Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 182352
AFDCAR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CARIBOU ME
752 PM EDT SAT APR 18 2015

.SYNOPSIS...
LOW PRESSURE WILL MOVE SOUTH OF THE REGION TONIGHT. HIGH PRESSURE
WILL BUILD IN FROM THE NORTHWEST ON SUNDAY. THE HIGH WILL MOVE
EAST MONDAY. A LARGE AREA OF LOW PRESSURE FROM THE GREAT LAKES
WILL BEGIN TO APPROACH MONDAY NIGHT...THEN SLOWLY REFORM ALONG THE
DOWNEAST COAST TUESDAY AND TUESDAY NIGHT.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
745 PM UPDATE...HYDROLOGY SECTION HAS BEEN UPDATED FOR THE LATEST
ICE JAM INFORMATION. SEE BELOW.

612 PM UPDATE...LOW PRES CROSSING THE CT RIVER VALLEY WILL MOVE
OFF THE COAST VCNTY OF CAPE COD THIS EVENING AND CONTINUE OFFSHORE
TONIGHT. AN INVERTED TROUGH WILL EXTEND FROM THE LOW BACK INTO SW
MAINE THROUGH EARLY SUNDAY MORNING. RAIN IS CURRENTLY MOVING EAST
ACROSS SOUTHERN MAINE. MOST OF THE RAIN THIS EVENING WILL BE
ACROSS THE SOUTHWEST CORNER OF THE CWA FROM AROUND GREENVILLE AND
INTO PARTS OF DOWNEAST MAINE FROM SOUTHERN PENOBSCOT COUNTY AND
INTO HANCOCK COUNTY. MAIN ADJUSTMENT WILL BE TO THE POPS/QPF THIS
EVENING BASED ON THE LATEST RADAR AND NEAR TERM MODEL TRENDS.

PREVIOUS DISCUSSION...
WE COULD BE SEEING SOME SNOW LATER TONIGHT THROUGH ABOUT 2 AM.

SATELLITE IMAGERY SHOWED INCREASING CLOUDS W/THE BEST ENHANCEMENT
OCCURRING ACROSS SOUTHERN AND SOUTHWESTERN MAINE. LIGHTNING
DETECTION SHOWED SOME ACTIVITY ACROSS EASTERN NH AND SOUTHERN ME
AS 12Z UA SHOWED SOME WEAK LLVL WAA W/COLD POOL IN THE MID LEVELS.
THIS ACTIVITY SHOULD WEAKEN AS IT MOVES ENE THIS EVENING INTO
TONIGHT. LOW PRES PASSING S OF THE STATE THIS EVENING WILL MOVE INTO
THE GULF OF MAINE W/AN INVERTED TROF FROM THE LOW BACK THROUGH
WEST-CENTRAL MAINE. STRONG LLVL CONVERGENCE ALONG W/DECENT MID
LEVEL FORCING WILL LEAD TO A PERIOD OF ENHANCED PRECIP LATER THIS
EVENING INTO THE OVERNIGHT HOURS. THE PRECIP WILL BE IN THE FORM
OF RAIN INITIALLY W/THE HIGHEST AMOUNTS ACROSS THE CENTRAL
HIGHLANDS(GREENVILLE REGION) DOWN INTO THE BANGOR AND ELLSWORTH
REGION. AS THE TROF PIVOTS ENE LATER TONIGHT, THE PRECIP SHIELD
WILL LIFT ENE ACROSS PORTIONS OF NORTHERN AND EASTERN MAINE.
DECIDED TO PUSH FOR 80% POPS ACROSS THE SW AND DOWNEAST AREAS THIS
EVENING AND STAYED W/CHANCE POPS FURTHER N. TEMPERATURES COOL OFF
TONIGHT AND W/EVAPORATIVE COOLING, PRECIP WILL HAVE THE CHANCE TO
CHANGE TO A PERIOD OF SNOW BEFORE ENDING AFTER 2 AM SUNDAY
MORNING. MODEL SOUNDINGS, ESPECIALLY THE NAM SHOWED SB CAPE OF
50-80 JOULES AND 850-700MBS LAPSE RATES AROUND 6.5 C/KM TO ALLOW
FOR A 2-3 HRS PERIOD OF ENHANCED PRECIP BEFORE WINDING DOWN.
DECIDED OF QPF AMOUNTS OF AREAL WIDE OF 0.10-0.30" W/ONCE AGAIN
HIGHEST AMOUNTS ACROSS UPSLOPE REGIONS OF WEST-CENTRAL MAINE AND
DOWNEAST. CARRIED UP TO ONE INCH OF WET SNOW MAINLY ACROSS THE
HIGHER TERRAIN PISCATAQUIS COUNTY.

HIGH PRES BUILDS ACROSS SOUTHERN MAINE ON SUNDAY AND THEN PASSES
THROUGH THE GULF OF MAINE SUNDAY NIGHT. THIS WILL LEAD TO CLEARING
CONDITIONS BUT BELOW NORMAL TEMPERATURES BOTH SUNDAY INTO SUNDAY
NIGHT.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
BOTH THE SHORT AND LONG TERM WILL BE MARKED BY THE NAO
TELECONNECTION INDEX BECOMING MUCH MORE NEGATIVE AND THE PNA INDEX
BECOMING SOMEWHAT POSITIVE. BOTH OF THESE HEMISPHERIC CENTERS OF
ACTION ACTING IN CONCERT FAVOR SHARP UPPER TROFFING AND UPPER LOWS
STAGNATING FROM THE MID ATLC STATES NWRD INTO ERN CAN...ALONG WITH
IT A PROTRACTED PD WHERE LENGTHY PDS OF RNFL ARE ONLY TEMPORARILY
BROKEN BY BRIEF DRY SPELLS BETWEEN SUCCESSIVE S/WVS ROTATING ARND
A BROAD UPPER LOW ESTABLISHED BY MID WEEK. THIS PATTERN...IS NOT
UN-TYPICAL FOR THIS PTN OF THE U.S. IN MID TO LATE SPRING...
LASTING A WEEK OR MORE WHEN IT OCCURS...SOMETIMES OCCURRING 2 TO 3
TIMES PRIOR TO SUMMER.

AT LEAST MON WILL BEGIN DRY...THEN WITH THE INITIAL HI CLDS
ARRIVING IN THE MORN...THEN CLDS SHOULD THICKEN DURG THE AFTN HRS
WITH RNFL ARRIVING LATE IN THE DAY. THERE MAY BE JUST ENOUGH COLD
AIR ALF AOA 925 MB OVR NRN PTNS OF THE FA...WHEN EVAPORATIONAL...
DYNAMIC AND NOCTURNAL COOLING ARRIVE LATER MON NGT...PRECIP COULD
MIX WITH OR EVEN CHG TO SN SPCLY ACROSS HIER TRRN WHERE THERE
COULD BE MINOR ACCUMULATIONS OF SNFL BY MON MORN. ANY MIXED PRECIP
SHOULD CHG BACK TO ALL RN OVR MOST NRN LCTNS BY LATE TUE MORN AS
SFC TO BL TEMPS RISE SEVERAL DEG F FROM ERLY MORN LOWS. RNFL THRU
TUE AFTN WILL RANGE FROM ABOUT A HALF INCH FAR N TO 1.00 TO 1.50
INCHES ALG THE DOWNEAST COAST...ALL JUSTIFYING CATEGORICAL POPS TO
NEAR 100 PERCENT SPCLY DURG THE 6 HR PDS WHEN WE XPCT THE MOST
QPF...MSLY TUE MORN AND AFTN BASED ON THE LATEST CONSENSUS OF
MODEL GUIDANCE. AFT NEAR AVG DAY TM HI TEMPS MON AND LOW TEMPS
OVRNGT...HI TEMPS TUE WILL BE DECIDELY BLO AVG...HELD DOWN BY
RNFL...CLD CVR AND A RAW ESE WIND.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MOST MODELS INDICATE A LITTLE MORE ADDITIONAL RNFL TUE EVE AS A
SECONDARY SFC LOW MOVES E FROM THE DOWNEAST COAST INTO THE CAN
MARITIMES. AFT A BRIEF BREAK IN ORGANIZED RNFL LATE TUE NGT AND
WED MORN...ANOTHER S/WV MOVING ENE FROM AN ESTABLISHED UPPER LOW
OVR THE GREAT LKS WILL BRING A ROUND OF SHWRS WITH MSLY LGT QPF
WED AFTN AND EVE AS IT CROSSES THE FA. AFT ANOTHER BRIEF BREAK IN
RNFL LATE WED NGT...A MORE PRONOUNCED S/WV MORE CLOSELY ASSOCIATED
WITH THE UPPER LOW MOVG TOWARD NEW ENG WILL LIKELY PRODUCE A MORE
SIG ROUND OF RNFL FOR THE REGION THU INTO THU EVE...WITH
INTERMITTENT SHWRS THEN CONTG LATE THU NGT THRU SAT AS THE UPPER
LOW SLOWLY MOVES INTO NRN NEW ENG. CANNOT RULE OUT RNFL BEING
MIXED WITH OR EVEN CHGNG TO WET SN AT TMS LATE THU NGT AND SPCLY
LATE FRI NGT AS COLDER AIR ALF WITH THE UPPER LOW WORKS EWRD INTO
THE FA FROM SW QB PROV. TEMPS WITH THIS REGIME WILL CONT BLO AVG
BY DAY AND NEAR TO SLGTLY BLO AVG AT NGT.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: VFR GOING TO A PERIOD OF MVFR LATER THIS EVENING INTO
EARLY SUNDAY MORNING AND THEN AN IMPROVEMENT TO VFR BY DAYBREAK
SUNDAY. VFR RIGHT ALL TERMINALS SUNDAY THROUGH SUNDAY NIGHT.

SHORT TO LONG TERM: ALL SITES INITIALLY VFR MON...THEN MVFR MON
NGT THRU THU IN LOW CLD CVR AND RNFL...WITH PDS OF IFR ATTMS IN
HEAVIER RNFL.

&&

.MARINE...
NEAR TERM: CONDITIONS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA
THROUGH THE PERIOD. WINDS AND SEAS WILL COME UP A BIT LATER
TONIGHT INTO SUNDAY W/GUST TO NEAR 20 KT AND THIS WILL MAINLY BE
ACROSS THE OUTER WATERS.

SHORT TO LONG TERM: A GALE WATCH APPEARS TO BE LIKELY FOR LATER
MON NGT INTO TUE WITH THE ESE GRAD WIND AHEAD OF BOTH THE PRIMARY
LOW OVR ERN CAN AND THE DEVELOPING SECONDARY LOW ALG THE DOWNEAST
COAST. ALSO...THERE WILL BE SOME POTENTIAL OF MINOR COASTAL
FLOODING ALONG LOW LYING PTNS OF OUR COAST WITH THE LATE MON NGT
HI TIDAL CYCLE WITH THE INCREASING WINDS AND WVS. BOTH EVENTS ARE
STILL OUT IN DAY 3...TO FAR OUT IN THE FCST FOR HDLN STATEMENTS
ATTM...BUT WE WILL MENTION THESE CONCERNS IN AN UPDATED HWO.
OTHERWISE...WINDS AND SEAS WILL GRADUALLY DIMINISH TO SCA RANGE
ON WED AND LIKELY CONT IN THE SCA RANGE THRU THU WHEN THE LAST SIG
LOW AND ASSOCIATED SE SFC PRES GRAD MOVES E INTO THE CAN
MARITIMES.

&&

.HYDROLOGY...
745 PM UPDATE...THE FLOOD WARNING FOR THE AROOSTOOK RIVER AT
WASHBURN CONTINUES THROUGH TONIGHT DUE TO ICE JAM FLOODING.
LATEST RIVER GAGE READINGS INDICATE THE RIVER HAS ACTUALLY GONE UP
OVER THE PAST HOUR, AND THIS HAS BEEN VERIFIED BY SPOTTERS THAT
REPORT GARDNER CREEK ROAD IS ONCE AGAIN COVERED WITH 1-2 FEET OF
WATER. WE ARE SEEING SIGNS OF ICE MOVEMENT AT MASARDIS, AS WELL.
THIS COULD BE PROBLEMATIC IF THE ICE FLUSHES FROM MASARDIS AND
MEETS UP WITH THE WASHBURN JAM. ELSEWHERE ON THE AROOSTOOK, THERE
IS STILL A SMALL JAM NEAR CROUSEVILLE, ANOTHER ABOUT 2 MILES
UPSTREAM OF THE CARIBOU DAM, AND ONE DOWNSTREAM OF FORT FAIRFIELD.
THE ONLY ONE OF THESE CAUSING KNOWN FLOODING ISSUES IS FORT
FAIRFIELD, WHERE RIVERSIDE AVENUE REMAINS CLOSED.

ON THE SAINT JOHN RIVER...THE ICE HAS FLUSHED OUT OF THE ALLAGASH
AND HAS BECOME JAMMED AT ITS CONFLUENCE WITH THE SAINT JOHN. WATER
HAS STARTED BACKING UP BEHIND THIS JAM BUT IS NOT YET THREATENING
ANY STRUCTURES OR ROADS. HOWEVER, A JAM REMAINS IN PLACE NEAR THE
ST FRANCIS/ALLAGASH LINE THAT IS CAUSING WATER TO BEGIN TO COVER
PORTIONS OF ROUTE 161. MUCH LIKE THE AROOSTOOK, THERE ARE CONCERNS
THAT THE ALLAGASH JAM WILL FLUSH OUT AND MEET UP WITH THE ST
FRANCIS ONE.

RIVER FLOWS SHOULD GENERALLY BEGIN TO DECLINE LATER THIS EVENING
AS TEMPERATURES DROP BELOW FREEZING AND SNOWMELT RUNOFF SLOWS AND
STOPS. HOWEVER, ADDITIONAL ICE MOVEMENT WILL STILL BE POSSIBLE FOR
AT LEAST THE NEXT SEVERAL HOURS. PLEASE STAY ALERT FOR CHANGING
RIVER CONDITIONS.

PREVIOUS DISCUSSION...WE CONTINUE TO MONITOR THE AROOSTOOK AND
SAINT JOHN RIVERS FOR ICE MOVEMENT THIS AFTERNOON. AT THIS TIME,
WE KNOW OF A COUPLE OF JAMS ON THE ST JOHN, ONE NEAR GRAND ISLE
AND THE OTHER NEAR ST FRANCIS. THE FIRST OF THESE JAMS WAS NOT
CAUSING ANY FLOODING ISSUES OUTSIDE OF SOME FIELD FLOODING. THE ST
FRANCIS JAM IS SHOWING SIGNS OF MOVMENT PER THE ALLAGASH RIVER
GAGE, SO WE WILL KEEP A CLOSE EYE ON THAT AREA.

ON THE AROOSTOOK, AN ICE JAM REMAINS IN PLACE DOWNSTREAM OF FORT
FAIRFIELD. RIVERSIDE AVENUE IS STILL FLOODED AND IMPASSIBLE AT
THIS TIME. THIS MORNING, THERE HAD ALSO BEEN TWO JAMS UPSTREAM, A
LARGE ONE THAT STRETCHED 3 MILES UPSTREAM FROM THE WASHBURN TRAIN
TRESTLE, AND A SMALLER ONE IN CROUSEVILLE. AN NWS EMPLOYEE
REPORTED A LOT OF ICE MOVING THROUGH PRESQUE ISLE EARLIER THIS
AFTERNOON, SO WE WOULD EXPECT THAT SOME OF THE CROUSEVILLE ICE HAS
RELEASED. HOWEVER, THE WASHBURN RIVER GAGE IS STILL SHOWING A VERY
GRADUAL DECREASE IN FLOW, SO IT APPEARS THAT MUCH OF THE ICE IN
CROUSEVILLE IS STILL THERE, AS IS THE LARGE JAM ABOVE THE GAGE.
PARSONS ROAD IN WASHBURN REMAINS FLOODED AT THIS TIME. THE RIVER
FLOOD WARNING FOR THE WASHBURN GAGE WAS EXTENDED INTO TONIGHT TO
ACCOUNT FOR THE SLOW DOWNWARD TREND IN THE RIVER LEVEL.

ADDITIONAL ICE MOVEMENT WILL BE POSSIBLE THROUGH THE REMAINDER OF
THE WEEKEND. HOWEVER, WITH COOLER OVERNIGHT TEMPERATURES, SLOWLY
DECREASING RIVER FLOWS, AND NO SIGNIFICANT RAINFALL IN THE VERY
NEAR TERM, THE THREAT FOR FLOODING HAS LESSENED SINCE THIS TIME
YESTERDAY. THEREFORE WE ALLOWED THE FLOOD WATCH TO EXPIRE TODAY.
HOWEVER, PERSONS ALONG THE ST JOHN AND AROOSTOOK RIVERS AND THEIR
TRIBUTARIES NEED TO STAY VIGILANT AND WATCH FOR RAPIDLY CHANGING
RIVER CONDITIONS.

&&

.TIDES/COASTAL FLOODING...
WILL NEED TO KEEP AN EYE ON THE
SITUATION FOR THE HIGH TIDE CYCLE LATE MONDAY NIGHT. THE
ASTRONOMICAL TIDES ARE HIGH AND WITH A STORM SURGE OF AROUND 1 FT
AS THE SEAS BUILD THERE WILL BE THE POTENTIAL FOR SOME OVERWASH
AND PERHAPS EVEN MINOR COASTAL FLOODING.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.

&&

$$

NEAR TERM...CB/HEWITT
SHORT TERM...VJN
LONG TERM...VJN
AVIATION...CB/HEWITT/VJN
MARINE...CB/HEWITT/VJN
HYDROLOGY...HASTINGS
TIDES/COASTAL FLOODING...


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