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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