This will be the last of the preliminary snowpack reports from Niwot C1,
as the official long term data period, and regular reports, begin
at the end of December.

It has been interesting to watch the excellent start to this years'
snowpack, early and strong over the entire state, after the past water
years' drought.
As of November 30th, the high early snowpack percentages are returning to average
in most places, or below in the case of southern Colorado.
The high values remained quite high into the middle of November, but
the the past two weeks tended to be dry, if not dry and warm in the case
of southern Colorado, and this depleted the snowpack.
In mid-November, the Upper Rio Grande and the San Miguel, Dolores, San Juan
basins were 131% and 147% of average (1971-2000), but two weeks later
they were 80% and 94%, respectively.
Northern basins have also declined, but not as much.
The Upper Rio Grande is 126% (highest in the state), and the South Platte
is 103%, down from 140% and 108% on Nov. 1, respectively.

At Niwot (C1), on 30 November 2002, the snowpack was 106% (225% on Nov.1),
amounting to 3.3 inches snow water equivalent (SWE), and 14 inches deep.
It recieved a total of 31.9" of snowfall, 2.61" SWE in November (average
density of 8%), and the SWE:precipitation ratio shifted from positive
to negative since the first of the month (loosely interpreted as 'it got
warmer&/or drier than average').

This same ratio shift has occurred throughout the state, in general.

What might we expect for the rest of the winter?
A recovery to average or above average conditions in the south,
based on the convential wisdom that El Nino years benefit that
region.
However, if  the linked phase mechanism described
by Gershunov & Barnett (1998, BAMS) applies, the classic
El Nino pattern, wetter in the southwestern US (including
southern Colorado), may be weak and confused, resulting in little
El Nino effect.

In conclusion, the excellent start to this snowpack year is still
good, but has slipped a bit in the last two weeks; partially
as the season gains a more representaive statistical base, but
also due to unsupportive weather conditions.
Classic El Nino patterns hold promise for southern Colorado to
return to normal, or above, conditions, but the PDO/ENSO phases
may be out of synchrony (if the PDO phase has switched,
as many believe), thus weakening the classic El Nino
pattern of heavier snows of southern Colorado.

Cheers!
Mark Losleben

Sno Tel Data  Niwot Ridge, C-1
Snow Water Content (inches)
Values are for the end of given month
except as noted for May and June