Hurricane Advisory Times: Regular, Intermediate and Special Updates
Learn when to check NHC advisories, how special updates differ, and why a forecast valid time is not its publication time. Includes a fictional reading worksheet.
Do not rely on one saved update
NHC distinguishes regular, intermediate and special public advisories. Intermediate public advisories are issued at three-hour intervals when coastal watches or warnings are in effect. Special advisories can be issued at other times for significant changes. A familiar schedule is not a reason to ignore an intervening update.
Read the issue time and forecast time separately
A forecast describes conditions expected at a later time. Its issuance timestamp describes when that forecast was released. In a fictional exercise, a product issued at 09:00 UTC contains a point valid at 21:00 UTC. The point is an expectation twelve hours ahead, not a measurement already observed at publication. Keep both labels when writing a caption.
Intermediate does not mean unimportant
NHC product guidance permits U.S. tropical cyclone watches and warnings in regular or intermediate public advisories. Do not assume an intermediate message is merely a repeated position report. Read its changes and warning sections before comparing it with an earlier saved copy.
Check the graphic as well as the text
NHC notes that graphics can be updated with intermediate or special advisories. Our practical check is to compare the storm name, basin, date and issue time on the graphic with the text being discussed. If the copies differ, obtain matching current products rather than combining a new caption with an old map.
Source: NHC graphic descriptions ↗
A sharing worksheet, not a storm forecast
The example below contains no real cyclone and makes no prediction. For a real update, save the original link and advisory identifier, distinguish observed information from forecast information, and include the timezone. Check local instructions independently of the center track. A scheduled social post should be rechecked before publication; do not leave an old advisory queued as if it were current simply because its headline still sounds plausible.
Put it into practice
| Field or example | Value or action | Meaning |
|---|---|---|
| Issued 09:00 UTC | Publication time | When this fictional forecast was released. |
| Forecast valid 21:00 UTC | Future forecast point | Not an observation at 09:00. |
| A newer special update appears | Read it now | Do not wait solely for the expected regular cycle. |
| Graphic and text have different times | Find matching current products | Do not attach new text to an old forecast map. |
For the difference between alert types, read our flood watch versus warning explainer. Check source retrieval times before relying on a stored report.
Official sources
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