Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 261832

Area Forecast Discussion
National Weather Service Goodland KS
1232 PM MDT TUE JUL 26 2016

Issued at 543 AM MDT Tue Jul 26 2016

Fog expanding not only outside of previously expected forecast
area but also any model output. Based on the trends of the
observations and satellite have expanded the areas of fog and
increased sky cover.


.SHORT TERM...(Today through Thursday night)
Issued at 403 AM MDT Tue Jul 26 2016

Main forecast issue remains thunderstorm chances. Satellite showing
an amplified pattern over the Pacific. This transitions to a flat
ridge over the southern half of the country with progressive flow
over the northern half.

At jet level...models started out fine. At mid levels...The Gfs and
Canadian were doing a little better than the other output. The Sref
and Ecmwf were doing the best on the surface wind and pressure
field. The Nam/Gfs/Canadian were doing the best on the low level
thermal field.

Today/tonight...Clouds from overnight convection have thinned
considerably and have allowed some fog and stratus to develop to the
south of our area. High resolution output is catching this nicely
and made adjustments to the fog and sky grids I inherited.

There may be jet lift over the western and northern areas during the
night. Late in the day a shortwave trough approaches the western
portion of the area. Earlier forecast had chances much further east
earlier in the day. It looks like now it will start later so pulled
that chance further west.

Again shortwave details having a hard time being resolved.
Considering where the shortwave is coming from would believe that
most of the area could see a chance of storms and the convective
allowing models showing a number of different scenarios/locations
getting hit would tend to bear that out. At this time will have the
highest chance in the north and northeast since that is where most
of the output has the qpf, and that is where the best lift is at,
especially at jet level. However, the tendency in this flow pattern
has been to underdo the amount of convection that rolls off the
higher terrain to our west.

Am thinking outflow from convection to our north and northeast will
create some fog and so inserted that into the forecast.

Wednesday/Wednesday night...At this time think fog will end by late
in the morning. There may be a left front quadrant affect the
northwest portion of the area during the afternoon and evening.
Numerous shortwave troughs moving through and models having a hard
time resolving those shortwave details. What makes even harder to
decipher is that models make it even worse by going nuts with
convective feedback.

Also models having a difficult time in deciding where to put the
front early on. They do look like they bring the front through the
area during the night. Overall would believe in a northwest flow
scenario the area should have a good shot at seeing thunderstorms
move across the area but above problems raise the uncertainty level.
At this time the northeast half appears to have the best chance of
storms during the afternoon and night. However, uncertainty is
rather high.

On a sidenote, considering that most of the output is showing a
large thunderstorm complex moving across to the north and northeast
of our area, a rather significant outflow boundary could roll
through the area, and throw a major wrench into the high temperature
forecast. Will tend toward the cooler guidance.

Thursday/Thursday night...At this time there looks to be lingering
thunderstorms in the east in the morning. There may be a left
front quadrant affecting the northeast half of the area during the
afternoon and evening. Same problem this period as previous two
days in models having difficulty in resolving shortwave
details/suffering from convective feedback issues. However, at
this time it looks like a rather strong shortwave appears to move
through the area in the afternoon and nighttime hours. Considering
the jet lift involved, ended up raising pops, mainly for the
night. With the front having moved through and area in a post
frontal regime, went cooler on the high temperatures.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 1232 PM MDT Tue Jul 26 2016

High pressure will be in place over the southwestern U.S. on
Thursday with subtle troughing to the east. A relatively potent
shortwave trough and associated theta-e boundary will pivot down
from the northwest, across the CWA late on Thursday. Good forcing
combined with CAPE in the 1000 to 2000 J/kg range, and deep layer
shear of near 50 kts will allow for thunderstorms to become severe
during the late afternoon and early evening. There is some
disagreement regarding the longevity of the convective activity with
the GFS ending storm potential before midnight and the ECMWF hanging
on through the night and into Friday morning.

Another shortwave will slide across the region Friday afternoon and
give us another chance of thunderstorms. Instability will be good
once more; however, deep layer shear will be disconnected to the
north and upper level support a bit weaker thus strength and
coverage is expected to be less than Thursday`s activity.

The southwestern ridge slides east as we head into Saturday and
Sunday, drying thins out across the Plains and allowing temperatures
to rise above normal. Only slight PoP chances are in the forecast
mainly during the late afternoon/early evening. Temperatures will
rise into the middle 90s on Sunday with upper 90s possible as we
head into Monday and Tuesday.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1149 AM MDT Tue Jul 26 2016

VFR conditions are anticipated through the TAF period at MCK and
GLD. There is a chance of thunderstorms at MCK between 06Z and
09Z as scattered thunderstorms are expected to develop and track
across southwest Nebraska. That possibility has been included in
the MCK TAF as a PROB30 group. That may be updated to include
storms as a prevailing group if thunderstorms develop across
southwest Nebraska and have a trajectories that would bring them
over the MCK site, or they may be removed in a later update if it
appears the trajectory of discrete storms will not be over MCK.


.GLD Watches/Warnings/Advisories...


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