FTB 09-30-2016: Moisture Spreading Eastward

Issue Date: 9/30/2016
Issue Time: 10:03 AM

NO FLOOD THREAT IS FORECAST.

REMINDER: THIS IS THE FINAL FTB OF THE 2016 SEASON. IT HAS BEEN A PLEASURE TO SERVE YOU. THE NEXT FTB SEASON BEGINS ON MAY 1, 2017.

The moisture plume that has been laying across western Colorado for a couple of days now is on the move eastward, evidenced in the IPW chart below. Grand Junction IPW (green line) remains elevated, at around 1 inch, while Boulder (blue line) and Schriever AFB (pink line) are on a steady march upward. All in all, there will be plenty of moisture to fuel another period of scattered showers/isolated thunderstorms across much of the High Country and Western Slope, with lesser amounts of activity spilling over the Urban Corridor, and western extents of the Southeast Plains, Palmer Ridge, and Raton Ridge. Generally speaking, areas east of a north-south line from Sterling-to-Flagler-to-Las Animas-to-Andrix will remain dry.

ipw_20160930

Most activity will be in the form of showers, with light-to-moderate rainfall being the main impact. A couple isolated thunderstorms will mix in, producing periods of moderate rainfall, perhaps brief bouts with localized heavy rainfall. Area burn scars such as Waldo Canyon and Hayden Pass should be monitored, but no flood threat is warranted due to dry antecedent conditions. Additionally, localized street ponding may be an issue on roadways, so be on the lookout for that, as well. For more information, including rain rates and timing, please see the zone-specific discussions 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, jump below the map.

Flood Threat Legend

Zone-Specific Forecasts

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

Scattered showers and a couple embedded thunderstorms are expected, with the most activity focused along and east of I-25. Isolated showers/thunderstorms will spread a bit further eastward, west of a north-south line from Sterling-to-Flagler-to-Las Animas-to-Andrix. East of this line, conditions are expected to remain dry, with more clouds than during previous days. Most rain rates will be light underneath showers, with efficient rainfall coming from more organized activity. Maximum rain rates are as follows:

Urban Corridor and Palmer Ridge: 0.6-0.8 inches/hour
Southeast Plains and Northeast Plains: 0.4-0.7 inches/hour
Raton Ridge: 0.3-0.6 inches/hour

Timing: 11 AM – 11 PM

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

Scattered-to-numerous showers, and a few thunderstorms are expected, producing mainly light-to-moderate rainfall and gusty winds. One or two stronger thunderstorms will produce localized heavy rain, resulting in ponding on roadways and in low-lying areas. No flood threat is warranted as storm motions should keep activity moving at a decent clip, minimizing the threat from heavy rain. Maximum rain rates are as follows:

Southwest Slope and Grand Valley: 0.6-0.8 inches/hour
San Juan Mountains, Central Mountains, Northwest Slope, Northern Mountains, and Southeast Mountains: 0.4-0.7 inches/hour
Front Range: 0.5-0.9 inches/hour
San Luis Valley: 0.3-0.5 inches/hour

Timing: 11 AM – 9 PM for areas west of the Continental Divide, 11 AM – 1 AM for areas along and east of the Continental Divide