Saturday, October 22, 2022

Wind Then Showers Possible



Beautiful sunrise colors over the Rincons at 6:30 am MST this morning.

The forecasts from the WRF model at Atmo this morning have shifted the strong and gusty winds to today, rather than tomorrow (see previous post). Forecast above is from the 12 UTC WRF-RR and is for steady wind speeds at 4:00 pm this afternoon.

The 500 mb analysis is quite interesting this morning (above from SPC). A very strong and cold short-wave trough is digging south across northwest US, while a weaker, closed-low remains west of Baja. The models continue to eject this feature eastward across northern Mexico ahead of the stronger trough. This makes for a tricky forecast situation - assuming the Baja low does move across northern Mexico. Key question would be how much drying would occur as the southern low opens and moves eastward.

The morning sounding (above from SPC) for TWC/TUS has strong southwest winds above 850 mb, as well as some CAPE. The sounding indicates there could be isolated storms/showers across southeastern Arizona this afternoon.

The GEFS plumes shown here are from the 06 UTC runs. The QPF forecasts for the airport (above) are a bit erratic wrt to timing and amounts; however, most agree that rain at airport is most likely tomorrow night into early Monday. Forecast temperatures (below) take a dive tomorrow and Monday with temperatures about 10 to 15 degrees cooler. This will be a very noticeable change, compared to past week.

The 12 UTC WRF-RR forecast for precipitation amounts through 5:00 am Monday morning (below) indicates showers for most of eastern Pima County. I will look forward to seeing what's in the gauge Monday morning. Current NWS forecast is for a 40% chance of measurable rain at the airport Sunday night.


Finally, looking south, tropical storm Roslyn has intensified rapidly and is now the fourth Cat 4 hurricane in the eastern Pacific this season. Visible image of the storm (above) is from 6:30 am, and current NHC forecast (below) brings the storm ashore in western Mexico, north of Cabo Corrientes as a major hurricane.

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