STP 06-29-2017: Isolated Showers with Limited Rainfall

Issue Date: Thursday, June 29. 2017
Issue Time: 10:00AM MDT

Isolated, high-based showers over the Northeast Plains, Palmer Ridge and Southeast Plains occurred again yesterday. Marginal low-level moisture limited the rainfall from the storms that developed along the KS/NE borders. CoCoRaHS stations in Kit Carson and Cheyenne Counties had rainfall just over 0.5 inches and Burlington- Kit Caron County Airport (KITR) recorded 0.8 inches. Rainfall amounts in the storm cores looked to be just over 1 inch. The main features of these storms were gusty winds. KITR reported a gust of 30mph as thunderstorms passed through the area.

West of the Continental Divide, very dry and windy conditions continued yesterday. Strong westerly winds with gusts up to 30mph were reported throughout the day and into the evening. Temperatures continued to be 5-10F above climatology.

The persistent pattern of weather the last two weeks can be very well seen in a cumulative precipitation map. East of the Continental Divide, there has been little moisture, and therefore almost no rainfall. West of the Divide, isolated showers have developed over the higher terrain almost every afternoon. Coupled with higher moisture, these storms have brought consistent rainfall to the Northeast and Southeast Plains.

Flooding was not reported on Wednesday. Please see the STP map below for a look at 24-hour precipitation totals.

Storm Total Precip Legend

FTB 06-28-2017: A Few Severe Storms Out East; Extreme Fire Danger West

Issue Date: Wednesday, June 28th, 2017
Issue Time: 11AM MDT

— Flooding is NOT expected today
Extreme fire danger for western Colorado

There will continue to be contrasting weather stories across our state today, where the weather never ceases to amaze. Regarding rainfall chances, a marginal amount of low-level moisture will hold on during the afternoon and evening hours along the KS/NE borders, which combined with favorable shear profiles could produce severe storms. Large hail, gusty winds and a tornado threat will be in the realm of possibilities today. Very short-duration heavy rainfall will be possible, but flooding is NOT expected.

Perhaps the bigger story, however, will be the extreme fire danger in the western part of the state where low relative humidity (see water vapor image below), gusty winds and hot temperatures will create a dangerous situation for spreading fires. Hikers/campers – please be cautious.

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.

Zone-Specific Forecasts:

Northeast Plains, Southeast Plains:

Partly cloudy with isolated to scattered thunderstorms possible after noon. Max 30 minute rainfall up to 0.8 inch and max 1-hour rainfall up to 1.2 inches will be just under flood intensity; thus no threat is issued. However, severe weather will be possible, including hail up to 2.5 inches, gusty winds up to 70 mph and an isolated tornado.

Primetime: 2PM to 11PM

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

Sunny early then partly cloudy with an isolated shower or perhaps a weak thunderstorm possible during the afternoon before the boundary layer mixes out. Max 30-minute rainfall 0.3 inches. Flooding is not expected today.

Primetime: 1PM to 8PM

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

Mostly sunny and hot today. An isolated shower or weak thunderstorm cannot be ruled out over higher terrain near the WY border. Max 1-hour rainfall up to 0.2 inches. Gusty winds and dry lightning will be more of a threat than rainfall. An extreme fire danger exists today, with a Red Flag warning in effect for most of the area. Please stay tuned to local National Weather Service offices for updates.

 

Primetime: 11AM to 7PM

STP 06-28-2017: Gusty Winds both East and West of the Continental Divide

Issue Date: Wednesday, June 28, 2017
Issue Time: 10:15AM MDT

Strong westerly flow aloft limited the amount of moisture available for thunderstorms in the High Country, Northeast Plains and Southeast Plains. Below, the low dew point temperatures show the lack of moisture at 4 pm MDT yesterday. West of the Continental Divide, the dew points were in the teens. Downward mixing of the strong upper level winds created gusty conditions on the Western Slope. A wind gust of 51mph was reported in Mack, CO at 1:30PM MDT.

A north/south dry line formed east of the Continental Divide in the afternoon limiting moisture to the Northeast/Southeast Plains. Denver recorded a 43F dew point early in the morning, and it had dropped to 29F by the afternoon. The drop in moisture from the previous days along the CO/KS border caused thunderstorms to produce gusty outflows and little rain. Outside Burlington, a 59mph gust outflow from a thunderstorm was reported at 9pm. Rainfall estimates (below) were around 0.25 inches to 0.60 inches with most storms and up to 1.75 inches under the small storm cores. CoCoRaHS data has the highest recorded rainfall amount in the northeast corner of Cheyenne County at 0.39 inches. This is in an area were rainfall estimates are in the range of 0.50 and 0.90 inches, so the radar rainfall estimates may be too high due to both dry sub-cloud air and hail contamination.

 

No flooding occurred yesterday. Please see the STP map below for a look at 24-hour precipitation totals.

Storm Total Precip Legend

FTB 06-27-2017: Substantial Drying Today, But A Few Strong-to-Severe Storms Possible East

Issue Date: Tuesday, June 27th, 2017
Issue Time: 10:50AM MDT

— Flooding is NOT expected today

After several days of elevated moisture across eastern Colorado, this morning’s water vapor imagery, below, suggests drying will overtake most of the state. This is courtesy of an approach disturbance that is causing lifting motion and showers/storms across WY and MT. For Colorado, however, the dry air will be the stronger hand today. Although isolated to scattered storms will be possible, especially across the higher terrain as well as eastern Colorado, rain rates will be below flood-threat intensity. Thus, flooding is not expected today.

In the far northeast corner of Colorado, severe weather will be possible later this afternoon as an incoming jet streak creates a favorable shear profile for strong, rotating updrafts. Large hail, up to 2.5 inches and gusty winds will be the main threat. Storm motions will be 30mph or greater, limiting heavy rainfall in a given locale.

Today’s precipitation probability map is shown below.

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.

Zone-Specific Forecasts:

Northeast Plains:

Sunny early then partly cloudy with isolated to scattered thunderstorms possible after noon. Max 30 minute rainfall up to 1 inch and max 1-hour rainfall up to 1.4 inches will be just under flood intensity; thus no threat is issued. However, severe weather will be possible, including hail up to 2.5 inches and gusty winds up to 65 mph.

Primetime: 2PM to 9PM

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

Sunny early then partly cloudy with isolated showers and perhaps a weak thunderstorm during the afternoon. Max 30-minute rainfall 0.5 inches. Flooding is not expected today.

Primetime: 12PM to 8PM

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

Mostly sunny and slightly cooler today. An isolated shower or weak thunderstorm will be possible especially over northern areas and higher elevations. Max 1-hour rainfall up to 0.4 inches. Gusty winds and dry lightning will be more of a threat than rainfall.

Primetime: 11AM to 7PM