HYDROLOGIC OUTLOOK
NWS ALASKA PACIFIC RIVER FORECAST CENTER ANCHORAGE AK
200 PM ADT FRI APR 28 2006
...SPRING BREAKUP OUTLOOK FOR ALASKA...
THE FLOOD POTENTIAL FROM SNOWMELT AND ICE JAMS THIS SPRING BREAKUP
SEASON THROUGHOUT ALASKA IS CURRENTLY RATED AS AVERAGE. THIS
FORECAST IS BASED ON ICE THICKNESS REPORTS, OBSERVED SNOWPACK, AND
LONG RANGE TEMPERATURE FORECASTS.
WEATHER - THE GREATEST FACTOR IN DETERMINING THE SEVERITY OF BREAKUP
REMAINS THE WEATHER DURING APRIL AND MAY. WEATHER MODELS SUGGEST
CLOUDY WEATHER AND COOL TEMPERATURES FOR MUCH OF MAINLAND ALASKA
THROUGH THE FIRST WEEK IN MAY. COLDER THAN NORMAL TEMPERATURES DELAY
THE MELTING OF THE SNOWPACK AND THE DECAY OF THE RIVER ICE. THE
THREAT OF SNOWMELT AND ICE JAM FLOODING WILL DEPEND ON THE TIMING AND
RATE OF CHANGE FROM BELOW NORMAL TO NORMAL OR ABOVE NORMAL
TEMPERATURES. FOR MORE INFORMATION ON THE OUTLOOKS FOR THIS SPRING
PLEASE REFER TO THE CLIMATE PREDICTION CENTER WEB SITE AT...
http://www.cpc.ncep.noaa.gov/
ICE - APRIL ICE THICKNESS DATA IS AVAILABLE FOR A LIMITED NUMBER OF
OBSERVING SITES IN ALASKA. MEASUREMENTS INDICATE THAT ICE THICKNESS
IS NORMAL OR BELOW NORMAL AT MOST LOCATIONS. THE NOTED EXCEPTIONS
ARE THE TANANA RIVER BASIN WHERE ICE THICKNESS IS 100-145% OF NORMAL
AND THE MIDDLE YUKON RIVER AT NULATO WHERE THE ICE IS 123% OF NORMAL
THICKNESS.
SNOW - AN ANALYSIS OF THE APRIL 1 SNOWPACK INDICATES BELOW NORMAL
SNOWPACK THROUGHOUT MUCH OF SOUTHERN MAINLAND ALASKA AND THE
SOUTHEAST PANHANDLE. LATE APRIL SNOWPACK MEASUREMENTS IN
SOUTHCENTRAL INDICATE THAT THE COOL APRIL WEATHER AND ASSOCIATED
REDUCED MELT RATES MAY BRING THE MAY 1 SNOWPACK CLOSER TO NORMAL.
PORTIONS OF THE YUKON TERRITORY, THE UPPER AND MIDDLE YUKON BASIN,
AND THE THE KOYUKUK RIVER BASIN HAD AVERAGE SNOWPACKS IN EARLY APRIL.
THE TALKEETNA MOUNTAINS AND THE SUSITNA VALLEY HAD 55-75% OF NORMAL
SNOWPACKS APRIL 1, WHEREAS LAST YEAR THESE SAME AREAS HAD SNOWPACKS
WELL OVER 150% OF NORMAL. EVEN WITH BELOW NORMAL SNOWPACKS IF
TEMPERATURES REMAIN COOL THROUGH EARLY MAY THERE IS ENOUGH SNOW IN
MOST AREAS TO PRODUCE SIGNIFICANT SNOWMELT RUNOFF PEAKS IF SUBJECTED
TO A RAPID WARMING PATTERN IN EARLY TO MID MAY. THIS IS PARTICULARLY
TRUE BECAUSE MOST OF THE STATE STILL HAS SIGNIFICANT SNOW COVER EVEN
AT LOW ELEVATIONS AND IS STILL RECEIVING LATE SEASON SNOW.
FOR MORE DETAILS ON THE APRIL 1 SNOWPACK PLEASE REFER TO THE VARIOUS
SNOW GRAPH OPTIONS AT THE APRFC WEB SITE AT...
http://aprfc.arh.noaa.gov/
OR ON THE NRCS WEB SITE AT...
http://ambcs.org/
UNDER SNOWPACK REPORTS OR SNOWPACK MAPS.
THE FOLLOWING TABLE GIVES AN ESTIMATION OF FLOOD POTENTIAL FOR
VARIOUS LOCATIONS AROUND THE STATE AND BASIN RUNOFF VOLUMES.
_____________________________________________________________________
SNOWMELT RUNOFF VOLUME...EXPECTED WATER VOLUME FROM SNOWMELT DURING
THE MELT SEASON.
FLOOD POTENTIAL...THE LIKELIHOOD OF FLOODING FROM SNOWMELT AND/OR
ICE JAMS.
* AVERAGE BREAKUP DATES ARE FOR THE PERIOD 1970 THROUGH 2005 AND ARE
CALCULATED FOR LOCATIONS WITH AT LEAST 5 YEARS OF DATA.
** ACTUAL BREAKUP DATE FOR THIS YEAR
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SNOWMELT FLOOD AVERAGE NO. OF FORECAST
RIVER - REACH RUNOFF POTENTIAL BREAKUP YEARS BREAKUP
VOLUME DATE * RECORD DATE
------------- ---------- --------- ------- ------ --------
SOUTHEAST PANHANDLE BELOW
KENAI RIVER BELOW
MATANUSKA RIVER BELOW LOW
SUSITNA RIVER BELOW
GOLD CREEK LOW
SUNSHINE LOW 05/02 16 5/01-5/06
YENTNA RIVER BELOW LOW
COPPER RIVER BASIN BELOW
GAKONA RVR @ HWY LOW 04/29 19 4/30-5/05
GULKANA RVR @ HWY LOW 04/28 17 4/29-5/04
CHENA RIVER BELOW
CHENA LAKES PROJECT LOW
FAIRBANKS LOW 04/25 20 4/29-5/02
TANANA RIVER BELOW
NORTHWAY LOW 04/22 19 4/27**
SALCHA HIGH
FAIRBANKS LOW 04/29 7 4/30-5/04
NENANA LOW 05/02 32 5/01-5/05
MANLEY LOW 05/03 15 5/03-5/07
KUSKOKWIM RIVER (UPPER) BELOW
NIKOLAI LOW-MOD 04/23 20 4/25**
MCGRATH MODERATE 05/07 31 5/06-5/12
KUSKOKWIM RIVER (LOWER) BELOW
STONY RIVER LOW-MOD 05/06 17 5/04-5/11
SLEETMUTE MODERATE 05/04 17 5/04-5/09
RED DEVIL MODERATE 05/06 19 5/05-5/11
CROOKED CREEK MODERATE 05/07 20 5/05-5/11
ANIAK MODERATE 05/07 22 5/06-5/13
KALSKAG MODERATE 05/07 16 5/07-5/13
TULUKSAK MODERATE 05/09 13 5/09-5/15
AKIAK MODERATE 05/10 19 5/10-5/16
BETHEL MODERATE 05/12 34 5/11-5/17
YUKON RIVER (UPPER) AVERAGE
EAGLE LOW-MOD 05/05 26 5/04-5/10
CIRCLE MOD-HIGH 05/10 23 5/08-5/13
FORT YUKON MODERATE 05/10 23 5/09-5/14
BEAVER LOW 05/12 10 5/10-5/15
STEVENS VILLAGE LOW 05/14 9 5/12-5/17
RAMPART LOW 05/14 10 5/12-5/17
YUKON RIVER (MIDDLE) AVERAGE
TANANA LOW 05/10 20 5/08-5/13
RUBY LOW 05/12 22 5/10-5/15
GALENA MODERATE 05/12 23 5/10-5/15
KOYUKUK MODERATE 05/13 5/11-5/16
NULATO MODERATE 05/14 9 5/11-5/17
KALTAG LOW 05/14 29 5/11-5/17
ANVIK LOW 05/18 17 5/15-5/21
YUKON RIVER (LOWER) BELOW
HOLY CROSS LOW 05/16 17 5/14-5/19
RUSSIAN MISSION LOW-MOD 05/15 20 5/13-5/19
PILOT STATION LOW-MOD 05/17 8 5/15-5/20
MOUNTAIN VILLAGE LOW 05/19 17 5/17-5/22
ALAKANUK/EMMONAK MOD-HIGH 05/22 22 5/19-5/25
KOYUKUK RIVER AVERAGE
BETTLES LOW 05/10 25 5/08-5/14
ALLAKAKET LOW-MOD 05/11 20 5/09-5/14
HUGHES LOW-MOD 05/12 19 5/10-5/15
SEWARD PENINSULA BELOW
BUCKLAND RIVER BELOW
BUCKLAND MODERATE 05/18 14 5/15-5/23
KOBUK RIVER BELOW
KOBUK MODERATE 05/17 25 5/15-5/21
SHUNGNAK LOW 05/19 15 5/17-5/22
AMBLER LOW 05/18 22 5/16-5/22
NOATAK RIVER BELOW
NOATAK LOW 05/20 11 5/17-5/23
BROOKS RANGE - NORTH BELOW
COLVILLE @ UMIAT LOW 05/24 9 5/22-5/28
COLVILLE @ COLVILLE LOW 05/31 7 5/28-6/04
ARCTIC COASTAL BELOW
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FOR MORE DETAIL AND TO SEE A FLOOD POTENTIAL MAP REFER TO OUR WEB
SITE AT...
http://aprfc.arh.noaa.gov/
IF YOU HAVE ANY COMMENTS OR QUESTIONS REGARDING THIS FORMAT PLEASE EMAIL...
Becky.Perry@noaa.gov
THIS IS THE LAST BREAKUP OUTLOOK FOR THE SEASON. THE SPRING BREAKUP
SUMMARY IS SCHEDULED TO START UP AT 2 PM MONDAY MAY 1.
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