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Area forecast discussion 
National Weather Service Des Moines Iowa
633 am CDT Sat Jul 4 2015

Short term /today/...
issued at 247 am CDT Sat Jul 4 2015

High pressure still in the area to push off to the southeast today.
A weak upper level wave to push into the region late today...but
little moisture with it so still expect dry conditions. Winds to
shift around to the southwest aloft...with weak warm air advection so should see
warmer temperatures today than in the past few days. Still expecting some
of the smoke to work its way into the area in the higher levels may
create some haze and again could impact maximum temperatures a bit. Some areas
to the north had some of the smoke make its way to the surface
creating lowered visibilities and air quality conditions. These
conditions are expected to work to the south and east today...and
could push into extreme northern/northeastern portions of the County Warning Area by
late today which could bring visibilities into the 2 to 5 mile
range.

Long term /tonight through Thursday/...
issued at 247 am CDT Sat Jul 4 2015

For the 4th of July activities tonight...dry weather can be
expected with mostly clear skies...a south wind near 5 miles per hour and
comfortable temperatures. Sunset tonight is at 852 PM.

Surface high pressure will shift east of Iowa tonight. Shortwave
energy moving through the main westerlies will sharpen an upper
trough over central Canada. In response to height falls
aloft...surface low pressure will deepen in the northern plains
with southwesterly flow increasing. Ahead of an advancing cold
front...highs will rebound to the 80s aided by compressional
warming.

This front will provide a focus for showers and thunderstorms
Sunday night through Monday. Forecast models forecast precipitable
water values near 2 inches which is over 2 Standard deviations of
precipitable water climatology. Heavy rain and localized flooding
will be a risk particularly where moisture transport is maximized
near the low level jet and showers and thunderstorms move over the
same areas. Strong to severe thunderstorms could also produce
damaging winds with 0-3km bulk shear near 40 kts and mu cape near
2000 j/kg. Lapse rates will be sufficient for a marginal hail risk
where stronger updrafts are realized. Precipitation will taper
from northwest to southeast across the state Monday night.

Surface high pressure will build over the Midwest on Tuesday
bringing a cooler and drier airmass to the region. High
temperatures are expected to be about 10 degrees below normal for
this time of the year.

Southerly flow returns to the state Wednesday as the high builds
east. Weak isentropic upglide along with daytime heating will
bring chances for scattered showers and thunderstorms.

An upper ridge will be building across the Southern Plains late
in the week with northwest flow aloft over Iowa. Shortwaves
rounding the ridge will aid thunderstorm development in the
northern plains with showers and thunderstorms tracking southeast
through the corn belt.

&&

Aviation...04/12z
issued at 633 am CDT Sat Jul 4 2015

Mainly VFR conditions expected throughout the taf forecast period.
May have a scattered low VFR cumulus deck this afternoon. Winds should shift
around to the southwest to south/southeast through the period.
Concern over some haze and possible visibility reductions from smoke
making its way to the surface across the far north today.
Confidence is low that it will make it into the County Warning Area especially
given winds turning more southerly...so have left at p6sm for now.

&&

Dmx watches/warnings/advisories...none.

&&

$$

Short term...beerends
long term...angle
aviation...beerends

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