Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 220520

Area Forecast Discussion
National Weather Service Goodland KS
1120 PM MDT Wed Mar 21 2018

.SHORT TERM...(This evening through Saturday)
Issued at 130 PM MDT Wed Mar 21 2018

Tonight-Thursday night...the forecast area will be under the
influence of an upper level ridge with only some mid and/or high
clouds spilling over its axis and across the area. Low temperatures
tonight in the upper 20s to mid 30s. On Thursday 850mb temperatures
warm about 7F to 10F supporting highs in the low to mid 70s. Clouds
increase Thursday night with lows in the low to mid 40s.

Friday...west to northwest winds gradually increase from west to
east during the morning ahead of a cold front that moves through
during the early to mid afternoon. Peak winds should reach the 30 to
35 mph range during the day. Showers and a few thunderstorms are
possible generally along and north of the interstate during the
afternoon and evening hours with dry weather expected after
midnight. A little less certain on high temperature forecast given
timing issues with the frontal passage. Right now have readings
ranging from the low 70s north to low 80s far south. Low
temperatures range from the low/mid 30s in far eastern Colorado to
the upper 30s to low 40s east of the CO/KS border.

Saturday...dry weather expected. The upper level ridge axis
redevelops with some high clouds from time to time. Afternoon
temperatures cool back into the low 60s to around 70. Southeast
winds increase into the 20 mph range with higher gusts in the
afternoon generally along and west of the CO/KS border.

.LONG TERM...(Saturday night through Wednesday)
Issued at 220 PM MDT Wed Mar 21 2018

Main forecast concerns will be active weather pattern from Sunday
through the end of the period and possible fire weather issues on
Sunday. Satellite is showing an amplified pattern from the Pacific
into eastern North America. This flow is slightly amplified from
yesterday at this time.

Deterministic models have come into much better agreement on the
flow and evolving incoming trough. The models are now all
developing a closed low over the Great Basin/Intermountain west
and then sinking that low south toward U.S./Mexican border in the
desert southwest. This leaves the area in a southwest flow aloft
with shortwave troughs moving through during this time.

Ensemble output supports this general idea so confidence is higher
in this outcome. The differences that exist now is how fast to
develop the low and how far south it will move. The Canadian is
slightly different in that it develops the low slower and
initially further north before sinking it south in a similar
fashion to the 12z Gfs and 00z Ecmwf.

The 12z Gfs and 00Z Ecmwf developed the slow sooner and further
southwest than the Canadian. By the end of the period the 00z Ecmwf
and 12z Canadian sink the low a little further south and west than
the Gfs. The 12z Ecmwf is generally doing the same as the previous
run. However, it is now developing the low a little slower and
further west and north from its earlier run and the 12z Gfs.

Considering that the flow is looking more split, it is a common bias
of the output to not take the southern and northern branches far
enough south. If that happens in this situation, the better moisture
and lift end up further south as we get caught in the flat and
progressive flow. This might not be a problem since shortwave
troughs in the south to southwest flow aloft along with periodic
help from the jet could affect the area and bring periodic episodes
of precipitation. Definitely something to watch closely.

Comparing this to what the forecast builder gave me, its output
looks reasonable. Forecast builder puts in regular occurrences of
precipitation through the period. At this time, the Gfs is showing
some surface based and elevated Cape for most of the period from
Sunday night into Monday evening. So inserted a chance of
thunderstorms in there. Although details, per reasoning given above,
and subtle changes in the frontal and upper low position will
probably mean adjustments will be needed in the phase and areal
coverage of the precipitation.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1115 PM MDT Wed Mar 21 2018

VFR expected at both KGLD and KMCK as an upper level ridge
results in partly cloudy skies and light winds.


Issued at 130 PM MDT Wed Mar 21 2018

A Fire Weather Watch has been issued for Friday. Areas include
those generally along and west of a line from Burlington to Leoti.
In these areas west to northwest winds of 15 to 25 mph with higher
gusts will combine with relative humidity near 15 percent to
create critical fire weather conditions.

Near critical fire weather conditions are possible Saturday for
the western half of Cheyenne and Kit Carson counties of Colorado.
In these areas relative humidity approaching 15 percent will
combine with southeast winds gusting 25 to 30 mph.

For Sunday...Elevated fire weather conditions are still expected
over the far south and southwest portion of the area, roughly along
and west of a line from Tribune to Cheyenne Wells to Bethune.
Relative humidities will be in the 10 to 15 percent range. Winds are
the marginal portion of this and do not look like they will reach
criteria. Definitely a period to keep watching.


KS...Fire Weather Watch Friday afternoon for KSZ027-041-042.

CO...Fire Weather Watch Friday afternoon for COZ253-254.



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