Issue Date: 7/1/2018
Issue Time: 6:45 AM

NO FLOOD THREAT IS FORECAST TODAY.

In the wake of yesterday’s upper-level trough, a drier and more subsident air mass has taken over Colorado. This will lead to a pleasant day overall, marked by plenty of sunshine and temperatures generally 6-10 degrees warmer than Saturday’s highs. During the afternoon/evening hours, a few isolated showers/garden-variety thunderstorms will break up the pleasant day over/near the higher terrain of the southern Front Range, the Central Mountains, Southeast Mountains, and eastern San Juan Mountains. A couple showers/storms will spill over the southern Urban Corridor, Palmer Ridge, and western portions of the Southeast Plains, but that will be about all that Mother Nature can muster. Storm activity will diminish near sunset as the daytime heat wanes, and come to an end by Midnight everywhere.

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

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

Plenty of sunshine and warmer temperatures will be the main weather story today, with highs in the 80s across the area, with a few locations ranging near 90s in the Southeast Plains. A couple isolated, high-based showers/thunderstorms will spill over areas along/near the higher terrain, south of I-70. Gusty winds and brief periods of wetting rainfall will be the main result from any activity. Maximum rain rates will be 0.25-0.5 inches/hour.

Timing: 3 PM – Midnight

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

Plenty of sunshine and warm temperatures are on tap today, making for a pleasant end to the weekend. A few isolated showers/garden-variety thunderstorms will break up the blue skies during the afternoon/evening hours over the Central Mountains and Front Range, the Southeast Mountains, and eastern portions of the San Juan Mountains. Rain rates will generally be below 0.10 inches/hour, with maximum rain rates as follows:

Central Mountains and San Juan Mountains: 0.15-0.20 inches/hour.
Front Range and Southeast Mountains: 0.2-0.3 inches/hour

Timing: 2 PM – 9 PM

Issue Date: 6/30/2018
Issue Time: 7:55 AM

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

A large-scale, low pressure trough will traverse the region today, bringing noticeably cooler temperatures and forcing for scattered showers and thunderstorms, mainly along and east of the Continental Divide. Acting alongside the upper-level trough is a weak surface cool front, currently situated roughly west-to-east across central Colorado, and will continue its trek southward through the afternoon. Behind the front, the arrival of cooler, moist air from the east/northeast will be the fuel for a few strong-to-severe thunderstorms this afternoon/evening across eastern Colorado. The stronger storms will be capable of periods of heavy rainfall, large hail, and strong winds, and this storm potential is the culprit behind the low flood threat.

West of the Continental Divide, the cool front and upper-level trough will result in mainly cooler temperatures as the low-levels simply remain too dry for the production of rainfall. The exception to this will be north of I-70, near the best upper-level support, where lift from the trough will be strong enough to generate scattered clouds and isolated showers/garden-variety thunderstorms, resulting in mainly virga and gusty winds with little rainfall.

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

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

Isolated-to-scattered showers/thunderstorms are expected this afternoon and into tonight, producing periods of moderate-to-heavy rainfall, with the strongest storms capable of large hail (up to 1.75” in diameter) and strong wind gusts (up to 70 mph). An isolated tornado or two cannot be ruled out over the eastern plains (this is Colorado, after all). Maximum rain rates are as follows:

Urban Corridor and Palmer Ridge: 0.8-1.2 inches/hour
Northeast Plains and Southeast Plains: 1.2-1.8 inches/hour
Raton Ridge: 0.6-1.0 inches/hour

Timing: 1 PM – 7 PM for the Urban Corridor, 2 PM – 8 PM for the Palmer Ridge, 2 PM – 11 PM for the Northeast Plains and Southeast Plains, and 1 PM – 8 PM for the Raton Ridge. Outflow boundaries moving back into the foothills during the late evening hours may generate a couple additional storms from 8 PM to Midnight across the southern Urban Corridor, Palmer Ridge, and Southeast Plains.

Front Range and Southeast Mountains:

Isolated-to-scattered showers/thunderstorms are expected this afternoon/evening, with the bulk of the activity over the Front Range due to its close proximity to the upper-level support. Brief periods of moderate-to-heavy rainfall, small hail, and gusty winds are the threats from storms. Maximum rain rates will be 0.6-1.0 inches/hour for the Front Range and 0.35-0.65 inches/hour over the Southeast Mountains.

Timing: 1 PM – 7 PM, with an additional storm or two generated by outflow boundaries moving back into the southern Front Range during the 7 PM – 10 PM timeframe

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

Noticeably cooler temperatures will be the main weather story today as the cool front pushes through and the upper-level trough passes overhead. Scattered clouds and a few isolated high-based showers/garden-variety thunderstorms will dot the Northern Mountains, higher elevations of the Northwest Slope, and northern portions of the Central Mountains. Due to the relative lack of moisture below cloud bases, virga and gusty winds will be the main result from any activity, with very little rainfall.

Timing: Noon – 6 PM

Issue Date: Friday, June 29, 2018
Issue Time: 08:50AM MDT

— Flooding is NOT expected today

High clouds have made their way into Colorado this morning thanks to a small shortwave that moved through the mid-levels and provided some lift. Flow in the upper atmosphere will be more southwesterly today as the disturbance to our west begins to dig south. The axis of the upper trough is marked with the orange line in the water vapor imagery below. Expect some more shortwave action this afternoon as the disturbance over Utah makes its way into the state. This should help spark some more widespread, high-based thunderstorms this afternoon and evening, especially over the higher terrains. There is also a weak cold front that will affect the northern half of the state today. This should knock down the high temperatures a few degrees, but that’s about all it can muster before it stalls out over the Palmer Divide. Moisture behind the front may increase a little bit, but overall, the lower atmosphere will remain quite dry.

So, as far as moisture goes, there isn’t much over the state. This will limit how much rain the thunderstorms can produce this afternoon. Precipitable Water at Denver this morning was measured at 0.32 inches and was measured at 0.3 inches over Grand Junction.  The large spread between the temperature and dew points means the main threat from the storms this afternoon will be gusty winds and plentiful virga. The high-based thunderstorms, gusty winds and low relative humidity will produce extreme fire danger across the majority of the state today prompting a Red Flag Warning.

A lee trough will set up this afternoon over the eastern plains, but it will be far enough east that the higher dew points will stay out of Colorado. Still, this area has the best chance for some measurable rainfall. Expect the storms that move off the higher terrains to strengthen a bit as they reach better moisture over the northwest and southeast corners of the state. These storms should move to east of Colorado by 10PM this evening. Flooding is not forecast today.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. For Zone-Specific forecasts, scroll below the map.

Zone-Specific Forecasts:

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

The heat is back again today. Over the northern portion of the state, the high temperature should decrease a little with the passage of a weak cold front this afternoon. However, the Southeast Plains are expected to hit 100F+ again. High-based thunderstorms will bring gusty winds to the higher terrains this afternoon. A Red Flag warning has been issued for critical fire weather over the Southeast Mountains, and breezy, dry conditions will not be helpful for the fight against the Spring Fire in Costilla County. The best chance for measurable rain will be over the far eastern plains with max 1-hr rain rates up to 0.4 inches/hour. To the west, total rainfall will be under 0.1 inches with most areas receiving abundant virga. Flooding is not expected today.

Primetime: 1PM to 10 PM

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

Dry, breezy conditions will place all of these regions under a Red Flag Warning today. The trough to the west will continue to tighten and increase wind speeds through tonight especially over the Northwest Slope. High temperatures will be a couple degrees cooler today, and cloud cover will increase over the higher terrains this afternoon. The strongest cloud cover and best chance for virga (and stronger winds) will be over the San Juan Mountains and Northwest Slope. Rain is not expected today.

Issue Date: 6/28/2018
Issue Time: 7:10 AM

NO FLOOD THREAT IS FORECAST TODAY.

Strong high pressure ridging continues to reside overhead, leading to another day of hot temperatures statewide. In fact, temperatures will again nudge up a few degrees over yesterday’s readings, with record high temperatures being threatened (and likely exceeded) at a number of locations across eastern Colorado. With the dry air in place, temperatures will warm up quickly and remain hot into the evening hours, so be sure to stay hydrated and find the shade as much as possible if you must be outside today. Red Flag Warnings are in place across much of the state, as well, so be sure to check with your local NWS office for more information.

A weak mid-level disturbance (red line) embedded in the southwesterly flow aloft will pass over the state today, working alongside daytime heating to trigger a few high-based showers/thunderstorms along/east of the Continental Divide. Much like yesterday, with the high temperature-dewpoint spreads in the low-levels indicating very dry air, little (if any) rainfall will reach the surface. Instead, activity will result in mainly strong winds with plenty of virga.

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

The heat will be the main weather story today, as high temperature records will be threatened everywhere, with a few records likely being broken. A few high-based showers/thunderstorms are expected during the afternoon and into the nighttime hours, resulting in strong winds and plenty of virga, but very little rainfall. Maximum rain rates will be less than 0.05 inches/hour over the mountains & foothills and less than 0.15 inches/hour over the plains.

Timing: Noon – 10 PM over the Front Range and Southeast Mountains, 1 PM – Midnight elsewhere, with a couple high-based showers hanging on near the CO/KS border into the early morning hours.

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

Hot, dry, and breezy will be the name of the weather game across these regions today, with Red Flag Warnings in place across the entire area from Noon-8 PM. A couple high-based showers over the higher terrain of the Central Mountains, San Luis Valley, and eastern San Juan Mountains are expected during the afternoon/evening hours, resulting in little (if any) rainfall, gusty winds, and plenty of virga. Maximum rain rates will be less than 0.05 inches/hour.

Timing: Noon – 9 PM