Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 281137
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
537 AM MDT SUN AUG 28 2016

.SHORT TERM...(Today through Tuesday Night)
Issued at 237 AM MDT Sun Aug 28 2016

As of 3 am CDT, 2 am MDT, skies across the Tri-State Region have
quickly become overcast over the past 3 hours due to expansive cloud
cover spreading in from the southwest. Latest WSR-88D radar imagery
indicates the only nearby precipitation can be found in southwest
Kansas. Temperatures are in the upper 50s to upper 60s. One thing to
note is T/Td spreads are much higher than yesterday, on the order of
3 to 8 degrees. At the surface, a weak lee trough is located just
east of the Rockies. Aloft, a weak shortwave is progressing across
southwest Kansas, likely helping to sustain current convective
activity. Another shortwave is moving north over central New Mexico.
This trough is ahead of the main upper level low, seen on water
vapor imagery pivoting across northern Arizona and southern Utah.

For this morning, fog potential is once again something to keep an
eye on. However, guidance has backed off on fog potential, something
I think is for good reason. That reason is expansive cloud cover
moving in from southwest Kansas. This will severely limit
radiational cooling compared to the clear skies that aided dense fog
formation yesterday morning. Due to the low confidence in fog
development, decided to remove fog mention from the forecast for all
locations except southwest Nebraska and extreme northeast Colorado
where dewpoint depressions are only 2-4 degrees at this hour.

Over the next 3 days, a series of upper level disturbances will push
through the region. The first comes this afternoon as a shortwave
trough slides in from New Mexico. Then, a weakening upper level low
spreads over the High Plains for Monday and Tuesday. These
disturbances should keep precipitation chances going from the early
afternoon hours to well after midnight each night. It is somewhat
difficult to pinpoint shower/storm development each day due to weak
forcing, the lack of any cap, and uncertainty on boundary/surface
trough locations. With this package, Tuesday seems to hold the best
chance for precipitation as the upper low remnants move directly
overhead.

With regards to severe weather potential, today holds the highest
threat for strong/severe thunderstorms. SBCape between 1500-2500
J/kg should be realized by this afternoon, accompanied by 850-500 mb
Lapse Rates of 7-8 C/km. Storms should be of the pulse-type variety
due to weak wind shear, generally less than 20 kts of 0-6 km bulk
shear. Widespread severe weather should not be anticipated today but
a few large hail or damaging wind gusts are possible. Instability
and lapse rates diminish some Monday and Tuesday. Combined with very
weak shear (10-15 kts), indications are most thunderstorms should
not be severe. A few strong/marginally severe storms can`t be ruled
completely out but seem quite unlikely.

The most impactful weather over the next 3 days should be heavy
rains and potentially flash flooding. Weak winds aloft are highly
indicative of slow storm motions. In addition, precipitable water
readings soar to the 90th percentile or higher, particularly Monday
and Tuesday. If storms become latched to any boundaries, flash
flooding could easily occur given the heavy rain rates likely to
occur and sluggish storm motion.

.LONG TERM...(Wednesday through Saturday)
Issued at 123 AM MDT Sun Aug 28 2016

A weak disturbance coming out of the central Rockies on Wednesday
combined with a moist low level southeasterly flow will result in
scattered thunderstorms. Weak instability/shear will keep severe
threat at a minimum. The ridge axis shifts a little further east
on Thursday, but difficult to find any kind of large scale forcing
for convection. Moisture/instability and shear profiles get
better, so if anything can develop there might be a marginal risk
for a severe storm. By the end of the week/start of the weekend
get into more of a southwesterly flow aloft as a stronger
disturbance moves through the northern Rockies. Associated surface
cold front will slide into the area Friday night and may be the
focus for convection through Saturday. Model details not in
particularly good agreement at that time range, so POPs will range
from slight to low chance.

Temperatures start the period slightly below normal but warm to
near normal by the end of the period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 537 AM MDT Sun Aug 28 2016

VFR conditions anticipated at both sites for most of the forecast
period. MVFR visibility possible at KMCK over the next 2-3 hours
but was not confident enough to place into TAF. This afternoon,
thunderstorms are expected to develop along the Colorado border,
spreading east through the evening. Uncertainty remains on where
storms develop because of nature of forcing (weak) associated
with the incoming disturbance. Due to high atmospheric water
content, any storms that are able to affect TAF sites could
produce heavy rainfall, leading to MVFR visibilities.

&&

.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...RRH
LONG TERM...024
AVIATION...RRH



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