Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 190410 AFDCAR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 1210 AM EDT SUN APR 19 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 TODAY/... 1215 AM UPDATE... DROPPED POPS AS LITTLE PCPN RMNS OVR CWA. ECHOES ON RADAR ARE GNRLY CLDS ACRS NRN ZONES THO STILL MAY SEE A BRIEF SPRINKLE/FLURRY SNEAK DOWN OVER THE NEXT HR OR TWO. EXPECT DRY WX AFT 06Z TONIGHT UNTIL THE BOTTOM FALLS OUT MON AFTN IN WIDESPREAD SOAKING, MAINLY RAIN EVENT, FOR NEW ENGLAND. MASSAGED HRLY T/TD VALUES FOR THE OVRNGT BUT NO OTHER CHGS NEEDED. PREVIOUS DISCUSSION BLO... 930 PM UPDATE...THE HYDROLOGY SECTION HAS BEEN UPDATED WITH THE LATEST FLOOD WARNING THAT WAS RECENTLY ISSUED. SENSIBLE WEATHER HIGHLIGHTS: WEAK LOW PRESSURE MOVING OFF CAPE COD WILL CONTINUE TO PULL AWAY FROM THE SOUTHERN NEW ENGLAND COAST OVERNIGHT. AN INVERTED SFC TROUGH WILL EXTEND FROM THE LOW BACK TO THE DOWNEAST COAST. THE SYSTEM HAS NOT HAD MUCH MOISTURE ASSOCIATED WITH IT...AND HAVE BEEN HARD PRESSED TO FIND MORE THAN A FEW SPOTS WITH MEASURABLE PRECIPITATION THIS EVENING. HAVE MADE SOME ADJUSTMENTS TO LOWER THE POPS/QPF FOR THE REMAINDER OF THE NIGHT. PREVIOUS DISCUSSION... 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 /TONIGHT 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 /04Z 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... 930 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 IS STARTING TO FALL AFTER A BRIEF RISE EARLIER THIS EVENING. GARDNER CREEK ROAD WAS COVERED WITH 1-2 FEET OF WATER...BUT LIKELY IS NOW RECEDING. 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. A JAM REMAINS IN PLACE NEAR THE ST FRANCIS/ALLAGASH LINE THAT HAS FLOODED A PORTION OF ROUTE 161...WHICH IS NOW CLOSED. 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 OVERNIGHT 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 MVMNT 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/FARRAR/HEWITT SHORT TERM...VJN LONG TERM...VJN AVIATION...CB/FARRAR/HEWITT/VJN MARINE...CB/FARRAR/HEWITT/VJN HYDROLOGY...HASTINGS TIDES/COASTAL FLOODING...

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