textproduct: Goodland

KEY MESSAGES

- Air temperatures nearing 100-105F are forecast through Tuesday. Heat indices may approach/briefly meet 105F along and east of Highway 83 in Kansas.

- Repeat of yesterday with the storm activity this afternoon/evening; straight- line wind gusts being the primary threat.

- Storm chances continue daily the next few days.

SHORT TERM /THROUGH TUESDAY/

Issued at 1139 AM MDT Mon Aug 10 2026

Upper air analysis shows the ridge over the Four Corners Region becoming more flat than yesterday. Water vapor imagery shows a corridor of moisture extending west from the forecast area toward the mountains; cloud cover is increasing in this corridor.

This afternoon the cloud cover should persist into the mid afternoon before clearing some. There may be a couple hour clearing in the clouds before the next round of storms move in from the west. The lingering cloud cover may allow temperatures to be a few degrees cooler than what is forecast. Meanwhile the line of storms should move into the forecast area around 5 PM. The environment looks very similar to yesterday, high cloud bases low level jet (LLJ) nose forming to the south late afternoon, and an upper level short wave trough moving in this evening. Dew points continue to be higher going north in the forecast area, and deep layer shear slightly increases northward too. Main threat will be wind gusts up to 70 MPH with any storms.

This evening the upper level short wave trough continues moving eastward across the forecast area, filling as it exits CO. Meanwhile the LLJ nose will move northward. This added source for convergence should cause storm coverage to increase, or atleast remain the same as the storm wave trough fills. A secondary effect will be the LLJ nose limiting how far east the storm activity will go. With the short wave trough filling, am not expecting storm activity to continue much past the LLJ nose during the evening. Where the LLJ nose sets up will determine the eastward extent of the storm activity. Storm activity should end before midnight.

There may be a rather narrow window for large hail to occur this evening. As the storm activity moves east the deep layer shear will weaken as the winds decline with the ridge strengthening. The large hail threat should decline as the deep layer shear weakens. Am thinking the hail should be quarter size at largest.

Model ensembles focus the severe wind threat over CO, with the wind threat declining as storms exit CO. This seems reasonable given the upper level short wave trough weakening as it moves eastward with the ridge strengthening. The high end value for wind gusts is 70 MPH, with the mean value being around 40 MPH

Models did a poor job with the timing of the storm activity yesterday and last night. Given the same environment, confidence is moderate that the current timing will be accurate. If the same trend continues from yesterday, the storms will move in one to two hours later than what is forecast.

Tuesday will be similar to today. The ridge will remain unchanged and possibly intensify slightly more. Meanwhile another upper level short wave trough will move in from the west during the late afternoon/early evening. The model data differs regarding how strong this trough will be; if it will only extend over the southwest part of the forecast area or if it will extend over all of Eastern CO. Current model guidance is favoring the short wave trough only being over the far southwest part of the forecast area. However the data yesterday did kept the short wave trough shallow enough to not even move into the forecast area. Straight-line winds will continue to be the threat with any storms that form.

Highs for Tuesday afternoon will be a few degrees warmer than today. The heat index values are forecast to briefly reach 105F for locations east of Highway 83. Currently am not anticipating needing an advisory as the heat has been communicated other ways already.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 239 PM MDT Sun Aug 9 2026

***Tuesday***

A flattened ridge at 500-mb is favored to be in place overhead Tuesday morning. A shortwave trough embedded in the ridge favors a low developing at the surface across the forecast area. Surface winds are expected to be light as the low only undergoes weak to modest deepening and centers itself over the County Warning Area (CWA). Hot conditions look to continue under this setup, with highs currently forecast in the upper 90s to mid 100s. Confidence in a Heat Advisory being needed Tuesday continues to rise, currently around 40%. Additionally, dry conditions are forecast as light westerly to southwesterly surface flow continues to bring in dry air, and temperatures rise through the afternoon. Relative humidities are forecast as low as the upper teens across Eastern Colorado Tuesday afternoon. However, the risk for critical fire weather conditions is low due to the weaker surface winds. Confidence in a Red Flag Warning being needed is less than 5%. However, it should be noted that there is a small chance (20% chance or less) for showers during the evening hours Tuesday, particularly in West-Central Kansas and East-Central Colorado. NAMNST model soundings for 00z Tuesday show inverted-V profiles up to around 3 km, which may suggest the potential for dry lightning with these storms. This could serve as an additional form of fire starts.

***Wednesday/Thursday***

GEFS and EC ensemble guidance are in support of upper-level ridging remaining overhead through Thursday, as troughing builds in across the Western United States. The surface low from Tuesday looks to remain approximately stationary over the area Wednesday and Thursday. Easterly/northeasterly surface flow in Southern Nebraska ahead of southerly flow from the Gulf of America would support moisture returning to the area, in addition to temperatures beginning to cool. Highs are forecast in the 90s on Wednesday, and the upper 70s to upper 80s on Thursday. Additionally, LREF guidance shows a 75% chance or higher both Wednesday and Thursday for dewpoints greater than 60 F, most particularly across portions of Red Willow County in Southwest Nebraska, and Decatur and Graham Counties in Northwest Kansas. Thunderstorm activity appears more probable across the area as well. NBM 24 hr precipitation guidance shows probabilities in the 60-80% range across Southwest Nebraska and Northern Yuma County in Colorado for greater than 0.1 inches of rain Wednesday. These probabilities extend into Northwest Kansas and East-Central Colorado on Thursday. LREF guidance also shows that this activity will be in association with a 30-50% chance for surface CAPE (a measure of atmospheric instability) greater than 1000 J/kg. Thunderstorms are in the forecast both days, but the risk of them becoming severe is low at this time, as GFS and EC model soundings show less than 30 kts of sfc-500mb vertical shear both days. However, it is important to note that hotter conditions on Wednesday may promote microburst conditions with thunderstorms, which could be associated with 60-70 mph winds. Even so, confidence in severe weather occurring is about 5% each Wednesday and Thursday.

***Friday-Sunday***

Deterministic guidance diverges a bit by Friday, though ensembles continue to show troughing off to the west alongside ridging overhead. As such, conditions similar to that of Wednesday and Thursday are forecast, though there is some uncertainty regarding whether storms will be severe or not. Still, NBM 24 hr precipitation guidance shows the highest probabilities for greater than 0.1 inches of rain across Eastern Colorado (60-75% through Saturday). As for temperatures, highs in the 70s and 80s are forecast to continue through the weekend.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1139 AM MDT Mon Aug 10 2026

VFR conditions forecast for the TAFs. Fog may again form at KMCK. However, the moisture advection does not look as favorable as last night, and probabilities for visibility under a half mile are lower than last night. If fog should form it would be in the 10-14z window.

Main focus is storm timing. Setup for the event looks very similar to yesterday. Main question is storm coverage and timing. At this time do not have enough confidence for storms to move over KGLD to include anything more than a VC mention. There maybe erratic winds with any storms as they approach KGLD. However there is low confidence in the timing of these storms. By the time storms reach KMCK they should be weakening, so a VCSH mention is appropriate.

GLD WATCHES/WARNINGS/ADVISORIES

KS...None. CO...None. NE...None.