25TH OPERATIONAL WEATHER SQUADRON

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(No Transcript)
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Instrument Refresher Course
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Overview

• Seasonal Patterns
• Climatology
• Flight Hazards
• Lightning
• Icing
• Turbulence
• METAR/TAF Code
• 25th Operational Weather Squadron Products

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• SEASONAL PATTERNS

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Seasonal Patterns
Four Corners High
Spring / Late Summer Pattern Hot and Dry Weather
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Seasonal Patterns
Mid-Latitude Storm
H
Fall, Winter, Spring Pattern Rain, Snow, Wind
Producer
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Seasonal Patterns
California Cut-Off Low
Winter-Spring Pattern Rain and Wind
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Seasonal Patterns
Monsoonal Flow
Summer Pattern Thunderstorm Producer
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Summer Weather Pattern
Winds shift from dry Westerly to moist
South-Easterly direction ? Moisture, heat,
thermal lift over mtns
Avg monsoon start 7 Jul
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The Monsoon Difference
Pre-Monsoon Hot and Dry
What a difference a wind shift makes!
Monsoon Hot, humid, and Thunderstorms
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• CLIMATOLOGY

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Average Temperatures
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Thunderstorms Days
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Average Rainfall
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• FLIGHT HAZARDS

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Flight Hazards

• All thunderstorms are hazardous to all aircraft
• Thunderstorms always imply
• Severe/Extreme Turbulence
• Severe Icing
• Low-level Wind Shear
• Lightning
• Hail

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Thunderstorms
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Thunderstorms
Cumulus Stage--Towering Cumulus
Sharply defined edges
More vertical extent than horizontal
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Thunderstorms
Mature Stage--Cumulonimbus
Distinct anvil
Rain starts to fall
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Thunderstorms
Microburst

• SHORT LIVED WIND EVENT
• VISUAL CLUES
• DUST AND DUST RINGS ON SURFACE
• RAIN SHAFTS AND CURLING RAIN
• THUNDERSTORMS

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Thunderstorms
Microburst
Dust ring on surface
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Lightning
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Lightning

• Where can you find it
• Within 8C of the freezing level
• 5,000 feet of the freezing level
• In light precipitation (including snow)
• In clouds (including debris clouds)
• In light or negligible turbulence

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Lightning

• How can you tell if a charge is building up on
  your aircraft?
• St. Elmos Fire
• Light Precipitation
• Static on your radio

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Lightning

• 2nd leading cause of direct weather deaths
• Kills more than hurricanes and tornadoes
  combined!
• Kills 100 / year
• Kills 5 of those struck
• Elusive data
• 30 - 50 under-reported

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Lightning
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Lightning Damage - U2
Aircraft induced lightning strike
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Hail

• Often found under the Anvil
• Has been encountered as high as 45,000'
  MSL
• May be carried up to 20 miles downwind
• CANNOT SEE ON RADAR, unless inside a storm

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Hail
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Hail Damage - Navy S3
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• TURBULENCE

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TURBULENCE

• JETSTREAM
• Occurs near Jetstream and Tropopause
• Worst below and on the low pressure side of jet
• SHOWERS/CONVECTIVE ACTIVITY
• MDT-SVR TURB can occur

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TURBULENCE

• THERMAL
• Associated with heating, rising air, and
  different surfaces heating at different rates
• Mostly light, occasional moderate, surface to
  10,000 feet
• Calm or light winds aid in heating
• Most prevalent in late afternoon to early evening
• Local areas of occurrence Across rough terrain
  from surface to 5,000 feet when temperatures gt 90

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TURBULENCE

• MOUNTAIN WAVE
• Most severe type of terrain induced turbulence
• Caused by stable air with strong winds crossing
  mountain barrier
• Extends up to 40,000 feet
• Occurrence of Intensities
• Severe- up to 150 miles leeward of ridge
• Moderate-as far as 300 miles leeward
• Can identify by cloud types cap, rotor,
  lenticular

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MTN WAVE TURBC CLOUDS
LENTICULAR
STRONG WINDS
CAP CLOUD
MOUNTAIN RANGE
ROTOR
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LENTICULAR CLOUD
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Mtn Wave Turbc in NV and UT--rippled clouds
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• ICING

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ICING

• RIME (Between 0 and -20 C)
• - Rough, milky, and opaque
• - Forms when super-cooled droplets freeze on
  contact with aircraft
• - Stratus clouds
• CLEAR (Most Dangerous, Between 0 and -10 C)
• - Glossy, clear layer of ice that forms after
  large super-cooled droplets spread over the
  aircraft before freezing
• - Cumulus clouds
• MIXED
• - Combination of the two--usually occurs in
  unstable clouds between (-9 and
• -15 C)
• Icing should not occur at temperatures below
  -22C

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ICING ALONG A COLD FRONT
Flight Path A Icing Threat Possible
Flight Path B Significant Icing Threat Likely
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ICING INTENSITIES

• Trace - Icing barely perceptible
• Light - Rate of accum could be hazardous after 1
  hour (Deice used)
• Moderate - Rate of accum hazardous after short
  time
• (Deice frequently used)
• Severe - Rate of accumulation is so severe
  deice/anti-ice is not effective

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• METAR TAF Codes

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METAR Code
KDMA 281959Z 34007KT 210V350 50SM FEW050 BKN080
12/M01 A2996 RMK SLP132 MTN TOPS OBSCD NE
WND DATA ESTMD METARs will always be in this
order KDMA Airfield Identifier 281959Z Date
and time of observation, 28 day of the month at
1959Z 34007KT Wind direction and speed are 340
degrees at 7 knots 210V350 Wind is varying
between 210 and 350 degrees (not reported if wind
is not varying) 50SM Prevailing visibility is
50SM FEW050 BKN080 Sky condition is Few at
5000ft and Broken at 8000ft AGL 12/M01 Temp is
12 degrees C, Dewpoint temp is -1 degree C A2996
Altimeter Setting is 29.96 RMK remarks,
these can include any information the observer
feels is operationally significant SLP132 Sea
level pressure is 1013.2mb MTN TOPS OBSCD NE
mountain tops are obscured to the NE WND DATA
ESTMD wind data is estimated
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TAF Code

• KDMA 281313 VRB06KT 9999 BKN050 BKN080 620755
  590004 QNH2990INS
• BECMG 1819 28009KT 9999 SCT050 BKN080 620804
  QNH2988INS
• BECMG 2021 28012G18KT 9999 FEW120 QNH2985INS
  WND 28010KT AFT 00
• BECMG 0405 15006KT 9999 SKC QNH2989INS
  T14/23Z T06/13Z
• First line
• 281313 date and valid time of the forecast, 28
  day of the month, valid between 1300Z and 1300Z
  the following day
• VRB06KT wind forecast
• 9999 unlimited visibility, visibility expected
  is encoded in meters in military TAFs
• BKN050 BKN080 sky condition
• 620755 icing group, light icing from 7,500 to
  12,500ft. Note, last number in the group denotes
  the THICKNESS of the layer
• 590004 turbulence group, severe turbulence from
  the surface to 4,000ft. Note, last number in the
  group denotes the THICKNESS of the layer
• QNH2990INS lowest altimeter expected between
  281300Z and 281900Z is 29.90

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TAF Code

• KDMA 281313 VRB06KT 9999 BKN050 BKN080 620755
  590004 QNH2990INS
• BECMG 1819 28009KT 9999 RA BKN050 BKN080
  620804 QNH2988INS
• BECMG 2021 28012G18KT 9999 NSW FEW120
  QNH2985INS WND 28010KT AFT 00
• BECMG 0405 15006KT 9999 SKC QNH2989INS
  T14/23Z T06/13Z
• Second line
• BECMG 1819 weather transitioning between
  281800Z and 281900Z. Expect following weather to
  be predominant after 1900Z.
• -RA present weather, in this case, light rain.
  - denotes light, denotes heavy, no descriptor,
  moderate. Other confusing present weather codes
  BR (mist), FU (smoke), PL (ice pellets), GR
  (hail). VC vicinity (between 5 and 10 miles
  away)
• Third line
• WND 28010KT AFT 00 After 290000Z, expect winds
  to change to 280 degrees at 10 knots
• NSW no significant weather
• Fourth line
• SKC skies clear of any clouds. If you see CLR,
  denotes clear skies below 12,000ft.
• T14/23Z T06/13Z expect high temp of 14 degrees
  C at 282300Z, low temp of 6 degrees C at 291300Z.
  The first to occur, high or low, will be encoded
  first.

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25th Operational Weather Squadron

• Provide 24 hour weather support in the form of
• Forecast Warnings
• Flight Hazard Forecasts
• Flight Weather Briefings
• https//ows.dm.af.mil/

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Forecast Watches Warnings
Watches Lightning w/i 5nm (lead time 30
min) Warnings Tornado (lead time 30 min) Winds
50kt (lead time 120 min) Hail 3/4" (lead
time 90 min) Surface Winds 35kt lt 50kt (lead
time 90 min) Hail 1/2" lt 3/4" (lead time 90
min) Heavy Rain ( 2" in 12 hours) (lead time
90 min) Observed Warning Lightning w/i 5nm
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Web Page Products
Icing
Turbulence
Thunderstorms
Forecasts available for 00 48 hours Via the
25th OWS website
FL Wind/Temp
VFR/IFR Conditions
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WEB PAGE https//ows.dm.af.mil/
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• QUESTIONS?