014  
FGAK78 PACR 242233  
ESFAK  
AKZALL-140000-  
 
HYDROLOGIC OUTLOOK  
NWS ALASKA PACIFIC RIVER FORECAST CENTER ANCHORAGE AK  
2 PM ADT MON APRIL 24 2017  
   
..SPRING 2017 BREAKUP OUTLOOK FOR ALASKA.
 
 
 
SEVERAL LOCATIONS ARE REPORTED AS OPEN. SHORT RANGE TEMPERATURE AND  
PRECIPITATION FORECASTS HAVE CHANGED SLIGHTLY SINCE PAST FRIDAY'S OUTLOOK, BUT  
HAVE NOT INFLUENCED ANY CHANGES TO THE BREAKUP FORECAST. OBSERVERS ARE REPORTING  
SOME OPEN WATER ALONG THE SUSITNA, TANANA, NENANA, COPPER, SUSITNA, AND UPPER  
KUSKOKWIM RIVERS. REPORTS SUGGEST CAUTION SHOULD BE EXERCISED WHILE TRAVELING ON  
THE KUSKOKWIM RIVER NEAR BETHEL AND BELOW AND ABOVE AKIAK. OPEN LEADS HAVE BEEN  
SEEN ALONG THE YUKON RIVER NEAR EAGLE, AK. MANY SMALL STREAMS AROUND THE  
BUCKLAND AREA ARE REPORTED AS HAVING DARK ICE. SEE BELOW FOR DETAILS.  
 
THE FLOOD POTENTIAL FROM SNOWMELT AND ICE JAMS THROUGHOUT MOST OF ALASKA THIS  
SPRING IS CURRENTLY RATED AS NORMAL. THIS WOULD INDICATE THAT LOCATIONS THAT  
OFTEN EXPERIENCE FLOODING DURING BREAKUP ARE LIKELY TO SEE MINOR FLOODING IF AN  
ICE JAM FORMS DOWNSTREAM. THE CENTRAL TANANA VALLEY HAS A SLIGHTLY HIGHER RISK  
OF MINOR FLOODING THIS SPRING DUE TO A GREATER THAN NORMAL WINTER SNOWPACK.  
 
BREAKUP ALONG THE MIDDLE AND LOWER YUKON RIVER AND TANANA RIVER IS EXPECTED TO  
BE 1 TO 3 DAYS EARLIER THAN AVERAGE, WHILE BREAKUP ALONG THE KUSKOKWIM AND OTHER  
SOUTHEAST AND SOUTHERN ALASKA RIVERS IS EXPECTED TO BE 2 TO 4 DAYS EARLIER THAN  
AVERAGE. THIS STATEWIDE FORECAST IS BASED ON CURRENT ICE THICKNESS, OBSERVED  
SNOWPACK, RIVER FREEZE-UP STAGE, AND LONG RANGE WEATHER FORECASTS.  
 
TEMPERATURES  
 
TEMPERATURES OVER THE NEXT WEEK ARE EXPECTED TO BE ABOVE NORMAL IN NORTHERN,  
WESTERN AND SOUTHWESTERN ALASKA. THE REST OF THE STATE LIKELY TO HAVE NEAR  
NORMAL TEMPERATURES. TEMPERATURES OVER THE FOLLOWING WEEK ARE EXPECTED TO BE  
ABOVE NORMAL IN NORTHERN, WESTERN, AND SOUTHWESTERN ALASKA WITH TEMPERATURES  
IN THE SUSITNA, MATANUSKA, COPPER, AND CANADIAN YUKON RIVER BASINS EXPECTED TO  
BE BELOW NORMAL. THE OUTLOOK FOR THE MONTH OF MAY SUGGESTS NORTH SLOPE  
TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL, WITH ABOVE NORMAL TEMPERATURES  
SOUTH OF THE BROOKS RANGE INTO SOUTHERN PARTS OF THE STATE.  
 
PRECIPITATION  
 
OVER THE NEXT WEEK, PRECIPITATION IS EXPECTED TO BE BELOW NORMAL IN NORTHWESTERN  
ALASKA AND ALONG THE NORTH SLOPE. PRECIPITATION ALONG THE YUKON RIVER VALLEY AND  
THE PORCUPINE BASIN EXPECTED TO BE NEAR NORMAL. EXPECT ABOVE NORMAL  
PRECIPITATION IN THE CANADIAN YUKON. PRECIPITATION IN SOUTHERN PARTS OF THE  
STATE EXPECTED TO BE ABOVE NORMAL. PRECIPITATION OVER THE FOLLOWING WEEK IS  
EXPECTED TO BE BELOW NORMAL IN NORTHWESTERN ALASKA. NEAR NORMAL PRECIPITATION IS  
EXPECTED IN THE NORTHERN PORTIONS OF THE LOWER, MIDDLE, AND UPPER YUKON RIVER  
VALLEY AND THE PORCUPINE BASIN. ABOVE NORMAL PRECIPITATION IS EXPECTED IN  
SOUTHERN LOCATIONS OF THE YUKON RIVER VALLEY TO SOUTHWESTERN AND SOUTHERN ALASKA  
AND INTO THE CANADIAN YUKON. THE MAY OUTLOOK SUGGESTS BELOW NORMAL PRECIPITATION  
ALONG THE WESTERN COAST TO JUST NORTH OF THE SEWARD PENINSULA. NORMAL AMOUNTS OF  
PRECIPITATION ARE EXPECTED IN ALL OTHER LOCATIONS OF THE STATE.  
 
FOR MORE INFORMATION ON THE OUTLOOKS, PLEASE REFER TO THE CLIMATE PREDICTION  
CENTER WEBSITE HTTP://WWW.CPC.NCEP.NOAA.GOV/  
 
ICE CONDITIONS  
 
APRIL ICE THICKNESS DATA ARE AVAILABLE FOR A LIMITED NUMBER OF OBSERVING SITES  
IN ALASKA. APRIL 1ST MEASUREMENTS INDICATE THAT ICE THICKNESS IS GENERALLY  
SLIGHTLY ABOVE NORMAL ACROSS MOST OF THE STATE.  
 
SNOWPACK  
 
AN ANALYSIS OF THE APRIL 1ST SNOWPACK BY THE NATURAL RESOURCES CONSERVATION  
SERVICE (NRCS) INDICATES A GENERALLY BELOW NORMAL SNOWPACK SOUTH OF THE ALASKA  
RANGE, INCLUDING SOUTHEAST ALASKA. NORTH OF THE ALASKA RANGE, THERE IS AN AREA  
OF WELL ABOVE NORMAL SNOWPACK EAST OF FAIRBANKS, BUT OVERALL AVERAGES WITHIN THE  
MIDDLE AND UPPER YUKON BASINS ARE CLOSE TO NORMAL. SNOWPACK CONDITIONS ALONG THE  
DALTON HIGHWAY ON THE NORTH SLOPE OF ALASKA ARE NEAR NORMAL. FOR MORE DETAILS,  
PLEASE REFER TO THE VARIOUS SNOW GRAPHICS FROM THE ALASKA-PACIFIC RIVER FORECAST  
CENTER (APRFC) OR FROM THE NATURAL RESOURCES CONSERVATION SERVICE (NRCS).  
 
FOR WEATHER, ICE, AND SNOW CONDITIONS, PLEASE REFER TO  
HTTP://WWW.WEATHER.GOV/APRFC/FGAK78PACR AND FOR VARIOUS SNOW GRAPH OPTIONS REFER  
TO THE APRFC WEBSITE AT HTTP://WWW.WEATHER.GOV/APRFC OR THE NRCS WEBSITE AT  
HTTP://WWW.NRCS.USDA.GOV/WPS/PORTAL/NRCS/MAIN/AK/SNOW/  
 
BREAKUP  
 
THE BREAKUP OF RIVER ICE GENERALLY FALLS BETWEEN DYNAMIC AND THERMAL PROCESSES.  
A THERMAL BREAKUP COMMONLY OCCURS WHEN SNOWMELT AND OTHER RUNOFF WATER IS  
INSUFFICIENT TO INFLUENCE ICE MOVEMENT AND THE ICE ROTS IN PLACE. DURING A  
THERMAL BREAKUP, ICE STRENGTH SIGNIFICANTLY DETERIORATES, BUT THE MOVEMENT OF  
ICE AND SNOWMELT DOWNSTREAM DOES NOT FORM A COHERENT BREAKUP FRONT. IN THIS CASE  
MULTIPLE LOCATIONS MIGHT SEE SIMULTANEOUS ICE MOVEMENT. FLOODING FROM ICE JAMS  
DURING A THERMAL BREAKUP IS RARELY SERIOUS, ALTHOUGH STILL POSSIBLE. DURING A  
THERMAL PROCESS, BREAKUP TIMING AT LOCATIONS MIGHT RANGE FROM SEVERAL DAYS  
EARLIER TO SEVERAL DAYS LATER THAN EXPECTED AND IS OFTEN INCONSISTENT UP AND  
DOWN THE RIVER. NORMALLY, SPRING BREAKUP IS DYNAMIC, PROGRESSING FROM RIVER  
HEADWATERS TO DOWNSTREAM LOCATIONS. DYNAMIC BREAKUPS ARE CHARACTERIZED BY HAVING  
HIGHER FLOWS, MORE POTENTIAL FOR ICE JAMS, AND FLOODING FROM THESE EVENTS CAN BE  
CATASTROPHIC. TYPICALLY A DYNAMIC BREAKUP PROGRESSES FROM UPSTREAM TO  
DOWNSTREAM. MOST DYNAMIC BREAKUPS OCCUR WHEN AIR TEMPERATURES SHIFT FROM BEING  
COOLER THAN NORMAL TO WARMER THAN NORMAL.  
 
FROM THE EXPECTED STATEWIDE TEMPERATURE OUTLOOKS, THE 2017 BREAKUP SEASON IS  
EXPECTED TO BE EARLIER THAN AVERAGE SOUTH OF THE BROOKS RANGE. BREAKUP ALONG THE  
NORTH SLOPE, AND PORCUPINE AND CANADIAN YUKON RIVERS IS EXPECTED TO BE ON  
AVERAGE. BREAKUP ALONG THE MIDDLE AND LOWER YUKON RIVER AND TANANA RIVER IS  
EXPECTED TO BE 1 TO 3 DAYS EARLIER THAN AVERAGE, WHILE BREAKUP ALONG THE  
KUSKOKWIM AND OTHER SOUTHEAST AND SOUTHERN ALASKA RIVERS IS EXPECTED TO BE 2 TO  
4 DAYS EARLIER THAN AVERAGE.  
 
OBSERVED RIVER CONDITIONS  
 
SUSITNA: TALKEETNA HAS OPEN WATER NEAR THE RAILROAD BRIDGE. THE CHULITNA  
AND SUSITNA RIVERS HAVE SOME OPEN WATER. DESHKA RIVER HAS OPEN LEADS FORMING.  
SKWENTNA RIVER AT SKWENTNA IS OPEN.  
 
TANANA: THE TANANA RIVER HAS SOME OPEN WATER UPSTREAM OF CHENA RIVER TO THE  
SALCHA RIVER.THE TANANA RIVER BETWEEN BIG DELTA AND TANACROSS IS MOSTLY OPEN.  
SOME OPEN WATER HAS BEEN REPORTED ALONG THE MID SECTION OF NENANA RIVER. THE  
LOWER PORTION OF CHENA RIVER IS MOSTLY OPEN WATER AND THE MID PORTION HAS SOME  
OPEN WATER. THE LOWER PORTION OF SALCHA RIVER HAS SOME OPEN WATER.  
 
COPPER RIVER: SOME OPEN WATER HAS BEEN REPORTED ALONG THE COPPER RIVER BETWEEN  
CHRISTOCHINA SOUTH TO COPPER CENTER. GAKONA AND GULKANA RIVERS HAVE OPEN LEADS.  
 
KUSKOKWIM: NIKOLAI IS OPEN. SOME OPEN WATER HAS BEEN OBSERVED UPSTREAM OF  
NIKOLAI NEAR OLD NIKOLAI. REPORTS SUGGEST CAUTION SHOULD BE EXERCISED WHILE  
TRAVELING ON THE RIVER NEAR BETHEL AND BELOW AND ABOVE AKIAK.  
 
YUKON: PILOTS HAVE REPORTED A FEW OPEN LEADS ALONG THE YUKON RIVER SHORE NEAR  
EAGLE, AK AND THE CANADIAN/U.S BORDER.  
 
--------------------------------------------------------------------------------  
THE FOLLOWING TABLE GIVES (1) AN ESTIMATE OF FLOOD POTENTIAL FOR VARIOUS  
LOCATIONS AROUND THE STATE AND (2) 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. THIS  
IS INITIALLY CALCULATED BASED ON THE FLOOD FREQUENCY FOR THE 2000 TO 2016  
HISTORICAL RECORD AND ADJUSTED TO REFLECT CURRENT CONDITIONS.  
 
* AVERAGE BREAKUP DATES ARE FOR THE 1980-2016 PERIOD AND ARE CALCULATED FOR  
LOCATIONS WITH AT LEAST 5 YEARS OF DATA.  
 
** ACTUAL BREAKUP DATE FOR THIS YEAR.  
--------------------------------------------------------------------------------  
 
SNOWMELT FLOOD AVERAGE NO. OF FORECAST  
RIVER - REACH RUNOFF POTENTIAL BREAKUP YEARS BREAKUP  
VOLUME DATE * USED DATE  
------------- ---------- --------- ------- ------ --------  
SOUTHEAST PANHANDLE  
 
KENAI RIVER OPEN  
 
ANCHOR RIVER BELOW AVERAGE LOW 04/14 11 4/13**  
 
MATANUSKA RIVER BELOW AVERAGE 04/30 8 OPEN  
 
SUSITNA RIVER BELOW AVERAGE  
GOLD CREEK LOW 05/03 8 04/27-05/03  
SUNSHINE LOW 05/03 27 04/27-05/03  
 
YENTNA RIVER BELOW AVERAGE  
LAKE CREEK LOW 05/01 25 04/28-05/01  
 
SKWENTNA RIVER BELOW AVERAGE  
SKWENTNA LOW 04/30 21 4/24**  
 
COPPER RIVER BASIN BELOW AVERAGE  
GAKONA RVR @ HWY LOW 05/01 29 04/25-05/01  
GULKANA RVR @ HWY LOW 04/29 28 04/23-04/29  
 
CHENA RIVER ABOVE AVERAGE  
CHENA LAKES PROJECT  
FAIRBANKS LOW-MOD 04/26 24 04/22-04/28  
 
TANANA RIVER ABOVE AVERAGE  
CHISANA @ NORTHWAY LOW 04/26 27 04/22-04/28  
SALCHA LOW-MOD  
FAIRBANKS LOW 04/29 18 04/24-04/30  
NENANA LOW 04/30 37 04/25-05/01  
MANLEY LOW 05/04 27 04/30-05/06  
 
KUSKOKWIM RIVER BELOW AVERAGE  
NIKOLAI LOW 04/23 31 4/23**  
MCGRATH LOW-MOD 05/05 37 04/30-05/06  
STONY RIVER LOW 05/02 29 04/30-05/06  
SLEETMUTE LOW-MOD 05/02 28 04/28-05/04  
RED DEVIL LOW-MOD 05/05 31 04/29-05/05  
CROOKED CREEK LOW-MOD 05/06 31 04/30-05/06  
ANIAK LOW-MOD 05/07 34 05/01-05/07  
KALSKAG LOW 05/07 28 05/01-05/07  
TULUKSAK LOW 05/08 25 05/03-05/09  
AKIAK LOW 05/10 31 05/03-05/09  
KWETHLUK LOW-MOD 05/10 6 05/03-05/09  
BETHEL LOW 05/11 37 05/04-05/10  
NAPAKIAK LOW 05/12 22 05/05-05/11  
 
YUKON RIVER (UPPER) AVERAGE  
DAWSON, YT 05/04 36 04/30-05/06  
EAGLE LOW-MOD 05/04 36 04/30-05/06  
CIRCLE MOD 05/08 33 05/04-05/10  
FORT YUKON LOW-MOD 05/10 33 05/05-05/11  
BEAVER LOW 05/10 21 05/06-05/12  
STEVENS VILLAGE LOW-MOD 05/11 20 05/07-05/13  
RAMPART LOW 05/11 22 05/07-05/13  
 
YUKON RIVER (MIDDLE) AVERAGE  
TANANA LOW 05/08 32 05/05-05/11  
RUBY LOW 05/09 31 05/06-05/12  
GALENA LOW-MOD 05/11 36 05/07-05/13  
KOYUKUK LOW-MOD 05/09 12 05/07-05/13  
NULATO LOW-MOD 05/10 21 05/07-05/13  
KALTAG LOW 05/12 31 05/09-05/15  
ANVIK LOW 05/14 30 05/11-05/17  
 
YUKON RIVER (LOWER) AVERAGE  
HOLY CROSS LOW 05/15 30 05/10-05/16  
RUSSIAN MISSION LOW 05/16 31 05/09-05/15  
MARSHALL LOW-MOD 05/15 25 05/10-05/16  
PILOT STATION LOW 05/16 20 05/11-05/17  
MOUNTAIN VILLAGE LOW 05/19 30 05/12-05/18  
ALAKANUK/EMMONAK MOD 05/21 32 05/17-05-23  
 
KOYUKUK RIVER AVERAGE  
BETTLES LOW 05/10 35 05/07-05/13  
ALLAKAKET LOW 05/10 31 05/07-05/13  
HUGHES LOW-MOD 05/11 30 05/07-05/14  
 
SEWARD PENINSULA AVERAGE  
BUCKLAND MOD 05/20 26 05/17-05/23  
 
KOBUK RIVER AVERAGE  
KOBUK LOW-MOD 05/14 33 05/11-05/17  
SHUNGNAK LOW 05/17 27 05/14-05/20  
AMBLER LOW 05/18 33 05/15-05/21  
 
NOATAK RIVER AVERAGE  
NOATAK LOW 05/19 22 05/16-05/22  
 
BROOKS RANGE - NORTH AVERAGE  
COLVILLE @ UMIAT LOW 05/25 17 05/22-05/28  
COLVILLE @ COLVILLE LOW-MOD 06/04 19 06/01-06/07  
 
SAGAVANIRKTOK RIVER AVERAGE  
DALTON HWY LOW-MOD **/**  
 
FOR MORE DETAIL AND TO SEE A FLOOD POTENTIAL MAP REFER TO OUR WEBSITE AT  
HTTP://WWW.WEATHER.GOV/APRFC/  
 
THE NEXT SPRING BREAKUP OUTLOOK IS SCHEDULED AT 2 PM ADT TUESDAY APRIL 25 2017  
 

 
EHM  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab RFC Page Main Text Page