Hurricane Simon (IR image above is from 1330 UTC) has been weakening rapidly this morning, as it moves northward over cooler SSTs. However, mT air with high PWs has been inching northward up the GoC, even though surface winds are light and variable over most of GoC. Image below is blended PW from CIRA at Colorado State valid at 1300 UTC (greens are over an inch and reds are over two inches). So, there is a very strong moisture gradient over the northern GoC and northwestern Sonora.
Second image below is current NHC forecast for track of Simon. The NHC forecasts Simon to eventually approach Baja as a remnant depression and then head into northwestern Sonora - somewhat similar to what it forecast for Odile last month.
The models continue to have a wide spread in their forecasts of where Simon's remnants will eventually track. To give a feel for this I show the NAM (above) and GFS (below) forecasts of 850 mb winds and heights, and also of PW. The forecasts are from 0000 UTC last evening and are both valid at 1200 UTC on Wednesday, October 8th. The NAM forecasts elongate Simon into a weak, inverted trough that extends just into southwestern Arizona. However, the GFS is more aggressive again and forecasts Simon's remnant circulation at 850 to move northeastward into Arizona, just south of Tucson. The NAM is somewhat similar to the ECMWF.
All models do forecast much increased PW into southern Arizona, as a weak, 500 mb trough approaches from the west. So, weather situation will be very complicated Tuesday through Thursday, with much depending upon how much moisture and instability develops over southern Arizona to interact with the trough. Not at all possible to forecast the details until Simon's demise process becomes more clear with time.
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