Issue Date: Wednesday, June 28th, 2017
Issue Time: 11AM MDT

— Flooding is NOT expected today
— Extreme fire danger for western Colorado

There will continue to be contrasting weather stories across our state today, where the weather never ceases to amaze. Regarding rainfall chances, a marginal amount of low-level moisture will hold on during the afternoon and evening hours along the KS/NE borders, which combined with favorable shear profiles could produce severe storms. Large hail, gusty winds and a tornado threat will be in the realm of possibilities today. Very short-duration heavy rainfall will be possible, but flooding is NOT expected.

Perhaps the bigger story, however, will be the extreme fire danger in the western part of the state where low relative humidity (see water vapor image below), gusty winds and hot temperatures will create a dangerous situation for spreading fires. Hikers/campers – please be cautious.

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, scroll below the map.

Zone-Specific Forecasts:

Northeast Plains, Southeast Plains:

Partly cloudy with isolated to scattered thunderstorms possible after noon. Max 30 minute rainfall up to 0.8 inch and max 1-hour rainfall up to 1.2 inches will be just under flood intensity; thus no threat is issued. However, severe weather will be possible, including hail up to 2.5 inches, gusty winds up to 70 mph and an isolated tornado.

Primetime: 2PM to 11PM

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

Sunny early then partly cloudy with an isolated shower or perhaps a weak thunderstorm possible during the afternoon before the boundary layer mixes out. Max 30-minute rainfall 0.3 inches. Flooding is not expected today.

Primetime: 1PM to 8PM

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

Mostly sunny and hot today. An isolated shower or weak thunderstorm cannot be ruled out over higher terrain near the WY border. Max 1-hour rainfall up to 0.2 inches. Gusty winds and dry lightning will be more of a threat than rainfall. An extreme fire danger exists today, with a Red Flag warning in effect for most of the area. Please stay tuned to local National Weather Service offices for updates.

 

Primetime: 11AM to 7PM

Issue Date: Tuesday, June 27th, 2017
Issue Time: 10:50AM MDT

— Flooding is NOT expected today

After several days of elevated moisture across eastern Colorado, this morning’s water vapor imagery, below, suggests drying will overtake most of the state. This is courtesy of an approach disturbance that is causing lifting motion and showers/storms across WY and MT. For Colorado, however, the dry air will be the stronger hand today. Although isolated to scattered storms will be possible, especially across the higher terrain as well as eastern Colorado, rain rates will be below flood-threat intensity. Thus, flooding is not expected today.

In the far northeast corner of Colorado, severe weather will be possible later this afternoon as an incoming jet streak creates a favorable shear profile for strong, rotating updrafts. Large hail, up to 2.5 inches and gusty winds will be the main threat. Storm motions will be 30mph or greater, limiting heavy rainfall in a given locale.

Today’s precipitation probability map is shown 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, scroll below the map.

Zone-Specific Forecasts:

Northeast Plains:

Sunny early then partly cloudy with isolated to scattered thunderstorms possible after noon. Max 30 minute rainfall up to 1 inch and max 1-hour rainfall up to 1.4 inches will be just under flood intensity; thus no threat is issued. However, severe weather will be possible, including hail up to 2.5 inches and gusty winds up to 65 mph.

Primetime: 2PM to 9PM

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

Sunny early then partly cloudy with isolated showers and perhaps a weak thunderstorm during the afternoon. Max 30-minute rainfall 0.5 inches. Flooding is not expected today.

Primetime: 12PM to 8PM

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

Mostly sunny and slightly cooler today. An isolated shower or weak thunderstorm will be possible especially over northern areas and higher elevations. Max 1-hour rainfall up to 0.4 inches. Gusty winds and dry lightning will be more of a threat than rainfall.

Primetime: 11AM to 7PM

Issue Date: Monday, June 26th, 2017
Issue Time: 10:10AM MDT

— LOW flood threat for parts of Palmer Ridge (including Waldo Canyon burn scar), Southeast Mountains, and Raton Ridge

Although aloft, the weather pattern of the last 48 hours has hardly changed, the details of the lower levels will be important today. The water vapor image, below, continues to show a seasonably strong high-pressure ridge over the Great Basin. This is causing very warm and dry weather west of the Continental Divide. East of the Continental Divide, a different headline is in store today: very moist low level air. For example, at Colorado Springs, the morning dew point temperature was at 59F – a very high reading especially above 6,000 feet. More of the same is true farther south and east, where yesterday’s rainfall is evaporating and will continue to do so as the strong June sun heats the surface. Isolated to scattered thunderstorms will once again be likely today across the higher elevations and foothills of southeast Colorado. While rainfall rates will be right in the neighborhood of flood-intensity levels, a complicating factor today is antecedent rainfall. Parts of southeast Colorado saw over 0.75 inches of rainfall yesterday, causing areas with saturated soil. Today’s precipitation probability map looks almost identical to yesterday’s observed rainfall map (see Storm Total Precipitation summary). Thus, a Low flood threat is posted for parts of southeast Colorado for isolated flash flooding, debris slides and mud flows.

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, scroll below the map.

Zone-Specific Forecasts:

Southeast Plains, Palmer Ridge, Southeast Mountains, Raton Ridge, San Luis Valley, San Juan Mountains:

Sunny early then partly cloudy with isolated to scattered showers and thunderstorms developing by noon. Max 30-minute rainfall up to 0.8 inches and 1-hour rainfall up to 1.3 inches except up to 2.1 inches far southeast. Antecedent wet soils will increase the runoff threat today, thus a Low flood threat has been posted for isolated flash flooding, mud flows and debris slides. The Waldo Canyon burn scar should be monitored closely.

Primetime: 1PM to 11PM

Northeast Plains, Urban Corridor, Front Range:

Sunny early then partly cloudy with isolated showers and thunderstorms possible after noon. The chance of thunderstorms is slim today but if one manages to form, max 30-minute rainfall up to 0.8 inches and 1-hour rainfall up to 1.3 inches is possible. No flood threat is issued today due to low storm probabilities, but if a storm forms, isolated flash flooding will be possible.

Primetime: 2PM to 9PM

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

Mostly sunny to partly cloudy and continued very warm today. An isolated shower or weak thunderstorm will be possible especially over southern areas. Max 1-hour rainfall up to 0.5 inches. Gusty winds and dry lightning will be more of a threat than rainfall.

Primetime: 12PM to 7PM

Issue Date: Sunday, June 25th, 2017
Issue Time: 9:20 AM MDT

A LOW FLOOD THREAT IS FORECAST FOR PORTIONS OF THE SOUTHEAST MOUNTAINS, FRONT RANGE, URBAN CORRIDOR, PALMER RIDGE, RATON RIDGE, AND SOUTHEAST PLAINS.

There isn’t *much* change from yesterday’s forecast in the general sense, as northwest flow aloft continues across the state, while low-level easterly flow holds moisture into eastern Colorado. Drilling down to the details, however, shows a slightly weaker cap in place around 700-600 mb. This will allow for a few more storms to fire (compared to yesterday), along and east of the Continental Divide. The greatest storm coverage will occur across the southern Front Range/Urban Corridor, Southeast Mountains, Raton Ridge, and Southeast Plains, where the best moisture resides and is in closest proximity to a mid-level shortwave expected to rotate across New Mexico. A low-end, low flood threat has been issued due to the chance for isolated strong-to-severe storms capable of producing brief periods of heavy rainfall. More isolated activity will occur across the northern Front Range, Urban Corridor, Palmer Ridge, Northeast Plains, and eastern portions of the Northern Mountains and Central Mountains.

Elsewhere across western Colorado, today’s forecast is nearly identical to yesterday’s forecast. Most areas will be basking in sunshine, with only a few cumulus clouds developing over the higher terrain as the afternoon heats up. The San Juan Mountains and San Luis Valley will have a few isolated showers/thunderstorms develop during the afternoon and evening hours, moving southeast with time into New Mexico. Moisture is fairly limited in these regions, so no flood threat is warranted.

Zone-Specific Forecasts:

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

Isolated-to-scattered showers/thunderstorms are expected today, with the greatest relative storm coverage over the southern Front Range/Urban Corridor, Southeast Mountains, Raton Ridge, and Southeast Plains. In general, storms will not produce rain rates capable of flash flooding, but a couple of isolated strong-to-severe storms will be capable of producing periods of heavy rain. Thus, a low flood threat has been issued. Maximum rain rates are as follows:

Front Range: 0.6-1.2 inches/hour
Urban Corridor, Palmer Ridge, and Northeast Plains: 1.0-1.5 inches/hour
Southeast Mountains: 1.0-1.25 inches/hour
Raton Ridge and Southeast Plains: 1.5-2.0 inches/hour

Timing: 1 PM – 11 PM, with a few lingering showers/storms into the morning hours

Northern Mountains, Central Mountains, San Juan Mountains, and San Luis Valley:

Isolated showers/storms are expected over eastern portions of the Northern Mountains and Central Mountains (Continental Divide), as well as over the San Juan Mountains and San Luis Valley. Western portions of the Northern Mountains and Central Mountains are expected to remain dry. Maximum rain rates are as follows:

Northern Mountains and Central Mountains: 0.3-0.5 inches/hour
San Juan Mountains: 0.3-0.6 inches/hour
San Luis Valley: 0.4-0.8 inches/hour

Timing: 1 PM – 10 PM

Southwest Slope, Northwest Slope, and Grand Valley:

Plenty of sunshine and warm temperatures will bring a pleasant end to the weekend. A few fair-weather cumulus clouds will develop over the higher terrain during the afternoon/evening hours, resulting in nothing more than shade from the sun.