Winter/Spring Flood Potential Outlook For Northern & Eastern Maine - 03/18/2021

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK

NATIONAL WEATHER SERVICE CARIBOU ME

1005 PM EDT THU MAR 18 2021

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

DOWNEAST MAINE...

THIS IS THE SIXTH WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR 2021,

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 18TH TO APRIL 1ST, 2021.

THE FLOOD POTENTIAL FOR OPEN WATER FLOODING REMAINS SLIGHTLY 

BELOW NORMAL ACROSS THE ENTIRE REGION. THE FLOOD POTENTIAL DUE TO 

ICE JAMS REMAINS NEAR NORMAL ACROSS THE NORTHERN AND CENTRAL MAINE

RIVERS, WHILE THE DOWNEAST REGION REMAINS BELOW NORMAL.

...CLIMATOLOGICAL GUIDANCE... 

VERY MINOR SNOWFALL ACCUMULATIONS OCCURRED MARCH 9TH, MAINLY OVER

EASTERN AREAS. SNOWFALL AMOUNTS RANGED FROM 0.3 TO 3.5 INCHES.

BELOW NORMAL PRECIPITATION INCLUDES BELOW NORMAL SNOWFALL AMOUNTS

FOR THE AREA, EXCEPT FOR SLIGHTLY BELOW NORMAL SNOWFALL FOR THE 

CARIBOU AREA. 

NEAR NORMAL TEMPERATURES OCCURRED ACROSS MOST OF THE AREA ALTHOUGH

CARIBOU EXPERIENCED 1.7 DEGREES BELOW NORMAL FOR THE FIRST HALF 

OF THE MONTH.

AN ACTIVE SPLIT JET STREAM PATTERN IS FORECAST TO CONTINUE THE

REMAINDER OF MARCH. THIS OFFERS SOME CHALLENGES TO THE FORECAST

DUE TO TIMING AND PHASING OF LOW PRESSURE SYSTEMS WITH RESPECT TO

QUANTITATIVE PRECIPITATION FORECAST. SOME SIGNIFICANT TEMPERATURE

FLUCTUATION LIKELY TO OCCUR OVER THE NEXT TWO WEEKS, TYPICAL FOR 

THIS TIME OF YEAR. 

THE OFFICIAL NATIONAL WEATHER SERVICE 6 TO 14 DAY OUTLOOK IS CALLING

FOR ABOVE NORMAL TEMPERATURES AND NEAR TO SLIGHTLY ABOVE NORMAL 

PRECIPITATION.

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

SNOW DEPTHS ACROSS NORTHERN AREAS RANGED FROM 16 TO 25 INCHES. 

SOUTHEAST AROOSTOOK COUNTY IS SEEING BETWEEN 12 TO 16 INCHES, 

WHILE THE MAINE CENTRAL HIGHLANDS RANGED FROM 8 TO 12 INCHES. 

INTERIOR DOWNEAST AND THE PENOBSCOT VALLEY AVERAGED BETWEEN 1 TO 6

INCHES, WITH THE COAST SEEING TRACE AMOUNTS TO NO SNOW. SNOW 

DEPTHS ARE NORMAL ACROSS THE NORTH BUT BELOW NORMAL OVER SOUTHERN 

AREAS. 

SNOW DEPTHS HAVE DECREASED OVER THE PAST TWO WEEKS, WITH THE

HIGHEST SNOW DEPTH BEING 23.1 INCHES OF SNOW STILL REMAINING ON

THE GROUND IN WINTERVILLE. THE NWS IN CARIBOU RECORDED A DEPTH OF

16 INCHES AS OF 8 AM THIS MORNING. INTERESTINGLY ENOUGH, CHIMNEY

POND AT BAXTER STATE PARK, RECORDED A SNOW DEPTH THIS MORNING OF

AN INCREDIBLE 37 INCHES. 

SNOW DEPTHS ARE NEAR NORMAL ACROSS NORTHERN MAINE, WHILE SNOW 

DEPTHS ARE BELOW NORMAL ELSEWHERE. 

THE SNOW WATER EQUIVALENT, OR THE AMOUNT OF WATER CONTAINED IN 

THE SNOWPACK, HAS DECREASED SOME OVER THE PAST TWO WEEKS ACROSS 

NORTHERN MAINE. NORTHERN MAINE IS STILL SEEING 5 TO 7 INCHES, 

WHILE THE MAINE CENTRAL HIGHLANDS HAD 2 TO 4 INCHES. THE NWS IN 

CARIBOU RECORDED A SNOW WATER EQUIVALENT OF 5.6 INCHES. THE SNOW

WATER EQUIVALENT ESSENTIALLY REMAINED THE SAME AS TWO WEEKS AGO,

ALTHOUGH THE SNOW DEPTH HAD DECREASED FROM 25 TO 16 INCHES. THE 

HIGHEST SNOW WATER EQUIVALENT WAS REPORTED IN ALLAGASH WITH 6.8 

INCHES OF WATER IN THE SNOWPACK.

SNOW WATER EQUIVALENTS ACROSS THE PENOBSCOT VALLEY AND THE

DOWNEAST REGION RANGED FROM 1 TO 2 INCHES.

SNOW WATER EQUIVALENTS ARE NEAR NORMAL ACROSS THE NORTH WITH  

BELOW NORMAL ELSEWHERE.

THE FROST DEPTH AT NWS CARIBOU REMAINS AT 6 INCHES. 

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

THE LATEST PALMER DROUGHT SEVERITY INDEX, WHICH MEASURES SOIL 

MOISTURE IN THE LONGER TERM, SHOWS NEAR NORMAL CONDITIONS FOR ALL

AREAS.

A LOOK AT THE GROUNDWATER LEVELS, COURTESY OF THE USGS, SHOWED

MAINLY NEAR NORMAL ACROSS THE REGION. A COUPLE OF EXCEPTIONS WERE

CLAYTON LAKE IN NORTHWEST AROOSTOOK COUNTY AND AMHERST IN HANCOCK

COUNTY, REPORTING BELOW NORMAL GROUNDWATER LEVELS. THERE STILL 

EXISTS ENOUGH OF A SNOWPACK NORTH AND WEST OF THE DOWNEAST REGION

THAT IS AVAILABLE FOR RECHARGE. 

...RIVER AND ICE CONDITIONS...

RIVER FLOWS WERE NEAR NORMAL ACROSS MUCH OF THE REGION, WITH THE 

EXCEPTION OF THE ST. CROIX RIVER BASIN, AS FLOWS REMAIN SLIGHTLY 

BELOW NORMAL.

ABOUT 90% OF THE STREAMS AND RIVERS ACROSS THE REGION ARE SNOW 

AND ICE COVERED, INCLUDING THE PENOBSCOT AND PISCATAQUIS RIVERS.

THERE ARE OPEN AREAS OF WATER ON THE NORTHERN AND CENTRAL MAINE 

RIVERS, INCLUDING THE PENOBSCOT, PISCATAQUIS, AROOSTOOK AND ST. 

JOHN RIVER. ACROSS THE DOWNEAST REGION, THE MILDER TEMPERATURES 

HAVE ALLOWED THE ICE TO WEAKEN AND FLUSH OUT. THIS CAN BE SEEN 

ALONG THE ST. CROIX RIVER, WHERE MANY OPEN AREAS OF WATER WERE 

OBSERVED DURING THE PAST WEEK. 

ICE THICKNESSES RANGED FROM 14 TO 20 INCHES ACROSS THE AROOSTOOK 

AND ST. JOHN RIVER BASINS, INCLUDING THE ALLAGASH RIVER. THE 

THICKEST ICE WAS ACROSS THE ST. JOHN RIVER WEST OF FORT KENT AND 

ON THE ALLAGASH RIVER. THE FISH RIVER HAS OPENED UP CONSIDERABLY 

ESPECIALLY IN THE FORT KENT REGION OVER THE LAST TWO WEEKS. THERE 

IS STILL A GOOD STRETCH OF THE RIVER, SOUTH OF THE FORT KENT 

REGION, THAT STILL HAD SOME SNOW AND ICE COVER. 

THE PENOBSCOT RIVER REMAINED ICE COVERED NORTH OF THE HOWLAND 

REGION INTO MILLINOCKET. LARGE OPEN SECTIONS SOUTH OF HOWLAND 

DOWN TO THE BANGOR REGION. ICE WAS SHOWING SIGNS OF THINNING OVER 

THE PAST WEEK. THE EAST BRANCH OF THE PENOBSCOT RIVER AT 

GRINDSTONE WAS ICE COVERED WITH A COUPLE OF OPEN STRETCHES TO THE 

SOUTH. ICE THICKNESS WAS MEASURED BY THE USGS TO BE AROUND 18 

INCHES AT GRINDSTONE. THE KENDUSKEAG STREAM IN DOWNTOWN BANGOR, 

WERE THE KENDUSKEAG STREAM MEETS UP WITH THE PENOBSCOT RIVER, WAS 

STILL ICE COVERED WITH ICE THICKNESS OF 15 TO 18 INCHES. 

THE MATTAWAMKEAG RIVER WAS 90% ICE COVERED WITH SOME OPEN 

SECTIONS OF WATER HEADING TOWARD THE CONFLUENCE OF THE 

MATTAWAMKEAG AND PENOBSCOT RIVER. ICE THICKNESS WAS MEASURED BY 

THE USGS TO BE 18 INCHES. THE PISCATAQUIS RIVER FROM BLANCHARD TO 

DOVER-FOXCROFT WAS ICE COVERED WITH SOME OPEN SECTIONS ALONG THE 

SIDES, WHILE ICE REMAINED ON THE PISCATQUIS RIVER TOWARD THE 

MAXFIELD AND MEDFORD REGION. ACCORDING TO THE USGS, ICE 

THICKNESSES WERE UP TO 18 INCHES IN SOME LOCATIONS.

THERE ARE SOME ICE JAMS REMAINING IN PLACE. ONE BUNCHED UP JAM 

RESIDES ON THE AROOSTOOK RIVER JUST EAST OF THE CARIBOU-FORT

FAIRFIELD TO THE FORT FAIRFIELD BRIDGE. THIS JAM IS APPROXIMATELY

7 MILES IN LENGTH. THE JAM REMAINS BROKEN UP IN SPOTS ALONG THIS 

STRETCH. AN ICE JAM REMAINS IN PLACE ON THE ALLAGASH RIVER NEAR 

THE BRIDGE WHERE THE ALLAGASH RIVER MEETS THE ST. JOHN RIVER. THIS

BUNCHED UP JAMS EXTENDS BACK TO THE WEST FOR ABOUT 2 MILES. THERE

IS SOME LARGE AREAS OF BUNCHED UP ICE ON THE ST. JOHN RIVER FROM 

ST. JOHN TO THE TOWN OF ALLAGASH. 

ICE COVERAGE AND THICKNESSES ARE BELOW NORMAL FOR THIS TIME OF 

YEAR. 

...IN CONCLUSION...

THE FLOOD POTENTIAL FOR OPEN WATER FLOODING IS SLIGHTLY BELOW 

NORMAL ACROSS THE ENTIRE REGION. THE FLOOD POTENTIAL DUE TO ICE 

JAMS REMAINS NEAR NORMAL FOR THE NORTHERN MAINE RIVER BASINS. THE

FLOOD POTENTIAL FOR ICE JAM FLOODING IS ALSO NEAR NORMAL ACROSS 

THE PISCATAQUIS AND PENOBSCOT RIVER RIVERS, GIVEN THE LATEST ICE 

THICKNESSES AND ICE COVERAGE. 

IT IS IMPORTANT TO REMEMBER THAT A HEAVY RAINFALL EVENT ALONG 

WITH MILD TEMPERATURES, OR A PROLONGED WARMUP IN 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, 

APRIL 1ST.

$$

HEWITT