The Weather Wire

 

November 2007                                                                                                            Volume 15 Number 11

 

Contents

 

 

 
·   Jet Stream
 

·   Drought Monitor

 

·   October

    Summary

 

·   October Stats

 

·   November Preview

 

·   Sunrise/Sunset

 

·   Snow Totals

 

 

 

.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

October 2007

Avg High 68.2

Avg Low 38.8

Snow - 3.0"

Season Snow - 3.0"

Precipitation - 3.03"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

November

Avg High 51.5

Avg Low 23.5

Avg Snow -  10.7"

Avg Precip - 0.98"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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 2007

Skyview Weather

What is the Jet Stream? 

Now that we have moved out of summer into fall the jet stream plays a major role in our everyday weather.  One can imagine the jet stream as a river of air flowing high in the atmosphere steering our winter weather systems through the mid latitudes.  The jet stream is caused by the uneven heating of the earth.  Cold air is denser than warm air and along edges of the cold to warm air the atmosphere has a slope to it.  Try to imagine it as a bowl of cold air and a mound of warm air.  The sides of the bowl represent the temperature difference between the air masses.  The larger the temperature difference the steeper the sides of the bowl.  Now this may be difficult to imagine, but the temperature difference with respect to distance is the driving force of wind.  Where there is the largest change in temperature in distance there is a steeper side to the "bowl" and the strongest winds reside where the slope of the "bowl" is greatest. 

The jet stream winds separate the large scale warm air form the cold air.  Some areas have larger temperature difference than others and the winds are stronger in these areas.  These areas of strongest winds are called jet streaks.  These jet streaks are responsible for movement and location of the comma clouds or storm systems we see on Satellite imagery.  The jet stream is a large feature and so are the storm systems associated with it, some storms can be thousands of miles across and affect more than half of the U.S.

 

In the summer months the jet stream weakens as the North Pole warms and the temperatures difference from north to south decreases.  Jet stream winds decrease and is pushed north into Canada rarely dropping into Colorado.  Daytime heating is the driving force in summer as warm moist air becomes unstable in the afternoon resulting in afternoon and evening thunderstorms.  As the sun sets daytime heat is lost and thunderstorms usually subside overnight only to redevelop the next day. 

This winter the jet stream has remained north of Colorado making for a rather tranquil start to the fall season.  If the jet stream drops further south our weather pattern will become more active here in Colorado during the months of November and December.  November is usually one of the snowiest months in the mountains along and west of the Continental Divide due to the jet stream migrating south steering winter storms into our area.

Drought Update

Most of Colorado continued to see dry conditions, with little improvement in drought conditions along all borders of the state. 

The map below shows forecasted temperature deviances for November 2007. As can be seen, extreme Western Colorado should see above normal temperatures with normal temperatures anticipated elsewhere.

The map below shows forecasted precipitation deviances for November 2007.  Below normal precipitation is expected for most of Colorado for November 2007.

As can be seen in the below map, little overall change is anticipated for much of Colorado through January.  Areas to our north such as Idaho, Montana and western Wyoming will see improving drought conditions as they have been experiencing drought now for up to 10 years in some locations.

October Summary

      October of 2007 was a warmer than average month with an average high of 69.2 degrees which was 2.2 degrees above normal.  Low temperatures were 2.9 degrees warmer than average.  There was a 24-hour precipitation record broken as 2.65" of rainfall fell between the 13th and 14th at DIA.  This was due to an isolated thunderstorm that tracked through the area.  This was the only thunderstorm for the month and small hail was reported as well.  Lesser amounts of rainfall fell throughout the city generally in the 0.5 to 1.5" range.  There was only one snowfall event for the month where 3.0" of snow was officially reported, but southern areas of the city received much higher amounts with 6-9" common along the C-470 area extending into parts of Aurora.  There was an unusually high amount of sunshine for the month as 86% possible sunshine was observed compared to the 72% which is average.  Despite all the sun and above normal temperatures there was only one day that tied a record high.  80 degrees was observed on the 25th which tied an old record set back in 1959.  For the year at DIA we are exactly 1.0" below average precipitation and 3.2" below average snowfall.  The storm track needs to become much more active over the next two months to achieve normal numbers for the year.

October Stats

TEMPERATURE (IN DEGREES F)

 

 

 

 

 

 

AVERAGE MAX

68.2

NORMAL

66.0

DEPARTURE

2.2

AVERAGE MIN

38.8

NORMAL

35.9

DEPARTURE

2.9

MONTHLY MEAN

53.5

NORMAL

51.0

DEPARTURE

2.5

HIGHEST

86 on the 6th

LOWEST

27 on the 22nd

 

 

 

 

 

 

DAYS WITH MAX 90 OR ABOVE

0

NORMAL

0

DAYS WITH MAX 32 OR BELOW

0

NORMAL

0.3

DAYS WITH MIN 32 OR BELOW

5

NORMAL

8.6

DAYS WITH MIN ZERO OR BELOW

0

NORMAL

0

 

 

 

 

 

 

TEMPERATURE RECORDS

 

80 degrees on the 25th tied the old record set in 1959

 

 

 

 

 

 

 

HEATING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

354

NORMAL

436

DEPARTURE

-82

SEASONAL TOTAL

430

NORMAL

582

DEPARTURE

-152

 

 

 

 

 

 

COOLING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

2

NORMAL

0

DEPARTURE

2

YEARLY TOTAL

963

NORMAL

696

DEPARTURE

267

 

 

 

 

 

 

PRECIPITATION (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

3.03"

NORMAL

0.99"

DEPARTURE

2.04"

YEARLY TOTAL

13.20"

NORMAL

14.20"

DEPARTURE

-1.00"

GREATEST IN 24 HOURS

2.65" 10/13 to 10-14

DAYS WITH MEASURABLE PRECIPITATION

7

 

 

 

 

 

SNOWFALL (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

3.0"

NORMAL

4.1"

DEPARTURE

-1.1"

SEASONAL TOTAL

3.0"

NORMAL

6.2"

DEPARTURE

-3.2"

GREATEST IN 24 HOURS

3.0"

GREATEST DEPTH

3.0"

 

 

 

 

 

 

WIND (IN MILES PER HOUR)

 

 

 

 

 

 

AVERAGE SPEED 9.7 mph from the SW

PEAK WIND GUST

56mph from NW

 

 

 

 

 

 

MISCELLANEOUS WEATHER

 

 

 

 

 

 

NUMBER OF DAYS WITH THUNDERSTORMS

1

NORMAL

1

NUMBER OF DAYS WITH HEAVY FOG

0

NORMAL

1

NUMBER OF DAYS WITH HAIL

1

 

 

PERCENT OF SUNSHINE

86%

NORMAL

72%

 

 

 

November Preview

     November can be a roller coaster type of month with warm spring like days as well as powerful winter snowstorms just days apart.  November is the 2nd snowiest month for Front range locations just behind March.  In the mountains this is the time of year where snow begins to pile up creating the "base" and all the ski resorts open for the season.  Overnight lows really begin to drop during this time of year with average lows well into the 20s.  There can be periods very cold temperatures as the first arctic air can intrude from the north.  The record low for November is a bone chilling -18 degrees.  On the flip side the record high is 80 degrees which was set just last year.  Between the two there is a total temperature spread of 98 degrees!  There is less sunshine on average observed during the month of November with only 64% possible sunshine, this is less than any other month during the year.  With a warm start to this November we will likely be above normal in temperature and below normal in snowfall and overall precipitation.  The storm track will most likely become more active the last couple weeks of the month with bringing some much needed moisture to the state.  

DENVER'S NOVEMBER CLIMATOLOGICALLY NORMAL

(NORMAL PERIOD 1971-2000)

 

 

TEMPERATURE

 

 

 

AVERAGE HIGH

51.5

AVERAGE LOW

23.5

MONTHLY MEAN

37.5

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

0

 

 

PRECIPITATION

 

 

 

MONTHLY MEAN

0.98"

DAYS WITH MEASURABLE PRECIPITATION

6

AVERAGE SNOWFALL IN INCHES

10.7"

DAYS WITH 1.0 INCH OF SNOW OR MORE

3

 

 

MISCELLANEOUS AVERAGES

 

 

 

HEATING DEGREE DAYS

826

COOLING DEGREE DAYS

0

WIND SPEED (MPH)

8.2

WIND DIRECTION

SOUTH

DAYS WITH THUNDERSTORMS

0

DAYS WITH DENSE FOG

1

PERCENT OF SUNSHINE POSSIBLE

64

 

 

EXTREMES

 

 

 

RECORD HIGH

80 Degrees on 11/8/2006

RECORD LOW

-18 Degrees on 11/29/1877

WARMEST

50.9 in 1949

COLDEST

22.0 in 1880

WETTEST

3.21" in 1946

DRIEST

TR IN 1899, 1901, 1949

SNOWIEST

42.6" in 1946

LEAST SNOWIEST

0.0 in 1949
 

Sunrise/Sunset (Denver area)

     Date

Sunrise

Sunset

     Nov 1  

07:27

17:59

     Nov 5

06:32

16:54

     Nov 10

06:38

16:49

     Nov 15

06:43

16:45

     Nov 20

06:49

16:41

     Nov 25

06:54

16:38

     Nov 30

07:00

16:36

 Snowfall

October 2007 to March 2008

City

Oct

Nov

Dec

Jan Feb Mar

Seasonal Totals

Aurora (Central)

4.5"           4.5"
Brighton 2.2"           2.2"
Broomfield 2.5"           2.5"

Castle Rock 4 NE

7.0"           7.0"

Colorado Sprgs Airport

0.0"           0.0"
Denver DIA 3.0"           3.0"

Denver Downtown

2.2"           2.2"

Golden

1.8"           1.8"

Highlands Ranch

6.0"           6.0"

Lakewood

3.0"           3.0"

Littleton

3.3"           3.3"

Parker

4.5"           4.5"

Sedalia - Hwy 67

4.0"           4.0"

Thornton

2.5"           2.5"

Westminster

1.8"           1.8"

Wheatridge

2.9"           2.9"