Flood Potential Outlook
Issued by NWS Portland, ME

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FGUS71 KGYX 162052
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MEC001-005-007-011-013-015-017-023-025-027-031-NHC001-003-005-007-
009-011-013-015-017-019-182100-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE GRAY ME
452 PM EDT THU APR 16 2015

...WINTER/SPRING FLOOD POTENTIAL OUTLOOK...

THE FLOOD POTENTIAL FOR THE CONNECTICUT RIVER... NORTHERN AND
CENTRAL NEW HAMPSHIRE AND WESTERN MAINE IS ABOVE NORMAL. THE
FLOOD POTENTIAL FOR SOUTHEAST NEW HAMPSHIRE IS NORMAL. THE THREAT
OF FLOODING DUE TO ICE JAMS HAS PASSED FOR THE SEASON.

THIS IS THE NINTH IN A SERIES OF REGULARLY SCHEDULED HYDROLOGIC
OUTLOOKS ISSUED DURING THE WINTER AND SPRING SEASONS. THESE
OUTLOOKS WILL BE ISSUED EVERY TWO WEEKS UNTIL THE END OF THE SNOW
MELT SEASON... AND WILL ASSESS THE POTENTIAL FOR FLOODING BASED A
NUMBER OF FACTORS.

...CLIMATOLOGICAL GUIDANCE...

OVER THE LAST WEEK OR SO TEMPERATURES HAVE CLIMBED TO ABOVE NORMAL
LEVELS WHICH HAS PROMOTED SNOWMELT. AT THE SAME TIME PRECIPITATION
HAS BEEN BELOW NORMAL FOR THE MONTH OF APRIL. PRECIPITATION DEPARTURES
ARE RUNNING 0.75 TO 1.5 INCHES BELOW NORMAL. THIS HAS HELPED TO
SLOWLY MELT AWAY THE SNOWPACK. MEDIUM RANGE MODELS INDICATE THAT
THIS OVERALL PATTERN WILL BEGIN TO CHANGE WITH COOLER THAN NORMAL
TEMPERATURES AND ABOVE NORMAL PRECIPITATION. IN FACT THE NEXT 2
WEEKS HAVE THE POTENTIAL TO BE STORMY AND QUITE WET.

THE OFFICIAL 6 TO 10 DAY AND 8 TO 14 DAY NATIONAL WEATHER SERVICE
FORECAST CALLS FOR BELOW NORMAL TEMPERATURES AND ABOVE NORMAL
PRECIPITATION.

...OBSERVED SNOW DEPTH AND WATER EQUIVALENT...

...NEW HAMPSHIRE...

ACROSS SOUTHERN NEW HAMPSHIRE THE GROUND IS MOSTLY BARE. HOWEVER
SNOW REMAINS IN THE HIGHER ELEVATIONS OF THE MONADNOCKS WHERE
SNOW DEPTH RANGES FROM 1 TO 8 INCHES IN WOODED AREA. FARTHER NORTH
FROM THE WHITE MOUNTAINS TO THE CANADIAN BORDER ABOVE 1500 FEET
SNOW DEPTH IS STILL IN THE 1 TO 2 FOOT RANGE IN WOODED AREA. A
SNOW SURVEY REPORT BY THE CORPS OF ENGINEERS AT 1950 FEET NEAR
CANNON MOUNTAIN REPORTED 26 INCHES OF SNOW ON THE GROUND ON APRIL
14. A SNOW SURVEY DONE ON APRIL 15 BY TRANSCANADA REPORTED A SNOW
DEPTH OF 33 INCHES AT MOOSE FALLS ALSO AT 1950 FEET.

SNOW WATER EQUIVALENT IN THE HIGHER TERRAIN OF THE MONADNOCKS
RANGES FROM 1 TO 3 INCHES. FARTHER NORTH FROM THE WHITE MOUNTAINS
TO THE CANADIAN BORDER SNOW WATER EQUIVALENT RANGES FROM 2 TO 5 INCHES
ABOVE 1500 FEET. ABOVE ABOUT 2000 FEET SNOW WATER EQUIVALENT
CLIMBS TO 4 TO 9 INCHES WITH LOCALLY HIGHER AMOUNTS ABOVE 2500
FEET. NEAR CANNON MOUNTAIN THE 26 INCHES OF SNOW MEASURED THERE
HAD 9.2 INCHES OF SNOW WATER EQUIVALENT IN IT. AT MOOSE FALLS THE
33 INCHES OF SNOW MEASURED THERE HAD 10.8 INCHES OF WATER
EQUIVALENT IN IT.

SNOW WATER EQUIVALENT IS ABOVE NORMAL FOR THE TIME OF YEAR.

...WESTERN MAINE...

THE GROUND IS NOW BARE IN YORK AND CUMBERLAND COUNTY. FROM
INTERIOR SOUTHERN MAINE TO THE FOOTHILLS SNOW DEPTH RANGES FROM 1
TO 12 INCHES IN WOODED AREAS. FROM THE MOUNTAINS TO THE CANADIAN
BORDER SNOW DEPTH RANGES FROM 12 TO 24 INCHES WITH LOCAL AMOUNTS
TO 30 INCHES.

SNOW WATER EQIUIVALENT FROM INTERIOR SOUTHERN MAINE TO THE
FOOTHILLS RANGES FROM A TRACE TO 4 INCHES. FROM THE MOUNTAINS
TO THE CANADIAN BORDER SNOW WATER EQUIVALENT RANGES FROM 4 TO 9
INCHES. SNOW WATER EQUIVALENT IS NEAR NORMAL IN THE MOUNTAINS AND
FOOTHILLS BUT IS ABOVE NORMAL FROM AUGUSTA AND POINTS EAST.

THE SNOWPACK IS RIPE THOUGHOUT MAINE AND NEW HAMPSHIRE WITH
DENSITIES MOSTLY ABOVE 35 PERCENT. A RIPE SNOWPACK NO LONGER HAS
THE ABILITY TO RETAIN RAINFALL AND WOULD RELEASE WATER DURING A
RAIN EVENT. THE DENSITY OF THE SNOWPACK IN THE MOUNTAINS IS STILL
LESS THAN 30 PERCENT.

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

SOIL MOISTURE ANOMALY MAPS FROM APRIL 4 INDICATE NEAR NORMAL SOIL
MOISTURE ACROSS WESTERN MAINE AND BELOW NORMAL SOIL MOISTURE IN
NEW HAMPSHIRE.

THE PALMER DROUGHT SEVERITY INDEX FOR APRIL 11 WHICH INDICATES
LONGER TERM MOISTURE CONDITIONS SHOWS NEAR NORMAL MOISTURE FOR ALL
OF NEW HAMPSHIRE AND MAINE.

THE USGS REPORTS THAT GROUNDWATER LEVELS ARE GENERALLY BELOW
NORMAL HOWEVER MOST ARE NOW RISING AS THE SNOWMELT HAS BEGUN.
RESERVOIRS IN THE ANDROSCOGGIN RIVER BASIN ARE 35.7 PERCENT FULL
WHICH IS 6.6 PERCENT BELOW NORMAL. IN THE KENNEBEC BASIN
MOOSEHEAD... FLAGSTAFF AND BRASSUA LAKES ARE BELOW NORMAL LEVELS
FOR THE TIME OF YEAR. THE RESERVOIRS IN BOTH THE ANDROSCOGGIN AND
KENNEBEC RIVER BASINS HAVE SUFFICIENT ROOM TO HELP CATCH THE MELT
WATER THIS SPRING.

WATER SUPPLY SHORTAGES ARE NOT ANTICIPATED.

...RIVER AND ICE CONDITIONS...

RIVER FLOWS HAVE BEEN RISING NOW DUE TO THE WARM TEMPERATURES AND
SNOWMELT. RIVER LEVELS IN MAINE AND NEW HAMPSHIRE ARE NORMAL TO
ABOVE NORMAL FOR THE TIME OF YEAR.

RIVERS IN WESTERN MAINE AND NEW HAMPSHIRE ARE NOW MOSTLY FREE OF
ICE.

...IN CONCLUSION...

BASED ON THE ABOVE INFORMATION...THE WINTER/SPRING FLOOD
POTENTIAL ACROSS WESTERN MAINE... THE CONNECTICUT RIVER AND
CENTRAL AND NORTHERN NEW HAMPSHIRE IS ABOVE NORMAL. THE FLOOD
POTENTIAL FOR SOUTHEAST NEW HAMPSHIRE IS NORMAL.

WITH RIVERS NOW ELEVATED DUE TO RECENT SNOWMELT AND AN EXTENDED PERIOD
OF UNSETTLED WEATHER POSSIBLE ALONG WITH A SUBSTANTIAL SNOWPACK
IN THE MOUNTAINS THE CHANCES OF SPRINGTIME FLOODING ARE
INCREASING.

IT IS IMPORTANT TO NOTE THAT MAJOR FLOODING DOES NOT OCCUR
FROM SNOW MELT ALONE. RAINFALL...HOW MUCH AND IN HOW SHORT A
PERIOD OF TIME...IS THE MOST IMPORTANT FACTOR IN DETERMINING THE
SEVERITY OF FLOODING.

ANOTHER WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED BY 8 AM FRIDAY
MAY 1 OR SOONER IF NEEDED.

$$

TFH



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