Issue Date: 6/22/2015
Issue Time: 9:20 AM

A MODERATE FLOOD THREAT CONTINUES FOR THE LEVEE BREACH ALONG THE SOUTH PLATTE RIVER IN MORGAN AND WASHINGTON COUNTIES, AS WELL AS ALONG THE SOUTH PLATTE RIVER ACROSS PORTIONS OF PARK, DOUGLAS, AND JEFFERSON COUNTIES. A MODERATE FLOOD THREAT IS IN PLACE FOR PORTIONS OF THE ARKANSAS RIVER AS SNOWMELT AND RESERVOIR RELEASES WILL KEEP RIVER LEVELS HIGH.

You will notice that today’s forecast mirrors much of the last few days’, with abundant sunshine and dry conditions in the forecast. Moisture has continued the overall downward trend over the last few days, easily seen in the IPW chart below. As of 8 AM, all four of the normal reporting stations – Boulder (blue), Grand Junction (green), Pueblo (pink), Shriever AFB (red) – were below 0.4 inches IPW. A cool front is currently cutting through eastern Colorado, reinforcing some moisture and bringing gusty, northerly winds. The main result from the front today will be slightly cooler high temperatures for the Urban Corridor, Northeast Plains, Palmer Ridge, and Southeast Plains regions. Over the mountains, temperatures will be nearly the same as yesterday, with the lowest valleys flirting with, and a few surpassing, 100 F for afternoon highs.

With the slight increase in low-level moisture and a bit of convergence along the frontal boundary, an isolated thunderstorm or two will be possible across southern Palmer Ridge, the Southeast Mountains, and Raton Ridge. The Southeast Plains near these preferred terrain zones will also hold the slim chance for an isolated thunderstorm late this afternoon and into the evening hours. With all of that said, however, warm air aloft is nearly identical to yesterday, and surface temperatures will be slightly cooler, meaning the cap will likely be tougher to break than yesterday. The difference lies in the front, and whether or not it can provide enough forcing for an isolated thunderstorm or two. At any rate, the main result will be locally gusty winds and lightning, with locally moderate rainfall. Maximum rain rates will be 0.6-1.2 inches/hour.

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

Mostly sunny and hot, with highs ranging from the 80s to upper 90s. An isolated, late afternoon/evening thunderstorm or two will be possible along the Southeast Mountains, Palmer Ridge, Raton Ridge, and adjacent portions of the Southeast Plains. Maximum rain rates will be 0.6-1.2 inches/hour, with the main threats being lightning and locally gusty winds.

Timing: 2 PM – 10 PM

After the low level jet kicks in late this evening, an isolated shower/weak thunderstorm will be possible (8 PM – Midnight) across the Northeast Plains. Heavy rain is not expected, as rain rates will be less than 0.5 inches/hour.

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

Mostly sunny and hot, with temperatures much like yesterday. Highs in the lowest valleys will inch a bit higher than yesterday, pushing temperatures to near, or just above 100 F. Fire weather conditions continue across portions of the Northwest Slope, so be sure and check with NWS Grand Junction for more details if you plan on being in that region today.

Issue Date: 6/21/2015
Issue Time: 8:53 AM

A MODERATE FLOOD THREAT CONTINUES FOR PORTIONS OF THE SOUTH PLATTE RIVER. A LOW FLOOD THREAT CONTINUES FOR PORTIONS OF THE ARKANSAS RIVER, SOUTH PLATTE RIVER, AND CACHE LA POUDRE RIVER. ADDITIONALLY, VARIOUS STREAMS/RIVERS CONTINUE TO RUN HIGH ACROSS WESTERN COLORADO.

It appears that Mother Nature received the memo that today is the first official day of summer. True to form, the hottest temperatures of the year so far will be felt across many locations today as high pressure ridging continues to build across the southwestern US. Expect today to be much like yesterday, with the exception that the atmosphere has dried out a bit more (see “Precipitable Water Table” below). With warm air aloft, the decrease in moisture will mean that the already small chances of firing any thunderstorm activity have become even slimmer, and any storms that do form will not pose a heavy rain threat. For more specifics on areas that could see an isolated storm or two, please jump down to the Zone-Specific Forecasts below the threat map.

One note of importance in today’s forecast is the fire weather conditions that have returned to the northwestern corner of the state. Red Flag Warnings have been hoisted for portions of Moffat and Rio Blanco Counties due to gusty winds, low relative humidities, and dry fuels. If you plan on being in those areas today, stay up-to-date with changing conditions by checking in with NWS Grand Junction.

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

Mostly sunny skies and hot temperatures will be the main story again today, with temperatures nudging up from yesterday’s highs. High temperatures will be in the low-to-mid 90s for many locations, reaching into the low 100s for some locations in the Southeastern Plains. An isolated storm or two will be possible in the Palmer Ridge, Raton Ridge, Northeastern Plains, and Southeastern Plains regions, though the likelihood is very slim. With temperatures climbing as high as they are forecast, plenty of instability will be available if, and only if, the cap of warm air aloft can be broken through. No heavy rain is expected, as the atmosphere is much too dry, but locally gusty winds and lightning will be the main threats. Maximum rain rates will be 0.2-0.4 inches/hour.

Timing: 1 PM – 8 PM

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

Mostly sunny and hot, with only a slim chance of an isolated weak shower/thunderstorm or two over the San Juan Mountains and Southeast Mountains. Any activity will be high-based, so no more than a sprinkle is expected. Red Flag Warnings have been issued for portions of the Northwest Slope, so be sure to check with NWS Grand Junction for more details.

Timing: 1 PM – 7 PM

Issue Date: 6/20/2015
Issue Time: 8:45 AM

A MODERATE FLOOD THREAT CONTINUES FOR PORTIONS OF THE SOUTH PLATTE RIVER. A LOW FLOOD THREAT CONTINUES FOR PORTIONS OF THE ARKANSAS RIVER, SOUTH PLATTE RIVER, AND CACHE LA POUDRE RIVER. ADDITIONALLY, VARIOUS STREAMS/RIVERS CONTINUE TO RUN HIGH ACROSS WESTERN COLORADO.

A phrase made famous by Buster Poindexter in 1987 describes the forecast well for today: “Hot Hot Hot.” The mercury will continue to climb into the upper 80s and mid 90s for many low elevation locations, and near 100 in the lower Arkansas River Valley and the lowest elevations of far western Colorado. If you plan on being outdoors today, be sure to pack the sunscreen, drink plenty of water, and take breaks out of the direct sunlight.

Similar to yesterday, a few isolated, high-based showers and weak thunderstorms will develop over the mountains, producing mainly gusty winds and lightning. Heavy rainfall will not be a threat from any storms over the higher elevations today. Locations to watch today for a stronger thunderstorm or two will be the Urban Corridor, Palmer Ridge, Northeast Plains, and Southeast Plains. IF a storm can develop in those regions (warm air aloft is still providing a stout cap that will be tough to break), it will have access to enough shear to bring locally severe wind gusts and small hail, but again, heavy rain will not be a threat today. The atmosphere is simply too dry, with precipitable water values below average statewide (see “Precipitable Water Table” above).

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

Mostly sunny and hot, with highs ranging from the upper 80s to the upper 90s. A few locations across the lower Arkansas River Valley will flirt with 100. A couple isolated, high-based showers/thunderstorms will be possible, mainly over and near favored terrain, but heavy rain will not be a threat. Only IF storms can develop, will they have the potential to produce locally severe wind gusts and small hail. Maximum rain rates will be 0.2-0.4 inches/hour.

Timing: 3 PM – 9 PM

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

Mercury will continue to climb high today, pushing temperatures near 100 for the lowest elevations of far western Colorado. Other low elevations will be in the 80s and 90s, ranging into the 50s and 60s for higher mountain locations. A couple isolated showers/weak thunderstorms are possible over the San Juan Mountains, Central Mountains, and Southeast Mountain regions, but they will produce more wind and lightning than rain. Maximum rain rates will be less than 0.2 inches/hour.

Timing: 1 PM – 8 PM

Issue Date: 6/19/2015
Issue Time: 9:38 AM

A MODERATE FLOOD THREAT CONTINUES FOR THE SOUTH PLATTE RIVER AND CACHE LA POUDRE RIVER. A LOW FLOOD THREAT CONTINUES FOR PORTIONS OF THE ARKANSAS RIVER. ADDITIONALLY, VARIOUS STREAMS/RIVERS CONTINUE TO RUN HIGH ACROSS WESTERN COLORADO.

The big story in today’s forecast will be the heat, as temperatures continue to climb over yesterday’s highs, bringing many low elevations into the 80s and 90s, and near 100 for the lowest valleys of Western Colorado. As temperatures also climb in the mountains, snowmelt will continue and streams/rivers will continue to run high. If you plan on being outdoors today, be careful near any flowing bodies of water. Saturated soils have made many banks unstable. Check with the local National Weather Service office for up-to-date warnings/advisories for areas you plan to visit.

A few isolated, afternoon/evening showers and thunderstorms will be possible, mainly over the higher terrain. Under westerly flow aloft, a storm or two will drift off of the mountains and over lower elevations, but gusty winds will be the main result. As you can see in the IPW graph below, the atmosphere is very dry across Colorado, so light rain will be about all storms can muster. The best chance for any measurable rainfall will be south of Highway 50, where moisture is slightly better. Even so, rain rates south of Highway 50 will max out around 0.4-0.6 inches/hour.

One area to watch will be the far Southeast Plains (Baca, Las Animas, Bent, Prowers, Kiowa, and Cheyenne counties) late this afternoon through the evening hours, as a dryline will set itself up across the region, with higher dewpoints just to the east. This will allow decent instability to take shape, and a few isolated thunderstorms are possible along this boundary. Without much help from wind shear, storms will be of the pulse variety if they can develop, coming down nearly as quickly as they go up. Brief moderate-to-heavy rain will be possible under these storms, with maximum rain rates of 0.8-1.2 inches/hour.

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, Urban Corridor, Palmer Ridge, and Northeast Plains:

Mostly sunny and hot is the main story today. Isolated showers/weak thunderstorms are possible late this afternoon over the Front Range, and then drifting eastward over the other regions. The main impacts from activity will be locally gusty winds and lightning, as storms will only muster light rain. Rain rates will be 0.10-0.25 inches/hour.

Timing: 2 PM – 10 PM

Southeast Plains, and Raton Ridge:

Mostly sunny and hot, with temperatures climbing into the 90s. Lower locations in the Arkansas River valley will reach near 100. A few isolated showers and thunderstorms will develop this afternoon/evening, resulting in mainly gusty winds, lightning, and light rainfall. The strongest storms will be capable of producing rain in the 0.8-1.2 inches/hour range over the far Southeast Plains late this afternoon/evening.

Timing: 2 PM – Midnight

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

Isolated showers/weak thunderstorms over the San Juan Mountains, Southeast Mountains, and Central Mountains; it will be sunny and dry elsewhere. With the dry atmosphere, any activity will result in gusty winds and some lightning, with sprinkles/light rain to the tune of 0.10-0.25 inches/hour being the best they can produce.

Timing: Noon – 7 PM