The Weather Wire

 

July 2008                                                                                                            Volume 16 Number 07

 

Contents

 

 

 
·   Fire Weather
 

·   Drought Monitor

 

·   June

    Summary

 

·   June Stats

 

·   July Preview

 

·   Sunrise/Sunset

 

·   Rainfall Totals

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June 

Avg High - 83.9

Avg Low - 50.9

Snow - 0.0"

Season Snow - 46.3"

Precipitation - 0.73"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

July

Avg High - 88.0

Avg Low - 58.7

Avg Snow -  0.0"

Avg Precip - 2.16"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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

Fire Weather

The spring and early summer of 2008 has been very dry along Colorado’s Front Range with well below normal precipitation.  The dry weather has resulted in fire concerns for many locations.  Skyview provides fire weather forecasts and current weather information from local weather stations to help local fire fighters and wish to share some terminology we use in our forecasts and additional information with the rest of you.

Lightning Activity Level or (LAL) Definitions

LAL 1

No thunderstorms

LAL 2

Isolated thunderstorms.  Light rain will occasionally reach the ground.  Lightning is very infrequent, 1-5 cloud-to-ground strikes in a 5 minute period.

LAL 3

Widely scattered thunderstorms.  Light to moderate rain will reach the ground.  Lightning is infrequent, 6-10 cloud-to-ground strikes in a 5 minute period.

LAL 4

Scattered thunderstorms.  Moderate rain is commonly produced.  Lightning is frequent, 11-15 cloud-to-ground strikes in a 5 minute period

LAL 5

Numerous thunderstorms.  Rainfall is moderate to heavy.  Lightning is frequent and intense, greater than 15 cloud-to–ground strikes in a 5 minute period.

LAL 6

Same as LAL 3 except thunderstorms are dry (no rain reaches the ground).  This type of lightning has the potential for extreme fire activity and is normally highlighted in fire weather forecasts with a Red Flag Warning.

* = Information from: Intermediate Wildland Fire Behavior: Student Workbook. National Wildfire Coordinating Group, July 1994  

Haines Index* - Haines Index combines the effects of instability and dry air to determine conditions in which an existing fire has the potential to spread rapidly.  It should not be used to determine if a fire will start.  Since wind is not a parameter of the Haines Index, it is best used for plume-dominated fires which can develop extreme surface winds through their own internal heat.  The Haines Index is yet to be tested on wind-driven fires…  When the value is 5 or 6, the probability of extreme fire behavior, including torching, crowning and spotting is significantly increased.  Critical fire behavior is usually low, with minimal fire spread when the values are 4 or less… * = Definition from:  http://www.crh.noaa.gov/fsd/firewx/firedef.php

Haines Index

Haines Index

Potential for Large Fire Growth

2 or 3

Very Low

4

Low

5

Moderate

6

High

Haines Index values of 4 or higher are days with a dry and unstable air mass, while 4 or lower are typically days with cool/moist and a more stable air mass.  A high Haines Index value in tandem with a high LAL value and strong surface winds can combine for disaster.  This is the worst type of scenario and the Front Range of Colorado is primed for these types of conditions. Winds have been breezy through the spring and summer so far, fuels for fire are dry due to below normal precipitation, the atmosphere becomes more unstable with the hot temperatures of summer and thunderstorms that do manage to develop produce more lightning than rainfall.  Unless changes in the current weather pattern change significantly expect more Red Flag Warnings and the threat for wildland fire to increase further.  It’s not all doom and gloom as monsoonal moisture is late to arrive this year, but should return by late July bringing much needed rainfall to the Front Range of Colorado from scattered afternoon thunderstorms.  

Drought Update

Some areas of drought are beginning to appear once again across much of eastern Colorado.

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

The map below shows forecasted precipitation deviances for July 2008.  Normal precipitation is anticipated across eastern Colorado as well as extreme western Colorado, with above normal precipitation anticipated for the mountain areas of Colorado for July 2008.

Little change in conditions is anticipated over the next 3 months, with most of the state not expected to see drought conditions.  Southeastern Colorado is anticipated to experience drought conditions improving over the next 3 months.

June Summary


June 2008 - Drier with near normal temperatures.

June 2008 was a mundane month with no noteworthy weather statistics to mention.  Precipitation started off the month like June 2008 might be a record setter.  In the first 5 days 0.71 inch of rainfall was measured at DIA.  But the rest of June only 0.02 inch additional rainfall occurred. The 24 hour maximum total was 0.70 inch between the 4th and 5th.  No precipitations records were set or tied during June 2008.

Temperatures ranged between a high of 95 degrees on the 26th down to a low of 37 degrees on the 12th.  The average temperature was 67.4 degrees which was only 0.2 degrees below the normal of 67.6 degrees.  Only one record was tied, 47 degrees on the 29th last set in 1995.  There were ten 90 degree days which is 4 above normal.  Ten is also the total for the year.

There was no snowfall recorded.  The most snowfall ever was 0.4 inch in June 1919. There are other reports of snowfall, however, this is actually hail which is sometimes entered into the snowfall column with an asterisk.  For June 2008 small hail was reported at DIA but not at the former Stapleton International Airport, which is where official snowfall is measured.

There were 5 thunderstorms recorded at DIA of which only 2 had measurable precipitation.  The storm on the 20th produced small hail.  Only 4 days recorded light fog but no dense fog was observed.  A peak wind gust of 53mph from the southwest was recorded.

 

June Stats

TEMPERATURE (IN DEGREES F)

 

 

 

 

 

 

AVERAGE MAX

83.9

NORMAL

82.1

DEPARTURE

1.8

AVERAGE MIN

50.9

NORMAL

53.0

DEPARTURE

-2.1

MONTHLY MEAN

67.4

NORMAL

67.6

DEPARTURE

-0.2

HIGHEST

95 on the 26th

LOWEST

37 on the 12th

 

 

 

 

 

 

DAYS WITH MAX 90 OR ABOVE

10

NORMAL

6.3

DAYS WITH MAX 32 OR BELOW

0

NORMAL

0

DAYS WITH MIN 32 OR BELOW

0

NORMAL

0

DAYS WITH MIN ZERO OR BELOW

0

NORMAL

0

 

 

 

 

 

 

TEMPERATURE RECORDS

 

Tied record low of 47 degrees on the 29th

 

 

 

 

 

 

 

HEATING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

64

NORMAL

60

DEPARTURE

4

SEASONAL TOTAL

6056

NORMAL

6128

DEPARTURE

-72

 

 

 

 

 

 

COOLING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

144

NORMAL

136

DEPARTURE

8

YEARLY TOTAL

172

NORMAL

161

DEPARTURE

11

 

 

 

 

 

 

PRECIPITATION (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

0.73

NORMAL

1.56

DEPARTURE

-0.83

YEARLY TOTAL

3.04

NORMAL

7.09

DEPARTURE

-5.05

GREATEST IN 24 HOURS

0.70"

DAYS WITH MEASURABLE PRECIPITATION

4

 

 

 

 

 

SNOWFALL (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

0.0

NORMAL

0.0

DEPARTURE

0.0

SEASONAL TOTAL

46.3

NORMAL

61.7"

DEPARTURE

-15.4"

GREATEST IN 24 HOURS

N/A

GREATEST DEPTH

N/A

 

 

 

 

 

 

WIND (IN MILES PER HOUR)

 

 

 

 

 

 

AVERAGE SPEED 10.6mph

PEAK WIND GUST

53mph from the southwest

 

 

 

 

 

 

MISCELLANEOUS WEATHER

 

 

 

 

 

 

NUMBER OF DAYS WITH THUNDERSTORMS

5

NORMAL

10

NUMBER OF DAYS WITH HEAVY FOG

0

NORMAL

< 1

NUMBER OF DAYS WITH HAIL

1

 

 

PERCENT OF SUNSHINE

69%

NORMAL

70%

 

 

 

July Preview

Denver’s weather is notorious for being changeable.  However this is not the case during July.  Most July mornings are sunny with clouds developing during the late morning and early afternoon.  By mid-afternoon, thunderstorms develop over the foothills and drift across the Denver metro area and then onto the eastern plains.  Some of these storms continue to develop and reach severe status.  Severe thunderstorms containing large hail, strong gusty winds and heavy downpours are not uncommon during July for the Denver metro area.

The worst hailstorm on record in Denver history moved across western sections of the city on July 11th 1990.  This ferocious storm dropped baseball to softball sized hail and caused millions of dollars worth of property damage.  July is the stormiest month of the year with thunderstorms occurring about every third day or usually 11 days per month.  Most of the rainfall during the month is the result of slow moving thunderstorms which can cause precipitation to vary tremendously at different locations across the metro area.  It is not unusual for some areas of the city to receive two or three times as much precipitation as other areas.  Flask flooding is also quite possible during July.

July is also the month that Denver has the most 90 degree consecutive days.  There have been 14 times where consecutive streaks of 10 or more 90 degree days have either been entirely in July or at least started in June and finished in July or started in Jusy and finished in August.  The highest consecutive streak of 90 degree days is 18 and occurred twice.  Once in 1901 from July 6th through July 23rd 1901 and again in 1847 from July 1st to July 18th.  More recently we had 17 consecutive 90 degree days in 2000 from June 29th through July 15th.

.

          

DENVER'S NOVEMBER CLIMATOLOGICALLY NORMAL

(NORMAL PERIOD 1971-2000)

 

 

TEMPERATURE

 

 

 

AVERAGE HIGH

88.0

AVERAGE LOW

58.7

MONTHLY MEAN

73.4

DAYS WITH HIGH 90 OR ABOVE

15

DAYS WITH HIGH 32 OR BELOW

0

DAYS WITH LOW 32 OR BELOW

0

DAYS WITH LOWS ZERO OR BELOW

0

 

 

PRECIPITATION

 

 

 

MONTHLY MEAN

2.16"

DAYS WITH MEASURABLE PRECIPITATION

9

AVERAGE SNOWFALL IN INCHES

0

DAYS WITH 1.0 INCH OF SNOW OR MORE

0

 

 

MISCELLANEOUS AVERAGES

 

 

 

HEATING DEGREE DAYS

1

COOLING DEGREE DAYS

261

WIND SPEED (MPH)

8.3mph

WIND DIRECTION

South

DAYS WITH THUNDERSTORMS

11

DAYS WITH DENSE FOG

Less than 1

PERCENT OF SUNSHINE POSSIBLE

71%

 

 

EXTREMES

 

 

 

RECORD HIGH

105 on July 20, 2005

RECORD LOW

42 on July 4, 1903

WARMEST

77.8 degrees in 1934

COLDEST

67.4 degrees in 1985

WETTEST

6.41" in 1965

DRIEST

0.01" in 1901

SNOWIEST

0.0"

LEAST SNOWIEST

0.0"
 

Sunrise/Sunset (Jul - December Denver area)

             JUL                 AUG            SEP               OCT              NOV               DEC
______________________________________________________________________________
            sr - ss           sr - ss           sr - ss            sr - ss            sr - ss           sr - ss
 01  0536-0831 | 0559-0813 | 0628-0731 | 0656-0643 | 0729-0557 | 0702-0436  01
 02  0536-0831 | 0600-0812 | 0629-0730 | 0657-0641 | 0630-0456 | 0703-0435  02
 03  0537-0831 | 0601-0811 | 0630-0728 | 0658-0639 | 0631-0455 | 0704-0435  03
 04  0537-0831 | 0602-0810 | 0631-0727 | 0659-0638 | 0632-0454 | 0705-0435  04

 05  0538-0831 | 0603-0809 | 0632-0725 | 0700-0636 | 0633-0453 | 0706-0435  05
 06  0538-0830 | 0604-0807 | 0633-0723 | 0701-0635 | 0634-0452 | 0707-0435  06
 07  0539-0830 | 0604-0806 | 0634-0722 | 0702-0633 | 0636-0451 | 0708-0435  07
 08  0540-0830 | 0605-0805 | 0634-0720 | 0703-0632 | 0637-0450 | 0708-0435  08

 09  0540-0829 | 0606-0804 | 0635-0719 | 0704-0630 | 0638-0449 | 0709-0435  09
 10  0541-0829 | 0607-0803 | 0636-0717 | 0705-0628 | 0639-0448 | 0710-0435  10
 11  0542-0829 | 0608-0801 | 0637-0715 | 0706-0627 | 0640-0447 | 0711-0435  11
 12  0542-0828 | 0609-0800 | 0638-0714 | 0707-0625 | 0641-0446 | 0712-0435  12

 13  0543-0828 | 0610-0759 | 0639-0712 | 0708-0624 | 0642-0445 | 0712-0436  13
 14  0544-0827 | 0611-0758 | 0640-0710 | 0709-0622 | 0644-0444 | 0713-0436  14
 15  0544-0827 | 0612-0756 | 0641-0709 | 0710-0621 | 0645-0443 | 0714-0436  15
 16  0545-0826 | 0613-0755 | 0642-0707 | 0711-0619 | 0646-0443 | 0714-0437  16

 17  0546-0826 | 0614-0753 | 0643-0706 | 0712-0618 | 0647-0442 | 0715-0437  17
 18  0547-0825 | 0615-0752 | 0644-0704 | 0713-0617 | 0648-0441 | 0716-0437  18
 19  0548-0824 | 0616-0751 | 0645-0702 | 0715-0615 | 0649-0441 | 0716-0438  19
 20  0548-0824 | 0617-0749 | 0646-0701 | 0716-0614 | 0650-0440 | 0717-0438  20

 21  0549-0823 | 0618-0748 | 0647-0659 | 0717-0612 | 0651-0439 | 0717-0439  21
 22  0550-0822 | 0619-0746 | 0648-0657 | 0718-0611 | 0653-0439 | 0718-0439  22
 23  0551-0821 | 0619-0745 | 0648-0656 | 0719-0610 | 0654-0438 | 0718-0440  23
 24  0552-0820 | 0620-0744 | 0649-0654 | 0720-0608 | 0655-0438 | 0719-0440  24

 25  0553-0820 | 0621-0742 | 0650-0652 | 0721-0607 | 0656-0437 | 0719-0441  25
 26  0554-0819 | 0622-0741 | 0651-0651 | 0722-0606 | 0657-0437 | 0719-0442  26
 27  0554-0818 | 0623-0739 | 0652-0649 | 0723-0604 | 0658-0437 | 0720-0442  27
 28  0555-0817 | 0624-0738 | 0653-0648 | 0724-0603 | 0659-0436 | 0720-0443  28

 29  0556-0816 | 0625-0736 | 0654-0646 | 0725-0602 | 0700-0436 | 0720-0444  29
 30  0557-0815 | 0626-0734 | 0655-0644 | 0727-0559 | 0701-0436 | 0720-0445  30
 31  0558-0814 | 0627-0733 |           | 0728-0558 |           | 0720-0445  31

31  0709-0516

 Rainfall

May 2008 to September 2008

City

May

June

July

August September

Seasonal Totals

Aurora (Central)

2.17 0.83       3.00"
Brighton 1.65 0.67       2.32"
Broomfield 2.01 0.94       2.95"

Castle Rock 4 NE

1.54 0.55       2.09"

Colorado Sprgs Airport

0.34 0.52       0.86"
Denver Stapleton 1.56 0.73       2.29"

Denver Downtown

2.40 0.47       2.87"

Golden

1.93 1.30       3.23"

Highlands Ranch

2.48 0.35       2.83"

Lakewood

1.77 0.98       2.75"

Littleton

2.24 0.59       2.83"

Parker

1.65 0.71       2.36"

Sedalia - Hwy 67

2.36 0.35       2.71"

Thornton

1.77 0.39       2.16"

Westminster

2.01 0.94       2.95"

Wheatridge

1.89 0.67       2.56"