FTB 06-27-2016: Low Flood Threat Returns

Issue Date: 6/27/2016
Issue Time: 9:05 AM


Current water vapor analysis shows the building ridge across the southwestern US with general trough-ing over the central US. Northwesterly flow aloft is in place over Colorado, while a shortwave trough pivots across the north-central US. In the wake of this shortwave trough, a cool front will push through eastern Colorado later this morning/early this afternoon, reinforcing easterly upslope flow and low-level moisture along the Front Range and eastward across the plains.

Steep lapse rates above the increase in moisture will support strong instability this afternoon across the Northeast Plains. Combined with sufficient wind shear, discrete supercell thunderstorms will be the preferred storm type, at least during the first few hours of storm activity. These storms will be capable of very large hail (up to 2.5 inches in diameter), periods of heavy rain, and isolated tornadoes. As the evening wears on, interactions between storms will lead to clusters, transitioning the main threat to damaging winds and hail up to 1.5 inches in diameter.


Back across the Front Range/Urban Corridor/Palmer Ridge/Southeast Plains/Raton Ridge, moisture will be a bit less, leading to more moderate instability. Storms will be a bit less vigorous, with the main threats being hail (up to 1.5 inches in diameter), strong winds, and periods of moderate-to-heavy rainfall. Storm coverage will be more isolated-to-widely scattered in these regions, with the best relative coverage over the Palmer Ridge, and Southeast Plains as storms move into the region from the Northeast Plains.

West of the Continental Divide, a lack of moisture will keep the area mostly sunny and mainly dry, with a few isolated storms over the higher terrain. Any storm activity will be high-based, leading to more gusty winds and lightning than rain. For more details regarding timing and rain rates, please see the zone-specific discussions below.

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.

Flood Threat Legend

Zone-Specific Forecasts

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

Isolated-to-widely scattered thunderstorms are expected to break up the otherwise partly sunny skies today. A couple strong/severe storms are a good bet across the Northeast Plains where the environment will support very large hail, damaging winds, and isolated tornadoes. Periods of heavy rain will also accompany these storms. For the other regions, thunderstorms will be more isolated and a bit less vigorous, but will still hold the potential for strong winds, hail, and periods of moderate-to-heavy rainfall. Maximum rain rates are as follows:

Northeast Plains: 2.0-3.0 inches/hour
Front Range: 1.0-1.5 inches/hour
Urban Corridor, Palmer Ridge, and Southeast Plains: 1.2-1.8 inches/hour
Southeast Mountains and Raton Ridge: 0.6-1.0 inches/hour

Timing: Noon – 9 PM for mountain regions, 1 PM – Midnight for others (with a few storms continuing over the Southeast Plains into the morning hours)

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

Isolated, gusty thunderstorms possible over the higher terrain of the Northern Mountains, Central Mountains, San Juan Mountains, and Southwest Slope. All other locations will remain dry and hot. Skies will be mostly sunny across most locations, with partly sunny skies near the higher terrain seeing the isolated storm activity. Maximum rain rates will be 0.4-0.6 inches/hour.

Timing: Noon – 9 PM, with a couple lingering isolated storms over the San Juan Mountains into the early AM hours

STP 06-27-2016: Isolated-to-Widely Scattered Thunderstorms Rumbled

Issue Date: Monday, June 27th, 2016
Issue Time: 9:00 AM MDT


Moisture to the east fought back against drier air moving in from the west, providing enough fuel for the development of isolated-to-widely scattered showers/thunderstorms. Activity began during the afternoon hours, with most ending by 9-10 PM. There were a few isolated storms that continued across the Northeast Plains this morning.

The main threats were gusty winds and lightning as most activity remained fairly high-based. However, over the Northeast Plains, better moisture was present and storms were also accompanied by periods of moderate-to-heavy rainfall. Over western Colorado, yesterday was marked by hot and sunny conditions as the dry air was the dominant force.

No flash flooding was reported yesterday. For a statewide look at 24-hour precipitation totals, please take a look at the Storm Total Precipitation map below.

Storm Total Precip Legend

FTB 06-26-2016: Fewer Thunderstorms Today

Issue Date: 6/26/2016
Issue Time: 10:05 AM


The water vapor image below tells the main story of today’s forecast as westerly flow aloft has continued to transport drier air into Colorado. The drier air, along with no disturbances to be found, will lead to a significant downtick in showers/thunderstorms as compared to the past couple of days. However, sufficient instability and moisture will remain for the production of isolated-to-widely scattered showers/storms across the following regions: Northeast Plains, Urban Corridor, Palmer Ridge, Front Range, Central Mountains, Southeast Mountains, San Juan Mountains, Raton Ridge, and Southeast Plains.


Due to the overall reduction in deep moisture, especially in more flood susceptible areas, no flood threat is forecast. A couple of strong-to-severe storms will develop over the plains, but observed/forecast soundings suggest more of a damaging wind threat than heavy rain. Temperatures will rise a couple of degrees for most locations today, with the biggest jump expected across northeastern Colorado.

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.

Flood Threat Legend

Zone-Specific Forecasts

Northeast Plains, Urban Corridor, Palmer Ridge, Raton Ridge, and Southeast Plains:

Isolated-to-widely scattered showers/thunderstorms will break up the otherwise mostly sunny sky. Areas along/near the higher terrain of the Front Range/Southeast Mountains, as well as near the preferred terrain of the Cheyenne Ridge/Palmer Ridge/Raton Ridge will have the most coverage, relatively speaking, thanks to orographic influences. Microbursts are possible under the stronger storms, and gusty winds/lightning will be the main threats. Maximum rain rates are as follows:

Urban Corridor: 0.4-0.8 inches/hour
Palmer Ridge: 0.5-1.0 inches/hour
Northeast Plains: 1.0-2.0 inches/hour
Southeast Plains and Raton Ridge: 1.2-1.8 inches/hour

Timing: 1 PM – 9 PM

Outflow boundaries from afternoon convection across western KS/NE and southern WY will need to be monitored this evening. An isolated thunderstorm or two will be possible as they converge across the Northeast Plains/Palmer Ridge from 9 PM – 3 AM. If these storms develop, they will likely produce the heaviest rain of the day, with maximum rain rates of 1.5-2.0 inches/hour. These storms will not persist long, due to less instability after sunset and a neutral atmosphere above.

Front Range, Central Mountains, San Juan Mountains, San Luis Valley, and Southeast Mountains:

Isolated-to-widely scattered showers/thunderstorms are expected to develop this afternoon/evening. The main threats will be gusty winds/lightning as moisture is significantly lower than previous days. Maximum rain rates will be 0.3-0.6 inches/hour. The San Luis Valley will remain mainly dry, with areas near the surrounding higher terrain seeing the best chance for any storm activity.

Timing: Noon – 9 PM

Northern Mountains, Northwest Slope, Grand Valley, and Southwest Slope:

Mostly sunny and hot, with temperatures pushing a couple degrees warmer than yesterday. Isolated cumulus clouds will develop over the higher terrain of the Southwest Slope and Northern Mountains, with perhaps a few patches of virga underneath the high bases.

STP 06-26-2016: Bulk of Precipitation Occurred Over Southeast Colorado

Issue Date: Sunday, June 26th, 2016
Issue Time: 9:00 AM MDT


Dry air aloft worked in from the west/northwest yesterday while a cool front drifted southward across the state. These two features, if you will, set up the southeastern quadrant of Colorado to receive the bulk of rainfall yesterday. A few isolated showers/weak thunderstorms dotted areas of the northern Front Range/Urban Corridor, Northern Mountains, Central Mountains, San Juan Mountains, and Southwest Slope, but those resulted in more gusty winds and virga than rainfall.

Scattered-to-widespread showers and thunderstorms worked across the southern Front Range, Urban Corridor, Palmer Ridge, Southeast Plains, Southeast Mountains, and Raton Ridge. A few strong thunderstorms were able to develop, fueled by good instability. Storm reports from yesterday include:

0.75 inch hail: 3 miles ESE of Perry Park (Douglas County) and 3 miles N of Larkspur (Douglas County)
60 mph Thunderstorm Wind Gust: 4 miles S of Cheraw (Otero County)
Thunderstorm Wind Damage: 3 miles N of Ordway (Crowley County), 5 miles NE of Blende (Pueblo County)

No flash flooding was reported yesterday. Please see the STP map below for a look at 24-hour precipitation totals.

Storm Total Precip Legend