Look Ahead To The Weekend

First - high at TUS yesterday was 91 F, so the morning low here at house was 53 F cooler than the afternoon high - diurnal range of ~ 53 F. Low this morning was 41 F, but NWS forecast high today for TUS is 95 F.

This morning there is a cyclone spinning northeast of Hawaii (above is 15 UTC water vapor image) that is mostly out of the westerlies. However, models forecast that a southern stream will develop and pick up this feature during the next 36 to 48 hours. The MIMIC PW product from Univ. of Wisconsin, below for 13 UTC this morning, shows that there is a fair amount of PW associated with this system (25 to 35 mm). Further, a northward moving plume seems to be developing to the southeast of the cyclone, i.e., around 130 degrees W.

This morning's NAM forecast brings the weakening, 500 mb short wave across Arizona this weekend on Saturday and Saturday night (above 500 mb forecast is valid at 00 UTC on April 13th). The NAM forecast keeps this system very dry. The 850 mb forecast valid the same time, with forecast PW indicated, keeps PW values below 12.5 mm. So, much of what happens this weekend will depend upon exactly how the current PW field evolves with time. An interesting situation to keep an eye on.