The Weather Wire

 

June 2008                                                                                                            Volume 16 Number 06

 

Contents

 

 

 
·   Lightning Season
 

·   Drought Monitor

 

·   May

    Summary

 

·   May Stats

 

·   June Preview

 

·   Sunrise/Sunset

 

·   Rainfall Totals

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May 

Avg High 70.7

Avg Low 41.0

Snow - 3.4"

Season Snow - 46.3"

Precipitation - 1.56"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

June

Avg High 82.1

Avg Low 53.0

Avg Snow -  Trace

Avg Precip - 1.56"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Skyview Weather 

2350 N Rocky View Rd

Castle Rock, CO 80108

 

Phone: (303) 688-9175

Fax: (303) 660-0548

 

E-mail:    

tim@skyview-wx.com

 

We’re on the Web!

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

 

Copyright 2008

Skyview Weather

Severe Weather in Colorado

     The spring months of May and June typically bring most of the severe weather to Colorado's Front Range.  We have already witnessed with many hailstorms so far this year and an unforgettable tornado that tore through the town of Windsor.  Why does most of the severe weather occur in the spring versus the summer?

     There are a couple reasons why the spring is more active with severe weather than during the rest of the summer months.  One reason is that cold air still remains above the surface as we transition out of winter into spring.  The cold air aloft helps create severe weather in a couple ways.  First, the cold air helps de-stabilize the atmosphere as warm air at the surface wants to rise to form thunderstorms.  The ground warms rapidly with the increasing sunshine during the spring months with the longest day of the year being the first day of summer or the summer solstice which occurs in June.  Second, the cold air allows hail to form in the updrafts at lower elevations in the cloud which makes the hail stones larger and more likely to reach the surface.  Many summer storms contain hail as well, but the hail travels through a larger warm layer and often melts before reaching the ground.  A second reason is wind shear or changes in wind speed, or direction, or both with height in the atmosphere.  In the spring the jet stream can still be rather active bringing disturbances to Colorado area before it retreats northward during summer.  The stronger winds aloft associated with the jet stream can be tapped into by strong thunderstorms.  Typically, but not always the strongest winds aloft are from the southwest ahead of an approaching trough of low pressure.  Winds at the surface often vary from the upper level winds by both speed and direction.  This in turn causes the wind shear with height in the atmosphere.  When a strong thunderstorm develops in this these conditions the updraft carrying moisture laden air from the surface upwards can rotate.  Storms with a rotating updraft are called super cell thunderstorms, like the storm in May that resulted in a strong tornado that devastated the Windsor area.  The rotation of the updraft can be concentrated by stretching the column of air like a figure skater spinning faster and faster as she brings her arms into her body. 

     There area many other factors that come into play when it comes to severe weather, but cold air aloft and wind shear are two of the major players when it comes to spring severe weather in the state of Colorado.  As we move into the summer months the jet stream weakens and travels north impacting the state less often and reducing wind shear.  As the overall atmosphere warms in the northern hemisphere during summer the air aloft is just not as cold near the surface allowing hail to fall as large rain drops instead of frozen precipitation.  Hail still quite often occurs here in Colorado during the summer months due to our elevation above sea level, but is typically smaller in size and more isolated.              

 

Drought Update

Little in the way of meaningful drought across Colorado as of early June though some dry areas do persist across Eastern Colorado.

The map below shows forecasted temperature deviances for June2008. As can be seen, it is expected that all of Colorado to have normal temperatures for the month of June 2008.

The map below shows forecasted precipitation deviances for June2008.  Normal precipitation is anticipated across  all of Colorado for June 2008.

Little change in conditions is anticipated over the next 3 months, with most of the state not expected to see drought conditions.  Extreme southeastern Colorado  is anticipated to experience drought conditions persisting with some improvement.

May Summary

May of 2008 marks the 7th month in a row for below average precipitation.  There was a monthly total of 1.56" which is 0.76" below the average of 2.32".  For the year now the official measuring site is an incredible 4.22" below normal.  With April and May being some of the wettest months of the year it is probably safe to say that this year will end up being well below average unless a very wet monsoon season occurs.  Temperatures were near normal for highs and below normal for lows with a monthly mean of 1.4 degrees below normal.  The highest temperatures observed was 89 degrees on the 21st and the lowest was 21 on the 3rd, none of which tied or broke any records.  Snowfall was above average, but with 3.4" for the month the 2007-2008 winter season will end up being 15.4" below normal for the Stapleton site.  There were 11 days with measurable precipitation reported which is right at the average.  One record was broken for the month with a maximum wind gust of 61mph from the south, the old record was 60mph set back in 1991.  

May Stats

TEMPERATURE (IN DEGREES F)

 

 

 

 

 

 

AVERAGE MAX

70.7

NORMAL

70.5

DEPARTURE

0.2

AVERAGE MIN

41.0

NORMAL

43.8

DEPARTURE

-2.8

MONTHLY MEAN

55.8

NORMAL

57.2

DEPARTURE

-1.4

HIGHEST

89 on the 21st

LOWEST

21 on the 3rd

 

 

 

 

 

 

DAYS WITH MAX 90 OR ABOVE

0

NORMAL

0.4

DAYS WITH MAX 32 OR BELOW

0

NORMAL

0

DAYS WITH MIN 32 OR BELOW

6

NORMAL

1.5

DAYS WITH MIN ZERO OR BELOW

0

NORMAL

0

 

 

 

 

 

 

TEMPERATURE RECORDS

 

None

 

 

 

 

 

 

 

HEATING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

303

NORMAL

267

DEPARTURE

36

SEASONAL TOTAL

5992

NORMAL

6068

DEPARTURE

-76

 

 

 

 

 

 

COOLING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

28

NORMAL

23

DEPARTURE

5

YEARLY TOTAL

28

NORMAL

25

DEPARTURE

3

 

 

 

 

 

 

PRECIPITATION (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

1.56

NORMAL

2.32

DEPARTURE

-0.76

YEARLY TOTAL

2.31

NORMAL

6.53

DEPARTURE

-4.22

GREATEST IN 24 HOURS

0.49"

DAYS WITH MEASURABLE PRECIPITATION

11

 

 

 

 

 

SNOWFALL (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

3.4"

NORMAL

1.3"

DEPARTURE

2.1

SEASONAL TOTAL

46.3

NORMAL

61.7"

DEPARTURE

-15.4"

GREATEST IN 24 HOURS

3.1" on 5/1

GREATEST DEPTH

N/A

 

 

 

 

 

 

WIND (IN MILES PER HOUR)

 

 

 

 

 

 

AVERAGE SPEED 10.5mph

PEAK WIND GUST

61mph from the south

 

 

 

 

 

 

MISCELLANEOUS WEATHER

 

 

 

 

 

 

NUMBER OF DAYS WITH THUNDERSTORMS

8

NORMAL

6

NUMBER OF DAYS WITH HEAVY FOG

3

NORMAL

1

NUMBER OF DAYS WITH HAIL

2

 

 

PERCENT OF SUNSHINE

53%

NORMAL

64%

 

 

 

June Preview

June is the transition month from spring to summer and is typically the severe weather month for Denver and surrounding areas.  Nearly half of all tornadoes that are reported in eastern Colorado and along the Front Range during the spring and summer months occur during the month of June.  One storm many of you may remember occurred on June 13, 1984.  This strong thunderstorm brought large hail to the metro area and is one of the worst and costliest hail storms in Denver history.  The temperatures really begin to rise during June with six days with highs of 90 degrees or above on average.  The record high for the month is 104 recorded on the 26th in 1994.  Cold weather can still occur in early June as the record monthly low of 30 degrees was recorded on the 2nd in 1951.  There have only been 5 years with a trace of snow or greater, so it is safe to say that there will not be any more snow to fall this winter season.  Precipitation records range from a trace to 4.96" with an average of 1.56'.  Even if we matched the record rainfall for the month we would still be below average for the year.              

DENVER'S NOVEMBER CLIMATOLOGICALLY NORMAL

(NORMAL PERIOD 1971-2000)

 

 

TEMPERATURE

 

 

 

AVERAGE HIGH

82.1

AVERAGE LOW

53.0

MONTHLY MEAN

67.6

DAYS WITH HIGH 90 OR ABOVE

6

DAYS WITH HIGH 32 OR BELOW

0

DAYS WITH LOW 32 OR BELOW

0

DAYS WITH LOWS ZERO OR BELOW

0

 

 

PRECIPITATION

 

 

 

MONTHLY MEAN

1.56"

DAYS WITH MEASURABLE PRECIPITATION

9

AVERAGE SNOWFALL IN INCHES

Trace

DAYS WITH 1.0 INCH OF SNOW OR MORE

0

 

 

MISCELLANEOUS AVERAGES

 

 

 

HEATING DEGREE DAYS

60

COOLING DEGREE DAYS

136

WIND SPEED (MPH)

8.9mph

WIND DIRECTION

South

DAYS WITH THUNDERSTORMS

10

DAYS WITH DENSE FOG

Less than 1

PERCENT OF SUNSHINE POSSIBLE

70%

 

 

EXTREMES

 

 

 

RECORD HIGH

104 on June 26, 1994

RECORD LOW

30 on June 2, 1951

WARMEST

73.5 degrees in 1994

COLDEST

60.6 degrees in 1967

WETTEST

4.96" in 1882

DRIEST

Trace in 1890

SNOWIEST

0.4" in 1919

LEAST SNOWIEST

0.0"
 

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  0720-0445 | 0708-0517 | 0632-0551 | 0643-0723 | 0600-0753 | 0533-0821  01
02  0721-0446 | 0707-0519 | 0630-0552 | 0641-0724 | 0558-0754 | 0533-0822  02
03  0721-0447 | 0706-0520 | 0629-0553 | 0640-0725 | 0557-0755 | 0533-0823  03
04  0721-0448 | 0705-0521 | 0627-0554 | 0638-0726 | 0556-0756 | 0532-0823  04

05  0721-0449 | 0704-0522 | 0626-0555 | 0637-0727 | 0555-0757 | 0532-0824  05
06  0721-0450 | 0703-0523 | 0624-0556 | 0635-0728 | 0554-0758 | 0532-0825  06
07  0721-0451 | 0702-0525 | 0623-0557 | 0633-0729 | 0553-0759 | 0532-0825  07
08  0721-0452 | 0701-0526 | 0621-0558 | 0632-0730 | 0551-0800 | 0531-0826  08

09  0720-0453 | 0700-0527 | 0720-0700 | 0630-0731 | 0550-0801 | 0531-0826  09
10  0720-0454 | 0658-0528 | 0718-0701 | 0629-0732 | 0549-0802 | 0531-0827  10
11  0720-0455 | 0657-0529 | 0716-0702 | 0627-0733 | 0548-0803 | 0531-0827  11
12  0720-0456 | 0656-0530 | 0715-0703 | 0626-0734 | 0547-0804 | 0531-0828  12

13  0720-0457 | 0655-0532 | 0713-0704 | 0624-0735 | 0546-0805 | 0531-0828  13
14  0719-0458 | 0654-0533 | 0712-0705 | 0623-0736 | 0545-0806 | 0531-0829  14
15  0719-0459 | 0652-0534 | 0710-0706 | 0621-0737 | 0545-0807 | 0531-0829  15
16  0718-0500 | 0651-0535 | 0708-0707 | 0620-0738 | 0544-0808 | 0531-0829  16

17  0718-0500 | 0650-0536 | 0707-0708 | 0618-0739 | 0543-0809 | 0531-0830  17
18  0718-0501 | 0649-0537 | 0705-0709 | 0617-0740 | 0542-0810 | 0531-0830  18
19  0717-0502 | 0647-0539 | 0704-0710 | 0615-0741 | 0541-0811 | 0531-0830  19
20  0717-0503 | 0646-0540 | 0702-0711 | 0614-0742 | 0540-0812 | 0532-0831  20

21  0716-0505 | 0645-0541 | 0700-0712 | 0613-0743 | 0540-0812 | 0532-0831  21
22  0715-0506 | 0643-0542 | 0659-0713 | 0611-0744 | 0539-0813 | 0532-0831  22
23  0715-0507 | 0642-0543 | 0657-0714 | 0610-0745 | 0538-0814 | 0532-0831  23
24  0714-0508 | 0640-0544 | 0656-0715 | 0609-0746 | 0538-0815 | 0533-0831  24

25  0713-0509 | 0639-0545 | 0654-0716 | 0607-0747 | 0537-0816 | 0533-0831  25
26  0713-0510 | 0638-0547 | 0652-0717 | 0606-0748 | 0536-0817 | 0533-0831  26
27  0712-0511 | 0636-0548 | 0651-0718 | 0605-0749 | 0536-0817 | 0534-0832  27
28  0711-0513 | 0635-0549 | 0649-0719 | 0603-0750 | 0535-0818 | 0534-0832  28

29  0710-0514 | 0633-0550 | 0648-0720 | 0602-0751 | 0535-0819 | 0535-0832  29
30  0709-0515 |                      | 0646-0721 | 0601-0752 | 0534-0820 | 0535-0831  30
31  0709-0516

 Rainfall

May 2008 to September 2008

City

May

June

July

August September

Seasonal Totals

Aurora (Central)

2.17         2.17"
Brighton 1.65         1.65"
Broomfield 2.01         2.01"

Castle Rock 4 NE

1.54         1.54"

Colorado Sprgs Airport

0.34         0.34"
Denver Stapleton 1.56         1.56"

Denver Downtown

2.40         2.40"

Golden

1.93         1.93"

Highlands Ranch

2.48         2.48"

Lakewood

1.77         1.77"

Littleton

2.24         2.24"

Parker

1.65         1.65"

Sedalia - Hwy 67

2.36         2.36"

Thornton

1.77         1.77"

Westminster

2.01         2.01"

Wheatridge

1.89         1.89"