STP 09-25-2015: Picture Perfect Fall Day

Issue Date: 9/25/2015
Issue Time: 8:55AM


Mostly clear skies, seasonable temperatures and higher elevation fall color made for a textbook fall day across Colorado. High temperatures were in the mid-80s in the lowest elevations to upper-50s over the higher terrain. Some residual low-level moisture, possibly from the previous two days of rains, generated a few short-lived showers over the Southeast Plains. About a tenth of an inch of rain was reported in Pueblo County with several other reports of a trace. Otherwise, everyone else was fortunate enough to receive a full day’s sunshine.

Looking around the state for fall foliage reports suggests peak color is now occurring at the highest elevations, between 9,000 and tree line. We can expect this to progress downward into the lower elevations over the next month or so.

Flooding was not reported yesterday. For estimated rainfall in your area, check out radar-estimated map below.


FTB 09-25-2015: Sunshine Continues To Rule The Land

Issue Date: 9/25/2015
Issue Time: 8:35AM

— No Flood Threat Today

Coloradoans awoke to a seasonably cool start this Friday morning. The far northeast corner of the state was under the grips of a low cloud deck. Meanwhile, but all other areas were under clear skies. Another nearly cloud free day will boost temperatures to near seasonable levels today. Precipitable water values, shown below, continue to be subdued after peaking during the thunderstorm activity on Wednesday. Thus, aside from some morning sprinkles in the Northeast Plains, neither precipitation nor flooding issues are expected today.


Today’s Flood Threat Map

For more information on today’s flood threat, see the map below (hover over threat areas for more details). For Zone-Specific forecasts, jump below the map.

Zone Specific Forecasts

Front Range, Urban Corridor, Northeast Plains, Southeast Plains, Palmer Ridge, Raton Ridge, Southeast Mountains:

Mostly sunny skies with seasonable temperatures. Highs in the 50s in the highest terrain to the low-80s across the lower elevations. A few morning sprinkles are possible in the Northeast Plains, but everyone else will stay dry. Flooding is not expected.

Southwest Slope, San Juans, San Luis Valley, Central Mountains, Northern Mountains, Grand Valley, Northwest Slope, Southwest Slope:

Sunny skies for nearly all areas today. High temperatures will be seasonable, with readings in the 50s over the highest terrain to the mid-80s in the low elevations of the Colorado River valley. Flooding is not expected today.

FTO 09-24-2015: One Rainfall Event In Sight, But No Flood Threat

Issue Date: 9/24/2015
Issue Time: 12:15PM

Note: Our final Flood Threat Outlook is next Monday, 9/28. Please check back then for a special winter snowpack forecast!


The last week or so has seen a rekindling of heavy rainfall activity that was a staple during the early part of summer. Thunderstorms have occurred on several days, but due to marginal atmospheric instability and fast storm motion, heavy rainfall has been more a miss than a hit. During this Flood Threat Outlook, we anticipate a continuation of the transition from summer to fall. Weather-wise, this implies that the character of rainfall transitions from thunderstorm-driven to frontal driven.

watervapor_20150924The water vapor image, above, shows the main features of the middle and upper-atmospheric circulation. A strong jet stream is found across southern Canada, extending far upstream into the North Pacific Ocean. A significant trough was located off the North American west coast. This trough will very slowly enter the continent and provide Colorado with a multi-day period of rainfall chances. Farther west, another trough/low-pressure system spins in the North Pacific. At this time, no impact is expected from this feature.

Thus, only one precipitation event is identified during this FTO. Details of this event follow.

Event #1 (Tuesday 9/29 – Friday 10/2):

No Apparent Flood Threat

A large-scale trough is expected to slowly approach the west coast of the U.S. By Tuesday (9/29) of next week, this feature is expected to impact Colorado. Atmospheric instability will once again be limited. Thus, it is not clear if there will be a potential for thunderstorm activity. Regardless, the passage of one or two cold fronts will maintain a chance of rainfall from Tuesday through Friday. As the cold front passages will be swift, rainfall will be on the light side. However, in total, between 0.5 and 0.75 inches of rain will be possible in the Central Mountains, Northern Mountains as well as the Front Range, Palmer Ridge and Northeast Plains. Thereafter, additional cold front passages will be likely during the week of Monday, 10/5. However, there are presently no indications that these events will lead to rainfall exceeding 0.5 inches.


STP 09-24-2015: A Second Day Of Storms Across The Southeast

Issue Date: 9/24/2015
Issue Time: 9:20 AM


Thunderstorms once again moved across the landscape of the Southeast Plains and Palmer Ridge on Wednesday afternoon and evening. Coverage and intensity was not quite as high as Tuesday, but heavy rainfall was nonetheless observed. The highest 24-hour totals came from Otero and Baca counties where 1.08 and 0.98 inches were observed, respectively. However, our radar estimated map, below, suggests amounts up to 1.6 inches may have fallen over rural parts of southern Prowers and northern Baca counties. Separately, heavy rainfall was also observed over Kiowa County, prompting an Areal Flood Advisory.

On the other side of the Divide, showers and weak thunderstorms were observed over the San Juans with up to 0.8 inches of rainfall falling. Additionally, hail of 1.25 inch diameter was reported in La Plata County during the peak of the activity in the late afternoon.

For everyone else, it was a typical fall day with a few scattered showers amidst mostly sunny to partly cloudy skies.

Flooding was not reported yesterday. For estimated rainfall in your area, check out radar-estimated map below.