Saturday, April 26, 2014

Bit Of Everything For Arizona Today

The Tucson NWS currently has a variety of alerts and warnings out for southeastern Arizona - above graphic is from the NWS web page. The emphasis is on strong winds, blowing dust, and wildfire hazards. The forecast also includes a 30% chance of rain at the airport today. At 7 am this morning gusty winds of 25 to 35 mph were common across much of the state, and the exposed RAWS site at Guthrie was already hitting 52 mph. Snow and rain were mostly confined to the north half of the state at sunrise.

The 500 mb analysis for 12 UTC, from the current NAM model, indicates that a powerful vorticity maximum is centered over southern California. The upper-air sounding at San Diego indicated very strong wind speeds of 110 kts at 500 mb. The vorticity center will move across central to northern Arizona today, preceded by a strong Pacific cold front, that has already moved about half way across the state. The Tucson morning sounding from the NWS office on campus - below for 12 UTC from the SPC - shows very strong low-level winds reaching 50 kts at 700 mb. The PW is about half an inch.

The early WRF-NAM forecast from Atmo continues to forecast strong winds across southern Arizona. The above, 10-m agl,  forecast is valid at 11 am MST, when the model forecasts strongest winds across the Tucson metro area. The model also predicts PW amounts to peak across eastern Pima County around 11 am to noon - below is forecast of PW valid at 11 am - with amounts reaching to around three quarters of an inch. The model continues to forecast very sparse rainfall at low elevations and keeps measurable amounts mainly at high elevations, especially across the Rim country to the far north. At bottom is the early WRF-NAM forecast of total precipitation though midnight tonight. So, a turbulent day on tap for Arizona and the Southwest.

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