Area Forecast Discussion
Issued by NWS Hastings, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGID 240550
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1150 PM CST Fri Feb 23 2018

.SHORT TERM...(This evening through Saturday night)
Issued at 328 PM CST Fri Feb 23 2018

The main concern in the short term is the impending winter storm.
The details are tricky and have evolved and will continue to
evolve into the event.

The main points:
1. Overall have lowered snowfall totals across the area, generally
2-4 inches of snow expected along and north of the I-80 corridor.
Elsewhere a trace to 2 inches possible.

2. Icing is still a concern, but a big question is where a
transition line for ice vs. snow will set up. Still have ice
accumulations up to a tenth or slightly higher, but question this
some with drizzle expected. Regardless, any amount of ice on
roadways can cause very difficult travel conditions.

Overview:
An open wave is moving northeastward across the Central Plains
bringing a low pressure system to the region. This system will
bring snow and ice beginning tonight persisting through the day on
Saturday.

Details:
Timing:
Precipitation is expected to being during the overnight hours,
sometime between 1 and 3am moving into the area from northwest
Kansas. The heaviest snow and snow accumulations will be during
the morning hours and the storm is expected to exit to the east
during the late afternoon/evening.

Precipitation type:
The forecast is tricky, mainly in figuring out precipitation type.
Looking at soundings across south central Nebraska and north
central Kansas, the question is regarding the presence of ice
aloft. Saturation is below the -10C layer and thus think Drizzle
will be the main precipitation type for areas along and south of
I-80 at the onset of precipitation. Along and north of I-80 ice
in the column allowing for snow to be the main precipitation type
through the whole event. This would include places like Ord,
Lexington, Kearney and Grand Island. As the system moves overhead,
the column is expected to saturate from west to east changing
freezing drizzle to snow.

Now depending on how the column actually saturates and where the
ice is present will impact who will see snow vs. freezing drizzle.
If more snow than freezing drizzle falls, snow totals could be
increased slightly, and vice versa...more freezing drizzle than
snow would reduce snowfall totals.

Accumulations:
Snow:
As stated earlier, have lowered snowfall accumulations across the
area and the latest guidance indicates that the heavier bands may
be even further west in the Sandhills with a general 1-2 inches
across most places in south central Nebraska. North central Kansas
will see light accumulations, but nothing more than an inch.

Ice:
Ice accumulations are between a trace to a 0.15" generally across
north central Kansas and areas along and south of I-80 in
Nebraska. This may be high if drizzle indeed remains the main
precipitation type, if freezing rain does develop (more ice in
the column), then those values may be closer to reality.

Uncertainty:
Due to the uncertainty of where the line of drizzle/snow may set
up and the trend downward for snow, the forecast will change.
Please stay aware of the latest forecast updates.

.LONG TERM...(Sunday through Friday)
Issued at 328 PM CST Fri Feb 23 2018

Dry conditions remain in the forecast for the latter half of the
weekend. Models are in good agreement showing zonal flow in place
aloft at 12Z Sunday, with another shortwave disturbance sliding
through CO. At the surface, the day starts out with westerly winds,
with the CWA sitting between low pressure over the Great Lakes and
high pressure over the Southern Plains. Through the daytime hours on
Sunday, this upper level shortwave disturbance slides east through
the region, but with a lack of moisture to work with, it`s a dry
passage. Westerly winds remain in place through the day, and with
more sun expected, should have warmer temperatures compared to Sat,
and forecast highs are in the 30s/40s.

The warming trend is expected to continue into Monday/Tuesday, as
are the dry conditions. Models show zonal flow continuing through
Monday in the wake of the disturbance passing on Sunday, before
turning more southwesterly on Tuesday in response to a low pressure
system digging south along the West Coast. Winds on Monday turn more
southwesterly and look to be on the gusty side, as the surface high
shifts east and low pressure extends from the Dakotas down into
eastern CO. Models are in good agreement showing a warmer air mass
advecting north into the region, and along with favorable wind flow
and mostly clear skies...forecast highs are well into the 40s in the
north, with 50s south. Near 60 not out of the question in north
central KS. Will have to keep an eye on fire weather potential,
mainly across our KS counties, where some afternoon RH values are
right around 20%. While the daytime hours on Tuesday remain dry, a
surface front looks to be working its way south into the CWA,
affecting temperatures. May end up with a tight gradient, current
forecast highs range for the upper 30s north to mid 50s south.

Late Tuesday night through Wednesday night brings the next chance
for precipitation, but not a lot of confidence due to plenty of
model differences. The system starting the week out over the western
CONUS shifts east, but main question is whether it`s a more
organized stronger closed system like the GFS shows, or an weaker
open wave like the ECMWF. Preciptiation type at this point looks to
be a mix of rain/snow, forecast highs Wed drop back into the
30s/40s.

The forecast for the ends of the work week dries back out, temps
gradually warm.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Saturday)
Issued at 1143 PM CST Fri Feb 23 2018

We continue to expect a winter storm system to impact our area
especially through the first half of the day with improving
conditions during the afternoon. Forecast models keep indicating
less precipitation with each new update and snowfall amounts may
need further reductions with 1 to 3 inches now looking like the
best bet for KEAR and KGRI with current odds leaning towards the
lower end of that forecast range. In addition, freezing drizzle,
which previously was primarily a threat southeast of our TAF sites
may now be a problem at KEAR and KGRI at least initially around
dawn before precipitation turns over to snow. Therefore, have
added freezing drizzle to the TAF with the 06Z issuance. In
addition, ceilings will be IFR and maybe even LIFR throughout the
morning hours before seeing some improvement this afternoon.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 6 PM CST Saturday for NEZ039>041-
     046>049-060>064-072>077-082>087.

KS...Winter Weather Advisory until 6 PM CST Saturday for KSZ005>007-
     017>019.

&&

$$

SHORT TERM...Billings Wright
LONG TERM...ADP
AVIATION...Wesely



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.