Tropical Storm Newton Heads Our Direction

Tropical Storm Newton is currently just west of Cabo Corrientes and heading northward. The IR image above is from 6:30 am MST this morning and the MIMIC PW analysis below is from 5:00 am.

This morning's NHC forecast for the track of Newton is shown above, with the intensity forecast indicating NHC expects Newton to remain a TS. However, the Mexican Weather Service has issued a hurricane warning for the southern end of Baja, as the storm is expected to approach rapidly across very warm waters. The NHC notes in its current discussion:

Low shear, a moist environment, and very warm water should allow
Newton to steadily strengthen until it reaches the Baja California
peninsula. In fact, rapid intensification is a possibility as the
SHIPS Rapid Intensification Index shows a 40 percent chance of a
30-kt increase in the winds during the next 24 hours.  Based on the
expected conducive environment, the NHC intensity forecast remains
near the high end of the guidance during the next day or two. After
Newton passes the Baja peninsula, weakening should occur due to land
interaction and an increase in vertical wind shear.

Shown above in the two graphics are GEFS plumes from the 06 UTC forecast last night of QPF (top) and PW (just above). The range of QPF from the different members' forecasts for TUS (the airport) is almost 3 inches and the range of PW is around an inch. This reflects the fickle nature of our actual observed weather when an old TS comes near.

The official NWS morning forecast for the airport grid box is shown below. The POPs stay at 50% or less for Wednesday and Wednesday night, but the forecast also calls for Heavy Rain during those periods.

Finally, I took a look at the 06 UTC WRF forecasts from Atmo. Both versions forecast Newton's remnant 500 mb circulation to cross central Pima County. The composite radar forecast above (from the WRF-GFS,valid at noon on the 7th) is quite impressive. The accumulated precipitation forecast from the GFS version (below valid through 11:00 am on the 8th) forecasts the core area of heavy rains directly into central Pima County and parts of the metro area. Amounts on the Catalinas reach 6 to 8 inches in the model forecast. The NAM version of the forecasts shifts the core of heaviest rainfall eastward across Cochise County. Regardless of how the actual details evolve, an interesting work week on tap.