Flooding in Alaska, October 1, 2004

Name: Flooding in Alaska, October 1, 2004
Start: 2004-10-01T00:00
End: 2004-10-01T16:00
Location: Alaska

October 1, 2004 · NWS AFC · 2 events in 2 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 2

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS AFC wrote it up.

A strong Bering Sea storm pushed extremely moist air into the south central region of Alaska beginning Wednesday, September 29th. Heavy rain and snow occurred over the previous weekend resulting in saturated soil throughout the region. Rainfall of moderate to heavy rates was reported by observation sites in the Susitna Valley south to the Anchorage bowl beginning late Wednesday, September 29th, through late Thursday, September 30th. Amounts of 2 to 3 inches were observed across this region with higher estimated amounts along the Chugach and Talkeetna Mountains. This resulted in the small streams in the Anchorage Bowl and in the central Susitna Valley, which were already elevated from the weekend storm, to rise above bank full stage and cause minor flooding.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Anchorage, AK wrote its last area forecast discussion before the first event at Sep 30, 11:30 AM AST, 12 hours 30 minutes earlier.

Area forecast discussion, Sep 30, 11:30 AM AST, 12 hours 30 minutes before

AREA FORECAST DISCUSSION SOUTHCENTRAL ALASKA
1230 PM ADT THU SEP 30 2004

.DISCUSSION...

.ANALYSIS...WATER VAPOR IMAGERY SHOWS MAJOR UPPER CLOSED LOW CENTERED
AT 47N 167W WITH TROUGH EXTENDING NNE TO ANOTHER LOW AT 64.5N 159W.
HIGH AMPLITUDE LONG-WAVE RIDGE LOCATED OVER THE EAST PACIFIC. LONG
FETCH MOISTURE TRANSPORT CONTINUES FROM BOTTOM OF TROUGH AROUND 40N
TO TOP OF RIDGE NEAR 70N. SURFACE LOWS AND CONNECTING COLD FRONT
LOCATED 100 TO 200 NM EAST OF UPPER REFLECTION. STEADY PRECIPITATION
CONTINUES FROM AKPENN NORTHEASTWARD TO MOST OF SOUTH CENTRAL ALASKA.
PRECIPITATION IS ALL RAIN WITH THE EXCEPTION OF NORTHERN SUSITNA
VALLEY WHERE HEAVY SNOW HAS BEEN FALLING SINCE WEDNESDAY NIGHT.
BETWEEN 10 PM LAST NIGHT TO 9 AM THIS MORNING CHULITNA RECEIVED
APPROXIMATELY ONE FOOT OF SNOW. ISSUED A HEAVY SNOW WARNING THROUGH
THIS AFTERNOON FOR THIS AREA. SURFACE TEMPS CURRENTLY RIGHT AROUND
FREEZING SO SNOW WILL BE WET. MAY EVEN MIX WITH RAIN THIS AFTERNOON.
BEHIND SURFACE FRONT AND AHEAD OF UPPER TROUGH AXIS PRECIP IS
TRANSITIONING BACK TO SNOW. SHORT-WAVE RIDGE OVER WESTERN BERING
RESULTING IN PARTLY CLOUDY SKIES ACROSS MUCH OF THE WESTERN BERING
AND ALEUTIANS. HOWEVER CIRRUS SHIELD FROM AN EASTERN RUSSIA LOW
QUICKLY SPREADING EASTWARD.

.FORECAST...GFS/ETA/UKMET AND YESTERDAYS 00Z RUN OF ECMWF ALL HANDLE
SYNOPTIC FEATURES SIMILARLY OUT TO 36 HOURS BEFORE DIVERGING. OF
COURSE...AS IS USUALLY THE CASE...THE DETAILS ARE A BIT DIFFERENT.
UPPER TROUGH OVER MAINLAND WILL FLATTEN EAST PACIFIC RIDGE TONIGHT
AS IT LIFTS ENE. THIS WILL LEAVE CUT OFF LOW SOUTH OF AKPENN TO
WANDER SLOWLY EASTWARD. SHORT-WAVE WILL THEN MOVE OUT OF EASTERN
RUSSIA AND MAY OR MAY NOT PHASE WITH CUT OFF LOW AND OPEN TO ONE
TROUGH. THIS IS WHERE MODELS DIVERGE. ETA/ECMFW DROP DIG SHORT-WAVE
SOUTHEASTWARD TOWARD CLOSED LOW WHILE UKMET/GFS KEEP SHORT-WAVE OVER
NORTHERN BERING. POSITION OF UPPER JET COMING OUT OF EAST ASIA AND
SOUTHEASTWARD ACROSS WESTERN ALEUTIANS SHOULD PUSH SHORT-WAVE
SOUTHEASTWARD. SO HAVE SIDED WITH THE ETA/ECMFW IN ALL AREAS FOR
THIS FORECAST PACKAGE. SO A SUMMARY OF THE FORECAST THINKING...PRECIP
WILL DIMINISH OVER SOUTH CENTRAL THIS EVENING AS SURFACE FRONT MOVES
EASTWARD. SINCE UPPER TROUGH AXIS WONT PUSH THROUGH UNTIL LATER
TONIGHT WILL BE CHANCE OF RAIN AND SNOW BEHIND THE FRONT. DO NOT
EXPECT ANY SIGNIFICANT ACCUMULATION. THERE WILL BE PARTIAL CLEARING
ONCE UPPER TROUGH MOVES THROUGH. THIS WILL PRODUCE AREAS OF FOG.
SHORT-WAVE RIDGE WILL NUDGE OVER TO SOUTH CENTRAL FRIDAY SO WILL
HAVE A CHANCE TO DRY OUT A BIT. MEANWHILE AS SHORT-WAVE AND
ASSOCIATED SURFACE LOW MOVE INTO WESTERN BERING FRIDAY TIGHT
PRESSURE GRADIENT WILL PRODUCE MAX GALES TO MIN STORMS FOR WESTERN
ALEUTIANS/WESTERN BERING. THIS GRADIENT WILL EASE AS SHORT-WAVE RIDGE
IS SQUASHED TO THE SOUTH. LOW WILL TRACK ACROSS SOUTHERN BERING AND
LOSE SUPPORT AS TROUGH AND UPPER LOW PHASE TO ONE TROUGH. AS HEAD
INTO WEEKEND TROUGH WILL LIFT NORTHWARD WITH RIDGE BEING PUSHED TO
WESTERN CANADA. THIS SHOULD BRING ANOTHER ROUND OF RAIN TO SOUTH
CENTRAL THIS WEEKEND. UNSETTLED WEATHER EXPECTED TO CONTINUE THROUGH
NEXT WEEK ACROSS MOST OF AOR AS UPPER LOW SETS UP OVER MAINLAND
ALASKA.

.AER...WATCH/WARNING SUMMARY
PUBLIC...HEAVY SNOW WARNING 145.
MARINE...NONE.
FIRE WEATHER...NONE.

SEB SEP 04

Event by event

2 flood. Local standard time, as filed.

Flood, Susitna Valley

When: October 1, 12:00 AM AST to 4:00 PM AST
Where: Susitna Valley forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Flood, Anchorage Muni to Bird Creek

When: October 1, 4:30 AM AST to 10:00 AM AST
Where: Anchorage Muni to Bird Creek forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

What these are

Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Alaska in 2004 Every state in 2004 This day in weather history Warnings in Alaska, October 2004

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5425092, 5425091.