Area Forecast Discussion
Issued by NWS Goodland, KS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGLD 301732
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1132 AM MDT Sun Apr 30 2017

.UPDATE...
Issued at 1051 AM MDT Sun Apr 30 2017

This is a very dangerous and high impact storm. Currently have
snowfall rates of 3 inches/hour reported under heavy band of snow
near Herndon, KS.  Snowfall reports under band in Colby were
around 20 inches. Am expecting the current conditions to
continue into the early afternoon then improve from southwest to
northeast. Subsidence is eroding east edge of broad band. This
will continue into early afternoon, but should remain along
Highway 83, then build back east after that as storm system lifts
north/northeast later this afternoon.

High winds still can occur until mid afternoon. Will see how winds
are doing then and address high wind warning.

Many locations with no power, many roads closed. Anywhere
moderate/heavy snow is falling blizzard conditions are being
reported.

&&

.SHORT TERM...(Today through Tuesday Night)
Issued at 337 AM MDT Sun Apr 30 2017

Mid-upper low is centered near the OK/TX Panhandles with plume of
deep moist flow around the northern and western extend. System is
organizing and snow accumulations are beginning to increase in areas
of higher DBZ returns on radar. Lighter snow is struggling to
accumulate due to warm ground temps.

Regarding snow amounts: Warm ground temps and lower SLR will play a
role in limiting potential amounts. At the same time all guidance is
still showing TROWAL/deformation band across our central/southeast
CWA and there is an axis of instability that will feed into this
band from the east southeast (lighting already observed at Hays and
by ENTLN/NLDN). There is the potential for high snowfall rates
within this band (in excess of 1" per hour) will be possible and
this should easily overcome these limitations. There will likely be
a hard cutoff between higher accumulations and almost no
accumulation due to the ground temp factor and narrower axis of more
intense snow that may develop. A major question will be rain/snow
line which lowers confidence in amounts as at time rain is being
reported with temps as low as 34F. Wet bulb profiles do cool with
max Tw through 0-6km layer near 0C by 12Z across our central CWA.

Trend in guidance favors locations generally along/east of Hwy 27
through our east and have trended down across our west and
northwest. Peak of the event appears to be from now (roughly 09Z)
through 18Z, though there are indications this band may linger in
our east/northeast into the evening before ending as occlusion
stretches and H5/H7 low shifts east. It still appears likely we will
see an axis of around 10" (assuming mainly snow within band). Models
are showing very high QPF along the main band and if this verifies
and falls as snow we could see significantly higher amounts than the
ongoing forecast calls for. Confidence is just not there considering
all factors with this system.

Regarding wind/blizzard conditions: Guidance still showing favorable
axis of strong winds in between Hwy 27/Hwy 25. GFS is highest with
BL winds in the 50-53kt range which may be high (based on VAD
winds), but even NAM would support possible gusts around warning
criteria. Windy conditions expected to coincide with snow should
result in reduced visibilities. Best chance for blizzard conditions
will likely be where moderate to heavy snow occurs, and confidence
is lower that we see this in eastern Colorado (though I also can`t
rule this out).

Main changes to this forecast update were to lower snow amounts in
eastern Colorado. No changes planned at this time to hazards as
system is beginning to organize and I would like to see how real
world obs/trends match with ongoing forecast amounts/visibilities.

Monday-Tuesday night: Period of subsidence should keep conditions dry
through Monday. By monday night forcing and limiting moisture
advection may support showers. Best chances will be when main
shortwave trough swings through the region Tuesday-Tuesday night.
Moderate rainfall may be possible. Air mass moderates through these
periods, however any deeper snow accumulations will likely throw off
temp forecast. Potential is for highs in the 60s (maybe near 70),
but confidence isn`t high across our NW KS and SW NE counties.

.LONG TERM...(Wednesday through Saturday)
Issued at 233 AM MDT Sun Apr 30 2017

There will be some chances for rain during the day Wednesday as a
positively tilted trough transverses the CWA. Not expecting huge
amounts of QPF. Could see around tenth of an inch in our eastern
counties.

The remainder of the extended looks to be quiet as upper level
ridging dominates the weather here in the Central High Plains.
Temperatures look to warm through the period and should be above
normal, peaking on Sunday with highs near 80.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1126 AM MDT Sun Apr 30 2017

IFR to VFR condition forecast for the TAFs. Heavy band of snow
currently over KGLD should linger over the site for the next hour
or so. Otherwise conditions should improve some for both sites
by mid to late afternoon as storm system moves northeast. With
KGLD on the west edge of the blizzard conditions, conditions will
waver between MVFR and IFR during the afternoon before snow ends.


&&

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

     High Wind Warning until midnight MDT /1 AM CDT/ tonight for
     KSZ001>003-013>015-027>029-041-042.

CO...Blizzard Warning until midnight MDT tonight for COZ091-092.

     Winter Weather Advisory until midnight MDT tonight for COZ090.

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

&&

$$

UPDATE...JTL
SHORT TERM...DR
LONG TERM...SME
AVIATION...JTL


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.