Area Forecast Discussion
Issued by NWS Goodland, KS
FXUS63 KGLD 141728
Area Forecast Discussion
National Weather Service Goodland KS
1028 AM MST Sat Jan 14 2017
Issued at 1016 AM MST Sat Jan 14 2017
Based on the latest trends in guidance, I upgraded the winter
storm watch to a winter storm warning. The timing was also changed
to reflect a slightly later start time due to slower overall
movement of the system.
.SHORT TERM...(Today and tonight)
Issued at 502 AM MST Sat Jan 14 2017
Our forecast area is still on track for winter storm, however
changes were made to ongoing forecast to reflect latest trends.
GFS/GEFS remain outliers in evolution of upper level pattern and
ECMWF/NAM and other guidance were favored for timing, blends, and
A dry air mass is in place over our CWA roughly below 800mb. Mid to
high level moisture is increasing across the region, but forcing
remains weak. This dry layer will be prohibitive to measurable
precipitation through at least 00Z and there are some indications
in short range and high resolution guidance that this will not be
overcome until late tonight for the majority of our CWA. In fact
consensus of short range guidance would not support measurable
precipitation until after midnight for our entire CWA and then on
the far southeast until 12Z Sunday. ECMWF still supports potential
light freezing rain as early as 00Z, but confidence is diminished
in impacts for the majority of our CWA until later.
A colder near surface layer advertised by the NAM and implied by
much colder Tw from ECMWF/ARW/NMM may support more in the way of
sleet accumulations one may areas of moderate precipitation begin to
slide across our CWA. This would obviously decrease freezing rain
accumulations and shift impacts from being primarily focused on
power outages to just travel. In any case travel will be very
difficult once this event gets underway with worst conditions Sunday
ECMWF/NAM both show the closed low tracking Sunday night and Monday
in such a way as to support a deformation band forming in our
central or western CWA and a complete change over to snow Monday.
Based on conservative QPF/snow ratios we could see 8" or higher.
This may be dependent on the slower upper low track of ECMWF/NAM and
slightly better snow ratios. I trended snow totals upwards as
previous blends were being influenced downward by the GFS which
likely is not handling this track very well and is a large outlier.
SREF mean is near the current forecast, however the SREF plume shows
how large the spread between various members with minimal
clustering. Heaviest band may not impact as large of an area and
there is still the possibility that sleet could diminish totals.
This large ensemble spread is reflecting this uncertainty.
Regarding highlights: As a result in the drier early trend I delayed
the onset of the Ice Storm Warning until 00Z and the Winter Storm
Warning until 10Z. I am still confident in measurable
(potentially high impact) ice accumulations where the Ice Storm
Warning is in place, though if sleet dominates our amounts may
need to be trimmed. Regarding the Warning: Increased confidence in
freezing rain and sleet/snow amounts led to the upgrade of the
watch to a warning. Recent Hi-Res guidance agrees with persistent
ECMWF solutions. Snow amounts may need to be adjusted based upon
where the band of heavier snow sets up Sunday night/Monday
morning. Generally we are looking at 4 to 6 inches of snow in the
warning area with isolated higher amounts possible due to the
system moving a bit slower with each iteration.
.LONG TERM...(Tuesday through Friday)
Issued at 159 AM MST Sat Jan 14 2017
Forecast concerns will be affects of upcoming storm on temperatures
at the beginning this period, and the next chance of precipitation
toward the end of the period. Satellite showing a progressive flow
over most of the Pacific with an amplified/split flow over the
western portion of the North America.
Temperatures at the beginning of this period look to be problematic
depending on the extent/amount of ice/snow this upcoming storm will
drop on the area. There definitely looks like there will be a lot of
ice around over the current ice storm warning area. There is still
some uncertainty on how much snow and where it will fall. All in all
the entire forecast area looks to be covered with a decent amount of
snow and/or ice. So the first couple of days I reduced the the maxes
a few degrees. This will have to be looked at and adjusted again.
Through this entire period there is a big spread in both the
deterministic and ensemble output. This is all because the models
are having a hard time resolving what happens with the incoming
trough after it moves to our east. This also has affects on how the
models handle the end of the week trough. The deterministic output
at times toward the end of the period is out of phase with each
other. Currently the forecast builder gave me pops Friday and couple
of periods beyond. Depending on the deterministic output and the
ensemble output, they would indicate the possibility of
precipitation occurring 24 to 48 hours before that.
Because of this uncertainty and disagreement, left alone the pops
the forecast builder gave me. Hopefully the output can start getting
into better agreement.
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1028 AM MST Sat Jan 14 2017
For KGLD...mainly VFR conditions expected thru 12z Sunday with
decreasing ceilings due to approaching storm system. Looking for
ovc080-110 to drop to ovc050 during this time. Light precip will be
in the vicinity. From 12z Sunday onward...MVFR conditions worsening
to IFR by 17z Sunday. Looking for ceilings dropping from ovc030 to
ovc010...and 2-3sm in -FZRAPL. Winds...north around 5-10kts thru 22z
this afternoon then becoming ESE around 10kts.
For KMCK...mainly VFR conditions for much of the forecast period
with decreasing ceilings from ovc150 to ovc060 by 11z-15z Sunday. By
15z...MVFR conditions begin to encompass the area as light freezing
rain starts with ceilings dropping to ovc030. Conditions will worsen
after 18z. Winds...mainly light/variable thru 11z Sunday...then
becoming ESE around 5kts.
KS...Winter Storm Warning from 3 AM MST /4 AM CST/ Sunday to 7 PM MST
/8 PM CST/ Monday for KSZ001>003-013-014-027.
Ice Storm Warning from 5 PM MST /6 PM CST/ this afternoon to 11
AM MST /noon CST/ Monday for KSZ004-015-016-028-029-041-042.
CO...Winter Storm Warning from 3 AM Sunday to 7 PM MST Monday for
NE...Winter Storm Warning from 3 AM MST /4 AM CST/ Sunday to 7 PM MST
/8 PM CST/ Monday for NEZ079>081.