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How To Read The Forecast/Advisory


The Forecast/Advisory is generally composed of several easily identified sections. These sections if present in the advisory will always occur in the order specified here.

Click on each section title to see the section highlighted and read the brief description of the section contents in the example Forecast/Advisory from Hurricane Isabel.

The Basic Sections of the Forecast/Advisory

  1. WMO Header
  2. Watches/Warnings and News
  3. Storm Location
  4. Storm Movement
  5. Minimum Central Pressure
  6. Eye Size Estimate
  7. Max Sustained Wind, Wind Radii, and 12-Foot Wave Height Radii Section
  8. Repeat
  9. 12-Hour Forecast
  10. 24-Hour Forecast
  11. 36-Hour Forecast
  12. 48-Hour Forecast
  13. 72-Hour Forecast
  14. 96-Hour Forecast
  15. 120-Hour Forecast
  16. Request for Ship Reports
  17. Next Advisory
Click here to highlight all of the basic sections.
000
WTNT23 KNHC 180229
TCMAT3

HURRICANE ISABEL FORECAST/ADVISORY NUMBER 42
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132003
1500 UTC TUE SEP 16 2003


WMO Header Section

This section contains the assigned United Nations World Meteorology Organization (WMO) document identifier, the National Weather Service document identifier, the storm type and name, advisory number, the issuing center (in this case the NHC), and the date and time for the advisory, and a tropical cyclone identifier (the format is BBNNYYYY, BB=Basin (AL=Atlantic, EP=Eastern Pacific), NN=sequence number, YYYY=year).

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AT 11 AM EDT...1500 UTC...A HURRICANE WATCH IS IN EFFECT FROM LITTLE
RIVER INLET SOUTH CAROLINA TO CHINCOTEAGUE VIRGINIA...INCLUDING THE
PAMLICO AND ALBEMARLE SOUNDS...CHESAPEAKE BAY SOUTH OF NORTH BEACH
MARYLAND...AND THE TIDAL POTOMAC. A HURRICANE WATCH MEANS THAT
HURRICANE CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY
WITHIN 36 HOURS.

HURRICANE WARNINGS MAY BE REQUIRED LATER TODAY OR TONIGHT.

AT 11 AM EDT...A TROPICAL STORM WATCH IS IN EFFECT SOUTH OF
LITTLE RIVER INLET TO SOUTH SANTEE RIVER SOUTH CAROLINA. A
TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 36 HOURS.

A TROPICAL STORM WATCH MAY BE REQUIRED NORTH OF THE HURRICANE WATCH
AREA LATER TODAY OR TONIGHT.


Watches/Warnings and News Section

This section contains important news as well as any Watches and/or Warnings (hurricane and/or tropical storm) that have been issued or discontinued for coastal areas.

<< Previous Section  -- Back to top  -- Next Section >>
HURRICANE CENTER LOCATED NEAR 27.4N 71.2W AT 16/1500Z
POSITION ACCURATE WITHIN 20 NM


Storm Location Section

This section contains the location of the storm center in latitude and longitude with the issuance date/time of the product and an estimate of the accuracy, in nautical miles, of the position based on the type, quality, and resolution of the fix platform used.

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PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 330 DEGREES AT 7 KT


Storm Movement Section

This section details the current motion of the storm in knots or nautical miles per hour (1 knot = 1.15 mph), with the direction expressed in terms of 16 compass points and to the nearest 5 degrees (true) of azimuth (e.g. 360°=North, 90°=East, 180°=South, and 270°=West).

<< Previous Section  -- Back to top  -- Next Section >>
ESTIMATED MINIMUM CENTRAL PRESSURE 959 MB


Minimum Central Pressure Section

This section gives the minimum central pressure of the storm in millibars. Whenever a storm is only threatening the U.S., the wind speed in km/hour is usually discontinued. Although central pressure is not a hazard it can sometimes be an indicator of future changes in intensity. Strengthening oftentimes follows a decrease in pressure while weakening generally follows an increase in the pressure.

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EYE DIAMETER 25 NM

Eye Size Estimate Section

This section gives an estimate of the diameter of the eye of the tropical cyclone based on aircraft reconnaissance and/or radar data.

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MAX SUSTAINED WINDS 90 KT WITH GUSTS TO 110 KT.
64 KT.......105NE 90SE 40SW 70NW.
50 KT.......140NE 140SE 60SW 90NW.
34 KT.......200NE 200SE 100SW 150NW.
12 FT SEAS..600NE 300SE 300SW 600NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.


Max Sustained Wind, Wind Radii, and 12-Foot Wave Height Radii Section
This section gives the maximum sustained 1-minute wind speed, gusts, and map coordinates that indicate the extent of the wind field and the wave field. Wind quadrant values are quadrant radii for several wind values (if present): tropical storm force winds (34 knots), storm force winds (50 knots), and hurricane force winds (64 knots). The map coordinates are in compass directions radiating out from the center of the storm along the direction and distance in nautical miles as indicated. For example:
64 KT. . . . . . 105NE   90SE   40SW   70NW.
means that winds of 64 Knots (74 MPH) are possible anywhere within that quadrant out to 105 Nautical Miles (121 Miles) Northeast, 90 Nautical Miles (104 Miles) Southeast, 40 Nautical Miles (46 Miles) Southwest, and 70 Nautical Miles (81 Miles) Northwest, of the estimated center of the storm.

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REPEAT...CENTER LOCATED NEAR 27.4N 71.2W AT 16/1500Z
AT 16/1200Z CENTER WAS LOCATED NEAR 27.0N 71.0W


Repeat Section

This section repeats the current center location and the location from the last advisory as a check against transmission errors and to assist mariners in charting the storm's movement. This section also contains the actual location of the storm 3 hours prior to the time of the advisory (in this case, the center at 1200Z or 8AM EDT / 7AM CDT on the 11th was 27.0°N 71.0°W).

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FORECAST VALID 17/0000Z 28.4N 71.8W
MAX WIND 85 KT...GUSTS 105 KT.
64 KT...105NE 90SE 40SW 70NW.
50 KT...140NE 140SE 60SW 90NW.
34 KT...200NE 200SE 100SW 150NW.


12-Hour Forecast Section

This section gives the 12-hour forecast for the tropical cyclone's position, the maximum sustained wind and gusts, and an estimate of the size of the wind field using the same threshold wind values as in the Wind and Wave Radii section. As before, the map coordinates of the wind field are compass directions and radial distances out from the center of the storm in nautical miles.

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FORECAST VALID 17/1200Z 29.9N 72.6W
MAX WIND 85 KT...GUSTS 105 KT.
64 KT...105NE 90SE 40SW 70NW.
50 KT...140NE 140SE 60SW 90NW.
34 KT...200NE 200SE 100SW 150NW.


24-Hour Forecast Section

This section gives the 24-hour forecast for the tropical cyclone's position, the maximum sustained wind and gusts, and an estimate of the size of the wind field using the same threshold wind values as in the Wind and Wave Radii section. As before, the map coordinates of the wind field are compass directions and radial distances out from the center of the storm in nautical miles.

<< Previous Section  -- Back to top  -- Next Section >>
FORECAST VALID 18/0000Z 31.7N 73.9W
MAX WIND 90 KT...GUSTS 110 KT.
64 KT...105NE 90SE 40SW 70NW.
50 KT...140NE 140SE 60SW 90NW.
34 KT...200NE 200SE 100SW 150NW.


36-Hour Forecast Section

This section gives the 36-hour forecast for the tropical cyclone's position, the maximum sustained wind and gusts, and an estimate of the size of the wind field using the same threshold wind values as in the Wind and Wave Radii section. As before, the map coordinates of the wind field are compass directions and radial distances out from the center of the storm in nautical miles.

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FORECAST VALID 18/1200Z 33.8N 75.6W
MAX WIND 95 KT...GUSTS 115 KT.
50 KT...150NE 150SE 90SW 120NW.
34 KT...250NE 200SE 125SW 150NW.


48-Hour Forecast Section

This section gives the 48-hour forecast for the tropical cyclone's position, the maximum sustained wind and gusts, and an estimate of the size of the wind field using the same threshold wind values as in the Wind and Wave Radii section. As before, the map coordinates of the wind field are compass directions and radial distances out from the center of the storm in nautical miles. Please note that 64 knot (hurricane force) wind radii are never provided at this forecast time period.

<< Previous Section  -- Back to top  -- Next Section >>
FORECAST VALID 19/1200Z 39.0N 79.0W...INLAND
MAX WIND 45 KT...GUSTS 55 KT.
34 KT...250NE 200SE 0SW 0NW.


72-Hour Forecast Section

This section gives the 72-hour forecast for the tropical cyclone's position, the maximum sustained wind and gusts, and an estimate of the size of the wind field using the same threshold wind values as in the previous section. The map coordinates of the wind field are compass directions and radial distances out from the center of the storm in nautical miles, as in the Wind and Wave Radii section. In the example the storm was forecast to move inland and drop in intensity to tropical storm strength by Day 4. Please note that 64 knot (hurricane force) wind radii are never provided at this forecast time period.

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EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 275 NM
ON DAY 4 AND 375 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 20/1200Z 47.0N 78.5W...EXTRATROPICAL
MAX WIND 30 KT...GUSTS 40 KT.


96-Hour Forecast Section

This section gives the 96-hour extended forecast for the tropical cyclone's position, the maximum sustained wind and gusts, and an estimate of the size of the wind field using the same threshold wind values as in the previous section. The map coordinates of the wind field are compass directions and radial distances out from the center of the storm in nautical miles, as in the Wind and Wave Radii section. Additional notes on track errors are added for the 96 and 120 hour forecasts. In the example the storm was forecast to become extratropical as it fell below tropical storm strength. Due to significant uncertainties, wind radii are never provided for this forecast time period.

<< Previous Section  -- Back to top  -- Next Section >>
OUTLOOK VALID 21/1200Z 54.0N 71.0W...EXTRATROPICAL
MAX WIND 30 KT...GUSTS 40 KT.


120-Hour Forecast Section

This section gives the 120-hour extended forecast for the tropical cyclone's position, the maximum sustained wind and gusts, and an estimate of the size of the wind field using the same threshold wind values as in the Wind and Wave Radii section. As before, the map coordinates of the wind field are compass directions and radial distances out from the center of the storm in nautical miles. In the example the storm was forecast to become extratropical as it fell below tropical storm strength. Due to significant uncertainties, wind radii are never provided for this forecast time period.

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REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 27.4N 71.2W


Request for Ship Reports

This section is a request for ship reports from any vessels in the general vicinity of the tropical cyclone.

<< Previous Section  -- Back to top  -- Next Section >>
NEXT ADVISORY AT 16/2100Z


Next Advisory Section

This section gives the scheduled release time of the next advisory, which will always be 6 hours after the actual time of this product (i.e. 0300Z, 0900Z, 1500Z, and 2100Z).

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FORECASTER FRANKLIN


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Page last modified: Monday, 10-Jan-2011 14:35:50 UTC