Area Forecast Discussion
Issued by NWS Goodland, KS

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547
FXUS63 KGLD 300526
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1126 PM MDT Sat Apr 29 2017

.SHORT TERM...(This evening through Sunday)
Issued at 255 PM MDT Sat Apr 29 2017

Main focus has been the current winter storm. Complexities of this
storm continue to increase as the brunt of the event nears.

Latest upper level analysis shows a closed low over New Mexico.
Ahead of the closed low water vapor analysis shows higher water
vapor being circulated over the High Plains. Latest radar shows
the next round of snow, currently over Southwest Kansas, gradually
moving northward. This will be the first round of snow for the
second half of this storm system.

Tonight conditions will degrade as the next wave of snow moves
north and stalls near the KS/CO border this evening. Accompanying
the band of snow will be a band of frontogenesis and very strong
lift in the dendritic layer. These two features lined up well with
the snow earlier today. This first band will fade as
frontogenesis/lift end around midnight. Overnight the main snow
event will begin as another band of frontogenesis develops along
with deep, strong lift. There is still some uncertainty regarding
where the band of frontogenesis will setup. Models have trended
this band further west. Have highest confidence the band will be
somewhere between the CO border and Highway 83. Along with the
heavier snow band, a broad band of moderate to heavy snowfall will
develop in the area of isentropic lift east of Highway 27. With
negative theta-e lapse rates within the isentropic lift, am
anticipating convective snow which will result in snowfall rates
around two inches per hour. As mentioned, not quite sure where the
narrower band of heavier snow will be, but expect it to be on the
western part of the broad area of moderate to heavy snow.

The moderate to heavy snow tonight combined with breezy winds
should lead to periods of whiteout conditions. Considered
starting the blizzard warning Sunday morning when winds would be
much stronger, but decided to start it this evening due to
potential for whiteout conditions in the increased snowfall rates. On
a side note, Goodland had half mile visibility in moderate snow
with 30 MPH wind gusts this morning, so whiteout conditions
should easily occur as winds increase late Saturday night and
Sunday.

Along with the heavy, wet snow a few high wind gusts may occur
after midnight along Highway 27. Am expecting the worst winds to
be Sunday, but decided to start the high wind warning early due to
the potential for a few high wind gusts occurring overnight in
the shallow mixed layer.

Sunday morning the moderate to heavy snow will continue and winds
will increase. Soundings show 50kts about 1500ft. AGL within the
mixed layer. Being very close to the ground, foresee these winds
easily reaching the surface along the Highway 27 and 25 corridors.
Can`t rule out wind gusts of 60 MPH elsewhere in the blizzard
warning area, however have highest confidence of wind gusts of
60-65 MPH in the high wind warning area. Winds will be strongest
in the late morning/early afternoon then gradually decline,
becoming breezy Sunday evening. The heaviest snowfall will be in
the morning and early afternoon when instability and lift will be
strongest. The combination of very strong winds and moderate to
heavy snow will lead to blizzard conditions.

Sunday evening the snow will exit the forecast area as subsidence
and drier air move in. Warnings could end earlier, but for
simplicity have them ending when snow ends.

Impacts...The heavy, wet snow combined with strong to very strong
winds will lead to strained tree limbs and power lines, with both
possibly breaking. The very strong winds Sunday will lead to
whiteout conditions for most of the day. Roads may close due to
the poor driving conditions. Preparations should be made for
possible power outages from this storm.

.LONG TERM...(Monday through Saturday)
Issued at 151 PM MDT Sat Apr 29 2017

Going into the extended period...models continue in agreement for
the beginning of the week on Monday with weak ridging in place over
the area...bringing dry conditions...in place of the winter storm
that affected the region this weekend. Dry conditions are short
lived as a quick moving shortwave will dive southeast from the north
central Rockies Tuesday night...across the central Plains Wednesday
and exit by Wednesday night. Strong H5/H7 ridging will replace the
exiting shortwave for the remainder of the week into Saturday...
setting the area up for a warming trend and dry conditions.

Little break in cloud expected on Monday between the two expected
system so the area will be looking at below normal highs mainly in
the 50s.

Going into Tuesday...thickening cloud cover expected from NW to SE
as shortwave approaches. Chance for showers will increase into the
overnight hours and on into Wednesday. Shortwave traverses the CWA
just ahead of an inverted surface trough. This trough was progged to
be a bit further south and ahead of shortwave yesterday putting
focus for major precip SE of the CWA. Latest runs in more tandem
with bringing higher QPF to the area. Extensive cloud cover will
prohibit -trw so will leave out mention of. Western portions of NE
Colorado could see a few hours of -sw w/ no accum around 12z
Wednesday.

Clouds and precip on Tuesday/Wednesday will afford the region below
normal temps with only highs reaching into the 50s. With the
approach of the H5/H7 ridge Thursday into Saturday...the area will
see highs Thursday ranging in the upper 60s to near 70F. But for
Friday and Saturday...mid and upper 70s on tap. Several locales
could even see an 80F reading. Overnight lows will transition from
the 30s thru mid week...to 40s to end the week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1123 PM MDT Sat Apr 29 2017

Conditions will continue to deteriorate through the overnight at
both KGLD and KMCK as upper low approaches and snow increases in
coverage and intensity. Northerly surface winds will increase
overnight as well, with gusts to 50kts possible by sunrise through
early afternoon. Occasional blizzard conditions will be possible
due to snow and blowing snow. The system will begin to wind down
late Sunday afternoon and Sunday evening.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Blizzard Warning until midnight MDT /1 AM CDT/ Sunday night for
     KSZ001>004-013>016-027>029-041-042.

     High Wind Warning until midnight MDT /1 AM CDT/ Sunday night for
     KSZ001-002-013-014-027-028-041-042.

CO...Blizzard Warning until midnight MDT Sunday night for COZ091-092.

     Winter Weather Advisory until midnight MDT Sunday night for
     COZ090.

NE...Blizzard Warning until midnight MDT /1 AM CDT/ Sunday night for
     NEZ079>081.

&&

$$

SHORT TERM...JTL
LONG TERM...JN
AVIATION...024



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