How meteorologists analyze hurricane data

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EAST PROVIDENCE, R.I. (WPRI) — Pilots and meteorologists on board Hurricane Hunter planes gather a tremendous amount of data in and around hurricanes.

Much of the information comes from dropsondes, instrument packs dropped into the storm. That information is sent up to a satellite and back to the National Weather Service computers where National Hurricane Center forecasters can determine the intensity and strength of storms.

A NOAA Meteorologist preparing a dropsonde.

The data is also put into computer models which aid forecasters in making hurricane forecasts.

Due to the incredible amount of information transmitted from the planes to the NHC, the data is coded.

DROPSONDE DATA

Here’s some dropsonde data from Hurricane Sandy in 2012 as it was working up the East Coast. You may remember Sandy hit New Jersey badly and Rhode Island took an indirect hit from the late October storm.

There’s a lot of numbers and letters that only a trained eye can decipher. Here’s what all the above information means:

Date: 22Z (6PM EDT) on the 28th day of the month

Part A…
Coordinates: 32.4N 76.0W

Surface and Standard Isobaric Surfaces

Level

Geo. Height

Air Temp.

Dew Point

Wind Direction

Wind Speed

1000mb

-71m (-233 ft)

This level does not exist in this area of the storm above the surface level.

992mb (29.30 inHg)

Surface (Sea Level)

20.2°C

17.5°C

315° (from the NW)

43 knots (49 mph)

925mb

598m (1,962 ft)

15.0°C

14.4°C

315° (from the NW)

51 knots (59 mph)

850mb

1,311m (4,301 ft)

13.2°C

10.7°C

340° (from the NNW)

55 knots (63 mph)

700mb

2,933m (9,623 ft)

7.6°C

About -7°C

305° (from the NW)

54 knots (62 mph)

500mb

5,630m (18,471 ft)

-8.9°C

About -58°C

290° (from the WNW)

58 knots (67 mph)

400mb

7,320m (24,016 ft)

-18.5°C

-22.9°C

280° (from the W)

24 knots (28 mph)

Type of Data Collection:  This is an Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)
Transmitted: 28th day of the month at 22:50Z
Agency: United States Air Force
Aircraft:  WC-130J Hercules with reg. number AF98-5308
Storm Number: 18
Storm Name: Sandy (flight in the North Atlantic basin)
Mission Number: 22
Observation Number: 03

Part B: Data for Significant Levels…

Significant Temperature And Relative Humidity Levels

Level

Air Temperature

Dew Point

992mb (Surface)

20.2°C (68.4°F)

17.5°C (64°F)

920mb

14.6°C (58.3°F)

14.1°C (57°F)

863mb

12.2°C (54.0°F)

11.6°C (53°F)

850mb

13.2°C (55.8°F)

10.7°C (51°F)

834mb

14.6°C (58.3°F)

About 7°C (45°F)

790mb

11.4°C (52.5°F)

About 5°C (41°F)

777mb

11.8°C (53.2°F)

About 3°C (37°F)

727mb

8.6°C (47.5°F)

About 2°C (36°F)

709mb

8.0°C (46.4°F)

About -2°C (28°F)

685mb

7.6°C (45.7°F)

About -30°C (-22°F)

650mb

5.8°C (42.4°F)

About -37°C (-35°F)

578mb

-0.3°C (31.5°F)

About -49°C (-56°F)

507mb

-8.5°C (16.7°F)

About -58°C (-72°F)

464mb

-11.3°C (11.7°F)

About -58°C (-72°F)

422mb

-17.1°C (1.2°F)

About -31°C (-24°F)

416mb

-17.3°C (0.9°F)

About -22°C (-8°F)

391mb

-18.5°C (-1.3°F)

-18.5°C (-1°F)

376mb

-21.5°C (-6.7°F)

-21.5°C (-7°F)

Significant Wind Levels

Level

Wind Direction

Wind Speed

992mb (Surface)

315° (from the NW)

43 knots (49 mph)

934mb

310° (from the NW)

52 knots (60 mph)

900mb

315° (from the NW)

47 knots (54 mph)

881mb

320° (from the NW)

55 knots (63 mph)

872mb

320° (from the NW)

48 knots (55 mph)

863mb

330° (from the NNW)

59 knots (68 mph)

850mb

340° (from the NNW)

55 knots (63 mph)

784mb

310° (from the NW)

48 knots (55 mph)

505mb

290° (from the WNW)

61 knots (70 mph)

425mb

270° (from the W)

43 knots (49 mph)

414mb

265° (from the W)

35 knots (40 mph)

402mb

275° (from the W)

23 knots (26 mph)

385mb

320° (from the NW)

14 knots (16 mph)

376mb

280° (from the W)

13 knots (15 mph)

Information About Radiosonde:

  • Launch Time: 22:20Z (6:20PM EDT)
  • About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section…

  • Splash Location: 32.35N 75.82W
  • Splash Time: 22:31Z

Highest altitude where wind was reported:

  • Location: 32.43N 75.97W (View map)
  • Time: 22:20:27Z

Lowest altitude where wind was reported:

  • Location: 32.35N 75.82W (View map)
  • Time: 22:31:09Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):

  • Wind Direction: 310° (from the NW)
  • Wind Speed: 47 knots (54 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):

  • Wind Direction: 305° (from the NW)
  • Wind Speed: 50 knots (58 mph)
  • Depth of Sounding: From 376mb to 991mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:

  • Lowest 150m: 159 gpm – 9 gpm (522 geo. feet – 30 geo. feet)
  • Wind Direction: 315° (from the NW)
  • Wind Speed: 46 knots (53 mph)

VORTEX DATA MESSAGE

So, there is certainly a lot of information to be found in those two dozen lines of code. There are a few different kinds of coded reports, and they all tell meteorologists specific information about tropical systems. Another coded report is a Vortex Data Message, which isn’t as cryptic as a dropsonde report but it tells important information about the center of a tropical circulation.

Courtesy Lt. Col Brian Schroeder, U.S. Air Force.The eyewall of Hurricane Felix in 2007, with the moon shining above. Lightning is illuminating the clouds on the left side of the picture, behind the propeller of the C-130J Hurricane Hunter plane.

This information includes coordinates (latitude and longitude) and weather data like temperature, wind.and pressure.

 

Here’s what all of that means:

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 12:53Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5306
Storm Number & Year: 09 in 2011
Storm Name: Irene (flight in the North Atlantic basin)
Mission Number: 35
Observation Number: 14
A. Time of Center Fix: 28th day of the month at 12:29:10Z
B. Center Fix Coordinates: 40°28’N 74°05’W (40.4667N 74.0833W) (View map)
B. Center Fix Location: 19 statute miles (30 km) to the SSW (208°) from New York, NY, USA.
C. Minimum Height at Standard Level: 2,742m (8,996ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 48kts (~ 55.2mph)
E. Location of the Estimated Maximum Surface Wind Inbound: 26 nautical miles (30 statute miles) to the E (85°) of center fix
F. Maximum Flight Level Wind Inbound: From 175° at 71kts (From the S at ~ 81.7mph)
G. Location of Maximum Flight Level Wind Inbound: 52 nautical miles (60 statute miles) to the E (88°) of center fix
H. Minimum Sea Level Pressure: 965mb (28.50 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 10°C (50°F) at a pressure alt. of 3,051m (10,010ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 11°C (52°F) at a pressure alt. of 3,046m (9,993ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 5°C (41°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile

Remarks Section:

Maximum Flight Level Wind: 82kts (~ 94.4mph) in the northeast quadrant at 9:40:30Z
Maximum Flight Level Wind Outbound: 56kts (~ 64.4mph) in the south quadrant at 12:34:30Z
Maximum Flight Level Temp: 13°C (55°F) which was observed 6 nautical miles to the E (90°) from the flight level center

Courtesy Lt. Col Brian Schroeder, U.S. Air Force. Radar imagery of Felix from  Hurricane Hunter Aircraft.

Radar is also used during the Hurricane Hunter flights and can be a very important tool when flying into the center of a storm.  The photo to the left is radar imagery from Hurricane Felix, a Category 5 Hurricane in 2007.

Radar sends out pulses of energy outward and measures the amount of energy that is sent back to the radar receiver from different kinds of precipitation. From this information, meteorologists can determine how far away the precipitation is from the radar and its intensity.

In addition, Hurricane Hunter planes have something called a Step Frequency Microwave Radiometer (SFMR). This instrument is located under the wing of the aircraft and its sensor is pointed downward. It measures the amount of sea foam on the surface of the ocean. Stronger winds means more foam which infers a stronger storm. Hurricane forecasters have been using this instrument for a decade.

National Hurricane Center forecaster Dan Brown told Eyewitness News that getting this data and sending these aircraft into the storm where they can measure the wind and report back to the NHC helps forecasters know how strong the storm is, how big it is and where it is located. He also said this, in turn, helps him make a better forecast.

National Hurricane Center Director Dr. Rick Knabb said, “what we want people to do is have confidence that we’re using the most advanced technology and the expertise on what these data from aircraft mean, so that when you get a warning or forecast, and emergency management tells you to evacuate or take other actions, have confidence in that information and heed those warnings and emergency management instructions.”