Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 220545
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1145 PM CST Tue Feb 21 2017

.SHORT TERM...(Tonight through Wednesday evening)
Issued at 1145 PM CST Tue Feb 21 2017

This is an initial draft...

Aloft: Aircraft and 00Z soundings showed the Westerlies were
fairly zonal across the CONUS. A 120 kt jet streak extended from
CA-WY with multiple low-amplitude shortwave trofs on the N side of
it. A more substantial trof was approaching the W coast. The flow
overhead will become more anticyclonic tonight as this trof moves
inland today and progresses further inland tonight. A 700 mb low
will form after midnight and will be over S-cntrl WY by 12Z/Thu.

Surface: Low pres was along the SD-MN border with a cool front
extending across the Sandhills int CO/UT/NV. As the low conts
moving E...the cool front will pass thru the fcst area this
morning. It will become stationary from W-E across cntrl KS as lee
cyclogenesis occurs over CO.

More on sensible wx later...


.LONG TERM...(Wednesday night through Tuesday)
Issued at 201 PM CST Tue Feb 21 2017

Winter Storm System Thursday through Friday...
The big story will be a strong late winter storm system that will
track east out of the Rockies and strengthen over the plains
bringing much colder air and snow to the region. The best bet at
heavy snow accumulations will be across northern Nebraska where a
winter storm watch will be in effect. The heavy snow band is
currently expected to be north of our forecast area, yet our
northern zones, especially north of I-80, may still see a few
inches of wind driven snow primarily Thursday night into Friday.
We are right on the edge of this system and any slight shift of
the storm track could really influence expected snowfall amounts.

Most areas will only see a chance of rain during the day on
Thursday as the colder air continues to filter in on gusty
northerly winds. The best chance for rain will be Thursday
afternoon. However, by late afternoon northwestern zones from Ord
to Lexington could possibly begin to see the change over to snow
with that change over from rain to snow spreading southeast across
the area Thursday night. Most of any remaining wrap around
precipitation on Friday would be light snow for Nebraska...with
rain or snow if anything across northern Kansas. There are still
plenty of model differences in timing and storm track such as the
12Z and 18Z NAM is rather fast and brings more snow into our
northern zones Thursday afternoon but has all of the snow out of
here by Friday morning. The 12Z GFS and ECMWF are both slower
than the NAM with light snow primarily across Nebraska zones
through much of the day on Friday. The 12Z ECMWF is the
furtherest south model and does give Kansas zones at least some
chance of a few snow flakes although not much more than that.

Initially snowfall amounts currently look like little to nothing
over north central Kansas, a dusting up to maybe an inch or two
south of I-80, and then 1 to 5 inches north of I-80 with perhaps a
tight snowfall gradient. This is still very early and expect
forecast amounts to change as forecast models settle in on a
preferred storm track. Highs on Friday will only be around the
freezing mark across south central Nebraska to the upper 30s over
northern Kansas, a big change from the recent warmth. The north
winds Thursday into Friday should be gusty as the sfc low
strengthens over Kansas increasing the pressure gradient. Expect
wind speeds of 20 to 25 mph with gusts to over 30 mph at times.
These winds will make for blowing and drifting snow with poor
visibilities Thursday night into Friday across northern zones
where we see more snow.

Saturday through Tuesday...
Expect a gradual warmup with highs back into the upper 40s and
50s by early next week. Precipitation chances are not very good
from this weekend into early next week with just some small
chances Saturday night and again on Tuesday, but have little
confidence in these chances.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Thursday)
Issued at 1145 PM CST Tue Feb 21 2017

Significant Wx: LLWS until 14Z. WSHFT 12Z-15Z.

Rest of tonight: VFR with FEW-SCT cirrostratus around 25K ft.
Light SW winds 10 kts or less. LLWS. Confidence: High

Wed: VFR with FEW-SCT cirrostratus around 25K ft. Passage of a
cool front will shift winds to NW 11-15 kts. LLWS ends 14Z.
Confidence: High

Wed Eve: VFR CIGs invade around 10K ft 03Z-06Z. Winds shift to N
then NE under 10 kts. Confidence: High

&&

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

$$

SHORT TERM...Kelley
LONG TERM...Wesely
AVIATION...Kelley



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