Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Hastings NE
657 PM CDT Monday Jul 25 2016
Short term...(this evening through tuesday)
issued at 346 PM CDT Mon Jul 25 2016
Aloft: zonal flow was along the US-can border with a weak trof
over the pac northwest and subtropical highs over the desert SW and
Carolina's. A weak/subtle shortwave trof will eject out of the pac
northwest across the nrn rockies and will be over Wyoming by sunset tomorrow.
Overall...west-northwest flow will prevail here.
Surface: high pres was over Iowa. The next cool front was dropping
thru the Canadian prairies. The Iowa high will drift into the Ohio Vly
and Great Lakes thru tomorrow. The cool front will sag into the
nrn plains and be located west-east across South Dakota by sunset Tue.
Sct tstms are developing over the mtns out to the west. They should
remain there tonight. While they will move off the mtns as
usual... the atmosphere over the fcst area is stable. The low-lvl
jet will develop west of the fcst area tonight...and will be
collocated with the moist tongue over the High Plains. At this
time...am not expecting any of these storms (or their remnants) to
survive the trip east into the fcst area.
Tonight: clear to start...but anvil blow-off from upstream tstms
should result in patches of cirrostratus moving in.
Overall...skies should average M/clear...but could turn p/cloudy
after midnight in some locations.
Pleasant with near normal temps in the 60s and relatively
Fog/stratus: one concern is the potential for fog/stratus
tonight. The mesoscale convective system over Kansas last night left a lot of low-lvl mstr
around. It is quite disconcerting that mhk and svrl other nearby
stations still have scattered low clouds around 2k ft at 3 PM...and
winds are currently from the southeast and will remain from the southeast.
Tue: barring any fog/stratus to start the day...it will be very
nice. Highs near normal (upr 80s-low 90s). We do have a slight
chance of tstms over the extreme northwest fringe of the fcst area after
5 PM...but it's unlikely.
Long term...(tuesday night through monday)
issued at 346 PM CDT Mon Jul 25 2016
Aloft: zonal flow will remain thru Wed. A weak shortwave trof will
emerge out of the pac northwest trof and cross the Dakota's Tue night. A
stronger trof with greater synoptic forcing will follow it...
crossing the nrn/cntrl plains Wed. Some modest amplification will
then occur introducing northwest flow Thu-sun. The approach of a strong
trof and an 80-90 kts upr-lvl jet streak into wrn Canada will nudge
the wrn USA ridge onto the plains sun with SW flow developing Mon
with its passage.
Surface: the nrn plains cool front will gradually sink S and should
be S of the fcst area by sunset Thu...though its forward progress
could be masked by mesoscale convective system outflows at times. Weak low pres could
develop along the front Thu-Fri over the mid MS Vly. Canadian high
pres will gradually slip into the srn plains Thu-Fri...and then
probably depart into the MS Vly Sat. A strong pac cool front and
will be moving in off the pac this weekend...and this should force a
warm front to develop across the nrn/cntrl plains. The 00z/12z ec
and its 00z ensemble mean have the cool front emerging into the
Dakota's and neb next Mon.
There are multiple opportunities for sct tstms Tue night thru sun.
Some beneficial soaking rains could be in the offing as northwest flow
usually delivers mtn/High Plains tstms southeast into the fcst area via
low-lvl upslope flow and weak shortwave trofs aloft.
Trying to be specific svrl days in advance is like chasing after
the wind. Suffice to say rain chances will improve this week...
but as usual...everyone probably will not benefit.
For what it's Worth...the ec ensemble quantitative precipitation forecast probs have the greatest
likelihood for Wed into Wed night which is about 24 hrs delayed
from what we saw late last week.
Temps will be near or below normal...a nice reprieve from the
heat of last week.
Aviation...(for the 00z kgri/kear tafs through 00z Tuesday evening)
issued at 651 PM CDT Mon Jul 25 2016
VFR conditions are expected. There is an outside chance of some
MVFR stratus moving in from the southeast, but this has not been
included in the forecast as numerical models are not indicating
this to a degree that confidence is high enough to include in the