Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Aberdeen South Dakota
317 PM CDT Sat Aug 30 2014
Short term...tonight through Monday night
Stratus deck that plagued the eastern counties much of the day is
finally turning into more of a scattered/broken stratocu field...and has
held temperatures back a few degrees as well. Have adjusted temperatures a bit
through 00z this evening to account for this.
Otherwise...focus is on thunderstorm chances tonight then again
Sunday afternoon/evening. Surface low beginning to take shape over
Wyoming with low level moisture streaming northward across western
South Dakota with dewpoints approaching 60 degrees. Models really have not
backed off much from previous runs. Still expecting storms to
move/develop across western South Dakota later this afternoon/evening and
push into north central South Dakota. Hi res models all show bulk of the
activity spreading into southern ND...with varying degrees of
activity on the southern flank across South Dakota. With impressive low
level jet moving across the region overnight...expect some degree
of activity to spread across the County Warning Area overnight. Although...the
severe threat remains highest over western/central South Dakota.
Will then look to Sunday afternoon/evening for next round of
thunderstorm chances. Best instability still sets up east of the
area Sunday afternoon...from Minnesota into Iowa and eastern
Nebraska. Far eastern County Warning Area...mainly east of I-29 does develop some
decent instability and could see some storm development tomorrow.
But the main show will definitely set up east of here.
Aside from these two main thunderstorm chances...will also have to
watch the shortwave activity for Sunday night and Monday
afternoon/evening. Models beginning to show more Post frontal
precipitation Sunday night...associated with the main upper wave as it
slides across the area. Somewhat similar setup Monday night
although this particular wave appears a bit weaker.
Long term...Tuesday through Saturday
Generally flat/fast middle level flow is expected to continue for the
most part across the northern Continental U.S. Through the long term. The
main weather maker should cross the area somewhere in the Thursday
through Friday time frame. The European model (ecmwf)/Gem/UKMET are faster than the
GFS and thus drier for Thursday through Friday. Model blend gave
somewhat high probability of precipitation Thursday night and Friday but decided to trend
toward faster consensus that way we can take out probability of precipitation if faster
trend continues. Overall temperatures are expected to average near
to a little bit above normal.
18z tafs for the kabr...Katy...kpir and kmbg terminals
The low clouds over the east should dissipate early this
afternoon...leaving VFR conditions at all taf sites through most
of tonight. More low ceilings could develop toward Sunday morning in
moist southeast flow.