Comments And Discussion Re NWS Short Term Forecasts

As part of a post back on August second, I included the following: 

... the NWS has another huge "Short Term Forecast" area issued (see below with its text) for almost all of southeastern Arizona. While these products usually focus in on very specific areas expected to experience significant weather during coming hour or two, there have been a number of similar, very large forecasts issued, when there was little happening, during past few weeks. These seem to be being used as a generic, CYA product, and that is disturbing to me, since lightning flash data, radar, and satellite allow the forecasters to "zoom in" on significant weather, rather than painting things with such a very broad brush approach.

Two members of the NWS have provided comments and explanations concerning the NWS Short Term Forecasts and other related products as follows:

FYI those are "zone" based products and as such can only be put out for zones as a whole. Just like the old" ZFP/zone forecast product. We've basically discontinued using the NOWCast at NWS Phoenix,  instead opting for providing updates via our Twitter feed. I know NWS Tucson does quite a bit on Twitter as well when they've got active weather. They've got an experimental type graphical radar nowcast running on their site.

http://www.wrh.noaa.gov/twc/monsoon/granalyst.php

I think the important thing is that there are multiple ways of getting NWS information, and like all information streams, the resolution (temporal and/or spatial) can vary. Take NOAA Weather Radio - you can only do so much with technology that is 50+ years old. The evolution of that is the Weather Emergency Alerts. Yes, folks still hit our website, but more get information from us via social media. Ultimately they all work together.

Paul Iñiguez

Science & Operations Officer, NOAA/NWS Phoenix, AZ

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This partially in response to Paul ... we are primarily issuing the Nowcast to populate the web page as Paul described. The script we are using grabs the first segment, so we usually group most zones together.  Since it is a forecast, it sometimes covers a larger area than radar coverage at issuance time.

In Tucson, another primary user of the Nowcast is the TV media. They receive it via Nws chat instant messaging as soon as it is transmitted.Like NWS Phoenix, we post a lot of Nowcast-like information on Twitter, including Happening NOW graphics.

I'll be happy to further elaborate on any of this if needed.

I would add that the Significant Weather Advisory (SPS) is the product we usually use to convey more detailed storm-specific information. The polygon is prominently displayed on the web page and is posted to Twitter.

Additionally, the SPS scrolls on The Weather Channel and alerts on smart phone apps such as the FEMA Weather Alert App. Using the NOW in a similar way is not optimal since it is issued by zone as you mentioned. We do however have the flexibility to use the NOW on a broader areal scale and for a longer time period, even up to 6 hours. Certainly that means it will contain less detailed information when scaled up as such.

Ken Drozd

Warning Coordination Meteorologist
National Weather Service Tucson