Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 230448

Area Forecast Discussion
National Weather Service Goodland KS
948 PM MST Wed Feb 22 2017

Issued at 946 PM MST Wed Feb 22 2017

Just completed an update. Main change was to insert patchy fog for
later tonight into mid morning tomorrow. Also increased cloud
cover during this time. Adjusted the high temperatures down a few
degrees for tomorrow. However, considering the current data,
temperatures, especially in the north could be way too warm.


.SHORT TERM...(This evening through Thursday)
Issued at 233 PM MST Wed Feb 22 2017

Trough over the Great Basin today will move east tonight and
emerge onto the central and northern high plains on Thursday. A
surface low will develop on the old front in southwest Kansas and
move north as a warm front Thursday afternoon. Temperatures along
and south of the warm front will reach the middle to upper 60s or
warmer, with brisk west to southwest winds. Dew points will tank
in that airmass and a red flag warning has been issued. Due to
uncertainty on how far north the front will get, a fire weather
watch has been issued up to I70. Precipitation will develop in the
afternoon north of the warm front. There is some weak instability
forecast near and just north of the front, only a few hundred
joules at best, and deep layer shear will be off the charts, but
with the limited instability not expecting anything severe,
however will mention isolated thunder. Might see rain changing to
snow Thursday afternoon in northeast Colorado in the colder air,
but little if any accumulation is anticipated.

.LONG TERM...(Thursday night through Wednesday)
Issued at 212 PM MST Wed Feb 22 2017

Main focus for this period will be the drastic change in temperature
and windy conditions Thursday night and Friday.

The main impact with this storm system will be the abrupt change
from spring-like temperatures to late winter temperatures.
Currently have lows falling to the 20s Thursday night and only
warming into the 30s Friday, which may still be too warm. In
addition wind gusts of 30-40 MPH will contribute to wind chills
falling into the single digits Thursday night and Friday morning.
The northwest winds will increase further on Friday, with gusts of
45 MPH, before becoming light Friday evening.

Thursday evening the cold front will move through the rest of the
Tri-State Area.  There is some difference regarding how quickly the
front will move through, which will determine how quickly the rain
will change to snow behind the front.

Looking at the previous model runs of the
NAM/GFS/ECMWF/Canadian/SREF shows a mixed message.  Some of the
models show a slightly faster cold front while others have shown no
change or a slower frontal speed.  Models do agree that the cold
front will be most if not completely through the Tri-State Area by
late evening.

Ahead of the front am not expecting any precipitation due to the
pronounced dry slot. Along/behind the front the environment
becomes saturated and mixing ratios increase for a brief time.
The mixing ratios show a narrow corridor of higher water content
behind the front before the drier air moves in. Soundings show a
similar trend of saturation with the frontal passage then gradual
drying through the night. However the environment continues to be
saturated due to the CAA. The lower mixing ratios coming in
indicate any snow that occurs will have a lower water content
through the night and into Friday.

The best chance for precipitation will be during the evening when
the best lift moves through behind the front.  Precipitation chances
will mainly be north of I-70 where the environment will saturate
behind the front, although cannot completely rule out some more
isolated chances to the south.  Chances for precipitation decline
after midnight and through Friday due to lift weakening as the storm
system moves further from the Tri-State Area.

Have lower confidence with the current precipitation chances after
Thursday evening due to the weakening lift that may be present over
the northern part of the forecast area behind the storm system.
Thought about removing the chances but cannot rule out the
possibility of snow lingering into Friday due to some models
keeping weak lift over the north part of the Tri-State Area during
this time. In addition the saturated layer will be in the
dendritic growth zone, so any amount of lift may lead to some
snowfall. With this in mind will leave the lower chances for
precipitation alone.

Snowfall amounts continue to be very low due to the fast moving
nature of the storm system and the low water content of the air.
SREF ensemble plumes continue to support less than two inches of
snowfall accumulation over the Southwest Nebraska counties where
the best chance for snowfall will be. The warm ground temperatures
will also hinder snowfall accumulation. While snowfall amounts
will likely change over the next couple days, confidence continues
to increase that snowfall accumulations will be around an inch or

Friday night into Saturday morning will be the coldest for the
week, with lows falling into the teens. Despite the light winds,
wind chills will fall into the single digits again.

After Friday temperatures will gradually warm, with the warmest
temperatures of the week expected Monday and Tuesday ahead of the
next cold front to move through on Tuesday.  There will be some low
chances for precipitation Tuesday as an upper level trough moves
across the Plains.  However the majority of the lift with this
trough currently will be south of the Tri-State Area.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 441 PM MST Wed Feb 22 2017

Complicated forecast, especially by later tonight, due to high
uncertainty as to the speed and position of an incoming stronger cold
front. A weaker cold front has already moved through and shifted
the winds to the east. For Kgld...vfr conditions are expected
through the period. Around 06z easterly winds will increase to
near 15 knots. Beginning near 15z the winds will increase and
start shifting through the afternoon. Sustained winds will be 15
to 20 knots with gusts to 23 to 28 knots as the winds change from
southeast to south to southwest then to the west to northwest late
in the afternoon.

For Kmck...until the 09z to 11z time frame, vfr conditions are
expected. At the above time, the easterly winds will increase to
near 15 knots with gusts to near 24 knots as mvfr ceilings
develop. Near 15z those winds will become a little more east
southeast at 20 knots gusting to near 28 knots as ifr ceilings
develop. Around 19z the winds shift to a more east northeast
direction as conditions become mvfr as light rain showers start
affecting the site.


KS...Red Flag Warning from 11 AM MST /noon CST/ to 6 PM MST /7 PM
     CST/ Thursday for KSZ027>029-041-042.

     Fire Weather Watch from Thursday morning through Thursday
     afternoon for KSZ013>016.

CO...Red Flag Warning from 11 AM to 6 PM MST Thursday for COZ254.

     Fire Weather Watch from Thursday morning through Thursday
     afternoon for COZ253.



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