Flood Potential Outlook
Issued by NWS Caribou, ME

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
1223 PM EST THU FEB 4 2016

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

THIS IS THE THIRD WINTER/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 FEBRUARY 4 THROUGH FEBRUARY 18, 2016.

THE WINTER/SPRING FLOOD POTENTIAL FOR OPEN WATER FLOODING IS
BELOW NORMAL FOR ALL OF NORTHERN, CENTRAL, AND DOWNEAST MAINE.
THE POTENTIAL FOR FLOODING DUE TO ICE JAMS IS ALSO BELOW NORMAL
FOR DOWNEAST MAINE, WHILE IT IS NEAR NORMAL ACROSS NORTHERN AND
CENTRAL MAINE.

...CLIMATOLOGICAL GUIDANCE...

THE MILDER WEATHER PATTERN THAT HAS BEEN IN PLACE MUCH OF THE
PAST COUPLE OF WEEKS IS IN THE PROCESS OF CHANGING TO A MORE
WINTERLIKE ONE. A DEEPENING AND EXPANDING UPPER LEVEL TROUGH IS
EXPECTED TO SET UP ACROSS THE MIDWEST AND GRADUALLY SHIFT EAST AS
WE HEAD THROUGH NEXT WEEK. SOME OF THE FORECAST GUIDANCE IS
INDICATING THAT THIS COULD BE PERHAPS THE COLDEST AIRMASS OF THE
SEASON ACROSS SOUTHERN CANADA. THERE IS STILL UNCERTAINTY AS TO
HOW FAR SOUTH THIS COLD AIR WILL PUSH, BUT IT LOOKS LIKELY THAT
WE WILL RETURN TO AT LEAST NEAR NORMAL TEMPERATURES OVER THE NEXT
TWO WEEKS. IN ADDITION, THE WEATHER PATTERN WILL REMAIN ACTIVE,
WITH POTENTIAL STORM SYSTEMS EVERY FEW DAYS OR SO. FORECAST MODELS
ARE TRENDING FURTHER NORTH AND WEST WITH THE SYSTEM FOR FRIDAY,
AND THEY CONTINUE TO SHOW A POTENTIAL COASTAL STORM THAT COULD
AFFECT PORTIONS OF OUR AREA THE MIDDLE OF NEXT WEEK. THE OFFICIAL
NATIONAL WEATHER SERVICE 6-10 DAY FORECAST FOR FEBRUARY 9 THROUGH
17 MATCHES THE ABOVE THINKING, CALLING FOR NEAR TO SLIGHTLY BELOW
NORMAL TEMPERATURES AND NEAR NORMAL TO WETTER-THAN NORMAL
CONDITIONS DURING THIS TIME FRAME.

THE RETURN OF WINTER WILL LIKELY BE BRIEF, HOWEVER. WITH A STRONG
EL NINO REMAINING IN PLACE, THE LONGER TERM FORECAST STILL FAVORS
ABOVE NORMAL TEMPERATURES AS WE FINISH UP WINTER AND HEAD INTO
EARLY SPRING.

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

SNOW DEPTH AND THE SNOW WATER EQUIVALENT CONTINUE TO STAY WELL
BELOW NORMAL FOR THIS TIME OF YEAR. THE LOWER PENOBSCOT VALLEY AND
DOWNEAST MAINE ONLY HAVE PATCHY SNOW COVER. THE LOWER ELEVATIONS
IN THE CENTRAL HIGHLANDS HAVE ANYWHERE FROM 2 TO 8 INCHES, WHILE
THE HIGHER TERRAIN HAS 8-12 INCHES ON THE GROUND. CENTRAL AND
SOUTHERN AROOSTOOK COUNTY ARE GENERALLY COVERED WITH 6 TO 12
INCHES OF SNOW, WITH THE NORTH WOODS LIKELY BLANKETED BY 12-20
INCHES OF SNOW. THIS IS BELOW NORMAL FOR EARLY FEBRUARY. HOWEVER,
WITH AN ACTIVE WEATHER PATTERN EXPECTED OVER THE NEXT FEW WEEKS,
THE SNOWPACK WILL LIKELY DEEPEN.

THE SNOW WATER EQUIVALENT, OR THE AMOUNT OF WATER CONTAINED IN
THE SNOWPACK, IS ALSO BELOW NORMAL ACROSS THE REGION. DOWNEAST
MAINE HAS 2 INCHES OR LESS OF WATER IN THE SNOWPACK. THIS
INCREASES TO 2 TO 4 INCHES AS ONE HEADS INTO THE CENTRAL HIGHLANDS
AND CENTRAL AND SOUTHERN AROOSTOOK COUNTY. THE NORTH WOODS LIKELY
HAVE 3 TO 5 INCHES OF WATER IN THE SNOW, WITH PERHAPS A FEW SPOTS
UP TO 6 INCHES.

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

GIVEN THE WARMTH, SNOWMELT, AND RAIN THAT MUCH OF THE REGION HAS
EXPERIENCED OVER THE PAST SEVERAL WEEKS, IT MAKES SENSE THAT SOIL
MOISTURE CONDITIONS REMAIN WETTER THAN NORMAL. THE LATEST PALMER
DROUGHT SEVERITY INDEX, WHICH MEASURES MOISTURE STATES OVER THE
LONG TERM OF WEEKS TO MONTHS, INDICATES CENTRAL AND DOWNEAST MAINE
STILL HAVE UNUSUALLY MOIST CONDITIONS. THE NEAR SURFACE MOISTURE
STATES ALSO REMAIN ON THE WET SIDE. GROUNDWATER LEVELS ARE ALSO
ABOVE NORMAL ACROSS MUCH OF OUR AREA.

...RIVER AND ICE CONDITIONS...

RIVER FLOWS CONTINUE TO STAY HIGH DUE TO RUNOFF FROM SNOWMELT AND
RAIN. MANY WATERWAYS ARE CONTINUING TO RISE OR ARE HOLDING STEADY
AT THIS HOUR FROM YESTERDAY`S PRECIPITATION AND CONTINUING
SNOWMELT. RISES SHOULD CONTINUE THROUGH THIS EVENING, BUT RIVERS
SHOULD CREST OVERNIGHT AS TEMPERATURES DROP BELOW FREEZING AND
RUNOFF HALTS. WITH TEMPERATURES TO RETURN CLOSER TO NORMAL, IT IS
EXPECTED THAT FLOWS WILL GRADUALLY DROP OVER THE NEXT SEVERAL
DAYS.

BOTH RIVER ICE COVERAGE AND THICKNESS ARE BELOW NORMAL FOR EARLY
FEBRUARY. MANY OPEN STRETCHES STILL EXIST AND WHAT ICE COVER THERE
IS IS LIKELY WEAK AND MOSTLY PACKED SLUSH OR ICE CHUNKS. IT IS
ESTIMATED THAT AVERAGE ICE THICKNESSES ARE 12 INCHES OR LESS ON
MANY RIVERS, EVEN ACROSS THE FAR NORTH. HOWEVER, ICE THICKNESS CAN
BE HIGHLY VARIABLE AND ARE PROBABLY MORE VARIABLE THIS SEASON THAN
NORMAL DUE TO HIGH FLOWS AND WARM TEMPERATURES. ALTHOUGH AVERAGE
ICE COVER IS THINNER THAN NORMAL, SOME LOCATIONS LIKELY HAVE
THICKER ICE. IN FACT, THE COAST GUARD OBSERVED A 4-FOOT-THICK
CHUNK OF FROZEN FRAZIL ICE WHILE CONDUCTING ICE-BREAKING
OPERATIONS ON THE PENOBSCOT RIVER IN BANGOR FEBRUARY 2.

SEVERAL ICE JAMS ALSO REMAIN IN PLACE ACROSS OUR REGION. IN
NORTHERN MAINE, A 2-MILE LONG ICE JAM WAS SEEN ON THE SAINT JOHN
BETWEEN ALLAGASH AND SAINT FRANCIS, WITH A MUCH SMALLER JAM IN
FRENCHVILLE. A VERY SMALL JAM WAS ALSO IN PLACE ON THE ALLAGASH
RIVER IN ALLAGASH. ON THE AROOSTOOK, ICE WAS JAMMED UP A FEW MILES
UPSTREAM FROM WASHBURN, WITH EVIDENCE OF MORE JAMMED ICE RIGHT AT
THE USGS GAGE IN WASHBURN. THERE WAS ALSO A SMALL JAM ON THE
AROOSTOOK IN MASARDIS. THESE JAMS ARE LOCKED WELL IN PLACE AND ARE
NOT ANTICIPATED TO CAUSE ANY FLOODING IN THE NEAR TERM. HOWEVER,
THESE LOCATIONS WILL NEED TO BE WATCHED CLOSELY AS WE HEAD INTO
EARLY SPRING AND APPROACH BREAKUP.

IN CENTRAL MAINE, THERE WAS EVIDENCE OF FREEZE-UP JAMS ON THE
PENOBSCOT RIVER ABOVE LINCOLN AND ON THE PISCATAQUIS RIVER IN
MAXFIELD. HOWEVER, HIGHER FLOWS DUE TO SNOWMELT AND RAIN HAD EATEN
THROUGH SOME OF THE ICE AND WATER WAS EASILY FLOWING THROUGH THE
MIDDLE OF THESE JAMS. HOWEVER, THE REMNANT ICE PIECES ALONG THE
SIDES OF THE RIVERS COULD CAUSE ISSUES LATER THIS SEASON, EITHER
BY SERVING AS A CHOKE POINT FOR MORE ICE FROM UPSTREAM OR, SHOULD
THE ICE FLUSH OUT, BY PROVIDING ADDITIONAL ICE TO JAM UP
SOMEWHERE DOWNRIVER.

ALTHOUGH RIVER ICE IS THIN AND WEAK ACROSS OUR ENTIRE AREA AT
THIS TIME, IS IS EXPECTED TO GROW AND STRENGTHEN AS WE RETURN TO
COLDER CONDITIONS. ISOLATED FREEZE-UP JAMS ARE POSSIBLE IN ANY
OPEN STRETCHES THAT REMAIN.

...IN CONCLUSION...

BASED ON THE AFOREMENTIONED INFORMATION, THE WINTER/SPRING FLOOD
POTENTIAL FOR OPEN WATER FLOODING IS BELOW NORMAL ACROSS ALL OF
NORTHERN, CENTRAL AND DOWNEAST MAINE. ALTHOUGH RIVER FLOWS ARE
STILL ABOVE NORMAL, THEY ARE EXPECTED TO SLOWLY RECEDE AS COLDER
CONDITIONS RETURN TO THE REGION. IN SPITE OF ABNORMALLY-HIGH
ANTECEDENT SOIL MOISTURE STATES, THE LACK OF A TRULY DEEP SNOWPACK
PRECLUDES A FLOOD THREAT. ALTHOUGH AN ACTIVE WEATHER PATTERN WILL
ADD TO THE SNOWPACK, IT WOULD TAKE A COMBINATION OF A HEAVY
RAINFALL EVENT AND LARGE AMOUNTS OF SNOWMELT TO CAUSE SIGNIFICANT
OPEN WATER FLOODING. AT THIS TIME, NO LARGE-SCALE RAINFALL OR
SNOWMELT EVENTS ARE ANTICIPATED OVER THE NEXT WEEK OR TWO SINCE
WE`RE RETURNING TO COLDER TEMPERATURES.

THE POTENTIAL FOR FLOODING DUE TO ICE JAMS IS NEAR NORMAL ACROSS
NORTHERN AND CENTRAL MAINE. EVEN THOUGH CURRENT ICE COVER IS
RELATIVELY THIN AND WEAK, IT IS STRONGEST AND MOST EXTENSIVE IN
NORTHERN MAINE AND BACK UP THROUGH THE CENTRAL HIGHLANDS. THE
EXPECTED TURN TOWARD COLDER CONDITIONS WILL ONLY ALLOW THE RIVER
ICE TO STRENGTHEN AND GROW. ALSO, WITH SEVERAL ICE JAMS ALREADY
WELL LOCKED INTO PLACE, A NEAR NORMAL THREAT FOR ICE-JAM RELATED
FLOODING SEEMS REASONABLE.

IN THE LOWER PENOBSCOT RIVER VALLEY AND DOWNEAST MAINE, THE ICE
JAM FLOOD THREAT IS BELOW NORMAL. ICE ON THESE RIVERS IS THIN,
WITH OPEN STRETCHES COMMON. AT THIS TIME, WE DO NOT BELIEVE THAT
THE ICE HAS ENOUGH STRUCTURAL INTEGRITY TO HOLD BACK SIGNIFICANT
AMOUNTS OF WATER. RATHER, ANY JAMS THAT FORM WILL QUICKLY BUCKLE
AND MOVE DOWNSTREAM. THIS JUSTIFIES A BELOW NORMAL THREAT FOR ICE
JAM FLOODING IN THESE AREAS. HOWEVER, SINCE THE ICE WILL HAVE A
CHANCE TO STRENGTHEN, PERSONS WITH INTERESTS ALONG AREA WATERWAYS
SHOULD CLOSELY MONITOR RIVER CONDITIONS AND THE WEATHER FORECASTS
AS WE HEAD TOWARDS EARLY SPRING.

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.

THE NEXT WINTER/SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED BY
NWS CARIBOU ON THURSDAY FEBRUARY 18, 2016.

$$

HASTINGS



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