FTB 07-11-2019: Hot Temperatures with a Chance of Thunderstorms over Southern Colorado

Issue Date: Thursday, July, 11th, 2019
Issue Time: 9:40AM MDT

–Flooding is NOT expected today

The upper level high pressure ridge remains centered over Colorado today and now covers most of the United States as the summer heatwave continues.  The clockwise rotation around the zone of high pressure (marked “H” below) will bring in moisture from the southwest, but keep the northern areas of the state mostly dry.  PW was measured at 1.12 and 0.64 inches over Tuscon and Flagstaff Arizona this morning and will move in from the south southwest throughout the day.  A shortwave embedded within the high pressure, marked by an X in the water vapor imagery below, is forecast to move over central Colorado by 2PM today.  This shortwave is expected to create a vorticity maximum over the area that will move to the southeast throughout the afternoon and into the night.  Thunderstorms are forecast over the southern half of the state, but insufficient deep moisture and weak upper level dynamic forcing will keep rainfall totals low.

Riverine: As of 9:30AM there are no NWS Flood Warnings or Flood Advisories.  The AHPS gage on the Arkansas River near La Junta retreated below action stage yesterday around noon but the gage on the Rio Grande near Alamosa remains at Action Stage.  Most rivers have seen a gradual decrease in flow this week due to dry conditions.

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:

Southwest Slope, San Juan Mountains, San Luis Valley, Central Mountains, Front Range, Southeast Mountains, Raton Ridge, Southeast Plains, Palmer Ridge

Midlevel moisture will increase over the region today, however low level and surface moisture remains low.  Afternoon and evening thunderstorms can be expected over the area.  A surface low is expected to form over the southern Front Range and Southeast plains by 3PM.  This feature will provide lift for storms over the Southeast Plains and Raton Ridge, with max 1-hr rainfall rates of 0.7 inches over the area.  Max 1-hr rainfall rates of 0.2 inches is forecast over the mountainous regions of the forecast area.  Flooding is not expected today, with the main threat being isolated wind gusts up to 30 mph.  High temperatures are forecast to reach 100°F over the eastern plains and low laying areas of the western slope.  Please use caution outdoors and stay hydrated.

Primetime: 1PM to 1AM

Grand Valley, Northwest Slope, Northern Mountains, Urban Corridor, Northeast Plains

The forecast area is expected to remain dry today, with chances for weak isolated thunderstorms over the higher elevations.  Storms may move into the southern Northeast Plains off of outflow boundaries from storms over the Southeast Plains.  Max 1-hr rainfall rates of 0.3 inches are possible over the Northeast plains, with max 1-hr rainfall rates of 0.1 inches over the high country.  High temperatures may reach 100°F today over the Northeast Plains and Urban Corridor, with highs in the upper 80°Fs and low 90°Fs over the valleys of the high country.  Please use caution and stay hydrated if you are outdoors.

Primetime: 7PM to 12AM