CHAPTER 5

CHAPTER 27
Section 27.2 Winds and Temperatures Aloft

WIND AND TEMP ALOFT
Based on the North American Mesoscale (NAM) model
Altitudes in msl:
3000
6000
9000
12000
18000
24000
30000
39000
Temps above 24,000 feet are negative
They come out 4 times a day every 6 hours
Good for the time on the chart

WIND AND TEMP ALOFT
Winds not issued for stations within 1,500
GEG’s elevation is 2,376
Since it is 624 feet from the 3,000 foot level no forecast is issued
Temps not issued for stations within 2,500 feet
YKM’s elevation is 1,099
Since it is 1,901 feet from the 3,000 foot level no temp is issued

******** FD Winds Aloft Forecast ******** DATA BASED ON 140000Z
VALID 141200Z FOR USE 0900-1800Z. TEMPS NEG ABV 24000
FT 3000 6000 9000 12000 18000 24000 30000 34000 39000
GEG 3332-06 3130-13 3046-19 3079-26 8129-31 827141 826952 813157
YKM 3112 3131-03 3142-07 3151-12 3191-18 8108-25 812740 823751 823363
LWS 2922 2932-04 3138-12 2952-17 3094-24 8027-31 826941 827452 813858

WIND AND TEMP ALOFT
Winds are true and in knots
9900 codes calm winds
100 to 199 kts is coded by subtracting 100 from the speed and adding 50 to the direction
To decode subtract 50 and add a 100

WIND AND TEMP ALOFT
******** FD Winds Aloft Forecast ******** DATA BASED ON 140000Z
VALID 141200Z FOR USE 0900-1800Z. TEMPS NEG ABV 24000
FT 3000 6000 9000 12000 18000 24000 30000 34000 39000
GEG 3332-06 3130-13 3046-19 3079-26 8129-31 827141 826952 813157
YKM 3112 3131-03 3142-07 3151-12 3191-18 8108-25 812740 823751 823363
LWS 2922 2932-04 3138-12 2952-17 3094-24 8027-31 826941 827452 813858
82 – 50 = 320
71 + 100 = 171
Temp is -41

WIND AND TEMP ALOFT
******** FD Winds Aloft Forecast ******** DATA BASED ON 140000Z
VALID 141200Z FOR USE 0900-1800Z. TEMPS NEG ABV 24000
FT 3000 6000 9000 12000 18000 24000 30000 34000 39000
GEG 3332-06 3130-13 3046-19 3079-26 8129-31 827141 826952 813157
YKM 3112 3131-03 3142-07 3151-12 3191-18 8108-25 812740 823751 823363
LWS 9900 2932-04 3138-12 2952-17 3094-24 8027-31 826941 827452 813858
81 – 50 = 310
08 + 100 = 108
Temp -25
LWS at 3000 is light and variable

Graphical Winds and Temps

Chapter 27
SECTION 27.3 TERMINAL AERODROME FORECAST

TAF
Issued 4 times a day:
0000z
0600z
1200z
1800z
Good for 24 hours
Some are good for 30 hours
Covers an area out to 5sm
May be AMD or COR

TAF
1. Type
2. Location
3. Date / Time
4. Valid period
5. Wind Group
6. Visibility Group
7. Sig Wx Group

8. Vicinity
9. Clouds and VV
10.LLWAS
11. Non Convective LLWS
12. Forecast Change Group

TAF
TAF KMWH 301135Z 3012/3112 33006KT P6SM SCT150
TEMPO 3012/3014 BKN150
FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR
FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM – SHSN OVC005
3 types: TAF, TAF AMD, & TAF COR

TAF
TAF KMWH 301135Z 3012/3112 13012KT WS020/27055KT P6SM SCT150
TEMPO 3012/3014 BKN150
FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM BR
FM310500 22013G25KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005
Non convective wind shear is forecast from the surface to 2000 AGL surface winds 130@12 winds at 2000 are 270@55
Variable wind at 3 kts
G=gusts with 10 kts or more between peaks and lulls 220@13 Gusting 17

TAF
TAF KMWH 301135Z 3012/3112 33006KT P6SM SCT150
TEMPO 3012/3014 BKN150
FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM VCFG
FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005
Significant wx is given when vis is 6 or less, like Mist or light Snow Showers. If VC is used then it covers an area from 5-10sm

TAF
TAF KMWH 301135Z 3012/3112 33006KT P6SM SKC TEMPO 3012/3014 BKN150
FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM VCFG
FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005

SKC = 0 oktas sky clear
FEW = 0 to 2 oktas
SCT = 3 to 4 oktas
BKN = 5 to 7 oktas
OVC = 8 oktas

TAF
TAF KMWH 301135Z 3012/3112 33006KT P6SM 1/2SM TSRA OVC010CB
TEMPO 3012/3014 BKN150
FM302000 VRB03KT P6SM SCT060 OVC120 TEMPO 3021/3101 5SM VCFG
FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005
CB is the only cloud type in the TAF

TAF
TAF KMWH 301135Z 3012/3112 33006KT P6SM SCT150
TEMPO 3012/3014 BKN150
FM302000 VRB03KT P6SM SCT060 OVC120
TEMPO 3021/3001 5SM BR
FM310500 22013G17KT 3SM BR OVC080 PROB30 3105/3109 1SM -SHSN OVC005
TEMPO = Temporary fluctuations (greater than 50% chance) of 1hr or less. On the 30th day from 2100Z to 0100Z, 5SM in Mist is predicted. Wind, visibility and clouds are unchanged.

TAF
TAF writer guys use the METAR obs to generate these puppies
If the METAR is missing they can use other sources to generate one
AMD NOT SKED (amendments not scheduled) at the end of the TAF indicates they had to use other sources
Expanded statements use AFT 120200 and then TIL to show resumption
If the wx source is part time then AMD NOT SKED 3005-3018Z=
If the wx source requires part time augmentation then AMD LTD TO CLD VIS AND WIND 1505-1518=
For non-augmented automated sites then AMD NOT SKED
The only cloud type forecasted in a TAF is CB

TAF
Issuance

Chapter 27
Section 27.4 Aviation Surface Forecast and Aviation Clouds Forecast

This section depended on the GFA tool which has changed form with the new Aviationweather.gov site

Chapter 27
Section 27.7 World Area Forecast System

World Area Forecast System

Global forecasts of:
Upper wind and temperature (i.e., wind and temperature aloft, which is also issued in chart form for select areas);
Upper-air humidity;
Geopotential altitude of flight levels;
Flight level and temperature of tropopause (i.e., tropopause forecast);
Direction, speed, and flight level of maximum wind;
Cumulonimbus clouds;
Icing; and
Turbulence.
Global forecasts of Significant Weather (SIGWX), i.e., High-Level Significant Weather (SIGWX) forecasts (see paragraph 5.17.3).
Select regional areas of Medium-Level Significant Weather (SIGWX) forecasts

Chapter 27
27.7.1.2 WAFS Wind and Temperature
27.7.1.3 Humidity, Max Wind, Tropopause Forecasts
27.7.1.4 WAFS Turbulence, Icing and Cumulonimbus Cloud Forecast

WAFS Wind and Temps
Used by ICAO
Grid point format

WAFS Potpourri
Humidity, Max Wind, Tropopause Forecast
Grid point for flight planning systems
Turbulence, Icing and Cumulonimbus Cloud Forecast
Check it out at https://www.aviationweather.gov/wafs

Chapter 27
Section 27.8 Significant Weather Charts

LOW LEVEL SIG WX PROG (SIGWX)
Used for wx briefings
Covers CONUS 24,000 and below
12hr and 24 hr panels
This is a prognostic (Prog) chart
Snapshot of the weather in the future

LOW LEVEL SIG WX PROG
Flying Categories
IFR outlined with solid red
Marginal VFR outlined with a scalloped blue
Everything else is VFR

LOW LEVEL SIG WX PROG
Turbulence
Brown dashed line
1 witch hat mod turb
2 witch hats sev turb
3 witch hats extreme turb
Tops and bases separated by a /
Absence of lower number indicates to the surface

LOW LEVEL SIG WX PROG
Freezing level at surface blue zigzag
Freezing level aloft green dashed line
Spaced at 4,000 foot intervals
Usually everything north of the zigzag is below freezing
Lines are drawn for the highest freezing level if multiple layers exist
Multiple layers may be drawn see example at right

LOW LEVEL SIG WX PROG
Issuance
Comes out 4 times a day
2 charts 12 and 24hrs

Chapter 27
Section 27.8.2 Mid-Level Significant Weather Chart

MID LEVEL SIG WX
Covers altitude from 10,000msl to FL450
Issuance
24hr forecast issued 4 times a day

MID LEVEL SIG WX
Coverage of CBs are indicated by a box appended to area enclosed by a red scalloped line
xxx means bases are below the lower limit of the chart
ISOL – less than 4/8ths coverage
OCNL – 4/8ths to 6/8ths
FRQ – more than 6/8ths
EMBD – used when thunderstorms are embeded

MID LEVEL SIG WX
Tropopause heights indicate the level of the tropopause
The L is for low pressure
The H is for High pressure
Tropical storms and hurricanes are also on this puppy
Moderate or severe icing is enclosed by the red scalloped lines
Moderate or severe turbulence may also be indicated by yellow dashed line
Non cumulus cloud coverage indicated using standard oktas scale
Volcanic eruptions and my personal favorite radioactive materials release

MID LEVEL SIG WX
Fronts have an arrow showing speed of movement
Jet streams are green
Standard wind pennants indicate core speed
Altitude separated by a / indicate top and bottom of 80kt jet field
Double hash marks indicate change in speed in 20kt intervals

Chapter 27
Section 27.8.3 High-Level Significant Weather Chart

HIGH LEVEL SIG WX
Covers altitudes from FL250 to FL630
U2 and SR71 pilots use these
Pretty much the same symbology is used here with a few additions
Oh look there’s a volcano in Guatemala

HIGH LEVEL SIG WX
Smokes on a daily basis but last eruption was 2/8/15
Also known as the volcano of fire, De Fuego is about 10,000 feet high
Is one of the most active volcanoes in the Americas
Has erupted on a regular basis since 1524

HIGH LEVEL SIG WX
Like the mid level sig wx these are mostly for international flights
Used by airline dispatchers
Issuance

Chapter 27
Section 27.9 Short-Range Surface Prognostic Chart

SHORT RANGE SURFACE PROG
Shows:
Surface pressure systems, fronts, isobars and precip
Good out to 2.5 days
4 forecast periods 12, 18, 24, 48 and 60 hours

SHORT RANGE SURFACE PROG
Precipitation symbology
Rain (Chance)–(light green)–There is a 25 to less than 55 percent probability of measurable rain (≥0.01”) at the valid time.
Rain (Likely)–(dark green)–There is a greater than or equal to 55 percent probability for measurable rain (≥0.01”) at the valid time.
Snow (Chance)–(light blue)–There is a 25 to less than 55 percent probability of measurable snowfall (≥0.01” liquid equivalent) at the valid time.
Snow (likely)–(dark blue)–There is a greater than or equal to 55 percent probability of measurable snow (≥0.01” liquid equivalent) at the valid time.
Mix (Chance)–(light purple)–There is a 25 to less than 55 percent probability of measurable mixed precipitation (≥0.01” liquid equivalent) at the valid time. “Mixed” can refer to precipitation where a combination of rain and snow, rain and sleet, or snow and sleet are forecast.

SHORT RANGE SURFACE PROG

Mix (Likely)–(dark purple)–There is a greater than or equal to 55 percent probability of measurable mixed precipitation (≥0.01” liquid equivalent) at the valid time. “Mixed” can refer to precipitation where a combination of rain and snow, rain and sleet, or snow and sleet are forecast.
Ice (Chance)–(light brown)–There is a 25 to less than 55 percent probability of measurable freezing rain (≥0.01”) at the valid time.
Ice (Likely)–(brown)–There is a greater than or equal to 55 percent probability of measurable freezing rain (≥0.01”) at the valid time.
T-Storm (Chance)–(red hatching)–There is a 25 to less than 55 percent probability of thunderstorms at the valid time. Areas are displayed with diagonal red hatching enclosed in red border.
T-Storm (Likely and/or Severe)–(dark red)–There is a greater than or equal to 55 percent probability of thunderstorms and/or the potential exists for some storms to reach severe levels at the valid time.

SHORT RANGE SURFACE PROG
Uses the standard symbology for pressure systems and fronts
Pressure systems are depicted by pressure centers, troughs, isobars, drylines, tropical waves, tropical storms, and hurricanes using standard symbols
Isobars are denoted by solid thin black lines and labeled with the appropriate pressure in millibars.
The central pressure is plotted near the respective pressure center
Good for seeing the progression over 60 hrs

SHORT RANGE SURFACE PROG
Issuance
These are mainly good for seeing the progression over a 2.5 day period

https://aviationweather.gov/graphics/

click the WPC prog chart tab

Chapter 27
Section 27.10 Upper Air Forecasts

Upper Air Forecasts
Upper air forecasts are generated using computer models so complex they are run on the NWS Cray super computer
These are intended to be used for guidance for Meteorologists
You may find more information on the NCEP Central Operations Model Analyses and Guidance Web Site

Chapter 27
27.10.1 Constant Pressure Levels Forecasts

Constant Pressure Levels Forecast
Computer modeled forecast for a specified pressure level
Handy for forming a 3D picture of the weather
Shading indicates winds greater than 70kts
Issuance
The Global Forecast System(GFS) model and the North American Model (NAM) come out 4 times a day
The High Resolution Rapid Refresh (HRRR) comes out hourly

Constant Pressure Levels Forecast
Most of these provide a winds forecast
They may also show
Temperature
Relative Humidity
Vorticity
Other derived parameters
Used to provide an overview of weather patterns
The Jet Stream shows up on the 300mb, 250mb and 200mb levels

Constant Pressure Levels Forecast
Where does the info come from?
Radiosonde observations
Wx reconnaissance aircraft
Radiosonde observations (see Figure 5-30)
Weather reconnaissance aircraft observations
Aircraft observations on-time and on-level
Aircraft observations off-time or off-level
Satellite wind estimates
Other data sources are used as well but not plotted

Constant Pressure Levels Forecast
5 separate charts
850mb 5,000
700mb 10,000
500mb 18,000
300mb 30,000
200mb 39,000

CONSTANT PRESSURE ANALYSIS CHART
850mb about 5,000 feet

700MB CHART
The humidity contours are 50% relative humidity (line), 70% relative humidity (light green shading), and 90% relative humidity (dark green shading).
However, remember this is only at the 700 mb level. There may be more (or less) moisture at other levels.
Omega (Ω) represents vertical motion.
The sign on Omega is relative to the earth’s surface. Motion away from the surface (rising air) is given minus the (-) sign (red color).
Motion toward the surface (sinking air) is not given a sign and is therefore positive (+) (blue color)
Black numbers are height in meters so 310 is 3100 meters

CONSTANT PRESSURE ANALYSIS CHART

Constant Pressure Levels Forecast
A Virgin Atlantic plane appears to have set a brand new speed record for a Boeing 787 Dreamliner after it was clocked reaching a very impressive 801mph over the US.
The flight from Los Angeles International to London’s Heathrow hit the top ground speed on 2/18/19 while flying at 35,000 feet over Pennsylvania.
It was pushed on its 5,449 mile journey by an extra strong jet stream that at times reached over 200mph over the eastern US states.
However, the huge speed didn’t last for long. When the plane started flying over the Atlantic, it dropped to around 710mph, according to FlightAware.
But it did mean that the flight landed at Heathrow’s Terminal 3 at 8:22am on Tuesday – 48 minutes ahead of schedule. The gate-to-gate flight time was nine hours, 34 minutes, and wheels up to touchdown took just nine hours, 13 minutes.
The usual cruising speed for a Boeing 787 Dreamliner is 561mph.

Constant Pressure Levels Forecast
British Airways 747 Flight 112—which left John F. Kennedy International Airport at 6:47 p.m. on 2/8/20 and arrived at Heathrow Airport at 4:43 a.m. on Sunday—completed the trip in just 4 hours and 56 minutes, 80 minutes ahead of schedule. That’s more than an hour faster than the six hours and 13 minute average flight time.
The Boeing 747, which reached a top speed of 825 mph, easily broke a record that had previously been held by Norwegian Air. One of the Scandinavian airline’s jets completed the same route in five hours and 13 minutes in January 2018. Two Virgin Atlantic traveling the same route also bested the old record on Saturday night.
Flight 112’s record-setting time came can largely be credited to Storm Ciara. The flight was able to take advantage of the strongest part of the jet stream which created tailwinds of more than 200 mph, reports the Times. While the speed of sound is 767 mph, BA’s flight time is considered subsonic because of those winds.

Constant Pressure Levels Forecast
Here are the Constant Pressure charts for 2/18 and 2/19

Constant Pressure Levels Forecast
USEFUL:
Can determine areas of high winds
Gives the upper air wx picture
Can determine possible levels of icing
Can determine the right altitude for best wind in combination with the best wx
Look for the high and low pressure systems of associated wx
Constant Pressure Levels Forecast
Lets take a look at a current one:
https://www.spc.noaa.gov/obswx/maps/

Chapter 27
27.11 Freezing Level Forecast Graphics

Freezing Level Forecast Graphics
Based on NWS computer models
Supplemental to the icing AIRMETs
Updated hourly
Hatched or spotted regions represent inversions with more than one freezing level
https://aviationweather.gov/gfa/#temps

Chapter 27
27.12 Forecast Icing Product

This was covered earlier in chapter 25.5
It can be found at aviationweather.gov under:
Tools –> Decision Support Imagery –> Icing

Chapter 27
27.13 Graphical Turbulence Guidance (GTG)

This was covered earlier in chapter 25.6
It can be found at aviationweather.gov under:
Tools –> Decision Support Imagery –> Turbulence

Chapter 27
27.14 Cloud Tops
This product is transmitted through FIS-B and is displayed on an ADS-B linked screen in the cockpit
In addition cloud top information can be found:
https://aviationweather.gov/gfa/#clouds

Chapter 27
Section 27.15 Localized Aviation Model Output Statistics (MOS)

Localized Aviation Model Output Statistics(MOS)
The MOS is a forecast that uses statistical models
Both in graphical and text format
Generated for 1500 different locations
Entirely automated so may not be as accurate as a human
These are available on the web and through some flight bag programs
https://www.nws.noaa.gov/mdl/synop/products.php.withngm

Chapter 27
Section 27.16.1 Convective Outlooks

CONVECTIVE OUTLOOKS
Known as AC
Covers severe and non-severe convective activity
Tornadoes, winds 50kts or greater, hail 1 inch or greater
5 levels of threat:
Marginal risk (MRGL)
Slight risk (SLGT)
Enhanced risk (ENH)
Moderate risk (MDT)
High risk (HIGH)

CONVECTIVE OUTLOOKS
Issued for a 24 hr period
These are very general in nature
Days 1-3 depict general T-storm risk
The day 1, day 2 and day 3 use descriptive text to indicate the convective activity
Days 4-8 depict two probabilistic thresholds

CONVECTIVE OUTLOOKS
The area affected is read to the right of the arrow

TRAFFIC FLOW MANAGEMENT CONVECTIVE FORECAST
Section 27.16.2 Traffic Flow Management (TFM) Convective Forecast (TCF)
Graphical representation of forecast convective activity
ATC uses this thing to plan for delays and reroutes
Computer/human generated every 2 hrs
Issued year round
Not used for pilot wx briefings
Uses polygons
What the hell are polygons?
Polygons are a multi sided figure
A pentagon is a polygon with 5 sides
A nonagon is a 9 sided polygon
A decagon is a 10 sided polygon
A icosagon is a 20 sided polygon
A chiliagon is a 1,000 sided polygon
I’d like to see them draw one of these

EXTENDED CONVECTIVE FORECAST PRODUCT (ECFP)
This is the Collaborative Convective Forecast extended out to 72 hours (3days)
Intended to enhance the CCFP which is good out to only 8 hours
Same format as the CCFP
Used by ATC and airline dispatchers

Chapter 27
Section 27.16.4 Watch Notification Messages

Watch Notification Messages
The Storm Prediction Center (SPC) issues three watches:
Aviation Watch Notification Messages (SAW)
Public Severe Thunderstorm Watch Notification Message
Public Tornado Watch Notification Message
http://www.spc.noaa.gov/
Watch
Severe weather is possible
Warning
Severe weather has been observed or is expected within the hour

Aviation Watch Notification (SAW)
Includes
Severe thunderstorm threats
Tornadoes
Hail
Convective damaging winds

Aviation Watch Notification (SAW)
Issuance
These are nonscheduled
Only are issued when there is a need
Good for the time on the chart

Public Severe Thunderstorm Watch
Includes
Hail 1 inch or greater
Winds of 50kts or greater
Must impact at least 8,000 square miles for 2 hours or more
3 blocks of information
Geographical location
Valid time
Description of the threats
Issued
When 6 or more hail events are forecasted
Can be issued for smaller areas if SPC determines a need

Public Tornado Watch Notification
Issued when
2 or more tornadoes or any F2 tornado is possible
Must include the 8,000 square mile threshold for 2 or more hours
Can be issued for smaller areas if SPC determines a need
Includes
Area description
Expiration time
Largest hail size
Strongest wind gusts expected
Definition of the watch
Call to action statement
List of other valid watches
Meteorological discussion
Technical information for the aviation community

Public Tornado Watch Notification
3 blocks of information
Geographical location
Valid time
Description of the threats

Chapter 27
Section 27.18 Aviation Forecast Discussion

Aviation Forecast Discussion
Weather conditions as related to the TAF
Provides further details as to the reasoning behind the TAF
Issuance
Roughly every 6 hours
Plain language
There are 2:
AWC https://aviationweather.gov/gfa/#afd
NWS https://forecast.weather.gov/product.php?site=OTX&issuedby=OTX&product=AFD&format=CI&version=1&glossary=1

CHAPTER 27
27.19 Meteorological Impact Statement
METEOROLOGICAL IMPACT STATEMENT (MIS)
Unscheduled planning forecast tool for ARTCC
Helps ATC with flow control when the wx may impact flight ops
Good for up to 48hrs
Content includes any event that might effect the traffic flow
Includes the cause, area, altitudes and movement

MIS
Page Loaded (UTC): Sunday, 28-Feb-2010 02:01:14 GMT
Minneapolis ARTCC (KZMP) Center Weather Advisory (CWA) No Current CWAs Meteorological Impact Statement (MIS)
ZMP MIS 02 VALID 280130-281200…FOR ATC PLANNING PURPOSES ONLY…ZMP AREA WITHIN A LN FM 45N MOT-PIR-50WSW PIR…LIFR CONDS WITH CIG/VIS AS LOW AS 004 AND 1/4SM IN FG/BR. ZMP AREA E OF A LN FM 40SE YQT-35N DLL…LGT TO MOD ICG BLO 120.
If you look at the metars for this area you can see why they wanted one

Soaring Forecast
The soaring forecast is out there, somewhere

Balloon Forecast
Probably right next to the Soaring Forecast

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