FXUS63 KDMX 291139

Area Forecast Discussion
National Weather Service Des Moines IA
639 AM CDT Thu Jun 29 2017

.SHORT TERM.../Today through Tonight/
Issued at 412 AM CDT Thu Jun 29 2017

Convection has remained anchored near the Iowa/Missouri border
overnight on nose of strong LLJ. Additional convection has also
developed across far southern Nebraska into Kansas with a nearly
continuous line of storms from western Kansas to Illinois. There
are concerns to the extent this ongoing convection will influence
the subsequent storms that are expected later this afternoon.
Should this expansive area persist to the south of Iowa through
the morning, then airmass recovery will not be as strong as was
earlier forecast. Therefore, the evolution of these storms will be
closely monitored over the next several hours to see the impacts
on the forecast for today.

It is still anticipated for some recovery across the forecast area
today with southerly winds increasing into midday. Shorter term
models spread some convection across the west later this morning
with more rigorous convection developing by this afternoon with
the influence of the approaching shortwave increasing lift across
the state. Far southern Iowa should see best instability where
airmass recovery is expected to be better. Shear parameters remain
quite impressive for late June with bulk shear of 50kts+
spreading across Iowa this afternoon. Best low level shear remains
in southern Iowa as well and this appears to be the most likely
area of tornadoes. Some concerns for flash flooding from
additional heavy rainfall also seem valid and are discussed below.
Any convection that develops will push eastward this evening.
However, some additional scattered showers and storms are forecast
to push into the state overnight ahead of the main shortwave

.LONG TERM.../Friday through Wednesday/
Issued at 412 AM CDT Thu Jun 29 2017

Northwest flow aloft is expected behind the departing system into
the weekend and early next week. The main concern in this time
period will be from later Sunday into Monday with a front settling
into the state and and upper low approaching from the west. GFS
remains most bullish and a bit farther north the the Euro
counterpart, however both have been showing this low for several
runs. Therefore, have continued the threat of precipitation during
this time. After the departure of this system, heights begin to
build into the middle of the week with much warmer weather
becoming likely just after the 4th of July.


.AVIATION.../For the 12Z TAFS through 12Z Friday morning/
Issued at 638 AM CDT Thu Jun 29 2017

Narrow areas of MVFR to IFR conditions this morning near a weak
boundary across northern Iowa. However, most locations are VFR
this morning and will remain VFR into the afternoon. Showers and
thunderstorms are expected to become numerous by mid to late
afternoon with variable gusty winds in and around the storms along
with localized MVFR to IFR conditions. The storms will eventually
head east tonight with lower ceiling developing on the VFR to MVFR


Issued at 412 AM CDT Thu Jun 29 2017

Heavy rainfall once again looks quite possible across portions of
the forecast area today with PWATS of over 1.5" feeding into
southern Iowa. Portions of Taylor into Ringgold county saw several
inches of rain on Wednesday evening with the nearby counties with
an inch or two as well. Given that soils have become nearly
saturated in these locations, a flash flood watch seems reasonable
for today into tonight.


Flash Flood Watch through late tonight for IAZ081-092>094.




NWS DMX Office Area Forecast Discussion