The Weather Wire

 

April 2010                                                                                                            Volume 17 Number 04

 

Contents

 

 

 
·   Why So Windy
 

·   Drought Monitor

 

·   March

    Summary

 

·   March Stats

 

·   April Preview

 

·   Sunrise/Sunset

 

·   Snow Totals

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March

Avg High - 53.5

Avg Low - 28.5

Snow - 12.8"

Season Snow - 58.8"

Precipitation - 0.80"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

April

Avg High - 60.9

Avg Low - 34.2

Avg Snow -  9.1"

Avg Precip - 1.93"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Skyview Weather 

2350 N Rocky View Rd

Castle Rock, CO 80108

 

Phone: (303) 688-9175

Fax: (303) 380-3338

 

E-mail:    

tim@skyview-wx.com

 

We’re on the Web!

http://www.skyview-wx.com/

 

Copyright 2010

Skyview Weather

Why So Windy?

If you thought it has been windy recently, it has been!  The spring months are often the windiest time of year for many locations in Colorado.  The reason is simple, the change of seasons and the warming of the earth’s surface.  Winters grip still hangs on to the north while spring is in full swing to our south.  These warm and cold air masses duel it out over Colorado and result in large swings in temperature with very warm and dry days and periods of rainy/snowy weather with the first threat of severe storms.  These air masses are moved by the wind and the winds are strongest in areas with the tightest temperature gradient, or where cold and warm temperatures are separated by little distance such as a front.  This collision of warmer and colder air occurs often in the spring and results in numerous days during the months of March, April and early May being considered breezy or windy.  April is actually Denver’s windiest month of the year on average.  Below is a table that shows the average wind speed per month in Denver:

winds.jpg       

Notice how the windiest months are in the spring and the calmest months are in the fall.  The reason for the weaker winds in the fall is because the surface is now cooling resulting in a more stable atmosphere.  The rapid warming of the surface as compared to the slower warming atmosphere creates atmospheric instability.  This instability is caused by warmer air near the surface being warmer than the air around it which then begins to lift the parcel of air upwards.  If the warmer air rises with enough force, moisture and spin severe weather can develop which is why most of our tornadoes, large hail and strongest squall lines occur in the spring with more diurnal trends as we move into mid-summer. 

I don’t want anyone to forget about the strong windstorms that can occur adjacent to the foothills during the months of November through January as these famous wind storms have produced wind gusts in excess of 100mph.  This type of strong wind scenario is driven more by topography, stability and upper level winds and are confined to a smaller geographic region often not affecting areas east of I-25.  The springtime winds affect a much larger area and can last for a much longer period of time but their peak gusts are typically confined to the 45-60mph range and are most likely from the south or southwest and occasionally from the west.  

 Drought Update

With the widespread precipitation of the last several months few areas of drought remain over Colorado, though some dry areas have developed in western Colorado.

The map below shows forecasted temperature deviances for April 2010. As can be seen, normal temperatures are expected for much of the state, though the southwestern areas of the state are expected to have above normal temperatures.

The map below shows forecasted precipitation deviances for April 2010.  Virtually all of Colorado is expected to have above normal precipitation for the month..

Little in the way of drought remains in Colorado.

March Summary

March of 2010 did not disappoint in the snowfall department as there was some impressive monthly totals in the Denver area with 12.8" reported at DIA, but most areas of the city received between 15-30" of new snow for the month.  Precipitation was below normal at DIA, but this area does not represent the city very well and there were much higher precipitation totals most areas.  I cannot remember when we tied or broke a high temperature record this winter as it has been very cold for the most part but there was a record high of 82 on the 30th.  Temperatures in general were very close to normal with a monthly mean of 41.0 degrees which is 1.4 degrees warmer than the average of 39.6.  As far as Denver goes we don't need another snowflake to make this year above normal in the snowfall department so any additional snow will just add to the snow surplus.  Most of the snow in March came in two storms one on the 19-20th and another on the 23-24th. 

March Stats

TEMPERATURE (IN DEGREES F)

 

 

 

 

 

 

AVERAGE MAX

53.5

NORMAL

53.7

DEPARTURE

-0.2

AVERAGE MIN

28.5

NORMAL

25.4

DEPARTURE

3.1

MONTHLY MEAN

41.0

NORMAL

39.6

DEPARTURE

1.4

HIGHEST

82 on the 30th

LOWEST

13 on the 20th

 

 

 

 

 

 

DAYS WITH MAX 90 OR ABOVE

0

NORMAL

0

DAYS WITH MAX 32 OR BELOW

0

NORMAL

2.8

DAYS WITH MIN 32 OR BELOW

23

NORMAL

24.3

DAYS WITH MIN ZERO OR BELOW

0

NORMAL

0.5

 

 

 

 

 

 

TEMPERATURE RECORDS

 

New record high of 82 set on the 30th

 

 

 

 

 

 

 

HEATING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

737

NORMAL

788

DEPARTURE

-51

SEASONAL TOTAL

5544

NORMAL

5277

DEPARTURE

267

 

 

 

 

 

 

COOLING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

0

NORMAL

0

DEPARTURE

0

YEARLY TOTAL

0

NORMAL

0

DEPARTURE

0

 

 

 

 

 

 

PRECIPITATION (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

0.80

NORMAL

1.28

DEPARTURE

-0.48

YEARLY TOTAL

1.17

NORMAL

2.28

DEPARTURE

-1.11

GREATEST IN 24 HOURS

0.65" on 3/26-3/27

DAYS WITH MEASURABLE PRECIPITATION

6

 

 

 

 

 

SNOWFALL (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

12.8

NORMAL

11.7

DEPARTURE

1.1

SEASONAL TOTAL

58.8

NORMAL

53.6

DEPARTURE

5.2

GREATEST IN 24 HOURS

10.8" on the 23rd to 24th

GREATEST DEPTH

NA

 

 

 

 

 

 

WIND (IN MILES PER HOUR)

 

 

 

 

 

 

AVERAGE SPEED

10.0mph from the N

PEAK WIND GUST

47mph from the N on the 11th

 

 

 

 

 

 

MISCELLANEOUS WEATHER

 

 

 

 

 

 

NUMBER OF DAYS WITH THUNDERSTORMS

1

NORMAL

<1

NUMBER OF DAYS WITH HEAVY FOG

5

NORMAL

1

NUMBER OF DAYS WITH HAIL

0

 

 

PERCENT OF SUNSHINE

NA

NORMAL

69%

April Preview

April is typically the month where our last meaningful snows occur with 3 storms on average during the month.  Not surprising, but snow can fall heavily during this month and it is the 3rd snowiest month of the calendar year on average with 9.1".  High temperatures begin to warm up dramatically with average highs right around 60 degrees.  Average lows also warm significantly with 34.2 degrees, but the average last freeze/frost is not usually until the second or third week in May.  If it has felt windy lately it is because it has been and April is typically the windiest month of the year.  Almost any form of precipitation can occur during the month with rain, sleet, snow, hail, etc and there can even be some severe weather towards the end of the month.  Thunderstorms usually make an appearance this month but only a couple of days on average.  The weather pattern looks to be drying out for the short term and that will likely result in normal or slightly below normal snowfall for the month and average to above average temperatures.        

DENVER'S NOVEMBER CLIMATOLOGICALLY NORMAL

(NORMAL PERIOD 1971-2000)

 

 

TEMPERATURE

 

 

 

AVERAGE HIGH

60.9

AVERAGE LOW

34.2

MONTHLY MEAN

47.6

DAYS WITH HIGH 90 OR ABOVE

<1

DAYS WITH HIGH 32 OR BELOW

<1

DAYS WITH LOW 32 OR BELOW

11

DAYS WITH LOWS ZERO OR BELOW

<1

 

 

PRECIPITATION

 

 

 

MONTHLY MEAN

1.93"

DAYS WITH MEASURABLE PRECIPITATION

9

AVERAGE SNOWFALL IN INCHES

9.1"

DAYS WITH 1.0 INCH OF SNOW OR MORE

3

 

 

MISCELLANEOUS AVERAGES

 

 

 

HEATING DEGREE DAYS

524

COOLING DEGREE DAYS

2

WIND SPEED (MPH)

10.0mph

WIND DIRECTION

South

DAYS WITH THUNDERSTORMS

2

DAYS WITH DENSE FOG

1

PERCENT OF SUNSHINE POSSIBLE

67%

 

 

EXTREMES

 

 

 

RECORD HIGH

90 on 4/30/1002

RECORD LOW

-2 on 4/2/1975

WARMEST

56.4 in 1956 and 1981

COLDEST

38.8 in 1920

WETTEST

8.24" in 1900

DRIEST

0.03" in 1963

SNOWIEST

38.8 in 1933

LEAST SNOWIEST

0.0" 1888, 1930, 1943, 1992
 

Sunrise/Sunset (Jan - June Denver area)

             JAN              FEB               MAR              APR              MAY              JUN
_______________________________________________________________________________
      sr - ss     sr - ss     sr - ss     sr - ss     sr - ss     sr - ss 
 01  0721-0446 | 0707-0518 | 0632-0550 | 0544-0623 | 0600-0753 | 0534-0821  01
 02  0721-0447 | 0706-0519 | 0631-0551 | 0542-0624 | 0559-0754 | 0533-0822  02
 03  0721-0448 | 0705-0520 | 0629-0553 | 0540-0625 | 0558-0755 | 0533-0822  03
 04  0721-0448 | 0704-0522 | 0628-0554 | 0639-0726 | 0556-0756 | 0533-0823  04
 
 05  0721-0449 | 0703-0523 | 0626-0555 | 0637-0727 | 0555-0757 | 0532-0824  05
 06  0721-0450 | 0702-0524 | 0625-0556 | 0636-0728 | 0554-0758 | 0532-0824  06
 07  0721-0451 | 0701-0525 | 0623-0557 | 0634-0729 | 0553-0759 | 0532-0825  07
 08  0720-0452 | 0700-0526 | 0622-0558 | 0633-0730 | 0552-0800 | 0532-0825  08
 
 09  0720-0453 | 0659-0527 | 0620-0559 | 0631-0731 | 0551-0801 | 0531-0826  09
 10  0720-0454 | 0658-0529 | 0619-0600 | 0630-0732 | 0550-0802 | 0531-0827  10
 11  0720-0455 | 0657-0530 | 0617-0601 | 0628-0733 | 0549-0803 | 0531-0827  11
 12  0720-0456 | 0655-0531 | 0616-0602 | 0626-0734 | 0548-0804 | 0531-0828  12
 
 13  0719-0457 | 0654-0532 | 0614-0603 | 0625-0735 | 0547-0805 | 0531-0828  13
 14  0719-0458 | 0653-0533 | 0612-0604 | 0623-0736 | 0546-0806 | 0531-0828  14
 15  0719-0459 | 0652-0535 | 0611-0605 | 0622-0737 | 0545-0806 | 0531-0829  15
 16  0718-0501 | 0650-0536 | 0609-0606 | 0620-0738 | 0544-0807 | 0531-0829  16
 
 17  0718-0501 | 0649-0537 | 0608-0607 | 0619-0739 | 0543-0808 | 0531-0830  17
 18  0717-0502 | 0648-0538 | 0606-0608 | 0618-0740 | 0542-0809 | 0531-0830  18
 19  0717-0503 | 0647-0539 | 0604-0609 | 0616-0741 | 0542-0810 | 0531-0830  19
 20  0716-0504 | 0645-0540 | 0603-0610 | 0615-0742 | 0541-0811 | 0532-0830  20
 
 21  0716-0505 | 0644-0541 | 0601-0612 | 0613-0743 | 0540-0812 | 0532-0831  21
 22  0715-0506 | 0642-0543 | 0600-0613 | 0612-0744 | 0539-0813 | 0532-0831  22
 23  0714-0507 | 0641-0544 | 0558-0614 | 0611-0745 | 0539-0814 | 0532-0831  23
 24  0714-0509 | 0640-0545 | 0556-0615 | 0609-0746 | 0538-0815 | 0533-0831  24
 
 25  0713-0510 | 0638-0546 | 0555-0616 | 0608-0747 | 0537-0815 | 0533-0831  25
 26  0712-0511 | 0637-0547 | 0553-0617 | 0606-0748 | 0537-0816 | 0533-0831  26
 27  0712-0512 | 0635-0548 | 0552-0618 | 0605-0749 | 0536-0817 | 0534-0832  27
 28  0711-0513 | 0634-0549 | 0550-0619 | 0604-0750 | 0536-0818 | 0534-0832  28
 
 29  0710-0514 |                     | 0548-0620 | 0603-0751 | 0535-0819 | 0534-0832  29
 30  0709-0516 |                     | 0547-0621 | 0601-0752 | 0535-0819 | 0535-0831  30
 31  0708-0517 |                     | 0545-0622 |                      | 0534-0820 |                       31


Snowfall

Sept 2009 to Apr 2010

City

Sept-Oct

Nov

Dec

Jan

Feb

Mar Apr

Seasonal Totals

Aurora (Central)

20.2 9.3 13.8 1.8 12.4 15.9   87.6
Brighton 18.4 8.3 12.4 3.1 7.8 15.1   65.1
Broomfield 27.2 11.8 17.3 2.6 15.0 20.1   94.0

Castle Rock 4 NE

27.5 8.7 12.5 0.8 12.0 18.7   80.2

Colorado Sprgs Airport

1.8 1.5 9.4 1.9 9.7 7.2   31.5
Denver DIA 17.2 9.3 11.1 2.6 5.8 12.8   58.8

Denver Downtown

21.4 9.0 16.1 2.8 14.2 17.9   81.4

Golden

28.3 12.9 21.7 5.7 19.9 32.2   120.7

Fort Collins

25.5 6.6 19.5 3.3 12.4 12.5   79.8

Highlands Ranch

34.4 9.7 15.4 1.6 12.8 25.2   99.1

Lakewood

20.5 9.0 12.4 3.1 15.7 16.3   77.0

Littleton

25.9 12.2 16.0 2.3 15.9 19.5   91.8

Parker

22.5 8.2 12.8 1.0 8.7 19.5   72.7

Sedalia - Hwy 67

30.0 10.0 10.5 1.3 13.7 25.0   90.5

Thornton

22.8 8.3 16.6 1.5 11.2 17.1   77.5

Westminster

21.6 13.0 15.2 2.1 16.5 18.6   87.0

Wheatridge

28.8 10.9 15.6 3.4 19.3 17.3   95.3