Flood Potential Outlook
Issued by NWS Boston, MA

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000 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. $$ FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/BOSTON YOU CAN FOLLOW US ON FACEBOOK AT WWW.FACEBOOK.COM/NWSBOSTON YOU CAN FOLLOW US ON TWITTER AT @NWSBOSTON

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