Area Forecast Discussion
Issued by NWS Goodland, KS
FXUS63 KGLD 302300
Area Forecast Discussion
National Weather Service Goodland KS
500 PM MDT TUE AUG 30 2016
.SHORT TERM...(This afternoon through Wednesday)
Issued at 128 PM MDT Tue Aug 30 2016
The remnants of the closed mid/upper low (now weakened)are over
northeastern Colorado, with weak troughing in place across our CWA.
At the surface low pressure is centered over southeast Colorado,
and high pressure is over south central Nebraska.
Precip this afternoon-Tonight: Showers/thunderstorms are in the
process of increasing in coverage with steepening lapse rates
beneath h7/h5 trough. MUCAPE ranges from 1000-2000 J/KG (highest in
our west) and this could support a few marginally severe updrafts.
Shear is very weak lowering confidence in a more organized severe
threat. Better coverage is currently tied to mid level circulation
and cold pool alfot, and HRRR/RAP seem to have picked up on this
trend. There is a lot of potential moisture in place (PWATs
approaching 1.5) representing anomalously high values for this time
of year. Combined with weak flow aloft/slow storm motions this
raises the possibility for heavy rain/flash flood potential.
Coverage is still a question and as lapse rates decrease we may not
see a prolonged heavy rain threat. This will need to be monitored,
though confidence is not high enough for flash flood watch.
Precip Wednesday: Pattern changes very little through Wednesday,
with isolated to scattered showers/thunderstorms possible. As has
been the case forcing will tend to be weak through most of the
period, with timing/position of vorticity maxima aloft uncertain.
Guidance also continues to vary on precip signals and fine tuning
better coverage will likely be difficult outside of a 6hr window. I
kept slight chance/chance PoPs in place favoring a consensus
approach placing higher PoPs mainly in the east.
Regarding fog potential: Boundary layer will remain very moist due
to weak easterly flow. As low levels decouple after sunset we should
start to see fog redevelopment (at least by late evening) and some
guidance is showing the potential for dense fog late
tonight/Wednesday morning. Areas of fog was added, and we will need
to monitor trends.
Regarding temperatures: Highs should be very similar Wednesday as
the same pattern and roughly the same air mass will be in place
(highs in the 70s to near 80). Stratus may help insulate low levels
tonight lowering confidence in low temperatures. I stuck to blends
trending similarly to the last few nights (50s west to mid 60s
.LONG TERM...(Wednesday night through Tuesday)
Issued at 204 PM MDT Tue Aug 30 2016
Unsettled weather continues through most of the long term period as
the region goes from the influence of an upper ridge to a trough.
Temperatures rise through the weekend before potentially dropping
off again early next week.
Wednesday night through Friday night: A cold front backs into the
High Plains from the northeast Wednesday night, bringing drier air
to the region. As the dry air advects in behind the front, chances
for precipitation decrease from the east while chances ahead of the
front, where moisture is more plentiful, persist. May see some
lingering precipitation Thursday before things dry out in time for
Thursday night and Friday. Meanwhile the pattern starts to change
aloft. An upper ridge progresses from the Rockies to the Midwest and
weakens as a trough advances onto the west coast. As the trough
nears the Plains on Friday, flow becomes southwesterly and a
shortwave ejects towards the region, generating shower and
thunderstorm chances Friday night.
Saturday through Tuesday: An area of surface high pressure behind
the cold front pushes east, allowing temperatures to rise over the
weekend as southerly flow draws moisture back north. In the
meantime, a surface trough forms lee of the Rockies and will be a
focus for storm development early in the extended. The
aforementioned upper trough over the western CONUS continues east
towards the Plains through the end of long term and an extension of
it digs further south. Periodic chances for showers and
thunderstorms are anticipated through the end of the forecast
period, with flow aloft remaining southwesterly and disturbances
ejecting from the upper trough onto the Plains. Guidance suggests
another cold front passes through the area late Monday into Tuesday,
increasing precipitation chances once again. Will continue to
monitor changes in front timing and position.
Temperatures start out in the upper 70s to low 80s on Thursday and
steadily climb into the mid 80s to low 90s by Sunday as surface high
pressure slides east and winds turn southerly. Expect another cool
down next week as a cold front approaches, bringing highs back down
into the low 80s (and maybe some 70s) by Tuesday. Lows stay
generally in the mid 50s to mid 60s, with some eastern locations
only falling into the upper 60s this weekend.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 500 PM MDT Tue Aug 30 2016
For KGLD, vfr conditions expected from taf issuance through
approximately 05z. There is a possibility that should a
shower/thunderstorm move directly over the terminal that
conditions will quickly become ifr in moderate to heavy rain.
Winds could also gust 25-30kts. Otherwise winds generally from
the east- southeast under 10kts. From 05z-15z am expecting a
return of ifr/vlifr conditions in br/fg and cigs. Trended timing
toward last 24 hours and latest hrrr guidance. After 16z cigs
expected to return to vfr with winds from the east-southeast under
For KMCK, vfr conditions expected from taf issuance through 07z.
There is a possibility that should a shower/thunderstorm move
directly over the terminal that conditions will quickly become ifr
in moderate to heavy rain. Winds generally from the east around
5kts. From 08z-`7z am expecting a return of ifr/vlifr conditions
in br/fg and cigs. Similar to KGLD trended timing toward last 24
hours of observations and latest hrrr guidance. After 18z cigs
expected to return to vfr with winds from the east around 7kts.