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3pm Wed. Update: Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – August 14-15, 2019

This content was originally published by the Longmont Observer and is licensed under a Creative Commons license.

In Brief:

After a possible round of strong later night storms Tuesday PM, we'll have warm to hot weather and afternoon storms most days this week. Severe weather chances are just to our east and may get bumped any day back to include I-25 folks. Keep aware!

3pm Update:

The NWS and high resolution models were correct and the outflow from the storms, that formed to the distant east earlier in the day Tuesday, hit the Front Range late in the evening and triggered hail producing storms. My rain gauge picked up under 1/10th of an inch of rain.

There were hail, tornado, and high wind reports in Colorado and just over the line into Kansas yesterday. Longmont is the big pink dot (Figure 1 update).

A similar situation is occurring again today (Wednesday) but the outflow boundary headed for us this evening is not expected to be able to trigger activity this time (due to moisture levels and the vertical temperature structure of the atmosphere).

Figure 1 update: the SPC storm reports up to 7am Wednesday.

End 3pm Update.

Forecast Discussion:

There was some rich, shallow, moisture east of a dryline that formed east of Longmont Tuesday. This situation will keep repeating each day for the next few days (Figure 1). The High Resolution Rapid Refresh model (HRRR) and others are predicting some strong storms to form - yet - Tuesday night. The HRRR (Figure 2) has 2/3rds of an inch hit the town tonight and the weatherunderground model is very similar (green arrow in Figure 3). We'll see, but the NWS is expecting it too.

For Wednesday, we have a repeat that may be not as severe for the state (there was record breaking hail and a number of tornadoes out on the eastern Plains Tuesday). The severe chances are close - a Marginal Risk is maybe 50 miles to the east (Figure 4).

The Longer Range Forecast:

We see 90'sF continue, severe storms nearby (Thursday's Marginal Risk to our east is seen in Figure 5). The fine details will be better seen a day or two out as the week goes on.

Figure 1 update: the water vapor satellite image (browns/reds are dry air, whites and light grey is moist air, purple/blue is ice and high cloud tops). From the the Weather Channel from Tuesday PM.
Figure 2: The HRRR model 15 hour precipitation forecast up to 9am Wednesday from weather5280.com
Figure 3: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 4: The severe storm weather forecast for the U.S. from the Storm Predication Center in Norman, OK. Made Tuesday for Wednesday.
Figure 5: The severe storm weather forecast for the U.S. from the Storm Predication Center in Norman, OK. Made Tuesday for Thursday.



Comments

Clear

Clear

63°F

UV Index
0 Low
Pressure
30.31 Rising
Visibility
10 miles
Dewpoint
45 °F
Humidity
51%
Wind
WNW 3.5 mph
Gust
5.5 mph
Wind Chill
63 °F

Forecast


Sunny

Friday

100 °F

Sunny; caution advised if outside for extended periods of time


Partly cloudy

Friday Night

63 °F

Partly cloudy


Mostly sunny

Saturday

94 °F

Mostly sunny and very warm; air quality will be unhealthy for sensitive groups


Mostly clear

Saturday Night

60 °F

Mainly clear; air quality will be unhealthy for sensitive groups


Partly sunny w/ t-storms

Sunday

98 °F

Very warm with partial sunshine; a shower or thunderstorm in spots in the afternoon


Partly cloudy w/ t-storms

Sunday Night

65 °F

A shower or thunderstorm in spots in the evening; otherwise, mainly clear and mild


Partly sunny

Monday

96 °F

Remaining very warm with some sun


Mostly clear

Monday Night

58 °F

Mainly clear


Partly sunny

Tuesday

88 °F

Not as hot with sun and some clouds


Partly cloudy w/ t-storms

Tuesday Night

58 °F

A couple of thunderstorms around in the evening; otherwise, patchy clouds


Sunrise and Sunset

Sunrise
11:41 AM
Sunset
2:31 AM

Based on AccuWeather data