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FXUS63 KGID 222359

Area Forecast Discussion
National Weather Service Hastings NE
659 PM CDT Thu Jun 22 2017

.SHORT TERM...(This evening through Friday)
Issued at 317 PM CDT Thu Jun 22 2017

The main focus in the short term is the chance for thunderstorms and 
the potential for a strong/severe storm this evening. 

Flow aloft across the Central Plains was fairly zonal with a high 
pressure ridge in the desert southwest, tropical depression Cindy 
along the TX/LA border and an upper low in Manitoba. At the surface, 
a cold front was advancing southeast across central Nebraska and 
western Kansas early this afternoon. The cold front combined with a 
lead shortwave trough translating southeast across the plains around 
the northern upper low will provide the focus for shower and 
thunderstorm development into the evening. 

By late afternoon, the front will be oriented across the southeast 
third of our cwa and models are in decent agreement with development 
initiating across north central Kansas and potentially filling in to 
the northeast into Nebraska along the baroclinic zone. There is a 
few hour time frame where strong to severe storms may occur with 
instability near 3kj/kg along the boundary with shear in the 20 to 
30kt range and storms will be capable of producing large hail, 
damaging winds as well as locally heavy rainfall with 
precipitable water values averaging an inch and a half. 

The cold front moves out of our cwa during the evening with 
instability decreasing north/south and a period of dry weather is 
expected before precipitation chances increase again overnight or 
early Friday as convection which develops along the high plains 
works eastward before dissipating by midday Friday. 

The big news for Friday is the pattern change we see behind this 
system/cold front. We tap into a cooler Canadian airmass behind this 
front with the pattern transitioning to northwest flow for our 
region as an upper trough deepens across the plains and Ohio 
valley region. Mid level temps which were near 30C during our heat
spell earlier this week drop a solid 15C or more by Friday and 
temperatures will be noticeably cooler with highs in the low/mid 
70s. Conditions will also be less humid as dewpoints drop into the
40s. Friday will also see breezy/windy conditions as model 
forecast soundings indicate mixing above H85 and winds at the top
of the layer average 25 to 30kts.

.LONG TERM...(Friday night through Thursday)
Issued at 317 PM CDT Thu Jun 22 2017

After what looks to be a rather breezy day on Friday, winds should 
begin to diminish as we head into the evening hours. Any lingering 
light showers will have since dissipated or moved out of the area 
and things should remain dry overnight. 

The seasonably cool temperatures will continue into the weekend as 
the upper level trough sinks a bit further south into the central 
plains helping to sustain this period of below normal temperatures. 
Overall am expecting highs in the 70s Saturday and Sunday with winds 
generally out of the north and west. A few scattered rain showers 
are possible along a semi-stationary boundary in our southwestern 
zones as a weak wave drifts around the southern end of the trough. 
Overall am not expecting much in the way of widespread 
precipitation. With the cooler temps and limited to no CAPE in the 
area, have not included any mention of thunder through Sunday.

As we move into the beginning of the work week, the ridge that has 
dominated the southwestern CONUS this past week quickly builds back 
north and east into the plains. Southerly flow returns ushering in 
more seasonable temps with highs in the 80s and low 90s by Thursday. 
Another trough from the northwest gradually shifts eastward 
supporting an increase in precipitation chances as a series of 
shortwaves push off the Rockies. This will bring periodic chances 
for thunderstorms Monday through Wednesday.


.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 656 PM CDT Thu Jun 22 2017

VFR Conditions expected as wind eventually laxes a bit this
evening behind a cold front passage.




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