Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 241734
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1134 AM MDT Mon Jul 24 2017

.UPDATE...
Issued at 1055 AM MDT Mon Jul 24 2017

Lee surface trough over Colorado continues to support a southerly
wind flow across the forecast area with wind gusts of 20-25 kts
possible this afternoon. Temperatures are on track to climb into
the lower and middle 90s this afternoon. A few thunderstorms may
develop this afternoon along the Colorado lee trough but are not
expected to affect the forecast area given the weak southwesterly winds
aloft. Better chances for thunderstorms will exist later Tuesday
afternoon into the evening as a weak mid-level trough initiates
thunderstorms in Colorado which will then move into the forecast
area during the evening.

&&

.SHORT TERM...(Today through Wednesday night)
Issued at 258 AM MDT Mon Jul 24 2017

Large scale ridge remains in place across the southwest US, with
mean flow shifted further north and northeast from our CWA. A large
area of mid-upper level dry air and subsidence is in place early
this morning over KS.

Today-Tonight: Lee trough begins to deepen today and southerly flow
will bring both breezy conditions and WAA. Instability should
increase along CO state line. A dry air mass and strong CAP will
likely limit potential for convection developing locally. Weak
forcing associated with possible 50 kt mid level jet streak WY/CO
border is advertised to possibly support activity developing further
west, but mean wind wouldn`t support this making this into our CWA
this afternoon/evening. Guidance is keeping our CWA dry with any
activity forming in CO remaining NW of our CWA, supporting these
trends. Temperatures should be similar to Sun if not a little warmer
and I made a slight upward adjustment to account for increase in WAA.

Tuesday-Wednesday night: The ridge begins to flatten as a trough
moves along Canadian border. This results in stronger lee trough
development (hot temperatures and windier conditions). This shift in
pattern aloft also allows for the monsoonal plume to spread back
into the Central High Plains, and a more favorable storm
track/increasing forcing. A cold front will be approaching the
region and eventually moves through our CWA Wednesday with a
downward trend in temps Wed/Wed night. Anomalously high PWATs will
return with values in excess of 1.5" likely (possibly near 2"),
raising the concern for localized flash flooding depending on storm
motion/coverage.

Initially models are showing showers/thunderstorms developing to
the west-northwest Tuesday afternoon and then spreading
east/southeast into unstable air mass over our CWA. Shear will not
be great, but there could be enough instabilty for isolated severe
thunderstorms to develop. Guidance is showing stronger precip signal
Tuesday evening and I increased PoPs accordingly. Forcing is less
organized Wed-Wed night, and I stayed in line with consensus on
possible coverage (capped in chance category). Instabilty will
decrease rapidly in post frontal air mass, so weaker thunderstorms
and maybe just showers would be favored if/where activity develops.

.LONG TERM...(Tuesday through Sunday)
Issued at 208 AM MDT Mon Jul 24 2017

In the extended period the models are showing the upper level ridge
amplifying over the western U.S. This will produce an strong
northwesterly flow over the region. Towards the end of the period
the models differ significantly. With the ECMWF and NAVGEN maintain
the northwesterly flow while the GFS shows a sharper ridge axis
creating a north-northeasterly upper level flow over the region.

Regardless of how the upper level flow turns out towards the end of
the period, look for shortwave troughs to move within the flow
pattern and produce chance of showers and thunderstorms each
afternoon.

Temperatures look to be slightly below normal for the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1123 AM MDT Mon Jul 24 2017

For KGLD and KMCK...VFR conditions expected through the period.
Strengthening leeside trough will make for gusty, southerly winds
this afternoon. Should see winds relax after sundown at both
terminals with loss of daytime heating. Low level wind shear for
KMCK after midnight until sunrise. Winds pick back up for both
terminals tomorrow morning.

&&

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

$$

UPDATE...DLF
SHORT TERM...DR
LONG TERM...BW
AVIATION...SME


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