Issue Date: 9/5/2016
Issue Time: 9:05 AM

NO FLOOD THREAT IS FORECAST.

Moisture has taken a significant dip since yesterday afternoon as dry southwest flow aloft has overspread Colorado. This drier air is very apparent in the IPW chart below, showing values steeply declining for the last 12 hours or so. This drier air will result in much of the state experiencing a mostly sunny (and dry) Labor Day holiday. The exception to this rule will be across far southern and southeastern Colorado, along and east of a developing dryline. Weak support aloft will help kick off isolated thunderstorms in this area, with the main threats being strong winds and hail. Moisture values are too low to warrant any flood threat considerations.

Another threat today is the developing high fire danger across high valleys in the Northern Mountains and Front Range regions, across the Palmer Ridge, and for the lower valleys of far western Colorado. Relative humidity values will drop to near (or just below) critical values, and combined with the gusty winds, will bring the fire threat back into the discussion. A mitigating factor, so to speak, is recent days’ rainfall keeping most fuels above critically dry designation. However, locations that have not received much rain lately will have the driest fuels, and extreme caution needs to be exercised. For more information, including the exact location of Red Flag Warnings, please visit the website of your local National Weather Service office.

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

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

Mostly sunny and dry for most, with high temperatures a few degrees warmer than yesterday’s high temperatures. A couple isolated thunderstorms will develop across the far Southeast Plains and Raton Ridge regions, with the main threats being strong winds, hail, and lightning. Brief periods of light-to-moderate rainfall will also attend these storms, with maximum rain rates of 0.4-0.8 inches/hour. Minor street/field ponding may occur underneath the strongest storms, but no flood threat is warranted.

Timing: 1 PM – 9 PM, with one or two storms lingering until around midnight

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

Plenty of sunshine and dry conditions will be the main weather story today across these regions, with high temperatures similar to yesterday. High fire danger conditions exist across portions of the Front Range, Northern Mountains, Grand Valley, San Juan Mountains, and Southwest Slope regions, so please exercise caution if you plan on doing anything outdoors today. An isolated thunderstorm or two cannot be ruled out over far southern portions of the San Juan Mountains, San Luis Valley, and Southeast Mountains, as a subtle dry line lays across the region. The main threats from any storm activity will be gusty winds and lightning, with periods of light-to-moderate rainfall. Maximum rain rates will be 0.15-0.3 inches/hour.

Timing: Noon – 9 PM, with one or two isolated showers/weak thunderstorms developing overnight/early tomorrow morning

Issue Date: Sunday, September 4th, 2016
Issue Time: 9:10AM MDT

— Flooding is NOT expected today

After a prolonged period of widespread active weather, today will see a transitioning to overall quieter conditions. The large-scale disturbance that has been in our discussions for nearly a week now is still positioned west of Colorado. However, the main difference is that with strong southwesterly flow aloft, moisture has decreased significantly over most of Colorado today. The precipitable water chart, below, shows a unanimous decline at the five sites shown here (Denver, Boulder, Pueblo, Grand Junction and Colorado Springs) into the 0.6 to 0.8 inch range. The one exception to this conclusion is in the far northeast part of the state. There, a small pocket of moister air and instability will remain this afternoon. This is expected to cause scattered thunderstorms, capable of large hail up to 1.5 inches and a tornado or two. However, with steering winds of 40mph+, these storms could produce short-term heavy rainfall, but will simply not have enough time to cause a flooding threat.

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.

Issue Date: Saturday, September 3rd, 2016
Issue Time: 10:00AM MDT

— MODERATE flood threat for parts of Northeast Plains that received heavy rainfall yesterday
— LOW flood threat for parts of the Northeast Plains

The broad, low-pressure trough will continue to support scattered shower and storm chances across Colorado, as seen in the water vapor image below. For the vast majority of areas, this will be nuisance variety rainfall because low-level moisture has dropped over the past 24-hours. The only region of concern today is once again across the eastern Plains. A disturbance located across western Colorado will rapidly move east-northeast today. As it clips the northeast corner of the state, plenty of instability from widespread sunshine will combine with southeasterly moist flow to produce thunderstorms in the area. A Low flood threat is in place for parts of the region for isolated flash flooding. However, Moderate flood threat is in place for parts of Weld County and parts of Kit Carson and Cheyenne counties due to the high antecedent rainfall and thus high runoff from any additional rain that falls. For everyone else, enjoy a generally pleasant start to the Labor Day weekend!

Today’s Flood Threat Map

Issue Date: Friday, September 2nd, 2016
Issue Time: 10:30AM MDT

— MODERATE flood threat for Northeast Plains, Palmer Ridge and Southeast Plains
— LOW flood threat for Raton Ridge

A weather pattern change started for Colorado on Thursday as a large-scale upper trough began to impact the western part of the state. As the water vapor image shows, below, a disturbance emanating from this trough is currently positioned along the UT/CO border and will rapidly move through the state today. This disturbance is a bit stronger than even yesterday afternoon’s weather models suggested. Plenty of cloud cover is in place this morning, along with light to moderate showers mainly across the northern and western parts of the state. Cloud-free skies are found in the south and southeast and temperatures will rapidly climb to the 80s to near 90F. Moisture is in abundance today with precipitable water (PW) values at or above 1 inch east of the Continental Divide and in the 0.7 to 0.9 inch range to the west. As the disturbance moves east, moisture return will boost PWs as high as 1.5 inches across eastern Colorado. With plenty of instability available, expect a round or two of strong-to-severe thunderstorms over the eastern Plains. Very heavy rainfall will possible, though the overall threat is mitigated by the fast storm motion. Nonetheless, a Moderate flood threat is warranted for parts of eastern Colorado. Scattered to widespread showers and a weaker storm will occur across the western slope but lower instability and unfavorable dynamics mean that a flood threat is not warranted here.

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.