The Weather Wire

 

December 2009                                                                                                            Volume 17 Number 12

 

Contents

 

 

 
   Wind Chill Overview
 

   Drought Monitor

 

   November

    Summary

 

   November Stats

 

   December Preview

 

   Sunrise/Sunset

 

   Snow Totals

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November

Avg High - 56.4

Avg Low - 28.8

Snow - 9.3"

Season Snow - 26.5"

Precipitation - 0.49"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

December

Avg High - 44.1

Avg Low - 16.4

Avg Snow -  8.7"

Avg Precip - 0.63"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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

 

Were on the Web!

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

 

Copyright 2009

Skyview Weather

Wind Chill Overview 

Now that we are entering the coldest part of the winter season we will be dealing with wind chill more often.  Just last week there were Wind Chill Advisories posted for much of the Front Range and many questions were asked about what the effects are and how the cold affects humans and machinery alike.  Below are typical questions asked about wind chill and answers provided by NWS/NOAA.

1. What is wind chill temperature?

A.
The wind chill temperature is how cold people and animals feel when outside. Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold. As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature. Therefore, the wind makes it FEEL much colder. If the temperature is 0 degrees Fahrenheit and the wind is blowing at 15 mph, the wind chill is -19 degrees Fahrenheit. At this wind chill temperature, exposed skin can freeze in 30 minutes.

2. Can wind chill impact my car's radiator or exposed water pipe?


A. The only effect wind chill has on inanimate objects, such as car radiators and water pipes, is to shorten the amount of time for the object to cool. The inanimate object will not cool below the actual air temperature. For example, if the temperature outside is -5 degrees Fahrenheit and the wind chill temperature is -31 degrees Fahrenheit, then your car's radiator will not drop lower than -5 degrees Fahrenheit.

3. What is FROSTBITE?


A. You have frostbite when your body tissue freezes. The most susceptible parts of the body are fingers, toes, ear lobes, or the tip of the nose. Symptoms include a loss of feeling in the extremity and a white or pale appearance. Get Medical attention immediately for frostbite. The area should be SLOWLY re-warmed.

4. What is HYPOTHERMIA?

A.
Hypothermia occurs when body temperature falls below 95 degrees Fahrenheit. Determine this by taking your temperature. Warning signs include uncontrollable shivering, memory loss, disorientation, incoherence, slurred speech, drowsiness, and exhaustion. Get medical attention immediately. If you can't get help quickly, begin warming the body SLOWLY. Warm the body core first, NOT the extremities. Warming extremities first drives the cold blood to the heart and can cause the body temperature to drop further--which may lead to heart failure. Get the person into dry clothing and wrap in a warm blanket covering the head and neck. Do not give the person alcohol, drugs, coffee, or any HOT beverage or food. WARM broth and food is better. About 20% of cold related deaths occur in the home. Young children under the age of two and the elderly, those more than 60 years of age, are most susceptible to hypothermia. Hypothermia can set in over a period of time. Keep the thermostat above 69 degrees Fahrenheit, wear warm clothing, eat food for warmth, and drink plenty of water (or fluids other than alcohol) to keep hydrated. NOTE: Alcohol will lower your body temperature.

5. Tips on How to Dress during cold weather

A.
The best way to avoid hypothermia and frostbite is to stay warm and dry indoors. When you must go outside, dress appropriately. Wear several layers of loose-fitting, lightweight, warm clothing. Trapped air between the layers will insulate you. Remove layers to avoid sweating and subsequent chill. Outer garments should be tightly woven, water repellent, and hooded. Wear a hat, because half of your body heat can be lost from your head. Cover your mouth to protect your lungs from extreme cold. Mittens, snug at the wrist, are better than gloves. Try to stay dry and out of the wind.

6. Avoid Overexertion

A. Your heart is already working overtime in cold weather. The strain from the cold and the hard labor of shoveling heavy snow, walking through drifts or pushing a car may cause a heart attack. Sweating from overexertion could lead to a chill and hypothermia.

7. Is there a Celsius version of the chart?

A. We will look into adding a Celsius version to the web page calculator. In the mean time, you can go to http://www.wrh.noaa.gov/slc/projects/wxcalc/windChill.php

8. Wind chill factor vs. wind chill temperature.

A. These terms are almost the same. The wind chill factor describes what happens to a body when it is cold and windy outside. As wind increases, heat is carried away from the body at a faster rate, driving down both skin temperature (which can cause frostbite) and eventually the internal body temperature (which can kill).

Wind chill temperature is a unit of measurement to describe the wind chill factor. Wind chill temperature is a measure of the combined cooling effect of wind and temperature. Since you and your husband ride motorcycles, you can insert your driving speed to estimate the wind speed and the outside temperature. These two parameters combined will give you the wind chill temperature, or how it feels to you skin. On the bottom of the wind chill chart is the updated wind chill temperature formula.

9. Is it possible to get frostbite if the temperature is above freezing but the wind chill is below freezing?

The air temperature has to be BELOW freezing in order for frostbite to develop on exposed skin. Wind chill can bring the temperature to below freezing for humans and animals.

10. How is the Wind chill is calculated?

The wind chill temperature is calculated using the following formula:

Wind chill (F) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)

Where: T = Air Temperature (F)
V = Wind Speed (mph)
^ = raised to a power (exponential)

Wind chill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph. Bright sunshine may increase the wind chill temperature by 10 to 18 degrees F.

11. When does the National Weather Service issue a Wind chill Advisory or Warning?

Criteria for issuing Wind chill Warnings and Advisories are set locally. For the Rochester, NY area, Wind chill Warnings are issued when the Wind chill Temperature is expected to fall at or below -25 F. Wind chill Advisories are issued when the wind chill temperature is expected to fall between -15F and -24F.

12. Does wind chill only apply to people and animals?

Yes. The only effect wind chill has on inanimate objects, such as car radiators and water pipes, is to more quickly cool the object to cool to the current air temperature. Object will NOT cool below the actual air temperature. For example, if the temperature outside is -5 degrees Fahrenheit and the wind chill temperature is -31 degrees Fahrenheit, then your car's radiator will not drop lower than -5 degrees F.

13. Does humidity or being near a large water body affect on wind chill?

When we tested the new Wind chill Temperature Index (WCTI), our researchers applied the new index to 12 test subjects. The results of the tests showed that relative humidity was an insignificant weather parameter, less than one degree at worst. To simplify the calculation, relative humidity was left out of the formula.

We did research a wet wind chill or blowing water spray. This research was to simulate a person near a body of water or a mariner. These findings are being finalized and may be incorporated for the winter season 2003-2004.

14. How does this chart apply to children?

The tests that were done on Wind chill were conducted on adult subjects. For legal and safety reasons, NWS could not ask for child volunteers. Use the existing chart as a starting point and be even more cautious with children, seniors and persons with compromised health.

Information on cold-related health problems and winter storm safety from the Centers for Disease Control and Prevention (CDC)

 

Q + A was taken from:  http://www.nws.noaa.gov/os/windchill/windchillglossary.shtml

 

 

Drought Update

With the widespread precipitation of the last several months over much of Colorado, though some dry areas have developed in southwestern Colorado.

The map below shows forecasted temperature deviances for December 2009. As can be seen, the eastern 1/3 of Colorado is expected to have below normal temperatures with the remainder of the state seeing normal temperatures.

The map below shows forecasted precipitation deviances for December 2009.  All of Colorado is expected to have normal precipitation for December 2009.

Little in the way of drought remains in Colorado, with the exception of a small area in far southwest Colorado.

November Summary

November of 2009 was relatively tame weather wise with above normal temperatures and below normal snowfall and precipitation.  The average highs was 56.4 and the average low was only 28.8 resulting in a monthly mean temperature of 42.6 degrees which is 5.1 above the normal of 37.5.  Being Denver's 2nd snowiest month, November of 2009 came in a little low in snowfall with 9.3" measured at DIA compared to 10.7" on average.  Still for the year though we are 8.3" above normal thanks to a snowy October.  Sadly % of possible sunshine is no longer recorded, but I would have to think that there was above normal sunshine with the above normal temperatures.

November Stats

TEMPERATURE (IN DEGREES F)

 

 

 

 

 

 

AVERAGE MAX

56.4

NORMAL

51.5

DEPARTURE

4.9

AVERAGE MIN

28.8

NORMAL

23.5

DEPARTURE

5.3

MONTHLY MEAN

42.6

NORMAL

37.5

DEPARTURE

5.1

HIGHEST

77 on the 5th

LOWEST

16 on the 16th

 

 

 

 

 

 

DAYS WITH MAX 90 OR ABOVE

0

NORMAL

0

DAYS WITH MAX 32 OR BELOW

1

NORMAL

2.5

DAYS WITH MIN 32 OR BELOW

22

NORMAL

24.4

DAYS WITH MIN ZERO OR BELOW

0

NORMAL

0.3

 

 

 

 

 

 

TEMPERATURE RECORDS

 

New Record High of 77 on the 5th

 

 

 

 

 

 

 

HEATING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

664

NORMAL

826

DEPARTURE

-162

SEASONAL TOTAL

1479

NORMAL

1408

DEPARTURE

71

 

 

 

 

 

 

COOLING DEGREE DAYS

 

 

 

 

 

 

MONTHLY TOTAL

0

NORMAL

0

DEPARTURE

0

YEARLY TOTAL

533

NORMAL

696

DEPARTURE

-163

 

 

 

 

 

 

PRECIPITATION (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

0.49

NORMAL

0.98

DEPARTURE

-0.49

YEARLY TOTAL

17.67

NORMAL

14.16

DEPARTURE

3.51

GREATEST IN 24 HOURS

0.33" from 11/14 to 11/15

DAYS WITH MEASURABLE PRECIPITATION

3

 

 

 

 

 

SNOWFALL (IN INCHES)

 

 

 

 

 

 

MONTHLY TOTAL

9.3

NORMAL

10.7

DEPARTURE

-1.4

SEASONAL TOTAL

26.5

NORMAL

18.2

DEPARTURE

8.3

GREATEST IN 24 HOURS

7.3" from 11/14 to 11/15

GREATEST DEPTH

NA

 

 

 

 

 

 

WIND (IN MILES PER HOUR)

 

 

 

 

 

 

AVERAGE SPEED

8.8mph from the SSW

PEAK WIND GUST

37mph from the NNW on the 23rd

 

 

 

 

 

 

MISCELLANEOUS WEATHER

 

 

 

 

 

 

NUMBER OF DAYS WITH THUNDERSTORMS

1

NORMAL

<1

NUMBER OF DAYS WITH HEAVY FOG

3

NORMAL

1

NUMBER OF DAYS WITH HAIL

0

 

 

PERCENT OF SUNSHINE

NA

NORMAL

64%

December Preview

Well, since we are already through the first week and a half of the month it would be easy to think that with all the cold weather so far this will be a very cold and snowy month.  But as we know by living in Colorado you don't have to wait long for the weather to change and I would expect a warmer and drier weather regime through at least Christmas.  There may be another unsettled and cold outbreak towards the end of the month, but current weather trends indicate that most of the snow will remain on the western half of the state leaving the Front Range relatively dry for a couple weeks.  The official start of Winter will be on the 21st at 10:47am.  Amazing to think we have not even started winter yet and many areas from the Palmer Divide northward already have over 50-60% of an entire winters worth of snow!  We have already logged above normal precipitation for the year with 17.67" at the start of the month which is 3.51" above normal.

 

DENVER'S NOVEMBER CLIMATOLOGICALLY NORMAL

(NORMAL PERIOD 1971-2000)

 

 

TEMPERATURE

 

 

 

AVERAGE HIGH

44.1

AVERAGE LOW

16.4

MONTHLY MEAN

30.3

DAYS WITH HIGH 90 OR ABOVE

0

DAYS WITH HIGH 32 OR BELOW

5

DAYS WITH LOW 32 OR BELOW

29

DAYS WITH LOWS ZERO OR BELOW

3

 

 

PRECIPITATION

 

 

 

MONTHLY MEAN

0.63"

DAYS WITH MEASURABLE PRECIPITATION

5

AVERAGE SNOWFALL IN INCHES

8.7"

DAYS WITH 1.0 INCH OF SNOW OR MORE

3

 

 

MISCELLANEOUS AVERAGES

 

 

 

HEATING DEGREE DAYS

1078

COOLING DEGREE DAYS

0

WIND SPEED (MPH)

8.4mph

WIND DIRECTION

South

DAYS WITH THUNDERSTORMS

0

DAYS WITH DENSE FOG

1

PERCENT OF SUNSHINE POSSIBLE

67%

 

 

EXTREMES

 

 

 

RECORD HIGH

79 on 12/5/1939

RECORD LOW

-25 on 12/22/1990, 12/24/1876

WARMEST

43.8 in 1933

COLDEST

17.5 in 1983

WETTEST

5.21" in 1913

DRIEST

0.00" in 1881

SNOWIEST

57.4" in 1913

LEAST SNOWIEST

0.0" in 1881
 

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  0535-0831 | 0559-0813 | 0628-0732 | 0656-0643 | 0629-0457 | 0702-0436  01
 02  0536-0831 | 0600-0812 | 0629-0730 | 0657-0641 | 0630-0456 | 0703-0435  02
 03  0536-0831 | 0601-0811 | 0630-0729 | 0658-0640 | 0631-0455 | 0704-0435  03
 04  0537-0831 | 0601-0810 | 0630-0727 | 0659-0638 | 0632-0454 | 0705-0435  04

 05  0538-0831 | 0602-0809 | 0631-0725 | 0700-0637 | 0633-0453 | 0706-0435  05
 06  0538-0830 | 0603-0808 | 0632-0724 | 0701-0635 | 0634-0452 | 0706-0435  06
 07  0539-0830 | 0604-0807 | 0633-0722 | 0702-0634 | 0635-0451 | 0707-0435  07
 08  0539-0830 | 0605-0805 | 0634-0721 | 0703-0632 | 0637-0450 | 0708-0435  08

 09  0540-0830 | 0606-0804 | 0635-0719 | 0704-0630 | 0638-0449 | 0709-0435  09
 10  0541-0829 | 0607-0803 | 0636-0717 | 0705-0629 | 0639-0448 | 0710-0435  10
 11  0541-0829 | 0608-0802 | 0637-0716 | 0706-0627 | 0640-0447 | 0711-0435  11
 12  0542-0828 | 0609-0800 | 0638-0714 | 0707-0626 | 0641-0446 | 0711-0435  12

 13  0543-0828 | 0610-0759 | 0639-0712 | 0708-0624 | 0642-0445 | 0712-0436  13
 14  0544-0827 | 0611-0758 | 0640-0711 | 0709-0623 | 0643-0444 | 0713-0436  14
 15  0544-0827 | 0612-0757 | 0641-0709 | 0710-0621 | 0644-0444 | 0714-0436  15
 16  0545-0826 | 0613-0755 | 0642-0708 | 0711-0620 | 0646-0443 | 0714-0436  16

 17  0546-0826 | 0614-0754 | 0643-0706 | 0712-0618 | 0647-0442 | 0715-0437  17
 18  0547-0825 | 0615-0752 | 0644-0704 | 0713-0617 | 0648-0442 | 0715-0437  18
 19  0547-0824 | 0616-0751 | 0644-0703 | 0714-0615 | 0649-0441 | 0716-0438  19
 20  0548-0824 | 0616-0750 | 0645-0701 | 0715-0614 | 0650-0440 | 0717-0438  20

 21  0549-0823 | 0617-0748 | 0646-0659 | 0716-0613 | 0651-0440 | 0717-0439  21
 22  0550-0822 | 0618-0747 | 0647-0658 | 0717-0611 | 0652-0439 | 0718-0439  22
 23  0551-0821 | 0619-0745 | 0648-0656 | 0719-0610 | 0653-0439 | 0718-0440  23
 24  0552-0821 | 0620-0744 | 0649-0654 | 0720-0609 | 0654-0438 | 0718-0440  24

 25  0552-0820 | 0621-0742 | 0650-0653 | 0721-0607 | 0656-0438 | 0719-0441  25
 26  0553-0819 | 0622-0741 | 0651-0651 | 0722-0606 | 0657-0437 | 0719-0441  26
 27  0554-0818 | 0623-0739 | 0652-0650 | 0723-0605 | 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 | 0626-0735 | 0655-0645 | 0726-0600 | 0701-0436 | 0720-0444  30
 31  0558-0814 | 0627-0733 |                      | 0727-0558 |                      | 0720-0445  31

 

 Snowfall

Sept 2009 to Apr 2010

City

Sept-Oct

Nov

Dec

Jan

Feb

Mar Apr

Seasonal Totals

Aurora (Central)

20.2 9.3           29.5
Brighton 18.4 8.3           26.7
Broomfield 27.2 11.8           39.0

Castle Rock 4 NE

27.5 8.7           36.2

Colorado Sprgs Airport

1.8 1.5           3.3
Denver DIA 17.2 9.3           26.5

Denver Downtown

21.4 9.0           30.4

Golden

28.3 12.9           41.2

Fort Collins

25.5 6.6           32.1

Highlands Ranch

34.4 9.7           44.1

Lakewood

20.5 9.0           29.5

Littleton

25.9 12.2           38.1

Parker

22.5 8.2           30.7

Sedalia - Hwy 67

30.0 10.0           40.0

Thornton

22.8 8.3           31.1

Westminster

21.6 13.0           34.6

Wheatridge

28.8 10.9           39.7