FTB 09-23-2018: More heat with Evening Rain in the Northwest

Issue Date: Sunday, September 23rd, 2018
Issue Time: 09:15  AM MDT

 — Flooding is NOT expected today

With high pressure continuing over Colorado today, more hot and dry air is being advected into the state from the southwest. This, again, will leave most of the state with warmer than average temperatures today and very fair skies. Dewpoints will continue to be low compared to how hot afternoon temperatures will be: generally in the 20s and 30s F with afternoon high temperatures in the mid- to upper-80s. This will stifle much of the afternoon cloud development and any precipitation that might form. These low humidity values as well as increasing afternoon winds will spell elevated fire weather danger across Colorado. Wildfires, like the 3,000-acre Ryan Fire in Jackson County, will continue to grow today in the northern section of the state as wind speeds pick up.

As the afternoon fades into evening, a small upper-level shortwave will push into the northwest part of Colorado. The Northwest Slope overnight will see rainfall as dewpoints elevate and surface air is lifted as it encounters the foothills and peaks of the Northern Mountains. This change of weather will affect the entire state in the days to come, hopefully quelling fire conditions into the work week. No flooding is expected 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:

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

More hot and dry weather today as the upper level trough continues its hold on Colorado east of the divide. Low dewpoints will mean mostly clear skies, and daytime high temperatures will be in the mid- to upper-80s across the plains and the Palmer Ridge, Raton Ridge, and Urban Corridor, and in the 70s in the mountainous areas. No rain is forecast today, making for a great Sunday to get out and enjoy the warm weather.

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

Some lingering morning clouds are dissipating, and the western portions of Colorado will experience a sunny and very warm day, with temperatures in the mid-70s in the Northwest Slope and the mountainous regions, and in the 80s in the Southwest Slope and the San Luis Valley. A shortwave moving across Utah and Southwest Wyoming will enter the Northwest Slope overnight. Rain showers and occasional thunderstorms will move through the Nortwest Slope and the Northern Mountains, with rainfall rates generally below 0.25 inches per hour. Interaction with the Northern Mountains could bring brief periods of rainfall near 0.5 inches per hour. These more intense showers could fall very close to the Beaver Creek burn scar in Jackson County, but flooding here is not anticipated.

Primetime: midnight-6AM

FTB 09-22-2018: Warm and Dry for the First Day of Fall

Issue Date: Saturday, September 22nd, 2018
Issue Time: 09:00AM MDT

 — Flooding is NOT expected today

Today marks the autumnal equinox and the official start of astronomical fall, and for Colorado a broad upper-level ridge that has been slowly building and moving its way east off of the Pacific Coast will entrench itself above the state. At the surface, this will bring high pressure and fair weather to across the state as we begin the morning with clear skies and cool temperatures. Indeed, much like the last couple of days, the Northwest Slope and Grand Valley woke up to very chilly temperatures. Some valley areas in these regions saw overnight lows in the upper 20’s.

As the sun further rises, winds will gradually pick up out of the south, and – despite chilly morning temperatures – temperatures in the late morning and through the afternoon will be warmer than average, making for a sunny and pleasant first day of fall. The dry and warm southerly air will have some drawbacks, however, with a lingering threat of fire weather. Luckily, wind speeds will not pick up enough to warrant a Red Flag Warning any part of the state, save for the northwest part of Moffat County in the Northwest Slope. No flooding is expected for 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:

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

A sunny and clear start to the morning, with relatively calm and variable winds across the plains and through the mountains east of the great divide. Dewpoints will struggle to get above 40 degrees F today, except for a north-south slot from western Animas up through Huerfano, Pueblo, and El Paso counties. Here, dewpoints may reach as high as 50 degrees, but with virtually no mechanism to lift this moisture aloft, there will be very little chance for afternoon cloud build-up, let alone any precipitation. Afternoon temperatures throughout the eastern plains areas and the Urban Corridor will be in the mid-80s, and further west along the Front Range expect afternoon highs in the 70s.

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

Another chilly and clear start to the morning, with valley areas reaching below freezing overnight, especially in the Northwest Slope. As the high pressure builds throughout the state during the day, winds will be light and generally from the south. Expect temperatures in the low 80s and light winds in the Northwest and Southwest Slope regions and upper 60s/lower 70s in the mountainous regions with slightly windier conditions. No precipitation is forecast today, and while the vast majority of the region is not within a Red Flag Warning, fire weather potential is still elevated today due to the warm and dry temperatures.

FTB 09-21-2018: Morning Upslope Showers for the Southeast Mountains and Raton Ridge

Issue Date: Friday, September 21st, 2018
Issue Time: 08:55AM MDT

 — Flooding is NOT expected today

Taking a look at the visible satellite imagery below, there are some moderate showers and cloud cover over the Southeast Mountains and Raton Ridge this morning. These upslope showers fired earlier this morning after the passage of a secondary cold front. Isolated showers are expected through noontime before drier air works its way in from the west. There is also some low cloud cover over the northern Urban Corridor, but this will quickly burn off with the morning heating. Temperatures overnight dropped very low with efficient radial cooling due to mostly clear skies. Highs this morning over the plains were in the 40Fs with low 30Fs over the Northwest Slope. This likely means that some of the mountain valleys dropped into the 20Fs. Expecting similar lows tonight even though high temperatures today will be slightly above normal. Perfect timing for these large diurnal temperature swings since fall officially begins tomorrow.

Today the ridge in the image below will begin to slide east as the 500mb high works its way to the NM/AZ border. This means higher heights will build over the state, which will bring calmer weather. The 500mb high will set the stage for WSW winds aloft, and with the 500mb high moving east, moisture should remain to our south and east as well. The WSW winds will entrain a dry air mass from Utah and Arizona, both of which are cloud free at this moment. So outside of morning showers over the Raton Ridge and Southeast Mountains, not expecting measureable rainfall this afternoon. There will be enough moisture for some high clouds and an isolated high-based showers or two near the Continental Divide this afternoon. These storms will likely produce sprinkles and brief winds though minor accumulations are possible. Flooding is not expected 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:

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

Some moderate upslope showers are present over the Southeast Mountains and Raton Ridge. These showers fired early this morning in the wake of a secondary cold front. Expecting these storms to last until noontime with max totals up to 0.25 inches. WSW flow will begin to entrain a drier air mass this afternoon, and with rising heights, not expecting much rainfall this afternoon. The dry air should also begin to break up the clouds over the Southeast Mountains and adjacent plains throughout the day. More afternoon cloud cover will be likely over the higher terrains near the Continental Divide, and an isolated high-based shower or two is possible. Though these storms may produce brief rain, not expecting totals over 0.1 inches.

Primetime: 9AM to 8PM

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

Drier air continues to be entrained from the WNW as the ridge builds over the area today. Without the jet influencing surface winds today, we should get a brief break in fire weather. Surface wind speeds today should remain around 5mph, though there is a fire weather watch for the Northwest Slope on Saturday and Sunday. This afternoon increased cloud cover is likely over the southern high terrains near the Continental Divide, so there may be an isolated shower or two. Totals up to 0.1 inches are possible. Morning temperatures were quite low, but expecting high temperatures to reach the mid-70Fs at the lower elevations and 60Fs over the mountains. Grand Valley high temperatures are forecast to reach the mid-80Fs.

 

FTB 09-20-2018: Showers and Thunderstorms Continue over Eastern Colorado as the Trough Travels East

Issue Date: Thursday, September 20th, 2018
Issue Time: 09:20AM MDT

— Flooding is NOT expected today

Finally some fall weather to start the day as we near the end of September. Overnight and morning showers are producing lots of cloud cover over the mountains and eastern Colorado. There were even reports of snow over 11,000 feet last night. Temperatures have dropped to more seasonal values in the wake of the cold front, which is very much welcomed after the last heat wave. The main axis of the trough (and moisture) will continue to move eastward today, which means the line of showers will travel eastward as well. That should bring some stronger showers and thunderstorms to the southeast corner of the state and eastern Raton Ridge early this afternoon. Light showers and weaker thunderstorms will be possible over the eastern plains north of Prowers County. A bit of moisture is also able to hold on over the far northeast corner of the state. A surface low in the area is expected to produce a line of convergence on its northeast side, so some isolated thunderstorms will be possible near the NE/CO border.

Behind the trough, much drier air will work its way into the state with WNW flow aloft as evidenced by clear skies over the Utah/Colorado border. Dew points are forecast to quickly drop off starting this morning, so expecting clouds to clear west to east as the dry air mass moves eastward. The clearing skies will also allow temperatures to the west to begin to increase, so it should be a beautiful afternoon and evening. The entrainment of the dry air will limit rainfall chances over the higher terrains this afternoon though a couple isolated high-based showers possible. Storms that do initiate will likely form along the southern Continental Divide, but totals will remain under 0.1 inches. The Southeast Mountains will get a bit more rainfall today as the moisture plume is still over this region. These storms should end as the plume moves east by early afternoon. Flooding is not expected today.

As the trough passes to the north today, increased surface winds are anticipated over the northern third of the state. With dew points dropping off rapidly, enhanced and possibility critical fire weather will be present this afternoon through this evening. Surface wind speeds are forecast to be in the 15 to 25mph range with gusts up to 40mph possible over the higher terrains.

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:

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

Drying will occur from west to east today as the trough passes through the area. This should bring some clear skies to the west later this morning and afternoon. The stronger showers and thunderstorms today should be confined to the far eastern plains though some weaker storms will be possible over the Southeast Mountains and Raton Ridge as the line of convection moves eastward. Max 1-hr rain rates up to 0.5 inches will be possible over the Raton Ridge. Stronger thunderstorm activity is forecast over the southeast corner of the state where some decent instability is able to build. Fairly quick steering winds should keep totals from reaching flood threat criteria. Max 1-hr rain rates up to 1.25 inches with small hail and gusty winds are possible. An isolated storm or two is also possible near the CO/NE border associated with a surface low. Max 1-hr rain rates up to 0.9 inches are possible with these storms along with small hail and gusty winds. Flooding is not expected.

Primetime: 10AM to 8PM

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

Drier air is being entrained from the WNW after the passage of the trough. Increased subsidence and low dew points should keep rainfall chances minimal today. It will be possible for some light, isolated showers over the higher terrains near the southern portion of the Continental Divide this afternoon. However, totals are expected to be under 0.1 inches with some brief wind possible, too. Surface winds will increase over the northern third of the state with the passing upper-level jet, so enhanced and possibly critical fire weather will be present in this region. Wind speeds are forecast to be in the 15 to 25 mph range with gusts up to 40 mph possible over the northern high terrains. Clear skies with the entrainment of the dry air will allow temperatures to increase this afternoon with highs over the lower elevations reaching 80F.  Flooding is not expected.

Primetime: 2PM to 7PM