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Frequently Asked Questions (FAQ)

FAQs related to...


I need help with navigating the PFDS.

The PFDS web site does not work.

When I try to load a PFDS web page it says it is either missing or I am not authorized to view it.

The state-specific PFDS interactive map page does not load any more.


What NOAA Atlas 14 products are available for download from the PFDS?

How do I obtain a hard copy of NOAA Atlas 14 products?

Do you publish annual maximum series data used to calculate NOAA Atlas 14 precipitation frequency estimates?

What is the easiest way to get NOAA Atlas 14 precipitation frequency estimates from the PFDS?

Can I get NOAA Atlas 14 data through web scraping?

On the Storm Analysis page there is a link to the merged NOAA Atlas 14 product for the contiguous United States. Are estimates from this product the same as the ones I can retrieve from the PFDS for any location?

Why do I see inconsistencies in some NOAA Atlas 14 estimates at boundaries of different NOAA Atlas 14 volumes?

After downloading and uncompressing a NOAA Atlas 14 ArcInfo ASCII grid I end up with a *.ver file, but ArcGIS 9.x does not recognize it when I try converting it to an ESRI Binary Grid using the Spatial Analyst Extension. Additionally, my decompression software still recognizes the *.ver file as a compressed file.

Rainfall intensity or depth is sometimes expressed as a function of duration and frequency. Where can I find these equations and related coefficients in NOAA Atlas 14?

Considering the significant uncertainty associated with 500- and 1000-year precipitation frequency events, why have you decided to publish them in NOAA Atlas 14?

Is there a copyright protection on using NOAA Atlas 14 products from the PFDS, or can I include one in a publication without obtaining explicit permission from NOAA?

The NOAA Atlas precipitation frequency estimates differ from some of the other resources that I have. Which are more accurate? Which should I use?

When will NOAA Atlas 14 precipitation frequency estimates be available in my state?


What is the difference between Annual Exceedance Probability (AEP) and Average Recurrence Interval (ARI)?

What is a 100-year rainfall event and how often is it exceeded?

Why do 1000-year (100-year) events happen so often?

How can I calculate exceedances for a storm event?

May I use your estimates directly as an input to a watershed model?

How do you address impacts of climate change on precipitation frequency estimates?


I do not see any information on current PMP projects in your Quarterly Progress Reports. Are you currently working on updating PMP estimates anywhere in the USA?


Where can I find historical rainfall information?

I do not see my question listed here. Is there another related FAQ list I could access?

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