The Weather Wire

 

March 2009                                                                                                            Volume 17 Number 03

 

Contents

 

 

 
·   Front Range Lightning
 

·   Drought Monitor

 

·   February

    Summary

 

·   February Stats

 

·   March Preview

 

·   Sunrise/Sunset

 

·   Snow Totals

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February 

Avg High - 53.0

Avg Low - 21.6

Snow - Trace

Season Snow - 16.9"

Precipitation - 0.04"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

March

Avg High - 53.7

Avg Low - 25.4

Avg Snow -  11.7"

Avg Precip - 1.28"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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 2009

Skyview Weather

Front Range Lightning

With all of the mild weather lately it is a reminder that spring is on the way and so is lightning season.  As temperatures warm with increasing sunlight during the spring months the atmosphere becomes more unstable allowing for convective type precipitation or more intense precipitation and the threat of lightning.  Even when temperatures are cold enough to support snow at the surface lightning can occur and often does a time or two each spring along the Front Range.  This phenomenon is called “thundersnow” and can produce very heavy snowfall rates for a short time in a small geographical area.  Thundersnow is rare, but can be dangerous because people often do not associate lightning with snowfall.  Here in Colorado many people enjoy outdoor activities in the winter such as skiing or snowboarding and can accidently be in a bad spot at a bad time.  Some precursors to thundersnow can be recognized with the type and intensity of precipitation.  One form of precipitation called graupel or “soft hail” and can prelude a lightning strike as this type of precipitation forms in a convective atmosphere like hail in a summertime thunderstorm.  Very heavy snow with literal “snow balls” or “clumps” of snow falling can also indicate a strike may occur as this is truly heavy snow with rates of greater than 3” per hour.

Lightning becomes increasingly more common in April and May with a maximum in August when the monsoon season is in full force.  Looking forward to these months I thought it would be good to look back at 2008 and see how many lightning days we had starting April 1st and ending on October 31st.  Below are graphs for number of thunderstorm days per month for a number of Front Range locations:

The thunderstorm season in 2008 was nothing special with below average precipitation for many areas.  For a day to be considered a thunderstorm day there had to be a thunderstorm over the area that produced at least one strike.  No precipitation has to fall for a storm to be called a thunderstorm, only lightning need be present as there are many days with “dry” thunderstorms.  If we make the range even tighter from April 15th through September 15th, here is the % of days with thunderstorms:

Broomfield is surprisingly low in number of thunderstorm days compared to other Front Range locations and can be contributed to its small geographical area. Obviously the areas with the highest % of thunderstorm days are the foothills and Palmer Divide as these are “hot spots” for lightning and receive more strikes than almost anywhere else in the country except the extreme southeast US, but these areas have a much longer thunderstorm season, nearly year round.  So, during the summer months parts of Colorado receive more lightning than anywhere else in America!  Below is a strike density map for Colorado the brighter colors indicate areas with higher strike density:

Notice the bulls eye over the Palmer Divide and western foothills extending through the Pikes Peak region.  This part of Colorado receives significantly more lightning than anywhere else in the state and this region is becoming more and more populated every year.  A special offer from Skyview Weather this year:  Half off our lightning services for the month of April!     

 

 

Drought Update

Areas of drought are spreading across much of eastern Colorado as well as northwest Colorado as a result of our precipitation deficit year to date. 

The map below shows forecasted temperature deviances for March 2009. As can be seen, it is expected that all of Colorado to have above normal temperatures for the month of March 2009. 

The map below shows forecasted precipitation deviances for March 2009.  Normal precipitation is anticipated for northern and western Colorado, with below normal precipitation expected for southeast Colorado for March 2009.

Areas of drought along the front range of Colorado as well as southeast Colorado are expected to develop as a result of the low levels of precipitation over the last several months.

February Summary

February of 2009 is now the driest February ever!  Since records have been taken all the way back in 1882 there has never been a trace of snowfall reported.  This is due to the change of reporting locations from the old Stapleton site to DIA.  The old site would have reported measurable snow and this would not have been the least snowiest February on record.  Keep this in mind as we are now comparing apples to oranges in the climate department now that we are comparing the climate from one location to a new one.  Lower than average snowfall will likely be measured at DIA for years to come even if the old site has "normal" snow.  This is due to lower elevation and proximity to the foothills.  As far as temperatures go we were incredibly warm not to set any temperature records.  The average high for the month was 53 degrees, an astounding 5.8 degrees above normal, more like March.  The average low was not as far off with a departure of 2.5 degrees on the warm side.  February of 2009 can be remembered as warm, windy and very dry.  The drought watch is now on!

February Stats

TEMPERATURE (IN DEGREES F)

 

 

 

 

 

 

AVERAGE MAX

53.0

NORMAL

47.2

DEPARTURE

5.8

AVERAGE MIN

21.6

NORMAL

19.1

DEPARTURE

2.5

MONTHLY MEAN

37.3

NORMAL

33.2

DEPARTURE

4.1

HIGHEST

68 on the 5th and 24th

LOWEST

1 on the 21st

 

 

 

 

 

 

DAYS WITH MAX 90 OR ABOVE

0

NORMAL

0.0

DAYS WITH MAX 32 OR BELOW

4

NORMAL

6.5

DAYS WITH MIN 32 OR BELOW

26

NORMAL

29.8

DAYS WITH MIN ZERO OR BELOW

1

NORMAL

3.8

 

 

 

 

 

 

TEMPERATURE RECORDS

 

No records tied or broken.

 

 

 

 

 

 

 

HEATING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

764

NORMAL

892

DEPARTURE

-128

SEASONAL TOTAL

4057

NORMAL

4489

DEPARTURE

-432

 

 

 

 

 

 

COOLING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

0

NORMAL

0

DEPARTURE

0

YEARLY TOTAL

0

NORMAL

0

DEPARTURE

0

 

 

 

 

 

 

PRECIPITATION (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

0.04

NORMAL

0.49

DEPARTURE

-0.45

YEARLY TOTAL

0.17

NORMAL

1.00

DEPARTURE

-0.83

GREATEST IN 24 HOURS

0.03" on the 20th

DAYS WITH MEASURABLE PRECIPITATION

2

 

 

 

 

 

SNOWFALL (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

TR

NORMAL

6.3

DEPARTURE

-6.3

SEASONAL TOTAL

16.9

NORMAL

39.6

DEPARTURE

-22.7

GREATEST IN 24 HOURS

TR on 4 days

GREATEST DEPTH

No measurable depth

 

 

 

 

 

 

WIND (IN MILES PER HOUR)

 

 

 

 

 

 

AVERAGE SPEED 10.9

PEAK WIND GUST

52mph from the WSW

 

 

 

 

 

 

MISCELLANEOUS WEATHER

 

 

 

 

 

 

NUMBER OF DAYS WITH THUNDERSTORMS

0

NORMAL

0

NUMBER OF DAYS WITH HEAVY FOG

3

NORMAL

N/A

NUMBER OF DAYS WITH HAIL

0

 

 

PERCENT OF SUNSHINE

77%

NORMAL

70%

 

 

 

March Preview

We all know that March can bring some of the largest snow storms in Denver history and unfortunately we would need that and then some to get to near normal in snowfall this winter.  For the month of March 11.7" of snow falls on average with 1.28" of total precipitation.  Denver (DIA) is currently 22" behind in snowfall and with the nearly 12" we average this month almost 3 feet of snow is needed just to get back to normal.  With the weather pattern we have experienced so far this winter with fast moving storms and unfavorable upper level flow I do not believe that we have much of a chance to even get to around normal in snowfall for the month, let alone make up some ground in the snowfall deficit.  Temperatures really begin to turn around in March as overnight lows average the mid 20s instead of the teens in January and December.  Referring to normal in March may be a little misleading as we are typically much warmer or colder with fast changing weather conditions. 

DENVER'S NOVEMBER CLIMATOLOGICALLY NORMAL

(NORMAL PERIOD 1971-2000)

 

 

TEMPERATURE

 

 

 

AVERAGE HIGH

53.7

AVERAGE LOW

25.4

MONTHLY MEAN

39.6

DAYS WITH HIGH 90 OR ABOVE

0

DAYS WITH HIGH 32 OR BELOW

3

DAYS WITH LOW 32 OR BELOW

24

DAYS WITH LOWS ZERO OR BELOW

1

 

 

PRECIPITATION

 

 

 

MONTHLY MEAN

1.28"

DAYS WITH MEASURABLE PRECIPITATION

9

AVERAGE SNOWFALL IN INCHES

11.7

DAYS WITH 1.0 INCH OF SNOW OR MORE

4

 

 

MISCELLANEOUS AVERAGES

 

 

 

HEATING DEGREE DAYS

788

COOLING DEGREE DAYS

0

WIND SPEED (MPH)

9.7mph

WIND DIRECTION

South

DAYS WITH THUNDERSTORMS

<1

DAYS WITH DENSE FOG

1

PERCENT OF SUNSHINE POSSIBLE

69%

 

 

EXTREMES

 

 

 

RECORD HIGH

84 on 3/26/1971

RECORD LOW

-11 on 3/28/1886

WARMEST

50.4 degrees in 1910

COLDEST

26.4 degrees in 1912

WETTEST

4.56" in 1983

DRIEST

0.11" in 1908

SNOWIEST

35.2" in 2003

LEAST SNOWIEST

0.3" in 1883
 

Sunrise/Sunset (Jul - December 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 | 0632-0551 | 0643-0723 | 0600-0753 | 0534-0821  01
 02  0721-0447 | 0706-0519 | 0631-0552 | 0642-0724 | 0559-0754 | 0533-0822  02
 03  0721-0448 | 0705-0521 | 0629-0553 | 0640-0725 | 0557-0755 | 0533-0822  03
 04  0721-0449 | 0704-0522 | 0628-0554 | 0638-0726 | 0556-0756 | 0532-0823  04

 05  0721-0450 | 0703-0523 | 0626-0555 | 0637-0727 | 0555-0757 | 0532-0824  05
 06  0721-0451 | 0702-0524 | 0625-0556 | 0635-0728 | 0554-0758 | 0532-0824  06
 07  0721-0452 | 0701-0525 | 0623-0557 | 0634-0729 | 0553-0759 | 0532-0825  07
 08  0720-0452 | 0700-0527 | 0721-0658 | 0632-0730 | 0552-0800 | 0531-0826  08

 09  0720-0453 | 0659-0528 | 0720-0659 | 0631-0731 | 0551-0801 | 0531-0826  09
 10  0720-0454 | 0658-0529 | 0718-0700 | 0629-0732 | 0550-0802 | 0531-0827  10
 11  0720-0456 | 0656-0530 | 0717-0701 | 0628-0733 | 0549-0803 | 0531-0827  11
 12  0720-0457 | 0655-0531 | 0715-0702 | 0626-0734 | 0548-0804 | 0531-0828  12

 13  0719-0458 | 0654-0533 | 0714-0704 | 0625-0735 | 0547-0805 | 0531-0828  13
 14  0719-0459 | 0653-0534 | 0712-0705 | 0623-0736 | 0546-0806 | 0531-0829  14
 15  0719-0500 | 0651-0535 | 0710-0706 | 0622-0737 | 0545-0807 | 0531-0829  15
 16  0718-0501 | 0650-0536 | 0709-0707 | 0620-0738 | 0544-0808 | 0531-0829  16

 17  0718-0501 | 0649-0537 | 0707-0708 | 0619-0739 | 0543-0809 | 0531-0830  17
 18  0717-0502 | 0648-0538 | 0706-0709 | 0617-0740 | 0542-0809 | 0531-0830  18
 19  0717-0503 | 0646-0539 | 0704-0710 | 0616-0741 | 0541-0810 | 0531-0830  19
 20  0716-0504 | 0645-0541 | 0702-0711 | 0614-0742 | 0541-0811 | 0532-0831  20

 21  0716-0505 | 0644-0542 | 0701-0712 | 0613-0743 | 0540-0812 | 0532-0831  21
 22  0715-0507 | 0642-0543 | 0659-0713 | 0612-0744 | 0539-0813 | 0532-0831  22
 23  0714-0508 | 0641-0544 | 0658-0714 | 0610-0745 | 0538-0814 | 0532-0831  23
 24  0714-0509 | 0639-0545 | 0656-0715 | 0609-0746 | 0538-0815 | 0533-0831  24

 25  0713-0510 | 0638-0546 | 0654-0716 | 0608-0747 | 0537-0816 | 0533-0831  25
 26  0712-0511 | 0636-0547 | 0653-0717 | 0606-0748 | 0537-0816 | 0533-0831  26
 27  0711-0512 | 0635-0548 | 0651-0718 | 0605-0749 | 0536-0817 | 0534-0832  27
 28  0711-0514 | 0634-0550 | 0650-0719 | 0604-0750 | 0535-0818 | 0534-0832  28

 29  0710-0515 |           | 0648-0720 | 0602-0751 | 0535-0819 | 0534-0832  29
 30  0709-0516 |           | 0646-0721 | 0601-0752 | 0534-0820 | 0535-0831  30
 31  0708-0517 |           | 0645-0722 |           | 0534-0820 |            31

 

 Snowfall

October 2008 to April 2009

City

Oct

Nov

Dec

Jan Feb Mar Apr

Seasonal Totals

Aurora (Central)

 0.0 7.6 12.3 5.8 2.6     28.3
Brighton  0.0 1.6 12.1 5.7 0.8      20.2
Broomfield  0.0 2.3 13.8 7.0 1.0      24.1

Castle Rock 4 NE

 0.3 12.0 9.7 6.6 3.2      31.8

Colorado Sprgs Airport

 TR 2.6 5.2 3.4 0.6      11.8
Denver DIA  TR 1.7 10.3 4.9 TR      16.9

Denver Downtown

 0.0 3.0 8.4 7.8 3.1      22.3

Golden

TR 9.3 19.5 14.9 3.5     47.2

Fort Collins

TR TR 10.5 5.8 4.1      20.4

Highlands Ranch

 0.0 13.9 9.7 8.9 6.0      38.5

Lakewood

 0.0 3.8 8.5 9.5 4.2      26.0

Littleton

 0.0 15.2 10.7 8.7 3.7      38.3

Parker

TR 9.3 14.5 12.4 3.2      39.4

Sedalia - Hwy 67

 TR 14.2 8.0 9.0 3.0      34.2

Thornton

 0.0 3.4 13.6 6.9 1.8      25.7

Westminster

 0.0 2.3 13.4 9.7 1.4      26.8

Wheatridge

 0.0 5.3 12.0 15.6 4.7      37.6