Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Des Moines Iowa
526 am CST Wednesday Mar 4 2015

Short term /today/...
issued at 338 am CST Wednesday Mar 4 2015

High pressure system will begin to push into Iowa through the day
today...with cold air advection continuing across the area. Light ongoing snow in
far southwestern County Warning Area will continue to push south and diminish
through the morning hours. Across the far northeast may see a brief
period near 12z where wind chill values drop near/blow 20 below zero
as temperatures drop and winds remain stronger in that area.
However...this will be brief as temperatures will warm quickly and
will hold off on Wind Chill Advisory. Weak surface boundary will
push south through the day and have added flurries to the forecast
in the afternoon as forcing will be very weak...though with cold air advection
soundings indicate enough saturation in dgz to warrant flurry
mention...especially with ongoing light snow in central Dakotas
at this time. Have kept temperatures near going...though may be too cold
with mixing...but expect clouds through much of the day to keep
temperatures cooler.

Long term /tonight through Tuesday/...
issued at 338 am CST Wednesday Mar 4 2015

Broad northwest flow is expected across the area for much of the
forecast period with some transition toward more zonal by the end
of day 7. Despite the continuance of the upper flow that has been
predominant through February...the primary storm track will be
farther north and east with Iowa seeing only glancing blows of
cooler air after the current polar airmass exits.

Looking at tonight...will see the approach of surface ridge with
Arctic airmass across the state. One more night of below zero
readings is expected for much of the area under clear skies and
weakening winds. Wind chills are expected to drop to around 20
below late tonight and will be breaching into advisory criteria
for a brief period around daybreak on Thursday. Have held off on
headline issuance as it is marginal and let the dayshift look to
see if the values change much.

Thereafter...warm advection will take over into Thursday and
Friday as thermal ridge approaches from the plains. Likely to see
non-diurnal temperature curve on Thursday night with increasing
south winds overnight. There will be some minor cooling into
Saturday behind a weak boundary but readings will rebound into
early next week as strong west to southwest flow develops
transporting much warmer air into the Midwest. Highs well into the
50s seem likely by Tuesday for all of the County Warning Area with some 60s
possible. There will be little threat of precipitation for the
duration of the extended.


issued at 517 am CST Wednesday Mar 4 2015

High pressure will keep conditions VFR through period. Winds will
be from the northwest...with gusts to 20kts through 00z. Winds
will decrease after 00z through remainder of period.


Dmx watches/warnings/advisories...



Short term...awb
long term...cogil

National Weather Service Glossary of Abbreviations