Flood Potential Outlook
Issued by NWS Caribou, ME

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
1220 AM EDT FRI APR 15 2016


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

THIS IS THE EIGHTH SPRING FLOOD POTENTIAL OUTLOOK FOR 2016,
ISSUED BY THE NATIONAL WEATHER SERVICE IN CARIBOU, MAINE. THIS
OUTLOOK IS FOR NORTHERN, CENTRAL AND DOWNEAST MAINE FOR THE TWO-
WEEK PERIOD FROM APRIL 14 THROUGH APRIL 28, 2016.

THE SPRING FLOOD POTENTIAL FOR OPEN WATER FLOODING IS NEAR NORMAL
ACROSS NORTHERN MAINE, INCLUDING THE AROOSTOOK, SAINT JOHN, AND
ALLAGASH RIVER BASINS. ELSEWHERE, THE FLOOD POTENTIAL IS BELOW
NORMAL.

THE POTENTIAL FOR FLOODING DUE TO ICE JAMS IS NEAR NORMAL ACROSS
NORTHERN MAINE, MAINLY ALONG THE SAINT JOHN AND ALLAGASH RIVERS.
CENTRAL AND SOUTHERN PORTIONS OF OUR AREA NO LONGER HAVE A THREAT
OF ICE JAMS.

...CLIMATOLOGICAL GUIDANCE...

THE ACTIVE WEATHER PATTERN THAT WE SAW THROUGH MARCH HAS CONTINUED
INTO THE FIRST HALF OF APRIL. A DEEPENING UPPER LEVEL TROUGH
ACROSS THE NORTHEASTERN UNITED STATES ALLOWED SEVERAL DISTURBANCES
TO CROSS THE REGION, BRINGING PERIODS OF RAIN AND SNOW. COLDER AIR
DOMINATED AS WELL, RESULTING IN MOST LOCATIONS AVERAGING 3 TO 4
DEGREES COOLER THAN NORMAL THROUGH THE MIDDLE OF THE MONTH.

WE WILL GET A RESPITE FROM THE ACTIVE AND COOLER WEATHER PATTERN
IN IMMEDIATE NEAR TERM, SPECIFICALLY THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK. A RIDGE OF HIGH PRESSURE HAS BECOME ESTABLISHED
ACROSS THE NORTHEAST AND IT WILL KEEP ITS HOLD OVER THE NEXT FEW
DAYS. AS SUCH, DRY AND VERY MILD WEATHER IS EXPECTED. TEMPERATURES
WILL REACH WELL INTO THE 50S ON SATURDAY AND MANY SPOTS WILL EVEN
TOP 60 ON SUNDAY AND MONDAY.

THE NEXT CHANCE FOR PRECIPITATION ARRIVES ON MONDAY AS A COLD
FRONT WILL CROSS OUT OF CANADA AND PUSH SOUTH THROUGH THE PINE
TREE STATE. MOISTURE WILL BE LIMITED WITH THIS BOUNDARY, WITH
PERHAPS A QUARTER TO A HALF INCH OF PRECIPITATION. SOME OF THIS
COULD FALL AS SNOW IN NORTHERN MAINE THOUGH LITTLE TO NO
ACCUMULATION IS ANTICIPATED. UNSETTLED WEATHER COULD CONTINUE INTO
THE MIDDLE OF THE WEEK BUT A BRIEF RETURN OF HIGH PRESSURE LOOKS
LIKELY TOWARD THE END OF THE WEEK.

IT`S A BIT MORE UNCERTAIN HEADING INTO WEEK TWO AS THE LONG RANGE
FORECAST MODELS ARE HAVING A HARD TIME AGREEING ON THE DETAILS
ASSOCIATED WITH A CUTOFF UPPER LOW OVER EASTERN CANADA.

AT THIS TIME, THE OFFICIAL 6 TO 10 DAY FORECAST FOR APRIL 20-24
CALLS FOR COOLER THAN NORMAL TEMPERATURES AND DRIER THAN NORMAL
CONDITIONS. AS WE HEAD LATER INTO THE MONTH, THE 8 TO 14 DAY
OUTLOOK FOR APRIL 22-28 INDICATES DRIER THAN NORMAL CONDITIONS
WHILE THERE IS NO STRONG SIGNAL FOR EITHER WARMER OR COOLER
TEMPERATURES.

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

THE SNOW PACK CONTINUES TO HOLD ON ACROSS NORTHERN MAINE THOUGH
IT HAS FINALLY BEGUN TO SHRINK IN EARNEST. MUCH OF EASTERN
AROOSTOOK COUNTY IS DOWN TO A TRACE OR SO; MANY FIELDS ARE BARE
WHILE SOME DEEPER PATCHES LINGER IN SHELTERED OR WOODED SPOTS. THE
SNOW INCREASES AS ONE HEADS NORTH AND WEST; THE UPPER SAINT JOHN
VALLEY AND ALLAGASH RIVER BASIN ARE STILL REPORTING 18 TO 30
INCHES OF SNOW. MUCH OF EASTERN AROOSTOOK IS NEAR TO BELOW NORMAL
FOR SNOW PACK, WHILE THE NORTH WOODS ARE RUNNING A BIT ABOVE
NORMAL FOR MID APRIL.

THE SNOW WATER EQUIVALENT, OR THE AMOUNT OF WATER CONTAINED IN THE
SNOW PACK, IS ALSO NEAR TO A BIT ABOVE NORMAL ACROSS THE NORTHWEST.
THERE IS 3 TO 6 INCHES OF WATER CONTAINED IN THE SNOW COVER HERE,
WITH LOCALLY HIGHER AMOUNTS. THE SNOW WATER EQUIVALENT DECREASES
SHARPLY TO THE SOUTH AND EAST, WITH AN INCH OR LESS ACROSS MUCH OF
EASTERN AROOSTOOK COUNTY AND PARTS OF NORTHERN PENOBSCOT AND
PISCATAQUIS COUNTIES.

AS PER THE LATEST REPORTS, THERE IS LITTLE TO NO CONSISTENT SNOW
COVER SOUTH OF A LINE ROUGHLY FROM HOULTON TO GREENVILLE.

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

THE ACTIVE WEATHER PATTERN THAT WE`VE EXPERIENCED OVER THE PAST
SEVERAL WEEKS, ALONG WITH PERIODS OF SNOWMELT, HAVE KEPT NEAR-
SURFACE SOIL MOISTURE STATES WETTER THAN NORMAL ACROSS THE CARIBOU
FORECAST AREA. LOOKING AT THE LONGER TERM SOIL CONDITIONS, THE
LATEST PALMER DROUGHT SEVERITY INDEX FROM APRIL 9 ALSO CONTINUED
TO SHOW MOIST TO VERY MOIST CONDITIONS ACROSS THE ENTIRE AREA. AS
WOULD BE EXPECTED, GROUNDWATER LEVELS ARE ABOVE NORMAL AS WELL. IN
FACT, THE WELL AT CALAIS IS AT THE HIGHEST MEDIAN OF A 36-YEAR
PERIOD OF RECORD FOR THIS TIME OF YEAR.

...RIVER AND ICE CONDITIONS...

RIVER FLOWS HAVE FLUCTUATED OVER THE PAST COUPLE OF WEEKS OWING TO
SEVERAL RAIN EVENTS. THIS IS ESPECIALLY TRUE ALONG THE CENTRAL AND
SOUTHERN RIVER BASINS, MANY OF WHICH EXPERIENCED PEAK FLOWS APRIL
9-11 AFTER A SYSTEM DROPPED 1-2 INCHES OF RAIN. NORTHERN WATERWAYS
HAVE HAD MAINLY AN OVERALL DOWNWARD TREND IN FLOW, THOUGH THERE
HAVE BEEN SOME MODEST INCREASES RECENTLY DUE TO SNOWMELT.

THE ICE STARTED TO GO OUT ON THE AROOSTOOK RIVER EARLY IN APRIL,
FIRST IN THE LOWER REACHES NEAR FORT FAIRFIELD ON THE 2ND INTO THE
3RD. A BRIEF ICE JAM JUST UPSTREAM OF FORT FAIRFIELD DID RESULT IN
GRIMES ROAD BEING CLOSED FOR A TIME. IT TOOK ANOTHER WEEK FOR THE
ICE COVER TO BREAK UP FURTHER UPSTREAM, AND THE RIVER FINALLY
FLUSHED OUT ON APRIL 10TH. THE ICE JAMMED UP FROM TIME TO TIME AS
IT HEADED FROM WASHBURN DOWN THROUGH FORT FAIRFIELD, BUT OUTSIDE
OF SOME MINOR FIELD FLOODING, NO SIGNIFICANT ISSUES WERE NOTED.

MEANWHILE, THE ALLAGASH RIVER AND PORTIONS OF THE UPPER SAINT JOHN
CONTINUE TO HOLD ONTO ICE COVER. THE MAIN CONCERN CONTINUES TO BE
A 4-MILE LONG ICE JAM THAT LIES NEAR THE SAINT FRANCIS/ALLAGASH
LINE. THIS JAM SEEMS TO HAVE BECOME GROUNDED AND WILL LIKELY
REQUIRE SOME GOOD RIVER RISES TO BE MOVED. ANOTHER SMALL JAM WAS
SEEN IN ALLAGASH. BELOW THE LARGE ALLAGASH JAM, SHEET ICE
STRETCHED FROM SAINT FRANCIS DOWN THROUGH SAINT JOHN, THOUGH
THERE WERE SOME OPEN STRETCHES. SHEET ICE ALSO COVERS THE LOWER
ALLAGASH. SOME ICE MOVEMENT HAS BEEN NOTED ON BOTH THE ALLAGASH
AND SAINT JOHN RIVERS IN THE VICINITY OF ALLAGASH, BUT THE JAMS
REMAIN IN PLACE. DOWNSTREAM, THE SAINT JOHN LOOKS TO BE ICE FREE
FROM FORT KENT DOWN THROUGH GRAND ISLE, WHERE A SMALL ICE JAM HAS
COLLECTED ON THE EXISTING SHEET ICE. THIS ICE COVER THEN EXTENDS
DOWN THROUGH VAN BUREN AND HAMLIN.

ALL OTHER RIVERS ARE ICE FREE AT THIS TIME.

...IN CONCLUSION...

BASED ON THE AFOREMENTIONED INFORMATION, THE WINTER/SPRING FLOOD
POTENTIAL FOR OPEN WATER FLOODING FOR THE NEXT TWO WEEKS IS NEAR
NORMAL ACROSS NORTHERN MAINE. THIS INCLUDES THE AROOSTOOK, SAINT
JOHN, AND ALLAGASH BASINS. THESE RIVERS ARE RUNNING RELATIVELY
HIGH. WHILE NO SIGNIFICANT RAIN EVENTS ARE ANTICIPATED IN THE NEAR
TERM, THERE IS STILL PLENTY OF SNOW AVAILABLE FOR MELT, ESPECIALLY
IN THE UPPER REACHES OF THESE RIVERS. WITH VERY WARM TEMPERATURES
EXPECTED THROUGH THE WEEKEND, THIS MELT AND RESULTANT RUNOFF WILL
KEEP FLOWS HIGH.

ACROSS THE REMAINDER OF OUR FORECAST AREA, THERE IS LITTLE TO NO
SNOW PACK LEFT AND SINCE WE DO NOT EXPECT ANY HEAVY RAIN EVENTS
OVER THE NEXT SEVERAL DAYS, A BELOW NORMAL FLOODING THREAT SEEMS
REASONABLE.

THE THREAT FOR ICE JAMS IS MAINLY LIMITED TO THE SAINT JOHN AND
ALLAGASH RIVERS AND IS NEAR NORMAL FOR MID APRIL. THERE ARE
CURRENTLY ICE JAMS SITTING IN AND NEAR ALLAGASH, BUT THESE SEEM TO
BE WELL LOCKED INTO PLACE AT THIS TIME. IT WILL LIKELY TAKE A
FAIRLY SIGNIFICANT RIVER RISE TO CAUSE THESE TO MOVE, ESPECIALLY
THE LARGE ONE. AT THIS TIME, MINIMAL INCREASES IN FLOW ARE
EXPECTED SINCE NO PRECIPITATION IS FORECAST IN THE NEAR TERM. IN
THE MEANTIME, THE STRONG APRIL SUN WILL CONTINUE TO WEAKEN THE
ICE. WE ARE ALREADY SEEING MOVEMENT OF SOME OF THE SHEET ICE NEAR
THESE JAMS, BUT IT TOO HAS LIKELY BEEN ROTTING AS IT SAT IN PLACE.
BREAK UP OF THIS ICE IS POSSIBLE THROUGH THE WEEKEND, WHICH MAY
RESULT IN FLOODING IF IT COLLECTS ON THE ALREADY EXISTING ICE
JAMS. IF THE LARGE JAM CAN GET MOVING, IT VERY WELL COULD CAUSE
FLOODING IF IT COLLECTS ELSEWHERE DOWNSTREAM. BUT WITH OPEN WATER
STRETCHING FROM FORT KENT ALL THE WAY TO GRAND ISLE, IT IS HOPED
THAT THE ICE WILL HAVE ROTTED ENOUGH TO SIMPLY FLUSH OUT.

IT IS IMPORTANT TO REMEMBER THAT VERY HEAVY RAINFALL CAN BRING
FLOODING AT ANY TIME OF THE YEAR, EVEN IN AREAS THAT DON`T HAVE A
SIGNIFICANT SNOWPACK.

UNLESS CONDITIONS WARRANT ANOTHER ISSUANCE, THIS WILL BE THE
FINAL SPRING FLOOD POTENTIAL OUTLOOK FOR THE 2016 SEASON.

$$

HASTINGS



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