldnt rule out some
localized flooding issues if areas see repeated rounds of precipitation.
Specific timing and favored locations for rainfall still difficult to
pin down this far out... which unfortunately leads to having likely probability of precipitation
over several days from Sunday night through Tuesday timeframe. Sunday
will be the last of the hot days with widespread lower 90s for highs
then thereafter into middle-week will see temperatures cooling down being modulated
by the clouds and rain.

Suggestions of at least temporary drying middle-week as upper trough pushes
into Ontario and attendant cold front sags south of the County Warning Area. Then
the GFS... ecm and Gem show more agreement on ejecting another trough
through the central Continental U.S. Late Thursday-Friday time period which will be
accompanied by shower chances. Stronger cold front attendant to this
system will sweep through the area by the weekend and looks to usher in
dry weather and much cooler conditions with fall-like temperatures next weekend
with 850 mb temperatures per GFS and ecm lowering to around 3c to 5c. This
would suggest potential for u30s/40s for lows by Sunday am and highs in the
60s. This in line with latest 8-14 day (sep 12-18) outlook of below normal
temperatures for the region.

&&

Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1235 PM CDT Sat Sep 5 2015

An upper level ridge will keep VFR conditions in place today
through tonight. Isolated showers and thunderstorms will continue
to occur along a weak surface boundary over northwest
Illinois...likely staying east of the dbq and mli terminals.
Lingering humidity may lead to MVFR fog overnight...which is
only included at the dbq terminal...where conditions are most
favorable.

&&

Dvn watches/warnings/advisories...
Iowa...none.
Illinois...none.
MO...none.
&&

$$

Synopsis...dmd
short term...dmd
long term...mm
aviation...sheets

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