Transcript 6 AM - Dragonnorth

THERMAL SOARING
FORECASTING
Richard Kellerman
[email protected]
www.nkhome.com
THERMAL SOARING
FORECASTING
PART 1:
PART 2:
PART 3:
PART 4:
PART 5:
PART 6:
PART 7:
WHY BOTHER?
SKEWT TUTORIAL
THE CONVECTIVE BOUNDARY LAYER
A LITTLE BIT OF PHYSICS
TOOLS
MAKING THE FORECAST
RECONCILIATION
PART 1
WHY BOTHER?
WHY?
• DR JACK’S BLIPMAP FORECASTS
• FORECASTS ARE ALWAYS WRONG ANYWAY
WHO NEEDS FORECASTS ANYWAY?
PART 2
SKEWT TUTORIAL
WHAT’S THIS?
SKEWT’S
• COMPACT DATA DISPLAY (GRAPHS)
 BALLOON SOUNDINGS (T, DP, WIND)
 MODEL SOUNDINGS
• CALCULATORS
 DALR, SALR, MIXING RATIO
• IDEAL FOR THERMAL SOARING
FORECASTS
TEMPERATURE AND PRESSURE AXES
ADD DRY ADIABATS
ADD CONSTANT MIXING RATIO LINES
MAKING CLOUDS
LAPSE RATES AND ADIABATS
•
•
•
•
•
TEMPERATURE LAPSE RATE (MEASURED)
DEWPOINT LAPSE RATE (MEASURED)
DRY ADIABATIC LAPSE RATE (CALCULATED)
SATURATED ADIABATIC LAPSE RATE (CALCULATED)
IN THE CONVECTIVELY MIXED BL:
THE TEMPERATURE LAPSE RATE = DALR
TEMPERATURE AND DP ALOFT
GOOD DAY WITH CU
“CUMULUS
POTENTIAL”
GOOD DAY – NO CU
WHEN GOOD CLOUDS GO BAD, 1
WHEN GOOD CLOUDS GO BAD, 2
PART 3
THE CONVECTIVE BOUNDARY
LAYER
BOUNDARY LAYER EVOLUTION
• RUC MODEL SOUNDINGS FOR A TYPICAL GOOD
SOARING DAY IN THE LEHIGH VALLEY
• DATA IS FOR ABE JULY 3 2005 AT 6:00, 8:00, 11:00
AM AND 2:00 5:00 PM
6:00 AM
8:00 AM
9:00 AM
11:00 AM
2:00 PM
5:00 PM
COMPOSITE, MORNING
6:00 AM
8:00 AM
11:00 AM
COMPOSITE, AFTERNOON
11:00 AM
2:00 PM
5:00 PM
PART 4
SOME INTERESTING PHYSICS
GLIDER DISSIPATION
• AT 75 KTS (~40 M.S-1) MY ASW27 LOSES
ALTITUDE AT ~1 M.S-1
• IT HAS A MASS OF ABOUT 350 KG
• IN UNACCELERATED FLIGHT THAT’S A
FORCE OF ~3,400 N
• POWER = 3,400 x 1 = 3,400 W (~4.5 HP)
MAKING THERMALS
•
•
•
•
SUMMER INSOLATION IS ~ 1,000 W.M-2 @ N40º
ABOUT ½ OF THIS MAKES IT TO THE GROUND
THE GROUND GETS HOT
THE AIR GETS HOT
NUMBERS
• IT TAKES A FEW HOURS OF INSOLATION TO HEAT THE TOP
FEW CENTIMETERS OF THE GROUND BY 20Cº OR MORE
• IT TAKES JUST 2 SECONDS OF SUNLIGHT TO PROVIDE THE
ENERGY TO RAISE THE TEMPERATURE OF THE THE FIRST
1 M OF AIR BY 2Cº
• A 500 M x 500 M x 1 M SLAB OF AIR WEIGHS 250 TONS
• INSOLATION IS ON THIS SLAB IS ~1.25E8 W (THAT’S
MEGAWATTS)
• SPECIFIC HEAT OF BOTH AIR AND DRY SOILS IS
~1 x 103 J.KG
• LATENT HEAT OF WATER IS 2.27 x 106 J.KG
PART 5
TOOLS
TOOLS
•
•
•
•
•
BLIPMAPS
DALE KREMER’S BMAPPER
BILL MONINGER’S FSL JAVA SITE
RAOB 5.7
OMENS
BMAPPER
BAD OMENS
PILEUS CLOUD
SHOOTING CU
ALTOCUMULUS CASTELLANUS
GOOD OMENS
• DIURNAL TEMPERATURE SPAN >20ºF
• SURFACE (T – DP) SPREAD > 20ºF
• SURFACE WIND DIRECTION 270º - 030º (AT LEAST
IN THE EASTERN HALF OF THE COUNTRY)
PART 6
MAKING THE FORECAST:
SYNOPTICS
SURFACE ANALYSIS CHART
SA SATELLITE COMPOSITE CHART
SA RADAR COMPOSITE
SURFACE DP FIELD
SATELLITE IMAGERY
FXUS61
• “FORECAST DISCUSSION”
• ISSUED BY EVERY NWS OFFICE IN EVERY STATE
• WRITTEN BY PROFESSIONALS FOR
PROFESSIONALS BUT AVAILABLE TO ALL
• SYNOPTIC AND PROGNOSTIC ASSESSMENTS –
NOT MERELY SUMMARIES
• NUMERICAL MODEL PERFORMANCE
• ISSUED TWICE DAILY AND UPDATED WHENEVER
NEEDED, SOMETIMES FREQUENTLY
• ESSENTIAL READING
MAKING THE FORECAST
PROGNOSTICS
500 HPA CHART FORECAST
SURFACE FORECAST CHARTS
SURFACE T AND DP - ACCUWEATHER
SURFACE T AND DP, MOS
SOUNDINGS
•
•
•
•
RUC IN THE MORNING
NAM OUT TO 60 HOURS
GFS OUT TO FIVE DAYS
GFSX OUT TO 10 DAYS
ANALYZE THE SOUNDINGS
•
•
•
•
•
•
CONSTRUCT THE SURFACE DRY ADIABAT
ENTER THE BEST ESTIMATE OF SURFACE DP
DETERMINE CCL
LOOK FOR SPREADOUT
LOOK FOR VERTICAL OD
ASSESS SENSITIVITY TO CHANGES IN T, DP
SURFACE ADIABAT
PART 7
RECONCILIATION
RECONCILIATION
The process of making consistent or compatible
An act of self-mortification or devotion performed
voluntarily to show sorrow for a sin or other wrongdoing.
CLOUDBASE AND RAIN
PROBLEMS
BLIPMAP CLOUDBASE 18Z 5/20/2006
BLIPMAP CLOUDBASE 21Z 5/20/2006
MY FORECAST
RVL (MIFFLIN COUNTY AIRPORT) GLIDING FORECAST
CONTEST DAY 2
DATE
May 20 2006
MSL, FT
UCT
7:53
WINDS
STABILITY AND CLOUDS
DEG/KT DEG/KT
30,000
25,000
20,000
15,000
300/64 310/96
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
290/20
S URFACE
UTC
LOCAL
BL TOP*
CLOUDBAS E
LIFT, KTS **
S URFACE T, °F
S URFACE DP, °F
S URAFCE T, °C
S URFACE DP, °C
1500
11AM
1600
12
1700
1PM
6500
1800
2PM
1900
3PM
2000
4PM
6500
2100
5PM
2200
6PM
53
41
54
40
56
39
57
38
58
37
60
37
60
36
59
35
11.7
5.0
12.2
4.4
13.3
3.9
13.9
3.3
14.4
2.8
15.6
2.8
15.6
2.2
15.0
1.7
300/30
300/29
300/28
300/25
300/22
300/13
2300
7PM
2400
1800
2100
8PM
2PM
5PM
0
0
7000
3927 4382 5064 5518 5973 6427 6655 6655
3 -4 3 -5
4-6
3-5
305/28
300/25
300/24
300/22
295/19
295/10
MAY 17, 2005, DEWPOINT PROBLEMS
RUC 18Z SOUNDING
BL TOP
CUMULUS POTENTIAL
18Z SOUNDING WITH MODIFIED SURFACE DP
MY FORECAST
RVL (MIFFLIN COUNTY AIRPORT) GLIDING FORECAST
CONTEST DAY 3
17-May-05
DATE
UCT
MSL, FT
9:00
WINDS
STABILITY AND CLOUDS
30,000
25,000
20,000
15,000
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
SURFACE
1500
UTC
LOCAL
11AM
T °C
DP °C
T °F
DP °F
11.0
1.0
52
34
1600
12
1700
1PM
1800
2PM
1900
3PM
2000
4PM
14.0
0.5
57
33
2100
5PM
2200
6PM
2300
7PM
2400
8PM
DEG/KT
DEG/KT
276/51
268/48
320/06
~0
~0
~0
~0
~0
307/06
~0
~0
~0
~0
~0
1800
2PM
2100
5PM
16.0
0.5
61
33
BL TOP
FREEZING LVL
FEW
SCT
SPREADOUT
TOWERING
CIRRUS
CLOUDS
LIFT
CAUTIONS
CONFIDENCE
6-Apr
NONE
REASONABLE
THE BIG PICTURE
High pressure now firmly in place with accompanying subsidence inversion. Winds very light. RUC Rapid Update Cycle)
continues to be the moisture maverick. It is wildly drier than GFS (Global Forecast System) , NAM (North American
Mesoscale Model) or NGM (Nested Grid Model). Expect good thermal soaring tomorrow.
CONCLUSIONS
• DON’T TAKE FORECASTS FOR GRANTED
– LOOK UNDER THE HOOD
• DATA RULES, NOT MODELS
– MAKE USE OF THE RELTIME DISSEMINATION
OF DATA
• FLY MORE OFTEN
– IT’S USUALLY BETTER THAN FORECAST