Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Hastings NE
622 am CDT Wednesday Aug 20 2014
Short term...(today and tonight)
issued at 334 am CDT Wednesday Aug 20 2014
Showers and isolated thunderstorms continue to move through the
northwest ad northern part of the forecast area early this morning.
Surface analysis shows a surface low on the High Plains with a warm
front extending to the east near the Kansas/Nebraska border.
The warm front is expected to lift to the north early today. Expect
a few showers and some isolated thunderstorms before sunrise today.
The precipitation should end by around sunrise. Much of the day will
be dry. The pressure gradient tightens during the afternoon and
winds will increase from the south. By the afternoon the surface low
starts to move toward the east. As an upper level wave approaches
during the afternoon thunderstorms are expected to develop near the
surface low and a weak frontal boundary extending north and south
through the low. Expect thunderstorms in the west late in the
afternoon and spreading across much of the forecast area during the
evening and overnight hours. The MUCAPE across the area during the
afternoon is over 3000 j/kg with the highest early in the afternoon
and diminishing later in the afternoon. There is the chance for
some strong storms during the afternoon and into the evening hours.
The best chances for severe weather near the warm front that should
lift to the north of the area before the thunderstorms get started.
Long term...(thursday through tuesday)
issued at 345 am CDT Wednesday Aug 20 2014
Predominantly southwesterly flow aloft will continue across the
plains through the extended periods with multiple middle/upper level
disturbances bringing intermittent chances for thunderstorms to the
region. At the surface...expect seasonably warm conditions through
at least the first half of the upcoming weekend with a warm front
positioned just to our north...before a cool front is steered across
the local area resulting in a return to near or below normal
temperatures for late August.
Starting Thursday...expect plenty of instability to build across the
region as continued southerly flow near the surface advects warm and
moist air across the region. While there are some small probs for
severe weather in place across the local area by Storm Prediction Center on Thursday
.. the limiting factor appears to be lack of any significant
forcing mechanism...so kept the daytime hours dry...with forcing
from the low level jet expected to help initiate some potentially
strong storms late Thursday night across the northeastern quadrant
of the local area. As we then transition into Friday...expect an
approaching frontal boundary from the northwest to bring a better
shot for more widespread shower and thunderstorm coverage...some of
witch could be severe...with plenty of instability and upwards of
40kts of 0-6km shear. For the immediate term...expect this to be the
best shot for some decent rainfall as well as best chance for more
widespread shower and thunderstorm coverage across the local area.
As we then transition into the upcoming weekend...expect at least
the chance for showers and thunderstorms to continue...with another
uptick in activity late in the weekend as a secondary cold front
works its way across the local area in concert with an upper level
disturbance embedded in southwesterly flow. This should represent a
return to near or below normal temperatures for several days...with
continuing off and on again chances for showers and thunderstorms in
predominantly southwesterly flow aloft.
Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 615 am CDT Wednesday Aug 20 2014
A few showers have developed to the west of the terminals this
morning. There is a slight chance for some showers and maybe an
isolated thunderstorm in the Kearney area...but expect that these
should diminish as the sun comes up. There is a chance for
thunderstorms this evening. Breezy conditions are expected this