Monday, August 22, 2011

Little Change

Little to report today. There were isolated, higher elevation storms yesterday afternoon, much as forecast by the early Atmo run of the WRF-GFS. The model has nicely captured the slow dry down that has occurred. PW across southern Arizona this morning runs from around an inch in the west to near 1.4" in the southeast. There were no reports of measurable rainfall yesterday anywhere in all of southeast Arizona - at NWS, ALERT and RAWS sites - although 2 RAWS stations in the White Mountains of Greenlee County had light rainfall. Radar did indicate isolated thundershowers during the afternoon, especially to the south and east of Tucson and up in the White mountains. Anvil cloud spread across the late afternoon skies here in Tucson.

Today looks to be quite similar, with isolated mountain storms as the dry down continues to some degree. The Tucson 1200 UTC sounding today appears to have at most a sliver of CAPE at the top of this afternoon's BL. Winds continue very light below 400 mb, while the upper-troposphere continues to have
southerly winds of 20 to 25 kts.

Early run of the WRF-GFS indicates some rainfall through midnight tonight at favored storm locations.
As mentioned in an earlier post, most weather attention this week will be on Hurricane Irene and its impacts along the east coast. Here in the Southwest, the 500 mb anticyclone will linger over New Mexico and drift toward the Four Corners. Then during the latter part of week (partly in response to events in the East), the anticyclone will shift northwestward into the Great Basin. Thus, some hope that we'll eventually have some winds in the lower half of the troposphere before week's end.

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