Weather Features Of Interest Midweek

First - easterly winds have been been surfacing this morning down at the airport after midnight, making the temperature jump up and down. The low at TUS was a bit after midnight and was 38 F. Winds remain calm here at the house and morning low was 23 F. So there was quite a temperature gradient between here and airport - especially around 6:00 am MST when the TUS temperature had jumped up to 52 F.

Currently there is a middle and upper-level cyclone centered southwest of the southern end of Baja - above is 12 UTC NAM analysis at 500 mb this morning (January 5th). This feature is forecast to move northward during the next 3 days, impacting southeastern Arizona as it moves toward the north end of the GoC.

Graphic below is from today's early WRF-NAM model (on the 5.4 km grid) at Atmo and shows PW valid at 5:00 am MST this morning. The PW is very low currently all the way down the GoC.

However, as the 500 mb cyclone moves northward, PW increases markedly all the way into southeastern Arizona. Forecast of PW from WRF-NAM above is valid at 11:00 pm on Wednesday night (January 7th). The model forecasts very light showers along the Borderlands at this time.

The situation will be further complicated by a strong, back-door cold front crossing the Continental Divide and pushing westward across southern Arizona. Strong downslope winds with this feature (below shows forecast of 10-m winds valid at 11:00 pm MST Wednesday night) will be interacting with the advancing moisture plume from low latitudes. Thus, a complicated weather scenario for us to watch here, while most of the country will be focused on the cold and extreme high pressure associated with the arctic air mass over the central U.S.