Flood Potential Outlook
Issued by NWS Caribou, ME

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
531 PM EDT THU APR 3 2014

...WINTER AND SPRING FLOOD POTENTIAL OUTLOOK FOR NORTHERN...
CENTRAL AND DOWNEAST MAINE...

THIS IS THE EIGHTH WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR
2014...ISSUED BY THE NATIONAL WEATHER SERVICE IN CARIBOU, MAINE.
THE WINTER/SPRING FLOOD POTENTIAL IS FOR NORTHERN, CENTRAL AND
DOWNEAST MAINE FOR THE TWO WEEK PERIOD FROM APRIL 3 TO APRIL 17,
2014.

THE WINTER/SPRING FLOOD POTENTIAL FOR ALL OF NORTHERN, CENTRAL,
AND DOWNEAST MAINE IS ABOVE NORMAL. THIS INCLUDES THE POTENTIAL
FOR FLOODING DUE TO ICE JAMS.

...CLIMATOLOGICAL GUIDANCE...

WHILE THE LATTER HALF OF MARCH DID SEE A FEW BRIEF WARM UPS, THE
OVERALL TREND OVER THE PAST COUPLE OF WEEKS HAS CONTINUED TO BE
COLDER THAN NORMAL. MANY LOCATIONS FINISHED MARCH WITH AVERAGE
MONTHLY TEMPERATURES SOME 6 TO 10 DEGREES COLDER THAN NORMAL. THE
ACTIVE WEATHER TREND HAS ALSO CONTINUED. A VERY STRONG DEVELOPING
LOW PRESSURE BROUGHT HEAVY SNOW TO MUCH OF THE FORECAST AREA,
ESPECIALLY PORTIONS OF DOWNEAST, AT THE END OF LAST MONTH. THIS NOT
ONLY ADDED TO THE SNOWPACK, IT ALSO ADDED LIQUID TO THE ALREADY
WATER-LADEN SNOW.

THIS ACTIVE PATTERN WILL CONTINUE INTO MID APRIL WITH SEVERAL
SYSTEMS TO AFFECT THE AREA. A LOW PRESSURE SYSTEM WILL BRING A
SLUG OF PRECIPITATION TO THE PINE TREE STATE THIS WEEKEND,
STARTING OUT AS A WINTRY MIX BUT CHANGING TO RAIN OVER ALL BUT
THE FAR NORTHWEST. STORM TOTAL QPF FROM THIS SYSTEM WILL BE ONE-
HALF TO THREE-QUARTERS OF AN INCH. A STRONGER LOW WILL THEN MOVE
ACROSS WESTERN AND NORTHERN MAINE EARLY NEXT WEEK. THE MODELS HAVE
BEEN TRENDING WARMER WITH THIS SYSTEM, SO MUCH OF ITS PRECIPITATION
WILL FALL AS RAIN. THESE SYSTEMS WILL ONLY SERVE TO ADD EVEN MORE
WATER TO THE SNOWPACK. IN ADDITION, ALTHOUGH COLDER THAN NORMAL
CONDITIONS ARE ALSO EXPECTED TO LINGER OVER THE NEXT SEVERAL DAYS,
DAYTIME TEMPERATURES WILL BE WARM ENOUGH TO ALLOW FOR SNOWMELT.
THE OFFICIAL NATIONAL WEATHER SERVICE 6 TO 10 DAY FORECAST
CONTINUES TO CALL FOR COLDER THAN NORMAL AND WETTER THAN NORMAL
CONDITIONS.

...OBSERVED SNOW DEPTH AND WATER EQUIVALENTS...

SNOW DEPTHS AND THE WATER CONTAINED IN THE PACK CONTINUE TO BE
WELL ABOVE NORMAL ACROSS OUR ENTIRE FORECAST AREA. NORTHERN AREAS
CURRENTLY HAVE 3 TO 4 FEET OF SNOW ON THE GROUND, WITH 30 TO 40
INCHES IN MUCH OF THE CENTRAL HIGHLANDS. THE AMOUNT OF SNOW ON THE
GROUND DECREASES AS YOU HEAD SOUTH, WITH INTERIOR DOWNEAST
STATIONS REPORTING 1 TO 2 FEET. ALONG THE COAST, THERE IS
GENERALLY A FOOT OR LESS OF SNOW COVERING THE GROUND.

THE SNOW WATER EQUIVALENT, OR THE AMOUNT OF WATER CONTAINED IN
THE SNOWPACK, IS GREATEST IN AN EAST-WEST BAND STRETCHING FROM
SOUTHERN AROOSTOOK COUNTY BACK THROUGH MILLINOCKET, DOVER-
FOXCROFT, AND GREENVILLE. IN THESE AREAS, THE SNOW CONTAINS 10 TO
12 INCHES OF WATER. FURTHER NORTH, THE SNOW IS LESS DENSE OWING
TO COLDER TEMPERATURES AND LESS MELTING. NORTHERN AREAS GENERALLY
HAVE 6 TO 10 INCHES OF WATER. INTERIOR DOWNEAST HAS 5 TO 8 INCHES
OF WATER HELD IN ITS SNOW, WHILE COASTAL AREAS GENERALLY ONLY
HAVE 2 TO 5 INCHES. THESE SWES ARE WITHIN THE UPPER 25% OF
HISTORICAL NORMAL AMOUNTS, WITH PORTIONS OF DOWNEAST UP INTO THE
CENTRAL HIGHLANDS IN THE UPPER 10%.

...SOIL MOISTURE AND WATER SUPPLY CONDITIONS...

WHILE THE BRIEF AFOREMENTIONED WARM UPS HAVE ALLOWED FOR SOME
RUNOFF, NEAR SURFACE SOIL MOISTURE REMAINS NEAR NORMAL OVER MUCH
OF THE REGION. THE EXCEPTION IS ACROSS NORTHERN MAINE, WHERE THE
SOIL IS A BIT WETTER THAN NORMAL OWING TO THE DEEPER SNOWPACK. THE
PALMER DROUGHT INDEX, WHICH MEASURES THE LONGER-TERM GROUND
MOISTURE, IS NEAR NORMAL. GROUNDWATER LEVELS ACROSS THE STATE ARE
EITHER NEAR OR BELOW NORMAL. THIS MAKES SENSE SEEING AS WE`VE HAD
LESS RUNOFF THAN WHAT WE WOULD NORMALLY SEE THIS TIME OF YEAR DUE
TO THE COLD TEMPERATURES.

...RIVER AND ICE CONDITIONS...

AREA RIVERS CONTINUE TO SHOW BELOW NORMAL FLOWS FOR THIS TIME OF
YEAR. THE EXCEPTION IS THE FAR NORTHERN WATERWAYS, INCLUDING THE
SAINT JOHN, AROOSTOOK, AND ALLAGASH, WHICH ARE CLOSER TO NORMAL.
THIS IS BECAUSE WHILE CENTRAL AND ESPECIALLY SOUTHERN MAINE ARE
USUALLY IN FULL SNOWMELT MODE BY EARLY APRIL, NORTHERN MAINE`S
SNOWMELT SEASON TYPICALLY IS JUST GETTING STARTED. OVERALL, IT
SHOULD BE NOTED THAT OUR RIVERS ARE RUNNING 2 TO 3 WEEKS BEHIND
THE NORMAL SPRING SCHEDULE AS FAR AS FLOWS AND ICE COVER ARE
CONCERNED.

RIVER ICE REMAINS VERY WELL-ESTABLISHED ACROSS THE NORTHERN AND
CENTRAL RIVERS. THICKNESSES AROUND 2 FEET ARE COMMON ALONG THE
SAINT JOHN, ALLAGASH, AND AROOSTOOK RIVERS, WITH UP TO 3 FEET
POSSIBLE IN THE UPPER REACHES. THE PISCATAQUIS IS STILL VERY MUCH
FROZEN FOR MUCH OF ITS LENGTH AS WELL, WITH ICE THICKNESSES OF 3
FEET BEING REPORTED IN BLANCHARD, ABBOT, AND MEDFORD. THIS IS ALL
ABOVE NORMAL FOR THIS TIME OF YEAR. FURTHER SOUTH, THE ICE COVER
ON THE PENOBSCOT HAS SHOWN WEAKENING OVER THE PAST WEEK AS
SUNSHINE AND WARMER WATER FROM RUNOFF HAVE BEGUN TO ERODE THE ICE
FROM BOTH THE TOP AND BOTTOM. THE PENOBSCOT RIVER FROM MEDWAY TO
HOWLAND IS OPEN IN THE MIDDLE OF ITS COURSE FOR SEVERAL STRETCHES
AND WHAT ICE COVER REMAINS IS RAPIDLY TURNING GRAY. OUR DOWNEAST
WATERWAYS GENERALLY HAVE ICE THAT IS 1 FOOT OR LESS IN THICKNESS.
THIS ICE COVER IS CLOSER TO NORMAL, WITH FAR INTERIOR DOWNEAST
STILL ABOVE NORMAL FOR ICE.

SEVERAL JAMS REMAIN LOCKED IN PLACE ACROSS CARIBOU`S FORECAST
AREA. THESE INCLUDE BUT ARE NOT LIMITED TO ICE JAMS ON THE SAINT
JOHN UPSTREAM OF FORT KENT, THE EAST BRANCH OF THE PENOBSCOT
RIVER DOWNSTREAM OF GRINDSTONE AND THE PISCATAQUIS RIVER UPSTREAM
OF HOWLAND. IN ADDITION, ICE JAMS ON THE AROOSTOOK RIVER BETWEEN
PRESQUE ISLE AND CARIBOU HAVE BEEN REPORTED BY NWS STAFF. IT
SHOULD BE NOTED THAT WE RECEIVED INFORMATION FROM A MEMBER OF THE
PUBLIC LAST MONTH THAT THE JAM ON THE SAINT JOHN IS POSSIBLY
SEVERAL MILES LONG. THE JAM ON THE PISCATAQUIS IS ALSO QUITE LARGE
AT NEARLY A MILE LONG. ALL OF THESE JAMS ARE STILL WELL FROZEN IN
PLACE AND ARE NOT EXPECTED TO MOVE IN THE NEXT SEVERAL DAYS. WITH
THE COPIOUS AMOUNTS OF SNOW STILL COVERING THE GROUND, THE RAIN
THAT IS FORECAST TO FALL OVER THE NEXT WEEK SHOULD GENERALLY BE
ABSORBED AND NOT RESULT IN TOO MUCH RUNOFF. HOWEVER, SHOULD A
PROLONGED WARM UP OCCUR, ESPECIALLY ACCOMPANIED BY SIGNIFICANT
RAINFALL, THESE EXISTING JAMS WILL LIKELY SERVE AS A FOCUS FOR
ADDITIONAL JAMMING AND POTENTIAL FLOODING. THE ICE IS VERY STRONG
AND WHILE IT WILL TAKE MAJOR RIVER RISES TO BREAK IT UP, IT WILL
BE MORE SUSCEPTIBLE TO CAUSING JAMMING ONCE IT DOES RELEASE.

FURTHER SOUTH, ICE JAMS REMAIN IN PLACE ON THE PENOBSCOT RIVER IN
WINN AND ON THE KENDUSKEAG STREAM THROUGH BANGOR. AS MENTIONED
ABOVE, THE ICE IS ROTTING ON THESE RIVERS AND ICE MOVEMENT IS
POSSIBLE AT ANY TIME. IN FACT, THE RIVER GAGE ON THE KENDUSKEAG
STREAM UPSTREAM OF BANGOR HAS BEEN SHOWING SIGNS OF ICE MOVEMENT
OVER THE PAST 48 HOURS.

...IN CONCLUSION...

BASED ON THE AFOREMENTIONED INFORMATION, THE WINTER/SPRING FLOOD
POTENTIAL IS ABOVE NORMAL ACROSS OUR FORECAST AREA. ALTHOUGH
RIVER FLOWS AND GROUNDWATER LEVELS ARE GENERALLY NEAR TO BELOW
NORMAL AND SOIL MOISTURE STATES ARE NEAR TO JUST ABOVE NORMAL,
SNOW DEPTHS AND THE AMOUNT OF WATER CONTAINED IN THE PACK ARE
BOTH RUNNING WELL ABOVE NORMAL FOR EARLY APRIL. THE LOW PRESSURE
SYSTEMS THAT WILL AFFECT THE AREA THIS WEEKEND AND EARLY NEXT WEEK
WILL ONLY ADD TO THE SNOWPACK`S WATER. WITH COLDER-THAN-NORMAL
WEATHER EXPECTED TO LINGER, IT IS LIKELY THAT WE WILL HEAD INTO
MID APRIL SPRING WITH A DEEPER THAN NORMAL AND VERY WATER-LADEN
SNOWPACK. THIS MEANS WE`LL HAVE INCREASED CHANCES FOR FLOODING,
ESPECIALLY IF WE EXPERIENCE A SUDDEN PATTERN CHANGE AND WARM UP.

THE POTENTIAL FOR FLOODING DUE TO ICE JAMS IS ABOVE NORMAL ACROSS
THE REGION. THE EXCEPTION LIES ALONG THE IMMEDIATE COAST WHERE
WATERWAYS GENERALLY HAVE NEAR NORMAL ICE COVER. AWAY FROM THE
COAST, ICE THICKNESSES ARE 2 TO 3 FEET IN NORTHERN AND CENTRAL
WATERWAYS. ALL INDICATIONS ARE THAT THE ICE IN THESE AREAS HAS A
LOT OF STRUCTURAL INTEGRITY. ALTHOUGH THE ICE WILL GRADUALLY
WEAKEN FROM HERE ON OUT, THE ICE WILL LIKELY REMAIN MOSTLY INTACT
UNTIL FLOWS INCREASE FROM SUBSTANTIAL SNOWMELT AND/OR A HEAVY
RAIN EVENT. IN ADDITION, SEVERAL ICE JAMS STILL REMAIN LOCKED IN
PLACE AND COULD VERY WELL SERVE AS FOCUS POINTS FOR ADDITIONAL
JAMMING AND POTENTIAL FLOODING. FURTHER SOUTH, THE PENOBSCOT AND
ITS TRIBUTARIES SUCH AS THE MATTAWAMKEAG ARE SHOWING SIGNS OF ICE
ROT. THIS MEANS THAT THE ICE COULD VERY WELL MOVE AT ANY TIME. WITH
ALL THIS IN MIND, THERE IS A HIGHER THAN NORMAL LIKELIHOOD FOR ICE
JAM PROBLEMS ACROSS THE REGION THIS SPRING.

IT IS IMPORTANT TO REMEMBER THAT VERY HEAVY RAINFALL CAN BRING
FLOODING AT ANY TIME OF THE YEAR, EVEN IN AREAS THAT HAVE LITTLE
OR NO SNOW ON THE GROUND.

THE NEXT WINTER/SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED BY
NWS CARIBOU ON THURSDAY, APRIL 17, 2014.

$$

HASTINGS







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