1. NOAA’s National Weather Service
Heat Prediction
Gregory Lundeen
Science and Operations Officer
Weather Forecast Office El Paso Area
July 13, 2016
NOAA’s National Weather Service

2. Heat Prediction Heat Wave Defined Heat Climatology Heat Prediction
Heat Advisory / Warning
Addendum
This presentation will come in four parts: Heat definition, heat climatology, heat prediction, and heat warnings/advisories. An addendum to the presentation will provide extra information on products that National Weather Service can provide but will not fit within the time limits of this presentation.

3. Heat Wave
Definition:
General – A prolonged period of abnormally hot weather relative to normal temperatures for that time of year.
Technical – A period of 48 hours during which neither the overnight low nor the daytime heat index (or temperature) falls below NWS heat stress thresholds of 80F to 105 F.
Definitions of a heat wave

4. Heat Wave Main meteorological signature of a heat wave
Slow moving or nearly stationary high pressure aloft sets up conditions favorable for the development of heat waves due to sinking air under the high pressure dome.
Main meteorological signature of a heat wave

5. Heat Wave Neccessary Conditions in the El Paso area:
Subtropical high pressure aloft (Chihuahuan High) positioned just over or south the local area. If the high is too far east – Monsoonal Flow occurs and temperatures fall.
Warmest Temperatures along the west side of the dome of high pressure.
Dry atmospheric conditions (low humidity), sometimes with a southwest to west flow at the surface.
Mostly likely occurrence June & July
While some slight differences may occur from year to year, strong high pressure aloft and relatively drier conditions in the lower levels of the atmosphere are needed to generate a heat wave conditions in the El Paso area. These conditions are mostly likely to occur in the June and July time frame but could earlier in May or as late as September.

6. Heat & Heat Index For humidity values less than 40% the
NWS heat index chart. Dangerous Heat conditions occur at around 105 degrees for either Heat Index or actual Temperatures. For the El Paso area low humidity values often accompany high temperatures. Therefore, temperatures are used in place of the heat index.
For humidity values less than 40% the
actual temperature replaces the heat index.
Temperatures are used in the El Paso area.

7. Heat Climatology Months for 100 Degree Days:
Month # Days Percent High Date
May %
June %
July %
August %
September %
Earliest - May 8th Latest - September 15th
June and July are the peak months for high heat. The all time high temperature at El Paso was 114 degrees, set in 1994 on June 30th. Every year has had at least one 100 degree day had the most 100 degree days at 62.

8. Heat Climatology
Over the past 131 years the average number of 100 degree days is 15. The average number of 100 degree days have been increasing recently with an average 22 days of 100 or higher in the past 30 years. Possible factors in this increase may include climate change and increased urbanization of the El Paso metro area (heat island effect).

9. Heat Warning/Advisory
Excessive Heat Warning—Take Action! issued within 12 hours of the onset of extremely dangerous heat conditions. Criteria - maximum temperature is expected to be 110° or higher for at least 2 days and night time air temperatures will not drop below 75°. Excessive Heat Watches—Be Prepared !Heat watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. Heat Advisory—Take Action! issued within 12 hours of the onset of dangerous heat conditions. Criteria - maximum temperature is expected to be 105° or higher for at least 2 days, and night time air temperatures will stay above 75°. Excessive Heat Outlooks -issued when the potential exists for an excessive heat event in the next 3-7 days.

10. Heat Warning/Advisory
Heat warning/advisory is not uniform across the country due to differences in the types of weather and general climatology across the country. This map indicates the thresholds for heat warnings/criteria for NWS Southern Region Offices.

11. Heat Prediction Forecast Tools:
Climatology – mostly likely period June-July
Climate Prediction Center (CPC) Provides Long Term Seasonal Outlooks out to 2 years.
NCEP - NWS Numerical Models produce data out to as much as 16 days.
Weather Prediction Center (WPC) issues national outlooks through 7 days.
Local NWS forecast office issues area specific forecasts through 7 days.
Climatology establishes the most likely period for heat waves which is June and July. The Climate Prediction Center uses long range models to predict long term trends in the weather which can be used in conjunction with climatology to get a general sense of whether warm seasons will be above or below normal. The NWS runs a variety of numerical models that can predict temperatures as well other weather effects out to as long as 16 days. The Weather Prediction Center and local Weather Offices use this information, experience and expertise to formulate forecasts out through 7 days and sometimes longer.

12. Climate Prediction Center
Examples of the kind of information you can find on the Climate Prediction Center’s web site.
CPC provides long term outlooks and trends.

13. Climate Prediction Center
This 3 month outlook covers July, August, and September. It indicates the expected trends in temperatures and probability percentages. The El Paso area will have between a 40 and 50 percent chance of warmer than normal temperatures for the 3 month period.
CPC 3 month outlook for temperature probability

14. Climate Prediction Center
This 1 month outlook covers July. It indicates the expected trends in temperatures and probability percentages. The El Paso area will have between a 30 and 40 percent chance of warmer than normal temperatures for July.
CPC 1 month outlook for temperature probability

15. Climate Prediction Center
This is CPC’s shorter range outlook of 8 to 14 days. It uses a combination of climate model and weather model data to provide a trend, which indicates warmer than normal temperatures.
CPC 8 to 14 day outlook for temperature probability

16. NWS Meteorological Models
The NWS runs many forecast models to help predict trends in the weather. The GFS model is one of the NWS mainline models and provides detailed information on temperatures, moisture, precipitation, winds and a variety of other meteorological information.
Global Forecast System (GFS) Model Temperature.
Data provided out to 16 days with skill out to 8 days.

17. Weather Prediction Center
WPC maximum heat index forecast

18. Local Weather Office WFO El Paso Forecast Products (out to 7 Days)
Area Forecast Discussion (AFD)
Zone Forecast Discussion (ZFP)
Hazardous Weather Outlook (HWO)
Point Forecast Matrix (PFM)
State Forecast Table (SFT)
Graphical Forecasts (NDFD) (collaborated)
Graphicasts (for Web Page, Facebook, etc)
Weather Hazards Outlook & Matrix (for IDSS)
Heat Advisory / Warning (NPW)
A list of products the NWS WFO El Paso produces on a regular basis.

19. Local forecasts available on our webpage
Forecast Products
Most of our local forecast products are available on our web page as well as a variety of other products.
Local forecasts available on our webpage
weather.gov/epz

20. Forecast Products Gridded Forecast (NDFD) describes the
Gridded forecast is locally updated and merged with a national digital forecast database from other weather offices which is accessible on the web.
Gridded Forecast (NDFD) describes the
weather in picture format out through 7 days

21. NWS Product Dissemination
NOAA Weather Wire Service
NOAA Weather Radio
Web Pages
Facebook
Twitter
TV, Radio and Print Media
Decision Support to Core Partners
The NWS will use a variety of outlets to get weather information to the public.

22. Wrap Up Questions to consider:
What additional information do you need?
Are the Advisory/Warning thresholds adequate?
What lead times do you need?
What resources would you like the NWS provide?

23. Thank You For Your Time!
National Weather Service Forecast Office El Paso Area 7955 Airport Road Santa Teresa NM Phone: Fax: Web Page: weather.gov/epz Facebook:

24. Addendum Useful Web Page Links
More information on local forecast products
NWS heat safety tips

25. Useful Web Page Links weather.gov weather.gov/epz www.ncep.noaa.gov
climate.gov

26. Forecast Products Area Forecast Discussion Product that
Describes current
weather patterns
and conditions.
It discusses
what to expect over
the next seven days.

27. Forecast Products Point Forecast Matrices Product that lists specific
Values for a
Specific area
Out through
7 days.

28. Forecast Products Hazardous Weather Outlook describes any
expected hazardous weather
(including heat) out through 7 days

29. Text based product that forecasts
Forecast Products
Zone Forecast
Product
Text based product that forecasts
expected weather at
specific regions
within the area
through 7 days.

30. Forecast Products Web Page
Forecast on the local web page.

31. Graphicasts
An example of WFO El Paso weather office graphicast emphasizing heat

32. Climate.gov
A useful site that provides additional links to climate information and outlooks.

33. Heat Safety Tips Web Page
Main page of NWS heat safety

34. Heat Safety Tips
Heat Safety Tips

35. Heat Safety Tips
Heat exhaustion and heat stroke information

36. Local Heat Safety Tips
Locally produced graphicast emphasizing heat safety.