Issue Date: Friday, September 30th, 2022
Issue Time: 10:40AM MDT

— Flooding is NOT expected today
— Fire-Burn Forecast Summary: 3 burn areas under MODERATE threat, 6 burn areas under LOW threat; click HERE for more info

This is the last scheduled Flood Threat Bulletin for the 2022 season. It has been a pleasure to serve the state of Colorado for another flood season! The next FTB season begins on May 1, 2023.

The strong Low pressure center, shown below, will increase moisture and dynamics over the state today as it slowly moves southeastward and cuts itself off from the main steering flow. Already, it is helping to produce some showers and weak thunderstorms over portions of central and northern western Colorado. An increase in southwesterly flow is forecast across the state as the upper-level jet, associated with the Low, moves over the northwest corner of the state. While additional moisture advection is unlikely, it should help provide some additional lift and shear for storm development. One benefit of the jet being overhead will be fast steering flows, which should limit the flood threat from individual storms.

PW at Grand Junction has not changed much from yesterday and was measured at 0.78 inches. The majority of this moisture still looks to be above the boundary layer, thus any thunderstorms that do develop should only produce brief heavy rainfall and perhaps isolated outflow winds. PW at Platteville, over eastern Colorado, was measured at 0.62, so again, little change from yesterday. So, it looks like the main difference between yesterday and today will be that increase in mid and upper-level dynamics as well as a frontal boundary moving in from Wyoming and Utah. So, as daytime heating continues and upslope flow/dynamics increase, expect storms to become more scattered to numerous over western Colorado and the northern/central mountains. There is a high chance for training storms to develop over steeper terrain, which may help to increase local totals. However, embedded convection should be limited with only minimal instability forecast, so longer duration, gradual stratiform rainfall is expected to be the dominate storm type . With both 30-minute and 3-hour totals remaining under flood threat criteria, flooding is NOT expected today. Scroll down to the zone-specific forecasts for more details.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts:

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

Morning showers and thunderstorms should expand in coverage throughout the day with a second wave of storms arriving late this afternoon into the evening hours. Isolated max 30-minute rain rates up to 0.8 inches and 3-hour rain rates up to 1.5 inches will be possible. Some high elevation snow is likely to start developing around dusk with light precipitation lingering over the high terrain through tomorrow morning. Flooding is NOT expected.

Primetime: Ongoing to 11PM

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

Light rainfall is currently occurring over the northern Front Range. Storm coverage should be limited to the Front Range and adjacent eastern plains today. Isolated max 30-minute rain rates up to 0.5 inches and 3-hour totals up to 1.1 inches may be possible under the stronger storm cores that develop, but outside of nuisance ponding, flooding is NOT expected. As thunderstorms roll off the foothills later this afternoon, some strong, but brief outflow winds may also occur. Storms intensity should drop off by later this evening with some light rainfall possible over the northern Urban Corridor and Northeast Plains into tonight.

Primetime: 2:30PM to 10:30PM

Issue Date: Thursday, September 29th, 2022
Issue Time: 9:30AM MDT

— Flooding is NOT expected today
— Fire-Burn Forecast Summary: 1 burn area under LOW threat; click HERE for more info

Today will be a transition day between the warm, relatively dry weather that Colorado has seen over the past few days, to a cooler, rainier weather pattern setting up beginning tomorrow. As shown in the visible satellite image, below, the upper-level ridge continues to weaken to our southeast. This has allowed for the import of moister air of monsoonal/Pacific origin into our state this morning. Grand Junction’s PW has risen notably from 0.63 to 0.76 inches. Further east, Platteville has also seen some modest moistening with a PW rising from 0.48 to 0.63 inches over the past 24 hours. PW will continue to very gradually rise through the day, and over the next 24-48 hours. However, the majority of this will be above the boundary layer, and thus not very impactful for thunderstorm potential. As also seen in the visible satellite image, a strong trough has entered the Pacific Northwest as of this morning. It will move ESE into the Northern Rockies over the next few days, but help push a couple of weak disturbances (“X” in image below) across mainly northern Colorado today. With the enhanced dynamics, we expect an increase in shower and storm activity for mainly western Colorado. Scattered showers and storms are expected by early afternoon, and persisting into the evening hours. Although brief moderate rainfall intensity is possible, flooding is NOT expected today. A couple of showers and weaker storms could also persist into the early overnight hours over the Northern Mountains.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts:

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

Becoming mostly cloudy with scattered showers and storms developing by early afternoon. Max 30-min rain rates up to 0.5 inches are possible over far northern Colorado, and up to 0.4 inches elsewhere. Flooding is NOT expected today.

Primetime: Noon through 9PM, with isolated showers persisting into the early overnight hours

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

Mostly sunny and warm with high temperatures a few degrees above normal. Isolated showers and perhaps a weaker storm cannot be ruled out this afternoon and evening, especially closer to the foothills. Max 30-min rain rates up to 0.2 inches.

Primetime: 2PM through 7PM

Issue Date: Wednesday, September 28^th, 2022
Issue Time: 8:20AM MDT

— Flooding is NOT expected today

A strong incoming trough can just be seen entering the Pacific Northwest coast this morning (see water vapor image, below). However, it will be another 24-48 hours until we begin to feel the impact. For today, the upper-level ridge to our southeast has weakened a bit allowing for a modest push of monsoonal moisture, along with a couple of disturbances to make it into the Four Corners region. PW at Grand Junction has risen to 0.63 inches, though with a dry boundary layer. PW at the Platteville research site is also up slightly to 0.48 inches. Thus, we expect slightly higher storm coverage this afternoon as enough sunshine will develop 200-300 J/kg of CAPE instability. The highest coverage of storms will be over the central, southern and southwest higher terrain. However, a couple of showers may also make it onto the adjacent plains along the I-25 corridor mainly south of Colorado Springs. Only brief rainfall is expected today, along with brief gusty winds. Thus, flooding is NOT expected.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts:

Northern Mountains, Central Mountains, Grand Valley, Northwest Slope, San Juan Mountains, Southwest Slope, San Luis Valley, Southeast Mountains, Raton Ridge & Southeast Plains:

Variable cloudiness early then partly cloudy with widely scattered to scattered showers and a few weaker storms this afternoon. Max 30-min rain rates up to 0.4 inches. Flooding is NOT expected today.

Primetime: 1PM to 7PM

Northeast Plains, Front Range, Urban Corridor & Palmer Ridge:

Mostly sunny early, then becoming partly cloudy and warm with high temperatures a few degrees above normal. An isolated shower or weak storm cannot be ruled out, especially along and west of I-25. However, with max 30-min rain rates up to 0.2 inches, flooding is NOT expected today.

Primetime: 1PM to 7PM

Issue Date: Tuesday, September 27th, 2022
Issue Time: 9:25AM MDT

— Flooding is NOT expected today

There is some cloud cover and isolated light showers over northwestern Colorado this morning, which can be seen in the visible satellite image below. The cause of these are weak mid-level lift and a bit of moisture that has circulated under the ridge (orange “X”). The High will continue to sit south of the border today, which will help to rotate this weak shortwave and moisture eastward across the state. This and the diurnal flow are expected to return isolated to widely scattered PM storms to the high terrain. With PW estimated around a half inch and surface moisture still lacking, only brief light to moderate rainfall rates are expected under the small storm cores that develop. Some storms may move off the high terrain into the adjacent eastern plains with clockwise motion around the High. With PW at Platteville being measured at 0.52 inches, dew points only in the 30s °F to low 40s °F, and little to no moisture advection forecast this afternoon, only minimal rainfall activity is forecast with plenty of virga and gusty outflow winds possible. Best chance for brief moderate rainfall rates will be over the elevated ridges where extra convergence is forecast. Despite the uptick in the chance for rainfall today, flooding is NOT expected.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts: 

Southeast Mountains, San Juan Mountains, Northern Mountains, Central Mountains, Front Range, Raton Ridge & Palmer Ridge:

Isolated to widely scattered weak t-storms may be possible over these zones this afternoon. In addition to light to moderate rainfall rates, storms may produce some strong outflow winds, especially as they move into the adjacent plains. Max 30-minute rain rates up to 0.25 inches (north) and 0.4 inches (south) may be possible. Flooding is NOT expected.

Primetime: 12:30PM to 10PM

Northwest Slope, Grand Valley, Southwest Slope, Urban Corridor, San Luis Valley, Southeast Plains & Northeast Plains:

Another gorgeous dry and warm weather day is on tap. Best chance for rainfall will be over the immediate adjacent eastern plains this evening, but rainfall totals should remain under 0.2 inches. As storms move off the high terrain, they may produce some strong outflow winds before dissipating. Flooding is NOT expected.

Primetime: 4:30PM to 10PM