Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 232319

Area Forecast Discussion
National Weather Service Goodland KS
519 PM MDT Mon Apr 23 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 257 PM MDT Mon Apr 23 2018

Main forecast concerns will be frontal passage tonight and
chance/phase of precipitation across the area through Tuesday.
At jet level...looked to start out fine. At mid levels...models were
pretty close with the Ecmwf and Canadian starting out the best.
Models were not too far apart on the low level thermal field with
the Nam doing a little better.

Strong cold approaching from the northwest. Currently over eastern
Wyoming. This front push into the western portion of the area in the
mid and late evening hours and through most of the area by late
tonight and south of the area by mid morning. Gradient and pressure
rises support windy conditions behind this front.

Left front quadrant moves across the area during the morning. By
late afternoon, the jet axis lies across the northern portion of the
area. Potent and compact upper is moving into Wyoming from Montana
at this time. This system still to the north and west of the area
late tonight and will push across the area during the day tomorrow.

Lift will begin with the front and then increase through the night.
The brunt of the mid and upper forcing will occur later tonight and
through morning tomorrow. Very strong baroclinic and mesocale
forcing to move across through this period. Progression of pops and
storm has slowed up a little. Elevated cape near zero to negative
theta-e lapse rates will be in place through the night. As a result
added isolated thunderstorms to the precipitation through the night.

For the phase, I ended up keeping it rain. However, it will be close
to becoming mixed in the far western portion late tonight and early
tomorrow morning. Theta-e lapse rates are a little higher with no
elevated Cape around. Will the showery mention through the day.
Because of the thick cloud cover through the day ongoing
precipitation and cold air advection, lowered high temperatures from
the previous forecast.

.LONG TERM...(Tuesday night through Monday)
Issued at 240 PM MDT Mon Apr 23 2018

H5 low pushes southeastward Tuesday night into Wednesday morning
with showers winding down from west to east. Lingering showers will
remain in the eastern portions of the area through mid morning.
Colder air will be ushered in from the north as we approach sunrise
on Wednesday, giving us cooler than average low temperatures across
the CWA.

Shortwave high pressure prevails from late Wednesday through Friday
with dry weather and warmer temperatures each day. H5 low pressure
approaches the region late Friday into Saturday as the ridge
retreats eastward. Surface flow turns southerly, allowing a long
fetch of moisture to advect into the region. CAPE values increase
significantly by midday Saturday using the GFS as guidance; however,
there is not much in the way of agreement between the global models
and thus confidence is low in this solution. If models come into
better agreement, I will have better confidence in the possibility
of thunderstorm development along a theta-e boundary Saturday
afternoon/evening. If this occurs, severe storms are possible,
especially along and west of HWY 25.

Confidence remains low going into Sunday, as the GFS develops
potentially severe thunderstorms along a theta-e/frontal boundary
Sunday afternoon. The ECMWF holds onto the ridge a bit longer, thus
inhibiting thunderstorm development.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 513 PM MDT Mon Apr 23 2018

VFR to MVFR conditions are forecast for the TAFs. Southeast winds
will be light ahead of the front. Behind the front north winds
will be light to breezy, with the wind speeds increasing after
12z. The best chance for rainfall will be from 8-16z, although the
rainfall may exit sooner than that. As the front moves through,
MVFR cloud deck will accompany it. The cloud deck will slowly
raise through the morning, with VFR cloud deck during the
afternoon. IFR cloud deck may occur around 12z for a few hours as
the front moves through. Will wait until the next TAF issuance to
place a mention in if one is needed.




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