Much-needed rain may finally be on its way

AUSTIN (KXAN) — With barely a half-inch of rain in Austin this month and worsening drought conditions, our luck may be about to change.

We are seeing more consistent signs pointing to more rain opportunities during the last third of May.

The importance of the rains of May and June

May is typically our wettest month of the year, averaging over 5″ of rain in Austin. Our wettest period of the year usually ends in mid-June as we head into a hot summer. July-August is usually hot and dry, and tropical systems are our best bet for rain along with a few isolated thunderstorms.

If we head into those hotter summer months with very dry soil, we have the potential to have dozens of triple-digit days as the drought exacerbates. Alternatively, entering the summer with normal precipitation and moist soils would help keep temperatures down during the summer and improve drought and our lake levels.

That is why it is very important that it rains a lot as we finish May and start June.

What do long-term models suggest?

Several of our long-term computer model suites paint a promising, but not drought-ending, outlook for the last third of the month beginning next weekend (May 21-22).

Here is the rainfall distribution for the whole of Europe and America. Pay close attention to the “Media” line.

Precipitation propagation from the European computer model (Weatherbell)
Precipitation propagation from the European computer model (Weatherbell)
GFS (US) Computer Model Precipitation Spread (Weatherbell)
GFS (US) Computer Model Precipitation Spread (Weatherbell)

What do those graphs mean?

Let me first explain what a “set” is:

Multiple iterations of the same computer model are run with slightly different initial conditions, and those different runs of the model are known as ensembles. The ensemble mean is the average result of those various iterations of the same model. In this case, the ensemble mean looks at the average precipitation forecast for the end of the month.

Both sets of computer models suggest about 1-1.5″ of additional rain in Austin by the end of the month. Remember, we need about 4.5″ of rain by the end of May just to have a normal month, so this rain may not fix the drought, but it is a sign of much needed wet weather in our future.

Certainly we may end up with more than that or less rain than that, as the downpours we normally get in May can have far reaching totals, but at least the signs point to more rain than we’ve been in weeks.

What is the forecast from the Climate Prediction Center?

NOAA and CPC agree on a wetter outlook! Both the 6-10 day rain forecast and the 8-14 day rain forecast are likely to favor wetter than normal weather. Remember, in this wet month of May, even “normal” rains would be good news for us.

Precipitation Forecast 6 to 10 days (CPC)
Precipitation Forecast 6 to 10 days (CPC)
Precipitation forecast for 8 to 14 days (CPC)
Precipitation forecast for 8 to 14 days (CPC)

When will confidence in rains increase?

We’ll know more as we get closer, simple as that. We still have a hot, dry week to go before we can start to get too excited about the prospect of rain. Long-term prospects are not evangelical, and sometimes the wettest trends can be reversed.

Stay with the KXAN First Warning Weather team as we continue to track the heat and the outlook for needed rain.

Leave a Comment