261
FXUS63 KGLD 201129
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
529 AM MDT Mon May 20 2024

.KEY MESSAGES...

- Enhanced Risk for severe storms this evening from Yuma County
  east along the Kansas and Nebraska border area. A Slight to
  Marginal Risk elsewhere. In the Enhanced Risk area, supercells
  capable of producing large to very large hail, damaging winds
  and tornadoes will be possible, with the risks elsewhere being
  large hail and damaging winds. Locally heavy rainfall and
  flash flooding will be possible in the Enhanced Risk area,
  mainly in southwest Nebraska. The severe risk will continue
  well into the overnight hours.

- Patchy frost possible in northeast Colorado late Tuesday night
  and early Wednesday morning.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 220 AM MDT Mon May 20 2024

Cold front is making its way through northeast Colorado early
this morning and will continue to slowly makes its way through
the forecast area today. Initially winds will be northwest, but
by this afternoon will start to see them turn northeast and by
late this afternoon moist, easterly upslope winds will be in
place across a majority of the forecast area. A shortwave trough
embedded in the southwesterly flow aloft will move into eastern
Colorado late this afternoon and across the forecast area
tonight, providing synoptic scale lift for convection. Storms
are forecast to enter the northwest corner of the area, Yuma
County, by around 00z, in a weak to moderately unstable
environment of 1000-2000 j/kg, and deep layer shear values of
around 50 kts. CAMs strongly suggest supercells will be possible
as they move east along the Kansas and Nebraska border area this
evening in multiple rounds. Best tornadic environment will
probably be in the early evening when a surface based supercell
is possible, but with increasing CIN as they track east storms
will more likely become elevated and be capable of producing
large to very large hail as well as damaging winds. The severe
risk may extend well into the overnight hours with another
shortwave trough moving through. In addition to the severe risk,
heavy rain will be possible, especially across southwest
Nebraska where higher percentile QPF shows 1-2 inches possible.
Since heavy rain fell in Hitchcock/Red Willow counties last
night and Sunday morning, decided on a Flood Watch since those
counties are already seeing nearly saturated conditions and will
be more susceptible to flooding with the additional heavy rain.

Rain will continue into Tuesday morning for areas north of
Interstate 70, but more stratiform with stable conditions and
surface winds turning northwest as the front surges south again.
This should allow some afternoon sun and temperatures to warm
into the 60s and 70s. Another shortwave trough comes out of
Colorado Tuesday night with another round of showers and
isolated thunderstorms. Instability is very weak and no severe
storms are anticipated on Tuesday. Additional QPF amounts are
generally between a tenth and a quarter of an inch with this
system. Precipitation winds down overnight but clouds may
persist. Depending on the amount of clearing that occurs, some
patchy frost will be possible in northeast Colorado with lows in
the mid to upper 30s.

On Wednesday will see zonal flow aloft with dry conditions
during the day and high temperatures in the low to mid 70s.
Another shortwave moves across Wednesday night with scattered
showers and isolated thunderstorms, but once again instability
is weak and no severe storms are expected. Rainfall amounts
Wednesday night are currently forecast to be less than a tenth
of an inch. Low temperatures will be in the mid 40s to lower
50s.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Issued at 133 AM MDT Mon May 20 2024

An active weather pattern continues into the long term period as a
series of shortwaves move through the region, providing additional
chances (generally around 20-30%) for showers and storms.

At the start of the long term period, an approaching shortwave
trough is lending to southwesterly flow aloft as an upper low is
centered near the borders of ID/WY/MT. A surface low is forecast in
the lee of the Rockies by Thursday afternoon-evening with model
guidance suggesting convection developing out ahead of it. Friday
will again see chances for showers and storms as another shortwave
progresses through the flow during the afternoon-evening. Lesser
confidence as we head into the weekend; however, guidance keeps
shower/storm chances with a wave moving through in the Saturday-
Sunday timeframe. As mentioned previously, better moisture and
instability is forecast to reside across eastern portions of the
area during much of the period.

Regarding temperatures, highs are forecast in the low to middle 80s
for Thursday, cooler in the 70s for Friday, followed by a mix of
middle 70s to low-middle 80s through the remainder of the long term.
For low temperatures, expecting generally middle 40s to low-middle
50s.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 526 AM MDT Mon May 20 2024

Low clouds and patchy fog will give way to partly cloudy skies
and VFR conditions by late this morning or early this afternoon
at both KGLD and KMCK. This evening, scattered showers and
thunderstorms will develop across the region. Best chances for
impacts will be at KMCK from mid to late evening and into the
overnight hours. Chances are slightly lower at KGLD. Stronger
storms will be capable of producing large hail and damaging wind
gusts.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...Flood Watch from this evening through Tuesday morning for
     NEZ080-081.

&&

$$

SHORT TERM...JN
LONG TERM...CC
AVIATION...024