Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 171158

Area Forecast Discussion
National Weather Service Goodland KS
558 AM MDT Mon Jun 17 2019

Issued at 547 AM MDT Mon Jun 17 2019

Just completed an update. Precipitation is slower to end in the
eastern portion than previously expected. So raised the rainfall
chances through mid morning.


.SHORT TERM...(Today through Wednesday night)
Issued at 438 AM MDT Mon Jun 17 2019

Forecast concerns chances of severe thunderstorms and flash flooding
into Tuesday night. Satellite showing an amplified flow from the
Pacific into eastern North America. The amplified over North America
is also in a split flow. Surface low is over southeast Colorado with
a surface trough extending to the east northeast across the far
southern portion of the area.

To the north of that synoptic boundary, a myriad of outflow
boundaries with continuing thunderstorms is present. Models started
out well and were close. However, the Nam was starting out slightly

Today/tonight...Weak flow aloft remains over the area through this
period. Because of this weak flow Effective shear is less than 30
knots. Also concerned of some caveats that could hinder
heating/increasing instability. First, rainfall is slowly moving
east and decreasing. There will be some lingering low chance in the
morning. As a result, models are holding onto a lot of leftover
cloud cover.

The air mass been worked over pretty good from yesterday, and may
not be able to recover very much if we do not get much heating. Also
there are a couple of convective circulations evident in this
mornings activity, and that will bring increased subsidence to the
area for most of the day. All the models are slow in bringing in
rainfall from the west due to the above and the slow movement.
Currently there is a slight risk for severe weather for the far west
and northwest portion of the area and this makes sense.

Many locations along the Nebraska and Kansas border received
anywhere from 1 to 3 inches of rainfall yesterday. However, no
flooding occurred. Precipitable water values are 1 to almost 1.5
inches. This along with the slower storm motions will create the
opportunity for locally heavy rainfall. Currently the northwest
half of the area is in a marginal risk for excessive rainfall.
Current output is pretty consistent in keeping a majority of the
rainfall to our north or in far eastern Colorado that did not get
much rain.

As a result am thinking the threat of for flash flooding will be
isolated at best, and decided not to issue a Flash Flood Watch. Day
shift will need to reassess this. No matter what there will be a
rather high chance for measurable rainfall, mostly over the
northwest half of the area which moves southwest to northeast across
the area.

Tuesday/Tuesday night...Weak right rear quadrant moves across the
area during the night. Models differ on how they develop/move the
incoming mid level trough through and out of the area. The Nam is
much slower in moving this system, and as a result produces a lot
more rainfall. The other output is more consistent, and is more
progressive and puts most of the rainfall to our north.

As a result kept some kind of chance going during this entire
period. However there is a high degree of uncertainty with this. No
matter what we should be cooler and more stable. So do not expect
a big threat from severe thunderstorms plus the threat for heavy
rainfall is much less as well.

High temperatures will be cooler than today but the models cannot
agree how much. I took the forecast blend and nudge it down a little.
Also north winds will increase behind the system.

Wednesday/Wednesday night...A low chance of precipitation is
expected during the day with a dry night. The blend looked
reasonable not only on the precipitation but also on the
temperatures so did not change.

.LONG TERM...(Thursday through Monday)
Issued at 335 AM MDT Mon Jun 17 2019

Thursday begins with zonal flow over much of the western half of the
U.S.. Throughout the day Thursday, a closed low moves east-southeast
over the northwest Plains forming a ridge over the east-central U.S.
The trough associated with the closed low extends into the
southwestern U.S. by Saturday. The trough axis moves across the Tri-
State region Saturday night into Sunday. The GFS shows an upper
level disturbance moving across the central U.S. Sunday evening. A
developing ridge moves across the central Plains Monday.

A series of surface lows are expected to move across the central
Plains throughout the extended forecast period bringing consistent
chances for showers and thunderstorms. High temperatures will be in
the 70s to low 90s with a cooler weekend in the forecast. Low
temperatures will be in the upper 40s to low 60s.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 547 AM MDT Mon Jun 17 2019

For Kgld, vfr conditions are expected until very late in the
period. Light and variable winds will shift to the south at 14
knots around 14z. Those winds will stay the same until 23z when
they increase to near 17 knots with gusts to around 26 knots. From
23z to 02z, thunderstorms will be close or approaching the site
and have vcts in there for now. From 02z to 07z, thunderstorms
should affect the site as winds shift to the southeast at 10 knots
with gusts to 19 knots. From 06z to 07z the thunderstorms will
end. At 07z the winds will shift to the southwest at 6 knots. At
10z those winds will shift to the west at 6 knots as mvfr
conditions develop.

From Kmck, vfr conditions are expected the entire period. The
winds will start out from the east at 6 knots. At 15z, the winds
will be southeast at 7 knots and then increase to 13 knots at 20z.
From 23z to 05z, thunderstorms will be in the vicinity of the
sites as the winds become more south and increase to near 15
knots. From 05z to the end of the period, thunderstorms will
affect the site through the end of the period as the winds become
east at 7 knots.




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