Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 172342
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
542 PM MDT Mon Jul 17 2017

.UPDATE...
Issued at 530 PM MDT Mon Jul 17 2017

Storm activity continues its trend of being slower than model
data suggests. Based on current radar trends and near-term data,
have trimmed rainfall chances to east of Highway 83. Have my
doubts storm coverage will be very extensive due to dry air moving
in behind the storm cluster. Considered cutting rainfall chances
in half, but did not want to be too aggressive just incase the
storms are able to overcome the dry air advection for a short time
over the eastern counties.

A few isolated storms have tried to develop just west of the main
group, but the dry air has limited there coverage and duration.
While storms will be possible this evening for the eastern part of
the forecast area, the majority of the storm activity will be to
the east of Red Willow, Norton and Graham counties.

&&

.SHORT TERM...(This afternoon through Tuesday)
Issued at 245 PM MDT Mon Jul 17 2017

Upper low that had been in eastern Colorado for the last 3 days
finally weakened and moves out into the plains early this morning.
Latest WV imagery shows this weakened mid level feature over
southwest Nebraska and northwest Kansas, with subsidence spreading
into our CWA from the west in it`s wake. SHowers/thunderstorms have
developed in the eastern part of our CWA near this feature.

This afternoon-tonight: Moderate instability will be in place across
our entire CWA this afternoon and early this evening, however any
thunderstorm activity should be confined to our east closer to the
main axis of forcing. Due to very moist air mass in our east and
consensus of short range models showing this activity developing
into a slow moving cluster there is some concern for localized flash
flooding. Latest trends in radar/satellite seem to indicate that
showers/thunderstorms may remain further east than most guidance had
indicated, but potential still exists for a few severe storms across
our eastern CWA through the evening.

Tuesday: West-southwest flow develops as ridge shift back into the
plains. This may allow for a weak mid level shortwave trough to
passing into our northwest by late Tuesday afternoon, and high
models are showing activity beginning to develop into the western
part of our CWA. This activity will tend to be high based with
isolated wind severe gusts the main threat.

Regarding heat advisory: Confidence is high that heat index values
will be 105 or higher Tuesday afternoon across our east and northern
locations along the Republican River valley. Based on coordination
and flexibility allowed by directive criteria I extended advisory to
include locations where 103 is likely and 105 may be possible. I
considered issuance of advisory to include nighttime periods through
Thursday, as overnight heat index values may not decrease below 75.
After coordination we limited the current advisory to Tuesday
afternoon/early Tuesday evening for now. This could be extended
based on trends and confidence.

.LONG TERM...(Tuesday night through Monday)
Issued at 143 PM MDT Mon Jul 17 2017

Tuesday night a weather disturbances will graze around periphery of
upper ridge. This may produce showers and slight thunderstorm
chances for the far northern area of our CWA, Otherwise expect dry
conditions.

Wednesday and Thursday high pressure will influence the region with
a very hot air mass. This will produce mostly dry conditions with
high temperatures reaching from the lower 90s to the around 105,
with the hottest areas being mostly extreme southwest Nebraska and
western Kansas. Some area along the state line may reach up to
around 100. Low temperatures through this time frame will drop into
the lower 60 to middle 70s (west to east). A Heat Advisory will most
likely be issue during this time with the area of focus being along
and east of a line from near Benkelman Nebraska to Hoxie and Gove
Kansas. Please watch out for more details if/when the Heat Advisory
is issue.

Thursday night and Friday: Instability will begin to increase slowly
from the west and northwest along a boundary that looks to enter our
region. A few thunderstorms could form mainly in the far
northwestern corner of the CWA. This boundary looks to move further
southeastward into our region and weaken, bringing thunderstorm
chances further into our region with a few stronger storms possible.
Temperatures on Friday will be well above average, climbing into the
upper 90s to just over 100 degrees.

Saturday through Sunday: A cold front looks to move through the
region on Saturday. This will most likely produce more widespread
thunderstorm chances during the afternoon and evening hours as the
front slows down over our CWA. The environment that is expected with
this frontal passage does support the development of a few strong to
severe thunderstorms along and ahead of it. Another round of
thunderstorms looks to develop Sunday afternoon as the front slowly
moves out of the region.

On Monday dry conditions look to return to the local areas as
another ridge of high pressure build over the region.

High temperatures Saturday through Monday will be much cooler than
the past few days, with highs generally reaching the middle 80s to
middle 90s with Saturday being the warmest day of the three.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 530 PM MDT Mon Jul 17 2017

VFR conditions forecast for the TAFs. Main focus is the
possibility of thunderstorm activity for KMCK in the next few
hours. Currently have low confidence of a storm moving over the
site due to how isolated the storms will be. The bulk of the storm
activity will be well east of the site, with more
isolated/scattered storms expected near KMCK. Due to the challenge
of trying to correctly time storm activity the past couple of
nights, continue to have low confidence in timing of these storms.
The trend with storm activity has been slower than what current
data shows, which causes difficulty in trying to provide accurate
timing. Any storms near the site should end around 2z or 3z,
unless the storm activity will be slower than what is currently
shown. Otherwise dry, hot weather will begin for the rest of the
work week.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory from 1 PM to 8 PM CDT Tuesday for KSZ002>004-
     014>016-028-029.

CO...NONE.
NE...Heat Advisory from noon MDT /1 PM CDT/ to 7 PM MDT /8 PM CDT/
     Tuesday for NEZ079>081.

&&

$$

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



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