FXUS63 KGID 191133

Area Forecast Discussion
National Weather Service Hastings NE
633 AM CDT Sun Aug 19 2018

.SHORT TERM...(Today and tonight)
Issued at 358 AM CDT Sun Aug 19 2018

Duration of the rain is primary forecast concern in the short term.

Upper air analysis and water vapor imagery showing a negative tilted
trough moving off the Rockies and into the Plains. 500mb, 12-hour
height falls of 40 meters noted ahead of the trough. Widespread
showers and tstms occurring all the way from NDak to Texas. At the
surface, low pressure was located over northern SDak with a
trough extending south into the middle of our CWA. Dewpoints were
in the mid/upper 60s. As of 07Z the pcpn was moving northeast and
extended from Gosper to Jewell Co and all points south. A few
rogue showers have popped up ahead of the main pcpn shield. Only a
few lightning strikes noted at this time in and near our CWA. SPC
meso page does show enough instability in the area for convection
although not concerned about severe storms as deep layer shear is

Models continue to move the upper low over our CWA by 00Z tonight
and then advance it slowly east, placing it near eastern Iowa by
Monday evening. Best timing for synoptic forcing over our CWA looks
to be through early afternoon today as depicted by the omega values
on cross and time height sections. Comparing several of the
operational and CAM models, they generate more widespread rain
through the early afternoon and then continue this in the eastern
CWA into the evening while bringing more wrap around precip into
the western CWA. This seems reasonable with the upper low
overhead. Some locations could see a break for a few hours between
the initial rain and the wrap around precip. Due to the slow
nature of this system, the wrap around precip is expected to last
into Monday before gradually ending from west to east. Would
expect many locations to receive an inch before all is said and
done with some places topping 2 inches. Temperatures won't rise
much today due to rain and extensive cloud cover.

.LONG TERM...(Monday through Saturday)
Issued at 358 AM CDT Sun Aug 19 2018

Monday looks to be a raw day with cooler temps, cloudy
skies and strong northwest winds. As the upper and surface lows move
to our east, a decent pressure gradient sets up over Neb and KS,
thus giving us the windy conditions. However, things should then
improve for Tuesday with shortwave ridging again in place.

For the rest of the workweek, it appears a gradual warm up is in
store for the region and we will be close to average highs for
this time of year by Friday. It should be dry for the most part
although several models continue to advertise a few disturbances
moving through between Tue night and Friday morning.


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Monday)
Issued at 624 AM CDT Sun Aug 19 2018

Widespread area of rain has moved into the terminals and expect
off and on chances for much of the forecast period. Both terminals
MVFR at the moment, but imagine they will bounce back and forth
between VFR/MVFR depending on when heavier bands of showers pass
through. Ceilings should lower some after midnight and its
possible they could end up IFR late tonight.




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