textproduct: Goodland

KEY MESSAGES

- Severe storms are possible this evening with large hail likely around an inch and wind gusts up to 70 mph.

- A Flood Watch has been issued for Cheyenne (CO), Wallace, Logan, Gove, Greeley and Wichita counties through Sunday morning. The potential for another cluster or two of storms moving over areas that have seen 1-3 inches of rain each of the prior nights has resulted in a heightened risk of flooding and possibly flash flooding.

- Severe storms are possible again Sunday, albeit with a lower chance of occurring. The main risk area would be Eastern Colorado while the main threat would be wind gusts up to 60 mph. Flash flooding could be a concern depending on how much rain falls on Saturday.

- More seasonable temperatures through the weekend and into Monday.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 1215 PM MDT Sat Aug 15 2026

Saturday, high pressure sets up across the eastern southern Plains which sets up for a nice surge of monsoonal moisture for the area. Focus is on another shortwave within the mid level flow which will again be the source for shower and storms development starting across Colorado. Similar to previous days, a few areas of storms are forecast to develop. The first is the typical convection off of the Front Range that will again be driven by a shortwave within the flow. The second however looks to be along a cold front from the north during the evening hours. For zones one and two zones, do also have concerns for capping which may lead to storms waning in intensity or even fully dying out. A 3rd area is also seen across portions of the area as well. Confidence is a bit higher in the 1st and 3rd areas based on the past couple days. Currently am thinking that the 3rd area will be the dominant area of rainfall again as it is fueled by the jet. The difference for the day is that the jet is progged to be a little bit further to the east than the past few days. For the severe weather potential, each of these zones will have the potential for wind gusts of 60-70 mph, large hail may be possible as well but confidence has really decreased in that threat. Eastern Colorado may have the higher potential for hail and damaging winds but the last few days convection has really struggled once it enters our forecast area. I do have the same concern again today especially with the current cloud cover in place as temperatures have not be able to warm up very much. The 700mb jet seems to have had the biggest influence with severe winds the past few nights which the 12Z HREF MAX wind gust also suggests the same thing again as well for later this evening. With the continued cloud cover in place for the day, my confidence in severe weather occurring has decreased quite a bit as lapse rates should remain lower which is currently being realized in the 18Z SPC Mesoanalysis page.

With the recent heavy rainfall of 1-3 inches over the past couple nights for counties along and south of Highway 40 have concern that flooding may be become a bit more common overnight with the next cluster and having the higher confidence that it will develop have opted to issue a Flood Watch through Sunday morning. Cheyenne county Colorado was the difficult county to decide on as only their southern and southeast portions of the area saw the heaviest rain but with the potential that the same area could get impacted by the first and third cluster opted to include them in watch.

There is a scenario, where all three clusters survive into the area along with some overlapping of them which could lead to some flooding north of the Flood Watch or more serious flooding within the Flood Watch. Confidence in this scenario is only 5-10%, so not anywhere near high enough confidence currently to go broader with the Flood Watch. There is also a worst case scenario with less than 5% confidence that storms stall out with multiple outflow boundaries in the area which would have the potential to lead to a considerable flooding situation for somewhere in the forecast area. This is supportive by around 5 GEFS members and have also been seeing the potential the past few days, but the signal has not been consistent at all. All in all this forecast is currently a low confidence but could potentially have higher impacts.

Sunday, high pressure broadens out across the souther Plains which blocks our moisture into place. Cloud cover is forecast to remain thick through most if not all of the day helping keep temperatures in the upper 70s to mid 80s. Yet another shortwave is forecast to move off of the Rockies. Severe weather may be possible again but similar to today not impressive as we may not be able to warm up enough for storms to sustain themselves and may not even develop in the first place. Should storms develop they would favor eastern Colorado. If we are able to warm up enough then more isolated to widely scattered development could be possible across NW Kansas. Wind gusts up to 60 mph would be the mos likely hazard.

Monday, our region is forecast to be in a mostly zonal upper-level flow with some subtle ridging developing across the northern Rockies. Guidance suggests that showers and storms may again develop along a boundary on the northern end of an expanding high pressure over the southern Plains. There may be a low risk of severe weather with damaging winds currently appearing to the primary hazard. High temperatures for the day are forecast in the mid 80s across the area.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 1215 PM MDT Sat Aug 15 2026

Starting the extended period Tuesday, high pressure is forecast to continue to slightly extend northward across the area. The further north the high pressure can go then the warmer temperatures will be. Current forecast has temperatures returning to the mid to upper 90s, but if the high pressure can remain a little further south then highs in the upper 80s to low 90s would be common. The position of high will also dictate precipation chances as well. With the current forecast being on the warmer end this does decrease our precipitation chances as guidance indicates that a shortwave will develop on the northern periphery of the high. If storms were to develop, they would turn severe with damaging winds the main threat as they form a cluster and move to the southeast. Currently should storms develop the northern and eastern portions of the area would be favored.

Wednesday, has a similar pattern but is more dictate by the development of a ridge across the western CONUS. Again guidance indicates another shortwave within the flow which could move into the area and possibly entire most if not the entire forecast area. Current guidance indicates that shear is a little better around 35- 40 knots which could support a damaging wind and perhaps even large hail threat if storms don't grow upscale too quickly. Those two days will need to be continued to be monitored.

Thursday, through the end of the forecast period indicates that another strong ridge will develop across the western CONUS as warm temperatures in the low to mid 90s return. The amplitude of the ridge will dictate how warm it gets and if precipitation chances occur as we may continue to reside on the eastern side of said ridge.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1101 AM MDT Sat Aug 15 2026

VFR conditions are currently forecast for the majority of this TAF period. Watching a few sprinkles or light showers move up from the southwest towards KGLD but no impacts to the terminal is expected. Showers and storms are again forecast this evening for each terminal. Coverage of rainfall is still up in the air but could get started as early as 04Z. If storms clear out in time then similar to the past few days IFR to LIFR ceilings and minor reductions to visibility due to fog would occur.

HYDROLOGY

Issued at 1215 PM MDT Sat Aug 15 2026

With the recent heavy rainfall of 1-3 inches over the past couple nights for counties along and south of Highway 40 have concern that flooding may be become a bit more common overnight with the next cluster and having the higher confidence that it will develop have opted to issue a Flood Watch through Sunday morning. Cheyenne county Colorado was the difficult county to decide on as only their southern and southeast portions of the area saw the heaviest rain but with the potential that the same area could get impacted by the first and third cluster opted to include them in watch. I included Logan and Gove counties due to the further east 700mb jet which indicates to me that perhaps guidance isn't bringing the heaviest rain potential as far east as it should. The past few nights with a similar jet magnitude wise, albeit further west has been the most impressive in the heaviest rainfall and the continuous rainfall. Rainfall rates of at least 1.5 to 2.5 inches per hour again seems reasonable given the same setup as the previous days.

There is definitely lower confidence than what I would like to have at this time in the way that this event will pan out due to the multiple clusters of storms and the potential for outflows to completely disrupt environments. This is my theory as to why Hi-RES guidance has been struggling with overall evolutions and coverage which can be seen looking at various total QPF outputs which shows swaths of heavy rain going in varying directions at the 12Z Sunday time period. The one thing that all of them do agree with though is within the swaths of heaviest rain additional 2-4 inches with isolated up to 6 inches of rain is possible overnight across the watch area. Some guidance also indicates very slow Corfidi vectors around 10-15 knots which would indicate some training potential as well.

There is a scenario, where all three clusters survive into the area along with some overlapping of them which could lead to some flooding north of the Flood Watch or more serious flooding within the Flood Watch. Confidence in this scenario is only 5-10%, so not anywhere near high enough confidence currently to go broader with the Flood Watch. There is also a worst case scenario with less than 5% confidence that storms stall out with multiple outflow boundaries in the area which would have the potential to lead to a considerable flooding situation for somewhere in the forecast area. This is supportive by around 5 GEFS members and have also been seeing the potential the past few days, but the signal has not been consistent at all. All in all this forecast is currently a low confidence but could potentially have higher impacts.

GLD WATCHES/WARNINGS/ADVISORIES

KS...Flood Watch from 6 PM MDT /7 PM CDT/ this evening through late tonight for KSZ027>029-041-042. CO...Flood Watch from 6 PM MDT this evening through late tonight for COZ092. NE...None.