Flood Potential Outlook
Issued by NWS Portland, ME

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FGUS71 KGYX 121919
ESFGYX
MEC001-005-007-011-013-015-017-023-025-027-031-NHC001-003-005-007-
009-011-013-015-017-019-141930-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE GRAY ME
319 PM EDT THU MAR 12 2015

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

THE SHORT TERM /NEXT 2 WEEKS/ FLOOD POTENTIAL FOR WESTERN MAINE
AND NEW HAMPSHIRE IS NORMAL. THE LONGER TERM FLOOD POTENTIAL IS
ABOVE NORMAL. THE SHORT TERM /NEXT 2 WEEKS/ POTENTIAL FOR FLOODING
DUE TO ICE JAMS IS NORMAL. THE LONGER TERM ICE JAM FLOOD POTENTIAL
IS ABOVE NORMAL.

THIS IS THE SIXTH 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...

AFTER A VERY COLD FEBRUARY AND A COLD FIRST WEEK OF MARCH... WESTERN
MAINE AND NEW HAMPSHIRE HAVE SEEN THE JET STREAM RETREAT TO THE
NORTH AT LEAST TEMPORARILY. THIS ALLOWED FOR SOME MILD WEATHER TO
MOVE INTO THE REGION OVER THE LAST 3 DAYS. HOWEVER IT IS BACK TO
REALITY AS COLD ARCTIC AIR HAS ONCE AGAIN MOVED IN OVER NORTHERN
NEW ENGLAND. THE LONGER RANGE CLIMATIC GUIDANCE SUGGEST THAT THE
COLDER AIR WILL REMAIN OVER THE NORTHEAST THROUGH THE REMAINDER
OF MARCH. A RIDGE WILL ONCE AGAIN SETUP IN THE WEST WITH A TROUGH
IN THE NORTHEAST. THE STORM TRACK WILL IN GENERAL BE FROM
NORTHWEST TO SOUTHEAST WITH QUICK MOVING CLIPPER TYPE SYSTEMS
MOVING THROUGH THE AREA. THIS WILL LIMIT PRECIPITATION.

THE OFFICIAL NATIONAL WEATHER SERVICE 6 TO 10 DAY AND 8 TO 14 DAY
FORECAST INDICATES BELOW NORMAL TEMPERATURES WITH NEAR TO BELOW
NORMAL PRECIPITATION.

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

...NEW HAMPSHIRE...

SNOW DEPTH ACROSS NEW HAMPSHIRE IS GENERALLY 1 TO 2 FEET WITH
AMOUNTS OF 2 TO 3 FEET COMMON AT ELEVATIONS ABOVE 2000. SNOW
DEPTH IS A BIT LESS IN THE CONNECTICUT RIVER VALLEY ON THE ORDER
OF 6 TO 12.

SNOW WATER EQUIVALENT IS GENERALLY IN THE 4 TO 8 INCH RANGE
ACROSS NEW HAMPSHIRE WITH LOCALLY HIGHER AMOUNTS OF 8 TO 10
INCHES ABOVE 2000 FEET.

SNOW DEPTH AND SNOW WATER EQUIVALENT ARE ABOVE NORMAL IN SOUTHEAST
NEW HAMPSHIRE. FOR THE REMAINDER OF THE STATE SNOW WATER
EQUIVALENT IS NEAR NORMAL

...WESTERN MAINE...

SNOW DEPTH IN WESTERN MAINE RANGES FROM 1 TO 3 FEET WITH LOCALLY
HIGHER AMOUNTS.

SNOW WATER EQUIVALENT GENERALLY RANGES FROM 5 TO 8 INCHES WITH
LOCAL AMOUNTS OF 8 TO 10 INCHES.

SNOW WATER EQUIVALENT IS NEAR NORMAL WITH THE EXCEPTION OF
SOUTHERN AND COASTAL LOCATIONS WHERE IT IS WELL ABOVE NORMAL.

THE DENSITY OF THE SNOWPACK IS GENERALLY IN THE 25 TO 30 PERCENT
RANGE. A SNOWPACK IS CONSIDERED RIPE ONCE THE DENSITY REACHES NEAR
40 PERCENT. A RIPE SNOWPACK NO LONGER HAS THE ABILITY TO RETAIN
RAINFALL AND WOULD RELEASE WATER DURING A RAIN EVENT.

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

SOIL MOISTURE ANOMALY MAPS FROM MARCH 11 INDICATE NEAR NORMAL
SOIL MOISTURE ACROSS WESTERN MAINE AND ALL OF NEW HAMPSHIRE.

THE PALMER DROUGHT SEVERITY INDEX WHICH INDICATES LONGER TERM
MOISTURE CONDITIONS SHOWS NEAR NORMAL MOISTURE FOR NORTHERN NEW
HAMPSHIRE AND NORTHERN MAINE. FOR CENTRAL AND COASTAL LOCATIONS
THE PDSI IS UNUSUALLY MOIST TO VERY MOIST DUE TO THE FACT THAT
MORE PRECIPITATION HAS FALLEN IN THESE LOCATIONS OVER THE PAST
FEW WEEKS.

THE USGS REPORTS THAT GROUNDWATER LEVELS ARE MOSTLY IN THE NORMAL
RANGE FOR THE TIME OF YEAR. RESERVOIRS IN THE ANDROSCOGGIN RIVER
BASIN ARE 47.3 PERCENT FULL WHICH IS 9.3 PERCENT ABOVE NORMAL.
RESERVOIRS IN THE KENNEBEC RIVER BASIN ARE ALSO ABOVE NORMAL
LEVELS FOR THE TIME OF YEAR WITH THE EXCEPTION OF MOOSEHEAD LAKE
WHICH IS ABOUT NORMAL.

WATER SUPPLY SHORTAGES ARE NOT ANTICIPATED.

...RIVER AND ICE CONDITIONS...

RIVER FLOWS REMAIN NEAR NORMAL FOR THE TIME OF YEAR. MOST RIVERS
AND STREAMS ARE ICE COVERED. RECENT ICE MEASUREMENTS BY THE USGS
INDICATE THAT ICE IS GENERALLY 12 TO 24 INCHES THICK WITH 1 TO 2
FEET OF SNOW ON TOP OF THE ICE. ICE THICKNESS HAS NOT INCREASED
MUCH SINCE LATE JANUARY DUE TO THE AMOUNT OF SNOW COVER WHICH IS
INSULATING THE ICE COVER AND PREVENTING IT FROM THICKENING. AN
ICE JAM REMAINS IN PLACE ON THE KENNEBEC RIVER IN THE VICINITY OF
MADISON. WATER LEVELS HAVE DECREASED SIGNIFICANTLY BEHIND THIS JAM
AS THE COLD WEATHER AND LACK OF RUNOFF HAVE SEEN RIVER FLOWS
LOWER. THIS JAM WILL REMAIN IN PLACE AND MAY POSE A RISK LATER IN
THE SPRING.

...IN CONCLUSION...

BASED ON THE ABOVE INFORMATION...THE WINTER/SPRING FLOOD
POTENTIAL ACROSS WESTERN MAINE AND NEW HAMPSHIRE IS NORMAL IN THE
SHORT TERM /NEXT 2 WEEKS/ BUT ABOVE NORMAL IN THE LONG TERM. THIS
IS DUE TO THE FACT THAT OVER THE NEXT 2 WEEKS PRECIPITATION IS
EXPECTED TO BE MOSTLY BELOW NORMAL WITH COLDER THAN NORMAL
TEMPERATURES AND NO EXTENDED PERIODS OF WARM WEATHER EXPECTED.
HOWEVER IN THE LONGER TERM WE WILL LIKELY BE GOING INTO APRIL WITH
A SIGNIFICANT SNOWPACK AND ICE COVER. THE LATER INTO THE SPRING
SEASON WE PROGRESS WITH A SIGNIFICANT SNOWPACK THE GREATER THE
CHANCE OF A RAPID WARM UP WITH RAIN.

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
MARCH 20.


$$

TFH



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