Friday, March 04, 2016

Global Models' Trends Going Wrong Way For Us

The anticipated pattern change for early March is underway, but the chances for a big precipitation event for southeastern Arizona seem to be diminishing as the first weather event in more than a month approaches. The GEFS QPF plumes above (from the 06 UTC forecasts last night) show this trend. The most fickle of the GEFS members has been the operational version of the model (blue line) which has gone from very wet (see post below on March 1st) to its current forecast of no precipitation at TUS.

The graphic below shows the 7-day forecast for accumulated precipitation (from the operational member's 06 UTC forecast). The model now forecasts the 500-mb short wave that digs toward the Southwest to stay to our west and then to our south - this brings the most significant aspects of the event to Mexico and then northeastward to New Mexico and Texas. We see an all too familiar donut hole over southern Arizona in this forecast. In fact this current forecast is now very much like the long-range one that was posted below way back on February 26th.

The IVT forecasts from the GEFS (available at the Plymouth State link in post immediately below) illustrate the current trend for next Monday (above) and Tuesday (below), as high probabilities for significant vapor transport slide far to our south. This is a very nice forecast product, even though its current trends are disappointing wrt our long period of very dry weather. The time frame here is still 3 to 4 days out, so we can continue to hope for a better outcome.

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