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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – April 13, 2018

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

Forecast Discussion:

Since this storm is rolling in Thursday PM - I'm posting the Friday discussion a 1/2 day early to cover this front. AND there is a chance of snow is now possible!! (Don't get the shovels or sleds out though.)

But first, where are we with the snowpack (this has been out on twitter today)?  Figure 1 is the snowpack in dark blue (with the 'you are here' arrow) for Colorado overall.  We are above where we were in 2015 (green line) but below normal stukk. Our last storm (with the prolonged moist westerly flow) was helpful!

The winds in Longmont were delayed until later in the afternoon.  The high wind warning and fire danger were expected to expire at 9pm Thursday. Figure 1 shows those mountain and foothill winds and the blue arrow gives direction (also seen in the thin grey lines with arrows on them; streamlines).

Figure 2 shows the temperature anomaly map with an approximate location of the front midnight Thursday. Figure 3 has the front past us (and might actually be almost to Kansas in reality). Temperatures are dropping Friday by sunrise.  By noon today (Friday)- much colder air is in place- state wide (the front is way off to the east and southeast) - Figure 5.

The good news is that, even though down slow flow will keep us pretty dry, enough lift and moisture should move in that we now get a coating to an inch of snow (Figure 6).  But it is not a lot of water (Figure 7) 0.05-0.25 inches - with the low end most likely.  You can see the good snow storm (with the wind--> blizzard conditions will be possible) way out near Nebraska in NE CO.

Figure 8 are the midday Friday winds, like Figure 2, and the powerful (sustained 25-30mph gusts to 50mph) north winds are still on tap for Longmont.  A wide area of the plains sits with 55mph sustained winds midday today (Friday).

Figure 1: the current snowfall (dark blue line) is compared to the average (bright red line) of the last 4 years. The prior 4 years are red, green, yellow and light blue) from, NRCS and SNOTEL.

Figure 2: GFS forecast surface pressure (black lines), streamlines (grey lines with arrows) and wind speeds (color gradients) for noon Thursday (yes, yesterday). From weather5280.com.

Figure 3: the GFS forecast surface temperature anomaly (departure from normal) for Friday PM. The blue line is an approximate location for the incoming front/wind shift direction. Longmont is the pink dot. From weather5280.com.

Figure 4: the GFS forecast surface temperature anomaly (departure from normal) for Friday AM. The blue line is an approximate location for the incoming front/wind shift direction. Longmont is the pink dot. From weather5280.com.

Figure 5: the GFS forecast surface temperature anomaly (departure from normal) for Friday noon. The blue line is an approximate location for the incoming front/wind shift direction. Longmont is the pink dot. From weather5280.com.

Figure 6: the GFS forecast total snowfall estimate from Thur PM to Saturday AM From weather5280.com.

Figure 7: the GFS forecast total precipitation estimate from Thur PM to Saturday AM From weather5280.com.

Figure 8: GFS forecast surface pressure (black lines), streamlines (grey lines with arrows) and wind speeds (color gradients) for Friday PM. From weather5280.com.

The longer range forecast:

We warm rapidly to almost 80F again on Monday.  Our next chance of rain is Friday/Saturday at the end of the upcoming week.  More on that later!

Current Weather

Sunny

Sunny

63°F

UV Index
6 High
Pressure
29.82 Falling
Visibility
7 miles
Dewpoint
47 °F
Humidity
58%
Wind
NE 1.7 mph
Gust
4.3 mph
Wind Chill
63 °F

Hourly Forecast

Today
11 AM
68°F
Partly sunny
Today
12 PM
73°F
Intermittent clouds
Today
1 PM
77°F
Intermittent clouds
Today
2 PM
76°F
Cloudy
Today
3 PM
75°F
Cloudy
Today
4 PM
73°F
Cloudy
Today
5 PM
70°F
Cloudy
Today
6 PM
68°F
Cloudy
Today
7 PM
65°F
Cloudy
Today
8 PM
62°F
Thunderstorms
Today
9 PM
59°F
Cloudy
Today
10 PM
56°F
Cloudy

7 Day Forecast

Mostly cloudy

Thursday

77 °F

Turning cloudy; warm


Thunderstorms

Thursday Night

47 °F

A thunderstorm in spots this evening; otherwise, considerable cloudiness


Thunderstorms

Friday

70 °F

Mostly cloudy and not as warm with a couple of thundershowers


Thunderstorms

Friday Night

43 °F

Cloudy with a couple of thundershowers


Rain

Saturday

46 °F

Chilly with periods of rain and a thunderstorm


Rain and snow

Saturday Night

39 °F

Cloudy with rain, mixed with a little snow late


Mostly cloudy

Sunday

59 °F

Mostly cloudy and warmer; a stray afternoon thundershower


Partly cloudy

Sunday Night

36 °F

Partly cloudy


Partly sunny

Monday

71 °F

Partly sunny and warmer


Partly cloudy

Monday Night

39 °F

Partly cloudy


Sunrise and Sunset

Sunrise
6:07 AM
Sunset
7:50 PM

Based on AccuWeather data