FLOOD06496

• County: Eagle
• Community: Vail, Eagle County
• Stream Name: Gore Creek
• Basin: Colorado Mainstem
• Title: Floodplain Information Report
• Date: 6/1/1975
• Prepared For: Eagle County
• Prepared By: HYDRO-TRIAD, LTD.
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

-11-

~
"
I
I
i
,
,
.i .
I
I
I
,
I
i

Moisture Sources
There are three moisture sources available to the Gore Range.1,l,3,4
Each of these sources is associated with a different season of the year.

Figure 111-1 illustrates the flow of air from these seasonal moisture

sources.

Winter and spring snows, which form the bulk of the annual precipi-
tation are a result of moist air masses originating in the cool Northern
Pacific Ocean in the Gulf of Alaska and moving inland from the Pacific

Northwest. These air masses must pass over the Cascade Range or the
Sierra-Nevada Range, several ranges in Nevada, Idaho and Utah and then
a series of ranges in the Colorado Rockies before arriving at the Gore
Range. The series of uplifts during transit causes much of the moisture
to precipitate out, thereby limiting the amount of moisture available

for delivery to the Gore Range.
Summer showers and thunderstorms, with moisture pulled in from
the Gulf of Mexico, occur most commonly in July and August, although
thunderstorms can occur as early as May and as late as October. Tempera-
tures in the Gore Creek Valley are usually too cold in May and June to
provide the uplift necessary to produce significant thunderstorms and
the showers that occur in the early months generally serve only to

increase the snow pack moisture content.
During the early fall (September and early October), there are
occasional general rainstorms caused by dying major Pacific storms.

,
.

These wa~~ air masses, heavily loaded with moisture, move in fr~~ the

,

San uiego area, passing through Calitornia, across Arlzona ana lnto

>

, I
. I
. I
41

.

-12-

southwestern Colorado. After passing over numerous mountain barriers,
the moisture content is normally depleted by the time the air mass
reaches the Gore Creek basin.
Rainfall Precipitation
Rainfall in the Gore Creek Valley can be either the more common
thunderstorm or the infrequent general type storm.
The thunderstorms occur most frequently and with greatest in-

tensity in July and August. These storms deliver the majority of
their precipitation in a time span of about 25 minutes.7 Amounts of
precipitation generated from these storms in the Gore Creek basin are
somewhat smaller and the intensity is less than those occurring at
lower elevations due to the lesser amount of moisture available at
the lower temperatures, higher elevations and the protection of the
area from available moisture sources.
Detailed examination of the available records for an indication

of rainfall induced snowmelt produced little indication of this phe-
nomena being critical in the hiqher levels of the Central Rockies.

This is attributed to the fact that temperatures in May and early
June in the Gore Valley are normally too cold to provide enough

uplift for a thunderstorm. For the cases where precipitation occur-
red in the form of snow or sleet at higher elevations and rain at
the lower, the results were to increase the snowpack depth in the
high elevations and the snowpack water content in the lower elevations.
The records show that the streamflow discharge usually drops signifi-
cantly on days with precipitation Decause the associated temperature
drop reduces the snow melting.