The Weather Wire

 

May 2004                                                                                                                      Volume 11 Number 5

 

Contents

 

·   Lightning

 

·   Drought Monitor

 

·   April

    Summary

 

·   April Stats

 

·   May Preview

 

·   Sunrise/Sunset

 

·   Snowfall Totals

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

April 2004

 

Avg High 59.6

Avg Low 35.4

Snow - 12.0"

Season Snow - 34.7"

Precipitation - 1.76"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

May

Avg High 70.5

Avg Low 43.8

Avg Snow - TR

Avg Precip - 2.32"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Skyview Weather 

2350 N Rocky View Rd

Castle Rock, CO 80104

 

Phone: (303) 688-9175

Fax: (303) 660-0548

 

E-mail:    

tim@skyview-wx.com

 

We’re on the Web!

http://www.anythingweather.com/

 

Copyright 2004

Skyview Weather

Lightning and Golf Just Don’t Mix Well!!!

 

Yes it is that time of year again! Usually March brings the first claps of thunder and the first bolts of lightning. If not in March, definitely in April and May.  On average some 20 million bolts of lightning strike the U.S. during a single year.  Of these over half strike the ground at more than one point.  So we have at a minimum 30 million spots struck by lightning each year!  That is a lot of lightning!  The lightning capital of the nation is Florida, but Colorado is not far behind.  This is due to our closeness to the mountains to our west.  The mountains help to trigger thunderstorms for our area spring through fall. A typical thunderstorm day for Colorado starts out with a sunny morning.  Clouds begin to develop on the mountains and foothills to the west.  As the clouds grow taller and develop into thunderstorms upper level steering winds push the storms out onto the plains.

Lightning is caused as rising air currents in the storms carry water droplets to areas of the clouds below freezing, where some of these droplets freeze.  It is in the mixture of water and ice that a charge develops.  When this charge is sufficiently large a bolt of lightning reaches from the cloud to the ground releasing large amounts of electricity.  In the tropics where the atmosphere is warmer to a higher altitude many storms can and do produce torrential rains but produce no lightning so having a low altitude freezing level such as we have here in Colorado increases the number of lighting strikes we see along the Front Range.  This low freezing level is also conducive to producing hail, which we see quite a bit of in eastern Colorado.

Cloud to ground lightning can kill or injure people by direct or indirect means.  The lightning current can branch off to a person from a tree, fence, pole or other tall object.  In addition, lighting strikes may conduct their current through the ground to a person after the lightning strikes a nearby tree, antenna or other tall object.  The current also may travel through power or telephone lines, or plumbing pipes to a person who is in contact with an electric appliance, telephone or plumbing fixture.  Now lets think about the golfer who is carrying a metal rod and wearing spikes shoes, not the best combination when there is lightning around!

During the past 30 years, lightning killed an average of 73 people per year in the United States based on documented cases. This is more than the average of 68 deaths per year caused by tornadoes and the average of 16 deaths per year caused by hurricanes. However, because lightning usually claims only one or two victims at a time, and because lightning does not cause the mass destruction left in the wake of tornadoes or hurricanes, lightning generally receives much less attention than the more destructive weather-related killers. While documented lightning injuries in the United States average about 300 per year, undocumented injuries caused by lightning are likely much higher.

One of the factors here in Colorado that causes a false sense of security and causes many people to stay out too long is our naturally dry air.  Many times thunderstorms develop, the rain falls from the clouds, but evaporates before it gets to the ground.  Lighting is still produced in these ‘dry’ thunderstorms, but with no rain to chase people indoors the tendency to stay outside until it is too late.  In addition lighting has been know to strike as far as 10 miles from the approaching storm.  So just because it is not raining yet, does not mean you are safe from lightning!! You should always stay alert to changing weather conditions while you are outside and have a good idea where you will go if lighting becomes a threat. 

The most important statement for everyone to understand, memorize and act on is:  NO PLACE OUTSIDE IS SAFE FROM LIGHTING NEAR THUNDERSTORMS!!

 

Drought Update

In many portions of Colorado, April 2004 was saw normal to above precipitation.  As a result, drought conditions improved across much of Colorado.

The map below shows forecasted temperature deviances for the May2004 time period. As can be seen, above normal temperatures are expected for  all of Colorado for May, with the exception of the far western portions of Colorado, where above normal temperatures are forecast.

The map below shows forecasted precipitation deviances for May2004.  Normal or near normal precipitation is expected for May 2004 for the southeast half of the state, while the northwest half of the state is forecast to have below normal precipitation..

As can be seen in the below map, conditions are expected to continue to improve across the southeastern half of the state, while areas in the northwestern half of the state are not forecast to improve through July.

April Summary

April 2004 was again below normal for precipitation despite having 13 days with precipitation.  It is worth noting though that the DIA site tends to be drier than much of the metro area and Front Range.  Many areas along the Front Range finished the month well above normal for precipitation.  Eight of the 13 days had 0.10 inch of precipitation or greater. The monthly precipitation for April finished with a total of 1.76 inches, which was 0.17 inch below normal.  The majority of the monthly precipitation (0.97 inch) fell in a 5 day period from April 7th through the 11th.  This now marks the 10th month in a row that Denver has recorded below normal moisture.

Snowfall on the other had was above normal during the month with 12.0 inches measured at Stapleton.  This was 2.9 inches above the normal of 9.1 inches. 5.5 inches of snowfall occurred in a 24 hour period between April 10th and 11th.  The season as a whole though remains below normal with 34.7 inches which is 25.6 inches below the seasonal normals. Normal seasonal snow is 60.3 inches.

Temperatures during April ranged from a high of 81 degrees down to a low of 23 degrees.  The average temperature during the month was 47.5 which id only 0.1 degree below the normal of 47.6.

April Stats

TEMPERATURE (IN DEGREES F)

 

 

 

 

 

 

AVERAGE MAX

59.6

NORMAL

60.9

DEPARTURE

-1.3

AVERAGE MIN

35.4

NORMAL

34.2

DEPARTURE

1.2

MONTHLY MEAN

47.5

NORMAL

47.6

DEPARTURE

-0.1

HIGHEST

81 on the 17th

LOWEST

23 on the 12th

 

 

 

 

 

 

DAYS WITH MAX 90 OR ABOVE

0

NORMAL

0

DAYS WITH MAX 32 OR BELOW

0

NORMAL

0

DAYS WITH MIN 32 OR BELOW

11

NORMAL

11

DAYS WITH MIN ZERO OR BELOW

0

NORMAL

0

 

 

 

 

 

 

TEMPERATURE RECORDS

 

1st- New record high 78, old record 77 set in 1933

 

30th-New record low max 33, old 36 in 1954 

 

 

 

 

 

 

 

HEATING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

519

NORMAL

524

DEPARTURE

-5

SEASONAL TOTAL

5457

NORMAL

5801

DEPARTURE

-344

 

 

 

 

 

 

COOLING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

0

NORMAL

2

DEPARTURE

-2

YEARLY TOTAL

0

NORMAL

2

DEPARTURE

-2

 

 

 

 

 

 

PRECIPITATION (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

1.76

NORMAL

1.93

DEPARTURE

-0.17

YEARLY TOTAL

2.34

NORMAL

4.21

DEPARTURE

-1.87

GREATEST IN 24 HOURS

0.43 on the 8th-9th

DAYS WITH MEASURABLE PRECIPITATION

13

NORMAL

  9

 

 

SNOWFALL (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

12

NORMAL

9.1

DEPARTURE

2.9

SEASONAL TOTAL

34.7

NORMAL

60.3

DEPARTURE

-25.6

GREATEST IN 24 HOURS

5.5 on the 10th-11th

GREATEST DEPTH

3 on the 10th

 

 

 

 

 

 

WIND (IN MILES PER HOUR)

 

 

 

 

 

 

AVERAGE SPEED

10.8

NORMAL

10.0

DEPARTURE

0.8

PEAK WIND GUST

53MPH  from the northwest on the 28th

 

 

 

 

 

 

SEA LEVEL PRESSURE (IN INCHES OF MERCURY

 

 

 

 

 

 

HIGHEST

30.38 Inches on the 3rd

LOWEST

29.32 Inches on the 28th

 

 

 

 

 

 

MISCELLANEOUS WEATHER

 

 

 

 

 

 

NUMBER OF DAYS WITH THUNDERSTORMS

2

NORMAL

2

NUMBER OF DAYS WITH HEAVY FOG

4

NORMAL

1

NUMBER OF DAYS WITH HAIL

0

 

 

PERCENT OF SUNSHINE

60

NORMAL

67

TOTAL MINUTES OF SUNSHINE

 

14368

TOTAL MINUTES OF SUNSHINE POSSIBLE

 

23894

 

 

 

May Preview

The weather in Denver is quite changeable throughout the year, however the month of May seems to feature the most changes from year to year, day to day or even hour to hour.  Denver's May weather can include almost any type of weather, even weather that is normally experienced primarily during other months.

Late season frosts can nip plant growth because the average date of the last freeze is May 5th, but the latest date of a Denver freeze in June 2nd.  On the other hand, afternoon temperatures in the 80s are common and the mercury occasionally climbs into the 90s.

May normally marks the beginning of the severe weather season.  Violent thunderstorms with large hail and tornadoes are possible.  These severe storms occur when moisture from the Gulf of Mexico moves into Colorado and collides with cold fronts still moving in from either Canada or from the Pacific Northwest. 

May is also the wettest month of the year and on the average, precipitation normally occurs once every three days.  May is tied with November as having the lowest percentage of possible sunshine.

Snowfall in Denver during May has been nearly non-existent during the past 12 years.  Only a 0.1 inch was recorded during May 1997 and 1990 and only a trace was recorded in 1991.  Denver's high elevation intensifies late season cold air masses and on the average snow occurs in about two out of every five years.

The National Weather Service 30-day outlook model indicates that Denver will have slightly below normal precipitation during May 2004 with temperatures expected to be near normal.

DENVER'S MAY CLIMATOLOGICALLY NORMAL

(NORMAL PERIOD 1971-2000)

 

 

TEMPERATURE

 

 

 

AVERAGE HIGH

70.5

AVERAGE LOW

43.8

MONTHLY MEAN

57.2

DAYS WITH HIGH 90 OR ABOVE

0

DAYS WITH HIGH 32 OR BELOW

0

DAYS WITH LOW 32 OR BELOW

2

DAYS WITH LOWS ZERO OR BELOW

0

 

 

PRECIPITATION

 

 

 

MONTHLY MEAN

2.32 inches

DAYS WITH MEASURABLE PRECIPITATION

11

AVERAGE SNOWFALL IN INCHES

Trace

DAYS WITH 1.0 INCH OF SNOW OR MORE

0

 

 

MISCELLANEOUS MAY AVERAGES

 

 

 

HEATING DEGREE DAYS

267

COOLING DEGREE DAYS

23

WIND SPEED (MPH)

9.3 mph

WIND DIRECTION

SOUTH

DAYS WITH THUNDERSTORMS

6

DAYS WITH DENSE FOG

1

PERCENT OF SUNSHINE POSSIBLE

64

 

 

MAY EXTREMES

 

 

 

RECORD HIGH

95 DEGREES 05/26/1942

RECORD LOW

19 DEGREES 05/03/1907

WARMEST

64.6 DEGREES IN 1934

COLDEST

48.7 DEGREES IN 1920

WETTEST

8.57 INCHES IN 1876

DRIEST

0.06 in 1974

SNOWIEST

15.5 INCHES in 1898

LEAST SNOWIEST

0.0 in many years

Sunrise/Sunset (Denver area)

     Date

Sunrise

Sunset

     May 1  

06:00

19:53

     May 5

05:55

19:57

     May 10

05:59

20:02

     May 15

05:45

20:07

     May 20

05:40

20:11

     May 25

05:37

20:16

     May 30

05:34

20:20

 Snowfall

City

Apr 4 to    Apr 10

Apr 11 to   Apr 12

Apr 22 to    Apr 23

Apr 29 to       Apr 30

Seasonal Totals

Arvada

4.0

0.5

3.0

3.0

43.5

Aurora (Central)

3.0

1.0

4.0

3.0

33.8

Castle Rock  4NE

4.0

1.5

9.0

3.5

56.3

Colorado Springs Airport

2.2

0.7

2.6

0.4

22.4

Douglas Cnty  SE

3.0

1.8

12.0

NA

51.3

Downtown Denver

5.5

1.1

3.7

3.7

39.8

Golden

8.0

0.6

6.0

1.4

68.4

Highlands Ranch

4.0

3.0

7.0

6.0

55.7

Lakewood Cntrl

4.5

2.5

5.0

3.5

53.2

Littleton

6.0

2.5

5.0

0.8

52.8

Louisville

9.0

1.8

5.8

4.3

58.7

Parker

4.0

3.0

5.5

2.0

45.0

Roxborough Park

5.2

4.0

12.0

2.0

70.8

Sedalia

5.5

5.3

15.0

2.0

80.8

Thornton

5.0

1.0

1.0

1.0

34.2

Westminster

5.0

2.0

3.0

6.1

46.4

Wheatridge

5.3

1.6

5.7

4.5

56.2