Winter/Spring Potential Flood Outlook for Northern and Eastern Maine - 03/07/2019

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MEC003-009-019-021-029-100000-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
656 PM EST THU MAR 7 2019

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

THIS IS THE FIFTH WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR 2019,
ISSUED BY THE NATIONAL WEATHER SERVICE IN CARIBOU, MAINE. THIS
OUTLOOK IS FOR NORTHERN, CENTRAL, AND DOWNEAST MAINE FOR THE
TWO-WEEK PERIOD OF MARCH 7TH TO MARCH 21ST, 2019.

THE FLOOD POTENTIAL FOR OPEN WATER AND ICE JAM FLOODING IS WELL
ABOVE NORMAL FOR THE ENTIRE REGION, WITH THE HIGHEST THREAT BEING
ACROSS THE ST. JOHN AND AROOSTOOK RIVER BASINS WHERE A SERIES OF
ICE JAMS ARE LOCKED IN PLACE AT THIS TIME.

...CLIMATOLOGICAL GUIDANCE...

DURING THE LAST TWO WEEKS, A SERIES OF WEATHER SYSTEMS AFFECTED
THE REGION AS THEY MOVED ACROSS THE MAINE COAST AND THEN INTO THE
CANADIAN MARITIMES. THESE SYSTEMS BROUGHT SIGNIFICANT SNOWFALL TO
THE REGION WHICH ADDED TO THE EXISTING SNOWPACK ESPECIALLY ACROSS
NORTHERN AND CENTRAL AREAS. ONE SIGNIFICANT EVENT CAME IN ON
FEBRUARY 24TH AND LASTED INTO THE 25TH, WITH A FOOT OR MORE OF
SNOW ACROSS NORTHERN MAINE AND PORTIONS OF THE MAINE CENTRAL
HIGHLANDS. THE BANGOR AND DOWNEAST REGION RECEIVED AN INCH OR LESS
OF SNOW WITH A CHANGEOVER TO RAIN. THIS EVENT ALSO BROUGHT VERY
STRONG WINDS TO THE REGION WHICH LED TO NUMEROUS ROAD CLOSURES
ACROSS NORTHERN MAINE ON THE 24TH INTO THE 25TH. ANOTHER SYSTEM
AFFECTED THE REGION WITH ANOTHER ROUND OF SNOW ON MARCH 4TH. THIS
EVENT BROUGHT 10-15 INCHES OF SNOW TO THE DOWNEAST REGION WHILE
AREAS FROM BANGOR NORTHWARD RECEIVED 3 TO 8 INCHES OF SNOW.

OVER THE LAST TWO WEEKS, AFTER A BRIEF MODERATION IN TEMPERATURES,
AVERAGE TEMPERATURES DROPPED TO BELOW NORMAL DURING THE LAST WEEK
OF FEBRUARY INTO THE FIRST WEEK OF MARCH. THE OFFICIAL NATIONAL
WEATHER SERVICE 8 TO 14 DAY OUTLOOK IS CALLING FOR ABOVE NORMAL
TEMPERATURES WITH PRECIPITATION EXPECTED TO BE SLIGHTLY ABOVE
NORMAL.

THE WEATHER PATTERN OVER THE NEXT 7 TO 14 DAYS LOOKS TO BE
SOMEWHAT ACTIVE. A STORM SYSTEM COULD BRING A SIGNIFICANT SNOWFALL
TO THE REGION ON THE 10TH AND 11TH WITH THE POTENTIAL FOR AT
LEAST 3 TO 6 INCHES OF SNOW ACROSS NORTHERN MAINE INCLUDING THE
MAINE CENTRAL HIGHLANDS. THE BANGOR REGION INCLUDING THE DOWNEAST
REGION COULD SEE A FEW INCHES OF SNOW BEFORE A CHANGEOVER TO RAIN
AS WARMER MOVES IN. THIS COULD REDUCE THE SNOWPACK ACROSS THESE
AREAS. COLDER AIR IS EXPECTED TO MOVE BEHIND THIS SYSTEM AND
SETTLE INTO THROUGH THE 14TH. ANOTHER SYSTEM COULD AFFECT THE
REGION BY THE END OF THE WEEKEND OF THE 15TH AND 16TH. THIS SYSTEM
COULD BE ACCOMPANIED BY SOME RAIN AS MILDER TEMPERATURES ARE
POSSIBLE. THERE DOES APPEAR TO BE A WARMUP DURING THIS TIME
PERIOD, BUT CONFIDENCE IS LOW ON THE DEVELOPMENT AND TRACK OF THIS
SYSTEM.

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

SNOW DEPTHS RANGED FROM 38 TO 48 INCHES ACROSS NORTHERN AND
NORTHWEST MAINE WITH A FEW SPOTS HITTING ABOVE 55 INCHES. THE
TOWN OF WINTERVILLE, WHICH IS IN CENTRAL AROOSTOOK COUNTY,
CAME IN WITH 49 INCHES OF SNOW ON THE GROUND. THE NWS OFFICE IN
CARIBOU WAS RECORDED 45 INCHES OF SNOW ON THE GROUND AS OF 7 AM
THIS MORNING. SNOW DEPTHS ACROSS THE MAINE CENTRAL HIGHLANDS
RANGED FROM 35 TO 45 INCHES. MILLINOCKET LAKE RECORDED 43 INCHES
OF SNOW ON THE GROUND. THE BANGOR REGION INCLUDING THE INTERIOR
DOWNEAST RECORDED 12 TO 24 INCHES OF SNOW DEPTH. AN OBSERVER IN
THE TOWN OF ROBBINSTON, WHICH IS IN CENTRAL WASHINGTON COUNTY,
RECORDED 28 INCHES OF SNOW DEPTH. THE COASTAL REGION CAME IN WITH
8 TO 16 INCHES OF SNOW DEPTH. SNOW DEPTHS WERE NOW ABOVE NORMAL
FOR THE ENTIRE REGION.

THE SNOW WATER EQUIVALENT, OR THE AMOUNT OF WATER CONTAINED IN
THE SNOWPACK CONTINUES TO REMAIN THE HIGHEST ACROSS NORTHERN AND
CENTRAL AREAS AND HAS INCREASED OVER THE LAST TWO WEEKS. NORTHERN
MAINE INCLUDING THE MAINE CENTRAL HIGHLANDS HAVE SNOW WATER
EQUIVALENTS OF 9 TO 13 INCHES. A FEW SITES ACROSS NORTHERN AND
CENTRAL AROOSTOOK COUNTY WERE SEEING CLOSE TO 14 INCHES OF SNOW
WATER EQUIVALENT. THE NWS OFFICE IN CARIBOU SAW THE SNOW WATER
EQUIVALENT INCREASE TO 12 INCHES. WINTERVILLE CAME IN 13.5 INCHES
OF SNOW WATER EQUIVALENT. ACROSS THE BANGOR AND INTERIOR DOWNEAST
REGION, 3 TO 8 INCHES OF WATER WAS MEASURED IN THE SNOWPACK. THE
COASTAL REGIONS RECORDED 2 TO 5 INCHES OF WATER EQUIVALENT IN THE
SNOWPACK.

THE SNOW WATER EQUIVALENT IS WELL ABOVE NORMAL FOR NORTHERN MAINE
AND THE MAINE CENTRAL HIGHLANDS, WHILE FROM BANGOR TO THE
DOWNEAST COAST, SNOW WATER EQUIVALENTS WERE NEAR TO SLIGHTLY
ABOVE NORMAL.

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

SOIL MOISTURE REMAINED ABOVE NORMAL ACROSS THE ENTIRE REGION. THE
LATEST PALMER DROUGHT SEVERITY INDEX, WHICH MEASURES SOIL MOISTURE
IN THE LONGER TERM, WAS SHOWING ABOVE NORMAL CONDITIONS.

LOOKING AT THE GROUNDWATER LEVELS, COURTESY OF THE USGS, WE 
CONTINUE TO SEE THE LEVELS SLIGHTLY ABOVE NORMAL. SOME SITES
ACROSS THE DOWNEAST REGION SUCH AS ACADIA REPORTED ABOVE NORMAL
LEVELS.

...RIVER AND ICE CONDITIONS...

RIVER FLOWS REMAINED NEAR TO SLIGHTLY ABOVE NORMAL FOR THIS TIME
OF YEAR THROUGHOUT THE REGION.

ICE COVERAGE ON THE RIVERS ACROSS THE REGION WAS CLOSE TO 100% AS
OF THIS MORNING, WITH SOME OPEN SECTIONS ON THE RIVERS WHERE THE
FLOW IS STRONG. THESE OPEN SECTIONS INCLUDED THE PENOBSCOT RIVER
NEAR EDDINGTON AND THE FISH RIVER SOUTHWEST OF FORT KENT.

ICE THICKNESS ON THE PENOBSCOT RIVER VARIED FROM 12 TO 18 INCHES
AROUND THE BANGOR REGION. ON THE NORTHERN BRANCH OF THE PENOBSCOT
RIVER AT GRINDSTONE, THE ICE THICKNESS WAS MEASURED TO BE AT 25
INCHES. ICE THICKNESS ON THE KENDUSKEAG STREAM IN BANGOR REMAINED
AT 18 INCHES. THE PISCATAQUIS RIVER HAD ICE THICKNESSES OF 10 TO
16 INCHES, WITH THE THICKEST ICE NEAR DOVER-FOXCROFT. ICE
THICKNESSES ACROSS THE NORTHERN MAINE RIVERS REMAINED THE SAME
WITH AT LEAST OF FOOT OF SNOW ON THE ICE. ICE THICKNESS ON THE
ALLAGASH RIVER IN NORTHWEST MAINE STAYED AT 18 INCHES. ICE
THICKNESSES ON THE ST. JOHN RIVER FROM FORT KENT TO DICKEY WERE 8
TO 14 INCHES, WHILE EAST OF FORT KENT DOWN TO MADAWASKA AND GRAND
ISLE, ICE THICKNESSES REMAINED ESTIMATED AT 12 INCHES. THE ICE
THICKNESS ON THE AROOSTOOK RIVER WAS 24 INCHES, OR 2 FEET THICK.

ICE JAMS REMAIN LOCKED IN PLACE ON THE NORTHERN MAINE RIVERS. THE
ICE JAM ON THE AROOSTOOK RIVER FROM WASHBURN TO CROUSEVILLE HAS
STAYED LOCKED IN PLACE. ANOTHER ICE JAM REMAINED IN PLACE ON THE
AROOSTOOK RIVER NEAR THE CARIBOU-FORT FAIRFIELD TOWN LINE. ICE
JAMS REMAINED LOCKED IN PLACE ON THE ST. JOHN RIVER WITH A
SIGNIFICANT ICE JAM FROM ST. JOHN TO ST. FRANCIS. OTHER NOTABLE
ICE JAMS REMAIN ON THE ST. JOHN RIVER, FROM SOUTHEAST OF FORT
KENT DOWNSTREAM TO THE TOWN OF GRAND ISLE. THE PISCATAQUIS RIVER
HAS AN ICE JAM NEAR THE TOWN OF DOVER-FOXCROFT. ANOTHER ICE JAM
IS IN PLACE ON THE PLEASANT RIVER IN MILO. BOTH OF THESE JAMS WERE
APPROXIMATELY ONE HALF MILE LONG.

ICE COVERAGE AND ICE THICKNESS IS CONSIDERED TO BE NEAR NORMAL FOR
THIS TIME OF YEAR GIVEN THE SIGNIFICANT WARMUP AND RAIN EVENT
THAT OCCURRED BACK IN DECEMBER 2018. THAT EVENT ALLOWED THE ICE TO
BREAKUP AND MOVE. GIVEN THE VERY COLD NIGHTS THAT WERE EXPERIENCED
OVER THE LAST FEW NIGHTS WITH SEVERAL SITES SEEING TEMPERATURES
AT OR BELOW -20F, SOME INCREASE IN THE ICE THICKNESSES AND
COVERAGE IS POSSIBLE.

...IN CONCLUSION...

BASED ON THE ABOVE INFORMATION, THE FLOOD POTENTIAL FOR OPEN WATER
FLOODING IS WELL ABOVE NORMAL ACROSS THE REGION. THE THREAT FOR
ICE JAM FLOODING IS ALSO WELL ABOVE NORMAL.

IT IS IMPORTANT TO REMEMBER THAT A HEAVY RAINFALL EVENT ALONG
WITH MILD TEMPERATURES CAN LEAD TO AN INCREASED POTENTIAL FOR
FLOODING WITH SNOWMELT AND RUNOFF. ICE BREAKING UP AND JAMMING CAN
ELEVATE THE THREAT FOR FLOODING IN A SHORT PERIOD OF TIME.

THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED ON THURSDAY,
MARCH 21ST.

$$

HEWITT