THERMAL SOARING FORECASTING Richard Kellerman rkellermannkhome com www

THERMAL SOARING FORECASTING Richard Kellerman rkellerman@nkhome. com 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 ASW 27 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 @ N 40º ABOUT ½ OF THIS MAKES IT TO 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 20 Cº OR MORE • IT TAKES JUST 2 SECONDS OF SUNLIGHT TO PROVIDE THE ENERGY TO RAISE THE TEMPERATURE OF THE FIRST 1 M OF AIR BY 2 Cº • A 500 M x 1 M SLAB OF AIR WEIGHS 250 TONS • INSOLATION IS ON THIS SLAB IS ~1. 25 E 8 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

FXUS 61 • “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 18 Z 5/20/2006

BLIPMAP CLOUDBASE 21 Z 5/20/2006

MY FORECAST

MAY 17, 2005, DEWPOINT PROBLEMS

RUC 18 Z SOUNDING

BL TOP

CUMULUS POTENTIAL

18 Z SOUNDING WITH MODIFIED SURFACE DP

MY FORECAST

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