Sunday, August 02, 2009

Is Today the Day?


Another terribly suppressed day yesterday that extended the dry-out to 7 consecutive days. During these seven days 1 site (Anamax) in the Pima County ALERT network reported rainfall (0.16”) on one day (Friday). Can’t help but wonder if this is a record? The “monsoon” has been essentially in a failure mode for Arizona for a week (break seems too mild a term). One could also say that to our northwest in the Phoenix area that it is debatable as to whether there has even been an onset.

Much of yesterday’s discussion is still in play. But there are several things of note: Low-level moisture has pushed in from southern New Mexico during yesterday evening and last night. Between 6 pm and 11 pm surge-like increases in surface dewpoint occurred at Hachita Valley NM, Guthrie, Rucker, and Safford with Safford (yes! Safford) having the highest PW (this side of the border) shown in the time series at Atmo weather page. To the south, moisture remains high and the visible image for 1445z shows middle cloud floating around this morning. There may be a plume of lower cloud moving north between Sells and Yuma. So moisture is encroaching from the east and south, and today will apparently be a day of important change. The morning sounding at Tucson is frankly a disaster with bad data on top of an incredible dryness; whereas, the El Paso sounding looks much more like August (note GPS PW data is not available for El Paso this morning but sounding data indicate almost 3 cm).
The NAM forecast continues to bring the embedded IT at 500 mb (mentioned yesterday) toward southeast Arizona this evening, and then moves it very slowly toward north for next 48 hours, along with a distinct upswing in forecast precipitation coverage. In the longer term, the GFS has now joined the ECMWF in predicting the Pacific trough inland, returning to a very non-August-like and dry pattern later this week.

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