Hurricane Hazard Depiction for Hurricane Hazard Depiction for Standardized Air Force Standardized Air Force

Weather Forecast ChartsWeather Forecast Charts

Capt Kevin LaCroixCapt Kevin LaCroix

1LT Christopher Wireman1LT Christopher Wireman

2828thth Operational Weather Squadron Operational Weather Squadron

• 28th Operational Weather Squadron SE CONUS mission

• Hurricane Hazards– Turbulence– Icing– Lightning/Thunderstorms

Overview

TAF LocationsTAF Locations

Advisory/Warning LocationsAdvisory/Warning Locations

Weather

support to 90

units at 70+

locations (AF,

Army, Guard,

and Reserve)

22 TAF sites Flight weather

briefings 1500+ aircraft

supported Flight hazards

graphics Tropical

Cyclone Threat

Assessment

SE CONUS OperationsSE CONUS Operations

• Air Force Weather Technical Library (AFWTL) located in Asheville, NC houses nearly 250,000 volumes; serves the information needs of meteorologists, climatologists, space scientists, computer scientists and experts in all other disciplines of interest to military meteorology.

• Holdings include foreign language documents, that they translate if needed.

• Requested they search all holdings for Tropical storms, turbulence, icing and severe weather.

• 88 documents were found in this search including several not held by the AFWTL.

• All references were either peer-reviewed, or major meteorological publications by AMS, Royal Met. Soc. etc.

Air Force Weather ResearchAir Force Weather Research

Storm Motion

Hurricane Horizontal StructureHurricane Horizontal Structure

Eye -> 5-30km Diameter

Eyewall -> 5-40km

Inner Rainbands -> Eyewall - 100km

Outer Rainbands -> ~150km - 300km

Right Front Quadrant

Right Rear Quadrant

Left Front Quadrant

Left Rear Quadrant

Eye/EyewallOuter Rainbands

Outer Rainbands

18 km

16 km

Hurricane Vertical StructureHurricane Vertical Structure

Radius of Eyewall is ~10-Radius of Eyewall is ~10-15km wider at top than at the 15km wider at top than at the

surfacesurface

Eyewall Updrafts Eyewall Updrafts < 8 m/s< 8 m/s

Outer rainband Outer rainband Updrafts < 10 m/sUpdrafts < 10 m/s

UpdraftsUpdrafts

Dry, warm Dry, warm subsiding subsiding airair

Outer rainbands can sometimes include Outer rainbands can sometimes include thunderstorms with high CB’s called “Hot thunderstorms with high CB’s called “Hot Towers” these reach more than 10 miles Towers” these reach more than 10 miles high, and result in very heavy precipitationhigh, and result in very heavy precipitation

Hurricane TurbulenceHurricane Turbulence

LightLight

ModerateModerate

SevereSevere

ExtremeExtreme

SFCSFC

500500

CONTCONT

Percent Percent EncounterEncounter

99.4%99.4%

0.5%0.5%

0.0015%0.0015%

0.0000033%0.0000033%

Only Only encounter encounter severe or severe or extreme extreme turbulence turbulence in lowest in lowest 1km of 1km of eyewalleyewall

Moderate Moderate Turbulence Turbulence only in the only in the strongest strongest convectionconvection

Turbulence Turbulence not not prevalent prevalent because of because of lack of lack of shear, both shear, both horizontal horizontal and verticaland vertical

Hurricane Turbulence Cont.Hurricane Turbulence Cont.

Distance from Storm CenterDistance from Storm Center

00 1010 2525 100100 30030010102020

Sea Sea LevelLevel

MMbb LLeevveell

200200

400400

500500

850850

975975

Cross Cross section section locationlocation

Area of Area of ShearShear

Vertical Cross Section of HurricaneVertical Cross Section of Hurricane

Eye/EyewallOuter Rainbands *

Outer Rainbands

0˚

- 4˚

Hurricane IcingHurricane Icing

Supercooled Supercooled Droplets only in Droplets only in

strongest updraftsstrongest updrafts

-10˚Area of possible

Icing 160160

200200

> FL 130> FL 130

UpdraftsUpdrafts

ClearClear

MixedMixed

- 40˚

-15˚

Icing mostly clear due to large drop size and Icing mostly clear due to large drop size and lack of supercooled droplets. Weak updrafts lack of supercooled droplets. Weak updrafts also limit icing. Severe Clear icing in eyewall, also limit icing. Severe Clear icing in eyewall, typically well above research aircraft typically well above research aircraft penetration level.penetration level.

* Different Vertical Scale* Different Vertical Scale

Average Average Freezing levelFreezing level

Hurricane Icing ForecastHurricane Icing Forecast

160160

200200

Severe ClearSevere Clear

Severe MixedSevere Mixed

200200

500500

Icing in Icing in hurricanes is all hurricanes is all inside inside thunderstorms. thunderstorms. How it could be How it could be depicted is depicted is shown here. shown here. Temperature Temperature guidance for guidance for more accurate more accurate height height representation is representation is given on given on previous page.previous page.

Icing Potential AreaIcing Potential Area

Hurricane LightningHurricane Lightning

• Eyewall Flash Eyewall Flash Rate: < 60 flashes Rate: < 60 flashes per 100 sq km/dayper 100 sq km/day

• Inner Rainband: Inner Rainband: < 20 flashes per < 20 flashes per 100 sq km/day100 sq km/day

• Outer Rainband: Outer Rainband: > 300 flashes per > 300 flashes per 100 sq km/day100 sq km/day

• Typical Typical Thunderstorm: > Thunderstorm: > 36,000 flashes per 36,000 flashes per 100 sq km/day100 sq km/day

• Equates to 4-6 Equates to 4-6 times more chance times more chance for lightning in for lightning in outerband than outerband than eyewalleyewall

Greatest Flash Greatest Flash Density in Density in Right Front Right Front QuadrantQuadrant

Hurricane Hurricane Flashes: ~ 4400 Flashes: ~ 4400

per dayper day

Storm Motion

Hurricane Thunderstorm ForecastHurricane Thunderstorm Forecast

Thunderstorm Thunderstorm Coverage for Coverage for FITL ChartFITL Chart

520520

350350

550550

FEWFEW

ISOLDISOLD

600600

SCTSCT

NSWNSW

NMRSNMRS

Max TopsMax Tops

CoverageCoverage

600600

NMRSNMRS

Aviation Hazards on ButtonsAviation Hazards on Buttons

Tropical Cyclone Forecast Tropical Cyclone Forecast RepresentationRepresentation

•OWS worldwide have standardized map backgrounds, colors, and symbology so that a forecaster will be familiar with any products on a OWS webpage no matter what theater they are in, or what OWS they are at

• Following slides show designated process for depicting Tropical Cyclones on OWS Charts

• Process uses 150-300km radius from storm center as area of major outer ring convection.

• Limitations to depicting features:

• Forecaster experience – want same “rules” for drawing storms to be worldwide

• Map Scale – eyewall process to small to accurately draw on our scale

• Technical limitations to graphics program at OWS, Leading Environmental Analysis and Display System (LEADS)

Low Level TurbulenceLow Level Turbulence

IcingIcing

ThunderstormsThunderstorms

Contact Information:

Capt Kevin LaCroix28th Operational Weather Sq.

905 Patrol Rd.

Shaw AFB, SC 29152

(803)895-0654

Kevin.lacroix@shaw.af.mil

Questions?