1706374 1-877-929-0660 hydrologist ing er river

Colorado B

asin River

Forecast Center

Water S

upply Briefing

Great B

asin, Duchesne, Virgin

May 7

th, 2019

Patrick K

ormos - H

ydrologistG

reg Sm

ith - Sr. H

ydrologistB

renda Alcorn - S

r. Hydrologist

Ashley N

ielson - Sr. H

ydrologistB

rent Bernard - H

ydrologist

Please mute your phone

until ready to ask questions

CB

RFC

Forecast Areas

Phone: 1-877-929-0660

Passcode: 1706374

Virgin Sevier

Duchesne

Six C

reeks

Provo

Bear

Weber

Today’s Presentation

●W

eather review

○A

pril Precipitation

●C

urrent Snow

pack

●A

pril Stream

flow Volum

es

●M

ay 1 Water S

upply Forecasts

●M

ay Forecast Error

●U

pcoming W

eather

●C

ontacts & Q

uestions

* Please mute your phone until the question period *

Phone: 1-877-929-0660 Passcode: 1706374

April Precipitation Pattern

April 2019 Total Precipitation - Measurem

ents

April SNO

TEL Precipitation Percent of N

ormal.

●M

ost 125% to 150%

Virgin135%

Sevier135%

Provo120%

Duchesne

120%

Bear140%

Six Cks130%

Weber

125%

Bear115%

Six Cks130%

Provo135%

Sevier140%

Virgin150%

Weber

125%

April 2019 Total Precipitation - CBRFC Basins

April was 120%

and up in the G

reat Basin.

April Temperature Pattern

Current Snowpack - M

ay 6 Snow Conditions

Many areas still

above 150% of

median

Some of the highest

percent of medians

are in lower elevation

and/or southern areas

SNO

TEL SWE (%

Median)



Current snow conditions in percent of

normal.

●D

ependant on melt out pattern

●D

ependant on the ‘normal’

●M

onthly precipitation and actual SW

E values may provide a better

basin indicators

SNO

TEL SWE (%

Median)



SNO

TEL SWE (%

Median)

Current snow conditions in percent of

normal.

●Sm

ith and Morehouse has 7.7”

swe

●M

edian is 2.8”●

275% of norm

al

April Streamflow

Volume O

bservations

Basin Mean

Percent of Norm

al

Bear 110%

Weber

115%Six Creeks

110%Provo

160%

Sevier140%

Duchesne

130%

Virgin190%

Water S

upply Forecasts – Great B

asin/Utah

May 2019 W

ater Supply Forecasts

●M

ay 1 Forecast for April-July Volum

e in 1000’s acre feet (K

AF)

●

Includes April O

bserved Stream

flow

●P

ercent of 1981-2010 average

●M

any Forecasts have increased from

April 1

Water S

upply Forecasts – Great B

asin/Utah

Changes from

April to M

ay

●M

ay 1 Forecast for April-July Volum

e in 1000’s acre feet (K

AF)

●

Includes April O

bserved Stream

flow

●P

ercent of 1981-2010 average

●M

any Forecasts have increased from

April 1

May 1

st Water S

upply Forecasts – Bear R

iver Basin

116%

117%

++

125%

150%

113%++

85%

88%

Bear

Stateline

Logan River

Blacksm

iths Fork

Little Bear

Sm

iths Fork

April-July

Forecast S

treamflow

Volumes

(% of 1981-2010 average)

Stew

art Dam

Bear

Above W

oodruff N

arrows

Median

Basin

Forecast:

Jan - 70%Feb - 85%M

ar - 95%A

pr - 100%M

ay - 115%

Increases from 0%

to 20% in volum

eForecast range: ~85%

-150% of average

+

Forecast Evolution P

lotLogan R

iver: 125 KA

F / 113% Avg

20% increase in volum

e from April 1 to M

ay 1 Forecast

Jan 1

Feb 1

Mar 1

May 1

Apr 1Average Stream

flow /

Volume O

bservations

2019 Measured Volum

e to date

Decreasing Exceedance

Ranges


lotS

miths Fork: 76 kaf / 85%

Same O

fficial 50 Forecast for May as April and M

arch. Confidence has increased.

May 1

st Water S

upply Forecasts – Weber R

iver Basin

114%

157%

163%150%

136%148%

125%

114%118%

123%

Weber-O

akley

Chalk C

reek

Weber-G

ateway

East C

anyon Inflow

Pineview

Inflow

Lost Creek

InflowRockportInflow

April-July Forecast

Stream

flow Volum

es

Weber

Coalville

South ForkO

gden

Echo

Median

Basin

Forecast:

Jan - 75%Feb - 85%M

ar - 105%A

pr - 120%M

ay - 130%

Increases from 0%

to 25% of volum

eForecast range: ~114%

-163% of average

+

++

+


lotLost C

reek: 20 kaf / 149%


e from April 1 to M

ay 1 forecast.

May 1

st Water S

upply Forecasts – Six C

reeks

110%

Little C

ottonwood

April-July

Forecast S

treamflow

Volumes

(% of 1981-2010 average)

125%125%

107%

134%

128%

106%

120%

130%

Big

Cottonw

ood

Mill C

reek

Lambs

Creek

Little Dell

Inflow

Parleys

Creek

Em

igrationRed Butte

City C

reek

Median

Basin

Forecast:

Jan - 65%Feb - 90%M

ar - 115%A

pr - 125%M

ay- 125%

Change of -17%

to 20% of volum

eForecast range: 107%

-134% of average -

+


lotLittle C

ottonwood: 49 kaf / 129%

Average


e from April 1 to M

ay 1 forecast

May 1

st Water S

upply Forecasts – Provo R

iver/Utah Lake

123%P

rovoW

oodland

158%

138%

139%

155%

138%

Deer C

reekInflow

Spanish Fork

Am

erican Fork

Provo

Hailstone

West C

anyonC

reek

Utah LakeInflow

Median

Basin

Forecast:

Jan - 70%Feb - 100%M

ar - 125%A

pr - 135%M

ay- 145%

Increases from 0%

to 25% of volum

eForecast range: 123%

-158% of average

+

++

+

156%


lotP

rovo Woodland: 123 kaf / 123%

of average

Same forecast on April 1 as M

ay 1 forecast.


lotU

tah Lake: 505 kaf / 155% of average


e from April 1 to M

ay 1 forecast

May 1

st Water S

upply Forecasts – Duchesne

95%

Red Fleet

143%173%

DuchesneM

yton

Whiterocks

Starvation

Median

Basin

Forecast:

Jan - 75%Feb - 100%M

ar - 115%A

pr - 120%M

ay- 125%

102%

Ashley

Creek100%

127%

Uinta

Neola

Yellowstone

126%

129%

124%

Moon

Lake

Upper

Stillwater

126%

DuchesneTabiona

Straw

berry128%

Duchesne

Randlett

138%

Increases from 0 to 10%

of volume

Forecast range: 95%-173%

April-July

Forecast


lotS

trawberry: 105 kaf / 148%

of average


e from April 1 to M

ay 1 forecast

May 1

st Water S

upply Forecasts – Sevier/Virgin

144%

Sevier-

Gunnison

153%

157%Virgin-Virgin

Median

Basin

Forecast:

Sevier:

Jan - 60%Feb - 90%M

ar - 130%A

pr - 135%

Virgin:Jan - 50%Feb - 80%M

ar - 110%A

pr - 115%

249%

Clear

Creek

EF S

evier-K

ingston

149%Sevier-H

atchVirgin-

Hurricane

133%

Virgin-Littlefield

151%

Forecast range: 114% to 250%

Changes from

-10% to 45%

of volume

Sevier:

Virgin:

Increased 21% to 58%

of volume

Forecast range: 133% to 100%

of volume

April-July

Forecast S

treamflow

Volumes

(% of 1981-2010 average)


lotS

evier Hatch: 73 kaf / 152%

of average


e from April 1 to M

ay 1 forecast


lotVirgin at Virgin: 91 kaf / 157%


e from April 1 to M

ay 1 forecast - increase model snow

NF of the Virgin

% Forecast E

rrorA

pril to May

April-July Volum

e

Logan A

pr 14% - M

ay 12%Provo W

oodland A

pr 13% - M

ay 13%Little C

ottonwood:

Apr 14%

- May 11%

Little Bear R

iverA

pr 23% - M

ay 21%Weber O

akley A

pr 14% - M

ay 11%

Bear R

iver UT-W

YA

pr 15% - M

ay 13%

Forecast Validation: Historical m

odel error March to A

pril

Sm

all improvem

ents between A

pril and May 1st Forecast

Errors (2-3%

)

Forecasts are better than just going with average

Where W

e Do B

etter:H

eadwaters

Prim

arily snow m

elt basinsK

nown diversions / dem

ands

Where W

e Do W

orse:Low

er elevations (rain or early melt)

Dow

nstream of diversions / irrigation

Little is known about diversions / dem

ands

Historical M

odel Error

1981-2010

Map is available at:

https://ww

w.cbrfc.noaa.gov/arc/verif/verif.php

From W

ater Supply drop dow

n menu

→ select H

istorical Verification Map

Historical W

ater Supply Verification - May

East C

anyon Creek

Apr 26%

- May 25%

Upcom

ing Weather S

umm

ary - Satellite from

this morning

Low

Pressure Circulation

Low pressure system

moving through the area increase in cloud cover and instability

Upcom

ing Weather S

umm

ary - Model

Tonight May 7th

Low pressure m

oves east. Trough drops from the north. Increasing instability resulting in show

ers and thundershow

ers. Temperatures below

normal. Snow

levels down to 8000-9000 feet.

Upcom

ing Weather S

umm

ary - Blocking P

attern

Friday April 10 L H

Low pressure system

moves east off the w

est coast. High pressure to the north. Low

pressure has little east-w

est movem

ent. This pattern feeds moisture into the forecast area. O

ccasional showers and below

norm

al temperatures.

Upcom

ing Weather S

umm

ary - 5 day Precipitation Forecast

●M

ost precipitaiton in the next 72 hours.

●Larger am

ounts central U

tah

●W

idespread 1-2 inch precipitation am

ounts possible

Upcom

ing Weather S

umm

ary - Blocking P

attern

Low is still here

Monday April 13

Models still have the low

pressure dominating the pattern over the forecast area. Low

may m

ove eastward

during the week. W

armer and dryer w

eather may follow

. The timing of eastw

ard movem

ent will affect

snowm

elt.

Upcom

ing Weather S

umm

ary - Warm

er Temps. next w

eek.

Warm

er Tem

peratures

Thursday May 16

High pressure and above norm

al temperatures develop next w

eek. How

long will this pattern persist? N

ext storm

will increase cloud cover &

showers. The tim

ing of eastward m

ovement w

ill affect snowm

elt.Cooler, w

et weather for the 18th -19th w

eekend.

Upcom

ing Weather S

umm

ary - Longer Range W

eather

Pattern remains progressive / active approaching M

emorial D

ay weekend.

Pattern is trending wetter w

ith periods of below and above average tem

peratures.

This weather pattern m

akes peak flow forecasts difficult.

May 14-20

May 14-20

2019 Water Supply Briefing Schedule

2019 monthly w

ater supply briefings for the Great B

asin/Utah

Additional w

ebinar will be scheduled for early June if needed.

Date/Tim

es are subject to change.

All registration inform

ation has been posted to the CB

RFC

w

eb page.

Thank you for attending.

CBRFC Water Supply Contacts

Michelle S

tokes – Hydrologist In C

hargem

[email protected]

Paul M

iller– Service C

oordination Hydrologist

paul.miller@

noaa.gov

Basin Focal P

oints (Forecasters)B

rent Bernard – S

ix Creeks, P

rovo , Sevier Focal P

ointbrent.bernard@

noaa.gov

Patrick K

ormos – B

ear, Weber Focal P

ointpatrick.korm

[email protected]

Greg S

mith – S

an Juan, Gunnison, D

olores Focal Point

greg.smith@

noaa.gov

Ashley N

ielson – Green R

iver Basin, Lake P

owell Focal P

ointashley.nielson@

noaa.gov

Cody M

oser – Upper C

olorado Mainstem

Focal Point

cody.moser@

noaa.gov

Tracy Cox and Zach Finch – Low

er Colorado B

asin, Virgin Focal Point

[email protected]

[email protected]

Please contact us w

ith any questions

Current Peak Flow Flood Probability

●City Creek and D

uchesne Randlett have forecast m

ean daily peaks close to flood stage between

10 and 25% level.

●In addition, Chalk Creek has an instantaneous forecast peak greater than 30%

chance of reaching bankfull

●Com

bination of high elevation snowpack levels and

continued delayed melt could increase flood

potential

●Prolonged spring w

arm-up or rain events can cause

flooding issues in any year

1706374 1-877-929-0660 hydrologist ing er river

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