Friday, June 10, 2016

Big Storm Day Possible Today With Severe Winds

This morning's sounding from TWC (above) on campus is quite impressive with PW up to 1.46 inches and substantial CAPE, given some decent heating later this morning and early afternoon. Steering level winds for thunderstorms are from the northeast this morning but they will gradually be shifting toward the southeast, as a short-wave disturbance passes by to our west.

The circulation with this disturbance (located southwest of Nogales) is visible in the 8:00 am MST satellite image below. The cloud field is extensive and is perhaps the most significant wild card in today's various forecasts. There is currently more cloudiness off to our southeast than has been captured in the model forecasts - so the degree to which we get solar heating today will need to be monitored.

The WRF model from 06 UTC runs at Atmo forecasts solar IR to be intense by noon - both the WRF (above) and the GFS (below) variants of the model forecast over 1000 W/m2 of global horizontal irradiance at noon. The associated heating drives the active development of intense convection forecast by the models.

The details of storm coverage and intensity again vary between the two versions of the models, with the heaviest rains forecast  from most of Cochise County out west to central Pima County when the two forecasts are blended together. Shown here are are accumulated precipitation forecasts though 7: 00 am tomorrow morning (NAM above and GFS below). Suffice to say that a large area of southeast Arizona has the potential for strong to severe thunderstorms - quite something for June 10th.

Strong outflow winds are also different between the two WRF versions. Shown here are forecasts of 6:00 pm MST 10-m winds from the NAM (above) and GFS (below). However, both versions forecast very strong winds in the I-10 dust storm regions in Cochise County and also between Tucson and Phoenix. The GFS forecast would indicate a chance of an evening haboob impacting parts of the Phoenix metro area. Definitely a day for caution and also a threat for severe that SPC seems to have overlooked in their current outlooks.

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