Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 230916
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
216 AM MST Thu Feb 23 2017

.SHORT TERM...(Today through Saturday night)
Issued at 216 AM MST Thu Feb 23 2017

Across the Tri State region this morning...temps are ranging from
the mid 30s to the mid 40s as the area currently lies north of a
frontal boundary. The placement of this front...combined with high
pressure to our north and a surface low over southern Colorado is
giving the area a mixed sky cover. With clear skies currently over
western zones and mostly cloudy to cloudy conditions elsewhere as
stratus works south from Nebraska ahead of the surface ridge...and
mid/high cloud works across much of Kansas. There is also a general
ENE surface flow over the area ahead of the ridge.

For today on thru Friday night...it will be the surface low over
southern Colorado along with the frontal boundary draped over the
area...that will place the key roles for the wx over the region. The
low over Colorado is expected to shift eastward along the boundary
during the day today shifting east of the CWA late tonight into
Friday. As the low moves east the front will meander northward into
the CWA splitting the area along the I-70 corridor.

Temps are going to be warm enough initially for much of the CWA to
allow for rainshowers to develop. By the afternoon hrs with the low
over western Kansas...instability N and E of the low will trigger
some isolated t-storms. Best chances will occur over eastern zones
where SPC currently has portions of the east in Marginal Risk for
severe wx.

As the day progresses this afternoon...winds will begin to shift on
the backside of the low...allowing for colder air to infiltrate the
CWA...giving the area a change over to a rw/sw mix and eventually sw
as the evening hrs come about. Latest model guidance has increased
the amount of qpf for much of the northern CWA during this timeframe
and with decent CAA into the area...have increased snow totals.
Primary focus for accum will remain north of I-70 especially near
the KS/NE border where 1-2" is possible...down to 0.5" or less the
further south you go. Snow will taper off from west to east during
the day Friday before ending. By Friday night on thru Saturday night
high pressure returns over the area for dry conditions.

Other concerns for the Thursday to Friday night period will be Fire
Wx and strong winds.

First off...south of the frontal boundary thru the day...region will
remain mostly dry with lower RH readings versus northern locales.
Thinking the placement of the front will allow for the southern tier
to remain under Red Flag conditions so have continued warning...but
have dropped the Fire Weather Watch for the next tier of counties
along I-70. These areas may briefly hit criteria but not for the 3-
hr expected period for a warning.

Strong wind conditions will also ensue with the passage of this
system and across the CWA Friday on the backside of the exiting low.
Looking for gusts into the 30-40mph range with some locally higher
amounts near 45 mph possible.

Overall for temps...the CWA for today will see a north to south
orientation for highs and will be dependent on where the front sets
up...but upper 30s to near 40F up north to transition to low 60s
south is the best bet at this time. Cold air in place for Friday
with highs only in the upper 20s north to the mid 30s south...but by
Saturday...much of the CWA will trend upward into mostly the lower
to mid 40s. Overnight lows will mainly range in the teens to low 20s
at best. With these cold temps at night...and the expected
winds...wind chill readings could drop into the single numbers above
zero for Thursday/Friday nights.

.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
less.

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 06Z TAFS through 06Z Thursday night)
Issued at 1041 PM MST Wed Feb 22 2017

New guidance is now indicating that the front will be further
south than earlier guidance. Therefore worsening will start sooner
and also be further south than previous forecast. For Kgld...ifr
conditions are expected to develop near 12-13z and last until 16z.
At 16z conditions will become mvfr and continue through the rest
of the period. From 16z to 20z the southeast winds will be near 15
knots with gusts to near 23 knots. Those winds will shift to the
northeast at 20z and increase to 20 knots with gusts to 28 knots.
At 23z the winds will shift to the north at 20 knots with gusts to
30 knots.

For Kmck...From 09z to 15z ifr conditions and east winds of 18
knots with gusts to 25 knots are expected at the site. From 15z to
21z mvfr conditions and east winds of near 20 knots with gusts
approaching 30 knots are expected. From 21z through the end of
period ifr conditions north to northeast winds of near 20 knots
with gusts to near 30 knots can be expected.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from 11 AM MST /noon CST/ this morning to 6 PM
     MST /7 PM CST/ this evening for KSZ027>029-041-042.

CO...Red Flag Warning from 11 AM this morning to 6 PM MST this
     evening for COZ254.

NE...NONE.
&&

$$

SHORT TERM...JN
LONG TERM...JTL
AVIATION...BULLER



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