Area Forecast Discussion
Issued by NWS Goodland, KS

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000
FXUS63 KGLD 222107
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
307 PM MDT Wed Mar 22 2017

.SHORT TERM...(Today through Friday)
Issued at 345 AM MDT Wed Mar 22 2017

Upper ridge axis shifts slightly eastward today but still remains
over the area resulting in above normal temperatures. Only
limiting factor will be cloud cover, which should erode west to
east through the day. So kept cooler temperatures in eastern areas
while northeast Colorado will warm well into the 60s. No fire
weather concerns today due to persistent southeast winds and
higher dew points. Low level moisture return overnight and weak
shortwave trough climbing the ridge will result in a few light
rain showers which may skirt the eastern part of the forecast
area late.

Large scale forcing gets underway Thursday afternoon with approach
of the deep system in the Four Corners which will emerge onto the
southern and central plains. Still considerable differences
between the models on the mesoscale set up for Thursday afternoon.
NAM has the dry line/surface trough near the Kansas and Colorado
border while GFS has it much further east near Hill City.
Instability axis will be along and east of wherever the dry line
sets up, with weak to moderate instability but excellent deep
layer shear. However, lower levels will be quite dry. Might see a
few severe storms with large hail and strong winds, but low
confidence on location. The other concern Thursday afternoon will
be fire weather. Lowest humidity and strongest winds will be in
northeast Colorado and adjacent counties in Kansas and Nebraska.

Instability gradually weakens Thursday evening with thunderstorm
threat diminishing, but attention shifts to precipitation type on
the back side Thursday night and Friday. NAM continues to be the
most aggressive model with rain changing to snow or a mix, and
possibly strong winds, as far east as Highway 25 by Friday morning.
Surface based layer will be above freezing, so even if a change
over occurs it will melt on contact, so little if any accumulation
anticipated at this point. However, will need to monitor the wind
speeds on Friday as the NAM suggests it will be close to high
wind warning criteria. Precipitation chances will continue into
Friday night with this slow moving, wound up system, with the
rain/snow line slowly moving eastward.

.LONG TERM...(Thursday night through Wednesday)
Issued at 305 PM MDT Wed Mar 22 2017

Complicated weather situation with strong closed upper low still
expected to move across the Plains with high impact weather
possible Thursday night through Friday.

Thursday evening: Thunderstorm coverage should increase along/east
of dry line through the early evening period with strong effective
shear values in the 40-55kt range possible. Discounting GFS which
appears to have mixed dewpoint too far east, NAM and ECMWF show at
least moderate instability and this could support supercell
development and large hail and particularly damaging winds
possibly merging into a cluster or line as it shifts east ahead of
large upper low. Tornado threat would be limited to early evening
period before low levels stabilize as LLJ increases.

Thursday night-Friday night:

Regarding precip coverage and amounts: Occlusion rotates over our
CWA with deformation zone settling over northeast Colorado where
coverage or rain increases late Thursday night through Friday.
Latest NAM has trended towards GFS/ECWMF position for upper low
which keeps this main precip area in our western CWA. In our east
a dry slot is shown to rotate northwest and could limit coverage
and amounts. While CAPE decreases through Friday, mid level Theta
E lapse rates remain negative and at least isolated thunderstorms
will be possible. Low level lapse rates and SB CAPE may reload if
stratus does not develop (which ECMWF/GFS keep stratus clear in
our east). This could result in showers/thunderstorms redeveloping
and filling in our east.

Regarding Winds Friday: Strong winds may develop and both NAM and
GFS show BL winds at least near 40kt (along with statistical
guidance) by midday Friday in our west. GFS is significantly
higher with BL winds 50 kt. Even assuming mixing is limited we
may see HWW conditions. Better mixing and the stronger GFS
solution may place this potential further west. I`m holding off
on a High Wind Watch for now as NAM may not be as certain. This
needs to be monitored.

Regarding precip type and temperatures Friday: Models show Max Tw
in the lowest 3m around 3C (or lower) where the deformation band
sets up, and this could allow for a mix or transition to snow
across our west and where moderate to heavy precip occurs
generally along/west of Hwy 27 we could see light snow
accumulations. If snow occurs and rates are high enough this
could combine with the strong winds to produce near Blizzard
conditions. Confidence is low due to uncertainty on the
transition, and due to the wet nature of any snow it will take
higher rates to achieve reduced visibilities. There is time to
fine tune based on changing trends, so no highlights are planned
at this time.

Saturday-Tuesday night: Active pattern remains in place across
the plains, with a series of closed lows develop and tracking near
or south of our CWA. We will continue to see returning
precipitation chances Monday night through Tuesday. Due to the
projected tracks better amounts/coverage may remain south, but
these periods have the potential for beneficial precipitation to
occur.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1130 AM MDT Wed Mar 22 2017

KGLD, mvfr cigs expected from taf issuance through about 21z or so
then a scattered deck around 2500` and some higher clouds. Winds
generally from the south gusting near 30kts. From 01z-05z winds
remain gusty from the south, after 06z stratus and possibly some
reduced visibilities move in from the south creating ifr and
possibly vlifr cigs through 16z. Winds continue to gust near 30kts
from the south. After 17z winds veer to the southwest and gust
near 30kts with stratus pushing east of the terminal.

KMCK, vfr conditions expected from taf issuance through about 05z
with cigs just above mvfr category, winds from the southeast
around 15kts and gusty. From 06z to 16z cigs fall to mvfr and ifr
category with some fog also expected as stratus moves in from the
southeast. Winds hover around 12kts from the southeast. After 17z
winds veer toward the south and gust 20-25kts with cigs becoming
vfr.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from noon MDT /1 PM CDT/ to 7 PM MDT /8 PM CDT/
     Thursday for KSZ001-013-027-041.

CO...Red Flag Warning from noon to 7 PM MDT Thursday for COZ252>254.

NE...Red Flag Warning from noon to 7 PM MDT Thursday for NEZ079.

&&

$$

SHORT TERM...024
LONG TERM...DR
AVIATION...99


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