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NOAK48 PAFC 171012

Public Information Statement
National Weather Service Anchorage AK
212 AM AKDT Fri Mar 17 2017

...Datum and flood threshold changes on several streams and
rivers around Southcentral Alaska...

On or around April 17 2017 the National Weather Service (NWS)
Forecast Office in Anchorage Alaska and the Alaska-Pacific River
Forecast Center (APRFC) will be adding or modifying the existing
flood thresholds at several area rivers.

Of particular note, the flood thresholds at the river gage on the
Matanuska River near Palmer will be changing from a stage (water
level height)-based threshold to a discharge (amount of water
flowing through the river)-based threshold. For more information
please visit:

A summary of all changes is found below:

Flood Category Old Value New Value

Lowe River above Horsetail Falls near Valdez (Site: LHFA2)
Action Stage None 11.0 FT
Minor Flood None 14.0 FT
Moderate Flood None 15.0 FT

Solomon Gulch Creek near Valdez (Site: SGLA2)
Action Stage 8.0 FT 16.0 FT
Minor Flood 8.5 FT 16.5 FT
Moderate Flood 9.0 FT 17.0 FT

Yentna River near Lake Creek (Site:YLKA2)
Action Stage 19.0 FT Unchanged
Minor Flood 20.5 FT Unchanged
Moderate Flood 21.5 FT 22.0 FT
Major Flood 23.0 FT 24.0 FT

Iliamna River near Pedro Bay (Site: ILRA2)
Action Stage 71.0 FT 64.0 FT
Minor Flood 72.5 FT 71.0 FT
Moderate Flood 75.0 FT Unchanged

Matanuska River near Palmer (Site: MATA2)
Action Stage 9.0 FT 15,000 CFS flow
Minor Flood 9.5 FT 30,000 CFS flow
Moderate Flood 10.8 FT 35,000 CFS flow

These new and revised flood stages will be referenced in flood
warnings, flood statements, and flood advisories. These changes
are part of a recent re-evaluation of flooding impacts at these
locations which included coordination with local emergency

In addition, on or around April 17 2017 the published datum for
several sites will be changing to match the datum used by the
United States Geological Survey (USGS - who owns and maintains
these gages). The water levels reported by these gages will NOT
change, and flood stages will NOT change unless noted above. This
change simply brings NWS into full agreement with the official
USGS information.

Site Old Datum New Datum
CHRA2 - Chester Creek 16.00 (NGVD29) 16.02 (NGVD29)
KNKA2 - Knik River 30.20 (NGVD29) 33.57 (NAVD88)
MATA2 - Matanuska River 170.90 (NGVD29) 185.24 (NAVD88)
MONA2 - Montana Creek 245.00 (NGVD29) 250.00 (NAVD88)
SXRA2 - Kenai River 35.34 (NGVD29) 40.40 (NAVD88)

Comments and questions about these changes should be directed to:

Andrew Dixon
Senior Service Hydrologist
NWS Anchorage
Andrew.Dixon at NOAA.GOV




NOAK47 PAJK 230720

Public Information Statement
National Weather Service Juneau AK
1120 PM AKDT Wed Mar 22 2017


On Wednesday, March 29th at approximately 10:15am, the National
Weather Service, Alaska Division of Homeland Security and
Emergency Management, and the Alaska Broadcasters Association will
conduct a test of the Alaska tsunami warning system as a part of
tsunami preparedness week in Alaska. The test will be broadcast on
radio and television stations and the broadcast will state that it
is only a test. Some communities may activate their sirens. NOAA
all hazards weather radio listeners will hear a tone alert
followed by a test message. After the test, we invite you to
provide feedback on line at READY. DOT. ALASKA. DOT. GOV. Once
again, a tsunami warning system test will be conducted on
Wednesday, March 29th at approximately 10:15am Alaska Daylight
Time. The test will be cancelled in the event of any significant
seismic activity.