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Sun Update: Front Range Forecast: Storms now, summer this week

In Brief:

Storm chances for one more day, then summer weather returns.

Sunday update:

Ample moisture and northwest flow brining in short waves aloft will kick off storms through Monday (Figure 1 update).  The ridge center wanders towards our state for the rest of the week with above normal temperatures and only afternoon storm chances. 

figure1u_08272023

End Sunday update.

Thursday update:

Flood Watch

Issued: 1:54 PM Aug. 24, 2023 – National Weather Service

...FLOOD WATCH IN EFFECT FROM FRIDAY MORNING THROUGH SATURDAY
MORNING...

* WHAT...Flash flooding caused by excessive rainfall is possible.

* WHERE...Portions of central, east central, north central, and northeast Colorado, including the following areas, in central Colorado, Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below 9000 Feet. In east central Colorado, North and Northeast Elbert County Below 6000 Feet/North Lincoln County. In north central Colorado, Larimer County Below 6000 Feet/Northwest Weld County and Larimer and Boulder Counties Between 6000 and 9000 Feet. In northeast Colorado, Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County, Central and East Adams and Arapahoe Counties, Central and South Weld County, Elbert/Central and East Douglas Counties Above 6000 Feet, Logan County, Morgan County, North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County, Northeast Weld County, Phillips County, Sedgwick County and Washington County.

* WHEN...From Friday morning through Saturday morning.

* IMPACTS...Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Flooding may occur in poor drainage and urban areas.

* ADDITIONAL DETAILS...
- Slow moving thunderstorms are forecast to develop late Friday morning and continue through Friday night and early Saturday. Heavy rain is likely with these storms. Localized rainfall totals in excess of 3 inches are possible where training storms develop.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued.

 

End Thursday update.

The Forecast Discussion:

Wednesday and Thursday will still sport summer weather with low rain chances (Figure 1). A cold front arrives early Friday AM and temperatures drop to far below normal and the front brings back fairly widespread rain chances (Figure 2) Friday and Saturday (Figure 3).  The NWS even thinks locally heavy rain and flash flooding will be possible Saturday.

figure1_08232023
Figure 1: the 10 day graphical forecast for Denver from weatherunderground.com
figure2_08232023
Figure 2: the surface pressure and precipitation forecast from the GFS and tropicaltidbits.com for Friday noon.
figure3_08232023
Figure 3: the NWS surface map forecast for Saturday AM from NOAA.

The Longer Range Forecast:

We remain cool for the start of the week with another shot of rain Sunday/Monday (Figure 1). Temperatures will hover around normal next week.

The weatherunderground model (Figure 1) thinks we could get almost 1.5 inches of water over the next week. The GFS gives Longmont a rainfall total more like 0.5 to 0.75 inch of water. A taste of Fall?!?!

figure4_08232023
Figure 4: the 5 day precipitation forecast from the GFS and weather5280.com

 


About the Author: John Ensworth

John Ensworth used to work from Longmont as the PI for the NASA through the IGES (The Institute for Global Environmental Strategies). He now teaches technology, algebra, astronomy, meteorology, film school, and Lego robotics to middle/high school.
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Current Weather

Sunny

Sunny

67°F

UV Index
5 Moderate
Pressure
30.08 Steady
Visibility
7 miles
Dewpoint
44 °F
Humidity
44%
Wind
ENE 2.3 mph
Gust
4.9 mph
Wind Chill
67 °F

Hourly Forecast

Today
10 AM
72°F
Mostly sunny
Today
11 AM
74°F
Mostly sunny
Today
12 PM
77°F
Partly sunny
Today
1 PM
79°F
Partly sunny
Today
2 PM
80°F
Intermittent clouds
Today
3 PM
81°F
Intermittent clouds
Today
4 PM
79°F
Intermittent clouds
Today
5 PM
76°F
Mostly cloudy w/ t-storms
Today
6 PM
73°F
Intermittent clouds
Today
7 PM
70°F
Intermittent clouds
Today
8 PM
67°F
Partly sunny
Today
9 PM
63°F
Partly cloudy

7 Day Forecast

Partly sunny w/ t-storms

Thursday

81 °F

Clouds and sunshine with a thunderstorm this afternoon


Partly cloudy

Thursday Night

48 °F

Partly cloudy


Partly sunny w/ t-storms

Friday

75 °F

Partly sunny with a strong thunderstorm in spots late in the afternoon


Partly cloudy

Friday Night

49 °F

Partly cloudy


Intermittent clouds

Saturday

83 °F

Times of sun and clouds


Mostly clear

Saturday Night

51 °F

Mainly clear


Intermittent clouds

Sunday

93 °F

Hot with the temperature breaking the record of 91 set in 2020 with intervals of clouds and sun; breezy in the afternoon


Mostly clear

Sunday Night

54 °F

Mainly clear


Mostly cloudy

Monday

92 °F

Turning cloudy and hot with the temperature approaching the record of 95 set in 2006


Intermittent clouds

Monday Night

60 °F

Clouds breaking; mild


Sunrise and Sunset

Sunrise
5:34 AM
Sunset
8:23 PM

Based on AccuWeather data