Area Forecast Discussion

KEY MESSAGES

- Slight risk for severe thunderstorms on Monday, though confidence is on the low side at this time.

- Fog may develop once again tonight and Sunday morning, and potentially Sunday night and Monday morning.

- Temperatures may reach the 100-105 range Tuesday and Wednesday. Critical fire weather conditions may be in place as well.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 1230 PM MDT Sat Jun 6 2026

A cut off low in the southern Plains today is being picked up by an approaching shortwave trough in the northern Rockies. CAMs show convection developing along the Front Range this afternoon with upslope flow as well as across southern Kansas with the southern system. It does not appear that storms will make it into the local area from either of those sources as they gradually dissipate this evening with loss of surface heating. Moist southerly flow continues tonight with low clouds and fog developing in the overnight hours. Models point to the Kansas and Colorado border area for the best potential for fog, which could be dense once again. The low clouds and fog will gradually burn off through Sunday morning.

Shortwave ridging will build over eastern Colorado and western Kansas on Sunday, ahead of the strong system over the northern Rockies. CAMs show widely scattered convection developing along the Front Range in the afternoon once again, but also possibly along the lee trough which will be further east in the plains. Instability and shear will be very weak further west, but if a storm manages to develop on the lee trough it would be closer to the better instability and shear in place near the Kansas border. Confidence is low in that scenario given the overall lack of forcing, and only the 3-km NAM shows an isolated updraft developing further east at this time. The isolated storm chances in western areas should end by 03z with loss of heating. A surface low is forecast to move from northeast Colorado to near Goodland Sunday night. May see low clouds and fog develop once again overnight and Monday morning with moisture advecting in from the southeast into Kansas and Nebraska, but westerly winds in Colorado and immediate adjacent counties in Kansas/Nebraska my prevent it from forming in those areas.

The surface low is forecast to move south and be in the Oklahoma and Texas panhandle by Monday afternoon. The central plains will have easterly upslope flow on the north side of the low. Aloft will be increasing southwesterly flow between a ridge over Texas and a strengthening closed low over Saskatchewan. There does appear to be a weak embedded wave in the afternoon that will provide some synoptic scale lift. Instability will be strongest east of Highway 25 where 2000-3000 j/kg is forecast, weakening to less than 1000 j/kg at the Colorado and Kansas border and further weakening in Colorado. Deep layer shear will be 30-40 kts with the increasing flow aloft and directional shear. So, if convection can develop the environment is supportive of supercells, especially in the better instability to the east. RRFS and REFS suggest a dry line will develop near Highway 27 which initiates convection, but the 3-km NAM has the dry line much further east into Colorado with little to no convection in the area. NBM is more supportive of the NAM at this time with broad southeasterly flow all the way to the Front Range. So unless the dry line is in the area as depicted by the RRFS the only forcing for initiation will have to come from the weak wave aloft. Given all of the uncertainty, confidence is on the low side regarding severe potential.

LONG TERM /TUESDAY THROUGH FRIDAY/

Issued at 239 PM MDT Fri Jun 5 2026

***Synopsis***

Monday morning, ridging is favored overhead at 500-mb. This looks to transition into southwesterly flow as broad troughing develops across the Western United States throughout the day. GEFS and EC 500- mb mean-spread guidance favors this upper-level pattern to persist through the end of the forecast period. A shortwave system embedded in this southwesterly flow looks to impact the forecast region Tuesday through Thursday as well.

***Monday***

A surface low pressure traversing the forecast area Monday morning may support northerly surface winds early in the day, though GEFS and EC members suggest the formation of a weak, broad surface low across the west during the afternoon. This would allow surface winds to have a southerly component by the evening hours. Even so, high temperatures on Monday are still forecast in the upper 80s to mid 90s. Showers may develop across portions of the area Monday afternoon and evening as well. The favored zone for convection appears to be along a warm front associated with the initial surface low passing through the area. LREF guidance suggests that these showers may be associated with up to 3000 J/kg of surface based CAPE (a measure of atmospheric instability). However, the same guidance suggests 90th percentile 500-mb winds around 30 kts. While organized thunderstorms could develop, vertical wind shear may be lacking. If this is the case, convective mode would likely stick to thunderstorms that are strong around the time of initiation, but are brief in nature. Still, severe weather is possible if 90th percentile or higher winds at 500-mb can be experienced. GFS model soundings are suggestive of SHIP (significant hail parameter) values around 1.5, which could support 2-inch hail in the strongest thunderstorms. Confidence in a severe weather event on Monday rests around 5-10%.

***Tuesday - Wednesday Evening***

Southerly flow is forecast to remain in place through Wednesday afternoon ahead of the strong upper-level shortwave trough. Forecast guidance suggests high temperatures will be hot, with much of Northwest Kansas and Southwest Nebraska between 100 and 105 degrees Tuesday and Wednesday. While the southerly return flow is favored to contain moisture, hot temperatures could keep relative humidity (RH) values low. Forecast guidance suggests RH will drop into the low to mid teens Tuesday, and upper single- digits to mid teens Wednesday. Critical fire weather conditions may be in place both days. NBM guidance suggests greater than a 50% chance for wind gusts to exceed 30 mph Tuesday and Wednesday across much of the County Warning Area (CWA). This is in addition to LREF guidance suggesting a 30-50% chance for RH values to drop into criteria for critical fire weather across Eastern Colorado Tuesday. Dry conditions may stretch further east Wednesday, as portions of Southwest Nebraska and Northwest Kansas also have a 30-50% chance for RH meeting criteria for the hazard, and up to a 75% chance in portions of Eastern Colorado. Confidence in a Red Flag Warning being needed is highest on Wednesday, around 30%.

***Wednesday Night - Friday***

Passage of the upper-level shortwave trough looks to promote a cold front overnight Wednesday, allowing slightly cooler temperatures through the remainder of the week. High temperatures are forecast in the lower to upper 90s Thursday, and mid 80s to lower 90s Friday. Critical fire weather conditions may linger into Thursday, with forecast RH values in the low to mid teens. However, wind gusts do not look to be as high as Tuesday and Wednesday, with the current forecast in the 20-30 mph range. NBM guidance does still suggest around a 2/3 chance or greater for wind gusts to exceed criteria (25 mph or greater) for critical fire weather across Eastern Colorado, but less across Northwest Kansas and Southwest Nebraska. Confidence in a Red Flag Warning being needed Thursday afternoon is much lower than Tuesday and Wednesday, around 10%. Cooler conditions on Friday lower the risk for critical fire weather even further. Chances for precipitation may increase on Friday as well, as troughing continues to exist to the west. NBM 24-hr precipitation guidance suggests up to a 25% chance for greater than 0.1 inches of rain across portions of Northwest Kansas from Friday's activity.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1112 PM MDT Fri Jun 5 2026

VFR conditions are currently in place across the area but with increasing moisture through the night am monitoring for fog and stratus overnight. Confidence is highest at MCK for IFR to LIFR ceilings and some fog. GLD is a bit more conditional as the signal has consistently remained around 30-60 miles north of the terminal but an over performance of dew points currently has my attention. Will leave GLD VFR for now but will watch closely over the next few hours. Fog and stratus are forecast to dissipate mid morning but winds are forecast to increase late morning and through the early evening hours.

GLD WATCHES / WARNINGS / ADVISORIES

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