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FXUS63 KGID 172315

Area Forecast Discussion
National Weather Service Hastings NE
515 PM CST Sun Dec 17 2017

.SHORT TERM...(This evening through Monday)
Issued at 219 PM CST Sun Dec 17 2017

After a cooler day today, warmer weather will return for the start 
of the workweek. It was an interesting day with light precipitation
in our southeast zones this morning, with a hole in the cloud 
cover across much of our cwa with clear skies, while our far east 
and western zones were impacted by low clouds. Short term models 
are in good agreement that the low cloud cover will scatter/erode 
by evening and with decreasing cloud cover tonight, temps should 
drop to the teens/20s for lows. Temperatures rebound nicely on 
Monday in rising heights and warm air advection. Sunshine, 
downslope winds and airmass change of 7C at H8 will lead to a much
warmer day with highs in the 50s.

.LONG TERM...(Monday night through Sunday)
Issued at 219 PM CST Sun Dec 17 2017

Dry weather with above normal temperatures will persist through 
Wednesday, then the weather pattern undergoes changes to colder 
conditions Thursday through the remainder of the outer periods.

A weak cold frontal passage Monday night will allow for some 
negligible cooling on Tuesday, only a few degrees shy of Monday's 
high temperatures.

The pattern aloft Wednesday is fairly zonal across the plains ahead 
of an upstream trough in the northwest CONUS. Southerly low level 
flow increases during the day, however models have slowed the 
progression of the approaching trough and Wednesday is not looking 
quite as windy as it did 24 hours ago.

With the slower timing of the western trough, the forecast for 
Thursday is also changing. The cold front which was supposed to 
cross our region Wednesday night (as indicated 24 hours ago) now 
looks to move through Thursday morning, with the brunt of the cold 
air arriving Thursday afternoon or night depending on the model 
(ECMWF faster than GFS). Due to the slower timing of the front, 
temperatures Thursday have increased, however depending on the 
timing, readings may steady or fall during the afternoon. 
Precipitation chances are not looking overly promising either, as 
the ECMWF gives us a glancing chance for rain/snow with fropa, then 
focuses the better snow chances to our north. The GFS on the other 
hand, still suggests the potential for light snow accumulations with 
its deeper and slower mid level trough progression across the plains 
and holds onto snow potential into Friday.

While precipitation chances and snowfall are looking a little more 
iffy, confidence on the pattern change and arrival of cold air is 
high. Reinforcing shots of cold air will arrival through the weekend 
with temperatures struggling to reach the 20s for highs Saturday and 
Sunday (Christmas Eve) while lows will be frigid in the single 
digits. The current forecast also carries light snow chances into 
the weekend time frame, however confidence is not high given the 
changes we have seen already for Thursday. 


.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 501 PM CST Sun Dec 17 2017

Weak mid level wave approaching central Neb and this should move 
through this evening. Expecting a few more hours of MVFR before 
clouds thin out/pass through the terminal areas as wave progresses
to the east. Clouds should not be an issue overnight into Monday 
with VFR conditions expected. Light winds will gradually pick up 
late tonight into tomorrow out of the southwest as primary surface
low passes well to the north. 




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