Area Forecast Discussion
Issued by NWS Goodland, KS

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235
FXUS63 KGLD 232005
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
205 PM MDT Sat Sep 23 2017

.SHORT TERM...(Today through Monday night)
Issued at 426 AM MDT Sat Sep 23 2017

Main forecast issues will be chance of severe thunderstorms through
this evening along with timing/amount of precipitation through the
period with secondary issue of how cool to make the high
temperatures. Satellite showing an amplified and slow moving pattern
from the Pacific into the western Atlantic. Analysis and satellite
continue to show that moisture is increasing into the area.

At jet level...models are close with the Canadian, Nam, and Ecmwf a
little better. At mid levels...the models were close. The high resolution
output was doing well on the surface field the best, especially
the location of the front near/over our area.

Overall the trend of a slower to non-existent eastward
progression continues over the last 3 days. Also some kind of mid
level circulations to our west and is also a little south from the
previous run.

Today/tonight...Main jet axis still well to the west of the area
with a secondary jet area starting near/over the western end of our
area at the beginning of the day and makes little if any progress
through the rest of the day as the main jet axis inches closer.
Right rear quadrant of the jet starts affecting the western half of
the area during the evening and especially during the overnight.

Mid level lift also does not increase/start moving east until later
this afternoon into this evening. High resolution output, especially
the Nam and Arw are catching the position of the slow moving front
the best. By the middle of the day this boundary is draped from
southwest to northeast across the area. The high resolution output
is in remarkable agreement with each other and matches up with the
large scale depiction of the mid and upper level lift. So blended
that high resolution output for the pop forecast through tonight.
This means the central and especially the western portion along and
west of the Colorado border will have the highest chance of
precipitation for the day with the far eastern portion seeing the
least amount.

Deep lift works its way across the area during the night and
followed that trend with the high resolution output. Much above
normal precipitable water values continue through tonight. During
the daytime they are roughly near 1.5 inches. This decreases from
west to east to 1 to 1.5 inches during the night. So moderate to
especially heavy rainfall will be a threat and that is also
reflected in the continued slight risk for excessive rainfall issued
by WPC. After collaboration with neighbors, a long time since that
last significant rainfall, and seeing that the timing for the very
heavy rainfall is not until later this afternoon and early this
evening, decided not to issue a Flash Flood Watch. Day shift will
need to take another look at this.

Strong thunderstorms develop over the western portion of the area,
near the front, early in the overnight period. Severe parameters
have been improving for the last 3 days. Shear is much stronger, a
boundary is over the center of the area, and other severe composites
and parameters are giving a much better signal for today. So to add
to the heavy rainfall threat will be a severe threat.

Sunday/Sunday night...Right rear quadrant of the upper jet moves
across during the day. For the night, depending on which model you
choose, we have another right rear quadrant and/or a coupled jet
structure move across the area. The mid level lift and frontal
boundary slowly transition to the east through the period. The high
PWs, 1 to 1.5 inches, look to be confined to the east of the
Colorado border. So during this time the heavy rainfall transitions
to the eastern portion of the area and that is reflected in the day
2 excessive rainfall outlook.

Will have plenty of cloud cover and precipitation for the daytime,
so trended the high temperatures down from what the blend gave me.
If the Met and 2 meter guidance is right, I have not trended
temperatures down enough.

Monday/Monday night...Right rear quadrant affects through through
the day with little if any progress east. The right rear quadrant
moves slowly across the area through the evening with the area
coming under the influence of a left front quadrant during the
overnight hours. Continued mid level lift will continue. Area is in
a postfrontal environment. However, elevated instability is still
indicated. PWs continue to decrease and at this time only expect
light to moderate rainfall.

High temperatures from the blend range from 50s to upper 60s. At
this time that looks reasonable but those may still need to be
cooled.

.LONG TERM...(Sunday night through Saturday)
Issued at 205 PM MDT Sat Sep 23 2017

The extended period will start off with a wet period and then the
remainder of the week is expected to be dry. Sunday night through
Tuesday morning will be the wet period. The deep trough that has
been bringing moisture and precipitation to the region the prior few
days will still be impacting the region, and will not move east and
north of the CWA until Tuesday. The region is forecasted to receive
anywhere from 1 to 3 inches of rain.

Tuesday through Saturday are expected to be dry. The trough will
have already moved northeast of the region and northwest to zonal
upper level flow is anticipated over the CWA. For the most part, all
moisture will stay south of the area. There is a brief time on
Thursday where some moisture can sneak into the eastern Colorado
counties, but nothing significant is expected at this time.

Temperatures will be in the 50s and 60s on Monday and Tuesday, with
Monday being the cooler day. Wednesday through Saturday will stay in
the 60s and 70s, with Saturday being the warmest day.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1134 AM MDT Sat Sep 23 2017

VFR conditions with a low probability of MVFR conditions due to
lower ceilings will persist at GLD and MCK through the day today
and into the evening. MVFR conditions are expected as ceilings
lower around 13Z Sunday morning. The possibility of showers and
thunderstorms developing and moving into the respective TAF areas
increases through the afternoon and evening with the rain and
isolated thunderstorm expected to persist through the afternoon
and overnight hours into Sunday morning.


&&

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

$$

SHORT TERM...BULLER
LONG TERM...CLT
AVIATION...LOCKHART



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