textproduct: Goodland

KEY MESSAGES

- Heavy rainfall may continue through the night leading to nuisance flooding concerns. - Storm chances continue through the weekend. Some may be severe and perhaps an increasing flooding concern.

- More seasonable temperatures through the weekend.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 1237 PM MDT Thu Aug 13 2026

A surface low is situated across the south east portion of the CWA this morning as a cold front moves follows in its wake this will help keep temperatures across northwestern portions of the area in the low to upper 80s for the day whereas ahead of the front mid to upper 90s is most likely. On the deformation zone of the low, mainly showers and weak storms are already developing this morning across eastern Colorado. This activity is forecast to push off to the northeast through the morning and early afternoon but don't believe it will have any impact on the afternoon and evening rainfall potential.

Our main show for showers and storms isn't forecast to begin until 23Z at the earliest. There looks to be two zones that will be the focus for storms this afternoon. The first will be from the west and tied to a shortwave from the higher elevations and is forecast to move WSW to NNE. Wind gusts up to 65 mph and hail around quarter size looks to be the primary impacts with this. The second is tied to our cold front this morning stalling out as a stationary front. A 700mb jet is forecast to develop as well and will aid in storm development. Guidance suggests that some cold pooling may evolve with these cells and if so wind gusts of 60-70 and perhaps as high as 75 mph would be on the table as this will be in the area of the highest microburst composite. Blowing dust still remains a concern as well especially with any cold pools. Visibility issues under one mile will be possible with the cold pools as our mixing heights are forecast to remain around 4000' AGL along with 0-2km lapse rates being around 8.5-9.0 C/KM and 2-2.5km lapse rates around 6.0c/km through around 03Z. If a cell can remain isolated for long enough some large hail threat could develop as well with hail up to ping pong balls possible as wind shear is forecast to be around 30 knots. NAMNEST still has a solution where the southern zone struggle to form. This currently seems to be an outlier based on what is being seen in 12Z HREF and REFS paintball but is something that still has to be taken into account and is the reason for not going higher on rainfall percentages as well.

Confidence is increasing in both of these areas of convection merging (should the southern one form) across Sherman/Thomas counties this evening. This is forecast to lead to some flooding concerns as well with PWATS of 1.5-1.8 across the area which anomalously high for the area at this point of August. Corfidi vectors are forecast to be around 10-20 knots which with the PWATS in place some areas could see 1 to locally 2 inch per hour rainfall rates. I did consider a Flood Watch for portions of the area but a few things are keeping my confidence down to around 30% in flooding however. The first is kinda obvious but we have been very dry for several weeks now so we should be able to soak up the water. The second is that the CAPE looks to generally remain below 500 j/kg during the time where any flooding will be a concern which brings my confidence significantly down that the rainfall rates would be there for . Everything else is there for flooding concerns however with slow storm motions, long skinny CAPE profiles and ample mid and low level RH.

Rainfall is forecast to continue through the night but losing intensity as CAPE continues to wane. Due to overall consensus with mid level moisture remaining and with the 700mb jet still in the area will continue rain chances through at least mid morning Friday. A very similar pattern to this evening is forecast to remain in place across the area. High temperatures are again forecast to be in the 80s to low 90s but if clouds can remain in the area longer then a few degrees may be able to get knocked off. With the mid level moisture remaining in place would not be overly shocked if spotty showers could remain through the day but confidence is not high enough to keep rain chances going. Similar to today another shortwave is forecast to move from the southwest across the area. Guidance has shifted this wave a little further east than what I was seeing yesterday so confidence in rainfall has increased. Our low level jet however isn't as focused on the area so while widespread rainfall is still on the table it may be a bit more broken up than what is expected to occur Thursday night. Severe weather does still look to be a concern with wind gusts up to 65 mph the most likely hazard. Some guidance does try to convect some discrete cells with slightly less wind shear in place than today but higher CAPE values which could lead to a conditional threat for large hail. Heavy rainfall is again forecast to be a concern but storm motions are forecast to be quicker than tonight, but CAPE values are forecast to be higher which could lead to better rainfall rates. Depending on how tonight pans out another flooding risk could be in place for those that see the most rainfall tonight. The event Friday night and perhaps the severe potential could be a bit longer than tonight perhaps going past midnight mountain time.

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 today a stationary boundary is forecast to set up which is forecast to also serve as another forcing mechanism for showers and storms. Watching the potential for bit better coverage as well during the evening hours of storms. The 12Z NAM shows a very wet scenario for the area with PWATS around 2 inches and slow storm motions. Some severe threat may be possible with winds up to 60 mph and perhaps hail up to half dollar size but think flooding may be more of the concern especially if enough rainfall pans out tonight and Friday night.

LONG TERM /SUNDAY THROUGH THURSDAY/

Issued at 302 PM MDT Thu Aug 13 2026

Sunday morning, ridging is favored at 500-mb just to the west of the forecast area, with its axis running from the Pacific Northwest through the South-Central Plains. This feature would be supporting a surface high pressure across the Northern Plains. At the same time, a broad surface low is forecast to be positioned across the Four- Corners Region and portions of West Texas. The surface high to the north and surface low across the Desert Southwest would support southerly winds meeting northeasterly to easterly winds in Kansas Sunday. Thunderstorms are possible under this weather pattern. NBM 24 hr precipitation guidance suggests a 25% chance or better for greater than 0.1 inches of rain across most of the forecast area, with the best chances across East-Central Colorado and West-Central Kansas (60-80%). Thunderstorms are not yet expected to be severe, as LREF guidance shows less than a 30% chance across the entire area that sfc-500mb wind shear will exceed 30 kts. However, GFS and EC model soundings show wind shear at or nearing 30 kts. If this is the case, some thunderstorms may be allowed to become marginally severe. Confidence in severe weather occurring Sunday is around 5%, though would increase if wind shear can continue to improve. Regarding temperatures, highs are forecast a bit cooler in the upper 70s to mid 80s, as northeasterly to easterly winds would tend to dominate over the southerly winds from the south.

A strengthening upper level low in Central Canada looks to enhance a 500-mb jet streak across the Northern Plains Monday. This would allow the surface high pressure to migrate into the Midwest, and support southerly winds across the forecast area, helping the broad low to the south. Forecast highs are still in the low to mid 80s, as the southerly winds look to be relatively weak, and some cloud cover may still be in place from Sunday's thunderstorms. Showers remain possible Monday, but are less likely than Sunday as convergence reduces across the region. NBM 24 hr precipitation guidance is in support of this solution, with most areas at less than a 30% chance to receive greater than 0.1 inches of rain (the exception being West- Central Kansas in the 30-40% range). Confidence in severe weather occurring is less than 5%, as LREF guidance continues to show less than a 20% chance for greater than 30 kts of wind shear across nearly the entire forecast area.

Deterministic GFS and EC model guidance begins to diverge by Tuesday, specifically regarding a trough off the United States West Coast moving inland. Looking at GEFS, EC, and LREF ensembles, the ridge from the Pacific Northwest to the South-Central Plains is forecast to remain in place, but flatten out a bit, as the trough off the West Coast remains off shore through the end of the period. However, these ensembles show high amounts of spread in 500-mb heights under and to the east of the trough to the west, which would suggest the trough is still capable of moving inland between Tuesday and the end of the forecast period. About 50-60% of LREF members are in support of the ridge remaining in place and the trough remaining off the west coast. If ridging is allowed to remain in place and just to the west of the forecast area, similar conditions to Sunday and Monday may remain, with cooler temperatures favored. However, if the trough is allowed to move inland, temperatures may reach back into the 90s, and possibly even the lower 100s along the US-283 Corridor. Additionally, relative humidities would have an opportunity to drop into the 20s based on LREF 25th percentiles.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1115 PM MDT Thu Aug 13 2026

For KGLD & KMCK... Rain and mist are forecast to start the period, with visibility generally between 4 and 9 statue miles. The rain should end roughly by 09Z for both sites, but low ceilings around 800-1000ft may move in shortly after that. If the low ceilings move in, they would likely persist though 13-15Z. Once any low ceilings break, VFR conditions should persist through the remainder of the period with winds generally below 10 kts. There is another chance for showers and storms after 03Z Saturday. KGLD would likely see any precipitation first, followed by KMCK closer to 06Z.

GLD WATCHES/WARNINGS/ADVISORIES

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