Tuesday, September 6, 2016

Hurricane Newton Aims for Tucson

Hurricane Newton passed Cabo San Lucas early this morning, producing sustained winds at the CSLB7 observing site (735 feet above sea level) reaching 79 mph with a peak gust of 116 mph, both around 2 am MDT.

Source: MesoWest
Model forecasts call for Newton to weaken, but bring a strong slug of moisture into southern Arizona tonight and tomorrow.  The high-resolution NAM loop below shows the sea-level circulation center weakening but tracking across northwest Mexico, eventually reaching Tucson.  Southeast Arizona and New Mexico bear the brunt of the precipitation, especially tomorrow.

There are multiple sources of uncertainty in precipitation forecasts related to landfalling tropical storms, but include (1) track and (2) the chaotic nature of convective storms.  The latter can lead to large spatial and temporal variations in precipitation, even over short distances (see also the Madweather blog).  Last night's NCAR ensemble, for example, produced anywhere from 1 to 4 inches of precipitation at Davis-Monthan AFB near Tucson.

Source: NCAR
The NWS has issued a flash flood watch for most of southeast Arizona and southwest New Mexico and it looks like some impressive gully washers are likely.

Unfortunately, the moisture will not be coming to northern Utah.  Did you know it's been since June 13 since we had more than 0.08" at the Salt Lake City Airport!  If only Newton's apple fell a bit further from the tree.  

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