Heat Waves

Heat Stress

• Obviously, related to Temperature• Strong function of humidity

– Evaporative Cooling is body’s primary mechanism• Not effective at 100% RH!

• Also Radiant Energy, Wind Speed (as long as air <98.6°), and Air Pressure

• Apparent Temperature takes into account most of these

• Heat Index assumes average radiation and wind

Table 27A

 

 

Table 27A Heat-related medical problems (Source: National Weather Service)

Heat disorder Symptoms First aid

Sunburn Redness and pain; in severe cases, swelling of skin

Ointment for mild cases; dry sterile dressing if blisters break; extensive cases should be seen by physician

Heat cramps Painful spasms, usually in muscles of legs, abdomen; heavy sweating

Firm pressure on cramping muscles, or gentle massage to relieve spasms; sips of water (unless nauseous)

Heat Exhaustion Heavy sweating, weakness, cold, clammy skin; thready pulse; fainting or vomiting

Get victim out of sun; lay down, loosen clothing, apply wet cloths; fan or move to air-conditioned area; sips of water; if nausea persists, seek immediate medical attention.

Heat Stroke High body temperature (106ºF (42C) or higher); hot dry skin; rapid and strong pulse; possible unconsciousness

Move victim to cool area; cold bath sponging; remove clothing; use fan or air-conditioning; do not give fluids; seek immediate medical emergency aid.

Table 27.1

 

 

Figure 27.1

Finally, Severe Weather that College Station is good at!

It’s getting hot in here,

cause we ain’t got no lows.

NWS Products

• Heat Advisory– Threshold Varies (e.g. PHX vs. BOS)– Two or more consecutive days

• Excessive Heat Warning – Prolonged

Table 27.2

 

 

 Western United States (Seattle region)Heat advisory May 1 through June 30: Maximum heat index 98 to 105F for one day or longerJuly 1 through Sept. 30: Maximum heat index 100 to 105F for one day or longerExcessive heat warning One of two conditions must be met: (1) Maximum heat index 106F or higher for 3 hours or more for two consecutive days, and a minimum heat index of 90F or higher at night (2) Maximum heat index of 115F or higher regardless of duration or nighttime minimum

Central United States (Chicago region)Heat advisoryMaximum heat index of 105 to 110F with a minimum of 75F or higher for two or more consecutive daysExcessive heat warningOne of three conditions must be met:(1) Three consecutive days with maximum heat index 100 to 105F with (a) at least 85 percent sunshine on two of the days, or (b) minimum heat index of 75F or higher each day(2) Consecutive days with maximum heat index of 105 to 110F(3) One day with the maximum heat index greater than 110F 

Table 27.2 Examples of criteria for issuance of heat advisories and excessive heat warnings by the National Weather Service

The four horsemen of the hotalypse…

• Upper-air ridge/far northern Jet Stream• Surface Heating: Subsidence

– SFC High is generally found_____ of the warmest air

• Dry Ground in feedback to drought– Note: High humidity keeps the max temps down a bit,

but at what cost?

• Lack of Mixing– Strong Inversion trapping warm and humid air

Figure 27.2

Figure 27.3

Warm Air Dome

Figure 27.4

Figure 27.5

Urban Heat IslandLow Evap/Transpiration, Storage of Heat In Concrete and asphalt, heat generators like cars, building “canyons” increase radiative efficiency

Figure 27.6

Memorable Heat Waves:

Read all about it…

27.7

27.8

27.9

27.10

27.11

27.12

Figure 27.7

Figure 27.8

Figure 27.9

Figure 27.10

Figure 27.11

Figure 27.12

Figure 27.13

Figure 27.14

Figure 27.15

Figure 27.16

Figure 27A

Figure 27B

Figure 27C

Table 27.3

 

 

Table 27.3: Dewpoint records set during July 1995 heat wave. Periods of record extend back to the middle or late 1940s in all cases (courtesy of Kenneth Kunkel and the American Meteorological Society).

Cleveland, Ohio 82 79

Columbia, Missouri 82 80

Eau Claire, Wisconsin 80 79

Flint, Michigan 80 79

Green Bay, Wisconsin 81 80

Moline, Illinois 82 80

Madison, Wisconsin 81 80

Rockford, Illinois 83 80

St. Louis, Missouri 83 82

Toledo, Ohio 80 79

City1995 Dewpoint

Temperature (F)Previous Record for Dewpoint

Temperature (F)

Table 27.4

 

 

Table 27.4: Hottest 4-day periods on record in Chicago, Illinois (courtesy of Kenneth Kunkel and the American Meteorological Society).

1114 July 1936 89.4 64.6 91.6 109.0

2124 July 1934 88.9 66.2 94.5 114.1

1215 July 1995 88.5 73.8 96.7 118.6

14 August 1988 87.4 71.6 93.4 111.0

28June1July1931 87.3 72.0 93.6 112.5

710 July 1936 86.7 63.5 91.6 108.7

Dates4 day mean

temperature (ºF)

4 day mean dewpoint

temperature (ºF)

4 day mean apparent

temperature (ºF)

Maximum apparent

temperature (ºF)