Area Forecast Discussion
Issued by NWS Goodland, KS

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268
FXUS63 KGLD 192026
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
126 PM MST Sun Feb 19 2017

.SHORT TERM...(This evening through Monday)
Issued at 126 PM MST Sun Feb 19 2017

Latest upper air analysis shows a trough over the Desert Southwest
extending into Mexico.  To the east a ridge was located over the
Mississippi River Valley.  Ahead of the trough water vapor was being
channeled north over the Plains.  Accompanying the trough was much
drier air.

This evening have low confidence for any rainfall development.  As
the upper level trough approaches the Tri-State Area lift increases,
but drier air also moves in.  The only chance for rainfall currently
looks to be over the eastern part of the forecast area where weak
lift will be coupled with increasing moisture ahead of the
encroaching dry air.  Any storms that develop will shift east before
midnight.  Meanwhile over to the northwest a band of elevated
moisture does move across Yuma and neighboring counties, but it is
not very deep. Am not expecting any precipitation from that as a
result.

The breezy winds will continue well into the evening due to the
tight pressure gradient ahead of a pre-frontal trough that will move
through overnight.  As the trough moves through south winds will
decline and turn to the northwest.  The northwest winds will
gradually increase as the pressure gradient tightens behind the
trough.  A weak cold front will accompany the increasing winds
overnight.  Behind the front dew points will lower as drier air
moves in.

Lows will be cooler than last night in East Central Colorado due to
the cold front and drier air.  To the east lows will be the same to
a few degrees warmer.  The lows over the east continue to be similar
to what normal highs for this time of year would be.  The very warm
lows from last night and tonight may well set/tie records for the
warmest low for today.

Monday northwest winds will increase in the morning, with winds
reaching a peak around noon.  During the afternoon winds will
gradually decline as the low level jet overhead weakens.  Highs will
be cooler than today, despite the clear sky, due to the cooler air
mass.  The breezy winds and dry air may lead to critical fire
weather conditions.  See fire weather section for further
information.

.LONG TERM...(Wednesday through Saturday)
Issued at 154 AM MST Sun Feb 19 2017

Primary concern in the extended periods is the potential for a
winter storm to develop in the Thursday through Friday timeframe.

Wednesday: Surface trough shifts southeast, and main axis of WAA
should follow, however temps aloft remain very warm. Considering
biases and current trends we may see similar highs in our south and
east as on Tuesday with near daily records once again. Elevated fire
weather conditions are possible due to lower RH, however surface
gradient and winds aloft should be weak enough that winds should not
be an issue.

Thursday-Friday: Majority of guidance (discounting GEM) has trended
further south placing our CWA in a better position for precipitation
and a possible winter storm. There is significant disagreement on
mid level evolution even with favorable models, which impacts how
this event evolves and possible amounts. Strong cold front should
move through our CWA by late Thursday afternoon or Thursday
evening, possibly sped up by evaporative cooling under main axis
of precip as it spreads east. Based on wet bulb profiles on
GFS/ECMWF we may have a quicker transition to snow than currently
indicated (basically as precip begins rather than a delay). This
adds another layer of uncertainty to possible snow amounts and
timing of impacts.

Strongest winds will tend to be immediately behind the front
Thursday evening, however latest ECMWF could support a longer
duration of strong winds correlated with snow raising the potential
for blizzard conditions.

Regarding amounts: Even with a delayed start to snow accumulations
to the late evening period, lower end of blends would support snow
accumulations approaching advisory criteria (3") and a possible
period of blowing snow. The strongest solution (currently ECMWF)
shows a deformation zone forming and tracking across our north, and
this is associated with warning criteria amounts (6+). While GFS is
weaker on forcing and pattern is more questionable on duration of
better accumulations, adjusting for a faster transition could result
in 3-6" amounts in our north. Ground temperatures are warm, and
lower rates may struggle to overcome this initially negatively
impacting amounts. However this would have little impact if rates
are as high as whats possible, and by late Thursday night colder
air will begin to take its toll on warmer surfaces.

Confidence is increasing we will see winter weather impacts
(particularly north of I-70), however I have low confidence on how
this will unfold and what the magnitude of these impacts will be.

Saturday: Pattern should be dry with west-southwest flow developing.
This would also support lee trough development and WAA, however
colder air mass may be slower to transition east and lingering snow
pack could play a role in complicating high temps.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1034 AM MST Sun Feb 19 2017

VFR to possibly IFR conditions forecast for the TAFs. Breezy winds
this afternoon will continue well into the evening. A pre-frontal
trough moving through will cause winds to turn to the northwest
overnight. As the winds turn they will decline. Behind the trough
northwest winds will increase Monday morning as a weak cold front
moves through. There may be some low level wind shear late this
evening as a strong low level jet develops ahead of the pre-
frontal trough.

KMCK may have some IFR clouds move through prior to winds turning
to the west tonight. The window of opportunity is short and models
disagree how moist the first few hundred feet will be.


&&

.FIRE WEATHER...
Issued at 126 PM MST Sun Feb 19 2017

Monday northwest winds will reach their peak around noon then
gradually decline, becoming light by the evening.  With dew points
falling in the afternoon, relative humidity will also fall with
values close to 10 percent.  Due to the wind speeds declining
through the afternoon as the relative humidity also falls, do not
have enough confidence that critical fire weather conditions will be
met for the required 3 hours.  However do have enough confidence to
issue a watch for the counties most likely to reach criteria.  Kit
Carson and Cheyenne counties in Colorado have the best chance at
meeting criteria.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Fire Weather Watch from Monday morning through Monday afternoon
     for KSZ001-013-027-041-042.

CO...Fire Weather Watch from Monday morning through Monday afternoon
     for COZ252>254.

NE...NONE.
&&

$$

SHORT TERM...JTL
LONG TERM...DR
AVIATION...JTL
FIRE WEATHER...JTL



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