Scientific Forecaster Discussion
fxus63 kgid 241706
Area forecast discussion
National Weather Service Hastings NE
1206 PM CDT sun Sep 24 2017
Short term...(today and monday)
issued at 335 am CDT sun Sep 24 2017
As of 3am, the cold front was located along along a line
extending from near McCook to Kearney to Albion. This front is
gradually lifting northward and will continue to do so through the
morning. This, along with increasing clouds and showers/T-storms,
will make for a large spread in temperatures today. Areas near
Highway 81 are expected to reach the upper 80s, while the Tri-
Cities will only reach the 70s, and areas like Lexington and Ord
may only reach the low 60s!
Rain showers are currently ongoing across western portions of our
forecast area, and this band will slowly expand eastward this
morning. That said, I don't expect to see much, if any, rain east of
Highway 281 until afternoon when models show increasing 500mb
vorticity advection and upper level divergence. Short term models
agree with this assessment. Through the day today, there will be
around 500 j of MUCAPE...enough for a few rumbles of thunder, but
I expect any thunderstorms to remain isolated in coverage.
Another uptick in shower/thunderstorm coverage will occur in the
late evening and overnight as convergence along the 850mb boundary
increases. This will likely set up in a persistent band, the
location of which will be difficult to predict until it develops.
Where this band sets up, 2 to 3 inches of rain is possible.
Rainy and cool conditions will continue into Monday. The cold front
will continue to push southeastward across the area, and high
temperatures will range from the mid 50s in the northwest to upper
60s in the southeast. Scattered showers are expected to continue all
day, with the area of best coverage gradually shifting southeastward
with the front. The threat for any thunderstorms really starts to
diminish during the afternoon, so i've trimmed back the forecast to
only showers beyond there.
Long term...(monday night through saturday)
issued at 335 am CDT sun Sep 24 2017
Upper level wave ejecting out/splitting from western trough will
keep the steady rain showers going Monday night for much of the
forecast area although things will start to diminish after midnight
as favored area of upper level jet pulls north of the region.
Continued with high rain chances Monday night and then tapering
chances Tuesday from northwest to southeast during the day.
Clearing will work its way across the forecast during the day
Tuesday from west to east. Temperatures will be cool even when the
sun reappears with highs only in the 60s. Slight moderation in
temperatures by Wednesday and through Saturday with daily highs
averaging the upper 60s to lower 70s. The forecast area is in a
northwest flow regime all week and that should keep things dry with
a cool early fall-like feel. Current low temperature forecast for
wednesay morning has lows in the lower 40s in northern and far
western forecast area. With clear skies and light winds lows may dip
to the upper 30s in favored colder spots like valley, Greeley and
Dawson counties. Don't see frost as an issue but lows are Worth
watching. Another weak, but dry front slides through the area later
Thursday/early Friday and shifts winds to the north for a time.
Saturday morning could also be a bit cooler than lower 40s in the
north/northeast part of the forecast in valley, Greeley and Nance
Looking a bit further, the upper flow wants to transition to
southwest flow in the first few days of October suggesting somewhat
warmer temperatures to start the month.
Aviation...(for the 18z kgri/kear tafs through 18z monday)
issued at 1157 am CDT sun Sep 24 2017
Varying conditions are forecast through the taf period with
regards to timing of low clouds along/behind a cold and when the
terminals will see the best chances for rainfall. At 17z the cold
front was located just west of kear with cloud heights varying
from MVFR to IFR. The cold front and low clouds will gradually
work east the next 24 hours, with IFR or LIFR conditions possible
at times Monday. An elongated band of rain associated with the
boundary and ahead of an upper low pressure system will gradually
shift east over the terminals with the best chances heading into
the evening through Monday based on the latest short term models.