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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
1130 PM CDT Tuesday Jul 7 2015

Update...
issued at 1130 PM CDT Tuesday Jul 7 2015

Have updated the grids to mention chance probability of precipitation in our far southern
County Warning Area for late tonight as an area of rain gradually lifts northward
out of eastern MO. Precipitable waters will increase as well
allowing for the increasing rain chances. Elsewhere a dry northeast
wind has finally scoured out the haze and visibilities late this
evening were in the 7 to 10 mile range.

11 PM temperatures ranged from the middle 50s far north to the middle
60s south. I will continue to forecast minimum temperatures around
50 far north to the upper 50s far south. This will be several
degrees warmer than the record lows for July 8.

&&

Synopsis...
issued at 233 PM CDT Tuesday Jul 7 2015

12z upper air analysis has an 850mb cold front Northern Lake Huron into
southern Kansas with an 850mb high over the northern plains. A low level jet
continued to push very warm and moist air ahead of the upper front.
Satellite trends through middle afternoon show the low clouds
associated with the cold front moving south of the area with diurnal
clouds from Minnesota/WI into eastern Iowa/northern Illinois.

18z surface data has the main cold front from near kdet to near kokc.
Dew points ahead of the front were in the upper 60s and 70s. Behind
the front dew points were in the 50s to lower 60s with 40s across
the northern plains and upper Midwest.

&&

Short term...(this evening through wednesday)
issued at 233 PM CDT Tuesday Jul 7 2015

Quiet and dry conditions will be seen across the area tonight as
high pressure moves through the Great Lakes. Data from the models
points to another thunderstorm complex developing in northeast
Oklahoma/southeast Kansas and moving northeast overnight. The
leading edge of the thunderstorm complex should be just south of the
area shortly after sunrise Wednesday.

On Wednesday the convective complex will slowly move east northeast
during the day. Showers will slowly overspread areas south of I-80
during the morning with thunderstorms possible south of an kotm to
kgbg line. During the afternoon...showers should overspread all but
the northwest quarter of the area. If the dry air is deeper than
suggested by the models and/or the dry easterly flow is stronger...
then the possibility does exist that the rain may struggle to get
much north of Highway 30.

The area was hit by very heavy rain late Monday afternoon and into
Monday evening. Thus soils are saturated and any additional rainfall
would run off quickly and create problems.

Internally...the models are indicating that the stronger convection
and thus heavier rainfall should remain to the south and east of the
area. However...moderate rainfall is possible as far north as the
MO/Iowa line south of kotm northeast to kgbg. Rainfall amounts in this
area may average around one half inch.

If rainfall is under an inch for this event and falls over several
hours...the ground should be able to handle this amount based on
current flash flood guidance. However...if the complex would track
further to the north then the far south could possibly be at risk
for locally heavy rainfall. Later shifts will need to watch this
carefully.

Long term...(wednesday night through tuesday)
issued at 233 PM CDT Tuesday Jul 7 2015

Favorable regime for periods of heavy rains into early next week.

Long term forecast confidence assessment...fair or average with
poor confidence on timing of convective complexes and impacts on
temperatures...mostly high temperatures into early next week.

Overview...initialization and verification supports a 80/20 blend of
more consistent hi-res European model (ecmwf)/Gem-NH mix and then GFS. The GFS builds
upper ridge and low levels too warm and dry Friday into early next
week. Bl moisture issues suggests training of storms that is not directly
handled with complexes that will need close evaluation next few days.

Wednesday night...raised probability of precipitation southeast 1/2 to 2/3 with light to moderate
rain amounts from passing disturbance. Later shifts may need to raise
a bit more as forcing suggests rain with embedded vorticity lobe to pass
over far south east sections. Some local tools suggest rain amounts
near 1 inch or more to be considered south of Highway 34. Lows ranging
from near 55 far northwest sections to around 60 degrees southeast sections.

Thursday...fair to mostly fair with light winds and moderate humidity
from weak high pressure. Highs should be in the middle to upper 70s or
5 to 8 degrees below normal.

Thursday night through Tuesday...area conceptually in the Summer ring
of fire pattern with mostly nocturnal convective complexes lasting into
the morning hours. Local heavy rain tools support 2 to possibly 5 plus
inches could fall. This could cause additional water issues which will
be better ascertained the next day or so. Based on past event...area
highs may be 5 plus degrees or more too high for later shifts to monitor.
Isolated severe storms with strong winds and secondary concern. Overall
temperatures temperatures near to slightly below normal.

&&

Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1130 PM CDT Tuesday Jul 7 2015

VFR ceilings at all taf sites tonight into Wednesday morning. Showers
with occasional MVFR ceilings/visible will spread gradually northward out of MO
and into southeast Iowa Wednesday...spreading to kbrl in the
morning and kmli in the afternoon. Kcid/kdbq should remain dry.
Northeast to east winds through Wednesday morning less than 10
knots...then becoming southeast in the afternoon.

&&

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

$$

Update...haase
synopsis...08
short term...08
long term...Nichols
aviation...haase

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