251
FXUS63 KGLD 161146
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
546 AM MDT Tue Jul 16 2024

.KEY MESSAGES...

- Severe chances during the late afternoon to overnight hours
  with wind the primary hazard, but also a few instances of
  marginally severe hail and flash flooding possible.

- Temperatures closer to normal beginning tomorrow and
  continuing through the weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 434 AM MDT Tue Jul 16 2024

On Tuesday an upper trough extending over the Plains from south of
the Hudson Bay in Canada and will flatten the upper ridge over the
Central Plains giving us more of a zonal flow aloft. Moisture will
continue trying to advect in from the Atlantic and NE Canada again
today while weak shortwaves move over the Rockies and Central High
Plains. This will provide another chance for showers and storms to
impact the entire area and continue through Thursday morning. SPC
has placed the entire area in a Slight Risk for today as large
clusters could develop over East-Central Colorado and Northwest
Kansas during the late afternoon/early evening to overnight hours. A
big question is whether or not the upper level divergence can help
provide some lift so that whatever develops can interact with the
500-2000 J/kg of CAPE over the area. Shear is also slightly better
today to promote more organized storms. The NAMnest seems to be more
of the high end/"worst case" as it has more isolated to scattered
convection developing out of Southern Nebraska into Northwest Kansas
during the late afternoon followed by a widespread cluster of storms
moving into the area from  East-Central Colorado and impacting those
generally south of the Nebraska border. Over the last few nights,
the 06Z run of the HRRR has seemed to handle the convection fairly
well, so we are trending more towards it today. The 06Z HRRR is also
the "best case" as we have limited convection over the area around
00Z with majority of the strong to severe storms occurring just
outside of our southern CWA border. Inverted-v soundings seen in
CAMs along and south of I-70 indicate damaging wind gusts and large
hail up to the size of quarters are the primary concerns; however,
the hail threat will decrease as we move in the evening and evolve
into more of a linear cluster. Heavy rain is also a concern with PWs
greater than 1" favorable for flash flooding should storms begin to
train over the same area or move slowly given the 15-20 kt storm
motions. Highs will be in the low to mid 90s with overnight lows in
the upper 50s to mid 60s.

On Wednesday the upper trough will push further south and amplify
the ridge over the Western CONUS placing the Tri-State area under NW
flow aloft. Some monsoonal moisture will interact with the moisture
stemming from the Atlantic to keep the rain and storm chances (up to
45%) continuing through the overnight hours where chances decrease
to around 15-20% over the central columns of counties. SPC has
placed those along and west of a Trenton to Leoti line into a
Marginal Risk for strong to damaging wind gusts associated with
isolated to scattered storms. High temperatures will be even cooler
thanks to the cloud cover with temperatures forecast to reach the
low to mid 80s. Overnight lows will be in the upper 50s to lower
60s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 227 AM MDT Tue Jul 16 2024

Little has changed from 24 hours ago. The long-term looks to be a
fairly active period. A 500mb high pressure system will be sitting
over the Four Corners area with a trough over the Great Lakes. This
will put us under generally northwesterly flow the period. There are
some weak ridges and troughs that will keep the flow "interesting."
GEFS is showing a trough moving south, over the Great Plains during
the weekend that may force the high to retrograde more into the
Great Basin area. This would also bring in a more northerly flow and
give upper level support for convection.

In the lower-levels, we look to start with southerly 850mb flow,
which will pull moisture from the SE CONUS and bring it into the
CWA. Friday night, the GFS, CMC-NH, ECMWF, and GEFS are all showing
a low moving across the Northern Plains and extending a cold front
down through the CWA. This front would likely be the best forcing
mechanism in the period and could fire numerous storms. Due to how
far out this event is, specific hazards are difficult to pinpoint,
however guidance is suggesting we could have a high precipitation
event. Some of the parameters supporting this include PWATS ranging
from 1.2-1.7 inches, low-levels becoming easily saturated, a
weak/moderately unstable column, and moderate shear. It would also
not be surprising if this system shifts to Saturday night if the
high pressure retrograde is slower than predicted.

The aforementioned low-level low pressure system looks to move in a
southeastern direction, which supports cooler temperatures with wrap
around moisture and northerly flow. This would work to increase non-
severe precipitation chances over the remainder weekend, but there
are a few reasons why this precipitation may not occur. For example,
we could get dry, southwesterly flow returning near the surface
which would cause more virga than precipitation.

On the very positive side, temperatures will be cooler! It looks
like the high temperatures will range from the upper 70s to lower
90s, with the warmest day being Friday. Overall, low temperatures
are stable, cooling into the mid 50s to mid 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 533 AM MDT Tue Jul 16 2024

KGLD...VFR conditions are expected through the period. Winds are
expected to be light at 5-10 kts and variable out of the north
to northeast through the mid afternoon. Beginning around 00-03Z,
scattered storms may develop and move within the vicinity of the
terminal. These storms would be capable of gusts up to 50 kts.

KMCK...VFR conditions are expected through the period. Winds
are expected to be light at 5-10 kts and variable out of the
north-northeast to northeast. After 00 Z, winds will become
easterly at 5-10 kts. There is low confidence in storms moving
over the terminal between 00-06Z tonight, so the mention has
been left out of the TAFs for now.

&&

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

&&

$$

SHORT TERM...KMK
LONG TERM...CA
AVIATION...KMK