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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
707 am CDT sun may 3 2015

issued at 700 am CDT sun may 3 2015

Based on radar trends...the forecast has been updated to account
for the convection across central/southern Iowa. This convection
is the result of the new upper level disturbance created by the
overnight storm complex in western Iowa.

As such...more clouds will be seen through the morning hours
before clearing occurs in the afternoon. Maximum temperatures have
been lowered slightly and may need to be lowered further depending
upon cloud/precipitation trends through the morning.


issued at 335 am CDT sun may 3 2015

06z objective analysis has a weak low west of kykn with a boundary
running southwest into eastern New Mexico. The main cold front ran
from northwest Minnesota into southwest South Dakota. Dew points
were in the 50s across the plains with 30s and 40s over the Great
Lakes and behind the front in the Dakotas.


Short term...(today and tonight)
issued at 335 am CDT sun may 3 2015

Rap trends and nowcasting have been used to take into account
sensible weather trends through sunrise. The large storm complex
along the Missouri River will continue to slowly move east through
sunrise as will the smaller complex in central Iowa.

Overall moisture/forcing trends support the central Iowa storm
complex to move into the western parts of the area and slowly decay
as it leaves the better moisture behind. Ahead of this complex
isolated to scattered sprinkles/very light showers along/east of the
Mississippi will continue moving east.

After sunrise...the better forcing weakens quickly which should
cause the western Iowa storm complex to dissipate. Some lingering
showers from this complex may or may not make it into the far
southwest/west areas before dissipating. The remainder of the area
will either remain dry or see some lingering sprinkles.

Cloud cover will dictate how warm it will get today. If the high
cs/cirrus clouds dissipate quickly...then the potential is there for low
to middle 80s across the area. If clouds remain for much of the day
then highs of 75 to 80 are more likely.

Mainly dry conditions should be seen through late afternoon across
the area due to the lack of forcing across the area. If temperatures
would get into the middle 80s...then the potential is there for
isolated diurnal convection.

Tonight...the main front approaches the area. Forcing/moisture is
maximized along the front so rain chances would be highest there.
However...moisture flowing north should result in isolated to
scattered convection developing ahead of the front. Internally...
some models are suggesting the possibility of another organized
thunderstorm complex developing over the area. If this would happen
to occur...then probability of precipitation would have to be raised after midnight.

Long term...(monday through saturday)
issued at 335 am CDT sun may 3 2015

Convective trends/coverage/rainfall amounts will be the main
forecast issues during the long term period.

In general...forecast still looks on track with only minor changes
necessary. A frontal boundary is expected to stall out near the
southern fringe of the forecast area Monday and slowly push north
Monday night with increasing coverage of showers and thunderstorms.
The entire forecast area is in the marginal 5 percent risk area for
Monday. The main threat will be isolated marginally severe
hail...but meager deep layer shear will preclude any significant
threat. With the stagnant surface flow and upper wind close to the
surface boundary orientation...thinking some decent rainfall amounts
are a good bet through Monday night with a low risk of flooding.

On Tuesday...there is a general consensus on the main focus of
additional rain shifting along and north of Interstate 80. Little or
no rain is expected Tuesday night into Wednesday...but Thursday
through Saturday look more active with persistent southwest flow.

The coolest temperatures will be Monday and Tuesday across the
north...otherwise 70s to low 80s and perhaps even a bit warmer are
still on target...depending on clouds and rain coverage.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 700 am CDT sun may 3 2015

Mainly VFR conditions are expected through 00z/04 with decaying
convection through 18z/03. Although small...the potential is there
for a rain showers and maybe a thunderstorms and rain to affect a taf site with a brief
period of MVFR conditions. After 00z/04 a cold front will slowly
move into eastern Iowa. New convection is expected to develop with
conditions slowly decaying to MVFR through 12z/04.


Dvn watches/warnings/advisories...


short term...08
long term...rp Kinney

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