251  
FGAK78 PACR 292313  
ESFAK  
AKZALL-140000-  
 
HYDROLOGIC OUTLOOK  
NWS ALASKA PACIFIC RIVER FORECAST CENTER ANCHORAGE AK  
2 PM ADT THU APRIL 27 2017  
   
..SPRING 2017 BREAKUP OUTLOOK FOR ALASKA.
 
 
 
BREAKUP IS PROGRESSING IN SOUTHCENTRAL AND SOUTHWEST ALASKA. THERE IS A FLOOD ADVISORY IN EFFECT FOR THE VILLAGE OF RED DEVIL ON THE KUSKOKWIM THROUGH MONDAY EVENING. THE KUSKOKWIM IS MOSTLY INTACT ICE BUT NIKOLAI AS WELL AS STONY RIVER, SLEETMUTE AND RED DEVIL HAVE BROKEN UP; AND THE CURRENT BREAKUP FRONT IS UPSTREAM OF CROOKED CREEK. THE SKWENTNA AND YENTNA RIVER ARE OPEN. THE CHENA AS WELL AS SECITONS OF THE TANANA ARE REPORTED OPEN.  
 
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 ALASKAN 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 SHORT AND LONG RANGE WEATHER FORECASTS.  
 
TEMPERATURES  
 
TEMPERATURES OVER THE NEXT FEW WEEKS ARE EXPECTED TO BE NEAR NORMAL IN  
EASTERN INTERIOR PARTS OF ALASKA AND INTO CANADA. THE REST OF THE STATE LIKELY  
TO HAVE ABOVE NORMAL TEMPERATURES. 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 ALONG THE  
CENTRAL TO WESTERN BROOKS RANGE AND INTO THE SEWARD PENINSULA. EXPECT ABOVE  
NORMAL PRECIPITATION SOUTH OF THE ALASKA RANGE AND INTO SOUTHWESTERN AND  
SOUTHEASTERN ALASKA. REMAINING LOCATIONS IN THE STATE ARE EXPECTED TO HAVE NEAR  
NORMAL PRECIPITATION. THE OUTLOOK FOR THE FOLLOWING WEEK SUGGESTS ABOVE NORMAL  
PRECIPITATION SOUTH OF THE ALASKA RANGE AND INTO SOUTHWESTERN AND SOUTHEASTERN  
ALASKA WITH THE REMAINING LOCATIONS AT NEAR NORMAL PRECIPITATION. 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 WITH ICE FLOES FROM UPSTREAM. ALSO THE YENTNA AT LAKE CREEK AND FISH CREEK ARE OPEN WITH ICE COMING DOWNSTREAM AND SHELF ICE STILL PRESENT.  
 
TANANA: THE TANANA RIVER HAS SOME SECTIONS OF OPEN WATER UPSTREAM BETWEEN THE CHENA AND SALCHA RIVER. BETWEEN BIG DELTA AND TANACROSS THE RIVER 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 AND UPPER PORTIONS HAVE 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 BROKEN UP.  
 
KUSKOKWIM: THERE IS A FLOOD ADVISORY IN EFFECT FOR RED DEVIL. NIKOLAI, STONY RIVER, SLEETMUTE AND RED DEVIL HAVE BROKEN UP. ICE IS IN PLACE BETWEEN NIKOLAI AND STONY RIVER; THERE IS OPEN WATER BETWEEN STONY RIVER AND RED DEVIL BUT AN ICE JAM 8 MILES DOWNSTREAM OF RED DEVIL IS CAUSING CHUNK ICE TO BACK UP AND RAISE WATER LEVELS NEAR RED DEVIL. FROM DOWNSTREAM OF RED DEVIL TO AKIAK, ICE IS IN PLACE. DOWNSTREAM OF AKIAK THERE ARE A FEW OPEN LEADS IN THE ICE.  
 
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 04/29-05/05  
SUNSHINE LOW 05/03 27 04/29-05/05  
 
YENTNA RIVER BELOW AVERAGE  
LAKE CREEK LOW 05/01 25 4/25**  
 
SKWENTNA RIVER BELOW AVERAGE  
SKWENTNA LOW 04/30 21 4/24**  
 
COPPER RIVER BASIN BELOW AVERAGE  
GAKONA RVR @ HWY LOW 05/01 29 4/28**  
GULKANA RVR @ HWY LOW 04/29 28 4/28**  
 
CHENA RIVER ABOVE AVERAGE  
CHENA LAKES PROJECT  
FAIRBANKS LOW-MOD 04/26 24 4/29**  
 
TANANA RIVER ABOVE AVERAGE  
CHISANA @ NORTHWAY LOW 04/26 27 4/25**  
SALCHA LOW-MOD 4/27**  
FAIRBANKS LOW 04/29 18 04/27-05/03  
NENANA LOW 04/30 37 04/28-05/04  
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 4/26**  
SLEETMUTE LOW-MOD 05/02 28 4/27**  
RED DEVIL LOW-MOD 05/05 31 4/28**  
CROOKED CREEK LOW-MOD 05/06 31 04/29-05/05  
ANIAK LOW-MOD 05/07 34 04/29-05/05  
KALSKAG LOW 05/07 28 04/29-05/05  
TULUKSAK LOW 05/08 25 04/30-05/06  
AKIAK LOW 05/10 31 05/02-05/08  
KWETHLUK LOW-MOD 05/10 6 04/29-05/05  
BETHEL LOW 05/11 37 04/29-05/05  
NAPAKIAK LOW 05/12 22 05/01-05/06  
 
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 MONDAY MAY 1 2017  
 

 
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