Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Hastings NE
641 PM CST Sat Jan 24 2015
Short term...(this evening through sunday)
issued at 315 PM CST Sat Jan 24 2015
..a strong clipper races just east of the region tonight with lots
of wind in its wake through tomorrow...
Aloft: no surprises...northwest flow. An embedded potent shortwave trough
was dropping out of Canada and will cross the region tonight...
deepening as it moves into the eastern USA longwave trough. A 130 M
height fall center is associated with this trough.
Surface: a clipper will dive southeast into the Midwest tonight and into
the Ohio Valley tomorrow. Its associated cool front will surge through
here tonight. High pressure will briefly drift overhead late tomorrow.
Rest of this afternoon: lots of multi-layered middle-high clouds...
but some glimpses of sun. We saw the sprinkles at vtn at 1 PM.
Radar mosaic shows patches of warm air advection sprinkles.
Tonight: weak cold frontal passage. A few sprinkles will be
scattered about and with a low probability of a measurable shower north
and east of the Tri-Cities. Winds will crank behind the front in cold air advection.
Used an even blend of the 00z/12z MOS guide and 06z/12z mav MOS
for winds. This brings a period of sustained winds of 30-35 miles per hour
from the sandhills down to the Tri-Cities. Derived gusts were
increased above the gust tool using BUFKIT.
Another mild night. Temperatures will remain above freezing through the night.
Strongest winds will occur 10pm-10am over S-central Nebraska and 10am-
4pm over north-central Kansas.
Sun: windy...with the strongest gusts forenoon. There should be
substantial stratus/stratocu in the cyclonic air/thermal trough.
Spotty sprinkles/flurries linger east of Highway 281. About 10f cooler
Long term...(sunday night through saturday)
issued at 315 PM CST Sat Jan 24 2015
Mainly a temperature forecast for the long term.
Numerical models are generally consistent with the overall
synoptic patter and in fairly good agreement with the overall
larger features...with minor differences among smaller features.
We kick off the long term Sunday night with a synoptic pattern of
a negatively tilted upper level ridge in the western United States
stretching from the southern rockies to the Pacific northwest...
and a pronounced trough over the eastern half of the United
States...placing US within northwest flow. A strong upper level
jet will be in the process of departing to the east...with speeds
of well over 100 kts over the Central Plains...near the exit
region. At the surface...a frontolytic back door cold front may
stall and still be lingering over or near the southwestern
County Warning Area...but wind from the southwest/west should begin kicking up by
the overnight hours as warm air advection ensues. This indicates
an relatively early low temperature for Sunday night...with rising
temperatures probable during the overnight.
To be right up front...this looks like a dry long term until
Friday night/Saturday...as forecast soundings continue to
advertise seasonably typical dry low and middle levels. A closed low
off the Southern California coast will eventually be drawn into
the northern stream and become an open wave trough that rides over
the northern side of the western ridge. This will weaken and
dampen the ridge as it moves east. The dampening ridge axis will
move onto the Great Plains Tuesday...with the ridge axis crossing
the County Warning Area Tuesday night. The aforementioned wave that was
responsible for dampening the ridge will cross the County Warning Area sometime
Wednesday afternoon/evening. Not expecting measurable
precipitation with the associated cold front passage as it has
been established that the ambient environment continues to be
quite dry...but a sprinkle or flurry may not be completely out of
By late work week on Thursday/Friday. The western ridge becomes
re- established over the western United States...amplified by a
Pacific trough to the west over the Pacific Ocean. An embedded
weakness will move east within the southern stream and by the
weekend will become a closed low as it enters the Baja California. For
US...this synoptic scenario means northwest flow aloft for late
work week and heading into the weekend...with not a lot of
moisture to work with. With this pattern...there can certainly be
perturbations that could kick up a sprinkle or flurry...but we are
not going to see any kind of meaningful precipitation for the long
term. A trough at the end of the long term...in the Friday
night/Saturday time frame...will introduce much cooler
temperatures and could induce some light snow...perhaps a mix in
our south...as fairly strong cold air advection is anticipated.
Highs are forecast to be mainly in the 30s for Saturday.
As far as temperatures...we continue to be mild for this time of
year for the entire long term forecast. With the approach of the
ridge on Monday into Tuesday night...the high temperatures on
Monday and Tuesday will be noticeably warmer on Monday and Tuesday
as highs reach the upper 50s/60s. A separate fire weather section
has been introduced for Monday with the combination of warmer
temperatures...subsequent lower relative humidity...and stronger
surface wind speeds. Wednesday will be another quite mild day
ahead of the aforementioned trough with highs in the upper
50s/60s...and then a cool down for Thursday behind the
trough...but still a bit above the normal of 35 to 40 degrees for
this time of year with highs in the middle 40s to near 50. The cooler
trend continues as a reinforcing shot of even cooler air is
forecast for Saturday...behind a cold front passing through Friday
night/early Saturday morning. The operational run of the European model (ecmwf)
predicts 850 mb temperatures for Saturday in the minus 9c to minus
15c range. I raised low temperatures a fair amount for most days
until Saturday as I stuck to consraw for the most part...as it
tends to do better with situations where we are much above normal.
For highs...I generally edged the temperature up a couple
degrees...using the initialized superblend as a starting
point...except for Saturday...where I kept temperatures a little
cooler behind the cold front.
Aviation...(for the 00z kgri/kear tafs through 00z Sunday evening)
issued at 632 PM CST Sat Jan 24 2015
The primary concern tonight will be the wind. A clipper system
will pass off to our northeast tonight and a strong northwest wind
is expected through the night into the day on Sunday. There will
also be a few rain showers around the area tonight and these
should have largely moved east by daybreak Sunday morning.
Ceilings will lower through the night and could see MVFR ceilings
by Sunday morning.
issued at 315 PM CST Sat Jan 24 2015
Monday could be a near-critical fire weather day as the surface
pressure gradient could still be quite strong. A surface high
centered over the northern plains will scoot to the east during
the day...sending a strong pressure gradient down into the Central
Plains as the ridge axis moves east. With wind speeds trending
higher along with warmer temperatures...the southwestern County Warning Area will
be especially under the gun for lower relative humidity and
stronger wind gusts. We are looking at relative humidity bottoming
out in the 20 to 25 range and northwest wind gusts of 25 to 30 miles per hour
for at least the southwestern County Warning Area...roughly southwest of a line
from Elwood Nebraska to Osborne Kansas.