Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 290752

Area Forecast Discussion
National Weather Service Goodland KS
152 AM MDT Mon May 29 2017

.SHORT TERM...(This afternoon through Monday)
Issued at 1134 AM MDT Sun May 28 2017

Latest upper air analysis shows a closed low over Southern Canada
extending south to the Northern Plains.  Within the northwest flow
over the Northern Plains were a couple subtle short wave troughs.
Under the southern short wave trough visible satellite shows a
developing line of cumulus clouds over Central Nebraska. At the
surface a weak cold front extends northwest to southeast over the
Northern Plains.

For the rest of the afternoon Red Willow, Norton and possibly
Hitchcock counties may have a chance for some isolated storms as a
short wave trough moves through. Most of any storm activity that
develops should be east of these counties.

Tonight the upper level short wave trough over North Dakota will
move south over the Tri-State Area along with the cold front.  There
will be enough lift and low dew point depressions above 700mb to
possibly generate some isolated showers as the front moves through,
mainly over the east half of the area.  Due to the cooler air mass
moving through, lows will be cooler than last night.

Monday morning there may be some isolated showers over the central
part of the area as lift increases over an axis of higher theta-e
values.  In the latter half of the afternoon thunderstorms will
begin to move in from the west as another short wave trough moves
southeast, with storm activity grazing the southwest quadrant of the
forecast area.

.LONG TERM...(Tuesday through Sunday)
Issued at 146 AM MDT Mon May 29 2017

Upper flow pattern will be somewhat split across the southern and
central High Plains on Thursday. A ridge of high pressure will be
positioned just west of the CWA with a deep trough moving onshore in
the Pacific Northwest. Subsidence under the ridge will keep things
dry across the CWA on Thursday; however, moisture levels will build
as south to southeast winds prevail through the day.

A dryline will set up on Friday, providing a focus for thunderstorm
development during the afternoon and evening. CAPE values will
approach the 1500 to 2000 J/Kg range; however, due to the lack of
shear both in the 0-1 km layer as well as the 0-6 km layer,
supercell development is not expected. The more likely mode will be
multi-cell cluster type storms capable of pulse type severe activity
to include hail and damaging wind gusts. Due to the proximity of the
dryline and theta-a boundary, we will need to monitor the potential
for landspout type tornadoes mainly during the late afternoon hours
as there could be just enough low level shear along these boundaries
to allow for brief spin-ups. Additionally, due to very weak upper
flow, storm motion will be quite slow and with PW values around
1.10 inch, we could see localized flash flooding potential.
Showers and thunderstorms could persist into the overnight hours
as the dryline retreats slightly through around midnight.

Global models significantly disagree about the flow pattern going
into Saturday. Generally, a shortwave ridge will begin to set up to
our west once more with weak shortwaves propagating down the leading
edge into the CWA. Slight thunderstorm chances will remain in the
forecast at this time; however, with the ridge being in very close
proximity and approaching from the west, there may be just enough
CIN to prevent anything more than an isolated thunderstorm or two.

For Sunday, another weak shortwave will push across the region as
the ridge slides eastward. Chance PoPs are in the forecast with
afternoon thunderstorms being possible from west to east. The
strength of the thunderstorm activity looks very uncertain at this
time as CAPE values will only be in the 500 to 1000 J/Kg range with
weak 0-6 km shear.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1134 PM MDT Sun May 28 2017

VFR conditions are expected through the TAF period at KGLD and
KMCK terminals. West to northwest winds will tend to remain below
10kt through the TAF period with high pressure persisting near
the region. There is enough NW flow aloft that light showers near
the terminals tonight or winds during the afternoon may increase
to the 12kt range with brief gusts.




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