Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 270527

Area Forecast Discussion
National Weather Service Goodland KS
1127 PM MDT TUE JUL 26 2016

Issued at 751 PM MDT Tue Jul 26 2016

Fairly continuous squall line has developed across central portion
of the cwa with large organized cold pool in place across the
area. Temperatures cooled all the way down to expected lows
tonight as rain cooled airmass down to wet bulb temp. Will monitor
impact of cold pool for potential aviation type impacts should
this cool air not modify at all in the next hour or so.

For thunder chances...storms forming a bit farther north than
originally expected...but given instability and inhibition
profiles expect a southeasterly overall motion as storms may favor
a path of least resistance. Another concern will be large area of
deep moist convection occurring across northern nebraska. This
continues to dive to the south with at least a few models bringing
area into eastern zones as a mcs overnight. Although there is a
fairly weak elevated cap tonight...310 K isentropic surface per
RAP indicates a fairly weak pressure gradient across the area that
is somewhat disorganized and condensation pressure deficits around
potential instability of > 50mb. While I cant rule out or ignore
some of data bringing storms into MCK area overnight am going to
keep pops on low side for the moment as it appears to be a low
likelihood event.

UPDATE Issued at 434 PM MDT Tue Jul 26 2016

Primary forecast concern in the near term will be evolution of
small convective complex now entering the northwestern CWA. Fairly
large outflow boundary accelerating from this area and with
moist...unstable and weakly capped airmass in place see no reason
that storms wont continue to move east through the next few hours
at least. Some disagreement between CAM HRRR and RAP with respect
to evolution of storms. HRRR brings fairly large swath of storms
across the entire area...while RAP tends to favor storms building
to the south into instability axis which limits overall easterly
movement into Kansas. Both solutions seem viable and at this time
have chosen to increase PoPs and shift things as far east as Colby
through the early evening. Confidence definitely decreases with
time however so outside of portions of eastern Colorado cannot
ramp up probabilities too much.


.SHORT TERM...(This evening through Wednesday)
Issued at 144 PM MDT Tue Jul 26 2016

the short term forecast focus is on the possibility of
thunderstorms tonight and initiating again on Wednesday

The upper pattern increases in amplitude as the upper ridge
builds over the west and an upper trough deepens over the
Mississippi valley region in response. Upper flow over the
forecast area will turn from west to northwesterly and bring a
series of short wave troughs across the central high plains region
over the next few days. The first significant short wave trough
will move across the forecast area around midnight and the second
one will move through around 03Z Wednesday evening.

Storms developing over the palmer ridge and along the front range
of Colorado this afternoon will continue to develop and move east
over the plains through the remainder of the afternoon and early
evening. As these storms move east and approach the eastern
Colorado border, expect storms to dissipate as they continue east
overnight. Another area of storms is expected to develop over the
Dakotas and Nebraska, which will stay mostly north of the forecast
area as the upper short wave trough tracks across the northern and
central plains overnight. Some of the convective activity may
make it into southern Nebraska after midnight.

The scenario repeats on Wednesday, but appears to take a further
south track. This will expose a larger portion of the forecast
area to the possibility of thunderstorms. Also expect the earlier
timing of the short wave trough aloft to assist in thunderstorms
development earlier in the day. Have therefore started an increase
in thunderstorm coverage during the afternoon hours over much of
the forecast area.

.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 06Z TAFS through 06Z Wednesday night)
Issued at 1122 PM MDT Tue Jul 26 2016

Next aviation concern will be large cluster of storms diving south
across Nebraska. This significant MCS has been creating a large
area of wind gusts around 50kts...but should remain to the east of
MCK. May see a brief gust to 35 kts or so as outflow passes...but
do not expect MCS to move over terminal. While near term models
tend to keep storms east of area...not confident that MCK will not
see a period of thunderstorms before 09z as weak echoes developing
on a line to the north of MCK and will slowly move over terminal
soon. Could potentially see a period of ifr conditions in low
stratus or fog around 12z...but with large convective complex
forcing a large outflow boundary through area...confidence in
airmass too low to hold onto any prevailing sub vfr conditions.


.GLD Watches/Warnings/Advisories...


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