Vernon, Colorado Weather Forecast Discussion

737
FXUS63 KGLD 160856
AFDGLD
Area Forecast Discussion
National Weather Service Goodland KS
256 AM MDT Tue Sep 16 2025
.KEY MESSAGES...
- 10-20% chance of patchy fog tonight into Tuesday morning.
- Afternoon and evening storms will return to the region on
  Tuesday and Wednesday. Severe weather possible Tuesday.
  Potential hazards include hail, wind, flooding and perhaps a
  landspout or two.
- Highs in the 70s are expected Wednesday through Friday.
&&
.SHORT TERM /THROUGH WEDNESDAY AFTERNOON/...
Issued at 252 AM MDT Tue Sep 16 2025
A surface low located along the Palmer Divide is leading to mid to
upper level cloud cover across western portions of the area.
Weak moisture advection is also ongoing across the region with
SSE winds in place. I do have some concern for fog development
along and west of a Yuma to Wichita county line as dew point
depressions are already 2 degrees or less across the area along
with winds less than 10 knots. There is some potential for
dense fog as well with surface to 1km mixing ratio difference
around 6-8 g/kg primarily across Yuma county. The one thing
that is hurting my confidence in fog is the cloud cover from the
low to the west as that is affecting the radiational cooling
potential across the area since the fog would more than likely
be radiational fog than advection fog. Will maintain patchy
wording in the forecast for now. A 500mb shortwave is also in
place just west of the forecast area which is creating some
light showers, so can`t completely rule out a smidgen of
rainfall for western Yuma county this morning.
For today, breezy winds are again forecast across the area with a 15-
20 knot 850mb wind field in place. A slightly stronger 700mb jet
around 30 knots is also forecast to develop through the day as well
which will lead to the potential for wind gusts of 30 to possibly 40
mph across the area. Cloud cover will be the big variable for today
which will determine how much mixing can occur which will dictate
how strong the winds get and also temperatures. Current thinking is
that cloud cover will hold strong for most of the day which will
limit how quickly we warm, however some breaks in the clouds are
likely during the afternoon hours which will quickly rise
temperatures where those occur at so have left temperatures in the
mid 80s with the exception being NW Yuma county where a continued
combo of cloud cover and post cold frontal air will be in place.
The most impactful part of the forecast looks to be the increasing
threat for showers and storms across the area starting as early as
2pm MT. The earlier development at this time appears to be more
conditional and would favor those along and east of a Hitchcock to
Logan county line. Some guidance indicates a weak dry line with some
forcing as the surface shifts a bit to the east; however the
uncertainty with this comes from the lack of upper level
support. Should any storms develop in this area large hail to
inches in diameter would be the primary threat. Should a storm
take a right mover motion which is stationary which would then
pose a localized flash flooding threat as PWATS are forecast
around 1.3. Should be fairly easy to tell if localized flooding
will be a concern as left mover motions are to the north around
25-30 knots.
The main show however looks to get started around 4-5pm MT with the
combination of the surface low, the arrival of upper level
support in the form of 500 and 700mb vorticity from a developing
mid level low pressure across Nebraska and the southward
advancement of a surface cold front. Storms look to initially
develop along a surface convergence boundary due to a pre
frontal trough which may support some landspout potential due to
the steep lapse rates in place and stronger convergence at the
surface. If more sun can me in place then surface vorticity will
also increase further helping landspouts to form. Based on
current forecast guidance positioning of this feature a
corridor from Dundy county down through western Cheyenne county
Colorado will be favored. As the upper level support arrives
additional storm development will begin to occur near the
Kansas/Colorado state line. Hail up to golf ball size will be
the main concern with any stronger updrafts or if updrafts can
be more discrete in nature. I do think storm coverage will
increase due to the amount of forcing during the late afternoon
hours and with straight line hodographs in place. Right mover
motion again is near stationary so localized flooding can`t be
ruled out. As the cold front begins to move to the SSE this
looks to lead to a cluster of storms with damaging winds to 70
mph and and very heavy rainfall the main threats this looks to
be from around 7pm through 12am MT and currently favors those
north of Interstate 70. A secondary wave off of the Rockies may
interact with this activity as well leading to continued heavy
rainfall as PWATS increase to around 1.6 inches which may then
lead to more flooding concerns especially for those that see
the most rainfall leading up to this. Corfidi vectors do
substantially slowdown to around 24 knots downshear and 5 knots
upshear which may lead to some training concerns. Should a
combination of training storms interact with right moving storms
then an isolated instance of 4-6+ inches of rain is not out of
the realm of possibility, especially along and north of Highway
36 on the Kansas side and into SW Nebraska. Rain chances will
then continue through the remainder of the night slower ending
north to south just after sunrise Wednesday as subsidence
begins to push in from the north. Will also need to keep an eye
on fog and stratus potential behind the rainfall Wednesday
morning.
Into Wednesday morning some additional showers are also possible as
additional vorticity maxes move through the area creating increasing
lift across Yuma county and finally further south into the
early afternoon. Not overly excited about thunderstorm and
lightning potential with this activity as the better forcing
looks to remain near the surface.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 121 PM MDT Mon Sep 15 2025
The active pattern will continue through the long-term.
Precipitation looks to cease Wednesday morning. An upper-level low
moves over the area Wednesday, leading to cloud cover and cooler
temperatures, likely in the low to mid 70s. Generally, temperatures
look to remain in the 70s until Friday when our next ridge will be
pushing into our area. Lows are forecast to cool into the 50s with
the eastern CWA potentially seeing upper 40s later in the week.
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1127 PM MDT Mon Sep 15 2025
VFR conditions are forecast to prevail into Tuesday afternoon,
before scattered thunderstorms approach the terminals. However,
00z CAMs have hinted there`s at least some potential for
nuisance fog or IFR stratus near and west of GLD where
HREF probabilities for each climb to around 20%; felt these
chances were low enough to not mention in the 06z TAFs, but
observation and model trends will be monitored closely overnight
in case a tempo group should become necessary.
Outside of thunderstorms, south-southeast winds will rise
sharply around lunchtime with gusts to 25-30 kt (possibly higher
at GLD) mid afternoon to early evening. Thunderstorms may
generate briefly higher winds, hail, and torrential rain which
could bring visibilities into the IFR category. The little
environmental shear supporting these storms suggests they will
lack organization, with storm evolution dictated by merging
outflows; this means nailing down timing is a challenge at each
airfield. Included a PROB30 group for the 4 hour period of
highest confidence, which seems to be roughly 00-04z based on
available highres guidance.
&&
.HYDROLOGY...
Issued at 121 PM MDT Mon Sep 15 2025
Over the past few days, the U.S. 34 corridor have received between
0.25 and 2.5 inches of rain. We have not received any reports of
flooding across this area over the past few days and Monday`s clear
skies will help to dry up the area, making it more resistant to
flooding. However, as mentioned in the discussion above, there is a
chance for training, efficient precipitation following a round of
potentially severe storms Tuesday evening into Wednesday morning. If
the training storms are able to form, our Nebraska counties could
see 1-2.5 inches of rain over a course of 6-12 hours with pockets up
to 4-5 inches. Confidence in these higher amounts is only around 10-
20%, but it`s a risk that shouldn`t be discounted. Current
confidence in nuisance flooding (water in fields, full ditches, low
water crossings with some flowing water) occurring in our Nebraska
counties is ~45%. Confidence in flash flooding in the same area is
about 20%.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...Trigg
LONG TERM...CA
AVIATION...Bumgardner
HYDROLOGY...CA

NWS GLD Office Area Forecast Discussion