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Area forecast discussion 
National Weather Service Hastings NE
335 PM CDT sun Jul 5 2015

Short term...(this evening through monday)
issued at 332 PM CDT sun Jul 5 2015

With a cold frontal boundary sliding through the region during the
short term period...uncertainties lie in exact timing and resulting
precipitation chances associated with the front.

The synoptic setup across the Continental U.S. Features an upper level low
pressure system across the southeast and an upper level ridge across
the Desert Southwest. The jet stream lies well to the north of the
Central Plains with nearly zonal flow across the northern half of
the Continental U.S. And an upper level low over Hudson Bay. Water vapor
imagery shows an upper level wave in British Columbia...a spoke of
the aforementioned low...while moisture is driven up and over the
top of the ridge axis. At the surface strong warm air advection is
occurring across the forecast a result of strong
southerly winds. A surface low has begun to deepen throughout the
Front Range of The Rockies...attached to the vertically stacked
low over Quebec and the Hudson Bay.

As the upper level wave dives southeast from British Columbia...this
will be the driving force to send the surface low and cold front
through the region. Timing of the cold frontal passage is fairly
uncertain as latest model runs have begun to slow frontal passage down
compared to previous runs. Believe that frontal passage will occur across the
Tri-Cities in the 9 to 15z time frame. However...while precipitation
is possible and expected somewhere across the forecast area...we
stand the chance at being on the losing end of precipitation. First
and foremost the main energy of the upper level short wave will
slide further north of the area...where the best jet lift will be.
Also timing of the frontal passage will indeed hinder our
precipitation capability by not tapping into the peak heating of the
day. So regarding precipitation chances...short term model solutions
such as the hrrr and the WRF are more aggressive with
precipitation but neither are initializing well with current
conditions. Other models such as the NAM...GFS and European model (ecmwf) solution
vary considerably on timing and location of the heaviest bands of
precipitation...but are in agreement on lesser quantitative precipitation forecast amounts overall
across the area. In fact...most solutions are leaning towards a
quarter of a inch of precipitation or less. As the front clears
most of the forecast area by early afternoon...peak hitting will
initiate thunderstorms...most likely south and east of the
forecast area.

Since the front has seemed to slow down from previous runs...went
ahead and bumped up high temperatures just slightly to be more in
line with model guidance. As normal with frontal passage...strong south winds
are expected ahead of the frontal boundary with strong north winds

Long term...(monday night through sunday)
issued at 332 PM CDT sun Jul 5 2015

A pleasant start to the extended periods is expected across the
local area as the front expected to push across the area on Monday
will be south of the local area by Monday night...with cooler and
drier air expected in its wake. While there may be a few lingering
clouds across the area...Tuesday could be one of the nicer days of
the extended...with seasonably cool temperatures in the 70s and
lower 80s...light northeasterly winds...along with mainly cloud free

While the upper level level flow pattern will be generally weak and
mainly zonal through the upcoming week...allowing for continued
pleasant and seasonal temperatures...expect multiple upper level
disturbances to cross The Rockies from the parent low pressure
system across central California...bringing several...mainly
small...chances for showers and thunderstorms to the local area
Wednesday through Sunday. While it definitely will not be wet every
single period of the extended...there will be several rounds of
showers and thunderstorms across the local area...with the best
chances during the evening and overnight hours as enhanced by the
low level jet.

Late in the extended...high pressure across the southeastern US is
expected to retrograde westward into the plains...which will likely
resulting in warming temperatures to above climatology over the upcoming
weekend...and for a potentially drier stretch of weather next week.


Aviation...(for the 18z kgri/kear tafs through 18z Monday afternoon)
issued at 1149 am CDT sun Jul 5 2015

Strong southerly winds will continue through the afternoon and
evening hours before slightly decreasing overnight. However...a
cold front approaching from the northwest will aide in keeping
wind speeds above 10 kts from the south. Although timing of the
frontal passage is not quite certain...winds will begin to shift
from the south to west by the early morning hours before finally
shifting to the north by middle morning. Lowered ceilings are
expected with this frontal passage as showers and possibly
thunderstorms are likely to be in the vicinity if not over the
taf site by middle morning.


Gid watches/warnings/advisories...


Short term...saltzman
long term...Rossi

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