National Weather Service Text Product Display

Flood Potential Outlook
Issued by NWS Caribou, ME
Versions: 1 2 3
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FGUS71 KCAR 190951
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MEC003-009-019-021-029-192200-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
551 AM EDT FRI APR 19 2013

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

THIS IS THE NINTH WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR
2013...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 18 THROUGH
MAY 2, 2013.

THE WINTER/SPRING FLOOD POTENTIAL FOR FAR NORTHWEST MAINE IS
SLIGHTLY ABOVE NORMAL, WHILE THE SPRING FLOOD THREAT FOR THE
REMAINDER OF NORTHERN AND EASTERN MAINE IS NORMAL.

THE POTENTIAL FOR FLOODING DUE TO ICE JAMS HAS GENERALLY ENDED FOR
MUCH OF THE REGION. THE EXCEPTION IS ALONG THE FAR NORTHERN RIVERS
INCLUDING THE ALLAGASH, BIG BLACK, AND UPPER REACHES OF THE SAINT
JOHN. THERE IS STILL SOME ICE ON THESE WATERWAYS SO THE POTENTIAL
FOR ICE JAM DEVELOPMENT STILL EXISTS. HOWEVER, SIGNIFICANT JAMS
ARE NOT CONSIDERED LIKELY.

...CLIMATOLOGICAL GUIDANCE...

THE BLOCKING RIDGE OVER GREENLAND THAT HAS DOMINATED THE WEATHER
PATTERN OVER THE NORTHEASTERN UNITED STATES FOR THE PAST COUPLE OF
MONTHS IS FINALLY SHOWING SIGNS OF BREAKING DOWN. THIS MEANS A
TURN TOWARD MILDER CONDITIONS AS THE JET STREAM SHIFTS BACK NORTH,
ESPECIALLY OVER THE NEXT WEEK. THEREAFTER, THE PATTERN BECOMES
MORE CONDUCIVE FOR TROFINESS, RESULTING IN TEMPERATURES DROPPING
BACK TO NORMAL. IN ADDITION, THE ACTIVE PATTERN WE HAVE BEEN
EXPERIENCING LOOKS TO CONTINUE INTO LATE APRIL WITH AT LEAST TWO
FRONTAL SYSTEMS EXPECTED TO MOVE ACROSS NEW ENGLAND IN THE NEXT
6-10 DAYS.

THE OFFICIAL NATIONAL WEATHER SERVICE OUTLOOK CORRELATES WITH THIS
THINKING AS IT CALLS FOR ABOVE NORMAL TEMPERATURES AND WETTER THAN
NORMAL CONDITIONS OVER THE NEXT 1 TO 2 WEEKS. AS WE MOVE INTO
EARLY MAY, THIS PATTERN EASES A BIT, WITH BOTH PRECIPITATION AND
TEMPERATURES RUNNING CLOSE TO NORMAL.

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

COOLER-THAN-NORMAL CONDITIONS THROUGH THE FIRST HALF OF MARCH
HAVE ALLOWED THE SNOWPACK ACROSS THE WOODED HIGHER TERRAIN OF
NORTHERN AND CENTRAL MAINE TO REMAIN. IN THESE LOCATIONS, THERE IS
STILL SOME 8 TO 18 INCHES OF SNOW ON THE GROUND. ISOLATED
LOCATIONS ARE STILL REPORTING NEARLY 2 FEET OF SNOW. THIS DEEP SNOWPACK
IS ABOVE NORMAL FOR MID-APRIL. ACROSS THE LOWER ELEVATIONS, SHADY
AND/OR WOODED AREAS STILL HAVE 4 TO 8 INCHES OF SNOW ON THE GROUND
WHILE EXPOSED REGIONS ARE NEARLY DEVOID OF SNOW COVER. THESE
NUMBERS ARE BELOW NORMAL. DOWNEAST MAINE IS NOW DOWN TO BARE
GROUND.

THE SNOW WATER EQUIVALENT, OR THE AMOUNT OF WATER CONTAINED IN
THE SNOWPACK, IS ALSO ABOVE NORMAL IN NORTHWEST MAINE. SWES HERE
ARE ON THE ORDER OF 3 TO 6 INCHES, WITH OVER 9 INCHES ON NORTHEAST
FACING SLOPES. ELSEWHERE, FOR THOSE AREAS THAT HAVE SNOW, THERE IS
1 TO 3 INCHES OF WATER CONTAINED IN THE PACK.

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

THE LATEST PALMER DROUGHT SEVERITY INDEX, WHICH IS A MEASURE OF
LONG-TERM MOISTURE STATES, SHOWS NEAR OR WETTER THAN NORMAL
CONDITIONS ACROSS NORTHERN MAINE DUE TO INCREASING SNOWMELT. FOR
THE REMAINDER OF THE STATE, SOIL MOISTURE STATES ARE NEAR TO
SLIGHTLY BELOW NORMAL. GROUNDWATER LEVELS ARE NEAR NORMAL ACROSS
THE PINE TREE STATE.

...RIVER AND ICE CONDITIONS...
RIVER FLOWS HAVE BEEN INCREASING OVER THE PAST SEVERAL DAYS AS
WARMER CONDITIONS HAVE RESULTED IN SNOWMELT, THOUGH THEY ARE STILL
GENERALLY NEAR NORMAL. THE FAR UPPER REACHES OF THE SAINT JOHN ARE
EXPERIENCING SLIGHTLY HIGHER THAN NORMAL FLOWS DUE TO THE DEEP
SNOWPACK STILL COVERING THE GROUND THERE.

THE ICE JAM THREAT IS ESSENTIALLY OVER FOR NORTHERN AND EASTERN
MAINE, AS THE ICE HAS FLUSHED OUT OF MOST OF THE MAINSTEM RIVERS.
THIS INCLUDES THE AROOSTOOK, PISCATAQUIS, PENOBSCOT, AND
MATTAWAMKEAG RIVER BASINS. HOWEVER, RIVER GAUGES ALONG THE
ALLAGASH, BIG BLACK, AND UPPER SAINT JOHN RIVERS ARE STILL SHOWING
SIGNS OF ICE MOVEMENT. THIS ICE IS GENERALLY THIN AND WEAK AND
GENERALLY NOT CONDUCIVE TO CAUSING SIGNIFICANT ICE JAMS.
THEREFORE, SUBSEQUENT JAM-RELATED FLOODING DOES NOT APPEAR TO BE
LIKELY. HOWEVER, IT SHOULD BE REMEMBERED THAT ICE JAMS ARE ALWAYS
A THREAT UNTIL THE ICE IS COMPLETELY GONE. IN FACT, A WEBCAM NEAR
DAAQUAM, QUEBEC SHOWED SOME MINOR FLOODING DUE TO AN ICE JAM ON
THURSDAY, APRIL 18.

...IN CONCLUSION...

BASED ON THE AFOREMENTIONED INFORMATION, THE WINTER/SPRING FLOOD
POTENTIAL IS SLIGHTLY ABOVE NORMAL ACROSS NORTHWESTERN MAINE,
MAINLY ALONG AND WEST OF ROUTE 11.  RIVER FLOWS AND ANTECEDENT
SOIL MOISTURE STATES ARE NEAR TO SLIGHTLY ABOVE NORMAL IN THESE
AREAS AND THERE IS STILL PLENTY OF WATER HELD IN THE SNOWPACK FOR
MELT RUNOFF. MEANWHILE, THE REMAINDER OF NORTHERN AND CENTRAL
MAINE STANDS A NORMAL FLOODING THREAT. WITH MILDER CONDITIONS
EXPECTED INTO EARLY NEXT WEEK, ALONG WITH LIGHT PRECIPITATION
ASSOCIATED WITH A COUPLE OF FRONTAL PASSAGES, RIVERS IN NORTHERN
AND CENTRAL MAINE WILL CONTINUE TO SHOW SIGNIFICANT RISES OVER THE
NEXT SEVERAL DAYS. HOWEVER, IT IS RARE FOR PURE SNOWMELT TO RESULT
IN WIDESPREAD OR SIGNIFICANT FLOODING WITHOUT ADDITIONAL RUNOFF
FROM HEAVY RAINFALL. THIS IS ESPECIALLY TRUE NOW THAT MOST RIVERS
ARE NOW MOSTLY ICE FREE. THAT BEING SAID, THE SPRING FLOOD THREAT
HAS NOT COMPLETELY PASSED IN NORTHERN AND CENTRAL MAINE. WHILE NO
FLOODING IS CURRENTLY ANTICIPATED, NORTHERN AND CENTRAL WATERWAYS
WILL HAVE TO BE WATCHED CLOSELY, ESPECIALLY THOSE IN THE UPPER
SAINT JOHN RIVER BASIN.

FOR THOSE AREAS WITH VERY LITTLE TO NO SNOW COVER, ESPECIALLY
FROM BANGOR SOUTH, THE SPRING FLOOD THREAT HAS PASSED. THIS
INCLUDES THE THREAT FROM ICE JAMS, AS THESE WATERWAYS ARE ICE
FREE.

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

UNLESS CONDITIONS CHANGE DRASTICALLY, THIS WILL MOST LIKELY BE THE
LAST WINTER/SPRING FLOOD POTENTIAL OUTLOOK ISSUED THIS SEASON. IF
ANOTHER OUTLOOK IS DEEMED NECESSARY, IT WILL BE ISSUED BY THE
NATIONAL WEATHER SERVICE CARIBOU OFFICE ON MAY 2, 2013.

$$

HASTINGS
National Weather Service Weather Forecast Office
