Goodland, Kansas

• Fog chances continue tonight and tomorrow morning.
• Chances for rain through Monday.
• Monday could bring some strong winds with gusts around 30-60 mph.

At 500 mb, we have a potent shortwave trough moving over the central High Plains. This is providing some light to moderate forcing, allowing showers to occur along and east of U.S. 83 early this afternoon. West of U.S. 83, there is a small amount of forcing, allowing some drizzle to fall. The shortwave is forecast to be exiting the CWA to the northeast over the next few hours, taking with it any lingering rain.

Also this afternoon, a low-level lee low is forming in Colorado. This is leading to a roughly 30 kts 850 mb LLJ, which is mixing down to the surface in the form of 20-30 kts gusts. These gusts are forecast to weaken around sunset, but southeasterly winds will persist.

The stronger winds and the showers are working to keep fog from becoming dense this afternoon. Fog is expected to lift a bit more over the next few hours, but return tonight. As it stands, there is 90% confidence that widespread fog will reduce visibilities down to 1-3 miles again by Sunday morning. There is also 70% confidence that areas along and west of a line from Tribune, KS to McCook, NE will see at least patchy dense fog, reducing visibility to 1/4 mile or less. The threat of more dry, southerly winds is hold back the issuance of a Dense Fog Advisory. Due to less favorable winds Sunday night and onward, tonight may be our last night of widespread fog.

Temperatures over the next 18 hours are forecast to change less than 15 degrees for any given location. Highs will be capped in the 50s to low 60s while lows will only cool into the 40s to mid 50s.

At 500 mb Sunday, there is a broad, but fairly strong, low moving onto the U.S. west coast as a weak ridge builds in over the Great Plains. Down at 850 mb, the lee low in Colorado stays pretty stationary during the day, but overnight it ejects to the northeast. This will lead to strong south-southeasterly winds Sunday afternoon and evening. We expect to see sustained winds around 15-20 kts with gusts of 30-45 kts, the strongest of which look to be along and west of KS 27. Timing for the strongest winds is forecast to be between 21-06Z, as supported by the HREF and REFS.

We should get a bit of a reprieve from the winds for a few hours Monday morning. However, if the nocturnal inversion does not set up or the surface pressure changes can overcome the inversion, these gusts will persist throughout the early morning hours Monday and spread east, across the rest of the CWA. There is a 40% chance that the gusts persist throughout the early morning. Either way, we should see a ~3 hour weakening in the winds Monday morning ahead of the cold front from this incoming system.

Monday morning, the 500 mb low driving this incoming system will be coming over the Rockies and still be pretty broad. As the system moves over the High Plains throughout the day, guidance is showing this system remain as a large open trough or two separate lows acting as a large trough. There is also a hint of a shortwave ridge near the CWA, which supports the two low theory. Down at 850 mb, by 12Z Monday, the low from the night before will already be in South Dakota. Around the same time, another 850 mb Colorado lee low could be forming, reinforcing the cold front that will be entering the CWA Monday morning. This second 850 mb low will be the primary factor determining how strong our winds are Monday behind the cold front.

Trailing the cold front we expect strong northwesterly winds. The closer the southern 850 mb low is to the CWA, the stronger the winds will be Monday. The favored path of the low, which has 60% forecaster confidence of occurring, is near the OK panhandle. This would produce widespread 30-45 kts gusts and isolated gusts up to 50-55 kts. There is a 30% chance the low`s path shifts north, in which case widespread 35-55 kts gusts and isolated gusts up to 65 kts would be possible. In either case, the strongest winds will be northwest of a line from Tribune, KS to McCook, NE and occur Monday afternoon and evening, between 18-06Z. Potential for blowing dust is less than 2% due to weak lapse rates and recent moisture.

Bottom line for the wind, widespread gusts over 50 kts have a 25-30% chance of occurring; widespread gusts up to 45 kts with isolated gusts up to 55 kts has a 55% chance of occurring; blowing dust is not expected to pose a threat.

Regarding precipitation, there is a 20% chance that light rain will be off and on across the area starting late Sunday morning and lasting through Monday evening, with a brief break early Monday morning. The first good chance for rain will be Monday 6-9Z east of KS 25 as a pre-frontal shortwave trough forms and pushes eastward. The second main chance will be with the cold front Monday afternoon as it sweeps across the entire CWA. Both of these precipitation focuses have a 70% chance of having some embedded storms. There is a 5% chance the storms with the cold front could produce some small hail and help mix down some stronger winds.

Finally, temperatures. Sunday is forecast to remain in the 60s, slightly warmer thanks to the stronger southerly flow. Monday can expect highs to be in the 50s in the northwestern CWA, where the cold front hits early, and up to 70 in Graham county where sunshine and southerly winds will be present. Overnight Sunday will remain fairly stable, likely only cooling into the 50s, but Monday night will be getting cooler. The persistent cloud cover and northwesterly winds will be duking it out and will likely cool temperatures into the 40s, but areas near the Tri-State border may cool into the upper 30s.

Next week starting on Tuesday and through Friday, we are forecast to be in a revolving upper-level trough and ridge pattern over the area. On Tuesday, it is expected that the trough system from the short-term period will slide east, bringing in a cold front, and putting us into northwesterly flow aloft as a de-amplifying ridge follows in from the souther Rockies on Wednesday. Once the ridge completely de-amplifies and flattens out over us, it would likely put us into zonal flow on Thursday. After this, a possible additional ridge could form in to the south and amplify to the north on Friday. With this being said, there is some marginal spread of uncertainty within the overall evolution of the pattern. While zonal flow is favored, GEFS ensemble spread shows some variability of the small trough on Thursday that could lead into slightly northwesterly flow before the ridge arrives Friday. There is low confidence (30%) that upper-level northwesterly flow will occur earlier on Thursday.

Afternoon temperatures for this long-term period continue to be fairly consistent with highs forecast to be in the 50s. However on Wednesday and onward, near freezing morning temperatures are expected to occur in the Tri-State border area. With the spread of the overall pattern later in the week, there is low confidence (20%) that temperatures could drop a few degrees into below freezing over the entire County Warning Area (CWA) if the pattern becomes northwesterly. Otherwise, morning lows will likely be in the 30s and slightly above freezing.

On Tuesday, showers and strong winds are expected to end once the initial trough system passes by. Showers are likely to exit out of the area before the mid afternoon hours with winds from the northwest decreasing from 30 mph to 10 mph. For the rest of the period, we can expect the winds to be calm and shift a couple of times with the changing pattern. Clouds should remain relatively low before possibly building back up on Friday.

MVFR conditions are expected to dominate, with occasional drops to IFR/LIFR, this afternoon and early evening for KGLD and KMCK. Southeasterly gusts around 20-30 kts are expected across the region this afternoon, as well as showers that may impact KMCK. We are expecting IFR conditions to return overnight, potentially nearing airport minimums yet again. Sunday, late morning, winds are forecast to be picking up with improving flight categories into the afternoon hours.

KGLD amendments will be excluding ceiling and sky coverage updates until the ceilometer has been returned to service. Technicians are currently investigating the issue.

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