Extreme Upcoming Rain Event In Phoenix (Tucson: stations, best, areas)

[AJ1013]

Models have been remarkably consistent over the past week bringing copious amounts of rainfall to the deserts of the Southwest, particularly in Arizona. With the potential event now less than five days away I thought I should start a thread to document it. Interestingly, even though Tucson is normally significantly wetter than Phoenix, Phoenix is the city most consistently forecasted to be inundated by this event

Here are some forecasts for locations in Arizona as well as some precipitation maps:

Tucson:




Phoenix:




Precipitation Maps

EC:




GFS:




Feel free to share your thoughts and input as this is an ongoing event

[cgl77]

Well, as a native to the southwest, I always keep possible rain events in the realm of hoped for but not expected. Of course, no one wants destructive rain and flooding like southeast Texas is experiencing.

[sh9730]

Everything I have read shows a majority of the models predicting LESS than 2" of rain in central AZ with much uncertainty still in said models.

Check the graph in this article from the NWS:

https://www.12news.com/article/weath...0-b1721f6427f1

[Valley Native]

Like any other prediction for storms & rain by the so called experts at the NWS, I'll believe it when I see it. Sometimes the predictions for heavy rain have become reality, such as last October. But even this last winter, some of the forecasts for heavy rain turned out to be little or nothing at all. Don't get your hopes (or fears) up ahead of time. Be prepared, but wait & see what happens. My experience with NOAA is they're right only about half of the time about rain forecasts, but correct nearly 100% of the time when it comes to "sunny & warm/hot" forecasts here in Phoenix.

[Ponderosa]

Simmer down there. Long experience says to wait until it is in the bucket to call for rain in Phoenix. I can't begin to count all the times I have put out fertilizer on a forecast of rain only to have it sit there dry. I'm with the I'll believe it when I see it side on this storm.

[wase4711]

agree with most folks here..these "forecasters" are wrong when it comes to rain/storms about 80% of the time, so until I see actual water on the ground, I don't believe it one bit..

[Valley Native]

As an example of how inept and uncertain the NWS is on rain predictions, here is what the NOAA forecast discussion said just two days ago:

The GEFS plumes for Phoenix indicates a model mean of
1.20", a slight downtrend from previous runs, while the current
precip forecast from the Weather Prediction Center shows
widespread 0.50-1.00" with a swath of 1.50-2.00" across south-
central Arizona. The possibility that many areas see fairly less
rain does exist but the potential that some places see significantly
more is a concern.

https://forecast.weather.gov/product...=28&glossary=1

Now here is their most recent outlook:

The GEFS plumes QPF continues
its downward spiral with the latest mean value showing around
0.40" of rain for Phoenix, a stark drop from nearly 1.50" just a
few days ago. Meanwhile, the EPS mean rainfall is still a bit
wetter at nearly 1.00" through Tuesday, but this value is also
following a downward trend. While the potential for heavy rainfall
is present, together, both of these model trends cast some doubt
on the coverage of heavy rain. Nevertheless, nearly all members,
as well as other guidance, show measurable rainfall across much of
the forecast area.

https://forecast.weather.gov/product...n=1&glossary=1

This is very typical of the NWS: they hype up the rainfall predictions early on (almost to the point of being far fetched), then they usually downgrade the rain chances and the rainfall amounts the closer we get to the actual storm. Bottom line: the so called experts don't know what's going to happen, and neither do we. It's always best to be prepared, but I wouldn't anticipate anything for the record books as of now.

[Ponderosa]

Looks like most of us will get a few drops and that's about it. Typical.

[phetaroi]

Originally Posted by Valley Native

As an example of how inept and uncertain the NWS is on rain predictions...

It isn't a question of being inept. It's a question of weather being a highly dynamic phenomenon and a literal flood of data from both satellites and ground stations coming in during a constantly changing period of time.

[AJ1013]

Based on the latest modeling and forecast trends we’re currently expecting 1.5” to 2.5” of rain across most of the valley. Not an all time record but up there for sure and most certainly a very significant event. Threat of severe weather tomorrow as evidenced by the WPC Severe Weather Outlook.