381  
FXUS61 KGYX 250152  
AFDGYX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAY ME  
952 PM EDT FRI SEP 24 2021  
   
SYNOPSIS
 
 
SLOW MOVING COLD FRONT WILL PRODUCE SOME HEAVY RAINFALL AND  
EMBEDDED THUNDERSTORMS TONIGHT INTO SATURDAY MORNING. ANOTHER  
ROUND OF HEAVY SHOWERS SUNDAY AFTERNOON, ESPECIALLY OVER THE  
MID-COAST ANS CENTRAL MAINE. MORE SEASONAL TEMPERATURES AND THE  
THREAT OF SHOWERS IN THE MOUNTAINS ARE EXPECTED FOR MONDAY AND  
TUESDAY,  
 

 
   
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
 
 
UPDATE...  
SHOWERS WILL CONTINUE TO SLOWLY EXIT TO THE EAST LATE THIS  
EVENING IN GOOD AGREEMENT WITH THE LATEST HRRR. RADAR DERIVED  
RAINFALL RATES HAVE COME DOWN SOMEWHAT SINCE EARLIER THIS  
EVENING. WILL CONTINUE TO MONITOR THE MIDCOAST FOR A BAND OF  
POTENTIALLY LOCALLY HEAVY RAIN ENTERING THE REGION FROM CAPE  
COD AND THE GULF OF MAINE AS THIS AREA WILL CONTINUE TO HAVE  
DEEP MOISTURE AND HIGH PRECIPITABLE WATER VALUES.  
 
MADE MINOR ADJUSTMENTS TO TEMPERATURES, DEW POINTS AND WINDS  
THIS HOUR AS DRIER AIR CONTINUES TO POUR IN FROM THE WEST. WILL  
ADD MORE FOG OVER NEW HAMPSHIRE WHERE VISIBILITIES ARE LOWERED.  
 
PREV DISC...  
COLD FRONT IS PROGRESSING THROUGH THE AREA. TO THE WEST, ACROSS  
NH THE CLEARING SKIES ARE APPROACHING. MEANWHILE THROUGH MAINE  
SOUTHERLY FLOW WILL CONTINUE WITH SHOWERS. LOW LEVEL INSTABILITY  
REMAINS, AND SOME WEAK ROTATION HAS BEEN OBSERVED IN THE  
CONVECTIVE LINE. SOME REPORTS OF UP TO 2 INCHES OF RAIN WITHIN  
THE CONVECTIVE LINE.  
 
EXPECT THE FRONT TO CONTINUE TO CROSS THE REGION OVERNIGHT. OVERALL  
THE COVERAGE OF SHOWERS HAS BEEN DECREASING THROUGH THE DAY BUT THE  
HRRR CONTINUES TO SUGGEST THAT SOME RE DEVELOPMENT. THROUGH  
THE MOUNTAINS IS POSSIBLE OVER THE NEXT FEW HOURS. THIS IS  
SUPPORTED BY THE MESOANALYSIS WHICH SHOWS THE HIGHER SHEAR AND  
CAPE HOLDING ON THROUGH THIS AREA, THUS HAVE KEPT THE THUNDER IN  
THE FORECAST THROUGH THE NORTHERN PART OF THE AREA THROUGH  
MIDNIGHT.  
 
TONIGHT THE WESTERN PORTION OF THE CWA SHOULD CLEAR OUT ENOUGH FOR  
VALLEY FOG FORMATION, AND HAVE ADDED THIS TO THE FORECAST. MEANWHILE  
ACROSS THE EASTERN PORTION OF THE AREA, THE FRONT WILL STALL KEEPING  
THE SCATTERED SHOWERS IN PLACE ACROSS THE EASTERN PORTION OF THE  
AREA.  
 

 
   
SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/
 
 
FOR SUNDAY, EXPECT ADDITIONAL RAINFALL, ESPECIALLY OVER THE  
EASTERN PORTION OF THE CWA. THERE ARE TWO SEPARATE FEATURES  
IMPACTING THE AMOUNT OF RAINFALL. FIRST, A WEAK WAVE ROTATING  
AROUND THE MAIN LOW PRESSURE ALOFT WILL PUSH INTO THE REGION.  
THE MORE NEGATIVE TILT THIS CAN ARCHIVE THE GREATER THE  
PRECIPITATION. SECONDLY, LOW PRESSURE ALONG THE EASTERN  
SEABOARD WILL MOVE NORTHWARDS ON SUNDAY, PUSHING ADDITIONAL  
MOISTURE INTO THE STALLED FRONTAL BOUNDARY. THESE TWO FACTORS  
WILL COMBINE TO LEAD TO WIDESPREAD RAINFALL ACROSS ESPECIALLY  
EASTERN MAINE. WITH TWO FEATURE COMPETING THE CONFIDENCE IN THE  
PLACEMENT AND PRECIP MAXIMA STILL REMAINS FAIRLY LOW. HAVE KEPT  
TOTAL QPF FAIRLY CONSERVATIVE, ALTHOUGH CERTAINLY THE UPSLOPE  
FLOW DOES GIVE A POTENTIAL FOR HIGHER TOTALS. THIS TIME THE  
CENTER OF THE RAIN WILL BE ON THE UPPER KENNEBEC BASIN, WHICH  
HAS BEEN PLAGUED BY DROUGHT.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
 
 
WARM RIDGING AT 500 MB WILL BE REPLACE BY COOLER AND MORE SEASONABLE  
TROUGHING OVER THE NE CONUS NEXT WEEK, AS DOUBLE OMEGA BLOCK  
SETTLES ACROSS NOAM AND THE ATLANTIC, WITH CENTRAL TROUGH RIGHT  
OVERHEAD. THIS LOW WILL HOLDS IN PLACE THRU AT LEAST THE MIDDLE OF  
NEXT WEEK, WHEN MODELS DIVERGE ON SOLUTIONS.  
 
STARTING SUNDAY SUN NIGHT SHOULD SEE ANY SHOWERS ASSOCIATED WITH THE  
SLOW MOVING FRONT EXITING TO THE NE IN THE EVENING. THIS WILL BE  
FOLLOWED BY CLEARING IN THE SOUTH, BUT CLOUDS LINGER IN THE N AS THE  
CLOSED UPPER LOW WOBBLES AROUND OVER N QUEBEC. LOWS SUNDAY NIGHT  
WILL BE IN THE LOW-MID 40S IN THE MTNS, TO THE LOW 50S IN THE S.  
 
MON-TUE WILL BE SIMILAR, AS 500 MB CLOSED LOW HANGS OUT TO THE N, A  
AND WAVES OF ENERGY MOVE AROUND THAT LOW. THIS WILL PRODUCE SOME  
ROUNDS OF CLOUDS, AND THE CHANCE OF SHOWERS, MAINLY IN THE MTNS.  
HIGHS WILL BE IN THE LOW-MID 60S IN THE N TO AROUND 70 IN THE S,  
WHICH IS STILL ON THE HIGH SIDE OF NORMAL, AND OVERNIGHT LOWS 40-45  
IN THE MTNS TO THE LOW 50S IN THE S. SKIES WILL VARY FROM PARTLY TO  
MOSTLY CLOUDY THROUGH THE PERIOD WITH MORE CLOUDS IN THE MTNS.  
 
CONFIDENCE DROPS OFF A BIT WED-FRI, WITH MODELS SUGGESTING THAT  
ANOTHER CLOSED LOW BREAKS OFF ON THE ONE TO OUT N AND HEADS  
EQUATORWARD TOWARD THE SE CONUS, WITH SOME RIDGING DEVELOPING  
BETWEEN THE TWO SYSTEMS AS THE PULL AWAY FROM EACH OTHER. CURRENTLY  
THIS WOULD CALL FOR A MAINLY DRY AND SEASONABLE PERIOD, BUT, AGAIN  
CONFIDENCE REMAINS LOW FOR MID-LATE NEXT WEEK.  
 

 
   
AVIATION /02Z SATURDAY THROUGH WEDNESDAY/
 
 
SHORT TERM...COLD FRONT IS MOVING THROUGH THE AREA, WITH MVFR  
CEILINGS CURRENTLY ACROSS NH AND VFR AND CLEARING TO THE WEST.  
THIS CLEARING LINE WILL MOVE EASTWARDS OVERNIGHT. ACROSS MAINE  
POCKETS OF IFR AND WIDESPREAD MVFR WILL CONTINUE UNTIL HE FRONT  
CLEARS THE AREA LATE. VALLEY FOG MAY BRING IFR TO THE WEST IN  
THE MORNING ON SATURDAY BEFORE CONDITIONS IMPROVE TO VFR FOR  
THE DAY.  
 
LONG TERM...ANY FLIGHT RESTRICTIONS EARLY SUNDAY EVENING,  
SHOULD CLEAR OUT OVERNIGHT, EXCEPT FOR LINGERING MVFR CIGS AT  
KHIE. WILL BE MAINLY VFR MONDAY THROUGH WED, BUT AGAIN COULD SEE  
SOME PERIODS OF MVFR CIGS AT KHIE AS FLOW FROM THE NW PERSISTS.  
 

 
   
MARINE
 
 
SHORT TERM...GUSTY SOUTHERLY FLOW AND 5FT SEAS WILL KEEP A SCA  
IN PLACE ACROSS THE REGION THROUGH EVENING. BY TOMORROW MORNING,  
WINDS AND SEAS WILL SUBSIDE AND CONDITIONS WILL REMAIN BELOW SCA  
THROUGH THE WEEKEND.  
 
LONG TERM...WINDS/SEAS EXPECTED TO STAY BELOW SCA CRITERIA MON-  
WED.  
 

 
   
HYDROLOGY
 
 
HEAVY RAIN SHOWERS WILL CONTINUE THROUGH THIS EVENING WITH THE  
POTENTIAL THREAT FOR FLOODING ALONG THE MIDCOAST REGION OF MAINE.  
 
THE THREAT FOR FLOODING DOES INCREASE ON SUNDAY THROUGH THE  
UPPER ANDRO AND UPPER KENNEBEC BASINS WHERE THE FOCUS OF THE  
HEAVIEST RAINFALL EXISTS. 6HR RFC GUIDANCE SUGGESTS THAT 2-3  
INCHES IN 6 HRS WOULD BE ENOUGH TO PUSH THE RIVERS TO FLOOD  
STAGE BUT SUSPECT THE SUNDAY RAINFALL WILL BE OVER A LONGER  
PERIOD THAN THAT. THUS WHILE FLOODING CANNOT BE RULED OUT FEEL  
THE MOST LIKELY SCENARIO IS A BENEFICIAL RAIN TO THE NORTHERN  
PORTION OF THE AREA.  
 

 
   
GYX WATCHES/WARNINGS/ADVISORIES
 
 
ME...NONE.  
NH...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT SATURDAY FOR ANZ150>154.  
 

 
 

 
CANNON  
 
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