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Area forecast discussion 
National Weather Service Des Moines Iowa
1210 PM CDT Thursday Jul 30 2015

Short term /today/...
issued at 255 am CDT Thursday Jul 30 2015

Few concerns today as low departs over southern Canada and a weak
front drops south and dissipates by middle morning. Overall weak
warm air advection will return by late afternoon with west-northwest winds at
h850 and warming h850 temperatures to 17c east to 19c west. Though surface
dew points will be lower today...temperatures will be similar or modestly
warmer with mixing in the afternoon with just a few fair weather
clouds around 7-8kft. Highs expected to reach the lower 80s in the
northeast to the upper 80s to near 90 from central to southwest
areas. Winds will mix to 18 to 23 miles per hour across the east during the
afternoon which should also help lower dew points and result in a
nice day across the region.

Long term /tonight through Tuesday/...
issued at 255 am CDT Thursday Jul 30 2015

Main forecast concern was focused on Saturday night and with
temperatures through the extended period. Leaned toward GFS/European model (ecmwf)
for precipitation trends and temperatures through early next week.

Tonight into Sunday...large upper level ridge remains entrenched
over the southwest to south-central United States and places
Iowa within northwest flow aloft through early next week. Surface
high continues over the state through Saturday with good mixing
developing Friday afternoon. Mixing to around 850mb seems
reasonable and will push temperatures back close to 90 over central to
southern Iowa and in the middle 80s over the north. Drier dew
points will aid in the warm up as they range from upper 50s north
to upper 60s south. Bumped up wind speed and gusts through the
afternoon hours tomorrow with the winds atop the mixed layer
around 25-30 knots and much of that should materialize at the
surface.

Some weak convergence and middle-level vorticity may spawn some
isolated showers and thunderstorms late Friday afternoon over the
far south in response to a very weak shortwave moving into
northern Missouri. Have introduced slight chance probability of precipitation b/T 21z
Friday to 00z Saturday. However...if anything does develop it will
be very high based and not anticipating much quantitative precipitation forecast.

A more significant potential for thunderstorms is Saturday night
into early Sunday. European model (ecmwf)/GFS and even the NAM have come into very
good agreement with timing and placement of precipitation and forcing
during the evening Saturday night. Severe threat remains limited
due to lack of strong shear present even with some moderate
instability available. Plus...the forcing with the shortwave is
weak and somewhat disorganized. There is a threat of heavy rain
with precipitable water values increasing to 1.5-2.0 inches and
warm layer cloud depths to around 3700m Saturday evening. Albeit
not anything like earlier this week for heavy rain...but still a
decent signal and confident enough to at least increase probability of precipitation
Saturday evening.

Sunday into Tuesday...another weaker shortwave cuts across northern
Iowa late Sunday night into Monday and have some chance probability of precipitation going
over the northeast. Through the remainder of the forecast...extended
models in disagreement with timing of shortwaves and low confidence
with any timing and location of precipitation after Sunday.

&&

Aviation...30/18z
issued at 1210 PM CDT Thursday Jul 30 2015

VFR conditions expected through the taf period. Warm advection will
be responsible for some scattered middle/high level clouds. After 03z a weak
cold front will sink south across the taf locations. This will
bring a scattered-broken deck between 080-100kft which is expected to diminish
late in the forecast period. Surface wind will become northwest after 03z with the frontal passage
and may increase after 13z to 10-15kts.

&&

Dmx watches/warnings/advisories...
none.
&&

$$

Short term...rev
long term...podrazik
aviation...fab

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