Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 250834
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
234 AM MDT MON JUL 25 2016

.UPDATE...
Issued at 926 PM MDT Sun Jul 24 2016

Lines of storms have now merged into one segment as they continue
to move east. Soundings indicate the best elevated instability
will be over the south half of the area, possibly extending to the
north. Models agree the best chance for rain will be over the
southern half of the Tri-State Area so have trended rainfall
chances that direction. Soundings also suggest there is enough
instability for this line of storms to continue across the area
through the night. Have rainfall chances gradually lowering over
the east half of the Tri-State Area due to line of storms moving
further from upper level short wave trough over Southwest Kansas.

With storm activity moving east of the watch area and no
indications of severe wind gusts for awhile now, will cancel the
watch. Heavy rainfall will be the primary concern with this line.

UPDATE Issued at 747 PM MDT Sun Jul 24 2016

Extended the severe thunderstorm watch one more hour due to wind
gusts in thunderstorms still nearing 60 MPH occasionally. Storms
should continue to weaken as they move east.

UPDATE Issued at 533 PM MDT Sun Jul 24 2016

Updated the chances for rainfall for the evening based on latest
data and storm trends. As storms progress east they will enter a
corridor of much higher CAPE ranging from 1000-2500j/kg as evident
on SPC Mesoanalysis. Am thinking this corridor is along the
frontal boundary and drapes southeast following the front into
Southwest Kansas. Storms are also moving into deep layer shear of
25-45 KTS or so. Am thinking storms will continue to increase in
intensity as they move east. However east of the KS/CO border the
environment becomes more stable north of Highway 40. The storms
will weaken as they move into the more stable air. The question
is how far east will they remain severe before weakening, thus
the reason for including a tier of KS counties in the watch.

Storm activity should propagate southeast following the corridor
of higher CAPE values into Southwest Kansas where lift will also
increase along the front by mid evening. By this point the deep
layer shear will have moved further north or will be in the
process of decreasing, causing the storm intensity to decline
leading to more of a heavy rain threat.

There is some elevated instability over the southeast quadrant of
the Tri- State Area during the latter half of the evening, so
some chances for storms are justified north of the front. However
believe the majority of the storm activity will be south of the
Tri-State Area during the latter half of the evening.

&&

.SHORT TERM...(This evening through Monday)
Issued at 1238 PM MDT Sun Jul 24 2016

Thunderstorms will develop later this afternoon in northeast
Colorado in the post frontal upslope regime as a weak shortwave
trough ejects out of the Rockies. Instability axis will reside
along the cool side of the front located roughly along the western
and southern boundaries of the forecast area. Deep layer shear
will be 30-40kts. These parameters suggest a few severe storms
will be possible and SPC accordingly raised the risk level to
slight. Although some of the short term convective models have
backed off on their QPF the synoptic scale models still show
copious QPF this evening in the western third. Given mean 0-6km
winds of 5kts or less, slow-moving storms will be possible with
locally heavy rainfall. Some models show 3"+ in northeast
Colorado. Will carry likely pops in Colorado tapering to chance in
northwest Kansas and slight chances in southwest Nebraska where
instability is very limited. Storms should wind down after
midnight as they trek southeast and out of the local area. Some
low clouds and perhaps patchy fog will develop around sunrise
Monday morning with persistent light upslope winds and low level
moisture.

Upper heights actually rise on Monday as the ridge over the Four
Corners appears to briefly nudge northward...perhaps aided by
subsidence behind the convective complex. As a result, think
Monday will be dry during the day with the next upper disturbance
not arriving until Monday night. Temperatures will once again be
near to slightly below normal.

.LONG TERM...(Thursday through Monday)
Issued at 226 AM MDT Mon Jul 25 2016

AT the beginning of the extended period there is an area of high
pressure aloft over the southwestern U.S. along with a deep
trough over the Mississippi valley region. This will produce a
northwesterly upper level flow over the High Plains into the weekend.

Temperatures are expected to remain near to somewhat above normal
through Saturday. Chance of showers and thunderstorms are possibly
during the evening and overnight hours, for the rest of the work
week, due to diurnal convective activity moving off the Rockies and
into the plains. Friday night continues to be the favorite time
period for the highest possibility of thunderstorms and rain
showers across the Tri-State area, as a couple of the strong short
wave troughs move across the region.

Starting Sunday, high pressure aloft amplifies over the high
plains and into the northeastern U.S. This causes the upper air
pattern to become more southwesterly towards the end of the
period. resulting in drier conditions and temperature reaching
above normal as this upper level high pressure influence the area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1125 PM MDT Sun Jul 24 2016

VFR conditions forecast for the TAFs. Winds will be somewhat
erratic tonight due to the lingering storm activity. Current winds
at KGLD are breezy behind the exiting rainfall. These winds should
decline over the next few hours as the rain moves further from the
site. Am thinking that once the storm activity moves far enough
east of the sites in the next couple hours the winds should return
to the prevailing easterly direction and remain there through the
rest of the TAF. There is a chance for thunderstorms again during
the afternoon, however these storms should be isolated and
confined to the evening hours.


&&

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

$$

UPDATE...JTL
SHORT TERM...024
LONG TERM...BW
AVIATION...JTL


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