Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 190844

Area Forecast Discussion
National Weather Service Goodland KS
244 AM MDT Wed Jul 19 2017

Issued at 1122 PM MDT Tue Jul 18 2017

Just completed another update to adjust winds and add fog to the
northern portion of the area through the rest of the night.

UPDATE Issued at 713 PM MDT Tue Jul 18 2017

Updated for the expiration of the heat advisory.

UPDATE Issued at 624 PM MDT Tue Jul 18 2017

Cluster of thunderstorms currently over the northwest corner of
the area. High resolution guidance having some difficulty in
capturing latest trends although they do cluster around the best
chance of thunderstorms over northern Yuma county. As a result of
the latest trends and best performing high resolution guidance, am
adjusting pops accordingly.


.SHORT TERM...(This afternoon through Wednesday)
Issued at 208 PM MDT Tue Jul 18 2017

Large scale ridge extents from the southwest US, across the Central
High Plains, and into the southern Mississippi River Valley. A plume
of monsoonal moisture is shown on WV imagery to be rotating through
the western extent of this ridge and into the Central Rockies.

This afternoon-tonight: A front stalled over the Nebraska Panhandle
may shift south slightly in response to a mid level shortwave
associated with monsoonal flow riding the northern part of the ridge.
This should remain north of our CWA, but the increased forcing may
combine with weak convergence along surface trough in our northwest
to kick off thunderstorm activity. CINh has already weakened in this
region and a shallow CU field has developed. RAP analysis support ML
CAPE in excess of 2000 J/KG and PWATs around 1-1.3" range. Shear is
less impressive, so once again localized heavy rain and pulse
thunderstorms are favored (hail/wind). Thunderstorm activity is
shown by high res guidance to drift to the southeast which takes it
away from better instability, but does raise the possibility for
showers/thunderstorms further south and east than originally
anticipated. I made adjustments to account for these trends.

Wednesday: Ridge shifts just a little further north and we should
see subsidence in place and a less favorable pattern for possible
afternoon thunderstorm development. Guidance is in line with this
shift in pattern, and keeps conditions dry over our CWA.

Regarding Temperatures/Heat Advisory: We have yet to reach
advisory criteria over most locations in advised area, but it is
getting close and a few locations are just now starting to reach.
There is an upward trend in temps in line with forecast, and Tds
are remaining high in our east. No changes planned as heat index
values 103-105 (a few higher) still appear likely across advised
area. Overnight lows remain mild, but heat indices should decrease
below 75 (may be close in our far east), so a decision was made
not to extend advisory overnight. Tds may be a little lower on
Wed, but temperatures will not be much different (upper 90s/lower
100s). Result should be 103-105 heat index values confined in our
north and east, and I issued another Heat Advisory for Wed
afternoon/early evening at favored locations. I am less confidence
further west and south.

.LONG TERM...(Saturday through Tuesday)
Issued at 243 AM MDT Wed Jul 19 2017

Saturday and Sunday: Nearly zonal pattern will be in place across
the central Plains with very weak upper flow out of the west to west
northwest. Weak high pressure will build across the western States
on Saturday, moving eastward as we head into Sunday. There will be
enough instability along a cold front to allow thunderstorms to
develop Saturday afternoon and evening, persisting into Sunday as
this front stalls and lingers in the region. High temperatures will
top out in the 90s on Saturday and the 80s on Sunday as the front
influences the area.

Monday and Tuesday: Remnant theta-e boundary will be in place,
serving as a focus for thunderstorm development as we head into the
day on Monday. A shortwave is expected to develop along the upstream
side of the eastward moving ridge, providing lift from southwest to
northeast across the CWA Monday afternoon and evening. There will be
a good chance of thunderstorms with this shortwave with the
possibility of a few strong to severe storms mainly confined to the
western half of the CWA given the current guidance. A slightly more
active pattern will continue on Tuesday and Wednesday as we will be
on the upstream side of the ridge axis, allowing occasional
shortwaves to traverse the region and increase thunderstorm chances
across the area. Moisture levels will remain relatively high as
monsoonal flow is expected to continue.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1122 PM MDT Tue Jul 18 2017

For Kgld, vfr conditions are expected through the period. Through
the rest the night the wind field will light and variable due to a
lot of outflow boundaries drifting across the area. During the
morning hours the winds are expected to shift to the south and
initially be around 10 knots. Near 18z, the south winds will
increase to near 17 knots with gusts to near 25 knots. Near sunset
those winds will lose their gustiness and remained sustained near
11 knots.

For Kmck, mvfr conditions due to fog are expected through the
early morning hours as a result of light winds and a moist low
level air mass. From 15z to the end of the period, vfr conditions
are expected. During the morning south winds will increase. Late
in the morning to the early afternoon those winds will increase to
near 15 knots with gusts to near 23 knots. Near sunset those winds
will lose their gustiness and remained sustained near 10 knots.


KS...Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening
     for KSZ002>004-015-016.

NE...Heat Advisory from noon MDT /1 PM CDT/ today to 7 PM MDT /8 PM
     CDT/ this evening for NEZ079>081.



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