560  
FXUS61 KCAR 221333  
AFDCAR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CARIBOU ME  
933 AM EDT MON JUL 22 2024  
   
SYNOPSIS
 
 
CANADIAN HIGH PRESSURE WILL BUILD OVER THE AREA TODAY. A WARM  
FRONTAL SYSTEM WILL APPROACH TUESDAY FROM THE SOUTHWEST AND THEN  
BECOME STATIONARY JUST SOUTH OF THE REGION THROUGH THURSDAY AS  
WEAK LOW PRESSURE TRACKS ACROSS THE GULF OF MAINE. A COLD FRONT  
WILL CROSS THE AREA FROM THE WEST BY FRIDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
930 AM UPDATE...  
HIGH PRESSURE OVER SRN NEW ENGLAND WILL SLIDE OFFSHORE TODAY.  
COLD FRONT SITTING OVER SRN QUEBEC WILL CONTINUE TO APPROACH  
THIS AFTERNOON WITH A STRAY SPRINKLE POSSIBLE OVER THE ST. JOHN  
VALLEY. SKIES LOOK TO REMAIN SMOKY FROM WESTERN CANADIAN  
WILDFIRES AND LIKELY GET THICKER THIS AFTERNOON AND EVENING.  
WHILE SMOKE THICKENS UP IN THE UPPER ATMOSPHERE THERE IS VERY  
LITTLE THREAT OF NEAR SURFACE SMOKE. THIS LAYER WILL HAVE LITTLE  
IMPACT ON TEMPS WITH NEAR NORMAL TEMPS EXPECTED THIS AFTERNOON  
 
PREVIOUS DISCUSSION...  
THE COOL CANADIAN HIGH PRESSURE WILL PROVIDE ANOTHER DAY OF  
NEAR SEASONAL TEMPERATURES AND SPRING- LIKE LOW RELATIVE  
HUMIDITY. THE AIR MASS HAS MODIFIED SLIGHTLY SINCE YESTERDAY  
WITH A COMMENSURATE INCREASE IN EXPECTED HIGH TEMPS TODAY. A  
DEEP MIXED LAYER WILL AGAIN DEVELOP, BUT EXPECT LOWER WIND GUSTS  
THAN YESTERDAY WITH THE HIGH CENTERED JUST SOUTH OF THE AREA BY  
AFTERNOON. CLOUDS WILL INCREASE LATER THIS AFTERNOON FROM A  
WEAK COLD FRONT SAGGING SOUTHWARD FROM QUEBEC AND HIGH LEVEL  
MOISTURE ADVANCING NORTHWARD FROM SOUTHERN NEW ENGLAND.  
 
THE COLD FRONT WILL HELP PROVIDE MORE AFTERNOON CLOUD COVER IN  
NORTHERN AROOSTOOK COUNTY DUE TO CUMULUS AND STRATOCU. A STRAY  
SHOWER OR TWO CANNOT BE TOTALLY RULED OUT THIS EVENING. THE  
FRONT WILL STALL THIS EVENING IN NORTHERN AROOSTOOK AND WILL NOT  
BE PROVIDING A REINFORCEMENT TO THE COOL AIR MASS IN PLACE.  
HOWEVER, IT MAY HELP SHUNT RAINFALL SOUTH OF NORTHERN ZONES  
LATER TONIGHT.  
 
THE WARM FRONT TO THE SOUTH WILL BE A MORE SIGNIFICANT WEATHER-  
MAKER LATER TONIGHT. ANOMALOUSLY DEEP MOISTURE CURRENTLY IN THE  
SOUTHEASTERN US WILL ADVECT NORTHEASTWARD TODAY AND TONIGHT.  
STRONG MID-LEVEL MOISTURE TRANSPORT WILL REACH THE SOUTHERN  
PORTION OF THE FORECAST AREA LATER TONIGHT WITH PW VALUES  
RAPIDLY SURGING TOWARDS 1.75 INCHES BY LATE TONIGHT. LOW LEVEL  
MOISTURE PUSHES NORTHWARD FROM THE GULF OF MAINE LATER TONIGHT  
WITH FOG AND LOW CLOUDS LIKELY HITTING THE COAST UNDER AN  
EMERGING FRONTAL INVERSION. 925MB TEMPS ARE EXPECTED TO INCREASE  
TOWARDS 18 TO 20C IN SOUTHERN ZONES BY LATE TONIGHT.  
SIMULTANEOUSLY, A WEAK SHORTWAVE IS EXPECTED TO PROVIDE SOME  
COOLING ALOFT. THE RESULTING ELEVATED INSTABILITY MAY GENERATE  
SOME THUNDERSTORM ACTIVITY LATE TONIGHT IN SOUTHERN ZONES. THE  
DEEP MOISTURE AND WARM CLOUD LAYER...AS WELL AS STORM MOTION  
VECTORS...SUGGEST SOME LOCALLY HEAVY RAINFALL IS POSSIBLE FOR  
SOUTHERN ZONES BY DAYBREAK.  
 

 
   
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
 
 
THE AFOREMENTIONED SHORTWAVE WILL CONTINUE TO AFFECT THE AREA  
DURING THE DAY TUESDAY. THIS WILL MEAN CONTINUED SHOWERS AND  
RUMBLES OF THUNDER TO THE SOUTH OF THE KATAHDIN REGION. WITH  
PWATS CONTINUING TO RUN HIGH, LOCALLY HEAVY RAINFALL WILL STILL  
BE POSSIBLE. NOT TOTALLY OUT OF THE QUESTION THAT A FEW SHOWERS  
MAKE IT INTO NORTHERN AREAS. OTHERWISE, A MAINLY DRY DAY  
EXPECTED THERE. SHOWER CHANCES DECREASE EVERYWHERE TUESDAY NIGHT  
AS THE SHORTWAVE MOVES AWAY. HIGHS ON TUESDAY WILL BE IN THE 70S  
ACROSS THE REGION. TUESDAY NIGHT WILL SEE LOWS IN THE MID TO  
UPPER 50S NORTH OF KATAHDIN, WITH LOWER 60S SOUTH.  
 
A LOW PRESSURE SYSTEM WILL TRACK INTO THE GREAT LAKES DURING THE  
DAY WEDNESDAY, KEEPING A FRONTAL BOUNDARY NEARBY. THIS SETUP WILL  
MEAN MORE SHORTWAVE ENERGY INTO THE AREA BY WEDNESDAY  
AFTERNOON, INCREASING THE SHOWER THREAT ONCE AGAIN. A FEW  
RUMBLES OF THUNDER CANNOT BE RULED OUT, BUT NOT EXPECTING  
ANYTHING STRONG ON WEDNESDAY. HIGHS ON WEDNESDAY WILL ONCE AGAIN  
BE IN THE 70S. HUMIDITY WILL ALSO INCREASE, WITH DEW POINT  
TEMPERATURES RISING INTO THE 60S AREA WIDE. PATCHY FOG WILL BE  
POSSIBLE WEDNESDAY MORNING, WITH AREAS OF FOG POSSIBLE AT THE  
COAST.  
 

 
   
LONG TERM /THURSDAY THROUGH SUNDAY/
 
 
MODEL GUIDANCE CONTINUES TO SHOW A LOW PRESSURE SYSTEM TRACKING  
INTO QUEBEC ON THURSDAY. THIS RESULTS IN A COLD FRONT CROSSING  
THROUGH THE AREA FROM NORTHWEST TO SOUTHEAST LATE THURSDAY OR  
THURSDAY NIGHT. STILL SOME TIMING DIFFERENCES AMONGST THE 00Z  
MODELS, WITH THE ECMWF A FEW HOURS SLOWER THAN THE GFS. THE  
TIMING OF THE FRONT WILL BE IMPORTANT IN DETERMINING THE  
STRENGTH OF ANY THUNDERSTORMS. GUIDANCE SHOWS FAVORABLE SHEAR  
VALUES AND MID-LEVEL LAPSE RATES. THUS, A FRONTAL PASSAGE THAT  
LINES UP WITH DAYTIME HEATING ON THURSDAY WOULD BRING THE  
POTENTIAL FOR STRONG THUNDERSTORMS.  
 
BEHIND THE FRONT, AN UPPER-LEVEL TROUGH COULD BRING A FEW MORE  
SHOWERS AND THUNDERSTORMS FRIDAY AFTERNOON. OTHERWISE, NOT A LOT  
OF COOLER AIR BEHIND THE FRONT, WITH TEMPERATURES AND DEW POINTS  
REMAINING AT OR ABOVE NORMAL. A RIDGE WILL BUILD INTO THE AREA  
OVER THE WEEKEND, LEADING TO INCREASING HEAT AND HUMIDITY  
VALUES. HOWEVER, ASIDE FROM PERHAPS AN ISOLATED SHOWER SATURDAY  
AFTERNOON, THE WEEKEND LOOKS TO BE DRY AT THIS TIME.  
 

 
   
AVIATION /14Z MONDAY THROUGH FRIDAY/
 
 
NEAR TERM: VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD FOR  
AROOSTOOK COUNTY SITES. TERMINALS SUCH AS BGR AND BHB WILL ALSO  
REMAIN VFR UNTIL LATE TONIGHT. BHB STANDS A GOOD CHANCE OF  
BECOMING IFR DUE TO CIGS/VIS AFTER MIDNIGHT WHILE BGR MAY DROP  
TO IFR BY DAYBREAK TUESDAY MORNING. BOTH OF THESE SITES MAY  
EXPERIENCE EMBEDDED THUNDERSTORMS WITH HEAVY RAINFALL LATE  
TONIGHT.  
 
SHORT TERM:  
TUESDAY...MVFR/IFR IN SHOWERS AND EMBEDDED THUNDERSTORMS MAINLY  
SOUTH OF HUL. MAINLY VFR NORTH. SSE WINDS AROUND 5 KTS.  
 
TUESDAY NIGHT-WEDNESDAY...MAINLY VFR THOUGH CANNOT RULE OUT IFR  
AT BGR AND DOWNEAST TERMINALS OVERNIGHT. MAY SEE MVFR MOVE IN  
DURING WEDNESDAY AFTERNOON IN SHOWERS AND EMBEDDED  
THUNDERSTORMS. SSE WINDS AROUND 5 KTS.  
 
WEDNESDAY NIGHT-THURSDAY NIGHT...MAINLY MVFR/IFR IN SHOWERS,  
EMBEDDED THUNDERSTORMS AND FOG. S WINDS 5-10 KTS BECOMING WNW  
5 KTS THURSDAY NIGHT.  
 
FRIDAY...MAINLY VFR. BRIEF MVFR POSSIBLE WITH SCATTERED PM  
SHOWERS AND THUNDERSTORMS. NW WINDS 5-15KTS.  
 

 
   
MARINE
 
 
NEAR TERM: FOG IS EXPECTED TO RETURN LATER TONIGHT AND COULD BE  
LOCALLY DENSE BY TUESDAY MORNING. THERE IS ALSO A RISK OF  
THUNDERSTORMS MOVING ACROSS THE WATERS LATE TONIGHT. SEAS WILL  
REMAIN 2 TO 3 FEET OR LESS. WINDS WILL BECOME SOUTHWEST THIS  
AFTERNOON WITH A FEW GUSTS TO 15 KTS POSSIBLE. A SHIFT TO  
SOUTHERLY WINDS LATER IN THE NIGHT WILL HELP USHER FOG  
NORTHWARD.  
 
SHORT TERM:  
WINDS AND SEAS ARE FORECAST TO REMAIN BELOW SMALL CRAFT ADVISORY  
CRITERIA TUESDAY THROUGH THE END OF THE WEEK. VISIBILITIES WILL  
BE REDUCED AT TIMES IN FOG, ESPECIALLY AT NIGHT, THROUGH FRIDAY  
MORNING BEFORE A FRONT MOVES THROUGH.  
 

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

 
 

 
 
NEAR TERM...BUSTER/MCW  
SHORT TERM...CLARK  
LONG TERM...CLARK  
AVIATION...BUSTER/MCW/CLARK  
MARINE...BUSTER/MCW/CLARK  
 
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