Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 210802

Area Forecast Discussion
National Weather Service Goodland KS
202 AM MDT Wed Jun 21 2017

Issued at 1136 PM MDT Tue Jun 20 2017

Area of showers continues to progress toward the forecast area
from the west. Had anticipated the stable environment behind the
outflow boundary that had moved west to end any storm activity.
The activity has weaken but continues eastward. The lift from the
upper level short wave trough must be enough to overcome the
increasing stability to generate some rainfall. The rainfall will
slowly move east-southeast through the rest of the night and
gradually fade as the upper level short wave trough fills.

UPDATE Issued at 440 PM MDT Tue Jun 20 2017

Based on radar trends/model data, increased rainfall chances more
for Gove, Sheridan, Graham counties where thunderstorms are
expected to move. Based on the speed of the furthest west storms,
the storm activity should be east of Graham and Gove counties by
11 PM CT. There does appear to be a potential for redevelopment to
the west around 7 PM CT as the theta-e axis the increases to the
northeast. However this higher theta-e axis could be in response
to the ongoing storm development. If storms do not redevelop to
the west in the next couple of hours, storms will be east of
Graham and Gove counties by 9 PM CT.

Overnight another much weaker round of storms may move in from the
west, mainly north of Highway 36. Any storms that do develop will
not be severe and will be east of Red Willow/Norton counties by 8
AM CT. Not too confident this will occur, but wanted to atleast
put a mention of rainfall in the forecast.

UPDATE Issued at 329 PM MDT Tue Jun 20 2017

Updated forecast for increased thunderstorm and severe storm
coverage across the southeastern sections of the forecast area
for the next few hours as storms continue to develop and move
generally east southeastward.


.SHORT TERM...(This evening through Wednesday)
Issued at 1259 PM MDT Tue Jun 20 2017

The forecast concerns in the short term period are the hot daytime
temperatures and the potential for some storms to become severe as
isolated to scattered thunderstorms develop and progress across the
eastern sections of the area during the afternoon and evening hours
today and again on Wednesday.

Afternoon high temperatures approaching the century mark with
dewpoints across the eastern half of the forecast area in the lower
60s will produce an unstable atmosphere east of a line from Tribune,
KS to McCook, NE,  CU developing across southwest and west central
KS along and east of a surface trough will spread across north
central KS with scattered thunderstorms expected across the area by
mid afternoon. Some storms are expected to become severe during the
late afternoon and evening with large hail and damaging winds.

Overnight low temperatures stay in the lower 70s around the Hill
City area with lows in the lower to mid 60s across far eastern
Colorado tonight.

Temperatures warm quickly again on Wednesday morning with afternoon
high temperatures expected around the century mark east of the
Colorado border area with upper 90s across far eastern Colorado. The
surface trough remains in place over the forecast area with storm
expected to again develop along and east of the surface trough in
the area of greater moisture and instability during the afternoon.
Scattered thunderstorms will again move across mainly the eastern
sections of the forecast area through the evening hours.

.LONG TERM...(Thursday through Tuesday)
Issued at 202 AM MDT Wed Jun 21 2017

An amplified pattern begins to take shape on Saturday as a ridge
approaches the western coast of the US. Low pressure over the Hudson
Bay region will keep a broad trough in place across the northern and
eastern US as this ridge approaches. As this happens, northwest flow
aloft will usher in much cooler air across the Tri-State region for
the weekend with afternoon highs only reaching the upper 60s to
lower 70s. Lows will fall into the upper 40s to lower 50s. As the
pattern continues to amplify on Saturday night into Sunday, a
shortwave will push across the CWA and increase PoPs across the
region. The post frontal environment will not support widespread
thunderstorm development; however, a few isolated weak thunderstorms
cannot be ruled out. This activity will end from northwest to
southeast through the afternoon. We begin to experience return flow
on Monday as winds shift around to the south and southeast,
increasing moisture levels as we head through the afternoon.

The ridge and trough will slide eastward on Monday, allowing
temperatures to rebound into the lower 80s on Monday then back into
the upper 80s to near 90 degrees on Tuesday. Instability will begin
to increase as we head into Tuesday; however, the ridge and
associated subsidence should be enough to keep thunderstorm chances
to a minimum. If thunderstorms are able to form, it is worth noting
that the environment will be favorable for isolated severe storms.

Pattern amplification will diminish as we head into Tuesday and
Wednesday as the low weakens and the ridge flattens a bit.
Temperatures will reflect the diminishing effects of the low with
afternoon highs once more climbing into the middle 90s on Wednesday.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1136 PM MDT Tue Jun 20 2017

VFR conditions expected for the TAFs. Showers will continue to
move east toward the sites. The broken line of storms should last
long enough to move over KGLD based on radar trends. Have less
confidence the storms will hold together for KMCK since it is
further east. Otherwise low level wind shear at KMCK will continue
for a few hours then end as the low level jet shifts east. Winds
will turn from the south to the north for both sites as a surface
trough moves through Wednesday.




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