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234 Pages·2003·9 MB·English

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REVIEW AND APPROVAL PAGE
AFWA/TN-98/002, Meteorological Techniques, 13 June 2003, has been reviewed and is
approved for public release. There is no objection to unlimited distribution of this document to the
public at large, or by the Defense Technical Information Center (DTIC) to the National Technical
Information Service (NTIS).
MARK T. SURMEIER, GS-14, DAF
Acting Director, Air and Space Science
JOHN D. GRAY, GS-13, DAF
Scientific and Technical Information
Program Manager
ii
REPORT DOCUMENTATION PAGE
2. Report Date: 13 June 2003
3. Report Type: Technical Note
4. Title: Meteorologial Techniques
6. Authors: Mark R. Mireles, Capt Kirth L. Pederson, MSgt Charles H. Elford.
7. Performing Organization Names and Address: Air Force Weather Agency
(AFWA), Offutt AFB NE 68113-4039
8. Performing Organization Report Number: AFWA/TN–98/002 Revised
12. Distribution/Availability Statement: Approved for Public Release;
Distribution is Unlimited.
13. Abstract: Contains weather forecasting techniques of interest to military
meteorologists, in three chapters: surface weather elements, flight weather
elements, and convective weather. Includes both general specific rules of thumb,
results of research, lessons learned from experience, etc, gathered from military
and other sources. Updates and supersedes earlier AFWA/TN-98/002,
Meteorological Techniques.
14. Subject Terms: ATMOSPHERIC PRESSURE, ATMOSPHERIC STABILITY,
CLIMATOLOGY, CLOUDS, CONTRAILS, D-VALUES, DEW POINT,
ELECTROOPTICS, ICING, PRECIPITATION, RELATIVE HUMIDITY,
SEVERE WEATHER, SKY COVER, SOLAR WEATHER, TEMPERATURE,
THUNDERSTORMS, TORNADOES, TURBULENCE, VISIBILITY,
WEATHER, WINDS
15: Number of Pages: 233
17. Security Classification of Report: UNCLASSIFIED
18. Security Classification of this Page: UNCLASSIFIED
19. Security Classification of Abstract: UNCLASSIFIED
20. Limitation of Abstract: UL
Standard Form 298
iii
TABLE OF CONTENTS
CHAPTER 1 — SURFACE WEATHER ELEMENTS
I. VISIBILITY.......................................................................................................................1-1
A. Dry Obstructions (Lithometeors)..................................................................................1-1
B. Moist Obstructions (Hydrometeors)..............................................................................1-1
C. Visibility Forecasting Rules of Thumb .........................................................................1-3
D. Visibility Forecasting Aids/Techniques.........................................................................1-10
II. PRECIPITATION...............................................................................................................1-14
A. Precipitation General Guidance.................................................................................... 1-14
B. Model Guidance............................................................................................................1-18
C. Determining Precipitation Type .................................................................................... 1-18
D. Forecasting Rainfall Amounts.......................................................................................1-22
E. Snowfall ........................................................................................................................1-23
III. SURFACE WINDS...........................................................................................................1-35
A. Wind Basics ..................................................................................................................1-35
B. General Tools for Forecasting Surface Winds............................................................... 1-36
C. Specialized Airfield Operations Topics......................................................................... 1-46
IV. TEMPERATURE...............................................................................................................1-50
A. General Temperature Forecast Tools............................................................................. 1-50
B. Forecasting Max Temperatures .....................................................................................1-52
C. Minimum Temperature Forecasts..................................................................................1-54
D. Some Additional Rules of Thumb ................................................................................1-54
E. Temperature Indices .....................................................................................................1-55
V. PRESSURE........................................................................................................................1-61
A. General Guidance.......................................................................................................... 1-61
B. Pressure-Related Parameters........................................................................................1-62
CHAPTER 2 — FLIGHT WEATHER ELEMENTS
I. CLOUDS.............................................................................................................................2-1
A. Cloud Types/States of the Sky.......................................................................................2-1
B. General Forecasting Tools............................................................................................. 2-5
C. Cloud Forecasting Techniques. .....................................................................................2-9
II. TURBULENCE.................................................................................................................. 2-14
A. Levels of Intensity.........................................................................................................2-14
B. Aircraft Turbulence Sensitivities................................................................................... 2-15
C. Causes of Turbulence....................................................................................................2-16
D. Clear Air Turbulence (CAT).......................................................................................... 2-18
E. Mountain Wave (MW) Turbulence. .............................................................................. 2-26
F. Wake Turbulence. .......................................................................................................... 2-29
G. Gravity Waves and Stratospheric Turbulence................................................................ 2-30
H. Forecasting Aids. .......................................................................................................... 2-32
III. AIRCRAFT ICING.............................................................................................................2-39
A. Icing Formation Processes and Classification...............................................................2-39
B. Meteorological Considerations. .................................................................................... 2-45
C. Products and Procedures...............................................................................................2-49
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D. Standard System Applications. .....................................................................................2-51
E. Methods and Rules of Thumb for the “Negative 8 Times D” (-8D) Procedure. ...........2-54
F. Summary........................................................................................................................ 2-55
IV. MISCELLANEOUS WEATHER ELEMENTS................................................................2-56
A. Flight Level and Climb Winds......................................................................................2-56
B. Temperature................................................................................................................... 2-57
C. Thunderstorms. .............................................................................................................2-58
D. Contrails........................................................................................................................2-58
E. JAAWIN and Contrails. ............................................................................................... 2-58
F. Forecasting In-flight Visibility for Air-refueling Mission Execution Forecasts (MEFs).2-62
G. Cirrus Forecasting. .......................................................................................................2-63
H. Ditch Headings and Wave Height................................................................................ 2-64
I. Sea Surface Temperatures.............................................................................................2-64
J. Space Weather. .............................................................................................................2-65
K. Electrooptics. ................................................................................................................ 2-77
L. Clutter or TAWS Scene Complexity.............................................................................2-83
M. Chemical Downwind Messages ...................................................................................2-89
N. Nuclear Fallout Bulletins............................................................................................. 2-89
O. Volcanic Ash ................................................................................................................2-89
CHAPTER 3. — CONVECTIVE WEATHER
I. THUNDERSTORMS...........................................................................................................3-1
A. Thunderstorm Types .....................................................................................................3-1
II. SYNOPTIC PATTERNS....................................................................................................3-5
A. Classic Synoptic Convective Weather Patterns............................................................. 3-6
B. Additional Squall Line Information .............................................................................. 3-12
III. CONVECTIVE WEATHER TOOLS.................................................................................3-13
A. Stability Indices............................................................................................................. 3-13
B. Evaluation and Techniques. .......................................................................................... 3-21
BIBLIOGRAPHY........................................................................................................................B-1
ABBREVIATIONS AND ACRONYMS .................................................................................... A-1
GLOSSARY .................................................................................................................................G-1
SUBJECT INDEX .......................................................................................................................I-1
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LIST OF FIGURES
Figure 1-1 Whiteout Conditions -----------------------------------------------------------------------1-2
Figure 1-2 Ice Fog (Dissipating) -----------------------------------------------------------------------1-3
Figure 1-3 Pre-Frontal Fog Associated with Warm Fronts ----------------------------------------- 1-9
Figure 1-4 Post-Frontal Fog Associated with Slow-Moving Cold Fronts ------------------------1-9
Figure 1-5 Graphical Method of Forecasting Fog --------------------------------------------------- 1-10
Figure 1-6. Thermal Ribbon Spacing ------------------------------------------------------------------ 1-15
Figure 1-7 The 500-mb Product------------------------------------------------------------------------ 1-16
Figure 1-8 Widespread Precipitation Scenario ------------------------------------------------------- 1-16
Figure 1-9 Overrunning Associated with a Typical Cyclone --------------------------------------- 1-17
Figure 1-10 Equal Probability of Liquid or Frozen Precipitation ----------------------------------- 1-19
Figure 1-11 Probability of Precipitation Being Frozen Versus Liquid------------------------------ 1-19
Figure 1-12 Method 2------------------------------------------------------------------------------------- 1-20
Figure 1-13 Snow Index (200-mb) Example----------------------------------------------------------- 1-24
Figure 1-14 Centrifugal and Centripetal Forces ------------------------------------------------------- 1-35
Figure 1-15 Geostrophic Wind--------------------------------------------------------------------------- 1-36
Figure 1-16 Isallobaric Flow----------------------------------------------------------------------------- 1-36
Figure 1-17 Pressure Gradient Method for Determining Surface Winds--------------------------- 1-38
Figure 1-18a-f Variation of Isallobaric Winds by Latitude -------------------------------------------- 1-39
Figure 1-19 Open-Cell Cumulous Shapes-------------------------------------------------------------- 1-42
Figure 1-20 Low-level Wind Shear Decision Tree ---------------------------------------------------- 1-47
Figure 1-21 Temperature Forecasting Checklist Sample---------------------------------------------1-52
Figure 1-22 Computation of Maximum Temperature ------------------------------------------------ 1-53
Figure 1-23 Heat Index ----------------------------------------------------------------------------------- 1-56
Figure 1-24 Fighter Index of Thermal Stress (FITS) Chart ------------------------------------------ 1-57
Figure 1-25 Wind Chill Temperature (WCT) Index Chart with 33-Foot Garrison
Anemometer Height (degrees Celsius and knots) -------------------------------------- 1-58
Figure 1-26 Wind Chill Temperature (WCT) Index Chart with 15-Foot Garrison
Anemometer Height (degrees Celsius and knots) -------------------------------------- 1-58
Figure 1-27 Wind Chill Temperature (WCT) Index Chart with 5-Foot (handheld)
Anemometer Height (degrees Celsius and knots) --------------------------------------1-59
Figure 1-28 Wind Chill Temperature (WCT) Index Chart with 5-Foot (handheld)
Anemometer Height (degrees Fahrenheit and MPH) ---------------------------------- 1-59
Figure 1-29 Wind Chill Temperature (WCT) Index Chart with 33-Foot Garrison
Anemometer Height (degrees Fahrenheit and MPH) ----------------------------------1-60
Figure 1-30 Wind Chill Temperature (WCT) Index Chart with 33-Foot Garrison
Anemometer Height (degrees Fahrenheit and MPH) ----------------------------------1-60
Figure 1-31 Pressure Conversion Chart ---------------------------------------------------------------- 1-64
Figure 1-32 Density Altitude Computation Chart----------------------------------------------------- 1-65
Figure 1-33 D-Value Computation Chart---------------------------------------------------------------1-66
Figure 2-1 Fair Weather Cumulus (L1) --------------------------------------------------------------- 2-1
Figure 2-2 Towering Cumulus (TCU) (L2)-----------------------------------------------------------2-1
Figure 2-3 Stratocumulus from Cumulus (L4) ------------------------------------------------------- 2-2
Figure 2-4 Stratocumulus not from Cumulus (L5) -------------------------------------------------- 2-2
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Figure 2-5a Cumulonimbus Mammatus (L9)----------------------------------------------------------2-2
Figure 2-5b Cumulonimbus Mammatus (L9)----------------------------------------------------------2-2
Figure 2-6 Cumulonimbus (L3)------------------------------------------------------------------------2-3
Figure 2-7 Cumulonimbus (L9)------------------------------------------------------------------------2-3
Figure 2-8 Altostratus (M1) ----------------------------------------------------------------------------2-3
Figure 2-9 Nimbostratus (M2) ------------------------------------------------------------------------- 2-3
Figure 2-10 Altocumulus (M3) --------------------------------------------------------------------------2-4
Figure 2-11 Altocumulus (M5) --------------------------------------------------------------------------2-4
Figure 2-12 Altocumulus Castellanus (M8) -----------------------------------------------------------2-4
Figure 2-13 Cirrus (H1)-----------------------------------------------------------------------------------2-4
Figure 2-14 Cirrus (H4) Progressively Invading the Sky---------------------------------------------2-4
Figure 2-15 Cirrostratus (H6) with Cirrus--------------------------------------------------------------2-5
Figure 2-16 Cirrostratus (H7) Covering the Complete Sky------------------------------------------ 2-5
Figure 2-17 Cirrocumulus (H9) Alone and with Cirrus ----------------------------------------------2-5
Figure 2-18 Nephanalysis Example --------------------------------------------------------------------- 2-18
Figure 2-19 VAD Wind Profile (VWP) Product------------------------------------------------------- 2-8
Figure 2-20 Base Reflectivity Product. ----------------------------------------------------------------- 2-9
Figure 2-21 Reflectivity Cross-Section Product------------------------------------------------------- 2-9
Figure 2-22 Echo Tops Product-------------------------------------------------------------------------- 2-9
Figure 2-23 MCL Calculations -------------------------------------------------------------------------- 2-10
Figure 2-24 Parcel Method------------------------------------------------------------------------------- 2-10
Figure 2-25 RH and OVV Graph------------------------------------------------------------------------ 2-11
Figure 2-26 Dissipation of Stratus Using Mixing Ratio and Temperature ------------------------- 2-12
Figure 2-27 Tropopause Method of Forecasting Cirrus ---------------------------------------------- 2-13
Figure 2-28a CAT and Surface Cyclogenesis ----------------------------------------------------------- 2-18
Figure 2-28b CAT and Surface Cyclogenesis North of the Main Jet---------------------------------2-19
Figure 2-29a-d CAT and Upper-Level Lows ------------------------------------------------------------ 2-19
Figure 2-30 CAT and the Shear Line Associated with an Upper-Level Low ---------------------- 2-20
Figure 2-31 United Air Lines Jet Stream Turbulence Model ---------------------------------------- 2-20
Figure 2-32 CAT and Diffluent Wind Patterns -------------------------------------------------------- 2-21
Figure 2-33 CAT and Strong Winds--------------------------------------------------------------------- 2-21
Figure 2-34 Turbulence with Confluent Jets-----------------------------------------------------------2-21
Figure 2-35 Two Basic Cold–Air Advection Patterns Conducive to CAT -------------------------2-22
Figure 2-36 Common Open-Isotherm CAT ------------------------------------------------------------ 2-22
Figure 2-37 CAT in Thermal Troughs ------------------------------------------------------------------2-23
Figure 2-38 CAT in Thermal Troughs ------------------------------------------------------------------ 2-23
Figure 2-39 Closed Isotherm CAT ---------------------------------------------------------------------- 2-23
Figure 2-40 CAT and Shearing Troughs ------------------------------------------------------------------- 2-24
Figure 2-41 CAT Associated with Strong Wind Maximum to the Rear of the Upper
Trough---------------------------------------------------------------------------------------- 2-24
Figure 2-42 CAT in a Deep 500-mb Pressure Trough ------------------------------------------------ 2-24
Figure 2-43 Double Trough Configuration------------------------------------------------------------- 2-25
Figure 2-44 CAT and Upper-Air Ridges---------------------------------------------------------------- 2-26
Figure 2-45 Mountain-Wave Clouds-------------------------------------------------------------------- 2-26
Figure 2-46 Mountain-Wave Clouds-------------------------------------------------------------------- 2-27
Figure 2-47 Mountain Wave Nomogram---------------------------------------------------------------2-28
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Figure 2-48 Mountain Wave Cloud Structure---------------------------------------------------------- 2-28
Figure 2-49 Graph of Mountain Wave Turbulence Potential ---------------------------------------- 2-29
Figure 2-50a Satellite Depiction of a Gravity Wave---------------------------------------------------- 2-31
Figure 2-50b Satellite Depiction of a Gravity Wave---------------------------------------------------- 2-31
Figure 2-51 Forecasting Checklist for Low-Level Turbulence --------------------------------------2-32
Figure 2-52 Turbulence Forecasting from Skew-T --------------------------------------------------- 2-33
Figure 2-53 Low-Level Turbulence Nomogram—Temperature Gradient and
Surface Winds------------------------------------------------------------------------------- 2-34
Figure 2-54 CAT in a Deformation Zone--------------------------------------------------------------- 2-35
Figure 2-55 Example of Tansverse Waves ------------------------------------------------------------- 2-35
Figure 2-56 Example of Billow Clouds ---------------------------------------------------------------- 2-36
Figure 2-57 Example of Mountain Wave--------------------------------------------------------------- 2-36
Figure 2-58 Spectrum Width Product------------------------------------------------------------------- 2-37
Figure 2-59 Base Velocity Product ---------------------------------------------------------------------- 2-38
Figure 2-60 Vertically Integrated Liquid (VIL) Product---------------------------------------------- 2-38
Figure 2-61 Icing Type Based on Temperature -------------------------------------------------------- 2-43
Figure 2-62 Frequency of Freezing Precipitation ----------------------------------------------------- 2-45
Figure 2-63 Cumuliform Cloud Icing Locations ------------------------------------------------------2-46
Figure 2-64 Icing with a Warm Front ------------------------------------------------------------------- 2-47
Figure 2-65 Icing with a Cold Front -------------------------------------------------------------------- 2-47
Figure 2-66 Intake Icing ---------------------------------------------------------------------------------- 2-48
Figure 2-67 Carburetor Icing----------------------------------------------------------------------------- 2-48
Figure 2-68 Icing Flowchart ----------------------------------------------------------------------------- 2-51
Figure 2-69 Typical Icing Areas in a Mature Cyclone ------------------------------------------------2-51
Figure 2-70 Bright Band Identification Using the WSR-88D.------------------------------------------ 2-52
Figure 2-71 Example of Visible Satellite Picture.-----------------------------------------------------2-53
Figure 2-72 Example of a Colorized IR Satellite Picture -------------------------------------------- 2-53
Figure 2-73 Example of a Meteosat satellite over the Balkans-------------------------------------- 2-54
Figure 2-74 Example of -8D Method ------------------------------------------------------------------- 2-54
Figure 2-75 Increasing Wind Speed Pattern------------------------------------------------------------ 2-56
Figure 2-76 Decreasing Wind Speed Pattern ---------------------------------------------------------- 2-56
Figure 2-77 Example Contrails Chart------------------------------------------------------------------- 2-59
Figure 2-78 Jet Contrail Curves on a Skew-T --------------------------------------------------------- 2-61
Figure 2-79 Space Environment Global Situational Awareness Product--------------------------- 2-66
Figure 2-80 Ionospheric Conditions Impacting UHF SATCOM Chart----------------------------- 2-68
Figure 2-81 Ionospheric Conditions Impacting HF Propagation Communications and
other HF Operations Chart ---------------------------------------------------------------- 2-69
Figure 2-82 UHF SATCOM Scintillation Nowcast and Forecast Chart---------------------------- 2-70
Figure 2-83 Point-to-Point HF Radio Usable Frequency Forecast Chart -------------------------- 2-70
Figure 2-84 HF Illumination Maps Nowcast and Forecast Chart ----------------------------------- 2-71
Figure 2-85 Estimated Global Positioning Satellite (GPS) Single Frequency Error Map ------- 2-71
Figure 2-86 Short Wave Fade Event Warning Example---------------------------------------------- 2-72
Figure 2-87 Solar X-Ray Event Warning Example --------------------------------------------------- 2-73
Figure 2-88 Major Solar Flare Event Warning Example --------------------------------------------- 2-73
Figure 2-89 Geomagnetic Event Warning Example -------------------------------------------------- 2-74
Figure 2-90 Energetic Particle Event Warning Example ---------------------------------------------2-75
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Figure 2-91 Radio Event Warning Example ----------------------------------------------------------- 2-76
Figure 2-92 Example Solar Radio Burst Advisory----------------------------------------------------2-77
Figure 2-93 An Atmospheric Particle Emits Electromagnetic (EM) Energy ---------------------- 2-78
Figure 2-94 The Electromagnetic Spectrum ----------------------------------------------------------- 2-78
Figure 2-95 Reflection------------------------------------------------------------------------------------ 2-79
Figure 2-96 Visual Contrast------------------------------------------------------------------------------ 2-80
Figure 2-97 Rayleigh Scattering------------------------------------------------------------------------- 2-81
Figure 2-98 Mie Scattering------------------------------------------------------------------------------- 2-81
Figure 2-99 Geometric Scattering----------------------------------------------------------------------- 2-82
Figure 2-100 Low Clutter---------------------------------------------------------------------------------- 2-83
Figure 2-101 Medium Clutter ----------------------------------------------------------------------------- 2-84
Figure 2-102 High Clutter --------------------------------------------------------------------------------- 2-84
Figure 2-103 Apparent, Inherent, and Threshold Contrast -------------------------------------------- 2-85
Figure 2-104 Chemical Downwind Message------------------------------------------------------------ 2-89
Figure 2-105 Effective Downwind Message ------------------------------------------------------------ 2-89
Figure 2-106 Worldwide Depiction of Active Volcanoes---------------------------------------------- 2-90
Figure 3-1 Single-Cell Storm Hodograph------------------------------------------------------------- 3-1
Figure 3-2 Typical Multi-Cell Storm Hodograph---------------------------------------------------- 3-2
Figure 3-3 Supercell Hodograph----------------------------------------------------------------------- 3-2
Figure 3-4 Classic Supercell---------------------------------------------------------------------------- 3-3
Figure 3-5 Typical High-Precipitation (HP) Supercell ---------------------------------------------- 3-3
Figure 3-6 Low-Precipitation (LP) Supercell -------------------------------------------------------- 3-4
Figure 3-7a Typical Dry Microburst Atmospheric Profile ------------------------------------------- 3-4
Figure 3-7b Typical Wet Microburst Atmospheric Profile ------------------------------------------- 3-5
Figure 3-7c Typical Hybrid Microburst Atmospheric Profile --------------------------------------- 3-5
Figure 3-8 Type “A” Tornado Producing Synoptic Pattern----------------------------------------- 3-6
Figure 3-9 Type “B” Tornado Producing Synoptic Pattern ----------------------------------------- 3-8
Figure 3-10 Type “C” Tornado Producing Synoptic Pattern----------------------------------------- 3-9
Figure 3-11 Type “D”Tornado Producing Synoptic Pattern------------------------------------------ 3-10
Figure 3-12 Barotropic Low ----------------------------------------------------------------------------- 3-11
Figure 3-13 Type “E” Tornado Producing Synoptic Pattern ----------------------------------------- 3-12
Figure 3-14 Supercell Example--------------------------------------------------------------------------3-22
Figure 3-15 Line Echo Wave Pattern (LEWP)/Bow Echo Evolution------------------------------- 3-23
Figure 3-16a Bow Echo------------------------------------------------------------------------------------ 3-23
Figure 3-16b Bow Echo Reflectivity Example---------------------------------------------------------- 3-24
Figure 3-17 Sea Breeze Front on Reflectivity Product ----------------------------------------------- 3-25
Figure 3-18 T2 Gust Computation Chart--------------------------------------------------------------- 3-27
Figure 3-19 Hail Prediction Chart----------------------------------------------------------------------- 3-29
Figure 3-20 Skew-T Chart-------------------------------------------------------------------------------- 3-29
Figure 3-21 Preliminary Hail Size Nomogram -------------------------------------------------------- 3-30
Figure 3-22 Final Hail Size Nomogram ----------------------------------------------------------------3-30
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