An area of disturbed weather formed on the 11th west of Panama and
The wave that spawned this system emerged off the coast of Africa on August 30th and 31st and
helped spawn Erika. Light winds aloft and very warm water temperatures allowed Nora to
develop into a tropical depression by early the 16th, a tropical storm later that day, and a
hurricane late on the 17th. The cyclone moved west-northwest, steered by the climatological
500 hPa anticyclone over northwest Mexico. From the 18th to the 20th, Nora stalled. A storm
system in the West most likely eroded the western part of the mid-level ridge, causing the stall.
Weakening ensued as Nora sat over the same patch of water, upwelling
the waters in its vicinity.
The ridge to its north rebuilt as the Western cyclone spun into the Midwest, allowing Nora to
assume a parabolic course around its periphery, restrengthening to a category four hurricane.
Nora then moved roughly along Linda's path...a hurricane that preceded Nora by several days.
This caused renewed weakening in the cooler waters upwelled by Linda. A cutoff low formed
northwest of the cyclone on the 23rd, allowing Nora to turn northward and accelerate. The
cyclone remained at hurricane status during both landfalls....near Point Eugenia and the Mouth
of the Colorado river.
Weakening to a tropical storm, Nora crossed into the Desert
of the United States.
Sustained winds of tropical storm force were recorded at Yuma. Although weakening to a
tropical depression as it moved across California and Arizona, the circulation aloft did not
have time to spin down. Strong winds, nearing hurricane force, downed many trees across
southwestern Utah, at an elevations of 10,000 feet and higher. Heavy rains along the
Mogollon Rim closed in on 12 inches in the Harquahala mountains....with numerous locales
reporting 3 to 4 inches...more than many of them normally see in a year. Some lighter rains
fell across the central Rockies, with some moisture making it into the northern Plains. Below
is the track of the cyclone, provided by TPC/NHC.
Below are the storm total rainfall maps for Nora, created using
totals collected from the National Climatic
Data Center, the Maricopa County ALERT system, the NHC tropical cyclone report, and the Comision del Agua, part
of the Mexican National Weather Service. The maximum in the United States is located in the higher terrain of
southwest Arizona to the right of the track. In Mexico, the highest amounts in western portions of the country were
near the entrance to the Gulf of California. In eastern Mexico, the combination of the precursor Nora disturbance
and an upper low over the Gulf of Mexico led to heavy amounts just west of Guatemala.
Below is the calendar for Daily Precipitation Maps. Note that
the 24-hour periods end
at 12z that morning.