Flood Potential Outlook
Issued by NWS Caribou, ME

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
1218 PM EDT THU MAR 12 2015

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

THIS IS THE SIXTH WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR
2015...ISSUED BY THE NATIONAL WEATHER SERVICE IN CARIBOU, MAINE.
THIS INTERMEDIATE WINTER/SPRING FLOOD POTENTIAL OUTLOOK IS FOR
NORTHERN, CENTRAL AND DOWNEAST MAINE FOR THE ONE-WEEK PERIOD FROM
MARCH 12 THROUGH MARCH 19, 2015.

THE WINTER/SPRING FLOOD POTENTIAL FOR THE CENTRAL MAINE HIGHLANDS
SOUTH TO THE COAST IS ABOVE NORMAL. FOR NORTHERN MAINE, THE FLOOD
POTENTIAL IS NEAR NORMAL, WITH FAR NORTHERN PORTIONS OF THE
COUNTY LIKELY A BIT BELOW NORMAL FOR EARLY MARCH.

THE POTENTIAL FOR FLOODING DUE TO ICE JAMS IS SLIGHTLY ABOVE
NORMAL FOR ALL OF NORTHERN, CENTRAL, AND DOWNEAST MAINE.

...CLIMATOLOGICAL GUIDANCE...

AFTER A BRUTALLY COLD FEBRUARY, WE`VE FINALLY STARTED SEEING A BIT
OF SPRING-LIKE WEATHER. HOWEVER, THIS MILD SPELL WILL BE BRIEF AS
UPPER LEVEL TROUGHING WILL RETURN TO THE NORTHEASTERN UNITED
STATES FOR THE SECOND HALF OF THE MONTH. THIS MEANS A RETURN TO
COLDER TEMPERATURES. WE ARE EXPECTING A COUPLE OF STORM SYSTEMS TO
AFFECT EASTERN NEW ENGLAND OVER THE NEXT WEEK OR SO. ONE SYSTEM
THIS WEEKEND WILL BRING MAINLY SNOW, ESPECIALLY ACROSS DOWNEAST
AREAS, WHILE THE NORTH COULD MISS OUT AGAIN. ANOTHER SYSTEM EARLY
NEXT WEEK LOOKS TO BRING SNOW TO JUST ABOUT EVERYWHERE, WITH
LOCATIONS FROM ROUGHLY BANGOR SOUTH CHANGING OVER TO RAIN FOR A
TIME. BEYOND THAT, PRECIPITATION TRENDS ARE HARDER TO DETERMINE.

THE OFFICIAL NATIONAL WEATHER SERVICE 6 TO 14 DAY OUTLOOK FOR
MARCH 17 THROUGH 25 SUPPORTS THE ABOVE THINKING WELL, CALLING FOR
BELOW NORMAL TEMPERATURES WITH PRECIPITATION AROUND NORMAL.

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

THE MOST SIGNIFICANT TREND OVER THE PAST WEEK HAS BEEN RIPENING
OF THE SNOWPACK AS THE WARM TEMPERATURES AND STRENGTHENING SUN
HAVE ALLOWED FOR PLENTIFUL SNOWMELT. IN ADDITION, SNOW DEPTHS HAVE
DROPPED DRAMATICALLY. WHILE DOWNEAST MAINE IS STILL COVERED BY THE
DEEPEST PACK, IT HAS DROPPED TO 25 TO 30 INCHES IN MOST LOCATIONS.
FAR EASTERN WASHINGTON COUNTY IS LIKELY STILL COVERED WITH CLOSE
TO 3 FEET OF SNOW. THE SNOWPACK DECREASES TO 18 TO 26 INCHES IN
THE CENTRAL HIGHLANDS AND SOUTHERN AROOSTOOK COUNTY. NORTHERN
AROOSTOOK COUNTY HAS 10 TO 18 INCHES OF SNOW, WITH THE HIGHER
ELEVATIONS IN THE NORTH MAINE WOODS REPORTING AROUND 2 FEET.
DOWNEAST MAINE STILL HAS ABOVE NORMAL SNOWPACK, BUT IT`S GENERALLY
AROUND NORMAL OVER THE REST OF THE STATE. THE EXCEPTION IS FAR
NORTHERN AREAS WHICH ARE A BIT BELOW NORMAL.

THE SNOW WATER EQUIVALENT, OR THE AMOUNT OF WATER CONTAINED IN
THE SNOWPACK, IS STILL WELL ABOVE NORMAL OVER DOWNEAST MAINE.
EVEN WITH THE SNOW MELT THAT HAS OCCURRED RECENTLY, THERE IS STILL 6
TO 8 INCHES OF WATER CONTAINED IN THE SNOW IN THESE LOCATIONS. THE
SWE LESSENS AS ONE HEADS NORTH, WITH THE CENTRAL HIGHLANDS AND
SOUTHERN AROOSTOOK COUNTY REPORTING 5 TO 7 INCHES OF WATER IN THE
PACK WITH LOCALLY HIGHER AMOUNTS, WHICH IS A BIT ABOVE NORMAL.
MUCH OF THE REMAINDER OF THE STATE HAS 4 TO 6 INCHES OF LIQUID
EQUIVALENT. THIS IS FAIRLY CLOSE TO NORMAL. THE EXCEPTION IS
ACROSS THE FAR NORTH WHERE THERE IS 2 TO 5 INCHES OF WATER IN THE
SNOWPACK, WHICH IS BELOW NORMAL FOR EARLY TO MID MARCH.

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

IN SPITE OF THE RECENT SNOWMELT, NEAR SURFACE SOIL MOISTURE
CONDITIONS, WHICH ARE INDICATIVE OF NEAR TERM MOISTURE TRENDS,
HAVE CONTINUED TO DRY OUT ACROSS MUCH OF OUR FORECAST AREA.
ANTECEDENT MOISTURE STATES ARE NEAR NORMAL OVER MUCH OF THE
REGION, WITH COASTAL MAINE STILL RUNNING ABOVE NORMAL.

THE LATEST PALMER DROUGHT SEVERITY INDEX, WHICH TAKES A LOOK AT
MOISTURE STATES OVER THE LONGER RANGE OF WEEKS TO MONTHS, SHOWS
NEAR NORMAL MOISTURE STATES, THOUGH COASTAL AREAS ARE, AGAIN,
REPORTING UNUSUALLY MOIST TO VERY MOIST CONDITIONS DUE TO THE
NUMEROUS SNOW EVENTS THEY SAW THROUGH THE WINTER.

...RIVER AND ICE CONDITIONS...

RIVER FLOWS HAVE CONTINUED TO HOLD FAIRLY STEADY OVER THE PAST
SEVERAL DAYS, WITH A FEW OF THE CENTRAL AND SOUTHERN WATERWAYS
SHOWING MODEST RISES. THIS IS BECAUSE A GOOD PART OF THE SNOW MELT
WE`VE EXPERIENCED RECENTLY HAS BEEN ABSORBED BY THE EXISTING
SNOWPACK. RIVER FLOWS ARE GENERALLY NEAR NORMAL ACROSS THE REGION,
ESPECIALLY IN THE NORTH AS THOSE LOCATIONS TYPICALLY DON`T SEE
MUCH SNOWMELT DURING EARLY MARCH ANYWAY. DOWNEAST WATERWAYS MAY
AGAIN BE THE EXCEPTION TO THIS RULE, AS THEY`RE PROBABLY RUNNING
BELOW NORMAL THERE.

ICE THICKNESSES ARE GENERALLY 1 TO 2 FEET ACROSS OUR ENTIRE AREA,
WITH THE COASTAL WATERWAYS AVERAGING CLOSE TO A FOOT. THIS IS
FAIRLY CLOSE TO NORMAL. WHAT IS ABNORMAL IS THE STRENGTH OF THE
ICE, ESPECIALLY IN OUR CENTRAL AND MORE SOUTHERN RIVERS. ALTHOUGH
WE HAVE STARTED SEEING SOME SIGNS OF WEAKENING AND ROT, THE ICE IS
STILL VERY STRONG, EVEN ACROSS OUR MORE SOUTHERN BASINS. THIS IS
LIKELY DUE TO THE ANOMALOUSLY COLD TEMPERATURES THAT WE
EXPERIENCED THROUGH FEBRUARY AS WELL AS THE DEEP AMOUNT OF SNOW
THAT STILL COVERS THE RIVER ICE. ALTHOUGH THE STRENGTHENING SUN
WILL CONTINUE TO WORK ON THE RIVER ICE AND THE SNOW THAT LIES ATOP
IT, COLDER THAN NORMAL TEMPERATURES WILL LIKELY KEEP THE ICE
UNUSUALLY STRONG THROUGH THE REMAINDER OF THE MONTH.

WE CONTINUE TO MONITOR SEVERAL ICE JAMS THAT REMAIN LOCKED IN
PLACE ALONG MANY OF OUR RIVERS. THESE JAMS INCLUDE A 10-15 MILE
LONG JAM ON THE SAINT JOHN THROUGH SAINT FRANCIS, AS WELL AS SEVERAL
SMALLER JAMS LOCATED FURTHER DOWNSTREAM ON THE SAINT JOHN BETWEEN
FORT KENT AND VAN BUREN. THERE ARE ALSO SEVERAL KNOWN JAMS ON THE
AROOSTOOK RIVER, INCLUDING ONE IN WASHBURN THROUGH CROUSEVILLE,
ONE BETWEEN PRESQUE ISLE AND CARIBOU, AND ANOTHER DOWNSTREAM OF
FORT FAIRFIELD. FOR THE CENTRAL RIVERS, WE`VE NOTED ICE JAMS ON
THE PISCATAQUIS IN MAXFIELD, AND THE PENOBSCOT RIVER NEAR ORONO.
THESE JAMS ARE WELL FROZEN IN PLACE AND HAVE NOT MOVED NOR CAUSED
ANY FLOODING ISSUES THROUGH THE LATER WINTER MONTHS. HOWEVER, THEY
WILL BEAR WATCHING AS WE HEAD THROUGH THE SPRING AS THEY WILL
LIKELY SERVE AS A FOCUS FOR BREAK UP JAMS AND/OR WILL PROVIDE
AMPLE ICE DEBRIS AVAILABLE TO JAM DOWNSTREAM.

...IN CONCLUSION...

BASED ON THE AFOREMENTIONED INFORMATION, THE WINTER/SPRING FLOOD
POTENTIAL IS ABOVE NORMAL FOR ALL OF CENTRAL AND DOWNEAST MAINE,
INCLUDING THE PENOBSCOT, PISCATAQUIS, AND SAINT CROIX RIVER
BASINS. ALTHOUGH RIVER FLOWS ARE NEAR TO A BIT BELOW NORMAL IN
THESE AREAS, ANTECEDENT MOISTURE STATES ARE LARGELY ABOVE NORMAL,
ESPECIALLY DOWNEAST. THE SNOWPACK AND THE LIQUID WATER EQUIVALENT
CONTAINED THEREIN ARE ALSO ABOVE NORMAL. WE`VE ALREADY SEEN SOME
SLIGHT RISES IN RIVER LEVELS DUE TO THE MELTING SNOW. ALTHOUGH
TEMPERATURES WILL BE BELOW NORMAL FOR THE LATTER HALF OF THE
MONTH, ANY SUNSHINE WILL ALLOW SNOWMELT TO CONTINUE. THIS WILL
ALLOW THE SNOWPACK TO RIPEN AND START CONTRIBUTING MORE MELT TO
RUNOFF. THIS WILL LEAVE THE REGION VERY VULNERABLE TO ANY MAJOR
RAIN EVENTS RIGHT INTO APRIL. EVEN IF WE DON`T GET ANY SIGNIFICANT
RAIN EVENTS, WITH SO MUCH WATER ALREADY CONTAINED IN THE SNOW, IT
IS STILL MORE LIKELY THAN NORMAL THAT WE WILL SEE FLOODING IN
THESE AREAS THIS SPRING.

ACROSS THE REMAINDER OF THE STATE, THE WINTER/SPRING FLOOD
POTENTIAL IS NEAR NORMAL TO A BIT BELOW NORMAL OVER FAR NORTHERN
MAINE. IN THESE AREAS, THE PRIMARY IMPETUS IN THE NEAR NORMAL
DESIGNATION IS THE NEAR NORMAL SNOW DEPTHS AND AMOUNTS OF WATER
IN THAT PACK. GIVEN THIS IN ADDITION TO THE NEAR NORMAL RIVER
FLOWS, NEAR NORMAL GROUNDWATER LEVELS, AND SOMEWHAT DRY
ANTECEDENT CONDITIONS, A NEAR NORMAL FLOOD THREAT SEEMS
REASONABLE. FAR NORTHERN MAINE HAS A BIT LESS SNOW AND LIQUID
EQUIVALENT THAN WHAT WE`D NORMALLY SEE IN EARLY MARCH, SO THIS
AREA`S FLOOD POTENTIAL IS A BIT BELOW NORMAL.

THE POTENTIAL FOR FLOODING DUE TO ICE JAMS IS SLIGHTLY ABOVE
NORMAL ACROSS THE ENTIRE AREA. THE RIVER ICE IS QUITE THICK AND
ALTHOUGH IT IS NOT ABNORMALLY SO, IT IS STILL VERY STRONG AND
SOLID. THE WARMING SUN WILL HAVE A VERY HARD TIME WORKING ON THE
RIVER ICE, ESPECIALLY SINCE THE ICE IS STILL COVERED BY AS MUCH AS
30 INCHES OF SNOW IN SOME PLACES. THEREFORE, THE ICE WILL LIKELY
STAY STRONG OVER THE NEXT FEW WEEKS, MEANING THE ICE JAM THREAT
WILL ALSO REMAIN THROUGH THE REMAINDER OF THE MONTH INTO APRIL.
THEREFORE ANY LARGE SCALE RUNOFF EVENTS OVER THE NEXT 6 WEEKS OR
SO WILL HAVE THE POTENTIAL TO CAUSE ICE JAM FLOODING. THIS EASILY
JUSTIFIES AN ABOVE NORMAL THREAT.

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 MARCH 19, 2015.

$$

HASTINGS



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