Area Forecast Discussion
Issued by NWS Goodland, KS

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000
FXUS63 KGLD 171608
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1008 AM MDT Tue Apr 17 2018

.UPDATE...
Issued at 949 AM MDT Tue Apr 17 2018

Based on latest data have upgraded the high wind watch to a
warning and extended the high wind warning to last until 9z or 3
AM MT. No change to the red flag warning.

Latest data shows high winds moving both this afternoon behind the
warm front and later on behind the cold front that will enter the
forecast area early this evening. During the afternoon the high
winds will be most favorable west of Highway 25 as a very strong
low level jet follows the warm front east into the forecast area
and mixes to the ground. This evening a cold front will move in
from the west. As the cold front moves through a mixed layer will
form, allowing the very strong low level jet behind the cold front
to mix to the ground. Meanwhile the base of the upper level
trough will be over the forecast area this evening, shifting east
of the forecast area after midnight. The subsidence from the base
of the trough over the forecast area this evening will help to
further channel the winds to the ground.

Due to the base of the trough not shifting east of the forecast
area until after midnight, have extended the high wind warning
past midnight. For simplicity have the entire high wind warning
lasting past midnight. During the evening the threat for high
winds will shift east out of East Central Colorado. Will let the
next shift trim the high wind warning as needed.

There is still a threat for blowing dust with these high winds.
Not sure how much of a role the recent snow will have in regard to
keeping the ground damp enough to inhibit blowing dust. Since
there was a good deal of ground blown clean during the blizzard,
that ground is likely dry by now. Am thinking the snow will have
helped alleviate some of the threat for blowing dust, but not
completely removed it. Due to high winds expected to last into the
night, also believe the blowing dust threat will last into the
night.

The red flag warning is in good shape based on latest data. There
was some concern that the red flag warning may need to be extended
further east. However relative humidity values begin to increase
as the drier air moves east past the red flag warning area.
Despite some counties not being in the red flag warning, the lower
relative humidity values of 20-30% and high winds will lead to
dangerous fire weather conditions this evening.

&&

.SHORT TERM...(Today through Thursday)
Issued at 400 AM MDT Tue Apr 17 2018

A warm front will lift out of Colorado this morning as a surface
low deepens near Cheyenne, Wyoming, in response to a negatively
tilted shortwave trough moving out of the central Rockies.
Southwest winds will rapidly increase in the warm sector, with
gusts up to 60 mph. In conjunction with the gusty winds, relative
humidity will drop to less than 10 percent and SPC has highlighted
the area generally south of I70 as extremely critical for fire
weather, meaning explosive fire growth will be possible, while
areas just to the north and east of the extreme area will see
critical fire weather conditions. Finally, areas of blowing dust
may develop as well, with the usual threats of reduced visibility
and hazardous travel along the interstate and highways. A cold
front will move through during the late afternoon to early evening
hours, with winds shifting to northwest and continued gusty,
diminishing by late in the evening. Areas to the east may
experience a brief period of gusty winds with the cold front this
evening, so left a High Wind Watch intact there, with all other
areas upgraded to warnings for wind and fire weather. High
temperatures will top out in the low to mid 80s in the warm
sector, with 70s elsewhere.

Shortwave ridge will build over the area for Wednesday. Elevated
fire weather conditions are anticipated due to gusty northwest
winds and relative humidity as low as 20 percent. Do not think
there will be any critical areas. Otherwise, it will be mostly
sunny and cooler with high temperatures in the upper 50s to lower
60s.

Next system will dig into the Four Corners region on Thursday and
become a cut off low. Gusty southeast winds will develop by the
afternoon between high pressure to the east and falling pressures
in the Rockies. High temperatures will be in the middle to upper
60s. Will see low chances for rain showers developing late
Thursday night with weak impulses embedded in the southwest flow
ahead of the main low which will slowly approach the southern
Rockies.

.LONG TERM...(Friday through Monday)
Issued at 302 AM MDT Tue Apr 17 2018

Main concern is the storm system to affect the area at the end of
the week as active pattern continues. Satellite continuing to show a
highly amplified pattern from the Pacific into the western Atlantic.

Overall confidence has lowered from yesterday due to model
disagreement and trends shown by a few of those models. Models
start out in good agreement. However they start diverging with the
newest Ecmwf changing from its 12z fun. The problem is coming up
through Friday night when the models differ on how they want to
evolve this trough. Jet progs show that at the beginning of this
period that the strongest jet winds are at the bottom or the front
side of the system.

The Gfs has remained consistent from its previous run. It takes the
low from along the Utah/Arizona border/4 corners area straight east
until it pulls the system south into northeast New Mexico late
Friday night into early Saturday. It then progresses the system
nearly straight east the rest of the period.

The 12z Ecmwf basically did what the Gfs does except it was
slightly further south and slower. Now the 00z Ecmwf is mirroring
the Canadian, albeit a little faster/further north, by slowing up
the system and digging the system down into central/south central
New Mexico by 12z Saturday. Once the Canadian/Ecmwf do that they
take the system straight east. The WPC depiction goes more in the
middle and is closer to the operational Gfs and the GEFS mean. The
more southern solutions will definitely keep the best chance of
precipitation and the highest amounts further south.

The forecaster builder/blend reflected this trend further south and
has lowered the expected precipitation amounts from yesterdays
forecast. Many locations are still forecast to receive more than an
inch, but of course this could change if this further south trend
continues. All in all, I found what the forecaster builder gave me
was reasonable and did not pops/qpf or any other parameter from
Friday into Saturday night. Also this precipitation event looks to
be nearly all rain. The snow amounts are much less than yesterday
and considering the scenario that looks reasonable as well. At
this time the far western portion of my area looks to receive a
dusting of snow.

For Sunday into Monday, models start diverging even more. However
overall the ridging behind exiting system will lead to dry and
warmer conditions. As a result left the forecaster builder output
alone.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 516 AM MDT Tue Apr 17 2018

At KGLD...surface winds will increase from the southwest behind a
warm front around 19z with gusts up to 50kts possible. Another
wind shift will occur around 00z to the northwest behind a cold
front with gusts continuing. May see a period of reduced
visibility in blowing dust with the cold front from late afternoon
through early evening.

At KMCK...winds will be out of the southeast as the warm front
appears that it will not make it as far north as McCook. However,
the cold front will arrive around 00z-01z with surface winds
shifting to the northwest and increasing. Gusty northwest winds
will continue through Tuesday night.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...High Wind Warning until 3 AM MDT /4 AM CDT/ Wednesday for KSZ001-
     002-013-014-027-028-041-042.

     Red Flag Warning until 8 PM MDT /9 PM CDT/ this evening for
     KSZ001-002-013-014-027>029-041-042.

     High Wind Warning from 7 PM this evening to 4 AM CDT Wednesday
     for KSZ003-004-015-016-029.

CO...High Wind Warning until 3 AM MDT Wednesday for COZ090>092.

     Red Flag Warning until 8 PM MDT this evening for COZ252>254.

NE...High Wind Warning until 3 AM MDT /4 AM CDT/ Wednesday for NEZ079-
     080.

     Red Flag Warning until 8 PM MDT /9 PM CDT/ this evening for
     NEZ079-080.

     High Wind Warning from 7 PM this evening to 4 AM CDT Wednesday
     for NEZ081.

&&

$$

UPDATE...JTL
SHORT TERM...ERRYK
LONG TERM...BULLER
AVIATION...ERRYK



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