955
FXUS63 KGLD 292022
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
222 PM MDT Sat Jun 29 2024

.KEY MESSAGES...

- Low confidence for strong to severe thunderstorm development
  tonight and Sunday night.

- Much cooler highs Sunday due to cloud cover all day.

- Hot weather returns Monday behind a warm front. However highs
  are not as hot.

- Chances for storms each day, mainly during the evening.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 216 PM MDT Sat Jun 29 2024

Latest upper air analysis shows nearly zonal flow over the central
Plains.  Pockets of higher water vapor were moving through this
flow, leading to cloud cover.  At the surface winds were breezy from
the northeast.  A surface high pressure was located over Wyoming.

For the rest of the afternoon the surface high pressure will slide
southeast across Nebraska, causing the winds to turn to the
southeast.  As the high pressure approaches winds will decline.

This evening a weaker upper level short wave trough will move over
the forecast area from the west.  The latest model runs have
slightly delayed the arrival of the upper level short wave trough.
(This is in line with the delayed trend in storm arrival of the last
few days.)

Models are now keeping the cold front well south of the forecast
area during the night.  However the low level jet will strength over
the front and into the forecast area.  This will provide low level
moisture advection ahead of the approaching upper level short wave
trough.  Both the NAM and RAP models are suggesting elevated
instability will be present with in this part of the forecast area.
In addition there does look to be a weak LLJ nose over the southern
part of the forecast area.  Am thinking scattered storms should form
ahead of the approaching upper level short wave trough around
midnight, then gradually spread east-northeast ahead of the short
wave trough.  Storms will be moving around 15 MPH, which may lead to
heavy rainfall given the precipitable water values of over an
inch in that part of the forecast area. The storm activity may
last well into Sunday morning.

At this time confidence for severe weather occurring over the
southern part of the forecast area is low (30%).  This is due to the
midlevel lapse rates being around 6C/km and deep layer shear being
25-30kts.  Strong thunderstorms seem more likely in this
environment.  If severe thunderstorms were to form, quarter size
hail would be the main threat.  The highest elevated instability
will be around midnight.  This threat area may shift north or south,
however the latest model run has shifted the elevated instability
south.

Meanwhile the continued moisture advection from the LLJ will bring
in low clouds from the south.  These will start from the CO/KS
border then gradually expand eastward through the overnight hours.
The surface high over Nebraska will also aid in advecting moisture
over the forecast area.

Sunday morning the upper level short wave trough will continue to
move across the southeast part of the forecast area.  Elevated
instability will continue to decline.  Storm activity should be
east of Graham County by noon, if not before.

Sunday afternoon an upper level short wave ridge will move in from
the west.  By this time the surface high pressure will be Central
Nebraska into Central Kansas.  Moisture advection will continue.
Soundings show atleast a broken, if not overcast cloud deck over the
forecast area through the day.  The exception will be East Central
CO where the moisture advection will be less, allowing the clouds to
break up during the afternoon.  Lowered highs a few more degrees for
the afternoon, mainly east of CO.  The 25th percentile high
temperature forecast is in the low/mid 70s for this part of the
forecast area.  Based on this the current forecast seems
representative.

Sunday night another upper level short wave trough will move in from
the west.  By this time the ridge has shifted more to the west,
pushing the upper level flow slightly more to the north.  During the
evening there may be some low level convergence from the LLJ over
the northwest part of the forecast area as the short wave trough
moves through.  This convergence then shifts to the northern part of
the forecast area, moving with the upper level short wave trough.
Models show deep layer shear of 40 kts and midlevel lapse rates
around 7C/km. The current data supports the potential for
storms to become severe given the elevated instability could
occur. However, the elevated instability is highly dependent on
how warm will 800- 700mb layer be and how high will the dew
points be in that layer. The HREF has not strong storms in the
forecast area at this point. For now this bears watching as
strong to severe elevated thunderstorms could occur. However
confidence is low (20%) for them to occur given how much could
change with the small details regarding the low level
temperature and moisture advection.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 216 PM MDT Sat Jun 29 2024

Monday the front will move back through as a warm front.  Models
have shifted the upper level ridge slightly more to the east.  This
move has also shifted where the dome of hottest temperatures will
be, resulting in highs not being as hot for the forecast area.  Heat
index values are now around 100F instead of 105F.  During the latter
part of the afternoon a stronger upper level short wave trough will
move into the forecast area from the west.  Midlevel lapse rates
sharply decline behind the trough, suggesting there maybe a narrow
window for strong to severe thunderstorms to form.

Monday night the storm activity will move east across the forecast
area.  A band of frontogenesis accompanies the trough across the
forecast area, mainly over the northern half of the forecast area.
As such, have the best chances for rainfall there.

Tuesday through Saturday evening chances for rainfall each day are
forecast as upper level short wave troughs move over the forecast
area.  The upper level ridge will shift west and become centered
over the Desert Southwest.  This will shift the storm track to be
from the northwest over the forecast area.  Rainfall chances during
this timeframe seem high, which may be due to the monsoonal moisture
moving over the forecast area. Wouldn`t be surprised if the rainfall
chances end up lowering as we move through the week.

Due to the ridge ridge shifting west of the forecast area, highs
will not be as hot.  The coolest temperatures are Friday when a
stronger upper level short wave trough rounds the ridge and brings a
cold front with it.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1138 AM MDT Sat Jun 29 2024

VFR to IR conditions forecast for the TAFs. Breezy northeast
winds will continue to turn to the southeast through the day as
the surface high pressure slides southeast across Nebraska.
After 12z Sunday MVFR to IFR ceilings will move in from the
south over KGLD. KMCK should be far enough east to not have
these ceilings move over until after 18z.

Am expecting thunderstorm activity tonight to remain south of
the TAF sites.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.

&&

$$

SHORT TERM...JTL
LONG TERM...JTL
AVIATION...JTL