Flood Potential Outlook
Issued by NWS Boston, MA

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FGUS71 KBOX 191958
ESFBOX
CTC003-013-015-MAC001-005-007-009-011-013-015-017-019-021-023-025-
027-NHC005-011-RIC001-003-005-007-009-212000-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE TAUNTON MA
258 PM EST THU FEB 19 2015

...THE WINTER/SPRING FLOOD POTENTIAL IS ABOVE NORMAL ACROSS SOUTHERN
NEW ENGLAND....

THE LATE WINTER/SPRING FLOOD POTENTIAL FOR RIVER AND STREAM FLOODING
IN SOUTHERN NEW ENGLAND IS ABOVE NORMAL. THE POTENTIAL FOR FLOODING
DUE TO ICE JAMS RANGES FROM NORMAL TO ABOVE NORMAL. THE POTENTIAL
FOR URBAN AND POOR DRAINAGE FLOODING IS ABOVE NORMAL.

THIS IS THE FOURTH WINTER/SPRING FLOOD POTENTIAL OUTLOOK OF THE 2015
SEASON.  FLOOD OUTLOOKS WILL BE ISSUED EVERY TWO WEEKS INTO EARLY
SPRING TO ASSESS THE POTENTIAL FOR FLOODING.  THE OUTLOOKS ARE BASED
ON CURRENT AND FORECAST HYDROMETEOROLOGICAL CONDITIONS.  THIS
INCLUDES SNOW COVER AND SNOW WATER EQUIVALENT...STREAM AND RIVER
LEVELS AND THE AMOUNT OF ICE COVERAGE...ALONG WITH EXPECTED
TEMPERATURES AND PRECIPITATION OVER THE NEXT TWO WEEKS.

...RECENT PRECIPITATION AND TEMPERATURES...

THE PAST FEW WEEKS HAVE BROUGHT AN EXCEPTIONAL AMOUNT OF SNOW TO
SOUTHERN NEW ENGLAND. MAJOR CLIMATE SITES MOST AFFECTED BY THE SNOWS
INCLUDED WORCESTER AND BOSTON.

WORCESTER/S SEASONAL SNOWFALL TOTAL AS OF FEBRUARY 18 WAS 103.8
INCHES...MOST OF THIS HAD FALLEN WITHIN THE PAST 30 DAYS.  THE
BOSTON SEASONAL SNOWFALL TOTAL AS OF FEBRUARY 18 WAS 96.3
INCHES...MOST OF THIS HAD ALSO FALLEN WITHIN THE PAST 30 DAYS.

SEASONAL SNOWFALL TOTALS WERE LESS AT PROVIDENCE AND HARTFORD...BUT
STILL RUNNING WELL ABOVE THE SNOWFALL TOTALS WE WOULD TYPICALLY
EXPECT THRU MID FEBRUARY. AT PROVIDENCE...THE SEASONAL SNOWFALL WAS
UP TO 55.1 INCHES. AT HARTFORD...SEASONAL SNOWFALL WAS UP TO 46.8
INCHES.

LIQUID EQUIVALENT PRECIPITATION FOR THE PAST 30 DAYS ACROSS CENTRAL
AND EASTERN MASSACHUSETTS...AS WELL AS NORTHERN RHODE ISLAND AND
NORTHEAST CONNECTICUT...RANGED FROM 4 TO 6 INCHES. THIS WAS ABOVE TO
WELL ABOVE NORMAL. IN THE BOSTON METRO AREA GENERALLY AROUND AND
EAST OF THE INTERSTATE 495 CORRIDOR...THE LIQUID EQUIVALENT FROM JAN
20 TO FEB 18 WAS 2 TO 3 INCHES ABOVE NORMAL.

LIQUID EQUIVALENT PRECIPITATION FOR THE PAST 30 DAYS ACROSS WESTERN
MASSACHUSETTS...NORTHERN CONNECTICUT AND SOUTHERN RHODE ISLAND
RANGED FROM 2 TO 4 INCHES.  THESE TOTALS RANGED FROM NEAR NORMAL TO
MORE THAN AN INCH BELOW NORMAL.

THE PAST FEW WEEKS WILL BE REMEMBERED FOR THE COLD AS WELL AS THE
SNOW. JANUARY AVERAGED A FEW DEGREES BELOW NORMAL FOR THE
MONTH...BUT TEMPERATURES FROM FEBRUARY 1 THROUGH FEBRUARY 18
AVERAGED 12 TO 14 DEGREES BELOW NORMAL AT MAJOR CLIMATE SITES IN THE
AREA.

...OBSERVED SNOW DEPTHS AND WATER EQUIVALENTS...

GIVEN THE UNUSUAL AND EXTENSIVE SNOWFALL THAT OCCURRED OVER THE PAST
30 DAYS...SNOW DEPTH WENT FROM NEAR ZERO IN LATE JANUARY FOR MUCH OF
THE AREA...TO AN ABOVE NORMAL TO WELL ABOVE NORMAL SNOW PACK.

THE SNOWPACK ACROSS CENTRAL AND WESTERN MASSACHUSETTS...AS WELL AS
NORTHERN CONNECTICUT...WAS GENERALLY ABOVE NORMAL FOR THIS TIME OF
YEAR. IN THESE AREAS...SNOW DEPTHS RANGED FROM 15 TO 30 INCHES...
WITH LOCALIZED HIGHER DEPTHS. SNOW WATER EQUIVALENT RANGED FROM 3 TO
7 INCHES...EXCEPT 1.5 TO 4 INCHES IN NORTHERN CONNECTICUT. THESE
EQUIVALENTS WERE GENERALLY ABOVE NORMAL.

THE SNOW DEPTH AND SNOW WATER EQUIVALENT ACROSS MOST OF EASTERN
MASSACHUSETTS AND NORTHERN RHODE ISLAND WAS WELL ABOVE NORMAL FOR
THIS TIME OF YEAR. SNOW DEPTH RANGED FROM 20 TO 40 INCHES ACROSS
MUCH OF THIS REGION...WITH LOCALIZED HIGHER TOTALS ABOVE 40 INCHES.
SNOW WATER EQUIVALENT WAS ESTIMATED TO BE 4 TO 7 INCHES...WITH
LOCALLY HIGHER AMOUNTS.

SNOW DEPTHS ACROSS SOUTHERN RHODE ISLAND...CAPE COD AND THE ISLANDS
RANGED MAINLY FROM 1 TO 2 FEET...WITH SNOW WATER EQUIVALENT
ESTIMATED AT 2 TO 4 INCHES. THIS IS WELL ABOVE NORMAL.

...RIVER AND ICE CONDITIONS...

RIVERS AND STREAMS IN SOUTHERN NEW ENGLAND WERE GENERALLY ON A
STEADY OR SLOW DECLINE. THIS IS BECAUSE RUNOFF HAS BEEN MINIMIZED
DUE TO THE WELL BELOW NORMAL TEMPERATURES. MANY RIVERS AND STREAMS
IN SOUTHERN NEW ENGLAND ARE ICE AFFECTED.

TEMPERATURES DURING JANUARY AVERAGED A FEW DEGREES BELOW
NORMAL...AND FEBRUARY TEMPERATURES MONTH TO DATE HAVE BEEN FAR BELOW
NORMAL.  THIS HAS BROUGHT PERIODS OF RIVER ICE DEVELOPMENT.

MANY SMALL RIVERS AND STREAMS IN INTERIOR SOUTHERN NEW ENGLAND HAVE
CONSIDERABLE ICE COVERAGE...BUT CONDITIONS DO VARY FROM ONE WATERWAY
TO THE NEXT.

ON THE WEST BRANCH BROOK IN CHESTERFIELD...AN ICE JAM APPROXIMATELY
6 FEET HIGH AND 20 FEET WIDE DEVELOPED AFTER A THE JANUARY 18
COMBINATION RAIN AND FREEZING RAIN EVENT...WITH 1 TO 2 INCHES OF
RAINFALL. THE COMBINATION OF RUNOFF FROM THIS EVENT CAUSED A SURGE
IN STREAM LEVELS IN THE AREA...CONTRIBUTING TO THE BREAKUP OF ICE
WHICH COLLECTED IN AT A LOCATION ALONG THE BROOK OFF ROUTE 143. THE
JAM EXTENDED 300 TO 400 FEET IN LENGTH. OFFICIALS REPORTED THAT MOST
OF THE AREA DOWNSTREAM OF THIS ICE JAM IS A SIGNIFICANT OPEN
FLOODPLAIN...HOWEVER THERE IS A BRIDGE DOWNSTREAM OF THE ICE JAM.
NO FLOOD IMPACTS WERE OCCURRING AS OF EARLY FEBRUARY AS A RESULT OF
THIS ICE JAM.

GIVEN THE VARYING RIVER ICE CONDITIONS AND THE WELL BELOW NORMAL
TEMPERATURES CONTRIBUTING TO LINGERING ICE COVERAGE ON MANY RIVERS
AND STREAMS IN THE AREA...THE RIVER ICE JAM FLOOD THREAT IS
INCREASING TO ABOVE NORMAL FOR THIS TIME OF YEAR...WITH THE MAIN
THREAT BEING OVER INTERIOR SOUTHERN NEW ENGLAND. ANY RAIN OR
RAINFALL/SNOWMELT EVENT THAT PRODUCES A RISE OF 1 TO 3 FEET ON SMALL
RIVER AND STREAMS STREAMS COULD CAUSE BREAKUP AND MOVEMENT OF RIVER
ICE...AND BRING THE POTENTIAL FOR ISOLATED BREAK UP ICE JAMS.  THE
INCREASING SUN ANGLE AS WE GET INTO LATE WINTER SHOULD HELP TO LIMIT
FURTHER RIVER ICE DEVELOPMENT.

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

AS OF FEBRUARY 19 THE SOIL MOISTURE LEVELS ACROSS SOUTHERN NEW
ENGLAND RANGED FROM NORMAL TO ABOVE NORMAL FOR THIS TIME OF YEAR.
THE GROUND WAS FROZEN TO AN UNKNOWN DEPTH.

EXAMINING GROUND WATER MONITORING WELLS ACROSS THE REGION
COURTESY OF THE UNITED STATES GEOLOGICAL SURVEY (USGS) MOST GROUND
WATER LEVELS WERE REPORTED TO BE AT OR ABOVE NORMAL LEVELS IN
MASSACHUSETTS. IN RHODE ISLAND AND NORTHERN CONNECTICUT THERE WERE
POCKETS WHERE GROUND WATER LEVELS WERE BELOW NORMAL FOR THIS TIME OF
YEAR.

WATER SUPPLY WAS NEAR NORMAL FOR THIS TIME OF YEAR.  QUABBIN
RESERVOIR WAS AT 94.6 PERCENT CAPACITY...WACHUSETT RESERVOIR AT 89.2
PERCENT CAPACITY...AND SCITUATE RESERVOIR IN RHODE ISLAND AT 86.5
PERCENT CAPACITY.

...TEMPERATURE AND PRECIPITATION OUTLOOK...

TEMPERATURES ARE EXPECTED TO STAY BELOW NORMAL...AND MOSTLY BELOW
FREEZING...DURING THE UPCOMING 7 DAYS. TEMPERATURES MAY GET CLOSE TO
NORMAL IN SOME LOCALES ON SUNDAY...WITH THE HIGH TEMPERATURE
FORECAST TO REACH THE MID 30S TO LOW 40S.

MAINLY DRY CONDITIONS ARE EXPECTED TONIGHT AND FRIDAY. HOWEVER
DURING LATER SATURDAY AND SUNDAY A WARM FRONT IS EXPECTED TO BRING A
WINTRY MIX OF PRECIPITATION...MAINLY SNOW AND RAIN...TO SOUTHERN NEW
ENGLAND. SINCE THE TEMPERATURE OF THE SNOW PACK ACROSS OUR REGION IS
STILL BELOW FREEZING...SNOWMELT IS EXPECTED TO BE MINIMAL WITH THIS
EVENT. HOWEVER...THE ABUNDANT SNOW PACK LIKELY CONTINUES TO
COVER...OR BURY...MANY STORM DRAINS IN OUR REGION. RAIN THAT FALLS
IN ROADWAYS MAY NOT BE ABLE TO FIND A QUICK OUTLET...SO POOR
DRAINAGE FLOODING IS A THREAT.

FROM NEXT MONDAY THROUGH THURSDAY...TEMPERATURES ARE EXPECTED TO
REMAIN LARGELY BELOW FREEZING ACROSS THE REGION.  SO THE SNOW PACK
IS EXPECTED TO REMAIN IN PLACE.

THE WEEK 2 OUTLOOK FROM THE CLIMATE PREDICTION CENTER FOR FEBRUARY
26 TO MARCH 4...CALLS FOR OVERALL BELOW NORMAL TEMPERATURES AND
ABOVE NORMAL PRECIPITATION.

...SUMMARY...

BASED ON THE INFORMATION AVAILABLE AT THIS TIME...THE LATE WINTER
AND SPRING FLOOD POTENTIAL IS ABOVE NORMAL ACROSS SOUTHERN NEW
ENGLAND. THE POTENTIAL FOR FLOODING DUE TO ICE JAMS IS NORMAL TO
ABOVE NORMAL...WITH THE MAIN ICE JAM POTENTIAL BEING ACROSS INTERIOR
SOUTHERN NEW ENGLAND.

BECAUSE OF THE EXTENT OF SNOWPACK AND THE LIKELIHOOD OF SNOW CLOGGED
OR BURIED DRAINS...THE THREAT FOR URBAN AND POOR DRAINAGE FLOODING
IS ABOVE NORMAL. A LIGHT TO MODERATE RAIN WITH MODEST
SNOWMELT...SUCH AS WHAT MAY OCCUR THIS WEEKEND...MAY BE SUFFICIENT
TO CAUSE POOR DRAINAGE FLOODING IN SOME LOCATIONS. THIS IS DEPENDENT
ON THE EXTENT OF SNOW CLOGGED DRAINS FROM ONE LOCATION TO THE
NEXT.

ADDITIONAL LOADING OF THE SNOWPACK IS POSSIBLE IN SOUTHERN NEW
ENGLAND ESPECIALLY IF RAINFALL OR MIXED PRECIPITATION OCCURS ON
SUNDAY FEBRUARY 22. THE HIGHER SNOW WATER EQUIVALENTS...MOIST GROUND
CONDITIONS AND INCREASING SUN ANGLE ALSO ALLOW FOR AN INCREASED
THREAT FOR FLOODING WITH TIME ACROSS THIS REGION. THE LATER WE GET
INTO FEBRUARY AND MARCH WITH THIS SNOW PACK...THE CLOSER WE WILL
NEED TO WATCH FOR THE POSSIBILITY OF WARM WEATHER EVENTS WITH RAIN
AND SNOWMELT.

KEEP IN MIND THAT HEAVY RAIN CAN CAUSE FLOODING ANY TIME OF THE
YEAR...EVEN WITHOUT A SNOWPACK. THOSE WITH INTERESTS ALONG RIVERS
AND STREAMS SHOULD CHECK THE HAZARDOUS WEATHER OUTLOOK...WHICH
HIGHLIGHTS ANY POTENTIAL FLOOD EVENTS OVER THE NEXT 7 DAYS. GO TO
WEATHER.GOV/BOSTON AND CLICK ON THE OPTION CURRENT HAZARDS...THEN
CLICK ON LOCAL OUTLOOK.

THE NEXT WINTER/SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED ON
THURSDAY MARCH 5.

$$


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