SPM 10-03-2018: Rosa Brings a Surge of Late Season Subtropical Moisture to Western Colorado

Issue Date: Wednesday, October 3rd, 2018
Issue Time: 09:55 AM MDT

Summary:

The main axis of subtropical moisture moved into western Colorado yesterday, which brought beneficial, widespread rainfall to the western slope. Rainfall began during the early morning hours over the San Juan and Central Mountains and moved north throughout the day. As storms moved to the north, they became more isolated in nature and higher totals were confined to the mountains. A second set of showers moved into the southwest corner during the evening hours, but limited instability kept storms more isolated and less convective in nature than forecast. Storm motion was fairly quick and with more stratiform rainfall, rather than convective rainfall, the ground was able to soak up most of the moisture.

The western slope is experiencing either extreme or exceptional drought conditions, so yesterday’s boost of moisture helped make some headway with the drought after a very dry September. Totals over western Colorado were generally in the 0.25 to 0.5 inch range with higher totals over steeper terrains. Radar rainfall estimates were just over 1.5 inches in northern Delta County with totals just over 1 inch in the San Juan Mountains. The largest CoCoRaHS observation for the day was over Gunnison County near Crested Butte, which was 1.32 inches. The Columbus Basin SNOTEL site near Lewis Mountain (north of Hesperus, CO) recorded 1.9 inches for the 24-hour period. Thankfully, 1-hour rain rates yesterday were less than 0.5 inches, so there was not much of a flood threat even for recent burn scars. Flooding was not reported on Tuesday.

To see how much rain fell over your neighborhood yesterday, scroll down to the State Precipitation Map below.

Click Here For Map Overview

The map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (QPE) across Colorado. The map is updated daily during the operational season (May 1 – Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where flash flooding may have occurred). The 24-hour, 48-hour and 72-hour total precipitation contain bias corrections that are not disaggregated into the hourly estimates, so there will likely be some differences. The accumulation ending time is 7AM of the date shown in the bottom right corner. Also shown optionally are fire burn areas (post 2012), which are updated throughout the season to include new burn areas. The home button in the top left corner resets the map to the original zoom.

SPM 09-30-2018: Warm and Dry During the Day, Cool Front Pushed Southward Overnight

Issue Date: Sunday, September 30th, 2018
Issue Time: 9:30 AM MDT

Summary:

NOTE: This is the last scheduled State Precipitation Map (SPM) discussion of the 2018 season. However, additional discussions may be necessary this next week to cover the heavy rainfall threat possible across Western Colorado. If a flood threat appears, we will be doing special Flood Threat Bulletin(s), and SPM discussions, as warranted.

The main weather stories during the day yesterday were (1) the wild swing upward in high temperatures across eastern Colorado, where highs were 20-35°F warmer than the day before, and (2) the elevated fire danger brought on by warm, dry, and breezy conditions, especially over the High Country. Overnight and this morning, a weak surface low and attendant cold front pushed southward through eastern Colorado and brought low clouds, fog, and a few pockets of light drizzle to the eastern plains. The drizzle did not result in anything more than a trace accumulation, and was the only precipitation that Mother Nature could muster over the last 24 hours.

No flash flooding was reported yesterday. For a look at precipitation estimates in your area, please see the State Precipitation Map below.

Click Here For Map Overview

The map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (QPE) across Colorado. The map is updated daily during the operational season (May 1 – Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where flash flooding may have occurred). The 24-hour, 48-hour and 72-hour total precipitation contain bias corrections that are not disaggregated into the hourly estimates, so there will likely be some differences. The accumulation ending time is 7AM of the date shown in the bottom right corner. Also shown optionally are fire burn areas (post 2012), which are updated throughout the season to include new burn areas. The home button in the top left corner resets the map to the original zoom.

SPM 09-29-2018: Taste of Fall for Eastern Colorado

Issue Date: Saturday, September 29th, 2018
Issue Time: 9:30 AM MDT

Summary:

A shallow cold front pushed through eastern Colorado yesterday, providing a day filled with low clouds across much of the area. High temperatures struggled to get into the 50s, with much of the eastern plains remaining in the 40s throughout the day. There wasn’t enough moisture to get any showers going, except a light sprinkle or two across northeast Colorado. The cold air was only about 1000-1500 feet deep, so the High Country remained under the influence of sunshine and mostly sunny skies, with high temperatures similar to those of Thursday.

No flash flooding was reported yesterday. For a look at precipitation estimates in your area, please see the State Precipitation Map below.

Click Here For Map Overview

The map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (QPE) across Colorado. The map is updated daily during the operational season (May 1 – Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where flash flooding may have occurred). The 24-hour, 48-hour and 72-hour total precipitation contain bias corrections that are not disaggregated into the hourly estimates, so there will likely be some differences. The accumulation ending time is 7AM of the date shown in the bottom right corner. Also shown optionally are fire burn areas (post 2012), which are updated throughout the season to include new burn areas. The home button in the top left corner resets the map to the original zoom.

SPM 09-28-2018: Dry Weather Continues with Northwesterly Flow Aloft

Issue Date: Friday, September 28th, 2018
Issue Time: 09:35 AM MDT

Summary:

A few degrees warmer than average temperatures across the state on Thursday, but much closer to seasonable highs. There was a line of clouds that extended from the northwest corner of the state to Kit Carson/Cheyenne County. Other than that, crystal clear skies. The upper-level ridge was centered to our west, so northwest flow aloft continued to pull in a dry air mass. This meant no measurable precipitation across the state yesterday. Clouds increased over eastern Colorado overnight and early this morning as a shallow cold front moved through the state. Overall, quiet weather day. Just a friendly reminder that tomorrow, Colorado is looking at an increase in critical fire weather, so please tune back into the FTB for more details. There was a link added to yesterday’s nice SPM discussion about the ongoing wildfires over the state. Hopefully tomorrow’s critical fire weather won’t affect the containment of the fires, especially the gains that were made on the Ryan and Silver Creek fires.

Taking a look back at September precipitation, southeastern Colorado saw near or above average rainfall for the month. Normally, there is a peak in western Colorado rainfall (associated with the monsoon) during September. However, western Colorado continued to see dry conditions, which was highlighted in the increase in area of extreme drought conditions. October is normally a slow rainfall month across the state, but hopefully some beneficial rainfall will occur early next week as moisture from Rosa is advected over western Colorado. The Colorado Flood Threat Bulletin ends on September 30 (Sunday); however, if a flood threat appears, we will be doing special Flood Threat Bulletin(s) as warranted.

To see how much rain fell over your area the last 72-hours, scroll down to the State Precipitation Map below.

Click Here For Map Overview

The map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (QPE) across Colorado. The map is updated daily during the operational season (May 1 – Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where flash flooding may have occurred). The 24-hour, 48-hour and 72-hour total precipitation contain bias corrections that are not disaggregated into the hourly estimates, so there will likely be some differences. The accumulation ending time is 7AM of the date shown in the bottom right corner. Also shown optionally are fire burn areas (post 2012), which are updated throughout the season to include new burn areas. The home button in the top left corner resets the map to the original zoom.