NOAA Technical Memorandum NWS WR-215 WEATHERTOOLS Tom
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A Winter Forecasting Handbook Winter Storm Information That Is Useful to the Public
A Winter Forecasting Handbook Winter storm information that is useful to the public: 1) The time of onset of dangerous winter weather conditions 2) The time that dangerous winter weather conditions will abate 3) The type of winter weather to be expected: a) Snow b) Sleet c) Freezing rain d) Transitions between these three 7) The intensity of the precipitation 8) The total amount of precipitation that will accumulate 9) The temperatures during the storm (particularly if they are dangerously low) 7) The winds and wind chill temperature (particularly if winds cause blizzard conditions where visibility is reduced). 8) The uncertainty in the forecast. Some problems facing meteorologists: Winter precipitation occurs on the mesoscale The type and intensity of winter precipitation varies over short distances. Forecast products are not well tailored to winter Subtle features, such as variations in the wet bulb temperature, orography, urban heat islands, warm layers aloft, dry layers, small variations in cyclone track, surface temperature, and others all can influence the severity and character of a winter storm event. FORECASTING WINTER WEATHER Important factors: 1. Forcing a) Frontal forcing (at surface and aloft) b) Jetstream forcing c) Location where forcing will occur 2. Quantitative precipitation forecasts from models 3. Thermal structure where forcing and precipitation are expected 4. Moisture distribution in region where forcing and precipitation are expected. 5. Consideration of microphysical processes Forecasting winter precipitation in 0-48 hour time range: You must have a good understanding of the current state of the Atmosphere BEFORE you try to forecast a future state! 1. Examine current data to identify positions of cyclones and anticyclones and the location and types of fronts. -
* Corresponding Author Address: Mark A. Tew, National Weather Service, 1325 East-West Highway, Silver Spring, MD 20910; E-Mail: [email protected]
P1.13 IMPLEMENTATION OF A NEW WIND CHILL TEMPERATURE INDEX BY THE NATIONAL WEATHER SERVICE Mark A. Tew*1, G. Battel2, C. A. Nelson3 1National Weather Service, Office of Climate, Water and Weather Services, Silver Spring, MD 2Science Application International Corporation, under contract with National Weather Service, Silver Spring, MD 3Office of the Federal Coordinator for Meteorological Services and Supporting Research, Silver Spring, MD 1. INTRODUCTION group is called the Joint Action Group for Temperature Indices (JAG/TI) and is chaired by the NWS. The goal of The Wind Chill Temperature (WCT) is a term used to JAG/TI is to internationally upgrade and standardize the describe the rate of heat loss from the human body due to index for temperature extremes (e.g., Wind Chill Index). the combined effect of wind and low ambient air Standardization of the WCT Index among the temperature. The WCT represents the temperature the meteorological community is important, so that an body feels when it is exposed to the wind and cold. accurate and consistent measure is provided and public Prolonged exposure to low wind chill values can lead to safety is ensured. frostbite and hypothermia. The mission of the National After three workshops, the JAG/TI reached agreement Weather Service (NWS) is to provide forecast and on the development of the new WCT index, discussed a warnings for the protection of life and property, which process for scientific verification of the new formula, and includes the danger associated from extremely cold wind generated implementation plans (Nelson et al. 2001). chill temperatures. JAG/TI agreed to have two recognized wind chill experts, The NWS (1992) and the Meteorological Service of Mr. -
Yeah, There Is a Difference Measuring Road Weather and Using It!
Yeah, There is a Difference Measuring Road Weather and Using it! Jon Tarleton Head of Transportation Marketing – Meteorologist Twitter: @jontarleton What are we going to talk about? . The weather of course! But when and what matters! . The weather before, during, and after a storm. The weather around frost. Let’s start with nothing and build on it. When we are done you will know what information is good information! Page 2 © Vaisala 10/20/2016 [Name] There is weather… And then there is road weather… Page 3 © Vaisala 10/20/2016 [Name] Let’s start at the beginning! Page 4 © Vaisala 10/20/2016 [Name] You just got your fleet of new plows! Page 5 © Vaisala 10/20/2016 [Name] But otherwise you are Anytown, USA Page 6 © Vaisala 10/20/2016 [Name] Approaching winter storm Page 7 © Vaisala 10/20/2016 [Name] Air temperature .Critical in telling us the type of precipitation. .How do we measure it? .Measured from 6ft off the ground .In a white vented enclosure .Combined with wind it has an impact on our road surface. Page 8 © Vaisala 10/20/2016 [Name] Thermodynamics 101 .To understand how the air impacts our pavement we must understand how heat transfers from objects, and between the air and objects. Sun Air Subgrade Page 9 © Vaisala 10/20/2016 [Name] Wind Page 10 © Vaisala 10/20/2016 [Name] Wind – An important piece of the weather . Lows typical move from southwest to northwest. System may not always contain all of the precipitation types. Best snow is usually approx. L 250 miles north of center of low. -
Weather Elements
In this chapter Temperature Humidity Clouds Precipitation WEATHER ELEMENTS TEMPERATURE per cent of the incoming radiation. The more energy a surface absorbs, the more heat it will eventually release Heat is one form of energy. The sun radiates energy in back into the atmosphere. waves, in this case short waves, to the earth. The atmosphere does not absorb short-wave energy readily. The clouds, dust and water vapour in the atmosphere To show your students that the rate at which energy is absorbed depends on the colour of a deflect about half of the sun's energy back into space. material, try Activity number 7 on page 8-9 in What passes through is absorbed by the land and water the Activity Section. and converted to heat. The earth radiates this back as Eventually, all the energy the sun radiates to earth long-wave energy, which then warms the air above. In returns to outer space creating the global balance of short, the earth acts as a radiator, which you probably energy. This prevents the earth from heating up or know already, if you have ever walked down a long stretch cooling down. of sidewalk or across a large parking lot on a hot day and watched (or felt) the heat rise from the pavement. The temperature on your thermometer this morning, however, was probably affected more by the season, the Several factors affect how much of the sun's energy a time of day, the latitude, and the geography of your area surface, such as a field, absorbs. One is its colour. -
NOTES and CORRESPONDENCE the Steadman Wind Chill
DECEMBER 1998 NOTES AND CORRESPONDENCE 1187 NOTES AND CORRESPONDENCE The Steadman Wind Chill: An Improvement over Present Scales ROBERT G. QUAYLE National Climatic Data Center, Asheville, North Carolina ROBERT G. STEADMAN School of Agricultural Science, La Trobe University, Bundoora, Victoria, Australia 19 February 1998 and 24 June 1998 ABSTRACT Because of shortcomings in the current wind chill formulation, which did not consider the metabolic heat generation of the human body, a new formula is proposed for operational implementation. This formula, referred to as the Steadman wind chill, is based on peer-reviewed research including a heat generation and exchange model of an appropriately dressed person for a range of low temperatures and wind speeds. The Steadman wind chill produces more realistic wind chill equivalents than the current NWS formulation. It is easy to determine from tables (calculated by application of a quadratic ®t in both U.S. and metric units) with values accurate to within 18C. 1. Introduction freezing water to actually freeze under various wind and temperature conditions rather than any human physio- Many scientists have noted de®ciencies in the current logical model of heat loss and gain under equivalent wind chill scale (e.g., Court 1992; Dixon and Prior 1987; conditions. The major consequence is that water, not Driscoll 1985, 1992, 1994; Kessler 1993, 1994, 1995; having a metabolic heat source and not being appro- Horstmeyer 1994; Osczevski 1995; Schwerdt 1995; priately attired in human clothing, produces colder wind Steadman 1995). There was a session partly devoted to chills (for given wind and temperature conditions) than this topic at the 22d Annual Workshop on Hazards Re- those experienced by live, clothed humans. -
Martian Windchill in Terrestrial Terms Randall Osczevski
MARTIAN WINDCHILL IN TERRESTRIAL TERMS RANDALL OSCZEVSKI A two-planet model of windchill suggests that the weather on Mars is not nearly as cold as it sounds. he groundbreaking book The Case for Mars (Zubrin 1996) advocates human exploration and colonization of the red planet. One of its themes is that Mars is beset by dragons of the sort T that ancient mapmakers used to draw on maps in unexplored areas. The dragons of Mars are daunting logistical and safety challenges that deter human exploration. One such dragon must surely be its weather, for Mars sounds far too cold for human life. No place on Earth experiences the low temperatures that occur every night on Mars, where even in the tropics in summer the thermometer often reads close to –90°C and, in midlatitudes in winter, as low as –120°C. The mean annual temperature of Mars is –63°C (Tillman 2009) com- pared to +14°C on Earth (NASA 2010). We can only try to imagine how cold the abysmally low temperatures of Mars might feel, especially when combined with high speed winds Left: The High Arctic feels at least as cold as Mars, year round (Photo by R. Osczevski 1989). Right: Twin Peaks of Mars. (Photo by NASA, Pathfinder Mission 1997) AMERICAN METEOROLOGICAL SOCIETY APRIL 2014 | 533 Unauthenticated | Downloaded 09/30/21 08:37 PM UTC that sometimes scour the planet. This intensely bone- refer to the steady state heat transfer from the upwind chilling image of Mars could become a psychological sides of internally heated vertical cylinders having the barrier to potential colonists, as well as to public same diameter, internal thermal resistance, and core support for such ventures. -
Aviation Weather Services (AC 00-45H)
U.S. Department Advisory of Transportation Federal Aviation Administration Circular Subject: Aviation Weather Services Date: 1/8/18 AC No: 00-45H Initiated by: AFS-400 Change: 1 1 PURPOSE OF THIS ADVISORY CIRCULAR (AC). This AC explains U.S. aviation weather products and services. It provides details when necessary for interpretation and to aid usage. This publication supplements its companion manual, AC 00-6, Aviation Weather, which documents weather theory and its application to aviation. The objective of this AC is to bring the pilot and operator up-to-date on new and evolving weather information and capabilities to help plan a safe and efficient flight, while also describing the traditional weather products that remain. 2 PRINCIPAL CHANGES. This change adds guidance and information on Graphical Forecast for Aviation (GFA), Localized Aviation Model Output Statistics (MOS) Program (LAMP), Terminal Convective Forecast (TCF), Polar Orbiting Environment Satellites (POES), Low-Level Wind Shear Alerting System (LLWAS), and Flight Path Tool graphics. It also updates guidance and information on Direct User Access Terminal Service (DUATS II), Telephone Information Briefing Service (TIBS), and Terminal Doppler Weather Radar (TDWR). This change removes information regarding Area Forecasts (FA) for the Continental United States (CONUS). 1/8/18 AC 00-45H CHG 1 PAGE CONTROL CHART Remove Pages Dated Insert Pages Dated Pages iii thru xii 11/14/16 Pages iii thru xiii 1/8/18 Pages 1-8 and 1-9 11/14/16 Page 1-8 1/8/18 Page 3-57 11/14/16 Pages 3-57 thru -
Driving in the Winter Factsheet
Driving in the Winter FactSheet HS04-010B (9-07) Even in Texas the onset of winter can bring severe • Winter Storm Watch winter weather conditions. Employers and employees alerts the public to the who drive for a living need to be aware of how to possibility of a blizzard, drive in winter weather. The leading cause of death heavy snow, freezing rain, during a winter storm is driving accidents and multiple or heavy sleet. vehicle accidents are more likely in severe winter weather conditions. Employers and employees can • Winter Storm Warning is take steps to increase safety while driving in winter issued when a combination of heavy snow, heavy weather. freezing rain, or heavy sleet is expected. • Plan ahead and allow plenty of time for travel. • Winter Weather Advisories are issued when An employer should maintain information on its accumulations of snow, freezing rain, freezing employees’ driving destinations, driving routes, drizzle, and sleet may cause significant and estimated time of arrivals. Drivers should inconvenience and moderately dangerous be patient while driving, because trip time can conditions. increase in winter weather. • Snow is frozen precipitation formed when • Winterize vehicles before traveling in winter temperatures are below freezing in most of the weather. Before driving have a mechanic atmosphere from the earth’s surface to cloud check the following items on vehicles: battery; level. antifreeze; wipers and windshield washer fluid; ignition system; thermostat; lights; flashing • Sleet, also know as ice pellets, is formed when hazard lights; exhaust system; heater; brakes; precipitation or raindrops freeze before hitting defroster; tires (check for adequate tread); and the ground. -
On the Use of Radiosondes in Freezing Precipitation
MARCH 2018 W AUGH AND SCHUUR 459 On the Use of Radiosondes in Freezing Precipitation SEAN WAUGH NOAA/OAR/National Severe Storms Laboratory, and Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, Norman, Oklahoma TERRY J. SCHUUR Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and NOAA/OAR/National Severe Storms Laboratory, Norman, Oklahoma (Manuscript received 13 April 2017, in final form 4 January 2018) ABSTRACT Radiosonde observations are used the world over to provide critical upper-air observations of the lower atmosphere. These observations are susceptible to errors that must be mitigated or avoided when identified. One source of error not previously addressed is radiosonde icing in winter storms, which can affect forecasts, warning operations, and model initialization. Under certain conditions, ice can form on the radiosonde, leading to decreased response times and incorrect readings. Evidence of radiosonde icing is presented for a winter storm event in Norman, Oklahoma, on 24 November 2013. A special sounding that included a particle imager probe and a GoPro camera was flown into the system producing ice pellets. While the iced-over temperature sensor showed no evidence of an elevated melting layer (ML), complementary Particle Size, Image, and Velocity (PASIV) probe and polarimetric radar observations provide clear evidence that an ML was indeed present. Radiosonde icing can occur while passing through a layer of supercooled drops, such as frequently found in a subfreezing layer that often lies below the ML in winter storms. Events that have warmer/deeper MLs would likely melt any ice present off the radiosonde, minimizing radiosonde icing and allowing the ML to be detected. -
The Basis of Wind Chill RANDALL J
ARCTIC VOL. 48, NO. 4 (DECEMBER 1995) P. 372– 382 The Basis of Wind Chill RANDALL J. OSCZEVSKI1 (Received 21 June 1994; accepted in revised form 16 August 1995) ABSTRACT. The practical success of the wind chill index has often been vaguely attributed to the effect of wind on heat transfer from bare skin, usually the face. To test this theory, facial heat loss and the wind chill index were compared. The effect of wind speed on heat transfer from a thermal model of a head was investigated in a wind tunnel. When the thermal model was facing the wind, wind speed affected the heat transfer from its face in much the same manner as it would affect the heat transfer from a small cylinder, such as that used in the original wind chill experiments carried out in Antarctica fifty years ago. A mathematical model of heat transfer from the face was developed and compared to other models of wind chill. Skin temperatures calculated from the model were consistent with observations of frostbite and discomfort at a range of wind speeds and temperatures. The wind chill index was shown to be several times larger than the calculated heat transfer, but roughly proportional to it. Wind chill equivalent temperatures were recalculated on the basis of facial cooling. An equivalent temperature increment was derived to account for the effect of bright sunshine. Key words: bioclimatology, cold injuries, cold weather, convective heat transfer, face cooling, frostbite, heat loss, survival, wind chill RÉSUMÉ. La popularité de l’indice de refroidissement du vent a souvent été expliquée par le fait qu’on peut la relier plus ou moins à l’effet du vent sur le transfert thermique à partir de la peau nue, le plus souvent celle du visage. -
Appendix a Gempak Parameters
GEMPAK Parameters APPENDIX A GEMPAK PARAMETERS This appendix contains a list of the GEMPAK parameters. Algorithms used in computing these parameters are also included. The following constants are used in the computations: KAPPA = Poisson's constant = 2 / 7 G = Gravitational constant = 9.80616 m/sec/sec GAMUSD = Standard atmospheric lapse rate = 6.5 K/km RDGAS = Gas constant for dry air = 287.04 J/K/kg PI = Circumference / diameter = 3.14159265 References for some of the algorithms: Bolton, D., 1980: The computation of equivalent potential temperature., Monthly Weather Review, 108, pp 1046-1053. Miller, R.C., 1972: Notes on Severe Storm Forecasting Procedures of the Air Force Global Weather Central, AWS Tech. Report 200. Wallace, J.M., P.V. Hobbs, 1977: Atmospheric Science, Academic Press, 467 pp. TEMPERATURE PARAMETERS TMPC - Temperature in Celsius TMPF - Temperature in Fahrenheit TMPK - Temperature in Kelvin STHA - Surface potential temperature in Kelvin STHK - Surface potential temperature in Kelvin N-AWIPS 5.6.L User’s Guide A-1 October 2003 GEMPAK Parameters STHC - Surface potential temperature in Celsius STHE - Surface equivalent potential temperature in Kelvin STHS - Surface saturation equivalent pot. temperature in Kelvin THTA - Potential temperature in Kelvin THTK - Potential temperature in Kelvin THTC - Potential temperature in Celsius THTE - Equivalent potential temperature in Kelvin THTS - Saturation equivalent pot. temperature in Kelvin TVRK - Virtual temperature in Kelvin TVRC - Virtual temperature in Celsius TVRF - Virtual -
ENVIRONMENTAL METER [email protected] 1.800.561.8187
USER MANUAL ENVIRONMENTAL METER Model EN510 Additional User Manual Translations available at 1.800.561.8187 www. .com [email protected] Introduction Thank you for selecting the Extech EN510 Environmental Meter. This instrument measures Air Velocity with Air temperature, Air Flow (volume), Light, Relative Humidity % with Air temperature, Dew Point temperature, Web bulb temperature, Type K temperature (external probe), Heat Index temperature, and Wind Chill temperature. The backlit LCD includes primary and secondary displays plus a variety of intuitive status indicators. This device is shipped fully tested and calibrated and, with proper use, will provide years of reliable service. Please visit our website ( ) to check for the latest version and translations of this User Manual, Product Updates, Product Registration, and Customer Support. Features • Professional environmental meter with programming menu for user-customization • Selectable units of measure • Air velocity with air temperature readings • Air Flow (Volume) measurements in CFM (ft3) and CMM (m3) units • Light measurements in Foot candle and LUX units • Environmental measurements: Relative humidity % with air temperature, Dew point temperature, Wet bulb temperature, Wind chill temperature, Heat Index temperature, and Type K temperature (with external probe connected) • Low-friction ball bearing mounted vane wheel for high accuracy low air velocity measurements • Built-in barometric sensor for precise atmosphere and altitude monitoring • MAX-MIN Recording • Display Hold freezes displayed reading for convenience • Compact, light-weight, easy-to-use, ergonomic design with lanyard • Backlit LCD automatically reverses orientation to match selected sensor mode Safety • Please read the entire User Manual and Quick Start before operating this device. • Use the meter only as specified and do not attempt to service or open the meter housing.