Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 231723
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1123 AM MDT Wed Aug 23 2017

.SHORT TERM...(Today through Friday)
Issued at 245 AM MDT Wed Aug 23 2017

Shortwave trough topping the ridge will provide weak forcing for
afternoon thunderstorm development today. Old surface front will
migrate off the Front Range and provide the focus for convective
initiation in northeast Colorado after 21z. Models forecast a
narrow band of moderate instability from near Limon to Julesburg,
dropping off quickly along the Kansas/Nebraska border. Deep layer
shear in this area will be around 25 kts. Due to the relatively
weak shear, chances for severe storms in northeast Colorado will
be marginal at best, with hail up to the size of quarters possible
with any stronger storm that develops. The 0-6 km winds are very
weak, around 5 kts, so storms will not be moving much and should
dissipate after sunset before reaching Kansas/Nebraska. Afternoon
high temperatures will be near/slightly above normal, with breezy
south winds from late morning through the afternoon.

The upper ridge flattens on Thursday as a more significant
shortwave trough moves across the central High Plains in the
afternoon and evening hours. Global models are quite wet,
especially Thursday night, with qpf bullseyes of 1 to 2 inches,
especially across northern portions of the area. As a result, have
bumped up pops to likely as this system moves across the area. As
for the severe threat, strong instability of up to 3500 j/kg is
forecast for the afternoon, but deep layer shear remains weak at
20-25 kts. However, with the stronger forcing from the shortwave
and good instability, a marginal risk for large hail and damaging
winds will exist, as well as a more localized threat for heavy
rain and flash flooding. Temperatures will continue to be near
normal.

On Friday, the upper ridge begins to rebuild over the central
Rockies and adjacent plains. Another weak shortwave trough comes
over the top in the afternoon and evening hours, providing low
chances for thunderstorms. Instability will be much weaker
compared to previous days, and deep layer shear remains weak at
20-25 kts, with a slight uptick noted in Nebraska to around 30
kts. Best chances for storms may be in Nebraska and far northeast
part of the forecast area, but with the weak instability severe
storms seem unlikely. Temperatures will remain near normal.

.LONG TERM...(Saturday through Tuesday)
Issued at 245 AM MDT Wed Aug 23 2017

Saturday: Surface trough axis will be situated near the KS/CO border
during the day. A series of shortwaves will traverse the area in the
NW flow aloft. Model soundings continue to show good parameters for
strong to severe storms during the evening across the CWA. May even
see a few supercells form in eastern and northeastern portions of
the area. Also, could see decent rainfall amounts based on 0Z GFS
PWATs (+1.50 in.) and 0Z ECMWF QPF amounts, with any storms that
form. Highs will be in the mid to upper 80s and overnight lows will
be near 60 areawide.

Sunday-Tuesday: The majority of this period should be dry. Models
are showing the potential for some showers and storms Sunday
afternoon, so kept slight chance PoPs in the forecast. Lift looks to
be negligible, but there is ample moisture in the lower levels to
get some precip. 0Z GFS theta-e fields are showing that the area may
get a weak backdoor cold front Monday into Tuesday. Looks to be a
dry frontal passage if it were to occur. Temperatures should be near
normal for the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1122 AM MDT Wed Aug 23 2017

Throughout the remainder of the TAF period, VFR conditions are
expected to prevail at the GLD and MCK terminals. Gusty winds will
diminish after sunset tonight.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...024
LONG TERM...SME
AVIATION...EV



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