Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Des Moines Iowa
648 am CDT Monday Sep 1 2014

issued at 317 am CDT Monday Sep 1 2014

Cold front moving across Iowa will pass to the southeast tonight
with high pressure building in behind it. The next frontal system
will move through the upper Midwest about Friday.


Short term /today/...
issued at 317 am CDT Monday Sep 1 2014

Currently there is convection re-firing along the Highway 20
corridor in an axis of warm advection ahead of the cold front that
is situated across the far northwestern corner of Iowa. The slow
moving frontal boundary will shift across central Iowa today. The
northern portion of the front will accelerate faster than the tail
end aided by a shortwave moving into Wisconsin. The front will lay
out across the east and south east and at 18z should be from roughly
northeast Wisconsin southwest to Waterloo then to Lamoni. At the
end of the forecast period the front will be entering Michigan to
the north then extending back to around Ottumwa. There is decent
convergence along the front and pretty impressive forcing as well.

Currently there is expansive cloud cover across Iowa but south of
Highway 20 it is mainly middle and high level cloud cover. Once the
sun comes up I would expect enough heating to destabilize the
atmosphere ahead of the front and storms to fire across the east and
southeast. Shear is enough for strong updrafts and some storms will
be capable of large hail and especially damaging wind. By 00z the
threat will be confined to the far southeast at most. I have
trended probability of precipitation down from northwest to southeast through the afternoon hours. As for
temperatures...highs will be in the middle 70s behind the front with lower to
middle 80s ahead of it. The speed of the front being as slow as it is
it is hard to say how much of the County Warning Area will be in the 80s but for now
I have the southern third or so of Iowa around 80.

Long term /tonight through Sunday/...
issued at 317 am CDT Monday Sep 1 2014

High pressure will bring drier air into the region tonight and
Tuesday...though not significantly cooler as the airmass is Pacific in
nature. As the high moves off to the east expect to see some warm air advection
thunderstorms develop on the back side.

Rising heights will be in place across the central U.S. For middle
week with the warmest day likely to be Thursday with upper 80s to lower
90s across the County Warning Area along with dew points in the 70s.

The next cold front will move through late night week with another round
of thunderstorms. The upper flow buckles more with this feature
and that will likely bring down cooler air than the past few
fronts have, dropping highs into the 70s...even a few upper
60s...over the weekend. In the longer not expect to see
a strong cooling for a least until after the Bermuda
high backs off with the approaching long wave trough toward the
middle of next week.


issued at 0648 am CDT Monday Sep 1 2014

Cold front slowly pushing into northwest Iowa will move across eastern taf
locations this afternoon. Low clouds will linger a bit longer this
morning but still expect VFR conditions this afternoon. Thunderstorms and rain will develop
ahead of front but coverage should only be isolated to widely scattered so just
put vcsh in tafs for now. Surface wind with become northwesterly around 10 kts.


Dmx watches/warnings/advisories...


Synopsis...MS Sep 14
short term...fab
long term...MS Sep 14

National Weather Service Glossary of Abbreviations