Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 170000

Area Forecast Discussion
National Weather Service Hastings NE
700 PM CDT Wed Aug 16 2017

Issued at 657 PM CDT Wed Aug 16 2017

Updated the evening forecast to account for increased
thunderstorm activity in a small area in the south central part of
the CWA. Convection should wane over the next couple of hours as
instability decreases.


.SHORT TERM...(This evening through Thursday)
Issued at 258 PM CDT Wed Aug 16 2017

Concern in the short term involves small precipitation chances this
afternoon into early evening.

Current water vapor imagery from GOES-16 showing the mid level
trough from central SDak and into western Neb & KS continues to
slowly churn to the east. At the current speed, the trough axis
should be near the eastern edge of the CWA around sunset. Meanwhile
at the surface, low pressure was located about 30 miles NNE of OMA
with cold front extending south into northeast KS, and then curving
SW into northern OK. Dewpoints in the low to mid 70s ahead of the
front, with lower 60s behind the front across our CWA.

Widespread precipitation still ongoing with this large system,
with thunderstorms continuing along the warm conveyor belt from
Missouri to Iowa, and stratiform rain in the cold conveyor belt in
Minnesota and SDak. Wrap around showers have been working through
north central Neb this morning, and these have been working ever
so slowly towards the northwest part of the CWA. Given our CWA
will still be ahead of the mid level trough axis this afternoon
and we will still have modest instability with mu-CAPE values
around 1000 J/Kg, expect isolated thunderstorms until this evening
when trough moves east and we lose diurnal heating. While its
possible some storms could be strong, IR satellite imagery showing
cloud tops have not been cooling any more between 19 and 20Z so
all in all, they may be more of the garden variety type. Next
shift can continue to monitor this trend.

Otherwise it should be quiet overnight and during the daytime
Thursday with surface high pressure moving across the area. High
temps on Thursday should be just a tad below normal for this time of
year, while winds will west in the 5-15 mph range.

.LONG TERM...(Thursday night through Wednesday)
Issued at 258 PM CDT Wed Aug 16 2017

A quasi-zonal pattern is progged into the early part of
next week. During this period, it appears we will have several
shortwaves moving along the northern jet, which will bring
various rain chances to our CWA. The first of these looks to be
Thursday night into Friday morning. Progged instability marginal
so am not expecting severe storms Thu night. Extended models
differ in timing of subsequent waves, but at this time hard to
rule out tstm chances almost every evening and night from Sat
through next Tuesday. Might be a slight pattern change by the
middle of next week with upper ridge building into the Rockies.
This won`t necessarily keep it dry here as waves could rotate
around the ridge.

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

Plenty of uncertainty continues for the eclipse forecast,
especially regarding clouds. Both the latest operational runs of
the GFS and ECMWF point to zonal flow in the mid levels with
various disturbances pushing through the northern stream. It
always comes down to timing with no exception here. With any luck,
our CWA will be between shortwaves and the area will experience
at least partly sunny conditions. As noted in earlier discussions,
it will most likely be the weekend before we have a better handle
on this. On a brighter note, don`t see any upslope flow
conditions for next Monday which would be good news for eclipse


.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 657 PM CDT Wed Aug 16 2017

VFR conditions expected. Gusty wind should sharply decrease over
the next few hours as decoupling occurs.




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