Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 170137

Area Forecast Discussion
National Weather Service Goodland KS
737 PM MDT Sun Jul 16 2017

Issued at 730 PM MDT Sun Jul 16 2017

Adjusted areal extent and timing of rainfall tonight based on
latest near-term data. RAP model seemed to have a decent handle on
current storm activity and had done well last night. The
frontogenesis in the 600-500mb layer and lift in the 310K through
325K levels indicate the storm activity will develop near the
CO/KS border early this evening and be in a north-south line. This
lines up well with the 500mb vorticity that will be rotating
around the center of the closed upper level low. The storms will
move little this evening, so wherever the storms form, they will
linger there for awhile. Have good confidence in the
location/timing of storms this evening, however confidence is
lower for overnight. Models are split with the storms either
tracking more north-northeast or northeast. Regardless of the
track the storm activity will gradually decline overnight as 500mb
vorticity declines. Will hold off making significant adjustments
to the rainfall chances for overnight to see how storms
develop/move, and see if the data comes into better agreement.


.SHORT TERM...(This afternoon through Monday)
Issued at 204 PM MDT Sun Jul 16 2017

Plume of deep moisture continues to linger over our CWA (apparent
on WV imagery), with mid-upper low near CO border.

This afternoon-Tonight: Thunderstorm activity is already beginning
to redevelop along western edge of main instability/moisture axis
near the CO state line. Latest RAP analysis indicates SB CAPE in
excess of 2000 J/KG and supports ML CAPE increasing to this range
within the next few hours. Shear is very weak, so other than less
organized isolated stronger cells (marginal hail) main concern
continues to be hydro. MOdels show increasing forcing over our CWA
as a strong lobe of vorticity on back side of mid level
circulation rotates over our CWA this evening and overnight.
Result should be increasing coverage, though with CAPE decrease
during the evening hours, moderate to occasionally heavy showers
may be favored over thunderstorms. I adjusted PoPs/QPF with latest
short range consensus blends to match these trends.

Monday: Main mid-upper low should be northeast of our CWA, but
lingering forcing on back side of system may support continued
shower and thunderstorms chances in our northeast and east.
Moist/unstable air mass in the afternoon could support isolated
activity further west near building surface trough, but current
guidance is favoring our east with possible subsidence in our west.
Bulk effective shear should be near or just above 30kt, so with
better shear we may have a better chance for severe thunderstorms in
our far northeast than we have had over the past few days.

Regarding temperatures: As has been the case, cloud cover and
linger precip complicate overnight lows, with locations that
clear out dropping to near 60F (more likely west). Otherwise,
where precip lingers overnight lows may not drop much lower than
the upper 60s/near 70F. With mid-upper low exiting and surface
trough building in our west we should see WAA through the day
Monday. This will support highs in the 90s, with a few locations
possibly reaching the 95-98 range assuming good clearing/mixing.

.LONG TERM...(Monday night through Sunday)
Issued at 204 PM MDT Sun Jul 16 2017

Monday night-Tuesday: Shortwave transverses the area bringing a
chance of showers and storms Monday evening and overnight. Ridging
aloft begins to build as high height center will be over the area.
May see a few pop up showers over northern portions of the area
Tuesday afternoon. Highs will be above normal with most locales in
the upper 90s and low 100s.

Wednesday-Thursday: Upper level ridging dominates the weather
through the period. Models in good agreement that these two days
will be the hottest of the week. Heat indices will be near or above
105F for areas east of Highway 83. May see a few storms develop over
parts of our CO counties during the late afternoon to early evening
on Thursday.

Friday-Sunday: Models are not in particular good agreement for this
coming weekend. Upper level ridging begins to progress to the east
of the CWA on Friday. Zonal flow follows on Saturday. Looks as
though there will be a chance of rain each day. GFS is advertising a
similar setup as the one that has affected the CWA the past few
days, with an upper low meandering towards the area from CO on
Sunday bringing good chances of rain and plenty of cloud cover.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 519 PM MDT Sun Jul 16 2017

VFR conditions forecast for the TAFs. Main focus will be the
timing of storms that will move over KGLD this evening. Based on
how well the model data has performed the last two nights, am not
too confident with the exact timing of the rainfall for KGLD.
Based on latest data, am confident rainfall will be over the site
during the latter half of the evening, but confidence lowers in
regard to the begin/end of the rainfall. Any rain that moves
overhead will likely be moderate, possibly heavy. KMCK should have
rain move over the site in the overnight hours.




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