4/26/2022

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Aspinall Operations Meeting

April 26, 2022

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April 2022

Weather Outlook

Aldis Strautins

National Weather Service

Grand Junction, CO

http://www.weather.gov/gjt

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April 2022 Outline

• Precipitation and Temperature

• Snow Water Equivalent

• Drought

• ENSO

• Weather outlook

April 2022 Sep – Nov, 2021 ‐ Precipitation

(percent of normal)

Dry fall for three quarters of the western slope going into the winter season

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April 2022 Water Year 2022 through mid April

Temperature

Departure from normal

Precipitation

% of normal

April 2022 Water Year 2022 through mid April

Temperature

Departure from normal

Precipitation

% of normal

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April 2022 Water year Precipitation (two stories)

Oct 1 – Dec 31, 2021

Dry Nov and early Dec / Very wet late Dec

Jan 1 – Apr 13, 2022

Below normal since Jan 1

April 2022 Water year Temperature (two stories)

Oct 1 – Dec 31, 2021

Dry Nov and early Dec / Very wet late Dec

Jan 1 – Apr 13, 2022

Below normal since Jan 1

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April 2022 April 2022

Temperature

Departure from normal

Precipitation

% of normal

April 2022 April 2022

Temperature

Departure from normal

Precipitation

% of normal

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April 2022 SNOTEL Snow Water Equivalent – NRCS

88% of Median

Yay...Late December Snow

Increased from 5in to over 10in

(SWE) (124% of Median)

Yay...Late February Snow

Ok...Some March and early

April Snow

Melt started in earnest last

week

Gunnison

April 2022 SNOTEL Snow Water Equivalent – NRCS

88% of Median as a

whole but there is a

different Story depending

were in the basin you

look

Gunnison

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April 2022 Drought

April 19, 2022 October 5, 2021 Drought Monitor (Colorado Basin View)

April 2022 Drought

April 19, 2022 April 20, 2021 Drought Monitor (SW View)

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April 2022 ENSO ‐ Outlook

Season La Niña Neutral El Niño

MAM 100 0 0

AMJ 89 11 0

MJJ 73 27 0

JJA 59 40 1

JAS 52 44 4

ASO 51 42 7

SON 53 39 8

OND 54 37 9

NDJ 53 37 10

CPC/IRI Early‐Month Consensus ENSO

Forecast Probabilities (using NWS CPC classification system)

La Nina this Spring – staying La Nina late this Summer into Fall

April 2022 ENSO 

North of Colorado – Dry and Warm

South of Colorado – Wet and Cool

North of Colorado – Wet and Cool

South of Colorado – Dry and Warm

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April 2022 WPC 7‐Day Precipitation Outlook

Accumulation period from Apr 28 ‐ May 3

April 2022 Outlook

May 1 ‐ 5 May 1 – 5

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April 2022 Outlook

May 3 – 9 May 3 – 9

April 2022 Monthly Outlook

Precipitation

May

Temperature

May

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April 2022 Seasonal Outlook

Precipitation

May/Jun/Jul

Temperature

May/Jun/Jul

April 2022 Seasonal Outlook

Precipitation

Jun/Jul/Aug

Temperature

Jun/Jul/Aug

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April 2022 Seasonal Outlook

Precipitation

Jul/Aug/Sep

Temperature

Jul/Aug/Sep

April 2022 Seasonal Outlooks

Precipitation                                                                                             Temperature

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Aspinall Operations Meeting

Water Supply Outlook

April 2022

Ashley Nielson

Senior Hydrologist

Colorado Basin River Forecast Center

National Weather Service/NOAA

Fall 2021 % Change: 2021-2020

Fall Modeled Soil Moisture Conditions: 2020 vs. 2021 

CBRFC Modeled Soil Moisture:

● Represents the deep soil layer

● Source of longer-term (weeks to years) streamflow 

● Impacts water supply forecasts

○ Below average conditions = lower forecasts

○ Above average conditions = higher forecasts

● Soil moisture conditions have improved from near record dry levels last year but still remain below normal 

across the majority of the Gunnison River Basin.

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Water Year (Oct-Mar) Precipitation

Basin Mean Precipitation as a % 

of Average 

Water Year 95

October 105

November 40

December 225

January 40

February 80

March 90

Water year precipitation is near normal in the 

Gunnison River Basin. There is a strong north-south 

divide with the northern half of the basin having better 

conditions that the southern half of the basin.

April Precipitation and Temperature to Date

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April 24, 2022 >11,000’: 113% 

9,500’-11,000’: 86%

● Impressive storms and significant SWE accumulation in late December

● Dry January; storms returned in Feb-April.

● Peak snow conditions:

○ Near to Above normal: Northern half of basin

○ Below normal: Southern half of basin

● Melt has begun below 11,000’; earlier than normal.

Snow Conditions: CBRFC Model Snow Water Equivalent

<9,500’: Nearly melted out

>11,000’: 76% 

9,500’-11,000’: 58%: 

<9,500’: Melted out

Taylor Park

96 kaf / 102%

East-Almont

170 kaf / 96%

Tomichi Ck

45 kaf / 67%

Lake Fork

83 kaf / 70%

Paonia

69 kaf / 85% Surface Ck

14.2 kaf / 

97%

Gunnison

Grand Junction

1020 kaf / 76%

Ridgway

67 kaf / 72%

Crystal

600 kaf / 78% Blue Mesa

526 kaf / 83%

April-July Volumes (kaf) / % of avg

Near to below average 

volumes expected.

Range: 70% - 102% 

of average

CBRFC April 25th Gunnison River Basin Water Supply Guidance

Forecast guidance has 

decreased since early April.

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90% chance of exceeding 440 KAF / 70% avg

10% chance of NOT exceeding 440 KAF / 70% avg

Blue Mesa Reservoir Inflow Forecast Plot Link

Water Supply Forecast Evolution: Blue Mesa Reservoir Inflow

50% chance of exceeding 526 KAF / 83% avg

50% chance of NOT exceeding 526 KAF / 83% avg

10% chance of exceeding 745 KAF / 117% avg

90% chance of NOT exceeding 745 KAF / 117% avg

Previous Years

2022 FCST: 526 kaf / 83% avg

2021 OBS: 317 kaf / 50% avg

2020 OBS: 387 kaf / 61% avg

2019 OBS:1090 kaf / 171% avg

2018 OBS: 239 kaf / 38% avg

Blue shading: Daily Raw Model Guidance 90% - 10% exceedance range

Blue line: Daily Raw Model Guidance 50% exceedance

Pink line: Official forecast 90%, 70%, 50%, 30%, 10% exceedance

Brown dotted: Average observed

Orange dashed: 2022 Observed Streamflow

Observed: 48 KAF (provisional)

10%

50%

90%

Average

Median

Blue Mesa Reservoir Inflow

April 1st Forecast 1991-2021

Mar 1st average error: 18% 

Apr 1st average error: 15% 

May 1st average error: 11% 

YEAR

APR 1 FCST 

(KAF)

OBSERVED 

(KAF) Error KAF / %

2010 560 494 66 / 14%: over

2001 550 506 44 / 8%: over

2022 530 ? ?

2020 525 387 138 / 36%:over

2016 515 602 87 / 14%: under

Historical Forecast Errors with similar April 1 Forecasts

Forecast Performance

Over forecast

Under forecast

Primary Sources of Forecast Error:

● Future Weather

○ Uncertainty in precipitation and temperature 

forecasts

○ Extreme dry/wet events results in larger errors

■ Rarely forecast in advance

● Model States: Is the model representative of reality?

○ Snow

■ SNOTELs and Satellite images used to verify 

○ Soil moisture

■ Extensive analysis done in Fall

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Upcoming Weather

Precipitation Forecast: 4/26-5/3 Temperature Anomaly: Wednesday 4/27

Temperature Anomaly: Friday 4/29

• Soil moisture

• Conditions have improved from last year but are still below normal.

• Soil moisture deficits still exist and must be overcome before runoff can occur.

• Snow

• Peak Snow:

■ Near to above normal: Northern half of basin

■ Below normal: Southern half of basin

• Melt at elevations below 11,000’

• Melt earlier than normal

• April Water Supply Forecasts

• Near to below average

■ Impacted by below normal modeled soil moisture conditions

• Forecast guidance has decreased since early April for the majority of the basin.

• Upcoming Weather

• Minimal precipitation expected in the Gunnison River basin over the next week.

■ April precipitation will most likely end below normal.

• Periods of above average and below average temperatures

Summary

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CBRFC Webpage

https://www.cbrfc.noaa.gov/

CBRFC Operations

cbrfc.operations@noaa.gov

801-524-4004

CBRFC Water Supply Presentations

https://www.cbrfc.noaa.gov/present/present.php

Basin Forecasters

Brenda Alcorn - Green, Duchesne, White/Yampa

brenda.alcorn@noaa.gov

Ashley Nielson – Gunnison, San Juan, Dolores, Lake Powell

ashley.nielson@noaa.gov

Cody Moser – Upper Colorado Mainstem

cody.moser@noaa.gov

Patrick Kormos – Great Basin/Sevier

patrick.kormos@noaa.gov

Trevor Grout - Virgin, Lower Colorado

trevor.grout@noaa.gov

Brent Bernard – Hydrologist

brent.bernard@noaa.gov

Tracy Cox - Hydrometeorologist

tracy.cox@noaa.gov

Nanette Hosenfeld - Senior Hydrometeorologist

nanette.hosenfeld@noaa.gov

Wolfgang Hanft - Hydrometeorologist

wolfgang.hanft@noaa.gov

Michelle Stokes – Hydrologist In Charge

michelle.stokes@noaa.gov

Paul Miller– Service Coordination Hydrologist

paul.miller@noaa.gov

John Lhotak – Development and Operations Hydrologist

john.lhotak@noaa.gov

801-524-5130 x 333

CBRFC Contacts

SNOWPACK SUMMARY

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79%

82%

69%

69%

227%

61%

105%

101% of seasonal peak

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104% of seasonal peak

RESERVOIR AND RIVER STATUS

Blue Mesa Reservoir content is currently at 243,000 acre‐feet at an elevation

of 7437 feet.

Crystal Dam is releasing 500 cfs and flows in the Gunnison River through the

Black Canyon are 350 cfs

Flows in the lower Gunnison River at the Whitewater gage are 2100 cfs, above

the baseflow target of 890 cfs

The Gunnison Tunnel has been shutdown due to an erosion issue near the

South Canal. Crystal releases have been reduced accordingly and river flows

downstream are around 350 cfs.

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SPRING RUNOFF 

FORECASTS AND TARGETS

Early season runoff forecasts for major rivers in the Gunnison Basin are in the

70‐100% of average range

The April 15th runoff forecast for Blue Mesa Reservoir puts 2022 into the

Moderately Dry hydrologic category

The ROD targets in the Moderately Dry category call for a 1 day peak flow of

7,624 cfs at Whitewater. However, there is a drought rule that allows the peak

flow at Whitewater to be reduced to 5,000 cfs when Blue Mesa content is less

than 400,000 acre‐feet.

There are no half bankfull or peak flow duration targets.

Drought rules that lower the baseflow targets will be in effect in a Moderately

Dry year

The Black Canyon water right peak flow target is 2,790 cfs

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Year Type Blue Mesa Forecasted Desired Peak at

Whitewater

Duration of Half Bank

(8,070 cfs)

Duration of Peak Flow

(up to 14,350 cfs)

April‐July Inflow

Af cfs Days Days

DRY < 381,000 900 0 0

MOD DRY 381,000 to 516,000 2,600 to 8,070 0 0

AVG DRY 516,001 to 709,000 8,070 10 0

AVG WET 709,001 to 831,000 8,070 to 14,350 20 2

MOD WET 831,001 to 1,123,000 14,350 40 10

WET >1,123,000 14,350 60 15

Spring Peak & Duration Targets

Based on Hydrologic Year Type

April 15

505,000

Drought Rules

 When a Moderately Dry year follows a Dry or Moderately

Dry year and Blue Mesa content < 400,000 af on Mar 31 or

Apr 30, the peak target at Whitewater is reduced to 5000 cfs

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2790 cfs

Apr 15 Forecast

505 KAF

Shoulder Flows

May 1 – July 25

300 cfs

3045 cfs * .9164 = 2790 cfs Drought Recovery Provision in Effect

1. Avg Dry/Mod Dry/Dry year following a Dry year

2. BM content < 550 Kaf on Dec 31

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PROJECTED OPERATIONS

In order to achieve the ROD targets in the lower Gunnison River it is expected

that flows in the Gunnison River through the Black Canyon will peak near

2,800 cfs

The entire spring operation is projected to take 11 days

Blue Mesa Reservoir is expected to reach a maximum content of ~450,000

acre‐feet, about 47 feet below the full reservoir level

A change back to the Average Dry category would result in lower reservoir

levels at Blue Mesa than the current Mod Dry category projections

After the spring operation has concluded, Aspinall releases will continue to

meet the baseflow targets

Flows in the Gunnison River through the Black Canyon are projected to range

between 300 cfs and 400 cfs during the summer and fall months

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North Fork of the Gunnison River

Forecasted Streamflows

Peak Flow

Forecast

2900 cfs

Projection of Flows in the Gunnison River

while meeting the Aspinall ROD Flow Targets

Mod Dry – 505 Kaf Runoff

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Avg Dry – 530 Kaf Runoff

OPERATIONS – REMAINDER OF YEAR

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Drought Rules

 During Dry and Moderately Dry years, if Blue Mesa Reservoir content

drops below 600,000 af, the Whitewater baseflow target is reduced from

1050 cfs to 900 cfs until Blue Mesa Reservoir content exceeds 600,000 af

Baseflow Targets

Mod Dry – 505 Kaf Runoff

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Avg Dry – 530 Kaf Runoff

Drought Response Operations 

Agreement

(DROA)

Update for April 2022

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H.  Outreach Summary

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0 ‐ ‐

•Documents published to 

https://www.usbr.gov/dcp/droa.html

•Upper Colorado River Commission considered 

during special session April 21 and recommends 

sending to Secretary of the Interior for approval

Currently there is no planned DROA Release at 

Aspinall in WY 2022. 

Timeline

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See more about Glen Canyon Operations here: https://www.usbr.gov/uc/water/crsp/cs/gcd.html

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Questions?

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Special Flow Requests and Discussion – All

Reports of Agencies and Organizations – All

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Reclamation Contacts:

Ryan Christianson:  970‐248‐0652  rchristainson@usbr.gov

Erik Knight:        970‐248‐0629  eknight@usbr.gov

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