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fxus63 kdmx 191045 

Area forecast discussion
National Weather Service Des Moines Iowa
545 am CDT Fri Jul 19 2019

Discussion.../today through Thursday/
issued at 356 am CDT Fri Jul 19 2019

Heat and humidity will continue to be the main concern over the
next 24 to 36 hours. Thereafter, convection chances will come
into focus later Saturday into Sunday morning. Currently, surface
front resides just north of the state with a sultry airmass in
place across Iowa. Dewpoints have only recently backed off from 80
degrees and lowered into the mid 70s in most locations. However,
with a full day of sunshine and corn beginning to tassel,
evapotranspiration will be adding moisture into the near surface
layer. This will push dewpoints back toward 80 this afternoon,
especially in the north closer to the surface boundary.
Temperatures are also likely to be a few degrees warmer given the
warm overnight temperatures and little cloud cover. Heat index
values for much of the area are likely to be from 108 to 115
degrees by mid afternoon into the early evening and have expanded
to include the entire area in the warning.

By tonight, convection near the surface boundary will primarily
by just north of the state. However, additional convection in the
Dakotas is expected to move east late tonight and may clip the
far north during the early morning hours. By Saturday, the
boundary will settle gradually southward during the day. This is
forecast to bring relief to northern Iowa with cooler temperatures
and lower dewpoints along with the threat of storms through much
of the day. Central and southern Iowa will remain in the sticky
airmass for much of the day. Instability will be quite high by
late afternoon and some convection is expected near or north of
the boundary by late in the day. However, more significant
convection is expected by the evening into the overnight as the
low level jet intensifies into the boundary. A few severe storms
will be possible with damaging wind the main concern. Very high
precipitable waters and deep warm layers will also be conducive to locally heavy
rainfall late Saturday into Saturday night.

The front will push through the state by early Sunday morning with
much cooler and less moist air pushing across the state. This will
bring and end to the threat of precipitation by midday Sunday
along with temperatures at or below normal. This break in the heat
is expected to persist for much of next week as flow aloft is much
more northerly with reinforcing shots of cooler air from Canada.


Aviation.../for the 12z tafs through 12z Saturday morning/
issued at 545 am CDT Fri Jul 19 2019

Widespread VFR conditions are expected for the duration of the
forecast. Only concern would be possible convection near the
Minnesota border this evening into the overnight. Surface winds
will remain south to southwest with gusty conditions this


Dmx watches/warnings/advisories...
excessive heat warning until 7 PM CDT Saturday for iaz023>028-

Excessive heat warning until 10 PM CDT this evening for


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