Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Sioux Falls South Dakota
300 PM CDT Tuesday Jul 22 2014

Short term...(this evening through wednesday)
issued at 300 PM CDT Tuesday Jul 22 2014

Will go ahead and keep the mention of isolated to scattered
convection going into the very early evening hours across our far
southern zones...including the Sioux City area. This activity
developed earlier this afternoon toward north central Nebraska along middle
level convergence which has since waned. However a strong 850mb
frontal boundary is positioned in our far south late this afternoon
which will likely help to keep the activity going. Otherwise it
should be dry tonight as surface high pressure Ushers in ever
increasing drier air from the north. Any convective chances tonight
should stay west of our forecast area tonight. If convection does
develop in the Western probably a little thin on the sky
cover tonight as cirrus will then move across the forecast area.
925mb temperatures have not changed much from model run to
did not have to alter lows much at all.

Could be some middle clouds in our western zones Wednesday morning. But
otherwise kept things dry with a seasonably mild day in the upper
70s to middle 80s.

Long term...(wednesday night through tuesday)
issued at 300 PM CDT Tuesday Jul 22 2014

Wednesday night will see the warm advection pattern and the
potential for thermal lift related least in our South Dakota
area. This pattern will develop as the strong Pacific wave eats into
the upper ridge. Moisture and especially instability will be slow to
return...but the threat should reach Interstate 29 by daybreak
Thursday...continue over the area Thursday and become enhanced
some...especially easy...Thursday night into Friday as the strong
ridge flattening wave approaches. Saturday should then be dry.
Modestly cool temperatures will warm somewhat through Friday then
should still be mild Saturday especially with more sunshine. Of
course with the main upper ridge forced back well southeast of the
northern plains...the hot and sticky air of yesterday will not make
it back.

Sunday will bring the passage of a secondary wave bringing cooler
air and some fairly small chance of showers or storms northeast as a
pocket of even cooler air aloft passes by. This second wave will
then help dig a large scale trough over the Great Lakes and eastern
USA and leave our area in a dry and modestly cool northerly flow
early next week.


Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1226 PM CDT Tuesday Jul 22 2014

Cumulus clouds are moving southward in a band in southwest Minnesota...
extreme northwest Iowa and immediate adjacent areas at this time.
Most of the clouds are based in the MVFR category...and will
primarily affect extreme northwest Iowa through middle afternoon before
either dissipating or mixing deeper into the VFR category.
Otherwise conditions will be VFR through 18z Wednesday.


Fsd watches/warnings/advisories...
South Dakota...none.


Short term...mj/
long term...

National Weather Service Glossary of Abbreviations