471
FXUS63 KGID 151107
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
607 AM CDT Tue Aug 15 2017

.SHORT TERM...(Today and tonight)
Issued at 322 AM CDT Tue Aug 15 2017

Thunderstorms continue to move just to the north of the forecast
area this morning. Surface analysis shows a weak front just to the
north of the Kansas/Nebraska border.

Once again the models are not handling the current thunderstorms
very well. The upper level ridge is moving to the east this morning
and an upper level wave will be affecting the area this afternoon
and tonight. At the surface, the models have a few different
scenarios with the current front in southern Nebraska. The result is
similar whether the front moves to the north as a warm front today,
or whether it just washes out and another front develops to the
northwest of the forecast area this afternoon. Either way, there is
expected to be a front to the northwest of the forecast area this
afternoon and it is supposed to move to the southeast during the
late afternoon and evening.

As the upper level wave approaches this afternoon there will be some
convection that develops along the front and should move into the
area this afternoon and evening. The other player in the development
of storms will be some clearing across the forecast area. There are
already some juicy dew points across the area and a good south wind
will bring in some additional low level moisture. The sun early this
afternoon will create some instability and there could be some
thunderstorms developing ahead of the front as it moves into the
area this afternoon. The main thing for this afternoon and tonight
is that there are pretty good chances for precipitation. As for
severe weather, there is MUCAPE of 2000 to 4000 j/kg depending on
the model and there is some shear, but that too is dependent on the
model. There could be some severe in the afternoon and into the
evening, but the models decrease the CAPE during the evening. At
that point expect there to be more rain than severe and with slow
moving storms there could be some heavy rain.

.LONG TERM...(Wednesday through Monday)
Issued at 350 AM CDT Tue Aug 15 2017

Overall...a gradual warming trend is anticipated through the
extended periods with temperatures returning to near or slightly
above normal values by early next week. In addition...there will be
multiple...mainly small chances for thunderstorms...with many
locations likely to remain dry beyond Wednesday.

With that in mind...global models are in fairly good agreement at
the start of the extended periods lifting a broad trough of low
pressure across the local area Wednesday...which will likely be the
best chance for fairly widespread shower and thunderstorm coverage.
While there is relatively modest shear and instability throughout
the day Wednesday...which would normally present the chance for some
strong to marginally severe thunderstorms...lots of cloud cover and
correspondingly below normal temperatures will likely limit surface
based instability...and at this time the better chance for and
strong or severe thunderstorms appears to be east of the local area.

As the aforementioned upper level trough then shifts east later in
the week...a primarily zonal flow pattern will set up across the
local area...resulting in multiple quick passing disturbances and a
slight warming trend across the local area. Later in the weekend and
early next week...things get a bit more interesting as a weak ridge
followed by more zonal flow is forecast by the extended models. This
should allow temperatures to return to near or above normal values
by early next week...with additional small chances for thunderstorms
from time to time...although nothing certain at this time.

.ECLIPSE...

A total Solar Eclipse will occur Monday August 21st around 1pm CDT.

As previously mentioned...things get a bit more interesting late in
the weekend and early next week as it now appears a progressive
zonal flow pattern could possibly be setting up across the local
area. While this is by no means a guarantee more than 5 days
out...this sort of pattern lends itself to some passing clouds and
showers from time to time...so it will need further monitoring. But
at least climatologically speaking...the timing of the Eclipse
locally...during the early afternoon hours...should lend itself
to a good shot of mainly cloud free skies and limited shower
activity...so opted to reduce cloud cover and trim pops for the
early afternoon hours Monday from those given with the blended
model solutions.

&&

.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Wednesday)
Issued at 605 AM CDT Tue Aug 15 2017

Thunderstorms are possible through much of the period, but the
better chances will be during the afternoon and overnight. This
morning there is some stratus around with some lower ceilings and
visibilities. It has been in an out in the past hour and with the
sun coming up it should not last too long.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&

$$

SHORT TERM...JCB
LONG TERM...Rossi
AVIATION...JCB