Old Fashioned Major Rocky Mountain Storm

30 January 2014 By In Blog style

MAJOR Old fashioned Rocky Mountain Snow Storm 30-31 Jan 2014

A typical Rocky Mountian snowstorm was triggered by the subtropical jet stream from Hawaii to Oregon and California and down into Colorado which was well predicted by numerical models and NOAA and local forecasters.  This jet was clearly seen in the water vapor imagery shown in Figure 2 from the NOAA Eastern Pacific satellite imagery at 1530 UTC on Jan 30, 2014.  It produced over 15 inches of new snow at my home in Summit County, CO at 9684 ft msl (2952 m msl) between 0200 and 0700 MST. Figure 1 shows a typical photo on our deck at 0700.  The total by 1600 MST today reached 21 inches with S to S+ continuing and over 0.80 inches of snow water equivalent.  Snow depths at standard snow poles are approaching 48 inches (122 cm) now.  Day 2 of storm produced another 14.5 inches and 0.99 inches of snow water equivalent for a total of 27.5 and 1.64 inches of water.  The snow continues to fall lightly in the strong SW flow into the 3rd day 1 Feb 2014. 

Figure 1.  Photo of deep snow on our deck.

Figure 2. Water Vapor satellite imagery over eastern Pacific Jan 30, 2014 1200 UTC from NOAA.

imagery showing the subtropical jetstream extending from Hawaii NE to California bringing beneficial snows and rains to California and the Sierra, and heavy snows to Colorado.

The US Navy NOGAPS Model among others predicted the cutoff of the Pacific Coast ridge which had kept California in drought and warm temperatures all winter.  Figure 3 shows this initial model analysis and Figure 4 shows the 72 hour prediction of the major jet impacting the west coast and into Colorado at the 300 mb jet stream level (9300 m msl).  Note the strong “polar vortex” again over E North America that brought bone chilling cold to the East.


Figure 3.  NOGAPS US Navy model analysis of the 300 mb level jet stream pattern on 27 jan 2014 at 1200 UTC.  This is the initial stage of the Pacific Ridge breaking down and allowing Pacific moisture flux into California and across the Rockies.




Figure 4.  Same as 3 with 72 hour prediction for 30 Jan 2014.

The NOAA National Centers for Environmental Prediction NCEP’s Hydrological Prediction Center HPC made a 48 hour total precipitation forecast for 30 Jan -1 Feb 2014 3 days ahead that predicted a major storm over Colorado’s Rockies.  Figure 5 shows this forecast for a maximum of 1.82 inches, and 1.36 over the central Sierra Nevada in California.


Figure 5.  Quantitative Precipitation Forecast QPF by WPC for 30 Jan-1 Feb 2014.

The moisture flux over the mountain barriers is the key to significant precipitation.  Moisture flow at the 700 mb level (3000 m msl) provides an excellent indicator of precipitation potential. The models also predicted this quite well as shown in figures 6-7 for the NOGAPS model.


Figure 6.  NOGAPS 700 mb flow with vertical motion and relative humidity fields in the 36 hour forecast for 0000 UTC Jan 31, 2014.  This forecast verified well on Friday 30 Jan 2014 shown in fig. 7.




Fig 7. NOGAPS 700 mb flow in the 12 hour forecast for 31 Jan 2014 at 0000 UTC.  this shows the strong continuing moisture flux across Colorado.

 RADAR for the US and Colorado clearly showed the beneficial precipitation from this storm from California to Colorado.  The NCAR RAP Real-Time Weather web site provides an excellent summary of RADARS across the country.  At 2300 UTC on Jan 30, 2014 we see  the intense snowfall over Colorado on the country-wide site (Fig 8) and the Colorado regional reflectivity data (Fig 9). 



Figure 8. Radar across the US at 2300 UTC Jan 30, 2014.



Figure 9. Radar from regional radars in Colorado at 2300 UTC Jan 30, 2014.




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