Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 182016

Area Forecast Discussion
National Weather Service Goodland KS
216 PM MDT Thu May 18 2017

Issued at 1226 PM MDT Thu May 18 2017

Just completed an update. Lowered pops for the measurable rain
along with everyone else for this afternoon. The main rainfall and
thunderstorms chances look to be in the far west and east this
afternoon. Also strong upslope flow has produced areas of fog and
drizzle so inserted that for the rest of the day. Also
temperatures, expect for maybe the far south and southeast, are
not expected to raise very much.

UPDATE Issued at 912 AM MDT Thu May 18 2017

Just completed an update. One change was to slow down the arrival
of precipitation. Per collaboration and latest model/observational
trends, reduced the pops this morning. Higher pops look to not
arrive until this afternoon. Other change was to lower maxes a
little. Looks like we will have stratus blanket most if not all
the area through the day which should cut down on heating.


.SHORT TERM...(Today through Saturday night)
Issued at 255 AM MDT Thu May 18 2017

The primary short term forecast concern is the possibility of
thunderstorms across the forecast area late this afternoon through
the overnight hours. The potential for severe thunderstorms ranges
from a marginal risk across much of the northwest sections of the
forecast area, to a slight risk across the southeast half of the
forecast area, and a small enhanced risk area across the extreme
southeast portion of the forecast area. The enhanced risk area is
southeast of a line from Scott City to Hill City Kansas. While an
isolated tornado can not be ruled out, the main threats will be
large hail and damaging winds with any storms that become severe.

A strong upper level low pressure system rotates through the
4-corners region this evening with a short wave trough rotating
around the low center expected to lift out across the central high
plains late this afternoon and evening. The main upper low lifts
through the central high plains region on Friday and into eastern
Nebraska and southeast South Dakota by Saturday morning. The
associated surface low deepens over the Texas panhandle region
today, stretches into eastern Kansas by Friday and lifts into
northern Missouri and southern Iowa by Saturday morning.
Thunderstorms are expected to develop across southern Kansas and
Oklahoma this afternoon with additional storms developing rapidly
across the region through the late afternoon and evening as the
frontal boundary currently across southern Kansas lifts north as a
warm front.

Scattered showers and thunderstorms will continue across the
forecast area on Friday and Friday evening as the low pressure
system moves across the region.  A marginal to slight risk of severe
storms is expected across the eastern half of the forecast area.
Showers and thunderstorms are expected to diminish across the area
from west to east after midnight Friday night.  As precipitation
diminishes, sky cover will also begin to diminish and overnight
temperatures will dip into the middle to upper 30s across the
western half of the forecast area.  With temperatures in the middle
30s across Colorado, there is a slight chance of locations along and
west of the Colorado border area seeing a brief rain and snow mix
after midnight Friday night along with some locations possibly
seeing a light frost.

Expect slightly warmer temperatures and dry conditions as low
pressure moves out of the region and is replaced by higher pressure
on Saturday and Saturday night.

.LONG TERM...(Friday night through Thursday)
Issued at 216 PM MDT Thu May 18 2017

Friday night-Saturday: Upper low transitions across our CWA. While
large scale forcing and good moisture should lead to good precip
chances through the evening Friday, there is less certainty after
midnight due to variances in track/evolution of mid-upper low. ECMWF
keeps upper low broadly closed or open and tracks further north
which would end precip chances much sooner. GFS is much stronger and
closes the low over our CWA. This would slow down exit of precip,
result in higher rates lasting longer, stronger winds, and even
support possible light snow accumulations in our far west (grassy
surfaces). NAM/GEM fall in between these solutions. For now I stuck
with mean trend as a best guess, which places emphasis on Friday
evening and has precip ending by midday Saturday.

Exit of precip will also impact radiational conditions and whether
we would see a threat of frost development in our west. Slower
solution is less likely to support frost, while faster solution

Sunday-Tuesday: A progressive pattern with NW flow over the Plains
remains in place through these periods with a quasi-stationary front
and passing shortwave troughs. A stronger negatively tilted mid-
upper trough passing through the Plains Monday-Monday night and
might bring our next best chance for showers and thunderstorms.
Temperatures will tend to be near normal through Monday for this
(near 70s highs, 40s for lows). Tuesday will be in a post frontal air
mass after a cold front passage Monday night, and highs should be
in the 60s with northerly flow through the day.

Tuesday night-Thursday: Models show a general trend towards dry
conditions, though GFS does keep a slightly northerly component
aloft which could support additional weak shortwave trough
passages. ECMWF shows ridging, and with drier air from the GFS
(despite better forcing) I was comfortable keeping dry conditions
during these periods. Temperatures should also slowly warm with
above normal highs by Thursday (near 80F).


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1141 AM MDT Thu May 18 2017

For Kgld...lifr/vlifr conditions are expected in rain, drizzle,
fog and thunderstorms until 12z. At that time mvfr conditions are
expected. East winds of 18 knots with gusts 26 knots will
decrease around 21z.

For Kmck...ifr/lifr conditions are expected through the period due
to low ceilings along rain, drizzle, fog, and thunderstorms. East
to northeast winds of 16 to 22 knots with gusts of 24 to 30 knots
are expected through 02z.




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