Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 181708
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1108 AM CST Sun Feb 18 2018

...Aviation Update...

.UPDATE...
Issued at 1027 AM CST Sun Feb 18 2018

Issued Red Flag Warning for Phillips, Rooks, and Osborne counties
in Kansas. Dewpoints have been running a few degrees lower than
expected, and winds are starting to consistently gust to around 30
MPH (or more). The question that remains is how quickly winds
decrease this afternoon and evening.

Near-term grids have been adjusted to account for the lower
humidities today.

&&

.SHORT TERM...(Today and tonight)
Issued at 304 AM CST Sun Feb 18 2018

The weather will change from warm and windy today, to cold and
wintry tonight. An upper trough will dig into the Pacific Northwest
today allowing for even warmer air to spread northeast across the
Central Plains for a day, ahead of an approaching cold frontal
boundary. Temperatures have been warming during the pre-dawn hours
and will be mild to start the day, due to steady southerly low
level flow in a tightening pressure gradient as low pressure
deepened in the north central Rockies/front range. The strong
south winds will be noticeable with wind gusts over 40 mph at
times. The wind speeds will gradually subside from north to south
later this afternoon and evening as the surface trough/cold front
progresses south from northern Nebraska.

Temperatures still look on track to be warm and well above normal
ahead of the front, averaging in the 50s and 60s for highs as
cloud cover varies. Satellite imagery shows a swath of high level
clouds across the Dakotas into northern Nebraska associated with
the upper level jet. Models keep the brunt of these clouds north
of our area, but some filtered sunshine may impact our northern
zones. Also to the south, satellite is showing additional high
level clouds lifting north from the southern plains and as flow
aloft transitions more southwesterly today, these clouds may lead
to filtered sun for our southern zones. At this time, cloud cover
does not appear that it will have a significant impact on
temperatures.

The warm weather will be very shortlived as a cold front enters our
northern zones toward evening and reaches our far southeast zones
Monday morning. Sharply colder air advects south behind the
boundary, with some gusty north winds in the higher pressure rises
behind the front. Low level moisture increases tonight, leading
to the potential for freezing drizzle or drizzle depending on the
surface temperature, as moisture needed for the development for
ice crystals/snow is lacking. It doesn`t take much for freezing
drizzle to cause some problems and cannot rule out the potential
for light ice accumulations into Monday morning primarily for our
eastern zones. Have opted for a winter weather advisory for areas
east of a line from Fullerton to Clay Center where confidence is
higher for light icing, and the headline may need to be expanded.

.LONG TERM...(Monday through Saturday)
Issued at 304 AM CST Sun Feb 18 2018

The light freezing drizzle potential lingers into Monday morning in
our eastern zones, with the forecast drying out for the afternoon.
Temperatures will struggle in the cold air with little diurnal
range from lows Monday morning to highs during the day.

The western upper trough digs into the south central Rockies Monday
night with lift increasing again, bringing the potential for a
messy wintry mix of snow/sleet/freezing drizzle as a warm nose
aloft extends north into portions of central and eastern Nebraska.
This next round of precipitation should remain light with the
main snow band favoring northern Nebraska and greater ice
accumulations expected to our east. But again, similar to
tonight/Monday morning it does not take much freezing drizzle to
cause issues and will need to monitor for another potential
winter weather advisory headline.

The mid level shortwave crosses the plains Tuesday, finally pushing
the warm air aloft south and ending the freezing precipitation
potential. Light snow chances continue through the morning or early
afternoon in our northern zones with some light snow amounts of
half inch to an inch possible.

The coldest wind chills this upcoming week will be Monday
night/Tuesday morning and again Tuesday night/Wednesday morning with
readings of zero to 15 degrees below zero.

This round of cold air finally begins to dislodge Wednesday as the
upper trough departs. While not as cold Thursday-Saturday, the
pattern does remain active late this week and into next weekend
with intermittent chances for rain/snow.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Monday)
Issued at 1104 AM CST Sun Feb 18 2018

Strong south-southwesterly winds will continue into the
afternoon, before gradually becoming light and variable as a front
approaches in the late afternoon and early evening. Winds then
will shift northerly, gusting to around 25 kts overnight.

Expect stratus with at least low-end MVFR ceilings to develop
behind this front. Some patchy freezing drizzle may also develop
in the early morning Monday. Better chances are east of the
terminals, but I went ahead and mentioned it at KGRI.

&&

.FIRE WEATHER...
Issued at 304 AM CST Sun Feb 18 2018

Fire weather conditions remain a concern for the southern portions
of the forecast area today, primarily for locations south of a
line from Arapahoe, NE to Burr Oak, KS.  A tight pressure
gradient and deep mixing to H85 will lead to very windy
conditions and intense wind gusts today. Winds at the top of the
mixed layer average 33 to 40 kts and resultant wind speeds of 25
to 30 mph will be common with gusts over 40 mph at times. As
afternoon temperatures warm into the 60s to near 70 degrees in our
southern zones, relative humidity values will lower into the 20th
percentile across the majority of north central Kansas into far
southern Nebraska. Low level moisture is expected to nose north
through central Kansas in the strong southerly low level flow
during the afternoon, and should steady afternoon relative
humidity values, keeping RH values from falling to critical
thresholds below 20 percent.

With the steadying humidity in the afternoon, will maintain the near
critical fire weather conditions in the HWO and hold off on a Red
Flag warning. If this moisture axis is slower to arrive or mixing
is deeper than models currently suggest, an upgrade to a Red Flag
warning may be needed as winds will be very strong today.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory from 3 AM to 9 AM CST Monday for NEZ063-
     064-076-077.

     Winter Weather Advisory from midnight tonight to 9 AM CST Monday
     for NEZ041-048-049.

KS...Red Flag Warning until 7 PM CST this evening for KSZ005-017-018.

&&

$$

UPDATE...Mangels
SHORT TERM...Fay
LONG TERM...Fay
AVIATION...Mangels
FIRE WEATHER...Fay



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