Sunday, September 7, 2014

Major Monsoon Surge Underway

You can say "yeah, but it's a dry heat" all you want today, but the reality is that it will be quite humid (by local standards) in many parts of the desert southwest today and tomorrow.

This morning (1500 UTC/0900 MDT), the decaying circulation of former Hurricane Norbert (now Tropical Storm Norbert) sit off the Baja coast.  A major slug of moisture (integrated precipitable water contours below illustrate the total water vapor in the atmosphere) to Norbert's northeast is now pushing into the lower Colorado River Basin and the surrounding region.

The corresponding higher-resolution 3-hour forecast of integrated precipitable water and surface wind from the NAM shows the complex stew of water vapor that will be influencing the southwest the next couple of days.  Yeah, integrated precipitable water values are high around Norbert, but there is also a related surge of Gulf of California moisture into the lower Colorado River Valley and moisture originating to the east near the Gulf of Mexico flowing westward as well.  

Current dewpoints over the southwest are not totally outrageous, but are enough to make you sweat.  How about 67ºF in San Diego, 76ºF at Imperial County Airport, 69ºF at Fort Yuma, 63ºF in Boulder City, and up to 67ºF in the Phoenix metro area.  

Source: MesoWest
The NAM forecast loop below shows the impressive push of moisture today and tomorrow from the Gulf of California up the lower Colorado River basin into southern Nevada and Utah.  Along the Wasatch Front, we have a chance of thunderstorms through the period.  I watered my lawn yesterday, so that ensures a good deluge.  

Flash flood watches have been issued by the NWS for much of the region experiencing the surge (green fill below).  
Source: NWS
And, in case you are wondering from previous, there will be no hurricane for San Diego.  Looks like after substantial weakening, the upper-level remnants of Norbert will track across northern Baja on Tuesday and Wednesday (It's unclear if the circulation center at the surface will ever move onshore).  Mother Nature will not go Beatrice Prior and choose the GFS solution.  

No comments:

Post a Comment