CWS 4B

3D"{short

HEATING DEGREE-DAYS AND WIND CHILL

Do Now:

Print this file.
Print the associated Curr= ent Weather Studies B Image 1 File. Change your printer to "landscape" setting be= fore printing.
Print the Daily Summary and/or Supplemental Information Files, if directed by your instructor.=

To Complete Investigation:

Reference: Chapter 4 in t= he Weather Studies textbook.
Complete Investigation 4B= in the Weather Studies Investigations Manual as directed by your instructor.
Complete this Wednesday online-delivered Current Weather Studies 4B activity if directed by yo= ur instructor.

1= . Heating and Cooling Degree Days and wind chill values are calculated with the use of observational data collected at weather stations. The Wednesday, 30 Septemb= er 2009, Supplemental Information File on the course website lists pages where= you can compare Heating and Cooling Degree Day units for the season in your are= a. At this writing, data for these major cities are current through August. An= nual totals of Heating Degree Days are accumulated beginning 1 July while Cooling Degree Days begin with 1 January.

Image 1 is a NWS map of maximum and minimum temperatures, in degrees Fahrenhe= it, at selected stations across the U.S. during the 24-hour period ending at 12Z on Tuesday, 29 September 2009. In color, the red upper number is the period's maximum temperature and the blue lower number the minimum at the station denoted by the green dot. For the contiguous U.S., not surprisingly, temperatures near the western Great Lakes were among the coolest with Duluth, = Minnesota and Wausau, Wisconsin being the station= s on this map reporting the lowest maximum temperature for the dat= e. The maximum temperature reported at Duluth= and Wausau during the= 24 hours was [(62)(59)(53)] °F. The minimum temperatures there were 40 °F and 43 °F, respectively. Recall from the Monday, Current Weather Study 4A, a cold air = mass was invading that region following the cold front bringing cold air advecti= on to those stations.

2= .      The lowest minimum temperature on the map was 30 °F reported = at [(Minneapolis, MN)(Valentine, NE)(= Denver, = CO)].

3= .      On the warmer side, the highest maximum temperature was a torrid= 106 °F at Phoenix, = Arizona while their minimum dropped to= 74 °F. However, the highest reported minimum temperature for= the period in the coterminous U.S. occurred at Key West, Florida, where it only dropped down to [(71)(75)(81)]= °F.

4= .      Based on Phoenix's maximum and minimum, the mean temperature at Phoenix was [(76)(83)(= 90)] °F.

5= .      The number of degree days accumulated in Phoenix was [(4)(14)(<= u>25)].

6= .      The mean temperature derived from the maximum and minimum temperatures at Phoenix indicates= [(heating)(cooling)] degree day units were accumulated.

Refer to Image 1 to answer the following questions, keeping in mind that= the base of 65 °F is used to determine whether Heating Degree Day units or Cooling Degree Day units, if any, were produced and how many. Also, follow = the NWS practice that, if necessary, the mean daily temperature is rounded <= i>up to the nearest whole degree before calculating HDD or CDD.

7= . Fargo, on the ND-= MN border experienced a mean temperature of [(39)(46)(51)] °F.

8= . Therefore, Fargo accumulated [(8)(12)(19)(24)] HDD units on that day.

9= . Philadelphia, PA with a high of 79 °F experienced a mean temperature of [(58)(66)(71)] °F.

1= 0. Philadelphia had = 1 [(HDD)(CDD)] as a result.

1= 1. A loc= ation on the map that did not accumulate either Heating or Cooling Degrees Day un= its was [(St. Louis, MO)(Reno, NV)(Portland, ME)].

1= 2. Scann= ing the map's maximum and minimum temperatures, it can be inferred that utility energy usage in the U.S. during this daily period was probably more needed for heating across the [(north-central)(= southwestern)(southeastern)] portion of the U.S.<= /st1:place> You might note the maxima and minima for Prudhoe Bay<= /st1:City>, Alaska (28 and 13 respectively), tempera= tures that will only continue to drop with the shorter days and lower sun along t= he "North Slope".

1= 3. The N= WS map of highest and lowest temperatures can be accessed from the course website.= Go to the website, scroll down to Climate and click on the "Nation= al Temps/Precip." link. When viewing the NWS = page with the latest map, go to the "Max/Min Temperatures" option bar = to the upper left of the map and click on the down arrow. The list of temperat= ure dates displayed shows that, including the current day's map, you can access max/min temperature maps for a total of 7 days. Similarly, using the same option bar, one can highlight any of the current or past six days' maps of = [(precipitation)(wind speed)] which can be acquired= by then pressing GO. The option bar to the upper right provides future climate outlooks.

Also back on the course website, Climate section, there is a link= to "Local NWS Offices". That link provides a map of local National Weather Service Offices. Click on the yellow circle of your closest NWS Off= ice; the webpage of that NWS Forecast Office appears. In the menu along the left side of the page is an option for "Climate" information and a lin= k to "Local" for climatic information in various forms for one or more cities in the office's service area. Choosing (1) Product: Daily Climate Report (CLI), (2) Location, (3) Most Recent (yesterday's), or archived choice, then (4) GO. The new page will provide the requested day's climatic data for the station showing maximum, minimum and average temperatures as w= ell as heating and cooling degree days for that date and the season. You can see your local data (without the arithmetic!) for the season.

HDD values and their effect on homeowners' heating bills will likely bec= ome an issue for many in the country as heating costs become another stress to tight budgets. You might follow these HDD values as we progress through fall and into winter.

1= 4. Heati= ng and Cooling Degree Day units reflect energy needs to attain indoor human comfor= t. Outdoors the cooling effect of wind along with temperature on an individual= is reflected by using the windchill equivalent temperature. The Image 1 map shows that the minimum temperature at Valentin= e, Nebraska was 30 = °F. Assume that Valentine was experiencing a wind speed of 10 miles per hour wh= en the temperature was 30 °F. Using the windchill equivalent temperature (WET) Table in Figure 4 of the Weather Studies Investigations Manual Investigation 4B, the WET for this combination of temperature and wind speed would have been [(15)(17<= /u>)(21)(25)] °F.

If directed by your instructor, place the answers to Investigation 4B and Current Weather Studies 4B on the B Answer Form linked from the AMS Weather Studies website.

©Copyright 2009, American Meteorological Society