935
FXUS63 KGLD 292346
AFDGLD

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

.KEY MESSAGES...

- Low confidence with regard to 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 /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 545 PM MDT Sat Jun 29 2024

GLD: VFR conditions will prevail this evening/overnight. MVFR
ceilings are anticipated to rapidly develop around or shortly
after sunrise (~12-14Z). Deterioration to IFR is likely
thereafter, during the mid-late morning. While some improvement
to MVFR is expected during the afternoon, ceilings may
deteriorate to IFR-LIFR within a few hours after sunset Sunday
evening. Easterly winds at 10-20 knots (this afternoon) will
gradually veer to the SE (overnight) and SSE (Sunday morning)..
increasing to 15-25 knots during the afternoon.

MCK: VFR conditions will prevail this evening/overnight.. and
through much (or all) of Sunday morning. Borderline VFR-MVFR
ceilings (~2500-3500 ft AGL) are anticipated to develop by early
afternoon (~16-19Z) and persist throughout the day. Ceilings
may deteriorate to low-end MVFR or IFR a few hours after sunset
Sunday evening. Easterly winds at 10-15 knots (this aft-eve)
will gradually veer to the SE (overnight) and SSE (Sunday
afternoon).. increasing to 15-20 knots by mid-late afternoon.

&&

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

&&

$$

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